Patent GB-615393-A (GB)
Title: Automatic oil burners of the oil pressure atomising type
IPC: F23D11/00
Filed: 1946-08-09
Abstract: 615,393. Liquid-fuel burners. GILBERT & BARKER MANUFACTURING CO. Aug. 9, 1946, No. 23697. Convention date, May 24. [Class 75 (i)] An oil burner for starting, running and stopping operations under thermostatic control, of the kind including an air supply fan mounted in a casing, a shutter mechanism for controlling a passage area for the flow of air to the combustion chamber when the fan is operating, and which may be adjusted manually for effecting a precise adjustment of the air flow during normal operation of the burner, an oil pump for supplying oil at a predetermined constant rate to the combustion chamber through an atomiser, a motor for driving said fan and pump, a centrifugal clutch for connecting the oil pump to its transmission drive upon the motor and fan attaining a high speed, and for disconnecting the oil pump when the speed of the motor and fan drops below said high speed, wherein automatically operated mechanism is provided for adjusting the passage area for the flow of air to the combustion chamber to ensure that the said passage area during the starting and stopping operation of the burner will be greater than the passage area, determined by hand adjustment, for the said flow during normal operation of the burner. An electric motor 1, Fig. 1, controlled by a thermostat T, drives through transmission 2 and air supply fan 3 and an oil supply pump 10. The fan 3 blows air through a conduit 5 to meet atomised oil ejected through a nozzle 6 connected to the pump 10 through pipes 11, 12 and a pressure regulating valve 13. The pump 10 operates at constant speed to pump from the supply 8 more oil than is necessary at the nozzle 6, the excess being by-passed by the valve 13 through the pipe 14. The ignition system comprises electrodes 61 adjacent the nozzle 6 and may be switched on and off with the motor. The air supply to the fan 3 is controlled by a shutter 24, Fig. 3, mounted in an extension 20 of the fan casing having air inlet ports 21. By manual rotation of a rod 35, in screw-threaded engagment with a nut 34 integral with the shutter 24, adjustment is effected of the size of the air inlet opening between the shutter rim and the casing rim 40. The rod 35 is held in its adjusted position by a spring 37. When the motor 1 is started the fan 3 draws in air around the rim of the shutter 24 and also through a central opening 41 in which is mounted a supplementary fan 25. Upon the motor 1 attaining a high speed a centrifugal clutch 33 is actuated to engage the driving portion of the transmission 2 with both the fan 25 and the oil pump 10, and the fan 25 operates to oppose the main fan 3 in its action of drawing in air through the opening 41, so that considerably less air is supplied to the combustion chamber. The centrifugal clutch may, alternatively, be combined with the supplementary fan 25, the outer clutch element being provided with fan blades. In a further alternative construction the fan 25 is replaced by a pair of cylindrical shutters 45, 48, Fig. 9, provided with slotted passages 46, 47, respectively, which are in registration when the centrifugal clutch is disengaged to provide additional air inlets to the fan 3. When the clutch is engaged the member 45 rotates with the driving transmission 2 whilst the member 46 is driven from the member 45 through a spring connection 51 which allows relative displacement between the members 45, 46, whereby the passages 47, 48 are closed. In a further construction the driving part of the clutch has a flange 58, Fig. 11, which replaces the fan 25 and is provided with openings 59 that are closed by flaps 60 when the motor 1 attains a high speed. In Fig. 7 a hydraulic mechanism is shown for varying the air inlet to the fan 3 upon engagement of the clutch. The shutter adjusting rod 35 is provided with a piston 55 operating in a cylinder 54 connected to the outlet of the pump 10, so that when the latter is started the piston 55 is driven to set the shutter 57 in position to provide a reduced air inlet to the fan 3. In the construction shown in Fig. 1A the shutter 24 is connected by the links 80, 81 of a centrifugal governor to the clutch 23, so that when the latter is engaged the shutter is drawn towards the fan 3, against the action of a spring 83, to a position predetermined by the manual adjustment of a stop 87<1> carried by the shutter adjusting rod 84. In the construction shown in Fig. 12, a shutter 62 is provided to control the air flow from the outlet of the fan 64 which has an unrestricted inlet. The fan 64 forces air into an annular chamber 66 from which it is directed by vanes 67 into the conduit 69 containing the oil atomizing nozzle 79. Movement of the shutter 62 to reduce the air flow during the normal heating period of the burner is effected hydraulically by the oil pressure at the outlet of the oil pump 65 on the engagement of a centrifugal clutch similar to that previously described.