JP2008171585A - Electromagnetic induction heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating device capable of evading concentration of partial heating of a heated material, and making the whole temperature distribution uniform. <P>SOLUTION: In the induction heating device which is equipped with an induction heating coil constituted by winding around a coil conductor in a cylindrical form, the heated material which is placed on the upper face of this induction heating coil, and which is heated by electromagnetic induction by this induction heating coil, and a support column made of conductive material to support this heated material from the lower face, in which this support column is inserted into a hollow part of the center of the induction heating coil, and in which a magnetic body is arranged at least between the inner wall of the induction heating coil and the support column, the upper end of the magnetic body arranged in the induction heating coil is pulled downward from the upper end of the induction heating coil. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an induction heating apparatus in which an object to be heated composed of a conductive material is heated by electromagnetic induction by an induction heating coil to which high-frequency power is supplied.

  A general induction heating apparatus has a configuration as shown in FIGS.

  The induction heating device of FIG. 8 uses an induction heating coil 5a configured by winding a coil conductor into a cylindrical shape as shown in Patent Document 1. When such a cylindrical induction heating coil 5a is used, a rod-like object to be heated 1a made of a conductive material is inserted into the central hollow portion where the magnetic flux generated by the induction heating coil 5a is concentrated and heated. Therefore, very efficient heating can be performed.

  On the other hand, for example, an induction heating apparatus optimal for an electromagnetic cooker as shown in FIG. 9 is conductive on the upper surface of an induction heating coil 5b configured by winding a coil conductor in a flat plate shape. A heated object 1b such as a cooking pan made of a material is placed and induction heated by an induction heating coil 5b. In the case of the induction heating apparatus as shown in FIG. 9, since the magnetic flux generated by the induction heating coil 5b is distributed above and below the heating coil 5b, the heating efficiency tends to be lower than that in the conventional apparatus of FIG. Therefore, it is necessary to focus the magnetic flux in order to increase the heating efficiency. For this reason, in such an induction heating apparatus, a plurality of magnetic bodies 4g made of rod-shaped or flat-plate-like ferrite are dispersedly arranged on the lower surface of the heating coil so as to suppress the downward dispersion of the magnetic flux.

  In addition, the induction heating device that is most suitable for the electromagnetic cooker as shown in FIG. 10 and shown in FIG. 10 is arranged only on the lower surface of the heating coil 5b in the device of FIG. The magnetic body 4g is a magnetic body 4h having a U-shaped cross section surrounding the outer periphery of the heating coil 5b. Thus, when the inner and outer peripheral surfaces and the bottom surface of the heating coil 5b are surrounded by the magnetic material, the dispersion of the magnetic flux generated by the heating coil 5b is further suppressed and the heated object 1b such as a cooking pot is heated. The magnetic flux can be focused and the heating efficiency can be further improved.

  In addition, a column is coupled to the central portion by an induction heating device, and when a flat object to be heated rotatably supported by the column is to be heated, the column is inserted into the hollow portion of the central portion of the heating coil. Because the flat plate portion is positioned on the upper surface of the induction heating coil, the magnetic flux concentrates on the support column, and the support column that does not require heating is heated.

When induction heating is performed on a flat plate-like object to which a rod-shaped column is coupled at the center, as shown in FIG. 11, in order to efficiently heat the plate-shaped item to be heated without heating the column. In addition, a magnetic body 4j is disposed between a support column 2c made of a conductive material that supports the object to be heated 1c inserted through the hollow portion at the center of the cylindrical induction heating coil 5c from the lower surface, and the inner wall of the coil. Japanese Patent Application No. 2006-197200 proposes preventing magnetic flux from passing therethrough.
JP 2005-206906 A JP 2004-327056 A JP 2005-071951 A

  However, if the magnetic body is arranged inside the induction heating coil as in the apparatus of FIG. 11, the magnetic flux tends to concentrate on the portion of the object to be heated 1c facing the magnetic body 4j. As a result, the heating is promoted and the temperature is increased as compared with other portions, and the temperature distribution of the object to be heated cannot be made uniform.

  That is, as shown in FIG. 12 (a), the magnetic flux 6 generated by the induction heating coil is collected in the magnetic body 4j having a small magnetic resistance as shown by the dotted arrow, and from here, the heated object 1c having the shortest distance is collected. Since the portion that faces the magnetic body 4j extends to the object to be heated 1c, the magnetic flux density of this portion increases, and the magnetic flux density of the central portion to which the support 2c of the object to be heated 1c is attached decreases. For this reason, heating of the article 1c to be heated is not uniform, and uneven heating occurs depending on the location. As shown in FIG. 12 (b), the overall temperature of the object to be heated 1c is extremely low at the central portion where the magnetic flux passing therethrough is extremely low, and the portion facing the magnetic body 4j where the magnetic flux is concentrated becomes higher. The overall temperature distribution of the object 1c becomes non-uniform.

  In order to solve such problems, it is an object of the present invention to provide an induction heating device that can avoid the concentration of partial heating of an object to be heated and make the entire temperature distribution uniform. To do.

