Hermetic reciprocating compressor with thrust ball bearing

Abstract

A hermetic compressor includes a hermetic container that stores lubricating oil, an electrically-driven element having a stator and a rotor, a shaft having a compressing element driven by the electrically-driven element, and including an eccentric shaft portion, a cylinder block, a piston, a coupling device that connects the piston and the eccentric shaft portion, a main bearing, and a thrust ball bearing that supports a vertical load by the self weight of the rotor and the shaft. The thrust ball bearing includes a plurality of balls having a diameter of 3 mm or less, a holder portion holding the balls and formed of a polymeric material, and an upper washer and a lower washer disposed above and below the balls, respectively, and the viscosity grade of the lubricating oil is from ISO VG3 to ISO VG10.

1 . A hermetic compressor comprising:
 a hermetic container that stores lubricating oil;   an electrically-driven element including a stator and a rotor;   a shaft having a compressing element driven by the electrically-driven element, and including a main shaft, to which the rotor is fixed, and an eccentric shaft portion formed via a flange portion;   a cylinder block including a cylindrical compression chamber;   a piston that reciprocates within the compression chamber;   a coupling device that connects the piston and the eccentric shaft portion;   a main bearing that is formed at the cylinder block to journal the main shaft portion of the shaft; and   a thrust ball bearing that supports a vertical load by self-weight of the rotor and the shaft,   wherein the thrust ball bearing includes
 a plurality of balls having a diameter of 3 mm or less, 
 a holder portion holding the balls and formed of a polymeric material, and 
 an upper washer and a lower washer disposed above and below the balls, respectively, and 
   viscosity grade of the lubricating oil is from ISO VG3 to ISO VG10.   
   
   
       2 . The hermetic compressor of  claim 1 ,
 wherein the holder portions is provided with a plurality of pocket portions holding the balls, an inner surface of the pocket portion is formed so as to have a radius of curvature that is less than a radius of curvature of the ball, and the ball and the holder portion come into annular line contact with each other at the edge of the pocket portion.   
   
   
       3 . The hermetic compressor of  claim 1 , further comprising:
 an oil supply passage that allows an upper portion of the holder portion and an inner surface of the pocket portion to directly communicate with each other.   
   
   
       4 . The hermetic compressor of  claim 1 ,
 wherein the compressing element is disposed above the electrically-driven element, and the thrust ball bearing is disposed between the flange portion and an upper end surface of the main bearing.   
   
   
       5 . The hermetic compressor of  claim 1 ,
 wherein the electrically-driven element is driven at a plurality of operation frequencies by an inverter, and the rotor rotates at a rotational frequency of at least 60 Hz or more.