FR2804185A1 - Friction clutch for rotating electrical machine, such as motor vehicle alternator or starter motor, has reaction plate carrying machine rotor and friction plate linings carried by supports linked to springs - Google Patents

Abstract

The friction clutch has a reaction plate (20), designed to be connected to an arm and to carry a rotor (3) of the rotary electrical machine, such as the starter motor or alternator installed in the vehicle. A friction plate (6,7) has a friction lining (61,71) designed to engage with the reaction plate under the action of a clutch mechanism (14). The mechanism acts on the bottom (23) of a cover (15) solidly connected to the reaction plate, for acting on a pressure plate (13) rotatably connected with axial movement to the cover and reaction plate assembly. The friction lining is carried by supports (62,72) coupled by an set of springs (86) acting circumferentially on a hub (83) connected to an arm (8). The set of springs is movable axially in relation to the supports.

Description

The present invention relates to friction clutches comprising a reaction plate carrying a rotor of a rotary electrical machine, in particular for a motor vehicle.

The reaction plate is intended to be connected to a driving shaft and such a clutch further comprises at least one friction disc comprising at least one friction lining intended to come into contact with the reaction plate under the action of engaging means. bearing on the bottom of a cover intended to be secured to the reaction plate, for action on a pressure plate linked in rotation with axial mobility to the cover - reaction plate assembly, the friction lining being carried by a support coupled by elastic means with circumferential action to a hub, called an outlet, intended to be connected to a driven shaft.

Such a clutch is described for example in document DE-A-3 009 279. The electric machine is shaped to constitute an alternator and / or a starter for the engine of the motor vehicle in which the clutch reaction plate is stalled rotating on the crankshaft of the internal combustion engine.

According to this document, the clutch has a significant radial size, the elastic means with circumferential action being almost in the plane of the friction disc. The invention aims to provide a clutch of the above type whose radial size is significantly reduced.

According to the invention, a friction clutch, in particular for a motor vehicle, comprising a reaction plate intended to be linked to a driving shaft and carrying a rotor of a rotary electric machine, at least one friction disc comprising at least one lining friction intended to come into contact with the reaction plate under the action of engaging means bearing on the bottom of a cover intended to be secured to the reaction plate, for action on a pressure plate linked in rotation with axial mobility to the assembly constituted by the cover and the reaction plate, the friction lining being carried by a support coupled by elastic means with circumferential action to a hub, called an outlet, intended to be connected to a driven shaft, is characterized by the fact that said elastic means are offset axially relative to the support. Thanks to the invention, the elastic means can be installed radially over a larger average circumference, which is favorable for the transmission of the torque from the shaft leading to the driven shaft and / or for filtering vibrations.

Advantageously, the support is rigidly coupled to a hub integral in rotation with a coupling sleeve provided at one of its ends with a collar integral with two guide washers arranged on either side of a web, the elastic means with circumferential action acting between the web and the guide washers; the guide washers are secured together by posts passing through openings of the web with an angular play; the columns also serve to fix the guide washers to the external periphery of the flange of the coupling sleeve. This flange extends radially above the internal diameter of the friction lining (s).

Preferably, the elastic means with circumferential action are helical springs housed in windows made opposite in the web and the guide washers. Thanks to all these provisions, the web and the guide washers can extend over a larger circumference than the inside diameter of the friction lining (s). Advantageously, the pressure plate has a generally annular shape and surrounds the web and the guide washers.

Preferably, friction means with axial action intervene between the web and the guide washers; these friction means comprise a friction washer disposed axially between the web and a guide washer with which it is secured in rotation, an elastic washer with axial action being interposed axially between the friction washer and said guide washer; said guide washer is the guide washer, said internal, which faces the collar of the sleeve.

According to a first embodiment, the web is integral with the outlet hub. Alternatively, the web is elastically coupled to the outlet hub by means of a pre-damper, engagement means with circumferential clearance being provided between the inner periphery of the web and the outer periphery of the outlet hub. Thanks to the invention the pre-damper can have the desired radial size since the elastic means are implanted over a larger circumference.

Preferably, an annular part is placed axially between the veil and the other guide washer, being secured to the veil, helical springs being housed in windows made opposite in the annular part and an annular prominence that presents radially the output hub. Advantageously, the pre-damper comprises friction means with axial action; these friction means are constituted by the annular part provided in friction material and having an extension towards the axis in the form of a collar pinched axially between the outlet hub and the guide washer; the axial pinching is ensured by an elastic washer disposed axially between the other so-called internal guide washer and the outlet hub; a friction washer is disposed axially between the elastic washer and the outlet hub.

Advantageously, the clutch comprises two friction discs provided at their outer periphery with at least one friction lining carried by a support rigidly coupled to a hub, an intermediate pressure plate being disposed axially between the two friction discs.

