A combustion 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, in a compression stroke, fuel is injected at specific timing at which a line obtained by extending an axis of each hole of the injector overlaps with a specific portion including an opening edge of a cavity in an upper surface of a piston.

A combustion 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, in a compression stroke, fuel is injected at specific timing at which a line obtained by extending an axis of each hole of the injector overlaps with a specific portion including an opening edge of a cavity in an upper surface of a piston.

A method for operating an internal combustion engine having an engine with a first number of cylinders and a second number of cylinders and a supercharger arrangement, wherein a charge air flow supplied to the engine is compressed by means of at least one compressor and at least one turbine is acted on by an exhaust gas flow discharged from the engine. In a main operating mode, the engine operates the first number of cylinders in two-stroke operation and the second number of cylinders in four-stroke operation. A scavenging gradient of the engine is greater for the cylinders operated in the two-stroke operation than for the cylinders operated in the four-stroke operation.

A combustion chamber structure for an engine includes a combustion chamber where SI combustion by spark ignition and CI combustion by self-ignition are conducted. A crown surface includes a cavity recessed to have a bowl-shape, and a pair of raised portions. The cavity includes a bottom portion which is a lower region of the recessed part, the bottom portion having an outer circumferential edge which is circular in a top view. With a height of the raised portion relative to a height position of a deepest portion of the cavity being represented as H1 and a diameter of an outer circumferential edge of the bottom portion of the cavity being represented as D, H1/D as a ratio of the height H1 of the raised portion to the diameter D of the cavity is set to be in a range of 0.05 or more and 0.36 or less.

A combustion chamber structure for an engine includes a combustion chamber where SI combustion by spark ignition and CI combustion by self-ignition are conducted. A crown surface includes a cavity recessed to have a bowl-shape; a pair of first raised portions having a mound-shape along a pent roof shape; and a second raised portion provided to protrude at a position orthogonal to a ridge extending direction of the pair of first raised portions. With a height of the first raised portion relative to a height position of a deepest portion of the cavity being represented as H1 and a height of the second raised portion being represented as H2, H1/H2 as a ratio of the height H1 of the first raised portion to the height H2 of the second raised portion is set to be in a range of 1.92 or more and 2.75 or less.

A control apparatus for a compression autoignition engine controls compression autoignition by ignition. The control apparatus includes an injector, a spark plug, and a controller. The controller controls the injector so that fuel is injected by a plurality of divided injections, and thereafter, outputs a control signal to the spark plug at predetermined ignition timing so that, by ignition, unburned air-fuel mixture combusts by autoignition. Control is performed so that, when load on the engine is high, an amount of fuel injected at later timing among the plurality of injections becomes larger than when the load is low.

A control apparatus for a compression autoignition engine controls compression autoignition by ignition. The control apparatus includes an injector, a spark plug, and a controller. The controller controls the injector so that fuel is injected by a plurality of divided injections, and thereafter, outputs a control signal to the spark plug at predetermined ignition timing so that, by ignition, unburned air-fuel mixture combusts by autoignition. Control is performed so that, when load on the engine is high, an amount of fuel injected at later timing among the plurality of injections becomes larger than when the load is low.

A control apparatus for a compression autoignition engine controls compression autoignition by ignition. The control apparatus includes an injector, a spark plug, and a controller. The controller controls the injector so that fuel is injected by a plurality of divided injections, and thereafter, outputs a control signal to the spark plug at predetermined ignition timing so that, by ignition, unburned air-fuel mixture combusts by autoignition. Control is performed so that, when load on the engine is high, an amount of fuel injected at later timing among the plurality of injections becomes larger than when the load is low.

A system and method is provided that introduces oil droplets into the combustion chamber of a lean burn natural gas engine via dedicated channels located in the cylinder head and a valve seat insert for providing multiple distributed sources of ignition in addition to the spark plug based ignition system.

A system and method is provided that introduces oil droplets into the combustion chamber of a lean burn natural gas engine via dedicated channels located in the cylinder head and a valve seat insert for providing multiple distributed sources of ignition in addition to the spark plug based ignition system.