Electrical household appliance and operating method

Abstract

The invention relates to an electrical household appliance (50) comprising a cooking plate (11), a heating element (9) for the cooking plate (11), a block (10) for diffusing heat against the cooking plate (11), characterized in that the heating element (9) is at the same time in contact with the diffuser block (10) and spaced apart from and facing the cooking plate, the heating element (9) being capable of heating the cooking plate (11) by a double heat flow by conduction through the diffuser block (10) and by radiation. The invention also relates to a method for operating the appliance.

Description

[0001] HOUSEHOLD APPLIANCE AND OPERATING METHOD

[0002] technical field

[0003] The present invention relates to a household appliance and a method of operation.

[0004] Previous art

[0005] There are household appliances that allow you to cook food, such as dough balls, pastry dough, and to grill various foods such as slices of meat, vegetables, etc. However, the energy transfer for cooking food in household appliances is neither efficient nor regular.

[0006] Therefore, there is a need for a household appliance that allows for more efficient regulation of cooking temperature.

[0007] Summary of the invention

[0008] To this end, the invention proposes a household appliance comprising: a cooking plate, a heating element of the cooking plate, a heat diffuser block against the cooking plate, characterized in that the heating element is both in contact with the diffuser block and away from and facing the cooking plate, the heating element being capable of heating the cooking plate by a double flow of heat by conduction through the diffuser block and by radiation.

[0009] According to one variant, the heating element has a surface that is partly cylindrical and partly flattened, the partly cylindrical surface being in contact with the diffuser block and the flattened surface being away from and facing the cooking plate.

[0010] According to one variant, the heating element and the diffuser block are independent of the cooking plate.

[0011] According to one variant, the diffuser block has a groove with an opening towards the cooktop, the heating element being in the groove and away from and facing the cooktop through the opening of the groove.

[0012] In one version, the appliance also includes compression springs that hold the diffuser block against the cooktop. In another version, these compression springs ensure that the diffuser block maintains optimal and consistent contact with the cooktop.

[0013] According to one variant, the diffuser block and the heating element are mobile, with the compression springs ensuring thermal contact of the diffuser block against the cooking plate.

[0014] According to one variant, the device also includes a thermostat regulating the temperature of the cooking plate, the thermostat extending through a passage zone in the diffuser block.

[0015] According to one variant, the thermostat has a bulb, the bulb being under pressure against the cooking plate.

[0016] According to one variant, the device includes an axis on which the thermostat is placed and a spring that forces the thermostat towards the cooking plate, the bulb being put under pressure against a central area of ​​the cooking plate.

[0017] According to one variant, a lower part of the bulb is a crown surrounding a central recess and an upper part of the bulb is closed to make contact with a bimetal of the thermostat, the bulb and the bimetal being thermally protected from the heating element and the diffuser block.

[0018] In one version, the cooking plate(s) are removable.

[0019] According to one variant, the device also includes a heat reflector, with the diffuser block arranged between the cooking plate and the reflector.

[0020] According to one variant, the diffuser block is separate from the reflector.

[0021] According to one variant, the device further includes an outer hood in which are, from the outer hood, the reflector, the diffuser block, the heating element and the cooking plate, the reflector forming a thermal screen between the outer hood and the diffuser block.

[0022] According to one variant, the device also includes a screen between the outer hood and the reflector, the screen and the reflector forming a heat shield between the outer hood and the diffuser block.

[0023] According to one variant, the device comprises: an upper outer hood and a lower outer hood, each outer hood comprising, in the direction of the other hood, a screen, a reflector, a diffuser block, a heating element in the diffuser block and a cooking plate, the cooking plate of each hood being opposite the other cooking plate; a single thermostat associated with the upper outer hood and measuring the temperature of the respective cooking plate or two thermostats, each associated with an outer hood, measuring the temperature of the respective cooking plate.

[0024] According to one variant, the device is capable of concentrating the heat flow by radiation towards the cooking plate, in particular the device is capable of concentrating the heat flow by radiation towards the cooking plate intentionally.

[0025] According to one variant, the device is capable of concentrating the heat flow by conduction towards the cooking plate, in particular the device is capable of concentrating the heat flow by conduction towards the cooking plate intentionally.

[0026] The invention also relates to a method of operation of a household appliance as described above, characterized in that the heating element heats the cooking plate by a double flow of heat by conduction through the diffuser block and by radiation.

[0027] The use, in this document, of the verb "comprendre" (to understand), its variants, and its conjugations, cannot in any way exclude the presence of elements other than those mentioned. The use, in this document, of the indefinite article "un" (a), "une" (an), or the definite article "le" (the), "la" (the), or "l'" (it) to introduce an element does not exclude the presence of multiple such elements.

[0028] The terms "first >>", "second >>, etc. are used in this document exclusively to differentiate different elements, without implying any order between these elements.

[0029] All the preferred embodiments and all the advantages of the household appliance according to the invention are applicable mutatis mutandis to the present method, and vice versa. The different embodiments may be considered individually or in combination. Brief description of the figures

[0030] Other features and advantages of the present invention will become apparent upon reading the detailed description that follows, for understanding of which reference should be made to the accompanying figures which show:

[0031] - Figure 1, an exploded view of all the significant components of a half of a household appliance according to the invention;

[0032] - Figure 2, a schematic cross-sectional view of the household appliance according to the invention;

[0033] - Figure 3 shows an example of the implementation of the diffuser block;

[0034] - Figure 4, a graph of the operation of the household appliance, showing the repetitive and regular cooking cycles.

