Abstract:
A pipe-fastening structure for an evaporation valve having a housing and a gas extraction path formed within the housing comprises a cylindrical connecting member, fixed to the housing, with first engaging portion and an inner space, a stopper member having a cylindrical inner member and second engaging portion engaging with the first engaging portion in two stages, a variable member, formed at part of the inner member in a cylindrical shape with a diameter capable of enlargement, channels formed at the inner wall of the variable member, a pipe for connecting evaporation valves and a large diameter bulge section formed in the vicinity of an end of the pipe. Locations of the inner member other than the variable member fit closely with the cylindrical inner wall of the connecting member and the first and second engaging portions undergo first stage engagement.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an evaporation valve pipe fastening structure for preventing a pipe connecting evaporation valves from coming away from the valves. 
     2. Description of the Related Art 
     Conventionally, evaporation valves have been employed to prevent vapor within a fuel tank being discharged to outside and to prevent fuel within the fuel tank from flowing to outside. There has, however, been a tendency to provide such evaporation valves within fuel tanks, to take into consideration safety aspects at the time of vehicle collisions and to make the overall structure smaller. When a plurality of evaporation valves are provided within a related fuel tank, each evaporation valve is fixed to the inner wall of the fuel tank using a bracket and pipes connecting the evaporation valves are attached right next to the evaporation valves. There is therefore almost no fear of the pipes coming away and no problem regarding the force required to pull the pipes away. 
     However, recently, upper surfaces of fuel tanks have become complex in shape and there are therefore cases where connecting pipes cannot be connected directly next to the evaporation valves. There are also cases where connecting pipes are vertically attached at a lower side of a two-way valve when evaporation valves are connected to such valves. There are therefore cases where pipes may come away in a downward direction with the related art where pipes are attached transversely. It is therefore necessary to fix such pipes to the fuel tank using a supporting bracket when there is a possibility that a pipe may come away from the fuel tank in a downward direction. 
     SUMMARY OF THE INVENTION 
     As the present invention sets out to resolve the aforementioned points, it is the object of the present invention to provide a pipe fastening structure where a pipe is resistant to a large pulling force and will not come away even when it is attached at the lower side of an evaporation valve in a direction pointing straight downwards. 
     In order to achieve the aforementioned object, in the present invention, a pipe-fastening structure for an evaporation valve having a housing and a gas extraction path formed within the housing comprises a cylindrical connecting member, a stopper member, a variable member, channels, a pipe, and a large diameter bulge section. The cylindrical connecting member is fixed to the housing and has first engaging means formed at an outer wall and an inner space communicating with the gas extraction path. The stopper member has a cylindrical inner member and second engaging means engaging with the first engaging means in two stages, closely fitting with the inner and outer walls of the cylindrical connecting member. The variable member is formed at part of the inner member in a cylindrical shape with a diameter capable of enlargement. The channels are formed in the same circumferential direction at the inner wall of the variable member at a position midway in the axial direction. The pipe is for connecting evaporation valves. The large diameter bulge section is formed in the vicinity of an end of the pipe. Locations of the inner member other than the variable member fit closely with the cylindrical inner wall of the connecting member and the first and second engaging means undergo first stage engagement. The pipe and the stopper member are then moved with respect to the connecting member, the variable member fits closely with the inner wall of the connecting member, and the first and second engaging means undergo second stage engagement. 
     The connecting member can be fixed to the housing using fixing means formed separately from the housing, or can be formed integrally with the housing. 
     The variable member can comprise a multiplicity of arms and slits formed between the arms. 
     In the present invention, when the first and second engaging means undergo the first stage engagement and the second stage engagement, engagement is not released even if the stopper member is subjected to external force in a direction opposite to a direction of attachment of the stopper member. 
     The first engaging means can also comprise of a first raised portion, a first recess, a second raised portion and a second recess, formed in that order in the axial direction at the outer wall of the connecting member, and the second engaging means can be an engaging claw. 
