US3820722A - Aggregate spray gun - Google Patents

Abstract

A nozzle support structure and nozzle held thereby are designed for cooperation with an air chamber receiving pressurized air and a delivery tube from a container of an aggregate spray composition. The delivery tube extends into the support structure past the exit end opening of a reduced diameter passage and terminates in a free end spaced from the outlet orifice of the nozzle. A portion of this free end includes an external O-ring which blocks backward movement of the delivery tube when the Oring engages the exit end opening of the reduced diameter passage. The orifice of the nozzle is tapered and includes an entrance portion which limits the degree of forward movement of the delivery tube in the support structure and by making the position of the nozzle longitudinally adjustable on the support structure the distance between the exit end opening of the reduced diameter passage and the entrance portion of the nozzle orifice can be varied thereby limiting the amount of air that can bypass about the O-ring and mix with aggregate spray composition so that the splatter pattern of the spray can be controlled.

Description

United States Patent [191 Jett et al.

[111 3,820,722 June 28, 1974 AGGREGATE SPRAY GUN [76] Inventors; Howard V. Jett, 238 Los Angeles Ave., Moorpark, Calif. 93021; Joseph V. DeMarco, 165 W. Ripley St., Tarzana, Calif. 93010 [22] Filed: July 25, 1973 i [21 Appl. No.: 382,542

Related US. Application Data [63] Continuation-in-part of Ser. No. 254,899, May 19,

[52] US. Cl. 239/373, 239/355 [51] Int. Cl. B05b 7/24 [58] Field of Search 239/329, 331, 355, 360, 239/373 [56] References Cited UNITED STATES PATENTS 1,670,235 5/1928 Buchanan 239/255 X 2,923,481 2/1960 Pinke 239/355 X Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-John J. Love Attorney, Agent, or Firm-Pastoriza & Kelly [5 7] ABSTRACT A nozzle support structure and nozzle held thereby are designed for cooperation with an air chamber receiving pressurized air and a delivery tube from a container of an aggregate spray composition. The delivery tube extends into the support structure past the exit end opening of a reduced diameter passage and terminates in a free end spaced from the outlet orifice of the nozzle. A portion of this free end includes an external O-ring which blocks backward movement of the delivery tube when the O-ring engages the exit end opening of the reduced diameter passage. The orifice of the nozzle is tapered and includes an entrance portion which limits the degree of forward movement of the delivery tube in the support structure and by making the position of the nozzle longitudinally adjustable on the support structure the distance between the exit end opening of the reduced diameter passage and the entrance portion of the nozzle orifice can be varied thereby limiting the amount of air that can bypass about the O-ring and mix with aggregate spray composition so that the splatter pattern of the spray can be controlled.

5 Claims, 5 Drawing Figures PMENTEMuxze m4 3.820.722

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AGGREGATE SPRAY GUN This application is a continuation in part of our copending application, Ser. No. 254,899 filed 5-49-72 entitled Splatter Pattern Control For Spray Guns.

This invention relates generally to spray guns and more particularly, to a portable spray gun having an improved nozzle and nozzle support assembly for controlling the splatter pattern of an aggregate type spray composition ejected from the gun.

BACKGROUND OF THE INVENTION It is common practice in new building construction, using dry wall material for walls and ceiling to provide a textured finish by spraying a suitable composition onto the wall and ceiling surfaces. Normally, the texture material is forced through a hose by a motor powered pump. The material is broken up and mixed with air in a nozzle from an air compressor or other pressurized source. The mixture of air and textured material or spray composition is ejected out of the nozzlev onto the walls, the splatter pattern giving the surface a uniform look which helps hide imperfections. The texture coating also serves as a base coat for paint.

The usual spray equipment involved is somewhat bulky, usually including the mixture, pump and air compressor mounted on a flat bed truck. Gasoline engines are utilized to provide power for the pumps. Once all of the interior walls of a new construction have been sprayed, the equipment and the flat bed truck are removed. However, if small patches are missed or a wall should become damaged and require repair, it is normally a nuisance as'well as expensive to bring back the entire flat bed truck constituting the spray rig. It would be far preferable if there were developed a simple way of spraying such patches with a small hand unit.

