US2126888A

US2126888A - Spray gun nozzle

Info

Publication number: US2126888A
Application number: US81952A
Authority: US
Inventors: Alexander F Jenkins
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-05-26
Filing date: 1936-05-26
Publication date: 1938-08-16
Anticipated expiration: 1955-08-16

Description

-Aug. 16, 1938. A. F. JENKINS SPRAY GUN NOZZLE 2 Sheets-Sheet 1 Filed Hay 2,6, 1936 Aug. 16, 1938. A. F. JENKINS SPRAY GUN NOZZLE Filed May 26, 1936 2 Sheets-Sheet 2 E MM@ gmc/whom Patented Aug. 16, 1938 UNITED STATES PATENT OFFICElv SPRAY GUN NOZZLE .Alexander F. Jenkins, Baltimore, Md.

Application May 26,

18 Claims.

This invention relates to spraying devices and has for its general object the provision of improvements in the nozzles of such devices whereby better atomization and distribution of the liquid material employed may be attained.

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 conguration. l

Heretofore the spray modifying jets have been in the form of solid cones emitted from fine circular orices formed very accurately in the side portion of the nozzle so that the jets will impinge exactly upon opposite sides of the axis of the liquid jet. The liquid coating material is frequently also supplied to the vgun 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 atomization required, the nature- 'and viscosity of the liquid to be sprayed, and the desired shape of the spray,-all 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 1. 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 density of 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 character of the spray in other ways, especially when made in connection with the use of highly viscous and difiicultly atomizable 193s. serial No. 81,95?.

(Cl. zml-140.1)

materials such as synthetic enamels and the like.

I have found that by the provision of tubular or hollow conical spray modifying jets of air, either alone or in conjunction with solid jets, 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; and this comprises an important feature of the present invention. This improvement also aifords wetter and more uniform coatings and wider spray patterns, and permits the more effective atomization of heavier coating materials, such as the synthetic enamels to which reference has been made, which are more didicult to break up or atomize than the ordinary paints or lacquers.

It has also been found that the pressures and volumes of air may be varied within rather wide limits. without necessitating the fine adjustment of the supplemental spray modifying air supply which has always been necessary in the case of the use of solid jets.

The hollow supplemental air jets are produced in the preferred embodiments of my invention by the provision of -one or more annular orifices in the side portions of the spray gun nozzle or by the use of annular orices together with a concentric circular orifice. Several ways of forming these orifices are disclosed herein, but the invention is of course not limited thereto but comprises all variations or modifications which may fall within the scope of the subjoined claims.

Another advantage accruing from the use of a hollow tubular or conical air jet resides in the fact that such extreme accuracy in machining the orifices to produce this type of jet is not necessary as in the case of the circular orifices employed for the projection of the solid jets.

Another readily appreciable eil'ect of this novel feature is the uniform atomization of the material at the extreme ends of the generally elliptical spray patterns produced.

Another feature of my invention which may be applied to the spray gun nozzle, either alone or in conjunction with the annular supplemental jet orifices, is the provision of a central aspirating air orifice with a serrated marginal periphery. This construction is particularly effective when employed in connection with the annular side jets, since both of these features cooperate to produce an advantageous softening and diffusing effect on the spray.

A further feature which is especially useful in connection with the somewhat numerous modications in the form of the air jets, is the provision of a novel type of nozzle air cap. This air cap is made up of two parts, one preferably being threaded for application to the body portion of the spray gun and of standard construction, size and proportions; and the other part being secured to the rst named part and being of variable construction embodying any one of the different forms of aspirating or supplemental air jet orifices described.

Other objects and features of novelty will be apparent from the following specification when taken in connection with the accompanying drawings in which several embodiments of my invention are illustrated by way of example.

