US20220275948A1

US20220275948A1 - Convection Oven with Removable Grill Plate

Info

Publication number: US20220275948A1
Application number: US17/653,060
Authority: US
Inventors: Luo Fei; Zeng Qing Ping; Kim Jong Rok; Eubene Sin; Byung Gab Choi
Original assignee: Nuwave LLC
Current assignee: Nuwave LLC
Priority date: 2021-03-01
Filing date: 2022-03-01
Publication date: 2022-09-01

Abstract

A cooking appliance having a housing which includes a cooking chamber suitable for convection cooking and grilling. The appliance includes a plurality of heat sources positioned within the housing to generate heat within the cooking chamber, a power source for powering the plurality of heat sources, at least one fan for moving air within the cooking chamber, a removable grill plate which secures within the cooking chamber, and an outlet for connecting the removable grill plate to the power source when positioned within the cooking chamber.

Description

RELATED APPLICATION

The present application claims the filing priority of U.S. Provisional Application No. 63/154,935, titled “Convection Oven With Removable Grill Plate” and filed on Mar. 1, 2021. The '935 application is hereby incorporated by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to cooking appliances, specifically countertop cooking appliances. More specifically, the invention relates to countertop convection ovens with a removable grilling plate.

BACKGROUND OF THE INVENTION

Convection ovens are well-known in the art. Convection cooking—i.e., cooking with heated air—creates a dry atmosphere within a cooking chamber that caramelizes food sugars faster when roasting. Foods, like meats and vegetables, that are cooked using convection get browner, but the interiors stay moist. Further, convection cooking saves energy because food cooks faster in a convection oven, and generally at a lower temperature. Convection ovens are typically a bit more energy efficient than a regular oven.
Grilling is quite different from convection cooking, as it occurs with application of direct heat (radiation or conduction) to the food being grilled and can, therefore, be done in an open appliance. Grilling is also typically done at higher temperatures than oven baking, whether regular or convection. In many instances, food can be grilled to sear outer surfaces and then finished in an oven.
However, in countertop cooking, the process of grilling and then convection oven cooking has always required two different appliances. Where countertop space is limited, having a single appliance which is versatile enough to handle both grilling and convection cooking would be of significant value, saving time, money, and space. Accordingly, a countertop appliance which is capable of both grilling and convection oven cooking is needed.
Further, two keys to grilling any food well are to (1) maintain a consistent cooking temperature for an entire cooking cycle, and (2) evenly distribute heat to the food being grilled. The first goal has to do with avoiding big temperature drops during the grilling process—i.e., as a result of adding food to the grill surface or turning a grilling food item over. The second goal has to do with avoiding hot and cold spots on a grilling surface—i.e., due to concentrated heat sources that are ineffective across an entire grill surface. Prior art cooking appliances have difficulty accomplishing both of these goals. That is, the cooking surfaces for many appliances fluctuate too much during a cooking cycle, and food cooking surfaces—e.g., grills—for prior art cooking appliances are designed such that heat is often localized, causing uneven grilling.
Until the invention of the present application, these and other problems in the prior art went either unnoticed or unsolved by those skilled in the art. By combining multiple functions into a single countertop appliance, versatility and transportability are improved, and cost and space requirements are reduced.
The present invention provides a countertop cooking appliance which performs multiple functions with without sacrificing quality, design, style or affordability.

