ker88839_ch08.qxd
1/9/06
11:28 AM
Page 171
Charging System Operation
171
B IG
STATOR COIL B
IG
IGN.S/W
S
S
L
L
Tr2 F
Tr1
CHARGE LAMP
Tr3 ROTOR COIL
P E E
IC REGULATOR
MONOLITHIC INTEGRATED CIRCUIT
Figure 8-56. When AC generator voltage is too high, the regulator momentarily cuts off current to the rotor coils, eliminating the magnetic field. The rotor continues to spin, but no voltage is generated. (Reprinted by permission of Toyota Motor Corporation)
battery voltage, it redirects current to switch off the charge lamp. During normal operation, AC generator voltage exceeds the typically specified 14.5 volts at times. To protect the battery and delicate components in the electrical system, the IC regulator shuts off current to the rotor, cutting AC generator output to zero (Figure 8-58). Note that even though the AC generator is momentarily “turned off,” the charge lamp does not come on. Within a split second, the IC regulator re-energizes the rotor again once output falls below the minimum. The IC regulator switches battery voltage on and off this way to control output and maintain system voltage at an ideal level.
AC GENERATOR (ALTERNATOR) DESIGN DIFFERENCES Original equipment manufacturers (OEM) use various AC generator designs for specific applications. It has been noted that such factors as maxi-
mum current output and field circuit types affect AC generator construction. The following paragraphs describe some commonly used automotive AC generators.
Delphi (Delco-Remy) General Motors Applications Delphi, formerly the Delco-Remy division of General Motors Corporation, is now a separate corporation that supplies most of the electrical devices used on GM vehicles, as well as those of some other manufacturers. The trademark name for Delco-Remy alternators was Delcotron generators. The alternator model number and current output can be found on a plate attached to, or stamped into, the housing.
DN-Series The 10-DN series AC generator or alternator uses an external electromagnetic voltage regulator. Six individual diodes are mounted in the rear housing (Figure 8-59) with a capacitor for protection. A 14-pole rotor and Y-type stator
