Example embodiments generally relate to ovens and, more particularly, relate to an oven that uses radio frequency (RF) heating along with convection heating and an RF choke for use with the same.
Combination ovens that are capable of cooking using more than one heating source (e.g., convection, steam, microwave, etc.) have been in use for decades. Each cooking source comes with its own distinct set of characteristics. Thus, a combination oven can typically leverage the advantages of each different cooking source to attempt to provide a cooking process that is improved in terms of time and/or quality.
In some cases, microwave cooking may be faster than convection or other types of cooking. Thus, microwave cooking may be employed to speed up the cooking process. However, a microwave typically cannot be used to cook some foods and also cannot brown foods. Given that browning may add certain desirable characteristics in relation to taste and appearance, it may be necessary to employ another cooking method in addition to microwave cooking in order to achieve browning. In some cases, the application of heat for purposes of browning may involve the use of heated airflow provided within the oven cavity to deliver heat to a surface of the food product.
However, even by employing a combination of microwave and airflow, the limitations of conventional microwave cooking relative to penetration of the food product may still render the combination less than ideal. Moreover, a typical microwave is somewhat indiscriminate or uncontrollable in the way it applies energy to the food product. Thus, it may be desirable to provide further improvements to the ability of an operator to achieve a superior cooking result. However, providing an oven with improved capabilities relative to cooking food with a combination of controllable RF energy and convection energy may require the structures and operations of the oven to be substantially redesigned or reconsidered.
Some example embodiments may therefore provide improved structures and/or systems for applying heat to the food product in the oven. Moreover, such improvements may necessitate new arrangements for supporting or operating such structures or systems.
In an example embodiment, an oven is provided. The oven may include a door movable between an open position and a closed position, a cooking chamber configured to receive a food product, an RF energy source configured to apply RF energy to the food product, and an RF choke disposed at a portion of the door facing the cooking chamber when the door is in the closed position. The cooking chamber may be defined at least in part by a top wall, a bottom wall, a first sidewall and a second sidewall, the cooking chamber further defining an opening that interfaces with the door. The RF choke may include a base portion made from a metallic sheet, and a plurality of resonant elements. The base portion may be disposed in a first plane substantially parallel to a second plane in which the door lies. The resonant elements may be folded out of the first plane toward the door. The resonant elements may be formed in rows to define a top row of resonant elements, a bottom row of resonant elements, a first side row of resonant elements and a second side row of resonant elements, which are proximate to respective ones of the top wall, the bottom wall, the first sidewall and the second sidewall of the cooking chamber when the door is in the closed position. At least one of the rows may be folded out of the first plane at a different angle relative to the first plane than other ones of the rows.
In an example embodiment, an RF choke for an oven having a door movable between an open position and a closed position to interface with an opening defined in a cooking chamber of the oven is provided. The RF choke may include a base portion and a plurality of resonant elements formed in rows. The cooking chamber may be defined at least in part by a top wall, a bottom wall, a first sidewall and a second sidewall. The RF choke may be disposed at a portion of the door facing the cooking chamber when the door is in the closed position. The base portion may be a metallic sheet having peripheral edges. The base portion may be disposed in a first plane substantially parallel to a second plane in which the door lies. The resonant elements may be folded out of the first plane toward the door to define a top row of resonant elements, a bottom row of resonant elements, a first side row of resonant elements and a second side row of resonant elements, which are proximate to respective ones of the top wall, the bottom wall, the first sidewall and the second sidewall of the cooking chamber when the door is in the closed position. At least one of the rows may be folded out of the first plane at a different angle relative to the first plane than other ones of the rows.
Some example embodiments may improve the cooking performance or operator experience when cooking with an oven employing an example embodiment.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
Some example embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all example embodiments are shown. Indeed, the examples described and pictured herein should not be construed as being limiting as to the scope, applicability or configuration of the present disclosure. Rather, these example embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout. Furthermore, as used herein, the term “or” is to be interpreted as a logical operator that results in true whenever one or more of its operands are true. As used herein, operable coupling should be understood to relate to direct or indirect connection that, in either case, enables functional interconnection of components that are operably coupled to each other.
