GB2347722A - Clutch actuator having at least one inner bearing ring connected to a diaphragm spring - Google Patents

Abstract

A telescoping clutch actuator 30 comprises a first module 32 supported on cutch casing 14 by a first roller bearing 64 and a second module 34 which is axially displaceable relative to the first module 32 and has a second roller bearing 74 that acts via an inner bearing ring 80 on a diaphragm spring 18. An outer bearing ring 66 of the first roller bearing 64 is connected to the first module 32 while an outer bearing ring 76 of second roller bearing is connected to the second module 34. A hydraulic chamber 60 is formed by external wall regions 52, 42 surrounding internal wall regions 38, 44 of each of the first and second modules 32, 34 and each of the external wall regions 52, 42 are axially movable with respect to one another while each of the internal wall regions 38, 44 are displaceable relative to each other. Seals are provided between the wall regions 52, 42, 38, 44 and the first roller bearing 64 axially overlaps the chamber 60 which is supplied with fluid controlled by a pressure balance valve 62.

Description

2347722 FRICTZON CLUTCH The present invention relates to a friction clutch

and to modular arrangements therefor.

A friction clutch is known, for example, from DE 42 08 906 Al. In this known clutch a diaphragm spring is loaded by a pressure fluid actuating arrangement for carrying out the clutch engagement or disengagement processes. The pressure fluid actuating arrangement is a telescopic unit with a first module which is supported axially via a first bearing arrangement on the stationary i.e. non-rotatable clutch casing and a second module which is displaceable axially with respect to the first module via a second bearing arrangement for loading the spring. The first and the second modules define a fluid chamber into which a working fluid can be introduced to produce the axial relative movement between the first and the second modules. The bearing arrangements each comprise a radially external bearing ring, a radially internal bearing ring and a plurality of bearing bodies or rolling elements between the radially external and the radially internal bearing rings.

With this known friction clutch, the support of the telescopic unit on the casing on the one hand and the action thereof on a diaphragm spring on the other hand enables the axial forces occurring during the performance of disengagement processes to be absorbed completely within the clutch and prevents external components such as, for example, bearing arrangements of a crankshaft or the like from being loaded. The first module in the form of an external cylinder engages with its leading end, in other words the end region close to the casing, in the radially internal bearing ring of the first bearing arrangement, and the radially external bearing ring of this 2 bearing arrangement is then supported axially on the casing. The first module also engages in the radially internal bearing ring of the other of the bearing arrangements, of which the radially external bearing ring acts on the diaphragm spring with a pulling movement for carrying out disengagement processes.

Starting from this state of the art, it is an object of the present invention to provide a friction clutch, in particular a motor vehicle friction clutch, with which increased reliability of operation and reduced wear can be achieved in the region of the axial support or of the axial action of the various modules on the respectively associated components.

In one aspect the invention provides a friction clutch comprising an energy store, which is operated by a pressure fluid actuating arrangement for carrying out clutch engagement or disengagement processest wherein the pressure fluid actuating arrangement is a telescopic unit with a first module supported axially via a first bearing arrangement on a component which is axially substantially stationary, and a second module which is displaceable axially with respect to the first module via a second bearing arrangement for loading the energy store and a fluid chamber into which a working fluid can be introduced to produce the axial relative movement between the first and the second modules, wherein at least one of the bearing arrangements comprises a radially external bearing element, a radially internal bearing element and a plurality of bearing bodies therebetween and the radially external bearing element of the at least one bearing arrangement is connected to one of the first and second modules which is associated with the at least one bearing arrangement.

3 With a friction clutch constructed as described above and according to the invention, in at least one of the bearing arrangements, the interaction of the various bearing elements is reversed in comparison with the state of the art. This has the advantage that, for example, if the at least one bearing arrangement is the bearing arrangement by means of which the energy store, generally designed as a diaphragm spring, is supported, the radially internal bearing element of this bearing arrangement rotates whereas, owing to the rotational decoupling provided by the bearing arrangement, the radially external bearing element is held non-rotatably. This means that, for example, there is substantially no rotation with respect to an inertial system defined by a motor vehicle. This has the significant advantage that substantially no, or significantly reduced, centrifugal forces act on lubricant provided in the internal part of the bearing arrangement, with the further result that the tendency of the lubricant to accumulate in the radially external region of the bearing arrangement is reduced. The lubricant pressure in the radially external region of the bearing arrangement is therefore also reduced with the result that sealing problems, in particular in the radially external region, can be avoided. A contact seal with respect to the radially internal bearing element can easily be created in the radially internal region as there is substantially no tendency for the lubricant to escape from the bearing region, for example due to centrifugal forces. A further advantage is that when the radially internal bearing element rotates, the sliding speeds occurring between the individual bearing bodies and the bearing element or elements are reduced in relation to the configuration known from the state of the art, and this results in similarly reduced wear.

