阅读说明：本技术 车辆用车轴装置 (Vehicle axle device ) 是由 大西智裕 于 2019-08-05 设计创作，主要内容包括：在差速器箱(23)内设有多片旋转盘(38)和多片非旋转盘(39),该多片旋转盘花键结合于右侧齿轮(35)的外周侧,该多片非旋转盘配置于各旋转盘(38)之间,相对于差速器箱(23)无法旋转且能够沿左右方向移动。在位于右侧齿轮(35)侧的右护圈(41)与非旋转盘(39)之间,设有将非旋转盘(39)朝向旋转盘(38)按压的耐压环(43)。在右护圈(41)的与耐压环(43)在左右方向上相对的位置设有活塞收容部(41D),在该活塞收容部(41D)设有活塞(46),该活塞通过利用液压移位而经由耐压环(43)将非旋转盘(39)按压于旋转盘(38)。(A plurality of rotating disks (38) spline-coupled to the outer peripheral side of the right gear (35), and a plurality of non-rotating disks (39) disposed between the rotating disks (38) and capable of moving in the left-right direction while being unrotatable relative to the differential case (23) are provided in the differential case (23). A pressure ring (43) for pressing the non-rotating disk (39) against the rotating disk (38) is provided between the right retainer (41) located on the right side gear (35) side and the non-rotating disk (39). A piston housing section (41D) is provided in a position of the right retainer (41) that faces the pressure ring (43) in the left-right direction, and a piston (46) that presses the non-rotating disk (39) against the rotating disk (38) via the pressure ring (43) by hydraulic displacement is provided in the piston housing section (41D).)

1. A vehicular axle device comprising: left and right axles on which left and right wheels are mounted, respectively; a hollow differential main body provided between left and right axle tubes that accommodate the left and right axles, and having through holes that penetrate in the left-right direction on both sides in the left-right direction; and a differential mechanism provided between the left and right bulkheads of the differential body and transmitting a rotational force of a drive source to the left and right axles,

the differential mechanism includes:

a differential case rotatably supported via bearings by left and right cages attached to the through holes of the left and right partition walls, respectively, and rotated by the drive source,

a plurality of pinion gears provided in the differential case and rotating together with the differential case;

left and right side gears provided in the differential case and engaged with the respective pinions; and

left and right propeller shafts connected to the side gears and transmitting rotation of the differential case to the left and right axles,

the vehicular axle device is characterized in that,

a plurality of rotating disks spline-coupled to an outer peripheral side of one of the left and right side gears, and a plurality of non-rotating disks disposed between the plurality of rotating disks and movable in the left-right direction with respect to the differential case,

a pressure ring for pressing the non-rotating disk toward the rotating disk is provided between one of the left and right cages located on the one gear side and the non-rotating disk,

a piston housing portion is provided at a position of the one retainer which is opposed to the pressure ring in the left-right direction,

the piston housing portion of the one retainer is provided with a piston that is displaced by hydraulic pressure to press the non-rotating disk against the rotating disk via the pressure ring, thereby coupling the left and right transmission shafts.

2. The vehicular axle device according to claim 1,

a hydraulic chamber to which hydraulic oil for pressing the piston is supplied is formed between the piston and the piston housing portion of the one retainer,

an oil passage for connecting a hydraulic pressure source and the hydraulic pressure chamber is formed in the one partition wall and the one retainer.

3. The vehicular axle device according to claim 1,

the differential case includes:

a1 st differential case rotatably supported by the other of the left and right cages, the differential case being provided with a ring gear to which a rotational force generated by the drive source is transmitted on an outer circumferential side thereof, and provided with the other of the left and right side gears on an inner circumferential side thereof;

a2 nd differential case attached to the 1 st differential case and provided with the one side gear on an inner peripheral side; and

a 3 rd differential case attached to the 2 nd differential case on a side opposite to the 1 st differential case in a left-right direction, and rotatably supported by the one retainer,

the rotating disks and the non-rotating disks are disposed between the inner peripheral side of the 2 nd differential case and the one-side gear,

the piston presses the non-rotating disk via the pressure ring inserted through the 3 rd differential case.

4. A vehicular axle device according to claim 3,

a pressing plate is arranged between the non-rotating disk and the pressure ring, and the pressing plate presses the non-rotating disk when the piston works and the pressure ring moves towards the non-rotating disk,

a pin which is inserted into the No. 3 differential case and the pressing plate is arranged between the No. 2 differential case and the pressure ring,

a return spring is provided between the 2 nd differential case and the pressing plate, the return spring being disposed on an outer peripheral side of the pin and urging the pressing plate toward the piston.

Technical Field

The present invention relates to a vehicular axle device suitably used for a wheel type construction machine such as a wheel loader and a wheel type hydraulic excavator.

Background

Generally, as a typical example of a wheel type construction machine, for example, a wheel loader is known. In this wheel loader, a front body is coupled to a front side of a rear body so as to be swingable in the left-right direction, and a working device including an arm, a bucket, and the like is mounted on the front body. An engine, a torque converter, a transmission, a hydraulic pump, and the like are mounted as drive sources on a rear vehicle body of the wheel loader. The power of the engine is transmitted to the transmission via the torque converter.

An axle device for rotationally driving the left and right wheels is mounted on each of the front vehicle body and the rear vehicle body. The axle device is connected to an output shaft of the transmission via a propeller shaft, and transmits the rotational force of the engine to right and left wheels. The axle device includes left and right axles, a hollow differential main body, and a differential mechanism. The differential main body is provided between left and right axle tubes that accommodate left and right axles. The differential mechanism is provided in the differential main body and distributes the rotational force of the engine to the left and right wheels. The left and right axle tubes of the front axle device are respectively provided with a mounting part. The front axle device is attached to the front vehicle body via these left and right attachment portions. On the other hand, the rear axle device is attached to the rear vehicle body via an axle carrier.

When the wheel loader is traveling on a sandy or muddy road, for example, when the state of the road surface with which the left wheel is in contact is different from the state of the road surface with which the right wheel is in contact, one of the left and right wheels may spin due to the differential mechanism. Therefore, a differential mechanism with differential limitation (limited slip differential mechanism) is known. The differential mechanism with differential limitation temporarily locks the differential mechanism according to the situation. This allows the rotational force of the engine to be transmitted to the left and right wheels without causing idle rotation.

The differential mechanism with differential regulation includes a differential case rotated by an engine, a pinion gear provided in the differential case, left and right side gears, left and right drive shafts, a non-rotating disk, and a rotating disk. The left and right side gears mesh with the pinion gears in the differential case. The left and right propeller shafts are connected to the left and right side gears, and transmit rotation of the differential case to the axles. The non-rotating disk is disposed in the differential case in a non-rotating state with respect to the differential case. The rotating disk is disposed in the differential case so as to overlap the non-rotating disk in the axial direction, and rotates integrally with the left and right side gears. The hydraulic clutch type differential mechanism with differential limitation includes a piston that moves in the axial direction by being supplied with a hydraulic pressure. The piston presses the non-rotating disk into frictional contact with the rotating disk. Thus, when the torque difference between the left and right axles is equal to or less than the torque capacity of the clutch, the differential mechanism is in the locked state (differential locked state). As a result, the left and right side gears rotate integrally with the differential case, and the left and right propeller shafts are coupled to each other. This transmits torque to the left and right axles (see patent document 1).

