Piston reciprocating mechanism, pump, compressor, and vacuum pump

摘要

This piston reciprocating mechanism reciprocates a piston (2) in a cylinder (1) by converting, to reciprocating motion in a straight line indicating the moving direction of the piston (2) placed in the cylinder (1), rotating motion of a rotor (5) placed so as to have a shaft center on the straight line. The mechanism is characterized by including: rollers (3a), (3b) placed on respective side surfaces of the rotor (5); a housing part (2a) which is formed at the rotor (5) side of the piston (2) and which houses the rotor (5); and a cam groove (2c) which is formed to have a wave shape circling and oscillating in the straight line direction on the inner circumferential surface of the housing part (2a) facing the rotor (5), which houses therein the rollers (3a), (3b), and which causes, in association with rotation of the rotor (5), the piston (2) to reciprocate in the straight line when the piston (2) makes a rotational contact with the rollers (3a), (3b) and oscillates along the wave shape when receiving force from the rollers (3a), (3b).