Today we will discuss about battery ignition system main
parts, function, working, advantages and Disadvantages. Most of SI engine used
battery ignition system. In this system a 6 volt or 12 volt battery used to
produce spark. Passenger cars, light truck, motorcycles and large stationary
engines are fitted with this system.
Battery ignition system:
Main Parts of battery ignition system:
Battery
A battery is used to provide energy for ignition. It is work as storage of
energy and charged by dynamo, which is driven by engine. It converts chemical
energy to electric energy. Two types of battery used in spark ignition system,
lead acid battery and alkaline battery. The first one is used in light duty
commercial vehicle and the other one is used in heavy duty commercial vehicle.
It is housed in primary side of ignition coil.
Ignition switch
It is used to turn on and off the ignition system. Battery is connected to the
primary winding of ignition coil by ignition switch and ballast resistor.
Ballast resistor
It is connected in series with primary winding to regulate current in primary
winding. It is used to prevent injury due to overheating of ignition coil. It controls
the current passes through primary winding. It is made by iron. Iron has property
of increase electrical resistance rapidly by increase in temperature at certain
limit. This additional resistance resists flowing current which control the
temperature of ignition coil.
Ignition coil
Ignition coil is the main body of battery ignition system. The purpose of
ignition coil to step up the battery voltage (6 or 12) to a high voltage, which
is sufficient to produce spark at spark plug. It consist a magnetic core or
soft wire or sheet, and two electrical winding called primary winding and
secondary winding. The primary winding has generally 200-300 turn and the end
are connected to exterior terminal. The secondary has almost 21000 turns of
copper wire which is insulated to withstand with high voltage. It is located
inside the primary winding and its one end connected to secondary winding and
other end is grounded either to primary winding or to the metal case. This
entire unit is enclosed in a metal container which makes it a compact unit.
Contact breaker
This is a mechanical device making and braking the primary circuit to ignition
coil. When the points are closed current flow in ignition coil and when it
open, flow of current stopped.
Capacitor
It is a simple electrical capacitor in which two metal plate are separated by
an insulating material with a distance. Commonly air is used as insulating
material but for particular technical requirement some high quality insulating
material is used.
Distributor
Distributor is used in multi cylinder engine to regulate spark in each spark
plug at correct sequence. It distribute ignition surge in individual spark plug
in correct sequence. There are two types of distributor. One is known as carbon
brush type and the other one is gap type. In carbon brush type carbon brush
carried by the rotor arm sliding over the metallic segment embedded into the
distributor cap or molded insulating material. This makes electric connection
or secondary winding with spark plug. In gap type distributor electrode of
rotor arm pass close to but does not make contact with the distributor cap. So
there is no wear of electrode.
Spark Plug
A spark plug generally has two electrodes which are separated with each other.
A high potential discharge flow through it which generate spark and ignite the
combustion mixture in cylinder. It mainly consist two electrodes a steel shell
and an insulator. The central electrode connected with the supply of ignition
coil. It is well insulated with the outer steel shell which is grounded. There
is a small air gap between steel shell and central electrode, between which
spark is generated. The electrode usually made by high nickel alloy so it can
withstand with high temperature and corrosion resistance.
Working of Battery Ignition System:
In the battery ignition system ignition coil stores the
energy in form of magnetic field and deliver it at the instant of ignition, in
form of high voltage current with high tension wire to correct spark plug. The
diagram of four cylinder battery ignition system is as follow.
- First low voltage current flow form battery to the primary coil through ignition switch and ballast resistor.
- Ballast resistor regulates the temperature of ignition coil by regulating current passing form it.
- The ignition capacitor connected in parallel with contact breaker. One end of secondary winding is also grounded through contact breaker.
- When the ignition switch is closed, the primary winding of the coil is connected to the positive terminal, and current flow through it known as primary current.
- The current flows form primary coil produces a magnetic field which induces an EMF in secondary coil.
- The cam regulate the contact breaker. Wherever the breaker open, current flows into condenser, which charged the condenser.
- As the condenser become charger the primary current falls and the magnetic field collapses. This will induces a much higher voltage in condenser.
- Now the condenser discharge into the battery which reverse the direction of both primary current and magnetic field. This will induce a very high EMF in secondary winding.
- Now this high voltage EMF produce spark at correct spark plug through distributor.
Advantages and Disadvantages:
Advantages:
1. At the time of starting or at low speed good spark is available.
2. The battery which is used to generate spark can be used to
light other auxiliary like headlight, tell light etc.
3. Initial expenditure is less and
it has low maintenance cost.
4. Ignition system is not affected by
adjusting spark timing in battery ignition system.
Disadvantages:
1. Time available of built up the current and stored energy is
decrease as speed of engine increases.
2. Contact breaker subjected to both electrical and mechanical
wear which results short maintenance interval.
3. The primary voltage decreases as the engine speed increase.
So it is not fully reliable of high speed engine.
It is all about battery ignition system parts, principle,
working, advantages and disadvantages. If you have any query regarding this
article, ask by commenting. If you like this article doesn’t forget to share it
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