Electromechanical brake with fixed caliper

Abstract

The invention relates to an electromechanical brake (10) for a motor vehicle. The electromechanical brake (10) comprises an electric motor (22) arranged on a brake caliper housing (14), wherein the electric motor (22) drives at least one adjusting mechanism (58, 82) via a gear unit (26), and the adjusting mechanism (58, 82) axially adjusts a brake actuator (62) for braking. The brake caliper housing (14) is designed as a fixed caliper, and the gear unit (26) comprises a shaft (34) via which a first and a second adjusting mechanism (58, 82), which are arranged on both axial sides of a brake disc (18), can be adjusted.

Description

[0001] The present invention relates to an electromechanical brake for a motor vehicle. Furthermore, the invention relates to a motor vehicle comprising 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 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.

[0004] The object underlying the invention is to provide an electromechanical brake for a motor vehicle which has a fixed caliper and can be produced compactly 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 an electric motor arranged on a brake caliper housing. The electric motor drives at least one adjustment mechanism via a gear unit, and the adjustment mechanism axially adjusts a brake actuator for braking. The brake caliper housing is designed as a fixed caliper, and the gear unit comprises a shaft via which a first and a second adjustment mechanism, which are arranged on both axial sides of a brake disc, can be adjusted.

[0007] The adjustment mechanism is a structural unit that converts the rotary motion of the electric motor and the gear unit into a translatory motion. The brake actuator is not part of the adjustment mechanism, but the brake actuator interacts with it. Accordingly, the brake actuator is adjusted for braking by the adjustment mechanism. Unlike a floating caliper, a fixed caliper has no moving housing parts. Accordingly, actuation of the brake disc must be provided on both sides of the fixed caliper.

[0008] According to the invention, only a single electric motor is required to drive the two adjustment mechanisms on both sides of the brake disc. This eliminates the need for a separate electric motor for each side. Accordingly, the space required for such an electromechanical brake can be kept to a minimum. Likewise, only a single control unit is required for the electric motor. This also reduces costs for the electromechanical brake. Such an electromechanical brake can be manufactured compactly and economically. Furthermore, an adjustment mechanism on both sides of the brake disc can achieve greater braking performance compared to a floating caliper.

[0009] In a preferred embodiment of the invention, the shaft is a drive shaft of the electric motor. This eliminates the need for additional components between the electric motor and the shaft to drive the shaft. This allows for a corresponding reduction in space and weight.

[0010] In a further preferred embodiment of the invention, the brake caliper housing has an opening on top through which brake pads can be replaced. Changing the brake pads is simplified via the opening in the brake caliper housing. Likewise, an inspection of the electromechanical brake, such as checking the brake pad thickness, can be easily performed via the opening.

[0011] Preferably, at least one adjustment mechanism comprises at least one spindle drive unit. Although one spindle drive unit is preferably provided per adjustment mechanism, it is alternatively also possible to use two or more spindle drive units per adjustment mechanism. By using more spindle drive units, it is possible to apply braking force at multiple points on the brake pad. This also allows the brake pad to be designed larger.

[0012] A spindle drive unit has the advantage of enabling high power transmission with low weight and low friction. This makes it possible to create a lightweight electromechanical brake.

[0013] In an advantageous refinement, the spindle drive unit is designed as a ball screw drive. In a ball screw drive, balls are arranged in the threads between the spindle nut and the spindle. These balls further reduce friction, allowing the use of a smaller electric motor that requires less installation space.

[0014] Advantageously, at least one adjustment mechanism comprises at least one cam mechanism. A cam mechanism or a ramp mechanism converts a rotational movement into a translational movement for the brake actuator. Various cam mechanisms are known. Ball ramp mechanisms are known with two coaxially arranged discs, between which, for static determinacy, three balls are usually arranged distributed in the circumferential direction. More than three balls can also be provided. One of the two discs can be driven in rotation. On or within mutually facing end surfaces, the discs have ramps or curves running in the circumferential direction, which rise in a circumferential direction and in which balls roll. The ramps are usually groove-shaped depressions that become lower in a circumferential direction.

