Axle device for traveling

Abstract

To prevent a lubrication oil scraped by a differential mechanism from leaking from an air breather to the outside, facilitate downsizing, and achieve reduction of costs.SOLUTION: An air breather 52 which lets air inside and outside of a casing 13 is disposed in a left speed reduction mechanism chamber 15B which is provided communicating with a differential mechanism chamber 14C. Thus, the air breather 52 is disposed in the left speed reduction mechanism chamber 15B which is spaced apart from the differential mechanism chamber 14C in a lateral direction. Hence, the structure can prevent a lubrication oil 51 scraped in the differential mechanism chamber 14C from leaking to the outside through the air breather 52.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a traveling axle device that is preferably used in wheeled construction machines such as wheel loaders and wheeled hydraulic excavators. [Background technology]

[0002] A wheel loader is a well-known representative example of a wheeled construction machine. A wheel loader is configured to include a vehicle body equipped with a traveling axle device that drives left and right wheels, and a work device attached to the vehicle body. An engine, a torque converter, a transmission, etc. are mounted on the vehicle body, and the rotational force of the engine is transmitted to the transmission via the torque converter. In addition, the traveling axle device is connected to the output shaft of the transmission, and transmits the rotational force to the left and right wheels to rotate them.

[0003] The traveling axle device is composed of a hollow structure extending in the left-right direction and includes a casing having a reduction mechanism chamber on both the left and right sides of the differential mechanism chamber, a differential mechanism provided in the differential mechanism chamber of the casing for distributing the rotational force of the transmission output shaft to the left and right rotating shafts, left and right planetary gear reduction mechanisms provided in the left and right reduction mechanism chambers of the casing for reducing the rotation of the left and right rotating shafts, and left and right axle shafts provided on the left and right sides within the casing to transmit the rotation reduced by the left and right planetary gear reduction mechanisms.

[0004] The casing is filled with lubricating oil, which lubricates and cools the rotating and meshing parts of the differential mechanism, planetary gear reduction mechanism, etc., and reduces noise. The lubricating oil is filled, for example, up to about half the casing (to the height of the axis of the rotating shaft and axle shaft), and is sealed in so as not to leak out.

[0005] On the other hand, since the air pressure inside the casing increases due to changes in temperature, etc., an air breather is provided to prevent damage to sealing members, etc. This air breather can let air in and out between the inside of the casing and the outside (Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2011-69455 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the configuration of Patent Document 1, the air breather is disposed above the differential mechanism of the casing. In this mounting position of the air breather, if the bevel gear constituting the differential mechanism scoops up the lubricating oil, there is a risk that the scattered lubricating oil will leak to the outside through the air breather. Therefore, in Patent Document 1, a baffle plate is disposed between the bevel gear and the air breather. As a result, in Patent Document 1, the traveling axle device becomes larger in size in order to secure space for providing the baffle plate. In addition, there is a problem that the cost increases due to the increase in the number of parts and the man-hours required for mounting.

[0008] The present invention has been made in consideration of the problems with the conventional technology described above, and an object of the present invention is to provide a traveling axle device that prevents lubricating oil scooped up by the differential mechanism from leaking to the outside through the air breather, thereby promoting miniaturization and reducing costs. [Means for solving the problem]

[0009] The present invention relates to a traveling axle device comprising: a casing consisting of a hollow structure extending in the left-right direction and having a differential mechanism chamber and a reduction mechanism chamber provided on both the left and right sides of the differential mechanism chamber in communication with the differential mechanism chamber; a differential mechanism provided in the differential mechanism chamber of the casing and distributing the rotational force of a drive source to left and right rotating shafts; left and right planetary gear reduction mechanisms provided in the left and right reduction mechanism chambers of the casing and reducing the rotation of the left and right rotating shafts; left and right axle shafts provided on both the left and right sides of the casing and to which the rotation reduced by the left and right planetary gear reduction mechanisms is transmitted; and an air breather for letting air in and out between the inside and outside of the casing, wherein the air breather is positioned in either the left or right reduction mechanism chamber. Effect of the Invention

[0010] According to the present invention, it is possible to prevent lubricating oil scooped up by the differential mechanism from leaking out from the air breather, thereby promoting size reduction and reducing costs. [Brief description of the drawings]

