BACKGROUND

[0001] The present invention relates to an insulating glazing element and, more particularly, to a low-heat-loss edge profile for insulating glazing elements such as window lites.

[0002] Many existing insulating glazing elements (e.g., dual-pane, triple-pane insulating glass (“IG”) assemblies, or vacuum insulating glass (“VIG”) units) include two or more glass panes that are separated from each other by a space. An example of existing glazing element is illustrated in FIG. 1. As illustrated, the glazing element has a first glass pane 1 and a second glass pane 2 that is spaced or separated from the first glass pane 1 to form a space or gap. A gas-tight edge seal element 3 (e.g., a bridge element) extends along the perimeter of the space or gap between the glass panes to form an enclosed volume of controlled gas composition. As shown, and as is common in existing assemblies, the glass panes are of substantially uniform thickness. These designs can offer uniformly-low thermal conductance from the exterior surface of one pane to the exterior surface of the other pane over the interior region of the assembly (i.e. “center-of-glass region”) due to the enclosed volume, but existing edge seals form an undesirable thermal bridge between the edges of the glass panes such that the local thermal conductance rises near the edges of the assembly (“edge- of-glass region”).

[0003] The rise in thermal conductance at the edge-of-glass region in existing assemblies results in heat loss (sometimes referred to as “parasitic” heat loss), which raises the average heat conductance of the entire assembly. The overall conductivity of the panel is determined by the ratio of the surface area of the glass multiplied by the conductance of the center-of-glass region, and the surface area of the glass multiplied by the conductance of the edge-of-glass region. The frame in which the insulating glazing unit is mounted often has a higher conductance that the average conductance of the glazing unit, and adds to the parasitic heat loss for a window. The smaller the window, the smaller the area ratio of center-of-glass region to edge-of-glass region and frame. Thus, smaller windows tend to lose more heat.

[0004] One strategy to reduce the impact of parasitic heat loss is to use a frame with lower conductance. Another strategy is to increase the “bite” of the frame, that is, the extent to which the frame overlaps a portion of the edge-of-glass region of the glazing. This overlap reduces the size of the viewing area through the glazing that is not obstructed by the frame bite (“daylight opening”). Increasing the bite increases the length of the glass heat path from the edge of the daylight opening on one pane to the edge of the daylight opening on the opposite pane by way of the edge seal or thermal bridge. A longer heat path (typically U-shaped in cross-section) results in higher thermal resistance and lower overall conductance (thermal resistance is the inverse of thermal conductance). However, increasing the bite has the disadvantage of reducing the daylight opening, requiring expensive redesign of the frame, or both.

SUMMARY

[0005] The present invention is based on the principle that thermal conductance along the U- shaped heat path through the edge seal can be minimized by reducing the thickness of the glass panes at or inboard of the edge seal relative to the center-of-glass region. In one construction, the thickness of one or both glass panes may be reduced by diamond grinding. The finish quality of such diamond machining is aesthetically indistinguishable from the unmachined lateral surfaces of float glass. For example, grinding the pane(s) adjacent and/or at the edge to half the thickness of the remainder of the pane(s) would double the thermal resistance (and would increase even more for relatively small lites).

[0006] In one aspect, the invention is directed to the use of glass panes that are ground on one side only to create a uniform thickness over an area extending inward from the outer pane edges about 1 inch. The greater this width, the longer the high-resistance glass heat path created.

[0007] In another aspect, the invention is directed to a gas-tight enclosure including a first wall element, a second wall element, and a spacer system positioned between the first wall element and the second wall element and defining an interior space between the first and second wall elements. The first wall element has a first edge and a first center-of-glass region, and the second wall element has a second edge and a second center-of-glass region. The enclosure also includes a bridge element extending between adjacent edges of the first and second wall elements to isolate the interior space from a surrounding environment. At a location along the first wall element and inboard of the bridge element, the first wall element has a cross-sectional profile with a reduced thickness relative to a thickness of the first center-of-glass region. [0008] In one aspect, the invention is directed to a method for manufacturing an enclosure. The method includes assembling first and second wall elements together and separating the two wall elements from each other to form a space, and extending a bridge element between adjacent edges of the first and second wall elements and forming a gas-tight enclosure. The first wall element has an edge and a center-of-glass region, and at least a portion of the edge has a first thickness, and the center of glass region has a second thickness that is larger than the first thickness.

