Traveling device

Abstract

Properly lubricate the spline connection between the output shaft of the drive motor and the pinion gear. [Solution] The traveling device 11 comprises a casing 12, a traveling motor 22 mounted on the casing 12, a pinion gear 39 supported within the casing 12 via bearings 40, 41 and having a female spline 39D that fits onto a male spline 22B formed on the output shaft 22A of the traveling motor 22, planetary gear reduction mechanisms 29, 33 that reduce and output the rotation of the pinion gear 39, and a transmission gear 24 that transmits the rotation of the pinion gear 39 to the sun gear 30. Lubricating oil L is held inside the casing 12, and the axis B of the pinion gear 39 is positioned higher than the axis A of the sun gear 30. A notch 39G is provided on one axial end of the pinion gear 39 to guide the lubricating oil L supplied to the outer circumference of the pinion gear 39 to the female spline 39D.

Description

[Technical Field]

[0001] The present disclosure relates to a traveling device mounted on construction machinery such as a hydraulic excavator and a hydraulic crane. [Background Art]

[0002] In general, construction machinery such as hydraulic excavators and hydraulic cranes includes a self-propelled crawler-type lower traveling body and an upper rotating body pivotably provided on the lower traveling body, and a traveling device is mounted on the lower traveling body. The traveling device includes a casing attached to a track frame of the lower traveling body, a travel motor attached to the casing, and a speed reducer provided in the casing. The rotation of the travel motor is transmitted to driving wheels after being reduced in speed by the speed reducer, and the driving wheels rotate with high torque to orbit the crawler wound around the driving wheels and idlers. Thereby, the crawler-type lower traveling body can travel stably on a work site.

[0003] Here, as a speed reducer for a traveling device mounted on a lower traveling body of a hydraulic excavator or the like, a compact planetary gear speed reduction mechanism with a large reduction ratio is used. Normally, the axis (rotation center) of the travel motor (output shaft), the axis of a sun gear constituting the planetary gear speed reduction mechanism, and the axis of a driving wheel are arranged concentrically.

[0004] In contrast, in a traveling device of an ultra-large hydraulic excavator used for, for example, open-pit mining of minerals, in order to prevent the travel motor from coming into contact with rocks or the like protruding from the ground when the lower traveling body travels, the axis of the travel motor is arranged at a position higher than the axis of the sun gear constituting the planetary gear speed reduction mechanism. For this reason, in the traveling device of a large hydraulic excavator, a pinion gear is attached to an output shaft of the travel motor, and a transmission gear is arranged between the pinion gear and the sun gear of the planetary gear speed reduction mechanism. Thereby, the rotation of the travel motor is transmitted from the pinion gear to the sun gear of the planetary gear speed reduction mechanism via the transmission gear (Patent Document 1).

[0005] In this configuration, the planetary gear reduction mechanism and various bearings, which are located within the casing of the running gear, are immersed in the lubricating oil filled within the casing during operation, thus maintaining a adequately lubricated state. In contrast, the axis of the pinion gear, which is spline-coupled to the output shaft of the running motor, is positioned higher than the axis of the sun gear that constitutes the planetary gear reduction mechanism. As a result, the pinion gear and the bearings supporting it are not immersed in the lubricating oil held within the casing, and there is a risk that sufficient lubrication may not be supplied.

[0006] In contrast, Patent Document 1 sets the tooth width of the transmission gear that meshes with the pinion gear to be larger than the tooth width of the pinion gear. This allows a large amount of lubricating oil held in the casing to be splashed up by the tooth surface of the rotating transmission gear, thereby supplying sufficient lubricating oil to the bearing supporting the pinion gear. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2004-36840 [Overview of the project] [Problems that the invention aims to solve]

[0008] Incidentally, a female spline is formed on the inner circumference of the pinion gear, and this female spline is fitted (spline-coupled) to a male spline formed on the output shaft of the travel motor. The spline-coupled portion between the pinion gear and the output shaft wears down due to repeated contact between the tooth surfaces caused by vibrations during the operation of the travel device. For this reason, it is necessary to protect the female spline of the pinion gear and the male spline of the output shaft by supplying sufficient lubricant to the spline-coupled portion between the pinion gear and the output shaft.

[0009] In contrast, with the traveling device described in Patent Document 1, it is difficult to supply sufficient lubricating oil to the spline connection between the output shaft of the traveling motor and the pinion gear, and there is a risk that the female splines of the pinion gear and the male splines of the output shaft will wear out prematurely.

