GB1066721A - Fuel injection systems for spark-ignition internal combustion engines - Google Patents

Abstract

1,066,721. Regulating I.C. engines. S.U. CARBURETTER CO. Ltd. Feb.24, 1966 [March 13, 1965; June 10, 1965], Nos.10741/65 and 24511/65. Heading F1B. In a spark ignition fuel injection engine the pressure differential across a fuel metering jet is modulated when a transient pressure charge occurs in the region between the choke and the throttle valve and the fuel supply is stopped when an abnormally high depression occurs in the air inlet manifold. Air enters via a variable choke 40 and passes through a valve 7 to manifold 1 which feeds inductor ports 3, 4, 5, 6 each of which is supplied by a fuel injection nozzle 8. Fuel from a liquid pump (not shown) passes through pipe 10, deaerator 9 and valve 18 to the primary chamber 12 of a pressure control unit 11. Diaphragm 14, which is loaded pneumatically with or without spring assistance, according to the pressure in region 15 acts through sliding spindle 17 to control valve 18 thereby maintaining a constant pressure difference between chambers 12, 13. Fuel passes through pipe 21 to a fuel metering jet 19 and thence via a pipe 20 to secondary chamber 13, pipe 22 and flow divider 23. The action of diaphragm 14 maintains a substantially constant pressure drop across the fuel metering jet 19. From the flow divider, which has an air vent 25 and a spring-loaded plunger 26, fuel is delivered through pipes 27, 28, 29, 30 to nozzles 8 each of which has a needle valve 31 mounted on an adjustably spring-loaded diaphragm 32. The outer side of diaphragm 32 is subjected to ambient pressure. The countoured needle 36 is moved by a suction-operated member 37 that controls the effective cross-sectioned area of choke 16 so as to maintain a substantially constant air flow. A transient pressure drop in region 15 e.g. on sudden opening of throttle 7, is communicated via a pipe containing a restrictor 50 to chamber 49 to increase the load applied by diaphragm 51 through pin 52 on diaphragm 14. A greater pressuredifferential is momentarily established between chambers 12, 13 and likewise across jet 19 thereby temporarily increasing fuel flow. To counteract the effect of pulsations when throttle 7 is fully opened a connection 46, 47 containing a restrictor 48 is arranged between manifold 1 and chamber 49. When an abnormally high pressure occurs in manifold 1 e.g. during overrun, the pressure is communicated through pipe 46 to act on a snapaction diaphragm 58 which actuates a pivoted lever 60 to close fuel admission valve 18. A sealed temperature/pressure responsive capsule 62 is linked through link 65 and rod 17 to diaphragm 14 to effect compensation for varying temperature and/or pressure.