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A Novel Injection Pump

30th August 1957, Page 60
30th August 1957
Page 60
Page 60, 30th August 1957 — A Novel Injection Pump
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Which of the following most accurately describes the problem?

TO measure accurately a few cubic millimetres of fuel and injeetiit at a high pressure is a duty calling for precise yet robust construction. This is what makes the conventional injection pump such an expensive unit. A new approach to the problem is shown in patent No. 778,962, the abject being mainly to reduce the cost: (R. Stevens, " Dunoon," 30 Coombe Lane, Kingston, Surrey.) If a piece of certainmetals (iron or nickel for example) be magnetized, it will change 'its length slightly.. This phenomenon, known as magneto-striction, will give a hikh-:speed, movement over a few microns and will exert quite high pressure. Use is made of this property to operate the proposed pump.

The drawing shows the general construction. A rigid framework contains the magneto-strictive element (1) which bears at the top against a diaphragm (2), whilst a bobbin (3) houses thd exciting winding. The space between the diaphragm and the top plate forms the pump chamber. No valves arc needed, because the diaphragm is provided with a seating ring (4) which opens on the downstroke but closes first on the upstroke, trapping fuel in the centre portion.

The vertical depth of the pump space is microscopic and is produced by etching. Quantitative regulation is given by varying the strength of the current to the winding. One pump per engine cylinder would be used and they would be operated in timed sequence by

electric contacts. , The patent covers also the use of a piezo-electric crystal instead of a magneto-strictive unit. This is a crystal that alters its length when a changing potential is applied to it.

A LIQUID-COOLED BRAKE PATENT No. 778,557 shows a brake layout in which each wheel assembly is provided with a liquid cooling system. (General Motors Corp., Detroit, Michigan, U.S.A.) The liquid is piped to the vehicle radiator where it passes through a heatexchanger and returns. A novel feature is that each wheel has a built-in pump to circulate the fluid. Normally the pumps are stationary, but when the

A34 brakes are applied a clutch is engaged to set them in motion. This means that the rate of liquid circulation is proportional to road speed.

• The drawing shows the construction of the pump used in the hubassembly.

It is of the eccentric-vane type and rotates in a housing attached to the backplate. Liquid is drawn through a wedge-shaped inlet (1), and discharged through a series of exit holes (2). The rotor (3) is driven from the axle via the friction clutch mentioned above.

The actual brake is of the multi-plate type and the cooling liquid is passed through grooves cut in the back face of the friction discs, Because of this,. the heat is absorbed by the liquid virtually at the point of generation.

VEHICLE FOR HOT LOADS TAR wagons and other vehicles carry' ing loads which must be kept liquid by heat are usually provided with an exhaust-operated warming system for use while running, but when a vehicle has to stand all night, this becomes inoperative.

Patent No. 777,265 shows such a vehicle in which electric heating is additionally provided for use in these circumstances. (H. Lawrence, 2 Little Park, Wickham, Hants.) DAMPING TORSIONAL VIBRATIONS

E.VEN a multi-cylindered engine having a heavy flywheel can create quite high torsional stresses due to alternating cyclic accelerations and decelerations, and these can impose severe transient loads on the transmission, A coupling claimed to eliminate these vibrations forms the subject of Patent No. 778,995. (S. Smith and Sons (England), Ltd, Cricklewood Works, London, N.W.2.)

The proposed unit makes use of a magnetic-powder coupling in series with a mechanically resilient member. The engine shaft (1) _carries a flange (2) in which is enclosed a circular array of permanent magnets. In a close-fitting air-gap is a narrow cylindrical sleeve (3) carried on a thin ,spring disc (4); this forms the output member.

'The., air-gap is filled with magnetic powder which is compacted by the flux from the magnets and forms an active damping device to the oscillations of the springy disc. A ball-centring bush (5) permits slight axial 'deflections to occur.

• ALLOY VALVE-SEATINSERTS

A'alloy for producing valve-seat inserts by casting forms the subject Of patent No 779,544. In addition to iron the alloycontains 40 per cent. nickel, 20 per cent. chromium, 12 per cent. cobalt. and six per cent. tungsten

molybdenum. , It is stated that the material has a good resistance to 'lead compounds at high temperatures, and to collapse. (Thompson Products, ink., Cleveland 17, Ohio, U.S.A.) FITTING TUBELESS TYRES

BEFORE a tubeless tyre can be inflated, it must first make a seal along the rim and this is sometimes a matter of difficulty when a new tyre is being. fitted. Once inflated, the tyre is firmly held by its own pressure. A tool to facilitate the fitting of -these tyres is shown in patent No. 779,328. (United , States Rubber Company, Rockefeller. Center, 1230 Avenue of the Americas. New York, U.S.A.) If the cover be forced radially, inwards, it can be made to effect a temporary seal which will hold until inflation takes over. The patent shows a simple means for doing this. Around the cover is placed a flat tube (I) made of rubbered fabric. If this be inflated, it exerts an inwards force..on the.tja-e and clamps it on to the rim■Riiile inflation proceeds. When the tyre is fully inflated, the outer band can be removed

by releasing its air. .


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