FRICTION CLUTCHES FOR RESETTING DEVICE FOR WEARING OF FRICTION STICKS, PARTICULARLY FOR AUTOMOTIVE VEHICLES
DESCRIPTIVE MEMORY
The present invention relates to a friction clutch, in particular for automotive vehicle, and refers specifically to a clutch equipped with a device for compensating for deterioration caused mainly by the wear of at least one friction lining, said device, as Subsequently designated as a device of '-adjustment of wear, it is activated as wear occurs in one or several friction linings. A classic friction clutch generally comprises a reaction disk forming part of a flywheel, possibly in two parts for the formation of a damping flywheel or a flexible duct, fixed in rotation on the first shaft, commonly a pulse shaft, such as, for example, the crankshaft of an internal combustion engine, and which supports, by its outer periphery, a cover to which at least one pressure disc is fixed. The pressure disc is coupled in rotation with the cover and with the reaction disk, being able to move axially under the exerted force of axially acting clutch means controlled by disengagement means; the clutch means may consist of helical springs, or one or two Belleville washers mounted in series or in parallel, subject to the action of disengagement levers forming the disengagement means; generally, the clutch and disengagement means belong to the same part, for example a metal diaphragm resting on the cover; The diaphragm can be mounted in series or in parallel with a Belleville washer, to give additional support to the disengagement effort. A friction disk, which carries at least one friction lining on its outer periphery, coupled in rotation with a shaft, commonly a driven shaft, such as the input shaft of the speed box, is sandwiched between the pressure disc and the reaction disk, so as to be enclosed between them when the clutch is in the coupling position. The clutch means controls the axial displacement of the pressure disc when they are actuated by a disengagement stop by intermediation of the disengagement means. Frequently, the friction disk comprises an axially elastic support disk on which two friction linings are fixed on one side and the other. The clamping of the friction disk is therefore progressive. In one embodiment, the support disc is rigid and, for example, embedded in its outer periphery within a friction lining. Throughout the useful life of a clutch of these characteristics, the friction fitting (s), as well as their countermaterials, namely, the pressure disc and the reaction disc, wear out, which causes a variation in the position of the pressure disc as well as those of the axially acting clutch means and the disengagement stop, and consequently a variation in clamping force occurs between the friction disk, on the one hand, and the pressure and pressure discs. reaction on the other, due to the modifications of the working conditions of the disengagement means, and the force necessary to realize the disengagement is therefore affected. By providing said clutch of a wear adjustment device, these drawbacks are avoided, the clutch means together with the disengagement stop, commonly in constant support on the disengagement means, occupy the same position when the clutch is in the coupling position. , So as to reduce the axial space of the clutch: A friction clutch, in particular for automotive vehicles, is known in the art, of the type comprising a reaction disk intended to be staggered in rotation on an impulse shaft. , a friction disk that carries on its outer periphery at least one friction lining, driven in rotation on a driven shaft, a pressure disc, a fixed cover on the reaction disk, axial-acting clutch means controlled by means of disengagement and working, on the one hand, between the cover and, on the other hand part, the pressure disc by intermediation of secondary and primary support means, the pressure disc is coupled in rotation with the cover, while being able to move axially with respect to itself and is subject to the action of means recoil elastics, which push back the pressure disc axially towards the cover, said clutch also comprises a device for adjusting the wear comprising means with ramps, which are arranged in circumference, placed axially between the support means and the disc of pressure, and adapted to work together with counter-trapping means, a toothed surface with which cooperates an endless screw arranged tangentially, the ramp means are coupled in rotation with the aforementioned toothed surface, means being provided for driving in rotation with the endless screw, which are activated when by the wear of the friction liner (s) during the actuation of the clutch, constituted by a ratchet wheel coupled in rotation with the endless screw, and controlled by the intermediation of a drive tab having an elastic element, the worm and the ratchet wheel are supported on a support, support and element elastic are coupled to the cover, and are placed inside the latter, the support is U-shaped and has a core and two fins adapted to support an axle carrying the worm and the ratchet wheel. A clutch of these characteristics is described, for example, in document FR-A-2 753 