Patent Publication Number: US-6705689-B2

Title: Track device allowing sequential inward movement

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a track device including three tracks that are moved inward in sequence when desired. 
     2. Description of the Related Art 
     FIG. 8 of the drawings illustrates a so-called “three-track” conventional track device for a drawer. The track device includes an outer track  91 , a middle track  92 , and an inner track  93 . A plurality of rolling balls  94  are mounted between the middle track  92  and the inner track  93  to allow easy sliding movement of the inner track  93  in the middle track  92 . In order to allow easy assembly, the inner track  93  has a claw  95  with a resilient leg  96  and the middle track  92  has a stop  97 . The resilient leg  96  can be pressed to allow the claw  95  to move across the stop  97 , thereby allowing assembly or detachment between the inner track  93  and the middle track  92 . After the inner track  93  has been engaged in the middle track  92 , the claw  95  is engaged with the stop  97  when the inner track  93  is pulled outward to a predetermined position, thereby preventing disengagement of the inner track  93  from the middle track  92 . 
     The outer track  91  is attached to a side of, e.g., a cabinet, and the inner track  93  is attached to a lateral side of, e.g., a drawer of the cabinet. Of course, two sets of the track devices are provided to each lateral side of the drawer. However, no means is provided to prevent inadvertent inward movement of the inner track  93  into the middle track  92  when the inner track  93  is inadvertently impinged. The user&#39;s elbow might be injured. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a track device having a first track, a second track, and a third track. When the track device is extended, members provided between the first track and the second track engage with each other such that the third track and the second track are moved inward in sequence for collapsing the track device while inadvertent sudden closing of the track device is avoided. 
     A track device in accordance with the present invention comprises a first track, a second track, and a third track. The first track comprises an upper longitudinal lip and a lower longitudinal lip. The first track further comprises a first stop and an engaging block. The second track is slidably received between the upper longitudinal lip and the lower longitudinal lip of the first track. The second track comprises a second stop for abutting against the first stop of the first track. The second track further includes a third stop with a protrusion. The second track further includes an upper longitudinal lip and a lower longitudinal lip. The second track further includes a first engaging member on an end thereof. The first engaging member includes an extension member, the extension member including an engaging section and a foot. The third track is slidably received between the upper longitudinal lip and the lower longitudinal lip of the second track. The third track includes a second engaging member for abutting against the third stop of the second track. The second engaging member includes an engaging edge and a leg. The leg is pressable to allow disengagement of the engaging edge from the protrusion on the third stop. 
     Other objects, specific advantages, and novel features a track device including three tracks that are moved inward in sequence when desired of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of a track device in accordance with the present invention. 
     FIG. 2 is a sectional view of the track device in accordance with the present invention in a fully collapsed state. 
     FIG. 3 is a sectional view similar to FIG. 2, wherein the track device is pulled to its fully extended state. 
     FIG. 4 is a view illustrating inward movement of a second track into a first track of the track device. 
     FIG. 5 is a sectional view taken along plane  5 — 5  in FIG.  4 . 
     FIG. 6 is a sectional view illustrating pressing of a lip of a third track against a foot of a retaining member. 
     FIG. 7 is a sectional view taken along plane  7 — 7  in FIG.  6 . 
     FIG. 8 is an exploded perspective view of a conventional track device for a drawer. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment in accordance with the present invention will now be described with reference to the accompanying drawings. 
     Referring to FIG. 1, a track device in accordance with the present invention generally includes a first track  1 , a second track  2 , and a third track  3 . The first track  1  comprises holes  11  so as to be fixed by nails to a wall of furniture. The first track  1  further includes an upper longitudinal lip  12 , a lower longitudinal lip  12  for restraining longitudinal movement of the second track  2  in the first track  1 . Slide-aiding members  13  may be mounted between the first track  1  and the second track  2 . The first track  1  further includes a stop  17  for preventing disengagement of the second track  2  from the first track  1 . The first track  1  further includes a fixed block  14  on an end thereof, thereby preventing disengagement of the second track  2  through the end of the first track  1 . Further, the first track  1  includes an engaging block  15  having a stepped retaining portion  16 . 
     The second track  2  is mounted into and movable between upper and lower longitudinal lips  12 . Also, the second track  2  includes upper and lower longitudinal lips  22  between which the third track  3  is slidably mounted. A slide-aiding member  23  is provided between the second track  2  and the third track  3 . In a preferred embodiment, the slide-aiding member  23  is an integral member and includes balls  24  for providing optimal rolling contact between the second track  2  and the third track  3 . 
