Running gear for work vehicles

Abstract

A traveling device (11) comprises: a coupling (38) that joins a motor shaft (14) and a rotating shaft (15) together; a coupling housing (46) that fits on an outer peripheral surface of the coupling (38); a coupling oil passage (43) that is provided in the coupling (38) to supply a lubricating oil (L) to spline joints (39A), (40A) between the motor shaft (14) and the rotating shaft (15) and the coupling (38); and a housing oil passage (47) that is provided in the coupling housing (46) to guide some of the lubricating oil (L) to the coupling oil passage (43). The coupling housing (46) has a reservoir (50) storing the lubricating oil (L) that is supplied to the spline joints (39A), (40A) between the motor shaft (14) and rotating shaft (15) and the coupling (38). The oil reservoir (50) is shaped to have a larger capacity in a portion located on the radially upper side of the coupling housing (46).

Description

[Technical Field]

[0001] The present disclosure relates to a traveling device that is suitable for use in a work vehicle having wheels, such as a dump truck. [Background technology]

[0002] A travel device provided on a wheeled work vehicle, such as a dump truck, includes an electric motor provided on the vehicle body, a motor shaft that outputs rotation of the electric motor, a rotating shaft to which the rotation of the motor shaft is transmitted, a speed reduction mechanism that reduces the rotation of the rotating shaft and transmits it to the wheels, and a coupling that connects the motor shaft to the rotating shaft. The coupling and the motor shaft, and the coupling and the rotating shaft are each connected by a spline connection. For this reason, lubricating oil is constantly supplied to the spline connection between the motor shaft and the rotating shaft, and the coupling, preventing wear at the spline connection.

[0003] In this way, the spline joint between two components joined by a spline connection is usually lubricated with a lubricant. For example, in the invention of Patent Document 1, lubricating oil is supplied to the spline joint between the rotating shaft and the reduction mechanism, and an oil seal that slides on the outer circumferential surface of the rotating shaft prevents the lubricating oil from flowing into the electric motor (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-360726 Summary of the Invention

[0005] However, in work vehicles equipped with large electric motors, such as dump trucks, the large-diameter motor shaft rotates at high speed, making it difficult to seal the electric motor with lubricating oil using an oil seal that slides against the outer periphery of the motor shaft. Meanwhile, if a lubricant such as grease is sealed in the spline connection, there is a problem that wear particles generated from the spline connection accumulate and cause fretting wear. Furthermore, the spline connection must be periodically lubricated, which creates a maintenance burden.

[0006] An object of the present invention is to provide a traveling device for a work vehicle that is capable of properly lubricating the joints between the motor shaft and the rotating shaft and the coupling.

[0007] The present invention relates to a motor provided on the body of a work vehicle having wheels, a motor shaft that outputs rotation of the motor, a rotating shaft to which rotation of the motor shaft is transmitted, a speed reduction mechanism that reduces the rotation of the rotating shaft and transmits it to the wheels, a lubricating oil circulation circuit for supplying lubricating oil to the speed reduction mechanism, a cylindrical coupling that connects the motor shaft and the rotating shaft, a coupling housing provided on the motor and having a fitting portion that slidably fits onto the outer peripheral surface of the coupling, coupling oil passages provided on the coupling that supply lubricating oil to a connecting portion between the motor shaft and the coupling and a connecting portion between the rotating shaft and the coupling, and and a housing oil passage provided in the coupling housing, which branches off a portion of the lubricating oil flowing through the lubricating oil circulation circuit and leads it to the coupling oil passage. The coupling housing is provided with an oil reservoir that connects the housing oil passage and the coupling oil passage while covering the outer periphery of the coupling, and that stores the lubricating oil that is supplied to the connection between the motor shaft and the coupling and the connection between the rotating shaft and the coupling through the coupling oil passage, and the oil reservoir is shaped so that the capacity of the portion located radially above the coupling housing is larger than the capacity of the portion located radially below.

[0008] According to the present invention, the lubricating oil stored in the portion of the oil reservoir in the coupling housing that has a shape that increases the capacity flows smoothly downward due to its own weight. This allows the lubricating oil to be smoothly supplied to the joint between the motor shaft and the coupling and the joint between the rotating shaft and the coupling through the coupling oil passage, thereby ensuring proper lubrication of these joints. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a left side view showing a dump truck to which a traveling device according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a rear view of the dump truck seen from the rear. [Figure 3] 3 is a cross-sectional view of the rear wheel side traveling device as seen from the direction of arrows III-III in FIG. 1. [Figure 4] FIG. 4 is an enlarged view showing the motor shaft, the rotating shaft, the coupling, the coupling housing, etc. in FIG. 3. [Figure 5] FIG. 2 is an enlarged view showing the main parts of a coupling, a coupling oil passage, a coupling housing, a housing oil passage, a discharge oil passage, and the like. [Figure 6] FIG. 3 is a cross-sectional view showing the coupling alone. [Figure 7] 7 is a cross-sectional view of a splined connection between a motor shaft and a coupling, as viewed from the direction of arrows VII-VII in FIG. 5. [Figure 8] FIG. 2 is an exploded view showing a motor shaft, a rotating shaft, a coupling, a coupling housing, and the like in an exploded state. [Figure 9] 9 is a cross-sectional view of the coupling, the coupling oil passage, the coupling housing, the housing oil passage, the oil reservoir, etc., as viewed from the direction of arrows IX-IX in FIG. 5. [Figure 10] FIG. 4 is an enlarged cross-sectional view of an open end of a coupling oil passage. [Figure 11] FIG. 10 is a cross-sectional view taken in the same position as FIG. 9, showing a first modified example of an oil reservoir. [Figure 12]FIG. 10 is an enlarged cross-sectional view showing a second modified example of the large-diameter opening end of the coupling oil passage. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A travel device for a work vehicle according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings, taking as an example a case where the travel device is applied to a rear-wheel drive dump truck.

[0011] In FIG. 1, the dump truck 1 is configured to include a body 2 having a sturdy frame structure, a vessel (cargo bed) 3 mounted on the body 2 so as to be able to be raised and lowered, a cab 5 provided at the front of the body 2, and left and right front wheels 6 and left and right rear wheels 7 as wheels.

[0012] The vessel 3 is formed as a large container for carrying heavy loads such as crushed stone, and the rear bottom of the vessel 3 is connected to the rear end of the vehicle body 2 via a connecting pin 4 or the like so that it can be raised and lowered (tilted). A hood 3A that covers a cab 5 from above is integrally provided on the upper front side of the vessel 3. The cab 5 is provided at the front of the vehicle body 2, positioned below the hood 3A. The cab 5 forms a driver's cab, and inside the cab 5, a driver's seat, a steering handle, multiple operating levers (none of which are shown), etc. are provided.

