Patent ID: 7654096

Claim:
In a GM, Solvay, or GM type pulse tube refrigerator, a valve assembly comprising: a motor driven rotating valve disc which is restrained from moving axially; a non-rotating valve seat which can move axially, wherein different pressures exerted against at least two surfaces of the valve seat result in a net force such that the rotating valve disc is forced in a direction toward the valve motor; a first of the at least two surfaces of the valve seat is in a central cavity in the valve seat, the cavity being connected to system high-pressure gas; a second of the at least two surfaces of the valve seat is in the annular area between the central cavity in the valve seat and the outside of the valve seat where the second surface is connected to one of system low-pressure gas or gas at a pressure between the system high pressure and vacuum; and both first and second of the at least two surfaces are distal to the face of the valve disc.