Miniature cryogenic cooling system with split-phase dual compressor and phase-shifting device

Claim 1

In a miniature cryogenic system having two compressors with two outlets, first and second conduits carrying a working fluid, each conduit connected to one of the outlets, said working fluid pressurized in a split-phase relationship by said compressors, wherein the improvement comprises a cold finger assembly including: an elongate housing having a cryogenically cooled end and an internal abutment dividing said housing into first and second interior compartments, said first compartment extending from said cooled end to said abutment; a displacer disposed slidingly within said first compartment for longitudinal reciprocating motion therein and creating a first working volume between said cooled end and said displacer and creating a second working volume between said displacer and said abutment; a first regenerative bed disposed within said displacer; a first inlet means located in said housing adapted for providing fluid communication between said first conduit and said first interior compartment; first and second port means in said displacer providing fluid communication through said first regenerative bed between said first inlet means and said first working volume; a second regenerative bed disposed within said second interior compartment; a second inlet means in said housing providing fluid communication through said second regenerative bed between said second conduit means and said second working volume; and means to develop transient cushioning overpressures in said first and second working volumes as said displacer reciprocates alternately toward said cooled end and toward said abutment under the push-pull influence of said split-phase working fluid flow from said compressors whereby cooling is effected in said first and in said second working volumes.