5. Why is a Diesel Engine also known
as Compression-Ignition Engine?
Uses the heat of compressed air to ignite fuel which is
injected into the combustion chamber.
Compressed
Air heats the
air to 550 °C
Examples of
combustion under
compression
Compression-Ignition Engine does not
require a spark plug like a petrol engine.
6. The Internal Combustion Engine (IC
Engines)
1. Fuel and air is Burns its
mixed in the
combustion chamber
fuel inside
the engine
2. Mixture pressurizes
3. Mixture ignites and
expands
4. Forces the piston
down
5. Turns the crankshaft
that through gears
turns wheels
8. The External Combustion Engine (EC
Engines)
Fuel is burned in a
boiler and then steam
is carried out to the
engine
Steam used to force
piston down
Fuel is
burnt
outside
the engine
9. Two types of Internal Combustion
engines
Two Stroke Engine
Fuel is
burnt
inside the
Four Stroke Engine
engine
10. Four Stroke Engine
Most commonly used for automotive
and industrial purposes
The piston completes four separate strokes
This makes two separate revolutions of the
engine's crankshaft ( rotating disk). This is
connected to gears that often make wheels
turn.
The four-stroke cycle is more efficient , larger and
quieter than the two-stroke cycle, but requires more
moving parts and manufacturing expertise
11. Essential parts of 4 stroke diesel engine
Cylinder is hollow &
Combustion Chamber. Stationary
Where the air
combusts due to Piston slides up and
increased pressure down in cylinder
Piston rings provide a
Crankshaft turns the up
tight seal between the
and down motion into a
piston and cylinder
rotating motion
wall. Reduce friction
and control the
lubrication.
12. Four Stroke Engine: Intake stroke
4. Air & Fuel enters in
2. Inlet
valve open
1. Piston at top
3. Piston moves down
reducing pressure in
cylinder
13. Four Stroke Engine: Compression
Stroke
1. Inlet Valve
3. Air-Fuel mixture
closed
gets compressed.
Heats air to 550°C
2. Piston moves up
14. Four Stroke Engine: Power Stroke
1. Air-Fuel mixture
2. The burning fuel puts gets so compressed
pressure on piston, that it combusts
pushing it downwards
15. Exhaust Stroke
.
1. Exhaust valve
opens. Exhaust gas
leaves cylinder
2. This releases the
pressure so the piston
goes up
16. Four Stroke Engine
1.Intake Stroke
2. Compression Stroke
3. Power Stroke
4. Exhaust Stroke
4 strokes means 2
revolutions of the crankshaft
Video
17. Operation of a Four Stroke Engine
Strokes Movement Intake Valve Exhaust Action in
of Piston Valve combustion
chamber/
Cylinder
Intake Stroke Open Closed Fuel & air enters
chamber
Compression Closed Closed Fuel & air is
Stroke compressed
Power Stroke Closed Closed Compressed fuel
and air ignites
Exhaust Closed Open Piston pushes
Stroke exhausts out of
cylinder
18. 4 Stroke Diesel Engine
The four strokes complete the engines cycle. As soon as one
cycle is complete, the other begins
The pistons move due to momentum
But to get started they need external
energy
An electric motor or manual rotation
of the crank is needed to start the
engine
4 stroke engines have a dedicated
lubrication system
19. Two Stroke Engine
In a two stroke engine a cycle is completed in two strokes of
a piston or one complete revolution (360º) of a crankshaft.
Up Down
This is achieved by
exhausting and
recharging the cylinder
at the same time
20. Two Stroke Engine: Intake/Exhaust
Stroke
No valves for exhaust and air but holes on the side of the
cylinder wall. The piston covers and uncovers these holes.
Exhaust
Intake hole is open
and air and fuel comes
in. This forces
exhausts out
21. Two Stroke Engine: Compression
Stroke
Up
Inlet port gets closed and
Air-fuel mixture in the
Piston moves chamber starts getting
compressed.
upwards
22. Two Stroke Engine: Power Stroke
Fuel combusts
Down
The engine is lubricated using special oil
mixed with the diesel.
Piston gets
pushed down
by hot gases
This leads to
the intake and
exhaust holes
being open and
so the engine
exhausts &
recharges
23. Two Stroke Engine
Fuel combusts
Air & Fuel in
2 strokes of Exhaust out
piston
1 rotation of
crank shaft
24. Two Stroke Engine
Advantages
Simple Design
Less weight
Easier to manufacture
High power to weight ratio
Disadvantages
Do not consume fuel efficiently.
Produce more pollution.
2-stroke engines should be used for light
vehicles that are used for short periods of
time
28. Advantages of Diesel Engines against
Petrol Engines
They burn less fuel than a petrol engines performing the
same work
More efficient than petrol engines
They are more reliable as less electrical parts
Diesel engines last about twice as long as petrol
engines due to the increased strength of parts used
29. Engine Cooling Systems
Temperatures inside the engine can rise to over
4,000°F
Such a high temperature will put serious stress on
the engine’s parts
metal expands lubricant get thinner
The pistons & cylinders is subjected to extreme
stress if the heat does not escape
Overheating is one of the dangers of combustion.
When this happens, the engine can break down if it
cannot get rid of the heat that has built up in its
chambers.
32. Noise & Air Pollution
This can cause
asthma, lung
cancer, and early
death
Diesel produces carbon
dioxide, soot & nitrogen
oxides
Diesel contains impurities
that which makes acid
rain
Diesel Engines can be very noisy
and can disturb people and
animals.
33. Summary Questions
1. Why is an IC engine different from an EC
engine?
2. What is different about petrol and diesel
engines with the way they ignite fuel?
3. Where would you expect to find a 4 stroke
engine?
4. What are some of the advantages of a 2
stroke engine and when should they be
used?
5. What type of pollution do we get from
diesel engines?
34. Trouble Shooting of Diesel Engine.
Cause / Fault Remedy To Remove it.
No fuel in tank Fill tank with fresh fuel.
Water in fuel Drain the tank. Clean carburetor and fuel lines.
Fill tank with fresh and clean fuel.
Carbon in Remove the cylinder.
combustion Clean carbon from head and piston
chamber
Loose flywheel Check fly key
Tighten flywheel
Loose Replace connecting rod.
connecting Rod
35. Trouble Shooting of Diesel Engine.
Engine Overheats
Cause / Fault Remedy / To Remove it.
1 Engine improperly Time the Engine
timed
2 Carburetor Adjust Carburetor
improperly adjusted
3 Excessive load on Check operation of associated
engine equipment
Reduce excessive load.
4 Lack of Lubrication Full crankcase with proper oil.
36. Trouble Shooting of Diesel Engine
Engine Vibration (heavy)
Cause / Fault Remedy / To Remove it.
1 Engine not securely Tighten the loose mounting
mounted bolts.
2 Bent crankshaft Replace crankshaft
3 Associated equipment out Check associated equipments
of balance
