The document provides a comprehensive overview of internal combustion engines, including their introduction, applications, and classifications. It details the working principles of two-stroke and four-stroke engines, the differences between petrol and diesel engines, and the essential parts and nomenclature of these engines. Additionally, the document categorizes engines based on various criteria such as fuel type, cooling system, and ignition method.

1. ME-420 Internal Combustion Engines
Introduction, Applications
&Classifications

2. Content
n Introduction
n Application of IC engines
n Parts of IC Engines
n Classification of IC Engines
n Working of IC Engines
n Difference between Two stroke and Four Stroke
n Difference between SI and CI Engines

3. Introduction
Internal Combustion Engines
Heat Engines
External Combustion Engines
Definition of Heat Engines :-
It is mechanical device , which converts heat
energy into mechanical energy
Example :- Gas turbine power plants ,
Steam power Plants,
Internal Combustion Engines(automobiles)

4. External combustion Engines
n Combustion takes
place away from
work producing
place
n Steam power plants

5. Internal Combustion Engines
Combustion takes Place inside the Cylinder
(i.e., with in the work producing place)
Example :- All Type of automobile engines

6. Basic Principle of IC Engines
Combustion Is Key
To understand the basic idea behind how a
reciprocating internal combustion engine
works, it is helpful to have a good mental
image of how "internal combustion" works.
One good example is an old Revolutionary
War cannon. You have probably seen
these in movies, where the soldiers load
the cannon with gun powder and a cannon
ball and light it. That is internal
combustion,

7. Application of Internal combustion Engines
n Road Vehicles
n Air Craft
n Locomotives
n Pumping sets
n Cinemas
n Hospital
n Several Industrial application

8. Automobile
engineering is the
activity of
designing and
constructing
automobiles

9. Back to Content

10.  1876 – Otto’s first prototype
 1st practical ICE
 Power: 2 hp; Weight: 1250 pounds
 Comp. ratio = 4 (knock limited), 14%
efficiency (theory 38%)
 Today CR = 9 (still knock limited),
30% efficiency (theory 55%)
 1881 – Two stroke engine
 1892 – Diesel’s first prototype
 1921 -Antiknock effect of
tetraethyl lead – General Motors
 1957 – Wankel’s first prototype
 1975 - Catalytic converters,
unleaded fuel
 1980s - Microcomputer control of
engines

11. Parts of an IC Engines (Petrol Engines)
Cylinder
Cylinder head
Piston and piston rings
Connecting Rod
Crank and Crankshaft
Inlet Valve
Exhaust Valve
Inlet manifold
Exhaust manifold
Cam and cam follower
push Rod and Rocker Arm
Crank Case
Flywheel
Carburetor
Spark plug

12. Parts of Diesel Engines

13. Basic Engine Nomenclature
Bore : Inside diameter of the cylinder
Top Dead Center : The extreme position of the piston at the top of the
cylinder(TDC)
Bottom Dead Center : The extreme position of the piston at the bottom of the
cylinder (BDC)
Stroke : The max distance traveled by the piston from TDC to BDC or vice versa
Clearance Volume : The volume contained in the cylinder above the top of the
piston When the piston at the TDC.
Piston Displacement or Swept Volume : The volume swept through by the piston
in moving from TDC to BDC.
Compression ratio : The ratio of the volume when the piston is at BDC to the
volume when the piston is at TDC
Back to Content

14. Classification of an IC Engines
n Based on Working Cycle
n Based on type of fuels used
n Based on Number of strokes
n Based on Cooling system
n Based on number of cylinders used
n Based on Cylinder arrangement
n Based on method of ignition
n Based on their application
n Based on method of Governing

15. Based on working Cycle
n Otto Cycle
n Ex :- Petrol Engines
n Diesel Cycle
n Ex : - Diesel Engines
n Duel Cycle
n Ex :- special purpose
engines

16. Based on types of fuel used
n Petrol Engines
n Diesel Engines
n Gaseous fuels Engines
Based on number of strokes
n Two Stroke Engines
n Power is getting in one revolution of the crank i.e., in two stroke
n Four Stroke Engines
n Power is getting in two revolution of the crank i.e., in four stroke
n Based on Cooling System
n Air cooling
n Water cooling

17. Back
The Two-stroke Cycle

18. Based on number of cylinder
n Single cylider Engines
n Multicylinder Engines
Based on Cylinder arrangements
n Inline Engines
n V – Type Engines
n Radial Engines
n Opposed piston Engines
n Opposed cylinder Engines
n Delta Type Engines
Based on method of ignition
n Spark Ignition Engines(SI Engines)
n Compression ignition(CI Engines)

