Abstract:
A casement assembly comprising a casement frame defining a passageway in which is moveably mounted a closure element that can be moved to open and close the passageway relative to the casement frame. A latch is provided on the closure element for locking the closure element relative to casement frame. The latch includes a rotating cam having an eccentric surface that abuts an inner end of a laterally sliding rod whose outer end is brought into and out of interference with the casement frame to lock the moveable element with respect to the casement frame.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention generally relates to a casement defining an opening in a structure, such as a wall, in combination with a closure element that is movable with respect to the casement for opening or closing at least a portion of the casement opening; and, more particularly, to a latch mechanism for fixing the relative position of the closure element with respect to the casement, preferably in the closed position. 
     2. Related Art 
     A casement assembly comprising a combination of a casement frame and a closure element is well known and finds common examples in security screens, sliding glass doors, or double hung windows, to name a few examples. Generally, the casement frame is positioned within a wall or similar structural element to define a passage therethrough. The closure element (generally a window, screen or door) is movable (generally slidable or pivotal) with respect to the casement frame for alternatively opening or closing the passageway. 
     For safety, it is common to provide a latch mechanism for locking the closure element in a fixed position relative to the casement frame, preferably in the closed position. Previous latch mechanisms typically include one or more locking rods mounted to the closure element and laterally movable between a retracted and extended position for inserting and removing an outer end of the bar into and out of engagement with the casement frame to prevent the movement of the closure element with respect to the casement frame. A laterally movable or rotatable handle or knob was directly mechanically coupled to the inner end of the rod for moving the rod between the extended and retracted positions as the handle is slid or rotated. The direct mechanical coupling between the rod inner end and the knob or handle typically included rotatably pinning the end of the rod to the handle or providing an intermediate link having one end pinned to the rod and the other end pinned to the handle or knob. Examples of such latch mechanisms with direct mechanical links are illustrated in U.S. Pat. No. 2,708,478, filed May 17, 1955, U.S. Pat. No. 2,883,225, filed Oct. 16, 1953, U.S. Pat. No. 4,362,328, issued Dec. 7, 1982, U.S. Pat. No. 4,803,808, issued Feb. 14, 1989, U.S. Pat. No. 5,090,750, issued Feb. 25, 1992, U.S. Pat. No. 5,595,408, issued Jan. 21, 1997, and U.S. Pat. No. 5,806,353, issued Sep. 15, 1998 to name a few. 
     A disadvantage of the prior art latches lies in the direct mechanical linkage, which can often be difficult to extend and retract because of the inherent friction or resistance in the mechanical linkages. Many of the mechanical linkages change angular orientation with respect to the handle or knob as it is rotated, resulting in quickly varying relatively small lever arms that require applying relatively large and varying rotational forces to the handle or knob to effect the extension or retraction. The magnitude and varying nature of the operational force results in jerky operation and sometimes a very high initial force. The combination of these effects can often lead to the user having to apply a relatively very large initial force until the inherent friction or resistance is overcome, resulting in the user feeling as if the latch mechanism has broken away. An additional problem lies in that the various components are typically metal and the linkages can rust, increasing the force necessary to overcome the additional resistance and exacerbating the initial force problem. 
     SUMMARY OF THE INVENTION 
     There is a desire to have a casement enclosure assembly with a latch that addresses the disadvantages of the prior art and permits the easy and repeatable locking/unlocking of the closure with respect to the casement. The invention addresses this desire by ameliorating the prior art disadvantage by providing a latch mechanism that requires a relatively low initial force alone or in combination with a casement assembly. The casement assembly comprises a casement frame that defines a passageway and a closure element that is moveably mounted to the casement frame and closes at least a portion of the passageway. The latch mechanism comprises a rod and a cam for operably moving the rod. The rod has inner and outer ends and is slidably mounted to the closure element for lateral movement between an extended position, preventing the movement of the closure element relative to the casement frame, and a retracted position, permitting the sliding movement of the closure element relative to the casement frame. The cam has at least one eccentric surface that is in substantially constant abutting relationship with the rod inner end and is rotatably mounted to the closure element for rotation between a first position and a second position for moving the rod between the retracted and extended positions. 
     The latch can further comprise a biasing device that biases the rod inner end against the eccentric surface. The biasing device is operably coupled between the rod and one of the closure element and the casement frame. Preferably, the biasing device comprises a mounting bracket having an eyelet that slidably receives the rod and a coil spring that is concentrically positioned relative to the rod and having one end connected to the bracket and another end connected to the rod whereby when the rod is in the extended position, the spring is compressed and applies a biasing force to the rod to urge the rod toward the retracted position. 
     The latch can further comprise a handle mounted to the cam for rotating the cam between the first and second positions. The handle is preferably mounted to the cam at a location is spaced from the cams rotational axis. 
     The cam can also comprise a stop that abuts the rod when the cam is in the second position to prevent the continued rotation of the cam beyond the second position. Preferably, the stop is a projection that extends away from the eccentric surface. 
     The casement assembly can include a catch that couples with the rod outer end when the rod is in the extended position to form the interference relationship. The catch can be a portion of the casement that the rod outer end overlies or an opening formed in the casement frame and sized to receive the outer end of the rod. There can also be multiple openings provided along the casement frame to permit the fixation of the closure element at discreet locations along the casement frame. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a front view of a safety screen assembly comprising a casement frame and closure element that is locked to the casement frame by a latch according to the invention; 
     FIG. 2 is an enlarged view of the latch of FIG. 1 with the latch shown in the locked position; 
     FIG. 3 is similar to FIG. 2 except that the latch is shown in the unlocked position; 
     FIG. 4 is a top view of the latch in FIG. 2; 
     FIG. 5 illustrates the latch of FIG. 1 in the context of a double hung window; and 
     FIG. 6 illustrates the latch of FIG. 1 in the context of a sliding glass door. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a casement assembly  10  in the context of a security screen having a casement frame  12  whose interior defines a passage  14  in which is moveably mounted a closure element  16  in the form of a screen. The screen comprises a frame  18  whose upper edge is pivotally mounted to the casement frame  12  by a hinge (not shown) for pivotal movement rearwardly as viewed in FIG.  1 . 
