Abstract:
A locking system for sliding windows. The system includes a lock assembly that uses plastic components designed for enhanced strength. The system can be readily aligned in manufacturing through the use prefabricated aspects on the lock rail of a sash that complement features on the lock assembly. The system can also be assembled using a single mounting fastener for ease of assembly in manufacturing.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/640,412, entitled LOCK DEVICE FOR SLIDING WINDOWS, filed Apr. 30, 2012, said application hereby fully incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The disclosed invention relates generally to the windows. More specifically, the invention relates locking systems for sliding windows. 
       BACKGROUND OF THE INVENTION 
       [0003]    Window manufacturers typically use locking devices on the sash meeting rails of sliding window assemblies to provide environmental control and security, and to prevent unintentional opening of the windows. Plastic or composite locks are preferred for reasons of aesthetics, cost reduction, and corrosion resistance. However, plastic locks tend to be weaker than metal locks and typically do not perform as well as metallic locks under loading conditions. Manufacturers also desire to minimize fasteners for faster and easier assembly of the locks to the window, as well as for aesthetic reasons. 
         [0004]    What is needed in the industry is a window locking device primarily of plastic or composite components with enhanced performance characteristics and ease of assembly. 
       SUMMARY OF THE INVENTION 
       [0005]    Various embodiments of the invention provide a window lock having plastic components with improved load performance, that is easily assembled in the manufacturing environment, and that is adaptable to a variety of window applications and in a variety of aesthetic designs. The assembly requires only a few components and is readily assembled in a top-down fashion for augmentation in an automated assembly environment. 
         [0006]    U.S. Pat. No. 3,645,573 to Strang (“Strang”) discloses the use of single screw that passes through a lock element and base, the base having spurs positioned laterally from the screw for penetrating the wood surface of a sash to prevent the assembly from rotating during installation of the screw and to resist torsion during operation. The device of Strang is lacking in several respects. The spurs are inoperable with certain sash materials such as metals and harder polymers. Even where a wooden sash is utilized, the diminutive size of the spurs that are necessary for penetration of the wood creates high stress in the penetration region during operating of the lock, causing the spurs to tear away with time. The spurs also do little to resist the bending load placed on the assembly, meaning that the screw must bear the majority of the bending load. In addition, the spurs do not assist in the initial translational and rotational alignment of the assembly. 
         [0007]    In various embodiments of the invention, a single mounting fastener is used in the center pivot of a handle and a rotating cam. Certain embodiments include a housing, also secured in place by the mounting fastener, that includes a tab feature that is inserted into prefabricated elongate slot on the lock rail of the sash, and/or one or more boss features that are inserted into a prefabricated hole or holes. The tab feature is easy to insert into the lock rail and the lock is held down securely due to the slight spring bias created by the tab and the mounting fastener. The tab feature can provide relief of the fastener against bending under load conditions, and can also assist in securing the lock assembly tightly against the lock rail. The boss features are of large diameter to provide load distribution and reduced stresses on the boss features as well as on the lock rail. The boss features are also positioned at the forward corners of the housing to provide the greatest distance possible between the boss features and the rotation axis of the lock assembly, thereby minimizing shear load on the boss features under the torsional load. 
         [0008]    Mounting of the lock assembly is streamlined by the tab feature and boss feature(s) of the housing and by the need for only a single mounting fastener to secure the lock assembly to the lock rail of the sash. Actuation of the mounting fastener also acts to finally and permanently secure the rotating cam to the handle. 
         [0009]    In an embodiment, a lock device for a sliding window includes a lock housing having a peripheral wall defining a recess. A sweep cam is received in the recess of the lock housing and selectively rotatable relative to the housing with a handle. The lock device further includes a fastener extending through the handle, sweep cam, and housing to secure the lock device to a sash of the sliding window, wherein the housing presents at least one downward projection on the peripheral wall of the housing for engaging in a corresponding recess in the sash of the window. 
         [0010]    In an embodiment, the at least one downward projection comprises a tab receivable in a slot in the window sash. In another embodiment, the at least one downward projection comprises a boss. In a further embodiment, the housing presents three downward projections on the peripheral wall of the housing. The three downward projections can comprise a tab and two bosses. 
