Laboratory EPN

Electro-Pneumatics Laboratory 203

ELECTRO-PNEUMATICSELECTRO-PNEUMATICS LABORATORY EXPERIMENTSLABORATORY EXPERIMENTS



GENERAL INSTRUCTIONSAND SAFETY PRECAUTIONS

The arrangement of the equipment on the workstation should be as shown in the evaluated electro-pneumatic circuit diagram sketch.

The working pressure of pe=5 bar shall be at the pressure regulator of the air service unit.

The pneumatic components are to be firmly connected with plastic tubes and accessories according to the circuit diagram.

Also observe the proper removal of the connections of the hoses and other accessories from the components.

The working voltage for the electrical wiring diagrams shall be provided 24V DC power supply unit and an electric manifold unit.

The electrical components are to be firmly connected with jumper wires and accessories according to the circuit diagram

Handle the components with care and caution.

Arrange the components and other equipment after use.

Be guided accordingly with your subject instructor.

DRIVE ELEMENT

ACTUATING ELEMENT

Cylinder

Directional Control Valve

Air Compressor

Electric Motor

Y1

SIGNALING

ELEMENTPush-button

Relay Contact

Relay CoilSolenoid

CONTROL

ELEMENT

24V

0V

L1

N

S1 K1

Y1K1


ELECTRO-PNEUMATIC CONTROL CHAIN

ENERGY GROUP Pneumatic and electrical energies are

required in electro-pneumatic controls. Signal elements, control elements and

actuating elements are supplied with electrical energy.

Actuating elements and drive elements are supplied with pneumatic energy.

SIGNAL ELEMENTS The signaling elements convert manual

commands and mechanical motions into electrical signals.

CONTROL ELEMENTS The control elements connect the

approaching signals and direct these to the components of the actuating element group.

ACTUATING ELEMENTS The actuating elements take over the

function of connecting or converting electrical energy and pneumatic energy

DRIVE ELEMENTS The drive elements convert the pneumatic

energy into mechanical energy and motions.

REPRESENTATION OF PNEUMATIC CIRCUIT DIAGRAMS

Pneumatic Diagram

Electrical Wiring Diagram


EXPERIMENT 1

COMMAND-VARIABLE CONTROL OF CYLINDERS WITH SINGLE -SOLENOID VALVES

Objective

This experiment provides basic know-how and skills on the proper design, set-up and operation of electro-pneumatic controls using the direct and indirect control of a single-acting cylinder as an example.

List of Components and Equipment

Qty. Description

1 Pneumatic power supply

1 Air service unit (filter with water separator, pressure regulator and pressure gauge) with 3/2 directional control ball valve

1 Pneumatic Distributor, 6-fold

1 24VDC power supply unit

1 Electric Manifold unit

1 Control switch-2 pushbutton unit

1 Single-acting cylinder

1 Double-acting cylinder

1 3/2 directional control valve, electrically operated, spring return, closed neutral position

1 5/2 directional control valve, electrically operated, spring return, closed neutral position

1 Relay units, 4 changeover contacts

Pneumatic and Electrical Accessories

Problem Definition 1

1. Upon pressing a normally-open key-operated pushbutton switch, the solenoid coil of a directional valve shall be directly energized by this electrical switch causing the cylinder rod of a single-acting cylinder to move outward to its maximum extended position.

2. The piston rod of the single-acting cylinder should remain extended as long as the button is pressed.

3. Upon releasing the said electrical switch, solenoid coil of that directional valve will cause the piston rod of the single-acting cylinder to retract and return to its rear-end position.


4. Upon pressing a normally-open key-operated pushbutton switch, the coil of an electro-mechanical relay shall be energized by this electrical switch causing the electrical contact of this relay to indirectly energize the solenoid coil of a directional valve which then causes the cylinder rod of a double-acting cylinder to move outward to its maximum extended position.

5. The piston rod of the double -acting cylinder should remain extended as long as the button is pressed.

6. Upon releasing the said electrical switch, the coil of the electro-mechanical relay shall relieved of its electrical signal, which then causes the electrically-controlled directional valve to be relieved of its pilot energy which then causes the cylinder rod of a double-


acting cylinder to retract and return to its rear-end position

Procedure

1. Sketch the pneumatic circuit diagram based on the stated problem definition.

2. Sketch the electrical circuit diagram based on the stated problem definition.

3. Have your instructor check your circuit diagram for proper evaluation.

4. Gather the required components and arranged them properly on the workstation and in accordance with the verified electro-pneumatic circuit diagram.

