Patent Publication Number: US-2015060579-A1

Title: Electrostatic Spray System

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This Application is a Non-Provisional Application and claims priority to U.S. Provisional Patent Application No. 61/871,741, entitled “Electrostatic Spray System”, filed Aug. 29, 2013, which is herein incorporated by reference. 
    
    
     BACKGROUND 
     The invention relates generally to an electrostatic spray system. 
     Electrostatic tools spray electrically charged materials to more efficiently coat objects. For example, electrostatic tools may be used to paint objects. In operation, a grounded target attracts electrically charged materials sprayed from an electrostatic tool. As the electrically charged material contacts the grounded target, the material loses the electrical charge. 
     BRIEF DESCRIPTION 
     Certain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below. 
     In one embodiment, a system including an electrostatic spray system, including a handheld spray coating device, a rotary atomizer coupled to the handheld spray coating device, wherein the rotary atomizer atomizes a liquid flowing through the handheld spray coating device, and an indirect charging device coupled to the handheld spray coating device, wherein the indirect charging device is configured to electrostatically charge the liquid exiting the rotary atomizer. 
     In another embodiment, a system including an indirect charging system configured to electrostatically charge a liquid sprayed from a handheld spray coating device with a rotary atomizer, wherein the indirect charging device system includes a non-conductive casing configured to couple to the handheld spray coating device, and a power supply coupled to the non-conductive casing, wherein the power supply enables electrostatic charging of the liquid passing through the non-conductive casing. 
     In another embodiment, a system including an electrostatic spray system, including a spray coating device, an atomizer coupled to the spray coating device, wherein the atomizer is configured to atomize a liquid flowing through the spray coating device, an indirect charging device, including a non-conductive casing downstream and radially offset from the atomizer, and a power supply coupled to the non-conductive casing, wherein the indirect charging device electrostatically charges the liquid exiting the atomizer. 
    
    
     
       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 cross-sectional side view of an embodiment of a spray coating device; 
         FIG. 2  is a cross-sectional side view of an embodiment of an indirect charging device coupled to a rotary atomizer; 
         FIG. 3  is a cross-sectional side view of an embodiment of an indirect charging device; 
         FIG. 4  is a cross-sectional side view of an embodiment of an indirect charging device; 
         FIG. 5  is a cross-sectional side view of an embodiment of an indirect charging device; 
         FIG. 6  is a cross-sectional side view of an embodiment of an indirect charging device; and 
         FIG. 7  is a cross-sectional side view of an embodiment of an indirect charging device. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present disclosure 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. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters and/or environmental conditions are not exclusive of other parameters/conditions of the disclosed embodiments. 
     The present disclosure is generally directed to an electrostatic spray system that indirectly charges a fluid that is atomized and sprayed by a handheld spray gun. More specifically, the system includes an indirect charging device that electrically charges a fluid that is atomized by a rotary atomizer The indirect charging device may include a high voltage power supply, a conductive member (e.g., a wire), and a non-conductive casing member coupled to the rotary atomizer. In operation, the high voltage power supply supplies a high voltage current that flows through the conductive member attached to the non-conductive casing. As the high voltage current flows through the conductive member, the high voltage current produces a magnetic field enabling indirect electrical charging of the atomized fluid passing through the non-conductive casing. In one embodiment, the conductive member may couple to an end of the non-conductive casing to charge the atomized fluid as the atomized fluid exits the non-conductive casing. In some embodiments, the conductive member may wrap around an interior surface of the non-conductive housing charging the atomized fluid before the atomized fluid exits the non-conductive casing. In another embodiment, there may be multiple conductive members coupled to the power supply and that receive differing amounts of current and voltage. In still another embodiment, the indirect charging device may include a conductive casing coupled to the non-conductive casing and that receives high voltage current from the power supply to indirectly charge the fluid. 
       FIG. 1  is a cross-sectional side view illustrating an embodiment of an electrostatic spray system  10  that includes a handheld spray coating device  12  (e.g., a gun), a rotary atomizer  14 , and an indirect charging device  16 . As illustrated, the handheld spray coating device  12  includes a body  18  that enables the rotary atomizer  14  and the indirect charging device  16  to couple to the handheld spray coating device  12 . In operation, the indirect charging device  16  enables electrostatic charging of a fluid (e.g., liquid coating material) that is atomized by the rotary atomizer  14  to facilitate spraying a target or object. In some embodiments, the indirect charging device  16  enables electrostatic charging when using spray formation mechanisms other than a rotary atomizer  14 , such as an air cap that facilitates pneumatic atomization of the fluid (e.g., liquid coating material). 
