Window lock
BACKGROUND OF THE INVENTION 
     This invention pertains to window locks and, more particularly, to a check rail lock having a pair of locking members that can move to each side of the vertical muntin of an adjacent double hung window sash to engage catch means mounted in the center of the window sash. The window lock incorporates novel structural elements for performing the window locking functions. 
     Many different types of check rail locks for double hung windows are known in the art. It is common procedure to install the check rail locks on residential double hung windows without mutins in the center of the horizontal check rail for esthetic reasons. On windows with a center vertical muntin or grill, it usually is impractical to position the check rail lock in the center of the horizontal check rail as the space usually accommodated by the check rail lock keeper or catch means is replaced by the vertical muntin. As a result, most known check rail locks are of a construction that must be offset from the center of the horizontal check rail in order to align with a lock keeper or catch means which is mounted at a position laterally displaced from the vertical muntin. 
     SUMMARY 
     A primary advantage of the invention disclosed herein is in the construction of a check rail lock for use with double hung window sash having a vertical muntin wherein the check rail lock may be mounted in the center of the horizontal check rail. 
     A feature of the invention is to provide a window lock wherein the parts of the window lock in moving to a final locked position cause a locking member to move outwardly to engage catch means carried by the upper window sash and then to have simultaneous upward and inward movement to align and seal double hung window sash tightly against the top and bottom of the window frame and draw the adjacent check rails of the window sash tightly together. 
     Still another feature is to provide a check rail lock having a casing mounting movable parts including a manually operable operating unit having a pair of operating members movable between locked and unlocked position, a locking unit having a pair of locking members movable between advanced and retracted positions and, in the advanced position, bringing a pair of locking notches into engagement with spaced-apart sections of a catch means positionable to either side of a window sash vertical muntin, and pin and slot means interconnecting the casing, the operating unit, and the locking unit whereby movement of the operating unit toward locked position causes advance of the locking unit to the advanced position to bring the locking notches into relation with the catch means and further movement of the operating unit causes simultaneous lifting and retracting of the locking unit for tight sealing of the check rail members of adjacent sash to each other and of the sash to the window frame with the forces being applied centrally because of the central mounting of the window lock relative to the window sash. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a plan view of the window lock shown in locked position in association with parts of a double hung window with parts of the window shown in section and parts of the window lock broken away; 
     FIG. 2 is a vertical section, taken generally along the line 2--2 in FIG. 1; 
     FIG. 3 is a vertical section, taken generally along the line 3--3 in FIG. 1 and with the window lock in unlocked position; 
     FIG. 4 is a view, similar to FIG. 3, showing the window lock in intermediate position and with a locking member fully advanced; 
     FIG. 5 is a view, similar to FIG. 3, showing the window lock in locked position; and 
     FIG. 6 is a vertical section, taken generally along the line 6--6 in FIG. 1, with the window lock in locked position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The window lock disclosed herein is a check rail window lock intended primarily for use with double hung windows having adjacent upper and lower window sash as shown in the drawings. The window lock is also usable with other types of windows, such as horizontal windows having horizontal sliding panels. 
     The window lock has a casing, indicated generally at 10, mountable on a rail member of one window sash and housing the movable elements of the lock and a catch means, or keeper, indicated generally at 15, mountable on a rail member of the other window sash. 
     The catch means 15 is in the form of a sheet metal stamping with parts formed at right angles to have a planar base 16 which may be positioned upon the top surface of the lower check rail 17 of an upper sash of a double hung window and be fastened thereto by attachment members 18. The planar base 16 has a length to extend to either side of a vertical muntin 20 of the upper window sash and is recessed as shown in FIG. 1 at 21 to permit mounting of the catch means 15 centrally of the lower check rail 17 by spanning of the vertical muntin 20. An integral, vertically-extending planar section 25 of the catch means is positioned adjacent the meeting line of the check rails of the window sash and has two vertically-extending, generally rectangular slots 30 and 31 which terminate short of the upper edge of the planar section 25 to provide means for engagement by locking notches of locking members to be described. 
     The casing 10 forms an enclosure and guide structure for movable parts of the window lock, with the casing having a top wall 40 and a pair of side walls 41 and 42 depending therefrom. A pair of outwardly-turned flanges 43 and 44 associated one with each side wall receive attachment members 45 for mounting the casing to the upper check rail 50 of the lower window sash. 
     The depending side wall 41 has a pair of inwardly-turned guide tabs 51 and 52 lying in the same plane as the outwardly-turned flange 43 and the depending side wall 42 has a pair of inwardly-turned guide flanges 53 and 54 which lie in the same plane as the outwardly-turned flange 44. 
