Clutch actuator with automatic wear compensation

Abstract

A clutch actuator transmitting a disengaging force to a clutch disengaging device of a includes an actuating element which receives the disengaging force, and a piston rod for transmitting the disengaging force from the actuating element to the disengaging device. The piston rod bears against an actuating element connection region such that the piston rod is movable towards the connection region by the reaction force of the clutch. The positioning of the connection region and the piston rod relative to each other due to the movement can be fixed by applying the disengaging force to the actuating element. The actuating element at least partly deflects the disengaging force, producing a normal force and/or a radial force acting between the connection region and the piston rod. The normal force and/or the radial force fixes the position of the connection region and the piston rod relative to each other.

Claims

1. A clutch actuator for transmitting a disengaging force to a disengaging device of a clutch, comprising: an actuating element that is subjected to the disengaging force; and a piston rod for transmitting the disengaging force from the actuating element to the disengaging device, wherein the piston rod is mounted against a connecting region of the actuating element so that the piston rod is movable against the connecting region by a clutch reaction force of the clutch, the positioning of the connecting region and the piston rod relative to one another is fixed during application of the disengaging force, the actuating element is configured for the at least partial deflection of the disengaging force into a normal force and/or radial force that is effective between the connecting region and the piston rod, wherein said normal force and/or radial force fixes the positioning of the connecting region and the piston rod relative to one another.

2. The clutch actuator as claimed in claim 1, an outer circumference of the piston rod is slideable against an inner circumference of the connecting region.

3. The clutch actuator as claimed in claim 2, wherein the piston rod has an external transmission thread, which engages in an internal transmission thread on the connecting region.

4. The clutch actuator as claimed in claim 1, wherein the piston rod has an external transmission thread, which engages in an internal transmission thread on the connecting region.

5. The clutch actuator as claimed in claim 1, further comprising: a preload force device for exerting a preload force that is effective between the piston rod and the actuating element, said preload force counteracting the clutch reaction force of the clutch, is provided.

6. The clutch actuator as claimed in claim 1, wherein the normal force or the radial force fixes the positioning of connecting region and piston rod relative to one another via a self-amplifying frictional connection.

7. The clutch actuator as claimed in claim 1, wherein the connecting region is mounted on the actuating element so that said connecting region can be radially pivoted in the direction of the piston rod through a linear movement of the actuating element in the axial direction of the piston rod.

8. The clutch actuator as claimed in claim 1, wherein the connecting region is designed as a connecting element and/or is part of a connecting element, wherein said connecting element is fixable against a stop on the actuating element through the clutch reaction force and/or through the preload force.

9. The clutch actuator as claimed in claim 1, wherein the connecting region is configured as a connecting element, which is pivotably mounted on the actuating element.

10. The clutch actuator as claimed in claim 1, wherein an end stop position is provided, with which the actuating element is in contact when the clutch is engaged.

11. The clutch actuator as claimed in claim 10, further comprising: means for reducing and/or eliminating the normal force and/or the radial force are provided, said means being actuatable by bringing the actuating element into the end stop position.

12. The clutch actuator as claimed in claim 11, wherein the means for reducing and/or eliminating the normal force and/or the radial force is a connecting element, which is pivotably mounted on the actuating element.

13. The clutch actuator as claimed in claim 1, wherein the actuating element is a piston, which is displaceably mounted in a housing and, in said housing, closes off a pressure chamber, so that the actuating element is subjected to the disengaging force by introducing a pressure medium into the pressure chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of an exemplary embodiment of the clutch actuator according to the invention with mutually engaging transmission threads on the piston rod and connecting region.

(2) FIG. 2 is a schematic diagram of an exemplary embodiment of the clutch actuator according to the invention without threads on the piston rod and connecting region.

DETAILED DESCRIPTION OF THE DRAWINGS

(3) FIG. 1 shows a first exemplary embodiment of the clutch actuator 100 according to the invention. An essential feature here is that a functional integration of the two partial functions length compensation and blocking of length compensation into the components connecting element 14 and piston rod 15 takes place, specifically exactly at the point at which these two components are in contact with one another anyway for the purpose of the mutual relative movement.

