Electro-Pneumatics Basic Level Compilation

Exercise 1: Realising a sorting device

Training aims • To familiarise yourself with the design and mode of operation of a single-acting cylinder. • To familiarise yourself with the design and mode of operation of a 3/2-way solenoid valve. • To be able to identify and draw various types of actuation of directional control valves. • To be able to explain and design an example of direct actuation.

Problem definition

A sorting device is to be used to sort water samples according to the size of the sample bottle. Design a control system whereby this process can be carried out.

Parameters • A single-acting cylinder is to be used. • The control of the cylinder is to be effected by means of a pushbutton. • In the event of a power failure the cylinder piston rod is to return into the retracted end position.

Project task

1. Answer the questions or carry out the exercises regarding the fundamentals of the training contents listed. 2. Draw the pneumatic and electrical circuit diagram.

3. Simulate the electropneumatic circuit diagram and check its correct functioning. 4. Compile an equipment list. 5. Carry out the pneumatic and electrical circuit assembly. 6. Check the circuit operation.

Positional sketch

Sorting device

1. Pressing of a pushbutton causes the piston rod of a single-acting cylinder to push the sample bottle off the conveyor. 2. When the pushbutton is released, the piston rod is to return into the retracted end position.

Fundamentals: Function of pneumatic working components

Pneumatic working components can be divided into two groups: • Working components using linear movement • Working components using rotary movement – Describe the function of the working components shown.

Single Acting Cylinder Normally Extended

Single Acting Cylinder Normally Retracted

Rotary Actuator

Fundamentals: Completing solenoid valve symbols – Complete the individual symbols with the help of the corresponding component

Fundamentals: Normal positions of directional control valves

An electrically actuated 3/2-way solenoid valve has two switching positions. It can be in the normal position (unactuated) or in the switching position (actuated). In the normal position the valve can be open or closed. – Describe the effects on the motion sequence of the following application arising as a result of the different normal positions. The single-acting cylinder shown is controlled by an electrically actuated 3/2-way solenoid valve.

If the electricity flows and actuates the 3/2 way valve compress air will flow to the single acting cylinder.

If the electricity flow is stopped, the 3/2 way valve will return to its original position and stop the compress air flowing through the single acting cylinder.

Fundamentals: Direct and indirect actuation An electrically actuated solenoid valve can be actuated either directly or indirectly. – Describe the difference with the help of the following application: Electrical actuation of a spring-returned 3/2-way solenoid valve using a pushbutton.

Electricity is connected directly to the solenoid valve without the use of relays.

Electricity is connected to relays then connected to solenoid valve.

Design and function of an electrical switch Switches are basically divided into pushbutton and control switch designs and perform the function of a normally open or normally closed contact or changeover switch. – Describe the design and function of the switches shown.

Make switch with push button - if the buttons is activated the circuit will be closed as long as it is still pushed.

Break switch with detent push button – if the button is pushed the circuit will be open, if the button is released it is still open circuit until the button is push again.

Change over with push button - if the button is pushed the circuit will change to another circuit.

Fundamentals: Mode of operation of different valve types Electrically actuated directional control valves are switches with the help of solenoids. Basically, these can be divided into two groups: • Spring-return solenoid valves

• Double solenoid valves – Describe the differences between the two groups with regard to function and behaviour in the event of power failure.

A valve that has a spring-return that can return to its original position without the compressed air.

A valve that needs compressed air so that it can return to its original position.

Fundamentals: Port designations of valves

In order to prevent incorrect tubing up of directional control valves, the valve ports (working and pilot lines) are identified in accordance with ISO 5599, both on the valve itself and in the circuit diagram. – Describe the meaning and function of the designations below.

Exhaust

The one that actuates

The one that actuates also

Exercise 2: Realising a shut-off device

Compare these two valve types (directly actuated valve and pilot actuated valve) and describe the respective advantages and disadvantages: 

Directly actuated valve – A directly actuated valve is when the push button is pressed, current flows directly to the valve solenoid, allowing the directional control valve to be turned on.



