Patent Publication Number: US-7213375-B2

Title: Sealed glazing units

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to sealed glazing units spaced apart by a perimeter seal, to methods for the construction of such units and to fixing assemblies which are useful in these novel units and methods. 
   Suspended assemblies comprising a plurality of sealed double glazing units spaced apart by a perimeter seal (so-called frameless glazing units) mounted edge to edge so as to provide the appearance of a solid glass wall are increasingly used in buildings. GB 2171137 describes such assemblies comprising an array of double glazed units each of which comprises a fixing assembly which is attached to one of the panes in a manner which allows the unit to flex without impairing the seal of the unit. 
   The known frameless systems are all based upon double glazed units. As building regulations become more stringent the performance of these units especially their heat retention properties may be less than is required by regulation or desired by the architect. One method of improving the heat retention properties of conventional framed windows is to replace double glazed units with triple glazed units. However the design of a triple glazed frameless glazing unit is complicated by the need to support the additional weight of a third pane and by the need to ensure that the glazing does not fail under wind load. 
   SUMMARY OF THE INVENTION 
   We have now discovered that these problems may be overcome by attaching a fixing assembly so as to share the load between the inner and the outer pane and sealing the air spaces within the unit. 
   Thus from a first aspect this invention provides a sealed multiple glazing unit comprising at least three panes spaced apart from one another by a perimeter seal and having at least one fixing position within the perimeter seal at which fixing position there is a fixing assembly which is attached to the inner and the outer panes and which passes through a sealed hole in the centre pane. 
   The seal between the air spaces in the unit need not be completely airtight. However in the preferred embodiments that seal is a hermetic seal. Any passage of air between the two air spaces reduces the heat retention properties of the unit. Furthermore if the seal is airtight when the outer panes flex under wind load the air is compressed and transmit force to the inner panes causing them to flex and reducing the likelihood of two panes in the unit coming into contact. 
   The fixing assembly will preferably comprise a bush, a boss, a fixing member and a locking nut which engages the fixing member. A hole is drilled through each pane to define a fixing position. Such holes are normally circular and the boss is preferably of a generally cylindrical shape. The boss may be formed as a single component or from two components which interlock to form the boss. 
   Preferably the boss comprises two interlocking components having opposed faces which engage the faces of the centre pane thereby helping to retain that centre pane in position. A sealing ring formed from a suitable material such as nylon, neoprene rubber or a silicone rubber may be located on each of these opposed faces thereby sealing the centre pane. 
   Fixing assemblies wherein the boss comprises two interlocking pieces are believed to be novel and thus from another aspect this invention provides a fixing assembly for a sealed glazing unit comprising at least three panes said assembly comprising a boss, and a fixing member passing through said boss which is characterised in that the boss is formed from two interlocking components. In a preferred embodiment the boss is characterised in that the two interlocking components have opposed faces which are adapted to engage the surfaces of a glass pane when the components are interlocked. 
   Usually the sealed units are rectangular with a fixing position in the region of each corner. Preferably the fixing assembly is clamped to the innermost pane of the unit, more preferably it is also clamped to the outermost pane of the unit and most preferably it is also clamped to the centre pane. The holes in the innermost and in the outermost panes through which the fixing assembly passes must be hermetically sealed so as to preserve the integrity of the unit. The holes in the centre pane are preferably hermetically sealed so as to isolate the two air spaces within the unit from each other. 
   In those preferred embodiments where the fixing assembly is clamped to the panes of the unit, the unit may be sealed by providing a sealing ring on those surfaces of the assembly which are in contact with the pane. Conveniently this sealing ring may be an O ring located in an annular groove in that surface which protrudes slightly above that surface. The sealing ring may be formed from a variety of compressible materials such as nylon, silicone rubber or neoprene rubber. When the unit is assembled these rings are compressed and form a seal. In a more preferred embodiment this seal is supplemented by a secondary seal formed by filling the gaps between the contact surfaces of the assembly and the panes of the unit with a secondary silicone sealing compound. 