In order to utilise the above-described advantages particularly efficiently, both bearing arrangements preferably 4 have the same construction with inner and outer elements or rings and bearing bodies such as balls therebetween and the radially external bearing element of the first bearing arrangement is connected to the first module and the radially external bearing element of the second bearing arrangement is connected to the second module.

The axially stationary component would normally be a clutch casing. The complete force connection within the clutch is then obtained.

To allow the supply of pressure fluid to be achieved easily, the first and the second modules are preferably held nonrotatably with respect to an inertial system in which the axially stationary component rotates. Furthermore, a valve arrangement can be connected substantially rigidly to the first or second module and by means of which fluid can be selectively provided. This valve arrangement can operate on a pressure balance principle, but can also comprise any other valve arrangement by means of which working fluid can be introduced into the fluid chamber or can be discharged from the fluid chamber in a controlled manner.

To save components, this valve arrangement can have a dual role in that both the first and second module are held substantially non-rotatably.

With the friction clutch known from DE 42 08 906 Al, the two modules of the telescopic unit are each tubular in design. In other words, an external module which forms a cylinder and is supported on the clutch casing surrounds the other tubular module which acts on the diaphragm spring. The external module carries a seal which acts in a sealing manner on an outer peripheral face of the internal module, and the internal module carries a seal, which acts in a sealing manner on an inner peripheral face of the external module. The result of this configuration is that, on the one hand, the fluid chamber which is also substantially tubular or annular in design is located relatively close to the axis of rotation so that, with a predetermined fluid actuating pressure, a correspondingly small disengagement force can only be achieved owing to the relatively low effective active face of the telescopic unit. On the other hand, this configuration means that the fluid chamber and the bearing arrangement by means of which the external module is supported on the casing, are axially staggered, and this leads to a relatively great total axial length.

To overcome these drawbacks, the present invention also provides a friction clutch comprising an energy store, which is operated by a pressure fluid actuating arrangement for carrying out clutch engagement or disengagement processes, wherein the pressure fluid actuating arrangement is a telescopic unit with a first module supported axially via a first bearing arrangement on a component which is axially substantially stationary, and a second module which is displaceable axially with respect to the first module via a second bearing arrangement for loading the energy store and a fluid chamber into which a working fluid can be introduced to produce the axial relative movement between the first and the second modules, wherein each of the first and second modules has a radially external wall region which surrounds a radially internal wall region to define a substantially annular space therewith, the radially internal wall region and the radially external wall region of each module are connected to one another by a respective connecting wall region, the radially external wall regions of the two modules are axially displaceable in a substantially fluid-tight manner with 6 respect to one another and the radially internal wall regions of the two modules are axially displaceable in a substantially fluid-tight manner with respect to one another.

With such a construction the two modules are not tubular in design as is known but each have annular portions which are substantially concentric to one another and are connected to one another. This affords the advantage that greater freedom of design of the effective active size of the fluid chamber can be achieved with the result that a much higher disengagement force can be achieved with the same fluid actuating pressure. Much greater freedom of design can also be achieved with respect to the relative positioning between the first bearing arrangement and the fluid chamber, as described hereinafter.

With a clutch of this design, for example, an inner peripheral face of the radially external wall region of one of the first and second modules and an outer peripheral face of the radially external wall region of the other of the first and second modules can oppose one another at least in certain regions and can be sealed in a fluid-tight manner with respect to one another. Similarly the inner peripheral face of the radially internal wall region of the one module and an outer peripheral face of the radially internal wall region of the other module can oppose one another at least in certain regions and can be sealed in a fluid-tight manner with respect to one another.

For obtaining an axially short overall shape, moreover, the connecting wall region of one module can be connected to the radially external wall region of the one module at an end region of the radially external wall region close to the axially stationary component and can be connected to the 7 radially internal wall region of the one module at an end region of the radially internal wall region remote from the axially stationary module. It is preferable if the one module is the first module and the connecting wall region of the first module extends approximately axially at least in certain regions between its connection to the radially external and the radially internal wall region of the first module. The first bearing arrangement is surrounded at least in certain regions by the radially internal wall region, a substantially radially extending region of the connecting wall region and the approximately axially extending region of the connecting wall region of the first module.