Disclosure of Invention

A partition wall is provided inside a differential main body constituting the axle device, and a gear chamber for housing the differential mechanism is defined by the partition wall. The differential main body has two types of one-piece structure in which a portion forming the gear chamber is formed integrally with the partition wall, and two-piece structure in which a portion forming the gear chamber is separated from the partition wall. The differential main body having the one-piece structure can reduce the number of components and the number of assembly steps, as compared with the differential main body having the two-piece structure, and can simplify the axle device. The axle device of patent document 1 has a differential main body having a two-piece structure, and a piston is provided in a piston housing portion provided on a face of a partition wall on the gear chamber side.

However, in the case of the differential main body having the one-piece structure, the space in the gear chamber is narrowed by the presence of the partition walls on the left and right sides of the gear chamber, and the machining work in the gear chamber is also difficult. Therefore, the differential main body having the one-piece structure has a problem that it is difficult to form the piston housing portion on the face of the partition wall on the gear chamber side, while the number of components and the number of assembly steps can be reduced.

The present invention has been made in view of the above-described problems of the conventional art, and an object of the present invention is to provide a vehicular axle device capable of simplifying the structure of a differential main body.

The present invention is applied to a vehicle axle device including: left and right axles on which left and right wheels are mounted, respectively; a hollow differential main body provided between left and right axle tubes that accommodate the left and right axles, and having through holes that penetrate in the left-right direction on both sides in the left-right direction; and a differential mechanism provided between the left and right bulkheads of the differential body and transmitting a rotational force of a drive source to the left and right axles, the differential mechanism including: a differential case rotatably supported via bearings by left and right cages attached to the through holes of the left and right partition walls, respectively, and rotated by the drive source, and a plurality of pinion gears provided in the differential case and rotated together with the differential case; left and right side gears provided in the differential case and engaged with the respective pinions; and left and right propeller shafts connected to the side gears and transmitting rotation of the differential case to the left and right axles.

The invention is characterized in that a plurality of rotating disks and a plurality of non-rotating disks are arranged in the differential case, the plurality of rotary disks are spline-coupled to the outer peripheral side of one of the left and right side gears, the non-rotating disks are disposed between the rotating disks and are non-rotatable with respect to the differential case and movable in the left-right direction, a pressure ring for pressing the non-rotating disk toward the rotating disk is provided between one of the left and right cages located on the one gear side and the non-rotating disk, a piston housing portion is provided in a position of the one retainer that is opposed to the pressure ring in the left-right direction, a piston is provided in the piston housing portion of the one retainer, the piston presses the non-rotating disk against the rotating disk via the pressure ring by hydraulic displacement, thereby coupling the left and right drive shafts.

According to the present invention, the piston housing portion is provided in one of the left and right cages, and the piston can be provided in the piston housing portion provided in the one cage. Thus, the piston can be assembled to the differential mechanism housed in the differential main body only by attaching one of the retainers to the through-hole of the partition wall. Therefore, the structure of the differential main body can be simplified as compared with a case where, for example, the piston housing portion is formed in the partition wall of the differential main body.

Drawings

Fig. 1 is a front view showing a wheel loader including a vehicular axle device according to an embodiment of the present invention.

Fig. 2 is an enlarged external perspective view of the front axle device in fig. 1 from the front.

Fig. 3 is a cross-sectional view showing the internal structure of the front axle device.

Fig. 4 is a main-part enlarged sectional view showing the differential main body, the differential mechanism, and the like in fig. 3 in an enlarged manner.

Fig. 5 is an exploded perspective view showing main components of the differential mechanism.

Fig. 6 is a perspective view showing the 1 st differential case as a single body.

Fig. 7 is a perspective view showing the 2 nd differential case as a single body.

Fig. 8 is a perspective view showing the 3 rd differential case as a single body.

Fig. 9 is a perspective view showing the non-rotating disk in a single body.

Fig. 10 is a perspective view showing the pressing plate alone.

Fig. 11 is a perspective view showing a pressure ring (compression ring) in a single body.

Fig. 12 is a side view showing a state where the piston is attached to the right shroud.

Fig. 13 is an enlarged cross-sectional view of a main portion of the right retainer, the piston, the hydraulic chamber, the oil passage, and the like shown in fig. 4.

Fig. 14 is a front view showing a state in which a right retainer is attached to a right partition wall of the differential main body.

Detailed Description

Hereinafter, an embodiment of a vehicle axle device according to the present invention will be described in detail with reference to fig. 1 to 14, taking a case where the vehicle axle device is mounted on a wheel loader as an example.

In fig. 1, a wheel loader 1 is configured to include a rear body 2, a front body 3, rear wheels 4, front wheels 5, a working device 6 provided on the front side of the front body 3, and axle devices 11 and 12 described below. The front body 3 is connected to the front side of the rear body 2 so as to be swingable in the left-right direction. The rear wheels 4 are provided on both sides of the rear body 2 in the left-right direction, and the front wheels 5 are provided on both sides of the front body 3 in the left-right direction.

Here, an engine 7, a torque converter 8, a transmission 9, a hydraulic pump (not shown), and the like are mounted as drive sources on the rear vehicle body 2. The transmission 9 is connected to a rear axle device 11 via a propeller shaft 9A extending in the front-rear direction, and is connected to a front axle device 12 via a propeller shaft 9B. An operator cab 10 on which an operator rides is provided above the rear body 2.

The rear axle device 11 is provided 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 both ends in the left-right direction.

The front axle device 12 is provided below the front vehicle body 3. The front axle device 12 is formed to extend in the left-right direction like the rear axle device 11, and front wheels 5 are attached to both ends in the left-right direction.

Here, the rear axle device 11 and the front axle device 12 are configured similarly except that the connecting positions of the propeller shafts 9A and 9B are different. Therefore, in the present embodiment, the structure of the front axle device 12 will be described in detail, and the structure of the rear axle device 11 will not be described.

The front axle device 12 rotationally drives the left and right front wheels 5 by being connected to the propeller shaft 9B. As shown in fig. 2 and 3, the front axle device 12 includes a housing 13, left and right axles 19L and 19R, a differential mechanism 20, left and right planetary gear reduction mechanisms 51L and 51R, left and right brake mechanisms 55L and 55R, and the like.