SUMMARY OF THE INVENTION

There is disclosed herein an improved cooking appliance which avoids the disadvantages of prior devices while affording additional structural and operating advantages.
Generally speaking, the cooking appliance comprises a housing having formed therein a cooking chamber, a plurality of heat sources positioned within the housing to generate heat within the cooking chamber, a power source for powering the plurality of heat sources, at least one fan for moving air within the cooking chamber, a removable grill plate which secures within the cooking chamber, and an outlet for connecting the removable grill plate to the power source when positioned within the cooking chamber.
A grill plate for detachable connection to a power source within the disclosed cooking appliance is also set forth. Generally speaking, the grill plate comprises a top surface comprising a plurality of raised ribs, a heating element within the grill plate positioned so as to heat the top surface, and a connector which allows the grill plate to be attached and detached from the cooking appliance and electrically couples the heating element to a power source for the cooking appliance, wherein each of the plurality of raised ribs has a height and a width, and the height is equal to the width.
In specific embodiments, the second and third heating sources are inactive in the cooking appliance when the grill plate is engaged with the power source within the cooking chamber. Power can be divided between the grill plate and the first heating source. A user can alter the power distribution between 0-100% for each of the components.
In specific embodiments of the grill plate of the cooking appliance, the plurality of raised ribs on the top surface comprises a height (h) and a width (w), and the height (h) is preferably approximately equal to the width (w).
Preferably the height (h) and width (w) of each of plurality of raised ribs is in the range of from 5 mm to 8 mm. More preferably, the height of each of the plurality of raised ribs is in the range of from 5.5 mm to 8 mm and the width is in the range of 5.0 to 7.0 mm. Most preferably, the height of each rib is 6.5 mm, and the width of each rib is 6.0 mm.
In specific embodiments, the plurality of raised ribs are preferably equidistantly spaced a distance from one another on the top surface, the distance being within the range of 10.2 to 13.8 mm and most preferably 12 mm.
These and other aspects of the invention may be understood more readily from the following description and the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of facilitating an understanding of the subject matter sought to be protected, there are illustrated in the accompanying drawings, embodiments thereof, from an inspection of which, when considered in connection with the following description, the subject matter sought to be protected, its construction and operation, and many of its advantages should be readily understood and appreciated.

FIG. 1 is a perspective view of a prior art countertop convection oven;

FIG. 2 is a front view of the prior art countertop convection oven shown in FIG. 1;

FIG. 3 is a close-up view of an embodiment of a user interface control panel for the disclosed countertop convection oven;

FIG. 4 is a front perspective view of another embodiment of a countertop convection oven with an insertable grill plate as described herein;

FIG. 5 is a close-up view of an embodiment of the door sensor for the disclosed countertop convection oven;

FIG. 6 is a schematic illustrating an embodiment of a countertop convection oven with insertable grill plate as described herein;

FIG. 7A is a top view of an embodiment of an insertable grill plate;

FIG. 7B is a close-up view of a portion of the grill plate of FIG. 6A; and

FIG. 8 is a schematic of a cut-away section of an embodiment of a grill plate to illustrate relative dimensions;

FIG. 9 is front edge view of the grill plate shown in FIG. 6A;

FIG. 10 is a temperature/time graph corresponding to data acquired during grilling using a prior art cooking appliance;

FIG. 11 is a temperature/time graph corresponding to data acquired during grilling using a cooking appliance of the present disclosure;

FIG. 12 is a temperature profile of an embodiment of the present disclosure;

FIG. 13 is a temperature profile for a prior art cooking appliance;

FIG. 14 is an electronic schematic of an embodiment of the disclosed cooking appliance illustrating operation when the door switch mechanism is activated; and

FIG. 15 is an electronic schematic of an embodiment of the disclosed cooking appliance illustrating operation when a temperature drop is detected.

