Device for initiating in particular the ignition of an internal combustion engine

Claim 1

Device for initiating, in particular the ignition of an internal combustion engine, said device comprising means for measuring the speed of rotation of the engine which comprise a disc for fixing to the shaft of the engine, a first sensor and a second sensor associated with the disc and offset from each other by a predetermined angle, a reference element carried by the disc and movable in front of the sensors, and means for initiating the ignition as a function of the measured speed of rotation, said means for measuring the speed of rotation further comprising a first programmable divider down-counter having an output and an input, a clock connected to said input for delivering thereto signals at a frequency f o , a first counting means connected to said output for counting the signals delivered by the programmable divider down-counter, the frequency f c of said signals delivered by the first programmable divider down-counter being equal to the frequency fo of the clock signals divided by the value of the angle β equal to the difference between 360° and the angle α of the offset between the first sensor and the second sensor, a first memory containing different values of ignition advance angles having an output and an address input, the first counting means being connected to said address input, a second programmable divider down-counting means connected to said output of the first memory for counting down the signals stored in the first memory at a frequency corresponding to one signal per angular unit of rotation of the disc and, at the end of the count down, producing a signal actuating said ignition initiating means.