The ABS is help to make the stooping distance less and help to steer while breaking it increase the traction of the wheel and doesn't lock while hard breaking. The basic design of a braking system has been around and in use in other applications for many years. The brakes in a car use the simple principle of hydraulics. This principle reduces the amount of work required by the user. The above is tell about the abs.
The problem with the traditional braking system is that the force exerted by the brakes on the wheel cannot exceed the force of friction between the wheel and the road. If the braking force exceeds the force of friction from the road the vehicle will begin to slide. This problem brought about the invention of the anti-locking breaking system (ABS). The ABS detects drastic changes in the speed of the wheels. When a sharp
deceleration is detected the ABS will reduce the hydraulic pressure supplied to the braking system until the wheel begins to accelerate again. When the acceleration is detected the pressure is again increased until an unusual amount of deceleration is detected. The process is repeated until the user removes their foot from the brake pedal or the vehicle comes to a complete stop.
component :
1. Speed Sensor: The speed sensor is used to determine the acceleration or deceleration of the wheel. As shown in fig.
These sensors use a magnet and a coil of wire to generate a signal. The rotation of the wheel or differential induces a magnetic field around the sensor. The fluctuations of this magnetic field generate a voltage into the
sensor. A schematic of this system is shown in Figure 4.The ABS controller interprets this signal.Since the voltage inducted on the sensor is a result of the rotating wheel, this sensor can become inaccurate at slow speeds. The slower rotation of the wheel can cause inaccurate fluctuations in the magnetic field and thus cause inaccurate readings to the controller.
2. Valves: The valves within an ABS serve three distinct functions. The first function of the valves is to open and allow the hydraulic fluid from the brake pedal or the pump to reach the braking system. The second function of the valves is to maintain the current pressure provided to the braking system. This is accomplished by closing the valve to resist further pressure from the brake pedal. The third function of these valves is to reduce the amount of hydraulic pressure at the braking system. This is accomplished by opening the valves to allow the hydraulic fluid to be released from the braking system. A picture of a standard ABS valve and pumping system is show in Figure 5. The majority of problems with the valve system occur due to clogged valves. When a valve is clogged it is unable to open, close, or change position. An inoperable valve will prevent the system from modulating the valves and controlling pressure supplied to the brakes.
3. Pump: It is used to restore the pressure to the HYDRAULIC BRAKES after the valves is open.A signal from the controller will release the valve at the detection of wheel slip. After a valve release the
pressure supplied from the user, the pump is used to restore a desired amount of pressure to the braking system. The controller will modulate the pumps status in order to provide the desire amount of pressure and reduce slipping.Similar to the valves, the major limitation or mode of failure is due to blockage within the pump. A blockage within the pump will prevent the pump from supplying the correct pressure to the pumping system.
4: controller: The entire system is observed and manipulated by the ABS controller. The ABS ECU contains thousands of parameters which can be tuned for the car – although most ABS systems are supplied by companies such as Bosch, it's the software tuning which makes individual systems different for different cars. Vehicle manufacturers must strike a compromise between stability and the braking distance they hope to achieve, and must also set parameters for braking on different surfaces and scenarios. Even if two different cars have identical ABS hardware – it will have been tuned very differently for a sports car compared with an SUV.
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