GB1427709A - Ignition device for a gas-fired appliance - Google Patents

Abstract

1427709 Ignition devices PARKINSON COWAN APPLIANCES Ltd 9 Oct 1973 [10 Oct 1972] 46636/72 Heading F1B [Also in Division F4] An ignition device for a gas fired appliance comprises a spark gap 24 arranged in use adjacent a burner outlet of the gas fired appliance such that in use a flame and/or hot gases produced by the burner will bridge the spark gap, a first capacitor 14 chargeable in use by a D.C. source, semi-conductor switch means 20 for discharging the first capacitor 14 through the primary winding 18 of a transformer when the semi-conductor switch means is, in use, conductive, a second capacitor 15 chargeable through a resistor 27 when it is required to cause operation of the ignition device, the secondary winding 23 of the transformer together with the spark gap 24 being connected electrically in parallel with the second capacitor and the resistance of the gap modifying the voltage across the second capacitor when a flame is present, voltage sensitive means 22 operable to cause conduction of the semiconductor switching means when the voltage across the second capacitor attains a predetermined value and means for temporarily raising the voltage across the second capacitor after is has been charged when the ignition device is initially energized. As shown the means for temporarily raising the voltage across the second capacitor comprises a third capacitor 26 which has a capacitance substantially larger than the capacitance of the second capacitor. Fig. 3 (not shown) relates to a device having four ignition spark gaps for use with a hot plate of a cooker having four gas rings.