Retaining structure for a track device

[0001] 1. Field of the Invention

[0002] The present invention relates to a retaining structure for a track device with at least two tracks such that the tracks move in sequence when they are pushed inward or pulled outward.

[0003] 2. Description of the Related Art

[0004] FIG. 11 of the drawings illustrates a so-called three-partconventional 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 a protrusion 951 of the claw 95 to move across a stop piece 971 of 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 protrusion 951 of the claw 95 is engaged with the stop piece 971 of the stop 97 when the inner track 93 is pulled outward, thereby preventing disengagement of the inner track 93 from the middle track 92.

[0005] For a drawer, two inner tracks 93 are respectively mounted to two opposite lateral walls of the drawer and two outer tracks 91 are respectively mounted to two inner lateral walls of a furniture piece (such as a desk) that receives the drawer. It was, however, found that sometimes the tracks 92 or 93 cannot move synchronously while pushing the drawer inward. Movement of the drawer is thus unbalanced and not smooth, and sometimes even stuck.

[0006] It is the primary object of the present invention to provide a retaining structure for a track device, wherein the retaining structure retains the track device in place when the track device is unintentionally impinged, thereby preventing undesired inward movement of the track device.

[0007] It is another object of the present invention to provide a retaining structure for a three-part track device, wherein the second track firstly slides outward relative to the first track when the track device is extended from its fully collapsed state. When the second track reaches a predetermined position, the third track is allowed to slide relative to the second track. When collapsing the track device from its fully extended state, the third track is firstly retracted inward relative to the second track. When the third track reaches a predetermined position, the second track is allowed to retract into the first track.

[0008] In accordance with a preferred embodiment of the invention, a track device comprises a first track, a second track slidably received in the first track, and a third track slidably received in the second track. The first track includes a retaining block having an upper side and an underside side. Each of the upper side and the underside side of the retaining block has a first end having an inclined surface tapering toward a longitudinal axis of the retaining block. Each of the upper side and the underside side of the retaining block further has a second end with an engaging portion. The second track is slidably received in the first track and has a clamping member mounted thereto. The clamping member includes a main body with two opposite sides and two resilient legs each having an intermediate portion connected to an associated side of the main body. Each resilient leg further includes a first end extending beyond the main body and a second end extending beyond the main body. A distance between the first ends of the resilient legs is smaller than that between the second ends of the resilient legs. The first ends of the resilient legs are releasably engaged with the retaining block and releasably retained on the engaging portions of the retaining block.

[0009] Other objects, specific advantages, and novel features of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings.

[0010] FIG. 1 is an exploded perspective view of a track device in accordance with the present invention.

[0011] FIG. 2 is a partial exploded perspective view of a first track and a second track of the track device in accordance with the present invention.

[0012] FIG. 3 is a side elevational view of the track device in accordance with the present invention in a collapsed state.

[0013] FIG. 4 is a sectional view taken along line 4-4 in FIG. 3.

[0014] FIG. 5 is a view similar to FIG. 3, wherein the inner track is pulled outward.

[0015] FIG. 6 is a sectional view taken along line 6-6 in FIG. 5.

[0016] FIG. 7 is a view similar to FIG. 5, wherein the track device is in its fully extended state.

[0017] FIG. 8 is a sectional view taken along line 8-8 in FIG. 7.

[0018] FIG. 9 is a sectional view taken along line 9-9 in FIG. 8.

[0019] FIG. 10a is a perspective view of a first embodiment of an engaging member in accordance with the present invention.

[0020] FIG. 10b is a perspective view of a second embodiment of the engaging member in accordance with the present invention.

[0021] FIG. 10c is a perspective view of a third embodiment of the engaging member in accordance with the present invention.

[0022] FIG. 11 is an exploded perspective view of a conventional track device for a drawer.

[0023] Preferred embodiments in accordance with the present invention will now be described with reference to the accompanying drawings.

[0024] Referring to FIG. 1, a three-part 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 includes holes 11 so as to be fixed to an inner lateral wall of a furniture piece (not shown). The first track 1 includes an upper longitudinal lip 12 and a lower longitudinal lip 12 for guiding sliding movement of the second track 2 in the first track 1. Slide-aiding members 13 are provided between the first track 1 and the second track 2. A stop 14 is formed on an end of the first track 1 and a stop 21 is formed on an end of the second track 2 to prevent disengagement of the second track 2 from the first track 1 after the second track 2 is mounted into the first track 1. A stop 15 is mounted to the other end of the first track 1 for preventing disengagement of the second track 2 via the other end of the first track 1. The first track 1 further includes a guide block 16 for providing stable movement of the second track 2.

[0025] The second track 2 is mounted into the first track 1 and slidable between the upper lip 12 and the lower lip 12 of the first track 1. The second track 2 includes an upper longitudinal lip 22 and a lower longitudinal lip 22 for guiding sliding movement of the third track 3 in the second track 2. A slide-aiding member 23 is provided between the second track 2 and the third track 3. In a preferred embodiment of the invention, the slide-aiding member 23 includes two lateral extensions (not labeled) respectively facing the upper and lower longitudinal lips 22 and having a plurality of balls 24 to provide the best sliding contact between the second track 2 and the third track 3. As mentioned above, the stop 24 on the second track 2 prevents disengagement of the second track 2 from the first track 1. In addition, a stop 25 with a stop piece 251 is provided on the other end of the second track 2 for engaging with a protrusion 312 of a claw 31 on the third track 3, thereby preventing disengagement of the third track 3 from the second track 2.

