Hydrogen-fueled four-stroke internal combustion engine

A method of operating a sparked reciprocating four-stroke internal combustion hydrogen-fueled engine comprising an engine casing, a crankshaft rotatable about a crankshaft axis, a cylinder arranged inside said engine casing, a piston arranged inside said cylinder to movably reciprocate along a reciprocating axis between a top dead center (TDC) position distal from said crankshaft and a bottom dead center (BDC) position proximal to said crankshaft and operatively connected to the crankshaft such that the reciprocating piston imparts a rotational movement to the crankshaft, a combustion chamber defined within said cylinder between the engine casing and a head of the piston opposite said crankshaft, an intake valve, an exhaust valve, a hydrogen injector configured to directly inject hydrogen into said combustion chamber, a water injector configured to directly inject water into said combustion chamber;

• a spark or glow plug, and an engine control unit, configured to implement the steps of the method, said method comprising at each four-stroke cycle the steps of:
• a) injecting hydrogen at a third timing from 180° to 100° before TDC during compression stroke into the combustion chamber through the hydrogen injector,
• b) injecting water at a second timing from 110° to 90° before TDC during compression stroke into the combustion chamber through the water injector, and
• c) injecting hydrogen at a first timing from 20° before TDC during compression stroke to 20° after TDC into the combustion chamber through the hydrogen injector.