modern brake system

7/30/2019 modern brake system

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Function of Electronic Brake Force

Distribution System (EBD)

Is a technology that enables the braking force of avehicle to be increased or applied automatically, dependingon road conditions, speed of the vehicle, and weight ofvehicle.

In a regular braking system, when the brake pedal isapplied, the brake fluid travels from the master cylinder tothe brake cylinders. When the fluid goes inside the brakecylinder, the pressure of the fluid being applied forces thetwo pistons to push out resulting in the brake shoes or padsbeing pushed out. This push or pressure is in directproportion to the push by the pistons, which causes theshoes or pads to rub against the drum or caliper. Thisreaction creates friction and decreases the turning of thewheels.


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What EBD does is it electronically monitors, through sensors, theconditions of the road, the feel of pressure on the brake pedal, and vehicleweight, to determine when to apply pressure to the wheel cylinders. Thesensors are designed to monitor the movements of the wheels anddetermine based on weight, which wheels may need the maximum forceapplied, as per the condition met. Supposedly, this is to provide better and

more precise braking under every condition imaginable. Since the frontend has the most weight on a vehicle, the EBD system recognizes this andelectronically controls the back brakes so when the driver applies thebrakes, the back brakes do not lock up causing a skid.

EBD is a good system for drivers because it can increase the vehicles

ability to stop under any conditions. But this is only effective if the brainsof the computer works, along with the sensors that make up the system. Ifone of those sensors should fail, and you run into a bad situation, youcould end up in a precarious predicament.


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Operation of Electronic Brake Force

Distribution (EBD)

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 over braking, 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 under steering or over steering and ESC activates one of

the front or rear brakes to rotate the car back onto its intended course. For example, if a caris making a left turn and begins to under steer (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.
http://en.wikipedia.org/wiki/Electronic_Stability_Controlhttp://en.wikipedia.org/wiki/Electronic_Stability_Control


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Function of Brake Assist Principle (BA)

Emergency brake assist (EBA) or Brake Assist (BA or BAS) is ageneric term for an automobile braking technology that increasesbraking pressure in an emergency situation. The first applicationwas developed jointly by Daimler-Benz and TRW/LucasVarity.Research conducted in 1992 at the Mercedes-Benz driving

simulator in Berlin revealed that more than 90% of drivers fail tobrake with enough force in emergency situations.

By interpreting the speed and force with whichthe brake pedal is pushed, the system detects if the driver is tryingto execute an emergency stop, and if the brake pedal is not fullyapplied, the system overrides and fully applies the brakes until

the Anti-lock Braking System (ABS) takes over to stop the wheelslocking up. The BA function is triggered through extension of theESC software and requires inputs e.g. from the pressure sensor inthe tandem master cylinder.
http://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Automobilehttp://en.wikipedia.org/wiki/Daimler-Benzhttp://en.wikipedia.org/wiki/Daimler-Benzhttp://en.wikipedia.org/wiki/Brakehttp://en.wikipedia.org/wiki/Forcehttp://en.wikipedia.org/wiki/Brakehttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Brakehttp://en.wikipedia.org/wiki/Forcehttp://en.wikipedia.org/wiki/Daimler-Benzhttp://en.wikipedia.org/wiki/Daimler-Benzhttp://en.wikipedia.org/wiki/Daimler-Benzhttp://en.wikipedia.org/wiki/Automobile


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Construction of Brake Assist Principle (BA) This system supports pedal actuation during emergency braking by

providing additional braking force. Once brake force exceeds a certain

level, the brake booster gain is increased, and, while the braking force isapplied, the effectiveness of ABS becomes evident.

Brake Assist is standard equipment on the Colt, Lancer, Air trek, Dion, and

Grand is, and an optional set with ABS on mini-sized vehicles


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Operation of the Brake Assist Principle

(BA) Brake Assist detects circumstances in which emergency braking is required

by measuring the speed with which the brake pedal is depressed. Somesystems additionally take into account the rapidity of which theaccelerator pedal is released, pre-tensioning the brakes when a "panicrelease" of the accelerator pedal is noted. When panic braking is detected,the Brake Assist system automatically develops maximum brake boost in

order to mitigate a driver tendency to brake without enough force. Indoing so, Brake Assist has been shown to reduce stopping distance by asignificant margin; up to 20% in some studies.

The brake power assist device increases the braking force by augmentingthe force applied when stepping on the brakes when emergency brakingor powerful braking is necessary. The device thus enables even those who

may be unable to step on the brake forcefully to exert the same degree ofbraking power as stronger individuals during emergency braking. The BASPlus system has been shown to significantly reduce the incidenceof collisions, and so is very significant in the development of driver aidsthat improve road safety.


