Fuel Nozzles for Oil Engines
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TN addition to its well-known range of j_fuel pumps for compression-ignition engines, Bents, Ltd., 24, Holborn, London, E.C.1, is now marketing injector nozzles for such power units. On this page we reproduce a sectional view to show the working principles. Fuel , enters the body of the injector through a horizontally disposed pipe and then passes downwards to an annular chamber which is in connection with the hole bored axially through the body. Ai the needle is fluted, oil can pass freely down into a second chamber below a shoulder on the needle. The flutes are so proportioned that the area of the passage around the needle is equal to the area of the circular passage through which the fuel travels to reach the annular chamber.
When pressure is built up to the required degree, the needle is forced off its seating against the pressure of the
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compression spring situated at the top. Fuel then passes through a single aperture into the combustion chamber. This hole is .5 mm. in diameter, and the opening in the end of nozzle is countersunk at an angle of 60 degrees. Surplus oil is taken away by an overflew pipe.
It is important to note that removal of the injector block does not interfere with the setting for the needle, as, of course, the needle and its controlling spring are contained in the same portion of the device. Adjustment can be effected while the engine is running.
With a fuel nozzle of this type there is far less risk of choking, due to the presence of burnt oil, than in the case of an open nozzle, whilst the needle prevents the tendency to dribble.
These injectors are made in various sizes to suit engines of different design; for example, a body with a reach of 40 mm. or 70 mm. can be obtaiited.