This presentation discusses internal combustion engines. It provides an introduction and overview of external combustion engines and internal combustion engines. It then focuses on internal combustion engines, describing their main parts like the cylinder block, cylinder head, piston, connecting rod, crankshaft, valves, spark plug, injector, manifold, and camshaft. It also defines important engine terminology and classifications of internal combustion engines. The advantages of internal combustion engines are listed as having higher efficiency than external combustion engines while also being more compact and having a lower initial cost.

1. PRESENTATION
SUB: APPLIED THERMODYNAMICS
TOPIC: INTERNAL COMBUSTION
ENGINE
PRESENTED TO :
SIR GHULAM ABBAS

2. GROUP MEMBERS ARE
SULAIMAN SHAR K16-
PG-11
HUMAYOUN AYOUB K16-
PG-26
MADAN LAL KHATRI K16-
PG-55
MURAD ZADA K16-
PG-70

3. INTRODUCTION TO ENGINE
•Any device which can convert heat energy of
fuel into mechanical energy is known as
engine or heat engine.
•Engine is widely used in automobile
industries or we can say that engine is the
heart of an automobile.
Basically engine may be classified into two
types.
1. External Combustion Engine (E.C Engine)
2. Internal Combustion Engine (I.C Engine)

4. 1. External Combustion Engine (E.C Engine):
It is an engine in which combustion of fuel take place
outside of the engine. In this type of engine heat,
which is generated by burning of fuel is use to
convert the water or other low boiling temperature
fluid into steam. This high pressure steam used to
rotate a turbine. In this engine we can use all solid,
liquid and gases fuel.
These engines are generally used in driving
locomotive, ships, generation of electric power etc.
Advantages of E.C. engine-
In these engines starting torque is generally high.
Because of external combustion we can use
cheaper fuels as well as solid fuel.
They are more flexible compare to internal
combustion engines.

6. 1.Internal Combustion Engine (I.C Engine):
The first commercially successful internal
combustion engine was created by Étienne
Lenoir around 1859.
The first modern internal combustion engine was
created in 1876 by Nikolaus Otto (see Otto engine).
The internal combustion engine (IC Engine) is a
heat engine that converts heat energy (chemical
energy of a fuel) into mechanical energy (usually
made available on a rotating output shaft).

7. Types of Internal Combustion Engine (I.C Engine):
There are two basic types of IC engine.
1. Rotary engines.
2. Reciprocating engines.
 In rotary engines, a rotor rotates inside the engine to produce
power.
 In the case of the reciprocating engines, a piston reciprocates
within a cylinder. The reciprocating motion of the piston is
converted into the rotary motion of the vehicle's wheels. In
automobiles, reciprocating engines are used. They are the most
widely used type of engine.
Reciprocating engines are classified into two types:
1) Spark ignition (SI) engines (petrol or gasoline engine )
2) Compression ignition (CI) engines(diesel engine )

8. Main Parts of an Internal Combustion Engine:
1.Cylinder block
2. Cylinder head
3. Piston
4. Piston rings
5. Connecting rod
6. Crankshaft
7. Engine bearing
8. Crankcase
9. Valves
10. Spark plug
11. Injector
12. Manifold
13. Camshaft
14. Gudgeon pin or piston pin
15. Pushrod
16. Flywheel

9. 1)Cylinder block
Cylinder is the main body of IC
engine. Cylinder is a part in
which the intake of fuel,
compression of fuel and burning
of fuel take place. The main
function of cylinder is to guide
the piston. It is in direct contact
with the products of combustion
so it must be cooled. For cooling
of cylinder a water jacket (for
liquid cooling used in most of
cars) or fin (for air cooling used
in most of bikes) are situated at
the outer side of cylinder.
it is made by high grade cast
iron. It is made by casting and
usually cast in one piece.

10. 2. Cylinder head:
The top end of cylinder is closed
by means of removable cylinder
head. There are two holes or ports
at the cylinder head, one for intake
of fuel and other for exhaust. Both
the intake and exhaust ports are
closed by the two valves known as
inlet and exhaust valve.
The main function of cylinder
head is to seal the cylinder block
and not to permit entry and exit of
gases on cover head valve engine.
Cylinder head is usually made by
cast iron or aluminum. It is made by
casting or forging and usually in
one piece.

