Electromechanical brake with lubricant reserve

Abstract

The invention relates to an electromechanical brake (10) for a motor vehicle. The invention relates to an electromechanical brake comprising an electric motor (14) which rotationally drives a spindle drive unit (42) arranged in a caliper housing (18) such that a brake actuator (54) for applying a braking force can be moved in an axial direction (52) of the caliper housing (18). A spindle (38) and / or a spindle nut (50) of the spindle drive unit (42) forms at least one cavity (58) which is connected to a thread (74) of the spindle drive unit (42) via at least one channel (70), a lubricant (62) being arranged in the cavity (58) in order to supply the thread (74) with the lubricant (62).

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, a service brake is a brake that uses brake fluid to press the brake piston and brake pads together against the brake disc to brake the vehicle. With the increasing electrification of motor vehicle systems, service brakes should also be constructed as electromechanical brakes, thus eliminating the need for brake fluid and related complex valve and piping structures. This type of electromechanical brake also significantly reduces maintenance workload.

[0003] A vehicle brake designed as a disc brake is described in document DE 10 2011 121 765 B4. This brake includes a screw drive unit comprising a screw and a screw nut, which acts on a brake piston to press the brake pads against the brake disc. The screw or screw nut has a solid object disposed in a region between the screw nut and the screw, thereby improving the lubrication of the screw drive unit. This solid object can be disposed in a notch in the screw.

[0004] Document EP 3 822 507 B1 describes an operating unit for an electric parking brake. This operating unit includes a screw drive unit having a screw and a screw nut. Clearances are provided between the root and crest of the threads of the screw nut and the screw, respectively, serving as lubricant reservoirs for the screw drive unit. Summary of the Invention

[0005] The purpose of this invention is to provide an electromechanical brake for motor vehicles that has better durability during its service life.

[0006] This objective is achieved by an electromechanical brake having the subject matter of claim 1. Preferred embodiments 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 rotatably drives a screw drive unit disposed in a brake caliper housing, thereby allowing a brake adjuster for applying braking force to move axially along the brake caliper housing. The screw and / or screw nut of the screw drive unit form at least one cavity, which is threadedly connected to the screw drive unit via at least one channel, wherein lubricant is disposed in the cavity for supplying lubricant to the threads.

[0008] In the context of this invention, the cavity refers to a space located inside the lead screw or lead screw nut. Therefore, this cavity does not directly contact the thread, but rather through at least one channel independent of the cavity itself. The cavity is formed by the removal or absence of material. Accordingly, a lighter lead screw or lead screw nut can be provided. In the case of material absence, material costs are further reduced. The cavity is connected to the thread through at least one channel. Lubricant disposed within the cavity can be provided through this channel to lubricate the lead screw drive unit. The lubricant in the cavity ensures durable lubrication in the lead screw drive unit, thereby reducing wear and extending its service life.

[0009] Although the cavity can be constructed in the lead screw nut, it is preferable to have the cavity in the lead screw. The advantage of having a cavity in the lead screw is that the centrifugal force generated by the rotation of the lead screw can better deliver the lubricant to the threads. This results in better lubrication of the threads of the lead screw drive unit.

[0010] In a preferred embodiment of the invention, a plurality of channels are arranged along the longitudinal direction of the thread. Therefore, instead of providing only one channel, multiple channels are distributed along the axial length of the thread. Accordingly, better thread lubrication is achieved throughout the entire length of the thread, thereby reducing wear.

[0011] In another preferred embodiment of the invention, the at least one channel extends radially with respect to the lead screw drive unit. While the channel may also have an axial component, a radially oriented channel allows for better lubricant delivery to the threads. Accordingly, the radially oriented channel improves thread lubrication. Furthermore, a radially oriented channel minimizes the opening in the threaded region while maintaining the maximum channel size. This thereby minimizes the negative impact of the opening on the lead screw drive unit.

[0012] Preferably, the lead screw drive unit is a ball screw drive. In the case of a ball screw drive, balls are arranged between the lead screw and the lead screw nut. This type of ball screw drive has low wear due to the balls. Accordingly, the service life of this lead screw drive unit can be improved by using a ball screw drive.

[0013] In an advantageous improvement, the at least one channel terminates between two ball raceways. A ball raceway here refers to the threaded portion that contacts the balls during the rotation of the screw. The opening of the channel is arranged such that it does not contact the balls. Accordingly, the size of the opening is designed such that it extends only between the ball raceways. This does not negatively impact the operation of the ball screw drive. This arrangement of the channel also does not reduce the load-bearing capacity of the ball screw drive.

[0014] Advantageously, the at least one cavity is arranged in the lead screw, wherein the cavity is formed by a hole. Forming the cavity by a hole provides a method for forming such a cavity. Therefore, the cavity can be formed through automated manufacturing steps. Thus, manufacturing such a cavity does not increase the manufacturing cost of the electromechanical brake.

[0015] In another advantageous embodiment, the cavity is arranged in the lead screw, wherein the cavity is closed at one axial end by a cap. By forming a cavity in the lead screw, the cavity is open at one axial end, through which lubricant can be introduced into the cavity. While this conveniently places the lubricant in the cavity, the cap prevents the lubricant from leaving the cavity through the open axial end during operation. Therefore, the cap ensures that lubricant is delivered through a channel to the threads for thread lubrication during operation.

