Abstract:
A pressure equalization valve enabling equalization of pressure between the between-pane space of an insulating glass unit and ambient pressure, and glass units containing such a valve. The pressure equalization valve generally includes a valve body having a cavity therein and opposed, open ends and an elongated valve plug received in said valve body and securably shiftable along its length between plugged and unplugged configurations. The valve may be secured about an aperture in a glass pane. The valve body has a shoulder at one end, and the pane thickness is sandwiched between the shoulder and a washer preferably press-fitted to the other end of the body. The valve body cavity and the valve plug may include engaging threaded portions enabling the valve plug by rotation thereof to be shifted axially of the valve body between plugged and unplugged positions, the valve body and valve plug having engagable portions securing the plug against accidental escape from the body by axial, non-rotating movement of the plug.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to valves for equalizing pressure between two spaces of unequal pressure, and more particularly to a valve for equalizing the pressure between the enclosed space of an insulating glass unit and the ambient atmosphere. 
     2. Background of the Invention 
     Insulating glass units (“IG units”) have long been used in the building trades and other applications. Insulating glass units generally comprise at least two glass panes held in a generally parallel, spaced orientation by a peripheral spacer, the latter being joined to the sheets by a sealant. The space defined between the glass panes is hermetically sealed. High performance insulating glass is often manufactured using various technologies to improve energy efficiency, optical clarity and resistance to deterioration. The technology involving insulating glass units filled with a gas such as argon having a low coefficient of thermal conductivity is of particular interest. 
     Problems have been encountered with IG units carrying a gas such as argon in their between-pane spaces. Over a period of time, argon may slowly leak from the between-pane space to the atmosphere, and this generally occurs at a rate greater than the rate of permeation of air into the space, with the result that the pressure in the between-pane space reduced below atmospheric pressure. The resulting pressure differential causes the panes to cup inwardly, and the panes can eventually touch near their centers, with consequent loss of insulating value. In some cases, the cupping of the panes is so great as to cause one or the other of the panes to shatter. When failure occurs, the window units necessarily have to be replaced, and this can be extremely expensive in that the failed window unit must be removed and replaced with a new unit on a unit-by-unit basis. 
     Moreover, when IG units are transported to geographic locations of higher elevation and hence reduced atmospheric pressure, the panes of these IG units may bulge outwardly under the pressure differential across the panes, and this also causes distortion of the panes and may lead to ultimate glass breakage. 
     One possible remedy to this problem is to insert a valve in the insulating glass unit. A variety of valves or valve-like structures have been suggested to allow communication between the interior of insulating glass units and the ambient atmosphere. U.S. Pat. No. 4,567,703 (Ricks) discloses a spring-biased reusable valve intended to be opened over and over again whenever desired to equalize pressure between the interior of the insulating glass unit and the ambient atmosphere. U.S. Pat. No. 2,880,475 (Mills) discloses a self-sealing rubber valve. The Mills valve is designed to enable evacuation of the space between the panes of an insulating glass unit. The valve is configured similar to a duck bill valve, which accommodates the insertion of an exterior tube for release of interior pressure. U.S. Pat. No. 5,345,734 (Tremblay) discloses a plug to be inserted in the spacer at the periphery of an insulating glass unit. Once in place, the Tremblay plug is permanently sealed by the use of a plug similar in structure to a blind rivet. 
     Other examples of valve-like devices used in concert with insulating glass units are not truly valves at all in that they are designed to be sealed once and cannot be opened again under normal circumstances. Examples include U.S. Pat. No. 3,027,607 (Badger et al.), which discloses a metal insert to be embedded in the peripheral seal of the insulating glass unit to provide for gas injection and then to be permanently sealed with a bead of solder. 
     Additionally, U.S. Pat. No. 4,587,784 issued to Chavy et al discloses a structure similar to that of Badger that is intended to melt and release pressure within the IGU in the case of a structural fire. Under the heat of a fire, a fusible plug melts. Releasing increased pressure restrains the insulating glass unit from breaking. 
