Work machine motor drive assembly and work machine

Abstract

A work machine motor drive assembly according to the present invention comprises a motor, a fixed case, a high-speed rotation mechanism, a housing, and a low-speed rotation mechanism. The fixed case includes a first internal space and a lubricating oil passage. The lubricating oil passage supplies lubricating oil to the first internal space. The high-speed rotation mechanism is provided in the first internal space. The high-speed rotation mechanism is connected to the motor. The high-speed rotation mechanism is lubricated via a dry sump system by the lubricating oil supplied through the lubricating oil passage. The housing includes a second internal space in which lubricating oil is sealed. The housing is rotatably supported by the fixed case. The low-speed rotation mechanism is provided in the second internal space. The low-speed rotation mechanism reduces the speed of rotation by the high-speed rotation mechanism and transmits the rotation to the housing. The low-speed rotation mechanism is lubricated by an oil bath of the lubricating oil in the second internal space.

Description

Motor drive assembly for a working machine and a working machine

[0001] The present disclosure relates to a motor drive assembly for a working machine and a working machine.

[0002] The motor drive assembly for a working machine includes a motor assembly and a final drive assembly. The final drive assembly is connected to the motor assembly. The final drive assembly includes a high-speed rotation mechanism and a low-speed rotation mechanism. For example, the motor drive assembly of Patent Document 1 includes a brake as a high-speed rotation mechanism and a planetary gear mechanism as a low-speed rotation mechanism. The brake is connected to the motor assembly. The planetary gear mechanism is connected to a sprocket. The rotation from the motor assembly is transmitted to the planetary gear mechanism via the brake, decelerated, and then transmitted to the sprocket.

[0003] U.S. Patent No. 12,083,412

[0004] In the motor drive assembly as described above, the high-speed rotation mechanism rotates at a higher speed than the low-speed rotation mechanism. However, both the high-speed rotation mechanism and the low-speed rotation mechanism are lubricated by an oil bath. Therefore, in the high-speed rotation mechanism that rotates at a high speed, the stirring loss due to the lubricating oil increases. The object of the present disclosure is to reduce the stirring loss due to the lubricating oil in the motor drive assembly for a working machine.

[0005] A motor drive assembly for a work machine according to one aspect of the present disclosure comprises a motor, a fixed case, a high-speed rotation mechanism, a housing, and a low-speed rotation mechanism. The fixed case includes a first internal space and a lubrication oil passage. The lubrication oil passage supplies lubricating oil to the first internal space. The high-speed rotation mechanism is located within the first internal space. The high-speed rotation mechanism is connected to the motor. The high-speed rotation mechanism is lubricated in a dry-sump manner by lubricating oil supplied through the lubrication oil passage. The housing includes a second internal space filled with lubricating oil. The housing is rotatably supported by the fixed case. The low-speed rotation mechanism is located within the second internal space. The low-speed rotation mechanism reduces the rotation of the high-speed rotation mechanism and transmits it to the housing. The low-speed rotation mechanism is lubricated by an oil bath of lubricating oil in the second internal space.

[0006] In the motor drive assembly for work machines according to this embodiment, the low-speed rotation mechanism is lubricated by an oil bath of lubricating oil in the second internal space, while the high-speed rotation mechanism is lubricated in a dry-sump manner by lubricating oil supplied through the lubricating oil passage. As a result, agitation loss due to lubricating oil is reduced in the high-speed rotation mechanism. Consequently, agitation loss due to lubricating oil is reduced in the motor drive assembly for work machines.

[0007] Other aspects of the present disclosure of work machines include a body and a running gear. The running gear supports the body. The running gear includes the motor drive assembly described above.

[0008] According to this disclosure, stirring losses due to lubricating oil are reduced in a motor drive assembly for a work machine.

[0009] This is a perspective view of a work machine according to an embodiment. This is a block diagram showing the configuration of the work machine. This is a cross-sectional view of a motor drive assembly. This is a skeleton diagram of a motor drive assembly. This is an enlarged cross-sectional view of a motor drive assembly. This is a cross-sectional view of a motor drive assembly showing the area filled with lubricating oil. This is a cross-sectional view of a motor drive assembly according to a first modified example. This is a skeleton diagram of a motor drive assembly according to a first modified example. This is a cross-sectional view of a motor drive assembly according to a second modified example. This is a skeleton diagram of a motor drive assembly according to a second modified example. This is a cross-sectional view of a motor drive assembly according to a third modified example. This is a skeleton diagram of a motor drive assembly according to a third modified example. This is a cross-sectional view of a motor drive assembly according to a fourth modified example. This is a skeleton diagram of a motor drive assembly according to a fourth modified example. This is a cross-sectional view of a motor drive assembly according to a fifth modified example. This is a skeleton diagram of a motor drive assembly according to a fifth modified example.

