Abstract:
An electrostatic spray system, comprising a hand held device having an inlet and an outlet. The hand held device includes a charging device for producing a high voltage charging field and a spray nozzle having an outlet, the outlet being disposed within the charging field. The system further includes an air movement system disposed within the hand held device, the air movement system configured to produce an airflow around the spray nozzle and through the high voltage charging field to create a directionally controllable electrostatic charged mist existing the hand held device at low velocities.

Description:
CLAIM OF PRIORITY 
     This application claims the benefit of U.S. Provisional Application No. 61/244,308, filed Sep. 21, 2009, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     Electrostatic sprayers are used to provide an electrical potential difference between charged fluid particles and a target device. However, existing systems require numerous components, contain complicated designs, and further, the velocity of the charged particles exiting these electrostatic sprayers is increased, thereby reducing the efficiency of such devices. This results in an overspray and/or charged particles passing the intended target ultimately requiring more fluid to spray the intended target. 
     SUMMARY 
     Embodiments provided herein comprise an electrostatic spray system having a hand held device in which an airflow system generates an airflow from within the hand held device. In particular, a fan disposed within the hand held device directs a forced air flow over a nozzle and charging device to create a directionally controllable electrostatic charged mist exiting the hand held device at relatively low velocities. Power for generating an electrostatic field, operating the fan, and facilitating fluid flow for the electrostatic spray system is provided by a remote source, which contains a spray mixture tank, a liquid pump, and an electrical source to support the functions of the hand held device. The hand held device and remote source are detachably connected together via a hose and electric wires. 
     In operation, air generated within the hand held device is forced over and/or otherwise around the nozzle (but not through the nozzle tip) so that the mist exiting the nozzle is mixed with the forced airflow and electrically charged via the high voltage charging device. The forced airflow over the nozzle and use of the high voltage charging device generate the directable charged mist cloud for depositing the spray mixture onto a target thereby resulting in electrostatic deposition on the chosen target. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of an electrostatic spray system in which a low velocity directionally controllable electrostatic charged mist is output therefrom; 
         FIG. 2  is a top view of a portion of the electrostatic spray system of  FIG. 1 ; 
         FIG. 3  is an illustration of a charging device disposed adjacent a nozzle outlet of the electrostatic spray system of  FIGS. 1 and 2 ; and 
         FIG. 4  is an illustration of an alternate configuration of the charging device. 
     
    
    
