Method for measuring a gap between a proximity probe and a conductive target material

• US 6,798,194 B2
• Filed: 05/30/2003
• Issued: 09/28/2004
• Est. Priority Date: 10/22/1999
• Status: Expired due to Fees

• Current Assignee: Bently Nevada Incorporated (General Electric Company)
• Original Assignee: Bently Nevada Incorporated (General Electric Company)
• Inventors: Slates, Richard D.
• Primary Examiner(s): Zarnela, David A.
• Assistant Examiner(s): KOBERT, RUSSELL MARC
• Application Number:
  US10/452,702
• Publication Number:
  US 20030210039A1
• Time in Patent Office: 487 Days
• Field of Search: 324/207.11, 324/207.13, 324/207.15, 324/207.16, 324/222, 324/228, 324/603, 324/609, 324/662, 324/671, 324/691, 324/693, 324/699, 324/715, 324/716, 324/722, 324/724, 702/65, 702/155, 702/158, 702/166
• US Class Current: 324/207.11
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01B 7/023 for measuring distance between sensor and object G01B7/082 and G01B7/102 take precedence
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
• CPC Class Codes: G01D 5/202 by movable a non-ferromagnetic conductive element G01D5/2033 takes precedence
• CPC Class Codes: G01N 27/9046 by analysing electrical signals

Abstract

A digital eddy current proximity system including a digital impedance measuring device for digitally measuring the proximity probes impedance correlative to displacement motion and position of a metallic target object being monitored. The system further including a cable-length calibration method, an automatic material identification and calibration method, a material insensitive method, an inductive ratio method and advanced sensing characteristics.

Claims

1. A method for measuring a gap between a proximity probe and a conductive target material, the steps including:

providing a database of normalized impedance curve representations for different conductive target materials;

measuring an impedance of a proximity probe located proximate a conductive target material being identified;

normalizing the measured probe impedance;

utilizing the normalized probe impedance and the database of normalized impedance curve representations for identifying the conductive target material;

determining a gap value between the proximity probe and the conductive target material from the normalized probe impedance and the identified target material.

2. The method of claim 1 wherein the step of providing a database of normalized impedance curve representations for different conductive target materials includes providing at least one lookup table storing values of each normalized impedance curve for each different target material.

3. The method of claim 2 wherein the step of providing a database of normalized impedance curve representations for different conductive target materials includes providing at least one equation in the database to represent normalized impedance curves for different target materials.