Transmission mechanism for actuating a friction clutch

Abstract

A transmission mechanism for actuating a friction clutch, which can be disengaged against a spring force and is arranged between an internal combustion engine and a manual transmission, includes two lockable elements that are movable toward one another longitudinally to automatically change the length and compensate for clutch wear. The first element consists of a spindle which is coupled to a non-rotatable component of a disengagement mechanism of the friction clutch in a rotationally fixed and axially displaceable manner and has a steep-pitch external thread. The second element consists of a nut having a steep-pitch internal thread into which the spindle can be screwed, the pitch of the steep-pitch thread being dimensioned in such a way that no self-locking can occur between the two elements.

Claims

1. A transmission mechanism (1) for actuating a friction clutch which can be disengaged against a spring force and is arranged between an internal combustion engine and a manual transmission, the transmission mechanism comprising: a first lockable element (16) and a second lockable element (11) configured to be moved toward one another longitudinally to automatically change a length and to compensate for clutch wear, wherein the first lockable element is a spindle (16) coupled to a non-rotatable component of a disengagement mechanism of the friction clutch in a rotationally fixed and axially movable manner and has a region (18) with a steep-pitch external thread (19), wherein the second lockable element is of a nut (11) having a steep-pitch internal thread (15) complementary to the steep-pitch external thread (19) of the spindle (16), wherein the internal and external steep-pitch threads (15, 19) have a pitch dimensioned in such a way that no self-locking can occur between the two elements (11, 16), wherein the nut (11) is arranged in a hollow casing (2) immovably fixed to a controlling element of a pneumatic, hydraulic or electromechanical clutch actuator, wherein the casing (2) has an axially parallel multi-toothed profile (5) directed radially inwards over a length which substantially corresponds to an actuation path (S.sub.B) of the friction clutch, wherein the nut (11) interacts with the multi-toothed profile (5) in a non-rotatable manner via a polygonal collar (12) which protrudes radially beyond a cylindrical region (14) of the nut (11) when the friction clutch is disengaged, wherein the casing (2) has a free region (4) without a multi-toothed profile (5) at an end of the actuation path (S.sub.B) which corresponds to an engaged state of the friction clutch, wherein the polygonal collar (12) of the nut (11) is freely rotatable in the free region (4) when a spring force is applied to the polygonal collar (12) while the friction clutch is engaged, and is rotatable relative to the spindle (16) toward an end fitting (7) on the casing (2) by an adjustable wear compensation path (S.sub.V) corresponding to a change in length as a result of clutch wear that has occurred.

2. The transmission mechanism as claimed in claim 1 further comprising a tappet (21) for disengaging the friction clutch over the actuation path (S.sub.B) as a result of axial displacement in a non-rotational manner of the nut (11) in the casing (2), wherein the tappet (21) is operatively connected to the nut (11) and to the disengagement mechanism of the clutch.

3. The transmission mechanism as claimed in claim 2 wherein the spindle (16), has a stop flange at an end of the region (18) with the steep-pitch external thread (19), wherein the stop flange (20) overlaps, at least partially, with an end face of the nut (11), further comprising a bias spring (23) arranged in an internal bore (22) in the tappet (21) supported at one end by the stop flange and supported at an opposite end on a tappet cover (24).

4. The transmission mechanism as claimed in claim 2, further comprising a positioning spring (10) arranged between a casing cover (8) of the casing (2) and the nut (11), the casing cover (8) being remote from the tappet (21) and from the polygonal collar (12) of the nut (11).

5. The transmission mechanism as claimed in claim 3, wherein the length of the internal bore (22) in the tappet (21) is at least equal to a maximum adjustable wear compensation path (S.sub.V) of the friction clutch plus a block length of the bias spring (23) and a thickness of the stop flange (20) on the spindle (16).

6. The transmission mechanism as claimed in claim 1, further comprising a thrust bearing (6) in the form of a slide bearing, ball bearing, or needle bearing is arranged adjacent the polygonal collar.

