CN114483812A

CN114483812A - Clutch actuating device

Info

Publication number: CN114483812A
Application number: CN202011411421.5A
Authority: CN
Inventors: 钟宏鸣; 方晓瑜; 陈树亮; 周然; 李晓明; 冯晓明
Original assignee: Knorr Bremse Braking Systems For Commercial Vehicles Dalian Co Ltd; Knorr Bremse Commercial Vehicles Systems Shanghai Co Ltd
Current assignee: Knorr Bremse Braking Systems For Commercial Vehicles Dalian Co Ltd; Knorr Bremse Commercial Vehicles Systems Shanghai Co Ltd
Priority date: 2020-11-11
Filing date: 2020-12-04
Publication date: 2022-05-13

Abstract

The invention relates to a clutch actuating device, comprising an axially displaceable first piston (1), a transmission part in driving connection with a clutch, and a wear compensation mechanism drivingly located at least partially between the first piston and the transmission part, the wear compensation mechanism comprising a first part coupled for axial movement with the first piston and a second part coupled for axial movement with the transmission part (2), the wear compensation mechanism being configured to be switchable between a locked state in which the first part is radially pressed against the second part to frictionally lock the first and second parts axially relative to each other to enable axial movement to be transmitted between the first piston and the transmission part; in the unlocked state, the second part is axially movable relative to the first part to adjust the axial position of the transmission part relative to the first piston in the engaged state of the clutch to follow the degree of wear of the clutch.

Description

Clutch actuating device

Technical Field

The present invention relates to a clutch actuating device.

Background

Clutch actuating devices are applied to vehicles for operating clutches. Typically, the clutch is arranged to be biased to a fully engaged state, i.e. the clutch will always return to its fully engaged state once the external operating force is released. In practice, wear of the clutch is inevitably present during use, which makes it desirable for the clutch actuator to compensate for wear following the degree of wear of the clutch. Otherwise, the clutch actuation device may cause the clutch to become stuck during engagement and fail to reach a fully engaged state.

Accordingly, it is desirable to provide a clutch actuation device that is compact and easy to manufacture that can adaptively compensate for clutch wear.

Disclosure of Invention

The object of the invention is achieved by providing a clutch actuating device comprising a housing, a first piston axially displaceable in the housing, a transmission member in driving connection with the clutch, and a wear compensation mechanism drivingly located at least partly between the first piston and the transmission member, the wear compensation mechanism comprising at least one first part coupled with the first piston for axial movement and a second part coupled with the transmission member for axial movement, the wear compensation mechanism being configured to be switchable between a locked state in which the first part is radially pressed against the second part to enable the first and second parts to be frictionally locked in axial direction with respect to each other to transmit axial movement between the first piston and the transmission member; in the unlocked state, the second part is axially movable relative to the first part to adjust the axial position of the transmission part relative to the first piston in the engaged state of the clutch to follow the degree of wear of the clutch.

According to an alternative embodiment, the wear-compensating mechanism is switched to a locked state by loading the first part with fluid pressure and to an unlocked state by unloading fluid pressure from the first part.

According to an alternative embodiment, the wear compensation mechanism comprises at least one cylinder-piston assembly comprising a cylinder and a second piston guided at least partially in the cylinder, the first part being configured as the second piston and the second part being configured as an axially extending bushing, the cylinder-piston assembly being positioned and oriented such that the second piston slides radially towards or away from the bushing.

According to an alternative embodiment, the first piston slides within the housing to define a chamber for receiving the pressurized fluid, said chamber being located on the opposite side of the first piston from the cylinder-piston assembly and being in fluid communication with the cylinder, in particular by means of a fluid passage passing through the first piston.

According to an alternative embodiment, the cylinder-piston assembly further comprises a fluid opening provided in the cylinder, a sealing head for opening or closing the fluid opening, and a spool for carrying the sealing head, the spool being capable of being displaced by pressurized fluid when the pressurized fluid is introduced into the cylinder, so that the sealing head opens the fluid opening and returns to a position where the sealing head closes the fluid opening under the biasing force of the biasing member when the pressurized fluid in the cylinder is drained away.

According to an alternative embodiment, the wear-compensating mechanism comprises at least two cylinder-piston assemblies, which are distributed around the bushing.