[0010] The following description of the working machine according to the embodiment will be made with reference to the drawings. Figure 1 is a perspective view of the working machine 1 according to the embodiment. Figure 2 is a block diagram showing the configuration of the working machine 1. The working machine 1 according to this embodiment is a bulldozer. As shown in Figure 1, the working machine 1 comprises a body 2, a working machine 3, and left and right traveling devices 4 and 5. The body 2 includes a driver's cab 6 and a power room 7. The power room 7 is located in front of the driver's cab 6. The working machine 3 is operably supported relative to the body 2. The working machine 3 includes a blade 8.

[0011] The left and right running gears 4 and 5 support the vehicle body 2. The left running gear 4 includes a track 11, a motor drive assembly 12, and a track frame 13. The track frame 13 supports the track 11 via several road wheels (not shown) and idlers. The track 11 is wound around the motor drive assembly 12. The motor drive assembly 12 is attached to the track frame 13. The axis Ax1 of the motor drive assembly 12 extends in the left-right direction of the work machine 1. In the following description, the direction parallel to axis Ax1 is defined as the axial direction.

[0012] As shown in Figure 2, the motor drive assembly 12 includes a motor assembly 21 and a final drive assembly 22. The motor assembly 21 is connected to the final drive assembly 22. In this embodiment, the motor assembly 21 is an electric motor. The final drive assembly 22 is located outside the motor assembly 21 in the axial direction.

[0013] The final drive assembly 22 includes a fixed case 23, a final drive housing 24, and a sprocket 25. The final drive assembly 22 is positioned coaxially with the motor assembly 21. As will be described in detail later, the final drive housing 24 is rotatably supported by the fixed case 23. The sprocket 25 is fixed to the final drive housing 24. The track 11 is wound around the sprocket 25. The motor assembly 21 is attached to the fixed case 23.

[0014] The right-side running gear 5 includes the track 14 shown in Figure 1, the track frame 15 shown in Figure 2, and the motor drive assembly 16. The motor drive assembly 16 includes the motor assembly 17 and the final drive assembly 18. The track 14, track frame 15, and motor drive assembly 16 of the right-side running gear 5 have the same configuration as the track 11, track frame 13, and motor drive assembly 12 of the left-side running gear 4 described above. The configuration of running gear 5 is the same as that of running gear 4, and therefore its description is omitted.

[0015] As shown in Figure 2, the work machine 1 includes an engine 31, a generator 32, a PTO 33, a lubrication pump 34, a scavenging pump 35, an oil tank 36, and an oil cooler 37. The engine 31 drives the generator 32. The generator 32 generates electricity when driven by the engine 31. The electricity generated by the generator 32 is supplied to the motor assemblies 21 and 17 of the travel devices 4 and 5 via an inverter / converter (not shown). This drives the motor assemblies 21 and 17, which in turn move the work machine 1.

[0016] The PTO 33 distributes the driving force of the engine 31 to the lubrication pump 34 and the scavenging pump 35. The lubrication pump 34 is driven by the driving force of the engine 31 and discharges lubricating oil. The lubricating oil is supplied from the oil tank 36 through the lubrication pump 34 and the oil cooler 37 to the motor drive assemblies 12 and 16. The scavenging pump 35 is driven by the driving force of the engine 31 and draws lubricating oil from the motor drive assemblies 12 and 16. The lubricating oil returns from the motor drive assemblies 12 and 16 through the scavenging pump 35 to the oil tank 36.

[0017] Next, the motor drive assembly 12 will be described. Figure 3 is a cross-sectional view of the motor drive assembly 12. Figure 4 is a skeleton view of the motor drive assembly 12. As shown in Figures 3 and 4, the motor assembly 21 is arranged coaxially with the final drive assembly 22 and the fixed case 23.

[0018] As shown in Figure 3, the motor assembly 21 includes a motor 40 and a motor case 41. The motor case 41 is fixed to the fixed case 23. The motor 40 includes a stator 42, a rotor 43, and a motor shaft 44. The stator 42 and rotor 43 are located inside the motor case 41. The stator 42 is fixed to the inner surface of the motor case 41. The motor shaft 44 is fixed to the rotor 43. The rotor 43 is rotatable relative to the stator 42. The motor shaft 44 and rotor 43 are rotatably supported by the motor case 41. The motor shaft 44 is located coaxially with the fixed case 23. The motor shaft 44 extends in the axial direction. The motor shaft 44 protrudes outward from the motor case 41 in the axial direction.