         [0011]    In a further embodiment, a sliding window system includes a frame, a first sash slidably disposed in the frame, and a second sash slidably disposed in the frame, the first sash defining at least one recess in a rail of the sash. The system further includes a lock device including a lock housing having a peripheral wall defining a recess, a sweep cam received in the recess of the lock housing and selectively rotatable relative to the housing with a handle, and a fastener extending through the handle, sweep cam, and housing to secure the lock device to the first sash, wherein the housing presents at least one downward projection on the peripheral wall of the housing, the at least one downward projection engaged in the at least one recess in the rail of the first sash. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The embodiments of the present invention may be more completely understood in consideration of the following detailed description of various embodiments in connection with the accompanying drawings, in which: 
           [0013]      FIG. 1  is a cutaway view of a locking system in an embodiment of the invention; 
           [0014]      FIG. 1   a  is an isometric view of a window according to an embodiment of the invention; 
           [0015]      FIGS. 2 and 3  are a perspective views of a lock assembly in an embodiment of the invention; 
           [0016]      FIG. 4  is a perspective view of a handle of the lock assembly of  FIG. 2  in an embodiment of the invention; 
           [0017]      FIGS. 5 and 6  are a perspective views of a housing of the lock assembly of  FIG. 2  in an embodiment of the invention; 
           [0018]      FIGS. 7 and 8  are a perspective views of a rotating cam of the lock assembly of  FIG. 2  in an embodiment of the invention; 
           [0019]      FIG. 9  is a perspective view of a bushing of the lock assembly of  FIG. 2  in an embodiment of the invention; 
           [0020]      FIG. 10  is a perspective view of a keeper of the lock system of  FIG. 1  in an embodiment of the invention; 
           [0021]      FIG. 11  is an exploded view of the lock assembly of  FIG. 2 ; 
           [0022]      FIGS. 12 and 13  are sectional views of the lock assembly of  FIG. 2  during assembly; 
           [0023]      FIG. 14  is a partial plan view of an inner sash and an outer sash with prefabricated aspects in an embodiment of the invention; and 
           [0024]      FIG. 15  is a sectional view of the lock system of  FIG. 1 . 
       
    
    
       [0025]    While the present invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the present invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention. 
       DETAILED DESCRIPTION 
       [0026]    In  FIG. 1   a  there is depicted a double-hung sliding window  28  with a lock assembly  30  according to an embodiment of the invention. Window  28  generally includes inner sash  36  and outer sash  44  slidably disposed in frame  31  as is generally known in the art. 
         [0027]    Referring to  FIG. 1 , a locking system  30  for a sliding window is depicted in an embodiment of the invention. The locking system  30  includes a lock assembly  32  coupled to a lock rail  34  of the inner sash  36  of a window. The lock assembly  32  is generally aligned with a keeper  38  that is mounted on an interior side  42  of an outer sash  44  of the window. 
         [0028]    Referring to  FIGS. 2 through 10 , the lock assembly  32  and its individual components are depicted in an embodiment of the invention. In the depicted embodiment, the lock assembly  32  comprises a housing  46 , a rotating cam  48 , a handle  52 , and a bushing  54 . The lock assembly  32  is used in conjunction with a mounting fastener  56 . 
         [0029]    In various embodiments, the housing  46  includes a mounting face  58  that defines a mounting plane. The housing  46  can also include at least one tab feature  62  and one or more boss features  64  that extend through the mounting plane. The tab feature  62  can include a flared end  66  as well as vertical gussets  68  that enhance the strength and stiffness of the tab feature  62 . Any number of boss feature(s)  64  can be utilized, or no boss features at all. Alternatively, snap features (not depicted) that snap into corresponding holes in the lock rail  34  can be used instead of or in addition to the boss features  64 . The housing  46  can also include stop bosses  70  that extend from an interior surface  71  of the housing  46 . 
         [0030]    The rotating cam  48  can include a first face  72  that is substantially planar and a second face  74  opposite the first surface, with an outer ridge  76  that extends parallel to a rotation axis  78  from the second face  74 . The outer ridge  76  can include a ramp portion  82  and a plateau portion  84 . In one embodiment, the rotating cam  48  defines a through-passage  86  about the rotation axis  78  having a circular opening  88  on the first face  72  that is concentric with a square or otherwise polygonal opening  92  on the second face  74 . The square or polygonal opening  92  defines a square or polygonal recess  94  that extends partway through the thickness of the rotating cam  48  to define a registration face  96  that extends radially inward at confluence between the circular and square openings  88  and  92 . The rotating cam  48  can also include a stop feature  98  on the second face  74 . 
         [0031]    The handle  52  includes a lever portion  102  and a hub portion  104 , the hub portion  104  having a distal end  106 . The hub portion  104  comprises a barrel portion  108 , a tenon portion  112  distal to the barrel portion  108 , and a retaining feature or features  114  formed at the distal end  106  of the hub portion  104 . The tenon portion  112  is adapted to fit within the square or polygonal recess  94  of the rotating cam  48 . A pivot passage  116  is defined that passes through the lever portion  102  and hub portion  104 . In one embodiment, the distal end  106  of the hub portion  104  is formed to have an inner diameter  118  that is slightly reduced relative to portions of the pivot passage  116  that pass through the lever portion  102 , barrel portion  108  and tenon portion  112 . 