[0013] The left and right front wheels 6 are rotatably mounted on the front side of the vehicle body 2 (only the left front wheel is shown). The left and right front wheels 6 constitute steering wheels that are steered by the driver. The left and right rear wheels 7 are rotatably mounted on the rear side of the vehicle body 2. The left and right rear wheels 7 constitute driving wheels of the dump truck 1, and are rotationally driven integrally with the wheel mounting sleeve 17 by the traveling device 11 shown in FIG. 3. The rear wheels 7 are configured to include two rows of tires 7A made up of dual-wheel tires, and rims 7B disposed radially inward of the tires 7A.

[0014] The engine 8 is located below the cab 5 and is provided inside the vehicle body 2. The engine 8 is configured by, for example, a diesel engine, and rotates an electric motor 13, a hydraulic pump (not shown), and other components that are mounted on the vehicle body 2. Pressurized oil discharged from the hydraulic pump is supplied to a hoist cylinder 9, a steering cylinder (not shown) for power steering, and other components.

[0015] The hoist cylinders 9 are provided between the vehicle body 2 and the vessel 3. The hoist cylinders 9 are located between the front wheels 6 and the rear wheels 7 and are arranged on both the left and right sides of the vehicle body 2. The hoist cylinders 9 expand and contract in the vertical direction as pressure oil is supplied and discharged from the hydraulic pump, and raise and lower (tilt) the vessel 3 around the connecting pin 4.

[0016] The rear wheel axle housing 10 is provided at the rear of the vehicle body 2. The axle housing 10 is a hollow cylinder extending in the left-right direction, and is attached to the rear of the vehicle body 2 via left and right rear wheel suspensions 10A. On both the left and right sides of the axle housing 10, there are provided running devices 11 that drive the left and right rear wheels 7, respectively.

[0017] The traveling devices 11 are located on both the left and right sides of the axle housing 10 and are provided for the left and right rear wheels 7, respectively. As shown in Figure 3, the traveling devices 11 are configured to include a spindle 12, an electric motor 13, a rotating shaft 15, a wheel mounting case 17, a reduction mechanism 21, a coupling 38, a coupling housing 46, and a lubricating oil circulation circuit 51. The traveling devices 11 reduce the rotation speed of the rotating shaft 15 using the reduction mechanism 21, and rotate the left and right rear wheels 7, which serve as drive wheels, with a large rotational torque.

[0018] The spindle 12 is attached to both the left and right sides of the axle housing 10. The spindle 12 is formed as a stepped cylinder extending in the axial direction (left-right direction) and has a tapered section 12A, an intermediate cylindrical section 12B, and a small-diameter cylindrical section 12C. The tapered section 12A has a tapered shape that gradually reduces in diameter from one axial side of the spindle 12 (the axle housing 10 side) to the other axial side, and is attached to the end of the axle housing 10 using multiple bolts 12D. The intermediate cylindrical section 12B is formed integrally with the reduced-diameter side of the tapered section 12A and extends axially. The small-diameter cylindrical section 12C has an outer diameter smaller than that of the intermediate cylindrical section 12B and is formed integrally with the tip side of the intermediate cylindrical section 12B.

[0019] A plurality of motor mounting seats 12E protruding radially inward are provided on one axial side of the tapered portion 12A, and an electric motor 13 is mounted on the motor mounting seats 12E. An annular flange portion 12F protruding radially outward is provided on the outer periphery of the tapered portion 12A, and a wet brake 35 (described later) is mounted on the flange portion 12F.

[0020] Meanwhile, the tip of small diameter cylindrical portion 12C is an open end, and a cylindrical protrusion 33A of second-stage carrier 33 (described later) is splined to its inner periphery. An annular inner protrusion 12G that protrudes radially inward is integrally formed on the inner periphery of an axially intermediate portion of small diameter cylindrical portion 12C, and a bearing 16 (described later) is attached to inner protrusion 12G. Furthermore, a radial hole 12H that penetrates vertically (radially of small diameter cylindrical portion 12C) is drilled in the lower portion of small diameter cylindrical portion 12C, and a tip 52A of a suction pipe 52 (described later) is inserted into this radial hole 12H.

[0021] The electric motor 13 for driving is disposed within the axle housing 10 and the tapered portion 12A of the spindle 12. A plurality of mounting flanges 13A are provided on the outer periphery of the electric motor 13, and the mounting flanges 13A are attached to the motor mounting seat 12E of the spindle 12 (tapered portion 12A) using bolts or the like.

[0022] The motor shaft 14 protrudes from the electric motor 13. When supplied with electric power from a generator (not shown) mounted on the vehicle body 2, the electric motor 13 rotates the motor shaft 14, and transmits the rotation of the motor shaft 14 to the rotary shaft 15. As shown in FIGS. 5 and 8, a motor shaft spline section 14A with spline grooves is formed on the outer circumferential surface of the motor shaft 14, and the motor shaft spline section 14A meshes with a motor shaft side hole spline section 39 of a coupling 38, which will be described later. A bottomed stopper mounting hole 14C is formed in the protruding end 14B of the motor shaft 14, and a bolt hole (internal thread hole) 14D is formed in the center of the bottom of the stopper mounting hole 14C.

[0023] The rotating shaft 15 is provided on the inner peripheral side of the spindle 12, extending in the axial direction. The rotating shaft 15 is formed using a single long rod-shaped body. A rotating shaft spline portion 15A is formed on the outer peripheral surface of one end side (electric motor 13 side) of the rotating shaft 15, and the rotating shaft spline portion 15A meshes with a rotating shaft side hole spline portion 40 of a coupling 38 (described later). In this manner, the rotating shaft 15 is coupled to the motor shaft 14 of the electric motor 13 via the coupling 38 and is rotationally driven by the electric motor 13. The other end side of the rotating shaft 15 protrudes from the open end of the small-diameter cylindrical portion 12C of the spindle 12, and a sun gear 23 (described later) is attached to the other end (protruding end) of the rotating shaft 15. An axially intermediate portion of the rotating shaft 15 is rotatably supported by a bearing 16 attached to an inner protrusion 12G of the spindle 12.

