Applications of Hydraulics&Pneumatics : Session 14

8/3/2019 Applications of Hydraulics&Pneumatics : Session 14

1/33

1

14pplications of

Hydraulic Pneumatics&By: Alireza Safikhani

Introduction

This module shows theThis module show s the

methods of application ofmethods of application of

pneumatic valves andpneumatic valves andcomponents for control andcomponen ts for control and

automationautomation

The methods of pureThe methods of pure

pneumatic sequentialpneumatic sequential

control are confined tocontrol are confined to

simple examplessimple examples

The majority of modernThe majority of modern

systems are control ledsystems are controlled

electronically and is theelectronically and is the

subject of electrosubject of electro --

pneumatic modulespneumatic modules

A m essage to pneumaticA m essage to pneumatic

circuit designers:circuit designers:

Use proven and rel iableUse proven and rel iabledesign techniquesdesign techniques

Produ ce circuits andProduce circuits and

documentation that aredocumentation that are

clear to readclear to read

Design for safetyDesign for safety

Do not try to be tooDo not try to be too

clever, the circuit will beclever, the circuit will be

difficult for others todifficult for others toread and maintainread and maintain

Symbols

The standard for fluid power symb ols is ISO 1219The standard for fluid power symb ols is ISO 1219--1. This is a1. This is a

set of basic shapes and rules for the construction of fluidset of basic shapes and rules for the construction of fluid

power symbolspower symbols

Cylinders can be drawn to show their extreme orCylinders can be drawn to show their extreme orintermediate positions of stroke and any length above theirintermediate positions of stroke and any length above their

widthwidth

Valves show all states in the one symbol. The prevailing st ateValves show all states in the one symbol. The prevailing stat e

is shown w ith the port connectionsis shown w ith the port connections

Other components are single state symbolsOther components are single state symbols

Symbols single acting actuators

Single acting, sprungSingle acting, sprung

instrokedinstroked


outstrokedoutstroked Single acting, sprungSingle acting, sprung

instrokedinstroked, magnetic, magnetic


outstrokedoutstroked, magnetic, magnetic


2/33

Symbols double acting actuators

Double acting, nonDouble acting, non--

cushionedcushioned

Double acting, adjustableDouble acting, adjustablecushionscushions

Double acting, through rod,Double acting, through rod,

adjustable cushionsadjustable cushions

Double acting, magnetic,Double acting, magnetic,

adjustable cushionsadjustable cushions

Double acting,Double acting, rodlessrodless ,,

magnetic, adjustablemagnetic, adjustable

cushionscushions

Symbols rotary actuators

SemiSemi --rotary double actingrotary double acting

Rotary motor singleRotary motor single

direction of rotationdirection of rotation

Rotary motor biRotary motor bi --directionaldirectional

Symbols valves

2/ 22/ 2Valve push button /Valve push button /

springspring

3/ 2 Valve push button /3/ 2 Valve push button /

springspring

3/ 2 Valve3/ 2 Valve detenteddetented leverlever

operatedoperated

2

13

12 10

21012

1

1

2

312

10

Symbols valves

3/ 23/ 2Valve differentia lValve differential

pressure operatedpressure operated

5/ 2 Valve push button /5/ 2 Valve push button /

springspring

5/ 3 Valve double pressure5/ 3 Valve double pressure

operated spring centreoperated spring centre

1

24

5 3

14 12

1

24

5 3

1

2

3

12 10


3/33


4/33

Symbols operators manual

General manual

Push button

Pull button

Push/pull button

Lever

Pedal

Treadle

Rotary knob

Symbols operators mechanical

Plunger

Spring normallyas a return

Roller

Uni-direction orone way trip

Pressure

Pilot pressure

Differential pressure

Detent in 3 positions

Symbols 5/3 valves

All valves types shown in the normal position

Type 1. All ports blocked

Type 2. Outlets to exhaust

Type 3. Supply to outlets

Symbols function components

NonNon --return valvereturn valve

Flow regulatorFlow regulator uniun i --

directionaldirectional

Flow regulator biFlow regulator bi --directionaldirectional

Two pressureTwo pressureANDAND

Shuttle valveShuttle valveOROR

SilencerSilencer

Quick exhaust valve withQuick exhaust valve with

silencersilencer

Pressure to electric switchPressure to electric switch

adjustableadjustable

* Note: Traditional symbol inextensive use (preferred)

*

ISO 1219-1 Old


5/33

Symbols air line equipment

Water separator withWater separator with

automatic drainautomatic drain

Filter with manual drainFilter with manual drain

Filter with automatic drainFilter with automatic drain

Filter with automatic drainFilter with automatic drain

and service indicatorand service indicator

LubricatorLubricator

Pressure regulator withPressure regulator with

gaugegauge

F.R.L. filter, regulator ,F.R.L. filter, regulator ,

lubricator simplified symbollubricator simplified symbol

Circuit layout

The standard for circuitThe standard for circuit

diagrams is ISO 1219diagrams is ISO 1219--22

A4 format or A3 folded toA4 format or A3 folded toA4 height for inclusion in aA4 height for inclusion in a

manual with other A4manual with other A4

documentationdocumentation

To be on several sheets ifTo be on several sheets if

necessary w ith l inenecessary w ith l ine

identification codeidentification code

Minimum crossing l inesMinimum crossing l ines

Limit valves position ofLimit valves position ofoperation by actuatorsoperation by actuators

shown by a marker withshown by a marker with

reference code to symbolreference code to symbol

Circuits should be drawnwith all actuators at the topof the page in order ofsequential operation

Other components to bedrawn in sequential orderfrom the bottom up and fromleft to right

Circuit should show thesystem with pressure

applied and ready to start

Component identification

The ISO suggestedThe ISO suggested

component numberingcomponent numbering

system is suited for largesystem is suited for large

circuits and those draw n oncircuits and those draw n on

several pagesseveral pages

For this presentation aFor this presentation a

simple code is usedsimple code is used

For cylinder s: A,B,C etc.For cylinde rs: A,B,C etc.

