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FIELD OF TEE INVENTION 
     The present invention relates to an apparatus for preventing reverse flows in a drainage. More specifically, the present invention relates to an apparatus for preventing reverse flows in a drainage, in which a floating device and a reverse flow preventing device act mutually in opposite directions owing to the floating force and the water pressure, and thus the bottom of the body of the apparatus is automatically opened and closed, so that the drainage can efficiently work, and the waste water with foul odors can be prevented from flowing out reversely. 
     BACKGROUND OF THE INVENTION 
     FIGS. 1 and 2 illustrate a conventional drainage reverse flow preventing apparatus  10 . In this apparatus  10 , a filtering device  12  is fixed on the top of a cylindrical tube  11 , and an annular engaging step  13  projects from the lower inner circumference of the cylindrical tube  11 . A protuberance  14  is formed under the annular step  13 . 
     A shaft  15  pass through the protuberance  14 , and a damper  16  is movably secured to the shaft  15 . Further, there is installed a torsion spring  17  between the inner wall of the cylindrical tube  11  and the bottom of the damper  16 . 
     In the conventional drainage reverse flow preventing apparatus  10  constituted as above, when waste water or drainage water does not flow within the cylindrical tube  11 , the damper  16  keeps contacting to the annular step  13 . That is, the damper  16  is kept closed. On the other hand, when waste water or drainage water flows through the cylindrical tube  11 , the damper  16  departs from the annular step  13  so as for the damper  16  to be opened. 
     In this conventional apparatus  10 , however,if the torsion spring  17  loses its elasticity after a long use or due to corrosion, then reverse flows cannot be prevented. Moreover, in this conventional apparatus, the closing of the damper  16  depends only on the force of the torsion spring  17 , and therefore, the sealing between the damper  16  and the annular step  13  is mostly insufficient, with the result that the reverse flow of foul odors cannot be prevented. 
     Besides the above described conventional apparatus, there are various other apparatuses for preventing reverse flows of foul odors and waste water. However, they are not capable of serving as the apparatus for preventing foul odors and waste water simultaneously, but serves only a single function. Further, even this single function cannot be performed perfectly, thereby failing the originally intended purpose. 
     The flow directions of the waste water and the reversely flowing water and foul odors are directly opposite, and therefore, a strong reliability has to be ensured. Such a reliability can be provided through a complicated structure, however, a high cost should be accompanied. Further, such a complicated structure is subjected to a clogging by food stuffs and other foreign materials, with the result that the apparatus loses the intended functions. 
     SUMMARY OF THE INVENTION 
     The present invention is intended to overcome the above described disadvantages of the conventional techniques. 
     Therefore it is an object of the present invention to provide an apparatus for preventing reverse flows in a drainage, in which when draining waste water, a openable/closable plate descends owing to the rise of a floating device by the incoming waste water to open an air-tight sealing part so as to drain waste water efficiently, and when waste water does not flow, the floating device descends owing to the self-gravity, and the openable/closable plate ascends to close the air-tight sealing part so as to prevent the reverse flow of various foul odors. Particularly, in the raining seasons, the reverse flow of the draining water can be prevented, thereby avoiding flooding. 
     In achieving the above object, the apparatus for preventing reverse flows of waste water according to the present invention includes: a round body to be installed in a drain hole; a guide member installed on a second filtering net of the top of the round body, and having a guide at the center of it; an openable/closable device actuating member insertingly installed on the guide member, for moving up and down along the guide owing to a floating force and a self-gravity; and an openable/closable member installed on the guide member, for causing an air-tight sealing part to be opened and closed by being oppositely interlocked to the openable/closable device actuating member. 
     The round body includes: an inner body having the air-tight sealing part at a lower portion thereof; and an outer body having a flange at a lower portion thereof, the inner and outer bodies being detachably coupled together. 
     The guide member includes: a guide having a pair of pinions in the interior thereof, and installed at the center of the second filtering net; and a pair of guide grooves formed in both sides of the guide. 
     The openable/closable device actuating member includes: a floating device having a through-hole at the center of it so as for the floating device to move up and down along the guide; a weight provided in the interior of the floating device; and racks formed on the lower portion of the through hole. 
     The openable/closable member includes: a movable bar having racks at its upper portion, and having a securing part at a lower portion of it; and a reverse flow preventing device having an openable/closable plate and having an elastic member installed thereon, the openable/closable plate and the reverse flow preventing device being detachably coupled together. 