The housing 13 constitutes a housing of the front axle device 12. The case 13 includes a hollow differential body (differential body)14 located in a middle portion in the left-right direction, and left and right axle tubes (axletube)15L, 15R located on both sides of the differential body 14 in the left-right direction. The differential mechanism 20 and the left and right brake mechanisms 55L and 55R are housed inside the differential main body 14. Axles 19L and 19R are rotatably supported in the left and right axle tubes 15L and 15R, respectively. Front wheels 5 are mounted on the tip ends of the left and right axles 19L, 19R, respectively.

As shown in fig. 3 and 4, the differential main body 14 is formed of a cylindrical tube body centered on an axis a-a extending in the left-right direction (axial direction), and has a one-piece structure in which a left partition wall 14B and a right partition wall 14C, which will be described later, are integrally formed. Both ends of the differential main body 14 in the left-right direction are open ends 14A, respectively. Left and right partition walls 14B, 14C are integrally provided on the left and right sides of the differential main body 14, respectively. The left and right partition walls 14B, 14C extend radially inward from the inner circumferential surface of the portion further toward the inside than the opening end 14A. Through-holes 14D having a smaller diameter than the opening end 14A are formed in the left and right partition walls 14B and 14C, respectively, so as to penetrate in the left-right direction (axial direction).

The inside of the differential main body 14 is partitioned into a gear chamber 14E located between the left and right partition walls 14B, 14C, and left and right brake chambers 14F, 14G disposed on the left and right sides across the gear chamber 14E. The differential mechanism 20 is housed in the gear chamber 14E, the brake mechanism 55L is housed in the left brake chamber 14F, and the brake mechanism 55R is housed in the right brake chamber 14G. Further, a projecting cylinder 14H projecting toward the transmission 9 is provided on the rear side (the rear axle device 11 side) of the differential main body 14. The projecting cylinder 14H opens into the gear chamber 14E, and an input shaft 17 described later is rotatably supported in the projecting cylinder 14H.

The proximal end sides of the left and right axle tubes 15L, 15R are short cylindrical portions 15A having a diameter equal to both ends of the differential main body 14 in the left-right direction. The inside of the left and right cylindrical portions 15A is a reduction gear chamber 15B, and planetary gear reduction mechanisms 51L and 51R described later are housed in the left and right reduction gear chambers 15B. The tip ends of the left and right shaft tubes 15L and 15R are respectively shaped like a prism and extend outward in the left-right direction from the cylindrical portion 15A. The cylindrical portions 15A of the left and right axle tubes 15L, 15R are attached to the open end 14A of the differential main body 14 by a plurality of bolts 16. The left and right axle tubes 15L, 15R extend from the differential main body 14 while reducing in diameter on both sides in the left-right direction.

On the upper surface sides of the left and right shaft tubes 15L, 15R, a rectangular attachment portion 15C is provided adjacent to the cylindrical portion 15A. These left and right mounting portions 15C are mounted to the front body 3 of the wheel loader 1. That is, the front axle device 12 is an interior type (inner type) axle device in which the differential mechanism 20, the left and right planetary gear reduction mechanisms 51L, 51R, and the left and right brake mechanisms 55L, 55R are provided between the attachment portions 15C of the left and right axle tubes 15L, 15R. The rear axle device 11 is attached to the rear vehicle body 2 via an axle carrier (not shown).

The input shaft 17 is rotatably provided in the protruding cylinder 14H of the differential main body 14 via 2 bearings 18. A connecting flange 17A is provided at one end of the input shaft 17 protruding outside the protruding cylinder 14H, and the connecting flange 17A is connected to the propeller shaft 9B. A drive pinion 17B formed of a bevel gear is formed on the other end of the input shaft 17 projecting into the gear chamber 14E of the differential main body 14, and the drive pinion 17B meshes with a ring gear (ring gear)30 described later.

The left axle 19L extends axially in the left axle tube 15L, and the right axle 19R extends axially in the right axle tube 15R. These left and right axles 19L, 19R are disposed on the axis A-A. The base end side of the axle 19L is spline-coupled to a carrier 54 of a planetary gear reduction mechanism 51L described later. The axle 19L projects from the axle tube 15L on the tip end side thereof, and the front wheel 5 is attached to the tip end portion thereof. The axle 19R has a base end spline coupled to a carrier 54 of a planetary gear reduction mechanism 51R described later. The axle 19R projects from the axle tube 15R on the tip end side thereof, and the front wheel 5 is attached to the tip end portion thereof.

Next, the differential mechanism 20 of the present embodiment will be described.

The differential mechanism 20 is provided in the gear chamber 14E of the differential main body 14. The differential mechanism 20 distributes and transmits the driving force (rotational force) of the engine 7 as a driving source to the left and right front wheels 5 via the left and right axles 19L, 19R. Here, the differential mechanism 20 is constituted by a differential mechanism with differential restriction (limited slip differential mechanism) that temporarily becomes a locked state (differential locked state) depending on the situation. The differential mechanism 20 includes a differential case 23, a ring gear 30, a plurality of pinion gears 33, left and right side gears 34, 35, left and right drive shafts 36, 37, a plurality of rotating disks 38, a plurality of non-rotating disks 39, a piston 46, and the like, which will be described later.

A cylindrical left retainer 21 having a flange portion 21A is attached to a through hole 14D of a left partition wall 14B constituting the differential main body 14, and the flange portion 21A of the left retainer 21 is fixed to the left partition wall 14B by a bolt 22. A right retainer 41, which will be described later, is attached to a through hole 14D of the right partition wall 14C constituting the differential main body 14, and the right retainer 41 is fixed to the right partition wall 14C by a bolt 22.

The differential case 23 is provided in the gear chamber 14E of the differential main body 14. The differential case 23 is supported rotatably on the axis a-a by the left and right cages 21 and 41, respectively, via bearings 24. The differential case 23 is a member constituting a housing of the differential mechanism 20, and is composed of a1 st differential case 25, a2 nd differential case 26, and a 3 rd differential case 27.

As shown in fig. 4 and 6, the 1 st differential case 25 is a belt-differential cylindrical body having a small-diameter cylindrical portion 25A and a large-diameter cylindrical portion 25B, and a shaft insertion hole 25C penetrating in the left-right direction is formed in the center portion. A disc-shaped flange 25D having a large diameter is provided between the small-diameter cylindrical portion 25A and the large-diameter cylindrical portion 25B. The small-diameter cylindrical portion 25A is supported by the left retainer 21 via the bearing 24. A plurality of bolt insertion holes 25E are formed in the flange portion 25D over the entire circumference. A plurality of screw holes (female screw holes) 25G are formed in the axial end surface 25F of the large diameter cylindrical portion 25B over the entire circumference. Further, 4 semicircular recesses 25H are formed at 90 ° angular intervals on the axial end surface 25F of the large-diameter cylindrical portion 25B.

