PURPOSE: To optimally control a refrigerating cycle by detecting and comparing temperatures before and after an expansion valve and a temperature of a compressor suction unit by an expansion valve control microcomputer, discriminating between cooling and heating regardless of a unit control microcomputer, and controlling the valve during defrosting so that compressor suction unit superheat of a reverse cycle becomes constant.
CONSTITUTION: In a refrigerating cycle, a refrigerant output from a compressor 1 is air-cooled by an outdoor heat exchanger 3 via a four-way valve 2, and pressure- reduced by an expansion valve 4. Temperatures before and after it are measured by thermistors 8, 9. The pressure-reduced refrigerant cools by an indoor heat exchanger 5. The refrigerant is sensed at its temperature by a thermistor 7 immediately before suction to the compressor 1 via a liquid reservoir (b) through the valve 2, and the valve 4 is controlled. A defrosting operation upon heating is controlled by the expansion valve. And, since a maximum limit cycle low pressure is operated at a higher value while a suitable superheated refrigerant gas is ensured to the compressor, a compressor input can be increased. And, its low pressure is controlled to higher, a refrigerant flow rate during defrosting is increased to easily obtain a defrosting heat source, and a defrosting time is shortened.
TERADA HIROKIYO
HANADA MASAMICHI
HORIUCHI NORIAKI
