Electromagnetic heating device

Abstract

To provide an electromagnetic heating device that is improved in one or more of various points such as miniaturization, improvement of heating speed, efficiency of a cooling mechanism, and measures for contamination around a radiation thermometer.SOLUTION: An electromagnetic heating device 1 includes: a top plate 3 on which a heat storage cooking dish 10 for heating and cooking dished food is placed; and a plate-like IH coil 5 disposed therebelow. The heat storage cooking dish 10 includes a relatively thick base plate 10c having a bottom upper surface 10b that is a food cooking surface and a bottom surface 10j. A plane external size of the IH coil 5 is substantially equal to or smaller than a size of the bottom surface 10j of the heat storage cooking dish 10.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electromagnetic heating device for heating cooking vessels such as iron dishes used in residual heat (heat storage) cooking. In particular, the present invention relates to an electromagnetic heating device that has been improved in various aspects, such as miniaturization, improved heating speed, more efficient cooling mechanism, and measures against dirt around the radiation thermometer. [Background technology]

[0002] The steakhouse chain "Pepper Lunch" (registered trademark) is popular for its style of cooking: it uses an electromagnetic induction heater to heat a heat-retentive iron plate to a high temperature (for example, 290°C), then serves beef and rice on top of it to customers, who then cook the food themselves on the iron plate and eat it fresh.

[0003] Patent Document 1 discloses a heating device having an air nozzle that prevents the temperature sensor (light receiving portion) of the iron plate from becoming dirty with oily smoke or the like. Patent Document 2 discloses a cooking device in which a radiation thermometer for detecting the temperature of an iron plate is disposed inside an air nozzle. Patent Document 3 discloses an iron plate (electromagnetic heating cooking plate) suitable for the above-mentioned "Pepper Lunch" style. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent 3680942 [Patent Document 2] Patent 5796705 [Patent Document 3] Patent 4237739 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0005] The electromagnetic induction heaters described in the above patent documents or currently used electromagnetic induction heaters are excellent, but with an expected increase in the number of new stores in the future, it is desirable to add the following improvements. (1) Compact size of the device body; By reducing the size of the main body, it is possible to add more equipment in a limited installation space. In order to reduce the size of the device, it is also necessary to reduce the size of the coil cooling mechanism and the mechanism for preventing contamination of the temperature sensor. (2)Increased heating speed; By shortening the heating time of the iron plate, in combination with the effect of (1) above, it is possible to speed up the serving of food during peak times, increasing customer turnover and leading to increased profits for the store. (3) Improved cleanliness around the thermometer;

[0006] An object of the present invention is to provide an electromagnetic heating device which is improved in one or more respects, such as miniaturization, increased heating speed, more efficient cooling mechanism, and measures against dirt around the radiation thermometer. [Means for solving the problem]

[0007] In this "Summary" and "Claims," ​​reference signs to various parts in the attached drawings are shown in parentheses, but this is for reference only and is not intended to limit the scope of the rights to those in the attached drawings.

[0008] The first electromagnetic heating device (1) of the present invention is a device for heating a heat storage cooking dish (10) of a specified shape and dimensions, which cooks food placed on it using heat stored by heating, and is characterized in that it comprises a top plate (3) on which the dish is placed, and a plate-shaped IH coil (5) arranged below the top plate, wherein the heat storage cooking dish (10) has a relatively thick base plate (10c) having a bottom upper surface (10b) which is a food cooking surface and a bottom surface (10j) which rests on the top plate (3), and a relatively thin flange portion 10f which rises upward and outward from the periphery, and the planar outer dimensions of the IH coil (5) are substantially equal to or smaller than the dimensions of the bottom surface (10j) of the heat storage cooking dish (10).

[0009] The dimensions of the heat storage cooking dish (iron dish) and the IH coil are as follows: In one example (embodiment), the bottom diameter of the iron dish is 165 mm; The outer diameter of the IH coil is 155 mm. In the conventional example, the outer diameter of the IH coil is 175 mm (10 mm larger than the bottom of the iron plate). The heating time for the iron plate to reach 290°C was 65 seconds for the Example compared to 75 seconds for the Comparative Example, shortening the time by 10 seconds. The output of the IH coil 5 was the same at 5kW for both examples. The iron plate is placed in the center of the IH coil by aligning it with the concentric circle mark on the top surface of the top plate, just like with a general IH cooker.

