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TECHNICAL FIELD 
       [0001]    The application relates generally to casement windows and, more particularly, to a motorized window latching system. 
       BACKGROUND OF THE ART 
       [0002]    Casement windows are well known. Such windows typically have one or more window sash pivotable about a vertical axis between an open and a closed position. A latch bar is commonly employed to lock the window sash in its closed position in tight sealing engagement against the window frame. Such latch bars generally include a flat steel strip having various latch points therealong for engagement with corresponding keepers provided along an edge of the associated window sash. The latch bar is typically manually actuated by a pivotable lever or lock handle. 
         [0003]    Heretofore, the motorization of casement window latch mechanisms has been challenging. In most instances, access to the window latch bar is difficult and there is very little room to position the motorized operator. Also the motorized latch operator must not adversely affect the aesthetic of the window in order for the product to gain commercial acceptance. 
         [0004]    There is thus a need for a compact motorized latch operator that can be integrated into a casement window without adversely affecting the appearance thereof. 
       SUMMARY 
       [0005]    It is therefore an object to provide a compact motorized latch operator that can be integrated to a casement window. 
         [0006]    In one aspect, there is provided a motorized latch operator adapted to be retrofitted to a normally manually operated latching assembly of a casement window mounted in a building wall, the casement window having at least one window sash hingedly mounted in a casement for pivotal movement about a vertical axis between open and closed positions, keepers being provided along one side of the window sash for engagement with corresponding latches mounted on a vertical side frame member of the casement, the latches being operatively interconnected by a vertical latch bar mounted for longitudinal movement in a gap defined between the side frame member and a moulding member; the motorized operator comprising a reversible rotary motor mounted in one of an internal cavity of the casement and a cavity in the building wall next to the casement, a vertically supported lead screw drivingly connected to the reversible rotary motor, a slider threadably engaged on the lead screw and constrained to up and down linear movement in response to rotation of the lead screw by the reversible rotary motor, the slider being connectable to the lock bar to transmit the linear movement imparted to the slider by the lead screw to the lock bar in order to actuate the latches of the casement window. 
         [0007]    In a second aspect, there is provided a power-operated latch assembly for a casement window mounted in a building wall, the casement window having at least one window sash hingedly mounted in a window frame for pivotal movement about a vertical axis between open and closed positions; the power-operated latch assembly comprising at least two keepers mounted to the window sash for locking engagement with corresponding latches operated by a latch bar mounted for vertical movement along one vertical member of the window frame, a reversible operator mountable in one of a cavity defined in the building wall and an internal cavity defined in the window frame, a vertical push and pull rod disposed axially next to the latch bar, the push and pull rod being drivingly connected to the reversible operator, and a link between the push and pull rod and the latch bar, the link transferring the movement communicated to the push and pull rod to the latch bar. 
         [0008]    In a third aspect, there is provided a casement window comprising at least one window sash hingedly mounted in a window frame for pivotal movement about a vertical axis between open and closed positions, a power-operated latch mechanism for releasably locking the at least one window sash in the closed position, the power-operated latch mechanism comprising at least two keepers mounted to the window sash for locking engagement with corresponding latches operated by a latch bar mounted for vertical movement along one vertical member of the window frame, a reversible rotary motor mounted in one of a cavity defined in the building wall and an internal cavity defined in the window frame, a vertically supported lead screw drivingly connected to the reversible rotary motor, a vertically displaceable slider threadably engaged on the lead screw for linear movement therealong, and a link between the slider and the latch bar, the link transferring the movement communicated to the slider to the latch bar. 
         [0009]    Further details of these and other aspects of the present invention will be apparent from the detailed description and figures included below. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]    Reference is now made to the accompanying figures, in which: 
           [0011]      FIG. 1  is a perspective view of a double hung casement type window as seen from inside a room and having a motorized unlatching system mounted inside the central profiled post of the window casement, the front vertical moulding normally covering the central profiled post being omitted to reveal the normally hidden motorized unlatching system; 
           [0012]      FIG. 2  is a perspective view of the motorized unlatching system together with the window original latching hardware shown in isolation; 
           [0013]      FIG. 3  is a cross-sectional view taken along line  3 - 3  in  FIG. 1 ; 
           [0014]      FIG. 4  is a longitudinal cross-sectional view illustrating the motorized unlatching system in position in the central profiled post of the window casement; 
           [0015]      FIG. 5  is a perspective view of another model of double hung casement type window, the vertical moulding along one side of the central post of the window being broken away to show part of a motorized latching system; 
           [0016]      FIG. 6  is a vertical cross-sectional view illustrating the details of the motorized latching system of  FIG. 5 ; 
           [0017]      FIG. 7  is a perspective view of a single hung casement window, the vertical moulding along one side of the window frame being omitted to reveal details of a motorized latching system connected to the original manual latching system of the window; and 
           [0018]      FIG. 8  is vertical cross-sectional view illustrating the details of the motorized latching system shown in  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]      FIG. 1  illustrates a first example of a conventional casement window  10  to which a motorized latching system or operator  12  can be integrated or retrofitted to provide for motorized latching and unlatching of the window. The illustrated exemplary casement window  10  is of conventional double hung casement type comprising a pair of window sashes  14  hingedly mounted in a casement  16  for pivotal movement between open and closed positions about mobile vertical axes at opposite sides of the casement  16 . 
