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FIELD OF THE INVENTION 
       [0001]    This invention relates to a tilt latch mechanism for use in a pivotable sash window, and more particularly to a latch housing designed for ease of installation while ensuring integrity of the latch installation during window deformation accompanying high wind loads. 
       BACKGROUND OF THE INVENTION 
       [0002]    The traditional style of windows used in the United States, and many other places that had been colonized by the English, is the single-hung and the double-hung sash window. A Double-hung window assembly typically comprises two sash windows each of which slide vertically in a master frame. To enable a user to easily open or close such windows, as well as to enable the window to remain static once it has been opened or closed, a balance assembly is attached to each window. Such balance assemblies were originally just counterweights on either side of the window, where the weights were suspended by a cord or chain across a pulley and attached to the sash window. 
         [0003]    Advances in window construction have been significant, and although contemporary windows may visually resemble their ancestor described above, a resemblance which may even permit its use as a replacement window in historic homes, the technological improvements render them very different as to the materials used, and vastly superior in terms of performance. Many of the changes have been due in part to the demand for greater energy efficiency in both hotter and colder climates, where the savings attributable to reductions in the corresponding air-conditioning or heating expenses can be considerable. 
         [0004]    Increases in thermal efficiency have been made through the use of an Insulating Glass Unit (IGU) or double-paned window, in which two panes of glass are hermetically sealed to form a single glazed unit, with an ‘air-space’ between the two panes of glass. This arrangement, also known as “double-glazing,” generally reduced or eliminated the problem of windows fogging or frosting, and of the windows being uncomfortably cold upon contact. Further improvement were made by filling the ‘air-space’ with inert gases, such as argon and krypton, both of which have a higher resistance to heat flow than does air. Additional thermal resistance of an IGU has also been achieved through the use of low-emissivity coatings, which are typically applied to the non-exposed, interior side of the glass pane or panes. The coatings can be alternatively designed for a high or low solar heat gain coefficient (SHGC), depending on the location&#39;s requirements, while simultaneously reducing the window&#39;s u-factor, or rate at which the unit conducts infrared radiation (non-solar heat) from a warm pane of glass to a cooler pane of glass. 
         [0005]    Despite these tremendous advances, a further consideration as to the overall energy efficiency of a window is that the window&#39;s frame constitutes roughly 25% of its area, making its conductivity a substantial factor in the window&#39;s energy performance. Wood frame windows are still widely available, however, the maintenance drawbacks of solid wood windows has led to some of the material upgrades previously mentioned, as frames have become available in the form of vinyl-clad and aluminum-clad wood, and such frames actually comprise a major share of the market. Not surprisingly, the market for energy conductive aluminum frame windows is relatively small. But a large intermediate share is held by insulated vinyl and insulated fiberglass frame windows which are among the best energy performers. 
         [0006]    Advances have similarly been made in the associated window hardware, including the latch which enables a sash window to not only move vertically, but to pivot inwardly as well. One such latch is shown by U.S. Pat. No. 5,139,291 to Schultz. The latch is adapted for installation into a window having a hallow top sash rail. The latch housing has a “side wall rail,” which, in combination with the housing cover edge, forms a groove, where the groove cooperates with the edge of the top wall of the top sash rail to retain the latch. The latch slides into a side opening in the sash window stile, which has a periphery to match the latch profile. A tab on the front face of the latch engages the stile to retain the tilt latch in position. 
         [0007]    However, many if not most coastal areas now mandate that the windows installed be constructed to satisfy very stringent standards. These standard may include a requirement that the window be able to structurally withstand, for a set period of time, a specified design pressure, which would permit the window to maintain its integrity throughout the sustained winds of a category five hurricane. Under such loading, it is not uncommon to see a window convex a couple of inches, but when properly designed, the window will regain its original form. This significant deformation under such high wind loads creates as serious if not fatal problem for the hardware currently available, particularly the tilt latch. The Schultz tilt latch would not be retained by the sash rail as described above, when the window experienced high wind loading and deformation, especially in the case of a vinyl frame window, which lacks the structural rigidity of the energy inefficient aluminum frame window. 
