The present invention generally relates to refrigeration compressors and, more particularly, to such compressors having an orbiting piston member, wherein it is possible to provide an axial and radial compliance force on the orbiting piston member to bias it toward the compressor cylinder walls for proper sealing.
A typical rotary compressor comprises a rotating piston member or roller and a cylinder housing, wherein the rotation of the roller compresses refrigerant fluid. Rotary compressors have advantages over other types of compressors by virtue of their high efficiency, small size, and low cost. Disadvantages of rotary compressors lie in the necessity of close tolerances between the piston and cylinder walls and the high costs of manufacturing parts with such close tolerances.
Scroll compressors employ two opposing involutes one stationary and one orbiting to compress fluid. The sealing mechanism of scroll type compressors includes structures for axial and radial compliance of the scroll members. An advantage of scroll compressors over rotary compressors is that friction between moving parts is decreased since the scrolls are not rotating. Particular disadvantages of scroll compressors are the long machining times for end milling the scroll wraps and the requirement for very close tolerances between the scroll wraps. These requirements make the scrolls very expensive to manufacture. An example of a scroll compressor is found in U.S. Pat. No. 4,875,838 assigned to the assignee of the present invention and incorporated herein by reference.
It is known in the field of compressors to use an orbiting piston member to compress fluid. The disadvantages of these are the complex mechanisms used to create the orbiting motion. In one prior art example of an orbiting piston compressor, it is known to use a conventional Oldham ring assembly to prevent rotation, but there were no means for achieving axial and radial compliance of the orbiting piston within the cylinder housing.
The present invention is directed to overcoming the aforementioned disadvantages wherein it is desired to provide an axial force and radial force upon the orbiting cylindrical piston to facilitate sealing and prevent leakage between the cylindrical piston and cylinder housing.