STEAM AS AN AID TO COMBUSTION.
Page 9
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Some Details of an Interesting French Device for the Automatic Admixing of Water Vapour with the Explosive Mixture.
THE mixing of a small quantity of water vapour with the explosive mixture in the petrol engine is considered by many experts greatly to improve the combustion and to assist in the economical use of the fuel employed.
One does not-need to be a Bachelor of Science to appreciate the fact that in an internal-combustion engine of any type there is a very high temperature in the cylinder at thet moment of the explosion. In fact, in the case of the petrol engine this temperature is something above the melting point of iron. " Explosion " is a ,,ery good word to use for the results whichoccur when the mixture is fired, as the piston is forced to the bottom of the cylinder in the same way as.a shell is propelled from a gun. The steam-engine acts very much more softly arid the pressure is maintained more evenly during the power stroke; and it is reasonable to believe that tin, combination of Steam and the explosive mixturetnay prove very beneficial.
Many persons have noted that a petrol engine, often runs morefreely and smoothly in the evening than during the day, and the scientific reason for this is probably that the air is more humid, and thus promotes better carburation. In order to obtain this improved running during the day time, as well as at night, several instruments for artificially moistening the mixture have been put on to the market, but most of these have failed becausethe amount of water vapour added to the mixture varied, and thus caused uneven running and misfiring.
We have received particulars of an interesting French invention known as
the Auto-injectir M.M. This apparatus, although it has been on the market for less than two years, is in use on some
5,500 motor, vehicles in France. It is stated to give remarkable economy in petrol consumption, varying from 15 per cent. to 40 per cent., and an increased road speed averaging 18 per cent. It is also said to prevent, the deposition of carbon in the engine and, by slightly retarding the speed of flame propagation, makes the engine more elastic and prevents knocking. Water injection is onployed in certain engines using paraffin as a fuel, and is found most beneficial in preventing the detonating which often occurs when this fuel is employed.
In the case of the M.M. device, a tube, which admits vapour at low temperature and at atmospheric pressure, is placed in the inlet pipe of the engine and pene trates it at right angles to its axis, occupying about two-thirds of its diameter. This formsone of the funda mental points of the invention. The quantity of cOmbustible gas admitted in the cylinder is in no way altered by the presence of this tube, but instead of a full charge of petrel vapour, mixed with its correct proportion of air, there is something like 70 per cent, of this vapour and 30 per cent. of water vapour. The introduction of this water vapour does not weaken the mixture or cause it to give less power. On the contrary, at the moment of the explosion it is converted intu-steam at high pressure. This
steam, apart from assisting to a slight degree in moving the piston, is said to be partially decomposed by the high temperature, with the result that the liberated oxygen assists complete combustion.
A short description of the apparatus may be of interest ; it is shown diagrammatically in two of the illustrations The tank of water (R), containing about. one gallon, is fixed to any convenient part of the vehicle on the exhaust side, whilst the water delivery pipe (F) is clipped to the exhadkt pipe for the greatest length practicable, and is then connected to the
bottom of the injector (C),';" which is bolted to the dash or to the engine. The pipe (T) conducts any excess. of water
back to the reservoir, The injector is arranged so that it is absolutely impossiblelfor water to reach the carburetter or the cylinders.
The water heated by the exhaust pipe arrives in the based f the injector, which is shown inqhe small diagram arid illustration.. Air:isi drawn by the suction of the engine -through the-ports (F,), and thus indlices 'flow of hot -water from the jet (G). Theiair, -passing thisrjet of hot water, becomes richly charged -With Water vapour the mixing of .air and vapour being completed in a chamber above the jet.. The air and vapour, then passes through the automatic valve (C) and, by. way of the tube (N), into the
inlet pipe of the engine.
The automatic valve (C) is an important feature of the invention ; the valve is. normally held open by a spring regu• hated by ainuttand a lockout. At low engine speeds it is'held shut, owing to the high degree of vacuum in the inlet pipe, but as the throttle is opened this vacuum diminishes, and at medium speeds the valve rises and falls with each suction stroke. At normal road speed the valve is always open. Once adjusted it responds automatically to the needs of the engine, allowing the admission of the maximum amount of water vapour at high engine Iieeds and cutting off the whole of the water vapour at low speeds. This is an interesting point, as the admission of water vapour at low engine speeds is apt to cause misfiring and sometimes stoppage of the engine. . The price of this interesting little device, taking the rate of exchange into consideration,. would be in the neighbourhood of £9 to £1.0 retail, and if it does ail that is claimed for it, it would repay its cost very rapidly.
The device, although patented all over the world, is as yet but little known in this country, for which the manufacturers are willing to arrange the selling
rights. In this connection those interested should communicate with Mr. A. Welsh, 79, Rue des Carmes, Rouen, who is authorized by the manufacturers ' to make the necessary arrangements.