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Chapter Chapter 3 3 ELECTRO PNEUMATIC ELECTRO PNEUMATIC SYSTEM SYSTEM Industrial Electronics DEK 3113

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Chapter 3Chapter 3

ELECTRO PNEUMATIC ELECTRO PNEUMATIC SYSTEMSYSTEM

Industrial Electronics

DEK 3113

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Intro of Electro-pneumatic system

Pneumatic products represent a multi-billion dollar industry today.

Pneumatic devices are used in many industrial applications.

Most pneumatic devices are designed to use clean dry air as an energy source.

The actuator then converts that compressed air into mechanical motion. The type of motion produced depends on the design of the actuator.

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Into of electro-pneumatic system

-Electro pneumatic system consist of both electrical and pneumatic system.-Usage of electro pneumatic includes:1) Packaging2) Stamping, shearing & embossing part3) Sorting part4) Component stacking5) Material stacking

-Electro pneumatic system consist of both electrical and pneumatic system.-Usage of electro pneumatic includes:1) Packaging2) Stamping, shearing & embossing part3) Sorting part4) Component stacking5) Material stacking

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Example of pneumaticconnections/diagram:

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Example of electrical wiring/connection

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Solenoid symbol which moves the valve.

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Directional Control Valve: Port & Position

-directional control valve is attach with

solenoid, so that it can move forward &

backwards.

-the movement of the valve is allow

compressed air go into the airway of the

valve to control the movement of the

cylinder.

-directional control valve is attach with

solenoid, so that it can move forward &

backwards.

-the movement of the valve is allow

compressed air go into the airway of the

valve to control the movement of the

cylinder.

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Directional Control Valve: Port & Position..cont

i) Valve switching positions are represented by squares

ii) The number of switching positions of the valve is

shown by the number of squares

iii) Lines indicates arrow show the direction of flow

paths

iv) Shut off positions are identified in the boxes by lines

at right angles

v) The connection (inlet and outlet ports) are shown by lines on the outside of the box and are drawn in the initial position.

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Several type of valve

Port or

connection

DIN ISO 5599

LetteringSystem

Pressure port 1 P

Exhaust port 3 R

Exhaust ports 5,3 R,S

Signal outputs

2,4 B,A

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Numbering system for pneumatic circuit element

0.1 Air supply unit1.0, 2.0 etc Working element (cylinder)1.1,2.1 etc Control Element (solenoid)1.01,1.02 etc Element btwn control element & working element- one way flow control valve

0.1 Air supply unit1.0, 2.0 etc Working element (cylinder)1.1,2.1 etc Control Element (solenoid)1.01,1.02 etc Element btwn control element & working element- one way flow control valve

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Control of single acting cylinder-rest position, air supply shut off, cylinder retracted by the spring.-when switch closed, current flow to the circuit & start to energize solenoid coil-Magnetic field created, push the plunger that will slide the valve to the right. -This will allow the air to flow

inside the piston & extend the piston.-If switch released, the valve will slide back & cause the air to stop.

-rest position, air supply shut off, cylinder retracted by the spring.-when switch closed, current flow to the circuit & start to energize solenoid coil-Magnetic field created, push the plunger that will slide the valve to the right. -This will allow the air to flow

inside the piston & extend the piston.-If switch released, the valve will slide back & cause the air to stop.

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Control of double acting cylinder

-rest [

-rest position, air supply flowing to the cylinder piston rod via the valve and pushing the piston at rest/retraction position-no current flow to the solenoid-switch closed, energized solenoid coil-magnetic field develop at solenoid.-magnetic filed develop push the plunger and cause valve slide to the right.-this allow air flow inside the piston via the other port & push/extend the valve.-when switch released, current not flow, cause the magnetic field weaker and vanish-valve slide to initial position.

-rest position, air supply flowing to the cylinder piston rod via the valve and pushing the piston at rest/retraction position-no current flow to the solenoid-switch closed, energized solenoid coil-magnetic field develop at solenoid.-magnetic filed develop push the plunger and cause valve slide to the right.-this allow air flow inside the piston via the other port & push/extend the valve.-when switch released, current not flow, cause the magnetic field weaker and vanish-valve slide to initial position.

