JP2008044541A - Power unit for vehicle - Google Patents

Abstract

An input shaft for transmitting power from a crankshaft to a transmission case, an output shaft parallel to the input shaft, and a plurality of shifts provided between the input shaft and the output shaft to enable selective establishment. In a vehicle power unit in which a gear transmission mechanism including a gear train of stages is accommodated and a bevel gear mechanism is provided between a drive shaft and an output shaft that extend in a direction perpendicular to the axis of the output shaft and transmit power to the rear wheels, Assembling performance of the gear transmission mechanism and the bevel gear mechanism is improved.
A gear speed change mechanism and a bevel gear mechanism are connected so as to be capable of being assembled to a transmission case in a state where the bevel gear mechanism is connected to an output shaft.
[Selection] Figure 3

Description

  According to the present invention, a crankshaft having an axis line in the vehicle width direction is rotatably supported by a crankcase of an engine body mounted on a vehicle body frame, and is connected to a rear portion of the crankcase along a vehicle traveling direction. An input shaft for transmitting power from the crankshaft to the transmission case, an output shaft parallel to the input shaft, and a plurality of shift stages provided between the input shaft and the output shaft to enable selective establishment. The present invention relates to a vehicle power unit in which a gear transmission mechanism including a gear train is accommodated, a drive shaft that extends in a direction perpendicular to the axis of the output shaft and transmits power to a rear wheel, and a bevel gear mechanism is provided between the output shafts.

For example, Patent Document 1 discloses a power unit in which an output from a transmission in a power unit of a motorcycle is transmitted via a bevel gear mechanism to a drive shaft extending in the front-rear direction so as to transmit power to a rear wheel.
JP-A-4-271986

  However, in the power unit disclosed in Patent Document 1, the output shaft of the gear transmission mechanism passes through the transmission case in a rotatable manner, and covers the protruding portion of the output shaft from the transmission case. A bevel gear mechanism connected to the output shaft is accommodated in a gear case to be attached so as to be supported by the gear case. Therefore, the clearance adjustment between the driving bevel gear and the driven bevel gear in the bevel gear mechanism must be performed after the bevel gear mechanism is connected to the output shaft and before the gear case is assembled to the transmission case. The assembling work is complicated.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle power unit in which the assembly of the gear transmission mechanism and the bevel gear mechanism is improved.

  In order to achieve the above object, according to the first aspect of the present invention, a crankshaft having an axis line in the vehicle width direction is rotatably supported on a crankcase of an engine body mounted on a vehicle body frame, and the vehicle traveling direction is An input shaft to which power is transmitted from the crankshaft, an output shaft parallel to the input shaft, and a transmission case connected to a rear portion of the crankcase along the input shaft can be selectively established. And a gear transmission mechanism including a gear train having a plurality of speed stages provided between the output shafts, and extending between a direction orthogonal to the axis of the output shaft and transmitting power to a rear wheel between the drive shaft and the output shaft In the vehicle power unit in which the bevel gear mechanism is provided, the gear transmission mechanism and the bevel gear mechanism can be assembled to the transmission case in a state where the bevel gear mechanism is connected to the output shaft. Characterized in that it is binding.

  According to a second aspect of the invention, in addition to the configuration of the first aspect of the invention, the transmission case is provided with an opening through which the gear transmission mechanism in an assembled state can be inserted into the transmission case. The bevel gear mechanism side ends of the input shaft and the output shaft are rotatably supported by a holder attached to the transmission case so as to close the opening, and a part of the bevel gear mechanism A gear case that supports a driven bevel gear that is non-rotatably coupled to the drive shaft and accommodates the bevel gear mechanism is attached to the holder, and constitutes a part of the gear train of a plurality of shift stages Then, the driven bevel gear is arranged at a position where a part of the driven bevel gear is superimposed on a plane orthogonal to the axis of the crankshaft on the drive gear of the smallest diameter among the drive gears mounted on the input shaft. Is arranged.

