Patent Publication Number: US-11027295-B2

Title: Spray applicator

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention generally relates to spraying apparatus and to nozzles. More specifically, the invention relates to discharging of fluent materials from two or more sources. In another aspect, the invention relates to fluid spraying and diffusing. More specifically, the invention relates to combining separately supplied fluids at or beyond an outlet, where fluid streams have an angular junction. 
     Description of Related Art 
     Current spray technologies require a user to leave the target surface to shut down the materials flow after each swath of spray. Similarly, starting or restarting a spray is done off-target in order to establish satisfactory spray characteristics before moving on-target. These practices waste approximately 30% of the materials. Thus, a 30% waste factor is an accepted fault of current spray technologies. 
     One reason why standard spray technologies have such a high waste factor is the use choked flow fluid dynamics to produce the spray with a convergent-divergent nozzle. A convergent-divergent nozzle employs a mixing chamber, where air and materials meet, behind the nozzle tip. The tip is configured with a smaller orifice hole in the center of the tip, creating a severe restriction. This configuration utilizes the conservation of mass principle to create a spray. Conservation of mass requires fluid velocity to increase as the fluid flows through the significantly smaller cross sectional area of the restriction, powered by compressed air, forcing the materials through the small hole in the tip to create a spray. Starting or stopping the spray process is characterized by errors in the spray pattern, largely due to the time factor necessary to build or dissipate pressure behind the very small, convergent-divergent orifice of the nozzle. 
     Modern spray fluids such as certain vinyl compounds can be heavy, thixotropic compounds. Thixotropy is a time-dependent shear thinning property. Certain gels or fluids that are thick or viscous under static conditions will flow, becoming thin and less viscous, over time when shaken, agitated, or otherwise stressed, thus displaying time dependent viscosity. Thixotropic compounds then take a fixed time to return to a more viscous state. These high viscosity, non-Newtonian vinyl compounds will usually create errors with sprayers employing convergent-divergent nozzle technology. 
     The spray properties of thixotropic compounds and non-Newtonian compounds such as certain vinyl compounds are significantly different from Newtonian compounds. With conventional spray technology, switching from spraying a Newtonian compound to a non-Newtonian compound can require the user to change the spray nozzle or even the entire sprayer and air compressor. 
     Although many applications of spray technology related to the construction industry, spray technology also can relate to fuels and delivery of fuels. It would be desirable to have a spray applicator that is able to spray fuels such as diesel fuel for use in machinery and vehicles. 
     It would be desirable to have a spray applicator that is able to spray both thixotropic compounds or liquids as well as Newtonian compounds, without requiring significant change in settings or applicable equipment. 
     It would also be desirable to have a spray applicator that is able to start or stop the spray process without producing errors, or by reducing or minimizing production of errors, in the spray pattern. 
     To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the method and apparatus of this invention may comprise the following. 
     BRIEF SUMMARY OF THE INVENTION 
     Against the described background, it is therefore a general object of the invention to provide a spray apparatus in which the user is substantially freed from the normal requirement to shut off a materials stream when not engaged in spraying. The user receives the benefit of freeing his hands to handle other issues, which is very important in many applications. 
     Another object is to eliminate the commonly accepted waste factor in spray applications. This spray applicator benefits the user by lessening or substantially eliminating the need to monitor materials flow. The user is able to work without being required to shut off the flow of spray materials when finished spraying. This sprayer operates well without requiring that the user leave the target after each swath. Likewise, the spray applicator can start the spray while aimed on-target. This sprayer stays on-target and sprays error free. The typical 30% waste factor is eliminated. 
     A related object is to provide constant backpressure in a spray apparatus, where a material pumping or supply system overcomes the backpressure during usage to supply material to be sprayed. However, when the material pumping or supply system is paused, the backpressure terminates further feed of the material to be sprayed with no errors or at least with very few errors. The spray nozzle also is cleared so that it can again process material to be sprayed when the material pump or supply system is again triggered, with very few if any errors. 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention, and together with the description, serve to explain the principles of the invention. In the drawings: 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a side elevational view of the spray applicator, showing the delivery mechanism at the left, the spray nozzle at the right, and a central housing providing a front handle and coordinating the positions of the delivery mechanism and the spray nozzle. 
         FIG. 2  is a side schematic view of a modified delivery mechanism employing electric drive to uniformly advance a pushrod. 
         FIG. 3  is a side view of a material supply cartridge loaded in a delivery mechanism similar to a caulking gun, with a broken away surface showing a ratchet mechanism operating a toothed pushrod with advancement pawl operated by a trigger of the delivery mechanism. 
         FIG. 4  is a side view in vertical cross section of a pushrod and pushing piston carrying a relief head such as a cutter head or heater head, located in the delivery mechanism of  FIG. 3 , and also showing a coordinated cartridge piston in a material supply cartridge, configured to deliver contents of the material supply cartridge without being damaged by the relief head. 
         FIG. 5  is an isometric view taken from right side and front position, showing details of the cartridge push plate and of a blow-out relief feature of the cartridge push plate. 
         FIG. 6  is an isometric view taken from right side and front of the pad that will be placed on the face of the cartridge push plate of  FIG. 5 . 
         FIG. 7  is a side view in partial vertical cross section of a spray nozzle assembly. 
         FIG. 8  is a front view of a spanner wrench adapted for turning the nozzle tip. 
         FIG. 9  is a view similar to  FIG. 7 , showing a material supply cartridge in partial cross section as engaged with the spray nozzle of  FIG. 7 . 
         FIG. 10  is an enlarged detail view of the output nozzle assembly of  FIGS. 7 and 9 , showing airflow supplying constant backpressure and clearing the nozzle during nonuse. 
         FIG. 11  is an isometric view taken from upper rear position, showing details of the nozzle. 
         FIG. 12  is a schematic side view of the nozzle emitting a clean spray pattern with will defined edges, and also showing typical waste located outside the edges of the clean spray pattern, the latter being an example of waste produced by prior spray equipment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention is a spray applicator assembly  10  that receives and discharges typically fluent materials from at least two sources. One fluent material is a propellant, often a propellant gas such as air, and for convenience of reference, the gaseous material may be referred to herein as being air, but without limiting the choice of gas to air. The second fluent material, which typically is a liquid-based applied or distributable product, is chosen from a wide variety of candidates. It may be liquid, it may be viscous, and may or may not contain solid particles. By way of example and not limitation, the candidates include caulk-like materials, paint, drywall topping compounds, adhesives, or any of a variety of other materials that are applied by spraying during the construction process, but not limited to these examples. This second material will be broadly referred to as a distributable product. To distinguish the typically liquid-based second fluent material from the gaseous first material, the first material will be referred to as propellant, gas, or air, and second material often will be referred to as the distributable product, although other terminology may be applied where a more specific product is to be referenced. One of the advantages achieved by spray applicator  10  is that it can apply a wide variety of distributable products without requiring a fresh calibration for each. The spray applicator  10  is capable of successfully applying a wide variety of coatings with gas pressure adjusted by a simple proportioning valve. 
     As shown in  FIG. 1 , the spray applicator assembly  10  is air-assisted by a supply of propellant gas from a source such as a schematically shown compressor  11  feeding propellant gas through air supply line  12  that is configured for connection to the compressor  11  or another source of pressurized propellant gas. A quick connect tube end  14  allows ready connection to or disconnection from a source of pressurized gas. The second, fluent material to be applied is provided in a materials container  15  formed of a cylindrical cartridge body  16  containing the second, fluent material between an internal push plate  18 ,  FIGS. 4 and 5 , inside the rear of cartridge body  16 , and a protruding spout  20 ,  FIGS. 1, 3, and 9 , at the front end of the cartridge body  16 . 
