JP2010207371A - Electric rice cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the influence of oscillation noise from an electromagnetic induction heating means and secure an appropriate function of a noise counteraction component. <P>SOLUTION: The electric rice cooker includes an inner pot capable of being heated by electromagnetic induction heating, an inner case removably storing the inner pot, an outer case storing and fixing the inner case, an electromagnetic induction heating means provided at the bottom of the inner case and heating the inner pot by electromagnetic induction heating, a control board located between the outer case and the inner case and vertically extendedly provided, and the noise counteraction component provided in relation to a control circuit on the control board. The noise counteraction component is provided in a position separated as far as possible from the electromagnetic induction heating means on the side opposite to the electromagnetic induction heating means through the control board. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  This invention relates to the noise countermeasure structure of the electric rice cooker provided with the electromagnetic induction heating means.

  Recent electric rice cookers have high output, high heating efficiency, and high output control responsiveness, so they can cook delicious rice quickly, so the inner pot (rice cooker) itself is made of a metal material. In addition, as the rice cooking heating means, an electromagnetic induction heating type that employs an electromagnetic induction heating means such as a work coil that induces eddy current in the inner pot by electromagnetic induction and self-heats is increasing (for example, (See Patent Document 1).

  In addition, in an electric rice cooker that employs such an electromagnetic induction heating means, in order to make the cooked rice better, it replaces the inner pot made of the above-mentioned conventional metal material, and further non-metal such as ceramic An inner pot made of a material (so-called earthen pot) is also used (see, for example, Patent Document 2).

  In the latter case, since the inner pot itself does not generate heat due to electromagnetic induction, for example, a metal induction heating element with high electromagnetic induction efficiency is disposed on the outer peripheral surface of the inner pot, while this induction heating element is used as the work coil or the like. A heating structure that heats the inner pot by induction heating using electromagnetic induction heating means is employed (see, for example, Patent Document 3).

  And in the case of these electric rice cookers, various noise will generate | occur | produce in whichever. Among them, electromagnetic induction heating means such as a work coil is driven by a high-frequency voltage and acts as a kind of high-frequency oscillation coil. Therefore, noise noise associated with the oscillation is a problem. For example, if the noise is large, it will affect the microcomputer of the control unit, cause malfunctions, and adversely affect external devices (such as televisions and personal computers) around the rice cooker.

  For these reasons, generally, the control circuit of an electric rice cooker as described above is provided with a noise-preventing capacitor having a relatively large capacity as a noise countermeasure component, thereby absorbing noise and noise. (For example, refer to Patent Document 4).

JP 2004-201804 A Utility Model Registration No. 3110038 Japanese Patent Application No. 2006-113285 [Home Appliance Repair Technology Qualification Series] New Service Technology by Product Japan Broadcasting Publishing Association October 25, 1993 Page 89 [Figure 5-4] Electrical Circuit

  However, in the conventional electric rice cooker, the noise countermeasure component (capacitor or the like) is provided directly on a control board having a control circuit for driving and controlling the electromagnetic induction heating means. Is generally provided upright at a position as close as possible to electromagnetic induction heating means such as a work coil at the bottom of the inner case because of the wiring.

  Therefore, a problem has been found that strong oscillation noise (electromagnetic noise) from the electromagnetic induction heating means such as the work coil directly affects and does not necessarily perform an effective noise prevention function.

  In particular, the measurement frequency of the recent international standard CISPR14 requires a noise reduction function in the low frequency range of 150 kHz to 30 kHz. Compared with the frequency of 526.5 kHz to 30 kHz, noise reduction performance at a higher level is required.

  The present invention has been made to solve such a problem, and the noise induction component such as the noise prevention capacitor is connected to the electromagnetic induction heating on the side opposite to the electromagnetic induction heating means via the control board. An object of the present invention is to provide an electric rice cooker that is not affected by the oscillation noise of the electromagnetic induction heating means by being provided at a position as far as possible from the means.

  In order to achieve the same object, the present invention comprises the following problem solving means.

(1) Problem-solving means of the invention of claim 1 The problem-solving means of the present invention is an inner pot capable of electromagnetic induction heating, an inner case that accommodates the inner pot so as to be removable, and accommodates and fixes the inner case. An outer case, an electromagnetic induction heating means provided at the bottom of the inner case, for electromagnetically heating the inner pot, a control board provided between the outer case and the inner case and extending in the vertical direction; An electric rice cooker comprising a noise countermeasure component provided in association with a control circuit on a control board, wherein the noise countermeasure component is placed on the opposite side of the electromagnetic induction heating means via the control board. It is provided at a position as far as possible from the electromagnetic induction heating means.

  According to such a configuration, noise countermeasure parts such as a noise prevention capacitor are as far away as possible from the electromagnetic induction heating means, and the propagation space of electromagnetic noise from the electromagnetic induction heating means to the noise countermeasure parts is entirely on the copper foil and the like. Since it is reliably shielded and electromagnetically shielded by the control board having a high electromagnetic shielding function having a printed pattern, it is possible to effectively avoid the influence of electromagnetic noise from the electromagnetic induction heating means on the noise countermeasure component.

  Further, in such a configuration, the noise countermeasure component is isolated from the heat-generating electronic component and the inductive electronic component on the control board, and is not affected by the heat, inductive action, and floating charge.

  For this reason, noise countermeasure components such as capacitors can effectively exhibit noise absorbing action.

(2) The problem solving means of the invention of claim 2 The problem solving means of the invention is the configuration of the problem solving means of the invention of claim 1, wherein an operation board corresponding to the operation panel is held inside the outer case. An operation board cover is provided, and a noise countermeasure component is installed using a noise countermeasure component installation section provided on the lower end side of the operation board cover.