[0011] [Figure 1] 1 is a left side view showing a wheel loader equipped with a traveling axle device according to an embodiment. FIG. [Diagram 2] FIG. 2 is a perspective view of the front axle device as seen from the front. [Diagram 3] 3 is a cross-sectional view showing the internal structure of the front axle device taken along the line III-III in FIG. 2. [Figure 4] 4 is an enlarged cross-sectional view of a differential mechanism, left and right planetary gear reduction mechanisms, etc. in FIG. 3. [Diagram 5] 5 is a cross-sectional view showing the internal structure of the front axle device as viewed from the direction of arrow VV in FIG. 4. [Figure 6] 6 is a cross-sectional view showing the casing, the planetary gear reduction mechanism, and the air breather taken from the direction of arrows VI-VI in FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of a traveling axle device will be described in detail with reference to Figures 1 to 6, taking as an example a case where the device is mounted on a wheel loader. Note that in the embodiment, the traveling direction of the wheel loader will be described as the front-rear direction, and the direction perpendicular to the traveling direction of the wheel loader will be described as the left-right direction.

[0013] In FIG. 1, the wheel loader 1 is made up of a rear body 2, a front body 3 connected to the front side of the rear body 2 so that it can swing left and right, rear wheels 4 provided on both left and right sides of the rear body 2, front wheels 5 provided on both left and right sides of the front body 3 (only the left side of each is shown), a working device 6 provided on the front side of the front body 3 so that it can be raised and lowered, and a rear axle unit 11 and a front axle unit 12, which will be described later.

[0014] The rear vehicle body 2 is equipped with an engine 7, which serves as a drive source, a torque converter 8, a transmission 9, a hydraulic pump (not shown), etc. The transmission 9 is connected to a rear axle unit 11 via a propeller shaft 9A extending in the front-rear direction. The transmission 9 is also connected to a front axle unit 12 via a propeller shaft 9B. A cab 10 in which an operator sits is provided on the upper side of the rear vehicle body 2.

[0015] The rear axle device 11 is disposed below the rear vehicle body 2. The rear axle device 11 is formed to extend in the left-right direction, and the rear wheels 4 are attached to the left and right ends thereof, respectively.

[0016] On the other hand, the front axle unit 12 is located below the front vehicle body 3. This front axle unit 12 is formed to extend in the left-right direction like the rear axle unit 11, and front wheels 5 are attached to the left and right ends thereof, respectively.

[0017] Here, the rear axle device 11 and the front axle device 12 constitute a traveling axle device. The rear axle device 11 and the front axle device 12 are configured in the same manner except that the connection positions of the propeller shafts 9A, 9B are different. For this reason, in this embodiment, the configuration of the front axle device 12 will be described in detail, and a description of the configuration of the rear axle device 11 will be omitted.

[0018] The front axle device 12 is connected to the propeller shaft 9B to rotate and drive the left and right front wheels 5. As shown in Figures 2 to 5, the front axle device 12 includes a casing 13, a differential mechanism 21, a left planetary gear reduction mechanism 28, a right planetary gear reduction mechanism 34, a left axle shaft 39, a right axle shaft 40, and an air breather 52, which will be described later.

[0019] The casing 13 constitutes the outer shape of the front axle device 12. The casing 13 is a hollow structure extending in the left-right direction, and has a structure in which a left reduction mechanism chamber 15B and a right reduction mechanism chamber 16B are provided on both the left and right sides of a differential mechanism chamber 14C described later, which are connected to the differential mechanism chamber 14C. The casing 13 includes a hollow differential body 14 located in the middle in the left-right direction, a left axle tube 15 located on the left side of the differential body 14, and a right axle tube 16 located on the right side of the differential body 14. The differential body 14 accommodates a differential mechanism 21, a left brake mechanism 41, and a right brake mechanism 46. A left axle shaft 39 is rotatably supported in the left axle tube 15, and a right axle shaft 40 is rotatably supported in the right axle tube 16. A front wheel 5 is attached to each of the left and right axle shafts 39, 40 at their respective distal ends.

[0020] 3, the differential body 14 is formed as a generally cylindrical body centered on an axis XX extending in the left-right direction (axial direction), and both left and right ends are open. The differential body 14 accommodates a differential mechanism 21 and left and right brake mechanisms 41, 46 inside.