Some example embodiments may improve the cooking performance of an oven and/or may improve the operator experience of individuals employing an example embodiment. In this regard, the oven may cook food relatively quickly, based on the application of controllable RF energy, and also enable the food to be browned by providing hot air into the oven with a convection system as described herein. However, in order to increase cooking speed using RF energy, prevention of RF leakage becomes an important consideration. Meanwhile, the cleanability of the oven also remains a key component to providing a quality product. Accordingly, some example embodiments may provide an improved choke design and interface structure to achieve the goals of maintaining RF energy within the cooking chamber of the oven, while also allowing the interface between the door and the cooking chamber to be improved.
In some embodiments, the oven 100 may include multiple racks or may include rack (or pan) supports 108 or guide slots in order to facilitate the insertion of one or more racks 110 or pans holding food product that is to be cooked. In an example embodiment, air delivery orifices 112 may be positioned proximate to the rack supports 108 (e.g., just below a level of the rack supports in one embodiment) to enable heated air to be forced into the cooking chamber 102 via a heated-air circulation fan (not shown in
In an example embodiment, food product placed on a pan or one of the racks 110 (or simply on a base of the cooking chamber 102 in embodiments where racks 110 are not employed) may be heated at least partially using radio frequency (RF) energy. Meanwhile, the airflow that may be provided may be heated to enable further heating or even browning to be accomplished. Of note, a metallic pan may be placed on one of the rack supports 108 or racks 110 of some example embodiments. However, the oven 100 may be configured to employ frequencies and/or mitigation strategies for detecting and/or preventing any arcing that might otherwise be generated by using RF energy with metallic components.
In an example embodiment, the RF energy may be delivered to the cooking chamber 102 via an antenna assembly 130 disposed proximate to the cooking chamber 102. In some embodiments, multiple components may be provided in the antenna assembly 130, and the components may be placed on opposing sides of the cooking chamber 102. The antenna assembly 130 may include one or more instances of a power amplifier, a launcher, waveguide and/or the like that are configured to couple RF energy into the cooking chamber 102.
The cooking chamber 102 may be configured to provide RF shielding on five sides thereof (e.g., the top, bottom, back, and right and left sides), but the door 104 may include a choke 140 to provide RF shielding for the front side. The choke 140 may therefore be configured to fit closely with the opening defined at the front side of the cooking chamber 102 to prevent leakage of RF energy out of the cooking chamber 102 when the door 104 is shut and RF energy is being applied into the cooking chamber 102 via the antenna assembly 130.
In an example embodiment, a gasket 142 may be provided to extend around the periphery of the choke 140. In this regard, the gasket 142 may be formed from a material such as wire mesh, rubber, silicon, or other such materials that may be somewhat compressible between the door 104 and a periphery of the opening into the cooking chamber 102. The gasket 142 may, in some cases, provide a substantially air tight seal. However, in other cases (e.g., where the wire mesh is employed), the gasket 142 may allow air to pass therethrough. Particularly in cases where the gasket 142 is substantially air tight, it may be desirable to provide an air cleaning system in connection with the first air circulation system described above.
The antenna assembly 130 may be configured to generate controllable RF emissions into the cooking chamber 102 using solid state components. Thus, the oven 100 may not employ any magnetrons, but instead use only solid state components for the generation and control of the RF energy applied into the cooking chamber 102. The use of solid state components may provide distinct advantages in terms of allowing the characteristics (e.g., power/energy level, phase and frequency) of the RF energy to be controlled to a greater degree than is possible using magnetrons. However, since relatively high powers are necessary to cook food, the solid state components themselves will also generate relatively high amounts of heat, which must be removed efficiently in order to keep the solid state components cool and avoid damage thereto. To cool the solid state components, the oven 100 may include a second air circulation system.
