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AUTOMATIC REVERSE BRAKING SYSTEM

SYNOPSIS

The technology of pneumatics has gained tremendous importance in the field

of workplace rationalization and automation from old-fashioned timber works and

coal mines to modern machine shops and space robots. It is therefore important

that technicians and engineers should have a good knowledge of pneumatic

system, air operated valves and accessories. The air is compressed in an air

compressor and from the compressor plant the flow medium is transmitted to the

pneumatic cylinder through a well laid pipe line system. To maintain optimum

efficiency of pneumatic system, it is of vital importance that pressure drop between

generation and consumption of compressed air is kept very low.

The aim is to design and develop a control system based an intelligent

electronically controlled automotive braking system is called AUTOMATIC

REVERSE BRAKING SYSTEM. This Braking system is consists of IR

transmitter and Receiver circuit, Control Unit, Pneumatic breaking system. The IR

sensor is used to detect the obstacle. There is any obstacle in the path, the IR

sensor senses the obstacle and giving the control signal to the breaking system. The

pneumatic breaking system is used to break the system.

INTRODUCTION


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We have pleasure in introducing our new project AUTOMATIC

REVERSE BRAKING SYSTEM, which is fully equipped by IR sensors circuit

and Pneumatic breaking circuit. It is a genuine project which is fully equipped and

designed for Automobile vehicles.

This forms an integral part of best quality. This product underwent strenuous

test in our Automobile vehicles and it is good.

BLOCK DIAGRAM

POWER

SUPPLY

CONTROL

UNIT

IRTRANSMITTER

PNEUMATIC

CYLINDER

SOLINOID

VALVE

BRAKE

ANGEMENT

IR RECEIVER

FLOW

CONTROL

VANVE

AIR TANK

(COMPRESSOR)


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WORKING OPERATION

The IR TRANSMITTERcircuit is to transmite the Infra-Red rays. If any

obstacle is there in a path, the Infra-Red rays reflected. This reflected Infra-Red

rays are received by the receiver circuit is called IR RECEIVER.

The IR receiver circuir receives the reflected IR rays and giving the control

signal to the control circuit. The control circuit is used to activate the solenoid

valve. If the solenoid valve is activated, the compressed air passes to the Double

Acting Pneumatic Cylinder. The compressed air activate the pneumatic cylinder

and moves the piston rod.

If the piston moves forward, then the breaking arrangement activated. The

breaking arrangement is used to break the wheel gradually or suddenly due to the

pistion movement. The breaking speed is varied by adjesting the valve is called

FLOW CONTROL VALVE.

In our project, we have to apply this breaking arrangement in one wheel as a

model. The compressed air drawn from the compressor in our project. The


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compressed air floe through the Polyurethene tube to the flow control valve. The

flow control valve is connected to the solenoid valve as mentioned in the block

diagram.

APPLICATIONS

For automobile application

Industrial application

ADVANTAGES

Brake cost will be less.

Free from wear adjustment.

Less power consumption

Less skill technicians is sufficient to operate.

It gives simplified very operation.

Installation is simplified very much.


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To avoid other burnable interactions viz. (Diaphragm) is

not used.

Less time and more profit.


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BLOCK DIAGRAM

WORKING OPERATION

BATTERY

CONTROL

UNIT

IR

TRANSMITTER

IR RECEIVER

RELAY

PERMANENT MAGNET

D.C. MOTOR


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The IR TRANSMITTERcircuit is to transmite the Infra-Red rays. If any

obstacle is there in a path, the Infra-Red rays reflected. This reflected Infra-Red

rays are received by the receiver circuit is called IR RECEIVER.

The IR receiver circuir receives the reflected IR rays and giving the control

signal to the control circuit. The control circuit is used to activate the relay, so that

motor will stop.


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BATTERIESINTRODUCTION:

In isolated systems away from the grid, batteries are used for storage of

excess solar energy converted into electrical energy. The only exceptions are

isolated sunshine load such as irrigation pumps or drinking water supplies for

storage. In fact for small units with output less than one kilowatt. Batteries seem

to be the only technically and economically available storage means. Since both

the photo-voltaic system and batteries are high in capital costs. It is necessary that

the overall system be optimized with respect to available energy and local demand

pattern. To be economically attractive the storage of solar electricity requires a

battery with a particular combination of properties:

(1) Low cost

(2) Long life

(3) High reliability

(4) High overall efficiency

(5) Low discharge

(6) Minimum maintenance

(A) Ampere hour efficiency


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(B) Watt hour efficiency

We use lead acid battery for storing the electrical energy from the solar

panel for lighting the street and so about the lead acid cells are explained below.