Thus, the radial size of the clutch is further reduced because the number of friction surfaces is increased and, for the same torque to be transmitted, the size of these is reduced. This also makes it possible to easily accommodate the elastic means - pre-shock absorber assembly.

Preferably, the reaction plate is extended at its outer periphery by an annular skirt of axial orientation surrounding the two friction discs, the intermediate pressure plate and the so-called end pressure plate, said skirt externally carrying the rotor of the electric machine, the cover being fixed on the skirt; the cover has a hollow shape and has a transverse orientation bottom for support of the engagement means and a transverse orientation rim for fixing the cover to the free end of the skirt.

A clutch release bearing is provided for action on declutching means associated with the clutch means to counteract at will the action of the clutch means, the clutch release member belonging to a clutch release device of the concentric type intended to be crossed by a driven shaft.

This reduces the axial size between the bottom of a housing such as a clutch housing and the clutch, while having a rotor of great axial length.

The declutching device comprises, on the one hand, a piston carrying the declutching stop and mounted axially movable relative to a part, called the fixed part, having a blind annular cavity of axial orientation delimited by the piston to define a variable volume work.

Advantageously, the engaging and declutching means belong to a diaphragm comprising a peripheral part in the form of a Belleville washer, constituting the engaging means, extended by a central part constituting the declutching means, said central part being fragmented into radial fingers by blind slots, of which the bottoms form widened orifices at the internal periphery of the peripheral part.

Preferably, the pressure plates have at their outer periphery radial tabs engaged in grooves that the skirt has at its internal periphery.

Advantageously, the rotor extends, in the direction of the free end of the skirt, in axial projection relative to the friction discs; the skirt surrounds the end pressure plate.

Preferably, the rotor is mounted by hooping on the outer periphery of the skirt.

In application to a motor vehicle, the reaction plate constitutes a thickened portion of a drive wheel intended to be fixed on the output shaft of an internal combustion engine.

To better understand the object of the invention, we will now describe, by way of example, purely illustrative and not limiting, an embodiment shown in the accompanying drawings, in which - Figure 1 is a view in axial section of a clutch according to the invention; - Figure 2 is a partial view of Figure 1, on a larger scale.

Referring to the figures, we see a friction clutch 1 housed inside a fixed clutch bell 2 of a motor vehicle.

The clutch 1 has an axis of axial symmetry X-X around which it is rotatably mounted. This clutch 1 carries the rotor 3 of an electric machine 4 rotating around the axis X-X. The machine 4 is housed above the clutch 1 and has a stator 5 carried internally by the bell 2.

The stator 5 surrounds the rotor 4 while being located radially opposite it, so that a gap 50 exists between the internal periphery of the stator 5 and the external periphery of the rotor 4, the rotor 4 and the stator 5 being coaxial.

The stator 5 is provided with windings of electric wires of which one sees in 51 one of the updos. The clutch 1 is here of the two-disc type to reduce the radial size of the assembly constituted by the friction clutch 1 and the electric machine 4.

The clutch 1 therefore comprises two friction discs 6, 7; these discs 6 and 7 have at their outer periphery at least one friction lining 61, 71 intended to be clamped between two plates under the action of engagement means 14.

Declutching means 14 are provided to counteract at will the action of the clutch means under the action of a declutching stop 19 belonging to a declutching device 119 of the concentric type, in order to reduce the axial space requirement between the bottom of the bell 2 and clutch 1.

Indeed, the stop 19 could be actuated by a declutching fork pivotally mounted, for example by means of a ball joint, on the bottom of the bell 2 constituting a fixed part; such an arrangement increases the axial size because a travel of the fork is to be expected.

As described in document US-A-5 141 091, the declutching stop 19 can belong to a concentric declutching device with cable control, this stop being then mounted on a driven part movable in translation and fixed in rotation, said part being in relation to screw nut with a driving part fixed in translation and movable in rotation. The driving part carries a pulley on which the control cable is wound. For more details, see document US-A-5 141 091.

Alternatively, the driving part is controlled by a transverse electric motor.

Here, the concentric declutching device 119 is of the hydraulic type and comprises two parts in relation to the piston cylinder, namely a fixed part 120, delimiting a blind annular cavity 121 of axial orientation and a piston 122 mounted axially movable relative to the fixed part.

This piston 122 carries the declutching stop 19 and enters the cavity 121 to define therewith a working chamber of variable volume; the cavity 121 communicates by a channel not shown with a pipe connected to a master cylinder actuated by a clutch pedal or an actuator with an electric motor controlled according to programs predetermined by a computer. The working chamber is therefore allowed to be pressurized or depressurized, the control fluid filling said chamber usually being oil. The fixed part 120 may be in one piece of moldable material.

