PURPOSE: To achieve a higher efficiency and a higher reliability by performing a control of the suction temperature corresponding to the number of revolutions of a compressor for the cooling operation and a control of the difference between the suction temperature and the temperatures of heat exchangers in the medium and low speed ranges of the compressor requiring much operating time and under the air conditions of a low temperature to regulate the temperature of the compressor to a specified value when the compressor reaches a high temperature.
CONSTITUTION: By the selection of an operation mode, the suction temperature and the temperature of a compressor 1 are taken in as for the cooling operation to judge the control of the suction temperature of the compressor or the control of the temperature of the compressor based on the temperatures and the difference from a target value is computed to drive an electronic type expansion valve 4. In the heating operation, the temperature of an outdoor heat exchanger 8 is taken in other than the suction temperature and the temperature of the compressor and like the cooling operation, the contents of the control is judged to drive the expansion valve 5. In the case of the cooling, the suction temperature of the compressor is controlled to a target temperature corresponding to the number of revolutions of the compressor when the temperature of the compressor is below a specified value or the temperature of the compressor is controlled to a target value when it exceeds the specified value. Moreover, even during the control of the temperature of the compressor, when the suction temperature of the compressor exceeds a control changeover temperature, a switching is made over to the control of the suction temperature.
KOGURE HIROSHI
KANEKO TOMOMICHI
HAYASHI MASAKATSU
