Electromechanical brakes and automobiles with flexible spindles

Abstract

To provide an electromechanical brake with an even longer service life. [Solution] The present invention relates to an electromechanical brake (10) for an automobile. The electromechanical brake (10) includes an electric motor (14), which rotates a spindle (22) located in a brake caliper housing (16) of a spindle drive unit (26), thereby causing the spindle nut to exert a braking force (F B The brake caliper housing (16) is displaceable in the axial direction (40) to apply a force (F). An elastic region (46) is formed in the spindle (22), which has increased radial flexibility compared to other parts of the spindle (22), thereby allowing the spindle (22) to withstand a radial force (F) at the spindle nut (38). R It undergoes radial bending under the conditions of ).

Description

[Technical Field]

[0001] This invention relates to an electromechanical brake for an automobile. In addition, this invention relates to an automobile having such an electromechanical brake. [Background technology]

[0002] Typically, service brakes are brakes in which a brake piston, along with brake pads, is pressed against a brake disc via brake fluid to slow the vehicle. As the electrification of automotive systems progresses, service brakes are also increasingly being configured as electromechanical brakes, thereby eliminating the need for brake fluid and its associated, costly valve and piping structures. Similarly, such electromechanical brakes can significantly reduce maintenance costs.

[0003] Patent Document 1 describes an electromechanically operable disc brake for an automobile. This brake includes an electric motor that drives a spindle nut of a spindle drive unit through a transmission unit. Through the driven spindle nut, the spindle is axially movable for braking. The spindle presses against a brake piston guided within a brake caliper housing. Between the spindle and the brake piston is a coupling member that forms a ball receiving portion for the ball-shaped end of the spindle. Through this coupling member, tilting within the housing is possible without applying lateral force to the spindle drive unit.

[0004] Patent Document 2 describes a brake actuator for an electric vehicle brake. This vehicle brake includes an electric motor having a stator and a rotor coupled to a spindle nut of a spindle drive mechanism. The spindle is axially movable as the spindle nut rotates. A sliding bearing is positioned between the spindle and the brake piston, thereby reducing lateral forces on the spindle unit. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] German Patent Application Publication No. 102010029856 Specification [Patent Document 2] German Patent No. 19607295 Specification [Overview of the project] [Problems that the invention aims to solve]

[0006] The fundamental problem of this invention is to provide an electromechanical brake with an even longer service life. [Means for solving the problem]

[0007] This problem is solved by an electromechanical brake having the object of claim 1. Preferred embodiments can be read from the dependent claims.

[0008] The present invention provides an electromechanical brake for an automobile. The electromechanical brake includes an electric motor which rotates a spindle located in a brake caliper housing of a spindle drive unit, thereby allowing the spindle nut to be displaced axially within the brake caliper housing to apply a braking force. An elastic region is formed in the spindle, which has increased radial flexibility compared to other parts of the spindle, thereby allowing the spindle to undergo radial bending under a radial force at the spindle nut.

[0009] In the context of this invention, the elastic region is understood to be a locally limited region having relatively low bending strength. In this case, the elastic region is located between the two axial ends of the spindle. Thus, the elastic region is not formed at the axial ends of the spindle. With this reduction in bending strength, the radial flexure of the elastic region increases under the same radial force. In this way, the elastic region allows for spindle tilting under radial force. This tilting causes the spindle nut to laterally contact the brake caliper housing, thereby directly introducing the maximum portion of the radial force into the brake caliper housing. This significantly reduces the radial force absorbed by the spindle drive unit, thereby greatly reducing wear on the spindle drive unit due to thread tilting. The durability of the spindle drive unit, and consequently the durability of the electromechanical brake, is improved. A longer service life can be achieved accordingly.

[0010] In a preferred embodiment of the present invention, the elastic region of the spindle is configured with a reduced diameter compared to the rest of the spindle. The reduced diameter in the elastic region automatically reduces the bending strength, thereby giving the spindle elastic properties in that region. The reduced diameter has the advantage that the spindle can continue to be constructed from the same material, as the reduced diameter is formed only in a limited area. Accordingly, the formation of such a region is economically feasible.

[0011] In another preferred embodiment of the present invention, the elastic region has a diameter 20 to 60% smaller than the rest of the spindle. It is particularly preferable that the elastic region has a diameter 30 to 50% smaller. Such a change in diameter results in a significant change in the flexibility of the spindle compared to the rest of the spindle, thereby allowing the spindle to tilt together with the spindle nut through flexure in the elastic region.

[0012] In the transition region between the reduced diameter and the diameter of the rest of the spindle, a chamfered region is preferably formed. That is, there is no leap in diameter between the reduced diameter section and the diameter of the rest of the spindle. Therefore, the chamfered region reduces stress between the sections with different diameters. In this way, the durability of the spindle is improved by the chamfered region.

[0013] In a preferred development, the elastic region is located adjacent to the spindle bearing location and on the spindle side facing the spindle nut. The bearing location is the furthest point from the axial end of the spindle nut. This distance minimizes the deflection of the elastic region. Accordingly, such an arrangement can extend the service life of the spindle, and consequently, the service life of the electromechanical brake.

[0014] Thus, this arrangement of the elastic region eliminates the need to place it in the thread region of the spindle drive unit. In this way, the function and operation of the spindle drive unit are not impaired by the elastic region.

