A control system for a compression-ignition engine is provided, which includes an engine configured to combust a mixture gas inside a combustion chamber by compression ignition, a fuel injector attached to the engine, a state function adjusting part attached to the engine and configured to adjust at least introduction of fresh air into the combustion chamber, a three-way catalyst provided in an exhaust passage of the engine, a wall temperature acquiring part configured to acquire a parameter related to a temperature of a wall of the combustion chamber, and a controller. A swirl flow is generated inside the combustion chamber to circle along the wall. When the wall temperature of the combustion chamber is below a given wall temperature, the controller sets an air-fuel ratio of the mixture gas substantially to a stoichiometric air-fuel ratio so as to remain within a purification window of the three-way catalyst.

A control system for a pre-mixture compression-ignition engine is provided, configured such that in a first combustion mode, the control unit controls the fuel injection valve to have a fuel amount within a mixture gas in an outer circumferential portion of the combustion chamber larger than in the center portion, the swirl generating part to generate a swirl flow in the outer circumferential portion, and the spark plug to ignite the mixture gas in the center portion. In a second combustion mode, the control unit controls the fuel injection valve to start a fuel injection on intake stroke so that the mixture gas is formed in the entire combustion chamber, the swirl generating part so that a swirl flow becomes weaker than in the first combustion mode, and the spark plug to ignite the mixture gas before CTDC.

A piston for an internal combustion engine includes a crown portion having a bowl that includes a plurality of protrusions. Each of the plurality of protrusions includes a first side surface and a second side surface. Other features including at least one ledge formed between protrusions in segments, and a generally flat, inward facing surface on the protrusions may also be used.

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.

In internal combustion engine, a fuel injector has a nozzle tip forming first and second pluralities of nozzle openings configured to inject respective pluralities of first and second fuel jets into a combustion chamber. The first fuel jets are directed between projections formed in a piston during a main injection, and the second fuel jets are directed towards the protrusions during a post injection. The protrusions are asymmetrical to redirect the first fuel jets.

A method for operating an internal combustion engine including a step of concurrently introducing at least two combustible fuel jets into a combustion chamber of an internal combustion engine. A first combustible fuel jet of the at least two combustible fuel jets is ignited at an ignition time point. In a first operating mode of the internal combustion engine a second combustible fuel jet which is different from the first combustible fuel jet of the at least two combustible fuel jets is ignited after the ignition time point.

A control device for an engine is provided, which includes a fuel injector attached to the engine, a spark plug disposed to be oriented into a combustion chamber, a swirl control valve provided in an intake passage, and a controller connected to the fuel injector, the spark plug, and the swirl control valve and configured to control the fuel injector, the spark plug, and the swirl control valve. The swirl control valve closes in a given operating state of the engine. The fuel injector injects fuel after the swirl control valve is closed, between intake stroke and an intermediate stage of compression stroke. The fuel injector injects the fuel after the first fuel injection. The spark plug performs the ignition after the second fuel injection so that the mixture gas starts combustion by flame propagation and then unburned mixture gas self-ignites.

An engine structure configured to a control swirl in a diesel engine combustion chamber and a diesel engine assembly including the engine structure defines first and second intake ports and a connecting passage connecting the first and second intake ports. The first intake port is in fluid communication with the combustion chamber and configured to direct a first intake airflow into the combustion chamber, and the second intake port is in fluid communication with the combustion chamber and configured to direct a second intake airflow into the combustion chamber. The connecting passage connects the first intake port to the second intake port and is defined by the engine structure outside of the combustion chamber.

A direct-injected compression ignition internal combustion engine includes an engine housing having a cylinder and a piston movable within the cylinder and including a piston end face forming a combustion bowl. The piston end face has an annular piston rim with a rounded inner rim surface that extends radially inward and axially downward from a planar outer rim surface to a combustion bowl edge. An antebowl is defined by the rounded inner rim surface and has an antebowl volume that is about 0.8% or greater of a total volume of the combustion bowl and the antebowl together. A configuration and dimensional attributes of the antebowl is associated with reduced smoke production during operation, particularly for low to mid-load transients.

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.