US2416923A - Spray gun - Google Patents

Description

March 4, 1947. A. F. JENKINS .2,416,923

' SPRAY GUN l Filed Aug. so, 194,3 2 sheets-sheet 1 March 4, 1947. A F JENKlNs 2,416,923

' SPRAY GUN` A l Fi leld Aug. 30, 1943 2 Sheets-Sheet 2 /jz 7. @la

o /l K@ V 3mm www@ we@ Patented Mar. 4, 1947 SPRAY GUN Alexander F. Jenkins, Baltimore, Md., assignor to The Alexander Milburn Company, Baltimore,

Md., a corporation ofi'Maryland Application August 30, 1943, Serial No. 500,579

7 Claims.

In a spray gun of the type now generally employed for applying paint, enamel or other liquid coating material to surfaces for the purposes of protection, ornamentation, or the like, the liquid material is aspirated through a valve controlled orice disposed centrally of the forward face of the nozzle of the gun, by means of an .annular jet of air under pressure; and if a relatively flat or fan-shaped spray is required, convergent supplemental jets of compressed air are. directed through laterally disposed orifices in the nozzle so as to impinge upon the central jet of aspirated liquid and convert this substantially cylindrical or conical jet into one having an oval or even an approximately rectangular cross sectional configuration.

Heretofore, or rather until the conception of my invention covered by U. S. Patent No. 2,126,888, granted me August 16, 1938, the spray modifying jets have been in the form of solid cones emitted from ne circular orifices formed very accurately in the side portion of the nozzle so that the jets Will impinge exactly upon opposite sides of the axis of theI liquid jet. The liquid coating material is frequently also supplied to the. gun under some degree of pressure and valves for regulating the pressures and quantities of the liquid and of both the aspirating and spray modifying air supplies are generally provided on the guns. The degree of atomizationrequired,v the nature and viscosity -of the liquid to be sprayed, and the desired shape of the sprayal1 of these factors determine the degree of adjustment necessary for these regulating devices; and in most cases the relative pressures are quite critical and must be very accurately controlled.

In the use of spray guns of the usual type in which solid supplemental jets of spray modifying air are employed, there is a tendency to cause a split in the spray, that is, a narrowing' of the cross section of the center of the spray and a lessening of the densityof the spray at this point and an increase in density at the end portions thereof due to the unequal atomization of the sprayed liquid. To correct this condition, the usual practice, in constructions which permit it, is to reduce the supply of air to the supplemental jets. This adjustment, however, reduces the width of the spray and is apt to alter the 'fcharacter of the spray in otherl ways, especially when made in connection with the use of highly viscous and difficulty atomizable materials such as synthetic enamels and the like.

In the specification accompanying my Paten No. 2,126,888, I have described a spray gun in which tubular or hollow conical spray modifying jets of vair are provided, either alone or in conjunction with solid jets. By this means, a better atomization and distribution of the liquid material may be attained and the splitting eliminated, while at the same time there may be employed higher pressures or greater volumes of modifying air.

The present invention provides a modification of the nozzle disclosed in my. aforesaid patent, by means of which an even better atomization and distribution of the sprayed material may be attained.

The invention in its preferred embodiment contemplates the provision of ay substantially oval or elliptical annular opening or orifice for the spray modifying or fanning jets upon the wings of the nozzle. The long axes of the elliptical orices preferably extend transversely of the nozzle and the short axes are in alignment, and if extended intersect the axis of the main jet of the nozzle at the same point.

I have found that the provision of an oval or transversely widened orice produces a wide final spray of extraordinary uniformity, eliminating all spottiness or heaviifiess in the outer edges of the spray pattern. The use of a substantially oval spray modifying jet also renders both the air and coating fluid pressure regulation much less critical and actually reduces by a considerable amount the pressures required to produce an even pattern of adequate coverage.

`The objects of the inventionalso include novel methods and apparatus for providing and adjusting the orifice through which the oval annular spray modifying jet is emitted.

