Patent Publication Number: US-2023137842-A1

Title: Vacuum insulation structures with multiple insulators

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a Divisional of U.S. patent application Ser. No. 17/037,855, entitled, “VACUUM INSULATION STRUCTURES WITH MULTIPLE INSULATORS,” filed Sep. 30, 2020, which is a Continuation of U.S. patent application Ser. No. 15/776,276, entitled “VACUUM INSULATION STRUCTURES WITH MULTIPLE INSULATORS,” filed May 15, 2018, now U.S. Pat. No. 10,808,987, which is a national stage entry of PCT/US2016/063966, filed on Nov. 29, 2016, which claims the benefit under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 62/265,055 filed Dec. 9, 2015. The entire disclosures of each are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     The efficiency of a refrigerator may, at least in part, rely on the refrigerator&#39;s ability to keep items within the refrigerator cool and prevent heat from entering the refrigerator. Accordingly, new methods and materials of insulating a refrigerator are sought. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     According to one aspect of the present disclosure, a method for manufacturing a vacuum insulated structure includes positioning an inner liner within an external wrapper and defining a gap between the inner liner and the external wrapper, drawing a vacuum to seal the gap, and injecting a first insulator into the gap. The method further includes positioning a filter proximate to the first insulator within the gap and injecting a second insulator into the gap proximate to the filter. 
     According to another aspect of the present disclosure, a method for manufacturing a cabinet for a refrigerator includes positioning a liner within a wrapper to define a gap and dispensing a first insulator within the gap through a back aperture of the wrapper. The method further includes positioning a filter on the first insulator and dispensing a second insulator within the gap through the back aperture and proximate to the filter. 
     These and other features, advantages, and objects of the present disclosure will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of the disclosure, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the disclosure, there are shown in the drawings, certain embodiment(s). It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities shown. Drawings are not necessarily to scale. Certain features of the disclosure may be exaggerated in scale or shown in schematic form in the interest of clarity and conciseness. 
         FIG.  1 A  is a top perspective view of a refrigerator cabinet, according to one embodiment; 
         FIG.  1 B  is an exploded top perspective view of the refrigerator cabinet of  FIG.  1 A , according to one embodiment; 
         FIG.  1 C  is a cross-sectional view taken at line IC- 1 C of  FIG.  1 A , according to one embodiment; 
         FIG.  2 A  is a cross-sectional view taken at line II- 11  of  FIG.  1 A , according to one embodiment; 
         FIG.  2 B  is a graph depicting the thermal conductivity of various insulator materials as a function of gas pressure; 
         FIG.  3 A  is a schematic depiction of a refrigerator cabinet insulator filling system, according to one embodiment; 
         FIG.  3 B  is a flow chart of a refrigerator cabinet insulator filling method, according to one embodiment; 
         FIG.  4 A  is a schematic depiction of a refrigerator cabinet insulator filling system, according to one embodiment; and 
         FIG.  4 B  is a flow chart of a refrigerator cabinet insulator filling method, according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     As required, detailed embodiments of the present disclosure are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to a detailed design and some schematics may be exaggerated or minimized to show function overview. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present disclosure. 
     As used herein, the term “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. 
     It is to be understood that the present disclosure is not limited to the particular embodiments described below, as variations of the particular embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments, and is not intended to be limiting. Instead, the scope of the present disclosure will be established by the appended claims. 
     For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the disclosure as oriented in  FIG.  1 A , unless stated otherwise. However, it is to be understood that the disclosure may assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     Referring to  FIGS.  1 A- 4 B , a refrigerator  10  includes a cabinet  14  having an inner liner  18  and an external wrapper  22 . The inner liner  18  is positioned within the external wrapper  22  such that a gap  26  is defined between the external wrapper  22  and internal liner  18 . A first insulator  30  is positioned within the gap  26  and a second insulator  34  is positioned within the gap  26 . A pressure within the gap  26  may be below about 1000 Pa. 
