Abstract:
A curtain wall system having a framing of mullions and transoms. The mullions have a mullion body portion and a mullion nose portion and spaced notches in the mullion body portion. The penetrating transom have a transom body portion and a transom nose portion. The transom nose portion has extensions extending beyond opposed ends of the transom body portion received in the notches of the mullion body portions whereby the framing portion is formed for sealing receiving a panel to form an air barrier, with a gap being defined between the extensions of the transoms and the mullion nose portions. Pressure plates are connected to the mullions and transoms to form a sash with the framing portion so as to secure the panels within the sash. A seal member blocks each gap to form a pressurized cavity with the sash about the glass panel.

Description:
TECHNICAL FIELD 
   The present invention generally relates to curtain wall systems and, more particularly, to a connection between structural members of the curtain wall in a rain-screen type of curtain wall system. 
   BACKGROUND ART 
   Curtain walls are widely used as exterior sheathing of buildings, especially of the commercial or institutional type. Curtain walls consist of glass panels constituting a major portion of the exterior surface of the building, with structural members separating the glass panels. 
   The structural members typically form a grid consisting of mullions (i.e., vertical members) and transoms (i.e., horizontal members). Panels are sealingly received between sets of mullions and transoms and supported thereby, so as to define the exterior sheathing of the building. In a rain-screen type of curtain wall system (zone drainage system), the framing about each glass panel defines a cavity between inner structural members and outer structural members. The inner structural members form a rain screen with the glass panel. The pressurized cavity between the inner and outer structural members defines a pressure zone of a pressure generally equal to that exerted on the outer structural member. The pressurized cavity is ventilated so as to allow air to enter or exit the cavity, in order to equalize the pressure in the cavity to the pressure at the exterior of the curtain wall. Accordingly, pressure increases, for instance due to wind or like atmospheric conditions, will be neutralized by the pressure zone and thus not cause infiltration through the rain screen. 
   However, curtain wall systems are still subject to water/air infiltration. Water/air infiltration through structural members is often through the intersection between the transoms and the mullions. More specifically, according to the type of construction of the mullions and the transoms, a caulking joint is often made between interconnected pieces. The caulking joint between the adjacent pieces seals off interface between interconnected pieces and is responsible for the water/air tightness of the curtain wall. 
   The efficiency of the tightness is related to the quality of joint being made between the interconnected structural members. As the sealing joints are made manually, and are exposed to great temperature variations and severe weather conditions, the water/air tightness of curtain wall systems is often inadequate such that there is infiltration. 
   Other constructions of structural members for curtain walls include a protrusion at ends of the transoms, which protrusions are received in corresponding notches in the mullions and are referred to as “penetrating transoms”. For instance, U.S. Patent Application No. 2004/0031220, by Hocker et al. and as published on Feb. 19, 2004 illustrates this type of configuration. The interconnection between the penetrating transom and the mullion reduces the risk of infiltration through the interface between the transoms and mullions. 
   In such systems, water collected by the transoms is drained by the effect of gravity and by the draining configuration of the structural members. More specifically, the transoms are positioned such that water accumulated thereon is drained toward the mullions. Accordingly, vertically adjacent sashes formed of structural members around a panel must be in fluid communication with one another so as to allow drainage of water on the surface of the mullions. Therefore, it is difficult to maintain a pressure equalization between the sash of a panel (i.e., a zone) and the surrounding pressure as all sashes communicate with one another. At present, systems with penetrating mullions are not used in rain-screen type of curtain wall systems due to the absence of isolated pressurized cavity about each panel. 
   SUMMARY OF INVENTION 
   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 which addresses the above issues. 
   Therefore, in accordance with the present invention, there is provided a curtain wall system of the type having a framing of mullions and transoms adapted to support panels, the curtain wall system comprising: framing portions for supporting the glass panels, each framing portion being formed by: a pair of horizontally spaced apart mullions, each said mullion having a mullion body portion and a mullion nose portion projecting from the mullion body portion, a pair of vertically spaced notches in the mullion body portion; and a pair of vertically spaced apart penetrating transoms, each said penetrating transom having a transom body portion and a transom nose portion projecting from the transom body portion, the transom nose portion having extensions extending beyond opposed ends of the transom body portion, the extensions being received in the notches of the mullion body portions such that the penetrating transoms are supported by the mullions, whereby the framing portion is formed for sealing receiving a panel to form an air barrier, with a gap being defined between the extensions of the transoms and the mullion nose portions; pressure plates connected to the mullion nose portions and to the transom nose portions to form a sash with the framing portion so as to secure the panel within the sash; and a seal member blocking each said gap to form a pressurized cavity with the sash about the glass panel, whereby a rain screen is formed by the combination of the air barrier and the pressurized cavity. 