Such a small portable easily usable type hand unit has been developed wherein a manually operable air compressor in conjunction with a small container holding a small quantity of the spray composition similar to a garden or insecticide spray system is utilized. Since the spray composition is normallythicker than the usual compositions employed with garden or insecticide type sprayers, the nozzle orifice has been made larger and the spray composition delivery tube hasbeen made somewhat larger. The critical factor, however, arises in attempting to control the splatter pattern of the ejected composition-air mixture from the nozzle on the wall surface. In making repairs, it is, of course, desirable to match the particular texture pattern initially provided on the wall. This pattern may vary from a relatively small grain appearance such as on an orange peel to a fairly large or "lumpy" appearance.

A control of the spray pattern from aportable hand spray unit can be accomplished by controlling the amount of air permitted to mix with the spray composition prior to ejection from the nozzle. Generally, the more air that mixes with the spray composition the finer will be the textured pattern or splatter pattern on the wall whereas the less air provided the more pronounced will be the texture on the wall. The delivery tube for the spray composition normally passes up from a container into the nozzle support head where it ejects material into the nozzle to mix with air passing from the hand operated compressor over the endof thedelivery tube also into the nozzle. By controlling the annular space between the outside of the delivery tube and the interior annular wall of the nozzle head structure, the amount of air permitted to mix with the composition can be varied. One such control takes the form of provi cling a reduced diameter opening in the nozzle support head through which the delivery tube passes. An enlargement on the free end of the delivery tube can then be caused to seat back against this reduced diameter opening thereby restricting the amount of air that can flow around the enlargement: into the nozzle itself. Usually a coiled spring is utilized to bias or urge the enlarged portion of the free end of the delivery tube against the annular shoulder or collar defined by the reduced diameter portion. This coiled spring may be sandwiched between the reduced diameter portion and the nozzle itself and thus by adjusting the longitudinal position of the nozzle on the end of the nozzle head support, the compression force of the spring against the enlargement which is seated against the reduced diameter opening can be varied and thereby affect the amount of air that can be bypassed about the enlargement.

The major problem with the foregoing arrangement is the fact that the spring constant of any spring varies with use and age so that the compression force varies. As a result, it is very difficult to provide a consistent splatter pattern for any particular setting of the nozzle. The situation is particularly serious when high viscosity or aggregate compositions are used.

BRIEF DESCRIPTION OF THE PRESENT INVENTION The present invention constitutes an improved portable hand spray device particularly useful for repairing small patches of walls wherein an extremely accurate control of the splatter pattern of a high viscosity or aggregate composition can be realized without the use of springs all to the end that a consistent result is attained even after prolonged use of the device.

More particularly, a nozzle is supported on a support structure on a portable spray gun which communicates with air and the free end of a spray composition delivery tube means but wherein no springs are incorporated and wherein an essentially straight line passage is provided. In this respect, the support structure includes a reduced diameter passage through which the free end of the delivery means extends and the nozzle includes a tapered orifice having an entrance portion spaced from the exit end of the reduced diameter passage. The free end of the delivery means in turn includes an enlargement sandwiched between the exit end of the reduced diameter passage and the entrance portion of the nozzle and has a limited degree of longitudinal travel back and forth. Threading means on the nozzle and support head are provided enabling adjustment of the longitudinal position of the nozzle itself, this adjustment in turn changing the spacing between the exit end of the reduced diameter passageand the entrance portion of the nozzle orifice so as to change the limit of longitudinal movement of the delivery means. By this arrangement, a controlled amount of air can pass about the enlargement of the delivery means to mix with spray composition from the free end of the delivery means in the nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention will be had by referring to the accompanying drawings in which:

FIG. 1 is an enlarged perspective view partly cutaway of the spray gun of this invention;

FIG. 2 is an enlarged fragmentary cross-section of the head support and nozzle assembly showing the nozzle in a first longitudinal position taken in the direction of the arrows 2-2 of FIG. 1;

FIG. 3 is a fragmentary view similar to FIG. 2 showing the nozzle in a second longitudinal position;

FIG. 4 is an exploded perspective fragmentary view of certain components of the assembly shown in FIG. 3; and

