Electric pulse generating apparatus for internal combustion engines

Claim 1

In combination with the ignition system of an internal combustion engine of the type having at least one piston moving in a cylinder and going through a position defining a ''''top dead center, '''' said piston imparting a rotation to a crankshaft, an apparatus for generating electric pulses said apparatus including: piston position detector means for delivering a first, variable duration voltage pulse during the interval when the piston moves between two predetermined positions, the duration of the voltage pulse being representative of engine speed, the end of said pulse substantially coinciding with the instant the piston goes through the top dead center in the cylinder; monostable circuit means coupled to said detector means and being responsive to the end of the variable duration pulse delivered by said detector for delivering a pulse of constant duration; first ramp generator circuit means connected to said monostable circuit means and being responsive to each said pulse of constant duration for delivering a second voltage pulse whose leading edge has a slope substantially proportional to the speed of rotation of said crankshaft driven by said piston, and whose trailing edge has a steep slope, said second voltage pulse being delivered during the interval of time when said detector delivers said first voltage pulse; second generator circuit means connected to the output of said monostable circuit means and responsive to said pulse of constant duration for producing a voltage having a level substantially inversely proportional to the speed of rotation of the crankshaft; voltage comparator circuit means connected to said first and second generator circuit means for comparing the values of the voltages delivered by said first and second generator circuit means, said comparator delivering a pulse when the voltage produced by said second generator means is lower than a value obtained by the voltage of the leading edge of the pulse delivered by said first generator means, the beginning of the pulse delivered by said comparator circuit means being coincident with equality between the value of the voltage of the leading edge of the pulse delivered by said first generator means and the value of the pulse delivered by said second generator means, the pulse delivered by said comparator constituting an energy controlling signal to control said engine ignition system; and means connected to said second generator circuit means and to said comparator circuit means for producing and for applying to the input of said comparator circuit means, for at least one predetermined value of the speed of rotation of said crankshaft, an auxiliary reference voltage of predetermined value replacing the voltage delivered by said second generator.