As shown in fig. 4 and 7, the 2 nd differential case 26 is formed as a hollow cylindrical belt step having a small diameter cylindrical portion 26A and a large diameter cylindrical portion 26B. The small-diameter cylindrical portion 26A has an outer diameter and a thickness equal to those of the large-diameter cylindrical portion 25B of the 1 st differential case 25. A plurality of bolt insertion holes 26C penetrating in the left-right direction are formed in the small diameter cylindrical portion 26A over the entire circumference. The bolt insertion holes 26C correspond to the screw holes 25G of the 1 st differential case 25. On an axial end surface 26D of the small-diameter cylindrical portion 26A, 4 semicircular recesses 26E are formed at angular intervals of 90 °. Each concave portion 26E corresponds to each concave portion 25H of the 1 st differential case 25. A plurality of screw holes 26G are formed in the axial end surface 26F of the large diameter cylindrical portion 26B over the entire circumference. Further, 4 rectangular recesses 26H are formed in the axial end surface 26F at angular intervals of 90 °. A screw hole 26J is formed in the bottom of each recess 26H. A plurality of (for example, 8) grooves 26L having a semicircular shape in cross section extending in the axial direction are formed at regular angular intervals on the inner peripheral surface 26K of the large-diameter cylindrical portion 26B. The projections 39A of the non-rotating disk 39 described later are engaged with the respective recesses 26L.

The 3 rd differential case 27 is attached to the 2 nd differential case 26 on the side opposite to the 1 st differential case 25 in the left-right direction. As shown in fig. 4 and 8, the 3 rd differential case 27 includes a cylindrical portion 27A and a disc-shaped flange portion 27B having a larger diameter than the cylindrical portion 27A. The flange portion 27B has an outer diameter equal to the large-diameter cylindrical portion 26B of the 2 nd differential case 26. A shaft insertion hole 27C that penetrates in the axial direction is formed in the center of the 3 rd differential case 27. The cylindrical portion 27A is supported by the right retainer 41 via the bearing 24. The flange portion 27B has a plurality of bolt insertion holes 27D formed in the entire circumference. The bolt insertion holes 27D correspond to the screw holes 26G of the 2 nd differential case 26. Further, 4 pin insertion holes 27E having a smaller diameter than the bolt insertion holes 27D are formed in the flange portion 27B at angular intervals of 90 °. The pin insertion holes 27E correspond to the screw holes 26J of the 2 nd differential case 26. A plurality of (for example, 8) rectangular holes 27F penetrating in the axial direction are formed in the flange portion 27B at positions radially inward of the respective bolt insertion holes 27D. Each rectangular projection 43D of the pressure ring 43 described later is inserted into each rectangular hole 27F so as to be movable.

Bolts 28 are inserted into the respective bolt insertion holes 26C of the 2 nd differential case 26. The bolts 28 are screwed into the screw holes 25G of the 1 st differential case 25. Thereby, the 2 nd differential case 26 is fixed with respect to the 1 st differential case 25. At this time, the axial end face 25F of the 1 st differential case 25 abuts against the axial end face 26D of the 2 nd differential case 26 (small diameter cylindrical portion 26A). Each shaft 32A of a spider shaft (spider)32 described later is locked between the recess 25H of the 1 st differential case 25 and the recess 26E of the 2 nd differential case 26. Bolts 29 are inserted into the respective bolt insertion holes 27D of the 3 rd differential case 27. The bolts 29 are screwed into the screw holes 26G of the 2 nd differential case 26. Thereby, the 3 rd differential case 27 is fixed with respect to the 2 nd differential case 26. Thus, the differential case 23 including the 1 st, 2 nd, and 3 rd differential cases 25, 26, and 27 is assembled. Inside the differential case 23, a cross 32, a plurality of pinion gears 33, and left and right side gears 34, 35 are disposed.

The ring gear 30 is mounted to the differential case 23 in the gear chamber 14E of the differential main body 14. The ring gear 30 is constituted by an annular bevel gear. The ring gear 30 is fixed to the flange portion 25D of the 1 st differential case 25 by a plurality of bolts 31 inserted into the respective bolt insertion holes 25E of the 1 st differential case 25. The ring gear 30 meshes with the drive pinion 17B of the input shaft 17. Therefore, the rotation of the engine 7 is transmitted to the input shaft 17 via the transmission 9, and the differential case 23 rotates by the engagement of the drive pinion 17B with the ring gear 30.

The cross 32 is provided in the differential case 23. As shown in fig. 5, cross 32 has 4 shafts 32A combined in a cross shape at angular intervals of 90 °. The tip end side of each shaft 32A is sandwiched between the recess 25H of the 1 st differential case 25 and the recess 26E of the 2 nd differential case 26 constituting the differential case 23. The cross 32 rotates integrally with the differential case 23.

Each of the plurality of (4) pinions 33 is rotatably supported by 4 shafts 32A provided on the cross 32. Each pinion 33 is formed of a bevel gear and is integrated by a spider 32. The pinions 33 mesh with a left side gear 34 and a right side gear 35 in the differential case 23.

The left and right gears 34 and 35 are provided in the differential case 23, respectively. These left and right side gears 34, 35 are paired in the left-right direction with the cross 32 interposed therebetween. In the present embodiment, the right side gear 35 constitutes one of the left and right side gears. The left and right side gears 34, 35 are each formed by a bevel gear, and mesh with the pinion gears 33 supported by the spider 32. A thrust plate (throstplate) 34A that reduces wear of the 1 st differential case 25 is provided between the left side gear 34 and the 1 st differential case 25. A thrust plate 35A that reduces wear of the 3 rd differential case 27 is provided between the right-hand gear 35 and the 3 rd differential case 27. Further, a shaft spline portion 35B is formed on the outer peripheral surface of the right gear 35.

The left drive shaft 36 is connected to the left gear 34, and the right drive shaft 37 is connected to the right gear 35. The left and right propeller shafts 36, 37 are arranged in pairs on the axis A-A. The left propeller shaft 36 transmits the rotation of the differential case 23 to the axle 19L via the planetary gear reduction mechanism 51L. The right propeller shaft 37 transmits the rotation of the differential case 23 to the axle 19R via the planetary gear reduction mechanism 51R.

The base end side of the left transmission shaft 36 is spline-coupled to the inner peripheral side of the left gear 34. The tip end side of the left propeller shaft 36 extends through the left partition wall 14B of the differential main body 14 into the shaft tube 15L. A sun gear 36A constituting a planetary gear reduction mechanism 51L is integrally formed at the tip end of the left propeller shaft 36. On the other hand, the base end side of the right propeller shaft 37 is spline-coupled to the inner peripheral side of the right gear 35. The tip end side of the right propeller shaft 37 extends through the right bulkhead 14C of the differential main body 14 into the shaft tube 15R. A sun gear 37A constituting a planetary gear reduction mechanism 51R is integrally formed at the tip end of the right transmission shaft 37.

