Liquid spray gun, spray gun platform, and spray head assembly

Abstract

Liquid spray gun platforms, spray head assemblies and liquid spray guns including one or both of the spray gun platforms and the spray head assemblies are described.

Claims

1. A disposable, releasably attachable gravity-fed spray gun spray head assembly comprising a liquid port (94) for direct connection to a gravity-fed spray gun paint reservoir; a liquid nozzle opening (92) for spraying a liquid; a liquid inlet passage (93) in fluid communication with a liquid passageway (91), the liquid inlet passage and the liquid passageway fluidly connecting the liquid port (94) to the liquid nozzle opening (92); a barrel frame comprising a connection tab to assist in connection of the spray head assembly to a gravity-fed spray gun platform, wherein the connection tab comprises a lever element (130) comprising a projection (136) extending away from an interior of the barrel frame, wherein the lever element comprises a post (139) extending outwardly from the lever element to provide a user to place a finger to deflect the lever element to attach or detach the spray head assembly to or from a gravity-fed spray gun platform.

2. The spray head assembly of claim 1 wherein the barrel frame (120) comprises an inlet end edge (121) forming a closed perimeter at a barrel inlet.

3. The spray head assembly of claim 2 comprising a gasket (111) on the inlet edge (121).

4. The spray head assembly of claim 1 comprising a barrel inlet, wherein the barrel inlet comprises a fan control barrel passage (87) and a fan control air passage gasket (112) to provide a seal between the fan control barrel passage (87) and a fan control air passage outlet in a gravity-fed spray gun platform.

5. The spray head assembly of claim 4 comprising a gasket (111) on the inlet edge (121), wherein the gasket (111) and the fan control air passage gasket (112) form a unitary seal assembly (110).

6. The spray head assembly of claim 5 wherein the unitary seal assembly (110) comprises an elastomeric plastic material.

7. The spray head assembly of claim 1 wherein the barrel frame (120) comprises an aperture (122) formed in a barrel wall (72), wherein the connection tab is at least partially bounded by the aperture.

8. The spray head assembly of claim 1 wherein the connection tab is located within an aperture (122).

9. The spray head assembly of claim 8 wherein the lever element (130) is cantilevered within the aperture (122) such that the lever element comprises a first end connected to the barrel wall.

10. The spray head assembly of claim 1 wherein the lever element comprises a free end (131) that is not connected to the barrel wall.

11. The spray head assembly of claim 1 further comprising an aperture (122) and a seal element (114) provided to close the aperture 122 around the lever element (130).

12. The spray head assembly of claim 11 comprising a gasket (111) on an inlet edge (121), wherein the gasket (111) and a seal element (114) form a unitary seal assembly (110).

13. The spray head assembly of claim 12 comprising a barrel inlet, wherein the barrel inlet comprises a fan control barrel passage (87) and a fan control air passage gasket (112) to provide a seal between the fan control barrel passage (87) and a fan control air passage outlet in a gravity-fed spray gun platform, wherein the fan control air passage gasket (112), the gasket (111), the seal element (114) form a unitary seal assembly (110).

14. The spray head assembly of claim 11 wherein the unitary seal assembly (110) comprises an elastomeric plastic material.

15. The spray head assembly of claim 1 wherein the projection is sized and positioned to fit within an appropriate structure on a gravity-fed spray gun platform.

16. The spray head assembly of claim 1 wherein the lever element (130) comprises a projection (136) extending away from an interior of the barrel frame, wherein deflection of the post (139) deflects the projection.

17. The spray head assembly of claim 1 wherein the liquid inlet passage is configured such that a liquid drawn through the liquid port in use is delivered to the nozzle in the liquid spray head assembly without passing through the gravity fed spray gun platform.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an exploded perspective view of one embodiment of a liquid spray gun as described herein.

(2) FIG. 2 is a perspective view of the liquid spray gun of FIG. 1 after assembly.

(3) FIG. 3A is an exploded perspective view of the liquid spray gun platform of FIG. 1 taken from a left side of the platform.

(4) FIG. 3B is an exploded opposing perspective view of the liquid spray gun platform of FIG. 1 taken from the right side of the platform.

(5) FIG. 4 depicts the volumes of the air supply manifold, the center air passage, and the fan control air passage within the liquid spray gun platform of FIG. 1.

(6) FIG. 5 is a top plan view of the liquid spray gun platform depicted in FIG. 1.

(7) FIG. 6 is a cross-sectional view of the liquid spray gun platform of FIGS. 1 and 2 taken along line 6-6 in FIG. 5.

(8) FIG. 7 is an exploded side view of one embodiment of a spray head assembly as described herein.

(9) FIG. 8 is a rear view of the barrel taken from the line 8-8 in FIG. 7.

(10) FIG. 9 is a front view of the barrel taken from line 9-9 in FIG. 7.

(11) FIG. 10 is a vertical cross-sectional view of the spray head assembly of FIG. 7 as assembled.

(12) FIG. 11 is a cross-sectional view of the air cap of the spray head assembly of FIG. 10 removed from the barrel.

