US2304857A - Nozzle - Google Patents

Description

Dec. 15, 1942. R. STAHL 2,304,851

NozzIlE Filed March 25, 1940 INVENTOR A TTORNEYS'.

Patented Dec. 15, 1942 UNITED STATES APA'IHELN'T OFFICE NozzLE Application March 25, 1940, Serial No. 325,835

7 Claims.

The present invention relates to .spray appliances, adapted to spray paint, synthetic enamels and lacquers and the like, and in particular provides an improved method of, and apparatus for, projecting such material in a partially or completely atomized stream and thereafter converting this stream into an atomized spray 'of substantially elliptical or at crosssection. This application is a continuation in part of applicants prior application Serial N 119,563, filed January 8, 1937.

In spray appliances of the type to which the improvements of the present invention particularly relate, the material is conventionally projected from the tubular tip of a material nozzle, which nozzle is concentrically disposed within an outer or air nozzle. Air is caused to issue from the air nozzle in the form of a tube or envelope which surrounds the material stream. In certain instances, the flow of material is caused by the suction created by the issuance of the surrounding air stream, and in certain other instances, the material is caused to ow under externaliy applied pressure.

The air stream which surrounds the material stream commingles with the material 'and either partially or entirely atomizes it to thus produce a spray of generally circular cross-section. It has heretofore been proposed to subject this partially -or entirely atomized substantially circular spray of material to the -impact of two opposed and forwardly converging jets of air, which serve to hatten the stream and in certain instances to complete the 'atomization thereof.

The forwardly converging nature of the auxiliary ,-f-

air streams also serves to assist in projecting material spray forwardly against the object to ce coated.

In utilizing spray appliances of this character,

the operating costs are materially affected by the amount of air required per unit volume of the material that is sprayed, and the high spraying rates now commercially demanded, by, for example, the automobile manufacturers, has

able Values. The cost of the spraying operation is also materially aected by the degree of atomization thereof and by the uniformity thereof, it being appreciated that a spray which is incompletely atomized, and is of non-uniform density throughout the cross-section thereof re- .':uits in an irregular sprayed surface, requiring iatively expensive subsequent manual rubbing sanding operations.

In extending the prior nozzle constructions to caused the air supply costs to rise to objectionhigh spraying rates, it has been found necessary to materially increase the rates of iiow through the auxiliary nozzles. This is initially objectionable because of the increased air costs, and is A ladditionally objectionable .-in that it has been .found that the streams vof thus increased intens-ity serve to deforrn the material stream 'or spray from fa flat or oval shape to a dumb-bell shape. In certain instances, it has been found that the material is completely divided into two separate streams. In addition, particularly where the material being sprayed is 'of a non-homogeneous character, and includes nely divided particles of heavy materials such as are found in vitreous enamels, the convergent air jets ilick an unduly large part of the heavy constituents of the material out of the carrier liquid. This action causes an -objectionably large offspray, and also reduces the desired heavy or Vsolid particle content of the material. Various arrangements have been proposed with a view to overcoming these tendencies, among which are included the provision of additional auxiliary or supplemental air jets, which surround the previously mentioned main or central air jets and cooperate with the convergent auxiliary -air jets. This expedient, as will be appreciated, materially increases the required volume lof air, and complicates the structure by requiring the provision of a multiplicity of additional jets.

It Ahas been found, in accordance with the present invention, that the diiliculties above mentioned, as welll as others, rmay be effectively overcome, and a gun produced which requires a materially lower percentage of air ow per unit Yof material sprayed, by introduced bailles in the baths of. the auxiliary and convergent air jets. These bellies serve the purpose of modifying the forms of the auxiliary jets, and cause them to reduce the material stream to accurate elliptical vor hat form without introducing either .the irregularities mentiond above or causing the undesirable iiicking from the stream of any 4heavy particles which may be carried in the carrier liquid. In one form, the bail'les are so positioned that the auxiliary air jets, while deliected thereby and modied as above stated, lie in generally coplanar relation to the mai-n material stream. In another form the baflles are so formed and positioned relative tothe auxiliary streams, that they deflect at least a portion of each auxiliary air stream and cause these streams to separate and Vform a supplemental envelope around the material stream. 4

y With the above and other considerations in present invention;

view, objects of the present invention are to provide an improved method of and apparatus for producing an atomized flat spray of material, which is economical and reliable; to provide such a method which includes the use of one or more baflles interposed in the path of an auxiliary flattening air stream; to provide such a method in which baffles are utilized to deflect and modify the form of each of a plurality of auxiliary air streams, while maintaining them in co-planar relation to the material stream; to provide such a method in which baffles are utilized which deect and modify at least a portion of the auxiliary' air streams to cause them to ow in non-coplanar enveloping relation transversely of the material stream; to provide such a structure utilizing baiiles formed-as a part of the supporting structure for the auxiliary air nozzles; to provide such a structure utilizing baffles disposed on either side of and projecting from the nozzle adjacent the material and primary air outlet thereof; and to provide such a structure embodying an improved mechanical relation Vbetween-the gun body, an air nozzle, and a material nozzle.