[0024] The wheel mounting sleeve 17 is rotatably mounted via two roller bearings 18 on the outer periphery of the small diameter cylindrical portion 12C that constitutes the spindle 12. The wheel mounting sleeve 17 is supported by the two roller bearings 18 and has a hollow cylindrical portion 17A that extends axially around the outer periphery of the small diameter cylindrical portion 12C, and an extended cylindrical portion 17B that protrudes axially from the tip of the hollow cylindrical portion 17A and extends in a direction away from the spindle 12. A cylindrical rim 7B that constitutes the rear wheel 7 is detachably mounted on the outer periphery of the wheel mounting sleeve 17, and the rear wheel 7 rotates integrally with the wheel mounting sleeve 17. An internal gear 32 (described below) and an outer drum 19 are fixed integrally to the end of the extended cylindrical portion 17B of the wheel mounting sleeve 17 using long bolts 20. The outer drum 19 is made of a cylindrical body and is provided with a flange portion 19A on one axial side. The outer drum 19 is fixed to the wheel mounting case 17 via an internal gear 32, and the other axial end thereof is an open end.

[0025] The reduction mechanism 21 is provided between the rotating shaft 15 and the wheel mounting case 17. The reduction mechanism 21 is made up of a first-stage planetary gear reduction mechanism 22 and a second-stage planetary gear reduction mechanism 29, and transmits the rotation of the rotating shaft 15 to the wheel mounting case 17 after reducing the speed in two stages.

[0026] The first-stage planetary gear reduction mechanism 22 includes a sun gear 23, multiple planet gears 24, and a carrier 26. The sun gear 23 is splined to the tip of the rotary shaft 15 that protrudes from the spindle 12 (small-diameter cylindrical portion 12C). The multiple planet gears 24 mesh with the sun gear 23 and a ring-shaped internal gear 25, and revolve around the sun gear 23 while rotating on their own axes. The carrier 26 is fixed via bolts or the like to the open end of the outer drum 19 that is integrated with the wheel mounting case 17, and rotatably supports the planet gears 24 via support pins 27.

[0027] Here, the internal gear 25 is formed using a ring gear and surrounds the sun gear 23 and the plurality of planetary gears 24 from the radial outside. The internal gear 25 is arranged to be rotatable relative to the inner circumferential surface of the outer drum 19 via a radial gap. The rotation of the internal gear 25 is transmitted to a second-stage planetary gear reduction mechanism 29 via a coupling 28.

[0028] The coupling 28 is provided between the first-stage planetary gear reduction mechanism 22 and the second-stage planetary gear reduction mechanism 29. The coupling 28 is formed in a disk shape with a boss 28A in the center. The outer periphery of the coupling 28 is spline-connected to the first-stage internal gear 25, and the inner periphery of the boss 28A of the coupling 28 is spline-connected to the second-stage sun gear 30. The coupling 28 transmits the rotation of the first-stage internal gear 25 to the second-stage sun gear 30, causing the sun gear 30 to rotate integrally with the first-stage internal gear 25.

[0029] The first-stage planetary gear reduction mechanism 22 converts the rotation of the sun gear 23 into rotational motion and revolutional motion of the multiple planetary gears 24 as the sun gear 23 rotates integrally with the rotary shaft 15 due to the electric motor 13. The rotational motion of the planetary gears 24 is transmitted to the internal gear 25 as reduced rotation, and the rotation of the internal gear 25 is transmitted to the second-stage planetary gear reduction mechanism 29 via a coupling 28. Meanwhile, the revolutional motion of the planetary gears 24 becomes rotation of the carrier 26 and is transmitted to the wheel mounting case 17 via the outer drum 19. At this time, because the wheel mounting case 17 rotates integrally with the second-stage internal gear 32, the revolution of the planetary gears 24 is suppressed to rotation synchronized with the wheel mounting case 17.

[0030] The second-stage planetary gear reduction mechanism 29 includes a cylindrical sun gear 30, multiple planet gears 31, and a carrier 33. The sun gear 30 is splined to the inner periphery of the boss 28A of the coupling 28 and rotates integrally with the coupling 28. The multiple planet gears 31 mesh with the sun gear 30 and a ring-shaped internal gear 32 and revolve around the sun gear 30 while rotating on their own axes. The carrier 33 rotatably supports the planet gears 31 via support pins 34. A cylindrical protrusion 33A is provided at the center of the carrier 33, and the outer periphery of the cylindrical protrusion 33A is splined to the inner periphery of the small-diameter cylindrical portion 12C. Here, the second-stage internal gear 32 is formed using a ring gear that radially surrounds the sun gear 30, multiple planet gears 31, etc. The internal gear 32 is integrally fixed between the extended cylindrical portion 17B of the wheel mounting case 17 and the outer drum 19 using a long bolt 20.

[0031] In the second-stage planetary gear reduction mechanism 29, the cylindrical protrusion 33A of the carrier 33 is splined to the small-diameter cylindrical portion 12C of the spindle 12. This restricts the revolution of the planetary gears 31 (the rotation of the carrier 33). Therefore, the second-stage planetary gear reduction mechanism 29 converts the rotation of the sun gear 30 into the rotation of the planetary gears 31 as the sun gear 30 rotates integrally with the coupling 28, and transmits this rotation of the planetary gears 31 to the second-stage internal gear 32. This causes the internal gear 32 to rotate at a reduced speed, and a large-output rotational torque that has been reduced in two stages by the first-stage planetary gear reduction mechanism 22 and the second-stage planetary gear reduction mechanism 29 is transmitted to the wheel mounting case 17 to which the internal gear 32 is fixed.

[0032] Here, lubricating oil L is stored inside the wheel mounting case 17, and the liquid level of the lubricating oil L is located lower than, for example, the bottommost part of the small-diameter cylindrical portion 12C that constitutes the spindle 12. Therefore, the lower part of the roller bearing 18 is immersed in the lubricating oil L, and a portion of the planetary gear reduction mechanisms 22, 29 is constantly lubricated by the lubricating oil L. Furthermore, the lubricating oil L splashed up by the planetary gear reduction mechanisms 22, 29 becomes a mist and is scattered inside the spindle 12, and is also supplied to the bearing 16 that supports the rotating shaft 15. As a result, when the traveling device 11 is operating, resistance due to agitation of the lubricating oil L is reduced, which suppresses energy loss and also suppresses heat generation by the traveling device 11.

[0033] The wet brake 35 is attached to the flange portion 12F of the spindle 12. The wet brake 35 is configured as a wet multi-plate hydraulic brake, and applies a braking force to a brake hub 36 attached to the wheel mounting case 17. This applies a braking force to the rotation of the wheel mounting case 17, i.e., the rotation of the rear wheel 7.

[0034] The partition wall 37 is provided inside the spindle 12. The partition wall 37 is formed from an annular plate, and the outer periphery of the partition wall 37 is attached using bolts or the like to the boundary between the tapered portion 12A and the intermediate cylindrical portion 12B of the spindle 12. The partition wall 37 divides the inside of the spindle 12 into a motor accommodating space 37A that accommodates the electric motor 13, and a cylindrical space 37B that communicates with the inside of the wheel mounting case 17.