  In order to solve the above-described problems, the present invention provides an induction heating coil formed by winding a coil conductor in a cylindrical shape, and an object that is placed on the top surface of the induction heating coil and heated by electromagnetic induction by the induction heating coil. A heating material and a support column made of a conductive material that supports the object to be heated from the lower surface are inserted, and the support column is inserted into the hollow portion at the center of the induction heating coil, and at least between the inner wall of the induction heating coil and the column. In the induction heating apparatus in which a magnetic body is disposed, the upper end of the magnetic body disposed in the induction heating coil is lowered below the upper end of the induction heating coil (Claim 1).

  In the above invention, the magnetic body is further disposed on the outer peripheral side of the induction heating coil, and the upper end of the magnetic body disposed on the outer peripheral side of the induction heating coil is raised above the upper end of the induction heating coil. (Claim 2).

  According to the present invention, the magnetic body disposed between the coil inner wall and the support column in the induction heating coil has its upper end lowered below the upper end of the induction heating coil, so that the magnetic flux generated by the induction heating coil Part of the magnetic material passes from the magnetic material to the object to be heated through the support supporting the object to be heated, which is placed on the top surface of the induction heating coil, so that the coupled central part of the object to be heated is also heated. In addition, since the concentration of magnetic flux in the portion of the object to be heated facing the magnetic body is alleviated, the concentrated heating is also reduced, so that the temperature distribution of the object to be heated is made uniform throughout.

  Embodiments of the present invention will be described with reference to examples shown in the drawings.

  FIG. 1 is a perspective view including a longitudinal section showing Embodiment 1 of the present invention. In this figure, reference numeral 1 denotes a plate-like object to be heated made of a conductive metal. The object to be heated 1 is rotatably supported by a conductive metal column 2 coupled to the center of the lower surface. ing. Reference numeral 3 denotes an induction heating coil configured by winding a coil conductor in a cylindrical shape, and is excited by high-frequency AC power supplied from a high-frequency power source (not shown).

  In order to heat the object to be heated 1, the support column 2 is inserted into the center of the inner hollow part 3 a of the induction heating coil 3, and the object to be heated 1 is disposed on the upper surface of the induction heating coil 3. And the magnetic body 4 which consists of ferrite etc. is arrange | positioned between the support | pillar 2 and the inner wall of the induction heating coil 3 in the hollow part 3a of the induction heating coil, and the magnetic flux generated by the induction heating coil 3 is coil hollow. It concentrates on the magnetic body 4 in the part 3a, and does not pass the support | pillar 2 which supports the to-be-heated material 1. FIG.

  The magnetic body 4 may be integrally formed in a cylindrical shape, or may be divided into a plurality of flat bar segments 4a having a planar shape as shown in FIG. It may be arranged in a distributed manner. In addition, the shape of the rod-shaped segment 4a is not limited to the illustrated shape, and may be a rectangular parallelepiped shape. The magnetic body 4 is arranged with the upper end position lowered below the upper end position of the coil 3 by a predetermined dimension A.

  When heating the article 1 to be heated, high frequency AC power is supplied to the induction heating coil 3 from a high frequency power source (not shown), and the coil 3 generates a high frequency magnetic field. As shown in FIG. 1 by a dotted line, a large portion of the magnetic flux 6 formed by the high-frequency magnetic field is a magnetic body 4 of the hollow portion 3a of the coil 3, an outer periphery of the coil 1 and a magnetic circuit of the magnetic body 4. As a result, the object to be heated 1 is heated by the eddy current generated in the object to be heated 1 made of a conductive material by the electromagnetic induction action.

  At this time, the magnetic body 4 inserted between the coil 3 and the support column 2 coupled to the object to be heated 1 serves as a magnetic shield to prevent the magnetic flux from passing through the support column 2. In the present invention, however, the magnetic body 4 comes out of the magnetic body 4 as shown in FIG. 3 (a) by placing it down by a dimension A so as not to go above the induction heating coil. Part of the magnetic flux 6 passes through the column 2 to the article 1 to be heated.

  For this reason, magnetic flux hardly passes so far, heating is weak, and the magnetic flux density of the coupling portion of the column 2 at the center of the article 1 to be heated has been increased, heating of this portion is increased, and the temperature is increased. Enhanced. Further, since the magnetic flux directly passing from the magnetic body 4 to the object to be heated 1 is dispersed and the concentration is reduced, the temperature rise of the portion of the object to be heated 1 facing the magnetic body 4 is suppressed. Thereby, the temperature distribution of the whole to-be-heated material 1 is improved, and it becomes substantially uniform as shown in FIG.

  FIG. 4 shows a second embodiment of the present invention. In the second embodiment, a magnetic body 4 made of ferrite or the like inserted between the induction heating coil 3 and the column 2 supporting the article 1 to be heated is inserted into the coil hollow portion 3 a and extends in parallel with the column 2. The point which equips the lower surface of the coil 3 with the horizontal member 4c arrange | positioned horizontally besides the vertical member 4b is different from Example 1. FIG.