Other objects of the invention and features of novelty will be apparent from the following specification when read in connection with the accompanying drawings in which one embodiment of the invention is illustrated by way of the Figure 4 is an end View of a pin or plug employed to form the annular jet orifice; v,

Figure 5 is a View in side elevation of the plug; Y Figure 6 is a fragmentary View of the inner or forward Vface of one Vof the side wings of the nozzleshowing one form of annular oval orifice;

Figures '7, 8, 9, and 10 are similar views showing modifications in which the widths of the orice are varied at either the sides or ends thereof by either widening the opening in the nozzle or by narrowing the correspondingdimensions of the inserted pin; Y I

Figure 11 is a similar view showing the substantially oval orillce flattened on four sides Vto the shape of a lozenge;

,4 y ber32 formed between Vthe conical tip 25 of the liquid nozzle and the walls of the central air cap 35.

ThisV air cap 35V isprovided with the annular rearwardly extending flange v36 which lits around the annular flanged@ which extends forwardly from the portion 22 ,of the liquid nozzle; flange 35 extends rearwardly7 to fabut theY intermediate flange 22 of the liquid nozzle rand is pros Y vided with a radially outwardly directed flange I 30 which is spaced from the ange 22 so as to leave an annular space l3| into which a screw-- y driver or vother suitable tool may be inserted in Figures 12 and 13 are views in side end elevation respectivelyl'of a tool for placing or f centeringthe rinserts or pins in position'while they are being secured to the nozzles.v Figures 14 l5 yare similar views of a tool for adjusting the inserts in directions along the lon-g axis of the orifice; and l Figures 16 and 17 are similar views of Va tool y Vfor making adjustments along the short exis.

Referring `more particularly to Figure l of 'the drawings the numeral I0 designates the forward body portion of the spray gun whichmay be of any desired constructionso far as the actuatingV and controlling mechanism` is concerned. VFor,

example it may follow, except as indicated otherwise herein, the Vlconstruction. of the spray fgun illustrated in my Patent No, 2,269,0577Qdated Jane,

I The body portion of the spray gun is provided with a liquid chamber or passageway!! and a main air passageway ila. The air passageway is Y flange 44 of the clamping ring 45 may engage.

divided'adjacent the valve'seat i3V to provide 2 forwardly directed passageway I4 leading to the 'supplemental flattening jetsof the air cap and the diverging passageway l5 leading to the central aspiratingrairoriflces.V A'reciprocating valve Y member ,I2 cooperates withy the valve'seat 3 to ,,45

controlV the passage of air through the passage I4. The forward Vface l@ -of the body-portion of the gun is ordinarily formed in a .single plane,` although'within the scope of the invention the construction of the body vary widely. j Y

The inner liquid nozzle portion is indicated generallyl by the reference numeral-1320 and com- ,portion of the gun may order to remove the'cap or tip S5 from the liquid nozzle.- The flange ISB also provides an abut-` ment element for the surrounding inner portion vof Ythe annular' auxiliary jet air cap d2. VPrefIn erably the inner wall 355 of the liquid nozzle 20 is shaped as shown in Figure 1 and terminates shortv'ofY .the converging front walls of the cap 35 so as' to provide as much of anenlargement nozzle tip 25 at a predetermined distance'to pro? vider the annular aspirating air orifice de.

