FR2915253A1 - CLUTCH DEVICE COMPRISING A DIAPHRAGM WHICH CONSTANTLY EXERCISES AXIAL PRECHARGE EFFORT ON A BEARING OF A REACTION PLATE - Google Patents

Abstract

The invention relates to a friction clutch device (10) comprising a reaction plate (22) rotatably mounted about an axis of rotation (B) via a bearing (24). and at least a first operative rear axial coaxial annular diaphragm (56) having resilient resilient fingers (60) between a forward clutch end position in which the first diaphragm (56) axially biases a first pressure plate (46). ) for clamping a first friction disk (52) against the reaction plate (22), and a rearward disengaging extreme position towards which the fingers (60) are resiliently biased, characterized in that, in their extreme rear position, the fingers (60) bear against a fixed and non-deformable mechanical element (96, 98) for exerting a first axial precharge force on said bearing (24) through the reaction plate (22).

Description

The invention relates to a friction clutch device which

  comprises a reaction plate which is rotatably mounted via a bearing. The invention relates more particularly to a friction clutch device, in particular for a motor vehicle, which comprises: - a reaction plate rotatably mounted around a rotary shaft via a bearing comprising a first ring axially connected to the shaft and a second ring connected to the reaction plate; at least one first pressure plate which is mounted to rotate with the reaction plate and which is slidably mounted axially with respect to the reaction plate; at least a first coaxial friction disc which is interposed axially between the reaction plate and the first pressure plate; At least one first actuating rear axial annular diaphragm which has flexible resilient fingers between an extreme front clutch position in which the first diaphragm axially urges the first pressure plate to clamp the first friction disc against the Reaction, and an extreme rear declutching position towards which the fingers are resiliently biased. This type of clutch device equips, for example, motor vehicles with a robotised gearbox in which the clutch device is actuated by an electronic control unit. For example, clutch devices of this type are known which comprise two driven shafts. The clutch device then comprises two temporary coupling means 2 each of which is intended to temporarily couple one of the driven shafts associated with the motor shaft. Thus, the clutch device comprises a reaction plate, two friction discs which are arranged on either side of the reaction plate which can be alternately clamped against the reaction plate by a first and a second plate pressure. Each pressure plate can be actuated by an associated diaphragm. In this type of clutch device, the fingers of the diaphragms are in a state of rest, that is to say that they are no longer energized, when they occupy their extreme rear declutching position. Furthermore, there is a regular degradation of the bearing which carries the reaction plate, degradation which may occur, for example, by plastic deformation when the bearing is a plain bearing, or by ball casting when the bearing is a bearing bearing. balls, because of the existing clearance between the inner ring and the outer ring. The degradation of the bearing is all the faster as the reaction disk rotates at a high speed. When the fingers of the diaphragm are in the extreme position before clutching, the diaphragm exerts an axial precharge force on the bearing via the pressure plate. But when the fingers of the diaphragm are in extreme rear position of disengagement, they are no longer energized. The diaphragm does not exert any axial preloading force on the bearing. In normal use, the fingers of one diaphragm do not occupy their extreme rear declutching position simultaneously with the fingers of the other diaphragm. However, it has been found that under certain conditions, the fingers of the two diaphragms are simultaneously in extreme rear declutching position while the reaction plate is rotated by the engine of the motor vehicle. The 3 stage then degrades rapidly, for example due to oscillation movements. This is particularly the case when the engine is running at high speed and that, following a malfunction, the electronic control unit must perform a reset of the clutch device by simultaneously bringing the fingers of the two diaphragms into their rearmost position. walkout. To solve this problem, it is known to preload the bearing by means of two preloading springs which are interposed between a control stopper of each diaphragm and a bearing face. Each preload spring thus exerts an axial precharge force on the bearing via the fingers of the associated diaphragm when they are in their extreme rear position. However, the axial preload force which is obtained by these springs, for example of the order of 70 to 100 N per preload spring, is insufficient to prevent the oscillation movements of the bearing. In addition, this design is expensive because it requires making and then mounting these preload springs. In addition, it is complex to precisely define the extreme rear position of the fingers of each diaphragm in so far as it depends on many parameters such as geometric tolerances, the stiffness of the preload spring, and the stiffness of the fingers of the diaphragm. diaphragm. To solve this problem in a simple and economical way, the invention proposes a friction clutch device of the type described above, characterized in that, when its fingers are in extreme rear position, the first diaphragm acts on the reaction plate. and its fingers are supported on a non-deformable mechanical element and axially fixed rearwardly relative to the first ring of the bearing to keep the fingers of the first diaphragm under tension 4 in their rearmost position so that the first diaphragm exerts a first axial forward preload force on the bearing through the reaction plate. The constant axial preload of the bearing makes it possible to limit its degradation. This axial precharge force also makes it possible to limit the oscillation movements of the reaction plate. According to other features of the invention: - the clutch device comprises a first actuating stop of the first diaphragm which is slidably mounted axially between an extreme front clutch position in which it biases the fingers of the first diaphragm in their extreme position before clutching and an extreme rear declutching position in which the fingers of the first diaphragm bear against the first actuating stop, the fingers of the first diaphragm being thus retained in their rearmost position of disengagement at against their elastic return force; the first actuating stop is carried by an axial sleeve which is mounted to slide axially on a guide, the sleeve being capable of abutting against a first radial fixed face of arrest in order to limit the stroke of the first actuating stop to its