ES2562705T3 - Heating system - Google Patents

Abstract

A heating system, comprising: a box-shaped heating chamber (10); a heater (20) provided inside said heating chamber (10), wherein said heater (20) is made of a conductive material in an electrical loop; a coil (30) provided outside said heating chamber (10); a power circuit for supplying high frequency current with said coil (30) to generate a high frequency magnetic flux; characterized by a magnetic member (34) arranged such that said heater (20) magnetically interconnects with high frequency magnetic flux generated by said coil (30), wherein said magnetic member (34) has an opening (36) , in which a part (24) of said heater (20) is inserted.

Description

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DESCRIPTION

Heating system Technical field

The present invention relates to a heating system and, in particular, refers to a heating cooker that incorporates an induction current heater as a heat source in a heating box, such as a heating oven, a toaster And a grill.

Background of the technique

Many of the heating cookers that apply an electromagnetic induction heating principle, known as CI (induction heating) cookers, include a heating box for cooking grilled fish, etc. The heating box is generally called the heating oven, toaster or grill. A grilled fish (especially a common flash roasted with salt, etc.) is very popular when its surface is browned by the heat of radiation from a heat source and its interior is well heated in a hot atmosphere.

When cooking grilled fish, such as the common grilled fish, a substantial amount of fat (combustible oil) is released from the grilled fish. Therefore, it is necessary to provide a source to receive the fat, and to keep the source and the fish fat in it at a temperature below the ignition temperature thereof to prevent the fish fat from burning in the inside the heating box during cooking. This is not limited to grilled fish, meat cooking is also fulfilled. Said cooked is also called grilled.

The heating box of the CI kitchen heater is typically provided with upper and lower electric heaters such as insulating cover heaters and radiant heaters, which can also be referred to as "resistive heaters", since they generate heat by Joule effect when a current flows through of resistive elements. Electric heaters receive energy through terminals electrically connected to a power supply that is positioned outside the heating box, thereby generating heat by Joule effect when electric power is supplied from the power supply. Electric heaters that receive electric energy convert electric energy into thermal energy that heats and grills the food to be cooked inside the heating box directly and / or indirectly through the heated atmosphere around the food. Said heating cooker is incorporated not only into the IC cookers but also into a toaster oven and an electric oven. Although the heating stove has a simple structure, the interior of the heating box is difficult to clean since the electric heaters are fixed inside the heating box and, therefore, it is necessary to improve the structure of the heating kitchen so that they are cleaned more easily. Thus, in any type of heating system that includes not only CI kitchens, but also heating ovens, the easy cleaning feature is in high demand, and is an essential requirement for food kitchens. In fact, to date many heating furnaces have been proposed which have the metal heating source for food that can be arranged inside the contactless or induction heating box, and / or separated from the heating box.

For example, as described in patent document 1 (JP 2003-282221 A), a conventional furnace using the induction heating technique includes upper and lower heating coils provided above and below the heating box made in magnetic material, and heats the heating box by supplying high frequency current through the heating coils. The heating box can be separated from the oven, so that cleaning is facilitated. See patent document 1, paragraphs [0008] - [0009] and Fig. 2.

In addition, according to another microwave oven using induction heating technique as suggested in patent document 2 (JP 08-138864 A), a heat-resistant insulating separator, of heat-resistant glass, is used to separate mechanics and electrically a heating coil by induction of the heating chamber, and a heated metal body is provided within the heating chamber on the separator, opposite to the heating coil. The heated body is formed as a metal band in a closed loop and, therefore, can be designed to effectively generate an induction current, and an area for arbitrarily adjusted heat radiation. The body is also structured so that it is removably disposed within the heating chamber. See patent document 2, paragraphs [0024] - [0028] and Figs. 1, 3.

Another additional microwave oven using the induction heating technique as suggested in patent document 3 (JP 06-18044 A) includes induction heating means for the peripheral parts of induction heating (or left and right parts) from an oven source that is removably installed within

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The oven chamber. The oven source includes a plate made of a magnetic material such as an iron plate that has an enameled part at least where the oven source is heated. Induction heating means include a coil wound as a coil used in a sewing machine, and a core to effectively provide the magnetic flux generated by the coil with the oven source. The core has, for example, a U-shape, and the high-frequency magnetic flux forms a closed magnetic path through the core and the peripheral part of the furnace source, instead of the other parts of the microwave oven. The oven source is structured so that it has a lower part of magnetic material such as magnetic stainless steel and an upper part of highly thermally conductive material, such as aluminum and copper. The magnetic material is heated by induction by the magnetic flux through the coil and the core, whose heat is finally propagated to the furnace source of highly thermally conductive material. See patent document 3, paragraphs [0022], [0029] - [0036], and Figs. 1, 2, 5-7.

Summary of the invention

Problems to be solved by the invention

When the heating box or chamber using the conventional induction heating techniques indicated above is adapted to the CI kitchen heaters for grilling, a couple of problems have arisen below. In the conventional furnace described in patent document 1, a U-shaped magnetic body is inserted into the heating box and is heated by the induction current through the upper and lower heating coils and, therefore , the lower surface of the magnetic body should be kept at a temperature below the ignition temperature (approximately 250 degrees C) of the fat in food (for example, fish fat). In this way, because the lower surface of the magnetic body cannot be heated sufficiently, there is a problem in the sense that the oven is not suitable for grilling by means of radiation.

In the conventional microwave oven described in patent document 2, because the metal band is formed in a closed loop, effective induction heating at a high temperature is achieved. However, when the heat of the infrared radiation from the metal band is used for cooking on the grill, the fat receiver separator must be provided between the metal band and the heating coil. It should be designed so that the magnetic flux passes through the metal strip to be heated but not through the fat receptor separator. Thus, it is necessary that the fat receptor separator be made of an insulating material, such as ceramic. However, the ceramic separator should be thick enough to ensure mechanical strength, and it should also be sufficiently far from the metal band to keep the temperature of the separator below the ignition point of the grease to prevent the grease in the separator from burn In this way, it is necessary to maintain a substantial gap or distance between the metal band and the fat receiver separator, which poses another problem in the sense that the metal band cannot be efficiently heated by the heating coil.

On the other hand, the microwave oven described in patent document 3 can be used with the oven source for cooking with a pan, but it is not suitable for grill cooking although the oven source can possibly be heated to generate heat by radiation to grill. However, the microwave oven heating coils suggested by patent document 3 can only heat the peripheral parts of the oven source and, in this way, the center or the central part thereof is barely indirectly heated by heat. transferred from the peripheral parts of the furnace source, which is made of a material of high thermal conductivity, such as aluminum and copper, Therefore, it is necessary to make the highly conductive thermal material quite thick in order to sufficiently heat the part central of the oven source. This causes inconveniences, in turn, such as the reduction of the space of the heating chamber and the increase in the heat capacity of the furnace source which requires a substantial time to heat the furnace source.

The present invention addresses the drawbacks indicated above and has the purpose of carrying out a heating system that improves the ease of cleaning characteristics of the heating chamber with removable heaters, and eliminates the problem of food grease by means of the provision of means of induction heating to heat the heaters outside the side walls of the heating chamber, also achieving a substantially high overall temperature in the heating chamber.

Means to solve the problems

In order to overcome the drawbacks described above, an embodiment of the present invention is to provide a heating system of the present invention comprising a box-shaped heating chamber, a heater provided within the heating chamber, in which the heater is made of conductive material in an electric loop, a coil provided outside the heating chamber, a power circuit to supply high frequency current with the coil to generate a high frequency magnetic flux, and a magnetic member arranged to so that the heater is magnetically interconnected with the magnetic flux of

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High frequency generated by the coil.

Advantage of the invention

An embodiment of the heating system according to the present invention generates induction current through a heater made of conductive material in an electric loop, which generates heat by Joule effect by means of the induction current along the heater.

Brief description of the drawings

Fig. 1 is a cross-sectional view of the heating cooker according to the first embodiment of the present invention.

Fig. 2 is a perspective view illustrating a set of the main components of the heating cooker according to the first embodiment.

Fig. 3 is a perspective view illustrating the thermal insulation members of the heating cooker according to the first embodiment.

Fig. 4 is a perspective view schematically illustrating the directions of the coil current flowing through the coils of Fig. 2, and the directions of the induction currents flowing through the heaters.

Fig. 5 is an enlarged partial cross-sectional view of the induction heating means according to the first embodiment.

Figs. 6A and 6B are plan views illustrating the heater of the heating kitchen according to the first embodiment, in a structural and functional manner, respectively.

Fig. 7 is a cross-sectional view of the heating stove according to the modification of the first embodiment, similar to Fig. 1.

Fig. 8 is an enlarged cross-sectional view of the induction heating means according to the modification of the first embodiment, similar to Fig. 5.

Fig. 9 is a cross-sectional view of the induction heating means used in an experiment of the first embodiment.

Fig. 10 is a plan view of the induction heating means used in an experiment of the first embodiment, showing various measuring points of the heater.

Fig. 11 is a graph showing a higher temperature measured at each of the measuring points of the heater in the experiment.

Fig. 12 is a cross-sectional view of the heating cooker according to the second embodiment of the present invention.