The' outer annular air cap of this Vtype of nozzle assembly is indicated generally by the reference numeral #i2 Yand is provided with vacen-l tral annular surface 3l which nts around the flange 35 of the supplemental air tip 25.' The air cap is provided rearwardly `with an outwardly extendingV anrnilarV flange 43 which forms a shoulder about whichv the inwardly directed The clamping ring 45 is threaded to the outer kkperiphery of an intervening annular thread carrying element H0 which isdisposed between the flange 22 of theV liquid Vnozzle and the forward face of the body of thegun. The'inner an- `nular surface HI of lthe insert Il@ fits around the central projecting portion H2 of thegfront `end kof the `gun and is sealed against therearward 'stepped face IIS of the body portionY il) as by means of the gaskets H5'. i

An inwardly disposed ring or washer tral air supply passing through the passageway E5 before it enters the passageways Se. The anprises the central rearwardly projecting nipple Y' which is threaded as at Y2l into'the recess IiiY formed in the forward portion I0 ofthe main' body of the gun. The centralportion of. the liquid nozzle20 is provided with a flange 22,1;he

nular intermediate member VI I Il is also'provided with the annular' recess or forward `annular chamber 20 which is placed Yin communication with the air supply passing through the passageway I rin the body of thegunby means of the series of Vholesl I 2l. An inwardly projecting flanged baille ring |22 and an outwardly projectperiphery of Iwhich may be squared for the appliv cation of a wrench or other suitable tool for. removing and-applying this portion of :the nozzle to the spray gun. The forward end of the liquid nozzlel proper is` of la general conical congurav v tion asl indicatedrat 25 and is provided centrally at the tip thereof with a liquid orifice 26, the flow of liquid through thisrorice. being, controlled byv ing ring |23 are fitted withinfthe chamber -IZ in order to equalize the distribution of the auxiliary jet air supply upon opposite 'sides' of the air means of the needle valve 2 which projects rear-` r wardly and is operatively connected with the trigger of thel gunwhich is not shown. herein, butv maybe of any usual or conventional construction or may bearranged as shown in my Patents Nos. 2,082,060 and 2,082,061. The intermediate flange` 22 isv provided with an annular series of passagen ways 30 which constitutea portionY of the comcap.

The,intermediate annular mem-ber H0 is provided around its outer periphery .with 4the'screw threads I'25 upon which may be screwed kthe clamping ring d5 which is provided with, the flange or shoulder 44 surrounding the shoulder 43oftheaircap. y r

At diarnetrically opposite points on the annu.- lar outer air cap 42v there are provided the forwardly directed outwardly' divergenty projections 50. These projections' areY of a substantially Vcircular or cylindrical"configuration and,v asbest shownin Figures ,1' andk 3, they 'are provided with rearwardly disposedv substantially cylindrical'r'e- Y The sie isV held bythe flange iii of the' member VI-lllso as Y through these faces with the rear recesses or` The chambers 52 are placedinI chambers 52. communication with the bailled air chambers l20 in the rearward portion of the nozzle of the gun by means of the parallel spaced ducts 54, the

rear ends of which open into the annular space,

i3d in the rear portion of the cap 42.

In order to close the rear end of the chamber 52 of the wings 5B of the nozzle cap, and also to shape the annular orifice in the forward faces of these wings there Aare provided the inserts or plugs 55. the outer headed portion 5B, a circular shoulder part 5l which fits snugly into the rear end of the recess or chamber 52, and the forwardly and inn wardly projecting pin portion 58 which is of an oval or elliptical cross section corresponding generally to the elliptical conguration'of the opening 53 in the wing projections 5U. The plugs 55 are inserted from the rear or outer side of the wings lill so that the parts 5l nt the chamber openings and the pins 53 are centered symmet rically with the openings 53. This` centering must be very accurately done, and special tools for accomplishing this purpose will be described. When properly applied and centered, the plugs are soldered firmly in place.

