Patent Publication Number: US-8967684-B2

Title: Self-aligning window sash lock

Description:
RELATED APPLICATION DATA 
     This application claims the benefit of priority of U.S. Provisional Patent Application No. 61/313,905, filed Mar. 15, 2010, entitled “Self-Aligning Window Sash Lock,” which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to the field of double-hung window hardware. In particular, the present invention is directed to a self-aligning window sash lock. 
     BACKGROUND 
     Historically, sash locks for double hung windows have served several purposes. The first sash locks served only to prevent the windows from being opened, the traditional function of a lock. The sash lock later evolved to serve two other purposes, to draw the check rails of the upper and lower sashes together tightly, and to a limited extent, force the upper sash in an upwards direction and the lower sash in a downwards direction. Both of these functions serve to make the window more weather-tight. 
     SUMMARY OF THE DISCLOSURE 
     In one implementation, the present disclosure is directed to a sash lock for a window installation having an upper sash and a lower sash, wherein 1) the upper sash includes a window pane and a lower check rail having a first upper side, 2) the lower sash includes an upper check rail having a second upper side, and 3) at least one of the upper and lower sashes is slidable relative to the other of the upper and lower sashes in a vertical plane parallel to the window pane. The sash lock includes: a latch configured to be secured to the upper check rail of the lower sash on the second upper side in a manner that the latch is pivotable horizontally, the latch including a draw member having a catch-contacting surface that is arcuate in a horizontal plane; and a catch configured to be fixedly secured to the lower check rail of the upper sash on the first upper side, the latch including a draw-member-contacting surface for slidingly receiving the catch-contacting surface of the latch, wherein, when the sash lock is installed in the window installation, the draw-member-contacting surface: is concave in a vertical plane perpendicular to the window pane and in a direction perpendicularly away from the window pane; has an upper portion for contacting the catch-contacting surface of the draw member so as to generate a first point-contact force having: a vertical component for drawing the upper and lower check rails together; and a horizontal component for vertically aligning the upper and lower check rails with one another; and has a lower portion for contacting the catch-contacting surface of the draw member so as to generate a second point-contact force having: a vertical component for drawing the upper and lower check rails together; and a horizontal component for vertically aligning the upper and lower check rails with one another. 
     In another implementation, the present disclosure is directed to a window installation. The window installation includes: an upper sash that includes a window pane and a lower check rail having a first upper side; a lower sash that includes an upper check rail having a second upper side, wherein: at least one of the upper and lower sashes is slidable relative to the other of the upper and lower sashes in a vertical plane parallel to the window pane; and the upper and lower sashes have a desired vertical alignment relationship when properly locked together; and a sash lock that includes: a latch secured to the upper check rail of the lower sash on the second upper side in a manner that the latch is pivotable horizontally, the latch including a draw member having a catch-contacting surface that is arcuate in a horizontal plane; and a catch fixedly secured to the lower check rail of the upper sash on the first upper side, the latch including a draw-member-contacting surface for slidingly receiving the catch-contacting surface of the latch, wherein the draw-member-contacting surface: is concave in a vertical plane perpendicular to the window pane and in a direction perpendicularly away from the window pane; has an upper portion for contacting the catch-contacting surface of the draw member so as to generate a first point-contact force having: a vertical component for drawing the upper and lower check rails together; and a horizontal component for vertically aligning the upper and lower check rails with one another; has a lower portion for contacting the catch-contacting surface of the draw member so as to generate a second point-contact force having: a vertical component for drawing the upper and lower check rails together; and a horizontal component for vertically aligning the upper and lower check rails with one another; and has a nadir between the upper and lower portions, wherein, when the upper and lower sashes are properly locked together by the sash lock and are in the desired vertical alignment, the draw member is located substantially at the nadir. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For the purpose of illustrating the invention, the drawings show aspects of one or more embodiments of the invention. However, it should be understood that the present invention is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein: 
