Gas compressor with buffer spaces

Claim 1

A gas compressor comprising a cylinder, a piston adapted to reciprocate in said cylinder, said piston having a first working surface, a compression space defined between said first working surface and a top surface of said cylinder and having a volume varied with a positional shift of said first working surface when said piston reciprocates to vary pressure of working gas filling in said compression space accordingly, a first buffer space provided below a second working surface of said piston and communicated through a clearance seal between said piston and said cylinder with said compression space, said piston being formed with a blind hole having a top surface acting as a third working surface, a second buffer space provided in said blind hole of said piston and communicated with said first buffer space through a clearance seal, said second buffer space having a volume varied with the positional shift of said third working surface in a reverse direction to that of said compression space, a first connecting circuit for connecting said first buffer space and said compression space and allowing working gas flow in one direction with respect to said compression space and a second connecting circuit for connecting said second buffer space and said compression space and allowing working gas flow in the opposite direction, whereby forces acting on said first, said second and said third working surfaces are set in such a way that, when a reciprocation stroke of said piston is to be lengthened, a shift of a neutral position of the piston reciprocation toward said compression space is prevented and, when the reciprocation stroke is to be shortened, shift of the neutral position away from said compression space is prevented.