  In addition to the configuration of the invention described in claim 1 or 2, the invention described in claim 3 is configured such that the crankcase in which the transmission case is integrally connected is divided into two vertically, and the crankcase An axis of the output shaft is arranged on the dividing surface, and an axis of the input shaft is arranged at a position shifted downward from the dividing surface between the axis of the crankshaft and the axis of the output shaft. .

  Since the gear transmission mechanism can be assembled to the transmission case in a state of being connected to the bevel gear mechanism, the gear transmission mechanism is assembled to the transmission case together with the bevel gear mechanism after adjusting the clearance in the bevel gear mechanism. It is possible to improve assembly.

  According to the second aspect of the present invention, the gear speed change mechanism is assembled by supporting the bevel gear mechanism side ends of the input shaft and the output shaft on the holder, and the gear case covering the bevel gear mechanism connected to the output shaft. After the clearance adjustment is completed with the holder attached to the holder, the holder is attached to the transmission case, so that the gear transmission mechanism connected to the bevel gear mechanism after the clearance adjustment is completed is assembled to the transmission case. Can do. In addition, the bevel gear mechanism can be arranged close to the crankshaft side to concentrate the mass in the engine body, and even if the driven bevel gear is arranged on the input shaft side in the gear transmission mechanism, the gear case It can be avoided that the portion of the holder that supports the driven bevel gear interferes with the portion of the holder that supports the end of the input shaft on the bevel gear mechanism side.

  Furthermore, according to the invention described in claim 3, the length of the engine body in the front-rear direction can be shortened, and the vertical distance between the input shaft and the dividing surface can be shortened to reduce the speed of the transmission in the width direction of the engine body. The lower part can be made compact.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

  1 to 6 show an embodiment of the present invention. FIG. 1 is a side view of a motorcycle, FIG. 2 is an enlarged side view of a main part of an engine body, and FIG. 3 is a gear transmission mechanism and a bevel gear mechanism. 2 is an enlarged cross-sectional view taken along line 3-3 in FIG. 2, and FIG. 4 is a cross-sectional view showing the structure between the crankshaft and the input shaft of the gear transmission mechanism cut along line 4-4 in FIG. 5 is a sectional view taken along line 5-5 in FIG. 3, and FIG. 6 is a sectional view taken along line 6-6 in FIG.

  First, in FIG. 1, a front fork 12 that pivotally supports a front wheel WF is supported on a head pipe 11 provided at a front end of a body frame F of a motorcycle so that the steering wheel 13 is connected to the front fork 12. . A power unit P including an engine E and a transmission M that changes the output of the engine E is mounted on the front portion of the vehicle body frame F. A fuel tank is provided so as to cover the upper side of the engine E. 15 is mounted on the front portion of the vehicle body frame F.

  The front ends of a pair of left and right swing arms 16 extending in the front-rear direction are supported on the body frame F behind the power unit P so as to swing up and down, and a rear wheel WR is pivoted between the rear ends of the swing arms 16. Be supported. Further, rear cushion units 17 are interposed between the body frame F and the rear portions of the swing arms 16. The left swing arm 16 of the two swing arms 16 is formed in a cylindrical shape, and the drive shaft 18 for transmitting the power from the power unit P to the rear wheel WR is accommodated in the left swing arm 16. .

  A ride seat 19 for a rider to sit on the vehicle body frame F is provided behind the fuel tank 15. A front fender 20 that covers the front wheel WF from above is attached to the front fork 12, and a rear fender 21 that covers the rear wheel WR from above is attached to the rear portion of the vehicle body frame F.

