Abstract:
An agitated and pressurized paint pot that is mounted directly to a paint spray dispenser uses a small volume pressurized pot with constant agitation. This design prevents the settling of material and ensures that the materials are applied through the system at a consistent feed rate to meet the specific needs of applying radar absorbing materials.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates in general to spray dispensers for applying liquids and, in particular, to an improved system, method, and apparatus for an agitated and pressurized reservoir that is mounted directly to a paint spray dispenser. 
     2. Description of the Related Art 
     In laboratory research and development, very small quantities of experimental radar absorbing materials (RAM) are carefully applied to test articles in a paint-like form using automated spray dispensing systems. Because of the extremely limited availability and extraordinary cost of some experimental RAMs (i.e., some on the order of $40,000 per gallon), only very small volumes on the order of one pint or less are available for research and development. 
     During the spray application process, RAM require constant agitation to prevent the critical filler components from settling in the suspending liquid in order to provide a highly homogenous application with very consistent physical properties. Non-agitation results in irregular material feed rates and inconsistent applications that compromise system performance. Accurate and repeatable spray application of small quantities of RAM currently presents a significant problem. 
     Although there are several types of spray systems that meet some of the requirements for applying RAM, there is no existing commercial spray system that meets all of the requirements for applying experimental quantities of RAM. Existing spray systems that are compatible with limited volume materials use one of two general classes of automated paint delivery and application systems. The first type is a suction or gravity-fed system with a small volume (e.g., one quart) paint reservoir or “pot” mounted on the dispenser or “gun.” With suction devices the pot is typically located below the gun, while with gravity-fed devices the pot is located above the gun. The second type of system comprises a pressurized, large volume pot (e.g., 5 gallons) that is separated and located upstream from the gun. A hose having a length of about 10 to 50 feet is used to deliver the paint from the pot to the gun. 
     These existing spray systems have several limitations that make their use difficult for experimental RAM application. For example, current suction or gravity-fed RAM application systems do not contain an agitation mechanism, such as the propellers rotated at the bottoms of large volume pots to provide constant stirring during the painting operation. To overcome this limitation, painters are required to regularly stir the paint by hand. This stirring is accomplished by physically shaking the pot and gun system and is difficult to standardize. Painters usually stir the material with an amplitude and frequency that varies significantly with the training, experience and preference of the painter. Lack of a regulated stirring method results in significant variation in the performance of the final system. 
     Moreover, existing suction or gravity-fed systems contain no pressure regulation gauge. These systems use pressurized air flowing across an orifice in the pot to draw the paint out of the pot such that it is propelled by the pressurized air and then released through the nozzle. Since there is no pressure regulation gauge on this system it is impossible to standardize a delivery pressure. Delivery pressure is a critical application parameter in the application of RAM, and variations in application result in performance fluctuations of the final system. With current systems, painters adjust the feed line pressure that again varies based on their experience level. This lack of standardization of pressure settings again results in significant variation in the performance of the final system. 
     The large volume detached pots overcome the primary disadvantages of the suction or gravity fed systems by using pressurized air to force paint out of the pot into the gun and nozzle (which is regulated by a pressure gauge). Large volume systems also have internal agitation mechanisms. However, their use in application of experimental RAM is limited because of the large volumes required to operate them. The smallest existing systems require one to two quarts of paint to hold a minimum pressure charge and because of inefficient shaping of the pot and the use of lengthy hoses between the pots and the spray guns. As a result the actual volume of paint that can be sprayed is significantly less than the original volume. Although these systems can be utilized to standardize spray applications, their large volume requirements make them unfeasible for many developmental activities. Thus, an improved RAM application system would be desirable. 
     SUMMARY OF THE INVENTION 
     Embodiments of a system, method and apparatus for an agitated and pressurized paint pot that is mounted directly to a paint spray dispenser are disclosed. The invention uses a small volume, pressurized pot with constant agitation. This design prevents the settling of material and ensures that the materials are applied through the system at a consistent feed rate to meet the specific needs of highly specialized RAM research and development activities. 