extreme rear position; the first actuating stop is controlled in displacement by a first axial actuating rod, the axial displacement of the first axial actuating rod being limited in one direction by a fixed stop face so as to limit the displacement towards the rear of the first actuating stop to its rearmost position so that the fingers of the first diaphragm are kept under tension in their rearmost position; - The movements of the first actuating stop are controlled by means of a first lever fork which is pivotally mounted about a transverse axis, the pivoting of the first fork being limited in one direction by a first fixed face. stopping so as to limit the rearward movement of the actuating abutment 5 to its rearmost position; the first pressure plate is interposed between the reaction plate and the first diaphragm, and the clutch device comprises a first radially outer rear annular cover which is carried by the reaction plate, the first diaphragm being fixed on the first diaphragm; cover, the first axial precharge force being applied to the reaction plate via the first rear cover; the clutch device comprises at least one second pressure plate which is mounted to rotate with the reaction plate and which is slidably mounted axially with respect to the reaction plate; at least one second coaxial friction disc which is interposed axially between the reaction plate and the second pressure plate; and at least one second operative rear coaxial annular diaphragm which has flexible resilient fingers between an extreme front clutch position in which the second diaphragm axially urges the first pressure plate to clamp the second friction disc against the platen. reaction, and an extreme rear declutching position towards which the fingers 25 are biased resiliently; when his fingers are in extreme rear position, the second diaphragm acts on the reaction plate and his fingers bear against a non-deformable mechanical element and axially fixed rearwardly relative to the first ring of the bearing 30 to maintain the fingers of the second diaphragm under tension in their extreme rear position so that the second diaphragm exerts a second axial forward preload force on the bearing through the reaction plate; 6 - the clutch device comprises a second actuating stop of the second diaphragm which is slidably mounted axially between an extreme forward clutch position in which it biases the fingers of the second diaphragm in their extreme forward clutch position and a position trailing rear extremity in which the fingers of the second diaphragm bear against the second actuating stop, the fingers of the second diaphragm thus being retained in their extreme rear declutching position against their elastic return force; the second actuating stop is carried by an axial sleeve which is mounted to slide axially on a guide, the sleeve being capable of abutting against a first fixed radial stop face to limit the stroke of the second actuating stop to its rearmost position; - The second actuating stop is controlled in displacement by a second axial actuating rod, the axial displacement of the second axial actuating rod 20 being limited in one direction by a fixed stop face so as to limit the displacement. towards the rear of the second actuating stop to its rearmost position so that the fingers of the second diaphragm are kept under tension in their rearmost position; The displacements of the second actuating stop are controlled by means of a second lever fork which is pivotally mounted about a transverse axis, the pivoting of the second fork being limited in one direction by a second face fixed stop so as to limit the rearward movement of the second actuating stop to its rearmost position; the second diaphragm is arranged behind the first diaphragm, the second diaphragm being capable of being in annular support on the first rear cover so as to exert the axial precharge force; the axial preloading force applied by the first diaphragm and / or the second diaphragm is at least equal to 5,400 N. Other characteristics and advantages will appear on reading the detailed description which follows, for the understanding of which FIG. 1 is an axial half-sectional view of a friction clutch device made according to a first embodiment of the invention, in which the fingers of the two diaphragms are shown in FIG. are in an extreme rear declutching position; FIG. 2 is a view similar to that of FIG. 1 in which the fingers of the first diaphragm are in an extreme forward clutch position while the fingers of the second diaphragm are in their rearmost disengaging position; FIG. 3 is a view similar to that of FIG. 1 in which the fingers of the first diaphragm are in their extreme rear declutching position while the fingers of the second diaphragm are in their extreme forward clutch position; FIG. 4 is a front view showing the means for actuating the diaphragms; - Figure 5 is a sectional view along the sectional plane 5-5 of Figure 4 which shows the actuating means of the first diaphragm; FIG. 6 is a sectional view along the sectional plane 6-6 of FIG. 4, showing the means for actuating the second diaphragm; 8 - Figure 7 is a view similar to that of Figure 1 which shows the clutch device made according to a second embodiment of the invention. In the following description, identical, similar or similar elements will be designated by the same reference numerals. FIG. 1 diagrammatically shows a portion of a friction clutch device 10, in particular for a motor vehicle, which is produced in accordance with the teachings of the invention. There is shown here the elements belonging to an upper half of the clutch device 10 because the clutch has a shape of revolution about its axis of rotation "B". In the remainder of the description, use will be made in non-limiting manner of an axial direction "A", along the axis of rotation "B" of the clutch device 10, oriented from the rear towards the front, which corresponds to at an orientation from right to left considering FIG. 1. Elements will be described as interior or exterior depending on their radial proximity to the axis of rotation "B". FIG. 1 shows a clutch device 10 which is intended to temporarily couple a motor shaft 12 which is arranged axially forward and of which a rear end is shown on the left in FIG. 1, with at least one 25 driven shaft 14. The drive shaft 12 is rotatable about an axis of rotation "B" and is rotated by a motor (not shown) of the motor vehicle. The clutch device 10 shown in FIG. 1 comprises two concentric driven shafts 14A, 14B which are rotatably mounted coaxially with the drive shaft 12. The first driven shaft 14A forms an axial tube within which the second drive shaft is arranged. driven shaft 14B. A free front end portion 9 of the second driven shaft 14B protrudes axially from the front end of the first tubular driven shaft 14A. Each of the driven shafts 14A, 14B is rotatable independently of the other.