[0010] The object of the present invention is to provide a traveling device that enables proper lubrication of the spline connection between the output shaft of the traveling motor and the pinion gear. [Means for solving the problem]

[0011] The present invention relates to a travel device comprising: a travel motor mounted in a casing with an output shaft protruding into the casing; a male spline formed on the output shaft of the travel motor; a pinion gear rotatably supported within the casing via a bearing, having a female spline formed on its inner circumference that fits into the male spline and teeth formed on its outer circumference; a planetary gear reduction mechanism provided within the casing that reduces the rotation of the pinion gear and outputs the reduced rotation; and a transmission gear provided between the pinion gear and the planetary gear reduction mechanism that transmits the rotation of the pinion gear to the sun gear of the planetary gear reduction mechanism, wherein lubricating oil for lubricating the planetary gear reduction mechanism is held within the casing, and the axis of the pinion gear is positioned higher than the axis of the sun gear, characterized in that a notch is provided on one axial end of the pinion gear to guide the lubricating oil supplied to the outer circumference of the pinion gear to the female spline. [Effects of the Invention]

[0012] According to the present invention, lubricating oil supplied to the outer circumference of the pinion gear can be guided to the female spline through a notch provided on one axial end of the pinion gear, thereby properly lubricating the spline connection between the output shaft and the pinion gear. [Brief explanation of the drawing]

[0013] [Figure 1] This is a left side view showing a hydraulic excavator to which an embodiment of the present invention is applied. [Figure 2] This is a cross-sectional view of the hydraulic excavator's travel mechanism, taken from the direction of II-II in Figure 1. [Figure 3] This is a magnified cross-sectional view of the area around the output shaft and pinion gear in Figure 2. [Figure 4] This is a cross-sectional view showing the pinion gear with the output shaft removed, as shown in Figure 3. [Figure 5] This is a perspective view of the pinion gear, seen from one end in the axial direction where the notch is formed. [Figure 6] This is a perspective view of the pinion gear, seen from the other axial end where the oil groove is formed. [Figure 7] This is a cross-sectional view taken at the same position as in Figure 4, which shows the traveling device according to the second embodiment. [Figure 8] This is a perspective view showing a modified pinion gear. [Figure 9] This is a cross-sectional view taken at the same position as Figure 4, which shows a modified running gear. [Modes for carrying out the invention]

[0014] The following will describe in detail, with reference to Figures 1 to 9, an example of how the travel device according to an embodiment of the present invention is applied to the lower travel body of a super-large hydraulic excavator. In this embodiment, the travel direction of the hydraulic excavator will be described as the front-rear direction, and the direction perpendicular to the travel direction of the hydraulic excavator will be described as the left-right direction.

[0015] Figures 1 to 6 show a first embodiment of the present invention. In Figure 1, an extra-large hydraulic excavator 1 used for open-pit mining of minerals has a crawler-type lower traveling body 2 and an upper rotating body 3 that is rotatably mounted on the lower traveling body 2, and a working device 4 is provided on the front side of the upper rotating body 3.

[0016] The lower traveling body 2 comprises a track frame 6 having left and right side frames 5 extending in the front-rear direction (only the left side frame is illustrated), idler wheels 7 respectively disposed on the front end side of the left and right side frames 5, drive wheels 8 respectively disposed on the rear end side of the left and right side frames 5, and a crawler (track shoe) 9 wound around the idler wheel 7 and the drive wheel 8. A cylindrical mounting base 5A is fixed to the rear end side of the side frame 5, and a casing 12 of a traveling device 11 to be described later is mounted to the mounting base 5A (see FIG. 2).

[0017] The traveling device 11 is provided between the mounting base 5A of the side frame 5 and the drive wheel 8. The traveling device 11 decelerates the rotation of a travel motor 22 to be described later and transmits the decelerated rotation to the drive wheel 8, thereby rotating the drive wheel 8 with large torque and causing the hydraulic excavator 1 to travel. As shown in FIG. 2, the traveling device 11 comprises a casing 12, a travel motor 22, planetary gear reduction mechanisms 29, 33, a transmission gear 24, a transmission shaft 26, a rotating shaft 37, and a pinion gear 39.

[0018] The casing 12 is attached to the mounting base 5A of the side frame 5 that constitutes the lower traveling body 2. The casing 12 has a frame-side casing 13 attached to the mounting base 5A, an intermediate casing 14 attached to the frame-side casing 13, a motor-side casing 15 attached to the intermediate casing 14, and a cover 16 attached to the motor-side casing 15, and constitutes the outer shell of the traveling device 11.

[0019] The frame-side casing 13 is formed into a cylindrical shape having an outer diameter equal to that of the mounting base 5A of the side frame 5. The frame-side casing 13 is fixed to the mounting base 5A together with the intermediate casing 14 using a plurality of bolts 17 (only one bolt is illustrated). An annular internal tooth 13A is formed over the entire circumference on the inner peripheral side of the frame-side casing 13, and a second-stage planetary gear 35 to be described later meshes with the internal tooth 13A.

[0020] The intermediate casing 14 is formed in a cylindrical shape with a smaller diameter than the frame-side casing 13, and a large-diameter annular flange portion 14A is provided on one end in the axial direction (the mounting base 5A side). Multiple bolts 17 are inserted through the flange portion 14A and the frame-side casing 13, and these multiple bolts 17 are screwed into the mounting base 5A. In this way, the frame-side casing 13 and the intermediate casing 14 are fixed together to the mounting base 5A using multiple bolts 17. Annular internal teeth 14B are formed around the entire inner circumference of the intermediate casing 14, and the first-stage planetary gear 31, which will be described later, meshes with the internal teeth 14B.