Fig. 13 is a perspective view illustrating a set of the main components of the heating cooker according to the second embodiment.

Fig. 14 is a graph showing a higher heater temperature measured in the experiment according to the second embodiment.

Fig. 15 is a cross-sectional view of the heating cooker according to the modification of the second embodiment.

Fig. 16 is a diagram showing a relationship between the higher temperature of the heater and the length of the magnetic member according to the modification of the second embodiment.

Fig. 17 is a perspective view illustrating a set of the main components of the heating cooker according to a further modification of the second embodiment.

Fig. 18 is a cross-sectional view of the heating cooker according to the third embodiment of the present invention.

Fig. 19 is a perspective view illustrating a set of the main components of the heating cooker according to the third embodiment.

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Fig. 20 is an enlarged partial cross-sectional view of the induction heating means according to the third embodiment.

Fig. 21 is an enlarged cross-sectional view of the induction heating means according to a modification of the third embodiment, similar to Fig. 20.

Fig. 22 is an enlarged cross-sectional view of the induction heating means according to a further modification of the third embodiment similar to Fig. 20.

Fig. 23 is a cross-sectional view of the heating cooker according to the fourth embodiment of the present invention.

Fig. 24 is a perspective view illustrating a set of the main components of the heating cooker according to the fourth embodiment.

Fig. 25 is a cross-sectional view of the heating stove according to a modification of the fourth embodiment.

Figs. 26A and 26B are cross-sectional views of the heating cooker according to the fifth embodiment, with the mobile component in closed positions and open to the stationary component, respectively.

Fig. 27 is a perspective view illustrating the induction heating means according to the fifth embodiment.

Fig. 28 is an enlarged cross-sectional view of the induction heating means according to the fifth embodiment, taken along a line A-A of Fig. 27.

Fig. 29 is a cross-sectional view of the heating cooker according to the sixth embodiment of the present invention.

Fig. 30 is a perspective view illustrating a heating assembly according to the sixth embodiment.

Fig. 31 is a perspective view illustrating a heating assembly according to a modification of the sixth embodiment.

Fig. 32 is a perspective view illustrating a heating assembly according to a further modification of the sixth embodiment.

Fig. 33 is a perspective view of a lower plate-shaped heater assembly according to a further modification of the sixth embodiment.

Fig. 34 is a cross-sectional view of the bottom of the plate-shaped heater of Fig. 33.

Fig. 35 is a perspective view illustrating a set of the main components of the heating cooker according to a further modification of the sixth embodiment.

Fig. 36 is a developing view of the heater of the heating cooker of Fig. 35.

Fig. 37 is a cross-sectional view of the heater of the heating cooker of Fig. 35.

Fig. 38 is a cross-sectional view illustrating a set of the main components of the heating according to a further modification of the sixth embodiment.

Fig. 39 is a cross-sectional view illustrating a set of the main components of the heating according to a further modification of the sixth embodiment.

Description of reference numbers

1: heating cooker (heating system), 10: heating chamber (box-shaped housing), 12a: upper wall, 12b: lower wall, 16: front wall, 18: rear wall, 20: heater, 22: low resistivity part, 24: energized part, 25: refrigeration part, 26: high resistivity part (heating part), 30: coil, 32: magnetic member, 34: thermal insulating member, 36: groove (opening ), 37: grid, 38: fat receiving source, 40: base part, 42: side part, 44: extended part, 45: thermal insulating member, 50: stationary component, 52 mobile component, 54: access port heater, 56: air-tight housing, 58: bottom heater, 59: cut-out, 70: airtight box-shaped container, 72: lid member, 74: container member, 75: container body, 91, 92: flow magnetic.

kitchen cooking

the main components of the kitchen of

the main components of the kitchen of

the main components of the kitchen of

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Description of the realizations

The present invention relates to any type of heating system and may be applicable even for an industrial cooking oven and drying oven, and also for a domestic heating cooker. Referring to the accompanying drawings, embodiments of a heating cooker as an example of the heating system according to the present invention will be described herein. In the description, a couple of terms to indicate the directions (for example, "upper", "lower", "left" and "right", etc.) are conveniently used only to facilitate understanding, it should not be construed that those terms limit the scope of the present invention. Similar components are indicated with similar reference numbers throughout the description.

Realization 1. Fig. 1 is a cross-sectional view of the heating cooker 1 according to the first embodiment, and Fig. 2 is a perspective view schematically illustrating a set of main components of the heating cooker of Fig. 1. The heating cooker 1 is suitably used for a CI cooker heater, especially useful as a heating chamber for grilling. In addition, the present invention can also be adapted for any other type of heating cookers such as a microwave oven and / or a toaster oven, which is used for various culinary arts, such as oven cooking, as well as grilling.

The heating cooker 1 according to the first embodiment of the present invention includes a heating chamber 10 (box-shaped housing) as illustrated in Figs. 1, 2. The heating chamber 10 includes walls 12a, upper and lower 12b, right and left side walls 14a that extend vertically, and front and rear side walls (not shown). In addition, the heating cooker 1 includes removable heaters 20a, 20b made of metal in a closed loop (in a closed electrical circuit) provided within the heating chamber 10 near the upper and lower walls 12a, 12b. It also includes coils 30a, 30b provided along the right and left side walls 14a, 14b of the heating chamber 10, and a pair of magnetic members 32 of magnetic material such as a ferrite core provided along and adjacent to coils 30a, 30b.

Each of the coils 30a, 30b can be formed, for example, by twisting a plurality (nineteen) of copper wires having a diameter of 0.3 mm coated with wire resin (called Litz wire), and winding the Litz wire a plurality of times (25 times) in parallel with the side walls 14a, 14b in a rectangular shape in which each of its corners is bent into a straight curve or an elliptical shape. In the Litz wire wound along the sides of the rectangular shape of the coil, the current (magnetic flux) circulates in the same direction. As shown in Fig. 2, each of the magnetic members 32 is formed in a U-shape to cover or surround the Litz wires, and is arranged to be placed in front of the upper and lower heaters 20a, 20b.

The magnetic members 32 may be made of a magnetic material similar to one generally used as the ferrite core around the heating coil of a typical CI kitchen heater. In addition, a plurality of U-shaped thermal insulating members 34 are provided inside each of the U-shaped magnetic members 32. In this way, the coils 30a, 30b are interposed between the magnetic members 32 and the thermal insulation members 34, at least in parts where the coils face the heaters 20a, 20b, as illustrated in Figs. 1 and 2. In addition, the thermal insulation members 34 may have a double layer structure having a thermal insulation layer 34a made of glass wool or ceramic wool and a ceramic layer 34b as shown in Fig. 3 , and a part of the side walls 14a, 14b of the heating chamber 10 may be formed in ceramic or metal, such as iron and stainless steel.

The thermal insulating members 34 structured in this manner thermally release the coils 30a, 30b and the magnetic members 32 of the hot atmosphere inside the heating chamber 10. In addition, the insulating layer 34a is formed as an air space or air stream. The parts of the side walls 14a, 14b may be composed of the thermal insulation members 34 and the magnetic members 32 together with the coils 30a, 30b as illustrated in Fig. 1. The other parts of the walls that make up the heating chamber 10 (for example, upper and lower walls 12a, 12b) are made of metal, such as iron and stainless steel or heat-resistant insulating material such as ceramics and glass. Although not shown, the heating chamber 10 is also defined by the front and rear walls. In this way, the heating chamber 10 is formed as a closed box or housing of the upper and lower walls 12a, 12b, the side walls 14a, 14b and the front and rear walls. The front wall has a front door (not shown) that can be opened and closed to access the food inside the heating chamber 10.

The heaters 20a, 20b are inserted and supported within grooves (openings) 36 of the thermal insulation members 34, each of which extends horizontally as shown in the drawings. In this way, the heaters 20a, 20b are simply located or seated in the grooves 36, which allows the heaters to be disassembled from the main door. In addition, this structure of the heating chamber 10 allows both a grid 37 to support the food and a source 38 for receiving fat from the food to be inserted into and / or disassembled from the heating chamber 10 through the

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front door. The grid 37 and the fat receiver source 38 can be made of materials and can be structured in any of the configurations used in the heating chamber 10 of a conventional CI kitchen heater. Also, preferably, the side walls 14a, 14b and the other walls of the heating chamber 10 may have interior surfaces coated with material suitable for various purposes, achieving an antifouling effect and an infrared ray effect.

Next, the operation of the heating cooker 1 will be described. When the high frequency current having a frequency in a range of 20 kHz to 100 kHz is supplied with the coils 30a, 30b from a power circuit (not shown), a high frequency magnetic field is generated by and around the coils 30a, 30b. The high frequency magnetic flux generated by the coils 30a, 30b defines a magnetic loop that flows through the U-shaped magnetic members 32, the heaters 20a, 20b and the grooves (openings) 36 of the thermal insulating members 34 . In this way, the heaters 20a, 20b are magnetically interconnected with the high frequency magnetic flux. Next, an induction current is generated through each of the heaters 20a, 20b that are electrically closed or formed as a loop, and then heat is generated by Joule effect by the induction current, so that the heaters 20a, 20b are heated completely and uniformly. Said complete and uniform heating by the heaters 20a, 20b heats the food received inside the heating chamber 10 in a uniform manner. When the power circuit supplies enough power (for example, 2 kW in total) with the coils 30a, 30b, the heaters 20a, 20b are heated to more than 800 degrees C, from which infrared energy is radiated to directly heat the food . In addition, the heaters 20a, 20b heat the peripheral atmosphere that is distributed by convection through the heating chamber 10 and then indirectly heats the food in the hot atmosphere. As indicated above, the food inside the heating chamber 10 is heated by infrared radiation and the hot atmosphere, for cooking on the grill.

