Patent Description:
A refrigerator appliance typically includes a cabinet having an inner liner defining one or more compartments for storing food items, and an outer shell surrounding the inner liner that defines an exterior of the cabinet Moreover, foam insulation is typically injected into a space between the inner liner and outer shell, and then cured. The foam will expand during the curing process such that once curing is complete, the liner will be held in place within the outer shell by the cured foam.

In some cases, refrigerator components (e.g., wall grommets, electrical boxes, air ducts, water conduits, wall anchors, etc.) are attached to an exterior surface of the inner liner with tapes or glues before foam is injected into the cabinet. For example, an air duct can be attached to the exterior surface of the liner with tape or glue such that the air duct is aligned with an aperture of the liner and an interior of the air duct communicates with an interior of the liner through the aperture. The foam will similarly hold these refrigerator components in place once injected and cured.

However, tapes and glues can be expensive and time consuming to apply, particularly if an interface between the refrigerator component and the liner has a complicated geometry. Moreover, the bond formed by tapes or glues can be rather weak, leading to other problems. For example, the refrigerator components can become displaced prior to or during injection and curing of the insulating foam. As another example, the foam during injection can leak through the taped or glued interface of a refrigerator component and the liner into an interior of the refrigerator component (e.g., air duct) and/or liner. Prior art is shown in <CIT>, which discloses a method for assembling components onto an inner liner before foaming; <CIT>, which discloses a refrigerator structure with an inner liner, a non self-supporting outer liner and a foam between the inner and outer liner; and <CIT>, which discloses mounting of refrigerator components on a mold body, whereafter a liner material is applied to the mold body and refrigerator components to build an inner liner with positioned components after removal from the mold.

Further relevant prior art is disclosed in documents <CIT> and <CIT>.

The invention is disclosed in the independent claims <NUM> and <NUM> and further embodiments are disclosed in the dependent claims to respective independent claim.

In accordance with the invention, a method of manufacturing a refrigerator appliance
according to claim <NUM> includes a step of providing a liner and a refrigerator component for attachment to the liner. The liner defines a compartment for storing food items and includes a liner contact structure. The refrigerator component includes component contact structure. The method further includes a staging step that includes arranging the liner and refrigerator component such that the liner contact structure and component contact structure are in direct contact with each other under pressure, wherein the liner and refrigerator component as arranged form a staged assembly. Moreover, the method includes a welding step that includes applying ultrasonic energy to the staged assembly to weld the liner and refrigerator component together at an interface of the component contact structure and liner contact structure, wherein the liner and refrigerator component as welded together form a liner assembly.

It is to be understood that both the foregoing general description and the following detailed description present example and explanatory embodiments. The accompanying drawings are included to provide a further understanding of the described embodiments and are incorporated into and constitute a part of this specification. The drawings illustrate various example embodiments.

The foregoing and other aspects of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which:.

Example embodiments are described and illustrated in the drawings.

<FIG> show embodiments according to the present invention, whereas <FIG> show embodiments being useful for understanding the invention, which are outside the subject-matter of the claims. Still further, in the drawings, the same reference numerals are employed for designating the same elements or steps.

With reference to <FIG>, an example refrigerator appliance <NUM> according to claim <NUM> is illustrated that includes a cabinet <NUM> comprising a liner <NUM> and an outer shell <NUM> that surrounds the liner <NUM>. The liner <NUM> can include one or more walls that define one or more compartments for storing food items. For instance, the liner <NUM> in the illustrated embodiment includes a first set of walls <NUM> including a bottom wall 18a, a pair of side walls 18b, a rear wall 18c, and a top wall <NUM>d that collectively define a first compartment <NUM>. The liner <NUM> also includes a second set of walls <NUM> including a bottom wall <NUM>a, a pair of side walls <NUM>b, a rear wall <NUM>c, and a top wall <NUM>d that collectively define a second compartment <NUM> arranged below the first compartment <NUM>. The first compartment <NUM> corresponds to a fresh-food compartment that can be maintained at temperature(s) between <NUM> and <NUM>, while the second compartment <NUM> corresponds to a freezer compartment that can be maintained at temperature(s) below <NUM>° C.

