Environmental Engineering Reference
In-Depth Information
Wolfsburg to Hamburg to VW's 42nd stockholders' meeting at speeds of 100 kph
or higher and averaging less than 1 L/100 km fuel consumption. The vehicle has
a range of 650 km on its 6.5 L of fuel, has a drag coefficient of 0.159, less than a
fighter jet, and a width of only 1.25 m.
The VW Tandem uses a specially designed, lightweight, automatically shifted
step ratio manual transmission. The gearbox is a 6-speed electronically shifted unit
designed to match the powertrain to European driving. The driveline is designed to
disconnect the engine from the wheels during coasting, effectively converting the
vehicle into a glider, to conserve fuel. Launch and regenerative braking are accom-
plished using the integrated starter-alternator (ISA) and a small nickel-metal hydride
(NiMH) battery. An electronic stability programme (ESP) provides longitudinal and
lateral (yaw motion) stability on different road conditions and driving scenarios.
The DCX F400 and VW Tandem are early examples of the type of vehicle
architecture proposed by the author and others as dual mode vehicles capable of
both highway driving and as an autonomous vehicle on special guideways. Patent
literature is now showing signs of increased activity in this area of hybrid propul-
sion, in what could be called 'tribrid', for three independent propulsion technolo-
gies per vehicle rather than two. A vehicle like the VW Tandem with its narrow
body structure, four wheels and CIDI-electric propulsion could also be augmented
with a means for non-contacting power transfer to the vehicle on specially equipped
guideways. The guideway itself remains inert, except for a propulsion reaction
plate embedded in its surface energized only by a passing vehicle and containing
route guidance, vehicle propulsion control and vehicle spacing for very high den-
sity traffic [4-8]. Proposals for guideway travel are focused on dual use vehicles
under autonomous control travelling on special guideways at speeds ranging from
150 to 500 kph for personal transport. There are systems under development in
which speeds of 150 kph are working.
At the 2009 Frankfurt auto show, Volkswagen displayed the new Tandem called
the L1, an updated version of the 2002 Tandem. The L1 is equipped with an 800 cc,
2-cylinder CIDI derived fromVW's 1.6 L Turbo Direct Injection (TDI) and provides
the Tandem a fuel economy of 189 mpg. With a 10 L fuel tank, the 380 kg L1 can
achieve a range of 670 km while emitting only 39 g CO
2
/km. A drag coefficient
C
d
=
0.195 certainly contributes to this range figure. Acceleration boost in the L1 is
achieved with a 10 kW electric motor by 40%, much like the Honda IMA system.
These specialty vehicles are mentioned because hybrid propulsion should not
be thought of as some ad hoc modification of a production platform to squeeze out
a few more mpg, or even as a ground up design for purpose built hybrids, but in the
larger context as fundamental constituents of a transportation system. Automotive
companies must ask themselves whether they are in the business of building pas-
senger vehicles, or if they are in the transportation business. In this larger context of
transportation systems, it is not only propulsion technologies but the highway
infrastructure that must be considered.
Chapter 2 continues with an expos´ of the various powertrain architectures
available to the vehicle designer, their benefits and disadvantages, and why a par-
ticular architecture is selected for a specific vehicle in a particular market.
