Koni gets active under the cab
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• The first semi-active dampers to appear on commercial vehicles could be used for cab suspension, says Koni bus and truck product manager Remco Ruiter. The company is well down the road in developing semi-active suspension for light vehicles and already has dashboardcontrolled versions on some high performance cars.
"Most truck buyers wouldn't pay the extra for semi-active suspension on the chassis, but there is scope for a simpler, cheaper system on the cab suspension", Ruiter insists.
Koni's semi-active suspension works on the "sky hook" principal: it's designed to keep the body from bouncing up and down without reference to what the wheels are doing, rather than using the body's mass to control the wheels.
By using accelerometers on each corner of the vehicle the system can work out the direction and acceleration of the body movement. Each constantly variable damper is controlled by the accelerometer and an ECU.
In town on smooth roads the damping is soft but it is automatically revised within 10 milliseconds when the vehicle speeds up, encounters bumps or bends, or brakes heavily. Such a system, which works on all the wheels and has a central ECU, is too expensive for most truck applications. However, a cab system could use a single accelerometer with no separate ECU.
Koni already makes a loaddependent damper for vehicles with air suspension but it says that a similar system for steel suspended trucks and vans is feasible.