Final drive for work machine and work machine

Abstract

This final drive assembly for a work machine comprises a motor, a first input shaft, a first planetary gear mechanism, a second input shaft, a second planetary gear mechanism, a rotating body, a first clutch, and a second clutch. The first planetary gear mechanism includes a first sun gear, a first planetary gear, and a first ring gear. The first sun gear is connected to the first input shaft. The second planetary gear mechanism includes a second sun gear, a second planetary gear, and a second ring gear. The second sun gear is connected to the second input shaft. The second planetary gear is integrated with the first planetary gear. The rotating body is connected to the second ring gear. The first clutch connects the motor and the first input shaft. The second clutch connects the motor and the second input shaft.

Description

Final drive for work machine and work machine

[0001] The present disclosure relates to a final drive for a work machine and a work machine.

[0002] Some work machines are equipped with final drive assemblies. For example, the work machine disclosed in Patent Document 1 is equipped with left and right final drive assemblies. The final drive assembly includes a motor and a planetary gear mechanism. The final drive assembly reduces the rotation of the motor and transmits it.

[0003] US2021 / 179170

[0004] In order to obtain an appropriate output torque according to the rotational speed of the motor in a work machine, it is preferable that the final drive assembly be capable of multiple speed changes. However, in this case, the final drive assembly becomes larger. An object of the present disclosure is to obtain an appropriate output torque according to the rotational speed of the motor while reducing the size of the final drive assembly.

[0005] A final drive assembly for a work machine according to one aspect of the present disclosure includes a motor, a first input shaft, a first planetary gear mechanism, a second input shaft, a second planetary gear mechanism, a rotating body, a first clutch, and a second clutch. The first input shaft is arranged coaxially with the motor. The first planetary gear mechanism is arranged coaxially with the first input shaft. The first planetary gear mechanism includes a first sun gear, a first planetary gear, and a first ring gear. The first sun gear is connected to the first input shaft. The first planetary gears mesh with the first sun gear. The first ring gear meshes with the first planetary gear. The second input shaft is arranged coaxially with the first input shaft. The second planetary gear mechanism is arranged coaxially with the second input shaft. The second planetary gear mechanism includes a second sun gear, a second planetary gear, and a second ring gear. The second sun gear is connected to the second input shaft. The second planetary gears are meshed with the second sun gear. The second planetary gears are integrated with the first planetary gears. The second ring gears are meshed with the second planetary gears. The rotor is connected to the second ring gear. The first clutch connects the motor to the first input shaft. The second clutch connects the motor to the second input shaft.

[0006] In the final drive assembly for a work machine according to this aspect, the first clutch connects the motor to the first input shaft, thereby transmitting the rotation of the motor to the rotating body via the first input shaft, the first planetary gear mechanism, and the second planetary gear mechanism. The second clutch connects the motor to the second input shaft, thereby transmitting the rotation of the motor to the rotating body via the second input shaft and the second planetary gear mechanism. This provides an appropriate output torque according to the rotational speed of the motor. The first planetary gear mechanism and the second planetary gear mechanism are connected to each other because the first planetary gear and the second planetary gear are integrated. This reduces the number of parts, thereby miniaturizing the final drive assembly.

[0007] A work machine according to another aspect of the present disclosure includes a vehicle body and a travelling device. The travelling device supports the vehicle body. The travelling device includes the above-described final drive assembly for a work machine.

[0008] According to the present disclosure, an appropriate output torque according to the rotational speed of the motor can be obtained, and the final drive assembly can be made smaller.

[0009] It is a perspective view of a work machine according to an embodiment. It is a cross-sectional view taken along a vertical plane passing through an axis of a final drive assembly. It is a skeleton diagram of a final drive assembly. It is a skeleton diagram of a final drive assembly showing a driving force transmission path in a first speed. It is a skeleton diagram of a final drive assembly showing a driving force transmission path in a second speed.

