The eAxle module supports full-electric mode, all-wheel drive and provides a boost function.
The vehicle set a record lap time at Nurburgring and of achieved fuel efficiency of three litres /100km.
The eAxle that supplements the 918 Spyder's hybridised 4.6litre V8 is an evolution of the company's eAxle drive. The module has maximum power of 95kW and can deliver up to 1500Nm of torque to the front wheels via a fixed gear ratio. A specially developed compact differential engages the torque seamlessly, giving optimum power distribution at all times. The differential also disengages the module to minimise drag losses and maximise efficiency. At speeds above 265km/h, a clutch isolates the electric motor to prevent it from over-spinning. To achieve the low centre of gravity and ground clearance, the output overhead was positioned using a lubrication concept to manage the oil flow.
The oil reservoir is positioned above (not below) the geartrain. Oil is gravity-fed down onto the bearings and gears until it reaches the high-speed input at the bottom where it is then circulated back to the oil reservoir at the top. This minimises the amount of oil on the input shaft, keeping churning losses to a minimum. To ensure the critical areas remain lubricated even in disconnect mode, the motor is driven for brief, intermittent intervals to maintain a constant flow of oil.
The vehicle's tight packaging also means there is almost no air flow around the transmission; water cooling was needed to manage the heat generated by the module's high power density
GKN Driveline's president of engineering, Peter Moelgg said: "Being selected as Porsche's Technology Partner on the 918 Spyder programme was the perfect opportunity for our global e-drive team to demonstrate how putting the right technology on board can improve both fuel efficiency and dynamic performance. . . Our eAxle technology continues to evolve and we expect many more high-performance vehicles to adopt similar driveline concepts in the coming years."
