Patent Description:
Since the <NUM>'s refrigeration appliance cabinets (including free-standing and "built-in" refrigerators, freezers, combined refrigerator-freezers, cooling drawer-type refrigerators, wine cabinets and chest freezers) have been manufactured with "in situ" foamed polyurethane (PU) insulation. This construction usually has a sheet steel "wrapper" or skin on the outside, either a steel or a plastics (polystyrene-based or sheet steel) liner on the inside, and a rigid PU foam in a sandwich construction between the outer wrapper and the inner liner. The outer sheet steel wrapper was typically folded to produce a forward-facing flange that was welded at the corners. With the drive to make refrigeration appliances more cost-efficient, the sheet steel outer panels have become thinner and the welding of the corners of forward facing flanges has been eliminated. Thus the modern refrigeration appliance cabinet relies on the sandwich construction of the outer wrapper, foam and inner liner for its structural integrity. This may be satisfactory for short-term loads, but the long-term loading from the door and food placed in shelving on an inner side of the door will force the cabinet structure to creep due to shear deflection of the foam, allowing the door to drop or droop relative to the cabinet. As the door droops, misalignment with the forward-facing cabinet flange occurs such that a door seal may not engage with the flange over at least a part of its extent and cold air may escape from a cooling compartment or compartments formed by the liner. The problem is exacerbated in tall or wide refrigeration appliance cabinets which may have a heavier door and carry more weight in the door, presenting a greater force acting to deform the refrigeration appliance cabinet. Also, there is a modern trend towards "built-in" appliances which include an additional, and often heavy, door panel attached to the outside of the cabinet door so that the appliance may match surrounding cabinetry thus accentuating door droop.

This door drop is usually countered by adding structural steel to the perimeter of the cabinet, behind the forward-facing flange. The structural steel has the disadvantage that it presents a thermal heat flow path that allows heat leakage into the cabinet, reducing operational efficiency.

<CIT> discloses a refrigerator or freezer having a reinforcement frame about its open face. <CIT> discloses a refrigerator having a top plate which is stepped-down to provide a machine room for housing a compressor. <CIT> discloses a refrigerated cabinet structure in which side walls of a refrigerating equipment space, at the base of the cabinet, are formed by an extension of the sheet metal side walls of the cabinet. The features of the preamble of claim <NUM> are known from <CIT>.

It is an object of the present invention to provide an improved refrigeration appliance that will go at least some way towards overcoming at least some of the above-mentioned disadvantages, or which will provide the industry or public with a useful choice.

In a first aspect, the invention consists in a refrigeration appliance comprising:.

In some embodiments, the insulated cabinet comprises an inner liner and an insulating material between the outer skin and inner liner.

In some embodiments, the torsionally stiff structure forms a plinth for the insulated cabinet.

In some embodiments, the torsionally stiff structure comprises a <NUM>-dimensional structure surrounding a central volume.

In some embodiments, the torsionally stiff structure comprises six sides wherein each side is either closed so that access to the central volume via that side is prevented, or open so that access to the central volume via that side is possible.

According to the invention, the box has one open side and the box is fixed to the insulated cabinet so that an open side of the box is closed by a closed face of the insulated cabinet, the closed face of the insulated cabinet and the box forming the torsionally stiff structure.

In some embodiments, the box has an open top side and is attached to the bottom closed face of the insulated cabinet so that the open top side of the box is closed by the bottom closed face of the insulated cabinet, the bottom closed face of the insulated cabinet and the box forming the torsionally stiff structure.

In some embodiments, the sheet metal box has a front side, and comprises at least one gusset at a substantially open front side, each gusset attached between adjacent sides of the box.

In some embodiments, the sheet metal box has closed sheet metal vertical sides, a closed sheet metal bottom side and a closed sheet metal rear side.

In some embodiments, the sheet metal of the box has a thickness greater than a thickness of the wrapper of the insulated cabinet.

In some embodiments, the thickness of the sheet metal of the box is at least twice the thickness of the wrapper of the insulated cabinet.

It is intended that reference to a range of numbers disclosed herein (for example, <NUM> to <NUM>) also incorporates reference to all rational numbers within that range (for example, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>) and also any range of rational numbers within that range (for example, <NUM> to <NUM>, <NUM> to <NUM> and <NUM> to <NUM>) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.

