Brake actuator for braking system, and braking system for vehicle

Abstract

To provide a brake actuator capable of neutralizing peak loads occurring when kinetic energy from rotation in a powertrain impacts an abruptly stiffening braking system.SOLUTION: A brake actuator (1) for a vehicle braking system comprises: a driving-side gear (3); a driven-side spindle nut, which is mechanically coupled to the driving-side gear (3) via a connecting element (4); and a clutch device, which is arranged between the driving-side gear (3) and the driven-side spindle nut and is formed to limit load torque acting on the driving-side gear to a predetermined limit value (TLimit).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a brake actuator for a braking system of a vehicle.The present invention also relates to a braking system for a vehicle. [Background technology]

[0002] Peak loads can occur in the brake actuator, for example, when the brake system stiffens or when the brake system is pushed uncontrolled towards the rear stop in a backed-up state. In this case, in the first case, the valve closure causes high stiffness changes in the brake system, especially in ABS control situations. During sudden braking, high rotational speeds are present in the driveline of the brake actuator. This causes the kinetic energy from the driveline rotations to impinge on the brake system, which stiffens suddenly, resulting in peak loads. It is essential to neutralize such peak loads.

[0003] For example, US Pat. No. 5,399,433 describes an assembly comprising an electromechanical brake force booster for an electrohydraulic vehicle brake system, the brake force booster having a clutch between the electric motor and the transmission to prevent overload damage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 046381 Summary of the Invention

[0005] The invention provides a brake actuator for a braking system of a vehicle with the features of claim 1 and a braking system for a vehicle with the features of claim 10 .

[0006] According to a first aspect of the invention, a brake actuator for a vehicle braking system is provided, the brake actuator comprising a drive gear, a driven spindle nut, the spindle nut being mechanically connected to the drive gear by a coupling element, and a clutch device arranged between the drive gear and the driven spindle nut and configured to limit a load torque acting on the drive gear to a predetermined limit value.

[0007] According to a second aspect of the present invention, there is provided a braking system comprising a brake actuator according to the present invention.

[0008] The idea behind the present invention is to protect the drive train of the brake actuator, in particular the drive gear, in a mechanical manner and method from loads that are critical for the components and could lead to damage in the drive train. In this case, the mechanical loads that occur in particular during dynamic impacts should be limited. During dynamic impacts, the load torque increases sharply. The clutch device allows the freewheeling of the drive gear when a certain limit value is reached or exceeded. When the certain limit value is exceeded, this freewheeling is terminated, so that the drive train can be driven slip-free.

[0009] Advantageous configurations and developments can be seen from the further dependent claims and from the description with reference to the drawing figures.

[0010] According to one embodiment, the drive gear is configured as a worm wheel and can be motor-driven by the worm shaft, so that a high transmission ratio in one gear stage from the worm shaft to the worm wheel can be achieved, and in addition there is a self-lock, i.e. the worm wheel cannot drive the worm shaft.

[0011] According to another embodiment, the clutch device is integrated into the drive gear, so that the ring gear of the gear can rotate relative to the hub of the gear. In particular, the ring gear can rotate irreversibly relative to the hub, which means that the induced rotation of the ring gear and the hub of the gear remains and does not return to the starting position that existed before the rotation. Furthermore, a new rotation is possible. In this way, a relatively large construction space of the brake actuator can be avoided and / or the number of additional parts can be reduced to the minimum necessary.

[0012] According to another embodiment, the clutch device is integrated in or attached to the coupling element, so that the gear can rotate relative to the spindle nut. In particular, the gear can rotate irreversibly relative to the spindle nut, which means that the generated rotation of the gear and the spindle nut relative to each other remains and does not return to the starting position that existed before the rotation. Furthermore, a new rotation is possible. This allows components that have already proven themselves for the intended application, such as coupling elements, to be used and adapted accordingly. This allows for a reduction in laborious or cost-intensive new developments.

