Overview
This document contains the following information:
General
Function requirement
Function triggers
Preventive occupant protection measures
Reversible emergency tensioning retraction
Seat adjustment (vehicles with seat adjustment with memory function)
Close sliding sunroof (vehicles with sliding sunroof or panoramic sliding sunroof).
Close side window, leaving a small gap.
Hearing protection
General
The approach of the preventive occupant protection system is to recognize potential risks of accident at their origin. For this purpose, various sensory capabilities are used, not least through the networking with driver assistance systems. In hazard situations, different actuators are actuated according to the situation in order to deploy their protective effect before the actual impact.
If the accident fails to happen, the fully reversible systems can be restored to their default positions and are immediately ready for operation again.
Depending on the equipment installed, the preventive occupant protection system can be extended by the following functions:
Rear collision warning system (vehicles with Driving Assistance Package)
Preventive occupant protection system for side impacts (vehicles with PRE-SAFE® Impulse Side)
Function requirement
Circuit 15 ON
Function triggers
The preventive occupant protection system defines the driving state based on the following parameters:
Vehicle deceleration
Wheel speed
Natural dynamics of the vehicle (yaw torque, lateral acceleration)
Steering angle
The following situations are classified as accident-critical:
Emergency braking: Rapid brake pedal operation (startle response).
Maximum full-stop braking: The driver's deceleration request is significantly greater than the physically possible vehicle deceleration (e.g. aquaplaning, ice or snow). Strong interventions of the anti-lock braking system (ABS).
Severe oversteer: Swerving of rear end combined with strong ESP® stabilization interventions.
Severe understeer: The vehicle pushes over the front wheels. Strong ESP® stabilization interventions.
Side wind stabilization: Drifting from the lane, combined with considerable amount of ESP® stabilization intervention.
Critical steering movements: Rapid steering at high speeds (startle response by the driver combined with excessive stress).
Secondary accident: The occurrence of another crash after an accident.
Vehicles with radar-assisted traffic area monitoring:
Strong brake force boosting by BAS PLUS: Risk of collision in linear and cross traffic.
Autonomous brake application by PRE-SAFE® Brake: Risk of collision in linear traffic.
Autonomous course correction by the blind spot monitoring system: Course-correcting brake application when there is a risk of collision with vehicles to the side.
Collision object detection at front/rear/side: Detection of an imminent collision.
The activation threshold for the preventive occupant protection measures is modified according to the following variables:
ESP® mode
Drive program (vehicles with automatic transmission)
Preventive occupant protection measures
The preventive occupant protection system activates the following measures for occupant protection in critical driving situations:
Reversible emergency tensioning retraction
Seat adjustment (vehicles with seat adjustment with memory function)
Position front passenger seat.
Adjust multicontour seat seat contour (vehicles with multicontour seats).
Close sliding sunroof (vehicles with sliding sunroof or panoramic sliding sunroof).
Close side window, leaving a small gap.
Hearing protection
All measures are deactivated as soon as the prevailing situation is no longer evaluated as critical.
Reversible emergency tensioning retraction
The reversible emergency tensioning retraction reduces the amount of seat belt slack by tensioning the front seat belts. The driver and front passenger are held in position better in their seats so as to optimize the protective effect of the conventional restraint equipment. Depending on the situation, the seat belt is tightened with varying force and speed.
As soon as the seat belt is fastened, the belt adjuster reduces the existing slack by tightening the seat belts. The function is available for the front seats. It can be switched on and off via the vehicle settings controls.
Seat adjustment (vehicles with seat adjustment with memory function)
The effectiveness of conventional restraint equipment is greater when the vehicle occupant is moved to an appropriate seated position. For this reason, the preventive occupant protection system commands the adjustment of the front passenger seat and, in the case of multicontour seats (vehicles with multicontour seats), the adjustment of the seat contour. An active setting, if given, is interrupted.
The following settings are made:
The front passenger seat is moved to a favorable position in terms of safety. Depending on the current seat position, the following adjustments are made:
Backrest inclination
Seat height
Seat fore/aft position
Seat inclination
The side inserts in the multicontour seats (vehicles with multicontour seats) are inflated. This fixes the occupant in the center of the seat.
The air cushions of the lumbar supports (vehicles with multicontour seat) are deflated. The occupant thus sits lower in the seat.
The adjustments are ended when the optimum seat position is reached. After completion or cancellation of the measure, the front passenger seat remains in the held position.
Close sliding sunroof (vehicles with sliding sunroof or panoramic sliding sunroof).
The sliding sunroof is closed completely by the preventive occupant protection system if it was open in the tilt position previously. If the sliding sunroof was previously open in the sliding direction, it is closed leaving a small gap. If the vehicle rolls over, for example, this ensures that no objects can penetrate into the vehicle interior and that no limbs of the occupants can protrude from the vehicle. After completion or cancellation of the measure, the sliding sunroof remains in the held position.
Close side windows, leaving a small gap
The side windows are closed leaving a gap of approx. 50 mm. This ensures that, during an accident, no objects can penetrate into the vehicle interior and that no limbs of the occupants can protrude from the vehicle. Furthermore, it allows the smoke particles arising from the activation of the restraint equipment to disperse quickly. Active window lowering (automatic) or a manual setting is aborted. When the side windows are closing, the automatic reversing function is active. If required, the closing process is reversed. After completion or cancellation of the measure, the side windows remain in the held position.
Hearing protection
During an accident, noises with high sound-pressure levels can be generated that damage the hearing. The output of a noise signal via the speaker system shortly before a possible accident prepares the occupants' hearing for the expected accident noise. The noise signal can trigger a natural reflex in the vehicle occupants that protects the eardrum against high sound pressure levels. This can reduce the harm to the occupants' hearing.
Function schematics | |||
Trigger preventive occupant protection system, function schematic | Model 213, 238, 257, 290 as of model year 2021 | ||
Model 118, 177, 247 with code 299 (PRE-SAFE) | |||
Model 167, 293 | |||
Subsystems | |||
Rear end collision warning system, basic function | Model 118, 177, 247 | ||
Side impact preventive occupant protection system, basic function | Model 167 | ||
Further basic functions | |||
Traffic area monitoring, basic function | |||
Actuate window lifter, basic function | |||
Open/close sliding sunroof, basic function | Model 118, 177, 247 | ||
Speaker system, basic function | |||
Front seat electrical seat adjustment, basic function | Model 118, 177, 247, 293 | ||
Multicontour seat,basic function | Model 118, 177, 247 | ||
Control units | |||
Electronic Stability Program control unit, basic function | |||
Reversible belt tensioner, basic function |