     The casement assembly  10  further includes a latch  20  fixably mounted to the closure element  16 . The latch  20  comprises a pair of opposing rods  22  that are slidably mounted with respect to the closure element by corresponding brackets  24 . Each rod has an inner and outer end  26 ,  28 , respectively. Each of the brackets  26  has a pair of eyelets  30  that slidably receive the rod  22  to constrain the rod  22  for lateral movement with respect to the closure element  18 . A coil spring  32  is concentrically mounted over each rod  22 . One end of the spring  32  abuts one of the eyelets  30  and the other end of the spring  32  is fixed to the rod  22 , preferably by abutting a clip  34  mounted to the rod. 
     The latch  20  further comprises a cam assembly  42  comprising a cam body  44  having opposing eccentric surfaces  46 ,  48 , which terminate in projections or stop flanges  50 ,  52 . A handle  54  extends from the cam body  44  and is connected to the cam body at a location spaced from the rotational axis  55  of the cam body. 
     The cam assembly  42  further comprises a mounting bracket  56  for mounting the cam body  44  to the window  18 . The cam bracket  56  has opposing eyelets  58  that slidably receive the inner ends  26 ,  28  of the rods  22 ,  24 . Preferably, the cam body  44  is rotatably pinned to the cam bracket  56  by a rivet  62 , which defines the rotational axis  55 . 
     Optionally, a latch shield  64  can be disposed between the cam bracket  56  and the window  18  to deter access to the handle  54  and cam body  44  through the screen. The shield and brackets are secured to the frame by suitable mechanical fasteners. A locking tab  66  can be provided for additional locking and overlies the frame when the cam is in the closed position. 
     The operation of the latch mechanism will be described with reference to FIGS.  2 - 4  and assuming the latch mechanism begins in the unlocked position as illustrated in FIG.  3 . In the unlocked position, the eccentric surfaces are oriented so that the short width side of the eccentric surface is presented to the inner ends  26  of the rods  22  and the springs bias the inner ends  26  into abutting relationship with the eccentric surfaces  46 ,  48 , respectively. In the unlocked position, the rod outer ends  28  are in the retracted position and lie within the passageway  14  and do not overlie the casement frame  12 . Thus, the screen closure element  14  is free to pivot relative to the casement frame  12 . 
     As the handle is rotated clockwise as viewed in FIGS. 2 and 4, the portion of the eccentric surfaces  46 ,  48  that are spaced farthest from the pivot axis  55  are presented to the inner ends  26 ,  28 , which are held in constant abutment with the eccentric surfaces  46 ,  48  by the springs. Upon the rotation of the handle, the inner ends  46 ,  48  follow the eccentric surfaces  46 ,  48  until the stop flanges  50 ,  52  are brought into contact with the rods  22 ,  24 , which limit further rotation of the cam body  44 . The rotation of the cam body  44  results in the lateral movement or extension of the rods  22 ,  24  from the retracted position to the extended position where they overlie a portion of the casement frame  12  to prevent the outward pivoting of the closure element  18 . 
     FIG. 5 illustrates the latch  20  in the context of a double hung window assembly  60 . The double hung window assembly  60  comprises a casement frame  62  defining a passageway  64  in which are positioned closure elements  66  in the form of windows. Each of the windows comprises a window frame  70 , which mounts a pane of glass  72 . The windows  66  are slidably mounted with respect to the casement frame  62 . 
     The latch  20  is mounted to one of the frames  70  of the window  66  and operates identically as previously described except that the outer ends  28  of the rods do not overlie the casement frame  62  in the extended position, but instead are received within openings  72  on the casement frame. There can be multiple openings  72  spaced vertically along the casement frame  62  to permit the locking of the window  66  at various vertical positions relative to the casement frame  62 . 
     FIG. 6 illustrates the latch  20  in the context of a sliding glass door assembly  80 , which comprises a casement frame  82  defining a passageway  84 . A pair of sliding glass doors  86  are slidably mounted within the casement frame  82  to permit the opening and closing of the passageway  84 . Each of the sliding glass doors  86  comprises a frame  88  that is slidably mounted to the casement frame and which mounts a glass or screen element  90 . 
     The latch  20  is mounted to one of the sliding glass doors  86  in a manner similar to that of the double hung window of FIG. 5 except that the latch is vertically oriented instead of horizontally oriented. The casement frame  82  also includes openings  92  that receive the ends  28  of the rods when they are in the extended position in the same manner as described for the double hung windows. As with the double hung window of FIG. 5, the openings  92  can be spaced along the casement frame  82  so that the sliding door  86  can be latched in any one of a variety of horizontal positions. 
     The latch, according to the invention, can be used in a variety of contexts such as doors, windows, and cabinets. Door examples include patio doors, carport doors, firewall doors, overhead doors, sliding glass doors, screen doors, and safety screen doors. Window examples include single hung windows, double hung windows, triple hung windows, tilt windows, slider windows, casement windows, and swivel windows. Cabinet examples include flammable liquid storage cabinets, file cabinets, industrial cabinets and desk cabinets. The latch overcomes the disadvantages of prior art latches by maintaining a constant abutting relationship between the eccentric surface on the cam and the inner end of the rod wherein the eccentric surface extends and retracts the rods without changing the angular orientation of the rods to thereby eliminate the need for the prior art mechanical linkages between the rods and the handle. 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.