A diesel engine comprises: a cylinder head covering one end of a cylinder; a piston having a crown surface opposed to the cylinder head and reciprocatingly movable in the cylinder; and a fuel injection valve attached to the cylinder head, wherein the crown surface of the piston is formed with a cavity which is concaved toward a side opposite to the cylinder head, and has a round shape in top plan view, and the fuel injection valve is formed with a nozzle hole directed toward the inside of the cavity, and wherein a wall surface defining the cavity has a wall segment formed in a periphery of the cavity at a position deviated from a directional direction of the nozzle hole and protruding toward a radially inward side of the piston in approximately parallel to a plane including a central axis of the piston.

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, the first side surface having a generally concave shape, the second side surface having a generally flat or convex shape.

An engine includes a combustion chamber including a cylinder wall defining a cylinder, a fuel injector disposed in a first opening in the cylinder wall and a piston head disposed in the cylinder. A piston bowl at least partially defined by a wall having a generally spiral shape is provided in a top of the piston head.

A piston for a diesel engine includes a piston body having a skirt and crown. The piston body has portions defining an outer combustion bowl and an inner combustion bowl within the piston body through the crown. The outer combustion bowl has a curved annular side wall extending from the crown surface and an annular flat shelf extending from the curved annular side wall. The new stepped bowl design integrates a bottom profile with smoothly varying curvature and a sharp step at the top. The annular flat shelf is recessed a distance in the range of 2.5-4.5 millimeters from a line coplanar with the crown surface. The piston body defines an outer convex curved surface connecting the curved annular side wall to the crown surface. The outer convex curved surface has a radius of curvature in the range of 0.25-0.75 millimeter.

A method for producing a piston for an internal combustion engine may include the steps of: producing a piston upper part from a first blank via a deformation process; producing a piston lower part from a second blank via at least one of a deformation process and a casting process; connecting the first blank of the piston upper part and the second blank of the piston lower part to form a piston body via a welding process; and performing at least one of a secondary machining process and a finish machining process of the piston body to produce the 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.

This invention discloses a combustion method, which is for an internal combustion engine, which utilizes variable spray patterns matched with a combustion chamber composing of multiple connected spaces based on injection timings and engine loads. This invention provides means to control propagation paths of combustion reaction radicals and control pressure rise rate, and also provides means to promote stratification of premixed charges. An internal combustion engine utilizing the disclosed combustion methods is also disclosed.

A piston may include an outer peripheral surface and a crown. The outer peripheral surface may include first and second openings spaced about and extending through the outer peripheral surface. The crown may include a recess at least partially defined by a first lobe in fluid communication with the first opening and a second lobe in fluid communication with the second opening. Each of the first and second lobes may be recessed relative to an adjacent portion of the recess of the crown.

An internal combustion engine includes a combustion chamber having a piston, the piston having at least one arcuate indent of a first type formed in the top surface, and at least one arcuate indent of a second type, wherein the first type includes a first recirculation surface having a concave shape at a first radius and extending along a spiral direction adjacent the entry surface, and wherein the second type includes a second recirculation surface having a concave shape at a second radius that is smaller than the first radius. During operation, a fuel jet provided into the first type occupies a radially outward portion of the combustion chamber, and a fuel jet provided into the second type occupies a central portion of the combustion chamber.

An engine includes a combustion chamber including a cylinder wall defining a cylinder, a fuel injector disposed in a first opening in the cylinder wall and a piston head disposed in the cylinder. A piston bowl at least partially defined by a wall having a generally spiral shape is provided in a top of the piston head.