     The general configuration of disclosed container  15  is similar to various commercial cartridges containing caulk or other materials that might not be suitable or desirable to be sprayed in an applicator  10 . Containers  15  that are suitable for use with applicator  10  will be referred to as compatible, while any other containers will be referred to as incompatible. It would be desirable to automatically identify which containers are compatible with applicator  10  and which are incompatible. A convenient distinction can be achieved by uniquely configuring the push plate  18  of a compatible container  15 . In turn, the applicator  10  can detect the different push plate of an incompatible container and act in a rejection mode to relieve pressure or harmlessly eject the contents of a detected, incompatible container. 
     The spray applicator assembly  10  has two handles for support during operation. A rear handle  22  is a combination handle that also is a portion of a delivery mechanism or materials pump  24 . As best shown in  FIG. 3 , the rear handle  22  is a portion of a delivery mechanism  24  similar in structure and operation to the handle of a caulking gun. A trigger  28  operates an advancement mechanism to advance a pushrod  30 . For positive operation, the pushrod may be configured with ratchet teeth  32 , and the trigger operates a pawl  34  that engages the teeth  32  and advances the pushrod by trigger movement. A cradle  36  receives the cartridge body  16  and supports it in aligned position for the pushrod  30  to enter the rear of the cartridge body and to advance the push plate  18  therein under pressure from the pushrod. A front end wall  38  of the cradle  36  limits the forward movement of cartridge  16  so that forward movement of the pushrod will first bottom the cartridge against end wall  38  and thereafter will squeeze and eject the contents of the cartridge body through spout  20 . 
     The spray applicator assembly  10  has a forward handle  40 ,  FIG. 1 , that is joined to or is a portion of a central housing  42 . The central housing  42  receives the forward end of the delivery mechanism  24  and supports the delivery mechanism in a desired alignment, described below. The central housing  42  is configured with suitable access openings  46  to allow insertion and removal of materials cartridges  15  with respect to cradle  36 . The central housing also receives and carries an output nozzle assembly  48  that includes an associated air or other gas reservoir  50 . The central housing  42  establishes a spacing and alignment between the carried materials cartridge  15 , the air reservoir  50 , and nozzle assembly  48  as suggested in  FIG. 9 , where the spout  20  is shown to be aligned for axial, centerline reception into or through the air reservoir  50  of nozzle assembly  48 . Thus, the forward handle  40  and central housing  42  serves as a uniting element between the materials supply and the output elements of the spray applicator assembly  10 . 
     The central housing  42  also establishes a spacing and alignment between the delivery mechanism and the output nozzle assembly, such that when a cartridge  15  is bottomed against front end wall  38 , the spout  20  is suitably advanced for sealed engagement with the output nozzle assembly, as described below. 
     In addition, the forward handle  40  may assist in carrying the air supply line  12 . An air line carrier bracket  52  may interconnect forward handle  40  to air supply line  12 . Otherwise, the air supply line  12  is connected to air reservoir  50 . With two connections between the air supply line  12  and the spray applicator assembly  10 , the air supply line is stable even when the user freely moves the spray applicator assembly  10 . 
     With reference to  FIGS. 7 and 9 , the air reservoir  50  conveniently may be formed with a forward-end lid  54  that attaches to the body of the air reservoir  50  as a cap, attached by threads  56 . The lid also defines a central, forwardly extending threaded column  58  that receives the nozzle assembly  48  on threads  62 . The threaded column extends axially into nozzle assembly  48  and defines a plurality, such as four, of equally spaced, axial air passages  64  that communicate from inside air reservoir  50  into a chamber  66  located between the threaded column  58  and the nozzle assembly  48 . 
     The nozzle assembly  48  is able to spray distributable products of widely varying viscosity, with little or no readjustment needed when changing from one sprayed material to another. This advantage follows from several factors. One factor is that the preferred nozzle assembly  48  has an open barrel bore  68  rather than a convergent-divergent type of nozzle as is common to many prior spray devices. Thus, the barrel bore may be considered to be substantially uniform. A second and related factor is that due to the use of the open barrel bore  68 , the preferred nozzle assembly  48  does not require a conventional mixing chamber located behind a nozzle tip with a smaller orifice in the tip to mix the distributable products with air. Thus, according to preferred operation, the nozzle assembly  48  does not force the distributable products out such a smaller orifice with high pressure air to produce a spray. A third factor is that the preferred nozzle assembly is designed to spray the distributable product with significantly less restriction than conventionally used at a nozzle outlet. 
     The output nozzle assembly  48  defines a nozzle bore  68  that is substantially free of restrictions. Bore  68  has an open barrel design with a large through-bore rather than a small orifice design as commonly found in spray guns in the prior art. To produce a spray, first and second fluent materials flow through the open barrel bore  68  without being forced through a tiny, restrictive outlet orifice. 
     The spray applicator  10  receives pressurized air from a source  11  through line  12  and then sequentially through main air valve  70  and into the air reservoir  50 . The supply of air in reservoir  50  can be at a suitable operating pressure, such as 80 to 100 psi. Relatively to some known spray equipment, this pressure might be considered to be low or moderate. This air is converted into a high velocity stream by travel through relatively narrow passages  64 . As a non-limiting example, the reservoir  50  might be cylindrical with two inch diameter and three inch height. The narrow passages  64  might have 3/32 inch diameter, which demonstrates by comparison that the passages are narrower than the reservoir by more than an order of magnitude, which can be expected to result in gas flow through the passages  64  being at a high velocity. The gas flow through passages  64  might continue through passages  72  in a high velocity air stream, leading into a multi-inlet blast chamber within the barrel bore  68  of the nozzle tip that breaks up the distributable product into a spray. Then, the distributable product is pushed out the tip of bore  68  with no restrictions in the end of the tip. As an example, the multi-inlet blast chamber may be fed air from the four inlet passages  64  in lid  54 , where air velocity increases. The distributable product is forced out the tip  68  by the four high velocity air streams generated in the nozzle assembly  48 . Four evenly distributed passages  72  are located forward of reservoir  50  and receive pressurized air from passages  64  in the reservoir lid, producing further high velocity air streams. The four passages  72  are centrally angled to receive some of the output of passages  64  and to direct it through ports  76  into the open barrel contour of the nozzle bore  68  to break up the distributable products into droplets. The function of the angled shafts inside the tip can be different with regard to weather the tip has second materials in it or not. The distributable product is fed into the barrel  68  of the nozzle tip  78  by the axial material transfer tube  74 . As a result, the droplets of distributable product become a uniform high velocity spray that leaves the output nozzle  48  without errors, even while spraying heavy thixotropic compounds. 
     Thixotropy is a time-dependent shear thinning property. Certain gels or fluids that are thick or viscous under static conditions will flow by becoming thin and less viscous over time when shaken, agitated, or otherwise stressed, in what is termed time dependent viscosity. They then take a fixed time to return to a more viscous state. These heavy viscosity, non-Newtonian vinyl compounds, will usually create errors in the spray for sprayers operating with convergent-divergent prior art nozzle technology. 
     The spray output nozzle  48  requires a connected materials cartridge  15  to complete the nozzle assembly  48  by the insertion of a tapered hard plastic spout  20  of the materials cartridge. The inserted spout  20  establishes a temporary water tight seal that seals with the air system in the nozzle and facilitates the feed of distributable product to the output nozzle  48  from the cartridge  16 . 
     The spray applicator  10  is useful wherever a sprayer is needed, especially where the user benefits from not having to monitor the materials flow and be required to shut off the materials flow when finished spraying. The physical requirement of a user having to shut off a materials stream and the benefit of freeing the user&#39;s hands for other issues is very important in many applications. Additionally, current spray technologies require a user to redirect the spray off the target surface before shutting down materials flow after each swath of spray. This practice wastes approximately 30% of the materials. In contrast, spray applicator  10  is capable of terminating spray at the end of a swath, without errors. Consequently, spray applicator  10  need not leave the target after each swath; nor does spray applicator  10  need to start the spray off-target for each new swath. Spray applicator  10  can stay on-target and spray error free. The former waste factor of 30% is vastly improved upon. 
