FR2826416A1 - Friction clutch release bearing comprises two bushes and bearings, operating bush engaging interface part with force in bearing axial direction, bearing resiliently mounted with radial and axial play - Google Patents

Abstract

The release bearing comprises a bearing (21) having two bushes (22,23) and bearings (24). The operating bush engages with an interface part (31), activated by an operating part, with a force in the bearing axial direction. The force transmitted by the bearings and the other bush engages with clutch release means (7). The bearing is resiliently mounted relative to the interface part with radial and axial play. An elastic washer (36) is located axially between a transverse support face (38) of the operating bush and a transverse support face (37) connected to the interface part. The operating bush transverse support face engages with the washer in a support zone located radially at a distance from the washer centering diameter.

Description

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 The present invention relates generally to the control of a friction clutch and more specifically a clutch release bearing for such control.

 A friction clutch generally comprises a reaction plate, possibly in two parts to form a damping flywheel or a flexible flywheel, fixed in rotation on a first shaft, usually a driving shaft such as the crankshaft of the internal combustion engine. , and supporting by its external periphery a cover to which is attached at least one pressure plate.

 The pressure plate is integral in rotation with the cover and the reaction plate while being able to move axially under the stress of elastic engagement means with axial action controlled by declutching means; the engagement means may consist of helical springs, or one or two Belleville washers mounted in series or in parallel, subjected to the action of declutching levers forming the declutching means; generally, the engagement and disengagement means belong to the same part, for example a metal diaphragm bearing on the cover.

 A friction disc, carrying friction linings at its outer periphery, integral in rotation with a shaft, usually a driven shaft such as the input shaft of the gearbox, is interposed between the pressure plate and the reaction plate so as to be clamped together when the clutch is in the engagement position. The clutch means control the axial movement of the pressure plate when they are actuated by a declutching stop by means of the declutching means. The friction clutch is of the pulled type when the clutch release bearing, for disengaging the clutch, is itself "pulled" in the direction which brings the pressure plate closer to the cover; the friction clutch is of the pushed type when the clutch release bearing, for disengaging the clutch, is itself "pushed" in the direction which moves the pressure plate away from the cover.

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 A clutch release bearing usually comprises a bearing having one of the rings provided, when the clutch is of the pulled type, with means for coupling it to the declutching means, while the other ring is coupled to an interface member intended to be actuated by actuating means capable of exerting on this interface member a tensile force in the axial direction of the bearing.

 Ball bearings are often provided with so-called sealing means ensuring the protection of rolling elements, such as balls, and their raceways; these sealing means can be light, consisting of simple baffles, provide only partial protection, against dust for example, or more protection, against fluids, and consist of seals.

 Thus, in this context, the invention relates to a clutch release bearing intended to intervene in the actuation of a friction clutch, of the type comprising a bearing having two rings and rolling elements one of the so-called operating rings cooperating with an interface member intended to be actuated by operating means capable of exerting on this interface member a force in the axial direction of the bearing, which force is transmitted by the rolling elements to the other so-called cooperating actuating ring with the clutch disengaging means, said bearing being mounted resiliently with respect to the interface member with axial and radial play, said stop being of the self-centering type, an elastic washer being disposed axially between a transverse bearing face of the operating ring and a transverse bearing face linked to the interface member.

Such a stop is for example described in the French patent application filed on December 30, 1999 under the number 99 16 795, cited above.
In such a stop, the operating ring cooperates with the elastic washer in an area of the latter close to its outer periphery; such an arrangement presents the risk of seeing the elastic washer cone under load, which would lead to jamming thereof and / or to deterioration of the seal close to it.

 The object of the present invention is to avoid these drawbacks.

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 Thus, according to the invention, a declutching stop intended to intervene in the actuation of a friction clutch, of the type comprising a bearing having two rings and rolling elements, one of the so-called operating rings cooperating with a member. interface intended to be actuated by operating means capable of exerting on this interface member a force in the axial direction of the bearing, which force is transmitted by the rolling elements to the other so-called actuating ring cooperating with the clutch disengaging means, said bearing being mounted resiliently with respect to the interface member with axial and radial play, said stop being of the self-centering type, an elastic washer being disposed axially between a transverse bearing face of the operating ring and a transverse bearing face linked to the interface member, is characterized by the fact that the transverse bearing face of the operating ring coop era with the elastic washer according to a support zone located radially away from the diameter, outside or inside, of centering of the elastic washer.

 Advantageously, the transverse bearing face of the maneuvering ring is offset axially outwards relative to the seal disposed transversely, between the two rings of the bearing, on the side of said transverse bearing face; one is thus sure to avoid deterioration of said seal.

