High sensitivity inductive sensor for measuring blade tip clearance

Patent metadata

Field	Value
Publication number	US-9709376-B2
Application number	US-201514710119-A
Country	US
Kind code	B2
Filing date	May 12, 2015
Priority date	May 12, 2014
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

A high sensitivity inductive sensor for measuring clearance of a rotating blade tip includes a one or more of sensing coils. The sensing coils are formed of magnet wire, which is wound to form planar spiral coils. Each of the coils are coupled in series with a function generator, which applies an excitation signal thereto. Accordingly, based on the change in impedance of the coils, a clearance measurement, which identifies the distance between the coil and the tip of the rotating blade can be obtained using predetermined calibration curve values.

First claim

What is claimed is:

1. A sensor for measuring a clearance of a tip of a rotating metallic structure, the sensor comprising:
a plurality of series coupled wire coils, each said wire coil coupled in parallel with a capacitor, and each said wire coil having a planar face that includes a plurality of coil turns; and
a controller coupled in series with said plurality of wire coils, said controller configured to generate a combined AC (alternating current) signal that includes a plurality of excitation signals that are each respectively associated with one of said plurality of wire coils;
wherein said controller simultaneously measures the change in inductance of said plurality of wire coils caused by the position of the tip of the rotating structure relative to said planar face of each of said plurality of wire coils, such that said change in inductance is associated by said controller with a measurement of the clearance between said planar face of each of said plurality of wire coils and the tip of the metallic structure.

2. The sensor of claim 1 , wherein said plurality of wire coils each comprise a spiral, square, rectangular, or hexagonal shape.

3. The sensor of claim 1 , wherein said plurality of wire coils each have 10 or less turns.

4. The sensor of claim 1 , wherein said plurality of wire coils each have 10 or more turns.

5. The sensor of claim 1 , wherein the sensor utilizes resonance frequency division multiplexing to format said excitation signals, such that said controller measures a voltage response of said plurality of wire coils to determine said change in inductance of each one of said plurality of wire coils.

6. The sensor of claim 1 , wherein said plurality of wire coils are each disposed between a first dielectric layer and a second dielectric layer.

7. The sensor of claim 6 , wherein said first and second dielectric layers are heat resistant.

8. The sensor of claim 6 , wherein said first dielectric layer and said second dielectric layer are formed of ceramic material.

9. The sensor of claim 1 , wherein each one said plurality of wire coils has a thickness of about 0.5 mm.

10. The sensor of claim 1 , wherein one or more of said plurality of wire coils comprises a plurality of coils that are stacked upon each other.

11. The sensor of claim 1 , wherein the metallic structure comprises a turbine blade.

12. The sensor of claim 1 , wherein the metallic structure comprises a compressor blade.

13. The sensor of claim 1 , wherein said plurality of excitation signals each has a resonance frequency that is respectively associated with one of said plurality of wire coils.

14. The sensor of claim 13 , wherein said controller measures a voltage response of said plurality of wire coils to determine said change in inductance of each one of said plurality of wire coils.

15. The sensor of claim 1 , wherein said wire coils are formed of magnet wire.

16. The sensor of claim 1 , wherein each said planar face of said plurality of coils is arranged so that the tip of the metallic structure passes across said plurality of wire coils.

17. A method of measuring clearance of a metallic structure comprising:
providing a detection circuit including a plurality of series coupled wire coils that are each coupled in parallel with a capacitor to form respective detection units, and each said coil having a planar face that includes a plurality of coil turns;
applying a combined AC (alternating current) signal to the plurality of series coupled coils, said combined AC signal including a plurality of excitation signals having a frequency that is the resonance frequency of the respective detection units;
moving a metallic structure relative to said coils;
identifying an output voltage of one or more of said detection units;
identifying a change in inductance of one or more of said coils based on said output voltage; and
determining a clearance distance between said planar face of one or more of said coils and the metallic structure based on said change in inductance of one or more of said coils.

18. The method of claim 17 , further comprising:
identifying a combined voltage response of said detection circuit; and
determining said output voltage of one or more of said detection units from said combined voltage response.

19. The method of claim 17 , wherein the metallic structure includes a tip, and said clearance distance determined is between said planar face of one or more of said coils and the tip of the metallic structure.

Assignees

• Zhe Jiang
• Du Li
• Univ Akron

Inventors

• Zhe Jiang
• Du Li

Classifications

• F01D21/003

  Arrangements for testing or measuring (for measuring vibrations G01H) · CPC title

• G01B7/14 Primary

  for measuring distance or clearance between spaced objects or spaced apertures (G01B7/30 takes precedence) · CPC title

• F01D11/20

  Actively adjusting tip-clearance · CPC title

• G01B7/023

  for measuring distance between sensor and object (G01B7/082 and G01B7/102 take precedence) · CPC title

• F01D21/04

  responsive to undesired position of rotor relative to stator {or to breaking-off of a part of the rotor}, e.g. indicating such position · CPC title