Cooking appliance
Patent Information
- Application Number
- EP2024710704
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-03-09
- Filing Date
- 2024-03-07
- Publication Date
- 2026-01-14
AI Technical Summary
Conventional electrically heated griddle plates suffer from poor heat transfer and significant heat losses due to circular heating elements located underneath a conductive plate, leading to inefficiency and high energy consumption.
A griddle plate assembly comprising three plates - a top conductive plate, a middle plate with embedded heating elements, and a bottom insulating plate, where the heating elements are securely fitted within slots in the middle plate, ensuring maximum contact area and efficient heat transfer, with the bottom plate minimizing heat loss.
This configuration allows for efficient heat distribution across the cooking surface, achieving high temperatures with lower energy input, increased flexibility in cooking conditions, and easier cleaning, while reducing energy consumption and heat loss.
Smart Images
Figure EP2024056073_12092024_PF_FP_ABST
Abstract
Description
[0001] Cooking Appliance
[0002] The present invention relates to an electrically heated cooking appliance.
[0003] Numerous forms of electrically heated cooking appliances are available. In a traditional electric hob, a pan can be placed directly onto an electrically powered heating element. Alternatively, a heating element may heat a top plate on which a pan is placed. Another form of cooking appliance is a griddle plate in which a heated plate is provided onto which food is placed directly.
[0004] In a conventional electrically heated griddle plate cooking appliance, the heating elements are usually circular in cross section and are located underneath a conductive plate on to which the food is placed. Therefore, heat transfer to the conductive plate can be poor, heat losses can be significant, and the appliance is not particularly energy efficient.
[0005] The present invention provides a cooking appliance as set out in claim 1 . Further features are set out in the dependent claims.
[0006] The invention will now be described in detail, by way of example only, with reference to the accompanying drawings in which:
[0007] Figure 1 is a perspective view of one embodiment of a cooking appliance in accordance with the present invention;
[0008] Figure 2 is a perspective view of the top section of the cooking appliance with the top plate removed;
[0009] Figure 3 is a plan view of the griddle plate assembly showing parts beneath the top plate in phantom lines;
[0010] Figure 4 is a perspective view of one of the heating elements;
[0011] Figure 5 is a perspective view from below of the griddle plate assembly;
[0012] Figure 6 is a cross-section through the cooking appliance of Figure 1 ; and Figure 7a is a cross-section through the griddle plate assembly;
[0013] Figure 7b is an enlarged view of part of the cross section of the griddle plate assembly; and
[0014] Figure 8 illustrates a cross section through another embodiment of griddle plate assembly. A cooking appliance 10 in accordance with the present invention comprises a griddle plate assembly 12 which may be surrounded by a perimeter wall 14 and mounted on a base 16. The base 16 may be placed on top of an existing worktop, or the cooking appliance 10 may be designed to be built into a worktop.
[0015] The griddle plate assembly 12 has an upper surface, on which food items are placed in use for cooking, and a lower surface. The upper surface of the griddle plate assembly 12 may be a smooth, flat, continuous surface. One or more electrically powered heating elements 24 (shown in Figure 2) are located within the griddle plate assembly 12 between the upper and lower surfaces.
[0016] The griddle plate assembly 12 comprises a plurality of layers, as best seen in Figures 7a and 7b. In an embodiment, griddle plate assembly 12 comprises a first plate 18 with an upper surface 18a and a lower surface 18b. The first plate 18 is uppermost in the griddle plate assembly 12 and its upper surface 18a forms the upper surface of the griddle plate assembly 12 on to which food is placed in use for cooking. Thus, the first plate 18 can be referred to as the top plate of the griddle plate assembly 12.
[0017] A second plate 22 is provided with an upper surface 22a and a lower surface 22b. The second plate 22 is lowermost in the griddle plate assembly 12 and its lower surface 22b forms the lower surface of the griddle plate assembly 12. Thus, the second plate 22 can be referred to as the bottom plate of the griddle plate assembly 12.
[0018] In addition, a third plate 20 is provided, with an upper surface 20a and a lower surface 20b. The third plate 20 is sandwiched between the first and second plates 18,22 and thus can be referred to as the middle plate of the griddle plate assembly 12.
[0019] The plates 18, 20, 22 are in contact with one another so that the lower surface 18b of the first (top) plate 18 contacts the upper surface 20a of the third (middle) plate 20, and the lower surface 20b of the third (middle) plate 20 contacts the upper surface 22a of the second (bottom) plate 22. In use, food items are placed directly onto the upper surface 18a of the first plate 18.
[0020] The top and middle plates 18, 20 are formed of a conductive material, such as a metal. The heating elements 24 are located in the middle plate 20 as described below. The bottom plate 22 is formed of an insulating material and therefore prevents or reduces heat loss from the lower surface of the griddle plate assembly 12.
