Abstract:
A refrigerator includes a main body having a storage chamber; a drawer type door; a first storage unit movable in association with closing and opening operations of the drawer type door, each of side walls of the first storage unit having a first roller supporting surface; a second storage unit having first roller members mounted to a front region of the second storage unit, the first roller members being seated on the first roller supporting surfaces of the first storage unit to enable rolling movement thereof, a protrusion extending downwardly from a bottom surface of the second storage unit, and second roller members provided on both sides of the second storage unit to move along guide surfaces provided on an interior of the storage chamber. The protrusion is configured to prevent the first roller members from laterally leaving the first roller supporting surfaces.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 14/513,638 filed on Oct. 14, 2014, which is a continuation of U.S. application Ser. No. 12/801,782 filed on Jun. 24, 2010, which issued as U.S. Pat. No. 8,864,249 on Oct. 21, 2014, which claims the benefit of Korean Patent Application No. 10-2009-0063642, filed on Jul. 13, 2009 in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    Embodiments of the present invention relate to a refrigerator having a first storage box in the form of a drawer inserted in and withdrawn from an inside of a freezing chamber and a second storage box disposed on the upper part of the first storage box, both of which are smoothly inserted and withdrawn. 
         [0004]    2. Description of the Related Art 
         [0005]    A refrigerator is an apparatus to preserve freshness of various groceries for a long time by supplying a cold air generated by a heat exchanger to a storage chamber sectioned into a freezing chamber and a refrigerating chamber. 
         [0006]    Recently, in order to offer consumers various conveniences, it has been suggested to provide a refrigerator structured in a manner that the refrigerating chamber mainly used for a short-time preservation of beverage and food is disposed at an upper part thereof while the freezing chamber mainly used for a longtime preservation of frozen food is disposed at a lower part thereof. 
         [0007]    The freezing chamber is mounted with a first storage box which receives foodstuffs to be preserved in a frozen state. The first storage box is usually fixed to a rear surface of a freezing chamber door and inserted and withdrawn like a drawer as the freezing chamber door is opened and closed. 
         [0008]    In addition, a separate storage box, that is, a second storage box is mounted at an upper part of the first storage box also to receive foodstuffs. The second storage box has a relatively low utility owing to its short withdrawal distance. Accordingly, a method of withdrawing the second storage box needs to be improved. 
       SUMMARY 
       [0009]    Therefore, it is an aspect to provide a refrigerator enabling storage boxes to be smoothly inserted to and withdrawn from a storage chamber thereof. 
         [0010]    Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention. 
         [0011]    In accordance with an aspect, a refrigerator includes a storage chamber, a door mounted at a front side of the storage chamber, a first storage box inserted and withdrawn like a drawer in association with the operation of the door, and a second storage box seated on an upper part of the first storage box to operate in a rolling motion, wherein the first and second storage boxes are equipped with a roller device to enable the rolling motion of the second storage box on the first storage box, and the roller device includes a first roller member mounted to the second storage box; a first roller supporting part formed at the first storage box to support a rolling motion of the first roller member thereon; a second roller member mounted to the first storage box to share the load of the second storage box together with the first roller member during insertion and withdrawal of the second storage box; and a second roller supporting part formed at the second storage box to support a rolling motion of the second roller member thereon. 
         [0012]    The first roller member may be mounted at both front ends of the second storage box, and the first roller supporting part is mounted at both upper ends of the first storage box corresponding to the first roller members. 
         [0013]    The second roller member may be mounted at an inner rear end of the first roller supporting part of the first storage box, and the second roller supporting part may be formed on a bottom surface of the second storage box corresponding to the second roller member. 
         [0014]    The second roller supporting part may have a separation prevention rib to restrain the second storage box from moving in lateral directions while the second roller member is rolling along the second roller supporting part. 
         [0015]    The refrigerator may further include a buffer member formed at a rear end of the first roller supporting part to restrict the rolling motion of the first roller member. 
         [0016]    The refrigerator may further include a rail device provided on both sides of the first storage box to enable insertion and withdrawal of the first storage box. 