 Preferably, the transverse bearing face of the operating ring has a reduced radial dimension with respect to the smallest radial dimension of the operating ring.

 According to a first form of application to a stop intended to intervene in the actuation of a friction clutch of the pulled type, the maneuvering ring is the outer ring of the bearing.

 Preferably, the outside diameter of the elastic washer is greater than the outside diameter of the outer ring of the bearing.

 Advantageously, the elastic washer extends radially inside a groove provided at the internal periphery of a skirt presented by the interface member.

 According to another form of application to a stop intended to intervene in the actuation of a friction clutch of the pulled type, the operating ring is the internal ring of the bearing.

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 Advantageously, the inside diameter of the elastic washer is less than the inside diameter of the inner ring of the bearing.

 Preferably, the elastic washer extends radially inside a groove provided at the external periphery of a skirt that has the interface member.

 According to another form of application to a stop intended to intervene in the actuation of a friction clutch of the pushed type, the maneuvering ring is the outer ring of the bearing.

 Advantageously, the outside diameter of the elastic washer is greater than the outside diameter of the outer ring of the bearing.

 Preferably, the elastic washer extends radially inside a groove provided at the internal periphery of a skirt presented by the interface member.

 To improve the reliability and longevity of this kind of clutch release bearing, in particular when the clutch, of the pulled type, is required to transmit high powers, for example a clutch for industrial vehicles, in which the clutch release bearing is subjected to particularly intense axial tensile forces, a clutch release bearing of the aforementioned type can be provided in which the bearing is of the type with oblique contacts, the rolling elements of the bearing transmitting for example to the inner ring axial traction forces exerted on the ring external by means of the interface member and authorizing an axial movement of the external ring relative to the internal ring when axial forces in the opposite direction, called thrust, are exerted on the external ring, as described in the French patent application filed on December 30, 1999 under the number 99 16795.

 It is understood that the angular contact bearing used better withstands the axial load in tension than a simple radial contact bearing.

 The invention also relates to a friction clutch comprising a release bearing such as one of the above stops; the declutching means belong to a diaphragm.

 Other characteristics and advantages of the invention will appear on reading the following description of particular embodiments given by way of nonlimiting examples.

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 Reference will be made to the accompanying drawings, among which: - Figure 1 is an axial sectional view of a friction clutch mechanism of the pulled type comprising a conventional stop; - Figure 2 is a partial view in axial section of a stop according to the invention applicable to the mechanism of Figure 1; - Figure 3 is a view similar to Figure 2, illustrating a variant of the invention; - Figure 4 is a view similar to Figures 2 and 3 illustrating the invention applied to a stop for a clutch of the pushed type; - Figure 5 is a view similar to Figure 4 illustrating a variant of the invention.

 Figure 1 shows, as a whole, a friction clutch mechanism. This mechanism conventionally comprises a reaction plate 1 which here constitutes an engine flywheel fixed to the nose of a driving shaft 2 such as the crankshaft of an internal combustion engine. A cover 3 in the form of a bell is attached to the periphery of the reaction plate 1 while being integral in rotation with this plate.

 Inside the space delimited by the reaction plate 1 and the cover 3, are arranged in a stack along a common axis of rotation 13 coinciding with the axis of the driving shaft 2, a friction disc 4 provided at its periphery of friction linings 5, a pressure plate 6 and a diaphragm 7 exerting an elastic action on the pressure plate 6 in the direction of the reaction plate 1 by pressing on the cover 3, to tighten the linings 5 of the disc friction 4 between these two reaction plates 1 and pressure 6.

 The friction disc 4 is integral in rotation with a driven shaft 12 such as the input shaft of a gearbox and has the same axis 13 as the reaction plate 1. More precisely, the friction disc 4 is provided with an internally grooved central hub 11 which is slidably mounted on a grooved portion 14 complementary to the driven shaft 12 with which it is thus secured in rotation. In addition, beyond the grooved portion 14, the driven shaft 12 has a nose 15 which is centered and mounted for rotation on the reaction plate 1 by means of a ball bearing16.

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 The pressure plate 6 is made integral in rotation with the cover 3 by means of tangential tongues 18 which, elastic, also constitute means for returning the pressure plate 6 to the cover 3. The pressure plate 6, while being integral in rotation with the cover 3, is therefore axially displaceable relative to the latter.

