Machine with rotary piston including a flexible annular member

In a fluid-flow machine

• means defining a cylinder having an internal cylidrical surface and ports in that surface respectively for the admission and exhaust of fluid,
• an assembly mounted within the cylinder including
• two opposed, interconnected, parts, together rotatable relatively to the cylinder, each part having a peripheral surface with complementary curvature to that of the internal cylindrical surface of the cylinder and having the same centre as that of the cylinder,
• means biasing the said parts towards the cylinder wall, and
• a flexible ring interposed between the opposed parts and the said internal cylindrical surface and being pressed against said surface by the parts so that rotation of the parts causes non-slip relative motion between the ring and said surface, working space for the fluid being defined between the ring and said surface, and
• means mounted on the cylinder dividing the working space into a fluid suction chamber and a fluid compression chamber,
• the peripheral surface of each said part of the assembly being such that as the ring moves into contact with the portion of the internal peripheral surface of the cylinder defining the ports, surface to surface contact is maintained.