Method for operating an actuator arrangement for a clutch operating system, and actuator arrangement

Abstract

A method for operating an actuator arrangement for a clutch operating system includes providing an actuator arrangement with a transmission, a piston, and an inductive sensor device. The transmission has an electric motor and a metal lead screw that converts a rotary motion into a linear motion. The piston is connected to the metal lead screw. The method also includes energizing the electric motor to linearly displace the metal lead screw in an axial direction, axially displacing the piston with the metal lead screw, using the metal lead screw as a target for the inductive sensor device, and using the inductive sensor device to determine an axial distance traveled by the piston.

Claims

1. A method for operating an actuator arrangement for a clutch operating system comprising: providing an actuator arrangement comprising: a transmission comprising: an electric motor; and a metal lead screw that converts a rotary motion into a linear motion; a piston connected to the metal lead screw; and an inductive sensor device; energizing the electric motor to linearly displace the metal lead screw in an axial direction; axially displacing the piston with the metal lead screw; using the metal lead screw as a target for the inductive sensor device; and using the inductive sensor device to determine an axial distance traveled by the piston.

2. The method of claim 1, wherein the inductive sensor device comprises: a coil surrounding at least a portion of the metal lead screw; and an evaluation circuit.

3. The method of claim 2, wherein an excitation frequency of the coil is tuned with respect to a surrounding zone of influence of the coil within the actuator arrangement.

4. The method of claim 2, wherein the coil is linearized.

5. The method of claim 1 further comprising: providing a rotational position sensor; and checking plausibility of the axial distance by measuring a rotation of the metal lead screw with the rotational position sensor.

6. An actuator arrangement for a clutch operating system, comprising: a transmission comprising a metal lead screw that converts a rotary motion of the transmission into a linear motion; a piston connected to the metal lead screw; and a sensor device for determining a travel of the piston, comprising: a coil that surrounds the metal lead screw such that the metal lead screw is used as a sensor target; and an evaluation circuit, connected to the coil, for determining a metal lead screw position from a change in an inductance of the coil.

7. The actuator arrangement of claim 6, wherein the evaluation circuit is arranged within the actuator arrangement.

8. The actuator arrangement of claim 6 further comprising a metal shield arranged around the coil.

9. The actuator arrangement of claim 6, further comprising a coil carrier; wherein: the coil is arranged on the coil carrier; and an extent of the coil predetermines an entry zone for the metal lead screw.

10. The actuator arrangement of claim 6, further comprising a rotor position sensor for detecting a rotation of the metal lead screw that is arranged opposite one end of the metal lead screw.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure allows numerous embodiments. One of these will be explained in greater detail by means of the figures of the drawings. In the drawings:

(2) FIG. 1 shows an illustrative embodiment of the actuator arrangement according to the disclosure,

(3) FIG. 2 shows an equivalent circuit diagram for the inductance measurement, and

(4) FIG. 3 shows an actuator arrangement according to the prior art.

DETAILED DESCRIPTION

(5) FIG. 1 illustrates an example embodiment of actuator arrangement 1 according to the disclosure, which has a transmission 2 driven by an electric motor 3. The rotary motion of the transmission 2 is converted by a lead screw 4 into a linear motion, thereby moving a piston 5 axially. The lead screw 4 is made from a metal. At an opposite end from the piston 5, the lead screw 4 is surrounded by a coil 6, which is arranged on a carrier element 7. The coil 6 and the carrier element 7 are surrounded by a metal shield 8. An evaluation circuit 10, which is connected to the coil 6, is positioned on a carrier board 9.

(6) During the movement of the metal lead screw 3, which acts as a metal core of the coil 6, the inductance of the coil 6 changes. In order then to detect the position of the piston 5 with the aid of the lead screw 3, the lead screw 3 damps the coil 6 as it enters the entry path predetermined by the coil 6. The entry path of the lead screw 4 is thus proportional to the coil damping. This coil damping is measured by means of the evaluation circuit 10 since it results in different inductances of the coil. In this case, the evaluation circuit 10 deduces the position of the lead screw 4 and thus the distance traveled by the piston 5 from the inductance measurement. An equivalent circuit diagram is illustrated in FIG. 2.

(7) In order to compensate for nonlinear inductances, which are caused primarily by static metal components in the immediate zone of influence of the coil 6, the coil 6 is linearized. The metal shield 8 shields the coil 6 from external dynamic influences. Through the adaptation of an excitation frequency of the coil 6 to the immediate surroundings, the static metal tube of the metal shield 8 is thus also blanked out by an offset compensation in the output signal of the evaluation circuit 10.

(8) In one embodiment, a magnetic rotor position sensor (not illustrated specifically) is arranged at an opposite end of the lead screw 4 from the piston. This rotor position sensor is used to detect the axial position of the lead screw 4 when the actuator arrangement is switched on. This is necessary in order to cover a complete path of movement of the lead screw 4, which can amount to several motor revolutions. Over 3600, the position of the lead screw can be determined by the rotor position sensor for motor commutation. Thus, the axial distance which has been determined by inductance measurement can be calibrated by means of the rotation measurement of the rotor position sensor.

REFERENCE NUMERALS

(9) 1 actuator arrangement 2 mechanism 3 electric motor 4 lead screw 5 piston 6 coil 7 carrier element 8 metal shield 9 carrier board 10 evaluation electronics 11 magnet 12 displacement sensor