         [0008]    It is possible to utilize the top plate of the latch to restore some of the frame&#39;s structural rigidity, and may be accomplished in the approach shown in FIG. 3 of U.S. Pat. No. 7,069,694 to Fullick. The top plate in Fullick widens to permit the installation of mechanical fasteners which connect the top plate to the opposite sides of the top wall of the top rail. Although this approach would help to limit the local window frame deformation which would impair the integrity of the latch installation during loading and deformation occurring in extreme weather conditions, it requires additional parts and manufacturing operations not needed with the Schultz configuration. The Fullick design also affects the aesthetic appearance of the latch, which is a significant factor in a competitive market where such a tradeoff, for the most part, may not enhance overall value to the consumer because statistically speaking, the ability of the latch to satisfy high wind loading conditions of extreme weather phenomena will seldom be utilized. 
         [0009]    Also, the latch in U.S. Pat. No. 5,671,958 to Szapucki has resilient tabs 18, 18′, 20, and 20′, as shown in its FIG. 12, which permit a drop down latch installation into the top rail of the window, rather than an installation endwise through an opening in the stile. These tabs in Szapucki are designed to be resilient so that they snap outwardly under the edges of the top plate. The tabs may assist in keeping the latch in place while the window experiences some minor deformation associated with ordinary use and loading, but the tabs are extremely limited by their design and inherent ability to withstand large scale deformations that accompany the high wind loading conditions. 
         [0010]    The invention disclosed herein provides a more advanced and unique concept for installation than provided by Schultz, and without the inherent drawbacks created by incorporation of the Fullick top plate and fasteners. This invention furthermore overcomes the limitations posed by attempting to use other existing designs represented by the Szapucki patent. 
       SUMMARY OF THE INVENTION 
       [0011]    The latch of this invention is designed to be able to maintain the integrity of a latch installation and its functionality, even when a window undergoes substantial deformation, which may occur as a result of the high sustained winds experienced during hurricanes, as well as the high winds associated with other extreme weather phenomena. The latch features disclosed herein may be utilized on number of different latch types, but they are particularly useful for a latch to be installed on the sash window of a tiltable single-hung or double hung window assembly. 
         [0012]    The latch of this invention comprises a latch housing, which may comprise a pair of side walls extending down from a top plate, where the top plate extends beyond the side wall and may be used to install the latch onto the top rail of a hung window. Although not required, the housing may further comprise a bottom wall and a back wall, where the bottom and back walls may connect to at least a portion of the side walls. The bottom wall may assist in forming a cavity to retain a latch bolt, however, the latch bolt may also be retained by other means, such as, but not limited to, a lip on the end of the side walls, etc. 
         [0013]    A latch bolt with a tapered nose may be disposed in the housing so that the nose extends out from an opening in one end of the housing, and be biased into an extended position. The nose may be designed and shaped to co-act with a side jamb flange. Biasing may be accomplished by a spring means such as, but not limited to, a compression spring, a tension spring, etc. Protrusions or stops or other such features may be provided on the latch bolt or the housing or both the latch bolt and the housing, to limit the travel of the latch bolt in the extended position. The latch bolt may comprise a top wall, a pair of side walls, a bottom wall, and a rear wall. A raised area on the top wall may protrude through an opening in the latch housing to provide a means of retracting the latch bolt, where the raised area may be in the form of a button. The button may be integral to the latch bolt or may be a separate part that is attached to the latch bolt. The button may be attached to the latch bolt by any number of methods including, but not limited to, bonding, using mechanically fasteners, or, as in the preferred embodiment, using hook-shaped spring clips which are inserted through an opening in the top wall of the latch bolt and thereafter catch upon the underside of the top wall. Also, the top wall may further comprise a recess adjacent to the raised area to provide an increase in the surface area upon which a user may apply a force to toggle the latch bolt. 
         [0014]    The latch of this invention further comprises a cantilevered member that occupies a normal “rest” position at an angle to the housing side walls. The cantilevered member may extend from the housing side wall or alternatively from a housing bottom wall, if a bottom wall is incorporated as part of the latch housing. The cantilevered extension may be an integral part of the housing side or bottom wall, and may be formed so as to normally protrude away from a vertex on the housing, at an angle relative to the side wall. As an alternative to forming the cantilevered member as an integral part, a separate part or wall segment may be connected to the housing to function in the same manner as the integral member. 
