JP2003035326A - Hydraulic clutch disengaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic clutch disengaging system which can keep a sealability even if an unbalanced load of a clutch operating member works on a piston. SOLUTION: In this hydraulic clutch disengaging system having a cylindrical piston 7 which is inserted changeably in the axial direction into the hydraulic chamber 12 from one end side, a seal ring having a lip contacted by an inner cylinder 5 and an outer cylinder 6 which are arranged in one end side of the piston 7 and constitute the hydraulic chamber 12 and a release bearing 9 which is fitted to the other end side of the piston 7 and is contacted by the operating member 3 of the clutch, the piston 7 is divided into a plurality of piston members 16, 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic clutch disengagement device that disengages a clutch installed between, for example, an automobile engine (power source) and a transmission with hydraulic pressure.

[0002]

2. Description of the Related Art Conventionally, a clutch disconnecting device of this type is known as shown in FIG. This is a hydraulic clutch disengagement device 64 that hydraulically pushes a clutch operating member 63 such as a diaphragm spring to shut off power transmission from a power source such as an engine to a transmission. Incidentally, 61 is an input shaft of the transmission, and 62 is a clutch housing.

The clutch disengagement device 64 has an inner cylinder 65, an outer cylinder 66, a piston 67, a seal ring 68, a release bearing 69, a coil spring 70, and a boot 71.

The inner cylinder 65 and the outer cylinder 66 are arranged radially inside and outside coaxially with the input shaft 61 inserted through the inner circumference of the inner cylinder 65, and fixed to the clutch housing 62. A hydraulic chamber 72 formed of an annular space is formed between the inner cylinder 65 and the outer cylinder 66. The hydraulic chamber 72 is supplied with hydraulic oil having a pressure corresponding to the operation amount from a master cylinder (not shown) through a hydraulic pressure introducing passage 73 formed in the outer cylinder 66.

The piston 67 is made of synthetic resin and formed in a cylindrical shape, and is inserted into the hydraulic chamber 72 so as to be displaceable in the axial direction. One end 67 of the piston 67 on the hydraulic chamber 72 side
A seal ring 68 is arranged at a, and the lips 68a, 6 formed on the upper and lower sides of the seal ring 68 in the radial direction.
8b is in sliding contact with the inner peripheral surface 66a of the outer cylinder 66 and the outer peripheral surface 65a of the inner cylinder 65 to seal the hydraulic chamber 72. The seal ring 68
The projection 68c formed on the seal ring 68 on the side opposite to the lip is fixed to the circumferential groove 74 on the end surface of the piston 67 by concave-convex fitting.

The release bearing 69 has an annular flange 75 which is erected on the other end 67b of the piston 67 on the clutch side.
It is mounted so that it can be self-aligned in the radial direction. Specifically, in the release bearing 69, an outer ring 69a is mounted on the annular flange 75 so as to be capable of self-alignment in the radial direction, and an inner ring 69b rotatably mounted on the outer ring 69a via a rolling element 69c is a diaphragm spring. It is brought into contact with the inner edge of 63.

The coil spring 70 is interposed on the outer circumference of the outer cylinder 66 in a compressed state, and a bellows-shaped boot 71 is attached to the outer circumference of the coil spring 70.

The operation of the hydraulic clutch disengagement device 64 will be described. The hydraulic pressure corresponding to the operation amount moves the piston 67 and the release bearing 69 in the axial direction, and the inner ring 69b of the release bearing 69 causes the diaphragm spring 63 to move. The inner edge of the shaft is pushed in the axial direction, whereby the pressure plate (not shown) attached to the outer edge of the diaphragm spring 63 is pulled away from the clutch disc (not shown) side to shut off the power transmission from the engine to the transmission. To do.

[0009]

In the conventional hydraulic clutch disconnecting device 64, as understood from the above, the load of the diaphragm spring 63 is sequentially transmitted to the release bearing 69, the piston 67, and the seal ring 68. On the contrary, the hydraulic pressure from the master cylinder is sequentially transmitted to the seal ring 68, the piston 67, and the release bearing 69.

