The diesel engine was invented during the industrial revolution by a German engineer. Rudolf Diesel grew up in France but then left for England during the Franco-German war. ... By studying thermodynamics, Diesel found he could make a smaller, internal combustion engine that would convert all heat into work.

1. Basic Principales
of diesel engine

2. Content..
• Objectives.
• History of Diesel Engine.
• Introduction.
• Intake stroke.
• Power stroke.
• Exhaust stroke.
• Compression Stroke.
• Combustion stroke.
• Piston Crown in a 2-stroke Engine.
• Need of the Piston Crown in a 2-stroke Engine.
• pV Graph of the Diesel Engine.
• Advantages and disadvantages of 2- stroke engine.
• Difference between 4-stroke engine & 2-stroke engine.
• Different between Diesel and Petrel Engine.

3. Objectives..
• To know about history of 4 stroke and 2 stroke engine.
• To know about 4 stroke engine main part and working of engine.
• To identify four stroke main parts.
• To know about two stroke engine main part and two stroke main
part.
• To identify need of piston crown and p-v graph of diesel engine.
• To identify advantage and disadvantage of 2 stroke engine.
• To know about different between 4 stroke and 2 stroke engine.
• To identify different between diesel and petrol engine.

4. History of Diesel Engine
The first person to build a working four stroke engine, a
stationary engine using a coal gas air mixture for fuel, was
German engineer Dr. Nikolaus Otto. This is why the four
stroke principle today is commonly known as the otto
cycle and four stroke engines using spark plugs often are
called otto engines.

5. 2- Stroke Diesel Engine
• Sir Dugald Clerk was a Scottish engineer who
designed the world’s first successful two stroke
engine in 1878 and patented it in England in 1881.

6. 4 – Stroke diesel engine
Rudolf Christin Karl Diesel was a German inventor
and mechanical engineer, famous for the invention
of the 4-stroke diesel engine.

7. Introduction
Four Stroke Diesel Engine
Four stroke engine was first demonstrate by Nicolaus
Otto in 1876,hence it is also known as Otto cycle. It
consist of 4 stroke , one cycle operation is completed
in 4 stroke of the piston, That is one cycle is
completed in every 2 revolutions of the crankshaft.
Each stroke consist of 180 ͦͦ, of crankshaft rotation
and hence a cycle consist of 720 ͦͦͦ , of crankshaft
rotation.

8. Two Stroke Diesel Engine.
Two stroke engine is fist described by du gal clerk in
1878. In two stroke engine cycle is completed in
every revolution of crankshaft.

9. Intake stroke.
• The piston is at the top most position
in the cylinder, TDC. ( Top Dead
Center )
• Inlet valve is open and exhaust valve
is closed.
• The piston moves down towards BDC
( Bottom Dead Center ).
• This creates a low pressure in inside
the cylinder.
• Due to the pressure difference air
comes inside through inlet valve.

10. Compression stroke.
• Both the valves are closed.
• And the piston moves towards
TDC and compresses the air.
• This increases the temperature
and pressure of the air.

11. Power stroke
• Both the valves remain closed.
• When the piston reaches TDC the fuel
is sprinkled by the Fuel Injector.
• And the fuel mixture is ignited due to
high temperature & pressure
generated inside the cylinder & push
down the piston to BDC.

12. Exhaust stroke
• When the piston reaches BDC the
exhaust valve is open and the inlet
valve is closed.
• The piston moves upwards towards
TDC pushing the burnt gases outside
the cylinder via exhaust valve.

13. Compression Stroke
• When piston moves from BDC to TDC , its first closes
the transfer port Than excuse port
• The charge of air fuel mixture in the chamber
prespreised and Creates High temperature.
• At the sames time a vacuum is developing in the
crankcase and fresh charge is being
• The piston moves towards TDC ,the diesel added to
prespreised and Height temperature gas which In
turn Ignites the whole mixture inside the cylinder
and forces the piston to moves downward.

14. Combustion stroke
• The stroke both the ports still closed condition, the
pressure of the expanding gases forces the piston
towards BDC.
• The pressure in crankcase is already rising.
• Later in down stroke exhaust port will be open and
forces out the burnt gases .
• Very shortly After that the inlet/ transfer port will
also open to intake the fresh charge of fuel mixture
and engine is ready to start of the cycle.

15. Piston Crown in a 2-stroke Engine.
• Piston crown forms the lower part of the combustion
chamber in a marine diesel engine.
• It seals the cylinder & transmits the gas pressure to
the connecting rod.
• As per the engine requirement,
different types of crowns are used.

16. Need of the Piston Crown in a 2-
stroke Engine
• Convert the pressure developed in ignition stroke to
a downward force – carry the force to the piston rod.
• Sustain pressure waves generated by occasional
knocking.
• Act as a thermal barrier between cylinder & crank
area.
• Controls knocking & helps more uniform combustion.
• Proper design would reduce the piston weight &cost.
• Provide channels & cavities for the favourable
reception & redirection of jets of flame issuing from
the pre-combustion chamber.

17. pV Graph of the Diesel Engine.
• The pressure-volume (Pv) diagram is drawn by
measuring the pressure inside the cylinder,& plotting
it’s value against the angle of the crankshaft.

19. Advantages and disadvantages of 2-
stroke engine
 Advantages
• One cycle completed in every revolution of
crankshaft.
• It is more compact, required less space and lighter
in weight than four stroke engine.
• Easy to manufacture and low cost.
• The design and construction is much simpler.
• Gives less torsional oscillation.
• Requires less spare parts.
• Easy to maintenance.

20.  Disadvantages
• High fuel consumption.
• Compression ratio and thermal efficiency is less
than that of four stroke engine of the same
dimension.
• Consume more lubricating oil.
• More wear and tear of moving parts hence it gives
loud noise.

21. Difference between 4-stroke engine
& 2-stroke engine
4-stroke Engine 2-stroke Engine
One cycle completed in every 2
revolution of crankshaft.
One cycle completed in every
revolution of crankshaft.
More moving parts. Less moving parts.
More maintenances. Less maintenance.
More expansive. Less expensive.
Produce more pollution. Less pollution.
Long engine life. Short engine life.
Complex design. Simpler design.

22. Different between Diesel and Petrel
Engine
Diesel Engine Petrel Engine
Produce top torque at low rpm. Produce top torque at high rpm.
some diesel engine are noisy. Petrol engines are quiet
Fewer mechanics understand
diesel engine.
More mechanics understand
petrol engine.
More complex fuel systems. More complex electrical system.
More costly to services. Cheaper to service.
less fuel consumption. More fuel complex.
Higher maintenance cost . Lower maintenance cost.

23. Summary
 Diesel engine relies upon compression ignition
piston approaches TDC,fuel is injected.
 Ignition instantly occurs,causing a rapid increase
in cylinder temperature &pressure.
 Piston is driven downward with great force.
 Pushing on the connecting rod & turning the
crankshaft.
 Exhaust gases are expelled then.