     Referring now to  FIGS.  1 A and  1 B , the refrigerator  10  includes the cabinet  14 . The refrigerator  10  may take a variety of configurations including French door, side-by-side, top freezer, bottom freezer, counter depth, compact, built-in, and other types of refrigerators. The cabinet  14  includes the inner liner  18 , the external wrapper  22  and may optionally include a shell  42 . In the depicted embodiment, the inner liner  18  has a generally rectangular box shape, but may take a variety of shapes including a cube, prism, parallelepiped, etc. and combinations thereof. The inner liner  18  may have a liner flange  46  disposed around the inner liner  18  and connected to a plurality of liner walls  50  which define the inner liner  18 . The inner liner  18  may be formed from a polymeric material having high barrier properties (e.g., low gas permeation), metals and combinations thereof. The inner liner  18  may be formed via thermoforming, injection molding, bending and/or forming. The liner walls  50  of the inner liner  18  may have a thickness ranging from between about 0.1 mm to about 3.0 mm. In a specific embodiment, the liner walls  50  have a thickness of about 0.5 mm. 
     The inner liner  18  is shaped and configured to mate, couple or otherwise be positioned within the external wrapper  22 . The external wrapper  22  includes a plurality of wrapper walls  58  to which a wrapper flange  62  is coupled. The wrapper flange  62  and the liner flange  46  are configured to be coupled when the cabinet  14  is in an assembled configuration. The coupling of the liner flange  46  and the wrapper flange  62  may be performed such that an airtight, or hermetic, seal is formed between the inner liner  18  and the external wrapper  22 . The hermetic seal of the wrapper flange  62  and the liner flange  46  may be achieved through use of adhesives, welding, an elastomeric gasket under compression and/or crimping. The coupling of the liner flange  46  to the wrapper flange  62  may be performed proximate a front flange area  64  ( FIG.  2 A ) of the cabinet  14 . The front flange area  64  may be configured to couple with a door which permits access to an interior of the cabinet  14 . 
     The external wrapper  22  may be formed of and by any of the materials and processes listed above in connection with the inner liner  18 . The wrapper walls  58  of the external wrapper  22  may have a thickness ranging from between about 0.1 mm to about 3.0 mm. In a specific embodiment, the wrapper walls  58  have a thickness of about 0.5 mm. The wrapper walls  58  of the external wrapper  22  may define an injection port  66  and/or a vacuum port  70 . The external wrapper  22  may include one or multiple injection ports  66  and/or vacuum ports  70 . The injection ports  66  and/or vacuum ports  70  may be positioned as illustrated or in a variety of positions about the external wrapper  22 . It will be understood that in alternative embodiments, the injection ports  66  and/or vacuum ports  70  may be disposed on both the external wrapper  22  and inner liner  18 , or solely on the inner liner  18 . The injection port  66  and the vacuum port  70  may be used to access (e.g., to inject an insulator, draw a vacuum and/or perform maintenance within) the gap  26  once the inner liner  18  and the external wrapper  22  are bonded. The injection port  66  and the vacuum port  70  may have a diameter of between about 10 mm and about 50 mm, or between about 12.5 mm and about 25 mm. In various embodiments, the injection port  66  and the vacuum port  70  may have different diameters than one another. Similarly, in embodiments utilizing more than one injection port  66  and vacuum port  70 , the sizes of the injection ports  66  and the vacuum ports  70  may vary. 
     Referring now to  FIG.  1 C , the inner liner  18  and the external wrapper  22  may be joined via a trim breaker  72 . The trim breaker  72  may be formed of a plastic, a metal, a composite and/or insulating materials. The trim breaker  72  may define a liner joint  72 A configured to couple the inner liner  18  to the trim breaker  72 . The trim breaker  72  may also define a wrapper joint  72 B configured to couple the external wrapper  22  to the trim breaker  72 . The liner joint  72 A and the wrapper joint  72 B may be vibration welded, crimped, thermally bonded, adhesively bonded or otherwise coupled to render the gap  26  airtight. The trim breaker  72  may be used to hold the inner liner  18  and the external wrapper  22  together and in place. Use of the trim breaker  72  may provide advantages of resisting thermal bridging between the inner liner  18  and the external wrapper  22  and easing manufacturing. 
