Douwe EgbertsEgberts CAFITESSE 300, Руководство по обслуживанию

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Spark Plugs
Chapter 3
Study Tips
How is the high voltage produced?
When does the spark discharge occur?
Basics of Ignition
Chapter 3 Basics of Ignition
35
1 High Voltage Generation
High Voltage Generation
Let us try. (2)
When the switch is switched On → Off
to cut off the primary current, the
magnetic flux generated up until now
by the primary current disappears
suddenly.
This change in the magnetic flux
generates hundreds of volts of
counter-electromotive force in the
primary coil (self-induction action) and
furthermore generates electromotive
force in the secondary coil that is
amplified by the winding ratio. (Mutual
induction action)
This is how the high voltage required
for the ignition spark is generated.
Let us try. (3)
Also when the switch is switched Off
→ On, the magnetic flux changes due
to the change in the primary coil and
the self-induction action of the coil
generates counter-electromotive force,
but this does not rise higher than the
battery voltage.
Therefore, the change in the magnetic
flux is softened and the voltage
generated in the secondary coil is so
low that it does not reach the
discharge voltage.
Let us try. (1)
If you line up the two coils and pass
current through one coil (the primary
coil), magnetic flux is generated.
When a constant current is flowing in
the primary coil, the magnetic flux
does not change, so electromotive
force is not generated in the secondary
coil.
With the coils in this state, let us try
cutting off the current in the primary
coil with the switch.
Battery Switch Primary coil
Secondary coil Voltmeter Magnetic flux
6
6
5
5
4
4
3
3
2
2
1
1
Switched on
Battery Switch Primary coil
Secondary coil Voltmeter Magnetic flux
6
6
5
5
4
4
3
3
2
2
1
1
Switched off
Switched on
1
1
4
4
3
3
2
2
5
5
6
6
1
1
4
4
3
3
2
2
5
5
6
6
Secondary
voltage
The number
of windings
in the secondary
coil.
(Counter-
electromotive
force in the
primary coil)
The number
of windings
in the primary
coil.
＝ ×
Answer: 5,8