Air Suspension Featured on Land Rover Discovery 3 (LR3)

Technology helps provide exceptional blend of on- and off-road performance

New materials and manufacturing processes meet challenging targets

LUTON, United Kingdom, Sept. 23 -- Innovative air suspension technology is helping Land Rover combine the legendary off-road ability of its vehicles with exceptional refinement and driving dynamics. A key part in the development of the airspring modules was played by Delphi Corp , which manufactures the units at its facility here. The new technology will be available on the Discovery 3 (called LR3 in North America), launched at the Mondial de l'Automobile show in Paris today.

"The Discovery has always had an outstanding reputation for off-road ability, which had to be maintained with the new vehicle," said Guy Hachey, Delphi vice president and president, Delphi Energy & Chassis. "The challenge was to combine this with levels of suspension refinement that would normally be expected in conventional luxury vehicles."

Land Rover also set tough targets for packaging, durability and the air spring's ability to maintain vehicle trim height, even when left fully laden for long periods with the engine off. The packaging requirement dictated the use of small volume air springs, which made the refinement target more challenging because the smaller air volume drives very high internal operating pressures, introducing the possibility of suspension harshness.

The vehicle's ability to travel quickly on poor surfaces presented further challenges because air springs have a natural tendency to become stiffer under low amplitude / high frequency road inputs, again potentially leading to suspension harshness.

The technology chosen uses front and rear airspring modules with integral twin-tube gas dampers, controlling the vehicle's four-wheel independent suspension. Delphi's engineers developed a new generation of compact, very high-pressure airspring units and new manufacturing and testing techniques to provide consistently high quality.

The new airspring modules allow Delphi to meet the packaging targets and, compared with conventional coil springs, weigh about 7 kg less. The units are designed to withstand the most demanding burst pressure and temperature range requirements set by any vehicle manufacturer.

The new design of airsleeve is constructed of soft, thin rubber reinforced with nylon chords: a construction chosen to minimize suspension harshness. An aluminum restraining cylinder is placed around the airsleeve to give it rigidity, increase durability and allow it to resist very high pressures. Protection from mud and stones is provided by a rubber gaiter.

During the design processes, Delphi engineers paid particular attention to component sharing between front and rear units and to design-for-manufacture, allowing faster development and reducing both development and manufacturing costs. Final calibrations were supported by Delphi's mobile 'ride laboratory,' which allows the specification of components such as dampers, air springs, spring aids, and top-mounts to be quickly changed and evaluated on the vehicle.

Several new manufacturing and quality control processes were developed to provide that the units will withstand the very high pressures required. More than 35 in-line tests confirm critical stages of assembly, including two high- resolution laser gauges accurate to just 0.001mm. At the end of the production line, a custom helium leak test system is used to verify the performance of every unit before delivery to Land Rover's plant in Solihull, United Kingdom.

As well as enabling an outstanding combination of on- and off-road ability, the air suspension system provides automatic self-leveling, regardless of the mix of passengers, cargo or trailering requirements, the ability to change the ride height for increased ground clearance or to improve the approach and departure angles for off-road driving, and the ability to lower the vehicle to ease loading or for trailer attachment.

Other Delphi technology on the Discovery 3 (LR3) includes Delphi's Smart Cruise Control system to increase comfort on long journeys, an advanced airbag system, a high-durability lead / calcium battery and a carbon canister for the emissions control system.