Abstract:
A drawer locking device for locking a plurality of drawers has respective blocking devices for blocking movement of the drawers and a connector connecting the blocking devices such that movement of any of the blocking devices caused by opening of the respective drawer causes a corresponding movement of each remaining blocking device to respective positions in which opening of the respective drawers is blocked. A method of assembling the drawer locking device comprises connecting the blocking devices with a furniture item at respective reference positions provided on the furniture item and fixing the connector to the blocking devices when they are connected with the respective reference positions. This provides a drawer locking device in which the blocking devices are fixed to the connector at spaced positions determined by the reference positions. The drawer locking device can then be disconnected from the item of furniture for refitting in an operative position.

Description:
BACKGROUND TO THE INVENTION  
       [0001]     This invention relates to locking mechanisms for furniture items having multiple drawers.  
         [0002]     Locking mechanisms are known which prevent the opening of more than one drawer in a filing cabinet at any one time. This is to prevent the possibility of the cabinet over-balancing and toppling forward. Such mechanisms typically comprise a series of latching devices which are controlled by an actuator upon opening movement of one drawer to block opening movement of the other drawers. There is an increasing need for such locking mechanisms to be fitted to other items of furniture which feature multiple drawers, such as desks or chests of drawers. Difficulties arise when designing such locking mechanisms to operate on drawer systems which cater for different size drawers or which allow for adjustable positioning of their drawers.  
       SUMMARY OF THE INVENTION  
       [0003]     The invention provides a locking mechanism for an item of furniture having two or more drawers and means mounting the drawers for openable and closable movement, in which each drawer has associated with it a latching device co-operable with the furniture item to allow opening movement of the drawer in a first position of the latching device and to prevent said opening movement in a second position of the latching device, there being a connecting member linking together the latching devices of all the drawers such that opening of any one of the drawers causes the latching devices of all the other drawers to move to their second position, whilst closure of said one drawer causes the latching devices of all the other drawers to return to their first position, wherein the latching devices are connectable to said connecting member at positions to be determined by reference to fixed points on the furniture item for the drawer mounting means.  
         [0004]     The invention also includes a method of assembling a drawer locking device for an item of furniture comprising a plurality of drawers, said drawer locking device comprising respective blocking devices for blocking movement of said plurality of drawers and a connector for connecting said blocking devices such that movement of any one of said plurality of blocking devices caused by opening of the respective drawer causes a corresponding movement of each of the remaining said blocking devices to respective positions in which opening of the respective drawers is blocked, said method comprising connecting said blocking devices with said furniture item at respective reference positions provided in said furniture item, fixing said connector to said blocking devices when said blocking devices are connected with said furniture item at said respective reference positions to provide a drawer locking device in which said blocking devices are fixed to said connector at spaced apart positions determined by said reference positions and disconnecting said drawer locking device from said item of furniture for fitting to said item of furniture in an operative position.  
         [0005]     The invention also includes a drawer locking device for an item of furniture having a plurality of drawers, said locking device comprising a plurality of blocking devices each of which, in use, is movable between a first position permitting opening of a respective drawer and a second position in which opening of the respective drawer is blocked, and a connecting member for connecting said blocking devices such that movement of any one of the blocking device causes a similar movement of each other blocking device, said blocking devices each having a first connecting portion for releasable connection with respective reference connections associated with each drawer in said furniture item and a second connecting portion for connection with said connecting member, the arrangement being such that said connecting member can be connected to said second connecting portions of said blocking devices when said blocking devices are connected with said reference connections by said first connecting portions whereby said blocking devices are connected to said connecting member with a spacing substantially determined by said reference connections. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     By way of example, an embodiment of the invention will now be described with reference to the accompanying drawings, in which:  
         [0007]      FIG. 1  is a schematic, part-sectional view of a filing cabinet incorporating a locking mechanism according to the present invention,  
         [0008]      FIG. 2  shows the actuator track of the  FIG. 1  mechanism,  
         [0009]      FIGS. 3   a  and  3   b  shows the design of the latching device of the  FIG. 1  mechanism,  
         [0010]      FIG. 4  shows the design of the pin member of the  FIG. 1  mechanism, and  
         [0011]      FIGS. 5   a  and  5   b  are diagrammatic illustrations showing how the pin members and latching devices co-operate in use. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0012]      FIG. 1  shows a typical filing cabinet  10  with a number of drawers  11   a,    11   b,    11   c,    11   d.  Each of the drawers is arranged for horizontal opening and closing movement relative to the cabinet via a pair of drawer runners  12   a,    12   b,    12   c,    12   d  on either side of the drawer. Drawer runners for this purpose are well known and typically comprise a pair of generally channel-shaped tracks, one of which is connected to the side of the drawer and the other of which is connected to the inside of the cabinet. Rolling elements such as wheels or ball bearings are captured between the tracks to mount the drawer for rolling movement and to provide support for the weight of the drawer when it is open.  