The second air circulation system may operate within an oven body 150 of the oven 100 to circulate cooling air for preventing overheating of the solid state components that power and control the application of RF energy to the cooking chamber 102. The second air circulation system may include an inlet array 152 that is formed at a bottom (or basement) portion of the oven body 150. In particular, the basement region of the oven body 150 may be a substantially hollow cavity within the oven body 150 that is disposed below the cooking chamber 102. The inlet array 152 may include multiple inlet ports that are disposed on each opposing side of the oven body 150 (e.g., right and left sides when viewing the oven 100 from the front) proximate to the basement, and also on the front of the oven body 150 proximate to the basement. Portions of the inlet array 152 that are disposed on the sides of the oven body 150 may be formed at an angle relative to the majority portion of the oven body 150 on each respective side. In this regard, the portions of the inlet array 152 that are disposed on the sides of the oven body 150 may be tapered toward each other at an angle of about twenty degrees (e.g., between ten degrees and thirty degrees). This tapering may ensure that even when the oven 100 is inserted into a space that is sized precisely wide enough to accommodate the oven body 150 (e.g., due to walls or other equipment being adjacent to the sides of the oven body 150), a space is formed proximate to the basement to permit entry of air into the inlet array 152. At the front portion of the oven body 150 proximate to the basement, the corresponding portion of the inlet array 152 may lie in the same plane as (or at least in a parallel plane to) the front of the oven 100 when the door 104 is closed. No such tapering is required to provide a passage for air entry into the inlet array 152 in the front portion of the oven body 150 since this region must remain clear to permit opening of the door 104.
From the basement, ducting may provide a path for air that enters the basement through the inlet array 152 to move upward (under influence from a cool-air circulating fan) through the oven body 150 to an attic portion inside which control electronics (e.g., the solid state components) are located. The attic portion may include various structures for ensuring that the air passing from the basement to the attic and ultimately out of the oven body 150 via outlet louvers 154 is passed proximate to the control electronics to remove heat from the control electronics. Hot air (i.e., air that has removed heat from the control electronics) is then expelled from the outlet louvers 154. In some embodiments, outlet louvers 154 may be provided at right and left sides of the oven body 150 and at the rear of the oven body 150 proximate to the attic. Placement of the inlet array 152 at the basement and the outlet louvers 154 at the attic ensures that the normal tendency of hotter air to rise will prevent recirculation of expelled air (from the outlet louvers 154) back through the system by being drawn into the inlet array 152. As such, air drawn into the inlet array 152 can reliably be expected to be air at ambient room temperature, and not recycled, expelled cooling air.
As mentioned above, the first energy source 200 may be an RF energy source (or RF heating source) configured to generate relatively broad spectrum RF energy or a specific narrow band, phase controlled energy source to cook food product placed in the cooking chamber 102 of the oven 100. Thus, for example, the first energy source 200 may include the antenna assembly 130 and an RF generator 204. The RF generator 204 of one example embodiment may be configured to generate RF energy at selected levels and with selected frequencies and phases. In some cases, the frequencies may be selected over a range of about 6 MHz to 246 GHz. However, other RF energy bands may be employed in some cases. In some examples, frequencies may be selected from the ISM bands for application by the RF generator 204.
