Hermetic compressor

Abstract

A hermetic compressor includes a hermetic container, a motor element, and a compression element. A shaft of the compression element includes a main shaft, a flange projecting from the main shaft, and an eccentric shaft connected to the flange. A main bearing has a thrust surface contacting and sliding on the flange of the shaft. The thrust surface consists of a first portion and a second portion. The first portion is farther from the compression chamber than the center axis is. The second portion is closer to the compression chamber than the center axis is. The area of the first portion is larger than the area of the second portion. This hermetic compressor has a high efficiency and a high reliability.

1 . A hermetic compressor comprising:
 a hermetic container;   a motor element disposed in the hermetic container, the motor element including a stator and a rotor; and   a compression element disposed in the hermetic container, the compression element being driven by the motor element,   wherein the compression element includes:
 a shaft including a main shaft extending along a center axis, a flange projecting from the main shaft, and an eccentric shaft connected to the flange, wherein the shaft has the rotor fixed thereto, 
 a cylinder block having a compression chamber located from the center axis of the main shaft in a first direction perpendicular to the center axis; 
 a piston reciprocating in the compression chamber in the first direction and a second direction opposite to the first direction; 
 a connection mechanism connecting the piston and the eccentric shaft; and 
 a main bearing having an axial hole supporting the main shaft of the shaft, the main bearing having a thrust surface surrounding the axial hole, the thrust surface contacting and sliding on the flange of the shaft, 
   wherein the thrust surface consists of a first portion and a second portion, the first portion being farther from the compression chamber than the center axis is in a direction parallel to the first direction, the second portion being closer to the compression chamber than the center axis is in the direction parallel to the first direction, and   wherein an area of the first portion is larger than an area of the second portion.   
     
     
         2 . The hermetic compressor of  claim 1 , wherein the thrust surface supports a force in a vertical direction and a component of a repulsive force in the vertical direction, the force in the vertical direction being generated due to own weights of the rotor and the shaft, the repulsive force being generated due to a compression by the piston. 
     
     
         3 . The hermetic compressor of  claim 1 ,
 wherein the hermetic container is configured to store lubricating oil; and   wherein the thrust surface has an oil groove communicating with the axial hole, the oil groove allowing the lubricating oil to pass through the oil groove.   
     
     
         4 . The hermetic compressor of  claim 3 , wherein the oil groove is formed in the second portion of the thrust surface. 
     
     
         5 . The hermetic compressor of  claim 4 , wherein the oil groove extends along a straight line extending from the center axis in the first direction. 
     
     
         6 . The hermetic compressor of  claim 1 ,
 wherein the main shaft of the shaft extends from the flange in a third direction perpendicular to the first direction; and   wherein the thrust surface inclines in the third direction along the second direction.   
     
     
         7 . The hermetic compressor of  claim 1 , wherein the thrust surface has a nitriding treatment and a ceramic coating treatment performed thereto. 
     
     
         8 . The hermetic compressor of  claim 1 , wherein the main bearing includes:
 a radial bearing having the axial hole; and   a thrust bearing having the thrust surface, the thrust bearing being a separate component from the radial bearing.   
     
     
         9 . The hermetic compressor of  claim 1 ,
 wherein the main shaft of the shaft extends from the flange to a third direction perpendicular to the first direction; and   wherein the rotor of the motor element has a magnetic center displaced in the third direction from a magnetic center of the stator.   
     
     
         10 . The hermetic compressor of  claim 9 , wherein the magnetic center of the rotor is positioned under the magnetic center of the stator.