Abstract:
A sliding device for a storage case is provided which is durable and provides a smooth sliding motion even in environments, such as those encountered in a refrigerator, wherein the storage case is subjected to humid, cold (below the freezing point) conditions. The sliding device comprises a fixed rail fixedly mounted to an inner side surface of the storage case and having a roller coupling portion in which a first set of rollers are rollably received; a movable rail fixedly mounted to an outer side surface of the storage container and having a roller coupling portion in which a set of second rollers are rollably received; and a middle rail which is slidably mounted between the fixed rail and the movable rail so as to provide a coupling relationship therebetween which guides the rolling motion of the first and second rollers. The fixed rail, the movable rail and the middle rail, as well as the rollers, are made of an injection molded plastic.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a sliding device for a storage case, and, more particularly, to a sliding device which can slide smoothly when mounted inside a storage case, such as a refrigerator, in a humid and cold (freezing) environment.  
           [0003]    2. Description of Related Art  
           [0004]    To promote smooth movement backward and forward of a heavy storage container containing a storage case with goods therein, sliding devices are provided on both outer side surfaces of the storage container and both inner side surfaces of the storage case.  
           [0005]    Such sliding devices typically include a fixed rail, a movable rail, a plurality of balls, and a supporting means for the balls mounted on an inner side surface of the storage case. The fixed rail extends over its full length in the sliding direction of the storage container. The movable rail is mounted to an outer side surface of the storage container in alignment with the fixed rail and slides along the fixed rail. The plurality of balls are located between the fixed rail and the movable rail.  
           [0006]    The fixed rail and the movable rail are made from roll formed metal plates. The rails are formed with concave guiding grooves for receiving the balls therein. The balls roll along the guiding grooves while closely contacting the grooves.  
           [0007]    When this type of sliding device is used in a storage case for storing foods, the metal rails and balls may oxidize, i.e., rust, since the component parts of the sliding device are exposed to moisture. Thus, the rolling motion of the balls is eventually impaired and it becomes troublesome to open or shut the storage container. That is, if the guiding grooves and the small rolling balls become rusty, the sliding motion of the storage container is impaired and the life of the sliding device is shortened.  
           [0008]    Further, when this type of sliding device is used in a storage case for a refrigerator or the like which is kept humid and cold, i.e., at a temperature below the freezing point, moisture is condensed and frozen on the rails or the balls, thereby impeding the sliding motion of the storage container.  
           [0009]    Finally, because the fixed rail and the movable rail are made by roll formed metal plates, the manufacturing cost of these rails is high.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention concerns a sliding device for a storage case which is constructed to solve the problems discussed above.  
           [0011]    It is an object of the present invention to provide a sliding device for a storage case which does not rust but which provides a smooth sliding motion even when the storage case is kept humid and cold (below the freezing point) and granular ice is formed on rails.  
           [0012]    It is another object of the present invention to provide a sliding device for a storage case which is durable and can be manufactured more easily and cheaply than conventional devices used for the same purposes.  
           [0013]    In accordance with the invention, a sliding device is provided for providing sliding backward and forward movement of a drawer-type storage container relative to a storage case, the storage container being slidably mounted inside the storage case, and the sliding device comprising: a first plurality of rollers; a second plurality of rollers; a fixed rail fixedly mounted to an inner side surface of the storage case and including a roller coupling portion rollably receiving the first plurality of rollers; a movable rail fixedly mounted to an outer side surface of the storage container and including a roller coupling portion rollably received in the second plurality of rollers; and a middle rail slidably mounted between the fixed rail and the movable rail for providing a coupling relationship therebetween and for guiding the rolling motion of the first and second plurality of rollers, such that the movable rail and the storage container slide together by means of a rolling motion of the second plurality of rollers along the middle rail, and the middle rail slides along the fixed rail by means of a rolling motion of the first plurality of rollers.  
           [0014]    Preferably, the middle rail further comprises an upper rail portion, including an upper channel for receiving the roller coupling portion of the movable rail therein and for guiding the sliding motion of the movable rail, a lower rail portion including a lower channel for receiving the roller coupling portion of the fixed rail therein and for guiding the sliding motion of the middle rail, and a partition rail portion integrally connecting the upper rail portion and the lower rail portion while partitioning the upper channel from the lower channel, and the fixed rail includes guiding space receiving the upper rail portion and the movable rail includes a guiding space for receiving the lower rail portion.  
           [0015]    Advantageously, the upper rail portion of the middle rail opens toward the roller coupling portion of the movable rail, and the lower rail portion of the middle rail opens toward the roller coupling portion of the fixed rail.  
           [0016]    Preferably, first movement restricting means are located between the fixed rail and the middle rail for restricting the movement of the middle rail, and second movement restriction means are located between the middle rail and the movable rail for restricting the movement of the movable rail.  