     The forward flow of distributable products often is pressurized by a hand pump or an electric pump. The forward pressure can be regarded as a known quantity because the sufficiency of hand operation or electric pump operation is well established. The nozzle assembly  48  automatically shuts off the forward flow of the distributable products to the nozzle barrel  68  when the pumped forward movement of the distributable products is stopped or paused. This ability results in a shutoff from spraying that is error free. When the flow of distributable products resumes, such as when the user again pumps the materials pump  24 , the nozzle  68  automatically resumes the same spray without error. This performance ability is best understood by reference to  FIG. 10 . A supply of distributable product  80  is pumped forward from the materials cartridge into the material transfer tube  74  under an established forward pressure. At the same time, pressurized airflow from reservoir  50  advances through air passages  64 , with this portion of airflow represented by arrows  82 . Both the advancing distributable product  80  and the pressurized airflow  82  reach primary air chamber  66 . Depending upon dynamic factors, airflow  82  can advance through angled air passages  72  and outlet ports  76  in the nozzle bore, and/or airflow  82  can advance centrally in chamber  66  toward the advancing stream of distributable product  80 . 
     Where the pump  24  is pushing the distributable product  80 , the distributable product  80  will advance through chamber  66  and into nozzle bore  68 . In this situation, the airflow  82  will not prevent the distributable products from traversing chamber  66 . Rather, substantially the entire airflow  82  will advance into the forward passages  72 , where the airflow is indicated by airflow arrows  83 . The four jets  83  transmit a high speed air stream generated by the four high speed air inlets  64  in the primary air chamber  66 . Under certain operational conditions, the air stream  83  may be a supersonic sound wave stream. The wave stream is transmitted into the distributable products received in bore  68  as the distributable products pass ports  76  in the barrel. The pre-spray material flow has secondary contact with the high speed, possibly supersonic air stream when it passes the four ports  76  in the barrel. The spray is now set at correct speed and density and leaves the barrel at a high speed that in hypothetical example may be approximately 790 feet per second. This hypothetical speed is below supersonic but fast enough to stay stable in air. The converging outputs from ports  76  will operate as further described, below, to spray the distributable product  80  from the nozzle. 
     When the pump  24  is not actively pushing the distributable product  80 , the airflow  82  will be partially directed centrally in chamber  66 . A portion of airflow  82 , represented by subsequent airflow arrows  84 , will cut off the supply of distributable product  80  roughly at air chamber  66 . This subsequent airflow  84 , in conjunction with airflow from passages  72 , cleans the nozzle bore  68  of distributable product  80  sufficiently to significantly reduce or eliminate errors in the spray. When pumping of distributable product  80  resumes, the nozzle starts cleanly. 
     Typically, air enters the reservoir  50  at approximately 80 to 100 lbs from a compressor via air tube  12 . This is relatively low pressure and, thus, the spray applicator  10  can use inexpensive compressors. In addition, spray applicator  10  is able to spray many viscosities from the same nozzle assembly  48 , error free. In prior practice, it is often necessary to use high end air compressors with high pressure air supplies to be able to spray high viscosity materials. The spray applicator  10  doesn&#39;t require a user to switch out the nozzle or the compressor to be able to spray paint and then spray a high viscosity material. The same nozzle and compressor can spray both compounds, error free. This advantage doesn&#39;t exist in prior art spray technology. 
     The spray applicator assembly  10  has a main air flow valve  70  that regulates the air flow to the assembly  10 . As an example, valve  70  may have a simple rotatable passage design. After incoming air passes through the main air valve  70 , it enters the main air reservoir  50  where the air is stored in high volume, being replenished continually by the air from a pressure source such as an air tank or air compressor feeding through air line  12 . A suitable pressure source may be any sort of determined or undetermined means or device that provides air at adequate pressure and volume. For convenience of description, the pressure source may be referred to as a compressor, but without limitation to that particular type of pressure source. The air line  12 , itself, may be regarded as being the pressure source. This volume of air in reservoir  50  acts as a buffer, a compensator, and a shock absorber that stops backpressure surges. Reservoir  50  functions as an air storage chamber. The air initially enters this chamber from the compressor or other source and is critical to establishing an even feed of the air into the four shafts  64 . The nozzle  78  shifts from performing a material spray function to performing as an automatic materials flow control device. The nozzle assembly  48  relies on the air storage chamber  50  to absorb the changes in air flow demands, which are different in each mode. Reservoir  50  acts as a shock absorber for the air flow demands of each type of distributable products or no materials in the nozzle. Reservoir  50  allows the nozzle assembly  48  to draw air in case of momentary shortage and to store air in case of momentary excess. The reservoir buffers the air flow so that the nozzle assembly  48  will expel unused air from tip  68 . The air reservoir  50  keeps the nozzle operating smoothly and error free. 
     When the nozzle assembly  48  is not processing distributable products in the barrel  68  of the tip, automatically the air reroutes and causes a backpressure surge. The air reservoir  50  effectively absorbs the backpressure serge to stop siphoning of the distributable products during a reset of materials pump  24 . The air of the backpressure surge holds back the flow of distributable products, automatically. For example, as soon as the user stops pumping the distributable products into the nozzle, the air re-routes within the nozzle and controls the flow of distributable product to stop it from entering the nozzle bore  68 . This instantaneous and automatic stoppage of distributable products flow distinguishes the spray applicator  10  from other known spray nozzle technologies. The use of an air reservoir  50  within the nozzle assembly  48  to start and stop the spray function without error is unique. 
     Switching from spraying a Newtonian compound to spraying a high viscosity non-Newtonian compound such as a vinyl compound or drywall texture compounds can present significant problems with currently conventional spray technology. With some current spray technologies, this sort of change may require the user to change the nozzle or even the entire sprayer and possibly change the air compressor, as well. By comparison, the applicator assembly  10  is capable of switching from a high viscosity, non-Newtonian compound to a thixotropic compound or to a liquid compound such as a paint or adhesive compound. The nozzle assembly  48  of the spray applicator assembly  10  may require the user to reset the main air valve  70  on the tool according to the type of materials to be sprayed, but with no change of compressor or no change to another variation of the spray applicator assembly  10 . The spray applicator assembly  10  is capable of spraying many viscosities of distributable products while using a single spray applicator assembly. In addition, the spray applicator assembly  10  requires only low volume air compressors, which are not expensive to buy. 
     Many currently supplied sprayers use choked flow fluid dynamics to produce supersonic velocities for creating a spray. In such conventional sprayers, the sprayed materials are shot from an orifice of the tip at supersonic speeds by the force of high powered air streams. The size of the nozzle orifice relates to the speed of the air, the materials mixture, and the spray size. These conventional spray systems need high powered air compressors to be able to spray heavy materials. This is an expensive endeavor. Both the high powered compressors and the material pumps are expensive. In addition to the expense, such known systems can encounter difficulty when the sprayer has to share the compressor with the materials pump. The problem is exacerbated if the pump also is trying to pump a heavy compound, because the pump can rob the air power from the spray nozzle. For example, it is well known that nozzles have extreme problems being able to spray heavy vinyl compounds. 
