FR3016669A1 - FRICTION CLUTCH AND METHOD FOR MANUFACTURING A FRICTION CLUTCH - Google Patents

Abstract

The invention relates to a friction clutch (10) for coupling a drive shaft of a motor vehicle engine to at least one input shaft of a motor vehicle gearbox. It comprises a clutch cover (16) for at least partially covering the friction clutch (10), a counter plate (12) secured to the clutch cover (16) via a means fastener (14), a pressure plate (30) axially movable relative to the counter plate (12) for frictionally pressing a clutch disc (32) between the counter plate (12) and the tray pressure device (30), a lever member (28) rotatably supported at the clutch cover (16) for moving the pressure plate (30), and a locking ring (22). pressed with a radially external preload against the clutch cover (16) and the counter plate (12).

Description

The present invention relates to a friction clutch and a method for manufacturing a friction clutch, by means of which a drive shaft of a vehicle engine. automobile can be coupled to at least one gearbox input shaft of a motor vehicle gearbox. From DE 10 2012 207 037 A1 it is known a friction clutch, for which a plurality of lever segments for axially displacing a pressure plate in the radial direction are guided through openings in a clutch cover connected to a friction clutch. a counter plateau. The lever segments may be pivoted by an actuating system to move the pressure plate relative to the counter plate thereby frictionally pressing a clutch plate between the pressure plate and the counter plate. The lever segments are held by a circumferentially closed wire ring, which wire ring rests radially outwardly on the radially protruding side of the lever segments and is intended to prevent expansion of the segments. lever under the influence of centrifugal force. It is necessary to continuously maintain the power ratios when operating a substantially constant friction clutch. It is an object of the present invention to provide measurements which enable a friction clutch having a large proportion of substantially constant power ratios upon actuation of the friction clutch. The object of the invention is achieved according to the invention by a friction clutch for coupling a drive shaft of a motor vehicle engine to at least one gearbox input shaft of a box. motor vehicle gears, comprising a clutch cover for at least partially covering the friction clutch, a counter plate secured to the clutch cover by means of a fastening means, a pressure plate movable axially relative to the counter plate for frictionally pressing a clutch disc between the counter plate and the pressure plate, a lever member rotatably supported at the clutch cover, in particular configured in the form of a spring washer, for moving the pressure plate and a clamping ring pressed with a preload radially externally at the clutch cover and at the nive counter-plate, for releasably fixing the clutch cover relative to the counter plate in a position under the influence of centrifugal force, and also by a method for producing a friction clutch, in a the frame of which the locking ring is positioned in the axial direction between the clutch cover and the counter-plate, the clutch cover being positioned by the locking ring at a distance from the counter plate, and the clutch cover being subsequently fixed to the counter-plate by means of the fixing means, the axial distance between the clutch cover and the counterplate being reduced during the fixing and the locking ring 5 being enlarged in the axial direction by the clutch cover and / or by the counter plate. Preferred embodiments of the invention are set forth in the following detailed description, particularly with reference to the preferred embodiments of the invention. According to the invention, a friction clutch for coupling a drive shaft of a motor vehicle engine to at least one gearbox input shaft of a motor vehicle gearbox is provided with a clutch cover for at least partially covering the friction clutch, a counter plate secured to the clutch cover by means of a fixing means, a pressure plate axially movable relative to the counter plate and for frictionally pressing a clutch disc between the counter plate and the pressure plate, a lever member rotatably supported at the clutch cover, in particular configured under the counter plate; form of a spring washer for moving the pressure plate, and a locking ring pressed by means of a prestressing externally radially against the clutch cover and the counter plate, serving as a fixed r relatively in position the clutch cover relative to the counter plate under the influence of the centrifugal force.

