JP2005304759A - Rice cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rice cooker capable of easily reducing low-frequency leaking magnetic fields included in a heating coil. <P>SOLUTION: A coiled wire 12 through which an electric current with the same frequency component as the low-frequency component of the current running in the heating coil 1 runs in the opposite direction from the heating coil 1 is disposed near the heating coil 1 inside an invertor 11. The low-frequency leaking magnetic fields can be significantly reduced as the low-frequency magnetic fields generated from the coiled wire 12 offset the low-frequency magnetic fields generated from the heating coil 1 each other. Furthermore, the coiled wire 12 can be easily manufactured without preparing any special winding tool by disposing the coiled wire 12 on the outer surface of an inner frame 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an induction heating rice cooker used for home use and business use.

  In a conventional induction heating rice cooker, an induction heating apparatus (see, for example, Patent Document 1) will be described with reference to the drawings as a method for reducing a leakage magnetic field from a heating coil. FIG. 9 shows a conventional induction heating apparatus in which the leakage magnetic field of the heating coil is reduced. In this conventional example, an electromagnetic shield ring 2 is arranged on the outer peripheral portion of the heating coil 1 to constitute an induction heating device. In the induction heating apparatus having this configuration, an induction current flows through the electromagnetic shield ring 2 by being induced by the high-frequency magnetic field generated in the heating coil 1, and further, the induction current causes a high-frequency magnetic field generated from the heating coil 1 to be generated in the electromagnetic shield ring 2. Produces a reverse high-frequency magnetic field. As a result, the high-frequency magnetic field generated from the electromagnetic shield ring 2 acts so as to cancel the high-frequency magnetic field generated at the outer periphery of the heating coil 1, so that the high-frequency leakage magnetic field of about 20 k to 100 kHz leaking from the heating coil 1 is reduced. . The electromagnetic shield ring 2 is known to have an aluminum plate, a lead wire or the like made into a ring.

An induction heating apparatus (see, for example, Patent Document 2) that reduces a leakage magnetic field generated from another heating coil will be described. FIG. 10 shows a conventional induction heating apparatus with a reduced leakage magnetic field. The inductance 5 is formed by winding the vicinity of the outer periphery of the heating coil 1, and the high-frequency magnetic field generated from the heating coil 1 and the high-frequency magnetic field component generated by the inductance 5 are arranged to cancel each other. FIG. 11 shows a circuit example of a conventional induction heating apparatus. The induction heating device of FIG. 11 includes a power supply unit 3 configured by a commercial power source, an inverter 11 that converts power of the power supply unit 3 into high-frequency power, a heating coil 1 that converts power of the inverter 11 into a high-frequency magnetic field, and the heating coil 1. The inverter 11 includes a rectifier 4 that rectifies the commercial power supply, an inductor 5 that smoothes the output of the rectifier 4, a smoothing capacitor 6, and power to the heating coil 1. The semiconductor switch 8 is configured to control supply, and the resonance capacitor 7 is configured to smooth the switching operation of the semiconductor switch 8. In the conventional example shown in FIG. 10, the inductor 5 is composed only of windings, which eliminates the need for the core material of the inductance 5, thereby reducing the size of the device and simultaneously reducing the high frequency noise.
JP-A-57-115795 Japanese Patent Publication No. 63-7672

  However, in the induction heating apparatus in which the leakage magnetic field from the conventional heating coil 1 as shown in FIG. 9 is reduced, the high-frequency leakage magnetic field can be reduced by the effect of the electromagnetic shield ring 2, but is generated from the heating coil 1. This is because the power source frequency or magnetic field twice the frequency of the power source (hereinafter referred to as a low frequency magnetic field) is hardly absorbed by the pan 15 and the electromagnetic shield ring 2 cannot sufficiently generate a reverse magnetic field. Is released to the outside without decreasing.

