SECTION
3
Ignition Operation
The firing of the spark plug at the proper time is the
culmination of a number of components working
together. In the TC3000,
TC4000,
and TC5000 the
components used are:
Flywheel
Ignition Coil
Trigger Module
Spark plug
See Figure
51.
SPARK PLUG,
a
TRIGGER
MODULE
Figure
51
The following describes the function of each of the above
components.
Ignition Operation Flywheel
The flywheel is connected directly to the crankshaft and
turns at the same speed as the engine. Imbedded in the
flywheel are three magnets. These magnets rotate past
the coil to generate electricity.
Imbedded in the opposite side of the flywheel is a steel
counterweight which offsets the weight of the three
magnets.
It
is not magnetic.
Ignition Operation Ignition Coil
The ignition coil is actually a transformer.
It
is positioned
close to the flywheel to allow the magnetic field of the
IGNITION
flywheel magnets to cut through the coils to generate
electricity. See Figure
52
IGNITION
COIL
Low voltage is produced in the primary coil which
is
sent
to
the trigger module. The primary voltage is much too
low to produce a spark at the spark plug.
The secondary coil serves
to
amplify the voltage
produced in the primary. To accomplish this, the
secondary coil must have many more windings than the
primary. The higher the ratio between the primary coil
windings to secondary coil windings, the greater the
voltage amplification will be.
However, even though the secondary coil in the TClOOO
has considerably many more windings than the primary,
the voltage produced is still not high enough to produce
spark across the spark plug electrodes. To further
amplify the voltage, the trigger module is used
Ignition Operation Trigger Module
The trigger module amplifies the voltage in the
secondary coil by breaking the primary circuit just as the
primary voltage reaches its peak. This breaking of the
primary circuit results
in
a rapid collapse of the magnetic
field surrounding the primary coil. The collapse of the
primary magnetic field induces a large voltage surge in
the secondary which is sufficient to produce a spark
across the spark plug electrodes.
Before getting into the actual electronics used inside the
trigger module,
it
is important to have an understanding
of the voltage waveform produced by the flywheel
magnets moving by the ignition coil.
See
Figure
53.
25
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