For associated feedbackFor associated feedback

valves: alphavalves: alpha--numeric codenumeric code

a0a0 for proof offor proof ofinstrokeinstroke,,

a1a1 for proof of outstrokefor proof of outstroke

For cylinder B: b0 and b1For cyl inder B: b0 and b1

A

a0 a1

1

2

3

12 10

a0

2

13

12 10

a1

Note: the a0 valve symbol isNote: the a0 valve symbol is

drawn in the operateddrawn in the operated

position because theposition because the

actuator A isactuator A is

instrokedinstroked

Example circuit

Run/End

Aa0 a1

Bb0 b1

Cc0 c1

a0 a1 b0b1 c0c1

10 bar max 6 barTo all inlet ports marked

SequenceRun/EndA+B+B-C+C-A-Repeat


6/33

Actuator control 2/2 valve

2/2 Valve actuator control

A pair of the most ba sic ofA pair of the most basic of

al l valve types the 2/ 2 canall valve types the 2/2 can

be used to control a singlebe used to control a singleacting cyl inderacting cylinder

The normally closedThe normally closed

position of the valve isposition of the valve is

produced by the springproduced by the spring

The operated position isThe operated position is

produced by the pushproduced by the push

buttonbutton

One valve admits air theOne valve admits air the

other valve exhausts itother valve exhausts it

21012

1

11012

2OUT IN


The button marked OUT isThe button mark ed OUT is

pushed to operate the valvepushed to operate the valve

Air is connected to theAir is connected to the

cylinder and itcylinder and it outstrokesoutstrokes Air cannot escape toAir cannot escape to

atmosphere through theatmosphere through the

valve marked I N as this isvalve marked I N as this is

closedclosed

The air at atmosphericThe air at atmospheric

pressure in the front of thepressure in the front of the

cylinder vents through thecylinder vents through the

breather portbreather port

210

1

1211012

2OUT IN


The push button of theThe push button of the

valve marked OUT isvalve marked OUT is

released and it returns to areleased and it returns to a

normal closed positionnormal closed position

Air is now trapped in theAir is now trapped in the

system and provided theresystem and provided there

are no leaks the piston rodare no leaks the piston rod

wil l stay in thewil l stay in the outstrokedoutstroked

positionposition

If the load increases beyondIf the load increases beyond

the force exerted by the airthe force exerted by the air

the piston rod wil l start tothe piston rod wil l start to

move inmove in

210

1

1211012

2OUT IN


7/33


The button marked IN isThe button marked IN is

pushed to operate the valvepushed to operate the valve

Air escapes and the pistonAir escapes and the pistonrod moves to therod moves to the instrokedinstroked

positionposition

The push button must beThe push button must be

held operated unti l theheld operated unti l the

piston rod is fully inpiston rod is fully in

Atmospheric air w il l beAtmospheric air w il l be

drawn in to the front of thedrawn in to the front of the

cylinder through the ventcyl inder through the vent

portport

210

1

121

2

1012

OUT IN


If the button marked IN isIf the button marked IN is

released the piston rod wil lreleased the piston rod wil l

remain in theremain in the instrokedinstrokedpositionposition

Any leaks in the installationAny leaks in the installation

can cause the piston rod tocan cause the piston rod to

creepcreep2

10

1

121

2

1012

OUT IN


To control the speed of theTo control the speed of the

piston rod, flow restrict orspiston rod, flow restr ictors

are placed in the pipesare placed in the pipes closeclose

to each of the valves.to each of the valves.

Adjustment of theAdjustment of the

restrictors wil l slow dow nrestrictors wil l slow dow n

the flow rate thereby givingthe flow rate thereby giving

independent outstroke andindependent outstroke and

instrokeinstroke speed controlspeed control1012 1012

OUT IN

2

1

1

2


By repeated operation ofBy repeated operation of

either button duringeither button during

movement the piston rodmovement the piston rod

can be moved in sm all stepscan be moved in small steps

for approximate positioningfor approximate positioning

This will only be successfulThis will only be successful

under slow speedsunder slow speeds

1012 1012

OUT IN

2

1

1

2


8/33


With any compressed airWith any compressed air

system that intentionallysystem that intentionally

traps air, the potentialtraps air, the potentialhazard of this must behazard of this must be

recognisedrecognised

Unintended release orUnintended release or

application of pressure canapplication of pressure can

give rise to unexpectedgive rise to unexpected

movement of the piston rodmovement of the piston rod

A pressure indicator orA pressure indicator or

gauge must be fitted togauge must be fitted to

warn of the presence ofwarn of the presence ofpressurepressure

210

1

121

2

1012

OUT IN


3/2 valve actuator control

A 3 port valve provides theA 3 port valve provides the

inlet and exhaust path andinlet and exhaust path and

is the normal choice for theis the normal choice for the

control of a single actingcontrol of a single acting

cylindercylinder

In the normal positionIn the norm al position

produced by the spring, theproduced by the spring, the

valve is closedvalve is closed

In the operated positionIn the operated position


button the valve is openbutton the valve is open


held down for as long as theheld down for as long as thecylinder iscylinder is outstrokedoutstroked