FIG. 5 is a fragmentary cross-section of the lower end of the delivery tube portion enclosed in the circular arrow 5 of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Referring first to FIG. 1, there is shown a spray gun including means for providing air under pressure in the form of a simple cylinder incorporating a piston head connected to a piston rod 11 terminating in a handle 12 for manual pumping. The forward end of the cylinder 10 includes an air chamber 13 communicating with a suitable opening in a cap 14 rigidly secured to the lower wall of the chamber 13 as at 15. A container 16 for an aggregate spray composition 17 is threadedly held by the cap 14 as shown. The spray composition is passed through the air chamber 13 from a delivery tube 18. Preferably this delivery tube is also of plastic and of a somewhat larger diameter than conventional type delivery tubes in order to handle the more viscous spray composition 17. 1

The forward portion of the air chamber 13 terminates in a nozzle support structure 19 for holding a nozzle 20 having an outlet orifice 21.

Referring now to the enlarged cross-section of FIG. 2, there is shown at the right hand portion the piston 22 connecting to the end of the piston rod 11. This piston may include a check valve in the form of a flap 23 for admitting air through internal passages 24 in the piston when the piston is drawn to the right and forcing air from the front of the piston through a second check valve comprised of an opening 25 in a partition wall 26 arranged to becovered by a flap 27. Any other suitable check valve arrangement may be provided, all that is required being the supply of air under pressure into the air chamber 13.

It will be noted that there is provided an opening 28 in the lower portion of this air chamber communicating with a corresponding size opening in the cap 14 for the container described in FIG. 1. It will also be clear that the delivery tube 18 connects to a rigid tubular section 29 extending up through the opening 28, this opening being large compared to the diameter of the tubular section 29 so that there is ample room for air in the chamber 13 to pass about the tubular section 29 into the container 16.

In accord with a feature of the invention the tubular section 29 has one end 30 inserted in the end of the plastic tubing 18 and its other free end 31 terminating in an enlarged means comprising an O-ring 32 and head 33 provided with grooves 34 defining air passages.

The nozzle support 19 defines a reduced diameter passage 35 having a diverging exit opening 36 provided with air channels 37. As shown, the free end 31 of the tubular section extends longitudinally through the reduced diameter passage 35. The O-ring 32 itself is sufficiently large and it will seat against the diverging exit end of the reduced diameter passage 36 to prevent complete retraction of the free end back into the air chamber 13.

The tapered outlet orifice 21 has an entrance portion 38 dimensioned to engage a front beveled face on the head 33 to limit forward movement of the tubular section longitudinally within the assembly.

The nozzle support structure 19 itself is provided with external threads 40 cooperating with internal threads 41 of the nozzle 20, this threaded coupling a'ssuring that the outlet orifice 21 will be in coaxial alignment with the tubular section free end 31. The degree of threading of the nozzle 20 on to the nozzle support 19 determines the distance between the exit end 36 of the reduced diameter passage 35 and the entrance portion 38 of the orifice 21. In the showing of FIG. 2, this distance is designated D1 and represents a position wherein the O-ring 32 is lightly seated against the di' verging exit end 36 of the reduced diameter passage 35. Because of the channels 37 formed in this diverging exit end, however, air can by-pass about the O-ring 32 and thence pass through the grooves 34 of the head 33 to mix with spray composition within the tapered noz zle orifice 21.

It should be noted in FIG. 2 that the nozzle 20 may be further threaded on the nozzle support 19 thereby actually forcing the O-ring gradually into an extremely tight engagement with the diverging exit opening 36 squeezing the O-ring into the channels 37 and thereby gradually blocking air as desired from passing about the O-ring. As shown, the exit end opening 36 includes an annular shoulder 36 which actually seats the major portion of the O-ring in a complete shut-off case. This arrangement prevents any tendency for the O-ring to become lodged or stuck in the channels or in the reduced diameter passage.

FIG. 3 shows the identical components of FIG. 2 of the nozzle assembly, the same numerals designating corresponding parts but wherein the nozzle 20 has been threaded to decrease the distance between the exit end opening and the entrance to the nozzle to thereby partially block the channels 37 as described. This decreased distance is designated D2. In the position of FIG. 3, it will be evident that less air can pass about the O-ring because of partial blockage of the air channels 37.

