A compression-ignition engine control system is provided, which includes an intake phase-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 retard the intake valve open timing on an advancing side of TDC of an exhaust stroke, as the engine load increases within the first range, and advance the intake valve close timing on a retarding side of TDC of intake stroke, as the engine load increases within the second range.

A method of implementing control logic of a compression ignition engine is provided. The engine includes an injector, a variable valve operating mechanism, an ignition plug, at least one sensor, and a processor. The processor outputs the signal to the ignition plug in a specific operating state so that unburnt mixture gas combusts by self ignition after the ignition plug ignites the mixture gas inside a combustion chamber. The method includes determining a geometric compression ratio of the engine, and determining control logic defining a valve opening angle CA of an intake valve. The valve opening angle CA (deg) is determined so that the following expression is satisfied, if the geometric compression ratio is <14, 40+800+DCA60550+D,. Here, D is a correction term according to the engine speed NE (rpm), D=3.310.sup.10NE.sup.31.010.sup.6NE.sup.2+7.010.sup.4NE.

An internal combustion engine includes a fuel injection system including a fuel injector disposed to inject fuel into the combustion chamber, and a plasma ignition system including a groundless barrier discharge plasma igniter that protrudes into the combustion chamber. A controller includes an executable instruction set to control the engine in a compression-ignition mode when the output torque request indicates a low load condition, including instructions to control a variable valve actuation system and control the plasma ignition system to execute plasma discharge events subsequent to controlling the fuel injection system to execute a fuel injection event, wherein the fuel injection event achieves a cylinder charge having a lean air/fuel ratio.

Some embodiments described herein relate to a method of operating a compression ignition engine. The method of operating the compression ignition engine includes opening an intake valve to draw a volume of air into a combustion chamber, closing an intake valve, and moving a piston from a bottom-dead-center (BDC) position to a top-dead-center (TDC) position in the combustion chamber at a compression ratio of at least about 15:1. The method further includes injecting a volume of fuel into the combustion chamber at an engine crank angle between about 330 degrees and about 365 degrees during a first time period. The fuel has a cetane number less than about 40. The method further includes combusting substantially all of the volume of fuel. In some embodiments, a delay between injecting the volume of fuel into the combustion chamber and initiation of combustion is less than about 2 ms.

A method of operating an engine includes operating the engine in first and second engine operating map regions by performing passive jet ignition combustion with a first stoichiometric fuel mixture and a first volume of residual gas. The engine is operated in a third engine operating map region by performing turbulent jet controlled compression ignition (TJCCI) with an ultra lean fuel mixture and a first volume of cooled exhaust gas recirculation, a fourth engine operating map region by performing passive jet ignition combustion with a third stoichiometric fuel mixture and a second volume of cooled exhaust gas recirculation, and a fifth engine operating map region, characterized by shutting off the engine. The engine is operated in a mode transition region between the second, third, and fourth engine operating map regions by performing passive jet ignition combustion with a second stoichiometric fuel mixture and a second volume of residual gas.

Some embodiments described herein relate to a method of operating a compression ignition engine. The method of operating the compression ignition engine includes opening an intake valve to draw a volume of air into a combustion chamber, closing an intake valve, and moving a piston from a bottom-dead-center (BDC) position to a top-dead-center (TDC) position in the combustion chamber at a compression ratio of at least about 15:1. The method further includes injecting a volume of fuel into the combustion chamber at an engine crank angle between about 330 degrees and about 365 degrees during a first time period. The fuel has a cetane number less than about 40. The method further includes combusting substantially all of the volume of fuel. In some embodiments, a delay between injecting the volume of fuel into the combustion chamber and initiation of combustion is less than about 2 ms.

A compression ignition gasoline engine includes a fuel injection valve for injecting fuel containing gasoline as a main component into a cylinder; an EGR device operative to perform high-temperature EGR of introducing burnt gas generated in the cylinder into the cylinder at a high temperature; and a combustion control unit for controlling the fuel injection valve and the EGR device in such a way that HCCI combustion in which fuel injected from the fuel injection valve self-ignites within the cylinder occurs. The combustion control unit controls the EGR device, in at least a partial load operating range in which HCCI combustion is performed, in such a way that the EGR rate increases, as compared with a low load condition, in a high load condition in which G/F being a ratio between a total amount of gas and a fuel amount within the cylinder decreases.

Methods and systems are provided for reducing exhaust residuals during light load conditions in a split exhaust engine via a check valve. In one example, a scavenge exhaust manifold may be maintained above a threshold pressure by introducing fresh air into the scavenge manifold during a valve overlap period, the scavenge manifold coupled to a cylinder of an engine and coupled to an intake passage of the engine.

A method of operating an engine includes operating the engine in first and second engine operating map regions by performing passive jet ignition combustion with a first stoichiometric fuel mixture and a first volume of residual gas. The engine is operated in a third engine operating map region by performing turbulent jet controlled compression ignition (TJCCI) with an ultra lean fuel mixture and a first volume of cooled exhaust gas recirculation, a fourth engine operating map region by performing passive jet ignition combustion with a third stoichiometric fuel mixture and a second volume of cooled exhaust gas recirculation, and a fifth engine operating map region, characterized by shutting off the engine. The engine is operated in a mode transition region between the second, third, and fourth engine operating map regions by performing passive jet ignition combustion with a second stoichiometric fuel mixture and a second volume of residual gas.

A control device for an internal combustion engine including a fuel injection valve and an actuator includes an electronic control unit. The fuel injection valve directly injects fuel into a combustion chamber. The actuator is configured to change the oxygen concentration in intake gas supplied to the combustion chamber of the internal combustion engine. The electronic control unit is configured to control fuel injection from the fuel injection valve and the actuator.