Abstract:
A pressure release slide latch mechanism for a drawer slide assembly comprises an outer slide, an intermediate slide mounted in the outer slide, and an inner slide mounted in the intermediate slide, a channel plate having a track portion and a guide block attached to the outer slide and a carriage slidingly engaged and biased along the track portion. A pin of a follower pivotally attached to the inner slide engages the guide block to releasably maintain the drawer slide assembly in a closed position and releases upon an inward force applied to the drawer slide assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation-In-Part of application Ser. No. 14/281,643, filed May 19, 2014, which is a Continuation-In-Part of application Ser. No. 13/460,197, filed Apr. 30, 2012, now abandoned. Each patent application identified above is incorporated here by reference in its entirety to provide continuity of disclosure. 
    
    
     FIELD OF THE DISCLOSURE 
     The present invention relates to slide assemblies for mounting drawers in cabinetry. In particular, the invention relates to extension ball bearing slide assemblies with a durable pressure release slide latch mechanism which retains the slide assembly in a closed position and opens upon exerting an inward force to release and open the slide assembly. 
     BACKGROUND OF THE DISCLOSURE 
     Drawer slide assemblies mounted to cabinets and drawers for slidably opening and closing a drawer are well known in the art. The assemblies typically include at least two slide rails that are telescopically mounted within one another to extend and retract. The typical assembly includes an outside rail, which is mounted to the cabinet and an inside rail, which is mounted to the drawer. Ball bearing assemblies are usually mounted between the rails to reduce the friction between the rails. This reduction in friction between the rails allows the drawer to easily open and close. As a result, the drawer can unintentionally open causing injury and/or causing the contents of the drawer to escape. For example, a child can easily pull open a drawer and strike a body part against the open drawer causing injury. In another example, a drawer mounted to a cabinet installed in a recreational vehicle can unintentionally open during movement causing the contents of the drawer to dislodge and escape. 
     The prior art has attempted to solve these problems. For example, U.S. Pat. No. 7,083,243 to Lee discloses a self-closing and opening-preventing device for slide rails. The device includes a housing mounted to the inside of a fixing rail attached to a cabinet. The housing has a central long pin guiding groove to accept a pin attached to a moveable rail. A cam slider moves within the housing and a spring is attached to the rear of the housing and to the cam slider. Engaging jaws mounted on the cam slider can be locked in the engaging holes. The engaging jaws are configured to receive an actuating pin fixed to a moveable rail to lock the opening-preventing device. 
     However, the device requires numerous parts that easily wear leading to failure of the device. Specifically, the spring remains in a stretched position until the engaging jaws engage the actuating pin. This constant tension leads to fatigue and premature failure. Further, the pins of the cam slider on which the engaging jaws are mounted are thin which leads to the severance of the pins from the cam slider. 
     U.S. Pat. No. 7,104,691 to Chi discloses a self-moving mechanism to keep a drawer slide in a closed position. The mechanism includes a housing mounted to a first slide rail, an actuator wader spring compression moveable within the housing wherein the movement of the actuator is guided by a series of slots, and an angled slit formed in the web of a second slide rail telescopically mounted to the first slide. As the second slide retracts, the angled slit engages a pin attached to the actuator and the actuator urges the pin and the second slide into a retracted position. Flexible tines adjacent a longitudinal slot keeps the pin of the actuator, and thereby the second slide, in a retracted position. The mechanism disclosed in Chi requires thin tines cut into a wall in the housing to keep the second slide in a retracted position, which leads to fatigue and ultimately failure. The premature failure renders the entire mechanism useless. Further, Chi does not provide a push to open feature. 
     U.S. Pat. No. 7,854,485 to Berger discloses a closing and opening device for drawers. A latch housing is attached to an outer rail and a moveable catch component slidably moves within the latch housing. The moveable catch component is moved by a dog attached to a running rail slidingly engaged with the outer rail and attached to a drawer. The moveable catch component is biased by a coupling rod adjacent to the moveable catch component and under spring compression. The coupling rod has a ball head to frictionally engage a receiver of the moveable catch component. Opposite the moveable catch component is a lever hingedly connected to the coupling rod. The lever has a projection that guides the lever along a cam path. 
