Note: Descriptions are shown in the official language in which they were submitted.
PROPORTI~L AIR VALVE AND MEIHCD
OF PR(~VIDING PROPOE~TIC~L AIR El~
}~CK~D OF ~E INV~rrIC~7
Ihis inventicn re~ates to a p ~ ortional air valve ~nd re
particularly to a ~ethod of achi~ving proportional air flowO
Althouyh pneumatic and hydraulic contr~ls are in~erchangeably
~sed in many types of applications, the absence of an effective, and
~elatively lcw cos~ prcportional valve for pneumatic systems has limited
~he applic~tion of pneumatics. Ihat is, mDst pneumatic valves are of the
on~off type and, there~ore, do not provide a propDrti~nal output that
p~rmits their utilization in devices such as in~ustrial mbots or ~he like~
~lthough p m portio~ality may be a~hieved ~h m ugh ~he use of vari~ble
~egulat~s or ~he like, such d~ices are very ~xpensive and thus ~imi~ ~he
~pplication of pneu~atics ~here pr~portional oD~x~l i5 ~Eedo
It is, there~ore, a principal object of ~his in~ention to pr~vide
~ed meth!~d for ~ a p~e~na~ic valve in a proportio~al
1}~,
It is another object of t~e ~ nti~n to prcv~de a low cost,
prDp~rti~nall~ operabl~ pneuma~i~ valve.
~UMW~RY OF T~E INVENTI~N
A first eature of ~e inNention is adapte~ tD be emkvdied in a
~ethcd of achieving pr~portional oontr~l of a p~umatic ~al~re that includes
a ~low ~ontr~l element t~t is ~upp~rted for mcvement between a closed
position~ an intermEdiate p~sition wherein restricted flcw is permitte~ and
a fully cpened position where.Ln ~ibs~antially unrestricted flow is
tted~ The method ccmpxises the steps of applying a substantiall~
consta~t actua~ing ~rce ~or ~ovLng the flow control el~ment r~m its
closed position ~oward i~s qpened pDsitionO The actuating ~orce is applied
~eguentially ~or predetermi~ed ~me in~ervals wi~h intervening ~ime
inter~als w~exein no actuating force is applied. A relatively low rate
~iasin~ force is exerted on the flow contxr-l element ~or urginq the flow
contr~l element continuously towRrd its closed positionO In addition, a
subst ntially higher rate biasing force is exerted upon the flcw contrvl
element ~or resisting further mcvement of t~ flcw control element when the
flow cDntrol element has ~Dved a predetermined amcunt fncm its clos~d
position toward its ~ully opened positionO
Another feature of the invention is adapted to be embodied in a
proportionAl, pneumatic flow control valv~. Such a vzlve comprises a
housing that defines an inlet port and a supply port. A flow control
~lement is mDvable ~r3m a clo~ed pvsition wherein camnunic~tion between the
ports is substantially precluded ~nd an op~ned position ~hereLn
substantially u~restricted ~ cation ~etween ~he parts is permitt~o
F~rst biasing means are provided ~or ~onstan~ly urging the flow ~ontr~l
elem~nt ~cward its clo&ed position and second biasing means are provided
for resisting navement of the flow oontrDl element toward its fully opened
positio~ when ~he flow oontrDl element moves a predetermi~ed c ~ t fxom
its closed position toward its ~ully opene~ position. T~e second bias ~g
~ns has a substantially higher rate ~han the firs* biasing means.