[0021] A left partition wall 14A is provided integrally with the left side of the differential body 14. Meanwhile, a right partition wall 14B is provided integrally with the right side of the differential body 14. The left partition wall 14A and the right partition wall 14B protrude radially inward from the inner circumferential surface at a position recessed from the open end.

[0022] Inside the differential body 14, the space between the left bulkhead 14A and the right bulkhead 14B constitutes a differential mechanism chamber 14C. Inside the differential body 14, the space to the left of the left bulkhead 14A constitutes a left brake chamber 14D, and the space to the right of the right bulkhead 14B constitutes a right brake chamber 14E.

[0023] The differential mechanism chamber 14C houses the differential mechanism 21, the left brake chamber 14D houses the left brake mechanism 41, and the right brake chamber 14E houses the right brake mechanism 46. A protruding tube 14F that protrudes toward the transmission 9 is provided on the rear side (the rear axle device 11 side) of the differential body 14. The protruding tube 14F opens into the differential mechanism chamber 14C, and an input shaft 18, which will be described later, is rotatably supported within the protruding tube 14F.

[0024] The left axle tube 15 is formed as a cylinder extending from the left end of the differential body 14 toward the left side so as to reduce in diameter. The right side (differential body 14 side) of the left axle tube 15 is a cylindrical section 15A having an outer diameter dimension equivalent to that of the differential body 14. Inside the left axle tube 15, the inner periphery side of the cylindrical section 15A located to the left of the differential mechanism chamber 14C becomes the left reduction mechanism chamber 15B, and the left side of the left reduction mechanism chamber 15B becomes the left axle chamber 15C. The left planetary gear reduction mechanism 28 is accommodated in the left reduction mechanism chamber 15B, and the left axle shaft 39 is accommodated in the left axle chamber 15C.

[0025] Furthermore, a mounting hole 15D is provided in the upper part of the cylindrical part 15A so as to penetrate in the vertical direction (radial direction). An air breather 52 described below is provided in this mounting hole 15D. The lower part of the mounting hole 15D is connected to the uppermost space part 33, and the upper part is open to the outside.

[0026] On the other hand, the right axle tube 16 is symmetrical to the left axle tube 15 in the left-right direction. The right axle tube 16 is formed as a cylindrical body extending from the right end of the differential body 14 to the right so as to reduce in diameter. The left side (differential body 14 side) of the right axle tube 16 is a cylindrical section 16A having an outer diameter dimension equivalent to that of the differential body 14. Inside the right axle tube 16, the inner periphery side of the cylindrical section 16A located on the right side of the differential mechanism chamber 14C becomes a right reduction mechanism chamber 16B, and the right side of the right reduction mechanism chamber 16B becomes a right axle chamber 16C. The right planetary gear reduction mechanism 34 is accommodated in the right reduction mechanism chamber 16B, and the right axle shaft 40 is accommodated in the right axle chamber 16C.

[0027] The cover 17 closes the upper opening of the differential body 14. The cover 17 is made of a rectangular plate, and its periphery is attached to the upper part of the differential body 14 using a plurality of bolts.

[0028] As shown in Fig. 5, the input shaft 18 is rotatably provided within the protruding cylinder 14F of the differential body 14 via a plurality of bearings 19. The input shaft 18 has a flange portion 18A protruding outwardly connected to the propeller shaft 9B. A pinion gear 20 made of a bevel gear is provided on the input shaft 18 on the differential mechanism 21 side.

[0029] As shown in Figures 3 to 5, the differential mechanism 21 is housed in a differential mechanism chamber 14C of the differential body 14. The differential mechanism 21 distributes the rotational force of the output shaft of the transmission 9 to the left and right front wheels 5. The differential mechanism 21 is composed of a cylindrical gear case 22 rotatably supported via bearings 19 on the left and right bulkheads 14A and 14B of the differential body 14, a plurality of pinion gears 23 rotatably provided on a spider 22A fixed to the gear case 22 in a state of extending radially, two side gears 24 meshing with the plurality of pinion gears 23, and a left rotating shaft 25 and a right rotating shaft 26 whose base end side is splined to the side gear 24 and whose tip end side extends leftward and rightward toward a left axle shaft 39 described later.

