Motor-driven compressor

Abstract

The motor-driven compressor includes a housing, a compression mechanism, a rotary shaft and an electric motor all disposed in the housing, a protective film and a fixing resin. The electric motor is adapted to rotate the rotary shaft thereby to drive the compression mechanism. The electric motor has a rotor fixed on the rotary shaft and a stator supported by the housing. The rotor has a permanent magnet and a magnet hole in which the permanent magnet is inserted. The magnet hole extends in an axial direction of the rotor. The protective film is formed on a surface of the permanent magnet for improving corrosion resistance of the permanent magnet. The fixing resin is filled in at least part of a gap between the permanent magnet and a wall of the magnet hole for fixing the permanent magnet to the wall of the magnet hole.

What is claimed is: 
     
         1 . A motor-driven compressor comprising:
 a housing having a suction port and a discharge port;   a compression mechanism disposed in the housing, the compression mechanism being adapted to compress refrigerant drawn into the housing through the suction port and to discharge the compressed refrigerant out of the housing through the discharge port;   a rotary shaft disposed in the housing;   an electric motor disposed in the housing, the electric motor being adapted to rotate the rotary shaft thereby to drive the compression mechanism, the electric motor having a rotor fixed on the rotary shaft and a stator supported by the housing, the rotor having a permanent magnet and a magnet hole in which the permanent magnet is inserted, the magnet hole extending in an axial direction of the rotor;   a protective film formed on a surface of the permanent magnet for improving corrosion resistance of the permanent magnet; and   a fixing resin filled in at least part of a gap between the permanent magnet and a wall of the magnet hole for fixing the permanent magnet to the wall of the magnet hole.   
     
     
         2 . The motor-driven compressor according to  claim 1 , wherein the magnet hole has a main hole corresponding in shape to a contour of the permanent magnet and an expanded hole expanded outward from part of a wall of the main hole, wherein the expanded hole is opened at least at one end thereof in the axial direction of the rotor and filled with the fixing resin. 
     
     
         3 . The motor-driven compressor according to  claim 1 , wherein the protective film formed on the surface of the permanent magnet has a chemical adsorption film having at least one of hydroxy group and amino group. 
     
     
         4 . The motor-driven compressor according to  claim 1 , wherein the protective film formed on the surface of the permanent magnet has a film made of a metal. 
     
     
         5 . The motor-driven compressor according to  claim 1 , wherein the protective film formed on the surface of the permanent magnet has a film made of a resin. 
     
     
         6 . The motor-driven compressor according to  claim 1 , wherein the permanent magnet is a rare-earth magnet. 
     
     
         7 . The motor-driven compressor according to  claim 1 , wherein the motor-driven compressor is used for a vehicle-mounted air conditioner having a refrigerant circulation path in which a nonmetallic duct is connected. 
     
     
         8 . The motor-driven compressor according to  claim 1 , wherein the motor-driven compressor is used in a refrigeration system through which the refrigerant that is expressed by molecular formula of C 3 H m F n  having one double bond in a molecular structure of the molecular formula, wherein m is an integral number of 1 to 5, n is an integral number of 1 to 5, and m+n=6, or a mixed refrigerant containing the refrigerant circulates. 
     
     
         9 . The motor-driven compressor according to  claim 1 , wherein the housing has therein lubricating oil containing at least one of polyolester (POE), polyvinyl ether (PVE) and polyalkylene glycol (PAG). 
     
     
         10 . The motor-driven compressor according to  claim 1 , wherein the rotor has a rotor body and a pair of end plates, the magnet hole of the rotor extending through the rotor body in an axial direction of the rotor body, the paired end plates being disposed at opposite ends in the axial direction of the rotor body for closing the magnet hole. 
     
     
         11 . The motor-driven compressor according to  claim 10 , wherein an entire outer surface of the rotor is coated with a resin film.