FR2896555A1 - Motor vehicle clutch actuator for displacing clutch stop, has connection formed of winder and coupler and decoupling spring from motor during power supply to actuator, where motor and actuation finger are in permanent kinematic connection - Google Patents

Abstract

The actuator has an elastic return device (5) including a spring and a connection formed by a winder and a coupler for coupling the spring to a driving motor (1). The connection decouples the spring from the motor in presence of power supply to the actuator. A blocking unit formed of an electro-magnet (25) retains energy accumulated in the spring as long as the power is supplied to the actuator and liberates and applies the energy to an actuation finger (4) during power failure to displace the finger to a safety position, where the finger and the motor are in permanent kinematic connection.

Description

Actuator, particularly for a motor vehicle clutch

  The present invention relates to an actuator, in particular for a motor vehicle clutch.

  In such an actuator, it is often necessary that, in the event of a breakdown, in particular of the power supply, the actuator actuating member may return to a predetermined safety position. For example, if the object to be moved is a valve shutter, it must be possible, for safety reasons, that the actuator can close the valve in case of power failure by returning the shutter to its seat. The same requirement may be imposed on the construction of an actuator of a clutch for a motor vehicle, for example, which must always be able to disengage (or engage, as the case may be) the clutch, when a power failure occurs. actuator. A valve shutter actuator meeting the safety requirement of this type is described, for example, in US Pat. No. 5,984,260. In this case, a shaft rotatably mounted in a housing can be coupled to a shutter to cause displacements thereof. via a drive motor of this shaft. In case of a power failure of the engine, the shutter is returned to its seat by a safety device which comprises two springs for accumulating mechanical potential energy during normal operation of the actuator through a coupling. A blocking device powered in conjunction with the motor keeps the coupling engaged as long as the supply is present so that the drive shaft not only can move the shutter, but also act on the springs to accumulate therein. energy. However, when this power disappears, the coupling is disengaged, thus decoupling the shaft from the shutter. The energy accumulated in the springs is then released and applied to the shutter so that it can be moved to its support position on its seat.

  This prior mechanism has the disadvantage of keeping during normal operation a kinematic connection between the energy accumulator springs and the kinematic chain connecting the drive motor to the object to be moved (the shutter), a connection which is not broken only when the power supply to the actuator fails. Therefore, each time the object is moved in a given direction, the springs accumulate energy that must be provided by the engine in addition to the energy required to move the shutter. Although this additional energy is partially restored when the direction of movement is reversed by expansion of the springs, the fact remains that this arrangement increases the wear of moving parts and gives rise to unnecessary energy losses. , while in the presence of food, safety is obviously not threatened.

