Device and Method to Reduce Clutch Engagement Speed

Abstract

A safety device includes a safety module and a safety control module in order to reduce a speed of an unwanted clutch engagement when a malfunction of a motor for a clutch control actuator occurs, such as by the power supply for the motor being interrupted, so that a driver can have more time to react in such situation.

Claims

1.-17. (canceled)

18. A safety device for an electric motor which controls an actuator for a vehicle driveline clutch system, where the motor includes at least three coils, comprising: a safety module, including switches for each of the at least three coils of the motor, respectively; a safety control module configured to provide an output signal to the safety module, which actively holds the switches opened during a regular operation of the motor, and to provide an output signal to the safety module, which closes the switches when a malfunction of the motor is detected, so that the coils are shorted and the motor is stopped slower than in a normal power-off situation; and an energy storage device to be charged with a power supply during the regular operation, wherein the energy storage device is configured to power the safety control module, when a malfunction of the motor occurs, to send the output signal to the safety module to close the switches.

19. The safety device according to claim 18, wherein the safety device is configured so that when a malfunction of the motor occurs, the coils are connected with ground to be shorted.

20. The safety device according to claim 18, further comprising: resistors connected with each of the coils, wherein the resistors are configured so that their resistance can be adjusted, and/or the switches are configured so that their resistance can be adjusted.

21. The safety device according to claim 18, wherein the switches are FET or MOSFET switches.

22. The safety device according to claim 18, wherein the safety control module is configured to be connected with a failure control device to receive an input signal to detect whether a malfunction occurs to the motor.

23. The safety device according to claim 18, wherein the energy storage device is at least one of: (i) a capacitor, (ii) provided with a Zener-diode configured to set a maximal voltage charged in the energy storage device, and (iii) configured so that its energy storage capability is adjustable.

24. The safety device according to claim 18, wherein the safety control module is at least one of: (i) configured so that a stored energy in the energy storage device is configured to be completely used during an active braking operation by said safety device, (ii) configured so that the capability of the energy storage device is configured dependent on the power supply, and (iii) configured so that the energy storage device is ensured to operate at a minimum operational power supply level of the vehicle driveline clutch system with a safety margin.

25. The safety device according to claim 18, wherein the safety control module comprises switches SW1, SW2, SW3 and SW4 configured so that, SW1 and SW4 are closed and SW2 and SW3 are opened during regular operation of the motor, and SW1 and SW4 are opened and SW2 and SW3 are closed when a malfunction of the motor is detected.

26. The safety device according to claim 25, wherein the switch SW1 is configured to be triggered by a predetermined minimal voltage level.

27. The safety device according to claim 26, wherein the voltage level for triggering the switch SW1 is configured to be lower than a minimal operational power supply level of the vehicle driveline clutch system.

28. The safety device according to claim 25, wherein the switch SW4 is configured to keep the switches in the safety module opened during the regular operation of the motor.

29. A method for a vehicle driveline clutch system to slow down a clutch engagement speed, when a malfunction of a motor for a clutch control actuator occurs, where the motor comprises at least three coils and the motor is driven by a power supply in a regular operation, the method comprising the steps of: connecting each coil of the motor with a switch from a safety device; keeping the switches opened during a regular operation of the motor; closing the switches to short the coils when a malfunction of the motor occurs, using an energy from an energy storage device.

30. The method according to claim 29, wherein the coils are connected with ground to be shorted when a malfunction of the motor is detected.

31. The method according to claim 30, wherein at least one of: (i) resistance of the coils are adjusted by adjusting windings of the coils to adjust braking effect of the motor, (ii) resistors are provided and connected with the coils and resistance of the resistors is adjusted, (iii) resistance of the switches are adjusted, and (iv) an energy storage capability of the energy storage device is adjusted.

32. The method according to claim 29, wherein a failure control device is connected with the safety device providing an input signal to the safety device whether a malfunction is occurred to the motor.

33. The method according to claim 29, wherein a maximal voltage charged in the energy storage device is controlled.

34. The method according to claim 29, wherein the energy storage capability of the energy storage device is adjusted dependent on the power supply.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a schematic diagram of a motor, a motor driver, a safety module and a safety control module according to one embodiment of the present invention.

[0024] FIG. 2 is a schematic circuit design of the safety control module from FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 shows an electric motor 2 with three coils 20a, 20b and 20c, each connected with a resistor 22a, 22b and 22c, respectively. The coils 20a, 20b and 20c are mounted on a stator (not shown) of the motor, and a rotor (not shown) of the motor rotates to hold (drag) a clutch spring. A motor driver 1 is provided to control a regular operation of the motor 2, where the motor driver 1 is connected with a power supply 10. A safety module 3 is provided to be connected with the motor 2. The safety module 3 comprises switches 30a, 30b and 30c, which are configured to be connected with each of the coils 20a, 20b and 20c of the motor 2, respectively. A safety control module 4 is provided to be connected with the safety module 3 and controls the switches 30a, 30b and 30c.

[0026] FIG. 2 shows a detailed circuit design of the safety control module 4 according to a preferred embodiment of the present invention. The safety control module 4 is connected with a failure control device 5 to receive an input signal to decide whether a malfunction of the motor occurs.

[0027] During the regular operation, a power supply 10 is active and an energy storage device 42 is charged with the power supply 10. A Zener-diode 44 is provided to set a maximal voltage level to be charged in the energy storage device 42. Furthermore, the energy storage device 42 is configured to have a predetermined energy storage capacity C.

[0028] Four switches SW1, SW2, SW3 and SW4 are built in the safety control module 4. During the regular operation, the power supply 10 is active and controls SW4 so that SW4 is closed and sends a signal to the safety module 3 where the signal is used to keep the switches 30a, 30b and 30c in FIG. 3 open. At the same time, the switch SW1 is held closed, whereas the switches SW2 and SW3 are opened.

[0029] When a malfunction occurs, i.e. the power supply 10 is off, SW4 is triggered to be opened, and the failure control device 5 generates a signal to open the switch SW1. Where the trigger can be a predetermined minimal voltage level, for example, when the voltage is lower than the minimal operational power supply level of the vehicle driveline clutch system. Once the SW1 is opened, SW2 is triggered to be closed, followed by SW3 triggered to be closed. At this moment, the energy storage device 42 switches from a power-charging state to a power-supply state, which enables the safety control module 4 to send a signal to the safety module 3 to close the switches 30a, 30b and 30c, so that the coils 20a, 20b and 20c are shorted by being connected to ground 32.

[0030] The braking effect of the motor 2 can be adjusted by adjusting the windings of the coils 20a, 20b and 20c, and/or resistance of the resistor 22a, 22b and 22c of the motor 2 and/or resistance of the switches 30a, 30b and 30c of the safety module 3. Furthermore, the duration of the braking effect can be adjusted by the type of the switches 30a, 30b and 30c, a voltage level (Ubrake) and/or the energy storage capability C of the energy storage device 42 of the safety control module 4.

[0031] With the above brake device, the coils 20a, 20b and 20c are all shorted by connecting to the ground 32, when a malfunction function occurs and the power supply 10, 10 is off, which eliminates magnet fields generated by a resilience force from a clutch spring to the rotor of the motor 2, so that the release of the clutch spring is slowed down, meaning an unwanted engagement of the clutch is slowed down, providing a driver more time to react.