Clutch bearing, a clutch drive device, and a motor vehicle equipped with such a bearing and with such a device

This bearing forms a clutching-declutching thrust bearing for a motor vehicle and comprises an inner ring, an outer ring and rolling elements. A flange mounted on the inner ring is equipped with two crenellated series of flange segments extending radially on the same side of a cylindrical web of the flange, and being offset angularly about an axis of symmetry of the inner ring, and axially along said axis. In addition to the bearing, the device further includes a control device, provided with a stationary portion and with a moving portion mounted to move axially and suitable for moving the bearing relative to the clutch mechanism, and a protective bellows disposed between the stationary portion and the bearing. The flange segments define between them an annular volume for receiving and for clamping one edge of the bellows.

BACKGROUND OF THE INVENTION

The present invention relates to a bearing forming a thrust bearing for a clutch for a motor vehicle. The invention also relates to a clutch device including a bearing of the above-mentioned type. Finally, the invention relates to a motor vehicle equipped with such a bearing or with such a clutch device.

In the automotive industry, it is known to use a bearing comprising an inner ring, an outer ring, and rolling elements for constituting a clutching-declutching thrust bearing making it possible to control a diaphragm spring that is part of a declutching mechanism that is known per se. Such a bearing can be incorporated into a clutch drive device as is known, for example, from FR-A-2 740 193. In that device, a bellows is used for isolating from the outside the portions that move relative to one another from the outside, in particular a control piston for causing the inner ring of the bearing to move axially, and a pre-stressing spring for pre-stressing the bearing. In order to perform its function effectively, that bellows must be prevented from moving relative to one of the rings of the bearing, namely, in the example given in that document, the inner ring which is prevented from moving in rotation about its axis of symmetry. One end of the bellows is clamped by a band held in an annular groove provided in the outside diameter of a link part made of a molded synthetic material. The band is also made of a synthetic material and the use of two parts makes the function of fastening the end of the bellows both complex and costly. In addition, putting the band into place in the groove in the link part requires a specific assembly step, which increases the cost of the above-mentioned function and requires qualified labor.

In addition, it is known from JP-A-2002 340026 that a bearing can be equipped with a flange that is provided firstly with locking tongues designed to co-operate with a piston and, secondly with abutments for stopping a bellows heel in a single direction. The bellows is not held stationary on the flange, thereby presenting a risk of accidental disassembly. The bellows is therefore not durably in place.

SUMMARY OF THE INVENTION

An object of the invention is to remedy those drawbacks more particularly by proposing a novel bearing forming a clutching-declutching thrust bearing, with which it is easier and less costly to put one edge of a protective bellows into place.

To this end, the invention provides a bearing forming a clutching-declutching thrust bearing for a motor vehicle, said bearing comprising an inner ring, an outer ring and rolling elements disposed between the inner and outer rings. This bearing is characterized in that a flange mounted on the inner ring is equipped with two crenellated series of flange segments extending radially on the same side of a cylindrical web of the flange, said flange segments being offset angularly about an axis of symmetry of the inner ring, and axially along said axis.

By means of the invention, the two series of flange segments, which are offset both angularly and axially, define between them an annular volume making it possible to receive and to clamp the edge of a protective bellows belonging to a clutch drive device. The two series of flange segments can be made in a metal part which is less voluminous than a part made of a molded synthetic material, and which has resilience that can be used for imparting to the flange segments a function of clamping the edge of a bellows between them.

In advantageous but non-essential aspects of the invention, such a bearing may incorporate one or more of the following characteristics, taken in any technically feasible combination:the two series of flange segments extend radially outwards relative to the cylindrical web segment;the two series of flange segments define between them a volume suitable for receiving one edge of a bellows;the flange is made of metal, and the series of flange segments are obtained by localized cutting out and folding of a radially outer portion of the flange;the flange segments of a first series of flange segments extend radially in prolongation of an annular portion of the flange that is perpendicular to an axis of symmetry of the flange, while the flange segments of the second series of flange segments are parallel to the flange segments of the first series and are obtained by folding certain angular zones of the radially outer portion of the flange at 90°, in two opposite directions;the flange is provided with a punched out portion that projects radially, towards the axis of symmetry of the inner ring, from a cylindrical portion of the flange centered on said axis. This punched out portion may serve to receive the end of an end turn of a spring;the flange is mounted on the inner ring by being held stationary thereon both in rotation and in axial translation, relative to the axis of symmetry of the inner ring;there are six flange segments in the first series, and each of them extends over a sector of an angle of about 30° about the axis symmetry of the flange and there are six flange segments in the second series, and each of them extends over a sector of an angle of about 30° about the axis of symmetry; andthe flange includes a second annular portion parallel to the annular portion from which the flange segments of the first series extend radially in prolongation, said second annular portion forming a surface suitable for receiving the end turn of a spring bearing thereagainst.

