After a decade or so pondering how steering could be improved to enhance both maneuverability and cruising composure, Ford engineers have invented an ingenious Adaptive Steering system they hope to produce for sale in less than a year.
Ford's new guidance system changes the steering ratio according to car speed and wheel position. This is not the first addition of gears and an electric motor to help aim the front wheels—Audi, BMW, and Lexus are the notable pioneers in this area of technology—but it is the most clever arrangement we've experienced to date.
The beauty of the system is that the additional parts—a DC electric motor, a worm gear driving a helical gear at a 48:1 reduction ratio, two needle bearings, and an electronic control circuit—are housed totally within the steering wheel. To clear room within the wheel hub, development partner Takata engineered a more compact 'vacuum-packed' airbag module. The Adaptive Steering components add only two pounds to an eleven-pound steering-wheel assembly.
Responding to commands from a control circuit that monitors vehicle speed and steering-wheel position, the electric motor adds or subtracts up to 35 percent to the motion the driver imparts to the steering wheel. The lock-to-lock turns can be reduced from 2.6 (in a Ford Focus) to only 2.0. While the system is compatible with virtually every car and light truck in the Ford lineup, the first product that will feature this system is still a dark secret. Effort was invested in minimizing system friction and there is no lash between the worm-drive gears.
At low speeds and high turn angles—say, during a parking maneuver or when slaloming through traffic cones at a construction site—the helper motor adds steering lock so the driver's arms and elbows are less of a blur. Then at cruising speeds, steering response is diminished so lane changes are more fluid and napping passengers never bang heads. Adaptive Steering is compatible with both electric and hydraulic power assist, or, for that matter, no assist at all, although that option doesn't currently exist in Ford's lineup.
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A brief test drive in a Ford Fusion proved that the system works as expected. At this experimental stage, the ratio changes are barely noticeable—as intended—except in careful, concise A-to-B comparison runs. There is no significant addition of steering friction or loss of feedback (a sensation that's in very short supply these days in practically every manufacturer's vehicles). Ford engineers hope to provide a Sport setting that keeps the steering ratio quick—but not too quick—at high speeds for those rare drivers who keep both eyes on the road and two hands on the wheel.
from Car and Driver Blog http://ift.tt/nSHy27
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