By the way, the inner edge of the diaphragm spring 63 is formed of a plurality of spring members 63a which act as springs on the circumference, as is well known, and the axial height dimension of each spring member 63a is perfect. It is difficult to make the same product. Therefore, when the load of the diaphragm spring 63 acts on the inner ring 69b of the release bearing 69, an eccentric load that acts on the spring members 63a due to the non-uniform axial height dimension acts.
For this reason, the piston 67 and the seal ring 68 connected to the release bearing 69 are tilted by the unbalanced load and reciprocate in the hydraulic chamber 72 in the axial direction.

As a result, the upper lip 6 of the seal ring 68 is
8a and the inner peripheral surface 66a of the outer cylinder 66, and the contact pressure between the lower lip 68b and the outer peripheral surface 65a of the inner cylinder 65 are reciprocated in a changed state. There is a problem that uneven wear of 68b occurs and oil leakage occurs.

Further, the piston 67 and the inner cylinder 6
5 and the outer cylinder 66, the clearance is set to be a small clearance in order to maintain the sealing performance of the seal ring 68. Therefore, when the piston 67 reciprocates in a tilted state, the tip portion of the piston 67 causes Each cylinder 65,
There is a problem that the peripheral surfaces 65a, 66a of the 66 are scratched and oil leaks.

Furthermore, since the piston 67 has an integral structure and becomes long in the axial direction, when molding from synthetic resin, in order to secure the inner and outer diameter dimensions of the inner end portion 67a of the piston 67 that most affect the sealing performance. There is a problem that a complicated mold structure is required.

Furthermore, since the piston 67 has an integral structure, it is formed of one material, which makes it difficult to use an inexpensive material.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the conventional device, and more particularly to provide a hydraulic clutch disengagement device which can maintain the sealing performance even when an unbalanced load of the clutch operating member acts on the piston.

[0016]

As a means for solving the above-mentioned problems, the invention of claim 1 is such that an inner cylinder fixedly arranged and through which an input shaft of a transmission is inserted, and an annular shape on the outer circumference of the inner cylinder. An outer cylinder fixedly arranged to form a hydraulic chamber consisting of a space, a cylindrical piston that is axially displaceably inserted into the hydraulic chamber from one end side, and the inner cylinder arranged on one end side of the piston A seal ring having a seal lip that is brought into contact with the outer peripheral surface and the inner peripheral surface of the outer cylinder, and a release bearing that is attached to an annular flange erected on the other end side of the piston and abuts against a clutch operating member. In the hydraulic clutch disengagement device having the above, the piston has a position where the annular flange is erected and a position where the seal ring is attached. Characterized in that it is divided into a plurality of piston members in the axial direction arbitrary position.

The invention according to claim 2 is characterized in that, of the plurality of piston members, the outer diameter of the piston member on which the annular flange is erected is smaller than the outer diameter of other piston members. And

Further, in the invention of claim 3, among a plurality of piston members, a piston in which the annular flange is erected between an end surface of a piston member in which the annular flange is erected and an end surface of an adjacent piston member. It is characterized in that a tilt absorbing portion of the member is provided.

Further, the invention of claim 4 is characterized in that the inclination absorbing portion is an end surface of an arcuate section of a piston member on which the annular flange is erected.

Furthermore, in the invention of claim 5, the tilt absorbing portion is a cushioning material interposed between the end surface of the piston member on which the annular flange is erected and the end surface of the adjacent piston member. Is characterized by.

Further, the invention of claim 6 is that the inclination absorbing portion is a ball interposed between the end surface of the piston member on which the annular flange is erected and the end surface of the adjacent piston member. Characterize.

Further, according to a seventh aspect of the present invention, among the plurality of piston members, when the piston member in which the annular flange is erected is attached or detached, an inner portion of a slip-out prevention mechanism for preventing axial displacement of an adjacent piston member. It is characterized in that it is formed in a cylinder.

Further, in the invention of claim 8, the slip-out preventing mechanism has a radial through hole formed in the inner cylinder, a projecting member projecting from the inner diameter side of the through hole to the outer diameter side, and an adjacent piston. It is characterized in that it is formed of a concave step portion formed on the inner peripheral surface of the member and into which the above-mentioned protruding member is inserted.