In the drawings:

Figure 1 is a vertical longitudinal sectional view through the forward body portion and nozzle of a spray gun embodying the principles of my invention;

Figure 2 is a view in side elevation of the air cap forming part of the nozzle;

Figures 3, 4, 6, g-'l and 8 are fragmentary vertical longitudinal sectional-views throughportions of the nozzles of spray guns showing other ernbodiments of my invention; l

Figure 5 is a fragmentary plan yiew of the /face of one of the horns of the gudshown in Figure 4;

Figure 9 is a similar fragmentary view of the same portion of the embodiment illustrated in Figure 8;

Figure 10 is a view in front elevation and Figure 11 is a fragmentary front View showing respectively two alternative forms` of central orices adapted to cooperate with any of the modifications of the supplemental jets shown; and

Figure 12 is a chart showing diagrams of the spray patterns produced upon a surface by the designated types of nozzle.

Referring more particularly to Figure 1 of the drawings the numeral I0 designates the forward body portion of the spray gun which may be of any desired construction so far as the actuating and controlling mechanism is concerned. For example, it may follow, except as indicated otherwise herein, the construction of the spray gun illustrated in my Patent No. 2,082,061, dated June 1, 1937, filed January 12, 1935. The forward body portion I0 is provided with an internally threaded boss II which is adapted to receive the usual flexible connections by which Comunication is established with a source of supply of liquid coating material, with which the passageway I2 communicates. A recess I4 is provided in the forward face I5 of the body portion I0 of the gun and is connected with the passageway I2 by means of the bore I6. Threaded as at I8 within the recess I4 is the liquid nozzle 20 which is provided with an axial bore 22 tapered as at 23 adjacent its forward end and narrowed at the extreme forward end to provide the relatively small central liquid port 24. A needle valve 25 is disposed within the bore 22 and is provided with a tapered and attenuated forward end 26 which serves to regulate the port 24. The needle valve 25 is extended rearwardly through the bore 28 formed in thebody portion I0 of the gun and projects through the stuffing box arrangement 29 and is extended rearwardly to be connected to the regulating and actuating mechanism not shown.

In this illustrative embodiment a common air passageway 30 is provided in the body portion I0 of the gun which is provided rearwardly of the illustrated portion with suitable actuating and controlling mechanisms. At the forward end of the gun the passageway 30 diverges to provide two short passageways leading to the front face I5 of the gun. These passageways are designated by the numerals 32 and 33, the former providing means for supplying the air to the laterally disposed spray modifying jets and the latter supplying the air to the central aspirating jets of the nozzle. The mouth of the passageway 32 forms a valve seat 34 which is controlled by the needle valve 35 having the rearwardly extending stem 36 and adapted to be controlled by mechanism carried by the rearward body portion of the gun and not illustrated in the present disclosure.

The liquid nozzle member 20 is provided with an enlarged tapered frusto-conical portion 38 at the base of which there is `formed a preferably hexagonal nut portion 39 by which this member may be threaded into the body portion of the gun. The outer peripheral portion of the conical liquid nozzle is provided with a circular series of small passageways 40 which communicate with the annular recess 42 formed between an outer enlargement of the recess I4 and the stem of the liquid nozzle. The air passageway 33 communicates with this annular chamber 42 and the connection is sealed by means of the small gasket 43 which is adapted to be compressed between the rear face of the enlarged portion 38 of the liquid nozzle and the face I5 of the spray gun.

A two-part outer nozzle cap 45is provided,which for purposes of description in connection with its functions and relation to the other elements of the gun, may be considered unitary. This cap has an internally tapered portion 46 seating upon the conical outer surface of the enlarged portion 38 of the liquid nozzle. An annular flange or shoulder 48 is provided on the cap around which is fitted a clamping collar 49 which is threaded as at 50 around the forward body portion of the gun. Centrally of the forward portion of the nozzle cap 45 an opening is formed through which the narrowed projecting end 53 of the liquid nozzle extends. The end of the liquid nozzle fits the opening with ample clearance to form an annular orifice 52. Between the forward portion of the cap 45 and the liquid nozzle there is formed an air chamber 54 which provides communication between the circular series of passageways 40 and the annular aspirating air orifice 52. Certain novel features of the present invention which involve the shape of the annular orice 52 will be described hereinafter.