[0035] The drawings in the figures are not to scale. Similar features are generally denoted by similar reference numerals in the figures. Within the scope of this document, identical or analogous features may bear the same reference numerals. Furthermore, the presence of reference numerals or letters in the drawings shall not be considered limiting, even when such numerals or letters are specified in the claims.

[0036] Detailed description of embodiments of the invention

[0037] The invention relates to a household appliance comprising a heating element for a cooktop and a heat diffuser block positioned against the cooktop. The heating element is both in contact with the diffuser block and separate from and facing the cooktop, the heating element being capable of heating the cooktop by a dual heat flow: conduction through the diffuser block and radiation. This results in more regular and efficient temperature control of the appliance's cooking temperature.

[0038] Figure 1 shows an exploded view of part of a household appliance 50 according to the invention. Figure 2 shows a schematic cross-sectional view of the appliance 50. The appliance 50 comprises two shells as illustrated in Figure 2. In the following description, reference is made to the arrangement of the parts in the upper part of the appliance. The lower part is of identical mechanical and thermal construction, except for the temperature regulation, which is ensured by a thermostat preferably located only in the upper part. Thus, only the electrical connection diagram differs between the upper and lower parts.

[0039] The appliance 50 includes a cooking plate 11 adapted to be in contact with the food to be cooked and a heat diffuser block 10 against the cooking plate 11. The heat diffuser block 10 is in contact with the cooking plate 11. The appliance also includes a heating element 9 arranged within the diffuser block 10. The heating element 9 is, for example, crimped into the diffuser block. The heating element 9 is also opposite the cooking plate 11 and separated from it. The heating element 9 is, for example, separated by a distance of one millimeter. In other words, and as can be seen in Figure 2, the heating element 9 is at a distance from the cooking plate 11: there is a space (or interval, gap) between the cooking plate 11 and the part of the heating element 9 facing the cooking plate 11. The space (or interval, gap) between the cooking plate 11 and the part of the heating element 9 is free.The space (or gap, interstice) between the cooking plate 11 and the portion of the heating element 9 is free of any intervening component. The cooking plate 11 and the heating element 9 are opposite each other, spaced apart. The heating element has a free surface facing the cooking plate. The heating element 9 is not in contact with the cooking plate 11.

[0040] The heating element 9 ensures dual heat transfer. This improves energy transfer, making it more regular and efficient compared to existing appliances, and thus improves the cooking process itself. This dual heat transfer occurs, firstly, by conduction from the heating element 9 to the diffuser block 10, and secondly, by radiation, from the heating element 9 to the cooking plate 11. The heat transfer by conduction takes place from the upper cylindrical surface (or sheath) of the heating element 9, which is in contact with the diffuser block 10, while the heat transfer by radiation takes place from the lower flat surface (or sheath) of the heating element 9, which is directed towards, but away from, the cooking plate 11.As explained below (and particularly thanks to its interaction with a thermostatic system), this dual heat flow ensures a stable and precise heat supply to the entire appliance and an immediate temperature response to the cooking plate, as soon as food is placed on the opposite side of the cooking plate 11. During the heating period, the radiation from the heating element becomes the primary source of intense heat transfer to the cooking plate 11 and is approximately three times more efficient at heat transfer than conduction transfer from the surface of the diffuser block. This arrangement improves the efficiency of the appliance 50, while guaranteeing faster, more even, uniform, and higher-quality cooking of food.Device 50 allows for a faster cooking time compared to the cooking time of existing devices, from the moment the dough is placed on a cavity of the baking plate mold 11, and a sustained cooking rate with equivalent quality.

[0041] The heating element 9 and the diffuser block 10 are independent of the cooking plate 11 and of each other. The heating element 9 and the diffuser block 10 are not mechanically attached to the cooking plate 11. This facilitates appliance maintenance and safer disassembly (particularly electrical) of the cooking plate 11 for maintenance or even replacement, independently of the heating element 9 and the diffuser block 10. Specifically, no electrical connection or disconnection is required to disassemble the cooking plate. This allows the appliance to be disassembled, cleaned, or even repaired independently, in accordance with European and national legislation promoting circular economy practices.

[0042] Figure 3 shows an example of an embodiment of the diffuser block 10. The diffuser block 10 can be in the form of a molded part with a flat face. Figure 3 shows the face of the diffuser block 10 in contact with the cooking plate 11—in particular, the reverse side of the cooking plate 11. The diffuser block 10 is, for example, made of aluminum, which allows for rapid heating. The diffuser block 10 may have a groove 17 (made of aluminum) in the plate, with an opening facing the cooking plate 11. The heating element 9 can be mechanically crimped into the groove 17 of the diffuser block 10. The groove 17 may have a U-shaped cross-section with its opening directed toward the cooking plate 11. The heating element 9 is in direct contact with the groove 17 over a portion of its surface (or circumference).The groove partially surrounds the heating element 9 (being in contact with it), with a portion of the heating element 9's surface facing the cooking plate 11 (without contacting the groove or the cooking plate 11). The heating element 9 is partially enclosed within the groove 17. The portion of the heating element 9's surface not in contact with the groove 17 is set apart and facing the cooking plate 11. The portion of the heating element 9's surface not in contact with the groove 17 does not touch the cooking plate 11. Thus, the heating element 9 is, on the one hand, in contact with the diffuser block (which itself is in contact with the cooking plate 11), and, on the other hand, faces, while remaining separate from, the cooking plate 11. A mechanical crimping ensures that the heating element 9, crimped into the diffuser block 10, is held in place while allowing its dimensional expansion according to its temperature.The arrangement of the heating element 9, embedded in the diffuser block 10 (particularly in the groove 17) and preferably with a flat (or in other words, smoothed or flattened) surface facing the cooking plate 11, allows the radiant heat flow to be directed and concentrated towards the cooking plate 11. Conduction takes place through direct contact between the heating element 9 and the groove of the diffuser block, which is the only part in contact with the cooking plate 11. The diffuser block 10 receives the heat transmitted to it by the heating element 9 by conduction (through contact in the U-shaped groove 17) and transmits it to the cooking plate 11, whose contact surfaces correspond to the active cooking zones.

