Patent Publication Number: US-8113445-B2

Title: Spray gun having air cap with unique spray shaping features

Description:
FIELD OF INVENTION 
     The present invention relates generally to spray systems and, more particularly, to industrial spray coating systems for applying coatings of paint, stain, and the like. Specifically, the invention relates to an air cap having unique spray pattern shaping features for improving the atomization and spray pattern shape of a coating fluid. 
     BACKGROUND 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Existing spray guns typically employ a process of liquid atomization which includes generating small liquid drops from a column or sheet of fluid dispensed from a fluid orifice. The process of atomization in typical two-phase flow conditions involves the potential energy of liquid flowing from a fluid nozzle at a high velocity as a fluid stream. When the fluid stream encounters a collinear air flow around the fluid column, it undergoes primary and secondary phases of atomization. The first phase is characterized as a solid stream near the fluid nozzle. During the secondary phase of flow, atomization takes place and fluid droplets are formed. 
     These fluid droplets may be shaped using shaping air flows into specific spray patterns which are generally conical shaped. As a result, the width and/or cross-section of the spray generally increases in a linear manner from an exit of the spray gun to a target surface being coated by the spray gun. In other words, the outer profile or periphery of the spray is generally characterized by an angle that is constant relative to a centerline of the spray gun. The spray velocity also decreases with distance away from the exit of the spray gun. 
     Thus, if the spray gun is positioned relatively close to the target surface, then the spray covers a relatively small coverage portion of the target surface at a relatively high velocity. Unfortunately, the small coverage portion can increase the time to complete a spray coating process and also reduce the uniformity in the spray coating. If the velocity of the spray is too high at this close distance, then the spray may not transfer efficiently to the target surface (i.e., poor transfer efficiency). For example, the high velocity may cause the spray to bounce off of the target surface, rather than adhering to it. As a result, the poor transfer efficiency creates more waste and pollution into the environment, while it also increases the cost for coating the target surface (i.e., a greater amount of fluid is needed to coat the surface). 
     If the spray gun is positioned further away from the target surface, then the spray covers a relatively larger coverage portion of the target surface at a relatively low velocity. Unfortunately, if the velocity is too low at this greater distance, then the spray may not transfer efficiently to the target surface (i.e., poor transfer efficiency). Again, the poor transfer efficiency creates more waste and pollution into the environment, while it also increases the cost for coating the target surface (i.e., a greater amount of fluid is needed to coat the surface). 
     As a result, a typical spray gun with a conical spray is positioned at a certain distance to ensure that the velocity is not too fast or too slow. Unfortunately, the distance may result in a small coverage area, which can decrease the uniformity in the spray coating and increase the requisite time to coat the target surface. In other words, an optimal velocity results in a less than optimal coverage area, and vice versa. The typical spray gun does not provide both an optimal velocity and an optimal coverage area due to the conical shape of the spray. 
     BRIEF DESCRIPTION 
     A spray coating device, in one embodiment, is provided with a liquid passage, an air passage, one or more valves configured to open and close flow of liquid through the liquid passage and air through the air passage, a trigger coupled to the one or more valves, and a spray head configured to generate a non-conical liquid spray. The spray head includes a liquid exit in fluid communication with the liquid passage, wherein the liquid exit has a longitudinal axis of liquid flow, an air exit in fluid communication with the air passage, wherein the air exit is coaxial with the liquid exit, a first plurality of air shaping orifices in fluid communication with the air passage, wherein the first plurality of air shaping orifices have first axes that generally converge toward a first point along the longitudinal axis at first acute angles relative to the longitudinal axis, and a second plurality of air shaping orifices in fluid communication with the air passage, wherein the second plurality of air shaping orifices have second axes that generally converge toward a second point along the longitudinal axis at second acute angles relative to the longitudinal axis, the first and second acute angles are different from one another, and the first and second points are in series one after another along the longitudinal axis. A spray shaping system, in another embodiment, is provided with a first plurality of air shaping orifices having first axes directed toward a longitudinal axis of a liquid stream at first acute angles relative to the longitudinal axis, and a second plurality of air shaping orifices having second axes directed toward the longitudinal axis of the liquid stream at second acute angles relative to the longitudinal axis, wherein the first and second axes cross one another prior to reaching the longitudinal axis, the first and second acute angles are different from one another, or a combination thereof. In yet another embodiment, a spray coating system is provided with an air cap including a central atomization orifice having a longitudinal axis, a first set of air shaping orifices disposed on opposite sides of the central atomization orifice, wherein the first set of air shaping orifices are directed toward a first point along the longitudinal axis, and a second set of air shaping orifices disposed on opposite sides of the central atomization orifice, wherein the second set of air shaping orifices are directed toward a second point along the longitudinal axis, and the first and second points are in series with one another. In a further embodiment, a method of spraying a coating fluid is provided including the step of directing air streams toward a liquid stream to create a non-conical spray of the coating fluid. A spray coating device, in yet another embodiment, is provided with a body comprising liquid and air passages, and a fluid delivery tip assembly coupled to the body. The fluid delivery tip assembly includes a liquid orifice configured to output a liquid stream, an air orifice configured to output a first air stream toward the liquid stream to generate an atomized liquid spray, and a plurality of air shaping orifices configured to output air shaping streams toward the atomized liquid spray to shape the atomized liquid spray into a cup shape. 