  Referring also to FIG. 2, the engine body 24 of the V-type four-cylinder water-cooled engine E includes a crankcase 14 that rotatably supports a crankshaft 25 having an axis line along the vehicle width direction, A pair of front and rear cylinder blocks 26F, 26R, which are arranged in a V-shape that is open toward the crankcase 14 and coupled to the crankcase 14, cylinder heads 27F, 27R respectively coupled to the cylinder blocks 26F, 26R, and cylinders thereof Head covers 28F and 28R coupled to the upper ends of the heads 27F and 27R, respectively.

  Thus, a front bank BF composed of a cylinder block 26F, a cylinder head 27F, and a head cover 28F disposed on the front side along the traveling direction of the motorcycle, and a cylinder disposed on the rear side along the traveling direction of the motorcycle. A rear bank BR including a block 26R, a cylinder head 27R, and a head cover 28R is connected to the crankcase 14 so as to form a V shape.

  Referring also to FIG. 3, a transmission case 29 is integrally connected to the rear portion of the crankcase 14 along the vehicle traveling direction, and power is transmitted from the crankshaft 25 to the transmission case 29. Input shaft 30, an output shaft 31 parallel to the input shaft 30, and a plurality of shift stages provided between the input shaft 30 and the output shaft 31 to enable selective establishment, for example, for first to sixth speeds A gear speed change mechanism 32 including a gear train G1 to G6 is accommodated, and the bevel gear mechanism extends between the output shaft 31 and the drive shaft 18 that extends in a direction orthogonal to the axis of the output shaft 31 and transmits power to the rear wheel WR. 33 is provided.

  The input shaft 30 and the output shaft 31 have an axis parallel to the crankshaft 25. The transmission case 29 has an inner wall portion 29a and an outer wall portion 29b that are spaced in the direction along the axis of the input shaft 30 and the output shaft 31, and one end portion of the input shaft 30 is an inner wall portion 29a. The one end of the output shaft 31 is rotatably supported by the inner wall 29a via a roller bearing 34 while being rotatably supported.

  In FIG. 4, the input shaft 30 has a ball bearing 35 interposed between the input wall 30 and the inner wall 29a so as to freely rotate. Rotational power from the crankshaft 25 is input to the projecting portion via the primary reduction mechanism 36, the damper spring 37, and the clutch 38.

  The primary speed reduction mechanism 36 includes a primary drive gear 39 attached to the crankshaft 25 and a primary driven gear 40 meshing with the primary drive gear 39. The primary drive gear 39 is configured as a so-called swirl gear. The driven gear 40 is rotatably supported by a sleeve 41 that surrounds the input shaft 30 and is attached to the input shaft 30 via a needle bearing 42.

  The clutch 38 includes a clutch outer 43 in which a damper spring 37 is interposed between the clutch and the primary driven gear 40; a clutch inner 44 fixed to a cylindrical boss 108 that is splined to the input shaft 30; A plurality of driving friction plates 45 engaged with the inner periphery of the clutch outer 43 and a plurality of covered members engaged with the inner periphery of the clutch inner 44 so as to be sandwiched between the driving friction plates 45. The moving friction plates 46 are opposed to one end of the driving friction plates 45 and the driven friction plates 46 which are superposed on each other, and are supported so as to be movable within a range limited in the direction along the axis of the input shaft 30. A release plate 47 and a receiver provided integrally with the clutch inner 44 so as to face the other ends of the drive friction plates 45 and the driven friction plates 46 from the opposite side of the release plate 47. It comprises a plate 48, a clutch spring 49 for biasing the release plate 47 on the side to be close to the pressure receiving plate 48.

  Further, the central portion of the release plate 47 is connected to a support member 51 through a ball bearing 50, and the rod 52 for connecting one end portion to the support member 51 is formed in a cylindrical shape. It is inserted coaxially and movably in the axial direction. Thus, the axial movement of the rod 52 switches the engagement / disengagement of the clutch 38. That is, by driving the release plate 47 with the rod 52 on the side separated from the pressure receiving plate 48 against the spring force of the clutch spring 49, power transmission between the crankshaft 25 and the input shaft 30 is cut off. The crankshaft 25 and the input shaft 30 are connected by displacing the rod 52 in the axial direction so that the release plate 47 is brought close to the pressure receiving plate 48 by the spring force of the clutch spring 49.