Furthermore, in the invention of claim 9, the concave step portion of the adjacent piston member is a circumferential step portion formed on the inner peripheral surface of the corner portion of the end surface on the piston member side on which the annular flange is erected. It is characterized by

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION A specific embodiment of the present invention will be described below with reference to FIG. It is a hydraulic clutch disengagement device 4 that displaces power transmission from a power source such as an engine to a transmission by pushing a clutch operating member 3 such as a diaphragm spring with hydraulic pressure. In addition, 1 is an input shaft of the transmission, and 2 is a clutch housing.

The clutch disengaging device 4 comprises an inner cylinder 5, an outer cylinder 6, a piston 7, a seal ring 8, a release bearing 9, a coil spring 10 and a boot 11.

Inner cylinder 5 and outer cylinder 6
Is the input shaft 1 inserted through the inner circumference of the inner cylinder 5.
Are arranged radially inside and outside coaxially with and fixed to the clutch housing 2. A hydraulic chamber 12 formed of an annular space between the inner cylinder 5 and the outer cylinder 6
Are formed. The hydraulic chamber 12 is supplied with hydraulic oil having a pressure corresponding to an operation amount from a master cylinder (not shown) through a hydraulic pressure introduction passage 13 formed in the outer cylinder 6.

The piston 7 is made of synthetic resin and formed in a cylindrical shape, and is inserted into the hydraulic chamber 12 so as to be displaceable in the axial direction. Further, the piston 7 is divided into two piston members 16 and 17 in the axial direction. Of course, the piston 7 is not limited to two divisions, and may be divided into a necessary number of divisions. Further, each divided portion may or may not be connected to each other.

A seal ring 8 is arranged at the inner end 16a of the piston member 16 on the side of the hydraulic chamber 12 constituting the piston 7, and the lips 8a and 8b formed on the upper and lower sides in the radial direction of the seal ring 8 are The inner peripheral surface 6a of the outer cylinder 6 and the outer peripheral surface 5a of the inner cylinder 5 are brought into sliding contact with each other to seal the hydraulic chamber 12. The seal ring 8 has a protrusion 8c formed on the seal ring 8 on the side opposite to the lips 8a and 8b, and fixed to the circumferential groove 14 on the end face of the piston member 16 by means of concave and convex fitting.

The release bearing 9 is attached to an annular flange 15 provided upright on the outer end 17b of the piston member 17 on the side of the diaphragm spring 3 constituting the piston 7 so as to be capable of self-centering in the radial direction. Specifically, in the release bearing 9, the outer ring 9a is mounted on the annular flange 15 so as to be capable of self-alignment in the radial direction, and the rolling element 9 is mounted on the outer ring 9a.
An inner ring 9b rotatably mounted via c is brought into contact with the inner edge 3a of the diaphragm spring 3.

Here, the inner ends of the piston members 16 and 17 refer to the hydraulic chamber 12 side, and the outer ends thereof refer to the diaphragm spring 3 side.

The coil spring 10 is interposed on the outer circumference of the outer cylinder 6 in a compressed state, and a bellows-shaped boot 11 is attached to the outer circumference of the coil spring 10.

The operation of such a hydraulic clutch disengagement device 4 is the same as that of the conventional device shown in FIG. When the hydraulic clutch disengagement device 14 is operated, an eccentric load from the diaphragm spring 3 acts on the piston 7 through the release bearing 9, but as in the embodiment of FIG. 1, the piston 7 has an annular shape in which the release bearing 9 is mounted. Since the piston member 17 in which the flange 15 is installed upright and the piston member 16 in which the seal ring 8 is mounted are divided into two in the biaxial direction, the unbalanced load acts only on the piston member 17, and the seal ring 8
The piston member 16 mounted with is prevented from acting, and no tilt occurs. Therefore, between the lip 8a of the seal ring 8 and the inner peripheral surface 6a of the outer cylinder 6, and between the lip 8b and the outer peripheral surface 5 of the inner cylinder 5.
A change in contact pressure between each of them and a is prevented, uneven wear due to reciprocation of the seal ring 8 due to reciprocation of the piston 7 is prevented, and there is no risk of oil leakage.

Since the piston 7 is divided,
When molded from a synthetic resin, the inner piston member 16 of the piston 7, which has the greatest effect on the sealing performance, has a relatively short axial direction, so the mold for securing the inner and outer diameter dimensions of the end 16a of the piston member 16 is simplified. .