    
    
     
       DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  is a diagram illustrating an exemplary spray coating system in accordance with certain embodiments of the present invention; 
         FIG. 2  is a flow chart illustrating an exemplary spray coating process in accordance with certain embodiments of the present invention; 
         FIG. 3  is a cross-sectional side view of an exemplary spray coating device in accordance with certain embodiments of the present invention; 
         FIG. 4  is a partial cross-sectional view of an exemplary spray tip assembly of the spray coating device of  FIG. 3  in accordance with certain embodiments of the present invention; 
         FIG. 5  is a cross-sectional view of an exemplary fluid nozzle and air cap of the spray coating device of  FIG. 3  in accordance with certain embodiments of the present invention; 
         FIG. 6A  is also a cross-sectional view of an exemplary fluid nozzle and air cap of the spray coating device of  FIG. 3  in accordance with certain embodiments of the present invention; 
         FIG. 6B  is a cross-sectional view of an embodiment of a spray pattern generated using certain embodiments of the present invention; 
         FIG. 7  is a cross-sectional view of an embodiment of a spray pattern generated using certain embodiments of the present invention; and 
         FIG. 8  is a graph illustrating exemplary particle size distribution of a spray coating device in accordance with certain embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
       FIG. 1  is a flow chart illustrating an exemplary spray coating system  10 , which comprises a spray coating device  12  for applying a desired coating to a target object  14 . As discussed in detail below, the spray coating device  12  may include unique spray shaping features configured to optimize the transfer efficiency of coating fluid to the target object  14 . For example, the spray shaping features may enable optimization of fluid velocity, spray coverage (e.g., area on the target object  14 ), uniformity of fluid distribution (e.g., uniform amount and color of fluid on the target object  14 ), fluid atomization, and so forth. By further example, the spray shaping features may enable a non-conical spray shape and/or a spray shape characterized by a width that varies in a non-linear manner (e.g., curved manner) from an exit of the device  12  to the target object  14 . In certain embodiments, the spray shape may be characterized by a cup-shaped or concave outer profile or periphery (e.g., outer edges), such that the width and/or cross-section of the spray shape is greater than a conical shape at a distance close to the exit of the spray coating device  12 . In other embodiments, the spray shape may be characterized by a tulip shaped profile or periphery. As discussed below, the unique spray shaping features may enable a greater coverage area with a suitable velocity at a distance close to the exit of the spray coating device  12 , thereby improving transfer efficiency and, thus, reducing waste and pollution. 
     It should be noted that in the context of the present disclosure, the terms “conical” and “non-conical” when used to describe a spray shape are intended to refer to the general shape of the periphery of a cross-sectional view of the spray shape. These terms are not intended to suggest that spray particles travel only along the periphery of the spray shape. Rather, spray particles may indeed be transferred throughout the entire interior space of the spray shape. 
     The illustrated spray coating device  12  may comprise an air atomizer, a rotary atomizer, an electrostatic atomizer, or any other suitable spray formation mechanism. In certain embodiments, the spray coating device  12  may be described as a spray gun, which may include a gun-shape with a handle portion, a barrel or body portion coupled to the handle portion, and a trigger to engage and disengage one or more valves. However, the unique spray shaping features may be utilized on any type of spray device. 
