Abstract:
A waterproof and breathable plug includes a plug body having a mounting base, an air vent on the mounting base, a tubular screw rod at one side of the mounting base and arched blocks at the other side of the mounting base, a waterproof and breathable membrane covering the air vent, and a cover member having a cap nut threaded onto the arched blocks and air valves mounted in the cap nut and movable with rotation of the cap nut to adjust the open rate of the opening between each two adjacent arched blocks of the plug body and to further regulating the breathing rate.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to plugs for use in a waterproof box or electrical box and more particularly, to a waterproof and breathable plug, which prohibits permeation of outside water and allows ventilation of the waterproof box or electrical box to expel moisture. 
         [0003]    2. Description of the Related Art 
         [0004]    A waterproof box or electrical box has electric and electronic components mounted therein. The box body may be made of metal. When outside water molecules enter the box body or during exchange between hot air and cold air in the box body, the internal electric and electronic components may get rusted. In order to expel internal moisture, an electrical box generally provides a through hole and a waterproof and breathable plug mounted in the through hole. A conventional waterproof and breathable plug for this purpose is known comprising a plug body defining therein a air passage, a hollow cap nut fastened to plug body, and a waterproof and breathable membrane mounted in the air passage in the plug body to prohibit outside water from entering the inside space of the electrical box and to allow ventilation through the electrical box. 
         [0005]    According to the aforesaid prior art waterproof and breathable plug design, the breathing rate is fixed and not changeable to fit different electrical boxes or different application requirements. Because the waterproof power of the used waterproof and breathable membrane is fixed, it cannot prohibit water from entering the inside space of the electrical box during a bad weather condition, such as stormy weather or hurricane. Therefore, the waterproof function of the aforesaid prior art design must be enhanced. 
         [0006]    Further, it is difficult to insert the thin waterproof and breathable membrane into the inside of the air passage and then to fixedly secure the thin waterproof and breathable membrane in place. During installation, the thin waterproof and breathable membrane may be damaged easily. Further, an adhesive may be used to fasten the thin waterproof and breathable membrane to the inside of the plug body. After a long use, the adhesive may be aged and fall out of place to clog the air passage. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a waterproof and breathable plug, which is practical for use in an electrical box to prohibit permeation of outside water, allowing breathing of the electrical box. It is another object of the present invention to provide a waterproof and breathable plug, which is adjustable to regulate the breathing rate, fitting different electrical boxes or different weather conditions. It is still another object of the present invention to provide a waterproof and breathable plug, which facilitates installation without damaging the waterproof and breathable membrane. It is still another object of the present invention to provide a waterproof and breathable plug, which allows installation of added waterproof and breathable membranes to enhance waterproof effects. 
         [0008]    To achieve these and other objects of the present invention, a waterproof and breathable plug comprises a plug body, at least one waterproof and breathable membrane and a cover member. The plug body comprises a mounting base having opposing front and back sides, an air vent cut through the front and back sides of the mounting base, a tubular screw rod perpendicularly extending from the back side of the mounting base in communication with the air vent, a plurality of arched blocks perpendicularly extended from the front side of the mounting base and equiangularly spaced around the air vent and a plurality of openings respectively defined between each two adjacent arched blocks, each arched block having an outer wall and outer threads located on the outer wall. The at least one waterproof and breathable membrane is attached to the front side of the mounting base of the plug body over the air vent and surrounded by the arched blocks. The cover member is fastened to the arched blocks of the plug body and movable relative to the arched blocks of the plug body to close/open the openings, comprising a plurality of air valves and a cap nut. The cap nut has a threaded inside wall threaded onto the outer threads of the arched blocks of the plug body and a recessed chamber defined therein and surrounded by the threaded inside wall. The air valves are perpendicularly mounted inside the recessed chamber in an equiangularly spaced manner and movable with the cap nut relative to the arched blocks of the plug body to adjust the open rate of the openings. 
