Electronic Damping Control (explained) (archive)

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EDC is a fully automatic suspension damper (shock absorber) control system. It allows the driver the choice of two damping programs, Comfort (K) or Sport (S). EDC uses various input parameters directly relating to: (1) road condition, (2) load on the car and, (3) driving style to select one of 3 damping characteristics: soft, medium or firm. The results are optimum damping over a wide range of speeds and loads and gains in both ride comfort and safety. This is achieved by continuously matching the damping force to road conditions, vehicle and driving style.

The shock absorbers used on the EDC system are similar to conventional twin tube dampers, but have 2 solenoid valves each. These valves are held closed by spring pressure. This represents the firm setting with oil flowing through the piston and base valves. One of the damping valves is energized to open for the soft setting and the second valve is energized for the medium setting. The solenoid construction is identical for the soft and medium solenoids, though the soft solenoid has a larger orifice so more oil can pass through it.

The 2 position console mounted program switch enables the driver to choose between Comfort (K) and Sport (S) settings. When the Comfort (K) setting is selected, the priority is soft damping. Any changes to dynamic movement (while the car is in motion) are detected by 3 sensors (1. acceleration sensors that detect "bounce"; 2. road speed inputs that come from the car's speed sensor in the final drive; 3. a steering angle sensor which signals how far and how fast the steering is turned) will allow the system to switch to either medium or firm depending on how severe the changes are. The system will automatically switch back to soft setting when conditions warrant. This results in an ideal combination of maximum comfort and optimum driving responsiveness.

When the Sport (S) setting is selected, only the medium and firm damping settings are used. The control module selects the medium setting until dynamic changes require a higher damping force to maintain stability. The Sport program characteristics allow the firm setting to be automatically selected sooner and held longer than the Comfort program.

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