         [0020]    The casement window  10  is provided with latching hardware to releasably secure the window sashes  14  in their closed position. The latching hardware can comprise a plurality of keepers  18  (two in the illustrated example) on each window sash  14  for engagement with corresponding attachment points or latches  20  mounted on opposed longitudinal exterior sides of the central profiled post  22  of the casement  16 . The latches  20  capture the keepers  18  and operation of the latches  20  draw the corresponding window sash  14  into its closed position where it is locked. In the closed position, the window sash  14  is seated in the frame and compresses weather stripping (not shown) to seal the window assembly. In the illustrated example, the latches of each set of latches  20  are interconnected by a latch bar  24  adapted to transmit the movement from one latch to another, thereby allowing for joint operation of the latches  20  of a same set. The latch bars  24  are typically made from flat steel strips mounted for linear sliding movement against the exterior longitudinal sides of the central profiled post  22  of the casement  16 . 
         [0021]    Instead of manually actuating the interconnected latches  20  via a conventional lever or handle provided at one of the latching points on each side of the central profiled post  22 , it is herein proposed to nest a power-operated or motorized latch actuator system  12  in an existing frontal opening defined in the central profiled post  22  and to connect the system  12  directly to the existing latch bars  24  on each side of the central profiled post  22 . Once installed, the motorized system  12  is hidden behind the front moulding (not shown) normally covering the post  22  when viewed from inside the room in which the window is mounted. By taking advantage of the existing free internal space offered by the central profiled post  22 , it is possible to completely conceal the system  12  within the window casement  16 , thereby preserving the overall appearance of the window. 
         [0022]    As best shown in  FIG. 2 , the system  12  generally comprises at least one reversible actuator, such as electrical reversible rotary motor  26 , a push and pull rod which can take the form of a lead screw  28  drivingly connected to the motor  26 , a slider  30  threadably engaged on the lead screw  28  for linear movement within the profiled post  22  ( FIG. 1 ) in the upward and the downward directions, and a pair of link plates  32  mounted to opposed sides of the slider  30  in order to rigidly connect the slider  30  to the lock bars  24  of the window  10 . An example of a suitable actuator is the 12 DVC E Type Inline DC Gearmotor Model No. 8501 manufactured by Merkle-Korff Industries. The dimensions of the selected actuator must allow the same to be fully contained within the central profiled post  22 . The motor  26  is connected to a source of power (not shown), such as a battery. The lead screw  28  can consist of a stainless steel screw with ACME threads. The slider  30  can be manufactured in a block of polytetrafluoroethylene or from another solid block of low friction material in order to minimize the friction between the lead screw  28  and the slider  30 . 
         [0023]    The system  12  further comprises a support  36  for supporting the motor  26  and the lead screw  28  and facilitating mounting of the system  12  within the central profiled post  22  of the casement window. The support  36  comprises an elongated back  38  and top and bottom L-shaped plates  40  and  42  mounted at opposed ends of the elongated back  38 . The elongated back  38  provides a mounting surface for fixedly mounting the system  12  into central profiled post  22  of the casement  16 . Holes can be defined through the back of the support  36  for receiving mounting screws or the like. The motor  26  is mounted to the undersurface of the bottom L-shaped plate  42 . A support block  44  having a screw receiving hole depends from the top L-shaped plate  40  for receiving a tip end portion of the lead screw  28 . Limit switches  46   a,    46   b  and  46   c  are mounted to the front face of the support back  38  above and below the slider  30 . Projections  48   a,    48   b,    48   c,  such as screws, are provided on the top and bottom surfaces of the slider  30  to trigger the limit switches  46   a,    46   b  and  46   c  when the slider  30  reaches its top and bottom travel limits. The limit switches  46   a,    46   c  are operatively connected to the motor  26  to shut down the same and reverse the direction of movement once triggered by a corresponding one of the triggering projections  48   a,    48   c,  thereby defining the range of motion or stroke of the slider  30  on the lead screw  28 . The third limit switch  46   b  is used as an interlock. The limit switch  46   b  is provided to prevent the motor (not shown) used to displace the window sashes  14  between their open and closed positions from being operated when the latches  20  are engaged with the keepers  18 . It is provided to “sense” the lock state of the window sashes. It can also be used to prevent the motor  26  of the power operated latching system from being operated when the window sashes are opened. 
