SCROLL EXPANDER

PROBLEM TO BE SOLVED: To reduce leakage of working fluid between the ends of orbiting scroll wraps and a panel of a fixed scroll by increasing orbital torque to obtain stable orbiting force.SOLUTION: The wraps of the fixed scroll and the orbiting scroll form involute curves. The wraps of the fixed scroll are constituted of two rolls of wraps 72a, 72b in which phases are shifted by 180° with each other around an involute base circle I, and the wraps of the orbiting scroll are constituted of two rolls of wraps 74a, 74b in which phases are shifted by 180° with each other around an involute base circle I. The fixed scroll wraps and the orbiting scroll wraps are arranged with the phases shifted by 90° with each other to the involute base circles. With this, load acting points D generated by pressure differences of gas pockets Gadjacent with the orbiting scroll wraps interposed between them are increased and high torque is loaded to the orbiting scroll wraps.