[0019] As shown in Figures 3 and 4, the final drive assembly 22 includes a central shaft 45, a high-speed rotation mechanism 46, and a low-speed rotation mechanism 47. The central shaft 45 is coaxially positioned with respect to the fixed case 23. The central shaft 45 extends in the axial direction. The central shaft 45 is rotatably supported by the fixed case 23 via bearings 48 and 49.

[0020] The high-speed rotation mechanism 46 rotates at a higher speed than the low-speed rotation mechanism 47. The high-speed rotation mechanism 46 is connected to the motor shaft 44. The high-speed rotation mechanism 46 reduces the rotation of the motor shaft 44 and transmits it to the low-speed rotation mechanism 47. The low-speed rotation mechanism 47 rotates at a lower speed than the high-speed rotation mechanism 46. The low-speed rotation mechanism 47 is connected to the final drive housing 24. The low-speed rotation mechanism 47 reduces the rotation of the high-speed rotation mechanism 46 and transmits it to the final drive housing 24. The high-speed rotation mechanism 46 includes a first planetary gear mechanism 51 and a brake 52. The low-speed rotation mechanism 47 includes a second planetary gear mechanism 53 and a third planetary gear mechanism 54.

[0021] The first planetary gear mechanism 51 is arranged coaxially with the central shaft 45. The first planetary gear mechanism 51 is located outside the motor assembly 21 in the axial direction. The first planetary gear mechanism 51 is connected to the motor shaft 44. The first planetary gear mechanism 51 is located between the motor assembly 21 and the brake 52 in the axial direction. The first planetary gear mechanism 51 includes a first sun gear 55, a first planetary gear 56, a first ring gear 57, and a first carrier 58.

[0022] The first sun gear 55 is fixed to the motor shaft 44. The first sun gear 55 rotates integrally with the motor shaft 44. The first planetary gear 56 meshes with the first sun gear 55. The first planetary gear 56 is capable of revolving around the first sun gear 55. The first planetary gear 56 is supported by the first carrier 58 so that it can rotate on its own axis. The first ring gear 57 meshes with the first planetary gear 56. The first ring gear 57 is connected to the fixed case 23. The first ring gear 57 is fixed to the fixed case 23 so that it cannot rotate. The first carrier 58 rotates around the first sun gear 55 along with the revolving of the first planetary gear 56. The first carrier 58 is fixed to the central shaft 45. The central shaft 45 rotates integrally with the first carrier 58.

[0023] The brake 52 is located outside the first planetary gear mechanism 51 in the axial direction. The brake 52 is connected to the first carrier 58 of the first planetary gear mechanism 51 via the central shaft 45. The brake 52 brakes the rotation of the central shaft 45, thereby braking the sprocket 25. Figure 5 is an enlarged cross-sectional view of the motor drive assembly 12. As shown in Figure 5, the brake 52 includes a brake hub 59, a plurality of brake discs 60, 61, a piston 62, and a biasing member 63. The brake hub 59 is fixed to the central shaft 45. The brake hub 59 rotates integrally with the central shaft 45.

[0024] The multiple brake discs 60, 61 include a rotor disc 60 and a stator disc 61. The rotor disc 60 is connected to the brake hub 59 so as to be non-rotatable and axially movable relative to the brake hub 59. The rotor disc 60 rotates integrally with the brake hub 59. The stator disc 61 is positioned axially opposite to the rotor disc 60. The stator disc 61 is supported by a fixed case 23 so as to be axially movable.

[0025] The piston 62 is positioned axially opposite the brake discs 60 and 61. The piston 62 is supported by a fixed case 23 so as to be movable in the axial direction. The biasing member 63 is, for example, a coil spring. Alternatively, the biasing member 63 may be another type of spring, such as a leaf spring. The biasing member 63 biases the piston 62 in a direction that presses against the brake discs 60 and 61.

[0026] The fixed case 23 includes a hydraulic chamber 64. When hydraulic fluid is supplied to the hydraulic chamber 64, the piston 62 is driven. When hydraulic fluid is not supplied to the hydraulic chamber 64, the piston 62 presses against the brake discs 60 and 61 by the biasing force of the biasing member 63. As a result, the rotor disc 60 and the stator disc 61 engage with each other, and the brake 52 brakes the central shaft 45. When hydraulic fluid is supplied to the hydraulic chamber 64, the piston 62 moves away from the brake discs 60 and 61 against the biasing force of the biasing member 63. Also, a spring (not shown) is placed between the stator discs 61 that biases them in a direction that pulls them apart from each other. As a result, the rotor disc 60 and the stator disc 61 separate from each other, and the brake 52 releases the central shaft 45. In other words, the brake 52 is a negative-type brake in which the braking state is released by the supply of hydraulic fluid.

