The Project work submitted to

Rajiv Gandhi Proudyogiki Vishwavidyalaya,

Bhopal

Towards partial fulfillment of

The Degree of

Bachelor of Engineering

In

Mechanical Engineering

Submitted to: - Submitted by:- Mr. Akhare Bhushan Neeraj ku. shukla(0818me091062) Jitendra singh hada(0818me091044) Nitesh rathor(0818me091064) Jitendra singh (0818me091046)

Mechanical Engineering Department

INDORE INSTITUTE OF SCIENCE AND TECHNOLOGYINDORE (M.P.)

2011-2012

2011-2012

RECOMMENDATION

The project report entitled ,”Value Analysis of Anti Lock Braking System”,submitted to the Rajiv Ghandhi Proudyogiki Viswavidhyalaya,Bhopal, M.P by Mr. Neeraj kumar shukla ,Mr. Jitendra singh hada,Mr.nitesh rather and Mr.Jitendra singh during the academic year 2012, As a partial fulfilment for the award of degree of he bachelor of engineering in Mechanical Engineering, is a record of their own work carried out by the team under our direct supervision, in the department of M.E., IIST INDORE. The work contained in the report is a satisfactory account of their project work and is recommended for the award of the degree.

Guide Head

Mr. Bhusan Akhare Mr. Rajeev vijaywargiya

(Asst. proff. M.E. Dept.) (HOD, ME Dept.)

INDORE INSTITUTE OF SCIENCE AND TECHNOLOGY

2011-2012

CERTIFICATE

This is to certify that the project work entitled “VALUE ANALYSIS OF ANTI LOCK BRAKING

SYSTEM” submitted by........................., student of Third year B.E. (Mechanical Engineering)

in the year 2012-2013 of Computer Engineering Department of this institute, is a satisfactory

account of his work based on syllabus which is approved for the award of degree of Bachelor

of Engineering in Mechanical Engineering.

Internal Examiner External Examiner

Date: Date:

ACKNOWLEDGEMENT

After the completion of this Project work, words are not enough to express my feelings about all those who helped me to reach my goal; feeling above this is my indebtedness to The Almighty for providing me this moment in life.In this project we received constant support from our esteemed HOD Mr. ...........I am heartily indebted to Mr..................... for his constant support and guidance. Without his guidance and scholarly suggestion an urge to bring out the best would not have been possible. I hope to propagate his scientific, industrial and professional fervors to the best of my abilities. His clear view and knowledge provided help during every phase of Project Development. His perpetual motivation, patience and excellent expertise in discussion during progress of the project work have benefited me to an extent, which is beyond expression. His depth and breadth of knowledge of Computer Engineering field made me realize that theoretical knowledge always helps to develop efficient operational software, which is a blend of all core subjects of the field. He was major support to me throughout my project, being available with his odd ideas, inspiration and encouragement. It is a through his masterful guidance that I have been able to complete my Project.

I am also thankful to all the Teaching and Non-Teaching staff and Lab Assistants from Computer Engineering Department and the Friends and people who helped me directly or indirectly for the completion of this project, with success.

The successful completion of a Project is generally not an individual effort. It is an outcome of the cumulative effort of a number of persons, each having their own importance to the objective. This section is a vote of thanks and gratitude towards all those persons who have directly or indirectly contributed in their own special way towards the completion of this project.

Last but not the least, I would like to express my deep appreciation for my family members for providing their kind support and encouragement without which the completion of this project would be a dream.

Thanks to GOD for the unwavering support.

ABSTRACT

Design and Fabrication of Anti-Lock Braking System “An anti-lock brake system is a feedback control system that modulates brake pressure in response to measured wheel deceleration, preventing the controlled wheels from becoming fully locked.”

