WO2016055637A1 - Clutch device - Google Patents

Abstract

The invention relates to a clutch device (1) comprising a reaction plate (5) intended to be rotationally coupled to a driving shaft (8), a first friction disc (6a) mounted behind the reaction plate (5) and coupled to a first driven shaft (2), a first movable pressure plate (4a), able to be actuated so as to clamp or release the first friction disc (6a) to or from the reaction plate (5), characterized in that it comprises a support hub (21) rotationally coupled to the first driven shaft (2), the reaction plate (5) being mounted in a rotatable manner on the support hub (21), via a bearing (31), said reaction plate (5) being kept axially in position with respect to the support hub (21), the radially inner periphery of the first friction disc (6a) surrounding the support hub (21), the rear end of the support hub (21) extending behind the radially inner periphery of the first friction disc (6a), the rear end of the support hub (21) bearing against a pressing member (36) which is axially fixed with respect to the first driven shaft (2).

Description

 Clutch device

The present invention relates to a clutch device, such as for example a double clutch, in particular for a motor vehicle.

 A dual clutch allows in particular to alternately couple the motor shaft of the vehicle with two coaxial input shafts of a gearbox, which can be of the robotic type.

 Thus, a dual clutch allows to change gears while maintaining the transmission of a torque engine to the vehicle wheels. Indeed, the two clutches are respectively associated with even and odd gear ratios. During a gearshift, a first clutch is disengaged while the second clutch is engaged, so that the engine torque is progressively transferred from the first to the second clutch.

 Each clutch comprises a mechanism comprising a diaphragm for cooperating with a pressure plate integral in rotation with the cover and the motor shaft. Each diaphragm is movable by means of a corresponding clutch abutment, between a rest position and an active position. Depending on the type of clutch, the active position of the diaphragm corresponds to a coupling or decoupling of the shafts of the engine and the gearbox and the rest position of the diaphragm corresponds to a decoupling or a coupling of these shafts. These are respectively a normally open clutch and a normally closed clutch.

 For safety reasons, at least one of the clutches is of the normally open type.

The clutch stop is controlled by an actuator controlled by an electronic computer to exert a predetermined force on the diaphragm and move it over a given distance. The pressure plate of each clutch, biased by the corresponding diaphragm, is intended to clamp a friction disc on a corresponding reaction plate. A reaction plate may be provided for each clutch. Alternatively, a single reaction plate common to both clutches, mounted between the two friction discs, is used.

 Each friction disk is rotatably connected to an input shaft of the gearbox and each reaction plate is for example integral in rotation with a flywheel connected to the motor shaft. Thus, the clamping of a friction disk between the corresponding pressure and reaction plates allows the transmission of a torque between the drive shaft and the associated gearbox shaft.

 US 2008/0230342 discloses a dual clutch having a central reaction plate on either side of which are mounted a first and a second friction discs and associated pressure plates. Each pressure plate is actuated by a diaphragm, itself moved by an actuator of a clutch abutment.

 The reaction plate, the pressure plates, the friction discs, the diaphragms and the clutch stop are housed in a fixed clutch housing.

 In particular, the first friction disc is located axially behind the reaction plate, that is to say on the crankshaft side of the engine, while the second friction disc is located axially in front of the reaction plate, c that is to say on the side of the gearbox.

The first friction disk is rotatably coupled to a first shaft of the gearbox, also called a driven shaft, while the second friction disk is rotatably coupled to a second driven shaft, surrounding the first driven shaft. Each friction disc has an annular support bearing friction linings at its radially outer periphery and fixed to a hub at its radially inner periphery. The hub of each friction disc has splines cooperating with complementary splines of the corresponding driven shaft.

 The central reaction plate is pivotally mounted around the second driven shaft, i.e. around the larger diameter driven shaft, via a ball bearing.

 A circlip-type elastic ring makes it possible to hold the radially inner ring of the ball bearing axially in position on the second driven shaft. The elastic ring is mounted in a groove of the second driven shaft.

 Such a structure has the disadvantages described below.

First, the ball bearing has a large diameter since it is mounted around the second shaft that surrounds the first shaft. The weight and the cost of such a ball bearing are therefore also high.

