JPS631498B

A combustion controlling apparatus is disclosed which is used in a pulse combustion apparatus for generating flames intermittently and which has a flame-rod type flame detector. In this combustion controlling apparatus, a low AC source voltage is converted to a DC voltage and then this DC voltge is converted by an inverter to an AC of about 100 V and 800 Hz which is then supplied to the igniter and flame rod. The inverter comprises a pair of transistors and a transformer having a primary winding with its center tap connected to a DC source voltage and both ends thereof connected to the respective collectors of the transistors which are in turn cross-coupled to the bases of the mating ones through respective series circuits each consisting of a capacitor and a resistor. Thus, in a secondary winding of the transformer, a rectangular wave voltage is produced. The inverter can supply a high voltage to the flame rod during ignition, enabling easy fire detection and can prevent the transistors from generating heat. Moreover, the combustion controlling circuit and fuel valve driving circuit are supplied with power from the inverter, and thus safety is improved.