A precombustion chamber gas engine includes a main-chamber forming portion forming a main combustion chamber, a precombustion-chamber forming portion forming a precombustion chamber communicating with the main combustion chamber via a plurality of nozzle holes, and an ignition device disposed in the precombustion chamber and having an ignition portion spaced from a main chamber central axis of the main combustion chamber at a predetermined distance. In a plan view, the precombustion chamber has a near-ignition region including the ignition portion and a far-ignition region opposite to the near-ignition region separated by a borderline passing through a precombustion chamber central axis of the precombustion chamber and perpendicular to a straight line passing through the precombustion chamber central axis and the ignition portion. The distance between the precombustion chamber central axis and a precombustion-chamber-side opening end, connected to the precombustion chamber, of a specific far nozzle hole which is at least one nozzle hole in the far-ignition region is shorter or longer than the distance between the precombustion chamber central axis and a precombustion-chamber-side opening end of a specific near nozzle hole which is at least one nozzle hole in the near-ignition region.

A spark plug for an internal combustion engine includes a housing, an insulator, a center electrode, a ground electrode, and an auxiliary chamber forming portion. The ground electrode faces the center electrode from an outer peripheral side and forms a discharge gap between the ground electrode and the center electrode. An auxiliary chamber is formed inside the auxiliary chamber forming portion. A distance in an axial direction between the discharge gap and a distal end of the auxiliary chamber is equal to or greater than a maximum wall thickness of the auxiliary chamber forming portion. The auxiliary chamber forming portion includes injection holes. The injection holes are formed in a state where openings on an outer side are located closer to a distal end than openings on the auxiliary chamber side. At least one of the injection holes is an injection hole in the axial direction formed along an axial direction of a plug. When viewed in the axial direction of the spark plug, a center of the axial injection hole is eccentric from a central axis of the spark plug toward the discharge gap.

Disclosed is a multiple combustion mode engine with ammonia fuel including an cylinder head, a cylinder sleeve, a piston, a main combustion chamber, an inlet valve and an exhaust valve, and further including a jet ignition device arranged on the cylinder head and used for providing an ignition source for the main combustion chamber, and an ammonia injector used for providing ammonia/air mixture gas for the main combustion chamber. Also disclosed is a control method of the multiple combustion mode engine with ammonia fuel. The time sequence of ammonia injection of the main combustion chamber and jet flame generation of the pre-chamber is controlled, the mixed state of the fuel/air in the main combustion chamber before ignition can be controlled, and finally different combustion modes, i.e. a premixed combustion mode and a diffusion combustion mode, are formed in the main combustion chamber.

The invention relates to an engine having prechamber ignition, in particular a gas engine, that comprises a main combustion space in a cylinder of the engine for combusting an air-fuel mixture and a prechamber having an ignition device arranged therein and a fuel injector arranged therein, wherein the prechamber has at least one transfer port that fluidically connects the prechamber to the main combustion space. The engine is characterized in that the fuel injector arranged in the prechamber is the only fuel injector via which fuel can be introduced into the associated main combustion space.

The invention relates to an engine having prechamber ignition, in particular a gas engine, that comprises a main combustion space in a cylinder of the engine for combusting an air-fuel mixture and a prechamber having an ignition device arranged therein and a fuel injector arranged therein, wherein the prechamber has at least one transfer port that fluidically connects the prechamber to the main combustion space. The engine is characterized in that the fuel injector arranged in the prechamber is the only fuel injector via which fuel can be introduced into the associated main combustion space.

In a spark plug, at least one injection hole serves as a ground-directed injection hole arranged to face a facing side of a ground electrode. An extension line of the center axis of the at least one ground-directed injection hole intersects with the facing side of the ground electrode at an intersection point. The facing side of the ground electrode has a closer region closer to the projection-end edge of the ground electrode than the intersection point is. The closer region of the facing side intersects with the extension line of the center axis of the ground-directed injection hole at a predetermined angle as viewed in the axial direction of the spark plug. The predetermined angle being an obtuse angle.

Methods and systems are provided for a cylinder head. In one example, a system comprises cylinder head having a bore arranged therein. The bore comprises a coupling element therein configured to selectively receive an ignition plug.

Methods and systems are provided for a cylinder head. In one example, a system comprises cylinder head having a bore arranged therein. The bore comprises a coupling element therein configured to selectively receive an ignition plug.

This spark plug includes a cap portion covering a center electrode and an end of a ground electrode from a front side. In a cross section including an axial line, where a pitch of an external thread of a metal shell is X (mm), an axial-line-direction distance between a crest of a rear-end ridge of a full thread portion of an external thread and a rear end of a contact portion of an insulator with which the metal shell contacts directly or via another member is A (mm), an axial-line-direction distance between the rear end of the contact portion and a front end of the insulator is B (mm), and an axial-line-direction distance between the rear end of the contact portion and a seating surface of the metal shell is C (mm), 0<A<4X, B≤15, and C≤3.6 are satisfied.

An engine system is provided, which includes a main combustion chamber, a subchamber, an injector that injects fuel into the main combustion chamber, a main spark plug that ignites a mixture gas inside the main combustion chamber, and a subspark plug that ignites the mixture gas inside the subchamber, an throttle valve, and a control device. In a first range, compression self-ignition combustion of the mixture gas inside the main combustion chamber is performed. In a second range, flame propagation combustion is performed while setting an air-fuel ratio of the mixture gas lower than that in the first range. Immediately after the transition from the first range to the second range, only the subignition is performed, or the subignition and the main ignition are performed while setting a timing of the main ignition to a timing same as or retarded from the subignition.