Patent ID: 7654072

Claim:
An engine unit, particularly for urban transport, comprising: an engine supplied with a compressed gas and having an expansion chamber provided with a cylinder and piston arranged for completing cyclically a power and an exhaust stroke at each double stroke; a liquid gas tank in communication with the engine; a liquid fuel tank; means for gasifying the liquid gas, which are interposed between the liquid gas tank and the engine for obtaining compressed gas, the gasifying means comprising a heat exchanger for a starting gasification of the liquid gas in communication with the liquid gas tank; a close housing wherein a gasification chamber is formed, the gasification chamber being in fluid communication with both the liquid fuel tank and the heat exchanger for the combustion of the liquid fuel with the oxygen of the compressed gas, the gasification chamber being further in fluid communication with the expansion chamber through a port so that the entire gas mixture comprising compressed liquid gas, gaseous products and by-products of combustion process passes into the expansion chamber to do useful works; an intake manifold and an intake duct placed between the port of the gasification chamber and the expansion chamber, wherein the intake duct puts the expansion chamber in communication with the intake manifold through a respective intake valve; and controlling means provided for opening said intake valve for a first duration in such a way that the piston of the engine is pushed by a constant pressure of the gas from the gasification chamber, and for closing said intake valve for a second duration in such a way the piston of the engine is pushed by gas expansion, wherein the gasification chamber is split into a first gasification chamber and a second gasification chamber for combustion of the liquid fuel with the oxygen under conditions of saturated steam and overheated steam respectively, each of said first and second gasification chambers comprising a respective pilot igniter.