Abstract:
A lock mechanism primarily intended for a sliding door or window application. The lock mechanism includes a lock body ( 10 ) with a lock beak ( 21 ) rotatably mounted therewith and biased by a bias element ( 23 ) to a first position. The lock beak ( 21 ) is co-operable with a hook ( 20 ) of a strike ( 13 ) upon the hook engaging in the body whereby the lock beak ( 21 ) rotates to a second position against the bias of biasing element ( 23 ). Operating members ( 27  and  28 ) within the lock body ( 10 ) are operable by external actuating elements such that the operating members can be independently operated to cause the lock beak ( 21 ) to move from said first position to said second position and one of the operating members to retain the lock beak in said first position.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to a lock mechanism. The lock is primarily intended for a sliding door or window application. 
   In the following disclosure the door lock according to the invention will be described in the context of a mortice lock. However, it will be apparent to those skilled in the art that the lock mechanism in one or more of its possible forms could also be incorporated in a housing intended for rim or surface mounting. Consequently while the following description will describe a mortice lock any reference to lock housing or lock body should be read in the context of the housing or body being suitable for a mortice lock mounting i.e. within the door or a rim/surface mounting application. 
   Mortice locks for e.g. sliding doors provide a number of functions such as simple latching and unlatching of the door, so called day latching and deadlocking. To achieve these functions one lever is provided for latching, another lever or the like for day latching and a key cylinder for deadlocking. Visually the lock furniture associated with the lock takes on a “very busy” appearance resulting from the two levers and key cylinder. This also tends to restrict the size of the levers which can be used, otherwise the levers can be difficult to access and use. Thus, there are issues of appearance and user friendliness associated with existing locks. While these are manifested in the externally visible lock furniture the construction and arrangement of the lock mechanism dictates the number and/or type of external levers, snib etc. and position of the key cylinder. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a lock which requires only a single actuation lever on both interior and exterior sides of a closure with which the lock is associated in order to achieve latching and day latching functions. 
   Broadly according to one aspect of the invention there is provided a lock mechanism including a lock body, a lock beak rotatably mounted within the lock body, a biasing device which bias the lock beak to a first position, a strike having a hook, the hook co-operable with the lock beak when the hook is engaged in the body, and the lock beak is in said first position, operating members within the lock body operable by external actuating means, the operating members being operatively mounted such that they can be independently operated to cause the lock beak to rotatably move against the bias of the biasing device from said first position to a second position to remove the engagement between the hook and lock beak and one said operating member being operable to retain the lock beak in said first position. 
   Preferably the lock further includes means to prevent the other of the operating members from being operable to retain a lock beak in said first position. 
   According to one form of the invention the lock includes a slide member operable by a lock cylinder to effect a deadlocking function. 
   Preferably the slide member provides a mounting for at least one shoot bolt. 
   The slide member preferably includes a first engagement means which is engageable with the lock beak to cause deadlocking of the lock beak in the first position. Preferably the slide member includes a second engagement means which is engageable with at least one of the operating members to prevent operation thereof by the external actuating means. 
   The lock preferably further includes a retention spring means which is engageable with a cam of a lock cylinder to retain the cam when in the position which corresponds to the slide member having been moved by the cam to a deadlocked position. 
   Preferably the retention spring additionally applies a detent to the slide member when the slide member is in the non-deadlocking position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following more detailed description of the invention reference will be made to the accompanying drawings in which: 
       FIG. 1  is a perspective view of the lock with a cover plate of the lock body/housing removed to show the componentry of the lock mechanism, the lock being shown in the unlatched position but in juxtaposition with a strike, 
       FIG. 2  is a view similar to  FIG. 1  but with the lock mechanism in its initial operation of movement of a locking beak interengaging with the strike, 
       FIG. 3  is a perspective view of part of the section of a sliding door with the lock mechanism according to the present invention mortice mounted therein and associated with internal and external latch furniture, 
       FIG. 4  is a reverse view of the arrangement shown in  FIG. 3  but further incorporating the strike, 
       FIG. 5  is a further perspective view of the sliding door section with furniture and strike but from a viewpoint different to that of  FIG. 4 . 