     However, the device in Berger requires the ball head to frictionally engage the receiver of the moveable catch component each and every time the drawer is closed. Once the projection and lever is released from the closed position the ball head remains frictionally engaged with the moveable catch component requiring further pulling force to release the drawer. This constant frictional engagement between the ball head and the receiver leads to premature wear and ultimately failure, which results in rendering the opening and closing device useless. 
     The prior art fails to disclose or suggest a pressure release slide latch mechanism with a push to open feature that will not result in premature failure. Therefore, there is a need for a pressure release slide latch mechanism of durable construction allowing for a reliable and easy push to open feature with fewer parts. Anticipated applications of the invention include, but are not limited to environments where no drawer knobs or pull handles are desired, environments where safety is a concern such, and/or environments where sanitary conditions are a concern. For example, hospitals may use the invention to reduce the collection of bacteria on handles or knobs and daycare centers where the invention may be used reduce injury from striking protruding hardware and from the unintentional opening of a drawer. 
     SUMMARY OF THE DISCLOSURE 
     In a preferred embodiment, a pressure release slide latch mechanism for a drawer slide assembly comprises an outer slide member, an intermediate slide member telescopically mounted to the outer slide member, and an inner slide member telescopically mounted to the intermediate slide member. The preferred embodiment further comprises a channel plate having a track portion and a guide block attached to the outer slide member and a carriage slidingly engaged with the track portion of the channel plate. Two tension springs are attached to an end of the track portion and the carriage to bias the carriage. The guide block has a plurality of channels and a latch member to receive a pin of a follower pivotally attached to the inner slide member to releasably maintain the inner slide member and the intermediate slide member in a locked position with respect to the outer slide member. The pivotal movement of the follower is limited by a guide post connected to the follower and the engagement of the guide post with the inner slide member. 
     In use, to close the drawer slide assembly using the pressure release slide latch mechanism the intermediate slide member and the inner slide member approach a retracted position with respect to the outer slide member, the intermediate slide member engages the carriage and urges the carriage against the tension of the springs. Simultaneously, the inner slide member engages a set of bumpers on the carriage while the pin of the follower slidingly engages a ramp of the guide block and redirecting surfaces to guide the pin through an inlet channel and into a first positioning recess. Under spring bias from the springs attached to the channel plate and the carriage, the carriage extends the intermediate slide member and the inner slide member causing the pin to abut the latch member to retain the inner slide member and the intermediate slide member in a locked position with respect to the outer slide member. 
     To release the inner slide member and the intermediate slide member from the outer slide member, the inner slide member is urged against the tension of the springs to release the pin from the latch member and the pin is positioned by a redirecting surface into a second positioning recess. Under spring tension, the pin is allowed to travel through an outlet channel and engages redirecting surfaces to direct the pin out of the ramp to release the pin and thereby release the inner slide member and the intermediate slide member allowing the inner slide member and the intermediate slide member to telescopically extend with respect to the outer slide member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosed embodiments will be described with reference to the accompanying drawings. Like pieces in different drawings carry the same number. 
         FIG. 1A  is an exploded isometric view of a preferred embodiment. 
         FIG. 1B  is a detail view of a pressure release slide latch mechanism of a preferred embodiment. 
         FIG. 2  is an assembled side view of a preferred embodiment. 
         FIG. 3  is a partial section view of a guide block of a preferred embodiment taken along line I-I of  FIG. 2 . 
         FIG. 4  is a partial section view of a guide block engaged with a follower of a preferred embodiment taken along line I-I of  FIG. 2 . 
         FIG. 5A  is a side view of a follower approaching a guide block of a preferred embodiment. 
         FIG. 5B  is a side view of a follower approaching a guide block of a preferred embodiment. 
         FIG. 5C  is a side view of a follower after entering a guide block of a preferred embodiment. 
         FIG. 6  is a side view of a follower engaged with an inlet channel of a guide block of a preferred embodiment. 
         FIG. 7  is a side view of a follower engaged with a positioning recess of a guide block of a preferred embodiment. 
