AntiLock Braking System - Essay Example

Anti–Lock Braking System Name of the Student: Name of the Instructor: Name of the course: Code of the course: Submission date: Anti–Lock Braking System Introduction Anti- lock braking system, (ABS) is a braking system that is designed to ensure that drivers maintain maximum steering ability in addition to avoiding skidding while braking in varying scenarios (Antić., Nikolić, Mitić, Milojković & Perić, 2010, p.42). ABS was specifically designed to improve the braking ability of vehicles on wet surfaces. The chances of sliding, an occurrence that reduces the ability of the driver to steer a vehicle are higher on wet surfaces For this reason, ABS seeks to prevent the wheels from skidding and control the speeds of various wheels independently hence ultimately enhancing steering on wet surfaces. The following essay will discuss the braking theory, analyse the ABS elements, types of ABSs, how ABS functions, advantages and disadvantages of ABS and compare and contrast ABS with conventional braking system. Braking Theory It is important to give a short insight into the braking theory. A braking system is a mechanical system that is designed to reduce or halt the motion of an automobile. Braking systems achieve this by converting kinetic energy to heat, electrical or potential energy by the use of various approaches. The efficiency of a braking system is determined by four factors namely pressure, frictional contact surface, coefficient of friction and heat dissipation. Under this point, it is important to note that the coefficient of friction between the tires and the road surface also determines the efficiency of the braking operation in that where the coefficient is small, sliding is due to occur when excessive pressure is exerted on the brake pad. Sliding has an effect of reducing the ability of the driver to steer the car and also tends to increase the total distance required to bring an automobile to a halt. For this reason, ABS systems were developed so as to eliminate sliding (Nice 2014, p.1). Owing to the fact that braking is an important process in the operation of an automobile, it is important that its efficiency be set to the maximum levels possible. Sometimes, fractions of seconds in braking are thin margin between life and death. Anti-Lock Braking System’s Elements A typical ABS has four main components namely speed sensors, pump, controller and valves. Speed sensors are meant to sense the speed at which each vehicle is rotating at. It is worth noting that for effective steering of the automobile to be possible, all the wheels must be moving at the same speed. This means that the vehicle does not deviate from its course. Speed sensors are supposed to ensure that there is this uniform motion and control the braking pressure when the wheels are just about to lock up. This solves the locking problem. The valve is designed to control the flow of the braking / hydraulic fluid to the braking system (Nice 2014, p.1). Each brake is fitted with an individual valve. Typically, the valve has three main positions in ABSs. In the first position, the valve is open and the pressure developed in the master cylinder is allowed to the brake. In the second potion, the valve closes, blocking the pressure transmission line. This is meant to prevent more exertion of pressure on the brake pad when the driver presses the brake pedal. In the third position, the valve opens and releases some pressure from the pad. The function of the pump is to provide pressure to the braking fluid; hence leading to its effective transmission to the braking pad. Lastly, the controller’s function is to automatically oversee the accurate execution of processes in the braking system (Nice 2014, p.1). The controller is a computer system that coordinates input from the speed sensors and the commands to the valves. The following figure illustrates an ABS system: Anti-Lock Brake Components (Nice 2014, p.1) Types of ABS There are three main types of ABS that are names according to the number of channels involved. The first type of ABS is four channel, four sensor ABS. It is the best ABS channel. In this system, each wheel has a speed sensor and an individual valve. This means that each wheel is controlled individually. This makes the four channel four sensor system the most efficient braking system in the ABS class. The controller harmonises the control of the four wheels (Nice 2014, p.1). The second type of ABS is the three channel three sensor ABS. This braking system has three sensors and three valves. Each of the front wheels has a sensor and valve. However, the two rear wheels share a sensor and a valve. The speed sensor is normally located at the rear wheel axle. This type of braking system is normally found in pickups. The efficiency of this braking system is lower than that for