ERIEF DESCRIPTIUN oF THE DR~ING
The single figure d the dra ~ g is an axial crDss-sectional view
taken ~hrough a spool ~ype pneumatic vzlve oonstructed in accordance with
an embodiment of the invention and adapted to ~e operated in accordcanoe
with a methcd of th~ inventionO
In the drawi~g, a proportional pneumatic valve ~ons~xucted and
oFerated in acaondance wi~l an embodiment of ~he m vention i8 identi~ied
generally by the reference numeral 11, ~he valve 11 con~ist~ of an outer
-- 2
3~
housiDg, indicated generally by ~he reference numeral 12, which oomprises a
nain bo~h~ F~lt 13 and end closuYes 14 and 15, ~hat are secured to the main
b&dy pY~rt 13 in anv known manner. m e main body part 13 is provided with
thr~ugh bore 1~ ~hat is intersected ~y a plural;ty of p~rts 17~ 18, 19, 21
and 22. qhe ~orts 17 ~hrDugh 22 terminate in respective ~nnular ca~ities
23, 24, 2~, 26 and 27 that extend around ~he bore 160
~ sleeve ~8 is pDsitioned in ~he bore ~6 an~ is shDrter in length
th~n ~he ~ore. Ihe sleeve 28 is axially positioned by means of a pair of
spaCer5 29 ~nd 31 and ~ ers 32 and 33 that are positioned at the
respec~i~e ends of the sleeve 28 and which are axially fixed by the end
caps 1~ ~nd lS. The sleeve 28 i~ also pr~vided with a plurality of
circun~rential grcoves 34 in whi~h O rings 35 are re~eived so as to
prDvid~ a seal bet~en the sleeve 28 a~d the ~ body 13 80 that the p~rts
7t 1~ 19, ~1 and ~2 are is~lated ~rçm each other.
~ l~h~u~h any of a wide variety of porting arrangemen~s may be
employ ~ with ~he ~alve bcdy and valve sleeve arrangement describedJ in ~he
illustGated en~cdinent the port 19 co~prises an inlet port that is adapt~d
to be ~ cated wqth a source of hi~h pressure air (not shcwn~. The
ports ~ and ~ e supp~y p~rts which ma~, in a ~ypical application,
extend ~ ~pposite ends of a double acting pneumatic cyl ~ er (~ot ~ho~n~.
The p~rk~ 17 and 22 are exhaust pDrts an~ may be opened to the abmosFhere
~ither directl~ or ~hrough any suitable exhaustLng system. The valve
sleeve 28 is pnDvided with a p~uxality of ~hrough passages 36~ 37, 38, 39
and 41 ~hat ~ t ccmmunica~ion between the annulæ valve body cavities
23, 24, 2~ 26 ~n~ 27, res ~ vely, and an internal hore 42 of the sleeve
28.
~ A ~l~w controllincJ sFoDl~ m dicated generally by the reference
numeral 43~ i~ slid~bly supported within the bore 42 of ~he valve sleeve
28. I~ th~ illustrate~ embodhment and wi~h ~he p~rting arrangement
de~cribed, ~h~ vzlve ~poDl 43 inclucles a central land 44, and a p~ir of end
3 ~
lands 45 and 46. ~ reduced di~me~er area 47 is provided between the lands
44 an~ 45 and a simll~r r~duced diameter area is prGvided between ~he lands
44 and 46. The lands 45 and 46 are provided with circumferential bal~ncing
recesses 49.
In its neutral or closed p~siti~n, as shGwn in ~he figure, the
land 44 closes communisation of the port 38 with the bore 42 and ~he
reduced diam,eter sections 47 ana 48 ~ t ccmmunication between the
respective ports 36, 37 and 39~ 41. Thus, the associated pneumatic
cylinder has both of its ends opened to exhaus~ and this cylinder will be
held in a flxed position.
In acc~r~anoe with ~he i~vention, a særing ~rrangement is
provided ~or h~lding ~he valve sFoD1 43 in its neutral, d osed po~i~ion and
for providing an increasing resis~ance ~ m~vement of the vzlve spool 43 in
ei~her of its directions af~er a predet~rmined degree of m~vement fr~m the
closed position. miS centering spring arran ~ t includes a pair of
spring retainers 52, each of which is in ~ngagement ~ith a respective end
of t~e valve ~pcol 43. The spring retainers 52 are pr~vided with a bDre 53
in which one end of a relatively lcw rate centering sprin~ 54 is ne5tedO
l~e opposite ends of ea~h of ~he cen~ering springs 54 are received in
respective ~ores 55 formed in ~he ~nd d osures 14 and 150 qhe sprLngs 54
~e preloaaed and urye the valve spool 43, as not~d, to its closed
position. However, the ~pr ~ ~ 54 are relatively ~w sabe, as has been
noted, and any a~tuating force applied ~D the val~e ~pcol 43 will cause one
of the springs reta mers 52 to nove in an ~ al direction and co~press the
associa~ed spring 54.