Here, the fixed part 120 comprises, for reduction of the radial size, two coaxial parts, namely an outer body surrounding a metal guide tube which is axially longer than the outer body. The bottom of the cavity 121 is delimited by a transverse rim belonging to the guide tube assembled to the external body using an intermediate assembly part. A static seal is provided between the outer body and the guide tube carrying at its free end a stop to limit the displacement of the piston 122 when the declutching device is not mounted on the bell 2. The channel communicates with a groove 123 opposite the edge of the guide tube.

A preload spring (not shown) acts between the external body of moldable material and the declutching stop 19 to maintain the latter in constant support on the declutching means 14 of the clutch 1. As a variant, the cavity can be delimited entirely by the tube - guide.

The declutching means 14 associated with the declutching means comprise declutching levers. These levers can act on helical springs with axial action constituting the engagement means. Alternatively, the release levers consist of fingers belonging to the central part of a part, the external periphery of which is either axially elastic, or devoid of axial elasticity for the formation of a false diaphragm acting on a Belleville washer forming the engagement means.

Here, the engagement and disengagement means belong to the same part called a diaphragm 14. This diaphragm 14 has a peripheral part in the shape of a Belleville washer, internally extended by a central part fragmented into radial fingers by blind slots opening internally into the central opening. that presents the diaphragm 14 of frustoconical shape in the free state. The slots open at their outer periphery into enlarged orifices 28 forming the bottom of the slots.

The fingers of the diaphragm 14 form declutching levers and therefore the declutching means, while the peripheral portion in the form of a Belleville washer, of the diaphragm 14 constitutes the clutch engaging means, the orifices 28 being located at the internal periphery of the Belleville washer of the diaphragm.

The clutch release bearing 19 comprises a ball bearing with a profiled rotating ring for punctual contact with the internal ends of the diaphragm fingers 14 and a non-rotating ring axially coupled to the piston 122, which thus carries the clutch release bearing 19. Here, the outer ring of the bearing is rotating, while the inner ring of the bearing is fixed in rotation and has at its internal periphery a radial flange bearing on a front shoulder of the piston 122, said flange being pressed against said shoulder by an elastic washer with action axial, here in the form of a Belleville washer, resting on the piston. The clutch release bearing 19 has a flag shape so that the inner ring of the ball bearing is intended to surround the reduced diameter front end of the outer body to reduce the axial bulk, the outer body being intended to be fixed. on the bottom of the bell 2, directly, using ears, or indirectly, using an adapter sole and a bayonet mount.

Here, the outer body has fixing lugs and the disengaging stop 19 is of the self-centering type because it can move radially in contact with the shoulder of the piston under the control of the elastic washer with axial action.

For more details, reference is made, for example, to document WO98 / 14713 showing the assembly of the external body with the guide tube. Of course, a protective bellows 124 is provided for good sliding of the piston 122.

Anyway, the declutching device 119 is of the concentric type and intended to be crossed by a driven shaft 8, namely here the input shaft of the gearbox. The declutching device 119 therefore surrounds the driven shaft 8. The friction discs 6, 7 have a hub 63, 73 centrally for rotationally connecting with the driven shaft 8 via a hub 83, called the outlet hub, as described below. -after. The friction lining 61, 71 is integral with a support 62, 72 rigidly coupled to the hub 63, 73.

The shaft 8 therefore passes through the declutching device 119 and the hubs 63, 73 of the discs. Usually, the end of the shaft 8 is received in a pilot bearing carried by the output shaft 11 of the internal combustion engine, namely here the crankshaft of the internal combustion engine of the vehicle. The tree 11 is therefore a leading tree.

The support 62, 72 can be embedded in the lining 61, 71. Here, two identical linings 61, 71 are arranged axially on either side of the support 62, 72, by being fixed to the latter by riveting, the support 62, 72 being shaped at its outer periphery to be axially elastic and to be progressively crushed.

As a variant, the fastening of the linings 61, 71 to the support 62, 72 is carried out, for example, by gluing, which makes it possible to remove fixing rivets and to reduce the axial size, since the dead thickness of the linings 61, 71 intended for the riveting operation is deleted. For example, the friction linings 61, 71 can be bonded directly in the central areas of the bearing surfaces of tripod blades described in the document FR-A-2 693 778 to which reference will be made for more details. In the embodiment shown, the friction clutch 1 comprises, in addition to the discs 6, 7 locked in rotation on the input shaft 8 of the gearbox, a rotary drive wheel 9 of hollow shape, an intermediate pressure plate 12, an end pressure plate 13, the diaphragm 14, a cover 15, tongues 18.

The flywheel 9, or flywheel, and the pressure plates 12, 13 are made of moldable material, here cast iron.

