JP2007305490A - Manufacturing method of heating coil, and heating coil of electromagnetic induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a heating coil capable of heating an object uniformly, and making a circuit configuration of a driving circuit simple. <P>SOLUTION: A method of manufacturing a heating coil comprises the first process S2 in which such conditions as an inside radius, an outside radius, and the like of a coil are set; the second process S5 in which the first split position 8 and the second split position 9 are set so that a current by which a container to be heated can reach a predetermined maximum heating temperature can be kept in a range of an allowable maximum current, and temperature distribution can satisfy predetermined uniformity; and the third process S10 in which the third split position is set so that both inductances of the sixth coil, and the seventh coil 14 will be nearly equal to each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a heating coil used in an electromagnetic induction heating cooker, and a heating coil manufactured by the manufacturing method.

  In a conventional electromagnetic induction heating cooker, the heating coil is divided and arranged, for example, as the outermost part, the middle part, the center part, etc., so that the heated container can be heated uniformly (for example, Patent Document 1).

  Furthermore, when the heating coil is divided into an inner coil and an outer coil, the inductance of the inner coil and the outer coil is made substantially the same to simplify the circuit configuration of the drive circuit (for example, Patent Document 2).

Japanese Utility Model Publication No. 6-70193 (5th page, Fig. 1) Japanese Patent Laid-Open No. 10-113278 (page 3, FIG. 2)

  However, in an electromagnetic induction heating cooker having a conventional heating coil divided into a plurality as described above, either the heated container can be heated uniformly or the inductance of each coil is substantially the same. On the other hand, there is no indication as to how to produce a heating coil that can uniformly heat the container to be heated and the inductance of each of the divided coils is substantially the same, As a result, it was not possible to realize a heating coil in which uniform heating was possible and each coil had substantially the same inductance.

  The present invention has been made in order to solve the above-described problems, and is a heating coil that can perform uniform heating and can simplify the circuit configuration of the drive circuit because the inductance of each of the divided coils is substantially the same. It aims at providing the manufacturing method of.

  In the heating coil manufacturing method according to the present invention, in the first step, the inner and outer radii of the first coil, the pitch at which the conductors of the first coil are spirally arranged at equal intervals, and the conductors are energized. In the second step, the first conductive wire, the first coil at the first division position and the second division position, which are different from each other in order from the inner circumference side to the outer circumference side in the second step, The fourth conductor is divided into two conductor wires and a third conductor wire, the second conductor wire is removed, and a second coil composed of the first conductor wire and a third coil composed of the third conductor wire are connected. When the coil is energized to heat the heated container, the temperature of the heated container is brought to a predetermined maximum heating temperature with the maximum current, and at the same time, the temperature distribution of the heated container is set to a predetermined uniformity. The first division position and the second division position so as to achieve In the third step, the third coil is divided into a fourth conductor and a fifth conductor at a third division position in order from the inner periphery to the outer periphery, and the second coil And the sixth coil formed by connecting the fifth coil made of the fourth conducting wire and the seventh coil made of the fifth conducting wire have substantially the same inductance, so that the third division is performed. The position was set.

  According to the present invention, the coil in which the conducting wires are arranged in a spiral shape at equal intervals is divided by providing a gap by removing a part of the conducting wire so that the temperature distribution of the heated container reaches a predetermined uniformity. When the divided outer peripheral coil is subdivided, the impedance of the coil in which the inner peripheral coil and the inner coil obtained by subdividing the outer peripheral coil are connected in series and the outer peripheral coil are re-divided. Since the re-dividing position is set so that the impedance of the outer coil obtained by the division is substantially the same, and the heating coil composed of two coils having the same impedance is configured, the container to be heated is The heating circuit can be uniformly heated, and at the same time, the driving circuit for driving the two coils can be simplified.

  Hereinafter, the manufacturing method of the heating coil according to the embodiment of the present invention, the temperature at the bottom of the pan when heated by assuming a stainless steel pot as a heated container in an electromagnetic induction heating cooker provided with the heating coil designed by this manufacturing method This will be explained based on the calculation result of.

