JP2005129350A - Electromagnetic induction heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic induction heating apparatus that provides the uniform distribution of a heating force to a heated element, thus enabling the heated element to be heated evenly by solving the problem that, conventionally, crude density in magnetic flux is generated in a common single coil resulting from a mutual influence between generated fluxes, thus precluding the heated element to be heated evenly. <P>SOLUTION: In an electromagnetic induction heating apparatus in which a spiral type heating coil 2 generates an eddy current on a heated element 1, thus heating the heated element 1, the apparatus is configured such that the heating coil 2 is divided into a plurality of sections, and these divided coils 4 to 7 are arrayed adjacent to one another. As a result, since the heating coil 2 is divided into the plurality of sections, and these divided coils 4 to 7 are arrayed adjacent to one another, crude density in magnetic flux is suppressed, and the magnitude of the eddy current generated on the heated element 1 is averaged, thus enabling the heated element 1 to be heated evenly. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

    The present invention relates to an electromagnetic induction heating device that induction-heats an object to be heated by a spiral heating coil.

  The electromagnetic induction heating device is an apparatus that induces eddy current by causing the magnetic flux of the heating coil to interlink with the heated body by flowing an alternating current through the heating coil, and heats the heated body due to resistance loss. A coil using a spiral coil is suitable for heating a flat plate-like object to be heated, and is applied to, for example, an electromagnetic cooker described in Patent Document 1.

  FIG. 7 is a principle view of a conventional electromagnetic induction heating device for heating a plate material such as an iron plate, FIG. 7A is a plan view, FIG. 7B is a cross-sectional view taken along line BB in FIG. ) Is a cross-sectional view along the line C-C. In FIG. 7, a spiral heating coil 2 is arranged with a gap in parallel with the heated body 1 made of a plate-like magnetic material, and the heating coil 2 is connected to an electromagnetic induction power source 3. Now, when an alternating current is supplied from the power source 3 to the heating coil 2, the magnetic flux of the heating coil 2 is linked to the heated body 1, and an eddy current is generated in the range shown by hatching in FIG. The heating element 1 generates heat due to resistance loss.

JP 2002-43043 A

  The curves indicated by the alternate long and short dash lines in FIGS. 7B and 7C show the distribution of the heating force (eddy current) of the heating coil 2 with respect to the heated object 1. The magnetic flux generated by the heating coil 2 causes the density of the magnetic flux density to become coarse and dense in the plane of the heated body 1 due to the influence of the mutual magnetic flux, and the eddy current flowing through the heated body 1 is roughly proportional to the magnetic flux density and has a large portion and a small portion. As a result, as shown in the figure, the eddy current decreases toward the end of the winding width with the vicinity of the approximate center of the coil winding width (illustrated w) as the apex, and the heated body 1 is heated to the donut state. Therefore, the temperature distribution in the plane becomes non-uniform, and the heated object 1 is distorted, or the heating of the object placed on the heated object 1 is made non-uniform.

  An object of the present invention is to make the distribution of the heating force applied to the object to be heated by the heating coil uniform, thereby heating the object to be heated evenly.

  In order to solve the above-described problems, the present invention provides an electromagnetic induction heating apparatus for heating an object to be heated by generating an eddy current in the object to be heated by a spiral heating coil, and dividing the heating coil into a plurality of parts. These divided coils are arranged next to each other (claim 1).

  A conventional heating coil is generally single, and even if it is divided into several parts, as shown in, for example, Patent Document 1 described above, these divided coils are arranged concentrically with each other. In such a conventional configuration, the density of the magnetic flux becomes dense due to the influence of the generated magnetic fluxes, and the heating force is large and small as described above, so that the object to be heated cannot be heated uniformly. In the first aspect of the present invention, the heating coil is divided into a plurality of coils, and these divided coils are arranged adjacent to each other. Thereby, the density phenomenon of the magnetic flux density is alleviated, and the magnitude of the eddy current generated in the heated body is averaged to realize uniform heating of the heated body.

