Environmental Engineering Reference
In-Depth Information
14 V
42 V
1,200
Integrated into
rack-concentric
800
Rack mounted
pinion drive
Column
mounted
400
7
8
9
10
11
12
Rack load (kN)
Figure 9.7 EPS system: ( left) voltage versus rack loading; (right) rack mounted
EPS unit
hybrid vehicle battery and used during launch and boosting to augment the fuel cell
output. Generally, a load of 700 W is used in hybrid vehicle characterization.
The preceding discussion is an attempt to show that fuel economy and emis-
sions in hybrid vehicles have a strong correlation with drive cycle characterization.
In the following sections some of the more important drive cycles are presented,
along with discussion on why these are used.
9.1 City cycle
The US EPA city cycle is the first 1,300 s of the Federal Test Procedure, FTP75,
regulated cycle charted out in Figure 9.8. From Table 9.3 the city cycle has an
average speed of 34 kph (21.3 mph) and a peak speed of 94.3 kph (58.9 mph) [8].
Emissions testing laboratories characterize the vehicle according to the city
cycle, or urban portion of the FTP. Figure 9.9 is the urban drive cycle used by
independent testing laboratories to validate economy and emissions of passenger
vehicles. The city cycle is an aggregate of representative urban stop-go driving.
Because of the high percentage of stop time (Table 9.3) and acceleration/
7.00E+01
6.00E+01
5.00E+01
4.00E+01
3.00E+01
2.00E+01
1.00E+01
0.00E+00
-1.00E+01
Time (s)
Figure 9.8 Federal Test Procedure, FTP75
