Electronic brakeforce distribution
Encyclopedia
Electronic brakeforce distribution (EBD or EBFD), Electronic brakeforce limitation (EBL) is an automobile
brake
technology that automatically varies the amount of force
applied to each of a vehicle's brakes, based on road conditions, speed, loading, etc. Always coupled with anti-lock braking system
s, EBD can apply more or less braking pressure to each wheel in order to maximize stopping power whilst maintaining vehicular control. Typically, the front end carries the most weight and EBD distributes less braking pressure to the rear brakes so the rear brakes do not lock up and cause a skid. In some systems, EBD distributes more braking pressure at the rear brakes during initial brake application before the effects of weight transfer become apparent.
(ABS) monitors wheel speeds and releases pressure on individual wheel brake lines, rapidly pulsing individual brakes to prevent lock-up. During heavy braking, preventing wheel lock-up helps the driver maintain steering control. Modern ABS has an individual brake line for each of the four wheels, enabling different braking pressure on different road surfaces. For example, less braking pressure is needed to lock a wheel on ice than a wheel which is on bare asphalt. If the left wheels are on asphalt and the right wheels are on ice, during an emergency stop, ABS detects the right wheels about to lock and reduces braking force on the right wheels, helping to avoid lock-up and loss of vehicle control.
"The job of the EBD as a subsystem of the ABS system is to control the effective adhesion utilization by the rear wheels. The pressure of the rear wheels is approximated to the ideal brake force distribution in a partial braking operation. To do so, the conventional brake design is modified in the direction of rear axle overbraking, and the components of the ABS are used. EBD reduces the strain on the hydraulic brake force proportioning valve in the vehicle. EBD optimizes the brake design with regard to: adhesion utilization; driving stability; wear; temperature stress; and pedal force."
EBD may work in conjunction with ABS and Electronic Stability Control
("ESC") to minimize yaw accelerations during turns. ESC compares the steering wheel angle to vehicle turning rate using a yaw rate sensor. "Yaw" is the vehicle's rotation around its vertical center of gravity (turning left or right). If the yaw sensor detects more/less yaw than the steering wheel angle should create, the car is understeering or oversteering and ESC activates one of the front or rear brakes to rotate the car back onto its intended course. For example, if a car is making a left turn and begins to understeer (the car plows forward to the outside of the turn) ESC activates the left rear brake, which will help turn the car left. The sensors are so sensitive, and the actuation is so quick that the system may correct direction before the driver reacts. ABS helps prevent wheel lock-up and EBD helps apply appropriate brake force to make ESC work effectively.
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
brake
Brake
A brake is a mechanical device which inhibits motion. Its opposite component is a clutch. The rest of this article is dedicated to various types of vehicular brakes....
technology that automatically varies the amount of force
Force
In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...
applied to each of a vehicle's brakes, based on road conditions, speed, loading, etc. Always coupled with anti-lock braking system
Anti-lock braking system
An anti-lock braking system is a safety system that allows the wheels on a motor vehicle to continue interacting tractively with the road surface as directed by driver steering inputs while braking, preventing the wheels from locking up and therefore avoiding skidding.An ABS generally offers...
s, EBD can apply more or less braking pressure to each wheel in order to maximize stopping power whilst maintaining vehicular control. Typically, the front end carries the most weight and EBD distributes less braking pressure to the rear brakes so the rear brakes do not lock up and cause a skid. In some systems, EBD distributes more braking pressure at the rear brakes during initial brake application before the effects of weight transfer become apparent.
How ABS works
Under heavy braking, vehicle wheels may lock-up. The anti-lock braking systemAnti-lock braking system
An anti-lock braking system is a safety system that allows the wheels on a motor vehicle to continue interacting tractively with the road surface as directed by driver steering inputs while braking, preventing the wheels from locking up and therefore avoiding skidding.An ABS generally offers...
(ABS) monitors wheel speeds and releases pressure on individual wheel brake lines, rapidly pulsing individual brakes to prevent lock-up. During heavy braking, preventing wheel lock-up helps the driver maintain steering control. Modern ABS has an individual brake line for each of the four wheels, enabling different braking pressure on different road surfaces. For example, less braking pressure is needed to lock a wheel on ice than a wheel which is on bare asphalt. If the left wheels are on asphalt and the right wheels are on ice, during an emergency stop, ABS detects the right wheels about to lock and reduces braking force on the right wheels, helping to avoid lock-up and loss of vehicle control.
See also
- Brake AssistBrake assistBrake Assist is a generic term for an automobile braking technology that increases braking pressure in an emergency situation. The first application was developed jointly by Daimler-Benz and TRW/LucasVarity...
- Cornering Brake ControlCornering Brake ControlCornering Brake Control or CBC is an automotive safety system developed by BMW. It is a further development and expansion of the anti-lock braking system, designed to distribute braking force during braking whilst cornering.-See also:...
- Electronic stability controlElectronic stability controlElectronic stability control is a computerized technology that may potentially improve the safety of a vehicle's stability by detecting and minimizing skids. When ESC detects loss of steering control, it automatically applies the brakes to help "steer" the vehicle where the driver intends to go...
- Automobile safetyAutomobile safetyAutomobile safety is the study and practice of vehicle design, construction, and equipment to minimize the occurrence and consequences of automobile accidents. Automobile safety is the study and practice of vehicle design, construction, and equipment to minimize the occurrence and consequences of...
How EBD works
As per SAE technical paper #920646 - Buschmann et al."The job of the EBD as a subsystem of the ABS system is to control the effective adhesion utilization by the rear wheels. The pressure of the rear wheels is approximated to the ideal brake force distribution in a partial braking operation. To do so, the conventional brake design is modified in the direction of rear axle overbraking, and the components of the ABS are used. EBD reduces the strain on the hydraulic brake force proportioning valve in the vehicle. EBD optimizes the brake design with regard to: adhesion utilization; driving stability; wear; temperature stress; and pedal force."
EBD may work in conjunction with ABS and Electronic Stability Control
Electronic Stability Control
Electronic stability control is a computerized technology that may potentially improve the safety of a vehicle's stability by detecting and minimizing skids. When ESC detects loss of steering control, it automatically applies the brakes to help "steer" the vehicle where the driver intends to go...
("ESC") to minimize yaw accelerations during turns. ESC compares the steering wheel angle to vehicle turning rate using a yaw rate sensor. "Yaw" is the vehicle's rotation around its vertical center of gravity (turning left or right). If the yaw sensor detects more/less yaw than the steering wheel angle should create, the car is understeering or oversteering and ESC activates one of the front or rear brakes to rotate the car back onto its intended course. For example, if a car is making a left turn and begins to understeer (the car plows forward to the outside of the turn) ESC activates the left rear brake, which will help turn the car left. The sensors are so sensitive, and the actuation is so quick that the system may correct direction before the driver reacts. ABS helps prevent wheel lock-up and EBD helps apply appropriate brake force to make ESC work effectively.