As used herein the terms "pivotally" and "rotationally" (for example, the door is pivotally/rotationally connected/attached/coupled to a cabinet) includes both a purely rotational relative movement about an axis, as well as a combination of rotation about an axis and translation of that axis (an example of the combined rotation and translation being provided by a door connected to a cabinet by an articulated hinge).

The terms "torsionally stiff" and "torsionally weak" (and equivalents) used herein are relative terms meaning, respectively, having the ability to substantially resist twisting by a torque resulting from an applied force in an operational range normally expected to be encountered by a refrigerator cabinet, and not having the ability to substantially resist that torque.

The term cuboid is intended to mean, unless the context indicates otherwise, a <NUM>-dimensional structure such as a rectangular prism, comprising six main sides or faces (for example a rectangular cuboid or a square cuboid). One or more main sides may be open faces, for example an open framework (a space frame) or closed faces of the cuboid.

This invention may also broadly be said to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

The invention as defined by the claims consists in the foregoing and also envisages constructions of which the following gives examples only.

Preferred embodiments of the invention will be described by way of example only and with reference to the accompanying drawings, in which:.

Various embodiments will now be described with reference to the drawing Figures. Throughout the drawing Figures and specification, the same reference numerals may be used to designate the same or similar components, and redundant descriptions thereof may be omitted.

A refrigeration appliance <NUM> according to some embodiments of the present invention is illustrated in <FIG>. The refrigeration appliance comprises an insulated cabinet <NUM> with an open front face, and a door <NUM> for selectively opening and closing the front face. The overall height of the refrigeration appliance may, for example, be around <NUM> inches (around <NUM>) which is relatively tall for modern refrigeration appliances. The door <NUM> is openably operatively connected (such as via a rotational or pivotal connection) to the cabinet <NUM> by hinges (such as articulated hinges, one of which is visible at the top edge of the door in <FIG>) at one side thereof to selectively close the open face of the cabinet. The door may have shelves on an inner side for supporting food or bottles. The refrigeration appliance shown in <FIG> is of the "built-in" variety and so its outer front face is part of a door panel removably and adjustably attached to the actual hinged insulated cabinet door below.

With reference to <FIG>, a mass m of the door <NUM> (and any food supported on shelves on the inner side of the door) creates a moment M at a side of a torsionally weak insulated refrigeration appliance cabinet <NUM> to which the door is pivotally/rotationally connected. The moment M forces the rectangular front open face of the refrigeration appliance cabinet (and each of the other faces) into a substantially parallelogram shape, when viewed from the front of the cabinet.

The refrigeration appliance cabinet <NUM> comprises five closed faces; the left and right sides, top, bottom and back faces. By "closed", it is meant that the side or face does not allow a user access therethrough for adding/removing articles to/from a volume enclosed by the cabinet whereas an "open" side or face allows a user access therethrough to the enclosed volume.

Cabinet <NUM> is, at least in part, be formed by folding sheet metal (such as painted steel or stainless steel) to form at least a part of the cabinet wrapper. For example, the two longer, vertical side panels/closed faces and the top panel/closed face may be formed by folding a single sheet of metal into a substantially upside-down "U"-shape and the back and bottom panels/closed faces may be attached thereto by, for example riveting or welding. According to the invention, if the five closed faces are rigidly joined (or continuous, in the case of folding to form at least some of the panels) along their coincident edges, the moment M produced by the door's weight will cause the cabinet to deflect as shown in <FIG>, with each of the edges retaining their original length. The only significant deformation is that all five closed faces of the cabinet twist. Being formed from a material such as sheet steel, each closed face is very stiff in the planar direction of the face, however each face can bend or twist out of its plane. To aid in understanding, the shape of a deformed cabinet and face resulting from moment M acting on the torsionally weak cabinet may be reproduced by holding still one of the top or bottom faces of a torsionally weak rectangular prism (such as a cardboard box) while twisting the other of the top or bottom face of the box about an axis through the top and bottom faces.

The present invention seeks to actively eliminate the twist in one face of the cabinet. Actively eliminating twist in one face of the cabinet passively prevents or obstructs all of the other cabinet faces twisting and therefore prevents the entire cabinet from deforming significantly. According to the present invention, deformation of the refrigeration appliance cabinet, and therefore door drop relative to the cabinet, is eliminated or reduced to an acceptable level by adding a torsionally rigid or stiff structure to one of the five closed faces of the cabinet. That is, a structure is added (i.e., attached, coupled, fixed or connected) to the cabinet so that the torsional rigidity/stiffness of the resulting assembly (i.e., cabinet+structure) is greater than that of the cabinet alone.