This arrangement results in the provision of a closed circular annular chamber into which the twin passageways 54 discharge air under pressure, and this air is then discharged through the oval or elliptical orices 8D provided in the faces of the wings. One of the resulting oval orifices 55 is very clearly shown in Figure 6 of the drawings. It will be noted that in the preferred embodiments the long axis of the ellipti cal orifice is disposed transversely of the nozzle, while the short axis lies in the same plane as the central axis of the spray gun. This arrangement has been found to provide an exceptionally satisfactory spray modifying jet which produces a uniform wide pattern which does not vary sharply with changes in air or coating fluid pressure. However, for some purposes it may be desired to arrange the long axis of the elliptical orifice in the plane of the axisof the gun instead of the short one, and this variation also comes within the scope of the present conception.A

In Figure 7, a modification of the uniformly wide annular spray jet orifice shown in Figure 6, is illustrated. In this arrangement the long diameter De of the opening 53 of the nozzle is maintained at substantially the same dimension as shown-in Figure 6 but the long diameter Dp of the pin 5ta is shortened, whereby there is provided oppositely disposed thickened portions 6|- at the ends of the orifice. This will afford somewhat more air at the ends of the spray pattern for certain conditions of operation. In Figure 8 the same effect has been attained by employing a pin 58 which is maintained at its original diameter shown in Figure 6, but the opening 53a has been lengthened as indicated al', D'o.

In Figure 9 of the drawings, the longer dimensions of both the pin 58h and the opening 53 have been maintained the same as in Figure 6, but the smaller diameter of the pin 58h has been narrowed as at dp, this providing widened portions 52 upon each side of the orifice.

A similar effect is attained as shown in Figure 10 of the drawings by maintaining the dimensions Each of these plugs is formed with' "of the pin 53 in both directions and by widening the opening 53D to the diameter do thus providing the widened portions on the longer sides of the orice.

In Figure l1 of the drawings, a substantially lozenge or rhombus shaped annular orifice 55 is provided by forming the nozzle opening 53e and Vthe pin 58e with corresponding cross sections.

This configuration may be employed where it is not so important to have theA spray pattern very wide at the ends.

In Figures 12 and 13 there is illustrated a tool l!! for use in positioning or centering the elliptical pins 58 which cooperate with thel side jet openings 53. The tool l@ is formed with a conveniently shaped shank 'il and a hollow or tubular portion '.12 of the exact shape of the orifice Sil. After the plug 55 is inserted into the chamber 52 and is roughly centered. by means of the shoulder portion 5l the end 'l2 of the tool It is inserted from the forward or inner side of the wing into the orifice 55 thus accurately centering the pin 58 within the opening 53. Then the plug 55 is soldered firmly in place and finally the tool 'lll is withdrawn.

In the event that after application to the device a pin 58 is found not to be properly centered, or if it becomes displaced through use, it may be recentered without dismantling the nozzle cap. In Figures lll and l5 an adjusting tool l5 is shown which has an operating end l5 in the form of a half-oval, shaped to fit within one of the longer halve-s of an orifice 5i?. This tool is employed in'cases where the pin 5t approaches the wall of Vthe opening 53 too closely at a point adjacent the ends ofthe longer diameter. By inserting the end 16 of the tool l5 and carefully exerting a gradual sidewise pressure, the pin 5S may be strained toward its properly centered position. On the other hand, if the pin 58 is warped too closely to the wall of the opening 53 adjacent the end of a short diameter, the tool Sii may be used, the end 3! being shaped to occupy a long halfoval portion of the orifice 6i).

It is understood that the construction and arrangement of ther central aspirating jet of the gun may be varied widely and still derive the substantial benefits and advantages of my novel oval modifying jets. The central jets may correspond to those in my aforesaid patents or may follow the design of any known or anticipated aspirating jet arrangement.

Various changes and modifications may be made in the embodiments illustrated and described herein without departing from the scope of the invention as defined by the subjoined claims.

Having thus described the invention, what is claimed as new and desired to' be secured by Letters Patent is:

1 In a spraying device of the class described, a nozzle comprising, in combination, means centrally thereof for discharging a liquid spray, and means disposed at each side of said first named means for discharging a tubular jet of air against said spray to modify its cross sectional conuration, said second named means each being so constructed and arranged that one diameter of said tubular jet is longer than the diameter at right angles thereto, the shorter diameters of the jets being co-planar and directed so as to intersect the axis of the central spray discharging means if projected.

