To enable a height of refrigerant within a liquid receptor to be measured in an accurate manner by a method wherein an electrostatic capacitance generated at a connector cable between an electrostatic capacitance conversion circuit and a pole plate is eliminated under application of an amplifier.
As an amount of liquid refrigerant is varied and a height of a liquid refrigerant 15 is varied, a rate between a part contacted with the liquid refrigerant 15 and another part contacted with gaseous refrigerant 16 at a pole plate 14 is varied. As a result, an electrostatic capacitance of the pole plate 14 is varied due to the fact that there are several times of differences in a specific inductive capacity between the liquid refrigerant 15 and the gaseous refrigerant. If the specific inductive capacity of the liquid refrigerant 15 is kept constant, its height is proportional to a value of electrostatic capacitance of the pole plate 14. Accordingly, it is possible to judge an excessive amount of refrigerant or a lack of refrigerant from a proper amount of refrigerant within a cycle by comparing the height of the liquid refrigerant 15, i.e., an amount of liquid refrigerant within the liquid receptor 8 at that time, i.e., an amount of refrigerant within a cycle, i.e., a reference height of the refrigerant in the liquid receptor 8 on the basis of an electrostatic capacitance of the pole plate 14. Accordingly it is possible to prevent an excessive or a lack of cooling capability produced from the excessive or lock of amount of refrigerant and further to prevent an accident of damage of a compressor or the like in advance.
KINOSHITA KAZUTO
YASUDA HIROSHI
KOKUNI KENSAKU
NAKAYAMA SUSUMU