[0013] According to another embodiment, the clutch device has a number of elastic transmission members, which are formed in such a way that when a predefined limit value is reached or exceeded, the clutch device switches from a locked state, in which the gear and the spindle nut are fixed to one another, to a slip state, in which the gear moves relative to the spindle nut. In this way, the clutch device can fully mechanically transmit the load torque in the locked state. In the slip state, the clutch device can also mechanically transmit a part of the load torque, but not beyond the predefined limit value. Furthermore, the clutch device can switch from the slip state to the locked state. Preferably, the longitudinal extension of the number of elastic transmission members is oriented in an angular range of about 15° to about 75°, in particular in an angular range of about 30° to about 60°, with respect to the radial direction of the gear. The predefined limit value can thereby be influenced by the orientation of the elastic transmission members. Furthermore, the orientation of the elastic transmission members can determine in which direction of movement the gear and the spindle nut can rotate relative to one another, so that in the opposite direction of movement no slip conditions can occur. Alternatively or additionally, the clutch device preferably has a protrusion, which is arranged and shaped in such a way that a number of elastic transmission members are supported on the protrusion for torque transmission in the restrained state. This allows the load torque to be transmitted more reliably.

[0014] According to another embodiment, the brake actuator further comprises a translatable spindle, which engages with a spindle nut and which is prevented from rotating about its longitudinal axis by an anti-rotation device. Preferably, the clutch device is integrated in or attached to the anti-rotation device. This allows components already proven for the intended application, e.g. anti-rotation devices, to be used and adapted accordingly. This reduces laborious or costly new developments and / or reduces the number of additional parts to a minimum required.

[0015] The invention will now be described with reference to the figures of the drawings. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view of a brake actuator according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic front view of a brake actuator drive train including a clutch device integrated into a drive side worm wheel according to one embodiment of the present invention; [Diagram 3] 1 is a schematic perspective view of a brake actuator drive train including a clutch device attached to a coupling element according to one embodiment of the present invention; FIG. [Figure 4A] 4 is a detailed view showing a locked state of a clutch device in an area indicated by an alphabet Y in the power transmission system shown in FIG. 2 or FIG. 3. [Figure 4B] 4 is a detailed view showing a slip state of a clutch device in the power transmission system shown in FIG. 2 or FIG. 3 in an area indicated by an alphabet Y. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] In the drawings, like numbers refer to the same or functionally identical components unless stated to the contrary.

[0018] FIG. 1 shows a perspective view of a brake actuator 1.

[0019] 1 for a brake system can be used in a vehicle / automobile, the applicability of the brake system with the brake actuator 1 being not limited to a certain vehicle type / automobile type of the vehicle / automobile, whereby the brake actuator 1 is exemplarily formed in particular as an electromechanical brake actuator, but can equally be formed as any type of motorized brake actuator.

[0020] The exemplary brake actuator 1 comprises a motor (not shown), a worm shaft 2, a worm wheel 3, a coupling element 4, a spindle nut 5, a translatable spindle 6, an anti-rotation device 7, a piston 8, a return spring 9 and a main brake cylinder 10. The motor, the worm shaft 2, the worm wheel 3, the coupling element 4, the spindle nut 5 and the translatable spindle 6 form a drive train which can move, for example, a piston 8 mechanically attached to the drive train relative to the main brake cylinder 10 in order to pump brake fluid. In the event of a dynamic impact in the drive train, for example, the volumetric flow of brake fluid is suddenly closed via a valve. This leads to a sudden increase in the stiffness of the brake actuator 1, which leads to peak loads in the drive train. The piston 8, which controls the volumetric flow of brake fluid, transmits the peak loads to the translatable spindle 6 due to the dynamic impact. The spindle 6 is engaged in the spindle nut 5 and continues to transmit the peak load, even to the worm wheel 3.

[0021] The anti-rotation device 7 prevents rotation of the translatable spindle 6 about its longitudinal axis.

[0022] FIG. 2 shows a schematic front view of the power transmission system of the brake actuator 1 including a clutch device 13 incorporated in the drive side worm wheel 3.