     The casing 10 has a depending rear wall 60 which terminates short of the plane of the guide tabs 51-54 and which also has its ends spaced from the depending side walls 41 and 42 to provide for movement and guiding of parts of an operating unit between the ends of the depending rear wall 60 and the inner surface of the depending side walls 41 and 42. 
     The operating unit is preferably formed as a sheet metal stamping having two spaced-apart vertical sides 70 and 71 extending upwardly from a planar connecting section 72 which has an upwardly-turned planar rear panel 73 which coacts with the rear wall 60 of the casing to limit the movement of the operating unit to a locked position, as shown in FIG. 6. The planar sides 70 and 71 of the operating unit each form an operating member and pass between the ends of the depending rear wall 60 and lie adjacent the inner faces of the casing side walls 41 and 42. Angularly-extending tabs 75 and 76 at the rear of the operating members 70 and 71, respectively, provide a means for manual engagement to operate the lock and optionally provide an attaching means for a trim cover, if desired. The operating members 70 and 71 each have a downwardlyand forwardly curved slot 77 and 78, respectively, which form part of pin and slot means for causing operation of the lock structure. In the movements of the lock components, the operating unit is guided within the casing by having lower surface of the planar connecting section 72 movable on the guide tabs 51-54 and having the upper surfaces of the operating members 70 and 71 engage against the under surface of the casing top wall 40. 
     A locking unit preferably in the form of a sheet metal stamping has a pair of spaced-apart vertical sides 80 and 81 each forming a locking member and extending upwardly from a connecting planar section 82 which extends to the rear of an inclined rear edge 83 of the locking members. Each of the locking members 80 and 81 is of a height less than the vertical interior dimension of the casing 10 with a downwardly-inclined upper edge to permit a pivoting movement between a lower position, shown in FIGS. 3 and 4, and a final locking position, shown in FIG. 6. Each locking member has a shaped forward end to provide a pair of locking notches 83 and 84, respectively, to interfit with the rectangular slots 30 and 31 in the catch means to lock the window elements together. Additionally, each of the locking members 80 and 81 have an opening 86 and 87, respectively, extending therethrough and of a size to receive a guide pin 90 in the form of a generally round member and secured in position by enlarged heads 91 and 92 positioned externally of the casing 10. 
     The depending side walls 41 and 42 of the casing each have a slot therein with a horizontally-extending section 95 and 96 and an upwardly and rearwardly angled connecting section 97 and 98, respectively. The guide pin 90 extends through the slots in the casing side walls and also extends through the downwardly and forwardly curved slots 77 and 78 of the operating members of the operating unit. These connections along with extension of the guide pin through the openings 86 and 87 define pin and slot means for the window lock operation. The guide pin 90 associates the operating unit and the locking unit integrally with the casing 10 and provides a cam bearing member to actuate the locking unit in response to movement of the operating unit. 
     The window lock is shown in unlocked position in FIG. 3 with adjacent check rails 17 and 50 in general alignment. The operating unit is moved from the unlocked position, as shown in FIG. 3, toward the right by pressing on the operating tabs 75 and 76 which causes the guide pin 90 to move to the right and be retained at the lower end of the curved slots 77 and 78 because the guide pin is travelling in the horizontal sections 95 and 96 of the slots in the casing side walls. This advancing movement also simultaneously advances the locking unit because of the guide pin 90 extending through the openings 86 and 87 of the locking members. This initial stage of movement ends with the parts positioned as shown in FIG. 4 wherein the locking notches 83 and 84 have passed through the catch means slots 30 and 31 and have passed to both sides of the vertical muntin 20 of the upper window sash. Further advancing movement of the operating unit to the position shown in FIG. 5 causes the guide pin 90 to move upwardly relative to the curved slots 77 and 78 of the operating unit and, at the same time, to move rearwardly. This action results because the guide pin 90 must follow the upwardly and rearwardly angled sections 97 and 98 of the casing slots. This causes an upward pivoting and retracting movement of the locking members 80 and 81 to the position shown in FIGS. 5 and 6 to raise the upper sash and lower the lower sash to seat the sash tightly against the top and bottom of the window frame and the catch means 15 has been drawn toward the casing 10 to draw the check rails 17 and 50 tightly together. This pivoting action is facilitated by having the rear edge of the connecting planar section 82 of the locking unit underlying the depending rear wall 60 of the casing, as shown in FIGS. 4 and 6. The advance of the operating unit to the locked position is physically limited by the upwardly-turned planar rear panel 73 of the operating unit abutting against the depending rear wall 60 of the casing. Any force exerted on a window sash in a direction to unlock the window is ineffective to release the window lock. 
     Unlocking of the window lock is effected by movement of the operating unit toward the left, as viewed in FIGS. 5 and 6, and with the movement of the parts being the reverse of that described in the locking action, to have the parts returned to the unlocked condition, shown in FIG. 3.