Brake assist
A brake assistant is a brake booster in an automobile that ensures that the pedal pressure required to trigger emergency braking is increased to the maximum possible brake pressure in the event of an obvious (emergency) braking maneuver. The basis for this change in the brake boost characteristic is, among other things, the time between the last gas pulse and the actuation of the brake pedal (emergency braking) and the speed at which the gas pedal was released. Active activation of the brake assistant in this way by the vehicle driver distinguishes it from the emergency brake assistant , which carries out braking initiated by the vehicle's on-board computer . The anti-lock braking system (ABS) prevents the wheels from locking .
designation
These systems are called differently depending on the vehicle manufacturer or automotive supplier. B .:
- Daimler: BAS
history
The brake assistant is an important link in a chain of assistance systems, the development of which began with ABS. The traction control system (ASR, 1985) was initially based on ABS . This was followed by the automatic locking differential (ASD, 1985) and the automatically shifting four - wheel drive 4MATIC (1985). The Electronic Stability Program ESP (1995) also uses ABS signals. The brake assistant builds directly on the ESP range of functions. It eventually became the emergency brake assistant , which based on predictive sensors, adaptively pre-controls the braking system to prevent the crash, warns the driver optically and acoustically of an impending rear-end collision and, if necessary, actively decelerates the vehicle.
Function and mode of operation
Technically this is in the brake booster a partially evacuated chamber subjected to atmospheric air pressure, so the braking force gain that changes. Alternatively, this can also be done with hydraulics or mechanics. The triggering takes place via an electronic control.
Older methods use a sensor to measure the distance covered by the brake pedal in relation to the elapsed time and thus calculate the current speed and, if necessary, the acceleration of the brake pedal depressed. The sensor works on the potentiometer principle, i. H. the mechanical pedal travel value is assigned to an equivalent electrical value, which is then evaluated in the downstream ABS / ESP system.
Newer systems work in a similar way to the above, only that the sensor is not located on the brake pedal, but is built into the master brake cylinder .
Incorrectly initiated emergency braking is characterized in particular by braking maneuvers that start with a high brake pedal speed, but then decrease in intensity before the necessary brake pressure is reached (negative brake pedal acceleration). The BAS in the integrated ABS / ESP system recognizes this and then builds up the high brake pressure required for emergency braking in the master brake cylinder. Since the most important time during ABS braking is the beginning of braking with the highest possible brake pressure, the BAS can shorten the braking distance somewhat if the driver is braking too carefully.
The background to the introduction is the behavior of many drivers who do not react optimally in an emergency braking situation and do not initiate an emergency braking of the vehicle.
Legal situation
In the EU, the regulation applies that since November 24, 2009 all new types of passenger cars and light commercial vehicles had to be equipped with brake assistance systems as standard. Since February 24, 2011, this has been the case for all new vehicles.
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
Individual evidence
- ↑ "BAS" is under the registration number 2913139 as a brand ( classes 09 and 12) of Daimler AG entered
- ↑ Fuhrpark.de - EU makes brake assistants mandatory ( memento of the original from September 29, 2017 in the Internet Archive ) Info: The archive link was inserted automatically and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed January 6, 2010