  The object of the invention is to provide an actuator which does not have this particular disadvantage. This object of the invention is achieved with an actuator comprising: - an actuating member, - a motor for causing the movements of said member between two positions, and - an elastic return device intended, in the event of a failure of supplying said actuator with energy, causing said member to move towards one of the positions considered as a safety position, said elastic return device comprising: an elastic energy storage element and a coupling for coupling said elastic element with said motor for raising said elastic member, and - a blocking device powered in conjunction with said motor to retain the energy accumulated in said elastic member as long as the power supply remains, and release this energy when the power supply comes to fall into failure, and apply it to said actuating member for its movement to the safety position, actuator in which the actuating member and said motor are in permanent kinematic connection and said coupling is arranged to decouple said elastic member of said motor in the presence of power supply of said actuator. Thanks to these characteristics, the elastic element is bandaged once and for all from the moment the actuator is powered, and does not restore its energy during normal operation thereof. The energy efficiency of the actuator is thus better, and its wear can be limited to a minimum. According to other optional features of the actuator according to the invention: - said elastic element is a spring formed of a spirally wound strip, - said coupling comprises a first disk-shaped element 35 coupled to said spring and a second element disc-shaped coupled to said motor, the first and second elements being rotatably mounted about a common axis, while being able to approach axially to ensure their coupling in rotation during the reassembly of said spring, - said first and second elements in the form of disc are provided on their faces opposite means facilitating their coupling in rotation when they are brought closer to one another, - said disc-shaped elements constitute translatable nuts on a common screw under the action of said motor or of said spring, the first disk-shaped member is provided with at least one tooth at its periphery and said locking device comprises an elec a magnet with a retractable bolt that has come out when the electromagnet is energized, to cooperate with said tooth and thus prevent the release of said spring after its reassembly, - there is provided a movable pawl between a locking position of said first disk-shaped element in which it cooperates with said tooth, and a second position in which it is spaced from the periphery of this first element, the transfer of the first position to the second position of said pawl being operated when the second element in form of disk moves away from the first disk-shaped element under the effect of its rotation around said screw, - said second disk-shaped element is fixed in rotation on the shaft of said motor, said locking device comprises a electromagnet of which said first disk-shaped element constitutes the movable armature, said first disk-shaped element is mounted axially movable and provided on its own this opposite to that facing the second movable member of at least one tooth cooperating with at least one tooth complementary to the fixed armature of said electromagnet to prevent the release of said spring when said electromagnet is excited, - said motor is interposed between said elastic return device and said object to be moved, - said elastic return device is interposed between said motor and said object to be moved. Other characteristics and advantages of the present invention will appear on reading the description which follows and on examining the appended figures, in which: FIG. 1 is a general perspective view of an assembly incorporating the characteristics of the invention; - Figure 2 is a perspective view, on an enlarged scale and cut away, of a portion of the actuator of Figure 1 illustrating its essential features for the invention; - Figure 2A shows a detail of the actuator; FIG. 3 is an axial sectional view of the portion of the actuator shown in FIG. 2, in the relaxed configuration of its elastic return element; FIGS. 4 and 5 are smaller-scale axial sections of the part of the actuator shown on FIGS. 2 and 3; FIG. 6 is a cross-sectional view taken along the line VI-VI of FIG. 5; - Figures 7 and 8 show axial sectional views another embodiment of the assembly according to the invention, respectively in normal operating mode and in the restitution mode of the energy accumulated in its elastic member; and FIGS. 7A and 8A are partial sectional views taken along the lines VII-VII and VIII-VIII of FIGS. 7 and 8. FIG. 1 represents, as an application of the invention, an actuator provided with an actuating finger for moving the stopper of a clutch interposed between an internal combustion engine and a gearbox of a motor vehicle, for example. This assembly comprises the following components: a drive motor 1, here by way of example of the electrical type, however any other mode of feeding is possible; a gearbox 2 for driving a device for transforming the rotational movement of the output of the gearbox 2 into a translational movement; a compensation and assistance mechanism 3 for the engine 1, provided more specifically in the context of the application of the actuator to a clutch as described herein; a finger 4 for actuating the diaphragm of the clutch to be controlled; and an elastic return device for the finger 4 in a safety position, more specifically incorporating the characteristics of the invention. In the context of the present embodiment of the invention, the actuating finger 4 constitutes the actuating member which in the example described is driven by an axial translation movement. However, neither the shape nor the nature of the movement printed on this actuating member are limiting to the scope of the invention. Likewise, the mechanism or object controlled by the actuator (in the example a clutch abutment) can be of any kind, provided, however, that it has a safety position in which it must always be brought back in the event of a breakdown. the power supply of the actuator. Finally, the term moving or displacement associated with the actuating member covers any movement of this member (rotation about its axis, rectilinear translation, etc.), or even a part of this member, that this displacement is made by the intermediate of reducers or other transformers of movement or not.

  The structure of the device 5 for elastic return of the finger 4 is shown in detail in FIGS. 2, 2A and 3. It comprises a cylindrical housing 6 fixed in axial alignment (axis AA) on the casing 7 of the engine 1 via 8 of the upper surface of this casing 6 extends axially inwardly a central sleeve 9 in which is engaged by force a screw 10. A resilient element 11 formed by a spiral wound coil spring is recessed at its outer end in the housing 6. Its inner end is embedded in the tubular nozzle 12 of a reel 13 which comprises a plate 14 forming a first disk-shaped element constituting a nut. This plate is secured to this end piece 12 and screwed onto the screw 10. As can be seen in particular in FIG. 6, at least one blocking tooth 15 (four teeth are provided in the example) extend outwardly. from the periphery of the plate 14. They have a profile such that they oppose the relaxation of the spring 11 when it is reassembled.

  A coupler 16 has a second disc-shaped member 17 constituting a nut. This element or disc 17 is screwed onto the screw 10. Two pillars 18 extend axially from the face of the disc 17 opposite the reel 13. They are placed at the periphery thereof in diametrically opposite positions.

  These pillars 18 cooperate with a drive interface 19 formed of a central hub 20 from which diametrically extend two drive arms 21 intended to exert a rotational force on the coupler 16. The central hub 20 is integral with the end of the shaft 22 of the drive motor 1 (see Figure 3). The opposite faces of the plate 14 and the disc 17 are provided with complementary ribs 30, 23 and 24 respectively, forming teeth and intended to promote good transmission of movement and torque (see in particular Figure 2A). One can provide two pairs of complementary ribs 23, 24 arranged at 180 on the plate 14 and the disk 17, or possibly a single pair of complementary ribs. As can be seen in FIG. 2A, these ribs each have a clearance angle D whose value must be greater than or equal to the angle of

  6 the helix described by these ribs when the plate 14 and the disc 17 rotate around the screw 10. The contact faces of the ribs 23, 24 are, for their part, substantially parallel to the axis of the screw 10.

