Ignition timing device avoiding pinging during the functioning of an internal combustion engine

Claim 1

In an ignition timing device for an internal combustion engine, supplying an ignition signal for each cylinder staggered in relation to the top dead centre of the cylinder in question in accordance with at least one parameter, the set of parameters taken into consideration including the speed of rotation of the engine, this device being connected to a pinging detector comprising at least one vibration detector fixed on the engine and an electronic circuit designed to process the data supplied by the said detector to control the ignition timing, the said circuit taking the said data into account only in the angular window corresponding to that fraction of the cycle of each cylinder during which pinging can occur, the improvement comprising (a) means for deriving a threshold signal value on the basis of the data supplied by the said detector in the said angular window of a cycle of a cylinder, (b) comparison means for comparing the signal supplied by the vibration detector in the angular window of a subsequent cycle of said cylinder of the engine with said derived threshold value for the same cylinder of the engine, and (c) means responsive to the said comparison means for controlling a modification of the ignition timing if pinging has occurred in the cylinder in question, and wherein said means for deriving a threshold value is effective to derive said value solely on the basis of the data supplied by said vibration detector during the corresponding angular window of the last preceding cycle of the same cylinder.