  In the invention of claim 1, the current directions of the two adjacent divided coils are opposite to each other (invention 2). Thereby, the fall of the heating force by interference of the eddy current of adjacent heating coils can be avoided.

  In the second aspect of the present invention, only the specific two adjacent divided coils may have the same current direction so as to change the heating power distribution with respect to the object to be heated (claim 3). For example, the temperature tends to rise because heat tends to collect in the central portion of the heated object. In that case, if the current directions of the two divided coils positioned in the center portion of the heated body are made the same, the eddy currents having different directions interfere with each other in the middle of the two divided coils, and the heating power becomes weaker. The rise is mitigated.

  In the invention of claim 2 or claim 3, a plurality of the divided coils may be connected in series with each other, and the connection direction at both ends of the divided coils may be changed to determine the direction of the current. .

  In the first aspect of the invention, the distribution of the heating force with respect to the heated body can be changed by changing the distance between each of the divided coils and the heated body (invention 5). In that case, a part of the divided coil can be bent and separated from the object to be heated, and the distance between this part and the object to be heated can be changed.

  In the first aspect of the present invention, the distribution of the heating force with respect to the object to be heated may be changed by changing the winding density of each of the divided coils (invention 7).

  In the first aspect of the present invention, the heating coil made of bare wire may be held by an inorganic high heat resistant insulator and fixed to the object to be heated via the insulator (invention 8). Even when the heating coil is brought close to the heated body to adjust the temperature distribution by using a bare wire, even in a short distance where the dielectric strength is impaired by radiant heat from the heated body in normal coil insulation. The risk of damage to the heating coil is eliminated.

  According to the present invention, the heating coil is divided into a plurality of parts, and these divided coils are arranged adjacent to each other, thereby averaging the strength of the heating force in the single coil and equalizing the temperature distribution of the object to be heated as a whole. Can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In addition, the same code | symbol shall be used for the part corresponding to a prior art example.

  FIG. 1 shows Example 1 as a basic embodiment of the present invention. FIG. 1A is a plan view of a heating device, and FIG. 1B is a sectional view taken along line BB in FIG. , (C) is a cross-sectional view along the line CC. In FIG. 1, the heating coil 2 is divided into a plurality (four in the drawing) of elliptical flat divided coils 4 to 7, and these divided coils 4 to 7 are adjacent to the object to be heated 1 so as to be adjacent to each other. They are arranged in parallel and with a gap to be heated 1. In addition, adjacent divided coils are connected to the electromagnetic induction power source 3 in series with each other divided coils 4 to 7, where the winding start of one divided coil 4 to 7 is connected to the winding end of the other divided coil 4 to 7. The directions of the currents are alternately reversed as indicated by arrows.

  The heating power (eddy current) whose range is indicated by hatching in FIG. 1 (A) is distributed with the strength shown by the one-dot chain line in FIGS. 1 (B) and 1 (C). First, with respect to the arrangement direction of the divided coils 4 to 7 (vertical direction in FIG. 1), there are a plurality of eddy current peaks at the vertices between adjacent coils in which the eddy currents by the divided coils 4 to 7 strengthen each other (not shown). 3), and smaller peaks are formed at the upper and lower ends of FIG. That is, by dividing the heating coil 2 into a plurality of parts, a plurality of eddy current distribution peaks (five in the figure) are generated, and their magnitudes are smaller than those of a single coil. As a result, the strength of the heating force in the width direction (up and down direction in FIG. 1) of the heated body 1 is relaxed compared to the single coil (FIG. 7), and the temperature distribution is also equalized gently.