  The height H of these ribs should be just greater than half the pitch of the screw 10 in the case where there are two pairs of ribs 23, 24 arranged at 180, and just above this screw pitch in the case of a only pair of ribs. Thus there is no axial contact between the ribs on the plate 14 and the disc 17, and between the ribs on the disc 17 and the plate 14. The ribs, via their contact face, transmit the tangentially. Note that in a variant (not shown), it could be envisaged that the cooperation between the plate 14 and the disk 17 is done by friction, thanks to appropriate friction materials coating the respective faces of this plate and this disk.

  The elastic return device 5 also comprises a locking device formed of an electromagnet 25 fixed on the casing 6. Its core comprises a retractable bolt 26 (FIG. 6) which, when the electromagnet is energized, enters the casing 6 at the height of the teeth 15 of the plate 14 of the reel 13. Under these conditions, this bolt is able to block the rotation of this plate.

  On the other hand, when the electromagnet is not excited, the bolt 26 is retracted into the housing of the electromagnet 25, thus releasing the winder 13. The electromagnet 25 is electrically connected in parallel to the motor 1 so that in the absence of power thereof, it can not block the plate 14. The resilient return device 5 finally comprises, optionally, a locking pawl 27 articulated on a fixed pivot 28 to be able to swing in a radial plane with respect to the axis AA. The edge of the pawl 27 turned towards the plate 14 and the disc 17 is shaped so as to act as a cam surface 29 cooperating with the periphery of the disk 17. At its upper part, this edge has a tooth 30 placed at the height of the periphery of the plate 14 to cooperate with the teeth 15 thereof. The cam surface 29 has two plates 29a and 29b inclined with respect to each other so that when the disc 17 is in the high position, the pawl 27 is spaced outwards, its tooth 30 then being discarded. On the other hand, in its low position, the disk 17 inclines the pawl 27 so that the tooth 30 can obstruct this path. The operation is as follows.

  Before the first power up of the motor 1 and the electromagnet 25, the elastic return device is in the configuration shown in FIGS. 2 and 3. The winder 13 and the coupler 16, which together form a coupling are engaged by the ribs 23, 24, and are in their low position. The spring 11 is released and takes a frustoconical body shape (Figure 3). The bolt 26 is released and the pawl 27 is tilted in its inclined position. When the voltage is applied for the first time, the motor 1 is set in motion and the electromagnet 25 excited, which causes the following operations.

  The actuating finger 4 is retracted, the driving interface 19 rotates and the bolt 26 is released. The coupler 16, rotating under the action of the driving interface 19, drives the reel 13 through the ribs 23, 24, the assembly of the coupling 13, 16 screwing on the screw 10 while moving towards the high.

  The spring 11 is raised and the pawl 27 is placed in its spaced position as soon as the periphery of the disc 17 leaves the portion 29a of the cam 29. The elastic return device is then bandaged and the clutch controlled by the finger 4 is engaged (Figure 4). Then, the direction of rotation of the motor 1 is reversed. The coupling formed by the coupler 16 and the reel 13 is then disengaged, the coupler 16 descending by unscrewing on the screw 10. However, the reel 13 is blocked by the bolt 26 coming out of the electromagnet 25, then when the coupler 16 is again at the height of the portion 29a of the cam surface 29, the pawl 27 tilts and is placed in front of one of the teeth 15 of the reel 13. Therefore, the clutch is disengaged and one can start the heat engine with which it is coupled. During the operation of the clutch, the coupler 16 follows the movements of the finger 4 by screwing and unscrewing itself on the screw 10, but the reel 13 remains locked in rotation thanks to the electromagnet 25 so that the spring He can not relax.