[0010] The reason why the heating time is significantly shorter in the embodiment is believed to be that the efficiency of electromagnetic induction heating is better when the heat is concentrated on the bottom plate (10c). In one example of the iron plate (10), the thickness of the bottom plate (10c) is 15 mm, the thickness of the flange portion (10f) is 5 mm, the rising angle (θ in the figure) of the flange portion (10f) is about 127°, and the weight is 1500 g. If the electromagnetic induction heating effect can be concentrated on the bottom plate, it may be said that "the planar outer dimension of the IH coil (5) is substantially equal to or smaller than the dimension of the bottom surface (10j) of the heat storage cooking plate (10)" even if the bottom surface of the heat storage cooking plate is slightly larger. The difference in dimensions between the heat storage cooking plate (iron plate) and the IH coil is preferably about 5 to 15 mm when the diameter of the iron plate is 165 mm, and 3 to 9% of the former.

[0011] In the first invention of the present invention, it is possible to shorten the time required to heat the iron plate. In addition, by making the heating coil small to fit the bottom surface (heating area) of the dedicated iron plate, it is possible to reduce material costs, considering that the copper wire used to make the heating coil is relatively expensive. Furthermore, it is possible to aim for a smaller device and an increase in the number of electromagnetic heating devices installed in the store, which will increase customer turnover and lead to increased store profits.

[0012] The second electromagnetic heating device (1) of the present invention comprises a top plate (3) on which an object to be heated (10) is placed, an IH coil (5) disposed below the top plate, and is characterized in that a cooling air guide (7) is provided, the cooling air guide (7) having a bottom plate (75) covering the bottom surface of the IH coil via a gap and side plates (71) covering both side surfaces of the IH coil via a gap, which define a flow path (70) for cooling air to be applied to the IH coil. Here, the IH coil (5) in the broad sense refers to both the coil body and the coil base (53) supporting it.

[0013] In the electromagnetic heating device of the second invention, the width and height of the air passage (70) for the coil cooling air are minimized to match the external shape of the IH coil (5), thereby improving the coil cooling efficiency and making the device more compact. The upper side of the air passage (70) is defined by the lower surface (3f) of the top plate (3). When this second invention is combined with the above-mentioned first invention (small coil), it is possible to further reduce the device size. Furthermore, the improved coil cooling efficiency is expected to improve the coil's service life. The allowable temperature of the IH coil is, for example, 130°C.

[0014] In the second invention, it is preferable that the bottom plate (75) and the pair of left and right side plates (71) are separate bodies, and the side plates (71) are biased into contact with the lower surface (3f) of the top plate (3).

[0015] That is, by separating each wall of the cooling air guide (7) and adopting a biasing (such as a movable spring) of the top plate (3) facing the bottom plate (75), it is possible to ensure the adhesion between the cooling air guide and the top plate and prevent the leakage of cooling air. In a general design in which the cooling air guide is box-shaped, a gap occurs between the cooling air guide and the top plate due to manufacturing accuracy reasons, and the cooling air leaks, which can reduce the cooling efficiency. It would be desirable to adopt a sealing packing made of silicon to seal the above-mentioned gap, but it is expected that the packing will melt due to heat conduction from the iron plate heated on the top plate, so a spring-operated cooling air guide was adopted.

[0016] The third electromagnetic heating device of the present invention comprises a top plate (3) on which an object to be heated (10) is placed; The electromagnetic heating device (1) comprises an IH coil (5) disposed below the top plate, an inverter (6) that supplies high-frequency current to the IH coil (5) and an inverter box (63) that houses the inverter (6) and a main body frame (2) in which the above-mentioned components are disposed, and further comprises a cooling air guide (7) that guides the flow of cooling air to be applied to the IH coil, and a fan (8) that generates cooling air, the fan being a complete set that distributes air into the cooling air guide (7) and toward the inverter box (63).

[0017] By reducing the diameter of the IH coil (5) and creating a coil cooling air passage (70) with as small a gap as possible around it, it is possible to use only one cooling fan (axial fan, etc.), improving the cooling efficiency. Naturally, reducing the cost of the axial fan, which is an electrical component, also leads to a reduction in the labor required for assembly, resulting in the great benefit of being able to reduce initial costs.