In some cases, the antenna assembly 130 may be configured to transmit the RF energy into the cooking chamber 102 and receive feedback to indicate absorption levels of respective different frequencies in the food product. The absorption levels may then be used to control the generation of RF energy to provide balanced cooking of the food product. Feedback indicative of absorption levels is not necessarily employed in all embodiments however. For example, some embodiments may employ algorithms for selecting frequency and phase based on pre-determined strategies identified for particular combinations of selected cook times, power levels, food types, recipes and/or the like. In some embodiments, the antenna assembly 130 may include multiple antennas, waveguides, launchers, and RF transparent coverings that provide an interface between the antenna assembly 130 and the cooking chamber 102. Thus, for example, four waveguides may be provided and, in some cases, each waveguide may receive RF energy generated by its own respective power module or power amplifier of the RF generator 204 operating under the control of control electronics 220. In an alternative embodiment, a single multiplexed generator may be employed to deliver different energy into each waveguide or to pairs of waveguides to provide energy into the cooking chamber 102.
In an example embodiment, the second energy source 210 may be an energy source capable of inducing browning and/or convective heating of the food product. Thus, for example, the second energy source 210 may a convection heating system including an airflow generator 212 and an air heater 214. The airflow generator 212 may be embodied as or include the heated-air circulation fan or another device capable of driving airflow through the cooking chamber 102 (e.g., via the air delivery orifices 112). The air heater 214 may be an electrical heating element or other type of heater that heats air to be driven toward the food product by the airflow generator 212. Both the temperature of the air and the speed of airflow will impact cooking times that are achieved using the second energy source 210, and more particularly using the combination of the first and second energy sources 200 and 210.
In an example embodiment, the first and second energy sources 200 and 210 may be controlled, either directly or indirectly, by the control electronics 220. The control electronics 220 may be configured to receive inputs descriptive of the selected recipe, food product and/or cooking conditions in order to provide instructions or controls to the first and second energy sources 200 and 210 to control the cooking process. In some embodiments, the control electronics 220 may be configured to receive static and/or dynamic inputs regarding the food product and/or cooking conditions. Dynamic inputs may include feedback data regarding phase and frequency of the RF energy applied to the cooking chamber 102. In some cases, dynamic inputs may include adjustments made by the operator during the cooking process. The static inputs may include parameters that are input by the operator as initial conditions. For example, the static inputs may include a description of the food type, initial state or temperature, final desired state or temperature, a number and/or size of portions to be cooked, a location of the item to be cooked (e.g., when multiple trays or levels are employed), a selection of a recipe (e.g., defining a series of cooking steps) and/or the like.
In some embodiments, the control electronics 220 may be configured to also provide instructions or controls to the airflow generator 212 and/or the air heater 214 to control airflow through the cooking chamber 102. However, rather than simply relying upon the control of the airflow generator 212 to impact characteristics of airflow in the cooking chamber 102, some example embodiments may further employ the first energy source 200 to also apply energy for cooking the food product so that a balance or management of the amount of energy applied by each of the sources is managed by the control electronics 220.
In an example embodiment, the control electronics 220 may be configured to access algorithms and/or data tables that define RF cooking parameters used to drive the RF generator 204 to generate RF energy at corresponding levels, phases and/or frequencies for corresponding times determined by the algorithms or data tables based on initial condition information descriptive of the food product and/or based on recipes defining sequences of cooking steps. As such, the control electronics 220 may be configured to employ RF cooking as a primary energy source for cooking the food product, while the convective heat application is a secondary energy source for browning and faster cooking. However, other energy sources (e.g., tertiary or other energy sources) may also be employed in the cooking process.
In some cases, cooking signatures, programs or recipes may be provided to define the cooking parameters to be employed for each of multiple potential cooking stages or steps that may be defined for the food product and the control electronics 220 may be configured to access and/or execute the cooking signatures, programs or recipes (all of which may generally be referred to herein as recipes). In some embodiments, the control electronics 220 may be configured to determine which recipe to execute based on inputs provided by the user except to the extent that dynamic inputs (i.e., changes to cooking parameters while a program is already being executed) are provided. In an example embodiment, an input to the control electronics 220 may also include browning instructions. In this regard, for example, the browning instructions may include instructions regarding the air speed, air temperature and/or time of application of a set air speed and temperature combination (e.g., start and stop times for certain speed and heating combinations). The browning instructions may be provided via a user interface accessible to the operator, or may be part of the cooking signatures, programs or recipes.
