The document discusses different types of scavenging processes used to remove burnt gases from an engine cylinder. It describes three main types: cross flow scavenging, back flow or loop scavenging, and uniflow scavenging. It also discusses detonation in IC engines, ignition and fuel injection systems, cooling systems, lubrication systems, and the effects of engine overheating.

1. Scavenging
The process of removing burnt gases from the
combustion chamber of the engine cylinder, is
known as scavenging.
Type of Scavenging:
1. Cross flow scavenging.
2. Back flow or loop scavenging.
3. Uniflow scavenging.

2. Scavenging
1. Cross flow scavenging:
The piston crown is
designed into a
particular shape, so that
the fresh charge moves
upwards and pushes
out the burnt gases in
the form of cross flow.

3. Scavenging
2. Back flow or loop
scavenging: In this
method, the inlet and
outlet ports are situated
on the same side of the
engine cylinder. The
fresh charge , while
entering into the engine
cylinder, forms a loop
and pushes out the
burnt gases.

4. Scavenging
3. Uniflow scavenging: In
this method, the fresh
charge, while entering
from one or both side
of the engine cylinder
pushes out the gases
through the exit valve
situated on the top of
the cylinder.

5. Detonation in IC Engines
The loud pulsating noise heard within the engine cylinder
is known as detonation.
Causes of detonation:
1. The shape of the combustion chamber,
2. The relative position of the sparking plugs in case of
petrol engines,
3. The chemical nature of the fuel,
4. The initial temperature and pressure of the fuel,
5. The rate of combustion of that portion of the fuel
which is the first to ignite. This portion of the fuel in
heating up, compresses the remaining unburnt fuel,
thus producing the conditions for auto-ignition to
occur.

6. Detonation in IC Engines
The detonation in Petrol engines can be suppressed
or reduced by the addition of a small amount of
ethyl fluid to the fuel. This is called doping.
Effects due to detonation:
1. A loud pulsating noise which may be
accompanied by a vibration of the engine.
2. An increase in the heat lost to surface of
combustion chamber.
3. An increase in carbon deposits.

7. Ignition Systems of Petrol Engines
Following two ignition systems of petrol engines
are important from the subject point of view:
1. Battery or Coil ignition system,
2. Magneto ignition system.

8. Magneto ignition system

9. Fuel Injection Systems for Diesel
Engines
There are two methods:
1. Air injection method,
2. Airless or solid injection method.
a. Common rail systems,
b. Individual pump system

10. Common rail systems

11. Individual pump system

12. Cooling of IC Engines
The following two systems are used for cooling
the IC engines:
1. Air cooling system
2. Water cooling system.

13. Air cooling system

14. Water cooling system

15. Water cooling system

16. Effects of Overheating
1. The overheating causes thermal stresses in the
engine parts, which may lead to their distortion.
2. It reduces the strength of the piston and may
cause even seizure of the piston.
3. It causes decomposition of the lubricating oil,
which may cause carbon deposit on the engine
and piston head.
4. It causes burning of valves and valve seats.
5. It reduces volumetric efficiency of the engine.
6. It increases tendency of the detonation.

17. Lubrication System of IC Engines
The following two lubrication systems are used:
1. Splash lubrication,
2. Forced Lubrication.
Advantages:
1. It reduces wear and tear of the moving parts.
2. It damps down the vibration of the engine.
3. It dissipates the heat generated from the moving
parts due to friction.
4. It clean the moving parts.
5. It makes the piston gas-tight.