Upon diametrically opposite sides of the nozzle cap 45 there may be formed the projecting bosses or horns having diverging faces 6I within which are formed the orices through which are emitted the converging jets of spray modifying air which impinge upon the central spray projected axially of the gun in order to flatten and control the shape of the spray pattern. In all of the illustrated embodiments, each of the horns 68 is provided with bores within which may be disposed devices for altering the configuration of the spray modifying jets in accordance with the various phases of the present invention. In the rst embodiment illustrated in Figure 1 the bore is designated and is provided with a narrowed forward portion 66. Each bore 65 is placed in communication with the air supply by means of the rear passageways 68 leading from the annular chamber I0 formed between the face I5 of the body portion of the gun, the liquid nozzle, the rear face of the air cap 45. and the clamping 'sleeve 49. This space or chamber 10 is pro-- vided with its air supply by means of the passageway 32 controlled by the valve 35 which has already been described.

In the embodiment illustrated in Figure 1, the bores 65 provided in the horns 60 are continued through the rear inclined faces 13 of the horns so as to provide means for the insertion of the plugs 14 which are provided with the forwardly and inwardly projecting pins 15. These pins 1l are of a smaller diameter than the forward portion 66 of the bores 65 and thus provide annular passageways 16 forming oriiices through which the tubular or hollow conical blastsof air are directed toward the central axial spray. The plugs 14 are formed so as to iit tightly within the rear portion of the bore 65 when driven therein.

The improvement provided by means of the present invention in the aspirating and initially atomizing means for the liquid material will now be described. Instead of the usual circular opening in the forward face of the cap 45 surrounding the tip of the liquid nozzle there isemployed in the present nozzle, either in connection with modifying jets of the prevalent solid character or with any of the improved modifying jets provided in connection with the present invention, an orifice of irregular periphery. 'I'his feature involves providing kerfs or serrations in the periphery of the central opening of the vcap to provide the annular port or oriilce 5-2 with a serrated margin. These serrations or kerfs are illustrated in two forms at and 80 as shown respectively in Figures 10 and 1l of the drawings. The indentations 80 are in the form of rectangular kerfs provided in the outer peripheral margin of the orice and the indentatio'ns 80 are in the form of triangular serrations providing a somewhat starshaped oriiice. By this means the margin of the aspirating jet of air is not so sharply defined but is broken up to some extent for the purpose of securing better atomization and a softening effect on the spray. 'I'his feature is of some utility even when employed alone or in connection with the old solid modifying air jets, but has been found to be of especial importance in connection with the somewhat more diuse hollow tubular or conical modifying air jets provided in accordance with the present invention. v

In Figure 3 of the drawings there is illustrated an embodiment of my invention wherein the conguration of the horns 60 and their bores 65 is the same as in the case of the embodiment shown in Figure 1. However, the plug 14 is provided with a hollow pin or projection 15' with an axial bore 82 provided therein. Ihe base of this bore 82 is placed in communication with the bore 65 by means of one or more holes 04 formed in the hollow pin 15. By this means, compound jets of spray modifying air may be projected toward --the axial liquid spray, each comprising an inner solid jet surrounded by an external tubular jet of air.

In Figures 4 and 5 of the drawings there is illustrated a modication in which the bore 65 is not extended through the rear face oi' the horn 60 but the base of the bore is provided with a narrowed socket or recess 86 within which a pin 88 is adapted to seat preferably with a driving t. The pin 88 is provided with a polygonal enlargement 89, being in the form of a triangle in the illustrated embodiment, which serves to center the pin Il with respect to the bore 65' to maintain the uniformity of the annular port or orifice 10.

