JPS5783823A - Controller for drier - Google Patents

Abstract

PURPOSE:To improve the drying efficiency, by detecting the humidity of the exhaust air from a drying room and by controlling the exhaust air flow rate or the calorific value of a heater for hot blast so that the relative humidity of the exhaust air is held constant approximately. CONSTITUTION:A relative humidity detecting part 5 detects the humidity of the exhaust air from a drying room and outputs a relative humidity signal Va. The signal Va reduces the opening of a valve 11 to reduce the exhaust air flow rate according as the relative humidity in the exhaust air is lowered. When the temperature of the hot blast in the drying room rises, the speed of water vaporization from cloths is accelerated without raising the calorific value of a heater 28 for hot blast because the saturation vapor pressure rises. When drying is advanced to reduce the water quantity, the quantity of vaporization heat taken from the hot blast is reduced, and therefore, a detection temperature signal VT1 rises, and a relative exhaust air temperature signal Vb of the output of an exhaust air temperature detecting part 12 rises. According as these signals rise, a heater cotrol signal Vc from a calorific value setting part 20 is reduced to lower the calorific value of the heater 28. When the temperature of the exhaust air rises furthermore and the signal VT1 becomes higher than a set temperature signal VS1, a stop signal Vd is outputted from a drying completion detecting part 30 to stop the drying operation.