As discussed above, the first energy source 200 may be an RF energy source configured to generate selected RF frequencies (e.g., in the ISM band) into the cooking chamber 102. The choke 140 may be provided to seal the RF frequencies in the cooking chamber 102 during operation of the oven 100 with the door 104 closed. The choke 140 therefore operates at the interface between the cooking chamber 102 and the door 104. The interface is the relatively large opening into the front of the cooking chamber 102.
The choke 140 is provided to seal RF energy at the interface by providing what is essentially a tuned reflector assembly to keep RF energy in the cooking chamber 102. The choke 140 is constructed based on providing a quarter-wave resonant circuit. More particularly, the choke 140 employs ¼ wavelength (λ) resonant elements that have a width that is substantially uniform around the perimeter of the choke 140. The provision of these types of ¼ wavelength resonant elements is, as a general matter, relatively conventional. However, because of the nature of the shape of the cooking chamber 102, and the size and weight of the door 105, example embodiments may employ a uniquely structured design for the choke 140. Moreover, because the choke 140 has a uniquely structured design, the method of making the choke 140 may also be unique.
Before the specific structure of the choke 140 is described, the general shape of the cooking chamber 102 and unique aspects of the interface will be discussed to give a greater appreciation for the potential desire for inclusion of the unique structural design aspects mentioned above in reference to
Referring primarily to
As shown in
However, the intersections between the bottom wall 310 and both the first and second sidewalls 315 and 320 (and corresponding corners formed thereby) are different. In this regard, although the bottom wall 310 extends substantially perpendicular to the first sidewall 315, the intersection between the bottom wall 310 and the first sidewall 315 does not form a right angle along its entire length. Instead, the intersection between the bottom wall 310 and the first sidewall 315 is curved along its entire length. Similarly, although the bottom wall 310 extends substantially perpendicular to the second sidewall 320, the intersection between the bottom wall 310 and the second sidewall 320 does not form a right angle along its entire length. Instead, the intersection between the bottom wall 310 and the second sidewall 320 is also curved along its entire length. The curves of the respective interfaces between the bottom wall 310 and both the first and second sidewalls 315 and 320 are substantially symmetrical about a centerline dividing the cooking chamber 102 midway between the respective corners. The intersections between the back wall 300 and each of the first and second sidewalls 315 and 320 and the bottom wall 310 are substantially right angle intersections except at the region where the first and second sidewalls 315 and 320 meet the bottom wall 310.
Referring specifically to
Given that the cooking chamber 102 has a specific shape at the interface with the door 104 (e.g., two rounded bottom corners and two right angle top corners), the choke 140 must also have a corresponding shape. Moreover, the requirement for the door 104 to rotate between open and closed positions while putting the choke 140 in position to function properly in light of the specific shape of the interface places further design limitations on the choke 140 and may influence the most efficient and/or advantageous ways to manufacture the choke 140.
Referring to
As can be seen from
As may be appreciated from
The fabrication of the choke 140 may therefore also require care to achieve the necessary shape changes associated with making both the rounded corners, and one set of tapered resonant elements.
As shown in
The removal section 520 may be removed (at least in part) by cutting away a portion of opposing ends of the metallic sheet 500 to shorten the length of all portions of the metallic sheet 500 to a second length L2, except for tail pieces 540. The tail pieces 540 may each be on the same side of the metallic sheet 500 and maintain the length of the metallic piece 500 as the length L1 at the corresponding long edge of the metallic sheet 500. The tail pieces 540 may have a second width W2 that is determined by the length of the resonant elements 420 extending away from the base portion 410 (after folding). The removal section 520 may include at least some pre-folded resonant elements 515 proximate to the tail pieces 540 that are removed. The removal section 520 may further be defined by a curve cut to form the round corners 530 proximate to the tail pieces 540. A side of the removal section 520 opposite the tail pieces 540 may be cut to remove some portions of pre-folded resonant elements 515 to define a taper guide 550. The taper guide 550 defines an angled edge to which the row of tapered resonant elements 535 may be folded to define the taper angle of the tapered resonant elements 535.
