Scavenging flow circuit for stirling cycle engine

Claim 1

A STIRLING CYCLE ENGINE, COMPRISING: (A) A HOT ZONE; AND (B) A COLD ZONE; (C) A GAS FLOW CIRCUIT BETWEEN SAID HOT ZONE AND SAID COLD ZONE, SAID CIRCUIT INCLUDING, A REGENERATOR; AND (D) AT LEAST ONE ADDITIONAL CLOSED LOOP GAS CIRCUIT, SAID ADDITIONAL CIRCUIT INCLUDING AN INLET AND AN OUTLET TO THE ZONE AND AN EXTERIOR HEAT EXCHANGER AND MEANS TO RECIRCULATE THE GAS CHARGE THROUGH SAID CLOSED LOOP GAS CIRCUIT AND SAID ADDITIONAL CIRCUIT ARRANGED TO SCAVENGE AT LEAST ONE OF SAID ZONES IN SUCH A MANNER THAT AT LEAST PART OF THE ZONE GAS CHARGE IS REPLACED BY THE SCAVENGE GAS CHARGE AT LEAST ONCE EACH CYCLE; (E) MEANS TO HEAT A SCAVENGE GAS CHARGE IN SAID ADDITIONAL CIRCUIT BEFORE SAID CHARGE ENTERS SAID HOT ZONE TO A TEMPERATURE ABOVE THE HOT ZONE TEMPERATURETURE IN THE CASE OF THE HOT ZONE SCAVENGING CIRCUIT, AND MEANS TO COOL THE TEMPERATURE OF SAID ADDITIONAL GAS CHARGE BELOW THE COLD ZONE TEMPERATURE IN THE CASE OF THE COLD ZONE SCAVENGING CIRCUIT TO SUCH AN EXTENT THAT THE SCAVENGING GAS CHARGE SERVES AS THE CARRIER FOR HEAT ADDITION IN THE CASE OF THE HOT ZONE AND HEAT REJECTION IN THE CASE OF THE COLD ZONE; AND (F) AT LEAST TWO SHUT OFF DEVICES FOR SAID ADDITIONAL GAS CIRCUIT WHICH CONTROL THE INLET AND OUTLET OF THE SCAVENGING CIRCUIT TO THE ZONE; AND (G) MEANS TO CONTROL SAID SHUT OFF DEVICES SO THAT THEY OPEN AT LEAST ONCE DURING EACH CYCLE DURING THE PORTION OF THE CYCLE OF RELATIVELY SMALL PRESSURE CHANGE.