GB663532A - Improvements in or relating to fuel supply systems for internal combustion engines - Google Patents

Abstract

663,532. Spray carburetters; regulating. BENDIX AVIATION CORPORATION. April 23, 1948 {April 30, 1947], No. 11259/48. Classes 7(iii) and 7(vi) A fuel metering device comprises a pair of metering orifices in parallel, means maintaining a metering head across the orifices as a function of engine speed, a single metering element responsive to intake manifold pressure controlling both orifices, and a valve means selectively directing the flow of fuel through one or both orifices, the valve means being controlled by a plurality of elements selectively rendered. effective in response to the actuation of controls for changing the operating conditions of the engine. In Figs. 1 and 2 fuel from the metering device 10 flows through a pipe 55 and filter 105, Fig. 3, to a chamber 106 for injection through a nozzle 108 into the air induction passage 09, and antidetonant, e.g. water may be fed by a pump 159 through a metering device 150, Figs. 1 and 3, to the chamber 106 for injection with the fuel. The device 10 may be set to meter over a rich or a lean fuel-air ratio curve, and a derichment valve 66 is closed when the antidetonant device is operating. In Fig. 1 an auxiliary supercharger (not shown) delivers air through the induction passage 109 to a main supercharger 124 which produces a boost pressure in the manifold 122, connected by pipes 123 to the cylinders 121 of a radial engine 120, which pressure is controlled by a variable datum boost control device 219. The fuel metering device 10, Fig. 2, comprises an engine driven pump 13 delivering fuel under pressure into a governor chamber 21 from which it flows through an orifice 31, controlled by a valve 29, to an unmetered fuel pressure chamber C and then through metering orifices 60, 61 in parallel to the metered fuel pressure chamber B leading to the pipe 55. The valve 29 is controlled by a centrifugal governor 34 driven from the pump, 13, and by a diaphragm 40 subject to the metering pressure across the orifices 60, 61, and a constant pressure drop is maintained across the orifice 31 by a byepass valve 46 carried by a spring-loaded diaphragm 47 subjected to the pressure in chamber C transmitted through passages 50<SP>1</SP>, 50 to the chamber 48, the valve 46 returning excess fuel from chamber 21 to the suction side 11 of pump 13. The main metering orifice 60 is controlled according to intake manifold pressure and exhaust back pressure (or atmospheric pressure) by a needle 96 actuated by capsules 100, 103, an extension 98 thereof controlling the orifice 61 to which fuel flows through a byepass 63, 63<SP>1</SP> containing a derichment valve 66 carried by a diaphragm 68 which loosely abuts against a second diaphragm 70. A switch 8, Fig. 1, may be closed to energize an electromagnet 79, Fig. 5, whereby a valve 76 is raised to transmit fuel pressure from the chamber 21 through passage 86<SP>1</SP> to the space 71, Fig. 2, to close the valve 66, fuel being then metered only through orifice 60 to give a lean fuel-air ratio curve. If the boost pressure rises above a valve which would cause detonation when operating on the lean curve a switch 230, Fig. 1, is opened by a bellows 231 subject to the boost pressure, de-energizing the electromagnet 79 to allow the .valve 66 to open to enrich the mixture. With the switch 8 opened, the valve 66 remains open for operation on a rich fuel-air ratio curve. A valve 90, Fig. 2, actuatedby a thermometric bulb 94, Fig. 1, in the air intake pipe controls a second byepass 91 to provide a correction for temperature. Closing of a switch 161, Fig. 1, operates a pump 159 to supply antidetonant through a filter 158 to a chamber 153, Fig. 3, the increase in pressure in which opens a valve. 190 through which the antidetanant pressure is transmitted by a pipe 194 to a chamber 74, Fig. 2, to close the derichment valve 66, and by a pipe 194' to actuate a piston 206, Fig. 1, to close a switch 208 which energizes a solenoid 215 to open a bleed valve 216 in the boost control device 219, whereby the boost pressure is increased. From chamber 153 the antidetonant flows through a poppet valve 163 to a metering valve 176 and then through a check valve 185 to the chamber 106 for injection with the fuel through nozzle 108 the valve 111 of which is carried by a spring-loaded diaphragm 113 subject to the pressure upstream of the throttle valve 110'. The valve 163 is carried by a diaphragm 170 subject to the pressure drop across the metering valve 176 which is controlled by a capsule 180 subject to the pressure in the induction passage 109. The throttle valves 110, 110<SP>1</SP> are simultaneously actuated by a link 136, Fig. 3, which is also connected to a lever 135<SP>1</SP> actuating an accelerating pump 130 which delivers through check valve 143 into the chamber 106. A valve 52, Fig. 2, cuts off the fuel when the engine is stopped and also disconnects chamber 48 from the chamber C. Specification 680.756 is referred to. Reference has. been directed by the Comptroller to Specification 680,756.