Thread transmission device, brake actuator and electromechanical brake
Patent Information
- Application Number
- CN202510957647.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-07-18
- Filing Date
- 2025-07-11
- Publication Date
- 2026-01-20
AI Technical Summary
The existing threaded drive mechanism of the electromechanical vehicle brake is prone to jamming when the main shaft moves to the base of the main shaft nut, resulting in friction and delay, and the need for additional stop components increases the size and weight of the device.
Design a threaded transmission device, in which the main shaft nut has an annular groove and a stop accessory. The stop wall is set inside the device to prevent jamming and without increasing the structural space. The axial movement is stopped by the cooperation of the groove and the stop accessory.
It enables simple manufacturing without additional parts and structural space, prevents jamming, ensures smooth axial movement, and keeps the device lightweight.
Smart Images
Figure CN121363597A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The invention relates to a screw drive, in particular a ball screw drive, for an electromechanical brake, having a pot-shaped spindle nut having a base and a circumferential wall, which on the inside has a thread. Furthermore, the screw drive has a spindle having an outer thread, which extends into the interior of the spindle nut, and a drive geometry on the spindle for transmitting a rotary motion to the spindle, which moves the spindle nut axially via the outer thread. The spindle has an end face, which faces the inside of the base of the spindle nut. Furthermore, the invention relates to a brake actuator and to an electromechanical brake having such a screw drive. BACKGROUND
[0002] In screw drives, in particular ball screw drives, used in brake actuators for electromechanical vehicle brakes, the spindle nut usually forms the brake piston. This means that the spindle nut applies the brake pads to the brake rotor. In order to allow the spindle nut, i.e. the brake piston, to move axially along the spindle, the spindle nut is guided so as to be fixed against rotation.
[0003] Alternatively, the spindle nut can also be designed separately from the brake piston, the spindle nut being supported on the brake piston and moving the brake piston in order to apply the brake pads to the brake rotor.
[0004] In order to prevent the screw drive from jamming when the spindle is moved against the base of the spindle nut, a stop can be provided, which stops the movement of the spindle nut. These are usually additional components, which increase the size of the screw drive and its weight.
[0005] Due to the high friction between the base of the spindle nut and the end face of the spindle, such a jamming can only be released with difficulty and can lead to a delay in the subsequent braking process. SUMMARY
[0006] It is therefore an object of the present invention to provide a screw drive for an electromechanical brake, which can be produced as simply as possible and does not require additional weight and does not require an increased installation space. Furthermore, it is an object of the present invention to provide a brake actuator and an electromechanical brake having such a screw drive.
[0007] According to the application, this object is achieved by a screw transmission for an electromechanical brake, which has a pot-shaped spindle nut having a base and a circumferential wall, which on the inside has a thread. Furthermore, the screw transmission comprises a spindle having an outer thread, which extends into the interior of the spindle nut, and a transmission geometry on the spindle for transmitting rotational movements to the spindle, which only the outer thread moves the spindle nut axially. The spindle has an end face, which faces the inside of the base of the spindle nut. The end face has at least one recess in the shape of an annular segment, which extends concentrically to the central rotational axis of the screw transmission and ends in the circumferential direction in a stop wall, which terminates the recess. For this purpose, the base of the spindle nut has at least one stop attachment, which protrudes towards the end face and, at the end of the axial movement of the spindle nut relative to the spindle, enters the recess and strikes the stop wall, so that the movement of the device is stopped.
[0008] Alternatively, the base of the spindle nut has at least one recess in the shape of an annular segment, which extends concentrically to the central rotational axis of the screw transmission and ends in the circumferential direction in a stop wall, which terminates the recess. The end face of the spindle has at least one stop attachment, which protrudes towards the base of the spindle nut and, at the end of the axial movement of the spindle nut relative to the spindle, enters the recess, strikes the stop wall and stops the movement of the spindle.
[0009] In principle, the arrangement of the stop attachment on the base of the spindle nut and the provision of the recess on the end face of the spindle are preferred, since the base of the spindle nut is usually very thin and the recess additionally weakens the base of the spindle nut.
[0010] In other words, the stop mechanism is integrated into the screw transmission, wherein a recess with a stop wall is provided in one part of the screw transmission and a stop attachment is provided in another part. Due to the use of the recess, the stop wall is provided within the components of the screw transmission, so that no dimensions are increased in the axial or radial direction. Thus, a clearance can be ensured and the screw transmission can be prevented from jamming, without the screw transmission requiring more installation space.