[0015] When one disc is rotated, the balls roll in the increasing direction of the ramps and push the discs apart, creating the translational movement. When the direction of rotation is reversed, the two discs move closer together. Instead of balls, other rolling elements can be used, such as cylindrical or tapered rollers. These can be rotatably mounted on one disc, so that only the other disc has ramps on which the rollers or other rolling elements roll. A ramp mechanism without rolling elements is also conceivable, having one or more ramps running in the circumferential direction that push off a counter-body when rotated, thereby creating a translational movement like in the well-known ball ramp mechanism. A ramp mechanism, when it has rolling elements, has the advantage of low friction.

[0016] In a further advantageous embodiment, the transmission unit comprises a planetary gear, a spur gear, and / or a belt drive. A planetary gear has the advantage of ensuring low-lateral-force output with a high gear ratio. Furthermore, a planetary gear can transmit high torque, and the planetary gear can be used in an axial configuration to save space. A spur gear, on the other hand, has a small number of components and can therefore be designed simply, economically, and with minimal weight.

[0017] With a belt drive, which can also be a toothed belt, large gear ratios can be achieved. Unlike other transmissions, a belt drive can bridge larger distances. Furthermore, a belt drive is simple and inexpensive to construct, and also quiet.

[0018] According to a practical embodiment, a control unit for controlling the electric motor is attached to an axial side of the electric motor facing away from the brake caliper housing. The brake caliper housing and the control unit are thus arranged on two axially different sides of the electric motor relative to a rotor of the electric motor. This places the control unit at the greatest possible distance from the brake disc. The control unit and thus the electrical components are accordingly protected from heat development by the brake disc. This position also offers favorable installation conditions for the control unit.

[0019] Alternatively, a control unit for controlling the electric motor is located near a shaft end on the brake caliper housing. In this position, the control unit is close to the shaft end, allowing the shaft speed to be easily determined using a speed sensor. Accordingly, the speed sensor can be housed in a housing of the control unit, protecting it from external influences.

[0020] Preferably, the control unit includes a speed sensor that can measure the shaft's speed. By accommodating the speed sensor in a housing of the control unit, the speed sensor can be protected from external influences. Furthermore, the wiring between the speed sensor and a rail of the control unit is reduced.

[0021] The invention additionally provides a motor vehicle having such an electromechanical brake. Such a motor vehicle has the advantages and properties described above.

[0022] 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, Fig. 2 embodiment of a part of the gear unit, and Fig. 3 Sectional view of an electromechanical brake according to another embodiment of the invention.

[0023] In Fig. Figure 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 housing 14, which is designed as a fixed caliper. The brake caliper housing 14 surrounds a brake disc 18 of a motor vehicle on both sides. The electromechanical brake 10 additionally comprises an electric motor 22, which is arranged on the brake caliper housing 14. The electric motor 22 drives a transmission unit 26, which has a first and a second transmission part 26a, 26b. Both transmission parts 26a, 26b are arranged on different axial sides of the brake disc 18.

[0024] The gear unit 26 has a common shaft 34 for both gear parts 26a, 26b, which is a drive shaft of the electric motor 22. In the exemplary embodiment shown, the shaft 34 is arranged above the brake disc 18 and extends from the electric motor 22 to an opposite inner side of the brake caliper housing 14. At a shaft end 38 and in the area of ​​the electric motor 22, the shaft 38 is mounted to the brake caliper housing 14 via a bearing 42. The first gear part 26a comprises a first spur gear 46 arranged on the shaft 34, which engages with another spur gear 50. The spur gear transmission 54 thus formed forms a transmission ratio to a first adjustment mechanism 58. A brake actuator 62 is axially displaceable via the first adjustment mechanism 58, which can be designed, for example, as a spindle drive unit.In the embodiment shown here, the brake actuator 62 comprises a brake pad 62a, which can be applied to the brake disc 18.

