GB2204374A

GB2204374A - Actuating device for a motor vehicle clutch with alternative manual and power inputs

Info

Publication number: GB2204374A
Application number: GB08804517A
Authority: GB
Inventors: Franz Nagler; Christoph Thielen
Original assignee: Sachs Systemtechnik GmbH
Current assignee: Sachs Systemtechnik GmbH
Priority date: 1987-03-03
Filing date: 1988-02-26
Publication date: 1988-11-09
Anticipated expiration: 2008-02-26
Also published as: GB2204374B; GB8804517D0; DE3706850A1; FR2611614B1; FR2611614A1

Abstract

The actuating device for a motor vehicle clutch comprises a carrier part on which are mounted an output member (29, 31, 35) and two input members (41, 69) adapted for movement relatively to each other and relative to the output member. A first input member (41) of the two input members is movable by means of a servo positioning drive; the second input member (69) is movable by a clutch pedal. The input members (41, 69) have driving abutments (51, 81) with which are associated counter abutments (59, 61, 77) on the output member (29, 31, 35) and which, independently of one another, for the clutch positioning movement, couple the input members (41, 69) together with the output member (29, 31, 35). In the event of the servo positioning drive failing, the input member (69) permits of emergency actuation of the clutch. In order to prevent unintended engagement of the clutch which has been disengaged solely via the servo positioning drive, an interlocking device (87) is preferably provided which locks the output member (29, 31, 35) in its position relative to the carrier part in which the clutch is fully disengaged. The second input member (69) has a control surface (99) which releases the interlocking device (87) in that position of the second input member (69) which is associated with the disengaged clutch. The device may be part of a clutch control arrangement which monitors engine speed to avoid stalling. The servo arrangement is preferably an electric motor (7) driving a worm (45) meshing with a worm gear input member (41). <IMAGE>

Description

Actuating device for a motor vehicle clutch The invention relates to an actuating device for a motor vehicle clutch, according to the preamble to Patent Claim 1.

Already known from DE-OS 34 38 594 is a motor vehicle clutch which is engaged and disengaged via a servo positioning drive.

The servo positioning drive is controlled by a desired value transmitter connected to the clutch pedal. Furthermore, the servo positioning drive is influenced by a control arrangement which for damping rotary oscillations in the drive line of the motor vehicle, adjusts a predetermined clutch slip dependent upon the engine speed. The prior art actuating device is intended solely for an electrical control arrangement and admits of no mechanical emergency actuation of the clutch.

A object of the invention is to provide an operationally reliable and structurally simple actuating device which makes it possible in an emergency to actuate the clutch if the servo posi- tioning drive fails.

According to the invention, this problem is resolved by the features indicated in the characterising part of Patent Claim 1.

The actuating device according to the invention comprises two input members guided on a carrier part for movement relative to each other and to am output member which actuates the clutch. A first of these input members is movable via a servo positioning drive, for example an electric motor or the like. The second input member is movable via an operating device, for example a clutch pedal. The input members have driving abutments with which are associated counter abutments on the output member, so \ that independently of one another they can drive the output member for the clutch positioning movement. Such an actuating device can be constructed at relatively low structural cost.

The servo positioning drive comprises a desired value transmitter which is adjustable via the operating device, for example the clutch pedal, and positions the output member to a value determined by the desired value transmitter. However, the servo positioning drive can also be dependent upon additional control signals. For example, the servo positioning drive can be used in conjunction with a rotary vibration damping slip control arrangement, such as is known, for example, from DE-OS 34 38 594. It is possible furthermore to envisage the clutch being disengaged as a function of the engine speed, in order to prevent the engine stalling.Particularly in the case of the last-mentioned developments, in which the clutch is moved into the disengaged position independently of actuation of the clutch pedal, there is the danger that if there is a defect in the control arrangement, the disengaged clutch may be unexpectedly engaged. To prevent this, a preferred development incorporates an interlocking device which locks the output member in its position relative to the carrier part in hitch the clutch is completely disengaged. The second input member comprises a control face which in the position of the second input member which is associated with the disengaged clutch, unlocks the interlocking devie. The interlocking device is thus ineffective as long as the output member, together with the second input member which is adapted for movement via the clutch pedal, is moved into the disengaged position.If the clutch is disengaged independently of the clutch pedal, for example via a disengaging or similar control arrangement, then the output member remains in the disengaged position until it is unlocked again via the second input member by a depression of the clutch pedal. An actuating device of this type is particularly reliable in operation.

