Patent ID: 7150158

Claim:
A freezing prevention system for a refrigeration device including a refrigerant compressor for compressing and discharging refrigerant and a refrigerant evaporator for evaporating the refrigerant after being cooled and decompressed, the freezing prevention system comprising: a temperature detection unit disposed in the refrigerant evaporator, for detecting a refrigerant temperature in the refrigerant evaporator; and a control unit for controlling operation of the refrigerant compressor based on the refrigerant temperature detected by the temperature detection unit, wherein; the control unit includes a calculating means for calculating an integral value of the detected refrigerant temperature integrating with respect to a passed time after the detected refrigerant temperature becomes equal to or lower than a predetermined integrating start temperature; the control unit stops the operation of the refrigerant compressor when the integral value calculated by the calculating means becomes equal to or larger than a predetermined value; the control unit further includes another calculating means for calculating another integral value of detected refrigerant temperature integrating with respect to a passed time after the detected refrigerant temperature becomes higher than the predetermined integrating start temperature; and the control unit re-starts the operation of the refrigerant compressor when the another integral value calculated by the another calculating means becomes equal to or larger than a predetermined re-start value.