Capacitive Discharge (Fixed Timing) Ignition System; Capacitive Discharge Ignition Module Schematic - Kohler CH18-745 Service Manual

Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Kill Switch or
''Off'' Position of
Key Switch
Figure 8-4. Capacitive Discharge (Fixed Timing) Ignition System.
The timing of the spark is controlled by the location of the flywheel magnet group as referenced to engine top dead
center.
L1
Figure 8-5. Capacitive Discharge Ignition Module Schematic.
Operation: As the flywheel rotates, the magnet
grouping passes the input coil (L1). The corresponding
magnetic field induces energy into the input coil (L1).
The resultant pulse is rectified by D1 and charges
capacitor C1. As the magnet assembly completes its
pass, it activates the triggering device (L2), which
causes the semiconductor switch (SCS) to turn on.
With the device switch "ON," the charging capacitor
(C1) is directly connected across the primary (P) of the
output transformer (T1). As the capacitor discharges,
the current initiates a fast rising flux field in the
transformer core. A high voltage pulse is generated
from this action into the secondary winding of the
transformer. This pulse is delivered to the spark plug
gap. Ionization of the gap occurs, resulting in an arc at
the plug electrodes. This spark ignites the fuel-air
mixture in the combustion chamber.
Electrical System and Components
(0.28/0.33 mm)
0.011/0.013 in. Air Gap
D1
C1
SCS
L2
B. Capacitive Discharge with Electronic Spark
SMART-SPARK
electronic capacitive discharge ignition system with
electronic spark advance. A typical application (Figure
8-6) consists of the following components:
• A magnet assembly which is permanently affixed
• Two electronic capacitive discharge ignition
• A spark advance module which mounts to the
• A 12 volt battery which supplies current to the
• A kill switch (or key switch) which grounds the
• Two spark plugs.
www.mymowerparts.com
Ignition
Modules
Magnet
Flywheel
T1
P
S
Advance (SMART-SPARK
equipped engines utilize an
™
to the flywheel.
modules which mount on the engine crankcase
(Figure 8-6).
engine shrouding (Figure 8-7).
spark advance module.
spark advance module to stop the engine.
Section 8
Spark Plug
Spark Plug
).
™
8.5
8