The input members and output members can be constructed as elemenus adapted for linear displacement on the carrier part. The actuating device can be constructed in a particularly compact fashion if the input members and the output member are constructed as axially ad jacen tl y disposed disc parts rotatable in respect of each other about a common axis of rotation. The drivingabutments or counter abutments then preferably take the form of cutouts shaped like segments of a circle and concentric with the axis of rotation and axial driving pins which engage the cut-outs.

Where the interlocking device is concerned, this is then expediently a catch which is resiliently guided on the carrier part and which co-operates with a driving pin on the output member, which couples the output member with the second input member.

Provided as a control surface there is on the second input member a cam path which co-operates with the catch and which curves like a segment of a circle about the axis of rotation.

In order to be able to transmit comparatively high disengaging forces also during continuous operation, the first input member is expediently a gearwheel rotatably mounted on a shaft and meshing with a driving gearwheel, particularly a driving worm, of the servo positioning drive, while the output member comprises, disposed on axially opposite sides of the gearwheel but non-rotatably connected to each pother, two discs both of which can be coupled with the gearwheel via entraining abutment/counter abutment connections. To convert the rotary movement of the output member to a linear movement, there is preferably provided a clutch actuating push rod disposed axially between the two discs, being articulatingly connected to both discs in order to ensure symmetry in the initiation of force.In this case, the gearwheel is a segmental gearwheel, the push rod engaging into the gaps between the segments. The push rod is able to actuate the clutch directly via the disengagement system or can act on the transmitter cylinder of a hydraulic clutch actuating device.

By way of example, an embodiment of the invention will be explained in greater detail hereinafter with reference to the accompanying drawings , in which: Fig. 1 is a sectional view through an actuating device for a motor vehicle clutch; Fig. 2 is an exploded view of parts of the actuating device, and Fig. 3 is a detail view of an interlocking device for the actuator.

The actuating device shown in Fig. 1 permits of servo-assisted actuation of a motor vehicle friction clutch by means of a clutch pedal 1. The clutch pedal 1 is connected to a desired value position transmitter 3 which generates a desired position signal for a servo positioning drive generally designated 5. The servo positioning drive 5 comprises an electric positioning motor 7 which, in a manner described in greater detail hereinafter, moves the clutch disengaging device via the actuating device. The motor 7 is controlled by a regulator 9 to which in conventional manner an error signal is fed from a differential stage 11. The differential stage 11 generates the error signal as a function of the desired value signal from the desired value transmitter 3 and a signal from an actual value transmitter 13 corresponding to the actual position of the clutch disengaging device.The motor 7 is so controlled that, via the actuating device, it adjusts the clutch disengaging device to the position established by the clutch pedal 1. At an input 15, additional positioning signals can be fed to the servo positioning drive 5, the said additional positioning signals being supplied by a disengaging control or a slip adjusting control not illustrated in greater detail but for example of the type described in DE-OS 34 39 594. The disenga gin g control arrangement may be a constituent part of a clutch control which automatically controls the clutch after the manner of an automatic gearbox or may be a constituent part of a disengaging control arrangement which monitors the engine speed and prevents stalling of the engine.