  By the way, among the calculations described below, AC magnetic field analysis, pan bottom eddy current distribution analysis, pan bottom heat density distribution analysis due to Joule heat based on eddy current loss, and coil inductance analysis are all general purpose electromagnetic fields. EM Solution (registered trademark) manufactured by Science Solutions Co., Ltd., which is analysis software, was used. This general-purpose electromagnetic field analysis software can execute an electromagnetic field calculation by applying a three-dimensional finite element method to the Maxwell equation ignoring the displacement current.

  It should be noted that these calculations are not limited to this software, and it goes without saying that other commercially available software capable of electromagnetic field analysis can be used as long as it is compatible with the calculations described below. Yes.

  The electromagnetic induction heating cooker manufactures a heating coil that can be heated to a predetermined maximum heating temperature, such as a pot to be heated, and the pot bottom temperature distribution has a predetermined uniformity. Shall.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view of an example of a configuration for heating a stainless steel pan, viewed from the front side, in an electromagnetic induction heating cooker including the heating coil of Embodiment 1 designed by the method for manufacturing a heating coil according to the present invention. It is. For the sake of clarity, members such as ferrite cores that are not necessary for the description are omitted.

  The heating coil of the electromagnetic induction heating cooker has a spiral shape, and includes an inner peripheral coil 1 on the center side of the spiral and an outer peripheral coil 2 on the outer side. By connecting a drive circuit (not shown) to this heating coil and applying high frequency power, an AC magnetic field is generated, and a stainless steel pan 3 as an example of a container to be heated is uniformly heated. .

In the following description, the stainless steel material of the pan 3 is SUS430, the pan bottom diameter is 200 mm, and the pan bottom thickness is 2.5 mm. Further, assuming that the electromagnetic properties of SUS430 are a specific resistance of 5.0 × 10 ⁻⁷ Ωm and a relative permeability of 400, and thermal properties of 16 W / mK and a specific heat of 500 J / kg · K, an electromagnetic field is assumed. The heat conduction analysis using the analysis and the heat insulation model is carried out, but the material of the pan and the values of these constants are examples, and even if the pan is made of other materials, the material is Needless to say, may have different constants.

  Here, the frequency of the high-frequency power applied to the heating coil is 20 kHz, but it is needless to say that the frequency is not limited to this value.

  FIG. 2 is a plan view of the heating coil viewed from the upper surface side in order to explain the configuration of the heating coil shown in FIG. 1 in detail. The same reference numerals as those in FIG. 1 denote the same or corresponding parts, and thus description thereof is omitted.

  As apparent from FIG. 2, the inner peripheral coil 1 is composed of a coil part 1a on the center side of the spiral, and an outer coil part 1b arranged with a gap from the coil part 1a. The coil part 1a and the coil part 1b are connected in series. On the other hand, the outer peripheral coil 2 is provided close to the outside of the coil portion 1b.

  Connection terminals 4a and 4b are provided at both ends of the inner peripheral coil 1, and connection terminals 5a and 5b are provided at both ends of the outer peripheral coil 2, and these connection terminals 4a, 4b, 5a and 5b are used. The high frequency output of the drive circuit is energized.

  Usually, when the pan 3 as a heated container is large, both the inner coil 1 and the outer coil 2 are energized, and when the pan 3 is small, only the inner coil 1 is energized for use.

  Next, the design process of the heating coil of Embodiment 1 by the heating coil manufacturing method concerning this invention is demonstrated.

  FIG. 3 is a process flow diagram for explaining a design procedure for manufacturing a heating coil, and includes a first process for setting the outer dimensions of the heating coil to be manufactured and conditions for maximum energization, A second step for allowing the temperature distribution of the bottom of the pan to have a predetermined degree of uniformity, while at the same time the temperature of the bottom of the pan as a container can reach at least a predetermined maximum heating temperature with a maximum current; A third step of setting the third division position so that the inductance of the inner peripheral coil 1 composed of the coil portion 1a and the coil portion 1b shown in FIG. It is composed of

  4 is a plan view of the first coil viewed from the upper surface side for explaining the first step in the manufacturing process of the heating coil, and FIG. 5 is from the upper surface side for explaining the second step. FIG. 6 is a plan view of the fourth coil viewed from the upper surface side for explaining the third step, and FIG. 7 is the first step, the second step, and FIG. It is a top view of the heating coil obtained by designing with the process flow shown in FIG. 3 through the 3rd process.