  The driven shafts 14A, 14B are connected to a rear gearbox of which only a radial front end transverse wall is shown on the right in FIG. 1. For the following description, the front face 20 of the wall 18 of FIG. the gearbox will serve as a fixed reference point, so it will be referred to as the reference face 20. More particularly, the first driven shaft 14A corresponds to certain transmission speed ratios, for example the even gear ratios, while that the second driven shaft 14B corresponds to other gear ratios, e.g. odd gear ratios. The clutch device 10 comprises first means for temporary coupling of the first driven shaft 14A with the drive shaft 12. In known manner, the clutch device 10 comprises a circular radial reaction plate 22 which is rotatably mounted. around the axis of rotation "B", by means of a bearing, constituted in this example by a ball bearing 24. The ball bearing 24 is here interposed radially between the inner cylindrical face 26 of a central orifice of the reaction plate 22 and a front end portion 28 of the first tubular driven shaft 14A. The inner cylindrical face 26 of the reaction plate 22 has a radial rear end shoulder face 30 against which an outer ring 36 of the ball bearing 24 is intended to be axially supported. The front end portion 28 of the first driven shaft 14A also has a radial rear end shoulder 34 against which an inner ring 32 of the ball bearing 24 is to be axially supported rearwardly. An elastic ring 38 of the "circlip" type is also arranged in a groove of the first driven shaft 14A axially in front of the ball bearing 24. Thus, the inner ring 32 of the ball bearing 24 is axially locked in both directions. In this configuration, the inner ring 32 of the ball bearing 24 is rotated by the first driven shaft 14A, while the outer ring 36 of the ball bearing 24 is rotated by the reaction plate 22. The rings 32 , 36 are mounted with axial play with respect to the balls. To prevent the reaction plate 22 from rotating with an oscillating movement, the clutch device 10 is provided with means for preloading the ball bearing 24. The reaction plate 22 is thus substantially axially fixed with respect to the reference face 20 of the gearbox. Furthermore, the reaction plate 22 is rotatably connected to the drive shaft 12. For this purpose, the clutch device 10 comprises a flexible circular radial disk 40 which is arranged at a front end of the clutch device 10. and which is attached coaxially to the drive shaft 12. A radially outer front cover 42 is fixed on a rear face of the flexible disk 40 by means of a screw. The front cover 42 is mechanically connected in rotation to a peripheral portion 25 of the reaction plate 22. The flexible disk 40 comprises at its periphery a start ring 44. The clutch device 10 also comprises a first annular pressure plate 46 which is rotatably mounted to the reaction plate 22 about the axis of rotation "B". The first pressure plate 46 is more particularly arranged axially vis-a-vis a rear face 48 of the reaction plate 22. The first pressure plate 46 is slidably mounted axially relative to the reaction plate 22. Indeed, the first pressure plate 46 is mounted to slide axially on axial columns 50 which are fixed to the periphery of the reaction plate 22. The clutch device 10 also comprises a first coaxial friction disc 52 which is interposed axially between the reaction plate 22 and the first pressure plate 46. The first friction disk 52 has on both sides an annular friction lining 54 which is arranged axially opposite the first pressure plate 46. The first disk friction device 52 is intended to be clamped against the rear face 48 of the reaction plate 22 by the first pressure plate 46 to temporarily couple the first shaft 14A with the drive shaft 12. For this purpose, the first friction disc 52 is rotatably mounted to the first driven shaft 14A, and is mounted to slide axially on the first tubular driven shaft 14A between a tight front position against the first drive shaft 14A. rear face 48 of the reaction plate 22 and a free rear position towards which it is resiliently biased and in which the first friction disk 52 is moved away from the rear face 48 of the reaction plate 22. The axial clearance existing between the first disk friction 52 in its free rear position and the rear face 48 of the reaction plate 22 is very small and, by convention, it is not shown in Figure 1. The clutch device 10 also has a first diaphragm In the known manner, the first diaphragm 56 comprises a radially outer ring 58 and elastic fingers 60 extending radially towards the axis of rotation "B" from the ring 58 to a free inner end 62. All the fingers 60 are here identical. More particularly, the first pressure plate 46 is interposed between the reaction plate 22 and the first diaphragm 56. The first diaphragm 56 is supported on a first radially outer rear annular cover 64 which is fixed to the reaction plate 22. The rear cover 64 is thus fixed axially with respect to the reference face 20. The first rear cover 64 more particularly comprises an annular radial rear back 66 and a cylindrical axial skirt 68 which extends forward from the periphery of the bottom. 66 to the peripheral portion of the reaction plate 22 by surrounding the first pressure plate 46. The annular bottom 66 also has an axially projecting rib which is formed by an annular fold which is coaxial with the axis of rotation "B 15 and which extends axially rearwardly so as to have an annular ridge 70 projecting rearwardly. The ring 58 of the first diaphragm 56 is fixed on a front face of the bottom 66 of the first rear cover 64. The attachment is here made by an annular flange 72 which has tabs which extend radially inwards. The flange 72 is secured to the first rear cover 64 by rivets so that the ring 58 of the first diaphragm 56 is axially clamped against the bottom 66 of the first rear cover 64 by the radial tabs of the flange 72. An intermediate portion of each finger 60 of the first diaphragm 56 is axially supported on an annular portion 74 of the first pressure plate 46. The fingers 60 of the first diaphragm 56 thus function in the manner of a lever which is supported by its upper end against the first fixed rear cover 64. The fingers 60 of the first diaphragm 56 are elastically flexible between an extreme forward clutch position of the free end 62 of the fingers 60 which is shown in FIG. 13 and in which the first diaphragm 56 biases axially the first pressure plate 46 for clamping the first friction disk 52 against the reaction plate 22, and an extreme rear position of disengagement of the free end 62 of the fingers 60 to which the fingers 60 are resiliently biased and wherein the first pressure plate 46 is no longer biased axially so that the first friction disc is in its free rear position, as shown in FIG. Thus, in the extreme forward clutching position, the first driven shaft 14A is temporarily coupled to the drive shaft 12, and in the rearmost disengaging position, the first friction disk is moved away from the reaction plate 22 and the first pressure plate 46 so that the first driven shaft 14A is decoupled from the drive shaft 12.

