Patent Publication Number: US-7708359-B2

Title: Latch mechanism for slide rail assembly

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a latch mechanism for a slide rail assembly. 
   2. Description of Related Art 
   Slide rails are used in a variety of applications, including business furniture, kitchen drawers, electronic racks, and copiers. One type of slide rail is a telescopic slide rail. Telescopic slide rails often comprise two, three, four or more telescoping members. The shape of a slide rail, and the individual members, are determined by the design. The slides can be frictional, with lubricated members rubbing against each other, or a slide assembly may include roller or ball bearings for easier movement. The members in such assemblies tend to be C-shaped in nature. 
   A conventional three-section slide rail assembly for a drawer includes a first slide rail (e.g. outer slide rail), a second slide rail (e.g. middle slide rail), and a third slide rail (e.g. inner slide rail). A ball rail is sandwiched between any two of the first slide rail, the second slide rail, and the third slide rail to provide a smooth sliding movement. Moreover, the third slide rail and the second slide rail mount a retaining member and a stop member respectively to prevent the slide rails extending too far. The retaining member is attached to an inner surface of the third slide rail, and provided with an inclined wall. The stop member is mounted to a front end of the second slide rail, and provided with a protrusion. To prevent users from drawing the third slide rail out too far from the second slide rail, the protrusion of the stop member engages with the inclined wall of the retaining member. 
   Users can draw out a keyboard or a component, which is attached to the third slide rail, for servicing. Although the engagement of the stop member with the inclined wall avoids the release of the third slide rail from the second slide rail by accident, it cannot prevent the third slide rail retracting into the second slide rail too far by careless force of users. Therefore, it is inconvenient to users for operating the slide rail assembly in use. 
   Consequently, it is required to provide a two-way latch mechanism for a slide rail assembly. 
   SUMMARY OF THE INVENTION 
   In one preferred embodiment, a latch mechanism is provided for retaining a slide rail assembly, which includes first and second slide rails. The latch mechanism includes a latch member movably attached to the second slide rail, a stop member mounted to the first slide rail to engage in the latch member for retaining the second slide rail relative to the first slide rail, and a release member slidably attached to the second slide rail. The latch member includes first and second driven portion at one side thereof, and a cutout. The cutout has a first and second stop surfaces at opposite ends thereof. The release member is capable of pushing the first or second driven portion to release the first or second stop surface from the stop member. A resilient member is placed between the latch member and the second slide rail for returning the latch member to an original position. 
   Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an assembled view of a slide rail assembly according to a preferred embodiment of the present invention; 
       FIG. 2  is an exploded, isometric view of  FIG. 1 ; 
       FIG. 3  is an enlarged view of a latch member of the slide rail assembly of  FIG. 2 ; 
       FIG. 4  is an inverted view of part of  FIG. 2 ; 
       FIG. 5  is an assembled view of  FIG. 4 ; 
       FIG. 6  is an enlarged view of a circled portion VI of  FIG. 5 ; and 
       FIGS. 7-9  are lateral views of the slide rail assembly of  FIG. 1  in three using states. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 1 and 2 , in a preferred embodiment of the invention, a latch mechanism is provided for retaining a slide rail assembly which includes a first slide rail  10 , and a second slide rail  20 . The latch mechanism includes a latch member  30 , a release member  40 , a resilient member  50 , a stop member  60  mounted on the first slide rail  10 , a mounting member  80 , and two posts  90 . 
   Referring to  FIGS. 3 and 4 , the second slide rail  20  defines two mounting holes  21  therein at a predetermined retaining position of the second slide rail  20  and the first slide rail  10 . A bent tab  22  is formed on the second slide rail  20  between the two mounting holes  21 . Two through holes  24  are defined in the second slide rail  20  in the vicinity of the mounting holes  21 . 
   The latch member  30  has two opposite sides, wherein one side comprises two stepped portions  312 , and a space  31  between the stepped portions  312 , and wherein the other side is stepped and comprises two inclined portions  34  at opposite ends thereof, a cutout  32  between the two inclined portions  34 , and a recess portion  36  that is generally V-shaped and has a first driven portion  362  and a second driven portion  364 . The cutout  32  has a first and a second stop surface  322 ,  324  formed from two sidewalls thereof respectively. Two arc-shaped slots  38  are defined in opposite ends of the latch member  30 . 