           [0017]    Advantageously, the first and second movement restricting means each include hooking members and respective openings for receiving the hooking members therein.  
           [0018]    Preferably, the hooking members protrude upwardly from the upper end surface of the middle rail and downwardly from the lower end surface of the middle rail, and the openings extend longitudinally of the fixed rail and at the movable rail, respectively.  
           [0019]    Advantageously, a plurality of slots are formed in the roller coupling portions of the fixed rail and movable rail, respectively, such that the first plurality of rollers and the second plurality of rollers extend through the slots and undergo rolling motion in contact with the corresponding partition rail portion.  
           [0020]    Preferably, the partition rail portion includes guiding grooves extending of the partition rail portion for guiding the rolling motion of the first and second plurality of rollers.  
           [0021]    Advantageously, the invention further comprises a first roller supporting member within which the first plurality of rollers are disposed in series and a second roller supporting member within which the second plurality of rollers are disposed in series, the first roller supporting member being disposed in the roller coupling portion of the fixed rail and the second roller supporting member being disposed in the roller coupling portion of the movable rail.  
           [0022]    Preferably, the movable rail is comprised of an injection molded plastic, the fixed rail is comprised of an injection molded plastic, the middle rail is comprised of an injection molded plastic, and the rollers are comprised of an injection molded plastic.  
           [0023]    Further features and advantages of the present invention will be set forth in, or apparent from, the detailed description of preferred embodiments thereof which follows. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate a preferred embodiment of the invention, and, together with the description which follows, serve to explain the principles of the invention:  
         [0025]    [0025]FIG. 1 is a perspective view of a refrigerator containing a sliding device for a storage case in accordance with a preferred embodiment of the present invention.  
         [0026]    [0026]FIG. 2 is an exploded perspective view of a sliding device for the storage case.  
         [0027]    [0027]FIG. 3 is an exploded perspective view of detailed structures of respective component parts of the embodiment of the sliding device as shown in FIG. 2.  
         [0028]    [0028]FIG. 4 is a cross-sectional view of component parts of the embodiment of the sliding device shown in FIG. 3 in an assembled state.  
         [0029]    [0029]FIG. 5 is a side-sectional view of an embodiment of the sliding device wherein the storage container is in a closed position.  
         [0030]    [0030]FIG. 6 is a side-sectional view of an embodiment of the sliding device wherein the storage container is in a half-closed position.  
         [0031]    [0031]FIG. 7 is a side-sectional view of an embodiment of the sliding device wherein the storage container is in a fully opened position. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0032]    A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.  
         [0033]    Referring to FIG. 1, a refrigerator for keeping foods in cold storage is shown which comprises an insulated main body  10  and a storage chamber  11 . The storage chamber  11  is open at its front portion. Slidably mounted inside the storage chamber  11  are one or more drawer-type storage containers  12  which are typically filled with food. This slidably mounting is provided by a pair of sliding devices; one sliding device, is denoted  20  and the other corresponding sliding device is hidden from view on the opposite side of the storage container  12 . The two sliding devices are collectively referred to as sliding devices  20  hereinbelow. The sliding devices  20  enable the storage containers  12  to slide backwardly and forwardly and, as explained below, are mounted on the storage chamber  11  and the corresponding storage container  12 .  
         [0034]    As shown in FIG. 2, each sliding device  20  comprises a fixed rail  30  which is fixedly mounted to an inner side surface of the storage chamber  11  of the refrigerator body  10 . The fixed rail  30  extends axially outwardly from this surface in the direction of a sliding motion of the storage container  12 . A movable rail  40  is mounted on an outer side surface of the storage container  12  so as to slide along the fixed rail  30 . A middle or intermediate rail  50  is slidably mounted between the fixed rail  30  and the movable rail  40  and provides coupling shown between the fixed rail  30  and the movable rail  40 . Because each of the pair of sliding devices  20  mounted on opposite sides of the storage container  12  is of the same construction, only one sliding device will be described hereinafter in detail.  
         [0035]    Referring to FIGS. 3 and 4, the fixed rail  30 , which is made of an injection molded plastic, includes a rail receiving portion  38  which has a flattened C-shaped traverse cross section. The rail receiving portion  38  includes a guiding space  33  and a roller coupling portion  32 . The roller coupling portion  32  extends downward from the rail receiving portion  38  to form a receiving space  32   a  into which a first plurality of rollers  31  are received. An upper rail portion  51  of the middle rail  50 , which is described hereinbelow, is slidably received in the guiding space  33  of the rail receiving portion  38 . The rollers  31  are disposed in series in a roller supporting member  34 . The roller supporting member  34  is of a predetermined length and is open at its upper and lower portions. The roller supporting member  34  receiving the rollers  31  therein is received in the receiving space  32   a  of the roller coupling portion  32 .  