The appliance <NUM> can further include one or more doors <NUM> for providing selective access to its compartment(s). For example, the appliance <NUM> in the illustrated embodiment has a pair of French-doors <NUM>a, <NUM>b coupled to its cabinet <NUM> for providing selective access to the first compartment <NUM>. The appliance <NUM> can further include a third door (not shown) for its second compartment <NUM> that is attached to a slidable drawer. However, it is to be appreciated that the appliance <NUM> can include any number, type, and arrangement of compartments and doors without departing from the scope of this disclosure.

Foam insulation is injected into space(s) between the liner <NUM> and outer shell <NUM> of the appliance <NUM> to improve insulation of the liner's compartment(s). With reference to <FIG>, an example method <NUM> according to claim <NUM> for manufacturing the appliance <NUM> according to claim <NUM> in <FIG> and improving its foam insulation process will now be described. As shown in <FIG>, the method <NUM> includes a providing step <NUM>, a staging step <NUM>, a welding step <NUM>, and a cabinet assembly step <NUM>, which are described below in further detail.

Turning to <FIG>, the providing step <NUM> includes providing the liner <NUM> of the appliance <NUM> and a refrigerator component <NUM> for attachment to the liner <NUM>. The liner <NUM> defines at least one aperture extends through its wall(s) and can enable service utilities to pass through the liner <NUM> and into its compartment(s), such as electrical cables, liquid tubes, refrigerant tubes, etc. For instance, the liner <NUM> in the illustrated embodiment includes a single aperture <NUM> that is substantially rectangular in shape (see <FIG>) and extends through its rear wall <NUM>c. However, this aperture <NUM> may have other shapes and/or be located in other walls of the liner <NUM> in some examples. Moreover, the liner <NUM> may include additional apertures in some examples.

The liner <NUM> also includes a liner contact structure <NUM> that, as discussed further below, is placed in direct contact with corresponding structure of the refrigerator component <NUM> when attaching the liner <NUM> and refrigerator component <NUM> together. In the present embodiment, the liner contact structure <NUM> comprises a flat, continuous surface <NUM> on a rear side of the rear wall <NUM>c that circumscribes the aperture <NUM> (see <FIG>). In particular, the surface <NUM> is an annular surface having an inner perimeter <NUM> that corresponds to a perimeter of the aperture <NUM>, and an outer perimeter <NUM> that is spaced outwardly from the inner perimeter <NUM>. However, the surface <NUM> may be curved, angled, and/or stepped in some examples, and may extend only partially about the aperture <NUM>. Indeed, the liner contact structure <NUM> can comprise any configuration of structure (e.g., surface, edge, projection, recess, ribs, etc.) that is placed in direct contact with corresponding structure of the refrigerator component <NUM> when attaching the liner <NUM> and refrigerator component <NUM> together.

The refrigerator component <NUM> can correspond to a variety of different components for attachment to the liner <NUM> such as, for example, a wall grommet, an electrical box, an air duct, a water conduit, a refrigerant conduit, or a wall anchor. The refrigerator component <NUM> in the illustrated example is an electrical box comprising a main body <NUM> (see <FIG>) that defines an interior space <NUM> and an opening <NUM> for providing access to the interior space <NUM>. The main body <NUM> can further define one or more apertures (not shown) that can permit wiring to fed into the interior space <NUM>. Moreover, the refrigerator component <NUM> further includes a flange <NUM> attached to the main body <NUM> that extends about the entire perimeter of the opening <NUM>. Preferably, the refrigerator component <NUM> is a unitary or monolithic body to thereby limit the potential for foam leakage after installation upon the liner <NUM>. However, the refrigerator component <NUM> can comprise a variety of different configurations without departing from the scope of the disclosure.

