Siemens VDO visualises the electric wheel hub motor
August 13, 2006 Siemens VDO engineers are working on plans to integrate the drivetrain, steering, shock absorbers and brakes directly into the wheels of future cars. This concept, called eCorner, is claimed by Siemens VDO to be the basis for the ecological "Drive-by-Wire" automobiles which will become a common sight on roads in 15 years. eCorner replaces the conventional wheel suspension with hydraulic shock absorbers, mechanical steering, hydraulic brakes and, above all, conventional internal combustion engines. For car owners, Siemens VDO expects eCorner to translate into improved fuel mileage, more safety and greater convenience. Implementing eCorner would offer automotive designers far greater freedom to create future cars with an electric drivetrain and electronic control.
There are enormous requirements placed on tomorrow's vehicles. In the future, it will be vital to be as thrifty as possible with every drop of crude oil, making it necessary to find alternatives to large conventional internal combustion engines. As a result, Siemens VDO projects the traditional engine architecture will be replaced by electric wheel hub motors, which act directly on the wheels to accelerate the car. The four independently operating wheel hub motors will offer extremely dynamic driving on the future highway. The possible elimination of the internal combustion engines burning gasoline or diesel fuel will reduce emissions and will even satisfy the extremely strict laws being anticipated in the future. The Siemens VDO eCorner will make it possible to develop Drive-by-Wire vehicles on which the drivetrain, steering and brakes provide common support for the driver in critical driving situations, thus helping to avoid potential accidents.
The intermediate hybrid motors step
Although Siemens VDO will continue to invest in optimization of conventional internal combustion engines in an effort to completely exhaust their potential, the perspectives for the future are even more important. "Hybrid drives are only an intermediate step along the path to future propulsion solutions. We consider the electric motor to be the actual long-term drive solution for fulfilling even the most stringent emission laws of the future", stated Dr. Klaus Egger, Group Vice President of Siemens VDO Automotive.
eCorner combines drivetrain, steering, shock absorbers and brakes
In the future, car wheels will take on a different appearance than today's familiar steel or mag wheels. With eCorner, a tire containing a sensor (Tire Guard) for monitoring the inflation pressure will be in contact with the road. Even the wheels' suspension of the future will significantly differ from today's design. While complex mechanical wheel suspension systems with oil-pressure spring elements ensure a comfortable ride for the passengers and permanent, reliable contact with the road, electronic circuits will play an increasingly significant role in the future. Within eCorner, electric motors will take over the task of ensuring contact between wheel and road. With this new suspension, hydraulic steering can be eliminated, giving automakers new degrees of freedom. In the future, each individual wheel can be moved to its own specific steering angle. When the speed is reduced, the wheel hub motors act as auxiliary brakes using a generator effect. The energy reclaimed in this manner can be used to charge the vehicle battery. Finally, in addition to the generator brakes, the electronic wedge brakes (EWB) can decelerate each wheel separately with maximum precision and enormous braking power to match the need of the driving situation.
eCorner's drivers and automobile manufacturers advantages
The change-over from internal combustion engines to eCorner wheel hub motor concept will be enhanced by various aspects, for drivers as well as for automobile manufacturers, such as energy efficiency and the associated emissions. Under optimum conditions, a future full hybrid system utilizes approximately 85 percent of the theoretically available energy. Today's gasoline and diesel engines is even less than 50 percent. Wheel hub motors are projected to use up to 96 percent of the provided electrical energy for vehicle propulsion. This will make it much easier for automobile manufacturers to satisfy emission regulations and while simultaneously offering extremely dynamic vehicles with excellent fuel economy. Integration of various vehicle components into the wheels allows further modularization of future cars: Vehicle manufacturers only will require different drive wheel layouts for equipping highly differing vehicle concepts. Moreover, eCorner has the potential to allow a completely new vehicle design, when the large central engine with all its accessory parts and transmission are eliminated. Driver assistance systems using eCorner for support will offer drivers entirely new possibilities. Cars that can virtually park sideways using pivoting wheels or electronic steering aids and controlled acceleration of individual wheels for better vehicle stabilization in hazardous situations. Finally the costs for car owners will also be reduced: Fewer components and elimination of the hydraulic systems will reduce wear and service complexity.
On the way to eCorner
Siemens VDO believes the electronic wedge brake's start of mass production is an important milestone on the way to eCorner realization. The first car on public roads at the end of this decade with the Electronic Wedge Brake (EWB) will demonstrate the advantages of a completely electric brake system, opening the door for other elements to be integrated into the wheel. The greatest intermediate step toward eCorner will be the integrated corner module. During the next decade, this system will integrate all systems into the wheel with the exception of electronic shock absorbers and electronic steering. The combustion engine won't have to disappear completely for the time being: it will be able to provide the necessary electrical power for flexible long-distance vehicles.
For Siemens VDO, the Siemens AG network of innovation is the most important base for advancing eCorner's required technologies. This allows Siemens VDO's automotive engineers to utilize the experience of electric motor developers in the railroad sector or in the automation engineering field.
With its wide range of mechatronics and electronics products, Siemens VDO also is well equipped for the automotive future. With its modern systems, the automotive supplier will offer its customers ample freedom for optimization of internal combustion engines in the coming years. At the same time, the company is laying the cornerstone for reaching safe and emission-free cars of the future with the development of the eCorner.