         [0015]    Biasing of the cantilevered member may be employed to maintain contact between the cantilevered member of the latch housing and the window structure. With an embodiment where the cantilevered member is integral to the housing side or bottom wall, biasing may be accomplished in a number of ways, including, but not limited to, incorporating a spring to bias the cantilevered member into the angular position, where the connection around the region of the vertex is merely a flexible connection. Another biasing scheme for an integral cantilevered member may involve forming the connection between the cantilevered member and the housing, around the region of the vertex, from a resilient material. With this means of biasing, the forming of the connection around the vertex must be such that the cantilevered extension should normally occupy an unstressed, “rest” position while extended at an angle to the housing, such that deflecting the cantilevered member so as to be pressed up against the housing would created stored elastic strain energy in the resilient connection. Once the force that deflected the cantilevered member up against the housing was released, as the latch is installed in the window, the stored strain energy would seek to return the cantilevered member to the angled position. The restorative force of the resilient connection would enable positive contact between the cantilevered extension and the window&#39;s top wall of the top rail. 
         [0016]    The biasing of a separate cantilevered member in the form of a wall segment offers similar as well as other possible configurations of the invention. The wall segment, comparable to the integral cantilevered member, may have either flexible material at the vertex accompanied by biasing with a spring, or it may have resilient material around the vertex which normally biases the cantilevered member to the angled position. The separate cantilevered member in the form of a wall segment may need to be attached to the housing. Attaching a separate side wall segment, while providing either the flexible or the resilient vertex region, may entail having a flange extending away from the vertex and opposite the cantilevered portion, where such a flange may provide an area for accomplishing attachment to either the housing side wall or bottom wall. Attachment of this flange could include, but is not limited to, use of mechanical fasteners, bonding of the flange to the housing, etc. A separate wall segment may alternatively be attached to the housing with a hinged connection. With a hinged connection, the wall segment would be free to rotate and would need a means of biasing the wall segment to the angled position, which may include, but is not limited to, a compression spring. 
         [0017]    The location of the vertex on the housing, as well as the length of the cantilevered member, may vary, and both may be designed to assure positive contact of the cantilevered member with the window structure. The closer to an end of the housing that the vertex is located, the longer may be the length of the cantilevered member. A longer cantilevered member that is properly biased would naturally be able to accommodate greater deformations in the window frame and still maintain contact. Also, locating the vertex of a cantilevered member in close proximity to one end may permit use of a plurality of such cantilevered members on one side of the housing, and in addition, a plurality of cantilevered members may be utilized on both sides of the housing. Furthermore, the cantilevered member may have a vertex and arrangement such that the cantilevered member angles away from the housing, with the displaced end of the cantilevered member disposed towards the interior of the window. Alternatively, as in a preferred embodiment, the vertex and arrangement may be such that the cantilevered member angles away from the housing, with the displaced end of the cantilevered member disposed towards the stile of the window. 
         [0018]    For any of these possible configurations, installation of the latch bolt may be accomplished through an opening in the window stile that matches the end profile of the latch, and with an opening in the top wall of the top rail contoured to match the housing side walls and back wall. When installing the latch in the window by inserting the latch into the opening, the cantilevered member may need to be pushed against the latch housing until it is past the opening, in order to prevent it from catching on the opening. The latch may be retained in the window opening by have a flexible or a resilient retaining tab on the housing side walls or bottom wall that, after insertion of the latch into the window opening, catches on the window stile and prevents the latch from working its way out from the installed position. 
         [0019]    A typical pivotable sash window would include installation of two such latches—one on each of the two stiles. As such, the two latches may be in the form of a left-hand latch, and a mirror image version, or a right-hand latch. 
       OBJECTS OF THE INVENTION 
       [0020]    It is an object of this invention to provide a latch to be installed in the top rail of a sash window of a single-hung or a double hung window assembly. 
         [0021]    It is an object of this invention to provide a latch which permits a sash window of a single-hung or a double-hung window assembly to tilt inwardly. 
