GKN evolves eAxle

DRIVETRAIN specialist GKN Driveline has taken the lessons it learnt developing final drive axles for plug-in hybrid supercars and applied them to a new lower-cost unit, offering more flexibility for manufacturers developing small electric vehicles.

The British company’s eAxle quite literally cut its teeth on projects such as the Porsche 918 Spyder and then with a two-speed unit under the bonnet of BMW’s i8, but GKN is now offering the technology to manufacturers of more everyday, affordable cars.

Weighing about the same as a bag of cement (20.9kg), the latest evolution of the single-speed eAxle is, according to GKN, now compact, light and cheap enough for applications in the higher-volume markets for plug-in hybrid electric vehicles (PHEVs), bringing the fuel-saving technology within reach of more motorists.

In addition to driving just one set of wheels, the company says its hybrid solution is the only one of its kind that can accommodate four-wheel-drive systems, broadening its applications and appeal to car manufacturers.

GKN has not revealed which brands will be next to adopt the new model, but has confirmed that Volvo selected the eAxle for its new XC90 T8, and has previously worked with PSA Peugeot Citroen as well as BMW and Porsche.

With a reduction ratio of 12.5, the single-speed, two-stage transmission can provide up to 2000Nm of torque and a more modest 65kW of power when under pure electric drive, slashing 0-100km/h acceleration of internal combustion-powered small cars by “several seconds” while cutting fuel consumption by “more than 50 per cent”, the company claims.

How much combustion power is added to the electric drive is down to the individual manufacturer and the engine options available to them.

When cruising at higher vehicle speeds, the eAxle disconnects the electric drive from the transmission to limit the effects of aerodynamic drag on battery life.

GKN Driveline eDrive Systems managing director Rainer Link said the evolution of the eAxle would attract more manufacturers to its range of specialised transmissions.

“GKN’s position as the only hybrid technology supplier that can also deliver complete all-wheel-drive systems makes us an ideal partner on these programs,” he said.

“Our vehicle integration teams can support auto-makers in the tuning of their vehicle’s eAWD mode, ensuring that the torque delivery results in the right front/rear balance and delivers the brand’s trademark driving characteristics.”

Various car-makers are starting to introduce models in the smaller and more affordable end of the PHEV and pure electric markets, such as Audi and its A3 e-tron and the BMW i3, but with suppliers such as GKN shaving the cost of componentry, more brands are likely to eye the segment.

From a four-wheel-drive perspective, all-paw purveyor Subaru has recently announced that its new global platform would accommodate electric and hybrid drive, and the Japanese car-maker could be one of many brands considering the GKN solution.

An evolution of the more compact eAxle could also result in multi-speed versions for affordable PHEVs, borrowing technology from the BMW i8 sportscar for a boost to performance of C-segment hybrids.

Lexus recently followed BMW’s lead into multi-ratio electric drive transmissions with a four-speed automatic transmission for the Multi Stage Hybrid system that drives its LC500h sports coupe.

Like a combustion engine gearbox, adding ratios to an electric motor allows torque multiplication for improved performance and greater motor versatility and efficiency, and more car-makers are expected to introduce the technology as EVs become more commonplace.