JPH062062Y2 - Key shift type transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial field of application The present invention is suitable for use in relatively small traveling work vehicles such as a walk-type lawn mower equipped with a traveling drive mechanism and a riding mower tractor equipped with a mid-mounted mower. The present invention relates to a suitable key shift type transmission.

2. Description of the Related Art As is well known, a key shift transmission is a transmission case in which a drive shaft and a transmission shaft are provided in parallel with each other, and a plurality of gears fixedly mounted on the drive shaft and a loosely fitted installation on the transmission shaft. A plurality of shift gear trains formed by meshing with a plurality of gears are provided, and the gears on the shift shaft are selectively slidable in a long groove on the outer peripheral surface of the shift shaft by a clutch projection of a shift key. It is configured to be connected to a speed change shaft, and the gears addressed to a plurality of gears on each of the above shafts are provided in an array in which the heels are in contact with each other. Are suitable.

It is also well known to provide such a key shift type transmission with a reverse gear for the reverse movement of the vehicle, and such a reverse gear is generally known, for example, in U.S. Pat. No. 4,103,566 or JP-A-61-1.
As disclosed in Japanese Patent No. 16154, a chain is wound between a sprocket wheel fixedly installed on a drive shaft and a sprocket wheel loosely fitted on a speed change shaft, and the sprocket wheel on the speed change shaft is connected to the shift key clutch described above. The projection is configured to be selectively connectable to the shift shaft. The reverse transmission train consisting of a sprocket wheel and a chain is cheaper than the reverse transmission train using gears, but the sprocket wheel has a large module when converted to gears and the reverse speed cannot be slowed down. There is also a conventional example in which an idler gear is provided on a support shaft supported by a mission case and a reverse transmission train is constituted by a gear train as disclosed in Japanese Patent Publication No. 104835.

Problems to be solved by the invention In a walk-type work vehicle such as a walk-type lawnmower equipped with a traveling drive mechanism, it is necessary to reduce the reverse vehicle speed so that the operator can follow the work vehicle moving backward while following the work vehicle. Even a passenger work vehicle is required to have a small reverse speed depending on the application. Therefore, from the economical point of view, when the reverse vehicle speed is low, the gears are used, and when the reverse speed is high, the sprocket wheel and the chain are used, and the other parts of the transmission have the same structure so as to be shared by both. However, the following problems remain.

That is, the mission case incorporating the key shift type transmission is generally formed by die-casting in two planes including the axes of a plurality of parallel shafts, as is the case with each of the above-mentioned publications, and the shaft support. It is supposed that the shaft end is held by the mating surfaces of both halves of the mission case, and machining is eliminated as much as possible after the case is cast and formed. When the reverse gear is obtained by a gear train, if the support shaft for the idler gear is supported by the mission case as in the above-mentioned Japanese Patent Laid-Open No. 60-104835, the shaft support portion for the mission is also used. When forming simultaneously with case casting and molding, the case where the reverse is obtained with the sprocket wheel and chain and the mission case are completely different specifications, and when the shaft support is formed by machining after case casting and molding, extra processing is added. Becomes

Therefore, in this invention, a reverse gear train is constructed by providing a support shaft of a reverse idler gear without supporting it in a mission case, and a reverse transmission train by a sprocket wheel and a chain is immediately provided by changing a few parts. It is an object of the present invention to provide a novel key shift type transmission capable of achieving the following.

Technical measures taken to solve the problems. Therefore, as shown in FIGS. 1 and 2, the present invention provides a drive shaft 12 and a transmission shaft 13 in a transmission case 10 in parallel with each other, and drives them. A plurality of gears 14F ₁ , 14F ₂ , 14F ₃ , 14F ₄ , 14F ₅ fixedly installed on the shaft 12.
And a plurality of gears 15F ₁ , which are loosely fitted and installed on the transmission shaft 13,
15F ₂ , 15F ₃ , 15F ₄ , 15F ₅ are provided with a plurality of gear trains of gears meshed with each other, and the gears on the gearshift shaft 13 are slidable in the long grooves 16 on the outer peripheral surface of the gearshift shafts.
The following technical measures have been taken in the key-shift type transmission 11 configured to be selectively connected to the transmission shaft 13 by the clutch projection 17a of 17.

That is, the drive shaft 12 is inserted through the two holes 19 and 20 through which the drive shaft 12 and the speed change shaft 13 are respectively inserted.
A plate 18 supported by the drive shaft 12 and the transmission shaft 13 is provided in the mission case 10, and the drive shaft 12 is attached to the plate 18.
And the support shaft 21 parallel to the speed change shaft 13 are fixed, and the drive shaft 1
The gear 14R fixedly installed on the gear 2, the idler gear 22 provided on the support shaft 21, and the gear 15R loosely fitted on the speed change shaft 13 are sequentially meshed to form a reverse gear train, and the speed change shaft 13 The above-mentioned gear 15R is selectively connected to the shift shaft 13 by the clutch projection 17a of the shift key 17 so as to obtain the reverse rotation of the shift shaft 13.

