GB839994A - Improvements in or relating to an internal combustion engine charge forming device - Google Patents

Abstract

839,994. Spray carburetters. ACF INDUSTRIES Inc. March 28, 1957 [Jan. 7, 1957], No. 10151/57. Class 7(3) In a fuel supply system having fuel metering needles 23 controlled by a valve 37 which is actuated in accordance with air flow, means are provided to enrich the mixture ratio when the throttle valve 50 is opened. The valve 37 is actuated by a diaphragm 40 controlled by the pressures at points 44, 45, on opposite sides of the valve 37, and the metering needles 23, which control the flow from a chamber A, through pipes 24 to injection nozzles 29 in the intake branches 26a, are actuated from the shaft 36 of the valve 37 through a magnetic clutch 35. On opening of the throttle valve 50 a diaphragm 127, normally urged to the right by the suction transmitted through pipe 130, is released and urged to the left by spring 128 to compress air in a chamber 125 connected to chamber 41 whereby the diaphragm 40 is actuated to open valve 37 and move the needles 23 in a direction to increase the fuel supply. A lean fuel air ratio is maintained under part-throttle conditions by an air bleed 213 into the chamber 42 which reduces the suction in chamber 42 and thereby reduces the opening of valve 37 and needles 23 for a given intake pipe suction. The bleed 213 is controlled by a valve 212 actuated by the suction downstream of the throttle valve 50, the valve chamber 206 being connected by pipe 205 to inlets 202, 203. At small throttle openings the intake pipe suction acting in chamber 210 holds valve 212 open and if the valve 37 is only open a small amount air is bled through openings 202, 203, into chamber 42 to produce a lean mixture. At a predetermined opening of valve 37 the edge of the valve 37 is situated opposite or above the openings 202, 203, and the suction set up reduces or prevents flow of air through the bleed passage 213 and the mixture is enriched. Similarly when throttle valve 50 is opened wider the intake suction decreases and valve 212 closes to produce enrichment of the mixture. The chamber A is supplied by a pump P through a filter 21 and pressure control valve 22 and the diaphragms 28 carrying the fuel injection valves 29 are all loaded at the same pressure by a datum pressure line 56, 58, the pressure in which is maintained constant by a control valve 75 carried by a spring- loaded diaphragm 71, the outlet end of line 58 having a restriction 61, the pressure downstream of which is controlled by a diaphragm actuated valve 167. On closing of the starting switch S and partial depression of the accelerator pedal T, switches 181, 182, close contacts 183-186 to energize an electromagnet which rocks a magnetized lever 172 to lower the pivot 170 of a lever 169, whereby the valve 167 is opened wide causing a large pressure drop in the datum pressure line 58 so that the injection valves 29 are cpened wide to provide a very rich starting mixture, normal conditions being restored when the starting switch S is released. If the engine is flooded, depression of the pedal T to. wide open throttle position causes closing of the contacts 183, 186, 190, 191, which reverses the current through electromagnet 173 whereby the lever 172 is forced upwards to close valve 167, causing pressure to build up in line 58 and close the injection valves 29 so that turning over of the engine clears the cylinders. A bimetallic coil 102 opens valve 37 and metering needles 23 to provide a rich cold-starting mixture, the action of the coil being opposed after starting by a piston 105 actuated by intake pipe suction. A pressure relief valve 76 opens to a point downstream of restriction 61 to relieve any build-up in pressure in the line 58 caused during acceleration by the opening of the valves 29, the escaping fuel acting on diaphragm 164 to open valve 167. In a modification the datum pressure regulator C is situated downstream of the injection nozzles 25 and the pressure relief valve is connected to the pump intake pipe 19. In Fig. 4 the enrichment on acceleration is produced by a diaphragm pump 230 actuated directly from the throttle valve control by a rod 234, the pump acting to increase the suction in chamber 42 during throttle opening and thereby increase the opening of the valve 37 and the fuel metering needles. Specification 807,919 is referred to.