OVEN WINDOW ENCAPSULATED PACKAGE

Abstract

This description provides a glass assembly comprising a plastic frame and two glass sheets in a spaced parallel arrangement, wherein at least one of the glass sheets is encapsulated within the plastic frame. The glass assembly is part of a door connected to an oven to allow selective access to the oven cavity. The encapsulated glass sheet may face either into the oven cavity or outward from the oven cavity, toward the external environment. Each glass sheet may also be encapsulated within a frame half, and the two frame halves may be connected together. The description also provides a method for making the glass assembly.

Description

OVEN WINDOW ENCAPSULATED PACKAGE FIELD OF INVENTION This description refers to insulated glass assemblies for use in oven doors and other applications such as medical cabinets or sterilization machines. More specifically, this description refers to oven door assemblies that have at least one sheet of glass encapsulated in plastic. BACKGROUND OF THE INVENTION Currently available window assemblies for commercial and residential oven doors are very expensive because they have many components that must be assembled to produce the combined window and door assembly. Insulated glass units (IGUs) used as oven window assemblies for oven doors often require numerous insulating seals, and in some cases, layers of insulating seals, to adequately insulate the inside of the oven cavity. Additionally, current oven window IGUs are typically made of glass and metal, and the metal frequently conducts heat from the oven cavity to other oven components and the outside environment. Furthermore, it is difficult to completely seal and insulate assemblies with many interconnected parts. With reference to Figure 1, a prior art oven door assembly is shown. As can be seen, there are many components that make up an oven door assembly. In particular, gasket 318 provides an insulating barrier between the glass sheets 338 and the door frame 340, and is often considered essential to prevent the leakage of hot air and moisture. Current assemblies can fail when the gasket dries out and cracks or breaks. BRIEF DESCRIPTION OF THE INVENTION The assemblies described herein alleviate many of the problems of current assemblies. These assemblies can utilize injection molding and can create a single, encapsulated part that holds the glass. The encapsulation process provides the correct separation between the glass panes to achieve the desired thermal performance and eliminates the need for the multiple insulating seals used in conventional assemblies. The encapsulated furnace window assemblies described herein can be fully complete, fold-out assemblies that only need to be mounted into a furnace door frame to provide the final combined furnace door and window assembly. Certain types of plastics (e.g., resins and polymers) provide better thermal insulation than metal, so heat transfer through the assemblies described herein can be minimized, if not eliminated, by selecting the plastic used as the encapsulating material. The complicated and time-consuming assembly of conventional assemblies can also be eliminated, as a one-piece molded frame can replace most, if not all, of the traditionally required parts. An encapsulation process, such as injection molding, allows the encapsulating material to be applied directly to the glass, thus making insulating seals (such as gaskets) between the frame supporting the glass sheet and the glass itself much less likely.However, since the two glass sheets may not be encapsulated, and since encapsulation may not provide a completely airtight seal with the glass, the gas between the glass sheets can breathe to some extent, entering and escaping from between them. This reduces the likelihood of explosive failures due to pressure changes caused by variations in the assembly's altitude or the heating of the air between the glass sheets. Put another way, the assemblies described herein greatly reduce or eliminate conductive heat transfer through the assembly.A small amount of convective heat transfer may occur because the assemblies are not necessarily completely airtight, but any gaps or imperfections represent an improvement over current assemblies and are acceptable due to the aforementioned benefits provided by the ability of the air or gas inside the assembly to equalize with the outside environment. The assemblies described herein also allow for modular variations where different types of glass and plastic can be used depending on the intended application. The present description achieves these objectives with an assembly comprising at least two glass sheets in a substantially parallel, spaced arrangement. The assembly can be attached to or connected to an oven door frame very quickly and easily. At least one of the sheets can be encapsulated with a resin or polymer material. The encapsulation material can be molded, for example, into an L-shape or a shape having two tabs (see, for example, Figure 3, which is discussed in more detail later, with the horizontal tab 2a and the vertical tab 2b forming the L-shape) such that at least one encapsulated sheet is encapsulated in one leg of the shape and the unencapsulated sheet can be attached to the remaining leg of the shape in such a way that the edge of the unencapsulated sheet is not visible from the outside of the oven door.Alternatively, each of two glass sheets can be encapsulated in resin or polymeric material, and the two separate encapsulation forms can be bonded together before being placed in an oven door. Thus, in one embodiment, the present description provides an assembly comprising a plastic frame, a first glass sheet, and a second glass sheet, wherein the first and second glass sheets are in a substantially parallel, spaced arrangement. The first glass sheet is encapsulated by the frame around a perimeter of the first glass sheet. The second glass sheet is not encapsulated by the frame. In