000-209 Intro to CS. 5/Mother 1

Element of Mechanical Engineering

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Internal combustion engine

I.C Engines

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Introduction

An internal combustion engine is a heat engine which converts the

heat energy released by combustion of fuel taking place

inside the engine into mechanical work.

Heat energy

Mechanical work

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Classification

According to type of fuel used.Petrol engine.Diesel engine.Gas engine.Bi-fuel engine.

According to number of strokes per cycle.

4 – stroke engines.2 – stroke engines.

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Classification

According to method of ignition.Spark ignition. Compression ignition.

According to the cycle of combustion.

Otto cycle.Diesel cycle. Duel combustion.

According to the number of cylinders.

Single cylinder.Multi cylinder.

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Classification

According to the arrangement of cylindersVertical engine.Horizontal.Inline engine.Radial engine.V- engine.

According to method of coolingAir cooled engine.Water cooled engine.

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Position of the cylinder

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Parts of I.C Engine

CylinderPiston

Piston ringsConnecting rod

Crank and crankshaft

ValvesFlywheel

Crankcase

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1.Cylinder

It is the heart of the engine in which the fuel is

burnt and the power is developed.

The inside diameter are called “bore”.

The piston reciprocates inside the cylinder

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Cylinder

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2.Piston

Close fitting hollow – cylinder moving to and fro in the cylinder.

Function – power developed by the combustion of fuel is transmitted by piston to the crank-shaft through the connecting rod.

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Piston

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3. Piston rings

Metallic rings inserted into groves provided at top end of the piston.Function – it maintains a gas-tight joint between the piston and the cylinder.

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Piston Rings

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4. Connecting rod

Link that connects the piston and crankshaft by means of pin joint.Function – it converts the rectilinear motion of the piston into rotary motion of crankshaft.

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Connecting road

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5.Crank and crankshaft

Crank is a lever that is connects crankshaft and connecting rod.Crankshaft is a shaft which transmits power from engine to wheels.

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Crank and crankshaft

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6.Valves

These are devices which control the flow of intake and exhaust gases.

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Valves

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7.Fly wheel

Mounted on crankshaft to maintain uniform rotation of crankshaft.Restores the energy to the piston.

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Fly-wheel

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Four stroke petrol engine

Four stroke petrol engine consists of

CylinderCoverMechanically operated valvesSpark plugConnecting rod and crank

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Construction and working ofFour stroke PETROL engine

1.Suction stroke

2.Compression stroke

3.Power stroke

4.Exhaust stroke

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1.Suction stroke

Inlet is open exhaust is closed.

Piston moves from TDC to BDC.

Crankshaft revolves half the rotation.

Cranking Petrol air mixture drawn

into cylinder due to pressure difference.

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2.Compression strokeBoth inlet and exhaust are

closed.Piston moves from BDC to

TDC.Crankshaft revolves half the

rotation.Cranking

Petrol air mixture is compressed to a ratio of

1:11.This mixture is ignited by

spark plug.

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3.Power stroke

Piston moves from TDC to BDC.

Crankshaft revolves half the rotation.

burnt gases generate energy and force the piston to move down.

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4.Exhaust stroke exhaust is open and inlet

is closed.Piston moves from BDC to

TDC.crankshaft revolves half

the rotation.energy for this stroke is supplied by flywheel.

Burnt gases are expelled out through outlet port.

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Four stroke petrol engine

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Construction and working ofFour stroke DIESEL engine

1.Suction stroke

2.Compression stroke

3.Power or expansion stroke

4.Exhaust stroke31

1.Suction stroke

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Inlet is open exhaust is closed.Piston moves from TDC to BDC

and crankshaft revolves half the revolution.

Cranking during first cycle.Due to the pressure difference air enters the cylinder through

air filter.

2.Compression stroke

Inlet and exhaust are closed.Piston moves from BDC to

TDC.Cranking required in first

cycle.Air will be compressed to a

ratio of 1:20.Diesel oil is sprayed into cylinder by injector and

auto-ignition takes place.

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3.Power stroke

Piston moves from TDC to BDC.

Inlet and exhaust valves are closed.

burnt gases generate energy and force the piston to move down till injection of fuel is

complete.

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3.Exhaust stroke

exhaust is open and inlet is closed.

Piston moves from BDC to TDC.

crankshaft revolves half the rotation.

energy for this stroke is supplied by flywheel.

Burnt gases are expelled out through outlet port.

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Four stroke diesel engine

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Thank youPrepared by:- Manthan R.

KananiEnrollment Number:-

140050119028 Roll no:- 14 ME 028