The refrigerator component <NUM> includes a component contact structure <NUM> that is placed in direct contact with the liner contact structure <NUM> of the liner <NUM> when attaching the liner <NUM> and refrigerator component <NUM> together. In the present embodiment, the component contact structure <NUM> is defined by the flange <NUM> of the refrigerator component <NUM>, and comprises a plurality of ribs <NUM> that are spaced about the perimeter of the opening <NUM> (see <FIG> & <FIG>) and stand proud of the flange <NUM> surface. Each rib <NUM> defines a contact edge <NUM> that, as discussed further below, can be arranged in direct contact with the contact structure <NUM> (e.g., surface <NUM>) of the liner <NUM> when attaching the liner <NUM> and refrigerator component <NUM> together. However, the ribs <NUM> can be arranged differently or have different shapes in other examples. Moreover, the component contact structure <NUM> in some examples can comprise a contact surface in addition or in alternative to the ribs <NUM>, which can be arranged in direct contact and flush with the contact surface <NUM> of the liner <NUM> when attaching the liner <NUM> and refrigerator component <NUM>. Indeed, the component contact structure <NUM> can comprise any configuration of structure (e.g., surface, edge, projection, recess, ribs, etc.) that can be placed in direct contact with the contact structure <NUM> of the liner <NUM> when attaching the liner <NUM> and refrigerator component <NUM> together.

The liner <NUM> and refrigerator component <NUM> preferably comprise the same type of material and more preferably, the same type of plastic (i.e., polyethylene terephthalate, high-density polyethylene, polyvinyl chloride, low-density polyethylene, polypropylene, or polystyrene). For instance, the liner <NUM> and refrigerator component <NUM> in the illustrated embodiment both consist of polystyrene and more specifically, high-impact polystyrene. Whichever material is used for the liner <NUM> and refrigerator component <NUM>, the grades of material used for the two can be different from each other, with different specific gravities and melt flows. Moreover, the material of the liner <NUM> and material of the refrigerator component <NUM> preferably have a difference in melt temperature of <NUM>° C or less and more preferably, <NUM>° C or less. In one example, although the same type of plastic, one of the components can be made of an injection molding grade plastic while the other component can be made of a thermoforming, roto-molding, or blow-molding grade plastic.

The liner <NUM> and refrigerator component <NUM> provided in the providing step <NUM> can be formed in advance using a variety of different processes. For example, the liner <NUM> can be formed via thermoforming by heating a plastic sheet and then shaping the heated sheet in a mold. Such thermoforming can be a relatively low-cost method of forming the liner <NUM>. Meanwhile, the refrigerator component <NUM> can be formed via injection molding, which can be a more expensive but enables more complex shapes to be formed for the refrigerator component <NUM>. In other examples, the refrigerator component <NUM> may be formed by an extrusion process. The liner <NUM> and refrigerator component <NUM> can be formed by a variety of different processes without departing from the scope of the disclosure. Moreover, in some examples, the providing step <NUM> can actually include a step of forming the liner <NUM> and/or refrigerator component <NUM> using the processes described above.

Turning to <FIG>, the staging step <NUM> includes arranging the liner <NUM> and refrigerator component <NUM> such that the liner contact structure <NUM> and component contact structure <NUM> are in direct contact with each other under pressure, thereby defining an interface <NUM> between the liner <NUM> and refrigerator component <NUM> (for the purposes of this disclosure, an "interface" between components refers to the area(s) at which the two components directly contact each other and/or are welded together). The liner <NUM> and refrigerator component <NUM> as arranged will collectively form a staged assembly <NUM>, which can be further processed in later steps.

In the illustrated embodiment, the liner <NUM> and refrigerator component <NUM> are arranged such that the ribs <NUM> of the refrigerator component <NUM> directly contact the surface <NUM> of the liner <NUM> at their edges <NUM>, and form the only points of contact between the liner <NUM> and refrigerator component <NUM>. Moreover, the liner <NUM> and refrigerator component <NUM> are arranged such that their interface <NUM> circumscribes the aperture <NUM> of the liner <NUM> and is broken up by the spacing between adjacent ribs <NUM>. However, the interface <NUM> in other examples can be continuous about the perimeter of the aperture <NUM>.

The liner <NUM> and refrigerator component <NUM> can be arranged during the staging step <NUM> by nesting the liner <NUM> and refrigerator component <NUM> within a rigid fixture <NUM> (see <FIG>), which will support the liner <NUM> and refrigerator component <NUM> in their arranged positions and limit relative movement among the parts. However, the liner <NUM> and refrigerator component <NUM> can be arranged together using other means including, for example, manual force and/or clamps.