The cover 15 is metallic, here in stamped sheet metal. This cover has a bottom 23, generally of transverse orientation perpendicular to the axis of axial symmetry X-X, extended at its external periphery by a sinuous zone 24 for connection to an annular rim 25 for fixing.

The rim 25 has a transverse orientation and is offset axially and radially with respect to the bottom 23 which is perforated centrally.

The cover 15 therefore has the shape of a flat plate with a central hole. The bottom 23 is offset axially to the right of the figure with respect to the rim 25 extending radially above the bottom 23.

The flywheel 9 is intended to be fixed here centrally using screws 10, or any other fixing member, on the crankshaft 11 of the vehicle engine.

The flywheel 9 is of increasing thickness from its internal periphery to its external periphery, it is open centrally for its centering mounting on the crankshaft 11. At its internal periphery, the flywheel 9 has a central ring 26 provided with holes for the passage of the fixing screws 10.

 Radially, above the central ring 26, the flywheel 20 is thickened to form the reaction plate 20 of the clutch.

This plate 20 is, according to one characteristic, extended axially at its external periphery by an annular skirt 21 of axial orientation surrounding the linings 61, 71 of the friction discs 6, 7 and the pressure plates 12 and 13. The fixing flange 25 of the cover 15 is fixed on the free end of the skirt 21 by means of fixing members, here in the form of screws 22. The flange 25 is therefore perforated for the passage of the screws 22. The skirt 21 is here integrally with the plate 20 being obtained by molding.

So,. the discs 6, 7, the plates 12, 13 and the diaphragm 14 are housed inside the flywheel 9.

The skirt 21 therefore extends in axial projection relative to the plate 20, of which it is integral, and has internally axial grooves 33 forming mortises. In these grooves penetrate, axially sliding, projecting radial lugs 34, forming tenons, coming from the external periphery of the intermediate pressure plate 12, so called because it is interposed, here interposed, between the friction linings 61, 71 of the discs friction 6, 7, and the outer periphery of the end pressure plate 13. These plates 12 and 13 are therefore linked in rotation to the flywheel 9 by a connection of the tenons 34 - mortises 33 type, allowing them to move axially by flywheel ratio 9.

The end pressure plate 13 is axially interposed between the friction lining 71 concerned of the friction disc 7 and the diaphragm 14, mounted here in a tilting manner on the cover 15.

The end pressure plate 13 has at its external periphery an annular boss of axial orientation 32, directed towards the bottom 23 of the cover, for punctual contact with the external periphery of the Belleville washer of the diaphragm 14. This boss is split and came from molding with tray 13.

The internal periphery of the Belleville washer of the diaphragm 14 is pivotally or pivotally mounted between a primary support 27, here coming from the bottom 23 of the cover by stamping, and a secondary support constituted by a ring ring carried by lugs coming from the cover.

More specifically, the enlarged orifices 28, forming the bottoms of the slots in the diaphragm 14, are crossed axially by lugs 16 coming from the cover, the number of which depends on the applications.

Here, the plate 13 is coupled to the cover 15 by elastic tongues 18 with axial action allowing axial movement of the plate 13 relative to the cover 15.

The tongues 18 extend tangentially and are fixed at one of their ends by rivets 31 to the plate 13. This fixing is carried out on radial lugs 34 of the plate 13. At their other end, the tongues 18 are screwed on the annular rim 25 of the cover 15 by bolts 90.

Of course, the primary support 27 can consist of a rod. The secondary support may have another form and consist, for example, of a ring rolled at its outer periphery for formation of the secondary support, said ring being fixed on columns. The secondary support may also consist of a rod carried by the balusters. It can also consist of profiled heads of balusters; the heads are profiled in an arc of a circle and form the split secondary support and located opposite the primary support 27 as described in document FR-A-1 524 350. I1 can also consist of a stamped washer fixed on the balusters as visible in document DE-C-3 227 810.

As will be understood, the tongues 18 exert an elastic return action of the end plate 13 in the direction of the bottom 23 of the cover 15; the end plate 13 has a friction face for contact with the relevant lining 71 of the friction disc 7 frontally, while the intermediate pressure plate 12 has a friction face for contact with the friction linings 61 frontally and dorsally, 71 respectively of the disc 6 adjacent to the reaction plate 20 - and of the disc 7. The reaction plate 20 has a friction face dorsally for contact with the other friction lining 61 of the disc 6. Normally, the clutch is therefore engaged and the engine torque is transmitted from the driving shaft 11 to the driven shaft 8 via the clutch 1.

In this position, the Belleville washer of the diaphragm 14, that is to say the clutch engagement means, is in contact, on the one hand, at its internal periphery with the primary support 27, and, on the other hand, at its outer periphery with the boss 32 of the end plate 13. The diaphragm 14 therefore biases this plate 13 in the direction of the reaction plate 20 so that the friction linings 61, 71 of the friction discs 6 and 7 are clamped between the pressure plates 12, 13 and reaction 20.

