Electromechanical brake actuator, drive assembly for electromechanical brake actuator, and method for operating electromechanical brake actuator

Abstract

A drive assembly for an electromechanical brake actuator, comprising: an electric motor; a transmission mechanism kinematically coupled to the motor, the transmission mechanism having an actuating member coupleable to the pressure generating device, the actuating member being linearly adjustable by the motor to actuate the pressure generating device in a first direction against the restoring force; the control device is electrically connected with the motor and is used for controlling the motor; a switch which can be activated by the transmission mechanism as a result of the movement of the braking element in the second direction; and an electric brake circuit which is electrically connected to the motor and to the switch and which can be activated by activation of the switch and an electric activation voltage, the motor generating an activation voltage by absorbing a restoring force acting on the actuating member as a generator in the event of a failure of the control device, and the brake circuit being designed to brake the motor, in this way, a force counteracting the restoring force is generated by means of the motor.

Description

Technical Field

[0001] The invention relates to an electromechanical brake actuator, a drive assembly for an electromechanical brake actuator and a method for operating an electromechanical brake actuator. Background Art

[0002] Electromechanical brake boosters are usually used to boost the actuation force generated manually at the brake pedal by actuating the master brake cylinder with the aid of an electric motor. Actuators are also used in so-called "brake-by-wire" systems, in which an actuating signal is generated by actuating the brake pedal or in some other way, and an electrohydraulic actuator is actuated based on the actuating signal to generate brake pressure, which actuator is constructed in a similar manner to an electrohydraulic brake booster.

[0003] DE 10 2013 213 888 B3 discloses an electromechanical actuator for a brake system having a master brake cylinder, an electric motor and a transmission which couples the electric motor to the master brake cylinder in order to convert a movement of the motor into an actuation of the master brake cylinder.

[0004] If the control of the electric motor fails in an actuator constructed in this way, for example due to a power failure, the transmission is loaded with a restoring force by the built-up hydraulic pressure, wherein the electric motor actuates the master brake cylinder or a pressure generating device in general. The transmission is actuated by the restoring force and causes the electric motor to rotate, so that the electric motor operates as a generator. Since an uncontrolled pressure reduction can lead to an uncontrolled actuation of the transmission, the electric motor is usually braked via an electronic braking circuit to avoid damage to components, especially to the transmission. Of course, it is also desirable to reduce the pressure as quickly as possible in the event of a motor failure, so that effective compensation measures can be taken quickly to generate the necessary brake pressure. Summary of the invention

[0005] Against this background, the invention provides a drive assembly for an electromechanical brake actuator having the features of claim 1 , an electromechanical brake actuator having the features of claim 8 , and a method having the features of claim 10 .

[0006] According to a first aspect of the present invention, a drive assembly for an electromechanical brake actuator comprises: an electric motor; a transmission mechanism kinematically coupled to the motor, the transmission mechanism having an actuating member that can be coupled to a pressure generating device, the actuating member being capable of being linearly adjusted by the motor to overcome a reset force and cause the pressure generating device to actuate in a first direction; a control device electrically connected to the motor and used to control the motor; a switch that can be activated by the transmission mechanism due to movement of the actuating member in a second direction; and an electric brake circuit that is electrically connected to the motor and the switch and can be activated by activation of the switch and an electrical activation voltage, wherein the motor generates an activation voltage by absorbing the reset force acting on the actuating member as a generator when the control device fails, and wherein the brake circuit is designed to brake the motor so as to generate a force that counteracts the reset force with the aid of the motor.

[0007] According to a second aspect of the present invention, an electromechanical brake actuator is provided, which has a drive assembly according to the first aspect of the present invention and a pressure generating device, the pressure generating device is coupled to an actuating member of a transmission mechanism and has a hydraulic interface for providing hydraulic fluid to a wheel brake. The pressure generating device is designed to generate hydraulic pressure by pushing the hydraulic fluid.