     U.S. Pat. No. 2,756,467 (Etling) shows the use of a hypodermic. needle passed through a sealant which forms a “self healing” seal when the needle is withdrawn. The Etling approach is intended to be used to evacuate the space within an insulating glass unit. 
     Finally, a number of prior art patents relate to the creation and sealing of pore holes which are intended to prevent the breakage of some types of insulating glass units in the manufacturing process. If an insulating glass unit is manufactured entirely of glass and the edges of the two panes are fused at their periphery, during the process of cooling the gases entrapped between the two panes contract dramatically creating a substantial possibility of breakage. Examples of a variety of pore holes and methods of sealing them are discussed in U.S. Pat. Nos. 2,784,462, 2,805,452, 2,887,737, 2,887,738, 2,894,294, 2,621,397, 2,886,864 and 2,755,521. 
     It would be desirable to be able manufacture an insulating glass unit, optionally containing an inert gas, such as argon, ship it to another location for further fabrication, storage or installation, and then have the capability to equalize the pressure in the insulating glass unit with the ambient atmosphere by either venting gas from the unit or allowing a gas such as air to enter the space between the panes. Furthermore, it would be desirable to be able to perform this function at anytime over the life of the insulating glass unit without undesired leakage occurring. Once pressure equalization is accomplished, it would be desirable to reseal the unit so as to prevent leakage of the entrapped gas. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a pressure equalization valve utilized to equalize the pressure inside an insulating glass unit with the outside atmosphere. The pressure equalization valve of the present invention may be applied to one of the panes of an insulating glass unit so that the pressure within the between-pane space of the insulating glass unit may be equalized with the exterior, ambient pressure as and when needed. 
     The pressure equalization valve generally comprises a valve body having a stem for passing through an aperture in a glass pane, the body having an internal cavity and opposed, open ends to allow a gas to flow through it and also having an enlarged shoulder at one end for sealing engagement with a glass pane about the periphery of the aperture. The valve includes a valve plug that is received in the cavity and that is securably shiftable axially along its length between a plugged position preventing gas flow through the valve body and an unplugged position enabling such gas flow. “Securably shiftable” means that the valve plug is prevented from accidentally escaping axially from the valve body when the plug is in its unplugged position. This feature is valuable in that it prevents the plug from being unintentionally removed or lost. 
     In a preferred embodiment, the internal cavity includes an internally threaded portion, and the valve plug includes an externally threaded portion that threadingly engages the internally threaded bore when the valve is in its plugged position. The plug further contains a second portion of lesser diameter but of greater axial length than the internally threaded bore of the valve body. Further, the valve plug preferably includes a third portion of a diameter preventing it from passing axially without rotation through the internally threaded bore. The lesser diameter second portion is intermediate the threaded first portion and the third portion such that when the first portion is unscrewed from the threaded bore, the space between the lesser diameter second, portion and the threaded bore provides a passageway for gas flow through the valve. Preferably, the third portion of the valve plug has exterior threads enabling it to be threadingly received in the threaded bore, thereby permitting the valve plug to be entirely unscrewed from the valve body. 
     The valve further preferably includes a washer assembly into which the end of the stem remote from its shoulder is received, the dimensions of the stem and the washer providing desirably for a secure press fit of the washer onto the system. 
     In the manufacturing process, an aperture is drilled through a glass pane, and the valve stem is inserted through the aperture from one side of the pane to bring the shoulder of the valve body into sealing engagement with the pane surface. The washer is received over the end of the stem on the other side of the pane and is secured to the stem, preferably through a press fit, thus sandwiching the glass pane securely between the shoulder and the washer. The valve plug may be part of the assembly thus secured to the glass pane, or it may be added after the plug body has been thus secured. Generally this placement of the valve will be accomplished before the panes are assembled into an insulating glass unit. The pane, with valve secured and preferably in its plugged position, is then employed in the assembly of an IG unit, the assembly commonly taking place in an atmosphere of e.g., argon to provide the unit with an argon filled between-pane space. 