Between the inner peripheral surface 26K of the 2 nd differential case 26 constituting the differential case 23 and the shaft spline portion 35B of the right side gear 35, a plurality of rotary disks 38 and a plurality of non-rotary disks 39 are provided. The rotating disks 38 and the non-rotating disks 39 are each formed of an annular plate body and are arranged so as to overlap each other alternately in the axial direction.

The inner peripheral side of each rotary disk 38 is spline-coupled to the shaft spline portion 35B of the right gear 35. Therefore, each rotary disk 38 is rotatable together with the right side gear 35 relative to the differential case 23 while being movable in the axial direction of the right side gear 35. As shown in fig. 9, each non-rotating disk 39 has a plurality of (for example, 8) protrusions 39A over the entire circumference of the outer circumferential side thereof. The projections 39A engage with the recesses 26L formed in the inner peripheral surface 26K of the 2 nd differential case 26. Therefore, each non-rotating disk 39 is held in a state in which it is movable in the axial direction of the differential case 23 and is not rotatable relative to the differential case 23.

The pressing plate 40 is located in the differential case 23 and is provided between the 3 rd differential case 27 and the non-rotating disk 39. As shown in fig. 10, the pressing plate 40 is formed of an annular plate body, and 4 protruding portions 40A protruding outward in the radial direction are provided on the outer peripheral side of the pressing plate 40 at angular intervals of 90 °. These 4 projections 40A engage with the respective recesses 26H of the 2 nd differential case 26. Therefore, the pressing plate 40 rotates integrally with the differential case 23 while being movable in the axial direction along the concave portions 26H. Each projection 40A of the pressing plate 40 is formed with a pin insertion hole 40B. The pin insertion holes 40B correspond to screw holes 26J formed in the recesses 26H of the 2 nd differential case 26.

The right retainer 41 is attached to a through hole 14D of a right partition wall 14C constituting the differential main body 14. The right retainer 41 constitutes one retainer located on the right gear 35 side. As shown in fig. 12 to 14, the right retainer 41 is formed in a stepped cylindrical shape having a cylindrical portion 41A fitted in the through hole 14D and a flange portion 41B having a larger diameter than the cylindrical portion 41A. As shown in fig. 14, a plurality of bolt insertion holes 41C are formed in the entire circumferential range of the flange portion 41B of the right retainer 41. Bolts 22 are inserted into the bolt insertion holes 41C, and the bolts 22 are screwed into the screw holes 14J provided in the right partition wall 14C of the differential main body 14. Thus, the right retainer 41 is attached to the right bulkhead 14C with the cylindrical portion 41A fitted in the through hole 14D.

A piston housing portion 41D having a 2-step portion is formed in a portion of the right retainer 41 that faces the non-rotating disk 39 in the axial direction. The piston housing portion 41D is formed by cutting the outer peripheral surface of the cylindrical portion 41A over the entire circumference. The piston housing portion 41D includes a large diameter stepped portion 41E adjacent to the end surface of the cylindrical portion 41A, and a small diameter stepped portion 41F adjacent to the end surface of the large diameter stepped portion 41E. A piston 46 described later is mounted in the piston housing portion 41D. O-rings 42 are attached to the outer peripheral surfaces of the large diameter stepped portion 41E and the small diameter stepped portion 41F, respectively. The O-ring 42 seals the space between the piston 46 and the right retainer 41 (piston housing portion 41D) in a liquid-tight manner. Further, a retainer-side oil passage 49B, which will be described later, opens to an end surface 41G of the piston housing portion 41D located at a boundary between the large-diameter stepped portion 41E and the small-diameter stepped portion 41F. A nut 41H is screwed to the inner peripheral side of the right retainer 41, and a bearing 24 is press-fitted between the nut 41H and the 3 rd differential case 27.

The pressure ring 43 is provided between the right retainer 41 and the non-rotating disk 39. The pressure ring 43 moves in the axial direction by being pressed by the piston 46, and presses the non-rotating disk 39 toward the rotating disk 38 via the pressing plate 40. As shown in fig. 11, the pressure ring 43 is formed as an annular body having a smaller outer diameter than the flange portion 27B of the 3 rd differential case 27. On the outer peripheral side of the pressure ring 43, 4 protruding portions 43A protruding radially outward are provided at angular intervals of 90 °. Pin insertion holes 43B are formed in the 4 protruding portions 43A, respectively. The pin insertion holes 43B correspond to screw holes 26J formed in the recesses 26H of the 2 nd differential case 26.

Further, a plurality of (for example, 8) rectangular projections 43D are provided on an end surface 43C of the pressure ring 43, which faces the 3 rd differential case 27 in the axial direction, in a protruding manner. The rectangular projections 43D are inserted into the rectangular holes 27F of the 3 rd differential case 27. The distal end of each rectangular projection 43D abuts against the pressing plate 40.

The 4 pins 44 are provided in the respective recesses 26H of the 2 nd differential case 26, and extend in the axial direction toward the right retainer 41. Each pin 44 has a screw portion 44A, and the screw portion 44A is screwed into a screw hole 26J formed in each recess 26H. The pins 44 protrude to the outside of the differential case 23 through the pin insertion holes 40B of the pressing plate 40 and the pin insertion holes 27E of the 3 rd differential case 27. The pin insertion holes 43B of the pressure ring 43 are inserted through the pins 44 protruding to the outside of the differential case 23. The pressure ring 43 moves in the axial direction while being guided by the respective pins 44. Further, a retaining ring 44B is attached to the projecting end side of each pin 44. The retainer ring 44B prevents the pressure ring 43 from coming off in the axial direction.

The 4 return springs 45 are located between the respective recesses 26H of the 2 nd differential case 26 and the pressing plate 40, and are provided on the outer peripheral side of the respective pins 44. Each return spring 45 is formed of a compression coil spring, and biases the pressing plate 40 toward the piston 46 (toward the 3 rd differential case 27).

The piston 46 is provided in the piston housing portion 41D of the right retainer 41. As shown in fig. 12 and 13, the piston 46 is formed in a belt-stepped cylindrical shape having a large-diameter cylindrical portion 46A and a small-diameter cylindrical portion 46B. An annular inner convex portion 46C protruding radially inward is provided on the inner peripheral side of the boundary between the large-diameter cylindrical portion 46A and the small-diameter cylindrical portion 46B. Here, the outer diameter dimension of the large-diameter cylindrical portion 46A is set to be equal to the outer diameter dimension of the cylindrical portion 41A of the right retainer 41. The inner peripheral surface 46D of the large diameter cylindrical portion 46A is slidably fitted to the outer peripheral surface of the large diameter stepped portion 41E of the right retainer 41. An inner peripheral surface 46E of the inner diameter convex portion 46C is slidably fitted to an outer peripheral surface of the small diameter stepped portion 41F of the right retainer 41.