In some embodiments, the cabinet comprises an outer skin or wrapper, inner liner, and an insulating material in between. The sheet steel forming the wrapper may be for example steel sheet with a thickness of less than <NUM>, preferably between about <NUM> and <NUM>, most preferably about <NUM>. The cabinet is a torsionally weak structure, due at least in part to the relatively thin section of the sheet material. The folded corners or edges between the side and top panels present relatively rigid edges between the top and sides of the cabinet. Connections between the "U"-shaped sheet and the base and back panels are also rigid, for example by riveting or by other connecting means known in the art. The front of the cabinet comprises an open face to provide access to the inside of the cabinet via a door of the refrigeration appliance.

Torsionally weak, in relation to the cabinet, means that in response to an appropriately-directed force or moment having a magnitude within an expected operational loading range, the closed faces of the cabinet can relatively easily twist out of plane. As a result the cabinet twists and the shape of the open front face of the cabinet deforms from a rectangle to a parallelogram (when viewed from in front of the cabinet) which is no longer substantially planar. Deformation of the cabinet may prevent the door from sealing the cooling compartments within the cabinet when in a closed position.

In order to prevent the torsionally weak cabinet from twisting, a torsionally stiff structure is provided to one of the five closed faces of the cabinet. For example, a torsionally stiff structure may be provided to the top face or the bottom face of the cabinet. Alternatively, a thin torsionally stiff structure may be provided to a left or right side face, or a rearface of the cabinet. In a preferred embodiment, a torsionally stiff structure is applied to the bottom or top closed face of the cabinet since typically within a building space (e.g., in a kitchen) in which a refrigeration appliance is located there is sufficient vertical height to accept a torsionally stiff structure above or below the cabinet. The torsionally stiff structure may be an auxiliary structure, attached to the cabinet subsequent to the cabinet's construction, or it may be built into the cabinet structure during the cabinet's construction. At least a part of the torsionally stiff structure may also be formed integrally with at least part of the cabinet (for example, as a folded box formed from the same sheet of steel as one or more of the panels of the cabinet) or could be formed from components completely distinct and separate from components used in the construction of the cabinet. The torsionally stiff structure could be a combination of an auxiliary structure and an existing part (such as a side or face) of the cabinet.

A torsionally stiff structure is a structure that does not significantly twist under normal operational loading. That is, when one end or face of the structure is held firmly, the structure is able to resist rotation of an opposite end of the structure about an axis through both ends (see <FIG>). A thick solid plate may be sufficiently rigid to act as a torsionally stiff structure, for example a thick steel plate having a thickness of more than <NUM>. The torsionally stiff structure could be a continuous, solid thick plate or could be a frame (e.g. a <NUM>-dimensional frame like a picture frame) cut from a solid thick plate. However, a thick plate or frame may be less preferred as it may provide a thermal heat flow path to the inside of the refrigeration appliance (if used on the inside of the wrapper such that it displaces an amount of insulation) and is an inefficient use of material.

Exemplary torsionally stiff structures that are efficient in their material usage are illustrated in <FIG>. In some embodiments, the torsionally stiff structure comprises a <NUM>-dimensional framework. In some embodiments, the torsionally stiff structure comprises a hollow cuboid or rectangular prism, e.g. a cuboid framework or a hollow cuboid with one or more closed faces.

<FIG> illustrates a torsionally stiff structure comprising a cuboid space frame <NUM>, the space frame <NUM> comprising a rigid member or strut <NUM> along or forming each edge of the frame and rigid diagonal members <NUM> across each open face or side of the space frame between diagonally opposed corners. The diagonal members <NUM> may be oppositely arranged in opposing sides of the framework <NUM>. In some embodiments, each side of the space frame may comprise a diagonal member between adjacent perimeter edge members. In some embodiments the space frame <NUM> may comprise a diagonal member across five sides of the framework, and with a single side without a diagonal memberto be attached to a closed side of the cabinet. In some embodiments the space frame may be without diagonal members, for example in a welded construction comprising edge members <NUM> that provide sufficient corner rigidity without diagonal members.

