JP2008027728A - Electromagnetic cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic cooker capable of uniformalizing temperature distribution at the bottom face of a heating object and suppressing a coil current flowing in each one heating coil even if the power is increased. <P>SOLUTION: The electromagnetic cooker is provided with a closed magnetic path forming means 13 which each of heating coils 4a-4c has, high frequency power generating circuits 2a-2c which drive individually each of the heating coils, and a control circuit 3 which controls output power of each high frequency power generating circuit. The control circuit 3 simultaneously drives each high frequency power generating circuit and fixes or changes its output power ratio to a prescribed value. Thereby, the whole bottom face of the heating object 5 is heated continuously and heating distribution of the bottom face of the heating object can be changed to enable uniformalization of the temperature distribution of the bottom face of the heating object 5. Furthermore, coil current of each heating coil is dispersed and the coil current per one heating coil can be suppressed. Furthermore, the closed magnetic path forming means 13 can suppress interference of the electromagnetic field generated by each heating coil and simultaneous drive of each heating coil becomes possible. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electromagnetic cooker used in general homes, offices, restaurants and the like.

  Conventionally, in this type of electromagnetic cooker, one heating coil formed in a spiral shape with respect to one object to be heated is provided, and the output power of a high frequency inverter that drives one heating coil is controlled and adjusted. There is an electromagnetic cooker that adjusts the temperature of an object to be heated (see, for example, Patent Document 1).

  Moreover, in the electromagnetic cooker which drives the several heating coil from which the heating coil is substantially concentric and arrange | positioned in the substantially same plane shape from which the diameter differs individually with several high frequency electric power circuits, one heating coil is driven In some cases, a technique is known in which the other heating coil is not driven and each high-frequency power is controlled and adjusted (see, for example, Patent Document 2).

FIG. 14 shows an electromagnetic cooker of Patent Document 2. However, it shows about the case where there are two heating coils. As shown in the figure, the electromagnetic cooker 20, the first high-frequency power generation circuit 15a, the second high-frequency power generation circuit 15b (two high-frequency power generation circuits 15 together), the control circuit 16, and the first A heating coil 17a, a second heating coil 17b (two heating coils 17 in total), a heated body 18, and a top plate 19 are included.
JP 2004-031247 A JP-A-8-78148

  However, in the conventional configuration described in Patent Document 1, the magnetic flux generated by the heating coil is maximized near the center in the radial direction of the heating coil, so that the bottom surface temperature of the object to be heated is near the center in the radial direction of the heating coil. There is a problem that heating becomes uneven due to a donut-shaped heating distribution that becomes higher and lower in other places.

  Moreover, in the structure of the above-mentioned conventional patent document 2, the heating coil is divided into a plurality of parts, and the divided heating coils are individually driven by a high-frequency and high-frequency power generation circuit to improve the donut-shaped heating distribution. However, since the second heating coil 17b is not driven when the first heating coil 17a is heated, the output power ratio of the first high-frequency power generation circuit 15a is as shown by a curve A7 in FIG. The output power ratio of the second high frequency power generation circuit 15b is set as shown by a curve B7 in FIG.

  The temperature distribution on the bottom surface of the heated object 18 in the period T8 shown in FIG. 15 is high near the center of the heated object 18 and low near the outer periphery as shown in FIG. Further, the temperature distribution on the bottom surface of the heated body 18 in the period T9 shown in FIG. 15 is high near the center of the heated body 18 and low near the outer periphery as shown in FIG. Since the electromagnetic cooker 20 shown in FIG. 14 periodically repeats FIGS. 16A and 16B, the temperature distribution on the bottom surface of the heated body 18 becomes a curve Tmp10 shown in FIG. The distribution is improved, but the temperature distribution is not uniform. In addition, the electromagnetic cooker 20 does not drive the other heating coil when one heating coil is being driven. Therefore, when the power is increased, the coil current that flows per one heating coil increases, resulting in a predetermined timing. The rated voltage or rated current of the switching element that generates high-frequency power by turning on and off at the time rises, and the cooling system is increased in size.

  Further, when the heating coil to be driven is switched while water is boiled through the heated object 18, a phenomenon that the boiled bubbles disappear for a moment occurs. There is also a problem of giving.

