Electromechanical vehicle brake

Abstract

Title: Electromechanical Vehicle Brake An electromechanical vehicle brake (10) comprising an electric motor (14) mounted on a brake caliper housing (18), a transmission unit (30) coupled to a spindle (34) of a spindle drive unit (38) is driven by the electric motor (14) so ​​that the brake actuator (42) is axially displaced to generate the braking force. A spindle nut (50) of the spindle drive unit (38) and the spindle (34) are mounted for rotation relative to each other by a first ball screw mechanism (66); a second ball screw mechanism (74) is provided between the spindle nut (50) and the brake caliper housing (18); the spindle nut (50) is mounted for rotation by this ball screw mechanism relative to the brake caliper housing (18). Figure 1

Description

Title of the invention: Electromechanical vehicle brake. FIELD OF THE INVENTION

[0001] The present invention relates to an electromechanical motor vehicle brake comprising an electric motor mounted on a brake caliper housing, a transmission unit coupled to a spindle of a spindle drive unit is driven by the electric motor to axially move the brake adjusting member to generate the brake force. STATE OF THE ART

[0002] Typically, the service brake is a brake in which brake fluid pushes a brake piston and its lining against the brake disc to slow the vehicle. In contrast, the parking brake is an electromechanical brake. Due to the increasing electrification of vehicle equipment, the service brake must also be designed as an electromechanical brake to avoid brake fluid and the corresponding complex structures of valves and lines. Such an electromechanical brake significantly reduces maintenance.

[0003] Document EP 0 944 781 B1 describes an electromechanically operated brake for braking by pressing its brake lining against the brake disc. The brake comprises a spindle drive unit with a spindle and its nut; the spindle is connected to the brake lining. The spindle nut is integral with the sleeve surrounding it. The sleeve is rotatably mounted by a bearing in the brake caliper. The sleeve incorporates permanent magnets forming the rotor of an electric motor. The sleeve is surrounded by a stator to drive the rotor. Rotation of the spindle nut axially displaces the brake lining to exert a braking force.

[0004] Document EP 3 421 773 B1 describes a telescopic roller spindle actuator for aviation.

[0005] Document EP 0 448 711 B1 describes a ball screw spindle adjustment device.

[0006] Document WO 2022 / 210677 Al describes a ball circulation spindle.

[0007] PURPOSE OF THE INVENTION

[0008] The present invention aims to develop an electromechanical vehicle brake capable of applying a significant braking force and which, nevertheless, is compact and economical to manufacture.

[0009] DESCRIPTION AND ADVANTAGES OF THE INVENTION

[0010] To this end, the invention relates to an electromechanical vehicle brake. This electromechanical brake comprises an electric motor mounted in a caliper housing of brake and a transmission unit coupled to a spindle of a spindle drive unit driven by the electric motor to axially move the brake actuator to generate the braking force.

[0011] This brake is characterized by a spindle nut of the spindle drive unit and the spindle are mounted to rotate relative to each other by a first ball screw mechanism, a second ball screw mechanism being provided between the spindle nut and the brake caliper housing, the spindle nut being mounted to rotate by this ball screw mechanism relative to the brake caliper housing.

[0012] A brake actuator is a component that axially drives the spindle nut to apply a force to the brake lining or brake disc. A ball screw mechanism is formed by a set of balls that move in ball tracks made in two parts installed opposite each other. According to the invention, the spindle nut does not cooperate with the brake caliper housing by means of a rotational lock, but is connected via a second ball screw mechanism, which rotates relative to the brake caliper housing. This eliminates the need for a rotational lock on the spindle nut.

[0013] The two ball screw mechanisms allow the braking force to be received by a greater number of balls. This, conversely, makes it possible to apply a higher braking force to the electromechanical brake without increasing the axial length of the spindle drive unit to accommodate a larger number of balls. This allows for a more compact electromechanical brake despite the greater braking force. To maintain the higher braking force, it is possible, alternatively, to use larger balls, which reduces the gear ratio relative to the motor. Correspondingly, this would require a much larger electric motor, which would increase the cost of such an electromechanical brake. The device according to the invention, consisting of two ball screw mechanisms, leaves the gear ratio unchanged, so the cost of the electric motor remains the same.The invention thus allows for a more economical manufacture of the electromechanical brake, even though the braking force it provides is greater.

[0014] According to a preferred embodiment of the invention, the spindle nut acts on the brake actuator via a rotationally decoupled bearing. The two ball screw mechanisms rotate not only the spindle but also the spindle nut. The spindle nut, however, is part of the spindle transmission unit that transmits the braking force to the brake actuator. This arrangement of a corresponding bearing that decouples the rotational movement of the spindle nut prevents decoupling between the brake actuator and the brake lining. The brake lining is thus integral with the brake actuator.

[0015] According to another preferred development of the invention, the bearing is a plain bearing. A plain bearing has the advantage of being economical to manufacture. Furthermore, such a plain bearing is compact, allowing for the creation of small electromechanical brakes. In addition, the plain bearing requires minimal maintenance; it is easy to install and relatively insensitive to vibration and noise. Thus, the plain bearing improves user comfort.

[0016] Preferably, the bearing is a needle bearing, advantageously a low-profile axial needle bearing. Furthermore, a needle bearing allows for the transmission of greater forces. A needle bearing also has lower friction torque at low rotational speeds. Compared to plain bearings, the needle bearing experiences less wear.

[0017] According to an advantageous development, the spindle transmission unit acts on a hydraulic piston to generate the brake pressure for the brake actuator. The braking force can thus be transmitted via the brake hydraulic fluid. Consequently, the brake actuator does not act directly on the brake lining. The hydraulic transmission of the brake force provides an alternative to a purely mechanical transmission of force.

