A nozzle for a prechamber assembly of an engine includes a nozzle body which is hollow and includes an outer surface, an inner surface, and an orifice surface. The outer surface defines an outer orifice opening, and the inner surface defines an interior chamber and an inner orifice opening. The orifice surface defines an orifice passage extending between, and in communication with, the outer orifice opening and the inner orifice opening. The orifice passage is in communication with the interior chamber via the inner orifice opening. The nozzle body includes a coolant surface which defines a coolant passage within the nozzle body. The coolant surface includes an orifice interface portion disposed adjacent the orifice surface such that the orifice surface and the orifice interface portion of the coolant surface are in heat-transferring relationship with each other.

A pre-chamber assembly of an internal combustion engine includes a supply channel configured to supply air and fuel into a pre-chamber, at least one transfer passage configured to couple the pre-chamber with a main combustion chamber, and a riser passage between the pre-chamber and the transfer passage. The riser passage is oblique relative to a longitudinal axis of the pre-chamber assembly. An ignition means and the supply channel are arranged on a proximal end of the pre-chamber assembly.

Systems, devices, and methods described herein provide one or more radical chemicals generators (RCGs) and/or mini-chambers (M-Cs) that can be used to provide enhanced radical ignition (ERI) in an internal combustion engine. RCGs as described herein can include quenching systems (QSs) that can be configured to quench a flame of combustion products to produce a jet of partial combustion products containing radical species (RS). The jet of partial combustion products can be injected to a main combustion chamber (MCC) of an engine to induce ERI. ERI can proceed under leaner fuel conditions and lower temperatures compared to those needed for conventional thermally induced, fuel oxidation chain initiation reaction processes.

A pre-chamber ignition apparatus for an internal combustion engine comprising an apparatus body associable with the cylinder head of an internal combustion engine for communicating with a combustion chamber of the cylinder head through at least one connection hole, a microwave ignition device for generating microwaves to cause ignition of an air/fuel mixture in a pre-chamber formed within the apparatus body. The apparatus body comprises an upstream portion configured to allow the housing and fixing of the microwave ignition device and a hollow downstream or head portion, delimiting the pre-chamber, in fluid communication with the combustion chamber. The downstream portion is provided with at least one connection hole. The hollow downstream portion includes a reflection wall opposite the microwave ignition device and shaped to receive and concentrate microwaves generated by the microwave ignition device and/or a resonance cavity for the mixture contained in the pre-chamber thereby amplifying the combustion in the pre-chamber.