Abstract:
A venting member includes a fastener and a gas-permeable member positioned at least partially within the fastener to allow movement of a gas through the fastener, but prevent movement of liquids.

Description:
[0001]     The invention was conceived or reduced to practice in the performance of work under U.S. Government contract #N00019-93-C-0196 award by the U.S. Navy. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates generally to venting members, and more particularly to venting members configured to vent enclosures.  
       BACKGROUND OF THE INVENTION  
       [0003]     Enclosures are used in a wide range of applications and generally provide a protective environment for an electrical component housed in the enclosure. Such an electrical component is housed in the enclosure typically because the component may be damaged when it is exposed to environmental agents, such as water or a lubricant.  
         [0004]     It is sometimes desirable to vent the sealed enclosure to allow pressure equalization between the gases inside the sealed enclosure and the gases in the environment surrounding the sealed enclosure. Venting the enclosure can prevent damage to its internal components, by preventing excessive pressure or vacuum within the enclosure.  
         [0005]     Various methods are currently used to vent an enclosure housing. One such method includes forming a hole or an aperture through the enclosure so that it is not fluid-tight. The aperture allows the passage of gases and liquids between the interior of the enclosure and the enclosure&#39;s surroundings, however, the aperture also allows liquids to enter the enclosure. To protect the electrical components, a drain hole is typically formed in the enclosure to allow liquid accumulated in the enclosure to drain. Also, the electrical component is typically potted or encased with an epoxy material to prevent contact with liquid in the enclosure. However, this method is somewhat undesirable because of the costs associated with potting electrical components and because the epoxy tends to retain heat given off by the electrical components, and in many instances the electrical components cannot be potted because the potting material degrades performance or prevents operation.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention attempts to address the shortcomings of current methods of venting an enclosure by providing a venting member including a fastener and a gas-permeable member positioned at least partially within the fastener to allow movement of a gas through the fastener.  
         [0007]     The present invention also provides a vented assembly including a venting member including a fastener and a gas-permeable member positioned at least partially within the fastener to allow movement of a gas through the fastener. The vented assembly also includes at least one wall defining in part an enclosure. The fastener couples to the at least one wall to fluidly connect a space inside the enclosure and a space outside the enclosure.  
         [0008]     Further, the present invention provides a venting member including a fastener including a body portion and a head portion. The body portion defines a longitudinal axis. The venting member also includes an aperture formed through the body portion and the head portion, and a gas-permeable member positioned at least partially within the aperture to allow gas to pass through the fastener via the aperture. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     In the drawings, wherein like reference numerals indicate like parts:  
         [0010]      FIG. 1  is a perspective cutaway view of a venting member of the present invention;  
         [0011]      FIG. 2  is a cross-sectional view of the venting member of  FIG. 1  coupled to a wall of an enclosure, illustrating a first configuration of the venting member; and  
         [0012]      FIG. 3  is a cross-sectional view of the venting member of  FIG. 1  coupled to the wall of the enclosure, illustrating a second configuration of the venting member.  
         [0013]     Before at least one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limited. 
     
    
     DETAILED DESCRIPTION  
       [0014]     A venting member  10  in the form of a fastener  14  is shown in  FIG. 1 . The venting member  10  is configured to be coupled to a wall  18  (see  FIGS. 2-3 ) of an enclosure (not shown) to provide a passageway for gases to move between a space inside the enclosure and the environment outside the enclosure. In the illustrated construction, the fastener  14  is in the form of a bolt or a cap screw having a threaded body portion  22  and a head portion  26  configured to be engaged by a tool (not shown). However, in other constructions of the venting member (not shown), the venting member may be in the form of any of a number of different fasteners, such as, but not limited to, a rivet or a nail. Also, depending on the application, the fastener  14  may be made from metal or plastic.  