[0018] A fourth electromagnetic heating device of the present invention is an electromagnetic heating device (1) comprising: a top plate (3) on which an object to be heated (10) is placed; an IH coil (5) disposed below the top plate; an inverter (6) that supplies high-frequency current to the IH coil (5) and an inverter box (63) that houses the inverter (6); and a fan (8) that generates cooling air to be blown onto the IH coil and / or the inverter, further comprising a radiation thermometer (9) that detects the temperature of the object to be heated (10), a light-receiving part (91) of the thermometer being disposed within a ventilation nozzle (93), and purge air that passes through the nozzle and flows around the light-receiving part (91) is discharged from the fan (8) and distributed to the IH coil (5) and / or the inverter box (63) and then guided thereto.

[0019] In the electromagnetic heating device of the fourth invention, a non-contact infrared sensor is used to measure the temperature of the iron plate from above. However, oily smoke and other substances generated by continuous cooking of the iron plate may adhere to the light receiving part, making it impossible to perform accurate temperature measurement. Therefore, as a measure to prevent the light receiving part of the radiation thermometer from becoming dirty, the light receiving part is surrounded by an air nozzle shape, and a path is provided for the coil cooling air to be sprayed from the nozzle, thereby adopting a structure to prevent the light receiving part from becoming dirty. Note that the wind speed of the cooling air is a light wind of about 3 m / s in the device of the embodiment, which is not enough to cool the iron plate during heating. In addition, the exhaust temperature of the coil cooling air is about 40°C in one example, and considering that the environmental temperature of the radiation thermometer is 70°C or less, it can be used to prevent the light receiving part from becoming dirty.

[0020] Conventional electromagnetic heating devices have a compressor that supplies air for purging the light receiving part of the radiation thermometer 9, but the present invention eliminates the need to install such a compressor, making it possible to further miniaturize the device. The method of preventing dirt from adhering to the light receiving part by forming an air nozzle around the light receiving part of the radiation thermometer is the same as the structure in the above-mentioned Patent Document 2, but the method of air intake is new in that "air is sprayed from the nozzle by utilizing the cooling wind of the coil."

[0021] A fifth electromagnetic heating device of the present invention comprises a top plate (3) on which a heat-storage cooking dish (10) is placed, an IH coil (5) disposed below the top plate, an inverter (6) that supplies high-frequency current to the IH coil (5), and a control unit for the inverter, After the heat storage cooking dish has been heated up to a target temperature, the output of the inverter is reduced to a predetermined level between 10% and 20%, thereby keeping the heat storage cooking dish warm. Effect of the Invention

[0022] The present invention provides one or more of the following effects. (a) By making the coil smaller, the heating efficiency is improved, allowing the coil and coil base to be made smaller. (a) By selecting an IH coil that is suitable for the dimensions of the heat storage cooking dish (iron dish), the heating time of the iron dish can be shortened. (c) The cooling air passage can be minimized, improving the coil cooling efficiency. (d) By making the cooling air guide separate and spring movable, it is possible to ensure close contact between the top plate and the cooling air flow path component, and to prevent leakage of cooling air from the contact area. (E) By improving the coil cooling efficiency, the coil's service life can be improved.

[0023] (f) The coil and inverter box can be cooled using just one axial fan. (g) Initial costs can be reduced by using a single axial fan, or by reducing the size of the coil, and by eliminating the compressor for purging air for the radiation thermometer. (H) A structure can be provided that prevents the adhesion of dirt to the light receiving part of the radiation thermometer installed inside the air nozzle by utilizing the coil / inverter cooling air. (I) It is possible to install many electromagnetic heating devices in a limited space within a store, and by shortening the heating time of the iron plates, customer turnover increases, leading to increased store profits. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 shows the overall configuration of an electromagnetic heating device (iron plate heater) 1 according to an embodiment of the present invention, where (A) is a schematic side cross-sectional view, (B) is a schematic plan cross-sectional view, and (C) is a schematic front cross-sectional view. [Diagram 2] 2 is an enlarged front cross-sectional view showing the periphery of an IH coil 5, a cooling air guide 7, and the like in the electromagnetic heating device 1 of FIG. 1. [Diagram 3] 2A is an enlarged view of the radiation thermometer and its surroundings of the electromagnetic heating device 1 in FIG. 1, in which (A) is a side cross-sectional view of a light receiving unit 91, a nozzle 93, and a post 96, and (B) is a perspective view of a cooling air collecting passage 99. [Explanation of symbols]