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Basic circuit for electro pneumatic circuit1) AND 2) OR 3) NOT

4) Memory latching

5) Dominant reset

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Cont..

6) Dominant set

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Process Sequence Description

There are several method to describe

process sequence:

1) Simple narative

2) Boolean

3) Grafset

4) Motion diagram

5) Displacement diagram

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Simple narrative

A push button is used to turn on the conveyor belt A that brings the bottles to the filing line. Sensor 1 that is placed at the center of the conveyor A will stop the conveyor belt A upon detecting the bottle and open the valve for filing for 2 second. After that the conveyor belt will be on again until the bottle is sensed by sensor 2 at the end of conveyor belt A. Conveyor belt A once again stop and the solenoid is energized for 3 seconds in order for the piston to push the bottle to conveyor belt B. The process repeats until stop button is pressed.

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cont..

1st: please identify input and output

Input: PB,Sensor 1,timer 1 contact(2

sec),sensor 2,timer 2 contact(3

sec)

Output:Conveyor A,valve,timer 1

coil(2 sec), solenoid,timer 2

coil(3 sec)

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Cont.

2nd: Please simplified the narrative statement

1) PB turns on conveyor A2) Sensor1 stop conveyor A,open valve,timer 1 on for 2

sec3) After timer 1 times up(after 2 sec),conveyor A on.4) Sensor 2 stops the conveyor,energize solenoid,timer 2

on for 3 sec.5) Timer 2 times up(after 3 sec),conveyor A on again.6) Stop button reset all

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Boolean

1) Another one method to describe process sequence.

2) Is a logic expression using gates.

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cont

Example: The door of the automatic train will be locked if start button is

pushed and will unlocked when sensor 1 detects it’s arrival at station 1. Sensor 2 that is placed at the entrance door of the train will count the number of train passengers on that day.

D= door ; D = lock , D’ = unlock S1 = sensor 1 ; S1 = sense , S1’ = not sense S2 = sensor 2 ; S2 = sense , S2’= not sense SB = start button ; SB = pressed ,SB’ = not pressed CNT = counter ;RB=reset button ;RB=reset, RB’=not reset Boolean: 1. D = SB.S1’ D’=SB’.S1 2. CNT = S2.S1.RB’

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Grafset

Example:

The tank system has the narrative description below:

Fill the tank to level A from valve A

Fill the tank to level B from valve B

Start a timer, heater and stirrer for 5 minutes.

Open output valve C until the empty switch engages.

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Cont.

I/O assignment: input output LA - level A VA –valve A LB - Level B VB – valve B ES – empty switch VC – valve C TIM – timer contact(5 mins) TIM – timer coil(5 min) - times up after 5 min. - timer on for 5 min.

SB - start button H – heater ST - stirrer

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cont

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Motion Diagram

1) The input and the output are separated with the input at the upper side and the output is at the bottom side.

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Displacement Diagram

1) Presented in form of graph indicates the position of the cylinders and the displacement Step 1 : Cyl1 and Cyl 2 extend

Step 2 : Cyl 1 retracts while Cyl 2 remains

extend for 3 seconds.

Step 3 : Cyl 1 remains retracts for 3 seconds

and Cyl 2 retracts

Step 4 - step 6 : The position of Cyl 1 and Cyl 2 similar as Step 1 – Step 3

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Con.

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Single Acting Cylinder

(a) Spring Retracted Type: A spring retracted single acting cylinder develops thrust in one direction only. The piston rod is returned by the spring

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Cont’d…

1- Piston

2- Piston rod

3- Return Spring

4- Rod Cover

5- Head Cover

6- Piston Seal

7- Stopper Spring

8- Guiding Ring

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Cont’d…

When compressed air is supplied to the air port, the compressed air will act on the piston extending the piston rod

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Cont’d…

When the compressed air is allowed to vent out of the air port, the spring force will retract the piston rod

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Single Acting Cylinder

(b) Spring Extended Type: A spring extended single acting cylinder develops thrust in one direction only. The piston rod is extended by the spring

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Cont’d…

1- Piston2- Piston rod3- Return Spring4- Rod Cover5- Head Cover6- Piston Seal7- Stopper Spring8- Guiding Ring

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Cont’d…

When compressed air is supplied to the air port, the compressed air will act on the piston retracting the piston rod

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Cont’d…

When the compressed air is allowed to vent out of the air port, the spring force will extend the piston rod

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Double Acting Cylinder

A double acting cylinder develops thrust in both extending and retracting directions as air pressure is applied alternately to opposite sides of a piston

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Cont’d…

1- Piston

2- Piston Rod

3- Rod Cover

4- Head Cover

5- Piston Seal

6- Rod Seal

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Cont’d…

The piston rod is pushed out when compressed air goes in the inlet of the head cover.

