In certain embodiments with large size prechambers and/or with prechambers that have large spark-gap electrode assemblies, a poor scavenge of the crevice volume may cause deterioration of the preignition margin, which then may limit the power rating of the engine, may cause the flow velocity field of the fuel-air mixture to be excessively uneven and may result in the deterioration of the misfire limit. One or more auxiliary scavenging ports may allow admission of fuel rich mixture to the crevice volume, thereby cooling the residual gases and preventing occurrence of preignition. More organized and powerful flow velocity fields may be obtained in the spark-gap electrode assembly region. This condition may result in a significant extension of the flammability limit and may significantly improve the combustion efficiency of the prechamber. Passive prechambers using the active scavenge concept may increase the engine power output and reduce the emission of pollutants from engine combustion.

Generally, embodiments of a pre-chamber unit having a pre-combustion chamber including one or more induction ports in a configuration which achieves flow fields and flow field forces inside the pre-combustion chamber which act to direct flame growth away quenching surface of the pre-combustion chamber.

A cylinder head for an internal combustion engine comprising a prechamber (3), wherein a prechamber gas valve (5) is fitted into a cavity in the cylinder head (2) and the prechamber gas valve (5) is connected to the prechamber (3) by way of a flow transfer passage (10), wherein the flow transfer passage (10) has a first portion (8) adjoining the prechamber gas valve (5) and a second portion (1) into which the first portion (8) opens, wherein the second portion (1) extends at least around a part of a periphery of the prechamber (3), wherein the second portion (1) has an uninterrupted peripheral surface apart from that opening (7) with which it passes into the prechamber (3).

A cylinder head for an internal combustion engine comprising a prechamber (3), wherein a prechamber gas valve (5) is fitted into a cavity of the cylinder head (2) and the prechamber gas valve (5) is connected to the prechamber (3) by way of a flow transfer passage (10), wherein the flow transfer passage (10) for a given cross-sectional area immediately downstream of the prechamber gas valve (5) is of such a length that in operation of the cylinder head (2) mounted in an internal combustion engine in a compression stroke of the combustion process propellant gas which flow out of the prechamber gas valve (5) forms a gas cushion at least in a first portion (8) of the flow transfer passage (10), that adjoins the prechamber gas valve (5).

To meet both a request to improve the thermal efficiency in medium load operation of an engine and a request to suppress knocking in high load operation of the engine, the engine includes a main combustion chamber including a cylinder block, a cylinder head, and a piston; a pre-chamber having a plurality of injection holes that open into the main combustion chamber; and a spark plug that ignites an air-fuel mixture in the pre-chamber. A compression ratio of the main combustion chamber is not less than 14 and not more than 24, an aperture ratio, which is the ratio of a total cross-sectional area of the plurality of injection holes to a volume of the pre-chamber, is not less than 0.0078 mm.sup.-1 and not more than 0.0145 mm.sup.-1, and the volume of the pre-chamber 15 is not less than 0.0430 cm.sup.3 and not more than 0.5631 cm.sup.3.

Internal combustion engine comprising at least one cylinder and a piston supported for repeated reciprocal movement in the cylinder so as to define a combustion chamber of an engine bore diameter A-A, the internal combustion engine further comprising an ignition device arranged in said cylinder having an igniter portion and an fuel injector which are both arranged in a pre-chamber, wherein the pre-chamber comprises a plurality of orifices for providing fluid communication between said pre-chamber and the combustion chamber, and wherein the plurality of orifices are of an overall orifice area so that the ratio between the overall orifice area and the engine bore diameter A-A ranges from 0.01 mm to 0.2 mm.

A cylinder head for an internal combustion engine comprising a prechamber (3), wherein a prechamber gas valve (5) is fitted into a cavity in the cylinder head (2) and the prechamber gas valve (5) is connected to the prechamber (3) by way of a flow transfer passage (10), wherein the flow transfer passage (10) has a first portion (8) adjoining the prechamber gas valve (5) and a second portion (1) into which the first portion (8) opens, wherein the second portion (1) extends at least around a part of a periphery of the prechamber (3), wherein the second portion (1) has an uninterrupted peripheral surface apart from that opening (7) with which it passes into the prechamber (3).

Auxiliary chamber type internal combustion engine has a main combustion chamber and an auxiliary chamber having an injection port through which the main combustion chamber communicates. The auxiliary chamber has a passage sectional area which is smoothly decreased toward the injection port. Further, the engine has a fuel injector injecting a fuel into the auxiliary chamber; an ignition plug igniting the fuel in the auxiliary chamber; and a swirl generating portion swirling a gas in the auxiliary chamber. The swirl generating portion swirls only the gas flowing into the auxiliary chamber from the main combustion chamber.

A system includes an engine having a main combustion chamber and a prechamber containing a spark plug. The prechamber is in fluid communication with the main combustion chamber through at least one orifice. An engine intake line provides intake air to the engine. An engine exhaust line receives exhaust gases from the engine. An exhaust gas recirculation line transports a portion of the exhaust gases from the engine exhaust line to the engine intake line, forming an exhaust gas recirculation loop through the engine. The system includes a reformer having a reactor containing a catalyst-coated substrate. The reformer generates a gaseous reformate from a fuel. The system includes a prechamber feed line to transport a stream of the gaseous reformate from the reformer to the prechamber.

Described herein is a combustion pre-chamber apparatus for a main combustion chamber of an internal combustion engine that includes a body that defines an internal combustion cavity. The apparatus also includes at least one orifice that extends through the body. The at least one orifice includes a first end open to the internal combustion cavity and a second end open to the main combustion chamber. The first end is bigger than the second end.