   A variety of fixing members have been used as part of the fixing assemblies used in existing frameless double glazing units. Any of these fixing members are potentially useful in the triple glazed units of this invention. The preferred classes of fixing member useful in the units of this invention include fixing bolts of the type described in UK patent GB 2171137 having a countersunk head which engages a countersunk hole in the outer surface of the outer pane. Also useful are fixing bolts of the type described in U.S. Pat. No. 4,793,112 having a countersunk head which engages a countersunk hole in the inner glass of a laminated outer pane. A third type of fixing member is described in European Patent EP 201212 comprising a ball member and a socket member wherein the socket is secured in a hole in the outer pane and the ball member is an elongate member which extends through the unit. 
   The fixing member is fixed to a supporting member which is attached to a building. Typically the supporting member may be a spring plate member. The provision of an array of supporting members on a building enables a corresponding array of glazing units to be mounted on that building usually in edge to edge relationship so as to provide the appearance of a solid glass wall. Assemblies comprising an array comprising the novel units provide a further aspect of the present invention. 
   The units of this invention preferably comprise three glass panes. Most commonly soda lime float glass having a thickness of from 2 to 20 mm and more preferably from 4 to 12 mm will be employed. Where the glass is load bearing toughened glass will preferably be used. In that instance the holes in the glass must be drilled prior to the toughening process. Glass panes having a low emissivity coating on at least one surface may also be utilised. Laminated glass may also be employed in particular as the outer pane. In a preferred embodiment the fixing assembly is located in the outer pane in a housing cut into the inner sheet of the laminate. The outer sheet of the laminate provides an uninterrupted surface when viewed from outside the building which may be aesthetically pleasing. The outer sheet of such a laminate may also be formed from decorated or patterned glass to provide a particular external appearance. Body tinted glasses may also be used to provide a unit having a particular appearance. 
   Panes formed from clear plastic materials such as polycarbonates may also be employed in the units of this invention. These plastic panes may replace some or all of the glass panes. In the preferred embodiments at least the outermost pane and more preferably both the innermost and the outermost panes are glass panes. Where a plastic pane is used it is preferably used to form the centre pane where the surface of the plastic is protected against scratching. 
   The thickness of the panes in each unit need not be identical. Each pane should be sufficiently thick and thereby sufficiently strong to withstand the load which is to be placed upon it. However the use of excessively thick panes is not desirable because of the consequent increase in the size and weight of the unit. 
   The heat retention properties of the units of this invention (expressed as a U value in units of W/m 2 K) are preferably less than 3.0, more preferably less than 2.0 and most preferably less than 1.0. The U value of any unit is determined by a number of factors including the thickness of the panes, the distance between the panes and the presence of a heat reflecting coating on at least one surface of the glass and the position of that coating in the unit. Where a coated glass is used to improve the U value of the unit it is preferably located on surface  3  of the unit (that is on the outer surface of the centre pane using the conventional nomenclature numbering the outer surface of the outer pane as surface 1 and the inner surface of the outer pane as surface  2  etc.). 
   The units of this invention may be assembled by fitting a bush into a countersunk hole in the outer pane and locating the boss in the bush so that it is in contact with the interior surface of the outer pane. A spacer bar carrying a primary butyl sealant is then fitted around the perimeter of the pane. The centre pane is then fitted over the boss and presented so as to engage the spacer bar. The centre pane is held loosely in place by adhesion to the primary butyl sealant. A second spacer bar is then fitted around the perimeter of the centre pane and the inner pane is fitted over the boss and held loosely in place by adhesion to the primary butyl sealant. The entire unit can then be compressed to form the seals. 