If the compressed air goes in the inlet of the rod cover and the air in the inlet of the head cover is exhausted, the piston rod is pushed back to its original position

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VALVES

A directional control valve determines the flow of air between its ports by opening, closing or changing its internal connections

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2/2 Valve

To drive air motors and pneumatic tools

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3/2 Normally Closed Valve

Used to drive single acting cylinders or act as an on/off switch

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3/2 Normally Open Valve

Used to drive single acting cylinders

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4/2 Valves

To drive double acting cylinders, with a common exhaust

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5/2 Valves

To drive double acting cylinders with individual exhaust

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5/3 Exhaust Center

To drive double acting cylinders with the possibility of stopping the cylinder in any position

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5/3 Closed Center

To drive double acting cylinders with the possibility of stopping the cylinder in any position

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5/3 Pressure Center

Used to drive double acting, through rod cylinder with the possibility of stopping the cylinder in any position

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Example 1

The opening and closing the door (similar to bus door) is controlled by using single acting cylinder. The opening of the door is activated by using push button switch PB1. Means, when PB1 is pressed, the door is open (Cylinder start to extend). LS1 will detect the full extension of cylinder. (Door is fully open). The door remains open for 10 sec before it is automatically closed.Note: Use 3/2 way valve normally close. Assume traveling time for cylinder from original position to full extension (or vice versa) is 1 sec.1) Please list out input and output.2) Please draw grafset3) Please draw motion diagram4) Please draw displacement diagram.5) Please draw pneumatic and circuit diagram

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Example 2

The opening and closing the door (similar to bus door) is controlled by using double acting cylinder. The opening of the door is activated by using push button switch PB1. Means, when PB1 is pressed, the door is open (Cylinder start to extend). LS1 will detect the full extension of cylinder. (Door is fully open). The door remains open for 10 sec before it is automatically closed.Note: Use 5/2 way directional valve. Assume traveling time for cylinder from original position to full extension (or vice versa) is 1 sec.1) Please list out input and output.2) Please draw grafset3) Please draw motion diagram4) Please draw displacement diagram.5) Please draw pneumatic and circuit diagram

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Exercise 1

A single acting cylinder will extend whenpush button(PB) is pressed and will retractwhen PB is released.(i. Assume travelling time for single acting cylinder to move from initial position to full extension/full retraction is 2 sec ii. Use 3/2 valve NC)

1) Please list out input and output.2) Please draw grafset3) Please draw motion diagram4) Please draw displacement diagram.5) Please draw pneumatic and circuit diagram

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Exercise 2

A single acting cylinder will extend when push button(PB) is pressed and will retract when the extension position isdetected by Limit switch 1(LS1)(Assume travelling time for single acting cylinder to move from initial position to full extension/full retraction is 2 sec)

1) Please list out input and output.2) Please draw grafset3) Please draw motion diagram4) Please draw displacement diagram.5) Please draw pneumatic and circuit diagram

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Exercise 2-1

A single acting cylinder will extend when push button(PB) is pressed and will start toretract when it reach full extension position.(Assume travelling time for single acting cylinder to move from initial position to full extension/full retraction is 2 sec)

1) Please list out input and output.2) Please draw grafset3) Please draw motion diagram4) Please draw displacement diagram.5) Please draw pneumatic and circuit diagram

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Exercise 3

A single acting cylinder will extend whenpush button (PB) is pressed. A lamp will on when the piston has extended 15mmfrom the initial position (detected by limit switch 1(LS1)). The piston will retract to its initial position and the lamp will off after 4 second.(Assume travelling time for single acting cylinder to move from initial position to full extension/full retraction is 2 sec)

1) Please list out input and output.2) Please draw grafset3) Please draw motion diagram4) Please draw displacement diagram.5) Please draw pneumatic and circuit diagram

