Refrigerant compressor and refrigeration apparatus using the same

Abstract

In a refrigerant compressor including a sealed container in which refrigerating machine oil is stored, a shaft part that includes a main shaft and an eccentric shaft, or a bearing part that includes a main bearing and an eccentric bearing, is provided with tapered portions, the tapered portions being respectively formed on one end side and another end side of the shaft part or the bearing part in an axial direction of the bearing part such that a diameter of the shaft part or the bearing part changes from an outer side toward a central side in a longitudinal direction of a crankshaft, each tapered portion allowing the shaft part and the bearing part to come into line contact with each other in a state where an axis of the shaft part is tilted relative to an axis of the bearing part. A ratio C/D, which is a ratio of a clearance C between the shaft part and the bearing part to a diameter D of the shaft part, is set to a value within a range of not less than 4.0×10 −4 and not greater than 3.0×10 −3 . A taper depth dB of each tapered portion is set to a value not less than 2.0×10 −3 mm. In a combination of the shaft part and the bearing part corresponding thereto, a ratio G/D, which is a ratio of a maximum gap G to the diameter D of the shaft part, is set to a value not greater than 4.0×10 −3 . The maximum gap G is a sum of the clearance C and a total value of the taper depths d B .

1 . A refrigerant compressor comprising:
 a sealed container in which refrigerating machine oil is stored;   an electric element accommodated in the sealed container and driven by electric power supplied from outside; and   a compression element accommodated in the sealed container and covered with the refrigerating machine oil, the compression element being driven by the electric element to compress refrigerant gas supplied from outside, wherein   the compression element includes:
 a crankshaft including a main shaft and an eccentric shaft that are arranged side by side in a longitudinal direction; 
 a main bearing that pivotally supports the main shaft; and 
 an eccentric bearing that pivotally supports the eccentric shaft, 
   a shaft part that is at least one of the main shaft and the eccentric shaft, or a bearing part that is at least one of the main bearing and the eccentric bearing, is provided with a tapered portion, the tapered portion being formed on at least one of one end side and another end side of the shaft part or the bearing part in an axial direction of the bearing part such that a diameter of the shaft part or the bearing part changes from an outer side toward a central side in the longitudinal direction of the crankshaft, the tapered portion allowing the shaft part and the bearing part to come into line contact with each other in a state where an axis of the shaft part is tilted relative to an axis of the bearing part,   a ratio C/D, which is a ratio of a clearance C between the shaft part and the bearing part to a diameter D of the shaft part, is set to a value within a range of not less than 4.0×10 −4  and not greater than 3.0×10 −3 ,   a taper depth d B , which corresponds to a distance between one end and another end of the tapered portion in the axial direction of the bearing part, the distance being in a direction perpendicular to the axis of the bearing part, is set to a value not less than 2.0×10 −3  mm, and   in a combination of the shaft part and the bearing part corresponding thereto, a ratio G/D, which is a ratio of a maximum gap G to the diameter D of the shaft part, is set to a value not greater than 4.0×10 −3 , the maximum gap G being a sum of the clearance C and a total value of the taper depth d B  of the tapered portion.   
     
     
         2 . The refrigerant compressor according to  claim 1 , wherein
 the shaft part or the bearing part is provided with a pair of the tapered portions that are formed on both sides of the shaft part or the bearing part in the axial direction of the bearing part, and   the following elements satisfy Math. 1 and Math. 2:
 a taper depth d BU , which is the taper depth d B  of the tapered portion on the one end side of the shaft part or the bearing part in the axial direction of the bearing part; 
 a taper width W BU , which is a width, in the axial direction of the bearing part, of the tapered portion on the one end side of the shaft part or the bearing part in the axial direction of the bearing part; 
 a taper depth d BL , which is the taper depth d B  of the tapered portion on the other end side of the shaft part or the bearing part in the axial direction of the bearing part; 
 a taper width W BL , which is a width, in the axial direction of the bearing part, of the tapered portion on the other end side of the shaft part or the bearing part in the axial direction of the bearing part; 
 a bearing length B of the bearing part; and 
 the clearance C, where 
 Math. 1 is d BU /W BU ≤(C+d BU +d BL )/B, 
 Math. 2 is d BL /W BL ≤(C+d BU +d BL )/B. 
   
     
     
         3 . The refrigerant compressor according to  claim 2 , wherein
 of the shaft part or the bearing part, an opposite-to-taper surface that faces an opposite surface of the tapered portion on the one end side in the axial direction of the bearing part is provided with a first sliding surface formed thereon,   of the shaft part or the bearing part, an opposite-to-taper surface that faces an opposite surface of the tapered portion on the other end side in the axial direction of the bearing part is provided with a second sliding surface formed thereon, and   a sliding width L 1  of the first sliding surface facing the opposite surface of the tapered portion on the one end side is less than the taper width W BU , and a sliding width L 2  of the second sliding surface facing the opposite surface of the tapered portion on the other end side is less than the taper width W BL , when seen in a direction perpendicular to the axis of the opposite shaft part or bearing part.   
     
     
         4 . The refrigerant compressor according to  claim 1 , wherein
 at least one of the shaft part and the bearing part is provided with a pair of the tapered portions that are formed on both sides of the at least one of the shaft part and the bearing part in the axial direction of the bearing part, and   at least one of the shaft part and the bearing part includes a small-diameter portion that has a less diameter than a maximum diameter of the tapered portions.   
     
     
         5 . The refrigerant compressor according to  claim 1 , wherein
 the tapered portion has a linear or continuously curved surface when seen in a direction perpendicular to an axis of the tapered portion.   
     
     
         6 . The refrigerant compressor according to  claim 1 , wherein
 the shaft part includes a coating formed on its surface portion that slides on the bearing part, and   a hardness of the coating is higher than or equal to a hardness of a surface of the bearing part, the surface facing the coating.   
     
     
         7 . The refrigerant compressor according to  claim 1 , wherein
 the electric element is inverter-driven at a plurality of operating frequencies.   
     
     
         8 . A refrigeration apparatus comprising a refrigerant circuit including:
 the refrigerant compressor according to  claim 1 ;   a radiator that radiates heat of a refrigerant;   a decompressor that decompresses the refrigerant; and   a heat absorber that absorbs the heat of the refrigerant, wherein   in the refrigerant circuit, the refrigerant compressor, the radiator, the decompressor, and the heat absorber are connected by piping in an annular manner.