The actuating device comprises a housing 17 in which a shaft 23 is mounted on two bearing flanges 19, 21, for rotation in ballbearings 25, 27. The shaft 23 carries two axially spaced-apart discs 29, 31 which are connected by a bearing journal 33 (Fig.2) of an output push rod 35 a rtarticulatingly connected to the discs 29, 31 to form one rotationally rigid unit. The push rod 35 is disposed axially between the discs 29, 31 and forms the outer member of the actuating device which acts on the clutch disengaging device directly or through a transmitter cylinder of a hydraulic clutch actuating system. The unit comprising the discs ?9, 31 is non-rotatably connected to the shaft 23 via a system of teeth 37 on the shaft 23 (Fig.l), coupled to the internally cut system of teeth on the disc 29.At one end, the shaft 23 carries an extension piece 39 coupled to the actual value transmitter 13 constructed as an angle transmitter and fixed on the housing 17.

Disposed axially between the two discs 29, 31 is a segment wormwheel 41 which is rotatably mounted on the shaft 23 via a ballbearing 43 in the same axis as the discs 29, 31. Meshing with the wormwheel 41 is a worm 45 driven by the motor 7. Flange discs 47, 49 axially on either side of the wormwheel 41 fix the wormwheel 41 on the outer race of the ball-bearing 43. The inner race of the ball-bearing 43 is axially fixed by annular projections on the discs 29, 31. The wormwheel 41 is rotatable relatively to the lateral discs 29, 31 and carries, projecting axially on both sides, an entraining pin 51 which engages into driving cut-outs 53, 55 which are shaped like segments of a circle and which extend coaxially around the shaft 23.Upon a rotation of the wormwheel 41 in the direction of an arrow 57, the driving pin 51 strikes end faces 59. 61 of the cut-outs 53, 55, so that the push rod 35 is moved into its disengaging direction indicated by an arrow 63, in which the clutch is disengaged. If the wormwheel 41 is driven against the direction of rotation 57, then the force of the clutch springs which acts on the disengaging device drives the push rod 35 against the direction 63 and the discs 29, 31 are entrained.

Fig.2 furthermore shows that the push rod 35 extends in the segmentally-shaped cut-out 65 in the wormwheel 41, to minimise the overall dimensions of the housing 17.

For an emergency actuation of the clutch independently of the servo positioning drive 5, a rope drum 69 is rotatably mounted in the same axis as the shaft 23, in the housing 17 and on a ball-bearing 67. The rope drum 69 is disposed axially alongside the lateral discs 29, 31 and is connected to the clutch pedal 1 via a traction cable 71. When the clutch pedal I is depressed, the drum 69 is rotated in the direction of an arrow 73, in the same direction as the disengaging direction 57 of rotation of the wormwheel 4 1. A torsion spring 75 anchored on the housing 1 7 at one end and on the drum 69 at the other pretensions the drum 69 so that it is in its inoperative engaged position.To couple the drum 69 to the discs 29, 31 and thus the push rod 35, the discs 29, 31 are provided with a driving pin 77 which traverses a cutout 79 in the drum 69 which is shaped like a segment of a circle and which equi-axially encircles the shaft 23. An end face 81 of the cut-out 79 strikes the driving pin 77 in the event of failure of the servo positioning drive 5 and, via the driving pin 77, entrains the discs 29, 31 for emergency actuation of the clutch.

The driving pin 77 is, to rigidify the unit formed by the discs 29, 31, connected to both discs and traverses the wormwheel 41 through a cut-out 83 which is shaped like a segment of a circle and which is in the same axis as the shaft 23. In the inoperative engaged position, the end face 81 of the cut-out 79 extends at a distance 85 from the driving pin 77. In normal operation, therefore, upon depression of the clutch pedal 1, the servo positioning drive 5 can rotate the discs 29, 31 via the wormwheel 41 before the surface 81 reaches the driving pin 77.

