BACKGROUND

Various appliances are available for cooking or otherwise heating food. An oven, for example, is often used for cooking food at lower to moderate temperatures for fairly long periods of time. A microwave oven, on the other hand, utilizes microwave energy and can heat at least some foods more rapidly. Toasters and toaster ovens may suffer from certain drawbacks, such as slow cooking times and/or poor cooked food quality.

SUMMARY

In general terms, this disclosure is directed to a heating assembly for a cooking appliance, such as a toaster or oven. In some embodiments, and by non-limiting example, the heating assembly includes a heating element and/or support that has a curved shape and provides infrared radiation to a cooking cavity. The infrared radiation may provide faster cooking times and improved results.

In one embodiment, a cooking appliance includes a housing defining a cooking cavity for receiving food therein. A heating assembly may be arranged to provide infrared radiation into the cooking cavity and may include a support and an electrical resistance heating element coupled to the support. For example, the heating element may include a metal material that emits infrared and other electromagnetic radiation when electrical current is passed through the metal material. The heating element may be exposed to the cooking cavity, meaning that there is no other component between all or most portions of the heating element and the cooking cavity. For example, infrared radiation emitted by the heating element may travel directly from the heating element to the cooking cavity without passing through a guard, screen, filter, protective cover or other component. In the case of a heating element including a metal material, infrared radiation may be emitted from the metal material and travel directly to the cooking cavity without passing through any other portion of the cooking appliance.

In some embodiments, the heating element has a curved shape with a concave side facing towards the cooking cavity. For example, the heating element may define a sheet having a length and a width, and a plurality of openings are formed in the sheet. The sheet may have first and second opposed sides, and the heating element may be curved so that the first side of the sheet defines the concave side and faces the cooking cavity. As an example, the sheet may define a cylindrical shell-type or other curved shape with a concave side facing the cooking cavity. In some cases, the heating assembly includes a plurality of heating elements, and each of the plurality of heating elements may have an approximately equal curved shape, or may have different curved shapes. The heating element may be flexible, e.g., so a sheet defined by the heating element can be selectively bent into a curved shape. The heating element may be resilient, e.g., so that the element returns to a flat planar shape when a stress used to bend the element into a curved shape is released. Alternately, the heating element may be plastically deformed to take a curved shape, e.g., an initially planar heating element may be deformed into a curved shape that is maintained when the bending force is released. The heating element may be out of contact with the support at portions along the length of the sheet, e.g., at portions between longitudinal ends of the sheet. Thus, the heating element (or plurality of elements) may only contact the support in a few areas along a length of the heating element. This may help prevent heat loss of the heating element to the support, allowing the element to more effectively emit infrared radiation.

In some embodiments, a retainer may be positioned between the heating element(s) and the cooking cavity with the retainer extending over and contacting a part of the heating element(s). The retainer may help properly position the heating element(s) with respect to the support, e.g., holding the heating element(s) close to the support without contacting the support. The heating element(s) may be movable relative to the retainer, e.g., to allow the heating element(s) to thermally expand and contract and move relative to the support and retainer. In some cases, the retainer may cause the heating element(s) to take the curved shape. For example, the heating element(s) may be coupled to the support using a retainer (at least in part) with the heating element(s) and the support initially in a flat or planar configuration. The support may be bent to take a curved shape, and bending of the support may cause the heating element(s) to take a curved shape as well. For example, the retainer may hold the heating element(s) relative to the support so that the heating element(s) must move with the support as it is bent.

As noted above, in some embodiments the support has a curved shape with a concave side facing the cooking cavity, e.g., the curved shape may be similar to a curved shape of the heating element(s). In some cases, the support is configured to reflect infrared radiation emitted by the heating element in a direction toward the cooking cavity, and a curved shape may help the support direct radiation in a focused or otherwise directed way toward the cooking cavity. The support may be formed of a flexible sheet of material, and the heating element may be coupled to the support such that bending of the support forms the curved shape of the heating element. A coefficient of thermal expansion of the support may be less than a coefficient of thermal expansion of the heating element, e.g., the support and heating element may expand or contract at different rates for a same change in temperature. The heating element may be slidably coupled to the support, e.g., so the heating element can move relative to the support in directions along a surface of the support. For example, the heating element may have an elongated shape having a length, and the heating element may be fixed to the support at one end and free to move relative to the support along the length of the heating element due to thermal expansion and contraction.

The heating assembly may be mounted in the cooking appliance in various ways. For example, the appliance may have a chassis that defines the-cooking cavity and is disposed at least partially within the housing. The heating assembly may be supported in at least three different locations by the chassis, e.g., at a top wall, a bottom wall, and at least one side wall of the chassis. The top and bottom wall may apply a compressive force on the support that holds the support in a bent or curved shape, and the side wall may help the support maintain or assume a desired curvature. For example, the heating assembly may be supported at the at least one side wall by a clip that at least partially defines the curved shape of the heating element. The clip may not contact the heating element, e.g., may only contact the support, yet still help define the curved shape of the heating element by helping define the curved shape of the support. In some embodiments, an air gap is formed at least partially between the housing and the chassis, e.g., so that heat generated by the heating assembly in the chassis can be vented or prevented from being conducted to the housing.