  Moreover, the primary driven gear 40, the damper spring 37, and the clutch 38 of the primary speed reduction mechanism 36 are assembled to the input shaft 30 through the ball bearing 35 through the inner wall portion 29a of the transmission case 29. The input shaft 30 before the primary driven gear 40, the damper spring 37, and the clutch 38 are assembled is inserted into the ball bearing 35 attached to the inner wall portion 29a of the transmission case 29, thereby allowing the input shaft 30 to pass through the ball bearing 35. And is supported by the inner wall portion 29a. Further, one end portion of the output shaft 31 is also inserted into a roller bellering 34 mounted on the inner wall portion 29 a, so that the output shaft 31 is supported by the inner wall portion 29 a via the roller bellering 34.

  In FIG. 3 again, the first-speed gear train G1 is supported by the first-speed drive gear 53 and the first-speed drive gear 53, which are integrally provided on the input shaft 30, and are rotatably supported by the output shaft 31. The second-speed gear train G2 includes a meshed first-speed driven gear 54 and a second-speed drive gear 55 that is coupled to the input shaft 30 so as not to rotate relative to the input shaft 30, and is rotatable relative to the output shaft 31. The third-speed gear train G3 is composed of a second-speed driven gear 56 that is supported and meshed with the second-law drive gear 55. The third-speed gear train G3 is supported on the input shaft 30 so as not to be relatively rotatable. 57 and a third-speed driven gear 58 that is rotatably supported on the output shaft 31 and meshes with the third-speed drive gear 57, and the fourth-speed gear train G 4 rotates relative to the input shaft 30. It is supported so that it can rotate relative to the output gear 31 and the fourth-speed drive gear 59 that is supported impossible. The fifth speed gear train G5 includes a fourth speed driven gear 60 that meshes with the fourth speed drive gear 59, and the fifth speed gear train G5 is rotatably supported on the input shaft 30. The sixth-speed gear train G6 is supported on the input shaft 30 so as to be relatively rotatable. The fifth-speed driven gear 62 is supported on the output shaft 31 so as not to rotate relative to the output shaft 31 and meshes with the fifth-speed drive gear 61. And a sixth speed driven gear 64 that is supported on the output shaft 31 so as not to rotate relative to the output shaft 31 and meshes with the sixth speed drive gear 63.

  Between the fifth speed drive gear 61 and the sixth speed drive gear 63, the input shaft 30 is engaged with the fifth speed drive gear 61 to establish the fifth speed gear train G5, the sixth speed A first position for selectively switching a position where the sixth gear train G6 is established by engaging with the driving gear 63 and a neutral position where the sixth gear train G6 is not engaged with any of the fifth and sixth speed driving gears 61, 63. The shifter 65 is spline-coupled, and the third and fifth speed drive gears 57 and 59 are provided integrally with the first shifter 65. Further, the output shaft 31 between the first speed driven gear 54 and the fourth speed driven gear 60 is engaged with the first speed driven gear 54 to establish the first speed gear train G1, A position where the fourth gear train G4 is established by being engaged with the speed driven gear 60 and a neutral position where the gear gear G4 is not engaged with any of the first and fourth speed driven gears 54, 60 are selectively switched. The second shifter 66 is spline-coupled, and the fifth speed driven gear 62 is provided integrally with the second shifter 66. Further, between the second speed driven gear 56 and the third speed driven gear 58, the output shaft 31 is engaged with the second speed driven gear 56 to establish the second speed gear train G2, A position where the third gear train G3 is established by engaging with the speed driven gear 58 and a neutral position where the second gear and the third speed driven gear 56, 58 are not engaged are selectively switched. The third shifter 67 is spline-coupled, and the sixth speed driven gear 64 is provided integrally with the third shifter 67.

