Patent GB-938800-A (GB)
Abstract: 938,800. Controlling gas burners. ROBERTSHAW-FULTON CONTROLS CO. Aug. 2, 1960 [Aug. 14, 1959], No. 26765/60. Class 75 (1). [Also in Group XXIX] The gas supply to a main burner 16 heating an oven is controlled by a thermostatic valve 10 responsive to the temperature of the oven and also by a thermostatic safety valve 12 actuated by the flame of a pilot burner 132. The two thermostatic valves 10, 12 are in series. The gas supply to the pilot burner 132 is controlled by the first thermostatic valve 10 which comprises a valve disc 50 adapted to co-operate with a cup-shaped valve seat member 32 screwed into the valve casing and having an annular seat 40 and a pair of annular seats 46, 48 co-planar with the seat 40. The seat 40 controls the flow to the main burner 16 and the pair of seats 46, 48 control the flow to the pilot burner 132. The valve disc 50 engages the three seats simultaneously. Gas is supplied to the interior of the valve seat member 32 by a tapered plug valve 26 rotated by a knob 29. The rotation of the plug valve 26 is transmitted to the valve seat member 32 by a connector 30 and causes axial movement of the valve seat member to provide different oven temperatures. The valve disc 50 is connected to an expansible element 58 connected by capillary tubing 56 to a sensing bulb 54. The valve 10 is by-passed by an adjustable passage 72. The safety valve 12 comprises a valve 90 actuated by a pair of levers 104, 112 pivoted at 110 and 108 to a bracket 106. An expansible element 100, abuts an adjustable screw 102 carried by the upper lever 104 and is connected by capillary tubing 98 to a temperature-sensitive bulb 96 heated by the pilot burner. The main burner 16 has au adjustable air inlet 118. In operation, when the oven temperature rises above the temperature set by the knob 29 the thermostatic valve 10 cuts out both the pilot burner and the main burner simultaneously and the extinction of the pilot burner closes the safety valve 12. When the oven temperature drops the thermostatic valve 10 opens to supply the pilot burner. The pilot burner is ignited by a continuously burning pilot 126 and opens the safety valve 12 to supply the main burner. In a modification, Fig. 2 (not shown), the thermostatic valve 10 has two valve discs, spring-mounted on the same stem, one for controlling the supply to the pilot burner and the other the supply to the main burner and in operation the disc controlling the main burner closes before the disc controlling the pilot burner. The main burner is then supplied by the adjustable by-pass passage 72. In another modification, Fig. 3 (not shown), the pilot burner is supplied from the downstream side of the thermostatic valve 10 controlling the main burner and is not valvecontrolled. When the thermostatic valve 10 is closed the pilot burner is supplied through the by-pass 72. When the thermostatic valve disc 50 moves to restrict the flow to the main burner the pressure of gas to the pilot burner reduces and the pilot flame is too small to hold open the safety valve 12 which therefore closes to extinguish the main burner. The gas pressure therefore increases and enlarges the pilot flame so that the safety valve 12 again opens and the main burner is again supplied. The cycle then repeats. Specification 625,696 is referred to.