The invention relates to a combustion gas injector assembly (1) comprising a combustion gas injector (3) having groups (11a,b,c) of combustion gas nozzle openings distributed around the periphery, each group having at least one combustion gas nozzle opening (13), a combustion gas nozzle valve member (9a,b,c) of the combustion gas injector (3), which member can be controlled in the open position and closed position, is associated with each group (11a,b,c) of combustion gas nozzle openings, in order to selectively discharge the combustion gas via the at least one combustion gas nozzle opening (13). The combustion gas injector assembly (1) is configured to control the combustion gas nozzle valve members (9a,b,c) successively with a predetermined time offset (T) into the closed position.

When it is determined that the igniting environment is out of the desired range, the variable valve mechanism is controlled so that the swirl ratio is increased. When the swirl ratio becomes high, the discharge spark and the initial flame move largely in the flow direction of the swirl flow SW and approach the closest fuel spray. Therefore, the discharge spark and the initial flame are attracted to the closest fuel spray and the initial flame enlarges by involving the closest fuel spray (middle stage of FIG. 7). Further, the initial flame enlarges further by involving surrounded fuel spray (lower stage of FIG. 7).

An internal combustion engine includes an intake port configured to generate a swirl in a cylinder, an exhaust port, and a piston. The piston includes a top surface provided in an upper portion of the piston, a cavity provided from the top surface toward a lower portion of the piston around a central axis of the piston, and a connection surface connecting an inner edge of the top surface and an upper end of a side surface of the cavity to each other. The connection surface is provided to be closer to a lower portion side of the piston than the top surface. An area of the connection surface projected on a plane parallel to the top surface is larger on an intake port side than on an exhaust port side.

An internal combustion engine comprises a fuel injector 31, a spark plug 16, a piston 14 having a cavity 91, a swirl control device 95, and a control system 70. The cavity is formed so as to change in distance from the fuel injector to a side wall surface of the cavity, in the circumferential direction. The system performs ignition assist control for successively performing injections of main fuel and ignition assist fuel, makes an air-fuel mixture formed by the ignition assist fuel burn by flame propagation by the spark plug, and makes the remaining fuel burn by pre-mix compression self-ignition. The system controls the swirl control device during the ignition assist control so that when the engine load is high, the fuel sprayed heads toward parts of the side wall surface which are short in distances from the fuel injector.

Particular embodiments may provide a piston for a prechamber-type gas engine and a prechamber-type gas engine taking into consideration the shape of the piston top surface portion so that the region where flame propagation due to torch jet is delayed, a piston for a prechamber-type gas engine where torch jet formed by combustion a prechamber fuel in a precombustion chamber is injected to a main combustion chamber through a plurality of injection holes, may include a piston top surface portion comprising a land portion formed in a first region extending between axis line directions of adjacent injection holes, and the first region is positioned at a higher position than a second region extending across the axis line direction. The land portion may be formed on a cavity formed in the piston top surface portion. A plurality of land portions are provided corresponding to the plurality of injection holes, and the plurality of land portions are provided so as to be offset toward a same direction from a middle position between axis line directions of adjacent injection holes.

An engine system provided. The engine system includes a rotatable flow guide including a flow altering surface positioned upstream of an intake valve having a first side with a curved contour, the flow altering surface generating tumble and swirl flow patterns of intake airflow entering a cylinder through the intake valve in a plurality of active positions. The engine system further includes a flow guide actuator rotating the flow altering surface to alter the tumble and swirl flow patterns of the intake airflow.

A two-stroke internal combustion engine includes at least one gaseous communication charge passage between a crankcase chamber and a combustion chamber of the engine and a piston to open and close the top end of the transfer passage. The air inlet port to the transfer passage for stratified scavenging is opened and closed by the piston that has passages and cutouts. The charge inlet to the crankcase chamber is opened and closed by the piston. The air inlet passage is substantially asymmetrical to the layout of the transfer passages and are closer to one transfer passage compared to the other. The internal air passage in the piston is substantially parallel to the piston pin and the single air inlet passage is laterally off-set from the air-fuel inlet passage. The transfer passages are cover by plates to make them closed passages having opening at the transfer port in the cylinder and opening in the crankcase chamber for periodical gaseous communication between the crankcase chamber and the combustion chamber. The cover plate is a single piece covering the transfer passage channel along the cylinder and the crankcase. The air channel in the piston is below the piston crown and at least portion is above the piston pin. A spiraling transfer passage in the cylinder cavity is longer than the length of the transfer passage in a conventional stratified two-stroke engine.

An engine includes: a turbocharger including a turbine and a compressor; an EGR passage connecting an exhaust passage on an upstream side of the turbine and an air intake passage on a downstream side of the compressor; an EGR valve provided in the EGR passage; a bypass passage that bypasses the turbine; and a waste gate valve provided in the bypass passage. In the engine, when a boost pressure is increased to a limit pressure, a first boost pressure control is executed, in which the EGR valve is opened and the waste gate valve is closed. After the first boost pressure control starts, when an engine speed is increased to a prescribed value, a second boost pressure control is executed, in which the waste gate valve is opened in addition to the EGR valve.

A uniflow scavenging two-cycle engine includes an scavenging port having a swirling guide portion that guides scavenging gas into a cylinder in a direction inclined with respect to a radial direction of the cylinder, and a center guide portion that is provided to be closer to a crank side of the cylinder than the swirling guide portion and guides the scavenging gas further toward the center side of the cylinder than the swirling guide portion. At least a part of the center guide portion faces a piston when the piston is positioned at bottom dead center during the high compression ratio mode, and the center guide portion and the piston do not face each other or an area of facing the piston is smaller than that during the high compression ratio mode when the piston is positioned at bottom dead center during the low compression ratio mode.

A spark-ignition internal combustion engine includes a pent roof type combustion chamber, intake valves, exhaust valves, ignition plug, and an airflow guide member. The airflow guide member is provided on a housing of the ignition plug or a wall surface of at least one of pair of roofs. The airflow guide member is configured to deflect airflow that passes through the discharge gap at the time of ignition, in a direction that is inclined relative to a reference direction perpendicular to a line of intersection of wall surfaces of the pair of roofs as viewed in a direction of a center axis of a cylinder. A connecting portion of the ignition plug is located outside a direction of the airflow deflected by the airflow guide member.