DENSO SPARK PLUGS - Basic Knowledge

It is a question concerning the IRIDIUM POWER that is often.

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Why was the center electrode of the IRIDIUM POWER reduced to only 0.4 mm?

To lower the required voltage and improve firing performance. The most advanced technology in the world has been employed to enable use of electrode, at 0.4 mm in diameter, in the IRIDIUM POWER.

The smaller the electrode the more concentrated the electric potential at the tip of the electrode and the stronger the electric field that affects required voltage and the lower the required voltage. As a result, combustion is good for all types of driving, the engine starts easily, and acceleration improves.

The above shows the strength of electrical field in case certain voltage changes on normal spark plug and IRIDIUM POWER.
The more electrical field strength is getting high, the more it becomes easy to fire with low voltage.
*1 FEM(Finite Element Method analysis): General method to measure electrical field strength.
*2 Normal spark plug mentioned in this brochure is resistor plug.

The electrode also has a quenching (cooling) effect (effect where the electrode takes away the heat of the spark as soon as firing occurs). Therefore, in a thick electrode the cooling effect is great and sometimes firing does not occur as shown in Figure 4 . The characteristics of this firing is called firing performance. To improve firing performance, the contact area between the electrode and the flame nucleus needs to be made reduced in size.
Accordingly, the electrode was made as fine as possible in the IRIDIUM POWER to improve firing performance.

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