Abstract: The individual cylinder air to fuel ratio of an internal combustion engine varies due to the fact that the intake manifold cannot distribute airflow into the individual cylinders evenly. This feature of the present invention utilizes minimum timing for best torque MBT timing criterion provided by the ionization signals or by the in-cylinder pressure signals to balance the air to fuel ratios of the individual cylinders. The control method of the present invention comprises: calculating a mean timing coefficient, calculating a timing coefficient error, integrating the minimum timing for best torque timing coefficient error, calculating a raw fuel trim coefficient, resealing the raw fuel trim coefficient, updating a feedforward look-up table based upon the current engine operating conditions, and calculating a final fueling command.

Abstract: This feature of the present invention comprises a closed loop which uses estimated MBT timing criteria and ignition diagnostics (knock, partial-burn, and misfire) to control engine ignition. When the engine is not knock limited, it operates at its MBT timing. When the engine is knock limited, the engine runs at its inaudible knock limit. When the engine is misfire/partial-burn limited, the engine is maintained at its misfire/partial-burn limit. Three different embodiments of the closed loop MBT timing control architecture are disclosed: a cylinder-by-cylinder control, an average control and a mixed control.

Abstract: The present invention is directed to a dual charge rate power supply circuit and method for ionization detection. The circuit includes a first diode, first and second capacitors, and first and second current paths. The first diode includes an anode operably connected to a first end of a primary winding. The first capacitor has a second end operably connected to ground and the second capacitor has a first end operably connected to the cathode of the first diode as well as a second end operably connected to ground. The first and second current paths are operably connected between the first and second capacitors and include a second diode, a parallel combination of a first resistor and a third diode, and a second resistor. The first diode is operably connected in parallel with the first capacitor.

Abstract: The present feature of the invention is generally directed to a subsystem of an ignition diagnostics and feedback control system using ionization current feedback. It utilizes the ionization signal from an ionization detection circuit to monitor ignition parameters, such as primary charge timing, primary charge duration, ignition/spark timing, and ignition/spark duration for future “smart” ignition system control. In addition, the ionization signal is also used to detect spark plug carbon fouling, as well as plug insulator overheating. These parameters can be monitored for every cylinder of the engine for each engine cycle.

Abstract: This feature of the present invention comprises a method and apparatus to reduce NOx emissions in an internal combustion engine. This feature of the present invention uses a closed loop control of the exhaust gas re-circulation to provide the engine with the either EGR MBT timing or a knock limited timing to yield the minimum NOx emission with maximum fuel economy benefits associated with exhaust gas re-circulation. When the exhaust gas re-circulation rate is not knock limited, the engine sets its exhaust gas re-circulation rate to an optimal rate at which the engine runs at the exhaust gas re-circulation minimum best time for best torque spark timing limit. When the exhaust gas re-circulation rate is knock limited, the engine sets its exhaust gas re-circulation rate to a knock limited rate at which the engine runs at a retarded MBT spark timing limit. The engine uses calibratable MBT timing criteria to determine the retarded MBT spark timing limit.

Abstract: The present invention provides a system and method for controlling the retard limit of an engine having one or more cylinders in which combustion occurs. A sensor is employed to detect the ionization of the combustion process in the cylinders. The ionization is related to a retard limit feedback, and the sensor further transmits a signal associated with the retard limit feedback. A controller relates the retard limit feedback signal to a metric, monitors the stochastic behavior of the metric, and adjusts the ignition timing of the engine in response to the stochastic behavior to operate the engine below a retard limit target.

Abstract: A circuit for measuring ionization current in a combustion chamber of an internal combustion engine including an ignition coil, having a primary winding and a secondary winding, and an ignition plug. The ignition plug ignites an air/fuel mixture in the combustion chamber and produces an ignition current in response to ignition voltage from the ignition coil. A capacitor, charged by the ignition coil, provides a bias voltage producing an ionization current after ignition of the air/fuel mixture in the combustion chamber. A current mirror circuit produces an isolated current signal proportional to the ionization current. In the present invention, the ignition current and the ionization current flow in the same direction through the secondary winding of the ignition coil. The charged capacitor operates as a power source and, thus, the ignition current flows from the charged capacitor through the current mirror circuit and the ignition coil to the ignition plug.

