Around The eCORNER

Siemens VDO integrates the drive, steering, braking, and suspension functions into wheel modules for greater efficiency and safety.

Is the traditional internal combustion powertrain dead? Will conventional steering, suspension, and brake systems follow? Certainly the folks at Siemens VDO (Auburn Hills, MI; believe their days may be numbered. Though the company is continuing to invest in optimizing internal combustion engines, it has started developing the core technologies necessary to move its "eCorner" concept from idea to reality.

Believing that drive-by-wire systems and what they term "ecological" vehicles are just 15 years away from volume production, research has begun at Siemens VDO on an integrated wheel module that combines drive and dynamic functions. Though these technologies can be integrated into vehicles powered by an internal combustion engine or a hybrid powertrain, Dave Royce, director, Corporate Strategy, Siemens VDO says, "Under optimum conditions today's gas and diesel engines use less than 50% of the theoretically available energy for vehicle propulsion. Future hybrid systems will raise that to 85%, but wheel hub motors will use 96% of the available electric energy to drive the vehicle."

Each eCorner unit includes Siemens VDO's electronic wedge brake, a wheel hub motor, and electronic motor-driven dampers. "Our goal is to keep the unsprung mass below 20% of the total wheel weight, reduce the overall weight of the vehicle, and keep the total weight of the modules below that of the traditional components we're replacing," says Royce. Uncooled wheel hub motors with approximately 150 Nm (110 lb-ft) of torque would give up to 600 Nm (440 lb-ft) of torque at the wheels in an all-wheel-drive application, though switching to cooled motors would raise this to a total of 1,000 Nm (738 lb-ft), if required.

"We expect initial applications to be two-wheel-drive only," says Royce, which will give automakers a choice of which end of the car to drive without having to design, develop, and produce different chassis and driveline components. And while Royce agrees that an eCorner module will be much more expensive than a road wheel alone, he says its greater dynamic capability will prevent enough accidents to reduce overall vehicle ownership cost. "There is greater safety with this system because of the enhanced dynamic function that allows us to do things like accelerate or steer each wheel independently, and integrate these functions with independent control of the dampers and brakes," he says. "Plus, we can reduce the overall price by integrating different functions, speed up development times, and reduce vehicle complexity."

Suppliers are likely to buy the components from Siemens VDO and integrate them into a completed module that is delivered to the assembly line, and Royce is certain the technology will change the way cars look and feel. "The steering column and transmission will disappear, and there will be more space for passengers and their luggage," he says. "We'll see some very futuristic designs made possible by this technology."