Anti-Lock Braking Systems (ABS) are designed to maintain driver control and stability of the car during emergency braking. Locked wheels will slow a car down but will not provide steering ability. ABS allows maximum braking to be applied while retaining the ability to'steer out of trouble‘. The operation of ABS can slightly reduce stopping distance in some cases like on wet road surfaces, but it can increase the stopping distance in others,as may be the case in deep snow or gravel. An ABS system monitors four wheel speed sensors to evaluate wheel slippage. Slip can be determined by calculating the ratio of wheel speed to vehicle speed, which is continuously calculated from the four individual wheel speeds. During a braking event, the function of the control system is to maintain maximum possible wheel grip on the road - without the wheel locking - by adjusting the hydraulic fluid pressure to each brake by way of electronically controlled solenoid valves. While ABS offers improved vehicle control in some circumstances, it can also present disadvantages including increased braking distance on slippery surfaces such as ice, packed snow, gravel, steel plates and bridges, or anything other than dry pavement. ABS has also been demonstrated to create a false sense of security in drivers, who may drive more aggressively as a result.Since initial widespread use in production cars, anti-lock braking systems have evolved considerably. Recent versions not only prevent wheel lock under braking, but also electronically control the front-to-rear brake bias. This function, depending on its specific capabilities and implementation, is known as electronic brakeforce distribution (EBD), traction control system, emergency brake assist, or electronic stability control.

INTRODUCTION

Antilock braking systems (ABSs) are electronic systems that monitor and control wheel slip during vehicle braking. ABSs can improve vehicle control during braking, and reduce stopping distances on slippery (split or low coefficient of friction) road surfaces by limiting wheel slip and minimizing lockup. Rolling wheels have much more traction than locked wheels. Reducing wheel slip improves vehicle stability and control during braking, since stability increases as wheel slip decreases.

ABSs can be applied to nearly all types of vehicles and can be successfully integrated into hydraulic and air brake systems.

Fig:-1-Anti lock braking system

WORKING PRINCIPLE OF ABS

An ABS consists of several key components: electronic control unit (ECU), wheel speed sensors, modulator valves, and exciter rings. Here’s how these components work together:-

1. Wheel speed sensors constantly monitor and send electrical pulses to the ECU at a rate proportional to the wheel speed.

2. When the pulse rates indicate impending wheel lockup, the ECU signals the modulator valve(s) to reduce and/or hold the brake application pressure to the wheel(s) in question.

3. The ECU then adjusts pressure, seeking one which gives maximum braking without risking wheel lockup.

4. When the ECU acts to modulate the brake pressure, it will also (on most vehicles) turn off the retarder (if so equipped) until the risk of lockup is over.

5. The ECU continually checks itself for proper operation. If it detects a malfunction/failure in the electrical/electronic system, it will shut down that part of the ABS affected by the problem—or the entire ABS—depending upon the system and the problem. When this happens, the ABS malfunction lamp lights. An ABS adjusts brake pressure much faster and more accurately than can drivers. It’s faster because:

• electronic controls are very fast and• ABS modulator valves are physically closer to the brakes than is the driver’s foot brake valve.

It is more effective, too, because an ABS can tailor the brake pressure to each wheel or set of wheels to provide maximum braking/stability. Some vehicles also use a traction control system in conjunction with the ABS. Traction control helps the ABS improve vehicle traction by minimizing wheel slip on the drive axle during acceleration. If a wheel on the drive axle starts to slip, the traction control system automatically brakes the wheel slightly, transferring engine torque to the wheels withbetter traction. If all the drive wheels start to slip, the traction control system may also reduce engine power.Traction control systems are referred to by several different names, depending on the manufacturer. These include:• Automatic Traction Control (ATC)• Traction Control (TC)

Fig:-2-BlockdiagramofAntilockbrakingsystem

Fig:-Electronic control unit

Fig:-Hydraulic moderator

COMPONENTS OF ABS

Electronic Control Unit (ECU)

Modulator Valves

Wheel Speed Sensors

pump

ELECTRONIC CONTROL UNIT :- The ECU processes all ABS information and signal functions. It receives and interprets voltage pulses generated by the sensor pickup as the exciter teeth pass by, and uses this information to determine:

• Impending wheel lock-up.

• when / how to activate the ABS modulator valves.

The ECU connects to the following ABS components: wheel speed sensors, ABS modulator valves, power source, ground, warning lamps.

MODULATOR VALVE :- ABS modulator valves regulate the air pressure to the brakes during ABS action. When not receiving commands from the ECU, the modulator valve allows air to flow freely and has no effect on the brake pressure. The ECU commands the modulator valve to either:

• change the air pressure to the brake chamber, or

• hold the existing pressure.

However, it cannot automatically apply the brakes, or Increase the brake application pressure above the level applied by the driver.

WHEEL SPEED SENSORS:- The anti-lock braking system needs some way of knowing when a wheel is about to lock up. The speed sensors, which are located at each wheel, or in some cases in the differential, provide this information.

