Electric machine brake and lock device of the same and lock device control method

Abstract

To provide an electric machine brake and a lock device of the electric machine brake as well as a lock device control method.SOLUTION: A lock device includes: a ratchet gear 201 and a ratchet wheel 202 coaxially fixed and connected to each other; a pivotable ratchet component 23 which restricts rotation of the ratchet wheel 202 in a first direction and is released by rotation of the ratchet wheel 202 in a second direction when the ratchet component 23 and the ratchet wheel are interlocked; a spring member 24 which is connected to the ratchet component 23 so as to pivot the ratchet component 23 to an idle position; and an electromagnetic actuator 22 which acts on the ratchet component 23 to cause the ratchet component 23 to pivot from the idle position to an operation position against an elastic force of the spring member when operated at first polarity.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to the field of vehicle braking systems, and more particularly to an electromechanical brake, a locking device control method, and a locking device for an electromechanical brake. [Background technology]

[0002] Electromechanical brakes are devices that realize braking by driving brake calipers through a motor. Compared with traditional hydraulic pipeline brakes, electromechanical brakes feature fast response, simple structure, and easy maintenance. With the electrified and intelligent development of vehicles, electromechanical brakes are becoming a more popular braking system due to easier integration with the electrical control system.

[0003] In conventional hydraulic brake systems, hydraulic pressure in the brake cylinder is maintained by a hand or foot brake to achieve a parking brake. In contrast, electromechanical brakes often include a parking lock device to achieve the parking brake function, for example, by interfering with the transmission mechanism to lock the brake using a pin driven by an electromagnetic actuator. However, such systems require the electromagnetic actuator to remain energized when the vehicle is parked, and the parking brake may fail when the electromagnetic actuator fails. Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure aims to solve or at least alleviate the problems present in the prior art. [Means for solving the problem]

[0005] In one aspect, there is provided a locking device for an electro-mechanical brake, the locking device comprising: a ratchet gear and a ratchet wheel fixedly connected to each other on the same axis; a pivotable pawl component pivotable between an operating position engaged with the ratchet wheel and an idle position disengaged from the ratchet wheel, the pivotable pawl component restricting rotation of the ratchet wheel in a first direction and rotation of the ratchet wheel in a second direction releasing the pawl component when the pawl component and the ratchet wheel are engaged; a spring member coupled to the pawl component for biasing the pawl component to rotate toward the idle position; and an electromagnetic actuator that, when operated in a first polarity, acts on the pawl component to rotate the pawl component from an idle position to an operating position against the elastic force of the spring member.

[0006] In another aspect, an electro-mechanical brake is provided, the electro-mechanical brake comprising: A brake motor; a transmission device connected to the brake motor; A locking device according to each embodiment of the present disclosure, wherein a ratchet gear of the locking device engages with a transmission gear of a transmission device; A brake actuator coupled to the transmission device for receiving a brake torque and for performing a braking action.

[0007] In another aspect, a control method for a locking device is provided, the method comprising: controlling the brake motor to rotate in a forward direction to establish a predetermined braking torque when a parking brake signal is received; controlling the electromagnetic actuator to act on the pawl component to pivot the pawl component from an idle position disengaged from the ratchet wheel to an operative position; and controlling reverse rotation of the brake motor to move the pawl component into an operative position in engagement with the ratchet wheel and to stop the electromagnetic actuator and the brake motor.

[0008] Apparatus and methods according to embodiments of the present disclosure provide for parking brake operation of an electromechanical brake via a ratchet pawl mechanism without the need for an electromagnetic actuator to remain operational for extended periods of time, but only for a short period of time when operating conditions change.

