Abstract: This invention concerns an internal combustion engine with a combustion chamber (8) for burning the working gas in an explosion stroke and, connected to the combustion chamber (8), a pump chamber (18) which can be filled via an input orifice (181) with a driving fluid which can be ejected through an exhaust orifice (182) by the effect of the combustion gas formed during the explosion stroke; this internal combustion engine is provided with a spraying device (19, 50) with which a coolant can be sprayed into the pump chamber (18) during an implosion stroke subsequent to the explosion stroke.