another embodiment, the present description provides an assembly comprising: a plastic frame, wherein the plastic frame comprises a first frame half and a second frame half; a first glass sheet; and a second glass sheet, wherein the first glass sheet and the second glass sheet are in a substantially parallel, spaced arrangement. The first glass sheet is encapsulated within the first frame half. The first frame half and the second frame half are connected to each other. The second glass sheet may or may not be encapsulated by the second frame half. The present description also provides an oven comprising a glass assembly and an oven door, wherein the glass assembly is connected to the oven door and a housing. The oven door is connected to the housing, such that the oven door, the glass assembly, and the housing define an interior oven cavity. The first sheet of glass may be on one side of the glass assembly facing either the interior oven cavity or the exterior of the oven. The present description also provides methods for manufacturing glass assemblies comprising the steps of preparing a mold having a cavity that fits a frame shape, placing the first sheet of glass in the mold, melting and injecting a frame material into the mold and around the first sheet of glass, and cooling the frame material so that the first sheet of glass is encapsulated therein. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a part-separated view of an oven door assembly according to the prior art. Figure 2 is a top perspective view of an oven door including an assembly of the present description. Figure 3 is a detailed view of an assembly of the present description. Figure 4 is a second detailed view of an assembly of the present description, showing an area where an adhesive can be applied. Figure 5 is a detailed view showing how an assembly of the present description can be connected to an oven door. Figure 6 is a top perspective view of a second modality of the assembly described herein. Figure 7 is a detailed view of the assembly in Figure 6. Figure 8 is a top perspective view of a third modality of the assembly described herein. Figure 9 is a cross-sectional view of the assembly in Figure 8. iviA / a / ¿u¿ i / ui ju ji Figure 10 is a schematic drawing of a furnace including a glass assembly of the present description. DETAILED DESCRIPTION OF THE INVENTION With reference to the drawings, and in particular to Figures 2-5, Assembly 1 of the present description is shown. Assembly 1 includes a frame 2, an inner glass sheet 3, and an outer glass sheet 4. When Assembly 1 is used in an oven door, the inner glass sheet 3 faces into the oven cavity, and the outer glass sheet 4 faces the outside environment. The inner glass sheet 3 and the outer glass sheet 4 are in a substantially parallel, spaced arrangement, such that an interior space 5 is defined by the frame 2 and the two glass sheets 3 and 4. At least one of the inner glass sheet 3 and the outer glass sheet 4 is encapsulated within the frame 2. In the embodiment of Figures 2-5, the outer glass sheet 4 is encapsulated within the frame 2, and the inner glass sheet 3 is not encapsulated and is instead attached or connected to the frame 2.As will be described in more detail later, the inner glass sheet 3 can be encapsulated within the frame 2 instead of having the outer glass sheet 4 encapsulated within the frame 2, or each of the sheets 3 and 4 can be encapsulated within the frame 2. The assembly 1 can be connected to an oven door 10. Assembly 1 offers several significant advantages over currently available assemblies. The material used for frame 2 can be plastic, meaning it can be lighter than metal and does not experience the heat conduction prevalent in current metal assemblies. While encapsulation by injection molding can be a complex process, Assembly 1 can eliminate the need for multi-component oven doors. Many, if not all, current assemblies use components such as gaskets to prevent the leakage of air, heat, or moisture, but these components can fail. Currently available assemblies also have seals between the leaves and around the entire perimeter of the leaf edges. The assemblies described herein are not required to have seals between the leaves and do not require desiccants, spacers, or vapor seals. The encapsulation, along with the fact that in several configurations only one sheet is encapsulated, means that assembly 1 is not necessarily completely airtight. This can be an advantage because it allows the pressure in the internal space 5 to equalize with ambient pressures. When assembly 1 is used at high altitudes or at the high temperatures common in furnaces, a temporary pressure imbalance can occur across assembly 1, particularly between the internal space 5 and the ambient environment. Assembly 1 is designed to significantly reduce heat and moisture transfer, but enough air can migrate through assembly 1 to allow pressure imbalances to resolve. Current units may fail under these pressure imbalance conditions. Additionally, since frame 2 can be made from the same individual material, assembly 1 can eliminate concerns about thermal expansion mismatches that can cause sealing problems in current assemblies, for example, at joints between materials of different types. In this description, the glass sheets of the assemblies each have two faces, and each also has an edge that extends around the perimeter of each sheet. The edges have a dimension that corresponds to the thickness of the sheet. When each sheet is a rectangular solid, each glass sheet will have two faces and four edge segments. Two of the edge segments can be longer, i.e., lengths, and two can be shorter, i.e., widths. The perimeter of the glass sheet is the continuous path along the lengths and widths of the sheet. Thus, for assembly 1, as shown in Figures 2-5, each of the sheets 3 and 4 has edges 3a and 4a, respectively. They also have faces 3b, 3c, 4b, and 4c, respectively. Each of the sheets 3 and 4 also has length