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.

An engine control apparatus includes an ignition control section and an injection control section. When partial compression ignition combustion is carried out, the ignition control section causes an ignition plug to carry out: main ignition in which a spark is generated in a late period of a compression stroke or an initial period of an expansion stroke to initiate the SI combustion; and preceding ignition in which the spark is generated at earlier timing than the main ignition. Also, when the partial compression ignition combustion is carried out, the injection control section causes the injector to inject fuel at such timing that the fuel exists in a cylinder at an earlier time point than the preceding ignition. Energy of the preceding ignition is set to be higher when an engine speed is high than when the engine speed is low.

Provided is an ignition control section and an injection control section. When partial compression ignition combustion is carried out, the ignition control section causes an ignition plug to carry out: main ignition in which a spark is generated in a late period of a compression stroke or an initial period of an expansion stroke to initiate SI combustion; and preceding ignition in which the spark is generated at earlier timing than the main ignition. Also, when the partial compression ignition combustion is carried out, the injection control section causes an injector to inject fuel at such timing that the fuel exists in a cylinder at an earlier time point than the preceding ignition. Ignition timing of the preceding ignition is set to be more retarded when an in-cylinder pressure specified by an in-cylinder pressure specification section is high than when the in-cylinder pressure is low.

An engine control apparatus includes an ignition control section and an injection control section. When the partial compression ignition combustion is carried out, the ignition control section causes an ignition plug to carry out: main ignition in which a spark is generated in a late period of a compression stroke or an initial period of a expansion stroke to initiate the SI combustion; and preceding ignition in which the spark is generated at earlier timing than the main ignition. Also, when the partial compression ignition combustion is carried out, the injection control section causes the injector to inject fuel at such timing that the fuel exists in a cylinder at an earlier time point than the preceding ignition. The energy of the preceding ignition is set to be higher when the in-cylinder pressure specified by the in-cylinder pressure specification section is high than when the in-cylinder pressure is low.

In a method, dynamic pressure oscillations in the intake tract or outlet tract of a respective internal combustion engine are measured during normal operation, and from these measured oscillations, a corresponding pressure oscillation signal is generated. A crankshaft phase angle signal is determined at the same time. From the pressure oscillation signal, an actual value of at least one characteristic of at least one selected signal frequency of the measured pressure oscillations in relation to the crankshaft phase angle signal is determined, and the current trimming of the intake tract is determined on the basis of the determined actual value, taking into consideration reference values of the corresponding characteristic of the respectively identical signal frequency for different trimmings of the intake tract.

Methods and systems are provided for a prechamber. In one example, a system includes a plurality of openings angularly arranged in a prechamber wall. The plurality of openings is oriented to receive and expel fluids in clockwise or counterclockwise directions.

An engine intake system includes: a port partition disposed to divide an intake port of a cylinder head into an upper portion and a lower portion; a first intake manifold configured to supply air, which flows from an air cleaner through a charger and an intercooler, to one of the upper portion and the lower portion of the port partition; a second intake manifold configured to supply the air, which flows from the air cleaner while bypassing the charger and the intercooler, to the other of the upper portion and the lower portion of the port partition; and a bypass valve disposed and configured to pass and block the air flowing into the second intake manifold from the air cleaner.

An engine controller calculates a pulsation correction value based on actuation states of an air bypass valve (ABV) and a wastegate valve (WGV) that change the shape of intake and exhaust flow passages of an exhaust turbocharger. The pulsation correction value is used to compensate for an output error of an airflow meter caused by intake pulsation. The engine controller also calculates a fuel injection amount of an injector, based on an output of the airflow meter that has been corrected based on the pulsation correction value.

The invention is provided with an ignition control section and an injection control section. When partial compression ignition combustion is carried out, the ignition control section causes an ignition plug to carry out: main ignition in which a spark is generated in a late period of a compression stroke or an initial period of an expansion stroke to initiate SI combustion; and preceding ignition in which the spark is generated at earlier timing than the main ignition. Also, when the partial compression ignition combustion is carried out, the injection control section causes an injector to inject fuel at such timing that the fuel exists in a cylinder at an earlier time point than the preceding ignition. Timing of the preceding ignition is more advanced when a swirl flow is gentle than when the swirl flow is strong.

An engine control apparatus includes an ignition control section and an injection control section. When the partial compression ignition combustion is carried out, the ignition control section causes an ignition plug to carry out: main ignition in which a spark is generated in a late period of a compression stroke or an initial period of a expansion stroke to initiate the SI combustion; and preceding ignition in which the spark is generated at earlier timing than the main ignition. Also, when the partial compression ignition combustion is carried out, the injection control section causes the injector to inject fuel at such timing that the fuel exists in a cylinder at an earlier time point than the preceding ignition. The energy of the preceding ignition is set to be higher when the in-cylinder pressure specified by the in-cylinder pressure specification section is high than when the in-cylinder pressure is low.