Since the piston 7 is divided,
The material required for each of the piston members 16 and 17 is sufficient, and the cost can be easily reduced.

FIG. 2 shows a second embodiment in which, of the piston members 16 and 17, the outer diameter D1 of the outer piston member 17 on which the annular flange 15 is erected is the same as the other piston member 16. Is smaller than the outer diameter D2.
As a result, even if an eccentric load from the diaphragm spring 3 acts on the outer piston member 17 to cause an inclination, the outer diameter D1 is small, so the inner peripheral surface 6a of the outer cylinder 6 is
And the end of the piston member 17 is more reliably prevented from contacting the inner peripheral surface 6a of the outer cylinder 6. This is advantageous because the outer peripheral surface 5a of the inner cylinder 5 is hardened and hardened, whereas the outer peripheral surface 6a is easily scratched because the outer cylinder 6 is made of an aluminum alloy. Further, since the inner piston member 16 does not have a risk of tilting, the outer cylinder 6
The gap between the inner cylinder 5 and the inner cylinder 5 can be made as small as possible, biting of the seal ring 8 into the gap can be prevented, and the sealing performance can be improved.

Furthermore, FIGS. 3, 4, and 5 show the third, fourth, and fifth embodiments. Between the end surface of the piston member on which the annular flange is erected and the end surface of the adjacent piston member, A tilt absorbing portion 18 of the piston member on which the annular flange is erected is provided. As a result, even if an eccentric load from the diaphragm spring 3 acts on the piston member 17, the inclination absorbing portion 18 can further reduce the influence of the inclination on the piston member 16 on which the seal ring 8 is mounted. The relationship between D2 of the piston member 16 and the outer diameter D1 of the piston member 17 is the same as in the embodiment of FIG.

A specific embodiment of the tilt absorber will be described below.

In FIG. 3, the inner end 17a of the piston member 17 on which the above-mentioned annular flange is erected is the end surface 1 having an arcuate cross section.
8a, and this arcuate end face serves as a tilt absorbing portion. In FIG. 3, since the end face of the outer end 16b of the piston member 16 to which the seal ring 8 is attached is made flat, the inclination absorption of the arcuate end face 18a of the piston member 17 contacting the flat face is absorbed. Sex becomes more certain.

Further, the one shown in FIG.
Is a piston member 17 on which the annular flange 15 is erected.
It is formed of a cushioning material 18b such as rubber, spring, resin or the like, which is interposed between the end surface of the piston and the end surface of the adjacent piston member 16. In FIG. 4, one end of this cushioning material 18b is fixed in a circumferential recess 19 formed on the end surface of the inner piston member 16, and the other end is in contact with the end surface of the outer piston member 17. With this cushioning material 18b, it is possible to reliably cope with an eccentric load from the diaphragm spring 3 in all directions.

Further, in FIG. 5, the inclination absorbing portion 18 is formed by a ball 18c interposed between the end surface of the piston member on which the annular flange 15 is erected and the end surface of the adjacent piston member. Has been done. The balls 18c are formed in the circumferential recesses 20 and 2 formed on the end surfaces of the piston members 16 and 17, respectively.
Held within 1. By using this ball,
The inclination of the piston members 16 and 17 is more reliably absorbed.

Furthermore, FIG. 6 shows a sixth embodiment. At the time of replacement such as repair of the release bearing 9, the piston member 17 on which the annular flange 15 is erected is removed together with the bearing 9, but at this time, the adjacent piston member 16 is in a free state in the axial direction, so in the worst case In some cases, the oil may escape from the hydraulic chamber 12 in the axial direction. If the piston member 16 becomes free in the direction of coming out, there is a possibility that the hydraulic oil in the hydraulic chamber 12 may leak or external air may enter the hydraulic oil, which is a problem. Furthermore, when the release bearing 9 or the like is replaced, it moves freely and an unexpected load acts on the piston member 16, and the outer peripheral surface 5a of the inner cylinder 5 and the inner peripheral surface 6a of the outer cylinder 6 are scratched, resulting in a hydraulic oil. Cause leakage. Therefore, when the piston member 17 on which the annular flange 15 is erected is attached or detached, the slip-out prevention mechanism 19 is formed in the inner cylinder 5 so that the adjacent piston member 16 does not move freely in the axial direction.