The fat flowing from the food to be heated is received by a source 38 receiving fat provided under the lower heater 20b. According to the present invention, in principle, the induction current circulates through the lower loop heater 20b, thereby generating heat by Joule effect. This is a different heating principle from the conventional heating cooker described in the patent documents 1, 2 above, where the magnetic body is directly heated by induction. Therefore, even if the grease receiving source 38 is made of metal and is arranged under the lower heater 20b, it is not directly heated by induction by the lower heater 20b and, therefore, the fat receiving source 38 can be maintained. at a temperature much lower than the ignition temperature of the grease, increasing the gap between the lower heater 20b and the fat receiving source 38.

As indicated above, according to the present invention, the heating principle that uses Joule heat generated by the induction current flowing through the loop heater is different from the "induction heating" principle for seated vessels. on the top plate of a typical CI kitchen heater and, thus, the principle of heating the present invention cannot be referred to as "induction heating". However, because the present invention uses Joule heat generated by the "induction current" that circulates through the loop heater caused by "electromagnetic induction," this application also uses the expression "induction heating. " In the present memory. In addition, the coils 30a, 30b and the magnetic members 32 are collectively referred to as "induction heating means" to generate an induction current through the heaters 20a, 20b. It should be noted that the temperature and the input energy of the heaters 20a, 20b have been indicated above as an example, and the temperature of the heaters 20a, 20b can be determined by parameters that include the input energy and the surface area of radiation thereof, etc.

Although not described in detail, any type of power circuit that is similar to those used in a typical induction heating cooker such as an IC cooker can be incorporated, including, for example, a half bridge circuit, a bridge circuit complete and an oscillator circuit. As it can easily be configured by a person skilled in the art without an additional description of the power circuitry in the embodiments, an oscillating capacitance is connected in series with the coil used in the half bridge circuit and the complete bridge circuit. , and used in parallel in an oscillator circuit. This is well known in the art and, therefore, is also adapted in other embodiments according to the present invention. In addition, it should be noted that each of the coils 30a, 30b is powered individually with respect to the respective circuit between the power circuits, or the coils 30a, 30b connected in parallel or in series with each other can be powered with energy from The same power circuit. When the coils 30a, 30b are connected in parallel or in series with each other, attention should be paid to their connection, taking into account the direction of the current flow, which will be described later in the present specification.

Fig. 4 illustrates the directions of the coil currents flowing through the coils 30a, 30b, the directions of the magnetic flux generated by the coil current, and the directions of the induction current that circulates through

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the heaters 20a, 20b induced by electromagnetic induction. To facilitate understanding, all components except coils 30a, 30b and heaters 20a, 20b are removed. In Fig. 4, the flow directions of the coil current and the induction current are drawn on the coils 30a, 30b and the heaters 20a, 20b. The coil current and induction current have flow directions alternated to the drive frequency, and Fig. 4 is illustrated at a given time in the flow directions. As illustrated in Fig. 4, the coil current through the coils 30a, 30b generates the magnetic flux around the coils 30a, 30b with which the heaters 20a, 20b are magnetically interconnected, thus developing a electromotive force and generating the induction current through the heaters 20a, 20b formed in a closed loop. Thus, this mechanism is the same as that of a transformer, in which the coils 30a, 30b can be considered as equivalent to the primary coils, and in this way the heaters 20a, 20b are like the secondary coils of the transformer. Because the heaters 20a, 20b are heated using said mechanism, when the coils 30a, 30b connected in series or in parallel are driven by a single power circuit, the coils 30a, 30b must be connected so that the coil current flows as shown in Fig. 4. On the other hand, when each of the coils 30a, 30b is driven by an individual power circuit, the phase (or direction) of the coil current through The coils 30a, 30b can be adjusted to obtain any desired heating efficiency (or controllable), and can be adjusted to an optimum value to achieve the highest heating efficiency when the phase (or direction) is controlled as shown in the Fig. 4.

Fig. 5 is an enlarged cross-sectional view of one of the four induction heating means of the heating cooker 1 in Fig. 1, which includes the coil 30 and the magnetic member 32 (together with the members 34 of thermal insulation and heater 20). In Fig. 5, heater 20 is illustrated only for a part that magnetically interconnects with the magnetic flux. As the high frequency current flows through the coil 30, the high frequency magnetic flux around the coil 30 is generated. The high frequency magnetic flux flows through a magnetic circuit (loop) that penetrates the U-shaped magnetic member 32 and passes through the U-shaped opening thereof. In this context, the "U-shaped magnetic member 32" is defined to include a base portion 40 that extends along the coil 30, and a pair of side portions 42a, 42b that extend perpendicularly to the base part 40 from its ends, between which the opening 36 is formed.

The magnetic flux extending through the opening 36 of the U-shaped magnetic member 32 includes a flow (91) that does not pass through the heater 20 and another flow (92) that penetrates the heater 20. Although the flow (9I) magnetic is quite effective in generating the induction current through the electrically loop heater 20, the magnetic flux (92) is less effective because its magnetic energy is used, for the most part, to generate currents parasites inside the part where the magnetic flux penetrates but little to generate the induction current in the entire heater 20 in loop. In this way, the heater 20 is heated by the heat by Joule effect caused by the induction current and also the parasitic current. Therefore, because the heater 20 is made of a uniform material and formed with the same section along its extension direction, in general, it has higher temperatures in the parts that are closer to and magnetically interconnected with the coils 30a, 30b, and a lower temperature in the other parts. The magnetic energy of the magnetic flux (92) closer to the coils 30a, 30b also contributes to heating the atmosphere inside the heating chamber 10, without loss of energy, however, this requires a further improvement of the thermal insulation between the coil 30 (and the magnetic member 32) and the heater 20, providing an air space for air to circulate therethrough and / or designing the thicker thermal insulation member 34 to thermally protect the coil 30.

Figs. 6A and 6B are plan views of the heater 20 suitably used in the heating cooker 1 of the first embodiment. The heater 20 is structurally illustrated in Fig. 6A and functionally in Fig. 6B. It should be noted that the heater 20 used for the heating cooker 1 of the present invention is not limited thereto, and can be formed in any form and configuration with any material provided it is formed in an electrically closed loop. Preferably, the heater 20 may be composed of two structurally different parts of each other. That is, the heater 20 may include low resistivity parts 22 that have lower electrical resistance in the end regions adjacent to the coils 30a, 30b, and high resistivity parts 26 that have greater electrical resistance in half thereof. The expressions, that is, the "low resistivity" part and the "high resistivity" part are intended to indicate that they have an electrical resistance per unit of length less or greater than one another. For example, when the same metal is used for both parts 22, 26, the low resistivity part 22 and the high resistivity part 26 can be formed from a solid bar and a hollow tube, respectively, and can be connected to each other. , for example, by welding. In addition, when a different metal is used for each part 22, 26, the low resistivity part 22 may be made at a lower specific resistance such as copper and the high resistivity part 26 may be made at a higher specific resistance, such as stainless steel. In addition, the low resistivity part 22 and the high resistivity part 26 may have a different structure and material from each other. For example, the low resistivity part 22 may be made from a solid copper or copper alloy bar having a diameter of 6 mm, and the high resistivity part 26 may be made in a hollow stainless steel tube which has a diameter of 6 mm and a radial thickness in a range between 0.3 mm and 1 mm, which are connected to each other by welding or gluing. It should be noted that, because the terms, that is, "resistance

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specific "refers to a resistance at a given high frequency of the induction current through the heater 20, the hollow bar may possibly have the lower specific resistance than that of the solid due to the skin effect and, if this is the case, The low resistivity part 22 may be made in a hollow tube.

Because the heater 20 does not include any electrical core such as a heating wire of an insulating cover heater, the heater 20 can be formed in any configuration as shown in Figs. 6A and 6B at a reasonable cost and without damage when folded. In addition, the heater structured in this manner may be coated with various materials for an antifouling and / or protective effect.

Heater 20 will be described herein in a functional aspect. The low resistivity part 22 shown in Fig. 6B is composed of an energy-fed part 24 and a cooling part 25. The high resistivity part 26 shown in Fig. 6A is also called a heating part 26.

Next, the operation thereof will be explained herein. As described above, the heater 20 includes the low resistivity part 22 composed of the energy-fed part 24 and the cooling part 25 both made in a solid copper bar, and the high resistivity part 26 (part of heating) of a stainless tube. As illustrated in Figs. 1 and 2, the heater 20 is inserted into the slots (openings) 36 of the thermal insulation members 34 and is located inside the heating chamber 10. When the coil 30 is fed with high frequency current by the power circuit, a high frequency magnetic flux is generated around the coil 30, which is magnetically interconnected with the part 24 fed with energy to generate an induction current through of the heater 20. Next, while the part 24 fed with energy is heated in response to heat by Joule effect caused by the induction current and the parasitic current, because it has a lower relative resistance, the induction current generates less heat by Joule effect in it. In addition, because the energy-fed part 24 is made of a material that has low relative resistance, such as a non-magnetic metal (for example, copper), it is possible to sufficiently reduce the heat by Joule effect generated by the parasitic current.