In Figure 6 a somewhat similar arrangement is shown in which the pin 80' is seated within a socket or recess .86' and is centered by means of an annular flange 89- through which a series of holes 90 are formed for the passage of air to provide the tubular jet issued from the annular orificek 16.

In Figure '1 a removable pin 15 is employed which is provided upon its rear end with a threaded enlargement 92 adapted to vbe secured within the threaded recess 93 formed in the rear surface of the horn 60, and also a kerfed head 95 for the application of a tool whereby the pin 15 may be removed and replaced.

In Figures 8 and 9 of the drawings there is illustrated a still further modication in which a plurality oi annular openings are provided through which may be discharged concentric tubular blasts of air. The plug 14 in this embodiment is provided with a forwardly projecting pin 15 and also a tubular sleeve 96 is threaded into the plug 14' as at 91. This arrangement provides two annular orifices16 and 16. Communication is provided between the inner and outer bores in this embodiment by means of one or more openings 98 formed in the tubular member 06.

For the purposes of convenience and economy in the quantity production of these nozzles they may be formed in two parts as clearly shown in the sectional views in the drawings and also as will be pointed out in connection with Figures 2 and 10. This feature also'ifacilitates the application of the attaching collar 49 tol the air cap. The rearward portion of the cap 45 to which the collar 49 is applied is of a generally annular configuration and is designated by the reference character |00. This portion may be of standardized construction and dimensions regardless of the type of vorifices used. The forward portion of the cap hasa narrow rectangular outline when viewed from the front, and is adapted to carry the iiuid projecting portions of the nozzle which may be of any of the types shown and described herein.

As best seen in Figure 2 of the drawings the conical forward face |02 of the portion |00 is provided with jthe central transverse slot or groove |03`within which the portion |0| is disposed. Each end of the latter portion is provided with overhanging shoulders |04v by which its transverse position is determined, so as to provide proper registry for the several portions of the passageways 60 and the chamber 54 which are intersected by the dividing surfaces denoted by the line |05, between the two cap portions |00 and |0|.

Any suitable means may be employed for securing these two portions together; one of these means being by soldering them at the points indicated by the reference character S. By making the cap in two parts, the ready substitution of one type of orifice for another may be attained and the assembling of the air cap 45 and its retaining ring 49 is made easier. On account of the projecting horns 60, in the air cap of the ordinary type, the flange of the retaining ring must be spun over the shoulder 48 of the air cap. This necessity is of course eliminated in the present case, the forward orificed member of the air cap being applied and secured in position after the ring is in place.

In Figure 12 there is shown a chart wherein there are graphically illustrated the types of spray patterns produced by devices constructed in accordance with the present invention as compared with those employing solid modifying jets. In the diagram designated I in the chart, there is represented a spray pattern produced by a gun of the type described in the present invention in which annular spray modifying jets are employed. In producing this pattern the air pressure was adjusted to 75 lbs. and the pressure upon the liquid coating material was 3 lbs. The .air valves of the gun including the valve designated 35 in Figure 1 of the drawings were opened to their widest extent and it will be noted that the spray pattern is represented by an elongated oval area in which the atomization was uniform substantially throughout.

The pattern designated II was made by a spray gun of comparable specifications, except that solid modifying air jets were employed. The air pressure and the liquid pressure were the same as that employed in connection with the production of the pattern designated I and all air valves were opened wide. It will be noted that the pattern is narrowed at its central portion and the spray is heavier at the side portions of the pattern than at the center, the tendency toward splitting" being very apparent.

In an effort to correct this tendency, the usual practice is to cut down the pressure and volume of air supplied to the supplemental spray modifying jets by regulating the valve 35. Such an eiiect is illustrated in pattern No. III. Here, it will be noted, the spray pattern is again of a fairly uniform atomization but has been narrowed to a very great degree, this, of course, reducing the coverage and increasing the labor required to apply the coating.

