FR2735824A1 - FRICTION CLUTCH WITH INTERCHANGEABLE FRICTION DISC - Google Patents

Abstract

Improvement of a disc wear compensation system to facilitate maintenance. According to the invention, the two elements (16, 25) of the wear adjuster, provided with ramps (27, 28) and attached to elastic means (30) comprise temporary anchoring points (42, 44) for the elastic means.

Description

"Friction clutch, interchangeable friction disk" The invention

  relates to a friction clutch and more particularly relates to an improvement made to the means of catching wear thereof for ease of maintenance, in particular to allow to easily change the used friction disc. A friction clutch comprises in particular, integral in rotation, at least one pressure plate, a cover and a diaphragm, the latter being actuated axially by a clutch abutment. The diaphragm applies to a

  Crown-shaped bead supported by the tray.

  The latter, biased by the diaphragm is in contact, in the engaged state, with a friction disc. This disc wears progressively, which modifies little by little the axial positions of the elements and, consequently, the conditions of action of the diaphragm. The diaphragm forms a unitary assembly to the mechanism with the lid and the pressure plate. This assembly is attached to a reaction plate wedged in rotation on a driving shaft, while the friction disc is rotatably mounted on a driven shaft being adapted to be clamped between the

  pressure and reaction trays.

  In this type of clutch, there is known a wear compensating arrangement comprising two elements provided with annular ramps respectively nested, and elastic means attached to respective anchor points of

  two elements to solicit circumferentially.

  More specifically, the wear-compensating arrangement incorporates the abovementioned bead and interposes axially between it and said pressure plate. Tray stroke limiting means, which can be automatically moved according to the wear of the friction disk, are furthermore provided between said plate and said cover. The presence of elastic means urging the two elements in the direction of their axial separation by the cooperation of the annular ramps is a disadvantage for maintenance. Indeed, if the friction disc is worn, the wear compensating arrangement opposes the change of this disc. The current practice is to change the entire mechanism, including the tray, the lid etc ... This results in a significant maintenance cost. The invention makes it possible to eliminate this drawback. The basic idea of the invention consists in reversing the direction of action of the elastic means acting on said wear compensating arrangement to bring the two elements equipped with annular ramps back to their initial state without effort, where the ramps are totally nested, which facilitates the release of the used friction disc and its replacement. More specifically, the invention therefore relates to a friction clutch provided with a wear-compensating arrangement comprising two elements provided with annular ramps respectively imbricated, circumferentially biased by elastic means attached to respective anchor points, characterized in that said elements comprise temporary anchoring points for said elastic means, making it possible to invert their circumferential biasing action during a maintenance operation. Furthermore, changing the friction disc also involves bringing the wear compensating arrangement back into its initial state; this result is obtained automatically during the change operation of the

friction disc.

  The invention will be better understood and other advantages thereof will appear more clearly in the light of the

  following description of an embodiment of a

  friction clutch according to its principle, given only by way of example and with reference to the accompanying drawings in which: - Figure 1 is a partial view in half section of a friction clutch according to the invention, assumed in new condition; FIG. 2 is a partial diagrammatic view, in a radial direction, of the two ramp elements of the wear-compensating arrangement and the associated elastic means, the elements being represented in the fully nested state of said ramps, when the clutch is new; - Figure 3 is a view similar to Figure 2, illustrating the same elements when the friction disc is worn, said wear being compensated by the relative displacement of the ramps; - Figure 4 is a view similar to Figure 3, illustrating the modification of the anchoring of the elastic means to facilitate the change of the friction disc; and FIG. 5 is a view similar to FIG. 4, illustrating the result of this operation resulting in

  a reset of the wear compensating means.

  Referring more particularly to Figure 1, there is shown partially a friction clutch and more particularly the elements related to the invention, namely a friction disc 11, a pressure plate 12 and a diaphragm 13, metallic disc-shaped, axially acting spring acting on the plate by means of an annular bead 15 defined on a field of a crown 16 carried by the plate 12. All these elements are housed in a cover 17. More specifically, the disc 11 has at its outer periphery friction linings adapted to be clamped between the plate 12 and a reaction plate, not shown, integral in rotation with a driving shaft, such as the crankshaft. of the vehicle engine. Said support cord 15 has a tapered edge on which the diaphragm 13 is applied. The latter pivots in the vicinity of its outer edge on a rod 20 fixed inside the lid. Conventionally, the diaphragm is operated

  axially by a clutch abutment not shown, it

  even moved by a mechanism related to the clutch pedal.

  The plate 12, the diaphragm 13, the support cord 15 and the lid 17 are integral in rotation, the plate being rotatably connected to the lid with axial mobility by conventional tangential tongues, not shown, constituting elastic means with axial action. tending to disengage the plate of the friction disc 11, in the disengaged position, while the diaphragm 13 is rotatably connected to the plate 12, by pins (not shown) anchored in the pressure plate and extending towards the diaphragm (axially ) towards the bottom of the cover to cooperate with the edges of the enlarged orifices 1 that has the diaphragm 13 to the inner periphery of its Belleville washer, said orifices forming the ends of the slots separating in pairs the fingers of the diaphragm. A wear compensating arrangement 21 is provided to compensate for the wear of the friction disc 11 and to a lesser extent the wear of the friction faces of the pressure plates 12 and reaction. It comprises, on the one hand, a compensation arrangement 22 arranged between the bead 15 and the pressure plate 12 and, on the other hand, stroke limiting means 24 of said plate, movable under the solicitation of the diaphragm in the event of 'wear. The stroke limiting means are arranged between the plateau of

pressure 12 and the lid 17.