     The spray coating device  12  may be coupled to a variety of supply and control systems, such as a fluid supply  16 , an air supply  18 , and a control system  20 . The control system  20  facilitates control of the fluid and air supplies  16  and  18  and ensures that the spray coating device  12  provides an acceptable quality spray coating on the target object  14 . For example, the control system  20  may include an automation controller  22 , a positioning controller  24 , a fluid supply controller  26 , an air supply controller  28 , a computer system  30 , and a user interface  32 . 
     The control system  20  also may be coupled to one or more positioning mechanisms  34  and  36 . For example, the positioning mechanism  34  facilitates movement of the target object  14  relative to the spray coating device  12 . The positioning mechanism  36  is coupled to the spray coating device  12 , such that the spray coating device  12  can be moved relative to the target object  14 . Also, the system  10  can include a plurality of the spray coating devices  12  coupled to positioning mechanisms  36 , thereby providing improved coverage of the target object  14 . Accordingly, the spray coating system  10  can provide a computer-controlled mixture of coating fluid, fluid and air flow rates, and spray pattern/coverage over the target object. Depending on the particular application, the positioning mechanisms  34  and  36  may include a robotic arm, conveyor belts, and other suitable positioning mechanisms. 
       FIG. 2  is a flow chart of an exemplary spray coating process  100  for applying a desired spray coating to the target object  14 . As illustrated, the process  100  proceeds by identifying the target object  14  for application of the desired fluid (block  102 ). The process  100  then proceeds by selecting the desired fluid  40  for application to a spray surface of the target object  14  (block  104 ). The desired fluid may include a base coating fluid, a paint, a clear coat, a stain, and so forth. A user may then proceed to configure the spray coating device  12  for the identified target object  14  and selected fluid  40  (block  106 ). The target object  14  may include a vehicle, furniture, appliance, and so forth. As the user engages the spray coating device  12 , the process  100  then proceeds to create an atomized spray of the selected fluid  40  (block  108 ). In certain embodiments discussed in detail below, the atomized spray has a non-conical spray shape, such as a cup-shape, a concave shape, or a tulip shape. The user may then apply a coating of the atomized spray over the desired surface of the target object  14  (block  110 ). The process  100  then proceeds to cure/dry (e.g., infrared curing lamp) the coating applied over the desired surface (block  112 ). If an additional coating of the selected fluid  40  is desired by the user at query block  114 , then the process  100  proceeds through blocks  108 ,  110 , and  112  to provide another coating of the selected fluid  40 . If the user does not desire an additional coating of the selected fluid at query block  114 , then the process  100  proceeds to query block  116  to determine whether a coating of a new fluid is desired by the user. If the user desires a coating of a new fluid at query block  116 , then the process  100  proceeds through blocks  104 - 114  using a new selected fluid for the spray coating. If the user does not desire a coating of a new fluid at query block  116 , then the process  100  is finished at block  118 . 
       FIG. 3  is a cross-sectional side view illustrating an exemplary embodiment of the spray coating device  12 . As illustrated, the spray coating device  12  comprises a spray tip assembly  200  coupled to a body  202 . The spray tip assembly  200  includes a fluid delivery tip assembly  204 . For example, a plurality of different types of spray coating devices may be configured to receive and use the fluid delivery tip assembly  204 . The spray tip assembly  200  also includes a spray formation assembly  206  coupled to the fluid delivery tip assembly  204 . The spray formation assembly  206  comprises an air cap  208 , which is removably secured to the body  202  via a retaining nut  210 . The air cap  208  includes a variety of air atomization orifices, such as a central atomization annular orifice  212  disposed about a fluid tip exit  214  from the fluid delivery tip assembly  204 . The air cap  208  also may have one or more spray shaping orifices, such as spray shaping (e.g., air horn) orifices  216 ,  218 ,  220 , and  222 , which force the sprayed fluid to form a desired spray pattern (e.g., a non-conical pattern). The spray formation assembly  206  also may comprise a variety of other atomization mechanisms to provide a desired spray pattern and droplet distribution. 
