GB600780A - Liquid fuel burning apparatus - Google Patents

Abstract

600,780. Porous block burners. ANCHOR POST FENCE CO. June 7, 1945, No. 14447. Convention date, May 27, 1944. [Classes 75(i) and 75(iii)] [Also in Groups XIII and XXVIII] An oil burner suitable for heating aircraft comprises a heat resistant capillary mass 10 preferably of ceramic material, formed with air passages 12, Fig. 3, means for delivering fuel to be absorbed by the mass, means for forcing airthrough the passages and means for preheating the air so that the fuel will be absorbed by the heated air to form a combustible mixture. When the aircraft is grounded, combustion air is supplied by a blower 38, Fig. 1, through pipes 40, 42 to a pipe 44 which traverses a tube 34, Fig. 7, through which the combustion products pass to a vent 36, so that the air is preheated to a temperature between 190 ‹ F. and 330 ‹ F. before mixing with the oil. Primary air passes through the holes 12 which are preferably in the upper half of the block 10, and oil is entrained to mix with secondary air entering through vanes 18, Fig. 1. Convection air is supplied to the space surrounding the tubes 24, 30, 34 through which the combustion products pass so that it is heated by vanes 37 and may be fed through a pipe 50 to heat the aircraft. Liquid fuel is supplied by a pipe 54, Fig. 8, to a pump 56 driven through gearing 58 by a variable speed motor 60, the fuel then passing through a tube 62 to a float valve 64 which will close if the fuel rises high enough to wet the air passages 12. A tube 66 runs to a pressure switch 68 which will open the circuit to the motor 60 if the pressure rises too high. An igniter comprises a resistance wire 84, Fig. 3, connected at 88 to a conductive metal casing 74 in the block 10, so that when the ignition is turned on, the wire becomes hot and heats the casing 74 and part of the block 10 so that some of the oil is vaporised, the vapour being drawn through slots 90 to be ignited. A spark igniter may, however, be used with a light and volatile fuel. Fig. 10 shows how the system is operated. To start the burner, a wheel 112 is rotated counterclockwise through 120 degrees, wheels 116, 118 also being rotated through 120 degrees by this action, to lift a pin 126 up onto a cam surface 128 and close contacts 130, a pin 142 onto a surface 144 and close contacts 146, and a pin 158 onto a surface 160 to close contacts 162, 164. This completes a circuit from a motor 134 through wires 132, 138 to operate the blower 38, and another circuit through wires 132, 138, the closed contacts 146 and a wire 148 to energise a solenoid 150 and operate the igniter 84. The energisation of the solenoid closes contacts 154 so that current is supplied through wire 156, closed contacts 164 and a wire 166 to energise a solenoid 168 to hold an armature 174 and prevent the wheel 118 from moving, and also to supply current through a wire 176, and the whole length of a resistance 178 to operate the pump motor 60 at low speed. When the aircraft is in motion, a scoop may be provided to draw in air, and when the pressure reaches a predetermined value, a switch 140 is operated to disconnect the blower 38 and connect the wire 138 to a wire 184 so that current is supplied through this wire, contacts 162 to light a pilot bulb 188 and also passes through part of the resistance 178 so that the pump motor 60 supplies fuel at a higher rate. The wheel 118 is held by the solenoid 168, but a 30 degree play is provided between this wheel and the wheel 116, so that the wheel 116 may rotate clockwise through 30 degrees under the clockwork action of the wheel 112, this rotation taking about five minutes, at the end of which time the pin 142 drops off the cam surface 144. This closes contacts 180 and opens contacts 146, so that the solenoid 150 is de-energised, releasing contacts 154 and the igniter 84 is switched off. As the contacts 154 are open current is no longer supplied to the wire 156 through them, but it is now supplied through contacts 180 and wire 182 to compensate for this. A manual switch 100, and a temperature limit switch are provided and when either of these is opened, the solenoid 168 is de-energised and the wheels return under the clockwork action of wheel 112 so that the burner is switched off. A pump exciter button 190 may be provided so that when it is closed the resistance 178 is by-passed and fuel may be brought up rapidly to saturate the block 10. A switch 192 may also be provided which is adapted to be closed to bypass part of the resistance 178 if a battery 136 is used instead of the motor 134.