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2. Ignition system
 An ignition system is a system for
igniting a fuel-air mixture. Ignition
systems are well known in the field of
internal combustion engines such as
those used in petrol (gasoline)
engines used to power the majority of
motor vehicles.

3. Functions of ignition system
•Provides a method of turning a spark ignition
engine on & off.
•Operates on various supply voltages (Battery &
Alternator)
•Produces high voltage arcs at the spark plug
electrode.
•Distributes spark to each plug in correct
sequence.
•Times the spark so that it occurs as the piston
nears the TDC on the
compression stroke.
•Varies the ignition timing as engine speed, load
and other conditions

4. Requirements
•To make a spark inside the engines cylinders
which is strong enough to ignite the air/fuel
mixture. In normal atmospheric conditions only
about 600 Volts are needed to make a spark,
however in the pressurised environment of the
engines cylinders, 8000 to 30,000 volts will be
required.
•To ensure the spark happens at the right time for
each cylinder going through the 4 Stroke Cycle i.e.
just at the end of the compression stroke. The
ignition system also has to change the time at
which the spark occurs (the ignition timing)
depending on engine operating conditions e.g.
how fast the engine is turning.

5. Factors consider for design
ignition system
 Combustion chamber design
Air-fuel ratio
Engine speed range
Engine load
Engine combustion temperature
Emission regulation

6. Types of ignition system
Mechanical ignition system
Electronic ignition system
Distributor-less ignition system

8. Ignition Parts System
BATTERY provides power for system.
IGNITION SWITCH allows driver to turn ignition on and off.
IGNITION COIL changes battery voltage to 30,000V during
normal operation and has a potential to produce up to 60,000V.
SWITCHING DEVICE mechanical or electronic switch that operates
Ignition coil(Pick-up coil, Crank sensor, Cam sensor).
SPARK PLUG uses high voltage from ignition coil to produce an arc
in the combustion chamber.
IGNITION SYSTEM WIRES connect components.

9. Ignition Circuits
PRIMARY CIRCUIT
•Includes all the components
working on low voltage
(Battery, Alternator).
SECONDARY CIRCUIT
•Consists of wires and points
between coil out-put and the
spark plug ground.

10. Ignition Coil
Primary Windings are made up of several
hundred turns of heavy wire wrapped around
or near the secondary windings.
Secondary Windings consist of several thousand
turns of very fine wire, located inside or near
the secondary windings.

11. Distributor
•Actuates the on/off cycle of current flow through the ignition coil
primary windings.
•It distributes the coils high voltage to the plugs wires.

12. Distributor
•It causes the spark to occur at each plug earlier in the compression
stroke as engine speed increases, and vice versa.
•Changes spark timing.
•Some distributor shafts operate the oil pump.

14. Advantages of electronic ignition
system
• Moving parts are absent so no maintenance are
required.
• Contact breaker point are absent so no arcing.
• Spark plug life increase by 50% & they can be use
above 60000km without any problem.
• More power output.
• More fuel efficiency.
• Better combustion in combustion chamber about 90
to95% of air-fuel mixture. Is burn compared with 70-
75% with conventional

15. Types of Electronic Ignition
System
Capacitive discharge ignition
system
Transistorized system
Piezo –electric ignition system
Texaco ignition system

16. Capacitive discharge ignition
system
 Capacitor discharge ignition (CDI) or thyristor
ignition is a type of automotive electronic ignition
system which is widely used in outboard motors,
motorcycles, lawn mowers, chainsaws, small
engines, turbine-powered aircraft, and some
cars.
 It was originally developed to overcome the long
charging times associated with high inductance
coils used in inductive discharge ignition (IDI)
systems, making the ignition system more
suitable for high engine speeds (for small
engines, racing engines and rotary engines).
The capacitive-discharge ignition uses capacitor
discharge current output to fire the spark plugs.

17. Basic principle
 Most ignition systems used in cars are inductive
discharge ignition (IDI) systems, which are solely
relying on the electric inductance at the coil to
produce high-voltage electricity to the spark plugs
as the magnetic field collapses when the current to
the primary coil winding is disconnected (disruptive
discharge).
 In a CDI system, a charging circuit charges a high
voltage capacitor, and at the instant of ignition the
system stops charging the capacitor, allowing the
capacitor to discharge its output to the ignition coil
before reaching the spark plug.

18. Capacitive discharge ignition
system

19. •A CDI system has a short charging time, a fast
voltage rise (between 3 ~ 10 kV/μs) compared to
typical inductive systems (300 ~ 500 V/μs) and a
short spark duration limited to about 50-80 µs.
•The fast voltage rise makes CDI systems
insensitive to shunt resistance, but the limited
spark duration can for some applications be too
short to provide reliable ignition.
•The insensitivity to shunt resistance and the
ability to fire multiple sparks can provide improved
cold starting ability.
Advantage and disadvantage

20. • Since the CDI system only provides a
short spark, it's also possible to combine
this ignition system with ionization
measurement.
• This is done by connecting a low voltage
(about 80 V) to the spark plug, except
when fired.
• The current flow over the spark plug can
then be used to calculate the temperature
and pressure inside the cylinder.

21. Piezo-electric ignition system
APPLICATION :
 Camping stoves
 Gas grills
 Lighters
 Potato guns

22. •It consist small spring loaded hammer when
a button is pressed , hit a quartz crystal
This sudden deformation produce a high
voltage & subsequence electrical discharge
when ignite the gas.
No external electric connection is required .
Sometimes wire are used to locate the
sparking location away from the crystal.

23. •Piezo-ignition system can be operated by
lever push button , only one electric spark
generated when pressed the button.
The development of synthetic piezo electric
material produce in above 22kW by
mechanical loading of a small crystal
resulted in some ignition system for single
cylinder engine , but due to difficulties of
high mechanical loading timely control &
ability to produce sufficient voltage.

24. Transistorized system
Emitter
Base
Collector

25. Block diagram

26.  The electronic ignition system employed a
solid state electronic device made for
semi conductor transistor & thyristor are
such type of device that are
without opening & closing the contact .
The tiny size behaves as a relay and can
operates as a switch also at speed must
higher than those required.
 Transistor is a two junction construction &
thyristor is a three junction construction.

27.  Both are made for N – type and P – type
semi conductor.
 In N-type the conductor take place
through electrons and P-type in hole
which are the vacuum size of the electron.
 They are basically made from silicon ,
germanium elements . After that doping
with aluminum , antimony , phosphorus ,
indium etc.

30. The Texaco Ignition System
•The Texaco Ignition System (TTIS) is a high frequency
system with a bi-directional spark current, the duration of
which is a function of crankshaft rotation rather than time.
The spark current characteristics differ drastically from
those of conventional discharge systems and, as a result,
current flow through the plug gap can be maintained under
extremely turbulent conditions.
•Being essentially a constant current device, it prevents
excessive plug current flow during initial gap ionization,
providing a good plug life; yet it has high average current
to increase fuel ignition probability.
•TTIS is of solid state design, and both the spark timing
and spark duration are controlled by use of digital logic
circuitry.