[0025] 1; electromagnetic heating device; 2; main body frame; 24; frame; 29; legs 3; top plate, 3f; bottom 5; IH coil, 53; coil base, 55; pin 6; inverter, 63; inverter box 7; cooling air guide, 70; flow path (cooling air flow path), 71; Side plate, 71b; Upper flat part, 71f; Vertical plate part, 71j; Lower plate part, 71p; Hole 75; bottom plate, 75f; tapered section, 75g; inclined plate, 76; pin 8; fans, 89; filters 9; radiation thermometer, 91; light receiving part, 93; ventilation nozzle, 93f; tapered part, 93j; nozzle hole 95; head, 96; post 99; cooling air collection passage, 99b; front side, 99d; bent portion, 99f; rear portion 10; Heat storage cooking plate (iron plate, heated object), 10b; Bottom top surface, 10c; Bottom plate, 10f; Flange part, 10j; Bottom surface DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. In each drawing, the directions "up" and "down" indicated by the arrows are directions along the earth's gravity. "Front" is the side where the cook stands and places and removes the iron dish 10. "Back" is the opposite, farther direction as seen from the cook. "Left" and "right" are the left and right directions as seen by the cook facing the electromagnetic heating device 1.

[0027] First, with reference to FIG. 1, the overall structure of an electromagnetic heating device 1 according to an embodiment of the present invention will be described. The electromagnetic heating device 1 is mainly composed of a main body frame 2 (with legs 29, see Fig. 1(C)) which is generally in the shape of a square box. A top plate 3 on which an object to be heated (a cooking dish, a special iron dish 10) is placed is attached to the center of the upper surface of the main body frame 2. The top plate 3 is generally made of heat-resistant glass.

[0028] An IH coil 5 is disposed below the top plate 3. The IH coil 5 is made of copper wire wound in a circular shape when viewed from above. The IH coil 5 is placed on a resin coil base 53 (circular when viewed from above). The sides and bottom of the IH coil 5 and coil base 53 are covered by a cooling air guide 7. Cooling air is sent into the cooling air guide 7 from a fan 8 on the front side of the main body frame 2. Details of the IH coil 5, coil base 53, and cooling air guide 7 will be described later with reference to FIG. 3.

[0029] An inverter box 63 is disposed below the IH coil 5 within the main body frame 2. The box 63 houses an inverter 6 that supplies high-frequency current to the IH coil 5. The inverter 6 is composed of power semiconductor elements and a capacitor disposed on a board. The cooling mechanism for the inverter 6 will be described in detail later.

[0030] A radiation thermometer 9 is disposed on the upper surface at the rear of the main body frame 2 of the electromagnetic heating device 1. The radiation thermometer 9 has structures such as a pillar 96 erected on the upper surface of the main body frame 2, a head 95 at the top of the pillar, and a nozzle 93 protruding downward on the front side of the pillar. A light receiving unit 91 is disposed inside the nozzle 93. The light receiving unit 91 faces the center of the iron dish 10 placed on the top plate 3, and detects infrared rays emitted from the iron dish 10. The strength of the detected infrared rays is then converted into a temperature based on a coefficient adjusted in advance. The contamination prevention mechanism of the radiation thermometer 9 (air blowing from the nozzle) will be described later.

[0031] The iron plate 10 is basically of the same shape, size, and material, exclusive to each store in which the electromagnetic heating device 1 is installed. In this embodiment, it is a high heat storage iron plate disclosed in Patent Document 3, exclusive to the steak house chain "Pepper Lunch" (registered trademark). The dimensions are 165 mm in bottom diameter, 1500 g in weight, and the material is magnetic stainless steel + cast iron + aluminum alloy. The iron plate 10 has a relatively thick base plate 10c with a bottom upper surface 10b, which is the food cooking surface, and a bottom surface 10j that rests on the top plate 3, and a relatively thin flange portion 10f that rises upward and outward from the periphery.

[0032] IH coil 5 is made of copper stranded wire, and both ends of the coil are connected to inverter 6. When a current is passed through coil 5, magnetic lines of force are generated, and when these magnetic lines of force pass through inclined bottom plate 13, eddy currents are generated, and these eddy currents are converted into heat by electrical resistance and heat the bottom plate (induction heating).

