| Efficient Dynamics' is the declared
goal of the BMW Group's drivetrain development division. " This resolves
the apparent conflict between reducing consumption and emissions on the
one hand and enhancing performance and agility on the other," commented
Professor Burkhard Göschel at the Vienna Motor Symposium. It means
that the requirements for environmental compatibility and consumption
are not viewed in isolation but in the context of the close interplay
between statutory requirements, social acceptance and customer demands.
"An important component in developing drive technology lies
in intelligent electric power for the drive, for example through an 'active
gear', combined with high-performance capacitors. Developing a hybrid
vehicle that drives for long distances on electric power is not commercially
viable over the long term and is therefore not goal-oriented.
Not everything that is technically feasible is also economical and ecological.
And, most importantly, it doesn't necessarily convince the customer. An
intelligent drive where power can be called up at any time and which provides
more spontaneity for less consumption is a realistic development proposition,"
emphasises Professor Göschel.
Option for the future: 'Efficient Dynamics' with electrified drivetrain
BMW has already played through an extreme initiative. An electric motor
integrated into a BMW X5 experimental vehicle between the internal combustion
engine and the gearbox supports the conventional drive during acceleration.
The research vehicle was launched in 2003 and produced responses that
had never been attained before, while also increasing torque to 1000 Nm
in the lower range. On the other hand, the vehicle also reduced consumption
by up to 15 per cent in the driving cycle.
Looking into the future, Professor Göschel can imagine a compact
'active gear' that integrates the electric motor and the power electronics
in a single assembly within the gearbox. This will significantly reduce
the additional weight and the construction space required for the system.
High-power capacitors, elegantly stowed in the door sill, could contribute
to an additional benefit. By comparison with battery systems, capacitors
have significantly higher charge and discharge rates over the short term.
As Professor Göschel sees it, the function of an intelligently honed
drive is to intervene electrically in the drivetrain and optimise driving
situations like stop-and-go traffic or acceleration.
Long-term development potential is with the internal combustion engine
However, all concepts geared towards intelligent electrification remain
no more than an auxiliary solution for the internal combustion engine.
BMW has significantly reduced consumption and emissions in diesel engines
during recent years, while simultaneously increasing performance and torque.
Valvetronic, the fully variable valve control system, has allowed BMW
to achieve comparable improvements in the petrol engine. In future, the
introduction of spray-guided direct injection and the implementation of
lean combustion will bring consumption in the petrol engine closer to
values attained by modern diesel units.
Over the long term, hydrogen is still reckoned to be the fuel with the
greatest potential for safeguarding mobility in the future. BMW specialists
are working on the hydrogen combustion engine, where an overall efficiency
of up to 50 per cent is conceivable in the long run.
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