         [0022]    It is a further object of this invention to provide a latch in which the latch may be easily installed in the sash window frame of a hung window. 
         [0023]    It is a further object of this invention to provide a latch in which the latch bolt may be installed in the sash window frame without the use of mechanical fasteners. 
         [0024]    It is another object of this invention to provide a latch that can be retained by the sash window frame under conditions in which the window experiences severe deformation. 
         [0025]    It is another object of this invention to provide a latch that can be retained by the sash window frame during the sustained winds of a hurricane. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a perspective view of a tiltable sash window utilizing the latch of this invention, with part of the master window frame removed to reveal latch details. 
           [0027]      FIG. 2  is an exploded view of the parts comprising a latch embodiment according to the invention. 
           [0028]      FIG. 3  is a top view of the latch according to the invention. 
           [0029]      FIG. 4  is a side view of the latch according to the invention. 
           [0030]      FIG. 5  is a side view of the latch according to the invention. 
           [0031]      FIG. 6  is a bottom view of the latch according to the invention. 
           [0032]      FIG. 7  is a perspective view of an alternative embodiment of the latch being installed into an opening in a sash window stile and top rail. 
           [0033]      FIG. 8  is an enlarged perspective view of an alternate embodiment of the cantilevered member of the latch, as the latch is installed into an opening in a sash window stile and top rail. 
           [0034]      FIG. 9  is an enlarged perspective view of the right-hand latch of this invention with the cantilevered member maintaining the integrity of the latch installation, as the window experiences severe deformation under actual high wind load testing. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0035]    A left-hand latch assembly  40  may be provided for installation in a single-hung or double-hung window assembly  10 , as shown in  FIG. 1 . The tiltable single-hung or double hung window  10  has an upper sash window  21 , lower sash window  22 , and a master frame consisting of a sill portion  11 , a head jamb  12 , and side jambs  13 . Portions of the head jamb  12  and the side jambs  14  have been cut away in the figure in order to illustrate the features of the jamb with which the latch interacts. The lower sash window  22  is comprised of bottom rail  26 , top rail  27 , and stiles  24  and  25 , which support the edge of the glazing, or glass pane  23 . As is common for tiltable single-hung or double-hung sash windows, the lower portion of the window has a connection to the frame (not shown) which is both pivotable and slidable with respect to the frame. The upper portion of the window may have latch  40  with a latch bolt  70  having a nose  76 , where latch  40  is also slidable with respect to the jamb, but where the nose  76  may be retracted to permit the lower sash window  22  to rotate inward. 
         [0036]    The latch bolt  70 , in a preferred embodiment, may be comprised of a top wall  71 , bottom wall  72 , first side wall  73  and second side wall  74 , as shown in  FIG. 2 . The latch bolt  70  may have a rear wall  75  connecting at least a portion of the first and second side walls, but in a preferred embodiment, a rear wall  75  is formed only by the thickness of the end of top wall  71 , and has a semi-circular shape. The latch bolt  70  may have a nose  76  which may be angled from the second side wall  74  towards the first side wall  73  to form a pointed edge. The first side wall  73  may, near the pointed edge of the nose  76 , have a step feature which may be specially designed to co-act with the side jamb flange  15  of the window  10 . 
         [0037]    The latch bolt  70  may have a recess  79  in the top wall  71  which may be accessible to the user through an opening  56  in the top plate of the housing  50 . The opening  56  may take many different forms including, but not limited to, a circular opening, a rectangle, an oval, a polygon, etc, and must merely accommodate access to recess  79 . In a preferred embodiment the opening  56  is a race-track shape with two straight sides connected by two semi-circular edges. The recess  79  may permit the user—using a thumb, thumb nail, finger, finger nails, or a tool—to toggle the latch bolt from the extended to the retracted position. To permit easier toggling, the latch bolt may have, in place of or in addition to recess  79 , a protruding or raised portion, which in a preferred embodiment, is in the form of a button  80 . The button  80  of a preferred embodiment may have an exposed portion  81  and a non-exposed portion  82 , where the non-exposed portion  82  may contain features to facilitate attachment of the button to the latch bolt  70 . 