1

2

3

12 10




is the normal choice for theis the normal choice for the

control of a single actingcontrol of a single acting

cylindercylinder

In the norm al positionIn the normal position

produced by the spring, theproduced by the sprin g, the






held down for as long as theheld down for as long as thecylinder iscylinder is outstrokedoutstroked

1

2

3

12 10


9/33




is the normal choice for theis the normal choice for thecontrol of a single actingcontrol of a single acting

cylindercylinder








held down for as long as theheld down for as long as the

cylinder iscylinder is outstrokedoutstroked

1

2

3

12 10


To generally slow theTo generally slow the

cylinder speed ancylinder speed an

adjustableadjustablebibi--directional flow regulatordirectional flow regulator

or fixed restrictor can beor fixed restrictor can be

usedused

The flow regulator settingThe flow regulator setting

wil l be a compromise as thewil l be a compromise as the

ideal outstroke speed mayideal outstroke speed may

not produce the desirednot produce the desired

results for theresults for the instrokeinstroke

speedspeed

1

2

3

12 10


To control the outstrokeTo control the outstroke

speed of a single actingspeed of a single acting

cylinder without control lingcylinder without control l ing

thethe instrokeinstroke speed, aspeed, a un iuni --

directional flow regulator isdirectional flow regulator is

usedused

The flow into the cyl inderThe flow into the cylinder

closes the non return valvecloses the non return valve

and can only pass throughand can only pass through

the adjustable restrictorthe adjustable restrictor

By adjusting the restrictorBy adjusting the restrictor

the outstroke speed of thethe outstroke speed of the

cylinder can be setcylinder can be set

1

2

3

12 10


For independent speedFor independent speed

control in each directioncontrol in each direction

tw o flow regulators aretwo flow regulators are

requiredrequired

Instal led in oppositeInstal led in opposite

directions to each otherdirections to each other

Upper regulator controlsUpper regulator controls

the outstroke speedthe outstroke speed

Lower regulator controlsLower regulator controls

thethe instrokinginstroking speedspeed1

2

3

12 10


10/33




is the normal choice for theis the normal choice for thecontrol of a single actingcontrol of a single acting

cylindercylinder








held down for as long as theheld down for as long as the

cylinder iscylinder is outstrokedoutstroked

1

2

3

12 10



For a double acting cylinderFor a double acting cyl inder

the power and exhaustthe power and exhaust

paths are switchedpaths are switched

simultaneouslysimultaneously

When the button is pushedWhen the button is pushed

the supply at port 1 isthe supply at port 1 is

connected to port 4 and theconnected to port 4 and the

outlet port 2 connected tooutlet port 2 connected to

exhau st port 3. The cylinderexhau st port 3. The cylinder

moves plusmoves plus

When the button is releasedWhen the button is released

port 1 is connected to port 2port 1 is connected to port 2

and port 4 connected toand port 4 connected toport 5. Cylinder minusport 5. Cylinder minus

1

24

5 3

14 12

+-


For a double acting cyl inderFor a double acting cylinder

the power and exhaustthe power and exhaust

paths are switchedpaths are switched

simultaneouslysimultaneously

When the button is pushedWhen the button is pushed

the supply at port 1 isthe supply at port 1 is

connected to port 4 and theconnected to port 4 and the

outlet port 2 connected tooutlet port 2 connected to

exhau st port 3. The cylinderexhaust port 3. The cylinder

moves plusmoves plus

When the button is releasedWhen the button is released

port 1 is connected to port 2port 1 is connected to port 2

and port 4 connected toand port 4 connected toport 5. Cylinder minusport 5. Cylinder minus