[0009] In one aspect, the invention is directed to an insulated glazing unit including a first flat panel element, a second flat panel element, and a plurality of spacers disposed between the first flat panel element and the second flat panel element to space the first flat panel element from the second flat panel element. The first flat panel element has a first edge with a first edge profile in cross-section and a first center-of-glass region that has a first center-of-glass region profile in cross-section. The second flat panel element has a second edge with a second edge profile in cross- section and a second center-of-glass region having a second center-of-glass region profile in cross- section. At least a portion of the first edge profile has a thickness that is smaller than a thickness of the first center-of-glass-region profile.

[0010] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0100] Fig. l is a cross-section view of pane edge profiles for a conventional glazing element including same-sized panes.

[0101] FIG. 2 is a cross-section view of an assembly illustrating a frame and a sash that support an exemplary glazing unit supported by the frame and sash.

[0102] Fig. 3A is a plan view of a corner portion of a glazing unit with a boundary between the region of uniform thickness and a region of reduced thickness following a radius at the corner.

[0103] Fig. 3B is a plan view of a corner portion of another glazing unit with the boundary between the region of uniform thickness and the region of reduced thickness that forms a 90-degree angle at the corner. [0104] FIG. 4 is a cross-section view of a portion of a glazing unit including first and second glazing units or panes or flat panel elements having an exemplary reduced edge profile.

[0105] FIG. 5 is a cross-section view of a portion of a glazing unit including first and second glazing units or panes or flat panel elements having another exemplary reduced edge profile with a beveled edge.

[0106] Fig. 6 is a cross-section view of a portion of a glazing unit including first and second glazing units or panes or flat panel elements having grooved edge profiles.

[0107] Fig. 7A-7D are cross-section views of portions of glazing elements including first and second glazing units or panes or flat panel elements having other exemplary edge profiles.

[0108] Fig. 8 is a bar chart illustrating a comparison of overall window thermal resistance for a conventional glazing unit consistent with FIG. 1, and a glazing unit having glazing elements or panes or flat panel elements with edge profiles consistent with FIG. 4 when mounted in an insulated metal frame of daylight opening of only 1.94 sq. ft.

[0011] It should be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. For example, it should be understood that the invention can encompass some features described below without certain features that may be described in intervening sentences or paragraphs (e.g., describing feature A, then feature B, and then feature C does not require that features A, B, and C be claimed together or in combination). Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

DETAILED DESCRIPTION

[0012] As used herein, the terms “insulated glazing unit,” “glass panel assembly,” “lite,” and “glazing unit” are synonymous and denote a window glazing assembly formed from one or more glass members or glass elements (referred to as glass panes for purposes of description) that are at least partially transparent to electromagnetic radiation, that are substantially parallel along their planar faces, and that are substantially congruent shapes with surrounding edges sealed to form an interior space between the glass panes. The interior space can be at least partially filled with a gas that is less conductive than air, or evacuated (e.g., by drawing a vacuum). These terms also encompass flat panel assemblies that have at least one element including glass and another element that can include glass, ceramic, aluminum, stainless steel, or other material. The edge seal element may include such materials as metal, glass or organic sealants, and may be either flexible or non- compliant in nature.

[0013] The term “pane” refers to a glass element intended for use as a wall element in a flat sealed enclosure assembly.

[0014] The terms “flexible” and “compliant” refer to a structure having a resilient nature, and the ability to accommodate movement.

[0015] The term “non-compliant” refers to a structure having a rigid or brittle nature, in contrast with “flexible” or “compliant”.