[0033] Next, the miniaturization of the IH coil 5 (appropriate dimensions to match the characteristics of the dedicated iron plate 10), which is one of the features of the electromagnetic heating device 1 of this embodiment, will be described. That is, the electromagnetic heating device 1 of this embodiment includes a top plate 3 on which a heat-storage cooking plate (iron plate 10) of a predetermined shape and size is placed, which cooks food placed on it with heat stored by heating, and a plate-shaped IH coil 5 disposed below the top plate.

[0034] The planar outer dimensions of the IH coil 5 are substantially equal to or smaller than the dimensions of the bottom surface 10j of the heat storage cooking dish 10. In a specific example, the diameter of the bottom surface 10j of the iron dish is 165 mm, and the outer diameter of the IH coil 5 is 155 mm. The coil is one size smaller. This allows for concentrated heating of the bottom of the plate, shortening the heating time to 290°C from the previous 75 seconds to 65 seconds. The diameter of the coil in the previous device is 175 mm. In this way, the heating coil has been made smaller to match the bottom surface (heating area) of the dedicated iron plate. Considering the price of copper wire, which is the material of the heating coil, the cost of materials can be reduced by manufacturing it compactly. The coil base has also been made smaller.

[0035] Next, the cooling mechanism of the IH coil 5 will be described mainly with reference to FIG. Fig. 2 is an enlarged front cross-sectional view showing the IH coil 5, the cooling air guide 7, and the surroundings in the electromagnetic heating device 1 of Fig. 1. The cooling air guide 7 and the coil base receiver (bottom plate 75) are provided above the inverter box 63 to improve the coil cooling efficiency.

[0036] The electromagnetic heating device 1 of this embodiment is provided with a cooling air guide 7 that surrounds the left, right, and bottom of the IH coil 5. That is, the cooling air guide 7 has a bottom plate 75 that covers the bottom surface of the IH coil 5 (coil base 53) via a certain gap, and side plates 71 that cover both the left and right side surfaces of the IH coil 5 via certain gaps. The space surrounded by the bottom plate 75, the side plates 71, and the bottom surface 3f of the top plate 3 forms a cooling air flow path 70.

[0037] The gap s between the inner surface of the side plate 71 and the outer surface of the coil 5 is 10 mm. The diameter of the coil 53 is 165 mm, and the gap between its outer surface and the inner surface of the side plate 71 is 5 mm. The gap h1 between the upper surface of the coil base 53 and the lower surface 3f of the top plate 3 is 10 mm. The gap h2 between the lower surface and the upper surface of the bottom plate 75 is 10 mm. 55. The dimensions of these gaps are suitable for sufficient coil cooling while keeping the dimensions of the cooling airflow path 70 as small as possible. The height of the cooling airflow path directly below the coil base is 10 mm, and cooling efficiency is improved by concentrating the cooling air over the top surface of the coil and the bottom surface of the coil base. The spatial distance between the top plate and the inverter box is 50 mm to avoid the effects of radiant heat from the iron plate, which heats up on the top plate and reaches a temperature of approximately 290°C.

[0038] As seen in the side cross-sectional view of FIG. 1(A), an inclined plate 75g is disposed on the rear side of the fan 8. The inclined plate 75g is an inclined plate that is lower on the front side and higher on the rear side. As seen in FIG. 1(B), the width of the inclined plate 75g is approximately the same as the width of the fan 8. The front lower end of the inclined plate 75g is located at the rear lower end of the fan 8, and the rear upper end is connected to the front lower end of the tapered portion 75f. This inclined plate 75g adjusts the direction of the air discharged by the fan 8. Most is led to a cooling air flow path 70 of the IH coil 5.

[0039] 1(A), the front edge of the bottom plate 75 forms a tapered section 75f, which smoothly guides the air from the axial fan 8 into the cooling air flow path 70. The cooling air that enters the coil cooling air flow path 70 from the tapered section 75f passes mainly above and below the IH coil 5 and the coil base 53, and is discharged from the back side of the passage 70. No cooling air is sent between the lower surface of the bottom plate 75 and the upper surface of the inverter box 63.

[0040] The exhaust air, which is a part of the cooling air that has passed through the coil 5, passes through the cooling air collection passage 99 at the rear left, rises up the column of the radiation thermometer 9, passes through the head 95, and passes through the inside of the nozzle 93, and is discharged downward toward the front. FIG. 3(B) is a perspective view of the cooling air collection passage 99 that guides the air from the cooling air flow path 70 to the inside of the column 96 of the radiation thermometer 9. The front side portion 99b of the collection passage 99, which is an L-shaped sheet metal guide, opens on the front side, extends to the rear, bends to the left (bent portion 99d), and extends to the left and hits (rear portion 99f). The air bends upward from the rear portion 99f and enters the column of the radiation thermometer 9. This cooling air collection passage 99 allows the coil cooling air to be efficiently blown to the nozzle portion of the radiation thermometer 9 (infrared sensor).