In the illustrated example, the drive shaft 12 and the speed change shaft 13 are respectively inserted into the holes 19 and 20, and the gears 14R and 15R provided on the shafts 12 and 13 are slightly protruded in the axial direction by boss protrusions 14Ra and 15Ra. Although it is inserted through the shaft 1, the holes 19 and 20 are made smaller and the shaft 1
The structure in which the holes 2 and 13 are directly inserted into the holes 19 and 20 may be adopted.

The fifth feature of the key shift type transmission 11A of the specification in which a reverse transmission train using a sprocket wheel and a chain instead of the reverse transmission gear train including the gears 14R, 22, 15R is provided.
As illustrated in the drawing, the sprocket wheels SPa and SPb are installed at the installation locations of the gears 14R and 15R, and the chain CH is wound between them.

In the transmission 11 shown in FIG. 1 and the transmission 11A shown in FIG. 5, a plate 18 having a support shaft 21 and parts such as three gears 14R, 22, 15R and two sprocket wheels SPa, SPb. And the parts such as the chain CH are different, and the other parts are completely the same.

Embodiment An embodiment shown in FIGS. 1 to 4 relates to an example in which the present invention is implemented in a transaxle type transmission for a small traveling work vehicle, and the transmission case 10 has axles 25 and 26 extending left and right. Equipped.

In the illustrated case, the speed change shaft 13 is formed as a hollow shaft, and an axle 26 on one side is provided so as to penetrate the speed change shaft 13. An intermediate shaft 27 concentrically arranged with the drive shaft 12 is also provided in the mission case 10. As shown in FIG. 2, the mission case 10 is divided and cast into upper and lower case halves, and the mating surfaces of both case halves are a plane including the axes of the shafts 12, 13, 25, 26 and 27. A support portion that supports these shafts through bearings is formed on the mating surfaces of both case halves.

As shown in FIG. 2, a supporting cylinder portion 28 extending in the vertical direction is integrally formed in the upper half of the case, and a vertical input shaft 29 extending inside and outside the mission case 10 has the supporting cylinder. It is provided so as to be supported by the portion 28. The input shaft 29 is equipped with an input pulley 30 outside the mission case 10, and a bevel gear 31 is integrally formed at the lower end. The small bevel gear 31 is meshed with a large bevel gear 32 fixedly installed on the drive shaft 12 as shown in FIG.

As shown in FIG. 1, the support shaft 21 is connected to the plate 18
One end is passed through the hole and is fixed to the plate 18 by welding. The idler gear 21 is mounted on the support shaft 21 by a ring 33.
And is retained by a retaining ring 34. On the inner peripheral surface of the boss portion of each gear 15F _{1 to} 15F ₅ on the speed change shaft 13, there are provided a plurality of (4) slots 35 into which the clutch projections 17a of the shift key 17 can be inserted, whereas The same number of slots 35 are provided on the inner peripheral surface of the boss of the gear 15R loosely fitted on the shaft 13 as shown in FIG.

A shifter sleeve 36 is slidably provided on the speed change shaft 13, and two shift keys 17 arranged in the two long grooves 16 in the illustrated example are provided on the shifter sleeve 36 at their base ends. Installed. The leaf spring 37 for urging the shift key 17 in the direction in which the clutch projection 17a thereof projects to the outside of the transmission shaft 13 has a bent portion at the base end thereof.
And is disposed on the inner bottom surface side of the long groove 16.

A small-diameter gear 38 is locked to the speed change shaft 13 at the end opposite to the gears 15F _{1 to} 15F ₅ group, and this gear 38 meshes with a large-diameter gear 39 fixedly installed on the intermediate shaft 27. Has been done. Another small gear 40 having a small diameter is fixedly installed on the intermediate shaft 27. The gear 40 has left and right axles 25, 2
6 is meshed with a large-diameter gear 41 which is loosely fitted and installed on the upper part 6. Between the gear 41 and the left and right axles 25, 26,
Left and right side clutches 42, 43 are provided.

The structures of the side clutches 42 and 43 are shown in FIGS.
Referring to the drawings, the boss portion of the gear 41 has the axle 2
An annular projecting portion 41a which is substantially in sliding contact with 5, 26 is integrally formed, and two projecting holes 60 are formed in the projecting portion 41a on the side of each axle 25, 26. Corresponding 2 holes 6
1 is formed in a cut shape from the inner end face side of each axle 25, 26, and a ball 62 is inserted and installed so as to straddle the holes 60, 61. A clutch sleeve 63 having an inner surface portion slidably contacting the overhanging portion 41a is slidably provided on the inner end portion of each axle 25, 26, and a ball 62 is provided at the inner surface portion end of each clutch sleeve 63. Slope 63 that abuts with the holes 61 of the axles 25 and 26 pulled out
a is provided.

