Chapter 07 - Pneumatic Logic Sensors and Actuators

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Chapter 6 Pneumatic Logic Sensors and Actuators

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t e r 6 : P e n u m a t i c l o g i c

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a n d a c t u a t o r s -

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Introduction to Pneumatic/!draulic s!stems

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• A h!draulic #control$ s!stem is commonl! used %orhea&! dut! and hea&! load' e(g( hea&! transportation&ehicles(

• A pneumatic #control$ s!stem has a lo)er responsetime #i(e( it is *uic+er$ than a h!draulic s!stem(

• A pneumatic control s!stem is %re*uentl! used in,uilding automatic assem,l! machines due to its

lo)er cost compared to h!draulic or electric s!stems(

• An electric s!stem is controlled ,! &oltage #$ andcurrent #Amp$(

• In a pneumatic/h!draulic s!stem' pressure #,ar$ ise*ui&alent to &oltage and .o) #l/min$ is e*ui&alent to



6(1 Pneumatic limit' push-,utton and emergenc! stop &al&es

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• he main structure o% a limit &al&e' apush ,utton and an emergenc! stop&al&e is the same(

•Pneumatic limit &al&es are e*ui&alentto mechanical limit s)itches in their%unction(

•Similarl!' pneumatic push ,utton andemergenc! stop &al&es are e*ui&alentto mechanical push ,utton andemergenc! stop s)itches in their%unctions(

• he main di0erence ,et)een thepneumatic limit &al&es and themechanical s)itches' in the latter' theactuating arm or plunger shi%ts a so-called directional-control &al&e ratherthan electric contacts(

•

Same thing is applied %or push ,uttonand emergenc! &al&es(

LimitValve

Push buttonvalve

Push buttonswitch



6(1 Pneumatic limit' push-,utton and emergenc! stop &al&es

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3/2 limit valve (meaning 3 connections and 2 positionsvalve).

he &al&e is sho)n as normall! closed' so that the outlet line ise2hausted to atmosphere )hen the &al&e is not actuated(

hen the &al&e is actuated' the roller is pressed against thereturn spring at the ,ottom' so that the &al&e opens and passessuppl! pressure to the outlet line(

Illustration: http://geea(org(pagesperso-orange(%r/P4E5/distri,3"(s)%

http://geea.org.pagesperso-orange.fr/PNEUM/distrib_3_2.swf






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4ormall! closed limit&al&e: source is closed

#not connected tooutput$

4ormall! open limit&al&e: source is open#connected to output$



A Simple Pneumatic 4et)or+: Single Acting C!linder Actuation 4et)or+

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A9 Push ;utton

http://educ!pedia(+aradimo&(in%o/li,rar!/&al%3nc(s)%

A9A-

http://educypedia.karadimov.info/library/valf3nc.swf






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5/2 limit valve (meaning 5 connections and 2positions valve):

• here are " independent outlet lines' one is normall! openand the second is normall! closed(•<or ,oth cases' the limit &al&e can ,e used as push-,utton&al&e and do the same stated %unctions(

Illustration :http://geea.org.pagespersoorange.!r/P"#$%/distrib&5&2.sw!







6( Pneumatic directional control &al&e s!m,ols

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Illustration: 8/3 &al&e

http://-







6(" Pneumatic directional pilot control &al&e

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Pneumaticdirectional pilot

control valve

• ost directional-control&al&es are o% the spooland slee&e t!pe •

A 8/" pilot &al&e:

•hen the spool positionor pilot line is pressuri?ed,! p1 line' .o) passes,et)een A @ ports' and

; @ E ports' )hile C is,loc+ed(

•I% pilot line p" ispressuri?ed' the spoolshi%ted to the li%t )ith

corresponding change in.o) paths as illustrated

ne mat c rect ona



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neumat c rect onasolenoid control valve

• he main di0erence ,et)eenthe solenoid actuationdirectional control &al&e andpilot control &al&e' is the )a!o% displacement o% the &al&espool(

• In the case o% a pilot control

&al&e' spool &al&edisplacement is carried outusing t)o pressuri?ed air p1and p"

• In the case o% a solenoid

actuation directional &al&e #orsimpl! solenoid directional&al&e$' a solenoid and springmechanisms are used todisplace the spool &al&e

•

Similarl!' solenoid actuationcan also ,e used )ith 3/"



6( Additional Pneumatic S!m,ols

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6(8 Simple Pneumatic 4et)or+s: A4 %unction



6(8 Simple Pneumatic 4et)or+s:

ou,le Acting C!linder 4et)or+ using a Pilot line &al&e

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achine se*uence : START, A+, A-



Pro,lems

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Pro,lems

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Pro,lems

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Chapter 07 - Pneumatic Logic Sensors and Actuators

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