Electromechanical brake

Abstract

The invention relates to an electromechanical brake (14) for a motor vehicle. The electromechanical brake (14) comprises an electric motor (22) which, via a gear unit (26), drives a spindle drive unit (38), via which a brake actuator (46) is axially adjustable for braking. The gear unit (26) and the spindle drive unit (38) are arranged in a common brake caliper housing (10), and the spindle drive unit (38) is mounted to the brake caliper housing (10) via at least one bearing (54, 54a, 54b). The spindle drive unit (38), the gear unit (26) and the at least one bearing (54, 54a, 54b) are arranged in the brake caliper housing (10) in such a way that an inner diameter (D I ) of the brake calliper housing (10), starting from an axial side on which the brake actuator (46) is arranged, is gradually increased.

Description

[0001] The present invention relates to an electromechanical brake for a motor vehicle. Furthermore, the invention relates to 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 brake the vehicle. The parking brake, on the other hand, is designed as an electromechanical brake. With the increasing electrification of motor vehicle components, the service brake is also to be designed as an electromechanical brake, thus 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] EP 0 944 781 B1 discloses an electromechanically actuated brake which presses a brake pad against a brake disc for braking. The brake comprises a spindle drive unit having a spindle and spindle nut, the spindle being connected to the brake pad. The spindle nut is fixedly connected to a sleeve which surrounds the spindle nut on the outside. The sleeve is rotatably mounted in the brake caliper via bearings. Permanent magnets are arranged in the sleeve, forming a rotor of an electric motor. The sleeve is surrounded by a stator, via which the rotor is driven. By appropriate rotation of the spindle nut, the brake pad can be moved axially to apply a braking force.

[0005] The object underlying the invention is to provide an electromechanical brake which can be manufactured more economically.

[0006] 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

[0007] The invention specifies an electromechanical brake for a motor vehicle. The electromechanical brake comprises an electric motor that, via a gear unit, drives a spindle drive unit, via which a brake actuator is axially adjustable for braking. The gear unit and the spindle drive unit are arranged in a common brake caliper housing, and the spindle drive unit is mounted to the brake caliper housing via at least one bearing. The spindle drive unit, the gear unit, and the at least one bearing are arranged in the brake caliper housing in such a way that an inner diameter of the brake caliper housing increases gradually, starting from an axial side on which the brake actuator is arranged.

[0008] In other words, an inner diameter of the substantially cylindrical brake caliper housing increases gradually between a first and a second axial end. The spindle drive unit, the gear unit, and the at least one bearing are thus arranged in the brake caliper housing in order of size according to their outer diameter.

[0009] According to the invention, the brake caliper housing thus has no undercuts. Such undercuts are typically difficult and complex to manufacture, and thus cost-intensive. By arranging the components appropriately in the brake caliper housing, undercuts can be completely eliminated. Accordingly, such a brake caliper housing is simpler and more economical to design. According to the invention, the bearing serves not exclusively for the radial mounting of the spindle drive unit in the brake caliper housing. In particular, an axial force can also be absorbed via the at least one bearing.

[0010] In a preferred embodiment of the invention, the brake caliper housing and the brake caliper are designed as separate components. The brake caliper housing and the brake caliper therefore do not form a single component. Both components are therefore manufactured separately. Accordingly, the two components are preferably not made of the same material. The brake caliper housing can thus be made of a lighter and more cost-effective material that is not manufactured by a casting process. The brake caliper housing can thus be manufactured more economically. Such an electromechanical brake is also lighter, thus increasing driving comfort.

[0011] In a further preferred embodiment of the invention, the spindle drive unit is supported in the brake caliper housing by at least two bearings. An axial force acting on the spindle drive unit during braking is thus absorbed not by a single bearing, but by at least two bearings. Accordingly, each bearing can be designed for a lower load. The outer diameter of the bearings can thus be smaller. This also makes it possible to reduce the outer diameter of the brake caliper housing.