  It will be noted that the combination of the clearance D of the ribs 23, 24 (see FIG. 2A) with a height H of these ribs just greater than half the pitch of the screw 10 (or at this screw pitch, depending on the variant chosen), allows the escapement of the coupler 16 relative to the reel 13 while maximizing the contact surface between these ribs. Thus the clearance D allows the ribs 23 and 24 not to be driven by axial contact when the plate and the disk are distant one turn of the coupling (or a half turn according to the embodiment variant), it is that is, the contact faces of the ribs cooperate. The height H of the ribs, greater than

  8 steps (or half step) of the screw, allows the ribs é, 24 to achieve a purely tangential coupling, without axial contact of the ribs respectively with the disc and the tray vis-à-vis. When during normal operation, the power supply fails, the electromagnet 25 is de-energized. The reel 13 is then unlocked (withdrawal of the bolt 26) for all positions of the coupler 16 other than the lowest (disengaged position which corresponds to the safety position). As a result, the spring 11 is released, the coupling between the reel 13 and the coupler 16 is realized and the mechanical potential energy accumulated in the spring 11 brings the assembly to the safety position, rotating at the same time time the engine 1 (clutch disengaged). If the elastic return device comprises the optional pawl 27 as shown in the figures, it does not hinder this operation because the retractor 13 drops in concert with the coupler 16. The pawl can no longer block the rotation of this latest. However, the presence of the pawl 27 prevents that under normal operating conditions, at each cut-off of the heat engine, the spring 11 is released, then must be reassembled when the engine is restarted. This pawl 27 is therefore advantageous, but not essential to ensure safety.

  When the engine is shut down under normal conditions, the engine 11 is controlled so as to disengage the clutch. The coupler 16 returns to its low position so that the pawl 27 will occupy the inclined position to lock the reel 13. When the power supply is then cut, this blocking continues thanks to the pawl 27 then inclined. The spring 11 remains up, even if the power is cut off by stopping the engine. Thus the pawl 27 has the advantage of avoiding, under normal operating conditions, the relaxation of the spring 11 at each extinction of the engine.

  Figures 7 and 8 show another embodiment of the invention which can also advantageously apply to a clutch associated with a heat engine, application to which it is however not limited. In this case, in a common housing 40 are housed both the drive motor 41 (here also of electrical type by way of example) of the actuator and an elastic return device 42, the assembly being traversed by a shaft 43 of axis BB, common to these and rotatably mounted in the housing 40.

  9 This shaft 43 is coupled to an actuating member (shown in Figures 7 and 8 by the rectangle O), which may be similar to the finger 4 of the previous embodiment. The shaft 43 carries a transverse plate 44 which is integral in rotation and is part of a coupling 45. This plate 44 is interposed between the motor 41 and a sleeve 46 of the elastic return device 42, sleeve which is rotatably mounted around the shaft 43. A spirally wound strip spring 47 (shown only schematically) surrounds the sleeve 46 by being embedded at one end, its other end being embedded in the housing 40. A pinion 48 is formed at the end of the sleeve 46 closest to the motor 41. It meshes with an internal toothing of an annular paddle 49 which surrounds it being able to both rotate about the axis BB and move axially relative thereto.

  This pallet 49 cooperates with a locking device formed of an electromagnet 50 of which it constitutes the mobile armature and which comprises an annular magnetic armature 51 fixed on the casing 40 and having a U-shaped section. This armature 51 serves as housing to a coil 52. This coil is connected directly to a power source which supplies the operating voltage to the actuator. The pallet 49 is thus attracted by the armature 51 as soon as it is turned on. Several return springs 53 are interposed between the coil 52 and the pallet 49 to urge it towards the plate 44 against the magnetic action generated, if necessary, by the electromagnet 50. The pallet Each of the faces has at least one tooth 54 and 55 respectively. In the example, two pairs of teeth are provided in diametrically opposed positions. To each of the teeth 54 and 55 are respectively conjugate teeth 56 formed on the plate 44 and two teeth 57 in radial alignment, the latter being formed respectively on the upper edges of the U-shaped frame 51 (see FIGS. 7A and 8A). . All these teeth have a rectangular triangle profile erected respectively on the faces of their supports (or on the edge with respect to the teeth of the frame 51), and the conjugate teeth cooperate with each other by their sides. which stand perpendicular to the surface or the edge of their support, as shown in FIGS. 7A and 8A.

  As a variant, it could be envisaged that the cooperation between the plate 44 and the pallet 49 is done by friction, thanks to suitable friction materials coating the respective faces of this plate and this pallet. This variant would however assume that the electromagnet 50 is sized so as to be able to apply a sufficiently large axial pressing force to the pallet 49. The operation of this embodiment is as follows. When the actuator is powered up, the motor 41 is energized while the coil 52 is not yet powered. The motor 41 raises the spring 47 to accumulate mechanical potential energy, placing at the same time the actuating member O in a determined end position. The driving force of the motor 41 then passes through the plate 44, the conjugate teeth 54 and 56, the pallet 49, the internal toothing thereof, the pinion 48 and the sleeve 46 (FIGS. 7 and 7A). At the end of this process, the coil 52 is excited via an electronic delay device known per se and belonging to the control electronics (not shown) of the actuator. The excitation of the coil 52 causes the axial displacement of the pallet 49 thanks to the magnetization of the armature 51, which causes the teeth 55 to lock on the teeth 57. Therefore the spring 47 can not relax and keep the energy he has accumulated. The actuator can thus operate, the motor 41 being able to move the actuating member O as needed through the shaft 43 without the upset state of the spring 47 changing. The coil 52 remains energized. If under these conditions occurs a power failure, the coil 52 is de-energized, the paddle 49 is biased by the springs 53 by coupling to the plate 44 (Figure 8 and 8A). As a result, the energy accumulated in the spring 47 is released and the motor 41, now also deprived of tension, is rotated through the shaft 43 while the actuating member O performs the movement. necessary to reach its security position. The same process occurs if the supply voltage of the actuator is cut off under normal operating conditions. When the supply voltage is again applied, the spring 47 is raised in the same manner as described above, after which the actuator can operate normally.

