Patent Publication Number: US-2011067765-A1

Title: Self sealing drain fitting

Description:
FEDERAL RESEARCH STATEMENT 
     The U.S. Government may have certain rights in this invention pursuant to contract number N00019-06-C-0081 awarded by the Naval Air Systems Command (NAVAIR). 
    
    
     BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein generally relates to environmental control systems. More particularly, the subject matter disclosed herein relates to drainage of excess fluid from environmental control systems. 
     When an environmental control system (ECS) shuts down, water pools at various locations in the ECS, for example, in the headers and the core of the condenser. When the ECS is then restarted, the excess water can be ejected from the system through, for example, cooling vents, onto components of, for example, a helicopter cockpit. To reduce the amount of excess water in the ECS, open weep holes are installed at low points of the ECS to allow the water to drain as it accumulates. Because the weep holes are always open, however, there is air leakage from the ECS through the weep holes during operation which causes a significant performance drop when compared to an ECS without weep holes. The part would well receive a drainage solution which reduces the amount of excess moisture while reducing the performance impact of the weep hole configuration. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the invention, a drain assembly includes a buoyant spherical ball and a drain fitting including at least one drain channel. The drain fitting is securable at a drain location wherein pressurization at the drain location seals the buoyant spherical ball against the drain channel. 
     According to another aspect of the invention, an environmental control system includes a collection area of fluid in the environmental control system and a drain assembly located at the collection area. The drain assembly includes a buoyant spherical ball and a drain fitting including at least one drain channel. The drain fitting is securable at a drain location wherein pressurization of the environmental control system at the drain location seals the buoyant spherical ball against the drain channel. 
     According to yet another aspect of the invention, a method of operating a drain assembly for an environmental control system includes locating the drain assembly at a fluid collection area of the environmental control system. The drain assembly includes a buoyant spherical ball and a drain fitting including at least one drain channel. The drain fitting is securable at a drain location. An interior of the environmental control system is pressurized and the buoyant spherical ball is sealed to the drain fitting via the pressurization of the interior of the environmental control system. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a cross-sectional view of an embodiment of a self-sealing drain fitting; 
         FIG. 2  is a perspective view of an embodiment of a drain fitting installed at an environmental control system; 
         FIG. 3  is another cross-sectional view of the self-sealing drain fitting of  FIG. 1 ; and 
         FIG. 4  is a cross-sectional view of another embodiment of a self-sealing drain fitting. 
     
    
    
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Shown in  FIG. 1  is a drain fitting  10  for, for example, an environmental control system (ECS). The drain fitting  10  is located at, for example, a condenser header  12 . As shown in  FIG. 2 , however, the drain fitting  10  may be located at any point on the ECS  14  where excess water accumulates, typically a gravitational low point. 
     Referring again to  FIG. 1 , the header  12  includes a boss  16  extending from a header hole  18  to receive the drain fitting  10 . The drain fitting  10  is secured in the boss  16  by, for example a threaded connection  20  and extends through the header hole  18  into an interior  22  of the ECS  14 . An o-ring  24  may be disposed between the threaded connection  20  and a head  26  of the drain fitting  10  to provide sealing between the drain fitting  10  and the boss  16 . The drain fitting  10  includes at least one drain opening  28  therethrough, disposed along a fitting axis  30 . 
     A spherical ball  32 , having a ball diameter  34  greater than an opening diameter  36  of the drain opening  28  is located in the drain fitting  10  upstream of the drain opening  28 . The spherical ball  32  is configured to be buoyant, and in some embodiments is formed from a plastic material, such as Vespel®. The spherical ball  32  is of a size and shape to seat to the drain opening  28  when the ECS  14  is operated due to operating pressure of the ECS  14 . The pressure forces the spherical ball  32  into a chamfer  38  in the drain opening  28  with a profile which, in some embodiments, matches the profile of the spherical ball  32 . The matching profiles result in a seal between the spherical ball  32  and the chamfer  38  which reduces leakage from the ECS  14  during operation. Referring now to  FIG. 3 , when operation of the ECS  14  is stopped, liquid  40  pools in the area of the drain fitting  10 . Because the operation pressure is no longer holding the spherical ball  32  in contact with the chamfer  38 , and because of characteristics of the spherical ball  32 , the spherical ball  32  begins to float in the liquid  40  and moves away from the chamfer  38 . The liquid  40  then is able to proceed down the drain opening  28  and away from the ECS  14  since the drain opening  28  is free of obstruction. 
     In some embodiments, the drain fitting  10  includes a retention cage  42 . The retention cage  42  extends into the interior  22  around the spherical ball  32  to prevent escape of the spherical ball  32  into the interior  22  of the ECS  14 . The retention cage  42  is configured with a plurality of cage openings  44  which effectively prevent escape of the spherical ball  32 , but allow liquid  40  from the interior  22  to enter the drain fitting  10 . In other embodiments, as shown in  FIG. 4 , the spherical ball  32  is located in the boss  16  and retained in a boss interior  46  by the drain fitting  10 . The boss interior  46  includes a boss opening  48 , of smaller diameter than the spherical ball  32  to prevent escape of the spherical ball  32  into the interior  22  of the ECS  14 . Further, the boss  16  may include an interior chamfer  50 , of the same shape as the spherical ball  32 . 
     Liquid  40  drained from the drain fitting  10  may, as shown in  FIG. 3 , drain freely into the environment outside of the ECS  14 . Alternatively, as shown in  FIG. 4 , the liquid  40  may drain from the drain fitting  10  to a holding tank  52  or the like for removal from the system at a later time. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.