segments and width segments. Therefore, the perimeter of sheet 4 would be the sum of two segments of length 4d and two segments of width 4e.This description assumes that setup 1 can use sheets of shapes other than rectangles, such as squares (where the lengths and widths of the sheet are equal), triangles or other polygonal shapes, and circles, ovals, or ellipses. The perimeter of these different shapes is the sum of all the sides of a polygon, or the circumference of rounded shapes. Similar features can be found in setups 101 and 201, which are described below. By “encapsulation,” “encapsulant,” and “encapsulation,” the present description refers to a structure and a process where a material is molded, for example, by injection molding, around a part so that the material and the part become integral and cannot be separated without damaging one or both. In an encapsulation process, the material molded around the part is hot when applied and then contracts as it cools to grip or bond firmly to the part. With reference to the glass sheet 4 in Figure 4, the frame 2 contacts the sheet 4 on three surfaces—specifically, the edge 4a and faces 4b and 4c—to form a U-shaped encapsulation in cross-section. In the present description, the material for the frame 2 can encapsulate the edge 4a and a portion of faces 4b and / or 4c. When sheets 3 and / or 4 are encapsulated by frame 2, the frame material 2 runs along the entire perimeter, or all four sides, of sheet 3 or 4. This is known as “four-sided encapsulation.” If there is any break in the encapsulation around the perimeter sides of the sheet, assembly 1 may lose its effectiveness as a barrier against heat or water migration. As discussed earlier, encapsulation is not necessarily airtight, so air can travel from the interior space 5 to the ambient environment to equalize any pressure gradient between them. Encapsulation is distinct from a scenario where a sheet of glass is bonded to a plastic frame (with an adhesive or similar) that has already been formed separately. This description also includes a configuration where encapsulation occurs on only two sides of sheet 3 or 4, known as two-sided encapsulation. In this configuration, the unencapsulated sides may need to be sealed to prevent heat migration from the assembly. The same applies when sheets 3 and 4 are not solid rectangles; that is, the encapsulation may only be on one or two sides of the sheet or on part of its circumference. In encapsulation, the way in which frame 2 and glass sheets 3 and / or 4 are secured depends on the design of each, the type of frame material used, and the encapsulation process. During the encapsulation process, as discussed in more detail later, molten frame material is injected around the glass sheet. As the molten frame material cools, it contracts and tightly clamps the glass sheet. In encapsulation, there are usually no adhesives, chemicals, or any other substances used to hold the sheet and frame together. As described above, in the embodiments shown, the encapsulation is such that the frame material 2 contacts one edge and two faces, resulting in a U-shaped cross-section. In some applications, the frame material may only cover the edges of a sheet and a portion of only one face of the sheet. There would be no frame material on the other face of the sheet, so the frame material would be flush with the unencapsulated face. In these embodiments, as the plastic shrinks, it can separate from the glass since the encapsulation material does not touch both faces of the sheet. Primers, adhesive compounds, or bonding agents can be used to bond the frame material and the sheet together in two-sided encapsulation. It may also be possible to use a frame material that does not shrink as much and is thus less likely to peel off.In another configuration, the framing material is applied only along the edge of the sheet and not on either side. Here, the framing material is flush with both sides of the sheet. This configuration may also require the use of primers, adhesives, or bonding agents. Referring specifically to Figures 3 and 4, the frame 2 has a horizontal flange 2a and a vertical flange 2b. On the vertical flange 2b, for example, on a surface of the vertical flange 2b that is coplanar with face 3b of the sheet 3, there may be a sealing area 2c. An adhesive or other sealant can be applied to this area 2c so that the inner glass sheet 3 can be bonded or sealed to the frame 2 or the oven door 10. The adhesive or seal shown and described in Figures 3 and 4 next to the unencapsulated sheet 3 is located in a different place than conventional seals, which are found on the perimeter edges. Conventional seals on the outside are usually around the perimeter parallel to or adjacent to the edges of the sheet. Again, the present assemblies provide a much more efficient design. The seal formed between the inner glass sheet 3 and the frame 2 or oven door 10 in area 2c can be airtight to prevent hot air from escaping the oven cavity. As shown, since the inner glass sheet 3 is sealed in area 2c, the sealant is not visible from the outside of assembly 1. Additionally, either of the tabs 2a and 2b can be used as mounting locations for other components, such as lights (not shown). As shown in Figure 5, assembly 1 can be attached to the oven door 10. Assembly 1 may have a mounting tab 6 that is connected to, or is an integral part of, the frame 2. The mounting tab 6 may have a hole 7 through it. The oven door 10 may have a surface 11, with a bolt 12 projecting from it. Assembly 1 can be attached to the door 10 by passing the bolt 12 through the hole 7. This description contemplates other ways of attaching assembly 1 to the oven door 10, such as with other fasteners or adhesives. The oven door 10 with assembly 1 attached to it is connected to the rest of the oven (see Figure 10, discussed later) to insulate the interior cavity of the oven. With reference to Figures 6 and 7, a second embodiment of assembly 101 of the