As shown in <FIG>, the welding step <NUM> comprises applying ultrasonic energy to the staged assembly <NUM> while the interface <NUM> of the liner <NUM> and refrigerator component <NUM> is under pressure (e.g., <NUM>-<NUM> p. , such as about <NUM> p. ) to thereby ultrasonically weld the liner <NUM> and refrigerator component <NUM> together at the interface <NUM>. In particular, a sonotrode <NUM> can be used to apply ultrasonic energy to the staged assembly <NUM> at a predetermined frequency and amplitude (e.g., <NUM>-<NUM>, such as <NUM> at about <NUM> - <NUM> in. ), which will generate vibrations at the pressured interface <NUM> of the liner <NUM> and refrigerator component <NUM>. For embodiments in which the liner <NUM> and refrigerator component <NUM> comprise plastic, these vibrations will generate friction that causes the liner <NUM> and refrigerator component <NUM> to melt at their points of contact and weld together. With metals, however, welding will occur due to high-pressure dispersion of surface oxides and local motion of the materials.

In the illustrated embodiment, the sonotrode <NUM> is arranged to press directly against the liner <NUM> and apply ultrasonic energy directly to the liner <NUM>. Such pressure of the sonotrode <NUM> against the liner <NUM> will generate corresponding pressure at the interface <NUM> of the liner <NUM> and refrigerator component <NUM> to facilitate the welding process. However, the sonotrode <NUM> may be arranged to press directly against the refrigerator component <NUM> in other examples. Moreover, the sonotrode <NUM> may be arranged to apply ultrasonic energy and pressure indirectly to the liner <NUM> and/or refrigerator component <NUM> in some examples.

Preferably, the liner <NUM> and/or refrigerator component <NUM> are configured to concentrate the ultrasonic energy supplied by the sonotrode <NUM> at their interface <NUM>. For example, as discussed above, the refrigerator component <NUM> in the illustrated embodiment comprises a plurality of ribs <NUM> defining edges <NUM> that can be arranged in direct contact with the surface <NUM> of the liner <NUM> to form the staged assembly <NUM>. These edges <NUM> will preferably be the only points of contact between the liner <NUM> and refrigerator component <NUM>. By contacting the surface <NUM> of the liner <NUM> only with the edges <NUM> of the ribs <NUM>, this will limit the initial contact area (i.e., interface <NUM>) between the liner <NUM> and refrigerator component <NUM>, thereby concentrating the ultrasonic energy supplied by the sonotrode <NUM> to a relatively small area. Such concentration of the ultrasonic energy will quickly heat the liner <NUM> and refrigerator component <NUM> at their interface <NUM> and facilitate initiation of the weld.

Once welded together, the liner <NUM> and refrigerator component <NUM> will form a unitary, integrated liner assembly <NUM> (see <FIG> & <FIG>) having a hermetic seal <NUM> at the interface <NUM> of the liner <NUM> and refrigerator component <NUM>. The hermetic seal <NUM> is continuous and extends about the entire perimeter of the liner aperture <NUM>.

As shown in <FIG>, the cabinet assembly step <NUM> can include arranging the liner assembly <NUM> within the outer shell <NUM> and then injecting an expanding, insulating foam <NUM> into the space between the liner assembly <NUM> and the outer shell <NUM>. In the illustrated embodiment, the outer shell <NUM> comprises a piece of sheet metal that is bent to form a pair of side walls <NUM>b and a rear wall <NUM>c that collectively form a space <NUM> for receiving the liner assembly <NUM>. The sheet metal can be bent to form additional and/or alternative walls (e.g., a top wall) in some examples. Moreover, in some examples, the outer shell <NUM> can comprise multiple walls that are separately attached to each other to form the outer shell <NUM>. For instance, in some examples a piece of sheet metal can be bent to form side walls and a top wall, while a separate bottom wall and rear wall are separately attached to the bent sheet metal to form the outer shell <NUM>. The outer shell <NUM> can comprise any configuration of walls forming a space for receiving the liner assembly <NUM>.

