CA1306447C - Fan adjustment for paint spray gun - Google Patents

Abstract

ABSTRACT OF THE INVENTION
A paint spray gun is provided with a means of adjustably controlling fanning of the spray which may be regulated independently of the rotative position of the air cap.
A valve member axially shiftable by an adjustment screw adjustably controls the flow of air to fanning control ports in the air cap without interfering with the flow of atomizing air to the paint spray nozzle.

Description

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Our lleference: CA~-115-A
~AN ADJUSTMENT FOI~ PAINT SP12AY ~UN
UACKGROUND OF THE INVENTION
. _ In conventional paint ~pray guna, a atream of paint under pre~ure i~ discharged from a relatively ~mall ori~ice in a nozzle while air under pre~sure is di~charged radially inw~rdly into the ~tream from an annular opening ~urrounding the nozzle clo~ely adjacent the paint di~charge orifice to ~tomize the ~tream o~ palnt into a spray o~ fine particle~. Tha epr~y thuo prodùced move0 aw~y from the gun in ~n exp~ndin~ conic~l p~ttern whoae apex ia ut the nozzle.
It i~ fre~uently desired to modify the circular cro~-section of the normal conical ~pray pattern by transforming thi~
pattern into one of a narrowed and elongated generally elliptically ~haped cros~-~ection ~o that the ~pray pattern more clo~ely re~emble~ that of a ~lat ~ided f~n.
In prior art ~pray gun~, ~anning o~ the ~pray p~ttern ia typically acco~pli~hed by providiDg on the ~ront of the air cap a pair of diametrically oppo~ed porta Dpaced radially outwardly from oppoeite side~ of the annular ~ir di~char¢~
opening and orie~ted to direct air jet~ toward oppoaite ~idee o~
the ~pray pattern at a loc~tion 0paced a short di~tance forw~rdly from the nozzle orifice. The~e jet~ have the ef~ect o~
flattening the ~ides of the conical ~pray pattern a~ain~t which they are directed. At any given di~tance ~rom the noz~le, this - 25 action trflnaform~ the normally circular cro~ ection o~ the conical spray into a generally elliptically ~haped cro~s-e~ction who~e major axis i~ somewha-t greater than the origin~l cone diameter and who~e minor axis i~ ~omewhat le~s th~n the ori~inal cone diameter. The "flatnes~" of the elliptical cro~s-6e¢tion will incre~se with an increase o~ the pre~ur0 ot which air i~
expelled fro~ the diametri~cally oppo~ed fanning port~.

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In prior art ~un~, ad ju~tlDent of -the fanning of th~
~pray i~ typically made by rotatively adju~ting th~ air cap.
This udjuat~ent exerts a valving aCtioD which s~tabli~hes m~ximum air flow when tl~e di~trically oppoued volve port~ li in eitller a vertical plan~ containing the nozzle sxi~ or Q horizontal pl~ne containing the nozzle axi~. The flow ~rom the fanning part~ i~
reduced aR the air c~p i~ rotated to become æ~ro when the f~nning ports ~re ~idway b~tween tha hori~ontal ~nd vcrticul po~ition~
referred to above~ When the fanning port0 are ~t thi~ midway position, the ~pray ~s~u~e~ it~ original conic~l ~orm.
While the foregoing ~rr~ngement provide~ for adjustment to th~ f~nning of the ~pray, thi~ sdju~tm~nt i~ dependent upon the rot~ted pO~itiOII of the air cup obout t}le nozzle ~xl~.
Adju~tm0nt of the Yan width (minor axi~ of thc olliptical ~Rn cro~ ection) to a width between ~aximum or un~odified conical 0prsy und minimum width require~ the ~ir cap to have its port~
located in a genersl plane inclined from the vertic~l. Thi~
incliDstion o~ the fanning port~ e~tabli~he~ the ~ngle th~ ~a~or QXi0 of the elliptical configur~tion will a~u~e with re~pect to the vertic~ itu~tion which io inconveniont to th~ opor~tor who would pr~fer that thi~ ~jor axi~ be either vertical or horizontal for sll de~r~e0 of fennin~.
The present invention i~ directsd to a ~pray ~un 1D
~hich f~nning may be adju~t~bly controlled completely 5 indspendently o-~ the rotative orientation o~ ~he eir c~p.
SUMMARY OF T~IE_INVENTION
In accordance with the pre~ent invention, a p~iDt 0prBy gun include~ a main hou~ing ~ro~ which a hollow tubular ~e~ber project~ forwardly. The p~int ~pr~y nozzle, of conventional con~truction, i~ threadably ~ounted at the forward end of thi~

