"To illustrate the promise of this technology, by placing two wheel hub motors, in the rear of a front-wheel drive four-cylinder vehicle, there will be a 60 percent increase in torque at the launch. All of that torque is available instantly. This enables a four-cylinder engine to perform like a six-cylinder engine, " Burns said.
The two-wheel hub motors generate about 25 kilowatts each and only add about 15 kilograms to each of the rear wheels.
With today's vehicles, engines create rotating power, or torque. That energy is transferred to a set of gears, or a transmission. The gears turn a drive shaft and ultimately spin the wheels. More than 10 percent of the power created by the engine is lost transferring energy to the wheels.
GM's system is different. A hybrid electric vehicle generates electric power, which is sent directly to the motor at the wheel, minimizing the energy lost. Conventional engines take time to get up to speed. With wheel hub motors, all the torque is available immediately.
"Picture a world-class sprinter that comes out of the starting block in less than half the time, using less energy. That's what 60 percent more torque, created by wheel motors, can do for a vehicle," said Burns. "This breakthrough technology may enable us to build some pretty exciting future vehicles that have the potential to be as quick as a sports car, while providing significant fuel economy improvements."
Wheel motors are a natural tie-in to all-wheel drive, and they enable a higher level of traction and anti-skid control, improved steering and enhanced vehicle performance. Towing might even be easier with wheel hub motors.
When packaged in a truck, wheel hub motors improve the truck's performance off-road and enhance the all-wheel-drive capability, added Bill Slomski, managing director of GM's Advanced Technology Center in Torrance, which developed the technology.
"The wheels don't slip," Slomski said. "We have the ability to control each individual wheel with better response than today's high-end traction control systems. That could be a real plus when your vehicle is stuck in deep snow or the pavement is real slick. We can apply the traction to the tire that has grip."
Slomski can imagine a day when a truck would have the maneuverability of Michael Jordan doing a 360-degree dunk. Tires could turn at 90-degree angles in a parking lot, making it simple to park. To demonstrate the wheel motors, GM engineers integrated the wheel hub motors into a S-10 electric pickup. The first public demonstration was at Irwindale Speedway today in Irwindale, Cailf.
The wheel hub motors were made by Lucchi R. Elettromeccanica Srl, in Rimini, Italy, and developed by GM's Advanced Technology Center based in Torrance, Calif. Quantum Technologies (Nasdaq: QTWW), of Irvine, Calif., built the concept truck, modified the vehicle's coolant, power and electrical systems and developed the special electronic controller and related software. Quantum is best known for its work in compressed storage tanks for natural gas and hydrogen as well as developing technologies for a variety of alternative fuel vehicles. GM owns 20 percent of Quantum.
(August 11, 2003)