GB987364A - Temperature control and ignition devices for fluid fuel burning apparatus - Google Patents

Abstract

987,364. Burner control apparatus. ROBERTSHAW CONTROLS CO. May 15, 1963 [June 15, 1962], No. 19358/63. Headings F4F and F4T. A control and ignition device for an oven 20 comprises a pilot burner 24 having an aperture 54 producing a small standby flame and apertures 62 and 65 producing large flames 36, 36A adapted to ignite a main burner 22, a thermostatic bulb 32 responsive to the temperature of the oven and controlling the flow of gas to the pilot burner and a second thermostatic bulb 35 responsive to the large ignition flame 36 of the pilot burner and controlling the flow of gas to the main burner. The pilot burner is supplied through a pipe 94 having an adjustable nozzle 38 and also through a pipe 78 having a regulating valve 76 controlled by a construction 30 connected to the oven thermostatic bulb 32. The main burner is supplied through a gas valve 26 connected to the thermostatic bulb 35. In operation when the oven temperature drops below a predetermined level the pilot valve 76 opens to supply additional gas to the pilot burner to produce the enlarged flames 36, 36A. The lower part 36B of the flame 36 heats the thermostatic bulb 35 which opens the main burner valve 26. The pilot burner, Fig. 4, comprises a gas orifice 42, air inlets 46 and a tube leading to a downwardly open shield 50. The apertures 54, 65 and 62 for the small standby and large ignition flames are formed in the shield and have hoods 56, 64. The main burner valve 26 (Fig. 2) comprises a valve 112 co-operating with a valve seat 108 formed at the inlet end of a connector 110. The valve 112 is guided by a fixed pin 116 and is urged to a closed position by a spring 144 and is actuated by a pivoted lever 136 urged by a spring assembly 128 to close the valve. One end of the lever abuts a ball 132 welded to a head 134 secured to the outer of two diaphragms clamped together at their edges. A tube 72 extends from the pilot thermostatic bulb 35 to central apertures in the diaphragms and expansion of mercury in the tube and thermostatic bulb 35 forces the diaphragms apart and therefore moves the lever to open main gas valve 114. The tube 72 contains a rod to compensate for variations in ambient temperature. The spring 128 extends between a first disc abutting the lever 136 and a second disc abutting a second lever 150 which is adjustable by means of a screw 160. The spring 128 and levers 136 and 150 are so arranged that the force exerted on the valve is a maximum in the closed position. The connector 110 extends into a mixing tube 104 leading to the main burner and comprises a threaded upper portion 101 on which is screwed a connection 100 with an orifice 102 which discharges gas into the mixing tube 104. The upper end of the connection 100 has an internal conical bore 100F against which rests the conical end 100G of a jet piece 100B having side wings 100K and internal bores 100C and 100D. The main burner head has a series of gas orifices 66 around its side and these orifices may be slightly downwardly slanted along one side.