As one specific configuration of the slip-out preventing mechanism 19, a radial through hole 19a formed in the inner cylinder 5 and a projecting member 19b projecting from the inner diameter side of the through hole 19a to the outer diameter side are provided. Adjacent piston member 16
And a recessed step portion 19c formed on the inner peripheral surface thereof and into which the protruding member 19b is inserted. Further, although the concave step portion 19c formed on the piston member 16 is formed by the circumferential step portion formed on the inner peripheral surface of the corner portion of the piston member 16 in the embodiment, it is formed on the inner peripheral surface of the piston member 16. It may be a concave portion formed at an arbitrary position, and may be at least a size into which the protruding member 19b can be inserted. Therefore, the recessed step portion 19c may be a circumferential step portion, or may be formed on a part of the inner peripheral surface of the piston member 16. However, the shape of the recessed stepped portion 19c is formed on the inner peripheral surface of the corner portion of the piston member 16 in view of the ease of alignment with the projecting member 19b, as described in the operation of the slip-out preventing mechanism 19 described later. The circumferential step is optimal.

Next, the operation of the slip-out prevention mechanism 19 will be described. When repairing the release bearing 9, the hydraulic clutch disengagement device is disassembled in the following procedure. First, the positions of the through hole 19a of the inner cylinder 5 and the recessed step portion 19c of the piston member 16 are aligned. Then, in this state, the projecting member 19b, which is a jig, is inserted into the through hole 19a from the inner diameter side of the through hole 19a of the inner cylinder 5 so as to project toward the outer diameter side of the inner cylinder 5, and the piston member 16
It is inserted into the recessed stepped portion 19c to restrict the outward movement of the piston member 16 in the axial direction. Then, the boot 11 is removed from the annular flange 15, and the piston member 17 adjacent to the annular flange 15 is removed with the release bearing 9 mounted. When assembling, reverse the above procedure.

During this detaching operation, the adjacent piston member 16 is prevented from coming out in the axial direction by the coming-out preventing mechanism 19, so that the leakage of hydraulic oil from the hydraulic chamber 12 and the actuation of air are performed. Invasion of oil is prevented.
Further, since the piston member 16 is restricted from moving in the axial direction, the outer peripheral surface 5a of the inner cylinder 5 and the inner peripheral surface 6a of the outer cylinder 6 are less likely to be damaged by an unexpected load, and the hydraulic oil does not leak. Is prevented.

[0046]

According to the first aspect of the present invention, the cylindrical piston is axially displaceably inserted from one end into the hydraulic chamber, and the inner cylinder and the outer that are disposed on one end of the piston to form the hydraulic chamber. Hydraulic clutch disengagement having a seal ring having a seal lip that is brought into contact with the cylinder, and a release bearing that is attached to an annular flange that is erected on the other end side of the piston and that abuts against a clutch operating member. In the device, the piston is
It is divided into a plurality of piston members at an arbitrary axial position between the position where the annular flange is erected and the position where the seal ring is mounted. Therefore, even if an eccentric load from the diaphragm spring acts on the piston through the release bearing during operation of the hydraulic clutch disengagement device, this eccentric load acts only on the piston member on the release bearing mounting side, and the seal ring is mounted. The piston member is prevented from acting and tilting does not occur. Therefore, the change in the contact pressure of the lip of the seal ring is prevented, the uneven wear due to the reciprocal movement of the seal ring due to the reciprocating movement of the piston is prevented, and there is no risk of oil leakage.

According to the second aspect of the present invention, among the plurality of piston members, the outer diameter of the piston member on which the annular flange is erected is smaller than the outer diameter of the other piston member. Even if an unbalanced load from the spring acts on the outer piston member and causes tilting, the gap between the outer diameter surface of this piston member and the inner peripheral surface of the outer cylinder is large, and the end portion of the outer piston member has an outer cylinder. The contact with the inner peripheral surface of the is more reliably prevented. As a result, the inner peripheral surface of the outer cylinder is not damaged, and there is no risk of oil leakage.

