PRESSURE DETECTING DEVICE, SUPERHEAT DEGREE DETECTING DEVICE AND CONTROL DEVICE FOR COOLING SYSTEM

摘要

PROBLEM TO BE SOLVED: To perform control with high accuracy even when a pressure detecting means without high accuracy is used, in a control device for a cooling system controlling the opening of an electric expansion valve of a refrigerating cycle. SOLUTION: An outlet temperature of an evaporator 4 of the refrigerating cycle is detected by a temperature sensor 6. The pressure from a pressure switch 10 is sampled to determine a pressure difference value. A steam pressure equivalent temperature difference value corresponding to the pressure difference value in a neighborhood region of steam pressure equivalent temperature of a refrigerant is calculated. The steam pressure equivalent temperature is calculated by adding the temperature difference value and an offset value to an evaporator inlet-side temperature. The steam temperature equivalent pressure is transformed inversely from the steam pressure equivalent temperature. A third superheat degree is calculated from an evaporator outlet-side temperature, the steam pressure equivalent temperature based on the pressure difference value or the like. Operating force of the electric expansion valve is calculated on the basis of the third superheat degree. COPYRIGHT: (C)2007,JPO&INPIT