Gearbox of Porsche Taycan - 'lonely' in the tram village

Taycan has a two-speed gearbox, while most electric vehicles currently use only a single-speed gearbox.

What is attractive about Porsche Taycan? 750 horsepower, acceleration 0-100 km / h under 3 seconds, the ability to fully charge the battery in just 20 minutes? These were partly due to the German automaker integrating a two-speed gearbox-type sports sedan - a strange thing on electric cars, which use a one-speed gearbox.

The one-speed gearbox on most electric vehicles still works quite well. Internal combustion engines need a multi-speed gearbox because each gearbox only provides a limited rpm range. As for the electric motor, the range of the rpm is much larger, so the gearbox will satisfy both fast acceleration at low speed as well as driving on the highway. Autobahn (Germany) seems appropriate, where cars often reach over 200km / h (Tesla limits their cars to 262 km / h), while the Taycan can reach 260.

Taycan gearboxes are a solution developed by Porsche himself. We will not be able to get the gearbox of a racing car in Formula E to mount a car for daily commuting. But a well-known transmission supplier like ZF is also working with their prototype electric two-speed gearbox. The object they target is that manufacturers do not want to sacrifice one of the characteristics is great traction at low revs and incredible acceleration.

Porsche Taycan was launched in Singapore, November 2019. Photo: Quang Anh

"With a two-speed gearbox, we can keep both," says ZF's E-Mobility technical lead, Stephan Demmerer. For carmakers, setting up two shifts can improve their driving distances by 5% or push their maximum speed far beyond expectations.

The system does just that by increasing the conversion rate from the battery's power source to the actual power at the wheel. Each improved percentage point will result in an additional 2% of the increased travel distance, according to ZF. Their two-speed gearbox is a module, which can be mounted on many vehicles, it will connect an electric motor to create a maximum power of 140 kW (188 horsepower).

The gearbox is programmed to switch between the two speeds at 69 km / h, although the computer can intervene to shift gears at other speeds based on the distance, terrain or the estimated driving distance. Need to recharge the battery. Companies can use this system to optimize their travel distance by combining a small set of batteries (which helps cars reduce weight) or optimizing power by pairing them with larger batteries.

"There is indeed a race to create more energy efficient electric cars," said Venkat Viswanathan, a mechanical engineer at Carnegie Mellon University. "Tesla is maintaining the leading position in this race with a single-speed gearbox, and I think the rise of ZF will create opportunities for other manufacturers to take advantage."

The new two-speed gearbox hasn't exploded yet because it's so complicated. Multi-speed gearboxes must be powerful enough to provide a large rpm range, while electric motors can do the same in a very short amount of time, according to Shashank Sripad, another mechanical engineer of Carnegie Mellon. Tesla has tried to prove this with the Roadster concept more than a decade ago, but has faced reliability challenges and they've been stuck with only one-level gearbox technology ever since. And because more maintenance is required, new gearbox technology can affect the appeal of electric vehicles.

Moreover, developing more than one level up to date is not really necessary. "The small panels will provide enough distance for about 100 to 150 km, and users are mostly urban," Demmerer said. "But we are also seeing increased demand at highways, and the required travel distance has also increased."

Two-level configuration will be applied when customers use for many different purposes, and obviously 5% of the improved distance will save you more money while the storage capacity of the battery is getting better. . In fact, the two-speed gearbox will provide the most economical operation for vehicles with larger battery packs or power-driven vehicles. As for customers moving for urban purposes, it seems their trend of choosing a single-speed gearbox has not changed.

Unless you can afford to buy a sleek new Taycan, don't wait to be able to use this technology. ZF has not announced which carrier will use the new gearbox, and is unlikely to be ready for market in the next three years.