19. Based on Cooling System
Air Cooling Engines
Water Cooling Engines

20. Based on Cylinder arrangement
Inline Engines V Type Engines

21. Radial Engines Opposed piston Engines Opposed cylinder Engines
Delta type

22. Based on Method of ignition
Spark ignition Engines
Compression Ignition Engines
Spark ignition

23. Based on Application
n Stationary Engines
n Marine Engines
n Portable Engines
n Automobile Engines
n Aero Engines
Based on method of Governing
n Hit & miss governed Engines
n Quality governed Engines
n Quantity governed Engines

24. Ignition system in diesel engines

25. Working of IC Engines
n Working of Two Stroke Engines
Petrol Engines
Diesel Engines
n Working of Four Stroke Engines
Petrol Engines
Diesel Engines

26. Working of Two stroke Diesel Engines
n Based on Diesel Cycle
n Fuel diesel
n Power is produced in every cycle

27. Working of two stroke diesel engines
Power is produced in one
revolution of the crank
shaft and suction,
compression, expansion
and exhaust stroke is
completed in two stroke
only.

28. Working of Two stoke petrol Engines

29. Working of Two stroke Petrol Engines
Back

30. Working of Four stroke Petrol Engines
Power is produced in four stroke
i.e.,two revolution of the crank
shaft
It work on Otto cycle and it completes
in four stroke of the piston
The cycle consisting of following
process
Suction stroke
Compression stroke
Expansion stroke or power stroke
Exhaust stroke
It requires carburetor and spark plug

31. Working of Four stroke Petrol Engines

32. Working of Four stroke diesel engines
Power is produced in four stroke
i.e.,two revolution of the crank
shaft
It work on Diesel Cycle and it
completes in four stroke of the
piston
The cycle consisting of following
process
Suction stroke
Compression stroke
Expansion stroke or power stroke
Exhaust stroke
It consists of fuel injection and
pumping arrangement

33. Working of Four stroke Diesel Engines

34. Difference between Two stroke and Four
Stroke Engines
Aspects Four Stroke Two Stroke
Completion of Cycle The cycle is completed in 4S of
the piston/ one power stroke in 2
revolution of the crank
The cycle is completed in 2S of
the piston/ one power stroke in 1
revolution of the crank
Flywheel required
(heavior or lighter)
Turning moment is not uniform
and hence heavier flywheel is
need
Turning moment is uniform and
hence lighter flywheel is need
Power Produced for some size of
engine
Is small or for the same power
the engine is heavy and bulky
Is more (2 Times ) or for the
same power the engine is light
and compact
Cooling and lubricants
requirements
Lesser cooling &lubricant More cooling and lubrication is
required
Valve and valve mechanism It contains valve and valve
mechanism
No valves
Initial cost Cost is high Initial cost is less

35. Difference between Two stroke and Four Stroke
Engines
Aspects Four Stroke Two Stroke
Volumetric efficiency more less
Thermal and part load
efficiencies
Higher and at part load efficiency
is more
Less and at part load efficiency
is less
application Cars, buses, truces, tractor ,
industrial application and etc..
Lawn movers, scooters, motor
cycles, and etc..

36. Difference between Petrol Engines and Diesel
Engines
PETROL ENGINES DIESEL ENGINES
It works on Otto Cycle It works on Diesel cycle
It draws a mixture of petrol and air during suction
stroke
It draws only air during suction stroke
Carburetor/MPFI is employed to mix air and petrol
during suction stroke.
Injector is employed to inject the fuel at the end of
compression stroke
Pressure at the end of compression is about 10 to 15
bar
Pressure at the end of compression is about 50 bar to
75 bar
The charge is ignited with the help of spark plug Self ignited ( end of compression stroke temperature
is about 600°C)
It has a compression ratio approximately from 6 to 12 It has a compression ratio approximately from14 to22
The maintenance cost is less high
The thermal efficiency is upto about 30% Thermal efficiency is upto 40%

37. Power and Mechanical efficiencies
Indicated power (IP) = (nPmi LANK10)/(6) KW
Brake power(BP) = (2iiNT )/(60*1000) KW
Frictional power(FP) = IP-BP
Mechanical efficiency ηmech = BP/IP
Thermal efficiency ηther = IP/heat input or = BP/ heat input
Volumetric efficiency ηVole = actual volume of the charge drawn/swept volume
Fuel – Air rartio = mass fuel to mass of air

38. ***A course in Internal combustion engines
By V.M. Domkundwar
***A course in Internal combustion engines
By Mathur and sharma
*** Internal combustion engines
By V. Ganesan
*** auto.howstuffworks.com/engine.html/
*** Google search “ animation of working of
internal combustion engines “
Reference to this topic