With the above and other, as well as more Fig. 2 is a view in perspective of the nozzle Istructure of the gun of Fig. 1;

Fig. 3 is a view in vertical longitudinal center section oiV the nozzle structure Shown in Figs.

1and2; I Y

Fig. 4 is a View in end elevation, taken along the line 4 4 ofFig. 3;

Fig. 5 is a view corresponding generally to Fig.

A3, but illustrating the air and material streams;

Figs. 6 and 7 are diagrammatic views of jet forms, taken respectively along the line 6,-6 of `Fig. 5 and 1-1 of Fig. 5;

Fig. 8 is a diagrammatic view of a material stream, illustrative of the improvements of the Fig. 9 is a view in perspective of Ya nozzle construction embodying a modification of the invention;

Fig. 10 is a view in vertical longitudinal section of the nozzle structure shown in Fig. 9;

Figs. 11 and 12 are diagrammatic views of air and material stream forms taken respectively `along the lines II-II and I2-I2 of Fig. 10; and

ally an air nozzle 20, hereinafter described in more detail; Va barrel 22; a handle grip portion 24; a trigger 26; vand suitable material and air 'inlets 28 and 29. The nozzle 20 is removably secured to Vthe barrel 22 by a connector or collar 30, and encloses the hereinafter described material nozzle. It will be appreciated that with the 'trigger 26 in the illustrated position, both the ,material and air inlets are closed off, and that,

in order to place the gun in operation, the trigger 26 may be swung in a counter-.clockwise direction as viewed in Fig. 1, the resultant degree of open'- ing of the material inlet being adjustable by means of a conventional adjusting head 34. A

corresponding conventional adjusting element 32 is provided for the air inlet.

Referring more particularly to Figs. 3 and 4, the barrel 22 is bored to provide a longitudinally extending material supply passage 40, and a parallel longitudinally extending air supply pasyenol of the barrel is provided with two annular counterbores or recesses 44 and 45. The recess 44 communicates through a valve opening 46 with the air supply passage 42, and the recess 45 communicates therewith through a passage 4T; 'Ihe effective area of the valve opening 46 is disposed to be regulated by a needle valve formed at the end of a valve rod 48, which, in turn, is disposed to be actuated by an adjusting head 34 disposed exteriorly of the gun so as to permit the supply of air to the auxiliary air jets, to be more fully described later, to be controlled so as to enable the pattern of the ejected spray to be varied. The supply of air to the passage 42 is controlled by a valve (not shown) mounted within Vthe gun in a conventional manner, and this valve,

together with the valve controlling the paint sup'- ply, is controlled by thel trigger 26. The recess 44 forms a distributing chamber to distribute the air supplied through the passage 42 to each of two x hereinafter described a-uxiliary air nozzles B, provided in the horns 52 of the nozzle 20, and the recess 45 forms a distributing chamber through which air is supplied to the central or main air nozzle A.

The hollow or tubular material nozzle 54 is pro-v vided with an externally threaded shank 60,' by "which itis secured within the correspondingly threaded outer end of the barrel 22, and is also provided with an enlarged head 62, the external surface of which is conical. The outer end of the material nozzle 54 includes a tapered portion 64,

and terminates in a nozzle or tip, the side walls of Vwhich are preferably of uniform internal diV` ameter and, define the material nozzle M. The

conical end 68 of the needle valve 'l0 seats against the rear end of the nozzle M. The needle valve 10, as has been mentioned, is disposed for actuation by the trigger 26 of Fig. 1.

The inner face of the enlarged portion 62 of the material nozzle 54 is provided with a pair of annular ribs T2 and 'I4 which bear againstthe.

outer end of the barrel 22. `The rib 14 abuts the portion 16 of the barrel which lies between the annular recesses 44 and 45, and thus isolates these recesses from each other. The rib 'I2 bears against the portion 18 of the barrel 22.