     The second track  2  includes two stops  21  and  28  respectively on two ends thereof for preventing disengagement of the third track  3  from the second track  2  and for preventing disengagement of the second track  2  from the first track  1 . A slot  27  is defined in an end of the second track  2 . Adjacent to the slot  27  there is provided a first engaging member  25  that is fixed by fasteners (such as rivets  26 ) to the second track  2 . The first engaging member  25  includes an extension member  251  having an engaging section  252  and a foot  253  extending downward. When the second track  2  moves outward relative to the first track  1 , the extension member  251  moves across the engaging block  15  of the first track  1 . When the second track  2  moves inward into the first track  1 , the engaging section  252  abuts against the stepped retaining portion  16  of the engaging block  15 , thereby preventing inward movement of the second track  2 . When the foot  253  of the first engaging member  25  is pressed against by a bottom of the third track  3 , the extension member  251  is lifted for separating the engaging section  252  from the stepped retaining portion  16  of the engaging block  15 . Further, the slot  27  of the second track  2  receives the first engaging member  25  for restraining movement of the first engaging member  25  in the slot  27 . 
     The third track  3  is mounted in the second track  2  and movable between the upper and lower longitudinal lips  22 . The third track  3  includes holes  32  so as to be fixed by nails to a lateral side of a drawer of the furniture. The third track  3  includes a second engaging member  31 . When the third track  3  is engaged in the second track  2 , and when the third track  3  is pulled outward, an engaging edge  312  of the second engaging member  31  abuts against a protrusion  211  of the stop  21  of the second track  2 , thereby preventing disengagement of the third track  3  from the second track  2 . Further, the second engaging member  31  includes a resilient leg  311 . When engagement/disengagement of the third track  3  with/from the second track  2  is required, the resilient leg  311  is pressed to separate the engaging edge  312  of the second engaging member  31  from the protrusion  211  of the stop  21 . Thus, the second engaging member  31  of the third track  3  may move across the stop  21  of the second track  2 . 
     As illustrated in FIGS. 1 and 2, the engaging block  15  having a stepped retaining portion  16  is provided on the first track  1  and the first engaging member  25  is provided on the second track  2 . The stepped retaining portion  16  is fixed in an appropriate position of the first track  1 . In a preferred embodiment, the stepped portion  16  is located approximately a middle portion of the first track  1 . The first engaging member  25  is fixed on an end of the second track  2  that is in first contact with the first track  1  during assembly. The extension member  251  of the first engaging member  25  is slightly deformable to allow the extension member  251  to move across the engaging block  15  of the first track  1  until the engaging section  252  abuts against the stepped retaining portion  16  of the engaging block  15 , and the foot  253  of the first engaging member  25  may be pressed against by the bottom of the third track  3  to lift the extension member  251  of the first engaging member  25 , thereby disengaging the engaging section  252  from the stepped retaining portion  16  of the engaging block  15 . 
     Referring to FIGS. 3 and 4, when extending the track device, the third track  3  is moved away from the second track  2  until the second engaging member  31  abuts against and is thus stopped by the stop  21  on the second track  2 . The second track  2  is moved away from the first track  1 . The extension member  251  of the first engaging member  25  is moved across the engaging block  15 . The second track  2  is stopped when the stop  28  of the second track  2  abuts against the stop  17  on the first track  1 . At this time, the track device is in a fully extended state. 
     Referring to FIGS. 4 and 5, when the track device in the fully extended state is inadvertently impinged, the second track  2  is allowed to move for a relatively short distance relative to the first track  1 , as the engaging section  252  of the first engaging member  25  on the second track  2  abuts against the stepped retaining portion  16  of the engaging block  15  on the first track  1 . Thus, further inward movement of the second track  2  into the first track  1  is not allowed. As a result, the drawer of the furniture would not be closed suddenly. 
     Referring to FIGS. 6 and 7, when closing of the drawer is required, the third track  3  is moved into the second track  2  until the bottom of the third track  3  presses against the foot  253  of the first engaging member  25 , which causes the extension member  251  of the first engaging member  25  to move upward, thereby disengaging the engaging section  252  from the stepped retaining portion  16  of the engaging block  15 . Thus, further inward collapsing operation of the track device is allowed. 
     The track device in accordance with the present invention is attached to each of two lateral sides of a drawer. Extending operation of the track device can be accomplished without difficulty by means of crossing of the engaging block  15  of the firs track  1 . Inward movement as a result of inadvertent impingement is limited by means of provision of the engaging section  252  of the first engaging member  25  on the second track  2  and the stepped retaining portion  16  of the engaging block  15  on the first track  1 . Thus, sudden inward movement of the track device and the resultant injury to the user are avoided. 
     Although the invention has been explained in relation to its preferred embodiment as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the invention. It is, therefore, contemplated that the appended claims will cover such modifications and variations that fall within the true scope of the invention.