[0010] A work machine according to an embodiment will now be described with reference to the drawings. Fig. 1 is a perspective view of a work machine 1 according to an embodiment. The work machine 1 according to this embodiment is a bulldozer. As shown in Fig. 1, the work machine 1 comprises a vehicle body 2, a work implement 3, and left and right traveling devices 4A, 4B.

[0011] The vehicle body 2 includes a driver's cab 5 and a power room 6. The power room 6 is disposed in front of the driver's cab 5. The upper surface of the power room 6 is inclined forward and downward. The work implement 3 is supported movably on the vehicle body 2. The work implement 3 includes a blade 7.

[0012] The left and right traveling units 4A, 4B support the vehicle body 2. The traveling unit 4A includes a crawler belt 11, a track frame 12, and a final drive assembly 13. The track frame 12 supports the crawler belt 11 via a plurality of rollers and idlers (not shown). The crawler belt 11 is wound around the final drive assembly 13. An axis Ax1 of the final drive assembly 13 extends in the left-right direction of the work machine 1. The configuration of the traveling unit 4B is similar to that of the traveling unit 4A, and therefore a description thereof will be omitted.

[0013] Fig. 2 is a cross-sectional view of the final drive assembly 13 taken along a vertical plane passing through the axis Ax1. Fig. 3 is a skeleton diagram of the final drive assembly 13. As shown in Fig. 2, the final drive assembly 13 includes a support shaft 21, a motor 22, a first input shaft 23, a first planetary gear mechanism 24, a second input shaft 25, a second planetary gear mechanism 26, a rotating body 27, a first clutch 28, and a second clutch 29.

[0014] The support shaft 21 is fixed to the truck frame 12. The support shaft 21 extends in the axial direction of the final drive assembly 13 (hereinafter simply referred to as the "axial direction"). The support shaft 21 has an internal space S1. The motor 22 is disposed in the internal space S1 of the support shaft 21. The motor 22 is disposed coaxially with the support shaft 21. The motor 22 is, for example, an electric motor. The motor 22 includes a stator 31 and a rotor 32. The stator 31 is fixed to the support shaft 21. The rotor 32 is disposed within the stator 31. The rotor 32 is supported by the support shaft 21 via bearings 33 and 34. The rotor 32 is rotatable relative to the support shaft 21.

[0015] The first input shaft 23 is disposed coaxially with the motor 22. The first input shaft 23 passes through the rotor 32 and extends in the axial direction. The first input shaft 23 is supported by the rotor 32 via a bearing 35. The first input shaft 23 is rotatable relative to the rotor 32.

[0016] The first planetary gear mechanism 24 is disposed coaxially with the first input shaft 23. The motor 22, the first planetary gear mechanism 24, and the second planetary gear mechanism 26 are disposed side by side in the axial direction. The first planetary gear mechanism 24 is disposed between the motor 22 and the second planetary gear mechanism 26 in the axial direction. The first planetary gear mechanism 24 includes a first sun gear 41, a first planetary gear 42, a first ring gear 43, and a first carrier 44.

[0017] The first sun gear 41 is connected to the first input shaft 23. The first sun gear 41 rotates integrally with the first input shaft 23. The first planetary gear 42 meshes with the first sun gear 41. The first planetary gear 42 is rotatable around the first sun gear 41. The first planetary gear 42 is supported by a rotation shaft 46 via a bearing 45. The rotation shaft 46 is supported by the first carrier 44. The first planetary gear 42 is rotatable around the rotation shaft 46. The first ring gear 43 meshes with the first planetary gear 42. The first ring gear 43 is connected to the support shaft 21. The first ring gear 43 is fixed to the support shaft 21 so as not to be rotatable.

[0018] The second input shaft 25 is disposed coaxially with the first input shaft 23. The second input shaft 25 passes through the rotor 32 and extends in the axial direction. The second input shaft 25 is rotatable relative to the rotor 32. The second input shaft 25 passes through the first input shaft 23 and extends in the axial direction. The second input shaft 25 is rotatable relative to the first input shaft 23.

