WO2005093275A1

WO2005093275A1 - Variable release force clutch device

Info

Publication number: WO2005093275A1
Application number: PCT/FR2005/050160
Authority: WO
Inventors: Xavier Fesselet; Michel Bacher; Olivier Hudon; Matthieu Malley
Original assignee: Valeo Embrayages
Priority date: 2004-03-12
Filing date: 2005-03-14
Publication date: 2005-10-06
Also published as: FR2867535B1; FR2867535A1

Abstract

The inventive friction clutch device (1) comprises at least one diaphragm (20) provided with a radially external annular part (23) which forms a « Belleville » type disc and projected fingers (25) radially extending from said annular part to a clutch axis of rotation (4), at least one clutch release bearing (10) comprising an end (11) resting against the free end of the fingers during the disengaging movement of said clutch releasing bearing. At least one end of the clutch release bearing and the free end of the fingers is provided with at least two bearing surfaces (21, 22) which are separated from each other and can be brought into contact with the end of the clutch release bearing and the free end of fingers during the disengaging movement of said clutch releasing bearing.

Description

Clutch device with variable thrust force

The invention relates to a friction clutch device, in particular intended for a motor vehicle.

In document FR2745870 A1, there is described a clutch device comprising, linked to one another in rotation about an axis of rotation, a support plate, a cover and a pressure plate. The latter is, moreover, able to move in translation along the axis of rotation relative to the support plate and the cover. In addition, the clutch device described comprises a diaphragm bearing on the cover, on the one hand, and on the pressure plate, on the other hand, while being elastically deformable between disengaged and engaged positions so as to move the _. pressure plate along the axis of rotation of the clutch device towards the support plate in order to tighten friction and to put the clutch device in a engaged state. The diaphragm comprises an external peripheral part forming a washer called "Belleville" coming to bear, on the one hand, on the pressure plate and, on the other hand, on the cover, as well as several fingers extending radially towards the axis of rotation from the "Belleville" washer and each having, at an internal periphery, a free end.

At rest, the clutch device is in a engaged state, the friction being clamped between the support and pressure plates under the action of the diaphragm.

To bring the aforementioned clutch device into a disengaged state, disengaging means press on the free ends of the diaphragm fingers in a disengaging movement in order to elastically deform the diaphragm between the engaged position and the disengaged position. In order to prevent excessive disengaging movement or disengaging overtravel, the aforementioned document describes the use of a ring made of material from several arms, themselves made from material of the cover, thus connecting the ring to the cover. This ring is placed in the path followed by the free ends of the fingers during the disengaging movement. Thus, at a predetermined moment of the disengagement movement, the free ends of the fingers come to bear on the ring, preventing any additional disengagement movement.

The disadvantage of such a clutch device is that the cover has a complex shape and, therefore, is more difficult and more expensive to produce. In addition, the assembly of the diaphragm with the cover is also more complex.

Another possibility is to provide the stop in the actuator, if the latter is of the hydraulic or pneumatic type. One such example is in the document FR2780468 presenting a piston end-of-travel stop at the end of the guide tube of the actuator. This device has the drawback of making it difficult and expensive to adapt the stop to a particular case. In addition, withstand heavy loads that can be applied regularly is not guaranteed. Finally, it is necessary to provide in this case an overtravel of the order of 8mm of the piston and therefore to provide a clearance of the diaphragm accordingly and have, therefore, an increased size.

An object of the invention is to provide a clutch device making it possible to solve the aforementioned problems.

To this end, provision is made, according to the invention, for a friction clutch device comprising at least one diaphragm comprising a radially external annular part forming a Belleville-type washer and fingers extending radially projecting from the annular part towards an axis of rotation of the clutch, at least one clutch release bearing having one end capable of coming to bear on a free end of the fingers during a clutch release movement of the clutch release bearing, at least one of the end of the clutch release bearing and the free end of fingers comprising at least two bearing surfaces separated from each other and capable of coming successively into contact with each other at the end of the clutch release bearing and the free end of the fingers, during the clutch release movement of the stop.

