Ford Fiesta-based research car demonstrates in-wheel motors
The Ford Motor Company and automotive components specialist, Schaeffler have unveiled a Ford Fiesta-based 'eWheelDrive' car, a driveable research vehicle that could lead to improvements in urban mobility and parking by making possible smaller, more agile cars.
Powered by independent electric motors in each of the rear wheels, eWheelDrive technology offers space under the bonnet that in conventional cars is occupied by the engine and transmission, and in electric cars by a centrally located electric motor.
The design team believes this technology could in the future support the development of a four-person car that only occupies the space of a two-person car today. At the same time, eWheelDrive steering system designs could enable vehicles to move sideways into parking spaces – a potential breakthrough as cities become more populated and congested. Pim van der Jagt, Ford’s director of research & advanced engineering in Europe takes up the story:
“This is an exciting project to work on with Schaeffler because it potentially opens new options for the development of zero emission vehicles with very efficient packaging and exceptional manoeuvrability. Looking forward, we have the opportunity to scope out the vehicle’s capabilities and how we might overcome some of the challenges presented by implementing the technology.”
With in-wheel motors, the components required for drive, deceleration and driver assistance technologies are installed in an integrated wheel hub drive – including the electric motor, power electronics, controller, braking and cooling systems.
The output of each liquid-cooled, 360-420V wheel hub drive is 40kW. In its second (Beta) stage of development, it also delivers up to 700Nm of torque. Compared with the first-generation (Alpha) wheel hub drive, which was first exhibited in Schaeffler's Opel Corsa-based Schaeffler Hybrid concept car in 2010, the Beta version output is up by a third, and it delivers 75 percent more torque.
The drive has a total weight of 53kg, so there is a weight increase compared to a conventional wheel with a wheel bearing and brake of 45kg, and it outweighs its Alpha-generation predecessor, which still featured power electronics installed in the vehicle, by an additional six kilograms.
“Overall, we were able to reduce the vehicle weight once again”, explains Dr. Raphael Fischer, director of the wheel hub drives product group in Schaeffler’s eMobility systems division. “This is because, in addition to the liquid cooling, the power electronics and controller can now be integrated into the wheel, which means that the complex wiring in the vehicle can be omitted."
“This highly integrated wheel-hub drive makes it possible to rethink the city car without restrictions; and could be a key factor in new vehicle concepts and automobile platforms in the future,” says Schaeffler’s chief technology officer, Professor Peter Gutzmer. “For electric vehicles used in urban environments, which may become obligatory in many densely populated areas, the wheel hub drive makes previously unheard-of space savings possible.
“In these new vehicle concepts, all components that are relevant for propulsion, braking, and driving safety are housed inside the wheel,” adds Professor Gutzmer. “The vehicle platform therefore provides maximum space for passengers, luggage, and for the battery, electronics, and communication systems. And vehicle manufacturers can use this as a basis for a range of different body designs. Automobile manufacture originally started in just the same way.”
The Fiesta E-Wheel Drive development vehicle – designed in close cooperation with Ford Research & Advanced Engineering Europe – took time out of its otherwise tightly-packed testing schedule, including extensive test drives in the cold climate of Scandinavia, to make its first public showing at the ‘Auto, Motor und Sport’ conference in Germany.
“Excellent driving dynamics are among the main attributes of Ford vehicles, and our expertise and experience in this area has also been used during this project,” explains Roger Graaf, project manager at Ford Research & Advanced Engineering Europe. “The test drives have shown clearly that the driving behaviour of this test vehicle in terms of comfort and safety has remained at virtually the same level, despite the higher wheel-sprung masses compared to the conventional basic vehicle.”
In addition to regulating the stability of the driving dynamics, the two wheel hub drives also allow so-called torque vectoring - selective distribution of the torque to the wheels. Professor Gutzmer again:
“In this way, highly-integrated wheel hub drives also provide significant advantages in terms of manoeuvrability, driving dynamics, and active safety. The electric wheel hub drive therefore has the potential to become one of the drives of tomorrow and a valuable addition to the range of drives that, from a global point of view, will continue to be governed by increasingly electrified drive trains based on internal combustion engines.”
Ford joined the project, led by Schaeffler, to investigate the potential for future vehicles that could also offer zero emissions and more space for features such as additional protection zones. In-wheel electric motors are seen by many industry experts as a potentially important future technology enabler for city cars as the world becomes more crowded and urbanised.
It is projected that by 2050 the number of people living in cities globally will have increased from 3.4 billion to 6.4 billion*; and the number of cars worldwide will have increased fourfold.
“We face challenges that will have to be addressed through time, thought and investment,” says Sheryl Connelly, who oversees Ford’s future global trends research activities. “It is by starting to look at how we might meet those challenges through research projects such as eWheelDrive, that we ensure that we embrace a future of choice and not a future of constraint.”
Ford will next partner with Schaeffler, Continental, RWTH Aachen and the University of Applied Sciences, Regensburg, on project MEHREN (Multimotor Electric Vehicle with Highest Room and Energy Efficiency) to develop two new driveable vehicles by 2015. The project aims to increase the integration of in-wheel motors in a car and will look at vehicle dynamics control, braking, stability and – with a competitive marketplace in mind - the fun-to-drive factor.