Electronic Ignition System:

 The ignition system of a petrol engine.

There are major changes on older generation ignition systems to modern

generation ignition systems, mechanical devices converted  Into the fully electronic system. The automobile industry has achieved drastic mechanical and technological advancement throughout history. The ignition system plays a vital role in creating combustion to run your vehicle. In modern cars, all ignition system is electronically operated by an Electronic Control Unit/Module (ECU/ECM).

What is the Purpose of the ignition system? 

In a petrol/gasoline engine the purpose of the ignition system is to ignite the compressed air-fuel mixture in the engine combustion chamber. The system provides the sparks into the spark plug through ignition coils and ignites the compressed mixture in the combustion chamber and also ensure the voltage is delivered to the correct cylinder at exactly the proper time.

After the air-fuel mixture enters the engine cylinder the piston moves up the cylinder. This compressed the trapped mixture then an electric spark at the spark plug ignites the mixture. The resulting combustion produces the power to move the car. These are methods of ignition in the engine that takes place using an electric spark in the petrol (gasoline) engine that why is called spark ignition (SI) engine

There are three types of ignition systems used in SI engines are:

• Distributor based ignition system. 

• Distributorless ignition system (DIS) / Distributorless Direct Ignition.

• Coil-On-Plug (COP) ignition system / Multiple-coil Direct Ignition.

 

Distributor Based Ignition System

Generally, the distributor based ignition system are two categories; 

Contact-breaker (CB-point) distributor based ignition system. It was the earlier design that used a fully mechanical distributor ignition system. Contact breaker (CB) point distributor based ignition system. It has a single terminal ignition coil which supplied secondary voltage to the distributor then the ignition distributor passed high tension current through plug cable or wire into the spark plugs on each combustion chamber in the petrol engines. It consists of an ignition switch, contact breaker (CB-point), condenser, high tension cable/wire, ignition coil, battery and sparkplugs. In the Contact breaker (CB-point) movable point in the distributor open and the ignition primary circuit. Circuit breaker for interrupting an electrical circuit. The distributor distributes high tension current to the engine spark plug according to firing order. Spark plug containing centre electrode for carrying high tension current from the distributor and to provide the spark in the engine combustion. The system provides high electric voltage and distributes it to individual cylinders.

It takes the electrical voltage from the battery, converts it to a much higher voltage with an ignition coil, the coil has two winding primary and secondary. The ignition coil acts as an electrical power transformed. An electric current of low voltage gets from the battery (12 Volt), that converted by the system to a high voltage of 25,000 volts. Then distributes the high tension current through the cable into the spark plug central electoral gap and ignite the mixture. The producer of the function is done mechanically. This is an earlier design CB distributor ignition system used on the petrol engine.

Next, this ignition system is similar in operation and construction to CB point distributor based ignition system, but It is operated by an electronic control unit (ECU/ECM). This is a more reliable distributor, it has breaker less or contactless means there is no contact breaker point ignition system with distributor assembly, instead of a contact breaker, there are reluctor, electronic transistor (pick up coil), ignition resistor and ignition module, ignition switch, ignition coil, This  

Semiconductor devices act as an electronic switch that turns the coil primary current ON and OFF. 

The major difference is the use of an electronic switch instead of a mechanical switch to control the primary current. In this distributor uses reluctor and pick up coil instead of CB- point, the reluctor has multiple of teeth or tip as there cylinder in the engine. When the reluctor rotates each tooth creates a voltage pulse in the pick-up coil. This signals the ignition to open the primary circuit. The distributor distributes high voltage electricity from the secondary ignition coil to each spark plug. The ignition module has an electronic control unit that opens and closes the primary circuit on the monitors of ECM. This system ignition timing is more accurate and has a simpler design delivering spark in the engine combustion chamber at the proper time relative to piston position. So that it is also considered a semi-electronic ignition system.

Electronic Ignition System

In modern vehicles, spark ignition (SI) engines using an electronic ignition system except for the contact breaker (CB) point it was older designed to operate mechanically. In action, the electronic system is much faster than the CB-point ignition system. The primary circuit is opened and closed by electronic control module/unit (ECM/ECU). Voltages stepped up is very high it produced up to near 50,000 Volts. The engine can run leaner air-fuel mixtures, this will result in better fuel economy and emission gases that will be lower. 