         [0013]     The inside faces of the cabinet and the outside faces of the drawer sides are pre-drilled with a standard pattern of holes for attaching the drawer runners, usually by means of screws. These hole patterns ensure that when the cabinet is assembled, typically by the consumer at home, the runners are set at the correct spacing and alignment for the drawers.  
         [0014]     The cabinet seen in  FIG. 1  features a locking mechanism for the drawers. The locking mechanism is designed to ensure that only one drawer can be opened at any given time. The mechanism comprises a series of latching devices  13   a,    13   b,    13   c,    13   d,  each of which is associated with a respective drawer  11   a,    11   b,    11   c,    11   d,  with the latching devices all being connected together via a connecting member  14 . The connecting member, with all the latching devices attached, is arranged for slidable movement up and down a groove  15  on the inside face of the cabinet  10 .  
         [0015]     The latching devices  13   a,    13   b,    13   c,    13   d  are engagable by pins associated with each respective drawer (only pin  16   c  is seen in  FIG. 1 ). In use, when all the drawers are closed, the pins  16  and their associated latching devices  13  are in non-interfering engagement, i.e. any one of the drawers is free to be opened. As soon as one of the drawers is opened, however, movement of that drawer&#39;s pin causes its associated latching device to move upwardly. This upward movement of the one latching device is translated via the connecting member  14  to the latching devices of all the other drawers. When all these other latching devices move upwardly in this way, they move into an interfering engagement with their respective pins, i.e. in a sense to block opening movement of their associated drawers. The latching devices are all returned to their original non-interfering position when the drawer first opened is subsequently closed. This is explained in more detail with reference to  FIGS. 5   a  and  5   b.    
         [0016]     One of the difficulties when designing locking mechanisms of this nature is to enable them easily to be adapted to be used with different numbers, sizes and configurations of drawer systems, whilst still remaining relatively simple to assemble and reliable in use. To that end, the connecting member  14  here has been designed as an extruded plastics track to which the latching devices  13  can be fitted by hand with a simple snap action. By this means, the particular number and spacing of latching devices on the connecting member can be tailored to any number of different settings, suiting a wide range of different furniture applications.  
         [0017]     As seen in  FIGS. 3   a  and  3   b,  each latching device  13  is provided with a peg  17  on its front face. The peg  17  is designed to be insertable into one of the standard pre-drilled holes in the cabinet  10  for the drawer runners  12 . On its rear face, each latching device  13  has an arrangement of flexibly resilient feet  18  into which the connecting member  14  can be snap-fitted. In practice, all an assembler has to do before fitting the drawers  11  is place a latching device  13  by its peg  17  in each of the pre-drilled holes, line up the connecting member  14  with all of the latching devices and then press the track into engagement with each device. The connecting member  14  will now have all of the latching devices  13   a,    13   b,    13   c,    13   d  fixed to it at exactly the right relative pitching. The connecting member  14 , with the latching devices  13  all attached, is then turned over and put into the groove  15  in the cabinet  10 . When the drawer runners  12  are then fixed to the cabinet  10  in the usual way, the connecting member  14  is captured in the groove  15 . The groove  15  is sized to receive the connecting member  14 , with all the latching devices  13  attached, for free slidable movement up and down, whilst providing constraint against lateral movement (subject to a small amount of “play”).  
         [0018]      FIGS. 2 and 3   a  and  3   b  show in more detail the design of the connecting member  14  and latching device  13 .  
         [0019]     As seen in  FIG. 2 , the connecting member  14  is a generally U-shaped channel section, conveniently formed as a plastics extrusion. The section features a pair of inwardly facing lips  19  on the inside of the “U” and a pair of flanges  20  on the outside of the “U”.  
         [0020]     As seen in  FIGS. 3   a  and  3   b,  the latching device  13 , which is conveniently in the form of a moulded plastics part, is designed with an arrangement of resiliently flexible feet  18  to enable it to be clipped to the connecting member  14  via the flanges  20 . This arrangement includes a boss  21 . The boss  21  has a diameter which is slightly larger than the space between the inwardly facing lips  19  of the connecting member  14 . This means that when the latching device  13  is clipped onto the connecting member  14 , the feet  18  engage the flanges  20 , and the boss  21  engages between the lips  19  with an interference fit. This serves to ensure that the latching device  13  is securely fixed in position on the connecting member  14 . It will be noted that the arrangement allows the latching device  13  to be positioned on the connecting member  14  in any desired location and even, if necessary, disconnected and re-fitted in a different location.  
