ELECTRONIC FUEL INJECTION WITH MULTIVIBRATOR - with speed-dependent fuel quantity determined by air intake

摘要

Electronic fuel injection system for I.C. engine comprises an electromagnetic injector valve, a power transistor connected in series with the magnetising coil of the valve, and a control multivibrator connected to the input of the transistor. The multivibrator is switched on synchronously with crankshaft revolutions by one of the output pulses of a bistable frequency divider connected to the ignition system, with simultaneous opening of the valve, and is maintained in this state for a period depending on quantity of air intake so as to determine quantity of fuel injected. The multivibrator contains a charging current source and a discharge current source for a timing capacitor. For speed-dependent control of the pulses emitted by the multivibrator, it charging current source coats with a timing circuit with preset trigger duration, to progressively delay charging between idling speeds of 2,500 r.p.m. and 600 r.p.m.