Advantageously but optionally, the clutch device has at least one of the following characteristics: - The device comprises at least two friction discs, - The device comprises a second diaphragm capable of cooperating with one of the two friction discs, the first diaphragm being able to cooperate with the other of the two friction discs, - ^• - The device comprises at least one wear take-up system, - The device is of the pushed type. - The device is of the pulled type. - The clutch release bearing comprises a plate of substantially annular shape comprising the end capable of coming onto the free end of the fingers during the clutch release movement. - The plate of substantially annular shape is mounted on the free end of the fingers of the diaphragm by fixing means. - The fixing means are clipping means. - The plate of substantially annular shape has on a internal periphery a substantially vertical wall capable of partially enveloping the free end of the fingers of the diaphragm. - The two bearing surfaces are arranged so that, during the disengagement movement, a change of contact from one to the other of the bearing surfaces takes place substantially at the end of the disengagement movement, the stop clutch then entering a disengaging overtravel state. Other characteristics and advantages of the invention will appear during the description below of a preferred embodiment as well as variants. In the accompanying drawings: - Figure 1 is a block diagram of the invention; - Figure 2 is a graph illustrating the operation of the diagram of Figure 1; - Figures 3 and 4 are variants of the block diagram of Figure 1 according to the invention; - Figure 5 is a partial sectional view of a first embodiment according to the invention; and, - Figure 6 is a partial sectional view of a second embodiment according to the invention.

With reference to FIG. 1, we will first describe the principle of embodiment of the invention.

A clutch device according to the invention 1 schematically comprises at least one support plate 9, at least one cover 6, at least one pressure plate 8, at least one clutch means 20 (here, in the form of 'a diaphragm 20), as well as at least one friction 7. The various aforementioned components are assembled together in a substantially coaxial manner with respect to each other along an axis 4. Thus, the clutch device 1 can perform a movement of rotation about this axis 4. In general, the support plate is mounted at least in rotation on a driving shaft 5. The latter can come, for example, from a combustion engine like the end of a crankshaft . The support plate is also mounted, at least in rotation, with the cover 6. The pressure plate 8 is, in turn, mounted in rotation with the cover 6 and / or the support plate 9. In addition, the pressure plate 8 is capable of carrying out a translational movement along the axis 4 relative to the cover 6 and to the support plate 9. Return means 20, positioned here between the cover 6 and the plate pressure 8, allow to move the latter according to the aforementioned translational movement away from the support plate 9, and this, under certain conditions, in order to put the clutch device 1 in a disengaged state. The diaphragm 20 is generally rotatably mounted on the cover 6. It is able to deform elastically during the application of a force generated by declutching means 10. During this elastic deformation, the diaphragm 20 is able to perform a tilting movement at a connection 2 with the cover 6. In addition, the diaphragm 20 is capable of coming to bear 24 on the pressure plate 8. The diaphragm has two parts 23 and 25. The first part 23 is located between the connection 2 described above and the support 24. It has a general shape of a ring whose internal and external diameters are located substantially perpendicular to the connection 2 and the support 24. It is this part which mainly behaves like a "Belleville" washer during deformation of the diaphragm. The second part 25 has a series of several fingers formed integrally with the first part 23 and which extend from the internal diameter of this first part towards the axis 4 of the diaphragm 20, axis in the vicinity of which the fingers have a free end . In the clutch device 1 according to the invention, the fingers have at their free end a first surface 22 capable of coming to cooperate with the declutching means 10. In addition, the fingers have at a distance D from the first surface 22 in the direction of the part 23 of the diaphragm 20 a second surface 21, it is also able to come into contact with the declutching means 10. In a rest position, the diaphragm 20 has a position as illustrated in FIG. 1, to the left of the axis of rotation 4. In this rest position, the diaphragm 20 presses on the pressure plate so as to bring the latter closer to the support plate 9 according to the translational movement described above. The support force exerted by the diaphragm is greater than the return force exerted by the return means 40. When the diaphragm 20 is in the rest position, the clutch device 1 is in a engaged state. The friction 7, in turn, is mounted so as to be sandwiched between the pressure plates 8 and support 9. This friction 7 is adapted to rotate a driven shaft 3, such as, for example, a shaft d gearbox entry. When the clutch device 1 according to the invention is in a engaged state, the friction 7 is tightened by the pressure plate 8 on the support plate 9: it is then possible to transmit a torque of the driving shaft 5 to the driven shaft 3 through the clutch device 1.

