Environmental Engineering Reference
In-Depth Information
2.8.2 Production 'Estima Van' example
Adding on demand electric propulsion to the non-driven axle benefits the overall
vehicle performance, depending on whether this axle is the front or rear. In a front
wheel drive vehicle the ICE driveline remains at production level but an electric
M/G is then added to the rear axle. Rear axle propulsion power levels are significantly
lower than front axle levels due to a need to maintain longitudinal stability. A power of
15-20 kW peak provides adequate axle torque for grade, split mu and stability enhance-
ment in a passenger sedan to medium SUV class of vehicle. Recall that regeneration
levels at the given power levels recuperate most of the available energy (Figure 2.45).
Figure 2.45 Electric four wheel drive (Toyota Estima Van)
2.9 Exercises
Q1: A narrow lane vehicle of the type shown in Figure 2.2 is driven at steady speed
of 55 mph on level grade with no headwind. (a) What is the total propulsion
power required? (b) What is the energy consumption rate (Wh/mi)? Given
that C rr = 0.007 kg/kg, A f = 1.12 m 2 .
Hint: Set P ( V )= P inertial + P roll + P aero + P grade
(1) P inertial ¼ð
V V
M v þ
M pass Þ
(2) P roll ¼ gM tot C rr V
(3) P aero ¼
2 r air C d A f V 3
(4) P grade ¼ gM tot sin q
1
A1:
(a) 2,195.15 W; (b) 40 Wh/mi
Q2: Repeat Q1 for the case of 15 mph headwind. What will be the total range in
this case before fuelling up is necessary?
For the case of V w = 15 mph, P ( V ) = 2195.15(31.3/24.6) 3 = 4521.6 W a
factor of 2.06 higher, therefore, the range is reduced to 1/(2.06) = 0.485. So,
less than half the range without headwind.
A2:
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