         [0024]    The motor  26 , the lead screw  28 , the slider  30 , the support block  44  and the limit switches  46   a,    46   b,    46   c  are pre-assembled on the support  36  and this sub-assembly is mounted within the central profiled post  22 , such as by screwing the support back  38  to a corresponding back surface of the casement window central profiled post  22 . As shown in  FIG. 4 , the central post  22  is provided in the form of an extrusion having a generally C-shaped profile with a front open face. The central post  22  has a frontal recess defined by sidewall surfaces  50  and inwardly projecting frontal wall surfaces  52 . The slider  30  has a generally T-shaped body including a rearwardly projecting shank portion  54  and lateral shoulders  56 . The shank portion  54  is received between the frontal wall surfaces  52  of the profiled post  22  with the lateral shoulders  56  resting against a front side of the frontal wall surfaces  52  between said sidewall surfaces  50 . This arrangement prevents the slider  30  from rotating together with the lead screw  28 . The slider  30  is thus constrained to move linearly in the upward or the downward direction depending whether the motor  26  is rotatably driving the lead screw  28  in the clockwise or the counter-clockwise direction. 
         [0025]    Still referring to  FIG. 4 , it can be appreciated that the lock bars  24  interconnecting the latches  20  ( FIG. 1 ) are guided in vertical tracks defined at the outer sides of the central profiled post  22 . The link plates  32  are positioned laterally outwardly from the sidewall surfaces  50  of the post  22  and are fixedly attached to the lock bars  24  by fasteners such as screws or the like. Vertically elongated slots  58  had to be machined (also see  FIG. 3 ) in the post sidewall surfaces  50  for allowing the link plates  32  to be rigidly connected to the slider  30  by means of shoulder screws  57 . In this way, the linear movement of the slider  30  inside the post  22  can be simultaneously transmitted to both latch bars  24  on the opposed sides of the central profiled post  22 . The length of the elongated slots  58  is selected to accept the full stroke of the slider  30  as set by the position of the limit switches  46 . 
         [0026]    In use, a remote control can be used to operate the system  12 . A wireless control receiver (not shown) can be mounted in the building wall underneath the window frame for receiving control commands and transmitting same to the electric motor  26 . The rotational movement of the lead screw  28  causes the linear displacement of the slider  30  which in turn push or pull on the lock bars  24  (depending in which direction the screw is rotated) to actuate the latches  20  in order to lock or unlock the window. 
         [0027]    If more torque is required to operate the latches, a second motor and a second lead screw could be added to the above described latch operator assembly. The second motor could be mounted to the top L-shaped plate  40  of the support with the second lead screw laterally offset with respect to the first lead screw  28 . The motors would be synchronized but operated to drive the first and second lead screws in opposed directions. 
         [0028]      FIGS. 5 and 6  illustrate another example of the integration of a motorized latch actuation system  12 ′ to a double hung type casement window  10 ′ but this time for a model of window having a solid central post  22 ′ having no internal cavity in which the above described components of the motorized latching system could potentially be mounted. The only space available to access the lock bars  24 ′ is the ¾ inch to 1 inch gap existing between the central post  22 ′ and the vertical moulding  23  on each side of the post  22 ′. This does not leave enough room to accommodate the motor. 
         [0029]    The motor  26 ′ had thus to be disposed in a rectangular wooden box or casing  27  mounted to the casement  16 ′ underneath sill  29 . The casing  27  forms a hollow window frame extension for receiving window operator equipment and the like. The motor  26 ′ is thus concealed in the building wall below the original window frame. The dimensions of the casing  27 , notably the height thereof, are greatly limited by the presence of the structural or skeleton members of the building wall in which the window is mounted. In view of the small space available underneath the casement window  10 ′, the motor  26 ′ is horizontally disposed in the casing  27  and a universal joint  31  is used to connect the motor  26 ′ to the lead screw  28 ′ extending vertically along the side of the central post  22 ′ in the gap defined between the side moulding  23  and the central window post  22 ′. 
         [0030]    The lead screw  28 ′ extends through a hole  33  defined in the window sill  29  and is vertically supported by a bottom support block  37  mounted to the central post  22 ′ underneath the sill of the window  10 ′. As shown in  FIG. 6 , the lead screw  28 ′ has a shoulder resting on top of the bottom block  37  to prevent the screw  28 ′ from sliding downwardly under gravity into the lead screw passage defined in the bottom block  37 . The upper end or tip of the lead screw  28 ′ is received in a hole defined in a top support  44 ′ screwed or otherwise secured to the side of the central post  22 ′. The top support  44 ′ is also contained in the gap between the post  22 ′ and the moulding  23 . 
