Abstract:
A waterproof structure of a respiratory tube is provided. The waterproof structure comprises a hollow body and a lid. The hollow body has a first opening end and a second opening end opposing to the first opening end. The lid pivots onto the hollow body at the first opening end. Before the lid is immersed into liquid, the gravity of the lid can keep the lid at a certain position so that the respiratory tube is well-ventilated. After a part of the lid is immersed into the liquid, the buoyancy provided by the liquid forces the closing surface thereof to substantially seal the first opening end and prevent liquid from going into the tube.

Description:
RELATED APPLICATIONS 
     This application claims priority to Taiwan Application Serial No. 096213122, filed on 9 Aug. 2007 and Taiwan Application Serial No. 096216223, filed on 28 Sep. 2007, the disclosures of which are incorporated herein by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a waterproof structure of a respiratory tube, and more particularly, relates to a waterproof structure of a respiratory tube used for snorkeling. 
     2. Descriptions of the Related Art 
     Respiratory tubes are essential for snorkeling. Even a beginner who cannot swim can snorkel if he or she knows how to use the respiratory tube. For this reason, manufacturers have continuously improved respiratory tubes to make them more convenient and easier to use. 
     The most important component of the respiratory tube is its waterproof structure. In a conventional waterproof structure, which is disposed at the end of the respiratory tube, there is a floating ball therein that functions much like an air floating bucket. When the respiratory tube is immersed into water, the floating ball will float upwards and seal the respiratory tube with the aid of a properly designed connecting rod that is connected with the floating ball. Sea water then is prevented from entering, allowing the diver to dive into the sea. 
     In addition, a conventional respiratory tube having a waterproof valve is disclosed in U.S. Pat. Nos. 7,077,127 and 6,904,910. The waterproof valve of the respiratory tube comprises a soft diaphragm disposed at a top opening of the respiratory tube by a linkage. When a floating device of the respiratory tube is immersed into water, it will drive the linkage to indirectly move the diaphragm against the opening of the respiratory tube thereby preventing water entry. On the contrary, when the floating device of the respiratory tube departs from water, it will drive the linkage to indirectly move the diaphragm apart the opening. 
     Unfortunately, this conventional waterproof structure requires a complex assembly process and increases the manufacturing cost because of the relatively large number of components. Furthermore, when using the conventional respiratory tube, sometimes the waterproof structure closes prematurely even before the diver dives into the water, or is prone to water entry, thus preventing the respiratory tube from functioning properly. 
     Therefore, it is important to design a simplified waterproof structure that can function properly at all times without it being too costly. 
     SUMMARY OF THE INVENTION 
     One objective of this invention is to provide a waterproof structure of a respiratory tube, which can seal or open the respiratory tube depending on the buoyancy provided by the liquid and the gravity of the waterproof structure itself. 
     Another objective of this invention is to provide a waterproof structure of the respiratory tube, which can either be formed integrally or by joining individual components together, thus eliminating a complex assembly process as used in the prior art and reducing the manufacturing costs thereof. 
     Yet a further objective of this invention is to provide a waterproof structure of a respiratory tube, which is designed in such a manner that its own lid will automatically shut without any external driving force, thus improving the waterproof efficacy of the respiratory tube. 
     To this end, a waterproof structure of a respiratory tube disclosed in this invention comprises a hollow body and a lid. The hollow body comprises two opening ends opposite to each other. The lid is pivoted onto the hollow body at the first opening end and is adapted to rotate about the pivot. When the lid is not immersed into the liquid, a fluid communication will be formed between the two opening ends by gravity. On the contrary, when part of the lid is immersed in the liquid, the lid will close the first opening end of the tube due to the buoyancy provided by the liquid to prevent liquid entry. 
     The detailed technology and preferred embodiments implemented for the subject invention are described in the following paragraphs accompanying the appended drawings for the people skilled in this field to well appreciate the features of the claimed invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic perspective view of the components of a conventional waterproof structure; 
         FIG. 1B  is a schematic perspective view of the conventional waterproof structure; 
         FIG. 2A  is a schematic cross-sectional view of the waterproof structure of the present invention when the lid is not immersed in the fluid; 
         FIG. 2B  is a schematic perspective view of the waterproof structure of the present invention when the lid is not immersed in the fluid; 
         FIG. 3A  is a schematic cross-sectional view of the waterproof structure of the present invention when the lid is immersed in the fluid; 
         FIG. 3B  is a schematic perspective view of the waterproof structure of the present invention when the lid is immersed in the fluid; and 
         FIG. 4  is a schematic cross-sectional view of the waterproof structure when the lid is immersed in the fluid in another embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1A and 1B  illustrate a conventional respiratory tube having a waterproof structure which mainly comprises a main body  10  and a cover  20 , with a blocking device  30  disposed inside the cover  20 . The main body  10  is shaped into a hollow tube with a hollow opening  14  which may be extended to the opening of the said respiratory tube. A plurality of fasteners  11 ,  12  and  13  are provided on the main body  10  for connection with the cover  20 . The cover  20  is shaped like a bowl and has the blocking device  30  therein. The blocking device  30  comprises a directional moving rod  31  disposed through the axial hole of the cover  20 , a cap  32  disposed above the directional moving rod  31  and a floating element  33  hooked below the directional moving rod  31 . When the floating element  33  floats upwards due to the buoyancy provided by the liquid, it will drive the directional moving rod  31 , so that the cap  32  will seal the opening  14 . 