Fig:-wheel speed sensor

PUMP :- Since the valve is able to release pressure from the brakes, there has to be some way to put that pressure back. That is what the pump does; when a valve reduces the pressure in a line, the pump is there to get the pressure back up.

Fig:- Working of pump

DIFFERENT TYPES OF ABS

One-channel, one-sensor ABS:-. It has one valve, which controls both rear wheels, and one speed sensor, located in the rear axle. This system operates the same as the rear end of a three-channel system. The rear wheels are monitored together and they both have to start to lock up before the ABS kicks in. In this system it is also possible that one of the rear wheels will lock, reducing brake effectiveness. This system is also easy to identify, as there are no individual speed sensors for any of the wheels.

Four-channel, four-sensor ABS :- There is a speed sensor on all four wheels and a separate valve for all four wheels. With this setup, the controller monitors each wheel individually to make sure it is achieving maximum braking force.

Three-channel, three-sensor ABS :- it has a speed sensor and a valve for each of the front wheels, with one valve and one sensor for both rear wheels. The speed sensor for the rear wheels is located in the rear axle. This system provides individual control of the front wheels, so they can both achieve maximum braking force. The rear wheels, however, are monitored together; they both have to start to lock up before the ABS will activate on the rear. With this system, it is possible that one of the rear wheels will lock during a stop, reducing brake effectiveness.

Three-channel, four-sensor ABS:-There is a speed sensor on all four wheels and a separate valve for each of the front wheels, but only one valve for both of the rear wheels.

VALUE ANALYSIS

WHAT IS VALUE ANALYSIS ?

Value analysis is a systematic effort to improve upon cost and/or performance of products (services), either purchased or produced. It examines the materials, processes, information systems, and the flow of materials involved. Value Analysis efforts began in earnest during WW II. GE, concerned with the difficulties in obtaining critical listed materails to produce war material, assigned an engineer, Lawrence D Miles to the Purchasing department. His mission was to find adequate material and component substitutes for critical listed material to manufacture needed war equipment. In his search, Miles found that each material has unique properties that could enhance the product if the design was modified to take advantage of those properties.

Miles discovered that he could meet or improve product performance and reduce its production cost by understanding and addressing the intended function of the product. His method was - Blast (dissecting products to discern key competitive advantages), Create (detailed analysis of the disassembled products, identifying those functions of concern and soliciting ideas for improving), Refine (selecting the most value adding, cost-effective ideas and preparing a business case for the implementation of the proposals) - the VA Tear Down Analysis. The key element in Miles' work is that he separated Function (what it must do) from the characteristics of the design (how it does it). Value = Function/Cost (esteem value - want, exchange value - worth, utility value - need).

US Navy adopted this in 1945 as Value Engineering. The Defense Department described Value Engineering as a "before the fact" activity applying the value methodology during the product design phase and Value Analysis as "after the fact" activity, practicing the value process following design release, during the production of the product.

Why is it important?

Implemented diligently, value analysis can result in: -

1. reduced material use and cost2. reduced distribution costs 3. reduced waste4. improved profit margins 5. increased customer satisfaction

6. increased employee morale.

When to use it?

Value analysis should be part of a continuous improvement effort.

How to use it?

Start by asking these questions:-

1. What is the function of the item?2. Is the function necessary?3. Can a lower cost standard part that serves the purpose be identified?4. To achieve a lower price, can the item be simplified, or its specifications

relaxed?5. Can the item be designed so it can be produced more efficiently or more

quickly?6. Can features that the customer values highly be added to the item?

VALUE ANALUYSIS OF ABS

Material selection

An automotive brake disc or rotor is a device for slowly or stopping the motion of the wheel. While it runs at a certain speed. The widely used brake rotor material is cast iron which consumes much fuel due to high specific gravity the material selection for the application of brake disc system emphasising on the substitution of this cast iron by any other light weight material such as cost per unit property and digital logic methods material performance requirement were analyzed and alternative solutions were evaluated among cast iron ,aluminium alloy, titanium alloy ceramic and composite mechanical property including compressive strength , wear resistance ,thermal conductivity ,specific gravity as well as cost were used as a key parameter in material strength stages. The analysis led to all metal matrix composite as a most appropriate material for brake system.

Design

An antilock brake system is designed for a specific vehicle application. A truck which

does not pull a trailer, like a cement mixer, would have a slightly different ABS than a

truck tractor which pulls one or more trailers. Likewise, an antilock brake system for a

trailer would have a different design.