(13) FIG. 12 depicts the volumes of the center air chamber and the fan control air chamber in the spray head assembly as assembled in FIG. 5.

(14) FIG. 13 is an exploded perspective view of one embodiment of a barrel frame and seal element used to construct a barrel used in a spray head assembly as described herein.

(15) FIG. 14 is a side view of the barrel frame of FIG. 13.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(16) In the following detailed description of illustrative embodiments of the liquid spray guns and components, reference is made to the accompanying figures of the drawing which form a part hereof, and in which are shown, by way of illustration, specific embodiments in which the liquid spray guns and components described herein may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

(17) One embodiment of a liquid spray gun as described herein is depicted in the exploded view of FIG. 1. The same liquid spray gun is depicted as assembled in FIG. 2. The liquid spray gun includes a variety of components including a liquid spray gun platform 10 and a spray head assembly 60 that is preferably releasably attached to the liquid spray gun platform 10 at a barrel interface 11. The spray head assembly 60 is preferably releasably attached to the platform 10 and provides features that control movement of both the liquid to be sprayed and the air used to spray the liquid as described herein. Preferably, the spray head assembly 60 is disposable and can be thrown away after use (although in some instances it may be reused). If disposed after use, cleaning of the spray head assembly can be avoided and the spray gun can be changed over to dispense another liquid by attaching a different spray head assembly connected to the same or a different liquid container.

(18) Connection of the spray head assembly 60 to barrel interface 11 of the spray gun platform 10 may be achieved by any suitable technique. For example, connection structures on the spray head assembly 60 may cooperate (e.g., mechanically interlock) with the openings 11a and 11b at the barrel interface 11 to retain the spray head assembly 60 on the spray gun platform 10 as described herein. Many other connection techniques and/or structures may be used in place of those described herein, e.g., a bayonet type connection that facilitates rapid connection/disconnection of the spray head assembly with a simple push or push-twist action, clamps, threaded connections, etc.

(19) The spray gun platform 10 may also include an optional handle 19 that fits over the stem portion 13 of the frame 12. The handle 19 may, in some embodiments, be custom designed according to the operator's preference, including custom fitting by means of a thermosetting resin. Custom-fitted handles may reduce operator fatigue by allowing for a grip surface that can be custom molded to fit the hand of an individual user. The handle may be formed from a thermosetting resin and an intended user of the spray gun can grasp the handle while the resin is in an unhardened condition to impart a contoured surface to the handle that is customized for the hand of that user. In those embodiments in which the handle 19 is detachable from the frame 12, similar handles can be readily prepared for other users of the spray gun which allows a single spray gun to be accompanied by an array of handles, each of which has a grip surface that has been custom-fitted to the hand of a different intended user.

(20) The platform 10 includes a frame 12, a left cover plate 14, a right cover plate 16, and a barrel interface plate 18. The cover plates 14 and 16 and the barrel interface plate 18 are depicted as attached to the frame 12 in FIGS. 1 and 2, but detached from the frame 12 in FIGS. 3A and 3B. The various components may be connected to each other by any suitable technique or combination of techniques. Examples of some potentially suitable connection techniques may include, e.g., welding (thermal, chemical, etc.), adhesives (epoxies, etc.), mechanical fasteners, etc. In some embodiments, the frame 12, cover plates 14 and 16, and barrel interface plate 18 are all constructed of one or more plastics that are amenable to thermal welding such as, e.g., ultrasonic welding.

(21) Although the platform 10 may preferably be constructed of plastic materials, the spray gun platforms described herein may be constructed of any suitable material that can be molded, cast, etc. to form the features described herein. Examples of some potentially suitable materials may include, e.g., metals, metal alloys, plastics (e.g., polycarbonates, nylons (e.g., amorphous nylons), polypropylenes, etc.), and others. If plastic materials are used to construct the platforms, the plastic material may include any suitable additives, fillers, etc. Selection of the materials used in the platforms described herein may preferably be based at least in part on the compatibility of the selected materials with the materials to be sprayed (e.g., solvent resistance and other characteristics may need to be considered when selecting the materials used to construct the platforms).

(22) The spray gun platform 10, as assembled, defines a variety of cavities that, taken together, form the passages that deliver air to the spray head assembly. FIG. 4 depicts the cavities/air passages formed in the spray gun platform 10 with the surrounding structure of the platform 10 removed for clarity. Among the cavities/passages formed in the spray gun platform 10 are an air supply manifold 20, a fan control air passage 30, and a center air passage 40.

(23) The air supply manifold 20 can be seen in the cross-sectional view of FIG. 6 which is taken along line 6-6 in FIG. 5. The air supply manifold 20 includes a terminal portion 21 to which the fan control air passage 30 and the center air passage 40 connect. Referring to FIG. 1, the air supply manifold 20 includes an inlet port 22 that may include a fitting 24 such that the air supply manifold 20 can be connected to an air source (not shown) that supplies air to the air supply manifold 20 at greater than atmospheric pressure.

