Electric compressor

Abstract

There is provided an electric compressor includes a compression mechanism, an electric motor, a motor housing having an injection port that communicates with one of compression chambers that is in the middle of the compression, a discharge housing having a discharge chamber into which compressed refrigerant is discharge, and an intermediate pressure housing disposed between the motor housing and the discharge housing. The intermediate pressure housing has an introduction port for introducing intermediate pressure refrigerant from an external refrigerant circuit and a communication passage between the introduction port and the injection port of the motor housing. The introduction port and the communication passage cooperate with the injection port to allow the intermediate pressure refrigerant to be injected into the compression chamber. The communication passage has in the middle thereof a muffler chamber. A partition member separates the muffler chamber and the discharge chamber.

What is claimed is: 
     
         1 . An electric compressor comprising:
 a compression mechanism having a plurality of compression chambers;   an electric motor driving the compression mechanism to draw refrigerant into the compression chambers and compress the refrigerant in the compression chambers;   a motor housing accommodating the electric motor and the compression mechanism, the motor housing having an injection port that communicates with one of the compression chambers, the compression chamber being in the middle of the compression;   a discharge housing having a discharge chamber into which the compressed refrigerant is discharge; and   an intermediate pressure housing disposed between the motor housing and the discharge housing, the intermediate pressure housing having an introduction port for introducing intermediate pressure refrigerant from an external refrigerant circuit and a communication passage that provides communication between the introduction port and the injection port of the motor housing, wherein the introduction port and the communication passage cooperate with the injection port to allow the intermediate pressure refrigerant to be injected into the compression chamber, wherein the communication passage has in the middle thereof a muffler chamber whose volume is large than volume of the communication passage other than the muffler chamber, wherein pressure of the intermediate pressure refrigerant is higher than pressure of the drawn refrigerant and lower than pressure of the compressed refrigerant discharged into the discharge chamber, wherein a partition member separates the muffler chamber and the discharge chamber.   
     
     
         2 . The electric compressor according to  claim 1 , wherein the partition member has a bottom plate and a side wall that extends from the bottom plate toward the intermediate pressure housing and is surrounded by the discharge chamber. 
     
     
         3 . The electric compressor according to  claim 1 , wherein each of the motor housing, the discharge housing and the intermediate pressure housing has a bolt fastening hole, wherein a bolt is inserted in the bolt fastening holes of the motor housing, the discharge housing and the intermediate pressure housing to fasten the motor housing, the discharge housing and the intermediate pressure housing together. 
     
     
         4 . The electric compressor according to  claim 1 , wherein a recess is formed in the intermediate pressure housing side of the discharge housing so as to expand a volume of the discharge chamber, wherein the recess partially surrounds the muffler chamber. 
     
     
         5 . The electric compressor according to  claim 1 , wherein the discharge housing has therein a projection that is formed extending toward the partition member, wherein a clearance is formed between the projection and the partition member so as to restrict flow of the compressed refrigerant from the discharge chamber to the communication passage. 
     
     
         6 . The electric compressor according to  claim 5 , wherein the projection has therein a communication passage through which an outlet port is in communication with the discharge chamber, wherein the partition member has therein a recess in which the projection is inserted, wherein the communication passage of the projection has an opening in the recess, wherein the clearance is formed between the projection and the recess of the partition member.