[0021] The motor-side casing 15 is fixed to the end face of the other axial end (travel motor 22 side) of the intermediate casing 14 using a plurality of bolts 18 (only one is shown). The motor-side casing 15 has a disc-shaped wall portion 15A that closes the other axial end of the intermediate casing 14, and a cylindrical portion 15B that protrudes in the other axial direction from the periphery of the wall portion 15A. A large-diameter hole 15C and a small-diameter hole 15D smaller in diameter than the large-diameter hole 15C are formed in the wall portion 15A, both penetrating through it in the axial direction. The large-diameter hole 15C is located in the center of the wall portion 15A, and a transmission shaft 26, etc., which will be described later, is inserted through it. The small-diameter hole 15D is located above the large-diameter hole 15C, and a pinion gear 39, which will be described later, is inserted through it.

[0022] The cover 16 is fixed to the other axial end face of the cylindrical portion 15B that constitutes the motor-side casing 15 using a plurality of bolts 19 (only one is shown). The cover 16 has a large diameter hole 16A and a small diameter hole 16B that is smaller in diameter than the large diameter hole 16A, both of which are formed to penetrate through the cover 16 in the axial direction. The large diameter hole 16A is positioned concentrically with the large diameter hole 15C of the motor-side casing 15 and has the same hole diameter as the large diameter hole 15C. The small diameter hole 16B is positioned concentrically with the small diameter hole 15D of the motor-side casing 15 and has the same hole diameter as the small diameter hole 15D.

[0023] On the outer surface of the cover 16 opposite to the casing 12, a lid mounting portion 16C and a motor mounting portion 16D are formed. The lid mounting portion 16C is formed as an annular flat surface formed on the periphery of the large-diameter hole 16A, and the lid 20, which will be described later, is attached thereto. The motor mounting portion 16D is formed in a cylindrical shape surrounding the small-diameter hole 16B from the outer circumference, and the travel motor 22 is attached thereto.

[0024] The lid 20 is attached to the lid mounting portion 16C of the cover 16 using multiple bolts 21 (only one is shown), closing the large-diameter hole 16A of the cover 16. A recessed portion 20A is formed on the inner surface of the lid 20 that faces the casing 12, and a bearing 28, which will be described later, is attached to the recessed portion 20A.

[0025] The travel motor 22 is attached to the motor mounting portion 16D of the cover 16 using bolts or the like (not shown), closing the small diameter hole 16B of the cover 16. The travel motor 22 is, for example, a hydraulic motor, and the output shaft 22A is rotated by supplying and discharging pressurized oil from a hydraulic pump (not shown). The output shaft 22A of the travel motor 22 protrudes into the casing 12 through the small diameter hole 16B of the cover 16. A male spline (shaft spline) 22B is formed on the protruding end of the output shaft 22A, and the male spline 22B is fitted into the female spline 39D of the pinion gear 39. In this way, the travel motor 22 is mounted on the outside of the casing 12 with the output shaft 22A protruding into the casing 12. Here, since the motor mounting portion 16D of the cover 16 is cylindrical and surrounds the small diameter hole 16B from the outer circumference, a sealed closed space 23 is formed between the travel motor 22 and the cover 16.

[0026] The transmission gear 24 is rotatably mounted within the casing 12, positioned between the pinion gear 39 and the planetary gear reduction mechanism 29. The transmission gear 24 transmits the rotation of the pinion gear 39 to the sun gear 30 in a reduced state. The transmission gear 24 is a spur gear, and a cylindrical boss 24A is provided at the center of the transmission gear 24. The boss 24A of the transmission gear 24 is rotatably supported by bearings 25 mounted in the large diameter hole 15C of the motor-side casing 15 and the large diameter hole 16A of the cover 16. A female spline is formed on the inner circumference of the boss 24A, and this female spline is fitted to the male spline 26A of the transmission shaft 26. Teeth 24B are formed on the outer circumference of the transmission gear 24, and the teeth 24B mesh with the teeth 39E of the pinion gear 39.

[0027] The transmission shaft 26 is spline-coupled to the boss 24A of the transmission gear 24, and transmits the rotation of the transmission gear 24 to the sun gear 30. The transmission shaft 26 is formed from a cylindrical rod, and the sun gear 30 is integrally formed on one end in the axial direction (the mounting base 5A side). A male spline 26A is formed on the other end in the axial direction of the transmission shaft 26, and the male spline 26A is fitted into a female spline formed on the boss 24A of the transmission gear 24. Therefore, the transmission shaft 26 rotates integrally with the transmission gear 24. The end face of the stopper 27 abuts against the end face of the other end in the axial direction of the transmission shaft 26. The stopper 27 is rotatably supported by a bearing 28 attached to a recess 20A of the cover 20, and positions the transmission shaft 26 in the axial direction.

