GB1334039A - Electronic fuel injection systems - Google Patents

Abstract

1334039 Electrical fuel injection systems for I C engines GENERAL MOTORS CORP 3 Aug 1972 [27 Aug 1971] 36234/72 Heading G1N In an I.C. engine intermittent fuel injection system, an inductive transducer 100 having an inductance variable with engine air intake pressure is charged and subsequently discharged in synchronism with engine rotation, the charging voltage determining the injection pulse duration in such manner that, when the engine speed is above a predetermined value, the amount of fuel injected decreases with increasing engine speed and with increasing intake air pressure. As shown, the inductive transducer 100 includes a coil 106 and a core 108 movable in dependence upon air intake pressure. A trigger pulse former 164 provides pulses in synchronism with engine rotation, each pulse causing the coil to be charged via resistors 102, 104 to provide a charging voltage A1, Fig.4, the slope of the voltage being determined by the resistances of resistors 102, 104 and the inductance of coil 106. When the voltage A 1 falls to a predetermined level L r ', a transistor 116 is rendered conductive and the coil 106 discharges via resistor 104 and the conductive transistor 116, to provide a discharge voltage As whose slope is determined by the resistance of 104 and the inductance of 106. An injection pulse C is provided during the voltage A 1 . Figs.4a and 4h represent the voltage diagrams which occur at two different speeds above the predetermined engine speed. As can be seen, at the higher speed, Fig.4b, the amplitude M 2 of the voltage A 1 above the reference level L' r is smaller than at the lower speed. This is due to the negative-to-positive voltage jump being of the same amplitude at all engine speeds, and a greater portion of the amplitude being below the reference level at higher speeds. Fig.4c represents the voltage diagram which occurs at the same speed as that represented in Fig.4b but at a higher intake pressure. In this case the slopes of the curves are shallower due to the increased inductance of the coil 106.