[0021] As shown in Figure 2, two (or more) middle plates 20 may be provided side by side, i.e. laterally or horizontally adjacent to one another, but with a gap 32 between them. These middle plates 20 may be sandwiched between a single top plate 18 and one or more bottom plates 22. The heating elements 24 in one middle plate 20 may be controlled separately from the heating elements 24 in another middle plate 20. This allows heat to be supplied to only one part of the top plate 18 if a smaller cooking area is required. This also allows one part of the top plate 18 to be heated to a different temperature to another part. This increases efficiency and allows for flexibility in the cooking conditions provided. Using a single top plate 18 with no joints of gaps allows for easier cleaning of the griddle plate assembly.
[0022] The middle plate 20 is formed with one or more slots 26 in which the heating elements 24 are located. In the example shown in Figures 2 and 3, three heating elements are provided in each middle plate 20, although the number and shape of heating elements used can be varied to suit the size of the cooking appliance 10. Each slot 26 is formed with straight, vertical sides and may extend right through the plate 20 from the upper surface 20a to the lower surface 20b. When the three plates 18, 20, 22 are sandwiched together, the lower surface 18a of the top plate 18 closes the top of the slot 24. Similarly, the upper surface 22a of the bottom plate 22 closes the bottom of the slot 24. In this way, an enclosed channel 28 is provided. The width of the slot 24 may be equal to the depth of the slot (i.e. thickness of the middle plate 20) so that the enclosed channel 28 has a square crosssection. However, the channel 28 could be defined such that the width of the slot 24 is not equal to the depth of the slot and the cross-sectional shape is rectangular. This is shown in Figures 7a and 7b, and although some small gaps are illustrated between the various components for the sake of clarity and to show the various surfaces, in use the plates 18, 20, 22 are clamped tightly together, as discussed below.
[0023] Each heating element 24 comprises an elongate bar of conductive material which is shaped and dimensioned to fit closely into a slot 26. Therefore, the heating element 24 is also formed with a square or rectangular cross section so that the heating element 24 contacts the walls defining the enclosed channel 28. The sides of the heating element 24 contact the sides of the slot 24 in the middle plate 20. The top of the heating element 24 contacts the lower surface 18b of the top plate 18. The bottom of the heating element 24 contacts the upper surface 22a of the bottom plate 22. Thus, there is a large contact area between the heating element 24 and the top and middle plates 18, 20 to increase the efficiency of heat transfer. In this way, a high temperature of up to about 300°C can be achieved on the cooking surface, i.e. the top surface 18a of the top plate 18.
[0024] The slot 26 may be formed in any convenient shape. In the embodiment illustrated, the slot 26 is shaped as an elongated loop with two straight sides joined by arcuate ends. There may be a plurality of such loops across the area of the second plate 20. As in the example of Figure 2, three such loops may be provided. Alternatively, the slot 26 may follow a serpentine path which extends across the area of the second plate 20. A heating element 24 is provided in each slot 26 so that even heating can be provided across the area of the top plate 18. Each heating element 24 conforms to the looped shape (or other relevant shape) of the slot 26 to fully occupy the slot 26. Thus, as shown in Figure 4, each heating element may have two straight sides 24a, joined by arcuate ends 24b. The free ends of the heating elements form two legs 24c which extend perpendicular to the sides 24a and ends 24b. A widened area 30 of the slot 26 in the middle plate 20 may be provided to receive the ends of the heating element 24 and openings may be formed in the bottom plate 22 beneath the widened area 30 to allow for connection of the legs 24c of the heating element 24 to an electrical power supply and the controls of the cooking appliance 10, which may be provided in the base 16.
[0025] In one example, the cross section of each heating element 24 may be 8 mm along each side. The length of each loop between the two opposing arcuate ends 24b may be 518 mm. The radius of each arcuate end 24b may be 34 mm. However, other dimensions and configurations for the heating elements 24 can be used to suit the desired application.
[0026] As noted above, the top, middle and lower plates are clamped tightly together to ensure good contact with the heating elements 24. For example, as shown in Figure 5, weld studs 44 may be provided on the lower surface 18b of the top plate 18, which extend through openings 40, 42 in the middle and lower plates 20, 22. The weld studs 44 may have an external thread, to which a bolt can be applied and tightened up evenly to achieve uniform pressure of the heating elements 24. A grid of weld studs 44 and corresponding openings 40, 42 may be provided across the griddle plate assembly 12, as seen in Figures 2 and 3. This is important to ensure even clamping of the plates across the whole area. In particular, some of the openings 40 are provided inside the loop of each heating element 24, with at least one opening 40 closely adjacent to the radially inner side of each arcuate section 24b, and at least one opening 40 adjacent to each side 24a. A number of openings 42 are also provided in the region external to the loop of each heating element 24.