  3, 4, 5, 6, and 7, the same reference numerals indicate the same or corresponding parts, and thus the description of those that have been described once will be omitted. Furthermore, the same reference numerals as those in FIGS. 1 and 2 indicate the same or corresponding parts, and thus the description thereof is omitted.

  Hereinafter, the manufacturing method of the heating coil according to the first embodiment will be described in detail with reference to FIGS.

  In FIG. 3, when starting the process start S1 which designs a heating coil in order to manufacture the heating coil of an electromagnetic induction heating cooking device, first, as a 1st process, the inner periphery radius R1 regarding the external dimension of the heating coil to manufacture. And condition setting S2 for setting the outer peripheral radius R2 based on the size of the pan to be heated.

  Here, the inner radius R1 is the distance between the center 6 of the heating coil shown in FIG. 4 and the connection terminal 4a, and the outer radius R2 is the distance between the center 6 of the heating coil shown in FIG. 4 and the connection terminal 5b. Distance.

  In the condition setting S2, after selecting the type and size of the conducting wire to be used, the pitch for arranging the conducting wires at equal intervals between the inner peripheral radius R1 and the outer peripheral radius R2 is set.

  Furthermore, the maximum current allowable by the drive circuit mounted on the electromagnetic induction heating cooker is set. In the following description, the high frequency current applied to the heating coil is adjusted so that the heat input to the pan bottom of the pan 3 is always 400 W as an example. In addition, the maximum heating temperature was set to 120 ° C. as a temperature suitable for grilled foods.

  Next, as a second step shown in FIG. 3, the connection terminal 4 a shown in FIG. 4 is spirally moved from the connection terminal 4 a to the circumferential side so that the temperature distribution of the pan bottom can be obtained by induction heating by a heating coil. Division provisional setting S3 is performed to provisionally divide the first coil 7 that spreads and terminates at the connection terminal 5b.

  Specifically, first, as shown in FIG. 4, a first division position 8 and a second division position 9 that are different from each other in order from the inner circumference side to the outer circumference side for dividing the first coil 7 are temporarily set. Then, the conducting wire of the first coil 7 is cut at these dividing positions, the first conducting wire 7a starting from the connection terminal 4a and ending at the first dividing position 8, and the first dividing position 8 as the starting end. A second conductor 7b that terminates at the second division position 9 and a third conductor 7c that terminates at the second division position 9 and ends at the connection terminal 5b are provided.

  Next, as shown in FIG. 5, the second conductive wire 7b is removed, and the second coil 10 made of the first conductive wire 7a and the third coil 11 made of the third conductive wire 7c are connected to form a fourth A coil.

  For the fourth coil shown in FIG. 5, general-purpose electromagnetic field software that has already explained the electromagnetic field analysis portion in the calculation S4 of the pot bottom temperature distribution by the electromagnetic field analysis and heat conduction analysis shown in FIG. First, an AC magnetic field distribution generated by a high-frequency current flowing through the fourth coil is obtained.

  Next, based on this AC magnetic field distribution, the eddy current distribution induced in the pan 3 is determined using the already-described general-purpose electromagnetic field software, and the eddy current generated according to the specific resistance value of the pan 3 is obtained. The loss is calculated and a pan bottom heat generation density distribution due to Joule heat of the pan 3 is obtained.

  Next, based on the obtained pan bottom heat generation density distribution, using a transient heat conduction analysis software created so as to apply a thermal network to the heat conduction equation and calculate by the difference method, in the division temporary setting S3 The pan bottom temperature distribution when the pan 3 is heated by the fourth coil obtained by dividing the first split position 8 and the second split position 9 is obtained.

  The unsteady heat conduction analysis software used here for the calculation of the pan bottom temperature distribution is self-made, but is not limited to this software, and the unsteady heat based on the pan bottom heat density distribution as the heat source. It goes without saying that any commercially available general-purpose heat conduction analysis software that can calculate conduction can be used for this calculation.