In this way, the right retainer 41 is provided with a piston housing portion 41D including a large diameter step portion 41E and a small diameter step portion 41F having a smaller outer diameter dimension than the cylindrical portion 41A. The piston 46 is attached to the piston housing portion 41D of the right retainer 41. Accordingly, the outer diameter of the large diameter cylindrical portion 46A of the piston 46 is equal to the outer diameter of the cylindrical portion 41A of the right retainer 41. The piston 46 is inserted into a through hole 14D formed in the right partition wall 14C of the differential main body 14 in a state of being assembled to the piston housing portion 41D of the right retainer 41. In this state, the piston 46 can be brought into contact with the pressure ring 43 via a thrust bearing 48 described later by fixing the right retainer 41 to the right bulkhead 14C.

An end surface of the inner convex portion 46C of the piston 46 on the small-diameter cylindrical portion 46B side serves as an annular pressing surface 46F that presses the pressure ring 43. On the other hand, an annular entire circumferential groove 46G is formed in an end surface of the inner diameter convex portion 46C opposite to the pressing surface 46F (on the large diameter cylindrical portion 46A side). An annular hydraulic chamber 47 is formed around the entire circumference between the entire circumferential groove 46G and the end surface 41G of the piston housing portion 41D of the right retainer 41. Therefore, the hydraulic pressure is supplied to the hydraulic chamber 47, and the piston 46 moves in the axial direction to press the pressure ring 43.

An annular thrust bearing 48 is provided between the pressing surface 46F of the piston 46 and the pressure ring 43. The thrust bearing 48 is positioned in the radial direction by being disposed on the inner peripheral side of the small-diameter cylindrical portion 46B of the piston 46. Therefore, the piston 46 can press the pressure ring 43 via the thrust bearing 48, and friction can be suppressed from being generated between the piston 46 and the pressure ring 43.

The oil passage 49 is provided in the right partition wall 14C of the differential main body 14 and the right retainer 41, and supplies and discharges hydraulic oil (hydraulic pressure) to and from the hydraulic chamber 47. The oil passage 49 is constituted by a bulkhead-side oil passage 49A formed in the right bulkhead 14C and a retainer-side oil passage 49B formed in the right retainer 41. The inlet of the partition-side oil passage 49A opens on the outer peripheral surface of the differential main body 14. An outlet port of the retainer-side oil passage 49B is open to an end surface 41G of the piston housing portion 41D of the right retainer 41. A hydraulic pressure source (not shown) is connected to an inlet of the partition-side oil passage 49A. The hydraulic oil discharged from the hydraulic source is supplied to the hydraulic chamber 47 through the partition-side oil passage 49A and the retainer-side oil passage 49B.

Thereby, the piston 46 presses the pressure ring 43 in the axial direction via the thrust bearing 48. The rectangular projections 43D of the pressure ring 43 press the pressing plate 40 against the non-rotating disk 39 against the spring force of the return springs 45. Thus, each non-rotating disc 39 and each rotating disc 38 are in frictional contact between the 2 nd differential case 26 and the piston 46. Thus, when the torque difference between the left axle 19L and the right axle 19R is equal to or less than the torque capacity of the clutch, the differential mechanism 20 is in the locked state (differential locked state). As a result, the left and right side gears 34, 35 rotate integrally with the differential case 23, and torque is transmitted to the left and right axles 19L, 19R, respectively.

On the other hand, when the supply of the hydraulic oil to the hydraulic chamber 47 is stopped, the pressing plate 40 and the piston 46 are moved in a direction away from the non-rotating disk 39 by the spring force of each return spring 45. Thereby, the contact state between the non-rotating disks 39 and the rotating disks 38 is released, the right-side gear 35 can rotate relative to the differential case 23, and the differential function is enabled. As a result, the rotational force of the engine 7 is distributed to the left front wheel 5 and the right front wheel 5 according to the difference in frictional force between the left and right front wheels 5 and the road surface.

The exhaust passage 50 is provided in the right bulkhead 14C and the right retainer 41 of the differential main body 14. The exhaust passage 50 is a passage for discharging air in the hydraulic chamber 47 to the outside when the piston 46 is assembled to the piston housing portion 41D of the right retainer 41. As shown in fig. 14, the exhaust passage 50 is composed of a bulkhead-side passage 50A formed in the right bulkhead 14C and a retainer-side passage 50B formed in the right retainer 41. One end 50A1 of partition-side passage 50A is open at an end face of right partition 14C with which flange portion 41B of right retainer 41 abuts. The other end 50A2 of the partition-side passage 50A opens on the outer peripheral surface of the differential main body 14. One end 50B1 of the retainer side passage 50B opens into the piston housing portion 41D. The other end 50B2 of the retainer-side passage 50B is open at the axial end face of the flange portion 41B, and communicates with one end 50A1 of the partition-side passage 50A. Thus, when the piston 46 is assembled to the piston housing portion 41D of the right retainer 41, air in the hydraulic chamber 47 is discharged to the outside through the retainer-side passage 50B and the partition-wall-side passage 50A. Therefore, the piston 46 can be smoothly assembled to the piston housing portion 41D. After the piston 46 is assembled, the other end 50A2 of the partition-side passage 50A is closed by a sealing plug (not shown).

The left planetary gear reduction mechanism 51L is provided in the reduction gear chamber 15B of the left shaft tube 15L (see fig. 2). The planetary gear reduction mechanism 51L is composed of a sun gear 36A, a ring gear 52, a plurality of planetary gears 53, and a carrier 54, which are integrally formed on the distal end side of the left propeller shaft 36. The ring gear 52 is provided on the inner peripheral side of the shaft tube 15L (cylindrical portion 15A). A plurality of planet gears 53 mesh with the sun gear 36A and the ring gear 52. The carrier 54 rotatably supports each planetary gear 53 and spline-couples the planetary gears to the axle 19L. Therefore, the rotation of the left propeller shaft 36 is transmitted to the axle 19L in a state of being reduced in speed by the planetary gear reduction mechanism 51L.

The right planetary gear speed reduction mechanism 51R is provided in the speed reducer chamber 15B of the right shaft tube 15R. The planetary gear reduction mechanism 51R includes a sun gear 37A, a ring gear 52, a plurality of planetary gears 53, and a carrier 54, which are integrally formed on the distal end side of the right transmission shaft 37, similarly to the left planetary gear reduction mechanism 51L. The carrier 54 is spline-coupled to the axle 19R. Therefore, the rotation of the right propeller shaft 37 is transmitted to the axle 19R in a state of being reduced in speed by the planetary gear reduction mechanism 51R.

