| 摘要 |
PURPOSE:To control a refrigerating machine so that a deficiency in cooling is caused in a high temperature range while saving operation is performed in a low temperature range, by controlling the operation rate of the refrigerating machine through a closed loop when the ambient temperature enters into the prescribed high temperature range. CONSTITUTION:A differential amplifier 6 which inputs the output of an air sensor 7 detecting room temperature to be brought under cooling control is provided as well as a comparator 8, and a saw-tooth wave generator 5 which generates a control signal for performing control while the operation rate of the refrigerating machine is regarded as a duty ratio proportional to the detected temperature of the comparator 8 within a prescribed duty cycle time is provided. Further, a minimum off-time limiting circuit 3 and a minimum on-time limiting circuit 4 are provided to limit the off time width of the control signal so that the refrigerating machine does not respond to the control signal which is less than minimum off time. When ambient temperature detected by the sensor 7 enters into a prescribed high temperature range, a differential amplifier 10 cuts off a minimum off time, thus controlling the refrigerating machine so that a deficiency in cooling is caused. |
