Electric all wheel drive for smaller vehicles

The GKN eAxle

GKN Driveline is making electric all-wheel drive a possibility for smaller hybrid and electric vehicles with its eAxle technology.

A series of new vehicles will offer consumers the option of adding plug-in electric all-wheel drive using GKN Driveline’s latest electric axle drive (eAxle) technology. The eAxle is an evolution of systems developed for hybrid supercars that use electric all-wheel drive to boost performance and efficiency.

GKN has secured orders for a major global platform and production is now underway at the company’s eDrive production facility in Bruneck, Italy. The first application is the BMW 2 Series Active Tourer PHEV.

GKN Driveline Chief Executive Phil Swash said: “GKN Driveline continues to bring the future of eMobility into the here and now. Our total focus on driveline innovation, our unmatched expertise in all-wheel drive and our 14 years of production experience in eAxles are now making eAWD viable in smaller, more affordable vehicles. From the i8 to the 2 Series Active Tourer, GKN’s work with BMW reflects our position as the development partner of choice for the coming wave of plug-in hybrids with eAWD.”

Hybrid power for compact cars

The company’s new electric axle drive has been optimised for compact car applications. The lightweight single-speed design has a transmission ratio of 12.5:1, reducing the electric motor speed in two stages. The system generates up to 2,000Nm and 70kW of additional torque and power – enough for a vehicle’s pure electric mode to achieve speeds of up to 125km/h and for an all-wheel drive (AWD) mode that accelerates considerably faster than conventional mechanical AWD systems.

The entire unit weighs just 20.2kg and has a length of 457 mm, a width of 229 mm and a height of 259 mm, facilitating packaging and installation in confined spaces.

When hybrid operation is not required, the e-machine can be disconnected from the driveline by an integrated disconnect device, which uses an electromechanically actuated dog clutch. This minimises rotating losses at higher vehicle speeds when disengaged. Gear and bearing arrangements have also been optimised for efficiency, NVH and durability. Precision engineering throughout the system, including a low backlash, high performance transmission differential and case ensures transitions between pure electric, hybrid and ICE modes are transparent to the driver.

Efficient eAWD capability

The latest generation of GKN eAxles represent a significant breakthrough in terms of performance, size and cost. For many front wheel drive vehicle platforms, it is now simpler and more effective to electrify the rear axle than to bolt on a hybrid module to the main transmission.

GKN Automotive President of Engineering Peter Moelgg, said: “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. This latest system advances the business case for electric all-wheel drive capability in hybrids. A number of automotive manufacturers are introducing our technology on their premium models and starting to transfer eAxle hybrid versions of higher volume models.”

eAxles transmit the electric torque directly to the vehicle’s wheels, providing more immediate response and dynamic acceleration. Input speeds of 14,000rpm are now possible and are expected to exceed 20,000rpm in the next few years – far higher than is possible with hybrid transmissions.

GKN launched its first eAxle applications in 2002. The company was awarded Official Porsche Technology Partner status for its contribution to the plug-in hybrid Porsche 918 Spyder programme. It launched the world’s first two-speed eAxle in the plug-in hybrid BMW i8 and also supplies the eAxle on the Volvo XC90 T8 Twin Engine PHEV programme.

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