9M405.8.ppt D GRSGSJG s"DGJ ASRGJAS RG ASRG R

SCV EWGE HWAEGH' BRW GV FSVV

1. 1
Recap
In previous period we learnt about
•Cooling systems of I.C engines
•Air cooling
•Water cooling
•Comparison of air cooling and water
cooling systems

2. 22
Objectives
On completion of this period, you would be able to
• Know the working of a battery coil ignition system

with a neat sketch.
• Know the working of magneto ignition system with

neat sketch.

3. 3
Types of Ignition System
There are mainly two types
1) Coil Ignition system or Batter Ignition
system
2) Magneto Ignition system

4. 4
Battery Coil Ignition System
Fig 1

5. 5
Battery Ignition System
The main parts are
1)Battery: supplies current at low voltage(6-
10Volts)
2)Ignition coil: transforms the battery voltage
from 12V to 10000V to produce spark at the
spark plug
3)Contact breaker:
I.it breaks low voltage current and causes the coil to
produce a high voltage current.
II.it controls the timing of spark .

6. 6
•Capacitor:
–Connected in parallel with contact breaker unit.
– It protects the contact points from pitting
•Distributor :
–fitted to multi cylinder engines ,
–it distributes high voltage current to the appropriate
spark plug
Battery Ignition System

7. 7
It consists two circuits:
• Primary circuit : Consists of
•Battery
•Ignition switch
•Ammeter
•Primary coil
•Contact breaker
•Capacitor (Condenser)
Battery Ignition System

8. 8
Secondary circuit : It consists of

• Secondary coil
• Distributor
• Spark plugs
Battery Ignition System

9. 9
Battery Ignition System

10. 10
Battery Ignition System
Working:
•When the Ignition Switch is closed the current starts
flowing from battery through the primary circuit and
develops magnetic field in a core of the coil.
•When the breaker points are opened by the action of
cam, the magnetic field collapses.

11. 11
•This varying flux produces high voltage in secondary
circuit which is fed to contact points of distributor.
•This high voltage current produces a spark by
jumping across an air gap provide between the
electrodes of spark plug.
Battery Ignition System
Working (contd..):

12. 12
Ignition system
Firing order :
• it is the sequence in which the fuel is ignited
in the cylinders of a multi cylinder engine
• It is adopted to reduce vibrations.
for 4- cylinder engine
1-3-4-2 or 1-3-2-4
for 6- cylinder engine
1-4-2-6-3-5 or 1-2-4-6-5-3

13. 13
Magneto Ignitions System
Fig 2

14. 14
Magneto Ignition System
•This system consists of
a) Magnet b) Ignition switchc) Breaker
points
d) Condenser e) Distributorf) Spark
plug
•It has stationary coil, which carries primary &
secondary windings
•As the magnet turns i.e., magnetic field produced
and it varies from a positive maximum to a negative
maximum and back again
•The high voltage is induced in the Secondary
winding with the help of breaker points and
condenser

15. 15
Magneto Ignition System
•When the breaker points are opened by the Cam,
the condenser is charged
•The rapid discharge of condenser causes very
rapid break down of magnetic flux
•This induces very high voltage in the secondary
winding, which is led to spark plug by the distributor
•This system is used in racing cars, scooters and
motor cycles

16. 16
Summary
We have discussed about
•The working of a battery coil ignition system with a
neat sketch
•The working of magneto ignition system with neat
sketch
16

17. 17
QUIZ
1)In coil ignition system, the voltage required to produce a
spark across the gap, between the sparking points is
(a) 5000 to 10000 volts
(b) 10000 to 20000 volts
(c) 25000 to 30000 volts
(d) none of the above.
17

18. 18
QUIZ
2) The magneto ignition system is generally employed in
(a) scooters
(b) buses
(c) cars
(d) none of the above