 The diaphragm 7 comprises a peripheral part 8 in the form of a Belleville washer, the external periphery of which bears on the cover 3 by means of a support ring 10 forming a pivot, and the internal periphery of which bears on a circular support bead 17 of the pressure plate 6; thus, an axial thrust force is exerted on the pressure plate 6 in the direction of the reaction plate 1 in order to couple the driving shafts 2 and driven 12 in rotation when the clutch is in the engaged position. The diaphragm 7 comprises a plurality of radial fingers 9 in extension of the internal periphery of the Belleville washer part 8. In addition, the diaphragm 7 is coupled in rotation to the pressure plate 6 by means of indexing pins 19.

 Such a clutch mechanism is well known; as is known, to release the linings 5 from the friction disc 4, with a view to disengaging the clutch, it suffices to exert on the free ends of the radial fingers 9 of the diaphragm 7 a tensile force in the direction of the arrow T. This type of clutch mechanism, in which the disengagement is obtained by a traction action on the radial fingers 9 of the diaphragm 7, is, as is known, called of the "pulled" type.

 The tensile force in the direction of arrow T is produced by means of a clutch release bearing 20.

 This clutch release bearing 20 comprises a bearing with oblique contacts 21, comprising an inner ring 22, an outer ring 23 and, between these rings, a row of rolling elements 24 which are here balls. The bearing 21 being with oblique contacts, the balls 24 correctly transmit to the inner ring 22 axial forces exerted on the outer ring 23 exclusively in traction, according to arrow T, but do not transmit any axial force to the inner ring 22 when axial thrust force P, illustrated by arrow P, is exerted on the outer ring 23 in the direction of the plates 1 and 6. The balls 24 thus allow an axial movement of the outer ring 23 by

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 relative to the inner ring 22 when an axial thrust force P is exerted on the outer ring 23.

 For its coupling to the free end of the radial fingers 9 of the diaphragm 7, the inner ring 22 is extended along a connecting portion 25 which is hooked to the free end of the radial fingers 9 of the diaphragm 7 by means of a ring 26 said docking which is axially retained, on the connection portion 25, by an annular coupling ring 27 received in a notch 28 formed externally at the end of the connection portion 25 of the inner ring 22, which ring 27 forms a stop axial for the docking ring 26.

 To avoid any axial play in the connection of the connection portion 25 with the radial arms 9 of the diaphragm 7, an elastic washer 29 of the Belleville type, bearing by its internal periphery against a shoulder 30 of the connection portion 25 of the ring inner 22, elastically maintains the free end of the radial arms 9 of the diaphragm 7 in abutment against the docking ring 26.

 The outer ring 23 of the bearing 21 is coupled to an operating sleeve 31 which serves as an interface with actuation means, not shown, of the mechanical type, such as a declutching fork, or of hydraulic means, such as the operating piston '' a jack for the hydraulic control circuit, or electric. The operating sleeve 31 is slidably mounted on a tubular guide sleeve 55 of axis 13 which is traversed by the driven shaft 12 and which is integral with a clutch housing or bell 56. The sleeve 31 also has means, not shown, for cooperating with the aforementioned actuating means so as to allow the latter to exert on it an axial tensile force, according to arrow T.

 In this case, the coupling of the outer ring 23 of the bearing 21 to the operating sleeve 31 is carried out by means of a cup 32. The cup 32 is in the form of a sheet metal ring, the two ends of which have been deformed to cooperate axially with the outer ring 23 of the bearing 21 on the one hand, and with a flange 34 of the interface sleeve 31, on the other hand.

More specifically, the bowl 32 has, on one side, lugs 33 folded around the flange 34 of the operating sleeve 31, and, on the other side, a

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 annular radial rim 35 which cooperates axially with the outer ring 23 of the bearing 21. An elastic washer 36 is interposed between the transverse edge of the outer ring 23 which faces the operating sleeve 31 and a transverse bearing face 37 of the end the operating sleeve 31; the bearing 21 is thus mounted resiliently in the cup 32, with an axial clearance, in reality an axial setting, and a radial clearance, the declutching stop 20 being of the self-centering type.

 FIG. 2 shows such a stop 20 arranged according to the invention.

 As in FIG. 1, the operating ring is the outer ring 23 of the bearing 21, the inner ring 22 being the actuation ring which carries the connection portion 25.

 Here, the transverse support face 38 of the operating ring 23 cooperates with the elastic washer 36 according to a support zone located radially at a distance from the outside diameter of the elastic washer 36.

 It will be noted that seals 41 and 42 are arranged between the two rings 22, 23 and, axially, on either side of the rolling elements 24; the transverse support face 38 of the operating ring 23 is offset axially, towards the outside, relative to the seal placed on the side of said transverse support face 38, namely the seal 41, and this thanks to a machining of the outer ring 23, at the end of the latter.

