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.

An internal combustion engine includes an ignition plug and an electronic control unit. The electronic control unit is configured to: (i) execute a lean-burn operation in a first operation region, (ii) execute an operation in a second operation region at an air-fuel ratio lower than an air-fuel ratio during the lean-burn operation, and (iii) control a gas flow in a cylinder so that a ratio of a change in a gas flow speed around the ignition plug during ignition to a change in an engine rotation speed in a first engine rotation speed region within the first operation region is smaller than the ratio in a second engine rotation speed region within the second operation region.

The internal combustion engine comprises a swirl control valve able to change a strength of a swirl generated in a combustion chamber; a load sensor for detecting an engine load; and a control device for controlling the swirl control valve. The control device controls the swirl control valve, when the engine load detected by the load sensor is lower than a predetermined load, so that the swirl ratio is higher when a suction intake gas amount is increasing, compared to when it is decreasing.

A four-stroke reciprocating piston internal combustion engine is disclosed. The engine includes an even number of cylinders grouped into a first half and a second half. An exhaust gas turbocharger has a first turbine inlet and a second turbine inlet. Each of the cylinders has an intake duct with an intake opening, a first exhaust duct with a first exhaust opening, and a second exhaust duct with a second exhaust opening. The first half of cylinders is connected via the respective first exhaust ducts to the first turbine inlet and is connected via the second exhaust ducts to the second turbine inlet. The second half of cylinders is connected via the respective first exhaust ducts to the second turbine inlet and is connected via the respective second exhaust ducts to the first turbine inlet. The respective second exhaust openings have a larger diameter than the respective first exhaust openings.

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 includes a first intake valve, a second intake valve, an accelerator open degree sensor that detects a load state, and an ECU 26 that controls the valve opening timing of the first and second intake valves and an amount of intake gas introduced to a combustion chamber from the first and second intake valves. When a load of a vehicle increases, the ECU reduces the ratio of the amount of intake gas from, among the two or more intake valves, the second intake valve having a later valve opening timing, whereas when the load decreases, the ECU increases the ratio.

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.

The present disclosure provides an engine structure for a vehicle. The engine structure includes: an intake port, a port plate provided in the single flow path of the intake port, and an injector. The port plate is longitudinally parallel to the flow path of the intake port so as to divide the flow path of the intake port into upper and lower flow paths, and the port plate includes an extension portion formed on part of a downstream end of the port plate such that the extension portion of the downstream end of the port plate extends longer than other portion of the downstream end of the port plate. In particular, the injector is provided in the intake port, and sprays fuel beyond the extension portion so as to inhibit the fuel from adhering to the port plate.

Methods and systems are provided for a charge motion control valve mounted within a flow passage in an intake manifold coupled to an engine. In one example design, a control valve comprises a valve plate with a pivot axis mounted in a body coupled to a manifold runner, the plate having a rear portion overhanging the pivot; and a first sealing surface in the manifold runner to receive a surface of the rear portion of the valve plate when fully opened; and a second sealing surface in the body to receive an opposite surface of the rear portion of the valve plate when fully closed. In this way, the valve plate may be adjusted to block a portion of a flow passage within the body to minimize air leakages at a periphery of the passage while redirecting air flow to create swirl motion downstream of the valve plate.

Methods and systems are provided for a charge motion control valve mounted within a flow passage in an intake manifold coupled to an engine. In one example design, a control valve comprises a valve plate with a pivot axis mounted in a body coupled to a manifold runner, the plate having a rear portion overhanging the pivot; and a first sealing surface in the manifold runner to receive a surface of the rear portion of the valve plate when fully opened; and a second sealing surface in the body to receive an opposite surface of the rear portion of the valve plate when fully closed. In this way, the valve plate may be adjusted to block a portion of a flow passage within the body to minimize air leakages at a periphery of the passage while redirecting air flow to create swirl motion downstream of the valve plate.