  The present invention solves the above-mentioned conventional problems, and not only makes the temperature distribution of the bottom surface of the object to be heated uniform, but also suppresses the coil current that flows per heating coil even when the power is increased, and boils. An object is to provide an electromagnetic cooker capable of continuously generating bubbles therein.

  In order to solve the above-described conventional problems, an electromagnetic cooker according to the present invention includes a plurality of heating coils arranged in substantially concentric and substantially coplanar shapes and having different diameters for heating a heated object, and the plurality of heating coils. Each of which includes a closed-time path forming means, a plurality of high-frequency power generation circuits that individually drive the plurality of heating coils, and a control circuit that controls output power of the plurality of high-frequency power generation circuits. The circuit simultaneously drives the plurality of high-frequency power generation circuits and fixes or changes the output power ratio of the plurality of high-frequency power generation circuits to a predetermined value.

  As a result, the entire bottom surface of the heated body is always heated, and the heating distribution on the bottom surface of the heated body can be changed, so that the temperature distribution on the bottom surface of the heated body can be made uniform. Become. In addition, since a plurality of heating coils are driven simultaneously, the coil current is dispersed to the plurality of heating coils even when the power is increased, and the coil current per heating coil can be suppressed. Can be continuously generated. Further, since each of the plurality of heating coils has the closed time path forming means, interference of electromagnetic fields generated from each of the plurality of heating coils can be suppressed, and the plurality of heating coils can be driven simultaneously.

  The electromagnetic cooker according to the present invention makes it possible to make the temperature distribution on the bottom surface of the object to be heated uniform, to suppress the coil current per heating coil even when the power is increased, and to continue the bubbles that are boiling. Can be generated.

  According to a first aspect of the present invention, there are provided a plurality of heating coils having substantially the same concentric shape and substantially in the same plane and having different diameters for heating an object to be heated, closed time path forming means included in each of the plurality of heating coils, A plurality of high-frequency power generation circuits that individually drive the heating coils, and a control circuit that controls output power of the plurality of high-frequency power generation circuits, wherein the control circuit simultaneously connects the plurality of high-frequency power generation circuits. By driving an electromagnetic cooker that drives and fixes or changes the output power ratio of the plurality of high-frequency power generation circuits to a predetermined value, the entire bottom surface of the heated object is constantly heated, and the heated object Therefore, the temperature distribution on the bottom surface of the object to be heated can be made uniform. In addition, since a plurality of heating coils are driven simultaneously, the coil current is dispersed to the plurality of heating coils even when the power is increased, and the coil current per heating coil can be suppressed. Can be continuously generated. Further, since each of the plurality of heating coils has the closed time path forming means, interference of electromagnetic fields generated from each of the plurality of heating coils can be suppressed, and the plurality of heating coils can be driven simultaneously.

  According to a second aspect of the invention, in particular, in the first aspect of the invention, the control circuit continuously changes the heating power distribution on the bottom surface of the object to be heated by continuously changing the output power ratio of the plurality of high frequency power generation circuits. Therefore, the temperature distribution on the bottom surface of the heated object can be made uniform.

  According to a third invention, in particular, in the first or second invention, the control circuit sets the output power ratio inversion period of the plurality of high-frequency power generation circuits to be higher than the audible frequency band. Since the heating distribution can be changed from the inside to the outside and vice versa, not only can the temperature distribution on the bottom surface of the heated body be made uniform, but also via the heated body. Convection is generated in the heated liquid cooking product, the temperature of the cooking product can be made uniform, and cooking performance can be improved.

  According to a fourth aspect of the invention, in particular, in any one of the first to third aspects of the invention, the temperature detection means for detecting the temperature of the bottom surface of the object to be heated is provided, and the control circuit corresponds to the detection result of the temperature detection means. By changing the output power ratio of a plurality of high-frequency power generation circuits, it becomes possible to change the heating distribution so as to concentrate and heat the bottom surface of the object to be heated. The temperature distribution on the bottom surface can be made uniform, and the cooking performance can be improved.

  According to a fifth aspect of the present invention, in particular, in any one of the first to fourth aspects of the present invention, the display device that indicates that the operation mode for changing the output power ratio is being provided. Since it becomes possible to grasp a heating state, it becomes possible to improve ease of use and cooking performance.