 It will also be noted that this transverse bearing face 38 of the operating ring 23 has a reduced radial dimension with respect to the smallest radial dimension of the operating ring 23.

 Furthermore, the outside diameter of the elastic washer 36 is greater than the outside diameter of the outer ring 23 of the bearing 21; the elastic washer 36, provided slotted, extends radially inside a groove 39 provided at the internal periphery of a skirt 40 that has the interface member 31; the split washer 36 can be in elastic support on the bottom of the groove 39.

 Here, between the legs 33 and the annular radial rim 35 of the cup 32, the latter, which does not participate in the centering of the operating ring 23, has a change in diameter with large radii of stamping curvature, namely an inner radius greater than the thickness of the sheet:

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 the restrictions are limited and the release forces can be increased or, for equal efforts, the thickness of the sheet of the bowl reduced.

 Referring to FIG. 3, it can be seen that the clutch release bearing 120 comprises an annular hollow housing 52, a ball bearing 121, an operating sleeve 31 suitable for being subjected to the action of a control member such as '' a clutch release fork.

 The housing 52 carries the connecting element 25 and is integral with the rotating external ring 123 of the ball bearing 121.

 The operating sleeve 31 is adapted to slide along the guide sleeve 55.

 Here, it is the inner ring 122 of the ball bearing 121 which is axially secured to the operating sleeve 31; thus, an axial connection is ensured between said bearing 121 and said operating sleeve 31 going from the connection portion 25 to the operating sleeve 31.

 Here, the housing 52 is made of stamped sheet metal being of annular shape; it comprises a skirt 54, of axial orientation, surrounding without play the outer ring 123 of the ball bearing 121. The skirt 54 is extended at one of its ends by a fallen edge 57 directed radially towards the axis of the together, said dropped edge 57 being extended towards the axis of the assembly by a connection portion 58 of tortuous and inclined shape, which is connected to a generally cylindrical portion in the form of a socket 25 constituting the connection portion 25.

 It will be noted that the other end of the skirt 54, initially straight, is folded radially inwards to trap the outer ring 123 of the ball bearing 121.

 This folded end allows the formation of a support for the clutch release fork, not shown, during the snap assembly of the clutch release bearing assembly.

 Thus, this outer ring 123 is fixed to the housing 52 by crimping, said ring being trapped by the fallen edge 57, the skirt 54 and the other end of the skirt 54 folded down.

 Of course, instead of folding the end of the skirt 54, the outer ring 123 of the bearing 121 can be axially wedged using a circlip.

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 At its internal periphery, the operating sleeve 31, here in cast iron, carries a sliding ring 43 made of anti-friction material, for example plastic, for good sliding along the guide sleeve 55.

 This ring 43 is secured to the sleeve 31 by force engagement, said ring having a rib 44 engaged in a generally trapezoidal groove 45, which has the internal bore of the sleeve 31 internally.

 At its outer periphery, this sleeve 31 carries two shoulders 59.60 offset axially relative to one another for mounting the internal ring 122 of the bearing 121. More specifically, the sleeve 31 has a change in diameter for formation of '' a shoulder 60.

 This change in diameter affects the sleeve 31 at its free end which has a groove for mounting a cliclips 61.

 Thus there is formed, between the shoulder 60 and the circlip 61, forming the shoulder, a groove allowing the mounting of the internal ring 122 of the ball bearing 121. An elastic means with axial action 62, here a wavy washer, is supported. on the shoulder 60 and on one of the edges of the inner ring 122 of the bearing 121, to urge the other edge of the inner ring 122 in contact with the circlip 61.

 The inner ring 122 of the bearing 121 is mounted with clearance relative to the sleeve 31 and can move radially with the housing 52 relative to the sleeve 31 under the control of the Belleville washer 62.

 Thus a self-centering type clutch release bearing is created with axial subjection of the bearing 121 to the sleeve 31. When disengaging the clutch, the tensile force is transmitted to the circlips 61, to the bearing 121 and, to the bearing 121 , to the connecting portion 125 and to the docking ring 26.

 Here, it is therefore the internal ring 122 of the bearing 121 which is the operating ring; the internal diameter of the elastic washer 62 is less than the internal diameter of said internal ring 122.

 In the form shown, the elastic washer 62 extends radially inside a groove 63 provided at the external periphery of a central part 64 in the form of a skirt which has the interface member 31.

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 Of course, the invention also applies to a declutching stop intended to intervene in the actuation of a friction clutch of the pushed type.

