DELAYED ACTION TYPE PILOT FLAME RETAINING DEVICE FOR BURNING APPARATUS

摘要

PURPOSE:To enable reignition of the main burner within a limited time, while ensuring safety without leaving any pilot flame, by a system in which the same condenser is used both for discharging and charging timers so that the ignition of the main burner is controlled through the igniter which is turned ON depending on the results of comparison of the charging voltage with the trivalent reference voltage. CONSTITUTION:With the ignition switch 4 set to ON, the transistors 11 and 12 are turned ON to cause the condenser 13 to be charged to the low voltage level VL on the trivalent reference voltage generator 1. With this, the switching element 18, via the drive circuit 17, is set to ON, activating, via the pulse transformer 19, the electromagnetic valve 20 and the relay 21 to ignite the igniter 22 with a pilot flame. When the output of the flame sensor 5 exceeds the reference voltage level 7 and said condenser 13 is charged to higher voltage levels, said switching element 18 is activated to turn ON the electromagnetic valve 25. With this, the main burner becomes ignited and the pilot flame on the igniter 22 becomes extinct. Then, when the ignition switch 4 is set to OFF, said condenser 13 starts discharging, but when said ignition switch 4 is set to ON before the low voltage level VL is reached, the main burner is capable of reignition.