JP2013137938A - Induction heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating cooker including a plate which has an excellent temperature distribution and excellent high temperature properties with a simple inverter configuration, and which has a large cooking area.SOLUTION: In an induction heating cooker, when a plate 1 where a cooking object is placed on a top face and cooking is performed is heated, control means 23 alternately drives first and second heating coils 10, 11 by exclusively supplying high-frequency power with a predetermined period and at a predetermined ratio from first and second inverters 14, 15 to a heating coil 10 arranged under a central part of a top plate 3 and second heating coils 11 provided on both sides of the first heating coil 10, which are opposed to each other and connected in series with each other.

Description

  The present invention relates to an induction heating cooker used in a general household kitchen or a commercial kitchen.

  In recent years, induction heating cookers have been applied to various cookers because of their superior characteristics of safety, cleanliness, and high efficiency, as well as the ability to directly heat the load pans and plates themselves. Various plates for pottery are also on sale. In addition, as for thermal power, products with high thermal power of 1400 W are mainstream at 100 volts of ordinary households.

  A general configuration of a conventional induction heating cooker will be described with reference to FIG. As shown in the figure, a top plate 41 made of a heat-resistant insulating plate is provided on the upper portion of the main body 40, and the plate 42 is placed on the top plate 41. Inside the main body 40, there are 43 heating coils having a circular shape that is relatively easy to manufacture, most of which have an outer diameter of about 180 mm, and 44 drive circuit sections are also arranged in the main body 40.

  In the induction heating cooker configured as described above, the drive circuit unit 44 converts the alternating current power into direct current, supplies high frequency current to the heating coil 43, and induction heats the plate 42.

  Also, first and second heating coils for heating the ceramic plate, first and second inverter circuits for supplying a high-frequency current to the first and second heating coils, and the first and second inverters A divider for controlling the supply of high-frequency current from the circuit at a constant cycle and at an arbitrary ratio is provided, and the duty control cycle of the first and second inverter circuits according to the input power value from the power source Or reducing the temperature ripple by increasing or decreasing the duty control period of the first and second inverter circuits according to the temperature fluctuation range of each of the plates (for example, Patent Documents). 1).

  Moreover, the plate which cooks, the 1st heating coil arrange | positioned under the center part of the plate, the 2nd and 3rd heating coil provided in the both sides of the 1st heating coil, and high frequency current to each heating coil Induction heating cooking having a first, second and third inverter circuits to be supplied, and a drive circuit unit having a distribution device for duty-controlling the presence / absence of high-frequency current supply from each inverter circuit at a constant cycle It has also been devised that the total time for supplying the high-frequency current to the second and third heating coils is made longer than the time for supplying the high-frequency current to the first heating coil (for example, Patent Document 2).

JP 05-166579 A JP 09-190879 A

  However, in the configuration of the conventional general induction heating cooker described above, when a large plate is placed on the top plate, the area that can be heated to a high temperature is almost directly above the heating coil, so that uneven baking occurs, and the I couldn't cook.

  In addition, in the configuration of the induction heating cooker described in Patent Document 1, the duty of the two heating coils is controlled, and the duty control periods of the first and second inverter circuits are increased or decreased according to the input power value from the power source. Because the duty control cycle of the first and second inverter circuits is increased or decreased according to the temperature fluctuation range of each plate, a plate with a large cooking area that can perform high-performance temperature control with less temperature ripple However, since two heating coils were provided, the plate wide area could be heated to a high temperature. However, the two heating coils generally have the same shape and are arranged symmetrically from the center of the plate, so that the temperature distribution is the best, and because one side is heated by duty control, compared to directly above each heating coil The temperature at the outer peripheral part of the cooking surface of the plate and the boundary between the two heating coils is low, and uneven baking tends to occur.