 Moreover, given the dimensional tolerances of the various parts, such a structure requires to provide a travel or a large stroke of the actuators of the clutch release. Indeed, the position of the reaction plate is related to the position of the elastic ring forming an axial stop for the inner ring of the ball bearing supporting the reaction plate. Or the position of said elastic ring relative to the clutch housing (which defines the reference position) is determined by chains of dimensions intrinsic to the gearbox. It is therefore difficult to determine with great precision the position of the reaction plate. Therefore, the stroke of each actuator of the clutch abutment must integrate the different dimensional tolerances of the different parts forming the string of dimensions. Furthermore, it also implies that it is more difficult to determine the position of the licking point, from which a couple begins to be transmitted, which can affect the proper functioning of the double clutch.

In addition, the assembly comprising in particular the reaction plate, the friction discs, the pressure plates and the diaphragms can not be mounted directly in a single step on driven shafts, inside the clutch housing. Indeed, in such a case, the mounting of the elastic ring could not be performed later, since access to said elastic ring from the rear is prevented by the presence of the first friction disk, in particular by the hub of the first friction disc. At least a portion of the first friction disc must therefore be mounted after mounting the elastic ring on the second driven shaft, which makes such a mounting relatively tedious.

 The invention aims in particular to provide a simple, effective and economical solution to these problems.

 For this purpose, it proposes a clutch device comprising a reaction plate intended to be coupled in rotation to a driving shaft, a first friction disk mounted behind the reaction plate and coupled to a first driven shaft, a first plate mobile pressure device, operable to clamp or release the first friction disk on the reaction plate, characterized in that it comprises a support hub rotatably coupled to the first driven shaft, the reaction plate being mounted movably in rotation on the support hub, by means of a bearing, said reaction plate being held axially in position relative to the support hub, the radially inner periphery of the first friction disk surrounding the support hub, the rear end of the support hub; support hub extending behind the radially inner periphery of the first friction disk, the rear end of the support hub being supported on a support member which is axially fixed relative to the first driven shaft, the support member comprising an elastic ring.

Thus, according to the invention, the position of the reaction plate is directly dependent on the position of the support member, whose position can be for example easily determined or adjusted relative to a clutch housing, thus reducing the effect of dimensional tolerances. Moreover, the mounting of such a clutch device is relatively easy. Indeed, the rear end of the support hub being located behind the first friction disk, the support member can be positioned after assembly of the assembly formed at least by the reaction plate, the first friction disk and the first pressure plate on the first driven shaft.

 Preferably, the device may comprise a casing in which are mounted, at least in part, the reaction plate, the first friction disk, the first pressure plate and / or the first driven shaft, the position of the d support being determined axially with respect to a reference zone of the housing.

 The clutch device may comprise a wedge interposed axially between the elastic ring and the rear end of the support hub. The axial dimension of the shim can thus be chosen as a function of the position of the elastic ring relative to an area of a clutch housing, for example.

 In such a case also, the elastic ring and / or shim can be mounted in a groove of the first driven shaft.

 Furthermore, the clutch device may comprise a second friction disc mounted in front of the reaction plate and coupled to a second driven shaft surrounding the first driven shaft, and a second movable pressure plate, operable to tighten or release the second friction disc on the reaction plate.

 In addition, the inner periphery of the first friction disk can be rotatably coupled to the support hub, for example by means of splines.

 Finally, the support hub may comprise an abutment surface bearing on the rear end of the bearing, the front end of the bearing bearing on an abutment surface of the reaction plate.

The invention will be better understood and other details, features and advantages of the invention will become apparent on reading the following description given by way of non-limiting example with reference to the accompanying drawings in which:

 FIG. 1 is a view in axial section of a part of a clutch device,

 FIG. 2 is a detail view of a part of the FIG.

1,

 FIG. 3 is a half-view in axial section, illustrating a step of mounting the device of FIGS. 1 and 2,

 Figure 4 is a view corresponding to Figure 2, illustrating an embodiment of the invention.

 Figures 1 and 2 show a clutch device, in particular a double clutch 1 for a motor vehicle, for coupling a motor with a first and a second input shaft 2, 3 of a gearbox also called driven shafts . The double clutch 1 comprises first and second gearshift clutches of different ratios. The first shaft 2 is for example associated with the odd speeds reports while the second shaft 3 is for example associated with the reports of even speeds. The two shafts 2, 3 are coaxial, the first shaft 2 forming the inner shaft, the second shaft 3 being hollow and surrounding the first shaft 2.

