DE102019006118B4 - OIL GROOVE FOR GEARBOX - Google Patents

Abstract

An oil groove (9) for a transmission (2) in which an oil passage (92, 93) surrounded by a bottom wall (92c, 93c, 93d, 93e, 93f) and side walls (92d, 92e, 93g, 93h) projecting upward from the bottom wall (92c, 93c, 93d, 93e, 93f) is formed, the oil groove (9) for the transmission (2) comprising:
a collecting section (90) into which lubricating oil conveyed from a lower section of the transmission (2) is to flow, and
a supply end portion (95) designed to supply lubricating oil to a shaft end of a transmission shaft (3) carrying a transmission gear (30-35),
wherein an intermediate storage portion (93a) configured to store the lubricating oil and at which the bottom wall (93c) is located lower than a first bottom wall portion (90a) which is the bottom wall at the collecting portion (90) and a second bottom wall portion (95a) which is the bottom wall at the supply end portion (95) is provided between the collecting portion (90) and the supply end portion (95);
wherein at least a portion (93) of the oil passage (92, 93) is located above a transmission gear (41), and
wherein a part of the bottom wall (93c, 93d) located above the transmission gear (41) is provided with a drip hole (101) designed to allow lubricating oil to drip from the oil passage (93) to the transmission gear (41),
characterized in that
the part of the bottom wall (93c, 93d) located above the transmission gear (41) has an arc portion (93d) having an arc shape along an outer periphery of the transmission gear (41), and the drip hole (101) is formed on the arc portion (93d).

Description

Technical area

The present invention relates to an oil groove that forms a lubricating structure of a transmission.

background

In a transmission provided in a vehicle or the like, a lubricating structure is known in which lubricating oil in a lower portion of a transmission case is raised by operation of a gear or the like, and in which lubricating oil dispersed and flowing in the transmission case is collected and supplied to a lubrication target portion through an oil groove. The oil groove has a groove-like oil passage which is provided at an upper side inside the transmission and which guides the lubricating oil to the lubrication target portion.

Citation list

Patent specification

Patent document 1: JP-A-2011-137493

Summary of the invention

Technical problem

In a transmission, a gear immersed in lubricating oil stored on a lower side (an oil reservoir) is rotated, thereby bringing up the lubricating oil. In a stopped state or a halted state of a prime mover, the lubricating oil accumulates on the lower side, and an amount of the lubricating oil in the oil reservoir increases because the gear does not rotate. When traveling or when the prime mover is rotationally driven so that the gear rotates, the lubricating oil circulates in the transmission, the amount of lubricating oil in the reservoir decreases, and a liquid level of the lubricating oil lowers. The amount of lubricating oil in the transmission is set relatively large in consideration of initial lubrication immediately after a start of the prime mover, that is, when starting traveling from the halted state, so that at least a portion requiring lubrication is below the liquid level of the lubricating oil. However, with this amount of lubricating oil, the lubricating oil may be scattered and overflowed in the transmission during driving, in which case a stirring resistance when rotating the gear becomes unnecessarily large due to the viscosity of the lubricating oil or the like. As a result, a driving efficiency may decrease and a fuel efficiency may deteriorate.

Then, a technique is known in which a catch tank capable of storing lubricating oil is provided separately from a lower oil reservoir in a transmission to obtain an appropriate amount of lubricating oil while reducing oil resistance. The catch tank receives and temporarily stores excess lubricating oil dispersed or flowing in a transmission case while the prime mover is driven or during traveling, and adjusts an amount of the lubricating oil in contact with a gear (which is stirred thereby) or the like to an appropriate amount.

In a current transmission lubrication structure, the above-described catch tank is provided independently. However, the provision of the independent catch tank is limited in terms of installation space and cost. Similar to the oil groove, the catch tank stores lubricating oil above the lower layer portion of the transmission, but it may be difficult to add a catch tank for ensuring a capacity for temporarily storing the lubricating oil in a lubrication structure having an oil groove depending on a configuration within the transmission.

In addition, the structure of the transmission is complicated, and with a current oil groove, it may be difficult to supply lubricating oil to a specific lubrication target portion. In particular, in a manual type transmission, a switching device that transmits a switching operation of a passenger or a driver to a transmission gear mechanism is provided at an upper portion of the transmission. Since the switching device partially occupies an upper space within the transmission, a degree of freedom in arranging and a shape of the oil groove may be limited.

JP 2002-054729 A , which shows an oil groove according to the preamble of the claim, addresses the problem of how to provide an oil groove plate of a transmission which is capable of effectively removing foreign matter in the oil. As a solution, a foreign matter collecting container is proposed with a base which is lower than the bottom walls of the oil groove plate, the foreign matter collecting container being part of an oil passage which is groove-shaped in cross section and has the bottom walls and a pair of side walls.

JP 2011-185332 A deals with the problem of how to provide an oil supply device for a gearbox that reduces the resistance to movement caused by oil and also reliably lubricates a rotating element without increasing the assembly effort and the number of components. As a solution, it is proposed to arrange an oil collecting container (storage element) with a storage section and an opening that directs the oil scraped upwards into the storage section above an input shaft and an output shaft.

JP 2013-092230 A addresses the problem of how to provide an oil supply device of a transmission capable of improving fuel consumption in wide power ranges from low-speed driving mode to high-speed driving mode. As a solution, it is proposed that a storage element is arranged on an upper surface of an output shaft of a transmission mechanism. The storage element has openings for supplying scraped oil to a storage part.

Solution to the problem

The present invention has been made in view of the above problems, and provides an oil groove for a transmission which can optimize a flow state of lubricating oil and improve a lubricating performance with a simple and space-saving configuration.

The above object is achieved by an oil trough according to claim 1 or 7. The dependent claims relate to further distributable aspects of the invention.

Effects of the invention

According to the present invention, an oil groove for a transmission can be obtained which can optimize a cycle state of the lubricating oil and improve a lubricating performance with a simple and space-saving configuration.

Short description of the drawings

• 1 is a plan view of a transmission according to a present embodiment.
• 2 is a side view of a transmission viewed from the left with a left housing removed.
• 3 is a side view of a transmission viewed from the right with a right housing removed.
• 4 is a side view of the right housing and an oil groove viewed from the left.
• 5 is a side view of the left housing and an oil groove viewed from the right.
• 6 is a side view of the left case viewed from the right.
• 7 is a cross-sectional view along a line AA of 1 .
• 8th is a cross-sectional view taken along a line BB from 1 .
• 9 is a cross-sectional view along a line CC of 1 .
• 10 is a cross-sectional view along a line DD of 2 .
• 11 is a view of an internal switching mechanism, a transmission gear mechanism, and the oil groove viewed from above.
• 12 is a view of the transmission gear mechanism and oil groove viewed from above.
• 13 is a view of the transmission gear mechanism and oil groove viewed from below.
• 14 is a front perspective view of the oil trough.
• 15 is a rear perspective view of the oil trough.
• 16 is a front view of the oil trough.

Description of the embodiments

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the accompanying drawings and description, up, down, front, back, left, right, up and down directions are in a state in which a transmission is mounted on a vehicle (not shown). The left-right direction of the vehicle is also referred to as a vehicle transverse direction. In the following drawings, some configurations are omitted for the convenience of explanation.

A schematic configuration of a manual transmission for a vehicle according to the present embodiment will be described with reference to the drawings. The vehicle according to the present embodiment is a so-called FF type four-wheeled vehicle whose front wheels are driven by a prime mover mounted on a front portion of a vehicle body. As shown in 1 As shown, a drive machine 1 and a transmission 2 are mounted in the left-right direction on the mounted on the portion of the vehicle body where the prime mover 1 is located on a right side and the transmission 2 is located on a left side of the prime mover 1.

The engine 1 is, for example, an internal combustion engine such as a gasoline engine, and various components such as a crankshaft (not shown) are housed in an engine case (not shown). An axial direction of the crankshaft is aligned in the vehicle transverse direction (the left-right direction). The engine 1 is not limited to a gasoline engine, and may be another type of engine such as a diesel engine.

The transmission 2 is a so-called stepped manual transmission that shifts by manual operation of a passenger. The stepped manual transmission may also be a stepped transmission in which a shift operation is performed using an actuator instead of manual operation of the passenger. The transmission 2 shifts (retards) rotation of the crankshaft step by step and transmits it to a drive wheel (not shown) with the transmission gear mechanism 10. The transmission 2 is configured by assembling various components in a transmission case 20. Examples of the various components include a clutch (not shown), various shafts and a plurality of transmission gears that constitute a transmission gear mechanism 10, a switching device 7, an internal switching mechanism 8, and the like.

As in 1 As shown, the transmission case 20 is divided into left and right in the left-right direction and includes a right case 21 and a left case 22. The right case 21 forms a right space (an arrangement space for a clutch) of the transmission case 20, the left case 22 forms a left space (an arrangement space for the transmission gear mechanism 10) of the transmission case 20 together with the right case 21. The right case 21 has a partition wall 23 which divides a space in the transmission case 20 into left and right (the left space and the right space) (see 4 , 8th and 10 ). The left housing 22 has a left end wall 25 closing a left end side and a peripheral wall 24 extending from a peripheral edge of the left end wall 25 rightward to the partition wall 23 (see 10 ). The left space is surrounded by and defined by the peripheral wall 24 and the left end wall 25 of the left housing 22 and the partition wall 23 of the right housing 21.

As in 3 As shown, the peripheral wall 24 of the left housing 22 includes an upper wall portion 24a located at an upper front portion, a front wall portion 24b extending downward from a front end portion of the upper wall portion 24a, a rear wall portion 24c extending downward from a rear end portion of the upper wall portion 24a, and a bottom wall portion 24d connecting the lower portions of the front wall portion 24b and the rear wall portion 24c.

The right case 21 and the left case 22 constitute the transmission case 20 by fixing a mating surface 21a and a mating surface 22a thereof with a plurality of bolts (not shown). In the left case 22, an end surface of the peripheral wall 24 constitutes the mating surface 22a. An engine case (crank case) is fixed to a right side of the right case 21.

As in 10 , the right housing 21 has a peripheral wall protruding leftward from a peripheral edge of the partition wall 23, and an end surface of the peripheral wall forms the fitting surface 21a. In a state where the right housing 21 and the left housing 22 are combined with each other, the peripheral wall of the right housing 21 and the peripheral wall 24 of the left housing 22 are continuous to form a peripheral wall of the arrangement space for the transmission gear mechanism 10. For convenience of description, the following peripheral wall 24 includes, unless limited to the case, the peripheral wall 24 of the right housing 21 and the peripheral wall 24 of the left housing 22. Therefore, in 2 , 4 and 8th the peripheral wall (a peripheral wall, an upper wall portion, a front wall portion, a rear wall portion, and a bottom wall portion) of the right housing 21 is designated by the same reference numerals (24, 24a, 24b, 24c, 24d) as the peripheral wall 24 of the left housing 22.

A clutch (not shown) arranged coaxially with the crankshaft is provided in the right case 21 (the right space) to the right of the partition wall 23. In the left case 22 (the left space) to the left of the partition wall 23, an input shaft 3, a countershaft 4 and a reverse shaft 5 as transmission shafts constituting the transmission gear mechanism 10 are arranged (see 2, 3, 11 to 13 ). These transmission shafts are arranged so that the axial directions thereof are arranged in the vehicle transverse direction similar to the crankshaft.

The input shaft 3 is a shaft through which power is input from the engine 1 via a clutch. The input shaft 3 is arranged coaxially with the crankshaft. As shown in 2 and 3 , the input shaft 3 is arranged in a side view at a position slightly in front of and above a center of the transmission case 20. As shown in 12 and 13 As shown, a bearing 3a and a bearing 3b are attached to the input shaft 3. The input shaft 3 is supported via the bearing 3a and the bearing 3b so as to be rotatable about an axis with respect to the partition wall 23 of the right housing 21 and the left end wall 25 of the left housing 22. A support recess 110 which holds the bearing 3a is formed on the partition wall 23 of the right housing 21 (see 4 ) and a support recess 111, which holds the bearing 3b, is formed on the left end wall 25 of the left housing 22 (see 5 and 6 ). A through hole 110a penetrating the partition wall 23 is formed at a center of the support recess 110. The input shaft 3 is inserted into the through hole 110a, and an end portion on the right side of the input shaft 3 passes through the through hole 110a and projects into the right housing 21 (the right space) (see 10 ). The clutch (not shown) is attached to the right end of the input shaft 3.

On the input shaft 3, a first input gear 30, a second input gear 31, a third input gear 32, a fourth input gear 33 and a fifth input gear 34 are carried sequentially from the right side (see 11 to 13 ). Among these input gears, a diameter of the first input gear 30 is the smallest, and the second input gear 31, the third input gear 32, the fourth input gear 33, and the fifth input gear 34 have a diameter that gradually increases. Note that the input gears may also be referred to as drive gears. A reverse input gear 35 is further supported on the input shaft 3 between the first input gear 30 and the second input gear 31.

The first input gear 30, the second input gear 31, and the reverse input gear 35 are gears that rotate integrally with the input shaft 3. The third input gear 32, the fourth input gear 33, and the fifth input gear 34 are idle gears that are supported so as to be rotatable relative to the input shaft 3 and rotate together with the input shaft 3 when shift sleeves described later (a second shift sleeve 36 and a third shift sleeve 37) are engaged.

As in 2 and 3 shown, the countershaft 4 is arranged behind and slightly below the input shaft 3. As in 12 and 13 As shown, a bearing 4a and a bearing 4b are mounted on the countershaft 4. The countershaft 4 is supported via the bearing 4a and the bearing 4b so as to be rotatable about an axis with respect to the partition wall 23 of the right housing 21 and the left end wall 25 of the left housing 22. A support recess 112 which holds the bearing 4a is formed on the partition wall 23 of the right housing 21 (see 4 ) and a support recess 113, which holds the bearing 4b, is formed on the left end wall 25 of the left housing 22 (see 5 and 6 ).

On the countershaft 4, a first countershaft gear 40, a second countershaft gear 41, a third countershaft gear 42, a fourth countershaft gear 43 and a fifth countershaft gear 44 are carried sequentially from the right side (see 11 to 13 ). Among these counter gears, a diameter of the first counter gear 40 is the largest, and the second counter gear 41, the third counter gear 42, the fourth counter gear 43, and the fifth counter gear 44 have a diameter that gradually decreases. The counter gears may be referred to as driven gears. The first counter gear 40 and the first input gear 30, the second counter gear 41 and the second input gear 31, the third counter gear 42 and the third input gear 32, the fourth counter gear 43 and the fourth input gear 33, the fifth counter gear 44 and the fifth input gear 34 are respectively meshed with each other and respectively form shift stages including a first gear, a second gear, a third gear, a fourth gear, and a fifth gear. A final drive gear 45, which is in engagement with a final driven gear 60 on the right side of the first countershaft 40, is carried by the countershaft 4.

