| 摘要 |
PURPOSE:To prevent the frosting of an evaporator and give full play to the cooling capacity in a car cooler by providing a circuit to stop a refrigerant compressor when the temperature of the air on the blow-off side of the evaporator is maintained under a temperature a little higher than a fixed value for a fixed time as well as the same temperature is lowered as far as this fixed value. CONSTITUTION:A comparison amplifier OP1 is brought to a low-level output when the air temperature on the blow-off side of an evaporator is lowered to a fixed value T1 by the detection output of a thermistor Th1, while a comparison amplifier OP2 when the same temperature is lowered to a fixed value T2 lower than T1. The amplifier OP2 is brought to a high-level output when the temperature is raised to a fixed value T3. When the amplifier OP1 is brought to the low-level output, a comparison amplifier OP3 is brought to a low level after a fixed time by a delay circuit composed of a resistance R7 and a condenser C. At this stage, since the amplifier OP2 is also brought to the low level by a diode D2, a refrigerant compressor is stopped until the temperature on the blow-off side is raised to T3, and during this stoppage, defrosting is carried on. When the temperature on the blow-off side is again raised above T1 within a fixed time after being lowered to T1, the amplifier OP1 is returned to the high level via a diode D1 and started to operate when the temperature is again lowered to T1. |