The air nozzle 20 is in theform of an inwardly`V presented cup, the inner walls 9B of which are nozzle.

portioning of the parts is such that a chamber 92 is provided between the inner surface of the air nozzle 20 and the outer end of the material nozzle 54, which chamber communicates with the previously mentioned recess 45 through a'plurality of longitudinally extending passages 94 formed in the material nozzle 54. The walls`96 of the air nozzle 20,. which yare opposite the. tapered' Wall portions 64 ofthe material nozzle, are correspond'- ingly taperedy and spaced therefrom. The-` Wall portion 9B terminates in a short section 981 the inner surface of which isv preferably slightly convergent and, with the tip of the' material nozzle, defines an annular nozzle or orice A through which a tube or envelope of air maybe discharged around the stream of. material emitted through the opening M. The base-of the nozzle illl-v is pro'- Vvided with a shoulder 9i which is engaged by a flange 93 on the collar 30, to retainY nozzle 20 in assembled relation.

The means for providing the auxiliary jets of air which are utilized in the present construction to control the form of the atomized material stream, as well as to complete itsatomization, include the passages 50 which extend longitudinally of the two diametrically opposed horns 52 of the air nozzle 2li', and a pair of convergent passages 100 which communicate with the longitudinal passages 5i?, respectively, and terminate in nozzles B.

In order to modify the effect of the auxiliary streams of air, baffles are introduced in the paths 5 thereof as previously mentioned, and in the embodiment now being described, these bailies are formed as part of the horns 52. Each baille includes a surface 02 disposed as a continuation of and at substantially the same angle as the corg.

responding convergent passage Hill. The inner surfaces of the baffles are undercut, as indicated at E04, which undercutting produces an area of relatively low pressure immediately behind each auxiliary jet of air.

The remaining mechanical features of the structure above described may best be considered with reference to a description of the operation of `the unit. It will be appreciated that the material to be sprayed, and admitted through the inlet 28 to the barrel passage 40, may be supplied under pressure, or that, alternatively, the discharge of material from the material nozzle M may be caused by the suction produced by the primary air stream discharged through the air nozzle A. To open the nozzle M, the trigger 26 may be moved in a counterclockwse direction, asviewed in Fig. l, thus withdrawing the valve A,rod lil. This movement of the trigger also admits air to the longitudinal barrel passage 42 by open*- ing the conventional air valve (not shown). The auxiliary air valve' 46 is assumed to have already been adjusted to its properly opened position, but it may, of course, be adjusted during operation of the gun to vary the pattern of the spray to suit r the desires of the operator. The circuit for nozzle A extends from passage 42 through passage 41, around recess 45, passages 94, and thence through chamber $2 to nozzle A. The circuit for' nozzle B extends through valve 46, around recess 411:, and thence through passages 50' and |001.

In response -to the above action, a solidv sub'- stantially circular stream of material. in a liquid state is continuously emitted from the material nozzle M, which stream is` surrounded and enveloped by a tube or envelope of air emitted from the circular air nozzle A.v As will be appreciated, the arrangement and proportioning of the air and material nozzles and of the pressures at which the air and material streams emerge from the corresponding nozzles are so proportioned that the enveloping and slightly convergent tube of air from the nozzle A acts to atomize the stream of material and transform it into a ne spray. In

-certain instances it is desirable to effect the complete atomization` by' the primary air stream, While Y in others', as in the present case; the atomization is' intensied and completed by the auxiliary air streams.

It has heretofore been proposed to so arrange andv form the air nozzle, corresponding to the nozzle A in the present instance, that the primary tube orgenvelop'e of air acts to itself modify the 'shapeor pattern of the material stream, as well as to atomize this stream.. In the present instance, however, it is preferred to conne the function: of the air stream A to the atomization only andl rely solely on the auxiliary jets to modify the pattern.

Concurrently with the flow of atomizedV material through the nozzle M, surrounded by the envelope of air from the nozzle A, and at a rate determined by the opening of the valve G6, as well as by the material and air pressures, two auxiliary streams of air are discharged through the convergent nozzles B, as diagrammatically shown in Fig. 5, and impinge upon the material stream at a point slightly beyond the point at which the atomizing effect of the primary air stream is begun. The two auxiliary streams of air impinge upon the material stream at diametrically opposed points and. have the effect of not only modifying this stream from its original circular form to the oval or elliptical form shown in Fig. 8, but also to intensify the atomization of the material being discharged from the nozzle M. As will be appreciated, the precise relation between the major and. minor axes of the oval b may be controlled bythe relative intensities and volumes of the material stream and the two auxiliary air streams, and it is found in the practice of the present invention that this relation may be varied between relatively wide limits.