  On the other hand, in the conventional induction heating apparatus of FIGS. 10 and 11, since the winding is operated as an inductance (about several hundred μH), the number of turns of the winding increases. At this time, the low-frequency magnetic field emitted from the winding becomes larger than the low-frequency magnetic field emitted from the heating coil, resulting in an increase in the low-frequency magnetic field emitted to the outside. In addition, the conventional induction heating device aims to cancel the high-frequency magnetic field, and the winding for reducing the leakage magnetic field is limited to the vicinity of the heating coil and has no freedom of arrangement, and is further arranged near the heating coil. The magnetic field distribution to the heated object such as changes, particularly in the case of a rice cooker, the problem of greatly affecting the rice cooking performance arises. Further, as described above, the conventional induction heating apparatus reduces the high-frequency leakage magnetic field, and has not paid attention to the reduction of the low-frequency leakage magnetic field. However, by reducing the low-frequency leakage magnetic field, the user's anxiety about the effects on the human body of the low-frequency magnetic field, which is not clear in the causal relationship but is concerned in some investigations, can be removed. It is also possible to eliminate the risk of malfunction of an electronic device in the immediate vicinity of.

  In order to solve the above-mentioned problems, the present invention focuses on a low-frequency leakage magnetic field that has not been recognized by a conventional induction heating rice cooker, and reduces the emission of a low-frequency magnetic field from a heating coil. And reduce unnecessary electromagnetic waves generated from the equipment, and low frequency leakage magnetic field without adversely affecting rice cooking performance by taking low frequency leakage magnetic field countermeasures without greatly changing the magnetic field distribution of conventional induction heating rice cookers It aims at providing the rice cooker which can take measures.

  In order to solve the above-mentioned problems, a rice cooker of the present invention supports a side surface of a pan in a pan, a heating coil for induction heating the pan, a coil frame for installing the heating coil, and an upper portion of the coil frame. An inner frame, a plurality of first magnetic bodies disposed in opposition to the pan near the back surface of the heating coil, an inverter for supplying a high-frequency current including a commercial frequency component to the heating coil, and the heating coil A coil-like wiring arranged in a coil shape in the vicinity of the heating coil so that a current having a current component having the same frequency as the current of the flowing commercial frequency component flows in a direction opposite to the heating coil; By arranging the coiled wiring around the circumference, the coiled wiring is arranged so that the current flows in the opposite direction to the heating coil at the same frequency component as the low frequency component flowing in the heating coil. The magnetic field generated from the coil cancels each other with the low-frequency leakage magnetic field from the heating coil, thereby greatly reducing the leakage magnetic field and winding the coiled wiring around the inner frame. Since there is no need to provide a separate winding jig, coiled wiring can be easily arranged.

  The rice cooker of the present invention has little influence on the rice cooking performance and can reduce the low-frequency leakage magnetic field generated from the heating coil.

  The first invention includes a pan, a heating coil for inductively heating the pan, a coil frame for installing the heating coil, an inner frame at the top of the coil frame and supporting a side surface of the pan, and the heating coil. The same as the current of the commercial frequency component flowing in the heating coil, the first magnetic body disposed in the vicinity of the back surface and facing the pan, the inverter supplying a high-frequency current containing the commercial frequency component to the heating coil A coil-shaped wiring arranged in a coil shape in the vicinity of the heating coil such that a current having a frequency current component flows in a direction opposite to the heating coil; and the coil-shaped wiring is arranged on the outer periphery of the inner frame. The magnetic field generated from the coiled wiring arranged so that the current flows in the opposite direction to the heating coil with the same frequency component as the low frequency component flowing in the heating coil is The leakage magnetic field is greatly reduced by canceling each other with the low-frequency leakage magnetic field from the coil, and it is necessary to provide a winding jig for winding the coiled wiring by winding the coiled wiring around the inner frame. Therefore, coiled wiring can be easily arranged.

