EP1224402A1

EP1224402A1 - Control device for coupling means with variable operating force moderation

Info

Publication number: EP1224402A1
Application number: EP00910905A
Authority: EP
Inventors: Jean-Louis Delevallee; Stéphane Michel; Nicolas Pelletier; Gilles Lebas; Mathieu Leclercq
Original assignee: Valeo SE
Current assignee: Valeo Embrayages SAS
Priority date: 1999-03-08
Filing date: 2000-03-08
Publication date: 2002-07-24
Also published as: WO2000053945A1; BR0008812A; FR2790806B1; FR2790806A1; DE10084336T1; DE10084336B3; KR100688352B1; KR20010104374A

Abstract

The invention concerns a control device for coupling means (1) such as for instance a clutch, a brake, a gearbox control or a speed regulator, in particular for motor vehicles, comprising motor means (2), an actuating member (3) for the coupling means, a linkage mechanism (4) arranged between the motor means (2) and the actuating means, and a force moderating arrangement (5) comprising at least a standby power storage (6) for moderating the operating force of the motor means. The invention is characterised in that the force modifying means (7) act on the power storage to vary the level of power stored therein.

Description

"Control device for coupling means with variable effort moderation".

The present invention relates to a device for controlling a coupling means, such as for example a clutch, a brake or a variable speed drive, in particular for a motor vehicle.

Such a device is described in the documents FR A 2 523 743 and FR A 2 541 793. Such a device comprises a drive means, an actuating member of the coupling means and a connecting mechanism arranged between the drive means and the actuator.

The coupling means comprises at least one output element suitable for being clamped between at least one pressure element and a reaction element, this reaction element can optionally be divided to form a torsional damping flywheel or a flexible steering wheel. The output element may consist of a disc, a clutch friction also called a friction disc, or a belt. The pressure element may consist of a pressure plate, a piston or a movable flange of a pulley. This pressure element is axially movable in both directions and is subjected to the action of at least one axially acting clamping means, such as a diaphragm, for clamping the outlet element between the pressure elements and of reaction. The clamping means and the pressure element form a movable assembly between two limit positions to modify the state of the coupling device. Thus in a clutch the output element is normally in a limit clamping position, while, on the one hand, in a brake, the output element is normally in a limit release position, and, on the other hand, in a speed variator, the belt is always tightened in its two limit positions. To do this, an opposing wheelhouse is adapted to act on the crew to move it from its first limit position to its second limit position and vice versa.

All this depends on the numerous applications and for more details, see in particular Figures 1 and 10 of document FR A 2 523 743 respectively showing an application to a clutch and to a variable speed drive with pulleys and belt.

In light of this document, it can be seen that the wheelhouse comprises at least one output element constituted by a driving element, such as a clutch release bearing mounted to slide axially on a guide tube, for action on the clamping means axial action.

In one embodiment disclosed in particular in this document FR A 2523 743 the actuating member of the control device acts directly on this driving element and consists of a clutch release lever in the form of a fork so that the opposing wheelhouse comprises only this attack element.

As a variant, the wheelhouse also includes an input element on which the actuating member of the control device is able to act. This member consists for example of a rod acting in traction or in thrust on a pivoting declutching fork itself acting on the driving element so that the wheelhouse is mechanical in nature.

Alternatively the wheelhouse may include hydraulic parts such as a liquid column or the like.

Thus in one embodiment, the actuating member, for example in the form of a rod, actuates the piston of a transmitter of a hydraulic control comprising a receiver acting on the aforementioned declutching fork or directly by its piston on the attack element as described for example in document FR A. 2 698 931 the receiver then being of the concentric type.

The wheelhouse can therefore be of any suitable nature. To automate the operation of the coupling means, it has been proposed in the documents FR A 2 523 743 and FR A 2 541 793 to provide the control device with a maneuvering effort moderating arrangement comprising at least one energy accumulator assistance to moderate the operating force of the motor means. Thanks to this arrangement, the motor means, such as a closed center hydraulic motor having a positioner effect or an electric motor, is of low power and the device for control is of simple construction and space-saving while benefiting from a sensitivity of operation comparable to that of a manual control for example with the foot using a pedal.

In addition, the output element can be slid in a controlled manner, in particular to filter vibrations or avoid blockage.

Wear occurs within the coupling means during the lifetime of the latter. For example, the friction linings of the clutch friction disc wear out, as well as to a lesser extent the friction faces of the clutch pressure and reaction plate between which the friction linings are disengageably clamped. . In a variable speed drive and in a brake the belt respectively the friction linings wear out. As a result, the position of the pressure element and therefore of the driving element vary.

The force developed by the clamping means therefore varies during the lifetime of the coupling means.

To take this into account and not to modify the coupling means, the characteristic curve (force as a function of the stroke) of the assistance energy accumulator is chosen to compensate for that of the clamping means in the middle of its duration. life as disclosed in document FR A 2 609 562 (Figure 2) in the context of a diaphragm clutch.

In addition, the dispersions due to the dispersions of the manufacturing tolerances of the constituents modify the force exerted by the clamping means.

This arrangement is satisfactory, however the applicant wondered whether it was not yet possible to better control the effort of maneuvering of the driving means as a function of the wear phenomena and of the dispersions due to the manufacturing tolerances of the constituents of the means coupling, without significantly modifying this coupling means.

The object of the present invention is to respond to this wish in a simple and economical manner. According to the invention a control device of the aforementioned type is characterized in that force modifying means act on the assistance energy accumulator to vary the level of energy stored by it.

Thanks to the invention, it is possible to vary the assistance of the force moderating arrangement as a function of wear within the coupling means so that the motor means works with better controlled power without providing for a catch-up device. wear within the coupling means as described for example in document FR A 2 599 446. The control device is thus more reliable and has a longer service life, the motor means provides less energy.

In addition, it is economically freed from the manufacturing tolerances of the parts of the kinematic chain going from the coupling means to the control device because the assistance energy accumulator can be adjusted from the start depending on the characteristic of the means. coupling.

In addition, temperature phenomena can be taken into account to vary the assistance of the moderating arrangement as a function of the temperature, knowing that when the vehicle has to travel in a cold country the torque seen by the driving means is not the same than in a hot country. It is also possible to take account of the phenomena of expansion, for example momentary swelling, under severe operating conditions, of the friction linings of a clutch resulting in a modification of the force of the clamping means. There may also be expansion phenomena caused by the heat given off by a rotating electric machine forming an alternator and starter, being associated with the clutch and leading to a modification of the force of the clamping means. Such a machine is described for example in the document FR 98 09639 filed on 07/28/1998. So we adjust at will according to different parameters

(wear, temperature, manufacturing tolerances, expansions, etc.) the assistance effort of the effort moderating arrangement.

The solution is therefore reliable, economical, with a long service life and takes account of evolving deformations, such as wear, and momentary deformations occurring in particular within the coupling means. The control sensitivity of the coupling means is improved. In light of document FR-A-2609562, the invention simplifies the strategy for controlling a clutch with motorized actuation.

To limit the stroke of the motor means without modifying the coupling means, provision is advantageously made to provide the control device with a length adjustment device to compensate for the wear of at least one component of the coupling means.