present description is shown. Assembly 101 has the frame 102 (with the vertical tab 102a and the horizontal tab 102b), the inner glass pane 103, and the outer glass pane 104. Assembly 101 is similar to assembly 1, except that in assembly 101, the inner glass pane 103 is encapsulated by the frame 102, and the outer glass pane 104 is not encapsulated. The outer glass pane 104 is connected to the frame 102 by means of a plurality of snap-fit ​​mechanisms or cantilevers 102c located on the horizontal flange 102b around the perimeter of the outer glass pane 104. To connect the outer glass pane 104 to the frame 102, a user simply adjusts the pane 104 using the snap-fit ​​mechanisms 102c. In this way, an interior space 105 is defined by the frame 102, the inner glass pane 103, and the outer glass pane 104.An adhesive (not shown) may be used. Encapsulation in assembly 101 can provide similar benefits to assembly 1, specifically, preventing the migration of heat and moisture from inside a furnace cavity to the outside ambient environment. Since the outer glass sheet 104 is press-fit, it may not provide as much heat, moisture, or air migration as the outer sheet 4 in assembly 1, but it has the advantage of being potentially easier to assemble or disassemble. With reference to Figures 8 and 9, a third embodiment of the assembly described herein is shown by reference number 201. Assembly 201 has a frame 202 comprising two separate components, specifically, a first frame 202a and a second frame 202b. Assembly 201 is shown without an inner and an outer glass pane, but at least one pane of each pane would be encapsulated within the first frame 202a or second frame 202b in a manner similar to the preceding embodiments. The first frame 202a and the second frame 202b are connected or bonded together to form a single combined frame. The first frame 202a and the second frame 202b can be connected together by glue, adhesive, fasteners, interlocks, snap fasteners, heat stakes, vibration welding, and combinations thereof, as non-limiting examples. With reference to Figure 10, an oven 20 of the present description is shown. The oven 20 has the oven door 10 and housing 15. The housing 15 is the outer casing of the oven 20. For example, in an oven that is a cube or rectangular solid, the housing 15 would include five of the six sides of the solid, and part or all of the front face. The door 10 would be on or comprise the entire front face. The door 10 and the housing 15 define an internal cavity 25 where products, for example, food products, are heated. As described above, assemblies 1, 101, and 201 of the present description are connected to the oven door 10, which in turn is connected to the housing 15. To perform any of the assemblies described herein, a person skilled in the art may use any known encapsulation process. For example, a steel mold is fabricated in the desired shape. The glass sheet to be encapsulated is placed in the mold. The frame material (2, 102, 202) is injected into the mold in molten form. Since the other glass sheet in the assembly is not present in the mold, a form or barrier may be placed in the mold to ensure that the molten frame material takes the desired shape. The material is cooled, and the form or barrier is removed. The second glass sheet is then bonded to the completed injection-molded frame, as in assembly 1, or fitted, as in assembly 101. For assembly 201, the encapsulation process is performed for each sheet, and then, as described later, the two separate frames are connected together. The frame material described herein must be capable of withstanding very high temperatures, such as those used in residential ovens operating up to 1,000 degrees Fahrenheit (537.78 degrees Celsius), pyrolytic ovens operating up to 900 degrees Fahrenheit (482.22 degrees Celsius), roasting ovens operating up to 600 degrees Fahrenheit (315.55 degrees Celsius), and steam ovens operating up to 500 degrees Fahrenheit (260 degrees Celsius). At the same time, the material must be workable enough to form the frame through encapsulation. Important factors in material selection include flow, elasticity, shrinkage, impact resistance, and temperature resistance. The material must be durable enough to resist warping, loss of rigidity, or melting at temperatures up to at least 500 degrees Fahrenheit (260 degrees Celsius).In other words, the frames of the assemblies described herein must maintain their structural integrity and not degrade after cooling the material and encapsulating the glass sheets as described above, at temperatures of at least 500 degrees Fahrenheit (260 degrees Celsius). Suitable materials include, but are not limited to, nylon or polypropylene polymers. The glass used in this description can be any glass suitable for use in furnaces, such as soda-lime glass, coated soda-lime glass, ceramic glass, or Schott Borofloat® glass. The glass can be coated and / or functionalized on one or both sides. For example, it can be heated glass, illuminated glass, or electrochromic glass (switchable glass), or it can have one or more layers of transparent conductive oxide (TCO), a low-emissivity coating, a hydrophobic coating, and / or an anti-fog coating. All of this is possible provided the encapsulation on the sheets is not broken. Although the present description has been given with reference to one or more exemplary embodiments, those skilled in the art will understand that various changes can be made and equivalents substituted for the elements of these embodiments without departing from the scope of the present description. Furthermore, many modifications can be made to adapt a particular situation or material to the teachings of the description without departing from its scope. Therefore, it is intended that the present description not be limited to the particular embodiments described as the best contemplated embodiment, but rather that the description include all embodiments that fall within the scope of the appended claims.