According to an alternative embodiment, the valve slide and the second piston are arranged in line with one another along the cylinder within the cylinder, wherein the valve slide is at least partially received within the second piston for guided movement within the second piston, wherein the biasing member is configured as a compression spring, one end of which acts on the valve slide or the cylinder and the other end acts on the second piston.

According to an alternative embodiment, the second piston comprises a piston body and a pressure plate attached at a radially inner end of the piston body, wherein the piston body, when loaded by fluid pressure, transfers the fluid load to the pressure plate to frictionally lock the pressure plate with the sleeve in the axial direction.

According to an alternative embodiment, the sleeve and the pressure plate are coupled to each other by a spline structure, in which teeth and grooves each extend axially on a respective one of the sleeve and the pressure plate.

According to an alternative embodiment, the first piston has an abutment axially abutting the pressure plate to directly transfer the axial load between the first piston and the pressure plate.

According to an alternative embodiment, the housing comprises an inner annular sleeve projecting axially from its end wall towards the interior of the housing, the first piston and the second member being slidably mounted on the inner annular sleeve; or the housing comprises an inner annular sleeve and an outer annular sleeve axially projecting from its end wall towards the interior of the housing, said outer annular sleeve being located radially outwardly of said inner annular sleeve, the first piston being slidably mounted on the outer annular sleeve and the second member being slidably mounted on the inner annular sleeve.

Further advantages and advantageous embodiments of the inventive subject matter are apparent from the description, the drawings and the claims.

Drawings

Further features and advantages of the present invention will be further elucidated by the following detailed description of an embodiment thereof, with reference to the accompanying drawings. The attached drawings are as follows:

fig. 1 shows a longitudinal section through a clutch actuating device according to a first embodiment of the invention; ,

FIG. 2 shows a partial transverse cross-sectional view of a clutch actuation device according to a first embodiment of the present invention;

FIG. 3 shows a partial longitudinal perspective cut-away view of a clutch actuation device according to a second embodiment of the present invention;

fig. 4 shows a longitudinal section through a clutch actuating device according to a third embodiment of the invention;

FIG. 5 shows a partial transverse cross-sectional view of a clutch actuation device according to a third embodiment of the present invention; and is

Fig. 6 shows a schematic configuration diagram of a clutch actuating apparatus according to a fourth embodiment of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantageous technical effects of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and exemplary embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of the invention. In the drawings, the same or similar reference numerals refer to the same or equivalent parts.

Fig. 1 shows a longitudinal sectional view of a clutch actuating device according to a first embodiment of the present invention, and fig. 2 shows a partial transverse sectional view of the clutch actuating device according to the first embodiment of the present invention. As shown in fig. 1-2, the clutch actuator 100 includes a housing 4, a first piston 1 axially slidable within the housing 4, a transmission member 2 drivingly connected to a clutch (not shown), and a wear compensation mechanism 3 drivingly positioned at least partially between the first piston 1 and the transmission member 2.

The housing 4 is designed as a cylinder, in particular a cylindrical cylinder, which is open at one end and thus comprises a circumferential side wall 41 and an end wall 42 connected to the circumferential side wall 41. The circumferential side wall 41 and the end wall 42 may, for example, be integrally formed. The end wall 42 is provided with a housing port 47 for fluid ingress and egress. The end wall 42 extends axially out of the bridge tube 45 at the location of the housing aperture 47, in particular from an aperture edge of the housing aperture 47. In particular, the bridge tube 45 is formed integrally with the housing 4. Further, an open end of the housing 4 opposite the end wall 42 is mounted with an end cap 5 and a dust cover 6.

The housing 4 also has an inner annular sleeve 43 projecting axially from the centre of the end wall 42 towards the interior of the housing, and a sleeve 32, which will be explained in more detail below, is slidably mounted on the inner annular sleeve 43. Further, the housing 4 has an annular outer ring 44 projecting from the end wall 42 in the axial direction on the radially outer side of the inner ring 43, and the inner peripheral side of the first piston 1 is slidably supported on the outer ring 44.