In the pattern designated IV, 100 lbs. of air and liquid coating material under 4 lbs. pressure were applied to a spray gun employing solid supplemental air jets, and the tendency toward splitting is quite extreme in this case.

On the other hand, the pattern shown in diagram V illustrates the result of employing the same pressure conditions as in the case of pattern IV in a gun constructed in accordance with the present invention in which annular supplemental jets are provided. It Will be noted that there is little or no tendency toward splitting and the atomization is very uniform and the width of the spray pattern is not reduced.

Although several variant forms of my invention have been illustrated and described, it is conceivable that further modifications may be made therein and, within the scope of the claims, such variations are to be considered as coming within the purview of the invention. It is further understood that the proportions or relative sizes of the various elements and orifices are not limited to those illustrated but may be varied within Wide limits.

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

l. 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 one side of said first named means for discharging a tubular jet of air against said spray to modify its cross sectional configuration.

2. In a spraying device of the class described,

a nozzle having centrally disposed concentric liquid and compressed air orifices for the discharge of a spray of atomized liquid material, said nozzle also having a supplemental annular orifice formed therein laterally of said first named orifices for the discharge of a hollow jet of spray modifying air.

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 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 point spaced from the face of the nozzle, in order toy modify the cross sectional configuration of the spray.

4. 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 a plurality of concentric orifices formed therein upon each side of said axially disposed means and directed so as to discharge concentric substantially tubuular jets of air to impingeupon opposite sides of said spray at a point spaced from the face of the nozzle, in order to modify the cross sectional configuration of the spray.

5. In a spraying device of the class described, a nozzle comprising, in combination, means provided axially thereof for discharging an atc'nized liquid spray, said nozzle also having a plurality of concentric annular orifices formed therein upon each side of said axially disposed means and directed so as to discharge concentric substantially tubular jets of air 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 configuration of the spray.

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 a plurality of concentric circular and annular orifices formed therein upon each side of said axially disposed means and directed so as to discharge concentric substantially tubular jets of air 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 configuration of the spray.

7. In a spraying device of the class described, a nozzle having centrally disposed concentric liquid and compressed air orifices for the discharge of a spray of atomized liquid material, certain of said orifices having a serrated margin for affecting the configuration, degree of atomization, and velocity of the marginal portions of the spray, said nozzle also having supplemental annular orifices formed therein laterally of said first named orifices for discharging hollow tubular jets of air against said spray to further affect the atomization and cross sectional configuration of said spray.

8. In a spraying device of the class described, a nozzle having centrally disposed concentric liquid and compressedair orifices for the discharge of a spray of atomized liquid material, the outer margin of the air orifice being provided with a multiplicity of serrations for affecting degree of atomization and the velocity of the marginal portions of the spray, there being a suflicient number of such serratons that the margin of said spray is roughened without altering the general circular configuration thereof.

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

nozzle having a central liquid orice, a substantially annular aspirating air orice concentric with said liquid orice, and laterally positioned supplemental air orifices directed so as to discharge converging spray modifying jets of air toward the prolonged axis of said first named orifices, the margin of said aspirating air orioe being provided with a plurality of kerfs at intervals of less than 90 around is periphery, there being a suicient number of suchiserrations that the margin of said spray is roughened without altering the general circular configuration thereof.

10. In a spraying device of the class described, a nozzle having a central -liquid orifice, a substantially annular aspirating air oriice concentric with said liquid orice, and laterally positioned supplemental air orifices directed so as to discharge converging spray modifying jets of air toward the prolonged axis of said ilrst named orices, the margin of said aspirating air orice being provided with a multiplicity of substantially rectangular kerfs at short intervals around its periphery, there being a sufcient number of such serrations that the margin of said spray is roughened without altering the general circular conguration thereof.

