6.
MAGNETO
6-
1
Flywheel
Magneto
The ignition system
of
the
EH30/EH34.
and
EH43
is pointless flywheel magneto with automatic
advancing characteristic.
Being different from the breaker point
type
ignition system, this system
is
completely free from
such troubles as starting-up failure owing to dirty, burnt
or
corroded point surface. The electronic
automatic advancing ensures extremely easy starts and stable high performance at operating speed
by
advancing the ignition timing to the most suitable point.
6-2
BASIC THEORY
(1)
Revolution of the flywheel generates electricity on the primary side of the ignition coil, and
the base current
I1
flows to the power transistor.
Current
I1
turns the power transistor
"ON"
and the electric current
Iz
flows.
Resister
Ignition Coil
Fig.
66
(2)
At lower engine revolution, when the flywheel reached the ignition point the low speed ignition
timing controll circuit operates to run the base current
I3
to turn the signal transistor
A
"ON"
allowing the current
I1
to bypass as current
14.
At this moment the power trausistor turns
"OFF"
and the current
I2
is
abruptoy shut resulting
in the high voltage generated in the secondary coil which produces sparks
at
the spark plug.
(3)
At higher engine revolution, the advancing controll circuit operates
at
the ignition timing to
run the base current
15
to turn the signal transistor
B
"ON
allowing the current
I1
to bypass
as current
Is.
At
this moment the power transistor turns
"OFF"
and the current
Iz
is
abruptly shut resulting
in the high voltage generated in the secondary coil which produces sparks at the spark plug.
The operating timing
of
the advancing controll circuit advances in accordance with the increase
of
engine speed resulting in the advancing
of
ignition timing as shown in
Fig.
66.
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42
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