   Further in accordance with the present invention, there is provided a curtain wall system of the type having a framing of mullions and transoms adapted to support panels, the curtain wall system comprising: framing portions for supporting the panels, each framing portion being formed by: a pair of horizontally spaced apart mullions, each said mullion having a mullion body portion and a mullion nose portion projecting from the mullion body portion, a pair of vertically spaced notches in the mullion body portion and channels with longitudinal tapping in the mullion body portions; and a pair of vertically spaced apart penetrating transoms, each said penetrating transom having a transom body portion and a transom nose portion projecting from the transom body portion, the transom nose portion having extensions extending beyond opposed ends of the transom body portion, the extensions being received in the notches of the mullion body portions such that the penetrating transoms are supported by the mullions, whereby the framing portion is formed for sealing receiving a panel to form an air barrier; fasteners passing through the extensions to screwingly engage with the longitudinal tapping so as to secure the transoms to the mullions; and pressure plates connected to the mullion nose portions and to the transom nose portions to form a sash with the framing portion so as to secure the panel within the sash. 

   
     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 an exploded view of a rain-screen type of curtain wall framing in accordance with the prior art; 
       FIG. 2  is an exploded view of a mullion-drainage type of curtain wall framing in accordance with the prior art; 
       FIG. 3  is a perspective view of a sealing member used in a curtain wall framing in accordance with a preferred embodiment of the present invention; 
       FIG. 4  is an exploded view of the curtain wall framing in accordance with the preferred embodiment of the present invention; 
       FIG. 5  is a perspective view of the curtain wall framing of  FIG. 4 , without glass panels. 
       FIG. 6  is a cross-section view taken along cross-section lines VI-VI of the curtain wall framing of  FIG. 5 , with glass panels added; 
       FIG. 7  is a cross-section view taken along cross-section lines VII-VII of the curtain wall framing of  FIG. 5 , with glass panels added; and 
       FIG. 8  is a cross-section view of a mullion of the curtain wall framing of  FIG. 5 . 
       FIG. 9  is an assembly view, sectioned of framing portions of a certain wall in accordance with the preferred embodiment. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , a first type of curtain wall framing in accordance with the prior art is generally shown at  10 .  FIG. 1  shows an interrelation between a mullion  11  and a transom  12 . Both the mullion  11  and the transom  12  are extruded members, respectively provided with shoulders  13  and  14 , so as to support a glass panel (not shown) Pressure plates  15  and  16  respectively connect to the shoulders  13  and  14 , thereby defining a sash in which the glass panel is held captive. 
   The transom  12  is secured to the mullion  11  by connector bracket  17 . The connector bracket  17  is firstly secured to the mullion  11 , for instance using fasteners. The connector bracket  17  is thereafter accommodated within an inner cavity  11 A of the transom  11 . 
   In order to form an air barrier, the interface between the mullion  11  and the transom  12  is sealed by way of a sealing joint  17 A made between the connector bracket  17  and the mullion  11 . Accordingly, once a glass panel is received against the shoulders  13  and  14 , an air barrier will be created by the contact of the glass panel with the gaskets  19 , and by the sealing joint  17 A between the mullion  11  and the transom  12 . 
   In order to define a pressurized cavity about the glass panel, a sealing plug  18  is also provided and squeezed between the shoulders  13  and  14 . A sealing joint  18 A is made about the periphery of the sealing plug  18 . A pressurized cavity is therefore defined about each glass panel, and as such, the combination of the air barrier and of the pressurized cavity forms a rain screen. 
   Referring to  FIG. 2 , a mullion drainage type of curtain wall framing also in accordance with the prior art is generally shown at  20 .  FIG. 2  shows an interrelation between a mullion  21  and a penetrating transom  22 . Both the mullion  21  and the transom  22  are extruded members, respectively provided with shoulders  23  and  24 , so as to support a glass panel (not shown). Pressure plates (not shown) connect to the shoulders  23  and  24 , thereby defining a sash in which the glass panel is held captive. 
   As shown in  FIG. 2 , the mullion  21  defines a notch  21 A, in which an extension  22 A of the penetrating transom  22  is received. Fasteners (not shown) such as bolts or the like are used to secure the transoms  22  to the mullion  21 . 
   As opposed to rain-screen type curtain wall systems, water (e.g., rain received on the surface of the glass panels) is drained by the shoulders  24  of the transoms  22  in this type of curtain wall framing. The shoulders  24  of the transoms  22  are typically oriented so as to cause a drainage of water toward the mullions  21  (i.e., mullion drainage), as illustrated by A in  FIG. 2 . 
   The penetrating transoms  22  contact the mullions  21  on a pair of surfaces due to the configuration of the extension  22 A, and this results in lower water/air infiltration at the interface between the mullions  21  and transoms  22 . The interface between the mullions  21  and the transoms  22  is not directly exposed to winds. 
   Referring to  FIGS. 4 and 9 , a curtain wall framing in accordance with a preferred embodiment of the present invention is generally shown at  30 . The curtain wall framing  30  is similar to the curtain wall framing  20  of  FIG. 2 , in that mullions are notched for receiving extensions of penetrating transoms. However, the curtain wall framing  30  also provides zone drainage similarly to the rain-screen type of curtain wall system  10  of  FIG. 1 . 