DETAILED DESCRIPTION OF THE INVENTION

While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail at least one preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to any of the specific embodiments illustrated.
Referring to FIGS. 1 and 2, a standard prior art convection oven appliance 100 is shown. This appliance 100 is designed to be placed on a countertop and plugged into a power outlet. A built-in heat source is used to heat air within an interior cooking chamber 102 while a fan 104 circulates the heated air. A control panel 106 on the exterior of the appliance 100 allows a user to manually set cooking temperatures, cooking time, fan speed, and other cooking parameters. The control panel 106 may even provide pre-set cooking selections, such as “sear,” “reheat,” “defrost,” and the like.
Embodiments of the present invention are illustrated in FIGS. 3-5, where the cooking appliance is generally designated by the numeral 10. The particular illustrated cooking appliance 10 is of a countertop convection oven with a removable grill plate 50.
As can be seen in FIGS. 3-6, the cooking appliance 10 includes a housing 12 with a defined cooking chamber 14. A front opening of the chamber 14 is covered by a downward pivoting door 16, preferably with a glass window 18. A plurality of tray/rack supports 20 may be provided along sidewalls 22 of the chamber 14 to allow the insertion and removal of cooking trays, wire racks 24, and a removable grill plate 50 (see FIG. 4). A control panel 26 is positioned on a front face of the appliance 10, either above or below the door 16.
The preferred cooking appliance 10 includes three heating sources 30. A first heating source 30A is positioned at the top surface of the cooking chamber 14 within the housing 12, while a second heating source 30B is positioned at the bottom surface of the cooking chamber 14 within housing 12. A third heating source 30C is positioned at a rear wall of the cooking chamber 14 within housing 12 and includes a fan 32 for circulating the heated air within the cooking chamber 14. Additional fans may be provided. The positioning of the three heating sources 30 has been found to provide the most advantageous cooking. However, other locations for any one or all of the heating sources 30 may be possible. Additional heating sources may also be used, as necessary. Each of the heating sources 30A-C and the fan 32 are electrically connected to the power source—via standard wiring and use of, for example, AC plug 34—to facilitate powering of these components.
FIG. 3 illustrates a user interface control panel 26 provided on an outward front-face surface of the cooking appliance 10. The control panel 26 provides control of each of the heating sources 30, including the grill plate 50 when inserted. In a preferred embodiment, the bottom heating source 30B and rear heating source 30C are each deactivated when the grill plate 50 is inserted into the cooking chamber 14 and connected to the power source outlet 36. The control panel 26 allows a user to enter time, temperature, cooking power, etc. as just some of the possible control inputs.
FIGS. 4-6 show a grill plate 50 positioned in a bottom slot of the cooking appliance 10. The grill plate 50 provides an alternative direct heat source to the cooking appliance 10 for both grilling and combination cooking techniques.
When grilling, power is directed solely to the grill plate 50. If preheating before grilling, the grill plate 50 and top heating source 30A can be used to quickly reach a target grilling temperature. However, once the preheat is complete, only the grilling plate 50 is used. Prior art systems typically use air fry heaters or convection oven heaters while grilling, which has been found to dry out meats and results in less flavorful food product.
Combination cooking, aka “combo cooking,” allows a user to cook food using direct bottom heat from the grill plate 50 combined with top convection heat from the first heat source 30A. The user can adjust power to the grill plate 50 and the top heating source 30A, preferably in 5% increments, for 100% total power—e.g., 65% power to grill plate 50 and 35% power to heating source 30A.
The “Combo” cooking feature is only available when the grill plate 50 is connected to the outlet 36 (FIG. 4). In order to engage the grill plate 50, the user must press the [on/off] button 60 and then the [Combo] button 62. A 70% power to the grill plate 50 and 30% power to the top heating source 30A is a preferable default setting. However, other default settings are possible, and the power percentages can be manually adjusted during use by turning dial 64. When the dial 64 is turned to the right [+], power increases to the top heating source 30A up to 100%, while left [−] increases power to the grill plate 50 up to 100%.
