JPH0472090B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a piston return mechanism for a wet brake, and more particularly to a piston for a wet brake that uses a hydraulically driven piston to push a brake disk that rotates together with a rotating shaft in the axial direction. Regarding the return mechanism.

[Prior art]

In general, a vehicle wet brake system installed on an accelerator device with a planetary gear reducer includes a brake disc, disc plate, brake plate,
It consists of an annular piston, a piston return mechanism, etc., and the annular piston is disposed in an annular cylinder groove formed in the internal gear hub via a pair of O-rings, and by driving the annular piston with hydraulic pressure, the rotating shaft is Braking is performed by sandwiching the spline-fitted brake disc between the disc plate and the brake plate, and a piston return mechanism is used to return the annular piston so that the disc plate and brake plate do not come into sliding contact with the brake disc except during braking. It is structured as follows.

Conventionally, as the above-mentioned piston return mechanism, for example, in Japanese Utility Model Publication No. 107639/1983, a coil spring is installed in a spring recess formed in an internal gear hub, and one end of a pin member connected to the piston is connected to a coil spring. A device is described in which the piston is connected to a spring and the piston is returned via a pin member by the elastic force of the coil spring.

In addition, as a brake device other than the one in which an annular piston is hydraulically driven as described above, for example, Japanese Patent Application Laid-Open No. 59-194138 discloses a pair of annular flanges on the inside of a tire wheel that rotate integrally with the tire wheel. disposing a disk member having a portion;
A substantially annular metal bellow is disposed in the annular space between both flanges of this disk member via a friction lining, and when the bellow is driven, the bellows extend in the axial direction by hydraulic pressure, and the bellows A hydraulic brake braking device is described in which the flange portion of the disk member is pressed by both inner and outer end surfaces to perform braking, and the bellows are contracted by the elastic force of the bellows except during braking.

[Problem that the invention seeks to solve]

In the wet brake piston return mechanism described in the above publication, the annular piston is returned to a predetermined position by the elastic force of a coil spring connected to the piston, so parts such as a coil spring and a pin member that constitute the piston return mechanism The number increases, the structure is complicated, and the use of coil springs increases the size and length in the width direction, and also increases the cost.

Further, since the O-ring disposed in the cylinder comes into sliding contact with the outer peripheral surface of the annular piston when the annular piston is driven, the O-ring needs to be replaced from time to time as the sealing performance deteriorates due to wear of the O-ring.

In addition, in the hydraulic brake actuating device described in the above publication, the bellows return to its original position due to the elastic force of the bellows, so a piston return mechanism is not required. Oil injection requires a lot of effort.

Furthermore, the above-mentioned annular bellows is disposed on the outer end surface of the internal gear hub, and by driving the bellows with hydraulic pressure, the brake disc is sandwiched between the disc plate and the brake plate, and braking is performed. It may be possible to contract the bellows using elastic force, but the bellows would be very large in the axial direction, resulting in high costs and would be impractical when applied to an axle device with many space constraints.

[Means for solving problems]

The wet brake according to the present invention is a wet brake of a type in which a brake disc rotating together with a rotating shaft is pressed in the axial direction with a hydraulically driven annular piston in a gear chamber. An annular pressing part, a pair of annular curved parts each having a substantially U-shaped cross section formed on the inner and outer peripheral sides of the pressing part, and a pair of annular curved parts formed on the inner and outer peripheral parts, respectively. An annular plate-shaped elastic member having an annular attachment portion is fixed in an oil-tight manner via a pair of attachment portions, and an annular hydraulic operating chamber is formed between the elastic member and the wall portion, The piston is disposed between the brake disk and the elastic member and fixed to the pressing part of the elastic member, and the elastic member is elastically deformed by the hydraulic pressure in the hydraulic chamber to press the piston toward the brake disk, and The piston is configured to return to its original position by the elastic return force of the elastic member while the hydraulic pressure in the hydraulic chamber is drained.

