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 rotating in the stator;    a plurality of secondary conductors which is positioned around a rotor yoke constituting the rotor and which is formed by die casting;    end rings which are positioned on the peripheral portions of both end surfaces of the rotor yoke and which are integrally formed with the secondary conductors by die casting;    a permanent magnet inserted in a slot formed such that it penetrates the rotor yoke; and    a pair of end surface members which is formed of a non-magnetic material and which closes the openings of both ends of the slot,    wherein one of the end surface members is secured to the rotor yoke by one of the end rings when the secondary conductors and end rings are formed, and the other end surface member is secured to the rotor yoke by a fixture.    
     
     
         2 . A synchronous induction motor comprising: 
 a stator equipped with a stator winding;    a rotor rotating in the stator;    a plurality of secondary conductors which is positioned around a rotor yoke constituting the rotor and which is formed by die casting;    end rings which are positioned on the peripheral portions of both end surfaces of the rotor yoke and which are integrally formed with the secondary conductors by die casting;    a permanent magnet inserted in a slot formed such that it penetrates the rotor yoke; and    a pair of end surface members which formed of a non-magnetic material and which closes the openings of both ends of the slot,    wherein non-magnetic members are disposed in contact with the inner sides of the two end rings to secure the two end surface members by pressing them against the rotor yoke by the non-magnetic members.    
     
     
         3 . A synchronous induction motor comprising: 
 a stator equipped with a stator winding;    a rotor rotating in the stator;    a plurality of secondary conductors which is positioned around a rotor yoke constituting the rotor and which is formed by die casting;    end rings which are positioned on the peripheral portions of both end surfaces of the rotor yoke and which are integrally formed with the secondary conductors by die casting;    a permanent magnet inserted in a slot formed such that it penetrates the rotor yoke; and    a pair of end surface members which is formed of a non-magnetic material and which closes the openings of both ends of the slot,    wherein a balancer formed into a predetermined shape beforehand is secured by a fixture to the rotor yoke together with the end surface member.    
     
     
         4 . A synchronous induction motor comprising: 
 a stator equipped with a stator winding;    a rotor rotating in the stator;    a plurality of secondary conductors which is positioned around a rotor yoke constituting the rotor and which is formed by die casting;    end rings which are positioned on the peripheral portions of both end surfaces of the rotor yoke and which are integrally formed with the secondary conductors by die casting;    a permanent magnet inserted in a slot formed such that it penetrates the rotor yoke; and    a pair of end surface members which is formed of a non-magnetic material and which closes the openings of both ends of the slot,    wherein a plurality of laminated sheet balancers is secured by a fixture to the rotor yoke together with the end surface member.    
     
     
         5 . A synchronous induction motor comprising: 
 a stator equipped with a stator winding;    a rotor rotating in the stator;    a plurality of secondary conductors which is positioned around a rotor yoke constituting the rotor and which is formed by die casting;    end rings which are positioned on the peripheral portions of both end surfaces of the rotor yoke and which are integrally formed with the secondary conductors by die casting;    a permanent magnet inserted in a slot formed such that it penetrates the rotor yoke; and    a pair of end surface members which is formed of a non-magnetic material and which closes the openings of both ends of the slot,    wherein at least one of the end surface members and a balancer are formed into one piece.    
     
     
         6 . A synchronous induction motor comprising: 
 a stator equipped with a stator winding;    a rotor rotating in the stator;    a plurality of secondary conductors which is positioned around a rotor yoke constituting the rotor and which is formed by die casting;    end rings which are positioned on the peripheral portions of both end surfaces of the rotor yoke and which are integrally formed with the secondary conductors by die casting;    a permanent magnet inserted in a slot formed such that it penetrates the rotor yoke;    a pair of end surface members which is formed of a non-magnetic material and which closes the openings of both ends of the slots; and    a balancer secured by being press-fitted to the inner side of at least one of the end rings.    
     
     
         7 . A synchronous induction motor comprising: 
 a stator equipped with a stator winding;    a rotor rotating in the stator;    a plurality of secondary conductors which is positioned around a rotor yoke constituting the rotor and which is formed by die casting;    end rings which are positioned on the peripheral portions of both end surfaces of the rotor yoke and which are integrally formed with the secondary conductors by die casting;    a permanent magnet inserted in a slot formed such that it penetrates the rotor yoke; and    a pair of end surface members which is formed of a non-magnetic material and which closes the openings of both ends of the slot in which the permanent magnet has been inserted,    wherein the two end surface members are secured to the rotor yoke by the two end rings when the secondary conductors and the end rings are formed.    
     
