| 摘要 |
A fuel injection control system for an internal combustion engine utilizes a metering unit to continually monitor air flow-rate to the engine and provide a pulse width modulated (PWM) digital signal which has a duty ratio representative of the air flow-rate. The duty ratio is the "on" period of the PWM signal divided by the total cycle period, which period is not related to engine speed. A further electrical signal indicative of engine speed is derived from the vehicle ignition system and the two signals are processed with the aid of a digital processor to provide an injector operating pulse. The system thus avoids use of A/D convertors normally associated with digital processors in this field and has a fast response time at all engine speeds. A means of fuel enrichment for times of rapid throttle opening is also disclosed as well as means for disabling the fuel supply on over-run. The air flow meter comprises a continuously rotating drum (21) having a cut out which passes between a light source and photodetector which is axially displaced against spring 3 by the air flow. Magnetic Hall effect or varie- switched oscillators may be used. <IMAGE> |
