PURPOSE: To stabilize the operation of a refrigerating plant and reduce the effect of noise generated by a fan by incorporating a plurality of relations between a rotary speed and a rotation decision factor into this control system and changing automatically these relations based on a different factor.
CONSTITUTION: A compressor 1, an outdoor heat exchanger 2, an expansion mechanism 3 and an indoor heat exchanger 4 are coupled with a refrigerating piping system 5 respectively, thereby forming a refrigerant circulation system 6. After the refrigerant from the compressor 1 is circulated as indicated by the arrow and the open air is heated with the outdoor heat exchanger 2, the heating value from the indoor air is absorbed with he indoor heat exchanger 4 and this operation is repeated so as to cool the indoor air. A controller 11 is provided with a microcomputer which receives the output transmitted from a refrigerant pressure sensor 10 and a variable gearbox which changes the speed of an outdoor fan 2a. Therefore, when a background noise is high, even it an attempt is made to reduce the converging value of higher pressure and increase the rotary speed of the fan, the effect of noise will be minimized. When the background noise is low, it is possible to reduce the noise effect by increasing the converging value of higher pressure and moderating the rotary speed of the fan as much as possible.
KATOGI KENICHIRO
TAKI KATSUHIKO
HITACHI SHIMIZU ENG KK