Hermetic compressor

Abstract

A hermetic compressor stores oil ( 106 ), and houses compression mechanism ( 105 ) that compresses a refrigerant gas, in housing ( 101 ). Piston ( 140 ) is formed with at least two grooves ( 144 ) that do not include the edges of top surface ( 142 ) and skirt surface ( 143 ), on outer circumferential surface ( 145 ) of the piston, where groove ( 144 ) communicates with the space in housing ( 101 ), at least near the bottom dead center. Such a makeup allows the sliding part to be supplied with oil through groove ( 144 ), increasing efficiency owing to high sealability and a low sliding loss.

1 . A hermetic compressor comprising: 
 a compression mechanism including: 
 a crankshaft allocated vertically, having a main axis part and an eccentric axis part;  
 a cylinder;  
 a piston that moves reciprocally in the cylinder, and includes a top surface and a skirt surface, both vertical to a direction of the reciprocal movement, and an outer circumferential surface parallel with a direction of the reciprocal movement;  
 a connector that connects the eccentric axis part and the piston; and  
 an oil supplying structure for supplying an outer surface of the piston with oil,  
   wherein the piston has at least two grooves on an outer circumferential surface thereof, the grooves are independent each other and formed on a part of the circumferential surface, excluding an edge of the top surface and an edge of the skirt surface, and the grooves communicate with a space in the housing, when the piston is positioned at a bottom dead center;    an electromotive element, and    a housing containing the compression mechanism and the electromotive element.    
     
     
         2 . A hermetic compressor as claimed in  claim 1 , wherein the groove can store the oil therein.  
     
     
         3 . A hermetic compressor as claimed in  claim 1 , wherein an area of the grooves is not less than half an area of the outer circumferential surface of the piston.  
     
     
         4 . A hermetic compressor as claimed in  claim 1 , 
 wherein the crankshaft further includes a secondary axis part coaxially with a main axis part, and the eccentric part is sandwiched by the secondary axis part and the main axis part, and    the compressor further includes a secondary bearing pivotally supporting the secondary axis part.    
     
     
         5 . A hermetic compressor as claimed in  claim 1 , wherein a shape of an edge on the skirt side of the groove includes a shape that does not form a line parallel with the skirt surface, in a case where the outer circumferential surface of the piston is developed on a plane.  
     
     
         6 . A hermetic compressor as claimed in  claim 5 , wherein the shape of the edge on the skirt side of the groove includes a curve having a predetermined curvature.  
     
     
         7 . A hermetic compressor as claimed in  claim 1 , wherein the electromotive element is inverter-driven at a plurality of operation frequencies including at least power-line frequency or lower.  
     
     
         8 . A hermetic compressor as claimed in  claim 1 , wherein the compression mechanism compresses a refrigerant gas, and the refrigerant gas is R600a.  
     
     
         9 . A hermetic compressor as claimed in  claim 1 , wherein the oil is selected from ISO viscosity grades from VG10 to VG5, both included.