THE DUO HEAVY-OIL CARBURETTER.
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A French Production Which Permits of Starting on Petrol and of a Gradual Change to Heavy Oil.
rinHE EMPLOYMENT of heavy oils in motor vehicle engines nearly always necessitates the use of a separate petrol carburetter for starting plirposes, in addition to the special carburetter for vaporizing the oil. A new carburetter
• has just appeared in Paris in which the two fuels may be used either separately 43-,: in conjunction. Designed by a Polish engineer, M. Chiilovsky, the carburetter is to be known as the " Duo."
The vaporizing chamber for the it is jacketed and heated by the engine exhaust and the jacketing is traversed by four pipes conveying the main air supply fo..7 the oil portion of the carburetter. The main air is thus thoroughly heated before it, reacheg the fuel jet.
The vaporizing tube is fitted with a liner, which is slightly smaller in diameter than the tube itself and pierced all round with a number of small holes, through which the extra air reaches. the mixture.
The petrol portion of the appliance crmprises an ordinary type of horizontal single-jet carburetter with an entirely separate main air inlet.
A cylindrical throttle is fitted, and this is so arranged that, when slightly opened, petrol vapour only is admitted to the engine. When further opened, petrol and oil vapours are admitted to gether, whilst at throttle, the petrol portion of the carburetter is entirely
shut off and the engine runs on heavy oil alone. In order to allow for the use of oil fuel only at small throttle openings, is secondary throttle of the butterfly type is introduced between the flange of the carburetter itself and the inlet manifold. The control levers for these two throttles are clearly shown in the illustration at the foot of this page. The heavy-oil jet is of the diffuser type in which air enters the vaporizing chamber together with the fuel spray.
The whole carburetter is made in bronze, and the workmanship is exceed
ingly good All parts are rendered most accessible. The jets can besemoved and cleaned, and the entire carburetter taken down and re-assembled in the shortest possible time.
A strong point in favour of the Duo carburetter is the fact that the liner of the vaporizing chamber is insulated all round by a layer of air from the actual hot jacketing itself. One of the troubles. attached to heavy-oil vaporizers is the fact that the fuel tends to carbonize on the hot interior surface a the chamber, and this should be avoided in the Duo by the presence of the entering extra air in the space between the liner and the jacketing, this air acting as an insulator.
The Duo carburetter is made in Switzerland and marketed in France by Messrs. L. Raymond Levy et Cie, 177, Faubourg Poissonniere, Paris. r The carburetter has already earned a good reputation in Central Europe Representation in this country for the sale of the carburetter has not yet been arranged.