A control apparatus for an internal combustion engine carries out lean combustion to cause flame propagation to a homogeneous air-fuel mixture while drifting primary flames on a tumble flow by injecting fuel for ignition from a second fuel injection valve to a vicinity of an electrode portion and igniting an air-fuel mixture for ignition at a primary ignition timing, and to ignite an air-fuel mixture for accelerating combustion at a secondary ignition timing by injecting fuel for accelerating combustion in a squish area from the second fuel injection valve at a timing before an injection timing of the fuel for ignition and drifting the air-fuel mixture for accelerating combustion in a combustion chamber on the tumble flow. The secondary ignition timing is set as a timing allowing secondary flames produced by igniting the air-fuel mixture for accelerating combustion to be drawn into the squish area by a reverse squish flow.

A control method of an internal combustion engine including a spark plug and a fuel injection valve includes starting electric discharge of the spark plug after a gas flow in a direction from a side of the fuel injection valve toward a side of the spark plug is generated at a position of an electric discharge gap of the spark plug due to spray of the fuel injected from the fuel injection valve.

A method for operating an internal combustion engine includes moving a piston downward from a top dead center position to a bottom dead center position expanding a combustion chamber in an intake stroke, dispensing a first portion of fuel into the combustion chamber, subsequent to moving the piston downward in the intake stroke, moving the piston upward in the vertical direction compressing the combustion chamber in a compression stroke, subsequent to moving the piston upward in the compression stroke, moving the piston downward in the vertical direction in an expansion stroke, while moving the piston downward in the vertical direction in the expansion stroke, dispensing a second portion of fuel into the combustion chamber, and while moving the piston downward in the expansion stroke, igniting at least a part of the first portion of fuel and the second portion of fuel.

A method of operating a hydrogen-fueled internal combustion engine. The engine is determined to have a mode control value, which represents a threshold torque. During operation of the engine, a demanded torque of the internal combustion engine is determined and compared to the threshold torque. If the demanded torque is less than the threshold torque, the engine is operated in a low load mode that uses spark ignition and pre-mixed combustion. If the demanded torque is greater than the threshold torque, the engine is operated in a high load mode that uses compression ignition and diffusion combustion.

A fuel injection control device for an engine is provided. A swirl generator generates a swirl flow inside a combustion chamber. A fuel injector with multiple nozzle holes injects fuel into the combustion chamber, and forms a lean mixture gas inside the combustion chamber. An spark plug ignites the lean mixture gas to cause a portion of the mixture gas to start combustion accompanied by flame propagation, and then combusts by self-ignition. The fuel injector has first and second nozzle holes, and a first atomized fuel spray injected from the first nozzle hole and a second atomized fuel spray injected from the second nozzle hole separate from each other by the swirl flow. The fuel injector sequentially performs a first injection and a second injection in an intake stroke. The controller makes an injection amount of the second injection greater than that of the first injection.

When an operation state switches from a first operation region A to a second operation region B, the valve timing of an intake valve and an exhaust valve is switched upon switching of the operation state from the first operation region A to the second operation region B. When the operation state switches from the first operation region A to the second operation region B, the air-fuel ratio is switched after a first predetermined time T1 has elapsed since when the actual valve timing of the intake valve became a second intake valve timing and the actual valve timing of the exhaust valve became a second exhaust valve timing. In this way, it becomes possible to ensure ignition when the operation state switches.

An engine system includes an engine, a main combustion chamber formed by a cylinder head and a piston, an auxiliary chamber formed with a communicating hole communicating with the main combustion chamber, an injector configured to inject fuel into the main combustion chamber, an ignition plug provided to the auxiliary chamber and configured to ignite a mixture gas inside the auxiliary chamber, an accelerator opening sensor, and a control device. The control device controls the injector so that an air-fuel ratio of the mixture gas inside the auxiliary chamber becomes a first air-fuel ratio when an engine load range is a first range, and the air-fuel ratio of the mixture gas inside the auxiliary chamber becomes a second air-fuel ratio leaner than the first air-fuel ratio when the engine load range is a second range where the engine load is higher than in the first range.

Emission of unburned hydrocarbons and soot is reduced while ensuring startability (ignitability) in a cold start mode of an internal combustion engine. Thus, fuel is injected with a first injection rate as an injection rate of a fuel injection valve 100 in a warm state in which a temperature of an engine 30 is equal to or higher than a set temperature, and the fuel is injected with a second injection rate lower than the first injection rate as the injection rate of the fuel injection valve 100 in a cold state in which the temperature of the engine 30 is lower than the set temperature at the same fuel pressure as that in the warm state.

A control unit controls a combustion state of an internal combustion engine in accordance with a drive torque requested by a driver. The control unit performs a switching control to switch at least a combustion state between lean-burn combustion and stoichiometric combustion. A monitor unit performs torque monitoring to determine abnormality of a request torque, which is requested to the internal combustion engine, and a generated torque of the internal combustion engine based on the request torque and an estimation torque, which is an estimation value of an actual torque of the internal combustion engine. A combustion state determining unit determines whether the combustion state in the control unit is the lean-burn combustion or the stoichiometric combustion. A computing unit computes the estimation torque in accordance with the combustion state determined by the combustion state determining unit.

When an operation state switches from a first operation region A to a second operation region B, the valve timing of an intake valve and an exhaust valve is switched upon switching of the operation state from the first operation region A to the second operation region B. When the operation state switches from the first operation region A to the second operation region B, the air-fuel ratio is switched after a first predetermined time T1 has elapsed since when the actual valve timing of the intake valve became a second intake valve timing and the actual valve timing of the exhaust valve became a second exhaust valve timing. In this way, it becomes possible to ensure ignition when the operation state switches.