Patent Description:
Heat is generated by the magnetron and other components of a microwave oven. To cool these components, the oven draws in cool air and blows that air over the components. The oven then blows that same air through the oven cavity to carry away heat and smells produced within the oven cavity. This airflow also allows for condensation to be carried away and out of the oven. <CIT> discloses an oven comprising a cavity ventilation system and a heating element according to the preamble of claim <NUM>. <CIT> discloses an oven comprising a heating element positioned at the top of the cavity. <CIT> discloses an oven comprising a heating element and a cooking convection fan positioned at the top of the cavity. <CIT> discloses an oven comprising a cavity ventilation system and a heating element positioned at the top of the cavity.

A microwave oven draws in cool air from a vent, blows that air over the magnetron and other components of the microwave to cool them, and performs cavity ventilation using this same air to carry away heat, smells, and condensation produced within the oven cavity. This cavity ventilation may be achieved by providing this airflow to a duct extending into the oven cavity, where the airflow passes through the cavity and then out through a cavity outlet. The duct may be positioned within the cavity to provide the heated airflow along an inner glass surface of the microwave door (e.g., to the door glass facing the cavity side). This airflow along the inner surface of the microwave door is designed to keep the door free from condensation. The cavity outlet may be positioned to the rear of the oven cavity to allow the airflow to pass across the cavity before exiting.

Some microwaves include a heating element mounted to the ceiling of the oven cavity. These ovens may use the heating element to heat the air within the oven cavity, resulting in food that is cooked-through and crispy. This, combined with the microwave cooking, is called combination cooking, and produces quickly and evenly cooked food. Ovens providing for both microware and conventional cooking are sometimes referred to as combi-ovens.

As the combi-oven heating element is exposed within the cavity, it may be possible for an operator of the oven to accidentally touch the element when removing cooked items from the oven cavity. To avoid such occurrences, the duct may be extended into the oven cavity below and in front of the heating element disposed at the top of the oven cavity. Advantageously, a hand protection feature may be formed by a portion of the same air duct used for removing door condensation. This allows the air duct to perform both condensation management while the oven is being used as well as hand protection from the heating element when the door of the oven is opened.

In one or more illustrative embodiments, a hand protecting cavity ventilation system for an oven is provided. The system includes an air duct, positioned at a top of a cavity of the oven, the air duct having a duct outlet aimed towards a door to the cavity to provide an airflow along an inner surface of the door. The air duct extends downward from the ceiling of the cavity in front of and below a heating element disposed below the ceiling of the cavity. The air duct forms a vertically displaced hand protection portion to act as a barrier in front of the heating element, thereby guarding the heating element when the door of the oven is opened.

In one or more illustrative embodiments, the duct outlet defines one or more openings on a lateral surface of the duct outlet to direct the airflow downward toward the door of the oven.

In one or more illustrative embodiments, the one or more openings include an array of equally-sized holes.

In one or more illustrative embodiments, the one or more openings include an array of equally-spaced holes.

In one or more illustrative embodiments, the air duct increases in cross-sectional area in a direction of the airflow toward the duct outlet.

In one or more illustrative embodiments, the heating element is mounted a first distance below the ceiling of the cavity, the air duct is mounted a second distance below the ceiling of the cavity, and the second distance is greater than the first distance to achieve a hand protection function.

In one or more illustrative embodiments, a front surface of the air duct curves upward from the duct outlet to form a front of the hand protection portion.

In one or more illustrative embodiments, the inner surface of the door is a glass surface.

In one or more illustrative embodiments, the duct outlet is integral with the top ceiling of the cavity.

In one or more illustrative embodiments, the duct outlet is formed of one or more of stainless steel or ceramic enamel.

In one or more illustrative embodiments, the oven is a microwave oven and the airflow is heated by passage over a magnetron of the oven.

In one or more illustrative embodiments, the heating element is disposed at a top of the cavity of the oven.