  The compensating assembly 22 comprises two elements provided with annular (complementary) annular ramps respectively nested. One of the elements is or comprises the bead 15 (it is in fact the ring 16) while the other element is mounted on the pressure plate 12 or is part thereof. In the example shown, it is an intermediate ring 25 housed in a groove circular contour, centered, said tray. The ring 16 of the cord comprises dorsally ramps 27. The intermediate ring 25 comprises frontally ramps 28. Elastic means, constituted here by at least one coil spring 30, are mounted between the two elements (that is to say the crowns) so as to urge circumferentially in a direction such that, the ramps sliding on each other, there is a gradual increase in the axial distance separating the plate 12 and the bead 15. The or each spring 30 is therefore attached to respective anchoring points 32, 33 of the two rings, as shown in Figure 2. Several springs 30 are advantageously distributed circumferentially around the rings. It is preferable for the springs to extend inside the rings 16, 25 because in FIG. 1 the clutch is of the pulled type, the clutch release bearing acting in traction on

  the inner end of the fingers of the diaphragm.

  Furthermore, the stroke limiting means 24 comprise tabs 36 fixed to the cover and engaged in notches 39 formed in the thickness of the plate 12. These notches may be replaced by a peripheral groove of said plate. Each tab 36, with a square section, is fixed to the cover by means of a rivet 37 passing through an oblong hole 38 of said tab. An elastic clamping washer 40 is interposed between the tab and the rivet head. The clamping is such that the tabs can move axially in the direction indicated by the arrow F under the action of the plate itself urged by the diaphragm, at the time of a clutch if friction disk wear has occurred . However, the legs can not return during a disengagement operation, in the opposite direction under the action of the plate urged by the tangential tongues. It is therefore conceivable that the tabs 36 move progressively parallel to the direction of the arrow F, throughout the life of the friction disc, the washer 40,

  here of the Belleville type, being tared accordingly.

  According to an important characteristic of the invention, the elements 16, 25 provided with annular ramps 27, 28, mutually cooperating with each other, comprise temporary anchoring points 42, 44 for said resilient means 30, making it possible to reverse their solicitation action, circumferential during a maintenance operation. These temporary anchoring points are visible in FIGS. 2 to 5. It should be noted that, in the example shown, in the fully embedded state of said ramps, shown in FIG. 2, that is to say when the disk friction is new, a temporary anchoring point 44 on one element is shifted circumferentially relative to a corresponding normal anchor point 32, on the other element. The offset is such that, after wear of the friction disk compensated by said wear compensating arrangement, the two anchoring points 32, 44 are found substantially opposite one another. Conversely, in the fully nested state of said ramps (FIG. 2), the other temporary anchoring point 42 is substantially

  look at the other normal anchor 33.

  The operations of changing the worn friction disc, without having to change the other parts of the clutch will now be described with reference

in Figures 3 to 5.

  Figure 3 shows the positions of the two ring-shaped elements 16, 25 at the end of the life of the friction disk. Comparing FIGS. 2 and 3, it is realized that the two rings have progressively rotated relative to one another, which has resulted, due to the cooperation of the nested ramps, by an increase in the axial distance separating the tray from the support line of the cord. Throughout this period, the temporary anchor point 44 has moved slowly until it comes substantially opposite the corresponding normal anchor point 32. After disassembling the mechanism, formed unitarily by the cover 17, the plate 12 and the diaphragm 13 through the tangential tongues and the aforementioned pins visible for example in Figures 4, 14 and 18 of FR-A-2 463 874 press the diaphragm to simulate a disengagement. The anchorage of the spring or springs is then changed as illustrated by comparing FIGS. 3 and 4. The force required to tighten the spring or springs 30 is small. This maneuver results in an opposite rotation of the two elements 16, provided with ramps, as appears by comparing FIGS. 4 and 5. This resetting of the compensation assembly makes it possible to easily change the friction disk. It is then sufficient to release the diaphragm and reattach the springs to their normal anchoring points 32, 33.

Claims (4)

  A friction clutch provided with a wear-compensating arrangement comprising two elements (16, 25) provided with annular ramps (27, 28) respectively imbricated, circumferentially biased by resilient means (30) attached to dots anchoring (32, 33) respective, characterized in that said elements (16, 25) comprise temporary anchoring points (42, 44) for said elastic means, allowing to invert their circumferential biasing action during an operation of maintenance.   2- friction clutch according to claim 1, characterized in that, in the fully nested state of said ramps, a temporary anchoring point (44) on an element is offset circumferentially relative to a normal anchorage point (32). ) corresponding, on the other element, the offset being such that, after wear compensated by said wear compensating arrangement, the two anchoring points (32, 44) are found substantially opposite one of the other.   3- friction clutch according to claim 2, characterized in that, in the fully nested state of said ramps, the other temporary anchoring point (42) is substantially opposite the other anchor point normal (33).   4- friction clutch according to one of the claims   characterized in that, in a manner known per se, one of the aforementioned elements (16) constitutes or comprises the bead (15) of the diaphragm of the clutch and in that the other element mentioned above (25) ) is mounted on the board   pressure or is part of it.