In an alternative embodiment, an inner peripheral face of the radially external wall region of one of first and second modules and an outer peripheral face of the radially external wall region of the other of the first and second modules can oppose one another at least in certain regions and can be sealed in a fluid-tight manner with respect to one another, and an outer peripheral face of the radially internal wall region of the one module and an inner peripheral face of the radially internal wall region of the other module can oppose one another at least in certain regions and can be sealed in a fluid-tight manner with respect to one another.

In this case, the one module is preferably the second module.

In a further aspect the invention provides a friction clutch comprising an energy store, which is operated by a pressure fluid actuating arrangement for carrying out clutch engagement or disengagement processesf wherein the pressure fluid actuating arrangement is a telescopic unit with a first module supported axially via a first bearing arrangement on a component which is axially substantially stationary, and a 8 second module which is displaceable axially with respect to the first module via a second bearing arrangement for loading the energy store and a fluid chamber into which a working fluid can be introduced to produce the axial relative movement between the first and the second modules, wherein the first bearing arrangement and the fluid chamber overlap axially at least in certain regions.

The invention may be understood more readily, and various other aspects and features of the invention may become apparent, from consideration of the following description.

Embodiments of the invention will now be described in more detail hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a longitudinal sectional view of part of a friction clutch constructed in accordance with the invention; Figure 2 is a longitudinal sectional view of another friction clutch constructed in accordance with the invention and Figure 3 is a schematic axial end view representing the friction clutch shown in Figure 2.

As shown in Figure 1, a motor vehicle friction clutch 10 employs a pressure plate unit or module 12 with a casing 14 and a pressure plate 16 which is held non-rotatably in the casing 14, for example via tangential leaf springs or the like but is displaceable with respect to the casing 14 in the direction of an axis of rotation A. An energy store in the form of a diaphragm spring 18 is supported in a radially external region on a support portion 20 in the casing 14 and urges the pressure plate 16 toward a flywheel 22 radially 9 within this support region 20. The pressure plate 12, via the casing 14, is rigidly connected to a flywheel 22, which can also be constructed, for example as a dual mass flywheel, in a manner known per se, in a radially external region. A clutch disc designated generally by 24 is clamped with its friction linings, in a manner known per se, between the pressure plate 16 and the flywheel 22, when the clutch is engaged, i.e. when the pressure plate 16 is in the state biased to the left in Figure 1.

The diaphragm spring 18 extends radially inwardly from the casing 14 and has, for example in its radially internal region, a plurality of spring tongues 26 on which a pressure fluid actuating arrangement 28 described in detail hereinafter acts for carrying out disengagement processes, i.e. for releasing the pressure plate 16 from the loading by the diaphragm spring 18.

The pressure fluid actuating arrangement 28 comprises a telescopic unit 30 which can be retracted axially by the supply of pressure fluid and comprises a first module 32 and a second module 34 which is displaceable with respect to the f irst module 32 in the direction of the axis of rotation A. The f irst module 32 is designed in the manner of an annular piston which is fitted into an annular cylinder which, in turn, is formed by the second module 34. The annular piston 32, in other words the first module 32, comprises a radially external wall region 52, a radially internal wall region 38 and a connecting wall region 40 which connects these two wall regions 52, 38 and is substantially annular in design. It is pointed that this approximately pot-shaped structure can be obtained from a single component, for example by a deep drawing process, but that, for example, the radially internal wall region 38 can similarly be formed by a separate component connected to the connecting wall region 40 by welding or the like, as shown in Figure 1.

The annular cylinder 34, in other words the second module 34, comprises a radially external wall region 42, a radially internal wall region 44 and a connecting wall region 46. An integral structure is also possible here again, but, for reasons of production, the radially internal wall region 44 is designed as a separate component which, in turn, is rigidly connected to the connecting wall region 46, for example by welding or caulking or the like, as will be described hereinafter.

The annular piston 32 carries respective sealing elements 48, 50 which are annular in design and provide: i) a seal between an outer peripheral face 36 of the radially external wall region 52 of the annular cylinder 32 and an inner peripheral face 54 of the radially external wall region 42 of the annular piston 34 and ii) a seal between an inner peripheral face 56 of the radially internal wall region 38 of the annular piston 32 and an outer peripheral face 58 of the radially internal wall region 44 of the annular cylinder 34. In this way, a fluid chamber 69 into which pressure fluid can be introduced through a valve arrangement designated generally by 62 for disengagement of the clutch is formed in the telescopic unit 30.

The annular piston 32 is supported on the casing 14 of the pressure plate module 12 of the clutch 10 via a first bearing arrangement 64. The first bearing arrangement 64 is composed of a radially external bearing ring 66 and a radially internal bearing ring 68 as well as a plurality of balls 70 as rolling bodies between these bearing rings 66, 68. The radially external bearing ring 16 acts on the annular piston 32 and can be, f or example, rigidly connected thereto or the connection can be produced easily by loading with axial pressure. The radially internal bearing ring 68 is fixed on the casing 14 by a fixing 72 or the like.

