Patent GB-448534-A (GB)
Abstract: 448,534. Valves. JUNKERS & CO., GES., 35, Junkerstrasse, Dessau, Anhalt, Germany.-(Assignees of Bosch Akt.-Ges., R. ; 4, Militarstrasse, Stuttgart, Germany) March 2, 1935, No. 6624. Convention date, March 3, 1934. [Class 135] In a heating device or plant having a main burner, variations in a current of air led to a control flame, consequent upon variations in the supply of the air of combustion to the main burner, or in the supply of cold air to be treated in the plant, from one of which the current is derived, affect the control flame which in turn influences a heat-sensitive device adapted to vary the fuel supply to the main burner. In the compressed air burner, Fig. 1, a valve 21 controlling the passage of gas from a supply pipe 19 into a suction chamber 15 is controlled by a bimetallic strip 20 influenced by a flame 23 burning at the end of a narrow bore 22. The flame is caused to impinge on the strip 20 by air supplied from the main compressed air supply pipe 16 through a branch pipe 17 and a bore 18. Failure of the air or gas supplies causes the flame to leave the strip 20, and the valve to close. A reduced air supply causes the valve opening to be reduced accordingly. The pipe 17 may be replaced by a pipe branching from the mixing nozzle 24 and conducting a mixture of gas and air to the control flame. In Fig. 3, the heatsensitive expanding disc 20 is enclosed in a chamber 26 into which the branch air pipe 17 opens. With an adequate air supply, gas passing through a bore 22 burns at the disc and keeps the gas valve 21 open. When the air supply fails, the control flame 23 leaves the disc which therefore cools and closes the valve 21, and burns as a tell-tale flame at the orifice 28 ready to jump back to the disc on restoration of the air supply. A modification of this arrangement has an expanding tube with apertures for supplying gas to the control flames, enclosed in a larger tube to which the control air current is admitted. Any unburnt gas is consumed at an aperture in the top of this latter tube. Fig. 7 shows an air heater 41, the gas supply to the main burner 40 of which is controlled by a valve 44 connected to a diaphragm 43 to the control chamber of which gas is admitted by a small opening 46. When the blower 50 is in operation, the control chamber is maintained vented and the valve 44 open by a control valve 21 similar in operation to that in Fig. 3, and having a pipe 17 for leading a current of air to a chamber 49 enclosing the expanding diaphragm. To avoid re-ignition of the flame 23 by an operator when the valve 21 closes, gas is supplied to the casing 49 through the casing 48 of the valve 21 by pipes 51, 51<1> containing a safety cut-off device 21<1>, the name 23' of which immediately re-establishes the flame 23 if necessary and the valve of which cuts off the supply through the pipe 51 if the flame 23<1> is extinguished. If the blower 50 is replaced by a suction device, a small bore 52 enables an adequate supply of air for the control flame to be sucked through the casing 49 and pipe 17 at a predetermined degree of suction. The burner 53, Fig. 10, is fed from a compressed air injector 16, 24 which sucks air from a chamber 15 communicating with a vacuum-operated pressure regulating valve 54. The compressed air supply is regulated by a valve 57 having a control chamber 60 fed through a restriction in the control pipe 59 by a pipe 61. The control pipe 59 has two control valves, one, 63 operating in response to a working condition such as the temperature or pressure in a boiler, and the other 21 generally similar to the valves 21 in Figs. 3, 7. In this case however, the valve 21 controls the escape of air, gas being supplied by a pipe 51 connected to the inlet side of the valve 54. Failure of the air supply causes the disc 20 to contract and the valve 21 to close. The valve 57 then closes and since there is then no vacuum in the chamber 15, the gas valve 54 also closes. In another modification, the supply of fuel to an oil burner is controlled by a valve opened by gas pressure on a diaphragm. This independent gas pressure is controlled by a valve 21 as shown in Fig. 3, the control flame 23 of which projects into the flame chamber of the burner and forms an ignition flame. The casing corresponding to 26 is supplied with air from the air supply to the main burner. In most forms, the supply of air or gas can be increased so that a non-combustible mixture is formed, and the control flame is extinguished.