New
York 04/07/2004 -- The Acura RL Prototype, which makes its world debut today at
the New York International Auto Show, features a revolutionary new
all-wheel-drive system called SH-AWD(TM). The SH-AWD (Super-Handling
All-Wheel-Drive) system is the first and only all-wheel-drive platform that
distributes the optimum amount of torque not only between the front and rear
wheels but also between the left and right rear wheels. The result is precise
cornering performance that provides incredibly neutral steering and outstanding
vehicle stability.
By monitoring driver input and driving conditions, the SH-AWD system determines the
optimum front-rear and lateral (left-right) torque distribution. This
information is then conveyed to the rear differential, where direct
electromagnetic clutches continuously vary the front-to-rear torque by up to 70
percent in either direction. Rear torque can also be apportioned between the
left and right rear tires by up to 100 percent on either side.
The SH-AWD system is composed of an ECU, sensors that detect steering angle,
lateral g-force, and other vehicle information, and a rear differential. The
direct electromagnetic clutches inside the rear differential, another industry
first, employ electromagnets to maintain precise control over the multi-plate
clutches.
The SH-AWD system uses torque not only for propulsion, but also to increase
cornering precision and dramatically enhance vehicle maneuverability. During
cornering the speed of the outside rear wheel is greater than the average of
both front wheels. This prevents the efficient transfer of torque to the outside
rear wheel. To counteract this condition, the SH-AWD system's rear differential
is equipped with a built-in acceleration device that can overdrive the outside
rear wheel. This acceleration device, which is another industry first, uses a
planetary gear to speed up the outside rear wheel's rotation relative to the
front wheels. The result is a significant enhancement in vehicle maneuverability
during cornering.
SH-AWD system torque regulation
- Acceleration while cornering: Torque to the rear wheels is continuously
varied to supply up to 100 percent to the outside wheel. This creates an
inward yaw moment, significantly improving vehicle handling precision.
- Deceleration (throttle closed) while cornering: Torque to the outside rear
wheel is varied to change from an inward to an outward yaw moment, helping
vehicle stability at all times.
- Straight-line driving: Front-rear torque distribution is modulated for
optimum performance. During rapid acceleration, torque is redistributed from
the front wheels to the rear wheels. Conversely, during cruising, torque is
concentrated in the front wheels. The result is additional driving stability.
For media inquiries regarding the SH-AWD system or any Acura vehicle, please
visit www.acuranews.com.