The transition from a engaged state to a disengaged state is effected using the declutching means 10 mentioned above and capable of acting on the diaphragm 20 in order to deform it elastically to achieve this passage. For this, the declutching means comprise a stop having an end comprising at least one surface 11 capable of coming into contact with the fingers of the part 25 of the diaphragm 20.

We will now describe the operation of the clutch device 1 according to the invention, with reference to Figures 1 and 2. During a declutching movement, the declutching means 10 (or stop) perform a translational movement according to the axis 4 in order to pass the diaphragm 20 from its rest position (illustrated to the left of axis 4 in FIG. 4) to its deformed position (illustrated to the right of axis 4 in FIG. 1). At a predetermined moment of the declutching movement, the bearing force applied by the diaphragm 20 on the pressure plate has a value less than the value of the restoring force exerted by the return means 40 on this same plate. pressure: the latter then rises, releasing friction 7. No torque is then transmitted by the clutch device 1. In FIG. 2 is illustrated the evolution of the force at the level of the contact between the surface 11 of the stop 10 and the diaphragm fingers 20 during the declutching movement described above. A first curve 32 corresponds to a support of the stop 10 on the surface 22 of the fingers of the diaphragm, if this support was maintained all along the declutching movement. Under the same conditions, a second curve 31 corresponds to a similar support of the stop on the surface 21 of the fingers of the diaphragm. A third curve 30 corresponds to the evolution of the force transmitted to the diaphragm by the stop in a clutch device according to the invention and which we will now describe.

At the start of the declutching movement, the surface 11 of the stop 10 is in abutment on the surface 22. The force allowing the tilting by deformation of the diaphragm 20 at the connection 2 with the cover 6 applies to a distance D2 of said link (lever arm). With this support, the first part of the declutching movement has an evolution 30 of the force at the stop as a function of the displacement of the latter which follows the first curve 32. At a predetermined moment T of the declutching movement, the surface 11 of the stop 10 comes to bear with the second surface 21. Consequently, the distance between the support and the link 2 changes to a distance D1, less than the distance D2. The declutching movement then presents an evolution of the force at the stop as a function of the displacement of the latter which follows the second curve 31. Over the whole of the declutching movement of the clutch device according to the invention, the evolution of the force at the stop as a function of the displacement of the latter has a substantially staircase curve 30. A curve 30 'follows a general shape as shown in dotted line slightly offset from the aforementioned curve 30 due to a low elasticity of the components, in particular of the diaphragm fingers between the surfaces 21 and 22.

One practical application, among others, of such an operating principle as described above is to locate the moment T of the declutching movement in the vicinity of an end of a useful operating zone, that is to say say in the vicinity of the end of the declutching stroke, and to choose the distance • Dl (that is to say the position of the second surface 21) so that the effort of the bearing of the corresponding curve 30 at the start of the area of this curve 30 which substantially merges with the second curve 31 is greater than the maximum force that can be applied by the declutching means 10. Thus the structure plays the role of a limit stop in a simple and economical manner. It is possible to advantageously define the shape of the fingers (20) to adapt them to different stops (applied force, stroke, etc.).

We will now, with reference to FIGS. 3 and 4, describe two variants of the concept that we have just studied. The variant illustrated in FIG. 3 differs from the concept of FIG. 1 by the fact that, in the clutch device 101, the stop 110, forming part of the declutching means, comprises first 112 and second 111 surfaces separated by a distance From each other. These first 112 and second 111 surfaces have the same role as the first 22 and second 21 surfaces of the diaphragm 20 of FIG. 1 and previously described. The first 112 and second 111 surfaces are able to cooperate with the diaphragm 120. As before, during the operation of the clutch device 101, the first surface 112 presses on the diaphragm at the start of the disengagement movement. Then, the second surface 111 comes to bear at a determined moment on the diaphragm at a shorter distance from the tipping point of the diaphragm than for the first surface 112. A behavior curve thus obtained is similar to the aforementioned curve 30.

