Inner-wheel motors and skateboard architecture will allow for bigger cabin space and more complex torque vectoring systems

Advanced drivetrain technology is being developed by automotive engineering firm GKN to enable future electric cars to mix extreme performance with agility and excellent traction.

The British company, which has contributed to the drive systems of models such as the BMW i8, Porsche 918 Spyder and Ford Focus RS, expects its future technology to include inner-wheel electric motors, allowing for continuous control of torque to each wheel.

“Right now, the technology is not there for us to produce these compact electric drivetrains in sports cars, where big power is needed,” said Theo Gassman, GKN’s director of advanced engineering and eDrive systems. “But for city cars, where the power output of each motor has to be only 20kW or 30kW [27-40bhp], maybe it’s not so far away.”

Gassman said this individual motor layout allows for full torque vectoring, improving agility and traction control. It could also enable the use of smaller brakes because each motor can turn into a high-drag generator that can slow the car as it regenerates energy.

“In city cars, when we move the motors into the wheels, it also means we can use a skateboard architecture layout, with no transmission tunnel or space needed for a combustion engine,” said Gassman. “It provides lots of opportunity for cabin space.”

Because of the larger motors needed to power them, performance-biased electric models are likely to continue to use centrally mounted motor modules - such as GKN’s eAxle - for many more years. “With this set-up, you can have two eAxle modules in one car, one powering each end,” said Gassman. “The BMW i8 has one in its front, but with two the torque levels are much bigger.”

Tesla employs this kind of layout with its most potent all-wheel-drive Model Ss. But Gassman believes GKN’s drive modules are the best in the world. He suggested that if two were integrated into a new sports car, the performance potential would be unrivalled.

“We’re working towards becoming a complete driveline supplier, so we supply everything from the power electric [motor] to the CV joints that connect to the wheels,” said Gassman. “Our first complete driveline will be featured in a new model in the coming years, maybe 2018 or 2019.”

Gassman refrained from revealing which new model that would be, but he confirmed it will be a hybrid. “Hybrid power is still the best solution for today’s vehicles,” he said, before confirming the electrified part will produce up to 1475lb ft of torque and be highly modular.

“We can scale this driveline up or scale it down, so it can be used in multiple platforms,” said Gassman. This suggests it’s on course to feature in other cars.

GKN’s integrated electric drive system could transform the EV market

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6 October 2016
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