Patent Publication Number: US-8118378-B2

Title: Rail assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a Continuation-in-part application of Ser. No. 11/590,473, filed 1 Nov. 2006, and entitled “AUTO-RETURNING TRACK DEVICE”, now pending. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a rail assembly, which has a desirable overall telescoped length of a rail assembly, stable structure, and strong strength. 
     2. Description of Related Art 
     A first conventional returnable rail device is illustrated in  FIG. 10 . An outer rail  70  has a T-shaped fixed unit  71  disposed on one end thereof such that the end of the outer rail  70  is enclosed. The fixed unit  71  has a slot  76  defined in a middle T-shaped stub thereof. Two sliding rails  77  are respectively disposed on two sides of the slot  76  and are parallel to the outer rail  70 . The sliding rail  77  has a buckling groove  771  disposed on a front end thereof. A movable unit  72  and a buckling unit  721  disposed in the slot  76  in the T-shaped stub. The movable unit  72  has two columns  73  disposed on the two sliding rails  77  such that the movable unit  72  slides in the sliding rails  77 . Two elastic units  74  are respectively mounted between the two columns  73  and the T-shaped unit  71 . The buckling unit  721  is connected to the movable unit  72 . The buckling unit  721  has a connecting portion defined in a top thereof. A guiding part  751  is disposed in the inner rail  75  for corresponding to the connecting portion of the buckling unit  721 . When the inner rail  75  is pulled outwardly, the guiding part  751  drives the movable unit  72  moved along the sliding rail  77  to the buckling groove  771 . The buckling unit  721  is fixed in the buckling groove  771  temporarily. The guiding part  751  is detached from the buckling unit  721 . Conversely, when the inner rail  75  is pushed into the outer rail  70 , the inner rail  75  is returned. When the guiding part  751  is contacted with the connecting portion of the buckling unit  721 , the buckling unit  721  is detached from the buckling groove  771  of the sliding rail  77 . The inner rail  75  is auto-returned due to an elastic force of the elastic units  74 . 
     A second conventional returnable rail device is illustrated in  FIG. 11 . An outer rail  80  has a T-shaped fixed unit  81  disposed on one end thereof such that the end of the outer rail  80  is enclosed. The fixed unit  81  has a sliding rail  87  defined in a top thereof. A buckling groove  871  is defined in a front end of the sliding rail  87 . A movable buckling unit  83  is mounted in the sliding rail  87 . The movable buckling unit  83  has a connecting groove  831  defined therein. The movable buckling unit  83  has two buckling columns disposed on a bottom thereof for receiving in the sliding rail  87 . The movable buckling unit  83  is able to slide in the sliding rail  87 . An elastic unit  82  is disposed between the movable buckling unit  83  and the T-shaped fixed unit  81 . A guiding part  841  is disposed on the inner rail  84  for corresponding to the connecting groove  831  of the movable buckling unit  83 . When the inner rail  84  is outwardly pulled, the guiding part  841  drives the movable buckling unit  83  moved along the sliding rail  87  to the buckling groove  871 . The movable buckling unit  83  is fixed in the buckling groove  871  temporarily. The guiding part  841  is detached from the movable buckling unit  83 . The inner rail  84  is outwardly pulled. Conversely, the inner rail  84  is pushed into the outer rail  80 . When the guiding part  841  is contacted with the connecting groove  831 , the movable buckling unit  83  is detached from the buckling groove  871 . The inner rail  84  is auto-returned due to an elastic force of the elastic unit  82 . 
     A third conventional returnable rail device is illustrated in  FIG. 12 . An outer rail  90  has a fixed unit  91  disposed on one end thereof such that the end of the outer rail  90  is enclosed. The fixed unit  91  has two sliding rails  92  respectively defined in two sided slots of the outer rail  90 . A movable buckling unit  93  is mounted in the sliding rails  92 . The movable buckling unit  93  has two columns  932  formed on two sides thereof. The two columns  932  are mounted in the sliding rails  92  such that the movable buckling unit  93  is able to slide in the sliding rail  92 . The sliding rail  92  has a buckling groove  971  defined in a front end thereof. The movable buckling unit  93  has an elastic unit  94  mounted between the two columns  932 . The movable buckling unit  93  has a connecting portion formed on a top thereof. The inner rail  95  has a guiding part  96  defined in an inner surface thereof for corresponding to the connecting portion of the movable buckling unit  93 . When the inner rail  95  is pulled outwardly, the guiding part  96  drives the movable buckling unit  93  moved along the sliding rail  92  to the buckling groove  971 . The movable buckling unit  93  is fixed in the buckling groove  971  temporarily. Conversely, the inner rail  95  is pushed into the outer rail  90 . When the guiding part  96  is contacted with the connecting portion of the movable buckling unit  93 , the movable buckling unit  93  is detached from the buckling groove  971 . The inner rail  95  is auto-returned due to an elastic force of the elastic unit  94 . 