     In another embodiment of the present invention, the apparatus for preventing reverse flows in a drainage according to the present invention includes: a round body to be installed in a drain hole; a guide member installed within the round body, and having a guide at the center of it; an openable/closable device actuating member installed on the top of the guide member, for moving up and down along the guide owing to the floating force and the self-gravity; and an openable/closable member installed under the guide member, for causing a lower portion of the round body to be opened and closed by being oppositely interlocked to the openable/closable device actuating member. 
     The guide member includes: a guide formed at the center of it with pinions installed in the interior of the guide; a securing part having at its bottom a supporting device for supporting the guide; and a water draining part formed within the securing part. 
     The openable/closable device actuating member includes: a floating device having a weight provided in the interior of it, and having a guide accommodating part at the center of the inside of it; and a movable bar having racks formed on the lower portion of it, and having a securing part on the upper portion of it. 
     The openable/closable member includes: a passive body having racks on the inside of it, and having guide grooves on the front and rear faces of it; and a reverse flow preventing device having an openable/closable plate formed at the bottom of it and having a hooking device formed on the upper portion of it, the openable/closable plate and the reverse flow preventing device being detachably coupled together. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above object and other advantages of the present invention will become more apparent by describing in detail the preferred embodiment of the present invention with reference to the attached drawings in which: 
     FIG. 1 is a perspective view of the conventional drainage reverse flow preventing apparatus; 
     FIG. 2 is a sectional view showing the conventional apparatus installed in a draining hole; 
     FIG. 3 is a perspective view of the drainage reverse flow preventing apparatus according to the present invention, showing the state of a normal draining; 
     FIG. 4 is a perspective view of the drainage reverse flow preventing apparatus according to the present invention, showing the state of a reverse flow prevention; 
     FIG. 5 is an exploded perspective view showing the drainage reverse flow preventing apparatus according to the present invention; 
     FIG. 6 is a sectional view of the apparatus of FIG. 5; 
     FIGS. 7 a  to  7   b  are sectional views showing the reverse flow preventing action in the apparatus of the present invention; 
     FIG. 8 is an exploded perspective view showing another embodiment of the drainage reverse flow preventing apparatus according to the present invention; 
     FIG. 9 is a sectional view showing the assembled state of the drainage reverse flow preventing apparatus of FIG. 8; and 
     FIGS. 10 a  and  10   b  are sectional views showing the reverse flow preventing action in the apparatus according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 5 is an exploded perspective view showing the drainage reverse flow preventing apparatus according to the present invention. FIG. 6 is a sectional view of the apparatus of FIG.  5 . FIGS. 7 a  to  7   b  are sectional views showing the reverse flow preventing action in the apparatus of the present invention. 
     A barrel shaped round body  20  which is to be installed in a draining bole  60  includes an inner body  26 . The inner body  26  includes: an air-tight sealing part  27  projecting inward from the lower portion of it and a threaded part formed on the upper portion of it. An elastic member  28  is installed under the air-tight sealing part  27 . 
     The inner body  26  is coupled with an outer body  21 . The outer body  21  includes: a flange  22  extending outward; a threaded part formed on the inside thereof; and steps  23  for accommodating first and second filtering nets  24  and  25 . 
     The inner and outer bodies  26  and  21  are threadably coupled together, and therefore, they are detachable from each other. 
     A guide member  30  is installed on the second filtering net  25 , and the member  30  includes: a guide  31  having a cylindrical shape to guide grooves  32  formed on the cylindrical wall of the guide  31 ; and a pair of pinions  33  installed within the guide  31 . 
     An openable/closable device actuating member  40 , which is inserted into the guide  31  to move up and down, includes a floating device  41  to ascend owing to the floating force or to descend owing to the self-gravity. The floating device  41  has a through-hole  43  for accommodating the guide  31 , and racks  44  are formed on the lower portion of the through hole  43 , for being coupled with the pinions  33 . Further, a weight  42  is formed within the floating device  41 . 
     An openable/closable member  50  is partly inserted into the guide  31 . In the member  50 , racks  52  are formed to be coupled with the pinions  33 , and a movable bar  51  is formed under the racks.  52 , while a securing part  53  is formed under the movable bar  51 . A openable/closable plate  55  is attached to the bottom of the securing part  53 , and the plate  55  is a member of a reverse flow preventing device  54 . 
     Thus in the openable/closable member  50 , the securing part  53  and the reverse flow preventing device  54  are detachably coupled by means of bolts and the like. 
     Now another embodiment of the drainage reverse flow preventing apparatus according to the present invention will be described. 
     FIG. 8 is an exploded perspective view showing another embodiment of the drainage reverse flow preventing apparatus according to the present invention. FIG. 9 is a sectional view showing the assembled state of the drainage reverse flow preventing apparatus of FIG.  8 . FIGS. 10 a  and  10   b  are sectional views showing the reverse flow preventing action in the apparatus according to the present invention. 