In the present context, use is made of the knowledge that the counter plate and the clutch cover can modify their relative position under the influence of the centrifugal force, which makes it possible to move in the same manner the pivot point of the clutch. lever element due to displacement due to the centrifugal force of the clutch cover. The power ratios used to actuate the friction clutch can change due to the displacement of the pivot point of the lever element in that, for example the lifting stroke of the pressure plate, the angular position of the element of lever, the pivot angle required for actuation of the lever element or the like vary. As a result, the force ratios when the friction clutch is actuated vary as a function of the speed of rotation of the friction clutch moment by the influences of the centrifugal force. It has been admitted that it is possible in principle that the modular group formed by the counterplate and the clutch cover can pivot resiliently with respect to a radial plane under the influence of the centrifugal force and / or that the clutch cover can perform under the influence of the centrifugal force a radial offset relative to the counter plate. The locking ring resting with a preload both at the counter plate and at the clutch cover can impart a locking force oriented in the opposite direction to the centrifugal force radially inwardly on the counter. platter and clutch cover. Thus, the influence of the centrifugal force exerted on the counter plate and the clutch cover can be compensated at least in part. The locking ring resting with a preload both at the counter plate and at the clutch cover can thus stiffen the modular unit formed from the counter plate and the clutch cover and prevent an offset radial direction of the clutch cover relative to the counter-plate under the influence of the centrifugal force so as to avoid a variation, related to the centrifugal force, of the force ratios by the displacement due to the centrifugal force of the pivot point of the lever element and so as to allow a friction clutch having a high proportion of substantially constant power ratios upon actuation of the friction clutch. The lever element may be in the form of a lever spring configured substantially in the form of a spring washer. The lever member may have a spring washer ring that serves as a spring washer, from which spring blades can project radially inwardly through which a particularly hydraulic actuating system can induce an actuating force for moving the pressure plate. The lever element may for example be pivoted for example at a peripheral lug protruding, for example produced by stamping, the clutch cover, around a pivot point substantially of linear shape in the direction of the periphery, the conicity of the lever element configured in the manner of a spring washer in particular can vary during pivoting. In addition or alternatively, a tilting ring bearing at the level of the clutch cover, in particular closed in the circumferential direction, may be provided, which constitutes for the lever element a pivot point substantially of linear form in the sense of the periphery. It is also possible to make the lever element by several different lever segments placed at the clutch cover so as to be pivotable, as shown in DE 10 2012 207 037 A1, the reference to the contents of said document forming part of the invention. The counter plate can be coupled in particular to the drive shaft of the motor vehicle engine, while the clutch disc can be coupled to a gearbox input shaft of the motor vehicle gearbox. . The clutch cover is connected in particular integrally in rotation against the plate. In particular, the clutch cover is connected, in particular in a fixed position, to the counterplate substantially integrally in displacement at a correspondingly high rotational speed irrespective of the influences of the centrifugal force. For example, the clutch cover may have a passage opening for the fastening means to clamp the clutch cover to the counterplate by means of the fastening means, the fastening means being inserted into the opening The blocking ring makes it possible to avoid a possible displacement that can be envisaged in principle because of this clearance of the clutch cover with respect to the counter-plate and / or the fastening means when it is It is possible to overcome dominant clamping forces under the influence of a correspondingly high centrifugal force. In particular, the locking ring has a greater rigidity than the pressure plate and / or the clutch cover.

