INDUCTIVE SENSOR ASSEMBLY FOR DETECTING A CHANGE IN POSITION OF AN ACTUATING ELEMENT

Abstract

An inductive sensor assembly is used for detecting a change in position of an actuating element. The sensor assembly has: an LC resonant circuit having an inductive element (L) and a capacitive element (C); an excitation supply which is coupled to the LC resonant circuit in order to excite the LC resonant circuit with an excitation voltage (U); a decoupling element arranged between the excitation supply and the LC resonant circuit; and, an evaluation arrangement for evaluating the signal decreasing across the resonant circuit. An actuating assembly is also provided.

Claims

1. An inductive sensor assembly for detecting a change in position of an actuating element, wherein the inductive sensor assembly comprises: an LC resonant circuit having an inductive element and a capacitive element, an excitation supply which is coupled to the LC resonant circuit in order to excite the LC resonant circuit with an excitation voltage, a decoupling element arranged between the excitation supply and the LC resonant circuit, and, an evaluation assembly for evaluating the signal decreasing across the resonant circuit.

2. An inductive sensor assembly according to claim 1, wherein the excitation supply is set up to output the excitation voltage at an operating frequency that corresponds to the natural frequency of the resonant circuit or is tuned to it.

3. An inductive sensor assembly according to claim 1, wherein the evaluation assembly has a rectifier circuit.

4. An inductive sensor assembly according to claim 3, wherein the rectifier circuit has a diode and a capacitance which is preferably connected in parallel with the resonant circuit.

5. An inductive sensor assembly according to claim 3, wherein the rectifier circuit is arranged between the LC resonant circuit and an ADC of the evaluation assembly, wherein the evaluation assembly is set up to detect a voltage value rectified at the rectifier with the ADC and to detect a change in position as present depending on the detected voltage value.

6. An inductive sensor assembly according to claim 5, wherein the evaluation assembly is set up to detect a change in position as present if an upper threshold voltage value is exceeded or if a lower threshold voltage value is undershot.

7. An inductive sensor assembly according to claim 1, wherein the evaluation assembly does not have a rectifier circuit, and an ADC of the evaluation assembly detects a voltage decreasing across the resonant circuit, wherein an inertia of the ADC is adapted to an operating frequency of the excitation supply in such a way that a minimum measurement duration of the ADC lasts at least one period of the resonant circuit excitation, preferably between 5 and 1000 periods of the resonant circuit excitation, particularly preferably between 5 and 100 periods of the resonant circuit excitation, more preferably between 5 and 20 periods of the resonant circuit excitation.

8. An actuating assembly, in particular on a motor vehicle, comprising an inductive sensor assembly according to claim 1, and a metallic actuating element, wherein the metallic actuating element carries out a change in position relative to the inductive element when actuated.

9. An inductive sensor assembly according to claim 4, wherein the rectifier circuit is arranged between the LC resonant circuit and an ADC of the evaluation assembly, wherein the evaluation assembly is set up to detect a voltage value rectified at the rectifier with the ADC and to detect a change in position as present depending on the detected voltage value.

10. An inductive sensor assembly according to claim 2, wherein the evaluation assembly does not have a rectifier circuit, and an ADC of the evaluation assembly detects a voltage decreasing across the resonant circuit, wherein an inertia of the ADC is adapted to an operating frequency of the excitation supply in such a way that a minimum measurement duration of the ADC lasts at least one period of the resonant circuit excitation, preferably between 5 and 1000 periods of the resonant circuit excitation, particularly preferably between 5 and 100 periods of the resonant circuit excitation, more preferably between 5 and 20 periods of the resonant circuit excitation.

11. An actuating assembly, in particular on a motor vehicle, comprising an inductive sensor assembly according to claim 2, and a metallic actuating element, wherein the metallic actuating element carries out a change in position relative to the inductive element when actuated.

12. An actuating assembly, in particular on a motor vehicle, comprising an inductive sensor assembly according to claim 3, and a metallic actuating element, wherein the metallic actuating element carries out a change in position relative to the inductive element when actuated.

13. An actuating assembly, in particular on a motor vehicle, comprising an inductive sensor assembly according to claim 4, and a metallic actuating element, wherein the metallic actuating element carries out a change in position relative to the inductive element when actuated.

14. An actuating assembly, in particular on a motor vehicle, comprising an inductive sensor assembly according to claim 5, and a metallic actuating element, wherein the metallic actuating element carries out a change in position relative to the inductive element when actuated.

15. An actuating assembly, in particular on a motor vehicle, comprising an inductive sensor assembly according to claim 6, and a metallic actuating element, wherein the metallic actuating element carries out a change in position relative to the inductive element when actuated.

16. An actuating assembly, in particular on a motor vehicle, comprising an inductive sensor assembly according to claim 7, and a metallic actuating element, wherein the metallic actuating element carries out a change in position relative to the inductive element when actuated.

Description

[0036] FIG. 1a and 1b: schematic sketches of an actuating assembly 1;

[0037] FIG. 2: schematic circuit diagram of an inductive sensor assembly;

[0038] FIG. 1a is a schematic cross-sectional view of an actuating assembly 1 of a motor vehicle. In the embodiment shown by way of example, the actuating assembly 1 is a knob of a door handle, which knob is shown in cross section. Inside the knob 1, an inductive sensor assembly 2 is shown, which sensor assembly is arranged in its entirety on a circuit board in the embodiment shown. The inductive sensor assembly has a resonant circuit having a coil L. A metallic actuating element 4 designed as a metal foil is arranged on the casing portion of the door handle and on the inside of the door handle. The metallic actuating element 4 is arranged opposite the coil L of the inductive sensor assembly 2. Due to the resilient behavior of the casing portion of the door handle, the metallic actuating element 4 can be moved relative to the sensor assembly 2.

[0039] FIG. 1b shows how an effect on the casing portion is brought about as a result of the exertion of force (symbolized by the arrow 3 shown). As a result of the application of force, the metallic actuating element 4, which is designed as a metal foil, has carried out a change in position. The change in position is a consequence of a sectional change in location of the actuating element 4 in relation to the sensor assembly 2 as a result of the deformation of the actuating element 4. The change in location of the actuating element also occurred in particular relative to the coil L of the sensor assembly 2. The sensor assembly 2 serves the purpose of detecting the actuation that manifests itself in the deformation of the actuating element 4.

[0040] FIG. 2 shows an embodiment of an inductive sensor assembly according to the invention. The sensor assembly has an LC resonant circuit 5 which has the inductive element L and the capacitive element C. The inductive element represents the component of the sensor assembly which provides the functionality for detecting the change in position of a metallic and/or ferromagnetic actuating element. In the embodiment shown, the resonant circuit 5 is a parallel resonant circuit which is coupled to the excitation supply 6 via the decoupling resistor 7. The excitation supply 6 is a pin controller, the output pin of which provides the excitation signal for the resonant circuit 5. In the representation shown, the decoupling resistor has a resistance value of 5 kOhm. The evaluation assembly for evaluating the signal decreasing across the resonant circuit is made up of the rectifier 8, the capacitance C.sub.D (also referred to as C_D), which together form the rectifier circuit; together with the ADC 10 and resistor 9 and capacitance C.sub.G, which are used for signal smoothing but are not absolutely necessary for the actual functionality.