The discs 6 and 7 are therefore driven in rotation so that the hubs 63, 73 coupled with the linings 61, 71 drive in rotation, as described below, the driven shaft 8.

In this position, the piston 122 of the declutching device is in the retracted position, upper part of the figure, and the cavity 121 is depressurized. When the cavity 121 is pressurized, the piston 122 moves to the left of the figure, lower part of this figure, and therefore drives the declutching stop 19, which then acts by pushing on the fingers of the diaphragm 14, to make rotate this one.

The diaphragm 14 then takes support on its secondary support. In this case, the load exerted by the diaphragm 14 on the plates 12 and 13 decreases and then vanishes, the end plate 13 then following the movement of the diaphragm 14 under the biasing action of the tongues 18 the friction linings 61 , 71 are then released and the clutch disengaged. The engine torque is then not transmitted.

When the cavity 121 is depressurized, the diaphragm 14 brings the piston 122 back and the linings 61, 71 are tightened progressively because the supports 62, 72 are axially elastic.

Here, the friction linings 61, 71 are coupled elastically to the outlet hub 83 for good filtration of vibrations.

To do this, the hubs 63, 73 of the discs 6, 7 are integral in rotation with a coupling sleeve 81 surrounding the shaft 8; the sleeve 81 is stepped; its end facing the crankshaft 11 carries external grooves with which cooperate complementary grooves formed on the inner surface of the hub 63 of the disc 6 the other end of the sleeve 81, of larger diameter than the previous one, is surrounded by the hub 73 of the disc 7 which it centers its free end is provided with a flange 82 with which the hub 73 is secured by screws 88.

The collar 82, in the form of a crown, is integral with two guide washers 84 arranged on either side of a web 85. The collar 82 here extends radially above the internal periphery of the linings 61, 71 .

Helical springs 86 are housed in windows made opposite in the web 85 and the guide washers 84, secured together by posts 87 passing through openings in the web 85 with an angular play.

The springs 86 are with circumferential action. The columns 87 also serve to fix the guide washers 84 to the external periphery of the collar 82 of the sleeve 81, by means of screws 89 which pass through them.

The collar 82, the guide washers 84, the web 85 are surrounded by the end pressure plate 13, of generally annular shape.

Friction means with axial action intervene between the web 85 and the guide washers 84 mounted movable in rotation relative to the web 85 against the action exerted by the springs 86; these friction means are here constituted by a friction washer 91 disposed axially between the web 85 and the guide washer 84, said internal, which faces the flange 82 of the sleeve 81; this friction washer 91 is rotated by said internal guide washer 84 thanks at least to an axial tab 92 which it has and which passes through an opening in the web 84 an elastic washer 93 with axial action is interposed axially between the washer friction 91 and the internal guide washer 84. Here several tabs 92 are provided.

Of course, other forms of elastic coupling can be envisaged.

The veil 85 could be integral with the hub 83.

Here, a torsional pre-damper operates between the web 85 and the outlet hub 83; circumferential clearance engagement means are provided between the inner periphery of the web 85 and the outer periphery of the outlet hub 83; moreover, an annular piece 94 of friction material is placed axially between the web 85 and the external guide washer 84; this part 94 is secured to the web 85 thanks to the axial lugs 95 which it has; the annular piece 94 surrounds an annular radial prominence 96 of the outlet hub 83; helical springs 97 are housed in windows made opposite in the annular part 94 and the annular prominence 96.

To these springs 97 of the pre-damper are associated friction means with axial action intervening between the web 85 and the outlet hub 83; they consist of an extension towards the collar-shaped axis 98 of the annular part 94; this collar extends between the external face of the outlet hub 83 and the internal face of the external guide washer 84, these two faces having generally complementary shapes.

Pinching of the collar 98 between these two faces is ensured by an elastic washer 100 disposed axially between the internal guide washer 84, which, as is known, is integral with the external guide washer 84, and a transverse face of the outlet hub 83 with the interposition of a friction washer 99, one axial tab 101 of which passes through an opening in the internal guide washer 84. Means of play clearance intervene between the web 85 and the hub 83. The play play means here consist of a toothing coming from the internal periphery of the web 85 and a toothing coming from the external periphery of the hub 83, the teeth of the web 85 penetrating in circumferential play in the notches delimited by two consecutive teeth of the hub 83 and vice versa . The collar 98 and the part 94 have housings facing each other, here notches for mounting the springs 97 of lower stiffness than the springs 86. For more precision, reference will be made to document FR-A-2 726 618 showing the indentations.

The springs 86, the web 85 and the guide washers 84 belong to a main torsional damper. Thus a damping device intervenes between the coupling sleeve 81 and the outlet hub 83.