(4) The mode of operation in this case presents itself as follows. The actuating element 13 designed as a piston is radially mounted in a housing 1 and sealed in the direction of a resulting pressure chamber. The housing 1 with its cover 12 and the piston 13 enclose a pressure chamber 11. By means of auxiliary energy, which is supplied to the pressure chamber 11 in the form of a pressure medium, the disengaging force F.sub.A is exerted on the piston 13. In contrast with the prior art, this force positively supports itself on the connecting element 14 designed as a clamping element. On its inner circumference 32, the clamping element 14 has an internal transmission thread 35, with which it is in positive contact with a corresponding external transmission thread 34 on the outer circumference 30 of the piston rod 15. Furthermore, there is a frictional contact between clamping element 14 and piston rod 15 in the radial direction. This frictional connection can, but does not necessarily have to, be present even in the unactuated state of the clutch actuator 100.

(5) Upon actuation of the clutch actuator 100, a radial force F.sub.R that is proportional to the actuator force is created on the clamping element 14, which ensures a correspondingly self-amplifying frictional connection between clamping element 14 and piston rod 15 and prevents a length compensation between piston 13 and piston rod 15 during the actuation of the clutch actuator 100. The piston rod 15 furthermore transmits the actuator force or the corresponding travel of the piston 13 to the clutch 101 via a disengagement lever 22.

(6) In the unactuated state of the clutch actuator 100, the clutch reaction force F.sub.K is directed to the piston rod 15 via the disengagement lever 22. The preload spring 6 engaging there slides the piston 13 in the direction of the lid 12 until the clamping element 14 lies against the end stop position 40 arranged on the lid 12 in such a manner that the radial force F.sub.R and thus the frictional connection in the radial direction between clamping element 14 and piston rod 15 is canceled. To this end, the components are designed in such a manner that the force exerted from the end stop position on the clamping element 14 leads to a radial opening or unloading of the corresponding functional surface on the clamping element 14.

(7) The clutch 101 comprises a clutch disk 20a assigned to the motor with a frictional lining 20b and a clutch disk 21a assigned to the transmission with a frictional lining 21b. The two clutch disks 20a and 21a are pressed against one another by the resetting spring 23, which exerts the clutch reaction force F.sub.K. They can be separated from one another or transferred to a state of slipping relative to one another by moving the disengagement lever 22 against the force of the resetting spring 23.

(8) A kinematic change originating from the clutch 101 through lining wear, which requires a length compensation between piston 13 and piston rod 15, can thus take place via the transmission thread of the components clamping element 14 and piston rod 15. During the actuation phases, by contrast, a blocking of the readjusting mechanism is ensured through the frictional connection between clamping element 14 and piston rod 15 by virtue of the fact that a length compensation between piston 13 and piston rod 15 via the transmission thread in the components clamping element 14 and piston rod 15 is prevented.

(9) The shaft 41 assigned to the motor and the shaft 42 assigned to the transmission, between which the clutch 101 establishes a non-positive connection in the closed state, are offset against the longitudinal axis of the disengagement lever 22 and the piston rod 15. To this end, the disengagement lever 22 does not actuate the clutch 101 directly but by means of a lever linkage, which comprises the elements 22a and 22f. The disengagement lever 22 is pivotably mounted against the element 22a via a joint 22d. At its other end, the element 22a is pivotably mounted against a fixed point 26 with a joint 22b. The element 22f is pivotably mounted on the element 22a with a further joint 22c. The element 22f is articulated on the clutch disk 21a at the point 22e. The lever linkage offsets not only the axis in which the disengaging force F.sub.A acts, but amplifies this force F.sub.A through the lever action to form a force F.sub.A. The distance, by which the piston rod 15 has to be moved for actuating the clutch is enlarged with the same lever ratio.

(10) FIG. 2 shows a further exemplary embodiment of the clutch actuator 100 according to the invention. An essential feature besides a functional integration of the two partial functions length compensation and blocking of length compensation in the components clamping element 24 and piston rod 25, as already shown in FIG. 1 for the clamping element 14, in this case is that transmission threads 34, 35 for the length compensation become obsolete. As a result, the complexity of the clutch actuator 100 is further reduced. The mode of operation in this case presents itself as follows. The actuating element 13 designed as a piston is radially mounted in a housing 1 and sealed in the direction of a resulting pressure chamber 11. The pressure chamber 11 is enclosed by the components housing 1, lid 12 of the housing 1 and piston 13. The disengaging force F.sub.A is exerted on the piston 13 by means of auxiliary energy, which is fed to the pressure chamber 11 in the form of a pressure medium. Analogously to the exemplary embodiment shown in FIG. 1, this force positively supports itself on the clamping element 24. A frictional contact exists in the radial direction between clamping element 24 and piston rod 25. This frictional connection can, but does not not necessarily have to, be present even in the unactuated state of the clutch actuator 100.

