Engagement-disengagement, suspension or steering release bearing, and motor vehicle equipped with such a release bearing

An engagement-disengagement, suspension or steering release bearing. The release bearing includes a rolling bearing forming a member for transmitting an axial force and comprising a rotating ring and a non-rotating ring between which a rolling chamber is mounted for rolling bodies and a sealing gasket, which is mounted on a first ring among the rotating and non-rotating rings, and which comprises a framework, having an edge folded down radially toward a groove arranged on a surface of the first ring, and a fitting, having a sealing lip in sliding bearing against, or adjacent to, a corresponding surface of the second ring, The fitting of the seal is suitable for filling the groove of the first ring and part of the fitting is jammed between the folded down edge of the framework and the groove in the configuration with the seal mounted on the first ring.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Non-Provisional Patent Application, filed under the Paris Convention, claiming the benefit of French Patent (FR) Application Number 1456877, filed on 17 Jul. 2014, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The invention relates to an engagement-disengagement, suspension or steering release bearing used in a motor vehicle to transmit an axial force between a non-rotating part, such as an actuating piston, and a rotating part, such as the noses of a transmission diaphragm.

BACKGROUND ART

In the automobile industry, it is known to use an engagement-disengagement release bearing to actuate the rotating diaphragm of a transmission from a translatable piston. To that end, the release bearing comprises a rolling bearing with rolling bodies, with a rotating ring designed to be in contact with the noses of the diaphragm, and a non-rotating ring that defines a central opening in which a maneuvering member is engaged secured to the piston or made up by a part thereof.

When such a release bearing is formed, it is essential for it not to be easy to disassemble, inasmuch as it is not always mounted in a corresponding housing or on a corresponding shaft as of its manufacture. Under these conditions, the inner and outer rings of such a release bearing may be subject to a separating force that is at least partially parallel to the rotation axis of the rolling bearing. When they are subjected to such a force, even with a relatively low intensity, the rings of the known release bearings tend to move axially away from one another. This may lead to the opening of the rolling chamber in which the rolling bodies are normally housed, and the loss of at least some of them.

Similar problems arise with the suspension release bearings and steering release bearings used in motor vehicles.

To offset these drawbacks, it is known to use an axial retaining seal, which is mounted between the two rings of the release bearing and which retains the outer ring or the inner ring when a separating force is applied on the release bearing. This seal further makes it possible to keep the grease near the rolling elements during operation and prevent the infiltration of outside particles in the rolling chamber.

Seals exist comprising a framework, which is crimped around the outer ring of the rolling bearing and which, as a result, forms an effective release bearing with respect to a pulling out force exerted on the rings. However, this type of seal increases the outer diameter of the rolling bearing, which is why seals anchored in the bore of the outer ring were developed.

In particular, FR-A-2,984,435 discloses a seal of this type, which is assembled within an engagement release bearing. This seal includes a rigid framework and a flexible fitting. The rigid framework comprises an edge, which is folded down radially toward a groove delimited on an inner radial surface of the outer ring. When the rings of the rolling bearing are subjected to a separating force, which is at least partially parallel to the axis of rotation of the rolling bearing, the rolling elements exert a reaction force on the seal and the framework of the latter deforms. The folded edge of the framework then becomes housed in the groove of the outer ring and forms a release bearing with respect to the reaction force, or pulling out force, exerted by the rolling bodies of the rolling bearing. However, the strength of this assembly is insufficient in case of significant separating force.

BRIEF SUMMARY OF THE PRESENT INVENTION

The invention more particularly aims to resolve these problems by proposing a new engagement-disengagement, suspension or steering release bearing having a greater resistance to a separating force of the rolling bearing rings, while remaining compact.

To that end, the invention relates to an engagement-disengagement, suspension or steering release bearing, the release bearing comprising a rolling bearing forming a member transmitting an axial force and comprising a retaining ring and a non-rotating ring between which a rolling chamber is defined for rolling bodies, a sealing gasket, which is mounted on a first ring among the rotating and non-rotating rings, and which comprises a framework, having an edge folded down radially toward a groove arranged on a surface of the first ring, and a fitting, having a sealing lip in sliding bearing against, or adjacent to, a corresponding surface of the second ring. According to the invention, the fitting of the seal is suitable for filling the groove of the first ring and part of the fitting is jammed between the folded down edge of the framework and the groove in the configuration with the seal mounted on the first ring.