     The above described three conventional returnable rail devices illustrated in  FIGS. 10-12 , the sliding rail is disposed in the fixed unit. 
     A length of the sliding rail is restricted by a length of the fixed unit. The movable unit/the movable buckling unit is mounted in the sliding rail, connected with the elastic unit, and buckled with the guiding part in the inner rail. When the inner rail is pulled outwardly, the guiding part drives the movable unit/the movable buckling unit moving along the sliding rail to the buckling groove. The movable unit/the movable buckling unit is fixed in the buckling groove temporarily. The movable unit/movable buckling unit slides in the sliding rail such that a sliding stroke of the movable unit/movable buckling unit is restricted. When a three-rails telescopic device is utilized, an outer rail is mounted with the fixed unit. When a returning stroke of the movable unit/movable buckling unit is increased, a length of the middle rail is decreased. A total length and a strength of the telescopic device is decreased. 
     The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional returnable rail device. 
     SUMMARY OF THE INVENTION 
     The main objective of the present invention is to provide a rail assembly, which has a desirable overall telescoped length of a rail assembly, stable structure, and strong strength. 
     To achieve the objective, the rail assembly in accordance with the present invention includes an outer rail, a middle rail, an inner rail, and a retrieving unit. The outer rail has an outer rail space for accommodating the middle rail, the inner rail, and the retrieving unit. 
     The middle rail slides in the outer rail space, and has a middle rail space for accommodating the inner rail. The inner rail is accommodated in the middle rail, and sliding in the middle rail space. 
     The retrieving unit is assembled on one end of the outer rail space, and comprises a fixing part, disposed in the outer rail space, such that one end of the outer rail space is made into a closed end, the other end is made into an opened end; a sliding rail, be formed by two sided slots of the outer rail at the opened end; a buckling projection, disposed on the outer rail in the outer rail space at the opened end and located between the outer rail and the middle rail such that the middle rail is not obstructed by the buckling projection and extends over the buckling projection; a moving part, disposed in the outer rail space, and sliding along the sliding track; a buckling mechanism, disposed on the moving part; at least one elastic part, disposed between the fixing part and the moving part; and a guiding part, disposed on the inner rail. When the moving part slides along the sliding track, the middle rail extends over the buckling projection to increase a sliding scope and a length of the middle rail. 
     The moving part has two first slots and two pivoted slots. The two first slots are disposed between the moving part and the outer rail. 
     The buckling mechanism includes a buckling part and an elastic-plate. 
     The elastic-plate has a plate with two columns and a plurality of an elastic-portion. The two columns are assembled on the two first slots. 
     A plurality of the elastic-portion are abutted against the wall of the moving part. Two pivoted rods of the buckling part are assembled in the two pivoted slots of the moving part, and two buckling rods of the buckling part is assembled in the two first slots of the moving part and seated on the elastic-plate. 
     The moving part has two receiving slots on the both sides and the fixing part also has two receiving slots on the both sides or between the fixing part and the outer rail. When the moving part slides in the outer rail space, the inner rail extends through the receiving slots and reaching the closed end of the outer rail, so as to increase a sliding scope and a length of the inner rail. Such that the rail assembly has a maximum length and strength. 
     At least one elastic part is located on an outer side of the receiving slots. 
     A buffer unit comprises a buffer part and a mechanism corresponding to the buffer part, and the buffer part generates a buffering function through the corresponding mechanism. 
     Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a rail assembly in accordance with the present invention; 
         FIG. 2  is an enlarged exploded perspective view of an actuating mechanism of the rail assembly in accordance with the present invention; 
         FIG. 3  is an assembled perspective view of the rail assembly in accordance with the present invention; 
         FIG. 4  is an enlarged assembled perspective view of a moving part and a buckling mechanism; 
         FIGS. 5-9  are side plane operational views of the rail assembly in accordance with the present invention; and 
         FIGS. 10-12  are conventional track devices in accordance with the prior arts. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings and initially to  FIGS. 1-4 , a rail assembly in accordance with the present invention comprises an outer rail  1 , a middle rail  4 , an inner rail  3 , and a retrieving unit  20 . 