503. · The present invention aims to propose a friction clutch of a device for adjusting the wear of friction linings, in particular for automotive vehicle, of the type described above, whose radial as well as axial space is reduced. According to the invention, a friction clutch, in particular for an automotive vehicle, of the type comprising a reaction disk fixed in rotation on a pulse shaft, a friction disk, which carries at its outer periphery at least one gasket. friction, set in rotation on a driven shaft, a pressure disk, a fixed cover on the reaction disk, axially acting clutch means which are controlled by means of disengagement and which act, on the one hand, between the cover and, on the other hand, the pressure disc by intermediation of secondary and primary support means, the pressure disc is coupled in rotation with the cover, while being able to move axially with respect to itself and is subject to the action of elastic means of · backward movement, which make the backward movement. pressure disc axially towards the cover, said clutch also comprises a device for adjusting the wear comprising means with ramps, which are arranged in circumference, placed axially between the support means and the pressure disc, and adapted to work together with counter-trapping means, a toothed surface with which an endless tangentially co-operating screw co-operates, the ramp means are coupled in rotation with the aforementioned toothed surface, driving means being provided in rotation with the worm, which is they activate when by the wear of the friction lining (s) during the actuation of the clutch, constituted by a ratchet wheel coupled in rotation with the endless screw, and controlled by the intermediation of a drive tongue which. it has an elastic element, characterized in that the endless screw and the ratchet wheel are mounted in rotation about an axis directly carried by the cover. Advantageously, - the cover has two radially oriented fins adapted to support the axis. oriented tangentially thanks to two holes that have the fins and that the shaft goes through. Preferably, the cover has locally a radial extension outwardly, in generally U-shaped cross section with a core and said two fins. Preferably, the shaft is adapted to also support said "stop piece" adapted to receive the toothed surface in axial stop Advantageously, the stop piece comprises support wings through which it is supported by the shaft and returns directed towards the shaft. inside and towards each other and on which the toothed surface axially abuts. Preferably, the stop piece comprises a radial arm directed towards the outside and adapted to rest on the side facing the reaction disc of a rim of fixing the cover Advantageously, the toothed surface is carried by a segment having end arms by means of which it is hooked to the means of ramps, arms which are reduced, elastic and arched in such a way as to deviate the surface axially teeth that apply against the stop piece.Preferably, the elastic element has the general shape of a sheet of great length that is extends radially along a face of the bottom of the cover to which it is directly fixed. Preferably, the free end of the elastic element is in the form of a drive tongue extending generally parallel to the clutch shaft. Preferably, the part that is located radially towards the outside of the elastic element and the actuating tongue are radially in a straight line with respect to. the opening created at the bottom of the | roof. Advantageously, said part radially towards the outside of the elastic element is slightly arched, with its convex side facing towards the aforementioned opening, so that it can be axially located at. less in part in vertical with respect to the thickness of the bottom of the cover. Preferably, transverse arms extend on one side and the other of the actuating tongue and are adapted to abut against the radial edges of the opening, which constitute a control stop. Preferably, the axially acting clutch means is constituted by a diaphragm.
Preferably, the elastic element is fixed to the cover by means of one of the fastening elements of the articulation means of the diaphragm on the cover. Preferably, the ratchet wheel is driven by the diaphragm, by means of the actuation tongue. Preferably, the ratchet wheel is driven by an activator constituted by a radial appendage which presents the diaphragm on its external periphery. Preferably, the activator is offset axially towards the bottom of the cover with respect to the Belleville washer portion of the diaphragm. Preferably, the actuator is positioned axially between the back of the actuating tab and the end of an elastic leg that has the elastic element taking advantage of a trimming performed for these purposes. Preferably, the ramp means are constituted by a ring that has axially, on one side, the ramps inclined and distributed in a circle and, on the other hand, the secondary support means. Preferably, the ramps and secondary support means are located radially in a substantially straight line with each other. Preferably, the counter-ramp means consist of terminals intended to work together with the ramps of the ramp means.
