Interview ”Efficiency is the main Goal at every Level of Automation”
The growing automation of vehicles, right up to ‘autonomous’ automobiles, enables more safety and lower consumption and emissions. What role do transmissions play, and how will they change? We asked Dr. Carsten Bünder, Director Global Product Management at GETRAG, Magna Powertrain.
Issue: #December 2017
Mr Bünder, how will automated driving change traffic?
Automated vehicles drive sensibly by nature. They have a plan, and they communicate and cooperate via Car2X. It’s almost inevitable that vehicles with higher levels of automation will adopt a guiding role among the automobile population – almost like holding a swarm together. That effect will kick in at relatively low numbers of automated vehicles, we could see it fairly soon on highways. The harmonica effects we know today will be smoothed out, we don’t even need Level 5 automation for that. So in that sense both safety, and consumption and emissions, benefit clearly from automated driving.
What role does powertrain electrification play in this?
Automated driving and electrification are not necessarily interdependent. They are parallel developments, but they make almost perfect partners. You can use the opportunities of hybrid drives even more effectively, for instance – for example by tailoring your charging management to your route. When your car knows it’s heading for a city, it will enter the low-emission zone with a fully charged battery. And when you drive home in the evening, the charging system will run the battery flat knowing that your car will be plugged in all night. All that works much more comfortably and predictably with automated driving. Plus, it opens up new ways for the electric motor to support the ICE, for example during stop-and-go, crawling etcetera. That enables simplified hybrid drives like DHTs. Autonomous driving and Car2X interact here, theoretically from just Level 3 partial automation on.
Automated driving means people will expect more comfort too. What does that mean for transmissions?
That’s true, the driver basically becomes a passenger and is much more aware of the car. NVH requirements will rise sharply because as a passenger, you notice all the influences from the drive train. Again, a hybrid’s e-motor can help here by partially absorbing or softening NVH influences from the engine or transmission. NVH performance on all-electric drives is very good per se, but for larger speed spreads they too need load-shift enabled transmissions that can span large ratio steps comfortably. Looking ahead though, I see all-electric drives mainly in inner cities.
Wouldn’t stepless transmissions be better there?
As I said, Car2X communication, further automation and the support from the e-motor improve comfort significantly for step transmissions too. But we shouldn’t lose sight of the real purpose of automated driving. No matter what automation level people use –conventional, partial or full – the focus is always on lower consumption and minimal emissions. And in terms of physics, multiple-step transmissions like a DCT do have a clear advantage. Then if we can add support from the e-motor, we’re pretty close to the optimal combination of efficiency and comfort.