The third counter gear 42, the fourth counter gear 43, the fifth counter gear 44 and the final drive gear 45 are gears that rotate integrally with the counter shaft 4. The first counter gear 40 and the second counter gear 41 are idle gears that are supported so as to be rotatable relative to the counter shaft 4 and rotate together with the counter shaft 4 when a shift sleeve described later (a first shift sleeve 46) is engaged.

As in 2 and 3 As shown, a reverse shaft 5 is arranged slightly in front of and below the input shaft 3. A right end portion of the reverse shaft 5 is inserted into a support recess 114. which is formed on the partition wall 23 of the right housing 21 (see 4 ). A screw hole 5a (see 13 ) oriented in a radial direction is formed at a left end portion of the reverse shaft 5 and a bolt 115 (see 5 and 6 ) to be fixed from an outside of the left housing 22 is fixed with respect to the screw hole 5a. By screwing the screw hole 5a and the bolt 115, the reverse shaft 5 is fixed to the left housing 22 and is restricted in its movement in an axial direction and rotation about an axis. A reverse idle gear 50 is carried on the reverse shaft 5 (see 13 ). The reverse idle gear 50 is an idle gear supported so as to be rotatable relative to the reverse shaft 5 and capable of moving in the axial direction of the reverse shaft 5.

A reverse drive lever 51 which moves the reverse idle gear 50 along the reverse shaft 5 is provided (see 11 to 13 ). The reverse drive lever 51 is pivotally supported by a bracket 52 fixed in the gear case 20 and has two arms branching from this pivotally supported portion. An outer end of one arm of the reverse drive lever 51 is engaged with a recess formed on the reverse idle gear 50, and a connecting hole 51a is formed on the other arm of the reverse drive lever 51. The reverse idle gear 50 moves in the axial direction of the reverse shaft 5 in accordance with rotation (swing) of the reverse drive lever 51. When the reverse idle gear 50 moves in the axial direction of the reverse shaft 5, the reverse idle gear 50 meshes with the reverse input gear 35 of the input shaft 3 and with a reverse counter gear 47 formed on the first shift sleeve 46 which will be described later, and the reverse idle gear 50 reverses the rotation of the input shaft 3 and transmits the rotation to the counter shaft 4. An outer end of a reverse operating arm 83d which will be described later is inserted into the connecting hole 51a of the other arm of the reverse drive lever 51.

As in 11 to 13 , synchronizers (comprising the shift sleeves) are arranged at predetermined positions on the input shaft 3 and the countershaft 4, respectively. The first shift sleeve 46 is arranged on the countershaft 4 between the first counter gear 40 and the second counter gear 41. The reverse counter gear 47 integrated with the first shift sleeve 46 is provided on a side portion of the first shift sleeve 46. On the input shaft 3, the second shift sleeve 36 is arranged between the third input gear 32 and the fourth input gear 33, and the third shift sleeve 37 is arranged on the left side of the fifth input gear 34.

The first shift sleeve 46 is attached to the countershaft 4 via a hub (not shown), rotates integrally with the countershaft 4, and is supported so as to be slidable in the axial direction of the countershaft 4. Each of the second shift sleeve 36 and the third shift sleeve 37 is attached to the input shaft 3 via a hub (not shown), rotates integrally with the input shaft 3, and is supported so as to be slidable in the axial direction of the input shaft 3.

When a shift sleeve 36, 37, 46 or the reverse idle gear 50 is displaced in the axial direction in accordance with a shifting operation of the passenger, gear pairs of the input gear and the counter gear which transmit rotation between the input shaft 3 and the counter shaft 4 are switched to perform shifting, the details of which will be described later.

A differential device 6, which is a differential gear device that transmits a driving force from the countershaft 4 to both wheels (drive wheels), is provided under the countershaft 4 (see 2, 3, 11 to 13 ). The differential device 6 includes a differential case 61 in which a differential gear is incorporated, and the final driven gear 60 is fixed in the differential case 61. A rotation axis of the final driven gear 60 is arranged along the vehicle transverse direction. The final driven gear 60 has a diameter larger than that of the gears carried by the input shaft 3, the counter shaft 4 and the reverse shaft 5, and is arranged at the rear of a lower portion in the transmission case 20 in a side view. In the vehicle transverse direction, the final driven gear 60 is arranged at a position near a left surface of the partition wall 23 (see 10 ) .

As in 1 , the gear housing 20 is smaller toward the left side. Therefore, a cross-sectional shape of the peripheral wall 24 in the gear housing 20 varies depending on a position in the left-right direction. For example, as shown in 3 to 6 shown in a section near the partition wall 23, the rear wall section 24c and the bottom wall section 24d bulge rearward and downward to provide a space for Receiving the final drive gear 60. On the other hand, the peripheral wall 24 is in a position spaced to the left from the partition wall 23 ( 7 ) does not have a bulged portion on a rear underside receiving the final drive gear 60.

The internal switching mechanism 8 is arranged above the gear mechanism 10 on the left side of the partition wall 23 (see 2 and 3 ). The switching device 7 is arranged behind the internal switching mechanism 8. That is, the switching device 7 is arranged behind the input shaft 3 and the countershaft 4 in the front-rear direction. A switching operation of the passenger is transmitted to the switching device 7, and the internal switching mechanism 8 is operated via the switching device 7 to switch the gear pair of the transmission gear mechanism 10 which transmits the driving force between the input shaft 3 and the countershaft 4.

The switching device 7 includes a switching and selecting shaft 70 inserted into the left housing 22 with an axial direction thereof oriented in the up-down direction, and a switching case 71 supporting the switching and selecting shaft 70. An opening 26 ( 7 ) penetrating the upper wall portion 24a of the peripheral wall 24 in the up-down direction is formed on the left housing 22. The switch housing 71 includes a lid portion 71a located on an upper surface side of the left housing 22 to cover the opening 26, an upper projection portion 71b projecting upward from the lid portion 71a, and a hanging portion 71c projecting downward from the lid portion 71a to be fitted into the left housing 22.

As in 7 , the switching and selecting shaft 70 is inserted into a shaft hole formed in the switching case 71 with an axis thereof oriented in the up-down direction, and is supported by the switching case 71 so as to be movable in the axial direction (a selecting direction) and rotatable about the axis (a switching direction). An upper end portion of the switching and selecting shaft 70 projects upward from the upper projection portion 71b, and a base end portion 72a of an outer switching lever 72 is fixed to the projection portion. As shown in 7 As shown, the base end portion 72a includes a tubular portion into which the upper end portion of the shift and select shaft 70 is inserted and fixed, and a pair of plate-shaped portions supported by the tubular portion at an interval in the up-down direction. The outer shift lever 72 pivots together with the shift and select shaft 70 about the axis of the shift and select shaft 70. An engaging portion 73a of the outer shift lever 73 is engaged with the base end portion 72a of the outer shift lever 72. The outer shift lever 73 is pivotally supported by the shift housing 71 so as to pivot about a shaft 73b perpendicular to the up-down direction. The engaging portion 73a is provided eccentrically to the shaft 73b, and the engaging portion 73a is inserted between the pair of plate-shaped portions of the base end portion 72a. When the outer select lever 73 pivots about the shaft 73b, the engaging portion 73a moves in the up-down direction, movement of the engaging portion 73a is transmitted to the base end portion 72a, and the outer shift lever 72 and the shift and select shaft 70 move in the up-down direction. A lower portion of the shift and select shaft 70 is inserted into the left case 22 through the opening 26.

In the left housing 22, a shaft support section 29 is provided in front of the rear wall section 24c (see 6 and 7 ). The shaft support portion 29 has a hole extending in the up-down direction into which a lower end portion of the switching and selecting shaft 70 is inserted and supports the lower end portion of the switching and selecting shaft 70. The shaft support portion 29 allows movement in the axial direction (the selecting direction) and rotation about the axis (the switching direction) of the switching and selecting shaft 70.

One end of a shift cable (not shown) is connected to an outer end side of the outer shift lever 72 spaced from the base end portion 72a. The other end of the shift cable is connected to a shift lever (not shown) operated by a passenger. One end of a select cable (not shown) is connected to an outer end side of the outer select lever 73 spaced from the engaging portion 73a and the shaft 73b. The other end of the select cable is connected to the shift lever.

When the shift lever is operated by the passenger or driver in the select direction, the outer select lever 73 moves the shift and select shaft 70 in the axial direction (the select direction) via the outer shift lever 72. On the other hand, when the shift lever is operated in the shift direction by the passenger, the outer shift lever 72 pivots around the shift and select shaft 70 around the axis (in the shift direction). An operation of the shift lever in the select direction by the passenger is also called a select operation, and an operation in the shift direction is called a shift operation.

As described above, the switching device 7 according to the present embodiment includes, for example, a so-called remote-controlled switching device that transmits an operating force to the outer shift lever 72 and the outer select lever 73 via a cable, but is not limited to this and can be appropriately changed. For example, the switching device 7 may be a so-called direct-controlled switching device in which the shift lever is directly attached to the shift and select shaft 70.

A control cam element 74 is attached to a part of the switching and selection shaft 70, which is inserted into the left housing 22 (see 7 ) is provided. The cam member 74 is fixed to the shift and select shaft 70, and the cam member 74 moves in the axial direction or rotates together with the shift and select shaft 70 in accordance with a shift operation or select operation of the passenger. A finger portion 74a is provided at an outer peripheral portion of the cam member 74.

Furthermore, as in 7 , a detent plate 77 is provided on the shift and select shaft 70 so as to cover upper, lower and front sides of the cam member 74. The detent plate 77 includes an upper plate 77a located above the cam member 74 and having a front end bent downward, and a lower plate 77b located below the cam member 74 and having a front end bent upward. Outer ends of the bent portions of the upper plate 77a and the lower plate 77b are spaced from each other in the up-down direction to form a slot 77c. The finger portion 74a of the cam member 74 projects forward of the detent plate 77 through the slot 77c.

The locking plate 77 is restricted in its movement in the axial direction relative to the switching and selecting shaft 70 by a snap ring (not shown) and moves in the up-down direction together with the switching and selecting shaft 70. Furthermore, the locking plate 77 is fitted in a recess formed on the hanging portion 71c of the switching housing 71 and is restricted in its rotation about the axis of the switching and selecting shaft 70 (see 10 ). The locking plate 77 is formed with a through hole through which the switching and selecting shaft 70 is inserted so as to be relatively rotatable. Thus, the locking plate 77 moves together with the switching and selecting shaft 70 in the axial direction (selecting direction) without following rotation of the switching and selecting shaft 70 in the axial direction (switching direction).

A switching guide 78 is provided above the locking plate 77 (see 2 and 7 ). The shift guide 78 is fixed to the shift and select shaft 70 and moves in the up-down direction (the select direction) and around the axis (the shift direction) together with the shift and select shaft 70.

A guide groove (not shown) having a shape along a shift operation pattern is formed on an outer peripheral surface of the shift guide 78. The guide groove includes three horizontal grooves arranged one above or one below the other and a vertical groove extending vertically through centers of the horizontal grooves. An outer end of a guide pin (not shown) provided on the hanging portion of the shift housing 71 is inserted into the guide groove. When the shift and select shaft 70 moves in the up-down direction (the select direction) and rotates in the shift direction, the guide pin moves along the guide groove. The horizontal grooves of the guide groove correspond to the shift direction, and the vertical groove corresponds to the select direction. Since the guide pin is in contact with wall surfaces of the guide groove, a range of movement and an amount of movement of the shift and select shaft 70 are limited, and rattling of the shift and select shaft 70 is prevented.

A cam surface (not shown) is formed at a position other than the finger portion 74a on the outer peripheral portion of the cam member 74. A piston 75 (see 10 ) is provided at a position facing the cam surface of the cam member 74. The piston 75 includes a fitting portion which is movable in the tube portion supported by the detent plate 77 in a direction orthogonal to the axial direction of the switching and selecting shaft 70, and the fitting portion is biased in a direction in contact with the cam surface. Since the fitting portion of the piston 75 is fitted to the cam surface of the cam member 74, when the switching and selecting shaft 70 is operated, a predetermined resistance can be applied and a position of the cam member 74 in the switching direction can be maintained.

The internal switching mechanism 8 moves a predetermined shift sleeve in the axial direction in accordance with an operation (rotation) of the switching and selection shaft 70 in the switching direction. The internal switching mechanism 8 comprises a first switching unit 81, a second switching unit 82 and a third switching unit 83 (see 10 and 11 ).

The first switching unit 81 moves the first shift sleeve 46 in the axial direction of the countershaft 4. The first switching unit 81 includes a first shift shaft 81a extending in the left-right direction above the countershaft 4, a first shift yoke 81b engageable with the finger portion 74a of the cam member 74, and a first shift fork 81c engaged with the first shift sleeve 46.

An axial direction of the first shift shaft 81a is parallel to the axial directions of the input shaft 3, the countershaft 4 and the reverse shaft 5. Both ends of the first shift shaft 81a are guided through a shaft guide hole 120 (see 4 ) formed on the partition wall 23 of the right housing 21, and a shaft guide hole 121 (see 5 and 6 ) formed on the left end wall 25 of the left housing 22 so as to be slidable in the axial direction (the left-right direction).

The first switching yoke 81b is a plate-shaped body extending in a horizontal direction and having a front end portion connected to the first switching shaft 81a (see 2 , 3 and 7 ). A rear end portion of the first switching yoke 81b is formed with a recess that is opened rearward. The finger portion 74a of the cam member 74 or the outer end of the bent portion of the upper plate 77a is disposed in the recess. When the position of the finger portion 74a in the up-down direction coincides with a height position of the first switching yoke 81b, the finger portion 74a is located in the recess of the first switching yoke 81b and can be engaged therewith.

The first shift fork 81c is a plate-like body having a C-shape in a side view, whose outer end portion branches into two. A base end portion of the first shift fork 81c is connected to the first shift shaft 81a, and an outer end portion of the first shift fork 81c is engaged with a groove formed on the first shift sleeve 46.

The first shift unit 81 is an integrated structure in which the first shift shaft 81a, the first shift yoke 81b, and the first shift fork 81c are coupled to each other, and when movement of the finger portion 74a in the shift direction is transmitted to the first shift yoke 81b, the first shift shaft 81a shifts in the axial direction. Due to the displacement of the first shift shaft 81a, the first shift fork 81c moves the first shift sleeve 46 in the axial direction of the countershaft 4, and the engagement relationship between the first counter gear 40 and the second counter gear 41 adjacent to the first shift sleeve 46 is switched. Specifically, the first shift unit 81 has a neutral position in which neither the first counter gear 40 nor the second counter gear 41 is engaged with the first shift sleeve 46. When the first shift unit 81 moves to the right from the neutral position, the first shift sleeve 46 is engaged with the first counter gear 40, and when the first shift unit 81 moves to the left from the neutral position, the first shift sleeve 46 is engaged with the second counter gear 41.