Pilot actuated valve – A pilot actuated valve uses a relay to indirectly turn on the directional control valve. When the push button is pressed, the current passes through the relay first (which lowers the amount of current that passes through) and will then pass through the valve solenoid to turn the circuit on.

Describe the meaning and function of the designations below: 

4 – port connected to the closed end of the cylinder. Air is exhausted when the cylinder is retracted and the air flows through here to extend the cylinder.



14 – a port for a double-piloted direction control valve wherein when air flows through here, it changes its state (left side of valve) where air flows through (4) and exhausts through (2). It will stay at this state until it is turned off and when port 12 (right side) is turned on.



82/84 – two electromagnetic pilot valves for operating a Valve 10’

Describe the mode of operation of the directional control valve shown: 4

2

1M1 5

3 1

-

The control valve shown is to be actuated by means of a valve solenoid (with or without the use of a relay). When the pushbutton is pressed, current will flow through the valve solenoid which will then allow the compressed air to pass through, and thus allowing the cylinder to function. Since it is spring returned, it will go back to its original state when the pushbutton is released.

Describe the meaning of the cylinder symbol shown: A double acting cylinder connected to port 4 (left closed end) and port 2 (right open end). In a retracted position, air enters through (2) and exhausted at (4). In an extended position, air flows through (4) and exhausted at (2).

The right double acting cylinder has the same function as the one above. The left one is connected differently. At the retracted position, air flows through (4) and exhausts at (2). At the extended position, air flows through (2) and exhausts at (4). Designing the pneumatic and electrical circuit diagram

Equipment list: -

Double acting cylinder

-

One way control valve (2)

-

Directional control valve, spring returned

-

Valve solenoid

-

Pushbutton, normally open

EXERCISE 3: REALISING A LID PRESS

Training aims: 

To familiarize yourself with the design and mode of operation of a double-acting cylinder.



To be able to explain and design an example of an indirect actuation.

Problem definition: 

In a filling plant, wall or ceiling paints are filled into plastic pots. Once filled, sliplids are to be pressed onto the plastic pots.



A double acting cylinder is to be used.



The cylinder control is to be effected indirectly and by means of a pushbutton. In the event of power failure the cylinder piston rod is to return into the retracted end position.

Project Task 1. Answer the questions or carry out the exercises regarding the fundamentals of the training contests listed. 2. Design the pneumatic and electrical circuit diagrams 3. Simulate the electro pneumatic circuit diagram and check its correct functioning 4. Compile an equipment list 5. Carry out the pneumatic and electrical circuit assembly. 6. Check the circuit operation.

Filling of pots of paint. 1. Pressing of a pushbutton is to cause the pressing ram to advance and the slip-lid to be pressed on. 2. Once the pushbutton is released, the pressing ram is to be returned into the initial position. A relay is a remotely controlled electromagnetically actuated switch with several contacts. The main components are: 

Coil with core



Winding of coil



Contact set



Return spring



Amature



Terminal lugs

Exercise 3: Releasing a lid press -describe the mode of operation of a relay 

A relay passes on signals to a specified part of a circuit which may be a switch or an actuator. Passing on signals may turn on/off the connected electrical/pneumatic component.

One or several contacts can be switched by a relay coil. Relays with normally closed, normally open or changeover contact(s) are used depending on the function required. Additional designs of the electromagnetically actuated switches are for instance a remanence relay, the time relay with switch-one delay, the time relay with switch-off delay and the contactor. -describe the design and contact alignment of the relays show

1. This relay shows that you have two normally open switches and two normally closed switches. When there is power running

from A1 to A2, normally open switches will close and normally closed switches will switch on 2. This relay has 4 changeover contacts. This means that when power is running from A1 to A2, switches will change from the left contact to the right. -list the possible applications of relays in electrical or electropneumatical control systems. 

Relays can easily pass on signals from circuits to their pneumatic counterparts.



Relays may also be used for continuous or a constant repetition of the electropneumatic circuit’s operation.



Relays make possible the timing and delay of most actions done by pneumatic parts connected to electronic controls.

