Magneto Ignition System - Parts, Working Principle, Advantages and Disadvantages with Application

A combustion engine which has some vivid characteristic like high speed and high internal compression requires a system that produces very high ignition from the spark plug which is used as the source. The ignition system is the system which uses the spark plug as their source where electrical energy is input given to the spark plug.

There are three types of ignition system
  1. Battery Ignition System
  2. Magneto Ignition System
  3. Electronic Ignition System
The Magneto Ignition System is a unique kind of Ignition System which has its own source to generate the necessary amount of energy for an automobile or a vehicle to work.

Main Parts

Magneto Ignition System


Here is the list of parts that are used in it
  1. Magneto
  2. Distributor
  3. Spark Plug
  4. Capacitor

1. MAGNETO

The source that generates energy in the Magneto Ignition System is the Magneto. Generally, a magneto is a small generator that works on electricity. When magneto is rotated by the engine, it produces the voltage. The higher the rotation, the greater will be the amount of voltage produced by the system. The magneto does not need any external power source such as a battery to kick start it as it itself is a source for generating the energy. There are two types of winding in it. It has a primary binding and a secondary binding.

In addition to this, magneto has 3 types based on its engine rotation
  1. Armature rotating type
  2. Magnet rotating type
  3. Polar inductor type 
In the armature rotating type, armature rotates between the stationary magnet whereas in the magnet rotating type, the armature is stationary and the magnets are rotating around the armature. In the polar inductor type, both the magnet and the windings remain stationary but the voltage is generated by reversing the flux field with the help of soft iron polar projections, called inductors.

2. DISTRIBUTOR

The distributor that is used in the Magneto Ignition System is also used in the multi-cylinder engine. The multi-cylinder engine is used for regulation of spark in a correct sequence in the spark plug. The surge of the ignition is distributed uniformly among the spark plugs. There are two types of distributors
  1. Carbon brush type distributor
  2. Gap type distributor
In carbon brush type, the rotor arm sliding over the metallic segment carry the carbon brush which is embedded inside the distributor cap or molded insulating material. This help to provide an electric connection with the spark plug. In gap type, the distributor electrode of rotor arm is close to the distributor cap, but no contact is made leading no wear for the electrode.

3. SPARK PLUG

The spark plug used in the this Ignition System has two electrodes that are parted from each other. A high voltage flows through it which causes the generation of the spark and used to ignite cylinders combustion mixture like oil. The electrode used in it is a steel shell and an insulator. The central electrode is connected to the supply of ignition coil and outer steel shell which is grounded insulating both of them. There is a small air gap that is left between the central electrode and the steel shell where the spark is generated. The central electrode is close when the spark is generated and hence it is made of a high nickel alloy that can withstand high temperature and resistances.

4. CAPACITOR

The capacitor used in the Magneto Ignition System is a simple electrical capacitor in which two metal plates are separated by an insulating material with a distance. Commonly, air is used as insulating material, but for a particular technical requirement, some high-quality insulating material is used.

Working Principle Of Magneto Ignition System

The working principle of the this ignition System is similar to the working principle of coil or battery ignition system except that in it magneto is used to produce energy but not the battery. Here are the following scenarios that occur in it.
  1. When engine in the system starts it help magneto to rotate and thereby producing the energy in the form of high voltage.
  2. The one end of the magneto is grounded through contact breaker and ignition capacitor is connected to it parallel.
  3. The contact breaker is regulated by the cam and when the breaker is open, current flows through the condenser and charges it.
  4. As the condenser is acting like a charger now, the primary current flow is reduced thereby reducing the overall magnetic field generated in the system. This increases the voltage in the condenser.
  5. This increased high voltage in the condenser will act as an  EMF thereby producing the spark at the right spark plug through the distributor.
  6. At the initial stage, the speed of the engine is low and hence the voltage generated by the magneto is low but as the rotating speed of the engine increases, it also increases the voltage generated by the magneto and flow of the current is also increased. To kick start the engine, we can use an external source such as the battery to avoid the slow start of the engine. 

Advantages and Disadvantages

Advantages

  • It is more useful at medium and high speed. 
  • It is more useful because no battery is used.
  • It requires less maintenance.
The main advantage of the magneto ignition system over other ignition system is it doesn't require any external source to generate energy. It was managed at low tension and high tension. In the high tension, a huge amount of voltage is generated using a step-up transformer which can be used for engines like the airplane engine and low tension can manage this voltage letting it flow in the smallest part of the wiring and this avoid the leakage too.

Disadvantages

  • It has starting problem due to the low rotating speed at starting of the engine.
  • It is more expensive when compared to battery ignition system.
  • There is a possibility of misfire due to leakage because the variation of voltage in the wiring can occur. 

Application 

  1. Here is the partial list of the applications of engines equipped with magneto ignition system.
  2. Tractors, Oil Burners, and Outboard Motors
  3. Washing Machines
  4. Trucks and Cement Mixers 
  5. Buses 
  6. Airplane Engines
  7. Power Units, Marine Engines and Natural Gas Engines
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