         [0017]    The rail device may include rail housings mounted on both sides of an interior cabinet of the storage chamber and each equipped with a rack gear; static rails received in the rail housings; movable rails slid relative to the static rails; rail covers fixed to the movable rails while mounting the first storage box; and pinion gears meshed with the rack gears and fixed to the movable rails. 
         [0018]    A connection bar may be interposed between the pinion gears to minimize the movement of the first storage box in the forward and the backward direction during insertion and withdrawal of the first storage box. 
         [0019]    A gear tooth formed at a rear end of each of the rack gears may have a lesser height than the other gear teeth and may have any one of semicircular, triangular and cut shape. 
         [0020]    Gear teeth formed at a rear end of each of the rack gears may have gradually decreasing heights toward the rear end of the rack gear. 
         [0021]    In addition, an idle gear or a slip prevention rib may be formed at a rear end of each of the rack gears so as to prevent separation of the pinion gears. 
         [0022]    A buffer projection may be formed at a rear part of the door so restrict a forward movement of the second storage box during the rolling motion of the second storage box. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0024]      FIG. 1  is a perspective view of a refrigerator according to an embodiment; 
           [0025]      FIG. 2  is a sectional view of the refrigerator shown in  FIG. 1 ; 
           [0026]      FIG. 3  is an exploded perspective view of a first storage box and a rail device employed in the refrigerator of  FIG. 1 ; 
           [0027]      FIG. 4A  to  FIG. 4D  are perspective views showing various versions of a rack gear of the rail device shown in  FIG. 3 ; 
           [0028]      FIG. 5  is a perspective view showing the first storage box and a second storage box shown in  FIG. 1 ; and 
           [0029]      FIG. 6  to  FIG. 8  are longitudinal sectional views showing sequential processes to withdraw the first and second storage boxes shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
         [0031]    Referring to  FIG. 1  and  FIG. 2 , a refrigerator according to the embodiment includes a main body  10  constituting the exterior look of the refrigerator, and a storage chamber formed inside the main body  10  and opened to the front. The storage chamber may be divided into an upper space and a lower space by a partition  15 . Usually, the upper space is used as a refrigerating chamber  20  while the lower space is used as a freezing chamber  30 . 
         [0032]    Heat exchangers  24  and  34  and ventilation fans  25  and  35  are mounted at rear parts of the refrigerating chamber  20  and the freezing chamber  30 , respectively, in order to produce a cold air and supply the cold air separately to the refrigerating chamber  20  and the freezing chamber  30 . In addition, a machine chamber  36  is provided at a rear lower part of the main body  10 , including a compressor and a condenser to compress and condense a refrigerant and supply the refrigerant to the heat exchangers  24  and  34 . 
         [0033]    Doors  21  and  31  are mounted to front sides of the respective storage chambers  20  and  30  to selectively open and close the insides of the storage chambers  20  and  30 . More specifically, the door  21  may be side-by-side doors pivotably connected at the left and the right of the front side of the refrigerating chamber  20 . The freezing chamber door  31  may be a drawer-type door  31  withdrawn and inserted from and into the front side of the freezing chamber  30 . 
         [0034]    A plurality of guards  22  may be mounted to a rear surface of the refrigerating chamber door  21  in multiple layers for more convenient reception of foodstuffs. Also, a plurality of shelves  23  and receiving members in the form of a drawer, a basket or the like may be mounted in the refrigerating chamber  21 . 
         [0035]    A guard  32  is mounted to a rear surface of the drawer door  31 . In addition, a first storage box  40  and a second storage box  50  are provided to the freezing chamber  30 , which are inserted and withdrawn like a drawer according to opening and closing operations of the freezing chamber door  31 . Here, the second storage box  50  is seated on an upper part of the first storage box  40  to operate in a rolling motion. 
         [0036]    As the freezing chamber door  31  is opened and closed, the first storage box  40  is withdrawn and inserted by a rail device  60  mounted at both lateral sides thereof. As shown in  FIG. 3 , the rail device  60  includes a pair of rail housings  61 , rail units  65  received in the rail housings  61 , and rail covers  66  fixed to part of the rail units  65  while mounting the first storage box  1 . 