  Next, the current value at which the temperature of the pan bottom of the pan 3 can reach the predetermined maximum heating temperature is within the range of the allowable maximum current set in the condition setting S2, and the calculated pan bottom temperature distribution has a predetermined uniformity. In step 1S5, if the predetermined uniformity is reached, the process proceeds to the third step. If not, the process returns to the provisional temporary setting S3 of the first coil 7, and the first step The division position 8 and the second division position 9 are reviewed and temporarily set again. Thereafter, the same processing as described above is performed, and these processing is repeated until the pan bottom temperature distribution reaches a predetermined uniformity in the determination 1S5.

  When the second step is completed in S6, the third step is to divide the third coil 11 so that the inductances of the inner and outer peripheral coils 1 and 2 constituting the heating coil are substantially the same in the third step. Setting S7 is performed.

  Specifically, first, as shown in FIG. 6, a third division position 12 for dividing the third coil 11 is temporarily set, and the lead wire of the third coil 11 is cut at the third division position 12. Then, in order from the inner peripheral side toward the outer peripheral side, the fourth conductive wire 11a on the inner peripheral side with respect to the third divided position 12 and the fifth terminal end with the third divided position 12 as the start end and the connection terminal 5b as the end point. Lead wire 11b.

  Next, as shown in FIG. 7, the 5th coil 13 which consists of the 2nd coil 10 and the 4th conducting wire 11a is connected, and it is set as the 6th coil.

  Next, the inductance S8 of each of the seventh coil 14 including the sixth coil and the fifth conductor 11b is calculated from the magnetic flux interlinked with the coil by using the already-described general-purpose electromagnetic field software. In step 2S9, it is determined whether or not the values of the respective inductances are substantially the same. If the values are substantially the same, it is determined that the setting S10 of the third division position 12 has been completed, and the process flow ends in the process stop S11. However, if they are not substantially the same, the process returns to the provisional provisional setting S7 of the third coil 11, the third division position 12 is reviewed, and provisional setting is performed again. Thus, the process is repeated until each inductance value becomes substantially the same in the determination 2S9. Thus, the third division position 12 is set in S10, and the process ends in S11.

  The sixth coil obtained by the above process flow is the inner peripheral coil 1 itself composed of the coil portion 1a and the coil portion 1b shown in FIG. 2, and the seventh coil 14 is the outer peripheral coil 2 itself. Thus, the heating coil of the first embodiment designed by the heating coil manufacturing method of the first embodiment according to the present invention can be obtained.

  In addition, based on the process flow of the manufacturing method of the heating coil shown in FIG. 3, the example which performed the design is demonstrated still in detail below. Here, as an example, as a first step, the inner peripheral radius R1 of the heating coil is 13.8 mm, the outer peripheral radius R2 is 92.0 mm, and the pitch for arranging the conductors is 1.7 mm. In addition, an allowable maximum current energized from the driving circuit to be used was set.

  Furthermore, as already stated, the high frequency current applied to the heating coil is adjusted so that the heat input to the pan bottom of the pan 3 is always 400 W, and the predetermined maximum heating temperature is set to 120 ° C., for example.

  In addition, the uniformity of the pot bottom temperature in the radial direction of the heating coil means the ratio of the length of the pot bottom that falls within 10 ° C. from the predetermined maximum heating temperature to the low temperature side in the radius of the pot bottom. The uniformity is, for example, 50% or more.

  FIG. 8 is a pan bottom temperature distribution diagram in the pan radial direction of the pan 3 obtained by changing the combination of the first split position 8 and the second split position 9 in the second step shown in FIG. 3. The pan bottom temperature distribution curve 15 when the gap between the first division position 8 and the second division position 9 is 0 mm, the pan bottom temperature distribution curve 16 when the gap is 13.6 mm, and the gap is 28. A pan bottom temperature distribution curve 17 in the case of 9 mm and a pan bottom temperature distribution curve 18 in the case where the gap is 42.5 mm are shown.

