44
1
Sparking
Pattern from sparking to firing
2
Generation of flame nucleus
3 Growth of flame nucleus
4 Firing
Electric discharge
energy activates part of
mixed air and a small
flame is produced.
Sparks discharge on
the part of the electrode
where they can
discharge most easily.
The flame grows even
though energy is being
absorbed in the ground
electrode.
Growth of the live coal
accelerates and finally,
the flame spreads as
explosive combustion.
Weak
Strong
Electric field strength shown using FEM(*
1
) analysis
Strength of electric field
Why was the center electrode of the
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
the world’s
smallest(*) electrode, at 0.4 mm in diameter,
in the
.
Q
2
A
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
I
to improve
firing performance
.
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.
Normal spark plug(*
2
)
The above shows the strength of electrical field in case certain voltage changes on normal spark plug
and
.
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.
*: As of Nov. 1999, this excludes flush type electrodes that do not protrude from the insulator.