     The body  202  of the spray coating device  12  includes a variety of controls and supply mechanisms for the spray tip assembly  200 . As illustrated, the body  202  includes a fluid delivery assembly  224  having a fluid passage  226  extending from a fluid inlet coupling  228  to the fluid delivery tip assembly  204 . The fluid delivery assembly  224  also comprises a fluid valve assembly  230  to control fluid flow through the fluid passage  226  and to the fluid delivery tip assembly  204 . The illustrated fluid valve assembly  230  has a needle valve  232  extending movably through the body  202  between the fluid delivery tip assembly  204  and a fluid valve adjuster  234 . The fluid valve adjuster  234  is rotatably adjustable against a spring  236  disposed between a rear section  238  of the needle valve  232  and an internal portion  240  of the fluid valve adjuster  234 . The needle valve  232  is also coupled to a trigger  242 , such that the needle valve  232  may be moved inwardly away from the fluid delivery tip assembly  204  as the trigger  242  is rotated counter clockwise about a pivot joint  244 . However, any suitable inwardly or outwardly openable valve assembly may be used with embodiments of the present invention. The fluid valve assembly  230  also may include a variety of packing and seal assemblies, such as packing assembly  246 , disposed between the needle valve  232  and the body  202 . 
     An air supply assembly  248  is also disposed in the body  202  to facilitate atomization at the spray formation assembly  206 . The illustrated air supply assembly  248  extends from an air inlet coupling  250  to the air cap  208  via air passages  252  and  254 . The air supply assembly  248  also includes a variety of seal assemblies, air valve assemblies, and air valve adjusters to maintain and regulate the air pressure and flow through the spray coating device  12 . For example, the illustrated air supply assembly  248  includes an air valve assembly  256  coupled to the trigger  242 , such that rotation of the trigger  242  about the pivot joint  244  opens the air valve assembly  256  to allow air flow from the air passage  252  to the air passage  254 . The air supply assembly  248  also includes an air valve adjustor  258  coupled to a needle  260 , such that the needle  260  is movable via rotation of the air valve adjustor  258  to regulate the air flow to the air cap  208 . As illustrated, the trigger  242  is coupled to both the fluid valve assembly  230  and the air valve assembly  256 , such that fluid and air simultaneously flow to the spray tip assembly  200  as the trigger  242  is pulled toward a handle  262  of the body  202 . Once engaged, the spray coating device  12  produces an atomized spray with a desired spray pattern (e.g., non-conical) and droplet distribution. Again, the illustrated spray coating device  12  is only an exemplary embodiment of the present invention. Any suitable type or configuration of a spraying device may benefit from the unique air cap fluid atomization and air shaping aspects of the present invention. 
       FIG. 4  is a partial cross-sectional view of the spray tip assembly  200  of the spray coating device  12  of  FIG. 3  in accordance with certain embodiments of the present invention. As illustrated, the needle  260  of the air supply assembly  248  and the needle valve  232  of the fluid valve assembly  230  are both open, such that air and fluid passes through the spray tip assembly  200  as indicated by the arrows. Turning first to the air supply assembly  248 , the air flows through air passage  254  about the needle  260  as indicated by arrow  300 . The air then flows from the body  202  and into a central air passage  302  through a fluid nozzle  304 , as indicated by arrows  306 . The central air passage  302  then splits into outer and inner air passages  308  and  310  of the air cap  208 , such that the air flows as indicated by arrows  312  and  314 , respectively. 
     The outer passages  308  then connect with the shaping air horn orifices  216 ,  218 ,  220 , and  222 , such that air flows inwardly toward a longitudinal axis  316  of the spray tip assembly  200 . These spray shaping air flows are illustrated by arrows  318 ,  320 ,  322 , and  324 . As illustrated, these spray shaping air flows are angled at acute angles (e.g., between 0 and 90 degrees) relative to the longitudinal axis  316 . In the illustrated embodiment, the angles are between about 20-70 degrees, or 30-60 degrees, or 40-50 degrees. However, any suitable angle may be used to enable a desired non-conical shape of the forming spray. 
