Ball screw drive for an actuator group

1 . A ball screw drive for an actuator assembly of a vehicle brake, comprising,

a rotatably mounted recirculating ball screw spindle, on which a spindle nut open on one side is mounted,

wherein at least one thread groove is formed on a circumferential surface of the recirculating ball screw spindle, and a corresponding thread groove is formed on an inner surface of the spindle nut, wherein a multiplicity of balls is guided in the thread grooves in such a way that rotation of the recirculating ball screw spindle brings about axial movement of the spindle nut along a rotational axis of the recirculating ball screw spindle,

wherein the spindle nut is manufactured from rolling bearing steel or from C steel and is hardened at least in a region of the threaded groove; and

wherein the spindle nut has an anti-corrosion coating on an outside surface, the coating being applied to at least an end face and a region of a circumferential wall adjoining the end face,

wherein the anti-corrosion coating is absent from at least one axial end region of the spindle nut remote from an end face that is configured to engage a brake pad, and wherein the anti-corrosion coating is configured to resist environmental exposure in a brake caliper gap.

2 . A brake piston for a vehicle brake which comprises a ball screw drive according to claim 1 , wherein the spindle nut of the ball screw drive forms the brake piston.

3 . The ball screw drive according to claim 1 , wherein the circumferential wall of the spindle nut is completely coated with the anti-corrosion coating except for a portion of the axial end region that defines the open side of the spindle nut subjected to surface pressure.

4 . The ball screw drive according to claim 3 , wherein the spindle nut is hardened at least in a region of the thread groove.

5 . The ball screw drive according to claim 1 , wherein the spindle nut is fully hardened and tempered, bainitized or inductively hardened.

6 . The ball screw drive according to claim 5 , wherein a circumferential wall of the spindle nut is completely coated with the anti-corrosion coating except for the axial end region subjected to surface pressure.

7 . A ball screw drive for an actuator assembly of a vehicle brake, comprising, a rotatably mounted recirculating ball screw spindle, on which a spindle nut open on one side is mounted,

wherein at least one thread groove is formed on a circumferential surface of the recirculating ball screw spindle, and a corresponding thread groove is formed on an inner surface of the spindle nut, wherein a multiplicity of balls is guided in the thread grooves in such a way that rotation of the recirculating ball screw spindle brings about axial movement of the spindle nut along a rotational axis of the recirculating ball screw spindle,

wherein the spindle nut has an anti-corrosion coating applied directly to an exterior surface of the spindle nut, the coating being limited to regions of the spindle nut exposed to the environment and excluded from a region remote from an end face of the spindle nut that is configured to engage a brake pad, and wherein the spindle nut is at least partially exposed to the environment during operation.

8 . The ball screw drive according to claim 7 , wherein a circumferential wall of the spindle nut is completely coated with the anti-corrosion coating except for an end face opposite the end of the spindle nut that is configured to engage the brake pad.

9 . The ball screw drive according to claim 7 , wherein the spindle nut is hardened at least in a region of the thread groove.

10 . The ball screw drive according to claim 7 , wherein the spindle nut has an anti-corrosion coating on at least on the end face configured to engage the brake pad and in a region of a circumferential wall adjoining the end face while being free of the anti-corrosion coating remaining regions.