[0027] As shown in Figure 3, the second planetary gear mechanism 53 is arranged coaxially with the central shaft 45. The second planetary gear mechanism 53 is connected to the first planetary gear mechanism 51 via the central shaft 45. The second planetary gear mechanism 53 is located outside the brake 52 in the axial direction. The second planetary gear mechanism 53 includes a second sun gear 65, a second planetary gear 66, a second ring gear 67, and a second carrier 68.

[0028] The second sun gear 65 is fixed to the central axis 45. The second sun gear 65 rotates integrally with the central axis 45. The second planetary gear 66 meshes with the second sun gear 65. The second planetary gear 66 is capable of revolving around the second sun gear 65. The second planetary gear 66 is supported by the second carrier 68 so that it can rotate on its own axis. The second ring gear 67 meshes with the second planetary gear 66. The second ring gear 67 is fixed to the final drive housing 24. The second ring gear 67 rotates together with the final drive housing 24. The second carrier 68 rotates around the second sun gear 65 along with the revolving second planetary gear 66.

[0029] The third planetary gear mechanism 54 is arranged coaxially with the central axis 45. The third planetary gear mechanism 54 is connected to the second planetary gear mechanism 53. In the axial direction, the third planetary gear mechanism 54 is located outside the brake 52. In the axial direction, the third planetary gear mechanism 54 is located inside the second planetary gear mechanism 53. The third planetary gear mechanism 54 includes a third sun gear 69, a third planetary gear 70, and a third ring gear 71.

[0030] The third sun gear 69 is positioned on the outer circumference of the central axis 45. The third sun gear 69 includes a hole 72, which extends axially through the third sun gear 69. The central axis 45 extends through the hole 72 of the third sun gear 69. The third sun gear 69 is rotatable relative to the central axis 45. The third sun gear 69 is fixed to the second carrier 68 of the second planetary gear mechanism 53. The third sun gear 69 rotates together with the second carrier 68.

[0031] The third planetary gear 70 meshes with the third sun gear 69. The third planetary gear 70 is supported by the fixed case 23 so as to be able to rotate on its own axis but not be able to revolve around the third sun gear 69. The third ring gear 71 meshes with the third planetary gear 70. The third ring gear 71 is fixed to the final drive housing 24. The third ring gear 71 rotates together with the final drive housing 24.

[0032] In the final drive assembly 22 described above, the first planetary gear mechanism 51 reduces the rotation of the motor shaft 44 and transmits it to the central shaft 45. The second planetary gear mechanism 53 and the third planetary gear mechanism 54 reduce the rotation of the central shaft 45 and transmit it to the final drive housing 24. In detail, the rotation of the motor shaft 44 is transmitted to the central shaft 45 in the first planetary gear mechanism 51 via the first sun gear 55, the first planetary gear 56, and the first carrier 58.

[0033] The rotation of the central shaft 45 is transmitted to the final drive housing 24 via the second sun gear 65, second planetary gear 66, and second ring gear 67 in the second planetary gear mechanism 53. The revolution of the second planetary gear 66 causes the second carrier 68 to rotate, and the rotation of the second carrier 68 is transmitted to the final drive housing 24 via the third sun gear 69, third planetary gear 70, and third ring gear 71 in the third planetary gear mechanism 54. As a result, the sprocket 25 rotates together with the final drive housing 24.

[0034] As shown in Figure 3, the fixed case 23 includes a fixed case housing 73 and a partition wall 74. The fixed case housing 73 includes a cylindrical portion 75 and a flange portion 76. The flange portion 76 protrudes radially outward from the cylindrical portion 75. The cylindrical portion 75 extends in the axial direction. The cylindrical portion 75 supports the final drive housing 24 via bearings 77 and 78.

[0035] As shown in Figure 5, the fixed case housing 73 has a first internal space S1, a first opening 79, and a second opening 80. The first planetary gear mechanism 51 and the brake 52 are located within the first internal space S1. The first opening 79 and the second opening 80 communicate with the first internal space S1. The first opening 79 opens inward in the axial direction. The second opening 80 opens outward in the axial direction. The central shaft 45 extends through the second opening 80.

