Abstract: In a scroll fluid compressor including orbiting and stationary scroll members having end plates and wraps in vortical form in upstanding positions on the end plates meshing with each other to define therebetween spaces for compressing a fluid introduced through an inlet line and discharging the compressed fluid through an outlet line, flat plates in vortical form having surface finishes of higher precision than the end plates are placed in valleys between the outer wraps and the inner wraps of the scroll members to enable the wrap of the orbiting scroll member to move in orbiting movement while having the forward ends of the wraps in sliding contact with the surfaces of the flat plates in vortical form.

Abstract: In a scroll-type compressor, the sum of pressure receiving areas of the upper end surfaces of crank portion of a crankshaft and the upper end surface of a balance weight is made substantially equal to the sum of the pressure receiving areas of the lower end surface of the shaft portion of the crankshaft and the lower end surface of the balance weight, the surfaces being subjected to internal pressures of the compressor. Consequently, only the downward force produced by the weights of the crankshaft and the rotor of a driving motor is applied to the crankshaft as an axial load which is born by a thrust bearing. Since the thrust bearing is required only to bear a small thrust load, it is free from the problems such as rapid wear and seizure.

Abstract: A refrigerating system including a refrigeration circuit and a scroll type compressor provided with two volume control mechanisms to allow the system to selectively perform full load operation and unloaded operation. The scroll type compressor includes two scroll members of known construction meshing with each other to define compression chambers and a suction chamber and is combined with the refrigeration circuit having an outdoor heat exchanger, an expansion valve, an indoor heat exchanger and a four-way change-over valve to provide a heat pump type refrigerating system. The volume control mechanisms each include a pair of bypass apertures in the fixed scroll member communicating with a valve chamber having a valve member slidably mounted therein and normally biased to an open position by a spring. The bypass apertures, of which one communicates with the suction chamber and the other communicates with one of the compression chambers, and the valve chamber constitute a bypass passageway.