Patent ID: 8454333

Claim:
A rotary fluid machine, comprising: a cylinder with an annular cylinder chamber; an annular piston disposed in the cylinder chamber so as to be eccentric to the cylinder, the annular piston dividing the cylinder chamber into an outer cylinder chamber and an inner cylinder chamber, an outer surface of the piston defining an inner periphery of the outer cylinder chamber and an inner surface of the piston defining an outer periphery of the inner cylinder chamber; and a blade arranged in the cylinder chambers to divide each of the outer and inner cylinder chambers into a high-pressure chamber and a low-pressure chamber, the cylinder and the piston being arranged to eccentrically move relative to each other, a height of the outer cylinder chamber is different from a height of the inner cylinder chamber as measured in a direction of a rotational axis of the rotary fluid machine, and the annular piston extending axially from an end plate to a common axial location on the inner and outer surfaces thereof defining outer and inner peripheries of the inner and outer cylinder chambers, and the end plate having different axial thicknesses radially outward and inward of the annular piston to define the different heights of the outer and inner cylinder chambers.