[0035] The coupling 38 is disposed at the center of the annular partition wall 37 and couples the motor shaft 14 and the rotary shaft 15 of the electric motor 13. As shown in FIGS. 5 to 8, the coupling 38 is formed in an overall cylindrical shape. A motor shaft-side splined portion 39 with spline grooves is formed on the inner peripheral surface of one axial side (the motor shaft 14 side) of the coupling 38. The motor shaft-side splined portion 39 is spline-coupled to the motor shaft splined portion 14A of the motor shaft 14. As shown in FIG. 7, the tooth root diameter D1 of the motor shaft-side splined portion 39 is set larger than the tooth tip diameter D2 of the motor shaft splined portion 14A (D1 > D2). Therefore, a gap 38A is formed between the tooth roots of the multiple teeth that make up the motor shaft-side splined portion 39 and the tooth tips of the multiple teeth that make up the motor shaft splined portion 14A. This gap 38A is formed over the entire length of a spline coupling portion 39A where the motor shaft spline portion 14A and the motor shaft side hole spline portion 39 mesh with each other.

[0036] A rotary shaft side splined hole portion 40 having spline grooves is formed on the inner peripheral surface of the other axial side (rotary shaft 15 side) of the coupling 38. The rotary shaft side splined hole portion 40 is spline-coupled to the rotary shaft splined hole portion 15A of the rotary shaft 15. The tooth root circle diameter of the rotary shaft side splined hole portion 40 is set larger than the tooth tip circle diameter of the rotary shaft splined hole portion 15A. A gap (not shown) is formed between the tooth roots of the multiple teeth that make up the rotary shaft side splined hole portion 40 and the tooth tips of the multiple teeth that make up the rotary shaft splined hole portion 15A. This gap is formed over the entire length of the spline coupling portion 40A where the rotary shaft splined hole portion 15A and the rotary shaft side splined hole portion 40 mesh.

[0037] A stopper fitting portion 41 is formed on the inner peripheral surface of the axially intermediate portion of the coupling 38, located between the motor shaft side hole spline portion 39 and the rotating shaft side hole spline portion 40. A portion of the stopper fitting portion 41 adjacent to the motor shaft side hole spline portion 39 forms an annular oil passage 41A having a larger inner diameter than the stopper fitting portion 41. A coupling oil passage 43, which will be described later, opens into this annular oil passage 41A.

[0038] A sleeve fitting portion 38B is provided on one axial end face of the coupling 38. A sleeve 45, which will be described later, is fitted into the sleeve fitting portion 38B. An annular groove 38C is formed around the entire periphery of the inner circumferential surface of the coupling 38, on which the motor shaft side hole spline portion 39 is formed. A C-shaped hole retaining ring 42 is attached to the annular groove 38C. As shown in FIG. 7 , the outer diameter of the hole retaining ring 42 attached to the annular groove 38C is set smaller than the tooth tip circle diameter D2 of the motor shaft spline portion 14A splined to the motor shaft side hole spline portion 39. Therefore, the hole retaining ring 42 does not block the gap 38A formed between the tooth bottom of the motor shaft side hole spline portion 39 and the tooth tip of the motor shaft spline portion 14A.

[0039] The coupling oil passage 43 is provided in the axial middle of the coupling 38. The coupling oil passage 43 supplies lubricating oil L to a splined connection 39A between the motor shaft 14 (motor shaft splined portion 14A) and the coupling 38 (motor shaft side bore splined portion 39) and a splined connection 40A between the rotating shaft 15 (rotating shaft splined portion 15A) and the coupling 38 (rotating shaft side bore splined portion 40). The coupling oil passage 43 is formed by multiple oil passages extending radially at equal angular intervals from the center of the coupling 38. The coupling oil passage 43 extends from the annular oil passage 41A of the stopper fitting portion 41 to the outer circumferential surface of the coupling 38. This allows the coupling oil passage 43 to open (communicate) with an oil reservoir 50 (described later). The portion of the coupling oil passage 43 that opens into the oil reservoir 50 is a tapered large-diameter opening end 43A having a diameter larger than that of the coupling oil passage 43 (see FIG. 10).

[0040] The stopper 44 is detachably attached to the protruding end 14B of the motor shaft 14 using a stopper bolt 44A. As shown in FIG. 8 , the stopper 44 is formed as a stepped cylinder overall and has a small-diameter fitting portion 44B and a large-diameter fitting portion 44C. The small-diameter fitting portion 44B fits into the stopper mounting hole 14C of the motor shaft 14. The large-diameter fitting portion 44C has a larger outer diameter than the small-diameter fitting portion 44B and fits into the addendum circle of the motor-shaft-side hole spline portion 39 of the coupling 38. The stopper 44 radially positions the coupling 38 with respect to the motor shaft 14 by fitting the large-diameter fitting portion 44C into the addendum circle of the motor-shaft-side hole spline portion 39. The boundary between the small diameter fitting portion 44B and the large diameter fitting portion 44C forms an annular step portion 44D, which faces the protruding end 14B of the motor shaft 14 in the axial direction.

[0041] A bolt insertion hole 44E is formed in the center of the small-diameter fitting portion 44B, penetrating in the axial direction. A bottomed countersunk hole 44F is formed in the large-diameter fitting portion 44C, concentric with the bolt insertion hole 44E. The stopper 44 is fitted with the small-diameter fitting portion 44B in the stopper mounting hole 14C of the motor shaft 14, and the hole retaining ring 42 is sandwiched between the annular step portion 44D and the protruding end 14B of the motor shaft 14. In this state, the stopper bolt 44A inserted through the bolt insertion hole 44E is screwed into the bolt hole 14D of the motor shaft 14. This attaches the stopper 44 to the motor shaft 14, with the head of the stopper bolt 44A housed in the countersunk hole 44F.

[0042] The stopper 44 is also formed with a plurality of stopper oil passages 44G that extend from the counterbore 44F through to the outer circumferential surface of the large-diameter fitting portion 44C. The stopper oil passages 44G consist of a plurality of oil passages that extend radially at equal angular intervals from the center of the stopper 44. When the motor-shaft-side splined hole portion 39 of the coupling 38 is spline-coupled to the motor-shaft splined portion 14A of the motor shaft 14, the stopper oil passages 44G communicate with the coupling oil passage 43 via the annular oil passage 41A of the stopper fitting portion 41 provided in the coupling 38. As a result, as shown in FIG. 5, lubricating oil L supplied to the coupling oil passage 43 of the coupling 38 flows to the annular oil passage 41A of the coupling 38, the stopper oil passage 44G of the stopper 44, and the counterbore 44F. The lubricating oil L is then distributed to a splined joint 39A between the motor shaft side hole splined portion 39 and the motor shaft splined portion 14A, and to a splined joint 40A between the rotating shaft side hole splined portion 40 and the rotating shaft splined portion 15A.