The positioning drive operates as follows: In normal operation, upon depression of the clutch pedal 1, the desired value transmitter 3 generates a desired signal which switches the motor 7 on until such time as the wormwheel 41 and thus the discs 29, 31 which are entrained by the driving pin 51 and the end faces 59, 61 are rotated into an angular position in which the push rod 35 has moved the clutch disengaging device into a position corresponding to the position of the pedal 1. The angular position of the discs 29, 31 is monitored via the angle transmitter 13 which is coupled to the discs 29, 31 via the shaft 23.Upon actuation of the pedal 1, the drum 69 is co-rotated, the drum 69 not however responding to the driving pin 77 under normally rapid actuation of the clutch pedal 1. however, if the clutch pedal 1 is depressed very rapidly so that the drum 69 catches up with the wormwheel 41, then the end face 81 of the drum 69 strikes the driving pin 77 and, without any assistance from the motor 7, the discs 29, 31 are rotated in the disengaging direction. The end faces 59, 61 of the discs 29, 31 are in this case lifted off the entraining pin 51 of the wormwheel 41. The positioning device can therefore move the clutch disengaging device at a higher positioning speed than is envisaged by the servo positioning drive 5.

In the event of the servo positioning drive 5 failing, then the clutch can be actuated on an emergency basis. The drum 69 which rotates in the direction of the arrow 73 as the pedal 1 is depressed moves the push rod 35 in the disengaging direction 63 via the end face 81 of the cut-out 79, the driving pin 77- and the lateral discs 29, 31. The driving pin 51 of the wormwheel 41 which is stationary by reason of the fault in the servo drive 5 is hereby lifted off the end faces 59, 61 of the cut-outs 53, 55.

As already explained, the actuating device can be disengaged independently of actuation of the clutch pedal 1 via the desired value signals which are conveyed at 15 (Fig.l). A control arrangement provided for the purpose disengages the clutch especially when the engine speed falls below a value at which the engine stalls. To prevent the clutch engaging again unexpectedly, for instance due to a fault or such like, without any intended

actuation of the clutch pedal 1, an interlocking device 87)which automatically engages in the clutch disengaging position, locking the discs 29, 31 and thus the push rod 35 in the disengaging position on the housing 17. The interlocking device 87 comprises disposed in the path of rotation of the driving pin 77, a catch 89 which, as is best shown in Fig.l, is guided non-rotatably but axially displaceably in an axial aperture 91 of the bearing flange 19, being biased by a thrust spring 93 in the direction of the drum 69. The free end of the driving pin 77 which emerges from the drum 69 is provided with a catch-mating surface 95. The catch-mating surface 95 points in the opposite direction to the directions of rotation 57 and 73 of the wormwheel 41 or of the drum 69 and the catch 89 is so disposed that in the disengaged position of the discs 29W' 31, it engages behind the catch-matching surface 95 and prevents reverse movement of the discs 29, 31.

The rope drum 69 comprises an annularly cylindrical projection 97 which at the same time carries the ball-bearing 67 and which overlaps the catch 89 in a radial direction. The annular axially directed end face of the projection 97 forms an axially rising cam face 99 which, when it is moved under the catch 89, lifts the catch 89 out of its engagement with the catch-mating surface 95.

The can face 99 is so disposed that upon pedal-induced rotation of the drum 69, it reaches the catch 89 inthe disengaged position.

Details of the interlocking device 87 can be ascertained from a radial view in Fig.3. The cam face 99 rises hereby from a low level 101 which permits of the interlocking effect and against the direction of rotation 73 to a level 103 which releases the interlock.

If the clutch is, without pedal actuation, disengaged solely via the servo positioning drive 5, then the driving pin 77 driven via the wormwheel 41 and the discs 29, 31, while the drum 69 is stationary, is moved hack in the direction of the arrow 73 into the interlocking position shown in Fig.3 in which the catch 89 retains the driving pin 77, even if the servo positioning drive 5 moves the worm gear 41 back against the direction of rotation 57. The interlocking effect is released if subsequently the clutch pedal 1 is depressed and the cam face 99 of the rope drum 69 which is thus moved into the disengaging position releases the engagement of the catch 89. In normal operation, depression of the clutch pedal 1 renders the interlocking device 87 ineffective, since the drum 69 and thus the cam face 99 will slightly lead the driving pin 77 which is tracked by the servo positioning drive 5.