[0030] The bevel gear 27 is formed as a ring-shaped gear member provided on the outer periphery of the gear case 22. The bevel gear 27 is disposed to the left of the axis (rotation center line) of the input shaft 18 (in a region toward the left in the differential mechanism room 14C). The bevel gear 27 is formed of an annular body that can rotate about the axis XX in the left-right direction, and a tooth portion 27A is formed on one side in the left-right direction, specifically, on the right side that is the input shaft 18 side. That is, the bevel gear 27 has a ring-shaped base portion 27B provided on the left side in the left-right direction, and a tooth portion 27A that is generally ring-shaped and formed on the right surface of the base portion 27B so as to face (face) from the base portion 27B to the right. The right tooth portion 27A of the bevel gear 27 meshes with the pinion gear 20 of the input shaft 18.

[0031] As shown in Figs. 3 and 4, the bevel gear 27 is about half-immersed in the lubricating oil in the differential mechanism chamber 14C. As a result, the bevel gear 27 scoops up the lubricating oil as it rotates, and supplies the lubricating oil to sliding parts, meshing parts, and the like. In this case, many irregularities are formed on the right side of the bevel gear 27 by the teeth 27A. Also, the left side of the bevel gear 27 is a smooth surface without any irregularities. Therefore, the rotating bevel gear 27 scoops up a lot of lubricating oil to the right side by the stirring force of the teeth 27A, and can supply a sufficient amount of lubricating oil to the differential mechanism 21. On the other hand, the left side of the smooth bevel gear 27 scoops up less lubricating oil than the right side of the bevel gear 27.

[0032] The differential mechanism 21 transmits the rotational force from the transmission 9 to the gear case 22 via the input shaft 18 (pinion gear 20) and the bevel gear 27, thereby allowing the left rotating shaft 25 and the right rotating shaft 26 to rotate appropriately via each pinion gear 23 and side gear 24.

[0033] The left planetary gear reduction mechanism 28 is provided in the left reduction mechanism chamber 15B of the left axle tube 15. The left planetary gear reduction mechanism 28 reduces the rotation of the left rotating shaft 25 and transmits it to a left axle shaft 39 described below. The left planetary gear reduction mechanism 28 includes a sun gear 29 integrally formed on the other end side of the left rotating shaft 25, a ring gear 30 located around the sun gear 29 and provided on the inner periphery side of the left axle tube 15, a plurality of planet gears 31 (for example, three planet gears) that mesh with the sun gear 29 and the ring gear 30 (see FIG. 6), and a carrier 32 that rotatably supports the three planet gears 31.

[0034] The ring gear 30 is provided on the inner surface side of the left reduction gear mechanism chamber 15B with the axis XX as the center of rotation. The ring gear 30 is formed as an internal gear having teeth 30A formed on its inner circumferential surface with which the planet gears 31 mesh. As shown in FIG. 6, the outer circumferential surface 30B of the ring gear 30 is inserted into the cylindrical portion 15A of the left axle tube 15.

[0035] A plurality of spaces 33 are formed at intervals in the circumferential direction between the cylindrical portion 15A of the left axle tube 15 and the outer peripheral surface 30B of the ring gear 30. The spaces 33 communicate with the left reduction gear mechanism chamber 15B. Of the plurality of spaces 33, the space 33 located at the top communicates with an air breather 52, which will be described later.

[0036] The right planetary gear reduction mechanism 34 has a symmetrical structure with the left planetary gear reduction mechanism 28 in the left-right direction. Specifically, the right planetary gear reduction mechanism 34 is provided in the right reduction mechanism chamber 16B of the right axle tube 16. The right planetary gear reduction mechanism 34 reduces the rotation of the right rotating shaft 26 and transmits it to a right axle shaft 40, which will be described later. The right planetary gear reduction mechanism 34 includes a sun gear 35 integrally formed on the other end side of the right rotating shaft 26, a ring gear 36 located around the sun gear 35 and provided on the inner periphery side of the right axle tube 16, a plurality of planet gears 37, for example, three planet gears 37 (only one is shown) that mesh with the sun gear 35 and the ring gear 36, and a carrier 38 that rotatably supports the three planet gears 37.