[0036] The partition wall 74 is located within the first internal space S1 between the first planetary gear mechanism 51 and the brake 52. The partition wall 74 is a separate component from the fixed case housing 73. The first internal space S1 includes a first region A1 and a second region A2. The partition wall 74 divides the first internal space S1 into the first region A1 and the second region A2. The first planetary gear mechanism 51 is located in the first region A1. The brake 52 is located in the second region A2.

[0037] The partition wall 74 includes a first wall portion 81, a second wall portion 82, and a third wall portion 83. The first wall portion 81 is located radially outward of the first planetary gear mechanism 51. The first wall portion 81 is attached to the first opening 79 of the fixed case housing 73. The first ring gear 57 described above is provided on the inner circumference of the first wall portion 81. The second wall portion 82 extends radially inward from the first wall portion 81, passing between the first planetary gear mechanism 51 and the brake 52. The third wall portion 83 extends axially from the second wall portion 82 toward the brake 52. The third wall portion 83 supports the central shaft 45 via a bearing 49.

[0038] As shown in Figure 3, the final drive housing 24 has a second internal space S2. The cylindrical portion 75 of the fixed case housing 73 is located within the second internal space S2. The second planetary gear mechanism 53 and the third planetary gear mechanism 54 are located within the second internal space S2. The fixed case housing 73 separates the first internal space S1 and the second internal space S2.

[0039] As shown in Figure 5, oil seals 84 and 85 are installed in the second opening 80 of the fixed case housing 73. The oil seals 84 and 85 are positioned between the second opening 80 and the central axis 45. The oil seals 84 and 85 are positioned between the first internal space S1 and the second internal space S2. The oil seals 84 and 85 seal the space between the first internal space S1 and the second internal space S2.

[0040] As shown in Figure 3, floating seals 86 and 87 are positioned between the flange portion 76 of the fixed case housing 73 and the final drive housing 24. The floating seals 86 and 87 seal the second internal space S2 from the external space of the final drive assembly 22.

[0041] Next, the lubrication of the motor drive assembly 12 will be described. As shown in Figure 5, the fixed case 23 includes a lubrication oil passage 88 and a scavenging oil passage 89. The lubrication oil passage 88 is an oil passage for supplying lubricating oil to the first internal space S1. The lubricating oil from the lubrication pump 34 described above is supplied to the lubrication oil passage 88. The scavenging oil passage 89 is an oil passage for suctioning lubricating oil from the first internal space S1. The lubricating oil in the first internal space S1 is suctioned through the scavenging oil passage 89 by the scavenging pump 35 described above. The first planetary gear mechanism 51 and the brake 52, which are located in the first internal space S1, are lubricated in a dry sump system (forced lubrication system) by the lubricating oil supplied through the lubrication oil passage 88.

[0042] More specifically, the lubrication oil passage 88 extends through the first wall portion 81, the second wall portion 82, and the third wall portion 83. The lubrication oil passage 88 includes the first lubrication oil passage 90, the second lubrication oil passage 91, and the third lubrication oil passage 92. The first lubrication oil passage 90 extends axially through the first wall portion 81. The second lubrication oil passage 91 extends radially through the second wall portion 82. The third lubrication oil passage 92 extends axially through the third wall portion 83. The third lubrication oil passage 92 communicates with the second region A2.

[0043] The partition wall 74 includes a throttle 93. The throttle 93 is provided in the second wall portion 82. The throttle 93 communicates with the lubricating oil passage 88 and the first region A1. The lubricating oil passage 88 communicates with the first region A1 via the throttle 93. The lubricating oil from the lubricating pump 34 is supplied to the second region A2 through the first lubricating oil passage 90, the second lubricating oil passage 91, and the third lubricating oil passage 92. Thereby, the brake 52 is lubricated.

[0044] The lubricating oil from the lubricating pump 34 is supplied to the first region A1 through the first lubricating oil passage 90, the second lubricating oil passage 91, and the throttle 93. Thereby, the first planetary gear mechanism 51 is lubricated. Also, by supplying the lubricating oil to the first planetary gear mechanism 51 via the throttle 93, it is possible to suppress an excessive amount of lubrication from being supplied to the first planetary gear mechanism 51. Thereby, the agitation loss of the lubricating oil in the first planetary gear mechanism 51 is reduced.

