Machine which converts Chemical energy of fuel into Mechanical rotary energy is called Internal Combustion Engine. It is termed as Internal Combustion because it produces power by using the combustion power of fuel. It is termed as Internal because Combustion takes place in closed chamber.

Before going deep into working, it is important to have look on basic parts of IC Engine. Because without knowledge of parts proper knowledge of working is difficult to learn.

Parts of Internal Combustion Engine

1. Exhaust Cam Shaft

The main function of Exhaust Cam shaft is to actuate Exhaust valve so that exhaust gases can be expelled out of combustion chamber and when Exhaust Cam shaft rotates and the Lobe on Cam pushes down the Exhaust Valve.

2. Inlet Cam Shaft

Function of inlet cam is to actuate Inlet Valve and the cam shaft is identical to the exhaust cam shaft.

So Cam shafts are in connection with crank shaft and rotate at half the speed of crank shaft.

3. Valve Caps

The function of valve cap is to reduce wear and tear of valve tail tip because of contact with valve actuation mecahanism. It is known as valve cap because it is installed on valve tail.

4. Internal Combustion Engine Spark Plug

It’s function is to ignite the Air-Fuel mixture. Spark is produced and it ignites compressed Air Fuel Mixture.

5. Internal Combustion Engine Inlet Valves

lets the air and fuel to enter into combustion chamber during suction stroke. Generally the inlet valve has larger area than the Exhaust valve so that more air and fuel can enter the engine cylinder.

6. Internal Combustion Engine Exhaust Valve

Let the exhaust gases produced because of explosion to expel out the combustion gases from combustion chamber. Exhaust cam actuates the exhaust valve.

7. Internal Combustion Engine Head

This is covering on the combustion chamber that contains valves, valve actuation mechanisms, cam shafts, spark plug etc.

8. Piston and Piston rings

Piston reciprocates (moves up and down) to create vacuum during the suction stroke and compressing the air fuel mixture during the compression stroke. Rings fitted into grooves in periphery of piston because they are used to prevent leakage from the combustion chamber and these rings are known as piston rings.

9. Gudgeon Pin

It is machine element used to connect piston and connecting rod. Gudgeon pin also known as Wrist pin and is installed into piston.

10. Connecting Rod

It is used to connect the crank shaft and piston so, the motion of piston is transferred to crank shaft using connecting rod and vice versa.

11. Crank Case

It is basically the outer body which holds all the elements like crankshaft.

12. Crank Shaft

It is used to convert the reciprocating motion of piston into rotary motion. The crank shaft is also output for engine power.

So now you may have heard the phrase 4 Stroke engine and 2 Stroke engine. Now days most of vehicles are equipped with 4Stroke Engine because of high efficiency and low emissions compared to 2stroke engines.

4 Stroke engines are presently in use in Automobiles. But 2 Stroke engines are very rarely used because of low efficiency, high fuel consumption and high emissions. But 2 stroke engines are used in some special applications like small lawn movers and small pocket bikes.

Working Principle of Internal Combustion Engine

4 Stoke Engine basically work in 4 stages known as strokes. Thus one stroke means piston has completed one travel between its extreme positions namely TDC (Top Dead Center) and BDC (Bottom Dead Center). TDC is top most possible position of piston while BDC is lowest possible position of piston.

Suction Stroke

Suction of air and fuel takes place so it is known as Suction Stroke. Piston moves from top most position (Top Dead Center or TDC) to the lowest and inlet valve open, so it creates vacuum. This results Air and Fuel to flow inside cylinder through inlet valve because of vacuum produced during suction. Only inlet valve remains open during suction stroke and exhaust valve remains in closed position.

Compression Stroke

Because compression of air fuel mixture takes place in this Stroke,so it is named as compression stroke. So after the suction stroke the compression stroke takes place. And during compression stroke the Piston moves from its lowest position (Bottom Dead Center or BDC) to TDC. Both the valves are close during compression.

Power Stroke

It is known as power stroke because power is generated from combustion in this stroke. When Piston approaches near to TDC in Compression stroke the spark plug ignites ignites spark and because of spark compressed air fuel mixture explodes. Thus Piston pushes towards the BDC because of high amount of pressure rise inside combustion chamber.

During power stroke both valves are in closed position so that no pressure leakage takes place.

Exhaust Stroke

It is known as Exhaust Stroke as the exhaust gases are thrown out. Thus in exhaust stroke the piston moves from BDC to TDC. So the exhaust valve remain open to expel out the residual gases produced during combustion.

After the Exhaust stroke the suction stroke takes place and process continues.

So, as we have studied that out of 4 strokes, only one stroke is giving out power, power stroke. So question here arises is, How rest of process takes place because power is delivered only in power stroke?

So, the answer is Flywheel or Harmonic Balancer. Because Rotational energy is store in Flywheel. This Rotational Energy provides power in rest on 3 strokes because only power stroke out of 4 strokes provide power output. So Rest of three strokes take place under the action of rotational energy stored in flywheel. Also with the use of flywheel the power output of engine is linear, because it balances the pulses in power output.

For history of IC Engine click Here

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