         [0036]    The movable rail  40  is of the same construction as the fixed rail  30 , and is mounted on a side surface of the storage container  12  so as to slide with the storage container  12 . The movable rail  40  includes a roller coupling portion  42  at an upper portion thereof, and a rail receiving portion  48  at a lower portion thereof. Accordingly, the roller coupling portion  42  and the rail receiving portion  48  of the movable rail  40  are disposed in a reversed orientation with respect to the corresponding portions  32  and  38  of the fixed rail  30 .  
         [0037]    A second plurality of rollers  41  is disposed in series in a roller supporting member  44 . The coupling structure thereof corresponds to the coupling structure of the rollers  31 . The roller supporting member  44 , with the second rollers  41  received therein, is inserted into, i.e., received in, a receiving space  42 a of the roller coupling portion  42  of the movable rail  40 .  
         [0038]    The first and second rollers  31  and  41 , which are respectively mounted on the fixed rail  30  and the movable rail  40 , as well as the roller supporting members  34  and  44 , are made of an injection molded plastic. This prevents sliding device  20  from becoming rusty when used in the humid storage chamber  11  of a refrigerator or the like. Accordingly, the storage container  12  slides smoothly, and, moreover, the sliding device  20  can be easily manufactured.  
         [0039]    The middle rail  50  has an S-shaped transverse cross section and is coupled to the fixed rail  30  and movable rail  40 . The middle rail  50  includes an upper rail portion  51  formed with an upper channel  52  for receiving the roller coupling portion  42  of the movable rail  40 , and for guiding the sliding motion of the movable rail  40 . The middle rail  50  also includes a lower rail portion  53  formed with a lower channel  54  for receiving the roller coupling portion  32  of the fixed rail  30  therein, and for enabling the middle rail  50  to slide by virtue of the rolling motion of the first rollers  31  of the fixed rail  30 . Additionally, a partition rail portion  55  connects the upper rail portion  51  with the lower rail portion  53  and forms a partition between the upper channel  52  and the lower channel  54 . The partition rail portion  55  is formed between the upper and lower rail portions  51  and  53 . In other words, the upper channel  52  and the lower channel  54  are respectively disposed above and below the partition rail portion  55 . The middle rail  50  is also made of an injection molded plastic.  
         [0040]    After the fixed rail  30  and the movable rail  40  are coupled to the middle rail  50 , the upper rail portion  51  of the middle rail  50  is slidably inserted into the guiding space  33  of the rail receiving portion  38  of the fixed rail  30 , as shown in FIG. 4. Further, the lower rail portion  53  of the middle rail  50  is slidably inserted into the guiding space  43  of the rail receiving portion  48  of the movable rail  40 . In addition, the roller coupling portion  32  of the fixed rail  30  is disposed in the lower channel  54  of the middle rail  50 , and the roller coupling portion  42  of the movable rail  40  is slidably disposed in the upper channel  52 .  
         [0041]    Slots  35  and  45 , through which the rollers  31  and  41  pass, are formed lengthwise at the corresponding roller coupling portions  32  and  42  of the fixed rail  30  and the movable rail  40 , respectively so that the first and second rollers  31  and  41  can roll when in contact with the partition rail portion  55  of the middle rail  50  when the rails  30 ,  40  and  50  are assembled as aforementioned. Stated differently, the first and second rollers  31  and  41  protrude toward the respective guiding spaces  33  and  43  through the slots  35  and  45  formed at the fixed and movable rails  30  and  40 , when the middle rail  50  is coupled to the fixed and movable rails  30  and  40 , and thus the first and second rollers  31  and  41  are disposed in contact with the partition rail portion  55  of the middle rail  50 . Guiding grooves  55   a  and  55   b  for guiding the rolling motion of the first and second rollers  31  and  41  are formed lengthwise at the upper and lower surfaces of the partition rail portion  55 , respectively.  
         [0042]    Each sliding device  20  further includes a first movement restricting means between the fixed rail  30  and the middle rail  50  and a second movement restricting means between the middle rail  50  and the movable rail  40  for restricting the movement of the middle rail  50  and for restricting the movement of the movable rail  40 , respectively. The first means, i.e., the means for restricting the movement of the middle rail  50 , includes an upper hooking member or hook  56  which protrudes upward from upper rear end portion of the upper rail portion  51  of the middle rail  50 , and protrudes from an upper opening  36 . The upper opening  36  extends lengthwise for a predetermined distance in an upper surface of the fixed rail  30 . Accordingly, as the middle rail  50  slides backwardly and forwardly, the upper hooking member  56  engages the front end of the upper opening  36 , thereby stopping movement of the middle rail  50 . The second means, i.e., the means for restricting the range of motion or moving distance of the movable rail  40  includes a lower hooking member  57  which protrudes downwardly from a lower front end portion of the lower rail portion  53  of the middle rail  50 , and protrudes from a lower opening  47 . The lower opening  47  extends lengthwise for a predetermined length in a lower surface of the movable rail  40 . Accordingly, as the moving rail  40  slides backwardly and forwardly, the lower hooking member  57  engages the rear end of the lower opening  47 , thereby stopping movement of the movable rail  40 .  
