FR3073912A1 - CLUTCH MECHANISM SUB-ASSEMBLY AND NORMALLY OPEN CLUTCH MECHANISM COMPRISING SUCH A SUBSET - Google Patents

Abstract

- a normally open clutch mechanism subassembly, comprising a diaphragm (1.2) housed in a cover (2.2) having a side wall (2b) and a bottom (2a) whose inner face bears a projection (3.3) on which said diaphragm bears, characterized in that said diaphragm (1.2) carries, on its outer peripheral edge, at least two support lugs (1.21) which extend radially and whose free ends are engaged, under stress of 'force in pivoting openings (2.21) which are formed in the side wall (2b) of said cover and, - a normally open clutch mechanism and a double clutch mechanism comprising such a subassembly and a hybrid transmission system equipped with said mechanism.

Description

CLUTCH MECHANISM SUB-ASSEMBLY AND NORMALLY OPEN CLUTCH MECHANISM COMPRISING THIS SUB-ASSEMBLY The invention relates to a clutch mechanism sub-assembly for a motor vehicle, to a normally open clutch mechanism comprising this sub-assembly and to a double-clutch mechanism comprising, in particular, such a sub-assembly.

More generally, the invention relates to an improvement of a subassembly consisting of the diaphragm and the cover intended for normally open clutch mechanisms for motor vehicles and, in particular, for double-clutch mechanisms for gearbox transmission systems automatic so-called robotic and also with so-called “KO cut-off” clutch mechanisms for hybrid transmission systems.

PRIOR ART [0003] A traditional clutch mechanism generally comprises, on an axis of revolution, a cover in which is housed an annular diaphragm tilting between a engaged position and a disengaged position so as to move a pressure plate.

The pressure plate, biased by the diaphragm, is intended to clamp a friction disc carrying friction linings on a reaction plate coaxial with the pressure plate and the friction disc.

The diaphragm generally has an annular shape and carries, in its central part, fingers extending radially inwards. This diaphragm is mounted on the cover by means of rivets ensuring its retention while allowing its elastically reversible tilting.

The friction disc is linked in rotation to the input shaft of the gearbox while the reaction plate is rotationally secured to the cover, the diaphragm and a flywheel linked to the motor shaft. Thus, the tightening of a friction disc between the pressure and reaction plates allows the transmission of a torque between the motor shaft and the gearbox input shaft.

There are, moreover, so-called double-clutch mechanisms intended to be fitted more particularly to vehicles with a robotized gearbox. In these mechanisms, the two clutches are each connected to a gearbox shaft. Their respective diaphragms are mounted with freedom of tilting inside separate covers while their pressure plates are fixed, for example, on either side of a single intermediate reaction plate. This double-clutch mechanism makes it possible to change gear ratios without interrupting the transmission of engine torque to the vehicle's wheels.

The two clutches are normally open, which means that the passage into the engaged position and the transmission of the engine torque requires applying a force to bring the friction linings of each clutch into contact with the flywheel via the reaction plate. , unlike normally closed clutches in which this force is applied to the clutch. In a normally open clutch, the active position of the diaphragm therefore corresponds to a coupling of the engine shafts and the gearbox.

Such a double-clutch mechanism is known, in particular, from WO 2015/180778, in which a first diaphragm is housed between an outer cover and an inner cover containing a second diaphragm, the two covers being offset axially. The first diaphragm is supported both on a first projection carried by the inner face of the outer cover and a second projection carried by the outer face of the inner cover.

The second diaphragm is, in turn, supported on a third projection provided on the inner face of the inner cover as well as on an elastic washer called preload. This washer is mounted between the periphery of the second diaphragm and the pressure plate of the second clutch. The washer is riveted to the inner cover and forms a pivot between the disengaged position and the licking point while blocking the axial translation of the second diaphragm.

In the engaged position, the second diaphragm is supported on the third projection of the inner cover and on the support cord of the pressure plate of the second clutch so that the engine torque is transmitted to the second drive shaft.