(24) The cross-sectional view of FIG. 6 also depicts the needle passage 56 formed through the frame 12 to allow the needle 52 (see FIG. 1) to pass into a spray head assembly attached to the barrel interface

(25) The air supply manifold 20 is in fluid communication with the fan control air passage 30 and the center air passage 40 within the spray gun platform 10 so that air flowing into the air supply manifold 20 can be distributed to the fan control air passage 30 and the center air passage 40. Control over the air distribution from the air supply manifold 20 to the fan control air passage 30 may be accomplished by any suitable structures.

(26) Referring to FIGS. 1 and 2, control over both air flow and liquid flow through the liquid spray gun is, in the depicted embodiment, provided by a trigger 50 that is pivotally engaged to the spray gun platform 10 by a retaining pin 51a and clip 51b (although any other suitable connection mechanism could be used). A needle 52 extends through the spray head assembly 60 in a manner similar to that described in, e.g., U.S. Pat. No. 7,032,839. The trigger 50 is preferably biased to the inoperative position in which needle 52 closes the liquid nozzle opening in the spray head assembly 60 and also closes the air supply valve 54. In the depicted embodiment, the biasing force is provided by a coil spring 55, although other biasing mechanisms may be used.

(27) When the trigger 50 is depressed, needle 52 is retracted to a position in which the tapered front end 52a allows liquid to flow through liquid nozzle opening in the spray head assembly 60. At the same time, air supply valve 54 also opens to deliver air to the spray head assembly 60 from the air supply manifold 20. Air and liquid flow may be further controlled by a fan control air regulator assembly 32 which controls air delivered to the fan control air passage 30 from the air supply manifold 20 and center air regulator assembly 42 which controls air delivered to the center air passage 40 from the air supply manifold 20. In particular, the regulator assembly 42 controls the center air/liquid stream emanating from the spray head assembly, and regulator assembly 32 controls air flow to air horns of the spray head assembly 60 to adjust the spray pattern geometry. In some embodiments, however, it should be understood that adjustment of the center air regulator 42 may affect air flow through the fan control regulator assembly 32.

(28) The fan control air passage 30 of the spray gun platform 10 includes a first portion 33 that is in fluid communication with the air supply manifold 20 at location 26 (see, e.g., FIG. 4). The first portion 33 of the fan control air passage 30 leads to a second portion 34, followed by a third portion 35 and a fourth portion 36. The fourth portion 36 is located behind the barrel interface plate 18 of the spray gun platform 10 (see, e.g., FIG. 3A). In the depicted embodiment, the second portion 34 of the fan control air passage 30 provides space for the regulator assembly 32. Air flowing through the fan control air passage 30 thus passes from the air supply manifold 20 into and through the different portions of the fan control air passage 30 until it exits the fan control air passage 30 through fan control air passage outlet 37 formed in the barrel interface plate 18.

(29) The fan control air passage 30 of the spray gun platform 10 is defined, in the depicted embodiment, by the platform frame 12, the left cover plate 14, and the barrel interface plate 18 when those components are attached to each other. It may be preferred that the left cover plate 14 include one or more features designed to mate with one or more cavities in the frame 12 to form the various portions of the fan control air passage 30. For example, the cover plate 14 may include raised rib 33a (see FIG. 3B) that, in combination with the cavity 33b (see FIG. 3A), defines the first portion 33 of the fan control air passage 30. The fan control air passage 30 then passes through the frame 12 until it reaches the cavity 34b formed in the frame 12. The cover plate 14 also includes rib 34a (see FIG. 3B) that, in combination with the cavity 34b (see FIG. 3A) defines the second portion 34 of the fan control air passage 30. The ribs 33a and 34a may preferably be provided in the form of closed geometric figures and sealed around the edges of their respective cavities 33b and 34b to form the portions 33 and 34 of the fan control air passage 30. The sealing may be accomplished by any suitable technique or combination of techniques, e.g., welding (thermal, chemical, etc.), adhesives (epoxies, etc.), mechanical fasteners, etc.

(30) The center air passage 40 of the spray gun platform 10 includes a first portion 43 that is in fluid communication with terminal portion 21 of the air supply manifold 20 at location 27 (see, e.g., FIG. 4). The first portion 43 of the center air passage 40 leads to a second portion 44. The second portion 44 of the center air passage 40 is located behind the barrel interface plate 18 of the spray gun platform 10 (see, e.g., FIG. 3A). Air flowing through the center air passage 40 thus passes from the air supply manifold 20 into and through the portions of the center air passage 40 until it exits the center air passage 40 through center air passage outlet 47 formed in the barrel interface plate 18.

(31) The center air passage 40 of the spray gun platform 10 is defined, in the depicted embodiment, by the platform frame 12, the right cover plate 16, and the barrel interface plate 18 when those components are attached to each other. It may be preferred that the right cover plate 16 include one or more features designed to mate with one or more cavities in the frame 12 to form the various portions of the center air passage 40. For example, the cover plate 16 may include raised rib 43a (see FIG. 3A) that, in combination with the cavity 43b (see FIG. 3B), defines the first portion 43 of the center air passage 40. The rib 43a may preferably be provided in the form of a closed geometric figure that is sealed around the edges of cavity 43b to form the portion 43 of the center air passage 40. The sealing may be accomplished by any suitable technique or combination of techniques, e.g., welding (thermal, chemical, etc.), adhesives (epoxies, etc.), mechanical fasteners, etc.

