Environmental Engineering Reference
In-Depth Information
The interpretation of the Japan 10-15 mode is that mode 10 is repeated three
times followed by a single occurrence of mode 15. Independent testing laboratory
validation of economy and emissions can test to mode 10 only or mode 15 only or
the combined 10-15 mode as shown in Figure 9.14.
In Chapter 1 the conversion between fuel economy in mpg to or from fuel
consumption in L/100 km was presented. European and Japanese economy certi-
fications are done in metric units of L/100 km that must be converted to fuel
economy for comparison of hybrid technologies.
9.6 Regulated cycle for hybrids
This chapter was introduced with the assertion that present drive cycles may not be
adequate to properly characterize hybrid vehicles given the changing traffic flow
patterns and demographics in the more than two decades since many of these drive
cycles were introduced. Most regulated drive cycles came into existence during the
early to mid-1970s when interest in BEV was high. The oil shock and embargos of
the 1970s fuelled this interest in EVs, and today the interest continues for much the
same reasons, but with hybrid and fuel cell technology in place of battery-only
electric drives.
The introduction of combined drive cycle economy predictions based on
transportation surveys resulting in UF and MWP functions is a good indication that
a need exists. How this will be done rests on how regulating authorities seek to
model the driving habits of major metropolitan centres and geographical areas and
then merge the resulting statistics into some more meaningful drive cycle. Whether
or not a generic drive cycle for passenger vehicles can ever be developed that has
the consistency of bus route drive patterns is unlikely, and perhaps it will require
one or more cycles for each of the populated continents. Testing and validation data
show that hybrids perform differently on the various cycles, all else being equal.
In Table 9.4 it can be seen that IPMM/Gs are the most often introduced tech-
nology as is the NiMH battery.
Table 9.5 summarizes the present trend to raise the performance levels of
hybrid vehicles. In a conventional passenger vehicle the globally accepted perfor-
mance metric is a peak propulsion power of 10 kW/125 kg of vehicle mass. As can
be seen in Table 9.5, early hybrid vehicle introductions were all sub-par in this
sense. Only with the just announced introduction of the new Prius by Toyota has
the performance metric been met. The new Prius (THS-II) is slated to deliver ~55
mpg on the US-combined cycle versus 44.8 mpg for the earlier Prius (THS-I). This
is due in large part to an impressive maximum engine efficiency of 37%. The
production Corolla vehicle for comparison achieves 39.2 mpg (61/100 km) from its
1.5 L, IY, four speed AT.
The Toyota Hybrid Synergy Drive (THS-II) will deliver 2.8 L/100 km on the
Japan 10-15 mode (84 mpg); 4.3 L/100 km on the US M-H cycle (54.7 mpg) and
4.3 L/100 km on the ECE cycle (54.7 mpg).