[0023] The exemplary power transmission system comprises a motor-driven worm shaft 2, a driving worm wheel 3, a coupling element 4, a driven spindle nut 5 and a spindle 6. The motor-driven worm shaft 2 can drive the driving worm wheel 3. The coupling element 4 is mechanically connected to the worm wheel 3. In addition, the driven spindle nut 5 is mechanically connected to the coupling element 4. The driven spindle nut 5 can drive the spindle 6. Furthermore, an anti-rotation device 7 and a main brake cylinder 10 of the brake actuator 1 are shown in FIG. 2.

[0024] The driving worm wheel 3 preferably has a ring gear and a hub. The ring gear has a number of teeth, and the teeth are arranged and formed so as to roll with the worm shaft 2.

[0025] A clutch device 13 is provided in the exemplary driving worm wheel 3 to limit the load torque applied to the worm wheel 3. The maximum load torque applied to the worm wheel 3 is a predetermined limit value T Limit The load torque acting on the worm wheel 3 corresponds in particular to the load torque acting on the ring gear. Limit In determining T, for example, the material properties of the material used in the worm wheel 3 and / or the wall thickness of the worm wheel 3 may be taken into account. In particular, the load capacity or the breaking strength of the ring gear or teeth of the worm wheel 3 may be determined so as to be within a certain limit value T Limit may be taken into consideration when determining.

[0026] The clutch device 13 is formed, for example, as a slip clutch. Viewed in the radial direction of the worm wheel 3, i.e. starting from the rotation axis of the worm wheel 3 towards the ring gear, the clutch device is arranged, for example, between the hub and the ring gear, it being irrelevant whether the clutch device 13 is arranged in the area of ​​the hub or in the area of ​​the ring gear or approximately centrally between the hub and the ring gear. The slip clutch is preferably arranged in the ring gear so that the slip clutch is engaged at a predetermined limit value T LimitWhen the predetermined limit value T is reached or exceeded, the ring gear is configured and designed to switch to a slip state in which the ring gear has a different, in particular a higher, rotational speed than the hub of the worm wheel 3 on the driving side. The slip clutch remains in the slip state until the worm shaft 2, which can be driven by a motor, reduces its kinetic energy, in particular due to friction in the slip clutch and / or braking of the worm shaft 2. Alternatively or additionally, the hub can increase its rotational speed as the mechanical resistance on the driven side decreases. Limit When this threshold is reached or exceeded, the slip clutch switches back to a locked condition in which the rotational speeds of the hub and ring gear are identical.

[0027] FIG. 3 shows a schematic perspective view of the drive train of a brake actuator 1 comprising a clutch device 13 attached to a coupling element 4 .

[0028] The exemplary power train shown in Fig. 3 has substantially the features of the power train according to the embodiment shown in Fig. 2. Furthermore, a clutch device 13 is exemplarily provided between the coupling element 4 and the spindle nut 5.

[0029] 4A and 4B are detailed views of the area indicated by the letter Y of the power transmission system shown in FIG. 2 or FIG. 3, respectively, with FIG. 4A showing the clutch device 13 in a locked state and FIG. 4B showing the clutch device 13 in a slipped state.

[0030] The illustrated excerpt with teeth represents the ring gear of the worm wheel 3 or the coupling element 4, regardless of the illustrated teeth in an exemplary manner. The illustrated longitudinal excerpt below represents the hub or spindle nut 5 of the worm wheel 3. Regardless of the arrangement of the clutch device 13, the clutch device 13 exemplarily comprises a number of elastic transmission members 11. The longitudinal extension of the elastic transmission members 11 is oriented, for example, at an angle of about 45° with respect to the radial direction of the worm wheel 3. The elastic transmission members 11 may be manufactured from an elastic material, for example plastic, silicone or a composite material. Alternatively or additionally, the elastic transmission members 11 may comprise structural elastic elements, for example springs.