         [0009]    When compared to a same size of prior art waterproof and breathable plug, the invention has the advantage of allowing adjustment of the open rate of the openings. When used in an electrical box, the invention enhances air exchange between the inside space of the electrical box and the atmosphere. Therefore, the invention is practical for use in a big scale electrical box to enhance ventilation and to expel moisture produced due to cross-effects between internal hot air and external cold air. When in a stormy or heavy raining condition, the open rate of the openings can be minimized to stop external water molecules or fluid from entering the electrical box. 
         [0010]    Further, at least one cushion ring may be used and fitted into the space surrounded by the arched blocks to hold down the at least one waterproof and breathable membrane. 
         [0011]    Further, the cushion ring is elastic. When the aforesaid cushion ring is inserted into the cylindrical space surrounded by the arched blocks, a friction force is produced between the arched blocks and the cushion ring, securing the cushion ring firmly in place. Further, multiple waterproof and breathable membranes (cloths) may be used and attached to the mounting base of the plug body over the air vent and held down by the cushion ring(s), enhancing waterproof effects. 
         [0012]    Further, it is to be understood that the waterproof and breathable plug can be used in any of a variety of electrical boxes, including waterproof boxes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is an exploded view in section of a waterproof and breathable plug in accordance with the present invention. 
           [0014]      FIG. 2  is a sectional assembly view, in an enlarged scale, of the waterproof and breathable plug shown in  FIG. 1 . 
           [0015]      FIG. 3  is an exploded view in section of an alternate form of the waterproof and breathable plug in accordance with the present invention. 
           [0016]      FIG. 4  is a sectional assembly view, in an enlarged scale of the waterproof and breathable plug shown in  FIG. 3 . 
           [0017]      FIG. 5  is similar to  FIG. 4  but showing multiple waterproof and breathable membranes installed. 
           [0018]      FIG. 6  is a schematic applied view of the present invention, showing the waterproof and breathable plug used in an electrical box. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0019]    Referring to  FIGS. 1 and 2 , a waterproof and breathable plug in accordance with the present invention is shown comprising a plug body  2 , a waterproof and breathable membrane (cloth)  3  and a cover member  5 . 
         [0020]    The plug body  2  comprises a mounting base  21 , an air vent  211  located on the mounting base  21  at the center, a tubular screw rod  23  perpendicularly extending from one side of the mounting base  21  in communication with the air vent  211 , a plurality of arched blocks  25  perpendicularly extended from the other side of the mounting base  21  and equiangularly spaced around the air vent  211  and a plurality of openings  255  respectively defined between each two adjacent arched blocks  25 . Each arched block  25  has an outer wall  251  and outer threads  253  located on the outer wall  251 . 
         [0021]    The waterproof and breathable membrane (cloth)  3  is attached to one side of the mounting base  21  of the plug body  2  over the air vent  211  and surrounded by the arched blocks  25 . 
         [0022]    The cover member  5  comprises a plurality of air valves  51  and a cap nut  53 . According to this embodiment, the number of the arched blocks  25  and the number of the air valves  51  are 4. The cap nut  53  has a threaded inside wall  57  and a recessed chamber  55  defined therein and surrounded by the threaded inside wall  57 . The air valves  51  are perpendicularly mounted inside the recessed chamber  55  in an equiangularly spaced manner such that an annular space  59  is defined in the cap nut  53  around the air valves  51  and surrounded by the threaded inside wall  57  for receiving the arched blocks  25  of the plug body  2 . 
         [0023]    The outer threads  253  of the arched blocks  25  are threaded into the threaded inside wall  57  to have the arched blocks  25  be received in the annular space  59  between the cap nut  53  and the air valves  51  so that the openings  255  are partially covered by the cover member  5  and partially left for air exchange. At this time, the air valves  51  are surrounded by the arched blocks  25  and stopped against the waterproof and breathable membrane (cloth)  3 . Thus, the open rate of the openings  255  is adjustable by means of rotating the cover member  5  to move the air valves  51  relative to the arched blocks  25 . 
