PURPOSE: To prevent the discharging of lubricating oil due to its foaming, by operating a compressor at a low or intermediate speed for a certain while after starting of the compressor, and then operating the same at a high speed.
CONSTITUTION: Coolant is passed in the direction shown by arrows in the drawing. However, since both of the cycle and a compressor are cool at the time just after starting of the compressor, the coolant is drawn into the compressor 1 from a suction port S in the phase of liquid, and after being compressed by the compressor 1, is then discharged from a discharge port (d). Taking the time (t) passed after starting operation of the compressor 1 at the axis of abscissa and the speed of rotation of the compressor 1 at the axis of ordinate, the speed of rotation of a compressor motor is controlled as shown by a curve 10 in the drawing, whereby the compressor performs gas compressing operation at an intermediate speed, so that the possibility of lubricating oil to cause foaming is decreased.
IIZUKA KENICHI
UZUHASHI HIDEO
SERIZAWA YUKIO
