A control apparatus for a compression-ignition type engine is applied to an engine capable of carrying out partial compression ignition combustion. When the partial compression ignition combustion is carried out, an ignition control section of the control apparatus causes an ignition plug to carry out: main ignition in which a spark is generated to initiate the SI combustion; and preceding ignition in which the spark is generated at an earlier time point than the main ignition. An injection control section causes the ignition plug to inject fuel in an intake stroke. The ignition control section sets energy of the preceding ignition to be lower than energy of the main ignition and causes the ignition plug to carry out the preceding ignition after the fuel injection in the intake stroke or an early period or a middle period of a compression stroke.

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.

A compression ignition engine may operate using autoignition resistant fuels by laser-assisted ignition where a focused laser beam directly heats a spray of fuel proximate to an injector nozzle to promote a lifted flame combustion avoiding knock that could occur with the ignition of premixed fuel.

Methods and systems are provided for a pre-chamber. In one example, a pre-chamber comprises a plurality of slots fluidly coupling it to a primary combustion chamber. The plurality of slots comprising a plurality of corresponding flaps configured to direct gases through the plurality of slots.

An engine 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 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 lower when a swirl flow is gentle than when the swirl flow is intense.

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. A 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 performs the fuel injection in an intake stroke, and retards a start timing of the injection when an engine load is high compared to that when the load is low.

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. A 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 performs the fuel injection in an intake stroke, and retards a start timing of the injection when an engine load is high compared to that when the load is low.

In a combustion cycle in which fuel for forming a homogenized air-fuel mixture in the combustion chamber is injected from the first fuel injector, ignition-use fuel for forming an ignition-use air-fuel mixture in the vicinity of the electrode part is injected from the second fuel injector, and lean combustion is performed by an excess air rate of 2.0 or more, the ignition-use fuel is injected by at least an injection rate of 1.0 mm.sup.3/ms or more for a duration of 250 μs or more in an interval from a crank angle advanced by exactly 20 degrees from an ignition timing of the spark plug to the ignition timing, and the quantity of the ignition-use fuel is 2.0 mm.sup.3/st or less.

In a combustion cycle in which fuel for forming a homogenized air-fuel mixture in the combustion chamber is injected from the first fuel injector, ignition-use fuel for forming an ignition-use air-fuel mixture in the vicinity of the electrode part is injected from the second fuel injector, and lean combustion is performed by an excess air rate of 2.0 or more, the ignition-use fuel is injected by at least an injection rate of 1.0 mm.sup.3/ms or more for a duration of 250 μs or more in an interval from a crank angle advanced by exactly 20 degrees from an ignition timing of the spark plug to the ignition timing, and the quantity of the ignition-use fuel is 2.0 mm.sup.3/st or less.

A combustion chamber structure in which an installation hole of the injector is improved to realize a rapid combustion and to reduce an unburned hydrocarbon. In the combustion chamber, a leading end of an injector is withdrawn from an upper end of an opening of an installation hole, and an additionally expanded surface area is formed on an upper inner surface of the installation hole from a portion to which the leading end of the injector is situated to an opening end of the installation hole. An angle between the additionally expanded surface area and a joint surface of a cylinder head is narrower than an angle between a center axis of the installation hole and the joint surface.