The control device thus takes account of changes in the state of the coupling means, in particular of its wear, without resorting to a wear take-up device within this coupling means.

According to one characteristic, the start-up of the force-modifying means is controlled by detection means receiving at least one piece of information coming from a variation of one or more operating parameters of the coupling means of the kinematic chain ranging from means of coupling to the control device.

The information can therefore come from at least one of the components of the coupling means. By exerrple one can detect the position of the pressure element, or the thickness of at least one of the output and reaction elements, or the force exerted by the clamping energy accumulator on one at less of its supports. According to other characteristics: the force modifying means are controlled by at least one detector means which receives information representing a variation of one or more operating parameters of the coupling means so that the control of the means d coupling is optimized; - The detector means receives information from the coupling means;

- The detector means receives information from the actuating member;

- Economically and more reliably, the detector means receives information from the drive means, so that the coupling means and its associated linkage are not modified; the operating parameter (s) depend on the wear of at least one friction material which the coupling means presents;

the operating parameter or parameters depend on the dispersions of the operating characteristics of the coupling means observed between different parts manufactured in the same series so that the control device adapts in a simple, efficient and economical manner to each of the means of 'product coupling; - The detector means uses the force supplied by the motor means as information so that one benefits directly from knowing the value to be modified;

the detector means uses a movement of the coupling means, of the actuating member, of the connection mechanism or of the motor means as information;

- The energy storage means comprises a metal spring, such as a coil spring, which represents an economical solution;

- The energy storage means comprises an element made of synthetic material or rubber, which is favorable for reducing noise;

- The energy accumulator means comprises a pressurized fluid, which makes it possible to store a greater quantity of energy and to restore it very quickly; - The force modifying means acting on the energy accumulator comprise a variable mechanical system connected to the energy accumulator, which represents an economical solution; the force modifying means acting on the energy accumulator includes a means acting on the pressure of the fluid or acting on the distribution of the fluid, which makes it possible to easily control the force exerted by this energy accumulator; the force modifying means acting on the energy accumulator have their own motorized system acting on at least one of its variable geometric characteristics; economically and reliably, the force-modifying means acting on the energy accumulator are actuated by the motor means, which thus has a double function;

- In a simple manner, the motor means acts on the force modifying means by means of an additional stroke or overtravel carried out outside the normal stroke necessary for the operation of the coupling means;

- The coupling device is not activated during the realization of an overtravel to act on the force modifying means;

- The force modifying means comprise a ratchet wheel allowing the force modifying means to have a progressive variation and always in the same direction of its variable geometric characteristic; - the overtravel carried out by the motor means varies the ratchet wheel by at least one tooth; a housing supports the force-modifying means and comprises a control finger acting on the ratchet wheel, during an operation of the coupling means, said operation comprising an overtravel;

- The force modifying means comprise a screw and nut assembly acting on the energy accumulator means; the ratchet wheel is adapted to actuate by means of a gear reduction system the screw and nut system;

- the screw and nut system comprises one of its elements, screw-nut, bearing on the spring, while the other of its elements, respectively nut-screw, is suitable for being driven by the ratchet wheel via a gear wheel and worm gear reducer;

the effort modifying means include a means for manually resetting this effort modifying means during an intervention on the coupling means, this resetting can consist of rotation of an element of the reducer or of the ratchet wheel after having neutralized the ratchet system of the ratchet wheel if necessary, this means making it possible to prepare the device for control after, for example, the exchange of at least one component of the coupling means; the force modifying means act on the assistance energy accumulator to vary the level of energy stored therein, by increasing or decreasing it alternately;

the motor means acts on the force-modifying means by means of an additional stroke made in the other direction with respect to this first additional stroke, or else by a second additional stroke which goes in the same direction but at beyond this first additional stroke, to vary the level of energy stored by the energy accumulator by increasing or decreasing it alternately, which represents an economical means of production;

- The force modifying means comprise a second ratchet wheel, which is implemented by means of an over stroke of the motor means, and which varies the energy level of the energy accumulator in the other direction than the variation provided by the first ratchet wheel, the ratio between the rotation of a ratchet wheel and the induced variation in the energy level being able to be different for one wheel or the other;

- The detector means receives information from an electric sensor detecting the travel of an element; - The drive means comprises an electric motor;

- The detector means uses as information a measurement of the electric current consumed by this electric motor, which gives precise information of the torque supplied by the motor means while not requiring additional means; - This information is given during the actuation of the coupling means during a round trip phase of this actuation, in order to measure the values of the amount of energy used by the motor means during the outward and return movements, in order to '' deduce a possible adjustment to be made on the effort-modifying means; the detector means compares different measurements made on these energy levels, in order to deduce by comparison an evolution of the coupling means and therefore act on the force-modifying means, which makes it possible to follow this evolution over time by a sampling system, by eliminating parasitic phenomena which would influence certain particular values;

the force modifying means are adjusted to keep a constant ratio between the two energy levels supplied by the motor means, during the outward and return phases of its actuation, which makes it possible to keep a certain balance between these two phases ;

- with a clutch system used as a coupling means, the energy accumulator provides more energy in the declutching phase compared to that supplied in the clutch phase, which makes it possible to obtain higher disengaging speed; the coupling means comprises a diaphragm spring for clamping the plates on at least one friction lining, said current measurement makes it possible to measure wear of the friction lining resulting in a variation in its thickness, and therefore a variation in the geometry of the diaphragm spring and the force it exerts;

- The force modifying means of the energy accumulator are used to vary the level of energy accumulation, to compensate for a change in the value of the force to be exerted on the diaphragm spring; this variation of the level of the energy accumulator is done by compressing the metal spring, to compensate for a wear of the friction lining which tends, by a modification of the operating geometry of the diaphragm spring, to increase the necessary effort to actuate the coupling means in the direction of disengagement;

- The drive means comprises a pressurized fluid producing a substantially linear movement of the connecting means;

- The electric motor is mounted with a speed reducer producing a substantially linear movement of the connecting means; - the speed reducer is constituted by an endless screw on the motor shaft, cooperating with a toothed wheel, acting on a system of the pinion and rack type to maneuver the connection means, which gives this connection means linear movement; the connection between the motor means and the energy accumulator means is a device which transmits a force in a non-linear manner, which gives a characteristic curve of the force supplied by the accumulator as a function of the displacement; - the non-linear connection system is constituted by a mechanical system of cam or articulated links, arranged in such a way that the energy storage means applies a certain force to the connection means at all times, force of a value close to that which must be provided to actuate the coupling means, which makes it possible to reduce the force which must be delivered by the motor;

- the non-linear connection system consisting of a system of articulated links includes a first link linked by a pivot with the connection means, its other end receiving a pivot linked to a second link, this second link is linked to its other end to the energy storage system, and between the two ends of this second link is a pivot linked to the casing of the force-moderating arrangement assembly, which makes it possible to produce an economical means; - the three axes of the rods are not aligned, and the non-linear system is arranged so that when the coupling means is disengaged, the two support points of the metal spring as well as the pivot are substantially aligned, this which represents a self-locking position, for the maintenance of the assembly in this position it is not necessary that the drive means produce a force which would consume energy;

- The connecting means comprises a system for adjusting its length, which makes it possible to have an operation of the motor means independent of a modification of the strokes of at least one element of the kinematic chain;

- The connecting means comprises a rod carrying teeth cooperating with one or more pinions, these pinions can be stopped in rotation by a complementary means, which represents an economic system;

- The lengthening means can be actuated by an overtravel of the motor means, which represents a simple embodiment requiring no new means;

- the overtravel of the motor means causes an action on the complementary means which bears on the housing, which leaves the pinions free to rotate the pinions;

- The control device is arranged in such a way that wear and tear on the coupling means is compensated, with regard to the travel or the force to be provided by the connecting means, so that the driving means is little influenced by this wear of the coupling means, which makes it possible to provide a dimensioning of the motor means adapted for a single operating case; - The control device comprises a control means to signal a variation of at least one parameter of the coupling means, and to know the evolution of this parameter which can be for example the wear of the friction lining; the control means gives information dependent on the actions carried out on the force-modifying means, or on the length adjustment system, which is an economical means which does not require additional devices.