  Moreover, in the structure of the induction heating cooking appliance of patent document 2, it is to the 1st heating coil arrange | positioned under the center part of a plate, and the 2nd and 3rd heating coil provided in the both sides of the 1st heating coil. By controlling the distribution of the high-frequency current, the temperature distribution was improved compared to the prior art even when a plate with a large cooking area was used, but an inverter circuit was required for each of the first to third heating coils. Therefore, it is necessary to have enough space, and it is necessary to consider component cooling, and it is difficult to downsize the board. Furthermore, since the first to third heating coils operate in order, the temperature distribution is difficult to be symmetrical with respect to the center of the plate.

  An object of the present invention is to solve the conventional problems described above, and to provide an induction cooking device that simplifies an inverter and has a good temperature distribution over a wide area even on a plate having a large cooking area.

  In order to solve the above-described conventional problems, an induction heating cooker according to the present invention includes a plate for cooking by placing an object to be cooked on an upper surface, a top plate on which the plate is placed, and a lower center portion of the top plate. A first heating coil arranged on both sides of the first heating coil, a second heating coil provided opposite to both sides of the first heating coil, the coils on both sides being connected in series, and rectification for converting the AC power source into DC A circuit, a switching element and a resonant capacitor, and a first and a second inverter for supplying high-frequency power to the first and second heating coils, respectively; and a high-frequency power from the first and second inverters And when the plate is heated, the control means controls the first and second heating controllers from the first and second inverters. The supply of RF power to the Le exclusively performed that a predetermined cycle and a ratio is obtained by forming the first and the second heating coil to drive alternately.

  Thereby, it is possible to provide an induction heating cooker that has a good temperature distribution and a symmetrical temperature over a wide area of the plate in a plate having a large cooking area, while simplifying the inverter.

The perspective view of the induction heating cooking appliance in the 1st Embodiment of this invention AA sectional view of an induction heating cooking appliance in a 1st embodiment of the present invention. The perspective view of the 1st and 2nd heating coil in the 1st Embodiment of this invention The circuit diagram of the induction heating cooking appliance in the 1st Embodiment of this invention The figure which shows the example of the heating pattern in the 1st Embodiment of this invention The figure which shows the direct heating part of the heating coil in the 1st Embodiment of this invention The figure which shows the usage example of the induction heating cooking appliance in the 1st Embodiment of this invention Operation explanatory diagram of a conventional induction heating cooker

  The first invention includes a plate for cooking by placing an object to be cooked on an upper surface, a top plate on which the plate is placed, a first heating coil disposed below the center of the top plate, and the first The heating coil includes a second heating coil provided opposite to both sides of the heating coil, the coils on both sides being connected in series, a rectifier circuit that converts AC power into DC, a switching element, and a resonance capacitor. A first and a second inverter for supplying high-frequency power to the first and second heating coils, respectively, and a control means for controlling the supply of the high-frequency power from the first and second inverters; When heating the high frequency power from the first and second inverters to the first and second heating coils by the control means, a predetermined cycle and ratio In exclusively perform it is obtained by forming the first and the second heating coil to drive alternately.

  Thereby, it is possible to heat a plate having a large cooking area with a simple configuration of one rectifier circuit and two inverters so that the temperature distribution is symmetrical and substantially uniform over a wide range.

  Further, the plate is removed, a load such as a pan or a frying pan is placed at the center of the top plate, and high-frequency power is supplied only to the first heating coil to perform boiling or frying in a frying pan. be able to.

  In the second invention, in particular, in the first invention, the first heating coil is substantially circular, and the second heating coil is substantially elliptical.

  As a result, the substantially circular coil is relatively easy to manufacture compared to other shapes, and the manufacturing cost can be reduced. In addition, when the pan or frying pan is heated by removing the plate, Since most of the bottom of the frying pan is substantially circular, there is little loss and heating can be performed with high efficiency.

  In addition, by making the second heating coil substantially oval, the distance between the outer periphery of the plate and the outer periphery of the heating coil can be shortened rather than using a heating coil with a substantially circular shape, so that the plate is heated over a wide area. The temperature unevenness of the plate can be suppressed.