     Referring now to  FIG.  2 A , once the inner liner  18  and the external wrapper  22  have been joined and the gap  26  defined, the first insulator  30  and the second insulator  34  may be dispensed into the gap  26 . The gap  26  may have a thickness of between about 12 mm to about 30 mm. The gap  26  may have an air pressure of less than about 1 atm (101,325 Pa, 1013.25 mbar), less than about 0.5 atm (50,662.5 Pa, 506.63 mbar), less than about 0.1 atm (10,132.5 Pa, 101.33 mbar), less than about 0.001 atm (101.325 Pa, 1.0133 mbar) or less than about 0.00001 atm (1.01 Pa, 0.01 mbar). Over the service life of the refrigerator  10  ( FIG.  1 A ), the air pressure within the gap  26  may rise more than about 0.001 atm (101 Pa, 1.01 mbar), greater than about 0.005 atm (506 Pa, 5.06 mbar) or greater than about 0.01 atm (1,013 Pa, 10.13 mbar) due to diffusion and/or permeation of gases into the gap  26  through the inner liner  18  and/or the external wrapper  22 . The first and second insulators  30 ,  34  may be a material configured to have low thermal conductivity. For example, the first and second insulators  30 ,  34  may include precipitated silica, polyurethane foam, fumed silica, silica fume, beads (e.g., of glass, ceramic, and/or an insulative polymer), hollow organic micro/nano spheres, hollow inorganic micro/nano spheres, silica aerogel, nano-aerogel powder, rice husk ash, diatomaceous earth, cenospheres, perlite, glass fibers, polyisocyanurate, urea foam, rice hulls, polyethylene foam, vermiculite, fiberglass and combinations thereof. Optionally, an opacifier (e.g., TiO 2 , SiC and/or carbon black) may be included in the first and/or second insulators  30 ,  34 . Additionally or alternatively, materials configured to change the radiation conduction, flow properties and packing factor of the first and second insulators  30 ,  34  may be introduced. Further, one or more gas (e.g., oxygen, hydrogen, carbon dioxide) and/or moisture getters may be included in the first and second insulators  30 ,  34 . The first and second insulators  30 ,  34  may include the same insulating material as one another, may be substantially the same material, or may be completely different materials. 
     In embodiments where the first and/or second insulators  30 ,  34  include organic spheres, the organic spheres may include polystyrene, polythiophenes, polyethylene, rubber and/or combinations thereof. In embodiments where the first and/or second insulators  30 ,  34  include inorganic spheres, the spheres may include glasses, ceramics and combinations thereof. In embodiments where the first and/or second insulators  30 ,  34  include beads or spheres, the beads or spheres may have an average outer diameter ranging from about 50 nm to about 300 μm, or from about 1 μm to about 300 μm, or from about 50 nm to about 1000 nm. In various embodiments, the diameter size distribution of the spheres is low. Sphere embodiments of the first and/or second insulators  30 ,  34  may be filled with a single gas (e.g., H 2 , O 2 , N 2 , noble gases, volatile organic compounds, CO 2 , SO, SO 2 ) or a mixture of gases (e.g., atmosphere, noble gases, O 2 , SO 2 , SO). The spheres may be sealed and have a gas pressure within the spheres of between about 0.1 atm and about 1.0 atm, or between about 0.2 atm and about 0.5 atm, or between about 0.25 atm and about 0.35 atm. The first and/or second insulators  30 ,  34  are positioned within the gap  26  and in contact with both the wrapper walls  58  and the liner walls  50 . The packing factor of the first and/or second insulators  30 ,  34  within the gap  26  may be greater than about 60%, greater than about 62%, greater than about 65%, or greater than about 70%. 