A seco~dO substantially higher ra~e spring 56 is positioned at
ea~h end of the valve spool 43~ Ihe springs 56 are nested in ccunterbvres
57 of the ~pxLng retainers 52 and ~re adapbed to engage the re~pec*ive end
closures 14 and 150 The spri~gs 56 ~re slightly sh~rber in length than the
normal distance between the end closures 14 and 15 and the respe~tive ~nds
o~ ~he counterho~es 57 of the spring retainers 52 so that when the valve
sFool 43 is in its neutral or closed position, the springs 56 wqll ke
comple~ely unl~aded.
~ me~ls (not shawn) is prcvided for actuating the valve spool 43
ko mcve it in either ~ ion from its clos0d position. This ~ans may be
an actuator or any known type n~rmally employed wi~h such valves such as a
o sDlenoid wind ~ s ~hich may be seles*ively energized so as to draw
the spool ~3 in one or the other axial direction, depending upon which ooil
is enexgized. rn acoGrd2noe wath the inve~tion~ the proportional contr~l
is f ~ achieved by appl ~ g successive pulses of force to ~he spool 43
tend~ng ~o nove i~ in ~he desired direction. That is, ~he associated
solenoid windings ~re ~nergized fDr brief p~r~ods of time with inbervendng
mter~als of nonDenerization. The proportional cQntro~ may be achiev~d ~y
ither changing ~he freguency of ~he energi~ations ~rD alt~rnativel~ by
~creas~ng the duration of ~he period of time which ~he ~olenoids are
energizea.
I~ ~h~ solenoid associated with ~he land 45 is energi~ed, ~or
exa~ple, it will ~xert a ~orce ~ ng b~ draw ~h~ spoDl 43 b~ th~
f I c/~, t
Initial m~vement to ~he ~ is resifibed only by ~he very liyht ~entering
~pr ~ 54 and the spo31 43 will bend to nGve rapidly in ~his ~ ion SD
as tD tend to Gause ~he port 38 of the inlet 19 bv regisber wnth t~e recess
~80 ~ the s~ne blme, the c ~ cation of ~he exhaust port 36 with ~he
supply p~rt 37 will ~e increased~ Thus~ pressuriz~d air will flow frcn the
port 38 to ~he port 39 and one end of the associa~ed p~elnatic ~ylinder
w~ile the other end will be exhaus~ed. When this m~vement occurs, the
exhaust p~rt 41 wqll be closed by ~he land 46.
A~ter a predetermined degree of m~vementO determined by ~he
relative leng~h of the ~pring 56, the ~pring xetaLner 52 will en~age the
r 19~t
~pring 56 at ~he lcft hand emd of ~he ~pool ~3 and pr wide a ~ubstantially
increased force that ixsists fur~r openm g of the valve spool 43 in this
~;rection. This dual spriny arrangement coupled ~th the prcportional
actuation o thR spcol 43 has been foun~ to give a proportional air
pr~ssure outlet to the cylinder ~hat will pe~nit proportional actuation in
a m~nner not heretofore possible with such simple pneumatic valves~
It should be readily apparent that actuation of the spool 43 in
the op~osite direction so as to expose ~he supply port 37 ~o ~he inlet port
38 ana close ~he exhaust port 36 is done b~ energizLng the ~olenoid
associat~d with the land 46 in a ~anner as described in conjunction with
actuation in ~he opposite directionO
It should be readily apparent ~rom the ~ore~oing descrip~ion that
the described valve arrangement and its me~hcd of actuation permits hi~hly
effective proportional pneumatic contrDl at a relativel~ low CostD
Although the device has been described in conjunction with a spoDl type
valve, the same principle may be applied t3 po~pet valves or any other type
of pneumatie valvet ~or ~hat matter. Also, althou~h the arrangement is
disclosed in cDnjunction with two ~prings for resisting movement, it m~y
~1SD be used with a greater ~umber of sprLnys than tw~ or wi~h spr ~ s
hav m g non~ ra~es.
Al~hough an emtDdDm~nt of ~he inv~ntion has been illustrated and
described and ~ther embodiments described, still further ~hanges and
mcdifications may ~e made, wqthout depaxting ~r3n the spirit and soGpe of
the mv~ntion, as defined ~y ~he appended claimsO
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