[0041] A light receiving unit 91 including a light receiving element is disposed in the center of the base 93b of the nozzle 93. The front side of the nozzle 93 is tapered to a narrowed portion 93f, and a nozzle hole 93j is opened at the tip. Air that flows downward around the outer periphery of the light receiving unit 91 is ejected from the nozzle hole 93j in front of the light receiving unit 91. This ejected air prevents oily smoke and dust rising from the iron plate 10 from hitting the light receiving unit 91.

[0042] The air coming out from the fan 8 to the rear side is also separated to the left and right outside, cooling the left and right side walls of the inverter box 63. There is an opening (not shown) at the rear of the inverter box 86, which allows the amount of ventilation inside to be adjusted. Heat generated by the power semiconductors and other components inside the box is exhausted from the rear side of the main body frame 2 together with the cooling air.

[0043] An axial flow fan 8 is provided in front of the electromagnetic heating device 1. Filter 89 are arranged. Fan 8 sends cooling air from the front side to the back side. The diameter (vertical dimension) of fan 8 roughly corresponds to the sum of the height of IH coil 5 and the height of inverter box 63. The lateral dimension of fan 8 is slightly smaller than that of cooling air guide 7. The lateral center of fan 8 roughly coincides with the lateral center of cooling air guide 7. The upper part of the air coming out of fan 8 is sent to IH coil 5. The lower part of the air coming out of fan 8 is sent to inverter box 63.

[0044] The power of the axial fan 8 is 9W, and the capacity of the IH coil 5 is 5kW. One axial fan 8 is enough to cool the IH coil 5 and inverter 6. Conventional products use two 9W axial fans to cool a 5kW IH coil 5. In comparison, this helps reduce the initial costs of the axial fans and IH coil.

[0045] Another feature of the cooling air guide 7 of this embodiment is that the bottom plate 75 and the pair of left and right side plates 71 are separate bodies, and the side plates 71 are biased against and in contact with the top plate 3. That is, the cooling air guide 7 is not an integrated box (a frame with three sides integrated), but each side, the bottom plate 75, the left and right side plates 71, are separate and independent (not connected, separate) plates. The left and right side plates 71 are biased against and in contact with the bottom surface of the top plate 3 by two coil springs 77 in the back-to-front direction, respectively. This allows the upper plate 71b of the side plate 71 to freely rotate in the back-to-front direction and to follow the bottom surface of the top plate 3. This ensures close contact between the cooling air guide and the top plate, preventing leakage of cooling air.

[0046] The side plate 71 of this embodiment is composed of an upper flat portion 71b, a vertical plate portion 71f, and a lower plate portion 71j from the top. These portions are made by bending sheet metal. The upper flat portion 71b abuts against the lower surface 3f of the top plate 3. Between the vertical plate portions 71f of the left and right side plates 71, a bottom plate 75 is arranged so as to be vertically slidable. The lower plate portion 71j overlaps the lower left and right ends of the bottom plate 75. The lower plate portion 71j has a hole 71p through which a pin 76 passes. The pin 76 supports the bottom plate 75. A coil spring 77 is fitted around the outer periphery of the pin 76 with a gap therebetween. The coil spring 77 presses the side plate 71 against the top plate 3. The lower ends of the pin 76 and the coil spring 77 are supported by the frame middle plate 24. The frame middle plate 24 is a plate that divides the inside of the main frame 2 into upper and lower portions.

[0047] In a general design, due to manufacturing accuracy reasons, there is a risk that the side plate 71 will tilt toward the front from the bottom surface of the top plate 3 due to processing errors and assembly errors of the integrally bent side plate 71 and bottom plate 75, resulting in a gap between the contact area between the two. Therefore, in this embodiment, a structure is devised in which a spring pushes up the lower part of the cooling air guide. Although it would be desirable to use a silicon sealing packing or the like in the above gap, it is anticipated that the packing will melt due to heat conduction from the iron plate heated on the top plate, so a spring-operated cooling air guide is adopted.