[0028] The first-stage planetary gear reduction mechanism 29 is located inside the casing 12 adjacent to the transmission gear 24. The planetary gear reduction mechanism 29 consists of a sun gear 30, a plurality of planetary gears 31 (only one is shown), and a carrier 32, and reduces the rotation of the sun gear 30 and transmits it to the second-stage sun gear 34.

[0029] The sun gear 30 is integrally formed on one axial end of the transmission shaft 26. The sun gear 30 rotates in sync with the transmission gear 24 around the axis (center of rotation) A. Multiple planetary gears 31 mesh with the sun gear 30 and the internal teeth 14B of the intermediate casing 14, and revolve around the sun gear 30 while rotating on their own axis. The carrier 32 has multiple pins 32A and bearings 32B corresponding to the planetary gears 31, and rotatably supports the planetary gears 31. A female spline 32C is formed in the center of the carrier 32, and the female spline 32C is fitted to the male spline 34A of the sun gear 34, which will be described later. The planetary gear reduction mechanism 29 reduces the rotation of the sun gear 30 using the planetary gears 31 and transmits the revolution of the planetary gears 31 to the second-stage planetary gear reduction mechanism 33 via the carrier 32.

[0030] The second-stage planetary gear reduction mechanism 33 is located inside the casing 12, adjacent to the first-stage planetary gear reduction mechanism 29. The planetary gear reduction mechanism 33 consists of a sun gear 34, a plurality of planetary gears 35 (only one is shown), and a carrier 36, and reduces the rotation of the sun gear 34 and transmits it to the rotating shaft 37.

[0031] The sun gear 34 is spline-coupled to the first-stage carrier 32 and rotates integrally with the carrier 32. A male spline 34A is formed on the other axial end of the sun gear 34 (towards the travel motor 22), and the male spline 34A is engaged with a female spline 32C on the carrier 32. Multiple planetary gears 35 mesh with the sun gear 34 and the internal teeth 13A of the frame-side casing 13, and revolve around the sun gear 34 while rotating on their own axis. The carrier 36 has multiple pins 36A and bearings 36B corresponding to the planetary gears 35, and rotatably supports the planetary gears 35. A female spline 36C is formed in the center of the carrier 36, and the female spline 36C is engaged with a male spline 37B on the rotating shaft 37. The planetary gear reduction mechanism 33 reduces the rotation of the sun gear 34 using the planetary gears 35 and transmits the revolution of the planetary gears 35 to the rotating shaft 37 via the carrier 36.

[0032] The rotating shaft 37 is mounted on the mounting base 5A of the side frame 5 and transmits the rotation of the carrier 36 of the planetary gear reduction mechanism 33 to the drive wheel 8. The axial middle portion of the rotating shaft 37 is rotatably supported on the mounting base 5A via a bearing 38. A male spline 37A is formed on one axial end of the rotating shaft 37, and the male spline 37A is fitted into a female spline 8A formed in the center of the drive wheel 8. A male spline 37B is formed on the other axial end of the rotating shaft 37, and the male spline 37B is fitted into a female spline 36C of the second stage carrier 36. Therefore, the rotation of the second stage carrier 36 is transmitted to the drive wheel 8 via the rotating shaft 37.

[0033] The lubricating oil L is held within the casing 12. The lubricating oil L is filled to a position higher than, for example, the axis A of the sun gear 30. This configuration ensures that sufficient lubricating oil is supplied to the planetary gear reduction mechanisms 29, 33, etc., which are located within the casing 12.

[0034] Next, the pinion gear 39 used in this embodiment will be described with reference to Figures 3 to 6.

[0035] The pinion gear 39 is rotatably positioned within the casing 12. The pinion gear 39 is spline-coupled to the output shaft 22A of the travel motor 22 and transmits the rotation of the travel motor 22 to the transmission gear 24. The pinion gear 39 has a cylindrical boss 39A, and a cylindrical bearing support portion 39B having a smaller outer diameter than the boss 39A is integrally formed on one axial end of the boss 39A (the mounting base 5A side). Similarly, a cylindrical bearing support portion 39C having a smaller outer diameter than the boss 39A is integrally formed on the other axial end of the boss 39A (the travel motor 22 side).

[0036] The bearing support portion 39B of the pinion gear 39 is rotatably supported by a bearing 40 mounted in a small-diameter hole 15D of the motor-side casing 15, and the bearing support portion 39C is rotatably supported by a bearing 41 mounted in a small-diameter hole 16B of the cover 16. The axis (center of rotation) B of the pinion gear 39 is positioned higher by a height H than the axis A of the sun gear 30 (see Figure 2). This configuration allows the travel motor 22 to be positioned away from the ground, preventing it from coming into contact with rocks or other objects protruding from the ground when the hydraulic excavator 1 is traveling.