  In FIG. 8, when the gap between the first division position 8 and the second division position 9 is increased, the length of the pan bottom that falls within 10 ° C. from the predetermined maximum heating temperature of 120 ° C. to the low temperature side becomes longer. It can be seen that the uniformity of the pan bottom temperature distribution tends to improve as the gap increases. In addition, in the case of the pan bottom temperature distribution curve 18 in the case where the gap is 42.5 mm, the degree of uniformity may be sufficient, but the ratio to be removed from the first coil as the second conducting wire 7b shown in FIG. 4 is extremely large. As a result, the portion that functions as a coil for induction heating becomes smaller, and the maximum heating temperature of the pan bottom cannot be reached at 120 ° C. with a predetermined maximum current. Therefore, the process flow shown in FIG. The determination was NO in the described determination 1S5.

  By the way, in the pan bottom temperature distribution curve 15 in the case where the gap is 0 mm, the uniformity is not significantly satisfied with 35% and the predetermined uniformity of 50%. In addition, in the pan bottom temperature distribution curve 16 when the gap is 13.6 mm, the uniformity is a little 46% but does not satisfy 50%. In such a case, especially when the gap is 13.6 mm, when water is poured into the pan 3 and boiled, bubbles are generated in a donut shape. In addition, when baking is performed, a donut-shaped burn may be formed.

  On the other hand, in the pan bottom temperature distribution curve 17 in the case of 28.9 mm, the pan bottom length within 10 ° C. is 64 mm, the uniformity is 64%, and the predetermined uniformity is 50%. The high-frequency current for causing the maximum heating temperature of the pan bottom to reach 120 ° C. did not exceed the predetermined maximum current.

  Thus, in the second step shown in FIG. 3, the position of 35.9 mm in the radial direction from the center 6 of the first coil 7 shown in FIG. Since the position of 64.8 mm is the second divided position 9 and the gap of 28.9 mm is made open, the current value that can reach the maximum heating temperature is within the allowable maximum current range, and the temperature of the pan bottom The distribution exceeded a predetermined uniformity of 50%, and the setting of the first division position 8 and the second division position 9 was completed, and the process could move to the third step.

  In the third step, the third division position 12 of the third coil 11 shown in FIG. 6 is set so that the inductances of the sixth coil and the seventh coil 14 are substantially the same. 9, the relationship between the number of turns of the heating coil and the inductance will be described.

  FIG. 9 is an inductance characteristic diagram showing the relationship of the magnitude of inductance per turn with respect to the outer diameter of the heating coil, assuming a one-turn heating coil.

  According to FIG. 9, it can be seen that the inductance per turn is substantially proportional to the outer diameter of the heating coil. Therefore, by dividing the third coil 11 at an appropriate position, the inductance value of the sixth coil and the inductance value of the seventh coil 14 are substantially the same without changing the uniformity of the pan bottom temperature distribution. It is possible to

  Therefore, as already described, in the manufacturing method shown in the third step of the process flow of FIG. 3, the third coil 11 has the third coil 11 so that the inductances of the sixth coil and the seventh coil 14 are substantially the same. 3 was obtained by electromagnetic field analysis, the third division position 12 shown in FIG. 6 was found to be a position of 75.0 mm in the radial direction from the center 6.

  As described above, the heating coil shown in FIG. 7 can be obtained by completing the third step shown in FIG. 3, and as already explained, the sixth coil is the coil part 1a and the coil part 1b shown in FIG. 2 and the seventh coil 14 is the outer peripheral coil 2 itself of FIG. 2, and an example of the heating coil of the first embodiment according to the present invention could be obtained.

  The dimensional shape of an example of the heating coil thus obtained will be described with reference to FIG. 2. The heating coil has an inner peripheral radius R1 of 13.8 mm and an outer peripheral radius R2 of 92.0 mm. Is 1.7 mm, the number of turns of the coil portion 1a constituting the inner peripheral coil 1 is 13 turns, the number of turns of the coil portion 1b is 6, and the outer periphery of the coil portion 1a and the inner periphery of the coil portion 1b A gap of 28.9 mm is provided between them. Further, the number of turns of the outer peripheral coil 2 is 10 turns.

