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CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is a divisional of U.S. patent application Ser. No. 11/081,328, filed on Mar. 15, 2005, by the present applicant. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to curtain wall systems and, more particularly, to a connection between curtain wall panels to structural members of the curtain wall. 
     BACKGROUND ART 
     Curtain walls are widely used as exterior sheathing of buildings, especially of the commercial or institutional type. Curtain walls typically consist of glass panels defining a major portion of the exterior surface of the building, with structural members separating the glass panels. A type of curtain wall is known as VEC facade, or structural glazing, and is characterized by the absence of exposed fastener devices between adjacent glass panels, from an outer point of view. In VEC facades, a transparent/translucent panel is glued (or secured) to a sash off site to form a glazing panel, which sash will cooperate with the structural members when the glazing panel is connected to the framing. 
     One of the major costs associated with curtain walls is the manpower required at installation. More specifically, once the structural members (e.g., mullions and transoms) have been secured to the building framing, a substantial amount of work is required to secure the glazing panels between the structural members. The glazing panels must be precisely positioned between the structural members, and supported in position while fasteners are implanted about the periphery of a sash of the glazing panel. 
     In the case of VEC facades, space is limited between adjacent glass panels for esthetic considerations, thereby rendering the implanting of fasteners more difficult. The spacing between adjacent panels in VEC facades is such as to allow workers to implant the fasteners to secure the glass panels to the vertical members. 
     The amount of work and time required to install curtain walls is substantial, and is associated with other problems pertaining to the logistics of construction sites. For instance, the amount of time required is often in the order of several days, thereby potentially exposing the construction sites to problematic weather conditions, such as rain and wind. This may cause delays in scheduling on the construction site. Moreover, the amount of time required delays the occupancy of the building. 
     U.S. Pat. No. 5,263,292 (hereinafter “patent &#39;292”), issued to Holland et al. on Nov. 23, 1993, describes a building panel system in which anchor sockets are secured to the building framing. The anchor sockets are shaped so as to receive in snap-fit engagement legs of connectors secured to the glass panels. A pressure gasket is then forced into the interstitial space between the legs of adjacent panels, so as to prevent the escape of the legs from their engagement with the anchor sockets. 
     The building panel system of patent &#39;292 describes a simplified installation of the glass panel to the structural members in that the glass panels are snap-fitted to the structural members without additional fasteners. However, the legs are subjected to plastic deformation when the glass panels are connected to the structural members. This requires a nonnegligible amount of force to secure the glass panels to the structural members. Also, the integrity of the connection between the glass panels and the structural members is dependent on these legs that undergo plastic deformation, whereby safety devices such as the pressure gasket are required. Finally, the configuration of the anchoring means is such that a glass panel must be destroyed to be removed from the structural members. It is occasionally required to remove glass panels, for instance when moving large furniture. In such cases, removing a glass panel becomes a costly solution. 
     SUMMARY OF INVENTION 
     Therefore, it is a feature of the present invention to provide a novel curtain wall system. 
     It is a further feature of the present invention to provide a curtain wall system in which connection devices automatically lock the glazing panel to a frame of structural members upon positioning the glazing panel within the frame of structural members. 
     It is a still further feature of the present invention to provide a novel method for installing a glazing panel to a frame of structural members in a curtain wall system. 
     It is a still further feature of the present invention to provide a method for installing a glazing panel to a frame of structural members in a curtain wall system in which the glazing panel is automatically locked to a frame of structural members upon positioning the glazing panel within the frame of structural members. 
     Therefore, in accordance with the present invention, there is provided a connector device for a curtain wall system of the type having structural members secured to the building framing to define frames to support glazing panels, the glazing panels each having a sash by which the glazing panels are secured to the frames of structural members to form an outer wall portion of a building, the curtain wall system having at least one connector device securing one of the glazing panels to one of the frames of structural members, the connector device comprising a keeper secured to any one of the frame and the sash, and a latch mechanism secured opposite the keeper on the other of the frame and the sash, the latch mechanism having a latch bolt automatically displaceable to a locking position upon contact with the keeper, the keeper and the latch mechanism cooperating in said locking position to lock the glazing panel to the frame in a secured position. 