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: The present invention provides a system for controlling knock in an engine having one or more cylinders in which combustion occurs. The system includes a sensor that detects the ionization of the combustion process in the cylinders. The ionization is related to the knock intensity occurring in the cylinders, and the sensor further transmits a signal associated with the knock intensity. The system further includes a controller that monitors the stochastic behavior of the ionization signal and adjusts the ignition timing of the engine to operate the engine with an actual knock intensity that is below a knock borderline limit that defines a desired knock intensity.

Abstract: 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 M1C4827 EL driver is used in the charge pump circuit.

Abstract: The present invention includes an engine diagnostic method and routine, wherein a method of using an ionization signal to perform an engine diagnostic routine includes the steps of detecting the ionization signal; integrating the ionization signal over a first sampling window to generate a first integration ionization value; detecting a peak of the ionization signal over said first sampling window to generate a first peak ionization value; integrating the ionization over a second sampling window to generate a second integration ionization value; detecting a peak of the ionization signal over a second sampling window to generate a second peak ionization value; and diagnosing the engine using said ionization signal.

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: A circuit for measuring ionization current in a combustion chamber of an internal combustion engine including an ignition coil, having a primary winding and a secondary winding, and an ignition plug. The ignition plug ignites an air/fuel mixture in the combustion chamber and produces an ignition current in response to ignition voltage from the ignition coil. A capacitor, charged by the ignition coil, provides a bias voltage producing an ionization current after ignition of the air/fuel mixture in the combustion chamber. A current mirror circuit produces an isolated current signal proportional to the ionization current. In the present invention, the ignition current and the ionization current flow in the same direction through the secondary winding of the ignition coil. The charged capacitor operates as a power source and, thus, the ignition current flows from the charged capacitor through the current mirror circuit and the ignition coil to the ignition plug.

Abstract: This feature of the present invention comprises a method and apparatus to retard the spark time. As a result, the catalyst heats up quickly during the cold start. The retard spark control method of the present invention uses a closed loop to adjust the engine retard limit during an engine cold start to retard the engine spark as much as possible without engine misfire and with minimum partial burn. The increased exhaust temperature heats up the catalyst more quickly than conventional open loop approaches, which as a result, reduces hydrocarbon emissions. The closed loop retard spark control using ionization current feedback consists of four major components or functions, an error and gain generator, a proportional and integration control processing block, a default spark timing processor, and an adaptive learning apparatus.

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: 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: This feature of the present invention comprises an ignition diagnostics and feedback control system based upon detected ionization current in an individual cylinder. The system is divided into two subsystems: an ignition diagnostics subsystem and an ignition feedback control system subsystem. The ignition diagnostics subsystem comprises an ignition system diagnostics, a misfire detector, a knock detector, and a robust multi-criteria minimum timing for best torque MBT timing estimator. The ionization feedback control subsystem comprises five main subsystems: a closed loop cold start retard spark control using ionization feedback, a closed loop MBT timing control using ionization feedback, a closed-loop individual cylinder air to fuel ratio balancing control system, an optimal wide open throttle air/fuel ratio control, and an exhaust gas control using a spark plug ionization signal.

Abstract: The individual cylinder air to fuel ratio of an internal combustion engine varies due to the fact that the intake manifold cannot distribute airflow into the individual cylinders evenly. This feature of the present invention utilizes minimum timing for best torque MBT timing criterion provided by the ionization signals or by the in-cylinder pressure signals to balance the air to fuel ratios of the individual cylinders. The control method of the present invention comprises: calculating a mean timing coefficient, calculating a timing coefficient error, integrating the minimum timing for best torque timing coefficient error, calculating a raw fuel trim coefficient, resealing the raw fuel trim coefficient, updating a feedforward look-up table based upon the current engine operating conditions, and calculating a final fueling command.

Abstract: This feature of the present invention comprises a method and apparatus to reduce NOx emissions in an internal combustion engine. This feature of the present invention uses a closed loop control of the exhaust gas re-circulation to provide the engine with the either EGR MBT timing or a knock limited timing to yield the minimum NOx emission with maximum fuel economy benefits associated with exhaust gas re-circulation. When the exhaust gas re-circulation rate is not knock limited, the engine sets its exhaust gas re-circulation rate to an optimal rate at which the engine runs at the exhaust gas re-circulation minimum best time for best torque spark timing limit. When the exhaust gas re-circulation rate is knock limited, the engine sets its exhaust gas re-circulation rate to a knock limited rate at which the engine runs at a retarded MBT spark timing limit. The engine uses calibratable MBT timing criteria to determine the retarded MBT spark timing limit.

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.