(11) On actuating the clutch actuator 100, a radial force F.sub.R that is proportional to the actuator force develops on the clamping element 24, which ensures a corresponding self-amplifying frictional connection between clamping element 24 and piston rod 25 and prevents a length compensation between piston 13 and piston rod 25 during the actuation of the clutch actuator 100. The piston rod 25 furthermore, transmits the actuator force or the corresponding travel of the piston 13 to the clutch 101 via a disengagement lever 22.

(12) In the unactuated state of the clutch actuator 100, the clutch reaction force F.sub.K is directed to the piston rod 25 via the disengagement lever 22. The preload spring 6 engaging there slides the piston 13 in the direction of the lid 12 until the clamping element 24 lies against the end stop position arranged on the lid 12 in such a manner that the radial force F.sub.R and thus the frictional connection in the radial direction between clamping element 24 and piston rod 25 is canceled. To this end, the components are designed in such a manner that the force exerted on the clamping element 24 from the end stop position leads to a radial opening or unloading of the corresponding functional surface on the clamping element 24. The smooth outer circumference 31 of the piston rod 25 can then freely slide against the smooth outer circumference 33 of the connecting element 24 corresponding thereto for the length compensation.

(13) The clutch 101 is the same as shown in the exemplary embodiment in FIG. 1. It is also actuated in the same manner by the disengagement lever 22 via the lever linkage consisting of the elements 22a and 22f so that the axes of the shaft 41 assigned to the motor and the shaft 42 assigned to the transmission in turn are offset against the longitudinal axis of the disengagement lever 22 and of the piston rod 25. A kinematic change originating from the clutch by way of lining wear, which requires a length compensation between piston (13) and piston rod (25), can take place between the components clamping element 24 and piston rod 25, which slide against one another with their respective functional surfaces. During the actuation phases, by contrast, a blocking of the readjusting mechanism is ensured through the frictional connection between clamping element 24 and piston rod 25 by virtue of the fact that a length compensation between piston 13 and piston rod 25 is prevented through the frictional connection between the components clamping element 24 and piston rod 25. Compared with the exemplary embodiment shown in FIG. 1, a higher radial force F.sub.R is needed since a rotation of two components provided with transmission threads against one another can be more easily blocked than a sliding of two components against one another. With the same disengaging force F.sub.A, the higher radial force F.sub.R can be provided by a design of the clamping element 24 that is adapted relative to the clamping element 14.

LIST OF REFERENCE NUMERALS

(14) 1 Housing 11 Pressure chamber in the housing 1 12 Lid of the housing 1 13 Actuating element, piston 14, 24 Connecting elements, clamping elements 15, 25 Piston rods 6 Preload spring 20a, 21a Clutch disks of the clutch 101 20b, 21b Friction linings of the clutch disks 20a, 21a 22 Disengagement lever of the clutch 101 22a, 22f Elements of the lever linkage for the clutch actuation 22b, 22c, 22d Joints 22e Articulation point on the clutch disk 21a 23 Resetting spring of the clutch 101 for clutch reaction force F.sub.K 26 Fixed bearing point for element 22a 30 Outer circumference of the piston rod 15 31 Outer circumference of the piston rod 25 32 Inner circumference of the connecting region 14 33 Inner circumference of the connecting region 15 34 External transmission thread of the piston rod 15 35 Internal transmission thread of the connecting element 14 40 End stop position for the actuating element 13 41 Shaft assigned to the motor 42 Shaft assigned to the transmission 100 Clutch actuator 101 Clutch F.sub.A Disengaging force F.sub.A Disengaging force F.sub.A amplified by lever action F.sub.F Preload force F.sub.K Clutch reaction force F.sub.N Normal force F.sub.R Radial force

(15) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.