Seat occupied recognition sensor with automatic child seat recognition, function - GF91.60-P-4008-03PP
Seat occupied recognition sensor
The front passenger seat occupied and child seat recognition sensor (B48) consists of the metal foil strain gauges (pressure sensors), the transmitting and receiving antennas and the electronic analysis system. The pressure sensors form a corresponding resistance signal depending on the weight applied. The electronic analysis system differentiates between whether this refers to a punctual occupation (e.g. shopping bag, box or case) or a surface occupation (e.g. passenger). The resistance signals of the pressure sensors are initially detected and evaluated by the electronic analysis system. If there is an occupied signal, this is immediately sent to the restraint systems control unit (N2/7) in the form of a digital log for activating the front passenger safety devices. The state of seat occupancy is detected again every 2.5 s. After the load on the front passenger seat has been removed, the occupied signal is retained for a further 2 min. The signal is retained to prevent immediate shutoff of the safety devices if the load on the front passenger seat is removed for a short period.
Automatic child seat recognition
The function of the automatic child seat recognition is only ensured with a special type of child seat offered as an MB accessory. The child seat must have a transponder for communicating with the inductively operating automatic child seat recognition in the front passenger seat. MB child seats are equipped with 2 transponders each. To detect the child seat, the electronic analysis system inductively excites the transponders via the front passenger seat occupied and child seat recognition sensor (B48). The transponders alter the transmitted signal and send it to the two assigned receiving antennas in the sensor mat. The electronic analysis system breaks down the transponder signals and signals the installed child seat to the restraint systems control unit (N2/7) in the form of a digital log.
The different coding of the two transponders enables the electronic analysis system to recognize the installation position of a child seat. This information is currently insignificant because the front passenger airbag is always deactivated when a child seat is installed, irrespective of the installation position.