UK – The latest axle drive product, eAxle, will enable the addition of plug-in electric all-wheel drive (AWD) on a range of new C-Segment vehicles, the first application being the BMW 2 Series Active Tourer PHEV. Production is now underway at the company’s eDrive plant in Bruneck, Italy.“GKN’s eAxle technology is passing a key milestone in its evolution at a time when the demand for all-wheel drive and plug-in hybrids is strengthening,” commented Peter Moelgg, automotive president of engineering. “This latest system advances the business case for electric, all-wheel drive capability in hybrids. A number of automakers are introducing our technology on their premium models and starting to transfer eAxle hybrid versions of higher-volume models.”
GKN’s eAxle evolved out of systems developed for hybrid supercars which use eAWD to enhance performance and efficiency; the latest version has been optimised for compact-car applications. The unit weighs 20.2kg and measures 457mm by 229mm by 259mm, facilitating packaging and installation in confined spaces.
The single-speed design has a transmission ratio of 12:5:1, reducing the electric motor speed in two stages. The system generates as much as 2,000Nm and 70kW of additional torque and power, enabling speeds of up to 125km/h in pure electric mode and faster acceleration than conventional, mechanical AWD. When hybrid operation is not required, the e-machine can be disconnected from the driveline by an integrated device which uses an elecro-mechanically actuated dog clutch. GKN says this minimises rotating losses at higher speeds when disengaged.
Further benefits include gear and bearing arrangements optimised for efficiency and durability, plus noise, vibration and harshness; and precision engineering throughout to ensure a low-backlash, high-performance transmission differential and case providing seamless shifts between pure electric, hybrid and conventional modes.
According to GKN, the latest generation of eAxles offer a step forward in terms of performance, size and cost, arguing that for many front-wheel drive platforms it is now “simpler and more effective” to electrify the rear axle than to bolt on a hybrid module to the main transmission. Input speeds of 14,000rpm are currently possible, and expected to exceed 20,000rpm in the near future.
GKN launched its first eAxle products in 2002 and contributed to the plug-in hybrid Porsche 918 Spyder programme; the first two-speed eAxle was introduced in the plug-in hybrid BMWi8. The technology is also used on the Volvo XC90 T8 Twin Engine PHEV.