Importance

Loading Importance Indicators...

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.

Loading the Abstract Image...

First Claim