GF32.32-P-0002CA Adaptive Damping System (ADS), Function
GF32.32-P-0002CA Adaptive damping system (ADS), function
- with CODE (483) ADVANCED AGILITY package
General function requirements
^ Circuit 15 ON
The circuit status is sent by the electronic ignition lock control unit (N73) to the chassis CAN (CAN E).
Adaptive damping system (ADS), general
The adaptive damping system alters the damping characteristics of the dampers to match the selected driving style damping mode and the road surface condition. In doing so a choice can be made between a sporty or a comfortable suspension tuning.
The ADS consists of the following component functions:
^ Record function sequence for driving condition
^ Select function sequence for damping mode
^ Damper adjustment function sequence
Record additional function requirements for driving condition
^ Circuit 61 ON
The CDI control unit (N3/9) (on diesel engine) or motor electronics control unit (N3/10) (on gasoline engine) sends the circuit status to the chassis CAN.
Record function sequence for driving condition
The driving condition is defined through the following variables:
- Vehicle level and damping speed
- Vehicle body acceleration (chassis movement)
- Vehicle longitudinal and lateral acceleration
The vehicle level and damping speed are recorded by the following components:
- Left front level sensor (B22/8)
- Right front level sensor (B22/9)
- Left rear level sensor (B22/7)
- Right rear level sensor (B22/10)
The vehicle body acceleration is recorded by the following components:
- Left front body acceleration sensor (B24/3)
- Right front body acceleration sensor (B24/4)
- Left rear body acceleration sensor (B24/5)
The adaptive damping system control unit (N51/5) reads in the signals of the listed components directly. The vehicle's longitudinal acceleration and lateral acceleration is recorded by the yaw rate sensor for lateral and longitudinal acceleration (B24/15). The data of the yaw rate sensor for lateral and longitudinal acceleration are read in by the Electronic Stability Program control unit (N30/4) (except code (233) DISTRONIC PLUS) or by the Premium Electronic Stability Program control unit (N30/7) (with code (233) DISTRONIC PLUS) over the vehicle dynamics CAN (CAN H) and sent to the adaptive damping system control unit on the chassis CAN. The Electronic Stability Program control unit (except code (233) DISTRONIC PLUS) or the Premium Electronic Stability Program control unit (with code (233) DISTRONIC PLUS) sends information on the wheel speeds, brake status and braking torque through the chassis CAN to the adaptive damping system control unit. This information is used for computation of the vehicle speed and the probable chassis movement.
The adaptive damping system control unit also receives the following information over the chassis CAN, which is used for calculating the ideal damping stage or damping force at each of the dampers:
- Body variant from the front SAM control unit with fuse and relay module (N10/1)
- Steering angle and steering angle rate of change, recorded by steering angle sensor (N49), provided by the steering column tube module control unit (N80)
- Drive variant and kick down request (for transmission 722) from the CDI control unit or ME-SFI [ME] control unit
- Vehicle speed as substitute value from instrument cluster (A1)
Select function sequence for damping mode
Pressing the vehicle dynamics button (N72/1s23) on the upper control panel control unit (N72/1) enables a choice to be made between a sporty or a comfortable suspension tuning.
The status of the vehicle dynamics button is read in by the front SAM control unit over the instrument panel LIN (LIN 1) and it is sent over the chassis CAN to the adaptive damping system control unit. The adaptive damping system control unit receives the corresponding request and generates the required actuation signals for the actuators. If the "SPORT" mode is selected, the LED integrated into the vehicle dynamics button goes on. The adaptive damping system control unit sends the request for actuation of this LED over the chassis CAN to the front SAM control unit. The front SAM control unit actuates the LED in the vehicle dynamics button over the instrument panel LIN. If the vehicle dynamics button is pressed again for the "COMFORT" mode, the LED in the vehicle dynamics button goes off.
Additional function requirements for shock absorber adjustment
^ Circuit 61 ON
Function sequence, shock absorber adjustment
The input signals are used by the adaptive damping system control unit to determine each ideal damping stage and directly actuates the following components accordingly:
- Left front axle damping valve unit (Y51)
- Right front axle damping valve unit (Y52)
- Left rear axle damping valve unit (Y53)
- Right rear axle damping valve unit (Y54)
Implementation of the continuous damping adjustment is realized using twin-tube gas-operated shock absorbers. The damping valve units are located at the bottom side on the twin-tube gas-operated shock absorbers.
The main pistons and the bottom valve of the twin-tube gas operated shock absorbers each have a check valve integrated into them. These check valves ensure that an identical flow direction is given through the damping valve unit, both in the rebound and the compression stages. This design enables the damping valve unit of a shock absorber to consist of a single regulated proportional valve only.
The flow area in the damping valve unit can be continuously adjusted through actuation of this proportional valve. More or less oil can flow through the damping valve unit to match the set cross section. The damping behavior then becomes correspondingly softer or harder.