Claims

CLAINS:

1. Actuating device for a motor vehicle clutch, comprising a carrier part (17), an output member (29, 31, 35) guided for movement on and relative to the carrier part (17) for actua tion of the clutch and also comprising a servo positioning drive (5) for driving the output member (29, 31, 35), charac terised in that there are on the carrier part (17), guided for movement relative to each other and to the output member (29, 31, 35), two input members-(41, 69), of which a first in put member (41) is movable via the servo positioning drive (5) and of which a second input member (69) is movable via an operating device (1) and in that the input members (41, 69) comprise driving abutments (51, 81) while the output member (29, 31, 35) comprises, associated with the driving abutments (51, 81), counter-abutments (59, 61, 77), via which the input members (41, 69) drive the output member (29, 31, 35) indepen dently of each other for the clutch positioning movement.

2. Actuating device according to Claim 1, characterised in that an interlocking device (87) locks the output member (29, 31, 35) in its position relative to the carrier part (17) in which the clutch is fully disengaged and in that the second in put member (69) has a control surface (99)which releases the inter locking device (87) in that position of the second input member (69) which is associated with a disengaged clutch.

3. Actuating device according to Claim 1 or 2, characterised in that the input members (41, 69) and the output member (29, 31, 35) are constructed as axially adjacently disposed d i s c parts which are rotatable in respect of each other about a common axis of rotation and in that the driving abutments or counter abutments take the form of cut-outs (53, 55, 79) shaped like segments of a circle and which are concentric of the axis of rotation and which have axial driving pins (51, 77) which en gage into the cut-outs (53, 55, 79).

4. Actuating device according to Claim 3, characterised in that the driving abutment of the first input member (41) is con structed as a driving pin (51) while the counter abutment of the output member (29, 31, 35) is constructed as a cut-out (53, 55).

5. Actuating device according to Claim 3 or 4, characterised in that the driving abutment of the second input member (69) is constructed as a cut-out (79) while the counter abutment of the output member (29, 31, 350 is constructed as a driving pin (77).

6. Actuating device according to Claim 5 in conjunction with Claim 2, characterised in that the interlocking device (87) comprises a catch (89) co-operating with the driving pin (77) of the output member (29, 31, 350 and guided resiliently on the carrier part (17) and in that the control surface is con stituted by, shaped like a segment of a circle, a cam path (99) co-operating with the catch (89) and curved around the axis of rotation.

7. Actuating device according to Claim 6, characterised in that the catch (89) is disposed on that side of the second input member (69) which is axially remote from the output member (29, 31, 35) and co-operates in axially resilient manner with the driving pin (77) of the output member (29, 31, 35).

8. Actuating device according to one of Claims 3 to 7, characteri sed in that the first input member (41) is constructed as a gearwheel (41) mounted to rotate on a shaft (23) and meshing with a driving gearwheel, particularly a driving worm (45) of the servo positioning drive (5), and in that the output member (29, 31, 35) comprises, disposed on axially opposite sides of the gearwheel (41) and connected in non-rotatable manner with each other, two discs (29, 31) both of which are coupled to the gearwheel (41) via driving abutment/counter abutment connections (51, 53, 55).

9. Actuating device according to Claim 8, characterised in that the gearwheel is constructed as a segmental gearwheel (41) and in that in the gap (75) between the segments of the gear wheel (41) there is disposed a clutch actuating push rod (35) which is situated axially between the two discs (29, 31), being articulatingly connected to the two discs (29, 31).

10. Actuating device according to one of Claims 3 to 9, characteri sed in that the second input member is constructed as a rope drum (69).

11. Actuating device according to one of Claims 3 to 10, charac terised in that the shaft (23) is rotatably mounted in the carrier part (17) and is non-rotatably connected to the output member (29, 31, 35) and also with an actual value transmitter (13) of the servo positioning drive (5) which detects the angular position of the shaft (23).

12. Actuating device for a motor vehicle clutch substantially as described tith reference to the accompanying drawings.