Avoiding Close Tolerances
Page 66
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DATENT No. 834,710 shows an injec tion pump in Which close tolerances arc not required between the plunger and barrel. It is designed to reduce manufacturing cost. (The S.U. Carburetter Co., Ltd., Wood Lane, Erdington, Birmingham, 24.) The drawing shows sufficient of the proposed pump to illustrate the sealing. principle. Two separate plungers are used, a small one (1) and a-larger one (2) which receives the thrust of the cam (3).
On the downstroke of the plungers a vacuum is created in the pumping space (4) and in an annular space (5). As soon as the plungers reach the region supplied by the feed-pump (6) both spaces fill with fuel.
On the upstroke, the lower plunger pushes the upper one by mechanical contact at first. As soon as the spill ports are closed, the upper plunger is hydraulically propelled and tends to move ahead of the lower one , because .of the difference in their diameters. This action opens a spill clearance (7) so that the actual effect is to maintain a constant pressure in the lower space which is slightly greater than the injection pressure on the top plunger.
Fuel leakage cannot occur for the simple reason that the pressure under the plunger is higher than that above it. Leakage from the lower fuel belt does not matter because it is unrnetered. The patent describes also a quantity control device and a rotary distributor. These are separate units, but they employ the same principle to prevent leakage.
ELECTRIC INJECTION
AFUEL injector that is opened and shut electrically is shown in patent No. 834,950. The injector is simply an on-off valve fed with fuel under pressure. (Robert Bosch G.m.b.H.. 4 Breitscheidstrasse, Stuttgart-W, Germany.)
The drawing shows the circuit employed and a diagrammatic view of the injector (1). The spring-closed needle-valve opens when a solenoid (2) is energized. An engine-driven cam (3) controls the commencement of injection. This occurs when the cam closes the contacts and triggers off, via a relay, the transistor (4) which passes the solenoid current.
Duration of injection is7 determined by. electrical means. When the contacts are closed, they also charge a capacitor (5) which maintains the control current after the contacts have re-opened. Thus, the timing is dependent on the charge in the capacitor, and thi can be adjusted by a variable leak resistor (6).
The unit shown at 7 is optional and consists of a parallel resistor (8) which is switched in and out by another enginedriven cam (9). This acts as a governor, reducing the fuel_ supply as the engine speed rises.
CENTRIFUGAL AIR CLEANER. A CENTRIFUGAL intake air cleaner 1—Iis shown in patent No. 834,715. The unit described is robust and requires little servicing. (Vokes, Ltd., Henley Road, Guildford, Surrey.)
The drawing shows a section of the cleaner, which has a diameter of 1 ft. 2 in. and is 2 ft. long. Air enters through a number of wire-mesh covered apertures (1) and passes to the left to reach the annular spaces (2) between large and small concentric tubes. Each space contains a helically vaned cyclone (3) which • spins the air and causes the dust to be thrown outwards.
The dust collects in the hopper (4) while the clean air passes back through the inner tubes to reach a space (5). This is joined to the pipe (6) which leads to the induction .manifold. The 'dust hopper is quickly detachable.
SELF-LOADING JIB
pATENT No. 835,033 refers to vehicles fitted with bolsters above the cab to carry long loads such as poles and bars of Metal. The subject of the patent is a jib for unloading such goods
when no crane is available. (C. G.
Chantrill and Partners, Ltd., National House, Moorgat e, London, E.C.2, Gardiner, Sons and (o., Ltd., Nelson Street, Bristol, and V. Bullock.)
The drawing shows one side o17. the tubular bolster (1) which is located in a pair of cups (2) on the floor of the body. The bar is rein
forced by braces (3) and transverse bracing. .
The invention consists of a jib (4), the. stem of which swivels inside the bore of the tube. A block and tackle can be attached to the hook (5) or a single pulley can be used in conjunction with a winch on the vehicle. When not in use, the jib is lifted out of the tube and a rubber plug is inserted.
.GAS TURBINE BRAKING THE aim of patent No. 835,090 is to enable a road vehicle powered by a gas turbine to obtain braking effect from the power unit. (Daimler-Benz A.G., Stuttgart-Unterturkheim, Germany.) The drawing shows‘ the general layout of a. gas turbine suitable for such an application. A compressor (1) feeds air to the multiple combustion chambers (2). The combustion products drive a turbine (3) which is connected to the compressor, and then pass to the main power turbine (4) whence they exhaust to atmosphere. A one-way clutch (5) permits the compressor to overrun the power turbine, and a gearbox (6) leads to the trans. mission system.
When braking is required, the pedal movement cuts off the fuel supply and then opens a port to atmosphere (7). When this is done, the speed of the compressor and its turbine drops rapidly until the one-way clutch comes into action, after which the road wheels drive both turbines and the compressor to absorb energy, PLASTICS BEARING CAGES
PATENT No. 833,847 comes from A.B. Svenska Kullafabriken, Gothenburg, Sweden, and describes a ball-bearing cage that can be moulded in plastics material. To prevent distortion by centrifugal force, a channel-section steel reinforcement is incorporated.