         [0038]    The exposed portion  81 , in a preferred embodiment, may have a front face  83 , a top face  84 , and an angled back face  85 , such that the front face  83  would provide an easily graspable surface to enable the user to toggle the latch bolt. 
         [0039]    The non-exposed portion  82 , in a preferred embodiment, may have first and second hooked extensions or spring clips  86  and  87 , which may be inserted into an opening  78  in the top wall  71  of latch bolt  70 . The spring clips  86  and  87  and the opening  78  may be formed so as to require the spring clips to be deflected towards each other to pass through the width of the opening during installation. Once the underside of top portion  81  of button  80  contacts the top wall  71  of the latch bolt  70  during installation, the spring clips may rebound back to a natural undeflected position so that the hooks catch on the underside of the top wall  71  of the latch bolt  70  to fix the button  80  to the latch bolt  70 . The opening  78  may take many different forms including, but not limited to, a circular opening, a rectangle, an oval, a figure-8, a polygon, etc, and must merely accommodate the hooked extensions  86  and  87 . In a preferred embodiment the opening is square shaped. 
         [0040]    A spring  90  may be used to bias the latch bolt  70  to normally occupy an extended position, such that the nose  76  of the latch bolt  70  protrudes from an opening in the housing  50 . Spring  90  may be a tension spring or a compression spring, depending on its placement relative to latch bolt  70  and housing  50 . In a preferred embodiment, spring  90  is a compression spring. The travel of the latch bolt  70  relative to housing  50  may be limited in a number of ways, but in a preferred embodiment, the housing  50  may have a stop  57 , which may be used to contact a flange  88  that protrudes down from the underside of button  80  and prevent the compression spring from causing excessive travel and disengagement of the latch bolt  70  from the housing  50 . 
         [0041]    The latch  40  may have a housing  50  which may be comprised of a first side wall  51 , and a second side wall  52 , where at least a portion of each side wall is connected to top plate  55 . Although it is not required, a back wall  53  may also connect to at least a portion of the first and second side walls, and may also connect to the top plate  55 . Similarly, opposite the top plate may be a bottom wall connecting to at least a portion of the first and second side walls to provide an enclosure within which a latch bolt  70  may translate. However, instead of a bottom wall creating an enclosure, one of several alternative methods to slidably retain the latch bolt may be used, including, but not limited to, rectangular wings protruding from the side of the latch bolt which may be slidably retained by a slot in the first and second housing sidewalls, a lip extending from the first and second side walls, etc. 
         [0042]    An opening  30  in the top rail  27  of the lower window  22  exposes a top wall of the rail and creates an outer flange  31  of the rail opening and an inner flange  32  of the rail opening, and also creates a side flange  33  of the stile  24  ( FIG. 1 ). 
         [0043]    The top plate  55  may overhang beyond the first side wall  51  and second side wall  52 , as well as the back wall  53  if such a back wall is provided, so that upon installation of latch  40  into opening  30  in the top rail  27 , the overhanging portion would positively retain the latch  40  on the top rail  27 , and prevent the latch from dropping down into the hallow area of the rail. 
         [0044]    The second side wall  52 , may have a protrusion  63  extending outward from the wall so that when the latch  40  is inserted into the rail slot  30  of the window  22 , the inside flange  32  (or the outside flange  33 ) may be trapped between the top plate  55  and the protrusion  63 . Also, where a back wall  53  is incorporated into the housing  50 , a similar protrusion  62  on back wall  53  may cooperate with the housing top plate  55  to trap the wall of the top rail at the point where the inside flange  32  and outside flange  33  meet. The protrusion  62  may, for example, have a rectangular cross-sectional shape and a length running along second side wall  52 , as shown in  FIGS. 5 and 6 , but could alternatively comprise other shapes and still be functional. Similarly, protrusion  63  may have a rectangular cross-section and run along a flat or a curved back wall  53 . One possible alternative protrusion  93  may have curved surfaces forming peaks and valleys, as shown in  FIG. 7 . 