   More specifically, a mullion  31  consisting of a body  31 B and a nose  31 C is shown having a notch  31 A, whereas a penetrating transom  32  consisting of a body  32 B and a nose  32 C is shown having an extension  32 A. The nose  31 C of the mullion  31  has a shoulder  33 , which is associated to a shoulder  34  of the nose  32 C of the penetrating transom  32 , so as to support a panel (e.g., glass panel). Pressure plates  35  and  36  are respectively secured thereafter to the mullion  31  and transom  32 , thereby defining a sash in which the glass panel (not shown) is held captive as is well illustrated in  FIG. 5 . Penetrating transoms  32  are supported by vertically spaced apart notches, with one level of notches  31 A illustrated in  FIG. 9 . 
   The curtain wall system  30  defines a rain screen that is substantially sealed from water/air infiltration. More specifically, gaskets  37 A are provided adjacent to the shoulders  33  and  34 , so as to contact the glass panel when the latter is received in the sash formed of mullions  31 , transoms  32  and pressure plates  35  and  36 . Moreover, by the penetration of the extension  32 A of the transom  32  in the notch  31 A of the mullion  31 , a generally watertight air barrier is formed by the framing  30  and the glass panel (not shown in  FIG. 4 ). A gap is defined between the extension  32 A and the body  31 B and nose  31 C of the mullion  31 . In the illustrated embodiment, the gap has an L-shaped geometry. 
   Similarly to zone drainage systems, the curtain wall system  30  defines pressure zone cavities about each glass panel, so as to reduce the risk of infiltration. In order to create a pressurized cavity for each glass panel, a sealing member  40  is provided, as shown in  FIGS. 3 and 4 . 
   Referring to  FIG. 3 , the sealing member  40  has a generally planar base  41 . Walls  42 A,  42 B and  42 C project from three sides of the periphery of the base  41 . A finger  43  extends from the wall  42 B, whereas a flange  44  projects from an opposed surface of the base  41 . A pair of through bores  45  extend through the base  41 . A pair of sealing ribs  46  is provided in the planar base  41 , and is generally parallel to the wall  42 B. It is pointed out that the through bores  45  are positioned between the ribs  46 . Sides  47  of the finger  43  are angulated. The sealing member  40  is preferably made of a polymeric material or like rubbery material, adapted to withstand temperature variations. 
   As seen in  FIGS. 3 and 7 , the distance between the walls  42 A and  42 C of the base  41  is such that a rear face  32 B of the extension  32 A is snugly accommodated within the depression formed by the base  41  and the walls  42 . Accordingly, the extension  32 A is received in the notch  31 A of the mullion  31  with the base  41  squeezed therebetween. 
   In order to form the pressurized cavity about the panel, the sealing member  40  is lodged in the gap between the mullions  31  and transoms  32 . 
   As seen in  FIGS. 4 and 6 , the finger  43  is sized so as to be sandwiched between the shoulder  34  of the transom  32  and the shoulder  33  of the mullion  31 . By way of the finger  43  squeezed between the shoulders  33  and  34 , the spaces between shoulders  33  and  34  are sealed off in view of forming a pressurized cavity about each glass panel  51 . Once the pressure plates  35  and  36  complete the sash about the glass panel  51 , gaskets  37 B ( FIGS. 4 to 7 ) contact the glass panel  51 . A pressurized cavity is therefore formed by the gaskets  37 A and  37 B. The cavity is sealed off, as mentioned previously, by the fingers  43  squeezed between the shoulders  33  and  34 . 
   In order to have the pressure within the pressurized cavity adapt to the outdoor pressure, air infiltration is permitted through the pressure plates  35  and  36 , as is known for rain-screen type curtain wall systems. Accordingly, a rain screen is formed by the combination of the air barrier and of the pressurized cavity. 
   As seen in  FIG. 6 , the flange  44  is received in a channel  50  of the mullion  31 . Through bores  32 D ( FIGS. 6 and 7 ) are preferably provided in the extension  32 A, and are positioned so as to be aligned with the through bores  45  in the sealing member  40 . The transoms  32  are secured to the mullions  31  by fasteners received in the through bores  32 D. Accordingly, in addition to the penetrating configuration, which minimizes infiltration, the member  40  accommodates the extension  32 A of the transom  32 , so as to reduce further the risks of infiltration at the interface between the mullions  31  and transoms  32 . The sealing ribs  46  prevent infiltration through the through bores  32 D. 
   Referring to  FIGS. 6 and 8 , the mullion  31  is shown having channels  52  in its inner cavity. The channels  52  are provided with longitudinal tapping, so as to cooperate with the fasteners used to secure the transoms  32  to the mullions  31 . This configuration advantageously allows for a worker to fasten the transoms to the mullions  31  from a frontal position, as opposed to the curtain wall framing of the prior art. 
   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.