Electromechanical brake with bendable spindle

Abstract

The invention relates to an electromechanical brake (10) for a motor vehicle. The electromechanical brake comprises an electric motor (14) which drives in rotation a spindle (22) of a spindle transmission unit (26) arranged in a caliper housing (16) such that a spindle nut (38) can be moved in an axial direction (40) of the caliper housing (16) in order to apply a braking force (FB). According to the invention, an elastic region (46) is formed on the main shaft (22), which elastic region has a greater radial bending capacity than the rest of the main shaft (22) such that the main shaft (22) is radially bent when the main shaft nut (38) is subjected to a radial force (FR).

Description

Technical Field

[0001] This invention relates to an electromechanical brake for a motor vehicle. Furthermore, this invention also relates to a motor vehicle having such an electromechanical brake. Background Technology

[0002] Typically, service brakes use brake fluid to press the brake pistons and brake pads against the brake disc, thus braking the vehicle. With the increasing electrification of equipment in motor vehicles, service brakes are also being designed as electromechanical brakes, eliminating the need for brake fluid and the associated complex valve and piping structures. This electromechanical design also significantly reduces maintenance workload.

[0003] Document DE 10 2010 029 856 A1 describes an electromechanically operable disc brake for a motor vehicle. This brake includes an electric motor that drives a spindle nut of a spindle drive unit via a transmission mechanism. The driven spindle nut enables axial movement of the spindle for braking. The spindle presses against a guided brake piston within a brake caliper housing. A connector is arranged between the spindle and the brake piston, forming a spherical receptacle for the spherical end of the spindle. This connector allows tilting within the housing without applying lateral forces to the spindle drive unit.

[0004] Document DE 19607 295 C1 describes a brake actuator for an electric vehicle brake. The vehicle brake includes an electric motor having a stator and a rotor, the rotor being connected to a spindle nut of a spindle drive assembly. Rotation of the spindle nut causes the spindle to move axially. A sliding bearing is arranged between the spindle and the brake piston, reducing the lateral force acting on the spindle unit. Summary of the Invention

[0005] The purpose of this invention is to provide an electromechanical brake with a longer service life.

[0006] This objective is achieved by the electromechanical brake according to claim 1. Preferred designs are derived from the dependent claims.

[0007] This invention provides an electromechanical brake for a motor vehicle. The electromechanical brake includes an electric motor that drives a main shaft of a main shaft drive unit arranged in a brake caliper housing to rotate, such that a main shaft nut can move axially along the brake caliper housing to apply braking force. An elastic region is formed on the main shaft, which has a greater radial bending capacity than the rest of the main shaft, causing the main shaft to bend radially when the main shaft nut is subjected to a radial force.

[0008] In the context of this invention, the elastic region refers to a locally confined area with low bending resistance. This elastic region is located between the two axial ends of the spindle. Therefore, the elastic region is not located at the axial ends of the spindle. Due to the low bending resistance, the elastic region experiences greater radial bending under the same radial force. Thus, this elastic region allows the spindle to tilt under radial force. This tilt causes the spindle nut to make lateral contact with the brake caliper housing, allowing most of the radial force to be directly transmitted to the brake caliper housing. This significantly reduces the radial force on the spindle drive unit, thereby significantly reducing wear on the spindle drive unit caused by thread misalignment. This improves the durability of the spindle drive unit and, consequently, the durability of the electromechanical brake. Consequently, a longer service life can be achieved.

[0009] In a preferred embodiment of the invention, the elastic region of the spindle has a reduced diameter relative to the rest of the spindle. This reduced diameter in the elastic region automatically decreases its bending resistance, thereby giving the spindle greater elasticity in that region. The advantage of this reduced diameter is that the spindle can still be manufactured from the same material, with the reduced diameter only constructed in a confined area. Accordingly, constructing such a region is economically feasible.

[0010] In another preferred embodiment of the invention, the diameter of the elastic region is 20% to 60% smaller than the diameter of the rest of the spindle. More preferably, the diameter of the elastic region is 30% to 50% smaller. By changing the diameter in this way, the flexibility of the spindle is significantly altered compared to the rest of the spindle, so that the spindle and the spindle nut can be tilted by bending in the elastic region.

[0011] Preferably, a rounded region is formed in the transition area between the reduced diameter of the spindle and the diameter of the remaining portion. This eliminates abrupt diameter changes between the reduced diameter and the remaining diameter of the spindle. Consequently, the stress between the different diameters is reduced by this rounded region. Therefore, the durability of the spindle is improved by this rounded region.

[0012] In a preferred improvement, the elastic region is arranged adjacent to the support portion of the spindle and is located on the side of the spindle facing the spindle nut. The support portion is the part furthest from the axial end of the spindle nut. This distance minimizes the bending of the elastic region. Accordingly, this arrangement improves the service life of the spindle and, consequently, the service life of the electromechanical brake.

[0013] By arranging the elastic region in this way, it is no longer necessary to place it within the threaded area of ​​the spindle drive unit. Therefore, the elastic region will not negatively affect the function and operation of the spindle drive unit.