[0045] The scavenging oil passage 89 extends through the first wall portion 81 and the second wall portion 82. The scavenging oil passage 89 includes a first scavenging oil passage 94 and a second scavenging oil passage 95. The first scavenging oil passage 94 extends axially through the first wall portion 81. The second scavenging oil passage 95 extends radially through the second wall portion 82. The second scavenging oil passage 95 communicates with the second region A2. The lubricating oil supplied to the first internal space S1 through the lubricating oil passage 88 is returned to the oil tank 36 through the scavenging oil passage 89. As described above, the first planetary gear mechanism 51 and the brake 52 are lubricated by a dry sump method (forced lubrication method) using the lubricating pump 34 and the scavenging pump 35.

[0046] The second internal space S2 is sealed from the outside of the final drive housing 24 by the oil seals 84, 85 and the floating seals 86, 87. As shown in FIG. 6, lubricating oil 98 is enclosed in the second internal space S2. In FIG. 6, the hatched area indicates the lubricating oil filled in the second internal space S2. For ease of understanding, the hatching of other components is omitted in FIG. 6. The lubricating oil from the lubricating pump 34 described above is not supplied to the second internal space S2. The second planetary gear mechanism 53 and the third planetary gear mechanism 54 disposed in the second internal space S2 are lubricated by the oil bath of the lubricating oil in the second internal space S2.

[0047] In the motor drive assembly 12 according to the present embodiment described above, the low-speed rotation mechanism 47 is lubricated by the oil bath of the lubricating oil in the second internal space S2, while the high-speed rotation mechanism 46 is lubricated by the dry sump method with the lubricating oil supplied through the lubricating oil passage 88. Therefore, the stirring loss due to the lubricating oil in the high-speed rotation mechanism 46 is reduced. Thereby, in the motor drive assembly 12, the stirring loss due to the lubricating oil is reduced.

[0048] As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention.

[0049] The working machine 1 is not limited to a bulldozer, and may be other machines such as an excavator, a wheel loader, a grader, or a dump truck. The configurations of the traveling devices 4 and 5 are not limited to those of the above embodiment and may be changed. For example, the traveling devices 4 and 5 may include tires instead of crawlers. The structure or arrangement of the motor assembly 21, the high-speed rotation mechanism 46, or the low-speed rotation mechanism 47 is not limited to those of the above embodiment and may be changed.

[0050] For example, Figure 7 is a cross-sectional view of a motor drive assembly 12A according to a first modified example. Figure 8 is a skeleton view of a motor drive assembly 12A according to a first modified example. As shown in Figures 7 and 8, in the first modified example, the first planetary gear mechanism 51 is located inside the motor case 41. That is, the first planetary gear mechanism 51 is included in the motor assembly 21. The high-speed rotation mechanism 46 includes a brake 52 connected to the motor assembly 21. Other structures of the motor drive assembly 12A according to the first modified example are the same as those of the motor drive assembly 12 according to the embodiment described above.

[0051] Figure 9 is a cross-sectional view of the motor drive assembly 12B according to the second modified example. Figure 10 is a skeleton view of the motor drive assembly 12B according to the second modified example. As shown in Figures 9 and 10, in the second modified example, the motor shaft 44 is fixed to the central shaft 45. The central shaft 45 rotates integrally with the motor shaft 44.

[0052] The high-speed rotation mechanism 46 includes a brake 52 similar to that of the embodiments described above. The central shaft 45 extends through the brake hub 59. The central shaft 45 is rotatable relative to the brake hub 59. The low-speed rotation mechanism 47 includes a planetary gear mechanism 100. The planetary gear mechanism 100 is located outside the brake 52 in the axial direction. The planetary gear mechanism 100 includes a sun gear 101, a first planetary gear 102, a first ring gear 103, a second planetary gear 104, a second ring gear 105, and a carrier 106.

[0053] The sun gear 101 is fixed to the central axis 45. The sun gear 101 rotates integrally with the central axis 45. The first planetary gear 102 meshes with the sun gear 101. The first planetary gear 102 is capable of orbiting the sun gear 101. The first planetary gear 102 is supported by the carrier 106 so as to be able to rotate. The first ring gear 103 meshes with the first planetary gear 102. The first ring gear 103 is fixed to the final drive housing 24. The first ring gear 103 rotates together with the final drive housing 24.

[0054] The second planetary gear 104 is integrated with the first planetary gear 102. The number of teeth of the second planetary gear 104 is different from the number of teeth of the first planetary gear 102. For example, the number of teeth of the second planetary gear 104 is less than the number of teeth of the first planetary gear 102. Alternatively, the number of teeth of the second planetary gear 104 may be more than the number of teeth of the first planetary gear 102. The second planetary gear 104 revolves around the sun gear 101 integrally with the first planetary gear 102. The second planetary gear 104 is supported by the carrier 106 so as to be able to rotate. The second planetary gear 104 rotates integrally with the first planetary gear 102. The second ring gear 105 meshes with the second planetary gear 104. The second ring gear 105 is fixed to the fixed case housing 73. The carrier 106 is connected to the brake hub 59. The brake hub 59 is rotatable around the central axis 45. The brake hub 59 rotates together with the carrier 106. Other structures of the motor drive assembly 12B according to the second modification are the same as those of the motor drive assembly 12 according to the above-described embodiment.