(32) If welding (e.g., ultrasonic welding) is used to attach the left cover plate 14 to the frame 12 along the raised ribs 33a and 34a, one or both of the connections between the frame 12 and the raised ribs 33a and 34a may be characterized as defining a fan control air passage weld line, wherein the fan control air passage weld line forms a closed geometric figure between the left cover plate 14 and the frame 12. Similarly, if welding (e.g., ultrasonic welding) is used to attach the right cover plate 16 to the frame 12 along the raised rib 43a, the connection between the frame 12 and the raised rib 43a may be characterized as defining a center air passage weld line, wherein the center air passage weld line forms a closed geometric figure between the right cover plate 16 and the frame 12. The use of weld lines to seal the passages in the spray gun platform may provide advantages over other sealing techniques such as, e.g., gaskets, etc. which may further improve the airflow performance of the spray gun platform 10.

(33) Although the depicted embodiment of spray gun platform 10 includes a frame 12 and two cover plates 14 and 16, in other embodiments including a frame and cover plate construction, the spray gun platform may include only a single cover plate to define one or more of the passages in combination with the frame. In still other embodiments, the frame may be combined with three or more cover plates to complete the spray gun platform. In still other embodiments, the frame may be constructed in one or more parts such that no cover plates are needed to complete the spray gun platform.

(34) As discussed herein, the spray gun platform 10 may provide advantages over conventional spray gun platforms. Some of the potential advantages may be provided by molding the frame 12 of the spray gun platform 10 from a plastic material, such that the frame 12 is provided as a one piece, completely integral body with cavities formed as needed to define the various air passages through the platform 10. The molding process may provide the opportunity to reduce sharp edges and other features along the passages that may adversely affect fluid flow through the passages. Molding the frame 12 may also present an opportunity to reduce or eliminate secondary machining operations while also providing interior air passage surfaces that are smoother and more conducive to fluid flow through the platform.

(35) Another feature of the spray gun platform as depicted in FIGS. 1-6 is significantly increased dimensions for the air passages formed in the platform 10 as compared to conventional spray gun platforms. Referring to FIG. 4, for example, the platform 10 may include an air supply manifold 20 that has a volume of 0.536 in.sup.3 (about 8.8 cubic centimeters (cc)), a fan control air passage 30 that has a volume of 0.258 in.sup.3 (about 4.2 cc), and a center air passage 40 that has a volume of 0.154 in.sup.3 (about 2.5 cc).

(36) Although the actual volumes of the different features in the spray gun platform 10 may vary in different embodiments, the volumes of the features in the platform 10 may be characterized relative to each other. For example, in some embodiments, the fan control air passage 30 comprises a volume that is larger than a volume of the center air passage 40. In some embodiments, the volume of the fan control air passage 30 is 120% or more of the volume of the center air passage 40. In other embodiments, the volume of the fan control air passage 30 is 150% or more of the volume of the center air passage 40.

(37) The spray gun platform 10 may further be characterized in relative volumetric terms where the volume of the fan control air passage 30 and the volume of the center air passage 40 together are less than the volume of the air supply manifold 20. Although the combined volumes of the fan control air passage 30 and the center air passage 40 may be less than the volume of the air supply manifold 20, they may still have some lower limit. For example, in some embodiments, the volume of the fan control air passage 30 and the volume of the center air passage 40 together are 50% or more of the volume of the air supply manifold 20. In other embodiments, the volume of the fan control air passage 30 and the volume of the center air passage 40 together are 60% or more of the volume of the air supply manifold 20. In still other embodiments, the volume of the fan control air passage 30 and the volume of the center air passage 40 together are 70% or more of the volume of the air supply manifold 20.

(38) In addition to the volumetric characteristics described herein, the fan control air passage 30 may have an average cross-sectional area (where the average cross-sectional area is measured in a plane that is transverse to the air flow through the passage at the geometric center of the measuring location) that is the same as, larger than, or smaller than the average cross-sectional area of the center air passage 40.

(39) Having thus described the spray gun platform 10 and its various features, illustrative embodiments of the spray head assemblies 60 that may be used with the spray gun platforms 10 to provide a complete liquid spray gun can be described. Although the embodiment of the spray head assembly 60 described herein may be advantageously used with the spray gun platforms 10, other spray head assemblies may be substituted for those described herein to provide a complete liquid spray gun.

(40) As seen in FIGS. 1 and 7, the spray head assembly 60 may be provided in the form of a combination of two different components that are connected to each other to form the completed spray head assembly 60. More specifically, the spray head assembly 60 may include both a barrel 70 and an air cap 80. The barrel 70 and the air cap 80 of the spray head assembly 60 preferably combine to form cavities that deliver the center air and the fan control air in a substantially isolated manner through the spray head assembly.