5. Connect the pneumatic components with plastic tubes and accessories according to the circuit diagram.

6. Connect the electrical components with jumper wires and accessories according to the circuit diagram.

7. Make sure that the air service unit switch is in the off position and double check the connections of the hoses and other accessories if they are firmly coupled to the components for safe operation.

8. Turn on the pneumatic power supply (compressor) compressed-air distributor.

9. Turn on the switch the air service unit and set the working pressure of pe=5 bar at the pressure regulator.

10. Turn on the 24DCV power supply distributor.

11. The experiment is started and the proper function is verified.

12. Return and arrange the components and other equipment properly upon completion of the experiment.

13. Draw the pneumatic circuit diagram on the data sheet. State your observations and conclusion.


EXPERIMENT 1DATA SHEET

COMMAND-VARIABLE CONTROL OF CYLINDERS WITH SINGLE -SOLENOID VALVES

Pneumatic Circuit Diagram





Observation and Conclusion

EXPERIMENT 2

HOLDING-ELEMENT CONTROL OF A DOUBLE-ACTING CYLINDER WITH AN


IMPULSE VALVE, DIRECTLY CONTROLLED

Objective

This experiment demonstrates the control of a double-acting cylinder with an electrically controlled 5/2 directional control impulse valve without the use of a relay.


Qty. Description








1 5/2 directional control valve, electrically operated both ways


Problem Definition

1. Upon momentarily pressing a normally-open key-operated pushbutton switch, the solenoid coil of a directional valve shall be directly energized by this electrical switch causing the cylinder rod of a double-acting cylinder to move outward to its maximum extended position.

2. The piston rod of the double -acting cylinder should remain extended even after the pushbutton is released.

3. Upon momentarily pressing another normally-open key-operated pushbutton switch, the opposite solenoid coil of the directional valve shall be directly energized by this second electrical switch causing the cylinder rod of a double-acting cylinder to retract and return to its rear-end position.

4. The piston rod of the double -acting cylinder should remain retracted even after the latter pushbutton is released.

5. Hence, each pushbutton switch has its own unique function of either extending or retracting the cylinder only.

Procedure







7. Make sure that the air service unit switch is in the off position and double check


the connections of the hoses and other accessories if they are firmly coupled to the components for safe operation.









HOLDING-ELEMENT CONTROL OF A DOUBLE-ACTING CYLINDER WITH AN IMPULSE VALVE, DIRECTLY CONTROLLED





EXPERIMENT 3

STOPPING CONTROL OF A DOUBLE-ACTING CYLINDER WITH A 5/3


DIRECTIONAL CONTROL VALVE WITH A CLOSED MID-POSITION, INDIRECTLY CONTROLLED

Objective

The aim of this experiment is to demonstrate the most often applied solution for stop control in electro-pneumatics. A 5/3 directional control valve with a closed mid-position is used as an actuator.


Qty. Description




2 One-way Flow Control Valve





1 5/3 directional control valve, electrically operated, closed mid position, spring centered

2 Relay units4 changeover contacts


Problem Definition

1. Upon pressing a normally-open key-operated pushbutton switch, the coil of an electro-mechanical relay shall be energized by this electrical switch causing the electrical contact of this relay to indirectly energize the solenoid coil of a directional valve which then causes the cylinder rod of a double-acting cylinder to slowly move outward to its maximum extended position such that the length of its forward stroke is dependent upon the duration of the pressing of the pushbutton.

2. Upon pressing another normally-open key-operated pushbutton switch, the coil of another electro-mechanical relay shall be energized by this second electrical switch causing the electrical contact of this relay to indirectly energize the opposite control-solenoid coil of the same directional valve which then causes the cylinder rod to slowly move inward to its maximum retracted position such that the length of its backward stroke is also dependent upon the duration of the pressing of that pushbutton.

3. The piston rod of the double -acting cylinder should remain in whatever position it has reached when either of the two pushbuttons is released or not being pressed.

4. Hence, each pushbutton switch has its own unique function of either extending or retracting the cylinder to a certain length of stroke only.