[0037] A female spline 39D is formed on the inner circumference of the boss 39A, and the female spline 39D is engaged with the male spline 22B of the travel motor 22 (output shaft 22A). Teeth 39E are formed on the outer circumference of the boss 39A, and the teeth 39E mesh with the teeth 24B of the transmission gear 24. Therefore, the rotation of the travel motor 22 is transmitted to the transmission gear 24 via the pinion gear 39, and then, after being reduced by the transmission gear 24, is transmitted to the first stage sun gear 30 via the transmission shaft 26.

[0038] A cylindrical projection 39F is integrally formed on one axial end (mounting base 5A side) of the pinion gear 39, projecting from the bearing support portion 39B toward the planetary gear reduction mechanism 29. Two notches 39G are formed on the projection 39F at an angle of 180 degrees, connecting the outer and inner surfaces of the projection 39F. The notches 39G guide the lubricating oil L that is ejected from the meshing portion between the internal teeth 14B of the intermediate casing 14 and the first-stage planetary gear 31 toward the bearing 40, when it is scattered onto the outer surface of the bearing support portion 39B. As a result, sufficient lubricating oil L is supplied to the spline connection between the output shaft 22A of the travel motor 22 and the pinion gear 39, and this spline connection can be properly lubricated.

[0039] On the other hand, four oil grooves 39H are formed at 90-degree angle intervals on the inner circumferential surface of the bearing support portion 39C located on the other axial end of the pinion gear 39. These oil grooves 39H include an axial oil groove 39H1 that extends axially along the inner circumferential surface of the bearing support portion 39C, and a radial oil groove 39H2 that extends radially along the end face 39J of the bearing support portion 39C, connecting the axial oil groove 39H1 to the outer circumferential surface of the bearing support portion 39C. The oil grooves 39H guide the lubricating oil L supplied to the female spline 39D through the notch 39G to the outer circumferential surface of the bearing support portion 39C. As a result, lubricating oil L is supplied to the bearing 41 that supports the bearing support portion 39C on the other axial end of the pinion gear 39, and the bearing 41 can be properly lubricated.

[0040] Here, when the male spline 22B formed on the output shaft 22A of the travel motor 22 is fitted to the female spline 39D of the pinion gear 39, the outer circumferential surface of the base end (root) of the output shaft 22A, where the male spline 22B is not formed, fits with almost no gap against the inner circumferential surface of the bearing support portion 39C of the pinion gear 39. For this reason, if the oil groove 39H is not formed, the lubricating oil L supplied to the female spline 39D will be blocked at the boundary between the outer circumferential surface of the base end of the output shaft 22A and the male spline 22B, making it difficult for it to flow to the end face 39J of the bearing support portion 39C.

[0041] In contrast, in this embodiment, four oil grooves 39H formed on the inner circumferential surface of the bearing support portion 39C create a flow path for lubricating oil L between the output shaft 22A and the bearing support portion 39C. This allows the lubricating oil L supplied to the female spline 39D to flow through the oil grooves 39H to the outer circumferential surface of the bearing support portion 39C, thereby supplying sufficient lubricating oil L to the bearing 41 that supports the bearing support portion 39C.

[0042] The oil hole 42 is located in the lower part of the cover 16 below the bearing 41, specifically near the bottom of the inner circumferential surface of the cylindrical motor mounting portion 16D of the cover 16. The oil hole 42 connects the closed space 23 formed between the cover 16 and the travel motor 22 with the internal space of the casing 12. This allows the lubricating oil L supplied to the bearing 41 to be returned to the casing 12 through the oil hole 42, preventing the lubricating oil L from flowing towards the travel motor 22.

[0043] The hydraulic excavator 1 according to this embodiment has the travel device 11 described above. When the travel motor 22 operates and the output shaft 22A rotates, the rotation of the output shaft 22A is reduced as it is transmitted from the pinion gear 39 to the transmission gear 24. The transmission shaft 26, which is spline-coupled to the transmission gear 24, outputs the reduced rotation to the sun gear 30 of the first-stage planetary gear reduction mechanism 29.

[0044] When the first-stage sun gear 30 rotates, the planetary gear 31, which meshes with the sun gear 30 and the internal teeth 14B of the intermediate casing 14, rotates on its own axis and revolves around the sun gear 30, and this revolution of the planetary gear 31 is transmitted to the carrier 32. The reduced rotation of the carrier 32 is transmitted to the sun gear 34 of the second-stage planetary gear reduction mechanism 33, and the planetary gear 35, which meshes with the sun gear 34 and the internal teeth 13A of the frame-side casing 13, rotates on its own axis and revolves around the sun gear 34. This revolution of the planetary gear 35 is transmitted to the carrier 36, and then transmitted to the drive wheel 8 from the rotating shaft 37 spline-coupled to the carrier 36.

[0045] In this way, the rotation of the travel motor 22 is reduced in three stages by the transmission gear 24 and the planetary gear reduction mechanism 29, 33 before being transmitted to the drive wheel 8. As a result, the drive wheel 8 rotates with a large torque, and the crawler 9 wound around the drive wheel 8 and the idler wheel 7 is driven in a circular motion, thereby enabling the hydraulic excavator 1 to move.

