Electronic brakeforce distribution

Electronic brake force distribution (English Electronic Brake Force Distribution, EBD ) is a system for the stabilization of motor vehicles.

Principle

During heavy braking, the vehicle weight is transferred to the front wheels. As a result, the rear wheels lock as they are released and the brake power can no longer put on the road by the reduced ground contact. In this case threatens immediate danger of skidding (see oversteer).

A weighting of the braking force is achieved in part by the fact that the front brakes are designed to be stronger, that is to say brake harder with the same pedal pressure than the rear. Since, however, runs the stopping power of the rear wheels reverse to the delay, another mechanism is needed.

Older vehicles usually have a mechanical brake force distributor, which is mounted on the rear axle and reduced with a lever when lifting of the rear end via a valve to the brake pressure of the rear wheels. The electronic brake force distribution replaces these relatively inaccurate mechanical solution by an electronic system, especially since in the presence of ABS already the required sensors and actuators are available.

Technology and Operation

Normal function

Unlike the anti -lock braking system (ABS ), EBD but does not prevent the wheels from locking, but distributes the brake pressure only between the front and rear axle and to stabilize the vehicle, for example, when braking in a curve. EBD support the anti -lock braking system (ABS ), since this reduces the brake pressure only when the corresponding wheel is already blocked.

In contrast to the ABS when the brake light switch only one " supporting - informative ", but not a safety-relevant signal represents (ABS valve controls is calculated from the wheel speeds and would, even without a brake light switch signal function ), an EBD engaged only by a valid stop lamp switch signal in connection with the amount of the calculated slip at the rear initiated.

Fault and error detection

A good method to over-braking the rear axle to avoid with a failed brake light switch and to identify the error condition anyway, so is the use of redundant ( dual ) switches. Other solutions are focused on a simple (ie non-redundant ) cheaper switches and enhanced software, the lack of the switch signal - more or less - try to detect by Plausiblitätschecks.

History

Electronic brake force distribution was first introduced in 1994 by Opel and Bosch in the car Opel Omega Series 'B'. Driving for the development of the system was created by the elimination of the mechanical brake force distributor weight and cost advantage. Since the electronic brake force distribution within an ABS or ASR system was merely part of an extended to a few hundred bytes of software, they therefore did not require any new additional hardware.

The Bosch originally intended product name DME ( pressure reducing valve replacement logic) sounded too complicated and therefore never could prevail.