Owing to the invention, when a separating force, at least partially axial, is applied on the rings of the rolling bearing, the rolling bodies exert a reaction force to the separating force on the seal, which tends to push the folded down edge of the framework of the seal toward the groove arranged in the first ring. The part of the fitting comprised between the framework of the seal and the groove is therefore compressed on the one hand, and sheared on the other hand. In fact, the adherence force of the first ring on the fitting of the seal and the reaction force of the beads are two globally opposing forces, which share the part of the fitting filling the groove. This shearing of the material is even greater when the separating force applied is high. The separating force of the rings therefore results in the formation of a shear stress at the fitting. The latter being flexible, it withstands high shear stresses, which gives the release bearing a significant resistance to disassembly.

According to advantageous, but optional aspects of the invention, a rolling bearing may include one or more of the following features, considered in any technically allowable combination:The part of the fitting jammed between the folded down edge of the framework and the groove is provided to be sheared during the application of an axial separating force applied on the rings of the rolling bearing.The rolling bodies are suitable for exerting a reaction force to the axial separating force on the seal, which may push the folded down edge of the framework toward the groove and shear the fitting part jammed between the two.The groove is arranged on an inner radial surface of the outer ring.The outer diameter of the framework is smaller than the diameter of the inner radial surface of the outer ring.The difference in diameter between the outer diameter of the framework and the diameter of the inner radial surface of the outer ring is less than 0.8 mm, preferably equal to 0.3 mm.The framework is made from metal and the fitting is made from elastomer.The seal is secured in rotation with the outer ring, which rotates.The groove has a depth greater than 0.1 mm, preferably equal to 0.2 mm.

The invention also relates to a motor vehicle, comprising at least one release bearing as previously described.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

FIGS. 1 to 4show an engagement-disengagement release bearing1. This release bearing is designed to be mounted in a motor vehicle to transmit an axial force E1exerted by a piston, not shown, toward a rotating transmission diaphragm, a nose3of which is shown inFIG. 1. In the example ofFIG. 1, the diaphragm bears directly against the ring20on the left side ofFIG. 1, but a wearing ring may also be inserted between the noses3and the ring20.

The release bearing1comprises a rolling bearing2having a rotating outer ring20secured in rotation with the diaphragm and a non-rotating inner ring22between which a rolling chamber is defined. A single series of rolling bodies24is positioned in the rolling chamber, while being kept in position by a cage26. In the example of the figures, the rolling bodies24are beads, but they may be needles or rollers.

Reference X2denotes a central axis of the rolling bearing2, i.e., the relative axis of rotation of the rings20and22with respect to one another. The rings20and22are centered on the axis X2.

In the rest of the description, a rear direction designates an axial direction, i.e., parallel to the axis X2, that is turned toward the piston, the piston being suitable for bearing on the right side of the rolling bearing2inFIG. 1. Conversely, a front direction designates an axial direction, opposite the aforementioned direction, that is turned toward the diaphragm or toward a clutch pressure plate, not shown.

The rotating ring20comprises an annular part20bthat is positioned in front, i.e., on the side of the noses3, and that extends radially to the axis X2, and a tubular part20a, which is positioned behind, and which extends globally parallel to the axis X2. The noses3of the diaphragm bear against a front face S20bof the front part20bopposite the rolling chamber.

The inner ring22also comprises an annular part22b, which is positioned in front and which extends radially to the axis X2, and a tubular part22a, which extends backward globally parallel to the axis X2.