ABS for automobiles may be even more specific and may be designed for a particular

Regardless of manufacturer or the type of vehicle, all antilock brake systems operate

in a similar manner. Wheel speed sensors are placed on each wheel that is to be

controlled. Each speed sensor usually has a toothed wheel that rotates at the same

speed as the vehicle wheel or axle. If the brakes are applied and one or more of the

monitored wheels suddenly begins to reduce speed at a higher rate than the others, the

controller activates the antilock system.

Since ABS components must fit and function along with existing vehicle components on each model, the design and manufacturing process of a new antilock brake system is carried out in partnership between the automobile manufacturer and the ABS supplier.

Raw Materials

The toothed wheel or gear in the speed sensor is made of soft iron, usually cast. Iron

is chosen because of its high magnetic permeability and low magnetic reluctance.

Magnetic reluctance is roughly equivalent to electrical resistance, and sometimes the

toothed wheel is called the reluctor. The function of the toothed wheel is to allow the

permanent magnet's field to easily pass through each tooth to cause a momentary

concentration of field strength which induces a current in the pick-up coil. The pick-

up coil has a permanent magnet in the core, wrapped with a coil of copper wire.

The controller usually employs transistors known as hot-side drivers which control the

power side of the circuit rather than the ground side. These transistors produce more

heat than is usual in an electronic circuit. Rather than being placed in a plastic or

stamped steel housing, they are attached to a cast aluminum housing with a finned

heat sink to dissipate the heat.

The hydraulic brake pressure solenoids used in automobiles have a standard

construction of copper coil elements with steel valves and bodies. They are housed in

the same casing as the brake system master cylinder which is usually cast from

aluminum.

The electrical wiring is copper, often with cross-linked polyethylene insulation. To

prevent radio frequency interference (RFI), in which high-power radio signals might

be received through the wiring and cause the system to activate, all wiring is either

shielded or the wires are run as twisted pairs to cancel out the effects of radio waves.

Connectors are plastic with internal copper contacts.

The Manufacturing Process

The manufacturing process for antilock brake systems consists of manufacturing the

component parts and then installing those parts on the vehicle. The parts are built in

one plant, then packaged and shipped to a vehicle assembly plant for installation. This

is a typical process for an automobile antilock brake system.

Making the master brake cylinder

The master cylinder, including the base for the solenoid body, is cast as a

single unit. The seating and sealing surfaces are machined smooth and the

connection ports are threaded.

The individual primary and secondary pistons, solenoid coils, reservoir caps

and seals, pressure accumulator, and any metering and proportioning valves

are installed. The solenoid body has a cover which attaches to the master

cylinder with four or more screws and is sealed with a gasket.

Making the wheel speed sensors

The toothed wheel is cast from iron. Minor machining may be required at the

mounting points.

The pick-up coils are wound around the permanent magnet core in a

machine called a coil winder. The entire assembly is encased, or potted, in

plastic resin with an electrical connector attached.

Making the controller

The electronic controller components are soldered to a printed circuit board.

The board is connected inside a protective housing and mounted to the cast

aluminium heat sink base. External electrical connections are provided for the

input wiring from each speed sensor and the out-put wiring to the solenoids

in the master brake cylinder.

Installing the ABS

In the automobile assembly plant, the steel tubing brake lines are installed in

the framework of the body. They run from the partition between the engine

compartment and the occupant compartment, called the firewall, to the

vicinity of each wheel. The electrical wires for the ABS are also run from the

vicinity of each wheel to the controller location and from the controller to the

firewall.

The brake master cylinder is bolted to the firewall in the engine

compartment near the brake pedal. The brake lines are attached to the

appropriate ports on the solenoid body, and the electrical wires are

connected.

The toothed sensor wheels are pressed onto the outer constant velocity

joints or the ends of the axle spindles so that they ride just inside the wheels.

Once the axles are attached to the frame, the brake lines are attached and

the pick-up coils are installed so that the end of the coils are close to the

toothed wheels. The pick-up coils are then electrically connected to the wires

to the controller.

The controller is installed either under the instrument panel or in the vehicle's

trunk. The electrical connections are made, including the power connection

from the vehicle battery through the fuse-box.

Quality Control

The idea of an electronic system being able to take over the operation of a vehicle's

brakes is disturbing to some people. For this reason, the operation of the system is

thoroughly tested beforehand, and the quality of the installation is constantly

reviewed.