[0008] According to a third aspect of the invention, a method for operating an electromechanical brake actuator according to the second aspect of the invention is provided. The method comprises: controlling a motor by a control device so that the motor moves an actuating member in a first direction or a second direction so as to build up or reduce a hydraulic pressure by means of a pressure generating device. In the event of a failure of the control device, for example due to a supply voltage failure or due to an error in the control device itself, the actuating member of the transmission mechanism moves in the second direction due to the reset force generated by the built-up hydraulic pressure. The actuating member moving in the second direction drives the motor as a generator so that the motor generates an activation voltage, and due to the movement of the actuating member in the second direction, the switch is activated through the transmission mechanism. In another step, the brake circuit is activated when the activation voltage is supplied to the brake circuit and the switch is activated. Then, the brake circuit brakes the motor so that the motor generates a force that reacts to the reset force, which slows down the movement of the actuating member in the second direction.

[0009] The invention is based on the idea that in the event of a control failure, a passive electronic braking circuit that brakes the electric motor in the event of a control failure is not activated immediately, but only under the additional condition that a linearly moving backward component of the transmission triggers an activation switch, which in turn activates the braking circuit. This allows the transmission to first run freely or unbraked over a certain distance by means of the hydraulic pressure acting backward as a restoring force by the pressure generating device before the transmission is braked by the motor braked by means of the braking circuit. In particular, the pressure generating device can thereby first perform a pressure reduction without braking, thereby advantageously reducing the time for the pressure reduction.

[0010] Advantageous embodiments and developments emerge from the further dependent claims and from the description with reference to the drawings.

[0011] According to some embodiments, it can be provided that the motor has a control circuit, such as a bridge circuit, which can be switched by a control device to operate the motor, and the brake circuit is designed to switch the control circuit to brake the motor. For example, the brake circuit can switch the control circuit so that the poles and / or individual phases of the motor are short-circuited via the control circuit, so that at least part of the rotor winding and / or stator winding of the motor forms an eddy current brake.

[0012] According to some embodiments, it is proposed that the brake circuit is designed to detect a failure of the control device, in particular based on a failure signal output by the control device, and is activated only when a failure of the control device is detected. For example, the control device can be designed to output a signal, for example in the form of a voltage, to the brake circuit during normal operation. If the signal is missing when the control device fails, the brake circuit detects that there is a failure of the control device. For detection, the brake circuit can have, for example, a normally closed switch. If the signal of the control device is missing, the switch is closed.

[0013] According to some embodiments, it can be proposed that the actuating member can be moved between an initial position and an actuation end position, wherein the reset force preloads the actuating member in the direction of the initial position, and wherein the switch is arranged so that the switch is activated in the activation position of the actuating member, in which the actuating member is closer to its initial position than to its actuation end position. In order to build up pressure, the actuating member can be displaced in a first direction by a pressure generating device, i.e., starting from its initial position and moving toward the actuation end position. In order to reduce pressure, the actuating member can be moved in a second direction, i.e., moving in the direction of the initial position. The switch is positioned relative to the transmission mechanism so that the switch is triggered when the pressure is reduced only when the actuating member is closer to its initial position than the actuation end position. Therefore, the transmission mechanism is free to rotate at least 50% of the maximum stroke that can be implemented by the actuating member. In this way, the pressure reduction is further accelerated.

[0014] In general, it can be provided that the initial position and the actuation end position define the maximum travel of the actuation member, and wherein the distance of the activation position from the initial position lies in the range between 5% and 40% of the maximum travel. Thus, the activation switch is activated or actuated shortly before the actuation member reaches its initial position. In this way, the pressure reduction is further accelerated.

[0015] According to some embodiments, it can be proposed that the switch is designed as a proximity switch, in particular a reed switch or a Hall switch. For example, the transmission mechanism can be provided with a proximity element, such as a magnet sheet, and the proximity sensor is positioned relative to the transmission mechanism so that when the actuating member moves in the second direction, the proximity element approaches the proximity sensor, thereby outputting a signal to the brake circuit.

[0016] According to some embodiments, it is proposed that the switch is designed as a mechanically triggerable switch. Here, the switch can be preloaded to an open state by a spring or the like, for example, and closed by an element of a transmission mechanism, whereby the switch closes an electrical switch in the brake circuit.