[0016] The term “inboard,” with respect to a seal or bridge element location, refers to a location on the side of the seal that is closest to the centroid of a glass pane.

[0017] The term “center-of-glass” with respect to a region on a lite or glass pane, refers to a location on the side of the seal that is closest to the centroid of a glass pane.

[0018] The term “low-e” refers to a low-emissivity metal-containing coating on a glass pane to increase the resistance of said pane to the passing of light radiation that is substantially outside the visible range of frequency.

[0019] The term “spacerettes” refers to tiny, barely visible structural members that are typically deployed in a uniform array pattern to maintains the gap between panes in a VIG after evacuation.

[0020] While the invention described in detail below and illustrated in the Figures encompasses a glazing unit with two glazing elements, it should be appreciated that the invention also applies and encompasses glazing units with more than two glazing units as well. [0021] FIG. 2 illustrates an exemplary glazing unit assembly 10 that can be installed into an opening 15 (e.g., rough opening). As shown, the assembly 10 includes a nested frame 20 that engages the exterior extents of the opening 15 and that has a frame 25 and a sash 30. The sash 30 supports a glazing unit 35 and defines an edge-of-glass region 40 (as shown in FIG. 2, the edge- of-glass region may be equivalent to the ‘bite’ shown in FIG. 2, although this may not always be the case). The glazing unit 35 has first and second glazing elements 45a, 45b that extend between opposite sashes 30 (only one sash is shown in FIG. 2). As illustrated in FIG. 2, the first and second glazing elements 45a, 45b are defined by different portions of the same glazing element 45, and can be formed by bending, crimping, or folding one portion (e.g., portion 45a) relative to the remaining portion (e.g., portion 45b). The opposite ends of the glazing elements 45a, 45b may include a bridge element (not shown) to seal the gap between the elements 45a, 45b. Other non limiting examples of glazing units embodying the invention are described in detail below with regard to FIGS. 4-7D.

[0022] With continued reference to FIG. 2, the glazing element portions 45a, 45b have an edge 47 that abuts or is positioned adjacent an interior of the sash 30. In some constructions, the edge 47 may be defined by different glazing elements 45a, 45b. The edge portion of the glazing elements 45a, 45b adjacent and inboard the sash 35 (e.g., inboard of a bridge element configured to seal the gap between the glazing elements 45a, 45b in constructions with a bridge element) is defined as an inboard edge-of glass region 50, and the portion of the glazing element portions 45a, 45b between opposite inboard edge-of glass regions 50 defines a center-of-glass region 50. The glazing element portions 45a, 45b shown in FIG. 2 have a non-uniform thickness from the edge 47, and through the regions 40, 50 toward the center-of-glass region 55. That is, the edge-of-glass region 40 and the inboard edge-of-glass region 50 have a thickness that generally increases from the edge 47 toward the center-of-glass region.

[0023] In general, the invention described and illustrated herein embodies a region of uniform glass thickness at or adjacent the center-of-glass region 55 and an area of reduced glass thickness along or adjacent the edge of the glazing element(s) 45 (the edge-of-glass region 40, or both regions 40, 50). FIGS. 3 A and 3B show portions of exemplary glazing units 35a, 35b at one corner. In FIG. 3 A, a boundary 60a between the region of uniform glass thickness (center-of-glass region 55) and the region of reduced glass thickness (one or both of regions 40, 50) follows a radius at the corner. In FIG. 3B, the boundary between the region of uniform glass thickness and the region of reduced glass thickness forms a 90-degree angle at the corner. It will be appreciated that the glazing unit can include other types of boundaries between the region of uniform glass thickness and the region of reduced glass thickness.

[0109] FIGS. 4-7D illustrate exemplary glazing units 35 that have different reduced-thickness profiles that reduce heat loss along the edge due to the more-resistant heat flow path on either side of a bridge element 65. In these constructions of the glazing unit 35, the glazing elements 45a, 45b are separated by spacers, and the bridge element 65 (e.g., a seal or other element in combination with seal material, including but not limited to foil) extends between the edges of the glazing elements 45a, 45b to define an insulated gap between the glazing elements 45a, 45b. It will be appreciated that the bridge element 65 can take many different forms, including the type that facilitates a vacuum-insulated gap.