In addition, all antilock brake systems are designed to be fail-safe—that is, any failure

of any component will cause the system to fail in such a manner as to still allow the

overall safe operation of the brakes.

CALCULATION

ANALYSIS OF FORCES

Forces Acting on a brake ApplicationP = Force applied at the end of lever.R= Normal force pressing the brake block on the wheel.

F= Tangential braking force or frictional force acting at the contact surface of the block.T= Braking torquer = Radius of the wheel.ø = Angle of contact surface of the block.µ = Coefficient of friction.1. F= (µ x R)

2. T= Fx r = (µ x R) x r

Case 1.When the line of action of (F) passes through fulcrum of the lever.

Then taking moment about the fulcrum ‘O’, We have

Rx X = P x L or R= (P x L) / X

T= µ x Rx r = (µ x P x L x r) / X

Case 2.When the line of action of (Ft) passes through a distance (‘a’) below the fulcrum ‘O’, then taking moment about the fulcrum ‘O’

(Rn x X) + (Fx a) = P x L

µ Or R= (P x L) / (X+x a)

T= µ x Rx r = (µ x P x L x r) / (X +µ x a)

Case 3.When line of action of (F) passes through a distance ‘a’ above the fulcrum ‘O’, then taking moments about O, we have

Rn x X = (P x L) + (Fx a) = (P x L) + (µ x Rn x a)

Rn= (P x L) / (X - µ x a)

T= µ x Rn x r = (µ x P x L x r) / (X - µ x a)

ENERGY ABSORBED BY THE BRAKECase 1.When the motion of the body is pure translation.

Change in kinetic energy of vehicle of mass (m) moving with velocity (V1) is reduced to velocity (V2),

E= ½ x m x [(V)– (V)]

If the vehicle is stopped after applying brake, then E= ½ x m x (V).

Case 2.When the motion of the body is pure rotation.

When the body of mass moment of inertia ‘I’ is rotating about an axis with angular velocity ‘v ’ is reduced to ‘ ’rad/s after applying the brake. Therefore change inkinetic energy E= I = ½ x L x [()–()]

If the rotating body is stopped after applyingE= I = ½ x L x ()

Case 3.When the motion of the body is both translation andRotation..Therefore , Total kinetic energy to be absorbed by the brake,E=E+EN1= Speed of the brake drum before brake is applied

N2= Speed of the brake drum after brake is applied

N = Mean speed of brake drum = (N1+N2)/2

Total energy absorbed by the brake must be equal to the workdone by frictional force, therefore E = (Fx px d x N x t)

Or F= E / (px d x N x t)

CASE STUDY

Q:-To stop a vehicle of 1200kg in a distance of 50m which is moving down the hill at a slope of 1:5 at 72km/h. How much would be the average braking torque required.

SOLUTION:-We have, M =1200kg; slope = 1:5; v=72km/h=20m/s; h=50m

Average braking torque to be applied to stop the vehicle We know that kinetic energy of the vehicleE=( ½ x m x V)= ½ x 1200 x (20)= 240000N-m

The Potential energy of the vehicle,FP = (m x g x h) x slope = (1200 x 9.81 x 50) x 1/5 = 117720N-m

Total energy of the vehicle or energy absorbed by the brake,E = E+ E= 240000 + 117720 = 357720N-m

Tangential braking force to stop the vehicle in a 50m distance,F= 357720 / 50 = 7154.4N

Average braking torque to be applied to stop the vehicle,T= F x r = 7154.4 x 0.3 = 2146.32N-m

STRESS ANALYSIS

Rectangular Projected Area Brake shoeWidth of Brake Shoe, W= 155mmLength of Brake shoe, L = 250mmProjected Bearing Area of brake Shoe,A = 38750mm2F= 7154.4N

Stress on brake shoe, Sb = F/ A = 7154.4 / 38750

= 0.1846N/mm2

FUTURE SCOPE

BIBLOGRAPHY

1. Bhandari V.P, Design of Machine Elements, Tata Mc Graw Hill, 11 th

Edition,2000.

2. Giri N.K , Automobile Engineering, Khanna Publications, 2 nd

Edition,2007.

Gerald J. S. Wilde , Haynes Anti lock brake system, 3 Edition,4. rd

1994.

5. www.auto.howstuffworks.com

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