[0043] The appliance 50 concentrates the dual heat flow towards the cooking plate 11. The appliance 50 is capable of concentrating the radiant heat flow towards the cooking plate 11, particularly due to the positioning of the heating element 9 within the diffuser block 10, specifically in the groove 17 which is open towards the cooking plate 10. The appliance 50 is also capable of concentrating the conductive heat flow towards the cooking plate 11, particularly due to the positioning of the heating element 9 within and in contact with the diffuser block 10, specifically through the groove 17 which partially surrounds the heating element 9 (and is in contact with the heating element 9). This results in reduced heat loss throughout the appliance 50.Device 50 prevents unintentional heat flow by radiation and / or conduction, prevents heat loss by radiation and / or conduction, and prevents diffuse heat flow by radiation and / or conduction. Thus, the concentration of heat flow is intentionally and deliberately focused within device 50, as components are provided for this purpose (in particular, the diffuser block 10 and the groove 17).

[0044] The heating element 9 can be a heating tube. For example, the heating element 9 can be a tube made of SUS321 containing a Kanthal heating wire (registered trademark) and magnesium oxide powder insulation. This element is an integral part of the dual-flow heat diffuser. It has a dual configuration: a cylindrical surface and a flattened surface (or face). In other words, the heating element can be a metal tube, the upper part of which has a cylindrical (outer) surface (with a circular cross-section) and the lower part has a flattened (outer) surface, or flat 52. The flattened (outer) surface, or flat 52, is positioned away from and facing the cooking plate. The lower part of the heating element can be flattened to a width of approximately 5 millimeters along its entire length.The heating element is thus, on the one hand, in contact with the U-shaped groove 17 of the diffuser block 10 over more than 50% of the cylindrical surface of the tube-shaped heating element and, on the other hand, thanks to its particular partially flattened shape, faces directly with - while being at a distance (for example, of a little less than one millimeter) from - the cooking plate 11. The flat 52 allows the heating element 9 to be positioned close to the cooking plate 11. The heating element 9 transmits heat both by conduction towards the diffuser block 10 (in particular from its cylindrical part) and by radiation towards the cooking plate 11 (in particular from its flattened surface).The appliance's design ensures near-instantaneous interaction between the cooking plate 11 and the diffuser block 10, resulting in faster, more even cooking and a much more immediate temperature response time than existing appliances, as well as improved temperature control of the diffuser block 11 (and therefore indirectly of the cooking plate 11). As described later, a thermostatic system within the appliance (itself composed of the thermal link bulb 13 and the thermostat 12) further enhances these advantages.

[0045] The appliance 50 may have a single cooking plate 11. The entire appliance 50 may have two cooking plates 11 facing each other to enclose the food during cooking. The appliance 50 may remain open and cook foods such as pancakes. Preferably, the cooking plates 11 are removable, allowing for easy cleaning and / or replacement with other plates suitable for different types of food. For example, the appliance 50 allows the use of different plates shaped like waffles, toasted sandwiches, ice cream cones, wafers, grill plates, teppanyaki plates, or planchas, etc. Eight or more different types of plates are possible. The plates are easily interchangeable using a simple tool (coin, etc.).The heating response of the plates is very efficient, even though the plates are removable, unlike existing appliances where a rapid heating response can be achieved by integrating the heating element into the cooking plate, for example, by overmolding it. This can make the heating element dependent on the cooking plate and require the cooking plates to be fixed within the appliance, complicating cleaning of the cooking area and making the cooking plates non-interchangeable. Furthermore, the invention can be adapted to existing appliances. The dimensions of the appliance are not modified, and it is not necessary to modify the existing cooking plates, which can therefore be used in the appliance according to the invention.

[0046] The plates, made of die-cast or cast aluminum, provide a significant energy reservoir, resulting in optimal cooking performance. The plates can be coated with a non-stick layer on the surface in contact with food to prevent sticking during cooking. The cooking plates can accommodate foods that are already solid (such as toasted sandwiches) or that will be shaped during cooking (such as dough balls or waffle batter). Furthermore, the perimeter of the plates absorbs any excess food during cooking. For example, the waffle plates feature a wide perimeter of molds to absorb any excess batter, preventing it from overflowing.

[0047] The entire appliance 50 comprises outer covers, specifically an upper outer cover 3 and a lower outer cover 3. The material of the outer covers 3 is, for example, phenol PF2A. The outer covers 3 define the upper and lower shells or parts. Starting from an outer cover, the following components are arranged in order: the diffuser block 10, the heating element 9, and the cooking plate 11. When the shells are stacked, the cooking plates 11 face each other, and the outer covers 3 form the exterior (or wall) of the appliance 50. The entire appliance 50 can rest on the outer cover.