In the preferred embodiment, there are provided six channels 37 in the exit end portion 36 as clearly illustrated in FIG. 4. Correspondingly, there are provided six grooves 34 in the head 33 on the end of the tubular section 29. In so far as the spray composition itself which passes through the tubular section 29 is concerned, it will be evident that there is provided a smooth straight line passage for this composition from the tubular section 29 to the nozzle orifice 21. Air to be mixed with this composition, in turn, is easily and accurately controlled between a condition where maximum air is provided when the nozzle is in the threaded position illustrated in FIG. 2 to a position in which only a small amount of air is provided as when the 0-ring is urged against the exit end opening and partially into the channels as shown in FIG. 3. As mentioned, complete air blockage is possible by further threading of the nozzle to completely block the channels 37 the O-ring seating against the annular shoulder 36 at the exit end opening.

FIG. 5 is an enlarged cross section of the lower end of the delivery tube 18 wherein there is provided a smoothly flared insert 42 to avoid the presence of blunt abutments to aggregate particles feeding into the delivery tube. In further keeping with the concept of providing a smooth path for the spray composition, the connection point between the one end of the rigid tubular section 29 and the upper end of the plastic delivery tube portion 18 designated 30 in FIG. 5 is smoothly tapered so as to avoid the presence of facing abutments to the flow of composition. The provision of a smooth passageway is important in order to avoid clogging or packing of aggregate particles in the composition.

To further avoid clogging or packing. the dimensions of the nozzle orifice relative to the size of the aggregate particles isimportant. With reference to FIG. 1, let A represent the average diameter of an aggregate particle for the specific composition 17. Referring to FIGS. 3 and 4, let (1 denote the diameter of the outlet end of the tapered orifice 21 and let D represent the diameter of the inlet end of the orifice 21 at the junction with the entrance surface 38. Let L equal the length vof the tapered portion of the orifice 21. In FIG. 4, it will be noted that the inside diameter of the passage way in the section 29 and head 33 is D which corresponds precisely with the entrance diameter D of the orifice 21 thereby assuring the heretofore referred to smooth passageway.

With the foregoing dimensions in mind, the relative relationships there between may be expressed as follows:

OPERATION The operation of the spray gun of this invention will be evident from the foregoing description. Initially,

with the container 16 of FIG. 1 unthreaded from the cap 14, and the nozzle removed from the end of the support structure 19, the delivery tube section 29 may be urged forwardly to expose out of the end of the support structure 19 the enlarged means in the form of the O-ring 32 and head 33. The O-ring 32 prevents complete retraction of the delivery tube into the air chamber 13 as a consequence of its abutment against the di' verging exit opening 36 of the reduced diameter passage 35.

The nozzle 20 is now threaded onto the support structure 19 a given distance to adjust its spacing to a desired value shown in FIG. 2 or FIG. 3 or there between.

Spray composition 17 is then poured into the container 16 and the container then threaded to the cap 14. It will be noted that the delivery tube 18 which, as stated, is flexible and of plastic material is dimensioned to have its lower free end as close as possible to a lower corner of the container 16 so that maximum use of the composition 17 will result.

If now the piston 21 is hand pumped by the handle 12, compressed air will be forced into the air chamber 13. This increased air pressure will pass through the opening 28 and act on top of the spray composition 17 in the container16 urging the spray composition downwardly to force it up through the delivery tube 18. This same air pressure in the air chamber 13 will pass through the reduced diameter passage 35 and air channels 37 around the O-ring 32. The air passing around the 0-ring into the central portion of the nozzle 20 will pass through the grooves 3d and mix with the spray composition ejected from the head of the delivery tube, the mixture itself being ejected from the orifice 21 of the nozzle 20.

