Electromechanical brake with two spindle drive units

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 an adjusting unit (38) driven by an electric motor (26) is arranged, via which a force can be applied to a brake piston (58a, 58b) so that a brake pad (20) can be applied to the brake disc (18) for braking. The adjusting unit (38) comprises at least one spindle drive unit (38a, 38b). The adjusting unit (38) comprises a first spindle drive unit (38a) and a second spindle drive unit (38b), which are jointly driven by the electric motor (26).

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 slow 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] DE 10 2018 211 443 A1 discloses a pressure generating device for a braking system of a vehicle.

[0005] US 2019 / 0003535 A1 relates to a clamp for a brake unit for overlapping the outer side of a tensioning pulley of a cabin, comprising an electric motor driving a rotating shaft, a first endless screw geared to a first primary gear, and a second endless screw geared to a second primary gear.

[0006] The object underlying the invention is to provide an electromechanical brake with which a higher braking force can be applied in a simple and economical manner.

[0007] 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

[0008] 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 an adjusting unit driven by an electric motor is arranged, via which a force can be applied to a brake piston so that a brake pad can be applied to the brake disc for braking. The adjusting unit comprises at least one spindle drive unit. The adjusting unit comprises a first spindle drive unit and a second spindle drive unit, which are jointly driven by the electric motor.

[0009] The adjustment unit effects axial adjustment of the brake piston. According to the invention, two spindle drive units are provided for the adjustment unit, each driven by a single electric motor. This makes it possible to drive both spindle drive units using just one electric motor, thus saving costs and the space required for a second electric motor. Despite this, a higher braking force can be applied to the brake disc using two spindle drive units. This makes such an electromechanical brake suitable for use in sports cars or pickup trucks. Although such an electromechanical brake has a higher braking force, it can be manufactured economically.

[0010] In a preferred embodiment of the invention, one spindle of each of the first and second spindle drive units is connected to a worm gear, which can be rotated jointly via a worm driven by the electric motor. The electric motor thus drives only a single worm, which meshes with both worm gears of the spindle drive unit. The worm is thus arranged between the two worm gears. It is thus possible to drive both spindle drive units simply and economically via a single electric motor.

[0011] In a further preferred embodiment of the invention, the worm gear of the first and second spindle drive units is each made of a plastic material. By making the worm gears of a plastic material, they can be manufactured more economically and are also lighter. Furthermore, the plastic material creates elasticity to achieve force equalization between the two spindle drive units. The worm gears are preferably made of a polyoxymethylene (POM) plastic.

[0012] Preferably, an end cap with a determined thickness is applied to the brake piston of the first spindle drive unit and the second spindle drive unit, so that a predefined axial length of the brake pistons relative to one another can be adjusted. The spindle drive unit can be closed off from the brake pad using such an end cap. This protects the spindle drive unit from dirt and moisture. In addition, the axial length of the brake piston can be adjusted using the end cap, so that any manufacturing tolerances between the two brake pistons can be compensated for, thus ensuring that the brake pad sits flat on the brake disc. This reduces the manufacturing tolerance. This accordingly lowers manufacturing costs.

[0013] In an advantageous further development, the distance between the brake disc and the brake pad is adjusted via the end caps in such a way that the distance is greater on an upstream side of the brake pad than on a downstream side. The upstream side of the brake pad is understood to be a side which, according to the usual direction of rotation of the brake disc, comes into contact with an area of ​​the brake disc first. The downstream side of the brake pad therefore only comes into contact with this area of ​​the brake disc after the upstream side. Accordingly, the spindle drive units distort in the direction of the torque applied by the brake disc. As a result, the upstream side of the brake pad is usually closer to the brake disc than the downstream side. This leads to uneven wear of the brake pad.By adjusting the end caps in advance according to this distortion, the brake pad rests evenly on the brake disc during braking, thus providing both greater braking efficiency and more even wear.

[0014] Advantageously, the first and second spindle drive units are mirrored to each other. In other words, the parts of both spindle drive units are identical, except for their mirrored configuration. This allows only one type of spindle drive unit to be constructed. Such an electromechanical brake can therefore be manufactured more economically.

[0015] In a further advantageous embodiment, the first and second spindle drive units are designed as ball screws. A ball screw has the advantage of being designed for the high loads that occur during braking. Furthermore, a ball screw has low friction, so that friction losses during rotation of the spindle drive unit can be kept to a minimum. This also makes it possible to use a smaller and therefore lighter electric motor.

[0016] The invention additionally provides a motor vehicle having such an electromechanical brake. Such a motor vehicle has the advantages and properties described above.