-Design the pneumatic and electrical circuit diagrams for the lid press

Pneumatic Circuit Diagram:

Electrical Circuit Diagram: Apart from the circuit diagram, comprehensive project documentation also requires an equipment list -compile the equipment list by entering the required equipment in the table below. Quantity

Description 1

double Acting cylinder

2

one-way flow valve

1

5/2-way solenoid valve

1

relay

1

solenoid valve

1

push-button

1

make-switch

In industrial practice, there are numerous different requirements with regard to a valve. If a valve with all the required features is not available, it is often possible to use a valve

with a different number of ports. The table below lists a selection of directional control valves frequently in use in industrial applications. -

Describe the valve types shown.

-

Identify all solenoid valves that can be replaced by a 5/2 – way solenoid valve of the type shown.

-

If measures are required to convert the valve, describe these.

Symbol

Description of valve

Replacement

Necessary

type

possible

Conversions

2/2 – way pilot

NO

N/A

YES

Seal work port 2

control solenoid valve w/ manual override, spring return, NC 3/2 – way pilot control solenoid

and 3

valve w/ manual 3/2-way solenoid v alv e

override, spring return, NC 3/2 – way pilot

YES

control solenoid

Seal work port 4 and 5

valve w/ manual 3/2-way solenoid v alv e

override, spring return, NO 4/2 – way pilot control solenoid valve w/ manual override, spring return

YES

Seal work port 1

Select a valve and explain the reason for your decision. Valve: Pilot actuated, spring – return 3/2 – way solenoid valve w/ manual override Reason: The solenoid valve chosen could be used as a substitute for lesser port valves, such as the 4/2 and 3/2 way valves mentioned earlier. Choosing otherwise would mean that should the user require a valve with more ports than the 3/2 way valve, an additional purchase would have to be made, increasing costs.

Function Table S1

S2

1M1

1V1

0

0

0

0

0

1

1

1

1

0

1

1

1

1

1

1

Symbol TO BE PLACED

Pneumatic Circuit Diagram:

1

2

3

4

3

3 K1

K2

2

S2

S1 3

4

K3

4

4

4

4

3

3

1

K1 4

4

A1

2 K3

A1

A1

K1

K2

1M1

1S1 5

A2

A2

A2

5

1 6

4

3 1

5

Electrical Circuit Diagram: 1

2

3

4

3

3 K1

K2 3

3

2

S2

S1 3

4

4

4

4 4

K3 1

K1 4

A1

2 K3

A1 K1

3

A1 K2

1M1

A2

A2

A2

5

1 6

4

1

5

Equipment list: 1 5/2 way pilot control solenoid valve with manual override, spring return 1 one way flow control valve 1 compressor 3 relays

2 make – push buttons

Experiment 5: Realising a diverting device

Application 1 Valve type: valve with double solenoid Reason: no need to hold button for it to stay in its position

Application 2 Valve type: valve with spring return Reason: so it returns automatically after ejecting

It works similary to a 5/2 way valve but it is double electrically piloted (double solenoid). It goes to the direction depending on which solenoid actuates it.

Answer: v=Ir

24V/48ohms = 0.5 amps

The current consumption in 1M1 will be identical even if it uses 24V AC instead of 24V DC because their voltage rating is the same.

1 double acting cylinder 2 one way flow control valve 1 5/n way valve 2 push button 2 make switch 2 relay 2 valve solenoid Exercise 6: Actuation of a Stacking Magazine

Manually Operated Push Button – Pneumatic Circuit Diagram Cylinder – Pneumatic Circuit Diagram Valves – Pneumatic Circuit Diagram Valve Coils – Pneumatic Circuit Diagram

Relays – Electrical Circuit Diagram Electromechanical limit switch – Electrical Circuit Diagram Electronic Proximity Sensor – Electrical Circuit Diagram Indicating Device – Electrical Circuit Diagram

Description function of Electromechanical switch: -

If the cylinder hits the roller of the limit switch, it will release an electric signal.