[0048] 3 lower during cooking. The outer cover 3 prevents users from coming into contact with the heated parts.

[0049] The appliance 50 also includes a heat reflector 8, with the diffuser block 10 arranged between the cooking plate 11 and the heat reflector 8. The heat reflector 8 sits atop the diffuser 10 and protects an intermediate screen.

[0050] 4, which itself acts as a thermal shield to limit the contact temperatures of the upper cover 3. The reflector 8 forms a thermal shield between the outer cover 3 and the diffuser block 10. In other words, the reflector 8 constitutes a thermal shield between the area where the diffuser block 10 is located and the upper area of ​​the screen 4 (described hereafter) of the device 50. This ensures control of the heating temperatures of the entire device. Thanks to the reflector covering the diffuser block 10 and the presence of the screen 4, the heating of the outer covers 3, the thermostat knobs, and the handles of the device (and more generally, the outer wall of the device) is reduced below safe values. The reflector 8 can be a metallic reflector, made of double-sided aluminized rolled steel. It can also be a stamped sheet.This can be a stamped, aluminized steel sheet with a shape that rests peripherally on the cooking plate 11. The metallic reflector 8 can be coated with a layer of aluminum. This coating reflects some of the heat emitted by the reflector back onto the cooking plate.

[0051] The device 50 also includes a screen 4. The material of the middle screen 4 is, for example, phenol PF2A. The screen 4 is located between the outer cover 3 and the reflector 8. The screen 4 and the reflector 8, forming a thermal shield, are located between the outer cover 3 and the diffuser block 10. The screen 4 reinforces the thermal shield formed by the reflector 8, creating a thermal shield that protects the outer cover 3 from radiation emitted by the diffuser block 10. This ensures that the temperature of the user-accessible parts of the device remains below the limits imposed by safety standards, particularly European ones.

[0052] According to Figures 1 and 2, the appliance 50 includes compression springs 5 ​​that hold the diffuser block 10 against the cooking plate 11. These compression springs 5 ​​ensure that the diffuser block 10 maintains contact with the cooking plate 11. This contact is particularly optimal and consistent. The heat diffuser is mobile, and the mobility of the dual-flow heat diffuser, driven by the springs, guarantees perfect thermal contact between the diffuser block and the cooking plate. The simultaneous pressure of the springs 5 ​​promotes direct heat transfer between the diffuser block 10 and the heating element 9, and between the diffuser block 11 and the cooking plate 11. These springs thus allow the heat energy, transferred by conduction, to be concentrated directly on the cooking plates 11, while limiting any energy loss, which is then only indirect, to the walls and internal peripheral components of the appliance 50.The number of springs 5 ​​is chosen to ensure good contact between the diffuser block 10 and the cooking plate 11. There may be two, three, or more springs, preferably four, as shown in the diagrams. This allows for a distributed force to be applied to the diffuser block 10. Each spring 5 exerts force on a guide column 7 against the diffuser block 10. The guide columns 7 transmit the force from the springs 5 ​​to the diffuser block 10 via the reflector 8. Each spring 5 exerts force on a guide column 7 via a spacer 6, preferably made of ceramic. The spacers 6 provide the mechanical connection between the springs 5 ​​and the guide columns 7 of the diffuser block 10. The insulating spacers 6 protect the compression springs 5 ​​from any heat transfer that would eventually reduce their compressive strength.

[0053] The springs 5 ​​can be calculated to generate a pressure of approximately ±10 N under a compression of 5 mm. The springs 5 ​​can be made of SUS304 stainless steel. This stroke is adjusted by the length of the cylinder of the guide columns 7. The travel is limited by the heads of the guide columns 7, which come against the reflector 8, particularly when changing the cooking plate 11. The outer covers 3 can have recesses 20 that serve as seats for the pressure springs 5 ​​of the diffuser block 10. For example, there are four recesses 20. The guide columns 7 hold the diffuser 10 and the heating element 9 in place.

[0054] The guide columns 7 (free-cutting steel) have a shoulder 26 and are screwed into the diffuser block 10 to limit its movement. When the cooking plates 11 are placed on the appliance 50, the diffuser block 10 compresses the springs 5, which transmit and apply pressure from the diffuser 10 to the cooking plate 11, for example, approximately ±10 N. The pressure thus applied ensures that all these components of the appliance are held firmly in place throughout the cooking time, thereby transferring heat from the heating element 9 by radiation from its free surface directly to the cooking plate 11 and by conduction to the diffuser block 10 (and thus indirectly to the cooking plate 11), thereby ensuring an optimal temperature level.

[0055] The appliance is equipped with a thermostat 12. The thermostat 12 regulates the temperature according to the position of a thermostat knob operated by the user, depending on the type of food being cooked. This allows for control of the temperature rise of the cooking plate 11 and optimal regulation of its temperature during the cooking time. The thermostat 12 is, for example, a bimetallic variable thermostat, consisting of a steel frame, a rotating brass shaft, and a bimetallic steel blade that, depending on the temperature, opens or closes the snap-action switch contacts.