<FIG> illustrates a torsionally stiff structure comprising a sheet metal box <NUM> or cuboid. All six main sides <NUM> of the box comprise sheet metal, e.g. a sheet metal panel such as sheet steel. The thickness of the sheet metal-forming closed faces of the box is sufficiently thick to prevent twisting of the box. For example, where the thickness of the outer skin of the torsionally weak cabinet is about <NUM>, the thickness of the sheet metal box formed from the same material (such as sheet steel) as the cabinet and providing a torsionally stiff structure may be between about <NUM> to about <NUM>. The thickness of the sheet metal forming the box may, purely as an example, be at least about <NUM> times the thickness of the outer skin of the refrigeration appliance cabinet. Some faces could be thinner than others.

<FIG> illustrates a torsionally stiff structure comprising a box or cuboid <NUM> having five sheet metal, closed faces <NUM> and a sixth face or side <NUM> (the front side in the drawing figure) comprising a framework. The framework comprises four rigid perimeter or edge members <NUM> and a rigid diagonal member <NUM> in the plane of the open face to stiffen the open face. Other combinations which are not comprised by the invention of closed and open faces may be provided, for example a structure comprising four sheet metal, closed faces <NUM> and two opposed, open framework faces <NUM>, each framework face comprising four rigid perimeter members <NUM> and one or more rigid diagonal member(s) <NUM> for stiffening an open face or faces, for example as described with reference to <FIG>. As an alternative to diagonal stiffening members, open faces could be stiffened by corner gussets, for example.

<FIG> illustrates a box or cuboid <NUM> comprising five sheet metal closed faces <NUM> and a sixth, open face <NUM>. A closed face of the torsionally weak cabinet closes or provides the sixth face of the torsionally stiff structure.

In some embodiments the torsionally stiff structure comprises a cuboid sized to accommodate components of a refrigeration system of the refrigeration appliance, for example a compressor and condenser with pipework connecting to at least one evaporator for cooling at least one compartment within the cabinet. For example, the structures illustrated in <FIG> may be formed to encompass a sufficiently large volume to beneficially accommodate such a refrigeration system, in addition to preventing or reducing twisting of the cabinet.

<FIG> show two embodiments each comprising a torsionally weak cabinet <NUM> and a torsionally stiff structure <NUM> located at and rigidly secured to a base or bottom side of the torsionally weak cabinet <NUM>. The illustrated cabinet <NUM> may be the outer skin for an insulated cabinet comprising the outer skin, an inner liner and insulation between the outer skin and inner liner, the cabinet having five closed faces and an open front face. The torsionally stiff structures <NUM> in <FIG> are each sized to house components of a refrigeration system for the refrigeration appliance. As the torsionally stiff structure is located at the bottom of the cabinet the torsionally stiff structure beneficially acts as a plinth for the cabinet to house refrigeration components below the cabinet and raise the cabinet (and its enclosed compartments) slightly to ease access by a user.

In each of <FIG> the torsionally stiff structure <NUM> includes a cuboid or box <NUM>. The box <NUM> shown together with the cabinet <NUM> in <FIG> is shown separated from the cabinet <NUM> in <FIG>. The box <NUM> comprises four main closed faces; left and right faces <NUM>, a bottom face <NUM> and a rear face <NUM>. A front side is open and the box is stiffened by corner gussets <NUM>, <NUM> provided at or near to the open front face of the box <NUM>. The open front face allows for access to the refrigeration system components, for example for maintenance and/or for air flow. The open front face may be covered by a grill or grate, e.g. grate <NUM> shown in <FIG>. The door <NUM> (or at least the outer panel attached to the actual door) of the refrigeration appliance may cover the front face of the box <NUM> when in a closed position, as shown in <FIG>. Each gusset is attached to two adjacent sides of the box, or to a side of the box and a face of the cabinet <NUM>. For example, in the figures each gusset <NUM> is attached to a vertical side <NUM> and a horizontal side <NUM> of the structure while each gusset <NUM> is attached to a vertical side <NUM> and the base panel <NUM> of the cabinet <NUM>. In <FIG> and <FIG> the box <NUM> is stiffened by four gussets <NUM>, <NUM>. Two gussets <NUM> are attached to a vertical side <NUM> and to the bottom side <NUM> of the box, and two gussets <NUM> attached to vertical side <NUM> and bottom face <NUM> of the cabinet <NUM>, the four gussets <NUM>, <NUM> positioned at each corner of the open face so that a considerable central opening remains in that face. In <FIG> and <FIG>, the box is stiffened by two gussets <NUM>, each attached to a vertical side <NUM> of the box and the bottom <NUM> of the box <NUM>.