         [0043]    In operation, when the rails  30 ,  40  and  50  are assembled, i.e., coupled together as shown in FIG. 4, the storage container  12  is slidably mounted in the storage chamber  11  and the rails  30 ,  40  and  50  are located substantially one over another as shown in FIG. 5. The first rollers  31  are received in the lower channel  54  of the middle rail  50  and are supported by the roller coupling portion  32  (FIG. 4) of the fixed rail  30 . The first rollers  31  are located at a frontal open portion of the storage chamber  11 . The second rollers  41  are received in the upper channel  52  of the middle rail  50  and are supported by the roller coupling portion  42  (FIG. 4) of the moving rail  40 . As illustrated, the second rollers  41  are located at a rear closed portion of the storage chamber  11 . When the storage container  12  is pulled forwardly to open the same, the movable rail  40  which is mounted on the side surface of the storage container  12 , is moved forward. Consequently, the second rollers  41  of the movable rail  40  roll along the guiding groove  55   a  (FIG. 4) formed at the lower surface of the upper channel  52  of the middle rail  50 . Accordingly, movable rail  40  is moved forward with the storage container  12 . As shown in FIG. 6, when the storage container  12  is in a half opened position, the lower hooking member  57  of the middle rail  50  is located adjacent to a rear portion of the lower opening  47  of the movable rail  40 . The second rollers  41  move toward a front portion of the upper channel  52  which is disposed above the first rollers  31 . When the storage container  12  is pulled forward, the lower hooking member  57  of the middle rail  50  engages the rear end of the lower opening  47  of the movable rail  40  thereby stopping further movement of the movable rail  40 .  
         [0044]    If, at this stage, the storage container  12  is pulled forwardly, the lower hooking member  57 , with which the rear end of the lower opening  47  is engaged, is also pulled forwardly. Accordingly, the middle rail  50  moves forward with the storage container  12  while the first rollers  31  roll without moving.  
         [0045]    As shown in FIG. 7, when the middle rail  50  moves forwardly a predetermined distance corresponding to that at which the storage container  12  is fully opened, the upper hooking member  56  engages the front end of the upper opening  36  of the fixed rail  30 , thereby stopping the further movement of the middle rail  50 .  
         [0046]    If a user pushes the storage container  12  into the storage chamber  11  after putting food into or withdrawing food from the storage container  12 , the storage container  12  slides into the storage chamber  11  in an operation which is the reverse of that associated with pulling out the storage container  12 .  
         [0047]    During the sliding motion of the storage container  12  described above, the weight of the storage container  12  is transferred to the partition rail portion  55  of the middle rail  50  through the second rollers  41  of the movable rail  40 , and thereafter to the first rollers  31  of the fixed rail  30 . Finally, the weight of the container  12  is transferred to a side wall of the storage chamber  11  on which the fixed rail  30  is mounted.  
         [0048]    It will be understood from the foregoing that during the sliding motion of the sliding device  20 , the first and second rollers  31  and  41  contact and roll on the partition rail portion  55  of the middle rail  50 . Further, the weight of the storage container  12  is transferred proportionally to the first and second rollers  31  and  41 . This operation provides smoothing out of the sliding motion of the middle rail  50  and the movable rail  40  (see FIG. 4).  
         [0049]    Alternatively, the movable rail  40  and the middle rail  50  may be moved in reverse order or simultaneously. However, the fundamental operation of the respective rails  40  and  50  remains the same.  
         [0050]    Because the fixed rail  30 , the movable rail  40 , the middle rail  50  and the plural rollers  31  and  41  are made of an injection molded plastic, the sliding device  20  does not rust nor is device  20  prone to other problems associated with metal parts in a humid environment. Therefore, the device  20  can be used in the humid storage chamber  11  of a refrigerator or the like without impairing the operation of the sliding device  20 . Further, because the first and second rollers  31  and  41  roll with minimum contact in the guiding grooves  55   a  and  55   b  formed in the partition rail portion  55 , the rollers  31  and  41  can roll over granular ice which may be produced on a surface of the middle rail  50 , thereby ensuring smooth movement of the storage container  12 .  
         [0051]    Although the invention has been described above in relation to preferred embodiments thereof, it will be understood by those skilled in the art that variations and modifications can be effected in these preferred embodiments without departing from the scope and spirit of the invention.