In the disengaged position, the second diaphragm is supported on the third projection of the cover and on the preload elastic washer.

However, this preload washer is an additional independent part which requires a delicate assembly operation and which also contributes, by its own dimensions and mass, to increase the volume and the weight of the clutch mechanism. .

Furthermore, the two components of these clutch mechanisms that are the cover and the diaphragm, are generally pre-assembled in the factory to form a sub-assembly which is stored then transported and delivered to the assembly sites of the manufacturers. automobiles for integration into vehicle transmission systems.

PRESENTATION OF THE INVENTION The invention aims to remedy these technical problems by proposing an improved sub-assembly comprising a diaphragm and a cover on which the pivot of said diaphragm is formed, thereby freeing itself from the preloading washer. The refinement of the invention applies, in particular, to the diaphragm and to the cover of the second mechanism of a double-clutch mechanism, but can also be advantageously integrated into simple clutch mechanisms of the normally open type.

This object is achieved by means of a normally open clutch mechanism subset, comprising a diaphragm housed in a cover having a side wall and a bottom, the inner face of which carries a projection on which said diaphragm comes support, characterized in that said diaphragm carries, on its outer peripheral edge, at least two support lugs which extend radially and whose free ends are engaged, under stresses of force, in openings forming counter-supports which are provided in the side wall of said cover.

Advantageously, the stress of effort eliminates the micromovements generated by the diaphragm on the openings when the subassembly is subjected to the vibrations of the internal combustion engine. This force constraint is comprised, in the engaged position, between 100 and 400 N.

According to a specific variant, the openings of the cover are each formed by an orifice into which opens the end of the support legs of the diaphragm, said orifice ensuring the setting under stress of force of said legs between two faces, the forms a stop for the disengaged position of the diaphragm.

According to a characteristic of this variant, the wedging orifice is delimited by a circumferential wall, the inner face of which forms the stop for the support legs of the diaphragm in the disengaged position.

For example, the circumferential wall may be an attached blade and fixed on the edge of the side wall of the cover.

For example, the insert blade can completely cover the orifice.

According to another specific variant, the openings of the cover have a bayonet profile consisting of an open notch allowing the introduction of the end of the support legs and opening out laterally into an orifice ensuring the setting under constraints of force of said tabs between two faces, one of which forms a stop for the disengaged position of the diaphragm.

Preferably, the timing hole extends perpendicular to said open notch.

According to a characteristic of this other variant, the wedging orifice is delimited by a circumferential wall, the inner face of which forms the abutment of the support legs of the diaphragm in the disengaged position.

According to a first embodiment of the invention, the circumferential wall is an attached blade and fixed on the edge of the side wall of the cover.

The insert blade can partially cover the notch in the openings of the bayonet profile cover.

According to another embodiment, the circumferential wall is produced by deformation of a flank carried by the edge of the cover.

Preferably, the diaphragm comprises an annular part and support tabs distributed circumferentially around the annular part, the support tabs extending radially from said annular part.

Preferably, the diaphragm comprises actuating fingers, coming from the annular part, extending radially inwards and capable of coming to bear on a control stop.

According to a specific alternative embodiment of the invention, the periphery of the diaphragm is provided with petals, at least some of which bear said support legs.

According to an advantageous characteristic, the support legs have a tapered profile.

A second object of the invention is a normally open clutch mechanism characterized in that it comprises a sub-assembly as defined above and a pressure plate carrying a support cord bearing on the diaphragm.

According to a characteristic of this mechanism, the diaphragm comprises an annular part disposed, at least partially, between a projection of the cover and the support bead of the pressure plate and from which said support tabs extend radially beyond said projection.

Another object of the invention is a double-clutch mechanism comprising a first diaphragm housed between an outer cover and an inner cover containing a second diaphragm, the two covers being axially offset, characterized in that the inner cover and the second diaphragm consist of a subset as defined above.