     In embodiments where the first and/or second insulators  30 ,  34  include fumed silica, the fumed silica may be hydrophobic and/or hydrophilic. The fumed silica may have a particle size ranging from less than about 0.005μ to greater than about 1.0μ. The fumed silica may have a density of between about 32 kg/m 3  to about 80 kg/m 3 . When positioned within the gap  26 , the fumed silica may have a density between about 50 kg/m 3  to about 300 kg/m 3 , or between about 80 kg/m 3  to about 250 kg/m 3  or between about 150 kg/m 3  to about 200 kg/m 3 . 
     The first and second insulators  30 ,  34  are configured not only to thermally insulate the inner liner  18  from the external wrapper  22 , but also to resist the inward directed force of the atmosphere on the lower than atmosphere pressure of the gap  26 . Atmospheric pressure on the inner liner  18  and the external wrapper  22  may cause distortions which are unsightly and may lead to a rupture in either of the inner liner  18  or the external wrapper  22  thereby causing a loss of vacuum in the gap  26 . Further, drawing the vacuum in the gap  26  may cause an impact or shock loading of the first and second insulators  30 ,  34  as the inner liner  18  and the external wrapper  22  contract around the first and second insulators  30 ,  34 . Accordingly, the first and second insulators  30 ,  34  should have sufficient crush resistance to resist deformation of the inner liner  18  and the external wrapper  22  due to a pressure gradient between the atmosphere and an air pressure of the gap  26 . 
     The first insulator  30  may be positioned within, and proximate to, the front flange area  64  of the cabinet  14  and the second insulator  34  may fill the rest of the gap  26 . In the depicted embodiment, a filter  74  is positioned between the first insulator  30  and the second insulator  34 . The filter  74  may be made of paper, a polymeric material, a ceramic and/or a metal. The filter  74  may be porous, solid and/or coupled to the inner liner  18  and/or the external wrapper  22 . Use of the filter  74  may resist or prevent the migration and mixing of the first and second insulators  30 ,  34  such that the first and second insulators  30 ,  34  remain segregated. The front flange area  64 , due to its thinner cross section and being surrounded by atmosphere on three sides, may suffer from a thermal, or heat, bridging effect. Such a thermal bridging across the front flange area  64  may result in an overall reduced efficiency of the refrigerator  10 . Accordingly, in various embodiments the first insulator  30  may have a higher insulating property than the second insulator  34 . In such an embodiment, the higher insulating property of the first insulator  30  may be sufficient to reduce, or eliminate any thermal bridging taking place through the front flange area  64 . 
     Referring now to  FIGS.  2 A and  2 B , as explained above, the gap  26  within the cabinet  14  may undergo a pressure increase over the service life of the refrigerator  10  due to permeation and/or diffusion of gases. As such, selection of the first and second insulators  30 ,  34  may account for the expected change in pressure within the gap  26 . As can be seen in  FIG.  2 B , fumed silica undergoes the smallest increase in thermal conductivity over an expected pressure change range (e.g., between about 1 mbar and about 10 mbar), followed by precipitated silica. As such, use of fumed silica as the first insulator  30  and precipitated silica and/or combinations of insulators (e.g., precipitated silica and spheres) as the second insulator  34  may not only reduce thermal bridging across the front flange area  64  while the gap  26  is at manufactured pressure, but also over the service life of the refrigerator  10 . 
