I.C.ENGINES !!!!!!
DO WE REALLY NEED ‘EM?
I have always considered that the substitution of the
Internal Combustion Engine for the horse marked a very
gloomy milestone in the progress of mankind.
-Winston Churchill
ENGINES
BOON OR BANE ?
• Greatest invention since the wheel?
• Made transportation easy!
• Made life easy!
OR DID IT?
• Increased pollution
• Increased fossil fuel consumption
• Increased congestion on roads
BUT………..
• WHETHER WE LIKE IT OR NOT….
CAN WE DO WITHOUT IT?
• DO WE HAVE VIABLE ALTERNATIVES?
THINK………
• AS OF TODAY WE HAVE NO ANSWER
• MAY BE FOR AT LEAST 20 YEARS MORE!
• SO WE ARE STUCK WITH IT………!
SO WE STUDY IT………….!
And so on to the course:
Engine
An engine is motor which
converts chemical energy into
mechanical energy
History
• Otto Cycle: Dr. Nicolaus Otto -1876
• 2-Cycle Engine; Du gal Clerk -1878
History
• Diesel Engine; Dr. Rudolph Diesel -1895
CLASSIFICATION OF INTERNAL
COMBUSTION ENGINES
VARIOUS TYPES OF ENGINES
Engines can also be classified according to
whether the fuel is burnt inside or outside the
engine
INTERNAL
COMBUSTION ENGINES
EXTERNALENGINES
(Steam Engine)
CLASSIFICATION OF ENGINES
Engines can be classified according to the
fuel they use
PETROL ENGINES
DIESEL ENGINES
The engines may be classified according to
1.Number of cylinders
2.Cylinder arrangements
3.Valve arrangements
4.Speed of the engines
5.Cooling system
6.Lubrication system used
7.Number of strokes used.
Vertical Engines
HORIZONTAL ENGINE
ROTARY ENGINE
RADIAL ENGINE
V TYPE STIRLING ENGINES
Terminology
Stroke is the distance of the piston travels
from BDC to TDC
stroke
TDC
BDC
FOUR STROKE ENGINES
FIRST STROKE –SUCTION STROKE
While the inlet valve is open ,the descending piston draws fresh
petrol and air mixture into the cylinder.
Fig.
FOUR STROKE ENGINES
FIRST STROKE –SUCTION STROKE
While the inlet valve is open ,the descending piston draws fresh
petrol and air mixture into the cylinder.
IN LET VALVE
OPEN POSITION
EXHAUST VALVE
CLOSE POSITION
Fig.
FOUR STROKE ENGINES
FIRST STROKE –SUCTION STROKE
While the inlet valve is open ,the descending piston draws fresh
petrol and air mixture into the cylinder.
IN LET VALVE
OPEN POSITION
EXHAUST VALVE
CLOSE POSITION
Fig.
FOUR STROKE ENGINES
FIRST STROKE –SUCTION STROKE
While the inlet valve is open ,the descending piston draws fresh
petrol and air mixture into the cylinder.
IN LET VALVE
OPEN POSITION
EXHAUST VALVE
CLOSE POSITION
Fig.
FOUR STROKE ENGINES
FIRST STROKE –SUCTION STROKE
While the inlet valve is open ,the descending piston draws fresh
petrol and air mixture into the cylinder.
IN LET VALVE
OPEN POSITION
EXHAUST VALVE
CLOSE POSITION
Fig.
SECOND STROKE-COMPRESSION STROKE
While the valves are closed,the rising piston
compresses the mixture to a pressure about 7-8atm;
the mixture is then ignited by the spark plug.
IN LET VALVE
CLOSE POSITION
EXHAUST VALVE
CLOSE POSITION
Fig.
SECOND STROKE-COMPRESSION STROKE
While the valves are closed,the rising piston
compresses the mixture to a pressure about 7-8atm;
the mixture is then ignited by the spark plug.
