Engineer: EV Wheels Housing Motors Ready to Roll

PARIS – Schaeffler and Ford engineers are building their second prototype of an electric vehicle whose motors are within the wheels. The first prototype, shown last spring, was based on a standard Ford Fiesta.

“The technology is all there now,” says Thomas Flebig, head of systems engineering on the project for Schaeffler. “It works. We are trying to bring it into production.”

To reach series production, he says, Schaeffler needs to bring down the cost of each part, conduct functional safety and environmental testing and document the technology for potential customers.

The eWheel project is being subsidized by the German government, which is encouraging pre-competitive co-operation to bring EVs to the market.

The €3.7 million ($4.8 million) MEHREN project (a German acronym that translates to Multimotor Electric Vehicle with Highest Room and Energy Efficiency) brings together the Ford Research Center in Aachen, Schaeffler, brake- and safety-systems manufacturer Continental Automotive, its Continental Teves unit and two German research institutes: RWTH Aachen and the University of Applied Sciences Regensburg.

Flebig says he works with 15 engineers and technicians and altogether Schaeffler has 40-50 people working on the eWheel.

While the Schaeffler engineer offers no details about the second prototype, it is likely to involve steering. For the first Fiesta, “we focused on driving normally,” Flebig says, noting the motors, one in each rear wheel, performed as expected.

A goal of the MEHREN project, according to its website, is to show that maneuverability can be improved. Adjusting the torque of each rear wheel to aid the front-wheel steering has some effect, but Flebig believes rear-wheel steering can be added, which could result in an extremely small turning   radius and even sideways parking. A third prototype is planned before the project ends in December 2015.

Another potential benefit of in-wheel motors is that a vehicle could be made smaller without losing passenger space. With the battery installed low below the floor, and the wheels replacing the internal- combustion powertrain, there would be no need for space under the hood.

Such motors have been patented since the beginning of the auto industry, and in recent years have been seen frequently on concept cars, including the General Motors Sequel and Mitsubishi MiEV (2005), Volvo C30 Recharge (2007), Heuliez Will and Protean Ford F-150 (2008) and Peugeot BB1 (2009).

In addition to Schaeffler, companies working on the idea include Hydro-Quebec, Protean and Michelin, which is working with Renault, microcar maker Aixam and several suppliers in a French consortium that is similar to the German project.

While some eWheel projects are aimed at hybrids, the Schaeffler project is for an EV. Application in a hybrid would save no space and add expense, says Flebig. Schaeffler believes the cost of two eWheels would be similar to that of an internal-combustion powertrain, but the cost of the battery still would make such a car more expensive.

Flebig says the Schaeffler eWheel differs mainly from the Michelin Motor Wheel in the size of the motor. Michelin’s is smaller, and uses a mechanical transmission to turn the wheel, while the Schaeffler motor turns the wheel one rotation for each of its own rotations. He says the Michelin approach may be less expensive, but it is noisier and suffers from energy losses in the transmission.

The eWheel uses a 16-in. wheel, but bigger ones could be made, Flebig says. Power electronics are integrated into the motor. The eWheel weighs 99 lbs. (45 kg), and the rim and tire add 17.6 lbs. (8 kg), but Flebig says the Fiesta suspension needed only to be tuned for the extra weight, not redesigned. Each motor produces 54 hp and 516.6 lb.-ft. (700 Nm) of torque. Software keeps the torque from damaging the tires, which for the first prototype were standard tires from Continental.