       FIG. 6  is an inside face view of an item of lock furniture for use with the lock according to the present invention, 
       FIG. 7  is an elevation view of the arrangement shown in  FIGS. 1 and 3  but with the lock mechanism moved to the day latched position where the lock beak has engaged with the strike and the lock beak is engaged by a sliding foot to prevent the lock beak from being actuated, 
       FIG. 8  is a perspective view of the lock mechanism as shown in  FIG. 7  but with the mechanism having advanced further in its latching operation, 
       FIG. 9  is a side elevation view of the lock according to the present invention, 
       FIG. 10  is a section on line D—D of  FIG. 9 , 
       FIG. 11  is a view similar to  FIG. 8  but showing the top and bottom shot bolts in the unlocked position, 
       FIG. 12  is a side elevation view with the lock in the configuration shown in  FIG. 11 , and 
       FIG. 13  is a cross-section view taken on line B—B of  FIG. 12 . 
   

   DETAILED DESCRIPTION 
   The lock includes a lock body or housing  10  into which the various components of the locking mechanism (as hereinafter described) are fitted. The housing  10  is closed by a cover which is not shown in the drawings so that the internal workings of the lock can be shown. The housing  10  further includes a front edge faceplate  10   a  and a rear wall  10   b.    
   In a mortice application the housing  10  is engaged through or in a generally rectangular shape opening formed in the section S of the door. The housing  10  therefore locates within the internal cavity of the door section S with the faceplate  10   a  fastened to an exterior surface of the side edge of the section S (see  FIG. 3 ). 
   The lock is, as normal, associated with furniture components. On the interior side of the door the furniture component comprises a D-handle  14  with a mounting escutcheon  15 . Mounted with the escutcheon  15  is a latching lever  16 . Extending through an opening in escutcheon  15  is one end of a double lock cylinder L. 
   On the exterior side of the section S there is provided a pull  17  with associated mounting escutcheon  18 . Extending through an opening in escutcheon  18  is the other end of the lock cylinder L. A latching lever  19  is also mounted with the escutcheon  18 . 
   The lock beak  21  of the lock locates adjacent an opening  22  in the faceplate  10   a . A hook  20  of strike  13  is engageable through opening  22  as can be seen for example in  FIG. 1 . 
   The lock beak  21  is pivotally mounted about an axis established by a pair of stub axles  25  which are journaled in suitable bearing areas (not shown) of the housing  10  and cover plate. A sliding foot  23  engages with the lock beak  21  adjacent the hooked end thereof. The sliding foot  23  is biased by a compression spring  24 . 
   The lock is therefore self-latching. When the door is moved into the closed position the hook  20  of the strike  13  engages through opening  22  and contacts the lock beak  21 . The ramp surface  26  of the strike hook  20  engages with the hook position of lock beak  21  causing the lock beak to ride upwardly about the axis of sub-axles  25  and against the action of the spring biased sliding foot  23 . Consequently, once the lock beak  21  clears the ramp  26  of the hook strike  20  the spring  24  drives the sliding foot  23  downwardly thereby acting against the lock beak  21  to latch it on to the lock strike  20 . 
     FIG. 1  shows the lock beak  21  having cleared the ramp  26  and being acted upon by the sliding foot so that ultimately the sliding foot  23  will ensure that the lock beak  21  engages with the strike hook  20  as shown, for example, in  FIG. 11 . 
   The lock can be unlatched using both interior and exterior latching levers  16  and  19  respectively. Each of the latching levers  16  and  19  has a square drive portion e.g. the drive portion  19   a  of lever  19  (see  FIG. 6 ) which extends into cam  28  which is rotatably mounted within the housing  10 . For example, referring to  FIG. 1  the square drive  19   a  of exterior lever  19  will engage within square section opening  29  of the cam  28 . Likewise a square drive portion of the interior latching lever  16  will co-operatively engage with cam  27 . 
   The latching levers  16  and  19  can thus be rotated individually to act on the lock beak  21 . This is achieved by an arm  30  or  31  of the respective cams  27  and  28  acting against an abutment portion  32  of the lock beak  21 . The action of rotating the latching lever therefore results in the lock beak rising against the sliding foot  23  and out of engagement with the strike  13 . Once the strike  13  has moved out of the housing  10  and the latching lever  16  or  19  is released the lock beak  21  will return to its horizontal or rest position under the action of the sliding foot  23 . 
   The lock can be latched internally by a manual operation of the internal latching lever  16 . The external latching lever  19  drives a handing disc  33  (see  FIG. 6 ) with its square drive  19   a  which will not allow the lock to be day latched from the outside. 