  Moreover, about the longitudinal direction (left-right direction of FIG. 1) of the split coils 4-7, although two peaks which become a vertex at the approximate center of the winding width of both ends arise, the number of turns of each split coil 4-7 is single. Since there are fewer than coils, the peaks are also smaller than a single coil. As a result, the temperature distribution in the vertical direction (the left-right direction in FIG. 1) of the heated body 1 is also equalized gently.

  In the first embodiment, the divided coils are arranged only in the vertical direction of FIG. 1, but it is possible to further subdivide into a large number of divided coils and spread them in the front, rear, left and right to obtain a more uniform temperature distribution. On the other hand, in Example 1, the surface facing the heating coil of the object to be heated is a flat surface. However, by dividing the heating coil, the divided coil can be applied to the object to be heated having a complicated shape such as a cylindrical surface or a spherical surface. The heating efficiency can be improved as compared with the case where the single coil is deformed in accordance with the object to be heated.

  The above-mentioned heated object with uniform temperature distribution can be heated evenly to every corner when applied to grilled food cooking process, for example, okonomiyaki iron plate. You can put the pieces and cook at the same time. In addition, since the surface of the object to be heated can be heated evenly, the surface heat treatment of metal, etc. is homogenized, and direct drying after washing of metal parts that can be induction-heated and fibers, leather products, paper, etc. are spread on the iron plate It becomes possible to heat and dry. On the other hand, since heating can be performed uniformly, even if the thickness of the heated object is thin, thermal strain hardly occurs. Therefore, the heated object can be thinned to reduce the weight.

  2A and 2B show a second embodiment of the present invention, in which FIG. 2A is a plan view of a heating device, FIG. 2B is a cross-sectional view taken along line BB in FIG. 2A, and FIG. It is sectional drawing which follows a C line. The second embodiment is different from the first embodiment in that the connection between the two split coils 5 and 6 at the center is changed. Normally, the temperature of the central portion of the heated body is likely to rise because the heat generated around is collected. In order to alleviate this phenomenon, it is preferable to cause the eddy current to interfere between adjacent divided coils and to reduce the heating power at the center.

  Example 2 shows such an example. In FIG. 2, adjacent divided coils 5 and 6 are connected at the beginning and end of winding, and the current directions of the coils are the same as indicated by arrows. Yes. As a result, the eddy currents cancel each other between the split coil 5 and the split coil 6, and the peak of the central peak of the eddy current is suppressed as shown by the one-dot chain line in FIG. Thereby, the heat_generation | fever of the center part of the to-be-heated body 1 reduces, and the excessive temperature rise by the movement of the heat | fever from a peripheral part is suppressed.

  3A and 3B show a third embodiment of the present invention, in which FIG. 3A is a plan view of the heating device, and FIG. 3B is a sectional view taken along line BB in FIG. Example 3 shows an example in which the distribution of the heating force with respect to the heated body is changed by changing the distance between each divided coil and the heated body. As described above, the temperature of the central portion of the heated object is likely to rise. Therefore, in FIG. 3, the two split coils 5 and 6 at the center are installed such that the distance from the heated body 1 is farther than the split coils 4 and 7 on both sides. As the distance between the divided coils 4 and 7 and the heated body 1 increases, the magnetic flux density interlinking with the heated body 1 decreases, and the temperature rise at the center of the heated body 1 is suppressed.

  4A and 4B are plan views of a heating apparatus showing Embodiment 4 of the present invention. FIG. 4A shows a case where both ends of the heating coil are coarsely wound, and FIG. Since the magnetic flux tends to concentrate at the end of the heating coil having a large winding curvature, the heating power tends to increase. In order to suppress this heating force, as shown in FIG. 4A, it is preferable to widen the interval between the windings by roughly winding the end 2a. Thereby, a heating force is disperse | distributed and an excessive temperature rise is suppressed. On the other hand, the end of the object to be heated tends to be low in temperature because heat dissipation increases. In this case, as shown in FIG. By narrowing the interval, the heating power can be concentrated and the temperature rise can be promoted.