     The outer rail  1  has an outer rail space  11  for accommodating the middle rail  4 , the inner rail  3 , and the retrieving unit  20 . The middle rail  4  extends in the outer rail space  11 , and has a middle rail space  41  capable of accommodating the inner rail  3 . The inner rail  3  is accommodated in the middle rail  4 , and extends in the middle rail space  41 . The retrieving unit  20  is assembled on one end of the outer rail space  11 , and comprises: a fixing part  25 , disposed in the outer rail space  11 , such that one end of the outer rail space  11  is made into a closed end  13 , and the other end is an opened end  12 ; a sliding rail  16 , disposed on the outer rail  1  in the opened end  12  of the outer rail space  11 ; a buckling projection  14 , disposed on the outer rail  1  in the outer rail space  11  at the opened end and located between the outer rail  1  and the middle rail  3 , such that the middle rail  3  is not obstructed by the buckling projection  14 ; a moving part  21 , disposed in the outer rail space  11  and sliding along the sliding rail  16 , in which the moving part  21  slides in the outer rail  11  through the sliding rail  16 , the moving part  21  have two first slots  213 , two pivoted slots  214 , and a wall  212 ; on the top of the moving part  21  having two receiving slots  211  defined therein; a buckling mechanism  2223  includes an elastic plate  22  and a buckling part  23 , the elastic plate  22  disposed between the two first slots  213  defined in the bottom of the moving part  21  and the outer rail  1 , at a front end of the elastic plate  22  having a plurality of the elastic portion  222  which make the elastic plate  22  into compressibility, and a rear end of the elastic plate  22  having a plate with two columns  221 ; at a front end of the buckling part  23  having two pivoted rods  234  which be disposed on the two pivoted slots  213 , and a rear end of the buckling part  23  be seated on the elastic plate  22 , such that the buckling part  23  be swinging at the two pivoted slots  213  and corresponding to the buckling projection  14 ; the buckling part  23  also having two connecting blocks  231  defined in a top thereof; a guiding part  31 , disposed on the inner rail  3  for corresponding to the two connecting blocks  231 ; at least one elastic part  24 , disposed between the fixing part  25  and the moving part  21 . 
     Referring to  FIGS. 5-9 , when the inner rail  3  is returned, the guiding part  31  is buckled with the buckling mechanism  2223 . When the rail is pulled outwardly, the guiding part  31  drives the moving part  21  moving along the sliding rail  16 . When the elastic plate  22  of the buckling mechanism  2223  is abutted against the buckling projection  14 , the elastic plate  22  is compressed. The buckling rods  233  of the buckling part  23  detached from the elastic plate  22  and buckled with the buckling projection  14 . The moving part  21  is fixed on the buckling projection  14  temporarily. Conversely, when the inner rail  3  is inwardly pushed, the guiding part  31  is abutted against the two connecting blocks  231  of the buckling part  23  to detach from the buckling projection  14 , such that the buckling part  23  be seated on the elastic plate  22 . The middle rail  4  is not obstructed by the buckling projection  14  and extends over it to increase a sliding scope and length of the middle rail  4 . 
     As shown in  FIGS. 5-9 , in the outer rail space  11 , two receiving slots  211 ,  251  are respectively disposed on two sides of the moving part  21  and the fixing part  21  or two receiving slots  251  are disposed between the fixing part  25  and the outer rail  1 , in which when the inner rail  3  extends through the receiving slots  211 ,  251  in the outer rail space  11  and reaches the closed end  13  of the outer rail  1 , such that a length of the inner rail  3  is the same as the outer rail  1 . 
     As compared with the prior art, in the retrieving unit  20  of the rail assembly of the present invention, the sliding rail  16  is disposed on the outer rail  1  at the opened end  12 , the moving part  21  slides along the sliding rail  16 , such that the travel of the moving part  21  is not limited by the fixing part  25 . The buckling projection  14  is disposed on the outer rail  1  at the opened end  12  and located between the outer rail  1  and the middle rail  3 , such that the middle rail  3  is not obstructed by the buckling projection  14  and effectively extends into the outer rail space  11  and close to the closed end  13  of the outer rail  1 . Furthermore, with the receiving slots  211 ,  251  designed on the retrieving unit  20 , the inner rail  3  can also be shrunk to the closed end  13  of the outer rail  1 . 
     The outer rail  1  has better accommodation features, so that the lengths of the middle rail  4  and the inner rail  3  can be increased. Thus, when the structure of the present invention is telescoped, it has a better total length, and the overall telescope ratio is increased. In the present invention, a buffer part  26  is further disposed, and the buffer part  26  and the retrieving unit  20  may be disposed on the same end or different ends of the outer rail  1 . The buffer unit comprises a buffer part  26  and a mechanism corresponding to the buffer part  26 , and the buffer part  26  generating a buffering function through the corresponding mechanism. 
     The buffer part  26  and the corresponding mechanism are connected together. Through the buffering function provided by the buffer part  26 , a shrinking speed of the elastic part  22  may be tempered. The buckling projection  14  is located between the outer rail  1  and the middle rail  4 , such that the middle rail  4  is not obstructed by the buckling projection  14  and effectively increases the sliding scope of the middle rail  4 . 
     Thus, a longer middle rail  4  may be adopted, such that the rail assembly has a better overall telescoped length. 
     Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.