GB1250979A - - Google Patents

Abstract

1,250,979. Controlling burners. UNDERWRITERS SAFETY DEVICE CO. 20 May, 1969 [28 June, 1968], No. 25540/69. Heading F4T. [Also in Divisions F2 and H1] A single operating member simultaneously operates a gas valve for a cooker burner and a cam switch for electrically igniting the burner. The gas valve has a body 30, a jet 26, a gas inlet 42 and a valve stem 38 for opening and closing the valve. Upon rotation of stem 38 the valve moves rapidly from a closed position to a fully open position and thereafter to a gradually more closed position. Mounted on studs 36 are a switch body 44 and a cam plate 46. Stem 38 projects through holes 54 and 58 and mounted on stem 38 are a camming sleeve 48 and a handle 96. On camming sleeve 48 is an axially facing cam track 64 which operates on moving contacts 90, 92 and brings them into engagement with fixed contacts 80, 82. Contacts 90, 92 are electrically both connected to terminal 78 and are normally resiliently biased away from fixed contacts 80, 82. In a second embodiment, Fig. 5 (not shown), contacts 80, 90 are omitted. In a third embodiment, Figs. 7, 8 (not shown), there is one moving and one fixed contact in the switch body and one moving and one fixed contact in the cover, the two moving contacts being electrically connected together and there is an axially facing cam track on both ends of the camming sleeve. The ignition circuit is shown in Fig. 6. A capacitor 100 is charged through diode 106 and resistor 102 from alternating current source 132. The switch coupled to the gas valve is shown at 138 and through a circuit, not shown or described, through trigger element 122 applies a trigger pulse to the gate 120 of SCR 110 to render it conductive. Capacitor 100 then discharges through SCR 110 and the primary 116 of transformer 118 which causes a spark across electrodes 128 connected to transformer secondary 130. Thereafter the negative voltage swing caused by discharge of capacitor 100 renders the SCR non-conductive until trigger element 122 allows another pulse of current through. Element 122 may be a neon bulb or may be a diac.