  In particular, according to a third invention, in the first or second invention, the coil constants including the plates of the first and second heating coils are substantially the same.

  As a result, a resonant capacitor having a capacity selected corresponding to the resonant frequency of the plate can be shared by the first and second inverters, so that costs can be reduced and there is no mistake in mounting on the substrate.

  In a fourth aspect of the present invention, in particular, in any one of the first to third aspects, a temperature sensor that senses the temperature of the plate is provided around each of the first and second heating coils, and a difference in sensing temperature is constant. When the value exceeds the value, the power supply rate to the first or second heating coil having a low sensed temperature is increased, and the sensed temperature difference is controlled to be a certain value or less.

  Thereby, even if the food is put on the plate and the temperature is partially lowered, it can be immediately returned to the predetermined temperature, and the user can feel a high thermal power even during continuous cooking.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, when the plate is preheated, only the first heating coil is driven, and after the temperature of the plate reaches the first predetermined temperature, The heating coil is driven alternately until the second predetermined temperature is reached while the driving ratio of the heating coil is set to be at least twice as large as that of the first heating coil.

  As a result, the first heating coil disposed in the central portion has less heat loss than the second heating coil close to the outer periphery of the plate, so that the temperature of the plate can be increased in a short time. It can be done.

  In a sixth aspect of the invention, in particular, in the fourth aspect of the invention, the temperature of the central portion of the plate is about 200 ° C., and the temperature in the vicinity of the left and right outer peripheral portions of the plate is about 100 ° C. 2 heating coils are controlled.

  Thereby, while cooking grilled meat etc. in the center part of the said plate, it can heat-retain in the right-and-left part of a plate, and can always eat a cooked food in a warm state.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiment. In addition, the description order of the embodiments may be different from the order of the invention described above. Note that components that are unnecessary for the description of the embodiment are omitted even if they are main components.

(Embodiment 1)
1 is a perspective view of an induction heating cooker according to the first embodiment of the present invention, FIG. 2 is a cross-sectional view of the induction heating cooker according to the first embodiment of the present invention, taken along line AA, and FIG. 3 is a book. The perspective view of the 1st and 2nd heating coil in the 1st Embodiment of invention, FIG. 4 shows the circuit diagram of the induction heating cooking appliance in the 1st Embodiment of this invention.

  1, 2, and 3, the plate 1 is made of a substantially rectangular magnetic material for cooking, and a food is placed on the cooking surface 2 for cooking. The top plate 3 is made of a ceramic flat plate, the upper part 4 of the main body is made of a high heat-resistant resin exceeding 200 ° C. such as PET resin, and the top plate 3 is silicon at the flat peripheral edge 5 of the upper part 4 of the main body. It is fixed with a heat-resistant adhesive 6 such as resin. A control board 8 and a heating coil support 9 are attached to the upper surface of the lower body 7 fixed to the upper body 4 by screws from the bottom.

  On the heating coil support 9, a first heating coil 10 is provided at a position below the central portion of the plate 1, and second heating coils 11 are provided on opposite sides of the first heating coil 10. The heating coils 11 are connected in series.

  The first heating coil 10 is substantially circular and has a diameter of about 170 mm. The second heating coil 11 is substantially elliptical, and has a major axis of about 180 mm and a minor axis of about 65 mm.

  Further, temperature sensors 12a and 12b such as thermistors are provided on the first and second heating coils 10 and 11, respectively.

  Further, as shown in FIG. 4, the control board 8 disposed on the upper surface of the lower part 7 of the main body has a rectifier circuit 13 that converts the supplied AC power supply (commercial power supply) 22 into DC, and the output of the rectifier circuit 13 is a high frequency signal. First and second inverters 14 and 15 for supplying electric power to the first and second heating coils 10 and 11 are provided. The first and second inverters 14 and 15 are provided with a first switching element 16, a second switching element 17, a first resonance capacitor 18, and a second resonance capacitor 19, respectively. The operating frequency is changed with respect to the resonance frequency determined by the inductance of the heating coil in the state of being placed on the plate 3 and the capacitance of the first resonance capacitor 18 and the second resonance capacitor 19, resulting in a predetermined input current. The switching element is controlled as follows.