     The round body  20  includes an outer body  21  and an inner body  26 . The outer body  21  has a flange  22  on the bottom of it, while the inner body  26  includes a threaded part. The outer and inner bodies  21  and  26  are threadably coupled together. The outer body  21  has steps  23  to accommodate first and second filtering nets  24  and  25 . Thus the filtering is carried out twice, and the outer and inner bodies  21  and  26  are detachable from each other. 
     Further, the inner body  26  includes: an air-tight sealing part  27  on the lower portion of it; and a setting part  29  for setting a guide member  30   a . An elastic member  28  is attached on the bottom of the inner body  26  to enhance the sealing. 
     The guide member  30   a  is placed on the  3 setting part  29  of the inner body  26 . The member  30   a  includes a guide  31   a  extending vertically, and the guide  31   a  has a hollow interior. 
     Further, the guide member  30   a  includes a round securing part  35 , and a supporting part  34  integrally links the guide  31   a  to the securing part  35 . 
     Between the securing part  35  and the supporting part  34 , there are formed draining holes  36  for efficiently draining waste water. Within the guide  31   a , there are installed pinions  33  which are rotatable forward and reverse. 
     An openable/closable device actuating member  40   a  includes a floating device  41   a  which ascends by the floating force and descends by the self-gravity. The floating device  41   a  accommodates the guide  31   a  by having a guide accommodating part  45 . 
     A weight  42  is press-fitted to the floating device  41   a . A securing part  53  is formed to be fastened to the guide accommodating part  45 . Under the securing part  53 , there is formed a movable bar  51  on which there-are formed racks  52  to be moved up and down depending on the revolution direction of the pinions  33 . 
     An openable/closable member  50   a  opens and closes the air-tight sealing part  27 . The member  50   a  is accommodated within the guide  31   a  to slide up and down. The member  50   a  includes: racks to be meshed with the pinions  33 ; a pair of slots to be engaged with the hooking devices  57 ; and a passive body  59  having guide grooves  58  with the same size to each other. 
     Owing to the guide grooves  58 , the shafts of the pinions  33  are not impeded when the floating device  41   a  moves up and down. 
     An openable/closable plate  55   a  is fixed to the bottom of the passive body  59 . The hooking devices  57  are formed at the center of the plate  55   a , and the hooking devices  57  are inserted into the guide  31   a  to be engaged with the slots of the inside of the passive body  59 . 
     An elastic member  56  is installed on the bottom of the plate  55   a  to reinforce the sealing of the air-tight sealing part  27 . 
     Now the action of the apparatus of the present invention will be described. 
     The drainage reverse flow preventing apparatus according to the present invention is applicable not only to the underground draining channels, but also to the kitchen sink and the veranda draining holes. Further, the apparatus can be used at a pipe where oil flows. 
     The shape of the body  20  of the apparatus is not limited to the round shape, but can be varied to rectangular or any other shape depending on the shape of the draining hole  60 . 
     First, the state of the draining of waste water through the apparatus of the present invention will be described. 
     As shown in FIGS. 6 and 7 a , when water or waste water is introduced into the body  20  of the apparatus, the floating device  41  floats due to the floating forces of the introduced water. 
     Therefore, the pinions  33  which is meshed with the racks  44  are rotated, and therefore, the racks  52  together with the movable bar  51  descends. 
     Therefore, the reverse flow preventing device  54  which is fastened to the bottom of the securing part  53  departs from the air-tight sealing part  27 , thereby opening the lower portion of the round body  20  In this manner, the introduced water flows efficiently through the apparatus. 
     When the draining is carried out in this manner, the flowing water imposes a pressure onto the reverse flow preventing device  54 , and.therefore, the floating force and the water pressure are combined to completely open the reverse flow preventing device  54  from the air-tight sealing part  27 . 
     Accordingly, the draining is more efficiently carried out. 
     The reason why the first and second filtering nets are installed is to filter off various foreign materials. 
     Now the state of preventing the reverse flow of waste water or foul odors by the apparatus of the present invention will be described in detail below. 
     When waste water is not introduced into the round body of the apparatus of the present invention, the floating device  41  descends owing to the self-gravity. Under this condition, owing to the racks  44  of the floating device  41 , the pinions  33  of the guide  31  are rotated. 
     Therefore, when the floating device descends, the movable bar  51  rises owing to the racks  52  of the movable bar  51 . 
     Accordingly, the reverse flow preventing device  54  closely contacts to the airtight sealing part  27 , thereby closing the lower portion of the round body  20 . Therefore, any reverse flow of waste water or foul odors is prevented. 
