Motor-operated compressor

Abstract

A motor-operated compressor includes a casing having an inner space including a suction space and a discharge space. A first scroll is disposed in the inner space of the casing. A second scroll is configured to orbit in engagement with the first scroll to form a pair of two compression chambers between the first scroll and the second scroll. A rotary shaft is coupled to the second scroll and configured to transfer a rotational force of a driving motor to the second scroll. An intermediate pressure space is formed on one side of the second scroll and in fluid communication with the discharge space. Oil entering the intermediate pressure space from the discharge space forms back pressure supporting the second scroll toward the first scroll, and a portion of the oil flows into the suction space.

What is claimed is: 
     
         1 . A motor-operated compressor comprising:
 a casing having an inner space composed of a suction space and a discharge space;   a first scroll disposed in the inner space of the casing;   a second scroll configured to orbit in engagement with the first scroll to form a pair of two compression chambers between the first scroll and the second scroll;   a rotary shaft coupled to the second scroll and configured to transfer a rotational force of a driving motor to the second scroll; and   an intermediate pressure space formed on one side of the second scroll in fluid communication with the discharge space, the intermediate pressure space being configured to accommodate oil flowing in from the discharge space to form back pressure supporting the second scroll toward the first scroll, and the intermediate pressure space also being formed in fluid communication with the suction space so that a portion of the accommodated oil flows out into the suction space.   
     
     
         2 . The motor-operated compressor of  claim 1 , further comprising:
 a frame;   the intermediate pressure space being defined between the frame and one surface of the second scroll,   a shaft hole formed in the frame, with the rotary shaft passing through the shaft hole,   a first bearing for radially supporting a first bearing part of the rotary shaft being disposed inside the shaft hole, and   a first radial bearing surface being formed between an inner peripheral surface of the first bearing and an outer peripheral surface of the first bearing part, both ends of the first radial bearing surface being in fluid communication with the intermediate pressure space and the suction space, respectively.   
     
     
         3 . The motor-operated compressor of  claim 2 , further including:
 an oil flow path longitudinally formed in the rotary shaft, the oil flow path having one end in fluid communication with the discharge space; and   at least one oil supply hole extending radially through the rotary shaft from the oil flow path to an outer peripheral surface of the rotary shaft, wherein   the at least one oil supply hole is positioned outside an axial range of the first bearing.   
     
     
         4 . The motor-operated compressor of  claim 3 , wherein the oil flow path includes another end positioned outside an axial range of the first bearing part. 
     
     
         5 . The motor-operated compressor of  claim 2 , further including:
 an oil flow path longitudinally formed in the rotary shaft, the oil flow path having one end in fluid communication with the discharge space; and   a plurality of oil supply holes extending through the rotary shaft from the oil flow path to an outer peripheral surface of the rotary shaft, wherein   at least one of the plurality of oil supply holes is positioned within an axial range of the first bearing part.   
     
     
         6 . The motor-operated compressor of  claim 5 , wherein the at least one oil supply hole positioned within the axial range of the first bearing part has a smaller inner diameter than any of the plurality of oil supply holes positioned outside the axial range of the first bearing part. 
     
     
         7 . The motor-operated compressor of  claim 5 , wherein the at least one oil supply hole positioned within the axial range of the first bearing part is positioned eccentrically toward the discharge space with respect to an axial center of the first bearing part. 
     
     
         8 . The motor-operated compressor of  claim 1 , further including:
 at least one bearing surface formed on an outer peripheral surface of the rotary shaft; and   an oil flow path and an oil supply hole formed in the rotary shaft for guiding the oil of the discharge space to the bearing surface, wherein   the intermediate pressure space is in fluid communication with the discharge space through the oil flow path and the oil supply hole.   
     
     
         9 . The motor-operated compressor of  claim 8 , further including an intermediate pressure hole extending through the second scroll from the intermediate pressure space to the compression chambers. 
     
     
         10 . The motor-operated compressor of  claim 2 , further including:
 a space part forming the intermediate pressure space formed in the frame;   a shaft hole through which the rotary shaft passes formed at a center of the space part; and   a bearing for radially supporting the rotary shaft disposed in the shaft hole, wherein   the intermediate pressure space is in fluid communication with the suction space through a gap defined between an outer peripheral surface of the rotary shaft and an inner peripheral surface of the bearing disposed in the shaft hole.   
     
     
         11 . A motor-operated compressor comprising:
 a casing having an inner space comprising a suction space and a discharge space;   a first scroll disposed in the inner space of the casing;   a second scroll configured to orbit in engagement with the first scroll to form a pair of two compression chambers between the first scroll and the second scroll;   a frame positioned opposite to the first scroll with the second scroll being interposed between the frame and the first scroll;   a rotary shaft having a first bearing part radially supported by the frame, a second bearing part radially supported by the first scroll, and an eccentric part positioned between the first bearing part and the second bearing part and eccentrically coupled to the second scroll; and   an oil flow path having one end in fluid communication with the discharge space formed in the rotary shaft;   at least one oil supply hole formed through the rotary shaft from the oil flow path to an outer peripheral surface of the rotary shaft, the at least one oil supply hole being configured to guide oil from the discharge space to a respective one of the first bearing part, the second bearing part, or the eccentric part,   the at least one oil supply hole comprising:
 a first oil supply hole formed within an axial range of the second bearing part; and 
 a second oil supply hole formed within an axial range of the eccentric part. 
   
     
     
         12 . The motor-operated compressor of  claim 11 , wherein the oil flow path is formed from one end of the rotary shaft forming the second bearing part up to the axial range of the eccentric part. 
     
     
         13 . The motor-operated compressor of  claim 12 , further including:
 a shaft support part protruding opposite to the compression chambers, the shaft support part being formed on the first scroll, the second bearing part of the rotary shaft being rotatably supported by the shaft support part; and   a communication hole for fluid communication between the oil flow path and the discharge space formed in the shaft support part.   
     
     
         14 . The motor-operated compressor of  claim 11 , further including:
 a first radial bearing surface formed between the first bearing part and the frame;   a second radial bearing surface formed between the second bearing part and the first scroll or the casing; and   a third radial bearing surface formed between the eccentric part and the second scroll, wherein   oil passing through the second radial bearing surface or the third radial bearing surface is guided to the first radial bearing surface.   
     
     
         15 . The motor-operated compressor of  claim 14 , wherein the first radial bearing surface has one end in fluid communication with an intermediate pressure space formed between the frame and the second scroll and another end in fluid communication with the suction space.