Because the energy-fed part 24 is located within or surrounded by the groove 36 of the thermal insulation member 34, it is cooled less than the cooling part 25. Although the cooling part 25 has the same structure and the same construction material as the energy-fed part 24, because the cooling part 25 is surrounded by air, it is cooled much more than the energy-fed part 24. In addition, the part

25 refrigeration is made of a material that has less resistance, the heat by Joule effect by the induction current is reduced and maintained at a relatively lower temperature.

Meanwhile, the heating part 26 is globally exposed to the air, it is cooled just like the cooling part 25, however, because the heating part 26 has a greater electronic resistance, it generates more Joule effect heat by the current of induction that the refrigeration part 25. Therefore, the food inside the heating chamber is heated and grilled efficiently by the heat of radiation from the part

26 heating. In addition, the cooling part 25 generates less heat and radiates more heat transferred from the heating part 26 to the peripheral air, which minimizes the heat generated by the heating part 26 and transferred through the cooling part 25 to the part 24 fed with energy, thus maintaining part 24 fed with energy at a lower temperature.

Next, the magnetic member 32 defining the magnetic loop (magnetic circuit) is described here. As shown in Fig. 5, the high frequency current through the coil 30 generates the high frequency magnetic flux around the coil 30 defining the magnetic circuit that flows through the U-shaped magnetic member 32 and through the opening 36. As described above, although the magnetic flux (92) penetrates through the heater 20, but the magnetic flux (9I) does not, both magnetic fluxes generate an induction current that crosses the heater 20. In order to obtain a higher induction current through the heater 20, preferably the magnetic flux (9I) is increased as much as possible. Also in order to reduce the heat by Joule effect due to the parasitic current in the part 24 fed with energy, it is desirable to reduce the magnetic flux (92), to thereby increase the ratio of the magnetic flux (9I) with respect to the Magnetic flow (92).

Fig. 7 is a cross-sectional view of an improved heating cooker 1, which is generally similar to that illustrated in Fig. 1, except that the magnetic member 32 has a different shape and / or configuration. Fig. 8 is an enlarged cross-sectional view of a part of the induction heating means, similar to Fig. 5, which includes the coil 30, the magnetic member 32, the thermal insulation members 34 and the heater 20 The magnetic member 32 of Fig. 8 is basically the same as that of Fig. 5 except its shape and / or configuration so that the magnetic member 32 is improved to increase a ratio (91/92) of the magnetic flux.

While the magnetic member 32 of Fig. 5 has a U-shaped cross section, the magnetic member 32 of Figs. 7 and 8 has a C-shaped cross section. In this application, the "C-shaped magnetic member" is intended to refer to one that includes a base portion 40 that extends along the coil 30,

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a pair of side parts 42a, 42b extending perpendicularly to the base part 40 from the ends thereof, and a pair of extended parts 44a, 44b extending from the tips of the side parts 42a, 42b toward each other. another, among which the opening 36 is formed. In this way, the magnetic member 32 of Fig. 8 has a cross section that has a rectangular shape having a partially open or broken member in its center. The magnetic member 32 may have a trapezoid or oval shape instead of the rectangular shape.

As illustrated in Figs. 7 and 8, the C-shaped magnetic member 32 reduces the magnetic resistance of the magnetic flux (91), thereby increasing the magnetic flux (91) between the extended portions 44a, 44b and reducing the magnetic flux (92). Therefore, the C-shaped magnetic member 32 of Figs. 7 and 8 reduces the heat by Joule effect by the parasitic currents within the energy-fed part 24 of the heater 20, as compared to the C-shaped magnetic member 32 of Fig. 5. Thus, it is preferable to design the magnetic member 32 in the C-shaped configuration. However, in the case where the groove (opening) 36 has the same width, the C-shaped magnetic member 32 requires a larger volume of construction material than the member U-shaped magnetic 32 and, therefore, increases the manufacturing cost of the C-shaped magnetic member 32. In addition, as described above, in order to keep the part 24 energized at a higher temperature low, it may not be necessary for the energy-fed part 24 and the heating part 26 of the heater 20 to be structured or formed in a different way, so that the manufacturing cost of the heater 20 is substantially reduced. In other words, after considering the other design factors such as manufacturing cost, it must be determined whether or not the U-shaped or C-shaped magnetic member 32 is incorporated.

It is more preferable that the C-shaped magnetic member 32 has the smallest opening 36 (smaller distance between the extended parts 44a, 44b), and it is more desirable that the distance between the extended parts be zero and that the magnetic member 32 have an O-shaped cross section. However, if the magnetic member 32 is designed to have an O-shape, the heater 20 cannot be disassembled from the magnetic member 32 and, therefore, another innovative structure having the heater is required. 20 detachable. Also in order to make the opening 36 of the magnetic member 32 smaller, the heater 20 can be formed from a metal plate instead of a bar or tube having a circular cross-section. For example, the heater 20 made in a non-magnetic stainless steel plate having a thickness of 2 mm may cause the opening 36 (the distance between the extended parts) of the C-shaped magnetic member 32 to be 4 mm smaller.

Next, an experimental result will be described. When the coils 30a, 30b of the structured heating cooker 1 are fed as in Fig. 2 with the high frequency current, the temperature of the heaters 20a, 20b was measured. The upper wall 12a and the front wall of the heating chamber 10 of Fig. 2 were kept open in this experiment. This is because the temperature of the heaters 20a, 20b was detected directly by a thermocouple, and overheating of the heating chamber 10 should be prevented. Fig. 9 is a cross-sectional view of the induction heating means of the heating chamber 10 used in the experiment, in which the size of the scale thereof almost doubled exactly with respect to those actually used. . The magnetic member 32 has the C-shaped cross section shown in Fig. 9 and the length of 60 mm along the depth direction in the drawing. The magnetic member 32 is made of ferrite core and has a thickness of 5 mm. The thermal insulation member 34 is made of ceramic wool and has a thickness of 10 mm. The coil 30 was formed by winding the nineteen twisted copper wire Litz cable 25 times that fear a diameter of 0.3 mm coated with resin wire. The coils 30a, 30b provided on the left and right side walls of the heating chamber 10, as shown in Fig. 2, were connected in parallel and fed with the 25 kHz high frequency current from a circuit half bridge power. The heater 20 has a circular cross section having a diameter of 6 mm. As seen in Fig. 9, the heater 20 is positioned near the opening 36 of the U-shaped magnetic member 32 and, therefore, there seems to be an insufficient magnetic flow (91) that passes through (or does not penetrate through) the heater. Fig. 10 shows the structure of the heater 20 used in the experiment, in which the size of the scale thereof has almost doubled exactly with respect to those actually used. The heater 20 was constructed so as to have two different types of material and configuration, also as shown in Fig. 6. In Fig. 10, the low resistivity part 22 was made from a copper rod that It has a diameter of 6 mm and the part 26 of high resistivity was made from a hollow tube of non-magnetic SUS 304 stainless steel, which has an outer diameter of 6 mm, an inner diameter of 4 mm and a radial thickness of 1 mm The copper bar (part 22 of low resistivity) and the stainless tube (part 26 of high resistivity) were connected by gold welding. A pair of parts, as shown by the left and right dashed line rectangles in Fig. 10, were inserted into the grooves 36 of the thermal insulation members 34 when they were located within the heating chamber 10. In this manner, the heater 20 structured in this manner does not include any cooling part 25 as shown in Fig. 6B. Various points at which thermoelectric pairs were provided for thermal measurements are indicated by solid A-D drums in heater 20 of Fig. 10. Thermoelectric pairs were fixed by winding a Kapton tape at those points. Due to the thermal resistance limit of the Kapton tape, the temperature was measured in a range below 400 degrees C.

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Fig. 11 is a graph showing the temperature detected at each of the temperature measurement points of the heater 20 when the power circuit is fed with a power of 1 kW. Temperature measurements were made in the upper heater 20a at points A, B, C, D in Fig. 10, and in the lower heater 20b at points A, B, C. The indication "parts powered by energy" in Fig. 11 it indicates the temperature detected in points A, B, and the indication "heating parts" in Fig. 11 indicates the temperature detected in points C, D. The temperatures in the heaters 20a, 20b higher and lower detected at each of the points are approximately equal to each other, these measurements are shown in Fig. 11 without distinguishing the heaters 20a, 20b upper or lower.

As clearly shown in Fig. 11, the heating cooker 1, which has the heater 20 of Fig. 2, is used for heating and cooking food. Because the heating part 26 of the heater 20 at each measuring point has approximately the same temperature, it is clear that the heating part 26 is heated by the heat by Joule effect caused by the induction current flowing through the heater 20 in loop. The rate of thermal increase of the heating part 26 is substantial, which is due in part to the lower thermal capacity of the heating part 26 made from a stainless tube. For example, two minutes after starting the heating, the temperature of the heating parts 26 is much higher than that of the energy-fed parts 24, which also clearly shows that the heating parts 26 heat themselves and not by the heat transferred from the parts 24 fed with energy.

