Patent GB-409392-A (GB)
Title: Control apparatus for liquid fuel burners
IPC: F23N5/22
Filed: 1932-10-03
Abstract: 409,392. Electrically actuated valves. HADEN & SONS, Ltd., G. N., Trowbridge, Wiltshire, and HERRING, P. H., 60, Kingsway, London. Oct. 3, 1932, No. 27440. [Class 135.] A liquid fuel burner control apparatus comprises an electric motor arranged to move a body carrying cams which successively open a fuel supply valve, operate a fuel ignition device, and, should ignition of the fuel be not effected or fail, open a switch in the motor circuit, whereupon the cam-carrying body is returned to its initial position. The cycle of operations is then repeated a predetermined number of times unless ignition occurs. Liquid fuel is supplied to the burner from a pump FP on a shaft 28 driven through worm-gearing 26, 27 by the shaft 7 of an electric motor 4 which also drives an air compressor. Most of the air from the compressor passes to the burner but when the motor 4 is started some passes through a union 17 to a cylinder 18 and forces a piston 19 outwardly against the resistance of a spring 89. A pinion 22 carried by the piston 19 and driven through worm gearing from the shaft 28 is thereby caused to mesh with a toothed segment 23 on a drum 24 rotating on a bearing tube 11 surrounding the shaft 7. The drum 24 carries a number of cams operating successively tappets slidable in the upper web 37 of a frame 1 enclosing the control mechanism. A cam Sp.G first engages a roller 46 and tilts a lever 47 to raise a tappet 48 thereby opening a valve to supply gas to a nozzle adjacent the burner and closing a mercury switch Sp to energize a transformer T causing sparking at the nozzle. A cam 0 next engages a roller 57 on a lever 58 and lifts a tappet 59 to open a valve OV allowing liquid fuel to pass to the burner and to close a switch SS1 in the motor circuit. The fuel mixed with air from the compressor normally is ignited by the gas flame and the passage of the cam Sp.G past the roller 46 causes the gas supply and sparking to cease. Further rotation of the drum causes a cam S2 to lift a tappet 64 to open a mercury switch SS1 in the motor circuit, the tappet 64 being gripped and held in its raised position by a spring pressed plunger engaging in a groove 67. Previously to the opening of the switch SS2 a parallel circuit to the motor is completed through the left-hand contacts of a switch 88 located in the chimney stack or flue and rocked by the heat of the flame. The drum continues to turn and as the segment 23 disengages from the pinion 22 is given a rapid partial rotation by a roller 70 on a spring-pressed stirrup 76 engaging a ramp on a block 72 fixed to the drum. The burner now operates until current is shut off from the motor either intentionally, by the opening of a switch 167 by the furnace or room temperature, or by the opening of the stack switch 88 if the flame fails. The stoppage of the motor reduces the air pressure in the cylinder 18 causing withdrawal of the pinion 22 and the movement by a collar 76<1> on the pinion shaft of the stirrup 76 to its initial position. The drum 26 is then returned to its initial position by a spring 93, its rate of movement being controlled by a cam 103 on its surface operating the spring-pressed piston 101 of a dashpot 99. Oil previously drawn from a sump in the base 3 is forced by the piston 101 past an adjustable ball valve 109 and is discharged over the web 37 so as to lubricate the tappets before returning to the sump. At the end of its return movement a cam 111 on the drum withdraws the plunger supporting the tappet 64. Should ignition of the liquid fuel not be effected the motor will stop when the switch SS2 is opened and the parts will similarly be returned to their initial position. The control apparatus will then recycle, each abortive attempt at ignition causing a ratchet arm 116 to be lifted by a ratchet pawl 122 relatively to a hold-on pawl 130 and the fourth attempt resulting in the operation of a switch carrier 137 to open a switch SS3 in the motor circuit, when the apparatus is rendered inoperative until manually reset. The rate of fuel flow to the burner is controlled by an adjustable bye-pass valve 149.