JP3921170B2 - Rear wheel drive device for work vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technology of a rear wheel drive device for a work vehicle such as a tractor. More specifically, the present invention relates to the technology of the final reduction mechanism of the rear wheel drive device.
[0002]
[Prior art]
Conventionally, a traveling power transmission mechanism of a work vehicle such as a tractor transmits engine power to a rear wheel drive device via a main clutch, a main transmission mechanism, and an auxiliary transmission mechanism (see, for example, Patent Document 1). .
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 3-14729
[Problems to be solved by the invention]
Although the above technique can be arranged stepwise by a plurality of gears and shafts and stored in the direction of the wheel rim, the support structure of the shaft becomes complicated and the number of parts increases. Therefore, as shown in FIG. 4, an internal-tooth type final reduction mechanism is conceivable. This final reduction mechanism 120 is disposed in the rim 132 of the rear wheel 102 and is connected to the drive shaft 151 that is a transmission shaft. A final pinion gear 121 is fixed, and an internal gear 122 is fitted and fixed to the wheel shaft 123 by a spline. The power of the drive shaft 151 is decelerated by the final reduction mechanism 120 and transmitted to the wheel shaft 123 to drive the rear wheel 102. The final reduction mechanism 120 is covered with a case cover 118 and a final case 117.
[0005]
However, since the final pinion gear 121 is cantilevered on the drive shaft 151 in the final reduction mechanism 120 of the rear wheel drive device, the deflection of the drive shaft 151 increases when the load on the final pinion gear 121 increases. There was a problem of getting bigger.
On the other hand, since the internal gear 122 of the final reduction mechanism 120 is fitted and fixed to the wheel shaft 123 by a spline, the teeth of the final pinion gear 121 and the internal gear 122 are affected by the aging of the spline portion (because of play). There is a risk that the contact will deteriorate and the gears may be damaged.
Further, in order to solve the above problems, even if the final pinion gear 121 or the internal gear 122 has a larger tooth width, or the spline portion of the internal gear 122 is lengthened to increase the strength, the width of the final reduction mechanism 120 can be increased. As a result, the tread becomes wider and the entire vehicle becomes larger.
Therefore, in this embodiment, the final reduction mechanism is made compact and the tread is narrow by improving the tooth contact of the gears (final pinion gear 121 and internal gear 122) in the final reduction mechanism to increase the strength of the gears. Provide a compact work vehicle.
[0006]
[Means for Solving the Problems]
The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.
[0007]
In a rear wheel drive device for a work vehicle that transmits power from an engine (6) to a rear wheel (2) via a transmission, a differential device (14), and a final reduction mechanism (20), the final reduction mechanism (20 ) Is disposed in the rim (32) of the rear wheel (2), and the final reduction mechanism (20) is fixed to a drive shaft (51) connected to the output side of the transmission case (9). And an internal gear (22) fixed to the wheel shaft (23). The internal gear (22) forms a ring-shaped groove (22a) on the inner side surface, and the outside of the pinion gear (21). The bearing (91) is fitted to the end of the drive shaft (51), the bearing (91) is fitted into the groove (22a) of the internal gear (22), and the bearing (91 ) Between the outer peripheral surface (22c) of the groove (22a) A clearance is provided, and the inner peripheral surface (22b) of the groove (22a) is disposed at a position where the outer ring of the bearing (91) rolls, and the fitting portion between the internal gear (22) and the wheel shaft (23). When the internal gear (22) tries to incline due to the backlash of the spline part of the shaft, the outer ring of the bearing (91) comes into contact with the inner peripheral surface (22b) of the groove (22a), and the inclination of the internal gear (22) Is regulated .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the invention will be described.
1 is an overall schematic view of a tractor according to an embodiment of the present invention, FIG. 2 is a plan sectional view showing a rear wheel drive device, FIG. 3 is a side view showing the rear wheel drive device, and FIG. 4 is a reference rear wheel drive device. FIG.
[0009]
First, a schematic configuration of a tractor 10 that is an embodiment of a work vehicle including a rear wheel drive device according to the present invention will be described.
As shown in FIG. 1, an engine 6 is disposed in a bonnet 3 at the front of the machine, the engine 6 is covered with the bonnet 3, and a handle 4 serving as steering means is provided on a dashboard 44 at the rear of the bonnet 3. Protruding. A lever such as a main transmission lever (not shown) protrudes from the side of the dashboard 44 and a seat 5 is disposed behind the handle 4. Fenders 41 and 41 are disposed on the side of the seat 5, and a lops (safety frame) 42 is disposed on the rear part of the fenders 41 and 41. Further, a step 43 is arranged below the dashboard 44, and a clutch pedal 45, a brake pedal, and the like are arranged.