         [0015]     As shown in  FIG. 1 , an aperture  30  is formed through the fastener  14  along a longitudinal axis  34  defined by the body portion  22  of the fastener  14 . A first reduced-diameter portion  38  of the aperture  30  is located at an end of the aperture  30  near the head portion  26  of the fastener  14 , and a second reduced-diameter portion  42  of the aperture  30  is located at an opposite end of the aperture  30 . A gas-permeable member  46  is supported in the aperture  30  and secured therein between the first and second reduced-diameter portions  38 ,  42 . In the illustrated construction, the gas-permeable member  46  is cylindrical in shape and press-fit within the aperture  30 . Also, in the illustrated construction, the gas-permeable member  46  extends substantially along the entire length of the threaded body  15  of fastener  14 . Alternatively, the gas-permeable member  46  may be a substantially planar membrane extending across the aperture  30 . Further, in yet other constructions of the venting member (not shown), the gas-permeable member  46  may define any of a number of different shapes, and may be configured in any of a number of different lengths along the longitudinal axis  34 .  
         [0016]     The gas-permeable member  46  allows the passage of gases through the aperture  30 , while blocking the passage of liquids through the aperture  30 . The press-fit connection between the gas-permeable member  46  and the aperture  30  ensures that substantially no liquids leak through the aperture  30 . The gas-permeable member  46  may be made from a single piece of polytetrafluoroethylene (PTFE), otherwise known by the trade name TEFLON®. Alternatively, the gas-permeable member  46  may include a core (not shown) made from another gas-permeable polymeric material and a PTFE coating over the core. In yet other constructions of the venting member (not shown), other polymers or a gas-permeable ceramic material may be used to achieve an acceptable permeability rate for a particular application of the venting member.  
         [0017]     As shown in  FIG. 1 , a screen  50  is also supported in the aperture  30  between the gas-permeable member  46  and the first reduced-diameter portion  38 . The screen  50  is configured to protect the gas-permeable member  46  from being damaged by contact with particles, tools, or the like. In the illustrated construction, the screen  50  is made from metal and is compressed between the gas-permeable member  46  and the first reduced-diameter portion  38  of the aperture  30 .  
         [0018]     The venting member  10  may be manufactured in any of a number of different ways. However, in the illustrated construction, the aperture  30  and first reduced-diameter portion  38  are initially formed in the fastener  14 . The screen  50  is then inserted adjacent the first-reduced diameter portion  38 , and the gas-permeable member  46  is press-fit into the aperture  30  to compress the screen  50  against the first reduced-diameter portion  38 . Further, the second reduced-diameter portion  42  is formed by a crimping process to secure the gas-permeable member  46  and the screen  50  in the aperture  30 .  
         [0019]      FIGS. 2-3  illustrate respective vented assemblies  54 ,  56  with each vented assembly  54 ,  56  including the venting member  10  being coupled to the wall  18  of the enclosure. The threaded body portion  22  of the fastener  14  threadably engages a threaded aperture  58  through the wall  18 . As shown in  FIG. 2 , a first configuration of the venting member  10  includes a seal  62  in the form of an O-ring  66  being preloaded against the wall  18  by the head portion  26  of the fastener  14 . The O-ring  66  provides a seal such that leakage of gases and/or liquids through the threaded aperture  58  in the wall  18  is substantially prevented by the O-ring  66 . In other constructions of the vented assembly (not shown), the seal  62  may take any of a number of different forms, including, but not limited to, a rubber washer and a paper-based gasket.  
         [0020]      FIG. 3  shows a second configuration of the venting member  10  including a thread-locking device  70  coupled to the threaded body portion  22  of the fastener  14  and the threaded aperture  58  in the wall  18 . In the illustrated construction, the thread-locking device  70  is in the form of a conventional thread-locking adhesive  74  applied between the threaded body portion  22  of the fastener  14  and the threaded aperture  58  in the wall  18 . The thread-locking adhesive  74  provides a seal such that leakage of gases and/or liquids through the threaded aperture  58  in the wall  18  is substantially prevented.  
         [0021]     The enclosure may house components (not shown) for use in any of a number of different applications. The venting member  10  of the present invention is especially useful for venting a enclosure housing electrical components. Such electrical components could be damaged if they were to come into contact with liquids. Since the venting member  10  allows the movement of gases between the interior and exterior of the enclosure while blocking the corresponding movement of liquids, the electrical components are protected from the liquid, and do not require additional protective structure (e.g., a potting compound). Some of the different applications whereby the venting member  10  may be used may include, but are not limited to, field electronics enclosures, outdoor lighting enclosures, avionics enclosures subject to altitude-related pressure changes, and marine applications subject to intermittent water exposure.