A control device for a compression-ignition engine is provided, which includes an engine having a plurality of cylinders, spark plug, a fuel injector, and a control unit connected to the spark plug and the fuel injector. The control unit causes the engine to perform an all-cylinder operation when the engine operates at a load above a given load, and perform a reduced-cylinder operation at a load below the given load. In the reduced-cylinder operation, the fuel injector injects fuel to one or some of the cylinders to generate mixture gas, the spark plug ignites the mixture gas, and the engine starts, at an air-fuel ratio larger than a stoichiometric air-fuel ratio and a large compression ratio, SI combustion in which the mixture gas is ignited to combust by flame propagation, and then perform CI combustion in which unburned mixture gas ignites by self-ignition.

A first engine fuel, for example diesel fuel, is reformed (preferably via steam reforming) to produce syngas for use as a second engine fuel, with the fuels then both being used in an internal combustion engine to perform Reactivity Controlled Compression Ignition (RCCI). The syngas is produced and supplied to the engine as a supercritical fluid, thereby avoiding the pumping losses that would occur if syngas was pressurized for supply/injection. The reforming is done by a reformer which is provided as a unit with the engine (e.g., both the engine and reformer are onboard a vehicle), thereby effectively allowing use of a single fuel for RCCI engine operation.

Premixed engines have ignition issues when engine speed and load are below a predetermined range. An ignition apparatus for igniting a premixed charge in a gaseous-fueled internal combustion engine comprises an ignition device associated with a combustion chamber of the internal combustion engine. There is at least one of a dilutant injector for introducing a diluting agent that forms a stratified charge around the ignition device and an enrichment injector for introducing gaseous fuel that forms a stratified charge around the ignition device. An electronic controller is operatively connected with the ignition device and the at least one of the dilutant injector and the enrichment injector and programed to at least one of actuate the dilutant injector to introduce the diluting agent when the ignition device decreases a local air-fuel equivalence ratio around the ignition device below a predetermined threshold; and actuate the enrichment injector to introduce the gaseous fuel to decrease the local air-fuel equivalence ratio when engine load and engine speed are below a predetermined threshold engine load and speed range and when the ignition device does not affect the local air-fuel equivalence around the ignition device.

A control device for a compression autoignition engine includes an engine, a state quantity setting device, a spark plug, a controller, and a sensor. The spark plug receives a control signal from the controller and ignites air-fuel mixture at predetermined ignition timing such that the ignited air-fuel mixture is combusted by flame propagation and then unburned air-fuel mixture in a combustion chamber is combusted by autoignition. The controller outputs a control signal to an injector such that preceding injection and succeeding injection are performed in a compression stroke.

An engine device including an intake manifold configured to supply air into a cylinder; an exhaust manifold configured to output exhaust gas from the cylinder; a gas injector which mixes a gaseous fuel with the air supplied from the intake manifold; and a main fuel injection valve configured to inject a liquid fuel into the cylinder for combustion. At the time of switching from a gas mode in which the gaseous fuel is supplied into the cylinder to a diesel mode in which the liquid fuel is supplied into the cylinder, a supply-start timing of the liquid fuel is delayed relative to a supply-stop timing of the gaseous fuel.

A controller includes a valve control unit and a target calculation unit. The valve control unit is configured to control a fuel injection valve such that divergence decreases between an ignition delay of fuel injected into a cylinder through main injection and an ignition delay target value. The target calculation unit is configured to calculate the ignition delay target value such that the ignition delay target value decreases as estimated ignitability of the fuel in the cylinder increases during an engine operation in a region where diffusion combustion and premix combustion are both performed, the ignitability of the fuel in the cylinder being estimated based on a parameter that varies the ignitability.

A control device for a compression ignition engine is provided. At least in a high-load range where an engine load is higher than a given value, among an operating range where a partial compression ignition combustion is performed, an EGR valve is opened, and a first injection in which fuel is injected at least from an intake stroke to the first half of a compression stroke is carried out. While an engine body is operated in the high-load range, when a torque down request and a request for reducing external EGR gas amount introduced into the cylinder are issued, the opening of the EGR valve is reduced, and a second injection in which fuel is injected in the second half of the compression stroke is carried out, and a ratio of a fuel amount of the second injection to the total fuel amount injected in a combustion cycle is increased.

A control device for an engine is provided, which includes a combustion controlling module, and an ignition retard determining module configured to determine whether there is a request for an ignition retard for retarding an ignition timing of an ignition plug. When the controlling module controls the ignition plug and an injector so that the SPCCI combustion is performed and there is not the ignition retard request, the controlling module executes a control in which the entire fuel to be injected in one cycle is injected in an intake stroke and a jump-spark ignition is carried out at a basic ignition timing, and when there is the ignition retard request, the controlling module executes a control in which an injection is performed in an intake stroke, a portion of the entire fuel is injected in a compression stroke, and the ignition timing is retarded from the basic ignition timing.

A method of operating a dual-fuel combustion system includes reciprocating a piston between a bottom dead center and a top dead center of a cylinder, the piston including a piston bowl, a circumferentially extending recess located radially outside of the piston bowl, and a plurality of diverters in the recess. The method includes opening an intake valve to introduce a first fuel, and injecting, by a set of fuel injector orifices substantially aligned with the diverters, a second fuel toward the diverters. The method also includes autoigniting the second fuel to ignite the first fuel.

A method of operating a dual-fuel combustion system includes reciprocating a piston between a bottom dead center and a top dead center of a cylinder, the piston including a piston bowl, a circumferentially extending recess located radially outside of the piston bowl, and a plurality of diverters in the recess. The method includes opening an intake valve to introduce a first fuel, and injecting, by a set of fuel injector orifices substantially aligned with the diverters, a second fuel toward the diverters. The method also includes autoigniting the second fuel to ignite the first fuel.