The structure and the characteristics of the force modifying means as stated above correspond to a given embodiment only by way of example, knowing that other embodiments will also be envisaged.

The following descriptions illustrate the invention with reference to the accompanying drawings in which: FIGS. 1 and 2 represent a coupling means of the friction clutch type, FIG. 3 is a schematic view of the principle of a device according to the invention to control the coupling means of FIG. 1, FIGS. 4, 5 and 6 illustrate a control device according to the invention with a first embodiment of the force modifying means of the control device, FIGS. 7 and 8 illustrate a variant of the force-modifying means of FIGS. 4, 5 and 6, FIGS. 9 and 10 illustrate a means of lengthening a linkage mechanism of the control device, - FIGS. 11 and 12 illustrate a second embodiment of the force modifying means of the control device, FIGS. 13, 13a and 13b illustrate a third embodiment of the force modifying means of the control device, FIGS. 14 and 14a to 14e illustrate a different operating principle of force modifying means of the control device, FIGS. 15 and 15a to 15d illustrate a fourth embodiment of the force modifying means applying the operating principle illustrated in FIGS. 14 and 14a to 14e, and Figures 16, 16a and 16b illustrate an alternative embodiment of the fourth embodiment of the force modifying means.

In Figures 1 and 2, we see in 1 a coupling means, in 3 an actuating member of the coupling means.

The actuating member 3 belongs to a device 12 for controlling the coupling means 1. This means comprises at least one outlet element 13 suitable for being clamped between at least one pressure element 14 and a reaction element 15. This reaction element can optionally be divided to form a torsion damping flywheel or a flexible flywheel. The output element 13 consists of a clutch friction also called a friction disc. The pressure element consists of a pressure plate.

This pressure element 14 is axially movable in both directions and is subjected to the action of at least one axially acting clamping means 16, here a diaphragm, for clamping the outlet element 13 between the pressure elements and reaction.

The clamping means and the pressure element form a movable assembly between two limit positions to modify the state of the coupling device. Thus in a clutch the output element is normally in a limit position for clutch engagement engaged (FIG. 1) and in a second limit position for disengaging the clutch disengaged (FIG. 2). To do this, an antagonistic wheelhouse 17 is adapted to act on the crew to move it from its first limit position to its second limit position and vice versa.

For more details, reference will be made to the document FR A 2 523 743. For the record, it will be recalled that the clutch friction 13 has at its external periphery at least one friction lining 18 secured to a support disc 19 so connected rigid or elastic to a hub 20 internally grooved for its rotational connection to a driven shaft 21, here at the input shaft of the gearbox of the motor vehicle.

In Figures 1 and 2, two friction linings

18 are arranged on either side of the metal support disc

19 connected elastically using the springs 22 to the hub 20.

The reaction plate 15 is secured here is secured to a shaft 23 leading to the crankshaft of the vehicle engine.

The diaphragm 16 is pivotally mounted here on a cover 24 fixed on the reaction plate 15. The pressure plate 14 is linked in rotation to the cover 24 in known manner using axially elastic tongues not shown.

For more details, reference will be made to document FR-A-2456877 showing different arrangements of the diaphragm 16 pivotally on the cover. In FIGS. 1 and 2, the diaphragm 16 is pivotally mounted on the cover 24 using lugs 25 produced by cutting and folding the bottom of the cover, and a ring ring 26 as in FIGS. 1 to 4 of this document.

Here the elastic clamping force of the diaphragm 16 is such that it remains constantly in abutment against the cover 24. It will be noted that the characteristic curve of the diaphragm

16, effort as a function of deflection, has a shape overall sinusoidal and goes through a maximum as explained in this document FR-A-2456877.

This curve varies in time depending on the wear of the friction linings 18. Similarly, an increase in the thickness of the linings 18 under the effect of heat following severe conditions of use caused by an increase in the temperature of the plates 14 and 15 causes a variation in the load exerted by the diaphragm 16 on the pressure plate 14.

The load exerted by the diaphragm 16 on the plate 14 also depends on the manufacturing dispersions of the constituents of the coupling means.

The object of the present inventions is to create a control device which takes into account all these variations.

More precisely according to the invention, in FIG. 3, the control device 12 has a motor means 2, the actuating member 3, a connecting mechanism 4 arranged between the motor means 2 and the actuating member 3, a effort moderating arrangement 5 comprising at least one assistance energy accumulator 6 to moderate the maneuvering effort of the driving means 2, and effort modifying means 7 acting on the assistance energy accumulator 6 to vary the level of energy stored by said accumulator.

Here the diaphragm 16 acts on the pressure plate 14 to tighten the linings 18 between the plates 14 and 15 so that the clutch 1 and normally engaged (Figure 1).

To disengage it, the control device 12 via its actuating member 3 acts on the wheelhouse 17 to tilt the diaphragm 16 in order to cancel the load it exerts on the pressure plate 14 to release the linings 18, so that the torque is no longer transmitted between the driving shaft 23 and the driven shaft 21.

The wheelhouse 17 may have any suitable form. Here the wheelhouse 17 has a declutching fork 26 constituting the input element of the wheelhouse, and an output element 28 constituted by a declutching stop slidably mounted along a guide tube, not shown, traversed by the tree 21. The fork 27 has in known manner, at its lower end, two fingers 29 and at its upper end a semi-spherical deformation 30 for mounting a ball joint 31 secured to the rod-shaped actuating member. The fork 27 is mounted on a ball joint 32 between its ends so that it is pivotally mounted on the casing 33 of the gearbox which carries the ball joint.

Of course, the wheelhouse can include hydraulic parts and have any suitable form as mentioned above, the actuating member possibly consisting of a fork or a piston directly operating the stop 28 forming the attack element acting on the means of tightening 16.

Thanks to the control device 12, the operation of the clutch is automated as in document FR-A-2 523 743, but the driving means develop the lowest possible power thanks to the force modifying means 7 making it possible to vary the energy level stored by the energy accumulator 6 assisting the motor means.

We control the engine power better. In addition, the control device 12 (FIG. 3) comprises at least one detector means 8 which receives information from a sensor representing a variation of one or more operating parameters of the coupling means.