Preferably, the worm is mounted so that it can move along its axis when it is subjected to the action of a resilient elastic means. Preferably, the cover comprises an annular skirt inclined on the axis, with a perforation in a straight line with respect to the worm, which is partially housed in this opening. For a better understanding of the objects of the invention, we will describe below, but not limitingly, the modalities represented in the attached drawings, in which: Figure 1 is a partial sectional view of a clutch in accordance with the invention provided with a device for adjusting the wear; Figure 2 is a view of the clutch, with partial detachment, following the direction of the arrow II illustrated in Figure 1; Figure 3 is a front view of the ramp means; Figure 4 is a perspective view illustrating the interior of the cover, once the ramp means, the worm, the ratchet wheel and the coil spring are housed; Figure 5 is a partial view of the clutch mechanism in perspective, showing a partial detachment; figures 6 to 8 illustrate the stop piece alone, where figure 6 is a plan view and figures 7 and 8 are sectional views along lines VII-VII and VIII-VIII of figure 6, respectively;
Figure 9 is a perspective view of the stop piece alone; Figure 10 is a partial side view, in perspective, illustrating the cooperation between the activator and the elastic element; Figure 11 is a plan view of the diaphragm provided with the activator; Figure 2 is an enlarged view of the amplified detail XII of Figure 11, showing the trigger. With reference to the figures, a friction clutch mechanism is observed, specifically for automotive vehicle, which includes a pressure disc 11 that works together with a friction disc 100 illustrated in figure 1, constituted by a veil or disc of support which, in this case, carries on its outer periphery friction liners 101 and which works together with a reaction disk. The reaction disk, not shown, forms part of a stationary-rotating flywheel, on a pulse shaft, for example the crankshaft of the internal combustion engine. The friction disk 100 is coupled in rotation with a driven shaft, such as the input shaft of the gearbox, by the intermediation of a hub supported by the veil on its internal periphery. The pressure disc 11 is made of a mouldable material, in this case cast iron, and - is rotatably coupled with a recessed cover 12, in a manner known in the art, by the intermediation of tangential tongues not illustrated which are axially elastic and which at the same time constitute means of readjusting the pressure disc 11 towards the cover 12, made of embossed sheet. The cover 12 includes a bottom 42, generally of transverse orientation, joined by an annular skirt 41 inclined on the axis, to a radial flange 21 for fixing with the reaction disc. This flange 21 is divided into several axially offset fields. The pressure disc 1, while it is coupled in rotation with the cover 12, is able to move axially with respect to this cover 12 under the exertion exerted by the axially acting axially driven means, and in this case the diaphragm 13. it is articulated on the cover 12 thanks to a ring-shaped crown 10 supported by rivets 48 implanted on the internal periphery of the bottom 42 of the cover 12 and by inlays 18 in the form of circular arcs created on the bottom 42 of. the cover 12, and which offer a primary support to the diaphragm 13, and the clutch is, in this case, of the push type, and the disengagement operation is therefore performed by acting on the end of the fingers of the diaphragm 13 in the direction of the arrow F illustrated in figure 1, wherein the clutch is illustrated coupled; the diaphragm 13 is mounted by articulation between the primary support 18 and the outer periphery of the crown-ring 10 which allows the diaphragm to be resiliently adjusted against the primary support 18. To maintain the axially acting elastic means 13, when the clutch is engaged, in a position independent of the wear of the liners 101 of the friction disc 100, and to a lesser extent, the wear of the pressure and reaction discs 11 whose surfaces, known as friction surfaces, wear out upon contact with the discs. garrisons 101 of the disc 100, a wear readjustment device is provided that includes ramp means 14 having ramps 16 arranged in a circle; specifically, these ramp means 14 are constituted by a ring having ramps 16 distributed in a circle on its face facing the pressure disc 11; on its opposite face, this ring has a support zone 17, or secondary support, constituted by a rounded upper edge configured as a circular arc centered on the clutch axis. Of course, this secondary support zone 17 can be continuous or discontinuous. This support 17 is implanted radially above the primary support 18. The pressure disc has, on its surface facing the bottom 42 of the cover 12, a transverse support face having counter-trapping means constituted by the counter-rails 15, in this case - in the form of terminals, distributed in a circle at a distance from each other and corresponding to the distance separating in a circle two successive ramps 16, and each of the counter rails 15 must work with - one of the ramps 16. Half ramps 14 are located axially between the diaphragm 13 and the counter-trapping means, so that the counter-rails 15 accommodate the ramps 16 and the diaphragm 13 works together with the secondary support zone 17 which thus constitutes the means of support by means of which the diaphragm 13 acts on the pressure disc 11.