[0009] The present disclosure will be more readily understood with reference to the accompanying drawings. Those skilled in the art will readily appreciate that the drawings are for illustrative purposes only and are not intended to represent limitations on the scope of the present disclosure. Moreover, like numerals in the drawings are used to indicate like components. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is an exploded view of an electromechanical brake assembled to a wheel hub according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is an exploded view of a portion of an electromechanical brake other than a brake actuator according to an embodiment of the present disclosure. [Diagram 3] FIG. 3 is an assembly diagram of an electromechanical brake locking device and transmission device according to an embodiment of the present disclosure. [Figure 4] FIG. 4 shows the internal structure of an electromechanical brake according to an embodiment of the present disclosure from different angles. [Diagram 5] FIG. 5 shows the internal structure of an electromechanical brake according to an embodiment of the present disclosure from different angles. [Figure 6] FIG. 6 is a cross-sectional view of a brake actuator of an electromechanical brake according to an embodiment of the present disclosure. [Figure 7] FIG. 7 is a perspective view of a locking device in an idle state of an electromechanical brake according to an embodiment of the present disclosure. [Figure 8] FIG. 8 is an exploded view of a locking device of an electromechanical brake according to an embodiment of the present disclosure. [Figure 9] FIG. 9 is a perspective view of a locking device in an idle state of an electromechanical brake according to an embodiment of the present disclosure from a different angle. [Figure 10] FIG. 10 is a perspective view of a locking device in an idle state of an electromechanical brake according to an embodiment of the present disclosure from a different angle. [Figure 11] FIG. 11 is a perspective view of a locking device in an operating state of an electromechanical brake according to an embodiment of the present disclosure. [Figure 12] FIG. 12 is a schematic diagram of a control structure for an electromechanical brake according to an embodiment of the present disclosure. [Figure 13] FIG. 13 is a schematic diagram of a control structure for an electromechanical brake according to an embodiment of the present disclosure. [Figure 14] FIG. 14 is a schematic diagram of a control structure for an electromechanical brake according to an embodiment of the present disclosure. [Figure 15] FIG. 15 is a schematic diagram of a control structure for an electromechanical brake according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1 shows an exploded perspective view of an electro-mechanical brake 100 according to an embodiment of the present disclosure having a rotating shaft 91, a shock absorber 92, a bearing 94, a knuckle arm 93, a brake disc 95, and a wheel 96. The electro-mechanical brake 100 is driven by a motor that provides braking force by clamping the brake disc 95 with a brake caliper. The electro-mechanical brake 100 is mounted on the knuckle arm 93 during assembly. The electro-mechanical brake 100 is further accommodated in a compact space within the hub of the wheel 96.

[0012] The electromechanical brake 100 according to the embodiment of the present disclosure includes a brake motor 13, a transmission device 14 coupled to the brake motor 13, a locking device 2, and a brake actuator 3 (FIG. 6). With reference to FIGS. 2-5, the electromechanical brake 100 is introduced, except for the brake actuator 3. The brake motor 13 provides a brake torque, and its output shaft is connected to a pinion 131. Furthermore, a first sensor 132 is connected to the output shaft of the brake motor 13 to sense the state of the brake motor 13, such as speed and stage. The brake motor 13 passes through the first housing 12 and the internal space surrounded by the first housing 12 and the second housing 11, in which the transmission device 14 and the locking device 2 are disposed, and the transmission device 14 connects between the brake motor 13 and the brake actuator 3 to transmit the rotation torque of the brake motor 13 to the brake actuator 3, reducing the speed and increasing the torque. The locking device 2 provides a parking brake to prevent a state such as slipping during parking. More specifically, a pinion 131 on the output shaft of the brake motor 13 engages with a hub gear 142 through an intermediate gear 141, which outputs torque through a planetary gear set and by a planet carrier 144 of the planetary gear set. The planet carrier 144 has a profiled shaft bore 145 that is coupled to the input shaft 31 of the brake actuator 3 of FIG. 6 to transmit torque to the brake actuator 3. In another embodiment, the locking device 2 comprises a ratchet assembly 20 comprising a ratchet gear 201 and a ratchet wheel 202 fixedly connected coaxially, the ratchet gear 201 also engaging with the hub gear 142. Referring to FIG. 3, the transmission device 14 and the locking device 2 are generally herringbone shaped and therefore housed in a herringbone shaped housing. It will be appreciated that although a particular configuration of the transmission device is shown in the drawings, other configurations of the transmission device may also be used in alternative embodiments.Additionally, although the locking device 2 and hub gear 142 of the transmission engage as shown in the drawings, in alternative embodiments the locking device 2 may engage with any of the gears on the main drive chain of the transmission or engage with the transmission via other gears.

