Abstract:
A synchronous system for a three-stage ball bearing slide includes a carrier track being inserted into a fixed track to carry a mobile track. Both of the mobile and the carrier tracks engage in reciprocal movement along the same axis direction in relation to the fixed track. A dancer is pivoted to the rear end of the carrier track. The carrier track synchronously slides with the mobile track by a protruding tongue on the mobile track upholding the dancer, and is held in position by having the dancer to uphold a compression bit on the fixed track. A direct push on the extreme where the carrier track is extended releases the dancer from the compression bit to retract once again the carrier track into the fixed track.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     (a) Field of the Invention  
         [0002]     The present invention relates to a synchronous system for a three-stage ball bearing slide, and more particularly, to a mobile track when pulled to extend drives a carrier track to slide synchronously and is temporarily positioned at its terminal without being retracted thus to permit the carrier track to be directly subject to the push thereon to once again be retracted into a fixed track.  
         [0003]     (b) Description of the Prior Art  
         [0004]     A conventional three-stage ball bearing slide usually contains a fixed track (outer track), a carrier track (middle track), and a mobile track (inner track). Taking the ball bearing slide adapted to a cabinet and its drawers for example, the fixed track (outer track) is fixed to the cabinet, the mobile track (the inner track) is each fixed to both sides of the drawer, and the carrier track (middle track) is inserted into the fixed track (outer track) by means of a slide aid, usually a ball bearing, to slide and carry the mobile track (inner track), thus to make the mobile track (inner track) and the carrier track (the middle track) engaging in reciprocal movement along the same axial direction in relation to the fixed track (outer track) for the drawer to be pulled out or in against the cabinet. The three-stage ball bearing slide of the prior as illustrated in  FIG. 13  of the accompanying drawings defines the track according to its location. Slide aids D, E are respectively provided between the inner track (A) and the middle track (B) as well as between the middle track (B) and the outer track (C). A retainer (F) and a compressor (G) are respectively provided in the inner track (A) and the middle track (B) to allow one-way positioning when the inner track (A) is pulled out to its extreme and to pull the retainer (F) to release it from the compressor (G) for the inner track (A) to disengage from the middle track (B).  
         [0005]     So far the development of the design of those ball bearing slides adapted to cabinets and drawers has been focusing on two purposes, to hold the carrier track (middle track) in positioning when pulled to its fully extended location, and to be pulled for movement synchronously with the mobile track (inner track). Design of the linking mechanism associated with those two purposes may be referred to U.S. Pat. Nos. 5,551,775 and 5,757,109; U.S. Published application Nos. 2002/0057042, 2003/0080659, 2003/0107309, and 2003/0111942; and Taiwan Utility Model Patent Nos. 215789 and 197034 (No. 197034 same as that of U.S. Published application No. 2003/0178922 owned by this Applicant).  
       SUMMARY OF THE INVENTION  
       [0006]     The primary purpose of the present invention is to provide a synchronous system for a three-stage ball bearing slide, wherein, a mobile track when pulled to extend links a carrier track to slide synchronously and is temporarily positioned at its terminal without being retracted thus to permit the carrier track to be directly subject to the push thereon to once again retract into a fixed track.  
         [0007]     To achieve the purpose, a dancer is pivoted to an arch surface of the rear end of the carrier track. The dancer is adapted with a plate in proper length flushed with the arch surface of the carrier track. An indention is formed on the rear of the plate and a wall facing the inner side of the mobile track is formed in front of the indention. A resisting bit facing the fixed track is provided behind the indention. Both of the wall and the resisting bit are facing each other and expanding outwardly at a certain oblique. A notch is provided in the rear of the carrier track to permit the insertion of the resisting bit of the dancer; and a hook is provided to the carrier track. The dancer keeps constant swing by having provided an elastic member connected between the hook and one side of a pivoted end of the dancer. A protruding tongue is provided on the inner side of the mobile track in relation to a space defined by the indention of the dancer, and a compression bit is provided on the inner side of the fixed track in relation to the rear end of the carrier track when pulled out. A shallow slot is provided on the edge of the compression bit in relation to the resisting bit of the dancer; thereby, the mobile track by extending its protruding tongue into the indention to hold against the wall, thus to link to and pull out the carrier track. The carrier track when pulled to its extreme is secured in position when the resisting bit of the dancer holds against the shallow slow of the compression bit to link the carrier track to be pulled out. Accordingly the positioning of the carrier track is released when subject to an externally applied push.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is an exploded view showing a preferred embodiment of the present invention.  
         [0009]      FIG. 2  is a top view showing an assembly of the preferred embodiment of the present invention.  
         [0010]      FIG. 3  is a first schematic view showing that the preferred embodiment of the present invention is pulled outwardly.  
         [0011]      FIG. 4  is a second schematic view showing that the preferred embodiment of the present invention is pulled outwardly.  