The annular cylinder 34 with its internal wall region 44 engages axially on the diaphragm spring 18 with a second bearing arrangement 74. This second bearing arrangement 74 is likewise composed of a radially external bearing ring 76, a radially internal bearing ring 80 with balls 84 as rolling bodies therebetween. The ring 76 is fixed by a fixing or the like 78 on a flange-like projection of the internal wall region 44 while the ring 80 is rigidly connected to a driving ring 82, for example by welding. The driving ring 82 is provided with a plurality of driving projections 86 which engage in each case between two peripherally adjacent spring tongues 26 and therefore produce a rotational coupling between the radially internal bearing ring 80 and the diaphragm spring 18. A biasing element, for example in the form of a spring washer 88 or the like is provided by means of which the diaphragm spring 18 is held axially rigidly on the radially internal bearing ring 80.

The two bearing arrangements 64, 74 are sealed by sealing elements so the balls 70 or 84 run in each case in a chamber which is preferably completely sealed and contains lubricant. As described in more detail hereinafter, the radially external bearing rings 66, 76 do not rotate with respect to the axis of rotation A but the radially internal bearing rings 68 or 80 rotate with the casing 14 or the diaphragm spring 18, so several advantages are obtained during operation. On the one hand, an excessive centrifugal effect is prevented from leading to an accumulation of lubricant from the bearing arrangements 64, 74 in the radially external region and 12 therefore to inadequate lubrication in the radially internal region. Owing to the lack of this tendency to shift radially outward, the lubricant pressure in the radially external region, which acts on the sealing element, is reduced so sealing problems can also be avoided. Sealing elements which act with sliding contact, for example on the radially internal bearing ring 68, 80, can be used. As substantially no lubricant pressure is built up here, there is no risk of a leakage of lubricant. Furthermore, the sliding rate occurring with the superimposed rolling and sliding movements of the bearing balls 70, 84 is diminished, with reduced stress and reduced wear of the individual bearing arrangements 64, 74.

It is pointed out that a biasing spring which biases the annular cylinder 34 which is axially movable in this embodiment away from the clutch casing 14 can act, for example, between the connecting wall region 40 and the connecting wall region 46. As a result, the annular piston 32 is pressed axially onto the clutch casing 14 and therefore the radially external bearing ring 66 of the first bearing arrangement 64 by the pulling support of the annular cylinder 34 on the diaphragm spring 18. A rigid connection between these two components is not then required, so self-centring of the entire pressure medium actuating arrangement 28 can be achieved owing to the possible relative radial movability.

With respect to the construction of the valve arrangement 62, it is pointed out that it can have any desired construction. For example, it is possible for the valve arrangement 62 to comprise an electrically controllable valve which is opened according to the detected actuation of a clutch pedal and therefore allows pressure fluid, for example air or oil, to enter the fluid chamber 69 or escape from this fluid chamber 69. Furthermore, as shown in the illustration, it is possible 13 1 for the valve arrangement 62 to operate on the so-called pressure balance principle of which the construction is known in the state of the art and is not described in detail here. Essentially only the following is pointed out with regard to the operating principle of a pressure balance. The pressure balance communicates via a pressure fluid supply line 90, for example an air supply line 90, with a pressure fluid source. The pressure balance also communicates via a control fluid line 92 with a control member, for example a master cylinder, which, in turn, is activated by a clutch pedal. This control fluid is generally a liquid, owing to the low compressibility. The pressure balance contains a valve element which can open or interrupt the pressure fluid flow path between the pressure fluid line 90 and the fluid chamber 69, and can therefore either keep the fluid chamber 69 sealed or open it to the environment. The valve element can be displaced by the fluid pressure of the control fluid.

