Attempts to introduce fully adaptive suspension systems into the volume car market have so far had limited success. For most customers they remain an expensive upgrade, even on many premium models. It seems that buyers of smaller cars want the benefits of improved car control and superior passenger comfort, but are wary of paying a premium for the technology.
Specialist chassis system supplier BWI Group, which works with carmakers including Ferrari, Audi, MINI and Land Rover, has been applying its considerable engineering resources to the issue. The company claims to have developed a more intelligent passive damper that could allow carmakers to offer more of the functions found in adaptive suspension systems. This, and some useful weight savings that help improve dynamics and CO2, is leading to interest from manufacturers of B, C and D-segment models, the company reports.
Frank Robinson, BWI Group’s Product Line Director for Suspensions says: “BWI’s work on valve design has extended the range of passive dampers’ performance, providing more of the functions associated with adaptive dampers at lower cost and weight. As a result the compromises in our new dampers are fewer: the driver has more control while passengers enjoy greater comfort.”
These smarter valves in BWI’s dampers generate multiple damping curves that allow the suspension to react appropriately to different input amplitudes and speeds. The dampers can then deal more effectively with different road conditions, such as pot-holes and speed-bumps. They can also better protect the vehicle structure from large impacts: on harsh terrain, the valves also help reduce the shocks transmitted to rubber mounts and limit-stops that could otherwise be damaged.
The range of dampers also includes a series of mass reduction measures. BWI Group says that industry efforts to reduce weight, usually from the sprung mass, can compromise a car’s handling unless an appropriate ratio between sprung and unsprung mass is maintained. Lighter vehicles need lighter dampers, basically.
By using structural plastics instead of metal brackets and spring seats, by varying the wall thickness of the steel damper tube, and by using hollow piston rods, BWI is able to reduce typical damper weight from 4kg to 3kg, without resorting to costly aluminium solutions. “This corresponds to a possible saving of 4kg per vehicle on a typical C-segment car, equipped with front and rear McPherson strut suspension,” says Robinson.
The shift in the market towards small premium cars is making it more important to provide improved ride and handling more cost-effectively. BWI Group is positioning its range accordingly; other suspension suppliers are likely to follow.