Clutch, in particular for a motor vehicle

Abstract

A clutch release bearing (17), in particular for a motor vehicle, having: a tubular body (30) through which at least one input shaft (11) of a gearbox is intended to pass; at least one actuator having a part, movable in translation along the axis (X) of the body (30), intended for actuation of a clutch diaphragm; a target (28a, 28b) whose position is representative of the position of the movable part of the actuator; and a detector (29a, 29b) capable of detecting the position of the target (28a, 28b). The target (28a, 28b) is offset angularly from the detector (29a, 29b) with respect to the axis (X) of the body (30).

Claims

1. A clutch release bearing (17), in particular for a motor vehicle, having: a tubular body (30) through which at least one input shaft (11, 22) of a gearbox is intended to pass; at least one actuator (16a, 16b) having a movable part (26a, 26b), movable in translation along the axis (X) of the body (30), intended for actuation of a clutch diaphragm (13, 24); a target (28a, 28b), having a magnetic field (B1, B2), whose position is representative of the position of the movable part (26a, 26b) of the actuator (16a, 16b); and a detector (29a, 29b) capable of detecting the position of the target (28a, 28b), wherein the target (28a, 28b) is offset angularly from the detector (29a, 29b) with respect to the axis (X) of the body (30) wherein, said magnetic field (B1, B2) of said target (28a, 28b) is directed toward the detector (29a, 29b).

2. The clutch release bearing (17) according to claim 1, wherein the target (28a, 28b) is located, at least in part, radially facing toward the detector (29a, 29b) or on the same circumference as the detector (29a, 29b).

3. The clutch release bearing (17) according to claim 2, wherein said at least one actuator comprises a pair of actuators, including a first actuator (16a) and a second actuator (16b) located radially inside of the first actuator (16a), each actuator (16a, 16b) having an associated movable part (26a, 26b), an associated target (28a, 28b) whose position is representative of the position of the associated movable part (26a, 26b) of the first or second actuator (16a, 16b), and an associated detector (29a, 29b) capable of detecting the position of said target (28a, 28b) associated with said first or second actuator, at least one of said targets (28a, 28b) being offset angularly with respect to the associated detector (29a, 29b) and being located, at least in part, radially facing toward said associated detector (29a, 29b) or on the same circumference as said associated detector (29a, 29b).

4. The clutch release bearing (17) according to claim 2, wherein the detector (29a, 29b) and/or the target (28a, 28b) are of the Hall effect, Foucault current, PLCD, or flux gate type.

5. The clutch release bearing (17) according to claim 1, wherein said at least one actuator comprises a pair of actuators, including a first actuator (16a) and a second actuator (16b) located radially inside of the first actuator (16a), each actuator (16a, 16b) having an associated movable part (26a, 26b), an associated target (28a, 28b) whose position is representative of the position of the associated movable part (26a, 26b) of the first or second actuator (16a, 16b), and an associated detector (29a, 29b) capable of detecting the position of said target (28a, 28b) associated with said first or second actuator, at least one of said targets (28a, 28b) being offset angularly with respect to the associated detector (29a, 29b) and being located, at least in part, radially facing toward said associated detector (29a, 29b) or on the same circumference as said associated detector (29a, 29b).

6. The clutch release bearing (17) according to claim 5, wherein the detectors (29a, 29b) of the first and second actuators (16a, 16b) are offset angularly from one another with respect to the axis (X) of the tubular body (30).

7. The clutch release bearing (17) according to claim 6, wherein the detector (29a, 29b) and/or the target (28a, 28b) are of the Hall effect, Foucault current, PLCD, or flux gate type.

8. A double clutch (1), wherein it has a clutch release bearing (17) according to claim 6.

9. The clutch release bearing (17) according to claim 5, wherein the detectors (29a, 29b) of the first and second actuators (16a, 16b) are located in a single radial plane (R1), the associated targets (28a, 28b) of the first and second actuators (16a, 16b) being offset angularly from one another with respect to the axis (X) of the tubular body (30).