  The first diaphragm 56 is for example made of a steel having suitable elastic properties. The clutch device 10 also comprises second temporary coupling means of the second driven shaft 14B with the driving shaft 12.

  The second coupling means thus comprise a second pressure plate 76 and a second friction disk 78 for the temporary coupling of the second driven shaft 14B with the drive shaft 12. The functions of the second pressure plate 76, respectively of the second friction disk 78 are similar to those of the first pressure plate 46, respectively of the first friction disc 52. The second pressure plate 76 is mounted axially vis-à-vis the front face 80 of the reaction plate 22. The second pressure plate 76 is rotationally integral with the reaction plate 22 via a second rear cover 82 which has a rear radial annular bottom 84 and a cylindrical axial skirt 86 which extends forward to second pressure plate 76 surrounding the first fixed rear cover 64. More particularly, the second rear cover 82 is attached to the periphery of the second platform at the pressure 76 by means of screws. The second pressure plate 76 is slidably mounted axially relative to the reaction plate 22. More particularly, the second rear cover 82 forms a slide which slides axially. The second sliding rear cover 82 is thus integral with the second pressure plate 76 in rotation and in axial sliding. The second coaxial friction disk 78 is interposed axially between the reaction plate 22 and the second pressure plate 76. It also comprises on its two faces an annular friction lining 88 which is interposed axially between the front face 80 of the reaction plate. 22 and the second pressure plate 76. The second friction disc 78 is intended to be clamped against the front face 80 of the reaction plate 22 by the second pressure plate 76 to temporarily couple the second driven shaft 14B with the drive shaft. 12. For this purpose, the second friction disk 78 is mounted to rotate with the second driven shaft 14B, and is axially slidably mounted on the front end portion 16 of the second driven shaft 14B between a rear position clamped against the face before 80 of the reaction plate 22 and a free front position to which it is resiliently biased in which the second friction disk 78 is remote from the front face 80 of the reaction plate 22. The axial clearance existing between the first friction disc 52 in its free rear position and the rear face 48 of the reaction plate 22 is very small and, by convention, it The clutch device 10 also includes a second rear axial coaxial diaphragm 90 for actuating the second pressure plate 76. The second diaphragm 90 has a structure similar to that of the first diaphragm 56. The second diaphragm 90 is arranged axially behind the first diaphragm 56. It is interposed axially between the edge 70 of the first fixed rear cover 64 and a front face of the bottom 84 of the second sliding rear cover 82. More particularly, the ring 92 of the second diaphragm 90 is arranged in axial support against a front face of the bottom 84 of the second sliding rear cover 82. An intermediate portion of the fingers 94 of u second diaphragm 90 bears axially backward on the edge 70 of the first fixed rear cover 64. The second diaphragm 90 is held in position by rivets which are fixed to the first rear cover 64. The rivets are more particularly arranged between two consecutive fingers 94 of the second diaphragm 90 with axial play. Thus, the second diaphragm 90 is held in position while allowing the fingers to bend 94.

