A method and a system for controlling combustion of a natural gas engine. The method includes: determining, based on a current operation parameter of a natural gas engine, an operation state of the natural gas engine, and calculating a total injection quantity of natural gas and pilot diesel required by the natural gas engine in the operation state; adopting a direct injection diffusion-combustion mode in a case that the operation state is an idle state or a low load state; adopting a natural gas homogeneous hybrid active control compression-ignition mode in a case that the operation state is a medium load state; configuring the total injection quantity into three parts including a compression-ignition natural gas injection quantity, a pilot diesel injection quantity, and a diffusion-combustion natural gas injection quantity in a case that the operation state is a high load state, and sequentially injecting them into a combustion chamber.

A method for controlling an internal combustion engine is provided, which includes defining a first area in which the engine operates in a stoichiometric combustion mode and a second area in which the engine operates in a lean combustion mode, on an operation map defined by the engine load and speed, and causing a controller to determine that an operation point on the operation map shifts from the first area to the second area based on signals from an accelerator opening sensor and a crank angle sensor, predict a length of time that the operation point stays in the second area, switch a combustion mode to the lean combustion mode when the predicted time is longer than a given period of time, and maintain the stoichiometric combustion mode when the predicted time is shorter than the given period of time.

An apparatus for controlling an environment-friendly vehicle, a system having the same, and a method thereof are provided. The apparatus includes a processor to perform a control operation to expand an operable area based on a motor efficiency gain and a state of charge (SOC) of a battery in an Homogeneous Charge Compression Ignition (HCCI) operation or a lean burn operation, and a storage to store the motor efficiency gain and the SOC of the battery, which are acquired by the processor.

Methods and systems for operating an engine with split lambda modes are provided. At least one example method comprises, calculating a stoichiometric torque output of the plurality of cylinders; then applying one or more lean torque modifiers for every lean cylinder of the one or more non-stoichiometric cylinders to the stoichiometric torque output to calculate a lean torque output. In at least one example, one or more rich torque modifiers for every rich cylinder of the one or more non-stoichiometric cylinders may be applied to the stoichiometric torque output to calculate a rich torque output. Further, the lean torque output and the rich torque output may be summed to calculate a total engine torque output.

A control system for a compression-ignition engine is provided, which includes an engine configured to combust a mixture gas inside a combustion chamber by compression ignition, a fuel injector attached to the engine, a state function adjusting part attached to the engine and configured to adjust at least introduction of fresh air into the combustion chamber, a three-way catalyst provided in an exhaust passage of the engine, a wall temperature acquiring part configured to acquire a parameter related to a temperature of a wall of the combustion chamber, and a controller. A swirl flow is generated inside the combustion chamber to circle along the wall. When the wall temperature of the combustion chamber is below a given wall temperature, the controller sets an air-fuel ratio of the mixture gas substantially to a stoichiometric air-fuel ratio so as to remain within a purification window of the three-way catalyst.

A control system for a pre-mixture compression-ignition engine is provided, configured such that in a first combustion mode, the control unit controls the fuel injection valve to have a fuel amount within a mixture gas in an outer circumferential portion of the combustion chamber larger than in the center portion, the swirl generating part to generate a swirl flow in the outer circumferential portion, and the spark plug to ignite the mixture gas in the center portion. In a second combustion mode, the control unit controls the fuel injection valve to start a fuel injection on intake stroke so that the mixture gas is formed in the entire combustion chamber, the swirl generating part so that a swirl flow becomes weaker than in the first combustion mode, and the spark plug to ignite the mixture gas before CTDC.

An internal combustion engine is provided with a cylinder injector injecting fuel directly into a combustion chamber; an intake injector injecting fuel into an intake passage; and a control device controlling injection of fuel from these injectors. The control device is configured to perform a first control, in which an air-fuel mixture in the combustion chamber is formed by only fuel injected from the cylinder injector, until a predetermined timing after startup of the internal combustion engine, and to perform a second control, in which an air-fuel mixture in the combustion chamber is formed by fuel containing a larger amount of fuel injected from the intake injector than fuel injected from the cylinder injector, and after the predetermined timing. The air-fuel ratio of the mixture during the second control is smaller than the air-fuel ratio of the air-fuel mixture during the first control and smaller than the stoichiometric air-fuel ratio.

A control method for internal combustion engine with a fuel injection valve configured to directly inject fuel into a cylinder and an ignition plug configured to directly spark-ignite the fuel injected from the fuel injection valve includes comparing an actual behavior, which is an actual changing behavior of an engine revolution speed at an engine start, to a reference behavior set in advance, and switching from stratified combustion in which a fuel spray injected from the fuel injection valve and staying around the ignition plug is directly spark-ignited to homogeneous combustion in which a homogeneous air-fuel mixture is formed in a combustion chamber and the fuel is burned and increasing a mechanical compression ratio of the internal combustion engine as compared to the case where the actual behavior and the reference behavior match if the actual behavior is different from the reference behavior.

When an incremental amount of a steering angle exceeds a reference incremental amount, an ECU 60 executes vehicle attitude control of reducing an output torque of an engine, and, in a given operating range, drives a spark plug 16 in a manner allowing an air-fuel mixture to be self-ignited at a given timing, thereby executing SPCCI combustion. When there is a request for an additional deceleration from the vehicle attitude control (#12: YES), and the SPCCI combustion is performed (#13: YES), the ECU 60 executes fuel amount reduction control of reducing the amount of fuel to be supplied into a cylinder 2 (#14), so as to attain torque reduction for the vehicle attitude control. On the other hand, when the SPCCI combustion is not performed (#13: NO), the ECU 60 executes ignition retardation control of retarding an ignition timing of the spark plug 16 (#15).

A vehicular internal combustion engine system includes an internal combustion engine and an electric intake air supply device. The internal combustion engine is shifted into a stoichiometric combustion mode, and a lean combustion mode. The electric intake air supply device is driven by an on-vehicle battery, and employed to contribute a part of intake air quantity at least under a specific operating condition when in the lean combustion mode. A control method includes: determining a requested electric energy of the electric intake air supply device for a shift into the lean combustion mode in response to a shift from a stoichiometric combustion operation region into a lean combustion operation region; and continuing the stoichiometric combustion mode, without operation of the electric intake air supply device, when the on-vehicle battery is in an insufficient state of charge with respect to the requested electric energy.