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2.2 CONSTRUCTION:

Inside a lead-acid battery, the positive and negative electrodes consist of a

group of plates welded to a connecting strap. The plates are immersed in the

electrolyte, consisting of 8 parts of water to 3 parts of concentrated sulfuric acid.

Each plate is a grid or framework, made of a lead-antimony alloy. This

construction enables the active material, which is lead oxide, to be pasted into the

grid. In manufacture of the cell, a forming charge produces the positive and

negative electrodes. In the forming process, the active material in the positive

plate is changed to lead peroxide (pbo). The negative electrode is spongy lead

(pb).

Automobile batteries are usually shipped dry from the manufacturer. The

electrolyte is put in at the time of installation, and then the battery is charged to

from the plates. With maintenance-free batteries, little or no water need be added

in normal service. Some types are sealed, except for a pressure vent, without

provision for adding water.

The construction parts of battery are shown in figure.


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2.3CHEMICAL ACTION:

Sulfuric acid is a combination of hydrogen and sulfate ions. When the cell

discharges, lead peroxide from the positive electrode combines with hydrogen ions

to form water and with sulfate ions to form lead sulfate. Combining lead on the

negative plate with sulfate ions also produces he sulfate. There fore, the net result

of discharge is to produce more water, which dilutes the electrolyte, and to form

lead sulfate on the plates.

As the discharge continues, the sulfate fills the pores of the grids, retarding

circulation of acid in the active material. Lead sulfate is the powder often seen on

the outside terminals of old batteries. When the combination of weak electrolyte

and sulfating on the plate lowers the output of the battery, charging is necessary.

On charge, the external D.C. source reverses the current in the battery. The

reversed direction of ions flows in the electrolyte result in a reversal of the

chemical reactions. Now the lead sulfates on the positive plate reactive with the

water and sulfate ions to produce lead peroxide and sulfuric acid.


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At the same time, charging enables the lead sulfate on the negative plate to

react with hydrogen ions; this also forms sulfuric acid while reforming lead on the

negative plate to react with hydrogen ions; this also forms currents can restore the

cell to full output, with lead peroxide on the positive plates, spongy lead on the

negative plate, and the required concentration of sulfuric acid in the electrolyte.

The chemical equation for the lead-acid cell is

Charge

Pb + pbO + 2HSO 2pbSO + 2HO

Discharge

On discharge, the pb and pbo combine with the SO ions at the left side of

the equation to form lead sulfate (pbSO) and water (HO) at the right side of the

equation.

One battery consists of 6 cell, each have an output voltage of 2.1V, which

are connected in series to get an voltage of 12V and the same 12V battery is


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connected in series, to get an 24 V battery. They are placed in the water proof iron

casing box.

D.C. MOTOR (PERMANENT MAGNET):

DESCRIPTION OF DC MOTOR

An electric motor is a machine which converts electrical energy to

mechanical energy. Its action is based on the principle that when a current-

carrying conductor is placed in a magnetic field, it experiences a magnetic force

whose direction is given by Flemings left hand rule.

When a motor is in operation, it develops torque. This torque can produce

mechanical rotation. DC motors are also like generators classified into shunt

wound or series wound or compound wound motors.

FLEMINGS LEFT HAND RULE:


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Keep the force finger, middle finger and thumb of the left hand mutually

perpendicular to one another. If the fore finger indicates the direction of magnetic

field and middle finger indicates direction of current in the conductor, then the

thumb indicates the direction of the motion of conductor.

PRINCIPLE OF OPERATION OF DC MOTOR:

Figure I show a uniform magnetic field in which a straight conductor

carrying no current is placed. The conductor is perpendicular to the direction of

the magnetic field.

In figure II the conductor is shown as carrying a current away from the

viewer, but the field due to the N and S poles has been removed. There is no

movement of the conductor during the above two conditions. In figure III the

current carrying conductor is placed in the magnetic field. The field due to the

current in the conductor supports the main field above the conductor, but opposes

the main field below the conductor.


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Movement of

Conductor

Magnetic flux current carrying

Conductor

N S


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Let's start by looking at the overall plan of a simple 2-pole DC electric motor. A

simple motor has 6 parts, as shown in the diagram below.