The invention also provides a clutch drive device comprising: a bearing as mentioned above, said bearing being capable of acting on a diaphragm spring of a clutch mechanism; a control device provided with a stationary portion and with a moving portion mounted to move axially relative to the stationary portion and suitable for moving the bearing relative to the clutch mechanism; and a protective bellows disposed between the stationary portion and the bearing. This device is characterized in that the two series of flange segments define between them an annular volume for receiving and for clamping one edge of the bellows.

Advantageously, the flange forms a bearing zone for a spring exerting an axial force on the inner ring. In which case, the flange is provided, in the bearing zone for the spring, with a piece in relief for locking the spring and the flange in rotation. It is possible to make provision for said piece in relief to be formed by a punched-out portion in the flange.

In another advantageous aspect of the invention, a control member for controlling the axial position of the bearing is mounted in self-centering manner relative to the inner ring.

Finally, the invention provides a motor vehicle equipped with a bearing or with a drive device as mentioned above.

Such a vehicle is cheaper to manufacture and easier to maintain than prior art vehicles, in particular when work is to be done on the clutch bearing, by disuniting the clutch bearing from a protective bellows and by re-uniting said bearing with said bellows.

DETAILED DESCRIPTION OF THE INVENTION

The device1shown inFIG. 1includes a hydraulic control subassembly that includes a stationary support2, in general mounted on the casing of a gearbox (not shown). The control subassembly also includes a piston3received entirely inside an annular chamber4provided in the support1and designed to receive a control hydraulic fluid fed in via a fitting5. The piston3is equipped with two sealing gaskets6and7in contact respectively with the radially inner wall8and with the radially outer wall9of the chamber4.

The device1also includes a bearing20forming a clutching-declutching thrust bearing having its inner ring referenced22and its outer ring referenced24. A series of balls26are held in position, in the volume defined between the rings22and24, by means of a cage28.

The axes of symmetry of the rings22and24are referenced respectively X22and X24, these axes coinciding with each other when the bearing20is in the assembled configuration.

The bearing20also includes a gasket30that extends radially relative to the axes X22and X24between the rings22and24, this gasket comprising a metal reinforcement32and an elastomer body34, and being anchored to the ring24and provided with a lip36that bears slidably against the ring22.

A metal sleeve40is mounted on the ring22and it is designed to be fastened to a thrust element50whose axial position, along an axis X2defined by the support2and coinciding with the axes X22and X24when the device1is in the assembled configuration, is controlled by the piston3.

The sleeve40is mounted in such a way as to allow for its radial displacement relative to the ring22. More precisely, the sleeve40is provided with tabs41that define an outer zone42for receiving the radially inner edge221of the ring22, with radial clearance, so that the edge221can slide radially in the zone42. This allows the relative positions of the parts22and40to be adjusted perpendicularly to the axis X22. This makes it possible to accommodate misalignment of the axis X22and of the central axis X40of the sleeve40when these axes are parallel but do not coincide.

A conical ring44disposed between the tabs41and the edge221performs the function of contributing to guaranteeing a continuous axial preload between the ring22and the sleeve40, even during any relative radial self-centering movements therebetween. By means of the radial clearance between the edge221and the zone42, the sleeve40is mounted in self-centering manner on the ring42.

In addition, the sleeve40is provided with punched out portions46enabling it to be fasten in an external peripheral groove52in the thrust element50, thereby guaranteeing that a thrust force is transmitted effectively between the piston3and the sleeve40. The geometrical shape of the sleeve40at the zone42makes it possible to transmit the thrust force to the edge221, this force being transmitted, between the ring22and the ring24, via the balls26.

In practice, the ring22is prevented from rotating about the axis X22, whereas the ring24rotates about the axis X24, at a speed that depends, in particular, on the engine speed.

The ring24is in abutment against a diaphragm spring60that is shown in part in chain-dotted lines that show its tips and that is part of a declutching mechanism, that is known per se and that is not described in any further detail.

A spring70is installed between the support2and the ring22and exerts thereon a resilient preloading force, directed towards the diaphragm spring60. On the same side as the support2, the spring70bears against a metal washer72that is secured to or integral with the support2.

A bellows80is mounted around the elements4,6,50, and70in order to isolate them from the outside. One edge81of the bellows80is clamped by the washer72against the support2.

A flange or thrust ring100is mounted in tight-fitting manner on the ring22, and it enables the edge82of the bellows that is further from the washer72to be received.