     Thixotropic compounds typically are resistant to flow through a hose. Standard spray methods often cannot spray them, because most sprayers require the distributable products to be delivered by a hose to the spray system. In contrast, the spray applicator assembly  10  utilizes a cartridge system for delivering distributable products, resulting in very short material transfer distances from the cartridge  15  to the nozzle assembly  48 . The cartridge system is closely similar to achieving materials delivery of thixotropic material compounds to the nozzle without a hose. Thixotropic materials are resistant to flow and sag, and thus they are very hard to spray. There are no typical, lengthy delivery hoses in the spray applicator assembly  10 . As contrasted to standard spray technology, in the spray applicator assembly  10  thixotropic materials are not forced into a pump attached to a lengthy hose and then attached to a spray gun. Thixotropic materials in the spray applicator assembly  10  do not clog hoses and are not compressed into a hose. Compression is known to damage some compounds and tends to damage the integrity of the compound before it is sprayed. Nozzle assembly  48  does not damage the integrity of such materials. 
     The spray applicator assembly  10  combines the function of a materials pump with a nozzle assembly. This combination has the advantage of eliminating the need to maintain long hoses and fittings. Commonly in prior art, feed lines for distributable product requires high maintenance, such as cleaning a fifty foot hose and disassembling several valves. This high degree of maintenance can easily result in the need to replace hoses and valves on a frequent basis, such as every month. An air feed system on a spray system using a conventional mixing chamber can require similar high maintenance and frequent replacement. 
     In the spray applicator assembly  10 , the output nozzle assembly  48  handles thixotropic materials in a new way. These materials are prepared for spraying in the open barrel nozzle  68 . Air from reservoir  50 , typically at source or compressor pressure of 80 to 100 psi, is routed into four evenly spaced air passages  64 , which in accordance with  FIGS. 6-8  are axially directed and formed in a forward lid  54  of the air reservoir  50 . Each of the passages  64  is about 3/32 inch diameter and about an inch in length. These passages function as Venturi tubes that increase the velocity of the transmitted air according to the Bernoulli principle. The air streams from passages  64  then enter the converging passages  72  and enter the nozzle bore  68  at high speed, at locations about ⅔ of the distance behind the outlet tip. Four jets of air from angled passages  72  advance through four large oval shaped ports  76  that are located in the barrel of the nozzle bore. The nozzle bore functions as a blasting chamber within the tip. Notably, functioning as a blasting chamber differs from functioning as a mixing chamber. The operation of a blasting chamber doesn&#39;t mix the distributable products with the compressed air, as occurs when typical nozzles force the mixture out of a mixing chamber and through a tiny orifice. 
     The four high velocity air jets coming from the tubes  64  in the threaded column  58  enter the nozzle assembly evenly and in an equally spaced pattern in the circumference of the threaded column  58 . The primary air chamber  66  is defined between threaded column  58  and the nozzle assembly  48  and, as a hypothetical and non-limiting example, may be about 3/32nds inch deep. This space is a secondary air reservoir. The air from passages  64  enters the primary air chamber  66  and from there enters the four secondary, angled tubes or Venturi passages  72 . As a further hypothetical and non-limiting example, the angled Venturi passages  72  are arranged at an angle of 26 to 28 degrees relative to the longitudinal axis or centerline of the nozzle bore  68 . The four secondary Venturi passages create high pressure jets in the nozzle tip. The secondary Venturi jets also channel the high velocity air flow at an angle in the nozzle bore  68 . Each of the four elongated, oval ports  76  enters the barrel in a position approximately opposite to another of the ports. The four elongated air ports take up approximately 75% of the barrel circumference. This creates a blasting chamber driven by high velocity air streams from these ports  76  and on the radii of the barrel bore. 
     The accelerated air streams entering bore  68  hit the distributable products passing through the turbulence of these air streams. The distributable products are broken down into droplets. Then the high volume, high velocity air stream escapes from the barrel bore and forces the droplets of distributable products out of the barrel bore  68  at speeds that achieve a spray. The droplets of distributable products are blown out of the barrel bore  68  by air at a high velocity, created by the nozzle assembly. Unlike typical spray operations, the droplets are not forced through a restricted tip orifice from a mixing chamber located behind the restricted tip orifice to achieve a spray. 
     Standard spray technology often places a mixing chamber in-line with a spray orifice and directly behind the spray orifice. In nozzle  78 , a limited mixing takes place when air from passages  64  and  72  meets distributable products in open bore  68 . However, the method practiced in nozzle  78  differs from other techniques because the air stream does not force the distributable products through an orifice in the nozzle. Where the term “nozzle” has been used in certain examples from the prior art, the presence of a taper or constriction optionally might be implied. Such implication is not applicable to the present nozzle  78 . This difference is evident from analysis of the sprayed material after it hits the sprayed surface, where it is evident that the sprayed materials are not loaded with tiny bubbles, as often seen in typical spray applications. 
     A further distinction from standard spray technology is that spray apparatus  10  produces a flat, even spray pattern, where standard sprays create a center loaded pattern. Typically in prior art, when a spray system forces the material to be applied to thoroughly mix with the air, the air pushes the materials out a tiny orifice to establish a spray. The consequence is a center-loaded effect called a “bull&#39;s eye.” The user typically tries to hide the bull&#39;s eye effect by indiscriminately moving or waving the sprayer to hide this effect. In contrast, the spray apparatus  10  produces a far flatter spray, allowing a user to spray each single swath with a substantially even coat. 
     Attempts to spray thixotropic material using a conventional mixing chamber and with conventional spray equipment are subject to special limitations. Two prerequisites are needed to achieve successful spray. The first prerequisite is that the thixotropic material must enter the standard mixing chamber. Typically the first prerequisite is met by pumping the thixotropic material into the mixing chamber. The second prerequisite is that the material to be applied that reaches the standard mixing chamber must flow into the path of the air stream. With thixotropic material, the second prerequisite is the problem. The air stream in a conventional mixing chamber can blow a hole through the thixotropic material, but under these conditions such materials lack flow and will not flow into the path of the air stream. A standard mixing chamber and a tip assembly will not reliably spray thixotropic or thick flow resistant materials very well, without errors. 
     With spray applicator  10 , thixotropic materials are transferred a very short distance, such as only two inches of inline movement without restricting the thixotropic material. Movement over this minimal travel distance conquers the fact that thixotropic materials are resistant to being pumped long distances to a nozzle and thus cannot be sprayed very easily with conventional equipment. In spray applicator  10 , the nozzle bore  68  does not store materials to be sprayed. Thixotropic materials enter an unobstructed barrel  68 , which is open to the degree that it has no restrictive tip connected to the barrel. Thus, barrel  68  my resemble a conventional mixing chamber because spray materials meet the air in the barrel, although conventional mixing of air with spray materials is absent. 
     From nozzle bore  68 , spray droplets are forced out the front-end of the nozzle bore  68  primary by high velocity air flow that is present in the primary air chamber  66 . The air mass builds in the primary air chamber  66  accordingly, with respect to the usage factor of the tip, such as by whether the tip is processing distributable product or is at rest with no distributable products being processed in the tip bore. This unique function is enabled by the airflow from the main air storage chamber in reservoir  50 . The reservoir  50  increases its air and regulates the air flow within the nozzle to allow the proper airflow for each function the nozzle requires, automatically. Without this reservoir  50 , the nozzle assembly will be starved of air when spraying and have spurts of air from when the nozzle is at rest with no distributable products in the nozzle. The reservoir chamber acts as a compensator with regard to airflow control in the nozzle. This is a reason why the air reservoir  50  is attached to the nozzle assembly as a part of the nozzle. 
     The nozzle assembly  48  uses the Laval theory of choked flow with respect to airflow only. The distributable products and air are not mixed, in contrast to the common practice when a convergent-divergent restriction with small orifice is present. The latter reflects the conventional occurrence when air forces a mixture of a distributable products and air through a small orifice to produce spray. The Venturi effect is only applicable in the nozzle assembly  48  of the spray applicator assembly  10  in the air system and not with respect to the creation of the spray. 