tubular member who~e interior communicates with a ~itting in the h~u~ing to which a supply of p~int under pre~re i~ attached.

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A generally cylindricul hou~in~ exten~io~ mounted on the hou~ing in coaxiel ~urroundin~ relation~hip to th~ tubular me~ber an~l nn ~ir cup i~ threededly attached to the forward end of this tubular exten~i~n to dufin~ en internal ~nnulur air chamber within the exten~ion 3urroundin~ the tubular paint carrying mel~ber. The air cap is provided with a central air di~churge openiD~ through which air is di~ch~r~ed to ~tomize paint di~charged under pre~sure from the noz~le ori~ice into ~pruy.
The rearward or inner ~ide of the air cap i~ formed with ~ rearwardly opening counter bore which define~ a emooth continuation o~ the inner ~ide wall of the extension o~ the hou~in~. The counter bore in the air cap terminates at u radially inwardly projecting shoulder and passage~ extend through the air cap ~rom diametrically oppoYed inlets at the juncture o~
the ~houlder aDd counter bore to di~etrically oppo~ed fenning porta oriented to discharge air against oppo~ite ~ideo o~ the paint spray cone. A cylindrical valve member iA ~lidably received within the counter bore and provided with un annular radiel ~kirt ~t it~ forwerd end which, when ~eated aguin~t ~ho rudial shoulder on the air cap wlll ceal eh~ inlst opunin~ o~
the pa~sage~ in the eir cup which lead to the fannin~ port~. Tho ~kirt defines a central opening through the forward ~nct o~ the air cylinder which is of a diameter sub~tantially larger then the tubular hou~ing member ~o that air can puY~ ~t ~ll time~ from the interior of the cylindrical air cylinder to the central air disch~rge openin~ o~ the air cap. A portion of the wall of the cylinder iB provided with an opening BO that air can paB8 through o ~itting on the hou~inl~ into the interior o~ the hou~iag extension ~nd thence throueh the openirlg to the interior of thc air cylinder. The re~rw~rd end o~ the air cylinder i~ ~orm~d with an openin~ which i~ ~lid~bly receiv~d upon th~ tubular paint pa~aage member of the housing. A control rod i~ coupled to the resrward end of ttle ~ir cylinder and extend~ re~rwurdly to thJ
re~r end of th~ housing where it ia ~tt~hed to ~ ~anual ~dju~tment l;lember thread~bly r~ceived in the houaing. By threading the adju~tmsnt member iDto or out o~ the housing, the position of the r~dial akirt o~ the air cylinder ralative to the radi~l shoulder on the air cap ~ay be varied at will to p~rtially or fully open or cloae the inl~t~ to the air cap pu~a~ea leadin~
to the fanning port~.
Other objecta und features of the invention will become apparent by reference to the ~ollowing ~pecific~tion Qnd to the dr~wings.
IN TI~E DRAWINGS
Fig. 1 is ~ side view of ~ paint ~pr~y gun embodyiDg the preaent invention;
Fig. 2 is a d~tailed cros~-~ectional view tallan on a centr~l vertical pl~ne throu~h the forw~rd portion o~ the gun o~
Fig. l;
Fig. 3 i8 a detailed aide ~iew of the rearw~rd portion of tha gun of Fig. 1, with cert~in parts broken away or ~hown in ~ection;
~ ig. 4 i~ a per~pectivc view of the ~ir cylinder ~nd B
portion of the control rod of the gun o-f Fig. l; and Fig. 6 i~ a front view of the nozzle of the gun of Fig.
1.
~ efsrring firat to Figs. 1 and 2, a ~pray gun embDdyin~
the preaent invention includes a piatol-like main houfling designated generally 10 havin~ ~ generally cylindrical exten~ion 12 fixedly ~ecured to it~ ~orw~rd end. An ~ir CHp 14 i~ ~ixedly mounted on the front end of extension 12 a~ by an iDternally threaded ~nnular ring 16 formed at it~ forward end with e radially inwardly projecti~ng flsn~e 18 (Fig. 2) axially confined - ~ 3~

