Yannis

Audi's new R8 road-going sports car, which incorporates the genes of the five-time Le Mans winning race car, will join the Audi TT in featuring Delphi Corporation's revolutionary MagneRide suspension technology.

Called Audi Magnetic Ride this innovative technology uses magneto- rheological fluid-filled dampers to provide continuously variable real-time suspension damping control. The system offers increased damper tuning capability, a very large range of damping, and faster response over valve- based controlled suspension systems. Audi Magnetic Ride delivers both maximum driving dynamics and superior road isolation that results in excellent driver comfort.

Furthermore, drivers can choose from two driving programs with a console- mounted two-position driver preference switch depending on whether they want to drive with maximum road feel and control, or with the emphasis more on ride comfort.

Principle of Delphi's MagneRide technology

Delphi's MagneRide semi-active suspension uses magneto-rheological fluid to provide continuously variable real-time suspension damping control. It responds in real time to road and driving conditions based on input from sensors that monitor vehicle body and wheel motion.

"The legendary success of the racing Audi R8 is well-known," said Daniel Warrell, Delphi Chassis Product Business Unit executive. "We are delighted to apply MagneRide to its road-going namesake."

Audi Magnetic Ride is based on a magneto-rheological principle. When in a magnetic field, small iron particles in the suspension fluid align themselves in the direction of the magnetic flux. The electromagnetic coil is integrated into the damper piston in such a way that when it is energized the magnetic flux runs exactly transversely to the admission ports in the damper piston. As the piston moves, the aligned iron particles cling together and create flow resistance in the flowing suspension fluid.

The greater the energy applied and the stronger the magnetic field, the greater the attractive force between the iron particles, thereby creating greater resistance and damping power. The energy is controlled in relation to driving dynamics and impulses from the road. This means for every road situation optimal damping power is available. This damping power produces -- according to OEM desire -- a more comfortable feel or sportier vehicle handling.

The control of these dampers is done by an electronic controller that communicates with the vehicle's sensors and other chassis controllers in order to determine the prevailing driving situation in a matter of milliseconds.

Application

Audi uses the magneto-rheological dampers for both comfort and sport. In its basic mode, the suspension allows for a more comfortable vehicle feel. In sport mode, the vehicle offers a more responsive ride thanks to a push of a button.

Because of the greater emphasis on ride comfort in the basic mode, maximum comfort is assured when driving over long distances or uneven surfaces.

The greater emphasis on precise and responsive handling in the sport mode results in even better control at the limit. It also optimally suppresses the transient rolling tendency of the car's body in corners.

Benefits

Because damper valving is eliminated by using magneto-rheological controlled fluid within the damper, the Delphi technology has a very short response time. The damping force is only dependent on the power applied to the magneto-rheological fluid and can be adjusted up to 1,000 times a second. Thanks to the nearly instantaneous and variable control of the power, the damping force can also be set anywhere in the broad range between the full soft and the full firm settings. This means the magneto-rheological dampers respond in real time and with great sensitivity to impulses from the road. The control system loop uses an enhanced Skyhook control strategy to ensure the greatest possible road-to-wheel contact on uneven road surfaces with the least impulse to the car body. This means that the new Audi R8 with Magnetic Ride has superb agility, great driving dynamics and outstanding ride comfort.

For Audi, the low-energy requirements of the system are another benefit. On average, a damper requires just 5 watts of electrical capacity (25 watts at a maximum).

Delphi's magneto-rheological monotube damper requires roughly the same space requirements as conventional dampers or struts. If required, Delphi can supply the complete semi-active system with dampers and struts including the sensors and the control unit.

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