     The air system of the spray applicator assembly  10  creates the basis to apply the Bernoulli principle to describe the performance of the nozzle  68 . The conservation of mass principle requires the air velocity to increase as the air flows through the smaller pipes  64  into the primary air chamber  66  from the air reservoir  50 . At the same time, the Venturi effect causes the static pressure, and the density of the air stream, to decrease downstream, beyond the restriction. However, the velocity of the air stream is substantially increased before it enters the nozzle bore  68 . Thus the higher velocity air is injected into the nozzle tip by the four Venturi tubes  72 , which enables the nozzle to blast the higher viscosity materials into droplets without needing to employ an expensive compressor to provide air with very high cfm and psi characteristics. 
     Spray applicator assembly  10  employs a drive system in the materials pump  24  that is similar to a modern caulking drive system. This drive system requires that the pushrod  30  not relieve itself in forward movement as takes place with modern anti-drip caulking gun drives. The drive system of materials pump  24  stays stationary in forward movement between pump strokes. Modern caulking guns are dripless and relieve the forward pressure that the pushrod and piston exert on the push plate in the caulking tube. The materials pump  24  is a stationary hold type mechanism and does not relieve the pressure developed from prior pumping of distributable products. At the end of a pumping session, materials pump  24  holds the pushrod and piston in the same position as when pumping session ended. The pushrod is not able to reverse itself and relieve pressure after each stroke. 
     The pushrod in the sprayer also is not allowed to be forced backward when the operator is adjusting the air. The sprayer is equipped with a lock-drive ratchet system that has a much tighter grip on the pushrod so as not to allow the pushrod to be forced back from the air pressure in the tool. 
     To load a new materials cartridge into the spray assembly  10 , the user pulls back the pushrod  30  by releasing a latch lock  86  on the rear of the pushrod. The release mechanism of the latch lock  86  disengages the ratchet teeth and allows the user to pull back the pushrod  30 , together with the piston  88  on the front of the pushrod. When the pushrod is sufficiently out of the old cartridge body  16 , the user removes the old materials cartridge  15  from the cradle  36 . Then the user trims the forward end of the new, sealed, tapered plastic spout  20  with a cutting knife, removing about ½ inch to expose the distributable products in the spout. The user places the new materials cartridge  15  in the cradle  36  of the spray tool  10  and pumps once on the pump trigger  28 , pushing the new cartridge forward until restrained by the front end wall  38  of the cradle. End wall  38  establishes the maximum forward position of the cartridge, where the tip of the new plastic spout is adequately pushed into the back end of the plastic materials transfer tube  74  in the body of the spray applicator  10 . The forward motion of the new cartridge establishes a temporary, water tight connection between the new spout  20  and the rear end of the material transfer tube  74 . A elastic ring such as a rubber grommet  90  seals the material transfer tube to the tube port in the back wall of the air reservoir  50  and aids in forming the seal between the material transfer tube  74  and the spout  20 . When spout  20  enters the rear end of the materials transfer tube  74 , the grommet  90  comprises a compression ring around the end of the tube  74 . The spray applicator  10  maintains the forward motion and the temporary water tight connection, completing an air lock so that the spray applicator assembly has sources of both air and distributable product. The user then adjusts airflow at valve  70  to a point where he feels the pushrod shift its load due to backpressure, which indicates a correct setting for proper airflow. The user then is ready to spray the new cartridge of distributable product. 
     As best seen in  FIG. 9 , the preferred contour of the spout  20  is to have a nose  117 , where the nose  117  has a convenient original length such as 1.5 inches. To open the cartridge for use, the user can trim off a portion of the nose, such as approximately one-half inch from the new cartridge nose  20 , leaving a sufficient residual nose length to engage in the tube  74  of the nozzle. Nose  117  has a forward taper with a diameter that is smaller than the entrance into the material transfer tube  74  of the nozzle assembly  48 . Behind nose  117 , the spout forms a backward flare  118  at an angle of approximately 47 degrees to center line of spout  20 , which is a suitable angle to engage in tube  74  and spread the receiving end of tube  74  to create a temporary water tight seal with tube  74 . Nose  117  and flare  118  also create a seal with o-ring or grommet  90 , which is positioned between the tube  74  and the edge of the tube port in the back wall of the air reservoir  50 . The proper relative positioning and sealing between cartridge  15  in cradle  36  and nozzle  48  is ensured by central housing  42 , which receives the cradle and nozzle in predetermined relative positions that establish the desired seal. 
     Behind flare  118 , the spout  20  forms a tube-connecting portion  119  that communicates with the interior of cartridge body  16  to deliver carried material to the forward portions of the spout. A suitable diameter for connecting portion  119  is ⅝ inch. The tube spout  20  is made of hard plastic material so as not to be crushed while establishing the connection with the materials transfer tube  74  and grommet  90 . Thus, spout  20  must be hard and strong enough that it can be pushed forward into place and pumped. The spout must expand the plastic material transfer tube and expand the rubber o-ring or grommet  90  in the back of the air chamber. The junction between the cradle  36  and the nozzle assembly  48  is coordinated with the size and proportions of the materials cartridge  15 . In greater detail, the position of the front wall  38  of cradle  36  is coordinated with the position of the rear end of tube  74 , so that the cartridge spout will seal with the material transfer tube  74 . Thus, the cartridge  15  is coordinated in size to properly perform in the spray applicator assembly  10 . 
     The main airflow valve  70  of the nozzle assembly  48  is where pressurized air enters the assembly. Valve  70  is sufficient to serve as the only air adjustment in the spray assembly  10 . The air from a compressor enters the spray nozzle assembly  48  at air reservoir  50 , where the air is stored at high volume and is continuously replenished by the air from the compressor. This volume of air in reservoir  50  is both a buffer and a reservoir. This volume of air also is a compensator and shock absorber that allows the nozzle assembly  48  to have adequate air for operations. When air is not being used, the air in reservoir  50  buffers airflow so that the nozzle  48  will expel the unused air out the nozzle tip piece  78 . The shock absorber aspect of the air volume in reservoir  50  is to stop backpressure surges. The operation of the reservoir  50  keeps the nozzle assembly  48  running smoothly and error free when the nozzle is not processing the material to be sprayed in the open barrel tip  68 . The air reroutes automatically and causes backpressure surges, which the air reservoir absorbs very effectively. 
     According to a non-limiting example of the spray applicator  10 , revealing details of preferred dimensions and operating parameters, the nozzle tip  68  receives four high velocity air flows that originate from the air passages  64  and feed into the nozzle assembly  48  at primary air chamber  66 . From the primary air chamber  66 , the pressurized air is routed forward in the nozzle assembly  48  through four secondary Venturi tubes  72  in the nozzle tip  78 . The air is again accelerated in the passages  72 . Then, the air in the tubes  72  exits these tubes and enters the open barrel bore  68  approximately ⅔rds of the distance behind nozzle outlet. Tubes  72  enter the open barrel bore  68  from four elongated oval ports  76  that are spaced evenly in the radii of the barrel and converge toward the same point within the barrel  68 . 
     According to a further aspect of this non-limiting example, the tip piece  78 ,  FIG. 9 , of the nozzle assembly  48  is formed of one piece with about ¾ inch in axial length and ⅝ inch in diameter at the rearward end. A 3/32 inch depression is formed into the rearward end of the tip, forming primary air chamber  66 . A circumferential 1/16 inch lip  92  surrounds the primary air chamber  66  at the outside edge. The open barrel bore  68  of the tip of the bore is about 134 thousandths inch diameter, which makes it just over a ⅛ inch bore. It is drilled along the axial centerline of the tip and extends entirely through the tip. The axially rearward end  94  of the barrel bore  68  has a 3/32 inch bevel, best seen in  FIGS. 10 and 11 . Each of the four angled holes  72  has approximately a 1/16th inch radius and is formed in the forward wall of the primary air chamber  66 . The angled holes  72  are drilled in the tip piece  78  at an approximate angle of 26-28 degrees and extend from the forward wall of the primary air chamber  66  to a point in the open barrel  68 , approximately ⅔rds up the barrel  68 . The barrel bore  68  is approximately ½ inch long and 0.067 inches wide in radius. The bore hole in the nozzle is substantially uniform at least forward from outlet ports  76 . A tapered collet  96  is contoured to fit around the circumference of the tip piece  78  and engages threads  62  to tighten against the tip piece to hold the tip piece  78  in fixed position on the nozzle assembly  48 . When slightly loosened, the collet allows the tip piece  78  to be rotated as may be desired, such as to adjust the alignment of passages  72  with respect to passages  64 , which can alter air flow between passages  64  and  72 . 