The second variant illustrated in FIG. 4 is a mixture of the concept of FIG. 1 and the variant of FIG. 3. The clutch device 401 of this second variant comprises a stop 110 similar to that of the variant of FIG. 3, as well as a diaphragm 20 similar to that of the concept of FIG. 1. In this second variant, the first 112 and second 111 surfaces of the stop 110 are capable of coming to bear, during a disengaging movement, with the first 22 and second 21 surfaces respectively and successively during said movement of declutching. The operation of this variant and the behavior curve are similar to those described above.

Referring to Figures 5 and 6, we will now describe two embodiments of a clutch device according to the invention, based on the concepts described so far.

The first embodiment of a clutch device 201, illustrated in FIG. 6, comprises: - a support plate 209 linked in rotation at least to a driving shaft which is not, here, shown, - a cover 206 mounted at least in rotation on the support plate 209, - a pressure plate 208 mounted in rotation with the cover and able to move relative to the cover in a translation parallel to the axis 4 of rotation of the device clutch 201. The connection between the pressure plate and the cover is made by return means not shown, - a diaphragm 220 rotatably mounted on the cover 206 using connection means 250 uniformly distributed over a circumference of the cover and diaphragm. The diaphragm 220 includes a part 223 forming a so-called "Belleville" washer coming to bear 224 with the pressure plate 208, on the one hand, and, on the other hand, bearing 202 with the cover 206. During an elastic deformation of the diaphragm 220 (deformation similar to that previously described for the diaphragm 20, 120 as to its principle and its effects on the pressure plate), the latter rocks at the level of the support 202, in order to allow the plate to move in translation pressure 208. In addition, the diaphragm comprises a second part 225 comprising a series of fingers uniformly distributed on a circumference, which extend radially towards the axis 4 from the part 223 forming a so-called "Belleville" washer and integral with it. - A friction 207 mounted at least in rotation on a shaft. driven 203 and able to be tightened, in order to transmit torque to this shaft, by the pressure plate on the support plate when the diaphragm 220 is in the so-called rest position - declutching means 210 comprising a concentric actuator mounted coaxially on the driven shaft 203. The actuator can be of the hydraulic and / or pneumatic type. This actuator comprises a jack comprising a piston 216 capable of carrying out a translation along the axis 4 in order to produce a disengaging movement. The piston 216 is able to cooperate with a stop 215, itself capable of coming to bear on the diaphragm 220. The stop 215 is here in the form of an annular sheet having a surface 211 of generally concave shape and positioned at within the device opposite the fingers 225 of the diaphragm 220 so as to come into abutment therewith. In the rest position of the diaphragm 220 (corresponding to the engaged state of the engaged device 201), illustrated to the left of the axis 4 in FIG. 5, the surface 211 is in abutment on a first surface 222 situated in the vicinity of a free end of the diaphragm fingers 220 at a distance D2 from the support 202. During the declutching movement, at a predetermined moment T, the surface 211 comes to bear with a second surface 221 of the diaphragm fingers located at a distance Dl of the support 202, distance Dl which is less than the distance D2. This change of support makes it possible to obtain a behavior curve at the level of the stop similar to the curve 30 described above.

In the embodiment of FIG. 5, the stop 215 is fixed to the diaphragm fingers by means of fixing means 252. These fixing means 252 can for example be a system of clips capable of being caught between two fingers of diaphragm. The fixing means 252 can be made by molding a thermoplastic material. In an alternative embodiment, the stop 215 can be mounted directly on the end of the piston 216 of the concentric actuator. In alternative embodiments, the declutching means 210 may be a fork system actuated either by a hydraulic and / or pneumatic actuator, an electric actuator, or a wheelhouse connecting the fork to a clutch pedal.

On the other hand, the clutch device 201 comprises means 260 for catching up on the wear of the friction 207. In the case illustrated in FIG. 5, the wear take-up means 260 "increase" the thickness of the plate pressure 208 in proportion to the wear of the friction linings 7, in particular by moving the pressure plate 208 away from the fulcrum 224 towards the friction 207. Such wear take-up means 260 are known per se. For more information, see FR 2 753 503 Al and FR 2 809 147 Al, for example. In an alternative embodiment, the wear take-up means can act by "increasing" the thickness of the cover 206, in particular by moving the support 202 of the diaphragm towards the friction 207. In all cases, the wear take-up means have the role of allowing the diaphragm to deform during the lifetime of the clutch device substantially between the same rest positions (clutched state of the clutch device) and deformed. (disengaged state of the clutch device as illustrated in Figure 5 to the right of axis 4).

