Electric power steering is going mainstream. The system - used to save space on exotic sports cars or to boost fuel economy and performance on minicars - is headed for mass production worldwide.
With global cost-cutting and persistent high fuel prices, electric power steering makes sense. Switching from the common hydraulic system to electric can save automakers between $5 and $10 per car, estimates Rex Struble. He is product and business director for steering and suspension products for TRW Inc. in Livonia, Michigan.
The cost of an electric power steering system is about the same or slightly higher than a hydraulic unit. But automakers save money because they no longer have to assign engineers to adjust steering system feedback by designing and testing gears and valves. Electric power steering can be programmed to perform differently by changing the software. There are other cost-saving benefits. The electric steering system is assembled when delivered to the factory. An electric power steering system has fewer parts, which lets automakers stock less inventory. And assembly lines move faster because the fluid fill station is no longer needed.
SAVING ASSEMBLY LINE TIME
Delphi Automotive Systems Corp. estimates its E-Steer system shaves nearly four minutes off assembly time per vehicle. Delphi says the steering system parts count is reduced from 15 to two. Though an electric power steering system consists of a traditional rack-and-pinion, a 12-volt electric motor is mounted in the steering column near the firewall or down near the rack. The hydraulic pump, hoses, clamps, pulley, brackets and cooler are eliminated.
Fuel savings could range from .21 to .42 kilometers per 100 liters, says Brian Stainforth. He is an engineer in charge of electric power steering for Delphi in Troy, Michigan. The smaller the vehicle, the bigger the savings. Because a hydraulic steering system is connected to the engine with a fan belt, it draws power whenever the engine runs. Electric steering improves fuel economy because it draws no power until the driver turns the wheel. Sensors detect when the driver wants to change direction. Delphi says its E-Steer uses 3 percent of the energy of a hydraulic system.
Honda Motor Co. Ltd. introduced electric power steering a decade ago on the low-volume NSX sports car using a system by Showa Corp. Engineers wanted to save weight and needed space to fit the NSX's V-6 engine into a tight compartment behind the seats.
Besides reducing costs and raising fuel economy, electric steering has other benefits: improved safety and easier adjustability. Because electric power steering is not dependent on the engine, the power steering works even when the engine stalls.
Delphi's E-Steer system, available on the Fiat Punto in Europe since last year, lets the driver choose between city and highway modes by pressing a button on the instrument panel.
General Motors will be the first U.S. automaker to make the switch to electric power steering later this year in the new Saturn Vue small sport-utility. Koyo Seiko Co. will supply the system to Saturn Corp. Delphi will supply its E-Steer system to GM for a high-volume vehicle scheduled for production in the 2002 model year. And GM is to install electric steering in 2004 or 2005 in the next generation of the compact Pontiac Grand Am and Chevrolet Malibu. Ford Motor Co. and DaimlerChrysler say they have no plans to use electric steering before 2003.
POPULAR ON MINICARS
Electric power steering is popular in Japan, especially on minicars such as the Suzuki Alto, WagonR and Jimny. Daihatsu Motor Co. Ltd., Mazda Motor Corp. and Mitsubishi Motors Corp. also use the system. In Europe, Fiat Auto S.p.A., Renault SA, Volkswagen AG and Adam Opel AG have or will have vehicles that use electric steering.
TRW has 17 contracts for production or development of its system. Delphi has four contracts with three customers that could book the company $1 billion in sales in five years. Volkswagen plans to make Delphi's E-Steer optional on the Lupo later this year. Honda uses electric power steering on the NSX, S2000, Insight hybrid and Japan-market Accord. Robert Bosch GmbH, Koyo, Motorola Inc. and Showa also are manufacturing complete systems or electric steering parts. Siemens Automotive Corp. has an electric power steering system ready for installation, but no customers.
Struble, of TRW, says electric steering eventually will replace hydraulic power steering. 'It should make up between 40 percent and 50 percent of the market by 2010,' he says.
By that time, engineers should be ready to move power steering down another path: steer-by-wire. The mechanical link that connects the driver to the front wheels via a shaft will be gone. Instead, sensors in the steering wheel will send signals to electric motors to turn the wheels.
E-mail writer Richard Truett at [email protected]