[Effect]

The wet brake according to the present invention includes an annular pressing portion, a pair of annular curved portions having a U-shaped cross section on both the inner and outer sides thereof, and a pair of annular mounting portions on both the inner and outer sides of these inner and outer curved portions. An annular and plate-shaped elastic member provided with the above is fixed to the wall surface of the wall portion facing the brake disc via the pair of attachment portions, and a hydraulic operating chamber is formed between the elastic member and the wall portion, An annular piston is fixed to a pressing part, and an elastic member is elastically deformed by hydraulic pressure to cause a braking action on the piston.
Further, the piston is configured to return to its original position by the elastic restoring force of the elastic member while the hydraulic pressure in the hydraulic chamber is drained.

Therefore, the structure for braking the piston and the structure for the piston return mechanism can be made small and simple, consisting of a small number of parts, reducing their manufacturing costs, and omitting O-rings on both the inner and outer sides of the piston. As a result, the durability of the piston braking mechanism can be improved, and the operation reliability of the piston return mechanism can be improved. Also, since the hydraulic chamber has a simple shape that is flat in the axial direction, it is possible to improve the durability of the piston braking mechanism. This makes it easier to bleed air from the air.

〔Effect of the invention〕

According to the wet brake according to the present invention, as explained in the operation section above, by mainly comprising an annular and plate-shaped elastic member, the structure for braking the piston and the structure of the piston return mechanism are It is possible to have a small and simple structure consisting of a small number of parts, reducing the manufacturing cost, and since O-rings on both the inner and outer sides of the piston can be omitted, the durability of the structure for braking the piston can be improved, and the piston return mechanism can be reduced. can improve the operational reliability of the
Since the hydraulic chamber has a simple shape that is flat in the axial direction, it is easy to bleed air from the hydraulic chamber when filling oil.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, an axle device 2 provided at the shaft end of a drive shaft 1 that drives the drive wheels of a vehicle has a planetary gear reducer 3 as a final reduction device.
and a brake device 4, and is fixed to a tire wheel 6 at the outer periphery of the outer end surface of the carrier 5 of the planetary gear reducer 3.

The axle housing 7 is fitted onto the drive shaft 1 and fixed to the vehicle body, and is attached to the tire wheel 6.
The outer end is fitted into the hub body 9 of the internal gear hub 8 by spline fitting, and the nut 10 is screwed to the end to fix it to the internal gear hub 8. has been done.

The internal gear hub 8 is composed of a hub body 9 and a cylindrical ring member 11. An internal gear 12 is formed on the inner peripheral surface of the ring member 11. Main body 9
The hub body 9 and the ring member 11 are integrally connected by fitting the spline teeth 9a and fitting the strip ring 13 between the internal gear 12 and the hub body 9. However, the hub body 9 and the ring member 11 may be formed integrally.

The outer circumferential side of the internal gear hub 8 is surrounded by a wheel hub 14, and the outer circumferential end of the wheel hub 14 is fixed to the tire wheel 6 with bolts 15 together with the outer circumferential edge of the carrier 5, and the inner inner circumferential portion of the inner gear hub 8 is surrounded by a wheel hub 14. A pair of bearings 39 are installed inside and rotatably supported by the hub body 9 and the axle housing 7.

The planetary gear reducer 3 includes a carrier 5, a ring gear 12 of a ring member 11 of an internal gear hub 8, and a spline shaft portion 16 at an end of a drive shaft 1.
It consists of a sun gear 17 spline-fitted to the carrier 5, four planetary pins 19 attached to the carrier 5, and four planetary gears 20 rotatably supported by the planetary pins 19 via bearings 18. , the planetary gear 20 meshes with the sun gear 17 and also meshes with the ring gear 12 of the ring member 11, and the planetary pin 19
It rotates around the drive shaft 1 and rotates integrally with the carrier 5 and the wheel hub 14,
A tire wheel 6 fixed to a carrier 5 is rotated at a reduced speed about a drive shaft 1.

The planetary pin 19 has both ends inserted into and supported by the carrier 5, and the drive shaft 1 on the outer end surface.
An annular washer 21 is fixed to an eccentric position on the side with a bolt 22. The inner circumference of the washer 21 is the carrier 5
The bolt 22 pulls the planet pin 19 outward through the washer 21, and the bolt 24 pulls the carrier 5.
The head of the bolt 22 is accommodated in a groove 23a formed inwardly of a cover plate 23 fixed to the carrier 5, thereby preventing the planetary pin 19 from rotating relative to the carrier 5.