As shown in FIG. 5, one of the key features of the disclosed cooking appliance 10 and grill plate 50 combination includes a door switch 40. When the pivoting door 16 is in an open position—even partially open—the switch 40 signals a controller (not shown) to increase power to the grill plate 50 and/or the first or top heating source 30A. The increase in power results in an increase in temperature at the grill plate 50, which is intended to overcome the loss of heat due to the open door and/or the placement of a much cooler food item, e.g., steak, chicken, pork. FIGS. 14 and 15 show schematically the components which are used to trigger the power increase as a result of a door open (FIG. 14) or temperature drop (FIG. 15) condition.
Preferably, a 100° F. increase for less than five minutes, most preferably approximately two minutes (±10 seconds), is sufficient to overcome the heat loss. This power/heat boost is a particularly useful feature for grilling, as it is necessary to open the appliance door 16 to add and turn over food items, such as burgers, steaks, chicken, and the like. Maintaining the grill temperature ensures a proper searing temperature, which is critical to locking in natural food juices during grilling. While a 100° F. increase for two minutes is preferred, certainly increases of less or more heat for longer or shorter periods may be suitable for other applications. Data in support of this feature, as compared to a prior art system, is shown in TABLE 1 below.
Referring to FIGS. 7A, 7B, 8 and 9, the grill plate 50 can be more readily understood. As previously stated, the grill plate 50 provides a direct heating source for food when place onto the connected grill plate 50. In a preferred embodiment, a connector 52 on a back edge of the grill plate 50 connects to a corresponding outlet connector 36 within the cooking chamber 14 and allows the grill plate 50 to receive power from the power source.
In a preferred embodiment, the grill plate 50 includes a top surface 54 having a plurality of raised ribs 56—i.e., metal or ceramic ribs, as opposed to pork or beef ribs. The ribs 56 have specific dimensions which facilitate maintaining a consistent temperature during grilling. First, the ribs 56 are equidistantly spaced a distance (x) on the grill plate 50, approximately 10.2 mm to 13.8 mm, measured center to center. Most preferably, the distance is approximately 12 mm, center to center. Further, the thickness or width (w) of each rib 56 is approximately the same as the height (h) of the rib 56. The width (w) and height (h) of each rib should fall within the range of 5 mm to 8 mm. The range for the height (h) is preferably 5.5 mm to 8 mm, with a most preferred height (h) of 6.5 mm. Similarly, the width (w) has a preferred measure in the range of 5 mm to 7 mm, with 6 mm being the most preferred width (w). By “approximately” it is meant that to an observer, without measurement, the dimensions appear equal—i.e., w=h. This near 1:1 relationship combined with the rib spacing has been found to help minimize heat loss of the grilling surface 54, which often happens when food is added directly to the grill plate 50. The loss of heat results in inferior grilling. Significant loss of heat at the grilling surface during grilling can have a significant impact on the quality and taste of grilled food.
The grilling surface also comprises a plurality of holes 58 that release oil and food drippings into a pan below the grill plate 50. Draining away such material helps maintain the grill plate temperature as well. The plurality of holes 58 also result in less surface area to heat, which helps regulate the temperature, unlike prior art devices.
TABLE 1 below shows side-by-side temperature data of a prior art grilling surface (left side of table) and the grilling surface of an embodiment of the present invention (right side of table). The data for the two systems is also provided in graph form, as shown in FIGS. 10 and 11.
To acquire the data provided in TABLE 1, a 16 oz. 1.5-inch steak was to be cooked on each grill—ambient outside temperature of 67° F. (±1.0° F.). The present invention completed preheat at row A (8:20), while the prior art grill completed preheat at row B (8:50). The steaks were turned at internal temperatures of 75° F., as shown by row C (14:20) and row D (15:10), for the present invention and prior art systems, respectively. Grilling was completed at row E (17:40) and row F (19:10). Each of the critical points A-F are indicated on the graphs of FIGS. 10 and 11 as well.