[0019] The second planetary gear mechanism 26 is disposed coaxially with the second input shaft 25. The second planetary gear mechanism 26 includes a second sun gear 51, a second planetary gear 52, a second ring gear 53, and a second carrier 54. The second sun gear 51 is connected to the second input shaft 25. The second sun gear 51 rotates integrally with the second input shaft 25.

[0020] The second planetary gear 52 meshes with the second sun gear 51. The second planetary gear 52 is rotatable around the second sun gear 51. The second planetary gear 52 is disposed coaxially with the first planetary gear 42. The second planetary gear 52 is integrated with the first planetary gear 42. The second planetary gear 52 rotates around the first sun gear 41 and the second sun gear 51 integrally with the first planetary gear 42. The second planetary gear 52 is supported on the rotation shaft 46 via a bearing 55. The second planetary gear 52 is rotatable around the rotation shaft 46. The second planetary gear 52 rotates around the rotation shaft 46 integrally with the first planetary gear 42. The first carrier 44 of the first planetary gear mechanism 24 and the second carrier 54 of the second planetary gear mechanism 26 are rotatable integrally with the rotation shaft 46 around the axis line Ax1.

[0021] The diameter of the second planetary gear 52 is larger than the diameter of the first planetary gear 42. However, the diameter of the second planetary gear 52 may be smaller than or the same as the diameter of the first planetary gear 42. The number of teeth of the second planetary gear 52 is greater than the number of teeth of the first planetary gear 42. The second carrier 54 supports the rotation shaft 46. The second ring gear 53 meshes with the second planetary gear 52. Note that in the drawings, only some of the multiple first planetary gears 42 and only some of the multiple second planetary gears 52 are shown.

[0022] The rotating body 27 is disposed coaxially with the support shaft 21. The rotating body 27 is supported by the support shaft 21 via bearings 37 and 38. The rotating body 27 is rotatable relative to the support shaft 21. The rotating body 27 includes a sprocket 61 and a sprocket hub 62. The crawler belt 11 is wound around the sprocket 61. The sprocket hub 62 is connected to the sprocket 61. The sprocket 61 protrudes radially from the outer peripheral surface of the sprocket hub 62. The first planetary gear mechanism 24 and the second planetary gear mechanism 26 are disposed within the sprocket hub 62. The second ring gear 53 is connected to the inner surface of the sprocket hub 62. The sprocket hub 62 rotates integrally with the second ring gear 53.

[0023] When first clutch 28 is engaged, it connects motor 22 and first input shaft 23. As a result, first input shaft 23 rotates integrally with rotor 32. When first clutch 28 is disengaged, it disconnects motor 22 and first input shaft 23. As a result, first input shaft 23 is able to rotate freely relative to rotor 32. First clutch 28 is disposed within rotor 32. First clutch 28 includes a plurality of clutch plates fixed to rotor 32 and a plurality of clutch plates fixed to first input shaft 23.

[0024] When the second clutch 29 is engaged, it connects the motor 22 and the second input shaft 25. As a result, the second input shaft 25 rotates integrally with the rotor 32. When the second clutch 29 is disengaged, it disconnects the motor 22 from the second input shaft 25. As a result, the second input shaft 25 is able to rotate freely relative to the rotor 32. The second clutch 29 is disposed within the rotor 32. The second clutch 29 includes a plurality of clutch plates fixed to the rotor 32 and a plurality of clutch plates fixed to the second input shaft 25.

[0025] 4 is a skeleton diagram of the final drive assembly 13 showing the drive force transmission path in first gear. As shown in FIG. 4, in first gear, the first clutch 28 is disengaged and the second clutch 29 is engaged. In this state, the motor 22 is connected to the second input shaft 25. The rotation from the motor 22 is transmitted to the rotating body 27 via the second input shaft 25, the second sun gear 51, the second planetary gear 52, and the second ring gear 53. As a result, the rotation of the motor 22 is transmitted to the rotating body 27 at the reduction ratio of first gear, causing the sprocket 61 to rotate.