         [0032]    In one embodiment of the invention, the keeper  38  ( FIG. 10 ) is mounted on the interior side  42  of the outer sash  44  of the window ( FIGS. 1 and 15 ) and is generally aligned with the lock assembly  32 . The keeper  38  can include a frame portion  122  defining an opening  124  and a mounting face  126 . One of the frame members can include a lip portion  128  that extends partially over the opening  124 . The frame can also include a mounting member  132  that defines one or more holes  134  for accommodating fasteners, and gussets  136  for enhanced strength. In one embodiment, the frame includes a rib  138  that projects from the mounting face  126 . 
         [0033]    Referring to  FIGS. 11 through 13 , assembly of the lock assembly  32  is depicted in an embodiment of the invention. In the depicted embodiment, the handle  52  is inserted into the housing  46  and the rotating cam  48  is inserted over the tenon portion  112  of the handle  52 . The rotating cam  48  is pressed onto the tenon portion  112  of the hub portion  104  so that the tenon portion  112  is seated against the registration face  96  of the square or polygonal recess  94  and so that the circular aperture of the rotating cam  48  snaps over the retaining feature or features  114  on the distal portion the hub portion  104 . The bushing  54  is inserted into the opening of the pivot passage  116  on the handle  52  ( FIG. 12 ) and driven through the hub portion  104  to the distal end  106  ( FIG. 13 ). As the bushing  54  passes through the reduced inner diameter  118  of the distal end  106  of the hub portion  104 , the retaining features  114  of the barrel portion  108  are flared radially outward, thereby preventing the retaining feature or features  114  from collapsing inward under load conditions. Accordingly, the rotating cam  48  is positively secured to the handle  52 . 
         [0034]    It is noted that driving the mounting fastener  56  during mounting of the lock assembly  32  to the inner sash  36  can act to deploy the retaining features  114  radially outward as described above. 
         [0035]    Functionally, the various mechanisms described above positively secure the rotating cam  48  to the handle  52 . The tenon portion  112  and square or polygonal recess  94  cause rotational coupling between the handle  52  and the rotating cam  48 . The bushing  54  positively interlocks the retaining features  114  of the barrel portion  108  to the rotating cam  48  to prevent separation of these components along the rotation axis  78 . Accordingly, the lock assembly  32  will not loosen or come apart over time. 
         [0036]    The mounting fastener  56  passes through the housing  46 , handle  52  and rotating cam  48  for fastening the lock assembly  32  to the lock rail  34  and distributes the load on the rotating cam  48  to the lock rail  34 . Alternatively, in place of the mounting fastener  56 , a boss (not depicted) could extend from either the handle  52  or cam  48  or some other separate component into a hole in the lock rail  34  to provide a means to help distribute loading on the rotating cam  48  to the lock rail  34  in a similar fashion. 
         [0037]    The bushing  54  can also provide vertical support for the mounting fastener  56  by carrying the compression force exerted by the mounting fastener  56 , thus enabling the handle  52  and rotating cam  48  to rotate freely. The bushing  54  further isolates the handle  52  from contact with the mounting fastener  56 , so that the actuation motion does not cause wear between the handle  52  and the mounting fastener  56  or otherwise cause loosening of the mounting fastener  56 . 
         [0038]    In operation, the handle  52  is actuated to rotate the rotating cam  48  within the housing  46  between the locked and unlocked positions. As the rotating cam  48  is rotated from the unlocked to the locked position, the outer ridge  76  of the cam  52  passes behind and engages with the lip portion  128  of the keeper  38 , which couples the lock assembly  32  to the keeper  38 . The ramp portion  82  of the outer ridge  76  can function to align the inner and outer sashes  36  and  44  during actuation of the rotating cam  48 . The stop feature  98  of the rotating cam  48  engages with the stop bosses  70  on the housing  46  at both extremes of operation to prevent the rotating cam  48  from rotating past the fully locked and the fully unlocked positions. 
         [0039]    Referring to  FIGS. 14 and 15 , assembly of the lock assembly  32  and lock system  30  are depicted in an embodiment of the invention. Prefabricated aspects  142  of the lock rail  34  of the inner sash  36  are depicted in  FIG. 14 . In this embodiment, the prefabricated aspects  142  include an elongate slot  144  and two alignment holes  146  to receive the tab feature  62  and boss features  64 , respectively. The prefabricated aspects  142  can also include a pre-drilled hole  148  for accepting the fastener  56 . In other embodiments, the prefabricated aspects  142  can include a plurality of alignment slots and any number of alignment holes. 