     According to the evaporation valve pipe fastening structure of the present invention, a housing, connecting member in a fixed state, and a pipe are attached via a stopper member. The stopper member is provided in such a manner that it is not possible to pull the stopper member away from the connecting member, and it is ensured that the pipe cannot be drawn away from the evaporation valve by ensuring that the pipe attached to the stopper member cannot be pulled away from the stopper member. As a result, the pipe will not come away from the evaporation valve even if the pipe is attached at a position directly below the evaporation valve. 
     The pipe can therefore also be arranged directly below the evaporation valve in an economic manner because the use of a supporting bracket to support the pipe is no longer necessary as there is no fear of the pipe coming away from the evaporation valve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view showing an embodiment of an evaporation valve pipe fastening structure of the present invention; 
     FIG. 2 is an exploded perspective view of the essential parts of FIG. 1; 
     FIG. 3 is a cross-sectional view showing a connecting member used in the present invention with an O-ring installed; 
     FIG. 4 is a cross-sectional view showing the connecting member used in the present invention with the stopper member attached; 
     FIG. 5 is a cross-sectional view showing the stopper member used in the present invention with a pipe attached; and 
     FIG. 6 is a cross-sectional view showing a pipe fixed to the stopper member. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following is a description of the present invention based on the drawings. 
     FIG. 1 is a cross-sectional view showing an embodiment of an evaporation valve pipe-fastening structure of the present invention and FIG. 2 is an exploded perspective view of the essential parts of FIG.  1 . 
     As shown in FIG. 1, an evaporation valve  10  comprises a housing  12 , a space  14  formed in the lower part of the housing  12 , a gas extraction path  16  formed in the upper part of the housing  12  and opening to outside, a gas introduction hole  18  formed in the housing  12  and connecting the upper part of the space  14  and the outside of the housing  12 , a float  20  capable of moving vertically within the space  14 , a spring  22  for urging the float  20  upwards, a valve  24  formed at the center of the upper surface of the float  20 , a partition  26  defining the space  14  and the gas extraction path  16 , a valve seat  28  formed on the side of the partition  26  on the side of the space  14 , and a connecting path  30  formed positioned at the center of the valve seat  28  and connecting the space  14  and the gas extraction path  16 . 
     The foregoing evaporation valve  10  is well-known in the related art. When the float  20  is positioned at the bottom with no fuel flowing within the housing  12 , fuel gas is expelled through the gas extraction path  16  so that when fuel flows into the space  14  of the housing  12  so that the float  20  floats, the valve  24  closes the valve seat  28  and the flow of fuel into the gas extraction path  16  is prevented. 
     A cylindrical connecting member  32 , that is separate from the housing  12 , is fixed to the opening of the gas extraction path  16  using a well-known fixing method or fixing means such as fusing. An inner space  34  for communicating with the gas extraction path  16  is formed within this cylindrical connecting member  32 . A stopper wall  36  is formed at an end of the inner space  34  at the side that communicates with the gas extraction path  16  so as to project inwards from the inner part of the inner space  34 , and a hole  38  communicating with the gas extraction path  16  and the inner space  34  is formed at the center of the stopper wall  36 . A step  40  is also formed midway in the axial direction of the inner space  34 . This step  40  is set so that the inner diameter of the inner wall on the side of the stopper wall  36  is relatively small near the step  40 . 
     A first raised portion  42  is formed at the outer wall of the connecting member  32  at the side far from the stopper wall  36  and a second raised portion  44  is formed next to the first raised portion  42  at the side close to the stopper wall  36 . A first recess  46  is formed between the first raised portion  42  and the second raised portion  44  and a second recess  48  is formed on the opposite side from the first recess so as to sandwich the second raised portion  44 . The first raised portion  42 , second raised portion  44 , first recess  46  and second recess  48  constitute a first engaging means. This first engaging means is formed at two locations at the top and bottom as shown in FIG.  1  and FIG. 2 but can also be formed about the entire periphery of the outer wall of the connecting member  32 , and is by no means limited to this shape. 