[0110] FIG. 4 shows an exemplary glazing unit 35 with glazing elements 45a, 45b that are defined by funnel edge profiles. Each glazing element 45a, 45b has a substantially uniform first thickness in the edge-of-glass region 40a, 40b (e.g., inboard of the bridge element 65), and a taper that extends from or bridges the edge-of-glass region 40a, 40b to the center-of-glass region 55a, 55b, which has a second thickness. The first thickness is smaller than the second thickness. Although not explicitly labeled, the reduced thickness can extend into the inboard edge-of-glass region 50a, 50b, or the entirety of the regions 40a, 50a, 40b, 50b. As shown, the reduced thickness profile extends from the edges 47 of the glazing elements 45a, 45b to the center-of-glass regions 55a, 55b.

[0111] FIG. 5 illustrates an exemplary glazing unit 35 with glazing elements 45a, 45b that are defined by beveled edge profiles. Each glazing element 45a, 45b has a substantially flat bevel on the exterior side that tapers continuously larger toward the center-of glass region 55a, 55b such that the edges of the glazing elements 45a, 45b (e.g., in the edge-of-glass region 40a, 40b, or inboard of the bridge element 65, or both) have the smallest thickness and the center-of glass region 55a, 55b have the largest thickness. As shown, the reduced thickness profile extends from the edges 47 of the glazing elements 45a, 45b to the center-of-glass regions 55a, 55b. [0112] FIG. 6 illustrates an exemplary glazing unit 35 with glazing elements 45a, 45b that are defined by grooved edge profiles. Each glazing element 45a, 45b has a substantially flat edge-of- glass region 40a, 40b with a first thickness, an inboard edge-of-glass region 50a, 50b (e.g., beginning inboard of the bridge element 65) with a second thickness, and a center-of-glass region 55a, 55b that has a third thickness. The first and third thicknesses may be equal of different, and the second thickness is smaller than the first and third thicknesses to define a reduced thickness profile in the inboard edge-of-glass regions 50a, 50b. Although not explicitly shown, the reduced thickness can extend into a portion of the edge-of-glass region 40a, 40b (e.g., outboard of an inward extent of the bridge element 65). Also, the length of the reduced thickness region or groove in this example (measured outboard to inboard along the glazing element(s) 45a, 45b) can vary depending on the application of the glazing unit 35.

[0113] Fig. 7A-7D are cross-sectional views of various other glazing units 35 that have different edge profiles with reduced heat loss along the edge due to the more-resistant heat flow path on either side of the bridge element 65. FIG. 7A illustrates glazing elements 45a, 45b with edge profiles that flat on the exterior side and that define a ramp or reduced taper from the center- of-glass regions 55a, 55b toward the edge-of-glass-regions 40a, 40b such that the thickness of the regions 40a, 40b are smaller than the regions 55a, 55b. As shown, the center-of-glass regions 55a, 55b are closer to each other than the edge-of-glass regions 40a, 40b. Stated another way, FIG. 7 A illustrates glazing elements 45a, 45b that are inverted relative to what is shown in FIG. 4, which creates a larger gap between the elements 45a, 45b.

[0114] FIG. 7B illustrates glazing elements 45a, 45b with dual funnel edge profiles that are similar to what is shown in FIG. 7A, except the exterior side and the interior side have tapers from the center-of-glass regions 55a, 55b toward the edge-of-glass regions 40a, 40b such that the thickness of the regions 40a, 40b are smaller than the regions 55a, 55b.