         [0012]      FIG. 5  is a third schematic view showing that the preferred embodiment of the present invention is pulled outwardly.  
         [0013]      FIG. 6  is a fourth schematic view showing that the preferred embodiment of the present invention is pulled outwardly.  
         [0014]      FIG. 7  is a fifth schematic view showing that the preferred embodiment of the present invention is pulled outwardly.  
         [0015]      FIG. 8  is a schematic view showing the final state of the preferred embodiment of the present invention when fully extended.  
         [0016]      FIG. 9  is an exploded view showing another preferred embodiment of the present invention.  
         [0017]      FIG. 10  is a top view showing the layout of the assembly of another preferred embodiment of the present invention.  
         [0018]      FIG. 11  is an exploded view showing another preferred embodiment yet of the present invention.  
         [0019]      FIG. 12  is a top view showing the layout of the assembly of another preferred embodiment yet of the present invention.  
         [0020]      FIG. 13  is an exploded view of a prior art.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     Referring to  FIG. 1 , the present invention relates to a synchronous system for a three-stage ball bearing slide. The ball bearing slide adapted to a preferred embodiment of the present invention is essentially having respectively disposed two slide aids ( 4 ) and ( 5 ) between a mobile track ( 1 ) and a carrier track ( 2 ) as well as the carrier track ( 2 ) and a fixed track ( 3 ) to facilitate sliding. A retainer ( 6 ) and a compressor ( 7 ) are respectively disposed on the inner side of the mobile track ( 1 ) and the front end of the carrier track ( 2 ). A protrusion ( 61 ) is adapted to the lower side of the retainer ( 6 ) and a retaining bit ( 71 ) is provided on either side of the compressor ( 7 ). Accordingly, when the mobile track ( 1 ) is pulled to its extreme, the retainer ( 6 ) has its protrusion ( 61 ) to uphold the retaining bit ( 71 ) of the compressor ( 7 ) to prevent the mobile track ( 1 ) from disengaging from the carrier track ( 2 ). A stopper ( 21 ) is each provided on two sides at the rear end of the carrier track ( 2 ) and a raised piece ( 31 ) is each disposed on the inner sides at the front end of the fixed track ( 3 ) so that the carrier track ( 2 ) is retained by the slide aid ( 5 ) by means of the stopper ( 21 ) and the slide aid ( 5 ) is further retained by the raised piece ( 31 ) to restrict the extension extreme of the carrier track ( 2 ) in relation to the fixed track ( 3 ) as illustrated in  FIG. 8 . It is to be noted that the structures of preventing disengagement disposed for the mobile track ( 1 ) in relation to the carrier track ( 2 ), and for the carrier track ( 2 ) in relation to the fixed track ( 3 ) are not the primary claims to be claimed under this application, nor the adapted structures absolutely required in this application; therefore, shall not restrict the scope of the claims to be claimed hereunder.  
         [0022]     The carrier track ( 2 ) in the preferred embodiment has an arch center in cross-section, and a dancer ( 8 ) is pivoted to the rear of the arch center. The dancer ( 8 ) contains a plate in proper length that is flushed on the arch center of the carrier track ( 2 ). A hole ( 81 ) is disposed at the front end of the plate to be inserted with a bolt ( 91 ) and riveted to a through hole ( 22 ) on the carrier track ( 2 ). An indention ( 82 ) is formed to the rear of the dancer ( 8 ) and a wall ( 83 ) facing the inner side of the mobile track ( 1 ) is formed in front of the indention ( 82 ). A resisting bit ( 84 ) facing the fixed track ( 3 ) is formed in the rear of the indention ( 82 ). The rear end of the wall ( 83 ) and the front end of the resisting bit ( 84 ) are facing each other and expanding outwardly at a certain oblique. A notch ( 23 ) is provided in the rear of the carrier track ( 2 ) to receive the insertion of the resisting bit ( 84 ) of the dancer ( 8 ). A hook ( 24 ) is provided on the carrier track ( 2 ) and a hanger ( 85 ) is formed on one side of a pivoted end of the dancer ( 8 ). An elastic member ( 92 ) is connected between the hook ( 24 ) and the hanger ( 85 ) to subject the dancer ( 8 ) to elastic pull for maintaining constant and automatic swing.  
         [0023]     A protruding tongue ( 11 ) is provided on the inner side of the mobile track ( 1 ) in relation to the space defined by the indention ( 82 ).  
         [0024]     A protruding compression bit ( 32 ) is disposed on the inner side of the fixed track ( 3 ) in relation to the rear end of the carrier track ( 2 ) when pulled out, and the edge of the compression bit ( 32 ) is provided with a shallow slot ( 321 ) in relation to the resisting bit ( 84 ) of the dancer ( 8 ).  