  FIG. 5 is a side view of a heating apparatus showing Embodiment 5 of the present invention. The fifth embodiment shows an example in which a part (end portion) 2a of the split coil is bent as another means for reducing the heating power at the end portion of the heating coil 2. FIG. As shown in the figure, the end 2a is bent and separated from the heated body 1, thereby reducing the magnetic flux density interlinked with the heated body 1 at this portion, and increasing in the same manner as in the embodiment of FIG. The temperature can be suppressed.

  6A and 6B show a sixth embodiment of the present invention, in which FIG. 7A is a plan view of a heating device, FIG. 6B is a cross-sectional view taken along line B-B in FIG. FIG. When adjusting the distance to the object to be heated for each divided coil in order to adjust the heating power, some divided coils may be very close to the object to be heated. With normal coil insulation, there is a risk of loss of dielectric strength. Therefore, in Example 6 of FIG. 6, bare wires (copper wires) that are not insulated are used as they are for the divided coils 4 to 7. These divided coils 4 to 7 are held by an inorganic high heat-resistant insulator 8 such as ceramic or ceramic, and as shown in FIG. It is fixed. By using a bare wire, there is no fear that the heating coil 2 may be damaged even at a short distance where the dielectric strength is impaired by the radiant heat from the heated body 1 in normal coil insulation.

Example 1 of this invention is shown, (A) is a plan view of a heating device, (B) is a sectional view taken along line BB in (A), and (C) is a sectional view taken along line CC as well. is there. Example 2 of this invention is shown, (A) is a plan view of the heating device, (B) is a cross-sectional view taken along the line BB of (A), and (C) is a cross-sectional view taken along the line C-C. is there. Example 3 of this invention is shown, (A) is a top view of a heating apparatus, (B) is sectional drawing which follows the BB line of (A). It is a top view of the heating apparatus which shows Example 4 of this invention, (A) is a case where both ends of a heating coil are coarsely wound, and (B) is a case where it is also densely wound. It is a side view of the heating apparatus which shows Example 5 of this invention. Example 6 of this invention is shown, (A) is a plan view of the heating device, (B) is a sectional view taken along line BB in (A), and (C) is a partially enlarged view of (B). . The conventional heating apparatus is shown, (A) is a top view, (B) is sectional drawing which follows the BB line of (A), (C) is sectional drawing which follows the CC line similarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 To-be-heated body 2 Heating coil 3 Electromagnetic induction power supply 4-7 Split coil 8 Insulator

Claims (8)

In an electromagnetic induction heating apparatus that generates an eddy current in a heated object by a spiral heating coil and heats the heated object,
An electromagnetic induction heating apparatus, wherein the heating coil is divided into a plurality of parts and the divided coils are arranged adjacent to each other.   2. The electromagnetic induction heating device according to claim 1, wherein current directions of two adjacent divided coils are opposite to each other.   3. The electromagnetic induction heating apparatus according to claim 2, wherein only two specific adjacent divided coils have the same current direction so as to change a heating power distribution with respect to the object to be heated.   4. The electromagnetic induction according to claim 2, wherein a plurality of the divided coils are connected in series with each other, and the direction of the current is determined by changing a connection relation between both ends of the divided coils. Heating device.   2. The electromagnetic induction heating device according to claim 1, wherein the distribution of the heating force with respect to the object to be heated is changed by changing the distance between each of the divided coils and the object to be heated.   6. The electromagnetic induction heating apparatus according to claim 5, wherein a part of the divided coil is bent to change a distance between the part and the object to be heated.   2. The electromagnetic induction heating apparatus according to claim 1, wherein the distribution of the heating force with respect to the object to be heated is changed by changing the winding density of each of the divided coils. 2. The electromagnetic induction heating apparatus according to claim 1, wherein the heating coil made of a bare wire is held by an inorganic high heat resistant insulator, and the heating coil is fixed to the object to be heated via the insulator. .

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