Gaseous fuel internal combustion engines powered with a lean mixture of gaseous fuel and air may comprise a pre-combustion chamber (also referred to as pre-chamber) per cylinder for ignition purposes. Particularly, large-bore engines may benefit from those pre-chambers as it is otherwise difficult to consistently achieve complete and thorough combustion using lean fuel air mixtures.
Typically, such a pre-chamber is fluidly connected to a main combustion chamber of a respective cylinder via a riser channel and a plurality of flow transfer channels. The flow transfer channels and the riser channel allow the flow of the lean mixture of gaseous fuel and air from the main combustion chamber into the pre-chamber during a compression stroke. Enrichment of the lean mixture in the pre-chamber may be effected by providing a small quantity of (gaseous) fuel into the pre-chamber via a separate fuel feed passage, for example during the intake stroke. The enriched mixture is ignited in the pre-chamber by an igniter such as a spark plug. The ignition of the enriched mixture causes a flame front of hot gases that propagates from the pre-chamber via the flow transfer channels into the main combustion chamber. Thus, the lean mixture in the main combustion chamber ignites and burns, and thereby, expands against a movable piston that drives a crankshaft.
For example, JP 2014-129788 (A) discloses a pre-combustion chamber type gas engine. Here, the pre-combustion chamber type gas engine includes a pre-combustion chamber and a main combustion chamber that are in communication with each other through an injection hole disposed on a pre-combustion chamber cap. A combustion flame generated in the pre-combustion chamber is injected into the main combustion chamber through the injection hole so as to combust mixed air inside the main combustion chamber. The injection hole has a diameter that decreases gradually from an inlet into which the combustion flame flows toward a throat section having an opening diameter that is smaller than an opening diameter of the inlet, and has a Laval nozzle shape whose diameter gradually increases from the throat section toward an outlet from which the combustion flame flows out.
The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems.