ROTARY COMPRESSOR

PURPOSE:To reduce the deflection of a main shaft, by forming a reverse U-shaped cut groove, which forms a passage carrying lubricating oil received in the bottom part of an internal wall to its upper part to be again carried to the bottom part thereafter returned directly into the lubricating oil, in the internal wall of a main bearing and enabling the pressure in said groove to be increased. CONSTITUTION:A main bearing 16 has in its internal wall a cut groove 30, and said groove 30, tilting in the direction of rotation of a main shaft 10 from a bottom part of the internal wall, extending to an upper part of the internal wall, again tilting from here in the direction of rotation of the main shaft 10 and extending to the bottom part of the internal wall, forms a reverse U-shaped groove. The bottom part of said internal wall communicates with a flow path 31 in a horizontal part 16a of the main bearing 16, flow path 32 in a cylinder 5 and a flow path 33 in a subbearing. Here compressed high pressure gas, being allowed to flow through a clearance in a compressing mechanism part into a circulative route consisting of lubricating oil 4 impeller pump 8 cut groove 30 flow path 31 flow path 32 flow path 33 lubricating oil 4, holds a high pressure in the circulative route including the cut groove 30. By this pressure, a compressor, continually receiving fixed force by the main shaft 10, enables its deflection to be reduced further a part between the main shaft 10 and the main bearing 16 to be always felled with the lubricating oil.