Cryogenic refrigerator compressor with externally adjustable by-pass/relief valve

摘要

A cryogenic refrigeration compressor which has externally adjustable in-line pressure relief valve positioned between a helium supply line and the helium return line. The valve has coaxial inlet and outlet members (46, 42) and an externally adjustable spring compression spring compression member (44), which together they define a duct (48), within which is a poppet valve (76), and a spring (64) which exerts bias against the valve to close the valve against fluid pressures. The spring (64) is compressed by rotation of the compression member (44) to vary the bias on the poppet valve (44).