New Design of Combustion Head
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Q ATISFACTORY turbulence, elimi6%3 nation of shock waves, and improved cooling, are the advantages claimed for a combustion chamber for petrol engines shown in patent No. 590,006, by M. Julien, Toulouse, France.
The drawing shows an air-cooled engine embodying the new head, but this is by way of example only. The combustion chamber is hemispherical, although the section appears otherwise owing to the presence of the valves, The chamber is less in diameter than the cylinder, thus leaving a shoulder, which gives a " squish " effect at top dead centre. The effect may be increased by providing a small boss on the piston crown which enters the combustion space.
A feature of the design is that the stroke is shorter than normal, being less than the bore. The valves are of conventional pattern, but their springs are of the torsion-rod type and take the place of the more ordinary rocker pivot-pins.
AUTOMATIC CHOKE CONTROL FOR CARBURETTERS
PA.A CAR BURETTER fitted with a thermo-responsive choke control is shown in patent No. 589,637 by Bendix Aviation Corp., South Bend, Indiana, U.S.A. The device is claimed to pro
vide the correct starting richness down to temperatures as low as minus 25 degrees.
The main operating member is a thermally responsive device (1) attached to the exhaust. This opens or closes the choke for all normal temperatures, but is restrained in respect of the closed position by a stop (2). The position of this stop is determined by a qtiadrant (3), which is in turn governed by a thermal strip (4); this is shown in the position corresponding to an excessively low temperature, in which it gives the maximum closure of the choke butterfly valve.
The valve itself is pivoted out of centre, so that, when the engine starts, the inrush of air tends to open it. This might result in too sudden an opening, and, to prevent this, another thermal A38
strip (5) arrests the movement until the temperature has risen enough to clear it from the quadrant (6).
SOLUTION FOR REMOVING CARBON DEPOSIT
rARBON deposit such as is formed in
internal-combustion engines is a complex mixture, consisting of insoluble pitch, silica particles (probably road dust) and resinous matter derived from the engine oil. Lead compounds from anti-detonants may also be present. A solution claimed to dissolve this mixture forms the subject of patent No. 590,123, from S. Lunt and N. Drey, 13, 5th Avenue, Bridlington, Yorks.
Observation has shown that if the resinous matter can be dissolved, the rest of the mixture will fall away easily. To this end, it is proposed to use a mixture of naphthenic acid, naphthalene, cresol, caustic soda and sodium metasilicate. This mixture, when sprayed on the deposit, acts as an emulsifier, and loosens the carbon so that it can be washed off by a water jet. In spite of the presence of strong alkali, its concentration is kept just below that which will attack light alloys.
PROGRESS IN TORQUECONVERTER DESIGN FROM the Bendix Aviation Corporation, South Bend, Indiana, U.S.A., come, in patent No. 590,157, details of an improved type of torque-converter.
The gear comprises an input shaft which drives the vaned impeller (1) whilst the output shaft is driven by the outer vaned member (2), with which are incorporated other vaned members (3 and 4). Included also in the fluid circuit is a pair of reaction blade-rings (5). These are so shaped that a high rate of fluid flow over them tends to reverse the direction of running with respect to the main turbine.
In normal operation, the gear remains in the state, shown, that is, capable of giving a speed reduction withincreased torque. As the speed rises, however, the point is reached when the reaction vanes reverse; when this happens, they lock ball-ended toggles (6) which, by their a'ngular movement, retract the vanes bodily to the left, withdrawing them from the fluid path into chamber 7. The result is to alter the flow so that the gear then drives at a 1-to-1 ratio. An increase in the transmitted torque above a certain value reverses the process, and brings the vanes back into the operative position.
A PISTON WRIITNHGUSNSPLIT TOP
I MPROVEMENTS in pistons and their rings form the subject of patent No. 589,708, which comes from Specialloid, Ltd., C. Russell, and E. Graham, all of Friem Park, London, N.12.
Several types are described, one of which is shown in the drawing. In this case, the top rings (1) are endless and are cast or forged into the light-alloy piston during manufacture. The rings are made from a high-nickel iron containing 36-50 per cent, of nickel_ This type of alloy, better known as Invar, has a coefficient of expansion so low that it may be disregarded.
When the pistonis cold, the rings stand slightly proud, but as the piston expands they will eventually approach the flush condition. A small space, not shown, would be left at the back of the rings to allow fat this expansion. The piston may also be fitted with a set of conventional split ringsat the bottom of the skirt, as shown at 2.