Positive Displacement Machines can be easily
reversed.
A reciprocating compressor can be converted into a
reciprocating Engine.
Internal Combustion Engines
P M V SUBBARAO
Associate Professor
Mechanical Engineering Department
IIT Delhi
A Pure Passion, Lead to Most Essential Technology…..
A Dream Machine…
• To search for a better horse.
• Motive Power as much as we need and Whenever we need…..
• The automobile as we know it was not invented in a single day by a
single inventor.
• The history of the automobile reflects an evolution that took place
worldwide.
• It is estimated that over 100,000 patents created the modern
automobile.
• A simple anatomy creates a versatile environment to convert
chemical energy of fuel into Mechanical Motive Power.
A Simple Anatomy
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A cylinder
A Piston
A Connecting Rod
A Crank
• Quite fuel energy to Most
active mobile power.
• What lead to the invention
of Piston & Cylinder?
• The effect of 130 years of
evolution!?!?!
Daily Routine
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Inhalation of fresh air.
Intake of diet.
Compression of air.
Digestion of intake with air.
Generation of Mechanical Motion.
Exhalation of waste.
A cyclic creature called natural air breathing
Machine.
• Actions are discrete but final outcome is
continuous.
Strategies for Execution of Routine
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Sequence of Events.
Duration of events.
Pace of realization of an event.
Magnitude of each event.
This leads to classification of ICengines.
Engine Classifications
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Cycle (2- vs. 2-stroke)
Valve vs. Port (OH Cam, etc.)
Fuel (Gasoline, NG, diesel)
Fuel/Air Mixing (carburetor, fuel injection)
Ignition (spark, compression)
Load Control (fuel control, air control)
Cooling (wet, air, uncooled)
Application (road, RR, marine, airborne, utility, stationary)
Design (rotary, recip)
Major operation Strategies
• Efficient Space Management: 4-stroke cycle:
Requires two complete revolutions to complete a
cycle
• Efficient Time Management: 2-stroke cycle:
Requires one complete revolution to complete a
cycle
1
4
3
2
(Wastage of Time)
Wastage of Space
The instantaneous active
cylinder volume is a strong
function of angular
displacement of crank
angle.
The p-V diagrams can be
easily translated into p-q
diagram.
P-q diagram gives a true
picture of engine operation.
Cold Period of Operation
Hot Period of Operation
Co-ordination of Valve Action with Piston Displacement