[0043] The sleeve 45 is provided between one axial side of the coupling 38 and the motor shaft 14. The sleeve 45 is formed in a stepped cylindrical shape having a small-diameter cylindrical portion 45A and a large-diameter cylindrical portion 45B. The inner peripheral side of the sleeve 45 is fitted onto the motor shaft 14, and the outer peripheral side of the small-diameter cylindrical portion 45A is fitted into the sleeve fitting portion 38B of the coupling 38. The sleeve 45 radially positions one axial side of the coupling 38 with respect to the motor shaft 14.

[0044] Next, the coupling housing 46 used in this embodiment will be described with reference to FIGS.

[0045] The coupling housing 46 is attached to the electric motor 13 so as to surround the outer periphery of the coupling 38. The coupling housing 46 has a cylindrical portion 46A that surrounds the outer periphery of the coupling 38, and a flange portion 46B that expands in diameter from one axial side (the electric motor 13 side) of the cylindrical portion 46A. The flange portion 46B is attached to the electric motor 13 using bolts 46C. Meanwhile, a coupling fitting portion 46D is provided on the other axial side of the cylindrical portion 46A. The inner circumferential surface of the coupling fitting portion 46D slidably fits onto the outer circumferential surface of the coupling 38, preventing misalignment of the coupling 38. In addition, an oil reservoir 50, which will be described later, is formed on the inner circumferential surface of the coupling fitting portion 46D.

[0046] The cylindrical portion 46A of the coupling housing 46 is formed with a housing oil passage 47 located above the coupling 38 and a discharge oil passage 48 located below the coupling 38. The housing oil passage 47 branches a portion of the lubricating oil L flowing through the lubricating oil circulation circuit 51 and guides it to the coupling oil passage 43 of the coupling 38. One end 47A of the housing oil passage 47 opens to the outer peripheral surface of the cylindrical portion 46A and is connected to a coupling lubrication pipe 59, which will be described later. Meanwhile, the other end 47B of the housing oil passage 47 is connected to an oil reservoir 50 formed on the inner peripheral surface of the coupling fitting portion 46D and communicates with the coupling oil passage 43 via the oil reservoir 50. Two seal rings 49 are provided on the inner peripheral surface of the coupling fitting portion 46D, sandwiching the oil reservoir 50 in the axial direction. The inner peripheral edges of these two seal rings 49 slide against the outer peripheral surface of the coupling 38, thereby sealing between the coupling fitting portion 46D and the coupling 38.

[0047] The oil reservoir 50 is formed on the inner peripheral surface of the coupling fitting portion 46D that constitutes the coupling housing 46. The oil reservoir 50 covers the outer peripheral side of the coupling 38 and is in communication with the housing oil passage 47 and the coupling oil passage 43. The oil reservoir 50 is formed as a circular groove with an inner diameter larger than that of the coupling fitting portion 46D and is disposed between two seal rings 49. The oil reservoir 50 is eccentric to the radially upper side (toward the housing oil passage 47) with respect to the center of the coupling fitting portion 46D, i.e., the rotation center of the coupling 38. The upper end side of the oil reservoir 50 is in communication with the other end 47B of the housing oil passage 47 (see FIG. 9).

[0048] The oil reservoir 50 is radially eccentric with respect to the center of the coupling fitting portion 46D (the center of rotation of the coupling 38). This configuration allows the volume of the portion of the oil reservoir 50 located radially above the coupling housing 46 to be greater than the volume of the portion located radially below. Specifically, the oil reservoir 50 includes a wide oil reservoir 50A located above the coupling 38 and spaced farther from the outer circumferential surface of the coupling 38, and a narrow oil reservoir 50B located below the coupling 38 and spaced farther from the outer circumferential surface of the coupling 38. The lubricating oil L stored in the wide oil reservoir 50A flows smoothly downward due to its own weight and enters the inner circumferential side of the coupling 38 through the coupling oil passage 43. This allows the lubricating oil L to be smoothly supplied to the splined connection 39A between the motor shaft 14 and the coupling 38 and the splined connection 40A between the rotating shaft 15 and the coupling 38.

[0049] When coupling the motor shaft 14 and the rotating shaft 15 using the coupling 38, the large-diameter fitting portion 44C of the stopper 44 is fitted into the stopper fitting portion 41 of the coupling 38. Meanwhile, the hole retaining ring 42 is attached to the annular groove 38C of the coupling 38, and the hole retaining ring 42 is brought into contact with the annular step portion 44D of the stopper 44. This positions the stopper 44 in the axial direction of the coupling 38.

[0050] Next, the motor shaft side hole spline portion 39 of the coupling 38 is splined to the motor shaft spline portion 14A of the motor shaft 14. Then, with the hole retaining ring 42 abutting against the protruding end 14B of the motor shaft 14, the stopper bolt 44A is screwed into the bolt hole 14D of the motor shaft 14. In this way, the rotating shaft spline portion 15A of the rotating shaft 15 is splined to the rotating shaft side hole spline portion 40 of the coupling 38 attached to the motor shaft 14, and the rotating shaft 15 is inserted in the axial direction. As a result, the motor shaft 14 and the rotating shaft 15 can be coupled using the coupling 38, as shown in FIG. 5.

[0051] In this state, the coupling oil passage 43 of the coupling 38 communicates with the oil reservoir 50 of the coupling housing 46. The stopper oil passage 44G of the stopper 44 communicates with the annular oil passage 41A of the stopper fitting portion 41 provided in the coupling 38. Meanwhile, as shown in FIG. 7, a gap 38A is formed between the tooth bottom of the motor shaft side hole spline portion 39 formed in the coupling 38 and the tooth tip of the motor shaft spline portion 14A. Similarly, a gap (not shown) is also formed between the tooth bottom of the rotary shaft side hole spline portion 40 formed in the coupling 38 and the tooth tip of the rotary shaft spline portion 15A.

[0052] The lubricating oil circulation circuit 51 is provided inside the spindle 12 and the axle housing 10. The main circuit of the lubricating oil circulation circuit 51 is made up of a suction pipe 52, a lubricating oil pump 53, a discharge pipe 55, a supply pipe 56, etc. The lubricating oil circulation circuit 51 repeatedly supplies lubricating oil L stored inside the wheel mounting case 17 to the reduction gear mechanism 21, roller bearing 18, bearing 16, etc. The lubricating oil circulation circuit 51 also has a joint lubrication circuit 58, which will be described later.

