Spark Plugs
Chapter 2 Spark Plugs
10
1
1
2
2
3
3
4
4
5
5
1
2
3
4
−
10kV
〜
30kV
V
a
b
c
d
e
T
−300V
Change in the required voltage
The ignition system normally generates 10-30 kV secondary voltage.
1
.
When the primary
current is cut off at the 'a'
point, the secondary
voltage rises.
2
.
At the 'b' point,
partway through the rise
in voltage, the spark plug
reaches the required
voltage and a spark is
generated between the
electrodes.
3
.
Between 'b' and 'c' is
called the capacitance
spark. At the start of the
discharge, the spark is
generated by the
electrical energy stored in
the secondary circuit.
The current is large but
the duration is short.
4
.
Between 'c' and 'd' is
called the inductance
spark. The spark is
generated by the
electromagnetic energy
of the coil. The current is
small but the duration is
long. From the 'c' point,
the discharge is
continued for about 1
millisecond and at the 'd'
point, the discharge
ends.
Voltage rise
Spark generation
Capacitance spark
Inductance spark
About 1 millisecond V: Voltage T: Time
5
5
4
4
3
3
2
2
1
1
