Patent ID: 6460354
Filing Date: 2002-10-08
Classification: F25B,Y02B

Abstract:
Apparatus for detecting low charge of a working fluid in a heat transfer system of the type having a fluid circuit comprising a compressor for pressurizing working fluid received from an evaporator, a condenser for cooling the working fluid received from the compressor, and an expansion device for controlling flow of the working fluid between the condenser and the evaporator, the apparatus comprising: a working fluid state sensor operative in response to a control signal and disposed in the fluid circuit on the outlet side of the evaporator to produce a working fluid state signal; and control means for providing said control signal to the sensor and for controlling operation of the heat transfer system based on a comparison of said working fluid state signal with a state set point; said control means detecting a low charge condition of the working fluid when the state signal indicates the working fluid, in a superheat condition, exceeds a first predetermined threshold over a first predetermined time with the expansion device in a fully open condition.