Operation timing control system for an internal combustion engine

Claim 1

An operation timing control system for an internal combustion engine comprising an engine shaft position transducer driven by the engine and producing a train of pulses each marking a specific angular position of the engine shaft, a fixed frequency clock pulse generator, a counter for counting pulses from the clock pulse generator, an empirically programmed digital read only memory having one set of input terminals connected to said counter, a further set of input terminals connected to a further transducer circuit associated with the engine, and a set of output terminals, an output circuit connected to the output terminals of the memory and a control circuit connecting the clock to the counter and the output circuit and also connected to the transducer whereby the counter is clocked by the clock pulse generator for a part of the cycle determined by the transducer and the output circuit is clocked by the clock pulse generator for another part of the operating cycle, characterised in that the control circuit includes a programmable frequency dividing circuit connected to the clock pulse generator and having divisor control input terminals connected to selective output terminals of the counter, whereby during said one part of the operating cycle the frequency at which the counter is clocked is varied in accordance with the count state of the counter and during said other part of the operating cycle the output circuit is clocked at a fixed frequency determined by the count state of the counter at the end of said one part of the operating cycle.