10. The clutch release bearing (17) according to claim 9, wherein the detector (29a, 29b) and/or the target (28a, 28b) are of the Hall effect, Foucault current, PLCD, or flux gate type.

11. A double clutch (1), wherein it has a clutch release bearing (17) according to claim 9.

12. A double clutch (1), wherein it has a clutch release bearing (17) according to claim 5.

13. The clutch release bearing (17) according to claim 5, wherein the detector (29a, 29b) and/or the target (28a, 28b) are of the Hall effect, Foucault current, PLCD, or flux gate type.

14. The clutch release bearing (17) according to claim 1, wherein the detector (29a, 29b) and/or the target (28a, 28b) are of the Hall effect, Foucault current, PLCD, or flux gate type.

15. A double clutch (1), wherein it has a clutch release bearing (17) according to claim 14.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood, and other details, characteristics, and advantages of the invention will emerge, upon reading the description below provided as a non-limiting example with reference to the attached drawings, in which:

(2) FIG. 1 is a partial, axially sectioned view of a double clutch of the existing art;

(3) FIG. 2 is a sectioned half-view of a part of the double clutch of FIG. 1;

(4) FIGS. 3 to 6 are schematic views, sectioned along a radial plane, of a release bearing for operation of a double clutch, according to four embodiments of the invention.

(5) FIGS. 1 and 2 depict a double clutch 1 of the existing art, known from the Applicant's document FR 2 803 346.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

(6) A clutch has a dual mass flywheel 2, only part of which has been depicted, comprising a primary flywheel 3 integral with a driving shaft, for example a crankshaft 4 of an internal combustion engine of a motor vehicle, and a secondary flywheel 5 equipped with a torque limiter 6, and means (not depicted) for damping and absorbing vibration and rotational irregularities, which are arranged between primary flywheel 3 and secondary flywheel 5.

(7) Secondary flywheel 5 constitutes a reaction plate of a first clutch mechanism, and is fastened to a recessed cover 7.

(8) The first clutch mechanism comprises a first friction disk 8 carrying friction linings 9 and having a splined hub 10 rotationally coupled to a first input shaft 11, associated with the odd-numbered gear ratios, of a gearbox, and a first pressure plate 12 movable in translation along axis X of hub 10 and of crankshaft 4. First pressure plate 12 is movable between an engaged position in which first friction disk 8 is clamped between first pressure plate 12 and first reaction plate 5 in order to transmit a torque from crankshaft 4 to shaft 11, and a disengaged position in which first friction disk 8 is released. The displacement of first pressure plate 12 is actuated by means of a first diaphragm 13 and a connecting member constituted by a movable cover 14. First diaphragm 13 is mounted tiltingly on cover 7 by means of rivets 15 that ensure centering of said diaphragm 13 while allowing it to tilt. First diaphragm 13 takes the form of an elastic annular metal sheet that abuts against cover 7 and tilts around said abutment region.

(9) First clutch 7 is controlled by means of a first actuator 16a of a release bearing 17, interacting with the radially inner periphery of first diaphragm 13. First diaphragm 13 constitutes a lever transmitting the force applied by first actuator 16a to first pressure plate 8 by means of movable cover 14.

(10) The first clutch mechanism is of the normally open type. The inactive position of first diaphragm 13 thus corresponds to a disengaged state of the first clutch mechanism. First diaphragm 13 preferably exhibits a portion of the Belleville disc type, allowing first diaphragm 13 to be returned toward its inactive position.

(11) With first diaphragm 13 in the inactive position, i.e. when first actuator 16a is exerting little or no force on first diaphragm 13, first diaphragm 13 thus exerts little or no force on first pressure plate 12. First pressure plate 12 is moved away from first reaction plate 5 via appropriate return means, such as elastic tongues, in order to release first friction disk 8.

