SAFETY DEVICE FOR ALL PRIMARY BURNER

摘要

PURPOSE:To permit the setting of threshold values of respective judgements arbitrarily and the control of the titled burner at respective optimum points by a method wherein the detection of the shortage of oxygen is judged by the signal of a flame rod while the detection of air-fuel ratio is decided by the signal of an exhaust gas sensor. CONSTITUTION:The ion current of a flame is detected by a detecting circuit 21 through a flame rod 20 provided so as to be opposed to wirenet flame ports 16. In case there is a difference between an oxygen concentrations in a tube and outside of the tube, an electromotive force is generated in an exhaust gas sensor 22 provided in the passageway of the exhaust gas. The exhaust gas of combustion is introduced to the outside of the tube and indoor air is introduced into the tube while a remaining oxygen concentration in the exhaust gas is detected in another detecting circuit 23 by the difference of concentrations to obtain the air-fuel ratio of a burner. The judgement of the air-fuel ratio and that of the shortage of oxygen are effected by signals from respective independent sensors as described above, therefore, respective threshold values may be set arbitrarily and the burner may be controlled at the optimum point.