When the first shift sleeve 46 is engaged with the first counter gear 40, the counter gear 40 rotates integrally with the counter shaft 4. Then, rotation of the input shaft 3 is transmitted from the first input gear 30 to the counter shaft 4 via the first counter gear 40. This state is a gear ratio of the first speed in the transmission gear mechanism 10.

When the first shift sleeve 46 is engaged with the second counter gear 41, the second counter gear 41 rotates integrally with the counter shaft 4, then rotation of the input shaft 3 is transmitted from the second input gear 31 to the counter shaft 4 via the second counter gear 41. This state is a gear ratio of the second speed in the transmission gear mechanism 10.

The second switching unit 82 moves the second shift sleeve 36 in the axial direction of the input shaft 3. The second switching unit 82 includes a second shift shaft 82a extending in the left-right direction ahead of the first shift shaft 81a, a second shift yoke 82b engageable with the finger portion 74a of the cam member 74, and a second shift fork 82c engaged with the second shift sleeve 36.

An axial direction of the second shift shaft 82a is parallel to the axial directions of the input shaft 3, the counter shaft 4 and the reverse shaft 5. Both ends of the second shift shaft 82a are passed through a shift guide hole 122 (see 4 ) formed on the partition wall 23 of the right housing 21, and a shaft guide hole 123 (see 5 and 6 ) formed on the left end wall 25 of the left housing 22 so as to be slidable in the axial direction (the left-right direction).

The second switching yoke 82b is a plate-shaped body extending in a horizontal direction and having a front end portion connected to the second switching shaft 82a (please refer 2 , 3 and 7 ). A rear end portion of the second switching yoke 82b is formed with a recess that is opened rearward, and the finger portion 74a of the cam member 74, the outer end of the bent portion of the upper plate 77a, or the outer end of the bent portion of the lower plate 77b is disposed in the recess. When the position of the finger portion 74a in the up-down direction coincides with a height position of the second switching yoke 82b, the finger portion 74a is located in the recess of the second switching yoke 82b and can be engaged therewith.

The second shift fork 82c is a plate-like body having a C-shape in a side view, whose outer end portion is branched into two. A base end portion of the second shift fork 82c is connected to the second shift shaft 82a, and an outer end portion of the second shift fork 82c is engaged with a groove formed on the second shift sleeve 36.

The second shift unit 82 is an integral structure in which the second shift shaft 82a, the second shift yoke 82b, and the second shift fork 82c are coupled to each other, and when movement of the finger portion 74a in the shift direction is transmitted to the second shift yoke 82b, the second shift shaft 82a shifts in the axial direction. Due to the displacement of the second shift shaft 82a, the second shift fork 82c moves the second shift sleeve 36 in the axial direction of the input shaft 3, and the engagement relationship between the third input gear 32 and the fourth input gear 33 adjacent to the second shift sleeve 36 is switched. Specifically, the second shift unit 82 has a neutral position at which neither the third input gear 32 nor the fourth input gear 33 is engaged with the second shift sleeve 36. When the second shift unit 82 shifts to the right from the neutral position, the second shift sleeve 36 is engaged with the third input gear 32, and when the second shift unit 82 shifts to the left from the neutral position, the second shift sleeve 36 is engaged with the fourth input gear 33.

When the second shift sleeve 36 is engaged with the third input gear 32, the third input gear 32 rotates integrally with the input shaft 3. Then, rotation of the input shaft 3 is transmitted from the third input gear 32 to the countershaft 4 via the third counter gear 42. This state is a gear ratio of the third speed in the transmission gear mechanism 10.

When the second shift sleeve 36 is engaged with the fourth input gear 33, the fourth input gear 33 rotates integrally with the input shaft 3. Then, rotation of the input shaft 3 is transmitted from the fourth input gear 33 to the counter shaft 4 via the fourth counter gear 43. This state is a gear ratio of the fourth speed in the transmission gear mechanism 10.

The third switching unit 83 moves the third shift sleeve 37 in the axial direction of the input shaft 3 and moves the reverse idle gear 50 in the axial direction of the reverse shaft 5 via the reverse drive lever 51. The third switching unit 83 includes a third shift shaft 83a extending in the left-right direction above and in front of the second shift shaft 82a, a third shift yoke 83b engageable with the finger portion 74a of the cam member 74, a third shift fork 83d engaged with the third shift sleeve 37, and the reverse operating arm 83d connected to the reverse drive lever 81.

An axial direction of the third shift shaft 83a is parallel to the axial directions of the input shaft 3, the countershaft 4 and the reverse shaft 5. Both ends of the third shift shaft 83a are passed through a shift guide hole 124 (see 4 ) formed on the partition wall 23 of the right housing 21, and a switch guide hole 125 (see 5 and 6 ) formed on the left end wall 25 of the left housing 22 so as to be slidable in the axial direction (the left-right direction).

The third switching yoke 83b is a plate-shaped body extending in the horizontal direction with the front end portion connected to the third switching shaft 83a (see 2 , 3 and 7 ). A rear end portion of the third switching yoke 83b is formed with a recess that is opened rearward, and the finger portion 74a of the cam member 74 or the outer end of the bent portion of the lower plate 77b is disposed in the recess. Thereby, when the position of the finger portion 74a in the up-down direction coincides with a height position of the third switching yoke 83b, the finger portion 74a is located in the recess of the third switching yoke 83b and can be engaged therewith.

The third shift fork 83c is a plate-like body having a C-shape in a side view, whose outer end portion is branched into two. A base end portion of the third shift fork 83c is connected to the third shift shaft 83a, and an outer end portion of the third shift fork 83c is engaged with a groove formed on the third shift sleeve 37. The third shift fork 83c is connected to the third shift shaft 83a at a position to the left of the third shift yoke 83b (see 10 and 11 ).

The reverse operating arm 83d is connected to the third switching shaft 83a at a position to the right of the third switching yoke 83b (see 10 and 11 ). The outer end portion of the reverse operating arm 83d is inserted into the connecting hole 51a of the reverse drive lever 51 (see 11 and 13 ).

The third shift unit 83 is an integrated structure in which the third shift shaft 83a, the third shift yoke 83b, the third shift fork 83c and the reverse operating arm 83d are coupled to each other, and when movement of the finger portion 74a in the shift direction is transmitted to the third shift yoke 83b, the third shift shaft 83a shifts in the axial direction. Due to the shift of the third shift shaft 83a, the third shift fork 83c moves the third shift sleeve 37 in the axial direction of the input shaft 3, and the engagement relationship of the fifth input gear 34 adjacent to the third shift sleeve 37 is switched. Due to the displacement of the third shift shaft 83a, the reverse operating arm 83d presses an inner surface of the connecting hole 51a to rotate the reverse drive lever 51, and the reverse drive lever 51 moves the reverse idle gear 50 in the axial direction of the reverse shaft 5 (the left direction). Then, the reverse idle gear 50 is located at the same position as the reverse input gear 35 and the reverse counter gear 47 in the axial direction of the reverse shaft 5, and the reverse idle gear 50 is engaged with the reverse input gear 35 and the reverse counter gear 47.

Specifically, in the neutral position of the third shift unit 83, the third shift sleeve 37 is spaced from the fifth input gear 34 to the left without being engaged therewith. Further, the reverse idle gear 50 is spaced from the reverse input gear 35 and the reverse counter gear 47 to the right without being engaged therewith.

When the third shift unit 83 shifts rightward from the neutral position, the third shift sleeve 37 is engaged with the fifth input gear 34. When the third shift sleeve 37 is engaged with the fifth input gear 34, the fifth input gear 34 rotates integrally with the input shaft 3. Then, rotation of the input shaft 3 is transmitted from the fifth input gear 34 to the countershaft 4 via the fifth counter gear 44. This state is a gear ratio of the fifth speed in the transmission gear mechanism 10. When the third shift unit 83 shifts rightward from the neutral position, the outer end of the reverse operating arm 83d is moved into the connection hole 51a without rotating the reverse drive lever 51, and a force that rotates the reverse drive lever 51 is not applied from the reverse operating arm 83d.

When the third shift unit 83 shifts to the left from the neutral position, the outer end of the reverse operating arm 83d presses the inner surface of the connection hole 51a to rotate the reverse drive lever 51. The rotated reverse drive lever 51 presses the reverse idle gear 50, and the reverse idle gear 50 moves to the left on the reverse shaft 5 and meshes with the reverse input gear 35 and the reverse counter gear 47. Then, rotation of the input shaft 3 is transmitted to the countershaft 4 via the reverse input gear 35, the reverse idle gear 50, and the reverse countershaft gear 47. Since the reverse idle gear 50 is interposed, a rotation direction of the countershaft 4 is reversed from the power transmission from the first gear to the fifth gear as described above. The drive wheels are thus driven in a reverse (backward) direction by the gear mechanism 10.

The first switching yoke 81b, the second switching yoke 82b and the third switching yoke 83b, each having a plate shape, are arranged so as to overlap each other in the up-down direction (see 7 ). The groove of the first switching yoke 81b, the groove of the second switching yoke 82b, and the groove of the third switching yoke 83b are arranged in a straight line. Specifically, they are arranged in an order of the first switching yoke 81b, the second switching yoke 82b, and the third switching yoke 83b from below. The finger portion 74a of the cam member 74 moves in the grooves of the three switching yokes 81b, 82b, and 83b arranged in the straight line in accordance with the movement of the switching and selecting shaft 70 in the up-down direction due to the selecting operation of the passenger. Then, the finger portion 74a is selectively engaged with the groove in which the finger portion 74a is located to move the switching unit in the axial direction in accordance with a rotation of the switching and selecting shaft 70 due to the switching operation of the passenger. Among the three switching yokes 81b, 82b and 83b, the bent portions (the front end portion) of the upper plate 77a and the lower plate 77b of the locking plate 77 are each arranged with respect to the remaining two recesses in which the finger portion 74a is absent. The shift yoke in which the detent plate 77 is present in the recess is engaged with the detent plate 77 and restricted from moving in the left-right direction (movement in the shift direction). Therefore, when the shift and select shaft 70 is operated in the shift direction, only one of the three shift yokes 81b, 82b and 83b moves together with the finger portion 74a, the other two being prevented from moving and being held in the above-described neutral positions, respectively.

When the shift lever operated by the passenger is in a neutral position in both the select direction and the shift direction, each of the first shift unit 81, the second shift unit 82, and the third shift unit 83 is in the neutral position in the shift direction, and rotation of the input shaft 3 is not transmitted to the countershaft 4. Thus, the driving force is not transmitted to the final driven gear 60. In the neutral position of the shift lever, the finger portion 74a of the cam member 74 is biased by a spring to be at a position corresponding to the recess of the second shift yoke 82b in the up-down direction (the select direction). Therefore, when the shift lever is shifted directly from the neutral position, the second shift unit 82 moves in the shift direction to select the third gear or the fourth gear.

When the shift lever is operated from the neutral position to one side in the selection direction, the shift and select shaft 70 moves downward and the finger portion 74a of the cam member 74 comes to a position corresponding to the recess of the first shift yoke 81b in the up-down direction (the selection direction). When the shift lever is switched in this state, the first switching unit 81 moves in the switching direction to select the first gear or the second gear.

When the shift lever is operated from the neutral position to the other side in the selection direction, the shift and select shaft 70 moves upward and the finger portion 74a of the cam member 74 comes to a position corresponding to the recess of the third shift yoke 83b in the up-down direction (the selection direction). When the shift lever is shifted in this state, the third shift unit 83 moves in the shift direction to select the fifth gear or vice versa (reverse).

As described above, when the shift stage of the transmission gear mechanism 10 is selected using the switching device 7 and the internal switching mechanism 8 and the countershaft 4 is rotated by the driving force of the input shaft 3, the rotation from the final drive gear 45 on the countershaft 4 is transmitted to the final driven gear 60, and the input shaft is rotated. When moving forward in the first gear to the fifth gear, the final driven gear 60 rotates in a forward direction indicated by the arrows FW in the 2 and 3 is shown.

The transmission 2 has a lubricating structure that circulates lubricating oil and supplies the lubricating oil to each section in the transmission case 20. As shown in 2 and 3 shown, within the transmission case (the left case 22), the transmission gear mechanism 10 and the internal shift mechanism 8 are arranged at an upper portion on the front side, and the differential device 6 (the final driven gear 60) is arranged at a lower portion on the rear side. A lubricating oil inlet 22b (see 1 , 5 and 6 ) opened to the left is provided at the rear of the left case 22, and lubricating oil is injected into the transmission case 20 so that a liquid surface position when the engine is stopped is near the lubricating oil inlet 22b. Thus, an oil reservoir is formed at a lower portion of the transmission case 20. In this state, a part of each of the transmission gear mechanism 10 and the differential device 6 is immersed in the lubricating oil stored in the lower portion of the transmission case 20.

When driving or starting the engine 1, the transmission gear mechanism 10 is rotated, and the lubricating oil in the transmission case 20 is circulated due to the operation of the gears or the like in the transmission case 20. Specifically, the lubricating oil stored in the lower portion of the transmission case 20 is brought up and moved upward due to the rotation of the large-diameter final driven gear 60 located at the rear lower portion in the transmission case 20. The rear wall portion 24c of the peripheral wall 24 extends obliquely upward above the final driven gear 60 (see 8th ). The lubricating oil that is carried upward by the final driven gear 60 rotating in the forward direction FW impinges on the rear wall portion 24c and thus is distributed or flows along the rear wall portion 24c. The lubricating oil that is distributed or flows in the transmission case 20 lubricates the transmission gear mechanism 10 and the internal switching mechanism 8 and falls downward and returns to the lower portion of the transmission case 20.

A position where the final driven gear 60 is arranged in the transmission case 20 is a right rear position in the left space and on the right end side in the left case 22 near the partition wall 23, and most of the transmission gear mechanism 10 is located to the left of the final driven gear 60. Therefore, the lubricating structure of the transmission 2 of the present embodiment includes an oil groove 9 that collects the lubricating oil carried up by the final driven gear 60 and supplies the lubricating oil to each portion of the transmission gear mechanism 10 to be lubricated. A shape of the individual oil groove 9 is shown in 14 to 16 shown.

The oil groove 9 is located at the upper portion near the upper wall portion 24a in the gear housing 20 (see 2 to 5 ). The oil groove 9 forms an oil passage which transversely traverses the left housing 22 from a collection section 90 located above the final driven gear 60 to a supply end section 95 adjacent the left end wall 25 (see 10 to 13 ). In the oil groove 9, the lubricating oil flows from the collecting portion 90 to the supply end portion 95, with the right side where the collecting portion 90 is located being an upstream side and the left side where the supply end portion 95 is located being a downstream side. Each portion of the oil groove 9 has a groove-like cross-sectional shape surrounded by a bottom wall and side walls protruding upward from edges of the bottom wall, and an upper surface side (upper portions of the side walls) of the oil groove 9 is open.