     The inner passages  310  surround the fluid delivery tip assembly  204  and extend to the central atomization annular orifice  212 , which is positioned about (e.g., coaxial or concentric with) the fluid tip exit  214  of the fluid delivery tip assembly  204 . This central atomization annular orifice  212  discharges atomizing air streams generally parallel to the longitudinal axis  316 , as indicated by arrows  326 . In the illustrated embodiment, the central atomization annular orifice  212  is configured to provide the primary force to atomize the fluid exiting the fluid tip exit  214 . 
     In summary, these air flows  318 ,  320 ,  322 ,  324 , and  326  are all directed toward a fluid flow  328  discharged from the fluid tip exit  214  of the fluid delivery tip assembly  204 . In operation, these air flows  318 ,  320 ,  322 ,  324 , and  326  facilitate fluid atomization to form a fluid spray and, also, shape the fluid spray into a desired pattern (e.g., non-conical). As discussed below, the air flows  318 ,  320 ,  322 ,  324 , and  326  may be configured or oriented to shape the spray in a non-conical shape, such as a cup shape, a concave shape, or a tulip shape. 
       FIG. 5  is a cross-sectional view of an exemplary fluid nozzle  304  and air cap  208  of the spray coating device  12  of  FIG. 3  in accordance with certain embodiments of the present invention. In particular,  FIG. 5  illustrates interaction of the air cap  208  with the fluid nozzle  304  of the spray coating device  12  with respect to both atomization and shaping of the fluid stream. For example, as discussed above, the fluid flow  328  may be directed through the fluid nozzle  304  toward the fluid tip exit  214 . The atomization air may flow through a reservoir chamber  402  formed between the fluid nozzle  304  and the air cap  208  toward the central atomization annular orifice  212  where the atomization air is discharged. 
     The reservoir chamber  402  (e.g., annular chamber) is formed by a lip  404  which extends generally perpendicular from an inner wall  406  of the air cap  208 . This lip  404 , and resulting reservoir chamber  402 , naturally creates a reservoir effect upstream of the central atomization annular orifice  212 , as opposed to allowing the atomization air to flow unimpeded to and through the central atomization annular orifice  212 . This reservoir effect is beneficial in that the atomization air flow is allowed to stabilize by filling and pressurizing the reservoir chamber  402  before proceeding to the central atomization annular orifice  212 . As such, the atomization air flow may be much more laminar by the time it reaches the central atomization annular orifice  212 . This may have the effect of optimizing particle distribution. For instance, if the atomization air were allowed to continue unimpeded to the central atomization annular orifice  212 , the turbulent air flow may cause more of an explosive, splattering effect on the particle distribution. However, allowing for a more laminar flow without pressure pulses and with uniform pressure distribution may generate a smoother, more controllable fluid atomization and result in more uniform distribution of fluid particles. In addition, allowing for more laminar flow of the atomization air with uniform pressure distribution helps ensure that the supply of atomization air is never depleted and there is continual back pressure behind the flow of atomization air. 
     The specific design of the lip  404 , inner wall  406 , and resulting reservoir chamber  402  may vary depending on not only the design of the air cap  208  but on the design of the fluid nozzle  304  as well. For example, the fluid nozzle  304  and the air cap  208  may be designed such that not only a reservoir chamber  402  is formed, but that the lip  404  functions as an impedance to the flow of atomization air. In addition, the fluid nozzle  304  and air cap  208  may be designed in conjunction to allow for an appropriately sized atomization channel  408  between the reservoir chamber  402  and the central atomization annular orifice  212 . Furthermore, the manner in which the atomization air reaches the reservoir chamber  402  may vary depending on the particular designs of the fluid nozzle  304  and air cap  208 . For instance, in the illustrated embodiment, the atomization air reaches the reservoir chamber  402  by moving through the fluid nozzle  304 . However, alternative embodiments may allow for the atomization air to reach the reservoir chamber  402  by moving through a passageway created between the fluid nozzle  304  and air cap  208 . 