This device has guide washers 84 and 85, the outer peripheries of which extend over a circumference of diameter greater than that of the internal diameter of the linings 61, 71. The same applies to the flange 82.

This is made possible by the fact that the elastic means are offset axially relative to the supports 62, 72.

Thanks to this, the pre-damper can have a larger radial size since the springs 86 can be installed on an average circumference of larger diameter.

For the record, the operation of the torsion damping device will be recalled. In a first phase, the springs 97 of the pre-damper are compressed, then the web 85 is movable in rotation relative to the outlet hub 83; in a second phase, the guide washers 84 move relative to the web 85, against the elastic means 86 during this second phase, intervene in axial friction, not only the friction washer 91, as described above, but also the collar 98 and the crown 99.

As can be seen, the clutch which has just been described has a very reduced radial size despite the presence of the electric machine 4 which surrounds it, it has four friction faces and the damping means are offset axially with respect to the discs of friction 6, 7. The pre-damper can be bulky axially and is housed with the damping device inside the plate 13.

In addition, such a clutch is easily mounted and dismountable. Thus, to dismantle it, it suffices, after having removed the clutch bell 2 which carries the stator 5 of the machine 4, to unscrew the screws 22 and to remove the assembly constituted by the cover 15, the plates 12 and 13 , the friction discs 6 and 7, including the damping means carried by the sleeve 81 and the hub 83, of course, this assembly is removable in itself thanks to the bolts 90 and to the screws 89 and 88.

This assembly having been dismantled, the screws 10 are accessible and the flywheel 9, equipped with the rotor 3, can be removed if necessary. The rotor 3 therefore has a large axial extent and it is the same for the stator 5. The machine 4 thus has good efficiency.

The rotor 3 comprises a pack of sheets 130, here made of soft iron. This package of sheets 130 is mounted by hooping on the outer periphery of the skirt 21 having at its free end a flange 131 projecting radially forming a stop for the rotor 3. The package of sheets 130 is therefore hot mounted by fitting on the periphery external of the skirt 21 until contact with the collar 131.

The annular sheets thus form an axial orientation crown mounted by hooping on the skirt 21.

The sheets can be isolated by oxidation or provided with insulators.

The stator 5 is formed, similar to the rotor 3, from a pack of annular sheets, here made of soft iron, reconstituting a crown of axial orientation. Notches are made in the sheets for the passage of windings of electric wires of which the protruding buns are seen at 51, the rotor 3 and the stator 5 being represented here in a schematic manner.

By injecting a controlled electric current into the stator windings, the electric machine 4 is transformed into a starter for the combustion engine of the vehicle.

For this, an electronic type control device is provided. The machine is here of the asynchronous electric motor type. Of course, the electric machine can be of the synchronous electric motor or other type. In general, when the internal combustion engine is running, the machine acts as an alternator. The internal combustion engine can be shut down at each stop and restarted using the machine. The machine can constitute an electric brake or provide additional energy to the internal combustion engine to assist it or prevent it from stalling.

As a variant, the rotor 3 is fixed to the external periphery of the skirt 21 by means of grooves or by fitting with cones. The rotor 3 is thus secured both in rotation and axially of the flywheel.

Of course, the rotor 3 can be fixed on the skirt 21 using screws bearing on a fixing washer, passing through the sheet pack 130 in a similar manner to that described in document DE-C-3 227 810. Elastic elements can also be used.

The stator 5 is fixed here by shrinking at its outer periphery on the bell 2. Any other form of fixing, such as screwing, is possible.

It will be appreciated that the method of fixing by shrinking favors the reduction of the radial bulk. It will also be noted that the dust from the friction linings 61, 71 does not run the risk of contaminating the electric machine 4 and disturbing its operation.

Here, the assembly constituted by the machine 4 and the clutch 1 has all the desired comfort functions, while being compact in the radial direction and having good performance. Of course, the clutch can be equipped with a wear take-up device in particular to compensate for the wear of the friction linings and to maintain the diaphragm in a constant position when the clutch is engaged.

In the example described and shown, the clutch is of the pushed type, the clutch release bearing 19 acting by pushing centrally on the diaphragm 14. As a variant, the clutch is of the pulled type; in this case, the clutch release bearing is coupled to a docking part acting behind the diaphragm and passing through the central opening of the diaphragm. The declutching operation is carried out by pulling, via the docking piece, on the fingers of the diaphragm; in this case also, the peripheral part of the Belleville washer of the diaphragm is in contact, at its external periphery, with a support carried by the cover and, at its internal periphery, with the boss of the pressure plate. For more details, reference will be made, for example, to document FR-A-2 606 477 also showing a wear take-up device, the boss 32 of the end pressure plate 13 being movable relative to said plate to compensate wear of the friction linings, circumferentially acting springs acting between the plate 13 and the boss 32, in combination with ramp means.