We will now describe, with reference to FIG. 6, a second embodiment of a clutch device according to the invention. This embodiment differs from the previous embodiment in terms of the stop / diaphragm arrangement. The stop 315 has a substantially flat surface 311 and positioned opposite a diaphragm 320. The stop 311 is actuated by means of declutching 310 which are similar to the declutching means 210 previously described. At the start of the declutching movement (illustrated to the left of the axis 4 in FIG. 6), the surface 311 is supported on a first surface 322 situated in the vicinity of a free end of the fingers of the diaphragm 320. At a predetermined moment of the disengagement movement, the surface 311 comes into abutment with a • second surface 321 of the fingers of the diaphragm 320 distant radially outwardly from the first surface 322. The two surfaces 321 and 322 are positioned on the diaphragm 320 with respect to a support of the latter ci on a cover (both not shown) of the clutch device 301 similarly to the surfaces 221 and 222 of the first embodiment. As before, the stop 315 is mounted on the fingers of the diaphragm 320 using the fixing means 352,353. The fixing means comprise a fine washer called "Belleville" 352 mounted substantially parallel to the surface 311 and at a distance therefrom by bearing on a flange 353 of the stop 315. Here, the flange is formed by a ring 353 wedged in a groove arranged in the stop 315. The so-called "Belleville" washer 352 also bears on the fingers of the diaphragm 320 with sufficient force to hold the stop 315 in place on the end of the fingers of the diaphragm 320.

Although the concept and the previous embodiments have been described in the context of a “pushed” type clutch device, the invention can be used on: - a “pulled” type clutch device - a clutch device comprising several frictions - a device comprising several clutches (either on one or more of the clutches present) On the other hand, the clutch device according to the invention can have a stop controlled by a computer thus managing the clutch operation. Of course, many modifications can be made to the invention without going beyond the ambit of the latter.

Claims

REVENDICA IONS

1. Friction clutch device (1; 101; 201; 301; 401) comprising at least one diaphragm (20; 120; 220; 320) comprising a radially external annular part (23; 223) forming a washer of type " Belleville "and the fingers (25; 225) extending radially projecting from the annular part towards an axis of rotation (4) of the clutch, at least one declutching stop (10; 110; 215; 315) comprising a end (11; 111,112; 211; 311) capable of coming to bear on a free end of the fingers during a disengaging movement of the disengaging bearing, characterized in that at least one of the end of the clutch release bearing and the free end of the fingers has at least two bearing surfaces (21,22; 111,112; 221,222; 321,322) separated substantially radially from one another and capable of coming successively into contact with each other from the end of the clutch release bearing and the free end of the fingers, during the clutch release movement stop.

2. Clutch device according to claim 1, characterized in that it comprises at least two friction discs.

3. Clutch device according to claim 2, characterized in that it comprises a second diaphragm able to cooperate with one of the two friction discs, the first diaphragm being able to cooperate with the other of the two friction discs .

4. Clutch device according to one of claims 1 to 3, characterized in that it comprises at least one wear take-up system (260).

5. Clutch device according to one of claims 1 to 4, characterized in that it is of the pushed type.

6. Clutch device according to one of claims 1 to 4, characterized in that it is of the pulled type.

7. Clutch device according to one of claims 1 to 6, characterized in that the clutch release bearing comprises a plate of substantially annular shape comprising the end (11; 111, 112; 211; 311) capable of coming onto the free end of the fingers during the release movement of the stop.

8. Clutch device according to claim 7, characterized in that the plate of substantially annular shape is mounted on the free end of the fingers of the diaphragm by fixing means (252, -352,353).

9. Clutch device according to claim 8, characterized in that the fixing means are clipping means (252).

10. Clutch device according to one of claims 7 to 9, characterized in that the plate of substantially annular shape has on an internal periphery a substantially vertical wall capable of partially enveloping the free end of the fingers of the diaphragm.

11. Clutch device according to one of claims 1 to 10, characterized in that the two bearing surfaces are arranged so that, during the disengagement movement, a change of contact from one to the other bearing surfaces takes place substantially at the end of the declutching movement, the declutching stop then entering a state of declutching overtravel.