By variation of operating parameter is meant in particular the variations caused by wear, in particular of the linings 18, the temperature variation, the momentary variation in thickness of one of the components, for example the swelling of the friction linings 18, the variation in load of the clamping means 16, and variation in progressiveness at the level of the friction linings 18. For the record, it will be recalled that conventionally the linings 18 are mounted on either side of the support 19 while being connected to the latter of elastic way. During the clutch engagement operation, the friction linings are gradually tightened. During the life of the clutch, phenomena of inlaying of the linings occur so that the progressive tightening of the linings varies, thus generating a variation in progressiveness. This detector means 8 sends information in the event of a variation of at least one of the aforementioned parameters, to a control means 11 controlling the starting of the engine means 2. This control means 11 in the case of a clutch for a vehicle receives information concerning in particular the speeds of rotation of the shafts 21, 23, the gear ratio engaged, the position of the accelerator pedal and the position of the gear change lever. This control means 11 comprises a computer controlling the start-up of the motor means according to programs determined as a function of the information received.

The control means 11 then triggers, as a function of or information received by the detector means 8, the starting of the motor means 2 for overtraveling and actuating the force modification means in order to vary the level of energy stored in the energy accumulator.

The detection means 8 can receive information from a sensor detecting a variation in movement of the pressure element 14 of the coupling means, a variation in thickness of the output element or a variation in load of the means of Tightening. This sensor can be of the inductive, variable resistance, capacitive or pressure sensor type. This sensor may include a movable element of the friction joint, rod, pin mechanism type Mechanindus described in document FR-A-25 99 446. It is also possible to use a sensor carried by the cover of the type described in document US-A -5,238,093

It is seen from these documents 14 that the clutch may be of the pulled type (FR-A-25 99 446) or may include coil springs constituting the clamping means.

Advantageously so as not to modify the coupling means, the detection means 8 receives information from a sensor located at the wheelhouse 17. The force sensor from that of FIG. 10 of the document FR can be used as sensor. 98 09 639 deposited on July 28, 1998 when the wheelhouse comprises a piston acting on the declutching stop 28 for operating the diaphragm 16. This sensor transforms or not the information of force exerted on the declutching stop into relative information to determine the position of the stopper 28. You can use a sensor carried by the clutch release bearing such as that described in FIGS. 3 and 4 of document FR-A-26 06 428 in order to deduce therefrom, thanks to the conical splines or to missing splines, the wear of the friction linings. Preferably so as not to modify the coupling means 1 and the actuating member 3, the detector means 8 receives information from the control device 12. It can receive information from the sensor of the type described in the document FR-A-26 10 263 with a rack 39 belonging to one of the ends of a slide 40, carrying at its other end a yoke 41 on which is hingedly mounted the end of a rod 3 constituting here the actuator acting on the declutching fork 27.

The slide 40 has a blind slot 42 traversed at its bottom by a hinge pin 43 used for mounting a connecting rod 44 penetrating into the blind slot 42 being for this purpose bent at its end for mounting at articulation on the axis 43 of the slide 40 detecting the stroke of the motor means 2. Advantageously, the motor means 2 itself is used.

In fact, this motor means 2 corresponds in the embodiment of FIG. 4 to an electric motor 34, the supply terminals of which are connected to the control means 11.

The output shaft 35 of this motor is threaded to form an endless screw 36 engaging with a tangent gear 37. The drive means 2 thus form a gear motor connected to the link mechanism 4.

The input element of the connection mechanism 4 is constituted by a pinion 38 which engages the rack 39. The rod 44 extends mainly parallel to the slide 40 in FIG. 5 while being located radially below that -this . The link 44 is directed axially towards the rod 3 in the direction opposite to the rack 39. The other end of the link 44 is hingedly mounted on an axis 45 projecting from a first end 46 of a bent link 47 whose second end 48 is shaped to receive an axis 49 belonging to the force modifying means 7 according to the invention. Between these two ends 46 and 48, offset axially with respect to each other because the link 47 is bent, the link 47 is hingedly mounted on the bottom 50 of a housing 51. inside this box that the reduction gear 35, 36, the force moderating arrangement 5, the connection mechanism 4, the force modifying means 7 and in part the actuating member which crosses the transverse wall are mounted 52 of the housing 51.

This housing has a slide 53 for translational guidance of the slide 40 thus axially penetrating into a blind cavity delimited by the bottom 50 of the housing and the slide 53. In FIG. 4 we see at 54 a fan washer serving to block the end of the pinion 38 passing through the wheel 37 here in synthetic material, such as plastic, knowing that the pinion 38 is here metallic as well as the slide 40 and the shaft 35.

Note that the second end 48 of the link 47 generally consists of a blind hole washer for receiving the axis 49. This washer 48 is hinged on an axis 148 carried by the rod 47. The axis of the pivot 148 extends protruding.

The angled link 47 is hingedly mounted on the bottom 50 of the housing 51 by means of a pivot 62 carried by the link 47 and engaged in a hole in the bottom 50. Of course, the structures can be reversed, the pivot 62 being able to be carried by the bottom 50. This pivot 62 extends projecting.

Thus the links 44, 47 belong to a non-linear transmission system 9 (FIG. 3) intervening between the force-modifying means 7 and a connection mechanism of the linear type 4 connected, on the one hand, to the control member. 3 and, on the other hand, to the reduction system 36, 37 of the motor means 2 with worm screw 36 and toothed wheel 37. This reduction system 36, 37 is economical and reliable.

The pinion 38 constitutes the input element of the connection mechanism 4, the output element of which is constituted by the control member 3 forming the output element of the control device. The top of the slide 53, here of trapezoidal shape, is provided with a longitudinal slot so that the pinion 38 comes into engagement with the rack 39. Thus one obtains, thanks to the geared motor, forming the motor hub 2, an economical solution, without risk of jamming of the rack 39, reliable and of great duration of life because wear is reduced.

The actuator 3 constitutes the output element of the control device 12 and of the link mechanism 4 of the linear type.

The links 44, 47 constitute the non-linear system or device 9 of FIG. 3, acting between the force-modifying means 7 according to the invention and the connection mechanism 4. These links 44, 47 comprise four axes or pivots 43, 45, 62, 148, the mechanism 4 and the means 7. Only the axis 62 is fixed, the other axes being movable with the parts to which they are attached.

The second end 48 has a blind hole for receiving the axis 49 belonging to the force moderating means 5 varying the energy stored by the accumulator 6 here comprising a metal coil spring 55 working in compression.

Of course the accumulator can alternatively comprise two concentric coil springs or Belleville washers mounted in series. The accumulator 6 therefore therefore comprises here at least one metal spring. As a variant, this spring can be made of elastic material such as elastomer. Of course, this spring of elastic material can be associated with a metal spring.

As a variant, the spring 55 may belong to a hydraulic damper and intervene between the piston and a support belonging to a cylinder. The support is located on the opposite side from the bottom of the cylinder and is crossed with sealing by a piston rod connected to the force-modifying means 7.

The piston, for example in the form of a washer, is pierced for passage of the fluid, while the spring bears on the piston and on the support of the cylinder, for example in the form of a washer traversed by the rod. As a variant, the energy accumulator 6 is of the hydraulic or pneumatic type. The accumulator can therefore have any suitable shape.