     Once the insulating glass unit has been shipped to a desired location for installation the valve may be opened to allow the unit to “breath”, thus equalizing the pressure across the panes. Once this occurs, the threaded plug may be tightened to seal the insulating glass unit. If desired, the threaded plug may then be disabled to prevent tampering which would cause loss or contamination of the retained gas. Optionally, a cap may be placed over the shouldered portion of the valve body to further protect the valve from tampering by unauthorized persons. The cap may, optionally, be decorative in design. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front plan view of an embodiment of a pressure equalization valve administered to a pane of glass in accordance with the present invention. 
     FIG. 2 is a side plan view of an embodiment of a pressure equalization valve applied to a insulating glass unit in accordance with the present invention, the valve being shown in outline only to indicate its location with respect to the IG unit; 
     FIG. 3 is perspective, exploded view of an embodiment of a pressure equalization valve of the present invention; 
     FIG. 4 is a cross-sectional view of an embodiment of the pressure equalization valve of FIG. 3, in an open or unplugged configuration; 
     FIG. 5 is a cross-sectional view of an embodiment of the pressure equalization valve of FIG. 3 in a closed or plugged configuration; 
     FIG. 6 is a sectional view taken along line A—A of FIG. 2; 
     FIG. 7 is a plan view of an embodiment of the head of a threaded plug as used in accordance with the present invention; and 
     FIG. 8 is a plan view of an embodiment of a cap in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1-5 depict an embodiment of a pressure equalization valve  10  secured to a glass pane  11  within an optional frame  12  of an insulating glass unit  13 . Embodiments of a pressure equalization valve generally include a valve body  14 , a washer  16 , a valve plug  18 , and optionally, a cap  20 . As shown in FIG. 1, the valve  10  may be provided in a corner of an IG unit, just within the sight line, or may be placed beneath subsequently added trim or framing, such location being designated  10 A in FIG.  1 . 
     As depicted in FIGS. 3-5, the valve body  14  includes a generally cylindrical stem  22  having a shoulder  24  at one end. However, the shape of the stem may be of any shape which would provide similar functions. The shoulder  24  is adjoined with the stem  22  and includes an annular surface  23  which faces and confronts the surface of the glass pane  11  about the periphery of the aperture  15  extending through it. The stem and shoulder preferably are integrally formed by machining. The annular surface optionally includes an annular recess  26  which may receive sealant  28 . 
     In the embodiment depicted in FIGS. 3-5, the valve body includes an internal cavity  34  including a bore  32  extending longitudinally therethrough. Referring to FIGS. 4 and 5, the cavity  34  includes an internally threaded chamber  36  having a plug seat  38  at one end thereof and an inner chamber  35  at its other end. An optional enlarged bore entry  40  is also shown. Preferably, the internally threaded chamber  36  is smaller in diameter than the inner chamber  35  and the plug seat  38 . Bore entry  40  is normally larger in diameter than plug seat  38 . 
     The pressure equalization valve of the present invention also includes a washer assembly  16  comprising a washer and optional sealant for the purpose of securing the valve to a glass pane. The washer assembly includes a washer  41  bearing an aperture  42  that is sized to receive stem  22  therethrough. The washer assembly  16  may further include a flat face (not shown) or an annular recess  44  on one face, with an optional bevel  46  on its opposite face. The flat face or recess  44  may be adapted to accommodate the application of a sealant for adjoining and sealing the valve body  14  and glass pane  11  with the washer assembly  16 . 
