Rollover protection system
The rollover protection system is an active safety system for convertibles and roadsters .
In vehicles with a fold-out roll bar or extendable rear headrests, an electronic triggering device (rollover sensor) allows the rollover protection devices to deploy in the event of vehicle rollover, whereby a strong electromagnet unlocks a pretensioned spring. Since a rollover can occur in any horizontal direction, the rollover sensor must react in every direction.
Tripping
The rollover sensor detects a vehicle rollover due to vehicle acceleration, vehicle inclination and rear wheel deflection or lifting of the vehicle ground. The acceleration is recorded by an acceleration sensor in the longitudinal and transverse directions of the vehicle for all directions. A microcomputer squares and adds the sensor signals and compares the resulting acceleration with the programmed trigger threshold of approx. 5 G. A tilt switch evaluates the vehicle tilt as a second trigger criterion. As soon as the inclination reaches or exceeds 27 ° and at least one of the two rear axle switches has opened as a signal for a rebounded rear wheel, the roll bar is also triggered. The microcomputer and an analog hardware path evaluate the second trigger condition redundantly in order to increase functional reliability.
More functions
In addition to the triggering functions, the rollover sensor performs a self-diagnosis that checks the external actuators, the rear axle switch, the on- board power supply and the warning lamp. It has a non-volatile error memory , an error clock and a serial diagnostic interface. When triggered, the central locking is opened. Other rollover or overturn detection concepts ( BMW / Te-mic) use bubble sensors inclined towards the vehicle axles ( spirit level principle) to determine the angle ( roll angle > 52 °, pitch angle> 72 °) or a gravity sensor that closes a reed contact with spring support when the ground is lost to detect rollover .
outlook
With an increasing degree of equipment in vehicles with airbags (standard in Europe up to the turn of the millennium), the quality of the sensor technology and the triggering mechanisms as well as the number of protective functions will continue to increase:
- "Smart bag" (adjustment of the trigger and inflation of the airbag on the occupant position of accident Gurtbenutzung, temperature, etc.)
- Integration of front, side impact and rollover detection in a central combination device that activates all protective devices, detects passenger and child seat occupancy and determines atypical vehicle positions,
- Networking of the multifunction device via a bus with drive train electronic devices (e.g. switching off the fuel pump after a crash) and
- Networking with ABS / ASR and dashboard display systems for clear driver information about the type and location of the fault.
See also
source
- Robert Bosch GmbH , Automotive Handbook , 22nd edition, page 757