   This assembly operation requires that the holes in the centre and inner panes be large enough to accommodate the boss. Since the diameter of the boss will be larger than the hole in the outer pane the boss may be tapered in order to permit the use of panes having holes with a smaller diameter which may be the same or a similar diameter to the hole in the outer pane. Such a boss comprises two portions one having a smaller diameter than the other. The hole in the centre pane is of a size as will fit over the smaller portion of the boss but not over the larger part. The centre pane is thereby located on the fixing assembly. The bottom portion of the boss may also be tapered in a similar fashion so that the inner pane fits over the tapered portion and is thereby located on the fixing assembly. 
   In the preferred embodiments of this invention the boss comprises two components which interlock to form the boss. These preferred units may be assembled using a variation of the above procedure which permits the use of panes having holes of an identical size and facilitates the sealing of the boss within the hole in the centre pane. 
   These two part bosses comprise two component parts each of which is in contact with the inner surface of either the outermost pane or the innermost pane and with the opposed surface of the centre pane. Preferably each part of the boss has an extension which passes through the hole in the centre pane said extensions interlocking one with the other to form the boss. The boss also preferably extends through the hole in the innermost pane but does not protrude beyond that pane. 
   The extensions which pass through the hole in the centre pane may conveniently take the form of hollow cylinders, the internal diameter of one being substantially the same as the external diameter of the other. The length of these extensions is such that they overlap each other and interlock with each other by virtue of the extension with the smaller external diameter forming a push fit with the extension having the larger external diameter. 
   The extension with the larger external diameter preferably has a diameter which is slightly less than the diameter of the hole in the centre pane. In the preferred embodiments the extension with the larger external diameter is part of that portion of the boss which is in contact with the inner surface of the outer pane of glass. Any part of the boss which extends through the hole in the inner pane preferably has a diameter which is slightly less than the diameter of the hole. In these preferred embodiments the slight differences between the diameters of the extensions and the diameters of the holes in the panes facilitates the assembly of the units. Further the space between the side of the extensions and the edge of the glass can be filled with a secondary silicone sealant which improves the seal between the boss and the centre glass. 
   In the preferred embodiments of the invention those surfaces of the boss which are in contact with the panes of the unit are provided with a secondary silicone sealant in addition to the primary sealing ring. The surface is provided with an annular groove in which the silicone may be located. Preferably the grooves are interconnected and are provided with an inlet passage through which silicone may be injected and an outlet passage through which air displaced by the sealant may escape. The inlet passage may connect to the interior passage of the boss so that (prior to the fixing member being inserted into that passage ) a suitable injector may be connected to the inlet passage and silicone injected through that passage. The passage through which the sealant may pass should be designed so as to avoid in so far as is possible the entrapment of air bubbles within the passage. Where the boss is formed from two interlocking components the components should be provided with locating means so as to fix their relative positions and ensure that the passage through which the sealant may be injected is not interrupted. The interlock between the two portions of the boss should be such that sealant does not enter the gap between the two portions. 
   These two component bosses also facilitate the assembly of the units using a novel method which is a variant upon the one described above. These methods comprise the steps of (a) fitting a bush into a countersunk hole in the outer pane; (b) locating a first component part of the boss in the bush so that it is in contact with the interior surface of the outer pane; (c) fitting a spacer bar around the perimeter of said outer pane; (d) fitting the centre pane onto the first component part of the bush; (e) locating the second component part of the boss so that it interlocks with the first component part of the bush; (f) fitting a spacer bar around the perimeter of said centre pane; (g) locating the inner pane so that it is in contact with the surface of the second component part of the boss and (h) compressing the unit. In a preferred embodiment the centre pane is located upon the extension of the first component part of the boss and the second component part of the boss is interlocked with the first part by engaging an extension thereof with that extension of the first part 

   
     In the more preferred embodiments the method comprises an additional step (i) wherein a secondary silicone sealant is injected through an inlet passage into the spaces between the panes and the surfaces of the boss which are in contact with those panes. One embodiment of the invention will now be described with reference to the accompanying drawing. 