[0056] The thermostat 12 includes a thermal connection bulb 13. The thermal connection bulb 13 may be made of aluminum. It may be mechanically attached to the thermostat 12. It is positioned against the rear area of ​​the bimetallic strip. The bulb 13 may have a central recess 18 and is protected from the heat diffuser block 10 by the reflector 8 by means of a central indentation. The bulb 13 may also be equipped with a shoulder. Thanks to its positioning, the device allows the thermal connection bulb 13 to offer several advantages. The position of the thermal connection bulb ensures optimum heat transfer and temperature balance between the cooking plate 11 and the thermostat 12, which actuates the opening and closing of the thermostat switch contacts. The central recess 18 of the bulb 13 allows for greater sensitivity in monitoring temperature variations of the cooking plate 11 in its central zone 16.Thanks to its shoulder, the bulb 13 limits its travel as soon as it comes into contact with the reflector 8 when the cooking plate 11 is changed or cleaned.

[0057] A zone 21 is reserved in the center of the diffuser block 10, allowing passage for the thermostat and its mechanism, including the bulb 13. Thus, the diffuser block 10 does not radiate heat directly onto the bimetallic strip of the thermostat 12 or onto its bulb 13, which is partially protected by the reflector 8. The thermostat 12, via its bulb 18 and its bimetallic strip, extends through zone 21 within the diffuser block 10, whose heat does not interact, even by radiation, with the thermal regulation of the thermostat and the cooktop 11. Zone 21 can be enclosed by the diffuser block 10, as shown in Figure 3, or it can be an open passage. Zone 21 is centrally located within the diffuser block 10 so as to control the temperature at the center of the cooktop 11. This allows the temperature of the cooking plate 11 to be controlled in a position where heat loss to the outside of the appliance 50 is lowest.

[0058] The thermostat 12 can be positioned and slid along a shaft 15 which is mechanically fixed in the outer cover 3. The shaft 15 supporting the thermostat 12 can be metallic. The shaft 15 ensures the correct positioning of the thermostat 12 within the appliance to guarantee proper temperature control of the cooking plates – and therefore, of the cooking process. A spring 14 (for example, made of spring steel) can be placed on the shaft 15 and applies pressure to the thermostat bulb against the cooking plate. The spring 14 applies continuous pressure to the thermostat 12, which is mounted on top of it. This assembly constitutes the thermostatic system. When the cooking plate 11 is attached to the device 50, the bulb 13 is put under pressure against the cooking plate 11, in particular against a central area 16 of the plate, by means of the spring 14. This pressure ensures a similarity of temperatures of the bulb and the plate 11 and thus ensures proper thermal regulation of the cooking plate 11.Furthermore, when the cooking plate 11 is removed for replacement or cleaning, the bulb 13 of the thermostat 12 is fitted with a shoulder 19 which limits its travel as soon as it comes into contact with the reflector 8.

[0059] Thermostat 12 allows for precise temperature control of appliance 50. The overall thermostatic system design offers several advantages, including optimal heat output responsiveness to any temperature difference on the cooking plate 11, reduced cooking time, and thus superior performance compared to existing appliances. Furthermore, the central embossed section of the metal reflector protects the bulb 13 of thermostat 12 from any heat that the diffuser block 10 might transmit through direct radiation. This ensures that heating temperatures comply with current European and international standards.

[0060] The thermostatic system, composed of the regulating thermostat 12 and the bulb 13 (and the other parts described above), interacts with the diffuser block 10 and the heating element 9 (these last two elements forming the dual-flow thermal diffuser). The arrangement of these elements and their specific shape (as described below) ensure precise heat transfer from the cooking plate 11 to the bimetallic element of the thermostat. The bulb 13, mounted on the regulating thermostat 12, is designed as a ring with a diameter substantially identical to the diameter of the central zone 16 of the cooking plate 11. This ring (the lower base of the bulb 13) is hollow in its center 18 and is in direct contact with the central zone 16 of the cooking plate 11, while the upper part of the bulb is closed to ensure direct contact with the bimetallic element of the thermostat 12.The bulb 13 and the bimetal of the thermostat 12 are thermally protected from any direct influence of the double flow thermal diffuser by the central stamping of the metal reflector 8 which caps the diffuser block 10.

[0061] This arrangement of the entire thermostatic system prevents the double flow thermal diffuser from transmitting heat by radiation onto the bimetal of the thermostat 12 or onto its bulb 13. The temperature regulation of the appliance is thus more precise and regular and improves the responsiveness of the thermostat, which is therefore directly and essentially linked to the thermal variations of the cooking plate 11 alone.

[0062] The appliance 50 may also include a control knob 1. Knob 1 allows for ON / OFF operation as well as temperature control. It allows the user to select the desired temperature level for the cooking surface according to the consumer's preferences and the food being cooked. A graduated scale is present on a ring surrounding knob 1, providing the user with a reference point for their chosen cooking temperature. This selection, of course, remains within the operating temperature range calibrated by the thermostat's specifications. The control knob 1 may be made of PA66. An insulating spacer 2 (for example, made of PPS) is positioned between the axis of the thermostat 12 and the control knob 1. The spacer 2 acts as an intermediary piece, reducing the heat generated by knob 1.

[0063] The invention also relates to a method of operating the household appliance. Figure 4 shows a graph of the operation of the appliance 50. The graph shows the temperature (ordinate) as a function of time (abscissa) of the diffuser block 10 (upper and lower, curves 40a and 40b), the cooking plate 11 (curve 42), and the bulb 13 (curve 44). In Figure 4, the reference numerals 481, 482, 483, 484, and 485 are respectively the first, second, ..., fifth cooking times after loading food (the first cooking time 481 serving to thermally stabilize the appliance). The reference numeral 54 designates a time for unloading and loading food onto the cooking plate 11, approximately 30 seconds, for example. The loaded food might be, for example, two dough balls of 110 grams each. Line 46 indicates the average temperature of hob 11, while line 42 indicates the temperature variations of hob 11.

