Electromechanical brake

Abstract

The invention relates to an electromechanical brake (10) for a motor vehicle. The electromechanical brake (10) comprises a brake caliper (14) which at least partially surrounds a brake disc (18) and a brake caliper housing (22) in which a gearbox (54) driven by an electric motor (26) is arranged. The gearbox (54) comprises at least one worm gear (50) which engages with a worm (62) driven by the electric motor (26). The worm gear (50) is attached via a thread (94, 70) to an axle (82) of a threaded drive unit (58), and means (102) are provided to block relative rotation of the worm gear (50) with respect to the axle (82) of the threaded drive unit (58).

Description

[0001] The present invention relates to an electromechanical brake for a motor vehicle and a motor vehicle having such an electromechanical brake. State of the art

[0002] Typically, the service brake is a brake in which a brake piston, together with a brake pad, is pressed onto a brake disc via brake fluid to slow the vehicle. With the increasing electrification of automotive components, the service brake is also being designed as an electromechanical brake, eliminating the need for brake fluid and the associated complex valve and line assembly. Such an electromechanical brake could also significantly reduce maintenance requirements.

[0003] EP 1 030 979 B1 discloses an electromechanical braking device for braking a motor vehicle wheel. The braking device comprises a brake caliper in which an electric motor is arranged. The electric motor drives a spindle drive unit, via which brake pads arranged on a brake caliper of the brake caliper can be applied to a brake disc for braking.

[0004] The object underlying the invention is to provide an electromechanical brake for a motor vehicle which can be manufactured simply and economically.

[0005] The object is achieved by an electromechanical brake having the subject matter of patent claim 1. Preferred embodiments can be found in the dependent claims. Disclosure of the invention

[0006] The invention specifies an electromechanical brake for a motor vehicle. The electromechanical brake comprises a brake caliper that at least partially surrounds a brake disc, and a brake caliper housing in which a gear mechanism driven by an electric motor is arranged. The gear mechanism comprises at least one worm gear that engages with a worm gear driven by the electric motor. The worm gear is attached to an axle of a screw drive unit via a thread, and means are provided to block rotation of the worm gear relative to the axle of the screw drive unit.

[0007] Using a thread between the axis of the screw drive unit and the worm gear, the worm gear can be easily and economically mounted on the axis of the screw drive unit. Unlike with other assembly methods, no force needs to be applied to the worm gear or the axis. The force-free mounting of the worm gear on the axis of the screw drive unit prevents the teeth of the worm gear or worm from being accidentally damaged during assembly. The resulting scrap of parts can be reduced accordingly. This means that such an electromechanical brake can be manufactured more economically. This means that after assembly, the worm gear cannot accidentally become detached from the axis of the screw drive unit. Despite a thread between the worm gear and the screw drive unit, a permanently strong connection can be created.

[0008] In a preferred embodiment of the invention, the thread direction is designed such that, upon application of a braking force, the worm gear and the axle can be screwed together. In other words, the worm gear and the axle are screwed together upon application of a braking force. This prevents the worm gear and the axle from separating when a braking force is applied.

[0009] Preferably, the means is a screw that rests against the worm gear at one axial end and is screwed to the axle. The screw prevents the worm gear from rotating away from the axle in a direction of loosening. Although the axle can also be welded or caulked to the worm gear instead of a screw, the screw provides a simple means by which relative rotation of the worm gear and the axle can be prevented.

[0010] In an advantageous development, a screw thread direction is opposite to a thread direction of the worm gear. In other words, the thread directions of the screw thread and the thread of the worm gear are opposite. This prevents the screw from also being loosened when the worm gear is loosened. By designing the thread directions in this way, the screw is tightened in a loosening direction of the worm gear. This permanently prevents the worm gear from accidentally becoming detached from the axle.

[0011] Advantageously, the worm gear and the spindle of the screw drive unit form at least one clearance fit, which aligns the worm gear with the spindle. During assembly, when the worm gear is screwed onto the spindle, the clearance fit is created. This aligns the worm gear with the spindle of the screw drive unit. The clearance fit thus enables precise alignment of the worm gear.

[0012] In a further advantageous embodiment, the worm gear and the spindle of the screw drive unit each form a clearance fit at the axial ends of the worm gear. By forming two clearance fits, the worm gear is prevented from tilting, unlike with a single clearance fit. This ensures that the worm gear maintains its aligned position. Furthermore, by forming the clearance fits at the axial ends of the worm gear, the tilting stiffness is increased.

[0013] According to a practical design, the screw drive unit is a ball screw. A ball screw has the advantage of being designed to withstand the high loads encountered during braking. Furthermore, a ball screw has low friction, so friction losses during rotation of the screw drive unit can be kept to a minimum. This also makes it possible to use a smaller and therefore lighter electric motor.

[0014] According to a further expedient embodiment, the brake caliper housing is designed such that the worm gear and the screw drive unit can be mounted from opposite sides of the brake caliper housing. Typically, the worm gear is larger than the screw drive unit. By mounting them on opposite sides of the brake caliper housing, the brake caliper housing can be adapted to the size of the screw drive unit, so that the screw drive unit is held by the brake caliper housing. The number of components for holding the screw drive unit in the brake caliper housing can thereby be reduced. However, the screw drive unit and the worm gear can only be connected to one another in the housing. By using a thread between the screw drive unit and the worm gear, such a connection between the two components within the brake caliper housing can be established easily and without force.

[0015] The invention additionally provides a motor vehicle having such an electromechanical brake. Such a motor vehicle has the advantages and properties described above.

