Method and device for determining the absolute position of a component of an actuator rotating about a rotational axis, in particular a clutch actuator

Abstract

The invention relates to a method for determining the absolute position of a component of an actuator rotating about a rotational axis, in particular a clutch actuator, wherein the component has a co-rotating magnetic element (18), and the absolute position of the magnetic element (18) is detected by way of a multi-turn sensor (16) located opposite the magnetic element (18), which is supplied with a voltage. In a method, in which the absolute position can be detected without great constructional effort, a position of the magnetic element (18) is monitored by a Wiegand wire unit (19), which detects a movement of the component when the actuator (3, 12, 13) is turned off, and if a movement is detected, transmits a voltage pulse to the multi-turn sensor (16) for measuring the current position of the component.

Claims

1. A method for determining an absolute position of a component of an actuator rotating about a rotational axis, wherein the component comprises a rotating magnetic element, the method comprising: providing a multi-turn sensor opposite to the rotating magnetic element configured to determine the absolute position of the magnetic element; supplying a voltage to the multi-turn sensor; monitoring a position of the magnetic element, by a Wiegand wire unit, which detects a movement of the component when the actuator is switched off; supplying the multi-turn sensor with voltage by a battery when the actuator is switched off and the multi-turn sensor is in a standby state; in the event of detected motion, transferring a voltage pulse from the Wiegand wire unit directly to the multi-turn sensor for measuring a current position of the component; and changing the multi-turn sensor from the standby state to an operating state after receiving the voltage pulse transmitted from the Wiegand wire unit.

2. The method as claimed in claim 1, further comprising the multi-turn sensor measuring and storing the current position of the component and then returning to the standby state.

3. The method as claimed in claim 1, further comprising triggering the voltage pulse by the Wiegand wire unit when the position of the magnetic element has changed by at least 180.

4. The method as claimed in claim 1, further comprising that when the actuator is switched on, supplying the multi-turn sensor with voltage by a supply voltage of a control unit and determining at least one of an angle of the component or rotations of the component by the multi-turn sensor.

5. A device for determining an absolute position of a component rotating about a rotational axis of an actuator, the device comprising: a multi-turn sensor configured to determine the absolute position of the component which comprises a magnetic element that follows a rotational movement of the component; a Wiegand wire unit configured to monitor the position of the magnetic element, the Wiegand wire unit is connected to a wake-up connection of sensor electronics of the multi-turn sensor in a standby state and is adapted to change the multi-turn sensor to an operating state by transferring a voltage pulse directly to the multi-turn sensor; and a battery configured to supply the multi-turn sensor with voltage when the actuator is switched off and the multi-turn sensor is in the standby state.

6. The device as claimed in claim 5, wherein when in the operating state the multi-turn sensor is connected to a supply voltage of a control unit.

7. The method of claim 1, wherein the actuator is a clutch actuator.

8. The device of claim 5, wherein the actuator is a clutch actuator.

9. A method for determining an absolute position of a rotating component of an actuator that rotates about a rotational axis, the method comprising: providing a magnetic element on the rotating component; providing a multi-turn sensor opposite to the magnetic element, the multi-turn sensor being configured to determine the absolute position of the magnetic element supplying a voltage to the multi-turn sensor via a battery when the actuator is switched off and the multi-turn sensor is in a standby state; monitoring a position of the magnetic element, using a Wiegand wire unit, which detects a movement of the component when the actuator is switched off; upon detecting a motion, the Wiegand wire unit transferring a voltage pulse to a wake-up connection of the multi-turn sensor for measuring a current position of the component; and changing the multi-turn sensor from the standby state to an operating state after receiving the voltage pulse transmitted from the Wiegand wire unit.

10. The method of claim 9, further comprising the multi-turn sensor measuring and storing the current position of the component and then returning to the standby state.

11. The method of claim 9, further comprising triggering the voltage pulse by the Wiegand wire unit when the position of the magnetic element has changed by at least 180.

12. The method of claim 9, further comprising the Wiegand wire unit switching on the actuator, supplying the multi-turn sensor with voltage by a supply voltage of a control unit, and determining at least one of an angle of the component or rotations of the component using the multi-turn sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure allows numerous embodiments. One of these will be explained in more detail on the basis of the figures shown in the drawing.

(2) In the figures:

(3) FIG. 1: shows a basic representation of a clutch actuation system for actuating an automated friction clutch,

(4) FIG. 2: shows an exemplary embodiment of the device according to the disclosure.