[0046] The casing 12 of the running gear 11 is filled with lubricating oil L to a position higher than the axis A of the sun gear 30. As a result, when the running gear 11 is in operation, the bearings 25, the spline connection between the transmission gear 24 and the transmission shaft 26, the planetary gear reduction mechanisms 29 and 33, the spline connection between the carrier 36 and the rotating shaft 37, the bearings 38, etc. can be lubricated by the lubricating oil L. In addition, the meshing portion between the transmission gear 24 (tooth 24B) and the pinion gear 39 (tooth 39E) can be lubricated by the lubricating oil L splashed up by the rotation of the transmission gear 24.

[0047] Here, the spline connection between the output shaft 22A (male spline 22B) of the travel motor 22 and the pinion gear 39 (female spline 39D) wears down due to repeated contact between the tooth surfaces caused by vibrations during the operation of the travel device 11. In contrast, in this embodiment, sufficient lubricating oil L is supplied to the spline connection between the output shaft 22A and the pinion gear 39. The flow of lubricating oil L supplied to the female spline 39D of the pinion gear 39 will be explained below with reference to Figure 4.

[0048] When the running gear 11 is in operation, lubricating oil L supplied to the meshing portion between the internal teeth 14B of the intermediate casing 14 and the planetary gear 31 is ejected from this meshing portion toward the bearing 40 in the direction indicated by arrow F1, and the bearing 40 can be lubricated by this lubricating oil L. As the lubricating oil L ejected toward the bearing 40 flows along the outer circumferential surface of the protruding portion 39F that protrudes from the bearing support portion 39B of the pinion gear 39, it flows into the inner circumference of the bearing support portion 39B through the notch portion 39G, as indicated by arrow F2.

[0049] The lubricating oil L that flows into the inner circumference of the bearing support portion 39B splits into a flow in the direction of arrow F3 (radial direction) and a flow in the direction of arrow F4 (axial direction). The lubricating oil L that flows in the direction of arrow F3 is led out to the outer surface of the protrusion 39F through the notch portion 39G and supplied to the bearing 40. On the other hand, the lubricating oil L that flows in the direction of arrow F4 flows along the female spline 39D to the bearing support portion 39C. In this way, the lubricating oil L that flows into the inner circumference of the bearing support portion 39B through the notch portion 39G flows along the female spline 39D to the bearing support portion 39C, thereby supplying lubricating oil L to the entire area of ​​the female spline 39D. As a result, the spline connection between the output shaft 22A and the pinion gear 39 can be properly lubricated with lubricating oil L, preventing the tooth surfaces of the male spline 22B and the female spline 39D from contacting and wearing down due to vibrations during the operation of the traveling device 11, thereby increasing the durability of the output shaft 22A and the pinion gear 39.

[0050] Furthermore, four oil grooves 39H are formed on the inner circumferential surface of the bearing support portion 39C. As a result, even when the male spline 22B of the output shaft 22A is fitted into the female spline 39D of the pinion gear 39, and the outer circumferential surface of the base end of the output shaft 22A is fitted with the inner circumferential surface of the bearing support portion 39C with almost no gap, the oil grooves 39H ensure a flow path for lubricating oil L between the output shaft 22A and the inner circumferential surface of the bearing support portion 39C. Consequently, the lubricating oil L that has flowed into the inner circumferential side of the bearing support portion 39B can be smoothly circulated along the female spline 39D in the direction of arrow F4, and the spline connection between the output shaft 22A and the pinion gear 39 can be efficiently lubricated.

[0051] The lubricating oil L, guided along the female spline 39D to the inner circumferential surface of the bearing support portion 39C, flows from the axial oil groove 39H1 of the oil groove 39H to the radial oil groove 39H2, as indicated by arrows F5 and F6, and is supplied to the bearing 41 from the end face 39J of the bearing support portion 39C. In this way, by forming the oil groove 39H on the inner circumferential surface of the bearing support portion 39C located on the other axial end side of the pinion gear 39, sufficient lubricating oil L can be supplied to the bearing 41, which is far from the planetary gear reduction mechanism 29, through the oil groove 39H, and the bearing 41 can be properly lubricated.

[0052] The lubricating oil L supplied to the bearing 41 flows down into the closed space 23 formed between the cover 16 and the travel motor 22, and then returns to the casing 12 through the oil hole 42, as indicated by arrow F7. By providing the oil hole 42 that connects the closed space 23 and the internal space of the casing 12 in this way, the lubricating oil L does not accumulate in the closed space 23, and a predetermined amount of lubricating oil L can be held in the casing 12. In addition, it is possible to prevent excess lubricating oil L from flowing to the travel motor 22 side.