The left brake mechanism 55L is provided in the left brake chamber 14F of the differential main body 14. The brake mechanism 55L is configured as a wet multi-plate type brake mechanism, for example. The brake mechanism 55L includes a plurality of brake disks (brake disks) 57 spline-coupled to the outer peripheral side of the left transmission shaft 36 via the boss 56, a brake pad (brake plate)58, and a brake piston 59. Each brake disk 57 rotates integrally with the left transmission shaft 36. The brake pad 58 is disposed to face the brake disk 57 and is held in a non-rotating state with respect to the differential main body 14. The brake piston 59 presses the brake pad 58 against the brake disk 57 by hydraulic pressure from the outside. This applies a braking force to the left propeller shaft 36.

The right brake mechanism 55R is provided in the right brake chamber 14G of the differential main body 14. The brake mechanism 55R is configured by a plurality of brake discs 57 spline-coupled to the outer peripheral side of the right propeller shaft 37 via a boss portion 56, a brake pad 58, and a brake piston 59, as in the case of the left brake mechanism 55L. The brake piston 59 presses the brake pad 58 against the brake disk 57 by hydraulic pressure from the outside. This applies a braking force to the right propeller shaft 37.

The front axle device 12 of the present embodiment has the above-described configuration, and the operation of the front axle device 12 when the wheel loader 1 travels will be described below.

When an operator riding on the cab 10 operates the engine 7, the rotational force of the engine 7 is transmitted to the input shaft 17 via the propeller shaft 9B of the transmission 9. The rotation of the input shaft 17 is transmitted from the drive pinion 17B to the ring gear 30 of the differential mechanism 20, so that the differential case 23, to which the ring gear 30 is mounted, rotates.

The shafts 32A of the cross shafts 32 are sandwiched between the recess 25H of the 1 st differential case 25 and the recess 26E of the 2 nd differential case 26 that constitute the differential case 23. Therefore, the cross 32 rotates together with the differential case 23 in a state where the 4 pinions 33 are supported by the shafts 32A.

Here, in a state where the hydraulic oil from the hydraulic pressure source is not supplied to the hydraulic pressure chamber 47 formed between the piston housing portion 41D and the piston 46 of the right retainer 41, the pressing plate 40 is biased in a direction away from the non-rotating disk 39 by the spring force of each return spring 45. Thereby, the respective non-rotating disks 39 and the respective rotating disks 38 are kept in a non-contact state with each other.

The differential case 23 rotates together with the respective pinions 33, and thereby the left side gear 34 and the right side gear 35 meshing with the respective pinions 33 rotate. The rotation of the left propeller shaft 36 coupled to the left side gear 34 is transmitted to the axle 19L in a state of being reduced in speed by the planetary gear reduction mechanism 51L. Similarly, the rotation of the right transmission shaft 37 coupled to the right gear 35 is transmitted to the axle 19R in a state of being reduced by the planetary gear reduction mechanism 51R. Therefore, the left and right front wheels 5 are simultaneously rotationally driven.

Here, when the friction force between the left front wheel 5 and the road surface and the friction force between the right front wheel 5 and the road surface are equal to each other when the wheel loader 1 travels straight, the left and right side gears 34 and 35 rotate integrally with the differential case 23. As a result, the rotational force of the engine 7 is transmitted to the left and right front wheels 5 uniformly, and the wheel loader 1 can be driven straight.

Further, when the wheel loader 1 is rotationally driven, the left side gear 34 and the right side gear 35 rotate at different rotational speeds from each other when the frictional force between the left side front wheel 5 and the road surface and the frictional force between the right side front wheel 5 and the road surface are different. Accordingly, the rotational force of the engine 7 is distributed to the left front wheel 5 and the right front wheel 5 according to the difference between the frictional force between the left and right front wheels 5 and the road surface, and therefore the wheel loader 1 can be rotationally driven.

On the other hand, when the wheel loader 1 travels on a sand, muddy road, or the like, the state of the road surface with which the left front wheel 5 is in contact may be different from the state of the road surface with which the right front wheel 5 is in contact. In this case, it is necessary to avoid one of the left and right front wheels 5 from idling by the differential mechanism 20.

In this case, for example, a foot pedal, a manual switch, or the like (both not shown) provided in the cab 10 is operated. Thus, the hydraulic oil from the hydraulic source is supplied to the hydraulic chamber 47 through the bulkhead side oil passage 49A of the differential main body 14 and the retainer side oil passage 49B of the right retainer 41.

Therefore, the piston 46 presses the pressure ring 43 in the axial direction via the thrust bearing 48. The rectangular projections 43D of the pressure ring 43 press the pressing plate 40 against the non-rotating disk 39 against the spring force of the return springs 45. Thus, each non-rotating disc 39 makes shaft frictional contact with each rotating disc 38 between the 2 nd differential case 26 and the piston 46. Thus, when the torque difference between the left axle 19L and the right axle 19R is equal to or less than the torque capacity of the clutch, the differential mechanism 20 is in the locked state (differential locked state). As a result, the left and right side gears 34, 35 rotate integrally with the differential case 23, and transmit torque to the left and right axles 19L, 19R, respectively. Therefore, one of the left and right front wheels 5 can be prevented from idling, and the wheel loader 1 can be driven.

Here, when the differential mechanism 20 of the present embodiment is incorporated into the gear chamber 14E of the differential main body 14, the pinion gears 33, the left and right side gears 34, 35, the rotary plate 38, the non-rotary plate 39, and the like are incorporated into the differential case 23. In addition, the ring gear 30 is assembled in the 1 st differential case 25, and the pins 44 are mounted in the respective screw holes 26J of the 2 nd differential case 26. In a state where the return spring 45 is disposed on the outer peripheral side of each pin 44, each pin 44 is inserted into the pin insertion hole 27E of the 3 rd differential case 27. The pin insertion holes 43B of the pressure ring 43 are inserted into the pins 44, and the rectangular projections 43D of the pressure ring 43 are inserted into the rectangular holes 27F of the 3 rd differential case 27. In this state, a retainer ring 44B is attached to the projecting end of each pin 44.

Then, the differential case 23 with the pressure ring 43 attached thereto is inserted into the gear chamber 14E of the differential main body 14. In this state, left retainer 21 is inserted into through-hole 14D of left partition wall 14B, and flange 21A is attached to left partition wall 14B. Thereby, the 1 st differential case 25 is held by the left retainer 21 via the bearing 24. On the other hand, the piston 46 is assembled to the piston housing portion 41D of the right retainer 41. In this state, the piston 46 and the cylindrical portion 41A of the right retainer 41 are inserted through the through hole 14D formed in the right bulkhead 14C of the differential main body 14, and the flange portion 41B is attached to the right bulkhead 14C. Thereby, the 3 rd differential case 27 is held by the right retainer 41 via the bearing 24. At this time, the piston 46 can be brought into contact with the pressure ring 43 via the thrust bearing 48.