         [0021]     The main body of the latching device  13  contains a contoured guideway  22  for slidable receipt of the pin  16  connected to its associated drawer  11 . As will be seen, the guideway  22  has an entrance  23  below an angled face  24  of the body. From the entrance  23 , the guideway  22  extends upwardly at an acute angle to a backward position  25 , from which it then extends downwardly to a pocket  26 . The wall of the guideway  22  just above the pocket  26  is formed with a spring finger  27 , with a small rounded protrusion  28  extending into the guideway. When the latching device  13  is moved upwardly relative to its associated pin  16 , the pin moves into the pocket  26 , resiliently biasing the spring finger  27  on its way as it does so. The spring finger  27  returns to its original position when the pin  16  sits in the pocket  26 , thereby holding the pin in that position. This is enough to hold the connecting member  14 , with all the latching devices  13  attached, in its blocking position, i.e. preventing it from falling back to its unblocking position under gravity.  
         [0022]     The body of the latching device  13  also features a spacer  29 . The purpose of this spacer  29  is to pick up on the runner  12  of the drawer  11  and thereby distance the latching device  13  by the appropriate amount from this level. This sets the latching device  13 , and in particular the entrance  23  to its guideway  22 , at the correct level to engage its associated pin  16 .  
         [0023]     The pin  16  for each drawer  11  may simply take the form of a dowel or peg fitted in a suitable hole pre-drilled in the side of the drawer. With such arrangements, the exact position of the pins is governed by the pre-drilling and the latching device can be designed accordingly so as to engage it properly. Nowadays, however, drawer runners have come on to the market which allow for some vertical adjustment of the drawer relative to its runners. With such arrangements, it may no longer be appropriate to use pins that are fixed to the drawers, because their exact position relative to the cabinet may vary, in some instances by more than an allowable tolerance, with the result that the locking mechanism will not work properly. As an alternative, therefore, as seen in  FIG. 4 , a pin member  30  is provided which is designed to clip onto the drawer-side rail of the drawer runner  12 . The drawer-side rail of the drawer runner  12  remains at a fixed level relative to the cabinet  10  even if the position of its associated drawer  11  is adjusted.  
         [0024]     As seen in  FIG. 4 , the pin member  30  has an upstanding body from which pin  16  extends out at the top and from which an arrangement of resiliently flexible feet  31  extend down at the bottom. The feet  31  are designed to engage in pre-formed holes  32  in the drawer-side track of the drawer runner  12  by means of a snap action. The precise location of the pin  16  along the length of the drawer runner  12  is accurately determined by the pre-formed holes  32  and the fixing arrangement means that the pin member  30  is held fast in this position.  
         [0025]      FIGS. 5   a  and  5   b  illustrate schematically how the pins  16   a,    16   b  of two drawers co-operate with their associated latching devices  13   a,    13   b.    FIG. 5   a  shows the position where the two drawers are closed. The pins  16   a,    16   b  are engaged in the guideways  22  of their associated latching devices  13   a,    13   b.  In this position, either drawer is free to open.  FIG. 5   b  shows the position after the upper drawer has been opened in the direction of arrow A. The upper pin  16   a  has moved in the direction of arrow A together with its associated drawer. This lateral movement of the upper pin  16   a  has acted on the ramped surface  33   a  of the guideway  22   a  of its associated latching device  13   a,  causing the latching device to move upwardly in the direction of arrow B. Latching device  13   a  moves upwardly because it is attached to the connecting member  14 , which is itself constrained to move up or down in its groove in the inside face of the cabinet. Since the lower latching device  13   b  is also attached to the connecting member  14 , this also moves upwardly in the direction of arrow B by the same amount. As will be seen, the upward movement of the lower latching device  13   b  in  FIG. 5   b  means that the pin  16   b  of its associated drawer is now located in the pocket  26   b  of the guideway  22   b  of its associated latching device  13   b.  In this position, the pin  16   b  is unable to move laterally. Thus, the lower drawer is prevented from opening. The connecting member  14 , with the two latching devices  13   a,    13   b  attached, is held in this upper position by means of the protrusion  28   b  on the spring finger  27   b  in the lower latching device.  
         [0026]     When the upper drawer is closed again, it will be seen that its associated pin  16   a  will move in a direction opposite to arrow A and strike the opposite ramped surface  34   b  of the guideway  22   a  of its associated latching device  13   a,  causing the latching device to move downwardly again, together with, via the connecting member  14 , the lower latching device  13   b.  The locking mechanism thus returns to the position shown in  FIG. 5   a.    
         [0027]     If desired, the furniture item may include means operable by a key for locking all the drawers. This would operate simply to move the connecting member upwardly so that each pin is seated in the pocket of its associated latching element, thereby blocking movement of all the pins and their associated drawers.  
         [0028]     It will be appreciated that the drawer locking mechanism is intended primarily for use in knock-down furniture and the process of fitting the latching devices to the connecting member will normally take place prior to assembly of the furniture item using a component of the furniture item that has been provided with fixing holes for the drawer runners. Preferably the actual fixing holes will be used for locating the latching devices while the connecting member is connected to them. However, it is possible, although not preferred, to provide dedicated reference holes at predetermined distances from the fixing holes.  
         [0029]     It is to be understood that numerous variations and modifications to the preferred embodiments of the invention may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.