[0013] 6, a cross-sectional view of the brake actuator 3 is shown. As described above, the input shaft 31 of the brake actuator 3 is connected to the shaft hole 145 of the planetary carrier 144 of the transmission device 14 for receiving torque, the input shaft 31 is connected to or integrally formed with the lead screw 32, and the rotational torque of the input shaft 31 is converted into an axial displacement of the nut 33 by the connection of the lead screw 32 and the nut 33 in the ball screw device. The nut 33 then axially pushes the plunger 34 to drive a pair of friction plates 35 on the floating brake actuator 3 to grip a brake disc 95 (not shown) therebetween, thereby generating a braking force by bringing the friction plates 35 into contact with the brake disc 95.

[0014] Next, the specific configuration of the locking device 2 according to the embodiment of the present invention will be described in conjunction with FIGS. 7 to 11. The locking device 2 according to the embodiment of the present disclosure includes a ratchet gear 201 and a ratchet wheel 202 that are coaxially fixed and connected, both of which have a coaxial rotation axis and are fixed and connected to rotate together. A ratchet assembly 20 composed of the ratchet gear 201 and the ratchet wheel 202 is supported by a pair of bearings 203. A rotatable detent component 23 that can pivot between an operating position (shown in FIG. 11) that is interlocked with the ratchet wheel 202 and an idle position (shown in FIG. 10) that is separated from the ratchet wheel 202. When the detent component 23 is interlocked with the gear 202, the detent component 23 prevents the ratchet wheel 202 from rotating in a first direction (clockwise in FIG. 11), and the rotation of the ratchet gear 201 in a second direction (counterclockwise in FIG. 11) releases the detent component. A detent component 23, a spring member 24 that biases the detent component 23 to rotate toward the idle position, and an electromagnetic actuator 22 that acts on the detent component 23 when energized to rotate the detent component 23 from the idle position to the operating position. When the ratchet gear 201 of the ratchet assembly 20 engages with the hub gear 142 of the transmission device 14, the rotation of the ratchet gear 201 and the ratchet wheel 202 in the first direction corresponds to the reverse rotation of the brake motor 13 and the transmission device 14, that is, the rotation in the direction of releasing the brake torque. On the other hand, the rotation of the ratchet gear 201 and the ratchet wheel 202 in the second direction corresponds to the forward rotation of the brake motor 13 and the transmission device 14, that is, the rotation in the direction of increasing the brake torque. Therefore, the detent component 23 in the operating position prevents the ratchet wheel 202 from rotating in the first direction, thereby preventing the reverse rotation of the brake motor 13 and the transmission device 14 from releasing the brake torque, maintaining the brake torque, and achieving the parking brake.

[0015] In some embodiments of the present disclosure, the locking device 2 comprises a base 21 to which the pawl component 23 is pivotally fixed by a pivot 28 and to which the electromagnetic actuator 22 is also fixed. In some embodiments of the present disclosure, the base 21 is formed by bending a metal material and comprises a first plane 211 and a second plane 212 perpendicular to each other. The electromagnetic actuator 22 is mounted in an opening on the first plane 211 of the base. Furthermore, an additional opening 210 is provided on the first plane 211 of the base for mounting the spring member 24, while a mounting hole 213 is provided on the second plane 212 of the base 21 for receiving the pivot 28. Furthermore, a plurality of bolt holes are provided on the second plane 212 of the base 21 for fixing the base 21 and its components through bolts 214.

[0016] In some embodiments of the present disclosure, the pawl component 23 includes a shaft bore 230 coupled to a pivot 28, with a pawl portion 231 protruding from the shaft bore 230 in a first direction to engage the ratchet wheel 202, a rocker arm 232, and a magnet 27 at an end of the rocker arm 232 extending from the shaft bore 230 in a second direction, and an electromagnetic actuator acts on the magnet 27 at the end of the rocker arm 232. More specifically, the pivot 28 passes through the shaft bore 230 of the pawl component 23 and through a washer 291 that is received by a mounting hole 213 on the second planar surface 212 of the base 21. The pivot 28 has a boss portion 281, with the pawl component 23 positioned between the boss portion 281 and the washer 291. In some embodiments of the present disclosure, a mounting hole 233 is provided at the end of the rocker arm 232 of the pawl component 23, and the magnet 27 is mounted in the mounting hole 233 by a pin 271. Once mounted in place, the magnet 27 is positioned above and adjacent the electromagnetic actuator 22 in an idle position.