As described above, according to the present embodiment, the piston housing portion 41D is formed in the right retainer 41 attached to the right partition wall 14C of the differential case 14, and the piston 46 can be assembled in the piston housing portion 41D. Therefore, it is not necessary to form a piston housing portion on the gear chamber 14E side surface of the right partition wall 14C. Thus, the differential main body 14 having a one-piece structure in which the left and right partition walls 14B, 14C that define the gear chamber 14E are integrally formed can be used. Therefore, the structure of the differential main body 14 can be simplified as compared with the case where the piston housing portion is formed in the partition wall of the differential main body. As a result, the entire structure of the front axle device 12 can be simplified, which contributes to cost reduction.

After the differential case 23 is inserted into the gear chamber 14E of the differential main body 14, the right retainer 41 incorporating the piston 46 can be attached to the right bulkhead 14C. Thereby, the piston 46 can be brought into contact with the pressure ring 43 via the thrust bearing 48. As a result, workability when assembling the piston 46 to the differential mechanism 20 housed inside the differential main body 14 can be improved. Further, the assembly work of the piston 46 in the gear chamber 14E of the differential main body 14 is not required. Therefore, the differential case 23 disposed in the gear chamber 14E can be configured to be large, and the number of the rotary disks 38 and the non-rotary disks 39 can be increased, for example.

Thus, according to the embodiment, the front axle device 12 has the differential mechanism 20 that transmits the rotational force of the engine 7 to the left and right axles 19L, 19R. The differential mechanism 20 includes: a differential case 23 rotatably supported by left and right cages 21 and 41 via bearings 24 and rotated by the engine 7, the left and right cages 21 and 41 being attached to the through-holes 14D of the left and right partition walls 14B and 14C, respectively; a plurality of pinion gears 33 provided in the differential case 23 and rotating together with the differential case 23; left and right side gears 34, 35 provided in the differential case 23 and meshing with the respective pinions 33; and left and right propeller shafts 36, 37 connected to the side gears 34, 35, respectively, and transmitting rotation of the differential case 23 to the left and right axles 19L, 19R.

Further, a plurality of rotary disks 38 and a plurality of non-rotary disks 39 are provided in the differential case 23, the plurality of rotary disks 38 are spline-coupled to the outer peripheral side of the right gear 35, the plurality of non-rotary disks 39 are disposed between the rotary disks 38 and are non-rotatable and movable in the left-right direction with respect to the differential case 23, a pressure ring 43 for pressing the non-rotary disks 39 toward the rotary disks 38 is provided between the right guard ring 41 and the non-rotary disks 39 located on the right gear 35 side, a piston housing portion 41D is provided at a position of the right guard ring 41 opposed to the pressure ring 43 in the left-right direction, a piston 46 is provided in the piston housing portion 41D, and the non-rotary disks 39 are pressed against the rotary disks 38 via the pressure ring 43 by hydraulic displacement of the piston 46 to couple the.

According to this configuration, since the piston 46 can be assembled to the piston housing portion 41D formed in the right retainer 41, it is not necessary to form a piston housing portion on the gear chamber 14E side surface of the right partition wall 14C. Thus, the differential main body 14 having a one-piece structure in which the left and right partition walls 14B, 14C that define the gear chamber 14E are integrally formed can be used. Therefore, the structure of the differential main body 14 can be simplified as compared with the case where the piston housing portion is formed in the partition wall of the differential main body.

According to the embodiment, a hydraulic chamber 47 is formed between the piston 46 and the piston housing portion 41D of the right retainer 41, hydraulic oil for pressing the piston 46 is supplied to the hydraulic chamber 47, and an oil passage 49 for connecting a hydraulic source and the hydraulic chamber 47 is formed in the right partition wall 14C of the differential main body 14 and the right retainer 41. According to this structure, the hydraulic oil from the hydraulic pressure source is supplied to the hydraulic chamber 47 through the oil passage 49 formed in the right partition wall 14C and the right retainer 41. Therefore, it is not necessary to connect a hydraulic line formed of a member other than the right retainer 41 to the hydraulic chamber 47, and the structure of the differential mechanism 20 can be simplified.

According to an embodiment, the differential case 23 comprises: a1 st differential case 25 rotatably supported by the left retainer 21, having a ring gear 30 on an outer circumferential side and a left gear 34 on an inner circumferential side; a2 nd differential case 26 attached to the 1 st differential case 25 and provided with a right side gear 35 on an inner peripheral side; and a 3 rd differential case 27 attached to the 2 nd differential case 26 on the opposite side to the 1 st differential case 25 in the left-right direction and rotatably supported by the right retainer 41, wherein the rotary disks 38 and the non-rotary disks 39 are disposed between the inner peripheral side of the 2 nd differential case 26 and the axial spline portion 35B of the right gear 35, and the piston 46 can press the non-rotary disks 39 via a pressure ring 43 inserted into the 3 rd differential case 27.

According to the embodiment, a pressing plate 40 is provided between the non-rotating disk 39 and the pressure ring 43, the pressing plate 40 presses the non-rotating disk 39 when the piston 46 is operated and the pressure ring 43 moves toward the non-rotating disk 39, a pin 44 inserted into the 3 rd differential case 27 and the pressing plate 40 is provided between the 2 nd differential case 26 and the pressure ring 43, and a return spring 45 is provided between the 2 nd differential case 26 and the pressing plate 40, the return spring 45 being disposed on the outer peripheral side of the pin 44 and biasing the pressing plate 40 toward the piston 46.

According to this configuration, when the supply of the hydraulic oil to the hydraulic chamber 47 is stopped, the pressing plate 40 and the piston 46 are moved in a direction away from the non-rotating disk 39 by the spring force of the return spring 45. Thereby, the contact state between the non-rotating disks 39 and the rotating disks 38 is released, the right-side gear 35 can rotate relative to the differential case 23, and the differential function is enabled. As a result, the rotational force of the engine 7 can be distributed to the left front wheel 5 and the right front wheel 5 according to the difference in frictional force between the left and right front wheels 5 and the road surface.

In the embodiment, the wheel loader 1 is exemplified as a vehicle to which the rear axle device 11 and the front axle device 12 are applied. However, the present invention is not limited to this, and can be widely applied to other wheel-type construction machines such as a wheel excavator.

Description of the reference numerals

1 wheel loader

4 rear wheel

5 front wheel

7 Engine (Driving source)

11 rear axle device

12 front axle device

14 differential main body

14B left bulkhead

14C right bulkhead

14D through hole

15L, 15R axle tube

19L, 19R axle

20 differential mechanism

21 left guard ring (the other side guard ring)

23 differential case

25 1 st differential case

26 nd 2 nd differential case

27 rd 3 differential case

30 Ring Gear

33 pinion

34 left side gear

35 Right side gear (one side gear)

36 left transmission shaft

37 right transmission shaft

38 rotating disc

39 non-rotating disc

40 pressing plate

41 Right guard ring (Square guard ring)

41D piston housing

43 pressure ring

44 pin

45 return spring

46 piston

47 hydraulic chamber

49 oil path.