  The fingers 94 of the second diaphragm 90 thus function as a lever. Thus, an axial actuation force which is applied forward to the free end 100 of the fingers 94 is transmitted to the cover 64, the fingers 94 bearing on the edge 70 of the first fixed rear cover 64, then to the plateau 22. The fingers 94 of the second diaphragm 90 are resiliently flexible between an extreme forward clutch position which is shown in FIG. 3 and in which the second diaphragm 90 biases the second pressure plate 76 axially towards the rear to press the first friction disk 52 against the reaction plate 22 via the second sliding rear cover 82, and an extreme rear declutching position to which the fingers 94 are elastically biased and in which the second pressure plate 76 is no longer axially biased so that the second friction disc 78 is in its free forward position, as shown in Figure 1. Thus, in positi the second driven shaft 14B is coupled to the drive shaft 12, and in the rearmost disengaging position, the second driven shaft 14B is decoupled from the drive shaft 12. As shown in FIGS. , the clutch device 10 also comprises means for independently controlling the first diaphragm 56 and the second diaphragm 90. As shown in more detail in FIG. 5, the control means comprise a first abutment 96 for actuating the first diaphragm 56 which is slidably mounted axially between an extreme front clutch position, as illustrated in Figure 2, in which it axially urges forward the free end 62 of the fingers 60 of the first diaphragm 56 in their extreme position before clutch and an extreme rear declutching position, as shown in Figure 3. As shown in more detail in Figure 6; the control means also comprise a second annular stop 98 for actuating the second diaphragm 90 which is slidably mounted axially between an extreme front clutch position in which it axially urges the free end 100 of the fingers 94 of the second diaphragm 90 in their extreme forward clutch position, as shown in FIG. 3, and an extreme rear declutching position, as illustrated in FIG.

  The first and second actuating stops 96, 98 are respectively fixed to a first and second sliding axial sleeve 102, 104.

The sleeves 102, 104 are slidably mounted on an axial tubular guide 106 which is secured by a rear end to the reference face 20 of the gearbox. For this purpose, the tubular guide 106 comprises a fastening collar 108 which extends radially outwardly from its rear end edge. Thus, the first sleeve 102 is slidably mounted inside the tubular guide 106 against an inner cylindrical face of the guide 106, while the second sleeve 104 is slidably mounted outside the tubular guide 106 on an outer cylindrical face of the Guide 106. Each stop 96, 98 can be slidably controlled by means of a generally radially lever-shaped fork 110, 112 which is pivotally mounted on an axial pivot 114 about a transverse axis 15 "C", "D". The pivot 114 associated with each fork 110, 112 extends axially projecting forwardly from the reference face 20. Each fork 110, 112 thus has an inner end 116 of axial support on the sleeve 102, 104 of the associated stop 96, 98, and an outer end 118 which is connectable to an actuating rod (not shown) axis "E" parallel to the axis of rotation "B". The inner ends 116 and outer 118 are arranged on either side of the pivot axis "C", "D" associated.

The movements of the fingers 60, 94 of each diaphragm 56, 90 is thus controlled by an associated transmission chain which comprises the associated actuating rod of an actuator, the associated fork 110, 112 and the associated abutment 96, 98. by its sleeve 102, 104.

In normal operation of the clutch device 10, the fingers 62, 94 of the diaphragms 56, 90 are alternately in their extreme forward clutch position. In the extreme forward clutching position of its fingers 62, 94, the diaphragm 18 56, 90 pushes the reaction plate 22 axially forward thereby producing the axial preload force of the ball bearing 24. However, in some situations, the fingers 62, 94 of the diaphragms 56, 90 are likely to be simultaneously in their extreme rear declutching position while the reaction plate 22 rotates. The ball bearing 24 is no longer preloaded, may deteriorate rapidly. According to the teachings of the invention, when its fingers 62, 94 are in the rearmost position, at least one of the diaphragms 56, 90 acts on the reaction plate 22 and its fingers 60, 94 are directly in contact with an element mechanical 96, 98 non-deformable and fixed axially rearwardly relative to the first ring 32 of the ball bearing 24 to hold the fingers 62, 94 of said diaphragm 56, 90 under tension in their extreme rear position. Said diaphragm 56, 90 thus exerts an axial forward preload force on the ball bearing 24 via the reaction plate 22 so that the contact between the rings 32, 36 and the balls is without axial play. In the embodiment shown in the figures, the two diaphragms 56, 90 jointly exert forward a first and a second axial preload force. The intensity of the axial preload force exerted by the diaphragms 56, 90 is proportional to the deflection of the fingers 60 relative to their unstressed position. For this purpose, and as will be described in more detail later, the clutch device 10 comprises a first and a second stop face 20, 108 which are fixed relative to the reaction plate 22 which are intended to block the axial displacement towards the rear of the stops 96, 98 of actuation in their extreme rear position. The actuating stops 96, 19 98 thus form the mechanical elements which are not deformable axially and axially fixed towards the rear. Each stationary stop face is arranged in the chain of transmission of the diaphragm 56, 90 associated so as to retain the fingers 60, 94 of the diaphragm 56, 90 associated in their extreme rear position against their elastic return force. The fingers 60, 94 of said diaphragm 56, 90 are thus kept under tension in their rearmost position so that each first and second diaphragm 56, 90 exerts a first and a second axial precharge force constantly associated forwards on the bearing. ball 24 through the reaction plate 22, especially when the fingers 60, 94 are in their extreme rear position. The first and second axial preloading forces are thus only produced by the elastic deformation of the fingers 56, 94 of the first and second diaphragms 56, 90. By axial preloading force, it will be understood that the intensity of the preload force axial, or the sum of the first and second axial precharge forces, is greater than a minimum intensity beyond which the balls are not likely to be deteriorated by matting, this intensity being a function of the plain bearing or the bearing used. The intensity of the axial precharge force formed by the sum of the first and second axial preload forces of the device produced according to the teachings of the invention is at least 400 N. Of course, the intensity of the axial preload force may also be higher depending on the dimensions of the clutch device. Thus, the axial preload force may, without limitation, be equal to 1600 N. The fact that the mechanical element is called "fixed axially rearward" means that in their extreme rear position, the stops 96 , 98 occupy a determined fixed reference geometric position with respect to the first inner ring 32 of the ball bearing 24. Thus, the rearward displacements of the stops 96, 98 are limited to their rearmost position even when the motor vehicle engine does not work. Thus, the axial preload force is applied even at the start of the motor vehicle. In addition, the rearmost position of the stops 96, 98 does not depend on the axial force applied to them, which advantageously simplifies the design of the clutch device 10. Thus, the clutch device 10 comprises a first face fixed stop for stopping the sliding back of the first actuating stop 96 in its rearmost position in order to constantly keep the fingers 60 of the first diaphragm 56 under tension so that the first axial preload force s' constantly exerts on the ball bearing 24. Indeed, as shown in Figure 1, when the fingers 60 of the first diaphragm 56 are under tension, their free end 62 bearing against the first stop 96 in its extreme rear position in abutment against the first fixed stop face, they apply to the ring 58 of the first diaphragm 56 an axial force forward. This force is directed forward as the first pressure plate 46 is free to slide axially. The first pressure plate 46 therefore does not form a fixed bearing point on which the fingers 60 of the first diaphragm 56 are capable of levering. The effort is not reversed. The axial precharge force is then transmitted to the fastening flange 72, then to the first fixed rear cover 64, then to the reaction plate 22 which itself transmits the axial precharge force to the outer ring 36 of the bearing. balls 24 via its shoulder face 30.