  It should be noted that unlike the first embodiment in which the energy storage spring 11 is released only in the event of a power failure of the actuator, the spring of the second embodiment releases its accumulated energy whenever the power supply to the actuator is removed, whether in normal conditions or in case of failure of the latter. It will also be noted that the second embodiment has a particularly compact shape because the assembly is housed in a single casing and the drive motor is at the end of the mechanism relative to the actuating member. Of course, the present invention is not limited to the embodiments described and shown, provided as simple examples.

Claims (10)

  An actuator comprising: - an actuating member (4; O), - a motor (1; 41) for causing the movements of said member (4; 0) between two positions, and - an elastic return device (5; 42), in the event of a power supply failure of said actuator, causing said member (4; O) to move towards one of the positions considered as a safety position, said elastic return device (5; ) comprising: - an elastic energy storage element (11; 47) and a coupling (13, 16; 45) for coupling said resilient element with said motor (1; 41) for raising said resilient element, and - a blocking device (25; 50) supplied in conjunction with said motor for retaining the energy accumulated in said elastic element (11; 47) as long as the power supply remains, and releasing this energy when the power supply fails. , and apply it to said actuating member (4; 0) for its moving to the safety position, actuator in which said actuating member (4; 0) and said motor (1; 41) are in permanent kinematic connection and said coupling (13, 16; 45) is arranged to uncouple said elastic element (11; 47) from said motor in the presence of power supply of said actuator.   An actuator according to claim 1, wherein said resilient member is a spring (11; 47) formed of a spirally wound strip.   An actuator according to claim 2, wherein said coupling (13, 16; 45) comprises a first disk-shaped element (14; 49) coupled to said spring (11; 47) and a second disk-shaped element (17; 44) coupled to said motor, the first and second disk-shaped members being rotatably mounted about a common axis (AA; BB), while being able to move axially towards their rotational coupling during reassembly of said spring (11). 47).   4. An actuator according to claim 3, wherein said first and second disk-shaped elements (14, 17; 49, 44) are provided on their faces opposite means (23, 24; 54, 56) facilitating their coupling in rotation when they are close to each other.   5. An actuator according to claim 4, wherein said disk-shaped elements (14; 17) constitute translatable nuts on a common screw (10) under the action of said motor (1) or said spring (11). 13   An actuator according to any one of claims 3 to 5, wherein the first disk-shaped member (14) is provided with at least one tooth (15) at its periphery and said locking device comprises an electromagnet. (25) provided with a retractable bolt (26) which is released when the electromagnet is energized, to cooperate with said tooth (15) and thus prevent the relaxation of said spring (11) after its reassembly.   7. An actuator according to claims 5 and 6 wherein there is provided a pawl (27) movable between a locking position of said first disk-shaped member (14) in which it cooperates with said tooth (15), and a second position in which it is spaced from the periphery of this first element (14), the transfer of the first position to the second position of said pawl (27) being effected when the second disk-shaped element (17) moves away from the first element disk-shaped (14) under the effect of its rotation around said screw (10).   8. An actuator according to one of claims 3 and 4, wherein said second disk-shaped element (44) is fixed in rotation on the shaft (43) of said motor, said locking device comprises an electromagnet (50). ) of which said first disk-shaped element (49) constitutes the movable armature, said first disk-shaped element (49) is axially movable and provided on its face opposite to that facing the second mobile element of at least a tooth (55) cooperating with at least one complementary tooth (57) of the fixed armature (51) of said electromagnet (50) to prevent relaxation of said spring (47) when said electromagnet is energized.   9. An actuator according to any one of the preceding claims wherein said motor (1) is interposed between said elastic return device (5) and said actuating member (4).   10. An actuator according to any one of the preceding claims, wherein said elastic return device (42) is interposed between said motor (41) and said actuator (0).