The present invention seems similar to the patent document 3 indicated above in the sense that magnetic cores are used to apply the high frequency magnetic flux through the side walls, but it is totally different in regard to the heating mechanism. Thus, according to patent document 3, only the side parts of the furnace source are magnetically interconnected with each other with the magnetic flux to be heated by the induction current flowing through them. Contrary to this, according to the present invention, the heater assembly 20, instead of only the parts 24 supplied with energy from the heater 20 is heated by induction by the induction current flowing through the loop heater 20, which is caused by the high frequency magnetic flux that passes through (does not penetrate through) the parts 24 powered by heater 20.

The temperature of the energy-fed part 24 increases moderately but ultimately more than that of the heating part 26. This is partly because the energy-fed part 24 is heated by the parasitic current generated by the magnetic flux that flows through the energy-fed part 24. This is also because a part of the heating part 26 connected to the energy-fed part 24 is received in the groove 36 of the thermal insulation member 34, as shown in Fig. 10 so that the part of the heating part 26 radiates less thermal energy than the other parts (at measuring points C, D), thereby raising its temperature. The heat from the elevated part of the heating part 26 is transferred to the energy-fed part 24 which also radiates less thermal energy, which can make the temperature of the energy-fed part 24 higher. In other words, it is useful to provide the refrigeration part 25 as shown in Fig. 6B in order to lower the temperature of the energy-fed part 24. It may not be necessary to mention that, although the temperature of the heating part 26 in the experiment of Fig. 11 is relatively low for grill cooking, the temperature of the heating chamber 10 may be high, providing the upper wall 12a and the front wall of it and providing more energy, which is suitable for grilling.

The heating chamber 10 of the heating kitchen 1 of Figs. 1 and 2 may include the side walls 14a, 14b made of metal, such as an iron plate, which can also be heated by induction by the magnetic flux generated by the coils 30a, 30b, as well as the magnetic members 32. However, the side walls heated by induction can efficiently increase the temperature of the air inside the heating chamber 10.

As explained above, the heating cooker 1 according to the present invention includes the induction heating means in the side walls 14a, 14b of the heating chamber 10. In addition, the heating cooker 1 includes electrically loop heaters 20a, 20b that are removably disposed within the heating chamber 10 and are generally heated by an induction current generated by a high frequency magnetic flux from the walls 14a , Lateral 14b. This allows the heating chamber 10 to be cleaned more easily and the metal fat receiving source 38 to be placed below and far enough away from the lower heater 20b.

It is not always necessary to provide two heaters 20a, 20b upper and lower inside the heating chamber 10, and it is possible to dispose only one of them inside. When only one heater is provided, a single induction heating means can be positioned adjacent to any one of the upper and lower heaters 20a, 20b with the coil 30 wound in a flat shape like the present embodiment. This also applies to

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any of the following embodiments.

Embodiment 2. Fig. 12 is a cross-sectional view of the heating cooker 1 according to the second embodiment of the present invention, and Fig. 13 is a perspective view schematically illustrating a set of main components of the cooking cooker. heating of Fig. 12. The induction heating cooker 1 of the second embodiment is similar to one of the first embodiment except that only one coil is provided on the side wall 14 to supply the high frequency magnetic flux with the heater 20 formed in an electric loop. Therefore, the duplicate detailed description of common features will be deleted. Similar components are indicated with similar reference numbers throughout the description.

As is evident when comparing Figs. 12 and 13 of the heating cooker 1 according to the second embodiment with Figs. 1 and 2 thereof according to the first embodiment, the heating chamber 1 of the heating cooker 1 according to the second embodiment includes only a means of induction heating. This works well, as is clearly understood from the heating principle of the heating cooker 1 of the present invention that the heater is magnetically interconnected with the high frequency magnetic flux generated by the electromagnetic induction, so that the current induction circulates through the heater formed in an electric loop. Therefore, the second embodiment will be described as including an induction heating means having a set of a coil and other components, while it is possible to have two sets as in the first embodiment, or to have three or more sets thereof. . In addition, what has been described for the first embodiment may naturally be applicable for the heating cooker 1 according to the second embodiment.

In Fig. 12, the heating chamber 10 includes the left side wall 14b having grooves 39 to support the heaters 20a, 20b but not the coil 30 disposed thereon. The side wall 14b may be formed in a metal material such as iron, in which at least one of the side wall 14b and the heaters 20a, 20b must be coated with insulating material for electrical insulation between both heaters 20a, 20b. In general, the inner walls of the heating chamber 10 and the heaters 20a, 20b are coated with material for an anti-fouling, protective and / or far-infrared effect, therefore, such a coating can also be adapted for an electrical insulation effect.

Next, an experimental result will be described. Fig. 14 is a graph showing the measured temperature of the heater 20 of the heating chamber 10 shown in Fig. 13. The driving condition of the induction heating cooker 1 of the second embodiment is similar to one of the first embodiment except that a single induction heating medium is used. Thus, the input energy was 500 W. As is clearly understood from the graph of Fig. 14, the parts 24 fed with energy fear a higher temperature than the heating parts 26. Because the upper and lower heating parts 20a, 20b fear the different increased temperature between them in this experimental result, each of the measurements is plotted individually in Fig. 14. The temperature of the heaters 20a, upper 20b and The lower one is different from each other, which is understandable since each of them has a different position or relationship in relation to the induction heating means and the lower heater is fed with more energy. The heating parts 26 fear the saturated temperature after approximately six minutes have elapsed, but the temperature of the energy-fed parts 24 continued to rise subsequently. This is understandable since the temperature of the heating parts 26 is increased by its own heat rather than by the heat transferred from the energy-fed parts 24.

After a comparison with Figs. 11 and 14 for the first and second embodiments of the heating cooker 1, it is evident that the parts 24 fed with energy have increased their temperature more than the heating parts 26, the reason of which is understood as follows. Thus, although the temperature of the heating parts 26 depends on the input energy, the amount of heat generated by the heating parts 26 with an input energy of 500 W according to the second embodiment in Fig. 14 is approximately half of that generated by the heating parts 26 with the input power of 1 kW according to the first embodiment in Figs. 11, which reduces the temperature of the heating parts 26 of Fig. 14. While, because one of the induction heating means is fed with 500 W energy in both first and second embodiments, the amount of heat generated by the parasitic current in the power-fed parts 24 of Fig. 14 is almost equivalent to that of Fig. 11. Thus, although the input energy to the induction heating means of Fig. 14 is reduced by half, the energy-fed parts 24 of Fig. 14 have an increased temperature substantially equal to that of Fig. 11. Thus, when the heating cooker is designed to have a unique heating medium by induction of the coil 30 and other components, more heat is generated in the parts 24 fed with energy, therefore, it is useful to form the magnetic member in the C-shape as described in the first embodiment to increase the magnetic flux that passes through (does not penetrate through) the heater 20 and reduce the penetrating magnetic flux magnetically interconnected with the heater 20. This can suppress the temperature rise of the energy-fed parts 24 and increase the temperature of the heating parts 26, even when the heater 20 has a part 24 powered by energy. When heater 20 is

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provided with a part 24 fed with ene, that is, when a means of induction heating is required, the manufacturing cost is advantageously reduced. In addition, it provides another advantage in that the degree of freedom to design the structure of the heating cooker 1 can be extended by providing the induction heating means only on the front wall 16 or the rear wall 18 as shown in Fig. 15, instead of on the side wall 14. Fig. 15 is a cross-sectional view of the heating cooker 1 which includes the induction heating means arranged in the rear wall 18. The magnetic member has the C-shaped cross section in order to suppress the temperature rise of the energy-fed parts 24. In addition, the front wall 16 of the housing (the heating chamber 10) can be structured to be open and closed, and is partially composed of a front door 17 made of glass through which the interior of the same can be observed during The cooked. The principle of heating the induction heating means arranged in the rear wall 18 is similar to that of the side wall 14 as described in the previous embodiments.

Despite the only induction heating medium, the heater 20 having two of the low resistivity parts 22 at both ends thereof is used in this experiment, as illustrated in Figs. 6A, 6B and 10. The heater 20 allows the user to easily install it inside the heating chamber 10 without paying attention to its direction, which eliminates or alleviates the complexity of the installation for the user and prevents the malfunction due to an installation in a wrong direction (installation in the wrong direction) of the heater 20.