In FIGS. 4 and 5, the coil spring 55 is mounted in a blind cylinder 63, the bottom of which has an articulation head 64 in the form of a semi-cylindrical projection engaged in a complementary recess 65 produced in the housing 51 closed by a cover not visible in figure 4.

In FIG. 5, the skirt of the cylinder 63 has not been shown to show the spring 55 and the force modifying means 7 have been shown diagrammatically.

Thus, the cylinder 63 is hingedly mounted on the housing 51, its head 64 nesting hingedly in the complementary recess 65. The cylinder 63 can therefore move angularly and, for this reason, the housing 51 has a protuberance 66 of the side opposite the motor means to allow angular movement of the cylinder 63.

The effort moderating arrangement 5 therefore corrects the connection 4, the non-linear system 9 with links 44, 47, the effort modifying means 7 and the energy accumulator 6 arranged on several stages (FIG. 4) to reduce thickness of actuator

12.

This actuator 12 has three stages, namely, a first stage with the shaft 35, a second stage comprising the rack 4 parallel to the shaft 35 and a third stage comprising the cylinder 63 and the spring 55. This third stage is inclined relative to the other two stages and is connected to the second stage by means of the non-linear system 9 with links 44, 47. The second stage is connected to the first stage by means of the reduction system 36, 37.

The actuator is thus compact and makes it possible to reproduce very faithfully the characteristic curve of the diaphragm 16 which comprises a peripheral part in the shape of a Belleville washer extended radially towards the center by a central part fragmented into radial fingers by slots.

We obtain a better reproduction of the characteristic curve of the diaphragm, visible in particular in the document FR-A-2609 562 that with the force moderating arrangement described in the document FR-A-2541793 and this, with reduced wear due to the presence of the rack 39 and the axes or pivots 43, 45, 62, 148. Only the pivot 62 is associated with a fixed part. The movements are therefore of small amplitude and the risks of jamming reduced due to the presence of the slide 40, with a trapezoidal apex (FIG. 5) sliding in its complementary slide.

The arrangement 5 therefore acts on the wheel 37 and has a characteristic curve reproducing as closely as possible the curve of the diaphragm 16 so that the motor means 2 work in the best conditions.

The arrangement 5 can be devoid of the modifying means 7 and can already provide an improvement in operation on its own.

Of course, the diaphragm can be replaced by a Belleville washer acting on release levers.

The control device 12 is very compact. With the force-modifying means 7, account is also taken of modifications of the operating parameters such as wear, expansion, swelling of the coupling means.

The means 7, in addition to the axis 49, include a finger 57, forming a pawl, a ratchet wheel 56 with inclined teeth, a screw 58, a nut 59 and a reduction system 60 between the ratchet wheel 56 and the screw system - nut.

The finger 57 is fixed at one of its ends, here by riveting as visible in FIG. 4, on the housing 51 and acts by the other of its ends on a tooth of the ratchet wheel 56. The ratchet wheel 56 is extended by an axis engaged in a groove of a wheel 67. The axis of the wheel 56 extends tangentially with respect to the groove of the wheel 67.

The axis of the wheel 56 has a worm-type toothing and the toothed groove of the wheel 67 form the reduction system 60. The cylinder 63 has at least two longitudinal grooves (not referenced in FIG. 4), in each which engages a finger secured to the nut 59 so that this can only move axially. The number of grooves and fingers depends on the applications, their distribution being preferably regular.

The grooves are made at the free end of the cylinder 63. The spring 55 bears on the bottom of the cylinder 63 and on the nut 59 so that it works in compression. The axle 49, the wheel 67 and the screw 58 belong to a single piece.

As will be understood, by rotating the ratchet wheel 56, the wheel 67 and the screw 58 are rotated, which causes a longitudinal displacement of the nut 59 inside the cylinder and therefore a modification of the energy stored by the energy accumulator spring 55.

It is the finger or pawl 57 which rotates the ratchet wheel 56 by jumping from one tooth to another. The finger 57 is a control finger.

To do this, an over travel of the motor means 2 is carried out, under the control of the detector means 8 which has recorded a modification of at least one operating parameter of the coupling means 1.

This overtravel therefore leads to an overtravel of the non-linear system 9, here from the left to the right of FIG. 4, allowing the finger 57 to jump at least one tooth from the wheel 56 and after cancellation of the overtravel to rotate the wheel 56 and the nut 59 to modify the load exerted by the spring 55.

Preferably, a predetermined current difference is detected in the motor means 2 between its outward stroke to pass from a first limit position to its second limit position and its return stroke, to pass from its second limit position to its first limit position.

As will be understood, the control 11 and detection 8 means belong to an electronic control unit located in the control device 12.

It is also possible to provide a second pawl 68 and a second ratchet wheel 69, as shown in FIGS. 7 and

8. There is a certain distance between the positions allowing the first pawl and the second pawl to play, so as to that, by the maneuver of the engine, one can command a first overtravel to operate the force modification in one direction, then going beyond by a second additional overtravel, one can operate the modification in the other way. Thus, by successive maneuvers, one can at will modify the energy level in both directions.

FIGS. 9 and 10 show a device for lengthening the connecting means 4.

The end of the actuating member 3 is linked to a rod having teeth. These teeth are in engagement with one or more pinions 70, two are shown in these figures. These pinions are carried by a support 73, linked to the end of the slide 40, and which therefore moves axially with it.

The pinions 70 are blocked in rotation by a blocking lever comprising teeth engaged with complementary teeth of the pinions. These levers can be mounted either pivoting 71 or sliding 72. These levers are returned to the pinion blocking position 70 by a spring 74.

To control a lengthening of the actuating member 3 relative to the connecting means 4, an overshoot of the connecting means is carried out, to the right in the case of the drawings, so that the locking lever 71 or 72 comes into contact with a finger linked to the housing 51, shown here in contact with the levers. In this way, the spring 74 is compressed, and the levers release the pinions, which can rotate, which allows the axis 3 to operate an axial displacement.

By choosing a rest position of the coupling means for carrying out this maneuver, and a determined position of the corresponding connection means, the system will be able to automatically cut it to length.

Another characteristic of the invention is to provide an arrangement of the rods 44 and 47, and their axes, so that, in a given position, the axis of the spring 55 is aligned with the pivot 62 (position not shown ).

In this way, the energy accumulator 6, acting through a lever of zero value, no longer acts on the connection mechanism 4. The motor 34 must not therefore deliver any force to maintain this position, it does not consume energy, and does not heat up.

This position is used preferentially in the case of a clutch mechanism, for the disengaged mechanism position because it is a position which can be maintained for a fairly long time, and in this case the diaphragm exerts a certain force of reminder that we must counter.

According to the first embodiment of the force-modifying means 7 previously described with reference to FIGS. 4 to 6, a reduction system 60 with a toothed wheel and worm is inserted between the ratchet wheel 56 and the screw-nut system 58 and 59.

According to a second embodiment of the force modifying means 7 which is illustrated in FIGS. 11 and 12, the reduction system 60 is replaced by a system with bevel wheels.

More specifically, a first bevel wheel 80 is mounted coaxially integral with the ratchet wheel 56 and rotates a second bevel wheel 82 disposed at 90 ° and which is integral with the screw 58 on which is mounted the nut 59 movable in translation but fixed in rotation and which is supported on one end of the spring 55.