The toothed surface 19 is connected to the ramp means 14 by means of rotary linking means that allow a relative axial displacement of the two parts, that is, of the toothed surface 19 with respect to the ramp means 14, as it is described in document FR-A-2 784 50. On its external periphery, the ramp means 14 have radial legs 44 which in this case are five radial legs 44; between two of these radial legs 44, a segment 45 provided with a toothed surface 19 extends in a circle; in this case, the toothed surface 19 is created by trimming an edge of the segment 45. The bearing surface of the pressure disc 11 where the terminals 15 are located, has a circular cylindrical edge 28 on the outer periphery of which they are centered the ramp means 14 having, for these objects, an annular flange of radial orientation in close contact with the edge 28. The arms at the ends of the segment 45, between which the toothed surface 19 extends, have been thinned and are elastic and arcuate, so that they can be displaced axially when fixed to the radial legs 44, in this case by rivets, the toothed surface 19 with respect to the plane of the secondary support zone 17. For considerations of. compensation, the other three radial legs 44 include a balancing segment 55 disposed in a position diametrically opposite the segment 45 provided with the toothed surface 19. The ramps 16 and the secondary support means 17 are located radially in a straight line with each other: from this In this way, the means of ramps 14, even when they are simple and of low inertia, have a great axial robustness; together with segments 45 and 55, they constitute a subset. The counter shafts 15 and the cylindrical edge 28 of the pressure disc are machined from rough protrusions made of cast iron. The wear adjusting device also includes a ratchet wheel 20 having inclined teeth and mounted so as to be rotatable about an axis 27 which in turn carries an endless thyme 23; the thread and the pitch of the worm 23 are adapted to interact with the toothed surface 19; the endless screw 23 works together with. the toothed surface 19 under the conditions described below: The shaft 27 is supported by the cover 12; specifically, the skirt 41 of the cover 12 locally has an outwardly radial extension 22, the cross section of which has a generally U-shaped configuration, with a core 24 and two parallel fins 25 and 26, which are adapted to support the axis 27 thanks to perforations that these present and that the shaft crosses. The skirt 41 has an opening 52 in a straight line with respect to the worm 23 which is partially housed within this opening 52. The shaft 27 is also adapted to support a stop piece or bracket 30 for placement in axial stop of the toothed surface 19, so that the latter is perfectly located with respect to the worm 23; for these purposes, the stop piece 30 includes, on the one hand, supporting wings 33, 34 by means of which it is supported by the axis 27 that passes through the perforations that have these support wings and, on the other hand, some returns 37 , 38 directed inwards and towards each other, and on which the toothed surface 19 axially abuts. The stop piece 30 can be seen better in FIGS. 7 to 9. The toothed surface 19 extends between the web 31 of the stop piece 30, specifically between a radial extension 53 inwards, beyond the fins 33 and 34, and the returns 37 and 38 define a fork whose teeth wedge it axially in both directions. The purpose of these arrangements is to prevent tooth decay of the toothed surface 19 from the endless thyme., which- could be caused by the important axial vibrations that affect · the toothed surface 19, consequently causing adjustment operations without a wear has occurred, if the torque is important, particularly when the clutch is linked to a double shock absorber steering wheel. The stop piece 30 also includes, beyond the fins 33 and 34, a radial arm 31 - directed towards the outside and resting on the surface of the fastening flange 21 of the cover 12 facing the reaction disk; thus, the position of the stop plate 30 is perfectly defined; The same applies, therefore, to the axial position of the toothed surface 19 in relation to the worm 23, pushed in abutment on the shoulders 37 and 38 by the arms at the ends of the segment 45. The shaft 27 is constituted by a cylindrical body which has, on one of its ends, with grooves 47 inserted under pressure in the flap 26 of the radial extension 22 for its attachment with respect to the cover 12. The perforation 43 of the other flap 25 does not open completely on the outside of the skirt 41 of the cover 12, so that, when the axis • 27 is mounted on the cover 12, it is placed in the axial position. The worm screw 23 and the ratchet wheel 20 are made, in this case, in one piece; an axial cylindrical reaming 56 allows the assembly of this piece on the axis 27; of course, the worm 23 and the ratchet wheel 20 could also be separate pieces and arranged in such a way that the worm 23 and the ratchet wheel 20 are coupled in rotation with respect to each other. An elastic element 32, in this case metallic and of little thickness, configured as a sheet of great length that has a hole 51 for its fixation to the cover 12, by fixing rivets 48 of