Diesel Pump and Diesel Engines.

Published: 28th April 2010
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Diesel pump or as it is frequently known an injection pump typically is used to fuel a diesel engine, injection pumps can be used to supply fuel to a petrol motor also.

A diesel pump, in the early engines, would have been powered by the engine using a connection directly to the engines crankshaft. The diesel pump will be timed to inject the diesel into the engine at the right time during the pistons stroke.

Normally a diesel engine in your regular car, van or lorry will be of the four stroke variety, superior engines used in ships and large machinery will often be of the two-stroke variety to augment fuel proficiency. Two-stroke engines you would usually find in a moped or lawnmower, of course these use gasoline to run.

The main difference with a two-stroke engine is that the initial and ultimate strokes are carried out simultaneously, this has the consequence of drastically increasing efficiency at the expense of a dirtier exhaust. Another advantage is that two-stroke engines can be easily run in reverse, providing a reverse function without the requirement for complex gearing mechanisms.

In the modern motor there are two main sorts of diesel engine, those are the common rail diesel engine and the electronic unit direct injection.

An electronic unit direct injection assembly combines the injector and diesel pump into a singe part, the diesel pump is, normally, still driven by the engine. An Overhead Camshaft (OHC) drives the diesel pumps and injectors, this is an assemblage sat on top of the engine and linked directly to the engines main cam shaft by chain, or more commonly nowadays, a belt.

The common rail diesel engine consist of a high pressured fuel rail, essentially a manifold, supplying separate diesel fuel injectors as opposed to the diesel pump delivering fuel directly to the fuel injectors.

As stated, above, your modern diesel engine works on a four stroke cycle. You possibly will have heard this referred to as the Otto cycle after the inventor of the petrol motor, Nikolaus August Otto in 1876. A few years soon after Rudolf Diesel arrived and, wanting to invent a more fuel efficient engine, came up with the diesel engine in 1892.

Diesel engines have been a bit slow on the up-take, for the regular everyday car, largely sue to their repute of being loud and smelly. Evidently this is altering as innovative technology makes the diesel engine a more acceptable answer to our present transportation woes.

The four single events or strokes in a usual four stroke diesel engine are as follows:

The Intake Stroke: As the piston reaches the top of it's stroke and begins to travel downward the air intake valve is opened, this has the result of air being drawn in as the piston travels downward.

The Compression Stroke: As the piston hits the bottom of it's stroke the air intake valve will close, as the outlet valve is also closed the air contained in the piston chamber is compressed as the piston travels back up the shaft.

The Combustion Stroke: As the piston reaches the peak of the compression stroke diesel is injected at the specific moment by the diesel pump and as the piston is fractionally over the top of the upward point of the compression stroke the diesel to compressed air mixture is ignited. This is where the power to drive the vehicle is generated, the piston is forced downward driving the motor.

The Exhaust Stroke: For the duration of the pistons last upward stroke the exhaust valve is opened and the gases produced from the ignition of the air to fuel mixture is expelled out and into the exhaust mechanism. At the end of this stroke the four strokes are concluded and the whole sequence starts again from the start.

One draw back to diesel fuel versus petrol is when used in very wintry climates. Diesel will start to freeze at a higher temperature than gasoline, this will begin by the diesel becoming thicker and waxy, clearly this will inhibit the good running of most diesel engine. One technique is to put a small amount of gasoline into the diesel fuel mixture to help lower the freezing point of the overall mixture.

This furthermore has the extra advantage of making the overall combination more explosive, however too great a mixture can damage a diesel motor, even small amounts of petrol in a common rail engine can trigger critical problems so check with an experienced mechanic prior to changing your fuel mixture.

Another issue that can be effortlessly spotted is if your diesel pump is malfunctioning, this has the outcome of reduced fuel supply or pressure to the fuel system. Basic symptoms are a failure of the engine to start, a lumpy or noisy ignition, or a high pitched whining coming from the engine. You will probably also observe a lack of efficiency when applying the throttle.

If any of these scenarios occur it would be advisable to get your automobile checked out by a mechanic who may need to source you a new diesel pump.


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