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. 12, 1990
Filed:
Jun. 05, 1989
Kubota, Ltd., Osaka, JP;
Abstract
A magneto-strictive torque sensor for electrically contactlessly detecting a torque applied to a rotary shaft on the basis of a resulting change in the magnetic permeability of the surface of the shaft. Fine dents and retainer areas for retaining residual compressive stress due to the fine dents are formed on the surface of the rotary shaft. According to this arrangement, the process of magnetization resulting from the application of an exciting magnetic field and of the torque to the rotary shaft involves less magnetization due to magnetic domain wall displacement and consists principally of reversible magnetic rotation, with the result of reduced hysteresis in the magnetization process. The reduced hysteresis causes less hysteresis involved in torque detection and higher detection sensitivity, thus resulting in high accuracy of torque detection. Further, by working the surface of the rotary shaft for the purpose of forming the fine dents thereon, microdefects present on the surface layer of the rotary shaft are reduced or eliminated and thus reduced hysteresis and improved sensitivity can be attained in the process of torque detection.