[0011] The spindle nut can form a brake piston, so that the axial movement of the brake piston can be achieved directly by the spindle and no additional components are required.
[0012] Preferably, the transmission geometry is present on a shaft, which protrudes axially from the remainder of the spindle. As a result, the spindle can be electrically actuated directly or indirectly via a gear mechanism. The transmission geometry can in particular be formed integrally with the spindle, so that no additional components are required to drive the spindle.
[0013] According to one embodiment, at least two annular segment-shaped recesses and at least two stop attachments are provided, wherein each stop attachment is arranged in such a way that it can only enter its own recess. As a result, it can be ensured that the rotational movement of the spindle is stopped at the desired time even in the event of damage to the stop attachment. Furthermore, due to the double protection with at least two stop mechanisms, a distribution of forces can be achieved, so that the service life of the thread transmission can be extended.
[0014] It can be provided that the at least two stop attachments are radially offset with respect to one another.
[0015] Alternatively, it can be provided that the at least two stop attachments are next to one another in the circumferential direction and are separated from one another in the circumferential direction by a stop wall. The selected arrangement of the at least two stop attachments and the selected arrangement of the at least two recesses in a corresponding manner depends on the geometry of the thread transmission, in particular on the radial dimension of the thread transmission.
[0016] According to a preferred embodiment, the at least one annular segment-shaped recess is at a distance from the circumference of the end face or the circumferential wall. Thus, the stop attachment is guided within the recess until the stop attachment comes into contact with the stop wall. This ensures that the stop wall for the stop attachment does not expand the respective component along the central rotational axis.
[0017] In order to obtain the annular segment-shaped recess, the respective thread transmission component can be manufactured, for example, by cold forming or injection molding. Alternatively, the annular segment shape can also be milled in the subsequent manufacture of the thread transmission.
[0018] According to one embodiment, the spindle has a cavity, in particular a cylindrical cavity, starting from the end face. In this way, the weight of the thread transmission can be reduced.
[0019] Preferably, the annular segment-shaped recess extends over at least 120°, so that an unobstructed entry of the stop attachment into the recess is ensured. Thus, the stop mechanism of the thread transmission can be ensured independently of the assembly of the thread transmission, while the base of the spindle nut does not come into direct axial contact with the end face and effectively prevents jamming of the thread transmission.
[0020] According to a preferred embodiment, the stop wall merges smoothly into the rest of the base of the spindle nut. This ensures that no additional installation space along the central rotational axis is required by providing the stop wall, since the stop wall is completely located in the recess, i.e. the recess, in the base or the end face of the spindle nut.
[0021] According to a preferred embodiment, the stop wall has a stop surface in the form of a cylindrical circular segment surface and the stop attachment has a complementary mating surface. By means of the complementary surfaces, the best possible transmission of forces is ensured, so that uneven wear of the stop surface does not occur. Furthermore, it can thus be ensured that the stop attachment does not slip on the stop wall.
[0022] The screw drive is preferably a ball screw drive, i.e. has balls between the threads.
[0023] According to the application, this object is also achieved by a brake actuator of an electromechanical brake, which comprises a brake caliper in which an intermediate space for a brake rotor is formed and in which the brake caliper has brake pads which can be applied to the brake rotor. Furthermore, the brake actuator comprises a screw drive as described above and an electric motor which is coupled in a driving manner to the drive geometry of the spindle. Thereby, a rotational movement is transmitted to the spindle so that the spindle nut can be moved along the central rotational axis between a retracted position and an extended position by the rotational movement of the spindle. In other words, the brake actuator can move the spindle nut into the extended position, in which the brake pads are applied to the brake rotor, or into the retracted position, in which the vehicle brake is released, via the rotational movement of the spindle.
[0024] Furthermore, according to the application, this object is achieved by an electromechanical brake having a brake caliper in which an intermediate space for a brake rotor is formed and in which the brake caliper has brake pads which can be applied to the brake rotor, and a brake actuator as described above for moving the brake pads and engaging the brake.
[0025] By using the screw drive described above in the brake actuator and thus in the electromechanical brake, it is ensured that in the retracted position, i.e. in the case of releasing the brake, the necessary play can be ensured and a jamming of the screw drive does not occur, so that the extended position, i.e. the engaged position, can be reached at any time when actuating the brake.