[0014] Advantageously, at least one guide element is arranged in the brake caliper housing, through which the main spindle nut is radially guided. This guide element is designed to transmit radial force from the main spindle nut to the brake caliper housing. This guide element ensures frictionless guidance of the main spindle nut even under radial loads. Advantageously, the guide element is located in the front end region of the brake caliper housing, where the distance between the main spindle nut and the brake caliper housing is minimized. This guide element prevents direct contact between the main spindle nut and the brake caliper housing in this region, thereby preventing wear on the main spindle nut.

[0015] In another advantageous embodiment, the spindle drive unit is a ball screw drive. Compared to a threaded spindle drive, a ball screw drive has the advantage of less thread friction, thereby increasing its service life. Furthermore, this ball screw drive requires a smaller electric motor.

[0016] The present invention also provides a motor vehicle having such an electromechanical brake. This motor vehicle achieves the advantages and features described above. Attached Figure Description

[0017] Embodiments of the invention are illustrated in the accompanying drawings, and these embodiments are explained in more detail in the following description. The drawings show:

[0018] Figure 1 A longitudinal sectional view of an electromechanical brake according to an embodiment of the present invention is shown. Detailed Implementation

[0019] Figure 1 The figure shows a longitudinal sectional view of an electromechanical brake 10 according to an embodiment of the present invention. The electromechanical brake 10 includes an electric motor 14 disposed on a brake caliper housing 16 of the electromechanical brake 10. The electric motor 14 drives a worm gear 18 via a worm (not shown). The worm gear 18 is disposed in the brake caliper housing 16 and mounted on the spindle 22 of a spindle drive unit 26. In the embodiment shown, the spindle drive unit 26 is a ball screw drive. The rotation of the worm gear 18 correspondingly rotates the spindle 22.

[0020] The main shaft 22 is supported in the brake caliper housing 16 by a support portion 30 configured as an angular contact ball bearing. This support is designed to withstand the axial force F of the angular contact ball bearing 30. A A retaining ring 34 is fastened within the brake caliper housing 16. By rotating the spindle 22, the spindle nut 38 of the spindle drive unit 26 can move axially in the brake caliper housing 16. The spindle nut 38 is guided here via a guide element 42 arranged in the brake caliper housing 16. A braking force F can be applied accordingly at one axial end of the spindle nut 38.B .

[0021] Adjacent to the support portion configured as an angular contact ball bearing 30, the spindle 22 has an elastic region 46 with a reduced diameter D. E The form of the structure. The diameter D of the elastic region. E This is significantly smaller than the diameter D of the rest of the main shaft 22. S The elastic region 46 allows for the application of a radial force F to the spindle nut 38. R The spindle 22 can be bent radially, thereby tilting the spindle 22 and the spindle nut 38. This achieves the ability to tilt when subjected to a radial force F. R When the spindle nut 38 presses against the brake caliper housing 16, the radial force F is borne through the brake caliper housing 16. R This reduces the load on the spindle drive unit 26, because the balls 50 of the spindle drive unit 26 need to withstand a smaller radial force F. R .

[0022] With a reduced diameter D E The elastic region 46 is in the reduced diameter D of the main shaft 22. E The diameter D of the rest of the spindle 22 S There is a rounded region 54 between them. This rounded region 54 can reduce the stress concentration effect in the area with a reduced diameter 46. Accordingly, the durability of the spindle 22 can be improved.

Claims

1. An electromechanical brake (10) for a motor vehicle, the electromechanical brake comprising an electric motor (14) that drives a spindle (22) of a spindle drive unit (26) arranged in a brake caliper housing (16) to rotate, such that a spindle nut (38) can move along the axial direction (40) of the brake caliper housing (16) to apply a braking force (F). B ); Its features are, An elastic region (46) is constructed on the spindle (22) and has a greater radial bending capacity than the rest of the spindle (22), such that when the spindle nut (38) is subjected to a radial force (F... R When the spindle (22) is bent radially.

2. The electromechanical brake (10) according to claim 1, characterized in that, The elastic region (46) of the main shaft (22) is constructed with a reduced diameter (D) relative to the rest of the main shaft (22). E ).

3. The electromechanical brake (10) according to claim 2, characterized in that, The diameter (D) of the elastic region (46) E The diameter of the spindle (22) is 20% to 60% smaller than that of the rest of the spindle.

4. The electromechanical brake (10) according to claim 2 or 3, characterized in that, The reduced diameter (D) of the main shaft (22) E ) and the diameter of the rest (D) S A rounded region (54) is formed in the transition region between ).

5. The electromechanical brake (10) according to any one of the preceding claims, characterized in that, The elastic region (46) is disposed adjacent to the support portion (30) of the main shaft (22) and is disposed on the side of the main shaft (22) facing the main shaft nut (38).

6. The electromechanical brake (10) according to any one of the preceding claims, characterized in that, At least one guide element (42) is arranged in the brake caliper housing (16), through which the spindle nut (38) is radially guided.

7. The electromechanical brake (10) according to any one of the preceding claims, characterized in that, The main shaft transmission unit (26) is a ball screw transmission device.

8. A motor vehicle, said motor vehicle comprising an electromechanical brake (10) according to any one of the preceding claims.

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