'fa-natos Vvided axially thereof for discharging an atomized disposed means and directed so as to discharge holloW substantially tubular jets of air of elliptical cross section'toimpinge upon opposite sides of said spray at a point spaced from the face of the nozzle, in order to modify thecross sectional coniiguraticn of the spray, the shorter diameters of the elliptical orifices being co-planar and directed to intersect the axis of the nozzle if projected.

3. In a spraying device of the class described, a nozzle comprising, in combination, means provided axially thereof for discharging an atomized liquid spray, said nozzle also having an annular oriiice formed therein upon each side of said axially disposed means and directed so as to discharge hollow substantially tubular jets of air to impinge upon opposite sides of said spray at a l point spaced from the face of the nozzle, in order to modify the cross sectional configuration of the spray, said annular orifices having one diameter longer than the diameter at right angles thereto, the shorter diameters being co-planar and directed to intersect the axis of the nozzle if projected. Y

4. In a spraying device of the class described, a nozzle comprising, in combination, means pro-v vided axially thereof for discharging an atomized liquid spray, said nozzle also having an annular orice formed therein upon each side of said axially disposed means and directed so as to discharge hollow substantially tubular jets of'air to impinge upon opposite Vsides of said spray at a point spaced from the face of the nozzle, in order to modify the cross sectional configuration of the Y spray, said annular orices having one diameterv longer than the diameter at right angles thereto, the orifices being of lozenge shape,'the shorter` diameters being `co-planar and directed to interi sect the axis of the nozzle if projected.

5. In a spraying device of the class described, a

tion formed therein upon each side of said axially disposed means and directed so as to discharge hollow substantially tubular jets of air of elliptical, cross section to impinge upon opposite sides of said spray at a point spaced from the face of the nozzle', in order to modify the cross sectional convfiguration of the spray, the shorter diameters, of Y the elliptical orifices being co-planar and directed to intersect the axis of the nozzle if projectedthe annular elliptical orice -being wider at theends of its longer diameter whereby the elliptical'tubular air jets are correspondingly thickened.

6. In a spraying device of the class described,

a nozzle comprising, in combination, means provided axially thereof for discharging an atomized liquid spray, said nozzle also having an annular orice having a substantially elliptical cross section formed therein upon each side of said axially disposed means and directed'so as to discharge hollow substantially tubular jets of air of elliptical cross section to impinge upon opposite sides, of said spray at a point spaced from the face of the nozzle, in order to modify the cross sectional conguration of the spray, the shorter diameters of the elliptical orices being co-planar and directed to intersect the axis of the nozzle if projected the annular elliptical orice being wider at the ends of its shorter diameter whereby the elliptical tu- Y bular air jets are correspondingly thickened.,

7. In a spraying device of the class described, a nozzle comprising, in combination, means provided axially thereof for discharging an atomized liquid spray, said nozzle also having an annular orifice having a substantially elliptical cross section formed therein upon each side of said axially disposed means and directed so as to discharge hollow substantially tubular jets of air of elliptical cross section to irnpinge` upon opposite sides of said spray at a point spaced from the face of the nozzle, in order to modify the cross sectional con. guration of the spray, the shorter diameters of the elliptical orifices being co-planar and directed to intersect the. axis ofthe nozzle if projected the annular elliptical orifice being wider at the ends Vof one of its principal diameters than at the ends of the other principal diameter.

ALEXANDER F. JENKINS.

REFERENCES CITED The following references Aare of record in the 45 le of this patent:

UNITED STATES VParrains Number Name Date Y Y v2,126,889 JenkinsY Aug. 16, 1938 2,126,888 Jenkins Aug. 16, 1938 1,401,611 Landgrai Dec. 27, 1921 1,948,818 Kettering Feb. 27, 1934 1,463,332 Parker et al. 'July 31, 1923

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