to the main body of the cap a~ by a C ring 20 re~iliently seuted within a circumferential notch 22. The ~kirt 16 iB freely rot~table relative to the main body of ~ir cap 14. A nozzle 24 project~ coMxially through a central opening 2~ (Fig. 2) in tho forward end of air cap 14~
Nozzle 24 is of conventional con~truction ~nd, a~ be~t seen in Fi~. 2, i~ formed witll a forwardly convargent tepered bore 2~ which ~er~in~te~ at an orifice 30 at the front ~nd of the nozæle. Noz~le 2~ is ~ormed with ~ threuded ~hank~3;2 which i~
threadably received within the forward end of a forwardly projecting hollow tubular member 34 integrally formed on m~in hou~ing 10. Paint under pre~ure iB Bupplied to the central pu~age 36 which extend~ through tubular ~e~ber 34 via a fittin~
38 threadably received within hou~ing lD ~nd huving ~ centr~l pa~sage 40 in communication with pe~a~e 36. Th~ rear or ri~ht hQnd end of pa~s~ge 36 as viewed in E'ig. 2 is clo4ed by ~
threaded plug 42 which al~o ~lidably support~ and guid~ ~n clon~te rod-like needle v~lve 44 h~vin~ a tapered forward e~d 46 ; which m~y be ~eated in the conical bore 28 o~ nozzl~ 24 to clo~e the orifice 30.
Referriilg now to Fig. 1, a trigger 47 i~ pivotally mounted upon housing 10 to eng~ge en enl~rged diameter portion 4B
for~ed on needle valve 44 to draw the valve to the right a~
viewod in Fig~. 1 and 2 when trig~ur ~7 i8 ~queezed. Rod ~4 extends resrwardly past the trigger and it~ enlarged dia~eter aection 48 continue~ throu~h hou~iDg 10 to be coupled to An adju~tment knob 50 threadsbly mounted within the hou~ing.
The couplin~ between needle vslve 44 ~nd adju~ting knob 50 i~ a 9pring loaded coupling of conventional construction which act~ to continuou~ly bias needle valve 44 to the left a0 viewed in Figs. 1 and ~ to it~ closed seated po~ition within nozzlc 24.