The clutch device 10 also includes a second stationary stop face to stop the second actuating stop 98 in its rearmost position in order to constantly keep the fingers 94 of the second diaphragm 90 under tension so that the second effort of axial preload is constantly exerted on the ball bearing 24. Indeed, as shown in Figure 1, when the fingers 94 of the second diaphragm 90 are under tension, their free end 100 bearing against the second stop 98 io of actuation in its extreme rear position, they apply to the first fixed rear cover 64 an axial force forward. The axial preload force is then transmitted to the reaction plate 22 which itself transmits the axial preload force to the outer ring 36 of the ball bearing 24 via its shoulder face 30. According to a first embodiment of the holding means, the rear end edge 120 of the axial sleeve 102 which carries the first stop 96 is capable of abutting against a first radial stop face to limit rearwardly the stroke of the first actuating stop 96 to its rearmost position. The first stationary fixed radial face is here formed by the fixed reference face 20 of the gearbox. Thus, in its extreme rear declutching position, the first actuating stop 96 holds the fingers 60 of the first diaphragm 56 in their extreme rear declutching position under tension against the restoring force of the fingers 60. In other words, the fingers 60 are supported by their free end 62 against the first actuating stop 96 which is stopped in its rearmost position by the fixed face of reference 20. In FIG. 1, the rear end 122 the sleeve 104 of the second stop 98 is also capable of abutting against a second fixed radial stop face which is here formed by the fixed front face of the flange 108 to limit backward the stroke of the second stop 98 actuation to its extreme rear position. Thus, in its extreme rear declutching position, the second actuating stop 98 retains the fingers 94 of the second diaphragm 90 in their rearmost position of release under tension against the restoring force of the fingers 94. other words, the fingers 94 are supported by their free end 100 against the second actuating stop 98 which is stopped in its rearmost position by the fixed front face of the flange 108. During operation of the clutch device 10 when the two actuating stops 96, 98 are in their rearmost disengagement position, as shown in FIG. 1, the fingers 60, 94 of the two diaphragms 56, 90 are under tension in their rearmost disengaging position in FIG. which their free ends 62, 100 are axially supported on the actuating stops 96, 98 which are respectively in abutment against the reference face 20 of the gearbox and control e the fixed front face of the flange 108. When the fingers 60 of the first diaphragm 56 are controlled to its extreme forward clutch position, as shown in FIG. 2, the actuating rod bears axially backwards against the outer end 118 of the first fork 110 (not shown in Figure 2). The first fork 110 pivots in a clockwise direction about its transverse axis "D" so that its inner end 116 axially urges the first actuating stop 96 forward. The latter urges the free end 62 of the fingers 60 of the first diaphragm 56 towards their extreme forward clutch position. The fingers 60 press axially forwards on the first pressure plate 46 by pressing on the first fixed rear cover 64. The first pressure plate 46 thus slides axially towards the reaction plate 22 so as to clamp the first disk in this configuration, the first diaphragm 56 exerts the first forward axial preload force via the first pressure plate 46, and the second diaphragm 90 still exerts the second axial preload force through the first fixed rear cover 64 being supported by the free end 100 of its fingers 94 against the actuating stop 98 in its extreme rear position. Then the fingers 60 of the first diaphragm 56 are controlled in their rearmost disengaging position as shown in Figure 1. The actuating rod then slides forward so as to allow the anti-clockwise rotation of the first fork 110. The fingers 60 of the first diaphragm 56 axially bear against the first stop 96 so that it moves to its rearward disengaging extreme position by pushing the inner end 116 of the first fork 110 which pivots in a direction counterclockwise. When the fingers 94 of the second diaphragm 90 are controlled to their extreme position before clutching, as shown in FIG. 3, the actuating rod bears axially backwards against the outer end 118 of the second fork 112. The second fork 112 pivots about its transverse axis "C" so that its inner end 116 axially urges the second actuating stopper 98 forward. The latter axially urges forward the free end 100 of the fingers 94 of the second diaphragm 90 to their extreme position before clutch. The fingers 94 of the second diaphragm 90 are supported axially forwardly by their intermediate portion on the edge 70 of the first fixed rear cover 64. By lever effect, the ring 92 of the second diaphragm 90 exerts then axially urges towards rearwardly the second sliding rear cover 24 82. The second pressure plate 76 thus slides axially towards the reaction plate 22 so as to clamp the second friction disc 78. In this configuration, the second diaphragm 90 exerts the second pressure forward axial preloading via the first fixed rear cover 64, and the first diaphragm 56 always exerts the first axial precharge force through the first fixed rear cover 64 by being supported by the free end 62 of its fingers 60 against the first stop 96 in its extreme rear position. According to a second embodiment of the invention which is shown in FIG. 7, the pivoting of the second fork 112 is limited in a counter-clockwise direction by a radial stop face which is here formed by the reference face 20 of the gearbox so as to limit the movements of the second actuating stop 98 to its rearmost position. Thus, the second fork 112 being pivotally locked against the reference face 20, the displacement towards the rear of the second stop 98 is blocked by the inner end 116 of the second fork 112 to its rearmost position. declutching in which the fingers 94 of the second diaphragm 90 are under tension. In their extreme rear position, the free end 100 of the fingers 94 of the second diaphragm 90 thus bear against the second actuating stop 98 which is in abutment in its extreme rear position against the fixed reference face 20 by the intermediate of the second range 112. Although this is not shown, the pivoting of the first fork 110 may also be limited by the reference face 20 so as to limit the movements of the first stop 96 of actuation, and therefore fingers 60 of the first diaphragm 56, to their rearmost position.