TABLE 1

Time	PRIOR ART GRILL	PRESENT GRILL

(mm:ss)	Left	Center	Right	Inside	Left	Center	Inside

00:00	71.60	71.60	71.60	70.88	71.96	73.04	71.06
01:00	130.10	120.20	112.64	169.70	178.34	191.30	134.06
02:00	189.32	171.50	160.16	246.38	255.20	274.64	197.96
03:00	256.82	211.64	206.24	299.48	334.40	358.16	264.74
04:00	310.82	261.86	298.40	347.00	402.80	427.64	326.66
05:00	340.70	353.12	337.64	379.04	442.04	464.90	372.20
06:00	370.22	377.60	359.60	400.28	471.56	493.34	409.46
07:00	401.54	395.42	385.52	409.46	499.28	519.98	436.10
08:00	415.04	413.24	403.88	417.74	522.50	543.74	457.70
08:10	413.42	413.42	404.78	413.60	525.92	546.80	461.12
08:20	418.64	418.28	410.36	419.18	529.52	550.58	462.92	(A)
08:30	426.02	424.76	417.38	430.52	431.78	447.80	364.46
08:40	435.56	431.78	424.76	440.06	387.50	377.96	397.22
08:50	417.02	402.80	382.46	382.46	369.50	364.64	416.66	(B)
09:00	111.38	131.36	109.22	375.80	357.08	356.54	417.20
09:30	127.58	129.74	123.62	410.00	348.26	342.68	414.86
10:00	134.42	141.26	126.50	431.60	345.02	350.60	414.32
10:30	154.40	161.24	132.44	448.34	352.04	357.62	413.42
11:00	158.18	204.26	159.80	442.22	348.62	361.94	414.50
11:30	175.46	226.22	182.30	436.82	353.84	364.46	413.24
12:00	204.62	255.02	205.88	452.48	369.14	368.60	412.52
12:30	223.16	296.60	210.92	457.88	368.60	371.48	409.46
13:00	228.38	310.46	218.30	444.92	381.38	374.36	406.94
13:30	229.46	299.48	229.64	450.14	388.22	375.26	404.60
14:00	235.04	292.10	228.92	457.52	392.72	385.88	402.80
14:10	233.24	297.14	230.72	455.72	387.14	386.42	401.90
14:20	237.02	297.14	223.02	451.76	386.06	340.70	344.84	(C)
14:30	233.60	299.48	235.76	456.44	300.02	288.50	356.00
14:40	231.62	298.40	239.00	446.90	293.54	300.74	386.78
14:50	234.68	298.58	238.64	445.10	279.68	310.64	392.90
15:00	235.22	300.74	241.52	449.06	269.42	308.66	393.44
15:10	233.24	299.12	239.72	371.12	255.74	315.14	393.80	(D)
15:30	216.68	246.74	352.94	413.96	253.58	336.56	394.70
16:00	235.94	249.80	365.90	415.22	251.60	347.36	394.88
16:30	237.02	252.86	389.48	440.42	269.06	354.20	396.14
17:00	241.34	258.08	396.68	450.86	277.16	370.94	397.40
17:30	244.40	257.90	387.68	444.02	284.72	380.30	398.30
17:40	244.76	257.36	388.94	444.56	282.56	376.52	398.84	(E)
18:00	245.84	259.70	389.30	448.70	276.26	364.46	399.38
18:30	244.76	260.24	390.20	454.82	276.62	370.40	399.74
19:00	243.50	258.26	380.30	453.02	264.20	360.86	399.38
19:10	243.14	253.04	375.98	446.00	263.48	356.36	401.54	(F)

The temperature data shows that the prior art grill reached a temperature (° F.) of 417/402/382 after 8:50 (mm:ss) as measured at the left, center, and right areas of the grill surface, respectively. The temperature immediately dropped to 111/131/109 ° F. upon addition of the steak. This represents a drop of approximately 305/271/273 ° F. or roughly an average temperature loss of 70% (73%/67%/71%). Further, the grilling temperature did not return to a proper grilling temperature of approximately 230° F. for at least three and a half minutes (13:00 min mark).
Conversely, the present invention reached a temperature of 530/550 ° F. (left and center) at 8:20 and dropped to 431/447° F. after addition of the steak. The temperature loss of 98/103° F. represents an average of under 19% drop (i.e., 18.5%/18.7%). More importantly, the grill surface returned to a proper grilling temperature of 370/365° F. by the 8:50 mark—i.e., in less than 30 seconds. Finally, grilling of the steak was completed by the present invention at least 90 seconds prior to the prior art system.
During grilling, the present cooking appliance 10 adjusts the power level of the two heating elements together—i.e., grill plate 50 and heating source 30A—in order to maintain the grill plate 50 surface temperature. The result is a steady, even temperature profile as shown in FIG. 12. With reference to FIG. 14, as soon as the door 16 is opened, the door switch 40 activates. This triggers the controller IC 70 to provide full power (1000W) to the grill plate 50 and fan 32 for approximately two minutes. Likewise, if the temperature sensor for the grill plate 50, preferable an NTC thermistor 72, reacts to a temperature drop (e.g., 5-10° F.), the controller IC 70 is triggered to provide full power (1000W) to the grill plate 50 and fan 32 for approximately two minutes. Of course, as previously noted, these numbers are exemplary. That is, the power increase used may vary and the trigger point may be less than 5° F. or more than 10° F. for specific cooking operations.
Conversely, prior art devices never use a top and bottom grill heater together. Instead, they work alternately to create a fluctuating grill surface temperature, as shown in FIG. 13.
The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. While particular embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the broader aspects of applicants' contribution. The actual scope of the protection sought is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.

