GB703113A - Improvements in or relating to carburettors for supplying fuels of different volatilities to internal combustion engines - Google Patents

Abstract

703,113. Spray carburetters. ALLDAY, G. J. Oct. 16, 1952 [Oct. 16, 1951], No. 24073/51. Class 7(3) In a carburetter provided with means for feeding different fuels, e.g. petrol and paraffin, to a valve chamber 16 provided with a valve 18 for selecting the fuel, each fuel feed means comprises both a main jet 19 for the main supply of fuel to the chamber 16 and a compensating jet 20 having an air passage 27 associated therewith whereby at certain pressure conditions in the carburetter a fuel-air mixture passes through the valve chamber 16 to the fuel nozzles 31, 36. As shown diagrammatically in Fig. 1, the petrol and paraffin from float chambers 13, 7 respectively pass through the main jets 19 into passages 29 leading into recesses 6, 6<1> in the valve chamber 16 and through the compensating jets 20 to aerating chambers 27 from which the aerated fuel flows through passages 28 into the passages 29 and thence into the chamber 16, which chamber communicates through a passage 30 with the main nozzle 31 and through either passage 42 or 43 with the idling nozzle 36. The valve 18 is actuated by a solenoid 17 in circuit with a switch 2, operated by a thermostat located for example in the engine cooling system, and a manually controlled switch 1. When the engine is cold the valve 18 closes the recess 6<1> and the passage 43 whereby petrol is supplied to the main nozzle 31 and, through the passage 42, to the idling nozzle 36. When the engine becomes warm, the solenoid 17 is energized to lift the valve 18 to cut off the petrol supply and open the paraffin supply, the idling fuel now flowing through passage 43. In both cases at small engine suction, e.g. at a speed slightly above idling, aerated fuel from the jet 20 is drawn into the chamber 16 but as the suction increases the aerated fuel is cut off by the flow of un-areated fuel from the jet 19. Air is bled into the idling fuel passage past a valve 38. One or more of the passages 29 may open into the cylindrical wall of the chamber 16, and a small clearance may be left between the periphery of the valve and the chamber wall so that when the valve obscures one of the passages 29 a small flow of fuel escapes therefrom past the edge of the valve. In a practical arrangement, Fig. 2, the valve chamber 16 is formed in a block 10 having flat faces 11, 12, fitting against similar faces on a block 9 containing the float chambers and on a block 14 containing the mixing chamber, and the solenoid 17 is arranged beneath the block 10. An overriding hand control is provided to move the valve 18 if the solenoid 17 becomes inoperative. Specification 644,721 is referred to.