 The first clutch comprises a first pressure plate 4a and a reaction plate 5 between which a first friction disk 6a extends. The first pressure plate 4a is rotatably coupled to the reaction plate 5 and is translatable relative thereto, between an engaged position and a disengaged position, in which it squeezes the first friction disc 6a on the platen. reaction 5 or respectively releases the first friction disc 6a.

The reaction plate 5 is fixed on a cover 7, itself intended to be coupled to the motor shaft or crankshaft 8 by means of damping means 9 such as for example a double damping flywheel. The first friction disc 6a is rotatably coupled to first shaft 2. Thus, in the engaged position of the first clutch, the crankshaft 8 is coupled to the first input shaft 2 of the gearbox.

 More particularly, the first friction disc 6a comprises an annular support 10a radially outer periphery of which are fixed friction linings 1 1a. The first friction disk further comprises two guide washers 12, 13 disposed on either side of an annular web 14. The guide washers 12, 13 are pivotally mounted relative to the annular web 14, elastic means such as, for example, curved or straight helical compression springs 15 extending circumferentially between the annular web 14, on the one hand, and the guide washers 12, 13, on the other hand. The elastic means 15 thus oppose the rotation of the guide washers 12, 13 with respect to the annular web 14 and form damping means. The support 10a is fixed to one of the guide washers 12, 13, more particularly to the front guide ring 12, that is to say to the guide ring located on the right in the figures.

 The radially inner periphery of the web 14 comprises splines 16 cooperating with complementary splines 17 formed in the front portion and on the radially outer surface of a hub 18 of the first friction disc 6a. Furthermore, the radially inner periphery of the hub 18 of the first friction disc 6a comprises splines 19 cooperating with complementary splines 20 formed at the radially outer periphery of a support hub 21. The inner periphery of the support hub 21 comprises splines 22 cooperating with complementary splines 23 of the first shaft 2. The annular web 14 of the first friction disc 6a is thus rotatably coupled to the first shaft 2 via the hub 18 of the first friction disc 6a and through the support hub 21.

The first pressure plate 4a is fixed on a cover 24 movable in translation relative to the reaction plate 5 and the cover 7, and extending forwardly. First elastic return tabs 25a are mounted between lugs of the first pressure plate 4a and lugs of the reaction plate 5.

 A first diaphragm 26a is pivotally mounted on the cover 7, by means of rivets 27 ensuring the centering of said diaphragm 26a while allowing it to tilt. The control of the first clutch is done by means of a first actuator 28a of a clutch abutment 29 cooperating with the radially inner periphery of the first diaphragm 26a via a thrust bearing 30a. The first diaphragm 26a forms a lever transmitting the force applied by the first actuator 28a to the first pressure plate 4a, via the movable cover 24.

 In order to allow effective clamping of the first friction disc 6a, the first diaphragm 26a is preloaded at rest. Without this pre-charge, the first diaphragm 26a would, at rest, in a state of elasticity requiring a start of travel of the relatively large first control stop to apply an effective clamping force on the first friction disc 6a. When the first actuator 28a is actuated, it balances the pre-charge of the first diaphragm 26a before starting the clamping of the first friction disc 6a. The preload of the first diaphragm 26a makes it possible to reduce the approach stroke of the first actuator 28a in order to clamp the first friction disc 6a, and to always have a minimum precharge force.

 The first clutch is of the normally open type. The rest position of the first diaphragm 26a therefore corresponds to a disengaged state of the first clutch. The first diaphragm 59a preferably has a portion of the Belleville washer type for returning the first diaphragm 26a to its rest position.

In the rest position of the first diaphragm 26a, that is to say when the first actuator 28a exerts little or no effort on the first diaphragm 26a, the first diaphragm 26a therefore does not exert (or little) effort on the first pressure plate 4a. The first plateau of 4a pressure is spaced from the reaction plate 5 via the resilient tongues 25a, so as to release the first friction disc 6a.