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Function of Electronic Stability Control

(ESC)

Electronic stability control (ESC) is a safety featurethat detects and prevents (or recovers from)skids. ESC can help keep the driver from losingcontrol of the car in a panic swerve or when

driving on slippery roads. Braking is automaticallyapplied to wheels individually, such as the outerfront wheel to counterover steeror the innerrear wheel to counter under steer. Some ESC

systems also reduce engine power until control isregained. ESC does not improve a vehicle'scornering performance instead it helps tominimize the loss of control.
http://en.wikipedia.org/wiki/Oversteerhttp://en.wikipedia.org/wiki/Understeerhttp://en.wikipedia.org/wiki/Understeerhttp://en.wikipedia.org/wiki/Understeerhttp://en.wikipedia.org/wiki/Understeerhttp://en.wikipedia.org/wiki/Understeerhttp://en.wikipedia.org/wiki/Oversteer


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Construction of Electronic Stability

Control (ESC) ESC uses sensors in the car (wheel speed sensors, steering

wheel position sensors, yaw sensors, etc.) to determinewhich direction the driver wants the car to go, andcompares that to which way the car is actually going. If thesystem senses that a skid is imminent or has already started

-- in other words, that the car is not going in the directionthe driver is telling it to go. It can apply the brakes onindividual wheels to bring the car back under control.Because the system can brake individual wheels, whereasthe driver can only brake all four wheels at once.

The sensors used for ESC have to send data at all times inorder to detect possible defects as soon as possible. Theyhave to be resistant to possible forms of interference (rain,holes in the road, etc.).


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The most important sensors are:

Steering wheel angle sensor: determines the driver's intended rotation;

i.e. where the driver wants to steer. This kind of sensor is often based

on AMR elements.

Yaw rate sensor : measures the rotation rate of the car e.g. how much the

car is actually turning. The data from the yaw sensor is compared with the

data from the steering wheel angle sensor to determine regulating action.

Lateral acceleration sensor: often an accelerometer.

Wheel speed sensor : measures the wheel speed.


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Operation of Electronic Stability

Control (ESC) ESC works in the background and continuously monitors steering and vehicle

direction. It compares the driver's intended direction (determined through the

measured steering wheel angle) to the vehicle's actual direction (determined

through measured lateral acceleration, vehicle rotation (yaw), and individual road

wheel speeds).

ESC intervenes only when it detects a probable loss of steering control, e.g when

the vehicle is not going where the driver is steering. This may happen, for example,

when skidding during emergency evasive swerves, under steer or over steer during

poorly judged turns on slippery roads, or hydroplaning. ESC may also intervene in

an unwanted way during high-performance driving, because steering input may not

always be directly indicative of the intended direction of travel .ESC estimates thedirection of the skid, and then applies the brakes to individual wheels

asymmetrically in order to create torque about the vehicle's vertical axis, opposing

the skid and bringing the vehicle back in line with the driver's commanded

direction. Additionally, the system may reduce engine power or operate the

transmission to slow the vehicle down.
http://en.wikipedia.org/wiki/Accelerationhttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Understeerhttp://en.wikipedia.org/wiki/Oversteerhttp://en.wikipedia.org/wiki/Hydroplaning_(tires)http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Hydroplaning_(tires)http://en.wikipedia.org/wiki/Oversteerhttp://en.wikipedia.org/wiki/Understeerhttp://en.wikipedia.org/wiki/Yaw_anglehttp://en.wikipedia.org/wiki/Acceleration


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ESC can work on any surface, from dry pavement to frozen

lakes. It reacts to and corrects skidding much faster and more

effectively than the typical human driver, often before the

driver is even aware of any imminent loss of control. In fact,this led to some concern that ESC could allow drivers to

become overconfident in their vehicle's handling and/or their

own driving skills. For this reason, ESC systems typically inform

the driver when they intervene, so that the driver knows thatthe vehicle's handling limits have been approached.


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Function of Traction Control System

(TRAC) A traction control system (TCS), also known as anti-slip regulation (ASR), is

typically (but not necessarily) a secondary function of the anti-lock braking

system (ABS) on production motor vehicles, designed to prevent loss

oftraction of driven road wheels. When invoked it therefore enhances driver

control as throttle input applied is mis-matched to road surface conditions

(due to varying factors) being unable to manage applied torque.

The purpose of the traction control system is to prevent wheel spin from

occuring due to acceleration. The maximum torque that can be transmitted

to the wheel is determined by the coefficient of friction generated between

the road and the tires. If torque exceeds that level, the wheels are likely tospin. Conditions for TRAC operation may include loose gravel, slippers road

surfaces, acceleration while cornering and hard acceleration.

Once active, the TRAC system reduces engine torque and drive wheel speed

as necessary to bring the vehicle under control which improves vehicle

stability when starting, acceleration or turning on slippery roads.
http://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Motor_vehiclehttp://en.wikipedia.org/wiki/Traction_(engineering)http://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Traction_(engineering)http://en.wikipedia.org/wiki/Motor_vehiclehttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_system


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Construction of Traction Control

System (TRAC) Traction control shares many of the same components and

sensor inputs with the ABS system:

A common control module is often used with additionalsoftware and control circuits for TCS. In some vehicles, aseparate TCS control module may be used.

