Motor and its permanent magnet

Abstract

The challenge to be solved by the present invention is the miniaturization of a 1-300 W class of motor. This can be achieved by using a hollow-cylinder shaped anisotropic bonded magnet magnetized in a 4-pole configuration. The anisotropic bonded magnet has a maximum energy product approximately 4 times greater than the conventional sintered ferrite magnets. The use of a 4-pole configuration shortens the magnetic path length of the individual magnetic circuits and the magnetic force contributing to the torque is increased. When the torque is kept the same as in the conventional motor, the length of the electromagnetic rotor core and the axial magnet length can be reduced. In this fashion, 1-300 W class motors can be reduced in size.

1 - 20 . (Cancelled)  
     
     
         21 . A DC brush motor with a superior motor performance index (torque constant/motor volume) comprising: 
 a permanent magnet, arranged on an inner perimeter of a housing, the permanent magnet being formed as a thin-walled hollow cylinder shaped anisotropic rare earth bonded magnet having a maximum energy product greater than 14 MGOe and magnetized with at least 4 magnetic poles; and    an electromagnetic rotor core arranged in the center of the motor.    
     
     
         22 . A DC brush motor according to  claim 21 , wherein output power of said DC brush motor is in a range from 1 to 300 W.  
     
     
         23 . A DC brush motor with a superior motor performance index (torque constant/motor volume) comprising: 
 a permanent magnet, arranged on an inner perimeter of a housing, the permanent magnet being formed as a thin-walled hollow cylinder shaped anisotropic rare earth bonded magnet having a maximum energy product greater than 17 MGOe and magnetized with at least 4 magnetic poles; and    an electromagnetic rotor core arranged in the center of the motor.    
     
     
         24 . A DC brush motor according to  claim 23 , wherein output power of said DC brush motor is in a range from 1 to 300 W.  
     
     
         25 . A DC brush motor with a superior motor performance index (torque constant/motor volume) comprising: 
 a permanent magnet, arranged on an inner perimeter of a housing, the permanent magnet being formed as a thin-walled hollow cylinder shaped anisotropic rare earth bonded magnet having a maximum energy product greater than 25 MGOe and magnetized with at least 4 magnetic poles; and    an electromagnetic rotor core arranged in the center of the motor.    
     
     
         26 . A DC brush motor according to  claim 25 , wherein output power of said DC brush motor is in a range from 1 to 300 W.