CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of U.S. Patent Application No. 13/588,288, filed August 17, 2012, which is incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates generally to liquid spray nozzle assemblies, and more particularly, to an improved spray nozzle assembly adapted for discharging full cone conical spray patterns.

BRIEF SUMMARY OF THE INVENTION

[0003] Presently, most spray nozzles that generate a conical spray discharge with liquid spray particles distributed throughout the spray pattern have an internal mix design wherein pressurized liquid and air streams intermix and pre-atomize the liquid in a mixing chamber internally within the spray nozzle. The pre-atomized liquid then is discharged from the nozzle through a plurality of circumferentially spaced discharge orifices with the multiplicity of discharging fine particle streams blending together to form a conical spray pattern. A disadvantage of such spray nozzle assemblies is that the individual discharging streams have a tendency to develop undesirable streaking which impedes uniform distribution and application of the liquid spray. Since the pressures of the liquid and air introduced into the internal mixing chamber must be substantially similar to prevent one from adversely affecting the other, the control of the discharging spray pattern also is limited. The atomized liquid also can set up within the internal mixing chamber and clog or impede operation, particularly when spraying more viscous liquids.

[0004] While external mix air atomizing spray nozzle assemblies are known in which a liquid flow stream is atomized by pressurized air at or immediately following discharge from a liquid discharge orifice of the nozzle, such spray nozzles have not been well suited for generating and spraying full cone spray patterns. Such external mix spray nozzles have been limited both in their ability to control spray particle distribution throughout the conical spray pattern and vary the angle of the conical discharge. OBJECTS AND SUMMARY OF THE INVENTION

[0005] It is an object of the invention is to provide an improved pressurized air assisted liquid spray nozzle assembly adapted for more effectively producing full cone spray patterns with uniform liquid particle distribution across the pattern.

[0006] Another object is to provide a spray nozzle assembly as characterized above which is operable for generating conical spray patterns with a wider range of angles.

[0007] A further object is to provide a spray nozzle assembly of the foregoing type which can be operated at a wide range of different air and liquid pressures for enhanced control of the spray angle and liquid particle distribution of the conical spray discharge.

[0008] Yet another object is to provide a full cone spray nozzle assembly of the above kind which is effective for spraying viscous liquids without undesirable clogging.

[0009] Another object is to provide such a spray nozzle assembly which is relatively simple in construction and lends itself to economical manufacture.

[0010] Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a longitudinal section of an illustrative pressurized air atomized liquid spray nozzle in accordance with the invention;

[0012] FIG. 2 is a vertical section taken in the plane of line 2-2 in FIG. 1 ;

[0013] FIG.3 is an exploded view of the illustrative spray nozzle assembly;

[0014] FIG. 4 is a side elevational view of an internal air guide of the illustrated spray nozzle assembly;

[0015] FIG. 5 is a top end view of the air guide shown in FIG. 4;

[0016] FIG. 6 is a vertical section of the air guide shown in FIG. 4; and

[0017] FIG. 7 is a bottom end view of the air guide shown in FIG. 4.

[0018] While the invention is susceptible of various modifications and alternative constructions, a certain illustrative embodiment thereof has been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0019] Referring now more particularly to the drawings, there is shown an illustrative pressurized air assisted liquid spray nozzle assembly 10 in accordance with the present invention. The spray nozzle assembly 10 in this case is mounted on a conventional spray gun or head 1 1 having a central liquid passage 12 connected to a pressurized liquid supply 14 and first and second air passages 15,16 disposed in circumferentially offset relation to each other for coupling to suitable pressurized air supplies 18,19.