[0012] Preferably, the spindle drive unit is supported by a single bearing in the brake caliper housing. Unlike two bearings, the axial force is absorbed by a single bearing. Using a single bearing has the advantage over two or more bearings that the axial length of the brake caliper housing can be kept short.

[0013] In an advantageous development, at least one bearing is designed as a four-point contact bearing. The use of a four-point contact bearing has the advantage that, unlike angular contact ball bearings, it can accommodate axial loads in both directions. Furthermore, the four-point contact bearing is very space-saving. The use of a split inner ring allows a larger number of balls to be used compared to angular contact ball bearings, thus increasing the load capacity.

[0014] Advantageously, the at least one bearing is designed as an angular contact ball bearing. The use of at least one angular contact ball bearing has the advantage that a high axial load can be absorbed in one axial direction. Such a bearing is therefore advantageous in electromechanical brakes because a high axial load occurs during braking, whereas only a low axial load is present when the brake actuator is retracting. Accordingly, the angular contact ball bearing is designed such that it can absorb a higher axial load in one braking direction than when the brake actuator is retracting. Furthermore, an angular contact ball bearing enables high speeds, which are necessary for quickly adjusting the brake actuator, for example during an ABS driving maneuver. By using an angular contact ball bearing, the number of ball bearings required to absorb the axial load can be reduced.Such an electromechanical brake can therefore be manufactured more compactly, with a lower weight and more economically.

[0015] In an alternative embodiment, at least one bearing is designed as a plain bearing. The use of plain bearings has the advantage that they require significantly less space than, for example, rolling bearings. In addition, plain bearings can withstand a high axial force F A Compared to rolling bearings, plain bearings are also easier to install and are less sensitive to noise and vibration.

[0016] In a further advantageous embodiment, the gear unit is designed as a worm gear. A worm wheel of the linear gear is advantageously arranged coaxially with the spindle drive unit. By using a worm gear, the diameter of the brake caliper housing can be kept small. Likewise, an electric motor can be easily attached to the brake caliper housing. A worm gear also has the advantage of enabling a high gear ratio. Furthermore, a worm gear is low in noise and vibration, thus increasing driving comfort. Furthermore, it is possible to design the worm gear with a self-locking mechanism, allowing a parking brake for the electromechanical brake.

[0017] According to a practical embodiment, at least one disc and / or a screw-in nut is arranged in the brake caliper housing to support the bearing's axial forces. The axial forces absorbed by the bearing are thus transmitted directly into the brake caliper housing via the disc or the screw-in nut. To avoid undercuts, the disc is advantageously welded, pressed, or caulked into the brake caliper housing. The disc can thus be easily installed in the brake caliper housing.

[0018] The screw-in nut is screwed into the brake caliper housing via a thread. Therefore, only a single thread needs to be created in the brake caliper housing. This type of screw-in nut can be easily installed into the brake caliper housing. This type of screw-in nut also allows for maintenance and replacement of electromechanical brake components.

[0019] Advantageously, the disc and / or the screw-in nut are arranged on both axial sides of the bearing. This makes it possible to absorb not only the axial forces caused by braking force, but also the axial forces resulting from tensile forces. Such tensile forces can occur, for example, after a vehicle has been stationary for an extended period, when the brake pad adheres to the brake disc.

[0020] The invention also provides a motor vehicle having such an electromechanical brake. Such a motor vehicle has the advantages and properties described above.

[0021] Embodiments of the invention are illustrated in the drawing and explained in more detail in the following description. It shows: Fig. 1 sectional view through a brake caliper housing of an electromechanical brake according to a first embodiment of the invention, Fig. 2 Sectional view through a brake calliper housing of the electromechanical brake according to a second embodiment of the invention, and Fig. 3 Sectional view through a brake caliper housing of the electromechanical brake according to a third embodiment of the invention.