Thus, by controlling an overtravel of the motor means 2 under the control of the detector means 8 which has recorded a modification of at least one operating parameter of the coupling means 1, the non-linear system 9 with its links 44 and 47 also performs overtravel (from left to right in FIGS. 11 and 12) by pivoting around the pivot 62, which has the effect of bringing the ratchet wheel 56 closer to a set of fixed pawls 84 located in the bottom 50 of the housing 51. When contact is established with the pawls 84, the ratchet wheel 56 is rotated, which also has the effect of rotating the two bevel wheels 80 and 82 and displacing the nut 59 in translation. along the screw 58 to compress the spring 55 which constitutes the energy accumulator 6 in this embodiment. According to a third embodiment of the force modifying means 7, which are illustrated in FIGS. 13, 13a and 13b, the screw-nut system 58 and 59, as well as the ratchet wheel 36, have been eliminated from the two modes of previous achievements. More specifically, the force modifying means 7 generally comprise two assemblies 86 and 88 which are axially aligned and movable in translation in two opposite directions. The first assembly 86 is mounted articulated on the link 47, and it is extended by a rod 90 which penetrates inside the spring 55 which constitutes the energy accumulator 6 in this embodiment. A lever 92 is pivotally mounted on the first assembly 86, and it comprises a finger 94 which is engaged with a tooth of a rack 96 carried by the second assembly 88. This second assembly 88 comprises a part forming a socket 98 on the opposite side to the rack 96 and in which the rod 90 is housed with the interposition of a ring 100. This ring 100 has a series of tabs 102 projecting from its internal wall and which are housed in notches forming notches 104 machined in the rod 90. The orientation of the tongues 102 is such that the two assemblies 86 and 88 can only deviate from one another.

By controlling an overtravel of the motor means 2 under the control of the detector means 8, the lever 92 comes into contact with a fixed stop 106 carried by the bottom 50 of the housing 51. The lever 92 pivots and its finger 94 pushes the rack 96, which has the effect of separating the two assemblies 86 and 88 from one another by compressing the spring 55 and this, in an irreversible manner in this embodiment.

In general, all of the force-modifying means 7 described above, except in the embodiment described in FIGS. 6 and 7, have the drawback of requiring external intervention in order to restore the energy accumulator. 6 in its initial state, when changing the coupling means 1 for example. The reliability and irreversibility of these force modifying means 7 can also pose a problem when they are subjected to significant vibrations. To this end, to compensate for these drawbacks, it is then advantageously possible to replace the screw-nut system 58 and 59 of the force-modifying means 7 of the first and second previous embodiments, by a reset system comprising, for example, two rairps. helical toothed 110 and 112 having complementary shapes and which are respectively carried by a first sleeve 114 movable in rotation and by a second sleeve 116 movable in translation.

More specifically, with reference to FIG. 14, the helical rasp 110 with its teeth 111 is machined at one end face of the sleeve 114, the other end of which carries a ratchet wheel 56 coaxial and integral with the sleeve 114. The helical ramp 112 with its teeth 113 is machined at one end face of the sleeve 116. The two sleeves 114 and 116 are mounted axially with their toothed helical ramps 110 and 112 which fit into one another by their teeth 111 and 113.

According to the developed view of FIG. 14a, each tooth

111 of the helical rasp 110 has a first slope which forms a level 111a and a second steeper slope which forms a notch 111b. Finally, a so-called return slope 111c connects the first and last teeth 111. It is the same for each tooth 113 of the helical ramp 112 which has a bearing 113a and a notch 113b, with a return slope 113c which connects the first and last teeth 113. The return slopes 111c and 113c of the helical wheels 110 and 112 form means which allow the system to be reset, as will be explained below.

The operating principle of these two helical ramps 110 and 112 is explained below with reference to FIGS. 14a and 14e.

In FIG. 14a, the two helical ramps 110 and

112 are in a position which corresponds to an initial adjustment with the two sleeves 114 and 116 separated from each other by a minimum distance. As a result of the rotation of the ratchet wheel 56 and therefore of the sleeve 114 (FIG. 14b), the teeth 111 and 113 of the two helical ramps 110 and 112 slide one over the other, which causes an axial displacement of the sleeve 116 which thus departs from the sleeve 114 due to the slopes of the bearings 111a and 113a of their respective teeth 111 and 11. When the teeth 111 and 113 have shifted by one position (FIG. 14c), the sleeve 116 has deviated by a pitch which corresponds to a minimum adjustment, and any return movement of the sleeve 116 is prevented by the cooperation of the notches 111b and 113b if the rotation of the ratchet wheel 56 is stopped.

After several successive steps and when a rreximum offset is reached between the teeth 111 and 113 (FIG. 14d), the sleeve 116 returns to its initial position (FIG. 14e) as a result of the cooperation between the two return slopes 111c and 113c teeth 111 and 113.

In FIGS. 15 and 15a, a fourth embodiment of the force-modifying means 7 has been illustrated which uses the two helical ramps 110 and 112 described above.

The assembly of the two sleeves 114 and 116 of FIG. 14 is mounted on a rod 125, one end of which is pivotally mounted about an articulation axis 127 of the link 47 of the non-linear connection system 9 which is mounted between the motor means 1 and the energy accumulator 6 constituted by a spring 55 in this embodiment. The other end of the rod 125 slides inside a tubular element 129 pivotally mounted at 131 on the housing 51. The sleeve 114, on the side of the ratchet wheel 56, bears against a shoulder 133 of the rod 125 and is rotatably mounted around this rod 125.

On the other hand, the sleeve 116 is movable in translation but fixed in rotation. To this end, the rod 125 has a non-circular cross section to prevent the sleeve 116 from rotating. The sleeve 116, towards its end adjacent to the sleeve 114, has a radially external flange 135 against which one end of the spring 55 abuts. The other end of the spring 55 comes to bear on a radially external flange 137 which is located at the end of the tubular element 129 which is articulated to the housing 51. The force modifying means 7 are actuated by a lever 140, one end of which is mounted on the articulation axis 127 between the link 47 and the rod 125. The other end of the lever 140 is bent so as to form a finger 141 intended to come into contact with the teeth of the ratchet wheel 56 and drive it in rotation. The lever 140 is attached to the link 47 and fixed to the latter by means of a rivet 142 for example.

In FIG. 15a, the force modifying means 7 are shown in a position corresponding to the engaged position of the coupling means 1. The link 47 of the non-linear connection system 9 extends substantially in the extension of the rod 125 In FIG. 15b, the force modifying means 7 are shown in a position corresponding to the disengaged position of the coupling means 1. The link 47 has pivoted around its pivot 62 and forms an angle of the order of 90 ° with the rod 125, which has the effect of positioning the finger 141 of the lever 140 in the immediate vicinity of the teeth of the ratchet wheel 56.