[0026] 5 is a skeleton diagram of the final drive assembly 13 showing the drive force transmission path in second gear. In second gear, the first clutch 28 is engaged and the second clutch 29 is disengaged. In this state, the motor 22 is connected to the first input shaft 23. Rotation from the motor 22 is transmitted to the rotating body 27 via the first input shaft 23, the first sun gear 41, the first planetary gear 42, the second planetary gear 52, and the second ring gear 53. As a result, the rotation of the motor 22 is transmitted to the rotating body 27 at a reduction ratio of second gear that is smaller than that of first gear, causing the sprocket 61 to rotate.

[0027] In the final drive assembly 13 for a work machine according to the present embodiment described above, the reduction ratio can be switched between first speed and second speed by switching the engagement of the first clutch 28 and the second clutch 29. This makes it possible to obtain an appropriate output torque according to the rotational speed of the motor 22. Furthermore, the first planetary gear mechanism 24 and the second planetary gear mechanism 26 are connected to each other by integrating the first planetary gear 42 and the second planetary gear 52. This reduces the number of parts, thereby making the final drive assembly 13 more compact.

[0028] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0029] The work machine 1 is not limited to a bulldozer, and may be other machines such as a shovel, wheel loader, grader, or dump truck. The structures or arrangements of the motor 22, first planetary gear mechanism 24, second planetary gear mechanism 26, first clutch 28, or second clutch 29 are not limited to those in the above embodiment and may be changed. For example, the first clutch 28 and the second clutch 29 may be arranged outside the rotor 32. The motor 22 may be a hydraulic motor. The number of teeth of the second planetary gear 52 may be smaller than the number of teeth of the first planetary gear 42.

[0030] According to the present disclosure, an appropriate output torque according to the rotational speed of the motor can be obtained, and the final drive assembly can be made smaller.

[0031] 1: Work machine, 13: Final drive assembly, 21: Support shaft, 22: Motor, 23: First input shaft, 24: First planetary gear mechanism, 25: Second input shaft, 26: Second planetary gear mechanism, 27: Rotor, 28: First clutch, 29: Second clutch, 32: Rotor, 41: First sun gear, 42: First planetary gear, 43: First ring gear, 51: Second sun gear, 52: Second planetary gear, 53: Second ring gear, 61: Sprocket, 62: Sprocket hub

Claims

1. A final drive assembly for a work machine comprising: a motor; a first input shaft arranged coaxially with the motor; a first planetary gear mechanism arranged coaxially with the first input shaft, the first planetary gear mechanism including a first sun gear connected to the first input shaft, a first planetary gear meshing with the first sun gear, and a first ring gear meshing with the first planetary gear; a second input shaft arranged coaxially with the first input shaft; a second planetary gear mechanism arranged coaxially with the second input shaft, the second planetary gear mechanism including a second sun gear connected to the second input shaft, a second planetary gear meshing with the second sun gear and integrated with the first planetary gear, and a second ring gear meshing with the second planetary gear; a rotating body connected to the second ring gear; a first clutch connecting the motor to the first input shaft; and a second clutch connecting the motor to the second input shaft.

2. A final drive assembly for a work machine according to claim 1, wherein the second input shaft extends axially through the first input shaft.

3. A final drive assembly for a work machine according to claim 1, wherein the motor includes a rotor, and the first clutch and the second clutch are disposed within the rotor.

4. A final drive assembly for a work machine according to claim 1, wherein the rotating body includes a sprocket and a sprocket hub connected to the sprocket, and the first planetary gear mechanism and the second planetary gear mechanism are disposed within the sprocket hub.

5. A final drive assembly for a work machine according to claim 4, wherein the first ring gear is connected to the support shaft, and the second ring gear is connected to the inner surface of the sprocket hub.

6. The final drive assembly for a work machine according to claim 1, further comprising a support shaft that rotatably supports the rotating body, and the motor is disposed within the support shaft.

7. A work machine comprising: a vehicle body; and a traveling device that supports the vehicle body, wherein the traveling device includes a final drive assembly according to any one of claims 1 to 6.

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