[0037] The ring gear 36, like the left ring gear 30, is provided on the inner surface side of the right reduction gear mechanism chamber 16B with the axis XX as the center of rotation. The ring gear 36 is formed as an internal gear having teeth 36A formed on its inner circumferential surface with which the planet gears 37 mesh. The ring gear 36 has an outer circumferential surface 36B inserted into the cylindrical portion 16A of the right axle tube 16. A plurality of spaces 33 communicating with the right reduction gear mechanism chamber 16B are formed between the cylindrical portion 16A and the outer circumferential surface 36B of the ring gear 36.

[0038] The left axle shaft 39 is provided on the left side of the casing 13, i.e., inside the left axle tube 15. Rotation reduced by the left planetary gear reduction mechanism 28 is transmitted to the left axle shaft 39. The left axle shaft 39 is provided inside the left axle tube 15 so as to be rotatable about the axis line XX as the center of rotation. The base end side of the left axle shaft 39 is spline-coupled to the carrier 32 of the left planetary gear reduction mechanism 28. On the other hand, the tip side of the left axle shaft 39 protrudes from the left axle tube 15, and the left front wheel 5 is attached to the end thereof.

[0039] The right axle shaft 40 has a symmetrical structure with the left axle shaft 39 in the left-right direction. Specifically, the right axle shaft 40 is provided on the right side of the casing 13, i.e., in the right axle tube 16. Rotation reduced by the right planetary gear reduction mechanism 34 is transmitted to the right axle shaft 40. The right axle shaft 40 is provided in the right axle tube 16 so as to be rotatable about the axis XX as the center of rotation. The base end side of the right axle shaft 40 is spline-coupled to the carrier 38 of the right planetary gear reduction mechanism 34. Meanwhile, the tip side of the right axle shaft 40 protrudes from the right axle tube 16, and a right front wheel (not shown) is attached to the end of the right axle shaft 40.

[0040] The left brake mechanism 41 is provided in the left brake chamber 14D of the differential body 14. The left brake mechanism 41 is configured, for example, as a wet-type multi-plate brake mechanism. The left brake mechanism 41 includes a plurality of rotating discs 43 splined to the outer periphery of the left rotating shaft 25 via a hub 42, a non-rotating ring 44 attached to the differential body 14 so as to face the plurality of rotating discs 43 and not to rotate, and a piston 45 that presses the non-rotating ring 44 against the rotating discs 43 by an external hydraulic force.

[0041] The right brake mechanism 46 is provided in the right brake chamber 14E of the differential body 14. The right brake mechanism 46 is configured as a wet-type multi-plate brake mechanism, similar to the left brake mechanism 41. The right brake mechanism 46 includes a plurality of rotating discs 48 splined to the outer periphery of the right rotating shaft 26 via a hub 47, a non-rotating ring 49 attached to the differential body 14 so as to face the plurality of rotating discs 48 and not to rotate, and a piston 50 that presses the non-rotating ring 49 against the rotating discs 48 by an external hydraulic force.

[0042] When a brake pedal (not shown) is depressed, for example, the left brake mechanism 41 and the right brake mechanism 46 move the pistons 45, 50 in the axial direction by hydraulic force. As a result, the left brake mechanism 41 presses the non-rotating ring 44 against the rotating disc 43, and the right brake mechanism 46 presses the non-rotating ring 49 against the rotating disc 48 to generate braking force by friction, thereby applying the brakes to the left and right front wheels 5.

[0043] 3 and 4, lubricating oil 51 is stored in the casing 13. The lubricating oil 51 lubricates and cools the sliding contact parts and meshing parts of the multiple bearings 19, the differential mechanism 21, the left and right planetary gear reduction mechanisms 28 and 34, and the left and right brake mechanisms 41 and 46. The amount of lubricating oil 51 filled, i.e., the position of the liquid level, is set to, for example, about halfway within the casing 13, specifically, at a high position equivalent to the axis line XX.