  In the present embodiment, resonance capacitors 18 and 19 having substantially equal capacities are used to adjust the winding dose of the heating coil and the length and amount of a ferrite core (not shown) provided in the vicinity of the heating coil. Thus, the inductance values of the first and second heating coils 11 in a state where the plate 1 is placed are adjusted. Since the resonance capacitors having the same capacity are used, the cost can be reduced and there is no mistake in mounting on the control board 8.

  The operation and action of the cooking device configured as described above will be described below.

  FIG. 5 is a diagram showing an example of a heating pattern in the first embodiment of the present invention, FIG. 6 is a diagram showing a direct heating part of the heating coil in the first embodiment of the present invention, and FIG. It is a figure which shows the usage example of the induction heating cooking appliance in 1st Embodiment.

  When a user performs plate cooking, the user places the plate 1 on the top surface of the top plate 3, selects a set temperature from the operation unit 20, and starts the plate. High-frequency power is supplied to the first and second heating coils 10 and 11 from the first and second inverters 14 and 15 at predetermined cycles and ratios that differ depending on the set temperature. Since the first and second heating coils 10 and 11 generate a high-frequency magnetic field by high-frequency power, eddy current is generated in the plate 1 placed above, and the plate 1 generates heat due to its own skin resistance and eddy current. , The temperature rises.

  In the present embodiment, as shown in FIG. 5A, when the plate 1 is preheated, first, the high frequency power is set to be supplied only to the first heating coil 10. Since the first heating coil 10 disposed in the center portion has less heat loss than the second heating coil close to the outer periphery of the plate 1, the temperature of the plate 1 can be increased in a short time. When the temperature of the plate 1 reaches about 70 to 80% of the set temperature (time T1), supply of high-frequency power to the second heating coil 11 is started. Since the high-frequency power is alternately supplied to the first and second heating coils 10 and 11 at a predetermined cycle and ratio, the respective heating coils are not heated at the same time. Thereby, generation | occurrence | production of the unpleasant audible sound which arises from the shift | offset | difference of the operating frequency concerned when it heats simultaneously can be prevented.

  When the temperature of the plate 1 reaches the set temperature determined by the user, a buzzer sound is emitted to notify the user, and the first heating coil 10 and the second heating are performed so that the entire area of the plate 1 can be kept warm. The coil 11 is alternately heated at a predetermined cycle and ratio as shown in FIG.

  As shown in FIG. 6, the first heating coil 10 has a substantially circular shape, and the second heating coil has a substantially elliptical shape. Therefore, indirect heating by the heating coil is more than when the central and left and right heating coils are all circular. Since there are few parts, it is easy to control the temperature distribution of the plate 1 over a wide area. In addition, although it is also conceivable that the second heating coil has four small circular heating coils on the left and right sides and is connected in series, the induction heating cooker of the present embodiment However, since the number of coils increases and the number of assembly steps also increases, there is a concern about cost increase.

  When the user starts cooking on the plate 1, the temperature of the surrounding plate 1 where the food is baked decreases. The temperature sensors 12a and 12b provided in the first and second heating coils 10 and 11 sense a temperature drop, and sense a low temperature when the difference between the sensed temperatures of the temperature sensors 12a and 12b exceeds a predetermined value. Increase the supply ratio of high-frequency power to the heating coil, and continue until the sensed temperature difference is below a predetermined value.

  In this configuration, as shown in FIG. 7, the plate 1 is removed, a load 21 such as a pan or a frying pan is placed at the center of the top plate 3, and high frequency power is supplied only to the first heating coil 10. It is possible to perform boiling water or frying with a frying pan at a high heating power of about 1400 W, and it can also be used as a desktop type IH.