     Referring now to  FIGS.  3 A and  3 B , one embodiment of a first method  80  of inserting the first and second insulators  30 ,  34  within the gap  26  is depicted. The first method  80  includes step  84 , step  88 , step  92 , step  94  and step  96 . In step  84 , the inner liner  18  is positioned within the external wrapper  22  as explained in greater detail above. The liner flange  46  and the wrapper flange  62  may be bonded so as to make the gap  26  airtight. Next, step  88  of drawing a vacuum may be performed. A vacuum, or negative pressure relative to atmospheric pressure, is generated within the gap  26 . The vacuum is created by drawing the air out of the gap  26  through the at least one vacuum port  70 . A pump or other suitable vacuum sources may be connected to the vacuum port  70  to facilitate drawing the vacuum. Additionally or alternatively, the first method  80 , or any of its steps, may be performed within a vacuum chamber  98  to provide the vacuum to the gap  26 . 
     Next, step  92  of injecting the first insulator  30  into the gap  26  is performed. 
     Injection of the first insulator  30  into the gap  26  may be accomplished by feeding the first insulator  30  into a hopper  100  which in turn supplies the first insulator  30  to a transfer mechanism  104 . The transfer mechanism  104  may be a powder pump, a vacuum transfer device, pneumatic pump, flexible screw conveyor, auger feeder and/or other devices capable of transferring or moving the first and second insulators  30 ,  34 . The transfer mechanism  104  pumps or otherwise injects the first insulator  30  into the gap  26  of the cabinet  14  ( FIG.  1 A ). The transfer mechanism  104  may utilize fluidization of the first insulator  30  to move the first insulator  30  into the gap  26 . The transfer mechanism  104  may dispense the first insulator  30  into the cabinet  14  with or without pressure. Use of the transfer mechanism  104  allows the first insulator  30  to be inserted into the gap  26  without any densification or compaction, while also providing an easy and efficient means of inserting the first insulator  30 . Once the first insulator  30  has sufficiently filled the front flange area  64  of the cabinet  14  and optionally been leveled off, the filter  74  may be placed on top of the first insulator  30  and optionally coupled to the inner liner  18  and external wrapper  22 . Next, step  94  of injecting the second insulator  34  is performed. Injection of the second insulator  34  may be performed in substantially the same manner as injection of the first insulator  30  is carried out in step  92 . In other embodiments, the second insulator  34  may be dispensed or injected under different conditions that produce a different packing factor or density of the second insulator  34  relative to the first insulator  30 . 
     Next, step  96  of vibrating at least one of the inner liner  18  and the external wrapper  22  is performed. Vibration of the inner liner  18  and/or the external wrapper  22  may cause the first insulator  30  to increase its packing factor. During steps  84 ,  88 ,  92 ,  94  and/or  96  the inner liner  18  and/or external wrapper  22  may be supported by one or more supports  106  such that relative motion between the inner liner  18  and the external wrapper  22  is minimized or prevented. The supports  106  may allow the thickness of the gap  26  to remain constant through filling and vibration. It will be understood that although method  80  was described in a specific order, the steps may be performed in any order or simultaneously without departing from the spirit of this disclosure. 
     Referring now to  FIGS.  4 A and  4 B , depicted is a second method  108  of dispensing the insulator  30  within the gap  26  between the inner liner  18  and the external wrapper  22 . The second method  108  includes step  112 , step  116 , step  118 , step  120  and step  124 . The second method  108  begins with step  112  of positioning the inner liner  18  within the external wrapper  22  and sealing the gap  26 , as disclosed above. Next step  116  of dispensing the first insulator  30  within the gap  26  is performed. In the second method  108 , dispensing of the first insulator  30  into the gap  26  may be accomplished through a back aperture  132 . The back aperture  132  may take a variety of shapes (e.g., square, rectangular, circular, oblong, and combinations thereof) and sizes which are configured to allow the first insulator  30  to be poured or otherwise dispensed into the gap  26 . The first insulator  30  may be dispensed into the gap  26  between the inner liner  18  and the external wrapper  22  via the transfer mechanism  104  ( FIG.  3 A ), pouring the first insulator  30 , or manual application. In embodiments of the cabinet  14  ( FIG.  1 A ) where the external wrapper  22  includes the back aperture  132 , the external wrapper  22  may not include the injection port  66  ( FIG.  3 A ). Optionally, step  116  may be performed while at least one of the inner liner  18  and the external wrapper  22  are vibrated. Vibration of the inner liner  18  and/or the external wrapper  22  may facilitate in shaking or vibrating the first insulator  30  into its maximum packing factor and facilitate a more complete filling of the gap  26 . Optionally, once the front flange area  64  is sufficiently filled with the first insulator  30  and optionally the first insulator  30  has been leveled off, the filter  74  may be placed on the first insulator  30  as described above. 