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Exercise 4

PB will cause cyl. 1 extend until LS1 detect which cause cyl. 2 extends too.LS2 at the end of cyl. 2 will cause timer to activate for 10 sec. After 10 sec the lamp will on and at the same time cyl. 1 and cyl. 2 will retractIt use single acting cyl. & 3/2 way NC valve.(Assume travelling time for cyl 1 and cyl 2 from it fullretract to it full extend or vice versa is 1 sec)

1) Please list out input and output.2) Please draw grafset3) Please draw motion diagram4) Please draw displacement diagram.Need to mention the exact

time it need to extend and retract.5) Please draw pneumatic and circuit diagram

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Exercise 4-1

PB will cause cyl. 1 extend until LS1 detect which cause cyl. 2 extends too. At it full extension, it will cause timer to activate for 10 sec. After 10 sec the lamp will on and at the same time cyl. 1 and cyl. 2 will retractIt use double acting cyl. & 5/2 way valve.(Assume travelling time for cyl 1 and cyl 2 from it fullretract to it full extend or vice versa is 1 sec)

1) Please list out input and output.2) Please draw grafset3) Please draw motion diagram4) Please draw displacement diagram.Need to mention the exact

time it need to extend and retract.5) Please draw pneumatic and circuit diagram

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6. When PB is pressed, after 5 sec cylinder A will extend. At it full extension, cylinder A will hit LS1 and caused timer to activate for 5 second before cylinder B start to activate. LS2 will detect the full extension of cylinder B and remain at it full extension for 5 second before cylinder A and B retract. When cylinder A at it full retraction, it will hit LS3 which cause lamp to activate for 2 second. Note: Cylinder A and B use single acting cylinder. Use 3/2 ways valve normally close. Assume traveling time for cylinder A and B from its origin to full extension or vice versa is 2 second.

1. Draw grafset and motion diagram.2. List out input and output.3. Draw displacement diagram.4. Draw pneumatic and circuit diagram.

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7. In order to drill piece of wooden block, we need to use double acting cylinder A, B and C (5/2 way valve). When PB is pressed, cylinder A will push the wooden block until wooden block is detected by LS2 which cause cylinder C extend to hold the wooden block from move. When cylinder C at it full extension, cylinder B will extend. When LS3 detect the full extension of cylinder B, it will start doing drilling process for 10 sec. When finished drilled (after 10 sec), cylinder B will retract. When cylinder B is fully retract, cylinder A and cylinder C will start to retract.

(Note: : Assume traveling time for cylinder A, B, C from origin state to full retraction/full extension is 2 second) : Solenoid for valve A (cylinder A)-Y1 and Y2 : Solenoid for valve B (cylinder B) -Y3 and Y4 : Solenoid for valve C (cylinder C) -Y5 and Y6

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When PB is pressed, the robot hand move downwards until it detect by down

sensor. Then, the gripper start to grip the “Load” until it is detected by grip sensor.

After that, robot hand move upwards until it is detected by up sensor. Then, it move

towards right until it reach the most right position as shown in Figure 2 above.

After that, the robot hand move downward until it detect by down sensor. Then, the

gripper start to ungrip (release) the load until it detect by ungrip sensor. Then, it

move upwards until it detect by up sensor. Finally, the robot hand will moves to its

original position (most left position).

Cartesian Robot as shown above is used to transfer “Load” from point A

to point C.

It uses 3 different cylinders:

Double Acting Cylinder (5/2 way valve) : Move down (activate Y1) and up robot

hand (activate Y2).

Single Acting Cylinder (3/2 way valve NC): Grip (activate Y3) and ungrip the load.

Single Acting Cylinder (3/2 way valve NC): Move right (active Y4) and left

robot hands.

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Assume: Time for cylinder to move from up to down (or vice versa) is 2 sec.Time for cylinder to grip/ungrip the “Load” is 0.5 sec.Time for cylinder to move from right to left (vice versa) is 5 sec.Next action will not be executed unless previous action is executed

first.

1) Draw pneumatic diagram(de-energize & energize state for DOUBLE ACTING CYLINDER only) 2) Draw a motion diagram 3) Draw displacement diagram(Cylinder A,B and C)

Please include all traveling time in your diagram 4) Draw electric diagram

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