[0017] In some embodiments of the present disclosure, the spring member 24 is a coil spring comprising a first end 241, a coiled portion 242, a second end 244, and a mounting hook 243 at an end of the second end 244. The first end 241 of the spring member 24 is mounted in an additional opening 210 on the first surface 211 of the base, the coiled portion 242 surrounds a boss portion 281 of the pivot 28 and is defined by a snap ring 29, and the second end 244 of the spring member 24 is secured at an end to the pawl component 23 by the mounting hook 243 such that the mounting hook 243 is attached to a pin 271 of the magnet 27 at an end of the rocker arm 232 of the pawl component 23. In some embodiments of the present disclosure, the spring member 24 is preloaded, i.e., in the idle state shown in Fig. 8, and when its second end 244 is released, the second end 244 rotates in the direction of the arrow R toward the first end 241, so that the spring member 24 in the idle position preloads the pawl component 23 to maintain it in the idle position. In some embodiments of the present disclosure, the locking device 2 further comprises a buffer 26 disposed at the end of the rocker arm, e.g., a rubber bushing designed to first contact the base when the pawl component 23 moves from the operating position to the idle position, thereby preventing or at least mitigating a collision of the magnet 27 at the end of the pawl component 23 with the electromagnetic actuator 22. In some embodiments of the present disclosure, the locking device 2 further comprises a position sensor 25 that detects the position of the pawl component 23, the position sensor 25 detecting the position of the pawl component 23 by sensing the magnetic field of a magnet 27 at the end of the rocker arm, for example, the position sensor 25 may be located on one side of the magnet 27 of the pawl component 23 in the operative position, such that the position sensor 25 senses an increase in the magnetic field of the magnet 27 when the pawl component 23 is in the operative position, thereby determining that the pawl component 23 is in the operative position and that the pawl component 23 returns to the idle position when the magnetic field decreases to an initial value near the idle position.

[0018] 12-15, modes of operation of an electromechanical brake according to an embodiment of the present disclosure under operating conditions such as parking brake and parking brake release are described. FIG. 12 shows a controller 4, such as a vehicle ECU, connected to a power source 251 of the position sensor 25 for controlling power supply to the position sensor 25 and receiving a feedback signal of the position sensor 25, the controller 4 being further coupled to a power source 221 of the electromagnetic actuator 22 to control power supply to the electromagnetic actuator 22. Additionally, the controller 4 is further connected to the brake motor 13 to control operation of the brake motor 13 and to a first sensor 132 on the output shaft 131 of the brake motor 13 to receive feedback regarding the state of the brake motor 13, and further, the controller 4 may also include an output torque sensor 139 of the electromechanical brake connected to a current sensor 138 to receive an actual output brake torque. Also shown are the pawl component 23 and magnet 27, the ratchet assembly 20, the hub gear 142, and the intermediate gear 141 thereon, which are connected as described above in connection with FIGS. 1-11.

[0019] During normal operation, the locking device 2 may be inoperative, its ratchet assembly 20 rotates with the hub gear 142, and the controller 4 controls the brake motor 13 to output a braking torque based on the displacement of the brake pedal. In this state, in some embodiments of the present disclosure, the power supply 251 of the position sensor 25 and the power supply 221 of the electromagnetic actuator 22 may be turned off.