     In this description, the cylindrical connecting member  32  is formed separately from the housing  12  but can also be formed integrally with the housing  12 . A case where the connecting member  32  is integrally formed with the housing  12  is shown as a connecting member  50  in FIG.  1 . This connecting member  50  has the same configuration as the connecting member  32 , differing only in that the stopper wall  36  of the connecting member  32  is formed integrally with the housing  12 , i.e. the connecting member  50  has the inner space  34  formed within, has the stopper wall  36  as a partition, for the inner space  34  and the gas extraction path  16 , and has a hole  38  at the center of the stopper wall  36 , for communicating between the gas extraction path  16  and the inner space  34 . The step  40  is also formed midway in the axial direction of the inner space  34 . The first raised portion  42 , first recess  46 , second raised portion  44  and second recess  48  are formed at the outer wall of the cylindrical connecting member  50 , in that order. 
     In the present invention, stopper member  52  separate to the connecting member  32  and the connecting member  50  are used for attachment. A stopper  52  comprises an inner member  54 , the outer wall of which fits within the inner wall of the cylindrical connecting member  32  or connecting member  50 , two or more outer members  56  positioned at the outer walls of the cylindrical connecting member  32  and connecting member  50 , and a connecting section  58  for connecting one end of the inner member  54  and one end of the outer member  56 . The outer wall of the cylindrical inner member  54  is set so as to fit with the inner wall of the connecting member  32 . 
     The inner member  54  is in contact with the outer members  56  in the circumferential direction at a position far away from the connecting section  58  but is not in contact with the outer members  56  at a position close to the connecting section  58 , i.e. a multiplicity of slits  60  are formed in the axial direction at the inner member  54  from a position midway in the axial direction to the position of the connecting section  58 , with arm sections  62  being formed between pairs of these slits  60 . 
     One or two of the arm sections  62  of the large number of arm sections  62  of the inner member  54  and the connecting section  58  are formed in an integral manner. A cylindrical section formed by the multiplicity of arm sections  62  is a discontinuous cylinder and can therefore have its internal diameter enlarged by the application of external pressure because the side of the connecting section  58  of the inner member  54  is formed of a multiplicity of slits  60  and arm sections  62 . A variable member can therefore be formed by changing the outer shape using the slits  60  and the arm sections  62 . Channels  64  are also formed at the inner walls at a midway position in the axial direction of each of the arm sections  62 . 
     At the outer member  56 , the opposite side of the connecting section  58  is a free end and this free end extends outwards past the end of the inner member  54 . Engaging claws  66  are integrally formed as second engaging means for engaging the first recess  46  and the second recess  48  at the wall surface at the inner side of the outer member  56  exceeding the end of the inner member  54 . The structure of the second engaging means is by no means limited to the engaging claws  66 . Slits  68  (FIG. 2) are also formed in the same direction as the slits  60  of the inner member  54  at the outer member  56  at a position from midway in the axial direction to the position of the connecting section  58 . 
     A bulge of a large diameter is formed near the end of a pipe  70  connecting evaporation valves  10 . The outer diameter of a bulge  72  is set to be larger than the inner diameter of the inner wall of the discontinuous cylinder formed by the large number of arm sections  62  of the inner member  54 . The inner diameter of the channels  64  of the discontinuous cylinder shape formed by the large number of arm sections is also set to be of such a size that the bulge  72  of the pipe  70  fits exactly into the channels  64 . 
     The following is a description of the order of assembly of the present invention. 
     When the housing  12  and the connecting member  32  are separate, the connecting member  32  is fixed to the opening of the gas extraction path  16  using well-known fixing means such as fusing, etc. Alternatively, the connecting member  50  is formed integrally with the housing  12 . The inner space  34  of the connecting member  32  and the connecting member  50  communicates with the gas extraction path  16  when the connecting member  32  or the connecting member  50  are fixed to the housing  12 . In this state, as shown in FIG. 3, an O-ring  76  is installed within the inner space  34  of the connecting member  32  or connecting member  50  using a jig  74 . The O-ring  76  is housed in a position so as to come into contact with the step  40  (refer to FIG.  4 ), i.e. the O-ring is prevented from entering further by the step  40 . 
