Overview
This document contains information on:
General
Function
General
The following components are integrated into the AIRmatic valve unit:
Level control valves (Left front level control valve, right front level control valve, left rear level control valve and right rear level control valve)
AIRMATIC central reservoir filling valve
AIRMATIC pressure sensor
Function
Level control valves
The adjustment of the vehicle level can be changed for each wheel using the level control valves.
When one of the level control valves is actuated, the AIRMATIC central reservoir and, where applicable, the AIRMATIC compressor can route air to the corresponding air spring to raise the vehicle level. If the AIRMATIC pressure reduction valve in the AIRMATIC compressor is operated simultaneously when the level valve is actuated, air can escape from the air spring and the vehicle level drops.
AIRMATIC central reservoir filling valve
The AIRMATIC central reservoir filling valve is required for filling the AIRMATIC valve unit or for filling the suspension struts with compressed air from the AIRMATIC central reservoir. If the air suspension control unit registers an insufficient pressure via the AIRMATIC pressure sensor while driving, the AIRMATIC compressor is switched on, the AIRMATIC central reservoir filling valve is actuated and compressed air is delivered to the central reservoir.
Once the required pressure is reached, the AIRmatic compressor is switched off and the AIRmatic central reservoir filling valve is closed.
The function is active as from a speed of v > 40 km/h (during acceleration) and up to a speed of v > 20 km/h (when braking).
The upper shutoff pressure for central reservoir charging depends on the current atmospheric pressure. The atmospheric pressure is received by the combustion engine control unit.
If the compressed-air stock is used to raise the vehicle, the AIRmatic central reservoir filling valve and the corresponding level valve are opened. At a certain pressure difference between the AIRMATIC valve unit and the air spring, compressed air escapes. The vehicle level is raised.
The level control valves are supplied via a common line.
AIRMATIC pressure sensor
In order to increase or reduce the central reservoir pressure if necessary, the AIRMATIC pressure sensor is used to monitor the central reservoir pressure.
The location of the AIRMATIC pressure sensor allows both the central reservoir pressure and the individual pressures in the air suspension bellows to be determined to match the actuation status of the level control valves.
Pressure determination taking the left front suspension strut as an example:
AIRmatic compressor off (de-energized)
AIRmatic pressure reduction valve closed (de-energized)
AIRMATIC central reservoir filling valve closed (de-energized)
Left front level control valve actuated (energized)