The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 11, 1991
Filed:
Nov. 08, 1989
Andrzej M Pawlak, Troy, MI (US);
Takeshi Shirai, Anderson, IN (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A variable reluctance rotation sensor comprises a rotatable toothed wheel and a magnetic pickup assembly comprising a pair of permanent magnets each having a pair of poles with an opposite one of said poles adjacent the toothed wheel. The permanent magnets are separated from each other by an arc equal to the arc between two of the teeth and joined by a magnetic flux member with a multi-turn electrical coil wound thereon. The flux member establishes a common main flux loop through the first and second permament magnets but also extends close to the toothed wheel to further establish additional flux loops separately through each of the permanent magnets. Passage of alternating teeth and slots as the wheel rotates produces a spatial fluctuation in the additional flux loops between the magnets to vary the flux linkages with individual coil turns and increase the electrical signal in the coil over the signal level that would be produced by variations in air gap of the common flux loop alone. The sensor produces a rotational speed signal at very low rotational speeds of greater amplitude and/or with a larger minimum air gap than that of conventional variable reluctance sensors.