Chapter 22 Hybrid Drive Systems 429
In the engine starting mode, the power control module
routes battery pack energy to both the front and rear motor-
generators. The rear motor-generator continues to propel
the vehicle while the smaller front motor-generator spins
the engine crankshaft until the engine starts and runs on its
own power. See Figure 22-16B.
During highway cruising, the engine spins the drive train
directly. It also spins the front motor-generator. This allows the
front motor-generator to power the rear motor-generator and
also recharge the battery pack. Look at Figure 22-16C.
Under full acceleration, the engine applies full crankshaft
torque to the drive line. It also spins the front motor-generator
to produce electrical energy. This electrical energy and energy
from the battery pack are both fed to the rear motor-generator.
This allows the engine, both motor-generators, and the battery
pack to propel the vehicle. Refer to Figure 22-16D.
During deceleration and regenerative braking, the drive
line spins the output shaft of the transmission. This torque is fed
to the rear motor-generator. The rear motor-generator serves as
a generator to recharge the battery pack and place a drag on
the drive line to slow the vehicle. See Figure 22-16E.
When the transmission is shifted into reverse, the vehi-
cle again acts as an all-electric vehicle using battery pack
power and the rear motor-generator to propel the vehicle.
This is illustrated in Figure 22-16F.
A cutaway view of a transaxle with two motor-
generators is shown in Figure 22-17. A cutaway view of
a rear-wheel drive transmission with two hybrid motor-
generators is given in Figure 22-18.
Triple Motor-Generator Hybrid
A triple motor-generator hybrid uses three motor-
generators in one vehicle drive train, Figure 22-19. Two
motor-generators are located in the transmission or transaxle,
and one can be located in the rear drive axle assembly. A triple
motor-generator arrangement is often used in four-wheel drive
vehicles to help electrically drive all four wheels and tires.
Figure 22-20 shows a front hybrid transaxle and a rear
hybrid transaxle for a triple motor-generator hybrid drive
line. The rear transaxle allows the third motor-generator to
rotate the rear drive axles.
Hybrid Power Cables
Hybrid power cables transfer huge amounts of cur-
rent to the high-voltage components of the electric drive
system. The power cables are heavily insulated to prevent
these voltages from shorting to ground.
Two large HV battery pack power cables connect to the
power control module. Three large power cables connect the
power control module to the motor-generator. These three
cables are normally routed under the fl oor pan on the inside
of the rocker panel. The three high-voltage power cables have
orange insulation to warn technicians of their danger.
Figure 22-17. Study the major parts of this hybrid transaxle for an advanced parallel-series hybrid, front-wheel drive vehicle. (Toyota)
Rear
Motor-Generator
Windings
Rear
Motor-Generator
Windings
Pinion
Gear
Drive Axle
Ring Gear
Front
Motor-Generator
Windings
Transaxle
Input
Shaft
Engine
Crankshaft
Front
Motor-Generator
Windings
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