A sheet metal sleeve5, shown in mixed lines inFIG. 1, is designed to maneuver the noses3of the diaphragm, by transmitting the force E1from the piston to the rolling bearing4. This sleeve5comprises a cylindrical part50that is positioned behind the sleeve5, that is suitable for receiving the actuating piston of the clutch and is provided with several lances51, regularly distributed around a central axis of the sleeve5. The central axis of the sleeve5is in practice combined with the rolling axis X2. The lances51make it possible to attach the sleeve5on the piston. The sleeve5comprises a second cylindrical part54, which is positioned in front of the sleeve5, which is centered on the axis X2and which includes a free edge curved radially outwardly, such that the sleeve5is crimped around the free edge of the front part22bof the inner ring22. In this way, the sleeve5and the ring22of the rolling bearing2are axially secured. The sleeve5lastly comprises an annular connecting part52between the parts50and54, which is radial to the central axis of the sleeve, centrifugally, and which bears against a rear face of the front part22bof the inner ring22.

A lock washer7, also shown in mixed lines, is positioned coaxially around the cylindrical part54. More specifically, this lock washer7is inserted between the curved free edge of the part54and the front face of the part22bof the ring22.

References S20and S22respectively denote the rolling surfaces of the beads24on the ring20and on the ring22. These surfaces S20and S22are curved, in the form of a toroid portion, with a curve radius equal to that of the beads24. The rings20and22each extend toward the rear, relative to the surface S20or S22, by a tubular part centered on the axis X2. Thus, reference S20idenotes an inner radial surface of the part20a, that inner radial surface S20iextending the surface S20toward the rear. Reference S22ealso denotes an outer radial surface of the part22a, that outer radial surface S22eextending the surface S22toward the rear. Reference D20idenotes the diameter of the surface S20i; in the example, the diameter is chosen to be equal to 62.49 mm.

A peripheral groove21is arranged on the inner radial surface S20iof the ring20. This groove21extends over the entire circumference of the ring20and has a globally V-shaped section with a flat bottom. The groove21comprises a bottom21aand two side edges21b. The two edges21bare inclined relative to a direction radial to the axis X2such that the width of the groove21decreases going from the mouth to the bottom21aof the groove21. Reference12ldenotes the maximum width of the groove21, i.e., the width measured at the mouth of the groove. The groove21has a depth p21, measured radially relative to the axis X2, which is greater than 0.1 mm, preferably equal to 0.2 mm.

In one embodiment of the invention that is not shown, the peripheral groove21may assume the form of a series of grooves delimited over predetermined angular sectors.

A seal4is mounted coaxially between the rings20and22, behind the rolling bearing2. This seal4is fastened to the outer ring20and is designed to isolate the rolling chamber from the outside, opposite the noses3of the diaphragm. It further makes it possible to keep the grease near the rolling bodies during operation. The seal4is inserted between the surfaces S20iand S22e. It comprises a framework40made from a relatively rigid material, for example metal. It also comprises a fitting42made from a flexible material, which may be made from synthetic elastomer or natural rubber. The fitting42may be overmolded on the framework40or attached by any other appropriate means, such as gluing or welding. The fitting42forms a lip42awhich, in the example, bears slidingly against the outer radial surface S22eof the ring22. However, the lip42amay not be in contact with the surface S22e, but extend at a small radial distance therefrom, i.e., be adjacent to the surface S22e.

As more particularly shown inFIG. 3, the framework40comprises an annular part40athat is radial with respect to the axis X2, as well as a tubular skirt40bperpendicular to the part40a, which extends that part40atoward the front and which is centered on the axis X2. An outer edge40cof the skirt40is folded down radially toward the outside toward the ring20. That edge40cis continuous over the circumference of the framework40and is folded down radially toward the peripheral groove21. Reference D40cdenotes the outer diameter of the framework40, which corresponds to the outer diameter of the edge40c.

In one embodiment of the invention that is not shown, the edge40cmay be discontinuous.

As shown inFIG. 2, the outer diameter D40cof the framework40is slightly smaller than the diameter D20iof the inner radial surface S20iof the outer ring20. The folded down edge40cis therefore withdrawn relative to the bottom of the groove21. More specifically, the difference in diameter between the outer diameter D40cof the framework40and the diameter D20iof the inner radial surface S20iof the outer ring20is smaller than 0.8 mm, preferably equal to 0.3 mm.