     The body  18  of the spray coating device  12  includes a variety of controls and supply mechanisms for the rotary atomizer  14 . As illustrated, the body  18  includes a fluid delivery assembly  20  having a fluid passage  22  extending from a fluid inlet coupling  24  through the rotary atomizer  14 . The fluid inlet coupling  24  enables attachment of a conduit  26  that delivers liquid material from the material source  28  to the rotary atomizer  14 , through the fluid passage  22 . To control fluid flow to the rotary atomizer  14 , the spray coating device  12  includes a fluid valve assembly  30 . The fluid valve assembly  30  has a needle valve  32  extending movably through the body  18  between the rotary atomizer  14  and a valve adjuster  34 . In certain embodiments, the valve adjuster  34  may be rotatably adjustable against a spring  36  disposed between a rear section  38  of the needle valve  32  and an internal portion  40  of the valve adjuster  34 . 
     The needle valve  32  is also coupled to a trigger  42 , such that the needle valve  32  may be moved inwardly, in direction  44  away from the rotary atomizer  14 , as the trigger  42  is rotated in a counter clockwise direction  46  about a pivot joint  46 . However, any suitable inwardly or outwardly openable valve assembly may be used within the scope of the present embodiments. As the needle valve  32  moves inwardly away from the rotary atomizer  14 , the needle valve  32  unseats (i.e., opens) enabling fluid to flow through the fluid passage  22  and into the rotary atomizer  14 . More specifically, in some embodiments, the fluid flowing through the fluid passage  22  may be pressure fed, so that when the needle valve  32  moves away from the fluid tip exit  30 , the pressure induces the fluid to enter the rotary atomizer  14 . In certain embodiments, the fluid valve assembly  30  may also include a variety of packing and seal assemblies, such as packing assembly  48 , disposed between the needle valve  32  and the body  16 . 
     An air supply assembly  50  is also disposed in the body  16  to facilitate atomization at the spray formation assembly  22 . Specifically, the rotary atomizer  14  may include an air driven motor  52  that drives the rotary atomizer for atomization of the fluid. The illustrated air supply assembly  50  extends from an air inlet coupling  54  to the rotary atomizer  14  via air passages  56  and  58 . The air supply assembly  50  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  50  includes an air valve assembly  60  coupled to the trigger  42 , such that rotation of the trigger  42  about the pivot joint  56 , in direction  46 , opens the air valve assembly  60  to allow airflow from the air passage  56  to the air passage  58 . The air supply assembly  50  also includes an air valve adjustor  62  coupled to a needle  64 , such that the needle  64  is movable via rotation of the air valve adjustor  62  to regulate the air flow to the air motor  52  within the rotary atomizer  14 . As illustrated, the trigger  42  is coupled to both the fluid valve assembly  30  and the air valve assembly  60 , such that the fluid and air simultaneously flow to the rotary atomizer  14  as the trigger  42  is pulled toward a handle  66  of the body  16 . Once engaged, the spray coating device  12  produces an electrically charged atomized spray with a desired spray pattern and droplet distribution. As further illustrated, an air conduit  68  is coupled to the air inlet coupling  54  and the air source  70  enabling airflow from the air source  70  into the spray coating device  12  during operation. 
     As mentioned above, the handheld spray gun  12  includes an indirect charging device  16  that enables electrostatic charging of a fluid atomized by the rotary atomizer  14 . The indirect charging device  16  includes a power supply  72 , a non-conductive casing or wall  74 , and a conductive member  76 . As illustrated, the non-conductive casing or wall  74  (e.g., an annular wall, a conical wall, a curved annular wall, a diverging wall, or any combination thereof) attaches to the rotary atomizer  14  and forms a funnel with a first end  78 , a second end  80 , and a fluid passage  82  between the first end  78  and the second end  80 . In some embodiments, the non-conductive casing  74  may be elliptically shaped, bell shaped, conical shaped, parabolically shaped, generally diverging, generally cylindrical, square, rectangular, etc. Moreover in some embodiments, the non-conductive casing  74  may be integrally coupled to the rotary atomizer  14 . In operation, the rotary atomizer  14  atomizes the fluid that passes through the non-conductive casing  74  in direction  79 . As the fluid passes through the non-conductive casing  74 , a magnetic field created by a high voltage current carried in the conductive member  76  indirectly charges (i.e., ionizes) the fluid. The conductive member  76  electrically couples to the power supply  72  with the electric line  84 . The power supply  72  generates the high voltage current with a power source  86  and a cascade voltage multiplier  88 . In operation, the power source  86  provides the electric current, while the cascade voltage multiplier  88  increases the voltage. 