If, for example, starting from the engaged state of the clutch 10 shown in Figure 1, the clutch pedal is actuated and the master cylinder therefore activated, the pressure of the control fluid is increased and the valve element therefore displaced in such a way that the pressure fluid, for example the compressed air, can flow via the pressure fluid line 90 into the fluid chamber 69. Owing to this entering fluid and the pressure thus built up in the fluid chamber 69, the annular cylinder 34 is moved to the right in Figure 1, i.e. away from the casing 14, with the result that the spring tongues 26 of the diaphragm spring 18 are pulled and the force loading the pressing plate 16 is gradually removed. During this displacement of the annular cylinder 34, which axially entrains the valve arrangement 62, i.e. the pressure balance, fixed thereon, the volume of a measuring cylinder chamber 94 in which a measuring piston 96 is guided in a sealed manner is 14 similarly increased. This measuring piston 96 is in turn rigidly connected to the annular cylinder 32. The measuring cylinder chamber 94 communicates with the control fluid line 92, so, as the volume of the measuring cylinder chamber 94 increases, fluid flows from the control fluid line 92 into the measuring cylinder chamber 94 with the result that the fluid pressure in the control fluid line 92 decreases. Owing to this reduction in pressure in the control fluid line 92, the force loading of the valve element is also reduced so it is displaced and therefore interrupts the fluid connection between the pressure fluid line 90 and the fluid chamber 69 and keeps the fluid chamber 69 sealed. A state of equilibrium which ultimately depends on the extent of actuation of the clutch pedal is therefore achieved owing to the gradual ingress of control fluid from the control fluid line 92 into the measuring cylinder chamber 94. Starting from the disengaged state then existing, the fluid pressure in the control fluid line 92 is further reduced during release of the clutch pedal so the valve element of the pressure balance is displaced further and the fluid chamber 69 opens to the environment while the fluid connection between the pressure fluid line 90 and the fluid chamber 69 is still interrupted, so pressure fluid, generally compressed air, can escape to the environment or into a fluid reservoir. Owing to the biasing force of the diaphragm spring 18, the annular cylinder 34 is then pulled axially toward the casing 14 via the bearing arrangement 74, the measuring piston 96 also entering the measuring cylinder chamber 96 again. The state shown in Figure 1 is then ultimately reached again.

Although the operating principle of a pressure balance has been described hereinbefore, it is again pointed out that actuation by an integrated pneumatic master cylinder or the like can also be provided.

To obtain a simple fluid connection between the pressure fluid line 90 and the fluid chamber 60, the entire telescopic unit 30 with the valve arrangement 62 held thereon is non-rotatable with respect to a stationary reference system which can be defined, for example, by a motor vehicle, and only the components consisting of clutch casing 14 and diaphragm spring 18 as well as the bearing rings 68, 80 fixed thereon, cooperating with the telescopic unit 30 ultimately rotate. This can be achieved, for example, in that the valve arrangement 62 penetrates radially outward through an orifice 98 in a gear bell designated generally by 100. It is also possible to provide the annular cylinder 34 with a first toothed arrangement 102 which meshes with a second toothed arrangement 104, but is axially displaceable with respect thereto. The second toothed arrangement 104 can again be fixed on a stationary, i.e. non-rotating component, for example a gearbox 106 or the like. In the arrangement illustrated, the non-rotatable positioning of the annular piston 32 is obtained, for example, by the measuring piston 96 which engages in the measuring cylinder chamber 94.

Owing to the design of the telescopic unit 30 with its two modules 32, 34 acting as an annular piston and cylinder, very reliable operation is achieved in which the occurrence of tilting or the like is almost avoided as guide portions which keep the two modules 32, 34 in a suitable position with respect to one another are formed in each case by the mutually opposed surface regions.

The following procedure, for example, can be adopted when assembling the clutch 10. The diaphragm spring 18 is first combined with an assembly comprising a bearing arrangement 74 and the internal wall region 44 of the second module 34. For 16 this purpose, the bearing arrangement 74 can initially be inserted into the diaphragm spring 18 with the spring 88 already provided thereon, and the driving ring 82 can then be applied and welded to it or connected by a ciamping ring or the like. Thereafter or therebefore, the internal wall region 44 is rigidly connected to the external bearing ring 76 by the fixing ring 78 or the like. As a further preparatory measure, the bearing arrangement 64 is introduced into the central orifice of the casing 14 and the radially internal bearing ring 68 is then fixed on the casing 14 by means of the fixing ring or in a different way. Once this has been done, the diaphragm spring 18 in the illustration in Figure 1 is moved from the left with the internal wall region 44 of the second module 34 axially through the first bearing arrangement 64. The first module 32 with its radially internal wall region 38 and the seal 48 can then be pushed onto the internal wall region 44 of the second module 34, whereupon the remainder of the second module 34, i.e. the external wall region 42 can be pushed on axially with the connecting wall region 46 provided integrally thereon and the connecting wall region 46 can be connected to the internal wall region 44. However,the first module 42 and the remainder of the second module 34 can also be inserted into one another beforehand and can then be pushed onto the internal wall region 44 as an assembled unit.

A simple assembly process is thus possible. Furthermore, the design according to the invention allows easy disassembly of the valve arrangement 62 through the gear bell 100, without having to dismantle the entire gear mechanism.

