1. Internal combustion engine

2. Definition of I.C.E and E.C.E
I.C.E (internal combustion engine)
-----is a kind of engine that operates by burning its fuel inside
the engine. Example- petrol engine, diesel engine etc.
E.C.E (external combustion engine)
-----is a kind of engine that operates by burning its fuel outside
the engine. Example- steam engine.

4. Applications of IC Engines:
Mainly used as ‘prime movers’, e.g. for be the propulsion of a vehicle i.e.,
car, bus, truck, locomotive, marine vessel, or airplane. Other applications
include stationary saws, lawn mowers, bull-dozers, cranes, electric
generators, etc.

5. Classifications of IC Engines:
IC engines can be classified according to:
• Number of cylinders – 1, 2, 3, 4, 5, 6 to 16 cylinder engines.
• Arrangement of cylinders – Inline, V-type, Flat type, etc.
• Type of cooling – Air-cooled, Water-cooled, etc.
• Number of strokes per cycle – 2-stroke, 4-stroke engines.
• Type of fuel burned – Petrol, diesel, CNG, etc.
• Method of ignition – Spark Ignition (SI), Compression
Ignition (CI).
• Cycle of operation – Otto cycle engine, Diesel cycle engine.
• Primary mechanical motion – Reciprocating, Rotary.
• Speed of engine – Slow speed, Medium speed, High speed.

6. Basic parts of a 4 stroke Petrol Engine

7. Main Components of I.C Engine
Cylinder Block
•“Backbone” of the engine.
•Supports / aligns most other
components.
Cylinder Head
•Contains the valves and the intake
and exhaust ports.
•In Petrol engine, cylinder head
contains spark-plug.
•In Diesel engine, cylinder head
contains fuel injection valve or
nozzle.

8. Main Components of I.C Engine
Valves
Each cylinder has:
•Intake valve
•Exhaust valve
Camshaft
• The camshaft has intake and
exhaust cams for operating the valves.
• Cams open the intake and exhaust
valves at correct time and for correct
duration.

9. Main Components of I.C Engine
Piston
•A movable part fitted into a cylinder,
which can receive and transmit power.
•Through connecting rod, it forces the
crank shaft to rotate.
Piston Rings
•Maintain good seal between the piston
and the cylinder walls.
•There are two types of pistons rings:
compression rings and oil rings.
Connecting Rod
• Attaches piston to the crank shaft .

10. Main Components of I.C Engine
Crankshaft
• Principle rotating part of the
engine.
• Works with connecting rod to
change reciprocating to rotary
motion.
Flywheel
• Attached to the crankshaft
• Maintains uniform rotation of the
crankshaft.

12. Four Stroke Petrol Engine

13. Four Stroke Petrol Engine

14. Four Stroke Diesel Engine

15. Four Stroke Diesel Engine

16. I.C Engine Terminology
• Bore
• Top Dead Centre (TDC)
• Bottom Dead Centre (BDC)
• Stroke
• Clearance Volume (Vc)
• Swept Volume(Vs)/Displacement Volume
*Swept volume = Vs = A x L = (πD2/4) x L
where A = Cross sectional area of the piston
in Sq.m, L = Stroke in m and
D = Cylinder bore i.e., inner diameter of the
cylinder in m.
• Compression Ratio
Compression Ratio=(Vs+ Vc)/ Vc

17. In a petrol engine, the explosion process is:
 Intake stroke – Inlet valve opens and the mixture
of air-fuel (charge) are sucked, piston goes down.
 Compression stroke – Both the inlet and outlet
valves are closed. Piston goes up and mixture of
fuel & air is compressed.
 Ignition/power stroke – Mixture of air-fuel is
ignited through the use of a spark plug, piston
goes down.
 Exhaust stroke – Exhaust valve opens, piston goes
up, pushes exhaust through the exhaust valve.
Explosion Process of Petrol Engine and Diesel Engine
In a diesel engine, the explosion process is:
 Intake stroke – Inlet valve opens and air is sucked,
piston goes down.
 Compression stroke – Both the inlet and outlet
valves are closed. Piston goes up and air
compressed (heated in excess of 540°C).
 Ignition/power stroke – Fuel is injected in the
form of spray (at right time) and ignited through
the use of fuel injector, piston goes down.
 Exhaust stroke – Exhaust valve opens, piston goes
up, pushes exhaust through the exhaust valve.

19. Petrol Engine Diesel Engine
Works on Otto or Constant Volume Cycle Works on Diesel or Constant Pressure Cycle
Uses mixture of Air – Fuel during intake. Uses only Air during intake.
Petrol engines are lighter and cheaper. Diesel engines are heavier and costly.
High speed engines. Relatively low speed engines.
Compression Ratio Low ( 6 to 10 ). Compression Ratio High ( 15 to 25 )
Maintenance cost less. Maintenance cost high.
Thermal efficiency less than diesel engine
(upto 26 %).
Thermal efficiency more than petrol engine
(upto 40 %).
Combustion takes place through spark plug. Fuel injector nozzle is used to inject the fuel
in the combustion chamber.
Generally employed in light duty vehicles
(i.e. - cars, motorcycles etc.)
Generally employed in heavy duty vehicles
(i.e. – buses, trucks etc.)
Difference Between Petrol Engine And Diesel
Engine

20. Electric Car

21. Electric Car

22. Solar Engine