Yet another object of the invention is a hybrid transmission system comprising a normally open clutch mechanism as defined above, an electric motor and a double-clutch mechanism having the characteristics defined above.

The invention makes it possible to secure the diaphragm in the cover under stresses of effort and thus to produce a stable sub-assembly, well suited to storage and ready for an easy operation of subsequent integration into a mechanism d 'clutch.

Thanks to the invention, it becomes possible to dispense with the elastic preloading washer which makes it possible to lighten the clutch mechanism and reduce its size while providing a significant gain in material. Advantageously, between the disengaged position and the engaged position, the diaphragm is constantly subjected to an axial force. The micro-movements of the diaphragm with respect to the supports of the cover are thus limited.

The sub-assembly of the invention is applicable to any normally open clutch mechanism.

The invention allows to integrate, in a hybrid transmission system, the combination of a cut-off clutch mechanism KO and a double clutch, at least one of the mechanisms of which is provided with the sub-assembly of the invention.

BRIEF DESCRIPTION OF THE FIGURES Other characteristics and advantages of the invention will emerge on reading the description which follows, with reference to the appended and detailed figures below.

Figure IA is a sectional view of a hybrid transmission system comprising a cut-off clutch mechanism KO integrating, on the left side, the subassembly of the invention in the disengaged (upper part) and engaged (lower part) positions and, on the right side, a double-clutch mechanism that can also integrate the sub-assembly of the invention.

FIG. 1B is an axial half-section view of a double-clutch mechanism for a robotic gearbox incorporating the subassembly of the invention.

Figure 2 shows schematic views of a diaphragm extracted from the subassembly of the invention in various positions.

FIGS. 3A and 3B are front views of two embodiments of the diaphragm extracted from the subassembly of the invention.

FIGS. 4A and 4B are views, respectively, of the front and in exploded perspective of the sub-assembly of the invention produced by assembling the cover and the diaphragm of FIGS. 3A or 3B.

FIGS. 5A and 5B are detailed views of a first variant of the subassembly of the invention, respectively, at the start and at the end of the assembly of the diaphragm in the cover.

FIGS. 6A and 6B are detailed views of a second variant of the subassembly of the invention, respectively, at the start and at the end of the assembly of the diaphragm in the cover.

FIGS. 7A and 7B are detailed views of a third variant of the subassembly of the invention, respectively, at the start and at the end of the assembly of the diaphragm in the cover.

For the sake of clarity, identical or similar elements are identified by identical reference signs in all of the figures.

DETAILED DESCRIPTION OF EMBODIMENTS Naturally, the embodiments illustrated by the figures presented above are given only by way of nonlimiting examples. It is explicitly provided that one can combine these different modes and variants to propose others.

FIG. IA shows a hybrid transmission system comprising an electric motor 7 connected to a reaction plate 6, a cut-off clutch mechanism KO fixed to the reaction plate 6, a clutch friction disc 5 and a double-clutch mechanism K2 fixed to the reaction plate 6.

FIG. IB represents a double-clutch mechanism able to be integrated in a hybrid transmission system in which a heat engine is associated with an electric motor (as illustrated by the embodiment of FIG. IA) and / or in a robotic gearbox transmission system.

A traditional embodiment of these double clutch mechanisms is described and shown, in particular, in WO 2015/180778.

Such a double-clutch mechanism comprises a first mechanism and a second clutch mechanism allowing the passage of ratios of different parities.

The improvement brought by the invention to these double clutch mechanisms consists in eliminating the elastic preloading washer, as illustrated by FIGS. IA, IB.

Such a double-clutch mechanism, such as the K2 mechanism (Figure IA), is normally open. The mechanism K2 is engaged, in particular, with two transmission shafts A1, A2 which are generally coaxial (shown diagrammatically in FIG. IA), connected to the robotic gearbox (not shown).