     Meanwhile, in raining seasons, if the draining holes overflow due to reverse flows through the draining conduit, the reversely flowing water pushes up the reverse flow preventing device  54 , that is, lifts up the openable/closable plate  55 . Therefore owing to the water pressure, the reverse flow preventing device  54  is closely contacted to the air-tight sealing part  27 , thereby preventing the reverse flow. 
     The elastic member  28  of the air-tight sealing part  27  and the elastic member  56  of the openable/closable plate  55  enhance the contacting between the reverse flow preventing device  54  and the air-tight sealing part  27 , thereby improving the sealing state and maximizing the prevention of the reverse flow. 
     Now the draining through the second embodiment of the apparatus of the present invention will be described in detail below. 
     When waste water is introduced into the round body  20  of the apparatus, the floating device  41   a  floats owing to the floating force of the introduced water Therefore, the movable bar  51  moves up together with the floating device  41   a , while the pinions  33  are rotated because they are meshed with the racks  44 . 
     When the pinions  33  are rotated, the passive body  59  descends owing to the racks which are meshed with the Pinions  33 . As a result, the openable/closable plate  55   a  which is fixed to the passive body  59  departs from the air-tight sealing part  27 , thereby opening the lower portion of the round body  20  of the apparatus. Thus the introduced water is efficiently drained into the draining hole  60 . 
     When the introduced water flows through the round body  20  into the draining hole  60 , the flowing water exerts a pressure onto the openable/closable plate  55   a , and therefore, the floating force and the water pressure are combined to completely open the openable/closable plate  55   a  from the air-tight sealing part  27 . 
     Therefore, the draining of the water is more efficiently carried out. 
     The reason why the first and second filtering nets  24  and  25  are installed in dual is to filter off various foreign materials. 
     Now the state of preventing the reverse flow of water or foul odors by the apparatus of the present invention will be described in detail below referring to FIG. 10 b.    
     If there is no water or waste water incoming into the round body  20  of the apparatus of the present invention, then the floating device  41   a  descends owing to the self-gravity. At the same time, the movable bar  51  which is fixed to the floating device  41   a  descends together with the floating device  41   a . Therefore, owing to the racks  52 , the pinions  33  are rotated. 
     When the pinions  33  are rotated, the passive body  59  ascends owing to the racks which are outwardly meshed with the pinions  33 . Therefore, the openable/closable plate  55   a  ascends to closely contact with the air-tight sealing part  27 , thereby closing the lower portion of the round body  20 . 
     Accordingly, any reverse flow of water or foul odors is prevented. 
     Meanwhile, in raining seasons, if the draining holes overflow due to reverse flows through the draining conduit, the reversely flowing water pushes up the openable/closable plate  55   a . Therefore owing to the water pressure, the reverse flow preventing device  54  is firmly and closely contacted to the air-tight sealing part  27 , thereby preventing the reverse flow. 
     The elastic member  28  of the air-tight sealing part  27  and the elastic member  56  of the openable/closable plate  55   a  enhance the contacting between the openable/closable plate  55   a  and the air-tight sealing part  27 , thereby improving the sealing state and maximizing the prevention of the reverse flow. 
     According to the present invention as described above, the water draining is efficiently carried out, thereby solving the overflow problem. Further the reverse flow of the waste water or foul odors can be prevented, and therefore, the environment is prevented from being polluted or contaminated. Further, in raining seasons, the flooding due to the reverse flow through draining holes can be prevented.

Summary:
An apparatus for preventing reverse flows in a drainage is disclosed. In this apparatus, a floating device ( 41 ) and a reverse flow preventing device ( 54 ) act mutually in opposite directions owing to the floating force and the water pressure, and thus the bottom of the round body ( 20 ) of the apparatus is automatically opened and closed, so that the drainage can efficiently work, and the waste water and the draining water with foul odors can be prevented from flowing reversely. The apparatus for preventing reverse flows of waste water according to the present invention includes a round body ( 20 ) to be installed in a drain hole ( 60 ). A guide member ( 30 ) is installed on a second filtering net ( 25 ) of the top of the round body ( 20 ), and has a guide ( 31 ) at the center of it. An openable/closable device actuating member ( 40 ) is insertingly installed on the guide member ( 30 ), for moving up and down along the guide ( 31 ) owing to the floating force and the self-gravity. An openable/closable member ( 50 ) is installed on the guide member ( 30 ), for causing an air-tight sealing part to be opened and closed by being oppositely interlocked to the openable/closable device actuating member ( 40 ).