|Schaeffler’s eDifferential provides drive power for the vehicle as well as allowing power distribution between the wheels on an axle. Click to enlarge.|
The Schaeffler Group, a leading global supplier to the automotive industry, used the North American International Auto Show (NAIAS) in Detroit to highlight a number of hybrid solutions and electric mobility products as well as products for optimizing conventional drivetrains based on the internal combustion engine.
The Schaeffler eSolutions concept model at NAIAS showcased technologies such as the eWheel Drive electric wheel hub drive and the eDifferential—an electric axle that allows both the specific distribution of the drive torque to individual wheels and torque vectoring to provide enhanced driving dynamics in electric and hybrid vehicles. Schaeffler has applied these and other eMobility technologies in a trio of on-the-road concept vehicles: ACTIVeDRIVE, the Schaeffler Hybrid (earlier post), and the combustion-engine oriented CO2ncept-10%.
eDifferential. The active electric Differential, mounted on the front and rear axle, is the main innovation in Schaeffler’s ACTIVeDRIVE concept, which is based on a Skoda Octavia Scout.
The eDifferential integrates two water-cooled permanent magnet synchronous motors (PMSM) of different dimensions, a planetary gear, a transmission for active torque distribution and, as a key element, a Schaeffler lightweight differential. The electric drives are manufactured by Schaeffler brand IDAM. The larger PMSM (up to 105 kW and 170 N·m ) provides the drive. The second PMSM, which regulates the distribution of torque, must only supply 5 kW of power in order to generate a difference in torque on the axle of up to 2000 N·m.
The other innovations incorporated in the ACTIVeDRIVE are an integrated electromechanical parking lock, a new force-feed lubrication system without an oil pump for the transmission, planet carriers of sheet metal and various high-speed bearing solutions with optimized friction characteristics. The electronic control system is manufactured by AFT and is therefore also a Schaeffler product.
Due to the use of two active electric differentials, the concept vehicle has an overall output of up to 210 kW (281 hp) and features four-wheel drive. Li-ion batteries located in the propshaft tunnel and in front of the rear axle with a capacity of 18 kWh function as energy stores. Thanks to its performance and traction capacity, the test platform, which weighs 1,900 kilograms, accelerates from 0 to 100 km/h in 8.5 seconds. The vehicle features electronic top speed regulation at 150 km/h (93 mph). The vehicle’s range in this configuration is up to 100 kilometers (62 miles).
|Schaeffler eWheel Drive. Click to enlarge.|
eWheel Drive. The eWheel Drive features in the Schaeffler Hybrid, which combines a volume-produced combustion engine from a basic vehicle, and a central electric motor along with two wheel hub motors.
The various elements can each be switched on and off and incorporate a wide range of various driving conditions. These options range from classic operation using a combustion engine, operation as a parallel hybrid or serial hybrid to operation using the electric motor only. The combustion engine can power the vehicle and be coupled for use as a range extender. An automated manual transmission increases the options available.
The energy store, a 16 kWh lithium-ion battery (400 V, 400 A), is charged by means of energy recovery; the range extender; and by an external power supply (plug-in hybrid).
The central electric motor unit is flange-located to the automated manual transmission by means of a toothed chain and drives the front wheels. The unit comprises a liquid-cooled 50 kW, 95 N·m electric motor designed and manufactured by Schaeffler subsidiary IDAM.
The second-generation motors in the two eWheel Drive units have an output of around 70 kW each and torque of around 700 N·m. Schaeffler profits from its expertise in the field of wheel bearings and direct drive technology during the design and manufacture of these high-performance components. The wheel hub motors form a compact unit that integrates wheel bearing, drive and brake.
Schaeffler is also contributing to increasing the efficiency of vehicles with conventional drivetrains.
After all, the majority of all automobiles in the future will still have internal combustion engines serving either as the single or primary drive source, or as a range extender. These internal combustion engine drivetrains still have a great deal of room for improvement in terms of fuel consumption and CO2 emissions—up to 30% in practice.—Prof. Peter Gutzmer, member of the executive board and chief technology officer
This potential can be achieved by optimizing the thermodynamics, minimizing pump losses and frictional resistance, using ancillary equipment controlled according to requirements, improving targeted thermal management, downspeeding, downsizing and optimizing the start-stop function. Schaeffler also showcased innovations in torque converter technology, a thermal management module and components for variable valvetrains at NAIAS.