Abstract:
A slide rail includes an inner slide, an intermediate slide, a rack and a positioning element. The intermediate slide is used for receiving the inner slide; a block is positioned at an end of the intermediate slide. The rack has a plurality of ball bearings. An end of the rack is resisted against the block. The positioning element includes a fixing portion mounted to the intermediate slide, and a resilient hook portion having an ear part, the ear part capable of resisting against the other end of the rack to locate the rack.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present invention generally relates to slide rails. Particularly, the present invention relates to a slide rail with a rack for ball bearings. 
         [0003]    2. Description of Related Art 
         [0004]    Slide rails are used for guiding objects, such as drawers, to be pulled into or out from bodies, such as furniture. There are several kinds of slide rails, some have ball bearings but others have not. Slide rails without ball bearings have lower costs than those having ball bearings and generally have two slides movable relative to each other. The two slides contact each other without ball bearings, which makes pushing and pulling of the slides difficult because friction between the slides. 
         [0005]    Slide rails having ball bearings are easy to be pulled or pushed, however, the slides are difficult to be installed if the racks are not fixed, which may cause the slides and the racks to be damaged. 
       SUMMARY 
       [0006]    In one embodiment, a slide rail includes an inner slide, an intermediate slide, a rack and a positioning element. The intermediate slide is used for receiving the inner slide, a block is positioned at an end of the intermediate slide. The rack has a plurality of ball bearings and is disposed between the inner slide and the intermediate slide. The rack is used for providing smooth movement between the inner slide and the intermediate slide. An end of the rack is resisted against the block. The positioning element includes a fixing portion mounted to the intermediate slide, and a resilient hook portion having an ear part, the ear part capable of resisting against the other end of the rack to locate the rack. 
         [0007]    Other advantages and novel features of the slide rail will become more apparent from the following detailed description of embodiments when taken in conjunction with the accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an exploded, isometric view of a slide rail in accordance with an exemplary embodiment of the present invention, the slide rail including a positioning element and an intermediate slide; 
           [0009]      FIG. 2  is an amplified, isometric view of the positioning element of  FIG. 1 , but viewed from another aspect; 
           [0010]      FIG. 3  is an assembled view of the positioning element and the intermediate slide of  FIG. 1 ; and 
           [0011]      FIGS. 4 and 5  are assembled views of  FIG. 1 , but showing two using states of the slide rail. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Referring to  FIG. 1 , a slide rail in accordance with an embodiment of the present invention includes a rack  20 , an inner slide  40 , an intermediate slide  60 , an outer slide  70 , and a positioning element  80 . 
         [0013]    The rack  20  is installed between the inner slide  40  and the intermediate slide  60 , for assisting relative motion between the inner slide  40  and the intermediate slide  60 . The inner slide  40 , together with the rack  20 , is generally received in the intermediate slide  60 , and the intermediate slide  60  is generally received in the outer slide  70 . 
         [0014]    The rack  20  includes a main part  22  and two flanges  24  perpendicularly extending in a same direction from opposite sides of the main part  22  respectively. The main part  22  includes two first guiding grooves  220 ,  222  stamped therefrom and respectively connected to the two flanges  24 , and a first flat part  224  connected between the first guiding grooves  220 ,  222 . The first guiding grooves  220 ,  222  are symmetrically connected to opposite edges of the first flat part  224 . The first flat part  224  is slightly raised from the first guiding grooves  220 ,  222 . A hole  226  is defined in one end of the first guiding groove  220 . A plurality of ball bearings  240  is rotatably mounted in each flange  24 . 
         [0015]    The inner slide  40  includes an inner portion  42  and two sidewalls  44  generally perpendicularly extending from opposite sides of the inner portion  42  respectively. Each of the sidewalls  44  is slightly concave to form a first slideway at an outer surface thereof. 
         [0016]    The intermediate slide  60  includes an intermediate portion  62 , two sidewalls  64  extending from opposite sides of the intermediate portion  62 , and a block  66 . The intermediate portion  62  includes two second guiding grooves  620  stamped therefrom and connected to the corresponding sidewalls  64 , and a second flat part  624  connected between the second guiding grooves  620 . The second flat part  624  is slightly raised from the second guiding grooves  620  that are symmetrically connected to opposite edges of the second flat part  624 . Each sidewall  64  is concave to form a second slideway  640  at an inner surface thereof. The block  66  includes a base mounted to an end of the intermediate portion  62 , and two arms  660  extending from opposite sides of the base. The arms  660  are attached to inner surfaces of the corresponding sidewalls  64 . A slot  626  is defined in the intermediate portion  62  at a junction of the second flat part  624  and one of the second guiding grooves  620 , a distance between the slot  626  and the block  60  is generally equal to a length of the rack  20 . 
         [0017]    The outer slide  70  includes an outer portion  72 , and two sidewalls  74  extending from opposite sides of the outer portion  72  respectively. The intermediate slide  60  is received in a space bounded by the outer portion  72  and the sidewalls  74 . 