Figure 2 shows an alternative embodiment of a friction clutch in accordance with the invention. Components corresponding to previously described components with respect to construction or function are designated by the same reference numerals with 17 addition of an appendix "a". The constructional differences which exist with respect to the embodiment according to Figure I will essentially be described hereinafter.

The embodiment shown in Figure 2 differs with respect to the embodiment shown in Figure 1 substantially by the constructional and therefore also functional design of the two modules 32a, 34a. In contrast to the design according to Figure 1, the first module 32a is accordingly designed in such a way that its external wall region 52a, with an inner peripheral face 108a thereof sealed by the sealing element 50a, opposes an outer peripheral face 110a of the external wall region 42a of the second module 34a. Radially internally to radially externally, the respective annular wall regions surrounding the axis of rotation A substantially concentrically are staggered, beginning with the internal wall region 44a of the second module 34a adjoined by the internal wall region 38a of the first module 32a. This is followed by the external wall region 42a of the second module 34a, and the configuration is completed by the external wall region 52a of the first module 32a. With an embodiment of this type, it is no longer possible to describe one of the modules 32a, 34a functionally as a cylinder or as a piston in the sense of the embodiment according to Figure 1. owing to the radial staggering in the various wall regions, each of the modules 32a, 34a basically or functionally has substantially the same configuration and therefore the same function.

According to a further constructional difference, the connecting wall region 40a of the first module 42a, in a radially external region, is connected to the radially external wall region 52a of the first module 32a in an end region thereof close to the casing 14a, whereas the attachment of the connecting wall region 40a to the internal wall region 18 38a takes place in an end region thereof remote from the casing 14a. A configuration of the connecting wall region 40a is therefore obtained in which the connecting wall region 40a has a substantially axially extending portion 112a and one or more substantially radially extending portions 114a. In particular, the first bearing arrangement 64a rests on the radially extending portion 114a adjoining the internal wall region 38a, so the first bearing arrangement 64a is almost completely encapsulated by the substantially axially extending portion 112a, the substantially radially extending portion 114a and the internal wall region 38a and is therefore protected very well from impurities. Despite the encapsulation of this first bearing arrangement 64a, adequate cooling of this bearing is nevertheless ensured by the working fluid flowing through the fluid chamber 60a. It can also be seen that, owing to this configuration, the fluid chamber here designated 60a completely overlaps the first bearing arrangement 64a in the axial direction so the overall axial length can be shortened in the region of the pressure fluid actuating arrangement 28. A cylindrical portion 116a of the casing 14a adjoins the radially internal bearing ring 68a of the first bearing arrangement 64a or is connected to it in order to rotate. A configuration is therefore obtained in which the telescopic unit 30a, i.e. the first module 32a thereof, is no longer supported on the casing 14a in its front end region facing the casing 14a, but is ultimately supported on the casing 14a in a back region further removed from the casing 14a. A further constructional difference from the embodiment according to Figure 1 is that the valve arrangement 62a is now fixed on the module which is axially fixed during the performance of disengagement processes, i.e. is rigidly connected to the module 32a. This simplifies the provision of fluid lines and also allows the orifice 98a in the gear bell 100a to be shorter axially in design. An advantage is that the 19 ingress of impurities or foreign bodies into the interior of the gear bell 100a can be prevented. For this purpose, as shown, for example, in Figure 3, an elastic closure element 120a can be provided in the orifice 98a to surround the valve arrangement 62a. The element 120a allows slight peripheral and axial movements of the valve arrangement 62a but otherwise allows almost tight closure of the gear bell 100a. During the occurrence of tumbling movements of the clutch casing 14a, therefore, there is no squeezing in the region of the orifice 98a nor striking noises of the valve arrangement 62a at the peripheral edge of the orifice 98a.

Also with the embodiment according to Figure 2, the internal bearing rings 68a or 80a are connected in each case to the rotating components, i. e. the casing 14a and the diaphragm spring 18a, whereas the radially external bearing rings 66a and 76a interact with the first module 32a or the second module 34a. The above-described advantages are thus also present.

It is pointed out that, as shown, f or example, in Figure 2, the bearing arrangements with their respective bearing rings do not have to act directly on the associated modules, but intermediate elements such as, for example, a connecting ring 122a, can be provided with which the radially external bearing ring 76a of the second bearing arrangement 74a is attached to the associated module.

The embodiment according to Figure 2 also shows the biasing spring 124a, which produces a basic bias in the pressure fluid actuating arrangement 21a and therefore, in particular, ensures that the first module 32a makes pressure contact with the casing 14a via the first bearing arrangement 64a. owing to the special design or shaping of the fluid chamber 60a, which has a radially external annular region here, this biasing spring 124a is simultaneously guided.

Figure 2 also shows that, with the pressure fluid actuating arrangement 28a, at least one compensating spring 126a is provided which acts between the first module 32a and the second module 34a and compensates for any tilting moment possibly transmitted to the second module 34a by the measuring piston 96a. As the measuring piston 96a acts eccentrically on the module 34a, there is otherwise a danger that the second module 34a will be tilted or biased in a tilting direction with respect to the first module 32a owing to the pressure of the control fluid which has built up in the measuring cylinder chamber measuring chamber 94a. This will be prevented by the compensating spring 126a.

In both embodiments described hereinbefore, in which an annular chamber is enclosed in each case by the respective wall regions of the two modules and a correspondingly annular fluid chamber is created by assembling the two modules, the advantage arises that the effectively used surface region of the fluid chamber can be increased, i.e. the active radius of the fluid chamber can easily be increased with the result that an elevated disengagement force can be provided with equal pressure fluid pressure.

The present invention provides a friction clutch with which a complete force connection is provided within the clutch itself on actuation of the clutch. In other words, the disengagement force does not have to be absorbed by external bearings. A clutch of this type can be used in many types of vehicle without significant modifications. It is also obvious that, although pulled-to- release clutches have been shown in each case hereinbefore, use in a pressed-to-release clutch is also 21 easily possible, in which the axially displaceable module is moved toward the pressure plate in each case.

It is pointed out that the term "friction clutch" as used in the present application and, in particular, in the claims, refers to the module on which the features essential to the invention are embodied. In other words, the module described as "friction clutch" does not necessarily comprise, for example, a flywheel or a clutch disc, as both clutch disc and flywheel are of secondary importance with respect to the important aspects of the present invention. A person skilled in the art can see that the friction clutch defined, in particular, in the claims can generally be obtained by combining a unit which can basically be described as a pressure plate module with a pressure fluid actuating arrangement forming the disengagement mechanism.

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Claims (15)

Claims

1. A friction clutch comprising an energy store (18; 18a) which is operated by a pressure fluid actuating arrangement (28; 28a) for carrying out clutch engagement or disengagement processes, wherein the pressure fluid actuating arrangement (28; 28a) is a telescopic unit (30; 30a) with a first module (32; 32a) supported axially via a first bearing arrangement (64; 64a) on a component (14; 14a) which is axially substantially stationary, and a second module (34; 34a) which is displaceable axially with respect to the first module (32; 32a) via a second bearing arrangement (74; 74a) for loading the energy store (18; 18a) and a fluid chamber (60; 60a) into which a working fluid can be introduced to produce the axial relative movement between the first and the second modules (32, 34; 32a, 34a), wherein at least one of the bearing arrangements (64, 74; 64a, 74a) comprises a radially external bearing element (66, 76; 66a, 76a), a radially internal bearing element (68, 80; 68a, 80a) and a plurality of bearing bodies (70, 84; 70a, 84a) therebetween and the radially external bearing element (66, 76; 66a, 76a) of the at least one bearing arrangement (64, 74; 64a, 74a) is connected to one of the first and second modules (32, 43; 32a, 34a) which is associated with the at least one bearing arrangement.

2. A friction clutch according to claim 1, wherein both bearing arrangements (64, 74, 64a, 74a) each comprise radially internal and external bearing elements with bearing bodies therebetween, the radially external bearing element (66; 66a) of the first bearing arrangement (64; 64a) is connected to the first module (32; 32a) and the radially external bearing element (76; 76a) of the second bearing arrangement (74; 74a) is connected to the second module (34; 34a).

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3. A friction clutch according to claim 1 or 2, wherein the axially stationary component (14; 14a) is a clutch casing (14; 14a).

4. A friction clutch according to any one of claims 1 to 3, wherein the first and the second modules (32, 34; 32a, 34a) are held non-rotatably with respect to an inertial system in which the axially stationary component (14; 14a) rotates.

5. A friction clutch according to any one of claims 1 to 4, and further comprising a valve arrangement (62; 62a) which is connected substantially rigidly to the first or second module (32, 34; 32a, 34a) and by means of which fluid can be introduced selectively to the fluid chamber (60; 60a).

6. A friction clutch according to claim 5, wherein the valve arrangement (62; 62a) operates on a pressure balance (62; 62a) principle.

7. A friction clutch according to claim 6, wherein the first and the second module (32, 34; 32a, 34a) are held substantially non-rotatably by means of the valve arrangement (62; 62a).

