Engine construction

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Department of Technical Education
Andhra Pradesh
Branch : Automobile Engineering
Institute : Govt. Polytechnic, Atmakur
Year/Semester : III Semester
Subject : Automobile Power Plants
Subject Code : A302
Topic : Engine Construction
Duration : 50 Minutes
Sub Topic : Classification, Functions & Materials of
Engine Components
Teaching Aids : Images, Animations & Text
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Objectives
On completion of this session, you would be able to
know:
• Functions of Cylinder Block, Cylinder and liners
• Materials used for above components
• Construction details of above components
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• Have you ever traveled by a bus ?
• What the driver first do to move the bus ?
• If your answer is starting the engine ?
• What the engine consists of ?
Introduction
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The actual meaning of prime mover is a primary source of power. It means
all the machinery that provide power for performing different mechanical
work.
Prime Mover: an initial source of motive power (such as a windmill,
waterwheel, turbine, or internal combustion engine) designed to receive and
modify force and motion as supplied by some natural source and apply them
to drive machinery.

6. Types of engines: Mainly engines are of two types.
External Combustion Engines: The External Combustion Engines are those in
which the combustion takes place outside the engine cylinder. E.g.: Steam
Engine.
Internal Combustion Engines: In the Internal Combustion Engines the
combustion of fuel takes place inside the engine cylinder. E.g.: All Automobile
Engines.
Functions of I.C. Engine: Engine is that kind of prime mover which converts
chemical energy of fuel into mechanical energy. The fuel on burning changes
to gas which impinges upon the piston and pushes it to change into
reciprocating motion. The reciprocating motion of piston is then converted to
rotary motion of crank shaft with the help of slider mechanism involving
connecting rod and crank shaft. Dr V Venkateswarlu 6

7. Classifications of I.C. Engines
The I.C. Engine can be classified on the basis of
1.Working cycle:
a. Otto cycle Engine or Spark Ignition Engine (S.I. Engine)
b. Diesel Cycle Engine or Compression Ignition engine (C.I. Engine)
2. Number of strokes:
a. Two Stroke engine, b. Four Stroke engine.
3. Fuel used:
a.Liquefied petrol engines, b. Diesel engines, c. Gasoline or petrol,
b.d. Compressed Natural gas engines, e. Methane or ethanol engines.
4. Fuel supply system:
a. Fuel supply through carburetor, b. Fuel injected by Fuel injecting
pump.
Dr V Venkateswarlu
7

8. 5. Method of ignition:
a. battery or coil ignition, b. Magneto ignition, c. Electronic ignition
6. Method of cooling:
i) Air cooled, ii) Water cooled
7. Cylinder Arrangement:
i) in line type, ii)V type, iii) Opposed cylinder type, iv)Radial type
8. Valve operating system:
i) Overhead, ii) Side valve type
Dr V Venkateswarlu 8

9. Materials used, function and Constructional details of Petrol
Engine Components
Engine consists of the following
parts.
1.Cylinder block
2.Cylinder head
3.Crankcase
4.Piston
5.Piston Rings
6.Piston Pin
7.Connecting Rod
8. Crankshaft
9. Flywheel
10. Valves and valve mechanism
11. Rocker Arm
12. Camshaft
besides the these components engine contain so many
accessories like air cleaner, oil filter, automatic
chokes,
automatic heat controls, spark plug, ignition devices,
carburetors, manifolds, vibration damper etc.
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10. Dr V Venkateswarlu 10