  In particular, the sixth invention includes a plurality of output power detection means for individually detecting the output powers of the plurality of high-frequency power generation circuits in any one of the first to fifth inventions, and the control circuit includes: Even if the plurality of high-frequency power generation circuits are driven in the absence of a heating body, a plurality of switching elements that are included in each of the plurality of high-frequency power generation circuits and that are turned on / off at a predetermined timing do not cause destruction. The heating circuit is driven at the start of heating, and the control circuit determines the presence or absence of the object to be heated according to the detection results of the plurality of output power detection means. This makes it possible to suppress a failure mode in which the heating target is not disposed above the plurality of heating coils and destroys the switching element, thereby improving the safety of the electromagnetic cooker. It becomes possible.

  In particular, according to a seventh invention, in any one of the first to sixth inventions, a plurality of output power detection means for individually detecting output powers of the plurality of high-frequency power generation circuits, and a bottom diameter of the object to be heated And a control circuit is included in each of the plurality of high-frequency power generation circuits even when the plurality of high-frequency power generation circuits are driven without a heated body, and has a predetermined timing. The plurality of heating coils are driven at the start of heating with power that does not cause destruction of the switching elements that are turned on and off at the bottom, and the bottom diameter determining means is configured to detect the bottom of the object to be heated based on the detection results of the plurality of output power detecting means. Judge the diameter. As a result, the control circuit can optimally select the output power ratio according to the determination result of the bottom diameter determination means, that is, according to the size of the bottom surface diameter of the heated object, and improve the cooking performance. Is possible.

  According to an eighth aspect of the invention, in particular, in the seventh aspect of the invention, the control circuit determines the output power ratio of the plurality of high frequency power generation circuits based on the determination result of the bottom diameter determination means at the start of heating. Unnecessary power that does not contribute can be suppressed, and efficiency can be improved.

  In particular, according to a ninth invention, in any one of the first to eighth inventions, a plurality of temperature detection means arranged at different positions, and the object to be heated based on the detection results of the plurality of temperature detection means. Cooking position detecting means for detecting the position of the food heated via the control circuit, and the control circuit changes the output power ratio of the plurality of high-frequency power generation circuits according to the detection result of the cooking position detection means. Thus, the bottom surface of the heated object in the vicinity of the cooked food can be concentrated and heated, and the cooking performance can be improved.

  In a tenth aspect of the invention, in particular, in any one of the first to ninth aspects, the control circuit sets the drive frequency of each of the plurality of high frequency power generation circuits to be higher than the audible frequency band and to the same frequency. In addition, it is possible to suppress the interference sound generated due to the driving frequency and the driving frequency difference of the plurality of heating coils, and it is possible to improve the ease of use.

  In an eleventh aspect of the invention, in particular, in any one of the first to ninth aspects, the control circuit has a driving frequency of each of the plurality of high-frequency power generation circuits higher than an audible frequency band, and the plurality of high-frequency power generation circuits By setting multiple different frequencies where the drive frequency difference is higher than the audible frequency band, it is possible to suppress the interference sound that occurs due to the drive frequency of multiple heating coils and the drive frequency difference, making it easy to use It is possible to improve the thickness.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a main configuration of an electromagnetic cooker according to an embodiment of the present invention. In addition, although the electromagnetic cooker shown in the figure is provided with only one burner (heating unit), there is no problem even with the electromagnetic cooker provided with a plurality of burners. Moreover, although the electromagnetic cooker shown in the figure includes three heating coils, there is no problem as long as there are at least two heating coils.