The brake device 4 includes a shallow annular hydraulic chamber 25 formed at the outer end of the hub body 9 in the middle in the radial direction, an annular piston 26 disposed outside the hydraulic chamber 25, and a piston. The piston 2 is fixed, for example, by adhesive, over the entire inner end surface of the piston 2.
6, a substantially flat annular elastic member 27 made of a single metal plate extending outside the inner circumferential edge and outer circumferential edge of the elastic member 27;
A pair of annular seal rings 29 are held between the peripheral edge (flange 27a) of the hub body 9 and the hub body 9; An annular brake plate 31 , a brake sleeve 32 spline-fitted to the spline shaft portion 16 , and a brake plate 31 disposed between the carrier 5 and the hub body 9 and spline-fitted to the brake sleeve 32 .
a disc-shaped brake disk 33 extended to a radial position corresponding to the outer circumference of the brake disk 33; a pair of annular friction linings 34 lined on both the inner and outer end surfaces of the brake disk 33; and a radius corresponding to the brake plate 31. An annular disc plate 35 is disposed between the brake disc 33 and the brake plate 31 at a radial position and is spline-fitted with the ring gear 12; It consists of an annular brake plate 37 fixed to the carrier 5 with bolts 36 disposed therebetween.

Note that the piston 26 and the brake plate 31 may be formed integrally.

The elastic member 27 includes a pair of attachment portions 27a extending outside the periphery of the piston 26, and a pair of annular attachment portions 27a having a generally U-shaped cross section and bulging outward at a portion between the attachment portions 27a and the periphery of the piston 26. It is integrally formed in a substantially annular shape from a curved portion 27b for promoting elastic deformation and a pressing portion 27c that connects the curved portions 27b, and a seal ring 29 is provided between each mounting portion 27a and the hub body 9. By fixing the mounting portion 27a to the hub pair 9 with bolts 28, the seal ring 29 is held, and the hydraulic pressure supplied to the hydraulic chamber 25 is sealed.

The piston return mechanism 38 is composed of the elastic member 27 and a pair of seal rings 29, and is connected to the hydraulic chamber 25 from the hydraulic supply device (not shown) through an oil passage 40 formed in the axle housing 7 and the hub body 9. During braking when hydraulic pressure is supplied, the curved portion 27b of the elastic member 27 is bent as shown by the imaginary line in FIG.
The piston 26 and the brake plate 3 are elastically deformed outward and are fixed to the outer end surface of the pressing portion 27c.
1 to the brake plate 37 side, and when the brake is released to release the hydraulic pressure, the curved portion 27b returns with elastic force as shown by the solid line in FIG. Return to the side.

The disk plate 35 includes the ring member 11
The brake disc 33 is axially movable and rotationally restrained relative to the drive shaft 1, and the brake disc 37 is integrally connected to the carrier 5 by bolts 36. During braking, the brake disc 33 and disc plate 35 are pressed by the piston 26 toward the brake plate 37 via the brake plate 31, and the brake disc 37 and disc plate 35 push the friction lining 3
4, and when the brake is released, the piston 26 and the brake plate 31 return to the hub body 9 side, and the brake plate 37
A predetermined gap is formed between the brake disc 33 and the disc plate 35 to allow rotation of the brake disc 33.

Next, the piston return mechanism 3 of the wet brake
8 will be explained.

When the vehicle is running, a predetermined gap is formed between the brake plate 37 and the disc brake 35 to allow rotation of the brake disc 33, and the brake disc 33 rotates integrally with the drive shaft 1, and the rotational torque of the drive shaft 1 is is transmitted to the sun gear 17 and each planetary gear 20, and the tire wheel 6 is driven to rotate at a reduced speed.

When the brake pedal of the vehicle is operated to perform piston braking, which is supplied from the hydraulic pressure supply device through the oil passage 40, the hydraulic pressure chamber 2 is activated as shown by the imaginary line in FIG.
The curved portion 27b of the elastic member 27 is elastically deformed outward by the hydraulic pressure supplied to the piston 26 and the brake plate 3, and the pressing portion 27c protrudes outward.
1 to the outside, and the disc plate 35 is attached to the brake plate 37 at the outer end surface of the brake plate 31.
The brake disc 33 is sandwiched between the disc plate 35 and the brake plate 37 via the friction lining 34, and the rotational torque of the drive shaft 1 is transmitted through the brake disc 33 to the brake plate 37 and the disc plate. 35, and is decelerated by the disc plate 35, which does not rotate, and is also decelerated by the brake plate 37, which rotates at a slower speed than the brake disc 33.