[0044] Here, the lubricating oil 51 is scooped up by the rotating bevel gear 27, particularly the tooth portion 27A of the bevel gear 27, and is supplied to the lubricating and cooling portions of each part. The bevel gear 27 is disposed to the left of the center in the left-right direction in the differential mechanism chamber 14C of the casing 13. The tooth portion 27A of the bevel gear 27 is formed so that its surface faces the right side of the bevel gear 27. In this case, the lubricating oil 51 is supplied more to the right side of the bevel gear 27 on which the tooth portion 27A is provided in the differential mechanism chamber 14C. Accordingly, in the casing 13, the liquid level of the lubricating oil 51 is higher in the region to the right of the center in the left-right direction than in the region to the left. From another perspective, the scattering (scooped-up amount) of the lubricating oil 51 is less on the left side of the bevel gear 27 in the casing 13 than on the right side, and the liquid level of the lubricating oil 51 is lower.

[0045] Next, the configuration and function of the air breather 52, which is a characteristic feature of this embodiment, will be described in detail.

[0046] The air breather 52 allows air to flow in and out (breathe) between the inside and outside of the casing 13. In this way, the air breather 52 prevents the pressure inside the casing 13 from fluctuating greatly. In this embodiment, the air breather 52 is disposed on the side opposite to the side (or surface) on which the teeth 27A of the bevel gear 27 are formed, in the direction along the rotation axis of the bevel gear 27, that is, on the left side of the differential mechanism 21. Specifically, the air breather 52 is attached to the upper part of the cylindrical portion 15A of the left axle tube 15, that is, to the mounting hole 15D, on the outer circumferential side of the ring gear 30 constituting the left planetary gear reduction mechanism 28.

[0047] Here, the position of the air breather 52 (mounting hole 15D) will be described in detail. First, the air breather 52 is disposed on the outer periphery side of the ring gear 30. Therefore, the ring gear 30 is disposed between the air breather 52 and the lubricating oil 51 stored in the casing 13. This allows the existing ring gear 30 to be used as a baffle plate, so that the lubricating oil 51 that has been scooped up and scattered can be prevented from leaking to the outside through the air breather 52 without providing a separate baffle plate.

[0048] Moreover, the air breather 52 is disposed in the cylindrical portion 15A of the left axle tube 15, which is opposite to the side where the teeth portion 27A of the bevel gear 27 is formed. In this case, the left side of the bevel gear 27 is a position where the scattering (amount of scooped-up) of the lubricating oil 51 is small and the liquid level of the lubricating oil 51 is low. Therefore, even with this configuration, it is possible to prevent the lubricating oil 51 from leaking to the outside through the air breather 52.

[0049] In addition, the air breather 52 is connected to a space 33 that is provided between the cylindrical portion 15A of the left axle tube 15 and the ring gear 30 and that is connected to the left reduction gear mechanism chamber 15B. This allows the air breather 52 to let air in and out of the casing 13 through the space 33.

[0050] Furthermore, when the bevel gear 27 in the casing 13 does not rotate, the height of the liquid level of the lubricating oil 51 in the casing 13 is parallel (horizontal) to the axis XX. On the other hand, when the bevel gear 27 rotates, the teeth 27A of the bevel gear 27 stir the lubricating oil 51, so that the lubricating oil 51 in the casing 13 moves to the right side, which is the side of the teeth 27A. As a result, the liquid level of the lubricating oil 51 in the casing 13 becomes higher on the right side than on the left side. Then, when the bevel gear 27 rotates continuously (runs continuously), the temperature inside the casing 13 rises, and the air pressure rises due to the expansion of the air inside the casing 13.

[0051] In response to this, air breather 52 releases the air inside casing 13 to the outside. Therefore, the air inside casing 13 flows toward air breather 52 on the left side, which can prevent lubricating oil 51 from shifting to the right side. This makes the liquid level of lubricating oil 51 constant inside casing 13, which stabilizes the lubricating efficiency, cooling efficiency, and the like of lubricating oil 51.

[0052] The wheel loader 1 according to this embodiment has the configuration described above, and its operation will now be described.

[0053] First, an operator in the cab 10 operates the transmission 9 for traveling by operating the surrounding levers and pedals (none of which are shown), and the rotational force of the output shaft of this transmission 9 is transmitted to the left and right axle shafts 39, 40 via the propeller shaft 9B, the input shaft 18 of the front axle unit 12, the differential mechanism 21, and the left and right planetary gear reduction mechanisms 28, 34. This allows the left and right front wheels 5 connected to the axle shafts 39, 40 to rotate. Similarly, the left and right rear wheels 4 can be rotated by transmitting the rotation of the output shaft of the transmission 9 from the propeller shaft 9A to the rear axle unit 11.

