Patent Publication Number: US-6983963-B2

Title: Forced entry resistance device for sash lock

Description:
RELATED APPLICATIONS 
   This application claims the benefit of application Ser. No. 60/352,701, filed Jan. 29, 2002, which is expressly incorporated by reference herein and made a part hereof. 

   TECHNICAL FIELD 
   This invention relates to sash locks for slidable door or window assemblies. More particularly, it relates to a forced entry resistance device for a sash lock. 
   BACKGROUND OF THE INVENTION 
   Sash locks for double hung window assemblies are commonly known in the art. A double hung window assembly generally has an upper sash window and a lower sash window within a master frame. Typical sash locks draw opposed frame members of the sash windows together and lock the sashes preventing them from sliding within the master frame. 
   One problem associated with typical sash locks is their ability to be manipulated by an intruder from outside the window assembly. That is, sash locks generally include some type of rotatable actuator arm and cam. The actuator is rotatable from an unlocked to a locked position. With some sash locks, the actuator arm or cam may be manipulated from the outside by a skilled intruder using a thin knife, stiff wire, or other diabolical tool of intrusion. 
   The present invention is provided to solve these and other problems. 
   SUMMARY OF THE INVENTION 
   A sash lock for a sash window assembly is provided. The sash window assembly includes an upper sash window and a lower sash window, each of the sash windows mounted within opposed guide rails on a master frame, wherein at least one of the sash windows is slidable within the frame relative to the other sash window. The sash lock of the present invention includes a keeper adapted for mounting on a frame member of one of the sash windows. The keeper includes a keeper surface. The sash lock also includes a locking assembly adapted for mounting on an adjacent member of the other of the sash windows. The locking assembly comprises a housing having an aperture, an actuator arm rotatable between an unlocked position and a locked position and a cam having a cam surface for engaging the keeper surface. A shaft is also provided extending through the aperture and coupling the actuator arm to the cam such that the actuator arm and cam are rotatably mounted to the housing. A tab mounted to the housing is also provided wherein the tab engages the actuator arm to retain the actuator in its locked position. The tab can be deflected to allow the actuator arm to be moved to its unlocked position. 
   In an alternative embodiment the tab is integrally formed with the housing. 
   In an alternative embodiment the tab further comprises a thumb button. 
   Other features and advantages of the invention will be apparent from the remainder of this specification. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a sash window assembly; 
       FIG. 2  is a perspective view of a locking assembly of a prior art sash lock; 
       FIG. 3  is a perspective view of a forced entry resistance device of the present invention; 
       FIG. 4  is a plan view of the resistance device of the present invention; 
       FIG. 5  is a side elevation of the resistance device of the present invention; 
       FIG. 6  is a perspective view of a locking assembly of a sash lock of the present invention utilizing the resistance device; 
       FIG. 7  is a plan view of a locking assembly of the sash lock of the present invention utilizing the resistance device; 
       FIG. 8  is a front elevation of a locking assembly of the sash lock of the present invention utilizing the resistance device; 
       FIG. 9  is a perspective of a locking assembly of the sash lock of the present invention with its actuator arm in the locked position; 
       FIG. 10  is a plan view of the locking assembly of  FIG. 9 ; 
       FIG. 11  is a front elevation of the locking assembly of  FIG. 9 ; 
       FIG. 12  is a perspective of an alternative embodiment of a forced entry resistance device of the present invention; 
       FIG. 13  is a top view of the resistance device of  FIG. 12 ; 
       FIG. 14  is a front elevation of the resistance device of  FIG. 12 ; 
       FIG. 15  is a perspective of a locking assembly of the sash lock including the alternative embodiment of a resistance device of the present invention, with its actuator arm in the locked position; and 
       FIG. 16  is a perspective view of a sash lock housing showing an alternative embodiment of a forced entry resistance device according to the present invention. 
   

   DETAILED DESCRIPTION 
   While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated. 
