AIR-FUEL RATIO CONTROL DEVICE OF BURNER

摘要

PURPOSE:To be able to control air-fuel ratio constantly to a target one regardless of the temp. of combustion gas by a method wherein the temp. of combustion gas generated by a burner is detected by a temp. sensor and a reference value is decreased as the temp. of this gas rises up. CONSTITUTION:A part of flames is introduced into an lead-out tube 34 and the residual oxygen concentration in combustion gas produced by the flames is detected by an O2 sensor 36. A temp. comparison circuit 54 compares a set temp. set previously by a temp. set dial 58 with the temp. of burning gas or hot wind temp. detected by a temp. sensor 44 and a deviation signal obtained by deducing the output of the dial 58 from the output of the sensor 44 is input into a fuel amount control circuit 56 and as the temp. of combustion gas rises up, the reference voltage in an air amount circuit 52 is decreased. The circuit 52 compares the output of the O2 sensor with the reference voltage and when the output of the O2 sensor is higher than the reference voltage, the revolution speed of a blower motor 18 is increased to control an air-fuel ratio by increasing the air supply amount.