[0026] In order to ensure the movement of the spindle nut, the electromechanical brake preferably has an anti-rotation device which prevents the spindle nut from rotating relative to the central rotational axis of the screw drive, so that the rotational movement of the spindle ensures the axial movement of the spindle nut. The rotational locking of the spindle nut can be realized, for example, by means of a pin. BRIEF DESCRIPTION OF DRAWINGS
[0027] Further advantages and features of the application result from the following description and the referenced drawings. In the drawings:
[0028] Figure 1a perspective partial view of an electromechanical brake according to the present application is shown;
[0029] Figure 2 a perspective view of a ball screw drive according to the present application is shown;
[0030] Figure 3 a perspective view of Figure 2 a spindle of the ball screw drive shown in
[0031] Figure 4 a perspective view of Figure 2 a brake piston of the ball screw drive shown in DETAILED DESCRIPTION
[0032] Figure 1 A brake actuator 10 for an electromechanical brake 12 of a vehicle is shown. The electromechanical brake 12 comprises a brake caliper 14 in which an intermediate space 16 for braking a rotor (not shown) is formed. Furthermore, the electromechanical brake 12 comprises a ball screw drive 18 having a rotatably mounted spindle 20 on which a one-sided open spindle nut 22 is mounted. Thus, the spindle nut 22 forms a pot-shaped brake piston 24 comprising a piston base 26 and a circumferential wall 28 (see Figure 4 ) and for applying brake pads 30 to the brake rotor.
[0033] The axial displacement of the brake piston 24 from a retracted position to an extended position and vice versa is effected by a rotation of the spindle 20. In fact, an outer thread 32 is formed on a circumferential surface of the spindle 20 and an inner thread 34 is formed on the inside of the circumferential wall 28 of the brake piston 24, so that at least one thread track is formed by the outer thread 32 and the inner thread 34 of the brake piston 24. A plurality of balls 36 is guided in the thread track, so that a rotation of the spindle 20 causes an axial displacement of the brake piston 24 along a central rotation axis of the ball screw drive 18.
[0034] The outer thread 32 and the inner thread 34 can also be multi-start threads, so that a plurality of thread tracks is formed by the outer thread 32 and the inner thread 34, in which a multitude of balls 36 is guided.
[0035] In order to allow an axial movement of the brake piston 24 along the spindle 20, the brake piston 24 is guided in the electromechanical brake 12 so as to be fixed against rotation, for example by means of a pin. In order to drive the spindle 20, the spindle 20 has a transmission geometry 38. Via the transmission geometry 38, the spindle 20 is coupled via a gear mechanism 40 to Figure 1The motor is not visible in the figure. Alternatively, the spindle 20 can also be coupled directly to the motor via the transmission geometry 38.
[0036] From Figure 2 it can be seen that the transmission geometry 38 is a shaft 42, which projects axially from the rest of the spindle 20 and preferably has a toothing 44 in order to be coupled to the gear mechanism 40 or to the motor.
[0037] In Figure 1 and Figure 2 it can also be seen that the spindle 20 projects with its outer thread 32 into the interior of the brake piston 24.
[0038] In Figure 3 it can be seen that the spindle 20 has an end face 46 facing the interior of the piston base 26. On the end face 46 of the spindle 20, a return channel 48 is shown, which is axially closed, in order to transport the ball 36. Furthermore, a cavity 50 is provided, which extends from the end face 46 in the direction of the transmission geometry 38. The cavity 50 is preferably cylindrical and serves to reduce the weight of the ball screw drive.
[0039] In Figure 3 it can also be seen that in the end face 46 a recess 52 is provided in the shape of an annular segment, which extends concentrically to the central rotational axis of the ball screw drive 18. The recess 52 ends in a stop wall 54 in the circumferential direction, which thus circumferentially terminates the recess 52. The stop wall 54 merges smoothly into the rest of the end face 46, so that the axial length of the spindle 20 is not lengthened despite the provision of the stop wall 54.
[0040] As can also be seen in Figure 3 the annular segment-shaped recess 52 is at a distance from the circumference of the end face 46. The recess 52 is thus formed only in the end face 46 of the spindle 20. Furthermore, the recess 52 extends over at least 120°. The stop wall 54 formed in the recess 52 has a stop surface 56, which preferably has the form of a cylindrical circular segment surface.