Limit switch normally closed - if the roller is hit the circuit will be opened.

Limit switch normally open - if the roller is hit the circuit will be closed.

Normally Open path 11, 12, 18

11 12 18

Normally Open path 17 Normally Close path 10, 18 10 17 18

19

X

20

X

26

X

24 21

X X

12

X

26

X

Equipment List: 1 - Double Acting Cylinder 2 - One way flow control valve 1 - 5/2 way solenoid valve 1 – Push button 1 – Magnetic Proximity Switch

EXERCISE 7: Sorting of Packages Training aims: 

To be able to calculate piston forces according to specific values



To be able to calculate electrical characteristic values



To be able to explain and design an example of indirect actuation



To familiarize yourself with logic functions and to be able to design these.

Problem definition: Packages are to be transported on a conveyor past workstations. The packages can be diverted by means of deflectors. Parameters 

A double-acting cylinder is to be used.



The cylinder control is to be effected indirectly via pushbuttons and electromechanical limit switches.



Triggering of the advancing movement is to be possible only if the piston rod is in the retracted end position.

Project Task 7. Answer the questions or carry out the exercises regarding the fundamentals of the training contests listed. 8. Design the pneumatic and electrical circuit diagrams 9. Simulate the electro pneumatic circuit diagram and check its correct functioning

10. Compile an equipment list 11. Carry out the pneumatic and electrical circuit assembly. 12. Check the circuit operation.

Sorting of Packages. 3. The piston rod of a cylinder is to advance automatically as pushbutton S1 is actuated 4. If the pushbutton is no longer actuated, the piston rod is to assume the retracted end position.

The piston of the double-acting cylinder has a diameter of 16mm and the piston rod a diameter of 8mm. The frictional losses within the cylinder are 10%. The following applies for double acting cylinders: Advance stroke

(

)

Return Stroke

(

) ( ) (

(

) (

)

)

(

)( ) ( ) ( )

-

Calculate the effective piston force in the advance and return strokes at an operation pressure of 6 bar (600 kPa)

(

)

(

)

Advance stroke = 108.573Mpa ( (

)

)

( (

)

)

Return stroke = 81.430Mpa

A relay in an electropneumatic circuit is designated as follows: 580Ω, 1 W. -

Calculate the permissible operating voltage which ensures that no overload occurs on the relay.

Max. Operating Voltage:

V = 24.08 Volts or approx. 25 Volts

Triggering of the advancing movement of the piston rod of a cylinder is to be achieved by means of two pushbuttons S1 and S2. The valve coil of 1M1 is energized if both pushbuttons are actuated simultaneously and the solenoid valve 1V1 switches into the actuated position causing the piston rod to advance. If at least one of the two

pushbuttons is released, the valve switches into the initial position and the piston rod retracts. -

Create an appropriate function table and the logic symbol. Note 0 means: Pushbutton not actuated, i.e. piston rod not advancing 1 means: pushbutton actuated, i.e. piston rod advances. S1

S2

1M1

1V1

0

0

0

0

0

1

0

0

1

0

0

0

1

1

1

1

-Design the pneumatic and electrical circuit diagrams for the lid press Pneumatic Circuit Diagram:

Electrical Circuit Diagram:

Apart from the circuit diagram, comprehensive project documentation also requires an equipment list -compile the equipment list by entering the required equipment in the table below. Quantity

Description 1

double Acting cylinder

2

one-way flow valve

1

5/2-way solenoid valve

3

relay

2

solenoid valve

1

push-button

1

make-switch

1

Detent make-switch

1

Detent break-switch

1

Break switch

Exercise 8: Actuation of a sliding platform

Training aims

To familiarize yourself with logic functions and to be able to

design these To be able to explain and design electrical latching circuits with dominant switch-off signal

Problem definition Wooden boards are to be manually placed onto a sliding platform. The boards are to be pushed under a belt sanding machine by means of a pneumatic device.

Parameters

A double-acting cylinder is to be used. The cylinder control is to be effected indirectly.

