Construction of Automobile Engine and Working Principle

Construction of Automobile Engine and Working Principle

● Before we discuss “Construction of Automobile Engine and Working Principle” we know about what is an Automobile Engine?

→ Any machine which converts heat energy into mechanical energy is called an Automobile Engine.

● How many types of Automobile Engines?

There are various types of engines used in automobiles:-

(1) External combustion engine.

In external combustion engines are those engines where fuel is burnt outside the combustion chamber such as steam engines and turbines.

(2) Internal combustion engine

Internal combustion engines are those engines where fuel is burnt inside the combustion chamber such as petrol, diesel engine, and wankle engine.

● How many parts are attached to the Construction of an Automobile Engine

→ Cylinder and Piston

Construction of Automobile Engine and Working principle

Cutaway of a simple single cylinder petrol engine the upper and is closed by the cover cylinder head but the lower and is open in the form of a hollow tube in which piston moves.

The piston is a hollow metal tube with a top and closes it has a close sliding fit or in other words, the piston can slide easily up and down in the cylinder.

→ Connecting rod and crankshaft

Construction of Automobile Engine crankshaft and connecting rod

The up and down movement of the piston in the cylinder is called reciprocating motion.

This reciprocating motion must be changed into rotary motion so that the wheels of the automobiles could be made to rotate.

This change of reciprocating motion to rotary motion is accomplished by a crank on the crankshaft with help of connecting rod, with connect the piston with help of a pin gudgeon pin at its upper part while its lower part is fast and to the crankpin of the crankshaft.

As such when the piston moves up and down in the cylinder the upper end of the connecting rod moves up and down with it.

The lower end of the connecting rod also moves with it up and down since it is attached to the crankpin of the crankshaft the crankpin moves in a circle with the result crankshaft gets rotary motion.

Each moment of the Piston from top to bottom or from bottom to top is called a stroke.

The Piston moves 2 strokes as the crankshaft moves one complete revolution.

→ Valves

construction of automobile engine and working principle

There are valves at the top of the cylinder a valve is an accurate machine plug that fits in the machine opening at the top of the cylinder.

When the valve is resting on its seat (opening), it is said to be closed and when it is lifted up or pushed off its seat it is opened.

One of the valves is called the inlet valve which allows a mixture of fuel and air into the cylinder.

The Other valve is called the exhaust valve which allows burnt exhaust gases to escape or get out of the cylinder.

engine  Valves opening and closing diagram

Valves opening and closing is so arranged and time that this open and close at the required time.

● Cut view of Automobile Engine and Working Principle

Construction of Automobile Engine and Working principle

→ During the downward stroke of the piston when the inlet valve opens the air-fuel mixture is drawn in due to a partial vacuum created in the cylinder.

This is somewhat the same effect as when you drink liquid with help of a straw, in this case, a partial vacuum is created in this mouth and the liquid moves up through the straw to the mouth.

The mixture of fuel and air in correct proportion is done by the carburetor when the piston reaches the bottom dead center inlet valve closes thus seals the upper end of the engine.

Construction of Automobile Engine and Working principle

Here we would like to add a little bit amount burning of fuel it is the oxygen in the air which combines with the fuel of combustion.

The important thing to note is to see how fast we can burn the fuel so that it can exert full force on the piston to get full power from the engine.

The burning fuel rapidly we have to choice vaporize fuel just to explain you this phenomenon so that you understand the subject more clearly if you Burnt fuel is a container it burns lazily.

Construction of Automobile Engine and Working principle

This is because the engine in the air contacts the surface of fuel on top only but this is not required.

We required a short of explosive burning of fuel to get full power asset earlier however to power full explosion is also not required as it will destroy the engine.

Now to burn the fuel completely and quickly we cannot heat fuel but instead, the air in the compression stroke as well as vaporize fuel through carburetor in petrol engine and diesel engine through the injector.

As the crankshaft continues to rotate it pushes up the Piston in the cylinder thus compressor the combustible mixture in the cylinder is called compression stroke.

Construction of Automobile Engine and Working principle

At the end of the compression stroke, compressed gases are ignited with help of a spark plug.

At the end of the compression stroke, compressed gases are ignited with help of a spark plug this electric Spark set to the compressed air-fuel mixture.

The mixture burns so rapidly that it might be said to explode when the mixture burns the temperature and pressure or gases increases rapidly.

Since the piston is the only moving part in the cylinder the high pressure produced by gases forces the piston down

Construction of Automobile Engine and Working principle

As the piston is tied to the crankshaft with help of connecting the rod crankshaft rotates this is called power stroke.

At the end of the power stroke exhaust valve opens the burnt gases which have done their work by pushing the Piston downward must be cleared from the cylinder.

In the 4th stroke in exhaust stroke when Piston moves up it pushes the burnt gases out of the cylinder through the open exhaust valve.

The valve closes at the end of the exhaust stroke and again the inlet valve opens and the fresh charge was taken in it it is how the whole cycle is repeated which makes the engine run.

We hope readers can understand this Construction of Automobile Engine and Working Principle” article and basic fundamentals of an automotive engine.

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FAQ

Which energy is used from a running engine?

Thermal efficiency

What is the diameter of cylinder?

Bore

The distance traveled by piston from upside to downside or from downside to upside one time is known as :

Stroke

power stroke is acquired by the rotation of crank shaft on :

180°

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