CPC F02P 3/096 (2013.01) [F02P 17/12 (2013.01); F02P 2017/125 (2013.01); F02P 2017/128 (2013.01)] | 19 Claims |
1. An electronic control device to control an ignition coil of an internal combustion engine, the electronic control device comprising:
a high-voltage switch connected in series to a primary winding of a coil and configured to switch between a closed position and an open position;
a driving unit configured to:
control a closure of the high-voltage switch during a phase of charging energy into the primary winding;
control an opening of the high-voltage switch during a phase of transfer of energy from the primary winding to a secondary winding of the coil and during a phase of measurement of an ionization current subsequent to the phase of transfer of energy, wherein said ionization current is generated by ions produced during a process of combustion of a comburent-combustible mixture in a combustion chamber of a cylinder of the internal combustion engine by means of a spark generated by a spark plug in the phase of transfer of energy;
a bias circuit configured to generate said ionization current during the phase of measurement of the ionization current, wherein said bias circuit is connected in series to a second terminal of the secondary winding;
an integrating circuit interposed between the bias circuit and a reference voltage;
wherein said integrating circuit comprises an integrating capacitor connected in series to the bias circuit and connected between the bias circuit and the reference voltage, the integrating circuit comprising a connection in parallel of the integrating capacitor and of a Zener diode, the Zener diode having an anode terminal connected to the bias circuit and having a cathode terminal connected towards the reference voltage,
wherein said integrating capacitor is configured to:
in a case wherein a pre-ignition of the comburent-combustible mixture in the combustion chamber during the phase of charging occurs, pre-charge, during the phase of charging energy into the primary winding, to a value limited by the Zener voltage of the Zener diode directly from a further ionization current flowing through the secondary winding during the phase of charging, so as to measure a value of the integral of the ionization current which flows through the secondary winding during the phase of charging due to said pre-ignition;
in a case wherein the pre-ignition of the comburent-combustible mixture does not occur, maintain a charge state substantially constant during the phase of charging energy;
completely discharge towards a substantially null value by means of the current flowing through the secondary winding during the phase of transfer of energy from the primary winding to the secondary winding.
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