Procedure

















STOPPING CONTROL OF A DOUBLE-ACTING CYLINDER WITH A 5/3 DIRECTIONAL CONTROL VALVE WITH A CLOSED MID-POSITION, INDIRECTLY CONTROLLED





EXPERIMENT 4

LOGICAL CONTROL OF A DOUBLE-ACTING CYLINDER WITH A SINGLE--


SOLENOID VALVE AND A DOUBLE-SOLENOID VALVES,

Objective

The aim of this experiment is to convey the understanding for the logical “AND” and “OR” functions in relay technology.


Qty. Description








1 5/2 directional control valve, electrically operated, spring return,





1. Upon pressing neither of two key-operated pushbutton switches, the spring of a single-solenoid spring return valve shall cause the cylinder rod of a double-

acting cylinder to assume a retracted position.

2. Upon pressing either of the two normally-open key-operated pushbutton switches alone, the coil of its corresponding electro-mechanical relay shall be energized by the actuated electrical switch causing the electrical contact of that relay to indirectly energize the solenoid coil of a single-solenoid valve which then causes the cylinder rod of the double-acting cylinder to move outward to its maximum extended position. Upon releasing the chosen pushbutton, the cylinder rod will retract and return to its rear-end position.

3. Upon pressing both pushbutton switches (not necessarily being at the same time), the cylinder rod shall also assume a retracted position.


4. Upon pressing neither of two key-operated pushbutton switches, the double-solenoid valve shall cause the cylinder rod of a double-acting cylinder to assume a retracted position. Hence, the opposite solenoid should be initially energized by the proper relay contact arrangement.

5. Upon pressing either of the two normally-open key-operated pushbutton switches alone, the coil of its corresponding electro-mechanical relay shall be energized by the actuated electrical switch causing the electrical contact of that relay to indirectly energize the solenoid coil of a double-solenoid valve which then causes the cylinder rod of the double-acting cylinder to move outward to its maximum extended position. Note that when the solenoid is energized, the initially energized opposite solenoid


should be de-energized at the same time. Upon releasing the chosen pushbutton, the cylinder rod will retract and return to its rear-end position.

6. Upon pressing both pushbutton switches (not necessarily being at the same time), the cylinder rod shall also assume a retracted position.

Procedure
















LOGICAL CONTROL OF A DOUBLE-ACTING CYLINDER WITH A SINGLE--SOLENOID VALVE AND A DOUBLE-SOLENOID VALVES,







EXPERIMENT 5


PRIORITY CONTROL OF A DOUBLE-ACTING CYLINDER WITH A SINGLE--SOLENOID VALVE, SPRING RETURN,

Objective

In this experiment, the most common priority control methods for actuating circuit systems are demonstrated as well as the various possible circuits with latching (storage circuits) using relay.


Qty. Description








2 5/2 directional control valve, electrically operated, spring return,



Problem Definition

1. Initially, upon momentarily pressing a key-operated pushbutton switch, the coil of an electro-mechanical relay shall be energized by this electrical switch causing the electrical contact of this

relay to indirectly energize the solenoid coil of a directional valve causing the cylinder rod of a double-acting cylinder to move outward to its maximum extended position and stay extended.

2. Upon momentarily pressing another key-operated pushbutton switch, the coil of another electro-mechanical relay shall be energized by this electrical switch causing the electrical contact of this relay to indirectly energize the solenoid coil of another directional valve causing the cylinder rod of another double-acting cylinder to move outward to its maximum extended position and stay extended. Note that the first cylinder will now move to its maximum retracted position and stay retracted the same time the second cylinder will extend.

3. Upon momentarily pressing the first pushbutton switch again, the coil of the first electro-mechanical relay shall be energized again by this electrical switch causing the electrical contact of this relay to indirectly energize the solenoid coil of the first directional valve causing the cylinder rod of the first double-acting cylinder to move outward to its maximum extended position and stay extended. Note that the second cylinder will now move to its maximum retracted position and stay retracted the same time the first cylinder will extend.

4. Hence, whichever pushbutton switch is actuated at any time shall cause its own controlled cylinder to extend and stay extended the same time making the other cylinder to retract and stay retracted.

5. However, upon momentarily pressing a third key-operated pushbutton switch, the cylinder rod of any of the two cylinders that is extended at any time shall be retracted and stay retracted.