         [0024]    When compared to a same size of prior art waterproof and breathable plug, the invention has the advantage of allowing adjustment of the open rate of the openings  55 . When used in an electrical box, the invention enhances air exchange between the inside space of the electrical box and the atmosphere. Therefore, the invention is practical for use in a big scale electrical box to enhance ventilation and to expel moisture produced due to cross-effects between internal hot air and external cold air. When in a stormy or heavy raining condition, the open rate of the openings  255  can be minimized to stop external water molecules or fluid from entering the electrical box. 
         [0025]    Further, an adhesive may be used to fasten the border area of the waterproof and breathable membrane (cloth)  3  to the periphery of the air vent  211  of the mounting base  21  of the plug body  2 , enhancing the fixation strength of the waterproof and breathable membrane (cloth)  3 . 
         [0026]    Alternatively, the border area of the waterproof and breathable membrane (cloth)  3  can be fixedly secured to the periphery of the air vent  211  of the mounting base  21  of the plug body  2  by means of a high-frequency sealing apparatus, enhancing the fixation strength of the waterproof and breathable membrane (cloth)  3 . 
         [0027]    Further, the air valves  51  of the cover member  5  are smoothly arched, fitting the curvature of the arched blocks  25  of the plug body  2  and assuring smooth adjustment of the open rate of the openings  255 . 
         [0028]      FIGS. 3 and 4  illustrate an alternate form of the waterproof and breathable plug. This second embodiment is substantially similar to the aforesaid first embodiment with the exception of an added cushion ring  4  that is fitted into the cylindrical space  250  surrounded by the arched blocks  25  to hold down the waterproof and breathable membrane (cloth)  3 . The waterproof and breathable membrane (cloth)  3  and the cushion ring  4  can be inserted into the cylindrical space  250  surrounded by the arched blocks  25  by fingers, and then the cover member  5  is fastened to the arched blocks  25  of the plug body  2  to finish the installation. Thus, mounting and dismounting of the waterproof and breathable membrane (cloth)  3  and the cushion ring  4  can be done conveniently by hand without using any tools. 
         [0029]    According to this second embodiment, the air valves  51  of the cover member  5  are stopped at the cushion ring  4  against the waterproof and breathable membrane (cloth)  3 . Subject to the thickness of the cushion ring  4 , the cover member  5  is lifted relative to the plug body  2  to increase the breathing rate of the openings  255  of the plug body  2  in the axial direction. When more cushion rings  4  are installed, the elevation of the cover member  5  relative to the arched blocks  25  of the plug body  5  is relatively increased to relatively increase the breathing rate of the openings  255  of the plug body  2  in the axial direction. Further, each installed cushion ring  4  also provides a waterproof function. 
         [0030]    Referring to  FIG. 5 , the aforesaid cushion ring  4  is elastic and press-fitted into the cylindrical space  250  surrounded by the arched blocks  25  to hold down the waterproof and breathable membrane (cloth)  3  in the air vent  211 . When the aforesaid cushion ring  4  is inserted into the cylindrical space  250  surrounded by the arched blocks  25 , a friction force is produced between the arched blocks  25  and the cushion ring  4 , securing the cushion ring  4  firmly in place. Further, multiple waterproof and breathable membranes (cloths)  3  may be used and attached to the mounting base  21  of the plug body  2  over the air vent  211  and held down by the cushion ring(s)  4 , enhancing waterproof effects. 
         [0031]    Referring to  FIG. 6  and  FIG. 3 , during application, an O-ring  7  is sleeved onto the tubular screw rod  23  of the plug body  2  and attached to one side the mounting base  21 , and then the tubular screw rod  23  of the plug body  2  is inserted into a mounting through hole  81  on the electrical box, referenced by  8 , and then a locknut  8  is threaded onto the tubular screw rod  23  of the plug body  2  and stopped against the inside wall of the electrical box  8  to lock the waterproof and breathable plug to the electrical box  8 . 
         [0032]    Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.