As in 14 and 15 As shown, the oil groove 9 includes a collecting portion 90 located on the most upstream side, an inflow portion 91 continuous with the collecting portion 90, a first oil passage 92 extending continuously with the inflow portion 91, a second oil passage 93 branching from the inflow portion 91, a merging portion 94 merging the first oil passage 92 and the second oil passage 93, and the supply end portion 95 which is an end portion on the downstream side continuous with the merging portion 94. A penetrating portion 96 penetrating in the up-down direction is formed in a region surrounded by the first oil passage 92, the second oil passage 93, and the merging portion 94. In other words, the first oil passage 92 and the second oil passage 93 are branched with the penetrating portion 96 interposed therebetween. The oil groove 9 has a penetrating portion 96 provided between the first oil passage 92 and the second oil passage 93, and the penetrating portion 96 serves as a through hole communicating with an upper side and a lower side of the oil groove 9.

The collecting portion 90 projects rearward with respect to the inflow portion 91 and the first oil passage 92, and has a flat bottom wall portion 90a and a right side wall portion 90b and a left side wall portion 90c projecting upward from the left and right edges of the bottom wall portion 90a. A rear end of the collecting portion 90 is a collecting port 90d opened between the right side wall portion 90b and the left side wall portion 90c. The bottom wall portion 90a is arranged at a position near an outer peripheral portion of the final driven gear 60. As shown in 8th Thus, as shown in FIG. 1, the bottom wall portion 90a is disposed at a position above the final driven gear 60 and near the outer peripheral portion thereof, and as shown in FIG. 12 As shown, at least a part of the bottom wall portion 90a is arranged at the same position as the final driven gear 60 in the left-right direction. Then, the lubricating oil is carried up by the final driven gear 60 rotating in the forward direction FW, flows into the collecting portion 90 from an opening portion on the upper side of the collecting opening 90d and the collecting portion 90.

The inflow portion 91 extends leftward from the front of the collecting portion 90. The bottom wall of the inflow portion 91 includes a curved bottom wall portion 91a located forward of the bottom wall portion 90a of the collecting portion 90, a flat bottom wall portion 91b extending leftward from the curved bottom wall portion 91a, a curved bottom wall portion 91c located at a front edge portion of the flat bottom wall portion 91b, and an inclined bottom wall portion 91d continuous with a left side of the flat bottom wall portion 91b.

The curved bottom wall portion 91a is formed continuously with the bottom wall portion 90a and has an arc shape whose downward projection value increases toward the front side (see 5 and 8th ). The arc shape of the curved bottom wall portion 91a extends along the outer circumference of the final driven gear 60, which is located directly under the curved bottom wall portion 91a. In other words, the curved bottom wall portion 91a is a clearance portion that arranges the oil groove 9 close to the final driven gear 60 without interference, and a space under the curved bottom wall portion 91a serves as an arrangement space of the final drive gear 60.

The flat bottom wall portion 91b is continuous with a deepest portion of the curved bottom wall portion 91a and is located deeper than the bottom wall portion 90a of the collecting portion 90 and the curved bottom wall portion 91a (see 4 and 5 ). A drip hole 100 is formed through the flat bottom wall portion 91b. The drip hole 100 is formed at a position near a front right end of the flat bottom wall portion 91b, and the first counter gear 40 is located near a position under the drip hole 100 (see 12 and 13 ). The flat bottom wall portion 91b is located higher than the lubricating oil inlet 22b. Therefore, all the lubricating oil can drip down the flat bottom wall portion 91b through the drip hole 100.

The curved wall portion 91c is formed continuously with the front portion of the flat bottom wall portion 91b and has an arc shape extending upward toward the front side (see 5 and 15 ). The arc shape of the curved bottom wall portion 91c extends along the outer peripheral shape of the first counter gear 40 and the first shift sleeve 46 (including the reverse counter gear 47) which are located directly below the curved bottom wall portion 91c. In other words, the curved bottom wall portion 91c is a clearance portion that arranges the oil groove 9 near the first counter gear 40 and the first shift sleeve 46 without interference, and a space under the curved wall portion 91c serves as an arrangement space of the first counter gear 40 and the first shift sleeve 46. The inclined bottom wall portion 91d, which is formed continuously with the left end of the flat bottom wall portion 91b, has an inclined shape that gradually flattens (projects upward) to the left of the flat bottom wall portion 91b and is continuous with the first oil passage 92. The inclined bottom wall portion 91d is located on the right side of the shaft support portion 29 of the left housing 22 and reaches a position higher than the shaft support portion 29. Thus, the inflow portion 91 (the flat bottom wall portion 91b) is located on the right side of the shaft support portion 29 in the left-right direction and bulges downward in the up-down direction to one side of the shaft support portion 29. Therefore, the inflow portion 91 has a portion lower than the collecting portion 90 and the first oil passage 92 and functions as a reservoir that stores the lubricating oil.

Side walls of the inflow portion 91 include a right side wall portion 91e extending forward continuously with the right side wall portion 90b of the collecting portion 90, a front side wall portion 91f extending leftward from a front end of the right side wall portion 91e, a partition wall portion 91g continuous with a left side of the front side wall portion 91f, and a rear side wall portion 91h extending leftward from the left side wall portion 90c of the collecting portion 90. Upper ends of the right side wall portion 90b, the partition wall portion 91g, the left side wall portion 90c, and the rear side wall portion 91h are formed at substantially the same height. In contrast, as shown in 8th shown, upper ends of the right side wall portion 91e and the front side wall portion 91f are formed higher along the inner surface of the peripheral wall 24.

Further, a rectifying rib 91i is provided by extending a left side wall portion 90c of the collecting portion 90 forward. The lubricating oil flowing into the collecting portion 90 can be smoothly guided to the inflow portion 91 through the flow regulating rib 91i and the right side wall portion 91e. In particular, due to the rectifying rib 91i, a flow of the lubricating oil can be directed to reliably guide the lubricating oil to the vicinity of the drip hole 100, and a reverse flow from the inflow portion 91 to the collecting portion 90 is prevented to form a flow to the first oil passage 92.

The bottom wall portion 90a of the collecting portion 90 is a position near the outer periphery of the final driven gear 60 and easily receives the lubricating oil carried up by the final driven gear 60 (see 8th ). The curved bottom wall portion 91a of the inflow portion 91 has a downward projection amount which increases toward the front side along the outer circumference of the final driven gear 60 (see 8th ). The right side wall portion 90b and the right side wall portion 91e are designed to have heights in the up-down direction that gradually increase and are provided closer to the inner surface of the peripheral wall 24 as it extends from the back to the front, with a front end portion connected to the front side wall portion 91f being the highest (see 5 and 8th ). Therefore, the most upstream portion of the oil groove 9 from the collecting opening 90d to the front side wall portion 91f has a triangular shape extending in a side view from the rear to the front. A space having a substantially triangular shape in a side view surrounded by the upper wall portion 24a, the rear wall portion 24c and the final driven gear 60 is located at an upper side of a rear portion of the left housing 22, and the most upstream portion of the oil groove 9 is in the space with good space utilization (see 8th ).

An interval between the front side wall portion 91f and the rear side wall portion 91h in the front-rear direction is widened in the inflow portion 91. On the other hand, the partition wall 91g is located closer to the rear wall portion 91h than the front wall portion 91f and narrows in a front-rear space of the inflow portion 91. The partition wall portion 91g has an inclined part closer to the rear side wall portion 91h to the left side, and a notch 91j is formed on the inclined part. Viewed from the inflow portion 91 side, the notch 91j is opened to the obliquely left front side. The notch 91j is a rectangular opening cut downward from the upper end of the partition wall portion 91g.

The partition wall portion 91g forms a boundary between the inflow portion 91 and the second oil passage 93 which will be described later. The lubricating oil in the inflow portion 91 is divided into a flow that flows to the first oil passage 92 without passing through the notch 91j and a flow that passes through the notch 91j and flows to the second oil passage 93. Of these two oil passages, the first oil passage 92 will be described first.

The first oil passage 92 has a rear oil passage portion 92a extending leftward continuously with the inflow portion 91 and a left oil passage portion 92b extending forward from a left end portion of the rear oil passage portion 92a and reaching the merging portion 94. The rear oil passage portion 92a is located rearward of the penetrating portion 96, with the left oil passage portion 92b being located leftward of the penetrating portion 96.

The bottom wall portion 92c forming the bottom wall of the first oil passage 92 is continuous with the left end portion which is the highest of the inclined bottom wall portion 91d of the inflow portion 91 and is located higher than the flat bottom wall portion 91b. Further, the bottom wall portion 92c is located higher than the bottom wall portion 90a of the collecting portion 90. As shown in 7 As shown, the bottom wall portion 92c is located higher than the shaft support portion 29 of the left housing 22, and the first oil passage 92 is arranged to pass above the shaft support portion 29. The bottom wall portion 92c has a continuous shape without a step from the rear oil passage portion 92a to the left oil passage portion 92b.

The side wall of the first oil passage 92 includes an inner peripheral side wall portion 92d located on an inner peripheral side surrounding the penetration portion 96, and an outer peripheral side wall portion 92e forming an outer edge (a rear edge) portion of the first oil passage 92. In the rear oil passage portion 92a, the inner peripheral side wall portion 92d is erected from a front end of the bottom wall portion 92c and extends in the left-right direction continuously with the partition wall portion 91g of the inflow portion 91. A height position of an upper end of the inner wall portion 92d is substantially the same as the upper end of the partition wall portion 91g and is substantially the same as an upper end of the outer peripheral side wall portion 92e. As shown in 7 , an upper end of the inner peripheral side wall portion 92d is separated from the rear wall portion 24c of the left case 22, and the lubricating oil flowing through a space between the upper end of the inner peripheral side wall portion 92d and the rear wall portion 24c can be taken in by the rear oil passage 92a. In the rear oil passage portion 92a, the outer peripheral side wall portion 92e is erected from a rear end of the bottom wall portion 92c and extends in the left-right direction continuously with the rear side wall portion 91h of the inflow portion 91. A height position of an upper end of the outer peripheral side wall portion 92e is substantially the same as that of the upper end of the rear side wall portion 91h and is substantially the same as that of the upper end of the inner peripheral side wall portion 92d. As shown in 7 As shown, the upper end of the outer peripheral side wall portion 92e is located near the rear wall portion 24c of the left housing 22 and can reduce an amount of the lubricating oil passing through an upper space of the rear oil passage portion 92a and can accommodate more lubricating oil in the rear oil passage portion 92a and reduce an amount of the lubricating oil passing over the outer peripheral side wall portion 92e from the rear oil passage portion 92a and leaking to the rear side. Furthermore, by setting the extending directions of the inner peripheral side wall portion 92d and the outer peripheral side wall portion 92e, lubricating oil from the inflow portion 91 can smoothly flow to the rear oil passage portion 92a. Since the rear side wall portion 91h and the outer peripheral side wall portion 92e are close to the rear wall portion 24c of the left housing 22 and are arranged along the rear wall portion 24c, the inflow portion 91 and the first oil passage 92 are arranged at the rearmost position (an installation limit) in the left housing 22 (see 7 and 10 ). The rear oil passage portion 92a is disposed above the shaft support portion 29 in a manner to pass between the switching device 7 and the rear wall portion 24c.

In the left oil passage portion 92b, the inner peripheral side wall portion 92d and the outer peripheral side wall portion 92e each extend from the rear oil passage portion 92a diagonally to the oblique left front side. In the left oil passage portion 92b, the inner peripheral side wall portion 92d is erected upward from a right end of the bottom wall portion 92c, and the outer peripheral side wall portion 92e is erected upward from the left end of the bottom wall portion 92c. Near a left end of the left housing 22, the rear wall portion 24c is inclined to protrude forward (toward the front wall portion 24b) toward the left side, and the outer peripheral side wall portion 92e of the left oil passage portion 92b has a shape corresponding to the inclination of the rear wall portion 24c (see 10 ). That is, the left housing 22 is tapered toward the left end, and the outer peripheral side wall portion 92e of the left oil passage portion 92b is bent from the outer peripheral side wall portion 92e of the rear oil passage portion 92a in a shape along an inner surface of the rear wall portion 24c. Further, as in 2 and 16 , the height position of the upper end of the outer peripheral side wall portion 92e of the left oil passage portion 92b is lower than a front side (left side) thereof. In the left oil passage portion 92b, a distance of the inner peripheral side wall portions 92d to the outer peripheral side wall portion 92e increases toward the front side. The left oil passage portion 92b is bent with respect to the rear oil passage portion 92a, but since a bending angle thereof is kept small and the distance between the inner peripheral side wall portion 92d and the outer peripheral side wall portion 92e is gradually increased, the lubricating oil can smoothly flow from the rear oil passage portion 92a to the left oil passage portion 92b.

As in the 14 and 16 As shown, at a front end portion of the left side oil passage portion 92b, a plate-shaped rectifying rib 92f is provided which projects upward from the bottom wall portion 92c. The rectifying rib 92f extends in the left-right direction and partially closes between the inner peripheral side wall portion 92d and the outer peripheral side wall portion 92e. A height position of an upper end of the rectifying rib 92f is a height position lower than that of the upper end of the inner peripheral side wall portion 92d but substantially the same as that of the upper end of the outer peripheral side wall portion 92e, and serves as an overflow plate for storing the lubricating oil in the collecting portion 90, the inflow portion 91, and the first oil passage 92. The height position of the upper end of the rectifying rib 92f is set higher than the height of a lower end portion of the notch 91j (see 16 ). Between both end portions of the rectifying rib 92f, the inner peripheral side wall portion 92d, and the outer peripheral side wall portion 92e, intervals are provided, respectively. Through these intervals, the lubricating oil flows from the first oil passage 92 to the merging portion 94. Specifically, a distance between the rectifying rib 92f and the outer peripheral side wall portion 92e is set larger so that the lubricating oil easily flows from a portion along the outer peripheral side wall portion 92e to the supply end portion 95 side (a left side of the merging portion 94) of the merging portion 94.

Next, the second oil passage 93 will be described. The second oil passage 93 is an oil passage connecting the inflow portion 91 and the merging portion 94, and the lubricating oil flows from the inflow portion 91 into the second oil passage 93 through the notch 91j formed on the partition wall portion 91g. As shown in 12 As shown, when the oil groove 9 is viewed from above, the second oil passage 93 extends from the inflow portion 91 to the substantially oblique left front side on a side opposite to a side on which the collecting portion 90 is arranged. The notch 91j, which is a connecting portion of the second oil passage 93 and the inflow portion 91 and is located at a starting end portion of the second oil passage 93, is open toward an extending direction of the second oil passage 93. Since the partition wall portion 91g on which the notch 91j is formed is substantially perpendicular to the extending direction of the second oil passage 93 is formed, since the second oil passage 93 extends in a flow direction of the lubricating oil flowing through the notch 91j, the lubricating oil can flow smoothly in the second oil passage 93.