The first piston 1 includes a piston disc 13 and a flange portion 14 projecting from a circumferential edge of the piston disc 13 in the axial direction. A chamber 7 is defined between the first piston 1 and the housing 4. When the chamber 7 is vented with pressurized fluid, the first piston 1 may be pushed by the pressurized fluid to perform an axial displacement along the inner wall of the housing 4.

In order to ensure the fluid tightness of the chamber 7, a first sealing structure 11 is provided between the first piston 1 and the circumferential side wall 41, and a second sealing structure 12 is provided between the first piston 1 and the outer ring sleeve 44. According to an example, the first and/or

second sealing structure

11, 12 is configured as a sealing ring.

The wear-compensating mechanism 3 comprises at least one first part 31 coupled to the first piston 1 in an axial movement and a second part 32 coupled to the transmission part 2 in an axial movement. The wear-compensating mechanism 3 is configured to be switchable between a locked state and an unlocked state. In the locked state, the first part 31 is pressed radially against the second part 32, so that the first and

second parts

31, 32 frictionally engage each other to be able to transmit axial movements between the first piston 1 and the transmission part 2; in the unlocked state, the second part 32 is axially movable relative to the first part 31 in order to be able to adjust the axial position of the transmission part 2 relative to the first piston 1 in the engaged state of the clutch to follow the degree of wear of the clutch.

Further, the wear-compensating mechanism 3 is switched to the locked state by loading the first member 31 with the fluid pressure, and the wear-compensating mechanism 3 is switched to the unlocked state by unloading the fluid pressure on the first member 31.

Specifically, the second member 32 is configured as a sleeve 32 having a substantially cylindrical shape, in particular, a cylindrical shape. The hub 32 is slidably mounted on the inner collar 43 to slide along the inner collar 43 during operation of the device 100. The outer collar 44 and the inner collar 43 define an annular recess 8 therebetween, and the recess 8 is accessible by the sleeve 32. In this way, the sleeve 32 has a greater axial travel, so that wear of the clutch can be compensated for to a greater extent.

The wear-compensating mechanism 3 comprises at least one, in particular at least two, for example three, cylinder-piston assemblies 30 distributed circumferentially around a sleeve 32, as best shown in fig. 5. These cylinder-piston assemblies 30 may be, for example, equally angularly spaced. The cylinder-piston assembly 30 comprises a cylinder 33 and a second piston sliding within the cylinder 33 as the first component 31 described above. Each cylinder-piston assembly 30 is oriented such that the reciprocating movement of its second piston 31 is performed in the radial direction of the device 100. When the cylinder 33 is charged with pressurized fluid, the pressurized fluid exerts a force on the second piston 31 so that the second piston 31 is pressed tightly radially inward against the outer circumferential surface of the sleeve 32, thereby frictionally locking with the sleeve 32.

Illustratively, the cylinder-piston assembly 30 is fixed to the first piston 1 after being preassembled, for example by means of bolts 55 (see fig. 2).

In the exemplary embodiment, the second piston 31 comprises a piston sleeve 311 which slides guided on an inner side wall of the cylinder 33 and a piston rod 312 which is at least partially located within the piston sleeve 311 and is rigidly connected to the piston sleeve 311 (see fig. 4). The fluid in the cylinder 33, if any, will urge the piston sleeve 311 and thus the piston rod 312 radially inwardly, thereby causing the inner end surface 3121 of the piston rod 312 to abut against the boss 32.

Illustratively, in an unloaded state, the piston rod 312 extends at least partially from the cylinder 33.

Illustratively, the piston sleeve 311 is provided with an outer flange 3111 at its radially outer end (see fig. 4). The outer flange 3111 serves on the one hand to carry the second spring 36 and on the other hand as a force input surface for the pressurized fluid. A working chamber 34 for receiving pressurized fluid is defined between the cylinder 33 and the piston sleeve 311 above the outer flange 3111.

For example, the inner end surface 3121 may be designed to have a shape that fits with the outer peripheral surface of the boss 32. In the case where the boss 32 is cylindrical, the shape of the inner end surface 3121 may be a circular arc surface having a radius of curvature substantially corresponding to the radius of curvature of the cylindrical shape of the boss 32.

