Brake actuator for a brake system and brake system for a vehicle

Abstract

The invention relates to a brake actuator (1) for a brake system of a vehicle, comprising: a drive-side gearwheel (3); an output-side spindle nut (5) which is mechanically coupled to the drive-side gearwheel (3) by means of a connecting element (4); and a clutch device, which is arranged between the drive-side gearwheel (3) and the output-side spindle nut (5) and is designed to limit a load torque acting on the drive-side gearwheel to a predetermined limit value (TLimit).

Description

Technical Field

[0001] The invention relates to a brake actuator for a brake system for a vehicle. The invention also relates to a brake system for a vehicle. Background Art

[0002] For example, load peaks can occur in the brake actuator if the brake system becomes rigid or if the brake system is pressed uncontrollably against the rear stop in the standby state. In the first case, the closing of the valve leads to a large change in the rigidity of the brake system, especially in the case of ABS control. During rapid braking, the rotation speed in the drive train of the brake actuator is very high. As a result, the kinetic energy of the rotation of the drive train strikes the suddenly rigid brake system, which results in load peaks. Such load peaks need to be compensated.

[0003] For example, patent document WO 2017 / 046381 A1 describes an assembly for an electrohydraulic vehicle brake system having an electromechanical brake booster, wherein the brake booster has a clutch located between the electric motor and the gear mechanism to prevent overload damage. Summary of the invention

[0004] The invention provides a brake actuator for a brake system of a vehicle having the features of claim 1 and a brake system for a vehicle having the features of claim 10 .

[0005] According to a first aspect of the present invention, a brake actuator for a brake system of a vehicle is provided. The brake actuator has a gear on the drive side and a lead screw nut on the output side, and the lead screw nut is mechanically coupled to the gear on the drive side by means of a connecting element. The brake actuator also has a clutch device, which is arranged between the gear on the drive side and the lead screw nut on the output side and is configured to limit the load torque acting on the gear on the drive side to a predetermined limit value.

[0006] According to a second aspect of the invention, a brake system having a brake actuator according to the invention is provided.

[0007] The basic idea of ​​the invention is to mechanically protect the drive train of the brake actuator, in particular the gears on the drive side, from component-critical loads that could damage the drive train. In particular, the mechanical loads that occur during dynamic shocks are to be limited. During dynamic shocks, the load moments increase rapidly. When a predetermined limit value is reached or exceeded, the clutch device can cause the gears on the drive side to idle. When the predetermined limit value is fallen below, the idle rotation ends, so that the drive train can be driven without slip.

[0008] Advantageous embodiments and developments emerge from the further dependent claims and from the description with reference to the figures of the drawing.

[0009] According to one embodiment, the drive-side gear is designed as a worm wheel and can be driven mechanically by the worm. As a result, a very high transmission ratio can be achieved in the gear mechanism stage (transmission stage) from the worm to the worm wheel, wherein there is also self-locking, that is, the worm wheel cannot drive the worm.

[0010] According to another embodiment, the clutch device is integrated into the gear on the drive side so that the toothed ring of the gear can be twisted relative to the hub of the gear. In particular, the toothed ring can be twisted irreversibly relative to the hub, which means that the resulting twisting of the toothed ring and the hub of the gear relative to each other is maintained and does not return to a starting position given before the twisting. Furthermore, a twisting is also possible. In this way, a large installation space for the brake actuator can be avoided and / or additional components can be reduced to the minimum necessary number.

[0011] According to another embodiment, the clutch device is integrated in the connecting element or arranged on the connecting element so that the gear can be twisted relative to the spindle nut. In particular, the gear can be twisted irreversibly relative to the spindle nut, which means that the resulting twisting of the gear and the spindle nut relative to each other is maintained and does not return to the starting position given before the twisting. In addition, it is also possible to twist again. As a result, components that have already proven suitable for the intended application, such as connecting elements, can be used and adjusted accordingly. This can reduce expensive new developments.