According to a third non-illustrated embodiment of the invention, a first axial actuation rod controls the first stop, either directly or via a fork. The movements of the first axial actuating rod are then limited forwardly so as to limit the displacement of the first stop or the pivoting of the first fork in a counterclockwise direction by looking at FIG. 1 when the stop is controlled. in its extreme rear declutching position. The rearward displacement of the first actuating stop is thus limited to its rearmost position. When the fingers of the first diaphragm are in their rearmost position, their free end is thus in abutment against the first actuating stop which abuts against the first fixed stop face via the first fork and the first actuating rod. This third embodiment is also applicable to the second range 112. Of course, it is possible to combine several of these embodiments by implementing a first embodiment of the invention to limit rearward movements. the first actuating stop 96 and implementing another embodiment of the invention to limit the rearward displacements of the second actuating stopper 98. According to a variant not shown of the invention, the friction discs 52 may be replaced by an axial stack of several friction discs that are immersed or not in the oil, of the type commonly used in motorcycles.

According to a variant not shown of the invention, the clutch device 10 has only one driven shaft 14. The clutch device 10 then comprises only the first temporary coupling means, that is to say that is, a single pressure plate 46, a single friction disk 52 and a single actuation diaphragm 56. For example, by analogy with Figure 1, the clutch device 10 has no second pressure plate 76 or second friction disc 78, or second diaphragm 90 actuation.

Claims (14)