The cylinder 33 is in fluid communication with the chamber 7. For this purpose, the cylinder 33 is provided with a first fluid opening 331 and the first piston 1 is provided with a first fluid passage 15 through the first piston 1 leading to the chamber 7, wherein the first fluid opening 331 and the first fluid passage 15 are in fluid communication with each other in an aligned manner. More particularly, the cylinder 33 defines, in particular at its radially outer end, a fluid passage 334 extending axially in the direction of the first piston 1, which fluid passage 334 forms, at its free end, a first fluid opening 331 and, at the other end opposite the free end, a third fluid opening 333 leading to the working chamber 34. The first fluid passage 15 is formed by a short tube 16 axially extending from the piston disc 13 of the first piston 1. In the assembled state, the fluid channel 334 forms a straight and coherent passage with the first fluid passage 15. Thereby, fluid entering the cylinder 33 can enter the chamber 7 via this passage.

The cylinder 33 is further provided with a second fluid opening 332, correspondingly the first piston 1 is provided with a second fluid passage 17. In the assembled state, the second fluid opening 332 and the second fluid passage 17 are in fluid communication with each other in an aligned manner, and further, the second fluid passage 17 is in fluid communication with the housing orifice 47 by being inserted by the bridge tube 45 protruding from the housing 4. In this manner, pressurized fluid from an external fluid source (not shown) may be caused to enter the cylinder 33 via the housing aperture 47, the bridge tube 45, the second fluid passageway 17, and the second fluid opening 332.

Illustratively, a third seal 48 (see FIG. 4) is provided between the bridge tube 45 and the second fluid passageway 17.

Further, the cylinder-piston assembly 30 also includes a valve assembly for connecting or disconnecting fluid communication between the first fluid opening 331 and the second fluid opening 332. The valve assembly is received within the cylinder 33 and includes a sealing head 351 for opening or closing the third fluid opening 333, a valve spool 352 for carrying the sealing head 351, and a second spring 36 for biasing the valve spool 352 toward the third fluid opening 333. The radially outer end of the second spring 36 abuts, in particular is fixed to, the spool 352, while the radially inner end abuts, in particular is fixed to, the outer flange 3111 of the piston sleeve 311.

In the assembled and fluid-unloaded state, the second spring 36, which is a compression spring, on the one hand biases the spool 352 radially outward so that the sealing head 351 loaded on the spool 352 blocks the third fluid opening 333, and on the other hand biases the second piston 31 toward the sleeve 32 so that the second piston 31 is pressed loosely, i.e., with a small pressing force, against the sleeve 32, while an opening gap 39 (see fig. 4) is left between the radially inner end face of the spool 352 and the radially outer end face of the piston rod 312, and a safety gap 38 (see fig. 4) is left between the outer flange 3111 and the inner end disc 3521 of the spool 352. The opening clearance 39 ensures that the spool 352 can perform a radial inward displacement for opening the third fluid openings 333, while the safety clearance 38 ensures that the second spring 36 is not self-locked between the inner end disc 3521 and the outer end disc 3522 of the spool 352.

The distance between the radially outer end surface of the piston rod 312 and the radially inner side surface of the outer flange 3111 of the piston sleeve 311 is larger than the radial dimension of the inner end disc 3521 of the spool 352, and the difference therebetween is substantially equal to the sum of the opening gap 39 and the relief gap 38.

Illustratively, a fourth seal structure is provided between the inner end disc 3521 of the spool 352 and the piston sleeve 311 and/or a fifth seal structure is provided between the piston sleeve 311 and the cylinder 33 (see fig. 4).

The clutch actuator 100 further comprises a first spring 9 biasing the first piston 1 towards the end wall 42. Specifically, the first spring 9 is a pre-compressed spring having one end abutting, in particular fixed, to the first piston 1 and the other end abutting, in particular fixed, to the end cap 5. The biasing action of the first spring 9 ensures that the first piston 1 is always in the initial position abutting the end wall 42 in the clutch engaged state.

The end cap 5 is fitted on the boss 32 in such a manner as to be coupled in axial movement with the boss 32. For this purpose, the end cap 5 is locked to the sleeve 32, for example by means of a clip (not shown). Additionally or alternatively, a first stop member 10 (e.g., a stop ring) may be provided between the sleeve 32 and the radially inner flange 51 of the end cap 5 to limit axial displacement between the sleeve 32 and the end cap 5. For this purpose, the sleeve 32 and/or the end cap 5 is/are provided with a recess for receiving the first stop element 10. Additionally or alternatively, the sleeve 32 is formed with a boss 321, against which boss 321 the radially inner flange 51 of the end cap 5 abuts in the assembled state.