[0020] The illustrated spray nozzle assembly 10 basically comprises an inner central liquid spray nozzle 20, an annular air guide or core 21 disposed in surrounding relation to a downstream end of the liquid spray nozzle 20, and a cup-shaped nozzle body or cap 22 disposed about the air guide 21. The liquid spray nozzle 20 has a central liquid passageway 24 having a downstream inwardly converging conical section 25 that communicates with a small diameter nozzling section 26 and liquid discharge orifice 28 defined by a forwardly extending nose portion 29 of the liquid spray nozzle 20. The liquid spray nozzle 20 in this case has relatively small diameter upstream and downstream end portions 30,31, respectively, with the upstream end portion 30 being disposed within a counter-bore of the head 1 1 and sealed by annular sealing ring 32. The downstream end portion 31 is formed with an inwardly converging conical section 34 from which the small diameter nose portion 29 extends. The illustrated liquid spray nozzle 20 has an enlarged diameter intermediate section 35 with a radially extending mounting and locating flange 36 positioned against an end-face of the head 1 1. An upstream end of the enlarged diameter central portion 35 is disposed within a second counter-bore of the head 1 1 and sealed by an annular sealing ring 38.

[0021] The nozzle body or cap 22 has an outer cylindrical side wall 40 and an end wall 41 formed has a central opening 42 coaxial with the liquid spray nozzle passageway 24 and discharge orifice 28. The cylindrical side wall 40 has an outwardly extending annular shoulder 44 adjacent an upstream end which is secured to the head 1 1 by inappropriate retention ring or the like.

[0022] In accordance with the illustrated embodiment, the air guide defines (1) a first plurality of air passages effective for directing pressurized atomizing air transversely to the solid liquid flow stream discharging from the liquid spray nozzle for pre-atomizing the liquid into fine liquid spray particles and (2) a second plurality of air passages for directing a plurality of shaping air streams tangentially to the discharging pre-atomized liquid for further atomizing the liquid and forming the liquid particles into a conical full cone spray pattern. The first plurality of air passages in this case are in the form of six circumferentially spaced passages 50 extending through the air guide in substantially parallel relation to the central liquid passageway 24. The first passages 50 have upstream ends which communicate with an annular manifold passage 51 defined by a counter-bore 52 in the upstream end of the air guide 21 and a downstream end wall 54 of the intermediate section 35 of the liquid spray nozzle 20, which in turn communicates though a plurality of circumferentially spaced longitudinal passageways 55 with an annual manifold passage 56 in the head 1 1 , which in turn receives pressurized air from the air passage 15.

[0023] The downstream ends of the first plurality of air guide passages 50 communicate with a transverse annual passageway 60 defined between a recessed end face 61 of the air guide 21 formed by a counter-bore in the air guide and the end wall 41 of the nozzle body or cap 22. The transverse annular passageway 60 directs pressured atomizing air into converging transverse impingement with the solid liquid flow stream discharging from the liquid spray nozzle discharge orifice 28. The recessed end face 61 of the air guide 21 formed by a counter-bore 63 in this case has a diameter sized to intersect downstream ends of the plurality of first air guide passages 50 so as to define a plurality of circumferentially spaced atomizing air discharge orifices 64 adjacent transversely oriented end faces 65 of the passages 50 for directing the atomizing air in a radially inward direction. The counter bore 63 that defines the discharge orifices 64 preferably has an outer diameter that intersects the ends of the first passages 50 at locations radially inwardly of their respective longitudinal axes so that the passages 50 communicate with the transverse annular passage 60 through corners on the radially inward sides of the end faces 65 of the passages 50. The air guide 21 in this case has a central forwardly extending and inwardly tapered nose portion 66 surrounding the nose portion 29 of the liquid spray nozzle 20 for channeling the transversely directed atomizing air streams in slightly downstream angled relation to the liquid discharging to the liquid spray nozzle 20.

[0024] In carrying out the illustrated embodiment, the air guide 21 defines a second plurality of air passages which direct a plurality of tangentially directed shaping air streams in surrounding relation to the atomized liquid discharging from the nozzle for further atomizing and forming the discharging liquid spray into a well-defined conical spray pattern. To this end, in the illustrated embodiment, the air guide 21 has an outer hexagonal configuration defined by six flat surfaces 71 which define a corresponding number of circumferentially spaced peripheral air passages 70 between the air guide 21 and the outer cylindrical wall 40 of the nozzle body 22. Comers 72 of the joining fiat surfaces 71 of the air guide 21 are rounded to facilitate close positioning against the inner surface of the cylindrical sidewall 40. The circumferentially spaced peripheral passages 70 in this case communicate with an air manifold chamber 74 that in turn communicates about the outer flange 36 of the liquid spray nozzle 20 with the pressurized air passage 16 in the head 1 1.