the four channel, four sensor ABS due to the fact that the two rear wheels are operated using a single system and both of them have to lock up before the system is activated (Nice 2014, p.1). This means that the vehicle may be in motion whilst one of the rear wheels is locked up, hence reducing the braking efficiency. The third ABS system is the one channel, one sensor ABS that has a single valve and sensor for the rear wheels. This braking system is common for rear wheel drive vehicles especially pickups. Just as is the case with three channel three sensor ABS, the rear wheels are monitored together and ABS sets in when both wheels lock in. How ABS Functions The braking cycle starts when the brakes are applied by the driver on the brake pedal. On pressing the brakes, the brake fluid is forced from the master cylinder and flows to the hydraulic control unit inlet ports via the outlet ports of the cylinder. The fluid normally passes on to the hydraulic control unit ports through solenoid valves to the individual hydraulic control units for individual wheels (Nice 2014, p.1). In an ideal four wheel, four sensors ABS, the fluid is forced on to the braking system of the individual wheels. The pressure of application of the fluid on the individual a braking systems determines the rate of deceleration of the wheels. In instances where the exerted pressure is excessive, the specific wheel on which it is exerted on undergoes through a rapid deceleration cycle as compared to other wheels. This behaviour is sensed by the speed sensors that in turn transmit the information to the controller. Such a rapid deceleration is as a result of an unwanted phenomenon. The controller opens the valve, releasing some of the pressure on the affected wheel until some acceleration is noted. The speed sensor then monitors the wheel and identifies any other unwanted behaviour. Any unwanted behaviour is met by the application or release of pressure on the brake pad, hence leading to efficient braking (Antić., Nikolić, Mitić, Milojković & Perić, 2010, p.43). This sequence is replicated on all wheels. However, the algorithm for the control of wheels that share valves and sensors is different since ABS engages when both wheels lock in. Pros and Cons of ABS systems The main advantage of ABS is that it increases the braking efficiency. ABS is associated with a higher braking efficiency. Since wheel locking in is eliminated by the brake fluid pressure regulation of the braking system, an accurate time and distance of braking can be identified (Nice 2014, p.1). Secondly, ABS enables drivers to steer vehicles more efficiently during braking. This is specifically important when the vehicle is moving on wet surfaces that are associated with a lower coefficient of friction (Antić., Nikolić, Mitić, Milojković & Perić, 2010, p.42). With ABS, drivers are able to avoid accidents and also be more precise during braking. The main disadvantage of ABS is that it adds on to the cost of vehicle manufacture. Ideally, vehicles that are fitted with ABS are more expensive as a compared those that are not. Additionally ABS systems can fail, just like other mechanical and electrical systems in an automobile. ABS Versus Conventional Systems The braking efficiency of ABS system is higher as compare to that of conventional systems. This justifies the higher cost associated with ABS systems. However, there has been a criticism about the speed within which braking occurs using ABS as compared to other conventional mechanisms. Studies have shown that ABS is slower as compared to other systems. However, speed of braking cannot be used to justify the criticism against ABS unless in special scenarios such as racing. Conclusion In conclusion, it has been identified from this essay that anti-lock braking systems are focussed on eliminating sliding during braking. This leads to enhanced braking efficiency and better steering of the vehicles. An ABS system is made up of four basic components namely speed sensors, pump, valves and controller. There are three types of ABS namely four valves, four sensors, three sensor, three valves, three sensors and one valve, one sensor systems. ABS works on the principle of regulation of pressure on the brake pad just before locking in sets in. analysing the advantages of ABS and how it compares to conventional braking systems, it can be acknowledged that it is a far much better braking system whose use should be adopted in automobiles. References Antić., D., Nikolić, V., Mitić, D., Milojković, M., Perić, S., (2010). Sliding Mode Control Of Anti-Lock Braking System: An Overview, Automatic Control and Robotics Vol. 9, No 1, pp. 41 - 58 Nice, K., (2014). How Anti-Lock Brakes Work, How Stuff Works, Retrieved on 15th July 2014 from http://auto.howstuffworks.com/auto-parts/brakes/brake-types/anti-lock-brake1.htm Read More