         [0040]    The lock assembly  32  can be mounted to the lock rail  34  by tipping the housing  46  at approximately a 30 degree angle and aligning the tab feature  62  with the elongate slot  144  in the lock rail  34  and inserting the end of the tab feature  62  into the elongate slot  144  and then rotating the housing  46  downward until the boss features  64  of the housing  46  go into the holes in the lock rail  34  and the bottom of the housing  46  rests on the lock rail  34 . The vertical gussets  68  on the tab feature  62  act to positively register the tab feature  62  against an outward edge  145  of the elongate slot  144  ( FIG. 14 ), thus preventing the flared end  66  of the tab feature  62  from becoming dislodged. The mounting fastener  56  is then assembled in the center pivot hole of the handle  52  and driven into the lock rail  34  to secure the lock assembly  32 . 
         [0041]    Functionally, the use of a single mounting fastener  56  speeds assembly while providing a secure method of mounting the lock assembly  32  to the lock rail  34 . The boss features  64  provide alignment of the lock assembly  32  on the inner sash  36 . The tab feature  62  can be formed to put a slight spring downward bias of the aft portion (i.e., the portion between the fastener  56  and the tab  62 ) of the lock assembly  32  against the mounting surface of the lock rail  34  to aid in securing the lock assembly  32  to the inner sash  36 . The downward spring bias can also mitigate the effects of gapping if the lock rail  34  profile thickness varies or there is warpage/bow present in the lock rail  34 . 
         [0042]    It is noted that the same aspects that facilitate the mounting of the lock assembly  32  can improve the performance of the locking system  30  under loading conditions. The tab feature  62  of the housing  46 , being located on the opposing side of the mounting fastener  56  from the engagement of the rotating cam  48  and keeper  38 , can operate to counter moments imparted to the lock assembly  32  under an axial load  150  ( FIG. 15 ). The greater distance between the tab feature  62  and the rotation axis  78 , the greater leverage for relieving the bending stress that is otherwise placed on the mounting fastener  56 . The width of the tab feature  62  can be maximized for better distribution and reduced stress under axial loads. Accordingly, the tab feature  62  provides additional strength that prevents the lock assembly  32  from being dislodged from the inner sash  36  due to axial loads between the cam  48  and the keeper  38 . 
         [0043]    Also, the boss features  64  are spaced forward of the rotating cam  48  center and laterally as far out as possible from the rotation axis  78  to provide rigidity and strength under torsion loads about the rotation axis  78 . The mounting fastener  56  acts as a strengthening member in the center pivot area as well as a means to help secure the lock assembly  32 . The mounting fastener  56  transfers the load into the lock rail  34  and helps prevent separation of the rotating cam  48  from the handle  52 . 
         [0044]    In certain embodiments, the lock assembly  32  can include either a detent feature molded in the housing  46  which interfaces with the rotating cam  48  or handle  52 , or have another separate component to create a detent feature. The detent feature acts to positively secure the rotating cam  48  in either the fully locked or the fully unlocked position, and can help prevent the cam from being jimmied to rotate out of the locked position. 
         [0045]    In another embodiment, a thrust washer (not depicted) can be utilized to help reduce axial play in the assembled components. Optionally, a thrust feature (not depicted) can molded in the one or more of the various components of the lock assembly  32  that interfaces with the housing  46 , rotating cam  48  or handle  52 , or another separate component to reduce axial play between the components. 
         [0046]    In the embodiments depicted herein, the non-limiting materials of construction for the lock assembly  32  include plastic for the housing  46  and handle  52  and metal for the rotating cam  48 , bushing  54  and mounting fastener  56 . Each of these components can be made of plastic, composite (e.g., fiberglass, plastic-impregnated wood), metal or other materials or combinations thereof known to the artisan. The locking system  30  can be used with vinyl plastic, aluminum, wood, composite or other window sash materials. 
         [0047]    References to relative terms such as upper and lower, front and back, left and right, or the like, are intended for convenience of description and are not contemplated to limit the invention, or its components, to any specific orientation. All dimensions depicted in the figures may vary with a potential design and the intended use of a specific embodiment of this invention without departing from the scope thereof. 
         [0048]    Each of the additional figures and methods disclosed herein may be used separately, or in conjunction with other features and methods, to provide improved devices, systems and methods for making and using the same. Therefore, combinations of features and methods disclosed herein may not be necessary to practice the invention in its broadest sense and are instead disclosed merely to particularly describe representative embodiments of the invention. 
         [0049]    For purposes of interpreting the claims for the present invention, it is expressly intended that the provisions of 35 U.S.C. §112(f) are not to be invoked unless the specific terms “means for” or “step for” are recited in the subject claim.