Part42bof the fitting42fills the groove21. In fact, that part42bhas a radial thickness e42bthat is larger than or equal to the depth p21of the groove21and a width142bthat is greater than or equal to the maximum width12lof the groove21. In order to fill the groove21, the part42bmay therefore be shaped to the geometry thereof or compressed. That portion42bis jammed, due to the aforementioned difference in diameter, radially between the folded down edge40cof the framework40and the bottom21aof the groove21. In this way, the seal4is axially secured to the ring20.

When an axial separating force is exerted on the rings20and22, as shown by arrows F1and F2inFIG. 3, the ring20tends to slide to the left inFIG. 3, which separates the beads24from the surface S20, the beads tending to slide toward the surface S20irelative to the ring20. The beads24retain their axial position, along the axis X2, relative to the ring22because the surface S22has a sufficient concavity to keep the beads24in position.

Thus, the beginning of the relative axial movement between the rings20and22, in the direction of arrows F1and F2, results in bringing the beads24toward the part20a, then into contact with the seal4. In this configuration shown inFIG. 3, the beads24exert a force E2on the seal4normal to their surface. This force E2is a reaction force that results in pushing the folded down edge40cof the framework40toward the groove21. This causes the compression of the part42bof the fitting42inside the groove21on the one hand, and the shearing of that part42bon the other hand.

In fact, the ring20exerts, on the fitting42of the seal4, an adherence force, globally parallel to the axis X2and oriented forward, while the reaction force E2of the beads24, which is opposite the axial separating force F1, F2and which is transmitted to the part42bof the fitting42by the folded down edge40cof the framework40, exerts, on the part42b, a globally axial force oriented backward, i.e., opposite the adherence force between the fitting42and the ring20. These two opposing forces therefore shear the component material of the part42b.

The separating force of the rings20and22therefore results in the formation of a shear stress within the fitting42. The latter being flexible, it withstands high shear forces, which gives the release bearing1a high resistance to disassembly.

In so doing, the beads24improve the anchoring of the seal4relative to the ring20, which allows the seal4to withstand a reaction force, or separating force, exerted by the beads24.

In other words, the cooperation of the part42bof the fitting42with the groove21, under the action of the folded down edge40cof the framework40, results in the seal4forming an effective release bearing for a beginning of axial separating movement of the rings20and22, under the effect of the pulling out force represented by arrows F1and F2inFIG. 3.

It will be noted that the greater the pulling out force F1+F2is, the more the beads24push the folded down edge40ctoward the inside of the groove21owing to the force E2, and the more the part42bis compressed and sheared, which implies that the anchoring of the seal4on the ring20is that much more effective.

In the current case where the separating force of the rings20and22is essentially axial, the beads24act simultaneously over the entire circumference of the seal4. However, in the case where the separating force between the rings20and22is not strictly parallel to the axis X2, i.e., in the case where that force is only partially axial, the beginning of relative movement of the rings20and22may result in only part of the beads24coming into contact with the seal4. In that case, only one or several portions of the edge40ccompress(es) and/or shear(s) the part42bagainst the groove21. This is, however, sufficient to form a release bearing with respect to the separating or spacing movement of the rings20and22along the axis X2. It will be understood that, if the separating force is released, the ring20may return to the configuration ofFIGS. 1 and 2, in which the beads24are separated from the seal4.

The invention is described above and shown in the figures in the case where the seal4is mounted on the outer ring20. Alternatively, this seal4may be mounted on the inner ring22. In that case, the configuration of the seal is reversed and a groove similar to the groove21is arranged on the outer radial surface S22eof the inner ring22and the edge40cof the framework40is folded down radially toward the inside, toward the axis X2.

The invention is described above in the case where the outer ring is rotating. It may also be implemented in the case where it is the inner ring that rotates.

The invention can also be used with a rolling release bearing, as described in WO-A-2010/031756.

The invention is described above in the case of its use for an engagement-disengagement release bearing. It is also applicable to other release bearings, particularly a suspension release bearing or a steering release bearing.

The technical features of the embodiments and alternatives considered above may be combined with one another to create new embodiments.