Abstract:
A latch device intended for use with sliding and hung window systems. The latch device has a body ( 10 ) and a latch element ( 11 ) which is moveable between a latching position where it projects from the body ( 10 ) and a non-latching position where it is retracted into the body. A slide element ( 15 ) in a body ( 14 ) is coupled to a movable sub-housing ( 12 ) so that movement of the sub-housing ( 12 ) by the slide element ( 15 ) causes the latch element ( 11 ) to be moved. The body ( 10 ) is insertable into an opening in a window section and snap locks in place by the action of fingers ( 27 ) and face plate ( 18 ) acting on opposite sides of the window section adjacent the opening. The latch device can thus be fixed into a window section without any additional fasteners.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a latch and method of mounting same. More particularly but not exclusively the latch and method of mounting is intended for use with sliding and hung window systems. 
     Typically latches for sliding and hung window systems are surface mounted. Thus they are readily visible on the window and can therefore adversely impact on the aesthetic appeal of the window installation. 
     Surface mounting latches are normally attached to the window by use of mechanical fasteners. In time the latch can become “loose” on the window due to loosing of the mechanical fastener or in extreme cases the opening in the window extrusion in which the fastener is fitted can become oversized and the latch can become separated from the window. Generally this oversizing of the opening results from the fastener initially becoming loose. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a latch which is in a large part concealed within a window extrusion. 
     It is a further object of the present invention to provide a latch which is of such construction that no fixing screws or other mechanical fasteners are required for installation of the latch in a window system. 
     Broadly according to one aspect of the present invention there is provided a latch device including a body, a latch element movably mounted within the body and movable between a latching position and non-latching position, moving mechanism for moving the latch element between said latching and non-latching positions, the body having retaining elements to retain the body when installed through an opening and into a window extrusion. 
     In a preferred form of the invention the latch device further includes an externally accessible operating slide element which is engageable with said moving mechanism. The slide element can be slidingly engaged with a mounting member which is mountable in a snap lock arrangement in an opening in a window extrusion. The coupling between the slide element and the moving means can be formed by inter-engagement of an elongate member in an aperture. 
     According to a preferred form of the invention the moving mechanism includes a sub-housing slidingly located in the body, the latch element being pivotal about an axis fixed relative to the body and coupled to the sub-housing such that sliding movement of the sub-housing translates into a pivotal movement of the latch element. 
     Preferably a biasing means is coupled between the body and the sub-housing. The latch element is preferably a hook tongue. 
     According to a second broad aspect of the invention there is provided a method of mounting a latch device in an extruded window element the method including the steps of forming apertures in opposing spaced apart walls of the window element, inserting through one aperture in a snap lock fitting a latch body of the latch device so that the body is substantially located within the extruded element and installing in the other aperture operating furniture which when installed inter-engages with latch moving means of the latch body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following more detailed description of a preferred embodiment of the invention reference will be made to the accompanying drawings in which: 
     FIG. 1 is a perspective illustration of the latch when in the “locked” position and with a cover of the housing removed for better illustration, 
     FIG. 2 is a further perspective view of the latch as shown in FIG. 1 but with the cover installed and without the operating “furniture”, 
     FIG. 3 is a further perspective view of the arrangement shown in FIG. 2 but with the cover removed, 
     FIG. 4 is a view similar to FIG. 3 but with the latch in the unlocked position, 
     FIG. 5 is a perspective view in disassembled form of the operating furniture, 
     FIG. 6 is a further perspective view of the disassembled operating furniture, 
     FIG. 7 is a plan view of the housing of the latch, 
     FIG. 8 is a face elevation view of the housing shown in FIG. 7, and 
     FIG. 9 is an end elevation view of the housing shown in FIGS.  7  and  8 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The latch according to the preferred embodiment shown in the drawings includes a main housing  10 , a lock beak  11 , a sub-housing  12  and operating furniture  13 . The operating furniture  13  includes a body  14  and a slide  15  with an integral gripping projection  16 . These elements of the construction of the latch are shown in FIG. 1 where a cover  17  (see FIG. 2) of the housing  10  has been removed for the purposes of illustration. 
     The housing  10  has an integral faceplate  18  with an opening  19  through which the hook beak can move from its retracted (unlatched) position to the projecting (latched or locked) position. 
     Disposed parallel to but spaced from faceplate  18  is a wall  20  which like faceplate  18  extends at right angles to the floor  23  of the housing  10 . This wall  20  also has an opening  21  through which projects a stub shaft  22  from sub-housing  12 . The slot  21  is of sufficient length to accommodate the movement of the stub shaft  22  during sliding movement of the sub-housing  12  in housing  10  as will hereinafter be described. 
     Extending between cover plate  18  and walls  20  and also at right angles to the floor  23  are end walls  24 . These end walls  24  kink inwardly toward the faceplate  18  to form a recess  25 . A resilient arm  26  extending from wall  24  is located adjacent each recess  25 . The arm  26 , which is integrally formed with wall  24 , extends outwardly at an angle to the plane of wall  24  and is slightly cranked at its distal end  27 . 
     Projecting from the floor  23  of the housing  10  is a spigot  28 . This spigot extends through a pair of aligned slots  29  in the respective spaced apart and parallel walls  30  of the sub-housing  12 . The hook beak  11  has an opening  31  in the main body  32  thereof and this is journal onto spigot  28 . The hook beak  11  can thus rotate about the axis of the spigot  28 . 