In one or more illustrative embodiments, the cavity defines an opening on a front face, the door is operable to move between an opened position allowing access to the cavity and a closed position sealing the cavity, and the air duct acts as a barrier in front of the heating element, thereby guarding the heating element when the door of the oven is in the opened position.

In one or more illustrative embodiments, the system further includes a ventilation plane including oven electronics, wherein the air duct defines a duct inlet to receive air from the ventilation plane.

In one or more illustrative embodiments, , the system further includes a valve, located in the ventilation plane, configured to allow for a selective separation of a portion of airflow over the oven electronics to be provided into the cavity, such that when the valve is in an open position, the portion of airflow is separated out and directed into the air duct underneath the ventilation plane and into the cavity, and when the valve is in a closed position, the portion of airflow is disengaged and the air duct underneath the ventilation plane is bypassed.

Referring collectively to <FIG>, a combi-oven <NUM> including a condensation-managing hand protection feature is depicted. In general, the oven <NUM> cooks food placed into an oven cavity <NUM> by exposing the food to electromagnetic radiation in the microwave frequency range. This radiation is produced by a magnetron, where electrons are emitted from a hot cathode to resonant cavities of the anode at speeds that generate the microwave energy. The oven cavity <NUM> may have an access opening and walls at the top, left side, right side, back and bottom. A door <NUM> may be arranged at a front of the oven cavity <NUM>. The door <NUM> operate to move between an open position where the oven cavity <NUM> is accessible and a closed position where the door <NUM> seals the opening. To perform a cooking cycle, the food is placed in the oven cavity <NUM>, the door <NUM> is closed, and the magnetron is activated. During operation, microwave energy travels from the magnetron through a waveguide and is distributed into the oven cavity <NUM>. This energy transfers to the food via dielectric heating. The oven cavity <NUM> may be made of a material such as stainless steel or ceramic enamel, to prevent the passage of the radiation outside of the oven cavity <NUM>. The door <NUM> may include a clear window for observing the food, shielded by a metal mesh to prevent the passage of the radiation. Once the food is heated, the magnetron is deactivated, the door <NUM> is reopened, and the food is removed. The oven <NUM> may also include a door switch (not shown) that detects whether the door <NUM> is open or closed, such that the magnetron is automatically deactivated should the door <NUM> be opened during a cooking cycle.

The magnetron and other components of the oven <NUM> produce waste heat when generating the microwave energy. Accordingly, the oven <NUM> includes an air duct <NUM> underneath a ventilation plane <NUM> of the oven <NUM> to draw this heat away. The ventilation plane <NUM> refers to the portion of the oven <NUM> including the magnetron and other components to be cooled. The air duct <NUM> provides an airflow channel that extends horizontally above the oven cavity <NUM> to connect the ventilation plane <NUM> with the forward section of the oven cavity <NUM>. A duct inlet section <NUM> of the air duct <NUM> receives an airflow from the ventilation plane <NUM>, while a duct outlet section <NUM> of the air duct <NUM> provides the airflow into the oven cavity <NUM>. In some examples, to improve the flow of air, the air duct <NUM> increases in cross-sectional area in a direction of the airflow toward the duct outlet section <NUM>.

The duct outlet section <NUM> of the air duct <NUM> defines a pattern of openings <NUM> placed on the lateral surface of the oven cavity <NUM>. As shown in the illustrated example, the one or more openings <NUM> include an array of equally-sized, equally-spaced openings <NUM> (e.g., two rows of openings <NUM> across the lateral surface). It should be noted that this is merely an example arrangement of openings <NUM>, and other possibilities are contemplated. In some other examples, the openings <NUM> may include irregularly-spaced or differently-sized openings, and/or one or more slots that run along the length or width of the duct outlet section <NUM>. Regardless of layout, the airflow entering from the air duct <NUM> is provided to the oven cavity <NUM>, where the airflow then circulates in the oven cavity <NUM> and is exhausted from the oven cavity <NUM> through an oven outlet section <NUM>. The oven outlet section <NUM> may include an arrangement of cavity openings <NUM> through which the airflow exits the oven cavity <NUM>, e.g., to pass into an exhaust vent away from the oven <NUM> or into a filter for recirculation into a room in which the oven <NUM> is placed.