     Further in accordance with the present invention, there is provided a method for installing a curtain wall portion to a building frame, comprising the steps of: i) providing structural members; ii) providing glazing panels and positioning second connection members on a sash of the glazing panels; iii) installing the structural members to a building framing so as to define frames adapted to support glazing panels; iv) automatically securing the glazing panels to frames by inserting the glazing panels within the frames, whereby the first connection members and the second connection members cooperate to lock the glazing panels to the frames; and v) forcing the second members into a blocked position. 
     Still further in accordance with the present invention, there is provided a curtain wall system comprising structural members secured to the building framing to define frames, glazing panels each having a sash by which the glazing panels are secured to the frames of structural members to form an outer wall of a building, and connector devices securing the glazing panels to the frames of structural members, the connector device having a keeper secured to any one of the frame and the sash of the glazing panel, a latch mechanism secured opposite the keeper on the other of the frame and the sash, the latch mechanism having a latch bolt automatically displaceable to a locking position upon contact with the keeper, the keeper and the latch mechanism cooperating in said locking position to lock the glazing panel to the frame in a secured position. 
     Still further in accordance with the present application, there is provided a connector device for a curtain wall system having structural members secured to the building framing to define frames to support glazing panels, the glazing panels each having a sash by which the glazing panels are secured to the frames of structural members to form an outer wall portion of a building, the curtain wall system having at least one of the connector device securing one of the glazing panels to one of the frames of structural members, the connector device comprising: a keeper adapted to be secured to the frame; and a latch mechanism adapted to be secured on the sash opposite the keeper, the latch mechanism comprising a latch bolt in a casing, a spring biasing the latch bolt to a projecting position with respect to the casing, and a pin having an interference head extending from a rear end of the latch bolt, the latch bolt having a ramp surface and an abutment surface at a front end thereof, the latch bolt in the projecting position being aligned with respect to the keeper for the ramp surface to contact the keeper when installing the sash in the frame, the latch bolt retracting from the projecting position in a retracting direction as a result of the contact between the keeper and the ramp surface, the latch bolt returning to the projecting position when the ramp surface is beyond the keeper by movement in a projecting direction, the keeper and the abutment surface of the latch mechanism in said projecting position cooperating beyond the keeper to retain the glazing panel to the frame, the interference head blocked by interference into the casing when forced toward the projecting direction into engagement with the casing to block the latch bolt from a projecting position into a locking position. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which: 
         FIG. 1  is a cross-sectional top view of a curtain wall system in accordance with the prior art; 
         FIG. 2  is a cross-sectional top view of a curtain wall system in accordance with a preferred embodiment of the present invention; 
         FIG. 3  is a perspective view of a connection device as used in the curtain wall system of  FIG. 2 ; 
         FIG. 4  is a perspective view illustrating a glazing panel in the process of being secured to a structural member for the curtain wall system of  FIG. 2 ; 
         FIG. 5  is a perspective view illustrating the glazing panel secured to the structural member for the curtain wall system of  FIG. 2 ; and 
         FIG. 6  is a cross-sectional top view of the curtain wall system of  FIG. 2 , with a latch bolt in forced engagement with the structural member. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to the drawings and, more particularly, to  FIG. 1 , a curtain wall system in accordance with the prior art is generally shown at  10 . The curtain wall system  10  is part of a VEC facade. Accordingly, each glazing panel  11  has a glass panel  12  and sash members  13  projecting away from a rear surface of the glass panel  12 . The sash members  13  are provided so as to secure the glazing panel  11  to the mullions M (one of which is shown in  FIG. 1  and is also known as an upright) and transoms (i.e., crosspieces). 
     The sash members  13  are secured to a rear surface of the glass panel  12 , whereby glass panels  12  of adjacent glazing panels  11 , as shown in  FIG. 1 , are not separated by structural members as is the case with traditional curtain wall systems. 