The flange portion 14 of the first piston 1 is formed with a plurality of finger portions 141 that are circumferentially spaced apart on the flange portion 14. Correspondingly, the radially outer flange 52 of the end cap 5 is provided with a plurality of corresponding recesses 521 for receiving the fingers 141. That is, the first piston 1 and the end cap 5 form an interdigitated fit.

According to an example, the above mentioned transmission part 2 is configured as a release bearing. The release bearing 2 is in driving connection with the shaft sleeve 32 by means of the end cap 5, so that the three release bearing 2, end cap 5 and shaft sleeve 32 are coupled in an axial movement. Illustratively, the release bearing 2 rests with its axial end on the end cap 5 and defines with the end cap 5 a slot 21 for receiving the dust cover 6. Further, for example, a second stopper member 23 (e.g., a stopper ring) may be provided between the release bearing 2 and the end cover 5 to restrict relative axial displacement between the release bearing 2 and the end cover 5. For this purpose, the release bearing 2 and/or the end cap 5 are provided with

further recesses

24, 54 for receiving the second stop element 23.

In one example, the radially outer end of the dust cover 6 is secured to the housing 4, for example by means of bolts 61.

Operation of clutch actuator

1. Initial state

In the initial state, the first piston 1 is pressed against the end wall 42 of the housing 4 by the first spring 9, while the second piston 31 of the cylinder-piston assembly 30 is pressed with a lower pressure against the bushing 32 by the second spring 36. At the same time, the sleeve 32 is in a force-balanced rest state, in which the sleeve 32 is subjected to an axial force from the clutch side, which is input via the release bearing 2 to the left, on the one hand, and from the first spring 9, which is input via the end cap 5 to the right, on the other hand, and there is also a static friction force between the sleeve 32 and the second piston 31 due to the pressing of the second piston 31 against the sleeve 32. The sleeve 32 is in force equilibrium in the axial direction under these three forces.

2. Disengaging procedure of clutch

The pressurized fluid enters the working chamber 34 in the cylinder 33 from the housing bore 47 via the bridge tube 45, the second fluid passage 17, the second fluid opening 332, and then the pressurized fluid in the working chamber 34 exerts a radially inward thrust on the piston sleeve 311 of the second piston 31 to force the piston rod 312 tightly against the outer circumferential surface of the sleeve 32, so that the maximum static friction force between the second piston 31 and the sleeve 32 is sufficiently large.

The pressurized fluid, while exerting a radially inward thrust on the second piston 2, also exerts a radially inward thrust on the valve spool 352, so that the valve spool 352 is also displaced radially inward until the opening gap 39 is eliminated and the sealing head 351 opens the third fluid opening 333, so that the pressurized fluid in the working chamber 34 can enter the chamber 7 via the third fluid opening 333, the fluid passage 334, the first fluid opening 331 and the first fluid through hole 15. The working fluid in the chamber 7 may generate an axial rightward thrust on the first piston 2 for disengaging the clutch.

Since the second piston 31 and the sleeve 32 are friction-locked sufficiently stably by means of the fluid pressure, the first piston 2 can carry the cylinder-piston assembly 30 and thus push the sleeve 32 to the right, thereby further extending the release bearing 2 to effect or assist the release of the clutch.

3. Clutch engagement process

Fluid is vented or relieved from housing port 47, at which time pressurized fluid within chamber 7 will be exhausted from housing port 47 through first fluid throughbore 15, first fluid opening 331 and third fluid opening 333 and past the unsealed sealing head 351 and then via second fluid opening 332, second fluid passage 17 and bridge tube 45. When the pressure in the chamber 7 and the working chamber 34 is relieved, the first piston 1 will return to the initial position under the action of the first spring 9 and the clutch reaction force, and the sealing head 351 will re-close the third fluid opening 333 under the action of the second spring 36.