11. 3. Piston:
A piston is fitted to each cylinder
as a face to receive gas pressure
and transmit the thrust to the
connecting rod. It is the prime
mover in the engine. The main
function of piston is to give tight seal
to the cylinder through bore and
slide freely inside of cylinder. Piston
should be light and sufficient strong
to handle the gas pressure
generated by combustion of fuel.
The piston is made by aluminum
alloy and sometimes it is made by
cast iron because light alloy piston
expands more than cast iron so they

12. 4. Piston rings:
A piston must be a fairly loose fit
in the cylinder so it can move freely
inside the cylinder.
To provide a good sealing fit and
less friction resistance between the
piston and cylinder, pistons are
equipped with piston rings.
 A small two stroke engine has
two piston rings to provide good
sealing but in a four stroke engine
has an extra ring which is known as
oil ring.
Piston rings are made of cast iron
of fine grain and high elastic
material which is not affected by
the working heat. Sometimes it is
made by alloy spring steel.

13. 5. Connecting rod:
Connecting rod connects the
piston to crankshaft and transmits
the motion and thrust of piston to
crankshaft.
It converts the reciprocating
motion of the piston into rotary
motion of crankshaft.
There are two end of connecting
rod one is known as big end and
other as small end.
The connecting rods are made of
nickel, chrome, and chrome
vanadium steels. For small engines
the material may be aluminum.

14. 6. Crankshaft
The crankshaft of an internal
combustion engine receives the
efforts or thrust supplied by piston to
the connecting rod and converts the
reciprocating motion of piston into
rotary motion of crankshaft.
The shape and size of crankshaft
depends on the number and
arrangement of cylinders.
It is usually made by steel forging,
but some makers use special types of
cast-iron such as spheroidal graphitic
or nickel alloy castings which are
cheaper to produce and have good
service life.

15. 7. Engine bearing:
Everywhere there is rotary
action in the engine, bearings
need. Bearings are used to
support the moving parts. The
crankshaft is supported by
bearing.
In an IC engine sliding and
rolling types of bearing used.
The main function of bearings is
to reduce friction between these
moving parts.
The typical bearing half is made
of steel or bronze back to which a
lining of relatively soft bearing
material is applied.

16. 8. Crankcase:
The main body of the engine
to which the cylinder are
attached and which contains
the crankshaft and crankshaft
bearing is called crankcase.
It serves as the lubricating
system too and sometime it is
called oil sump. All the oil for
lubrication is placed in it.

17. 9. Valves:
To control the inlet and exhaust
of internal combustion engine,
valves are used.
The number of valves in an
engine depends on the number of
cylinders.
Two valves are used for each
cylinder one for inlet of air-fuel
mixture inside the cylinder and
other for exhaust of combustion
gases.
The valves are fitted in the port
at the cylinder head by use of
strong spring. This spring keep
them closed. Both valves usually
open inwards.

18. 10. Spark plug:
It is used in spark ignition engine.
The main function of a spark plug
is to conduct the high potential from
the ignition system into the
combustion chamber to ignite the
compressed air fuel mixture. It is
fitted on cylinder head.
The spark plug consists of a
metal shell having two electrodes
which are insulated from each
other with an air gap.
When high potential current
supply to spark plug it jumping from
the supply electrode and produces
the necessary spark.

19. 11. Injector:
Injector is usually used
in compression ignition
engine. It sprays the fuel
into combustion chamber
at the end of compression
stroke.
 It is fitted on cylinder
head.

20. 12. Manifold:
The main function of
manifold is to supply the
air fuel mixture and
collects the exhaust gases
equally form all cylinder.
In an internal
combustion engine two
manifold are used, one for
intake and other for
exhaust.
They are usually made
by aluminum alloy.

21. 13. Camshaft:
Camshaft is used in IC
engine to control the opening
and closing of valves at
proper timing.
For proper engine output
inlet valve should open at the
end of exhaust stroke and
closed at the end of intake
stroke. So to regulate its
timing, a cam is use which is
oval in shape and it exerts a
pressure on the valve to
open and release to close. It
is drive by the timing belt
which drives by crankshaft.
It is placed at the top or at
the bottom of cylinder.

22. 14. Gudgeon pin or piston
pin:
These are hardened
steel parallel spindles
fitted through the piston
bosses and the small end
bushes or eyes to allow
the connecting rods to
swivel. It connects the
piston to connecting rod.
It is made hollow for
lightness.

23. 15. Pushrod:
Pushrod is used when
the camshaft is situated
at the bottom end of
cylinder. It carries the
camshaft motion to the
valves which are
situated at the cylinder
head.

