Today we will discuss about Magneto Ignition System. In my
last post we have learnt about Battery Ignition System its parts and working
but the Magneto ignition System is completely differ from it. Magneto is a
special type of ignition system with its own electric generator to provide
necessary energy for the ignition system. It replaces all component of battery
ignition system except spark plug. Today we will complete study about this system.
Magneto Ignition System:
Parts of Magneto Ignition System:
Magneto:
It is the major part of this type of ignition system because
it is source of energy. A magneto is a
small electric generator which is rotate by the engine and is capable of
produce a very high voltage and does not need battery as a source of external
energy. The magneto contains both primary and secondary winding thus it does
not require a separate coil to boost up the voltage required to operate the
spark plug. There are two types of magneto. First one is known as armature
rotating type and other one is known as magnet rotating type. In the first
type, the armature rotates between the stationary magnate. On the other hand in
second type armature is stationary and the magnates are rotating around
armature.
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.
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.
Working of Magneto Ignition System:
The working principle of magneto ignition system is same as
battery ignition system except in the magneto ignition system Magneto is used
to produce energy except battery. The
diagram of four cylinder magneto ignition system is as follow.
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| MAGNETO IGNITION SYSTEM |
- First when the engine starts or during cranking magneto rotate which generates a very high voltage.
- The ignition capacitor connected in parallel with contact breaker. One end of magneto winding is also grounded through contact breaker.
- The cam regulates 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 this high voltage EMF produce spark at correct spark plug through distributor.
As the engine speed is low at starting, the current
generated by the magneto is quite small. As the engine speed increases the flow
of current also increases. Thus with magneto ignition system there is always
starting problem and sometimes a separate battery needed for stating. This
ignition system is best suited at high speed so it is used in racing cars,
aircraft engines etc.
Advantages and Disadvantages:
Advantages:
1. This system is more reliable at medium and high speed.
2. It is more reliable because no battery is used.
3. It requires less frequently maintenance.
Disadvantages:
1. It has starting problem due to low cranking speed at
starting.
2. It is more expensive compare to battery ignition system.
3. There is possibility of misfire due to leakage because
wiring carry vary high voltage.
This is all about magneto ignition system parts, working,
advantage and disadvantages. If you have any query regarding this article ask
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