A NEW FUEL FOR HIGHER COMPRESSIONS.
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A Résumé of Recently Published Patents.
AN INVENTION which has aslits object the provision of a new fuel, one which willi reduce the tendency of a petrol engine to knock, is described by General Motors Research-Corporation in specification No. 196,237. It is an American invention, and it is significant Llia,t even in that country the tendency )n fuels is, according to this inventor,
to produce lower grades of petrol in order to obtain a sufficient output to meet the increasing demand for motor Awl." This naturally involves manufacturers in reducing the compression of their engines, so that these lower grades of fuel may be used without knocking. As. the lowering of engine compression reduces the efficiency of the engine, a still greater output of fuel is required to meet the greater demands in order to be able to operate larger and less efficient engines—a sort of vicious circle,of inefficiency. The object of this invention is to overcome the difficulties by providing a means for using either low or high grades of motor fuel more efficiently, thus reducing the quantity of fuel used.
To this and a vaporizable compounded metallic element is mixed with a fuel which has as its base a low-compression motor fuel.
The drawings • which illustrate this specification show t (1) A motorear in which the sizes of engines are compared according to whether this new fuel or present-day petrol he employed, and (21 a sectional view of an engine cylinder showing the comparative sizes of combustion chambers which are needed in accordance with these different conditions.
As an example of the class of fuel to which this specification refers we may Cite one whidh consists of one-quarter of one per cent, by volume of tetra ethyl lead and 99i per cent, of petrol having a normal critical compression pressure of about 75 lb. This tetra ethyl lead dissolves in the petrol to form a fuel which has a critical compression pressure of about 160 lb. Experiments with automobiles have shown, according to this inventor, that, if the engine compression be increased to 160 lb., a treated fuel being used, and the gear ratio between the engine and the rear axle be reduced to meet the altered conditions, the mileage obtainable from a gallon or petrol is substantially twice that which would be obtained using the ordinary fuel.
• For certain commercial purposes it will probably, be sufficient th use but one part tetra ethyl lead in 2,000 parts of petrol. This mixture, used, for example, in the engine Of a commercial vehicle, would eliminate the knock which is frequently experienced when climbing hills at low speed with the. throttle fully open. It has been _found that relatively small proportionalk -kantities of the lead compound are required to increase the critical compression pressure of aviation spirit from 125 lb. to 160 lb. or more.
Other PT!' Es of Interest.
An intere.sti... prevenient on that typo of cone. elute in which the driven member is sueported independently of the means of transmission has been deB46 s'gned by the Sunbeam Motor Car Co., Ltd., L. Coatalen and H. C. M. Stevens, and is described by them in specification No. 208,754. It is claimed for this particular construction that it, allows of more extensive axial movement of the clutch centre than has hitherto been possible with clutches of this type. The clutch centre is mounted on a sleeve on the clutch shaft, and this sleeve differs from those usually employed only in that it is quite free to rotate on the shaft. There is a second hub splined upon that shaft, and connected to the clutch centres by means of a flexible disc.
Specification No. 208,837, by W. Wallace, refers to friction clutches of the multi-disc type, running in oil, and the object of the inventor is to prevent too sudden engagement of this type of clutch as the result of nnskiLful manipulation of the pedal. To this end the inertia of the lubricant is utilized. The presser plate, or. a supplementary plate, is made a fairly. close fit in the clutch casing, and the oil, which is thrown outwardly by centrifugal force, must pass between the edge of the plate and the interior of the casing as the plate moves to engage' the clutch. It will be seen that the plate and casing, together with the oil, act as a clashpot.
In that type of engine which embodies a short sleeve valve which operates within an annular space between the cylinder and the cylinder head, it has been found that the greatest resistance to movement due to the internal gas pressures occurs just before the exhaust port is opened. IL J. Howard utilizes the power exerted by the gases to operate the valve. He doges the outer end of the cylinder bore with a hollow piston head, leaving an annulus, the sectional area of which is such that the valve, which must fill it, receives sufficient end, pressure from the gases within the cylinder to overcome the frictional resistance of it working surfaces. This invention is described in specification No. 208,810.
The engine which is described in specification No. 1.89,151, by R. P. Pescara, uses the exhaust gases lo drive a compressor for the induction. The engine operates on the lour-stroke cycle and each cylinder has three valves. At the beginning of the induction stroke pure air is taken through one of these valves. Later, this valve is closed, and the cylinder filled -by means of the compressor driving a rich mixture through a carburetter. The third valve is used for exhaust.
Two forms of an interesting lubricat
ing device are described in specification No. 208,916, the patentees being Dennis Bros., Ltd., J. Dennis and C. R. Charles. A valve is located in a conduit leading from the oil reservoir to the parts which are to be lubricated, and this valve is opened by engine suction.
An improved arrangement of multithrow crankshaft is described by F. H. Royce in specification No. 208,827. As applied to a four-throw shaft, which application is naturally of most interest to readers of this journal, the cranks are arranged with alternate throws in line with one another, instead of, as is usual, Nos. 1 and 4 being in line and Nos. 2 and 3. Weights are attached at each end of the shaft for balancing purposes.
B. B. Baker supplements the ordinary semi-elliptic or quarter-elliptic spring by another quarter-elliptic which is adjustable. It is mounted on a pivot, which is a short distance from its butt end. Under the latter is a support, the height of which is adjustable, thus affording the means of adjustment for the spring. Ris invention is desCribed in specification No. 208,750.
A combined disc and spring wheel has been patented by J. F. Fairley, and is described by him in specification No. 208,650. The wheel is built up of an inner disc and an outer rim, which are separated from, and connected to, one another by U-shaped springs.