4. Wear self-adjusting process

In the event of wear of the clutch, the release bearing 2 still needs to follow the clutch further to the left when the first piston 1 has moved to abutment against the end wall 42. At this point the fluid pressure in the chamber 7 and the working chamber 34 has been relieved, so that the second piston 31 only exerts a small pressure on the sleeve 32 and thus the maximum static friction between the second piston 31 and the sleeve 32 is sufficiently small that the reaction force from the clutch side, which is input by the release bearing 2, can overcome this friction force and push the sleeve 32 further to the left a distance relative to the stationary first and

second pistons

1,31 until a new force equilibrium position is reached.

Thus, the clutch actuating apparatus according to the present invention can perform self-adjustment following the degree of wear of the clutch each time the clutch is closed.

Fig. 3 shows a partial longitudinal perspective sectional view of a clutch actuation device 100' according to a second embodiment of the invention. In this embodiment, most of the features and details of the clutch actuation device 100' are the same as the clutch actuation device 100 shown in fig. 1-2 and will not be described again here. Only the differences of the clutch actuator 100' with respect to the clutch actuator 100 will be explained below.

In this embodiment, the outer collar 44 is omitted and the empty slot 8 is thereby eliminated. The first piston 1 is not fitted to the outer ring 44 as in the first embodiment, but to the inner ring 43. In this way, although the wear adjustable stroke for the sleeve 32 is shortened, the effective active area of the first piston 2 is increased.

Fig. 4 shows a longitudinal section through a clutch actuating device 100 "according to a third embodiment of the invention, and fig. 5 shows a partial transverse section through a clutch actuating device 100" according to a third embodiment of the invention. In this embodiment, most of the features and details of the clutch actuation device 100 "are the same as the clutch actuation device 100 shown in fig. 1-2 and will not be described again here. Only the differences of the clutch actuator 100 "with respect to the clutch actuator 100 are explained below.

First, as in the second embodiment, the outer race 44 and the empty slot 8 of the clutch actuation device 100 "are eliminated.

Additionally, the second piston 31 is provided with a pressure plate 37 at the radially inner end towards the shaft sleeve 32. The pressure plate 37 may be arranged outside the cylinder 33 on the radially inner side of the cylinder 33. When the second piston 31 is acted upon by fluid pressure, the second piston 31 rests with its pressure plate 37 against the outer circumferential surface of the sleeve 32 and is thus frictionally locked with the sleeve 32. Thus, the piston rod 312 of the second piston 31 is no longer in direct contact with the sleeve 32 as in the first and second embodiments. When the second piston 31 is not loaded with fluid pressure, relative axial displacement between the pressure plate 37 and the sleeve 32 can be performed.

Furthermore, with reference to fig. 5, the pressure plates 37 associated with each cylinder-piston assembly 30 extend in sections over the circumference, it being possible for adjacent pressure plates 37 to have an in particular approximately constant angular gap between them. Also, at least one protrusion 371 is formed, for example integrally, on the inner circumferential side of the pressure plate 37 facing the bushing 32, while a groove 323 for receiving at least one of the protrusions 371 is correspondingly formed on the outer circumferential side of the bushing 32 facing the pressure plate 37, wherein the protrusion 371 and the groove 323 may form a form fit. Illustratively, the protrusion 371 and the groove 323 may be in the form of a V-shape or an inverted V-shape, as viewed in the axial direction.

Additionally or alternatively, a receptacle 372 is formed on the outer circumferential side of the pressure plate 37 facing the second piston 31, at least a part of the second piston 31, in particular at least a part of the section of the piston rod 312 projecting from the cylinder 33, being received in the receptacle 372.

Further, the first piston 1 is configured to be in axial abutment with the pressure plate 37, so as to transmit the axial load applied by the pressurized fluid to the first piston 1 directly to the pressure plate 37 and further to the sleeve 32 which is frictionally engaged with the pressure plate 37. In one example, the first piston 1 is formed with a projection 18 which projects from the piston disk 13, the projection 18 extending axially until it comes into abutment with the pressure plate 37. In this way, the load transmission path is changed such that the output force of the first piston 1 is mainly transmitted through the projection 18, thereby preventing the cylinder-piston assembly 30 from being subjected to heavy load, thereby improving the transmission and stability of the output force.