In one embodiment, a heating assembly for a cooking appliance includes a support and an electrical resistance heating element defining a sheet having a length and a width and a plurality of openings formed in the sheet. The support may provide physical support to the heating element, or perform other functions such as reflecting infrared radiation emitted by the heating element in a direction toward the heating element. The heating element, or a plurality of such elements, may be slidably coupled to the support such that the heating element is movable relative to the support along the length of the heating element. Such coupling of the heating element(s) to the support may allow movement relative to the support, e.g., if the heating element thermally expands or contracts, or if the support is bent or otherwise manipulated. For example, the support may be bent to take a curved shape with a concave side at the side where the heating element is mounted to the support. Such bending of the support may put stress on the heating element if the heating element is unable to move relative to the support. However, by coupling the heating element so as to be slidably movable relative to the support, the support may be bent from a flat, planar shape to a curved shape without placing stress on the heating element in directions parallel to the plane of the heating element sheet. Thus, bending of the support may cause the heating element to bend as well to take a curved shape similar to that of the support, but the heating element may slide or otherwise move relative to the support in one or more directions along the surface of the support and/or parallel to the heating element sheet so that heating element is not stressed or deformed along its length or width. Thus, in some cases, the support may include a flexible sheet of material, and the heating element(s) and support may be configured to bend such that the support and the heating element(s) each have a curved shape.

In some embodiments, a retainer may be coupled over the heating element(s) and to the support such that the heating element is positioned between the support and the retainer. The heating element may be slidable along its length relative to the retainer, but the retainer may limit movement of the heating element in directions away from the support, e.g., perpendicular to the surface of the support and/or the sheet of the heating element. As a result, the retainer may cause the heating element(s) to be bent or curved with bending of the support, but allow the heating element(s) to slidably move relative to the support in directions along the surface of the support and/or of the heating element sheet. For example, the support may have a first side to which the heating element(s) and the retainer are coupled, and the support, heating element(s) and retainer may be configured such that bending of the support causes the support and the heating element(s) to have a curved shape with a concave side at the first side of the support. In some cases, the heating element(s) may have first and second opposed sides and the second side of the heating element(s) may be positioned nearer to the support than the first side. However, the heating element may contact the support in only one or more locations, e.g., the second side may be out of contact with the support at portions along the length of the heating element. This may help prevent heat loss from the heating element to the support by conduction. One or more retainers may extend over a part of the heating element(s), e.g., to restrain movement away from the support, but still allow the heating element(s) to largely avoid contact with the support. In some cases, a retainer may include a space that is positioned between the heating element and the support to maintain a separation distance between the heating element and the support. The retainer may be positioned over a part of the heating element(s) at a location between opposite ends of the heating elements, e.g., at a point midway along the length of the heating element(s).

In one embodiment, a method of assembling a cooking appliance includes providing a chassis that defines at least one cooking cavity for receiving food therein, where the chassis includes a top wall, a bottom wall, and at least one side wall. At least one heating assembly, e.g., including a support and a heating element attached to the support, may be inserted at least partially within the chassis. Prior to inserting the at least one heating assembly, the support is substantially flat, but is formed into a curved shaped and held within the chassis. A concave side of the heating assembly created by forming the heating assembly into a curved shape may face towards the at least one cooking cavity.

In one embodiment, a cooking appliance includes a housing defining a cooking cavity for receiving food therein, and a heating assembly arranged to provide infrared radiation into the cooking cavity. The heating assembly may include a support having a curved shape with a concave side facing toward the cooking cavity, and an electrical resistance heating element coupled to the support and exposed to the cooking cavity. The heating element may be curved, or not, e.g., have a flat, planar configuration. The support may be configured to have a planar shape when in an unstressed state and to have the curved shape when in a stressed state. For example, the support may include a sheet of flexible material that is flat and planar when unstressed and can be stressed, e.g., by bending, to take a curved shape. The support may be mounted in the cooking appliance in the stressed state such that the support maintains its curved shape with the concave side facing towards the cooking cavity even with thermal expansion and thermal contraction of the support. Thus, if the support elongates or contracts in one or more dimensions due to heating or cooling of the support, the support may remain in a stressed state and maintain a curved shape.

In one embodiment, one or more heating elements attached to the support may each define a sheet having a length and a width and having a plurality of openings formed in the sheet. As noted above, the support may include a flexible sheet of material, and the heating element and support may be configured to bend such that the support and the heating element each have the curved shape. For example, bending of the support may also cause bending of the attached heating element(s) to take a curved shape. A retainer may be coupled over the heating element and to the support such that the heating element is positioned between the support and the retainer. The heating element may be slidable along its length relative to the retainer and the support, and the heating element may be out of contact with the support at portions along its length. Each of the one or more heating elements may have first and second opposed sides with the second side positioned nearer to the support than the first side. The second side of the heating element(s) may be out of contact with the support at portions along the length of the heating elements, e.g., to reduce heat loss by conduction to the support. The retainer may be positioned over the part of the heating element(s) at a location between opposite longitudinal ends of the heating element(s). In some cases, the retainer may include a spacer between the heating element and support to keep the heating element out of contact with the support. The support may be configured to reflect infrared radiation emitted by the heating element in a direction toward the heating element, e.g., to help heat the heating element more rapidly to allow emission of infrared radiation.

A variety of additional aspects will be set forth in the description that follows. The aspects can relate to individual features and to combination of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based.