         FIG. 8  is a side view of a follower engaged with a catch surface of a guide block of a preferred embodiment. 
         FIG. 9  is a side view of a follower engaged with a redirecting surface of a guide block of a preferred embodiment. 
         FIG. 10  is a side view of a follower engaged with a positioning recess of a guide block of a preferred embodiment. 
         FIG. 11  is a side view of a follower engaged with a redirecting surface of a guide block of a preferred embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1A , drawer slide assembly  10  comprises outer slide member  100 , intermediate slide member  200  telescopically mounted to outer slide member  100 , and inner slide member  300  telescopically mounted to intermediate slide member  200 . Outer slide member  100  has outer body portion  101  and opposing races  102  and  103  attached to outer body portion  101 . Outer body portion  101  has catches  104 ,  105 , and  106 , and slots  107  and  108 . 
     In a preferred embodiment, outer slide member  100  is made of a durable metal or metal alloy. Other durable materials known in the art may be used. Catches  104 ,  105 , and  106  are raised portions of outer body portion  101  stamped into outer body portion  101  having a generally hooked shape. Slots  107  and  108  are generally rectangular holes cut out of outer body portion  101 . Other shapes and structures known in the art may be employed to provide a fastening means. 
     Cage  109  telescopically slides into race  102 . Cage  109  includes a plurality of ball bearings  111  inserted into holes in cage  109  and positioned along an inside surface of race  102 . Cage  110  telescopically slides into race  103 . Cage  110  includes a plurality of ball bearings  112  inserted into holes in cage  110  and positioned along an inside surface of race  103 . 
     In a preferred embodiment, cages  109 ,  110 , and ball bearings  111  and  112  are made of a durable metal or metal alloy. Other durable materials known in the art may be used. 
     Intermediate slide member  200  telescopically mounts to outer slide member  100  with cages  109  and  110  positioned between intermediate slide member  200  and outer slide member  100 . An outside surface of race  202  is adjacent ball bearings  111  of cage  109 . An outside surface of race  203  is adjacent ball bearings  112  of cage  110 . Intermediate slide member  200  has intermediate body portion  201  and opposing races  202  and  203  attached to intermediate body portion  201 , end  215 , and end  216 . Intermediate body portion  201  has ridge  204  formed into intermediate body portion  201  and extends longitudinally and generally centrally along intermediate body portion  201 . 
     In a preferred embodiment, intermediate slide member  200  is made of a durable metal or metal alloy. Other durable materials known in the art may be used. Ridge  204  is a stamped portion of intermediate body portion  201 . Other structures known in the art may be employed to form ridge  204 . 
     Intermediate stop  205  attaches to intermediate slide member  200  at end  215 . Intermediate stop  205  has stop ridge  206  and stop catch  207 . Intermediate stop  205  has a cross-sectional shape similar to that of intermediate slide member  200  enabling intermediate stop  205  to press-fit into intermediate slide member  200  at end  215  and conform to the cross-sectional shape of intermediate slide member  200 . Other means of attachment known in the art may be employed. 
     In a preferred embodiment, intermediate stop  205  is made of a single piece of durable plastic. Other durable materials known in the art may be used. 
     Bearing retainer  208  telescopically inserts into intermediate slide member  200 . Bearing retainer  208  has retainer body portion  209  and opposing cages  211  and  212  attached to retainer body portion  209 . Retainer body portion  209  has retainer ridge  210  formed into retainer body portion  209  and extends longitudinally and generally centrally along retainer body portion  209 . Cage  211  has a plurality of ball bearings  213  inserted into holes in cage  211 . Cage  212  has a plurality of ball bearings  214  inserted into holes in cage  212 . 
     In a preferred embodiment, bearing retainer  208 , cages  211 ,  212 , and ball bearings  213  and  214  are made of a durable metal or metal alloy. Other durable materials known in the art may be used. In this embodiment, retainer ridge  210  is a stamped portion of retainer body portion  209 . Other structures known in the art may be employed to form retainer ridge  210 . 