As previously mentioned, nozzles heretofore made, of which the present applicant is aware, utilizing auxiliary` streams of air such as are emitted through the nozzle B in the present instance, have been objectionalole in that a tendency is present to deform the material stream from the oval shape b of Fig. 8 to the dumb-bell shape shown in dotted lines c in the same gure, when the volume of air admitted through the auxiliary nozzles is increased to the eXtent required to obtain the desired l'iness of atomization particularly when spraying material of a heavy or a nonhomogeneous character and particularly where such material includes finely divided particles of heavy materials such as are found in vitreous enamels. A tendency is also present, particularly when utilizing material which includes relatively heavy solid particles, to flick an unduly large proportion of the solid particles out of the stream where the volume of air through the auxiliary nozzles is thus increased. This action forms an undesirably large olf spray, and also reduces the proportion of the solid parti-cles and renders the spray non-uniform ln cross-section.

These ldifficulties are entirely overcame in the practice of the present invention by the provision of the baille surfaces 02. As is shown diagrammatically in Fig. 6, the baille surfaces H12 act to relatively reduce the intensity of and spread the streams of auxiliary air. In passing over the lower edges or lips of the baille surfaces U52, the auxiliary air streams are slightly bent inwardly and laterally spread as indicated in Fig. 5, and it is found in practice that after leaving the baille surfaces, the auxiliary air streams may assume an oval shape 3 as shown in Fig. '7. In. certain cases, depending upon the precise shape of the olds or the like.

Vin'n'er edges of the baille surfaces',` the streams may assume the kidney shape indicated by the dotted line f in Fig.' 7. The baffles thus serve to modify the shape of the auxiliary streams and by'enlarging the cross sections thereof reduceY the relative rate of flow, and consequently reduce the intensity with which they would otherwise impinge upon the material stream if'their volume was increased over conventional practice tothe point necessary tov obtain the desired neness of atomization of heavy materials such as enamel- The material stream is thus bathed, so to speak, inthe auxiliary air streams and is flattened thereby to oval form without introducing the irregularities indicated in Fig. 8, and without such intensity of ow as would cause undesirable flicking out of any solid particles in the material as would happen in Vconventional vconstructions if the volume of flow through the auxiliary nozzles was increased to the desired ex-V tent. The Volume of air through the auxiliary f B open, are undercut so that the auxiliary streams of air are entirely unconned in the regionjbe-Y nozzles may thus be increased to an extent, as

compared to conventional constructions, as to intensify the atomization of the paint or like material ejected from the main nozzle toV obtain i;

the desired neness of material, without the dan-l ger of flicking particles of solid material out of the character as small openings which might be constantly plugging up in service.

In the modified embodiment of the invention shown in Figs. 9 and 10,v the baille surfaces |02 are replaced by baille surfacesY I which project in diametrically opposed relationship from the outer end of the air nozzle, adjacent the axial center thereof. As shown in Fig. 11, the outer surface ||2 of each baffle ||0 is arcuate in form, and the breadth of each baille is substantially in excess of the diameter of the central air nozzle A. The outerends of the bailles I |0 are disposed in thev path of and intersect a certain portion of the auxiliary convergent streams of air flowing through the nozzles B. The portions of the auxiliary streams which are not intercepted by the baille plates l0 impinge upon the material stream and serve to flatten it. The portionsy of the lauxiliary streams which areV intercepted by the baffle plates |10 are deflected thereby and are caused to flow outwardly thereover, in the manner indicated diagrammatioally in Fig, 11 and in an enlargedscale in Fig. 12. This outward or transverse flow kof air serves to draw the material ably such that the auxiliary streams impinge upon the material stream at a point slightly beyond the point at which the atomizing effect of the main or central air stream is initiated.

In the modified embodiment of the invention shown in Fig. 13, bailles are provided which are in the p'ath'ofY and are'imping'ed by the auxiliary streams of air discharged through the Vauxil-iary air nozzles B, inthe same general relation asin the embodiment of Figs. 1 through 8. In

the embodiment-of Fig. 13, howeventhe nozzle" surfaces |22, through which the nozzle openings tween each nozzle opening B and the corresponde ing baille |20. It will be recalledthat in the embodiment of Figs. l `through 8, the auxiliary streams .of air travelalong the baille surfacesV lare entirely unconfined from the time they leave Y the nozzle openings B until they impinge upon the baffle surfaces |20, the effect of the. baille sur# faces |20 is vsomewhat more pronounced.

