All About Spark Plugs — Carengineered.com
The Engines we rev produces a high amount of power and forms an integral part of any automobile. The Engine combined with a number of subsystems makes it possible for and automobile to work properly.
Ignition System is one of the most important subsystems for any automobile without which the engine won’t even start.
The main components of an ignition system are as follows:-
Today we shall discuss the Spark Plugs, their design, and functioning.
Spark Plugs in SI Engines
Spark Plugs ( In British English called Sparking Plug ) as the name describes are the plugs that have some connection with a spark.
These Spark Plugs are the electrical component that initiates a spark whose magnitude it so high to initiate the combustion process.
In SI Engines the air-fuel mixture after mixing enters the combustion chamber or the cylinder.
This air-fuel mixture also called a charge are then compressed by the reciprocating motion of the piston inside the air sealed cylinder that increases the temperature and the pressure of the charge.
The Spark Plugs that are perfectly timed generated the spark at the perfect time with a precise flow that initiates the combustion process and hence the power is generated.
Do CI Engines have Spark Plugs??
On the other hand in CI Engines the charge is only the air and after compressing the air the fuel is injected that initiates the combustion process and power is produced.
This is the reason that Spark Plugs are not employed in the Compression Ignition System.
Construction of a Spark Plug
A spark plug consists of a metal threaded shell, that is electrically isolated from the central electrode by a porcelain insulator.
This central electrode, which may contain a resistor, is connected by a heavily insulated wire to the output terminal of an ignition coil or a magneto.
The spark plug’s metal shell is screwed to the engine’s cylinder head and thus electrically grounded
The central electrode protrudes through the porcelain insulator into the combustion chamber, forming one or more spark gaps between the inner end of the central electrode and usually one or more protuberances or structures attached to the inner end of the threaded shell and designated the side, earth, or ground electrode(s).
Parts of a Spark Plug
Insulator — The insulator Insulates the terminal, the center shaft, and the center electrode from the housing, preventing the escape of a high voltage from the electrodes.
Since the bottom part of the insulator protrudes into the combustion chamber, high purity alumina with a superior heat-proof characteristic, mechanical strength, excellent insulation, and thermal conductivity at high temperature is used.
Terminal
The terminal is connected to a high-tension cord through which high-voltage current from the ignition system (distributor) flows.
A terminal nut is also installed so this type can support almost all high-tension cord around the world.
Packing washer or the Ring
Ensures the insulator and the housing fit tightly to with others and maintains the airtightness.
Stem ( Center Shaft )
Center shaft connects the terminal and center electrodes.
This shaft is made up of steel and has the role of allowing high-voltage current to flow from the terminal to the center electrode without the loss.
Housing
The housing forms an outermost shell surrounding the insulator also supports the insulator and installs the spark plug in the engine.
To the bottom side, the ground electrode is located, so current can flow through the engine itself to the center electrode over the gap.
Glass Seal
Situated between the central shaft and the insulator to maintain the airtightness.
Gasket
Makes the housing and the engine fit tightly with each other and also maintains the airtightness of the combustion chamber.
Electrode with Copper
A Special type of nickel alloy is used for the center electrode to reduce electrode wear.
Copper is sealed into the center section to improve thermal conductivity.
Center Electrode
A new type of iridium alloy tip with a diameter of 0.4 mm is laser welded to the tip of the center.
U-Groove Ground Electrode
Nickel chrome is used as the material for the ground electrode and various measures are taken with the shape and design to improve the ignition performance.
Tapered — Cut Ground Electrode
The ground electrode has a shape in which the electrode tip is cut to a very fined tapered shape.
This reduces the quenching effect, so as to improve the ignition performance.
What is the benefit of replacing a spark plug?
The primary benefit is that your car will start without a hitch.
Consistent production of optimal combustion — Smooth and consistent functioning spark plugs lead a smooth and consistent functioning combustion system.
Better fuel economy — According to the National Institute for Automotive Service Excellence, misfiring of the spark plugs can reduce fuel efficiency by 30%. New plugs, when replaced at particular intervals, assists in maximizing the fuel economy.
Smooth and energetic starts — Old Spark Plugs are the common reasons for the jerk start of the engine that could just go away by just replacing with the newer.
Less harmful emissions — According to the Environmental Protection Agency regular engine tune-ups and not only save gas but also reduce air pollution. That’s a win-win.
Conclusion
Thus, the Spark Plugs are most important and a lot of engineering has been done overtime to make this small piece into a sophisticated engineering masterpiece.
Originally published at https://www.carengineered.com on July 1, 2020.