1

24

5 3

14 12

+-


11/33


Independent speed controlIndependent speed control

of the plus and minusof the plus and minus

movementsmovements In m ost applications speedIn m ost applications speed

is controlled by restrictingis controlled by restricting

air out of a cylinderair out of a cylinder

Full power is developed toFull power is developed to

drive the piston with speeddrive the piston with speed

control led by restricting thecontrol led by restricting the

back pressureback pressure

1

24

5 3

14 12

+-


Independent speed controlIndependent speed control

of the plus and minusof the plus and minus

movementsmovements In m ost applications speedIn m ost applications speed

is controlled by restrictingis controlled by restricting

air out of a cylinderair out of a cylinder

Full power is developed toFull power is developed to

drive the piston with speeddrive the piston with speed

control led by restricting thecontrolled by restricting the

back pressureback pressure

1

24

5 3

14 12

+-


Valves with a spring returnValves with a spring return

are monoare mono--stable and needstable and need

the operator to be held al lthe operator to be held al l

the time that t he cyl inder isthe time that the cyl inder is

required in the plus positionrequired in the plus position

BiBi --stable valves wil l stay instable valves wil l stay in

the position they were lastthe position they were last

se tse t

The lever valve exampleThe lever valve example

illustrated indicates aillustrated indicates a

detent mechanism. Thedetent mechanism. The

lever need not be held oncelever need not be held once

the new position has beenthe new position has beenestablishedestablished

1

24

5 3

14 12

+-

Manual control

Remote m anual control of aRemote m anual control of a

double acting cyl inderdouble acting cyl inder

Valve marked + wil l causeValve marked + wil l cause

the cyl inder to outstroke orthe cyl inder to outstroke ormove plusmove plus

Valve mark edValve mark ed -- wil l causewil l cause

the cyl inder tothe cyl inder to instrokeinstroke oror

move minusmove minus

The 5/2 double pi lot valveThe 5/2 double pi lot valve

is biis bi--stable therefore thestable therefore the

push button valves onlypush button valves only

need to be pulsedneed to be pulsed

1

24

5 3

14 12

1

2

3

12 10

1

2

3

12 10

+ -

+-


12/33


13/33

Semi-automatic control

Manual remote start of aManual remote start of a

double acting cyl inder withdouble acting cyl inder with

automatic returnautomatic return Cylinder identified asCylinder identified asAA

Trip valve operated at theTrip valve operated at the

completion of the pluscompletion of the plus

stroke identified asstroke identified asa1a11

24

5 3

14 12

1

2

3

12 10

1

2

3

12 10

+ -

+-

A

a1

a1

Fully-automatic control

Continuous automaticContinuous automatic

cycl ing from roller operatedcycl ing from roller operated

trip valvestrip valves Manual Run and End of theManual Run and End of the

automatic cycl ingautomatic cycl ing

Cylinder wil l come to rest inCylinder wil l come to rest in

thethe instrokedinstroked positionposition

regardless of when theregardless of when the

valve is put to Endvalve is put to End

Tags for the roller feedbackTags for the roller feedback

valves a0 and a1 show theirvalves a0 and a1 show their

relative positionsrelative positions

1

24

5 3

14 12

2

13

12 10

1

2

3

12 10

1

2

312

10

Run/End

+-

A

a0 a1

a0 a1

Sequential control

Circuit building blocks

These circuits can be considered as building blocks for largerThese circuits can be considered as building block s for larger

sequential circuits consisting of tw o or m ore cyl inderssequential circuits consisting of tw o or m ore cyl inders

Each actuator wil l have a pow er valve and tw o associatedEach actuator w il l have a power v alve and tw o associated

feedback va lves. The first actuator to move also hasfeedback valv es. The first actuator to move also has

a Run/ End valvea Run/ End valve

Run/End

A B

a0 a1 b0 b1


14/33

Repeat pattern sequence

A repeat patt ern sequenceA repeat patt ern sequence

is one where the order ofis one where the order of

the movements in t he firstthe movem ents in the firsthalf of the sequence ishalf of the sequence is

repeated in the second halfrepeated in the second half

Each actuator may have oneEach actuator may have one

Out and In stroke only inOut and In stroke only in

the sequencethe sequence

There may be any numberThere may be any number

of actuators in the sequenceof actuators in the sequence

The signal starting the firstThe signal starting the first

movement must passmovement must pass

through the Run/End valvethrough the Run/End valve Needs only the basicNeeds only the basic

building blocks to solvebuilding blocks to solve

Examples of repeat patternExamples of repeat pattern

sequences:sequences:

A+ B+ C+ D+ AA+ B+ C+ D+ A-- BB -- CC-- DD--

AA-- B+ CB+ C --A+ BA+ B -- C+C+

C+ A+ BC+ A+ B -- CC--AA-- B+B+


The two cyl inders A and B are to perform a simple repeatThe two cyl inders A and B are to perform a simple repeat

pattern sequence as fol lows: A+ B+ Apattern sequence as fol lows: A+ B+ A-- BB --

Apply the ruleApply the rule The signal given by the completion of eachThe signal given by the complet ion of eachmovement w il l initiate the next movem entmovement w il l initiate the next movem ent

In this w ay the rol ler valves can beIn this w ay the rol ler valves can be

identified and labelledidentified and labelled

Run/End

A B

a0a1b0 b1

a0 a1 b0 b1


For three cylinders A, B and C also to perform a simp le repeatFor three cyl inders A, B and C also to perform a simple repeat

pattern sequence as fol lows: A+ B+ C+ Apattern sequence as fol lows: A+ B+ C+ A-- BB -- CC--

Apply the ruleApply the rule The signal given by the complet ion of eachThe signal given by the complet ion of each

movement w il l initiate the next movem entmovement w il l initiate the next movem ent

Run/End

A

c0 c1

a0 a1

B

a0a1

b0 b1

C

b0b1

c0 c1

Non-repeat pattern sequence

If the rule applied to a repeat pattern sequence is applied toIf the rule applied t o a repeat pattern sequence is applied to

any other sequence there w il l be opposed signals on one orany other sequence there wil l be opposed signals on one or

more of the 5/ 2 valves preventing operationmore of the 5/ 2 valves preventing operation

This circuit demonstra tes the problemThis circuit demonst rates the problem

The sequence is A+ B+ BThe sequence is A+ B+ B--AA--

Run/End

A B

b1a1a0 b0

a0 a1 b0 b1


15/33


16/33

Cascade (two group)