     Inner slide member  300  telescopically mounts to intermediate slide member  200  with bearing retainer  208  positioned between inner slide member  300  and intermediate slide member  200 . Inner slide member  300  has inner body portion  301 , opposing races  302  and  303 , end  322 , and end  323 . End stop  304  is attached to inner body portion  301  at end  322 . Inner body portion  301  has recesses  305  and  306  at end  323 . Inner body portion  301  further has hole  310  through which fastener  327  is received, hole  319  through which fastener  324  is received, and guide slot  320 . Race  302  has race slot  307  at end  323 . Race  303  has race slot  308  at end  323 . 
     In a preferred embodiment, inner slide member  300  is made of a durable metal or metal alloy. Other durable materials known in the art may be used. In this embodiment, guide slot  320  is generally rectangular in shape. In another embodiment, guide slot  320  is generally arcuate in shape. Other shapes will suffice. 
     Follower  315  pivotally connects to inner slide member  300  with fastener  324  inserted through hole  319 . Follower  315  includes follower body  316 . Follower body  316  has end  325 , end  326 , and pivot hole  317  at end  326  through which fastener  324  is inserted. Guide post  318  attaches to follower body  316  between end  325  and end  326  and extends generally perpendicularly from follower body  316  into guide slot  320  of inner body portion  301 . Pin  321  attaches to follower body  316  at end  325  and extends generally perpendicularly from follower body  316  away from inner body portion  301 . 
     In a preferred embodiment, follower  315  is formed of a single piece of plastic such as Delrin® and Teflon®. Other durable materials, including other plastics, metals and metal alloys, may be used. In this embodiment, fastener  324 , is a flush rivet. Other suitable fasteners known in the art may be employed. 
     Latch  309  pivotally connects to inner body portion  301  with fastener  327  through hole  310 . Latch  309  has latch handle  311 , resilient member  312 , shoulder  314 , and hole  313 , sized to receive fastener  327 . Resilient member  312  urges shoulder  314  towards race  302 . Shoulder  314  engages stop catch  207  of intermediate stop  205  to prevent disengagement of inner slide member  300  from intermediate slide member  200 . 
     In a preferred embodiment, latch  309  is formed of a single piece of plastic such as Delrin® and Teflon®. Other durable materials, including other plastics, metals and metal alloys, may be used. In this embodiment, fastener  327 , is a flush rivet. Other suitable fasteners known in the art may be employed. 
     Referring to  FIG. 1B , channel plate  400  attaches to outer slide member  100 . Channel plate  400  has track portion  401  and guide block  402 . Guide block  402  is adjacent to track portion  401  and end  434 . Track portion  401  has catch surfaces  431 ,  432 , and  433  that frictionally engage with catches  104 ,  105 , and  106  of outer body portion  101 . Carriage track  407  is adjacent catch surface  433  and extends generally centrally and longitudinally along track portion  401 . Spring guides  403  and  404  are each positioned on each side of carriage track  407  immediately adjacent to catch surface  433  at end  435 , extend beside carriage track  407  increasing in distance from a central axis of carriage track  407 , and extend between guide block  402  and outer body portion  101  to a distance approximately greater than the width of guide block  402  at end  434 . Spring guide  403  has spring hold  405  adjacent catch surface  433  to secure spring  421 . Spring guide  404  has spring hold  406  adjacent catch surface  433  to secure spring  422 . 
     Carriage  420  slidingly engages with track portion  401 . Carriage  420  has frame  423 , extension  425 , and extension  426 . Frame  423  has rail  424  extending generally centrally and longitudinally along frame  423  to slidingly engage with carriage track  407 . Extension  425  has bumper  427  to which spring  421  is further attached. Extension  426  has bumper  428  to which spring  422  is further attached. The attachment of springs  421  and  422  to track portion  401  and carriage  420  biases carriage  420  along track portion  401  towards end  435 . 