8. A friction clutch comprising an energy store (18; 18a), which is operated by a pressure fluid actuating arrangement (28; 28a) for carrying out clutch engagement or disengagement processes, wherein the pressure fluid actuating arrangement (28; 28a) is a telescopic unit (30; 30a) with a first module (32; 32a) supported axially via a first bearing arrangement (64; 64a) on a component (14; 14a) which is axially substantially stationary, and a second module (34; 34a) which is displaceable axially with respect to the first module (32; 32a) via a second bearing arrangement (74; 74a) for loading 24 the energy store (18; 18a) and a fluid chamber (60; 60a) into which a working fluid can be introduced to produce the axial relative movement between the first and the second modules (32, 34; 32a, 34a), wherein each of the first and second modules (32, 34; 32a; 34a) has a radially external wall region (52, 42; 52a, 42a) which surrounds a radially internal wall region (38, 44; 38a, 44a) to define a substantially annular space therewith, the radially internal wall region (38, 44; 38a, 44a) and the radially external wall region (52, 42; 52a, 42a) of each module (32, 34; 32a, 34a) are connected to one another by a respective connecting wall region (40, 46; 40a, 46a), the radially external wall regions (52, 42; 52a, 42a) of the two modules (32, 34; 32a, 34a) are axially displaceable in a substantially fluid-tight manner with respect to one another and the radially internal wall regions (38, 44; 38a, 44a) of the two modules (32, 34; 32a, 34a) are axially displaceable in a substantially fluid-tight manner with respect to one another.

9. A friction clutch according to claim 8, wherein an inner peripheral face (108a) of the radially external wall region (52a) of one of the first and second modules (32a, 34a) and an outer peripheral face (110a) of the radially external wall region (42a) of the other of the first and second modules (32a, 34a) oppose one another at least in certain regions and are sealed in a fluid-tight manner with respect to one another, and in that the inner peripheral face (56a) of the radially internal wall region (38a) of the one module (32a) and an outer peripheral face (58a) of the radially internal wall region (44a) of the other module (34a) oppose one another at least in certain regions and are sealed in a fluid- tight manner with respect to one another.

10. A friction clutch according to claim 9, wherein the connecting wall region (40a) of the one module (32a) is connected to the radially external wall region (52a) of the one module (32a) at an end region of the radially external wall region (52a) close to the axially stationary component (14a) and is connected to the radially internal wall region (38a) of the one module (32a) at an end region of the radially internal wall region (38a) remote from the axially stationary module (14a).

11. A friction clutch according to claim 10, wherein the one module (32a) is the first module (32a) the connecting wall region (40a) of the one module (32a) extends approximately axially at least in certain regions between its connection to the radially external and the radially internal wall region (52a, 38a) of the one module (32a), and the first bearing arrangement (64a) is surrounded at least in certain regions by the radially internal wall region (38a), a substantially radially extending region (114a) of the connecting wall region (40a) and the approximately axially extending region (112a) of the connecting wall region (40a) of the first module (32a).

12. A friction clutch according to claim 8, wherein an inner peripheral face (54) of the radially external wall region (42) of one of the first and second module (32, 34) and an outer peripheral face (36) of the radially external wall region (52) of the other of the first and second modules (32, 34) oppose one another at least in certain regions and are sealed in a fluid-tight manner with respect to one another, and an outer peripheral face (58) of the radially internal wall region (44) of the one module (34) and an inner peripheral face (56) of the radially internal wall region (38) of the other module (34) oppose one another at least in certain regions and are sealed in a fluid-tight manner with respect to one another.

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13. A friction clutch according to claim 12, wherein the one module (34) is the second module (34).

14. A friction clutch comprising an energy store (18; 18a), which is operated by a pressure fluid actuating arrangement (28; 28a) for carrying out clutch engagement or disengagement processes, wherein the pressure fluid actuating arrangement (28; 28a) is a telescopic unit (30; 30a) with a first module (32; 32a) supported axially via a first bearing arrangement (64; 64a) on a component (14; 14a) which is axially substantially stationary, and a second module (34; 34a) which is displaceable axially with respect to the first module (32; 32a) via a second bearing arrangement (74; 74a) for loading the energy store (18; 18a) and a fluid chamber (60; 60a) into which a working fluid can be introduced to produce the axial relative movement between the first and the second modules (32, 34; 32a, 34a), wherein the first bearing arrangement (64a) and the fluid chamber (60a) overlap axially at least in certain regions.

15. A friction clutch or modular arrangements therefor substantially as described with reference to, and as illustrated in Figure 1 or Figures 2 and 3 of the accompanying drawings.