[0017] According to some embodiments, it is proposed that the actuating member is formed by a threaded spindle, which is linearly guided by a guide part connected to the threaded spindle in a rotationally fixed manner and can be linearly adjusted by a drive nut that can be rotated by a motor, wherein the switch can be triggered by the guide part. This offers the advantage that the guide part is already used as a carrier structure for the sensor element, which particularly simplifies the integration of the proximity switch into the drive assembly.

[0018] According to some embodiments, the motor can be designed as a brushless DC motor, which has a permanent magnet rotor, a stator, and at least three coil devices, and a commutation circuit connected to the coil devices, the commutation circuit can be controlled by a control device, and the brake circuit is designed to short-circuit at least two coil devices so that the at least two coil devices act as eddy current brakes. Therefore, the commutation circuit forms the control circuit of the motor and can be implemented as a B6 bridge circuit, for example.

[0019] According to some embodiments, it is proposed that the pressure generating device has a cylinder and a piston accommodated in the cylinder, the piston can be moved in the forward direction and the rearward direction by an actuating mechanism to displace the hydraulic fluid, wherein the hydraulic interface is formed by an interface hole in the cylinder, and wherein the cylinder has a sniffer hole, when the piston moves in the rearward direction, the sniffer hole is exposed by the piston in order to connect the cylinder to the reserve. Therefore, the pressure generating device can be, for example, a master brake cylinder or a plunger. By providing an activation switch for activating the brake circuit, in order to reduce the pressure, the piston can be moved in the rearward direction over a relatively large range with only a small reaction force, wherein the reaction force substantially corresponds to the friction force in the transmission mechanism and the motor. Therefore, a faster opening of the sniffer hole is achieved. This simplifies the rapid compensation of failures in the pressure generation, because a replacement system (for example an ABS system) may require hydraulic fluid from the reserve. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is explained below with reference to the accompanying drawings, wherein:

[0021] Figure 1 A schematic cross-sectional view showing an electromechanical brake actuator according to one embodiment of the present invention;

[0022] Figure 2 A schematic functional circuit diagram of a drive assembly according to an embodiment of the present invention is shown, wherein a transmission mechanism of the drive assembly is not shown;

[0023] Figure 3 A flow chart showing a method according to one embodiment of the present invention;

[0024] Figure 4 A diagram showing the movement speed of a piston of a brake actuator plotted over a movement path.

[0025] In the figures, unless otherwise indicated, the same reference signs denote identical or functionally identical components. DETAILED DESCRIPTION

[0026] Figure 1 An electromechanical brake actuator 300 is shown by way of example and purely schematically. Figure 1 As shown in , the brake actuator 300 comprises a drive assembly 100 having an electric motor 1 , a transmission 2 , a control device 3 , an activation switch 4 , an electric brake circuit 5 and a pressure generating device 200 .

[0027] The pressure generating device 200 is generally designed to generate hydraulic pressure and can be actuated by the drive assembly 100. Figure 1, the pressure generating device 200 can have, for example, a cylinder 210, a piston 212, and an optional reservoir 220. The cylinder 210 has an interface 211, for example in the form of a hole, which can be designed in particular in the first end region of the cylinder 210. The pressure generating device 200 can be connected to one or more wheel brakes (not shown) via the interface 211. In addition, the cylinder 200, in particular in the second end region, has a sniffer hole 213, through which the cylinder 210 is connected to the reservoir 220 via a pipeline. The piston 212 can move axially in the cylinder 210 in the forward direction Y1 and in the rearward direction Y2, and as shown in FIG. Figure 1 As shown in the example, the return spring 214 can be used to preload in the backward direction Y2.

[0028] In order to build up hydraulic pressure, the piston 212 can be moved in the forward direction Y1 by the drive assembly 100. This reduces the internal volume of the cylinder 210 and sprays hydraulic fluid through the interface 211. Figure 1 As schematically shown, once the piston 212 has moved far enough in the forward direction Y1, the piston 212 closes the sniffer hole 213. To reduce the pressure, the piston 212 can be moved in the rearward direction Y2 by the drive assembly 100. Once the piston 212 is positioned behind the sniffer hole 213 relative to the rearward direction Y2, the piston exposes the sniffer hole, allowing the hydraulic fluid from the reservoir 220 to enter the cylinder 210.