  Referring also to FIG. 5, the bevel gear mechanism 33 includes a drive bevel gear 71 coupled to the output shaft 31 so as not to be relatively rotatable, and a driven bevel gear 72 meshed with the drive bevel gear 71. It is.

  By the way, the gear transmission mechanism 32 and the bevel gear mechanism 33 are connected so that they can be assembled to the transmission case 29 in a state where the bevel gear mechanism 33 is connected to the output shaft 31. For this reason, the outer wall portion 29b of the transmission case 29 is provided with an opening 68 having a size that allows the gear transmission mechanism 32 in an assembled state to be inserted into the transmission case 29. A holder 69 is attached to the outer wall portion 29b so as to close the opening 68. The holder 69 has end portions on the bevel gear mechanism 33 side of the input shaft 30 and the output shaft 31, that is, The other end is rotatably supported.

  An output shaft 31 is spline-coupled to a cylindrical portion 71 a that is provided integrally and coaxially with the drive bevel gear 71 of the bevel gear mechanism 33 and rotatably passes through the holder 69, and a ball bearing is provided between the cylindrical portion 71 a and the holder 69. 73 is interposed. Moreover, the holder 69 is integrally provided with a cylindrical fitting tube portion 69a that is coaxial with the cylindrical portion 71a and protrudes toward the gear case 70, and this fitting cylinder portion 69a is provided on the gear case 70. The fitting hole 81 is fitted through the seal member 82.

  The driven bevel gear 72 has a cylindrical portion 72 a coaxially and integrally, and the cylindrical portion 72 a is rotatably supported by the gear case 70 via a ball bearing 74. One end of a transmission shaft 75 having an axis orthogonal to the axis of the output shaft 31 and the drive bevel gear 71 is spline-coupled to the driven bevel gear 72. The transmission shaft 75 is connected to the rear portion of the gear case 70. The support hole 76 is provided coaxially through the support hole 76, extends rearward, and is connected to the drive shaft 18 so as not to be relatively rotatable.

  The support hole 76 is integrally provided with a cylindrical support cylinder portion 77a that fits in the support hole 76 in an airtight manner, and is closed by a lid member 77 that is fastened to the gear case 70 by a plurality of bolts 78. A ball bearing 79 and a seal member 80 on the outer side of the ball bearing 79 are interposed between the lid member 77 and the transmission shaft 75 that passes through the lid member 77 coaxially. .

  The gear case 70 is fastened to the holder 69 by a plurality of bolts 83... Of the bolts 83... Used to fasten to 29b.

  By the way, the clearance adjustment between the driving bevel gear 71 and the driven bevel gear 72 in the bevel gear mechanism 33 is performed by adjusting the thickness or number of shims 109 sandwiched between the outer wall portion 29b of the transmission case 29 and the gear case 70, and the gear case 70 and The clearance adjustment is performed by changing the thickness or the number of shims 110 sandwiched between the lid members 77. Such a clearance adjustment is a holder of the gear case 70 that houses the bevel gear mechanism 33 connected to the output shaft 31. It is executed at the time of attachment to 69.

  Thus, in a state where the gear case 70 and the holder 69 are fastened to the outer wall portion 29b of the transmission case 29, a part of the first to sixth gear trains G1 to G6 is configured as clearly shown in FIG. Thus, one of the first to sixth speed drive gears 53, 55, 57, 59, 61, 63 mounted on the input shaft 30 is added to the first speed drive gear 53 having the smallest diameter. The driven bevel gear 72 is arranged so that a part of the portion overlaps on a projection view onto a plane orthogonal to the axis of the crankshaft 25.

