Patent GB-702925-A (GB)
Title: Improvements relating to oil burners
IPC: F23D11/10
Filed: 1951-03-27
Abstract: 702,925. Liquid fuel burners. RUTHERFORD, E. J. Y. March 26, 1952 [March 27, 1951], No. 7064/51. Class 75 (i) In an oil burner provided with a flash boiler for generating steam for atomising the oil and having auxiliary means for starting from co] d a thermostat is located to reach its operative temperature when the flash boiler is heated sufficiently to generate steam with the auxiliary starting means in operation and is arranged to control two valves for admission of oil to the burner and of water to the boiler so as to effect a change-over to normal operation. In the burner apparatus shown in Fig. 2 pressure air is used in place of steam to atomize the oil at starting. The pressure air passes through the flash boiler and is controlled by a poppet valve 21 ; the oil is controlled by a second poppet valve 23 ; and the feed water is controlled by a third poppet valve 22. The air and oil valves are opened at starting by a manually actuated shaft 27 having fingers 30, 31 engaging the stems of the air and oil valves. A bimetal coil 34 is located in a pocket 35 in the burner housing 10 and is connected by crank and push rod mechanism to a second shaft 28 having a finger 33 for opening the water valve 22 and a finger 32 for engaging the stem of the oil valve 23. After a peri od of five minutes from starting the thermostat is sufficiently heated to cause the water valve to open and to prevent the oil valve from closing. The first shaft 27 is then released to allow the air valve to close ; the oil is then atomized by the steam generated in the boiler. The end of the finger 31 is forked to clear the top of the finger 32. The first shaft 27 may be held in starting position by hook or pawl engagement with the thermostat mechanism and be released automatically when the thermostat operates. The oil flow is regulated by a valve 16. The burner nozzle is cleared by a rotatable handle 17. The flash boiler consists of three U-tubes connected in series. In another arrangement the flash boiler and the thermostat are heated at starting by gas burners and the thermostat when sufficiently heated closes a valve 44, Fig. 4, controlling the gas to the gas burners and opens a valve 54 controlling the oil to the oil burner and a valve 55 controlling the water to the boiler. The movement of the thermostat is transmitted through crank and pull-rod mechanism to a rocking shaft 49 having fixed thereon two cams 52, 53 for lifting the oil and water valves 54, 55 and having rotatably mounted thereon a cam 51 for lifting the gas valve 44. The cam 51 is rotated manually at starting to open the gas valve 44 by means of a lever 45 and when the shaft 49 is rocked to open the oil and water valves a lost-motion connection between the shaft and the cam 51 closes the gas valve, the lost-motion connection comprising a pin 61 on the shaft engaging with a peg 62 on the cam. An arm 56 extends from the shaft between two pegs 57 on an end bearing plate 58 and carries a weight 60 which moves through a dead-centre position as the valves open and close. In the event of flame failure a spring 48 rocks the shaft to close the oil and water valves. The gas burners are ignited by a pilot burner and an interlock, preventing the burners being turned on before the pilot, may be fitted. The three valves 44, 54, 55 are identical, each comprising a metallic bellows 63 fitting over the valve stem, a protective pad 67 at the base of the bellows for engagement with the cam and a fabric seated head controlled by a coiled spring. In a central heating system, Fig. 6, in which a desired temperature of circulating water, steam or room atmosphere is automatically maintained, gas burners 40 are used at starting to heat the flash boiler. A thermostat 73 responsive to the temperature of the circulating medium actuates through crank and rod mechanism a gas valve 71 and a water valve 72 and the change-over thermostat in the burner housing is connected by a tensile connection 77 to a weighted arm 56 controlling a second water valve 78 in series with the first. The pressure in the water supply pipe 79 between the second water valve 78 and the boiler tubes actuates an oil cut-off valve 80 and also a second gas valve 81, an increase in pressure opening the oil valve but closing the gas valve. On a call for heat the thermostat 73 opens the first gas valve 71 and the first water valve 72 and since the second water valve 78 is closed there is no pressure in the water supply pipe 79 and consequently the second gas valve 81 is open. The gas burners are ignited by the pilot burner and after five minutes the change-over thermostat in the burner housing opens the second water valve 78 and the pressure in the water supply pipe 79 opens the oil valve 80 and closes the second gas valve 81. The oil valve 80 and the second gas valve 81 comprise spring urged plungers actuated by metallic bellows disposed inside chambers to which water from the pipe 79 is admitted. Safety valves actuated by a fusible link located above the burner may be included in the oil, water and gas lines. The thermostats may be of the volatile fluid type with the vapour pressure passing through a capillary tube connected to a metallic bellows for operation of a valve.