   A sash lock  10  for a sash window assembly  12  is illustrated in the FIGURES. As generally shown in  FIG. 1 , the sash window assembly  12  includes an upper sash window  14  and a lower sash window  16 . Each of the sash windows  14 ,  16  is mounted within opposed guide rails  18  on a master frame  20 . At least one of the sash windows  14 ,  16  is slidable within the frame  20  relative to the other of the sash windows  14 ,  16 . Each sash window  14 ,  16  has a pair of horizontal frame members  21 . 
   The sash lock  10  includes a keeper  22  and a locking assembly  24 . The keeper  22  includes a keeper surface (not shown) and a pair of mount holes (not shown) for mounting the keeper  22  to one of the frame members  21 , as described more fully below. 
   The locking assembly  24  of the present invention is shown in  FIG. 6  and includes a housing  30 , an actuator arm  32 , a cam  34  ( FIG. 10 ) and a forced entry resistance device or anti-rotation device  36 . A locking assembly  24  of the prior art without the anti-rotation device  36 , is shown in  FIG. 2 . The housing  30  includes a pair of mount holes  28  and an aperture  33 . The cam  34  includes a cam surface  40  ( FIG. 10 ) for engaging the keeper surface. A shaft  35  connects the cam  34  to the actuator arm  32  through the aperture. It is understood that the actuator arm  32  and the shaft  35  can be a single integral member. In this way, the cam  34  and actuator arm  32  are rotatably mounted to the housing  30 . That is, there is no relative movement between the cam  34  and actuator arm  32 , however, the cam  34  and actuator arm  32  together, rotate with respect to the housing  30 . 
   The anti-rotation device  36  ( FIGS. 3–8 ) includes a body  42  having an external tab  44 . The body  42  is adapted for mounting to the housing  30  and includes a mount hole  43  for this purpose. The external tab  44  is generally rectangular in cross section and is resiliently flexible. The external tab  44  includes an inclined surface  45  and an engagement surface  48 . 
   The actuator arm  32  of the locking assembly  24  is rotatable between an unlocked position ( FIG. 6 ) and a locked position as shown in  FIG. 10 . In the unlocked position, the cam  34  is located completely within the housing  30 . In the locked position, the cam  34  has rotated and its cam surface  40  is substantially external to the housing  30  to engage the keeper surface. 
   In the embodiment described, the keeper  22  is mounted to the lower frame member or base  21  of the upper sash window  14  ( FIG. 1 ). The keeper  22  is mounted with a pair of screws or other fasteners extending through the mount holes and secured to the base  21 . Typically, the keeper  22  is mounted near the center of the base  21 . 
   The locking assembly  24  is mounted to the upper frame member of top rail  23  of the lower sash window  16 . It is mounted such that it is immediately adjacent to the keeper  22  when the upper sash window  14  is in its upper most position within the frame  20  and the lower sash window  16  is in its lower most position within the frame  20 . In mounting the locking assembly  24 , a screw or other fastener (not shown) is passed through the mount hole  43  of the body  42  of the anti-rotation device  36 . The screw is then passed through one of the mount holes  28  of the locking assembly  24  and secured to the top rail  23 . (See  FIG. 6 ). Another screw or fastener is then used to secure the housing  30  to the top rail  23  via its other mount hole  28 . In this way, the anti-rotation device  36  is secured to the housing  30  and the housing is secured to the upper stile  21  of the lower sash window  16 . It is not important to which mount hole  28  of the housing  30  the anti-rotation device  36  is secured. It is important that the anti-rotation device  36  is in a position to be immediately adjacent to the actuator arm  32  when the actuator arm  32  is in its locked position. 
   For instance, the locking assembly  24  depicted in the FIGURES is configured such that the actuator arm  32  rotates in a clockwise direction when rotating from the unlocked to the locked position. However, it is understood that the locking assembly  24  may be configured such that its actuator arm  32  rotates in a counter-clockwise direction in moving from the unlocked to the locked position. In this instance, the device  36  would be mounted to the other mounting hole  28  of the housing  30  than shown in the FIGURES. 
