CARBURETTERS AND FITTINGS.
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A Résumé of Recently Published Patents.
THE INGENIOUS carburetter which , is described in specification No 190,4.32 by Louis Renault, has two sets of jets. There is a .single jet, for slowrunning purposes, and a multi-jet, for normal working. The jets which form the latter are arranged in a ring : they draw their fuel through an annular passage and a tubular duct from an aperture of specified area. The tubular passage is equipped with an air inlet pipe of small dimensions, the' inner end of which is subinerged when the main multi-jet is not in actual use. The arrangement is a familiar one; we need not enlarge upon it now.
The single, slow-running jet projects into a venturi tube, ',which may be moved axially, so as to vary the intensity of the suction on that jet. In its extreme position, when maximum suction is desired, and the venturi is located so that its narrowest part is round the jet, it also acts as a closure for the main jets, which are thus automatically rendered inoperative when the slow-running .jet is in full use. The venturi is arranged to move in conjunction with the main throttle, being actuated by a rod which is coupled up to the accelera The important features of the carburetter which is described in specification No. 195,125, by A. D. Patterson, are well shown in the accompanying dlaa grammet.ie sketch, although we should
• add that some illuatrations showing • practical applications of the principles involved are also included in the specification. The inventor's object is to provide novel compensating means for obviating what is known as " flat spot," which is a phenomenon occurring at periods in most carburetters provided with Miele for supplying, 'in addition to the mixed fuel and air, via the main jet, a rich mixture for starting and slowrunning purposes in 'advance of the throttle valve.
This flat spot is due to the fact that, on opening the throttle to admit the main charge of mixture, the volume of air passing through the choke tube does not create sufficient vacuum to cause a charge of correct proportions `to issue from the main jet; whilst it also dilutes the slow-running mixture suddenly or to too great an extent.
The inventor's object is achieved by supplying a charge of liquid fuel only,
undiluted by any addition of air, to the it2
induction pipe or its equivalent, at a point adjacent to the point of issuance of the starting or slow-running mixture. This supply of fuel is provided on the carburetter side of the throttle, but so • far as possible from the main jet., and it issues into the induction pipe under 1 ign Suction. The main jet is provided with a special diffuser element, so 'that there are two means for the supply of air to that jet. It is claimed that the double dilution of the main supply, taken in conjunction with the supply of undia luted fuel, will properly overcome the objectionable "flat spot."
Specification Noa195,209, by E. Pope, refers to carburetters of the surf ace type. There are three sets of plates located immediately behind the shutter-like throttle valve, in the inlet passage to the carburetter. The plates are arranged, one above another, so-as, in a way, to stratify the air as it enters the carburetter. They:are disposed, too, so that the path which ,the air follows is a zig-zag one being directed first down, then up, then down and up again. Fuel is allowed to drip on to the top of the centre set of plates, and to dribble down past all of them in much the same way that water drips down the slats of, a surface condenser for steam.
The vaporizer which is described in specification No 195,232, by S.'Kintigasa, and which is designed to facilitate the use of heavier fuels than petrol, in an ordinary petrol engine, is in effect a vertical extension of the combined induction and exhaust manifolds, the 4a.x tension of the former being disposed within that of the latter, so that it may' receive heat therefrom. Further to facilitate this desirable exchange of heat, conducting pegs are fixed so that they project from the exhaust pipe into the induction pipe. The proportions of exhaust gases which pass' along the vaporizer are regulated by valves, of which there is One on the main exhaust manifold, and one on the extension. Opening the former and aipsing the latter reduces the amount of heating which is transferred to the incoming gases, and vice versa.
It has, on many occasions, been urged that inadequate attention is paid by engineers to the design of the filters whichare provided in the fuel-feed' apparatus of a motorcar or lorry.That complaint is well on the Way to an early demise, if many more patent specifications like No. 195,200, by William Fell, appear. It comprises nine full and closely printed pages, as well as many -illustrations, and is' devoted entirely to the design of a filter for the purpose 'already named. The inventor uses chamois leather as the filtering medium, and claims, in his design, to have surmounted objections which have hitherto always existed whenever that particular medium has been employed. To that end he provides a means which ensures a uniform utilization of the whole area
of the filtering medium, a self-cleaning action of that medium, and a maximum efficiency and permeability of the same, by keeping it automatically and permanently taut. Replaoement and cleaning of the filter and tirefiltering mediuni are facilitated, and the whole apparatus is mountedin -a glass case.
Several construction are described and 'illustrated in the specification. Reference need only be made here to one of them. The eliamois leather is shaped so as to be circular in form, and in cross-section like the letter W, the top outer edges being clipped to 'the top of the body of the filter, the central apex' . of the W attached to a binding post; which is hollow and alto serves, as inlet for the fuel, which enters from below, while the two V's of the W are held out, and the material ef.the filter kept taut, by a light coil spring which, at its other end, bears against the inside of the caver of the filter • Specification No. 195,124 shows a design for a six-wheeled vehicle of -tho tractor-trailer' type, in which provision is made for the articulation of the colnbined unit in a vertical_ plane.