[0053] Thus, the travel device 11 according to the embodiment includes a travel motor 22 mounted on a casing 12 with an output shaft 22A protruding into the casing 12, a male spline 22B formed on the output shaft 22A of the travel motor 22, a pinion gear 39 rotatably supported within the casing 12 via bearings 40, 41, with a female spline 39D formed on its inner circumference that fits into the male spline 22B and teeth 39E formed on its outer circumference, and within the casing 12 The system includes planetary gear reduction mechanisms 29 and 33 provided to reduce the rotation of the pinion gear 39 and output the reduced rotation, and a transmission gear 24 provided between the pinion gear 39 and the planetary gear reduction mechanism 29 to transmit the rotation of the pinion gear 39 to the sun gear 30 of the planetary gear reduction mechanism 29. Lubricating oil L for lubricating the planetary gear reduction mechanisms 29 and 33 is held inside the casing 12, and the axis B of the pinion gear 39 is positioned higher than the axis A of the sun gear 30. A notch 39G is provided on one axial end of the pinion gear 39 to guide the lubricating oil L supplied to the outer circumference of the pinion gear 39 to the female spline 39D.

[0054] In this configuration, the lubricating oil L held within the casing 12 is splashed up by the planetary gear reduction mechanisms 29 and 33 and scattered to the outer circumference of the pinion gear 39, and then guided to the female spline 39D through the notch 39G. This allows for proper lubrication of the spline connection between the output shaft 22A (male spline 22B) of the travel motor 22 and the pinion gear 39 (female spline 39D).

[0055] In this embodiment, a projection 39F is provided on one axial end of the pinion gear 39, projecting axially from a bearing support portion 39B supported by a bearing 40 toward the planetary gear reduction mechanism 29, and a notch 39G connects the outer and inner surfaces of the projection 39F. With this configuration, when lubricating oil L is ejected toward the bearing 40 from the meshing portion between the planetary gear 31 of the planetary gear reduction mechanism 29 and the internal teeth 14B of the casing 12 (intermediate casing 14), this lubricating oil L flows over the outer surface of the projection 39F of the pinion gear 39 and is then guided to the inner surface of the projection 39F through the notch 39G. This allows sufficient lubricating oil L to be supplied to the female spline 39D of the pinion gear 39.

[0056] In this embodiment, an oil groove 39H is formed on the inner circumferential surface of the other axial end of the pinion gear 39. This groove connects the female spline 39D to the other axial end of the pinion gear 39 and guides the lubricating oil L supplied to the female spline 39D through the notch 39G to the bearing 41 that supports the other axial end of the pinion gear 39. With this configuration, even when the male spline 22B of the output shaft 22A is fitted into the female spline 39D of the pinion gear 39, and the outer circumferential surface of the base end of the output shaft 22A is fitted into the inner circumferential surface of the bearing support portion 39C, the oil groove 39H ensures a flow path for the lubricating oil L between the output shaft 22A and the inner circumferential surface of the bearing support portion 39C. As a result, the lubricating oil L that flows into the inner circumference of the bearing support portion 39B can be smoothly circulated along the female spline 39D, and the spline connection between the output shaft 22A and the pinion gear 39 can be efficiently lubricated. Furthermore, the lubricating oil L can be supplied to the bearing 41 that supports the bearing support portion 39C of the pinion gear 39 through the oil groove 39H, and the bearing 41, which is far from the planetary gear reduction mechanism 29, can be properly lubricated.

[0057] In this embodiment, the travel motor 22 is mounted on the outside of the casing 12 with its output shaft 22A protruding into the casing 12. The casing 12 is provided with an oil hole 42 located below the output shaft 22A, which returns the lubricating oil L that has flowed between the casing 12 and the travel motor 22 back into the casing 12. This configuration allows a predetermined amount of lubricating oil L to be held inside the casing 12, and prevents excess lubricating oil L from flowing to the travel motor 22.

[0058] Next, Figure 7 shows a running gear according to a second embodiment of the present invention, the feature of which is the provision of a magnet for capturing wear particles mixed in the lubricating oil. In this embodiment, the same reference numerals are used for the same components as in the first embodiment, and their descriptions are omitted.

[0059] In Figure 7, the magnet 43 is located adjacent to the oil hole 42 on the cover 16 that constitutes the casing 12. Specifically, the magnet 43 is attached to the lowest part of the inner circumferential surface of the cylindrical motor mounting portion 16D of the cover 16 using a bolt 44. The magnet 43 is positioned in the middle of the flow path through which lubricating oil L supplied to the spline connection portion between the output shaft 22A of the travel motor 22 and the pinion gear 39 flows from the closed space 23 formed between the cover 16 and the travel motor 22 to the oil hole 42, and captures wear particles mixed in with this lubricating oil L.