[0053] The suction pipe 52 is provided inside the spindle 12 and the axle housing 10. One longitudinal side of the suction pipe 52 is connected to the suction port of the lubricating oil pump 53. The other longitudinal side of the suction pipe 52 is disposed below the rotating shaft 15 and extends in the axial direction of the spindle 12. A tip 52A of the suction pipe 52 is inserted into a radial hole 12H of the spindle 12 and is immersed in the lubricating oil L inside the wheel mounting case 17. The lubricating oil pump 53 sucks up the lubricating oil L through the suction pipe 52.

[0054] The branch joint 54 is attached to the motor mounting seat 12E provided on the spindle 12. The branch joint 54 has, for example, one inlet and two outlets (neither of which is shown) with different flow rates. A discharge pipe 55 connects the discharge port of the lubricating oil pump 53 to the inlet of the branch joint 54. The lubricating oil L discharged from the lubricating oil pump 53 flows into the branch joint 54 through the discharge pipe 55 and is branched into two paths by a supply pipe 56 connected to the two outlets of the branch joint 54 and a coupling lubrication pipe 59, which will be described later. An oil cooler 57 is provided midway along the discharge pipe 55.

[0055] The supply pipe 56 is provided inside the spindle 12. One end of the supply pipe 56 is connected to the outlet with the larger flow rate out of the two outlets of the branch joint 54. The other longitudinal end of the supply pipe 56 is disposed above the rotating shaft 15 and extends in the axial direction of the spindle 12. A tip 56A of the supply pipe 56 extends along the rotating shaft 15 into the cylindrical protruding portion 33A of the second-stage carrier 33. As a result, most of the lubricating oil L discharged from the lubricating oil pump 53 is cooled by the oil cooler 57 and supplied to the rotating shaft 15 through the tip 56A of the supply pipe 56. This lubricating oil L not only cools the rotating shaft 15 but also splashes from the rotating shaft 15 to lubricate the bearings 16 and the like.

[0056] The joint lubrication circuit 58 branches off a portion of the lubricating oil L supplied to the reduction gear mechanism 21, etc., and supplies it to the joint (spline joint 39A) between the motor shaft 14 and the coupling 38, and the joint (spline joint 40A) between the rotating shaft 15 and the coupling 38. The joint lubrication circuit 58 is made up of a coupling lubrication pipe 59, the housing oil passage 47 and oil reservoir 50 of the coupling housing 46, the coupling oil passage 43 of the coupling 38, the stopper oil passage 44G and countersunk hole 44F of the stopper 44, etc.

[0057] The coupling lubrication pipe 59 is provided inside the spindle 12 together with the supply pipe 56. One end of the coupling lubrication pipe 59 is connected to the outlet with the smaller flow rate out of the two outlets of the branch joint 54. The other end 59A of the coupling lubrication pipe 59 is connected to one end 47A of a housing oil passage 47 formed in the coupling housing 46. As a result, a portion of the lubricating oil L discharged from the lubricating oil pump 53 is introduced from the coupling lubrication pipe 59, which constitutes the joint lubrication circuit 58, through the housing oil passage 47 of the coupling housing 46 and into the coupling oil passage 43 of the coupling 38.

[0058] Lubricating oil L introduced into coupling oil passage 43 branches into a path indicated by arrow F1 and a path indicated by arrow F2 in Figure 5. Lubricating oil L flowing through the path indicated by arrow F1 is supplied from coupling oil passage 43 to motor shaft side splined portion 39 through annular oil passage 41A in stopper fitting portion 41. In this case, a gap 38A is formed between the tooth bottom of motor shaft side splined portion 39 and the tooth tip of motor shaft splined portion 14A. As a result, lubricating oil L flows in the axial direction of motor shaft side splined portion 39 through gap 38A and lubricates splined connection portion 39A between motor shaft side splined portion 39 and motor shaft splined portion 14A.

[0059] On the other hand, the lubricating oil L flowing through the path indicated by arrow F2 is supplied from the coupling oil passage 43 through the stopper oil passage 44G of the stopper 44 and the counterbore 44F to the rotary shaft side splined portion 40. In this case, a gap (not shown) is formed between the tooth bottom of the rotary shaft side splined portion 40 and the tooth tip of the rotary shaft splined portion 15A. This allows the lubricating oil L to flow in the axial direction of the rotary shaft side splined portion 40 through the gap and lubricate the splined coupling portion 40A between the rotary shaft side splined portion 40 and the rotary shaft splined portion 15A.

[0060] The traveling device 11 of the dump truck 1 according to this embodiment has the configuration described above, and its operation will now be described.

[0061] When the driver in the cab 5 of the dump truck 1 starts the engine 8, the hydraulic pump is driven to rotate and the generator (neither of which is shown) generates electricity. When the dump truck 1 is driven to travel, power is supplied from the generator to the electric motor 13, which operates the electric motor 13 and rotates the rotary shaft 15.

[0062] The rotation of the rotating shaft 15 is reduced in two stages by the first-stage planetary gear reduction mechanism 22 and the second-stage planetary gear reduction mechanism 29 that make up the reduction mechanism 21, and is then transmitted to the wheel mounting case 17, and the wheel mounting case 17 rotates with a large rotational torque. As a result, the left and right rear wheels 7, which serve as drive wheels, rotate integrally with the wheel mounting case 17, enabling the dump truck 1 to travel and drive.

[0063] When the traveling device 11 is in operation, the lubricating oil L stored in the wheel mounting case 17 is scooped up by the planetary gears 24, 31 and the like that make up the planetary gear reduction mechanisms 22, 29, and is supplied to the meshing portions between the gears, the roller bearing 18, the bearing 16, etc. The lubricating oil L then drips downward and is collected at the bottom of the wheel mounting case 17.

[0064] The lubricating oil L collected at the lower side of the wheel mounting case 17 is sucked up from the tip 52A of the suction pipe 52 by the lubricating oil pump 53 and discharged into the discharge pipe 55. The lubricating oil L discharged into the discharge pipe 55 is cooled in an oil cooler 57 and then flows into the branch joint 54. Most of the lubricating oil L that flows into the branch joint 54 is guided to the supply pipe 56 and supplied to the rotating shaft 15 through the tip 56A of the supply pipe 56. In this way, the rotating shaft 15 can be cooled by the lubricating oil L, and the bearings 16 and the like can be lubricated by the lubricating oil L that splashes from the rotating shaft 15.