  In the second invention, in particular, the rice cooker of the first invention is provided with a convex portion on the outer peripheral portion of the inner frame, and the coil-shaped wiring is arranged in tandem above the convex portion. Since it becomes difficult to disengage from the inner frame, the position of the coiled wiring can be correctly determined, and a stable magnetic shielding effect can be obtained.

  3rd invention arrange | positions the 2nd magnetic body above the said 1st magnetic body especially in the coil-shaped wiring vicinity in the rice cooker of any one of 1st-2nd invention, and is on the inner-frame outer periphery. By configuring the second magnetic body to be fixed, the magnetic field generated from the coiled wiring can be prevented from radiating to the first magnetic body, and the magnetic performance of the first magnetic body can be reduced. While the rice cooking performance deterioration by a change can be prevented, the position of a 2nd magnetic body can be determined accurately.

  According to a fourth aspect of the invention, in particular, the rice cooker of the third aspect is provided with a bent portion in the second magnetic body, and a coiled wiring is disposed above the bent portion of the second magnetic body. Since the second magnetic body is also disposed below the coiled wiring, it is possible to further suppress the magnetic field generated from the coiled wiring from radiating to the first magnetic body. Rice cooking performance deterioration due to changes in the magnetizing performance of the body can be prevented.

  According to a fifth aspect of the invention, in particular, the rice cooker according to the third aspect of the invention is further provided with a configuration in which a plurality of bent portions are provided in the second magnetic body, and a coil-shaped wiring is sandwiched between the second magnetic bodies. It can suppress more that the magnetic field which generate | occur | produces from a shape-like wiring radiates | emits to a 1st magnetic body, and can prevent the rice cooking performance deterioration by the change of the magnetic performance of a 1st magnetic body.

  According to a sixth aspect of the present invention, in particular, the rice cooker according to the third aspect of the present invention is provided by disposing the third magnetic body on the outer peripheral side of the coiled wiring so as to face the second magnetic body. The magnetic body and the third magnetic body remain in a plate shape, and the magnetic field generated from the coiled wiring can be prevented from radiating to the first magnetic body, and the first magnetic body can be magnetized. Rice cooking performance deterioration due to performance changes can be prevented.

(Embodiment 1)
FIG. 1 shows a block diagram of a rice cooker in an embodiment of the present invention. In FIG. 1, a power supply unit 1 including a commercial power supply is connected to an inverter 11, and the inverter 11 is connected to the heating coil 1. The heating coil 1 is disposed on the bottom and side surfaces of the coil frame 14 and is installed in a magnetically coupled manner with the pan 15 placed on the top surface of the coil frame 14. A first magnetic body 13 made of a magnetic body such as ferrite that enhances magnetic coupling with the pan 15 is disposed below the heating coil 1. An inner frame 16 is disposed above the coil frame 14, and the pan 15 is disposed on the coil frame 14 along the inner frame 16. The inverter 11 includes a rectifier 4 connected to the power supply unit 3, a series connection of an inductor 5 and a smoothing capacitor 6 connected in series with the rectifier 4, and a resonant capacitor 7 connected in parallel to the smoothing capacitor 6. The resonance capacitor 7 is connected in parallel with the heating coil 1. The wiring from the inductor 5 is wound a plurality of times in a coil shape opposite to the winding direction of the heating coil 1 (hereinafter referred to as a coil-shaped wiring 12) and disposed on the inner frame 16.

  FIG. 2 is a diagram showing a positional relationship between the coiled wiring 12 and the inner frame 16 in the embodiment of the present invention. The coil-shaped wiring 12 is wound around the outer periphery of the inner frame 16 and arranged. Further, since the inner frame 16 is located above the coil frame 14, the coil-shaped wiring 12 is disposed on the substantially outer periphery of the heating coil 1.