Except in the structural respects just mentioned, the embodiment of Fig. 13 may, and preferably does, duplicate the structure of Figs. ,1 through 8, and it will be understood that except in the respects noted, the operation of the two embodiments is also the same. That is to say, that part of each auxiliary air stream which im-V pinges upon or passesdirectly over a baille surface is deflected, in the plane of the paper, as viewed in Figs. 5 and 13, for example, toward the material nozzle. In -other words, the width Vof the air streams in the just-mentioned plane is increased, thereby correspondingly increasing the length of the zone in which the auxiliary air streams are effective to act upon the material stream.

Although specic structural embodiments Vof the invention and specic methods of practicing it have been described, it will be appreciated that various modifications in the form and arrangement of the structures, and various changes in the methods, may be made within the spirit and scope thereof.

What is claimed is:

1.' In a nozzle structure for a device of the class described, the combination with a material nozzle for'forwardly projecting a material stream, and a pair of auxiliary air nozzles for directing auxiliary air streams against said material stream transversely thereof, of a pair of diametrically opposed baille platesv disposed at opposite sides of and in forwardly extending relation to said material nozzle, said auxiliary air nozzles being positioned radially outwardly of said baffle plates, said baille plates acting to break the associated air streams in two parts flowing substantially in a plane paths respectively of said air streams and being z positioned radially inwardly of .said nozzles.

3. In a nozzle structure for a device of the class described, the combination of a material nozzle for forwardly projecting a material stream, a pair of auxiliary air nozzlesV fordirecting air streams against saidV material stream transversely thereof,

said auxiliary nozzles being so positioned that the axes of said air and material streams are substantially co-planar, and baille means disposed between said auxiliary and material nozzles, said baille means having surface areas positioned for direct impingement by said air streams, said baille means being abruptly cut away adjacent the forward auxiliary air streams to modify the form of the auxiliary air streams before such air streams impinge upon the material stream.

4'. In a nozzle structure for a device of the class described, the combination of a material nozzle for forwardly projecting a material stream, a pair of auxiliary air nozzles for directing air streams against said material stream transversely thereof, said auxiliary nozzles being so positioned that the axes of said air and material streams are substantially co-planar and baille means disposed between said auxiliary and material nozzles, said baflle means having surface areaspositioned for direct impingement by said air streams, said baille means being abruptly cut away adjacent the forward edges of said areas so that such edges are relatively sharp, said nozzle structure beingso constructed and arranged that said auxiliary air streams are unconned in the region between the corresponding nozzle opening and the corresponding baille means, and said baille means acting to modify the form of the auxiliary air streamsI before such air streams impinge upon the material stream.

5. In a nozzle structure for a device of the class described, the combination of a material nozzle for forwardly projecting a material stream, a pair of auxiliary air nozzles for directing air streams against said material stream transversely thereof, said auxiliary nozzles being so positioned that said air and material streams are substantially coplanar, and baille means positioned between each auxiliary air nozzle and the material nozzle for direct impingement by the corresponding air stream, each baille means comprising a surface forming a continuation of the corresponding air nozzle opening and having a relatively sharply undercut forward edge over which the corresponding air stream flows after said impingement, said baille surfaces and said auxiliary air nozzles being so constructed and arranged as to be ineffective to interfere with expansion of the corresponding air stream transversely of said plane, and each said baille surface serving to widen the corresponding air stream in said plane.

6. In a nozzle structure for a device of the class described, the combination of a material nozzle for forwardly projecting a material stream, a pair of auxiliary air nozzles for directing air streams against said material stream transversely thereof, said auxiliary nozzles being so positioned that said air and material streams are substantially coplanar, and baille means disposed between said auxiliary and material nozzles, said baille means having surface areas positioned lfor direct impingement by said air streams, ,said baille means being abruptly cut away adjacent the forward edges of said areas so thatsuch edges are relatively sharp, said baille means including a baille surface in the line of flow of each air stream, and said nozzle structure being so constructed and arranged that each air stream is unconned in the region between the corresponding baille surface and the corresponding air opening.

7. In a nozzle structure for a device of the class described, the combination of a material nozzle for forwardly projecting a material stream, at least one auxiliary nozzle positioned radially outwardly from the axis of the material nozzle for directing an air stream against said material stream transversely of the latter, and baille means disposed between said auxiliary and material nozzles and in the plane of said auxiliary and material nozzles, said baille means having a surface area positioned for direct' impingement by said air stream, said baille means being abruptly cut away at the forward edge of the said area so that said edge is relatively sharp, said nozzle structure being so constructed and arranged as to not interfere with expansion of said air stream transversely of said plane in the regiori between the auxiliary nozzle opening and the baille` means, and

said baille means acting when impinged by said auxiliary air stream to modify the form of the air stream before such air stream impingesupon the material stream. jl

` RODOLPI-IE STAHL.

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