[0029] As already mentioned, the drive assembly 100 is designed to drive or actuate the pressure generating device 200 .

[0030] The electric motor 1 generally has a rotor 11 and a stator 12, and is kinematically coupled to the transmission 2, in particular the rotor 11. Figure 2 The motor 1 is shown here purely by way of example, which is designed as a brushless DC motor and has a permanent-magnet rotor 11 and a stator 12 with three coil arrangements 121, 122, 123. Each coil arrangement 121, 122, 123 forms a phase interface. Figure 2 The motor 1 shown by way of example in FIG. 1 also has a control circuit 13 which serves in particular as a commutation circuit and which can be designed as a bridge circuit, for example. Figure 2 2 , it is shown by way of example that the control circuit 13 is designed as a B6 bridge circuit having electronic switching elements (eg transistors) V1 - V6 .

[0031] The control device 3 is electrically connected to the control circuit 13 or generally to the motor 1, and is designed to control the motor 1, in particular to control the operation of the motor 1. For example, the control device 3 can have a computing unit (not shown), in particular a computing unit in the form of an ASIC (abbreviation of "Application-specific Integrated Circuit" in English), and a storage unit in the form of an SD memory, for example. The control device 3 is particularly designed to output a control signal. For example, the control device 3 can output a control signal to the control circuit 13 to switch the switching elements V1-V6 so that the coil devices 121, 122, 123 of the stator 12 generate a rotating magnetic field that drives the rotor 11.

[0032] like Figure 1 and Figure 2 It is also shown that the control device is optionally also connected to the brake circuit 5 in a signal-conducting or electrically manner, as will be explained further below.

[0033] Reference again Figure 1 , it can be seen that the transmission mechanism 2 kinematically couples the motor 1 to the piston 212 or generally to the pressure generating device 200. The transmission mechanism 2 has, in particular, an actuating member 20, which can be moved axially or linearly in a first direction X1 and a second direction X2 by the motor 2. The actuating member 20 can be, for example, a threaded spindle. In addition, the transmission mechanism 2 can have a guide component 21, which is connected to the threaded spindle in a rotationally fixed manner and can be guided displaceably in the first direction X1 and the second direction X2, for example in a housing 7 accommodating the transmission mechanism 2. Therefore, the threaded spindle is linearly guided by the guide component 21. In order to axially displace the threaded spindle, a drive nut 22 can be provided, which has an internal thread that engages in the external thread of the threaded spindle. The drive nut 22 can be rotated by the motor 1, for example, via a spur gear 23 coupled to the drive shaft 10 of the motor 1, the spur gear meshing with the external toothing of the drive nut 22, as shown in Figure 1 It is shown purely by way of example. Obviously, other torque transmission paths between the motor 1 and the actuating member 20 are also conceivable.

[0034] like Figure 1 , the actuating member 20 is coupled to the pressure generating device 200, in particular to the piston 212. The displacement of the actuating member 20 in the first direction X1 actuates the pressure generating device 200 to build up pressure, for example by the actuating member 20 displacing the piston 212 in the forward direction Y1. The displacement of the actuating member 20 in the second direction X2 brakes the pressure generating device 200 to reduce pressure, for example by the actuating member 20 displacing the piston 212 in the direction Y2.

[0035] Typically, the actuation member is displaceable between an initial position and an actuation end position. In order to build up pressure, the actuation member 20 is displaced in a first direction X1 from the initial position towards the actuation end position.

[0036] like Figure 1 It can be seen that when the pressure generating device 200 is actuated to build up pressure, a reset force F acts on the piston 212 in the rearward direction Y, which is applied by the spring 214, in particular by the hydraulic fluid. If the motor 1 no longer generates torque, for example in the event of failure of the control device 3, the reset force F causes the actuating member 20 to move in the second direction X2. The distance traveled by the actuating member 20 between the initial position and the actuation end position corresponds to the maximum stroke h20 of the actuating member 20. Figure 1 For example, a position Z2 corresponding to the position of the guide part 21 in the actuation end position of the actuation member 20 and a position Z1 corresponding to the position of the guide part 21 in the initial position of the actuation member 20 are depicted in FIG.

