CONTROL DEVICE FOR AUTOMATIC VENTILATION FAN

• Main Author: SAKAHARA TAKASHI
• Format: Patent
• Language: English
• Published: 30.03.1987
• Subjects: AIR-CONDITIONING, AIR-HUMIDIFICATION, VENTILATION, USE OF AIRCURRENTS FOR SCREENING; BLASTING; HEATING; LIGHTING; MECHANICAL ENGINEERING; RANGES; VENTILATING; WEAPONS

PURPOSE:To make the operation control of high accuracy simply and all the time for a ventilation fan which utilizes a detection element which senses a reducing gas and changes its resistance accordingly by absorbing the variation in the resistance value due to the variation in temperature and humidity in the environment and the variation in resistance value due to the temporal variation. CONSTITUTION:The variation in the resistance value of a detection element 1 is changed into an off-time of square wave by means of a non-stable multi-vibrator circuit 2 to become detection signal and inputted to a microcomputer 4 through a waveform shaping circuit 3. Then it receives the signal from a reference time generation circuit 5 and measures the time to take in the detection output as a reference value by the stable resistance value of the detection element 1 by means of a microcomputer 4, and after a prescribed time has passed, the detection output is once taken in as a reference value. After this, when the resistance value becomes positive with respect to the reference value with changes in temperature and humidity of the environment, changes with time, etc., reference value is renewed by taking it as a new reference value. When the reference value does not change after a certain time has passed, the reference value is forcibly reduced a little to a lower resistance value. With this arrangement changes in resistance value due to the changes in temperature and humidity of the environment and the temporal change in long term are absorbed.