The adju~tm0nt knob 50 e~entially locQte~ the end li~it o~

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movement of the needle ~alve 44 to the right a~ viewed in Figs. 1 und 2 to e~tabli~h ~ ~llaximum opaning of noz~le 24 wh~ll trigg~r 47 i8 fully depre~ed. This arrangement for controlling the flow of paint under pr~sure from orifice 30 i~ conventionul.
Referring now particulhrly to Figs. 2 and 5, from Fig.
5 it i~ ~een thut nozzle 24 is formed with ~ plurality of radially projecting win~s 52 whose radially outer end~ lie on a cylindrlcal ~urface coaxial ~lth the axi~ o~ noz~le Z4. The re~rwurd ~ide of air cap 14 i~ formed with a counter bore 54 of a diameter such that the outer end~ of wings ~2 o~ tha nozzle ere slidably received within bore 54. ~t it~ inner end, counter bore 64 mer~eH with an inclined conical bore 56 which extsnds from counter bore 54 to pierce the front ~ide of ~ir cap 14 to est~bli~h o diecharge openin~ 26 surrounding ths forw~rd tip of nozzle 24. The inclin~tion of the wall of the coniccl bore 66 and the inclinution o~ the for~ard side of no~le 24 a~ at 58 ~nd the axial dimen~ions of the air cap and nozzle are such that an air pa~sage i8 provided, when the no2zle ~nd ~ir cap ~re ae~embled in the gun, between di~charge npenin~ 26 ~nd a cha~ber 60 constituted by an enl~rged diameter counter bore ut the rearward ~ide of air c~p 14. Thi~ paB~a~e ext~nd~ from openin~
26 through sp~ce between the oppoaed inclined ~ur~oc~ ~6 o~ the air c~p and 5B o~ the nozzle und thence throu~h the ~pace~
between adjacent wing~ ~2 o~ the nozzle.
Hou~ing exten~ion 12 i~ ~ormed with e bore 64 in it0 forwnrd end of the same dismeter a~ the mating counter bore 62 in ~ir cap 14, nnd bores 62 und 64 slidably receive the forwnrd end o~ a hollow cylindrical air cylinder 66. Air cylinder 66 iB
formed with a bore 68 in it~ forward end wnll 70 which i~ of a dinmeter larger thnn the outer diameter of tubul~r mcmber 34 o~
the ~ain hou~ing ~o thut chnmber 60 within nir cap 1~ i~ nlw~y~
in communicction with the ~ollow interior of air cylinder 66.

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Th~ interior of air oylinder 6~ is in turn in con~tant communication wi~h sn air chamber 72 formed within exten~ion 1~
via a cutout portion 74 in the air cylinder. Air under pre~ure may be supplied to chamber 72 vis a fitting 76 threaded into exten~ion 1~ ~nd hnving an air ~upply passage 78.
The rear wall 80 o~ cylinder 66 i~ formed with ~ bore 82 which slidably receive~ tubular member 34 of m~in hou~ing 10.
At the upper ~ide o~ cylinder 66 ear it~ rear wall, a T s31uped slot 84 is formed to receive the end of an uctuatin~ rod 86. A~ best ~ee in Fig. 4, ~lots 88 sre formed in oppoHite sides of the forward end of rod 86 ~o th~t when the end of tbe rod i~ ~eated in T ~lot 84, the rod and cylinder ere coupled to ench other for concurrent axi~l movement in either direction.
As be~t seen in Fig. 2, rod 86 extend~ rearw~rdly ~ro~
cylinder 66 throu~h a bore 90 in housin~ 10. Re~erring now to ~ig. 3, actu~ting rod 86 i~ formed with a reduced diemeter end section 92 at it~ rearward end which pas~ rearwardly through a bore 94 in an adju~tment ~crew 96. A knurled nut 98 thre~dably received on the end o-f portion 92 of UCtUatiDg rod 86 uxially ~ixe~ rod 86 to ~dju~tment ~crew 96 while ~ccommvdatin~ rotery movement u~ screw 96 relutive to rod a6. ~od 86 is re~trained B~in~t rotary movement by the enga~ement betwaen the ~lots 88 (Fig. 4) in the forward end of rod 86 and the wall~ o~ tbe T ~lot 84.
Adjustment ~crew 96 i~ threadably received a~ at 100 within a fitting 102 threadably locked to housing 10. Threading of adjustment screw 96 into or out of ~itting 102 iB tran~itted by actuatil)g rod 86 to alr cylinder 66 to axially shi~t air cylinder 66 relative to air cap 14.
neturning now to Fig. 2, Q pair o~ fnll control pa~ageB
104 are formed through air c~p 14 to extend from ch~mber 60 in the air cap to inwardly inclined uir di~charge port~ 106.

