Combined vehicle brake with electromechanically actuable parking brake
A combined vehicle brake which has a hydraulically actuable service brake and an electromechanically actuable parking brake device, a hydraulic service pressure space being delimited in a brake housing by a brake piston which can be acted upon by hydraulic pressure medium in order to execute service braking operations, so that the brake piston can be actuated along a piston longitudinal axis in order to achieve a braking action, and the parking brake device acting on the brake piston by a gear, in that the gear converts the rotational movement of an electromechanical actuator into a translational movement and causes an actuation of the brake piston in order to execute parking braking operations and holds the said brake piston in the actuated position, the gear having a threaded spindle and a threaded nut which are in contact with one another via a plurality of rolling bodies.
1. Combined vehicle brake comprising:
a hydraulically actuable service brake,
an electromechanically actuable parking brake device,
a hydraulic service pressure space being delimited in a brake housing by a brake piston which can be acted upon by hydraulic pressure medium in order to execute service braking operations, so that the brake piston can be actuated along a piston longitudinal axis in order to achieve a braking action,
said parking brake device acting on the brake piston by a gear, wherein the gear converts a rotational movement of an electromechanical actuator into a translational movement and causes an actuation of the brake piston in order to execute parking braking operations and holds the brake piston in the actuated position,
said gear having a threaded spindle that is rotatable and a threaded nut which are in contact with one another via a plurality of rolling bodies, wherein the rolling bodies are arranged so as to be movable to a limited extent in a thread flight between two stops, wherein rotational movement of the threaded spindle is transmitted via the rolling bodies to the threaded nut to execute a translational movement of the threaded nut,
a first spring element arranged between the rolling bodies and one of the two stops and allowing a slipping of the rolling bodies in an event of a load-free actuation of the gear and causing a rolling of the rolling bodies in an event of an actuation of the gear under load, and
one or more intermediate spring elements provided between the rolling bodies which reduces a frictional force of the rolling bodies with respect to one another when the gear is actuated,
wherein a second spring element is provided, which is arranged between the rolling bodies and the other of the two stops, and
wherein the threaded nut is not biased by a spring along the piston longitudinal axis toward the actuated position of the brake piston.
2. Combined vehicle brake according to claim 1 , wherein a ratio of a number of the rolling bodies to a number of the intermediate spring elements is constant.
3. Combined vehicle brake according to claim 1 , wherein the intermediate spring elements are distributed uniformly between the rolling bodies, in order to implement a uniform reduction in the frictional force of the rolling bodies with respect to one another.
4. Combined vehicle brake according to claim 1 , wherein the intermediate spring elements are helical compression springs.
5. Combined vehicle brake according to claim 1 , wherein the stops are connected non-positively to the threaded nut or are produced in one piece with the threaded nut.
6. Combined vehicle brake according to claim 1 , wherein the first stop has a bearing face for the first spring element, while the other stop has a bearing face for said second spring element.
7. Combined vehicle brake according to claim 1 , wherein each of the one or more intermediate spring elements is/are shorter than the first spring element.