A control system of a compression-ignition engine is provided, which includes an engine configured to cause combustion of mixture gas inside a combustion chamber, a spark plug, and a controller configured to operate the engine. The combustion is performed in a given mode in which, after the spark plug ignites the mixture gas to start combustion, unburned mixture gas combusts by self-ignition. The controller has a heat amount ratio changing module configured to change, according to an engine operating state, a heat amount ratio as an index relating to a ratio of a heat amount generated when the mixture gas combusts by flame propagation with respect to a total heat amount generated when the mixture gas inside the combustion chamber combusts. The controller causes the changing module to increase the heat amount ratio at a high engine speed than at a low engine speed.

A control system of a compression-ignition engine is provided, which includes an engine, an injector, a spark plug, 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. After the spark plug ignites mixture gas to start combustion, unburned mixture gas combusts by self-ignition. The controller outputs the control signal to the injector to perform a first-stage injection of fuel and then a second-stage injection in which fuel is injected to at least form the mixture gas around the spark plug. The controller also outputs the control signal to the injector to control a ratio of the injection amount of the second-stage injection with respect to the injection amount of the first-stage injection to be higher at a high engine speed than at a low engine speed.

Apparatuses, systems and method for utilizing multi-zoned combustion chambers (and/or multiple combustion chambers) for achieving compression ignition (and/or spark-assisted or fuel-assisted compression ignition) in an internal combustion engine are provided. In addition, improved apparatuses, systems and methods for achieving and/or controlling compression ignition (and/or spark-assisted or fuel-assisted compression ignition) in a Siamese cylinder internal combustion engine are provided.

A piston for an engine may include a piston body. The piston body may include a piston crown disposed symmetrically about a central longitudinal axis of the piston. A combustion bowl may be recessed into the piston body and may be offset axially inwardly with respect to the piston crown. A central bowl apex may protrude axially from the combustion bowl and may be offset axially inwardly with respect to the piston crown. A first bowl apex may protrude axially from the combustion bowl and may be disposed radially inwardly with respect to the piston crown. A second bowl apex may protrude axially from the combustion bowl and may be disposed radially inwardly with respect to the first bowl apex and may be radially between the first bowl apex and the central bowl apex. The second bowl apex may be offset axially inwardly with respect to the central bowl apex.

A combustion system for an internal combustion engine includes a cylinder having a cylinder wall defining a bore, a piston disposed inside the bore, a combustion chamber delimited by a cylinder head, the cylinder wall, and the piston. The piston includes a piston bowl defining a floor portion, and at least one scooped recess extending radially outwardly from a periphery of the piston bowl. The internal combustion engine further includes a fuel injector configured to inject fuel into the combustion chamber as a plurality of fuel jets at a main injection timing such that each fuel jet contacts the floor portion of the piston bowl and follows a profile of the piston bowl and enter the at least one scooped recess. Furthermore, at least one of the plurality of is deflected by the at least one scooped recess away from the cylinder wall.

Disclosed is a coating for reducing or preventing hot-gas oxidation of the piston in an internal combustion engine. Said coating comprises a polysilazane-based polymer.

An engine includes: a piston including a cavity; a cylinder head configured so as to form a combustion chamber having a pent roof shape; a fuel injection valve configured to inject fuel in a period from a second half of a compression stroke until a first half of an expansion stroke; and a spark plug arranged at a position corresponding to an upper side of the cavity. Injection openings which are arranged in a circumferential direction surrounding a longitudinal axis of the valve and through each of which the fuel is injected in a direction inclined relative to the longitudinal axis by a predetermined angle is formed such that when a height of a ceiling of the combustion chamber at a position corresponding to an edge end portion of the cavity in an injection direction of the injection opening is large, the injection angle of the injection opening is large.

A structure of a combustion chamber is provided. The structure includes a cavity formed in a central part of a crown surface of a piston and a wall surface constituting the cavity. The wall surface has a central ridge portion bulging farther toward a bottom surface of a cylinder head toward a center of the cavity, a periphery concave portion formed radially outward of the central ridge portion to concave radially outward, and a lip portion formed between the periphery concave portion and an opening edge of the cavity to convex radially inward. An outer circumferential part of the crown surface has a first portion and a second portion located radially outward of the first portion. A stepped portion is formed between the first and second portions. A stepped portion volume ratio of a stepped portion volume to a top dead center volume is set to 0.1 or smaller.

A combustion chamber structure for an internal combustion engine includes, in a piston top part, a concave portion formed eccentrically with respect to a cylinder center axis, and a tapered portion that connects an upper end face of the piston top part and a side face of the concave portion. The tapered portion is formed so that a tapered portion volume (volume of a space formed between the tapered portion and an upper wall surface of the combustion chamber) in a first portion of the piston top part is greater than a tapered portion volume in a second portion that is nearer than the first portion to an eccentric direction of the concave portion from the cylinder center axis.

The present invention relates to a combustion chamber structure of an engine configured to inject fuel in a predetermined operation range in a period from a second half of a compression stroke until a first half of an expansion stroke to perform ignition after a compression top dead center. The combustion chamber structure includes: a piston including a cavity; a fuel injection valve provided at a middle portion of the piston; and a spark plug provided at a radially outer side of the middle portion of the piston and an upper side of the cavity. The cavity is formed by a curved surface having curvature that becomes larger as the curved surface extends toward the radially outer side. A tangential direction of an edge end portion of the curved surface intersects with a combustion chamber ceiling radially outward of the spark plug.