     
         8 . 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.    
     
     
         9 . 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.    
     
     
         10 . 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.    
     
     
         11 . The synchronous induction motor according to  claim 8 ,  claim 9 , or  claim 10 , wherein a void is formed in the rotor yoke between the permanent magnet and the rotating shaft.  
     
     
         12 . The synchronous induction motor according to  claim 8 ,  claim 9 ,  claim 10 , or  claim 11 , 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 shaft.  
     
     
         13 . The synchronous induction motor according to  claim 8 ,  claim 9 ,  claim 10 , or  claim 11 , 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.  
     
     
         14 . A synchronous induction motor comprising: 
 a stator equipped with a stator winding;    a rotor rotating in the stator;    a secondary conductor provided around the rotor yoke constituting the rotor; and    a permanent magnet embedded in the rotor yoke,    wherein the permanent magnet is magnetized by current passed through the stator winding.    
     
     
         15 . The synchronous induction motor according to  claim 14 , wherein the permanent magnet is made of a rare earth type magnet or a ferrite magnet.  
     
     
         16 . The synchronous induction motor according to  claim 14  or  claim 15 , wherein 
 the stator winding is of a single-phase configuration and has a primary winding and an auxiliary winding, and  
 the permanent magnet is magnetized by the current passed through either the primary winding or the auxiliary winding.  
 
     
     
         17 . The synchronous induction motor according to  claim 14  or  claim 15 , wherein 
 the stator winding is of a three-phase configuration that includes a three-phase winding, and  
 the permanent magnet is magnetized by current passed through a single phase, two phases, or three phases of the stator windings.  
 
     
     
         18 . The synchronous induction motor according to  claim 14 ,  claim 15 ,  claim 16 , or  claim 17 , wherein the stator winding is coated with varnish or a sticking agent that is heated to fuse the winding.  
     
     
         19 . The synchronous induction motor according to  claim 1 ,  claim 2 ,  claim 3 ,  claim 4 ,  claim 5 ,  claim 6 ,  claim 7 ,  claim 8 ,  claim 9 ,  claim 10 ,  claim 11 ,  claim 12 ,  claim 13 ,  claim 14 ,  claim 15 ,  claim 16 ,  claim 17 , or  claim 18 , which is installed in a compressor.  
     
     
         20 . The synchronous induction motor according to  claim 19 , wherein the compressor is used with an air conditioner or an electric refrigerator or the like.  
     
     
         21 . A manufacturing method for a synchronous induction motor that has a stator equipped with a stator winding, a rotor rotating in the stator, a secondary conductor provided around a rotor yoke constituting the rotor, and a permanent magnet embedded in the rotor yoke, the manufacturing method comprising: 
 a step for embedding a magnet constituent for the permanent magnet in the rotor yoke; and    a step for passing current through the stator winding to magnetize the magnet constituent.    
     
     
         22 . The manufacturing method for the synchronous induction motor according to  claim 21 , wherein a rare earth type or ferrite material is used for the magnet constituent.  
     
     
         23 . The manufacturing method for the synchronous induction motor according to  claim 21  or  claim 22 , wherein 
 the stator winding is of a single-phase configuration and has a primary winding an auxiliary winding, and  
 the permanent magnet is magnetized by the current passed through either the primary winding or the auxiliary winding.  
 
     
     
         24 . The manufacturing method for the synchronous induction motor according to  claim 21  or  claim 22 , wherein 
 the stator winding is of a three-phase configuration that includes a three-phase winding, and  
 the permanent magnet is magnetized by current passed through a single phase, two phases, or three phases of the stator windings.  
 
     
     
         25 . The manufacturing method for the synchronous induction motor according to  claim 21 ,  claim 22 ,  claim 23 , or  claim 24 , wherein the stator winding is coated with varnish or a sticking agent that is heated to fuse the windings.  
     
     
         26 . In a synchronous induction motor comprising: 
 a stator equipped with a stator winding constructed of a primary winding and an auxiliary winding;    a rotor rotating in the stator;    a secondary conductor provided around a rotor yoke constituting the rotor; and    a permanent magnet embedded in the rotor yoke,    a drive unit for the synchronous induction motor, comprising:    an operating capacitor connected to the auxiliary winding; and    a series circuit of a start-up capacitor and a PTC, which is connected in parallel to the operating capacitor.    
     
