The present disclosure relates to a method for operating a combustion engine. A main amount of gas fuel is fed via a pre-chamber into a main combustion chamber. An ignition quantity of gas fuel is fed into the pre-chamber before the piston reaches the upper dead center to form an air-gas fuel mixture in the pre-chamber, which is fatter than in the main combustion chamber. The air-gas fuel mixture in the pre-chamber ignites itself. The air-gas fuel mixture in the main combustion chamber ignites through the self-ignited air-gas fuel mixture in the pre-chamber.

An engine includes a main combustion chamber; an intake duct configured to provide a lean fuel-oxidizer mixture to the main combustion chamber; a pre-chamber in fluid communication with the main combustion chamber, the pre-chamber including an ignition energy source operatively coupled to the pre-chamber, and a heating element in thermal communication with the pre-chamber; and a controller operatively coupled to the ignition energy source and the heating element. The controller is configured to initiate combustion of the lean fuel-oxidizer mixture in the main combustion chamber by activating the ignition energy source, and heat fuel and oxidizer in the pre-chamber via the heating element to a temperature sufficient to produce hydrogen peroxide (H.sub.2O.sub.2) in the pre-chamber.

An engine system employs a pre-assembled and/or removable cartridge. In another aspect, an ignitor, a fuel injector and an air inlet valve are all accessible from a top of a cartridge even after assembly of the cartridge to an engine cylinder head. A further aspect positions centerlines of an ignitor, a fuel injector and an air inlet valve angularly offset from each other and also angularly offset from a vertical centerline of a cartridge to which they are mounted.

An engine system employs a pre-assembled and/or removable cartridge. In another aspect, an ignitor, a fuel injector and an air inlet valve are all accessible from a top of a cartridge even after assembly of the cartridge to an engine cylinder head. A further aspect positions centerlines of an ignitor, a fuel injector and an air inlet valve angularly offset from each other and also angularly offset from a vertical centerline of a cartridge to which they are mounted.

An internal combustion engine including an igniter disposed at least partially within an aperture defined in a housing of the engine, the igniter having a body including a tip supporting portion and having a tip extending from the tip supporting portion. A cooling sleeve is disposed around the tip supporting portion, and the cooling sleeve defines a path of heat transfer between the tip supporting portion and the housing. The engine may be a rotary engine. A method for cooling an igniter of an internal combustion engine is also discussed.

An ignition system for a vehicle internal combustion engine (12) has a capsule defining a pre-chamber (136), an ignition fuel supply system (500) configured to inject an ignition fuel to the pre-chamber to create an ignition fuel-air mix in the pre-chamber, an ignition surface (137) within the pre-chamber, the ignition surface being defined by an interior surface of the capsule and configured to be contacted by the ignition fuel in the pre-chamber to thereby ignite the ignition fuel by hot surface ignition, and at least one jet nozzle (152). The ignition fuel is characterised by having a carbon content by mass less than 65%, a hot surface ignition temperature less than 500 deg C., and a volumetric energy density (LHV) greater than 18 MJ/L. The at least one jet nozzle is configured such that ignition of the ignition fuel by contact with the ignition surface causes at least one of hot gases, partially combusted fuel and flames to leave the pre-chamber through the at least one jet nozzle.

An internal combustion engine including an igniter disposed at least partially within an aperture defined in a housing of the engine, the igniter having a body including a tip supporting portion and having a tip extending from the tip supporting portion. A cooling sleeve is disposed around the tip supporting portion, and the cooling sleeve defines a path of heat transfer between the tip supporting portion and the housing. The engine may be a rotary engine. A method for cooling an igniter of an internal combustion engine is also discussed.

An ignition system for a vehicle internal combustion engine (12) has a capsule defining a pre-chamber (136), an ignition fuel supply system (500) configured to inject an ignition fuel to the pre-chamber to create an ignition fuel-air mix in the pre-chamber, an ignition surface (137) within the pre-chamber, the ignition surface being defined by an interior surface of the capsule and configured to be contacted by the ignition fuel in the pre-chamber to thereby ignite the ignition fuel by hot surface ignition, and at least one jet nozzle (152). The ignition fuel is characterised by having a carbon content by mass less than 65%, a hot surface ignition temperature less than 500 deg C., and a volumetric energy density (LHV) greater than 18 MJ/L. The at least one jet nozzle is configured such that ignition of the ignition fuel by contact with the ignition surface causes at least one of hot gases, partially combusted fuel and flames to leave the pre-chamber through the at least one jet nozzle.

An internal combustion engine having a combustion chamber incorporates a fuel conditioner and injector employs a vessel having a wall exposed within the combustion chamber to be heated by combusting fuel. The vessel encompasses an expansion chamber and has at least one open fuel injection passage through the wall into combustion chamber. An inlet conduit receives liquid fuel at a predetermined pressure from a fuel delivery system. A nozzle interconnects the inlet conduit and the expansion chamber. A pin operably seals the nozzle for timed injection of liquid fuel into the expansion chamber. An operator actuates the pin from a closed position sealing the nozzle to an open position placing the fuel injection volume in fluid communication with the expansion chamber. Liquid fuel injected into the expansion chamber at a predetermined time is simultaneously adiabatically heated, and pressurized to a state above a critical point using heat in the vessel wall and self-injects through the at least one open fuel injection passage into the combustion chamber of the engine.