the ring-ring 10, and the aforementioned sheet extends along the inner surface of the bottom 42 of this cover 12. The free end of the elastic element 32 has the shape of a drive tab 36 and extends, in this case, in a parallel direction to the clutch shaft; the end of the actuating tongue 36 is narrower, and its width corresponds overall to that of the teeth of the ratchet wheel 20; When the elastic element 32 and the ratchet wheel 20 are mounted on the cover 12, the actuation tab 36 elastically cooperates with a base or foot of the tooth of the ratchet wheel 20. The part which is located radially outwardly of the elastic member 32 and actuating tab 36 are in a straight line with respect to an opening 40 disposed in bottom 42 of cover 12; this part is slightly arched, with its convex side facing towards the aforementioned opening 40, so that it can be located axially at least partly vertically with respect to the thickness of the bottom 42 of the. cover 12, which allows to create better space conditions in axial direction. Because of its great length, the elastic member 32 undergoes fewer stresses caused by bending; its mass is distributed over the whole length - which extends radially, and has great elasticity; the actuating tongue 36 has a reduced mass and its movements are wide; Centrifugal effects are therefore favorable. On both sides of the actuating tab 36 transverse arms 49 and 50 adapted to abut against the radial edges of the opening 40 extend transversely, and these edges therefore limit the path to the bottom 42- of the cover 12. of the actuation tab 36 and also function as a control stop, as can be seen in figure 10 and as explained below. Around the axis 27 there is a helical compression spring 46 which constitutes an elastic means of readjustment, as described further. ahead; in this case, the spring 46 is located axially between the ratchet wheel 20 and the fin 34 of the stop piece 30. The ratchet wheel 20, the worm screw 23 and the coil spring 46 are fixed to the cover 12, the diaphragm 13 moves with respect to itself, therefore with respect to the actuation tab 36, when the clutch and clutch operations occur; the diaphragm 13 carries on its periphery a radial appendage which functions as an activator 29, illustrated in figures 1 1 and 12, and which extends radially on the outside of the part carrying the Belleville washer of the diaphragm 13, to interact with the . tongue, actuation 36 of elastic member 32, • • while axially offset to bottom 42 of the. cover- 12 with respect to this part of the Belleville washer; As can be seen in Figure 1.2, the base of activator 29 is narrower and is coupled with the part of the Belleville washer by means of rounded ones that limit the tensions of this coupling area; taking advantage of a U-shaped cut-out, the elastic element 32 has an elastic leg 39 which extends radially beyond the base of the actuating tongue 36; activator 29, illustrated in Figure 10; it is located axially between the back of the actuating tab 36 and the end of the elastic leg 39 which, at all times, rests elastically against the actuator 29, and this arrangement makes it possible to avoid possible rebounds of the actuating tab 36; the person skilled in the art will understand that, thanks to this arrangement, when an oscillation of the diaphragm 12 occurs during the re-clutch operations, it displaces the actuation tab 36 from right to left, if reference is made to FIG. 1, and, by cooperating with the teeth of the ratchet wheel 20, the end of the actuation tab 36 rotates the ratchet wheel 20 in the clockwise direction; during the disengagement, the elasticity of the elastic element 32 and the inclination of the teeth of the ratchet wheel 20 causes the actuating tongue 36 to be mounted on the teeth of the ratchet wheel, within the limits of the displacement allowed by the stop of control described above. The wear reset device just described works in the following manner. Figure 1 schematically illustrates a coupled clutch, fitted with liners 101 of the friction disc 100, and these fittings are new, and are fitted between the reaction disc, not shown, and the disc. pressure 1 1. In this position, the end of the actuating tongue 36 is located on the base of a tooth of the ratchet wheel 20. When the clutch is disengaged, the end of the fingers of the diaphragm 13 is pushed in the direction of the arrow F, moving away from the bottom 42 of the cover 12; the diaphragm 13 oscillates around the primary support 18 under the action of the elastic adjustment exerted by the ring-crown 10; during its displacement, the outer periphery of the diaphragm 13 progressively releases the pressure disc 11, and its activator 29 the actuation tab 36, respectively; the end of the actuating tongue 36 runs along the inclined ramp constituted by the tooth in whose base it was during the previous stage, and the teeth of the ratchet wheel 20 are configured in such a way that, during this disengagement trajectory of the fittings new, the end of the drive tab 36 can not be skipped; this is possible thanks to the elastic element 32, together with its actuating tongue 36, abutting against the control stop constituted by the cover 12. When the fittings wear out, as is known in FIG.
Technically, the pressure disc 11, always subjected to the axial stress of the diaphragm 13, approaches the reaction disc which is axially fixed as
The cover 12; the activator 29 of the diaphragm 13 therefore also approaches the
Reaction disk, by dragging in its movement the drive tab 36; the ratchet wheel 20 rotates about its axis in:
| · · Clockwise; this driving in rotation of the ratchet wheel 20 causes the worm 23 to also rotate on its own axis; the ramp means 14 are immobilized in rotation under the effect of the load of the diaphragm 13, and the worm 23, which meshes with the toothed surface 19, is screwed to some extent on this toothed surface 19 thus compressing the coil spring 46, so that the correct direction of the screw thread of the endless screw 23 is provided for this to occur. During the disengagement operation following the wear phase just described, the pressure disc 11 releases the liners 101 away from the latter under the action of the tangential tabs that retract towards the bottom 42 of the cover 12 to the disc of. pressure 1, as well as the ramp means 14 in contact with the diaphragm 13 through its secondary support zones 17 and with the terminals 15 through its ramps 16. The coil spring 46 pushes the worm screw 23 towards the flap 25 of radial extension 22, from which it had moved away during the wear phase, that is, from right to left with respect to figure 2; in the absence of a load of the diaphragm 13 on the ramp means 14, the only force to overcome in order to be able to rotate these ramp means 14 with respect to the pressure disc 11, is the effort of adjusting or retracting the tangential tabs.; if the load of the coil spring 46 is sufficient to counteract this force, then the spring 46 displaces the worm screw 23 which is unable to rotate, on itself due to the pressure of the actuation tongue 36, and which will push the the surface. indented 19: when turning. on themselves, the ramps 16, interacting with the terminals 15, relatively fixed, will move the pressure disc 11 away from the bottom 42 of the cover 12, thus increasing the axial distance between the working surface of the pressure disc 11 and the areas of secondary support 17 of the ramp means 14, thereby readjusting, at least in part, the displacement of the pressure disc 11 caused by the wear of the linings 101. The load of the coil spring 46 'will be in. function of the extent to which it has been compressed by the worm 23 during the wear phases, and it is understood that several clutch and clutch operations may be necessary before the game reset device is activated and enters into the readjusting phase itself, and this depends on the relative dimensioning of the parts concerned. If the wear has been sufficient so that the ratchet wheel 20 has rotated so much that the return of the actuating tongue 36, whose recoil travel is limited by the control stop, a tooth jumps, in the next operation of disengaging the actuation tab 36 will rotate the ratchet wheel 20, and the ramp means 14 that has not yet been clamped by the diaphragm 13 turn in turn and readjust the wear; at the end of the reset operation, in the engaged clutch position, the diaphragm 3, the ratchet wheel 20 and the actuation tab 36 return to the position they occupied in the figure. Of course, it is possible to replace the ring-rim 0 with small · small profiled head columns that allow adonal support in relation to the primary support 18.. In one embodiment, the serrated surface. 19 is an independent piece of ramp media. This intermediate piece presents on its internal periphery teeth that penetrate inside the cavities created on the annular flange of axial orientation that have the ramp means beyond the secondary support 17. The serrated surface, in this way, is fixed in rotation with the means of ramps 14, being able to move at the same time with respect to the latter by means of a spike-mortise type connection.