US Patent 7536872 High pressure control valve

A high pressure control valve is arranged in a refrigerant passage formed from an internal heat exchanger to an evaporator 4 in a refrigerating cycle of CO2 refrigerant having the internal heat exchanger 8. The high pressure control valve 3, 3A to 3F controls refrigerant pressure on the internal heat exchanger outlet side according to a temperature of the refrigerant at the outlet of the radiator. Into a temperature sensing section (airtightly closed space A), the inner pressure of which is changed according to the refrigerant temperature on the radiator outlet side, CO2 refrigerant, the charging density of which is 200 to 600 kg/m3, preferably 200 to 450 kg/m3, is charged.