Claims

What is claimed is:

1. A cooking appliance comprising:

a housing having formed therein a cooking chamber;

at least three heat sources positioned within the housing to generate heat within the cooking chamber;

a power source for powering the three heat sources;

at least one fan for moving air within the cooking chamber;

a removable grill plate which secures within the cooking chamber, the removable grill plate having a top surface, the top surface having a plurality of raised ribs; and

an outlet for connecting the removable grill plate to the power source when positioned within the cooking chamber.

2. The cooking appliance of claim 1, wherein each of the plurality of raised ribs comprises a height and a width, and the height is equal to the width.

3. The cooking appliance of claim 1, wherein each of the plurality of raised ribs are equidistantly spaced a distance from one another on the top surface, wherein the distance is within the range of 10.2 to 13.8 mm.

4. The cooking appliance of claim 3, wherein the distance is 12 mm.

5. The cooking appliance of claim 2, wherein the height and width of each of plurality of raised ribs is in the range of from 5 mm to 8 mm.

6. The cooking appliance of claim 5, wherein the height of each of the plurality of raised ribs is in the range of from 5.5 mm to 8 mm.

7. The cooking appliance of claim 5, wherein the height of each of the plurality of raised ribs is 6.5 mm.

8. The cooking appliance of claim 2, wherein the width of each of the plurality of raised ribs is in the range of from 5.0 mm to 7.0 mm.

9. The cooking appliance of claim 8, wherein the width of each of the plurality of raised ribs is 6.0 mm.

10. The cooking appliance of claim 1, further comprising a door open switch.

11. The cooking appliance of claim 10, wherein the door open switch is configured to trigger an increase of power to the removable grill plate when activated.

12. The cooking appliance of claim 11, wherein the increase of power has a limited duration.

13. The cooking appliance of claim 12, wherein the limited duration is less than 5 minutes.

14. The cooking appliance of claim 13, wherein the limited duration is approximately 2 minutes.

15. A grill plate for detachable connection to a power source within a cooking appliance, the grill plate comprising:

a top surface comprising a plurality of raised ribs;

a heating element within the grill plate positioned so as to heat the top surface; and

a connector which allows the grill plate to be attached and detached from the cooking appliance and electrically couples the heating element to a power source for the cooking appliance;

wherein each of the plurality of raised ribs has a height and a width, and the height is equal to the width.

16. The grill plate of claim 10, wherein each of the plurality of raised ribs are equidistantly spaced a distance from one another on the top surface, wherein the distance is within the range of 10.2 to 13.8 mm.

17. The grill plate of claim 11, wherein the distance is 12 mm.

18. The grill plate of claim 10, wherein the height and width of each of plurality of raised ribs is in the range of from 5 mm to 8 mm.

19. The grill plate of claim 13, wherein the height of each of the plurality of raised ribs is in the range of from 5.5 mm to 8 mm.

20. The grill plate of claim 14, wherein the height of each of the plurality of raised ribs is 6.5 mm.

21. The grill plate of claim 13, wherein the width of each of the plurality of raised ribs is in the range of from 5.0 mm to 7.0 mm.

22. The grill plate of claim 16, wherein the width of each of the plurality of raised ribs is 6.0 mm.