Next, when the brake is released by interrupting the operation of the brake pedal of the vehicle and releasing the hydraulic pressure from the hydraulic chamber 25, the pressing portion 27c protruding outward is bent as shown in the actual situation in FIG. The elastic force of the portion 27b causes the piston 26 and the brake plate 31 to return to the hub body 9 side. Then, the brake disk 33 slides between the brake plate 37 and the disk plate 35 due to the rotational torque of the drive shaft 1, and the brake disk 33 and the disk plate 35 are gradually moved toward the hub body 9, and the brake plate 37 A predetermined gap is formed between the disc plate 35 and the disc plate 35 to allow rotation of the brake disc 33, and the braking applied to the brake disc 33 is released.

As explained above, the seal ring 29 is sandwiched between each mounting portion 27a and the hub body 9, and the hydraulic pressure supplied to the hydraulic pressure chamber 25 is sealed.
The bending portion 2 is moved by the hydraulic pressure supplied to the hydraulic working chamber 25.
Since the piston 26 is driven by elastic deformation of the piston 7b, it is possible to eliminate the O-ring with a piston drive mechanism having a simple structure, thereby improving the durability of the seal and reducing manufacturing costs.

Furthermore, when the piston is released from braking, the curved portion 27
Since the piston 26 returns due to the elastic force of b,
The structure of the piston return mechanism can be simplified, the wall thickness of the hub body 9 in the vehicle width direction can be made thinner, and since the elastic member 27 has a substantially flat annular shape, it can be disposed in a small space in the vehicle width direction. The whole can be configured compactly.

In addition, in this embodiment, one disk plate 3
Although the piston return mechanism 38 of the present invention has been applied to the brake device 4 which is braked by a disc plate 5, it can also be applied to a brake device which is braked by a plurality of disc plates.

Further, the piston 26 is connected to the brake disc 3.
The pistons may be arranged on the hub body 9 and carrier 5 on both sides of the brake disc 3, so that each piston presses the brake disc 33 from both sides and clamps the disc plate 35 disposed between the brake discs to perform braking. It's okay.

[Brief explanation of the drawing]

1 is a longitudinal sectional view of an axle device, and FIG. 2 is a longitudinal sectional view of a main part in the vicinity of a piston return mechanism. 1... Drive shaft, 4... Brake device, 26...
Piston, 27...Elastic member, 27a...Mounting portion, 33...Brake disc, 35...Disc plate, 38...Piston return mechanism.

Claims (1)

[Scope of Claims] 1. In a wet brake of the type in which a hydraulically driven annular piston presses a brake disc that rotates together with a rotating shaft in the axial direction in a gear chamber, an annular shaped a pressing part, a pair of annular curved parts each having a substantially U-shaped cross section formed on the inner and outer peripheral sides of the pressing part, and a pair of annular curved parts formed on the inner and outer peripheral parts, respectively. an annular plate-shaped elastic member having an annular attachment portion is fixed in an oil-tight manner via a pair of attachment portions, and an annular hydraulic operating chamber is formed between the elastic member and the wall portion; A piston is disposed between the brake disk and the elastic member and fixed to the pressing part of the elastic member, and the elastic member is elastically deformed by the hydraulic pressure in the hydraulic chamber to press the piston toward the brake disk. A wet brake characterized in that a piston is returned to its original position by an elastic returning force of an elastic member when hydraulic pressure in an operating chamber is drained. 2. The wet brake according to claim 1, wherein the number of brake discs is one. 3. The wet brake according to claim 1, wherein the brake disc is composed of a plurality of discs and braking is performed by a plurality of disc plates. 4. The wet brake according to claim 2 or 3, wherein the hydraulically driven piston is disposed only on one side of the brake disc. 5. The wet brake according to claim 3, wherein the hydraulically driven pistons are arranged on both sides of the brake disc.