[0064] The appliance allows for precise temperature regulation. The dual-flow thermal diffuser (comprising the diffuser block 10 and the heating element 9), thanks in particular to its interaction with the thermostatic system (comprising in particular the thermostat 12 and the bulb 13), allows for better temperature management and thus a reactive heating of the cooking plate 11 upon contact with food, faster and more balanced cooking, and a reduction in cooking time by the appliance 50.

[0065] The appliance is responsive for the following reasons. When food is placed on the cooking plate, its temperature drops. However, thanks to the bulb 13 of the thermostat 12, which immediately detects this temperature decrease, the thermostat 12 closes its contacts (i.e., switches to "ON") shortly after the food is placed on it, thus allowing the heating element 9 to generate heat. Once this heat is transferred by conduction to the diffuser block, the temperature of the latter is transferred to the cooking plate (as indicated by lines 42 and 40a in Figure 4). Simultaneously, the temperature of the cooking plate 1 also increases due to the radiation from the heating element 9, whose temperature is much higher than that of the diffuser block.It is therefore the simultaneous interaction between the thermostatic system and the dual-flow thermal diffuser that ensures, on the one hand, the simultaneous increase in the temperature of the diffuser block 10 and the cooking plate 11 (and the food) and thus, on the other hand, the responsiveness of the appliance (unlike existing appliances). Curves 40a and 42 in Figure 4 confirm this observation.

[0066] Line 46 in Figure 4 represents the average temperature of the cooktop. Line 42 in Figure 4 illustrates the variation in cooktop temperature during cooking. In this same figure, reference 55 shows a double arrow indicating the thermostat switching to "ON" at the beginning and "OFF" at the end. Reference 55 indicates the heating time. The double arrow 55 represents a duration of 1 minute 30 seconds. We observe that 1 minute 30 seconds after switching to "ON," the thermostat systematically switches to "OFF." The heating time (and therefore the electricity consumption time) is thus only 1 minute 30 seconds, while the cooking time itself is 2 minutes 30 seconds, which is much shorter than the cooking time of existing appliances, which can reach up to 6 minutes (see the table below).The 1 minute 30 second heating period begins following the temperature drop caused by adding food to the cooktop. Although the heating element is powered from the start of the heating period (the thermostat is set to "ON"), the cooktop temperature continues to decrease due to its thermal inertia for only a few seconds to reach its minimum point of 165°C (on average), as indicated on line 42; this is essential for thoroughly cooking the food. However, the temperature drop is controlled and shorter than that of existing appliances (the minimum temperature of other existing appliances can be as low as 120°C). It rises quickly thanks to the dual-flow system, which allows the thermostat to automatically shut off the heating after 1 minute 30 seconds.After the heating stops (the thermostat is on "OFF >>"), the temperature of the cooking plate continues to increase but without the expenditure of electrical energy due once again to the thermal inertia of the plate until its peak (at approximately 213°C) which may correspond to the moment of pause of new food, as indicated by line 42 of figure 4.

[0067] The temperature curves in Figure 4 confirm that the temperature variation of the cooking plate 11 is synchronized with the thermal variations of the diffuser block at the start of the heating cycles. These curves clearly show the almost simultaneous response of the temperature curves of the cooking plate 11 (curve 42) and the temperature of the diffuser block 10 (curves 40a). Unlike the performance of existing appliances, there is practically no difference between the moment when the heating element 9 resumes heating after the thermostat is switched to the "ON" position and the temperature rise of the cooking plate 11, whose temperature had dropped after food was added.This therefore makes it possible, on the one hand, to avoid a long and significant drop in temperature when adding food / dough to the cooking plate which can be seen on existing appliances and thus, on the other hand, if food is added after each cooking, to guarantee a quick and even cooking.

[0068] The appliance ensures rapid and even cooking for the following reasons. As soon as the food / dough is placed on the cooking plate 11, it will experience a temperature drop due to the "cold" food (such as waffle batter). The high energy capacity of the aluminum mass of the cooking plate 11 ensures excellent and continuous heat transfer to the dough. In this design, the large volume of aluminum in the cooking plate 11 provides an energy reserve for rapid and even cooking of the food across its entire surface. Between the moment the food / dough is placed on the plate (peaks of curves 42 and 44) ​​and the thermostat's "switch on" point, the heat accumulated in the plates provides the initial heating, and then the heat from the diffusers allows curves 42 and 44 to return to their normal temperature.

[0069] The appliance reduces cooking time for the following reasons. As mentioned above and as can be seen in Figure 2, the combination of the diffuser block and the thermostatic system ensures a faster temperature maintenance response within a narrower timeframe. This results in high-quality baking with a time saving of over 50% compared to the 6 minutes required to bake two 110g dough balls on existing appliances. The 50 appliance, on the other hand, requires approximately 2 minutes and 30 seconds to bake two 110g dough balls. Thus, cooking time is reduced, and thanks to the appliance's responsiveness, each new dough ball / food item can be baked immediately afterward with the same level of quality and speed.

[0070] The table below (showing the average baking time of two 110g dough balls as an example) confirms that the baking time of these 110g dough balls on appliance 50, equipped with the dual-flow heat diffuser (which can be 1400W), is reduced by up to 50% or more compared to the baking time on existing appliances. The power level of the dual-flow heat diffuser is between 1000W and 1400W. This lower power level than prior art results in a shorter baking time.