  About the rice cooker comprised as mentioned above, the operation | movement and an effect | action are demonstrated below. FIG. 3 is a diagram showing a current path in each section of the inverter circuit. I3 indicates an input current, I5 indicates a current flowing through the inductor 5 and the coiled wiring 12, and I1 indicates a current flowing through the heating coil 1. The power supply unit 3 is composed of a commercial power source or the like, and supplies commercial frequency power to the inverter 11. Therefore, the input current I3 is a current having a commercial frequency component. In the inverter 11, the commercial power is rectified by the rectifying means 4 and converted into power having a frequency component twice that of the commercial power supply, and further converted into high-frequency power of about 20 k to 100 kHz using the semiconductor switch 8. This high frequency power is supplied to the heating coil 1 and supplied from the heating coil 1 to the pan 15 in the form of a high frequency magnetic field. In the pan 15, an eddy current is generated in the surface layer portion by the supplied high-frequency magnetic field, and as a result, heat is generated. Therefore, a current I5 having a frequency twice the commercial frequency flows through the inductor 5 and the coiled wiring 12, and when the semiconductor switch 8 is turned on in the heating coil 1, the power supply unit 1 → rectifying means A current I11 in which a low frequency current having a component twice the commercial frequency generated in the loop of 4 → heating coil 1 → semiconductor switch 8 and a high frequency component flowing in the heating coil 1 according to the frequency of the semiconductor switch 8 flows. Therefore, the low frequency magnetic field generated from the heating coil 1 can be canceled by arranging the heating coil 1 and the coiled wiring 12 so that the low frequency magnetic fields cancel each other.

  On the other hand, by winding the coil-shaped wiring 12 around the inner frame 16, it is not necessary to prepare and wind a winding jig in particular, and the shape is stabilized. In addition, since the coil-shaped wiring is arranged on the outer peripheral portion and the upper portion of the heating coil 1, the coil-shaped wiring 12 that generates a canceling magnetic field is arranged around the outer peripheral portion where more low-frequency magnetic fields are generated. The low-frequency magnetic field radiated to the outside from the heating coil 1 can be canceled more.

  Furthermore, as shown in FIG. 4, a convex portion is provided at the lower end of the inner frame 16 and the coil-shaped wiring 12 is provided on the upper portion thereof, and the coil-shaped wiring 12 can be positioned by arranging them in a column. Thus, it is possible to prevent the coiled wiring 12 from being detached from the inner frame 16.

  In the present embodiment, a general circuit configuration used for the induction heating apparatus is shown. However, if the circuit configuration is such that the heating coil 1 is superposed with a commercial frequency and a current having a frequency component twice the commercial frequency. There is no particular limitation.

  As described above, in the present embodiment, a coil is formed in the vicinity of the heating coil 1 so that the current flows in the opposite direction to the heating coil 1 with the same frequency component as the low frequency component of the current flowing in the heating coil 1 in the inverter 11. The coil-shaped wiring 12 disposed in the center of the coil-shaped wiring 12 cancels each other with the low-frequency magnetic field from the heating coil 1 due to the low-frequency magnetic field generated from the coil-shaped wiring 12, and greatly reduces the low-frequency leakage magnetic field. By adopting a configuration in which the coil-shaped wiring 12 is wound on 16, it is not necessary to prepare a winding jig in particular, and the coil-shaped wiring can be easily arranged.

(Embodiment 2)
FIG. 5 is a configuration diagram of the rice cooker according to the embodiment of the present invention. This embodiment differs from the first embodiment in that the second magnetic body 17 is disposed between the inner frame 16 and the wiring 12 in a coil shape, and the second magnetic body 17 is fixed to the inner frame 16. It is a point that has been.