 The second clutch includes a second pressure plate 4b, and a second friction disk 6b extending radially between the reaction plate 8 and the second pressure plate 4b. The same reaction plate 5 is thus used for the two clutches, each friction disc 6a, 6b being disposed on the side of one of the two radial bearing faces of the reaction plate 5. Second elastic return tongues 25b are mounted between lugs of the second pressure plate 4b and lugs of the reaction plate 5.

 The second pressure plate 4b is rotatably coupled to the reaction plate 5 and is translatable relative thereto, between an engaged position and a disengaged position, in which it squeezes the second friction disk 6b on the platen. reaction 5, or respectively releases the second friction disc 6b.

 The second friction disc 6b is coupled to the second input shaft 3 of the gearbox. Thus, in the engaged position of the second clutch, the motor shaft 8 is coupled to the second input shaft 3 of the gearbox.

 A second diaphragm 26b is pivotally mounted on the cover 7. The second clutch is controlled by means of a second actuator 28b of the clutch abutment 29 cooperating with the radially inner periphery of the second diaphragm 26b, via a thrust ball bearing 30b.

 The second diaphragm 26b forms a lever transmitting the force applied by the second actuator 28b to the second pressure plate 4b, to allow effective clamping of the second friction disc 6b.

The second clutch is also of the normally open type. In the rest position of the second diaphragm 26b, i.e. when the second actuator 28b exerts little or no effort on the second diaphragm 26b, the second diaphragm 26b does not exert (or little) force on the second pressure plate 4b. The second pressure plate 4b is spaced apart from the reaction plate 5 by means of the elastic tongues 25b, so as to release the second friction disc 4b.

 As can be seen more clearly in FIG. 2, the reaction plate 5 is pivotally mounted around a front portion 21b of the support hub 21, via a bearing 31 such as for example a ball bearing comprising a radially inner ring 32 and a radially outer ring 33. The rear portion 21a of the support hub 21 is larger in diameter than the front portion 21b.

 The reaction plate 5 has a shoulder radially inner periphery, defining a bearing surface 34 facing rearwardly. The front end of the outer ring 33 of the bearing 31 bears on said bearing surface 34 of the reaction plate 5.

 Similarly, the rear portion 21b of the support hub 21 has a shoulder at the front end of said rear portion 21b, this shoulder delimiting a bearing surface 35 facing forward. The rear end of the inner ring 32 of the bearing 31 bears on said bearing surface 35 of the support hub 21.

 The rear end of the support hub 21 extends axially behind the radially inner periphery of the hub 18 of the first friction disc 6a and bears on the front face of a first nut 36 screwed into a threaded portion of the first shaft 2 A second nut 37 is screwed behind the first nut 36, so that the second nut 37 bears against the first nut 36 so as to form a lock nut.

The reaction plate 5, the pressure plates 4a, 4b, the friction discs 6a, 6b, the cover 7, the movable cover 24, the diaphragms 26a, 26b, the clutch abutment 29 and the driven shafts 2, 3 are housed, at least in part, in a clutch housing 38 in the form of a bell, visible in FIG.

 It is relatively easy to control the positions of the actuators 28a, 28b of the clutch stop 29 as a function of a reference zone of the clutch housing 38. In order to ensure the correct positioning of the reaction plate 5 with respect to the casing 38, it is necessary to control the position of the first nut 36 with respect to said clutch housing 38.

 For this purpose, as schematically illustrated in Figure 3, a positioning tool 39 can be used during assembly to ensure such positioning. This tool 39 has an annular shape and comprises a radially outer annular zone 40 extending radially, intended to bear on a surface or rear end 41 of the housing 38, said tool 39 further comprising a radially inner annular zone 42 extending radially, intended to form a radial bearing surface. A first screwing tool 43 comprises a bearing portion 44 comprising a radial bearing surface intended to bear against the opposite radial surface of the zone 42, the front end 45 of said screwing tool 43 engaging with the nut 36.

 The position of the bearing surface of the zone 42 of the positioning tool 39 being known with respect to the position of the bearing surface of the zone 40, it is possible to determine with precision the position of the first nut 36 relative to the casing 38.

 The second nut 37 can be screwed using a second screwing tool 43 ', coaxial with the first screwing tool 43 and engaged therein. The second nut is screwed until it bears on the first nut 36, so that the positions of the two nuts 36, 37 are maintained.