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• The engine consists of several parts,
• To understand the construction of the engine
we have to know the function and
constructional details of at least the main
parts.
• The main parts of an engine are
– Cylinder or Cylinder block
– Cylinder liner
– Piston
– Connecting rod
– Crank shaft
– Piston pin
– Main bearings
– Valves …etc.,
Engine Constructional Details
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Working of an I.C. Engine Model (Petrol)
Fig:1
• What is this ?
• An engine
• What is the function of engine?
• An engine is a energy converting
device.
• Used to convert the heat energy
produced by the combustion of
fuel into mechanical energy.
• This mechanical energy is
utilised for moving an
automobile.
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I.C. Engine Model (Petrol)
Figure 2
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CB
CB Cylinder Block
P Piston
R Connecting Rod
C Crank Shaft
W Water jacket
V Valves
I Inlet Valve
E Exhaust Valve
S Spark Plug
PP Piston pin
PP
Main Parts of an Internal Combustion Engine
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In-line Engine Cylinder Block (4-Cylinders)
Fig:4
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Cylinder Block
• Cylinder block forms the very base of the engine with
cylinders formed in it
• Cylinder block consists of three parts:
• The Cylinders in which pistons move up and
down
• The ports or openings for the valves
• The passages for the flow of cooling water
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Cylinder Block
• In modern engines Cylinder block and Crank case form
a single casting.
• This gives advantages like increased rigidity and
reduced cost.
• Sheet metal core plugs made of steel, copper or brass
are used to close the holes in the casting.
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A Typical Engine Cylinder Block
Fig:3
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In-line Engine Cylinder Block (4 Cylinders)
Fig:5
Cylinders in a line
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Cylinder Liners
• The cylinder block is usually made of grey cast iron
• Grey cast iron has good castability and machining
quality but do not have a good wear resistance
• Cylinders are subjected to high temperatures requiring
wear resistant properties a elevated temperatures
• In order to fulfill such a condition Cylinder Liners are
used.
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Cylinder Liners
• Cylinder liners are made of special alloy cast iron.
• Cylinder liners are of two types:
• Dry Liners
• Wet Liners
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Dry Liners
• Dry liner is made in the
shape of a barrel having
a flange at the top which
keeps it into position in
the cylinder block
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Dry Liners
• Dry liner is made in the shape of a barrel having a
flange at the top which keeps it into position in the
cylinder block
• The entire outer surface of the dry liner bears against
the cylinder block casting
• Thus it is not in direct contact with the cooling water,
hence it is called as dry liner.
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Dry Liners
• Therefore a dry liner has
to be machined
accurately on outer
surface also
• Dry liners thickness
usually ranges from 1.5 to
3 mm
• These liners are
replaced when worn out.
Dry Liners
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Cylinder Liners
Dry Liners
Fig:7
Wet Liner
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Wet Liners
• The outer surface of
these liners have direct
contact with the cooling
water
• Therefore they are
called as Wet Liners
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Wet Liners
• A wet liner is provided with a flange at the top which fits
into the groove in the cylinder block.
• At the bottom either a block or the liner is provided with
grooves, generally three in numbers
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Wet Liners
• Packing rings made of rubber are inserted into the
bottom grooves
• The outer surface of a wet liner does not require
accurate machining
• Wet liners are thicker than dry liners.
• Thickness usually ranges from 1.5 to 6mm
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Materials used for Engine Components
Component
Engine Component Material
Cylinder Block
Grey Cast Iron
Aluminum Alloy
Cylinder Liner Cast Iron
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Component Functions
Cylinder Block
• Forms base of the engine
• Serves as a support and enclosure for
moving parts
• Should have water jackets for cooling
system
Cylinder
Liners
• Forms Cylinder walls
• Should retain a film of lubricant
• Should conduct heat quickly to coolant
Functions of Engine Components
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Cylinder Block, Cylinder Head and Sump
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Summary
In this session we have learnt about
• Construction of a Cylinder Block and Cylinder Liners
• Wet Liners
• Dry liners
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Quiz
1. Cylinder Block is made of
a) Alloy steel
b) Brass
c) Grey Cast Iron
d) Aluminum
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Quiz
2. Cylinder Liners are made of
a) Alloy steel
b) Brass
c) Grey Cast Iron
d) Aluminum alloy
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Assignment
1. Explain the functions of wet liners and dry liners.
2. Explain cylinder block functions and materials.
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