DETAILED DESCRIPTION

(5) In FIG. 1 a clutch actuation system 1 for an automated clutch is shown in a simplified form. The clutch actuation system 1 is associated with a friction clutch 2 in a power train of a motor vehicle and comprises a master cylinder 3 that is connected to a slave cylinder 5 via a hydraulic line that is referred to as a pressure line 4. In the slave cylinder 5, a slave piston 6 that can be moved reciprocally operates the friction clutch 2 via an operation element 7 with the interposition of a bearing 8.

(6) The master cylinder 3 can be connected via a connection opening to a compensating container 9. In the master cylinder 3, a master piston is 10 axially movably mounted. A piston rod 11 of the master cylinder 3 is connected by a threaded spindle 12 to an electromotive actuating drive 13. The electromotive actuating drive 13 comprises an electric motor embodied as a commutated electric motor 14 and a control unit 15. The threaded spindle 12 converts a rotational movement of the electric motor 14 into a longitudinal movement of the master piston 10 of the master cylinder 3. The friction clutch 2 is thus automatically operated by the electric motor 14, the threaded spindle 12, the master cylinder 3 and the slave cylinder 5.

(7) Since the electric motor 14 is an electrically commutated DC motor, it is necessary to know its absolute position for the position control of the electric motor 14. This absolute position is detected by a multi-turn sensor 16. When in the normal operating state, the multi-turn sensor 16 is connected to the control unit 15 and is supplied by the supply voltage of the control unit. The multi-turn sensor 16 is part of a chip 17, as is shown in FIG. 2. The chip 17 is arranged so that the multi-turn sensor 16 is opposite the rotor of the electric motor 14. In FIG. 2, for the sake of clarity a magnetic element 18 of the electric motor 14 is shown, which is firmly attached to an end face of the rotor of the electric motor 14 and which follows the rotational movement thereof. The magnetic element 18 is monitored by an opposite Wiegand wire unit 19 that is connected via a line 20 to a wake-up connection 21 of the chip 17 of the multi-turn sensor 16. In addition, the chip 17 of the multi-turn sensor 16 is coupled to the battery voltage U.sub.Batt.

(8) In normal operation of the actuator 3, 12, 13, the chip 17 is connected to the supply voltage of the control unit 15 and determines the angle of the magnetic element 18 and counts the rotations of the magnetic element in the process. Said rotations are necessary to adjust the commutation of the electric motor 14 correctly.

(9) However, if the actuator 3, 12, 13 is switched off, then the supply voltage supplying the control unit 15 and the multi-turn sensor 16 is also switched off.

(10) In this case, the multi-turn sensor 16 is in a standby state, which is maintained by the battery voltage U.sub.Batt. In this switched-off state of the actuator 3, 12, 13 it can happen that the position of the rotor of the electric motor 14 changes passively. In this case, the change in the angle of the magnetic element 18 is detected by the Wiegand wire unit 19. Said Wiegand wire unit 19 is a sensor that comprises Wiegand wires as an essential component that comprise a hysteresis curve with pronounced steps as a result of parallel soft and hard magnetic areas, which is known as the Wiegand effect. The sudden change in the magnetization caused by the change in position of the magnetic element 18 of the rotor of the electric motor 14 causes a voltage pulse in a coil near the wires. This voltage pulse is forwarded via the line 20 to the chip 17, whereby the multi-turn sensor 16 is awakened. The voltage pulse from the Wiegand wire unit 19 is triggered at the latest after a change in the position of 180 of the magnetic element 18 if the magnetic element 18 contains two-pole magnets. By means of the voltage pulse, the multi-turn sensor 16 changes from the standby state to the normal operating state thereof. In said normal operating state, the new position of the magnetic element 18 is measured and stored. Then the multi-turn sensor 16 is returned to the standby state.

REFERENCE LIST

(11) 1 Clutch actuation system 2 Friction clutch 3 Master cylinder 4 Hydraulic line 5 Slave cylinder 6 Slave piston 7 Actuating element 8 Bearing 9 Compensation container 10 Master piston 11 Piston rod 12 Threaded spindle 13 Actuation drive 14 Electric motor 15 Control unit 16 Multiturn sensor 17 Chip 18 Magnetic element 19 Wiegand wire unit 20 Line 21 Wake-up connection