The assembly of the clutch device 1 can thus be obtained by mounting the assembly formed in particular by the reaction plate 5, the bearing 31, the pressure plates 4a, 4b, the friction discs 6a, 6b, the cover 7, the movable cover 24, and the diaphragms 26a, 26b on the driven shafts 2, 3, inside the clutch housing 38.

 The first nut 36 is then screwed onto the first shaft 2 by means of the positioning tool 39 and the first screwing tool 43. The second nut 37 is then screwed by means of the second screwing tool 43 'onto the first shaft 2, until it bears on the first nut 36. The damping means 9 can then be fixed to the lid.

 Such an assembly is therefore relatively simple, compared with the prior art, since the aforementioned assembly can be mounted in a single step on the shafts 2, 3.

 Furthermore, the bearing 31 being mounted on the first driven shaft 2, that is to say on the internal shaft, its diameter can be reduced, as well as its weight and cost. In addition, as indicated above, the positioning of the reaction plate 5 can be provided with precision, thus ensuring a better operation of the double clutch.

 FIG. 4 represents an embodiment according to the invention, which differs from that previously described in that the two nuts 36, 37 are replaced by a circlip-type elastic ring 46 and an adjustment wedge 47, mounted in a groove 2. The elastic ring 46 bears on the radial front face of the groove, the shim 47 bearing on the elastic ring 46 and the front end of the support hub 21 bearing on the shim 47. During assembly of such a clutch device, the operator may for example have a choice of shims 47 and thus choose a shim 47 whose axial dimension makes it possible to ensure the proper positioning of the support hub 21, and therefore of the reaction plate 5 with respect to the casing 38.

 As previously, the mounting of such a device 1 is relatively easy because the elastic ring 46 and the shim 7 can be mounted after assembly of the aforementioned assembly on the driven shafts 2, 3, inside the housing of clutch 38.

Claims

1. A clutch device (1) comprising a reaction plate (5) for rotationally coupling to a drive shaft (8), a first friction disk (6a) mounted behind the reaction plate (5) and coupled to a first driven shaft (2), a first movable pressure plate (4a), operable to clamp or release the first friction disc (6a) on the reaction plate (5), characterized in that it comprises a support hub (21) rotatably coupled to the first driven shaft (2), the reaction plate (5) being rotatably mounted on the support hub (21) via a bearing (31) said reaction plate (5) being held axially in position relative to the support hub (21), the radially inner periphery of the first friction disc (6a) surrounding the support hub (21), the rear end of the support hub (21), 21) extending rearwardly from the radially inner periphery of the first disc of fri ction (6a), the rear end of the support hub (21) bearing on a support member (36, 46, 47) which is fixed axially relative to the first driven shaft (2), the support member having an elastic ring (46).  2. clutch device (1) according to claim 1, characterized in that it comprises a housing (38) in which are mounted, at least in part, the reaction plate (5), the first friction disc ( 6a), the first pressure plate (4a) and / or the first driven shaft (2), the position of the support member (36, 46, 47) being determined axially with respect to a reference zone (41). ) of the housing (38). 3. clutch device (1) according to claim 1 or 2, characterized in that it comprises a shim (47) interposed axially between the elastic ring (46) and the rear end of the support hub (21). 4. clutch device (1) according to one of claims 1 to 3, characterized in that the elastic ring (46) and / or the wedge (47) are mounted in a groove of the first driven shaft (2) .  5. clutch device (1) according to one of claims 1 to 4, characterized in that it comprises a second friction disk (6b) mounted in front of the reaction plate (5) and coupled to a second shaft led (3) surrounding the first driven shaft (2), and a second movable pressure plate (4b), operable to clamp or release the second friction disk (6b) on the reaction plate (5) .  Clutch device (1) according to one of claims 1 to 5, characterized in that the inner periphery of the first friction disk (6a) is rotatably coupled to the support hub (21), for example by the intermediate splines (19, 20).  7. clutch device (1) according to one of claims 1 to 6, characterized in that the support hub (21) has an abutment surface (35) bearing on the rear end of the bearing (31). , the front end of the bearing (31) bearing on an abutment surface (34) of the reaction plate (5).