Multi-stage cryogenic engine

Claim 1

IN A MULTI-STAGE CRYOGENIC ENGINE FOR PROVIDING REFRIGERATION AT LOW TEMPERATURES AND OPERATING WITH PARALLEL PISTONS ON A MODIFIED STIRLING CYCLE, WHEREIN A MOTOR DRIVES A CRANKSHAFT ROTATING CRANKS TO WHICH ARE ATTACHED CONNECTING RODS DISPOSED AT APPROXIMATELY 90* WITH RESPECT TO EACH OTHER, AND OPERATING ON A WORKING GAS UNDER PRESSURE IN A SEALED CRANK CASE, THE IMPROVEMENT COMPRISING, A COMPRESSOR PISTON CONNECTED TO A CONNECTING ROD, AND A COMPRESSOR CYLINDER IN WHICH SAID PISTON IS DESIGNED TO RECIPROCATE, SAID CYLINDER TERMINATING IN A HEAD, AN EXPANDER PISTON CONNECTED TO ANOTHER CONNECTING ROD, AND AN EXPANDER CYLINDER IN WHICH SAID LATTER PISTON IS DESIGNED TO RECIPROCATE, A GAS-PERMEABLE HEAT EXCHANGER DISPOSED ABOVE SAID COMPRESSOR CYLINDER HEAD AND DESIGNED TO TRANSFER COMPRESSION HEAT FROM COMPRESSED GAS TO A COOLING MEANS, AN EXPANDER PISTON EXTENSION OF LOW THERMAL CONDUCTIVITY ATTACHED TO SAID EXPANDER PISTON IN AXIAL RELATION THEREWITH AND EXTENDING BEYOND THE EXPANDER CYLINDER, SAID PISTON EXTENSION BEING STEPPED SO THAT IT IS OF TWO DIFFERENT DIAMETERS, THE LOWER PART THEREOF HAVING APPROXIMATELY THE DIAMETER OF SAID EXPANDER PISTON AND THE UPPER PART THEREOF HAVING A SMALLER DIAMETER, A FIRST EXTENSION OF SAID EXPANDER CYLINDER COMPRISING A TUBE OF LOW THERMAL CONDUCTIVITY CONNECTED AT ONE END TO THE TOP OF SAID EXPANDER CYLINDER AND SURROUNDING AT LEAST A PORTION OF THE LOWER PART OF SAID EXPANDER PISTON EXTENSION, A FIRST COLD HEAT OF HIGH THERMAL CONDUCTIVITY CONNECTED TO THE OTHER END OF SAID TUBE IN A MANNER SUCH AS TO FORM A FIRST EXPANDER VOLUME BETWEEN SAID FIRST COLD HEAD AND THE TOP OF THE SAID LOWER PART OF SAID EXPANDER PISTON EXTENSION, AND HAVING A CONDUIT THEREIN DESIGNED TO PERMIT FLOW OF WORKING GAS INTO AND OUT OF SAID FIRST EXPANDER VOLUME AND TO PERMIT HEAT TRANSFER BETWEEN WORKING GAS AND SAID FIRST COLD HEAD, AND HAVING A CENTRAL OPENING DESIGNED TO PERMIT THE SAID UPPER PART OF SAID EXPANDER PISTON EXTENSION TO RECIPROCATE THERETHROUGH, A FIRST REGENERATOR DISPOSED ABOVE SAID GAS PERMEABLE HEAT EXCHANGER AND HAVING ONE END CONNECTED THEREWITH TO ALLOW WORKING GAS THEREFROM TO FLOW THERETHROUGH AND THE OTHER END CONNECTED WITH SAID CONDUIT IN SAID FIRST COLD HEAD FOR FLOW OF GAS THERETHROUGH AND DESIGNED ALTERNATINGLY TO ABSORB HEAT AND REJECT HEAT FROM WORKING GAS FLOWING ALTERNATELY THERETHROUGH, A SECOND EXTENSION OF SAID EXPANDER CYLINDER COMPRISING A TUBE OF LOW THERMAL CONDUCTIVITY, CONNECTED AT ONE END TO SAID FIRST COLD HEAD AND SURROUNDING THE UPPER PART OF SAID EXPANDER PISTON EXTENSION, A SECOND COLD HEAD OF HIGH THERMAL CONDUCTIVITY SERVING AS THE COLDEST PART OF SAID ENGINE AND CONNECTING TO THE OTHER END OF SAID SECOND EXTENSION OF SAID EXPANDER CYLINDER IN A MANER SUCH AS TO FORM A SECOND EXPANDER VOLUME BETWEEN SAID SECOND COLD HEAD AND THE TOP OF SAID UPPER PORTION OF SAID EXPANDER PISTON EXTENSION, AND HAVING A CONDUIT THEREIN DESIGNED TO PERMIT FLOW OF WORKING GAS INTO AND OUT OF SAID SECOND EXPANDER VOLUME AND TO PERMIT HEAT TRANSFER BETWEEN WORKING GAS AND SAID SECOND COLD HEAD, A SECOND REGENERATOR DISPOSED ABOVE SAID FIRST COLD HEAD AND HAVING ONE END CONNECTED PNEUMATICALLY TO THE JUNCTION BETWEEN THE SAID FIRST REGENERATOR AND SAID CONDUIT IN SAID FIRST COLD HEAD, AND THE OTHER END CONNECTED WITH SAID CONDUIT IN SAID SECOND COLD HEAD, WHEREBY WORKING GAS IS PERMITTED TO FLOW THROUGH SAID SECOND REGENERATOR AND INTO AND OUT OF SAID SECOND EXPANDER VOLUME, AND AN INSULATING MEANS DESIGNED TO INSULATE THERMALLY ALL PARTS OF THE ENGINE WHICH ARE MAINTAINED AT TEMPERATURES BELOW THOSE OF THE COMPRESSOR AND EXPANDER CYLINDERS.