GB624742A - Improvements in or relating to control and ignition apparatus for fuel burners - Google Patents

Abstract

624,742. Lighting gas burners. DIXON, M. G. (Robertshaw Thermostat Co.), Jan. 28, 1947, No. 2700. [Classes 75(i) and 75(iii)] A main oven gas burner 10, Fig. 1, is supplied with fuel from a manifold 14 through a pipe 18 controlled by a main fuel cock 20 and a safety control valve 22 comprising electromagnetic means 62 adapted when energised by a thermocouple 108 heated by a burner 112 to hold the valve 22 open, and provided with resetting means actuated on the opening of the fuel cock 20 to open the valve 22, said resetting means being returned to its inoperative position after a predetermined period following ignition of the burner during which period the thermocouple 108 has energised the electromagnetic means. Fuel enters a chamber 28, Fig. 2, of the control device 22 through an inlet 26 and passes through an opening 32 controlled by a valve member 36 to an outlet 34 leading to the burner 10. On turning a knob 21 to open the fuel cock 20 a cable 150 is pulled to release a latching member to move a bimetallic element 136 into the path of the pilot burner 72. The element 136 forces into the device 22 a shaft 104 to displace a valve member 94 from its seat to permit flow of fuel from the pipe 78 to the outlet 92 and pipe 74 supplying pilot burners 70, 72 and a thermocouple heating burner 112. At the same time fuel is prevented from flowing to the main burner 10 by a disc 42 which is forced downwardly by the rod 104 to close the opening 32. After a predetermined time delay, during which the strip 136 becomes heated, it warps to trip the latching element to be moved thereby out of the flame of the burner 72 whilst releasing the rod 104. The valve member 94 is then returned to its seat by a spring 97 and the fuel supply to the pilot burners 70, 72, and thermocouple heating burner 112 is cut off. The thermocouple 108 becomes sufficiently heated to energize the electromagnet 62 before the rod 104 is released so that the valve member 36 is held away from its seat, whilst a spring 50 forces the disc 42 away from the opening 32. Fuel now flows to the main burner 10 which is ignited by an ignition pilot burner 114, or where the latter burner is not provided by the thermocouple heating burner 112 supplied by the fuel remaining in the pipe 74. If at any time the thermocouple 108 ceases to be heated by the pilot burner 114 or, where the latter is not provided, by the main burner 10, the electromagnet 62 is de-energised and the valve member 36 cuts off the fuel supply to the burner 10.