     Adjacent glazing panels  11  are spaced by a gap  14 , which gap  14  is partially blocked from water/air infiltration by gaskets  15 . The sash members  13  and the mullion M are accessed through the gap  14 . It is therefore through the gap  14  that fasteners, such as screws, bolts or the like, are inserted to secure the glazing panel to the mullions M, and transoms or other structural members of curtain walls. 
     Referring to  FIG. 2 , a curtain wall system in accordance with a preferred embodiment of the present invention is generally shown at  20 . The curtain wall system  20  has glazing panels  21 , each having a glass panel  21 A (or translucent/transparent panel of like material). Sash members  22  form a polygonal frame (i.e., rectangular frame in most instances) that is secured to and projects from a rear surface of the glass panel. The sash of sash members  22  is used to secure the glazing panels  21  to the structural members about the periphery of the glazing panels  21 , such as mullions M (one of which is shown in  FIG. 1 ), and transoms. 
     Each of the sash members  22  is typically constructed of extruded members  23 . The extruded members  23  define various channels, such as channel  24 , to receive gaskets (not shown) or like sealing devices. Connection fingers  25  are also provided, whereby cover plates, such as cover plate  26  can cover the extruded members  23 . This will be described in further detail hereinafter. 
     As mentioned previously, traditional glazing curtain wall systems involve the use of threaded fasteners or the like to secure the glazing panels to associated structural members. In order to simplify the interconnection between the glazing panel  21  and the structural members of the curtain wall system (e.g., mullion M), a connection device  30  is provided, as shown in  FIGS. 2 and 3 . 
     The connection device  30  uses cooperating connection members, such as a latch mechanism  31 , and a keeper  32  formed in associated structural members. In a preferred embodiment of the present invention, as shown in  FIG. 2 , the latch mechanism  31  of the connection device  30  is secured to the sash members  22 , whereas the keeper  32  is extruded with the structural members, such as the mullion M or transoms. Although not illustrated and described, it is also contemplated to position the latch mechanism  31  in the structural members with the keepers  32  in the sash members  22 . 
     Referring concurrently to  FIGS. 2 and 3 , the latch mechanism  31  has a latch bolt  33  in a casing  34 . The latch bolt  33  has a ramp surface  33 A and an abutment surface  33 B. The casing  34  is tubular, and the latch bolt  33  is partially accommodated within the casing  34 , and projects out of a first end of the casing  34 . A pin having a pin head  35  projects away from latch bolt  33 , such that the pin head  35  protrudes out of the second end of the casing  34 . In the illustrated embodiment of  FIG. 3 , the pin is a bolt, and the pin head  35  has a plurality of longitudinal fins  35 A. 
     A biasing member  36  (i.e., a spring) biases the latch bolt  33  to the projecting position illustrated in both  FIGS. 2 and 3 . The latch bolt  33  is retractable within the casing  34  against the force of the biasing member  36 . 
     In  FIG. 2 , the keeper  32  is shown as an extruded projection of the mullion M. The keeper  32  has a protrusion  40  that will cooperate with the latch bolt  33  to secure the glazing panel  21  to the structural members. The protrusion  40  has a ramp surface  40 A and an abutment surface  40 B. 
     Now that the connection device  30  has been described, an installation of the glazing panel  21  using the connection device  30  is described. 
     Only one connection device  30  is visible from the illustrations of the curtain wall system  20  of  FIGS. 2 ,  4  and  5  (with the glass panel removed from  FIGS. 4 and 5  for the simplicity of the illustration). However, it is contemplated to provide a plurality of the connection device  30  about the periphery of the sash of sash members  22  and of the corresponding frame of structural members (i.e., mullions M and transoms). In doing so, a plurality of latch mechanisms  31  interact with the keepers  32 . 
     Referring to  FIG. 4 , the glazing panel  21  is brought into a corresponding opening defined by the structural members (such as the mullion M), in a direction represented by A. When the latch bolt  33  comes into contact with its associated keeper  32 , the latch bolt  33  retracts into the casing  34  by the action of the ramp surfaces  33 A and  40 A contacting each other. 