A B

a1

b0

a0 a1 b0 b1

Run/End

a0 b1

Sequence

Gp l A+ B+ Gp ll B- A-

Gp l

Gpll

Cascade (two group)

A B

a1

b0

a0 a1 b0 b1

Run/End

a0 b1

Sequence


Gp l

Gpll

Cascade (two group)

A B

b0

a0 a1 b0 b1

Run/End

a1

a0 b1

SequenceGp l A+ B+ Gp ll B- A-

Gp l

Gpll

Cascade (two group)

A B

b0

a0 a1 b0 b1

Run/End

a1

a0 b1

SequenceGp l A+ B+ Gp ll B- A-

Gp l

Gpll


17/33

Cascade (two group)

A B

a0 a1 b0 b1

Run/End

a1

a0

Sequence


Gp l

Gpll

b0

b1

Cascade (two group)

A B

a0 a1 b0 b1

Run/End

Sequence


Gp l

Gpll

b0

b1

a1

a0

Cascade building blocks

A tw o group building blockA tw o group building block

consists of a lever valve toconsists of a lever valve to

run and end t he sequencerun and end t he sequence

plus the 5/ 2 double pi lotplus the 5/ 2 double pi lot

operated cascade valveoperated cascade valve

For a tw o group systemFor a two group system

consisting of any num ber ofconsisting of any num ber of

cylinders this building blockcylinders this building block

and the cyl inder buildingand the cyl inder building

blocks are al l that isblocks are al l that is

required to solve therequired to solve the

sequencesequence

1

24

5 3

14 12

1

2

312

10

Gp l

Gp ll

Sel l

Sel llRun/End

Cascade building blocks

Gp l

Gp ll

Sel l

Sel ll

Gp lll

Sel lll

Run/End

This three groupThis three group

building blockbuilding block

establishes anestablishes an

interconnectinginterconnecting

pattern that canpattern that canbe extended tobe extended to

any number ofany number of

groupsgroups


18/33


19/33


20/33


The valve illustrated hasThe valve illustrated hasallall

ports blockedports blocked in the midin the mid

positionposition Whenever the m id positionWhenever the m id position

is selected the pressureis selected the pressure

conditions in the cylinderconditions in the cylinder

wil l be frozenwil l be frozen

This can be used to stop theThis can be used to stop the

piston at part stroke inpiston at part stroke in

some positioningsome positioning

applicationsapplications

Flow regulators mountedFlow regulators mountedclose to the cylinder toclose to the cylinder to

minimise creepminimise creep

24

15 314 12


This version of a 5/ 3 valveThis version of a 5/ 3 valve

isis centre open exhaustcentre open exhaust

The supply at port 1 isThe supply at port 1 isisolated and the cyl inderisolated and the cyl inder

has power exhausted whenhas power exhausted when

this centre position isthis centre position is

selectedselected

The version illustratedThe version illustrated

shows a monoshows a mono--stablestable

version double pilotversion double pilot

operated spring centreoperated spring centre

The cylinder will be preThe cylinder will be pre --exhausted when changingexhausted when changing

from the mid positionfrom the m id position

24

15 3

14 12


This version of a 5/ 3 valveThis version of a 5/ 3 valve

isis centre open pressurecentre open pressure

The supply at port 1 isThe supply at port 1 is

connected to both sides ofconnected to both sides of

the cyl inder and thethe cyl inder and the

exhaust ports isolated whenexhaust ports isolated when

this centre position isthis centre position is

selectedselected

Can be used to balanceCan be used to b alance

pressures in positioningpressures in positioning

applicationsapplications

The version illustrated isThe version illustrated is

monomono--stable, doublestable, doublesolenoid, spring centresolenoid, spring centre

1

24

5 3

14 12

Logic functions for poppet and

spool valves


21/33


22/33

Logic AND

To obtain the output Z bothTo obtain the output Z both

plungers X AND Y must beplungers X AND Y must be

operated and heldoperated and held If X only is operated the airIf X only is operated the air

wil l be blocked at port 1 inwil l be blocked at port 1 in

valve Yvalve Y

If Y only is operated thereIf Y only is operated there

wil l be no pressurewil l be no pressure

available at port 1available at port 1

If either X or Y is releasedIf either X or Y is released

the output signal Z wil l bethe output signal Z wil l be

lostlost

1

2

3

1

2

3X

Y

Z

12 10

12 10

Logic AND



operated and heldoperated and held If X only is operated the airIf X only is operated the air


valve Yvalve Y






lostlost

1

2

3

1

2

3

12 10

X

Y

Z

12 10

Logic AND



operated and heldoperated and held

If X only is operated the airIf X only is operated the air


valve Yvalve Y






lostlost

1

2

3

12 10

1

2

3

12 10

X

Y

Z

Logic AND

This methodThis method must notmust not bebe

used as a two handedused as a two handed

safety controlsafety control

It is too ea sy to abuse. e.g.It is too easy t o abuse. e.g.

