Various methods and systems are provided for adjusting fueling to groups of cylinders of an engine based on individual cylinder knock sensor outputs. As one example, a system for an engine includes: a controller with computer readable instructions stored on non-transitory memory that when executed during operation of the engine cause the controller to: deliver natural gas and diesel fuel to a first group of cylinders at amounts that produce a common, first substitution ratio of natural gas; deliver natural gas and diesel fuel to a second group of cylinders at amounts that produce a common, second substitution ratio of natural gas; and change a makeup of each of the first group of cylinders and the second group of cylinders based on individual knock sensor outputs of each cylinder of the first group of cylinders and the second group of cylinders.

Provided is a state determination device for an internal combustion engine. The state determination device includes a storage device, and an execution device. The storage device stores mapping data that is data defining a mapping that outputs a determination result of a state of the internal combustion engine, by using an internal combustion engine state variable as an input. The execution device executes an acquisition process of acquiring the internal combustion engine state variable each time a crankshaft rotates by a specified angle, and a determination process of determining the state of the internal combustion engine based on an output of the mapping using the internal combustion engine state variable as an input. The execution device omits a part of the determination process performed each time the crankshaft rotates by the specified angle when a rotation speed of the crankshaft becomes equal to or higher than a predetermined threshold.

A method of controlling an air-fuel ratio in a pre-ignition (PI) situation, may include: monitoring, by a PI detector, whether PI occurs in a cylinder of a plurality of cylinders of an engine; and when the PI occurs in the cylinder of the plurality cylinders, controlling, by a controller, an air-fuel ratio of the cylinder in which the PI occurs to be smaller than a theoretical air-fuel ratio, and controlling an air-fuel ratio of a remaining cylinder of the plurality of cylinders in which PI does not occur to be larger than the theoretical air-fuel ratio.

In one aspect, an engine ignition apparatus for a natural gas engine may include a housing including a drive piston, a floating piston, a controllable hydraulic fluid chamber located between the drive piston and the floating piston, and an ignition chamber acted on by the floating piston, the ignition chamber having an outlet formed by a plurality of orifices, the outlet being in direct communication with a combustion chamber of the engine. In another aspect, an engine ignition apparatus for a natural gas engine may include, among other features, a controllable valve connected to a hydraulic fluid chamber, and configured to open and release a hydraulic fluid from the hydraulic fluid chamber, and to close. In still another aspect, a method for controlling an engine ignition apparatus for an engine includes, among other features, controlling a volume of a hydraulic fluid chamber of an ignition apparatus.

In one aspect, an engine ignition apparatus for a natural gas engine may include a housing including a drive piston, a floating piston, a controllable hydraulic fluid chamber located between the drive piston and the floating piston, and an ignition chamber acted on by the floating piston, the ignition chamber having an outlet formed by a plurality of orifices, the outlet being in direct communication with a combustion chamber of the engine. In another aspect, an engine ignition apparatus for a natural gas engine may include, among other features, a controllable valve connected to a hydraulic fluid chamber, and configured to open and release a hydraulic fluid from the hydraulic fluid chamber, and to close. In still another aspect, a method for controlling an engine ignition apparatus for an engine includes, among other features, controlling a volume of a hydraulic fluid chamber of an ignition apparatus.

A method for detecting a cylinder-specific combustion profile parameter value for an internal combustion engine is described. The method includes the following: (a) detecting a toothed encoder signal, (b) determining a cylinder-specific tooth time interval on the basis of the toothed encoder signal, (c) determining a cylinder-specific phase value on the basis of a Fourier transformation of a part of the toothed encoder signal corresponding to the cylinder-specific tooth time interval, (d) determining the combustion profile parameter value on the basis of the cylinder-specific phase value and a stored transfer function which represents a relationship between the combustion profile parameter and the phase value.

A state detection system for an internal combustion engine includes: a memory configured to store mapping data, the mapping data being data that defines a detection mapping, the detection mapping being a mapping between an input and an output, the input being a rotation waveform variable and a drive system rotation speed variable and the output being a value of a combustion state variable, and the detection mapping including a joint operation of the rotation waveform variable and the drive system rotation speed variable based on a parameter learned by machine learning; and a processor configured to execute an acquisition process and a determination process, the acquisition process being configured to acquire a value of the drive system rotation speed variable, the determination process being configured to determine whether or not the internal combustion engine is in a predetermined operating state.

A method and control unit for cylinder equalization of an internal combustion engine having at least two cylinders, and includes the following steps: Determination of exhaust gas back pressure values of the individual cylinders over at least two operating cycles, correlation of the exhaust gas back pressure values with the camshaft position and/or the operating cycle, determination of the exhaust gas back pressure maxima for each cylinder, comparison of the exhaust gas back pressure maxima between the individual cylinders and detection of differences, adjustment of the cylinder-specific charge quantities of fresh air and/or fuel. In addition, the invention relates to a controller for carrying out the method and a motor vehicle having such a controller. The method improves the previously known methods and makes them more efficient, especially with regard to the efficiency of the combustion process and thus also of exhaust-gas aftertreatment.

A state detection system for an internal combustion engine includes: a memory configured to store mapping data, the mapping data being data that defines a detection mapping, the detection mapping being a mapping between an input and an output, the input being a first waveform variable and a second waveform variable and the output being a value of a combustion state variable, and the detection mapping including a joint operation of the first waveform variable and the second waveform variable based on a parameter learned by machine learning; and a processor configured to execute an acquisition process and a determination process. The acquisition process acquires a value of the first waveform variable. The determination process determines whether or not the internal combustion engine is in a predetermined operating state.

A method for extracting characterizing features from an ion current trace retrieved from spark plugs of cylinders of an internal combustion engine, comprises the steps of: i. dividing the ion current signal into crank angle subintervals; 5 ii. calculating a measure of ion current in each crank angle subinterval; and iii. Performing a calculation on the measure of ion currents from different subintervals such that the result of the calculation is dimension free. Further it relates to a method of monitoring combustion processes where a plurality of ion current signals from a number of spark plugs (4A, 4B) are 10 retrieved and used in combination.