The advantage of Electronic Ignition System:

• increases fuel economy and more engine efficiency.

• Precise spark timing according to firing order. 

• less moving parts and components as compared to older designs ignition system.

• it compact and less frequent repairs.

Disadvantages only more expensive and 

difficult to troubleshoot because no chance to manually detect the required scan tools, because of fully operates by the electronic control unit /module.

Distributorless Ignition System (DIS)

Distributorless Ignition System (DIS), it more reliable and fully operates by the electronic ignition system, without a distributor, There are no breaker less or contactless devices and no moving parts and gear. Sometimes it is called distributor direct ignition. It bypassed the ignition distributor using a compact two coil pack in the single ignition coil unit, which means that has two ignition coil assemblies It is mounted on the side of the cylinder head of the engine. This one coil pack uses for cylinders NO.1 & NO.4 or (1&4 spark plugs), and the second coil pack uses for cylinders NO.2 & NO.3  or (2&3 spark plug), this is an example of a four-cylinder engine. Similar use another multiple cylinder engine.

When an ignition signal is sent from Electronic Control Unit (ECU) to the ignitor in the ignition coil assembly for NO.1&4 spark plug a high voltage is induced in the secondary coil and that passes through the high tension cords and cause NO.1&4 spark plug to spark simultaneously. Likewise when an ignition signal is sent to the ignitor in the other ignition coil assembly cylinder NO. 2&3 spark simultaneously. 

The several input devices sensor feeds the data to the Electronic control unit/module (ECU/ECM). Resulting in accurate ignition timing and more engine efficiency and provides better fuel economy as well as lower emissions.

The system relies on a crankshaft position sensor that relays the engine position of the ECU which then tells the coil pack when to fire the spark plug. This result in much great accuracy of the ignition timing. Another key benefit is that inside a coil there are multiple coils and a single ignition coil always handles any two cylinders. This means that unlike the distributor the wasted spark coil packs much fire any once every single revolution of the crankshaft,  regardless of the number of the cylinder of the engine. This means more voltage and better operation at the rpm ( revolution per minute).

Coil-On-Plug (COP) Ignition System / Direct Multiple Coil Ignition.

 

 Today Modern vehicles in petrol engines have this most sophisticated fully electronic direct ignition system using laterally on car segments vehicles. This system is also one form of distributor less ignition system. This same direct ignition system has different names called by different automakers. Some are prompted by the Multiple coils Direct Ignition System. But most popular is called by Coil-On-Plug (COP) Ignition System.

Coil-On-Plug (COP), completely removes the spark plugs cables as a service item and given every cylinder its each ignition coil. This means a coil on the plug or direct ignition system. They mounted a coil directly on each spark plug. The Operation is the same as the other form distributor less ignition system. This system gives each cylinder for individual ignition control module and using moulded one-piece secondary conductor to replace the spark plug cables. It enables the ECU/ECM to adjust ignition timing individually for every cylinder.  Spark plug cables s/wires to cause some voltage loss without cables full secondary voltage reached the spark plugs. This resulting in more power, less emission better mileage and provides better engine performance as well as smoother idle. Eliminating the cable also reduce maintenance. There are no cables to check and replace. 

In this system fire only once every two revolutions of the crankshaft, which means even more voltage and even better operation at high rpm (revolution per minute) and greater power. This system controls spark timing using controlled by ECU/ECM based on several sensors, like the camshaft position sensor, crankshaft position sensor, Throttle position sensor, Manifold absolute pressure (MAP) sensor and other sensors/switches using the signals from the sensor ECM/ECU identifies the specific cylinder whose piston in the compression stroke and detect the crank angle then ECU / ECM command on the to the actuator or output devices send signals to the ignitor (power unit) in the ignition coil assemblies. These consistently deliver nearly 47,000 Volts in all conditions and can handle any amount of rpm ( revolution per minute) or boost you throw your car.  A Coil-on-plug system is a powerful and versatile ignition system rest of other ignition systems. Nowadays in all modern cars using coil-on-plug (COP) or multiple-coil direct ignition systems. 

The main two categories of failure of electronic ignition system :

• Loss of energy in the secondary circuit.

• Out of time.