     In addition, a portion of the atomization air may also be discharged through at least one pair of central air shaping orifices  410  before reaching the central atomization annular orifice  212 . The shaping air flow includes multiple functions. First, this central shaping air may help prevent fluid from the fluid flow  328  from depositing on the interior face of the air cap  208 . Second, this central shaping air may help direct the fluid flow toward the target object  14 . In the illustrated embodiment, the central air shaping orifices  410  are aligned at a slight angle toward the longitudinal axis  316 . For example, the slight angle may be less than 20 degrees, less than 15 degrees, less than 10 degrees, or less than 5 degrees relative to the longitudinal axis  316 . However, in alternate embodiments, the central air shaping orifices  410  may be aligned parallel to the longitudinal axis  316 . 
     Other shaping air streams may flow through two shaping air horn passages  412 ,  414  residing within two shaping air horns  416 ,  418  which protrude from opposite sides of the circular outer face of the air cap  208 . The shaping air in the shaping air horn passages  412  and  414  exits via shaping air horn orifices  216 ,  220  and  218 ,  222 , respectively, forming shaping air streams  318 ,  320 ,  322 , and  324 . These shaping air streams  318 ,  320 ,  322 , and  324  aid in generating the desired spray pattern (e.g., non-conical) of fluid. 
     In the illustrated embodiment, the pairs of shaping air streams (e.g.,  318 ,  320  and  322 ,  324 ) are generally not parallel to one another. Instead, the outer shaping air streams  318 ,  320  are directed toward the longitudinal axis  316  of the air cap  208  at a slightly wider angle than their respective inner shaping air stream pairs  322 ,  324 . For example, the angle between the streams  318 ,  320  and the adjacent streams  322 ,  324  may be less than 30 degrees, less than 25 degrees, less than 20 degrees, less than 15 degrees, less than 10 degrees, or less than 5 degrees. These angles between streams is a result of angles between the axes of the outer shaping air horn orifices  216 ,  218  and their respective inner shaping air horn orifices  220 ,  222 . Specifically, the orifices  216 ,  218  are directed toward the longitudinal axis  316  of the air cap  208  at a slightly wider angle than the respective orifices  220 ,  222 . For example, each axis of the outer shaping air horn orifices  216 ,  218  may form an angle with the longitudinal axis  316  of the air cap  208  of between 60 and 75 degrees, whereas each axis of the inner shaping air horn orifices  220 ,  222  may form an angle with the longitudinal axis  316  of the air cap  208  of between 45 and 60 degrees. In fact, due to the specific configuration of the outer air horn orifices  216 ,  218  and inner air horn orifices  220 , and  222 , the outer shaping air streams  318 ,  320  actually intersect their respective inner shaping air streams  322 ,  324  before intersecting the fluid flow  328  along the longitudinal axis  316  of the air cap  208  (at points  420  and  422 , respectively). Thus, the streams  322 ,  324  criss-cross, cross over one another, or generally pass in crosswise paths relative to one another. 
     In the illustrated embodiment, the crosswise paths of the streams  318 ,  320  and the streams  322 ,  324  help generate the non-conical spray pattern, as discussed in greater detail below.  FIG. 6A  illustrates an exemplary embodiment of the spray tip assembly  200 , illustrating the criss-crossing configuration of the shaping air streams  318 ,  320 ,  322 ,  324  facilitating shaping of the fluid flow  328  in a non-conical spray pattern. As the fluid flow  328  exits the fluid tip exit  214 , it generally follows the path of the atomizing air streams  326 , which generally form an annular shape around the fluid flow  328 . The atomizing air streams  326  begin to atomize the fluid flow  328  at some point  502  before crossing the shaping air streams  318 ,  320 ,  322 ,  324 . The atomized fluid flow  328  eventually crosses the path of the outer shaping air streams  318 ,  320 . This point may be called a first impingement point  504 . At this first impingement point  504 , the atomized fluid flow  328  may begin forming a conical spray pattern and the fluid velocity of the atomized fluid flow  328  may be slightly decreased. Then, downstream of the first impingement point  504 , the atomized fluid flow  328  crosses the path of the inner shaping air streams  322 ,  324 . This point may be called a second impingement point  506 . At this second impingement point  506 , the fluid velocity of the atomized fluid flow  328  is further slowed and a non-conical spray pattern is formed. 