         [0031]    The limit switches  46   a ′,  46   b ′ and  46   c ′ are also directly mounted to the side of the post  22 ′ below the internally threaded slider  30 ′ mounted on the lead screw  28 ′ in the gap between the post  22 ′ and the moulding  23 . A L-shaped triggering finger  39  extends downwardly from the slider  30 ′ for triggering the limit switches  46   a ′,  46   b ′ and  46   c ′ when the slider  30 ′ reaches the end of its stroke. 
         [0032]    The mounting of the slider  30 ′ against the side wall of the central post  22 ′ locks the slider  30 ′ against rotation and constrains the slider  30 ′ to move linearly along the side wall of the post  22 ′ in response to the rotation of the lead screw  28 ′. An elongated strip or rod  41  extends upwardly from a post facing side of the slider  30 ′ in order to rigidly connect the same to the existing lock bar  24 ′ interconnecting the latches  20 ′ of the window  10 ′. The linear movement of the slider  30 ′ on the lead screw  28 ′ can thus be transferred to the existing lock bar  24 ′ in order to latch and unlatch the window. 
         [0033]    It is understood that a similar motorized latch operator is provided on the other side of the central post to operate the lock bar interconnecting the latches associated to the second window sash (not shown). 
         [0034]      FIGS. 7 and 8  illustrate another example of the integration of a motorized latch actuation system  12 ″ to an originally manually actuated latching system of a single hung type casement window  10 ″. In this example, the window lock bar  24 ″ interconnecting the latches  20 ″ on one side of the window frame is disposed further towards the outside of the room in which the window is mounted. The casing  27 ″ secured underneath the window frame in the building wall and holding the motor  26 ′ is not aligned with the lock bar  24 ″. The casing  27 ″ is located further towards the inside of the room relative to the lock bar  24 ″. As will be seen herein after, this misalignment problem is overcome by connecting the motorized system  12 ″ to an existing link  70  originally joined to the lever/handle (not shown) of the lower manual latch  20 ″. 
         [0035]    As shown in  FIG. 8 , the motor  26 ′ is horizontally mounted in casing  27 ″ which is disposed in the building wall underneath the window frame. The motor  26 ″ is drivingly connected to a vertically disposed lead screw  28 ″ via universal joint  31 ″. The lead screw  28 ″ extends through a hole defined in the window sill and has a top head  71  retained captive between a base  72  and a cover  74 . The base  72  and the cover  74  are made of a low friction material and are used to support the lead screw  28 ″ in position. The base  72  is mounted on a top surface of the window sill and has a through bore defined therein for allowing the lead screw  28 ″ to pass therethrough. A recess is defined in a top surface of the base  72  for receiving a split washer  76 . The washer  76  is mounted about the lead screw  28 ″ underneath head  71 . The cover  74  has a recess defined in an undersurface thereof for accommodating the screw head  71  and is screwed or otherwise suitably secured to the base  72 . A horizontal moulding (not shown) covers the sill of the window to conceal the base  72  and the cover  74 . 
         [0036]    A low frictional material rectangular sleeve  78  is installed in the hole defined in the window sill to provide for smoothly guided movement of slider  30 ″ on the lead screw  28 ″. The sleeve  78  is configured to lock the slider  30 ″ against rotation while providing for smooth linear gliding movement therein. An elongated flattened rod or strip  80  is attached to the slider  30 ″ and extends vertically upwardly through aligned slotted holes defined in the base  72  and cover  74 . The upper end of the strip  80  is pivotally connected to existing link  70  which is, in turn, connected to the lock bar  24 ″ joining all the latches  20 ″ of the window. The pull and push strip  80  can be guided at the upper end thereof by a guide  82  mounted to the side member of the window frame on which the latches  20 ″ are mounted. The vertical moulding (not shown) of the side member of the window frame conceal all the mechanism disposed therealong. 
         [0037]    As shown in  FIG. 7 , the limit switches  46   a ″,  46   b ″,  46   c ″ are mounted on the side of the frame next to the upper latch  20 ″ so as to be triggered by the components thereof. 
         [0038]    The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.

Summary:
A power-operated latch is integrated to a casement window for selectively locking and unlocking a vertically hinged window sash. The power-operated latch is adapted to be concealed in the window frame and is directly connectable to the existing window latch hardware. A reversible rotary motor drives a vertically supported lead screw on which a slider is threadably engaged for selectively raising and lowering a longitudinally movable latch bar.