Patent ID: 8783045

Claim:
A cryorefrigerator comprising: a compressor for supplying a pressurized gas, the compressor comprising a return side and a supply side; a regenerator comprising a regenerator warm end and a regenerator cold end; an expander comprising an expander warm end and an expander cold end, the expander cold end operatively connected to the regenerator; a buffer volume; a valve unit consisting of a single buffer control valve placing the buffer volume in fluid communication with the regenerator warm end and the expander warm end without any other intervening valves between the buffer volume and the regenerator and the expander; a first valve placing the supply side of the compressor in fluid communication with the regenerator warm end and the expander warm end without any other intervening valves between the supply side of the compressor and the regenerator and the expander; and a second valve placing the return side of the compressor in fluid communication with the regenerator warm end and the expander warm end without any other intervening valves between the return side of the compressor and the regenerator and the expander; and a controller configured to open and close the valves in sequence so that: the buffer control valve opens and closes, then the first valve opens and closes, then the buffer valve opens and closes, and then the second valve opens and closes.