By adjusting the threaded position of the nozzle to thereby shift its longitudinal position on the support structure 19, the amount of air passing about the O-ring 32 can be precisely controlled. Thus, inward movement of the nozzle will urge the O-ring further against the exit end opening 36 to penetrate into the channels 37 and thus limit the amount of air that can bypass around the 0-ring. In this event, a fairly coarse splatter pattern would result since the major portion of the ejected spray constitutes the spray material itself with a mini mum amount of air mixed in. When the nozzle is threaded outwardly to increase the spacing such as at D1 in FIG. 2, the air channels 37 are opened up thereby permitting more air to bypass around the 0-ring and result in a finer splatter pattern.

An important feature of this invention constitutes provision of the diverging exit opening 36 with the channels 37 for passing air about the O-ring 32. It will be understood that the air pressure in air chamber 13 is applied both through the reduced diameter passage 35 and the opening 28 against the top of the spray composition ll7. If the spray composition 17 is relatively of high viscosity or includes large aggregates, the amount of pressure necessary to exert against this spray composition to force it up through the delivery tube is greatly increased over that amount of pressure necessary for a thinner or less viscous composition. Closing down of the channels provides this higher pressure against the spray composition.

In the case of thinner compositions, substantially less pressure is required to force the material through the delivery tube. Opening up the channels by positioning the 0-ring as shown in FIG. 2 permits more air to bypass about the O-ring thus reducing the pressure to the lesser value required to force the thinner material through the delivery tube at the desired speed.

Thus, by providing the channels 37 as described, the spray gun can readily be used with very fine or low viscosity compositions as well as with high viscosity or aggregate type compositions.

As mentioned heretofore, the degree of air passing about the III-ring can be adjusted with great accuracy by the threaded position of the nozzle, and thus when the O-ring is seated on the entrance end opening, control of air is realizable as described by threading of the nozzle to partially squeeze the O-ring into the channels thus diminishing the amount of air that can be bypassed about the tI-ring. The action is similar to a needle type valve which can be gradually closed to cut-off.

It will be evident from the foregoing, accordingly, that the present nozzle support and nozzle assembly de sign enables the gun to be used not only for coarse or high viscosity spray compositions but also to be used with very fine or thin compositions.

It will be understood, of course, that nozzles with different sized orifices can be provided, the particular orifice size being selected in accord with the particular aggregate particle size of the spray composition.

From the foregoing description, it will be evident that the present invention has provided a greatly improved portable type spray gun whose best application is patching up initially textured interior or exterior walls and ceilings with a pattern that precisely matches the texture of the initially applied coating It will also be evident that the spray gun while preferably designed for use with coarse or aggregate type spray compositions can readily be used with low viscosity or fine spray composition and that in both cases no springs whatever are involved so that long life and maintenance free operations are assured. Moreover, because of the described construction, disassembly and cleaning is very simple.

While the invention has been described with respect to the spraying of walls and ceilings, it should be understood that this spray gun can be utilized for spraying any types of composition wherein a control of the splatter pattern is desired.

What is claimed is:

1. In a spray gun including an air chamber, means for providing air under pressure into said chamber, a container for a spray composition to be sprayed from the gun having an open upper end communicating with said air chamber and a spray composition delivery means passing from the lower portion of the container through the open upper end thereof into the air chamber, an improved nozzle support structure and nozzle assembly communicating with the air chamber for controlling the splatter pattern of the spray composition, said improved assembly comprising, in combination:

a. a nozzle support structure defining an annular reduced diameter passage communicating with said air chamber and having a diverging exit end;

b. a rigid tubular section constituting part of said delivery means having one end passing through the air chamber into the container, and a free end extending longitudinally through the reduced diameter passage;

c. enlarged means on said free end dimensioned to engage the diverging exit end of the reduced diameter passage so that rearward movement of the said free end of the tubular section is blocked from complete retraction back into the air chamber, said enlarged means including a head having grooves therein; and,

d. a cylindrical nozzle having one end closed except for a central tapered outlet orifice of given size, said nozzle being threadedly receivable on the support structure in a position coaxial with the said free end of the tubular section and said reduced diameter passage, the tapered outlet orifice having an entrance portion adapted to engage said head on said tubular section to limit the forward movement thereof; whereby the longitudinal spacing between the exit end of said reduced diameter passage in the support structure and said entrance portion of the tapered outlet orifice in the nozzle is adjustable by varying the threaded longitudinal position of the nozzle on the support structure thereby enabling the amount of air which can pass between the enlarged means on the tubular section and the exit end of the reduced diameter passage to be controlled.