(41) Referring to FIGS. 7-10, the barrel 70 includes a barrel inlet 71 that, in the depicted embodiment, preferably seals within the barrel interface 11 on the spray gun platform 10. The barrel inlet 71 is formed by the barrel wall 72 that in the depicted embodiment is largely in the form of a right circular cylinder (although other shapes could be used).

(42) The barrel 70 also includes features that define a liquid passageway 91 (see FIG. 10) that terminates in a liquid nozzle opening 92 through which the liquid to be sprayed exits the barrel 70. Liquid enters the liquid passageway 91 from the liquid inlet passage 93 that is fed through liquid port 94. The liquid passageway 91 through the barrel 70 is, perhaps, best seen in the cross-sectional view of FIG. 10 (although it should be understood that the air cap 80 has been rotated ninety degrees about the spray axis 100 in the cross-section view). The liquid passageway 91 defined in the barrel 70 is preferably largely isolated from the barrel chamber 73 formed within the barrel wall 72. The liquid passageway 91 is preferably sized to receive a needle 52 (see, e.g. FIG. 1) that is capable of closing the liquid nozzle opening 92 when advanced in the forward direction (to the left in the views depicted in FIGS. 1 and 10) and opening the liquid nozzle opening 92 when retracted in the rearward direction (to the right in FIGS. 1 and 10). The liquid passageway 91 may further include a needle housing extension 95 that extends rearward of the barrel 70 and may preferably fit within the needle passage 56 in the frame 12 (see, e.g., FIG. 6).

(43) The barrel wall 72 of the barrel 70 defines a barrel cavity 73 that surrounds the liquid passageway 91. The barrel cavity 73 receives air flowing out of the center air passage outlet 47 (see, e.g., FIG. 1) in the barrel interface 11 of the spray gun platform 10. As a result, the barrel cavity 73 defines a portion of a center air chamber within the spray head assembly 60. The center air entering the barrel cavity 73 passes through the barrel 70 and exits the barrel cavity 73 through openings 74 provided in the barrel 70.

(44) The barrel wall 72 is attached to the wall of the liquid passageway 91 by optional webs 77 that provide for additional structural integrity of the barrel 70, but that are not so large as to divide the barrel cavity 73 into independent cavities within the barrel 70. Two of the webs 77 are depicted in cross-section in FIG. 10 where it can be seen that they do not extend over the full length of the barrel cavity 73. As a result, the full volume of air in the barrel cavity 73 is available for delivery to the nozzle cavity 75 through the openings 74 as discussed herein.

(45) The openings 74 in the barrel 70 deliver the center air exiting the barrel cavity 73 to a nozzle cavity 75 formed between the air cap 80 and the front wall 76 of the barrel 70. Air entering the nozzle cavity 75 flows through the nozzle cavity 75 until it exits the nozzle cavity 75 though a center air outlet 62 formed between a nozzle aperture 82 in the air cap 80 and the liquid nozzle opening 92. The center air outlet 62 may preferably surround the liquid nozzle opening 92 such that the center air passing through the center air outlet 62 can form the liquid passing through the liquid nozzle opening 92 into a generally conical stream.

(46) Together, the barrel cavity 73 and the nozzle cavity 75 combine to form what can be characterized as the center air chamber of the spray head assembly 60. As described herein, the center air chamber essentially extends from the barrel inlet 71 to the center air outlet 62 of the spray head assembly 60. The center air outlet 62 is formed between the nozzle aperture 82 in the air cap 80 that surrounds the liquid nozzle opening 92. The center air chamber includes the nozzle cavity 75 located between the air cap 80 and the barrel 70. The center air chamber also includes the barrel cavity 73 located within the barrel 70 and the openings 74 formed through the front wall 76 of the barrel 70 through which air passes into the nozzle cavity 75 from the barrel cavity 73 for delivery to the center air outlet 62 during use of the spray head assembly 60. The nozzle cavity 75, the liquid nozzle opening 92, and the nozzle aperture 82 are shaped to direct the center air under greater than atmospheric pressure against liquid flowing out of the liquid nozzle opening 92 to propel the liquid away from the liquid nozzle opening 92 while shaping the liquid into a generally conical stream about an axis 100 extending through the liquid nozzle opening 92.

(47) The air cap 80 that is provided as a part of the spray head assembly 60 is depicted in FIGS. 1, 7, 10, and 11. The air cap 80 is preferably attached to the barrel 70 in a manner that allows for rotation of the air cap 80 about the axis 100 relative to the barrel 70. Examples of this rotation are demonstrated in the rotation of the air cap 80 over an arc of ninety degrees from its orientation in FIG. 7 to its orientation in the cross-sectional view of FIG. 10. Rotation of the air cap 80 may be used to change the orientation of the pattern of the atomized spray emitted from the spray head assembly 60 relative to the axis 100.

