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DE-102024210866-A1 - Electromechanical brake with flexible spindle

DE102024210866A1DE 102024210866 A1DE102024210866 A1DE 102024210866A1DE-102024210866-A1

Abstract

The invention relates to an electromechanical brake (10) for a motor vehicle. The electromechanical brake (10) comprises an electric motor (14) which rotates a spindle (22) of a spindle drive unit (26) arranged in a brake caliper housing (16), such that a spindle nut (38) is displaceable in an axial direction (40) of the brake caliper housing (16) for applying a braking force (F <sub>B</sub> ). An elastic section (46) is formed on the spindle (22) which has increased radial flexibility compared to the rest of the spindle (22), so that the spindle (22) undergoes radial bending when radial forces (F<sub> R</sub> ) are applied to the spindle nut (38).

Inventors

  • Matthias Greiner

Assignees

  • Robert Bosch Gesellschaft mit beschränkter Haftung

Dates

Publication Date
20260513
Application Date
20241113

Claims (8)

  1. Electromechanical brake (10) for a motor vehicle, comprising an electric motor (14) which rotationally drives a spindle (22) of a spindle drive unit (26) arranged in a brake caliper housing (16), such that a spindle nut (38) is displaceable in an axial direction (40) of the brake caliper housing (16) for applying a braking force (F B ), characterized in that an elastic area (46) is formed on the spindle (22) which has an increased radial flexibility compared to the rest of the spindle (22), so that the spindle (22) undergoes radial bending when radial forces (F R ) are applied to the spindle nut (38).
  2. Electromechanical brake (10) according to Claim 1 , characterized in that the elastic area (46) of the spindle (22) is formed with a reduced diameter ( DE ) compared to the rest of the spindle (22).
  3. Electromechanical brake (10) according to Claim 2 , characterized in that the elastic area (46) has a diameter ( DE ) that is 20-60% smaller than the rest of the spindle (22).
  4. Electromechanical brake (10) according to Claim 2 or 3 , characterized in that a rounded area (54) is formed in a transition area between reduced diameter ( DE ) and diameter ( DS ) of the remaining spindle (22).
  5. Electromechanical brake (10) according to one of the preceding claims, characterized in that the elastic area (46) is provided adjacent to a bearing point (30) of the spindle (22) and on a side of the spindle (22) facing the spindle nut (38).
  6. Electromechanical brake (10) according to one of the preceding claims, characterized in that at least one guide element (42) is arranged in the brake caliper housing (16), over which the spindle nut (38) is guided radially.
  7. Electromechanical brake (10) according to one of the preceding claims, characterized in that the spindle drive unit (26) is a ball screw drive.
  8. Motor vehicle comprising an electromechanical brake (10) according to one of the preceding claims.

Description

The present invention relates to an electromechanical brake for a motor vehicle. Furthermore, the invention relates to a motor vehicle which has such an electromechanical brake. State of the art The service brake is typically a brake system that uses brake fluid to press a brake piston and brake pad against a brake disc to slow the vehicle. With the increasing electrification of vehicle components, the service brake is also being developed as an electromechanical brake, thus eliminating the need for brake fluid and the associated complex valve and line system. Such an electromechanical brake could also significantly reduce maintenance requirements. In the DE 10 2010 029 856 A1 This document describes an electromechanically actuated disc brake for a motor vehicle. The brake comprises an electric motor which drives a spindle nut of a spindle drive unit via a gearbox. A spindle is axially movable via the driven spindle nut for braking. The spindle presses against a brake piston, which is guided in a brake caliper housing. A connecting piece is arranged between the spindle and the brake piston, forming a ball receptacle for a spherical end of the spindle. This connecting piece allows tilting within the housing without applying a lateral force to the spindle drive unit. The DE 19607 295 C1 This describes a brake actuator for an electric vehicle brake. The vehicle brake comprises an electric motor with a stator and a rotor connected to the spindle nut of a spindle drive assembly. The spindle is axially movable by rotating the spindle nut. A sliding bearing is arranged between the spindle and a brake piston, reducing lateral forces on the spindle assembly. The object underlying the invention is to provide an electromechanical brake which has a longer service life. The problem is solved by an electromechanical brake according to claim 1. Preferred embodiments are set forth in the dependent claims. Disclosure of the invention The invention provides an electromechanical brake for a motor vehicle. The electromechanical brake comprises an electric motor which rotates a spindle of a spindle drive unit arranged in a brake caliper housing, such that a spindle nut is displaceable in an axial direction of the brake caliper housing to apply a braking force. An elastic section is formed on the spindle, which has increased radial flexibility compared to the rest of the spindle, so that the spindle undergoes radial bending when radial forces are applied to the spindle nut. In the context of the invention, an elastic region is understood to be a locally confined area exhibiting lower bending stiffness. This elastic region is located between both axial ends of the spindle. Therefore, the elastic region is not formed at an axial end of the spindle. With lower bending stiffness, the radial bending of the elastic region is greater under the same radial force. This elastic region allows the spindle to tilt under radial forces. Due to this tilting, the spindle nut comes into lateral contact with the brake caliper housing, so that most of the radial force is transferred directly into the brake caliper housing. The radial force absorbed by the spindle drive unit is thus significantly reduced, thereby substantially minimizing wear of the spindle drive unit caused by thread tilting. This improves the durability of the spindle drive unit and, consequently, the electromechanical brake. A longer service life can therefore be achieved. In a preferred embodiment of the invention, the elastic section of the spindle has a reduced diameter compared to the rest of the spindle. This reduced diameter in the elastic section automatically decreases the bending stiffness, resulting in more elastic properties in this area. A reduced diameter offers the advantage that the spindle can still be made of the same material, with the reduced diameter occurring only in a limited area. Therefore, designing such a section is economically feasible. In a further preferred embodiment of the invention, the elastic section has a diameter that is 20-60% smaller than that of the rest of the spindle. Particularly preferably, the elastic section has a diameter that is 30-50% smaller. By such a change in diameter In comparison to the rest of the spindle, a significant change in the flexibility of the spindle is achieved, so that the spindle together with the spindle nut can be tilted via a bending in the elastic range. Preferably, a rounded area is formed in the transition zone between the reduced diameter and the diameter of the remaining spindle. This eliminates the diameter jump between the reduced diameter and the diameter of the remaining spindle. The rounded area thus reduces stresses between the different diameters, thereby improving the spindle's durability. In an advantageous embodiment, the elastic section is located adjacent to a bearing point of the spindle and on the side of the spindle facing the spindle nut. The bearing point is the location furthest from an