[0055] In the motor drive assembly 12B according to the second modified example, the rotation of the motor 40 is transmitted to the final drive housing 24 via the central shaft 45, sun gear 101, first planetary gear 102, and first ring gear 103. As a result, the sprocket 25 rotates together with the final drive housing 24. The second planetary gear 104 also revolves around the sun gear 101 together with the first planetary gear 102. The brake hub 59 rotates together with the second planetary gear 104. Therefore, the sprocket 25 is braked by the brake 52, which in turn brakes the revolving second planetary gear 104.

[0056] Figure 11 is a cross-sectional view of the motor drive assembly 12C according to the third modified example. Figure 12 is a skeleton view of the motor drive assembly 12C according to the third modified example. As shown in Figures 11 and 12, in the third modified example, the high-speed rotation mechanism 46 includes a parallel shaft gear 110 instead of the first planetary gear mechanism 51 of the embodiment described above. The parallel shaft gear 110 reduces the rotation of the motor shaft 44 and transmits it to the brake 52.

[0057] The parallel-axis gear 110 includes a first gear 111 and a second gear 112. The first gear 111 is fixed to the motor shaft 44. The second gear 112 meshes with the first gear 111. The second gear 112 is fixed to the central shaft 45. The other structure of the motor drive assembly 12C according to the third modification is the same as that of the motor drive assembly 12 according to the above-described embodiment.

[0058] Figure 13 is a cross-sectional view of the motor drive assembly 12D according to the fourth modification. Figure 14 is a skeleton view of the motor drive assembly 12D according to the fourth modification. As shown in Figures 13 and 14, in the fourth modification, the brake 52 is located inside the motor assembly 21 in the axial direction. The brake hub 59 is fixed to the motor shaft 44. The first sun gear 55 of the first planetary gear mechanism 51 is fixed to the motor shaft 44. Other structures of the motor drive assembly 12D according to the fourth modification are the same as those of the motor drive assembly 12 according to the above-described embodiment. In the motor drive assembly 12D according to the fourth modification, the brake 52 brakes the rotation of the motor shaft 44. As a result, the sprocket 25 is braked.

[0059] Figure 15 is a cross-sectional view of the motor drive assembly 12E according to the fifth modified example. Figure 16 is a skeleton view of the motor drive assembly 12E according to the fifth modified example. As shown in Figures 15 and 16, the motor drive assembly 12E according to the fifth modified example further includes a clutch 120. The clutch 120 is positioned between the first planetary gear mechanism 51 and the motor 40. The clutch 120 is positioned inside the motor case 41. The clutch 120 switches the connection and disconnection between the motor shaft 44 and the high-speed rotation mechanism 46.

[0060] More specifically, the motor shaft 44 includes a first motor shaft 44A and a second motor shaft 44B. The first motor shaft 44A is fixed to the rotor 43. The first motor shaft 44A rotates integrally with the rotor 43. The second motor shaft 44B extends axially through the first motor shaft 44A. The second motor shaft 44B is rotatable relative to the first motor shaft 44A. The second motor shaft 44B is fixed to the first sun gear 55 of the first planetary gear mechanism 51. The clutch 120 releases the second motor shaft 44B from the first motor shaft 44A in the disengaged state. The clutch 120 connects the second motor shaft 44B to the first motor shaft 44A in the engaged state. Other structures of the motor drive assembly 12E according to the fifth modified example are the same as those of the motor drive assembly 12 according to the embodiment described above.

[0061] When the brake 52 is not applied, the clutch 120 is engaged, connecting the motor shaft 44 to the first planetary gear mechanism 51. As a result, the rotation of the motor shaft 44 is transmitted to the first planetary gear mechanism 51, causing the sprocket 25 to rotate. When the brake 52 is applied, the clutch 120 is disengaged, releasing the motor shaft 44 from the first planetary gear mechanism 51. This suppresses the deceleration of the motor shaft 44.

[0062] According to this disclosure, stirring losses due to lubricating oil are reduced in a final drive assembly for a working machine.