[0037] The activation switch 4 can be designed, for example, as a mechanically actuable switch or as Figure 1 As schematically shown in FIG. 1 , it is designed as a proximity switch, such as a reed switch or a Hall switch. Figure 1 As shown schematically, the switch 4 can be attached to the housing 7, for example. For example, the approach component 41 in the form of a magnet can be arranged at the guide component 21, for example, so that when the approach component 41 drops below a preset distance relative to the switch 4, in particular when the guide component 21 moves along the second direction X2 with the brake member 20, the switch 4 is activated. Obviously, the switch 4 can also be arranged at the housing guide component 41 and the approach component 41 is arranged at the housing 7. Alternatively, the approach component 41 or the switch 4 can also be attached to the actuating member 20. Therefore, preferably, the movement of the guide component 21 along the second direction X1 can trigger the switch 4. This also applies in the case of a mechanical switch. Generally, the switch 4 can be activated by the transmission mechanism 2 due to the movement of the actuating member 20 along the second direction X2. If the switch 4 is activated or generally switched by the transmission mechanism 2, the switching process in the brake circuit 5 is triggered by the switch 4, for example, by the switch 4 outputting a signal to the brake circuit 5.

[0038] exist Figure 1In the example in , the switch 4 can be arranged, for example, at a distance s20 away from the position Z1 in the first direction, wherein the distance s20 is optionally in a range between 5% and 40% of the maximum stroke h20. Therefore, the guide member passes between 60% and 95% of the maximum stroke h20 along the second direction X2 from the actuation end position when moving until the guide member activates the switch 4. The position of the actuating member 20 that activates the switch 4 can be referred to as the activation position. Therefore, the activation position can be in a range between 5% and 40% of the maximum stroke h20 at a distance s20 from the initial position. Generally, the switch 4 can be arranged so that the actuating member 20 is closer to its initial position in the activation position than its actuation end position.

[0039] Braking circuit 5 Figure 1 and Figure 2 4 is only shown symbolically as a block and is electrically connected to the motor 1 and the switch 4. Optionally, a brake circuit 5 can also be electrically connected to the control device 3. The brake circuit 5 is implemented as a passive circuit and is designed to brake the motor 1 in the event of a failure of the control device 3. For example, the brake circuit 5 can be designed to Figure 2 At least two of the three coil arrangements 121, 122, 123 shown in FIG. 1 are short-circuited so that the coil arrangements form an eddy current brake that brakes the rotating rotor 11. To this end, the brake circuit 5 can, for example, close at least two of the three switches V2, V4, V6.

[0040] The brake circuit 5 is designed such that it is activated when it receives the activation voltage and additionally activates the switch 4. Optionally, the brake circuit 5 can also be designed to detect a failure of the control device 3, in particular based on a failure signal output by the control device 3, and is activated only when a failure of the control device 3 is detected. The activation voltage is generated by the motor 1, because when the brake mechanism 20 is moved in the second direction X2 by the reset force F when the control device 3 fails, the rotor 11 of the motor is rotated, and the motor 1 forms a generator.

[0041] The electromechanical actuating member 300 can be operated according to method M, the process of which is as follows: Figure 3 It is schematically shown in FIG.

[0042] In step M1, the motor 1 is controlled by the control device 3 so that the motor 1 moves the actuating member 20 in the first X1 or second direction X2 so as to build up and reduce the hydraulic pressure by means of the pressure generating device 200. For example, the control device 3 outputs a control signal to the control circuit 13 of the motor 1 to switch the switching element 13.

[0043] In step M11, the brake circuit 5 detects whether there is a failure of the control device 3. If no failure is detected, such as in Figure 3If a failure of the control device 3 is detected, such as in Figure 3 As indicated by the symbol “+”, the method transitions to executing steps M2 to M5.

[0044] In step M2, the actuating member 20 is moved in the second direction X2 by a restoring force F, which acts on the actuating member 20 due to the hydraulic pressure via the piston 212 or generally via the pressure generating device 200. In step M3, by moving the actuating member 20 in the second direction X2, the motor 1 is driven as a generator via the transmission mechanism 2 and an activation voltage is thereby generated, which is applied to the brake circuit 5.