  As shown in the figure, the electromagnetic cooker 1 includes a switching element that is turned on and off at a predetermined timing, and generates a high-frequency power having a predetermined frequency from a 200 V commercial power source that is a low-frequency AC power source via a rectifier circuit. The high-frequency power generation circuit 2a, the second high-frequency power generation circuit 2b, and the third high-frequency power generation circuit 2c (three high-frequency power generation circuits 2 in total) control the output power of the three high-frequency power generation circuits 2 It has a control circuit 3 that is driven to move and that fixes or changes the output power ratio of the plurality of high-frequency power generation circuits 2 to a predetermined value. The electromagnetic cooker 1 also has a first heating coil 4a, a second heating coil 4b, and a third heating that are arranged in substantially concentric and substantially coplanar shapes that generate high-frequency magnetic flux by high-frequency power. A coil 4c (a total of three heating coils 4), a heated object 5 such as a pan, a frying pan, and the like, and three high-frequency power generation circuits 2 disposed substantially above the three heating coils 4 induction-heated by high-frequency magnetic flux. The first output power detection means 6a, the second output power detection means 6b and the third output power detection means 6c (three output power detection means 6 in total) for detecting the output power, respectively, the bottom surface of the heated object 5 First temperature detecting means 8a, second temperature detecting means 8b, and third temperature detecting means 8c for detecting the temperature via the hard glass top plate 7 (three temperature detecting means 8 in total) A bottom diameter determining means 9 for determining the bottom diameter of the body 5 to be heated based on the detection results of the three output power detecting means 6, a button for adjusting the temperature by the user, and an operation / display unit 10 for displaying the operation content. There is provided a cooking object position detecting means 11 for detecting the position of the food item heated via the heated object 5 based on the detection results of the three temperature detecting means 8, and a display means 12 for displaying on the operation / display unit 10. is doing.

  In the present embodiment, the inner diameter of the first heating coil 4a is φ50mm, the outer diameter is φ80mm, the inner diameter of the second heating coil 4b is φ90mm, the outer diameter is φ130mm, and the inner diameter of the third heating coil 4c is φ140mm, The outer shape is arranged as φ180 mm. These diameters can be arbitrarily set. In the present embodiment, the three heating coils 4 are circular. However, other shapes such as a rectangle, an ellipse, or a polygon may be used. Further, the three heating coils 4 can have different shapes. The first heating coil 4a is driven by the first high-frequency power generation circuit 2a, the second heating coil 4b is driven by the second high-frequency power generation circuit 2b, and the third heating coil 4c is the third high-frequency power generation circuit 2b. It is driven by the power generation circuit 2c.

  Further, in the present embodiment, each of the plurality of heating coils 4 includes the closed magnetic path forming means 13 in the vicinity.

  The operation and action of the electromagnetic cooker 1 configured as described above will be described below.

  The user operates the operation / display unit 10 with a pan, a frying pan, or the like to be heated 5 placed by the user so as to be substantially opposed to the three heating coils 4 via the hard glass top plate 7. When the temperature is set and the heating start button is pressed, the control circuit 3 drives the three high-frequency power generation circuits 2 in the absence of the object to be heated 5, and the three heating coils 4 with power that does not cause destruction of the switching elements. Drive.

  At this time, according to the detection results of the three output power detection means 6, the control circuit 3 determines the presence or absence of the heated body 5 substantially above the three heating coils 4. 2 is stopped, and the operation / display unit 10 displays that there is no object to be heated 5. When it is determined that the heated body 5 is present, the first output power detection means 6a for detecting the output power of the first high frequency power generation circuit 2a that drives the first heating coil 4a, and the second heating coil 4b. The second output power detection means 6b for detecting the output power of the second high frequency power generation circuit 2b for driving the second heating power 4c and the third output for detecting the output power of the third high frequency power generation circuit 2c for driving the third heating coil 4c. 3 compares the detection results of the output power detection means 6c. Then, if the detection result of the first output power detection means 6a is high, the output power ratios of the three high-frequency power generation circuits 2 based on the determination result of the bottom diameter determination means 9 that determines that the bottom diameter of the heated body 5 is small. Is optimally selected, and the three high-frequency power generation circuits 2 are driven.

  However, the bottom diameter determining means 9 performs determination after correcting the different inductance values of the three heating coils 4 for the detection results of the three output power detecting means 6.

  When the three heating coils 4 generate a high-frequency magnetic flux by high-frequency power and the high-frequency magnetic flux is magnetically coupled to the heated body 5, an induced eddy current is generated on the bottom surface of the heated body 5, and the heated body 5 is induction-heated. Is done. The control circuit 3 optimally selects the output power ratios of the three high-frequency power generation circuits 2 based on the detection results of the three temperature detection means 8 or the food item position detection means 11.