[0071] Table 1

[0072] The 50 appliance ensures optimal energy consumption. In addition to a (substantially) reduced cooking time, regardless of the type of food in contact with the cooking plates (11) or the desired cooking frequency (i.e., whether continuous or spaced out), the dual-flow heat diffuser can be installed on an appliance with a power rating of 1,400 watts while guaranteeing optimal cooking quality (i.e., in a waffle iron, for example, the browned surface of the waffles is uniform). The same is true for an appliance with a power rating of 1,200 or even 1,000 watts, although in the latter case, the cooking time is slightly longer than for an appliance with a power rating of 1,400 watts.

[0073] The use of the dual-flow heat diffuser also offers several advantages compared to existing, higher-power appliances (1600W). Firstly, it allows for reduced energy consumption, thereby reducing the environmental impact of appliances equipped with the dual-flow heat diffuser. Aside from the reduced cooking time (which logically leads to lower energy consumption), it has been observed that the electricity consumption of the appliance, such as a waffle maker, is reduced by more than 20% when cooking 20 Liège waffles compared to existing, more powerful appliances (1600W). Furthermore, the lower power consumption avoids the need to use excessively high power (1600 watts), which regularly results in overcooking of food (such as waffles or toasted sandwiches), potentially leaving the outer surfaces burnt and the center undercooked.

[0074] Finally, with the 50 model, the user retains the option of a lower cooking temperature while ensuring a flavor profile tailored to individual tastes, thanks to the adjustable thermostat installed on the model equipped with a dual-flow heat diffuser. It is clear from the above that the use of the dual-flow heat diffuser allows for a substantial reduction in the energy consumption of cooking appliances while ensuring optimal cooking, which aligns perfectly with overall energy policy and benefits users.

[0075] In existing appliances, the heating element can reach a temperature of 700°C and distribute its heat in all directions throughout the entire appliance. As a result, it heats not only the reflector but also the rest of the appliance. Conversely, in appliance 50, thanks to the dual-flow heat diffuser (and in particular the thermostatic system), the heating element 9 transmits part of its temperature by conduction to the diffuser block 10. Thus, the temperature of the diffuser block 10 is limited to slightly more than half that of the heating element 9, while the heating element 9 radiates its temperature of 600°C directly to the cooking plate 11, whose temperature therefore fluctuates much more rapidly. This dual flow significantly reduces energy losses throughout the appliance and ensures rapid cooking response.

[0076] The device 50 reduces the temperature of the diffuser block 10. The heating element 9 transfers some of its temperature to the diffuser block 10 by conduction. Thus, even if the temperature of the heating element 9 reaches 600°C, the temperature of the diffuser block 10, with the thermostat 12 in its maximum position, only reaches a peak of 314°C, with an average temperature of 281°C, and the temperature of the cooking plate 11 only reaches a peak of 213°C, with an average temperature of 188°C (see Figure 4). The user can adjust the temperature of the device according to their needs using the variable thermostat, but the described thermal efficiency can be observed for all thermostat positions.

[0077] This temperature stabilization in turn allows balanced, constant and efficient cooking for all thermostat positions, while only moderately radiating heat onto the construction components of the appliance 50, which is not possible in existing appliances.

[0078] The appliance 50 reduces the temperature of the other components. Equipped with the dual-flow heat diffuser and thermostatic system, the appliance 50 offers another advantage: reducing the temperature of the other components. Specifically, reducing the temperature of the diffuser block 10 allows for better control and management of the contact temperature values ​​on the outer casing 3 and the screen 4 of the appliance. Furthermore, the diffuser block 10 is separate from the reflector 8. The diffuser block 10 is not in contact with the reflector 8, but only with the cooking plate 11. This also significantly limits the temperature rise of the external surfaces of the appliance, which the reflector separates from the dual-flow heat diffuser and the cooking plate.Finally, reducing the temperature of the other components of the appliance is also facilitated by the fact that the dual-flow heat diffuser is mounted on several compression springs 5 ​​(four, for example) which ensure a contact pressure of 10 N between the diffuser block 10 and the cooking plate 11. The heat energy is thus concentrated directly on the cooking plate 11 and, to a lesser extent, indirectly on the walls and internal peripheral components of the appliance. Unlike appliance 50, the heating element of some existing appliances can be positioned in a wide recess of a reflector and radiates heat into an area between this reflector and the cooking plate. This type of construction results in heat diffusion in all directions, even though the surface temperature of the heating element is very high, potentially approaching 700°C.This leads to unintentional heating of the internal peripheral components of the appliance, which the invention prevents. Appliance 50 simplifies the removal of the cooking plate and the electrical connection. In existing appliances, the heating element is integrated into the aluminum cooking plate, for example, by overmolding. This system has certain drawbacks. Either the cooking plate must be fixed, in which case cleaning the cooking area is complicated, or, if the cooking plate is removable, heat-resistant seals must be added to ensure the heating element is watertight, which makes the electrical connection of the heating element terminals more complex. The invention avoids these drawbacks.