An armature or rotor

A commutator

Brushes

An axle

A field magnet

A DC power supply of some sort


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An electric motor is all about magnets and magnetism: a motor uses magnets

to create motion. If you have ever played with magnets you know about the

fundamental law of all magnets: Opposites attract and likes repel.

So if you have 2 bar magnets with their ends marked north and south, then

the North end of one magnet will attract the South end of the other. On the other

hand, the North end of one magnet will repel the North end of the other (and

similarly south will repel south). Inside an electric motor these attracting and

repelling forces create rotational motion.


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In the diagram above and below you can see two magnets in the motor, the

armature (or rotor) is an electromagnet, while the field magnet is a permanent

magnet (the field magnet could be an electromagnet as well, but in most small

motors it is not to save power).

.

IR SENSOR UNIT:-

The IR transmitter and IR

receiver circuit is used to sense the obstacle. It is fixed to the back side of the

frame stand with a suitable arrangement. The pneumatic cylinder is controlled by

the flow control valve, single acting solenoid valve and control unit.


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1 8

2 7

IC 5553 6

4 5

IR TRANSMITTER CIRCUIT:

+Vcc

R4 (47) T1 (BD140)

150K

3 1

2

C3 (100/25V) R1

R2 (47) 1.5K


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R5 4.7

L1 IR LED C2 C1

0.01pF 0.1pF


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L3 (LED) 1N4007 4.7K R3 R2

R7 (100K) 4.7K 4.7K

D1 (1N 4007) T3 C4 (0.1pF) C1 (0.0

T5 (BC547B) R9 (4.7K) R8 BC 557

T4 (BC 547B) T2 (BC549C)

3

120 C8 (47 pF)

R5

T1 (BC 549C)

R11 C7


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AT NORMAL CONDITION:

The IR transmitter sensor is transmitting the infrared rays with the help of

555 IC timer circuit. These infrared rays are received by the IR receiver sensor.

The Transistor T1, T2 and T3 are used as an amplifier section. At normal condition

Transistor T5 is ON condition. At that time relay is ON, so that the vehicle running

continuously.

AT OBSTACLE CONDITION:

At Obstacle conditions the IR transmitter and IR receiver, the resistance

across the Transmitter and receiver is high due to the non-conductivity of the IR

waves. So the output of transistor T5 goes from ON condition to OFF stage. In that

time the relay is OFF position. In that time, the vehicle stops.


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4.1.1 Classification of Air Compressor

The air compressor may be classified in many ways but the following are important of

view.

1. According to working

a. Reciprocating Compressor

b. Rotary Compressor

2. According to action

a. Single acting compressor

b. Double acting compressor

3. According to number of stages

a. Single stage compressor

b. Multi stage compressor:

particular size of piston diameter, rod length and stroke length.


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4.5.1. Parts of a Solenoid Valve

1. Coil

The solenoid coil is made of copper wire. The layers of wire are separated by insulating

layer. The entire solenoid coil is covered with an varnish that is not affected by solvents,

moisture, cutting oil or often fluids. Coils are rated in various voltages such as 115 volts AC,

230 volts AC, 460 volts AC, 575 Volts AC, 6 Volts DC, 12 Volts DC, 24 Volts DC, 115 Volts

DC & 230 Volts DC. They are designed for such frequencies as 50 Hz to 60 Hz.

2. Frame

The solenoid frame serves several purposes. Since it is made of laminated sheets, it is

magnetized when the current passes through the coil. The magnetized coil attract the metal

plunger to move. The frame has provisions for attaching the mounting. They are usually bolted

or welded to the frame. The frame has provisions for receivers, the plunger. The wear strips are

mounted to the solenoid frame, and are made of materials such as metal or impregnated less fiber

cloth.

3. Solenoid Plunger


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The Solenoid plunger is the mover mechanism of the solenoid. The plunger is made of

steel laminations which are riveted together under high pressure, so that there will be no

movement of the lamination with respect to one another. At the top of the plunger a pin hole is

placed for making a connection to some device. The solenoid plunger is moved by a magnetic

force in one direction and is usually returned by spring action.

Solenoid operated valves are usually provided with cover over either the solenoid or the

entire valve. This protects the solenoid from dirt and other foreign matter, and protects the

actuator. In many applications it is necessary to use explosion proof solenoids.

4.5.2. Working of Solenoid Valve

The solenoid valve has 5 openings. This ensure easy exhausting of 5/2 valve. The spool

of the 5/2 valve slide inside the main bore according to spool position; the ports get connected

and disconnected. The working principle is as follows.