Claims

1. An assembly comprising: a plastic frame; a first sheet of glass; and a second sheet of glass, wherein the first sheet of glass and the second sheet of glass are in a substantially parallel spaced arrangement, wherein the first sheet of glass is encapsulated by the frame; wherein the second sheet of glass is not encapsulated by the frame.

2. The assembly of claim 1, wherein the first sheet of glass has a perimeter, and wherein the first sheet of glass is encapsulated by the frame around the perimeter.

3. The assembly of claim 2, wherein the first sheet of glass is a rectangular solid having four sides that form the perimeter.

4. The assembly of claim 1, wherein the frame comprises a vertical leg and a horizontal leg.

5. The assembly of claim 4, wherein the first sheet of glass is encapsulated by the horizontal leg and wherein the second sheet of glass is not encapsulated.

6. The assembly of claim 4, wherein the first sheet of glass is encapsulated by the vertical leg and wherein the second sheet of glass is not encapsulated.

7. The assembly of claim 2, wherein the second glass sheet is connected to the vertical leg.

8. The assembly of claim 1, wherein the second sheet of glass is connected to the frame in a hermetic manner.

9. The assembly of claim 7, wherein the second sheet of glass is connected to the vertical leg with an adhesive.

10. The assembly of claim 7, wherein the second glass sheet is connected to the vertical leg with a plurality of pressure mechanisms.

11. The assembly of claim 1, wherein the frame is made of a material that does not degrade at 500 degrees Fahrenheit (260 degrees Celsius).

12. The assembly of claim 1, wherein there is no spacer between the first sheet of glass and the second sheet of glass.

13. The assembly of claim 1, further comprising a transparent conductive oxide (TCO) layer, a low emissivity layer, a hydrophobic layer and / or an anti-fog layer provided on one or more of the first glass sheet and the second glass sheet.

14. An assembly comprising: a plastic frame, wherein the plastic frame comprises a first frame half and a second frame half that are separately formed components; a first glass sheet; and a second glass sheet, wherein the first glass sheet and the second glass sheet are in a substantially parallel spaced arrangement, wherein the first glass sheet is encapsulated by the first frame half, and wherein the first frame half and the second frame half are connected to each other.

15. The assembly of claim 14, wherein the second sheet of glass is encapsulated by the second half of the frame.

16. An oven comprising: the glass assembly of claim 1; an oven door, wherein the glass assembly is connected to the oven door; and a housing, wherein the oven door is connected to the housing such that the oven door, the glass assembly, and the housing define an inner oven cavity, wherein the first sheet of glass is on a side of the glass assembly facing into the inner oven cavity.

17. An oven comprising: the glass assembly of claim 1; an oven door, wherein the glass assembly is connected to the oven door; and a housing, wherein the oven door is connected to the housing such that the oven door, the glass assembly, and the housing define an inner oven cavity, wherein the first sheet of glass is on a side of the glass assembly that faces away from the inner oven cavity.

18. A method for manufacturing the glass assembly of claim 1, comprising the steps of: preparing a mold having a cavity that fits a frame shape; placing the first sheet of glass in the mold; injecting the frame material into the cavity and around the first sheet of glass; and cooling the frame material so that the first sheet of glass is encapsulated by the frame material.

19. The method of claim 18, further comprising, after the step of placing the glass sheet, the step of: placing a barrier in the mold on top of the first glass sheet so that the barrier prevents migration of the molten frame material in the first glass frame beyond a desired point.

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