one of the buttons could beone of the buttons could be

permanently fixed downpermanently fixed down

and the system operatedand the system operated

from the other button onlyfrom the other button only

Use the purpose designedUse the purpose designed

tw o handed safety controltwo handed safety control

unitunit

1

2

3

12 10

1

2

3

12 10

X

Y

Z


23/33

Logic OR

Use of anUse of anORORfunctionfunction

shuttle valveshuttle valve

Source X and Y can beSource X and Y can beremote from each other andremote from each other and

remote from the destinationremote from the destination

of Zof Z

When X or Y is operated theWhen X or Y is operated the

shuttle valve seal movesshuttle valve seal moves

across to prevent the signalacross to prevent the signal

Z from being lost throughZ from being lost through

the exhaust of the otherthe exhaust of the other

valvevalve

X

Y

Z

1

2

3

12 10

1

2

3

12 10

Logic OR





of Zof Z






valvevalve

X

Y

Z

1

2

3

12 10

1

2

3

12 10

Logic OR



Source X and Y can beSource X and Y can be

remote from each other andremote from each other and

remote from the destinationremote from the destinationof Zof Z






valvevalveX

Y

Z

1

2

3

12 10

1

2

3

12 10

Logic OR



Source X and Y can beSource X and Y can be

remote from each other andremote from each other and

remote from the destinationremote from the destinationof Zof Z






valvevalveX

Y

Z

1

2

3

12 10

1

2

3

12 10

L i OR L i NOT


24/33

Logic OR





of Zof Z






valvevalve

X

Y

Z

1

2

3

12 10

1

2

3

12 10

Logic NOT

A logic NOT applies to theA logic NOT applies to the

state of the output whenstate of the output when

the operating signal isthe operating signal is

present (the output ispresent (the output is

simply an inversion of thesimply an inversion of the

operating signal)operating signal)

The valve shown is aThe valve shown is a

normally open type (inletnormally open type (inlet

port numbered 1)port numbered 1)

When the signal X isWhen the signal X is

present ther e is NOT outputpresent there is NOT output

ZZ When X is removed output ZWhen X is removed output Z

is givenis given

2

31

12 10

Z

X

Logic NOT





simply an inversion of thesimply an inversion of theoperating signal)operating signal)





present ther e is NOT outputpresent ther e is NOT output

ZZ

When X is removed output ZWhen X is removed output Zis givenis given

2

31

12 10

Z

X

Logic NOT





simply an inversion of thesimply an inversion of theoperating signal)operating signal)





present ther e is NOT outputpresent there is NOT output

ZZ

When X is removed output ZWhen X is removed output Zis givenis given

2

31

12 10

Z

X

L i MEMORY L i MEMORY


25/33

Logic MEMORY

A logic MEMORY allows theA logic MEMORY allows the

output signal state (ON oroutput signal state (ON or

OFF) to be maintained afterOFF) to be maintained after

the input signal has beenthe input signal has been

removedremoved

Any biAny bi --stable valve is a logicstable valve is a logic

MEMORYMEMORY

With this leverWith this lever detenteddetented

valve, once the lever hasvalve, once the lever has

been moved X direction or Ybeen moved X direction or Y

direction it can be releaseddirection it can be released

and wil l stay in thatand wil l stay in thatpositionposition

Z

X

1310

Y12

Logic MEMORY

A logic MEMORY allows theA logic MEMORY allows the

output signal state (ON oroutput signal state (ON or

OFF) to be maintained afterOFF) to be maintained after

the signal that set it hasthe signal that set it has

been removedbeen removed Z

X

13

12 10 Y

Logic MEMORY

A biA bi --stable double pi lotstable double pi lot

valve can be set or resetvalve can be set or reset

simply by a pulse (push andsimply by a pulse (push and

release) on buttons X or Yrelease) on buttons X or Y

Z

13

X

Y1

2

3

12 10

1

2

3

12 10

12 10

Logic MEMORY

A biA bi --stable double pi lotstable double pilot




Z

13

X

Y1

2

3

12 10

1

2

3

12 10

12 10

Lo i MEMORY Lo i MEMORY


26/33

Logic MEMORY





Z

13

X

Y1

2

3

12 10

1

2

3

12 10

12 10

Logic MEMORY

A biA bi --stable double pi lotstable double pilot




Z

13

X

Y1

2

3

12 10

1

2

3

12 10

12 10

Logic MEMORY





Z

13

X

Y1

2

3

12 10

1

2

3

12 10

12 10

Logic MEMORY (latch)

A popular m emory circuit isA popular memory circuit is

the latchthe latch

Will not reWil l not re--make aftermake after

pneumatic power fai lurepneumatic power fai lure

A pulse on X operates theA pulse on X operat es the

pilot / spring valve to givepilot / spring valve to give

output Zoutput Z

A feedback from Z runsA feedback from Z runs

through the normally openthrough the normally open

valve Y to latch thevalve Y to latch the

operation of Z when X isoperation of Z when X is

releasedreleased

A pulse on Y breaks theA pulse on Y breaks thelatch and Z is exhaustedlatch and Z is exhausted

X

Y

Z

13

1

2

3

12 10

1012

3

2

1

1210


27/33

Logic circuits (spool valves)


28/33

Logic arrangements for fullybalanced spool valves

Logic circuits (spool valves)

