Reciprocating compressor and refrigerating machine having the same

Abstract

Disclosed are a reciprocating compressor and a refrigerating apparatus having the same, wherein a magnet bearing is inserted between facing surfaces between a cylinder block and a crank shaft and the magnet bearing so as to generate a magnetic force both in a shaft direction and in a radial direction, so that the cylinder block and the crank shaft can be supported both in the shaft direction and in the radial direction, thereby reducing a frictional loss due to an eccentric load of the crank shaft, and also, both magnets are disposed to overlap each other so as to prevent an increase in an input load due to the magnetic force between the magnets, resulting in further improvement of energy efficiency of the compressor.

1 . A reciprocating compressor comprising:
 a casing having a hermetic inner space;   a driving motor installed in the inner space of the casing;   a cylinder block installed in the inner space of the casing together with the driving motor, and having a cylinder at one side thereof, a shaft accommodation hole forming a journal bearing surface being formed at one side of the cylinder;   a crank shaft including a shaft portion coupled to a rotor of the driving motor and inserted into the shaft accommodation hole of the cylinder block, and a plate-shaped extending portion extending from an outer circumferential surface of the shaft portion to be formed wider than the shaft accommodation hole of the cylinder block; and   a magnet bearing disposed between the cylinder block and the crank shaft to allow generation of a force in a shaft direction and a force in a radial direction so that the crank shaft is supported with respect to the cylinder block in a shaft direction and in a radial direction.   
     
     
         2 . The compressor of  claim 1 , wherein the magnet bearing comprises a first magnet installed at the cylinder block, and a second magnet installed at the crank shaft or the rotor of the driving motor, to which the crank shaft is coupled, to conform with the first magnet,
 wherein the section of the first magnet and the section of the second magnet are disposed so that centers thereof in the shaft direction have a predetermined interval therebetween.   
     
     
         3 . The compressor of  claim 1 , wherein the magnet bearing comprises a first magnet installed at the cylinder block, and a second magnet installed at the crank shaft or the rotor of the driving motor, to which the crank shaft is coupled, to conform with the first magnet,
 wherein the first magnet and the second magnet are disposed to overlap each other in the shaft direction.   
     
     
         4 . The compressor of  claim 3 , wherein each of the first magnet and the second magnet is formed in an annular shape, and an outer diameter of one magnet is smaller than another magnet. 
     
     
         5 . The compressor of  claim 3 , wherein an overlapped height between the first and second magnets is adjusted by an interval between a thrust surface of the cylinder block and a thrust surface of the crank shaft. 
     
     
         6 . The compressor of  claim 1 , wherein a magnet insertion groove in which the first magnet or the second magnet is inserted is formed at least one of the thrust surface of the cylinder block or the corresponding thrust surface of the crank shaft. 
     
     
         7 . The compressor of  claim 5 , wherein the magnet insertion groove is not deeper than the height of the magnet in the shaft direction, the magnet being inserted into the magnet insertion groove. 
     
     
         8 . The compressor of  claim 1 , wherein the magnet bearing comprises a first magnet installed at the cylinder block and a second magnet installed at the crank shaft to conform with the first magnet,
 wherein a bearing supporting portion protruded from a periphery of the shaft accommodation hole of the cylinder block by a predetermined height so that an upper surface thereof forms a thrust surface, an inner circumferential surface of the first magnet coming in contact with an outer circumferential surface of the bearing supporting portion.   
     
     
         9 . The compressor of  claim 8 , wherein the thrust surface of the bearing supporting portion is not lower than an upper surface of the first magnet. 
     
     
         10 . The compressor of  claim 8 , wherein a magnet insertion groove in which the second magnet is inserted is formed at the thrust surface of the plate-shaped extending portion of the crank shaft, the magnet insertion groove being deep enough that the second magnet overlaps the first magnet in the shaft direction. 
     
     
         11 . The compressor of  claim 1 , wherein the magnet bearing comprises a first magnet installed at the cylinder block, and a second magnet installed at the crank shaft or the rotor of the driving motor, to which the crank shaft is coupled, to conform with the first magnet,
 wherein the first magnet and the second magnet are magnetized so that polarities thereof are symmetrical in the shaft direction.   
     
     
         12 . The compressor of  claim 11 , wherein the first magnet and the second magnet are disposed to locate the same polarity in the radial direction when the thrust surface of the cylinder block comes in contact with the thrust surface of the crank shaft. 
     
     
         13 . The compressor of  claim 1 , wherein the magnet bearing comprises a first magnet installed at the cylinder block, and a second magnet installed at the crank shaft or the rotor of the driving motor, to which the crank shaft is coupled, to conform with the first magnet,
 wherein the first magnet and the second magnet are formed in a shape having a rectangular or perfect square section.   
     
     
         14 . The compressor of  claim 1 , wherein the magnet bearing comprises a first magnet installed at the cylinder block, and a second magnet installed at the crank shaft or the rotor of the driving motor, to which the crank shaft is coupled, to conform with the first magnet,
 wherein the first magnet and the second magnet are inclined so that facing surfaces thereof in the shaft direction are symmetrical about each other in the shaft direction.   
     
     
         15 . A refrigerating apparatus comprising:
 a compressor;   a condenser connected to a discharge side of the compressor;   an expansion apparatus connected to the condenser; and   an evaporator connected to the expansion apparatus and to a suction side of the compressor,   wherein the compressor is a compressor according to  claim 1 .