Hermetic compressor

Abstract

In a hermetic-type compressor, a piston has a sliding face which slides on an inner wall of the cylindrical hole and is reciprocatably inserted in the cylindrical hole. A connecting rod connects an eccentric shaft part and the piston. The cylindrical hole has a tapered part, whose inside diameter dimension gradually increases from a top dead center of the piston toward a bottom dead center, and an end part on the shaft side. A reciprocation direction of the piston is substantially a horizontal direction. A recessed part, which is recessed to the inside in a radial direction of the piston and holds lubricating oil, is provided in the sliding face of the piston. A part on the lower side in the vertical direction of the piston which comes into contact with the end part on the shaft side of the cylindrical hole when the piston is positioned in the bottom dead center is a part of the sliding face.

1 . A hermetic-type compressor comprising:
 a sealed container storing lubricant oil at its bottom;   an electric mechanism disposed in the sealed container; and   a compression mechanism disposed in the sealed container and driven by the electric mechanism,   wherein the compression mechanism includes:
 a shaft having a main shaft part rotated by the electric mechanism and an eccentric shaft part formed in the main shaft part; 
 a cylinder block having a cylindrical hole constructing a compression chamber and a bearing rotatably supporting the main shaft part, in which the cylindrical hole and the bearing are disposed so that axis of the cylindrical hole and that of the bearing are orthogonal to each other; 
 a piston reciprocatably inserted in the cylindrical hole and having a sliding face which slides on an inner wall of the cylindrical hole; and 
 a connecting rod connecting the eccentric shaft part and the piston, 
   the cylindrical hole has a tapered part, whose inside diameter dimension gradually increases from a top dead center of the piston toward a bottom dead center, and an end part on the shaft side,   a reciprocation direction of the piston is substantially a horizontal direction,   a recessed part, which is recessed to an inside in a radial direction of the piston and holds the lubricating oil, is provided in the sliding face of the piston, and   a part on the lower side in the vertical direction of the piston, which comes into contact with the end part on the shaft side of the cylindrical hole when the piston is positioned in the bottom dead center, is a part of the sliding face.   
     
     
         2 . The hermetic-type compressor according to  claim 1 , wherein the piston has a piston pin hole in a direction orthogonal to axis of the piston,
 the compression mechanism further includes a piston pin inserted in the piston pin hole,   the connecting rod is coupled to the piston pin so as to be rotatable about the axis of the piston pin, and   the sliding face has an extension part which extends from an end part on the connecting rod side toward the recessed part and, when the piston is positioned at the bottom dead center, and the extension part comes into contact with the end part on the shaft side of the cylindrical hole.   
     
     
         3 . The hermetic-type compressor according to  claim 2 , wherein the recessed part is one of a plurality of recessed parts, the plurality of recessed parts include first and second recessed parts formed in positions symmetrical with respect to the axis of the piston extending in the center of the piston pin hole, and
 the first and second recessed parts communicate with each other via the piston pin hole.   
     
     
         4 . The hermetic-type compressor according to  claim 1 , wherein the recessed part has an annular shape extending in an outer periphery direction of the piston. 
     
     
         5 . The hermetic-type compressor according to  claim 4 , wherein the cylindrical hole further includes a straight part provided on the top dead center side of the piston relative to the tapered part and an inflection part as a border between the tapered part and the straight part, and
 the position of the inflection part and the position of the recessed part are set so that when the piston is in a position where lateral pressure load by the piston is maximum, the inflection part is positioned in a range of width in the axis direction of the piston in the recessed part.   
     
     
         6 . The hermetic-type compressor according to  claim 5 , wherein depth of the recessed part is set so that the inflection part is apart from bottom of the recessed part when the piston is in the position where lateral pressure load by the piston is maximum and the inflection part is positioned in the range of width in the axial direction of the piston in the recessed part. 
     
     
         7 . The hermetic-type compressor according to  claim 4 , wherein the recessed part is one of a plurality of recessed parts, the plurality of recessed parts include a first recessed part having an annular shape and a second recessed part having an annular shape positioned on the compression chamber side relative to the first recessed part and extending in the outer periphery direction of the piston, and space volume of the second recessed part is in a range from 0.25 mm 3  to 25 mm 3  (inclusive). 
     
     
         8 . The hermetic-type compressor according to  claim 7 , wherein an interval between the first and second recessed parts is 1 mm or larger. 
     
     
         9 . The hermetic-type compressor according to  claim 1 , wherein the cylindrical hole has a straight part provided on the top dead center side of the piston relative to the tapered part. 
     
     
         10 . The hermetic-type compressor according to  claim 9 , wherein when the piston is positioned at the bottom dead center, an end face on the compression chamber side of the piston is positioned in the tapered part of the cylindrical hole. 
     
     
         11 . The hermetic-type compressor according to  claim 1 , wherein a notch for exposing a part of the recessed part when the piston is positioned in the bottom dead center is provided in an upper part of the end part on the shaft side of the cylindrical hole in the cylinder block. 
     
     
         12 . The hermetic-type compressor according to  claim 1 , wherein a sectional shape of a periphery as the border from the sliding face to the recessed part has an inclination angle of 45° or less with respect to a surface in the axial direction of the piston or an equivalent curved shape.