Patent GB-1149955-A (GB)
Title: Improvements in push-button thermo-electric ignition safety devices
IPC: F23N5/10
Filed: 1966-04-20
Abstract: 1,149,955. Burner controls. JUNKERS & CO. G.m.b.H. 20 April, 1966 [21 April, 1965], No. 17203/66. Heading F4T. [Also in Division E2] A thermo-electric ignition safety device of the kind in which two push buttons 11, 28 one for cut-off of a gas supply and the other for operating an ignition safety valve, are arranged side by side in a housing 1 for depression along parallel axes and are interlocked in such a manner that depression of the operating button 11 effects release of a latch which is operative to hold the depressed position of the cut-off button 28 comprises a slide 31 displaceable transversely of the said axes and a spring means 32 urging the slide towards a first position in which a blocking surface 38 on the slide is presented to a lug 352 on the operating button to prevent depression thereof and in which same position an inclined surface 36 on the slide is presented to a lug 351 on the cut-off button, such inclined surface being so arranged in conjunction with the lug on the cut-off button that depression of the latter causes displacement of the slide against the action of the spring means until a second position of the slide is reached in which the lug on the cut-off button is engaged with an undercut latching surface 37 on the slide, there being presented to the lug of the operating button in this second position a further inclined surface 39 on the slide which surface is so arranged in conjunction with the lug on the operating button that depression of the latter, besides now being permitted, causes sufficient displacement of the slide to effect disengagement of the lug on the cut-off button from the latching surface and hence unlatching of the cut-off button. As described the push buttons are slidable in a cover 101 of the housing 1; the housing includes a magnetic insert 2 which consists of an electromagnet 3, surrounded by a coil, and an armature 4 which is attracted by the electromagnet. The coil of the electromagnet 3 is connected to a thermoelectric element (not illustrated). The armature plate 4 is connected to a valve body 8 through a stem 7 which passes through a hub 6 in a cover which contains the armature and the electromagnet and in its inoperative position, the valve body 8 is forced against a seating 10 of the housing 1 by a spring 9. To start up an appliance associated with the ignition safety device, the push button 11 must be depressed and through a rod 12 displaces the valve body 8 away from the seating 10 so that the armature plate 4 is forced against the electromagnet 3; gas can then pass from an inlet aperture 13 through the valve, to a socket 15 which is coupled to an ignition burner and as soon as the ignition flame is lit a thermoelectric element is heated and current flows in the winding of the electromagnet 3, so that the armature plate 4 holds the valve open so long as the thermoelectric current flows. When the push button 11 is allowed to return to its initial position under the bias of a return spring 16, a main gas valve body 17, on the inner end of the push rod 12 is lifted away from a valve seating 19 against the force of a weaker spring 20 by a stop 18 on the push rod 12, so that gas can then flow from an inlet 21 through the valve and an outlet 22 to a burner for ignition by the ignition flame. The armature plate 4 is released from the electromagnet 3 by a lever 23 which is pivoted in a bearing 24 in the housing; one arm of the lever is bifurcated and engages under the valve body 8 and the other arm of the lever extends into the path of movement of a push rod 27 which is connected to the push button 28, the push button being biased to its initial position by a spring 29. Since the push button 11 can only be depressed when the push button 28 is in the depressed latched condition, the main gas supply to the burner is cut off before the push button 11 can be depressed and should ignition be unsuccessful when the push button 11 is depressed, then before it can be re-depressed the push button 28 which was released by depression of the push button 11 must be depressed once more and thus a period is provided during which gas can clear from the burner.