[0022] In Fig. Figure 1 shows a sectional view through a brake caliper housing 10 of an electromechanical brake 14 according to a first exemplary embodiment of the invention. In addition to the brake caliper housing 10, the electromechanical brake 14 comprises a separate brake caliper 18, which is fastened externally to the brake caliper housing 10. Additionally, an electric motor 22 is provided, which is arranged in the region of the brake caliper housing 10. A gear unit 26 of the electromechanical brake 14, arranged in the brake caliper housing 10, is driven by the electric motor 22. The gear unit 26 is formed from a worm 30 driven by the electric motor 22, which engages with a worm gear 34.

[0023] Additionally arranged in the brake caliper housing 10 is a spindle drive unit 38, via which a brake actuator 46 connected to a spindle nut 42 of the spindle drive unit 38 can be axially adjusted. A braking force can be applied to a brake pad (not shown here) via this brake actuator 46. One end of a spindle 50 of the spindle drive unit 38 is connected in a rotationally fixed manner to the worm gear 34 of the gear unit 26. Accordingly, the spindle 50 is rotatable via the worm gear 34. On the outside of the spindle 50 are two axially arranged bearings 54a, 54b, via which the spindle 50 is rotatably mounted relative to the brake caliper housing 10. To absorb an axial force F AThe spindle 50 forms a spindle shoulder 58, which is supported on the first bearing 54a. Between the worm gear 34 and the bearings 54a, 54b, a screw-in nut 62 is arranged in the brake caliper housing 10. The screw-in nut 62 bears directly against a second bearing 54b, so that the axial force F A is derived via the screw-in nut 62 into the brake calliper housing 10.

[0024] Fig. 1 additionally shows that the spindle drive unit 38, the bearings 54a, 54b, and the gear unit 26 are arranged according to a diameter in the brake caliper housing 10. Since the gear unit 26 with the worm gear 34 has the largest diameter, it is arranged on an axial side of the brake caliper housing 10 facing away from the brake actuator 46. An inner diameter D IThe brake caliper housing 10 thus increases gradually between the brake actuator 46 and the worm gear 34. Therefore, no undercuts need to be formed in the brake caliper housing 10, which simplifies production and reduces manufacturing costs.

[0025] Fig. Figure 2 shows a sectional view through the brake caliper housing 10 of the electromechanical brake 14 according to a second embodiment of the invention. The embodiment shown in this figure differs from that shown in Fig. 1 in that, instead of a further jump in diameter, a separate guide part 66 is inserted in the area of ​​the spindle drive unit 38, which guide part has additional functions. A guide element 70 is arranged on this guide part 66, over which the spindle nut 42 is guided. The guide part 66 additionally forms slots 74, in which anti-twist devices 78 of the spindle nut 42 are guided. A seal 82 is also provided on this guide part 66, via which seal an interior of the brake caliper housing 10 is sealed. Additional undercuts are necessary for the guide element 70 and the seal 82, so these are formed in the separate guide part 66. Accordingly, the brake caliper housing 10 can be formed essentially without undercuts.

[0026] In the shown Fig. 2, the spindle drive unit 38 is designed as a ball screw drive. The spindle 50 is also supported by a first and a second bearing 54a, 54b. In the embodiment shown here, the bearings 54a, 54b are designed as angular contact ball bearings. The second angular contact ball bearing 54b rests against a disc 86 welded into the brake caliper housing. The axial force F A can thus be diverted from the spindle 50 via the two bearings 54a, 54b into the brake caliper housing 10. Although the exemplary embodiment shown here shows two bearings designed as angular contact ball bearings 54a, 54b, other bearing combinations are also possible. For example, the forces can also be distributed asymmetrically between the two bearings 54a, 54b. The bearings 54a, 54b can be designed as an angular contact ball bearing and as an axial bearing.