Because the oven <NUM> operates by heating water molecules, the cooking process tends to generate steam. This steam may condense on the cooler inside surfaces of the oven cavity <NUM>. This condensation may be more prevalent when cooking foods of high moisture content for extended periods of time. In these instances, the condensation may be especially noticeable to the user. In addition to cooling the magnetron, the airflow exiting from the ventilation plane <NUM> into the oven cavity <NUM> is hot and dry, and may advantageously be used to carry away the condensation, as well as providing an airflow circulation into the oven cavity <NUM> (e.g., for condensation management, odor reduction, heat management, etc.).

The duct outlet section <NUM> of the air duct <NUM> may be located in close proximity to an inner glass surface of the door <NUM>, to aid in removing water condensation from that inner surface. The lateral surface of the duct outlet section <NUM> may extend across the entire front lateral area of the door <NUM> as shown in <FIG>. Additionally or alternatively, the lateral surface of the duct outlet section <NUM> may extend only partially across the area of the door <NUM>.

The described airflow may not always be necessary. In an example, use of the airflow may depend on the particular cooking function that is selected. In another example, use of the airflow may depend on how much humidity is sensed as being present in the oven cavity <NUM>. In yet another example, the airflow may depend on whether predefined temperature set points within the oven cavity <NUM> have been reached. Based on these or other factors, the airflow through the oven cavity <NUM> may be regulated by operation of a valve <NUM> located in the ventilation plane <NUM> in correspondence with the duct inlet section <NUM> to the air duct <NUM>. The valve <NUM> may allow for the selective separation of a portion of the main cooling flow of the magnetron and other oven electronics to be provided into the oven cavity <NUM>.

The valve <NUM> can be selectively regulated into at least two positions: an open position and a closed position. When the valve <NUM> is in open position, shown as open valve 9a in <FIG>, a portion of the cooling system airflow is separated out and directed into the air duct <NUM> underneath the ventilation plane <NUM> and then into the oven cavity <NUM>. When the valve <NUM> is in closed position, as illustrated as closed valve 9b in <FIG>, this spillage effect is disengaged and the air duct <NUM> underneath the ventilation plane <NUM> is bypassed. Accordingly, in the closed position, no ventilation of the oven cavity <NUM> is performed.

The valve <NUM> may be regulated by a dedicated actuator <NUM>, which may be used to control positioning of the valve <NUM> between the open position and the closed position. In a preferable embodiment, the valve <NUM> may have the two positions (open and closed) as shown in <FIG>. However, it is possible that in other examples the positioning of the valve <NUM> may additionally or alternately be controllable into one or more intermediate positions, between the open position and the closed position, to allow for the regulation of how much airflow is to be provided into the oven cavity <NUM>.

The oven <NUM> may also include a heating element <NUM> to provide for baking. The heating element <NUM> may be a resistive heating element configured to heat the air of the oven cavity <NUM>, either alone or in combination with the microwave energy provided via the magnetron. As shown, the heating element <NUM> may generally be mounted below a top surface or ceiling <NUM> of the oven cavity <NUM>. Use of the heating element <NUM>, combined with the operation of the magnetron, may aid in the quick and even cooking of food.

The heating element <NUM> tends to remain hot after a cooking cycle of the oven <NUM> is completed. As the heating element <NUM> is exposed within the oven cavity <NUM>, it may be possible for an operator of the oven <NUM> to accidentally touch the still-hot heating element <NUM> when removing heated items from the oven cavity <NUM>. To protect the operator, the air duct <NUM> may form a hand protection portion <NUM> at the duct outlet section <NUM>. The hand protection portion <NUM> of the air duct <NUM> may extend from the top ceiling <NUM> of the oven cavity <NUM> in front of the heating element <NUM> to prevent accidental operator contact with the heating element <NUM>. As shown, the duct outlet protrudes from the top of the oven cavity <NUM> in front of the heating element <NUM>, and extends to a position below the heating element <NUM> near a door <NUM> of the oven <NUM>, to achieve a dual function of conveying airflow in a downward direction and also providing hand protection for the heating element <NUM>.