The gussets may be formed from the same sheet steel material (and thickness) as the material used to form box <NUM>. In some embodiment two gussets or four gussets may be integrally formed, e.g. cut and/or folded to form a monolithic component from a single blank or sheet material. The gussets may be substantially planar and attachment to a panel may be via a flange formed on that panel, perpendicular to the panel, such as gusset <NUM>. Alternatively, the gussets could be formed with a perpendicular flange at an edge or edges thereof adapted to be fastened directly to the face of an adjacent panel, such as gusset <NUM>.

In <FIG>, <FIG> and <FIG>, <FIG>, the top side of the box <NUM> is open. The open top side of the box is closed by attaching the box to the base or closed bottom face <NUM> of the cabinet <NUM>, for example as explained above with reference to <FIG>. The box <NUM> is rigidly fixed to the bottom side <NUM> of the cabinet. Thus in <FIG>, the bottom panel <NUM> of the cabinet closes the top side of the box <NUM> to create a torsionally stiff structure <NUM> comprising five closed main sides (the top <NUM>, bottom <NUM>, rear <NUM> and left and right sides <NUM>) and an open front with two or four gussets at the open front. <FIG> show the torsionally stiff structure <NUM> comprising the box <NUM> and the bottom panel <NUM> of the cabinet cut away from the vertical sides <NUM> of the cabinet <NUM>. In use, the cabinet bottom <NUM>, which is also the top side of the torsionally rigid structure <NUM>, is prevented from twisting because it is an integral part of a torsionally stiff assembly comprising the other five sides of the box <NUM>, which thereby prevents the entire cabinet <NUM> from twisting.

It will be appreciated that the box <NUM> itself, having an open top face, is not substantially torsionally stiff, but when rigidly fixed to base <NUM> the torsionally stiff structure <NUM> results. Alternatively, the box could also include a closed upper face, thereby increasing the torsional stiffness of the box and making the box itself torsionally stiff. The closed upper face of the torsionally stiff box could then be rigidly fixed to the cabinet bottom face <NUM> to produce a refrigeration cabinet assembly having a torsional stiffness greater than the torsional stiffness of the cabinet on its own.

The cabinet must be reliably and strongly attached to the torsionally stiff structure without allowing relative movement or flexing therebetween, otherwise the cabinet will be able to twist. In some embodiments the torsionally stiff structure or box is rigidly fixed to the outer skin of the cabinet by welding, riveting, screws or other suitable fasteners, or by any other rigid fixing means know in the art that will substantially avoid any relative sliding movement between adjacent faces of the cabinet and torsionally stiff structure.

The left and right sides <NUM>, bottom <NUM> and rear <NUM> sides of box <NUM> may be folded from sheet metal, or may be separate panels fixed together, or any combination of folding and fixing. The thickness of the sheet metal may be thicker than the thickness of the outer skin of the cabinet. The gussets may be formed from sheet metal and may have the same thickness as the metal forming the closed sides of the box or may be formed from an alternative material having adequate stiffness.

The present invention utilises a torsionally stiff structure fixed to or comprising one face of the refrigeration appliance cabinet to allow cost to be removed from the cabinet (auxiliary structural components in the cabinet such as reinforcing steel around the door opening are not required) which also improves the thermal insulation of the cabinet (by enabling insulating foam to replace the volume previously occupied by the removed heat-conducting structural components), and reduces material usage.

Claim 1:
A refrigeration appliance (<NUM>) comprising:
an assembly comprising an insulated cabinet (<NUM>) comprising five closed faces and an open face providing access to an interior of the cabinet,
a refrigeration system, and
a door (<NUM>) operatively rotationally connected to the insulated cabinet (<NUM>) to selectively open or close the open face of the insulated cabinet,
wherein the insulated cabinet comprises a wrapper formed from sheet metal, the cabinet at least in part being formed by folding sheet metal to form at least part of the wrapper, the five closed faces being rigidly joined, or continuous, in the case of folding, along their coincident edges to form at least part of the wrapper,
characterised in that
the assembly also includes a torsionally stiff structure (<NUM>) comprising a sheet metal box (<NUM>) that accommodates the refrigeration system or refrigeration system components, for example, at least a compressor, fixed to or comprising a closed bottom face or a closed top face of the wrapper, and
the torsionally stiff structure stopping or restraining the closed cabinet face to which it is attached, or which it includes, from twisting and thereby substantially increasing torsional stiffness of the assembly beyond that of the insulated cabinet alone so that the insulated cabinet has an increased ability to resist twisting.