(48) In the depicted embodiment, the air cap 80 is retained in place over the front wall 76 of the barrel 70 by an interlocking arrangement of the annular recess 78 on the barrel 70 (see, e.g., FIGS. 7 and 10) and a complementary raised annular ridge 88 on the interior surface of the ring 81 of the air cap 80 (see, e.g., FIGS. 10 and 11). The junction between the ring 81 of the air cap 80 and the barrel 70 may preferably have a limited clearance such that leakage of fan control air through that junction is limited and/or to generate some friction to provide a resistive force to rotation of the air cap 80 about the axis 100 (although not so much force as to prevent rotation of the air cap 80 without tools). In some embodiments, a gasket, o-ring, or other seal element may be provided at the junction between the air cap 80 and the barrel 70 to provide additional control over leakage and/or rotational resistance.

(49) As discussed herein, the air cap 80 defines a nozzle cavity 75 at the front wall 76 of the barrel 70. In addition, the air cap 80 also defines cavities that, taken together, make up a portion of a fan control air chamber in the spray head assembly 60. Specifically, the ring portion 81 of the air cap 80 defines a ring cavity 84 located between the ring portion 81 of the air cap 80 and the barrel 70.

(50) The air cap also includes a pair of air horns 83a and 83b, each of which defines a horn cavity 85a and 85b (respectively) into which fan air enters from the ring cavity 84. Fan control air delivered into the air horn cavities 85a and 85b exits the cavities through fan control apertures 86a and 86b on the air horns 83a and 83b. The apertures 86a and 86b on the horns 83a and 83b are located on opposite sides of the axis 100 such that air flowing through the fan control air chamber under greater than atmospheric pressure flows against opposite sides of a stream of liquid formed by air flowing through the center air chamber. The forces exerted by the fan control air can be used to change the shape of the stream of liquid to form a desired spray pattern. The size, shape, orientation, and other features of the fan control apertures may be adjusted to achieve different fan control characteristics as described in, e.g., U.S. Pat. No. 7,201,336 B2 (Blette). In the depicted embodiment, the fan control apertures 86a and 86b are in the form of circular bores.

(51) Fan control air is delivered into the fan control air chamber in the spray head assembly 60 from the spray gun platform 10 through fan control air passage outlet 37 in the barrel interface 11 (see, e.g., FIG. 1). Isolation of the fan control air from the center air may be maintained as the fan control air passes through the barrel 70 by directing the fan control air through a fan control barrel passage 87 formed in the barrel 70 (see, e.g., FIG. 10). Air enters the fan control barrel passage 87 through an inlet end 87a from the fan control air passage outlet 37 of the platform 10 and is delivered to the ring cavity 84 for distribution to the air horn cavities 85a and 85b.

(52) Taken together, the fan control barrel passage 87, the ring cavity 84, and the air horn cavities 85a and 85b make up the fan control air chamber of the spray head assembly 60. FIG. 12 depicts the cavities/air passages formed in the spray head assembly 60 with the surrounding structure of the barrel 70 and the air cap 80 removed for clarity. Among the cavities/passages formed in the spray head assembly 60 are the barrel cavity 73 and the nozzle cavity 75 that form a part of the center air chamber as described herein. The volumes/cavities that form the openings 74 through which center air passes from the barrel cavity 73 into the nozzle cavity 75 are obscured by the nozzle cavity 75.

(53) Also depicted in FIG. 12 are the ring cavity 84 (shaded) and the air horn cavities 85a and 85b (also shaded) that form a portion of the fan control air chamber defined within the spray head assembly 60. The volume/cavity formed by the fan control barrel passage 87 (see, e.g., FIG. 10) is not depicted in FIG. 12 because it is obscured by the ring cavity 84 and the barrel cavity 73.

(54) Among the features of the spray head assembly 60 depicted the figures may be significantly increased dimensions for the air chambers formed in the spray head assembly as compared to conventional spray gun platforms. Referring to FIG. 12, for example, the spray head assembly 60 may include an center air chamber that has a volume of 1.059 in.sup.3 (about 17.4 cc) and a fan control air chamber that has a volume of 0.255 in.sup.3 (about 4.2 cc).

(55) Although the actual volumes of the different features in the spray head assembly 60 may vary in different embodiments, the volumes of the features in the spray head assembly 60 may be characterized relative to each other. For example, in some embodiments, the center air chamber of the spray head assembly 60 may have a volume that is greater than a volume of the fan control air chamber formed in the spray head assembly 60. In some embodiments, the center air chamber of the spray head assembly 60 may have a volume that is 200% or more of the volume of the fan control air chamber in the spray head assembly 60. In other embodiments, the center air chamber of the spray head assembly 60 may have a volume that is 300% or more of the volume of the fan control air chamber.

(56) In some embodiments, the volumes of the air flow features in a platform 10 to which the spray head assembly 60 is attached may be characterized together with the volumes of the features in the spray head assembly. The combined volumes may potentially offer some of the advantages in spray performance as discussed herein.

(57) For example, in a liquid spray gun (which includes a spray gun platform and a spray head assembly) the spray head assembly may have a center air chamber with a volume that is greater than the volume of the fan control air chamber in the spray head assembly. That volumetric relationship may, in some embodiments, be paired with a spray gun platform in which a fan control air passage has a volume that is larger than the volume of the center air passage through the spray gun platform.