Furthermore, the cylinder 33 is integrated with the first piston 1, in particular integrally formed with the first piston 1. In this case, the first fluid passage 19 for communicating the working chamber 34 of the cylinder 33 with the chamber 7 is formed integrally with the cylinder 33 and the first piston 1, and is no longer formed by the butt joint of the short tube 16 of the first piston 1 and the fluid passage 334 of the cylinder 33 as in the first and second embodiments. Likewise, the second fluid passage 29 for communicating the working chamber 34 with the bridge tube 45 is also formed integrally with the cylinder block 33 and the first piston 1, and is no longer formed by the abutment of the second fluid passage 17 of the first piston 1 and the second fluid opening 332 of the cylinder block 33 as in the first and second embodiments. In this way, the connecting bolts 55 between the cylinder-piston assembly 30 and the first piston 1 are eliminated, increasing the structural stability.

Fig. 6 shows a schematic block diagram of a clutch actuating device 100' ″ according to a fourth embodiment of the present invention. The outer frame in this figure does not form part of the device 100' ″. In this embodiment, most of the features and details of the clutch actuation device 100 "are the same as the clutch actuation device 100 shown in fig. 1-2 and will not be described again here. Only the differences of the clutch actuator 100' ″ with respect to the clutch actuator 100 will be explained below.

In the initial state, the second piston 31 is pressed against the sleeve 32 under the pre-pressure of the second spring 36, in order to limit the freedom of radial movement of the second piston 31 at least to some extent. Furthermore, the radially extending structure of the cylinder 33, for example the cylinder wall bounding the working chamber 34, limits the freedom of axial movement of the second piston 31.

Also, the bridge tube 45 and the second fluid passage 29 for communicating the bridge tube 45 with the working chamber 34 (specifically, the second fluid opening 332 of the cylinder 33 and the second fluid passage 17 of the first piston 1, see fig. 1 and 4) are eliminated. Alternatively, the working chamber 34 feeds or discharges pressurized fluid from or to the chamber 7 through the first fluid passage 19. Specifically, when it is desired to disengage the clutch, pressurized fluid is first communicated into chamber 7 and then from chamber 7 into working chamber 34 via first fluid passage 19, thereby frictionally locking second piston 31 to sleeve 32 while first piston 1 is urged rightward by the pressurized fluid, thereby transmitting the axial output force of chamber 7 through sleeve 32 to the clutch end. When the clutch is engaged, the fluid in the chamber 7 is discharged outwards and the fluid in the working chamber 34 is also discharged outwards via the chamber 7, so that the first piston 1 and the sleeve 32 are retracted to the initial position under the action of the first spring and the clutch thrust, while the fluid pressure in the working chamber 34 is unloaded, and thus the maximum static friction force between the second piston 31 and the sleeve 32 is small, so that the sleeve 32 can freely continue to retract under the action of the clutch thrust to compensate for the wear of the clutch.

It should be noted here that the geometric form of the second piston 31 is not limited to the cylindrical block form shown in fig. 6, but that other suitable shapes, such as a hollow cylinder, a T-shaped cross-section, an I-shaped cross-section, are also possible as will occur to those skilled in the art.

According to an exemplary embodiment of the invention, the pressurized fluid may be a pressurized gas or a pressurized liquid.

The clutch actuating device according to the present invention is applicable to a clutch biased to a fully engaged state, in which the clutch is always returned to its fully engaged state once an external operating force is released.

Although some embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. The appended claims and their equivalents are intended to cover all such modifications, substitutions and changes as fall within the true scope and spirit of the invention.

Claims

1. Clutch actuation device (100, 100') comprising a housing (4), a first piston (1) axially displaceable within the housing (4), a transmission part (2) in driving connection with a clutch, and a wear compensation mechanism (3) drivingly located at least partially between the first piston (1) and the transmission part (2), the wear compensation mechanism comprises at least one first part coupled with the first piston (1) in an axial movement and a second part coupled with the transmission part (2) in an axial movement, the wear compensation mechanism is configured to be switchable between a locked state and an unlocked state, in the locked state, the first part is pressed radially against the second part, so that the first part and the second part are frictionally locked in axial direction with respect to each other, so as to be able to transmit axial movements between the first piston (1) and said transmission member (2); in the unlocked state, the second part is axially movable relative to the first part in order to be able to adjust the axial position of the transmission part (2) relative to the first piston (1) in the engaged state of the clutch to follow the degree of wear of the clutch.