Fig. 16 is a graph showing the temperature rise of the heaters 20 that include one or two of the parts 24 energized for comparison. The horizontal axis of Fig. 16 indicates the length of the magnetic member 32, and the increase in the temperature of the magnetic member 32 having a single part 24 fed with energy 60 mm long is obtained by the experiment of Fig. 14 , and the temperature increase of the magnetic member 32 having two parts 24 fed with 60mm long energy is detected by the experiment of Fig. 11. In this way, the structure of the heating chamber 10 and the conditions of actuation of the induction heating means are the same as those of the first and second embodiments. The vertical axis of Fig. 16 indicates a relative increase in temperature when the temperature rise of the only part 24 fed with 60mm long energy measured at 30 seconds after the start of the power supply. The input energy to the induction heating means is established as 500 W with the only part 24 supplied with energy and as 1 kW with the two parts 24 supplied with energy. Thus, any one of the parts 24 fed with energy is fed with an energy of 500 W. The reason why the temperature rise is measured at 30 seconds after the start of the power supply is to compare the increase in temperature of the parts 24 energized when they are not too hot to reduce the influence of heat radiation. Although two of the heaters 20a, 20b are provided, in the case where each of them has two parts 24 powered by energy, the temperature increase is shown in Fig. 16 averaging the temperature of the parts 24 fed with energy

As can be seen in Fig. 16, the increase in the temperature of the energy-fed part 24 with two of the energy-fed parts 24 is less than that of an energy-fed part 24. Also, because the magnetic member 32 is longer, the increase in the temperature of the energy-fed part 24 is less, but is not proportional to its length and is almost saturated to the length of 120 mm or greater in this experiment of Fig. 16. In addition, the increase in the temperature of the energy-fed part 24 with two of the energy-fed parts 24 each having a length of 60 mm is almost equal to the temperature increase as with a only part 24 powered with energy that is 120 mm long. However, if the heating cooker 1 is fed with 1 kW energy, each of the two parts 24 fed with energy is heated with an energy of 500 W as a continuous line in Fig. 16, while a single part 24 powered by energy is heated with the energy of 1 kW as a broken line, whose temperature is almost double that of the previous one.

Therefore, even when the magnetic member 32 has an equal total length between sf, one that has two parts 24 fed with energy is more advantageous than one that has a single part 24 fed with energy. This is because the energy-fed part 24 is a source of energy and it is effective to provide more sources of energy in number for the generation of induction current through the heater. As described above, the magnetic member 32 having the C-shaped cross section advantageously suppresses the temperature increase of the energy-fed part 24 compared to the U-shaped cross section. On the other hand, when the heater 20 is provided with the only part 24 supplied with energy only on any one of the side walls 14, the rear wall 18 and the front wall 16 of the heating chamber 10, the heating chamber 10 can be simply structured, designed with a greater degree of freedom, and manufactured at a more reasonable cost.

Fig. 17 is a perspective view schematically illustrating an assembly of the heating cooker, which includes the heater 20 provided with two energy-fed parts 24 and the induction heating means arranged in the rear wall 18 of the chamber 10 heating Fig. 17 also illustrates only the components

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main heating stove similar to Fig. 2 and eliminates thermal insulation members 34 for the sake of clarity. Thus, although it is not shown, the heating chamber 10 of Fig. 17 is also composed of the side wall 14 and others required to define the heating chamber 10, as shown in Fig. 1. Each of the heaters 20a, 20b is provided with two of the parts 24 powered by energy near the rear wall 18 of the heating chamber 10. A single coil 30 is arranged outside the heating chamber 10 adjacent to its rear wall 18, in this way four of the total U-shaped magnetic members 32 are provided along the coil 30. Each of the members 32 magnetic can also have a C shape.

When fed with high frequency current, the coil 30 generates a high frequency magnetic flux with which the heaters 20a, 20b are magnetically interconnected, thereby inducing a current through the heaters by electromagnetic induction. Because each of the heaters 20a, 20b has two parts 24 energized, even with a single coil provided along the rear wall 18, the temperature rise of the parts 24 energized can be suppressed, while the high temperature of the heating part 26 is maintained.

Embodiment 3. Fig. 18 is a cross-sectional view of the heating cooker 1 according to the third embodiment of the present invention, and Fig. 19 is a perspective view illustrating a set of the main components of the cooking cooker. heating of Fig. 18. The induction heating cooker 1 of the third embodiment is similar to that of the first embodiment except that the coil 30 is formed by spirally winding a conductive cable around the magnetic member 32 in order to supply the High frequency magnetic flux with heater 20 formed in an electric loop. Therefore, a detailed duplicate description of common features will be deleted. Similar components are indicated with similar reference numbers throughout the description.

As illustrated in Figs. 18 and 19, each of the coils 30a-30d is formed by winding a conductive wire such as a Litz wire around the base part 40 of the magnetic member 32 which has the U-shaped configuration. Although only the coils 30a are shown , 30c in Fig. 19, the other coils 30b, 30d are invisible behind the thermal insulation members 34, but in reality they exist. Each of the coils 30a-30d can be fed with high frequency current by an individual energy circuit (not shown). A pair of coils 30a, 30c and a pair of coils 30b, 30d can be electrically connected in series or in parallel to be fed with high frequency current by two of the power circuits, respectively. Alternatively, a pair of coils 30a, 30b and a pair of coils 30c, 30d can be electrically connected in series or in parallel to be fed with high frequency current by two of the power circuits, respectively. In addition, all coils 30a-30d can be electrically connected in series or in parallel to be fed with high frequency current by the single power circuit.

Preferably, each of the coils 30a-30d is connected to the induced current that circulates through the heaters 20a, 20b in directions such as those shown in Fig. 4 of the first embodiment. By connecting each of the coils 30a-30d in series or in parallel, or by connecting the pair of coils 30a, 30b and the pair of coils 30c, 30d to a high frequency current supply, the upper and lower heaters 20a, 20b can be heated separately and, therefore, each of the heaters 20a, 20b can be individually thermally controlled and / or any one of them can be operated for a desired cooking purpose.

Figs. 20 and 21 are enlarged cross-sectional views of the induction heating means with the coil 30 generating a magnetic flux according to the third embodiment. The magnetic members 32 of Figs. 20 and 21 have the U-shaped and C-shaped cross sections, respectively. As can be seen from the drawings, the magnetic flows (91, 92) are generated by the coils 30 in a manner similar to that described in the first and second embodiments. In this way, the coils 30 according to the third embodiment can be replaced by others as explained in the first and second embodiments, and also the technique in the first and second embodiments can also be applied to the third embodiment. Also, as illustrated in Fig. 22, the coil 30 can be wound around another part (for example, the side part 42 extending from the base part 40) of the magnetic member 32 different from those of Figs . 20 and 21.

Embodiment 4. Fig. 23 is a cross-sectional view of the heating cooker 1 according to the fourth embodiment of the present invention, and Fig. 24 is a perspective view schematically illustrating a set of main components of the cooking cooker. heating of Fig. 23. The induction heating cooker 1 of the fourth embodiment is similar to one of the first embodiment except that the coil 30 is formed by spirally winding a conductive wire around two of the adjacent magnetic members 32 to supply the high frequency magnetic flux with the heater 20 formed in an electric loop. Therefore, the detailed duplicate description of common features will be deleted. Similar components are indicated with similar reference numbers throughout the description.

In Figs. 23 and 24, four of the magnetic members 32 having a U-shaped configuration are provided

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on the side walls 14 of the heating chamber 10 in a manner similar to the first embodiment, and each of the coils 30a, 30b is formed by spirally winding a conductive wire such as a Litz wire around the side portions 42 of two members 32 magnetic neighbors provided on the side wall of the heating chamber 10. In this way, the conductive wire of the fourth embodiment is spirally wound around the lateral portions 42 of the magnetic members 32 located in and along one of the lateral walls 14 of the heating chamber 10. When a high frequency current is supplied with the coils 30a, 30b structured in this manner, the heaters 20a, 20b are magnetically interconnected with the generated magnetic flux as described in the previous embodiments, which are heated by the induction current. that circulates through them. Although Figs. 23 and 24 illustrate the magnetic members 32 formed in the U-shaped configuration, the magnetic members 32 may have another cross-sectional configuration, such as a C-shaped configuration.

Fig. 25 is a cross-sectional view of the heating cooker 1 having a magnetic member 32 formed in an E-shaped configuration that looks like two neighboring U-shaped magnetic members combined. Thus, the magnetic member 32 of Fig. 25 has a base part 40, a pair of side parts 42a, 42b extending perpendicularly to the base part 40 from its ends, and a middle part 42c extending from the center of it. In addition, the magnetic member 32 shown in Fig. 25 has two grooves (openings) 36a, 36b between the middle part 42c and each of the side parts 42a, 42b. The heaters 20a, 20b are inserted into the slots 36a, 36b, respectively.

Because the E-shaped magnetic member 32 of the fourth embodiment can be considered as a combination of two U-shaped magnetic members, the heating cooker 1 of Fig. 25 is substantially the same as that of Figs. 1 and 2. In this manner, the E-shaped magnetic member 32 is treated as a combined magnetic member composed of two U-shaped magnetic members. Therefore, the E-shaped magnetic member 32 may have upper portions and lower, each of which has a C-shape, and other features in its cross section as explained in the previous embodiments. In addition, the flat coil of the first embodiment can be used together with the E-shaped magnetic member 32 of Fig. 25.

Embodiment 5. Figs. 26A and 26B are cross-sectional views of the heating cooker 1 according to the fifth embodiment of the present invention. Fig. 27 is a perspective view and Fig. 28 is a cross-sectional view showing the induction heating means of the heating cooker according to the fifth embodiment. The induction heating cooker 1 of the fifth embodiment is similar to one of the second embodiment, except that it has another magnetic member 32 that can be mounted to surround the entire cross-section of the heater 20. Therefore, the Detailed duplicate description of common features. Similar components are indicated with similar reference numbers throughout the description.

