Motor-driven compressor

Abstract

A compression mechanism is provided, in a casing, and operatively coupled via a drive shaft 17 to an electric motor 21 accommodated in a motor chamber 15 within the casing, so that power can be transmitted. An in-shaft bore 17 A is formed in the drive shaft and a first bifurcated hole 17 B is formed for communicating the in-shaft bore 17 A to the motor chamber 15 . The in-shaft bore 17 A is communicated to the suction chamber 31 via a second collecting hole 13 F, the collecting chamber 13 D and a suction communication hole 13 G formed in a cylinder block 13 . Thereby, part of the refrigerant sucked in the casing is introduced to the compression mechanism through a gap between a stator 19 and a rotor 20 , and the remainder of the refrigerant is introduced to the compression mechanism without being used for cooling the electric motor 21.

1 . A motor-driven compressor comprising, in a casing, a compression mechanism for compressing refrigerant, an electric motor having a stator and a rotor and disposed in a motor chamber in the casing, and a drive shaft connected to the rotor and transmitting a drive force of the electric motor to the compression mechanism, wherein 
 the motor chamber and an in-shaft refrigerant passage formed in the drive shaft are provided in a suction passage for introducing the refrigerant sucked into the casing to the compression mechanism, and    wherein part of the sucked refrigerant is introduced to the compression mechanism while passing through a gap between the stator and the rotor, and the other of the sucked refrigerant is introduced to the compression mechanism without passing through the gap between the stator and the rotor but while passing through the in-shaft refrigerant passage.    
     
     
         2 . A motor-driven compressor according to  claim 1 , wherein at least one of a drive shaft bearing for rotationally supporting the drive shaft in the casing and a bearing for supporting part or all of the compression mechanism is disposed in the suction passage.  
     
     
         3 . A motor-driven compressor according to  claim 1 , wherein a suction opening for sucking the refrigerant into the casing is provided in the motor chamber on the axis of the drive shaft.  
     
     
         4 . A motor-driven compressor according to  claim 1 , wherein the in-shaft refrigerant passage is formed through opposite ends of the drive shaft.  
     
     
         5 . A motor-driven compressor according to  claim 1 , wherein the compression mechanism is of a scroll type in which a stationary spiral wall formed in a stationary scroll provided on a side of the casing is meshed with a movable spiral wall formed in a movable scroll operatively coupled to the drive shaft so that the movable scroll is subjected to an orbital motion as the drive shaft rotates to compress the refrigerant, wherein an in-scroll refrigerant passage is formed in the movable scroll so that at least part of the refrigerant introduced into the in-shaft refrigerant passage is introduced into a compression chamber defined between both the spiral walls through the in-scroll refrigerant passage.  
     
     
         6 . A motor-driven compressor according to  claim 1 , wherein the compression mechanism is of a reciprocating piston type in which a piston accommodated for reciprocation in a cylinder bore formed in the casing is operatively coupled to the drive shaft to compress the refrigerant by the reciprocation of the piston as the drive shaft rotates.