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:
Dec. 22, 1987
Filed:
Jun. 30, 1986
Claude Oudet, Besancon, FR;
Portescap, La Chaux-de-fonds, CH;
Abstract
An electric motor which delivers a high torque per Ampere-turn and a high power rate and acceleration of the rotor. Maximum torque per Ampere-turn is accomplished by setting a minimum air-gap width in the range defined by the relationship 0.389 P+1.4.ltoreq.P/E.ltoreq.0.706 P+1.85, with P being the space in millimeters between the centers of the magnetic poles of like polarities of a multipolar permanent magnet arrangement disposed on the rotor and between the centers of regions of minimum width of the air-gap, and E being the width in millimeters of the air-gap. The air-gap refers to the space between opposite parts of permeable magnetic material and thus defines the entire space in which a permanent magnet is placed. In one construction of the invention, the motor comprises a flat annular disk mounted for rotation on a motor shaft, and the stator comprises a plurality of tooth-shaped polar portions facing other polar portions on either side of the annular disk in a direction parallel to the shaft of the disk. The annular disk contains portions of alternating polarity which sequentially pass the tooth-shaped polar portions during rotation of the disk. It is further advantageous to increase the air-gap width E slightly from the inner part to the outer part of the circumference of the annular disk. Thus, the present invention enables small air-gaps and thin permanent magnets to be used to provide very good dynamic characteristics such as power rate and acceleration.