       FIG. 2B  is a schematic perspective view of a waterproof structure  40  in accordance with one preferred embodiment of this invention, while  FIG. 2A  is a schematic cross-sectional view of the waterproof structure  40  as shown in  FIG. 2B . The waterproof structure  40  comprises a hollow body  41  and a lid  50 . The waterproof structure is formed integrally or by assembling major components together. A complex assembly process as used in the prior art is thus eliminated, as well as the high manufacturing costs. 
     The hollow body  41  has a first opening end  411  and a second opening end  412  opposite to the first opening end  411 . The first opening end  411  is disposed at the upper end of the hollow body  41  to form a fluid communication between the hollow body  41  and the atmosphere. The second opening end  412  is disposed at the lower end of the hollow body  41  for connection with the respiratory tube. 
     The lid  50  comprises a pivot  51 , a closing surface  52 , an enclosed chamber  53  and a venting aperture  54 . In particular, the pivot  51  of the lid  50  is disposed at the first opening end  411  of the hollow body  41  to allow the lid  50  to rotate about the pivot  51 . In addition, the contour of the closing surface  52  is adapted to match the first opening end  411 , so that it can seal the first opening end  411  of the hollow body  41  to prevent liquid from entering the respiratory tube via the first opening end  411 . In this embodiment, the closing surface  52  is a part of the lid  50 . Alternatively, in another embodiment, the closing surface  52  is adapted to define a sidewall of the enclosed chamber  53 , of which the sidewall faces the first opening end  411 . Those of ordinary skill in the art can change the position of the closing surface  52 , which is not limited herein. 
     Additionally, the overall density of the enclosed chamber  53  is less than that of the liquid, so when the enclosed chamber  53  is immersed into the liquid, the buoyancy provided by the liquid will drive the lid  50  to rotate about the pivot  51  to seal the first opening end  411  of the hollow body  41 . When the lid  50  is not immersed into the liquid, or when only part of the lid  50  is immersed into the liquid with the lid  50  still separated from the first opening end  411  of the hollow body  41 , the atmospheric air outside the first opening end  411  will ventilate within the hollow body  41  via the venting aperture  54  and further flow into the respiratory tube via the second opening end  412 . 
       FIGS. 2A and 3A  illustrate the properties of the waterproof structure  40 . As the lid  50  of the waterproof structure  40  of this invention is pivoted between the first and second positions, a portion thereof can move along the contour of the hollow body  41  to allow the waterproof structure  40  to function smoothly. In particular, as shown in  FIG. 2A , when the lid  50  has not yet been immersed into the liquid, the lid  50  tends to stay at the first position due to its own gravity, so that a fluid connection is formed between the atmosphere and the respiratory tube via the first opening end  411  and second opening end  412 . As a result, the diver can breathe. On the other hand, when the enclosed chamber  53  of the lid  50  is partially immersed in the liquid, the lid  50  is adapted to rotate about the pivot  51  to the second position and stay there due to the buoyancy provided by the liquid to the closed chamber  53 , so that the closing surface  52  seals the first opening end  411  as shown in  FIG. 3A . 
     For example, when the lid  50  of the waterproof structure  40  is immersed in sea water with a density ranging substantially from 1.02 g/cm 3  to 1.07 g/cm 3 , the overall density of the closed chamber  53  of this invention is less than that of the sea water. As a result, the closed chamber  53  will float on the sea water due to the buoyancy, causing the lid  50  to rotate so that the closing surface  52  can seal the first opening end  411 , as shown in  FIG. 3B . In contrast, when the lid  50  of the waterproof structure  40  of this invention leaves sea level, the enclosed chamber  53  will, by gravity, drive the closing surface  52  to depart from the first opening end  411 . The atmospheric air will then flow into the two opening ends  411  and  412  of the hollow body  41  of the waterproof structure  40  via the venting aperture  54 . Consequently, ventilation is formed through the respiratory tube, thereby allowing the divers to breathe. 
     In another preferred embodiment of the invention, the lid  50  of the waterproof structure  40  comprises a floating element  55 , as shown in  FIG. 4 . In this embodiment, the material of the floating element  55  has density lower than the liquid. For example, the material of the floating element  55  has density less than 1.02 g/cm 3  when it is used in the sea water. The material of the floating element  55  can be selected from wood, foam or the combination thereof. Those of ordinary skill in the art can use other materials having lower density, which are not limited herein. Besides, the structure of the floating element  55  is not limited to the closed structure, which depends on the design. In this embodiment, the closing surface  52  is a part of the lid  50 . Alternatively, the closing surface  52  is adapted to define the sidewall of the floating element  55 , of which the sidewall faces the first opening end  411 . 
     When the floating element  55  is partially immersed into the liquid, the buoyancy provided by the liquid will drive the lid  50  to rotate to seal the first opening end  411  thereby preventing liquid entry. When the floating element  55  departs from the liquid, the floating object  50  will, by gravity, drive the closing surface  52  to depart from the first opening end  411 , so that the atmospheric air outside will ventilate within the hollow body  41  of the waterproof structure  40 . 
     In addition, in the preferred embodiment of this invention, a sealing element  521  may be further disposed at the closing surface  52  of the waterproof structure  40 , as shown in  FIG. 2A , so that the closing surface  52  can tightly seal the first opening end  411 . However, this embodiment is only one example, and those of ordinary skill in the art will appreciate that, the sealing element  521 , such as a ring (not shown), may be alternatively disposed at the first opening end  411  to make the closing surface  52  seal the first opening end  411  tightly. 
     The above disclosure is related to the detailed technical contents and inventive features thereof. People skilled in this field may proceed with a variety of modifications and replacements based on the disclosures and suggestions of the invention as described without departing from the characteristics thereof. Nevertheless, although such modifications and replacements are not fully disclosed in the above descriptions, they have substantially been covered in the following claims as appended.