[0010]
Also, front wheels 1 and 1 are supported on both sides of the front part of the machine, and rear wheels 2 and 2 are supported on both sides of the rear part. A mission case 9 is disposed below the seat seat 5, and a three-point link type work machine mounting device 47 for mounting various work machines is attached to the rear of the mission case 9. A PTO shaft (not shown) protrudes from the rear surface of the transmission case 9 so that the work machine can be driven.
A front wheel power take-out case is provided at the front lower part of the transmission case 9, and power is transmitted to the front axle case through the transmission shaft 49 in front of the front wheel power take-out case, and the front wheel 1 supported by the front axle case can be driven. The configuration is as follows.
The rear wheels 2 and 2 are mounted such that the height relative to the vehicle body can be changed, and the vehicle body ground height is set to a desired height according to the field to be used and according to the work content such as the culm transplanting operation. It can be set to.
[0011]
The driving force from the engine 6 is transmitted from the output shaft of the engine 6 to an HST (hydraulic continuously variable transmission) serving as a main transmission disposed in the transmission case 9 via a damper or a clutch (not shown). . Then, as shown in FIG. 2, power is transmitted from the HST to the differential device 14 of the rear wheel via a sub-transmission device and a drive shaft (not shown), and from the differential device 14 to the differential shafts 15 and 15 and the transmission shaft. The rear wheels 2 and 2 are driven through certain drive shafts 51 and 51, the final speed reduction mechanisms 20 and 20, and the like.
The differential shaft 15, the drive shaft 51, the final reduction mechanism 20, the rear wheel 2 and the like are symmetrically configured, so that the differential shaft 15, the final reduction mechanism 20, the drive shaft 51, the rear wheel on the left side in the traveling direction are configured. 2 etc. will be described, and the right side will be omitted.
[0012]
As shown in FIG. 2, the differential shaft 15, the drive shaft 51, and the final reduction mechanism 20 that protrude from the transmission case 9 to the left and right sides are covered with a rear axle case 52, a final case 17, and a case cover 18. , Sealed. The rear axle case 52 has one side (inner side) fixed to the transmission case 9 by fixing means 8 such as bolts, and the other side (outer side) is fixed to one side (inner side) of the final case 17. ing. A case cover 18 is attached to the other side (outside) of the final case 17.
The final case 17 is formed in a substantially U shape in a plan sectional view, and covers the inner side surface of the final reduction mechanism 20. The outer surface of the final reduction mechanism 20 is covered with the case cover 18.
The rear axle case 52 is formed in an L shape in plan view, and the inner side surface is fixed to the side surface of the mission case 9. The rear portion of the rear axle case 52 is formed in a pipe shape extending in the left-right direction and covers the drive shaft 51. In the front portion of the rear axle case 52, a differential shaft 15 protruding from the transmission case 9 and a brake device 16 attached to the differential shaft 15 are disposed. The rear axle case 52 and the final case 17 are formed in a U shape in plan view.
[0013]
As shown in FIG. 2, the brake device 16 is disposed on the outer side of the differential device 14. In the brake device 16, the brake is operated by pressing the disk 16 a fixed to the outer end of the differential shaft 15 and the disk fitted to the rear axle case 52 by pressing the contact member 16 b. It is configured. The contact member 16b is linked to a brake lever 16c disposed outside the rear axle case 52. The brake lever 16c is a brake pedal (not shown) disposed on the step 43. )) Via a wire or the like, and when the brake pedal is operated, the brake lever 16c rotates, slides the contact member 16b, and presses the contact member 16b against the disk 16a. Thus, the rotation of the differential shaft 15 is braked.
Further, one end of an elastic member 16d such as a spring is attached to the contact member 16b, and when the brake device 16 is not operated, the contact member 16b is elastic so that the contact member 16b does not contact the disc 16a. The contact member 16b is urged in the direction opposite to the disk 16a by the member 16d.
[0014]
The differential shaft 15 is arranged in the left-right direction and protrudes outward from the differential device 14 in the mission case 9. The differential shaft 15 is pivotally supported by a bearing 61 fixed to the transmission case 9 and a bearing 62 fixed to the rear axle case 52. A first fixed gear 53 is fitted and fixed on the middle portion of the differential shaft 15 by a spline. The first fixed gear 53 is disposed in the rear axle case 52 between the differential device 14 and the brake device 16, that is, between the bearings 61 and 62.
The first fixed gear 53 meshes with the second fixed gear 54. The second fixed gear 54 is fitted and fixed to the inner end of the drive shaft 51 by a spline. The first fixed gear 53 and the second fixed gear 54 transmit the rotational speed at the same speed with substantially the same number of teeth. However, when the vehicle height is not changed, the number of teeth of the first fixed gear 53 is small, and the number of teeth of the second fixed gear 54 is increased to reduce the speed.