         [0037]    Accordingly, the rail housings  61  are mounted on both sides of an interior cabinet of the freezing chamber  30  and receive the rail units  65 . 
         [0038]    A rack gear  62  is formed at a lower end of each of the rail housings  61 . A pinion gear  67  is provided to move in mesh with an upper surface of the rack gear  62 . 
         [0039]    A connection bar  68  is linked between the pinion gears  67  of both sides as shown in the drawing. The connection bar  68  is adapted to restrain the first storage box  40  from moving forward and backward while being inserted and withdrawn. 
         [0040]    Each of the rail units  65  includes a static rail  65   a  fixed to each rail housing  61 , and a movable rail  65   b  slid along the static rail  65   a.  The static rail  65   a  and the movable rail  65   b  may be implemented by general rails performing a rolling motion by a bearing (not shown) provided therein and enabling insertion and withdrawal of the drawer-type door  31 . 
         [0041]    The pinion gear  67  meshed with the rack gear  62  formed at the rail housing  61  is fixed to the movable rail  65   b.  The rail cover  66  for mounting of the first storage box  40  is also fixed to the movable rail  65   b.  Additionally, a guide groove may be formed at the rail cover  66  to guide a guide projection  41  extended on both lateral sides of the first storage box  40 . 
         [0042]    While the pinion gear  67  is separated from and reset in the rack gear  62  according to insertion and withdrawal of the first storage box  40 , an operation noise may be generated due to surface contact between the pinion gear  67  and the rack gear  62  according to shape of teeth of the gears  62  and  67 . 
         [0043]    To minimize such an operation noise, the embodiment improves the teeth of the rack gear  62  so that the pinion gear  67  and the rack gear  62  achieve line-contact or point-contact with each other while the pinion gear  67  and the rack gear  62  are being reset. 
         [0044]    More specifically, the teeth of the rack gear  62  may be configured in a manner that a gear tooth  62   a  formed at a rear end of the rack gear  62  has a semicircular shape with a lesser height than the other gear teeth, as shown in  FIG. 4A . The gear tooth  62   a  formed at the rear end of the rack gear  62  may have a triangular shape with a lesser height than the other gear teeth as shown in  FIG. 4B . The gear tooth  62   a  may have a partially cut shape to be slanted as shown in  FIG. 4C . A plurality of the gear teeth  62   a  may be formed to have gradually decreasing heights toward the rear end of the rack gear  62 . 
         [0045]    In case that the first storage box  40  is eccentrically inserted and withdrawn, one of the pinion gears  67  may be idly rotated. To this end, an idle gear  63   a  as shown in  FIG. 4A  or a slip prevention rib  63   b  as shown in  FIG. 4B  may be further provided at the rear end of each of the rack gears  62 . 
         [0046]    As aforementioned, the second storage box  50  is seated and rolled on the upper part of the first storage box  40 . For this, the first and second storage boxes  40  and  50  are equipped with a dedicated roller device enabling the rolling motion of the second storage box  50  on the first storage box  40 , as shown in  FIG. 5  and  FIG. 6 . 
         [0047]    The roller device includes a first roller member  51  mounted to the second storage box  50 , a first roller device having a first roller supporting part  42  formed at the first storage box  40  to seat the first roller member  51  thereon, a second roller member  43  mounted to the first storage box  40 , and a second roller device having a second roller supporting part  52  formed at the second storage box  50  to seat the second roller member  43  thereon. 
         [0048]    More particularly, the first roller member  51  is mounted at both front ends of the second storage box  50  whereas the first roller supporting part  42  is formed at both upper ends of the first storage box  40 . While seating the respective first roller members  51  thereon, the first roller supporting parts  42  support the second storage box  50  and guide the rolling motion of the first roller members  51  during insertion and withdrawal of the second storage box  50 . 
         [0049]    Here, a buffering member  44  is formed at a rear end of each first roller supporting part  42  to restrict the rolling motion of each first roller member  51  so that the first roller member  51  cannot roll beyond a predetermined degree, as well as absorbing the rolling motion. An undescribed reference numeral  32   a  denotes a buffering projection that restricts a forward movement of the second storage box  50 , while serving as a buffer between the guard  32  of the freezing chamber door  31  and the second storage box  50  during withdrawal of the second storage box  50 . 