As described in the above embodiments 1-4, the heating cooker 1 includes the magnetic member 32 formed in the U-shaped or C-shaped cross section, and the heaters 20 magnetically interconnected with a magnetic flux that includes a magnetic flow (91) that does not pass through the heater 20 and another magnetic flow (92) that penetrates the heater 20. In addition, the magnetic flow (91) that passes through (does not penetrate through) the heater is more effective to generate heat by Joule effect in the heating part of the heater 20 due to the reduction of heat by the parasitic current within the part 24 supplied with energy thereof. As will be described herein, the heating cooker 1 according to the fifth embodiment can maximize the magnetic flux that does not penetrate through the heater 20 and causes an optimal magnetic interconnection with it.

Figs. 26A and 26B illustrate the heating cooker 1, including the induction heating means provided on the rear wall 18 of the heating chamber 10 in a manner similar to the second exemplary embodiment shown in Fig. 15, however, the means of induction heating may be arranged on one or both side walls 14 as described in other embodiments. Furthermore, although the coil 30 is illustrated as formed by spirally winding a conductive wire, such as a Litz wire, it can be formed by winding a conductive wire in a flatter configuration as indicated in the first and second embodiments. The heating cooker 1 of Fig. 26 includes the coil 30 and other components that make up the induction heating means, which are structured differently from the heating cooker 1 shown in Fig. 15, but similar to those of any of the embodiments in view of the other components.

The coils 30a, 30b are made by spirally winding a conductive wire around a part of the magnetic member 32 that is O-shaped and has no opening 36 in the cross section. The O-shaped magnetic member 32 is provided with the thermal insulation member 34 to prevent the magnetic member 32 and the coils 30a, 30b from being heated by the heaters 20a, 20b. In addition, another thermal insulating member 45 is provided around the O-shaped magnetic member 32 and along the inner wall of the heating chamber 10 in order to prevent the magnetic member 32 from being exposed to hot air inside. of the heating chamber 10. The thermal insulation member 34 defines the inner groove 36 to receive the fed part 24

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with heater 20. In this way, the parts of the O-shaped magnetic member 32 and the thermal insulation member 45 comprise a mobile component 52 that can be separated and slid in parallel.

In other words, the induction heating means of the heating cooker 1 according to the fifth embodiment includes a stationary component 50 fixed to the heating chamber 10 and a mobile component 52 designed as sliding on the stationary component 50. The stationary component 50 includes the thermal insulating outer member 45, the coil 30, the U-shaped magnetic member 32 and the thermal insulating member 34 with the slot for receiving the power-fed part 24 of the heater 20. Meanwhile, the component 52 mobile includes the thermal insulating outer member 45, the magnetic member 32 for defining a closed magnetic circuit (91) in cooperation with the U-shaped magnetic member 32 of the stationary component 50, and the thermal insulating member 34. Thus, when the mobile component 52 is slid to a closed position, both the U-shaped magnetic member 32 of the stationary component 50 and the cooperative mobile component 52 define a continuous closed magnetic circuit (91).

Fig. 26A illustrates the mobile component 52 in the closed position prepared to supply induction current through the heaters 20a, 20b for heating. Fig. 26B illustrates the mobile component 52 in the open position allowing the heaters 20a, 20b to be disassembled from the heating chamber 10. The mobile component 52 can be operated manually or automatically by mechanical means.

Fig. 27 is a perspective view of the induction heating means showing a concrete structure of the stationary component 50 and the mobile component 52. Although Fig. 27 illustrates the induction heating means provided for the lower heater 20b, it can have a structure similar to that for the upper heater 20a. The illustration places special emphasis on the energy-fed part 24 of the heater 20b, which is formed in an electrically closed loop as described in the previous embodiments. Fig. 27 illustrates the mobile component 52 in the open position on the stationary component 50. As illustrated, the magnetic member 32 of the stationary component 50 is surrounded by the thermal insulation member 34 and is exposed in a part opposite to a lower part (not shown) of the mobile component 52. The exposed portion of the magnetic member 32 may be coated with a thin protective film. The slot 36 provided inside the thermal insulation member 34 is box-shaped, and when the mobile component 52 is closed, the heating chamber 10 is designed to be completely closed, except for a heater access port 54. When the mobile component 52 is closed, the heater access port 54 is structured to have a cross section that adapts to the cross section of the heater 20. Also, when the power-fed part 24 is inserted into the groove. 36 and the mobile component 52 is closed, the heating chamber 10 is formed to be sealed without exchanging the air in the heating chamber 10 with the air in the groove 36. However, in the case where there is a gap formed between the heater access port 54 and the heater 20 and the hot air inside the heating chamber 10 flows into the groove 36, blowing means can be provided to blow outside air into the interior of the chamber 10 of heating to cool the inside of the groove 36 or to increase the pressure in the groove 36 to a higher value than in the heating chamber 10, thus preventing air from entering heat in the groove 36. With said structure, the removable heater 20 and the magnetic member 32 can be achieved with the O-shaped cross section.

Fig. 28 is an enlarged view of the magnetic flux generated by the induction heating means of the heating cooker 1 of Fig. 26A, showing the lower heater 20b, especially the magnetic member 32 having the cross-section shaped of O. As shown in Fig. 28, most of the magnetic flux (91) generated by the high frequency current through the coil 30b passes through the O-shaped magnetic member 32. Therefore, most of the magnetic flow (91) does not penetrate through the heater 20b, with which the heater 20b is magnetically interconnected. As a result, the heater 20 is sufficiently heated by the induction current rather than by the parasitic current generated by the magnetic flow (91).

Although the fifth embodiment has been described for the removable heater 20 with the magnetic member 32 having the O-shaped cross section, it is still advantageous even if the heater is fixed (not removable) to the interior of the heating chamber 10. In this manner, the energy-fed part 24 of the heater 20 formed in a closed electrical loop can be arranged outside the heating chamber 10 and can be heated by induction current caused by the induction heating means having the member 32 O-shaped magnetic. In this case, as seen from inside the heating chamber 10, the heater 20 may have a structure similar to that of an insulating cover heater commonly used for a conventional CI kitchen heater. However, the insulating cover heater is composed of a ceramic covering that surrounds a heating core wire, which is inserted into a metal tube, such as stainless steel and, therefore, its structure is complicated. Also, because the conventional insulating cover heater has the heating core wire inside the metal tube, there is a restriction in the curvature when bending to obtain a desired shape. The more parts of the insulating cover heater fold to obtain the desired shape, the more expensive its production. In addition, because the conventional insulating cover heater has a coverage

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Ceramic stuffed inside the metal tube, has a substantial caloric capacity and requires a lot of time to be heated well. On the other hand, because the heater 20 of the present invention can be made in a stainless steel tube for example, it can be folded or curved more flexibly and more reasonably compared to the insulating cover heater. In addition, when the heater 20 is made of a metal tube that has less heat capacity, it can be heated faster than the insulating cover heater. The heater 20 with the U-shaped or C-shaped magnetic member 32 of the present invention has several advantages over the conventional insulating cover heater, as described in the previous embodiments. Furthermore, even if the heater 20 is designed to be fixed and not removable inside the heating chamber 10, the heater 20 of the present invention still has another merit in the sense that the Joule heat generated by the current The parasite in the energy-fed part 24 can be minimized by means of the O-shaped magnetic member 32 as described in the fifth embodiment. It should be noted that although the present embodiment describes the coil 30 formed by spirally winding a conductive wire around a part of the magnetic member 32, the coil can be formed like other similar ones illustrated in the first or fourth embodiments.

Embodiment 6. Fig. 29 is a cross-sectional view of the heating cooker 1 according to the sixth embodiment of the present invention, and Fig. 30 is a perspective view schematically illustrating a set of main components of the cooking cooker. heating of Fig. 29. The heating kitchen 1 of the sixth embodiment is similar to one of the first embodiment except that the heaters 20a, 20b are provided along the side walls 14 so that the food inside the Heating chamber can be heated from the side surfaces. Therefore, the detailed duplicate description of common features will be removed. Similar components are indicated with similar reference numbers throughout the description.

In the first to fifth embodiments above, the heating cooker 1 includes a heater 20 disposed inside the heating chamber 10 along a substantially horizontal direction, the heating cooker 1 according to the sixth embodiment includes another type of heater 20 However, because the heating principle of the heater of the present embodiment is the same as described above, in this embodiment any one of the induction heating means described in the previous embodiments can also be used.

