GF91.25-P-2002RI Adjust Front Multicontour Seats, Function

GF91.25-P-2002RI Adjust Front Multicontour Seats, Function
- with CODE (404) Driver seat multicontour backrest
- with CODE (405) Front passenger seat multicontour backrest as of Model Year 09/YoM 08 model refinement package

Function requirements, general
^ Circuit 15R or circuit 15 ON
^ Pressure supply active

Adjust front multicontour seat function, general
The right front multicontour backrest switch group (S108) or the left front multicontour backrest switch group (S109) can be used to individually adjust the contours and the surface hardness of the backrest on the multicontour seat by inflating and deflating the air cushions.

The air cushions are located as follows:
- in the lower lumbar area,
- in the upper lumbar area,
- in the left and right side bolsters of the backrest,
- in the shoulder area of the seat backrest,

The pneumatic controller unit with combined functions (A37) ensures the air supply required to inflate the air cushions.

The Adjust front multicontour seat function is described on the driver seat for left-hand drive vehicles by way of an example, but this also applies for the front passenger seat.

Abort conditions
- Leak in an air cushion with the corresponding function
- On-board electrical system emergency operation mode,
- the corresponding channel of the front multicontour backrest switch group has a short circuit to ground or is jammed.

Blocking
When the following fault is active, the function is locked for the current ignition sequence:
- The corresponding channel of the front multicontour backrest switch group has a short circuit to ground or is jammed.

In the event of valve overtemperature, the affected function is also shut down.

The "Adjust front multicontour seats" function enables the following subfunctions:
^ Adjustment of the air cushion side bolsters
^ Adjustment of the air cushions of the shoulder area
^ Up/down adjustment of the lumbar support
^ +/- adjustment of the lumbar support
^ Deflating functions
^ Short-term and long-term control

Adjustment of the air cushion side bolsters
The right and the left lateral support air cushions can be inflated together up to a maximum pressure when the side bolsters adjustment switch (S109s2) is pressed "towards the inside" and deflated to a minimum pressure when it is pressed "towards the outside". In doing so, the pneumatic valve is opened after the minimum residual pressure of 15 mbar is reached for no longer than 60 s (upon actuation).

Maximum pressure for each cushion: 500 mbar

The actual/maximum pressure values of the air cushions are read in via piezo-resistive pressure sensors by the left front multicontour backrest control unit (N32/15)/right front multicontour backrest control unit (N32/16).

Adjustment of the air cushions of the shoulder area
The air cushions in the shoulder area of the seat are adjusted with the shoulder area adjustment switch (S109s4). When the rocker switch is pressed towards "+", the backrest contour in the shoulder area changes as the air cushions are inflated. When the rocker switch is pressed towards "-", the backrest contour in the shoulder area changes as the air cushions are deflated. In doing so, the pneumatic valve is opened after the minimum residual pressure of 15 mbar is reached for no longer than 60 s (upon actuation). Maximum pressure for each cushion: 300 mbar

Up/down adjustment of the lumbar support
The air cushions are manually adjusted by inflating or deflating them using the lumbar support adjustment switch (S109s3). As long as the cross-shaped rocker button is pressed towards "up arrow", the backrest contour in the lumbar area changes through deflating the lower air cushion and inflating the upper air cushion. As long as the cross-shaped rocker button is pressed towards "down arrow", the backrest contour in the lumbar area changes through deflating the upper air cushion to minimum wave pressure. Next, the lower air cushion is inflated.

All air cushions are deflated for a maximum of 60 s.

+/- adjustment of the lumbar support
As long as the cross-shaped rocker button of the lumbar support adjustment switch is pressed towards "+", the backrest contour in the lumbar area changes through inflation of the currently active upper or lower lumbar air cushion. On reaching the maximum pressure, the inflation is stopped.

As long as the cross-shaped rocker button is pressed towards "-", the backrest contour in the lumbar area changes through deflating the currently active upper or lower lumbar air cushion. In doing so, the pneumatic valves are opened after the minimum residual pressure is reached for no longer than 60 s (upon actuation).

Maximum pressure for each upper lumbar cushion: 150 mbar
Maximum pressure for each lower lumbar cushion: 200 mbar

Deflating functions
The cushions in the lumbar area are overlapping, and thus their function is linked during the wave sequence. Since only one air cushion is active, the adjacent cushions are considered not active (empty).

The following deflating functions are required to ensure this:

Idle time deflation
While pressure is maintained in the active air cushion (dwell time), the adjacent non-active cushions are deflated.

Background deflation
If an active air cushion is deflated, then the residual pressure in the adjacent non-active air cushions is also reduced, as soon as the air cushions exhibit the same pressure.

Limit stop deflation (deflation time out)
If, following the wave cycle towards "-", the limit stop is reached, then the residual pressures in the air cushions for each area are reduced, as long as the cross-shaped rocker button continues to be pressed towards "-", but not for longer than 60 s.

Short-term and long-term control

Additional function requirements
- no adjustment active
- no pulse function (massage function) active

The short-term control compensates for overpressure deviations in the air cushions. It activates following every adjustment and only remains active for a shorter parameterizable period of time. This function is used among others to compensate for sitting down or leaning back immediately and in a comfort-oriented fashion. After the short-term control, the long-term control becomes active. Here, the pressure supply is regulated such that the specified pressure is always achieved. This is done almost without the customer noticing.