  1. Clutch device (10) friction, in particular for a motor vehicle, which comprises: - a reaction plate (22) rotatably mounted around a rotary shaft (14A) via a bearing ( 24) having a first ring (32) axially connected to the shaft (14A) and a second ring (36) connected to the reaction plate (22); at least one first pressure plate (46) which is mounted to rotate with the reaction plate (22) and which is axially slidable relative to the reaction plate (22); at least one first coaxial friction disc (52) interposed axially between the reaction plate (22) and the first pressure plate (46); At least one first operating rear axial coaxial diaphragm (56) which has resilient flexible fingers (60) between an extreme front clutch position in which the first diaphragm (56) axially biases the first pressure plate (46); ) for clamping the first friction disk (52) against the reaction plate (22), and a rearward disengaging extreme position towards which the fingers (60) are biased resiliently; characterized in that, when its fingers are in extreme rear position, the first diaphragm (56) acts on the reaction plate (22) and its fingers (60) bear against a non-deformable and fixed mechanical element (96) axially rearwardly relative to the first ring (32) of the bearing (24) to hold the fingers (60) of the first diaphragm (56) under tension in their rearmost position so that the first diaphragm (56) exerts a first axial forward preloading force on the bearing (24) via the reaction plate (22).   2. Clutch device (10) according to the preceding claim, characterized in that it comprises a first stop 28 (96) for actuating the first diaphragm (56) which is slidably mounted axially between an extreme front position clutch in which it urges the fingers (60) of the first diaphragm (56) in their extreme forward clutch position and an extreme rear declutching position in which the fingers (60) of the first diaphragm (56) rest on the first stop (96) actuation, the fingers (60) of the first diaphragm (56) thus being retained in their extreme rear declutching position against their elastic return force.   3. clutch device (10) according to the preceding claim, characterized in that the first stop (96) of actuation is carried by an axial sleeve (102) which is mounted to slide axially on a guide (106), the sleeve (102) being capable of abutting against a fixed first radial stop face (20) to limit backward the stroke of the first actuating stop (96) to its rearmost position.   4. clutch device (10) according to claim 2, characterized in that the first stop (96) of actuation is controlled in displacement by a first axial actuating rod, the axial displacement of the first axial rod of actuation being limited in one direction by a fixed stop face so as to limit the rearward movement of the first actuating stop (96) to its rearmost position so that the fingers (60) of the first diaphragm (56) are kept under tension in their rearmost position.   Clutch device (10) according to claim 2, characterized in that the displacements of the first actuating stop (96) are controlled by means of a first lever fork (110) which is pivotally mounted. around a transverse axis (D), the pivoting of the first fork (110) being limited in one direction by a first fixed stop face (20) so as to limit the displacement towards the rear of the stop ( 96) to its rearmost position.   Clutch device (10) according to one of the preceding claims, characterized in that the first pressure plate (46) is interposed between the reaction plate (22) and the first diaphragm (56), in that it comprises a first radially outer rear annular cover (64) which is carried by the reaction plate (22), and in that the first diaphragm (56) is fixed on the first cover (64), the first force axial preload being applied to the reaction plate (22) via the first rear cover (64).   7. clutch device (10) according to any one of the preceding claims, characterized in that it comprises: - at least a second pressure plate (76) which is mounted integral in rotation with the reaction plate (22); ) and which is slidably mounted axially with respect to the reaction plate (22); at least one second coaxial friction disk (78) which is interposed axially between the reaction plate (22) and the second pressure plate (76); at least one second actuating rear axial annular diaphragm (90) which comprises resilient flexible fingers (94) between an extreme front clutch position in which the second diaphragm (90) axially biases the first pressure plate (76); ) for clamping the second friction disk (78) against the reaction plate (22), and a rearward disengaging extreme position to which the fingers (94) are biased resiliently. 30   8. clutch device (10) according to the preceding claim, characterized in that, when his fingers (94) are in extreme rear position, the second diaphragm (90) acts on the reaction plate (22) and his fingers ( 94) are supported on a non-deformable mechanical element (98) and fixed axially rearwardly with respect to the first ring (32) of the bearing (24) to hold the fingers (94) of the second diaphragm (90) under tension in their extreme rear position so that the second diaphragm (90) exerts a second axial forward preload force on the bearing (24) through the reaction plate (22).   9. A clutch device (10) according to the preceding claim, characterized in that it comprises a second stop (98) for actuating the second diaphragm (90) which is slidably mounted axially between an extreme front position clutch in which it urges the fingers (94) of the second diaphragm (90) in their extreme forward clutch position and an extreme rear declutching position in which the fingers (94) of the second diaphragm (90) bear against the second stop (98) of actuation, the fingers (94) of the second diaphragm (90) thus being retained in their extreme rear declutching position against their elastic restoring force. 20   10. clutch device (10) according to the preceding claim, characterized in that the second stop (98) of actuation is carried by an axial sleeve (104) which is mounted to slide axially on a guide (106), the sleeve (104) being capable of abutting against a fixed first radial stop face (108) to limit rearwardly the stroke of the second actuating stop (98) to its rearmost position.   11. clutch device (10) according to claim 9, characterized in that the second stop (98) of actuation is controlled in displacement by a second axial actuating rod, the axial displacement of the second axial rod d actuation being limited in one direction by a stationary stop face so as to limit the rearward movement of the second actuating stop (98) to its rearmost position so that the fingers (94) of the second diaphragm (90) are kept under tension in their rearmost position.   12. clutch device (10) according to claim 9, characterized in that the movements of the second stop (98) of actuation are controlled by means of a second fork (112) forming lever which is pivotally mounted around a transverse axis (C), the pivoting of the second fork (112) being limited in one direction by a second fixed stop face (20) so as to limit the rearward movement of the second stop ( 98) to its rearmost position.   13. A clutch device (10) according to the preceding claim taken in combination with claim 5, characterized in that the second diaphragm (90) is arranged behind the first diaphragm (56), and in that the second diaphragm (56) ( 90) is capable of being in annular support on the first rear cover (64) so as to exert the axial precharge force.   14. Clutch device according to any one of the preceding claims, characterized in that the axial preload force applied by the first diaphragm (56) and / or the second diaphragm (90) is at least equal to 400 N.