     DETAILED DESCRIPTION 
     In the description which follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawings are not necessarily to scale and certain features may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness. 
       FIG. 1  is an illustration of an electrostatic spray system  10  in which an internal air movement system  12  is employed to advantage to output a low velocity and directionally controllable electrostatic charged mist M. Electrostatic spray system  10  comprises a hand held device  14  detachably coupled to a remote base or cart  16  via a retractable hose  18 . Cart  16  comprises a pump  20 , a fluid supply tank  22 , a power source  24  and necessary control elements (i.e., microcontroller, relays, etc.) for operation of system  10 , and in particular, operation of hand held device  14 . 
     Referring to  FIGS. 1 and 2 , hand held device  14  generally comprises a tubular member or chamber  26  having an air inlet  28  and an air outlet  30 . Chamber  26  is sized to house and/or otherwise support a spray nozzle  32 , a high voltage power supply or charging element  34  ( FIG. 1 ) electrically coupled to a remote power source  24 , a charging device  36  disposed generally adjacent to outlet  30  and nozzle  32  for creating a high voltage charging field, and air movement system  12 . In operation, air movement system  12  draws air within inlet  28  and forces airflow along the airflow path designated by arrows  38  over and/or otherwise around nozzle  32  and charging device  36 , the forced airflow and charging device  36  facilitating the delivery of electrostatic charged mist M through outlet  30  at relatively low velocities. 
     Referring specifically to  FIG. 2 , air movement device  12  comprises an axial fan  40  to generate airflow through chamber  26  and over nozzle  32 . Preferably, axial fan  40  is sized to provide an airflow rate between 3,000 cubic feet per minute to 5,200 cubic feet per minute; however, it should be understood that fan  40  may be otherwise sized to provide a higher or lower airflow rate. Furthermore, it should be understood that air movement device  12  may be otherwise configured, such as, for example, by utilizing a remotely positioned fan coupled to inlet  28  via a hose (not illustrated) or other types of air movement generating devices. In addition, while  FIG. 2  illustrates a single air movement device  12 , it should be understood that additional air movement devices  12  can be utilized to provide the desired airflow through chamber  26 . 
     In the embodiment illustrated in  FIG. 2 , nozzle  32  comprises a fluid inlet  50  coupleable to fluid supply tank  22  via hose  18  ( FIG. 1 ) and a fluid outlet  52  for discharging fluid therefrom. According to some embodiments, nozzle  32  comprises an outlet  52  formed of a ceramic tip  70 , such as, for example, the TX3 model manufactured by Spray Systems; however, it should be understood that nozzle outlet  52  may be otherwise formed. For example, nozzle outlet  52  can be constructed using a tip  70  of any type of non-conductive material such as, but not limited to, plastic. 
       FIG. 3  is an illustration of charging device  36  disposed adjacent nozzle  32  of the electrostatic spray system  10  of  FIGS. 1 and 2 . In the embodiment illustrated in  FIG. 3 , charging device  36  comprises a generally circular charging ring  36   a  disposed around nozzle  32 . According to some embodiments disclosed herein, charging ring  36   a  is coupled to a charging device support member  54  such that nozzle outlet  52  is concentrically disposed within charging ring  36   a . According to some embodiments, charging ring  36   a  comprises a diameter of approximately 1.25 inches and a length “L” of approximately 1 inch and is formed of 316 stainless steel. Furthermore, as illustrated in  FIG. 3 , charging ring  36   a  encircles and/or is otherwise disposed around nozzle outlet  52 ; however, it should be understood that charging ring  36   a  may only partially encircle nozzle outlet  52 . In addition, it should be understood that charging ring  36   a  may be otherwise sized (i.e., a larger or smaller diameter and/or length L) and be formed of any type of conductive material. It should be understood that charging ring  36   a  may be otherwise mounted. For example, charging ring  36  may be embedded in or otherwise attached to a sidewall of chamber  26  of handheld device  14 . 
     In the embodiment illustrated in  FIG. 3 , charging ring  36   a  is mounted on nozzle  32  such that end  56  of charging ring  36   a  is located approximately 0.25 inches behind or offset from nozzle outlet  52  and end  58  of charging ring  36   a  extends in the opposite direction or forward of the nozzle outlet  52 ; accordingly, as fluid particles flow through nozzle outlet  52 , the fluid particles flow through a high voltage charging field created by charging device  36  to form a directionally controllable electrostatic charged mist, as described in more detail below. 
       FIG. 4  is an illustration of an alternate configuration of charging device  36  of  FIG. 3 . In the embodiment illustrated in  FIG. 4 , charging device  36  comprises a metallic plate  36   b  disposed on the sidewall of chamber  26  generally adjacent to and/or otherwise aligned with nozzle outlet  52  to form a high voltage charging field. As plate  36   b  is charged, fluid particles flowing through nozzle outlet  52  are electrically charged to form the directionally controllable electrostatic charged mist. It should be understood that a greater number of charging plates  36   b  can be used. For example, parallel charging plates  36   b  can be mounted within handheld device  14  on opposite sides of nozzle outlet  52 . In the embodiment illustrated in  FIG. 4 , outlet  30  of chamber  36  is generally oval or racetrack shaped and is configured to produce a generally flat and diverging output of electrostatically charged mist. 
     Charging device  36  is electrically coupled to high voltage power supply/charging element  34  ( FIG. 1 ) to form the electrically charged mist as it exits outlet  30 . In the embodiment illustrated herein, high voltage power supply  34  is mounted on hand held device  14  and converts a DC voltage input (e.g., 12V, 16V, 36V, etc.) to a voltage output level preferably between 3800 and 5200 volts DC to facilitate the of the creation of a high voltage charging field and ultimately, the electrostatic charged mist M; however, it should be understood that power supply  34  may be otherwise located, such as, for example, on cart  16  and convert the DC voltage input to any other desired output level. 
     In operation, nozzle tip  70  in combination with charging device  36  and air movement system  14  produce desired fluid output patterns at predetermined flow rates. For example, according to some embodiments, tip  70  along with charging device  36  and air movement system  14  facilitate the output of a hollow cone discharge area at an angle θ of approximately 80 degrees, as illustrated specifically in  FIG. 1 . In some embodiments, the hollow cone end may extend three to four feet in diameter at a position 4-5 inches from the end of hand held device  14 . Preferably, electrostatic spray system  10 , and in particular, output nozzle  52 , is operated under a pressure of approximately 70 pounds per square inch to provide the large and low velocity spraying area at outlet  30  of hand held device  14 . 
     System  10  is operable when a user presses a switch or button  72  on hand held device  14 . For example, as switch  72  is pressed, pump  20  and air movement system  12  begin to operate. Fluid is pumped from tank  22  via hose  18  to hand held device  14 , and in particular, nozzle  32 . As fluid is pumped to nozzle  32 , air movement system  12  forces the flow of ambient air through chamber  26  (via air inlet  28 ), over nozzle outlet  52  and through charging device  36  (and thus a high voltage charging field). Accordingly, as hand held device  14  is pointed at its intended target, a controlled cloud or mist M of charged fluid droplets exits hand held device  14  directly onto the target. The predetermined airflow generated by internal air movement system  12  over nozzle  32  and charging device  36  creates a low velocity electrostatically charged mist exiting hand held device  14  for depositing on a desired target with minimal overspray or maximal coverage thereon. 
     Although embodiments of the electrostatic spray system  10  have been described in detail, those skilled in the art will also recognize that various substitutions and modifications may be made without departing from the scope and spirit of the appended claims.