[0016] According to an advantageous embodiment, the at least one channel is designed as a hole. The advantage of designing the channel as a hole is that such a channel can be easily and automatically formed through a drilling step. This method allows for the economical manufacture of the channel.

[0017] The present invention also proposes a motor vehicle having such an electromechanical brake. This motor vehicle achieves the advantages and characteristics described above. Attached Figure Description

[0018] Embodiments of the invention are illustrated in the accompanying drawings, and explained in more detail in the following description. The drawings show:

[0019] Figure 1 It is an electromechanical brake according to the first embodiment of the present invention;

[0020] Figure 2 It is an electromechanical brake according to the second embodiment of the present invention. Detailed Implementation

[0021] Figure 1 An electromechanical brake 10 according to a first embodiment of the present invention is shown. The electromechanical brake 10 includes an electric motor 14, which is fastened to a brake caliper housing 18. In the illustrated embodiment, the brake caliper housing 18 is connected to a brake caliper 22 that clamps a brake disc 26. A worm gear 30 extends from the electric motor 14 into the brake caliper housing 18, driving a worm wheel 34. The worm wheel 34 is arranged on a lead screw 38 of a lead screw drive unit 42, thereby allowing the lead screw drive unit 42 to be driven by the electric motor 14. The lead screw 38 is rotatably supported in the brake caliper housing 18 by a bearing 46. In the illustrated embodiment, the lead screw drive unit 42 is a ball screw drive.

[0022] By rotating the lead screw 38, the lead screw nut 50 of the lead screw drive unit 42 can move axially in the direction 52, thereby applying braking force. A brake adjuster 54, located at one axial end of the lead screw nut 50, can also move axially along with the lead screw nut 50. In this embodiment, the brake adjuster 54 is a brake pad. The lead screw 38 has a cavity 58 configured as an axial bore. Lubricant 62 can be injected into the cavity 58 through the open axial end of the lead screw 38. To prevent lubricant 62 from overflowing at this axial end, a cap 66 is used to seal the axial end.

[0023] In this embodiment, the lead screw 38 has a plurality of radial channels 70, which are distributed along the longitudinal direction of the lead screw drive unit 42. The radial channels 70 extend from the cavity 58 to the thread 74 of the ball screw drive 42. At the thread 74, the radial channels 70 terminate between two ball raceways 78. The diameter of the channels 70, configured as bores, is such that the rolling of the balls 82 is not negatively affected by the bores 70. Due to the centrifugal force generated during the rotation of the lead screw 38, lubricant 62 is guided into the thread 74 through the radial bores 70. Accordingly, adequate lubrication of the lead screw drive unit 42 is thus consistently ensured.

[0024] Figure 2 An electromechanical brake 10 according to a second embodiment of the present invention is shown. Figure 1 Unlike the illustrated embodiment, the cavity 58 is not constructed within the lead screw 38, but rather within the lead screw nut 50. This embodiment also features multiple radial channels 70 through which the thread 74 connects to the cavity 58. These channels 70 are also distributed along the longitudinal direction of the lead screw drive unit 42. Similar to the first embodiment, these channels 70 here also terminate between the ball raceways 78. This second embodiment also ensures adequate lubrication of the lead screw drive unit 42.

Claims

1. An electromechanical brake (10) for a motor vehicle, the electromechanical brake comprising an electric motor (14) that rotatably drives a screw drive unit (42) arranged in a brake caliper housing (18), thereby enabling a brake adjuster (54) for applying braking force to move along the axial direction (52) of the brake caliper housing (18). Its features are, The lead screw (38) and / or lead screw nut (50) of the lead screw drive unit (42) form at least one cavity (58), which is connected to the thread (74) of the lead screw drive unit (42) through at least one channel (70), wherein a lubricant (62) is arranged in the cavity (58) for supplying lubricant (62) to the thread (74).

2. The electromechanical brake (10) according to claim 1, characterized in that, Multiple channels (70) are arranged along the longitudinal direction of the thread (74).

3. The electromechanical brake (10) according to claim 1 or 2, characterized in that, The at least one channel (70) extends in a radial direction with respect to the lead screw drive unit (42).

4. The electromechanical brake (10) according to any one of the preceding claims, characterized in that, The lead screw transmission unit (42) is a ball screw transmission device.

5. The electromechanical brake (10) according to claim 4, characterized in that, The at least one channel (70) terminates between two ball raceways (78).

6. The electromechanical brake (10) according to any one of the preceding claims, characterized in that, The at least one cavity (58) is arranged in the lead screw (38), wherein the cavity (58) is formed by a hole.

7. The electromechanical brake (10) according to any one of the preceding claims, characterized in that, The cavity (58) is arranged in the lead screw (38), wherein the cavity (58) is closed at one axial end by a cover (66).

8. The electromechanical brake (10) according to any one of the preceding claims, characterized in that, The at least one channel (70) is a hole.

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

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