7. The transmission mechanism as claimed in claim 6, wherein the thrust bearing is arranged in the free region (4) of the casing (2) between the polygonal collar (12) of the nut (11) and the inner flange (7) of the casing (2).

8. The transmission mechanism as claimed in claim 1, wherein the transmission mechanism (1) is modularly formed as a unit to be exchangeably arranged between the pneumatic, hydraulic or electromechanical clutch actuator and the disengagement mechanism of the friction clutch.

9. A motor vehicle or rail vehicle, comprising the manual transmission, the internal combustion engine, and the transmission mechanism (1) as claimed in claim 1, wherein the transmission mechanism is arranged between the internal combustion engine and the manual transmission.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings,

(2) FIG. 1 is a longitudinal sectional view of the transmission mechanism according to the invention in the unactuated state, even if no wear has yet occurred in the friction clutch,

(3) FIG. 2 is a longitudinal sectional view through the transmission mechanism according to FIG. 1 with the adjusted, maximum possible wear compensation path, and

(4) FIG. 3 is a schematic, end-face plan view of a nut arranged in a casing of the transmission mechanism according to FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) The transmission mechanism 1 shown in FIG. 1 for actuating a friction clutch (not visible) which can be disengaged against a spring force and is arranged between an internal combustion engine and a manual transmission, comprises two lockable elements which can be moved toward one another longitudinally, in particular a nut 11 and a spindle 16, which are used to automatically change the length in the event of clutch wear. The first element consists of a spindle 16 which is coupled to a non-rotatable component of a disengagement mechanism of the friction clutch in a rotationally fixed and axially displaceable manner and has a steep-pitch external thread 19 which can be screwed into a steep-pitch internal thread 15, which is complementary thereto, of the second element consisting of a nut 11. In this case, the pitch of the two steep-pitch threads 15, 19 is dimensioned in such a way that no self-locking can occur between these two elements, namely the nut 11 and the spindle 16. At the axial end thereof which is remote from the nut, the spindle 16 comprises a non-circular end region 17 which is preferably polygonal and is arranged in a non-rotational, axially displaceable manner in a non-rotating actuator assembly of the friction clutch. At the opposite axial end of the spindle 16, that is to say at the end of the region 18 which is remote from the cover and comprises the steep-pitch external thread 19, a stop flange 20 is arranged, which overlaps the nut 11 radially in part at the associated axial end thereof.

(6) The nut 11 is arranged in a casing 2 which is connected to a housing (not shown) of a clutch actuator. The casing 2 is hollow cylindrical and comprises, at one axial end thereof, a clearance 3 delimited by a casing cover 8, through the opening of which the spindle 16 is guided into the casing 2. Over a length S.sub.B which substantially corresponds to the actuation path of the friction clutch, the wall of this clearance 3 has an axial multi-toothed profile 5 which is used to secure the nut 11 against rotation in the casing 2. For this purpose, the nut 11 comprises, at one axial end, a radially outwardly protruding polygonal collar 12, which is preferably in the form of a hexagonal collar.

(7) This polygonal collar 12, which has a shorter axial length in comparison with the length of the nut 11, in the case of an unactuated transmission mechanism, ends up in the end position shown in FIG. 1 in a geometrically approximately annular-groove-shaped region 4 which is free from the multi-toothed profile 5, in which region the nut 11, together with the polygonal collar 12 thereof, can freely rotate. This free region 4 is axially delimited by a radially inwardly projecting inner flange 7 on the casing 2, through which a hollow tappet 21 is guided. On this tappet 21, the nut 11 is axially supported in the upper position thereof, and the tappet 21 is axially displaceable by means of a clutch actuator (not shown).