(12) The double clutch furthermore has a second clutch mechanism having: a second reaction plate 18, the radially outer periphery of which is rotationally coupled to first reaction plate 5 and/or to cover 7; a second friction disk 19 carrying friction linings 20 and having a splined hub 21 rotationally coupled to a second input shaft 22, associated with even-numbered gear ratios, of a gearbox; and a second pressure plate 23 movable in translation along axis X of hub 21. Second pressure plate 23 is movable between an engaged position in which second friction disk 19 is clamped between second pressure plate 23 and second reaction plate 18 in order to transmit a torque from crankshaft 4 to shaft 22, and a disengaged position in which second friction disk 19 is released. The displacement of second pressure plate 23 is actuated by means of a second diaphragm 24. The latter is mounted tiltingly on cover 7 by means of rivets 15 and takes the form of an elastic annular metal sheet that abuts against cover 7 and tilts around said abutment region.

(13) The second clutch mechanism is controlled by means of a second actuator 16b of release bearing 17, interacting with the radially inner periphery of second diaphragm 24. Second diaphragm 24 constitutes a lever transmitting the force applied by second actuator 16b to second pressure plate 23.

(14) The second clutch mechanism is likewise of the normally open type. The inactive position of second diaphragm 24 thus corresponds to a disengaged state of the second clutch mechanism. Second diaphragm 24 preferably exhibits a portion of the Belleville disc type, allowing second diaphragm 24 to be returned toward its inactive position.

(15) With second diaphragm 24 in the inactive position, i.e. when second actuator 16b is exerting little or no force on second diaphragm 24, second diaphragm 24 thus exerts little or no force on second pressure plate 23. Second pressure plate 23 is moved away from second reaction plate 18 via appropriate return means, such as elastic tongues, in order to release second friction disk 19.

(16) As is more evident from FIG. 2, release bearing 17 has two concentric annular receptacles 25a, 25b, having an axis X, in which are mounted pistons 26a, 26b belonging to the aforesaid actuators 16a, 16b. A first, radially outer annular piston 26a is intended to actuate first diaphragm 13 by means of a first ball bearing 27a. A second, radially inner annular piston 26b is intended to operate second diaphragm 24 by means of a second ball bearing 27b. Pistons 26a, 26b are movable in translation along axis X, and their displacement is controlled hydraulically by means of pressurized fluid supply conduits. Actuators 16a, 16b of this type are called concentric slave cylinders (CSC).

(17) For precise control of the operation of the first and second clutch mechanisms, it is necessary to known the positions of first and second diaphragms 13, 24 and thus of first and second pistons 26a, 26b. This type of information in particular enables identification of any change in the biting point of each clutch mechanism, for correction purposes. It is known that the biting point is that position of the diaphragm or of the piston at which a torque begins to be transmitted through the clutch mechanism in question.

(18) Information regarding the positions of the first and second pistons makes it possible to:

(19) precisely regulate the transmission of torque in each of the clutches;

(20) establish diagnostics as necessary;

(21) evaluate wear of the friction linings;

(22) detect any operating defect in the system, for example a blockage.

(23) For this purpose, the invention proposes to equip the first and second actuators 16a, 16b with noncontact position sensors.

(24) More particularly, first and second pistons 16a, 16b are equipped respectively with a first target 28a and a second target 28b interacting respectively with a first detector 29a and a second detector 29b each capable of detecting the position, along axis X, of the corresponding target 28a, 28b.

(25) An electronic system for processing the signal emitted by detector 29a, 29b is associated with each detector 29a, 29b. The electronic processing system supplies an output signal providing a datum regarding the relative position of target 28a, 28b with respect to detector 29a, 29b. The target and the detector constitute a noncontact position sensor. A sensor of this kind can be, for example, of the Hall effect, Foucault current, permanent magnetic linear contactless displacement (PLCD), or flux gate type.

(26) In a first embodiment illustrated in FIG. 3, release bearing 17 has a tubular body 30 comprising three concentric annular walls 31, 32, 33 delimiting between them two concentric annular spaces 25a, 25b into which pistons 26a, 26b of actuators 16a, 16b are engaged. These walls have also been labeled with the same references in FIGS. 1 and 2 that illustrate the existing art. The first, radially outer piston 26a is engaged into space 25a delimited between annular walls 31 and 32, and the second, radially inner piston 26b is engaged into space 25b delimited between annular walls 32 and 33.