[0048] In this embodiment, the cross-sectional area of ​​the cooling air guide 7 (cooling air flow path 70) is kept to a minimum, and the flow rate of the cooling air can be increased (approximately 5 m / sec). In addition, leakage loss of the cooling air can be eliminated. This has the effect of improving the coil cooling efficiency and thus improving the coil service life. The allowable temperature of the IH coil is, for example, 130°C.

[0049] In the electromagnetic heating device of this embodiment, after the heat storage cooking dish 10 has risen to the target temperature, the inverter output is reduced to a predetermined level between 10% and 20% to keep the heat storage cooking dish warm and reduce the drop in dish temperature.

Claims

1. The device heats a heat-storage cooking dish (10) of a specified shape and size, and uses heat stored in the dish to cook food placed on the dish, comprising: A top plate (3) on which the dish is placed; A plate-shaped induction coil (5) disposed below the top plate; Equipped with the heat-storage cooking dish (10) has a relatively thick base plate (10c) having a bottom upper surface (10b) which is a food cooking surface and a bottom surface (10j) which rests on the top plate (3), and a relatively thin flange portion 10f which rises upward and outward from the periphery of the base plate (10c); The electromagnetic heating device (1) is characterized in that the planar outer dimensions of the IH coil (5) are substantially equal to or smaller than the dimensions of the bottom surface (10j) of the heat storage cooking dish (10).

2. The electromagnetic heating device (1) according to claim 1, characterized in that the shape of the bottom surface (10j) of the heat storage cooking dish (10) and the planar shape of the IH coil (5) are circular, and the diameter of the latter is 3 to 9% smaller than the diameter of the former.

3. 3. The electromagnetic heating device (1) according to claim 1 or 2, characterized in that a cooling air guide (7) is provided having a bottom plate (75) covering the bottom surface of the IH coil via a gap, and side plates (71) covering both side surfaces of the IH coil via gaps, which define a flow path (70) for cooling air to be applied to the IH coil (5).

4. A top plate (3) on which an object to be heated (10) is placed; An induction coil (5) disposed below the top plate; An electromagnetic heating device (1) comprising: The electromagnetic heating device is characterized in that a cooling air guide (7) is provided, the cooling air guide having a bottom plate (75) covering the bottom surface of the IH coil via a gap, and side plates (71) covering both side surfaces of the IH coil via gaps, the bottom plate (75) defining a flow path (70) for cooling air to be applied to the IH coil.

5. the bottom plate (75) and the pair of left and right side plates (71) are separate bodies, 5. The electromagnetic heating device according to claim 4, wherein the side plate (71) is biased against and abuts on the lower surface (3f) of the top plate (3).

6. A top plate (3) on which an object to be heated (10) is placed; An induction coil (5) disposed below the top plate; an inverter (6) that supplies high-frequency current to the IH coil (5) and an inverter box (63) that houses the inverter (6); A main body frame (2) in which the above-mentioned components are arranged; An electromagnetic heating device (1) comprising: Further, the cooling apparatus includes a cooling air guide (7) for guiding the flow of cooling air to be applied to the IH coil, and a fan (8) for generating cooling air. The electromagnetic heating device is characterized in that the fan is a set that distributes air toward the inside of the cooling air guide (7) and toward the inverter box (63).

7. A top plate (3) on which an object to be heated (10) is placed; An induction coil (5) disposed below the top plate; an inverter (6) that supplies high-frequency current to the IH coil (5) and an inverter box (63) that houses the inverter (6); A fan (8) that generates cooling air to be blown onto the IH coil and / or the inverter, Further, a radiation thermometer (9) is provided for detecting the temperature of the object to be heated (10), The light receiving portion (91) of the thermometer is disposed in the ventilation nozzle (93), The purge air passing through the nozzle and flowing around the light receiving portion (91) is derived from the wind that leaves the fan (8) and is distributed to the IH coil (5) and / or the inverter box (63).

8. A top plate (3) on which a heat storage cooking dish (10) is placed; An induction coil (5) disposed below the top plate; an inverter (6) that supplies high-frequency current to the IH coil (5); A control unit of the inverter; An electromagnetic heating device (1) comprising: An electromagnetic heating device characterized in that after the heat storage cooking dish has been heated to a target temperature, the output of the inverter is reduced to a predetermined level between 10% and 20%, thereby keeping the heat storage cooking dish warm.

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