  In the above description, the number of turns is determined with a pitch of 1.7 mm. However, even if the pitch is changed, the pot bottom temperature distribution and the point that the inner coil 1 and the outer coil 2 have substantially the same inductance are not affected. If the number of turns of the second coil 10 that is itself is A, the number of turns of the fifth coil 13 that is the coil portion 1b itself is B, and the number of turns of the seventh coil 14 that is the outer coil 2 itself is C. Needless to say, the relationship A: B: C = 13: 6: 10 is established.

  An electromagnetic induction heating cooker equipped with a heating coil having a drive circuit connected to each of the inner coil 1 as the sixth coil and the outer coil 2 as the seventh coil 14 obtained as described above is as follows. The pot bottom of the pot 3 as the heated container can be heated with a predetermined uniformity, and at the same time the impedances of the inner coil 1 and the outer coil 2 are substantially the same, so the respective drive circuits are the same. There is an effect that the drive circuit can be simplified.

  In addition, although it is impossible to use only the inner peripheral coil 1 in response to the small pan, the inner peripheral coil 1 as the sixth coil and the outer peripheral coil 2 as the seventh coil 14 are connected to one drive circuit. Can be connected in parallel and mounted on an electromagnetic induction heating cooker. When coils having different impedances are connected in parallel, the current flowing through the coils varies, and the waveform of the drive current changes, resulting in a problem that the drive efficiency of the heating coil decreases. Since the inner coil 1 and the outer coil 2 as the seventh coil 14 have substantially the same inductance, the drive efficiency is not lowered, and as a result, the container to be heated is made uniform. At the same time, the heating coil can be driven efficiently simply by connecting one drive circuit, and the drive circuit can be simplified.

Embodiment 2. FIG.
In the heating coil according to the manufacturing method of the first embodiment, the outer peripheral side of the inner peripheral coil that is the sixth coil is arranged close to the inner peripheral side of the outer peripheral coil that is the seventh coil. When a small pan is heated as a container, only the inner coil is driven without driving the outer coil. In that case, if the outer peripheral side of the inner peripheral coil and the inner peripheral side of the outer peripheral coil are approached without leaving a gap, the drive circuit will apply the inner peripheral coil to the inner peripheral coil due to the magnetic coupling between the inner peripheral coil and the outer peripheral coil. A part of the high frequency power is transmitted to the outer coil, and the magnetic flux leaks from the outer coil to the outside of the heating coil. As a result, there is a problem that the heating efficiency for the small pan is reduced.

  For this problem, it is effective to provide a gap between the outer peripheral side of the inner peripheral coil and the inner peripheral side of the outer peripheral coil.

  Specifically, in the process flow shown in FIG. 3 described in the first embodiment, the first process and the second process are the same as those in the first embodiment, and the third division position is set in the third process. After the setting, the connection between the second coil 10 and the fifth coil 13 shown in FIGS. 6 and 7 is released, and the predetermined number of turns in the fourth conductive wire 11a on the outer peripheral side of the fifth coil 13 is released. At the same time, the second coil 10 and the fifth coil 13 are connected again by adding the predetermined number of turns in the fourth conductor 11a on the inner periphery side to connect the sixth coil The coil was made. Note that matters other than those described above are the same as those described in the first embodiment.

  As a result, a gap corresponding to a predetermined number of turns is formed between the outer peripheral side of the sixth coil and the inner peripheral side of the seventh coil 14.

  FIG. 10 is a pan bottom temperature distribution diagram in the pan radial direction of the pan 3 when the width of the gap between the outer peripheral side of the sixth coil and the inner peripheral side of the seventh coil 14 is changed by the procedure described above. . A pot bottom temperature distribution curve 19 when there is no gap, a pot bottom temperature distribution curve 20 when a gap for three turns is formed, and a pot bottom temperature distribution curve 21 when a gap for seven turns is formed are shown.

  In FIG. 10, it can be seen that when the gap between the outer peripheral side of the sixth coil and the inner peripheral side of the seventh coil 14 is increased, the uniformity of the pan bottom temperature distribution tends to decrease.

  Furthermore, FIG. 11 is a pan-bottom heat generation density distribution diagram corresponding to FIG. 10, and shows a pan-bottom heat generation density distribution curve 22 when there is no gap and a pan-bottom heat density distribution when a gap of three turns is formed. A curve 23 and a pan-bottom heat generation density distribution curve 24 when a gap of 7 turns is formed are shown.