[0115] FIG. 7C illustrates an exemplary glazing unit 35 a first glazing element 45a that is the same as the glazing element 45a described with regard to FIG. 4 with a smaller thickness in the edge-of-glass region 40a (and in some constructions, part or all of the inboard edge-of-glass region 50a), and a second glazing element 45b that is substantially uniform in thickness that is larger than the reduced thickness in the region 40a. [0116] FIG. 7D illustrates an exemplary glazing unit 35 that is similar to FIG. 7C, except the first glazing element 45a is flipped so that there is a larger gap between the glazing elements 45a, 45b in the edge-of-glass region 40a (and in some constructions, in all or part of the inboard region 50a). The second glazing element 45b is substantially uniform in thickness that is larger than the reduced thickness in the region 40a.

[0117] FIG. 4-7D illustrate different combinations of glazing elements 45a, 45b that are defined by different profiles. It will be appreciated that these Figures illustrate only a sample of the different combinations of glazing elements 45a, 45b that embody the invention described and illustrated in the Figures, and that additional or different combinations are possible and within the scope of the invention.

[0118] Fig. 8 illustrates a bar chart that compares the overall window thermal resistance (which is the inverse of is thermal conductance) for a glazing unit with subtantially uniform thickness (consistent with what is illustrated in FIG. 1), and a glazing unit 35 that has a reducededge profile consistent with what is illustrated in FIG. 4 when each unit is mounted in an insulated metal frame of daylight opening of only 1.94 sq. ft.

EXAMPLES

[0024] Example 1: Four panes of common soda lime window glass, each 3.2 mm thick and two having a triple silver low E coating, are cut to 14 inches by 20 inches. The edges of one clear pane and one low-e coated pane are ground to the profile shown in Figure 4. The other two are left unground, so that the edge thickness of each pane remains the same as the remainder of that pane (consistent with what is shown in FIG. 1). The unground panes are populated with an array of spacerettes, assembled one atop the other with spacerettes and low-e coating in the gap, edge- sealed with solder glass, degassed, evacuated, and sealed off to form a VIG of small size having a center-of-glass thermal resistance of R15. The two VIGs are mounted in side-by-side openings in a highly-conductive metal factory sash frame. The metal frames are insulated to reduce frame heat loss. The overall heat resistance - the VIG and the insulated frame - are measured and compared. The results are summarized in Figure 8.

[0025] Figure 8 illustrates that the VIG with the conventional uniform edge profile has a thermal resistance of R4.87, while the VIG with the reduced thickness edge profile has a thermal resistance of R7.81, almost 60% better. The latter is remarkable performance for a lite of such small size. The only difference between the two VIGs is the relative thicknesses of the edge profiles. In the sample with the reduced edge profiles, the reduced thickness extends into the inboard edge-of-glass region (i.e. inboard of the bridge element or seal). For both VIGs, the conductivity of the edge seal or bridge element, which acts as thermal bridge, is identical. The VIG with the reduced edge profiles restrict the amount of heat that can reach the thermal bridge.

[0026] Example 2: Two panes of common soda lime window glass, each 3.2 mm thick, and two surfaces having a triple silver low E coating, are cut to 24 inches by 42 inches, or about 7 sq. ft in area, which is the median size for the residential market. The edges are ground to the profile shown in Figure 4. The panes are populated with an array of spacerettes, assembled one atop the other with spacerettes and low-e coating in the gap, edge-sealed with solder glass, degassed, evacuated, and sealed off to form a VIG having a center-of-glass thermal resistance of R15. This medium-sized VIG is mounted in a highly-conductive metal factory sash frame, identical in cross- section to that in Example 1. The metal frames are insulated to reduce frame heat loss. The overall heat resistance - the VIG and the insulated frame - is determined to be R9.9. The only difference is a larger ratio of center-of-glass area to edge-of-glass and the frame area. The latter is remarkable performance for a lite of such moderate size.

[0027] It is understood that the invention may embody other specific forms, or incorporate combinations of the embodiments described herein, without departing from the spirit or characteristics the invention. While specific embodiments have been illustrated and described, other modifications may be made without significantly departing from the spirit of the invention.

[0028] Various features of the invention are set forth in the following claims.