(8) Between the polygonal collar 12 of the nut 11 and the inner flange 7 of the casing 2, a thrust bearing 6 in the form of a slide, ball or needle bearing is formed or arranged to reduce the friction between the tappet 21 and the nut 11 when the nut rotates by a corresponding amount relative to the spindle 16 under the effect of the axial spring force of a positioning spring 10 in the form of a helical compression spring to compensate for the clutch wear. The positioning spring 10 is arranged in the clearance 3 of the casing 2, radially outwardly encompasses the nut 11 in the cylindrical region 14 thereof, and the one axial end thereof is supported on the lower face, which is remote from the tappet, of the polygonal collar 12 of the nut 2. By means of the other axial end thereof, the positioning spring 10 is supported on an insert 9 which is inserted in the clearance 3 of the casing 2 and, in the portion thereof which is close to the tappet, has the axial multi-toothed profile 5. The casing 2 is closed at the end remote from the tappet by a casing cover 8.

(9) The polygonal collar 12 is provided with insertion bevels 13 so that, when the nut 11 is displaced by means of the tappet 21 toward the casing cover 8, at least one point of the polygonal collar 12 can be inserted in the multi-toothed profile 5 more easily. As a result, a rotationally fixed connection between the nut 11 and the casing 2 is ensured when dealing with an actuation path S.sub.B during the disengagement of the friction clutch. Since, in a rotationally fixed arrangement of the friction clutch, the spindle 16 is also held in a rotationally fixed manner, the position of the nut 11 relative to the spindle 16 cannot change during the actuation of the friction clutch.

(10) The tappet 21 comprises an internal bore 22 for guiding the stop flange 20 of the spindle 16 and for guiding a bias spring 23 in the form of a helical compression spring which is axially supported on the stop flange 20 of the spindle 16 and on a tappet cover 24.

(11) FIG. 2 shows how far the spindle 16 can screw through the nut 11 until the maximum adjustable wear compensation path S.sub.V is completed.

(12) To additionally reduce the internal friction in the transmission mechanism when adjusting the clutch wear, additional thrust bearings in the form of a slide, ball or needle bearing can be formed or arranged between the polygonal collar 12 on the nut 11 and the stop flange 20 on the spindle 16 and between the polygonal collar 12 on the nut 11 and the one axial end of the positioning spring 10. Furthermore, the steep-pitch thread on the nut 11 and on the spindle 16 can be in the form of a ball thread.

(13) The transmission mechanism 1 according to the invention ensures the required wear compensation of the friction clutch by means of a non-self-locking screw connection combination of the nut 11 and the spindle 16 which, in an unactuated state, brings about a length compensation by rotating the nut 11 relative to the spindle 16 and, in an actuated state, is a pressure-tight and rotationally fixed connection, since the nut 11 can then be displaced while secured against rotation by the engagement of the polygonal collar 12 thereof in the multi-toothed profile 5 of the casing 2 (FIG. 3). In this case, the spindle 16 cannot rotate relative to the nut 11, since this spindle is axially guided in only a displaceable manner through the non-circular end region 17 of the spindle 16 in the non-rotatable component of the disengagement mechanism.

(14) The nut 11 is guided in the casing 2 in such a way that, in the unactuated state of the clutch actuator, the nut can freely rotate in the free, annular-channel-type region 4 of the casing 2 and, in the actuated state of the clutch actuator, is prevented from rotating by the engagement of the polygonal collar 12 of the nut 11 in the axial multi-toothed profile 5 of the casing 2. In the unactuated state of the transmission mechanism 1, the force F.sub.K applied by the clutch mechanism can axially displace the spindle 16, since the force is not impeded from doing so by the nut 11. As soon as the spindle 16 has been axially displaced far enough that, at the pressure point of the clutch actuation, an equilibrium of forces with the spring force F.sub.V of the bias spring 23 in the tappet 21 is produced, the maximum adjustment path in this situation is completed. In the unactuated state of the transmission mechanism 1, the ideal length thereof can thus always be readjusted, the length compensation being able to take place in both directions. If the clutch actuator is then actuated again, the nut 11 is once again displaced into the rotationally secured region of the multi-toothed profile 5 of the casing 2, and, in this case, the nut 11 carries along the spindle 16 without changing the adjustment path previously taken into consideration.