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A Double-seated Exhaust Valve p ATENT No. 567,948 comes from the

18th May 1945, Page 36
18th May 1945
Page 36
Page 36, 18th May 1945 — A Double-seated Exhaust Valve p ATENT No. 567,948 comes from the
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Brush Electrical Engineering Co„ Ltd., and C. B. Dale, both of Loughborough, and shows a design of exhaust valve for a two-stroke engine, the chief feature being a means for obtaining a greatly increased port area. Although intended cliefly for twostroke units of the " Kadenacy " type, it is stated that the valve could also be used for four-stroke engines.

The engine works on the uniflow principle, the air entering from a belt

at stroke-botto, whilst the exhaust departs from a port in the cylinder head. The exhaust valve is operated in the usual way, but its head consists of a short tubular member provided with an upper seating (1). and a lo*er one (2), both of which co-operate with seatings in the cylinder head.

The exhaust port (3) is formed into a belt which completely surrounds the valve, and when the latter opens, a lull-bore passage is made at both the upper and lower seatings. The interior space of the valve head forms part of the compression space of the cylinder. The valve is slightly sunk into its seating, so that it does not actually open until it has moved a short distance; this feature is said to provide a rapid opening motion.

A STARTER FOR LARGE ENGINES

THE increasing size of modern vehicles is approaching the point at which battery-operated starters are ceasing to_ be practicable, and patent No. 567,954 shows a scheme in which a small petrol engine is employed for the purpose. The patentees are C.A.V., Ltd., and W. E. Nicolls, both of Warple Way, London, W.3. To retain-the convenience of electric starting, however, the smaller engine can be started in this way.

In the drawing, the petrol engine drives the sun-wheel (1) of an epicyclic gear, the planet-carrier of which drives the main starting gear through a freewheel (2). The free outer annulus of the epicyclic gear has external teeth which mesh with the pinion of an electric motor (3), the direction of which is reversible.

In operation, the motor is energized and turns the small engine via the ammlus and sun-wheel, the planetcarrier being held by its free-wheel. When the small engine is running, the electric motor is reversed; this drives the annulus in the same direction as the engine is driving the sun-wheel, so that their united power is applied to the planet-carrier and passed on to the main engine. When the engine is still hot, the electric motor alone may be sufficient for a re-start; this operation can be performed by running it in the " reverse " direction, in which case the small engine is held against rotation by a gecond free-wheel (4).

AN UNORTHODOX TYPE OF ENGINE

AN engine employing self-ignition by means of a flame propagated from an adjoining cylinder is shown in patent No. 567,922 by M, G. Knight, Claremont, Tasmania, Australia. This inventor claims that such an engine can be run on liquid fuel or dust fuel, in particular, on sugar-dust. A group of four cylinders is the minimum unit, and the cylinders are arranged at the four corners of a square; two of them • are the usual way up, the other two being upside-down. This calls for two crankshafts, one above and one below the cylinders; they are placed with their axes at right-angles to each other.

The drawing shows two cylinders in consecutive firing order; the piston (1) is a.. its outer dead centre (end of firing stroke), but the exhaust valve (2) has not yet opened. The adjacent cylinder (3) is at maximum compres

sion, ready for firing. At a timed moment, a transfer valve (4) is opened, whichlets flame from the fired cylinder pass through a slot (5) in the wall and ignite the compressed charge. The transfer valve is made to close under high pressure, so that there is no possibility of a blow-back. A hand

set piston-valve (6) controls the effective length of the transfer slot and so acts as an advance-retard adjustment.

Sparking plugs are provided, but 'these are used only for starting, for which purpose petrol is used. Other designs show sleeve valve3 to control the flame transfer, and an adjustable piston-like head fo each cylinder to provide a variable compression.

AN OVERLOAD CLUTCH

THE problem of making a perfect automatic gearbox would be greatly simplified by a dutch that would drive up to a certain torque and then release

itself to let the next gear train take up the drive. A clutch claimed to be of use in this direction forms the subject of patent No. 567,676, from 0. Wolff, Chestnut Hill, Mass., U.S.A.

The specification contains 29 drawings illustrating various embodiments of the invention, all of which operate on the same basic principle. The accompanying drawing illustrates this, and shows the clutch in the engaged and slipping positions respectively. The driving plate (I) is spring-loaded into contact with the driven plate (2), via a series of interposed rocking shoes (3). Theparts are immersed in• oil, but the working pressure is sufficient to squeeze out the film and create a metal-to-metal contact which transmits the drive; this position is shown in the right-hand .drawing. Should the maximum driving torque be exceeded, however, the first few degrees of slip causes the shoes to rock slightly and SO set up a "14lichell" effect, which permits free slippage; this is shown on the left.

Driving contact is restored by synchronizing the plate speeds,

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Locations: Claremont, London

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