[0063] 1: Working machine, 2: Vehicle body, 4, 5: Running gear, 12: Motor drive assembly, 21: Motor assembly, 23: Fixed case, 24: Final drive housing, 46: High-speed rotation mechanism, 47: Low-speed rotation mechanism, 51: First planetary gear mechanism (first rotation mechanism), 52: Brake (second rotation mechanism), 74: Bulkhead, 81: First wall section, 82: Second wall section, 83: Third wall section, 84, 85: Oil seal, 88: Lubrication oil passage, 89: Scavenging oil passage, 90: First lubrication oil passage, 91: Second lubrication oil passage, 92: Third lubrication oil passage, 93: Restriction, 94: First scavenging oil passage, 95: Second scavenging oil passage, A1: First area, A2: Second area, S1: First internal space, S2: Second internal space

Claims

1. A motor drive assembly for a work machine, comprising: a motor; a fixed case including a first internal space and a lubrication oil passage for supplying lubricating oil to the first internal space; a high-speed rotation mechanism disposed within the first internal space, connected to the motor, and lubricated in a dry-sump manner by lubricating oil supplied through the lubrication oil passage; a housing having a second internal space filled with lubricating oil and rotatably supported by the fixed case; and a low-speed rotation mechanism disposed within the second internal space, which reduces the rotation of the high-speed rotation mechanism and transmits it to the housing, and is lubricated by an oil bath of lubricating oil in the second internal space.

2. The motor drive assembly according to claim 1, wherein the fixed case further includes a scavenging oil passage for drawing lubricating oil from the first internal space.

3. The motor drive assembly according to claim 1, further comprising an oil seal disposed between the first internal space and the second internal space.

4. The motor drive assembly according to claim 1, wherein the high-speed rotation mechanism includes a first rotation mechanism connected to the motor and a second rotation mechanism connected to the first rotation mechanism, the first internal space includes a first region where the first rotation mechanism is arranged and a second region where the second rotation mechanism is arranged, the fixed case includes a partition wall separating the first region and the second region, the lubrication oil passage is provided in the partition wall and communicates with the second region, and the partition wall includes a throttling that communicates with the lubrication oil passage and the first region.

5. The motor drive assembly according to claim 4, wherein the first rotating mechanism is a planetary gear mechanism, and the second rotating mechanism is a brake.

6. The motor drive assembly according to claim 1, wherein the high-speed rotation mechanism includes a planetary gear mechanism connected to the motor, and a brake located outside the planetary gear mechanism in the axial direction of the fixed case and connected to the planetary gear mechanism, the fixed case includes a partition wall located between the planetary gear mechanism and the brake in the first internal space, the partition wall includes a first wall portion located radially outward of the planetary gear mechanism, a second wall portion extending radially inward from the first wall portion through the space between the planetary gear mechanism and the brake, and a third wall portion extending axially from the second wall portion toward the brake, and the lubrication oil passage extends through the first wall portion, the second wall portion and the third wall portion.

7. The motor drive assembly according to claim 6, wherein the lubrication passage includes a first lubrication passage extending axially through the first wall, a second lubrication passage extending radially through the second wall, and a third lubrication passage extending axially through the third wall.

8. The motor drive assembly according to claim 6, wherein the fixed case further includes a scavenging oil passage for drawing lubricating oil from the first internal space, the scavenging oil passage extending through the first wall and the second wall.

9. The motor drive assembly according to claim 8, wherein the scavenging oil passage includes a first scavenging oil passage extending axially through the first wall and a second scavenging oil passage extending radially through the second wall.

10. The motor drive assembly according to claim 1, wherein the high-speed rotation mechanism includes a first planetary gear mechanism connected to the motor and a brake connected to the first planetary gear mechanism, and the low-speed rotation mechanism includes a second planetary gear mechanism connected to the brake and a third planetary gear mechanism connected to the second planetary gear mechanism.

11. The motor drive assembly according to claim 1, wherein the high-speed rotation mechanism includes a brake connected to the motor, and the low-speed rotation mechanism includes a first planetary gear mechanism connected to the brake, and a second planetary gear mechanism connected to the first planetary gear mechanism.

12. The motor drive assembly according to claim 1, wherein the high-speed rotation mechanism includes a first planetary gear mechanism connected to the motor, and the low-speed rotation mechanism includes a second planetary gear mechanism connected to the first planetary gear mechanism, and a third planetary gear mechanism connected to the second planetary gear mechanism.

13. A work machine comprising a vehicle body and a running device supporting the vehicle body, wherein the running device includes a motor drive assembly according to any one of claims 1 to 12.

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