     When the glazing panel  21  is in position within the frame of structural members, the latch bolt  33  has been biased back to its projecting position, as illustrated in  FIGS. 2 and 5 . Accordingly, the abutment surfaces  33 B and  40 B are coplanar, such that the glazing panel  21  is locked to the structural members (e.g., the mullion M). The latch bolt  33  is further engaged into connection with the keeper  32 , by forcing the fins  35 A into the casing  34  (e.g., force fitting). This is preferably done by hammering on the head  35 . Accordingly, a contact surface between the abutment surfaces  33 B and  40 B is increased, while an interference engagement is caused between the head  35  and the casing  34 , whereby the latch bolt  31  is blocked in the locking position. 
     Various seals or gaskets are provided against water/air infiltration through the curtain wall system  20 . One of these gaskets is generally shown at  41 , and is squeezed between the sash member  22  and the mullion M. Although only one gasket is illustrated for clarity of the illustrations, it is pointed out that a plurality of gaskets are typically used with the curtain wall system  20 . 
     Therefore, the curtain wall system  20  of the preferred embodiment of the present invention facilitates the installation of glazing panels  21  to the structural members, in that the connection devices  30  clip the glazing panel  21  into secured position within the frame formed of structural members. It is contemplated to provide a plurality of the connection devices  30 , such that no other types of fasteners are required in securing the glazing panel  11  to the frame of structural members. Alternatively, a combination of the connection device  30  and threaded fasteners can be used. 
     In order to remove the glazing panel  21  from the frame of structural members, the latch bolt  33  is retracted within the casing  34  until the abutment surfaces  33 B and  40 B no longer interfere with one another. The latch bolt  33  is retracted within the casing  34  by pulling onto the pin head  35 . In instances in which a plurality of connection devices  30  are provided to secure the glazing panel  21  to the frame of structural members, it is contemplated to provide a wedge (not shown) that will keep the latch bolt  31  retracted in the casing  34 . 
     It is pointed out that the pin heads  35  are oriented toward an interior of the building. Accordingly, the connection devices  30  are unlocked from an interior of the building. 
     Referring to  FIG. 6 , it is seen that very little clearance is provided between the pin head  35  and the cover plate  26 . Accordingly, if the latch bolt  33  is not in its projecting position (as illustrated in  FIGS. 2 and 3 ), the pin head  35  will prevent the cover plate  26  from being installed, and this can be interpreted as an indication that the glazing panel  21  is not fully secured to the frame of structural members. The latch bolts  33  must therefore be hammered into forced engagement with the keeper  32 , as described above, for the cover plate  26  to be installed. 
     The amount of installation time for the curtain wall system  20  is therefore relatively low. For instance, workers do not need to maintain the glazing panel against the frame of structural members, as the connection devices  30  will automatically lock the glazing panel  21  into position in the frame of structural members. Also, as fasteners no longer need to be inserted between adjacent glazing panels in some instances, the gap between adjacent glazing panels can be reduced. This results in an enhanced esthetic appeal to the curtain wall system  20 . Moreover, the release member constituted by the pin head  35  enables the removal of a glazing panel from a frame of structural members. It is also contemplated to provide set screws or similar equipment on the sash of sash members  22 , to allow an adjustment of the position of the glazing panel  21  with respect to the frame of structural members. This adjustment is performed once the glazing panel  21  has been engaged into the frame of structural members. 
     It is within the ambit of the present invention to cover any obvious modifications of the embodiments described herein, provided such modifications fall within the scope of the appended claims.

Summary:
A connector device is provided for a curtain wall system of the type having structural members secured to the building framing to define frames to support glazing panels. The glazing panels each have a sash by which they are secured to the frames of structural members to form an outer wall portion of a building. The curtain wall system has connector devices securing one of the glazing panels to the frames of structural members. The connector device comprises a keeper secured to a frame, and a latch mechanism secured opposite the keeper on the sash. The latch mechanism has a latch bolt automatically displaceable to a locking position upon contact with the keeper. The keeper and the latch mechanism cooperate in the locking position to lock the glazing panel to the frame in a secured position. A method for installing the connector device is also provided.