Fig. 31 is a perspective view illustrating the main components of a heater 20 of the heating cooker 1 of a modification according to the sixth embodiment. Each of the heaters 20a-20d shown in Fig. 31 has the part 24 fed with energy made of a solid metal bar having low resistance (for example, a solid copper bar), and a heating part 28 made in a thin metal plate that has high strength and high melting point (for example, a thin tungsten plate). The heating part 28 is received inside an air tight box 56 of translucent quartz or ceramic that is hermetically sealed and filled with inert gas, such as argon. Like the previous embodiments, when the coils 30a, 30b are fed with high frequency current, the induction current circulates through each of the heaters 20a-20d, so that the heating parts 28 are heated. Because the heating part 28 is made of metal having a high melting point and the sealed housing 56 is filled with inert gas, the heating part 28 can be heated to a high temperature in a range between 1,000-2,000 degrees C This allows a substantial amount of near-infrared and far-infrared radiation from the heating part 28, similar to an electric light bulb, such as a halogen lamp that generates a substantial amount of light, heat and infrared radiation emission. This radiation heating with infrared light causes the food to be cooked on the grill.

Fig. 32 is a perspective view illustrating the main components including a heater 20 of the heating cooker 1 of a further modification according to the sixth embodiment. The upper heaters 20a, 20b are the same as those shown in Fig. 31. The lower heater 58 is made of a metal plate (for example, a stainless steel plate) having a thickness of approximately 2 mm, which has several cuts 59, as illustrated in Fig. 32. Each of the cuts 59 may be of sufficient width to ensure electrical insulation therein.

Structured heating cooker 1 as in Fig. 32 is suitable for grilling a hamburger, for example. In this way, after placing the hamburger on the lower heater 58, each of the coils 30a, 30b is fed with the high frequency current so that it is heated by the upper heaters 20a, 20b and the lower heater 58. The lower heater 58 is heated to approximately 200 degrees C to burn the hamburger as in a pan. The fat coming from the food and falling through the cuts 59 is received at a fat receiving source (not shown) arranged under the lower heater 58. In addition, as explained above, each of the heaters 20a, 20b above radiates infrared light to grill the hamburger.

As shown in Figs. 33 and 34, the lower heater 58 that composes a high core member

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resistivity may be coated on its upper and lower surfaces with a coating element 175 made of insulating material such as ceramic to keep the unexposed cuts and form the lower heater 58 as a plate-shaped configuration. Fig. 33 is a perspective view of an assembly of the bottom plate-shaped heater 20 with the cuts 59 not exposed, and Fig. 34 is a cross-sectional view thereof. In this manner, this lower heater 58 can be formed by coating (inserting or embracing) the metal plate having the cutouts 59 with the insulating material lining element 175, such as ceramic. Although the coating element 175 may be made of metal, another insulation or coating material is required for electrical isolation between the lower heater 58 and the coating element 175.

Fig. 35 is a perspective view illustrating the main components including a heater 20 of the heating cooker 1 still a further modification according to the sixth embodiment. As shown in Fig. 35, the heater 20 is housed within a box-shaped air-tight container 70 having a lid member 72 and a container member 74. The airtight box-shaped container 70 functions as an oven or a kettle, and food inside the airtight box-shaped container 70 can be cooked in the oven by heating the lid member 72 and the vessel member 74.

Fig. 36 is a development view of the lower heater 20 housed in the container member 74, which is assembled to form the lower heater by folding upwards on the dashed lines. The upper heater 20 of the cover member 72 is also assembled in a similar manner. The heater 20 includes the low resistivity parts 22 and the high resistivity part 26, in which each of the low resistivity parts has the energy-fed part and the cooling part as described in the previous embodiments. The high resistivity part 26 is formed by perforating a metal plate (for example, stainless steel or aluminum plate) in a shape like that of Fig. 36. Fig. 37 is a cross-sectional view of the sealed container 70 air-shaped box. The cover member 72 includes a cover body 73 of insulation material, such as ceramic, and the high resistivity part 26, and the container member 74 also includes a container body 75 of insulation material and the part 26 of high resistivity too.

The lid body 73 and the container body 75 may be made of metal. But if this is the case, because it is necessary to insulate the high resistivity part 26 of the lid body 73 and the container body 75, a thermal and electrical insulation film, such as a ceramic sheet, must be interposed between the high resistivity part 26 and cover body 73 (and container body 75). When the cover body 73 and the container body 75 are made of aluminum, for example, they can be subjected to anodic oxidation (alumite treatment) to form an alumina layer (a layer of oxidized aluminum) on the surface thereof, thus producing an insulating layer without the need to prepare a separate insulating member at a reasonable cost. When the coils 30 of the heating cooker 1 shown in Fig. 35 are fed with the high frequency current, the heaters 20 provided inside the cover body 73 and the container body 75 are heated by the induction current through them, so that the food inside the air-tight container 70 in the form of a box is heated and cooked. Even in the case where the heating cooker 1 is used as an oven, because the air heated inside the box-shaped air-tight container 70 is 300 degrees C or less, which is less than the melting point of aluminum, cover body 73 and container body 75 can be produced in aluminum at a reasonable cost.

Fig. 38 is a perspective view illustrating the main components including a heater 20 of the heating cooker 1 yet further modified according to the sixth embodiment. As shown in Fig. 38, the upper heater 20 is similar to that in Fig. 2, and the lower heater 58 is similar to that in Fig. 32. Preferably, the upper heater 20 may have the high resistivity portion made from a tube (a hollow bar) since it is generally separated from cooking food. On the other hand, the lower heater 58 may preferably have the part of high resistivity made from a metal plate having a substantial surface area for uniform cooking. The upper and lower heaters can have a configuration (shape, size, position) different from each other, and can be designed as removable, therefore, any type of them can be chosen and replaced by another according to the food to be cooked.

Fig. 39 is a cross-sectional view illustrating a heating cooker 1 of yet another additional modification according to the sixth embodiment. The induction heating cooker 1 of Fig. 39 is similar to one of the third embodiment of Fig. 18 in terms of structure and operation, except that the first one has the coils 30a, 30b provided on the upper wall 12a and below of the bottom wall 12b instead of the side walls 14a, 14b. In other words, although the induction heating means with the coils 30 are described as arranged on the side walls in the previous embodiments, the present invention can be similarly adapted so that the induction heating means are provided on the upper wall 12a and below the lower wall 12b as illustrated in Fig. 39. It is also not necessary to mention again that induction heating means may be provided on the front and rear walls, and the side walls may also include the front and back walls.

As described above, according to the heating cooker 1 of the present invention, the heater is structured as removable, therefore, the easy cleaning feature has been considerably improved and various types of heaters 20 suitable for cooking can be used, thus achieving a multifunctional heating kitchen.

Claims (15)

5 10 fifteen twenty 25 30 35 40 Four. Five 1. A heating system, comprising: a box-shaped heating chamber (10); a heater (20) provided inside said heating chamber (10), wherein said heater (20) is made of a conductive material in an electric loop; a coil (30) provided outside said heating chamber (10); a power circuit for supplying high frequency current with said coil (30) to generate a high frequency magnetic flux; characterized by a magnetic member (34) arranged so that said heater (20) is magnetically interconnected with the high frequency magnetic flux generated by said coil (30), wherein said magnetic member (34) has an opening (36), in which inserts a part (24) of said heater (20). 2. Heating system according to claim 1, wherein said coil (30) and said magnetic member (34) are arranged along a wall comprising said heating chamber (10), and wherein the magnetic flux High frequency causes the induction current flowing through said heater (20). 3. Heating system according to claim 1 or 2, wherein said coil (30) is formed by winding a conductive wire in a flatter configuration, and wherein said magnetic member (34) surrounds a plurality of parts of the conducting wire wound through which the high frequency current flows in the same direction. 4. Heating system according to claim 1 or 2, wherein said coil (30) is formed by winding in spiral a conductive wire around a part of said magnetic member (34). 5. Heating system according to any one of claims 1-4, wherein said magnetic member (34) has a U-shaped cross section, and in which a part (24) of said heater (20) is inserted in the opening (36) of the U-shaped cross section of said magnetic member (34). 6. Heating system according to any one of claims 1-4, wherein said magnetic member (34) has a C-shaped cross section, and in which a part (24) of said heater (20) is inserted in the opening (36) of the C-shaped cross section of said magnetic member (34). 7. Heating system according to any one of claims 1-4, wherein said heater (20) has an energy-fed part (24), and wherein said magnetic member (34) completely surrounds part (24) Powered. 8. Heating system according to any one of claims 1-7, wherein said heater (20) includes a high resistivity part (22) and a high resistivity part (26), and wherein the part (22 ) Low resistivity is magnetically interconnected with the high frequency magnetic flux. 9. Heating system according to claim 8, wherein the part (22) of low resistivity and part (26) of high resistivity are made of solid metal and hollow metal, respectively. 10. Heating system according to claim 8, wherein the part (58) of high resistivity is a metal plate provided with a plurality of cuts (59). 11. Heating system according to claim 10, wherein said heater (20) includes a plate-shaped member that encompasses the high resistivity part (58). 12. Heating system according to claim 10, further comprising a box-shaped container that encompasses the part (58) of high resistivity. 13. Heating system according to claim 8 or 9, wherein the low resistivity part (22) includes a cooling part (25) exposed in the atmosphere inside said heating chamber (10). 14. Heating system according to any one of claims 1-13, wherein said heating chamber (10) is made of metal, and wherein at least one of the interior walls of said heating chamber (10) or said heater (20) is coated with insulating material. 15. Heating system according to any one of claims 1-14, wherein said heater (20) is removably installed inside said heating chamber (10). twenty