(58) In other embodiments, a spray head assembly with a center air chamber with a volume that is greater than the volume of the fan control air chamber in the spray head assembly may be paired with a spray gun platform in which a fan control air passage and the fan control air chamber in the spray head assembly taken together have a combined volume that is less than a combined volume of the center air passage in the spray gun platform and the center air chamber in the spray head assembly.

(59) In still other embodiments, a spray head assembly with a center air chamber with a volume that is greater than the volume of the fan control air chamber in the spray head assembly may be paired with a spray gun platform in which the fan control air passage in the platform and the fan control air chamber in the spray head assembly taken together have a combined volume that is 75% or less of a combined volume of a center air passage in the spray gun platform and the center air chamber in the spray head assembly.

(60) In still other embodiments, a spray head assembly with a center air chamber with a volume that is greater than the volume of the fan control air chamber in the spray head assembly may be paired with a spray gun platform in which the fan control air passage in the platform and the fan control air chamber in the spray head assembly taken together have a combined volume that is 50% or less of a combined volume of a center air passage in the spray gun platform and the center air chamber in the spray head assembly.

(61) In still other embodiments, a spray head assembly with a center air chamber with a volume that is greater than the volume of the fan control air chamber in the spray head assembly may be paired with a spray gun platform in which the volume of a fan control air passage in the spray gun platform and the volume of a center air passage in the spray gun platform taken together are less than the volume of an air supply manifold in the spray gun platform.

(62) In some embodiments, the barrel 70 may include a gasket 111 that preferably extends about an inlet end edge 121 of a barrel frame 120 such that the barrel 70 can be sealed with a barrel interface 11 (see, e.g., FIGS. 1 and 13) when the barrel 70 is attached to a spray gun platform. The barrels 70 may also include a fan control air passage gasket 112 that provides a seal between the fan control barrel passage 87 and the fan control air passage outlet 37 in the barrel interface 11 (see, e.g., FIGS. 1 and 13).

(63) The barrels used in spray head assemblies as described herein may also include, as discussed above, structure to assist with connection and retention of the spray head assembly on a spray gun platform. In the embodiment of the barrel 70 as depicted in FIGS. 7, 13 and 14, the connection structure may take the form of a pair of connection tabs (although in some embodiments a single connection tab and associated lever element may potentially be used to make the connection).

(64) The connection tab structures may preferably be formed in a barrel frame 120 that includes an aperture 122 formed in the barrel wall 72. The aperture 122 may preferably be bounded on all sides of the barrel wall 72. In particular, it may be preferred (but not required) that the aperture 122 be bounded along the inlet edge 121 of the barrel frame 120 by a beam portion 123 spanning the opposing edges of the aperture 122, such that the inlet end edge 121 of the barrel frame 120 is continuous such that the inlet end edge 121 of the barrel frame 120 forms a closed perimeter at inlet end of the barrel 70. In other embodiments, the aperture 122 may extend to the inlet end 121 of the barrel frame 120 such that the inlet end edge 121 does not form a continuous edge or closed perimeter.

(65) A lever element 130 is located within the aperture 122. The lever element 130 may preferably be cantilevered within the aperture 122 such that the lever element 130 has a first end connected to the barrel wall 72/barrel frame 120 and a free end 131 that may not be connected to the beam portion 123 spanning the aperture 122 at the inlet end edge 121 of the barrel frame 120. The lever element 130 also includes a pair of side edges 133 extending from the first end towards the free end 131, wherein the lever element 130 may, in some embodiments, not be attached to the barrel wall 72/barrel frame 120 along the side edges 133.

(66) In the depicted embodiment, a seal element 114 is provided to close the aperture 122 around the lever element 130. The seal element 114 may also assist in biasing the lever elements 130 against inward movement during attachment or detachment of the spray head assemblies on a spray gun platform as described herein. (in addition to sealing barrel cavity 73 between the lever element 130 and the aperture 122 in which it is located).

(67) In some embodiments, the barrel frame 120 may be constructed (e.g., molded) from a first plastic and the seal element 114 may be constructed (e.g., molded) of a second plastic, and the second plastic of the seal element 114 may be attached to the first plastic of the barrel frame 120. In embodiments in which a seal element 114 is constructed of a material (e.g., plastic material) that is different than the material used for the barrel frame 120, attachment of the seal element 114 to the barrel frame 120 to close the aperture 122 may be performed by any suitable technique or combination of techniques, e.g., molding (e.g., insert molding, overmolding, etc.), adhesives (epoxies, etc.), mechanical fasteners, etc.

(68) Although the connection tabs may be described herein as including a lever element 130 located in an aperture 122 with a seal element 114 closing the aperture 122 around the lever element 130, in some embodiments, the seal element 114 and the barrel frame 120 (including the lever element 130) may all be constructed (e.g., molded) of a the same material with the seal element 114 being provided in the form of a thin web of material spanning the aperture 122 between the lever element 130 and the surround edges of the aperture 122. The seal element 114 may, by virtue of its thinner structure, provide the flexibility needed to displace the lever element 130 during attachment and removal of the barrel 70 as described herein. In some embodiments such as this, the seal element 114 may be integrally molded with the barrel frame 120 (e.g., molded in a single shot along with the barrel frame 120).