2. Clutch actuation device (100,100 ', 100 ", 100"') according to claim 1,

-the wear compensating mechanism (3) is transferred into a locked state by loading the first part with fluid pressure, -the wear compensating mechanism (3) is transferred into an unlocked state by unloading the fluid pressure on the first part.

3. Clutch actuation device (100,100 ', 100 ", 100"') according to claim 2,

the wear compensation mechanism (3) comprises at least one cylinder-piston assembly (30) comprising a cylinder (33) and a second piston (31) guidably slidable in the cylinder (33), the first part being configured as the second piston (31) and the second part being configured as a sleeve (32) extending in an axial direction, the cylinder-piston assembly (30) being positioned and oriented such that the second piston (31) slides radially towards or away from the sleeve (32).

4. Clutch actuation device (100,100 ', 100 ", 100"') according to claim 3,

the first piston (1) slides within the housing (4) to define a chamber (7) for receiving a pressurized fluid, said chamber (7) being located on the opposite side of the first piston (1) from the cylinder-piston assembly (30) and being in fluid communication with the cylinder (33), in particular with the cylinder (33) by means of fluid channels (15,19) passing through the first piston (1).

5. Clutch actuation device (100,100 ', 100 ", 100"') according to claim 3 or 4,

the cylinder-piston assembly (30) further comprises a fluid opening (331,333) opening into the cylinder (33), a sealing head (351) for opening or closing the fluid opening, and a valve spool (352) carrying the sealing head (351), the valve spool being actuable to move by the pressurised fluid when the pressurised fluid is introduced into the cylinder (33) so that the sealing head (351) opens the fluid opening and returns under the biasing force of the biasing member (36) to the following positions when the pressurised fluid within the cylinder is displaced: in this position, the sealing head (351) closes the fluid opening; and/or

The wear compensation device (3) comprises at least two cylinder-piston assemblies (30), which cylinder-piston assemblies (30) are distributed around the shaft sleeve (32).

6. Clutch actuation device (100,100 ', 100 ", 100"') according to claim 5,

the valve spool (352) and the second piston (31) are arranged in alignment with each other along the cylinder (33) within the cylinder (33), wherein the valve spool (352) is at least partially received within the second piston (31) for guided movement within the second piston (31), wherein the biasing means is configured as a compression spring, one end of which acts on the valve spool (352) and the other end acts on the second piston (31).

7. Clutch actuation device (100,100 ', 100 ", 100"') according to any of claims 3 to 6,

the second piston (31) comprises a piston body (311,312) and a pressure plate (37) attached at a radially inner end of the piston body, wherein the piston body, when loaded by fluid pressure, transfers the fluid pressure load to the pressure plate (37) to frictionally lock the pressure plate (37) with the sleeve (32) in the axial direction.

8. Clutch actuation device (100,100 ', 100 ", 100"') according to claim 7,

the sleeve (32) and the pressure plate (37) are engaged with each other by a spline structure in which a tooth portion (371) and a groove portion (323) each extend in the axial direction on a corresponding one of the sleeve (32) and the pressure plate (37).

9. Clutch actuation device (100,100 ', 100 ", 100"') according to claim 7 or 8,

the first piston (1) has an abutment (18) that axially abuts the pressure plate (37) and directly transmits an axial load between the first piston (1) and the pressure plate (37).

10. Clutch actuation device (100,100 ', 100 ", 100"') according to any one of the preceding claims,

the housing (4) comprises an inner annular sleeve (43) projecting axially from its end wall (42) towards the interior of the housing, the first piston (1) and the second part being slidably mounted on the inner annular sleeve (43); or

The housing (4) comprises an inner annular sleeve (43) and an outer annular sleeve (44) projecting axially from its end wall (42) towards the interior of the housing, said outer annular sleeve being located radially outwardly of said inner annular sleeve, the first piston (1) being slidably mounted on the outer annular sleeve (44) and the second member being slidably mounted on the inner annular sleeve (43).