The second oil passage 93 has an upstream side oil collecting tank portion 93a located at the front of the partition wall portion 91g of the inflow portion 91, and a front oil passage portion 93b located at the downstream side connecting the oil collecting tank portion 93a and the merging portion 94. The oil collecting tank portion 93a is located to the right of the penetrating portion 96, and the front oil passage portion 93b is located in front of the penetrating portion 96.

A bottom wall of the second oil passage 93 includes a lower bottom wall portion 93c located adjacent to the front of the partition wall portion 91g, a curved bottom wall portion 93d located in front of the lower bottom wall portion 93c, an upper bottom wall portion 93e located to the left and in front of the curved bottom wall portion 93d, and a transitional bottom wall portion 93f connecting the curved bottom wall portion 93d and the upper bottom wall portion 93b. The lower bottom wall portion 93c and the curved bottom wall portion 93d form the bottom wall of the oil collecting tank portion 93a, and the upper bottom wall portion 93c forms the bottom wall of the front oil passage portion 93b. The transitional bottom wall portion 93f forms a bottom wall of a boundary portion between the oil collecting tank portion 93d and the front oil passage portion 93b.

The lower bottom portion 93c has a flat shape. The lower bottom wall portion 93c is located at the lowest position of the bottom wall of the oil groove 9 (see 4 , 5 and 16 ). The upper bottom wall portion 93e has an arc shape which is gradually bent downward from a front edge side to a rear edge side (see 7 ). The upper bottom wall portion 93e is located higher than the lower bottom wall portion 93c and lower than the bottom wall portion 92c of the first oil passage 92 (see 16 ) .

The curved bottom wall portion 93d is an arc portion having a shape having an upward projection rising from the lower bottom wall portion 93c toward the front side (see 4 and 5 ). The arc shape of the curved bottom wall portion 93d extends along the outer peripheral shapes of the reverse counter gear 47, the second counter gear 41, and the third counter gear 42.

In other words, the curved bottom wall portion 93d is a clearance portion that smoothly arranges the oil groove 9 near the reverse counter gear 47, the second counter gear 41, and the third counter gear 42, and a space below the curved bottom wall portion 93d serves as an arrangement space for the reverse counter gear 47, the second counter gear 41, and the third counter gear 42. The transition bottom wall portion 93f is an arc portion based on the same arc shape as the curved bottom wall portion 93d, and is a portion that gradually transitions from the arc shape of the upper bottom wall portion 93e to the arc shape of the curved bottom wall portion 93d. The arc shape of the upper bottom wall portion 93e and the arc shape of the curved bottom wall portion 93d are formed concentrically with an axis of the countershaft 4 as a center axis, and the arc shape of the upper bottom wall portion 93e is formed with a smaller diameter.

A drip hole 101 is formed through the curved bottom wall portion 93d, and a drip hole 102 is formed through the transitional bottom wall portion 93f. The drip hole 101 is formed near a center of the curved bottom wall portion 93d, and the second counter gear 41 is located below the drip hole 101 (see 12 and 13 ). The drip hole 102 is located at the front left side of the drip hole 101 and the third counter gear 42 is located under the drip hole 102 (see 12 and 13 ). A drain hole 105 is formed through the lower bottom wall portion 93c. Below the drain hole 105, there are no gears or the like constituting the gear mechanism 10. A region between the third counter gear 42 and the fourth counter gear 43 on the counter shaft 4 is located below the upper bottom wall portion 93e.

Side walls of the second oil passage 93 include an inner peripheral side wall portion 93g located on an inner peripheral side surrounding the penetrating portion 96, and an outer peripheral side wall portion 93h forming an outer edge (a front edge) of the second oil passage 93. In the oil collecting tank portion 93a, the inner peripheral side wall portion 93g has a shape that rises upward from an end edge at the penetrating portion 96 (a left end edge) of the lower bottom wall portion 93c, extends forward from the inner peripheral side wall portion 92d, and extends from the oil passage 93a. section 93b is bent to the left. In the front oil passage section 93b, the inner peripheral side wall section 93g has a shape that rises upward from an end edge at the penetration section 96 of the upper bottom wall section 93e (a rear end edge) and extends in the left-right direction. A height of an upper end portion of the inner peripheral side wall section 93g is lower than the bottom wall section 92c of the first oil passage 92. The outer peripheral side wall section 93h has a shape that rises upward from the front edges of the bent bottom wall section 93d and the upper bottom wall section 93e in the oil collecting tank section 93a and in the front oil passage section 93b. A part of the outer peripheral side wall section 93h forms an inclined portion 93i that is inclined so as to extend leftward toward the front. The inclined portion 93i extends to the obliquely left front side from a front portion of the oil collecting tank portion 93a to a front portion of the front oil passage portion 93b, and due to a shape of the inclined portion 93i, a distance between the inner peripheral side wall portion 93g and the outer peripheral side wall portion 93h increases to the left side in the front oil passage portion 93b.

A plate-shaped rectifying rib 93j protruding upward from the upper bottom wall portion 93e is provided at a left end portion of the front oil passage portion 93b. The rectifying rib 93j extends in the front-rear direction and partially closes the inner peripheral side wall portion 93g and the outer peripheral side wall portion 93h. A protrusion amount that the rectifying rib 93j protrudes upward is smaller (less) than the adjacent inner peripheral side wall portion 93g and outer peripheral side wall portion 93h. A clearance is between the rectifying rib 93j and the outer peripheral side wall portion 93h. The lubricating oil flows from the second oil passage 93 through the gap and an upper portion of the rectifying rib 93j to the merging portion 94. The rectifying rib 93j prevents the lubricating oil from flowing from the merging portion 94 to the second oil passage 93.

The merging portion 94 is located in front of the left oil passage portion 92b of the first oil passage 92 and to the left of the front oil passage portion 93b of the second oil passage 93. The bottom wall of the merging portion 94 has an upper bottom wall portion 94a located adjacent to a left side of the upper bottom wall portion 93e of the second oil passage 93 (with the rectifying rib 93j therebetween) and a lower bottom wall portion 94b located on the left side of the upper bottom wall portion 94a.

The upper bottom wall portion 94a is located at a height slightly higher than a front end of the upper bottom wall portion 93e of the second oil passage 93, and is located lower than the bottom wall portion 92c of the first oil passage 92 (see 16 ). A drip hole 103 and a drip hole 104 are formed through the upper bottom wall portion 94a. The drip hole 103 is formed at a position on the right side of the upper wall portion 94a, and the fourth counter gear 43 is located under the drip hole 103 (see 12 and 13 ). The drip hole 104 is formed on the left side of the drip hole 103 and the fifth counter gear 44 is located under the drip hole 104 (see 12 and 13 ). The upper bottom wall portion 94a is a flat surface inclined to have a deeper front side.

The lower bottom wall portion 94b is formed at a position lower than the upper bottom wall portion 94a. Like the upper bottom wall portion 94a, the lower bottom wall portion 94b is inclined to have a lower front side. Thus, the lower bottom wall portion 94b is lower than the upper bottom wall portion 94a and the bottom wall portion 92c, so that the lubricating oil can easily flow therein, and the lubricating oil flowing therein can be smoothly supplied to the supply end portion 95. A surface between the fifth counter gear 44 and the bearing 4b on the counter shaft 4 is located under the lower bottom wall portion 94b.

Side walls of the union portion 94 include a left side wall portion 94c erected upward from a left end edge of the lower bottom wall portion 94b, connected to a front end of the outer peripheral side wall portion 92e of the first oil passage 92, and extending forward, a front side wall portion 94d erected upward from a front end edge of the upper bottom wall portion 94a or from the front end edge of the lower bottom wall portion 94b, connected to a left end of the outer peripheral side wall portion 93h of the second oil passage 93, and extending leftward, and an inner peripheral side wall portion 94e erected upward from a rear end edge of the upper bottom wall portion 94a and connecting the inner peripheral side wall portion 92d and the inner peripheral side wall portion 93g. Height positions of the upper ends of the side walls of the union portion 94 are at the same heights. position as upper ends of the side walls of the second oil passage 93.

A rectifying rib 94f is provided on the lower bottom wall portion 94b of the merging portion 94. The rectifying rib 94f extends forward from the vicinity of a left end portion of the flow regulating rib 92f provided in the left oil passage 92b. A front end of the rectifying rib 94f is located near the front side wall portion 94d while ensuring a clearance from the front side wall portion 94d so that the lubricating oil can flow. The lubricating oil which has passed between the left end portion of the rectifying rib 92f and the outer peripheral side wall portion 92e in the first oil passage 92 and flowed into the merging portion 94 passes between the rectifying rib 94f and the left side wall portion 94c and flows to the supply end portion 95. On the other hand, the lubricating oil which enters the merging portion 94 from the second oil passage 93 passes between the front end of the rectifying rib 94f and the front wall portion 94d and flows to the supply end portion 95. The rectifying rib 94f is constructed to have a gradually decreasing distance from the left side wall portion 94c to the front side (see 12 and 14 ) and allows the lubricating oil to flow smoothly from either the first oil passage 92 or the second oil passage 93 to the supply end portion 95 side. As described above, due to the rectifying rib 94f dividing an interior of the merging portion 94, the lubricating oil passing through the first oil passage 92 and the lubricating oil passing through the second oil passage 93 are smoothly guided to the supply end portion 95 without interfering with each other. The rectifying rib 94f is set to a height lower than that of the left side wall portion 94c, and in a case where a large amount of the lubricating oil flows into the merging portion 94, the lubricating oil can pass over the rectifying rib 94f.

The feed end portion 95 projects leftward from a left edge portion of the front portion of the merging portion 94. A bottom wall portion 95a constituting a bottom wall of the feed end portion 95 has a height such that a rear end portion thereof is continuous with the lower bottom wall portion 94b, and has an inclined shape that becomes smaller toward the front.

Side walls of the supply end portion 95 include a rear side wall portion 95b extending leftward from a front end of the left side wall portion 94c, a front side wall portion 95c rising upward from a front edge of the bottom wall portion 95a, an end wall portion 95d bent forward from a left end of the rear side wall portion 95b, and an end wall portion 95e bent forward from a left end of the front side wall portion 95c. An end portion opening 95f opened to the left is formed between the end wall portion 95d and the end wall portion 95e (between the end wall portion 95d and the front side wall portion 95c). The end wall portion 95e has an inclined shape protruding downward toward the front side along the inclination of the bottom wall portion 95a (see 4 ). The end wall portion 95d projects slightly to the left of the end wall portion 95e.

The penetrating portion 96 is a hole formed to penetrate the oil groove 9 in the up-down direction, and is a vertically opened space defined by the inner peripheral side wall portion 92d of the first oil passage 92, the inner peripheral side wall portion 93g of the second oil passage 93, and the inner peripheral side wall portion 94e of the merging portion 94 in the plan view of the oil groove 9 shown in 12 and the like. The first oil passage 92 and the second oil passage 93 have different positions in the up-down direction and the first oil passage 92 is located at the top and the second oil passage 93 is located below (see 7 and 16 ). Accordingly, positions of the inner peripheral side wall portion 92d and the inner peripheral side wall portion 93g are also vertically spaced from each other, and a range of the penetrating portion 96 in the up-down direction is from the upper end of the inner peripheral side wall portion 92d of the first oil passage 92 to a lower end of the inner peripheral side wall portion 93g of the second oil passage 93.

As in 11 As shown, a support projection 96a projecting toward an inner side of the penetrating portion 96 is provided near a boundary between the inner peripheral side wall portion 94e and the inner peripheral side wall portion 92d. The support projection 96a is a cantilever-like projection having an outer end as a free end and is elastically deformable in the front-rear direction with a base thereof as a fulcrum.

As in 11 As shown, the oil groove 9 further comprises a hook portion 97 and a hook portion 98. The hook portion 97 is a hook-shaped The hook portion 98 is a hook-like portion protruding leftward from the left side wall portion 90c of the collecting portion 90. The hook portion 98 is a hook-like portion protruding leftward from a wall portion extending from the right side wall portion 91e of the inflow portion 91.

As in 6 , in the left housing 22, a surface parallel to the fitting surface 22a is provided at positions near the fitting surface 22a, respectively, and an engaging portion 27 with which the hook portion 97 is engaged and an engaging portion 28 with which the hook portion 98 is engaged are formed on these parallel surfaces, respectively. The engaging portions 27 and 28 are holes formed in the left housing 22 and opened to the right. When the hook portions 97 and 98 are inserted into the engaging portions 27 and 28, hook shapes thereof are elastically deformed, and the hook portions 97 and 98 are engaged with the engaging portions 27 and 28, so that the oil groove 9 is held in the left housing 22. In a state where the oil groove 9 is attached to the left housing 22, the penetrating portion 96 of the oil groove 9 is located under the opening 26 formed in the upper wall portion 24a. Further, the support projection 96a protruding to an interior of the penetrating portion 96 comes into contact with an outer surface of the shaft support portion 29 in the left housing 22 to stabilize the oil groove 9, and as will be described later, the end wall portion 95d on the left end side of the supply end portion 95 is fitted into a connection recess 116 of the left end wall 25 to stabilize the oil groove 9. The surfaces on which the engaging portions 27 and 28 are formed are respectively arranged at positions near the fitting surface 22a in the left-right direction, and after the left housing 22 and the right housing 21 are coupled, the oil groove 9 is prevented from moving rightward by the right housing 21 and the hook portions 97 and 98 cannot fall out of the engaging portions 27 and 28.

The connection recess 116, which communicates with the support recess 111 supporting the bearing 3b, is formed on the left end wall 25 of the left housing 22 (see 6 and 9 ). The connection recess 116 is a recess extending rearward and upward from the support recess 111 and has a groove shape opened to the right. When the hook portions 97 and 98 are engaged with the engaging portions 27 and 28 to mount the oil tray 9 in the left housing 22, the end wall portion 95d and the end wall portion 95e on the left end side of the supply end portion 95 are fitted into the connection recess 116. Since the end wall portion 95e conforms to a shape of the connecting groove 116 and closes the opening on the right side of the connecting groove 116, and the end wall portion 95d on the rear side protrudes to the left of the end wall portion 95e on the front side (the end wall portion 95e has a larger distance from an inner rear wall of the connecting groove 116), the lubricating oil leaking from the end portion opening 95f easily flows to the side of the support groove 111 through the distance between the end wall portion 95e and the connecting groove 116.

