adaptive break light

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Adaptive brake light (also called active brake light or dynamic brake light by individual manufacturers ) is a generally more noticeable second type of brake light for heavy braking in emergencies to inform the following traffic.

There are different types of adaptive brake lights or emergency brake indicators.

Adaptive brake light with emergency brake detection

This adaptive brake light is now used by various manufacturers. During "normal" braking, the brake lights light up like any other car, but during emergency braking the brake lights flash several times per second, e.g. B. at Mercedes-Benz 5.5 times per second. This warns the following traffic and, according to a study, shortens the reaction time. If the vehicle is braked to a standstill, the hazard warning lights switch on (on Mercedes-Benz, BMW , Renault and Volvo ).

A comparable system is used at Audi , Volkswagen , Seat and Škoda . In the event of severe decelerations from speeds of more than 60 km / h, the brake light flashes approx. 3 times per second. As soon as the vehicle is stationary, the brake light lights up continuously and the hazard warning lights are switched on.

The emergency brake light is regulated internationally - also in the EU - in the approval regulations. This in the regulations R-13H and R-48 of the UN-ECE in Geneva .

These say: Signaling via red or yellow flashing light from the rear of the vehicle. Switch on for delays over 6 m / s² and speeds over 50 km / h. Activate even if / as long as the ABS system is fully regulating.

Deactivation if: Speed ​​drops below 50 km / h If deceleration drops between 2.5 - 5.99 m / s². Freely selectable in this area. When ABS no longer fully regulates. These regulations apply from 2011.

If a manufacturer decides on an emergency brake light function, these regulations must be observed so that approval can be given.

There are also adaptive brake lights for retrofitting. It should be noted that the device should have official approval.

Emergency brake display through automatic hazard warning lights

With other manufacturers, e.g. B. Ford (before 2011), Mazda , Seat, Volkswagen and Renault, the following traffic is warned by automatically switching on the hazard warning lights in the event of an emergency braking.

The automatic hazard warning system is available for retrofitting. In the event of an emergency braking or an accident, the control unit automatically switches on the hazard warning lights and the raised hazard warning light (comparable to the third brake light) flashes at a higher frequency. The warning signal is switched off with the hazard warning light switch.

Adaptive brake light with two brake light surfaces

This adaptive brake light is partially used by BMW ; Since 2008, a brake light with emergency brake detection has been used on all new models. It does not differentiate (as with Mercedes) between "normal" braking and emergency braking, but between light (one brake light on each side) and strong braking - not necessarily emergency braking - with two brake lights (usually normal brake light and rear fog light) on both Pages is displayed. All the lights shine much brighter than when braking normally.

Emergency brake evaluation by the control unit

The control unit cannot recognize an emergency braking situation directly, but can only evaluate the physical parameters in order to control the signaling on the brake lights according to the assessed situation. In most of today's motor vehicles, a strong pressure on the brake pedal must have been carried out in order to initiate the special signaling. The following data can be evaluated by the control unit:

  • Actual (actual) and the desired (target) deceleration (determined from the pedal pressure)
  • Brake pedal operating speed or pressure
  • Intervention by ABS, ESP and possibly other brake assistants
  • Speed ​​of the vehicle
  • Static friction between the tire and the road

In order to exclude that dangerous situations - z. B. rear-end collisions due to unnecessary shortening of the braking distance for vehicles behind - caused by a false emergency brake display, the control unit must reliably detect emergency braking. Essential parameters for this, such as the distance to the obstacle, be it the vehicle in front or another suddenly occurring obstacle (children, animals or tractors) are not recorded in most of today's motor vehicles, so the available time and distance for an emergency braking can not be the control unit can be recognized and used for calculations.

literature

  • Karl-Heinz Dietsche, Thomas Jäger, Robert Bosch GmbH: Automotive pocket book. 25th edition, Friedr. Vieweg & Sohn Verlag, Wiesbaden, 2003, ISBN 3-528-23876-3
  • Robert Bosch (Ed.): Autoelectronics Autoelectronics. 5th completely revised and expanded edition. Vieweg & Sohn Verlag, Wiesbaden 2007, ISBN 978-3-528-23872-8