     Continuing with the non-limiting example, to aid in rotating the tip piece  78 , the tip piece may be configured to rotate in cooperation with a wrench  120 ,  FIG. 8 . For example, the front surface of the tip piece may be configured with shallow holes  97  positioned to receive mating pins  122  of a spanner wrench  120  to assist in rotating the tip piece  78 . One method of adjusting the rotational position of the tip piece  78  is to loosen the collet  96  so that the tip piece can be rotated. Using a wrench that has a center hole  124  the same size as the barrel outlet, the tip piece  78  can be rotated while the spray applicator  10  is in operation, spraying through the center hole  124  in the wrench. With the spray applicator  10  in dynamic operation, the spray can be evaluated according to varied characteristics of air flow between passages  64  and  72  and empirically adjusted to the user&#39;s preference. The wrench can hold the tip piece in the desired orientation while tightening the collet  96 . The face plate  126  of the wrench is sized to overlap the leading edge of the collet  96  so that the collet cannot be over loosened during the adjustment.  FIGS. 7 and 9  show the collet  96  extending further forward than the nozzle tip  78 . A forward extension of about 1/16 inch when the collet is tight is acceptable. As the collet is loosened on threads  62 , the collet increases its forward extension. A sufficient forward extension of the collet will push the wrench to disengage the pins  122  from the holes  97 . Over loosening the collet might otherwise result in pressure leaks around the tip piece during adjustment, which might result in an inaccurate adjustment. Thus, the length of pins  122 , the depth of holes  97 , and the relative forward extension of the collet with respect to the tip piece at various degrees of tightening are variable factors in determining how loose the collect can be made when adjusting the rotational position of the tip piece  78 . 
     This method of setting the tip piece  78  is especially useful when using the same nozzle, first, to spray a low viscosity liquid and, second, to spray a high viscosity material. For the former, a heavier backpressure in the tip is useful to control liquids from moving into the nozzle during reset of the material pump handle  28 . The nozzle should have the sets of ports  72  in the tip piece  78  and ports  64  in the threaded column  58  out of alignment, thereby establishing heavier backpressure in the tip piece  78 . For the latter, when spraying higher viscosity materials, the ports can be set straight across from each other so as to rout more air to the function of processing distributable products and less air to controlling flow. 
     The method of adjusting the nozzle can begin with the tip secured by the collet on the threaded column  58 , with the holes  64  and  72  aligned. Next, the collet is slightly loosened on the threads  62 . The pins  122  of spanner wrench  120  are engaged in holes  97  on the front of the nozzle. Turning the wrench adjusts the relationship between the holes  64  and  72 . Positioning the holes out of alignment results in higher backpressure within the primary air chamber  66 , which is beneficial for controlling liquids. When the second material is liquid, higher air pressure in the rear of the nozzle is desirable to stop the liquid from escaping past the primary air chamber and causing errors while the user is resting the spray apparatus. Positioning the holes in alignment increases air in the forward part of the tip, which better breaks up thick materials. When the desired adjustment is reached, the user can pause spray apparatus  10 , remove the spanner wrench from the nozzle tip, retighten the collet, and then resume spraying. 
     In the nozzle assembly  48 , air is vectored through the several tubes  72  in a forward converging pattern that meets in the barrel  68 . The forward openings  76  of the converging tubes  72  are located near the rearward end of the open barrel  68 . The angle directs the air streams to meet in the center of the barrel, where the air streams meet near the centerline of the open barrel. The axial material transfer tube  74  receives distributable products from the materials pump  24 . Tube  74  extends from the rear of the nozzle assembly  48  to the primary air chamber  66 , where the distributable product meets the high pressure air from the primary air chamber  66 . The high pressure serves as a backpressure applied to the distributable products immediately before the distributable products enter the open bore  68 . This backpressure is in the tip piece  78  throughout operation of the spray applicator assembly  10 . Thus, the distributable products are forced past the primary air chamber  66  during the pumping of the material delivery pump  24 , which forces the distributable products forward into the open bore nozzle  68 . While the material delivery pump  24  is resetting between successive pumps, the air from the primary air chamber  66  automatically holds the distributable products at check until the user forces the next pump of materials through the tip. 
     Thus the user can stop pumping materials at any moment or at the end of each pump cycle to reset the trigger  28  without the sprayer sucking and siphoning the distributable products through the nozzle, as otherwise tends to be standard technology. This nozzle assembly  48  automatically shuts off all the materials flow when the user is not pumping the materials pump  24 . The nozzle  68  blows clean air with no errors or spitting as happens in a conventional sprayer when materials flow is shut off. Thus, with spray applicator assembly  10 , no errors happen when the user stops and starts the spray while the sprayer is still aimed on the target. Stopping and starting spraying while on-target does not cause errors in the spray. 
     A materials container  15  contains a charge of distributable product in the cartridge body  16 . With reference to  FIGS. 4 and 5 , the advancing piston  88  on the pushrod  30  will advance an internal push plate  18  in the cartridge body  16 . In turn, the push plate  18  ejects the charge of distributable product through the spout  20  as the internal push plate  18  is advanced. As a safety factor, the internal push plate  18  is configured to allow the backwards release of the cartridge contents, to prevent other types of failure or blowout in case overly high air pressure is applied to the spray applicator  10 . For example, overly high pressure otherwise might cause rupture of the cartridge body  16 . As best shown in  FIGS. 5 and 6 , a multi-layer sealing pad  98  is attached, such as by adhesive or heat, to the forward face of the push plate  18 . A suggested structure for pad  98  is a forward layer  128  of water resistant plastic film, a center layer  130  of aluminum foil or plastic film, and a rearward layer  132  of sealable polyfilm. The polyfilm layer  132  of the seal is a plastic material that can be glued to the push plate  18  and is compatible with permanent glues on the seal. The interior layer  130  of the seal composition is metal foil or thin plastic film. The outer layer  128  is another film designed to blow out at a certain air pressure, such as 140 psi, that is well above the suggested operating pressures of 80 to 100 psi. The pad  98  may have a designated central break-away portion  100 . The forward face of the cartridge push plate  18  is configured with a central opening or break-away panel  101  behind the pad portion  100 . If too much backpressure is applied to the contents  80  of the cartridge  15 , for example by over pressure in primary air chamber  66 , breakaway pad portion  100  and breakaway push plate portion  101 , where used, open to provide a relief passage to the rear of the push plate  18 , allowing the contents of the cartridge  15  to drain to the rear in a controlled manner instead of rupturing the cartridge in another way. 
     As a further safety measure, the pushrod  30  is configured to relieve the contents  80  of incompatible containers by an interaction with the push plate  18  of each container loaded into the spray applicator assembly  10 . A preferred structure for a push plate defeating device is shown in  FIG. 4 , where the pushrod carries a piston  88  that houses a push plate defeating device or relief mechanism  102  in its forward end. For general convenience and safety, the piston  88  and relief mechanism  102  may be positioned such that the mechanism  102  is protected within the piston before the piston is applied to the push plate inside a cartridge  16 . A spring  103  urges the mechanism  102  to remain in protected position within piston  88 . Advancing the pushrod overcomes the force of spring  103  to advance the mechanism  102  from the front of the piston, toward the push plate, by a limited available distance. 