       FIG. 1  is a part sectional view of a triple glazed unit according to the invention wherein the space between the outermost pane of glass and the centre pane of glass is hermetically sealed from the space between the centre pane of glass and the inner pane of glass and showing in detail a fixing assembly comprising a two part boss. 
       FIG. 2  is a part sectional view of a triple glazed unit according to the present invention utilising a tapered boss. 
       FIG. 3  is a part sectional view of a triple glazed unit according to the present invention utilising a cylindrical boss which is a close fit within a hole in the centre pane. 
   

   As shown in  FIG. 1  the units comprise an outer pane  1 , a centre pane  3  and an inner pane  5 . Outer pane  1  has a hole  7  having a countersunk portion  9  adjacent to its outer face. Centre pane  3  has a circular hole  11  and inner pane  5  has a circular hole  13 . Holes  7 ,  11  and  13  are aligned along a common axis. Fixing bolt  15  passes through holes  7 ,  11  and  13  and lies along their common axis. The countersunk head of fixing bolt  15  engages washer  17  and bush  19  in hole  7  and lies flush with the outer surface of outer pane  1 . 
   Outer boss  21  is of generally cylindrical form. The upper surface of the outer boss  21  engages the inner face of the outer pane  1  and the lower surface of the outer boss  21  engages the upper surface of the centre pane  3 . The upper part of the outer boss  21  engages bush  19 . The lower portion of the outer boss comprises an extension  23  which passes through hole  11  and lies flush with the interior face thereof. 
   Inner boss  25  is also of generally cylindrical form. The upper surface of the inner boss  25  engages the lower surface of the centre pane  3  and the lower surface of the inner boss  25  engages the inner face of the inner pane  5 . Inner boss  25  comprises an upper extension  27  which extends through hole  11  in the centre pane and is a snug fit with extension  23 . The inner boss  25  also extends through hole  13  in the inner pane and lies flush with the outer face thereof. 
   The upper and lower surfaces of both the outer boss  21  and the inner boss  25  have annular grooves  31 ,  33 ,  35  and  37  machined into them. These grooves provide a seating for sealing O rings  39 ,  41 ,  43  and  45 . 
   The upper and lower surfaces of both the outer boss  21  and the inner boss  25  have second annular grooves  47 ,  49 ,  51  and  53  machined into the surface thereof. These grooves accommodate a silicone sealant. Outer boss  21  has a bore  55  connecting groove  47  to the interior of the boss. At a point approximately diametrically opposite bore  55  a passage  57  connects grooves  47  and  49 . Passage  59  between the extension  27  of the outer boss  21  and the edge of the centre pane  3  connects groove  49  with groove  51 . Passage  61  connects grooves  51  and  53  at point approximately diametrically opposite passage  57 . Bore  55 , groove  47 , passage  57 , groove  49 , passage  59 , groove  51 , passage  61  and groove  53  define a pathway through which silicone sealant can be injected into the glazing. The positioning of passage  61  diametrically opposite passage  57  ensures when the sealant is injected through bore  55  it enters groove  49  through passage  57  and then passes around both sides of the annular grooves  49  and  51  and the annular passage  59  before it can enter passage  61   
   Washer  63  fits on flanged spigot  67  and lies against the inner surface of the flange which provides a seat for washer  63 . Nut  65  is tightened onto fixing bolt  15  to clamp the unit together. The fitting  69  extends into the interior of the boss to provide further support for the unit. The fitting is mounted onto the wall of a building using any of a variety of known fixings. 