  That is, only when cooking using the plate 1, the first and second heating coils 10 and 11 are operated alternately, the plate 1 is removed, and cooking is performed on the top plate 3 with a load 21 such as a pan or a frying pan. When performing, only the 1st heating coil 10 is operated, and there is no waste. In the present embodiment, the plate can be heated with a good temperature distribution symmetrically over a wide area with such a simple configuration, and a pan and a frying pan can also be heated with high heating power and high efficiency.

(Embodiment 2)
Since the basic configuration of the present embodiment is almost the same as that of the first embodiment, only different points will be described below.

  The operation unit 20 has a “cooking / warming mode”. When the user selects this mode, cooking can be performed at the left and right sides while cooking at the center of the plate 1. Specifically, the first and second heating coils 10 and 11 are controlled so that the temperature at the center of the plate 1 is about 200 ° C. and the temperature near the left and right outer peripheral portions of the plate 1 is about 100 ° C.

  Thereby, for example, the left and right portions of the plate 1 can be kept warm while cooking grilled meat or the like at the center of the plate 1, and the cooked food can be eaten in a warm state at any time.

  As described above, the heating cooker according to the present invention enables plate cooking with excellent temperature distribution with a simple inverter configuration, and can be applied to built-in, stationary, tabletop induction heating cookers, and the like.

DESCRIPTION OF SYMBOLS 1 Plate 2 Cooking surface 3 Top plate 4 Main body upper part 5 Peripheral part 6 Heat resistant adhesive 7 Main body lower part 8 Control board 9 Heating coil support stand 10 1st heating coil 11 2nd heating coil 12a, 12b Temperature sensor 13 Rectification circuit DESCRIPTION OF SYMBOLS 14 1st inverter 15 2nd inverter 16 1st switching element 17 2nd switching element 18 1st resonance capacitor 19 2nd resonance capacitor 20 Operation part 21 Loads, such as a pan and a frying pan 22 AC power supply 23 Control means 30 1st heating coil heating part 31 2nd heating coil heating part 32 1st and 2nd heating coil non-direct heating part

Claims (6)

A plate for cooking by placing an object to be cooked on the upper surface, a top plate for placing the plate, a first heating coil disposed below the center of the top plate, and on both sides of the first heating coil The first and second second coils are configured to include a second heating coil that is provided opposite to each other and in which coils on both sides are connected in series, a rectifier circuit that converts AC power into DC, a switching element, and a resonant capacitor. When heating the plate, the first and second inverters for supplying high-frequency power to the heating coils, respectively, and control means for controlling the supply of high-frequency power from the first and second inverters. The control means exclusively supplies high-frequency power from the first and second inverters to the first and second heating coils at a predetermined cycle and ratio. And, the induction heating cooker comprising the first and the second heating coil is driven alternately. The induction heating cooker according to claim 1, wherein the first heating coil is substantially circular, and the second heating coil is substantially elliptical. The induction heating cooker according to claim 1 or 2, wherein the plate-containing coil constants of the first and second heating coils are substantially the same. A temperature sensor for sensing the temperature of the plate is provided around each of the first and second heating coils, and the sensed temperature is low when the sensed temperature difference exceeds a certain value. The induction heating cooker according to any one of claims 1 to 3, wherein the electric power supply ratio to the heating coil is increased, and the sensed temperature difference is controlled to be a predetermined value or less. At the time of preheating the plate, only the first heating coil is driven, and after the temperature of the plate reaches the first predetermined temperature, the driving ratio of the second heating coil is set to be higher than that of the first heating coil. The induction heating cooker according to claim 4, wherein the induction heating cooker is controlled until the second predetermined temperature is reached while being increased by two times or more. The said 1st heating coil and said 2nd heating coil are controlled so that the temperature of the said plate center part may be about 200 degreeC, and the temperature of the left-right outer peripheral part of the said plate may be about 100 degreeC. Induction heating cooker.

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