[0045] In step M4, the switch 4 is activated by the transmission mechanism 2 due to the movement of the actuating member 20 along the second direction X2. In particular, when the actuating member 20 reaches the activation position, that is, Figure 1 For example, when the guide member 21 moves along the second direction X2 and reaches the switch 4, the switch 4 is actuated.

[0046] In step M41, the brake control device 5 detects whether the activation voltage is generated and whether the switch 4 is activated. Since the brake control device 5 is designed as a passive circuit, the detection step M41 may include, for example, actuating the first switch element of the brake control device by the activation voltage and actuating the second switch element by the switch signal generated by the switch 4. If one of the two preconditions does not exist in step M41 ( Figure 3 The symbol "-" in the method M can return to step M2, such as Figure 3 When the activation voltage and the activation of the switch are detected, as shown in FIG. Figure 3 The “+” symbol indicates that the brake circuit 5 is activated in step M5 .

[0047] In step M6 (which can also be regarded as a sub-step of step M5), the brake circuit 6 brakes the motor 1 in the following manner, for example: Figure 2 As shown by way of example, at least two of the three coil arrangements 121, 122, 123 are short-circuited. The motor 1 is thereby braked and generates a force that counteracts the restoring force and slows down the movement of the actuating member 20 in the second direction X2.

[0048] The present invention is particularly useful in Figure 4 becomes obvious, Figure 4 A diagram is shown in which the path covered by the piston 212 or the brake member 20 is plotted on the abscissa A1 and the speed at which the piston 212 or the brake member 20 is moved is plotted on the ordinate.

[0049] exist Figure 4In the embodiment, the actuating member 20 is in the position Pm of its actuation end position, and in the position Pm, the control device 3 is ineffective. As a result, the piston 212 or the actuating member 20 is accelerated substantially linearly due to the hydraulic reset force F. The velocity Vg (in Figure 4 From position Pg in the figure, the motor 1 starts to act as a generator and generates an activation voltage for supplying the brake circuit 5. If the brake circuit 5 is activated at this time point, another speed trend will be obtained, such as Figure 4 As can be seen from the course of line L1, the motor 1 is immediately braked by the brake circuit 5 in this case, and the speed of the actuating member 20 or the piston 212 is slowly and substantially linearly reduced to the final speed Ve until the actuating member 20 reaches its initial position.

[0050] In the method according to the invention or due to the structure of the actuating member 300 with the switch 4 according to the invention, it is obtained Figure 4 . Thus, the motor 1 also acts as a generator from the position Pg of the actuating member 20 and generates an activation voltage for supplying the brake circuit 5. However, the brake circuit 5 is not yet activated, and the speed of the piston 212 or the actuating member 20 continues to increase, for example substantially linearly, until the actuating member 20 reaches the activation position Pa. At the activation position Pa, the switch 4 is activated and thereby the brake circuit 5 is activated, which then brakes the motor 1. Thus, starting from the activation position Pa, the speed decreases again until the initial position is reached and again until the final speed Ve.

[0051] exist Figure 4 In the example of , the time required for the actuating member 20 and thus the piston 212 to perform the maximum stroke h20 is inversely proportional to the area under the corresponding trends L1 and L2. Therefore, it can be seen that the speed trend L2 obtained by the present invention causes a significant reduction in the time required to perform the maximum stroke h20 to reduce the pressure.

[0052] Although the present invention has been exemplarily explained above based on the embodiments, the present invention is not limited thereto but can be modified in various ways. In particular, combinations of the above embodiments are also conceivable.

Claims

1. A drive assembly (100) for an electromechanical brake actuator (300), comprising: Electric motor (1); a transmission mechanism (2) kinematically coupled to the motor (1), the transmission mechanism having an actuating member (20) capable of being coupled to a pressure generating device (200), the actuating member being capable of being linearly adjusted by the motor (1) to overcome a reset force and actuate the pressure generating device (200) along a first direction (X1); A control device (3) electrically connected to the motor (1) and used to control the motor (1); a switch (4) which can be activated by the transmission mechanism (2) due to the movement of the actuating member (20) in the second direction (X2); and an electric braking circuit (5), which is electrically connected to the motor (1) and the switch (4) and can be activated by activation of the switch (4) and an electric activation voltage, The motor (1) generates the activation voltage by absorbing the restoring force acting on the actuating member (20) when the control device (3) fails, and the braking circuit (5) is designed to brake the motor (1) so as to generate a force that counteracts the restoring force by means of the motor (1).

