What Is Spark Plug?
The spark plug is one of the main parts of the engine that is provided at the top of the cylinder; without spark plugs, petrol engines do not ignite the air-fuel mixture that is supplied to the cylinder. With the help of spark plugs, a high voltage can be generated in the cylinder and makes the fuel burn.
A spark plug must be made with strong material and high-temperature resistance. It is also acting as an airtight fitting on the cylinder, which does not allow air fuel to escape from the cylinder.
The spark plug is a device used to ignite the air-fuel mixture in the engine cylinder. They are generally used in petrol engines. For fuel combustion, we need a spark to start the combustion process in a petrol engine.
Main Parts of a Spark Plug:
The main parts of the sparks plug are:-
This is the part that attaches to the high tension cable coming from the distributor cap. It conducts a high voltage to the central electrode.
It is made of aluminum oxide ceramic and acts as an insulator. It separates the central electrode from the earth by 40000 volts. It can be manufactured in plains form or with profiles to prevent flash.
#3. Metal Body
It is a steel shell manufactured with precision rolled threads for a secure fit and easy installation and removal. This provides electrical ground to the cylinder head and helps to cool the plug by transferring heat to the cylinder head.
#4. Central Electrode
It is made of nickel-based alloys, to which a copper core is attached. Depending on the type, the central electrode may be in platinum or iridium. A high voltage from the secondary winding through the distributor is applied to the central electrode.
#5. Ground Electrodes
It is a welder to the metal body of SP. This forms a spark path along the central electrode. It is made of nickel-based alloys (or iridium or titanium reinforcement).
#6. Seal Washer / Gasket
It works along with the head of the cylinder and helps in heat dissipation.
#7. Insulator Tip
It is expanded into the combustion chamber. This has a greater effect on the thermal rating of the spark plug.
#8. Electrode Gap
These are the distances between the central electrode & the ground electrode. Electrodes have an important role in spark generation. If the plug is not provided with a proper gap, it may not generate enough spark to ignite the fuel and may misfire.
The shell is almost always plated. This increases durability and provides for corrosion and corrosion resistance. The steel shell is unrealistic for a particular cold extrusion method or unreal tolerance for employment in various specific cases, machined from steel billet. The polygons created on the shell allow you to use a spanner to plug in or take away.
Spark plug threads are usually rolled, not cut. It meets the specifications set by SAE with the International Standards Association.
#11. Spark Park Electrode Gap
The area between the ground electrode & the center electrodes is called a gap. The center electrode must be manufactured from a special alloy that is resistant to both spark erosion and chemical corrosion.
These materials are achievable in a large variety of nose shapes and sizes, but in essence, the insulator nose must be able to accumulate carbon, oil, and fuel at low speeds. At high engine speeds, the insulator nose is usually cooled so that the temperature and electrode corrosion is reduced.
Insulator ribs provide additional protection against secondary voltages or spark arcs, and the rubber electrical device against the plug body at the joint facilitates boosting the grip of the boot.
The insulator body is molded with aluminum oxide ceramic. For the manufacture of this part of the electrical equipment, an aggressive, dry molding system is employed. After the insulator is molded, it is kept at a kiln temperature that is higher than the melting point of the steel.
This process results in a component with exceptional dielectric strength, high thermal conductivity, and excellent resistance to shock.
Functions of Spark Plugs:
Internal combustion engines in spark plugs have two major functions, including: Igniting Fuel / Air Mixtures: As electricals energy is transmitted through the component, it ignites the gasoline/air mixture in the combustion chamber. Another discovered function of the spark plug is in the direct ignition of the Saab.
When they are not firing, the devices are used to measure ionization in the cylinder. This ionic currents measurement is used to replace ordinary cam phase sensors, knock sensors, and misfire measurement functions. Other great purposes of spark plug include furnaces that must have a combustible fuel/air mixture ignited.
In thises case, they are referred to as flame burners. Removing heat: Spark plugs cannot generate heat, but they can only be used to dissipate heat. The temperatures of the end of the plug firing end must be low enough to prevent pre-ignition but high enough to prevent fouling.
The spark plug can act as a heat exchanger by destroying unwanted thermal energy from the combustion chamber. The heat is then transferred to the cooling system of the engine.
Working Principle of Spark Plug:
The electrical device is connected to a high voltage supply like a generator or induction coil. The other end with two electrodes is immersed in the combustion chamber. When the current passes into the terminal and main center electrode, a potential difference voltage drop is created between the two electrodes.
The gas mixture that surrounds the gap between them acts as an insulator, and thus electricity does not flow from the tip of the center electrode. But as the voltage increases, the gases in the gap begin to activate.
Once the voltage is increased, the gases exceed the dielectric strength (resistance to electricity), they are ionized. Once the gases are ionized, they begin to act as conductors and allow the current to travel through the insulating gap.
When the dielectric strength is exceeded, the electrons begin to move through that gap. This sudden movement of electrons causes a rapid increase in heat in the region that causes them to expand rapidly, causing a small explosion resulting in a spark.
Types of Spark Plugs:
There are two types of spark plugs, depending on the operating temperature relative to the tip of the high-tension electrode.
#1. Hot Spark Plug
This type of sparks plug has a heat transfer path and a large area exposed to combustion gases. This transfers heat at a very slow rate, which keeps the firing tip warm.
#2. Cold Spark Plug
It has short heat transfer paths and small areas exposed to combustion gases. It rapidly transfers heat from the firing tip to the engine head, thus keeping the firing tip cool.
Symptoms of Failing Spark Plug:
Below are signs of malfunction or failure of spark plugs and their prevention:-
#1. Slow Acceleration
When the spark plugs start to fail, you see poor acceleration on your car; however, in modern vehicles where the sensor engine is telling the highest status of the ignition system. The issue can be easily noted.
Sometimes problems may be caused by a faulty sensor, but in most cases, it is a worn-out plug. Many factors in the engine can be slow acceleration due to poor fuel filters, dirty or clogged fuel injectors, or faulty oxygen sensors. This is why a specialist needs to check the situation as soon as it starts.
#2. Bad fuel Economy
A bad spark plug can cost you more money on fuels. A good spark plug helps to burn fuels efficiently in the combustion cycle, which helps to achieve a higher than average fuel economy. Problems on spark plugs either occur because the difference between the electrodes is either too close or the difference between them.
In most cases, the mechanics adjust the gap when you complain of a similar problem. Well, it is better to changes the plug to avoid such in the future.
#3. Difficult Startup
When you find a DIY driver losing his or her spark plugs, the problem is common when he has trouble starting his car. Most of the time, this equipment goes bad. But, various symptoms can affect the engine’s ignition system, a specialist should be included.
#4. Engine Misfiring
The missing engine is a problem with the ignition system; in modern cars, it is often a sensor fault. But it is also caused by the spark plug wire or if the tip of the spark plug that connects the wire has been damaged. If an engine misfires, the driver will experience intermittent or loud noises in the engine.
If care is not taken and misfiring continues, emissions will increase, fuel economy will decline, and engine power will decrease. So, a different problem is related to misfire, considering a mechanic immediately consider that you see a misfire in the engine.