  According to FIG. 11, as shown in FIG. 10, the cause that the uniformity of the pot bottom temperature distribution decreases as the gap becomes larger has a tendency that the heat generation density on the outer diameter side of the pot 3 that is a heated container tends to be lower. I understand that.

  In addition, in FIG. 10, according to the pan bottom temperature distribution curve 20 when the gap for three turns is formed, the pan bottom length that falls within 10 ° C. from the predetermined maximum heating temperature of 120 ° C. is 47 mm. Yes, the uniformity is 47%.

  On the other hand, FIG. 12 is a diagram showing a change in the coupling coefficient ratio of the sixth coil to the seventh coil 14 with respect to the gap (for the number of turns) between the sixth coil and the seventh coil 14. Here, the vertical axis is normalized with 1 indicating no gap.

  According to FIG. 12, if a gap for three turns is formed, the coupling coefficient ratio can be reduced to about 0.81, and as a result, the coupling between the sixth coil and the seventh coil 14 becomes weak. The magnetic flux leaking from the seventh coil 14 can be reduced to a level that does not cause a problem in practice.

  Therefore, in the electromagnetic induction heating cooker equipped with the heating coil obtained by the manufacturing method of the second embodiment, if the predetermined uniformity of the pan bottom temperature distribution of the pan 3 allows a slight decrease of 47%. Even if only the inner coil 1 that is the sixth coil is energized to heat the small pot, the magnetic flux leaking from the outer coil 2 that is the seventh coil 14 is reduced. The pot bottom temperature distribution can be heated uniformly with a predetermined degree of uniformity, and the drive circuit can be simplified, and at the same time, for small pots, the reduction in heating efficiency due to magnetic flux leakage can be suppressed. There is an effect that can be done.

  In addition, although it is impossible to use only the inner peripheral coil 1 in response to the small pan, the inner peripheral coil 1 as the sixth coil and the outer peripheral coil 2 as the seventh coil 14 are connected to one drive circuit. The inner coil 1 as the sixth coil and the outer coil 2 as the seventh coil 14 have substantially the same inductance. As a result, the drive efficiency is not lowered, and as a result, the heated container can be heated uniformly, and at the same time, the heating coil can be driven efficiently by simply connecting one drive circuit. The effect that the drive circuit can be simplified is the same as that of the first embodiment.

Embodiment 3 FIG.
In Embodiments 1 and 2, only the case where only one layer of heating coil is mounted on the electromagnetic induction heating cooker is shown. However, depending on the type of the drive circuit, the higher frequency applied when the inductance is increased. Heating efficiency with respect to electric power may be good.

  FIG. 13 is a cross-sectional view of an electromagnetic induction heating cooker in which heating coils are stacked in two layers. By stacking in two layers, the inductance can be increased to a square of 2, and then, The same effects as those of the first and second embodiments can be obtained.

  Further, the number of layers is not limited to two, and it goes without saying that the number of layers may be further increased when the inductance is further increased.

It is sectional drawing of an electromagnetic induction heating cooking appliance provided with the heating coil of Embodiment 1 designed with the manufacturing method of the heating coil which concerns on this invention. It is a top view of the heating coil for demonstrating in detail the structure of the heating coil of Embodiment 1 designed with the manufacturing method of the heating coil which concerns on this invention. FIG. 3 is a process flow diagram showing a procedure for manufacturing the heating coil of the first embodiment. It is a top view of the 1st coil for explaining the 1st process. It is a top view of the 4th coil for explaining the 2nd process. It is a top view of the 4th coil for explaining the 3rd process. It is a top view of the heating coil obtained by designing with the process flow shown in FIG. In a 2nd process, it is a pan bottom temperature distribution figure of the pan radial direction of the pan 3 calculated | required by changing the combination of the 1st division | segmentation position 8 and the 2nd division | segmentation position 9. FIG. It is an inductance characteristic figure which shows the relationship of the magnitude | size of the inductance per turn with respect to the outer diameter of a heating coil. It is a pan bottom temperature distribution figure of the pan radial direction of the pan 3 at the time of changing the clearance gap between the outer peripheral side of a 6th coil, and the inner peripheral side of the 7th coil 14. FIG. FIG. 11 is a pan bottom heat generation density distribution diagram in the pan radial direction corresponding to FIG. 10. It is a figure which shows the change of the coupling coefficient ratio of the 6th coil and the 7th coil 14 with respect to the clearance gap (for the number of turns) between the 6th coil and the 7th coil. It is sectional drawing of the electromagnetic induction heating cooking appliance which laminated | stacked and mounted the heating coil in two layers.

