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5-4
ELECTRONIC
IGNITION
SYSTEM
The electronic ignition system features
a
power transistor as the current control element. Therefore, the
ignition system
is
an electronic contact point-free type that operates with the power transistor impulses
4
controlling the current. This system
is
also
called TIC (transistor igniter circuit) and
is
virtually free of
ignition failure which generally results from contamination
of
the contact points, a typical problem with
contact type ignition systems.
Because this ignition system has
no
contact points, it
is
not affected by moisture,
oil,
dust, or other
contaminants.
As
a result, this electronic ignition system ensures sure and positive ignition with reduced
maintenance.
The
TIC
mechanism consists of a transistor-incorporated ignition coil and a permanent magneto built-in
flywheel which
is
press-fitted
on
the rotor shaft of the generator.
Fig.
5-9
(1)
When the permanent magneto built-in flywheel start rotating, power
is
generated in the primary coil
of the ignition coil and current flows to the resistor
@
.
From the resistor, current flows the power transistor. With this current, the power transistor turns
on,
releasing current
a.
This stage corresponds to the closing of contact points.
(2)
As
the flywheel comes to the point of ignition, timing detecting circuit
is
activated while the current
@
is flowing through the circuit.
When the ignition timing detecting circuit
is
activated, the signal transmitter transistor actuates with
current
@
flowing. When current
@
starts flowing, current
@
flowing through the power transistor
is
cut
quickly.
As
a result, high voltage is produced
in
the secondary coil and this voltage
is
applied
simultaneously to the spark plug which ignites for ignition. This stage corresponds to the opening of
contact points.
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