     After this, a stopper  52  is attached to the connecting member  32  or the connecting member  50  from the side of the free end of the outer member  56 . During this time, the outer wall of the inner member  54  of the stopper member  52  fits with the inner wall of the connecting member  32 . When the stopper member  52  is then pushed in the direction of the connecting member  32  or connecting member  50 , the engaging claws  66  positioned at the inner side near the free end of the outer member  56  come into contact with and then pass the first raised portion  42  of the connecting member  32  or connecting member  50 , and then engage with the first recess  46  (FIG.  5 ). When the engaging claws  66  are engaged with the first recess  46 , the stopper member  52  is installed in such a manner as to not come away even when pulled. When the stopper member  52  is then pushed further inwards, the engaging claws  66  of the stopper member  52  can be installed past the second raised portion  44 . 
     As shown in FIG. 5, when the engaging claws  66  of the outer member  56  engage with the first recess  46 , at the inner member  54 , only locations of the outer wall communicating in the circumferential direction temporarily fit to a shallow depth with the inner wall of the connecting member  32  or the connecting member  50 . When the engaging claws  66  of the outer member  56  engage with the first recess  46  of the connecting member  32  or the connecting member  50 , the evaporation valve  10  can be supplied by a parts supplier to a manufacturer for assembly in a vehicle, etc. 
     At the manufacturer, as shown in FIG. 5, the pipe  70  formed with the bulge  72  near one end is inserted into the inner space of the inner member  54  of the stopper member  52 . The outer diameter of the bulge  72  of the pipe  70  is set to be larger than the inner diameter of the cylindrical shape formed by the large number of arm sections  62 . However, the slits  60  are formed between each of the arm sections  62  and, as shown in FIG. 5, the arm sections  62  do not fit with the inner wall of the connecting member  32 . Therefore, when the pipe  70  is inserted into the inner space within the inner member  54 , the pipe is inserted while the bulge  72  spreads out the large number of arm sections  62 . When the bulge  72  reaches the channels  64  formed in the arm sections  62 , the bulge  72  fits in the channels  64  and insertion of the pipe is complete. 
     In this state, the bulge  72  of the pipe  70  will not come away from the channels  64  of the arm sections  62  of the inner member  54 , providing that a large amount of external force is not applied, i.e. the pipe  70  and the arm sections  62  of the inner member  54  are in a temporarily fixed state. 
     If the pipe  70  is then inserted after this, the pipe  70  and the inner member  54  (stopper  52 ) are in a temporarily fixed state. The pipe  70  and the stopper member  52  therefore become integrated and move towards the side of the stopper wall  36  of the connecting member  32 . As a result of this movement, the engaging claws  66  of the stopper member  52  pass the second raised portion  44  and fit into the second recess  48  (FIG.  6 ). During this time, the end of the pipe  70  passes through the O-ring  76 . When the engaging claws  66  engage with the second recess  48 , it is preferable for the end of the pipe  70  to be installed in such a manner as to make firm contact with the stopper wall  36 , so that the pipe  70  does not move in the direction of insertion even if pushed in the direction of insertion. 
     When the engaging claws  66  engage with the second recess  48 , installation is such that the second recess  48  and the engaging claws  66  do not disengage even if the stopper member  52  is pulled. The stopper member  52  is therefore not pulled away from the connecting member  32  even if the stopper  52  is subjected to external force. 
     When the engaging claws  66  of the stopper  52  engage with the second recess  48  of the connecting member  32 , the outer wall of the arm sections  62  of the inner member  54  fits with the inner wall of the connecting member  32 . The arm sections  62  are therefore no longer opened up towards the outer side. The fitting of the bulge  72  of the pipe  70  into the channels  64  of the arm sections  62  of the inner member  54  is therefore maintained and the pipe  70  does not come away even if pulled away from the stopper  52 . The O-ring is sandwiched by the step  40  of the connecting member  32  and the end surface at the side of the proceeding tip of the inner member  54 . 
     When the engaging claws  66  of the stopper  52  engage with the second recess  48  of the connecting member  32 , the stopper  52  cannot be drawn away from the connecting member  32  fixed to the housing  12 , and the pipe  70  cannot be drawn away from the stopper  52 . The pipe  70  will therefore not come away from the housing  12  of the evaporation valve  10 .