         [0050]    The second roller member  43  is disposed at an inner rear end of each of the first roller supporting parts  42  to face a bottom surface of the second storage box  50 . Since the second roller members  43  share the load of the second storage box  50  with the first roller members  51  during insertion and withdrawal of the second storage box  50 , the second storage box  50  may be more smoothly moved forward and backward. 
         [0051]    In addition, the second roller supporting part  52  is formed on both bottom sides of the second storage box  50 , being each provided with a separate prevention rib  53  supporting each second roller member  43  to prevent the second storage box  50  from moving in lateral directions while the second roller member  43  is rolling along the second roller supporting part  52 . 
         [0052]    Also, a third roller member  57  is provided on both sides of the second storage box  50  to move along guide rails  37  formed in the interior cabinet of the freezing chamber  30  as the second storage box  50  is being inserted and withdrawn. More specifically, the third roller members  57  are mounted at front ends of flange parts  56  formed on both sides of the second storage box  50 . Therefore, the third roller members  57  support the rear end of the second storage box  50  when only the first storage box  40  is withdrawn but the second storage box  50  is not withdrawn. 
         [0053]    Hereinafter, the process of withdrawing the second storage box  50  according to the embodiment will be described. 
         [0054]    In order to withdraw the first and second storage boxes  40  and  50 , first, the freezing chamber door  31  is pulled out to the front of the refrigerator so that the first storage box  40  is withdrawn as shown in  FIG. 7 . Here, the first storage box  40  is withdrawn by the rail device  60  mounted at the both sides of the first storage box  40 . 
         [0055]    As the freezing chamber door  31  is pulled to the front, the pinion gear  67  is operated, which is meshed with the rack gear  62  formed on the rail housing  61  of the rail device, thereby sliding the movable rail  65   b  fixed to the pinion gear  67  relative to the static rail  65   a.  When the movable rail  65   b  is thus slid from the static rail  65   a,  the rail cover  66  fixed with the movable rail  65   b  is moved. Accordingly, the first storage box  40  mounted to the rail cover  66  is withdrawn to the front. 
         [0056]    Thus, the rail device is operated by the rack gear  62  of the rail housing  61  and the pinion gear  67  meshed with the rack gear  62  during insertion and withdrawal of the first storage box  40 . Here, since the teeth structure of the rack gear  62  is improved to form line-contact or point-contact with the pinion gear  67 , the operation noise may be prevented while the teeth of the pinion gear  67  are being separated from and reset in the teeth of the rack gear  67 . 
         [0057]    Furthermore, during insertion and withdrawal of the first storage box  40 , the idle gear  63   a  or the slip prevention rib  63   b  formed at the rear end of the rack gear  62  may prevent separation of the pinion gear  67  and accordingly prevent idle rotation of the pinion gear  67 . 
         [0058]    When the first storage box  40  is withdrawn, the second storage box  50  seated on the upper part of the first storage box  40  is also withdrawn. When a user intends to put certain stuff in the first storage box  40  in this state, the second storage box  50  needs to be inserted into the freezing chamber  30 . 
         [0059]    Insertion of the second storage box  50  may be achieved in the following manner as shown in  FIG. 8 . The first roller member  51  of the second storage box  50  is rolled along the first roller supporting part  42  formed at the first storage box  40 . Simultaneously, the second roller member  43  of the first storage box  40  is rolled along the second roller supporting part  52  formed at the second storage box  50 . 
         [0060]    While the second storage box  50  is rolling on the upper part of the first storage box  40  by the roller device, the load of the second storage box  50  is distributed to the first roller member  51  of the second storage box  50  and the second roller member  43  of the first storage box  40 . As a result, the second storage box  50  is smoothly rolled forward and backward. 
         [0061]    As is apparent from the above description, a refrigerator according to the embodiment of the present invention enables smooth insertion and withdrawal of storage boxes by adopting a roller device and a rail device. 
         [0062]    Although a few embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.