In the embodiment of hybrid transmission of Figure IA, the electric motor 7 is associated with the internal combustion engine embodied here by a crankshaft 8.1 and a driving shaft 8.2. The electric motor 7 includes a stator

7.1 coupled to a rotor 7.2 secured to the reaction plate 6. The friction disc 5 carries friction linings 5.1. The reaction plate 6 is supported on the driving shaft 8.2 via the bearing 6.1.

The friction disc 5 transmits the torque from the heat engine when the KO cut-off clutch mechanism is closed.

When only the electric motor 7 is running, the cut-off clutch mechanism KO is open (disengaged position, upper half-view in FIG. IA). This situation generally corresponds to low vehicle speeds (for example starting).

From a predetermined speed threshold or when the charge level of the batteries supplying the electric motor 7 is low, the cut-out clutch mechanism KO closes automatically (engaged position, lower half of FIG. IA) under the action of a control stop 9 (mechanical or hydraulic). Closing the KO cut-off clutch mechanism triggers the internal combustion engine. The robotic gearbox then receives, jointly, the torque from the internal combustion engine and that produced by the electric motor 7. The double-clutch mechanism then makes it possible to distribute the overall torque over one of the two transmission shafts ( A1 or A2).

In FIG. 1A, the cut-off clutch mechanism KO comprises a diaphragm 1.1 housed in a cover 2.2 fixed on the reaction plate 6. The cut-off clutch mechanism KO is normally open.

In Figure IB, the double-clutch mechanism comprises a first diaphragm 1.1 housed between an outer cover 2.1 and an inner cover 2.2 containing a second diaphragm 1.2. The outer cover 2.1 and the inner cover 2.2 are axially offset.

The diaphragms 1.1 and 1.2 are cylindrical components, the central part of which is provided with a central orifice 1.20 and a series of radial fingers 1.22, more particularly visible in FIGS. 4A and 4B, on which a control stop 9 (hydraulic or mechanical) is supported.

The central part is extended radially outwards by an intermediate annular part 1.23 with a so-called "belleville" profile.

The covers 2.1, 2.2 have a generally hollow shape and include an annular bottom 2a extending in a plane perpendicular to the axis of revolution X of the double clutch and an outer side wall 2b of substantially cylindrical shape extending the bottom 2a from its outer periphery.

In section in a plane passing through the axis X, the bottom 2a and the side wall 2b of the diaphragm form between them an angle between 30 ° and 90 °.

The first diaphragm 1.1 is supported both on a first projection

3.1 carried by the inner face of the bottom 2a of the outer cover 2.1 and on a second projection 3.2 carried by the outer face of the inner cover 2.2 (visible in FIG. 1B alone).

As illustrated more particularly by FIG. 1B, the second clutch mechanism comprises a second pressure plate 4 and a reaction plate 6 ’between which extends a friction disc 5.

According to a variant of the invention, it is possible to combine the embodiments of Figures IA and IB so that the hybrid transmission system incorporates a cut-off clutch mechanism KO, as illustrated by the Figure IA, as well as a double-clutch mechanism K2, as illustrated in Figure IB. For this purpose, the reaction plate 6 ′ of the double-clutch mechanism (FIG. 1B) is made to rotate with the reaction plate 6 connected to the electric motor 7 (FIG. IA).

The connection of the two reaction plates 6, 6 'is ensured, for example, by means of screws or splines (not shown). The reaction plate 6 ′ then receives the torque from the reaction plate 6 which is generated by the electric motor 7.

In general, the second diaphragm 1.2 must be mounted, like the first diaphragm, between two support zones. Its first support zone here consists of a projection 3.3 formed on the inner face of the inner cover

2.2 and the second support area is formed on a cord 4.1 carried by the pressure plate 4 while the third support area, which was previously located on the preloading washer, is now and according to the invention, deleted.

With the exception of the inner cover 2.2 and the second diaphragm 1.2 integrated into the second clutch mechanism, the other components of the double-clutch mechanism (including the first diaphragm 1.1 and the outer cover 2.1) are not modified. and conform to the description and Figure 2 of WO 2015/180778.