  Further, the control circuit 3 is operated by using the display means 12 to indicate that it is in an operation mode in which the output power ratio of the three high-frequency power generation circuits 2 is changed in order to make the temperature distribution on the bottom surface of the heated body 5 uniform. -It displays on the display part 10.

  As described above, the electromagnetic cooker 1 according to the present embodiment simultaneously drives the three heating coils 4 and fixes or changes the output power ratio of the three high-frequency power generation circuits 2 to a predetermined value, thereby heating the object. The temperature distribution on the bottom surface of the body 5 is made uniform. Further, since the three heating coils 4 are simultaneously driven, the heating coil current is distributed to three so that the power of the three heating coils 4 is 100% even when the power is increased. For this reason, not only the coil current flowing per heating coil can be suppressed, but there is no switching time lag of the heating coil to be driven even when water is boiled through the heated body 5. Therefore, it is possible to continuously generate boiling bubbles and improve cooking performance. At this time, since each of the plurality of heating coils 4 includes the closed magnetic path forming means 13, interference of electromagnetic fields generated from each of the plurality of heating coils 4 can be suppressed, so that the plurality of heating coils 4 can be driven simultaneously. It is.

  Further, as shown in FIG. 2, the control circuit 3 sets the output power ratio of the first high frequency power generation circuit 2a by continuously changing it as shown by a curve A1, and similarly generates the second high frequency power generation. The output power ratio of the circuit 2b is set as shown by the curve B1, the output power ratio of the third high frequency power generation circuit 2c is set as shown by the curve C1, and the output power of the three high frequency power generation circuits 2 is set to 100. % Is set to be%. The temperature distribution on the bottom surface of the heated body 5 at time t1 shown in FIG. 2 is high near the center of the heated body 5 and low near the outer periphery as shown in FIG. In addition, the temperature distribution on the bottom surface of the heated body 5 at time t2 shown in FIG. 2 is high near the center in the radial direction of the heated body 5 as shown in FIG. Further, the temperature distribution on the bottom surface of the heated body 5 at time t3 shown in FIG. 2 is high near the outer periphery of the heated body 5 and low near the center as shown in FIG. Since the electromagnetic cooker 1 in the present embodiment periodically repeats (a), (b), and (c) of FIG. 3, the temperature distribution on the bottom surface of the heated body 5 is a curve shown in FIG. 3 (d). It becomes Tmp1, and it becomes possible to make temperature distribution more uniform than curve Tmp10 of FIG.3 (d) which shows the temperature distribution of the electromagnetic cooker of patent document 2, and can improve cooking performance.

  As shown in FIG. 4, the control circuit 3 sets the output power ratio of the first high-frequency power generation circuit 2a as shown by a curve A2, and similarly, the output power ratio of the second high-frequency power generation circuit 2b. Is set as curve B2, the output power ratio of the third high-frequency power generation circuit 2c is set as curve C2, and the output power of the three high-frequency power generation circuits 2 is set to 100%. To do. The control circuit 3 sets the output power ratio inversion period of the plurality of high frequency power generation circuits 2 to be higher than the audible frequency band.

  When the liquid cooked product is heated via the heated body 5, convection occurs in the cooked product in the arrow direction shown in FIG. 5A during the period T1 shown in FIG. In the period T2 shown in FIG. 4, convection occurs in the cooked product in the direction of the arrow shown in FIG. In the period T3 shown in FIG. 4, convection occurs in the cooked product in the direction of the arrow shown in FIG. The electromagnetic cooker 1 in the present embodiment periodically repeats FIGS. 5A, 5B, and 5C, and the temperature distribution on the bottom surface of the heated body 5 becomes a curve Tmp2 shown in FIG. It is possible not only to make the temperature distribution more uniform than the curve Tmp10 of FIG. 5 (d), which shows the temperature distribution of the electromagnetic cooking device 1 referred to Patent Document 2, but also by generating convection in the cooked food. The temperature distribution of the object can be made uniform, and the cooking performance can be improved. That is, since the heating distribution on the bottom surface of the heated body 5 can be changed from the inside to the outside, and conversely from the outside to the inside, the heating distribution on the bottom surface of the heated body 5 can be made uniform. In addition to this, convection is generated in the liquid cooking product heated through the heated object 5, the temperature of the cooking product can be made uniform, and cooking performance can be improved.