To better cool the reaction plate 20, it can be provided with ventilation fins at its front face turned away from the cover 15 and the discs 6, 7. Alternatively, the flywheel 9 can be provided holes, especially inclined, through. The cover 15 can have no rim and have a generally transverse orientation bottom, extended by an annular bush of axial orientation in intimate contact with the internal periphery of the skirt 21. The bush is then fixed on the skirt, for example by screws or any other means.

The cover 15 can be extended at its outer periphery to form an ignition target.

Of course, one of the supports 62 or 63 can be axially rigid and the other axially elastic. As a variant, the two supports are axially rigid.

Of course, one can provide more than two friction discs to further reduce the radial size. In this case, more than two intermediate pressure plates are provided.

The rotor 3 extends in the direction of the free end of the skirt 21, in axial projection relative to the friction linings furthest from the reaction plate 20; advantageously, the rotor 3 extends in the direction of the free end of the skirt 21, in axial projection relative to the friction lining 71 of the friction disc 7 furthest from the reaction plate 20.

The stop formed by the collar 131 may have another shape; this stop can be used for fixing by screwing the rotor 3. This rotor 3 can be provided with a squirrel cage with copper or aluminum parts. The skirt 21 is molded with the reaction plate 20. As a variant, it is attached to said plate 20, for example by screws.

Metal inserts can be housed in the steering wheel 9 to reinforce it. For example, the inserts, in section, have a square shape housed partly in the plate 20 and partly in the skirt 21.

As a variant, the inserts are of axial orientation, as described in document FR-A-2 718 806 to which reference will be made for more details. The inserts can be used to fix the cover 15. These inserts can protrude from the flywheel 9 and form targets, respectively for the electric machine and / or the engine ignition.

Of course, the flywheel 9 of moldable material may be based on aluminum. In this case, a coating of the friction face of the reaction plate 20 is provided for its cooperation with the lining 61.

Of course, the stop 131 can be replaced by inserts embedded in the skirt 21 and provided with a rim folded radially outward to form the latter. The inserts can protrude from the side of the face of the flywheel 9 facing outwards, that is to say opposite of the discs 6 and 7, and allow the rotor to be fixed with screws. 3. Of course, the inserts have holes or protrusions for good anchoring.

The machine 4 can be used to synchronize the speed of the shafts 8 and 11 when shifting gears. In this case, it is advantageous for the declutching stop 19 to be moved by a receiver 119, the transmitter of which is operated by an actuator controlled by a computer receiving information from sensors representing the speeds of the shafts 8 and 11.

It goes without saying that any type of electric machine with axial or radial magnetic flux may be suitable. The machine can be of the asynchronous type, as mentioned above, synchronous with magnet in the air gap or buried, with flux switching with single or hybrid magnets with excitations by stator windings, with brushless claws, with variable reluctance, with single or double excitation, with cross flow with Vernier effect.

The electric machine can be of the synchronous type with ring and brushes.

Claims (27)