Project task

1. Answer the questions or carry out the exercises regarding the fundamentals of the training contents listed. 2. Design the pneumatic and electrical circuit diagrams. 3. Simulate the electro-pneumatic diagram and check its correct functioning. 4. Compile the equipment list. 5. Carry out the pneumatic and electrical circuit assembly. 6. Check the circuit operation.

Exercise 8: Actuation of a sliding platform

Sliding platform 1. The piston rod of a cylinder is to advance if pushbutton S1 is actuated. 2. The actuation of a pushbutton S2 is to cause the piston rod to retract.

The actuation of the pushbutton must be stored if the piston rod of a cylinder is to also advance if the pushbutton is only briefly actuated. This signal storage can be effected either in the power section or in the signal control section of a circuit. - Describe how signal storage is devised in the power section or in the signal control section respected.

Place of signal storage

Description: Signal storage

Signal storage in the

The power is stored by means of a normally closed switch. Power will be distributed if the cylinder is actuated if the pushbutton is

power section

pressed.

Signal storage in the

The signal control is stored by means of a self-sustaining circuit.

signal control section

Power is distributed through relays and changeover switches.

- Describe the behavior of the circuit specified (pilot-actuated, spring-return 5/2-way solenoid valve with manual override, doubleacting cylinder) in the event of - Power failure

- Pressure failure

Power failure

Pressure failure

The actuated switching position

Pressure is achievable when the

is only retained as long as

electro-pneumatic circuit is

electrical current flows through

connected properly, otherwise a

flows through the solenoid coil.

short circuit will occur. Pressure

The normal position is clearly

will also be achievable if the

defined by the reset spring. If

pneumatic circuit is connected

there is no electrical power, the

properly, otherwise, the air from

valve returns to its normal

the compressor will continuously

position by the spring.

flow to the cylinder.

The lamp is to be illuminated whenever pushbutton S1 is not actuated.

- Draw the appropriate function table. 0 means: Pushbutton S1 not actuated, i.e. lamp P1 off 1 means: Pushbutton S1 actuated, i.e. P1 illuminated

S1 P1 0

0

1

1

1

0

0

0

Apart from the circuit diagram, comprehensive project documentation also requires an equipment list.

- Compile the equipment list by entering the required equipment in the table below.

Quantity Description 1 Compressor 1 Air service unit 5/2 way solenoid valve spring1 returned 2 One-way flow control valve 1 Double-acting cylinder 1 Pushbutton (make) 1 Pushbutton (break) 3 Changeover switch

Exercise 9: Expanding a diverting device The relay K1 is energized by actuating pushbutton S1. Complete the electrical circuit diagram below so that the relay latches after S1 is released.

1

+24V

2

S1

K1

K1 0V

2

Complete the electrical circuit diagram so that the self-latching loop is reliably cancelled via actuation of a pushbutton S2.

1

+24V

2

S1

K1

S2

K1 0V

2

Allocate the designations to the corresponding symbols in the table Magnetic Proximity Switch

Switch that closes when a solenoid is nearby Optical Proximity Switch

Inductive Proximity Switch

Switch closes when light barrier is interrupted

Changeover Switch (Limit Switch)

Switch that closes when induced electromagnetic field is changed Capacitive Proximity Switch

Change the line where current passes through to change the function of a certain circuit Switch that closes when its electrostatic field is changed

Designing the pneumatic and electrical circuit:

The actuation of a pushbutton (S1) will allow current to pass through and turn on the 1st magnetic proximity sensor which will turn on the first relay (R1). Once R1 is on, it will turn on the directional control valve (1M1) and make the cylinder extend. Once extended, it will activate the 2nd magnetic sensor, turning on R2 and 1M2 which will cause the cylinder to retract. It will continuously run until the normally closed switch (S2) is pressed to stop the circuit.

Equipment list: -

Double acting cylinder

-

Directional control valve, double piloted

-

Pushbutton, normally open

-

Pushbutton, normally closed

-

Changeover switch (3)

-

Magnetic proximity switch (2)

-

Relays (2)