Brake actuator unit, electromechanical brake, and spindle drive for a brake actuator unit

Abstract

The present disclosure relates to a brake actuator unit and to an electromechanical brake. The brake actuator unit has a spindle, which is driven in rotation by an electric motor, and a brake piston in the form of a spindle nut, which surrounds the spindle and is configured to press against a brake lining.

1 . The brake actuator unit for an electromechanical brake, comprising: a spindle, which is driven in rotation by an electric motor, and a brake piston in a form of a spindle nut, which surrounds the spindle and is configured to press against a brake lining. 
     
     
         2 . The brake actuator unit according to  claim 1 , wherein there is provided an axial bearing, which mounts the spindle axially, wherein the spindle is supported on the axial bearing on operation of the brake. 
     
     
         3 . The brake actuator unit according to  claim 2 , wherein there is provided a spindle drive having a core diameter of a thread of the brake piston for axial displaceability of the brake piston, wherein the core diameter of the thread is larger than an outside diameter of the axial bearing. 
     
     
         4 . The brake actuator unit according to  claim 3 , wherein the spindle has on a brake lining side a shaft portion which is thickened in cross-section and has a transmission thread of the spindle drive on an outer lateral surface, and a drive shaft prolongation of comparatively smaller cross-section, and a transition portion between the shaft portion and the drive shaft prolongation, wherein the axial bearing abuts a contact face provided by the transition portion. 
     
     
         5 . The brake actuator unit according to  claim 1 , wherein there is provided a brake housing which has a base and which accommodates the brake piston in its interior. 
     
     
         6 . The brake actuator unit according to  claim 2  wherein the axial bearing is supported on a base of a brake housing. 
     
     
         7 . The brake actuator unit according to  claim 6 , wherein an axial bearing washer is arranged axially between the axial bearing and the base of the brake housing and is pressed in the brake housing by frictional engagement and/or interlocking engagement in such a manner that it is secured against rotation. 
     
     
         8 . The brake actuator unit according to  claim 6  wherein a rotation lock is provided between the brake housing and the brake piston accommodated in a linearly displaceable manner therein, which rotation lock permits a linear displacement of the brake piston but prevents the brake piston from rotating relative to the brake housing. 
     
     
         9 . The brake actuator unit according to  claim 6 , wherein a gasket is provided on a brake lining side between the brake piston and the brake housing. 
     
     
         10 . The brake actuator unit according to  claim 1 , wherein a cup-shaped bushing is provided, wherein the cup-shaped bushing accommodates and mounts the brake piston, and the cup-shaped bushing is accommodated in the brake housing. 
     
     
         11 . The brake actuator unit according to  claim 1 , wherein the brake piston has on a brake lining side an end wall which presses against the brake lining when the brake is operated. 
     
     
         12 . The brake actuator unit according to  claim 3 , wherein the spindle drive has a ball screw. 
     
     
         13 . An electromechanical brake, having a brake actuator unit according to  claim 1 , wherein brake linings which can be moved towards one another, and an electric motor which is coupled in a torque-transmitting manner with the spindle. 
     
     
         14 . A spindle drive for a brake actuator unit according to  claim 1 , wherein a spindle to be driven, and a brake piston in a form of a spindle nut, which surrounds the spindle and is configured to press against a brake lining. 
     
     
         15 . A spindle drive according to  claim 14 , wherein the spindle has on the brake lining side a shaft portion which is thickened in cross-section and which has a transmission thread on an outer lateral surface, and a drive shaft prolongation of comparatively smaller cross-section, and a transition portion between the shaft portion and the drive shaft prolongation, wherein a spherical bearing contact face for an axial bearing is formed on the transition portion. 
     
     
         16 . The brake actuator unit according to  claim 4 , wherein there is provided a brake housing which has a base and which accommodates the brake piston in its interior. 
     
     
         17 . The brake actuator unit according to  claim 7 , wherein a rotation lock is provided between the brake housing and the brake piston accommodated in a linearly displaceable manner therein, which rotation lock permits a linear displacement of the brake piston but prevents the brake piston from rotating relative to the brake housing. 
     
     
         18 . The brake actuator unit according to  claim 9 , wherein the spindle drive has a ball screw.