Abstract: A refrigerator for cooling a space inside thereof with a Stirling refrigerating engine includes state detection means for detecting an excessive cooling critical state of the Stirling refrigerating engine and excessive cooling prevention means for preventing excessive cooling of the Stirling refrigerating engine based on detection of the excessive cooling critical state by the state detection means. Excessive cooling of the Stirling refrigerating engine can thus be prevented.

Abstract: The controller of a cooling box is configured such that when the temperature of the warm head of a Stirling refrigerating machine exceeds a reference temperature, it maximizes the speed of a heat radiation fan and the output of a circulation pump, and minimizes the output of the Stirling refrigerating machine. If the temperature of the warm head exceeds a critical temperature even after this control, it stops the Stirling refrigerating machine. Therefore, as compared with the case of stopping the Stirling refrigerating machine immediately after the temperature of the warm head has exceeded the critical temperature, the reliability of the cooling box can be improved.