While the liner assembly <NUM> is arranged within the space <NUM>, the foam <NUM> can be injected into the portions of the space <NUM> between the liner assembly <NUM> and outer shell <NUM>, and then cured. The foam <NUM> will expand during the curing process such that once curing is complete, the liner assembly <NUM> will be held in place within the outer shell <NUM> by the cured foam <NUM>.

By attaching the refrigerator component <NUM> to the liner <NUM> via ultrasonic welding as described above, various advantages can be realized over prior art methods of attaching a refrigerator component to a liner with tapes or glues. For example, the material costs and labor costs of applying tape or glue to their interface <NUM> can be eliminated. Although ultrasonic welding will incur its own special costs for welding equipment and labor, such costs can be mitigated and scaled through automation and mass production, whereas automation is more difficult to implement when dealing with tapes or glues.

Moreover, the bond strength between the refrigerator component <NUM> and liner <NUM> is increased, thereby preventing displacement of the refrigerator component <NUM> during injection and curing of the foam <NUM>. Still further, the hermetic seal <NUM> between the refrigerator component <NUM> and liner <NUM> can prevent the injected foam from leaking into the interior spaces of the liner <NUM> and refrigerator component <NUM>. In contrast, in embodiments wherein the refrigerator component <NUM> and liner <NUM> are attached to each other with glues or tapes, the bond strength is weaker and injected foam can leak through the interface of the refrigerator component <NUM> and liner <NUM>.

For example, as discussed below, various tests were performed to compare the bonding strength of samples bonded together with ultrasonic welding versus the bonding strength of samples bonded together with traditional methods using glue or tape, which confirmed that the samples bonded together via ultrasonic welding had a significantly higher bonding strength.

More specifically, a group of <NUM> welded samples was produced in which for each sample, two flat substrates comprising thermoformed high-impact polystyrene were welded together using a Hermann Ulstrasonics™ HSG Digital <NUM> hand welder. The welder applied ultrasonic energy at an amplitude of <NUM> and a frequency of <NUM> while the two substrates were held together under a pressure of <NUM> p. The final welded interface between the two substrates was approximately <NUM> sq. inch in area.

Meanwhile, a group of <NUM> taped samples was produced in which for each sample, two flat substrates comprising thermoformed high-impact polystyrene using double-sided tape (i.e., Duraco® Dubl Kote® acrylic white tape). The interface between the tape and each substrate was approximately <NUM> sq. inch in area.

Lastly, a group of <NUM> glued samples was produced in which for each sample, two flat substrates comprising thermoformed high-impact polystyrene were glued together with adhesive (i.e., Reynco <NUM>-<NUM> SM adhesive manufactured by The Reynolds Company™). The interface between the adhesive and each substrate was approximately <NUM> sq. inch in area.

The tensile strength of the bond for each sample above was then tested using an Instron® Model <NUM> Table Mounted Materials Testing System, Capacity <NUM> kN. <FIG> shows a table listing the tensile strengths observed for each sample, as well as the mean, standard deviation, and variance of tensile strength for each group.

From here, a statistical analysis of the results in <FIG> was performed using a two-sample, two-tailed t-test to determine if there was a statistically significant difference in tensile strength between the group of welded samples and the groups of glued and taped samples. That is, for each comparison of groups (i.e., welded group versus glued group and welded group versus taped group), a t value was calculated as follows: <MAT> wherein X<NUM> and X<NUM> are the mean tensile strengths of the respective groups, <MAT> and <MAT> are the variances in tensile strength for the respective groups, and n<NUM> and n<NUM> are sample sizes for the respective groups.

The calculated t value for the welded group versus taped group was <NUM>, while the calculated t value for the welded group versus glued group was <NUM>. These calculated t values were then compared against a critical t value of <NUM> provided in the Student's t Distribution Table shown in <FIG> for a <NUM>-Tail Confidence Level of <NUM>% with <NUM> degrees of freedom df (the degrees of freedom df being equal to sample size n minus <NUM>). Because the calculated t values of <NUM> and <NUM> were both higher than the critical t value of <NUM>, this means that there was a statistically significant difference in tensile strength between the group of welded samples and the groups of glued and taped samples, with a <NUM>% confidence level. Indeed, the calculated t values of <NUM> and <NUM> were also higher than the critical t value of <NUM> provided in the Student's t Distribution Table for a <NUM>-Tail Confidence Level of <NUM>% with <NUM> degrees of freedom df , meaning that there was a statistically significant difference in tensile strength between the groups with a <NUM>% confidence level.