     For example, a small pressure pot that is capable of delivering and dispensing less than one pint of material is provided. Agitation is used within the pot to prevent material settling, positive pressure drives the paint through the system, and a pressure regulator is provided for the accurate regulation of spray pressure. Moreover, since the pot is located immediately adjacent the dispensing nozzle on the spray gun, no hoses requiring excessive paint material volumes are used. 
     In one embodiment, physical rather than magnetic agitation is provided by a small propeller. The agitator may be located below the intake port to provide a more consistent material. In addition, the agitator may be oriented at angle to normal to further enhance the consistency of the material being dispensed. In other advantages of the invention, a larger range of viscosities may be accommodated without requiring a gravity-based system, which would inherently first provide the heaviest particles in the paint. 
     The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the present invention, taken in conjunction with the appended claims and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the features and advantages of the present invention are attained and can be understood in more detail, a more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof that are illustrated in the appended drawings. However, the drawings illustrate only some embodiments of the invention and therefore are not to be considered limiting of its scope as the invention may admit to other equally effective embodiments. 
         FIG. 1  is a schematic, partially-exploded, sectional side view of one embodiment of a painting system constructed in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , embodiments of a system, method and apparatus for dispensing a fluid are disclosed. The invention is well suited for dispensing and spraying paint or other types of fluids capable of being dispensed in such a manner, such as a spray gun and pressure pot application. 
     In one embodiment, the invention comprises a dispenser  11  having cap  13 , a downward extending intake tube  15 , a downward extending agitator  17 , a nozzle  19  (e.g., spray gun), and a pressure regulator and air gauge  21  for regulating a pressure of a spray released by the nozzle. A pressure source  23  (e.g., compressed air) is connected to the pressure regulator and air gauge  21  for pressurizing a fluid in a fluid reservoir  25 . 
     The reservoir  25  is mounted (e.g., threaded) to the cap  13  to form and provide an adequate pressure seal. The reservoir  25  is mounted to the dispenser  11  such that the intake tube  15  and the agitator  17  extend through the cap  13  and into the reservoir  25 . The reservoir  25  has a maximum fluid capacity of about one quart or less to provide a minimum distance for the fluid to travel from the bottom of the reservoir  25  to the nozzle  19 . 
     In one embodiment, the reservoir has an axis  31  (e.g., axis of rotation) about which the reservoir is rotationally symmetric. The intake tube  15  is oriented in a parallel direction with respect to the axis  31 . The intake tube  15  has a distal end  33  that may be angled as shown, and to which is mounted a flexible tube  35  that is oriented at an acute angle with respect to the axis  31 . The reservoir  25  has a sidewall  37  that is parallel to the axis  31 , a bottom  39  that is perpendicular to the axis  31 , and a sloped portion  41  that is tapered from the sidewall  37  to the bottom  39 . A metal band  43  may be added to the outer circumference of the bottom portion of the reservoir  25  to provide a stable platform for the system. 
     As shown in  FIG. 1 , the agitator  17  may be located on a support that is not parallel to the axis  31 . This design improves a consistency of the material being dispensed. The agitator provides constant agitation of the fluid in reservoir  25  to prevent settling of material in the fluid. The agitator  17  may comprise a propeller or an impeller  45  for providing physical agitation of the fluid. The propeller  45  may be rotated up to 800 rpm to avoid over-agitating the fluid and causing cavitation thereof. In one embodiment, a pressure range of up to 15 psi may be maintained in the reservoir  25  during operation. In addition, the propeller  45  may be located over the sloped portion  41  of the reservoir  25  as shown. 
     Although the propeller  45  of the agitator  17  is shown as located vertically above a distal end  47  of the intake tube  15 , propeller  45  may be located below the distal end  47  of the intake tube  15 . In addition, the distal end  47  of the intake tube may align with axis  31  is shown so that the fluid is drawn into the intake tube  15  from the center and bottom  39  of the reservoir  25 . Moreover, the distal end  47  may be located within 0.125 inches from bottom  39  as measured along the axis  31 . 
     In the embodiment shown, the agitator  17  further comprises an agitator motor  51  mounted to the sidewall  37  of the reservoir  25  with a metal strap  53 . A drive cable  55  extends from the agitator motor  51  to an impeller shaft  57 , and the impeller  45  is mounted to a distal end of the impeller shaft  57 . 
     While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.