Control trigger generating system, particularly to generate a trigger

Abstract

To simplify electronic fuel injection or ignition signal generation, a transducer is provided which is formed as a segmental element providing a first or starting pulse at a certain angular position of the crankshaft of the engine and a second or termination pulse when the crankshaft of the engine has moved through a predetermined angle. A frequency controllable oscillator, typically a voltage controlled oscillator (VCO) forming part of a phase locked loop (PLL) provides counting pulses to a first counter 12, the first counter counting from the start to a termination number and then providing the trigger signal. A second counter 13 is included in the PLL and counting pulses from the oscillator in the interval between the start and the termination signals, the count being compared with a number introduced in the PLL so that the frequency of the VCO will change with change of speed of the engine and the time when the first counter, as controlled by the frequency of the VCO, will have reached its predetermined count state will be controlled in dependence of the time interval during rotation of the shaft through the predetermined angle. A third counter 24 can be connected to the first counter 12 to introduce a number therein derived parameters of the engine, or in accordance with functional characteristics thereof to preset a number into the first counter 12 and thus modify the time of generation of the trigger pulse, the first counter then, preferably, being a reverse or down counter counting to 0 or null.