Thus, according to the invention and as illustrated, in particular, by the views, respectively, in section and from the front of Figures IA, IB and 4A, the inner cover 2.2 and the second diaphragm 1.2 composing the second clutch mechanism are, in turn, modified so that the third support area of the second diaphragm 1.2 is now located on the inner cover itself while ensuring, after mounting in the cover 2.2, a force preload of the diaphragm 1.2. This effort constraint is between 100 and 400 N More specifically, the diaphragm 1.2 carries, on its outer peripheral edge, at least two support legs 1.21 and, preferably, six legs distributed circumferentially around the X axis and which extend radially in the plane of the annular part. The free ends of the legs 1.21 are intended to be engaged, under stresses of effort, in openings 2.21 forming a counter-support which are formed in the side wall 2b of the cover 2.2, as illustrated in FIG. 2.

Figure 2 schematically illustrates the kinematics of the second diaphragm 1.2 and its cooperation with the cover 2.2 according to the improvement of the invention.

In the free state of the diaphragm 1.2, as illustrated by position 1 in the upper part of FIG. 2, the support legs 1.21 are flat and oriented at an angle oc of between 0 ° and 15 ° relative to the plan of the belleville section 1.23. This configuration corresponds more particularly to the diaphragm according to the embodiment of FIG. 3B.

However, according to variants not shown, the support legs could have a curvilinear profile.

In the storage position illustrated by position 2 of Figure 2, the diaphragm 1.2 is placed inside the cover 2.2 and the support tabs 1.21 are then introduced into the openings 2.21. In this position, the belleville part 1.23 of the diaphragm 1.2 is in contact with the projection 3.3 of the cover 2.2. The diaphragm is then subjected to a prestressing force which causes the belleville part 1.23 to pivot (materialized by the arrow in FIG. 2) around an axis passing through the projection 3.3 of the cover 2.2. The purpose of this prestressing is to immobilize the diaphragm in the cover before subsequent assembly of the sub-assembly in a transmission system, for example, of the hybrid type.

Still in this position and under the effect of the force constraint, the legs 1.21 come to bear on the abutment face 2.31 of the openings 2.21 by tilting at an angle β in the opposite direction to the initial angle oc around a circumferential inflection line 1.2a located at their junction with the belleville part 1.23.

After mounting the sub-assembly in a transmission system, the belleville part 1.23 of the diaphragm 1.2 is in contact, on the one hand, with the projection 3.3 of the cover 2.2 and, on the other hand, with the cord 4.1 of the pressure plate 4. During the declutching phase, the fingers 1.22 are actuated by the control stop 9 and the diaphragm 1.2 reaches an intermediate position called “kissing point” or “licking point” illustrated by position 3 of the Figure 2 (corresponding to the contacting of the pressure plate 4 with the linings of the friction disc 5).

In this position 3, the legs 1.21 relax to return to their original shape while remaining in abutment on the abutment faces 2.31. The prestressing force maintains contact between the diaphragm 1.2 and the projection 3.3 of the cover

2.2 and thus avoid micro-movements as well as wear phenomena caused by possible friction at the interface between the diaphragm 1.2, the cover 2.2 and pressure plate 4.

Between the “kissing point” position and the fully engaged position illustrated by position 4 in the lower part of FIG. 2, the pressure plate 4 still moves axially to compress the progressive system of the friction disc 5 (visible in Figure IB). The support of the diaphragm 1.2 is then distributed between the cord 4.1 of the pressure plate 4 and the projection 3.3 of the cover 2. In this position, the legs 1.21 can no longer be in contact with the abutment faces of the openings 2.21, like this is illustrated in Figure 2.

Thus, whatever the position, the diaphragm 1.2 remains in permanent contact with the projection 3.3 of the cover 2.2.

In the embodiment of Figure 3A, the periphery of the diaphragm

1.2 is here provided with petals 1.24 of which at least some bear the legs 1.21. Centering of the diaphragm 1.2 is carried out, in a conventional manner, by means of rivets mounted between the petals 1.24.

