Electronic Shock Absorber Control

Assignment

One can recognise an optimum suspension/damping quite well by watching cars driving past on a bad road surface. The wheels should maintain the highest possible amount of road contact, whereas the car body should show the greatest possible calmness. Thus are also the demands placed on an electronic regulation. It selects the momentary characteristic curve which keeps the bodywork construction calm and steady during any given wheel movements.

Function

The pre-condition is the acquisition of the wheel- and car body movements. Because the wheels are able only to absorb impact in one direction, the car body however, can basically move in three directions, so four sensors are necessary. In this case, the direction as well as the momentary speed is noted. These values provide the damping-need in very small time units from a specific vehicle map. This is regulated through a proportional valve that can be seen at the bottom on the right of the above shown damper. The twin-tube damper shifts, when compressing or rebounding, damper oil from the inside into the space between, and vice versa. At this point the electrically operated valve starts to work. The hydraulic part of the valve is thus laid out, that the damping force (through-flow resistance) together with the control current sinks or rises. In case of an emergency, a mid-level through-flow resistance comes into play. The valve works in both directions likewise. Due to the the regulation speed it can nevertheless, adjust itself for the varying characteristic values of both compression and of rebound damping. 05/10