As can be appreciated from
In some cases, in order to preserve the strength of the tail pieces 540 after folding, at least one (and in this example, two) of the resonant elements on the tail piece 540 may be formed without fully cutting a notch completely to the end of the resonant element. Instead, as shown in
In an example embodiment, an RF choke for an oven having a door movable between an open position and a closed position to interface with an opening defined in a cooking chamber of the oven is provided. The RF choke may include a base portion and a plurality of resonant elements formed in rows. The cooking chamber may be defined at least in part by a top wall, a bottom wall, a first sidewall and a second sidewall. The RF choke may be disposed at a portion of the door facing the cooking chamber when the door is in the closed position. The base portion may be a metallic sheet having peripheral edges. The base portion may be disposed in a first plane substantially parallel to a second plane in which the door lies. The resonant elements may be folded out of the first plane toward the door to define a top row of resonant elements, a bottom row of resonant elements, a first side row of resonant elements and a second side row of resonant elements, which are proximate to respective ones of the top wall, the bottom wall, the first sidewall and the second sidewall of the cooking chamber when the door is in the closed position. At least one of the rows may be folded out of the first plane at a different angle relative to the first plane than other ones of the rows.
In some embodiments, additional optional features may be included or the features described above may be modified or augmented. Each of the additional features, modification or augmentations may be practiced in combination with the features above and/or in combination with each other. Thus, some, all or none of the additional features, modification or augmentations may be utilized in some embodiments. For example, in some cases, the base portion may have a shape substantially matching a shape of the opening. In such an example, a distance between the base portion and the top wall of the cooking chamber may be larger than a distance between the base portion and each of the bottom wall and the first and second sidewalls of the cooking chamber. In an example embodiment, the top row of resonant elements may be folded out of the first plane at the different angle relative to the first plane than the bottom row of resonant elements, the first side row of resonant elements and the second side row of resonant elements. In some examples, distal ends of resonant elements in each of the top row of resonant elements, the bottom row of resonant elements, the first side row of resonant elements and the second side row of resonant elements may be substantially equidistant from respective ones of the top wall, the bottom wall, the first sidewall and the second sidewall of the cooking chamber when the door is in the closed position. In an example embodiment, an intersection between the top wall and both of the first and second sidewalls forms a right angle, and an intersection between the bottom wall and both of the first and second sidewalls forms a curved corner. In some cases, the base portion may define a substantially round corner to correspond to the curved corner at intersections between the bottom row of resonant elements and the first and second side rows of resonant elements. In an example embodiment, the base portion may define a substantially right angle corner to correspond to the right angle at intersections between the top wall and the first and second sidewalls. In some examples, a tail piece of the bottom row of resonant elements may be folded around the substantially round corner to correspond to the curved corner. In such examples, at least one resonant element on the tail piece may be formed via slots extending linearly away from the base portion, and resonant elements disposed at locations other than the tail piece may be formed via notches cut linearly away from the base portion. In an example embodiment, distal ends of resonant elements of each of the each of the top row of resonant elements, the bottom row of resonant elements, the first side row of resonant elements and the second side row of resonant elements lie in a plane of the opening.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. In cases where advantages, benefits or solutions to problems are described herein, it should be appreciated that such advantages, benefits and/or solutions may be applicable to some example embodiments, but not necessarily all example embodiments. Thus, any advantages, benefits or solutions described herein should not be thought of as being critical, required or essential to all embodiments or to that which is claimed herein. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
This application claims priority to U.S. application No. 62/428,120 filed Nov. 30, 2016, the entire contents of which are incorporated by reference in its entirety.
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