The drive shaft 51 is disposed in the left-right direction at the rear portion of the rear axle case 52. The outer end of the drive shaft 51 protrudes from the rear axle case 52 and is inserted into the final case 17.
A final pinion gear 21 constituting the final reduction mechanism 20 is fixed to a portion of the drive shaft 51 inserted into the final case 17, that is, an outer end portion of the drive shaft 51. Or it is molded integrally.
The drive shaft 51 is mounted in the rear axle case 52, and is a bearing 63 disposed on the outer side of the second fixed gear 54, and a bearing 64 fixed to the outer end of the rear axle case 52. These are pivotally supported by a bearing 65 fixed to the inner end of the final case 17. A bearing 91 described later is press-fitted into the outer end of the drive shaft 51.
[0015]
Next, the final deceleration mechanism will be described.
The final reduction mechanisms 20 and 20 drive the rear wheels 2 and 2 by decelerating the rotation after shifting the output from the engine 6 to an appropriate rotation number, and are provided in the vicinity of the rear wheels 2 and 2. ing.
The final reduction gears 20 and 20 include the final pinion gear 21, an internal gear 22 that meshes with the final pinion gear 21, a wheel shaft 23 that is an axle that pivotally supports the internal gear 22, and the like. Covered by a case cover 18.
The final case 17 and the case cover 18 are formed in a circular shape in a side view. A boss portion 18a is formed in the central portion of the case cover 18, and the wheel shaft 23 is inserted into the boss portion 18a. A boss portion 17a is also formed at the center of the final case 17, and one end of the wheel shaft 23 is rotatably supported by the boss portion 17a via a bearing 66. The drive shaft 51 is inserted through a through hole.
[0016]
The rear wheel 2 is formed by attaching a tire to a rear wheel rim 32 fixed to the outer periphery of a disk 31, and the disk 31 is bolted to a flange 23 b formed on the outer end of the wheel shaft 23.・ It is fixed at 33... And the rear wheel 2 is rotated integrally with the wheel shaft 23. The wheel shaft 23 includes a shaft portion 23a and a flange 23b. The flange 23b is arranged outwardly from the boss 18a of the case cover 18 as a circular shape when viewed from the side, and the shaft 23a is fixed to the bearing 66 fixed to the final case 17 and the case cover 18. The bearing 67 is rotatably supported by the bearing 67. An oil seal 28 is interposed between the outer end of the shaft portion 23a and the boss portion 18a to prevent water or the like from entering. The shaft portion 23 a is covered with the final case 17 and the case cover 18.
A spline 23c is formed between the bearing 66 and the bearing 67 on the shaft portion 23a, and the internal gear 22 is fitted on the spline 23c. A U groove 23d is formed on the outer periphery of the shaft portion 23a at the outer end of the spline 23c, and a retaining ring 26 for preventing the wheel shaft 23 from coming off is attached to the U groove 23d. Further, a collar 27 is fitted on the outer shaft portion 23 a of the internal gear 22, and the bearing 67 is disposed so as to abut on the outer surface of the collar 27. With this configuration, the axial movement of the internal gear 22 is restricted to prevent the wheel shaft 23 from coming off, and positioning is also performed.
[0017]
The internal gear 22 has a concave shape in cross-section, forms a boss at the center, and is spline-fitted onto the shaft 23a as described above, and forms a tooth on the inner surface of the outer ring. The internal teeth 22d mesh with the final pinion gear 21 to transmit the rotation of the drive shaft 51 to the final pinion gear 21, and from the final pinion gear 21 to the wheel shaft 23 via the internal gear 22. Thus, the power transmitted from the engine 6 via the transmission is decelerated and transmitted to the rear wheel 2.
Further, a ring-shaped groove 22 a is formed on the inner side surface of the internal gear 22 and is disposed on the outer side of the final pinion gear 21 (so as to be opposed), and a bearing 91 is provided at the tip of the drive shaft 51. The inner ring side of the bearing is fixed by press fitting, and the bearing 91 is inserted into the groove 22a. When the final pinion gear 21 is not loaded, the bearing 91 contacts the inner peripheral surface 22b of the groove 22a and does not contact the outer peripheral surface 22c (or does not contact the inner peripheral surface 22b, but the outer peripheral surface And the drive shaft 51 is supported rotatably with respect to the groove 22a.
[0018]
With such a configuration, when a load is applied to the final pinion gear 21 during work or the like, the outer ring of the bearing 91 press-fitted into the tip of the final pinion gear 21 rotates in contact with the inner peripheral surface 22b of the groove 22a of the internal gear 22. . Therefore, the final pinion gear 21 is supported at both ends, and the deflection of the drive shaft 51 can be reduced to reduce the load.
