Patent ID: 7435065

Claim:
A rotary fluid machine comprising: an eccentric rotary piston mechanism including a cylinder having an annular cylinder chamber, an annular piston housed in an eccentric fashion relative to the cylinder in the cylinder chamber and dividing the cylinder chamber into an outer cylinder chamber and an inner cylinder chamber, and a blade disposed in the cylinder chamber and dividing each of the outer and inner cylinder chambers into a first chamber and a second chamber, the cylinder and the annular piston relatively executing eccentric rotary motion; a driving mechanism for driving the eccentric rotary piston mechanism; a casing configured to house the eccentric rotary piston mechanism; and the cylinder being provided with the blade; a coupling member by which the annular piston and the blade are mutually movably coupled together, the coupling member having a first sliding surface against the annular piston and a second sliding surface against the blade, the annular piston being formed into a C-shape with a split and having inner and outer annular peripheral surfaces with an annular midline equally radially spaced therebetween relative to a center rotation axis of the driving mechanism, the blade being configured to be inserted through the split of the annular piston so that the blade extends from an inner peripheral wall surface to an outer peripheral wall surface of the annular cylinder chamber, the coupling member being formed by a swinging bushing having a blade groove that advanceably and withdrawably holds the blade and a circular arc-shaped outer peripheral surface that is swingably held in the split by the annular piston, and a swing center of the swinging bushing being disposed more radially inwardly of the annular midline than the annular piston relative to the center rotation axis of the driving mechanism.