Motor-operated compressor

Abstract

A motor-operated compressor includes a casing having a motor chamber that accommodates a driving motor. The compressor also includes a frame. A first scroll having a first spiral wrap is connected to one side of the frame. A second scroll is provided between the frame and the first scroll. The second scroll has a second spiral wrap that engages with the first spiral warp to form compression chambers between the first and second spiral wraps. The compressor also includes a rotation shaft connected at one end to the driving motor and at an opposite end to the second scroll. The compressor includes a back pressure space defined by a balance weight axially separated from a rear surface of the second scroll. A back pressure passage fluidly connects the compression chambers with the back pressure space.

What is claimed is: 
     
         1 . A motor-operated compressor, comprising:
 a casing having a motor chamber;   a frame provided adjacent one end of the motor chamber;   a driving motor positioned on one side of the frame and accommodated in the motor chamber;   a first scroll supported on an opposite side of the frame and having a first spiral wrap;   a second scroll provided between the frame and the first scroll, the second scroll having a second spiral wrap engaged with the first spiral wrap, and forming compression chambers between the first and second wraps while performing an orbiting motion relative to the first scroll by receiving a rotational force of the driving motor;   a rotation shaft having one end connected to a rotor of the driving motor and another end eccentrically coupled to the second scroll to transfer the rotational force of the driving motor to the second scroll;   a balance weight coupled to the rotation shaft, one surface of the balance weight facing a rear surface of the second scroll;   a sealing member provided between the rear surface of the second scroll and the one surface of the balance weight to form a back pressure space between the rear surface of the second scroll and the one surface of the balance weight; and   a back pressure passage extending through the second scroll from the compression chamber to the back pressure space such that the compression chamber and the back pressure space communicate with each other.   
     
     
         2 . The compressor of  claim 1 , wherein the second scroll includes
 a sealing groove having a generally annular shape, the sealing member being slidably insertable in the sealing groove in an axial direction, and   a pressure passage extending through the second scroll from the sealing groove to the compression chamber such that the sealing groove and the compression chamber communicate with each other.   
     
     
         3 . The compressor of  claim 2 , wherein the pressure passage has a length smaller than or equal to a thickness of the second wrap. 
     
     
         4 . The compressor of  claim 3 , wherein
 the first scroll includes a discharge port through which a compressed refrigerant of the compression chamber is discharged, and   the pressure passage communicates with a discharge chamber, or with a compression chamber immediately before the discharge chamber.   
     
     
         5 . The compressor of  claim 4 , wherein the back pressure space has a radial area larger than or equal to a radial area of the compression chamber communicating with the pressure passage. 
     
     
         6 . The compressor of  claim 2 , wherein the back pressure passage communicates with the pressure passage. 
     
     
         7 . The compressor of  claim 6 , wherein the back pressure passage has an inner diameter smaller than or equal to an inner diameter of the pressure passage. 
     
     
         8 . The compressor of  claim 2 , wherein the back pressure passage and the pressure passage are spaced apart from each other. 
     
     
         9 . The compressor of  claim 8 , wherein the back pressure passage and the pressure passage communicate with the same compression chamber. 
     
     
         10 . The compressor of  claim 1 , wherein
 the second scroll includes a generally annular back pressure protrusion portion protruding toward the balance weight,   a sealing groove is provided in the back pressure protrusion portion, the sealing member being slidably inserted in the sealing groove in the axial direction, and   a pressure passage extends through the second scroll at a radially inner position relative to an inner circumferential surface of the back pressure protrusion portion.   
     
     
         11 . The compressor of  claim 1 , wherein the second scroll includes
 a back pressure space groove extending axially into the second scroll, to a predetermined depth, from a surface of the second scroll facing the balance weight,   a sealing groove formed radially outward of the back pressure space groove so that the sealing member is slidably inserted into the sealing groove in the axial direction, and   wherein the back pressure passage extends axially from the back pressure space groove.   
     
     
         12 . The compressor of  claim 1 , wherein the balance weight comprises:
 an eccentric pin portion fixed to the rotation shaft and coupled to the second scroll;   an eccentric mass portion extending from the eccentric pin portion and having a center of gravity eccentrically positioned from a center of the rotation shaft; and   a back pressure surface portion extending radially from the eccentric pin portion to form a back pressure space portion together with the eccentric mass portion.   
     
     
         13 . The compressor of  claim 1 , wherein the frame includes an accommodating space portion for accommodating the balance weight, and the accommodating space portion communicates with the motor chamber. 
     
     
         14 . The compressor of  claim 13 , wherein
 the accommodating space portion includes a generally annular and stepped bearing supporting portion, and   the bearing supporting portion includes a ball bearing for supporting the rotation shaft.   
     
     
         15 . The compressor of  claim 1 , wherein the second scroll incudes
 a boss groove configured to receive the rotation shaft, and   a bush bearing provided between an inner circumferential surface of the boss groove and an outer circumferential surface of the rotation shaft.   
     
     
         16 . The compressor of  claim 1 , wherein
 the casing includes a discharge space accommodating a refrigerant and oil discharged from the compression chamber,   the discharge space includes an oil recollecting passage to guide a refrigerant and oil in the discharge space to a suction side of the compression chamber, and   the oil recollecting passage includes a pressure reducing member.   
     
     
         17 . A motor-operated compressor, comprising:
 a casing including a driving motor;   a frame fixed to the casing;   a first scroll attached to the frame and having a first spiral wrap;   a second scroll positioned between the frame and the first scroll, the second scroll including a second spiral wrap attached to a front surface of the second scroll, the second spiral wrap being engaged with the first spiral wrap, forming at least one compression chamber between the first and second wraps;   a rotation shaft having one end connected to the driving motor and an opposite end eccentrically connected to the second scroll;   a balance weight coupled to the rotation shaft, the balance weight being axially separated from a rear surface of the second scroll to form a back pressure space between the second scroll and the balance weight; and   a back pressure passage extending through the second scroll, the back pressure passage fluidly coupling the at least one compression chamber and the back pressure space.   
     
     
         18 . The compressor of  claim 17 , wherein the second scroll includes:
 a scroll disk, the second spiral wrap protruding from one surface of the scroll disk;   a generally annular sealing groove disposed on an opposite surface of the scroll disk; and   a pressure passage extending from the sealing groove, through the scroll disk, to the compression chamber.   
     
     
         19 . The compressor of  claim 18 , wherein the pressure passage is radially spaced apart from the back pressure passage. 
     
     
         20 . The compressor of  claim 18 , wherein
 the pressure passage is positioned radially outward relative to the back pressure passage, and   the back pressure passage is fluidly coupled to the pressure passage.