PURPOSE: To optimize the period of automatic defrosting operation, for a cooler so as to conform to the condition of practical use and prevent wasteful consumption of electric power by providing a controlling means for controlling the regular period of starting the defrosting operation to be prolonged in the case where a time integrated by integrating means is not exceeding a preset upper limit time.
CONSTITUTION: After defrosting operation for a cooler 6 is finished, integrating means 15, 18 calculate an opening time for doors 2a, 3a, 4a of a refrigerator. In the case where a time integrated by the integrating means 15, 18 is net exceeding a preset upper limit time i.e., in such a state that a total opening time for the doors 2a, 3a, 4a of the refrigerator is relatively short, so that the amount of frost to be produced on the cooler 6 becomes small, a controlling means 13 allows the regular period of starting the defrosting operation for the cooler 6 to be prolonged. As a result, when a state is such that a total opening time for the doors 2a, 3a, 4a of the refrigerator is relatively short and the amount of frost to be produced on the cooler 6 is small, the defrosting operation for cooler 6 is controlled so as not to be carried out in frequency more than necessity.
MURATA YASUKIYO
KAWAMURA SHINICHI
YOSHIOKA ISAHIRO