  The crankcase 14 of the engine body 24 is integrally provided with the transmission case 29. The crankcase 14 can be divided into two parts vertically as shown in FIG. The axis of the output shaft 31 is arranged, and the axis of the input shaft 30 is arranged at a position shifted downward from the dividing surface 85 between the axis of the crankshaft 25 and the axis of the output shaft 31.

  Referring also to FIG. 6, a shift drum 86 having an axis parallel to the output shaft 31 is disposed below the output shaft 31, and a shifter shaft 87 parallel to the shift drum 86 is connected to the shift drum 86 and the output. Arranged between the shafts 31. The shifter shaft 87 supports the first to third shift forks 111, 112, 113 holding the first to third shifters 65 to 67 of the gear transmission mechanism 32 so as to be slidable in the axial direction. 113 is engaged with a cam groove provided on the outer periphery of the shift drum 86.

  One end of the shift drum 86 and the shifter shaft 87 is rotatably supported on the inner wall portion 29 a of the transmission case 29, and the other end of the shift drum 86 and the shifter shaft 87 is rotatably supported on the holder 69. In addition, the shaft support structure at the inner wall portion 29a at one end of the shift drum 86 and the shifter shaft 87 is configured to be supported only by inserting one end of the shift drum 86 and the shifter shaft 87.

  The other end of the shift drum 86 protrudes outward from the holder 69, and a detent plate 88 is fastened to the other end of the shift drum 86 with a bolt 89. A plurality (six in this embodiment) of notches 90 are provided on the outer periphery of the detent plate 88 at equal intervals. Further, a detent arm 91 has a proximal end pivotally supported by a pivot 92 on the holder 69 at the side of the detent plate 88, and a distal end portion of the detent arm 91 is associated with one of the knots 90. A detent spring 94 is provided between the detent arm 91 and the holder 69, and a detent spring 94 that urges the roller 93, which can be combined, to bias the roller 93 toward the side engaged with the notch 90. Thus, the detent plate 88, the detent arm 91, and the detent spring 94 constitute a detent mechanism 95 that elastically engages the roller 93 with one of the notches 90 to hold the shift drum 86 in a predetermined rotational position. The detent mechanism 95 is disposed on the holder 69 so as to be covered with the gear case 70.

  A plurality (six in this embodiment) of driven pins 96 are arranged on the detent plate 88 at regular intervals in the circumferential direction. On the other hand, a shift spindle 97 parallel to the shift drum 86 is disposed obliquely below the shift drum 86, and one end of the shift spindle 97 passes through the inner wall portion 29a of the transmission case 29 in a freely rotatable manner. A change pedal (not shown) is attached to one end portion of the shift spindle 97 from the inner wall portion 29a. The other end of the shift spindle 97 passes through the holder 69 and is rotatably supported by the holder 69. The shift spindle 97 is externally moved to the detent plate 88 side. The base end portion of the arm 98 is fixed.

  Further, a known medium forward return mechanism 100 having a spring 99 is provided between the shift spindle 97 and the holder 69, and the shift spindle 97 and the operating arm 98 can be rotated left and right from the medium positive position shown in FIG. At the same time, the medium positive return mechanism 100 is elastically biased to the medium positive position.

  A shift arm 103 connected to the operating arm 98 via a pair of connecting shafts 101 and 102 is disposed between the operating arm 98 and the detent plate 88. The connecting shafts 101 and 102 are fixed to the operating arm 98 at a position spaced in the longitudinal direction of the operating arm 98, and extend in the longitudinal direction of the operating arm 98 to be a long hole 104 provided in the shift arm 103. , 105 are inserted through the connecting shafts 101, 102, respectively. Thus, the shift arm 103 is movable relative to the operating arm 98 within a range where the connecting shafts 101 and 102 are in contact with both ends of the long holes 104 and 105 in the longitudinal direction. In addition, both ends of the torsion spring 106 surrounding the connecting shaft 101 are in contact with the shift arm 103, and the shift arm 103 moves to the shift spindle 97 with respect to the operating arm 98 by the spring force exerted by the torsion spring 106. It is energized to the adjacent side.

