Patent ID: 7555908

Claim:
A gas refrigeration device operating on a gas refrigeration cycle comprising: a gas expansion cylinder ( 364 ) formed to receive a gas displacing piston ( 362 ) movably supported therein for movement over a stroke range ( 84 ) and formed with an open warm end and an opposing sealed cold end; a base element ( 616 ) disposed over the open warm end and formed with an aperture ( 618 ) passing therethrough for providing access to the gas expansion cylinder; a gas expansion space ( 380 ) formed between the sealed cold end and the gas displacing piston ( 362 ) for receiving refrigeration gas therein and further wherein the volume of the gas expansion space ( 380 ) is variable from a minimum volume, when the gas displacing piston ( 362 ) is at a top end ( 85 ) of the stroke range ( 84 ), to a maximum volume, when the gas displacing piston ( 362 ) is at a bottom end ( 83 ) of the stroke range ( 85 ); a compression spring ( 622 ) disposed between the base element ( 616 ) and the gas displacing piston ( 362 ) for exerting a spring biasing force against the gas displacing piston ( 362 ) for forcing the gas displacing piston to the top end ( 85 )of the stroke range; and, a tensioning element ( 606 ) passing through the aperture ( 619 ) and connected to the gas displacing piston ( 362 ) for exerting a tension force on the gas displacing piston ( 362 ) directed substantially opposed to the spring biasing force.