Linkage of position sensor

• US 6,018,241 A
• Filed: 02/17/1998
• Issued: 01/25/2000
• Est. Priority Date: 10/18/1994
• Status: Expired due to Term

• Current Assignee: CTS Corporation
• Original Assignee: CTS Corporation
• Inventors: Campbell, Robert J., McCurley, Jeffrey L., White, James E., Jarrard, Craig A., Zdanys, John Jr.
• Primary Examiner(s): PATIDAR, JAY M
• Application Number:
  US09/025,015
• Time in Patent Office: 707 Days
• Field of Search: 324/207.2, 324/207.21-207.24, 324/207.26, 324/173, 324/174, 324/207.25, 338/38 R, 338/32 H
• US Class Current: 324/207.2
• CPC Class Codes: G01B 7/02 for measuring length, width or thickness G01B7/004, G01B7/12 take precedence
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

An extremely reliable and effective position sensor is provided at low cost for determining the relative position of a mechanical linkage with respect to a reference point. The position sensor includes a rotor or bracket which is mechanically coupled to the linkage and contains at least two magnets on opposite walls adjacent a channel opening. The opposing magnets are formed with first and second sloped or ramped sections which produce produce variable magnetic fields as determined by the geometric profile of the magnets. One or more detectors are positioned in the air gap between the opposing magnets. As the linkage is moved, the rotor or bracket moves with respect to the detector causing a change in the strength of the magnetic field detected by the detector whereby the detector determines the position of the movable linkage.

Claims

1. A sensor for detecting a position of a movable piece relative to a reference point, comprising:

a) a c-shaped magnetically permeable bracket, attached to the movable piece and having a first and second spaced apart flanges disposed opposite and parallel to each other, the first and second flanges interconnected by a central flange and a distal end;

b) a first and second tapered opposed magnet attached to the first and second flanges and extending along the length thereof, respectively, each tapered magnet having;

b1) an inclined surface having a thin end located substantially at the distal end of the flanges; and

b2) a plateau located substantially at the proxil end of the flanges;

c) a variable width air gap being defined between the inclined surfaces of the first and second tapered magnets, the first and second tapered magnets, the bracket and the air gap forming a continuous magnetic circuit and producing a variable magnetic field density within the air gap that varies from a low magnitude near the distal end of the flanges to a high magnitude near the proxil end of the flanges; and

d) at least one hall effect magnetic field detector fixedly positioned in the variable width air gap between the first and second magnets for generating an electrical signal representative of the position of the movable piece with respect to the reference point.

2. The sensor according to claim 1, wherein the movable piece moves in a linear motion.

3. The sensor according to claim 1, wherein the movable piece moves in a rotary motion.

4. The sensor according to claim 1, wherein the electrical signal increases or decreases linearly as the movable piece moves when the hall effect detector is located adjacent the inclined surfaces.

5. The sensor according to claim 4, wherein the electrical signal is constant as the movable piece moves when the hall effect detector is located adjacent the plateaus.