Abstract: Internal combustion engine (ICE) on-plug ignition coils with transistor drivers located in powertrain control modules (PCM) or other remote locations are prone to high electrical and magnetic interference (EMI) emissions and are subject to interference from other components due to long connecting wires. Ionization detection circuits have even greater sensitivity to EMI because of their very low signal current levels (mioroampere). The present feature of the invention integrates both the coil driver transistor and ionization detection circuits into the on-plug ignition coil. By placing the circuit on top or on the side of the coil, the connection distance from the circuit to the secondary winding is minimized. Thus, the circuit is less susceptible to electrical and electromagnetic noise.

Abstract: In this feature of the present invention a charge pump is used to supply current to the ionization detection circuit. To detect in-cylinder ions generated during the combustion process, a DC bias voltage needs to be applied. There are two ways to generate the DC bias: conventional DC power supply (large electronics) and capacitor charges by primary or secondary flyback voltage (high voltage capacitor). Typically, flyback voltage is used to charge the capacitor which supplies current to the ionization detection circuit. This necessitates the use of high voltage capacitors. Generally, ceramic capacitors are used. However, as temperature fluctuates, the board that the capacitor is mounted on can flex, causing the ceramic capacitor to crack. This invention proposes to use a high voltage charge pump to provide enough DC bias voltage for measuring ionization current. In a preferred embodiment, a model number MIC4827 EL driver is used in the charge pump circuit.

Abstract: In a first preferred embodiment, the present feature of the invention multiplexes both the ionization and driver current feedback signals into one signal, thus reducing cost and making coil packaging easier. The multiplexed signal first outputs the ionization detection signal and then replaces the ionization signal with the charge current feedback signal when the charge command Vin is enabled. In other words, the multiplexed feedback signal outputs the ionization feedback signal and switches to the charge current feedback signal when the charge command Vin is active. In a second preferred embodiment, the present feature of the invention comprises a method and apparatus to multiplex the ignition driver gate signal with both the ignition coil charge current feedback signal and the ionization signal, thus reducing the package pin count by two.

Abstract: This feature of the present invention comprises two embodiments of an integrated ionization detection circuit and ignition coil driver according to the present invention, an ASIC and a single electronic package. The apparatuses reduce the cost and complexity of an in-cylinder ionization detection system by combining like functionality into one ASIC or electronic module easing packaging constraints. In both embodiments, a current sink is used. The current sink removes noise in the form of voltage spikes. The voltage spikes are high voltage, but of short duration. The current sink prevents these spikes from turning on the IGBT. However, the current sink allows the IGBT command signal to pass. This feature of the present invention also comprises a switch whereby ionization current and coil primary current are multiplexed.

Abstract: Internal combustion engine (ICE) on-plug ignition coils with transistor drivers located in powertrain control modules (PCM) or other remote locations are prone to high electrical and magnetic interference (EMI) emissions and are subject to interference from other components due to long connecting wires. Ionization detection circuits have even greater sensitivity to EMI because of their very low signal current levels (microampere). The present feature of the invention integrates both the coil driver transistor and ionization detection circuits into the on-plug ignition coil. In a preferred embodiment, parts rated at 140 degrees centigrade are used in both the coil driver transistor and the ionization circuits which are located on the coil to address temperature and thermal shock concerns. Additionally, parts rated at 20 G are used in both the coil driver transistor and the ionization circuits to address vibration concerns.