  About the rice cooker comprised as mentioned above, the operation | movement and an effect | action are demonstrated below. When the low frequency magnetic field generated from the coiled wiring 12 cancels the low frequency magnetic field from the heating coil 1 and passes through the first magnetic body 13 such as ferrite, the magnetic permeability of the first magnetic body 13 is The magnetic performance changes and the distribution of the magnetic field applied to the pan 15 changes. As a result, the conventional magnetic field distribution collapses. As a result, the temperature distribution of the pan 15 that generates heat upon receiving the magnetic field from the heating coil 1 changes slightly, and the rice cooking performance deteriorates. Therefore, by disposing the second magnetic body 17 on the inner frame 16 in the vicinity of the coiled wiring 12, the magnetic field generated from the coiled wiring 12 passes through the second magnetic body 17, and the first magnetic body 17 passes through the first magnetic body 17. As a result, the magnetic field distribution of the conventional rice cooker does not change, and the influence of the coiled wiring 12 on the rice cooking performance can be prevented. Moreover, since the influence by the 2nd magnetic body 17 stays in the vicinity of the coil-shaped wiring 12, the magnetic-shielding effect with respect to the heating coil 1 of the coil-shaped wiring 12 does not deteriorate. Further, by fixing the second magnetic body 17 to the inner frame 16, the position of the second magnetic body can be determined with high accuracy. Accordingly, it is possible to suppress a change in the magnetic performance of the first magnetic body 13 by arranging the second magnetic body 17 so as to be located above the first magnetic body 13 in particular.

  Further, as shown in FIG. 6, a bent portion 19 is provided in the second magnetic body 17, and the coil-shaped wiring 12 is arranged on the first magnetic body 13 on the upper portion of the bent portion 19. 12 is fixed by the second magnetic body 17, so that positioning can be performed correctly, and the second magnetic body 17 is also disposed below the coiled wiring 12, so that a magnetic field generated from the coiled wiring 12 is generated. Radiation to the first magnetic body 13 can be further suppressed, and rice cooking performance deterioration due to a change in the magnetic performance of the first magnetic body 13 can be prevented. Here, examples of the shape of the second magnetic body 17 include an L-shaped configuration and a V-shaped configuration.

  Further, as shown in FIG. 7, a plurality of bent portions 19 are provided in the second magnetic body 17, and the coil-shaped wiring 12 is sandwiched between the second magnetic bodies 17, so that the coil-shaped wiring 12. Many of the magnetic fields generated from the second magnetic body 17 can pass through the second magnetic body 17, and radiation to the first magnetic body 13 can be further reduced. Here, the shape of the second magnetic body 17 includes a U-shaped configuration.

  As described above, in the present embodiment, the second magnetic body 17 is disposed above the first magnetic body 13 in the vicinity of the coil-shaped wiring 12, and further, the second magnetic body 17 is disposed on the outer periphery of the inner frame. Can be prevented from radiating the magnetic field generated from the coiled wiring 12 to the first magnetic body 13, and the rice cooked by the change in the magnetic performance of the first magnetic body 13 can be suppressed. The performance deterioration can be prevented and the positioning of the second magnetic body 17 can be performed with high accuracy.

(Embodiment 3)
FIG. 8 is a configuration diagram of the rice cooker according to the embodiment of the present invention. This embodiment differs from the first embodiment in that the second magnetic body 17 is disposed between the inner frame 16 and the coil-shaped wiring 12 disposed on the outer surface of the inner frame 16, and the coil-shaped wiring. In other words, the third magnetic body 18 is disposed on the opposite surface of the second magnetic body 17 with 12 interposed therebetween.

  About the rice cooker comprised as mentioned above, the operation | movement and an effect | action are demonstrated below. When the low frequency magnetic field generated from the coiled wiring 12 cancels the low frequency magnetic field from the heating coil 1 and passes through the first magnetic body 13 such as ferrite, the magnetic permeability of the first magnetic body 13 is The magnetic performance changes and the distribution of the magnetic field applied to the pan 15 changes. As a result, the conventional magnetic field distribution collapses. As a result, the temperature distribution of the pan 15 that generates heat upon receiving the magnetic field from the heating coil 1 changes slightly, and the rice cooking performance deteriorates. Therefore, by arranging a magnetic body in the vicinity of the coiled wiring 12 and arranging the magnetic field generated from the coiled wiring 12 to pass through the magnetic body, the magnetic field radiated to the first magnetic body 13 can be reduced. Can be reduced. On the other hand, as the shape of the magnetic body, by disposing the coil-like wiring 12 so as to surround the magnetic body, more magnetic field flows in the magnetic body, so that the influence on the first magnetic body 13 can be reduced. However, it is generally difficult to bend many magnetic materials. Therefore, by arranging the second magnetic body 17 and the third magnetic body 18 at positions facing each other with the coil-shaped wiring 12 interposed therebetween, it is possible to draw a loop magnetically. In addition, since the second magnetic body 17 and the third magnetic body 18 are constituted by flat plates, a magnetic body can be easily created without the need for bending work or the like.