     Once the front flange area  64  of the gap  26  between the inner liner  18  and the external wrapper  22  is filled with the insulator  30  and sufficiently packed with the first insulator  30 , step  118  of dispensing the second insulator  34  is performed. Dispensing of the second insulator  34  may be accomplished in a substantially similar manner to that described in connection with the first insulator  30  in step  116 . Next, step  120  of positioning a back plate  142  over the back aperture  132  is performed. The back plate  142  may be constructed of the same or similar material as the external wrapper  22 , or a different material. Once the back plate  142  is positioned over the back aperture  132 , the back plate  142  is sealed to the external wrapper  22  to form an airtight, or hermetic, seal. After step  120  is completed, step  124  of drawing a vacuum within the gap  26  is performed. The vacuum may be drawn through the vacuum port  70  ( FIG.  3 A ) of the external wrapper  22 . Additionally or alternatively, method  108 , or individual steps thereof, may be performed within the vacuum chamber  98  such that drawing a vacuum may not be necessary, or less vacuum can be drawn. Further, the second method  108  may utilize the supports  106  to resist relative motion of the inner liner  18  and the external wrapper  22 . It will be understood that steps of the first and second methods  80 ,  108  may be omitted, combined, mixed and matched, or otherwise reordered without departing from the spirit of this disclosure. 
     Use of the present disclosure may offer several advantages. For example, use of the present disclosure allows for the formation of vacuum insulated cabinets  14 , panels, and structures without noticeable deformation of the inner liner  18  and the external wrapper  22 . By filling the gap  26 , deformation of the inner liner  18  and the external wrapper  22  from the pressure differential between the atmosphere and the gap  26  is resisted by the first and second insulators  30 ,  34 . Vacuum insulated cabinets  14 , panels and structures may provide enhanced insulative properties as compared to traditional foam filled insulating structures in addition to a reduced size (e.g., thickness decrease of greater than about 55%, 60% or 70%). Additionally, use of the disclosure may allow for the construction of a less dense cabinet  14  while also providing increased rigidity due to the use of the first and second insulators  30 ,  34 . Further strategic use of the first insulator  30  in more critical insulation areas (e.g., in the front flange area  64 , in corners and/or thin locations) and the second insulator  34  in the rest of the cabinet  14  may allow for a cost savings in embodiments where the first insulator  30  is more expensive (e.g., fumed silica) than the second insulator  34  (e.g., precipitated silica). Even further, in embodiments where the first insulator  30  has a lower increase in thermal conductivity per unit pressure increase than the second insulator  34 , use of the first insulator  30  proximate the front flange area  64  allows for a greater resistance to thermal bridging as the pressure within the gap  26  increases over the service life of the refrigerator  10 . It will be understood that although the disclosure was described in terms of a refrigerator, the disclosure may equally be applied to coolers, ovens, dishwashers, laundry applications, water heaters, household insulation systems, ductwork, piping insulation, acoustical insulation and other thermal and acoustical insulation applications. 
     In this specification and the appended claims, the singular forms “a,” “an” and “the” include plural reference unless the context clearly dictates otherwise. For the purposes of describing and defining the present teachings, it is noted that the terms “substantially” and “approximately” are utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The terms “substantially” and “approximately” are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. 
     It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present disclosure, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.