[0025] In keeping with this embodiment, an outer end face 75 of the air guide 21 and the nozzle body end wall 41 define a plurality of tangential passages 76 each communicating with a respective one of the peripheral passages 70 for directing pressurized shaping air streams tangentially about the atomized liquid discharging from the liquid spray nozzle 20 so as to both further atomize and create a whirling action that forms the discharging spray particles into a conical spray pattern. In this case, the end wall 75 of the air guide 21 is formed with tangentially directed grooves 76a which define the tangential air shaping passages 76 with the nozzle body end wall 41 against which the air cap abuts.

[0026] While the transverse atomizing air and tangential shaping air streams act upon the discharging liquid initially within the central aperture 42 of the air nozzle body 22, it has been found that the tangential shaping air, by its swirling direction, continues to shape and maintain the discharging spray into a well-defined conical spray pattern following discharge from the liquid spray nozzle. In the illustrated embodiment, the central nozzle body opening 42 terminates with an outwardly tapered chamfer 42a.

[0027] A unique feature of the pressurized air atomizing nozzle of the present invention with the combination of transverse atomizing and tangential shaping air discharge passages is the ability to maintain and control a full cone spray pattern with uniform liquid distribution across the pattern at a wide range of air and liquid pressure combinations. This is

accomplished by selectively impinging the solid liquid flow stream exiting the discharge orifice of the liquid spray nozzle with a plurality, in this case six, transversely directed pressurized air streams and simultaneously controlling and shaping the atomized particles by the plurality, again in this case six, tangential pressurized air streams. The transverse pressurized air streams atomize the liquid on impact and the tangential air streams rotate the atomized droplets to form a uniform and controlled full cone spray pattern. The combination of direct impact and tangential rotation of the liquid stream has been found to have important utility in atomizing many types of liquids with a wide range of viscosities. This is possible because most of the atomization takes place outside the liquid spray nozzle in a fashion similar external mix atomizing spray nozzles, and hence, can be used with even highly viscous liquids without clogging or material build-up that impairs spray performance.

[0028] While in the illustrated embodiment, the nozzle assembly includes six passages for both channeling and directing pressurized atomizing and shaping air, alternatively greater or lesser numbers of passages may be utilized for particular spray applications. Preferably, between four and eight passages in each instance are employed.

[0029] In keeping with a further feature of this embodiment, the transverse air atomizing passages and the tangential shaping pressurized air passages may be controlled individually for particular spray applications. To this end, an illustrated embodiment, a separately controlled pressurized air supply 19 is provided for the transverse atomizing air passages and a separately controlled pressurized air supply 18 for the tangential shaping air.

[0030] In the illustrated embodiment, the liquid spray nozzle nose 29 and a central opening in the air guide 21 define an annular discharge passage 80 which communicates with the annular manifold air chamber 54 by one or more passages 81 defined between the liquid spray nozzle 20 and a downstream internal chamber 82 of the air guide 21. The annular pressurized air stream discharging axially from the passage 80 facilitates outward direction of the discharging liquid spray particles and maintains the nozzle clear of undesirable material build-up. Alternatively, the liquid spray nozzle nose 29 may be tightly disposed within the central air guide opening so that the discharging spray is controlled entirely by the transverse and shaping pressurized airstreams.

[0031] From the foregoing, it can be seen that the pressurized air assisted liquid spray nozzle of the present invention is adapted for more effectively and versably producing full cone spray patterns with liquid particle distribution throughout the pattern. By individually varying the pressure of atomizing air and shaping air, the spray nozzle further is operable for generating a wide range of conical spray angles. The spray nozzle further is effective for spraying viscous liquids without performance impeding clogging. Yet, the spray nozzle assembly is relatively simple in construction and lends itself to economical manufacture.

[0032] It will be understated that the use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning

"including, but not limited to,") unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0033] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.