Separately, a p-value was also calculated for each comparison of groups using Excel. The calculated p-value for the welded group versus taped group was <NUM>×<NUM>-<NUM>, while the calculated p-value for the welded group versus glued group was <NUM>×<NUM>-<NUM>. Thus, both calculated p-values were significantly smaller than a critical p-value of <NUM>, further confirming that there was a statistically significant difference in tensile strength between the group of welded samples and the groups of glued and taped samples.

Thus, it can be confidently stated that the ultrasonic welding method described above improves the bond strength between the refrigerator component <NUM> and liner <NUM> compared to traditional methods using tapes or adhesive.

Turning to <FIG>, another aspect of an appliance <NUM> will now be described. The liner <NUM> of the appliance <NUM> can define a first (upper) compartment <NUM> and a second (lower) compartment <NUM>, and the appliance <NUM> can be manufactured by arranging the liner <NUM> within the outer shell <NUM> and then injecting insulating foam <NUM> into spaces between the liner <NUM> and outer shell <NUM>. As shown in <FIG>, the liner <NUM> in some examples can include a mullion portion <NUM> between the two compartments <NUM>, <NUM>, and a front flange <NUM> that circumscribes the upper and lower compartments <NUM>, <NUM>. Various cutouts (e.g., holes, openings, etc.) <NUM> can be formed at the corners of the flange <NUM> and near the ends of the mullion portion <NUM>. Additionally, a plurality of apertures <NUM> can be provided along the mullion portion <NUM>.

Before the insulating foam <NUM> is injected into spaces between the liner <NUM> and outer shell <NUM>, one or more cover panels (not shown) can be arranged along and in front of the mullion portion <NUM> and flange <NUM> of the liner <NUM> to cover the mullion portion <NUM> and flange <NUM> (and their associated cutouts <NUM> and apertures <NUM>). A hot melt adhesive (e.g., Kizen® FORCE adhesive) can then be injected in a melted state with pressure from a rear side of the flange <NUM> through its cutouts <NUM>, thereby permeating into corresponding spaces located in front of the cutouts <NUM> that are surrounded and defined by the flange <NUM>, outer shell <NUM>, and cover panel(s). The adhesive once cooled will harden and glue the flange <NUM> to the outer shell <NUM> and cover panel(s) at these locations, thereby adding structural rigidity to the appliance <NUM>. Moreover, the adhesive will provide a seal that obstructs air from entering the appliance <NUM> at these joints of the liner <NUM>, outer shell <NUM>, and cover panel(s).

Once the adhesive is cooled the insulating foam <NUM> can be injected into spaces behind the mullion portion <NUM> and flange <NUM> of the liner <NUM>. The apertures <NUM> of the mullion portion <NUM> will permit the injected to foam to permeate through the apertures <NUM> into the space between the mullion portion <NUM> and cover panel(s). This will help reduce sweating on the cover panel(s) mounted in front of the mullion portion <NUM>.

Claim 1:
A method of manufacturing a refrigerator appliance (<NUM>), comprising:
a step of providing a liner (<NUM>) that defines a compartment (<NUM>, <NUM>) for storing food items and an aperture (<NUM>) extending through the liner, the liner including a liner contact structure (<NUM>), and
a refrigerator component (<NUM>) for attachment to the liner, the refrigerator component including a component contact structure,
a staging step that includes arranging the liner and the refrigerator component such that the liner contact structure and the component contact structure are in direct contact with each other under pressure and the interface of the component contact structure and the liner contact structure circumscribes the aperture, wherein the liner and the refrigerator component as arranged form a staged assembly;
a welding step that includes applying ultrasonic energy to the staged assembly to weld the liner and the refrigerator component together at an interface of the component contact structure and the liner contact structure, wherein the liner and the refrigerator component as welded together form a liner assembly; and
characterized in that a hermetic seal is formed at the interface of the liner and the refrigerator component by the welding step, wherein the hermetic seal is continuous and extends about the entire perimeter of the aperture.