[0065] The lubricating oil L introduced from the branch joint 54 to the coupling lubrication pipe 59 flows into the oil reservoir 50 through the housing oil passage 47 of the coupling housing 46. After being temporarily stored in the oil reservoir 50, the lubricating oil L is introduced into the annular oil passage 41A from the coupling oil passage 43 of the coupling 38. The lubricating oil L introduced into the annular oil passage 41A is divided into the path indicated by the arrow F1 and the path indicated by the arrow F2 in FIG.

[0066] Lubricating oil L flowing along the path indicated by arrow F1 is supplied from coupling oil passage 43 through annular oil passage 41A to motor shaft side spline portion 39. A gap 38A is formed between the tooth bottom of motor shaft side spline portion 39 and the tooth tip of motor shaft spline portion 14A. This allows lubricating oil L to flow axially through gap 38A into motor shaft side spline portion 39 and lubricate the splined connection 39A between motor shaft side spline portion 39 and motor shaft spline portion 14A. The remaining lubricating oil L supplied to splined connection 39A between motor shaft side spline portion 39 and motor shaft spline portion 14A flows downward from the connection between coupling 38 (sleeve-fitting portion 38B) and sleeve 45 into coupling housing 46. This lubricating oil L is discharged to the outside of coupling housing 46 (into spindle 12) through discharge oil passage 48. This prevents the lubricating oil L from leaking to the electric motor 13 side, and the electric motor 13 can be protected.

[0067] On the other hand, the lubricating oil L flowing through the path indicated by arrow F2 is supplied to the rotary shaft side splined portion 40 from the coupling oil passage 43 through the annular oil passage 41A, the stopper oil passage 44G of the stopper 44, and the counterbore 44F. In this case, a gap (not shown) is formed between the tooth bottom of the rotary shaft side splined portion 40 and the tooth tip of the rotary shaft splined portion 15A. This allows the lubricating oil L to flow in the axial direction of the rotary shaft side splined portion 40 through the gap, and the splined connection portion 40A between the rotary shaft side splined portion 40 and the rotary shaft splined portion 15A can be lubricated by the lubricating oil L. The remainder of the lubricating oil L supplied to the splined connection portion 40A between the rotary shaft side splined portion 40 and the rotary shaft splined portion 15A is discharged from the rotary shaft splined portion 15A to the outer peripheral surface of the rotary shaft 15. This lubricating oil L turns into mist as the rotary shaft 15 rotates and is scattered inside the spindle 12 , lubricating the bearings 16 that support the rotary shaft 15 .

[0068] When the electric motor 13 rotates the coupling 38 at high speed, a large centrifugal force acts on the coupling 38, hindering the flow of the lubricating oil L introduced into the annular oil passage 41A through the coupling oil passage 43. This may result in a decrease in lubrication at the spline connection portion 39A between the motor shaft 14 and the coupling 38, and at the spline connection portion 40A between the rotating shaft 15 and the coupling 38.

[0069] In contrast, in the traveling device 11 according to this embodiment, an oil reservoir 50 that communicates with the housing oil passage 47 and the coupling oil passage 43 and temporarily stores the lubricating oil L is formed in the coupling fitting portion 46D of the coupling housing 46. The oil reservoir 50 is eccentric upward with respect to the center of the coupling fitting portion 46D, and thus has a wide oil reservoir 50A that is spaced farther from the outer peripheral surface of the coupling 38, and a narrow oil reservoir 50B that is spaced farther from the outer peripheral surface of the coupling 38. The capacity of the wide oil reservoir 50A, which is located on the radially upper side of the coupling housing 46, is greater than the capacity of the narrow oil reservoir 50B, which is located on the radially lower side.

[0070] For this reason, the lubricating oil L stored in the wide oil reservoir 50A flows smoothly downward through the coupling oil passage 43 due to its own weight. Therefore, even when a large centrifugal force acts on the coupling 38 during high-speed rotation, the lubricating oil L is smoothly introduced into the annular oil passage 41A through the coupling oil passage 43. As a result, even when the coupling 38 rotates at high speed, sufficient lubricating oil L can be supplied to the splined connection portion 39A between the motor shaft 14 and the coupling 38 and the splined connection portion 40A between the rotating shaft 15 and the coupling 38, thereby improving lubrication.

[0071] Furthermore, the portion of the coupling oil passage 43 that opens into the oil reservoir 50 is a tapered large-diameter opening end 43A that has a larger diameter than the coupling oil passage 43. This allows the lubricating oil L stored in the oil reservoir 50 to be guided more smoothly to the coupling oil passage 43. Therefore, a large amount of lubricating oil L can be supplied from the coupling oil passage 43 through the annular oil passage 41A and the like to the splined connection portion 39A between the motor shaft 14 and the coupling 38 and the splined connection portion 40A between the rotating shaft 15 and the coupling 38.

[0072] Thus, in this embodiment, the present invention includes an electric motor 13 provided on the body of a work vehicle having wheels, a motor shaft 14 that outputs the rotation of the electric motor 13, a rotating shaft 15 to which the rotation of the motor shaft 14 is transmitted, a speed reduction mechanism 21 that reduces the rotation of the rotating shaft 15 and transmits it to the wheels, a lubricating oil circulation circuit 51 for supplying lubricating oil L to the speed reduction mechanism 21, a cylindrical coupling 38 that connects the motor shaft 14 and the rotating shaft 15, a coupling housing 46 that is provided on the electric motor 13 and has a fitting portion that slidably fits on the outer peripheral surface of the coupling 38, and a coupling oil separator that is provided on the coupling 38 and supplies lubricating oil L to a splined connection portion 39A between the motor shaft 14 and the coupling 38 and a splined connection portion 40A between the rotating shaft 15 and the coupling 38. In the travelling device 11 of the work vehicle, the travelling device 11 is provided with a passage 43, and a housing oil passage 47 provided in the coupling housing 46, which branches off a portion of the lubricating oil L flowing in the lubricating oil circulation circuit 51 and leads it to the coupling oil passage 43. The coupling housing 46 is provided with an oil reservoir 50 which is connected to the housing oil passage 47 and the coupling oil passage 43 while covering the outer periphery of the coupling 38, and which stores the lubricating oil L to be supplied to the spline connection portion 39A between the motor shaft 14 and the coupling 38, and the spline connection portion 40A between the rotating shaft 15 and the coupling 38 through the coupling oil passage 43, and the oil reservoir 50 has a shape in which the capacity of the portion located radially upper of the coupling housing 46 is larger than the capacity of the portion located radially lower.