     
         27 . In a synchronous induction motor comprising: 
 a stator equipped with a stator winding formed of a primary winding and an auxiliary winding;    a rotor rotating in the stator;    a secondary conductor provided around a rotor yoke constituting the rotor; and    a permanent magnet embedded in the rotor yoke,    a drive unit for the synchronous induction motor, comprising:    an operating capacitor connected to the auxiliary winding; and    a PTC connected in parallel to the operating capacitor.    
     
     
         28 . In a synchronous induction motor comprising: 
 a stator equipped with a stator winding formed of a primary winding and an auxiliary winding;    a rotor rotating in the stator;    a secondary conductor provided around a rotor yoke constituting the rotor; and    a permanent magnet embedded in the rotor yoke,    a drive unit for the synchronous induction motor, comprising:    an operating capacitor connected to the auxiliary winding; and    a series circuit of a start-up capacitor and a start-up relay contact, which is connected in parallel to the operating capacitor.    
     
     
         29 . In a synchronous induction motor comprising: 
 a stator equipped with a stator winding formed of a primary winding and an auxiliary winding;    a rotor rotating in the stator;    a secondary conductor provided around a rotor yoke constituting the rotor; and    a permanent magnet embedded in the rotor yoke,    a drive unit for the synchronous induction motor, comprising:    an operating capacitor connected to the auxiliary winding.    
     
     
         30 . A hermetic electric compressor comprising a compression unit and an electric unit for driving the compression unit in a hermetic vessel, wherein 
 the electric unit is secured to the hermetic vessel and constituted by a stator equipped with a stator winding and a rotor rotating in the stator,    the rotor comprises a secondary conductor provided around a rotor yoke and a permanent magnet embedded in the rotor yoke, and    a thermal protecting means for cutting off the supply of current to the electric unit in response to a predetermined temperature rise is provided in the hermetic vessel.    
     
     
         31 . The hermetic electric compressor according to  claim 30 , wherein the thermal protecting means is installed on the stator winding.  
     
     
         32 . A hermetic electric compressor comprising a compression unit and an electric unit for driving the compression unit in a hermetic vessel, wherein 
 the electric unit is secured to the hermetic vessel and constituted by a stator equipped with a stator winding and a rotor rotating in the stator,    the rotor comprises a secondary conductor provided around a rotor yoke and a permanent magnet embedded in the rotor yoke, and    a thermal protecting means for cutting off the supply of current to the electric unit in response to a predetermined temperature rise is provided on the outer surface of the hermetic vessel.    
     
     
         33 . The hermetic electric compressor according to  claim 30 ,  claim 31 , or  claim 32 , wherein the thermal protecting means is constructed of a thermistor whose resistance value varies with temperature and a controller that controls the supply of current to the electric unit according to a change in the resistance value of the thermistor.  
     
     
         34 . The hermetic electric compressor according to  claim 30 ,  claim 31 , or  claim 32 , wherein the thermal protecting means is constructed of a bimetal switch.  
     
     
         35 . The hermetic electric compressor according to  claim 30 ,  claim 31 , or  claim 32 , wherein the thermal protecting means is constructed of a thermostat that opens/closes a contact according to temperature.  
     
     
         36 . A hermetic electric compressor comprising a compression unit and an electric unit for driving the compression unit in a hermetic vessel, wherein 
 the electric unit is secured to the hermetic vessel and constituted by a stator equipped with a stator winding and a rotor rotating in the stator,    the rotor comprises a secondary conductor provided around a rotor yoke and a permanent magnet embedded in the rotor yoke, and    a thermal protecting means for cutting off the supply of current to the electric unit at a predetermined overload current is provided.    
     
     
         37 . The hermetic electric compressor according to claim  36 , wherein the overload protecting means is constituted by an overload switch.  
     
     
         38 . The hermetic electric compressor according to  claim 36 , wherein the overload protecting means is constituted by a current transformer for detecting the current supplied to the electric unit and a controller for controlling the supply of current to the electric unit on the basis of an output of the current transformer.  
     
     
         39 . The hermetic electric compressor according to  claim 33  or  claim 38 , wherein the controller cuts off the supply of current to the electric unit after a predetermined time elapses since a temperature or current exceeded a predetermined value.  
     
     
         40 . The hermetic electric compressor according to  claim 39 , wherein the controller restarts the supply of current to the electric unit after waiting for the elapse of a predetermined delay time since the supply of current to the electric unit was cut off.