         FIG. 1A  is a horizontal cross-sectional view of a window installation that includes a sash lock made in accordance with the present invention, showing the sash lock in a fully locked configuration; 
         FIG. 1B  is a cross-sectional view as taken along line  1 B- 1 B of  FIG. 1A ; 
         FIG. 2A  is an elevational view of the catch of the sash lock of  FIGS. 1A-B ; 
         FIG. 2B  is a cross-sectional view as taken along line  2 B- 2 B of  FIG. 2A ; 
         FIG. 3A  is a vertical cross-sectional view of the window installation of  FIGS. 1A-B  showing the upper and lower sashes vertically misaligned such that the upper surface of the lower check rail of the upper sash is higher than the upper surface of the upper check rail of the lower sash; 
         FIG. 3B  is a cross-sectional view as taken along line  3 B- 3 B of  FIG. 3A ; 
         FIG. 4A  is a vertical cross-sectional view of the window installation of  FIGS. 1A-B  showing the upper and lower sashes vertically misaligned such that the upper surface of the lower check rail of the upper sash is lower than the upper surface of the upper check rail of the lower sash; 
         FIG. 4B  is a cross-sectional view as taken along line  4 B- 4 B of  FIG. 4A ; 
         FIG. 5A  is an enlarged vertical cross-sectional view of another embodiment of the catch of an alternative sash lock made in accordance with the present invention; and 
         FIG. 5B  is an enlarged elevational view of the catch of  FIG. 5A . 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings,  FIGS. 1A-B  illustrate a window installation  100  that includes an upper sash  104  and a lower sash  108 , one, the other, or both of which are vertically movable in the manner of conventional single- and double-hung windows. Window installation  100  also includes a sash lock  112  that has features that not only effectively draws upper and lower sashes  104 ,  108  together at their meeting parts, but also acts to precisely vertically align the upper and lower sashes, regardless of the direction of the initial vertical misalignment. These and other features of sash lock  112  are described below in detail. However, before presenting those details, a few contextual details of components of window installation  100  other than sash lock  112  are first described. It is noted that as used herein and in the appended claims, the terms “upper,” “lower,” “vertical,” “horizontal” and like terms, express conventional positional relationships and orientations relative to an installed sash-over-sash window system. 
     Upper sash  104  includes a lower check rail  116  having an upper surface  116 A, and lower sash  108  includes an upper check rail  120  having an upper surface  120 A. As in conventional single- and double-hung window installations, when upper and lower sashes  104 ,  108  are in their proper closed positions lower check rail  116  and upper check rail  120  meet with one another such that their respective upper surfaces  116 A,  120 A are flush with one another. Also as in conventional single- and double-hung window installations, window installation  100  includes other parts, such as window panes  124 ,  128 , side and head jambs (not shown) and sill, among other things. As those skilled in the art will readily appreciate, lower and upper check rails  116 ,  120  can be made from any one or more materials. For example, each rail  116 ,  120  may be made from wood, plastic or metal covered wood, a metal extrusion, a plastic extrusion or plastic covered metal, among others. Those skilled in the art will also readily appreciate that window panes  124 ,  128  can be made of any suitable sheet material, such as glass (coated and uncoated) or plastic and may have any number of layers that can include one or more reflective layers, one or more filtering layers, etc. Upper and lower sashes  104 ,  108  can be of any age. That is, sash lock  112  can be used in virtually any new or retrofit installation, although various parts of the sash lock may need to be modified dimensionally or otherwise to accommodate special circumstances that may arise in some installations. 
     Sash lock  112  includes a catch  132  fixedly secured to lower check rail  116  of upper sash  104 . In this example, catch  132  is fixedly attached to a base  136  that allows the catch to be readily secured to the lower check rail using suitable fasteners, such as screws  140  shown. As best seen in  FIG. 2A-B , in this embodiment a catch-upper-end support  144  is included to provide additional support to upper end  132 A of catch  132 . Support  144  includes a horizontal member  144 A and two posts  144 B-C joining the horizontal member to base  136 . In the embodiment shown, catch  132 , base  136  and catch-upper-end support  144  are monolithic and formed in a single casting. In other embodiments, one or more of these components can be formed separately from the other(s) and then attached to one another using any suitable attachment means/method(s). In one example, catch  132 , base  136  and catch-upper-end support  144  are made of brass, but these parts can, of course, be made of other suitable materials. It is noted that while this embodiment includes a base  136 , other embodiments can include some other means for securing catch  132  to lower check rail  116 . 