Preferably, the legs 1.21 have a tapered profile whose end is rounded, as illustrated in FIGS. 3A, 3B. This profile is adapted to the geometry of the openings 2.21 taking here, in the embodiments shown, the form of slots, to reduce the contact pressures and thus limit wear.

The slots 2.21 of the slots 2.21 of the cover 2.2 have a bayonet profile consisting of an open notch 2.21a extended laterally by a blind hole 2.21b. The notch 2.21a opens, on the one hand, to the outside on the edge of the cover 2.2 and, on the other hand, into the blind hole 2.21b, as illustrated in FIGS. 5B, 6B and 7B.

The notch 2.21a allows the introduction of the end of the legs 1.21 into the slot 2.21 while the orifice 2.21b ensures, after rotation of a few degrees of the diaphragm 1.2, the setting under force constraints of the legs 1.21 between two faces 2.31, 2.32 one of which 2.31 forms a stop for the storage position and the disengaged position of the diaphragm 1.2.

The wedge orifice 2.21b extends perpendicular to the open notch 2.21a and one of its lateral faces is bevelled to facilitate the introduction and the subsequent movement of the legs 1.21 between the disengaged and engaged positions of the diaphragm 1.2.

The wedge orifice 2.21b is delimited and closed towards the outside, by a circumferential wall 2.3, the face 2.31 of which faces towards the inside of the slot 2.21 forms the stop in the disengaged position of the diaphragm 1.2.

In the variant illustrated in Figures 5A and 5B, the circumferential wall

2.3 is made directly and in one piece with the side wall 2b of the diaphragm 2.2. In this case, the mounting of the diaphragm 1.2 is carried out by positioning the legs 1.21 in line with the notches 2.21a then by moving the diaphragm axially to engage the legs in the slots 2.21, as illustrated by FIG. 5A, until they are brought to the interior beyond the plane of the circumferential wall 2.3.

The next step is to turn the diaphragm 1.2 by an angle between 5 ° and 20 ° while applying a slight compression to pass the legs behind the wall 2.3 inside the hole 2.21b in contact with the inner face 2.31 which has the effect of putting the diaphragm slightly under load.

The legs 1.21 are then enclosed in the slots 2.21 being able to move in the blind hole 2.21b between the two faces 2.31 and 2.32 when the diaphragm 1.2 passes from the disengaged position to the engaged position.

However, it is not intended that the legs 1.21 come into contact with the face 2.32 even in the engaged position.

In the variant illustrated in Figures 6A and 6B, the circumferential wall

2.3 is produced by deformation of a side 2.30 which projects axially towards the outside of the cover 2.2 before mounting the diaphragm 1.2, as illustrated in FIG. 6A.

In this case, the mounting of the diaphragm 1.2 is carried out by positioning the tabs 1.21 in line with the slots 2.21 and then moving the diaphragm axially to engage the tabs in the orifice 2.21b, as illustrated in FIG. 6A, up to to bring them inside the slots beyond the edge of the cover.

The next step then consists in folding down the side 2.30 by means of a tool such as a press P to place it in the circumferential extension of the rim of the cover, as illustrated in FIG. 6B. The advantage of this variant lies in the fact that it is not necessary to rotate the diaphragm when assembling the sub-assembly.

As in the variant of FIGS. 5A, 5B, the legs 1.21 are then enclosed in the slots 2.21 while being capable of moving in the blind hole 2.21b between the two faces 2.31 and 2.32 when the diaphragm 1.2 passes from the disengaged position to the engaged position. The face 2.31 serves as a counter-support when the diaphragm is in the disengaged position.

In the variant illustrated in Figures 7A and 7B, the circumferential wall

2.3 is produced in the form of a blade 2.33 which is brought in by translation and then fixed on the circumferential rim of the cover 2.2 after introduction of the tabs 1.21 in the slots 2.21, as illustrated by the arrows in FIG. 7B. Once the blade 2.33 is fixed on the edge of the cover 2.2, its inner face forms the abutment face 2.31 against the support of the legs 1.21.