   In operation, with the actuator arm  32  in the unlocked position, the upper sash window  14  is raised to its upper most position within the frame  20  and the lower sash window  16  is lowered to its lower most position within the frame  20 . This brings the locking assembly  24  to a position immediately adjacent the keeper  22 .  FIGS. 6–8  show the locking assembly  24  with the actuator arm  32  in the unlocked position. The actuator arm  32  is then rotated towards it locked position. This rotates the cam  34  to a position external to the housing  30  and causes the cam surface  40  to engage the keeper surface, in a manner commonly known to those of ordinary skill in the art. As the actuator arm  32  approaches the locked position, the arm  32  engages the inclined surface  45  of the external tab  44  slightly depressing the tab  44 . Engagement of actuator arm  32  with the inclined surface  45  of the tab  44  depresses the tab  44  into a deflected position (arrow A in  FIGS. 9 and 11 ). While the tab  44  is in the deflected position, the actuator arm  32  is allowed to pass by the tab  44 . Once the actuator arm  32  passes by the tab  44 , the tab  44  resiliently snaps back from its deflected position to the engagement position wherein the engagement surface  48  of the tab  44  confronts the actuator arm  32  to prevent rotation of the arm  32  back to its unlocked position. While in the engagement position, if the actuator arm  32  is rotated towards its unlocked position, the engagement surface  48  will engage the actuator arm  32  preventing rotation.  FIGS. 9–11  show the locking assembly  24  with the actuator arm  32  in the locked position. 
   To rotate the actuator arm  32  back to its unlocked position, the tab  44  must be depressed, such as by a user&#39;s thumb or other finger. This deflects the tab  44  in the direction of arrow A and disengages or moves the engagement surface  48  from the rotational path of the actuator arm  32  and allows rotation of the same. While the tab  44  is depressed to a deflected position, the actuator arm  32  is rotated past the tab  44  to its unlocked position. 
   In an additional embodiment of the invention shown in  FIGS. 12–15 , the anti-rotation device  36  includes a thumb button  50 . The thumb button  50  is connected at one end to an under side of the external tab  44 . Another end of the thumb button  50  is curved and extends away from the housing  30 . The thumb button  50  improves the ease with which a user may depress the tab  44  to allow the actuator arm  32  to be moved from the locked to the unlocked position. 
   Although the invention has been described as being applied to a vertically sliding double hung window, it is understood the invention can equally be applied to horizontally sliding sash window arrangements or any operable sash window that slides within a frame. 
   Additionally, although not shown in the drawings, it will be understood by those of ordinary skill in the art, that the anti-rotation device  36  may be integrally formed with the housing  30  while remaining within the scope of the present invention. (See  FIG. 16 .) Furthermore, it is understood that the resistance or anti-rotation device  36  may be formed from any number of materials of sufficient strength to withstand the forces involved in an attempted rotation of the actuator arm  32  by an intruder, while remaining resiliently flexible enough to allow depression of the external tab  44  by the user. For example, the device  36  may be formed from various metals and alloys thereof as commonly known, providing the required strength and resilience. 
   It is also understood that the resistance device  36  may take other forms. For example, the device may be a spring biased tab, or pop-up button that similarly interferes with the path of rotation of the actuator arm  32  from the locked to the unlocked position. These alternatives remain within the scope of this invention. 
   It can be appreciated that the device  36  of the present invention will prevent simple rotation of the actuator arm  32  without additional manipulation of the device  36 . The device  36 , while not intruder-proof, will provide significant deterrence to forced entry and unwanted manipulation of the sash lock  10  from outside the sash window assembly  12 . It can further be appreciated that as the device  36  is external to the housing  30  of the locking assembly  24 , an embodiment of the device  36  may be adapted for retrofitting to existing sash lock  10  installations currently in use. This purpose and others are served by a simplicity of construction and an external nature of the device  36 , not previously known in the art. 
   While the specific embodiments and various details thereof have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention and the scope of protection is only limited by the following claims.