(69) In some embodiments, the lever elements 130 may include one or more struts 135 that connect a side edge 133 of the lever element 130 to an opposing edge of the aperture 122 in which the lever element 130 is located. In some embodiments, the lever elements 130 may be connected to the surrounding edges of the apertures 122 by a pair of struts 135, wherein each strut 135 connects one of the side edges 133 of the lever element 130 to an opposing edge of the aperture 122. The strut or struts 135 may preferably be located closer to the free end 131 of the lever element 130 than the first end of the lever element 130 (i.e., the end of the cantilevered element 130 that is attached to the barrel frame 120). The strut or struts 135 may, in some embodiments, be encased within the seal element 114 such that the strut is not exposed. The strut or struts 135 may potentially be useful to control deflection of the lever element 130 such that a seal element 110 is not unintentionally detached from the barrel frame 120.

(70) In some embodiments, the barrel frame 120 may be constructed of a first plastic and the seal element 111 may be constructed of a second plastic that is not the same as the first plastic. In some embodiments, the second plastic may be more flexible than the first plastic, e.g., the second plastic may be described as a more elastomeric material as compared to the first plastic used to construct the barrel frame. In some embodiments, the barrel frame 120 may be constructed of, e.g., polypropylene while the seal element is constructed of a thermoplastic elastomer (e.g., SANTOPRENE, etc.). In other embodiments, the seal elements 114 may preferably be constructed of elastomeric plastics such as, e.g., thermoplastic elastomers, thermoplastic urethanes, etc., although other materials may be used if they provide an adequate seal. Another factor that may be used in selecting materials for the barrel frame and seal elements may include the compatibility of the materials in a 2-shot molding process or other manufacturing process used to construct the barrels as described herein. Also, although the barrel frame may be constructed of one or more plastics, in some embodiments, the barrel frame could be constructed of other materials, e.g., metals, metal alloys, etc.

(71) In some embodiments that include a seal element 114 that is constructed of a material that is different than that used to construct the barrel frame 120 and where the seal element 114 is constructed of an elastomeric plastic that provides sealing capabilities, the seal element(s) 114 may be molded in the same shot as other sealing features on the barrel frame 120. In particular, FIG. 13 provides one example of such a construction in which the gasket 111 on the inlet end edge 121 of the barrel frame 120, the seal elements 114, and the fan control air passage gasket 112 are all molded from a single shot of an elastomeric plastic material. In such an embodiment, the sealing features taken together, may form a unitary seal assembly 110.

(72) The lever element 130 of the connection tab also preferably includes a projection 136, wherein the projection 136 extends away from an interior of the barrel frame 120 (see, e.g., FIGS. 8 and 13). The projections 136 may preferably be sized and positioned to fit within the openings 11a and 11b or other appropriate structures formed in the spray gun platform 10 such that the openings 11a and 11b and projections 136 cooperate (e.g., mechanically interlock).

(73) The embodiments of the lever elements 130 depicted in connection with the spray head assemblies described herein may also include posts 139 that also extend outwardly from the lever elements to provide a convenient location for a user to place his or her fingers to deflect the lever element 130 and its attached projection 136 inward during attachment or detachment of the spray head assemblies on a spray gun platform as described herein.

(74) The liquid spray guns, spray gun platforms, and spray head assemblies described herein may be used in spray gun systems that may be commonly referred to as gravity-fed spray guns (where the liquid to be sprayed is fed under gravity to the spray head assembly), siphon-fed spray guns (where the liquid to be sprayed is siphoned into the spray head assembly from a reservoir), and/or pressure-fed spray guns (where the liquid to be sprayed is fed under pressure from the reservoir into the spray head assembly). Further, auxiliary components that may be used in connection with the spray guns, spray gun platforms, and spray head assemblies discussed herein, and their respective methods of use, may be described in more detail in, e.g., U.S. Pat. No. 6,820,824 (Joseph et al.); U.S. Pat. No. 6,971,590 (Blette et al.); U.S. Pat. No. 7,032,839 (Blette et al.); U.S. Pat. No. 7,201,336 (Blette et al.); U.S. Pat. No. 7,484,676 (Blette et al.), and in U.S. Patent Application Publication Nos. 2004/0140373 (Joseph et al.); 2006/0065761 (Joseph et al.) and 2006/0102550 (Joseph et al.), etc.

(75) The complete disclosure of the patents, patent documents, and publications cited herein are incorporated by reference in their entirety (to the extent that those teachings do not conflict with the explicit descriptions found herein) as if each were individually incorporated.

(76) Illustrative embodiments of liquid spray guns, liquid spray gun platforms, and liquid spray head assemblies and methods of using them are discussed and reference has been made to possible variations. These and other variations, combinations, and modifications will be apparent to those skilled in the art without departing from the scope of the invention, and it should be understood that this invention is not limited to the illustrative embodiments set forth herein. Rather, the invention is limited only by the claims provided below, and equivalents thereof.