<U> CLAIMS </U> 1. Friction clutch, in particular for a motor vehicle, comprising a reaction plate (20) intended to be connected to a driving shaft (11) and carrying a rotor (3) of a rotary electrical machine (4), at least one friction disc (6,7) comprising at least one friction lining (61,71) intended to come into contact with the reaction plate (20) under the action of engagement means (14) bearing on the bottom (23 ) a cover (15) intended to be secured to the reaction plate (20), for action on a pressure plate (13) linked in rotation with axial mobility to the assembly constituted by the cover (15) and the plate reaction (20), the friction lining (61, 71) being carried by a support (62, 72) coupled by elastic means (86) with circumferential action to a hub (83), called the outlet, intended to be connected to a driven shaft (8), characterized in that said elastic means (86) are offset axially with respect to the support (62,72). 2. Clutch according to claim 1, characterized in that the support (62,72) is rigidly coupled to a hub (63,73) integral in rotation with a coupling sleeve (81) provided at one of its ends of a flange (82) integral with two guide washers (84) arranged on either side of a veil (85), the elastic means (86) with circumferential action acting between the veil (85) and the guide washers (84). 3. Clutch according to claim 2, characterized in that the guide washers (84) are secured together by posts (87) passing through the openings of the web (85) with an angular play and by the fact that the posts (87 ) are also used for fixing the guide washers (84) to the external periphery of the flange (82) of the coupling sleeve (81). 4. Clutch according to claim 2 or 3, characterized in that the collar (82) extends radially above the internal diameter of the friction lining (s) (61, 71). 5. Clutch according to one of claims 2 to 4, characterized in that the elastic means with circumferential action are helical springs (86) housed in windows made opposite in the web (85) and the washers guide (84). 6. Clutch according to one of claims 2 to 5, characterized in that the pressure plate (13) is of generally annular shape and surrounds the web (85) and the guide washers (84). 7. Clutch according to one of claims 2 to 6, characterized in that friction means with axial action intervene between the web (85) and the guide washers (84). 8. Clutch according to claim 7, characterized in that these friction means comprise a friction washer (91) disposed axially between the web (85) and a guide washer (84) with which it is secured (92) in rotation, an axially acting elastic washer (93) being interposed axially between the friction washer (91) and said guide washer (84). 9. Clutch according to claim 8, characterized in that said guide washer (84) is the guide washer, said internal, which faces the flange (82) of the sleeve (81). 10. Clutch according to one of claims 2 to 9, characterized in that the web (85) is integral with the outlet hub (83). 11. Clutch according to one of claims 2 to 9, characterized in that the web (85) is elastically coupled to the outlet hub (83) by means of a pre-damper, meshing means with circumferential clearance being provided between the inner periphery of the web (85) and the outer periphery of the outlet hub (83). 12. Clutch according to one of claims 8 or 9 taken in conjunction with claim 11, characterized in that an annular part (94) is placed axially between the web (85) and the other guide washer (84) , by being secured (95) to the web (85), helical springs (97) being housed in windows made opposite in the annular part (94) and an annular prominence (96) that presents radially the outlet hub (83). 13. Clutch according to one of claims 11 or 12, characterized in that the pre-damper comprises friction means with axial action. 14. Clutch according to claims 12 and 13 taken together, characterized in that these friction means are constituted by the annular part (94) provided in friction material and having an extension towards the axis in the form of a collar (98) pinched axially between the outlet hub (83) and the guide washer (84). 15. Clutch according to claim 14, characterized in that the axial pinching is ensured by an elastic washer (100) disposed axially between the other guide washer (84) called internal and the outlet hub (83). 16. Clutch according to claim 15, characterized in that a friction washer (99) is arranged axially between the elastic washer (100) and the outlet hub (83). 17. Clutch according to one of claims 1 to 16, characterized in that it comprises two friction discs (6, 7) provided at their outer periphery with at least one friction lining (61,71) carried by a support (62,72) rigidly coupled to a hub (62,73), an intermediate pressure plate (12) being disposed axially between the two friction discs (6, 7). 18. Clutch according to claim 17, characterized in that the reaction plate (20) is extended at its outer periphery by an annular skirt of axial orientation (21) surrounding the two friction discs (6,7), the pressure plate (12) intermediate and the pressure plate (13) said end, said skirt (21) externally carrying the rotor (3) of the electric machine (4), the cover (15) being fixed on the skirt (21). 19. Clutch according to claim 18, characterized in that the cover (15) has a hollow shape and has a bottom (23) of transverse orientation for support of the engagement means (14) and a flange (25) of orientation transverse for fixing the cover (15) on the free end of the skirt (21). 20. Clutch according to one of claims 17 to 19, characterized in that a clutch release bearing (19) is provided for action on declutching means (14) associated with the clutch means (14) to counteract at will the action of the engagement means, the clutch release bearing (19) belonging to a clutch release device (119) of the concentric type intended to be crossed by a driven shaft (8). 21. Clutch according to claim 20, characterized in that the declutching device (119) comprises, on the one hand, a piston (122) carrying the declutching stop (19) and mounted axially movable relative to a part ( 120), said fixed part, having a blind annular cavity (121) of axial orientation delimited by the piston (122) to define a working chamber with variable volume. 22. Clutch according to one of claims 20 or 21, characterized in that the clutch means (14) and declutchers (14) belong to a diaphragm (14) comprising a peripheral part in the form of a Belleville washer, constituting the clutch means , extended by a central part constituting the declutching means, said central part being fragmented into radial fingers by blind slots, the bottoms of which form enlarged orifices (28) at the internal periphery of the peripheral part. 23. Clutch according to one of claims 18 to 22, characterized in that the pressure plates (12,13) have at their outer periphery radial tabs (34) engaged in grooves (33) that has the skirt ( 21) at its internal periphery. 24. Clutch according to any one of claims 18 to 23, characterized in that the rotor (3) extends, in the direction of the free end of the skirt (21), in axial projection relative to the discs friction (6,7). 25. Clutch according to claim 24, characterized in that the skirt (21) surrounds the end pressure plate (13). 26. Clutch according to any one of claims 18 to 25, characterized in that the rotor (3) is mounted by hooping on the outer periphery of the skirt (21). 27. Clutch according to any one of claims 1 to 26, characterized in that the reaction plate (20) constitutes a thickened portion of a drive wheel (9) intended to be fixed on the output shaft (11) of an internal combustion engine.