IN LET VALVE
CLOSE POSITION
EXHAUST VALVE
CLOSE POSITION
Fig.
SECOND STROKE-COMPRESSION STROKE
While the valves are closed,the rising piston
compresses the mixture to a pressure about 7-8atm;
the mixture is then ignited by the spark plug.
IN LET VALVE
CLOSE POSITION
EXHAUST VALVE
CLOSE POSITION
Fig.
SECOND STROKE-COMPRESSION STROKE
While the valves are closed,the rising piston
compresses the mixture to a pressure about 7-8atm;
the mixture is then ignited by the spark plug.
IN LET VALVE
CLOSE POSITION
EXHAUST VALVE
CLOSE POSITION
Fig.
THIRD STROKE-POWER STROKE
While the valves are closed the pressure of the
burned gases of the combustion forces push the
piston downwards.
IN LET VALVE
CLOSE POSITION
EXHAUST VALVE
OPEN POSITION
Fig.
FOURTH STROKE-EXHAUST STROKE
The exhaust valve is open and the rising
piston discharges the spent gases from the
cylinder.
Fig.
SUCTION STROKE
COMPRESSION STROKE
POWER STROKE
EXHAUST STROKE
Petrol Engine Vs Diesel Engine _ Difference _ Comparision.mp4
Petrol (Gasoline) Engine vs Diesel Engine [720p].mp4
ADVANTAGES OF FOUR STROKE ENGINES
1.Less fuel consumption
2.Thermal efficiency is more
3.More volumetric efficiency
4.Less wear and tear.
DISADVANTAGES OF FOUR STROKE ENGINES
1.More components
2.Separate valve operating mechanism is required.
3.More cost
4.More complicated design.
Two-Stroke Engine
Upward Stroke
• Piston moving upward
• Crankcase pressure drops
• Intake port exposed
• Intake air enters through
carburetor pulls fuel and
oil into crankcase
Downward Stroke
•
•
•
•
Piston moving downward
Exhaust port exposed
Exhaust gases expelled
Complete exhausting occurs
when transfer ports are
opened
• New charge rushes in
Working of 2 – Stroke engine
How 2 Stroke Engine Works.mp4
4 – Stroke Vs 2 - Stroke
2 Stroke Engine Vs 4 Stroke Engine _ Difference _ Comparison _
Opinion.mp4

Lets take a quiz to see what you have
learned!
Back
Quiz
1. The ____ controls the amount of intake
and the release of exhaust.
a. head
b. valves
c. coolant
d. connecting rod
2.
The _____ stroke is the ignition of the
compressed fuel-air mixture.
a. Exhaust
b. Combustion
c. Compression
d. Intake
3.
The most common type of engine?
a. diesel engines
b. 2-stroke engines
c. rotary engines
d. 4-stroke engines
4.
What part of the engine converts up and
down motion into a rotation motion?
a. crankshaft
b. piston
c. valve cover
d. camshaft
5.
What is the name
of the part listed?
a. intake valve
b. piston
c. oil pan
d. spark plug
Most high speed compression engines operates on......
A. Diesel cycle
B. Otto cycle
C. Dual combustion cycle
C. Carnot cycle
Which of the following is not an internal
combustion engine.......
A.2 stroke petrol engine
B.4 stroke petrol engine
C.Diesel engine
D.Steam turbine
The thermal efficiency of two stroke cycle
engine is.....a four stroke cycle engine
A.Equal to
B.Less than
C.Greater than
D.None of the above
A two stroke cycle engine gives......the
number of power strokes as compared to the
four stroke cycle engine,at the same engine
speed
A.Half
B.Same
C.Double
D.Four times
In a four stroke engine, the working cycle is
completed in.......
A.One revolution of the crankshaft
B.Two revolution of the crankshaft
C.Three revolution of the crankshaft
D.Four revolution of the crankshaft
The thermodynamic cycle in which petrol
engine works, is......