         [0018]    Referring also to  FIG. 2 , the positioning element  80  is used for positioning the rack  20  in the intermediate slide  60 , and facilitating the relative motion of the rack  20  to the intermediate slide  60 . The positioning element  80  includes a fixing portion  82 , a bridge portion  84 , and a hook portion  86 . The fixing portion  82  is set at a first end of the bridge portion  84 , with two fixing holes  820  defined therein, for fixing the positioning element  80  to the intermediate slide  60 . The hook portion  86  is set at a second end of the bridge portion  84 , opposite to the fixing portion  82 . The bridge portion  84  is made of elastic material, thus the bridge portion  84  together with the hook portion  86  can be bent relative to the fixing portion  82 . The bridge portion  84  is connected to the fixing portion  82  via a slanting connection portion  840 . An angle between the fixing portion  82  and the connection portion  840  is unequal to that between the connection portion  840  and the bridge portion  84 , thus, the bridge portion  84  is not parallel to the fixing portion  82 . A vertical distance between the fixing portion  82  and the first end of the bridge portion  84  is slightly greater than that between the fixing portion  82  and the second end of the bridge portion  84 . The hook portion  86  is slanting to the bridge portion  84  but parallel to the fixing portion  82 . Two ears  860  perpendicularly extend in a same direction from opposite sides of a distal end of the hook portion  86  respectively. Each ear  860  has a sloped surface  862  facing the distal end of the hook portion  86 , and an upright surface  864  opposite to the sloped surface  862 . A plate  842  extends from a side of the bridge portion  84  at the second end. The plate  842  is slightly raised from the bridge portion  84 , and has two guiding parts  844  slantingly extending from opposite ends thereof respectively. A distal end of each guiding part  844  is lower than the plate  842 . 
         [0019]    Referring also to  FIG. 3 , in assembly, the positioning element  80  is installed on a surface, facing the outer slide  70 , of the intermediate slide  60  via rivets or screws  628  extending through the corresponding fixing holes  820  of the positioning element  80  to engage with the intermediate portion  62  of the intermediate slide  60 . The fixing portion  82  is attached to the intermediate portion  62 . The bridge portion  84  passes through the slot  626  of the intermediate slide  60 . The plate  842 , the hook portion  86 , and the ears  860  are located at the surface, facing the inner slide  40 , of the intermediate portion  62 . 
         [0020]    Referring also to  FIG. 4 , the rack  20  is inserted into the intermediate slide  60 . The first guiding grooves  220 ,  222  contact the second guiding grooves  620  of the intermediate slide  60 . The ball bearings  240  fixed in the flanges  24  contact the second slideway grooves  640  of the intermediate slide  60 , enabling smooth movement of the rack  20  relative to the intermediate slide  20 . The first flat part  224  of the rack  20  presses the sloped surfaces  862  of the ears  860  of the positioning element  80  and moves toward the block  66  of the intermediate slide  60 , until the end, opposite to the hole  226 , of the rack  20  touches the block  66 , and the end adjacent the hole  226  of the rack  20  rides over the ears  860  of the positioning element  80 . The ears  860  are restored, with the upright surface  864  thereof engaging with the corresponding end of the rack  20 , and the plate  842  passing through the hole  226  to enter into the rack  20 . Therefore, the rack  20  is fixed in the intermediate slide  60  due to the two ends thereof being respectively restricted by the block  66  of the intermediate slide  60  and the upright surface  864  of the ears  860  of the positioning element  80 . 
         [0021]    Referring also to  FIG. 5 , the inner slide  40  is inserted into the intermediate slide  60  through the end having the block  66 , of the intermediate slide  60 . The sidewalls  44  of the inner slide  40  contact the arms  660  of the block  66 , for guiding the inner slide  40  to be inserted into the intermediate slide  60 . Because the inner slide  40  is supported on the base of the block  66 , the inner slide  40  will not collide with first flat part  224  of the rack  20 , but keeps a slight distance from the rack  20 . The first slideways of the sidewalls  44  accommodate the ball bearings  240  of the rack  20 , for providing a smooth movement of the inner slide  40 . The inner slide  40  is inserted to a position where the corresponding end thereof contacts the guiding plate  844 . The inner slide  40  is further moved, until the plate  842  is pressed by the corresponding sidewall  44 , due to the guiding plate  844  of the positioning element  80 . The plate  842  together with the hook portion  86  is resiliently pressed to retract through the slot  626  of the intermediate slide  60 , the ears  860  of the positioning element  80  are disengaged from the first flat part  224  of the rack  20 . Thus, the rack  20  is unlocked. The inner slide  40  moves on, the corresponding first guiding groove  220  of the rack  20  instead of the corresponding sidewall  44  of the inner slide  40  resiliently presses the plate  842  of the positioning element  80 . 
         [0022]    The rack  20  is capable of being restricted between the block  66  and the positioning element  80 . After the rack  20  is restricted, the inner slide  40  can be easily inserted into the intermediate slide  60  because of the ball bearings  240 . Moreover, the inner slide  40  cannot collide with the rack  20  because the inner slide  40  is kept a slight distance from the rack  20  via being supported by the block  66 . 
         [0023]    The embodiments were chosen and described in order to explain the principles of the invention and their practical application so as to enable others skilled in the art to utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its spirit and scope. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein.