Permanent magnet motor

• US 20050264122A1
• Filed: 05/20/2005
• Published: 12/01/2005
• Est. Priority Date: 05/26/2004
• Status: Active Grant

• Current Assignee: Oriental Motor Company Limited
• Original Assignee: Oriental Motor Company Limited
• Inventors: Domeki, Hideo, Yamanaka, Yoshiyasu
• Granted Patent: US 7,425,785 B2
• Time in Patent Office: Days
• US Class Current: 310/156.460
• CPC Class Codes: H02K 1/2781 Magnets shaped to vary the mechanical air gap between the magnets and the stator

Abstract

In a permanent magnet motor consisting of a rotor 1, which is supported on a rotating shaft 2 and has twelve permanent magnets 3 arranged at fixed intervals in the circumferential direction in the peripheral edge portion thereof, and a stator 4, which is disposed around the rotor 1 with a gap being provided with respect to the rotor 1 and has nine magnetic poles 4a, each having a coil wound thereon, arranged at fixed intervals in the circumferential direction so as to face towards the outer peripheral surface of the rotor 1,

• • a value obtained by dividing the radius of the rotor 1 by the radius of curvature of a permanent magnet surface facing towards the stator is set at a value such as to decrease cogging torque. Thereby, there is provided a permanent magnet motor in which the radius of an arcuate shape which can minimize cogging torque is theoretically verified, by which the optimum radius can be determined limitedly for a permanent magnet motor consisting of a rotor having twelve permanent magnets and a stator having nine magnetic poles.

Claims

1. A permanent magnet motor consisting of a rotor, which is supported on a rotating shaft and has twelve permanent magnets arranged at fixed intervals in the circumferential direction in the peripheral edge portion thereof, and a stator, which is disposed around the rotor with a gap being provided with respect to the rotor and has nine magnetic poles, each having a coil wound thereon, arranged at fixed intervals in the circumferential direction so as to face towards the outer peripheral surface of the rotor, wherein

a value obtained by dividing the radius of the rotor by the radius of curvature of a permanent magnet surface facing towards the stator is set at a value such as to decrease cogging torque.

2. The permanent magnet motor according to claim 1, wherein the value obtained by dividing the radius of rotor by the radius of curvature of a permanent magnet surface facing towards a stator is set in the range of 2.55 to 2.7.

3. The permanent magnet motor according to claim 1, wherein the value obtained by dividing the radius of rotor by the radius of curvature of a permanent magnet surface facing towards a stator is set at 2.6.