The locking ring may be manufactured in particular from a suitably alloyed steel and / or heat-treated steel. The locking ring can be expanded, in the mounted state, elastically radially outwardly so that the locking ring can rest at the clutch cover and the counterplate with the aid of sufficient prestressing, with a blocking force directed radially inwardly. The locking ring can rest flat or in a point or linear manner at the counter plate and / or the clutch cover by a contact face or by several contact faces. Locking rings of different shape and having different cross-sectional faces can fulfill the function of the locking ring, another face of respective cross section of the locking ring may be useful depending on the application case . In particular, the clutch cover and the counterplate form a common housing groove, in particular circumferentially closed, for accommodating the locking ring. The locking ring can be depressed thereby at least in part in the blocking groove. In particular, it is possible to use as oblique plane bearing faces, directed towards the locking ring, the housing groove, at which the locking ring can slide radially outwardly during attaching the clutch cover to the counter plate which allows to expand elastically radially outwardly the locking ring. Thus, it is possible to generate the preload of the locking ring already during the attachment of the clutch cover to the counter plate without requiring an additional machining step isolated for this purpose. In addition, the locking ring can be positioned in the housing groove in a defined axial position. The housing groove preferably has bearing faces directed towards the locking ring, the respective bearing face being formed in a planar manner and / or in a rounded manner, in particular in a convex manner. The planarly configured support faces may form an oblique plane having a constant slope so that the locking ring can be stretched with a radius extension proportional to the variation of the axial distance between the clutch cover and the counter plateau during fixation. When the bearing faces are formed in a curved manner, in particular in a rounded manner, the result is an oblique plane having a variable slope. In the case of a convex configuration, the locking ring can be stretched at the beginning of the fastening operation disproportionately so that the locking ring is prestressed particularly rapidly. Particularly preferably, the locking ring has a thickness D in the radial direction, the locking ring being housed in the housing groove with a proportion d in the radial direction, here applying 0.10 d / D 1.00, in particular 0.40 d / D 0.90, preferably 0.50 d / D 0.80 and most preferably 0.60 d / D 0.75. The locking ring can thus reach the housing groove with a significant proportion, in particular in all, so that the need in radial position defined by the locking ring can remain low and be minimized. The locking ring is in particular round-shaped, in particular convexly, at an inner side radially inwards. A sharp-edged cross-sectional shape of the locking ring can thus be avoided, so that the locking ring does not have to engage the housing groove with sharp-edged corners. The pressure of faces between the locking ring and the counter plate and / or the clutch cover, in particular within the housing groove, can thus be reduced. An elastic deformation of the locking ring under the influence of the centrifugal force may result in the contact face between the locking ring and the pressure plate and / or the clutch cover becoming larger. which achieves correspondingly high rigidity under the influence of centrifugal force. The locking ring is preferably closed in the circumferential direction. The locking ring 5 does not need to be in the form of a loop surrounding only part of the periphery, for which it is necessary to provide corresponding engagement means by complementarity of form. Instead, the locking ring can be configured and made particularly easily, for example in the form of a closed wire ring or a closed metal band. Particularly preferably, the securing means extends in the axial direction, the securing means configured in particular in the form of a screw or rivet securing by complementary shape and / or by friction the cover. clutch on the counter plate. Due to the extension of the fixing means 20 in the axial direction, it is possible to allow, for sufficiently large centrifugal forces, a radial offset of the clutch cover relative to the counter plate, which is then prevented by the locking ring. The requirements, in particular with regard to the pressure force to be applied by the fastening means, can therefore remain low. The attachment means can be developed for example for the function of preventing only a spacing of the clutch cover from the counter plate.

The counter plate is made especially from cast iron and the clutch cover is made from steel. The counter plate and the clutch cover can be manufactured thereby at lower cost. In particular, the locking ring makes it possible for the counterplate and the clutch cover to exhibit, due to a different material structure, a different expansion behavior under the influence of the centrifugal force.