     Referring particularly to FIGS.  1 B and  2 A-B, it is seen that catch  132  has an arcuate contact surface  132 B, as viewed in a vertical plane such as the plane of the section of  FIG. 1B , that is concave in a direction away from window pane  124 . As described in more detail below, this shape and concavity give sash lock  112  its ability to vertically align upper and lower sashes  104 ,  108  with one another upon actuating the sash lock to lock the sashes together. The curvature of contact surface  132 B can be circular, spiral, elliptical, etc. If circular, the radius of curvature can be any suitable to achieve the vertical alignment functionality. For example, in some embodiments the radius of curvature can be about 2 inches (about 5 cm) or less, and more preferably, about 1 inch (about 2.5 cm) or less.  FIG. 2B  shows that contact surface  132 B can also be contoured in a generally horizontal direction to enhance operability of sash lock  112 . 
     Referring again to  FIGS. 1A-B , in addition to catch  132  on lower check rail  116  of upper sash  104 , sash lock  112  also includes a latch  148  pivotably secured to upper check rail  120  of lower sash  108 . Latch  148  includes a handle lever  152  and a draw member  156  that has a contact surface  156 A that contacts contact surface  132 B of catch  132  during use of sash lock  112  and generally defines a spiral shape configured to draw the catch and lower check rail  116  toward upper check rail  120  as a user pivots, in this example, latch  148  in a clockwise direction so as to fully engage draw member  156  with the catch. When fully engaged, sash lock  112  firmly holds lower and upper check rails  116 ,  120  into engagement with one another, including any weather stripping/sealing that may be located therebetween. As seen in  FIG. 1B , draw member  156  engages contact surface  132 B of catch  132  at the nadir  132 C of the concavity of that surface when lower and upper check rails  116 ,  120  are properly vertically aligned with one another. This fact, in combination with the concavity of contact surface  132 B of catch  132  and the configuration of draw member  156 , act together to provide sash lock  112  with the ability to vertically align lower and upper check rails  116 ,  120  with one another so that they end up in their proper vertical alignment when the sash lock is fully engaged. This is described below in further detail. 
     In the embodiment shown in  FIGS. 1A-B , latch  148  is pivotably connected to a base  160  to form a latch assembly  164 . Base  160  allows latch assembly  164  to be fixedly attached to upper check rail  120 , in this example using a pair of screws. While this arrangement is shown, those skilled in the art will readily appreciate that in other embodiments, pivotable latch  148  could be attached to a different style of base or other structure for securing the latch to a corresponding upper check rail. For example, such an alternative base may be integrally formed with the check rail. In addition, in some embodiments base  160  may be eliminated altogether. Those skilled in the art will readily understand the many variations that are possible within the scope of the present invention. The illustrated embodiment of latch  148  includes a grip  168  that a user can grasp with his/her fingers to pivot the latch during use. 
     In this embodiment, latch  148  is pivotably attached to base  160  using a pin arrangement in which a pin  172  is secured to the base and the latch is effectively clamped between a head  172 A on the pin and a low-friction bearing  176  that is sandwiched between the latch and the base. A retainer  180  secures pin  172  to base  160 . As those skilled in the art will readily understand, there are other ways of pivotably attaching latch  148  to base  160  or other structure. In the example shown, latch  148 , grip  168 , base  160  and pin  172  are separate components and are all made of brass, retainer  180  is made of steel and friction bearing  176  is made of nylon. In other embodiments these parts can be made of any one or more suitable materials, which may be selected not only for their mechanical suitability, but also for their aesthetic qualities. 
     Having described the structure of sash lock  112 , its operation is now described. Referring first to  FIGS. 3A-B , these figures illustrate a scenario in which sash lock  112  is being used when upper surface  120 A of upper check rail  120  of lower sash  108  is initially higher than upper surface  116 A of lower check rail  116  of upper sash  104  and there is a loose fit between the check rails, as illustrated by gap  300 . In this case, when a user (not shown) pivots latch  148  counterclockwise, as illustrated by arrow  304  ( FIG. 3B ), draw member  156  initially contacts contact surface  132 B of catch  132  near upper end  132 A of the catch. Then, as the user continues to pivot latch  148  clockwise, spiral contact surface  156 A on draw member  156  acts on catch  132  to impart a contact force  308  ( FIG. 3A ) that is normal to contact surface  132 B on the catch. Because contact surface  132 B is sloped as shown, contact force  308  has not only a horizontal component  308 H, which acts to draw lower and upper check rails  116 ,  120  together (as indicated by arrows  312  (FIG.  3 A)), but also a vertical component  308 V, which acts to cause upper sash  104  to move upward (as indicated by arrow  316  ( FIG. 3A )) and/or cause lower sash  108  to move downward (as indicated by arrow  320 ). As those skilled in the art should be able to readily envision, as the user continues to pivot latch  148  clockwise, the movement of upper and lower sashes  104 ,  108  continues until draw member  156  is at nadir  132 C of contact surface  132 B of catch  132 . At that point, which is best shown in  FIG. 1B , upper surfaces  116 A,  120 A of lower and upper check rails  116 ,  120 , respectively, are flush with one another. In addition, if latch  148  is pivoted to its fully engaged position, as illustrated in  FIG. 1A , gap  300  ( FIG. 3A ) will be at a minimum. 