         [0045]    The first side wall  51  could, in a conventional approach, have a fixed protrusion similar to protrusion  63  on the second side wall, in order to contact the underside of the top plate and cooperate in retaining the latch  40  in the window slot  30 . However, to successfully counter severe deformations accompanying high wind loading, first side wall  51 , in a preferred embodiment, may have flexibly attached to it a cantilevered member  64  which may have a protrusion  67  extending therefrom. Protrusion  67  may also have a rectangular cross-sectional shape and a length running along the cantilevered member, and may also alternatively comprise other shapes and still be functional. 
         [0046]    In a preferred embodiment of the invention (see  FIG. 2 ), a protrusion  67  extends from a wall of the cantilevered member  64 , creating a lower portion  65  and an upper portion  66  of the wall of the cantilevered member. With the latch installed in a pivotable window, where the window experiences severe deformation due to high wind loading, such as shown in  FIG. 9 , the top area  68  of the protrusion  67  and the upper portion  66  of the cantilevered member  64  will, as a result of biasing, maintain contact with the wall ( 31  or  32 ) of the top rail. 
         [0047]    A cantilevered member  64  may extend only from first side wall  51 , or alternatively cantilevered members may extend from both side walls  51  and  52 , or it may extend from one or more locations of bottom wall  54 . Where such a cantilevered member  64  extends from the housing  50 , it may be configured to have its free end extend a distance beyond the edge of the top plate  55 . Also, as the cantilevered member  64  is flexible attached to the housing  50 , it may be possible to deflect the cantilevered member  64  or members inward to be flush against the respective housing wall. This inwardly deflected position may aid in installing the latch endwise into opening  30  of the lower window  22 , where the opening  30  periphery matches the end profile of the latch, such that the rectangular protrusion  67  may pass through a matching keyway and then be free to expand outward to contact outer flange  31  or inner flange  32  of opening  30 . This inward flexibility of the cantilevered member  64  may even be such that it permits the latch to be installed vertically by dropping it down into the opening  30 , rather than through an endwise installation. A drop down installation as described would eliminate the need for a keyed feature in the portion of opening  30  formed in the stile ( 32  and  33 ) of the window  22 . The configuration for this drop down installation may have a cantilevered member  64  that deflects inward, possibly into an opening or a recess in the housing, but to an extent where such deflection positions the protrusion  67  so as to be clear of the flange ( 31  or  32 ) of the top rail  27  as the latch drops through opening  30 , whereupon the cantilevered member biases outward and contacts the flange. 
         [0048]    The cantilevered member may be a separate wall that is hinged to the side or bottom wall; may be attached—mechanically fastened or bonded or the like—to the side wall or to the bottom wall utilizing a flexible connection at the vertex  91 ; or the cantilevered member may alternatively be an integral portion of the side or bottom wall but with a flexible connection at the vertex  91 . The cantilevered member may generally be free at three sides—the top, the bottom, and the protruding edge, and may be connected to the housing on a fourth side. 
         [0049]    In a preferred embodiment, the cantilevered member  64  is integral to side wall  51 , but normally extends away from side wall  51  at an angle. The connection of the cantilevered member  64  at vertex  91 , in addition to being flexible, may be resilient in nature so as to accomplish biasing, whereby applying a force to deflect the cantilevered member towards the side wall so as to parallel the side wall  51 , creates stored elastic strain energy in the resilient connection. This stored elastic strain energy seeks to return the cantilevered member to its angular position once the force has been removed. This method of biasing may be utilized whether the cantilevered member  64  is integral to the side wall  51 , or if is attached to the side wall. 
         [0050]    As an alternative to having the flexible connection being resilient in nature, a spring means may be utilized to bias either the integral or the attached cantilevered member  64 . Such a spring means may include, but is not limited to, a compression spring, a torsion spring, etc., which may bias the cantilevered member away from the side wall  51 . Where a hinged connection is used to attach a separate wall segment to the housing to serve as a cantilevered member, a spring means may necessarily be used for biasing. During installation of the latch into an opening in the window stile  24  and top rail  27  of the sash window  22 , it may be necessary to manually deflect the cantilevered member  64  into a position parallel to the side wall to prevent the cantilevered member from catching or hanging up on the stile. 