     FIGS. 4 and 5 additionally illustrate an elongated valve plug  18  having a shaft  48  and head  50 . The shaft  48  includes a first threaded portion  56  adjacent the head  50 , an second threaded portion  52 , and an intermediate unthreaded portion  54 , the intermediate portion being longer than the axial length of the internally threaded chamber  36  and also of smaller diameter so as to establish a pathway for air or other gas to pass through the valve body when the plug is in the unplugged position shown in FIG.  4 . Head  50  includes a collar  58 , a sealing seat  60  onto which a sealing device  62  such as an O-ring may be received, and an exteriorly accessible tool-engaging element such as socket  64 . Socket  64  includes tool-engaging surfaces  65  adapted to receive any turning tool, such as an Allen wrench or a Phillips or flat head screwdriver. The tool engaging element may be of any appropriate type, such as a square or hexagonal head shaped to receive a wrench, etc. 
     Tool engaging surfaces  65  are preferably not frangible under high torque. However, in one embodiment, soft or otherwise readily deformed surface materials may be incorporated into the socket, these materials being readily distorted by application of high torque so as not to again be suitably engagable with the tools to rotate the valve plug, thus prevent reopening of the valve. The use of deformable surfaces in the socket  64  (as by incorporating a soft metal such as copper in the socket) would reduce undesired tampering with the pressure equalization valve  10  and thereby prevent unwanted opening of the valve. For example, the walls of an Allen wrench socket may be formed of a soft metal such that the application of substantial torque to the socket causes the surfaces to deform and become rounded. 
     When the valve plug has been threaded entirely into the valve body, as shown in FIG. 5, the head  50  of the plug is received in the bore entry  40  and the O-ring  62  seats in the plug seat  38  to provide a gas-tight seal. In this “plugged” position, the first threaded portion  56  of the valve plug is threadingly received in the threaded chamber  36 . When it is desired to open the valve, the valve plug is threaded out of the threaded chamber  36  into the position shown in FIG. 4, thereby opening a pathway for the flow of a gas through the valve body. However, inasmuch as the second threaded portion  52  of the valve plug is dimensioned to be threadingly received in the threaded chamber  36 , the valve plug cannot accidentally escape outwardly of the valve body. If it is desired to remove the valve plug entirely from the valve body, the inner threaded portion  52  may simply be unscrewed from the threaded chamber  36 . 
     The dimensions of the second threaded portion  52  and the threaded chamber  36  thus cooperate to enable the valve plug to be securably shiftable as it moves axially within the valve body, that is, in a manner preventing accidental escape of the valve plug from the valve body when the valve is in its unplugged position. 
     FIG. 6 depicts a top view of an embodiment of the pressure equalization valve  10 , wherein the head  50  is omitted to illustrate the relationship of the unthreaded stem  54  and the thread receiving chamber. Moreover, FIG. 6 is a top view of the lower half of an embodiment of the pressure equalization valve including the features below dividing line  55  of FIG.  4 . 
     Referring to FIGS. 5 and 8, optional cap  20  is sized so as to be received over shoulder  24  of valve  10 . Cap  20  may snap-fit over shoulder  24  of valve  10 , or may be held in place by a pressure-sensitive adhesive  68 , or by any other appropriate techniques. Cap  20  may optionally include a decorative design. The cap  20  may also be adapted to provide an additional sealing mechanism for the prevention of undesired leakage. The addition of sealing devices, such as an O-ring, may be included in the cap  20  if desired. 
     Pressure equalization valve  10  is preferably manufactured of a corrosion resistant metal such as brass or another suitable metal or alloy. However, it may be manufactured of any other material of appropriate strength, rigidity and corrosion resistance such as aluminum or an appropriate polymer. 
     If desired, the sealant  28  may be applied to the outer surfaces of the stem  22  and onto the facing surfaces of the shoulder and washer between which the glass pane is sandwiched. Sealant  28  desirably is a soft, formable polymer composition such as  40  polyisobutylene, and preferably is substantially impermeable to the selected gas filling. 
