REVOLUTIONARY INVENTION

Otago Daily Times, Issue 21361, 15 June 1931, Page 14

REVOLUTIONARY INVENTION

DUPLEX PISTON VALVE N.Z. COMPANY’S BRIGHT PROSPECTS A REMARKABLE MACHINE. (From Oub Own Correspondent.) LONDON, April 24. A number of Ncav Zealanders who have had no return for their £15,000 of capital for a number of years should be very happy people in the not distant future. They are financially concerned with an invention which should, Avithout exaggeration of any kind, revolutionise internal combustion engines.

The completed model stands in a railAvay arch belonging to an engineering firm someAvhere in London. The representatives of the company—the Duplex Piston Valve (N.Z.), Ltd.—have been in London for three years. Four separate engines have been built and tried out. As the principal inventor expresses it, “ They have made a thorough search for niggers in the wood.” They have found them in abundance. Difficulties have been faced and overcome. Each stage of the invention has been patented, with the idea of preventing any subsequent dispute. These patents have been expensive, and they have not been obtained expeditiously. Changes have had to be made in the design until hoav the completed engine is such that, with all its efficiency, the manufacturers who take it up will not need to make very expensive alterations in their plant and tools. “ The valve can be produced by relatively unskilled labour on any ordinary tool equipment,” as Professor A. M. Loav, the eminent consulting engineer and research physicist, remarks. It has been my privilege to examine a number of ucav machines and inventions for which a great future was promised. The talking picture, for instance, but even that in the early days Avas a poor thing. Other excellent inventions by Ncav Zealanders have not gone ahead because those who should take them up would not themselves make much money out of them. This Duplex Valve is on quite another footing. The company’s representatives are Avise to keep silent in this country for the present. 'A machine that can. so greatly reduce running costs and so enormously increase power and efficiency Avith the same amount of fuel is a thing to be desired. If the valve is to be fitted to eA T en 1 per cent, of the engines of the future—and it certainly puts the present type of valve entirely out of date—the Ncav Zealand company has wonderful prospects.

It Avas a cold, damp morning yesterday. The iigav model had been motionless for three days. Three revolutions of the handle started the engine. In a few moments it was going 2000 revolutions a minute, with a medium six horse poAver load on in the shape of a fan. The exhaust pipe near to the cylinder could be touched for a second or tAvo, and the exhaust gases at the end of the pipe were quite cool. Complete combustion had been acquired. The engine is wonderfully silent. A MYSTERIOUS TWIST. '

The new valve does aAvay with the poppet valves. Instead of these there is a solid piston of steel about a foot in length. By an ingenious but simple device, this is made to go backAvards and forwards in its sleeve. But at the same time it is subjected to a rotary motion as well. A large port through the piston allows the explosive mixture to go into the main cylinder at a speed quite unattainable Avitji the poppet valves. Moreover, the gas is subjected to some mysterious tAvist, and arrives in the cylinder in finer particles than it does in present maVhines. According to the technical phrase, there is no “ wire-drawing effect,” In ordinary language, this means that the gas mixture finds its place in the cylinder comfortably and without stress and strain and friction in an infinitesimal fraction of time. The explosion takes place, and because of the fineness of the particles there is complete combustion. As # the main cylinder begins to rise to eject the burnt gases, *an aperture through the piston valve is exposed to allow them to go out —again without stress and strain. At the outlet there is again the spiral effect on the exhaust gases, and this probably has the* effect of hastening them along the exhaust pipe. One other secret of the machine is this: The piston valve in its reciprocate ing motion makes Avhat may be as a “ comparative pause ” at each end of its stroke. It is just at these times that the ports are open to the full, for the intake on the one hand and the outlet of gases on the other hand. PROFESSOR LOW’S REPORT. - Professor Low, in the course of his favourable report on the demonstration engine Avhich has been designed in accordance with the company’s patents, says: “The speed at AA'hich the port openings are obtained gives a torque curve which should compare more than favourably Avith any multi-cylinder engine of comparable size and fuel consumption. “ I consider that the main principle of the design could be applied to motors of the Diesel type without any appreciable increase in cost over those of poppet valve design. FOR AVIATION USE.

“ During a brief running test it was to be observed tliat although no special arrangements were made to ensure satisfactory carburetion at varying engine temperatures there was a complete lack of the inlet condensation which has so often mitigated against the success of the ‘ piston or sleeve ’ engine. For this reason it would appear that the heavier classes of oils could be used in a Duplex motor designed under these patents. This is worthy of note in vieAV of the possible application of the design to colonial and aviation use.

“ Although the experimental motor is of the single cylinder type without any real balancing precautions, the running was quite exceptional over a wide range of speeds and a degree of silence was maintained which could not be equalled by any ordinary engine. “ In my opinion, it would be possible to design a commercial type of engine under the principles of this invention which would maintain its tune over long periods, would be silent under conditions of rather rough manufacture, and which would be able to compete most satisfactorily with existing design. “ I* have formed a high opinion of the of this engine.” ROLLS-ROYCE RESULTS. It needs little imagination to see the advantages of this new invention. The exhaust gases of some of the finest aeroplane engines, for instance, are so hot as to bo able to raise the metals to a white heat. The finest metals have been produced to resist this heat. With the Duplex valve installed the hand could be held in the path of the exhaust gases at a very short distance from the outlet port. Even at the highest speeds no flame is emitted. The valve will need no more attention than other parts of the motor engine. It will remain constant throughout the life of the engine, requiring no adjustment. Its constructional cost will be very little, if at all, higher than that of the ordinary poppet valve type and much less than that of the sleeve valve. The official graphs prove that under load the engine develops power and M.E.P. curves of surprising figures, and this in addition to notable silence, lack of vibration, and economy. The rating of a single cylinder, according to the