[0017] Embodiments of the invention are illustrated in the drawing and explained in more detail in the following description. It shows: Fig. 1 sectional view of an electromechanical brake according to an embodiment of the invention, and Fig. 2 View of the worm gears and the worm of the electromechanical brake.

[0018] In Fig. 1 shows a sectional view of an electromechanical brake 10 according to an embodiment of the invention. The electromechanical brake 10 comprises a brake caliper 14, which partially surrounds a brake disc 18. Brake pads 20 are arranged in the brake caliper 14 and can be applied to the brake disc 18 in order to brake the motor vehicle. In addition, 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 via guide pins 30 in the region of the brake caliper 14. The brake pads 20 are guided in the brake caliper holder 34.

[0019] An adjustment unit 38 consisting of a first and a second spindle drive unit 38a, 38b is arranged in the brake caliper housing 22. Both spindle drive units 38a, 38b are designed as ball screws in the illustrated embodiment. The spindle drive units 38a, 38b each have a spindle 42a, 42b, which is mounted to the brake caliper housing 22 via a bearing 46. A worm gear 50a, 50b is attached to one axial end of each spindle 42a, 42b. The worm gears 50a, 50b of the first and second spindle drive units 38a, 38b engage with a worm 54 driven by the electric motor 26.

[0020] The spindle 42a, 42b of each spindle drive unit 38a, 38b is surrounded by a rotationally fixed spindle nut 58a, 58b, which executes an axial movement upon rotation of the spindle 42a, 42b. In the embodiment shown here, the spindle nut 58a, 58b forms the brake piston of the electromechanical brake 10. At an axial end of the spindle 42a, 42b opposite the worm gear 50a, 50b, an end cap 62a, 62b is arranged on the spindle nut 58a, 58b. Via this end cap 62a, 62b, the spindle nut 58a, 58b is in contact with a pad holder 66 for the brake pad 20. The end cap 62a, 62b has an axial thickness D, via which a predefined axial length of the brake pistons 58a, 58b relative to each other can be adjusted. The two end caps 62a, 62b can thus each have a different axial thickness D. This allows any tolerance differences between the spindle drive units 38a, 38b to be compensated.It is also possible to use the end caps 62a, 62b to set a larger distance between the brake pad 20 and the brake disc 18 on a worn side of the brake pad 20 in order to achieve more even wear on the brake pad 20.

[0021] Fig. Figure 2 shows a view of the worm gears 50a, 50b and the worm 54 of the electromechanical brake 10. The figure shows that the worm gears 50a, 50b are arranged side by side, and the worm 54 is positioned between the worm gears 50a, 50b and meshes with both worm gears 50a, 50b. Thus, only a single electric motor 26 is required to drive both spindle drive units 38a, 38b. 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] DE 10 2018 211 443 A1

[0004] US 2019 / 0003535 A1

[0005]

Claims

Electromechanical brake (10) for a motor vehicle, comprising a brake caliper (14) which at least partially surrounds a brake disc (18), and a brake caliper housing (22) in which an adjusting unit (38) driven by an electric motor (26) is arranged, via which adjusting unit a force can be applied to a brake piston (58a, 58b) so that a brake pad (20) can be applied to the brake disc (18) for braking, wherein the adjusting unit (38) comprises at least one spindle drive unit (38a, 38b), characterized in that the adjusting unit (38) comprises a first spindle drive unit (38a) and a second spindle drive unit (38b), which are jointly driven via the electric motor (26). Electromechanical brake (10) according to claim 1, characterized in that a spindle (42a, 42b) of the first and the second spindle drive unit (38a, 38b) is connected to a worm wheel (50a, 50b) which are rotatable together via a worm (54) driven by the electric motor (26). Electromechanical brake (10) according to claim 2, characterized in that the worm wheel (50a, 50b) of the first and second spindle drive units (38a, 38b) is each formed from a plastic material. Electromechanical brake (10) according to one of the preceding claims, characterized in that an end cap (62a, 62b) with a determined thickness (D) is applied to the brake piston (58a, 58b) of the first spindle drive unit (38a) and the second spindle drive unit (38b), so that a predefined axial length of the brake pistons (58a, 58b) can be adjusted relative to one another. Electromechanical brake (10) according to claim 4, characterized in that a distance between the brake disc (18) and the brake pad (20) is adjusted via the end caps (62a, 62b) such that the distance on an upstream side of the brake pad (20) is greater than on a downstream side. Electromechanical brake (10) according to one of the preceding claims, characterized in that the first and second spindle drive units (38a, 38b) are mirrored to one another. Electromechanical brake (10) according to one of the preceding claims, characterized in that the first and second spindle drive units (38a, 38b) are designed as ball screw drives. Motor vehicle comprising an electromechanical brake (10) according to one of the preceding claims.

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