THE DIESEL ENGINE FUEL SYSTEM

1. The main difference between the petrol engine and the diesel engine is in the method in which the fuel is supplied to the cylinders and ignited.

2. We know the diesel engine to have no carburettor and no electrical equipment to provide a spark for the fuel ignition.

3. The diesel engine fuel system includes an air cleaner, a fuel pump, fuel filters, fuel injection pump and fuel injectors.

4. The air cleaner is the same type of air cleaner as fitted to petrol engines.

5. A fuel lift pump is fitted to the fuel line of the diesel fuel system. Such pumps are necessary on vehicles where the fuel tank is not placed high enough to maintain a good gravity flow. This is always the case with cars but not always with tractors because the fuel tank is placed high enough.

6. One or more fuel filters are sure to filter the fuel as it is pumped from the lift pump to the injection pump. These filters are of the same form as a metal container in which there is some filter element and they are ar­ranged so that the fuel should pass through the element. The dirt being trapped on the surface of the element, it is necessary to replace these elements at recommended inter­vals. The interval varies according to the type of the ele­ment used (usually from 200 to 400 working-hours of the engine).

7. The fuel injection pump is a very important and ex­pensive part of the diesel engine. It is expensive because a lot of skilled work is necessary to make a precision instrument. It is important because it must deliver accu­rately to the engine very small quantities of fuel. In a muticylinder engine the quantities of fuel delivered to each cylinder must be equal and delivered at high pres­sure. Two types of fuel injection pumps are usually em­ployed on farm tractors: a plunger type pump or a distri­butor type pump. In both cases engine speed is increased by the acceleration control which causes the pump me­chanism to deliver an increasing quantity of fuel to the engine.

8. The fuel injector is considered to be another very accurately made part of the diesel fuel system and its pur­pose is to inject into the cylinder the small quanitities of the fuel. The fuel is to be delivered in a very fine spray and this is achieved partly because it is forced through little holes in the end of the injector and partly because the pressure which forces it through these holes is very high.

9. From the tank the fuel passes through the top into a filter bowl then it is delivered by gravity down to the lift pump in which there is another filter. The lift pump pumps the fuel up and through the main fuel filter. From this point the fuel passes to the injection pump which meters it and pumps it through the injector into the cylinder in which compression of air has taken place.

10. It being necessary to increase the speed of the diesel engine, the operator has to open the throttle control which moves a mechanism within the injector pump and more fuel is expected to be delivered to each cylinder.

 

III . Answer the questions.

1. What is the main difference between the petrol engine and the diesel engine in the method in which the fuel is supplied to the cylinders and ignited?

2. Does the diesel engine have a carburettor and an electrical equipment?

3. What does the diesel engine fuel system include?

4. What type of the air cleaner is used in the diesel engines?

5. Why is a fuel lift pump used?

6. Why are the fuel filters used?

7. What is the form of fuel filters?

8. Is the fuel injection pump a cheap part of the diesel engine?

9. How is the fuel delivered to another filter?

10. How does the lift pump pumps the fuel?

11. Is it possible to increase the speed of the diesel engine? How?

IV. Match the antonyms.

outside, irregular, start, after, regular, high, top, reduce, low, slow, bottom, big, stationary, small, finish, moving, inside, draw into, before, increase, rapid, expel.

 

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