PURPOSE: To prevent to consume useless electric power in case a temperature is reduced in a short period of time to transfer a constant temperature space into a constant temperature condition by a method wherein the operation of a refrigerating machine is controlled by a sensor, detecting the temperature of the constant temperature space, and a temperature regulator, comparing the detected temperature with a set value.
CONSTITUTION: In a condition (at a time t1 in the diagram) that the temperature in the constant temperature tank 1 is reduced to a predetermined temperature in a short period of time, the operating switches 14, 15 of first and second refrigerating machines 4, 5 are being thrown by a temperature setter 16. In this case, electric power, supplied to an electric heater 2, is controlled by an electric power regulator 13 to the minimum thereof. Then, the operating switch 15 of the second refrigerating machine 5 is opened by the temperature setter 16 when the temperature of the wall 1A of the constant temperature tank has approached to the temperature in the same tank (at the time point t2). Whereby, the operation of the refrigerating machine 5 is stopped and the temperature in the same tank is transferred to the constant temperature condition. In this condition, the electric heater 2 and the machine 4 are operated to maintain the temperature thereafter in constant. In this case, the electric power supplied to the electric heater 2 is controlled by the electric power regulator 13 so that the power balances with the cooling heat amount of the refrigerating machine 4.
WATANABE HIROSHI
FUKUSHIRO TAKESHI
