Electronic ignition is nothing new. Many “electronic”
ignition systems still rely on mechanical properties of
the distributor for RPM sensitive modifications
(advance/retard) and for actual spark “distribution”.
The proposed system uses a PIC12C508 for total
spark control on a 4-cylinder engine. This system could
be adapted to 6 and 8-cylinder engines by using a
“double-fire” (firing on power and exhaust strokes).
In this system, each cylinder has its own high voltage
coil, allowing a “hotter” spark than is supplied through
the arcing and inaccuracies of a mechanical distributor.
The PICmicro could use either a single or dual sensor
(IR) reading from a “code-wheel”. The dual system
would indicate top dead center of cylinder #1 (or some
other relevant timing mark) and single marks for each
cylinder. The single sensor system would only require
the TDC detector.
The PICmicro would time TDC detections, thereby
determining engine RPM. This RPM would be used in
a lookup table to determine the spark timing (single
sensor) or cylinder detect (dual). Each cylinder would
fire at the appropriate time.
System Benefits:
(over a mechanical design)
Inexpensive processing power means system can be
easily tuned for performance/emissions or other criteria.
Stronger, more accurate spark can be delivered.
No parts to wear, arc, or corrode.
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