Methods and systems are provided for re-combustion of exhaust in a cylinder of a multi-cylinder engine in order to increase the temperature of the exhaust for enhancing catalytic conversion within the multi-cylinder engine. In one example, a method may include expelling combusted gases from the cylinder into an intake manifold via an intake valve during an exhaust stroke, in order to rebreathe in the combusted gases from the intake manifold via the intake valve in a subsequent intake stroke.

A hybrid electric vehicle (HEV) for multiple operation modes includes: a gasoline diffusion flame (GDF) combustion engine configured to perform gasoline diffusion flame combustion; a motor-generator operatively connected to the GDF combustion engine and configured to selectively drive the HEV with electric power of a battery or generate electric power to charge the battery; and a multi-mode controller including a processor and configured to receive operating conditions of the GDF combustion engine and the motor-generator and define a plurality of mode operating regions based on the received operating conditions. In particular, the plurality of mode operating regions includes: an electric vehicle (EV) only mode operating region, a GDF mode operating region where the GDF combustion engine operates and drives the HEV while the motor-generator stops, and a GDF+EV mode operating region where the motor-generator assists the operation of the GDF combustion engine to drive the HEV.

Systems and methods regarding a ducted fuel injection (DFI) combustion system for an internal combustion engine can control an injection timing of a fuel injector to output fuel injections through at least one duct and into a combustion chamber of the internal combustion engine. The injection timing can include one or more pilot injections according to a predetermined range before top dead center (BTDC) for a combustion cycle; and a main injection into the combustion chamber for the combustion cycle after all of the one or more pilot injections. A first amount of the fuel injected for the main injection can be greater than a second amount of fuel injected for the one or more pilot injections. The predetermined range before top dead center (BTDC) of the one or more pilot injections can be from 85 to 40 degrees BTDC.

An engine management system and method may include a control system and method for controlling an internal combustion engine. The internal combustion engine may be a direct-injection engine using a Sonex Controlled Auto-Ignition (“SCAI”) combustion path. The control system and method may utilize fuel injection pressure, timing of start and end of injection, management of turbo airflow, fuel supplied, and other factors to provide reduced emissions and improved performance.

A system includes a fuel tank and a dehydration reactor that are configured to provide a primary fuel and a pilot fuel to a power system. The fuel tank is configured to store the primary fuel and is fluidly connected to a reactor feed line and a primary fuel line provide the primary fuel. The dehydration reactor is configured to receive the primary fuel via the reactor feed line and convert a portion of the primary fuel to the pilot fuel and a byproduct. The power system is configured to receive the pilot fuel from the dehydration reactor to initiate combustion of the primary fuel. The power system also includes a cylinder with an internal piston that receives the pilot fuel and the primary fuel, contains the combustion reaction, and generates power from the combustion reaction; and contains the combustion reaction. A pilot fuel injector provides the pilot fuel to the cylinder at a first time to initiate combustion and a primary fuel injector provides the pilot fuel to the cylinder at to generate power via the power system.

A dual fuel system includes a liquid pilot fuel supply, a liquid main fuel supply, and a fuel injection apparatus. The dual fuel system further includes a fueling control unit coupled with a cylinder pressure sensor and a NOx sensor, and structured to vary, via outputting a fueling control command to a main fuel injection control valve, fuel delivery parameters each on the basis of at least one of a cylinder pressure parameter or a NOx parameter. The fueling control unit compensates via the varying fuel delivery parameters for a change to a liquid main fuel composition such as a change from a first alcohol fuel or blend to a second alcohol fuel or blend.

Emission targets, such as NOx levels, for gaseous fuelled internal combustion engines that burn a gaseous fuel in a diffusion combustion mode are increasingly more challenging to achieve. A method of fuel injection for an internal combustion engine fuelled with a gaseous fuel comprises introducing a first amount of pilot fuel in a first stage of fuel injection; introducing a first amount of main fuel (the gaseous fuel) in a second stage of fuel injection; and introducing a second amount of main fuel in a third stage of fuel injection. The first and second amounts of main fuel contribute to load and speed demand of the internal combustion engine. Engine maps calibrated for different engine performance can be employed in different regions of the load and speed range of the engine. The engine maps are blended when the engine transitions between two regions; and momentary excursions into different regions do not change the engine calibration.

A method for operating an internal combustion engine, the method including the steps of: (a) actuating an injector to introduce a pre-injection amount of a fuel into a combustion chamber of the internal combustion engine; (b) determining, for an operating cycle of the combustion chamber in which the injector was actuated in the step (a), a pressure gradient characteristic value which is characteristic of a combustion chamber pressure gradient in the combustion chamber; (c) repeating the steps (a) and (b) a plurality of times; (d) determining a skew of a distribution of a plurality of pressure gradient characteristic values determined in the step (c); and (e) changing or maintaining an actuation of the injector depending on the skew determined in the step (d).

An internal combustion engine comprises a fuel injection valve which has a needle, wherein a valve opening speed of the needle during post injection is raised as compared with a valve opening speed of the needle during main injection if a pressure of the fuel is not more than a first predetermined pressure, while the valve opening speed of the needle during the post injection is lowered as compared with the valve opening speed of the needle during the main injection if the pressure of the fuel is not less than a second predetermined pressure that is a pressure larger than the first predetermined pressure, when a requested post injection fuel amount is larger than an injection amount threshold value.

A normal control unit performs a normal control to cause an injection apparatus to perform predetermined normal injection and subsequently cause an ignition plug to perform ignition. In a delay region in a combustion chamber, propagation of flame is retarded further than in another region when the normal control is performed. In a knock state, self-ignition occurs in the delay region when the normal control is performed. When the knock state is established, an adjustment control unit performs, to suppress the self-ignition, an adjustment control to perform main injection and subsequently perform sub-injection in a second half of a compression stroke to adjust a fuel distribution in the combustion chamber to facilitate propagation of flame to the delay region further than in the normal control and subsequently cause the ignition plug to perform the ignition.