[0027] Due to the square or rectangular cross-sectional shape of the heating elements 24, the close fit into the channels 28, and the tight and even clamping of the plates 18, 20, 22 there is a large contact area between the heating elements 24 and the conductive parts of the griddle plate assembly 12, in particular the top and middle plates 18, 20. This ensures optimum heat transfer to the first plate 18, ensuring greater efficiency of the cooking appliance 10 and a lower energy input requirement to achieve a given temperature on the upper surface of the top plate 18. Clamping close to the arcuate ends 24b, where there is a higher concentration of heating, ensures the heat can be efficiently conducted away from the heating elements 24 to the top and middle plates 18, 20 to avoid overheating and failure of the heating elements 24. The bottom plate 22 prevents heat losses below the griddle plate assembly 12, further increasing efficiency.
[0028] Forming the griddle plate assembly 12 in this way, with three plates sandwiched together and cutting slots in the middle plate for the heating elements provides an efficient way to manufacture the cooking appliance 10. The plates 18, 20, 22 may be cut to the required size and the slots 26 and openings 40,42 formed by techniques such as water or laser cutting. This is simpler and more cost effective that machining channels into a surface of plate.
[0029] It will be appreciated that the precise configuration of the griddle plate assembly 12 can be varied. For example, in a three-plate construction as shown in Figure 8, in addition to the slot 24 through the thickness of the middle plate 20, a corresponding shallow slot 32 may be provided in the lower surface 18b of the upper plate 18 and / or in the upper surface 22a of the lower plate 22, to create a deeper channel 28. In use a heating element 24 may extend a short distance above and / or below the middle plate 20 and into the or each additional shallow slot 32. At one side of the cooking appliance (typically towards the front in use), the top plate 18 may extend beyond the middle and lower plates 20, 22 as seen in Figure 3. Therefore, a region 50 of the top plate 18 is not directly over the heating elements 24. In this region 50 the temperature of the cooking surface will drop off significantly. Therefore, the region 50 can be used as a resting zone, on which cooked food items may be placed in order to res before serving.
[0030] Thus, the present invention provides an improved electrically heated cooking appliance which requires less energy to achieve a desired cooking temperature on the upper surface of the griddle plate.
Claims
CLAIMS:1 . A cooking appliance comprising a griddle plate assembly having an upper surface, on which food items are placed in use, and a lower surface, at least one channel defined within the griddle plate assembly between the upper surface and the lower surface, and an electrically powered heating element located in the or each channel, wherein the griddle plate assembly comprises a first plate of conductive material with an upper surface and a lower surface, and the upper surface of the first plate forms the upper surface of the griddle plate assembly; a second plate of insulating material with an upper surface and a lower surface, and the lower surface of the second plate forms the lower surface of the griddle plate assembly; and a third plate of conductive material with an upper surface and a lower surface, the third plate sandwiched between the first plate and the second plate, and wherein the third plate defines at least one slot extending through the third plate from its upper surface to its lower surface, and the first and second plates respectively close the top and bottom of the or each slot to define the or each channel, and the or each channel is square or rectangular in cross section and the or each heating element is square or rectangular in cross section and is dimensioned such that all four sides of the heating element contact the walls of the channel.
2. A cooking appliance as claimed in claim 1 , wherein the third plate comprises two or more third plates located laterally adjacent to one another.
3. A cooking appliance as claim in claim 2, wherein there is a gap between each of the laterally adjacent third plates.
4. A cooking appliance as claimed in any of claims 1 to 3, wherein the third plate defines openings through which the or each heating element is connectable to a source of electrical power.
5. A cooking appliance as claimed in any preceding claim, further comprising a plurality of clamping devices which clamp the first, second and third plates together at a plurality of locations.
6. A cooking appliance as claimed in claim 5, wherein each clamping device comprises a weld stud which is attached to the lower surface of the first plate which extends through openings in the second and third plates, and a bolt securable to each weld stud.
7. A cooking appliance as claimed in claim 5 or claim 6, wherein each heating element comprises at least one straight section and at least one arcuate section.
8. A cooking appliance as claimed in claim 7, wherein at least one clamping device is located adjacent to a radially inner side of each arcuate section.
9. A cooking appliance as claimed in any preceding claim, wherein a region of the first plate extends beyond the second and third plates.
10. A cooking appliance as claimed in any preceding claim, wherein at least one slot is formed in the lower surface of the first plate and / or in the upper surface of the second plate, corresponding to the at least one slot in the third plate.