2. A spray gun according to claim 1, in which said diverging exit end of said reduced diameter passage includes air channels and wherein said enlargement means further includes an 0-ring behind said head, said O-n'ng engaging said diverging exit end such that further inward threading of the nozzle squeezes said O-ring into said air channels to provide for a precise control of the amount of air passing about the enlargement means.

3. A spray gun according to claim 2, in which the lower end of the delivery tube includes a flared insert to provide a smooth entrance passage for aggregate particles into said delivery tube.

4. A spray gun according to claim 1, in which if A is the average diameter of an aggregate particle in said spray composition, (1 is the inside diameter of the exit end of said tapered outlet orifice, D is the inside diame ter of the entrance end of said tapered outlet orifice, and L is the length of said tapered outlet orifice, then the inside diameter of said rigid tubular section is equal to D and the following relationships exist:

2A d 5A D/2 L 2D 5. A spray gun according to claim 2, in which said diverging exit end of said passage includes an annular shoulder for seating the major portion of said O-ring when the nozzle is threaded inwardly a sufficient extent to close off the air channels completely, said shoulders preventing any tendency of the O-ring to become stuck in the air channels or in the reduced diameter passage. i= =k

Claims (5)

1. In a spray gun including an air chamber, means for providing air under pressure into said chamber, a container for a spray composition to be sprayed from the gun having an open upper end communicating with said air chamber and a spray composition delivery means passing from the lower portion of the container through the open upper end thereof into the air chamber, an improved nozzle support structure and nozzle assembly communicating with the air chamber for controlling the splatter pattern of the spray composition, said improved assembly comprising, in combination: a. a nozzle support structure defining an annular reduced diameter passage communicating with said air chamber and having a diverging exit end; b. a rigid tubular section constituting part of said delivery means having one end passing through the air chamber into the container, and a free end extending longitudinally through the reduced diameter passage; c. enlarged means on said free end dimensioned to engage the diverging exit end of the reduced diameter passage so that rearward movement of the said free end of the tubular section is blocked from complete retraction back into the air chamber, said enlarged means incLuding a head having grooves therein; and, d. a cylindrical nozzle having one end closed except for a central tapered outlet orifice of given size, said nozzle being threadedly receivable on the support structure in a position coaxial with the said free end of the tubular section and said reduced diameter passage, the tapered outlet orifice having an entrance portion adapted to engage said head on said tubular section to limit the forward movement thereof; whereby the longitudinal spacing between the exit end of said reduced diameter passage in the support structure and said entrance portion of the tapered outlet orifice in the nozzle is adjustable by varying the threaded longitudinal position of the nozzle on the support structure thereby enabling the amount of air which can pass between the enlarged means on the tubular section and the exit end of the reduced diameter passage to be controlled.

2. A spray gun according to claim 1, in which said diverging exit end of said reduced diameter passage includes air channels and wherein said enlargement means further includes an 0-ring behind said head, said 0-ring engaging said diverging exit end such that further inward threading of the nozzle squeezes said 0-ring into said air channels to provide for a precise control of the amount of air passing about the enlargement means.

3. A spray gun according to claim 2, in which the lower end of the delivery tube includes a flared insert to provide a smooth entrance passage for aggregate particles into said delivery tube.

4. A spray gun according to claim 1, in which if A is the average diameter of an aggregate particle in said spray composition, d is the inside diameter of the exit end of said tapered outlet orifice, D is the inside diameter of the entrance end of said tapered outlet orifice, and L is the length of said tapered outlet orifice, then the inside diameter of said rigid tubular section is equal to D and the following relationships exist: 2A < or = d < or = 5A d < or = L < or = 8d d< D < or = 5d D/2 < or = L < or = 2D

5. A spray gun according to claim 2, in which said diverging exit end of said passage includes an annular shoulder for seating the major portion of said 0-ring when the nozzle is threaded inwardly a sufficient extent to close off the air channels completely, said shoulders preventing any tendency of the 0-ring to become stuck in the air channels or in the reduced diameter passage.

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