Environmental Engineering Reference
In-Depth Information
Example 3: At 5% FE gain on a 27.5 mpg vehicle that is driven 15,000 mi/year
commuting, what must the StARS type auto-stop system on-cost be to realize a
3 year payback?
Assume: Gasoline at $3.00/US gallon.
Solution: At the stated FE gain and for a total of 45,000 mi commuting over three
years, given the fuel price leads to a savings of C = 251.8 gallons $3.00/gallon =
$755.
Compare this with the on-cost charts in Chapter 1 and note that
this is
approximately the target price a customer would need to see.
2.2.3 Mild hybrid
Figure 2.11 illustrates an ISA, also known as integrated starter-generator (ISG),
system proposed for mild hybridization of a sport utility vehicle.
Fuel
Battery
rt, F r
P acc
T e
T isg
GR
I
S
G
ICE
FD
T e
T prop
U
mv
Figure 2.11 Mild hybrid architecture (42 V PowerNet)
The immediate fact to glean from the mild hybrid architecture shown in
Figure 2.11 is the presence of a single clutch and the direct connection of the M/G
(labelled ISG) to the engine crankshaft. This is the classic pre-transmission parallel
hybrid architecture. The driveline torque summation point occurs at the drive clutch
friction plate side with reaction plate connected directly to the transmission input
shaft. In the case of an automatic transmission, the M/G would be integrated
directly into the torque converter impeller donut (either axially or radially at the
interior or exterior, respectively).
The second point to notice from Figure 2.11, and not explicitly shown, is the
voltage level of the M/G power source. The battery in this mild hybrid archi-
tecture complies with the 42 V PowerNet standard. Nominal voltage is 42 V and
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