Permanent magnet motor for driving a fan

Abstract

A permanent magnet motor for driving a fan is rotated while a movement of the rotor in a direction of thrust of a rotary shaft with a rotation of the fan is prevented by magnetic attraction force of a permanent magnet and a stator core. A surface magnetic flux density of the permanent magnet facing the stator core is lower at an end portion than at a central portion of the permanent magnet in the direction of thrust of the rotary shaft.

1 - 4 . (canceled)  
   
   
       5 . A permanent magnet motor for driving a fan, comprising: 
 a rotor including a permanent magnet;    a stator including a stator core having a stator winding;    a bearing for rotatably supporting a rotary shaft of said rotor; and    a fan arranged on said rotor;    wherein said fan is rotated while a movement of said rotor in a direction of thrust of the rotary shaft with a rotation of said fan is prevented by a magnetic attraction force of the permanent magnet and the stator core; and    wherein the permanent magnet has an opposed portion in opposed relation with an end surface of the stator core in a direction of thrust of the rotary shaft, and the magnetic attraction force of the opposed portion and the stator core prevents a movement of said rotor in the direction of thrust of the rotary shaft.    
   
   
       6 - 9 . (canceled)  
   
   
       10 . A permanent magnet motor for driving a fan, comprising: 
 a rotor including a permanent magnet;    a stator including a stator core having a stator winding;    a bearing for rotatably supporting a rotary shaft of said rotor; and    a fan arranged on said rotor;    wherein the fan is rotated while preventing, by a magnetic attraction force of the permanent magnet and the stator core, said rotor moving in a direction of thrust of the rotary shaft with a rotation of said fan; and    wherein a surface magnetic flux density of the permanent magnet facing the stator core is lower at an end portion than at a central portion of the permanent magnet along the direction of thrust of the rotary shaft, and wherein a gap between the rotor and the stator is constantly maintained at opposite surfaces with a flux density of the gap being variable.    
   
   
       11 . The permanent magnet motor recited in  claim 10 , wherein no feedback control is provided which results in the elimination of complicated control.  
   
   
       12 . The permanent magnet motor recited in  claim 11 , wherein said no feedback control further comprises winding current and voltage.