         [0025]     When the three-stage ball bearing slide is retracted as illustrated in  FIG. 2 , the mobile track ( 1 ) has its protruding tongue ( 11 ) extending into the indention ( 82 ) of the dancer ( 8 ) in the rear of the carrier track ( 2 ). Therefore, when the mobile track ( 1 ) is pulled and extended as illustrated in  FIGS. 3 and 4 , the mobile track ( 1 ) links the carrier track ( 2 ) to be pulled out by having the protruding tongue ( 11 ) to uphold the rear end of the wall ( 83 ) of the dancer ( 8 ). Once both of the mobile track ( 1 ) and the carrier track ( 2 ) are synchronously pulled out to reach the compression bit ( 32 ) of the fixed track ( 3 ) as illustrated in  FIGS. 4 and 5 , the dancer ( 8 ) swings by having the retaining bit ( 84 ) to climb and slide along the compression bit ( 32 ). As illustrated in  FIG. 6 , when the carrier track ( 2 ) extends to its extreme in relation to the fixed track ( 3 ), the retaining bit ( 84 ) of the dancer ( 8 ) falls into the shallow slot ( 321 ) at the edge of the compression bit ( 32 ) to provide a positioning function to prevent the carrier track ( 2 ) from being easily retracted in relation to the fixed track ( 3 ). The positioning strength is slightly greater than the slide resistance cast by the mobile track ( 1 ) in relation to the carrier track ( 2 ). Subsequently, the mobile track ( 1 ) is further pulled out as illustrated in  FIGS. 7 and 8 . The protruding tongue ( 11 ) of the mobile track ( 1 ) slightly pushes against the wall ( 83 ) of the dancer ( 8 ) before immediately disengaging from the indention ( 82 ) of the dancer ( 8 ) while the mobile track ( 1 ) is extended in relation to the carrier track ( 2 ) to finally complete the three-stage extension of the slide. According to the extension status with the mobile track ( 1 ) removed from the carrier track ( 2 ), even though the extended carrier track ( 2 ) is for the time being secured in the front end of the fixed track ( 3 ), the positioning status of having the retaining bit ( 84 ) of the dancer ( 8 ) secured in the shallow slot ( 321 ) of the compression bit ( 32 ) can be immediately released by slightly pushing in the carrier track ( 2 ), thus to retract the carrier track ( 2 ) to prevent it from becoming a sudden barrier without exercising too much efforts to pull the dancer ( 8 ).  
         [0026]     Whereas the strength exercised to secure the retaining bit ( 84 ) of the dancer ( 8 ) into the shallow slot ( 321 ) of the compression bit ( 32 ) is slightly greater than the slide resistance of the mobile track ( 1 ) in relation to the carrier track ( 2 ) in the process of retracting the mobile track ( 1 ) once again, the mobile track ( 1 ) is first retracted into the carrier track ( 2 ) and continues to move to force the retaining bit ( 84 ) of the dancer ( 8 ) to slide out of the shallow slot ( 321 ) of the compression bit ( 32 ) to automatically release the positioning of the carrier track ( 2 ) in relation to the fixed track ( 3 ) for both of the mobile track ( 1 ) and the carrier track ( 2 ) to be gradually retracted at the same time into the fixed track ( 3 ).  
         [0027]     Now referring to  FIGS. 9 and 10  for another preferred embodiment of the present invention adapted with a dancer that automatically maintains constant elasticity from the swing, a torsion spring ( 94 ) has its coil end penetrated by an axial bolt ( 93 ) to connect the torsion spring ( 94 ) to the dancer ( 8 ), and two legs of the torsion spring ( 94 ) respectively uphold against the inner side of the wall ( 83 ) of the dancer ( 8 ) and a fixation bit ( 25 ) on the carrier track ( 2 ) to achieve the same elastic function in relation to the dancer ( 8 ). In another preferred embodiment yet of the present invention as illustrated in  FIGS. 11 and 12 , an elastic rod ( 86 ) is forthwith extending from one side of the pivoted end of the dancer ( 8 ). The elastic rod ( 86 ) is pressurized to uphold against the fixation bit ( 25 ) on the carrier track ( 2 ).  
         [0028]     Furthermore, as illustrated in  FIGS. 9 and 11 , the rear of the carrier track ( 2 ) is properly shortened; or alternatively, the location of the dancer ( 8 ) is moved backward so that the retaining bit ( 84 ) of the dancer ( 8 ) directly extends out of the rear end of the carrier track ( 2 ) to reach the inner side of the fixed track ( 3 ) for operation in relation to the compression bit ( 32 ). In the configuration, the design of the notch ( 23 ) is not required since the rear end of the carrier track ( 2 ) is cut off at where the notch ( 23 ) is otherwise provided, and the location of the stopper ( 21 ) is properly changed.