Selection / Diversion

Latch OR, AND, NOT

Single pulse maker

Slow pressure build

Pre-select

Single pulse control

Air conservation Double flow

Counting

5/2 OR

Click the section to advance directly to it

NO / NC

3/2 NO / NC

A fully balanced valveA fully balanced valve

allows pressure on any potal lows pressure on any pot

or combination of portsor combination of ports

A single valve can be usedA single valve can be used

normally open or normallynormally open or normallyclosedclosed

For normally open theFor normally open the

supply pressure issupply pressure is

connected to port 1connected to port 1

For normally closed theFor normally closed the



1

2

3

12 10

2

13

12 10

3/2 NO / NC

A fully balanced valveA fully balanced va lve

allows pressure on any potal lows pressure on any pot

or combination of portsor combination of ports

A single valve can be usedA single valve can be used

normally open or normallynormally open or normallyclosedclosed

For normally open theFor normally open the



For normally closed theFor normally closed the



1

2

3

12 10

2

13

12 10

diversion

diversion


29/33

diversion

Selection of one of tw oSelection of one of tw o

supplies connected to portssupplies connected to ports

1 and 3 can be different1 and 3 can be different

pressurespressures

Diversion of one supply toDiversion of one supply to

one of two outletsone of two outlets

If it is required to exhaustIf it is required to exhaust

the downstream air a 5/ 2the downstream air a 5/ 2

valve is requiredvalve is required

1

2

3

12 10

2

13

12 10

diversion

Selection of one of tw oSelection of one of tw o

supplies connected to portssupplies connected to ports

1 and 3 can be different1 and 3 can be different

pressurespressures

Diversion of one supply toDiversion of one supply to

one of two outletsone of two outlets

If it is required to exhaustIf it is required to exhaust

the downstream air a 5/ 2the downstream air a 5/ 2

valve is requiredvalve is required

1

2

3

2

13

12 10

12 10

Latch with controls

In this version of a latch theIn this version of a latch the

push button valves arepush button valves are

connected to performconnected to performOROR

andandNOTNOT functionsfunctions

TheTheOFFOFFvalve must bevalve must beplaced last in the signalplaced last in the signal

chain so that if both valveschain so that if both valves

are operated together theare operated together the

OFFOFFcommand wi l lcommand wi l l

dominate over thedominate over theONON

commandcommand

1

2

3

12 10

2

13

12 10

2

13

12 10

ON

OFF

Out

OR, AND, NOT

A single 3/ 2 pi lot operatedA single 3/ 2 pi lot operated

spring return valve can bespring return valve can be

use for any of these logicuse for any of these logic

functionsfunctions

xxOROR yygives outputgives output zz

xxANDAND yygives outputgives output zz

xxgives NOTgives NOT zz

1

2

3

12 10

1

2

3

12 10

1

2

3

12 10

AND

OR

NOT

x y

z

x y

z

x

z

Single pulse maker

up


30/33

Single pulse maker

Converts a prolonged signalConverts a prolonged signal

xxinto a single pulseinto a single pulse zz

Signal z must be removedSignal z must be removedto al low the v alve to resetto al low the valve to reset

then x can be applied againthen x can be applied again

The duration of the pulseThe duration of the pulse

can be adjusted with thecan be adjusted with the

flow regulatorflow regulator

1

2

3

12 10

x

z

up

Choose a 3/2 pi lot springChoose a 3/2 pi lot spring

valve with a relatively highvalve with a relatively high

operatin g force e.g. 3 to 4operating for ce e.g. 3 to 4

barbar

When the quick connectWhen the quick connect

coupling is made, thecoupling is made, the

output at port 2 isoutput at port 2 is

control led at the rate of thecontrol led at the rate of the

flow regulator settingflow regulator setting

When the pressure is highWhen the pressure is high

enough to operate the valveenough to operate the valve

ful l flow wil l take overful l flow w il l take over

1

2

3

12 10

Pre-select

The lever valve can preThe lever valve can pre --

select the movement of theselect the movement of the

cylinder OUT or INcylinder OUT or IN

The movement w il l occurThe movement w il l occur

the next time the plungerthe next time the plungervalve is operatedvalve is operated

The plunger valve can beThe plunger valve can be

released immediately andreleased immediately and

subsequently operated andsubsequently operated and

released any number ofreleased any number of

t imestimes

1

2

3

12 10

1

2

3

12 10

1

2

312

10

OUT/INpre-select

5/2 OR function

The valve at positionThe valve at positionaa isis

reversed connected andreversed connected and

supplied from the valvesupplied from the valve

conventionally connected atconventionally connected at

positionposition bb The cylinder can beThe cylinder can be

control led from eithercontrol led from either

positionposition aa ORORpositionposition bb

1

24

5 3

1412

1

24

5 3

1412

a

b

Single pulse control Air conservation


31/33

Single pulse control

24

1412

1

2

3

12 10

15

12 10

1

2

3

2

13

1210

Each time the footEach time the foot

operated valve isoperated valve is

pressed the cyl inderpressed the cyl inder

wil l single stroke +wil l single stroke +

andand -- alternatelyalternately

First foot operationFirst foot operation

the cyl inder moves outthe cyl inder moves out

Second foot operationSecond foot operation

the cyl inder moves inthe cyl inder moves in

ThirdThird .. out and so on.. out and so on

Air conservation

Pow er stroke in thePower stroke in the instrokeinstroke

direction onlydirection only

Differential area of theDifferential area of thepiston gives an outstrokepiston gives an outstroke

force when the pressure isforce when the pressure is

balancedbalanced

Air used to outstroke isAir used to outstroke is

equivalent to a cyl inderequivalent to a cyl inder

with only the same bore aswith only the same bore as

the rod diameterthe rod diameter

Assumes the cylinder is notAssumes the cylinder is not

loaded on the plus strokeloaded on the plus strokeand low frictionand low friction