In the input shaft 3 supported by the bearing 3b, an axial hole 3c running in the axial direction (see 2 ) and radial holes (not shown) extending radially from the axial hole 3c and communicating with the support positions of the gears and the shift sleeves on the input shaft 3, respectively. The axial hole 3c is open to a left end of the input shaft 3 (see 2 ), and in a state where the left housing 22 is mounted, a shaft end opening of the axial hole 3c faces an inner side of the support recess 111 (see 9 ). The axial hole 3c is thus in communication with the support groove 111 and the connecting groove 116. Therefore, the lubricating oil flowing from the end portion opening 95f of the oil groove 9 into the connecting groove 116 is guided into the axial hole 3c of the input shaft 3 and supplied to the shift gears and the shift sleeves on the input shaft 3 through the radial holes. The lubricating oil supplied into the support groove 111 lubricates and passes through the bearing 3b and flows into the left space of the transmission case 20, but an amount of the lubricating oil flowing through the bearing 3b is limited by a lubricating oil introducing member 117 arranged in the support groove 111 (see 9 ). The lubricating oil introducing member 117 includes a disk portion covering a part of a side surface of the bearing 3b and a tubular portion protruding from the disk portion and inserted into the axial hole 3c, and is a member that restricts a flow to the bearing 3b with the disk portion and introduces the lubricating oil into the axial hole 3c with the tubular portion.

An axial hole 4c (see 2 , 3 , 7 , 8th and 9 ) extending in the axial direction and radial holes (not shown) extending radially from the axial hole 4c and communicating with the support positions of the gears and the shift sleeve on the countershaft 4, respectively, are also formed in the countershaft 4. The axial hole 4c is open at both ends of the countershaft 4. The lubricating oil is supplied to the shift gears and the shift sleeve on the countershaft 4 through the radial holes.

When the transmission 2 is assembled, the transmission gear mechanism 10 and the internal switching mechanism 8 are previously assembled on the side of the right case 21 with the left side facing up. Then, in a state where the oil tray 9 is assembled in the left case 22, the left case 22 is assembled to cover the right case 21 from above.

When assembling the left housing 22, the oil groove 9 in the left housing 22 is not visually recognized. Therefore, when the left housing 22 is assembled in a state displaced from a predetermined position with respect to the right housing 21, the oil groove 9 may come into contact with the structure attached to the right housing 21. Since a part of the oil groove 9 from the front oil passage portion 93b to the merging portion 94 and the supply end portion 95 enters a narrow space between the first shift shaft 81a, the second shift shaft 82a, and the countershaft 4, contact and collision are likely to occur particularly at this part. In particular, the outer ends of the first shift shaft 81a and the second shift shaft 82a may come into contact with the vicinity of the front oil passage portion 93b.

The front oil passage portion 93b of the oil groove 9 includes the inclined portion 93i on the outer peripheral side wall portion 93h. The inclined portion 93i has a shape inclined with respect to the axial directions of the first switching shaft 81a and the second switching shaft 82a (the left-right direction). Therefore, when the outer end of the first switching shaft 81a or the second switching shaft 82a is in contact with the inclined portion 93i, the inclined portion 93i functions as a guide portion that guides the assembly of the left housing 22 without difficulty. In particular, since the inclination of the inclined portion 93i increases a forward projection toward the left side, a backward force component is generated with respect to the oil groove 9 when the left housing 22 moves toward the right housing 21 in a state where the front end of the first shift shaft 81a or the second shift shaft 82a is in contact with the inclined portion 93i. Then, the oil groove 9 and the left housing 22 are guided to corresponding positions in the front-rear direction. This makes it possible to prevent damage to the components and improve assembly workability. Thus, the force can be released by the inclined portion 93i, and it is possible to prevent collision or hooking of the oil groove 9 made of a resin material, thereby not damaging the oil groove 9.

When the assembly of the left housing 22 with the right housing 21 is completed, the oil groove 9 is accommodated in a peripheral space of the transmission gear mechanism 10 and the internal switching mechanism 8. As shown in 2 , 3 and 7 As shown, the part of the oil groove 9 from the front oil passage portion 93b to the merging portion 94 and the supply end portion 95 arranged in front of the penetrating portion 96 is located above the countershaft 4 and below the first shift shaft 81a and the second shift shaft 82a. Specifically, the front oil passage portion 93b is arranged between the second shift fork 82c and the shaft support portion 29 in the front-rear direction, arranged between the shift yokes 81b, 82b, 83b and the countershaft 4 in the up-down direction, and arranged directly below the shift yokes 81b, 82b and 83b (see 7 and 11 ).

After coupling the right housing 21 and the left housing 22, the switching device 7 is fixed to the left housing 22. The switching device 7 is unified beforehand, and a part of the switching device 7 which projects further downward than the cover portion 71a is inserted into the left housing 22 through an opening 26 formed on the upper wall portion 24a. The inserted portion of the switching device 7 includes a part of the switching and selecting shaft 70, the suspension portion 71c of the switching housing 71, the cam member 74, the piston 75, the locking plate 77, and the switching guide 78. The lower end portion of the switching and selecting shaft 70 is inserted into the hole of the shaft support portion 29 in the left housing 22 and slidably supported by the shaft support portion 29 (see 7 ).

When the lid portion 71a of the switch case 71 is overlapped with the upper surface of the upper wall portion 24a and fixed by bolts or the like, the switch device 7 is completed. In this state, the finger portion 74a of the cam member 74 is located in one of the recesses of the first switch yoke 81b, the second switch yoke 82b, and the third switch yoke 83b and can transmit an operating force of the switch device 7 to the internal switch mechanism 8. In a state where fixing of the switch device 7 is completed, the front oil passage portion 93b is located directly below the finger portion 74a and the lock plate 77 and overlaps with the finger portion 74a in a plan view. The rear oil passage portion 92a, which is located rearward of the penetrating portion 96, is arranged to be located above the shaft support portion 29 and to extend between the cam member 74 and the rear wall portion 24c.

As described above, the penetration portion 96 of the oil groove 9 is located under the opening 26 of the left housing 22. A part of the switching device 7 inserted into the left housing 22 from the opening 26 is located inside the penetration portion 96. The oil groove 9 thus forms a branched oil passage surrounding the inserted portion of the switching device 7 inserted into the left housing 22, with the first oil passage 92 (the rear oil passage portion 92a) extending behind the inserted portion of the switching device 7, and the second oil passage 93 (the front oil passage portion 93b) extending in front of the inserted portion of the switching device 7 (see 7 ).

An operation of the oil trough 9 composed in the transmission case 20 as described above will be described. When the engine 1 is driven, rotation of the input shaft 3 is transmitted via the countershaft 4 and the final driven gear 60 rotates in the forward direction FW and the lubricating oil fed upward by the final driven gear 60 from the oil reservoir at the lower portion of the transmission case 20 flows into the collecting portion 90 of the oil trough 9. The lubricating oil entering the collecting portion 90 further flows to the inflow portion 91 while being guided by the flow regulating rib 91i or the like. The right side wall portion 91e and the front side wall portion 91f located in front of the collecting portion 90 are arranged so that their upper ends are located close to the upper wall portion 24a so as to be substantially close to a space from the final driven gear 60 to the upper wall portion 24a (see 8th ). Therefore, the lubricating oil flowing along the upper wall portion 24a and forcefully distributed forward can be reliably received into the inflow portion 91 beyond the collecting portion 90.

When a predetermined amount of the lubricating oil is received in the inflow portion 91, the lubricating oil is divided into the first oil passage 92 and the second oil passage 93 and flows downstream. A flow from the inflow portion 91 to the first oil passage 92 occurs when a liquid surface position in the inflow portion 91 reaches the bottom wall portion 92c of the first oil passage 92. A flow from the inflow portion 91 to the second oil passage 93 occurs when the liquid surface position in the inflow portion 91 reaches the lower end portion of the notch 91j. By appropriately adjusting the height positions of the bottom wall portion 92c and the lower end portion of the notch 91j, a timing at which the lubricating oil flows from the inflow portion 91 to the first oil passage 92 and a timing at which the lubricating oil flows from the inflow portion 91 to the second oil passage 93 can be adjusted.

The lubricating oil flowing into the first oil passage 92 flows from the rear oil passage portion 92a through the left oil passage portion 92b to a space behind and to the left of the shift and select shaft 70. When the lubricating oil has reached the rectifying rib 92f, the lubricating oil is temporarily stopped and flows around the rectifying rib 92f to the merging portion 94. Then, the lubricating oil enters the merging portion 94 from the gap between the rectifying rib 92f and the outer peripheral side wall portion 92e, and a forward flow becomes predominant due to guidance of the rectifying rib 94f.

On the other hand, the lubricating oil flowing into the second oil passage 93 accumulates in the oil collecting tank portion 93a adjacent to the inflow portion 91. When the lubricating oil in the oil collecting tank portion 93a exceeds a predetermined amount, the lubricating oil flows into the front oil passage portion 93b under the curved bottom wall portion 93d and the transition bottom wall portion 93f.

The lubricating oil flowing into the front oil passage portion 93b flows to a space in front of the shift and select shaft 70. When the lubricating oil has reached the rectifying rib 93j, the lubricating oil is temporarily stopped and passes through the gap between the rectifying rib 93j and the outer peripheral side wall portion 93h or flows out of the rectifying rib 93j to the merging portion 94. The lubricating oil entering the merging portion 94 via the second oil passage 93 is guided forward by the rectifying rib 94f.

The lubricating oil passing through the first oil passage 92 and the lubricating oil passing through the second oil passage 93 are guided along the rectifying rib 94f and merged in the merging portion 94 and reach the supply end portion 95. The lubricating oil reaching the supply end portion 95 is discharged from the end portion opening 95f to an outside of the oil groove 9. The end portion opening 95f is opened in the communication recess 116 of the left housing 22, and the lubricating oil discharged from the end portion opening 95f enters the communication recess 116 and enters the axial hole 3c of the input shaft 3 via the connecting recess 116 and the support recess 111 (see 9 ). Then, the amount of lubricating oil passing through the bearing 3b is controlled by the lubricating oil introducing element 117 (see 9 ) is set in the support recess 111 and the lubricating oil is supplied into the axial hole 3c. The lubricating oil passes through the axial hole 3c and the radial holes of the input shaft 3 and is supplied to the supporting portions of the transmission gears (30, 31, 32, 33, 34, 35) and the shift sleeves (36, 37) supported by the input shaft 3 to lubricate these portions.

Thereby, the oil groove 9 serves as a groove for guiding lubricating oil, which is carried up by the final driven gear 60, to a shaft end of the input shaft 3 located on the side of the left end wall 25 of the left housing 22 opposite to the partition wall 23. The oil groove 9 has the first oil passage 92 and the second oil passage 93 which are branched and extend respectively in front of and behind the switching device 7 and thus can be arranged in a limited space around the switching device 7 without interfering with the switching device 7 while ensuring a reliable flow rate of the lubricating oil.

Further, the lubricating oil supplied from the drip holes provided on the bottom wall of the oil groove 9 can be supplied to the transmission gears (40, 41, 42, 43, 44) and the shift sleeve (46) on the countershaft 4. The oil groove 9 includes the drip hole 100 on the bottom wall of the inflow portion 91, includes the drip holes 101 and 102 on the bottom wall of the second oil passage 93, and includes the drip holes 103 and 104 at positions adjacent to the second oil passage 93 of the merging portion 94. Through these drip holes, the lubricating oil can be directly supplied to the gear tooth surfaces of the transmission gears on the countershaft 4, which includes the first countershaft gear 40 to the fifth countershaft gear 44.

In particular, on the countershaft 4, as the gears move to a higher gear stage, the diameter of the transmission gears is reduced and the position of the drip hole must be located further forward. Therefore, by providing the second oil passage 93 extending at the front of the shift device 7, the lubricating oil can be reliably supplied directly above the gears of the gear stages that are not located below the first oil passage 92 extending behind the shift device 7. Consequently, excellent lubricating performance can be provided for all the gears on the countershaft 4.

As in 16 , in the oil groove 9, positions in the up-down direction of the bottom walls on which the drip holes are formed are different. Specifically, the lower bottom wall portion 93c on which the drip hole 105 is formed is located at a lowest position. The flat bottom wall portion 91b on which the drip hole 100 that drips the lubricating oil to the first counter gear 40 for the first speed is formed is located at the second lowest position. The curved bottom wall portion 93d on which the drip hole 101 that drips the lubricating oil to the second counter gear 41 for the second speed is formed is located at the third lowest position. The transition bottom wall portion 93f on which the drip hole 102 that drips the lubricating oil to the third counter gear 42 for the third speed is formed is located at the fourth lowest position. The upper bottom wall portion 94a, on which the drip holes 103, 104 are formed, through which the lubricating oil drips to the fourth counter gear 43 for the fourth speed and the fifth counter gear 44 for the fifth speed, is formed at the uppermost position. Thus, a bottom wall having a drip hole for a lower gear stage is formed at a lower position.

Therefore, when the engine 1 is driven to start traveling from a state in which no lubricating oil is stored in the oil groove 9, the lubricating oil flows from the collecting portion 90 into the inflow portion 91, and the lubricating oil starts dripping from the drip hole 100 located most upstream and lowest. When a remaining oil surface in the oil groove 9 rises and the lubricating oil flows from the inflow portion 91 to the second oil passage 93, the lubricating oil drips from the drip hole 101 located second upstream and second lowest. Then, when the lubricating oil is filled in the oil collecting tank portion 93a in which the drip hole 101 is provided, the lubricating oil drips from the drip hole 102 located third upstream and third lowest. Further, when the lubricating oil is filled in the merging portion 94 continuous with the second oil passage 93, the lubricating oil sequentially drips from the drip holes 100 and 104 located downstream of the drip hole 102 and above the drip hole 102. When the lubricating oil flows into the oil collecting tank portion 93a of the second oil passage 93, a predetermined amount of lubricating oil drips downward from the drain hole 105 located below all of the drip holes 100, 101, 102, 103 and 104.

As described above, the oil groove 9 is configured to drip the lubricating oil from a low-speed gear from the transmission gears on the countershaft 4 and to sequentially drip the lubricating oil to the high-speed gears as a vehicle speed increases, a rotational speed of the final output gear 60 increases, and a flow rate of the lubricating oil remaining in the oil groove 9 increases. For this reason, a low-speed gear is preferentially lubricated during low-speed driving, and in accordance with a transition from the low-speed driving to high-speed driving, the lubricating oil can be efficiently supplied to the shift gear stages in use.

The drip hole 101 and the drip hole 102 are respectively formed on the arcuately bent bottom wall portion 93d and the transition bottom wall portion 93f along the outer peripheral shapes of the second counter gear 41 and the third counter gear 42, and the drip holes 101 and 102 are respectively near the gears 41 and 42. Therefore, the lubricating oil dripping from the drip holes 101 and 102 can reliably reach the second counter gear 41 and the third counter gear 42.

The lubricating oil rotating together with the second counter gear 41 and the third counter gear 42 can be scraped off by the outer peripheral side wall portion 93h (including the inclined portion 93i) which continuously rises upward with the front sides of the bent bottom wall portion 93d and the transition bottom wall portion 93f. Thereby, an amount of the lubricating oil rotating together with the second counter gear 41 and the third counter gear 42 can be limited, thereby reducing the rotational resistance due to the viscosity of the lubricating oil.