A.Otto cycle
B.Diesel cycle
C.Rankine cycle
D.Stirling cycle
Which of the following does not relate with
spark ignition engine......
A.Ignition coil
B.Spark plug
C.Distributor
D.Fuel injector
The power developed by the engine cylinder
of an I.C. engine is known as.......
A.Indicated power
B.Break power
C.Actual power
D.None of the above
Valve Operation
Camshaft and Valves [720p].mp4
Valve timing diagram
The valve timing diagram is a graphical representation of opening and closing
of inlet valve and exhaust valve
IC Engine Valve and Port Timing Diagram.mp4
Port timing diagram
Port Timing diagram illustrates how the events such as the Inlet port,
Exhaust port and Transfer ports are open and closes
Air Standard Cycles
P
Otto Cycle
1
3
2
3
4
2
TDC
4
BDC
1
BDC
TDC
• 1-2 Isentropic compression from BDC to TDC
W12  m  u2  u1 
v
T
3
• 2-3 Isochoric heat input (combustion)
Q23  m  u3  u2 
• 3-4 Isentropic expansion (power stroke)
W34  m  u3  u4 
4
2
• 4-1 Isochoric heat rejection (exhaust)
Q41  m  u4  u1 
1
s
65
Thermodynamic Otto Cycle
Air-standard analysis is a simplification of the real cycle that includes the following
assumptions:
1) Working fluid consists of fixed amount of air (ideal gas)
2) Combustion process represented by heat transfer into and out of the cylinder from an
external source
3) Differences between intake and exhaust processes not considered (i.e. no pumping work)
4) Engine friction and heat losses not considered
Fuel-Air Models for Engine Cycles
More accurate models are used for properties of each constituents.
Process
SI Engine
CI Engine
Intake
Air+Fuel
+Residual gas
Air+ Recycles gas +
Residual gas
Compression
Air+Fuel vapour
+Residual gas
Air+ Recycles gas +
Residual gas
Expansion
Combustion
products
Combustion Products
Exhaust
Combustion
products
Combustion Products
SI Engine Cycle vs Air Standard Otto Cycle
FUEL
A
Ignition
I
R
Fuel/Air
Mixture
Combustion
Products
Actual
Cycle
Intake
Stroke
Compression
Stroke
Power
Stroke
Qin
Otto
Cycle
Air
Exhaust
Stroke
Qout
TC
BC
Compression
Process
Const volume
heat addition
Process
Expansion
Process
Const volume
heat rejection
Process
Actual SI Engine cycle
Total Time Available: 10 msec
Ignition
Air Standard Vs Actual Otto Cycle
Comparison between air standard and actual cycle
The actual cycles for internal combustion engines differ from air-standard
cycles in many respects. These differences are mainly due to:
(i) The working substance being a mixture of air and fuel vapour or finely
atomized liquid fuel in air combined with the products of combustion
left from the previous cycle.
(ii) The change in chemical composition of the working substance.
(iii) The variation of specific heats with temperature.
(iv) The change in the composition, temperature and actual amount of fresh
charge because of the residual gases.
(v) The progressive combustion rather than the instantaneous combustion.
(vi) The best transfer to and from the working medium.
(vii) The substantial exhaust blowdown loss, i.e., loss of work on the expansion
stroke due to early opening of the exhaust valve.
(viii) Gas leakage, fluid friction etc., in actual engines.
• Out of all the above factors, major
influence is exercised by,
(i) Time loss factor i.e, loss due to time
required for mixing of fuel and
air
and also for combustion.
video combustion in cylinder - YouTube.flv
• (ii) Heat loss factor i.e, loss of heat from
gases to cylinder walls.
• (iii) Exhaust blowdown factor I.e. loss of
work on the expansion stroke due to
early opening of the exhaust valve
Time loss factor
Heat loss
How Car Cooling System
Works.mp4
Exhaust blowdown
Loss due to rubbing friction
lubrication system.FLV
Summary