System for sensing the position of a rotating steel shaft including a track formed by a strip having discontinuous electrical properties, and a method of manufacturing such a track

• US 5,200,698 A
• Filed: 01/16/1990
• Issued: 04/06/1993
• Est. Priority Date: 01/17/1989
• Status: Expired due to Fees

• Current Assignee: GEC Alsthom SA
• Original Assignee: GEC Alsthom SA
• Inventors: Thibaud, Marc
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US07/465,862
• Time in Patent Office: 1,176 Days
• Field of Search: 324/164, 324/173, 324/174, 324/207.16, 324/207.22, 324/207.25, 341/15, 340/671, 340/672, 340/686, 29/592.1, 156/60, 156/292, 156/307.7
• US Class Current: 324/207.22
• CPC Class Codes: G01D 5/202 by movable a non-ferromagnetic conductive element G01D5/2033 takes precedence
• CPC Class Codes: G01P 3/481 of pulse signals
• CPC Class Codes: G01P 3/49 using eddy currents
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A system for sensing the position of a rotating steel shaft (1), the system comprising an eddy current sensor and a track (3) fixed to the shaft and going past the sensor, the track being constituted by a strip (4) of electrical insulation material having areas of non-ferromagnetic material with good electrical conductivity regularly distributed around the shaft, wherein the face of the strip (4) provided with the areas of non-ferromagnetic material is glued to the shaft (1). This very simple system serves to obtain a signal of larger amplitude.

Claims

1. A system for sensing the position of a rotating steel shaft, the system comprising an eddy current sensor and a track fixed to the shaft and going past the sensor, the track being constituted by a strip of electrical insulation material having areas of non-ferromagnetic material with good electrical conductivity regularly distributed around the shaft, wherein the face of the strip provided with the areas of non-ferromagnetic material is glued close to the shaft and isolated from the shaft.

2. A sensing system according to claim 1, wherein the areas are made of copper.

3. A method of manufacturing a track having areas of non-ferromagnetic metal material on a steel shaft, said track being adapted for use in determining the rotational position of said shaft by sensing the metal areas, said method comprising the steps of:

forming a strip of electrical insulating material having regularly distributed areas of non-ferromagnetic metal on one face thereof, and gluing said strip to the periphery of said shaft with the areas of non-ferromagnetic metal facing the shaft and isolated therefrom by said glue.