Honda-The Power of Dreams
Honda Announces the Development of a New Braking System

Tokyo, September 19, 1997 --- Honda announced today the development of a new type of braking system with Electronic Brake force Distribution (EBD). This system will be made available for the first time on a domestic model in a coming new model slated for later this autumn.

Long an advocate of active safety, Honda was one of the first to promote ABS. The new EBD system we are introducing today adds a new control logic to the existing ABS system, electronically controlling front/rear brake pressure distribution according to front/rear weight distribution. This system improves braking stability and performance, particularly under heavy load. It is particularly effective in recreational vehicles, minivans and other vehicles showing large front/rear weight distribution changes depending on load.

For optimum brake performance, brake pressure distribution between front and rear wheels should take into consideration both load condition and weight transfer under braking.

In the past, variable brake pressure distribution systems relied on suspension movement to control brake pressure distribution. However these mechanical systems were quite complex. Brake pressure distribution in passenger cars was thus controlled by a proportioning valve that maintained a fixed front/rear brake pressure distribution under all circumstances.

The system uses the difference in front/rear wheel rotational speed to calculate the maximum brake amount that the rear wheels can safely bear. EBD then acts upon the ABS actuator to automatically adjust brake pressure to fully utilize the increased rear brake limit when heavily loaded.

Technical Overview

  • Theoretical background
When a car is heavily loaded, most of the increase in weight is born by the rear wheels. With traditional brake systems using proportioning valves, front/rear distribution remains fixed, making it very difficult to fully utilize rear wheel braking capability.
EBD varies front/rear brake pressure distribution according to load, thus improving overall braking performance.

Image of EBD in action

Image of EBD in action

  • Increase in braking performance through optimized fore-aft brake balance

    Overall brake performance is increased by optimizing front/rear brake pressure distribution according to vehicle load.

    Image of EBD in action

  • Description of the system.

    The sensors and actuators are shared with the ABS system. EBD basically adds a new control logic into the ABS ECU.

Description of the system