   The release member  40  is elongated, and includes an operating portion  42  arranged at one end thereof, a cam  44  formed from an opposite end thereof, and a plurality of tabs  46  extending from a middle portion thereof. The cam  44  is V-shaped, and forms a first driving portion  442  and a second driving portion  444  at two sides thereof respectively. 
   The resilient member  50  is generally V-shaped, and preferably made by bending a resilient steel wire. The stop member  60  includes a protrusion  62  bent from a side thereof. 
   The mounting member  80  is generally rectangular and includes a stepped side surface. Two mounting holes  82  are defined in the mounting member  80 . 
   Referring also to  FIGS. 5 and 6 , in assembly, the release member  40  is attached to the second slide rail  20 . The mounting member  80  is mounted on the second slide rail  20  by two screws  84  extending through the mounting holes  82  of the mounting member  80  to engage in the through holes  24  of the second slide rail  20  respectively. The tabs  46  of the release member  40  are located under the mounting member  80 . The latch member  30  is attached to the second slide rail  20 . The cam  44  of the release member  40  is received in the recess portion  36  of the latch member  30 . A middle portion of the resilient member  50  is held under the bent tab  22  of the second slide rail  20 , and two distal ends of the resilient member  50  engage with the stepped portions  312  of the latch member  30  respectively. Two posts  90  extend through the slots  38  of the latch member  30  to be screwed into the mounting holes  21  of the second slide rail  20  respectively, thus the latch member  30  is movably mounted to the second slide rail  20 . The stop member  60  is mounted to one end of the first slide rail  10  opposing the latch member  30 . 
   Referring also to  FIG. 7 , when pushing the second slide rail  20  to slide into the first slide rail  10 , the leading inclined portion  34  of the latch member  30  rides over the protrusion  62  of the stop member  60 , thereby biasing the latch member  30  counter-clockwise against the resilient member  50  until the protrusion  62  of the stop member  60  slides into the cutout  32  of the latch member  30 . 
   Referring also to  FIG. 8 , after the protrusion  62  of the stop member  60  enter into the cutout  32  of the latch member  30 , the resilient member  50  rebounds to return the latch member  30  to its original position, thus the protrusion  62  of the stop member  60  is locked in the cutout  32  of the latch member  30 . Therefore, the protrusion  62  of the stop member  60  is confined by the first stop surface  322  or the second stop surface  324  of the cutout  32  of the latch member  30  to avoid the second slide rail  20  moving outward or inward relative to the first slide rail  10 . 
   Referring also to  FIG. 9 , in releasing the second slide rail  20  from the first slide rail  10 , push the operating portion  42  of the release member  40  inward along the second slide rail  20 . The first driving portion  442  of the cam  44  engages with the first driven portion  362  of the latch member  30  to bias the latch member  30  counter-clockwise. The first stop surface  322  of the latch member  30  disengages from the protrusion  62  of the stop member  60  which allows the second slide rail  20  outward without allowing inward movement relative to the first slide rail  10 . The same principle applies when pushing the release member  40  outward along the second slide rail  20 . The second driving portion  444  of the cam  44  pushes the second driven portion  364  of the latch member  30  to bias the latch member  30  clockwise. The second stop surface  324  of the latch member  30  disengages from the protrusion  62  of the stop member  60  which allows the second slide rail  20  inward without allowing outward movement relative to the first slide rail  10 . 
   When the latch member  30  leaves the protrusion  62  of the stop member  60 , releasing the operating portion  42  of the release member  40 , the resilient member  50  rebounds to return the latch member  30  to its original position. The first driven portion  362  or the second driven portion  364  of the latch member  30  drives the cam  44  of the release member  40  to return the release member  40  to its original position. 
   The protrusion  62  may extend from the first slide rail  10  directly. A spring can be placed between the release member  40  and the second slide rail  20  for returning the release member  40  to its original position. 
   It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.