Motors in Wheel Give GM ‘Jump’ on Advanced Technology Vehicles

Engineers at General Motors Corp. have developed a potential breakthrough technology, called wheel hub motors, that could dramatically increase consumer acceptance of advanced technology vehicles.

“We believe this technology will lead to the industry’s first practical application of wheel hub motors for consumers,” said Larry Burns, vice president of research and development and planning of General Motors Corporation. “The electric wheel hub motor is a critical element in making affordable and fuel-efficient all-wheel drive and advanced technology vehicles in the future.”

“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.