         [0051]    Cantilevered member  64  may also be positioned on the side wall such that the vertex  91  is near back wall  53 , and may have a length equal to the length of the housing, to accommodate severe deformations and still maintain positive contact with the wall of the top rail. Similarly, the first and second side walls  51  and  52 , although shown as having a very shallow depth in a preferred embodiment in  FIG. 2 , may actually extend to a greater depth, and may thus be capable of supporting a cantilevered member having a substantial vertical dimension. Also, although not shown in the figure, an embodiment could include having a pair of cantilevered members extending from each side of the latch, whereby a first cantilevered member could maintain contact with outer flange  31  of the top rail and a second cantilevered member could maintain contact with inner flange  32  of the top rail. 
         [0052]    Another possible embodiment may include a plurality of cantilevered members  64  on each side wall ( 51  and  52 ), or on each side of the bottom wall  54 . It should be noted that for any of these possible embodiments, the cantilevered member  64  may have a vertex  91  and orientation such that the cantilevered member  64  angles away from the housing, with the displaced end of the cantilevered member  64  disposed towards the interior of the window  22 . Alternatively, as in a preferred embodiment, the vertex  91  and orientation of the cantilevered member  64  may be such that the cantilevered member  64  angles away from the housing, with the displaced end of the cantilevered member  64  disposed towards the stile  24  of the window  22 . 
         [0053]    It should be apparent from basic geometry that for a given angular deflection of cantilevered member  64 , that the greater the length of the cantilevered member, the greater the distance its end would be positioned away from the housing  50  side wall, and thus be capable of accommodating greater window deformations caused by wind loading, as the member would still be capable of maintaining contact with the wall of the top rail to support the latch. 
         [0054]    Since the cantilevered member  64  would be constructed to normally extend away from the housing  50  at an angle, which would not be ideal for shipping of the product and could lead to damage to the cantilevered member, the lower portion  65  of the cantilevered member  64  may further comprise a small protrusion  67 . Protrusion  67  of the cantilevered member  64  may, with the cantilevered member pushed flush against the housing  50  side wall, fit into an opening  61  in the housing  50  to prevent the cantilevered member from deflecting outward until the protrusion  67  of the cantilevered member is deliberately disengaged, at which point the cantilevered member may swing into its angled position for installation into a slotted opening  30  of a tiltable sash window  10 . To assist in fitting the protrusion  67  of the cantilevered member  64  into the opening  61 , the lower portion  65  of the cantilevered member may have some slight curvature, as seen in  FIG. 2 . 
         [0055]    To complete endwise installation of the latch  40  through an opening  30  in the stile  24 , a retaining tab  59  may be formed on bottom wall  54  of housing  50 . The retaining tab  59  may protrude down away from the bottom wall  54 , so that once installed, it would contact side flange  33  of the stile  24 , to prevent the latch  40  from working its way out of the slotted opening  30 . To assist in installing the latch  40 , the retaining tab  59  and even the entire bottom wall  54  may be constructed of resilient material. As an alternative, there may be a gap  58  in the bottom wall  54  around retaining tab  59 , which would permit some flexibility of the retaining tab  59  and allow it to be deflected inward as the latch were slid into the slotted opening  30 . 
         [0056]    Other modifications, substitutions, omissions and changes may be made in the design, size, materials used or proportions, operating conditions, assembly sequence, or arrangement or positioning of elements and members of the preferred embodiment without departing from the spirit of this invention as described in the following claims.

Summary:
A latch is provided for use on a pivotable sash window of a single-hung or double-hung sash window assembly to releasably secure the window to the master frame. The latch comprises a latch-bolt slidably mounted within, and biased relative to a housing. The housing is adapted to be installed into the top rail of the sash window through an opening in the stile and top rail, which has a periphery contoured to match the housing end profile. The latch bolt, while maintaining an aesthetically appealing external appearance, is configured to incorporate a cantilevered member which only becomes visible when biased to an angled position where it maintains engagement of the latch housing with the edge of the top wall of the rail during window deformation resulting from high wind loading. The cantilevered member ensures integrity of the latch installation under high wind load conditions typically experienced during extreme weather phenomena.