Adaptive Suspension Dampinglink
Each air spring contains a fixed primary oil flow path that is internal to the damper. In addition, the dampers have a secondary, external oil flow path, which can be controlled in real time by electric solenoids. Rebound damping (wheel moving down from vehicle body) and compression damping (wheel moving up toward vehicle body) are controlled independently. As damping only resists motion – it cannot create force without motion. Adjusting damping does not move the vehicle up or down, it just affects how much resistive force the damper applies as the wheels move up and down relative to the body.
|
|
|---|
| Cross section of adaptive damper and solenoids |
Note
The valve shown here has slightly different construction from ours, namely with respect to the spring and solenoid plunger.
The adaptive air suspension system can be set to 4 different settings:
- COMFORT: provides a gentler ride for a relaxed driving experience
- AUTO: adjusts to a wide range of roads and driving styles, providing a fluid yet well controlled ride.
- SPORT: provides a firmer, more controlled ride that increases driver engagement and connection to the road.
- ADVANCED: Fine tune the suspension by dragging individual sliders to adjust Ride Comfort and Handling.
Note
Air suspension checks air spring pressure to estimate vehicle mass and adjust damping control accordingly.
Solenoid Valve Controllink
Each solenoid valve is pulse width modulation (PWM) controlled. By controlling the PWM voltage, the current through the solenoids is controlled. Current through the solenoid is inversely proportional to the oil flow through the solenoid. The higher the PWM voltage, the smaller the oil flow. This means that 100% PWM signal corresponds to a completely closed solenoid and therefore to a very stiff damping behavior. Also 0% PWM signal corresponds to a completely open solenoid and therefore to a very soft damping behavior.
Note
This means that when a solenoid valve connector is loose, or the wiring is compromised the damping behavior will be very soft, but even in this condition the vehicle is safe to drive and is completely controllable.
Continuous Controllink
Continuous control refers to “full state” damping. When continuous control is active, the system is functioning normally. Continuous control relies on multiple inputs to be fully functional (for example, height sensors, required CAN signal inputs, etc.).
End Stop Protectionlink
Tesla Air Suspension ECU uses ride height sensors to learn the distance to end of travel as the vehicle drives and encounters bumps and dips. Learned end stops are reset when
Ride height calibration is performed. As the damper approaches the end of travel, damper current is increased to make the damper stiffer and to soften the impact of bottoming or topping out.