[0012] According to another embodiment, the clutch device has a plurality of elastic transmission components, which are configured to be elastically deformed when a predetermined limit value is reached or exceeded, so that the clutch device switches from an attached state in which the gear and the lead screw nut are fixed to each other to a sliding state in which the gear moves relative to the lead screw nut. In this way, the clutch device can completely mechanically transmit the load torque in the attached state. Even in the sliding state, the clutch device can also mechanically transmit a portion of the load torque, but it cannot exceed the predetermined limit value. In addition, the clutch device can be switched from the sliding state to the attached state. Preferably, a plurality of elastic transmission components are oriented in their longitudinal range with an angle range of about 15° to about 75°, especially an angle range of about 30° to about 60° relative to the radial direction of the gear. Thus, the predetermined limit value can be influenced by the orientation of the elastic transmission component. In addition, the orientation of the elastic transmission component can determine in which direction of movement the gear and the lead screw nut can be twisted relative to each other, and therefore no sliding state will occur in the opposite direction of movement. Alternatively or additionally, the clutch device preferably has a projection, which is arranged and configured such that a plurality of elastic transmission members are supported on the projection in the attached state to transmit torque, thereby enabling the load torque to be transmitted more reliably.

[0013] According to another embodiment, the brake actuator also has a non-translationally movable spindle, which engages with a spindle nut, wherein the spindle is prevented from rotating about its longitudinal axis by means of a rotational protection device. Preferably, the clutch device is integrated into the rotational protection device or is arranged at the rotational protection device. As a result, components that have proven suitable for the intended application, such as the rotational protection device, can be used and adjusted accordingly. As a result, expensive new developments can be reduced and / or additional components can be reduced to the minimum necessary number. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention is explained below with reference to the accompanying drawings, in which:

[0015] Figure 1 shows a perspective view of a brake actuator according to an embodiment of the present invention;

[0016] Figure 2 A front view of a schematic illustration of a drive train of a brake actuator according to an embodiment of the invention is shown, the brake actuator having a clutch device integrated in a worm gear on the drive side;

[0017] Figure 3 A perspective view showing a schematic representation of a drive train of a brake actuator according to an exemplary embodiment of the invention, the brake actuator having a clutch device arranged on a connecting element;

[0018] Figure 4A Shows Figure 2 and Figure 3 A detailed view of the area of ​​the drive train indicated by the letter Y, showing the engagement state of the clutch device;

[0019] Figure 4B Shows Figure 2 and Figure 3 A detailed view of the area of ​​the drive train marked by the letter Y is shown, in which the slip state of the clutch device is shown. DETAILED DESCRIPTION

[0020] In the figures, identical reference signs denote identical or functionally identical components, unless otherwise stated.

[0021] Figure 1 A perspective view of a brake actuator 1 is shown.

[0022] Figure 1 The schematically illustrated brake actuator 1 for a brake system can be used on a vehicle / motor vehicle, wherein the applicability of a brake system having the brake actuator 1 is not limited to a specific vehicle type / motor vehicle type. The brake actuator 1 is designed, for example, in particular as an electromechanical brake actuator, but can also be designed as any type of motorized brake actuator.

[0023] The exemplary brake actuator 1 comprises a motor (not shown), a worm 2, a worm wheel 3, a connecting element 4, a spindle nut 5, a non-translationally movable spindle 6, a rotation prevention device 7, a piston 8, a return spring 9 and a master brake cylinder 10. Here, the motor, the worm 2, the worm wheel 3, the connecting element 4, the spindle nut 5 and the non-translationally movable spindle 6 form a drive train. This drive train can, for example, move a piston 8 mechanically mounted thereon relative to the master brake cylinder 10 to convey brake fluid. In the event of a dynamic shock to the drive train, the volume flow of brake fluid through a valve can be suddenly closed, for example. This suddenly increases the stiffness of the brake actuator 1, which leads to load peaks in the drive train. The piston 8, which controls the volume flow of brake fluid, transfers the load peak to the non-translationally movable spindle 6 due to the dynamic shock. The spindle 6 engages in the spindle nut 5 and further transfers the load peak to the worm wheel 3.

