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.

A direct-injection stratified charge internal combustion engine includes a combustion cylinder to receive an air-fuel mixture, and an air intake port to inlet air into the combustion cylinder. The direct-injection engine also includes a fuel injector configured to deliver fuel within the cylinder in a spray pattern substantially aligned to a cylinder central axis to create the air-fuel mixture. A spark igniter is located within a path of the spray pattern to ignite combustion of the air-fuel mixture. The dire-injection engine further includes a movable piston defining a lower boundary of the combustion cylinder to contain the combustion of the air-fuel mixture. The piston is configured to include a bowl portion having local geometric features located on an intake port side of the combustion cylinder to redirect fluid flow towards a vortex in fluid communication with a combustion location near the cylinder central axis.

An internal combustion engine comprising the fuel injector arranged in the combustion chamber. The primary fuel injection and the secondary fuel injection from the fuel injector are successively performed to cause autoignition of an injected fuel of the primary fuel injection and autoignition of an injected fuel of the secondary fuel injection. A temperature region suppressing change of an ignition delay time where a change of ignition delay time with respect to a rise in temperature in the combustion chamber is suppressed appears in the compression stroke at a temperature in the combustion chamber of 700K to 900K. The secondary fuel injection is performed if the temperature in the combustion chamber is a temperature within the temperature region suppressing change of the ignition delay time during the compression stroke. The primary fuel injection is performed during the compression stroke or suction stroke before the temperature in the combustion chamber reaches a temperature in the temperature region suppressing change of the ignition delay time at a fuel injection timing at which the injected fuel of the secondary fuel injection is autoignited after the injected fuel of the primary fuel injection is autoignited.

A water supply control apparatus is applied to an in-cylinder injection type internal combustion engine (1) which injects fuel from a central area (2a) in a cylinder (2). The water supply control apparatus comprises a condensed water supply mechanism (22) where a state of supplying condensed water (CW) into the cylinder (2) is changeable between a first supply state that the condensed water (CW) is supplied to a whole inside of the cylinder (2) and a second supply state that the condensed water (CW) is limitedly supplied to the central area (2a) of the cylinder (2). In the second supply state, the supply amount of condensed water supplied into the cylinder (2) in the second supply state is less than the supply amount of condensed water supplied into the cylinder (2) in the first supply state.

Gaseous fuel injection pressures are normally less than liquid fuel injection pressures, resulting in reduced gaseous fuel jet momentum and mixing. A combustion system for an internal combustion engine comprises an intake port and valve, a cylinder and a piston that cooperate to provide a quiescent combustion chamber. The piston includes a re-entrant type piston bowl comprising an outer periphery and a protuberance emanating from the outer periphery. A fuel injector is configured to directly introduce a gaseous fuel into the combustion chamber and an ignition source is provided for igniting the gaseous fuel. A controller actuates the fuel injector such that a gaseous fuel jet is directed towards and splits upon impacting the protuberance forming first and second fuel plumes. The first fuel plume is redirected towards a first mixing zone adjacent a cylinder head and the second fuel plume redirected towards a second mixing zone adjacent the piston bowl.

A controller injects fuel into a cylinder at a high fuel pressure of 30 MPa or higher, at least in a period between a terminal stage of a compression stroke and an initial stage of an expansion stroke when an operating mode of an engine body is at least in a first specified sub-range of a low load range, and at least in a second specified sub-range of a high load range. The controller sets an EGR ratio in the first specified sub-range to be higher than an EGR ratio in the second specified sub-range, and advances start of fuel injection in the first specified sub-range to start of fuel injection in the second specified sub-range.

Disclosed herein is a fuel injection control device for a direct injection engine including an engine body (engine 1) and a fuel injection control unit (engine controller 100). The fuel injection control unit injects a fuel in a predetermined injection mode into a combustion chamber (17) such that while the engine body is warm, an air-fuel mixture layer and a heat-insulating gas layer, surrounding the air-fuel mixture layer, are formed in the combustion chamber at a point in time when an air-fuel mixture ignites, and changes the injection mode of the fuel into the combustion chamber such that while the engine body is cold, the lower the temperature of the engine body is, the thinner the heat-insulating gas layer becomes.

A combustion chamber is provided within an internal combustion engine, the chamber bounded by a cylinder bore, a primary end, and a secondary end. The secondary end reciprocates between a TDC position nearest the primary end and a BDC position. Induction and exhaust ports are timed to open and close to transfer air into, and gasses from, the chamber. The chamber becomes fuel stratified when the secondary end is positioned within a stratified distance of the primary end. When stratified, the chamber is comprised of a central region, a perimeter region, and a transfer passageway between regions. A fuel injector at the primary end injects fuel only into the central region and only prior to ignition. The perimeter region pumps air into the central region prior to ignition, creating tumble turbulence. Combustion is initiated near TDC in the central region and concluded near TDC in the transfer passageway.

An engine has an engine body, an injector, and a control section which controls a fuel injection amount and an injection state of the injector. The control section predicts a state of temperature in the combustion chamber, and controls the injector such that a volume of an air-fuel mixture layer formed in the combustion chamber is larger when the predicted temperature is high, than when the predicted temperature is low, even when same fuel amounts are injected.

When a predetermined restart condition is satisfied after an engine is automatically stopped, whether or not a piston of a stopped-in-compression-stroke cylinder which is in a compression stroke falls within a specific range set at a bottom dead center side of a predetermined upper limit position is determined. When the piston of the stopped-in-compression-stroke cylinder falls within the specific range, a first compression start is executed in which fuel is injected from an injector into the stopped-in-compression-stroke cylinder for the first time and is then self-ignited. In the first compression start, a start timing of a first fuel injection operation with respect to the stopped-in-compression-stroke cylinder is set to be earlier as a stop position of the piston of the cylinder gets closer to the bottom dead center within the specific range.