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In Fig. 2, ~ir cylinder 66 i~ shown ~t its maximum opened po~ition in which air under pres~ure flowin~ into chsmber 60 from fitting 76 c~n pa89 freely both to the centrsl opening 26 of air cap 14 to utomize ~ paint stream i~uing under pre~ure 5 fro~ nvzzle ~0 ~d ~l~o freely tllrou~!l p~s~u~e~ 10~ to b~
di~charged from port~ 106 again~t oppo~ite ~ide~ o~ the conic~l ~pray of paint issuing from nozzle 24. It i~ believed ~pparent that a~ air cylinder 66 is moved to the left from its Fig. 2 po~ition by manipulation of adjustment knob 96, tha ~ront wall 70 of air cylinder 66 will be advallced toward the inlet openin~ lOB
of pa~sage~ 104 and a8 the front wall 70 of cylinder 66 ~ov~
into contact with ths radial shoulder between counter bore~ S2 and 54 in the nozzle, the~e inlet opening~ will be progre~3ively block~d ~nd eYentually sealed by forw~rd wull 70. ~y adj~Atably po~itioning forw~rd w~ll 70 of ~ir cylinder ~6, a variabl~
re~triction to the flow of air through pass~ges 104 and the fanning port~ 106 is av~ilable. Thi~ control of the fannin~ i~
independ~nt o~ the rotative po~ition of ~ir cap 14 ~bout the nozzle ~xi~.
While one embodiment of the invention has been de~crib~d in detail, it will be apparent to those akilled in the art the di~closed embodiment may be modified. ~herefore, th~
foregoing de~cription i~ to be con~idered exemplary rather thall limiting, and the true scope of the invention i~ that defined in the following claims.

Claims (4)

1. In a paint spray gun including a housing, an annular air cap mounted at the forward end of said housing, said air cap having a central air discharge opening extending coaxially therethrough, nozzle means mounted on said housing coaxially of said air discharge opening, said nozzle means having a paint discharge orifice at its forward end for discharging paint under pressure its a forwardly directed stream coaxially of said air discharge opening, first passage means in said housing of supplying paint under pressure to said discharge orifice, second passage means in said housing for supplying air under pressure to said air discharge opening to atomize paint discharged from said orifice into a spray, and third passage means in said air cap communicating with said second passage means for discharging air from diametrically opposed parts in said air cap to control fanning of said spray;
the improvement comprising valve means in said housing adjustably movable between a fully open and a fully closed position for adjusting the flow of air from said second passage means to said third passage means, the atomizing air and fanning air being discharged from a single chamber formed in the air cap forward of the valve means prior to discharge into said second and third passages, respectively, and manually operable means independent of said air cap for adjustably positioning said valve means.

2. The invention defined in claim 1 wherein said first passage means comprises a hollow tubular member fixedly secured to and extending coaxially rearwardly from said nozzle means, and said second passage means comprises means defining an annular air chamber coaxially surrounding said tubular member, said air chamber having a pair of outlet openings defining inlets to said third passage means, and said valve means comprises an annular valve member slidably mounted for axial movement within said air chamber.

3. The invention defined in claim 2 wherein said air cap has a rearwardly opening bore in its rearward side coaxial its discharge opening terminately at its inner end at a rearwardly facing radial shoulder, the wall of said bore and said shoulder defining portions of the outer side and front end walls of said annual air chamber, said outlet openings being located at the juncture of said bore and shoulder, said annular valve member including an outer wall slidably received within said bore, an annular front wall on said valve member projecting radially inwardly from said outer wall at the front end thereof engageable with said shoulder on said air cap when said valve means is in said closed position to cover said outlet openings, said front wall having a central opening therethrough of a diameter greater than the outer diameter of said tubular member, and means at the rearward end of said valve member slidably received upon said tubular member.

4. The invention defined in either claim 2 or claim 3 wherein said manually operable means comprises a rod coupled at one end to said valve member, and means adjustably threaded into said housing coupled to the opposite end of said rod for shifting said rod relative to said housing in a direction generally axially of said annular air chamber.