Furthermore, the inventions of claims 3 to 6 are
Among the plurality of piston members, between the end surface of the piston member on which the annular flange is erected and the end surface of the adjacent piston member,
Since the tilt absorbing portion of the piston member in which the annular flange is erected is provided, even if an unbalanced load from the diaphragm spring acts on the outer piston member, the tilt absorbing portion causes the piston with the seal ring to be mounted. The influence of the tilt on the member can be further reduced.

Furthermore, the invention of claims 7 to 9 is
Of the multiple piston members, when the piston member in which the annular flange is erected is attached or detached, a slip-out prevention mechanism that prevents axial displacement of the adjacent piston member is formed in the inner cylinder, so leakage of hydraulic oil from the hydraulic chamber And air is prevented from entering the hydraulic oil.

[Brief description of drawings]

FIG. 1 is a sectional view of a hydraulic clutch disengagement device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a hydraulic clutch disconnecting device according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a hydraulic clutch disconnecting device according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a hydraulic clutch disconnecting device according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a hydraulic clutch disconnecting device according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view of a hydraulic clutch disengagement device according to a sixth embodiment of the present invention.

FIG. 7 is a sectional view of a conventional hydraulic clutch disengagement device.

[Explanation of symbols]

1 input axis 2 clutch housing 3 diaphragm spring 4 Hydraulic clutch disengagement device 5 Inner cylinder 6 Outer cylinder 7 pistons 8 seal ring 9 Release bearing 10 coil spring 11 boots 12 Hydraulic chamber 16 Piston member 17 Piston member 18 Tilt absorber 19 Fall-out prevention mechanism

Claims (9)

[Claims] 1. An inner cylinder that is fixedly arranged and has an input shaft of a transmission inserted through the inner periphery thereof; an outer cylinder that is fixedly arranged so as to form a hydraulic chamber having an annular space on the outer periphery of the inner cylinder; A seal having a cylindrical piston that is axially displaceably inserted into the hydraulic chamber from one end side, and a seal lip that is disposed on one end side of the piston and is in contact with the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder. In a hydraulic clutch disengagement device having a ring and a release bearing attached to an annular flange erected on the other end side of the piston and abutting against a clutch operating member, the piston has an annular flange. Characterized by being divided into multiple piston members at arbitrary axial positions between the standing position and the position where the seal ring is mounted Hydraulic clutch disengagement device. 2. The piston member having a plurality of piston members, on which the annular flange is erected, has an outer diameter smaller than outer diameters of other piston members. Hydraulic clutch release device. 3. A tilt absorbing portion of a piston member, on which the annular flange is erected, is provided between an end surface of the piston member, on which the annular flange is erected, and an end surface of an adjacent piston member, of the plurality of piston members. The hydraulic clutch disengagement device according to claim 1 or 2, wherein. 4. The hydraulic clutch disengagement device according to claim 3, wherein the inclination absorbing portion is an end surface of the piston member on which the annular flange is erected and which has an arcuate cross section. 5. The cushioning member interposed between the end surface of the piston member on which the annular flange is erected and the end surface of an adjacent piston member, is formed in the inclination absorbing portion. The hydraulic clutch disengagement device described. 6. The tilt absorbing portion is a ball interposed between an end surface of a piston member on which the annular flange is erected and an end surface of an adjacent piston member. Hydraulic clutch release device. 7. An inner cylinder is provided with a slip-out prevention mechanism for preventing axial displacement of an adjacent piston member when the piston member, out of a plurality of piston members, on which the annular flange is erected is attached or detached. The hydraulic clutch disengagement device according to claim 1. 8. The slip-out preventing mechanism is formed on a radial through hole formed in an inner cylinder, a projecting member projecting from an inner diameter side of the through hole to an outer diameter side, and an inner peripheral surface of an adjacent piston member. The hydraulic clutch disengagement device according to claim 7, wherein the hydraulic clutch disengagement device is formed of a concave step portion into which the protruding member is inserted. 9. The concave step portion of the adjacent piston member is a circumferential step portion formed on an inner peripheral surface of a corner portion of an end surface of the piston member side on which the annular flange is erected. The hydraulic clutch disengagement device described in 1.