24. 16. Flywheel:
A flywheel is
secured on the
crankshaft. The
main function of
flywheel is to
rotate the shaft
during
preparatory
stroke. It also
makes crankshaft
rotation more
uniform.

25. Basic Engine Terminology:
1. Top dead center (T.D.C.)
In a reciprocating engine the piston moves to and
fro motion in the cylinder. When the piston moves
upper direction in the cylinder, a point at which
the piston comes to rest or change its direction
known as top dead center. It is situated at top
end of cylinder.
2. Bottom dead center (B.D.C.)
When the piston moves in downward direction, a
point at which the piston come to rest or change
its direction known as bottom dead center. It is
situated in bottom side of cylinder.

27. 3. Stroke (L)
The maximum distance travel by the piston in single
direction is known as stroke.
It is the distance between top dead center and bottom
dead center.
4. Stroke length:
The distance between two dead centres(DC).
5. Bore (b)
The inner diameter of cylinder known as bore of cylinder.
6. Maximum or total volume of cylinder (Vtotal)
It is the volume of cylinder when the piston is at bottom
dead center. Generally, it is measure in centimeter cube
(c.c.).
7. Minimum or clearance volume of cylinder (Vclearance)
It is the volume of cylinder when the piston is at top dead
center.

28. 8. Swept or displace volume (Vswept)
It is the volume which swept by the piston. The difference between
total volume and clearance volume is known as swept volume.
Swept volume = Total volume - Clearance volume
9. Clearance volume(Vs):
Distance between dead centre(DC) to head.
Or Distance between inner dead centre(IDC) to head.
10. Compression ratio
The ratio of maximum volume to minimum volume of cylinder is
known as the compression ratio. It is 8 to 12 for spark ignition
engine and 12 to 24 for compression ignition engine.
Compression ratio = Total volume / Clearance volume
11. Ignition delay
It is the time interval between the ignition start (spark plug start in
S.I. engine and inject fuel in C.I. engine) and the actual
combustion starts.

29. 12. Stroke bore ratio
Stroke bore ratio is the ratio of bore (diameter of cylinder) to length of
stroke. It is generally equal to one for small engine and less than one
for large engine.
Stroke bore ratio = inner diameter of cylinder / length of stroke
13. Mean effective pressure
The average pressure acting upon the piston is known as mean
effective pressure. It is given by the ratio of the work done by the
engine to the total volume of engine.
Mean effective pressure = Work done by engine / Total volume of
cylinder
14.Cubic capacity:
It is volume of the cylinder.
Cubic capacity= n*volume of cylinder.
Where n is number of cylinder

30. Classification of IC Engine:
Internal combustion engines can be classified into a large
number of types based on several criteria. The classification
of IC engines is given below:
1)Based on the fuel used
a) Diesel Engine
b) Petrol Engine (or Gasoline Engine)
2)Based on the type of cycle
a) Otto Cycle Engine
b) Diesel Cycle Engine
c) Dual Cycle Engine

31. 3)Based on the number of cylinders
a)Single Cylinder Engine
b)Multi cylinder Engine
1) Twin Cylinder Engine
2) Three Cylinder Engine
3) Four Cylinder Engine
4) Six Cylinder Engine
5) Eight Cylinder Engine
6) Twelve Cylinder Engine
7) Sixteen Cylinder Engine
4)Based on the type of ignition
a) Spark Ignition Engine (S.I. Engine)
b) Compression Ignition Engine (C.I. Engine)
5)Based on the lubrication system used
a) Dry sump lubricated engine
b) Wet sump lubricated Engine

32. 6)Based on the cooling system used
a) Air-cooled Engine
b) Water-cooled Engine
c) Based on the arrangement of valves
d) L-head Engine
e) I-head Engine
f) T-head Engine
g) F-head Engine
7)Based on the position of cylinders
a) Horizontal Engine
b) Vertical Engine
c) Radial Engine
d) Opposed Piston Engine
e) Opposed Cylinder Engine
f) V Engine
g) W Engine
h) Inline Engine

33. 3)Based on the number of strokes per
cycle
a) Two-stroke Engine
b) Four-stroke Engine
Two stroke engine

35. Advantages of I.C. engine-
It has overall high efficiency over E.C.
engine.
These engines are compact and required
less space.
Initial cost of I.C. engine is lower than E.C.
engine.
This engine easily starts in cold because of
it uses high volatile fuel.