     The push plate  18  is configured to space the material contacting front wall of the push plate forward from the piston. Where this forward spacing is greater than the limited advancement available to the mechanism  102 , the relief mechanism  102  does not reach the forward wall of the push plate to vent or disable the container  15 , and the container  15  is considered to be compatible with applicator  10 . On the other hand, with a container  15  where the forward wall of the push plate is spaced from the piston by less than the limited advancement available to mechanism  102 , the relief mechanism  102  reaches the forward wall and, in response, vents or disables the container  15 . This latter type of container  15  is considered to be incompatible with applicator  10 . 
     A suitable configuration for a compatible push plate  18  in a compatible container  15  is to have a peripheral wall  19  extended by the necessary distance toward the rear of the cartridge  16 . Other types of spacers or standoffs can be used, as well, to prevent the relief mechanism from defeating the compatible push plate or cartridge. In an example, the mechanism  102  acts on the incompatible, contacted push plate to disable it by forming a hole in the incompatible push plate. An incompatible container is thereby disabled from delivering its material charge  80  to the material transfer tube  74  or nozzle. Instead, the material within the incompatible container vents backwards through the formed hole, which also alerts the operator of the spray apparatus. 
     According to the described scheme, a typical relief device  102  in some way punctures the push plate. One type of puncturing mechanism might be a cutter head that the pushrod can push through the front wall of an incompatible push plate. Another relief device might be a heated head that can melt a hole in an incompatible push plate, using a battery powered hot tip similar to the tip from a cordless soldering iron. Once the internal push plate in an incompatible cartridge is opened by a relief device  102 , the contents  80  of the incompatible cartridge may be pushed rearward due to further advancement of piston  88  and by the backpressure from the nozzle  48  applied to the forward end of the material transfer tube. To help guide the disposal of the vented contents  80 , a hollow pushrod  99  may be used to provide a rearward passage for the contents to follow. Likewise, the puncturing head of relief device  102  may be configured as a ring so that the vented contents of the incompatible cartridge can pass through the puncturing head to reach the hollow pushrod. 
     With reference to  FIG. 2 , a substitute for hand pumping the distributable product  80  may employ an electric materials pump  104 . A rechargeable battery  106  is carried on handle  108  and powers an electric drive motor  110  when trigger  112  is actuated. The drive motor  110  operates drive gear  114 , which operates driven gear  116 . The driven gear  116  engages the teeth of the pushrod  30  to advance the pushrod at a suitable speed. 
     As previously explained, with prior conventional sprayers there is a 30 percent waste factor because the user has to stop spraying and start spraying off-target to get an error free sprayed surface. All current spray systems waste a 30% factor, including also the airless systems. The present spray applicator assembly  10  overcomes these problems by, inter alia, providing full time back pressure that stops the errors as soon as the backpressure is not overcome by active pumping of the distributable products to be applied. 
     Reduction in waste factor is a significant advantage achieved in this spray applicator  10 . High waste factor and other problems are unavoidable according to the technology used in prior art spray systems, which do not increase air flow to similar high velocities. According to a hypothetical, non-limiting example, the four passages  64  of the present spray application each support air speeds of 1095 feet per second or above. Preferred speed is slightly below supersonic air flow to the nozzle. The spray assembly converts 90 psi @ 5.6 cfm to such a substantial air speed and delivers it into the base of the nozzle through the four passages  64 . Then, desirably, the nozzle is configured and operated to convert this high speed air into exit speed of approximately 790 ft. per second, which is subsonic, to prevent wind shear of the spray pattern in the static air between the target and the spray nozzle  78 . This eliminates the waste found with many common prior art sprayers. 
     Making the tip  78  from a metal such as brass, like a musical instrument, appears to be important. Modern brass horns and other brass instruments often are formulated using proprietary brass recipes. Different formulations of brass content apparently achieve different resonance. Likewise, the nozzle tip  78  may resonate according to the formulation of the metal used in construction. This brass nozzle and the brass thread column  58  can add to the easy breakdown of the feed of distributable products, especially thixotropic materials, running through this assembly. 
     The four separate air streams  82  from corresponding four passages  64  are fed into the primary air chamber  66  at the speed achieved in the passages, estimated to be just under mach 1, or 1095 ft. per second with presently used passage and chamber sizing. Of course, the sizes of the various passages and chambers can be changed to establish higher air speeds or lower air speeds. These air streams  82  are equally spaced around the chamber  66 , on equal radii from material transfer tube  74  that feeds the nozzle bore  68 . Within chamber  66 , the combined input of these four jets  64  acts on the material from tube  74  by applying a resonance around the material. When the passages  72  in the nozzle tip are rotated out of alignment with jets  64 , resulting changes in resonance can result, with variable applications to the material from tube  74 . To further enhance the effects of resonance, it may be desirable to form the nozzle assembly from multiple materials. For example, sonic-related parts might be made of brass or another resonate metal, while the rest of the nozzle might be made of a non-resonate material such as plastic. Materials transfer tube  74  beneficially might be made of brass with an expansible plastic end on it for the tube connection. Resonance can be enhanced by use of a brass materials transfer tube rather than a full plastic tube. Presently, it appears that sonic resonance is being transmitted backwards through the materials flow in the materials transfer tube as the materials to be sprayed are being pumped towards the nozzle from the materials transfer tube. 
       FIG. 11  shows the rear face of the nozzle  78 , showing the in-flow end  134  of the angled passages  72 . The angled passages are bordered by the inner beveled surface  94  of bore  68 . At the in-flow end  134 , the passages  72  cut through a portion of the beveled surface  94  to define U-shaped or V-shaped flute cuts  138  that communicate between the beveled surface  94  and the passage side wall  66 . The flute cuts  138  are believed to relate to sonic resonance being involved in the cause of breaking up thixotropic distributable products. The shape of the flute cuts is at an intersection between the beveled inner surface  94  and each of the diagonal cylindrical air paths  72 . It has been postulated that the U-shaped or V-shaped flute cuts perform somewhat like the opening in an organ pipe or like one might carve in the bark of a willow whistle. This U-shaped or V-shaped opening appears in various sound generating instruments and may indicate the generation of supersonic sound waves by high speed air flow from primary chamber  66  into each of the air paths  72 . Supersonic waves might travel from each of the four U-shaped or V-shaped openings to bevel-walled chamber  66 , converging in the nozzle bore  68  where they begin to break distributable product into droplets and propel it forward. The distributable product is further broken up into smaller droplets when it is blasted again by air exiting flow paths  72 . Exiting the four channels  72  will be four jets of air vibrating at the same ultra-sonic frequency, the energy of which further breaks up the distributable product into droplets before exiting the nozzle. In addition to participating in the application of ultra sonic waves, the bevel  94  also helps distributable product to travel from the larger materials feed tube  74  to the smaller barrel  68  of the nozzle tip. 
     Analysis of air flow through the nozzle shows the following: assuming the in-flow channels  64  have inner diameter of 3/16 inch, cross-sectional area is 0.11 sq. inch. Air flow is 0.84 cu. ft. per sec. Air velocity is 1095 ft. per sec. The illustrated design uses air pressure of 90 psi and converts it at passages  64  into four jets of air that are very close to supersonic speed air streams. High speed air at near supersonic speed combines with distributable product-bearing droplets. 
     The barrel  68  is smaller than the outlet port of distributable products feed tube  74 , resulting in use of the angle. Distributable products are compressed in the barrel  68 . In the barrel the four tear drop shaped exit portals  76  take up around ¾ths of the barrel circumference at their entry position inside the barrel  68 . This allows distributable products to be formed by the air stream with a very effective radial contact with the airstream to finalize droplet formation. Sonic resonance levels here are predictable. When these angled tip shafts  72  are rotated out of alignment with the four column air shaft feeds  64  in the primary air chamber, the resonance is increased and back pressure is created, which holds back the distributable products in the nozzle. This aspect is what is used to set the nozzle for spraying a liquid solution like paint. Thus the same nozzle that sprays a texture compound can spray a paint compound with no changes of components in the nozzle assembly. The higher sonic levels assist in breaking up the paint into fine spray. The higher back pressure aids in controlling the forward movement of the liquid. 