As shown, a front surface of the hand protection portion <NUM> of the duct outlet section <NUM> may be rounded, e.g., as a fillet, to curve downward from the front ceiling of the oven cavity <NUM> to form a front portion of the hand protection portion <NUM>. The hand protection portion <NUM> may further define a lateral surface extending rearward toward the back of the oven cavity <NUM>, leading to a sloped surface extending rearward and upward toward the ceiling of the oven cavity <NUM>. In some examples, the heating element <NUM> is mounted a first distance below the top ceiling <NUM> of the oven cavity <NUM>, and the duct outlet section <NUM> of the air duct <NUM> is mounted a second distance below the top ceiling <NUM> of the oven cavity <NUM>, where the second distance is greater than the first distance.

The hand protection portion <NUM> of the duct outlet section <NUM> may be integral with the ceiling <NUM> of the oven cavity <NUM>. For instance, the hand protection portion <NUM> may be molded as part of the oven cavity <NUM> itself. In such a case, the duct outlet section <NUM> may be formed of the same material as the oven cavity <NUM> itself, such as stainless steel or ceramic enamel. In other examples, the hand protection portion <NUM> of the duct outlet section <NUM> may be a separate element. In such a case, the hand protection portion <NUM> may be formed of a material the same as that of the oven cavity <NUM> and/or of another material, such as a metal or ceramic capable of withstanding the heat present within the oven cavity <NUM> in proximity to the heating element <NUM>.

The duct outlet section <NUM> of the air duct <NUM> may be provided on the lateral surface of the hand protection portion <NUM>. In doing so, the pattern of openings <NUM> of the duct outlet section <NUM> of the air duct <NUM> may therefore be embedded within the hand protection portion <NUM> itself. Accordingly, the hand protection portion <NUM> affords both protection from accidental contact with the heating element <NUM> and the providing of airflow from duct outlet section <NUM> into the oven cavity <NUM>. Moreover, the protrusion of the hand protection portion <NUM> into the oven cavity <NUM>, as compared to the duct outlet section <NUM> of the air duct <NUM> being flush with the ceiling of the oven cavity <NUM>, allows for the airflow from the duct outlet section <NUM> of the air duct <NUM> to be better addressed towards the glass inner surface of the door <NUM>.

Thus, the air duct <NUM> for removing oven condensation may be provided that extends below the heating element <NUM> disposed at the top of the oven cavity <NUM>. As the hand protection portion <NUM> extends downward from the ceiling of the oven cavity <NUM> in front of and below the heating element <NUM>, the air duct <NUM> also acts as the hand protection portion <NUM> when the door <NUM> of the oven <NUM> is opened. This allows the air duct <NUM> to perform both condensation management and hand protection functions.

All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as "a," "the," "said," etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.

Claim 1:
An oven (<NUM>) including a hand protecting cavity ventilation system comprising:
an air duct (<NUM>), positioned at a top of a cavity (<NUM>) of the oven (<NUM>), the air duct (<NUM>) having a duct outlet (<NUM>) aimed towards a door (<NUM>) to the cavity (<NUM>) to provide an airflow along an inner surface of the door (<NUM>),
the air duct (<NUM>) extending downward from a ceiling (<NUM>) of the cavity (<NUM>) in front of and below a heating element (<NUM>) disposed below the ceiling (<NUM>) of the cavity (<NUM>),
characterized in that the air duct (<NUM>) forms a vertically displaced hand protection portion (<NUM>) to act as a barrier in front of the heating element (<NUM>), thereby guarding the heating element (<NUM>) when the door (<NUM>) of the oven (<NUM>) is opened.