The invention further relates to a method for manufacturing a friction clutch, which can be designed and improved as described above, wherein the locking ring is axially positioned between the clutch cover and the counter plate, the clutch cover being positioned spaced from the counter plate by the locking ring and the clutch cover being subsequently secured to the counter plate by means of the fixing means. the axial distance between the clutch cover and the counterplate being reduced during attachment and the locking ring being radially expanded by the clutch cover and / or the counterplate. The process can in particular be designed and improved as it has been exposed using the friction clutch. The locking ring resting after fastening with a preload both at the counter-plate and the clutch cover can stiffen the modular unit formed from the counter plate and the clutch cover and prevent a radial offset. of the clutch cover relative to the counterplate under the influence of the centrifugal force so that a variation related to the centrifugal force of the force ratios is avoided by a pivot point, displaced due to the centrifugal force, of the lever element and that it is possible to provide a friction clutch with a high proportion of substantially constant force ratios upon actuation of the friction clutch. The locking ring slides in particular during attachment to an oblique plane formed by the clutch cover and / or the counter-plate. A clamping of the locking ring between the clutch cover and the counter plate can thus be avoided. In addition, the locking ring can slide radially outwardly from the oblique plane during attachment of the clutch cover to the counterplate thereby extending the locking ring resiliently to outside radially. Thus, it is possible to generate already during the fixing of the clutch cover against the platen the prestressing of the locking ring, without requiring for this purpose a separate machining step. The present invention is explained hereinafter by way of example with reference to the accompanying drawings, with the aid of preferred embodiments, the features illustrated below being able to represent both separately and in combination with one another. of the invention. It is possible to see: FIG. 1: a diagrammatic section of part of a first embodiment of a friction clutch during assembly; Figure 2 is a diagrammatic section of the friction clutch of Figure 1 after mounting; Figure 3a: a schematic sectional view of a detail of a second embodiment alternatively proposed with respect to the friction clutch of Figure 1 during assembly; Fig. 3b: a schematic sectional view of the friction clutch of Fig. 3a after mounting; Figure 4a: a schematic section of a detail of a third embodiment alternatively proposed with respect to the friction clutch of Figure 1; Figure 4b: a schematic sectional view of the friction clutch of Figure 4a after mounting; Figure 5a: a schematic sectional view of a detail of a fourth alternative embodiment of the friction clutch of Figure 1 during assembly; Figure 5b: a schematic section of the friction clutch of Figure 5a after assembly; and FIG. 6 is a schematic perspective sectional view of the friction clutch of FIG. 1. The friction clutch 10 illustrated in a simplified manner in FIG. 1 has a counter plate 12 made in particular from cast iron. steel, which can be connected to a drive shaft of a motor vehicle engine, which counter plate can be screwed, in the embodiment shown, with the aid of a fixing means 14 configured under the form of a screw, to a clutch cover 16 preferably made from steel. The clutch cover 16 has a passage opening 18, through which the fastening means 14 can be plugged with a clearance. The counter-plate 12 and the clutch cover 16 have, at their directed axial sides, the to each other, radially outside, a recess limited respectively by a rounded bearing surface 20. A peripherally closed locking ring 22 is positioned between the counter plate 12 and the clutch cover 16 in the region of the bearing faces 20. When in the relative position shown in FIG. clutch cover 16 is screwed to the counter-plate 12, the locking ring 22 can be radially extended outwardly and can be inserted at least partly in a housing groove 24 made by the bearing faces 20 in the screwed position illustrated in Figure 2. In this case, the contour of the bearing faces 20 may correspond to the contour of the locking ring 22 so that it is possible to make a flat contact between the ring 22 and the bearing faces 20. In this stretched position, the locking ring 22 can rest with a preload both at the counter plate 12 and at the clutch cover 16. When the friction clutch 12 rotates about an axis of rotation 26, for example the clutch cover 16 can, starting from a sufficiently high rotational speed and from associated centrifugal forces, have a tendency to widen outward radially more strongly than the counter plate 12 in despite the clamping force applied by the fastening means 14, in the framework of the clearance provided between the passage opening 18 and the fixing means 14. Nevertheless, the locking ring 22 pressed with some prestressing can prevent this variation due to the centrifugal force of the relative position so that in particular a lever element 28 rotatably abutting at the level of the clutch cover 16 also retains under the influence of the centrifugal force its relative position, in particular its pivot point, relative to the counter-plateau.

The displacement of a pressure plate 30 movable by the lever member 28 relative to the counter plate 12 to frictionally press a clutch disc 32 coupled to a transmission input shaft between the Against the plate 12 and the pressure plate 30 can therefore take place also at various speeds of rotation and at particularly high speeds of rotation in essentially constant power ratios when the friction clutch 10 is actuated. which generally can be felt generally as a comfort by the driver of a motor vehicle equipped with a friction clutch 10 of this type. In the case of the embodiment shown in FIGS. 1 and 2 of the friction clutch 10, the locking ring 22 has a circular cross-section, while the bearing faces 20 form a housing groove. 24 closed in the circumferential direction and provided with a cross section of substantially semicircular shape.

