DETROIT - Corrodible brake lines and paint-eating hydraulic fluid could fade into history if electronic brake-by-wire systems go into mass production.
Prototypes of such systems combine power braking, antilock braking systems and traction-control functions into one compact electromechanical package. Two were introduced last month at the SAE International Congress and Exposition by Continental Automotive Systems and Delphi Automotive Systems.
In dry systems, motors at each wheel drive the brake pads against the discs on command from a central computer, which dictates braking pressure based on pedal depression by the driver, speed, wheel spin and steering input. Conventional hydraulic calipers are eliminated.
The arrangement eliminates conventional hoses and brake hardware, such as the master cylinder and power brake booster, and allows greater control over brake modulation. The problem is that more electricity is required than cars currently carry on board.
Now, only the rear brakes of the General Motors' EV1 electric car use the technology.
However, Continental says it plans mass production in Europe by 2003, in collaboration with Siemens Automotive and Italian brake parts specialist Brembo SpA, says Martin Swoboda, vice president of marketing. He said the system will be lighter and more compact by then.
The development may be tied to another Continental product, a generator-starter motor that provides much more electricity than conventional systems. Citroen and BMW showed the system on engines at Geneva.
Before all-dry systems arrive, there are likely to be cars with partially dry systems which keep most of the hydraulic equipment.
Delphi's Galileo family of brake-by-wire products includes a wet system in which conventional hydraulic calipers are controlled by a central electronic pump. The design addresses the electricity problem of all-dry systems: The amount of power they consume is more than conventional 12-volt automotive electrical systems can support.
Bill Gillespie, chief engineer of advanced products for Delphi Chassis, says transitional brake-by-wire systems are needed to give customers, automakers and suppliers time to adapt to the new technology. Delphi is currently developing several designs to see 'which way customers want to go.'