OIL-FREE COMPRESSOR

PURPOSE:To make ventilation and cooling of a crank chamber effectively by providing the crank chamber at its wall with a flowout hole and a suction hole in communication with the inside and outside of the crank chamber, and equipping these holes with nozzles embodied in respective specified shapes and protruding in specific directions. CONSTITUTION:A piston 6 in a cylinder 2 of this compressor concerned 1 is coupled with one end of a connecting rod 8 by a coupling pin 7. The other end of the connecting rod 8 is coupled with the crank part 14 of a crank shaft 10 situated in a crank chamber 3. This crank shaft 10 is equipped with a balance weight 16. The wall surface of the crank chamber 3 intersecting the tangential to the rotational locus of this balance weight 16 is provided with a flowout hole 18 and a suction hole 19 having respective nozzles 18a, 19a with their flow path section areas decreasing gradually toward ahead of the rotating direction of the balance weight 16. The nozzle 18a at the flowout hole side is protruded outward while the one 19a on the suction hole side protrudes inwards.