[0027] On the spindle 50, above the second angular contact ball bearing 54b, a support ring 90 is arranged, which rests against the second angular contact ball bearing 54b. Tensile forces can be absorbed by the two bearings 54a, 54b via this support ring 90. Such tensile forces can occur, for example, when a brake pad sticks to a brake disc after a long period of inactivity. In this exemplary embodiment, it can also be seen that the brake caliper housing 10, starting from the brake actuator 46 up to a cover 94 of the brake caliper housing 10, has an inner diameter D I gradually increased. Accordingly, this brake caliper housing 10 can also be manufactured economically.

[0028] Fig. Figure 3 shows a sectional view through a brake caliper housing 10 of the electromechanical brake 14 according to a third embodiment of the invention. This embodiment differs from that shown in Fig.2 in that only a single bearing 54 is provided. In contrast to the previous figures, the axial force F A not distributed across two bearings 54a, 54b, but supported by a single bearing 54. Accordingly, this bearing 54 has a larger diameter than the preceding bearings 54a, 54b. Bearing 54, which in the illustrated example is also designed as an angular contact ball bearing, is arranged behind the worm gear 34, as seen from the brake actuator 46, due to its larger diameter.

[0029] In order to compensate for the distance between the spindle 50 and the angular contact ball bearing 54, an intermediate ring 98 is mounted on the spindle 50, against which the angular contact ball bearing 54 rests. Via this intermediate ring 98, the axial force F Ato the angular contact ball bearing 54. A cap 102 is arranged above the intermediate ring 98 and is connected to the intermediate ring 98. This cap 102 rests against the upper side of the angular contact ball bearing 54. A disc 86 is arranged between the cover 94 of the brake caliper housing 10 and the angular contact ball bearing 94, which is caulked to the brake caliper housing 10. The angular contact ball bearing 54 rests against the disc 86, so that the axial forces F A can be transferred into the brake caliper housing 10. To absorb tensile forces, a support ring 90 is arranged below the angular contact ball bearing 54 in the brake caliper housing. 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] EP 0 944 781 B1

[0004]

Claims

[1] Electromechanical brake (14) for a motor vehicle, comprising an electric motor (22) which drives a spindle drive unit (38) via a gear unit (26), via which a brake actuator (46) is axially adjustable for braking, wherein the gear unit (26) and the spindle drive unit (38) are arranged in a common brake calliper housing (10), and the spindle drive unit (38) is mounted to the brake calliper housing (10) via at least one bearing (54, 54a, 54b), characterized by that the spindle drive unit (38), the gear unit (26) and the at least one bearing (54, 54a, 54b) are arranged in the brake calliper housing (10) in such a way that an inner diameter (D I ) of the brake calliper housing (10), starting from an axial side on which the brake actuator (46) is arranged, is gradually increased. [2] Electromechanical brake (14) according to claim 1, characterized bythat the brake calliper housing (10) and the brake calliper (18) are designed as separate components. [3] Electromechanical brake (14) according to claim 1 or 2, characterized by that the spindle drive unit (38) is supported in the brake calliper housing (10) via at least two bearings (54a, 54b). [4] Electromechanical brake (14) according to claim 1 or 2, characterized by that the spindle drive unit (38) is supported in the brake calliper housing (10) via a single bearing (54). [5] Electromechanical brake (14) according to one of the preceding claims, characterized by that the at least one bearing (54, 54a, 54b) is designed as a four-point bearing. [6] Electromechanical brake (14) according to one of the preceding claims, characterized by that the at least one bearing (54, 54a, 54b) is designed as an angular contact ball bearing. [7] Electromechanical brake (14) according to one of the preceding claims, characterized bythat the gear unit (26) is designed as a worm gear. [8] Electromechanical brake (14) according to one of the preceding claims, characterized by that to support axial forces (F A ) of the bearing (54, 54a, 54b) at least one disc (86) and / or a screw-in nut (62) is arranged in the brake calliper housing (10), against which the bearing (54, 54a, 54b) rests. [9] Motor vehicle comprising an electromechanical brake (14) according to one of the preceding claims.

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