Procedure

















PRIORITY CONTROL OF A DOUBLE-ACTING CYLINDER WITH A SINGLE--SOLENOID VALVE, SPRING RETURN,





EXPERIMENT 6


TIMER CONTROL OF A DOUBLE-ACTING CYLINDER WITH A DOUBLE--SOLENOID VALVE

Objective

This experiment shows the use of an electric, switch-on timer relay element in a hold element control.


Qty. Description









2 Relay unit, 4 changeover contacts

2 Timer Relay units


Problem Definition

1. Upon momentarily pressing a key-operated pushbutton switch, a pre-determined time shall elapse after which will energize a double-solenoid valve shall cause an initially retracted cylinder

rod of a double-acting cylinder to move outward to its maximum extended position and stay extended. (Note that being a double-solenoid valve, the opposite solenoid should be initially energized to ensure that the cylinder rod is also initially retracted).

2. By the same time that the cylinder had extended, another pre-determined time should elapsed after which will cause the cylinder rod to automatically retract and return to its rear-end position and stay retracted.

3. Note that only electro-mechanical relays and their corresponding contacts are to be used for the circuit and that roller limit switches and cylinder switches are not allowed for this problem.

Procedure







7. Make sure that the air service unit switch is in the off position and double check the connections of the hoses and other


accessories if they are firmly coupled to the components for safe operation.









TIMER CONTROL OF A DOUBLE-ACTING CYLINDER WITH A DOUBLE--SOLENOID VALVE





EXPERIMENT 7

POSITION -DEPENDENT SEQUENTIAL CONTROL OF A DOUBLE-


ACTING CYLINDER USING A DOUBLE--SOLENOID VALVE

Objective

This experiment intends to facilitate the understanding of reciprocation controls of a lone cylinder and provides practical knowledge of setting up a simple reciprocating control system.


Qty. Description










2 Roller limit switch or cylinder switch


Problem Definition

1. Upon momentarily pressing a key-operated pushbutton switch, a double-solenoid valve shall cause the cylinder rod of a double-acting cylinder to immediately to move outward to its

maximum extended position. (Note that being a double-solenoid valve, the opposite solenoid should be initially energized to ensure that the cylinder rod is also initially retracted). Upon reaching its maximum outward stroke, the cylinder rod will automatically retract and return to its rear-end position.

2. Upon reaching its initial position, the cylinder rod will again automatically extend and retract repeatedly until another key-operated pushbutton switch is momentarily pressed at any time to bring it to a complete stop but finishing the last sequence and returning the cylinder rod in its initial position.

3. Hence, closed-loop sequence of A+ A- using roller limit switches or cylinder switches.

Procedure







7. Make sure that the air service unit switch is in the off position and double check


the connections of the hoses and other accessories if they are firmly coupled to the components for safe operation.









POSITION-DEPENDENT SEQUENTIAL CONTROL OF A DOUBLE-ACTING CYLINDER USING A DOUBLE--SOLENOID VALVE





EXPERIMENT 8

POSITION-DEPENDENT SEQUENTIAL CONTROL OF TWO DOUBLE-ACTING


CYLINDER USING DOUBLE--SOLENOID VALVES

Objective

This experiment intends to facilitate the understanding of sequential controls of two cylinders and provides practical knowledge of setting up a control system with two pneumatic drives. The actual design and practice in developing sequential diagram and pneumatic and electrical circuit diagram shall also be exercised.


Qty. Description











1 Electronic sensor unit


Problem Definition

1. Upon detecting an object, an electronic sensor shall energize a double-solenoid valve which will cause the cylinder rod of a double-acting cylinder (cylinder A) to immediately move outward to its maximum extended position. (Note that being double-solenoid valves, the opposite solenoids should be initially energized to ensure that the two cylinders rods are also initially retracted). Upon reaching its maximum outward stroke, another double-solenoid valve shall cause the cylinder rod of another double-acting cylinder (cylinder B) to automatically move outward to its maximum extended position.

2. Upon reaching cylinder B’s maximum outward stroke, cylinder A will automatically retract and return to its rear-end position. Note that during the retraction of cylinder A, cylinder B remains extended. Upon reaching cylinder A’s initial position, cylinder B will automatically retract and return to its rear-end position.