[0073] With this configuration, the lubricating oil L stored in the portion of the oil reservoir 50 of the coupling housing 46 that has a shape that increases the capacity flows smoothly downward due to its own weight. As a result, even when a large centrifugal force acts on the coupling 38 during high-speed rotation, the lubricating oil L is smoothly introduced into the annular oil passage 41A through the coupling oil passage 43. As a result, even during high-speed rotation of the coupling 38, sufficient lubricating oil L can be supplied to the splined connection 39A between the motor shaft 14 and the coupling 38 and the splined connection 40A between the rotating shaft 15 and the coupling 38, and these splined connection portions 39A, 40A can be properly lubricated.

[0074] In this embodiment, the oil reservoir 50 is formed in a circular shape that is eccentric radially upward with respect to the rotation center of the coupling 38. With this configuration, the capacity of the portion of the oil reservoir 50 that is eccentric with respect to the rotation center of the coupling 38 can be increased.

[0075] In this embodiment, the oil reservoir 50 has a wide oil reservoir 50A that is spaced farther from the outer peripheral surface of the coupling 38, and a narrow oil reservoir 50B that is spaced farther from the outer peripheral surface of the coupling 38, and the wide oil reservoir 50A is disposed radially above the coupling housing 46. With this configuration, even when the coupling 38 is rotating at high speed, the lubricating oil L stored in the wide oil reservoir 50A can smoothly flow into the coupling oil passage 43 due to its own weight.

[0076] In the embodiment, a large-diameter opening end 43A is formed in the portion of the coupling oil passage 43 that opens into the oil reservoir 50, the large-diameter opening end 43A being larger than the diameter of the coupling oil passage 43. With this configuration, the lubricating oil L stored in the oil reservoir 50 can be more smoothly guided to the coupling oil passage 43, and a large amount of lubricating oil L can be supplied to the spline connection portion 39A between the motor shaft 14 and the coupling 38, and the spline connection portion 40A between the rotating shaft 15 and the coupling 38.

[0077] In the embodiment, the oil reservoir 50 provided in the coupling housing 46 is formed in a circular shape that is eccentric radially upward with respect to the center of the coupling fitting portion 46D (the rotation center of the coupling 38). This oil reservoir 50 is exemplified as including a wide oil reservoir 50A that is spaced widely from the outer peripheral surface of the coupling 38, and a narrow oil reservoir 50B that is spaced narrowly from the outer peripheral surface of the coupling 38. However, the present invention is not limited to this, and an oil reservoir 60 such as a first modified example shown in FIG. 11 may also be used.

[0078] The oil reservoir 60 according to the first modification is provided in the coupling housing 46'. The oil reservoir 60 is formed in a gourd shape overall, with a circular portion 60A arranged concentrically with the center of the coupling fitting portion 46D (the rotation center of the coupling 38) and a semicircular portion 60B arranged radially upward of the coupling housing 46. The upper end side of the semicircular portion 60B communicates with the other end 47B of the housing oil passage 47. This increases the capacity of the portion of the oil reservoir 60 (semicircular portion 60B) located radially upward of the coupling housing 46'. Therefore, the oil reservoir 60 according to the first modification can also achieve the same effects as the oil reservoir 50 according to the embodiment.

[0079] Also, in the embodiment, a tapered large-diameter opening end 43A having a diameter larger than that of the coupling oil passage 43 is formed at a portion of the coupling oil passage 43 provided in the coupling 38 that opens into the oil reservoir 50. However, the present invention is not limited to this, and for example, as in a second modified example shown in FIG. 12 , a countersunk large-diameter opening end 43A′ may be formed that has a diameter (hole diameter) larger than that of the coupling oil passage 43 and is made of a bottomed hole that is arranged concentrically with the coupling oil passage 43.

[0080] Furthermore, in the embodiment, the description has been given taking the rear-wheel drive dump truck 1 as an example, but the present invention is not limited to this and may be applied to, for example, a front-wheel drive dump truck or a four-wheel drive dump truck in which both the front and rear wheels are driven. [Explanation of symbols]

[0081] 1 dump truck 2. Body 7 Rear wheel (wheel) 11 Running gear 13 Electric motor 14 Motor shaft 15 Rotation axis 15A Rotating shaft spline part 21 Reduction mechanism 38 Coupling 39 Motor shaft side hole spline part 39A, 40A spline joint 40 Rotating shaft side hole spline part 43 Coupling oil passage 43A, 43A' Large diameter opening end 46,46′ Coupling housing 47 Housing oil passage 50,60 Oil reservoir 50A wide oil reservoir 50B Narrow oil reservoir 51 Lubricating oil circulation circuit

Claims

1. a motor provided on a body of a work vehicle having wheels; a motor shaft that outputs rotation of the motor; a rotating shaft to which the rotation of the motor shaft is transmitted; a speed reduction mechanism that reduces the rotation speed of the rotary shaft and transmits the reduced rotation speed to the wheels; a lubricating oil circulation circuit for supplying lubricating oil to the reduction mechanism; a cylindrical coupling that couples the motor shaft and the rotary shaft; a coupling housing provided on the motor and having a fitting portion that slidably fits onto an outer peripheral surface of the coupling; a coupling oil passage provided in the coupling for supplying lubricating oil to a joint between the motor shaft and the coupling and a joint between the rotating shaft and the coupling; a housing oil passage provided in the coupling housing, which branches a portion of the lubricating oil flowing through the lubricating oil circulation circuit and leads it to the coupling oil passage, The coupling housing is provided with an oil reservoir portion that communicates with the housing oil passage and the coupling oil passage while covering the outer circumferential side of the coupling, and that stores lubricating oil to be supplied to the connection portion between the motor shaft and the coupling and the connection portion between the rotating shaft and the coupling through the coupling oil passage, A travel device for a work vehicle, characterized in that the oil reservoir has a shape such that the capacity of the portion located radially above the coupling housing is greater than the capacity of the portion located radially below the coupling housing.

2. 2. The travel device for a work vehicle according to claim 1, wherein the oil reservoir is formed in a circular shape that is eccentric to the radially upward direction relative to the center of rotation of the coupling.

3. the oil reservoir has a wide oil reservoir having a large gap between it and the outer peripheral surface of the coupling, and a narrow oil reservoir having a small gap between it and the outer peripheral surface of the coupling, 2. A travel device for a work vehicle according to claim 1, wherein the wide oil reservoir is disposed radially above the coupling housing.

4. 2. The travel device for a work vehicle according to claim 1, wherein a large-diameter opening end having a diameter larger than that of the coupling oil passage is formed at a portion of the coupling oil passage that opens into the oil reservoir.

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