Abstract: A scroll machine utilizes a floating seal to isolate pressurized fluid to provide axial biasing. The floating seal is designed as a single piece plate with inner and outer annular seals. The inner and outer annular seals can be U-shaped, V-shaped or L-shaped and each configuration is oriented to provide pressure actuation of the seal. Additional embodiments add a discharge valve, a high temperature protection system or a high pressure protection system to the floating seal.

Abstract: A scroll-type refrigeration compressor is disclosed which incorporates an efficient, reliable, low cost modulation system employing a single actuator to effect switching between full and reduced capacity operation. The modulation system of the present invention includes an annular valving ring rotationally supported on the non-orbiting scroll which operates to ensure simultaneous opening and closing one or more unloading passages thus avoiding the possibility of even transient pressure imbalances between opposed compression pockets during operation of the compressor or in one of the alternative embodiments, providing a controlled imbalance to provide a noise reducing torsional loading on the Oldham coupling. Further, the modulation system of the present invention provides for reduced capacity at both start up and shut down thus enabling the use of more efficient lower starting torque motors and reducing the potential for noise generating reverse rotation on shut down.