     In operation, referring to FIGS. 4 and 5, an appropriately sized hole is made in glass pane  12 . Valve body  14  is inserted into glass pane  12 , and as noted above, sealant may be applied to the valve body as illustrated. An annular ring of a formable sealant may be placed around the valve body and against the annular recess  26  so that as the shoulder  24  is pressed against the glass pane  11 , the sealant conforms to the confronting surfaces of the pane and the shoulder to form a gas-tight seal. Shoulder  24  is pressed snugly against the glass pane  12 . 
     The washer assembly  16  is applied over stem  22  against the other side of the glass pane with an appropriate pressing tool, e.g., a pliers with jaws appropriately shaped to contact the shoulder  28  of the valve body and the outer surface of the washer  41  until the washer is snugly positioned against glass pane  12 . Other pressing mechanisms, e.g., using pneumatic or hydraulic driven jaws to apply a predetermined appropriate force to the washer to secure it to the stem  22 , will be evident to the skilled artisan. If desired, the stem  22  and interior of the washer assembly  16  may be threaded in order to secure the washer assembly  16  to stem  22 , or, if desired, crimping may be employed to secure the washer to the stem or a separate threaded nut may be threaded onto a threaded end of the stem to urge the washer against glass surface. In the preferred embodiment, however, the washer assembly and the stem are so closely dimensioned as to permit the washer to be press-fitted over the stem  22 . Note that an annular ring of a formable sealant may be placed around the aperture of the washer and against the annular recess  44  so that as the washer is pressed against the confronting surface of the glass pane, the sealant conforms to the surfaces of the washer and glass, providing a gas-tight seal. 
     Another possible alternative is that pressure equalization valve  10  may also be located in the peripheral seal of an insulating glass unit if desired. The process as described above would be performed to place the pressure equalization valve  10  in the peripheral seal instead of the glass pane. It is further noted that the pressure equalization valve  10  may be concealed under a window frame or trim application as depicted in FIG.  1 . 
     Valves of the invention may be installed in glass sheets, preferably near the corners of the sheets (that is, preferably near the sight line of the panes after the IG unit has been appropriately framed), before the sheets are assembled into IG units. The valves desirably are installed in their closed or plugged positions, with a gas such as argon being included in the between-pane space during fabrication of the glass panes into IG units using known methods and apparatuses, one of which is shown in U.S. Pat. No. 4,909,874 (Rueckheim). Here, the glass panes and peripheral spacer are assembled while in an argon or other gas atmosphere. The completed IG unit commonly is shipped to another location at which it is provided with appropriate framing. 
     Once the manufacturing process is complete the insulating glass unit  13  may be shipped to the location of intended installation. At any time when it is desired to equalize the pressure differential across the glass panes, the valve plug may be unscrewed sufficiently to enable gas to flow through the valve until the pressure in the between-pane space is equal to ambient pressure. This step may be performed whenever needed. Although it may most often be used to relieve pressure differences encountered between the geographic location of assembly of the IG unit and the location where it is to be installed, it may be appropriate to equalize pressures at some other location. For example, an IG unit may be manufactured at a location near sea level, and then transported to an altitude of, say, 5000 feet (about 1500 meters) for ultimate installation in a building at an altitude of 8000 feet (about 2400 meters). Here, it may be convenient to equalize pressures at the 5000 feet location rather than the 8000 feet location. 
     The above description has referred primarily to enabling an IG unit to “breath” when the valve is opened in order to achieve pressure equalization, the valve “exhaling” argon or other gas when the pressure between the panes is greater than ambient pressure and “inhaling” air when the internal pressure is less than ambient pressure. It should be understood that the valve may, if desired, be connected to a source of a gas such as argon so that when the unit “inhales” as the valve is opened, it receives gas from that source. It may be desirable in some circumstances to purge the between-pane space by continuing to supply argon or other gas through the valve into the between pane space while concurrently permitting gas from within that space to escape outwardly through the valve. This may be accomplished, for example, by passing the gas under pressure through a flexible tube that extends at least partially through the valve. 
     While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations which fall within the spirit and broad scope of the invention.