[0041] In Figure 4In detail, the brake piston 24 is shown, which has a stop attachment 58 that is complementary to the stop wall 54 of the spindle 20. It can be seen that the stop attachment 58 protrudes in the direction of the end face 46 from the piston base 26. The stop attachment 58 is placed in such a way that it can enter the recess 52 in order to stop the axial movement of the brake piston 24 as well as the rotational movement of the spindle 20. The stop attachment 58 is at a distance from the central rotational axis, which corresponds to the distance of the recess 52 from the central rotational axis. The face of the stop attachment 58 that comes into contact with the stop wall 54 is a mating surface 60 that is complementary to the stop surface 56, through which a form fit between the stop wall 54 and the stop attachment 58 is produced at the end of the axial movement of the brake piston 24 in the direction of the spindle 20.
[0042] When the electromechanical brake 12 is actuated and thus the brake actuator 10 is actuated, then the spindle 20 is electrically driven via the transmission geometry 38 and a rotational movement of the spindle 20 occurs. Due to the rotational movement of the spindle 20 about the central rotational axis of the ball screw transmission 18, the balls 36 roll along the thread tracks defined by the outer thread 32 and the inner thread 34 and move towards the piston base 26. There, they are picked up by the return channel 48, guided towards the rear spindle end and inserted into the thread tracks again.
[0043] Since the brake piston 24 is mounted in the brake caliper 14 so as to be fixed against rotation, an axial movement of the brake piston 24 along the spindle 20 in the direction of the brake pad 30 occurs. When the brake piston 24 comes into contact with the brake pad 30, the brake piston 24 exerts a force onto the brake pad 30, so that the brake pad 30 moves in the direction of the brake rotor and the electromechanical brake 12 is actuated. When the electromechanical brake 12 is released, the spindle 20 is driven in the opposite direction, so that the brake piston 24 completes an axial movement relative to the spindle 20.
[0044] At the end of this axial movement, the stop attachment 58 of the brake piston 24 enters the recess 52 on the end face 46 of the spindle 20. As a result, a form fit is formed in the recess 52 between the stop attachment 58 and the stop wall 54, so that the movement of the spindle 20 is stopped. The brake piston 24 is stopped in such a way that the axial clearance between the brake piston 24 and the spindle 20, i.e. between the end face 46 and the piston base 26, continues to be ensured and a jamming of the ball screw transmission 18 is prevented.
[0045] Not shown in the drawing is that, according to a further embodiment of the ball screw transmission 18, at least two recesses 52 of the annular segment shape and / or at least two stop attachments 58 can be provided. The stop attachments 58 are arranged in such a way that they can each only enter the provided recess 52.
[0046] Depending on the configuration of the ball screw drive 18, the stop attachment 58 and thus also the recess 52 can be radially offset relative to one another or, alternatively, immediately adjacent to one another in the circumferential direction, such that they are separated from one another in the circumferential direction by the stop wall 54. By providing a plurality of stop attachments 58 and recesses 52, a more even force distribution can be achieved and additional protection can be provided.
[0047] According to an alternative embodiment, which is likewise not shown in the figures, a recess 52 in the shape of an annular segment, which extends concentrically to the central rotational axis of the ball screw drive 18, is provided in the piston base 26, such that the stop wall 54 is also provided in and merges smoothly into the piston base 26. The spindle 20 in this embodiment thus has at least one stop attachment 58, which projects toward the piston base 26 and can engage in the recess 52 in the piston base 26.
[0048] Alternatively, the ball screw drive can also be designed as a conventional threaded drive without balls but with threads that slide on one another.