       FIG. 2  is a cross-sectional side view of an embodiment of a rotary atomizer  14  surrounded by the non-conductive member  74 . As explained above, the rotary atomizer  14  enables the spray coating device  12  to atomize a fluid  108  for spraying. In some embodiments, the rotary atomizer  14  may be a bell-shaped rotary atomizer that receives the fluid  108  from the fluid delivery assembly  20  through the fluid passage  22 . As the fluid  108  flows through the fluid passage  22 , the fluid  108  enters a rotary bell cup  110  where the fluid  108  contacts an impingement plate  112 . The bell cup  110  may be a conical bell cup, a parabolic bell cup, a generally curved annular bell cup, or a diverging annular bell cup. The plate  112  redirects the fluid  108  radially outward and towards the interior surface  114  of the bell cup  110 . As the bell cup  110  rotates about the axis  116 , the fluid  108  flows along the interior surface  114  of the bell cup  110 . For example, the centrifugal force of the rotating bell cup  110  forces the fluid to flow directly along the internal surface  114 , in a downstream direction axially toward the edge  118 . When the fluid  108  reaches the edge  118 , (e.g., outer annular edge) the rotation of the bell cup  110  shears the fluid  108 . In other words, the rotary atomizer  14  atomizes the fluid  108  as the fluid  108  shears off the edge  118  of the bell cup  110 . After exiting the bell cup  110 , the fluid  108  enters the fluid passage  82  in the non-conductive casing  74 . As illustrated, the bell cup  110  is rotary and the non-conductive casing  74  is stationary and offset (e.g., radially offset) from the bell cup  110 . As the fluid  108  passes through and exits the non-conductive casing  74 , the fluid  108  is indirectly charged or ionized in a magnetic field  120 . As explained above, the indirect charging device  16  forms the magnetic field  120  as high voltage current, supplied by the power supply  72 , passes through the conductive member  76 . 
       FIG. 3  is a cross-sectional side view of an embodiment of an indirect charging device  16 . As illustrated, the indirect charging device  16  includes the power supply  72  that supplies a high voltage current to indirectly charge an atomized fluid. The power supply  72  couples to a conductive member  76  (e.g., a wire) that then carries the high voltage current in the indirect charging device  16 . The conductive member  76  enters the non-conductive casing  74  through an aperture  140  in the side wall  142 . After passing through the aperture  140 , the conductive member  76  may couple to the interior surface  144  and wind back and forth between the first end  78  and the second end  80  along the fluid passage  82 . In operation the conductive member  76  enables high voltage current from the power supply  72  to form a magnetic field that indirectly charges or ionizes the atomized fluid passing through the fluid passage  82 . As illustrated, the conductive member  76  is generally parallel to the non-conductive member  74  as the conductive member  76  winds back and forth between the first end  78  and the second end  80 . However in some embodiments, the conductive member  76  may not wind back and forth between the first end  78  and the second end  80 , but instead wind back and forth a fraction of the distance between the first end  78  and the second end  80  (e.g., 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 percent). In embodiments where the conductive member  76  winds back and forth a fraction of the distance between the first end  78  and the second end  80 , the conductive member  76  may be closer to either the first end  76  or the second end  78 . Furthermore, some embodiments may include different amounts of windings  146  within the non-conductive member  74 . For example, some embodiments may include more windings  146 , with correspondingly less space between the windings  146 , while other embodiments have fewer windings  146  that are then spaced further apart. 
       FIG. 4  is a cross-sectional side view of an embodiment of an indirect charging device  16 . The indirect charging device  16  is similar to the indirect charging device shown in  FIG. 3  and discussed above. However, the orientation of the conductive member  76  in the indirect charging device  16  of  FIG. 4  is generally perpendicular to the non-conductive casing  74  (e.g., perpendicular or crosswise to axis  116 ). As illustrated, the conductive member  76  spirals crosswise (e.g., perpendicular to the axis  116 ) between the first end  78  and the second end  80  along the interior surface  144  of the non-conductive casing  74 . However, in some embodiments, conductive member  76  may spiral a fraction of the distance between the first end  78  and the second end  80  (e.g., 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 percent). In embodiments where the conductive member  76  spirals a fraction of the distance between the first end  78  and the second end  80 , the conductive member  76  may be closer to either the first end  76  or the second end  78 . Furthermore, in some embodiments the conductive member  76  may form a spiral that becomes more compact between the first end  78  and the second end  80  of the non-conductive casing  74 . For example, the conductive member  76  may form a spiral that increases in density near the second end  80  of the non-conductive casing  74 . 