  Further, as shown in FIG. 6, the control circuit 3 regards the adjacent first heating coil 4a and second heating coil 4b as one set of heating coils, and the output power of the first high-frequency power generation circuit 2a. The ratio is set as a curve A3, and similarly, the output power ratio of the second high frequency power generation circuit 2b is set as the curve B3 of FIG. 6, and the output power ratio of the third high frequency power generation circuit 2c is It is also possible to set the curve C3 so that the output power of the three high-frequency power generation circuits 2 is 100%. When the liquid cooked product is heated via the body 5 to be heated, convection occurs in the cooked product in the arrow direction shown in FIG. 7A during the period T4 shown in FIG. In the period T5 shown in FIG. 6, convection occurs in the cooked product in the arrow direction shown in FIG. The electromagnetic cooker 1 in the present embodiment periodically repeats FIGS. 7A and 7B, and the temperature distribution on the bottom surface of the heated body 5 becomes a curve Tmp3 shown in FIG. 7C, which shows the temperature distribution of the electromagnetic cooker 1 of FIG. 7C, the temperature distribution can be made more uniform than the curve Tmp10 of FIG. 7C. Can be made uniform, and cooking performance can be improved. Similarly, even if the adjacent second heating coil 4b and the third heating coil 4c are regarded as one set of heating coils, it is possible to arbitrarily combine the adjacent heating coils.

  Further, as shown in FIG. 8, the control circuit 3 performs the first operation based on the detection results of the three temperature detecting means 8 that detect the bottom surface temperature of the heated body 5 via the hard glass top plate 7. The output power ratio of the high frequency power generation circuit 2a is set as shown by a curve A4, the output power ratio of the second high frequency power generation circuit 2b is set as shown by a curve B4, and the output power of the third high frequency power generation circuit 2c is set. The ratio is set as indicated by a curve C4, and the output power of the three high-frequency power generation circuits 2 is set to 100% in total. In the period T6 shown in FIG. 8, when the temperature distribution on the bottom surface of the heated object 5 becomes nonuniform as shown by the curve Tmp4 in FIG. According to the detection result, the control circuit 3 detects the non-uniformity of the temperature distribution of the object 5 to be heated, and the output power ratio is set so that the power at the high temperature part is low and the power at the low temperature part is high. Is changed as shown in the period T7 in FIG. 8, the temperature distribution on the bottom surface of the heated body 5 can be stabilized in a uniform state as shown by the curve Tmp5 in FIG. 9, and cooking performance is improved. Can do.

  Further, as shown in FIGS. 10 and 11, when the bottom diameter of the heated body 5 is small, the control circuit 3 sets the first heating coil 4 a based on the determination result of the bottom diameter determination means 9 at the start of heating. The output power ratio of the first high-frequency power generation circuit 2a to be driven is set high as shown by a curve A5 in FIG. 10, and the output power ratio of the second high-frequency power generation circuit 2b to drive the second heating coil 4b is curved. The output power ratio of the third high-frequency power generation circuit 2c that drives the third heating coil 4c disposed outside is set as low as B5, and is set as low as the curve C5. The total output power of the three high-frequency power generation circuits 2 is set to 100%. The temperature distribution on the bottom surface of the object 5 to be heated is a curve Tmp6 shown in FIG. 11, and the temperature distribution can be made more uniform than the curve Tmp7 in FIG. In addition, it is possible to suppress the coil current flowing through the third heating coil 4c arranged outside that does not contribute much to heating, and the heating efficiency and cooking performance can be improved.

