Basic Mecanical Ic Engines

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Internal Combustion Engine



Engine

A device which produces power



Introduction

Combustion

A process to convert chemical energy

contained in the fuel into thermal energyEngine

A device which produces power

Heat Engine

A device which produces power from heat

energy which is produced from chemical energy



Classifications of Heat Engines

External Combustion (EC) Engine

The combustion takes place at out side the

cylinder.Eg: Steam engines

External Combustion (IC) Engine

The combustion takes place at inside the

cylinder.

Eg: petrol engines, Diesel engines



Classifications of IC Engines

Based on cycle of operations:

Two Stroke Cycle Engine

Four Stroke Cycle Engine

Based on cycle of combustion:

Otto Cycle

Diesel Cycle

Dual CycleBased on Number of cylinders:

Single cylinder engines

Multi cylinder engines



Classifications of IC Engines cont…

Based on arrangement of cylinders:

Horizontal Engine

Vertical Engine

V- type Engine

Radial type Engine

Based on fuel used:

Diesel Engine Petrol Engine

Gas engine




Based on speed:

Low speed Engines

Medium speed Engine

High speed Engine

Based on Method of ignitions:

Spark Ignition Engines

Compression Ignition EnginesBased on Method of Cooling:

Air Cooled Engines

Water Cooled Engines



Parts of IC Engines

Parts common to both Petrol and Diesel engine:

1. cylinder 2. Cylinder head

3. Piston 4. Piston rings

5. Gudgeon pin 6. Connecting rod7. crankshaft 8. Crank

9. Engine bearing 10. Crank case

11. Flywheel 12. Governor

13. Valves and valve operating mechanism.



Parts of IC Engines cont…

Parts for Petrol engines only:

1. Spark plugs

2. Carburetor

3. Fuel pump

Parts for Diesel engines only:

1. Fuel pump

2. Injector




Cylinder:

where the piston moves up and down.

Hard grade cast iron.

Cylinder Head:

It placed at top of the cylinder to cover the

oneside of the cylinder.

Piston:

cylindrical piece of metal that moves up and

down the cylinder.




Piston rings:

It rounds the piston.

Cast iron.

Their main function is to provide a good sealing

fit between the piston and cylinder .

prevent fuel/air from leaking into the sump

prevent oil from entering the combustionchamber




Combustion chamber:

Area where combustion and compression takes

place.

Connecting rod: It transmits the piston load to the crank to

convert the reciprocating motion of the piston

into rotary motion of the crankshaft.

Gudgeon pin

It supports and allows the connecting rod to

swivel.




Crankshaft:

It converts the reciprocating motion of the

piston into the rotary motion

Spark plug:

supplies spark for the fuel/air mixture.

Inlet Valves:

Admits the air or mixture of air and fuel intoengine cylinder.




Outlet Valves

Discharge the product of combustion.

Flywheel

In engine it takes care of fluctuations of speed

during thermodynamic cycle.



Terms connected with IC Engine

Bore:

Diameter of the cylinder or diameter of the

piston face

Top Dead Center (TDC):

The Maximum position of the piston inside the

cylinder

Bottom Dead Center (BDC): The Minimum position of the piston inside the

cylinder



Terms connected with IC Engine cont…

Clearance volume:

Minimum volume in the combustion chamber

with piston at TDC.

Stroke:

Amount of vertical travel of the piston from bottom dead

center (BDC) to top dead center (TDC)



Terms connected with IC Engine cont…



Four Strokes of an Engines

The four strokes are:

1. Suction Stroke

2. Compression Stroke

3. Power Stroke

4. Exhaust Stroke



Working of Four Stroke Diesel Engine

Suction Stroke:

Piston moves from TDC to BDC.

The inlet valve is opened.

The exhaust valve is remained closed for

entire stroke.

Vacuum is created inside the cylinder, so air is

entered into the cylinder. Where volume is increased and pressure is

reduced.

Flywheel completes half revolution.




Suction Stroke




Compression Stroke:

Piston moves from BDC to TDC.

The inlet and exhaust valves are kept in

closed condition.

Now the air is compressed inside the cylinder

to high pressure and temperature.

At end of the compression stroke the fuel isinjected by fuel injector. The fuel is atomised.

Flywheel completes one revolution.




Compression Stroke




Power Stroke:

Piston moves from TDC to BDC.

The inlet and exhaust valves are kept in

closed condition.

Fuel is burnt by the high temperature of air

and makes a downward thrust.

The high power is transmitted to crankshaftthrough connecting rod.

Flywheel completes one and half revolution.




Power Stroke




Exhaust Stroke:

Piston moves from BDC to TDC.

The inlet is kept in closed condition and

exhaust valves is in opened condition.

The burnt gas is allowed to go out of the

cylinder due to upward movement of the

piston. Flywheel completes two revolution.




Exhaust Stroke



Working of Four Stroke Petrol Engine

The four strokes are:

1. Suction Stroke

2. Compression Stroke

3. Power Stroke

4. Exhaust Stroke




The working principle is similar that of Dieselengine.

Replace the words

Air by air fuel mixture &Fuel injector by spark plug



Working of Two Stroke Petrol Engine

Suction Stroke:

Inlet port is in opened condition.

Transfer and Exhaust Ports are in closed

condition.

Piston moves from BDC to TDC

The fuel/air mixture is drawn into the

crankcase by the vacuum created during theupward stroke of the piston.




Suction




Compression Stroke:

Inlet port is in opened condition.


condition. Piston moves from BDC to TDC

The piston compresses fuel/air mixture which

is at top of the piston. At the same time , another intake stroke is

happening beneath the piston

The crank completes half revolution of rotation.




Compression




Power Stroke:

Inlet port is also in closed condition.


condition.

Piston moves from TDC to BDC

At the top of the stroke the spark plug ignites

the fuel mixture. The burning fuel expands, driving the piston

downward




Power




Exhaust Stroke:

Inlet port is in closed condition.

Transfer and Exhaust Ports are in opened

condition.

Piston moves from TDC to BDC

the compressed fuel/air mixture in the

crankcase is allowed to enter into the maincylinder through transfer port.

This freshly entered air fuel mixture expels

the exhaust gasses out the exhaust port,




Exhaust

Basic Mecanical Ic Engines

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