24

15

1412

Air conservation

Pow er stroke in thePow er stroke in the instrokeinstroke

direction onlydirection only

Differential area of theDifferential area of the

piston gives an outstrokepiston gives an outstroke

force when the pressure isforce when the pressure isbalancedbalanced

Air used to outstroke isAir used to outstroke is

equivalent to a cyl inderequivalent to a cyl inder

with only the same bore aswith only the same bore as

the rod diameterthe rod diameter

Assumes the cylinder is notAssumes the cylinder is not

loaded on the plus strokeloaded on the plus stroke

and low frictionand low friction

24

15

14

12

Double flow

Where a larger 3/ 2 valve isWhere a larger 3/2 v alve is

not availablenot available

Two flow paths in a 5/ 2Two flow paths in a 5/2

valve each with a separatevalve each with a separate

supply can be arranged tosupply can be arranged togive double flow or supplygive double flow or supply

separate devicesseparate devices

Ensure the tube size to theEnsure the tube size to the

cylinder is large enough tocylinder is large enough to

take the double flowtake the double flow

4 2

1 3

1214

5 1

Double flow Counting


32/33

Double flow

Where a larger 3/ 2 valve isWhere a larger 3/ 2 valve is

not availablenot available

Two flow paths in a 5/ 2Two flow paths in a 5/ 2

valve each with a separatevalve each with a separate

supply can be arranged tosupply can be arranged to

give double flow or supplygive double flow or supply

separate devicesseparate devices

Ensure the tube size to theEnsure the tube size to the

cylinder is large enough tocylinder is large enough to

take the double flowtake the double flow

4 2

1 3

1214

5

Counting

Counting applications areCounting applications are

best achieved with electrobest achieved with electro --

mechanical ormechanical or

programmable electronicprogrammable electronic

counterscounters

Pneumatic counting circuitsPneumatic counting circuits

use large numbers of logicuse large numbers of logic

valves and can be slowvalves and can be slow

The counting chain shownThe counting chain show n

wil l count to 4wil l count to 4

Red and blue are nonRed and blue are non --

overlapping alternateoverlapping alternatepulses, purple is the resetpulses, purple is the reset

lineline

1

2

3

4

Counting application

The counting circuit isThe counting circuit is

applied to count 4 strokesapplied to count 4 strokes

of a cylinderof a cylinder

At rest all counting valvesAt rest all counting valves

are held reset by the startare held reset by the startvalvevalve

StartStart outstrokesoutstrokesAA

Alternate signals fromAlternate signals from a1a1

andanda0a0 progressesprogresses

operation of the countingoperation of the counting

valves up the chainvalves up the chain

On the 4th operation ofOn the 4th operation ofa1a1

the green signal resets thethe green signal resets thestart valve to stop thestart valve to stop the

cylindercylinder

A

a0a1

a0 a1

Start

Feedback methods

Time delay Time delay


33/33

m d ay

A signal is restricted to slowA signal is restricted to slow

the rate of pressure buildthe rate of pressure build

up on a pressure switchup on a pressure switch

(3/ 2 differential pressure(3/ 2 differential pressureoperated valve)operated valve)

When the pressure switchWhen the pressure switch

operates a strong unoperates a strong un--

restricted output is givenrestricted output is given

A reservoir provide sA reservoir provides

capacitance to al low lesscapacitance to al low less

fine and sensitive settingsfine and sensitive settings

on the flow regulatoron the flow regulatormaking it easy to adjustmaking it easy to adjust

1

2

3

12 10

Signalin

Output

m d ay


double acting cyl inder withdouble acting cyl inder with

a time delay in thea time delay in the

outstrokedoutstroked position beforeposition beforeautomatic returnautomatic return

2

1

24

5 3

14 12

13

12 10

+-

A

a1

1

2

3

12 10

a1

1

2

3

12 10

Pressure decay


double acting cyl inderdouble acting cyl inder

Uses a low pressureUses a low pressure

operated valve connectedoperated valve connected

normally opennormally open When the back pressure inWhen the back pressure in

the front of the cyl inderthe front of the cyl inder

fal ls below 0.1 bar thefal ls below 0.1 bar the

return signal is givenreturn signal is given

Connection taken betw eenConnection taken betw een

the cyl inder and flowthe cyl inder and flow

regulatorregulator

Useful for pressing workUseful for pressing workpieces of variable sizepieces of variable size

1

24

5 3

14 12

2

13

12 10

+-

A

a1

21210

1 3 0.1bar

Electro-pneumatic

The majority of systems useThe majority of systems use

electrical/ electronic controlelectrical/ electronic control

due to the high degree ofdue to the high degree of

sophistication and flexibi l itysophistication and flexibility

Solenoid valves are used toSolenoid valves are used tocontrol cylinderscontrol cylinders

Feedback signals are fromFeedback signals are from

reed sw itches, sensors andreed sw itches, sensors and

electrical l imit switcheselectrical l imit switches

Logic is hard wired orLogic is hard wired or

programmed in to a PLCprogrammed in to a PLC

(programmable logic(programmable logic

controller)controller) a0 a1

1

24

5 3

14 12

A

a0 a1

Circuit building block foreach cylinder

Applications of Hydraulics&Pneumatics : Session 14

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Transcript of Applications of Hydraulics&Pneumatics : Session 14