The drip hole 103 and the drip hole 104 are respectively formed on the arc-shaped upper bottom wall portion 94a along the outer peripheral shapes of the fourth counter gear 43 and the fifth counter gear 44, and the drip holes 103 and 104 are respectively located near the gears 43 and 44. Thus, the lubricating oil dripped from the drip holes 103 and 104 can reliably and efficiently reach the fourth counter gear 43 and the fifth counter gear 44.

The lubricating oil rotating together with the fourth counter gear 43 and the fifth counter gear 44 can be scraped off by the front side wall portion 94d continuously rising upward with a front side of the upper bottom wall portion 94a. This can limit an amount of the lubricating oil rotating together with the fourth counter gear 43 and the fifth counter gear 44, thereby reducing the rotational resistance due to the viscosity of the lubricating oil.

Although the drip hole 100 is formed on the flat bottom wall portion 91b in the present embodiment, the drip hole 100 may be formed on the curved bottom wall portion 91c in front of the flat bottom wall portion 91b. Since the curved bottom wall portion 91c has an arc shape along the outer peripheral shape of the first counter gear 40 and the drip hole 100 is provided on the curved bottom wall portion 91c, the lubricating oil can drip from a position closer to the first counter gear 40.

The lubricating oil rotating together with the first counter gear 40 and the first shift sleeve 46 (including the reverse counter gear 47) can be scraped off by the front side wall portion 91f continuously rising upward with a front side of the bent bottom wall portion 91c. Thereby, an amount of the lubricating oil rotating together with the first counter gear 40 and the first shift sleeve 46 can be limited, thereby reducing the rotational resistance due to the viscosity of the lubricating oil.

In the transmission case 20, the lubricating oil is not only distributed to the gear mechanism 10 by the action of the oil groove 9, but also scattered to various locations to lubricate the internal switching mechanism 8 and the like. In the internal switching mechanism 8, the switching yokes 81b, 82b, and 83b have plate shapes extending in the horizontal direction and thus can easily receive the lubricating oil scattered from the transmission gear mechanism 10. As a result, the lubricating oil easily accumulates on the switching yokes 81b, 82b, and 83b and easily drips therefrom.

The front oil passage portion 93b of the oil groove 9 passes under the switching yokes 81b, 82b and 83b which are stacked in the up-down direction (see 7 and 10 ). Therefore, the lubricating oil falling down from the shift yokes 81b, 82b and 83b is caught by the oil groove 9 and prevented from reaching the side of the countershaft 4 below the oil groove 9. As described above, the control is performed so that an appropriate amount of lubricating oil is supplied to each transmission gear on the countershaft 4 by dripping from the oil groove 9, and when the lubricating oil falling down from the Shift yokes 81b, 82b and 83b adhere to each transmission gear, additional viscosity resistance can be applied. The oil groove 9 is arranged at a location between the internal shift mechanism 8 and the gear mechanism 10 in the up-down direction, thereby preventing excessive adhesion of the lubricating oil to the gear mechanism 10.

Since the oil groove 9 forms an oil passage surrounding the front, rear, left and right sides of the shift device 7, the lubricating oil scattered from the oil groove 9 to the inside of the penetration portion 96 can be used to lubricate the shift device 7 inserted into the penetration portion 96. In particular, by reducing the sliding resistance of the shift and select shaft 70 directly received by the shaft support portion 29 in the left housing 22 and improving the lubricity during the operation of the cam member 74, the performance of the shift and select operation can be improved. As shown in 7 As shown, an upper end position of the inner peripheral side wall portion 93g of the second oil passage 93 is located at substantially the same height position as an upper surface of the shaft support portion 29, an upper end position of the inner peripheral side wall portion 92d of the first oil passage 92 is located at substantially the same height position as the upper surface 77a of the lock plate 77, and the lubricating oil exceeding the inner peripheral side wall portion 93g and 92d is supplied to the shaft support portion 29 and the cam member 74.

The oil groove 9 having the branched oil passages surrounding the switching device 7 has excellent rigidity compared with an elongated oil groove extending in the left-right direction without being branched. In particular, the partition wall portion 91g separating the inflow portion 91 and the second oil passage 93 is high in the up-down direction and contributes greatly to improving the cross-sectional strength of an oil passage branch portion of the oil groove 9. Furthermore, the rectifying rib 91i allows the lubricating oil to flow smoothly from the collecting portion 90 to the inflow portion 91 and contributes to improving the strength of the vicinity of the boundary between the collecting portion 90 and the inflow portion 91. The rectifying rib 92f and the rectifying rib 93j control the flow of the lubricating oil from the first oil passage 92 and the second oil passage 93 to the merging section 94 and contribute to improving the strength of the vicinity of the downstream ends of the first oil passage 92 and the second oil passage 93. In addition, the oil groove 9 can also ensure the strength when the depth and shape of the bottom wall are partially changed.

In order to be arranged at the front of the switching and selecting shaft 70 in a narrow space in the up-down direction between the internal switching mechanism 8 and the transmission gear mechanism 10, the front oil passage portion 93b and the merging portion 94 of the oil groove 9 have a shape whose size in the up-down direction is small (whose side wall is low). On the other hand, at the front of the switching and selecting shaft 70, the shafts of the transmission gear mechanism 10 and the internal switching mechanism 8 are arranged in parallel in the front-back direction, and the switching yokes 81b, 82b and 83b extend in the front-back direction so as to form a space having a certain size in the front-back direction. Therefore, a passage cross-sectional area (a capacity) of the front oil passage portion 93b and the merging portion 94 is ensured by setting a length in the front-rear direction (a width) larger than a height (a depth) in the up-down direction (see 2 , 4 , 5 and 7 ).

The switching and selecting shaft 70 is arranged at the rear of the left housing 22. Therefore, the rear oil passage portion 92a of the oil groove 9 behind the switching and selecting shaft 70 has a shape whose size in the front-rear direction is small (whose distance between the inner peripheral side wall portion 92d and the outer peripheral side wall portion 92e is narrow) to be arranged in a narrow space in the front-rear direction between the switching and selecting shaft 70 and the rear wall portion 24c of the left housing 22 (see 7 ). On the other hand, at the rear of the shift and select shaft 70, since the space is not limited by the internal shift mechanism 8 and the transmission gear mechanism 10, the passage cross-sectional area (capacity) of the rear oil passage portion 92a is ensured by setting a height in the up-down direction (depth of the rear oil passage portion 92a) larger than a length in the front-back direction (width of the rear oil passage portion 92a). Specifically, the rear oil passage portion 92a is arranged in a space in the up-down direction obtained between the upper wall portion 24a and the shaft support portion 29. The outer peripheral side wall portion 92e of the first oil passage 92 rises in the up-down direction along the rear wall portion 24c, and its upper end is arranged close to the upper wall portion 24a.

As described above, in the oil groove 9, the branched first oil passage 92 and the second oil passage 93 are arranged with good space utilization without affecting the surrounding elements, thereby achieving both downsizing of the transmission 2 and high lubrication performance.

The oil groove 9 includes a portion serving as an intermediate storage portion that stores the lubricating oil in an area to the right of the shift and select shaft 70 and to the left of the final driven gear 60. This portion is located between the differential device 6 (the final driven gear 60) and the shift device 7 (shift and select shaft 70) and occupies a large area in the up-down direction and can easily secure a space in the up-down direction. Therefore, the oil groove 9 has a high degree of freedom of shape. In particular, the inflow portion 91 and the oil collecting tank portion 93a of the second oil passage 93 are provided as the intermediate storage portion having a depth that can store the lubricating oil.

The oil collecting tank portion 93a is located adjacent to the right side of the penetration portion 96 through which the switching and selecting shaft 70 is inserted. At this location in the left housing 22, since the shaft support portion 29 supporting the switching and selecting shaft 70 is absent at the right side of the shaft support portion 29 at the location in the left housing 22, the downward space limitation is smaller than a rear space of the switching and selecting shaft 70. Therefore, the lower bottom wall portion 93c of the oil collecting tank portion 93a can bulge further downward than the bottom wall portion 92c of the rear oil passage portion 92a, the upper wall portion 93e or the like (see 7 ). That is, the oil collecting tank portion 93a is disposed in an area to the right of the shaft support portion 29 and to the left of the first shift fork 81c, and the bottom wall of the oil collecting tank portion 93a (the lower bottom wall portion 93c) enters a space behind the second counter gear 41 and the third counter gear 42 and between the second counter gear 41, the third counter gear 42, and the rear wall portion 24c.

This is because, unlike the front oil passage portion 93b and the union portion 94, which are located directly above the countershaft 4, the lower bottom wall portion 93c of the oil collecting tank portion 93a is located behind the countershaft 4 and thus is not subjected to downward space limitation by the transmission gear mechanism 10. Therefore, the lower bottom wall portion 93c of the oil collecting tank portion 93a can bulge further downward than the upper bottom wall portion 93e of the front oil passage portion 93b and the upper bottom wall portion 94a of the union portion 94 (see 7 ).

The lower bottom wall portion 93c curves downward further than the flat bottom wall portion 91b of the inflow portion 91, which is located on the upstream side of the oil collecting tank portion 93a.

The flat bottom wall portion 91b is formed at the second lowest point between the bottom wall of the oil groove 9 next to the lower bottom wall portion 93c (see 16 ). In this way, the lower bottom wall portion 93c is formed deepest under the bottom wall of the oil groove 9, and the capacity of the oil collecting tank portion 93a is ensured by the depth of the lower bottom wall portion 93c.

However, the oil collecting tank portion 93a projects forward so as to be connected to the front oil passage portion 93b extending forward of the shift and select shaft 70. The forward projecting portion of the oil collecting tank portion 93a overlaps with the second counter gear 41 and the third counter gear 42 in the up-down direction and thus interferes with the second counter gear 41 and the third counter gear 42 when it remains at the height position of the lower bottom wall portion 93c. Therefore, the bottom wall in the forward projecting portion of the oil collecting tank portion 93a is formed by the curved bottom wall portion 93d which gradually becomes flatter toward the front, thereby avoiding interference with the second counter gear 41 and the third counter gear 42.

The transition bottom wall portion 93f that seamlessly connects the curved bottom wall portion 93d and the upper bottom wall portion 93e having different curvatures is provided at the boundary portion between the oil collecting tank portion 93a and the front oil passage portion 93b. Thereby, the lower bottom wall portion 93c and the upper bottom wall portion 93e, which are spaced apart from each other in the up-down direction with a step therebetween, are seamlessly connected by the curved bottom wall portion 93d and the transition bottom wall portion 93f, and the lubricating oil can be smoothly distributed from the oil collecting tank portion 93a to the front oil passage portion 93b.

The inflow section 91 is located to the right and behind the oil collecting tank section 93a. The inflow section 91 is in an area to the right of the shaft support portion 29 and to the left of the final driven gear 60, and the bottom wall of the inflow portion 91 (the flat bottom wall portion 91b and the curved bottom wall portion 91c) enters a space behind the first counter gear 40 and the first shift fork 81c and between the first counter gear 40, the first shift fork 81c and the rear wall portion 24c.

In this way, since the oil collecting tank portion 93a and the inflow portion 91, which are the intermediate storage portion whose bottom wall is lower than the bottom wall portion 90a (the first bottom wall portion) of the collecting portion 90 and the bottom wall portion 95a (the second bottom wall portion) of the supply end portion 95, are provided, the oil groove 9 has a function of not only flowing the lubricating oil but also storing the lubricating oil (an oil amount adjusting function during traveling or engine operation). Since the oil groove 9 holds a predetermined amount of the lubricating oil, the amount of the lubricating oil stored in the lower portion of the transmission case 20 is relatively reduced while the engine 1 is being driven or the vehicle is traveling and the lubricating oil is circulated. Therefore, even in a case where the amount of lubricating oil in the transmission case 20 is set larger in consideration of the initial lubrication from the engine stop state, in a state where the engine 1 is driven or traveling, the amount of lubricating oil (the height of the liquid surface) in which the gears in the transmission case 20 are immersed is reduced and the stirring resistance generated by stirring of the lubricating oil during gear rotation is reduced. The operating resistance of the transmission 2 can be reduced and the fuel consumption can be improved by efficient power transmission.

In addition to the intermediate storage portion such as the oil collecting tank portion 93a and the inflow portion 91, the oil groove 9 has an amount of retained lubricating oil increased due to the above-described branched structure of the oil passage and has a more advanced oil amount adjusting function.

Since the oil groove 9 itself has the function of storing the lubricating oil, it is not necessary to provide a large sump tank other than the oil groove 9. By eliminating the existing sump tank with the oil groove 9, a space-saving lubrication structure with few components can be achieved. Alternatively, even if a sump tank is used, a small one will suffice, thereby improving the degree of design freedom. In addition, the oil sump tank portion 93a and the inflow portion 91 are arranged by effectively utilizing a dead space in the vehicle transverse direction between the final driven gear 60 having a large diameter and the shift device 7 which is long in the up-down direction, thereby achieving excellent space utilization. By these elements, it is possible to reduce the size of the entire transmission.

In addition, the configuration in which the oil groove 9 has the function of storing the lubricating oil is also excellent in that this storing and supplying the lubricating oil to each part can be smoothly connected and the circulation state and the discharge amount of the lubricating oil can be easily and highly accurately controlled compared with a configuration in which an independent collecting tank is provided. Thus, since the oil collecting tank portion 93a and the inflow portion 91 are provided on the oil passage continuously with the end portion opening 95f which supplies lubricating oil to the shaft end of the input shaft 3 and the drip holes 100, 101, 102, 103 and 104 which drip the lubricating oil to the gears on the countershaft 4, an appropriate amount of lubricating oil can be supplied to these lubricating oil supply portions promptly.

In a state where the engine 1 is stopped and the circulation of the lubricating oil in the transmission case 20 is stopped, the lubricating oil falls downward from the drain hole 105 or the drip hole 100 on the bottom wall of the buffer portion (lower bottom wall portion 93c and flat bottom wall portion 91b), so that the oil groove 9 does not retain an excessive amount of the lubricating oil. In particular, since the drain hole 105 is formed on the lower bottom wall portion 93c located at the lowest point in the oil groove 9, the lubricating oil can be reliably drained from the oil catch tank portion 93a. Since the gears or the like constituting the transmission gear mechanism 10 are not arranged below the drain hole 105, the lubricating oil that has fallen from the drain hole 105 returns to the oil reservoir in the lower portion of the transmission case 20 without adhering to the transmission gears or the like. Thus, in the engine off state, a sufficient amount of the lubricating oil is reserved in the lower oil tank, and there is no fear of insufficient lubricating oil at an engine start.

The inflow section 91 adjacent to the oil collecting tank section 93a with the partition wall section 91g therebetween has the flat bottom wall portion 91b below the bottom wall portion 90a of the collecting portion 90 and the bottom wall portion 92c of the first oil passage 92. The depth of the flat bottom wall portion 91b ensures the capacity of the inflow portion 91. In the inflow portion 91, the lubricating oil can be stored in a height range from the flat bottom wall portion 91b to the lower end of the notch 91j. Thus, the inflow portion 91 adjacent to the upstream side of the oil collecting tank portion 93a also functions as an additional intermediate storage portion capable of storing a predetermined amount of the lubricating oil.