   The handing disc  33  is housed in the exterior escutcheon  18 . A lug  34  formed on the inside of the escutcheon  18  engages in an arcuate slot  35  in the handing disc  33 . The lug  34  abuts one end of the slot  35  thus preventing the latching lever  19  being moved in a direction would be necessary in order to day latch the mechanism. The handling disc thus prevents the lock being placed into the day latched condition from the outside of the door only. This overcomes a problem which could arise if the lock were able to accidentally be day latched as a user exits the door thereby preventing other users from being able to open the door from the inside. 
   The lock is manually latched when the interior latching lever  16  rotates one of the cams  27 / 28  so that the surface  36  at the end of the arm  31  is adjacent or in contact with surface  37  of the sliding foot  23  (see  FIG. 7 ). The cam  27  or  28  (cam  27  in the configuration shown in  FIG. 7 ) is held in place by the detent spring  38 . Because of the juxtaposition of the end  36  of arm  31 , as shown in  FIG. 7 , with the surface  37 , the sliding foot  23  cannot slide against the bias of the compression spring  24  and thereby release the lock beak  21 . 
   The lock can be deadlocked via the lock cylinder L from both interior and exterior keys. The key activates cam  40  of the lock cylinder L. This cam  40  acts upon a bottom shoot bolt  41  and a top shoot bolt  42  which are joined and act as one. In effect there is a single slide member which forms shoot bolts  41  and  42 . The cam  40  therefore “lifts” the shoot bolts  41 / 42  so that a projection  43  thereof (see  FIG. 8 ) engages with a downwardly projecting portion  44  of the lock beak  21 . Similarly a projection  45  of the shoot bolt  41 / 42  engages with hook shaped portions  46  and  47  of the respective cams  27  and  28 . This prevents the lock being unlatched via the latching levers  16  and  19 . 
   The shoot bolt  41 / 42  can also be used to activate and deactivate remote locks (not shown) in the door for added security. Alternatively, the top shoot bolt  41  can be coupled to a rod which projects through the top of the door and into a keep in the top frame member of the door surround. 
   When cam  40  of the lock cylinder L is rotated, for deadlocking, the cam  40  rides against a cam retention leaf spring  50  which is mounted with the sidewall  10   b  of the housing  10  in the vicinity of an opening in the sidewall  10   b . The cam retention leaf spring  50  over centres the cam  40  and thus prevents the shoot bolts  41 / 42  from being manipulated to un-deadbolt the lock. 
   The cam retention leaf spring  50  also acts as an additional detent against shoot bolt  41  in cavity  51  for the unlocked position (see  FIG. 11 ) and in cavity  52  for the locked position (see  FIG. 8 ). As will be appreciated all of these functions are thus accomplished with one component namely the combined shoot bolts  41 / 42 . 
   Detent springs  38   a  also provide a detent action with shoot bolt  41 . 
   The lock cannot be lifted off the strike  13 . The lock housing  10  has a ramp surface  53  and associated step  54  (adjacent the opening  22 ) which can act against the underside  55  and associated step  56  of the strike  20  in the event that an attempt is made to try and lift the lock off the strike. Furthermore, the strike has an abutment surface  57  which engages with an edge of a cover plate  10   a  at opening  22 . These features combine to prevent any vertical lift of the door in an effort to unlatch the lock. 
   The lock according to the present invention provides an effective yet straightforward lock construction which provides a number of desirable features. These include:— 
   An internal lever  16  which has a combined action of both opening and day latching the lock mechanism. 
   A spring element  50  which achieves functions which are normally achieved by separate components in known lock constructions. The spring  50  provides a deadlocked condition of the slide element (forming the top and bottom shoot bolts  41 / 42 ) via interaction of the cylinder cam  40 . It also provides a detented bias of the slide  41 / 42  in both the deadlocked and un-deadlocked state. 
   The handing disc  33  prevents the external lever  19  from activating the day latch state. 
   An anti-lift feature incorporated into the design of the strike  13 . 
   The lock of the present invention thus enables use of a single actuation lever and cylinder on both the interior and exterior sides of the closure with which the lock is associated. This provides advantages such as improved visual appearance of lock furniture and the use of actuation levers of a size that are easier to use. It is also believed that the lock design will be such that it is more intuitive to use from a dwellers point of view. From a manufacturers viewpoint it is believed there will be reduced costs of manufacture by reducing the number of levers that need to be manufactured. 
   Other features of the lock will be apparent to those skilled in the art. Also it will be apparent to those skilled in the art that the lock mechanism as described herein is open to modification within the scope of the invention.