Position-1

When the spool is actuated towards outer direction port P gets connected to B and S

remains closed while A gets connected to R


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Poisition-2

When the spool is pushed in the inner direction port P and A gets connected to each

other and B to S while port R remains closed.


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From the basic bridge configuration we see that two diodes are conducting while

the other two diodes are in off state during the period t = 0 to T/2 Accordingly for the

negative of the input the conducting diodes. Thus the polarity across the load is the same.

Filter:

The filter circuit used here is the capacitor filter circuit where a capacitor is

connected at the rectifier output, and a DC is obtained across it. The filtered waveform is

essentially a DC voltage with negligible ripples, which is ultimately fed to the load.

Regulator:

The output voltage from the capacitor is more filtered and finally regulated. The

voltage regulator is a device, which maintains the output voltage constant irrespective of

the change in supply variations, load variation and temperature changes. Here we use

two fixed voltage regulators namely LM 7812, LM 7805 and LM 7912. The IC 7812 is a

+12V regulator IC 7912 is a 12V regulator and IC 7805 is a +5V regulator.


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IN OUT

IC 78XX

GND

VOLTAGE REGULATOR (IC 78XX SERIES) MODEL CIRCUIT:

+ 1 2 +

CFROM (0-15V) C 470 mF 0.01 mF

RECTIFIER V = + XX V3

- -

RELAY

A relay is nothing but a switch mostly switches are manually operated type.

But the operations has not sufficient in ON and OFF purpose, it has many problems. So

we are used automatically operated switches it is worked based on the voltage across the

relay coil, an relay consist of an relay coil one pole two contact the pole is a movable one.

It is moved to new position by means of voltage is applied to the relay coil. The pole is

normally closed contact and another contact is normally opened contact.

The supply is available across the relay coil, then the normally opened contact

is closed and normally closed contact opened. The above explanations are suitable for

single pole and double through relay. The contacts are used to following of the current.

The various current ratings are available. The current rating is not available in

the market then we are assuming the total current. But the relays are not used in very high


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currents rating. Because of arcing at the time of contacts is opened. The relay contacts are

periodically checkup is required. The operations will not be followed. So the contact is

damaged on the continuous condition may gets damaged the contact, due to the heat.

SOLENOID VALVE:

In our project electrically actuated solenoid operated 5/2 DC valves are used.

Solenoid is another name for an electromagnet. Direction control valves are very often

actuated by electromagnets. An electromagnet is a temporary magnet. A magnetic force is

developed in an electromagnet when electrical current passes through it and force drops down as

soon as it is de energized.

This electromagnet is commonly termed as solenoid. The proper working of a solenoid

operated valve depends on the reliability of the electromagnets.

It ensures

Quick and sure action


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Long life.

Easy maintenance.

Less wastage of energy.

INTRODUCTION:

The directional valve is one of the important parts of a pneumatic system. Commonly

known as DCV, this valve is used to control the direction of air flow in the pneumatic system.

The directional valve does this by changing the position of its internal movable parts.

This valve was selected for speedy operation and to reduce the manual effort and also

for the modification of the machine into automatic machine by means of using a solenoid valve.

A solenoid is an electrical device that converts electrical energy into straight line motion

and force. These are also used to operate a mechanical operation which in turn operates the

valve mechanism. Solenoids may be push type or pull type. The push type solenoid is one in

which the plunger is pushed when the solenoid is energized electrically. The pull type solenoid

is one is which the plunger is pulled when the solenoid is energized.


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The name of the parts of the solenoid should be learned so that they can be recognized

when called upon to make repairs, to do service work or to install them.

Parts of a Solenoid Valve

4. Coil

The solenoid coil is made of copper wire. The layers of wire are separated by insulating

layer. The entire solenoid coil is covered with a varnish that is not affected by solvents,

moisture, cutting oil or often fluids. Coils are rated in various voltages such as 115 volts AC,

230 volts AC, 460 volts AC, 575 Volts AC, 6 Volts DC, 12 Volts DC, 24 Volts DC, 115 Volts

DC & 230 Volts DC. They are designed for such frequencies as 50 Hz to 60 Hz.

5. Frame

The solenoid frame serves several purposes. Since it is made of laminated sheets, it is

magnetized when the current passes through the coil. The magnetized coil attracts the metal

plunger to move. The frame has provisions for attaching the mounting. They are usually bolted

or welded to the frame. The frame has provisions for receivers, the plunger. The wear strips are

mounted to the solenoid frame, and are made of materials such as metal or impregnated less fiber

cloth.


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