EXPANSION VALVE CONTROL DEVICE FOR AIR CONDITIONER

摘要

PURPOSE:To make an efficient operation by a method wherein a throttling amount of an expansion valve is varied in response to a variation of the interior or ambient air temperature. CONSTITUTION:A control circuit 16 provided with a microcomputer has AC-DC converter 17 at its input side and a signal of a thermistor 19 for sensing and taking out an interior dry bulb temperature is applied as an input. A sensing of an external wet bulb temperature is performed such that the signals are inputted from the humidity sensor 20 and the dry bulb thermistor 18. At the output side of the control circuit 16 are provided relay coils 21 and 22 for controlling energization of a compressor 1 and a four-way valve 2. The compressor 1 and the four-way valve 2 are controlled for their operations through the relay contact points 21a and 22a. The expansion valve 4 performs a control operation by transmitting a pulse from the control circuit 16. With this arrangement, even if the interior or ambient air temperature is varied, a balance of the optimum refrigerating cycle is not varied and so an efficient operation can be performed.