  As described above, when the magnetic member 4 is provided with the horizontal member 4c extending horizontally on the lower surface side of the coil 3, the magnetic flux diffused below the induction heating coil 3 is focused by the horizontal member 4c of the magnetic member. As a result, since the amount of magnetic flux passing through the article to be heated 1 can be increased, the heating efficiency of the article to be heated 1 can be increased as compared with that in the first embodiment.

  The magnetic body 4 may be integrally configured as a cylindrical body with a hook, but as shown in FIG. 5, a plurality of segmented segments 4d having an L-shaped cross section are arranged side by side on the circumference. You can also.

  And the vertical member 4b part and the horizontal member 4c part of the magnetic body 4 are not comprised integrally as shown in FIG. 6, but are divided | segmented and comprised so that the suitable space | gap g may be provided between both members. To. If the integrated structure is adopted, the magnetic flux is concentrated at the corner portion where the vertical member 4b and the horizontal member 4c are combined, so that the magnetic flux density is increased and the magnetic flux saturation phenomenon occurs. Since the magnetic resistance at the corner increases and the concentration of the magnetic flux is suppressed, it is possible to suppress the occurrence of the magnetic flux saturation phenomenon.

  FIG. 7 shows Embodiment 3 of the present invention. In Example 3, a magnetic body 4 made of ferrite or the like inserted between the induction heating coil 3 and the support 2 supporting the article 1 to be heated was inserted into the coil hollow portion 3 a and extended in parallel with the support 2. The point which is provided with the vertical member 4d arrange | positioned at the outer periphery of the coil 3 in addition to the vertical member 4b and the horizontal member 4c arrange | positioned horizontally at the lower surface of the coil 3 is different from Example 1 and 2. FIG. .

  The upper end of the vertical member 4d is raised above the upper end of the coil 3 by a predetermined dimension B. The upper end of the vertical member 4b disposed in the coil 3 is lowered downward by a predetermined dimension A from the upper end of the coil 3 as in the first and second embodiments.

  The magnetic body 4 in the third embodiment can be integrally formed in a double cylinder shape, or can be divided into segments having a U-shaped cross section.

  According to the third embodiment, the vertical member 4b of the magnetic body 4 in the coil 3 not only improves the temperature distribution in the central portion of the article 1 to be heated, but also the outer periphery of the coil 3 as in the first and second embodiments. The magnetic vertical member 4d disposed in the magnetic field increases the magnetic flux density in the vicinity of the outer peripheral end of the object 1 to be heated, and the temperature distribution in the vicinity can be improved. Therefore, as shown in FIG. The entire temperature distribution of 1 can be made more uniform. And since the magnetic flux disperse | distributed to the outer side of the coil 3 can be converged by the perpendicular | vertical member 4d of this magnetic body, heating efficiency can be improved more.

It is a perspective view including the longitudinal cross-section which shows the structure of the induction heating apparatus by Example 1 of this invention. It is a top view of the lower surface of the induction heating apparatus by Example 1 of this invention. It is an operation explanatory view of Example 1 of this invention, (a) is an explanatory view of distribution of magnetic flux, and (b) is a characteristic line figure showing a temperature distribution characteristic of a diameter direction of a thing to be heated. It is a perspective view containing the longitudinal cross-section which shows the structure of the induction heating apparatus by Example 2 of this invention. It is a perspective view including the longitudinal cross-section which shows the modification of the magnetic body used in Example 2 of this invention. It is a perspective view containing the longitudinal cross-section which shows the other modification of the magnetic body used in Example 2 of this invention. Example 3 of this invention is shown, (a) is a perspective view including the longitudinal section which shows the structure, (b) is a characteristic diagram which shows the temperature distribution characteristic of the diameter direction of a to-be-heated material. It is a perspective view which shows schematic structure of the conventional 1st induction heating apparatus. It is a longitudinal cross-sectional view which shows schematic structure of the conventional 2nd induction heating apparatus. It is a longitudinal cross-sectional view which shows schematic structure of the conventional 3rd induction heating apparatus. It is a perspective view containing the longitudinal cross-section which shows schematic structure of the conventional 4th induction heating apparatus. It is operation | movement explanatory drawing of the conventional 4th induction heating apparatus, (a) is explanatory drawing of distribution of magnetic flux, (b) is a characteristic diagram which shows the temperature distribution characteristic of the diameter direction of a to-be-heated material.

Explanation of symbols

1: Heated object 2: Support column 3: Induction heating coil 4: Magnetic material

Claims (2)

  An induction heating coil formed by winding a coil conductor in a cylindrical shape, an object to be heated by electromagnetic induction by the induction heating coil, and the object to be heated supported from the lower surface. In an induction heating apparatus comprising a support made of a conductive material, and inserting the support into a hollow portion at the center of the induction heating coil, and at least arranging a magnetic material between the inner wall of the induction heating coil and the support, An induction heating apparatus, wherein an upper end of the magnetic body disposed in the induction heating coil is lowered below an upper end of the induction heating coil.   2. The induction heating apparatus according to claim 1, wherein the magnetic body is further disposed on an outer peripheral side of the induction heating coil, and an upper end of the magnetic body disposed on the outer peripheral side of the induction heating coil is above the upper end of the induction heating coil. An induction heating device characterized in that it is raised.

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