GB706501A - Improvements in or relating to control systems for fluid fuel burners - Google Patents

Abstract

706,501.. Burner control systems. ROBERTSHAW-FULTON CONTROLS CO. May 22, 1951. No. 11952/51. Classes 75 (1) and 75 (3) Control apparatus for a fluid fuel burning appliance having main and pilot burners comprises means, e.g., an electric igniting resistor 20, for igniting fuel flowing from the pilot burner 22, a control device, e.g. a valve 14, responsive to a flame at the pilot burner for controlling the fuel supply to the main burner 10, a manually operable valve 16 for controlling the fuel supply to the control device and to the pilot burner, and a time-controlled valve 18 for controlling the fuel supply to the manually operable valve 16. The valve 18 is preferably solenoid operated, the time-control being effected by a switch 124 opened and closed by a timing mechanism 131. In operation the mechanism 131 is set to close the switch 124 at a predetermined time, and the control knob 68 of the manually operable valve 16 is set to the open position. During such movement of the knob 68 a cam 136 thereon closes a switch 132 in series with the switch 124, so that when the latter is closed by the timer 131 the solenoid of the valve 18 is energized through a circuit through a supply line L2, switches 124, 132, and a supply line L1. The igniter 20 is also energized, being connected in series with a ballast resistor 156 in the secondary circuit of a transformer 152, the primary circuit of which is completed through the line L1, a thermally controlled switch 104, the-primary winding of the transformer 152, the switches 132, 124 and the line L2. Fuel will then flow from a supply conduit 12 through a conduit 80, solenoid valve 18, conduit 72, valve 16 and conduit 24 to the pilot burner 22 where it is ignited by the igniter 20. The flame from the pilot burner 22 heats a bulb 60 containing expansible fluid, and connected by a capillary tube 58 with an expansible element 56, so that the latter expands to turn a lever 50 about a pivot 52 to move the valve member 38 of the valve 14 away from its seat 36 against the bias of a spring 40. Thus fuel will flow to the main burner 10 to be ignited by the flame at the pilot burner 22. The lever 50 in its rotation lifts the stem 90 of a valve 88 to allow fuel to pass from the supply pipe 12 through conduits 86, 84 to a standby pilot burner 82, and at the same time the lever movement de-energizes the igniter 20 by lifting a contact plate 112 from contacts 110 to open the switch 104. The apparatus is now in operation with the fuel flow to the main burner 10 controlled by a thermostatically actuated valve associated with the valve 16 and responsive to a temperature sensing element 76. When the timer 131 opens the switch 124 the solenoid valve 18 closes to cut off the fuel supply to the main burner 10 and the pilot burner 22. On extinction of the flame at the pilot burner 22 the bulb 60 cools and the element 56 contracts to permit closure of the valves 14, 88 so that the fuel supply to the standby pilot burner 82 is also cut off. A further embodiment is described in which the solenoid valve 18 is biased to open position and adapted to be closed when energized, so that in the event of electric power failure the system may still be operated, the pilot-burner 22 being ignited by a match or other igniter independent of the electric power supply.