       FIG. 6B  is a cross-sectional view of the non-conical spray pattern generated using certain embodiments of the present invention.  FIG. 6B  further illustrates the effects of the first and second impingement points  504 ,  506  on the atomized fluid flow  328 . In other embodiments, more than two sets of shaping air streams may be used such that more than two impingement points are generated. Using more than two shaping air streams in this manner may lead to even greater spray pattern shaping results. For instance, a third set of shaping air steams generating a third impingement point may lead to a more stabilized spray pattern or even different spray pattern shapes, depending on the particular configuration of the shaping air orifices. In addition, in other embodiments, the shaping air orifices may be aligned such that the shaping air streams do not actually intersect each other or the fluid flow  328 . Aligning the shaping air streams in this manner may lead to generally similar spray pattern shapes but may also generate swirling effects that may prove beneficial with respect to particle velocity and distribution. 
     The non-conical spray pattern may exhibit numerous advantages over the conical spray patterns typically generated by existing air caps.  FIG. 7  again shows a cross-sectional view of the spray pattern generated using certain embodiments of the present invention.  FIG. 7  illustrates the differences between a conical spray pattern  602  and a non-conical spray pattern  604 . As illustrated in  FIG. 7 , the non-conical spray pattern  604  generally defines a wider approach toward a target object  14  than the conical spray pattern  602 . As such, the resulting fan pattern is generally wider for the non-conical spray pattern  604  than for the conical spray pattern  602  at many of the spray distances from the target object  14  (e.g., particularly at distances close to the spray coating device  12 ). For instance, at some distance of D 1 , both the non-conical spray pattern  604  and the conical spray pattern  602  will generate fan patterns having the same width of W 1 . However, as the spray coating device  12  is moved closer to the target object  14 , the fan pattern resulting from the non-conical spray pattern  604  becomes progressively wider than the fan pattern resulting from the conical spray pattern  602 . For instance, at some distance D 2  which is closer than distance D 1 , the resulting width W 2  of the fan pattern generated by the non-conical spray pattern  604  is greater than the resulting width W 2  of the fan pattern generated by the conical spray pattern  602 . This trend will continue until some distance, illustrated in  FIG. 7  as D 3 , where the resulting fan pattern generated by the non-conical spray pattern  604  will gradually begin getting closer to that of the fan pattern generated by the conical spray pattern  602 . 
     Therefore, the non-conical spray pattern  604  may generally lead to more consistent fan pattern widths regardless of the distance of the spray coating device  12  from the target object  14 . For example, the conical spray pattern  602  may generally require a distance of 8-10 inches between the spray coating device  12  and the target object  14  in order to maintain a consistent fan pattern width. In contrast, the non-conical spray patterns  604  may reduce variations in the fan pattern width over a greater range of distances between the spray coating device  12  and the target object  14 , thereby enabling a more consistent fan pattern despite the distance. Furthermore, the non-conical spray pattern  604  may enable positioning at much closer or farther distances between the spray coating device  12  and the target object  14 , thereby enabling better optimization of both the fluid velocity and the fan pattern width. For example, the spray coating device  12  may be positioned at 5-6 inches or 12-14 inches rather than 8-10 inches from the target object  14 , thereby improving the transfer efficiency due to a more appropriate fluid velocity along with a suitably large fan pattern width. These distances are merely illustrative but they do show some advantages to the non-conical spray pattern  604  versus the conical spray pattern  602 . For instance, as mentioned above, resulting fan pattern widths may generally be more consistent with the non-conical spray pattern  604 . In addition, there may not be as great of a need to hold the spray coating device  12  at a certain distance from the target object  14  to generate a consistent fan pattern with the non-conical spray pattern  604 . 
     Furthermore, due to the dual air stream impingement, the fluid velocity of the atomized fluid flow  328  is substantially reduced. Subsequently, when the slower velocity atomized fluid/air fan pattern is deposited onto a sprayed target object  14 , a reflective force of the fan pattern from the target object  14  is minimized, causing most of the fluid particles to be deposited onto the surface of the target object  14 . In other words, as a result of the reduced fluid velocity, a greater amount of the fluid is transferred to the target object  14  (e.g., increased transfer efficiency). Existing spray coating devices (with conical spray patterns) have poor transfer efficiency at distances closer to the spray tip exit, because the fluid velocity is too high and the spray pattern width is too small. In contrast, the disclosed embodiments both decrease the fluid velocity and increase the spray pattern width (or general coverage area) at closer distances to the spray tip exit. As a result, the spray coating device  12  can be positioned over a larger range of distances relative to the target object  14 , thereby enabling optimization of the fluid velocity while maintaining a suitably wide spray pattern. In addition, the disclosed embodiments allow for a more uniform distribution along the entire fan pattern. This is partially due to the fact that the fluid velocity is substantially reduced toward the periphery of the spray pattern. However, it is also partially due to the fact that the spray particles in non-conical spray patterns may approach the target objects  14  at substantially perpendicular angles as opposed to the angled approach typical in conical spray patterns. 