  The shift arm 103 has a pair of driven pins 96, 96 sandwiching one driven pin 96 between the plurality of driven pins 96 planted on the detent plate 88 from the side opposite to the shift spindle 97. Has a pair of driving claws 103a that contact each other, and when the shift spindle 97 rotates to the left or right from the center position, one driven pin 96 of one of the driving claws 103a is pushed to detent plate 88. Is moved to the side away from the shift spindle 97, so that the other driven pin 96 gets over the other driving claw 103a, and the shift drum 86 changes the gear position by one gear position. It will rotate.

  The operating arm 98 and the shift arm 103 are also covered with the gear case 70. A cylinder 107 is attached to the gear case 70 coaxially with the input shaft 30 for driving in the axial direction a rod 52 that switches between disengagement and engagement of the clutch 38.

  Next, the operation of this embodiment will be described. An opening through which the gear transmission mechanism 33 in an assembled state can be inserted into the transmission case 29 is formed in the outer wall portion 29b of the transmission case 29 that houses the gear transmission mechanism 32. 68, and a holder 69 that is attached to the outer wall 29b of the transmission case 29 so as to close the opening 68, and an end portion of the input shaft 30 of the gear transmission mechanism 32 and the bevel gear mechanism 33 side of the output shaft 31. Is supported rotatably, and supports a driven bevel gear 72 that constitutes a part of the bevel gear mechanism 33 and is connected to the drive shaft 18 through a transmission shaft 75 so as not to be relatively rotatable, and accommodates the bevel gear mechanism 33. A gear case 70 is attached to the holder 69.

  That is, the gear transmission mechanism 32 is assembled by supporting the ends of the input shaft 30 and the output shaft 31 on the side of the bevel gear mechanism 33 on the holder 69, and the gear case 70 that covers the bevel gear mechanism 33 connected to the output shaft 31 is mounted on the holder 69. After the clearance adjustment in the state attached to 69 is completed, the holder 69 is attached to the transmission case 29, whereby the gear transmission mechanism 32 connected to the bevel gear mechanism 33 after the clearance adjustment is completed is changed to the transmission case 29. The gear transmission mechanism 32 and the bevel gear mechanism 33 are connected to each other so that they can be attached to the transmission case 29 in a state where the bevel gear mechanism 33 is connected to the output shaft 31. Therefore, in this embodiment, the shift drum 86, the shifter shaft 87, and the shift spindle 97 together with the bevel gear mechanism 33 are also included in the transmission case 29. It will be assembled.

  According to such a configuration, since the gear transmission mechanism 32 can be assembled to the transmission case 29 in a state of being connected to the bevel gear mechanism 33, the gear transmission mechanism 32 is adjusted after the clearance adjustment in the bevel gear mechanism 33 is performed. Can be assembled to the transmission case 29 together with the bevel gear mechanism 33, and the assemblability can be improved.

  The driven bevel gear 72 constitutes a part of the first to sixth gear trains G1 to G6 and is attached to the input shaft 30 for the first to sixth speed drive gears 53, 55, 57, 59, 61. , 63 is arranged such that a part of the driven bevel gear 72 is overlapped on the first speed drive gear 53 having the smallest diameter on a projection view on a plane orthogonal to the axis of the crankshaft 25. The bevel gear mechanism 33 can be arranged close to the crankshaft 25 side to concentrate the mass in the engine body 24, and the driven bevel gear 72 of the bevel gear mechanism 33 can be used as the input shaft in the gear transmission mechanism 32. Even when arranged on the 30 side, the portion of the gear case 70 that supports the driven bevel gear 72 interferes with the portion of the holder 69 that supports the end of the input shaft 30 on the bevel gear mechanism 33 side. It can be avoided.