     Referring now to  FIGS. 4A-B , these figures illustrate a scenario in which sash lock  112  is being used when upper surface  120 A of upper check rail  120  of lower sash  108  is initially lower than upper surface  116 A of lower check rail  116  of upper sash  104  and there is a loose fit between the check rails, as illustrated by gap  400 . In this case, when a user (not shown) pivots latch  148  counterclockwise, as illustrated by arrow  404  ( FIG. 4B ), draw member  156  initially contacts contact surface  132 B of catch  132  near lower end  132 D of the catch. Then, as the user continues to pivot latch  148  clockwise, spiral contact surface  156 A on draw member  156  acts on catch  132  to impart a contact force  408  ( FIG. 4A ) that is normal to contact surface  132 B on the catch. Because contact surface  132 B is sloped as shown, contact force  408  has not only a horizontal component  408 H, which acts to draw lower and upper check rails  116 ,  120  together (as indicated by arrows  412  (FIG.  4 A)), but also a vertical component  408 V, which acts to cause upper sash  104  to move downward (as indicated by arrow  416 ) and/or cause lower sash  108  to move upward (as indicated by arrow  420 ). As those skilled in the art should be able to readily envision, as the user continues to pivot latch  148  clockwise the movement of upper and lower sashes  104 ,  108  continues until draw member  156  is at nadir  132 C of contact surface  132 B of catch  132 . At that point, which is best shown in  FIG. 1B , upper surfaces  116 A,  120 A of lower and upper check rails  116 ,  120 , respectively, are flush with one another. In addition, if latch  148  is pivoted to its fully engaged position, as illustrated in  FIG. 1A , gap  400  ( FIG. 4A ) will be at a minimum. 
       FIGS. 5A-B  illustrate an example of an alternative catch  500  that can be used in a sash lock, such as sash lock  112  of  FIGS. 1A-B  to provide the dual vertical alignment functionality just described relative to catch  132 . Like catch  132 , catch  500  of  FIGS. 5A-B  has a contact surface  500 A that, when viewed in a vertical plane, is concave in a direction away from the window pane (not shown) of the upper sash (not shown) to which catch  500  is attached. However, in this embodiment, contact surface  500 A is defined by two substantially straight portions, i.e., an upper portion  500 B and a lower portion  500 C, that converge at a vertex  500 D. In this embodiment, vertex  500 D is equivalent to nadir  132 C of catch  132  of  FIG. 1B , such that when the upper surfaces of the lower and upper check rails (not shown) are flush with one another and the sash lock is fully engaged, the draw member  504  is located substantially at vertex  500 D ( FIG. 5A ). Also similar to catch  132  of  FIG. 1A , upper portion  500 B of contact surface  500 A acts to bring the lower and upper check rails into vertical alignment with one another when the upper surface of the upper check rail of the lower sash is initially higher than the upper surface of the lower check rail of the upper sash. Similarly, lower portion  500 C of contact surface  500 A acts to bring the lower and upper check rails into vertical alignment with one another when the upper surface of the upper check rail of the lower sash is initially lower than the upper surface of the lower check rail of the upper sash. These alignment actions similarly occur as a result of the respective contact forces  508 ,  512  having vertical components  508 V,  512 V in addition to horizontal components  508 H,  512 H. As an example of the slope of upper and lower portions  500 B,  500 C, each of these portions preferably, but not necessarily, has a vertical angle, V, of about 15° or more. 
     Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various changes, omissions and additions may be made to that which is specifically disclosed herein without departing from the spirit and scope of the present invention.