Synchronous induction motor and manufacturing method and drive unit for the same, and hermetic electric compressor

Abstract

A synchronous induction motor features improved assemblability of a rotor, significantly reduced production cost, and improved operation performance of the motor. A plurality of die-cast secondary conductors is provided around a rotor yoke constituting the rotor of the synchronous induction motor. End rings are die-cast integrally with the secondary conductors on the peripheral portions of both end surfaces of the rotor yoke. Permanent magnets are inserted into slots formed such that they penetrate the rotor yoke. The openings of both ends of the slots are closed by a pair of end surface members formed of a non-magnetic constituent. One of the end surface members is secured to the rotor yoke by one of the end rings when the secondary conductors and the end rings are formed. The other end surface member is secured to the rotor yoke by a fixture.

What is claimed is:  
     
         1 . A synchronous induction motor comprising: 
 a stator equipped with a stator winding;    a rotor which is secured to a rotating shaft and which rotates in the stator;    a secondary conductor provided around the rotor yoke constituting the rotor; and    a permanent magnet embedded in the rotor yoke,    wherein a magnetic field produced by the permanent magnet does not pass through the rotating shaft.    
     
     
         2 . A synchronous induction motor comprising: 
 a stator equipped with a stator winding;    a rotor which is secured to a rotating shaft and which rotates in the stator;    a secondary conductor provided around the rotor yoke constituting the rotor; and    a permanent magnet embedded in the rotor yoke,    wherein a magnetic field produced by the permanent magnet bypasses the rotating shaft.    
     
     
         3 . A synchronous induction motor comprising: 
 a stator equipped with a stator winding;    a rotor which is secured to a rotating shaft and which rotates in the stator;    a secondary conductor provided around the rotor yoke constituting the rotor; and    a permanent magnet embedded in the rotor yoke,    wherein a magnetic field produced by the permanent magnet passes through only the rotor yoke, excluding the rotating shaft.    
     
     
         4 . The synchronous induction motor according to  claim 1 ,  claim 2 , or  claim 3 , wherein a void is formed in the rotor yoke between the permanent magnet and the rotating shaft.  
     
     
         5 . The synchronous induction motor according to  claim 1 ,  claim 2 , or  claim 3 , wherein a pair of the permanent magnets is disposed, sandwiching the rotating shaft therebetween, and permanent magnets for attracting the magnetic field produced by the paired permanent magnets are further disposed at both ends of a line that passes the paired permanent magnets and the rotating shafts.  
     
     
         6 . The synchronous induction motor according to  claim 1 ,  claim 2  or  claim 3 , wherein the permanent magnets are provided at both ends of a line that connects two magnetic poles, and the permanent magnets are radially disposed substantially about the rotating shaft.