[0024] The anti-rotation device 7 prevents the non-translational threaded spindle 6 from rotating about the longitudinal axis of the non-translational threaded spindle 6 .

[0025] Figure 2 A schematic front view of a drive train of a brake actuator 1 is shown, which has a clutch device 13 integrated in the drive-side worm gear 3 .

[0026] The exemplary transmission system has a motorized drivable worm 2, a worm wheel 3 on the drive side, a connecting element 4, a spindle nut 5 on the output side, and a screw 6. Here, the motorized drivable worm 2 can drive the worm wheel 3 on the drive side. The connecting element 4 is mechanically connected to the worm wheel 3. In addition, the spindle nut 5 on the output side is mechanically connected to the connecting element 4. The spindle nut 5 on the output side can drive the screw 6. In addition, Figure 2 2 , the anti-rotation device 7 and the master brake cylinder 10 of the brake actuator 1 are shown.

[0027] The drive-side worm wheel 3 preferably has a toothed ring and a hub. The toothed ring includes a plurality of teeth that are arranged and configured to roll together with the worm 2 .

[0028] In the exemplary drive-side worm gear 3 , the clutch device 13 is provided for limiting the load moment on the worm gear 3 . Limit The maximum load moment acting on the worm wheel 3 is determined. The load moment acting on the worm wheel 3 is particularly consistent with the load moment acting on the gear ring. When determining the predetermined limit value T Limit For example, the material properties of the material used in the worm wheel 3 and / or the wall thickness of the worm wheel 3 can be taken into account when determining the predetermined limit value T Limit When , the load-bearing capacity or the breaking strength of the toothed ring of the worm wheel 3 , or more precisely the teeth, can be taken into account.

[0029] The clutch device 13 is designed, for example, as a slip clutch. Viewed in the radial direction of the worm wheel 3, i.e. starting from the axis of rotation of the worm wheel 3 towards the toothed ring, the clutch device is arranged, for example, between the hub and the toothed ring, wherein it is irrelevant whether the clutch device 13 is arranged in the region of the hub, in the region of the toothed ring or approximately midway between the hub and the toothed ring. The slip clutch is preferably designed and constructed such that when a predetermined limit value T in the toothed ring is reached or exceeded, the clutch device 13 is released. Limit The slip clutch switches to a slipping state in which the toothed ring has a different rotational speed, in particular a higher rotational speed, than the hub of the worm wheel 3 on the drive side. The slip clutch remains in the slipping state until the worm 2, which can be driven mechanically, for example, has reduced its kinetic energy, in particular due to friction in the slip clutch and / or braking of the worm 2. Alternatively or additionally, the hub can increase its rotational speed when the mechanical resistance on the output side decreases. When a predetermined limit value T is reached or falls below, the rotation speed of the hub can be increased. Limit When the slip clutch switches back to the sticking state, the hub and the gear ring rotate at the same speed.

[0030] Figure 3 A perspective view of a schematic representation of a drive train of a brake actuator 1 is shown, which has a clutch device 13 arranged on a connecting element 4 .

[0031] according to Figure 3 The exemplary transmission system of Figure 2 Furthermore, the clutch device 13 is exemplarily arranged between the connecting element 4 and the spindle nut 5 .

[0032] Figure 4A and Figure 4B They are shown respectively Figure 2 and Figure 3 A detailed view of the area of ​​the drive train marked by the letter Y is shown, wherein Figure 4A shows the attachment state of the clutch device 13 and Figure 4B The slip state of the clutch device 13 is shown.