[0079] The appliance is, for example, a waffle maker or a sandwich maker – or something else depending on the type of cooking plates used, as indicated above. The description above refers to one half of the appliance – for example, half a waffle maker. However, the other half of the appliance, for example, the lower part or casing, is of identical mechanical and thermal construction to the upper part or casing, but the temperature control is provided by the thermostat located in the upper part.Thus, the appliance 50 comprises an upper outer cover 3 and a lower outer cover 3, each outer cover 3 comprising, facing the other cover, a screen 4, a reflector 8, a diffuser block 10, a heating element 9 within the diffuser block, and a cooking plate 11, the cooking plate of each cover being opposite the other cooking plate. The appliance further comprises a single thermostat 12 associated with the upper outer cover and measuring the temperature of the respective cooking plate, or two thermostats, each associated with an outer cover, measuring the temperature of the respective cooking plate. It is therefore conceivable that the appliance 50 could be equipped with a thermostat in each part of the appliance. Only the electrical connection diagram differs. The upper cover 3 with the passage for the thermostat 12 is used for the lower part instead of the fully closed lower cover as shown in Figure 2.The two parts or shells can be hinged to each other, for example, by folding the upper part over the lower part for cooking. The present invention has been described in relation to specific embodiments, which are purely illustrative and should not be considered limiting. Generally speaking, it will be obvious to a person skilled in the art that the present invention is not limited to the examples illustrated and / or described above.

Claims

24 Demands 1. Household appliance (50) comprising: - a cooking plate (1 1 ), - a heating element (9) of the cooking plate (11), - a heat diffuser block (10) against the cooking plate (11) characterized in that the heating element (9) is both in contact with the diffuser block (10) and away from and facing the cooking plate, the heating element (9) being capable of heating the cooking plate (11) by a double flow of heat by conduction through the diffuser block (10) and by radiation.

2. Household appliance (50) according to the preceding claim, in which the heating element (9) has a surface partly cylindrical and partly flattened, the partly cylindrical surface being in contact with the diffuser block (10) and the flattened surface being away from and facing the cooking plate (11).

3. Household appliance (50) according to any one of the preceding claims, wherein the heating element (9) and the diffuser block (10) are independent of the cooking plate (11).

4. Household appliance (50) according to any one of the preceding claims, wherein the diffuser block (10) has a groove (17) with an opening in the direction of the cooking plate (11), the heating element (9) being in the groove and away from and facing the cooking plate through the opening of the groove.

5. Household appliance (50) according to any one of the preceding claims, further comprising compression springs (5) for the diffuser block (10) against the cooking plate (11).

6. Household appliance (50) according to the preceding claim, wherein the compression springs (5) ensure that the diffuser block (10) has optimal and systematic contact with the cooking plate (11).

7. Household appliance (50) according to one of the two preceding claims, wherein the diffuser block (10) and the heating element (9) are movable, the stress by the compression springs (5) ensuring the thermal contact of the diffuser block (10) against the cooking plate.

8. Household appliance (50) according to any one of the preceding claims, further comprising a thermostat (12) regulating the temperature of the cooking plate, the thermostat extending through a passage zone (21) in the diffuser block (10).

9. Household appliance (50) according to the preceding claim, in which the thermostat (12) comprises a bulb (13), the bulb being in pressure against the cooking plate (11).

10. Apparatus (50) according to the preceding claim, comprising a shaft (15) on which the thermostat (12) is placed and a spring (14) urging the thermostat (12) towards the cooking plate, the bulb (13) being put under pressure against a central zone (16) of the cooking plate (11).

11. Apparatus (50) according to one of the two preceding claims, wherein a lower part of the bulb (13) is a ring surrounding a central recess (18) and an upper part of the bulb (13) is closed to have contact with a bimetal of the thermostat, the bulb and the bimetal being thermally protected from the heating element (9) and the diffuser block (10).

12. Household appliance (50) according to any one of the preceding claims, in which the cooking plate(s) (1 1 ) are removable.

13. Apparatus (50) according to any one of the preceding claims, further comprising a heat reflector (8), the diffuser block (10) being arranged between the cooking plate (11) and the reflector (8).

14. Apparatus (50) according to the preceding claim, in which the diffuser block (10) is separated from the reflector (8).

15. Apparatus (50) according to one of the two preceding claims, further comprising an outer hood (3) in which are, from the outer hood, the reflector (8), the diffuser block (10), the heating element (9) and the cooking plate (11), the reflector (8) forming a thermal screen between the outer hood (3) and the diffuser block (10).

16. Apparatus (50) according to the preceding claim, further comprising a screen (4) between the outer hood (3) and the reflector (8), the screen and the reflector forming a heat shield between the outer hood (3) and the diffuser block (10).

17. Household appliance (50) according to any one of the preceding claims, comprising: - an upper outer hood (3) and a lower outer hood, each outer hood comprising, in the direction of the other hood, a screen (4), a reflector (8), a diffuser block (10), a heating element (9) in the diffuser block and a cooking plate (11), the cooking plate of each hood being opposite the other cooking plate; - a single thermostat (12) associated with the upper outer cover (3) and measuring the temperature of the respective cooking plate or two 27 thermostats (12), each associated with an outer cover (3), measuring the temperature of the respective cooking plate.

18. Household appliance (50) according to any one of the preceding claims, the appliance (50) being capable of concentrating the heat flow by radiation towards the cooking plate (11), in particular the appliance (50) being capable of concentrating the heat flow by radiation towards the cooking plate (11) in a voluntary manner.

19. Appliance (50) according to any one of the preceding claims, the appliance (50) being capable of concentrating the heat flow by conduction towards the cooking plate (11), in particular the appliance (50) is capable of concentrating the heat flow by conduction towards the cooking plate (11) in a voluntary manner.

20. Method of operating a household appliance according to one of the preceding claims, characterized in that the heating element (9) heats the cooking plate (11) by a double flow of heat by conduction through the diffuser block (10) and by radiation.

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