Inductively interrogated passive sensor apparatus

Patent metadata

Field	Value
Publication number	US-9506994-B2
Application number	US-63959210-A
Country	US
Kind code	B2
Filing date	Apr 6, 2010
Priority date	Apr 6, 2010
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

A sensor apparatus comprises a first magnetic transducer which in use is positioned on a first side of a barrier and a second magnetic transducer which in use is positioned on a second side of the barrier opposite the first side. The second transducer comprises a magnetic or electrical property which is dependent upon a sensible condition on the second side of the barrier, such as the pressure or temperature on the second side of the barrier. In operation, the first transducer generates a first magnetic field which induces the second transducer to generate a second magnetic field that is dependent upon the magnetic or electrical property of the second transducer. The first transducer detects the second magnetic field and generates a signal which is representative of the sensible condition on the second side of the barrier.

First claim

What is claimed is:

1. A sensor apparatus which comprises:
a first magnetic transducer which in use is positioned on a first side of a barrier, the first transducer being configured to generate a first purely magnetic field; and
a second magnetic transducer which in use is positioned on a second side of the barrier opposite the first side, the second transducer comprising a magnetic or electrical property which is dependent upon a sensible condition on the second side of the barrier and a sensor coil which is configured to generate a second purely magnetic field;
wherein in operation of the sensor apparatus the first transducer generates the first magnetic field, which induces the sensor coil to generate the second magnetic field, the second magnetic field being dependent upon the magnetic or electrical property of the second transducer; and
wherein the first transducer detects the second magnetic field and in response thereto generates a signal which is representative of the sensible condition on the second side of the barrier.

2. The sensor apparatus of claim 1 , wherein the first transducer comprises at least one transmitter coil for generating the first magnetic field and at least one receiver coil for detecting the second magnetic field.

3. The sensor apparatus of claim 2 , wherein the first transducer comprises two transmitter coils for generating the first magnetic field.

4. The sensor apparatus of claim 3 , wherein each of the transmitter coils and the receiver coils comprises a toroid.

5. The sensor apparatus of claim 3 , wherein the transmitter coils are positioned coaxially and in parallel planes and the receiver coil is positioned parallel to the transmitter coils.

6. The sensor apparatus of claim 5 , wherein the receiver coil is positioned between the transmitter coils a distance sufficient to substantially null out the first magnetic field at the receiver coil.

7. The sensor apparatus of claim 5 , wherein the receiver coil is positioned between the transmitter coils a distance sufficient to at least partially null out at the receiver coil a reflected magnetic field generated by eddy currents in the barrier.

8. The sensor apparatus of claim 2 , further comprising a nulling transducer for generating a third magnetic field which is sufficient to at least partially null out at the receiver coil a reflected magnetic field generated by eddy currents in the barrier.

9. The sensor apparatus of claim 8 , wherein the nulling transducer comprises a coil which is wound around a generally C-shaped core.

10. The sensor apparatus of claim 9 , wherein the C-shaped core is positioned around a segment of the receiver coil.

11. The sensor apparatus of claim 8 , wherein the nulling transducer comprises a coil which is wound around a toroidal core.

12. The sensor apparatus of claim 11 , wherein the toroidal core is positioned around a segment of the receiver coil.

13. The sensor apparatus of claim 2 , wherein at least one of the transmitter coil and the receiver coil further comprises a disc-shaped core which is positioned concentrically therein and is made of a high permeability material.

14. The sensor apparatus of claim 1 , wherein the first transducer comprises at least one transmitter coil for generating the first magnetic field, a first receiver coil for detecting both the second magnetic field and a reflected magnetic field generated by eddy currents in the barrier, and a second receiver coil for detecting primarily the reflected magnetic field.

15. The sensor apparatus of claim 14 , wherein the first transducer comprises two transmitter coils for generating the first magnetic field.

16. The sensor apparatus of claim 15 , wherein the transmitter coils are positioned coaxially and in parallel planes and the receiver coils are positioned parallel to the transmitter coils.

17. The sensor apparatus of claim 16 , wherein the first receiver coil is positioned partially between the transmitter coils on one side of the transmitter coils and the second receiver coil is positioned partially between the transmitter coils on the diametrically opposite side of the transmitter coils.

18. The sensor apparatus of claim 17 , wherein the sensor coil is positioned opposite the area of overlap between the transmitter coils and the first receiver coil.

19. The sensor apparatus of claim 14 , wherein the first receiver coil generates a first signal, the second receiver coil generates a second signal and the sensor apparatus further comprises means for combining the first and second signals to produce the signal which is representative of the sensible condition on the second side of the barrier.

20. The sensor apparatus of claim 1 , wherein the barrier comprises a conductive barrier and the first transducer is positioned against the conductive barrier.

21. The sensor apparatus of claim 1 , wherein the barrier comprises a conductive barrier and the second transducer is positioned against the conductive barrier.

22. The sensor apparatus of claim 1 , wherein the second transducer comprises a passive sensor device having an electrical property which is dependent upon the sensible condition on the second side of the barrier.

23. The sensor apparatus of claim 22 , wherein the sensor coil comprises a coil of conductive wire which is coupled to the sensor device.

24. The sensor apparatus of claim 23 , wherein the sensor device is electrically connected between the ends of the wire.

25. The sensor apparatus of claim 23 , wherein the second transducer further comprises a magnetically permeable core around which the wire is wound.

26. The sensor apparatus of claim 25 , wherein the core comprises a relative magnetic permeability of greater than about 1000.

27. The sensor apparatus of claim 1 , wherein the sensor coil comprises a coil of conductive wire whose ends are connected together.

28. The sensor apparatus of claim 27 , wherein the second transducer further comprises a magnetically permeable core around which the wire is wound.

29. A sensor apparatus which comprises:
a first magnetic transducer which in use is positioned on a first side of a conductive barrier the first transducer being configured to generate a first magnetic field which is capable of passing through the barrier; and
a second magnetic transducer which in use is positioned on a second side of the barrier opposite the first side, the second transducer comprising a magnetic or electrical property which is dependent upon a sensible condition on the second side of the barrier and being configured to generate a second magnetic field which is capable of passing through the barrier;
wherein in operation of the sensor apparatus the first transducer generates the first magnetic field, which induces the second transducer to generate the second magnetic field, the second magnetic field being dependent upon the magnetic or electrical property of the second transducer; and
wherein the first transducer detects the second magnetic field and in response thereto generates a signal which is representative of the sensible condition on the second side of the barrier.

30. The sensor apparatus of claim 29 , wherein the first transducer comprises at least one transmitter coil for generating the first magnetic field and at least one receiver coil for detecting the second magnetic field.

31

Assignees

• Mulholland John J
• Jaskolski Corey
• Borke Frank
• Silva Gabriel
• Bartlett Christopher D
• Fmc Tech Inc

Inventors

• Mulholland John J
• Jaskolski Corey
• Borke Frank
• Silva Gabriel
• Bartlett Christopher D

Classifications

• G01R33/02

  Measuring direction or magnitude of magnetic fields or magnetic flux (G01R33/20 takes precedence) · CPC title

• G01D5/204 Primary

  by influencing the mutual induction between two or more coils (G01D5/22 takes precedence) · CPC title

• G01R33/0005 Primary

  Geometrical arrangement of magnetic sensor elements; Apparatus combining different magnetic sensor types (G01R33/0206 takes precedence) · CPC title

• G01R33/0017

  Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields · CPC title