초록 ▼

The present invention relates to a motor vehicle brake system, having at least one first and at least one second electromechanical wheel brake (10), which each comprise an electric actuator for generating an actuating force and a self-boosting device for automatically boosting the actuating force ge

The present invention relates to a motor vehicle brake system, having at least one first and at least one second electromechanical wheel brake (10), which each comprise an electric actuator for generating an actuating force and a self-boosting device for automatically boosting the actuating force generated by the actuator in order to press a friction element against a rotatable component (14) of the wheel brake (10) that is to be braked, wherein each self-boosting device comprises a wedge (18), which is supported against an associated abutment (22) and has at least one wedge face (20, 20') disposed at an angle of slope (α). In order to realize a parking brake function, the self-boosting device of the first wheel brake comprises at least one wedge face (20), which is used to boost the force in brake operations during forward travel, and the self-boosting device of the second wheel brake comprises at least one wedge face (20'), which is used to boost the force in braking operations during reverse travel. In many embodiments, the angle of slope (α) of the said wedge faces (20, 20') is so selected that the wheel brakes (10) in any case with normally prevailing coefficients of friction μ are self-locking. In the parking brake function the friction element of the first wheel brake, by utilizing the wedge face (20) used to boost the force in braking operations during forward travel, and the friction element of the second wheel brake, by utilizing the wedge face (20') used to boost the force in braking operations during reverse travel, are clamped against the component of the wheel brake (10) that is to be braked. The invention also relates to an electromechanical brake for such a motor vehicle brake system.

대표청구항 ▼

This invention claimed is: 1. A motor vehicle brake system, comprising: at least one first electromechanical wheel brake; and at least one second electromechanical wheel brake (10), each first and second electromechanical wheel brake comprising an electric actuator for generating an actuating forc