[0025] On a side of the brake disc 18 facing away from the first spur gear 46, a second spur gear 66 of the second gear part 26b is arranged on the shaft 34. This spur gear 66 drives a planetary gear 70 of the second gear part 26b. Although the gear parts 26a and 26b are designed differently in the illustrated embodiment, they can also be designed identically.

[0026] A top view of the planetary gear 70 is shown in Fig. 2. The second spur gear 66 meshes with a ring gear 74 of the planetary gear 70. A sun gear 78 of the planetary gear 70 can, for example, be formed from one end of a spindle of the spindle drive unit. It is also possible for the sun gear 78 to drive a cam disk of a second adjustment mechanism 82 designed as a cam disk mechanism. In both cases, the rotary motion is converted into a translatory motion. In the same way as with the first adjustment mechanism 58, a brake actuator 62 comprising a brake pad 62a can be applied to the brake disk 18.

[0027] The electromechanical brake 10 additionally comprises a control unit 86, which is arranged on the electric motor 22 at an axial end opposite the brake caliper housing 14. The electric motor 22 can be controlled via the control unit 86. Additionally, a speed sensor 90 is arranged in the control unit 86, via which a speed of the electric motor 22 can be measured. An opening 94 is formed in the brake caliper housing 14 above the brake pads 62a, through which the brake pads 62a can be replaced.

[0028] Fig. Figure 3 shows a sectional view of the electromechanical brake 10 according to a further embodiment of the invention. This embodiment differs from the one shown in Fig.1 in that the control unit 86 is not arranged on the electric motor 22. The control unit 86 in this exemplary embodiment is mounted in the region of the shaft end 38 on the brake caliper housing 14. The speed of the electric motor 22 can be determined via the shaft end 38 using the corresponding speed sensor 90 in the control unit 86, also at this position. 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 0 944 781 B1

[0003]

Claims

[1] Electromechanical brake (10) for a motor vehicle, comprising an electric motor (22) which is arranged on a brake calliper housing (14), wherein the electric motor (22) drives at least one adjusting mechanism (58, 82) via a gear unit (26), and the adjusting mechanism (58, 82) axially adjusts a brake actuator (62) for braking, characterized by in that the brake calliper housing (14) is designed as a fixed calliper and the gear unit (26) comprises a shaft (34) via which a first and a second adjusting mechanism (58, 82), which are arranged on both axial sides of a brake disc (18), can be adjusted. [2] Electromechanical brake (10) according to claim 1, characterized by that the shaft (34) is a drive shaft of the electric motor (22). [3] Electromechanical brake (10) according to claim 1 or 2, characterized by that the brake calliper housing (14) has an upper opening (94) through which brake pads (62a) can be replaced. [4] Electromechanical brake (10) according to one of the preceding claims, characterized by that at least one adjusting mechanism (58, 82) comprises at least one spindle drive unit. [5] Electromechanical brake (10) according to claim 4, characterized by that the spindle drive unit is designed as a ball screw drive. [6] Electromechanical brake (10) according to one of the preceding claims, characterized by that at least one adjusting mechanism (58, 82) comprises at least one cam mechanism. [7] Electromechanical brake (10) according to one of the preceding claims, characterized by that the gear unit (26) comprises a planetary gear (70), a spur gear (54) and / or a belt gear. [8] Electromechanical brake (10) according to one of the preceding claims, characterized bythat a control device (86) for controlling the electric motor (22) is fastened to an axial side of the electric motor (22) facing away from the brake calliper housing (40). [9] Electromechanical brake (10) according to one of claims 1 to 7, characterized by that a control device (86) for controlling the electric motor (22) is arranged in the region of a shaft end (38) on the brake calliper housing (14). [10] Electromechanical brake (10) according to one of claims 8 or 9, characterized by that the control unit (86) has a speed sensor (90) via which a speed of the shaft (34) can be measured. [11] Motor vehicle comprising an electromechanical brake (10) according to one of the preceding claims.

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