[0016] Embodiments of the invention are illustrated in the drawing and explained in more detail in the following description. It shows: Fig. 1 Perspective view of an electromechanical brake according to an embodiment of the invention, Fig. 2 Sectional view through the brake calliper housing before mounting the worm gear, and Fig. 3 Sectional view through the brake caliper housing after installation of the worm gear.

[0017] In Fig. Figure 1 shows a perspective view of an electromechanical brake 10 according to an embodiment of the invention. The electromechanical brake 10 comprises a brake caliper 14, which engages a brake disc 18. Brake pads (not shown) are arranged in the brake caliper 14 and can be applied to the brake disc 18 to brake the motor vehicle. Additionally, the electromechanical brake 10 comprises a brake caliper housing 22. An electric motor 26 of the electromechanical brake 10 is attached to the brake caliper housing 22. The electromechanical brake 10 is connected to a brake caliper holder 34 in the region of the brake caliper 14 via guide pins 30.

[0018] A cover 38 is arranged on the brake caliper housing 22, by means of which the housing can be closed. The cover 38 is held by three retaining elements 42. In the exemplary embodiment shown here, the retaining elements 42 are designed as screws that are screwed into the brake caliper housing 22 and simultaneously have a retaining piece 42a that rests against the cover 38. The cover 38 has a passage 46 at one point, through which cables (not shown) can be inserted into the brake caliper housing 22.

[0019] Fig. 2 shows a sectional view through the brake caliper housing 22 prior to assembly of a worm gear 50 of the electromechanical brake 10. The worm gear 50 is designed as part of a gear 54 of the electromechanical brake 10. The gear 54 additionally comprises a screw drive unit 58, which in the exemplary embodiment shown here is designed as a ball screw drive. A worm 62 driven by the electric motor 26 is also arranged in the brake caliper housing 22 and is in engagement with the worm gear 50 when it is assembled. In the figure shown, however, the worm gear 50 is positioned above the worm 62. The worm gear 50 forms a hub 66, on which an internal hub thread 70 is provided.

[0020] The screw drive unit 58 comprises a spindle nut 74 and a spindle 78, which is arranged rotatably relative to the spindle nut 74. The screw drive unit 58 forms an axle 82, which in this case is formed by the spindle 78. The spindle 78 is rotatably mounted relative to the brake caliper housing 22 via a bearing 86. A threaded bore 90 is provided at an axial end of the axle 82 facing the worm gear 50. In addition, an external thread 94 is formed in the region of an axial end of the axle 82. This external thread 94 is screwed to the internal hub thread 70 of the worm gear 50 in an assembled state.

[0021] In Fig.Figure 3 shows a sectional view through the brake caliper housing 22 after the worm gear 50 has been installed. In this figure, the worm gear 50 and the axle 82 are screwed together via the threads 70, 94. The thread direction is designed such that they are screwed together in a direction of rotation of the worm gear 50 in which the screw drive unit 58 applies a braking force. This prevents the connection between the worm gear 50 and the axle 82 of the screw drive unit 58 from becoming loose.

[0022] This figure also shows a means 102 by which relative rotation between the worm gear 50 and the axis 82 of the screw drive unit 58 is blocked. In the exemplary embodiment shown here, this means 102 is designed as a screw, which rests against an axial end of the worm gear 50 via an intermediate washer 106. The screw 102 is fastened to the threaded bore 90 of the axis 82. The screw thread direction and the thread direction of the axis 82 are opposite. This prevents the worm gear 50 from becoming loose from the axis 82 over time.

[0023] In the embodiment shown, the worm wheel 50 and the axis 82 each form a clearance fit 110 at the axial ends of the worm wheel 50, via which the worm wheel 50 is aligned with the axis 82 of the screw drive unit 58. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 1 030 979 B1

[0003]

Claims

[1] Electromechanical brake (10) for a motor vehicle, comprising a brake calliper (14) which at least partially surrounds a brake disc (18) and a brake calliper housing (22) in which a gear (54) driven by an electric motor (26) is arranged, wherein the gear (54) comprises at least one worm wheel (50) which is in engagement with a worm (62) driven by the electric motor (26), characterized by that the worm wheel (50) is fastened via a thread (94, 70) on an axis (82) of a screw drive unit (58) and means (102) are provided to block a relative rotation of the worm wheel (50) to the axis (82) of the screw drive unit (58). [2] Electromechanical brake (10) according to claim 1, characterized by that a thread direction of the thread (94, 70) is designed such that the worm wheel (50) and the axle (82) can be screwed together when a braking force is applied. [3] Electromechanical brake (10) according to claim 1 or 2, characterized by that the means (102) is a screw which bears against the worm wheel (50) at one axial end and is screwed to the axle (82). [4] Electromechanical brake (10) according to claim 3, characterized by that a screw thread direction is opposite to a thread direction of the worm wheel (50). [5] Electromechanical brake (10) according to one of the preceding claims, characterized by that the worm wheel (50) together with the axis (82) of the screw drive unit (58) form at least one clearance fit (110) via which the worm wheel (50) is aligned with the axis (82). [6] Electromechanical brake (10) according to one of the preceding claims, characterized by that the worm wheel (50) and the axis (82) of the screw drive unit (58) at axial ends of the worm wheel (50) together form a clearance fit (110). [7] Electromechanical brake (10) according to one of the preceding claims, characterized by that the screw drive unit (58) is a ball screw drive. [8] Electromechanical brake (10) according to one of the preceding claims, characterized by that the brake calliper housing (22) is designed such that the worm gear (50) and the screw drive unit (58) can be mounted from opposite sides of the brake calliper housing (22). [9] Motor vehicle comprising an electromechanical brake (10) according to one of the preceding claims.

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