The inclined bottom wall portion 91d, which is seamlessly connected from the flat bottom wall portion 91b to the bottom wall portion 92c, is provided at the boundary portion between the inflow portion 91 and the first oil passage 92. The inclined bottom wall portion 91d allows the lubricating oil stored in the inflow portion 91 to smoothly flow to the first oil passage 92.

Although the inflow portion 91 has a smaller forward projection than the oil collecting tank portion 93a, a part of the front side of the inflow portion 91 overlaps with the first counter gear 40 and the first shift sleeve 46 in the up-down direction and thus interferes with the first counter gear 40 and the first shift sleeve 46 when it remains at the height position of the flat bottom wall portion 91b. Therefore, the bottom wall at the front edge portion of the inflow portion 91 is formed by the curved bottom wall portion 91c which gradually becomes flatter toward the front side, thereby avoiding interference with the first counter gear 40 and the first shift sleeve 46.

When the lubricating oil accumulates in the lower end position of the notch 91j in the inflow portion 91, the lubricating oil flows down through the notch 91j into the oil collecting tank portion 93a. Since the step in the up-down direction from the lower end of the notch 91j to the lower bottom wall portion 93c is large (see 16 ), the lubricating oil can forcefully flow from the inflow portion 91 to the second oil passage 93. The flow rate and force of the lubricating oil from the inflow portion 91 to the second oil passage 93 can be adjusted accordingly by changing the shape and position of the notch 91j. Thus, the amount of the lubricating oil flowing through the notch 91j can be limited by the width dimension of the notch 91j, and the lubricating oil can be stored in the inflow portion 91 at a position higher than the lower end position of the notch 91j due to the relationship between the inlet amount to the collecting portion 90 and the outlet amount to the first oil passage 92.

In addition, the second oil passage 93, as described above, extends when the oil groove 9 is viewed from above (see 12 ) at an extension of the opening of the notch 91j (to the oblique left front side as viewed from the inflow portion 91 side). This allows the lubricating oil to smoothly flow from the notch 91j to the second oil passage 93. Moreover, the bottom wall of the second oil passage 93 connects the deeper lower bottom wall portion 93c and the shallower upper bottom wall portion 93e with the curved bottom wall portion 93d and the transition bottom wall portion 93f having smooth shapes, and this bottom wall shape also contributes to the smooth flow of the lubricating oil.

As described above, the lubricating structure of the transmission according to the present embodiment includes the oil groove 9 whose capacity of lubricating oil is increased by installing the intermediate storage portion and the branched structure of the oil passage. Thereby, it is possible to adjust the lubricating oil in the lower part of the transmission case 20 in an engine driving state to an appropriate amount, reduce the stirring resistance of the lubricating oil with respect to the rotation of the gears, and improve driving efficiency and fuel consumption. Since the oil groove 9 itself stores the lubricating oil, it is possible to reduce the cost and labor of separately providing a large sump, as well as reduce the size of the transmission and improve the space utilization in the transmission case 20.

In the lubricating structure of the transmission according to the present embodiment, the oil groove 9 includes the penetrating portion 96 penetrating in the up-down direction, and a part of the switching device 7 is located in the penetrating portion 96. This configuration is capable of improving the lubricating performance (flow rate and degree of freedom of the lubricating oil supply position) in the oil groove 9 without affecting the switching device 7. Furthermore, due to the oil passage structure branched with the penetrating portion 96 interposed therebetween, it is possible to obtain the effect of improving the rigidity of the oil groove 9 and the like.

The present invention is not limited to the above embodiment, and various changes may be made thereto The sizes, shapes and the like shown in the drawings are not limited to the above embodiment and can be modified appropriately within a range in which the effect of the present invention can be achieved. Various changes can be made thereto without departing from the scope of the subject matter of the present invention.

For example, in the above embodiment, the lubricating oil flows into the second oil passage 93 through the notch 91j formed on the partition wall portion 91g which is the side wall of the inflow portion 91g while the height position of the first oil passage 92 and the inflow portion 91 is different from the height position of the second oil passage 93. In contrast to this configuration, it is also possible to use an oil groove in a form in which the two oil passages are branched by the partition wall while the heights of the two oil passages at the branch portion are the same.

Although the notch 91j of the above embodiment has a rectangular shape whose upper end is open, it is also possible to guide the lubricating oil to the branch oil passage with a notch having a shape other than a rectangle or a through hole having a closed shape whose peripheral edge is not opened.

Although the oil storage tank portion 93a is provided at the upstream portion of the second oil passage 93 passing through the front of the switching device 7 in the above embodiment, it is also possible to provide the buffer portion at another position in the second oil passage 93 or at the first oil passage 92.

A number of buffer portions provided on the oil groove may be either a single one or a plurality, and the capacity, positional relationship, and the like of each other when a plurality of buffer portions are provided can be arbitrarily set. For example, in the oil groove 9 of the above embodiment, the buffer portion that satisfies the requirement that its bottom wall is located lower than the bottom wall portion 90a of the collecting portion 90 and the bottom wall portion 95a of the supply end portion 95 is the oil collecting tank portion 93a (the lower bottom wall portion 93c) and the inflow portion 91 (the flat bottom wall portion 91b). In contrast to this configuration, it is also possible to raise the lower wall position of the inflow portion 91 and use only the oil collecting tank portion 93a as the buffer portion. Alternatively, a buffer may be separately provided on the first oil passage 92.

The configuration of the transmission gear mechanism and the like in the transmission is not limited to the above embodiment. For example, the transmission gear mechanism 10 of the above embodiment includes the input shaft 3, the countershaft 4, and the reverse shaft 5 as transmission shafts, but may be applied to a transmission of a type having a different number of transmission shafts or different functions of the transmission shafts. The oil groove 9 of the embodiment supplies the lubricating oil to the axial hole 3c at the shaft end of the input shaft 3 and drops the lubricating oil onto the transmission gears on the countershaft 4, but depending on the configuration of the transmission, the oil groove may also be configured to supply the lubricating oil to the axial hole 4c at the shaft end of the countershaft 4 and drip the lubricating oil onto the gears on the input shaft 3.

As described above, the present invention is effective to optimize a flow state of lubricating oil in a transmission and improve lubrication performance to a lubrication target portion with a simple and space-saving configuration, and is particularly useful in a transmission requiring a smaller size and low cost.

List of reference symbols

1

Drive machine

2

transmission

3

Input shaft (gearbox shaft)

4

Countershaft (gearbox shaft)

5

Reverse shaft (gearbox shaft)

6

Differential device

7

Switching device

8th

internal switching mechanism

9

Oil channel

10

Gear mechanism

20

Gearbox housing

30

first input gear (gearbox gears)

31

second input gear (gearbox gears)

32

third input gear (gearbox gears)

33

fourth input gear (gearbox gears)

34

fifth input gear (gearbox gears)

35

Reverse input gear (transmission gears)

36

second shift sleeve

37

third shift sleeve

40

first countershaft gear (gearbox gears)

41

second countershaft gear (gearbox gears)

42

third countershaft gear (gearbox gears)

43

fourth countershaft gear (gearbox gears)

44

fifth countershaft gear (gearbox gears)

45

Final drive gear

46

first shift sleeve

47

Reverse countershaft gear (transmission gears)

50

Reverse idle gear (transmission gears)

60

Final drive gear

70

Shift and selection shaft

81

first switching unit

81a

first shift shaft

81b

first switching yoke

81c

first shift fork

82

second switching unit

82a

second shift shaft

82b

second switching yoke

82c

second shift fork

83

third switching unit

83a

third shift shaft

83b

third switching yoke

83c

third shift fork

90

Collection section

90a

Floor wall section (first floor wall section)

91

Inflow section (intermediate storage section)

91y

score

92

first oil passage

93

second oil passage

93a

Oil collection tank section (intermediate storage section)

93b

front oil passage section

93c

lower floor wall (third floor wall section)

93d

curved floor wall section (arch section)

93f

Transitional floor wall section (arch section)

93i

inclined section (inclined surface)

94

Unification section

95

Feed end section

95a

Floor wall section (second floor wall section)

96

Penetration section

100

Drip hole

101

Drip hole

102

Drip hole

103

Drip hole

104

Drip hole

105

Drain hole

Claims (14)

An oil groove (9) for a transmission (2) in which an oil passage (92, 93) surrounded by a bottom wall (92c, 93c, 93d, 93e, 93f) and side walls (92d, 92e, 93g, 93h) protruding upward from the bottom wall (92c, 93c, 93d, 93e, 93f) is formed, the oil groove (9) for the transmission (2) comprising: a collecting section (90) into which lubricating oil conveyed up from a lower section of the transmission (2) is to flow, and a supply end section (95) designed to convey lubricating oil to a shaft end of a transmission shaft (3) carrying a transmission gear (30-35), an intermediate storage section (93a) designed to store the lubricating oil and on which the bottom wall (93c) is located lower than a first bottom wall portion (90a) which is the bottom wall at the collecting portion (90), and a second bottom wall portion (95a) which is the bottom wall at the supply end portion (95) is provided between the collecting portion (90) and the supply end portion (95); wherein at least a part (93) of the oil passage (92, 93) is located above a transmission gear (41) and wherein a part of the bottom wall (93c, 93d) located above the transmission gear (41) is provided with a drip hole (101) configured to allow lubricating oil to drip from the oil passage (93) to the transmission gear (41), characterized in that the part of the bottom wall (93c, 93d) located above the transmission gear (41) has an arc portion (93d) having an arc shape along an outer periphery of the transmission gear (41), and the drip hole (101) is formed on the arc portion (93d). The oil groove (9) for a gearbox (2) according to Claim 1 wherein a third bottom wall portion (93c) which is the bottom wall at the intermediate storage portion (93a) is bulged downward with respect to the bottom wall (91b, 93e) adjacent to an upstream side and a downstream side of the intermediate storage portion (93a). The oil groove (9) for a gearbox (2) according to Claim 1 or 2 , comprising: a plurality of intermediate storage sections (91, 93a) having different up-down directional positions of the bottom wall (91b, 93c). The oil groove (9) for a transmission (2) according to one of the Claims 1 until 3 , wherein the transmission (2) comprises: a shift yoke (81b, 82b, 83b) supported by a shift shaft (81a, 82a, 83a) located above the transmission shaft (3), and a shift fork (81c, 82c, 83c) supported by the shift yoke (81b, 82b, 83b) and configured to switch an engagement relationship of a plurality of transmission gears (30-35, 40-44, 47, 50) by an axial movement of the shift shaft (81a, 82a, 83a), and wherein the oil passage (93) extends under the shift yoke (81b, 82b, 83b) and above the transmission gear (41, 42). The oil groove (9) for a gearbox (2) according to Claim 4 wherein the side walls have an inclined surface (93i) which is inclined with respect to an axial direction of the shift shaft (81a, 82a) and can come into contact with an outer end of the shift shaft (81a, 82a) when the transmission (2) is assembled. The oil groove (9) for a gearbox (2) according to Claim 1 , comprising: a plurality of drip holes (100-104) each configured to drip lubricating oil to a plurality of transmission gears (30-35, 40-44, 47, 50), wherein the bottom wall provided with the drip holes (100-104) is arranged the lower the lower the gear stage of the transmission gear (30-35, 40-44, 47, 50) to which the lubricating oil drips. An oil groove (9) for a transmission (2) in which an oil passage (92, 93) surrounded by a bottom wall (92c, 93c, 93d, 93e, 93f) and side walls (92d, 92e, 93g, 93h) protruding upward from the bottom wall (92c, 93c, 93d, 93e, 93f) is formed, the oil groove (9) for the transmission (2) comprising: a collecting section (90) into which lubricating oil conveyed up from a lower section of the transmission (2) is to flow, and a supply end section (95) designed to convey lubricating oil to a shaft end of a transmission shaft (3) carrying a transmission gear (30, 31, 32, 33, 34, 35), characterized in that the Oil groove (9) has a penetrating portion (96) penetrating in the up-down direction, and a part of a switching device (7) transmitting a switching operation of the transmission (2) is located in the penetrating portion (96). The oil groove (9) for a gearbox (2) according to Claim 7 wherein the oil passage (92, 93) from the collecting portion (90) to the supply end portion (95) has a first oil passage (92) and a second oil passage (93) which are branched with the penetrating portion (96) interposed therebetween, and wherein lubricating oil flows between the first oil passage (92) and the second oil passage (93) through a notch (91j) formed on the side walls. The oil groove (9) for a gearbox (2) according to Claim 8 wherein the first oil passage (92) and the second oil passage (93) have different positions of the bottom wall (92c, 93c) in the up-down direction, and lubricating oil flows through the notch (91j) from a side located above to a side located below between the first oil passage (92) and the second oil passage (93). The oil groove (9) for a transmission (2) according to one of the Claims 7 until 9 , wherein the transmission (2) comprises: a shift yoke (81b, 82b, 83b) supported by a shift shaft (81a, 82a, 83a) located above the transmission shaft (3), and a shift fork (81c, 82c, 83c) supported by the shift yoke (81b, 82b, 83b) and configured to switch an engagement relationship of a plurality of transmission gears (30-35, 40-44, 47, 50) by an axial movement of the shift shaft (81a, 82a, 83a), and wherein the oil passage (93) is located under the shift yoke (81b, 82b, 83b) and over a gear wheel (41, 42). The oil groove (9) for a gearbox (2) according to Claim 10 wherein the side walls have an inclined surface (93i) which is inclined with respect to an axial direction of the shift shaft (81a, 82a) and can come into contact with an outer end of the shift shaft (81a, 82a) when the transmission (2) is assembled. The oil groove (9) for a transmission (2) according to one of the Claims 7 until 11 , wherein at least a part (93) of the oil passage (92, 93) is located above a transmission gear (41), and wherein a part of the bottom wall (93c, 93d) located above the transmission gear (41) is provided with a drip hole (101) configured to allow lubricating oil to drip from the oil passage (93) to the transmission gear (41). The oil groove (9) for a gearbox (2) according to Claim 12 , comprising: a plurality of drip holes (100-104) each configured to drip lubricating oil to a plurality of transmission gears (30-35, 40-44, 47, 50), wherein the bottom wall provided with the drip holes (100-104) is arranged the lower the lower the gear stage of the transmission gear (30-35, 40-44, 47, 50) to which the lubricating oil drips. The oil groove (9) for a gearbox (2) according to Claim 12 or 13 wherein the part of the bottom wall (93c, 93d) located above the transmission gear (41) has an arc portion (93d) having an arc shape along an outer periphery of the transmission gear (41), and the drip hole (101) is formed at the arc portion (93d).

Images