[0020] 1-11 and 13, for example, after the electronic handbrake is pressed after the passenger has parked the vehicle, the controller 4 receives a parking brake signal P, which controls the brake motor 13 to rotate forward to establish a predetermined braking torque. Upon receiving a feedback signal from the output torque sensor 139 that the predetermined braking torque has been established, the controller 4 may activate the power supply 221 of the electromagnetic actuator 22 to provide power to the electromagnetic actuator 22 acting on the pawl component 23, and more specifically, to the magnet 27 thereon, which overcomes the retaining force of the spring member 24 to pivot the pawl component 23 from an idle position isolated from the ratchet wheel to an operating position. At this time, or any time after receiving the parking brake signal P, the controller 4 may control the power supply 251 of the position sensor 25 to provide power to the position sensor 25 to detect the position of the pawl component 23. The pawl component 23 may be pivoted to a position close to its operating position, as shown in FIG. 13. Thereafter, as shown in FIG. 14, the controller 4 controls the brake motor 13 to rotate in the reverse direction, so that the pawl component 23 engages with the ratchet wheel of the ratchet assembly 20, at which point the pawl component 23 reaches its operating position completely. Naturally, the angle of the reverse rotation of the motor 13 is less than one pitch of the corresponding ratchet wheel, but this reverse rotation results in a reduction in the brake torque. Therefore, this reverse rotation should be taken into account when setting the predetermined braking torque. For example, the predetermined brake torque may be at least the sum of the brake torque required for the parking brake and the torque corresponding to an additional rotation pitch of the ratchet wheel, or may be set to increase to a larger torque, for example, a torque corresponding to an additional two or more rotation pitches of the ratchet wheel, thereby avoiding a reduction in the parking brake torque due to the reverse rotation of the brake motor. Thereafter, for example, when the position sensor 25 detects that the pawl component 23 is in the operating position, the electromagnetic actuator 22 and the brake motor 13 can be stopped.Therefore, according to an embodiment of the present disclosure, the locking device 2 only needs to supply power to the electromagnetic actuator 22 for a short period of time when the parking brake is applied, avoiding long-term power supply to the electromagnetic actuator 22 during parking and avoiding failure of the parking brake caused by a defective electromagnetic actuator 22.

[0021] In some embodiments of the present disclosure, the controller 4 need only control the brake motor 13 to rotate forward when a parking brake signal is received, such that the rotation corresponds to, for example, the pitch of the pawl, which causes the ratchet assembly 20 to rotate in a direction opposite to that shown in Figure 14, thereby releasing the pawl component 23 and returning the pawl component to an idle position based on the operation of the spring member, after which the brake motor is then controlled to rotate in the reverse direction to release the braking force. In some embodiments of the present disclosure, the controller 4 may control the electromagnetic actuator 22 to act on the pawl component 23 to provide a buffer while the pawl component returns to the idle position based on the operation of the spring member, at which point the current of the electromagnetic actuator 22 can be controlled to be relatively small to reduce the force.

[0022] Additionally, the pawl component 23 may deviate from the idle position due to vibrations of the vehicle during operation. To avoid this situation, in some embodiments of the present disclosure, as shown in FIG 15, the controller 4 may be configured to control the electromagnetic actuator 22 to act on the pawl component 23 with a second polarity opposite to the first polarity to exert an attractive force on the magnet 27 on the pawl component 23, so that the pawl component 23 is maintained in the idle position when no parking brake signal is received and the pawl component 23 is detected to leave the idle position.

[0023] The above-described embodiments of the present disclosure are intended only to more clearly explain the principles of the present disclosure, and individual components are clearly shown or described to facilitate the understanding of the principles of the present disclosure. Various modifications or variations can be easily made to the present disclosure by those skilled in the art without departing from the scope of the present disclosure. Therefore, it should be understood that such modifications or variations are subject to the patent protection of the present disclosure.

Claims

1. A locking device for electromechanical brakes, A ratchet gear (201) and a ratchet wheel (202) are fixed and connected to the same axis, A swivelable stud component (23) capable of swiveling between an operating position linked to the ratchet wheel (202) and an idle position separated from the ratchet wheel (202), wherein the stud component (23) restricts the rotation of the ratchet wheel (202) in a first direction, and releases the stud component (23) when the rotation of the ratchet wheel (202) in a second direction is linked to the stud component (23) and the ratchet wheel (202), and A spring member (24) is connected to the aforementioned brake stop component (23) and biases the brake stop component (23) to rotate toward the idle position, A locking device comprising: an electromagnetic actuator (22) that acts on the locking component (23) such that, when operating in a first polarity, the locking component (23) rotates the locking component (23) from the idle position to the operating position with respect to the elastic force of the spring member (24).

2. The locking device according to claim 1, comprising a base (21) including a first plane (211) and a second plane (212), wherein the electromagnetic actuator (22) is fixed to the first plane (211) of the base, and the choke component (23) is rotatably fixed to the second plane (212) of the base by a pivot axis (28).

