JPS5777220A - Air conditioner for vehicle - Google Patents

Abstract

PURPOSE:To prevent the deterioration of durability of a magnet clutch by operating an acceleration switch signal and a signal of a temperature sensor detecting a vehicle interior temperature, outside air temperature and cooler temperature and by controlling the OFF time of a compressor depending on the detected temperature at the acceleration time. CONSTITUTION:When a negative pressure exceeds a given value, a timer 3 is synchronized with an input's differential signal V1 by the ON signal of an acceleration switch 1 and generates the timer signal V2, which enters an integral circuit 5 and AND gate 8 through a reverse circuit 4. The integral circuit 5 generates a signal V3, which increases for a t1 time only and decreases thereafter, while the output V4 of a temperature sensor 2, detecting the temperature of any one of the interior of a vehicle, outside air and cooler, is compared with the signal V3 by a comparator 7. Then, a signal V5, whose value becomes L for the time of V3>V4, is output, while the OFF time of a compressor within the timer time t1, caused by the acceleration signal, is controlled by an output transistor 9 depending on the temperature, whereby the deterioration of clutch durability and cooling efficiency are prevented.