To prevent the suction pressure of a compressor from dropping abnormally when calibrating an error by increasing the opening of an electronic inflation valve for a certain amount of time by a fixed amount in the error calibration of the travel of the electronic inflation valve when the compressor is operated at least for a constant amount of time.
When a compressor 1 of the freezing cycle of an air-conditioning device is operated at least for a constant amount of time, an electronic inflation valve 3 is totally closed temporarily, thus calibrating the error of the opening of the electronic inflation valve 3. At this time, the travel of the electronic inflation valve 3 is increased by a constant amount for a fixed amount or until the temperature of a compressor temperature detector 6 decreases to a constant value or less, thus allowing an amount of refrigerant exceeding the evaporation capacity of an evaporator 4 to flow to the evaporator 4 and one portion of the refrigerant to stay in an accumulator 5 via the evaporator 4 in the state of the liquid refrigerant. Then, when the travel of the electronic inflation valve 3 is fully closed, the liquid refrigerant in the accumulator 5 is evaporated and returned to the compressor 1, thus preventing the suction pressure of the compressor 1 from decreasing abnormally.
NAITO YASUHIRO
HORI SATOSHI
HITACHI SHIMIZU ENG KK