Operating an engine includes injecting one or more early pilot shots of a liquid fuel containing methanol (MeOH) into a cylinder in an engine, and moving a piston in the cylinder from a bottom-dead center position toward a top-dead center position. Operating an engine further includes forming hydrogen peroxide (H.sub.2O.sub.2) in the cylinder from the MeOH of the early pilot shots, injecting a main shot of a liquid fuel into the cylinder, and hastening combustion of the liquid fuel of the main shot in the cylinder via hydroxyl (OH) radicals formed from dissociation of the H2O2. Injection of the one or more early pilot shots at appropriate crank angle timing(s) associated with suitable temperature ranges may promote desired reaction pathways according to a medium temperature combustion regime.

A control system of a compression-ignition engine is provided, which includes an engine configured to cause combustion of a mixture gas inside the combustion chamber, an injector attached to the engine and configured to inject fuel into the combustion chamber, a spark plug disposed to be oriented into the combustion chamber and configured to ignite the mixture gas inside the combustion chamber, and a controller connected to the injector and the spark plug and configured to operate the engine by outputting a control signal to the injector and the spark plug, respectively. After the spark plug ignites the mixture gas to start combustion, unburned mixture gas combusts by self-ignition. The controller outputs the control signal to the injector so that a fuel injection timing is advanced when the engine operates at a high speed than at a low speed.

A method of controlling a fuel injection of a diesel engine for performing a plurality of fuel injections to cause a plurality of combustions inside a cylinder in one combustion cycle, is provided, which includes acquiring an oxygen concentration inside the cylinder, performing, on compression stroke, the plurality of fuel injections at substantially even injection intervals while increasing the injection intervals as the oxygen concentration decreases, and performing, after the plurality of fuel injections, another fuel injection including a larger injection amount than in the plurality of fuel injections, near a top dead center of the compression stroke.

A method of controlling a fuel injection of a diesel engine for performing a plurality of fuel injections to cause a plurality of combustions inside a cylinder in one combustion cycle, is provided, which includes performing, on compression stroke, the plurality of fuel injections at substantially constant injection intervals while increasing an injection amount as an in-cylinder oxygen concentration decreases, and performing, after the plurality of fuel injections, another fuel injection including a larger injection amount than in the plurality of fuel injections near a top dead center of the compression stroke.

A microcomputer is configured to: calculate, the drive period of a previous injection, an injection interval, and an uncorrected target drive period for a current injection; obtain a correction period by increasing an internal variable from zero in proportion to the drive period of the previous injection during this drive period, attenuating the internal variable at a first-order delay during the injection interval, dividing the internal variable by a coefficient of the proportion at a start time point of the present current supply, and setting a result of the division as the correction period; and set a period obtained by subtracting the correction period from the uncorrected target drive period as a current drive period, to thereby supply a signal indicating the current drive period to the injector via a driver.

A method for determining at least one injection parameter of an internal combustion engine, including the following steps: detecting a pressure profile in a time-resolved manner in an injection system of an internal combustion engine at least during an injection; providing a reference pressure profile for at least one operating point of the injection system; comparing the detected pressure profile with the reference pressure profile, and ascertaining at least one injection parameter as a function of the comparison.

A control device for an internal combustion engine includes a fuel injector configured to inject fuel, a pressure increasing device that is provided upstream of the feel injector and is configured to increase the pressure of fuel supplied to the fuel injector, and an electronic control unit. The electronic control unit is configured to calculate an actual fuel injection amount based on a difference between a fuel pressure in the fuel injector in a case where the pressure increasing device increases the fuel pressure without fuel injection by the fuel injector and a fuel pressure in the fuel injector in a case where the fuel injector performs fuel injection according to the driving of the pressure increasing device.

A method for operating an injection valve by determining an opening or closing time of the injection valve based on a sensor signal. The method includes: providing an evaluation point time series by sampling a sensor signal of a sensor of the injection valve; using a non-linear data-based first sub-model to obtain a first output vector based on the evaluation point time series, wherein each element of the first output vector is associated with a specific time; using a linear, data-based second sub-model to obtain a second output vector based on the evaluation point time series, wherein each element of the second output vector is associated with a specific time; limiting the time determined by the first output vector depending on the second output vector in order to obtain the opening or closing time.

A method for training a data-based evaluation model to determine an opening or closing time of an injection valve based on a sensor signal. The method includes: measuring an operation of the injection valve in order to determine at least one sensor signal and an associated opening or closing time; sampling the sensor signal at a sampling rate in order to obtain a sensor signal time series with sensor signal values; determining a plurality of training data sets by assigning a plurality of evaluation point time series generated from a sensor signal time series to the opening or closing time associated with the sensor signal, wherein the evaluation point time series has a lower temporal resolution than the sensor signal time series; training the data-based evaluation model depending on the determined training data sets.

Provided are methods and fuel injection systems implemented with a plurality of injectors coupled with a common rail, the common rail coupled with a pressure sensor, and the pressure sensor coupled with a processor. The method includes: identifying, by the processor, one of the injectors to calculate a pressure change rate of the common rail associated therewith; receiving, by the processor, pressure measurements of the common rail from the pressure sensor before and during an injection event within a measurement window; using, by the processor, a pre-injection mean pressure of the common rail to determine a rail pressure drop range that is specific to the identified injector; and calculating, by the processor, the pressure change rate associated with the identified injector based on the pressure measurements of the common rail taken during the rail pressure drop range.