     Coupled to a flange  33  extending from an end wall  34  of the sub-housing  12  is a spring  35 . The other end of the spring  35  is coupled to a pin  36  which is mounted with the housing  10  by projecting upwardly from floor  23 . 
     The sub-housing  12  is aligned for longitudinal sliding movement within the main housing  10  by an abutment  37  which extends inwardly from the inside surface of wall  20 . This abutment  37  engages with the sidewall  38  of sub-housing  12 . A plurality of projections  39  extend from one of the walls  30  of the sub-housing  12  and slidingly engage with the inside surface of faceplate  18 . Accordingly, when the cover  17  is in place the sub-housing  12  can slidingly move within the housing  10  between the positions shown in FIGS. 3 and 4 which correspond with the latching position and in the unlatched position. 
     Extending from each of the walls  30  are a pair of oppositely disposed spigots  40 . These slidingly engage in a slot  41  formed in the main body  32  of the hook beak  11 . The slot  41  has an angled end  41   a . It is in this end  41   a  that the spigot  40  resides when the hook beak  11  is in the latched position as shown in FIGS. 1-3. 
     Referring to FIG. 4 the latch is moved from the unlatched position to the latched position by moving sub-shaft  22  in the direction of arrow A. This causes the sub-housing  12  to slide within the housing  10 . This sliding movement results in the spigots  40  sliding along slot  41  which causes the hook beak  11  to rotate about the axis of spigot  28 . At the end of the travel the spigots  40  move into portion  41   a  of the slot. 
     Because end portion  41   a  is not aligned with the main length of the slot  41  it is not possible for someone wishing to gain unauthorised access to manipulate the tongue in such a way as to apply a force which would cause the hook beak to rotate about the axis of spigot  28 . Consequently, there is an inbuilt dead latching function achieved when the sub-housing  12  has moved to its fullest extent in the latching direction A. This means that the hook beak  11  when in the deadlocked position can only be moved by moving the stub shaft  22  in a direction opposition to arrow A i.e. toward the unlatching position. 
     It will be noted that the spring  35  applies a spring bias to the sub-housing  12  when in the unlatched position. This ensures that the hook beak  11  remains in the retracted position. 
     The operating furniture consists of a body  11  which forms a recessed area in which the slide  15  is movable. The floor  43  of the recessed area  42  includes an elongate slot  44 . 
     Projecting from the underside of slide  15  is a tapered projection  45  which has a bore or opening  46  within which the end of the stub shaft  22  can engage. Where the tapered projection  45  extends from the main body of the slide  15  a pair of opposed slots  47  are formed. Thus to assemble the slide  15  with the body  14  the tapered projection  45  is forced through slot  44  until the long edges of the slot  44  slidingly engage in slots  47 . Therefore, effectively slide  15  is fitted in a “snap lock” fitting arrangement with body  14 . 
     On the external of the surfaces of the long walls  48  of wall  49  are a pair of spaced apart ramps  50 . The ramps  50  are spaced from the shoulder  51  formed by rim  52  of the body  14 . The spacing is about the same as the thickness of material surrounding a shaped opening formed in the window extrusion into which the well  49  is inserted during installation of the latch. Thus, once again a snap-lock fitting is used when installing the body  14  in the opening formed in the window extrusion. 
     Similarly, an opening is formed in the window extrusion opposite that in which the body  14  of the operating furniture is inserted. This opening is sized so as to accommodate the length and height of the body  10  but is less than the overall dimensions of the faceplate  18 . The body  10  is thus inserted through this opening and as it does so the fingers  26  move resiliently into the recesses  25  but spring back when the housing is pushed fully home into the window extrusion thereby capturing the housing  10  within the extrusion. Generally the housing  10  will be installed in the window extrusion before the operating furniture so that the slide  15  can be correctly aligned for engagement of the sub-shaft  22  through opening  46  in the tapered projection  45 . 
     No fixing screws are therefore required in either assembly of the latch or its installation. As described above the operating furniture and the latch body  10  are simply snap-locked into place in the window extrusion. This results in the mechanism of the latch essentially being located within the window extrusion while the only visible feature will be the rim portion and slide within the recess  43  visible. However, these features can, as illustrated in the drawings, be made aesthetically pleasing in appearance and will, therefore, not detract from the visual appearance of the window. 
     Likewise, the latch itself can be assembled without the need for any fixing screws. By slightly parting the walls  30  of the sub-housing  12  sufficient clearances is provided for insulation of the hook beak  11 . Upon release of the walls  30  the spigots  40  engage from either side into slot  41 . The sub-housing  12  with installed hook beak  11  can then be placed in the housing so that the opening  31  in the hook beak body  32  engages over spigot  28 . Once the spring  36  has been installed the cover  17  can be positioned and put in place and retained by say dowels formed integrally with the cover  17  interference fitting in openings  53  in the floor  23  of the housing  10 . 
     The present invention thus provides a latch for sliding and hung window systems. The main latch mechanism is concealed within the window extrusion and fits in a snap-lock type fitting. Likewise, the operating furniture is in part recessed into the window extrusion and snap-locks in place. The only readily visible part of the overall latch assembly can, therefore, be made unobtrusive and aesthetically pleasing in appearance.