The same wheel speed sensors are used to monitor wheelspeeds.

The same pump and high pressure accumulator are used togenerate and store hydraulic pressure for TCS braking.

The same modulator (with a couple of extra solenoidvalves) is used to control braking.


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Operation of Traction Control System

(TRAC) When the traction control computer (often incorporated

into another control unit, like the anti-lock brakingsystem module) detects one or more driven wheelsspinning significantly faster than another, it invokes theABS electronic control unit to apply brake friction to wheels

spinning with lessened traction. Braking action on slippingwheel(s) will cause power transfer to wheel axle(s) withtraction due to the mechanical action withina differential. All-wheel drive AWD vehicles often have anelectronically controlled coupling system in the transfer

case or transaxle engaged (active part-time AWD), orlocked-up tighter (in a true full-time set up driving allwheels with some power all the time) to supply non-slipping wheels with (more) torque.
http://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Electronic_control_unithttp://en.wikipedia.org/wiki/Electronic_control_unithttp://en.wikipedia.org/wiki/Differential_(mechanical_device)http://en.wikipedia.org/wiki/All-wheel_drivehttp://en.wikipedia.org/wiki/Differential_(mechanical_device)http://en.wikipedia.org/wiki/All-wheel_drivehttp://en.wikipedia.org/wiki/Transfer_casehttp://en.wikipedia.org/wiki/Transfer_casehttp://en.wikipedia.org/wiki/Transaxlehttp://en.wikipedia.org/wiki/Transfer_casehttp://en.wikipedia.org/wiki/Transfer_casehttp://en.wikipedia.org/wiki/Transaxlehttp://en.wikipedia.org/wiki/Transaxlehttp://en.wikipedia.org/wiki/Transfer_casehttp://en.wikipedia.org/wiki/Transfer_casehttp://en.wikipedia.org/wiki/All-wheel_drivehttp://en.wikipedia.org/wiki/All-wheel_drivehttp://en.wikipedia.org/wiki/All-wheel_drivehttp://en.wikipedia.org/wiki/Differential_(mechanical_device)http://en.wikipedia.org/wiki/Electronic_control_unithttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_systemhttp://en.wikipedia.org/wiki/Anti-lock_braking_system


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The advantages of using Electronic Brake Force Distribution System (EBD)

Function improvement of the base-brake system.

Compensation for the different friction coefficients.

Elimination of the proportioning valve.

Failure recognition by the warning lamp.

Adjusts automatically to a variety of conditions to ensure the brakes areused as efficiently as possible. It reduces the risk of brakes locking andprevents tire skids.

Utilization of driving stability, wear, temperature stress and pedal force.

The sensors are so sensitive, and the actuation is so quick that the systemmay correct direction before the driver reacts.

ABS helps prevent wheel lock-up and EBD helps apply appropriate brakeforce to make ESC work effectively.

The disadvantages of using Electronic Brake Force Distribution System(EBD)

If one of the sensor problems or fail to work in good condition, it can causedamage for the driver because this EBD controlled by the computer system.


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The advantages of using Brake Assist Principle (BA)

When the braking force is lacking during an emergencysituation, braking pressure is increased to generate greater

braking force. This raises the possibility of risk avoidance. Detects emergency stop and increased braking pressure is

applied.

Builds up pressure until both axels are regulated by ABS.

Braking power is exploited to the fullest. Minimizes the vehicles braking distance, saving lives.

The disadvantages of using Brake Assist Principle (BA)

Active Brake Assist does not take any responsibility away fromthe driver.

Active Brake Assist takes effect from a minimum speed of 15km/h.

Active Brake Assist does not react to stationary obstacles.


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The advantages of using Electronic Stability Control (ESC)

Bends or on slippery roads.

Optimum use of road surface friction together with TCS.

The disadvantages of using Electronic Stability Control(ESC)

People used to driving vehicles equipped with ESC might

over estimate their driving skills when placed in a vehiclewithout ESC, thus increasing the risk of skidding.

What ESC cannot do

Improve tire traction characteristics (-slip curve).

Increase vehicle lateral acceleration capacity.

Change any of the Laws of Physics.


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The disadvantages of using Traction Control System (TRAC)

Cost of purchase. The high-functioning gear that's involvedin traction control can make a car an increasingly expensive

purchase. Those looking to save money on a vehicle may belooking for older models that were cheaper to make.

Cost of maintenance. A vast range of things can damagetraction control or anti-lock brake sensors, and with each ofthese carrying a hefty price tag, the cost of repairs can

easily spin out of control. Those with past experiencepaying for a damaged anti-lock brake system may have a bigaversion to getting even more in additional safety featuresloaded into a vehicle.

Limited use. Traction control systems are not ideal for all

kinds of situations. Many experts claim drivers are betteroff with four wheel drive options for off-road use. Off-roaduse can also cause damages to the traction control system.

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