3. The aforementioned brake component (23) is A shaft hole (230) connected to the aforementioned pivot shaft (28), A stopper portion (231) extending in a first direction from the shaft hole (230), A rocker arm (232) extending in a second direction from the shaft hole (230), The magnet (27) at the end of the rocker arm, Equipped with, The locking device according to claim 2, characterized in that the magnet (27) is connected to the end of the rocker arm (232) by a pin (271), and the electromagnetic actuator (22) acts on the magnet (27) at the end of the rocker arm.

4. The locking device according to claim 3, further comprising a position sensor (25) for detecting the position of the locking component (23), wherein the position sensor (25) detects the position of the locking component (23) by sensing the magnetic field of the magnet (27) located at the end of the rocker arm.

5. The locking device according to claim 3, further comprising a buffer (26) disposed at the end of the rocker arm.

6. The spring member (24) is The first end (241) and Coiled portion (242) and The second end (244) and Equipped with, The first end (241) of the spring member (24) is attached to an additional opening (210) in the first plane (211) of the base of the locking device. The coiled portion (242) surrounds the pivot axis (28), The second end (244) of the spring member (24) is fixed to the end of the rocker arm (232) of the choke component (23), The locking device according to claim 3, characterized in that the spring member (24) is pre-pressed with an elastic force, and as a result, when the stabilizing component (23) is in the idle position, the spring member (24) exerts a force to hold the stabilizing component (23) in the idle position.

7. The locking device according to claim 1, further characterized in that the electromagnetic actuator (22) can operate in a second polarity to exert force on the stud component (23) to hold the stud component (23) in the idle position.

8. It is an electromechanical brake, Brake motor (13) and A transmission device (14) connected to the brake motor (13), The locking device (2) according to claim 1, wherein the ratchet gear (201) of the locking device is connected to the transmission device (14), and the locking device An electromechanical brake characterized by comprising: a brake actuator (3) connected to the transmission device to receive brake torque and perform braking operation.

9. The electric mechanical brake according to claim 8, wherein the brake motor (13) and the ratchet gear (201) of the locking device (2) are connected to the hub gear (142) of the transmission device, so that the rotation of the ratchet gear (201) and the ratchet wheel (202) in the first direction corresponds to the rotation in the reverse direction which releases the brake torque of the brake motor (13) and the transmission device (14), while the rotation of the ratchet gear (201) and the ratchet wheel (202) in the second direction corresponds to the rotation in the forward direction which establishes the brake torque of the brake motor (13) and the transmission device (14), and the hub gear (142) is connected to the input shaft (31) of the brake actuator (3) by the planetary carrier (144) of the planetary gear set.

10. A method for controlling an electromechanical brake according to claim 8 or 9, The steps include controlling the brake motor (13) to rotate it in the forward direction to establish a predetermined braking torque when a parking brake signal is received, The steps include controlling the electromagnetic actuator (22) to act on the wheel lock component (23) to rotate the wheel lock component (23) from an idle position separated from the ratchet wheel (202) to an operating position, The steps include controlling the rotation of the brake motor (13) in the reverse direction to move the chock component (23) to the operating position and to interlock it with the ratchet wheel (202), thereby stopping the electromagnetic actuator (22) and the brake motor (13), A control method characterized by having the following features.

11. The system further includes a position sensor (25) for detecting the position of the aforementioned brake stop component (23), The control method according to claim 10, further comprising detecting the position of the wheel stop component (23) by the position sensor (25) when the wheel stop component (23) is in the operating position, and stopping the electromagnetic actuator (22) and the brake motor (13).

12. The brake motor (13) is controlled to rotate in the forward direction, and upon receiving the parking brake signal, the wheel chock component (23) is released, and as a result, the wheel chock component (23) returns to the idle position based on the operation of the spring member (24). The control method according to claim 10, further comprising the step of controlling the rotation of the brake motor (13) in the reverse direction to release the braking torque when it is detected that the stopper component (23) has returned to the idle position.

13. The control method according to claim 12, further comprising controlling the electromagnetic actuator (22) to act on the choke component (23) with the first polarity, thereby providing a buffer when the choke component (23) rotates from the operating position to the idle position based on the operation of the spring member (24).

14. The control method according to claim 10, further comprising, when a parking brake signal is not received and it is detected that the wheel chock component (23) has moved away from the idle position, controlling the electromagnetic actuator (22) to act on the wheel chock component (23) with a second polarity opposite to the first polarity, thereby maintaining the wheel chock component (23) in the idle position.

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