As described above, the side clutches 42 and 43 connect the gear 41 to the axles 25 and 26 via the balls 62 when the clutch sleeve 63 prevents the balls 62 from being pulled out from the holes 61 as shown in FIG. Then, as shown in FIG. 3, when the clutch sleeve 63 is slid to the opposite side of the gear 41, the centrifugal force based on the rotation of the gear 41 causes each axle 2 to move.
The connection between the gear 41 and the axles 25, 26 is cut off by coming out of the holes 61 of 5, 5 and contacting the inclined surface 63a. When each clutch sleeve 63 is slid toward the gear 41 side, the ball 62 is pushed by the inclined surface 63a so that the side clutches 42 and 43 are inserted.

On the left and right outer surfaces of the mission case 10, left and right side brakes 45, 46 for braking the left and right axles 25, 26 are provided.
Is provided.

The transmission shown in FIGS. 1-4 is mounted on the machine body between the left and right drive wheels in a small traveling work vehicle, and the left and right drive wheels are attached to the ends of the left and right axles 25 and 26. The shifter sleeve 36 is slid on the transmission shaft 13 by a change lever (not shown), and the clutch projection 1 of the shift key 17 is moved.
The gears 15F ₁ , 15F ₂ , 15F ₃ , addressed to one by 7a,
By selectively connecting 15F ₄ or 15F ₅ to the transmission shaft 13, the vehicle can be driven forward at vehicle speeds of 1st to 5th. The clutch protrusion 17a of the shift key 17 causes the gear 1
When 5R is connected to the speed change shaft 13, the vehicle can be driven in reverse at a low speed. When the work vehicle is rotated, either side clutch 42 or 43 is disengaged depending on the direction of travel, and if necessary, the side brake 45 or 46 of that example is operated.

Effect of the Invention This invention utilizes the drive shaft 12 and the speed change shaft 13 of the key shift type transmission 11, and supports the plate 18 provided in the transmission case 10 by the side shafts 12 and 13 for the reverse gear train. Since the support shaft 21 of the idler gear 22 is fixed and no support is provided in the mission case for installing the reverse gear train, the mission case 1
It is assumed that the transmission case having the same specifications as the transmission case for the key shift type transmission using a sprocket wheel and a chain instead of the reverse gear train can be used as 0, and the plate 18 including the support shaft 21 and the three gears 14 can be used.
R, 22.15R, and other parts are replaced with two sprocket wheels and a chain wound between them. Immediately, a transmission equipped with a reverse transmission train by a sprocket wheel and a chain can be provided. Lower costs.

[Brief description of drawings]

FIG. 1 is a cross-sectional plan view of a transmission equipped with an embodiment of the present invention, FIG. 2 is a vertical cross-sectional side view, partly omitted, which is substantially along the line II-II in FIG. 1, and FIG. FIG. 4 is an enlarged cross-sectional plan view in which a portion is enlarged, FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 1, and FIG. 5 is a cross-sectional plan view showing a key shift type transmission having another structure. 10 ... Mission case, 11 ... Key shift type transmission, 12 ... Drive shaft, 13 ... Shift shaft, 14F ₁ , 14F ₂ ,
14F ₃ , 14F ₄ , 14F ₅ ... Gear, 14R ... Gear, 1
5F ₁ , 15F ₂ , 15F ₃ , 15F ₄ , 15F ₅ ... Gears,
15R ... Gear, 16 ... Long groove, 17 ... Shift key, 17a
… Clutch protrusion, 18… Plate, 19… Hole, 20…
Holes, 21 ... Support shafts, 22 ... Idler gears, 25, 26 ... Axles, 36 ... Shifter sleeves, 37 ... Leaf springs.

Claims (1)

[Scope of utility model registration request] 1. A plurality of gears 14F ₁ , 14F ₂ , 14F ₃ , 1 fixedly installed on the drive shaft 12 by providing a drive shaft 12 and a transmission shaft 13 in parallel with each other in a mission case 10.
4F _4, 14F ₅ and provided with a transmission gear train of the plurality of rows comprising a plurality of gears _{15F 1, 15F 2, 15F 3} , 15F 4, and 15F ₅ not engage that rotatably mounted on the transmission shaft 13, transmission Axis 1
In the key shift type transmission device 11 configured to selectively connect the above gear on the transmission gear shaft 3 to the transmission shaft 13 by the clutch projection 17a of the shift key 17 slidable in the long groove 16 on the outer peripheral surface of the transmission shaft, The transmission case 1 includes a plate 18 supported by the drive shaft 12 and the transmission shaft 13 through two holes 19 and 20 through which the drive shaft 12 and the transmission shaft 13 are inserted.
A gear shaft 14 fixedly mounted on the drive shaft 12 and an idler gear 22 provided on the support shaft 21. A reverse gear train is formed by sequentially meshing with a gear 15R loosely fitted on the speed change shaft 13 and the gear 15R on the speed change shaft 13 is selectively selected by the clutch projection 17a of the shift key 17 described above. A key-shift transmission that is configured to be connected to the rear shaft to obtain reverse rotation of the transmission shaft 13.