Position sensor of a valve actuator for an internal combustion engine

• US 20050231194A1
• Filed: 04/06/2005
• Published: 10/20/2005
• Est. Priority Date: 04/06/2004
• Status: Active Grant

• Current Assignee: Peugeot Citroen Automobile SA (Stellantis NV)
• Original Assignee: Peugeot Citroen Automobile SA (Stellantis NV)
• Inventors: Baldi, Christophe, Lalu, Daniel
• Granted Patent: US 7,188,592 B2
• Time in Patent Office: Days
• US Class Current: 324/207.180
• CPC Class Codes: G01D 5/2291 Linear or rotary variable differential transformers (LVDTs/RVDTs) having a single primary coil and two secondary coils

Abstract

A sensor of the position of a target is secured to an electromagnetic or electromechanical valve actuator of an internal combustion engine. The target is driven by a reciprocating translatory motion (f₊, f₋) in synchronism with that of the valve. The sensor uses an eddy current transducer, including two secondary coils connected in series opposition and a primary coil fed by a radio frequency current. The output signal of the transducer is sent to a phase locked loop synchronous detector. The coils are engraved or printed on a flexible film. The transducer is arranged in an external tube made of aluminum and includes an internal wall made of insulating material.

Claims

1. A position sensor of a first device secured to an electromagnetic or electromechanical valve actuator, intended for an internal combustion engine, the first device being driven by a reciprocating translatory motion along a fixed direction in synchronism with motion of the valve, the position sensor comprising:

a target, made of electrically conductive material, secured to the first device, so as to follow the reciprocating translatory motions,

a transducer comprising;

a first winding fed by a alternating current of fixed frequency,

second and third windings connected according to a series opposition configuration by a first common end, and electromagnetically coupled to one another, the primary winding inducing eddy currents in the target and being electromagnetically coupled to the second and third windings,

a fixed substrate for the first to third windings, the first to third windings being arranged in such a way that an output voltage generated by the transducer, which is proportional to a difference between voltages induced by the eddy currents in the second and third windings, respectively, develops, by electromagnetic induction, between the second ends of the second and third windings, and,

a conditioner circuit, receiving, on a first input channel, the output voltage and, on a second input channel, a reference alternating electric signal with a frequency substantially identical to the fixed frequency, the conditioner circuit comprising a synchronous demodulation circuit, so as to generate, at an output terminal, a electric signal representative of an instantaneous position of the target along the fixed direction.

2. A sensor in accordance with claim 1, wherein the conditioner circuit is offset in relation to the transducer, the conditioner circuit being placed in a location substantially protected from thermal gradients and from physicochemical corrosions.

3. A sensor in accordance with claim 1, wherein the first, second and third windings are arranged symmetrically in relation to an axis linked with the substrate.

4. A sensor in accordance with claim 1, wherein the valve actuator comprises a plate arranged between two solenoids, a high solenoid EA_H and a low EA_S solenoid, the plate being attached to a rod for driving a valve, and wherein the first device to which the target is secured is composed of the plate or the driving rod.

5. A sensor in accordance with claim 1, wherein the valve is extended by a valve stem device, the target is attached to the valve stem device, the first device and the target communicates the reciprocating translatory motion to the first device.

6. A sensor in accordance with claim 1, wherein the fixed frequency is in the radio frequency range.

7. A sensor in accordance with claim 1, wherein the target is a metal rod comprising at least one tooth arranged along the fixed direction.

8. Sensor in accordance with claim 7, wherein the electrically conductive material of the target is aluminum.

9. A sensor in accordance with claim 1, wherein the first to third windings are composed of flat coils, engraved or printed on a flexible substrate.

10. A sensor in accordance with claim 9, wherein the flexible substrate is made of polyimide.

11. A sensor in accordance with claim 9, wherein the primary winding comprises a plurality of turns coiled around said secondary windings connected in series opposition.

12. A sensor in accordance with claim 1, wherein the synchronous demodulation circuit of the conditioner circuit comprises a phase locked loop.

13. A sensor in accordance with claim 1, wherein the actuator comprises a frame, the transducer and the target are arranged in an opening of this frame, which opening is closed by a plug for adjusting a rate of a spring and for positioning the sensor in relation to the target, the transducer being arranged coaxially to the target inside a tube forming an external wall.

14. A sensor in accordance with claim 13, wherein the tube is made of a material offering protection against electromagnetic fields.

15. A sensor in accordance with claim 13, wherein the transducer comprises a internal wall made of an electrically insulating material.

16. A sensor in accordance with claim 1, wherein the conditioner circuit is at a distance from the transducer and from the target, and wherein the conductor circuit receives the output voltage generated by the transducer by means of jumpers, so as to create a telemetry system.

17. A sensor in accordance with claim 16, wherein, with the motor comprising a plurality of said valves and valve actuators, each of the valves being associated with a transducer, the sensor includes a plurality of said conditioner circuits receiving the output voltages generated by the transducers the plurality of conditioner circuits being arranged in a single integrated circuit.