Abstract: A closed refrigerating circuit for car air conditioning includes a compressor, a condenser, a refrigerant receiver, an expansion valve, and an evaporator. The expansion valve is provided with a constant pressure controlling mechanism for maintaining a pressure in the evaporator at a constant value. The compressor is provided with a continuously variable displacement mechanism for maintaining a superheating temperature of suction refrigerant at a constant value.

Abstract: An anti-rolling structure for a double headed piston of a disc cam type reciprocative compressor, comprising a cylinder block (1) through which a plurality of pairs of front and rear cylinder bores (4) are provided in parallel to a drive shaft (3) rotatably secured in the center of the cylinder block (1), and a double headed piston (8) slidably inserted in the respective pair of cylinder bores (4) for reciprocation in the longitudinal direction. A disc cam (13) having opposite sinuous surfaces (13') and rotatably accommodated within a cam chamber (5) is fixedly secured to the drive shaft (3), and a pair of front and rear cam rollers (14F, 14R) are arranged between the disc cam (13) and the piston (8) in a slidable and rotatable manner so as to nip the disc cam (13) between both cam rollers (14F, 14R) to transmit the rotation of the disc cam (13) to the piston (8) as a reciprocation in the longitudinal direction thereof.