Further, if the internal gear 22 is inclined by the play of the spline portion of the internal gear 22, the outer ring of the bearing 91 and the inner peripheral surface 22b of the groove 22a are in contact with each other, the inclination of the internal gear 22 is restricted, and both ends are supported. Similar to the support, the two-point support of the spline portion and the groove 22a is provided, and the strength can be increased.
By comprising in this way, the support rigidity of the final pinion gear 21 and the internal gear 22 goes up, both the tooth | gear contact states are improved, and an intensity | strength improvement can be aimed at.
[0019]
Thus, the ring-shaped groove 22a is formed on the inner side surface of the internal gear 22, the bearing 91 provided at the tip of the drive shaft 51 is fitted into the groove 22a, and the bearing 91 is inserted into the outer peripheral surface 22c of the groove 22a. Is disposed at a position where the outer ring of the bearing 91 rolls on the inner circumferential surface 22b of the groove 22a, so that the support rigidity of the final pinion gear 21 and the inner gear 22 is increased. The tooth contact state is improved, and the strength can be increased. Therefore, the final pinion gear 21 and the internal gear 22 can be made thin, and the final reduction mechanism can be made compact. In addition, a compact work vehicle having a narrow tread can be configured.
[0020]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0021]
In a rear wheel drive device for a work vehicle that transmits power from an engine (6) to a rear wheel (2) via a transmission, a differential device (14), and a final reduction mechanism (20), the final reduction mechanism (20 ) Is disposed in the rim (32) of the rear wheel (2), and the final reduction mechanism (20) is fixed to a drive shaft (51) connected to the output side of the transmission case (9). And an internal gear (22) fixed to the wheel shaft (23). The internal gear (22) forms a ring-shaped groove (22a) on the inner side surface, and the outside of the pinion gear (21). The bearing (91) is fitted to the end of the drive shaft (51), the bearing (91) is fitted into the groove (22a) of the internal gear (22), and the bearing (91 ) Between the outer peripheral surface (22c) of the groove (22a) Provided the gap, the inner peripheral surface of the groove (22a) and (22b) is disposed at a position outer race of the bearing (91) to roll, the inner fitting portion of the gear (22) and the wheel shaft (23) When the internal gear (22) tries to incline due to the backlash of the spline, the outer ring of the bearing (91) comes into contact with the inner peripheral surface (22b) of the groove (22a), and the inclination of the internal gear (22) because There is restricted, raise the support rigidity of the pinion and the internal gear, as well as reduce the burden of the transmission shaft, is improved state per two teeth, you are possible to increase the strength. Further, by increasing the rigidity of both gears, the final reduction mechanism can be made compact and a compact work vehicle with a narrow tread can be constructed.
[Brief description of the drawings]
FIG. 1 is an overall schematic view of a tractor according to an embodiment of the present invention.
FIG. 2 is a plan sectional view showing a rear wheel drive device.
FIG. 3 is a side view showing a rear wheel drive device.
FIG. 4 is a plan sectional view showing a reference rear wheel drive device.
[Explanation of symbols]
2 Rear wheel 6 Engine 9 Mission case 14 Differential device 20 Final reduction mechanism 21 Final pinion gear (pinion gear)
22 Internal gear 22a Groove 23 Wheel shaft (axle)
32 Rim 51 Drive shaft (transmission shaft)
91 Bearing

Claims (1)

In a rear wheel drive device for a work vehicle that transmits power from an engine (6) to a rear wheel (2) via a transmission, a differential device (14), and a final reduction mechanism (20), the final reduction mechanism (20 ) Is disposed in the rim (32) of the rear wheel (2), and the final reduction mechanism (20) is fixed to a drive shaft (51) connected to the output side of the transmission case (9). And an internal gear (22) fixed to the wheel shaft (23). The internal gear (22) forms a ring-shaped groove (22a) on the inner side surface, and the outside of the pinion gear (21). The bearing (91) is fitted to the end of the drive shaft (51), the bearing (91) is fitted into the groove (22a) of the internal gear (22), and the bearing (91 ) Between the outer peripheral surface (22c) of the groove (22a) A clearance is provided, and the inner peripheral surface (22b) of the groove (22a) is disposed at a position where the outer ring of the bearing (91) rolls, and the fitting portion between the internal gear (22) and the wheel shaft (23). When the internal gear (22) tries to incline due to the backlash of the spline part of the shaft, the outer ring of the bearing (91) comes into contact with the inner peripheral surface (22b) of the groove (22a), and the inclination of the internal gear (22) There the rear-wheel drive system for a working vehicle, characterized in that it is regulated.

Images