   The units of this embodiment of the invention may be assembled using the following novel method. The outer pane  1  is fitted with bush  19  and the outer boss  21  is engaged with bush  19  and brought into contact with the interior face of outer pane  1 . A spacer bar is then fitted around the perimeter of the pane  1 . Centre pane  3  is then positioned upon extension  23  of the outer boss  21 . The centre pane engages the spacer bar and is held loosely in place by adhesion to the primary butyl sealant present on that spacer bar. The inner boss  25  is then pushed into position such that extension  27  interlocks with extension  23  of the outer boss. A second spacer bar is then fitted around the perimeter of the centre pane. The inner pane  5  is then positioned on the inner boss  25  with its interior surface in contact with the lower surface of the boss. The inner pane  5  is held loosely in place by adhesion to the primary butyl sealant present on the spacer bar. The entire unit may then be compressed so as to bring the inner and outer portions of the boss  21  and  25  and the panes  1 ,  3  and  5  into closer alignment. Thereafter a suitable injector may be introduced into the interior of the boss and the secondary silicone sealant is injected into bore  55 . The injection of sealant is continued until the sealant is seen to fill and emerge from hole  13 . The unit may then be left to allow the secondary sealant to cure. Such units may be sold as articles of commerce and as such comprise a further aspect of this invention. 
     FIG. 2  shows a unit comprising an outer pane  1 , a centre pane  3  and an inner pane  5 . Fixing bolt  15  passes through holes  7 , 11  and  13  and lies along their common axis. The countersunk head of fixing bolt  15  engages washer  17  and bush  19  and lies flush with the outer surface of the outer pane  1 . 
   Boss  20  is of generally cylindrical form. The upper surface of boss  20  engages the inner face of the outer pane  1 . The lower surface of boss  20  engages the upper surface on inner pane  5 . The boss  20  is tapered to provide a surface  22  which engages the outer face of the centre pane  3 . The upper and lower surfaces of boss  20  have annular grooves  32  and  34  machined into them. These grooves provide a seating for sealing O rings  40  and  42 . Silicone sealant is injected into annular gap  44  between the edge of centre pane  3  and boss  20  and also into the annular gap  46  between the edge of the inner pane  5  and boss  20 . 
   Washer  63  sits on flanged spigot  67  and lies against the inner surface of the flange which provides a seat for washer  63 . Nut  65  is tightened onto fixing bolt  15  to clamp the unit together. The fitting  69  extends into the interior of the boss to provide further support for the unit. 
     FIG. 3  shows a unit comprising an outer pane  1 , a centre pane  3  and an inner pane  5 . Fixing bolt  15  passes through holes  7 ,  11  and  13  and lies along their common axis. The countersunk head of fixing bolt  15  engages washer  17  and bush  19  and lies flush with the outer surface of the outer pane. 
   Boss  22  is of generally cylindrical form. The upper surface of boss  22  engages the inner face of the outer pane  1 . The lower surface of the boss  22  engages with the upper surface of the inner pane  5 . The upper and lower surfaces of boss  22  have annular grooves  36  and  38  machined into them. These grooves provide a seating for sealing O rings  40  and  42 . 
   The upper and lower surfaces of boss  22  have second annular grooves  48  and  50  machined into them. Passage  56  connects grooves  48  and  50 . Bore  56  connects groove  47  to the interior of the boss. 
   Centre pane  3  is held in position by the perimeter seals (not shown) between the outer pane  1  and the centre pane  3  and between the inner pane  5  and the centre pane  3 . Centre pane  3  is a close fir around boss  22  so as to reduce the passage of air between the air spaces in the unit to an acceptable level. 
   Washer  63  sits on flanged spigot  67  and lies against the inner surface of the flange which provides a seat for washer  63 . Nut  65  is tightened onto fixing bolt  15  to clamp the unit. The fitting  69  extends into the interior of the boss  22  to provide further support for the unit. 
   The units of  FIGS. 2 and 3  may be assembled using processes analogous to those described in relation to  FIG. 1 . 
   These units may be transported to the building to which they are to be attached. At that point the fixing bolt is fitted through the boss to complete the fixing assembly and engaged with the locking nut so as to complete the fixing assembly. The unit is itself mounted upon the building.