       FIG. 5  is a cross-sectional side view of an embodiment of an indirect charging device  16 . As illustrated, the indirect charging device  16  includes conductive members  76 ,  170 ,  172 , and  174  (e.g., annular conductive members) that coupled to the power supply  72 . Furthermore, each of the conductive members  76 ,  170 ,  172 , and  174  couples to the non-conductive housing  74  enabling the indirect charging device  16  to form a magnetic field(s) that charge an atomized fluid passing through the fluid passage  82 . In some embodiments, the indirect charging device  16  may include less than or more than four conductive elements (e.g., 1, 2, 3, 4, 5, 10, 15, 20 or more separate conductive elements). As illustrated, conductive members  76 ,  170 , and  172  pass through the side wall  142  and couple to the interior surface  144  of the non-conductive casing  74 , while the conductive member  174  couples to the second end  80  of the non-conductive casing  74 . As illustrated, the conductive members  76 ,  170 ,  172 , and  174  are approximately equal distant apart from one another along the length of the non-conductive casing  74 . However, in some embodiments, the conductive members  76 ,  170 ,  172 , and  174  may be closer together near the first end  78  or the second end  80 . In other embodiments, the indirect charging device  16  may vary the spacing between the conductive members  76 ,  170 ,  172 , and  174 . 
     In operation, the indirect charging device  16  may use the conductive members  76 ,  170 ,  172 , and  174  in different ways to indirectly charge the atomized fluid. For example, the power supply  72  may supply different amounts of current and voltage to each of the conductive members  76 ,  170 ,  172 , and  174  (e.g., progressively increase, progressively decrease, or alternate current flow and voltage between the conductive members). The indirect charging device  16  may also enable a user to turn off some of the conductive members  76 ,  170 ,  172 , and  174  depending on the application. Furthermore, in some embodiments, the  76 ,  170 ,  172 , and  174  may be embedded in the interior surface  144  of the non-conductive casing  74 . As illustrated, conductive member  172  embeds within a recess  176  (e.g., annular recess) in the non-conductive casing  74  reducing possible contact between the atomized fluid and the conductive member  172 . 
       FIG. 6  is a cross-sectional side view of an embodiment of an indirect charging device  16  that includes a conductive casing  200  coupled to the non-conductive casing  74 . The casings  74  and  200  may be conical casings, parabolic casings, cylindrical casings, diverging annular casings, or any combination thereof. The conductive casing  200  includes a first end  202 , a second end  204 , an exterior surface  206 , an interior surface  208 , and an aperture  210  between the first end  202  and the second end  204 . As illustrated, the first end  202  of the conductive casing  200  couples to the second end  80  of the non-conductive casing  74 . The coupling between the conductive casing  200  and the non-conductive casing  74  maybe a snap-fit connection, a friction fit connection, a threaded connection, or a bolted connection. The conductive casing  200  electrically couples to and receives high voltage current from the power supply  72  with the electric line  84 . In operation, the power supply  72  supplies a high voltage current to the conductive casing  200  that indirectly charges the atomized fluid. More specifically, as high voltage electric current flows through the conductive casing  200  the high voltage current creates a magnetic field that indirectly charges/ionizes the atomized fluid passing through the aperture  210 . 
       FIG. 7  is a cross-sectional side view of an embodiment of an indirect charging device  16  that includes a conductive casing  200  coupled to the non-conductive casing  74 . As illustrated, the conductive casing  200  and the non-conductive casing  74  may have curved annular bell shapes. However, in some embodiments, the conductive casing  200  and/or the non-conductive casing  74  may have another shape (e.g., cylindrically shaped, parabolic shaped, elliptically shaped, square shaped, rectangular shaped, or a truncated conical shape). For example, the non-conductive casing  74  may be a truncated conical shape, while the conductive casing  200  is cylindrical, or vice versa. In the illustrated embodiment, the non-conductive casing  74  and the conductive casing  200  both define curved annular bell shapes. 
     As explained above, the first end  202  of the conductive casing  200  couples to the second end  80  of the non-conductive casing  74 . The coupling between the conductive casing  200  and the non-conductive casing  74  maybe a snap-fit connection, a friction fit connection, a threaded connection, or a bolted connection. The conductive casing  200  electrically couples to and receives high voltage current from the power supply  72  with the electric line  84 . In operation, the power supply  72  supplies a high voltage current to the conductive casing  200  that indirectly charges the atomized fluid. More specifically, as high voltage electric current flows through the conductive casing  200 , the high voltage current creates a magnetic field that indirectly charges/ionizes the atomized fluid passing through the aperture  210 . Furthermore, and as illustrated, the non-conductive casing  74  may include a conductive member  76  that couples to the power supply  72 . The conductive member  76  enables high voltage current from the power supply  72  to form a magnetic field within the non-conductive casing  74  that indirectly charges or ionizes the atomized fluid passing through the fluid passage  82 . The indirect charging device  16  may combine the conductive casing  200  with the conductive members  76  in different ways to indirectly charge the atomized fluid. For example, the power supply  72  may supply different amounts of current and voltage to the conductive casing  200  and the conductive member  76  (e.g., progressively increase, progressively decrease, or alternate current flow and voltage between the conductive members). The indirect charging device  16  may also enable a user to turn off the current flow to the conductive casing  200  or the conductive member  76  depending on the application. 
     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.