To provide highly efficient high performance like that shown in the drawing during full/part road running by providing a power saving mechanism and an over-compression preventing mechanism and setting an incorporated compression ratio decided by the geometrical shape of a spiral lap vortex to be optimal at the time of power save running.
An incorporated compression ratio between spiral laps 23 and 33 is set to be optimal under a standard condition during part road running. During full road running, a power saving mechanism 40 introduces high pressure coolant gas before flowing into a condenser to a bypass route 43, presses a bypass valve 46, shuts off a bypass hole 44 and a return hole 45 and prevents coolant gas in a compression room P from returning to a lower pressure room 2A side. Also, when a pressure in the compression room P increases more than that of a high pressure room 2B, coolant in the compression room P is leaked to the high pressure room 2B by the action of an over-compression preventing mechanism 50 composed of an over-compression bypass hole 51 and an over- compression bypass valve 52, and thus over-compression is prevented.
KOBAYASHI NORIHIDE
FUSHIKI TAKESHI
SHIRAFUJI YOSHINORI