As can be seen in FIGS. 3a and 3b, the bearing faces 20 can, in comparison with the embodiment, illustrated in FIGS. 1 and 2, of the friction clutch 10, be configured in the form of an oblique plane with a constant slope so that a housing groove 24 having a substantially V-shaped cross section results as can be seen in FIGS. 4a and 4b, with respect to the illustrated embodiment in FIGS. 3a and 3b, the friction clutch 10, the locking ring 22 can be executed in a rounded manner at an inner side directed towards the housing groove 24 and rectilinearly at the level of an outer side moving away from the housing groove 24. The contact of the locking ring 22 at the bearing faces 22 can thus be done with a larger radius so that it is possible to arrange, after an elastic deformation of the locking ring 22 under the influence of the centrifugal force, more quickly a correspondingly larger contact surface between the locking ring 22 and the counter plate 12 and / or the clutch cover 16, which allows reduce the pressure of the faces. In the case of the embodiment, illustrated in FIGS. 5a and 5b, of the friction clutch 10, the locking ring 22 has a substantially quadrangular cross-section with rounded corner edges. In addition, the bearing faces 20 are convexly configured. In particular, it is possible to combine all the cross-sections, shown in the figures, of the locking ring 22 with all the bearing faces 20 and housing grooves 24 shown in the figures. As can be seen in FIG. 6, the friction clutch 10 may also have two pressure plates 30 arranged one behind the other in the axial direction to frictionally press two clutch disks 32. this effect, a single lever element 28 is necessary to move the two pressure plates relative to the counter plate 12 in order to press the two clutch disks 32.

Of course, the invention is not limited to the embodiments described above and shown, from which we can provide other modes and other embodiments, without departing from the scope of the invention. invention.

Claims (10)

REVENDICATIONS1. A friction clutch (10) for coupling a drive shaft of a motor vehicle engine to at least one transmission input shaft of a motor vehicle gearbox, comprising a clutch cover ( 16) for at least partially covering the friction clutch (10), a counter plate (12) secured to the clutch cover (16) via a fastening means (14), a plate pressure plate (30) axially movable relative to the counter plate (12) for frictionally pressing a clutch plate (32) between the counter plate (12) and the pressure plate (30), a lever element (28) rotatably supported at the clutch cover (16), in particular configured as a spring washer, for moving the pressure plate (30) and a ring blocking device (22) pressed with a radially external preload against the clutch cover (16) e t the counter-plate (12), used to relatively fix in position the clutch cover (16) relative to the counter plate (12) under the influence of the centrifugal force. 2. friction clutch (10) according to claim 1, characterized in that the clutch cover (16) and the counterplate (12) form a common housing groove (24) particularly closed in the direction of the periphery , serving to house the locking ring (22). 3. Friction clutch (10) according to claim 2, characterized in that the housing groove (24) has bearing faces (20) directed towards the locking ring (22), the bearing face ( 20) being formed flat and / or rounded, in particular convexly. 4. Clutch friction (10) according to claim 2 or 3, characterized in that the locking ring (22) has a thickness D in the radial direction, the locking ring (22) being housed in the groove of housing (24) with a proportion d in the radial direction, here applying 0,10 d / D 1,00, in particular 0,40 d / D 0,90, preferably 0,50 d / D 0,80 and particularly preferably 0.60 d / D 0.75. The friction clutch (10) according to any one of claims 1 to 4, characterized in that the locking ring (22) is configured at an inwardly radially inwardly directed inner side. , in particular in a convex manner. The friction clutch (10) according to any one of claims 1 to 5, characterized in that the locking ring (22) is closed in the circumferential direction. A friction clutch (10) as claimed in any one of claims 1 to 6, characterized in that the securing means (14) extends in the axial direction, the securing means (14) configured in particular under in the form of a screw or a rivet attaching the clutch cover (16) to the counterplate (12) by complementary shape and / or friction. The friction clutch (10) according to any one of claims 1 to 7, characterized in that the counter plate (12) is made from cast iron and the clutch cover (16) is made from 'steel. A method for manufacturing a friction clutch (10) according to any one of claims 1 to 8, wherein the locking ring (22) is axially positioned between the clutch cover (16). ) and the counter plate (12), the clutch cover (16) being positioned by the locking ring (22) at a distance from the counter plate (12), and the clutch cover (16). being subsequently secured to the counter-plate (12) by means of the fastening means (14), the axial distance between the clutch cover (16) and the counter plate (12) being reduced during the fixation and the locking ring (22) being radially expanded by the clutch cover (16) and / or by the counter plate (12). 10. A method according to claim 9, in which the locking ring (22) slides, during fixing, on an oblique plane formed by the clutch cover (16) and / or the counter-plate. (12).