     When distributable products pass over the angled cuts in the base of the tip  78  and pass the holes  134  in the barrel, a sonic response is created, similar to what happens in an organ or flute. When distributable products pass the four flute cuts, a further sonic response is created. 
     The nozzle  78  functions differently when it has distributable products within the barrel  68  of the tip versus when it is functioning without distributable products within the barrel  68  of the tip. When only the high speed air stream is in the tip, the nozzle assembly and the tip  78  act as an automatic materials flow valve or control without having an actual flow control valve in the assembly. The tip-nozzle assembly automatically shuts off forward flow when there are no distributable products present inside the nozzle tip  78 . Thus, when there are no distributable products being forced into the tip  78  by the materials pump, air traveling into the tip  78  from the primary air chamber  66  takes the widest and least resistant route to go out the tip. The airstream travels up the barrel  68  of the tip, and a small amount travels up the tip&#39;s angled portal tubes  72 . The heavy airstream traveling out the tip is in the barrel  68  when no distributable products are being pumped into the barrel. This airstream passes the four radially placed opposing portals  76 , which are the tear drop portals in the barrel, about ⅔rds of the distance up the barrel. 
     When the high velocity airstream passes the portals  76 , an evenly formed vacuum pocket is formed below the four opposing teardrop portals  76  in the barrel. This vacuum pocket creates within it an area of back pressure. This backpressure holds distributable products from moving evenly in the materials transfer tube  74 , stops siphoning of the distributable products into the air stream, and assists with other issues that create errors when flow of distributable product is interrupted. Any reason for interruption to an even flow in a standard spray system causes errors in the spray. The present nozzle assembly allows interruption in flow of distributable products and will not create errors when interruptions occur in the flow of distributable products to the tip  78 . The exit spray velocity from the nozzle  78  is approximately 790 ft. per second. This is subsonic spray from the nozzle. This means the spray is produced inside the primary air chamber  66  as the materials pass the space where the four Venturi tubes  64  in the thread column  58  release the high velocity air streams into chamber  66 . The nozzle produces a spray without the use supersonic speed at the nozzle tip  78 , unlike many prior known sprayers. This reduces waste to a very low factor, which results in almost no airborne contaminants bring present in the environment of the sprayer, very low fallout in a room, and minimal masking requirements. 
     The spray is made inside the nozzle assembly. Then the spray is blown out the nozzle at subsonic speeds, which lowers the air velocity of the spray and stops air from shearing the spray cone  140  as it moves to the target. As an example of a clean spray cone achieved with applicator assembly  10 ,  FIG. 12  illustrates a very clean resulting spray cone pattern  140  with sharp edges  142 . A portion of  FIG. 12  also illustrates waste as found in many prior art spray devices, where peripheral droplets  144  are found outside the sharp edges of the clean spray cone  140 . The spray of applicator assembly  10  is thus very stable in flight. The spray pattern edge  142  is substantial in nature and is very resistant to air shear, which otherwise is created by the spray traveling through the stagnate air in between the nozzle of the sprayer and the target. This invention is able to create spray inside the nozzle by employing substantially higher air velocities than found in prior art, whether considering airless or air-assisted technologies where the spray leaves the muzzle of the nozzle at supersonic speeds to achieve a spray. 
     The four airstreams  82  feeding the nozzle move at transonic speeds into the primary air chamber  66 . The spray leaves the nozzle muzzle with this subsonic flow rate. This subsonic muzzle velocity is set at just under supersonic speed. This exit speed is low and thus is a substantially improved exit velocity to produce a non-shearing speed of the spray. Too high a spray velocity can create a negative effect on the materials making up a spray. The droplets will disintegrate at too high a velocity and not be an effective spray. They will become vapor and waste  144 , as found in many standard air assisted nozzles that create waste of 30% of the materials being sprayed. 
     The present muzzle velocity spray speed is not fast enough to create the shearing problems found with many standard supersonic spray speeds from the prior art. Thus, this nozzle doesn&#39;t need to initially eject the materials and the spray at supersonic speeds to create the spray. For this reason, it differs in method of operation from other known sprayers. Prior known spray systems depend on air velocity to be able to spray. Normally, prior art nozzles depend on a compressor that delivers an air stream with sufficient air velocity by forcing the air through a nozzle with a tiny outlet orifice. This orifice increases the air velocity and propels the spray with the high pressure air stream into the air in front of the nozzle as spray. The higher the viscosity of the sprayed material, the higher air velocity is required to spray the material. High air pressure is a preamble for producing higher velocity air streams in a standard nozzle air delivery system. A large compressor is needed with prior art systems to establish a higher velocity by generating the pressure that drives the velocity. 
     In contrast, the present spray system generates a high velocity air stream within the nozzle bore  68 . The high velocity air stream within the nozzle is converted to establish a spray. The exit speed of the combined air streams from within the nozzle  68  results in a lower spray speed that is not affected by shearing. The result is that there is no substantial waste factor. The spray nozzle has low muzzle velocity, which limits air shearing and fallout factors. The spray has a remarkably clean pattern  140 . 
     This invention employs the thermodynamics of the Gibbs free energy as well as the Plateau-Rayleigh instability phenomena by the design and assembly of the parts to produce a spray. The natural tendency of a materials flow is to break down into droplets. The nozzle forces the materials stream to pass through a radial chamber  66 , where the materials are instantly broken down into droplets by the high velocity air stream. This reaction creates a spray in the primary air chamber  66 . The invention transmits the sonic resonance backwards into the materials flowing in the passages of the nozzle, including the materials transfer tube  74 . The materials transfer tube enhances the Plateau-Rayleigh Instability by design. The materials in the conduit absorb the sonic resonance within the materials transfer tube. This enhances the materials flow break down. When the materials flow enters the chamber  66  where the four high speed air outlets are located, it has been processed by sonic resonance and can be broken up with ease. Thus the sonic resonance within the brass assembly has another benefit to this invention. 
     The nozzle  78  transforms the material flow to spray when it is hit with the four supersonic air jets  82  in the resonance chamber  66 . Combined supersonic air inlets in the nozzle create spray that leaves the nozzle at a lower spray exit speed that is subsonic in nature, of approximately 790 feet per second. The spray is leaving the nozzle at subsonic speeds. The subsonic speed is not sensitive to high air shearing. 
     The air speed inside the primary air chamber  66  is due to four air ports from passages  64  feeding 1095 ft. per sec. air, and it has an enhanced resonance level, also. The resonance levels are undetermined but exist. The nozzles ability to break up heavy thixotropic materials into spray is enhanced. The chamber is round and has four high speed air injectors in the base of the radius of the chamber. The air is radially breaking up the materials as they pass the chamber onto the nozzle&#39;s barrel by extreme air turbulence at 1095 ft. per. sec. Each port blasts the materials to droplets instantly as they pass the primary air chamber  66 . This creates the spray. 
     The spray applicator  10  is effective to deliver combustible material. This spray nozzle has been tested for delivery of fuel such as diesel fuel. The spray apparatus  10  showed an ability to function with chilled diesel fuel. The described technology may offer an improvement in fuel injectors. Particularly when delivering a combustible material of any description that may burn during spray function, the ability of the nozzle to cleanly shut off and clean itself is a great advantage as a safety measure to prevent flame from traveling back into the spray gun or to the source of the combustible material. 
     The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be regarded as falling within the scope of the invention as defined by the claims that follow.