[0031] Furthermore, the clutch device 13 may have protrusions 12. For example, the protrusions 12 are formed in a substantially triangular shape, but are not limited to a particular shape. What is important is, rather, that convex and concave portions of any shape are alternated. The protrusions 12 may be arranged and formed in such a way that a number of elastic transmission members 11 are supported on the protrusions 12 for torque transmission in the restrained state. Advantageously, the number of protrusions 12 is the same as the number of elastic transmission members 11 or a multiple thereof.

[0032] In FIG. 4A, the load torque is a predetermined limit value T Limit 4. The rotational speed of the worm wheel 3, the coupling member 4 and the spindle nut 5 is the same. There is no slip.

[0033] In FIG. 4B, the load torque is set to a predetermined limit value T Limit Higher or a given limit value T LimitA slip state is established accordingly, in which the worm wheel 3 exhibits a continuous rotation relative to the spindle nut 5, also called slip or freewheel. In this case, the clutch device 13 is engaged with the worm wheel 3 at a predetermined limit value T Limit may transmit a torque roughly equivalent to

[0034] Although the invention has been described in an exemplary manner with reference to the embodiments, the invention is not limited to the embodiments but can be modified in various ways, in particular combinations of the embodiments described above are also possible. [Explanation of symbols]

[0035] 1 Brake Actuator 2 Worm shaft 3 Worm wheels, gears 4. Joint elements, joint members 5 Spindle nut 6 Spindle 7 Anti-rotation device 8 Piston 9 Return spring 10 Main brake cylinder 11 Transmission components 12 Protrusion 13 Clutch device T Limit Limit

Claims

1. A brake actuator (1) for a braking system of a vehicle, comprising: A driving gear (3), a driven spindle nut (5) mechanically connected to the driving gear (3) by a coupling element (4); A clutch device (13) is disposed between the driving gear (3) and the driven spindle nut (5), and controls the load torque acting on the driving gear to a predetermined limit value (T Ｌｉｍｉｔ a clutch device (13) configured to restrict the Equipped with A brake actuator (1) for a braking system of a vehicle.

2. 2. The brake actuator (1) according to claim 1, wherein the drive gear (3) is configured as a worm wheel and can be driven by a motor via a worm shaft (2).

3. 3. A brake actuator (1) as claimed in claim 1 or 2, wherein the clutch device (13) is integrated into the drive-side gear (3) so that a ring gear of the gear (3) is rotatable, in particular irreversibly, relative to a hub of the gear (3).

4. A brake actuator (1) according to any one of claims 1 to 3, wherein the clutch device (13) is integrated in or attached to the coupling element (4), so that the gear (3) is rotatable, in particular irreversibly, relative to the spindle nut (5).

5. The clutch device (13) has a number of elastic transmission members (11), and the transmission members (11) are arranged to have a predetermined limit value (T Ｌｉｍｉｔ 5. A brake actuator (1) according to claim 1, wherein the clutch device (13) is configured to elastically deform so as to switch from a constrained state in which the gear (3) and the spindle nut (5) are fixed to each other to a slip state in which the gear (3) moves relative to the spindle nut (5) when a torque limiter (T) is reached or exceeded.

6. The brake actuator (1) according to claim 5, wherein the longitudinal extension of the multiple elastic transmission members (11) is oriented within an angular range of approximately 15° to approximately 75° with respect to a radial direction of the gear (3).

7. 7. The brake actuator (1) according to claim 5 or 6, wherein the clutch device (13) has a protrusion (12) arranged and configured such that a number of the elastic transmission members (11) are supported on the protrusion (12) for torque transmission in the restrained state.

8. 8. A brake actuator (1) according to any one of claims 1 to 7, further comprising a translatable spindle (6), the spindle (6) engaging the spindle nut (5), the spindle (6) being prevented from rotating about its longitudinal axis by an anti-rotation device (7).

9. 9. A brake actuator (1) according to claim 8, wherein the clutch device (13) is integrated in or attached to the anti-rotation device (7).

10. A brake system for a vehicle comprising a brake actuator (1) according to any one of claims 1 to 9.

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