The flange100is made of steel, by die stamping and cutting out. The flange100includes a cylindrical web102centered on an axis X100that coincides with the axis X22in the configuration in which the flange100is mounted on the ring22. The flange100includes a second cylindrical web104that is also centered on the axis X100and that is connected to the web102via an annular portion106that is perpendicular to the axis X100. The webs102and104are circular in section.

The web102and the portion106are dimensioned so as to enable the flange100to be locked resiliently by friction inside the radially outer edge222of the ring22, so that, once in place on this edge, the flange100is secured to the ring22so that is constrained both to move in rotation therewith about the axis X22and to move in translation therewith parallel to said axis.

The flange100also has an annular portion108that is parallel to the portion106and thus perpendicular to the axis X100. This portion108extends the web104at the end thereof that is opposite from the portion106.

Starting from the portion108, a first crenellated series S1of flange segments110extend radially relative to the axis X100towards the outside starting from the portion108. As can be seen inFIG. 3, there are six flange segments and, each of them extends over a sector of an angle α110of about 30° about the axis X100.

The radially inner edge of the flange100is referenced112, and its radially outer edge is referenced114.

Between two adjacent flange segments110, the portion108is folded over at about 90° towards the radially outer surface104A of the web104so as to form a cylindrical web segment116parallel to the web104. Opposite from the portion108, each web segment116is folded over in the opposite direction relative to the fold formed between the portions108and116, so that six other flange segments118are formed that belong to a second crenellated series S2of flange segments, each of these flange segments extending about the axis X100over a sector of an angle β118of about 30°, and each of said flange segments extending radially outwards relative to the segment116of which it constitutes the end, and being parallel to the adjacent flange segments110.

Thus the two series S1and S2of crenellated flange segments110and118extend radially, relative to the axes X22and X100that coincide when the bearing is in the assembled configuration, on the same side of each cylindrical web segment116, namely outwards relative thereto. If an imaginary cylindrical surface S116of a cylinder having a circular base, which surface contains the radially outer surfaces of the web segments116, is considered, then the series S1and S2of crenellated flange segments110and118extend radially outwards relative to the surface S116, at either axial end thereof.

The edge114is formed by associating the free edges110A of the flange segments110with the free edges118A of the flange segments118. The series S1and S2of the crenellated flanges segments110and118are thus formed at the edge114.

The portion of the flange100that is situated radially outside the web104is referenced109. This portion109comprises the portions108,110,116, and118. The crenellated flange segments110and118are formed by localized cutting out and folding of the portion109.

The flange segments110and118belong to respective ones of the two crenellated series S1and S2by being offset angularly relative to one another about the axis X100and the axis X22in the configuration in which the flange100is mounted on the ring22. In addition, the flange segments110and118are offset axially by a distance d100along the axes X100and X22, due to the axial length of the segments116.

The two series of flange segments110and118define between them an annular volume V100for receiving the edge82of the bellows80. The volume V100is situated radially outside the segments of cylindrical web116parallel to the web104and outside the surface S116. The axial distance d100between two adjacent flange segments110and118, i.e. the axial width of the volume V100, is chosen to be slightly less than the axial thickness e82of the edge82, so that, once received in the volume V100, the edge82is resiliently clamped between said flange segments. Thus, it is not necessary to use an auxiliary part for holding the edge82of the bellows80stationary on the flange100.

At the portion106, the flange100forms a bearing surface for the end turn74of the spring70, on the same side as the bearing20. In other words the resilient force exerted by the spring70, is applied to the portion106of the flange100and, through it, to the edge222of the ring22.

A punched-out portion120is formed in the flange100, more precisely by pushing back a small portion of the web104towards the axis X100. This punched-out portion120receives the free end of the end turn74of the spring70bearing thereagainst, which makes it possible to prevent the flange100from moving in rotation relative to the spring70. In view of the possible friction inside the bearing20, it cannot be ruled out that the ring22might be driven in rotation due to the rotation of the ring24. Regardless of the direction in which the ring22rotates, the punched-out portion120then ends up coming to bear against the end of the turn74, thereby stopping the rotation of the flange100and, since said flange is mounted in tight-fitting manner on the ring22, preventing the ring22from rotating.

In aspects of the invention that are not shown, the flange can be prevented from rotating on the ring22by means of co-operating shapes, e.g. by being equipped with thin grooves co-operating with ribs provided in the inside surface of the ring22.

In addition, the number of crenellated flange segments and the sector angle through which each of the flange segments extends could be greater than or less than the values indicated for the embodiment described above.

The invention is shown with a clutch control device having a hydraulic control subassembly. However, it is applicable to a control device controlled by a fork or by any other equivalent mechanism.

A motor vehicle equipped with a bearing, such as the bearing20, or with a device, such as the device1, is cheaper to manufacture than prior art vehicles, given how easy it is put the bellows80into place, and it is easier to maintain, for the same reason.