     Guide block  402  has ramp  430 , inlet shoulder  412 , inlet channel  409 , positioning recess  411 , latch member  429 , redirecting surface  413 , positioning recess  410 , outlet channel  408 , and outlet shoulder  414 . Lugs  415  and  416  extend from end  434  adjacent guide block  402 . Lugs  415  and  416  frictionally engage with slots  418  and  419 , respectively, of base  417 . Base  417  frictionally engages with the ends of races  102  and  103  of outer slide member  100  to further secure channel plate  400  to outer slide member  100 . 
     In a preferred embodiment, channel plate  400 , carriage  420 , and base  417  are made of plastic. Other durable materials, including metals and metal alloys, may be used. In this embodiment, springs  421  and  422  are coil tension springs. Other resilient materials known in the art including, but not limited to elastic rubber bands may be employed. Other resilient biasing means known in the art may be employed including, but not limited to compression springs, elastomeric materials such as neoprene, fluid-filled piston/cylinder arrangements, and combinations thereof positioned in spring guide  403  and/or spring guide  404  at end  434  to urge carriage  420  towards end  435  will suffice. 
     Referring to  FIG. 2 , cage  109  inserts into race  102  of outer slide member  100  and ball bearings  111  are positioned in race  102  to roll within race  102  and along the outside surface of race  202  of intermediate slide member  200 . Cage  110  inserts into race  103  of outer slide member  100  and ball bearings  112  are positioned in race  103  to roll within race  103  and along the outside surface of race  203  of intermediate slide member  200 . 
     Bearing retainer  208  inserts into intermediate slide member  200  such that ball bearings  213  position between inside surface of race  202  and the outside surface of race  302  of inner slide member  300 , and ball bearings  214  position between inside surface of race  203  and the outside surface of race  303  of inner slide member  300 . 
     Ramp  430  has a generally trapezoidal shape with width  503  and width  504 . Width  503  is greater than width  504 . Inlet shoulder  412  includes redirecting surface  442  and peak  443 . Outlet shoulder  414  includes redirecting surface  444 , peak  445 , and redirecting surface  446 . Peaks  443  and  445  are offset such that peak  443  is closer to end  434  than peak  445 . Peak  445  coincides with an edge of ramp  430 . Latch member  429  includes peak  447  and redirecting surface  436 . 
     Follower  315  pivotally attaches to inner slide member  300  with fastener  324 . Follower  315  pivots about the central axis of fastener  324 . The connection of follower  315  to inner slide member  300  is such that frictional forces keep the position of follower  315  relative to inner slide member  300  static and prevent follower  315  from freely rotating unless acted upon by a redirecting surface. The pivotal range of movement of follower  315  is limited by the sliding engagement of guide post  318  with guide slot  320 . As follower  315  pivots, guide slot  320  has dimensions which restrict pin  321  to swing through arcuate path  505 . Arcuate path  505  is less than width  503  to consistently direct pin  321  into guide block  402  via ramp  430  regardless of the position of follower  315 . 
     Referring to  FIGS. 3 and 4 , ramp  430  is angled with respect to outer body portion  101  and inner body portion  301  to consistently direct pin  321  into guide block  402 . Ramp  430  is angled to provide consistent operation during possible deflection of drawer slide assembly  10 . In normal operation, follower  315  is adjacent to and generally parallel with inner body portion  301 . As shown in  FIG. 3 , in a case in which follower  315  separates from inner slide  300 , but remains loosely fastened to inner slide member  300 , pin  321  will slidingly engage ramp  430 . As shown in  FIG. 4 , ramp  430  forces follower  315  back adjacent to and generally parallel with inner slide member  301  thereby correctly positioning pin  321  between redirecting surfaces  442  and  446  and prevents jamming. 
     Referring to  FIGS. 5A-5C , to close drawer slide assembly  10 , inner slide member  300  and intermediate slide member  200  move in proximal direction  501 . Intermediate slide member  200  abuts carriage  420 . Inner slide member  300  engages bumpers  427  and  428  and urges carriage  420  in proximal direction  501  against the bias of springs  421  and  422 . Pin  321  may potentially be positioned anywhere along arcuate path  505 . As pin  321  slidingly engages ramp  430 , either redirecting surface  442  or redirecting surface  446  will cause follower  315  to pivot about the central axis of fastener  324  and position pin  321  towards engagement with redirecting surface  436 . 
