A method for determining the oil circulation rate ocr of a refrigerant - oil mixture in a refrigerant of a vehicle air conditioner

摘要

The invention relates to a method for determination of the oil circulation rate ocr of a refrigerant - oil mixture in a refrigerant circuit (1) of a vehicle air conditioning system with an evaporator (2), a gas cooler or refrigerant condenser (3), a refrigerant compressor (4), a the evaporator (2) connected upstream of the expansion element (5), a refrigerant - oil mixture without subcooling cold accumulating means header section (3.1) in the high-pressure region of the refrigerant circuit (1), a relative to the vertical direction of the vehicle in the lower area of the cold means header section (3.1) arranged pressure - temperature - sensor (6) and a memory unit (7.1), in which a the dependence of the saturation pressure (p_s) of the liquid refrigerant - oil - mixture of its oil mass share (y) and of its temperature (t) is stored a family of curves, in which the pressure (p₁) and the temperature (t₁) of the liquid and saturated refrigerant - oil mixture by means of the pressure - temperature - sensor (6) is measured, and with the measured pressure - and temperature value (p₁, T₁) from the family of curves, by means of a computer unit (7) of the oil mass share (y₁) as the oil circulation rate ocr of the refrigerant - oil is determined. If the refrigerant - oil mixture is not in a single-phase and liquid saturated state is present, by means of the measurement of pressure - and temperature values both in front of the expansion element (5) as well as after the expansion element (5) of the steam content and this results in the liquid portion of the refrigerant is determined. Together with the oil mass share results in the oil circulation rate ocr.