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.

A compression-ignition engine control system is provided, which includes an intake variable mechanism and a controller. Within a first operating range and a second operating range on a higher engine load side, the controller controls the variable mechanism to form a gas-fuel ratio (G/F) lean environment in which an air-fuel ratio inside a cylinder is near a stoichiometric air-fuel ratio and burnt gas remains inside the cylinder, and controls a spark plug to spark-ignite mixture gas inside the cylinder to combust in a partial compression-ignition combustion. The controller controls the variable mechanism to advance the intake valve open timing on an advancing side of a TDC of the exhaust stroke, as the engine load increases within the first range, and retard the intake valve open timing on the advancing side of the TDC of the exhaust stroke, as the engine load increases within the second range.

A control system of a compression-ignition engine includes an intake variable mechanism and a controller. In a second operating range, the controller controls the intake variable mechanism so that, while partial compression-ignition combustion is performed under an air-fuel ratio (A/F) lean environment, an intake valve open timing takes timing at an advanced side of an exhaust TDC. In a first operating range on a lower load side, the controller controls the intake variable mechanism so that, while the partial compression-ignition combustion is performed under the A/F lean environment, under the same engine speed condition, the intake valve close timing is more retarded within a range on a retarded side of an intake BDC as the engine load decreases, and an absolute value of a change rate of the intake valve close timing to the engine load becomes larger than in the second range.

A control device of an engine including a cylinder, a piston, a cylinder head, and a combustion chamber, is provided. The device includes intake and exhaust ports, a swirl control valve, a fuel injection valve attached to the cylinder head to be oriented into the combustion chamber and having first and second nozzle ports, and a control unit. The control unit includes a processor configured to execute a swirl opening controlling module to control the swirl control valve to have a given opening at which a swirl ratio inside the combustion chamber becomes 2 or above, and a fuel injection timing controlling module to control the fuel injection valve to inject fuel at a given timing at which the swirl ratio becomes 2 or above and a swirl flow from a lower portion to a higher portion of the combustion chamber in a side view occurs.

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).

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 cylinder head of an engine is provided, which includes first and second intake ports that open to a common cylinder. The first intake port opens to the cylinder to generate a swirl flow. The second intake port has a tumble flow generating part configured to cause intake air to become a tumble flow in the same direction as the swirl flow. The tumble flow generating part includes a helical part having an inner wall surface curving on a centerline perpendicular to an opening surface of the second port and continuing from a first port side to the opening of the second intake port toward at an opposite side from the first port. The opening of the second intake port has an edge part having an opening angle with respect to the centerline of the second port, the opening angle being smaller at an upstream side of the swirl flow.

A control system for a compression-ignition engine is provided, which includes an engine having a combustion chamber, an injector configured to supply fuel into the combustion chamber, a spark plug, a swirl valve provided to an intake passage of the engine, and a controller. The controller includes a processor configured to execute a swirl adjusting module to adjust a swirl valve opening to generate a swirl flow inside the combustion chamber, a fuel injection amount controlling module to control fuel injection amounts of pre-injection and post-injection so as to increase a ratio of an injection amount of the post-injection to a total fuel injection amount into the combustion chamber in one cycle as an engine speed increases, and a combustion controlling module to control the spark plug to ignite at a given ignition timing after the swirl generation and fuel injection, so that partial compression-ignition combustion is performed.

A control system for a compression-ignition engine is provided, which includes an engine having a combustion chamber, an injector, a spark plug, a swirl valve provided to an intake passage of the engine, and a controller connected to the injector, the spark plug, and the swirl valve to control them. The controller includes a processor configured to execute a swirl adjusting module to control an opening of the swirl valve so as to make the opening of the swirl valve smaller as an engine speed decreases and output a control signal to the injector to inject the fuel after the control of the swirl valve, and a combustion controlling module to output an ignition instruction to the spark plug so as to ignite at a given ignition timing after the EGR ratio adjustment, so that partial compression-ignition combustion is performed.

A combustion chamber structure for a spark-ignition internal combustion engine includes a combustion chamber, an ignition plug, and a guide portion. The combustion chamber is configured to produce tumble flow that swirls in an axial direction of a cylinder. The ignition plug is disposed in a central portion of an upper wall of the combustion chamber. The guide portion protrudes from the upper wall of the combustion chamber, and is configured to guide airflow passing through the central portion of the combustion chamber in an intake-exhaust direction of the combustion chamber while dispersing the airflow around the guide portion.