JPS5697731A - Combustion controlling system - Google Patents

Abstract

PURPOSE: To restrain the overshoot of hot-water generated upon sudden decrease of an outlet amount of hot-water due to the descending of a water pressure caused by the using of water in other water feeding equipment and reduce a transitional period of time in the combustion control system for a proportional control type combustion instrument.

CONSTITUTION: A bridge is constituted with resistors 31W33, a thermistor 18 for detecting the hot-water temperature and a variable resistor VR as a temperature setting device, and a deviation output between connecting points A, B is inputted into a PID circuit effecting an integrating operation principally. The PID control circuit generates a signal for PID control in accordance with the inputted deviation and makes it the first input for a constant current driving circuit. The PID circuit inputs also an overshoot judging deviation between a connecting point C of the above-described resistor VR and the resistor 33 and the point A into an overshoot decision circuit and the existing or nonexisting of the overshoot is judged here in accordance with the polarity of the deviation. When the overshoot is judged, the conducted current of a proportional valve 13 is reduced forcibly through the constant current driving circuit and the amount of the gas is reduced.

COPYRIGHT: (C)1981,JPO&Japio