11. In a spraying device of the class described, a nozzle having a central liquid orifice, a substantially annular aspirating air orifice concentric with said liquid orice, and laterally positioned supplemental air orices directed so as to discharge converging spray modifying jets of air toward the prolonged axis of said rst named orices, the margin of said aspirating air orice being provided with a multiplicity of substantially wedge shaped kerfs at frequent intervals around its periphery, there being a suillcient number of such serrations that the margin of said spray roughened without altering the general circular conguration thereof.

12. In a spraying device of the class described, a nozzle comprising, in combination, means disposed axially thereof for the projection of a spray of atomized liquid material, and means disposed upon said nozzle on each side of said axis for projecting tubular jets of spray modifying air upon said axial spray, said last named means each comprising a bore communicating with a source of compressed air, and a plug disposed in said bore and having an elongated portion of somewhat smaller diameter than that of said bore and spaced from the walls of the bore to provide an annular passageway for the projection of the tubular jet. l

13. In a spraying device of the class described, a nozzle comprising, in combination, means disposed axially thereof for the projection of a spray of atomized liquid material, and means disposed upon said nozzle on each side of said axis for projecting tubular jets of spray modifying air upon said axial spray, said last named means each comprising a. bore communicating with a. source of compressed air, and a removable plug disposed in said bore and having an elongated portion of somewhat smaller diameter than that of said bore and spaced from the walls of the bore to provide an annular passageway for the projection of the tubular jet.

14. In a spraying device of the class described, a nozzle comprising, in combination, means disposed axially thereof for the projection `of a spray of atomized liquid material, and means disposed upon said nozzle on each side of said axis for projecting tubular jets of spray modifying air upon said axial spray, said last named means each comprising a bore communicating with a source of compressed air, and a removable plug threaded into said bore and having an elongated portion of somewhat smaller diameter than that of said bore and spaced from the walls of the bore to provide an annular passageway for the projection of the tubular jet.

l5. In a spraying device of the class described. a nozzle comprising, in combination, means disposed axially thereof for the projection of a spray of atomized liquid material, and means disposed upon said nozzle on each side of said axis for projecting tubular jets of spray modifyingk air upon said axial spray, said last named means each comprising a recess communicating with a source of compressed air, a pin of somewhat smaller diameter than that of said recess disposed Within said recess, and means for centering said pin with respect to said recess, whereby there is provided an annular orifice for the projection of said tubular jet.

16. In a spraying device of the class described, a nozzle comprising, in combination, means disposed axially thereof for the projection of a spray of atomized liquid material, and means disposed upon said nozzle on` each side of said axis for projecting tubular jets of spray modifying air upon said axial spray, said last named means each comprising a recess communicating with a source of compressed air, a hollow tubular pin lof somewhat smaller diameter than that of said recess disposed within said recess, means for centering said pin with respect to said recess, and means for admitting a portion of said air supply to the interior of said pin, whereby combined circular and annular orifices are provided for the projecting of said supplemental jets.

17. In a spraying device of the class described, a nozzle comprising, in combination, means disposed axially thereof for the projection of a spray of atomized liquid material, and means disposed upon said nozzle on each side of said axis for projecting tubular jets of spray modifying air upon said axial spray, said last named means each comprising a recess communicating with a source of compressed air, a pin of somewhat smaller diameter than that of said recess disposed within said recess, a tubular member also disposed within said recess concentrically of said pin and spaced from both said pin and the wall of the recess, and means for supplying the interior of said tubular member with compressed air, whereby double tubular jets of spray modifying air may be projected from said nozzle.

18.A A nozzle for spray guns or the like comprising, in combination, a substantially annular base member adapted to be applied to and to cooperate with the liquid nozzle and body portion of the gun, said base member being provided with a transverse rectangular slot cut in its forward face for the reception of a complementary jet portion,a member comprising said jet portion and provided with a plurality of jet orifices and fitted'within said slot, passageways Within said last named member leading to said oriiice, passageways in said base member providing communication between said first named passageways and the body of the gun.

ALEXANDER F. JENmNS.