(27) In this embodiment, first target 28a is offset angularly, with respect to axis X, from first detector 29a and is located radially facing toward, or on the same circumference as, first detector 29a. First detector 29a and first target 28a are both located radially outside of annular wall 31. For this, first target 28a extends, for example, radially outward from first piston 26a.

(28) Second target 28b is located radially in the same plane as second detector 29b. More particularly, second target 28b is located radially between annular walls 32 and 33, and second detector 29b is located radially inside of wall 33.

(29) Radial plane R2 passing through second target 28b and second detector 29b is offset angularly (by an angle α) from radial plane R1 passing through first detector 29a. In addition, first target 28a is offset angularly from first detector 29a on the other side of radial plane R2.

(30) FIG. 4 illustrates a second embodiment of the invention in which first target 28a is located radially in the same plane R1 as first detector 29a. More particularly, first target 28a is located radially outside of first detector 29a, which in turn is located radially outside of wall 31. For this, first target 28a extends, for example, radially outward from first piston 26a.

(31) In addition, second target 28b is offset angularly, with respect to axis X, from second detector 29b and is located radially facing toward, or on the same circumference as, second detector 29b. Second detector 29b and second target 28b are both located radially inside of annular wall 33. For this, second target 28b extends, for example, radially inward from second piston 26b. In this embodiment, first detector 29a and second detector 29b are located in a single radial plane R1.

(32) FIG. 5 illustrates a third embodiment of the invention in which first target 28a is located radially in the same plane R1 as first detector 29a. More particularly, first target 28a is located radially outside of first detector 29a, which in turn is located radially outside of wall 31. For this, first target 28a extends, for example, radially outward from first piston 26a.

(33) In addition, second target 28b is offset angularly, with respect to axis X, from second detector 29b and is located radially facing toward, or on the same circumference as, second detector 29b. Second detector 29b and second target 28b are both located radially inside of annular wall 33. For this, second target 28b extends, for example, radially inward from second piston 26b. In this embodiment, second detector 29b is offset angularly from first detector 29a, second target 28b being located, for example, in the same radial plane R1 as first detector 29a and first target 28a.

(34) FIG. 6 illustrates a fourth embodiment of the invention in which first target 28a is offset angularly, with respect to axis X, from first detector 29a and is located radially facing toward, or on the same circumference as, first detector 29a. First detector 29a and first target 28a are both located radially outside of annular wall 31. For this, first target 28a extends, for example, radially outward from first piston 29a.

(35) In addition, second target 28b is offset angularly, with respect to axis X, from second detector 29b and is located radially facing toward, or on the same circumference as, second detector 29b. Second detector 29b and second target 28b are both located radially inside of annular wall 33. For this, second target 28b extends, for example, radially inward from second piston 26b. In this embodiment, first detector 29a and second detector 29b are located in a single radial plane R1, first and second targets 28a, 28b being offset angularly oppositely from one another with respect to radial plane R1.

(36) In each of the aforementioned embodiments, the magnetic field emitted by each target 28a, 28b is directed toward the corresponding detector 29a, 29b. In the case of the embodiments of FIGS. 3, 4, and 5, for example, the magnetic field of first target 28a, labeled B1, is thus perpendicular to the magnetic field of second target 28b, labeled B2.

(37) In general, it is useful to ensure that magnetic field B1 is not directed toward second detector 29b and that magnetic field B2 is not directed toward first detector 29a, which is the case for each of the aforementioned embodiments. It is thereby possible to prevent magnetic field B1 of first target 28a from being detected by second detector 29b, or from disrupting measurement of the position of second target 28b by second detector 29b, and to prevent magnetic field B2 of the second target from being detected by first detector 29a, or from disrupting measurement of the position of first target 28a by first detector 29a.

(38) These various embodiments of the invention allow the radial and/or axial space requirement of release bearing 17 to be reduced using conventional, inexpensive, and proven sensors, while avoiding possible interference among the sensors.