  Further, the crankcase 14 with which the transmission case 29 is integrally provided is divided into two vertically, and the axis of the output shaft 31 is disposed on the split surface 85 of the crankcase 14, and the axis of the crankshaft 25 is arranged. Since the axis of the input shaft 30 is disposed at a position shifted downward from the dividing surface 85 between the axes of the output shaft 31, the length of the engine body 24 in the front-rear direction can be reduced, and the input shaft The lower part of the transmission M can be made compact in the width direction of the engine main body 24 by shortening the vertical distance between 30 and the dividing surface 85.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

1 is a side view of a motorcycle. It is a principal part enlarged side view of an engine main body. FIG. 3 is an enlarged cross-sectional view of the gear speed change mechanism and the bevel gear mechanism cut along line 3-3 in FIG. 2. FIG. 4 is a cross-sectional view showing the structure between the crankshaft and the input shaft of the gear transmission mechanism, taken along line 4-4 of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 6 is a sectional view taken along line 6-6 of FIG.

Explanation of symbols

14 ... crankcase 18 ... drive shaft 24 ... engine body 25 ... crankshaft 29 ... transmission case 30 ... input shaft 31 ... output shaft 32 ... gear transmission mechanism 33 ... Bevel gear mechanism 53, 55, 57, 59, 61, 63 ... Drive gear 68 ... Opening 69 ... Holder 70 ... Gear case 72 ... Driven bevel gear 85 ... -Dividing surface F ... body frame G1-G6 ... gear train P ... power unit WR ... rear wheel

Claims (3)

  A crankshaft (25) having an axis line in the vehicle width direction is rotatably supported on a crankcase (14) of an engine body (24) mounted on the vehicle body frame (F), and the crank along the vehicle traveling direction is supported. An input shaft (30) to which power is transmitted from the crank shaft (25) and an output shaft (30) parallel to the input shaft (30) are connected to a transmission case (29) connected to the rear portion of the case (14). 31) and a gear transmission mechanism (32) including a gear train (G1 to G6) of a plurality of speed stages provided between the input shaft (30) and the output shaft (31) to enable selective establishment. A bevel gear mechanism (33) is provided between the drive shaft (18) extending in a direction orthogonal to the axis of the output shaft (31) and transmitting power to the rear wheel (WR) and the output shaft (31). In the vehicle power unit, the teeth The transmission mechanism (32) and the bevel gear mechanism (33) are coupled so as to be able to be assembled to the transmission case (29) in a state where the bevel gear mechanism (33) is coupled to the output shaft (31). A power unit for a vehicle.   The transmission case (29) is provided with an opening (68) into which the gear transmission mechanism (32) in the assembled state can be inserted into the transmission case (29). The ends of the input shaft (30) and the output shaft (31) on the side of the bevel gear mechanism (33) are rotatably supported by a holder (69) that is attached to the transmission case (29) so as to be closed. The bevel gear mechanism (33) is accommodated by supporting a driven bevel gear (72) that constitutes a part of the bevel gear mechanism (33) and is connected to the drive shaft (18) so as not to be relatively rotatable. A gear case (70) is attached to the holder (69), constitutes a part of the gear train (G1 to G6) of a plurality of shift stages, and is attached to the input shaft (30) to drive gears (53, 55). , 57, 59, 61, 63) of the smallest diameter drive gear (53 Further, the driven bevel gear (72) is arranged at a position where a part of the driven bevel gear (72) is overlapped on a projection view on a plane orthogonal to the axis of the crankshaft (25). The power unit for vehicles according to claim 1.   The crankcase (14) to which the transmission case (29) is integrally connected is divided into two parts in the vertical direction, and the output shaft (31) is arranged on the dividing surface (85) of the crankcase (14). An axis is arranged, and the axis of the input shaft (30) is arranged at a position shifted downward from the dividing surface (85) between the axis of the crankshaft (25) and the axis of the output shaft (31). The vehicular power unit according to claim 1 or 2.

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