Explanation of symbols

1 inner coil 2 outer coil 3 pan 7 first coil 7a first conductor 7b second conductor 7c third conductor 8 first divided position 9 second divided position 10 second coil 11 third coil Coil 12 Third division position 13 Fifth coil 14 Seventh coil

Claims (6)

In the method of manufacturing a heating coil of an electromagnetic induction heating cooker that energizes the heating coil to heat the heated container,
The inner and outer radii of the first coil for constituting the heating coil, the pitch at which the conductors of the first coil are spirally arranged at equal intervals, and the maximum current for energizing the conductor are set. 1 process,
The first coil is divided into a first conducting wire, a second conducting wire, and a third conducting wire at first and second divided positions that are different from each other in order from the inner circumference side to the outer circumference side, The second conductive wire is removed, and a fourth coil connecting the second coil made of the first conductive wire and the third coil made of the third conductive wire is energized to heat the heated container. When the first division is performed, the temperature of the heated container is brought to at least a predetermined maximum heating temperature with the maximum current, and at the same time, the temperature distribution of the heated container is brought to a predetermined uniformity. A second step of setting a position and the second division position;
The third coil is divided into a fourth conducting wire and a fifth conducting wire in a third division position in order from the inner circumference side to the outer circumference side, and a fifth coil composed of the second coil and the fourth conducting wire. A third step of setting the third division position so that the inductance of the sixth coil formed by connecting the coils of the fifth coil and the seventh coil formed of the fifth conductor is substantially the same;
A method for manufacturing a heating coil, comprising:   In the third step, the relationship between the turn number A of the second coil, the turn number B of the fifth coil, and the turn number C of the seventh coil is approximately A: C: B = 13: 6: 10. The method of manufacturing a heating coil according to claim 1, wherein a third division position is set in the heating coil.   After the third step sets the third division position, the connection between the second coil and the fifth coil is released, and a predetermined number of turns in the fourth conductor on the outer peripheral side of the fifth coil. And the second coil and the fifth coil are connected again after adding the predetermined number of turns of the fourth conducting wire on the inner peripheral side. The manufacturing method of the heating coil of any one of Claim 1 or Claim 2. A heating coil of an electromagnetic induction heating cooker that is energized to heat a heated container,
The inner and outer radii of the first coil for constituting the heating coil, the pitch at which the conductors of the first coil are spirally arranged at equal intervals, and the maximum current for energizing the conductor are set,
The first coil is divided into a first conducting wire, a second conducting wire, and a third conducting wire at a first division position and a second division position that are different from each other in order from the inner circumference side to the outer circumference side, The second conductive wire is removed, and the fourth coil in which the second coil made of the first conductive wire and the third coil made of the third conductive wire are connected is energized, and the heated container When the container is heated, the temperature of the heated container is brought to at least a predetermined maximum heating temperature with the maximum current, and at the same time, the temperature distribution of the heated container is brought to a predetermined uniformity. 1 division position and the second division position are set,
The third coil is divided into a fourth conducting wire and a fifth conducting wire in a third division position in order from the inner circumference side to the outer circumference side, and a fifth coil comprising the second coil and the fourth conducting wire. The third division position is set so that the inductance of the sixth coil formed by connecting the coils of the second coil and the seventh coil formed of the fifth conductor is substantially the same.
A heating coil for an electromagnetic induction cooker, comprising the sixth coil and the seventh coil.   The heating coil for an electromagnetic induction heating cooker according to claim 4, wherein the sixth coil and the seventh coil are connected in parallel.   The heating coil of the electromagnetic induction heating cooker according to claim 4, wherein a plurality of heating coils are laminated.

Images