Schaeffler unveils new four-wheel drive, battery electric vehicle
22 June 2011
Schaeffler has unveiled its latest electric vehicle concept, a four-wheel drive battery-electric vehicle (BEV) based on a Skoda Octavia Scout. The new ACTIVeDRIVE, which will be showcased for the first time at the Frankfurt Motor Show in September 2011, complements two other existing vehicle concepts from Schaeffler. This new trio of vehicles includes the ACTIVeDRIVE, the Schaeffler Hybrid and the CO2ncept-10%.
The innovation behind the ACTIVeDRIVE is its active electric differential (eDifferential), which is installed on both the front and rear axles. This component combines the electric drive with the option of wheel-selectable drive power control. This enables torque vectoring (torque distribution between the right and left wheel), which enhances driving dynamics, safety and comfort.
The eDifferential enables active intervention in driving dynamics via well-directed power supply – rather than braking intervention and therefore power reduction, as is the case with ESP (Electronic Stability Programme). The active electric differential significantly improves power transmission when driving on surfaces with different friction coefficients.
Furthermore, it assists steering and has a clearly positive effect on driving dynamics, safety and comfort. In addition, the use of two eDifferentials enables the longitudinal distribution of drive torques. The possibility of active longitudinal and lateral distribution of drive torque makes the eDifferential an ideal platform for innovative vehicle dynamics control systems.
Actively controlled torque distribution enables torque vectoring, which means that the vehicle can be controlled virtually without the use of steering and braking by using a wheel-selective flow of forces.
The eDifferential system integrates two water-cooled permanent magnet synchronous motors (PMSM) of different dimensions, a planetary gear, a gearbox for active torque distribution, and a central element: Schaeffler’s lightweight differential. The electric motors were developed by Schaeffler’s IDAM (INA Drives & Mechatronics) division.
The larger PMSM, which delivers up to 105kW and 170Nm, is the primary drive. The second PMSM controls torque distribution and is only required to deliver a 5kW output in order to generate up to 2,000Nm of torque difference to the axle.
Other novel features of the ACTIVeDRIVE include an integrated electromechanical parking lock; a new forced lubrication system for the gearbox that requires no oil pump; sheet metal planetary carriers; and various high speed, friction-optimised bearing solutions. The electronic controls for the ACTIVeDRIVE are supplied by AFT (Atlas Fahrzeugtechnik GmbH), Schaeffler’s automotive drive train mechatronics and vehicle testing division.
With two active electric differentials, the four-wheel drive ACTIVeDRIVE has an overall output of up to 210kW. Fitted in the cardan shaft tunnel, in front of the rear axle, are Lithium-ion batteries, which have a capacity of 18kWh. These function as energy storage devices for the vehicle.
The current 1,900kg test platform accelerates from 0 to 100km/h in just 8.5 seconds. The vehicle has an electronic maximum speed regulation of 150km/h. In this configuration, the vehicle’s cruise range is up to 100km.
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