Position sensor incorporating a permanent magnet and a magnetism-sensitive ...

United States Patent [i9]

Oudet et al.

Illlllllllllllllllllllllll

US005532585A [ii] Patent Number: [45] Date of Patent:

■ III

5,532,585 Jul. 2, 1996

[54] POSITION SENSOR INCORPORATING A PERMANENT MAGNET AND A MAGNETISM-SENSITIVE PROBE AND INCLUDING PRIMARY AND SECONDARY AIR GAPS

[75] Inventors: Claude Oudet, Besancon; Daniel Prudham, Thise, both of France

[73] Assignee: Moving Magnet Technologies S.A.,

Besancon, France

[21] Appl. No.: 182,039

[22] PCT Filed: May 19, 1993

[86] PCT No.: PCT/FR93/00495

§ 371 Date: May 20,1994

§ 102(e) Date: May 20,1994 [87] PCT Pub. No.: WO93/23720

PCT Pub. Date: Nov. 25, 1993

[30] Foreign Application Priority Data

May 19, 1992 [FR] France 92 06052

[51] Int. CI.6 G01B 7/14; G01D 5/14

[52] U.S. CI 324/207.22; 324/207.2;

324/207.24

[58] Field of Search 324/207.11, 207.13,

324/207.14, 207.15, 207.20, 207.21, 207.22, 207.23, 207.24, 207.25, 232, 235, 239,

260, 262

[56] References Cited

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FOREIGN PATENT DOCUMENTS

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OTHER PUBLICATIONS

Hencke, "Analoge Halbleiter-Hallsensoren", CHIP Plus 5, May 1989, pp. 20-22.

Paret, "Les Capteurs Magneto-resistifs", Electronique Radio Plans, Jul. 1990, pp. 11-17.

Primary Examiner—Gerard R. Strecker

Attorney, Agent, or Firm—Obion, Spivak, McClelland,

Maier & Neustadt

[57] ABSTRACT

A position sensor which includes a stator presenting a slot forming a main air-gap inside which is positioned a permanent magnet, and including a sensor which features a magnetism-sensitive probe for measuring magnetic flow formed in a secondary air-gap. The permanent magnet is of a bipolar type and is movable inside the main thin air-gap delimited by ferromagnetic parts joined by non-magnetic connecting parts. The length of the main air-gap as measured along the direction of displacement of the movable magnet is at least 2(C+E), C designating the travel of the magnet and E designating the width of the main air-gap, the length of the magnet further being at least equal to (C+E) and its travel being at least ±C/2 with respect to the secondary air-gap perpendicular to the main air-gap.

9 Claims, 3 Drawing Sheets