2. A drive component (100) according to claim 1, wherein the braking circuit (5) is also designed to detect failure of the control device (3), in particular based on a failure signal output by the control device (3), and is only activated when failure of the control device (3) is detected.

3. A drive assembly (100) according to claim 1 or 2, wherein the actuating member (20) is capable of moving between an initial position and an actuating end position, wherein the reset force preloads the actuating member (20) in the direction of the initial position, and wherein the switch (4) is arranged so that the switch is activated in an activation position of the actuating member (20), in which activation position the actuating member (20) is closer to its initial position than to its actuating end position.

4. A drive assembly (100) according to claim 3, wherein the initial position and the actuation end position define a maximum stroke (h20) of the actuation member (20), and wherein a distance (s20) of the activation position from the initial position is within a range between 5% and 40% of the maximum stroke (h20).

5. The drive assembly (100) according to any one of the preceding claims, wherein the switch (4) is designed as a proximity switch, in particular a reed switch or a Hall switch, or a mechanically triggerable switch.

6. A drive assembly (100) according to any one of the preceding claims, wherein the actuating member (20) is formed by a threaded spindle, the threaded spindle is linearly guided by a guide component (21) that is non-rotatably connected to the threaded spindle, and can be linearly adjusted by a drive nut (22) that can be rotated by the motor (1), wherein the switch (4) can be triggered by the guide component (21).

7. The drive assembly (100) according to any one of the preceding claims, wherein the motor (1) is designed as a brushless DC motor, the brushless DC motor having: a permanent magnet rotor (11); a stator (12), the stator having at least three coil arrangements (121, 122, 123); and a commutation circuit (13) connected to the coil arrangements (121, 122, 123), the commutation circuit being controllable by the control device (3), and The brake circuit (5) is designed to short-circuit at least two coil arrangements (121, 122, 123), so that the at least two coil arrangements act as eddy current brakes.

8. An electromechanical brake actuator (300), comprising: A drive assembly (100) according to any one of the preceding claims; and A pressure generating device (200) is coupled to the actuating member (20) of the transmission (2) and has a hydraulic connection (202) for supplying hydraulic fluid to wheel brakes.

9. The brake actuator (300) according to claim 8, wherein the pressure generating device (200) has a cylinder (210) and a piston (212) accommodated in the cylinder (210), the piston being movable in a forward direction (Y1) and a rearward direction (Y2) by the actuating mechanism (20) to displace the hydraulic fluid, wherein the hydraulic interface (202) is formed by an interface hole (211) in the cylinder (210), and wherein the cylinder (210) has a sniffer hole (213), and when the piston (212) moves in the rearward direction (Y2), the sniffer hole is exposed by the piston so as to connect the cylinder (210) to a reservoir (220).

10. A method (M) for operating an electromechanical brake actuator (300) according to claim 8 or 9, comprising: controlling (M1) the motor (1) by means of the control device (3) so that the motor (1) moves the actuating member (20) in the first direction (X1) or the second direction (X2) so as to build up or reduce hydraulic pressure by means of the pressure generating device (200); Wherein, in the event of failure of the control device (3): Due to the restoring force generated by the built-up hydraulic pressure, the actuating member (20) moves (M2) in the second direction (X2), The actuating member (20) moving in the second direction (X2) drives the motor (1) as a generator, so that the motor (5) generates (M3) an activation voltage; Due to the movement of the actuating member (20) along the second direction (X2), the switch (4) is activated (M4) via the transmission mechanism (2); When the activation voltage is supplied to the brake circuit (5) and the switch (4) is activated, the brake circuit (5) is activated (M5); and The braking circuit (6) brakes the motor (1), so that the motor (1) generates a force that reacts against the reset force, and the force slows down the movement of the actuating member (20) along the second direction (X2).

Images