  As described above, in the present embodiment, the third magnetic body 18 is disposed on the outer peripheral portion of the coil-shaped wiring 12 so as to face the second magnetic body 17 disposed on the outer periphery of the inner frame 16. By adopting the configuration, the magnetic field generated from the coiled wiring 12 is radiated to the first magnetic body 13 while the second magnetic body 17 and the third magnetic body 18 remain in a plate shape. It can suppress and can prevent the rice cooking performance deterioration by the change of the magnetic performance of the 1st magnetic body 12. FIG.

  The present invention is a technique that can be applied to induction heating rice cookers used for home use and business use.

The figure which shows the structure of the rice cooker in Embodiment 1 of this invention. The figure which shows the structure of the inner frame of the rice cooker in Embodiment 1 of this invention. The figure which shows the operation | movement waveform of the rice cooker in Embodiment 1 of this invention. The figure which shows the structure of another inner frame of the rice cooker in Embodiment 1 of this invention. The figure which shows the structure of the inner frame of the rice cooker in Embodiment 2 of this invention. The figure which shows the structure of another inner frame of the rice cooker in Embodiment 2 of this invention. The figure which shows the structure of another inner frame of the rice cooker in Embodiment 2 of this invention. The figure which shows the structure of the rice cooker in Embodiment 3 of this invention. The figure which shows the structure of the conventional induction heating apparatus The figure which shows the structure of the conventional induction heating apparatus The figure which shows the circuit structure of the conventional induction heating heating apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating coil 2 Electromagnetic shield ring 3 Power supply part 4 Rectification means 5 Inductor 6 Smoothing capacitor 7 Resonance capacitor 8 Semiconductor switch 11 Inverter 12 Coiled wiring 13 1st magnetic body 14 Coil frame 15 Pan 16 Inner frame 17 2nd magnetism Body 18 Third magnetic body 19 Bent part

Claims (6)

A pan, a heating coil for induction heating the pan, a coil frame for installing the heating coil, an inner frame for supporting the side of the pan at the top of the coil frame, and the pan near the back of the heating coil A plurality of first magnetic bodies arranged opposite to each other, an inverter for supplying a high-frequency current including a commercial frequency component to the heating coil, and a current component having the same frequency as the commercial frequency component flowing in the heating coil A rice cooker provided with a coil-shaped wiring disposed in a coil shape in the vicinity of the heating coil so that current flows in a direction opposite to the heating coil, and the coil-shaped wiring is disposed on the outer peripheral portion of the inner frame . The rice cooker according to claim 1, wherein a convex portion is provided on an outer peripheral portion of the inner frame, and a coil-shaped wiring is arranged in a column above the convex portion. The rice cooker according to claim 1 or 2, wherein a second magnetic body is provided above the first magnetic body in the vicinity of the coiled wiring, and the second magnetic body is fixed to an outer peripheral portion of an inner frame. The rice cooker according to claim 3, wherein a bent portion is provided in the second magnetic body, and a coiled wiring is disposed above the bent portion of the second magnetic body. The rice cooker according to claim 3, wherein a plurality of bent portions are provided in the second magnetic body, and a coiled wiring is sandwiched between the second magnetic bodies. The rice cooker according to claim 3, wherein a third magnetic body is disposed on the outer peripheral side of the coiled wiring so as to face the second magnetic body.

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