This invention claimed is: 1. A motor vehicle brake system, comprising: at least one first electromechanical wheel brake; and at least one second electromechanical wheel brake (10), each first and second electromechanical wheel brake comprising an electric actuator for generating an actuating force, and a self-boosting device for automatically boosting the actuating force generated by the actuator to thereby press a friction element against a rotatable component (14) of the wheel brake (10), wherein each self-boosting device comprises a wedge (18), which is supported against an associated abutment (22) and has at least one wedge face (20, 20') disposed at an angle of slope (α) , the self-boosting device of the first wheel brake comprising at least one wedge face (20), which is used to boost the force in braking operations during forward travel, the self-boosting device of the second wheel brake comprising at least one wedge face (20'), which is used to boost the force in braking operations during reverse travel, and wherein the friction element of the first wheel brake, by utilizing the wedge face (20) used to boost the force in braking operations during forward travel, and the friction element of the second wheel brake, by utilizing the wedge face (20') used to boost the force in braking operations during reverse travel, are clamped against the rotatable component of the wheel brake (10) to function as a parking brake. 2. A motor vehicle brake system according to claim 1, wherein the angle of slope (α) of the said wedge faces (20, 20') is selected in such a way that the wheel brakes (10) in any case with normally prevailing coefficients of friction μ are self-locking. 3. A motor Meter vehicle brake system according to claim 2, wherein a distance-controlled application of each wheel brake (10) participating in the parking brake function initially occurs and is followed by a zero-force correction of the actuator of each wheel brake (10) participating in the parking brake function. 4. A motor vehicle brake system according to claim 3 wherein the distance-controlled brake application is effected over a predetermined infeed distance up to a predetermined brake application force and is terminated when either the predetermined infeed distance or the predetermined brake application force has been reached, and that the zero-force correction of the actuator is effected only when the predetermined infeed distance has been reached. 5. A motor vehicle brake system according to claim 4, wherein the predetermined brake application force is a fraction of a maximum actuator force, preferably 30% of the maximum actuator force. 6. A motor vehicle brake system according to claim 3, wherein a predetermined brake application force is effected after a predetermined time interval and/or in dependence upon a temperature of brake components relevant to the brake application. 7. A motor vehicle brake system according to claim 3, wherein a further zero-force correction of the actuator of each wheel brake (10) participating in the parking brake function is effected after the distance-controlled brake application external forces acting upon the vehicle have brought about an automatic further application of the wheel brake. 8. A motor vehicle brake system according to claim 1, wherein the actuator is lockable, the system further comprising spring-elastic means between the actuator, and the associated friction element of the wheel brake (10), wherein the spring-elastic means exert an application force upon the friction element in a parking brake position. 9. A motor vehicle brake system according to claim 8, wherein the spring-elastic means act upon a wedge arrangement of the self-boosting device that comprises the wedge face (20, 20') and wherein the spring-elastic means are supported indirectly or directly against the locked actuator. 10. A motor vehicle brake system according to claim 8, wherein the spring-elastic means are formed by a helical spring. 11. A motor vehicle brake system according to claim 1, wherein an activation of the parking brake function is effected automatically on gradients after attainment of a stationary state of the vehicle from forward travel in order to combat a backward rolling of the vehicle. 12. A motor vehicle brake system according to claim 11, wherein activation of the parking brake function is effected only after a service brake of the vehicle has been released. 13. A motor vehicle brake system according to claim 12, wherein activation of the parking brake function is not effected until a predetermined length of time after release of the service brake. 14. A motor vehicle brake system according to claim 11, wherein activation of the parking brake function on gradients is effected automatically after attainment of the stationary state of the vehicle also from reverse travel. 15. A motor vehicle brake system according to claim 14, wherein activation of the parking brake function is effected only when no gear of a transmission of the vehicle is engaged. 16. A motor vehicle brake system according to claim 11, wherein activation of the parking brake function is effected only when a predetermined friction torque in the backward rolling direction has been exceeded. 17. A motor vehicle brake system according to claim 1, wherein activation of the parking brake function is effected automatically when an engine of the vehicle is switched off. 18. An electromechanical wheel brake (10) for use in a motor vehicle brake system, comprising: an electric actuator for generating an actuating force and a self-boosting device for automatically boosting the actuating force, generated by the actuator in order to press a friction element against a rotatable component (14) of the wheel brake (10), the self-boosting device comprising a wedge (18), which is supported against an associated abutment (22) and has at least one wedge face (20, 20') disposed at an angle of slope (α), the actuator comprising two drives (34, 34'), which are so designed that they may act in the same direction or in opposite directions upon the wedge (18) to enable a backlash-free actuation of the wedge (18) during service braking operation, and to give the wedge (18) a clearance in a parking brake position that enables an automatic further application of the wheel brake ( 10) by means of external forces acting upon the vehicle. 19. A wheel brake according to claim 18, wherein the angle of slope (α) is selected so that the wheel brake (10) in any case with normally prevailing coefficients of friction μ is self-locking. 20. A wheel brake according to claim 18, wherein the friction element comprises friction linings ( 16, 30) with a large jump in the coefficient of adhesion between static friction and sliding friction. 21. A wheel brake according to claim 18, wherein spring-elastic means are disposed between the actuator, which applies the wheel brake (10) in the parking brake function, and the associated friction element of the wheel brake ( 10), and the spring-elastic means exert an application force upon the friction element, and wherein the actuator is of a lockable design. 22. A wheel brake according to claim 21, wherein the actuator comprises an electric motor (36, 26') with a locking apparatus. 23. A wheel brake according to claim 21, wherein the actuator comprises a spindle mechanism of a self-locking design, which interacts with an electric motor (36, 36'). 24. A wheel brake according to claim 21, wherein the spring-elastic means act upon a wedge arrangement of the self-boosting device that comprises the wedge face (20, 20'), and the spring-elastic means are supported indirectly or directly against the locked actuator. 25. A wheel brake according to claim 21, wherein the spring-elastic means are formed by a helical spring, which exerts a pressure in the parking brake position. 26. A wheel brake according to claim 21, wherein the drives (34, 34') are designed as linear actuators which are workingly connected to the wedge (18) by a push rod (38, 38') having a push rod head (39, 39'), and wherein the spring-elastic means, which in the parking brake position exert an application force upon the friction element, are disposed between the push rod heads (39, 39'). 27. A wheel brake according to claim 21, wherein the drives (34, 34') are designed as linear actuators, which are workingly connected to the wedge (18) by a push rod (38, 38') having a push rod head (39, 39'), and wherein the spring-elastic means, which in the parking brake position exert an application force upon the friction element, are disposed between the push rod head (39) of the linear actuator that brings the wheel brake (20) into parking brake position and a wedge arrangement comprising the wedge (18). 28. A wheel brake according to claim 18, further comprising an additional separate drive for releasing the wheel brake (20) from the parking brake position. 29. A wheel brake according to claim 28, wherein the separate drive includes a worm gear. 30. A wheel brake according to claim 29, wherein the worm gear (46, 48) and the separate drive (44) are components of an adjusting device (42) for compensating friction lining wear.