  Furthermore, as shown in FIGS. 12 and 13, when the food 14 to be heated via the heated body 5 is concentrated near the center of the heated body 5, the control circuit 3 determines the first temperature detection result. 8a, based on the detection results of the second temperature detection result 8b and the third temperature detection result 8c, that is, the detection result of the food position detection means 11, the detected temperature of the first temperature detection means 8a is the second temperature. If it is detected that the temperature rise is smaller than the detected temperatures of the detection means 8b and the third temperature detection result 8c, it is determined that the food 14 is located near the center of the heated body 5. Then, the output power ratio of the first high-frequency power generation circuit 2a that drives the first heating coil 4a disposed inside is set high as shown by a curve A6 in FIG. 12, and the second heating coil 4b is driven. The output power ratio of the second high frequency power generation circuit 2b is set low as shown by the curve B6 in FIG. 12, and the output power ratio of the third high frequency power generation circuit 2c that drives the third heating coil 4c is set as shown in FIG. The curve C6 is set as low as the curve C6, and the output power of the three high-frequency power generation circuits 2 is set to 100%. The temperature distribution on the bottom surface of the heated object 5 is a curve Tmp8 shown in FIG. 13, and the heated object 5 near the cooked product 14 is more concentrated than the curve Tmp9 of FIG. Thus, heating is possible, and cooking performance can be improved.

  Conversely, when it is detected that the detected temperature of the second temperature detecting means 8b and the third temperature detecting means 8c is larger than the detected temperature of the first temperature detecting means 8a, the food 14 Is set near the outer periphery of the body 5 to be heated, the output power ratio of the first high-frequency power generation circuit 2a that drives the first heating coil 4a disposed inside is set low, and The output power ratio of the second high frequency power generation circuit 2b that drives the arranged second heating coil 4b and the output power ratio of the third high frequency power generation circuit 2c that drives the third heating coil 4c are set high. . The total output power of the three high-frequency power generation circuits 2 is set to 100%.

  In addition, the control circuit 3 sets the driving frequency of each of the three high-frequency power generation circuits 2 to about 20 kHz or higher, which is higher than the audible frequency band, and the same frequency. Interference sound generated due to this can be suppressed, and a comfortable use environment can be provided to the user.

  The control circuit 3 has a driving frequency of the three high-frequency power generation circuits 2 of about 20 kHz or higher, which is higher than the audible frequency band, and a driving frequency difference between the three high-frequency power generation circuits 2 is about 20 kHz or higher, which is higher than the audible frequency band. By using the three different frequencies, it is possible to suppress the interference sound generated due to the driving frequency and the driving frequency difference of the three heating coils 4, and provide a comfortable use environment for the user.

  In the present embodiment, three heating coils are used, but it goes without saying that the temperature distribution can be made more uniform as the number of heating coils increases.

  As described above, the electromagnetic cooker according to the present invention can make the temperature distribution on the bottom surface of the object to be heated uniform, can suppress the coil current per heating coil even when the power is increased, and boils. Since it is possible to continuously generate bubbles, it can be applied not only to ordinary homes and offices but also to professionals such as restaurants.

The block diagram of the electromagnetic cooker in Embodiment 1 of this invention Output power state diagram with continuously changing output power ratio in the same electromagnetic cooker (A) Heat distribution diagram at time t1 when the output power ratio is continuously changed in the electromagnetic cooker (b) Heat distribution diagram at time t2 (c) Convection state diagram at time t3 (d) Temperature distribution at stable temperature Figure Output power state diagram with inverted output power ratio in the same electromagnetic cooker (A) Convection state diagram in period T1 when the output power ratio is inverted in the electromagnetic cooker (b) Convection state diagram in period T2 (c) Convection state diagram in period T3 (d) Temperature distribution diagram when temperature is stable Output power state diagram with inverted output power ratio in the same electromagnetic cooker (A) Convection state diagram in period T4 when the output power ratio is inverted in the electromagnetic cooker (b) Convection state diagram in period T5 (c) Temperature distribution diagram at stable temperature Output power state diagram with changing output power ratio by temperature control in the same electromagnetic cooker Temperature distribution diagram when the output power ratio is changed by temperature control in the same electromagnetic cooker Output power state diagram in which the output power ratio is changed when the bottom surface of the heated object is small in the electromagnetic cooker Temperature distribution diagram when the output power ratio is changed when the bottom surface of the heated object is small in the electromagnetic cooker Output power state diagram in which the output power ratio is changed by the food position detection means in the same electromagnetic cooker Temperature distribution diagram when the output power ratio is changed by the food position detection means in the same electromagnetic cooker Configuration of conventional electromagnetic cooker Output power state diagram of the conventional electromagnetic cooker (A) Heat distribution diagram during period T8 of the conventional electromagnetic cooker (b) Heat distribution diagram during period T9 (c) Temperature distribution diagram when temperature is stable