[0054] In this way, by rotating the front wheels 5 and rear wheels 4, the wheel loader 1 can be driven towards the work site. When turning left or right while driving, each pinion gear 23 of the differential mechanism 21 rotates on its axis and transmits rotational force to each side gear 24. As a result, when turning left, for example, the rotation speed of the left front wheel 5 and rear wheel 4, which are the inner wheels, can be made slower than the rotation speed of the right front wheel and rear wheel, which are the outer wheels, and the difference in rotation speed between the inner front wheel 5 and rear wheel 4 and the outer front wheel and rear wheel allows for a smooth turn.

[0055] During travel, the left and right brake mechanisms 41, 46 can apply braking forces to the left and right axle shafts 39, 40 by operating a brake pedal (not shown), thereby slowing down or stopping the vehicle. On the other hand, when the working implement 6 is operated while travelling, work such as loading earth and sand can be performed.

[0056] The front axle device 12, which transmits the rotational force of the output shaft of the transmission 9 to the front wheels 5, and the rear axle device 11, which transmits the rotational force to the rear wheels 4, experience a temperature rise due to frictional heat of the brake mechanisms 41, 46, etc., and the air pressure inside the casing 13 rises. When the air pressure inside the casing 13 rises, a load is applied to the sealing members, etc.

[0057] Therefore, for example, the front axle device 12 can suppress an increase in air pressure within the casing 13 by discharging the air within the casing 13 to the outside through the air breather 52.

[0058] Here, if the lubricating oil 51 scooped up by the bevel gear 27 splashes inside the casing 13, there is a risk that the splashed lubricating oil 51 will leak to the outside through the air breather 52. Therefore, it is conceivable to provide a new baffle plate between the bevel gear 27 and the air breather 52. However, in order to provide a baffle plate, a dedicated space must be secured, which increases the size of the system. In addition, the cost increases due to the increase in the number of parts and the number of installation steps.

[0059] According to this embodiment, however, the air breather 52 that allows air to flow between the inside and outside of the casing 13 is disposed in the left reduction gear mechanism chamber 15B that is provided in communication with the differential mechanism chamber 14C.

[0060] Therefore, since the air breather 52 is disposed in the left reduction gear mechanism chamber 15B separated in the left-right direction from the differential mechanism chamber 14C, it is possible to prevent the lubricating oil 51 scooped up in the differential mechanism chamber 14C from leaking out to the outside through the air breather 52. As a result, in this embodiment, it is possible to promote the miniaturization of the front axle unit 12 and the rear axle unit 11 and reduce the costs.

[0061] The differential mechanism 21 is provided with a bevel gear 27 that is rotatable about a left-right axis XX and has teeth 27A formed toward the right in the left-right direction. The air breather 52 is disposed on the opposite side of the casing 13 in the left-right direction to the right side to which the teeth 27A of the bevel gear 27 faces. Therefore, the air breather 52 can be disposed in a position where the lubricating oil 51 scooped up to the right by the teeth 27A of the bevel gear 27 is unlikely to splash on the air breather 52. This also makes it possible to prevent the lubricating oil 51 from leaking to the outside through the air breather 52.

[0062] The left planetary gear reduction mechanism 28 is provided on the inner surface side of the left reduction mechanism chamber 15B and has a ring gear 30 having a toothed portion 30A formed on its inner circumferential surface with which the planet gear 31 meshes, and the right planetary gear reduction mechanism 34 is provided on the inner surface side of the right reduction mechanism chamber 16B and has a ring gear 36 having a toothed portion 36A formed on its inner circumferential surface with which the planet gear 37 meshes. In addition, the air breather 52 is disposed on the outer circumferential side of the ring gear 30 in the left planetary gear reduction mechanism 28 and on the upper part of the casing 13. As a result, the air breather 52 and the lubricating oil 51 stored in the casing 13 can be shielded by the existing ring gear 30, so that the lubricating oil 51 can be prevented from leaking to the outside through the air breather 52.