[0060] The travel device according to the second embodiment has the magnet 43 described above, and there is no particular difference from the first embodiment in terms of its basic function and effect of properly lubricating the spline joint between the output shaft 22A of the travel motor 22 and the pinion gear 39. However, according to the second embodiment, even if wear particles generated at the spline joint are mixed into the lubricating oil L that is lubricated at the spline joint between the output shaft 22A of the travel motor 22 and the pinion gear 39 and led into the closed space 23, these wear particles mixed into the lubricating oil L can be captured by the magnet 43. As a result, wear particles can be removed from the lubricating oil L that returns into the casing 12 through the oil hole 42, and the planetary gear reduction mechanism 29, 33, etc. can always be lubricated with clean lubricating oil L. Note that the mounting position of the magnet 43 is not limited to the position shown in Figure 7, but can be any position upstream of the oil hole 42 in the flow direction of the lubricating oil L.

[0061] In this embodiment, an example is shown in which two notches 39G are provided on the protruding portion 39F of the pinion gear 39 at an angular interval of 180 degrees. However, the present invention is not limited to this, and for example, as shown in the modified example in Figure 8, four notches 39G may be provided on the protruding portion 39F of the pinion gear 39 at an angular interval of 90 degrees. By providing four notches 39G, more lubricating oil L can be guided from the outer circumferential surface to the inner circumferential surface of the protruding portion 39F and supplied to the female spline 39D. As a result, the spline connection between the output shaft 22A of the travel motor 22 and the pinion gear 39 can be lubricated efficiently.

[0062] Furthermore, in this embodiment, a cylindrical projection 39F is provided from the bearing support portion 39B of the pinion gear 39, and a notch 39G is provided in this projection 39F. However, the present invention is not limited to this, and may be configured as, for example, the pinion gear 45 of other modifications shown in Figure 9.

[0063] Specifically, the pinion gear 45, like the pinion gear 39 according to the first embodiment, is composed of a boss 45A, bearing support portions 45B and 45C, a female spline 45D, and teeth 45E, but does not have a protruding portion 39F like the pinion gear 39. Instead, two notches 45F are formed on the end face of the bearing support portion 45B located on one axial end of the pinion gear 45. Furthermore, an oil groove 45G, consisting of an axial oil groove 45G1 and a radial oil groove 45G2, is formed on the inner circumferential surface of the bearing support portion 45C located on the other axial end of the pinion gear 45.

[0064] Even in a traveling device equipped with a pinion gear 45 configured in this way, the lubricating oil L ejected from the meshing portion between the internal teeth 14B of the intermediate casing 14 and the planetary gear 31 toward the bearing 40 can be guided from the outer circumference to the inner circumference of the bearing support portion 45B through the notch portion 45F. This allows sufficient lubricating oil L to be supplied to the female spline 45D of the pinion gear 45, and the spline connection portion between the output shaft 22A of the traveling motor 22 and the pinion gear 45 to be properly lubricated. [Explanation of Symbols]

[0065] 11. Running gear 12 Casing 22. Travel motor 22A output shaft 22B Male Spline 24 Transmission gears 29,33 Planetary gear reduction mechanism 39, 45 pinion gear 39B,39C,45B,45C, bearing support part 39D, 45D Female spline 39E, 45E teeth 39F Protrusion 39G,45F Notch 39H,45G Oil groove 40, 41 bearings 42 Oil hole 43 Magnets

Claims

1. A travel motor is mounted in a casing, with its output shaft protruding into the casing, A male spline formed on the output shaft of the aforementioned travel motor, A pinion gear is rotatably supported within the casing via a bearing, with a female spline formed on its inner circumference that fits into the male spline, and teeth formed on its outer circumference. A planetary gear reduction mechanism provided within the casing reduces the rotation of the pinion gear and outputs the result; The system includes a transmission gear provided between the pinion gear and the planetary gear reduction mechanism, which transmits the rotation of the pinion gear to the sun gear of the planetary gear reduction mechanism. The casing contains lubricating oil for lubricating the planetary gear reduction mechanism. In a traveling device in which the axis of the pinion gear is positioned higher than the axis of the sun gear, A traveling device characterized in that a notch is provided on one axial end of the pinion gear to guide the lubricating oil supplied to the outer circumference of the pinion gear to the female spline.

2. The traveling device according to claim 1, wherein a projection is provided on one axial end of the pinion gear, projecting axially from a bearing support portion supported by the bearing toward the planetary gear reduction mechanism, and the notch portion connects the outer circumferential surface and the inner circumferential surface of the projection.

3. The traveling device according to claim 1, characterized in that an oil groove is formed on the inner circumferential surface of the other axial end of the pinion gear, connecting the female spline and the other axial end of the pinion gear, and guiding the lubricating oil supplied to the female spline through the notch to the bearing that supports the other axial end of the pinion gear.

4. The aforementioned travel motor is mounted on the outside of the casing with the output shaft protruding into the casing. The traveling device according to claim 1, characterized in that the casing is provided with an oil hole located below the output shaft that returns the lubricating oil that has flowed between the casing and the traveling motor back into the casing.

5. The running gear according to claim 4, characterized in that the casing is provided with a magnet for capturing wear particles mixed in with the lubricating oil that is returned to the casing through the oil holes.

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