As a variant, the blade 2.33 can completely cover the orifice 2.21b and the notch 2.21a.

According to this variant, it is also possible to provide a draft 2C produced on the edge of the cover 2.2 and intended to receive the blade 2.33 without creating any additional thickness.

As in the variants of FIGS. 5A, 5B and 6A, 6B, the tabs 1.21 are then enclosed in the slots 2.21 while being capable of moving in the blind hole 2.21b between the two faces 2.31 and 2.32 when the diaphragm 1.2 goes from the disengaged position to the engaged position. The face 2.31 also serves here as a counter-support when the diaphragm is in the disengaged position.

The sub-assembly of the invention is applicable to any normally open clutch mechanism and can advantageously be integrated into a hybrid transmission system, by equipping the KO cut-off mechanism and / or the double-clutch mechanism.

Claims (11)

claims 1. A normally open clutch mechanism sub-assembly, comprising a diaphragm (1.2) housed in a cover (2.2) having a side wall (2b) and a bottom (2a) the inner face of which carries a projection (3.3) on which said diaphragm comes to bear, characterized in that said diaphragm (1.2) carries, on its outer peripheral edge, at least two tabs (1.21) which extend radially and whose free ends are engaged, under stresses of force, in openings (2.21) forming counter-supports which are formed in the side wall (2b) of said cover. 2. Sub-assembly according to claim 1, characterized in that said openings (2.21) are each formed by an orifice (2.21b) into which opens the end of the support tabs (1.21) of the diaphragm (1.2), said orifice ensuring wedging under stress constraints of said tabs between two faces, one of which forms a stop for the disengaged position of the diaphragm. 3. Sub-assembly according to claim 1 or 2, characterized in that said openings (2.21) of the cover (2.2) have a bayonet profile consisting of an open notch (2.21a) allowing the introduction of the end of the support legs (1.21) and opening laterally into an orifice (2.21b) ensuring wedging under force stresses of said legs between two faces (2.31, 2.32), one of which forms a stop for the disengaged position of the diaphragm (1.2 ). 4. Sub-assembly according to the preceding claim, characterized in that said wedging orifice (2.21b) extends perpendicular to said open notch (2.21a). 5. Subassembly according to one of the preceding claims, characterized in that said openings (2.21) are delimited by a circumferential wall (2.3) whose inner face (2.31) forms the stop of the support legs (1.21) of the diaphragm (1.2) in the disengaged position. 6. Subassembly according to the preceding claim, characterized in that said circumferential wall (2.3) consists of a blade (2.33) attached and fixed to the edge of the side wall (2b) of the cover (2.21). 7. Sub-assembly according to claim 5, characterized in that said circumferential wall (2.3) is produced by deformation of a sidewall (2.30) carried by the rim of the side wall (2b) of the cover (2.2). 8. Normally open clutch mechanism, characterized in that it comprises a sub-assembly according to one of the preceding claims and a pressure plate (4) carrying a support bead (4.1) bearing on the diaphragm (1-2). 9. Normally open clutch mechanism according to the preceding claim, characterized in that the diaphragm (1.2) comprises an annular part (1.23) disposed, at least partially, between a projection (3.3) of the cover (2.2) and the cord d 'support (4.1) of the pressure plate (4) and from which said support legs (1.21) extend radially beyond said projection (3.3). 10. Double-clutch mechanism comprising a first diaphragm (1.1) housed between an outer cover (2.1) and an inner cover (2.2) containing a second diaphragm (1.2), the two covers being axially offset, characterized in that the cover interior (2.2) and the second diaphragm (1.2) consist of a sub-assembly according to one of claims 1 to 7. 11. Hybrid transmission system comprising a normally open clutch mechanism according to one of claims 8 or 9, an electric motor (7) and a double-clutch mechanism according to claim 10.