Schaeffler, Ford Report Advances in Wheel-Hub Drive System
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Researchers in Europe say their second-generation electric wheel-hub drive system is simpler and more powerful than the first-generation technology they unveiled in 2010.
Developers at Germany's Schaeffler Group and Ford of Europe's Research and Engineering Center say their new architecture integrates power electronics, controller and liquid cooling within each wheel. That eliminates the complex vehicle wiring necessary in the original configuration.
Schaeffler's so-called E-Wheel Drive can deliver about 54 hp and an impressive 516 lb-ft of torque per wheel, according to Schaeffler. That's 33% more power and 75% more torque than the initial design.
The second-generation drive, which is being tested in an otherwise standard Ford Fiesta small car, weighs 117 lb. That means 85% more unsprung weight than a conventional wheel/bearing/brake assembly. Even so, developers point out, the system weight is significantly less than that of a conventional engine, transmission and half axles.
Ford project manager Roger Graaf says road tests show that fitting the hub drives to the rear wheels results in driving comfort and safety virtually identical to a conventional Fiesta. He notes that the hub-drive system enables wheel-by-wheel torque vectoring to enhance vehicle dynamics.
Hub drives are especially attractive for city cars because they eliminate the conventional powertrain and space required to house it. But fitting such systems to conventional small cars is only a first step. To maximize the benefits, a vehicle must be designed specifically for hub drive, says Schaeffler Chief Technical Officer Peter Gutzmer.