Claims
1. Threaded transmission (18) for an electromechanical brake (12), the threaded transmission (18) having: a pot-shaped spindle nut (22) having a base and a circumferential wall (28) with an inner thread (34) on the inner side; a spindle (20) having an outer thread (32) with which the spindle (20) projects into the interior of the spindle nut (22) and a drive geometry (38) on the spindle (20) for transmitting rotational movement to the spindle (20), which moves the spindle nut (22) axially via the outer thread (32), wherein the spindle (20) having an end face (46) facing the inner side of the base of the spindle nut (22), wherein: either the end face (46) has at least one annular segment-shaped recess (52) which extends concentrically to the central rotational axis of the threaded transmission (18) and ends circumferentially in a stop wall (54) which terminates the recess (52) and the base of the spindle nut (22) has at least one stop attachment (58) which protrudes towards the end face (46) and which, at the end of the axial movement of the spindle nut (22) relative to the spindle (20), enters the recess (52), hits the stop wall (54) and stops the movement of the spindle (20), or, conversely, the base of the spindle nut (22) has at least one annular segment-shaped recess which extends concentrically to the central rotational axis of the threaded transmission (18) and ends circumferentially in a stop wall (54) which terminates the recess and the end face (46) of the spindle (20) has at least one stop attachment which protrudes towards the base of the spindle nut (22) and which, at the end of the axial movement of the spindle nut (22) relative to the spindle (20), enters the recess, hits the stop wall and stops the movement of the spindle (20).
2. Threaded drive (18) according to claim 1, characterized in that the spindle nut (22) is a pot-shaped brake piston (24) having a piston base (26).
3. Threaded transmission (18) according to any one of claims 1 and 2, characterized in that the transmission geometry (38) is present on a shaft (42) which protrudes axially from the remainder of the spindle (20).
4. Threaded transmission (18) according to any of the preceding claims, characterized in that At least two annular segment-shaped recesses and / or at least two stop attachments are provided, wherein each stop attachment (58) is arranged such that it can only enter its own recess (52).
5. Threaded drive (18) according to claim 4, characterized in that The at least two stop attachments are radially offset relative to one another.
6. Threaded drive (18) according to claim 4, characterized in that The at least two stop attachments are immediately adjacent to one another in the circumferential direction and are separated from one another in the circumferential direction by a stop wall.
7. Threaded drive (18) according to any of the preceding claims, characterized in that The at least one annular segment-shaped recess (52) is at a distance from the periphery of the end face (46) or the circumferential wall (28).
8. Threaded transmission (18) according to any one of the preceding claims, characterized in that The spindle (20) has a cavity (50), in particular a cylindrical cavity (50), starting from the end face (46).
9. Threaded transmission (18) according to any of the preceding claims, characterized in that The at least one annular segment-shaped recess (52) extends over at least 120°.
10. Threaded drive (18) according to any of the preceding claims, characterized in that The stop wall (54) merges smoothly into the remainder of the base of the spindle nut (22) or the end face (46). the spindle nut (22) is a pot-shaped brake piston (24) having a piston base (26). the transmission geometry (38) is present on a shaft (42) which protrudes axially from the remainder of the spindle (20). At least two annular segment-shaped recesses and / or at least two stop attachments are provided, wherein each stop attachment (58) is arranged such that it can only enter its own recess (52). The at least two stop attachments are radially offset relative to one another. The at least two stop attachments are immediately adjacent to one another in the circumferential direction and are separated from one another in the circumferential direction by a stop wall. The at least one annular segment-shaped recess (52) is at a distance from the periphery of the end face (46) or the circumferential wall (28). The spindle (20) has a cavity (50), in particular a cylindrical cavity (50), starting from the end face (46). The at least one annular segment-shaped recess (52) extends over at least 120°. The stop wall (54) merges smoothly into the remainder of the base of the spindle nut (22) or the end face (46).
11. Threaded drive (18) according to any of the preceding claims, characterized in that The stop wall (54) has a stop surface (56) in the form of a cylindrical circular segment surface and the stop attachment (58) has a complementary mating surface (60).
12. Threaded drive (18) according to any of the preceding claims, characterized in that The screw drive (18) is a ball screw drive.
13. A brake actuator (10) of an electromechanical brake (12) having a brake caliper (14) in which an intermediate space (16) for a brake rotor is formed and in which the brake caliper (14) has brake pads (30) that can be applied to the brake rotor, The brake actuator (10) comprises: The screw drive (18) according to any one of the preceding claims; An electric motor coupled in a driving sense to a drive geometry (38) of the spindle (20) in order to transmit rotational movement to the spindle (20) such that the brake piston (24) can be moved along the central rotation axis between a retracted position and an extended position by the rotational movement of the spindle (20).
14. An electromechanical brake (12) having: a brake caliper (14) in which an intermediate space (16) for a brake rotor is formed and in which the brake caliper (14) has brake pads (30) that can be applied to the brake rotor; and The brake actuator (10) according to claim 13 for moving the brake pads (30) and actuating the electromechanical brake (12).