     Preliminary test results have proven that embodiments of the present invention may provide numerous benefits over other existing air caps. For example, as illustrated by  FIG. 8 , one particular test showed that the particle size distribution over a particular pattern width was substantially uniform at various flow rates. Particle size is typically expressed in various methods found in ASTM standard E1620-97. For testing purposes, D32 Sauter Mean Diameter or SMD32 was used. The Sauter Mean Diameter (SMD) is defined as the diameter of a sphere that has the same volume/surface area ratio as a particle of interest. The SMD is a common measure in fluid dynamics as a way estimating average particle size. Calculation is usually taken as the mean of several measurements or samples. The measurement of particles in the testing was performed via flux distribution techniques using a Malvern particle size analyzer. Flux measurement is recorded by optical instrumentation that is capable of measuring individual drop sizes. 
     In a typical spray gun of the prior art, the fluid stream begins to form atomized droplets at a distance of 5-10 mm from the fluid nozzle tip. At this point, the velocity of combined air and fluid stream is extremely high. These velocities are very impractical in spray applications and must be substantially decreased to much lower velocities to be usable for spray finishing applications. Typical atomized patterns of the prior art, when formed with shaping air jets, continue at these very high velocities in a range of 10-30 meters/second at 8 inches from the fluid nozzle. These higher spray velocities may cause paint overspray, lower paint transfer efficiencies, and subsequent waste of costly paint. 
     A certain balance of collinear air flow velocity and air pressure around the fluid stream plays a key role as to how big or small the particle sizes become using the techniques of the disclosed embodiments. In addition, the particle distribution uniformity within the shape of the fan pattern is significantly influenced by precise positioning of shaping air impingement points into the atomized fluid stream. A substantial velocity reduction down to 5 meters/second and a wide pattern up to 12 inches was achieved during testing with the precise positioning of shaping air horn jets as described in detail above. In addition, the tulip-shaped pattern was formed with very uniform pattern particle distribution. 
     Particle size and particle distribution within the spray pattern is an important factor in overall performance of the fluid nozzle and air cap combination of the disclosed embodiments. Specifically, spray particle distribution uniformity plays an important role in achieving adequate paint distribution on the substrate of the target object and subsequently good finish quality. An added benefit of the lower velocity spray fan pattern may be minimum “overspray” bounce back from the substrate being coated. 
     In contrast to the results of the testing, most prior art high-velocity, low pressure (HVLP) air caps exhibit larger particle concentration on the edges of the fan pattern. In addition, the maximum fan pattern size generated by the disclosed embodiments has been shown to be considerably larger (e.g., up to 15 inches or more) than those generated by other air caps. Also, as mentioned above, the lower velocities generated by the disclosed embodiments generally allow for minimum bounce back of fluid particles. For example, the disclosed embodiments have been shown to produce acceptable atomization quality using air velocities as low as 5 meters/second, as opposed to typical HVLP air caps which can sometimes require air velocities of 12-18 meters/second. This, of course, also indirectly leads to lower overall fluid and air consumption. 
     Therefore, the disclosed embodiments provide low air consumption, low air velocities, and consistently uniform spray patterns, which, in turn, lead to uniform spray quality and less waste. As mentioned above, unlike typical air caps, the disclosed embodiments generate a non-conical spray pattern allowing the spray coating device  12  to achieve larger fan pattern size when spraying close to the surface. A unique characteristic of the disclosed embodiments is that it is able to atomize spray coatings at HVLP application levels, which range from 0 to 10 psi air at the air cap, but it can also atomize spray coatings successfully at low volume, medium pressure (LVMP) levels between 10 and 30 psi levels. 
     While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.