If an overtravel of the motor means 2 is controlled under the control of the detector means 8, as illustrated in FIG. 15c, the finger 141 of the lever 140 rotates the ratchet wheel 56, which has the effect of causing rotation of the sleeve 114 which causes, by the cooperation of the helical ramps 110 and 112, the axial displacement of the sleeve 116, as has been explained previously with reference to FIG. 14. According to a variant of this fourth embodiment of the modifying means 7 which are illustrated in FIGS. 16, 16a and 16b, the lever 140 which actuates the ratchet wheel 56 is no longer carried by a link 47, but is mounted on the bottom 50 of the housing 51. More specifically, the lever 140 is bent and mounted pivoting around a pivot 145 located at the elbow of the lever 140. An end portion 140a of the lever 140 follows a shape complementary to that of the rod 47, while its other end portion forms a finger 141. The lever 140 is held in an initial position by means of a spring 147 fixed in the bottom 50 of the housing 51. In FIG. 16, the force modifying means 7 are shown in a position corresponding to the engaged position of the coupling means 1, and the lever 140 is completely disengaged from the link 47. In FIG. 16a, the modifying means d 'effort are shown in a position corresponding to the disengaged position of the coupling means 1, after pivoting of the link 47 around its pivot 62 and which has moved closer to the lever 140 so that the link 47 comes substantially into contact of the end portion 140a of the lever 140, while the finger 141 of the lever 140 is in the immediate vicinity of the teeth of the ratchet wheel 56.

If an overtravel of the motor means 2 is controlled under the control of the detector means 8, the link rod 47 pivots the lever 140 about its pivot 145 and the finger 141 of the lever 140 rotates the ratchet wheel 56, which has the effect of rotating the sleeve 114 which causes, by the cooperation of the helical ramps 110 and 112, the axial displacement of the sleeve 116, as explained previously in FIG. 14. In general, all the modifying means force 7 described above act when the compensation spring 55 is relaxed in order to minimize the force necessary to compress it.

Claims

1. Device for controlling a coupling means (1), such as for example a clutch, a brake, a gearbox control or a speed variator, in particular for a motor vehicle, comprising a driving means (2 ), an actuating member (3) of the coupling means, a connecting mechanism

(4) arranged between the motor means (2) and the actuating member, and a force moderating arrangement (5) comprising at least one assistance energy accumulator (6) to moderate the maneuvering force motor means, characterized in that force modifying means (7) act on the assistance energy accumulator (6) to vary the level of energy stored by it.

2. Device according to claim 1, characterized in that the force modifying means (7) are controlled by at least one detector means (8) which receives information representing a variation of one or more operating parameters of the means coupling (1).

3. Device according to claim 2, characterized in that this detector means (8) receives information from the coupling means (1).

4. Device according to claim 2, characterized in that this detector means (8) receives information from the actuating member (3).

5. Device according to claim 2, characterized in that this detector means (8) receives information from the motor means (2).

6. Device according to claim 2, characterized in that the operating parameter or parameters depend on the wear of at least one friction material that has the coupling means (1).

7. Device according to claim 2, characterized in that the operating parameter or parameters depend on the dispersions of the operating characteristics of the means coupling (1) found between different parts manufactured in the same series.

8. Device according to claim 2, characterized in that the detector means (8) uses the force supplied by the motor means (2) as information.

9. Device according to claim 2, characterized in that the detector means (8) uses a movement of the coupling means (1), of the actuating member (3), of the connection mechanism (4) or of the motor means (2) as information.

10. Device according to any one of claims 1 to 9, characterized in that the energy storage means (6) corrects a metal spring such as a coil spring (55).

11. Device according to any one of claims 1 to 10, characterized in that the energy storage means (6) comprises an element made of synthetic material or rubber.

12. Device according to any one of claims 1 to 9, characterized in that the energy storage means (6) corrects a fluid under pressure.

13. Device according to any one of the preceding claims, characterized in that the force modifying means (7) acting on the energy accumulator (6) comprise a variable mechanical system connected to one energy accumulator.

14. Device according to claim 12, characterized in that the force modifying means (7) acting on the energy accumulator (6) comprise means acting on the pressure of the fluid or acting on the distribution of the fluid.

15. Device according to any one of the preceding claims, characterized in that the force-modifying means (7) acting on the energy accumulator (6) have their own motorized system acting on at least one of its characteristics variable geometric.

16. Device according to any one of claims 1 to 14, characterized in that the means force modifiers (7) acting on the energy accumulator (6) are actuated by the motor means (2).

17. Device according to claim 16, characterized in that the motor means (2) acts on the force-modifying means (7) by means of an additional or overtravel stroke carried out outside the necessary normal stroke. for operating the coupling means (1).

18. Device according to claim 17, characterized in that the coupling device (1) is not activated during the production of an overtravel to act on the force modifying means (7).

19. Device according to any one of the preceding claims, characterized in that the force modifying means (7) comprise a ratchet wheel (56) allowing the force modifying means (7) to have a progressive variation and always in the same direction of their variable geometric characteristic.

20. Device according to claim 19, characterized in that the overtravel produced by the motor means (2) causes the ratchet wheel (56) to vary by at least one tooth.

21. Device according to claim 20, characterized in that a housing (51) supports the force modifying means (7) and comprises a control finger (57) acting on the ratchet wheel (56), during a operation of the coupling means (1), said operation supporting an overtravel

22. Device according to any one of the preceding claims, characterized in that the force-modifying means (7) comprise a screw and nut assembly (58, 59) acting on the energy storage means (6).

23. Device according to claim 22, characterized in that the ratchet wheel (56) is suitable for actuating the screw and nut system (58,59) by means of a movement reduction system (60).

24. Device according to claim 23, characterized in that the screw and nut system (58,59) comprises one of its screw or nut elements bearing on the energy accumulator (6), while the other of its elements, nut or screw, is suitable to be driven by the ratchet wheel (56) by means of a gear wheel and worm gear forming the reduction system (60).

25. Device according to claim 23, characterized in that the movement reduction system is constituted by a bevel wheel system (80,82).

26. Device according to claim 25, characterized in that the system comprises a first bevel wheel (80) mounted coaxially and integral with the ratchet wheel (56), and a second bevel wheel (82) disposed at 90 °, driven in rotation by the first bevel wheel (80) and which is carried by the screw (58) of the screw-nut system (58,59).

27. Device according to any one of claims 16 to 26, characterized in that the force modifying means (7) comprise means for operating a manual reset to the initial state of these force modifying means during intervention on the coupling means (1).

28. Device according to any one of the preceding claims, characterized in that the force modifying means (7) act on the assistance energy accumulator (6) to vary the level of energy stored by that here, by increasing or decreasing it alternately.

29. Device according to claim 28, characterized in that the motor means (2) acts on the force modifying means (7) by means of an additional stroke carried out in the other direction relative to this first stroke additional, or by a second additional stroke which goes in the same direction but beyond this first additional stroke, to vary the level of energy stored by the energy accumulator (6) by increasing or increasing it alternately decreasing.

30. Device according to claim 29, characterized in that the force modifying means (7) comprise a second ratchet wheel (61), which is implemented by means of an overtravel of the motor means (2), and which varies the energy level of the energy accumulator (6) in the other direction than the variation provided by the first ratchet wheel (56).

31. Device according to any one of claims 1 to 18, characterized in that the force modifying means (7) comprise two assemblies (86,88) which are movable in translation in two opposite directions under the control of a lever (92) pivotally mounted on the first assembly (86) and which comprises a finger (94) which is engaged with a tooth of a rack (96) carried by the second assembly (88).