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electromagnetic cooker 2 Three high frequency electric power generation circuits 2a 1st high frequency electric power generation circuit 2b 2nd high frequency electric power generation circuit 2c 3rd high frequency electric power generation circuit 3 Control circuit 4 Three heating coils 4a 1st heating coil 4b Second heating coil 4c Third heating coil 5 Heated body 6 Three output power detection means 6a First output power detection means 6b Second output power detection means 6c Third output power detection means 8 Three temperatures Detection means 8a 1st temperature detection means 8b 2nd temperature detection means 8c 3rd temperature detection means 9 Bottom diameter judgment means 11 Cooking object position detection means 12 Display means 13 Closed magnetic circuit formation means

Claims (11)

A plurality of heating coils having substantially the same concentric shape and arranged in substantially the same plane and having different diameters for heating an object to be heated, closed-circuit forming means included in each of the plurality of heating coils, and each of the plurality of heating coils A plurality of high-frequency power generation circuits, and a control circuit for controlling output power of the plurality of high-frequency power generation circuits, wherein the control circuit simultaneously drives the plurality of high-frequency power generation circuits, and An electromagnetic cooker that fixes or changes the output power ratio of the high-frequency power generation circuit of the above to a predetermined value. The electromagnetic cooker according to claim 1, wherein the control circuit continuously changes the output power ratio of the plurality of high-frequency power generation circuits. The electromagnetic cooker according to claim 1 or 2, wherein the control circuit sets the output power ratio inversion period of the plurality of high-frequency power generation circuits to be higher than the audible frequency band. The temperature detection means which detects the temperature of the bottom face of a to-be-heated body is provided, and a control circuit changes the output power ratio of several high frequency electric power generation circuits according to the detection result of the said temperature detection means. The electromagnetic cooker according to item 1. The electromagnetic cooker of any one of Claims 1-4 provided with the display means which shows that it is in the operation mode which changes output power ratio. A plurality of output power detection means for individually detecting the output power of the plurality of high-frequency power generation circuits, and the control circuit drives the plurality of high-frequency power generation circuits in the absence of an object to be heated; A plurality of heating coils are driven at the start of heating with power that does not cause destruction of switching elements that are included in each of the high-frequency power generation circuits and that are turned on / off at a predetermined timing, and the control circuit includes the plurality of output power detection means The electromagnetic cooker of any one of Claims 1-5 which judges the presence or absence of the said to-be-heated body according to the detection result. The control circuit includes a plurality of output power detection means for individually detecting the output power of the plurality of high-frequency power generation circuits and a bottom diameter determination means for determining the bottom diameter of the heated object, and the control circuit is in a state where there is no heated object. Even when the plurality of high-frequency power generation circuits are driven, the plurality of high-frequency power generation circuits are included in each of the plurality of high-frequency power generation circuits, and the switching elements that are turned on / off at predetermined timings heat the plurality of heating coils with power that does not cause destruction The electromagnetic cooker according to any one of claims 1 to 6, which is driven at the start, and wherein the bottom diameter determining means determines the bottom diameter of the object to be heated based on detection results of the plurality of output power detection means. The electromagnetic cooker according to claim 7, wherein the control circuit determines an output power ratio of the plurality of high-frequency power generation circuits based on a determination result of the bottom diameter determination means at the start of heating. A plurality of temperature detection means arranged at different positions, and a food position detection means for detecting the position of the food to be heated via the object to be heated based on the detection results of the plurality of temperature detection means; The electromagnetic cooker according to any one of claims 1 to 8, wherein the circuit changes an output power ratio of the plurality of high-frequency power generation circuits in accordance with a detection result of the food position detection means. The electromagnetic cooker according to any one of claims 1 to 9, wherein the control circuit sets the drive frequency of each of the plurality of high-frequency power generation circuits to be higher than an audible frequency band and to the same frequency. The control circuit sets the driving frequency of each of the plurality of high-frequency power generation circuits to a plurality of different frequencies that are higher than the audible frequency band and the driving frequency difference of each of the plurality of high-frequency power generation circuits is higher than the audible frequency band. The electromagnetic cooker of any one of Claims 1-9.