[0018] Advantageously, the balls of the second ball mechanism are larger than the balls of the first ball screw mechanism. Larger balls have the advantage of resisting a higher force due to their larger bearing surface compared to smaller balls. The large balls of the second ball screw mechanism allow a reaction force opposing the braking force to be introduced directly into the yoke housing. The spindle transmission unit can thus be designed for lower loads, making it more compact.

[0019] According to another development, the first ball screw mechanism has a ball return in the spindle. By means of this ball return, the balls are transported through a return channel to the axially opposite end of the ball screw mechanism. This allows for a greater actuation stroke. Implementing the return in the spindle does not result in any additional space, so this ball return is compact.

[0020] The invention also applies to a vehicle equipped with such an electromechanical brake. This vehicle has the advantages and properties described above. Brief description of the drawings

[0021] The present invention will be described in more detail below with reference to embodiments of electromechanical brakes according to the invention shown in the accompanying drawings, in which:

[0022] [Fig. 1] Perspective view of an example of an embodiment of an electromechanical brake,

[0023] [Fig. 2] Cross-sectional view of an example of an embodiment of a drive unit brooch according to the invention

[0024] [Fig.3] Cross-sectional view of another example of an embodiment of a drive unit spindle according to the invention.

[0025] DESCRIPTION OF EMBODIMENT METHODS OF THE INVENTION

[0026] Figure 1 is a perspective view of an electromechanical brake 10 according to an embodiment of the invention. The electromechanical brake 10 comprises an electric motor 14 housed in a brake caliper housing 18. The electric motor 14 drives the transmission unit 30 formed by a screw 22 and a worm gear 26. The worm gear 26 drives a spindle 34 of a spindle drive unit 38 (not shown in this figure), so as to move the brake actuator 42 (see Figure 2), which includes a push plate 46 in this embodiment, axially to apply the brakes.

[0027] Figure 2 is a cross-sectional view of the spindle drive unit 38 according to one embodiment of the invention. The spindle drive unit 38 comprises the spindle 34 driven by the worm gear 26 and an axially adjustable nut 50. In the embodiment shown, the nut 50 acts via a bearing 54 on the brake actuator 42. The brake actuator 42 here comprises the push plate 46 equipped with a brake lining 58. The bearing 54 in this embodiment is not detailed because it could be a plain bearing or a needle bearing.

[0028] A first ball screw mechanism 66, formed by a large number of balls 62, is provided between the spindle 34 and the nut 50; the spindle 34 and the nut 50 are mounted to rotate relative to each other by this mechanism. In addition, a second ball screw mechanism 74, having a large number of balls 70, is provided between the spindle nut 50 and the brake caliper housing 18; the nut 50 is mounted to rotate relative to the brake caliper housing 18 by this ball screw mechanism. The two ball screw mechanisms 66, 74 amplify the braking force received, without having to lengthen the spindle drive unit 38. In the embodiment shown, the balls 70 of the second ball screw mechanism 74 are larger than the screws 62 of the first ball screw mechanism 66. Thus, the braking force that the brake caliper housing 18 must receive is increased, which makes the spindle transmission unit 38 more compact.

[0029] Figure 3 is a cross-sectional view of a spindle drive unit 38 of another embodiment of the invention. This embodiment differs from the spindle drive unit 38 shown in Figure 2 by a return of balls 78 in the spindle 34 which guides the balls 62 to the axial end opposite to that of the first ball screw mechanism 66.

[0030] NOMENCLATURE OF MAIN ELEMENTS

[0031] 10 Electromechanical brake

[0032]

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[0040]

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[0044]

[0045]

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[0047]

[0048] 14 Electric motor 18 Brake caliper housing 20 Screw 26 Screw wheel 30 Transmission unit 34 Spindle 38 Spindle drive unit 42 Brake actuator 46 Pressure plate 50 Nut 54 Bearing 58 Brake lining 62 Ball of first ball screw mechanism 66 First ball screw mechanism 70 Ball of second ball screw mechanism 74 Second ball screw mechanism 78 Ball return

Claims

Demands

1. Electromechanical motor vehicle brake (10) comprising an electric motor (14) mounted in a brake caliper housing (18), a transmission unit (30) coupled to a spindle (34) of a spindle drive unit (38) is driven by the electric motor (14) to axially move the brake actuator (42) to generate the braking force, brake characterized in that a spindle nut (50) of the spindle drive unit (38) and the spindle (34) are mounted to rotate relative to each other by a first ball screw mechanism (66), a second ball screw mechanism (74) being provided between the spindle nut (50) and the brake caliper housing (18), the spindle nut (50) being mounted to rotate by this ball screw mechanism relative to the brake caliper housing (18).

2. Electromechanical brake (10) according to claim 1, characterized in that the spindle nut (50) acts on the brake actuator (42) by means of a bearing (54) decoupled from the rotational movement.

3. Electromechanical brake (10) according to claim 2, characterized in that the bearing (54) is a plain bearing.

4. Electromechanical brake (10) according to claim 2, characterized in that the bearing (54) is a needle bearing.

5. Electromechanical brake (10) according to any one of the preceding claims, characterized in that the spindle drive unit (38) acts on a hydraulic piston to generate the brake force applied to the brake actuator (42).

6. Electromechanical brake (10) according to any one of the preceding claims, characterized in that the balls (70) of the second ball screw mechanism (74) are larger than the balls (62) of the first ball screw mechanism (66).

7. Electromechanical brake (10) according to any one of the preceding claims, characterized in that the first ball screw mechanism (66) has a ball return (78) made in the spindle (34).

8. Vehicle comprising an electromechanical brake (10) according to one of the re- previous demands.

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