[0026] The third track 3 is mounted in the second track 2 and slidably guided between the upper and lower longitudinal lips 22 of the second track 2. The third track 3 includes holes (not labeled) so as to be nailed to an outer lateral wall (not shown) of a drawer (not shown) that is received in the furniture piece. The claw 31 of the third track 3 includes a resilient leg 311. The resilient leg 311 can be pressed to allow the protrusion 312 of the claw 31 to move across the stop piece 251 of the stop 25, thereby allowing assembly or detachment between the third track 3 and the second track 2. After the third track 3 has been engaged in the second track 2, the protrusion 312 of the claw 31 is engaged with the stop piece 251 of the stop 25 when the third track 3 is pulled outward, thereby preventing disengagement of the third track 3 from the second track 2.

[0027] Referring to FIGS. 1 and 2, the present invention is characterized in that the first track 1 includes a retaining block 17 and the second track 2 includes a clamping member 26. The retaining block 17 is fixed to the first track 1 at an appropriate place and is formed to have a structure shown in either one of FIGS. 10a through 10c. More specifically, as illustrated in FIGS. 10a, 10b, and 10c, the retaining block 17 includes an upper side and an underside each having a first end with an inclined surface 171 tapering toward a longitudinal axis of the retaining block 17, a second end with a recessed engaging portion 173, and an intermediate portion 172 between the first end and the second end. The retaining block 17 has a maximum width defined between the intermediate portions 172 of the upper side and underside thereof.

[0028] As illustrated in FIG. 2, the clamping member 26 is fixed to an end of the second track 2 that is away from the retaining block 17 of the first track 1 when the track device is in its fully collapsed state, as shown in FIG. 3. The clamping member 26 includes a main body (not labeled) and two resilient legs 27 respectively provided on upper and lower sides of the main body. Each resilient leg 27 includes a first end 271, an intermediate portion connected with the main body, and a second end 272. First ends 271 and second ends 272 of the resilient legs 27 extend beyond the main body. A distance S between the first ends 271 of the resilient legs 27 is smaller than a distance L between the second ends 272 of the resilient legs 27. The first ends 271 of the resilient legs 27 can be engaged with the recessed engaging portions 173 of the retaining block 17, thereby providing a retaining function. In addition, the second ends 272 of the resilient legs 27 can press against upper and lower inner wall surfaces of the third track 3, respectively, thereby providing a frictional force between the second track 2 and the third track 3 such that the third track 3 and the second track 2 move together.

[0029] Referring to FIGS. 3 and 4, the three-part track device in accordance with the present invention is in its fully collapsed state in which the retaining block 17 and the clamping member 26 are far away from each other. Thus, the resilient legs 27 of the clamping member 26 retain its original shapes with the second ends 272 of the resilient legs 27 pressing against upper and lower inner wall surfaces of the third track 3, respectively.

[0030] Referring to FIGS. 5 and 6, when the track device is pulled outward, since the second ends 272 of the resilient legs 27 are frictionally engaged with upper and lower inner wall surfaces of the third track 3, respectively, the second track 2 and the third track 3 move together relative to the first track 1 until the first ends 271 of the resilient legs 27 engage with the inclined portions 171 of the retaining block 17. The first ends 271 of the resilient legs 27 then move to the intermediate portions 172. The second ends 272 of the resilient legs 27 are moved toward each other and thus disengaged from upper and lower inner wall surfaces of the third track 3. As a result, the second track 2 separates from the third track 3 to allow sliding movement of the latter relative to the former.

[0031] Referring to FIGS. 7 and 8, when the third track 3 moves to an outermost position relative to the second track 2, the first ends 271 of the resilient legs 27 are engaged with the recessed engaging portions 173 of the retaining block 17, as illustrated in FIG. 9. The track device is in its fully extended state.

[0032] Since the first ends 271 of the resilient legs 27 are engaged with the recessed engaging portions 173 of the retaining block 17 when the track device is in its fully extended state, the drawer will not be moved inward if it is unintentionally impinged. In addition, the engaging force between the first ends 271 of the resilient legs 27 and the recessed engaging portions 173 of the retaining block 17 is greater than the frictional force provided by the second ends 272 of the resilient leg 27 to the third track 3. Thus, when the track device is to be retracted from its fully extended state, the third track 3 will firstly be retracted into the second track 2 until the retracting force from the second track 2 overcomes the engaging force between the first ends 271 of the resilient legs 27 and the recessed engaging portions 173 of the retaining block 17. At this time, the first ends 271 of the resilient legs 27 move across the intermediate portions 172 and the inclined surfaces 171, thereby allowing the second track 2 to slide relative to the first track 1 while the second ends 272 of the resilient legs 27 pressing against upper and lower inner wall surfaces of the third track 3, respectively.

[0033] In use, two track devices in accordance with the present inventions are mounted to two opposite lateral walls of a drawer and two inner lateral walls of a furniture piece that receives the drawer. By means of provision of the retaining structure in accordance with the present invention, the first ends 271 of resilient legs 27 retain the track device in place when the track device is unintentionally impinged, thereby preventing undesired inward movement of the drawer. In addition, the sliding movements of the track device are more smooth without the risk of sticking of the drawer, as the track devices on both sides of the drawer operate synchronously. The retaining structure in accordance with the present invention can be applied to a two-part track device using only two tracks.

[0034] 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.