 This is the case of the stop 220 shown in Figure 4; here, the operating ring is the outer ring 223 of the bearing 221 with oblique contacts; it is the internal ring 222 which cooperates directly with the fingers of the diaphragm 7.

 The Belleville washer 162 with which the end of the outer ring 223 cooperates is placed at the front of the interface member or operating sleeve 31, that is to say on the side of the fingers of the diaphragm 7; said Belleville washer 162 is supported on the interface member 31 by means of a closure plate 160 which it carries at the front; here, the external periphery of the closure plate 160 is crimped onto an external peripheral shoulder 161 at the end of the external skirt 166 of said member 31.

 The elastic washer 162 has an elastic diameter which is greater than the outer diameter of the outer ring 223 of the bearing 221, which extends radially inside a groove 165 provided at the inner periphery of the outer skirt 166 of the organ 31.

 According to the variant of Figure 5, the closure plate 160 placed at the end of the skirt 166 of the member 31 is held axially relative to the latter by means of a redent 163, directed radially inwards, obtained by crimping from the end of the skirt 166, and bordering the groove 165

Claims (15)

1. Release bearing intended to intervene in the actuation of a friction clutch, of the type comprising a bearing (21,121, 221) having two rings (22,122, 222-23,123, 223) and rolling elements (24), l 'one (23,122, 223) of the so-called operating rings cooperating with an interface member (31) intended to be actuated by operating means capable of exerting on this interface member (31) a force in the axial direction of the bearing (21,121, 221), which force is transmitted by the rolling elements (24) to the other (22,123, 223) said actuation ring cooperating with the declutching means (7) of the clutch, said bearing (21,121, 221) being mounted resiliently with respect to the interface member (31) with axial and radial play, said stop being of the self-centering type, an elastic washer (36, 62, 162) being disposed axially between a transverse face of support (38) of the operating ring (23,122, 223) and a transverse face of support (37,60, 160) linked to the interface member (31), characterized in that the transverse support face (38) of the operating ring (23,122, 223) cooperates with the elastic washer ( 36, 60, 160) according to a support zone located radially away from the diameter, outside or inside, of centering of the elastic washer (36, 62, 162).  2. Stop according to claim 1, characterized in that the transverse bearing face (38) of the operating ring (23,122, 223) is offset axially outwardly relative to the seal (41) disposed transversely, between the two rings (22,122, 222-23,123, 223) of the bearing (21,121, 221, on the side of said transverse bearing face (38).  3. Stop according to one of claims 1 or 2, characterized in that the transverse bearing face (38) of the operating ring (23,122, 223) has a reduced radial dimension compared to the smallest radial dimension of the operating ring (23,122, 223).  4. Stopper according to one of claims 1 to 3, intended to intervene in the actuation of a friction clutch of the pulled type, characterized in that the operating ring (23) is the outer ring of the bearing (21 ).  5. Stopper according to claim 4, characterized in that the outside diameter of the elastic washer (36) is greater than the outside diameter of the outer ring (23) of the bearing (21). <Desc / Clms Page number 13>  6. Stopper according to claim 5, characterized in that the elastic washer (36) extends radially inside a groove (39) provided at the internal periphery of a skirt (40) that has the interface member (31).  7. Stopper according to one of claims 1 to 3, intended to intervene in the actuation of a friction clutch of the pulled type, characterized in that the operating ring is the inner ring (122) of the bearing (121 ).  8. Stopper according to claim 7, characterized in that the inside diameter of the elastic washer (62) is less than the inside diameter of the inner ring (122) of the bearing (121).  9. Stopper according to claim 8, characterized in that the elastic washer (62) extends radially inside a groove (63) provided at the external periphery of a central part (64) in the form of skirt presented by the interface member (31).  10. Stopper according to one of claims 1 to 3, intended to intervene in the actuation of a friction clutch of the pushed type, characterized in that the operating ring is the outer ring (223) of the bearing (221 ).  11. Stopper according to claim 10, characterized in that the outside diameter of the elastic washer (162) is greater than the outside diameter of the outer ring (223) of the bearing (221).  12. Stop according to claim 11, characterized in that the elastic washer (162) extends radially inside a groove (165) provided at the internal periphery of a skirt (166) that has the interface member (31).  13. Stopper according to one of claims 1 to 12, characterized in that the bearing (21,121, 221) is of the type with oblique contacts.  14. Friction clutch comprising a stop (20,120, 220) according to one of the preceding claims.  15. Friction clutch according to claim 14, characterized in that the declutching means belong to a diaphragm (7).