[0033] Regardless of the teeth shown by way of example, the cutout shown with the teeth represents the toothed ring or the connecting element 4 of the worm wheel 3. The elongated cutout shown below represents the hub or the lead screw nut 5 of the worm wheel 3. Regardless of how the clutch device 13 is arranged, the clutch device 13 includes, for example, a plurality of elastic transfer members 11. The elastic transfer member 11 is oriented at an angle of approximately 45° relative to the radial direction of the worm wheel 3 over its longitudinal extent, for example. The elastic transfer member 11 can be made of an elastic material, such as plastic, silicone or a composite material. Alternatively or additionally, the elastic transfer member 11 can have a structural elastic element, such as a spring.

[0034] In addition, the clutch device 13 can have a protrusion 12. For example, the protrusion 12 is basically triangular in shape, but is not limited to a specific shape. More importantly, some form of protrusions and recesses appear alternately. The protrusion 12 can be arranged and configured so that a plurality of elastic transfer members 11 are supported at the protrusion 12 in the attached state to transfer torque. Advantageously, the number of protrusions 12 is equal to the number of elastic transfer members 11 or a multiple thereof.

[0035] exist Figure 4A The load moment is less than the predetermined limit value T Limit Accordingly, a bonded state is present, in which the drive-side worm wheel 3 , more precisely its toothed ring, and the spindle nut 5 are fixed to one another. The rotational speeds of the worm wheel 3 , the connecting element 4 , and the spindle nut 5 are the same. There is no slippage.

[0036] exist Figure 4B The load moment is higher than the predetermined limit value T Limit Or equal to the predetermined limit value T Limit . Accordingly, a sliding state is presented, in which the worm wheel 3 has a continuous torsion relative to the spindle nut 5. This continuous torsion is called slip or idling. In this case, the clutch device 13 can also transmit a torque that is different from the predetermined limit value T Limit Roughly the same.

[0037] Although the present invention has been explained above by way of example based on embodiments, the present invention is not limited thereto but can be modified in many ways. In particular, combinations of the above embodiments are also conceivable.

Claims

1. A brake actuator (1) for a brake system of a vehicle, the brake actuator comprising: A gear (3) on the driving side; a spindle nut (5) on the output side, which is mechanically coupled to the gear (3) on the drive side by means of a connecting element (4); and A clutch device (13) is arranged between the gear (3) on the drive side and the spindle nut (5) on the output side and is configured to limit the load torque acting on the gear (3) on the drive side to a predetermined limit value (T Limit ).

2. The brake actuator (1) according to claim 1, wherein: The drive-side gear wheel (3) is designed as a worm wheel and can be driven mechanically by the worm (2).

3. The brake actuator (1) according to claim 1 or 2, wherein: The clutch device (13) is integrated into the drive-side gear (3) in such a way that the toothed ring of the gear (3) can be rotated relative to the hub of the gear (3), in particular can be rotated irreversibly.

4. The brake actuator (1) according to any one of the preceding claims, wherein: The clutch device (13) is integrated into the connecting element (4) or is arranged on the connecting element (4) in such a way that the gear wheel (3) can be rotated relative to the spindle nut (5), in particular can be rotated irreversibly.

5. Brake actuator (1) according to any one of the preceding claims, wherein: The clutch device (13) has a plurality of elastic transmission components (11), wherein the elastic transmission components are configured to Limit ), elastic deformation occurs when the clutch device (13) is engaged, so that the clutch device (13) switches from an attached state in which the gear (3) and the lead screw nut (5) are fixed to each other to a sliding state in which the gear (3) moves relative to the lead screw nut (5).

6. The brake actuator (1) according to claim 5, wherein: A plurality of elastic transfer members (11) are oriented in their longitudinal extent at an angle ranging from about 15° to about 75° relative to the radial direction of the gear (3).

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

8. The brake actuator (1) according to any one of the preceding claims, further comprising a non-translational lead screw (6) which engages with the lead screw nut (5), wherein: The threaded spindle (6) is secured against rotation about its longitudinal axis by means of a rotation prevention device (7).

9. The brake actuator (1) according to claim 8, wherein: The clutch device (13) is integrated into the anti-rotation device (7) or is arranged on the anti-rotation device (7).

10. A brake system for a vehicle having a brake actuator (1) according to any one of the preceding claims.

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