Patent Grant
11027295
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.
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.
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:
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
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
The spray applicator assembly 10 has a forward handle 40,
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
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'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
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'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'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
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's eye.” The user typically tries to hide the bull'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
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,
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,
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
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
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
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.
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'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,
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'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'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.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4174068 | Rudolph | Nov 1979 | A |
| 4951876 | Mills | Aug 1990 | A |
| 5536531 | Owen | Jul 1996 | A |
| 6095435 | Greer, Jr. et al. | Aug 2000 | A |
| 6161778 | Haruch | Dec 2000 | A |
| 7163130 | Lafond | Jan 2007 | B2 |
| 8028934 | Wurz | Oct 2011 | B2 |
| Number | Date | Country | |
|---|---|---|---|
| 20190076861 A1 | Mar 2019 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62555871 | Sep 2017 | US |