       FIG. 5A  shows pin  321  contacting redirecting surface  442  resulting in follower  315  pivoting in direction  506 . 
       FIG. 5B  shows pin  321  contacting redirecting surface  446  resulting in follower  315  pivoting in direction  508 . As pin  321  is positioned to engage redirecting surface  436 , guide post  318  is located generally centrally in guide slot  320 . As inner slide member  300  and intermediate slide member  200  continue to move in proximal direction  501 , pin  321  engages redirecting surface  436  and redirects pin  321  into inlet channel  409 . 
       FIG. 5C  shows pin  321  cresting peak  445  after engaging redirecting surface  436 . As follower  315  continues to move in proximal direction  501 , linear path  449  tracks the center point of pin  321 . The dimensions of outlet shoulder  414 , including peak  445 , and pin  321  ensure that as pin  321  passes peak  445 , linear path  449  is always positioned above (as relationally laid out on the page shown in  FIG. 5C ) peak  447  such that pin  321  is always directed towards contact with redirecting surface  436  when follower  315  is moving in proximal direction  501 . 
     Referring to  FIG. 6 , as inner slide member  300  and intermediate slide member  200  further urge carriage  420  in proximal direction  501  against the bias of springs  421  and  422 , pin  321  is directed into inlet channel  409  between redirecting surfaces  437  and  438  thereby pivoting follower  315  and moving guide post  318  to a first end of guide slot  320 . 
     Referring to  FIG. 7 , as inner slide member  300  and intermediate slide member  200  further urge carriage  420  in proximal direction  501  against the bias of springs  421  and  422 , pin  321  is redirected into positioning recess  411  by redirecting surface  440 . Follower  315  pivots away from the first end of guide slot  320  towards the center of guide slot  320 . 
     Referring to  FIG. 8 , inner slide member  300  and intermediate slide member  200  are urged in distal direction  502  by the bias of springs  421  and  422  until pin  321  engages latch surface  439 . The bias of intermediate slide member  200 , inner slide member  300 , and thereby pin  321  against latch member  429  by springs  421  and  422 , releasably maintains inner slide member  300  and intermediate slide member  200  in a closed retracted position with respect to outer slide member  100 . 
     Referring to  FIG. 9 , to release inner slide member  300  and intermediate slide member  200 , inner slide member  300  and intermediate slide member  200  move in proximal direction  501  and urge carriage  420  against the bias of springs  421  and  422  and away from latch member  429 . Pin  321  engages redirecting surface  413  to direct pin  321  towards positioning recess  410 . Follower  315  pivots towards positioning recess  410  and guide post  318  slides towards a second end of guide slot  320 . 
     Referring to  FIG. 10 , inner slide member  300  and intermediate slide member  200  further move in proximal direction  501  and urge carriage  420  against the bias of springs  421  and  422 . Pin  321  situates in positioning recess  410 . Follower  315  pivots towards positioning recess  410  and guide post  318  slides to the second end of guide slot  320 . From positioning recess  410 , pin  321  can now move into outlet channel  408 . 
     Referring to  FIG. 11 , inner slide member  300  and intermediate slide member  200  move under the bias of springs  421  and  422  in distal direction  502 . The frictional forces from the connection of follower  315  to inner slide member  300  hold the position of follower  315  and pin  321  static and prevent follower  315  and pin  321  from moving relative to inner slide member  300 . Pin  321  moves through outlet channel  408  and engages redirecting surface  444 . Redirecting surface  444  directs pin  321  towards ramp  430  to exit guide block  402 . The redirection of pin  321  by redirecting surface  444  pivots follower  315  back to a generally central position thereby releasing inner slide member  300  and intermediate slide  200  allowing inner slide member  300  and intermediate slide  200  to extend with respect to outer slide member  100  and positioning follower  315  for possible future engagement with ramp  430 . 
     It will be appreciated by those skilled in the art that modifications can be made to the embodiments disclosed and remain within the inventive concept. Therefore, this invention is not limited to the specific embodiments disclosed, but is intended to cover changes within the scope and spirit of the claims.