3. Upon reaching cylinder B’s initial position, the sequence of cylinder actions will then repeat continuously if the electronic sensors continuously detects the object, otherwise the sequence will automatically stop at B- finishing the last sequence and returning the cylinder rods in their initial positions.

4. (OPTIONAL) The initiation of the sequence can also optionally triggered by a key-operated switch and stopped by another key-operated switch.

5. Hence, open-loop / closed-loop sequence of A+ B+ A- B- using roller limit switches cylinder switches.

Procedure

















POSITION-DEPENDENT SEQUENTIAL CONTROL OF TWO DOUBLE-ACTING CYLINDER USING DOUBLE--SOLENOID VALVES





EXPERIMENT 9

TIME-BASED PROCESS CONTROL FOR POSITION-DEPENDENT


SEQUENTIAL CONTROL OF TWO DOUBLE-ACTING CYLINDER USING DOUBLE--SOLENOID VALVES

Objective

This experiment intends to facilitate the understanding of incorporating a timer control circuit on sequential controls based process of two cylinders and provides practical knowledge of setting up a control system with two pneumatic drives.


Qty. Description











1 Timer Relay Unit


Problem Definition

1. Upon momentarily pressing a key-operated pushbutton switch, a double-solenoid valve shall be energized which will cause the cylinder rod of a double-acting cylinder (cylinder A) to immediately move outward to its maximum extended position. (Note that being double-solenoid valves, the opposite solenoids should be initially energized to ensure that the two cylinders rods are also initially retracted). Upon reaching its maximum outward stroke, another double-solenoid valve shall cause the cylinder rod of another double-acting cylinder (cylinder B) to automatically move outward to its maximum extended position.


3. Upon reaching cylinder B’s initial position, the sequence of cylinder actions will then repeat continuously until a predetermined time has elapsed which will then automatically stop the sequential movements of the cylinders at B- finishing the last sequence and returning the cylinder rods in their initial positions.

4. Note that the sequence of cylinder movements can also be manually stopped at any instant without regards to the timer-based process control element when another key-operated pushbutton switch is momentarily pressed.

5. Hence, time-based closed-loop sequence of A+ B+ A- B- using roller limit switches cylinder switches.


Procedure
















TIME-BASED PROCESS CONTROL FOR POSITION-DEPENDENT SEQUENTIAL CONTROL OF TWO DOUBLE-ACTING CYLINDER USING DOUBLE--SOLENOID VALVES





EXPERIMENT 10

COUNTER-BASED PROCESS CONTROL FOR POSITION-DEPENDENT


SEQUENTIAL CONTROL OF TWO DOUBLE-ACTING CYLINDER USING DOUBLE--SOLENOID VALVES

Objective

This experiment intends to facilitate the understanding of incorporating a counter control circuit on sequential controls based process of two cylinders and provides practical knowledge of setting up a control system with two pneumatic drives.


Qty. Description











1 Counter Unit


Problem Definition

1. Upon momentarily pressing a key-operated pushbutton switch, a double-solenoid valve shall be energized which will cause the cylinder rod of a double-acting cylinder (cylinder A) to immediately move outward to its maximum extended position. (Note that being double-solenoid valves, the opposite solenoids should be initially energized to ensure that the two cylinders rods are also initially retracted). Upon reaching its maximum outward stroke, another double-solenoid valve shall cause the cylinder rod of another double-acting cylinder (cylinder B) to automatically move outward to its maximum extended position.


3. Upon reaching cylinder B’s initial position, the sequence of cylinder actions will then repeat continuously until a number of sequential movements has been completed based on a predetermined number of desired counts which will then automatically stop the sequential movements of the cylinders at B- finishing the last sequence and returning the cylinder rods in their initial positions.

4. Note that the sequence of cylinder movements can also be manually stopped at any instant without regards to the counter-based process control element when another key-operated pushbutton switch is momentarily pressed.


5. Hence, counter-based closed-loop sequence of A+ B+ A- B- using roller limit switches cylinder switches.

Procedure
















COUNTER-BASED PROCESS CONTROL FOR POSITION-DEPENDENT SEQUENTIAL CONTROL OF TWO DOUBLE-ACTING CYLINDER USING DOUBLE--SOLENOID VALVES





Documents

Laboratory EPN