[0015] Preferably, at least one guide member is positioned within the brake caliper housing to guide the spindle nut radially. This guide member is designed to introduce a radial force from the spindle nut to the brake caliper housing. Through such a guide member, frictionless guidance of the spindle nut can be ensured even when a radial load is applied. Preferably, the guide member is positioned in the front end region of the brake caliper housing. In this region, the spindle nut has the minimum distance from the brake caliper housing. The guide member prevents the spindle nut from directly contacting the brake caliper housing in this region, thereby avoiding wear on the spindle nut.

[0016] In another preferred embodiment, the spindle drive unit is a ball screw drive. The ball screw drive has the advantage of having reduced friction in the threads compared to a spindle screw drive, thereby improving the service life. Furthermore, such a ball screw drive requires only a relatively small electric motor.

[0017] The present invention additionally provides an automobile having such an electromechanical brake. Such an automobile realizes the advantages and characteristics described above.

[0018] Embodiments of the present invention are shown in the drawings and will be described in detail in the following description. The drawings show the following:

Brief Description of the Drawings

[0019] [Figure 1] It is a longitudinal sectional view showing an electromechanical brake based on an embodiment of the present invention.

Mode for Carrying Out the Invention

[0020] The drawings show a longitudinal sectional view of an electromechanical brake 10 based on an embodiment of the present invention. The electromechanical brake 10 includes an electric motor 14 disposed in a brake caliper housing 16 of the electromechanical brake 10. The electric motor 14 drives a worm wheel 18 via a worm (not shown here). The worm wheel 18 disposed in the brake caliper housing 16 is attached to a spindle 22 of a spindle drive unit 26. In the embodiment shown here, the spindle drive unit 26 is configured as a ball screw drive. When the worm wheel 18 rotates, the spindle 22 can rotate accordingly.

[0021] The spindle 22 is supported by the brake caliper housing 16 via a bearing portion 30 configured as an angular ball bearing. The axial force F of the angular ball bearing 30 ATo be able to receive it, the ring 34 is attached to the brake caliper housing 16. As the spindle 22 rotates, the spindle nut 38 of the spindle drive unit 26 can be displaced in the axial direction 40 within the brake caliper housing 16. At this time, the spindle nut 38 is guided through a guide member 42 arranged within the brake caliper housing 16. Accordingly, via the spindle nut 38, a braking force F B can be applied at the axial end of the spindle nut 38.

[0022] Adjacent to the bearing location configured as the angular ball bearing 30, the spindle 22 has an elastic region 46 configured in the form of a reduced diameter D E . At this time, the diameter D E of the elastic region is significantly smaller than the diameter D S of the other part of the spindle 22. The elastic region 46 enables the radial deflection of the spindle 22 under the radial force F R at the spindle nut 38, whereby the spindle 22 and the spindle nut 38 tilt. Thereby, under the radial force F R , the spindle nut 38 can be pressed towards the brake caliper housing 16, and as a result, the radial force F R is received by the brake caliper housing of 16. Thereby, the load on the spindle drive unit 26 is reduced. This is because only a much lower radial force F R needs to be received through the balls 50 of the spindle drive unit 26.

[0023] The elastic region 46 having a reduced diameter D E has a chamfered region 54 between the reduced diameter D E and the diameter D S of the other part of the spindle 22. Through this chamfered region 54, the notch effect in the region of the reduced diameter 46 can be reduced. Accordingly, the durability of the spindle 22 can be improved.

Description of the reference numerals

[0024] 10 Electromechanical brakes 14 Electric motor 16 Brake caliper housing 22 spindles 26 Spindle Drive Unit 38 Spindle nut 40 axis direction 42 Guide member 46 Elastic region F B Braking force F R Radial force

Claims

1. An electromechanical brake (10) for an automobile, comprising an electric motor (14), the electric motor rotationally drives a spindle (22) of a spindle drive unit (26) located in a brake caliper housing (16), thereby causing a spindle nut (38) to exert a braking force (F Ｂ In an electromechanical brake, the brake caliper housing (16) is displaceable in the axial direction (40) for the application of a force, An elastic region (46) is formed in the spindle (22), and this elastic region has increased radial flexibility compared to other parts of the spindle (22), thereby allowing the spindle (22) to withstand the radial force (F) at the spindle nut (38). Ｒ An electromechanical brake characterized by receiving radial bending under the conditions of ).

2. The elastic region (46) of the spindle (22) has a reduced diameter (D) compared to other parts of the spindle (22). Ｅ The electromechanical brake (10) according to claim 1, characterized in that it is formed by ).

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

4. The reduced diameter (D Ｅ ) and the diameter (D) of the other part of the spindle (22) Ｓ The electromechanical brake (10) according to claim 2 or 3, characterized in that a chamfered region (54) is formed in the transition region between the two.

5. The electromechanical brake (10) according to any one of claims 1 to 4, characterized in that the elastic region (46) is provided adjacent to the bearing portion (30) of the spindle (22) and on the side of the spindle (22) facing the spindle nut (38).

6. An electromechanical brake (10) according to any one of claims 1 to 5, characterized in that at least one guide member (42) is disposed in the brake caliper housing (16), and the spindle nut (38) is guided radially through the guide member.

7. The electromechanical brake (10) according to any one of claims 1 to 6, characterized in that the spindle drive unit (26) is a ball screw drive.

8. An automobile comprising an electromechanical brake (10) according to any one of claims 1 to 7.

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