ZF EcoLife - The latest Generation of Powershift Automatics for Transit Buses 2011-01-1423
The megatrends "reduction of emissions" and "fuel
consumption reduction" play a predominant role in the
development of powertrains.
For transit buses this implies both the reduction of emissions
and pollutions of the internal combustion engine, and, on the other
hand, a further reduction of noise and brake dust. Also very
important is the reduction of both fuel consumption and CO₂
emissions.
For all these targets the actual developments on the engine side
have led to great improvements in the last decades, but what can be
mentioned for the other components of the powertrain, especially
looking for transmissions?
First of all the relevant trends for transit buses have to be
considered:
A large increase of the torque of the combustion engines during
the last years has a big impact on the development of transmissions
for buses.
Furthermore, due to the higher coolant temperatures of the
engine's cooling systems to perceive a better emission behavior
because of a better efficiency of the combustion engine, coolant
systems for the transmissions have to be improved as well.
For transit buses in established markets powershift automatics
have a share of more than 90%.
The presentation will give the most recent developments for both
hardware- and function-related parts of the transmissions. The
function and software parts demonstrate the increasing influence of
electronics and their interactions within the vehicle's
electronic architecture. All the different vehicle electronics are
driven collaborative to achieve best suited solutions for the
different areas of customer's requests.
The development of modern powershift transmissions today means
also an intensive use of simulation tools for all fields. This
exceeds by far the former strength, fatigue and vibration analyses.
Practical examples, also including manufacturing simulation, will
show the relevance of simulation to the development process. All
the simulation results lead to a reduction of development time and
a better product quality and accuracy.
The presentation ends with an evaluation of different hybrid
solutions. Here for the future systems are needed which combine
both fuel consumption reduction and improved life cycle costs.
ZF with its parallel hybrid system will offer a very attractive
solution for the market.