[0063] Furthermore, the air breather 52 communicates with a space 33 provided between the cylindrical portion 15A of the left axle tube 15 and the ring gear 30, the space 33 being in communication with the left reduction gear mechanism chamber 15B. More specifically, the air breather 52 is attached to a mounting hole 15D perpendicular to the space 33 extending in the direction of the axis XX. As a result, the lubricating oil 51 that has entered the space 33 is unlikely to enter the mounting hole 15D, and the air breather 52 can let air in and out of the casing 13 while preventing leakage of the lubricating oil 51.

[0064] In the embodiment, the air breather 52 is attached to the upper part of the cylindrical portion 15A of the left axle tube 15, which is the side opposite to the tooth portion 27A of the bevel gear 27 of the differential mechanism 21. However, the present invention is not limited to this, and the air breather 52 may be attached to the upper part of the cylindrical portion 16A of the right axle tube 16. Also, the air breather 52 may be attached to both the left axle tube 15 and the right axle tube 16.

[0065] In the embodiment, a configuration is shown in which the rotational force of the engine 7 is transmitted to the rear axle device 11 and the front axle device 12 via the torque converter 8 and the transmission 9. However, the present invention is not limited to this. For example, a hydraulic pump is driven by the engine, and a hydraulic motor is driven by pressure oil discharged from the hydraulic pump. Then, the rotational force of the hydraulic motor may be transmitted to the rear axle device and the front axle device via a reduction gear mechanism.

[0066] In the embodiment, the wheel loader 1 has been described as an example of a vehicle to which the rear axle unit 11 and the front axle unit 12 are applied. However, the present invention is not limited to this, and can be widely applied to traveling axle units of other wheeled construction machines, such as wheeled hydraulic excavators, large mining dump trucks, and tractors. [Explanation of symbols]

[0067] 7 Engine (power source) 11 Rear axle device (driving axle device) 12 Front axle device (driving axle device) 13 Casing 14 Differential body 14C Differential mechanism room 15 Left axle tube 15B Left reduction mechanism room 16 Right axle tube 16B Right reduction mechanism room 21 Differential mechanism 25 Left rotation axis 26 Right rotation axis 27 Bevel gear 27A,30A,36A Teeth 28 Left planetary gear reduction mechanism 30,36 Ring gear 33 Space section 34 Right planetary gear reduction mechanism 39 Left axle shaft 40 Right axle shaft 51 Lubricating oil 52 Air Breather XX axis (rotation axis)

Claims

1. a casing having a hollow structure extending in the left-right direction and including a differential mechanism chamber and speed reduction mechanism chambers provided on both the left and right sides of the differential mechanism chamber and communicating with the differential mechanism chamber; a differential mechanism provided in the differential mechanism chamber of the casing and configured to distribute a rotational force of a drive source to left and right rotation shafts; left and right planetary gear reduction mechanisms provided in the left and right reduction mechanism chambers of the casing and configured to reduce the rotation speeds of the left and right rotary shafts; left and right axle shafts provided on both left and right sides in the casing, to which rotation reduced by the left and right planetary gear reduction mechanisms is transmitted; an air breather for letting air in and out between the inside and the outside of the casing; In a traveling axle device comprising: A traveling axle device characterized in that the air breather is disposed in either the left or right reduction mechanism chamber.

2. The traveling axle device according to claim 1, the differential mechanism is rotatable about an axis in the left-right direction and includes a bevel gear having teeth formed toward one side in the left-right direction; A traveling axle device characterized in that the air breather is arranged on the opposite side of the casing in the left-right direction to the side to which the teeth portion of the bevel gear faces.

3. The traveling axle device according to claim 1, Each of the left and right planetary gear reduction mechanisms has a ring gear that is provided on an inner surface side of the respective reduction mechanism chamber and has teeth formed on an inner circumferential surface thereof with which a planet gear meshes, A traveling axle device characterized in that the air breather is arranged on the upper part of the casing on the outer circumferential side of the ring gear in either the left or right planetary gear reduction mechanism.

4. The traveling axle device according to claim 3, A space portion communicating with the reduction mechanism chamber is formed between the casing and the ring gear, A traveling axle device, wherein the air breather is in communication with the space.

Images