32. Device according to claim 31, characterized in that a fixed stop (106) mounted on the housing (51) serves as a means for controlling the pivoting of the lever (92).

33. Device according to claim 31 or 32, characterized in that the second assembly (88) bears on one end of the energy accumulator (6).

34. Device according to any one of claims 31 to 33, characterized in that the second set

(88) carries a ring (100) in which engages a rod (90) integral with the first assembly (86), and in that the ring (100) carries tongues (102) on its internal wall which engage with notches (104) machined in the rod (90).

35. Device according to any one of claims 1 to 18, characterized in that the force modifying means (7) comprise a device for resetting to zero after a certain number of adjustments of the energy level stored by the accumulator (6).

36. Device according to claim 35, characterized in that the force modifying means (7) comprise two toothed helical ramps (110, 112) which come into engagement with one another and which are respectively machined on the two faces of adjacent ends of two sleeves (114,116) axially aligned and mounted on a rod (125), one of the sleeves (114) being movable in rotation while the other sleeve (116) is movable in translation.

37. Device according to claim 36, characterized in that the teeth (111,113) of the two helical ramps (110,112) cooperate so as to separate the sleeve (116) from the sleeve (114) during the rotation of the latter.

38. Device according to claim 37, characterized in that the teeth (111,113) forming bearings (111a, 113a) and notches (111b, 113b) successive, and include a return slope (111c, 113c) to bring back the sleeve (116) against the sleeve (114) after the maximum possible offset between the teeth (111,113) of the two ramps (110,112), said return slopes forming the reset device.

39. Device according to any one of claims 36 to 38, characterized in that the sleeve (114) is controlled in rotation by a lever (140).

40. Device according to claim 39, characterized in that the lever (140) is carried by a return link (47) of the system (9) of non-linear connection mounted between the driving means (2) and the modifying means of force (7), and intended to cooperate with the teeth of a ratchet wheel (56) carried by the sleeve (114) to drive it in rotation.

41. Device according to claim 40, characterized in that the lever (40) is pivotally mounted around a pivot (145) supported by the housing (51).

42. Device according to claim 41, characterized in that the lever (140) is bent and has a first end part (140a) which matches the shape complementary to that of a return link (47) of the system (9 ) non-linear connection mounted between the motor means (2) and the force modifying means (7), and a second end part which forms a finger (141) intended to come to cooperate with the teeth of a wheel to ratchet (56) carried by the sleeve (114) movable in rotation.

43. Device according to claim 42, characterized in that the link (47) comes into contact with the end part (140a) of the lever (140) to pivot it around its pivot (145) and engage the finger (141) with the teeth of the ratchet wheel (56).

44. Device according to claims 3 or 4, characterized in that the detector means (8) receives information from an electrical sensor detecting the travel of an element.

45. Device according to any one of claims 1 to 44, characterized in that the motor means (2) comprises an electric motor (34).

46. Device according to claim 41, characterized in that the detector means (8) uses as information a measurement of the electric current consumed by this electric motor (34).

47. Device according to claim 2, characterized in that this information is produced during the actuation of the coupling means (1) during a round trip phase of this actuation.

48. Device according to claim 47, characterized in that the detector means (8) compares different measurements made on these energy levels, for by comparison to deduce therefrom an evolution of the coupling means (1) and therefore act on the means of effort modification.

49. Device according to claim 47 or 48, characterized in that the force modifying means are adjusted to keep a constant relationship between the two energy levels supplied by the motor means (2), during the outward and return phases of its actuation.

50. Device according to claim 49, in which the coupling means (1) consists of a clutch, characterized in that the energy accumulator (6) supplies more energy in the declutching phase compared to that supplied in the clutch phase.

51. Device according to claim 46, in which the coupling means (1) comprises a diaphragm spring (16) for clamping plates (14 and 15) on at least one friction lining (18), characterized in that that said measurement of the current makes it possible to measure a wear of the friction lining causing a variation of its thickness, and therefore a variation of the geometry of the diaphragm spring and of the force which it exerts.

52. Device according to claim 51, characterized in that the force modifying means (7) of the energy accumulator (6) vary the level of energy accumulation, to compensate for a modification of the value of the force to be exerted on the diaphragm spring (16).

53. Device according to claim 52, characterized in that this variation in the level of the energy accumulator (6) is done by compressing the metal spring (55), to compensate for wear of the friction lining (18).

54. Device according to any one of claims 1 to 44, characterized in that the motor means (2) corrects a pressurized fluid producing a substantially linear movement of the connecting means (4).

55. Device according to claim 46, characterized in that the electric motor (34) is mounted with a speed reducer (36,37) producing a substantially linear movement of the connecting means (4).

56. Device according to claim 55, characterized in that the speed reducer (36,37) consists of an endless screw (36) on the motor shaft, cooperating with a toothed wheel (37), which acts on in turn on a rack and pinion type system (38, 39) for operating the connecting means (4).

57. Device according to any one of the preceding claims, characterized in that the connection between the motor means (1) and the energy accumulator (6) is a system (9) which transmits a force in a non-linear manner.

58. Device according to claim 57, characterized in that the non-linear connection system (9) consists of a mechanical system of cam or articulated rods (44,47), arranged so that the accumulator of energy (6) applies a certain force to the connection means (4) at all times, a force close to that which must be supplied to actuate the coupling means (1).

59. Device according to any one of claims 54 to 58, characterized in that the non-linear connection system (9) constituted by a system of articulated links comprises a first link (44) linked by a pivot

(43) with the connecting means (4), its other end receiving a pivot (45) linked to a second link (47), this second link is linked at its other end to the energy accumulator

(6), and between the two ends of this second link is finds a pivot (62) linked to the casing (51) of the force moderating arrangement assembly (5).

60. Device according to claim 59, characterized in that the three axes (45,49,62) of the link are not aligned, and that the non-linear system (9) is arranged so that when the means d coupling (1) is disengaged, the two support points (49,64) of the metal spring (49,64) and the pivot (62) are substantially aligned.

61. Device according to any one of the preceding claims, characterized in that the connecting means (4) comprises a system for adjusting (10) its length.

62. Device according to claim 61, characterized in that the connecting means (4) comprises a rod (68) carrying teeth cooperating with one or more pinions (69), these pinions being able to be stopped in rotation by complementary means ( 70).

63. Device according to claim 61 or 62, characterized in that the adjustment system (10) can be actuated by an overtravel of the motor means (2).

64. Device according to claim 62 or 63, characterized in that the overtravel of the motor means causes an action on the complementary means (70) which bears on the housing (5), which leaves the pinions (70) free to rotate .

65. Device according to claim 61 and any one of the preceding claims, characterized in that the control device 12 is arranged so that wear and tear of the coupling means (1) is compensated, as regards the stroke or the effort to be provided by the connecting means (4), so that the driving means (2) is little influenced by this wear of the coupling means.

66. Device according to any one of the preceding claims, characterized in that the control device (12) has control means (11) for signaling a variation of a parameter of the coupling means (1).

67. Device according to claim 66, characterized in that the control means (11) gives information dependent on the actions carried out on the force modifying means (7), or on the length adjustment system (10).