  In any electric rice cooker, there is generally a relatively wide dead space below the operation board. The dead space is also effective as a heat dissipation space.

  Therefore, using the space part with the same heat dissipation effect, and using the operation board cover holding the operation board to provide the noise countermeasure component installation part, the above noise countermeasure component is installed. Efficient use of space factor in rice cooker body and ease of installation work (can be installed at the same time when the operation board is attached to the operation board cover), performance reliability (unlike that on the board, floating electric charge of peripheral electronic components and The influence of electromagnetic waves can be avoided), and the heat dissipation effect can be achieved.

(3) The problem-solving means of the invention of claim 3 The problem-solving means of the invention is the configuration of the problem-solving means of the invention of claim 1 or 2, wherein a cooling fan for cooling electrical components is provided inside the outer case. The noise countermeasure component is provided at a position cooled by cooling air from the cooling fan.

  According to such a configuration, in addition to the heat dissipation action using the dead space, the noise countermeasure component is efficiently cooled by the cooling air from the cooling fan, and the temperature rise of the noise countermeasure component such as a capacitor is avoided. In addition, a more appropriate noise absorbing action can be ensured.

  As a result of the above, according to the present invention, it is possible to avoid the influence of electromagnetic noise from electromagnetic induction heating means such as a work coil on noise countermeasure parts such as a capacitor, and to exhibit a more reliable noise countermeasure function. Therefore, the reliability of the control function of the electric rice cooker such as a microcomputer can be ensured, and proper rice cooking performance can be maintained. Of course, it is possible to comply with international standards.

It is a cutting sectional view in the front-rear direction central portion showing the configuration of the rice cooker body of the electric rice cooker according to Embodiment 1 of the present invention. It is the horizontal sectional view seen from the bottom side of the electric rice cooker main part. It is a planar development view which shows the connection relation between electric circuit boards, such as a control board of the same electric rice cooker, and an operation board. It is a cutting sectional view in the front-rear direction central portion showing the configuration of the rice cooker body of the electric rice cooker according to Embodiment 2 of the present invention.

(Embodiment 1)
First, FIGS. 1-3 has each shown the structure and effect | action of the electric rice cooker which concerns on Embodiment 1 of this invention.

(Basic configuration)
First, the electric rice cooker according to Embodiment 1 of the present invention employs, for example, an inner pot (rice cooker) 3 made of a magnetic metal plate capable of electromagnetic induction, while the inner pot 3 is heated during rice cooking. As a means, the inner case 4 is wrapped so as to wrap substantially the entire side wall portion 3b from the bottom wall portion 3a of the inner pot 3 through an inner case 4 made of synthetic resin and provided in the outer case 1 at a predetermined interval. First and second sets of work coils C ₁ and C ₂ corresponding to the center side and the side of the bottom wall portion 3a of the pan 3 are provided, and the inner pan 3 is heated when it is kept warm. As means, a heat retaining heater H ₁ corresponding to the entire circumference of the side wall 3b of the inner pot 3 and a shoulder heater H ₂ corresponding to the entire circumference of the opening edge 3c are provided. Then, by appropriately driving and controlling them by the microcomputer control unit 40 shown in FIG. 3, an appropriate rice cooking / cooking function and a heat retaining function can be realized.

  The outer case 1 includes a cylindrical metal side wall portion 1a and a bottom wall portion 1b made of a dish-like synthetic resin fitted and integrated with a lower side of the side wall portion 1a. The rice cooker main body which is integrated with each other by being connected to the upper end side of the inner case 3 through a shoulder member made of metal is thereby formed.

  And the lid unit 2 which opens and closes in the front-back direction is provided in the opening part of the said upper part side of this rice cooker main body via the hinge part 11 provided in the shoulder rear end side.

  The lid unit 2 has an outer peripheral surface and a synthetic resin outer cover 12 provided with a pressure adjusting member 30 at a central pressure adjusting port 31 portion, and is fitted and integrated inside the outer cover 12. A synthetic resin inner cover 13 provided and a metal inner lid 19 fitted to the outer periphery of the inner cover 13 via a poly cover 14 are provided.

  On the open end (front end) side, an operation lever 18 that engages with a predetermined position of the lid unit 2 and restricts the opening and closing of the lid unit 2 in the front-rear direction is provided.

On the other hand, timer reservation for the above rice cooking / cooking / warming functions of the rice cooker, selection of rice cooking and warming menu, selection of heating cooking menu, selection of heating amount corresponding to each menu, heating pattern, warming temperature, warming time, etc. The setting operation is performed by the user via various input switch groups (operation key groups) 22a to 22h (see FIG. 3) provided on the front side operation panel unit 20 of the rice cooker body, and according to the selection setting contents Finally, the first and second work coils C ₁ and C _{2, the} heat retaining heater H ₁ and the shoulder heater H ₂ are appropriately controlled.

  In addition, in the central portion of the operation panel unit 20, rice cooking, cooking (for example, bread fermentation / baking), heat insulation menu, set heat retention temperature, set heat retention time, heat retention elapsed time, current time, timer rice reservation A liquid crystal display unit 21 is provided for displaying time, rice cooking completion, remaining time until cooking completion, and various other necessary items.

  Further, the inner portion (back space portion) of the operation panel portion 20 of the outer case 1 is configured to descend obliquely forward from the upper position on the upper side of the inner case 4 side control substrate 9a to be described later. An operation board cover 7 holding a microcomputer board 7a is installed in an inclined state in parallel with the operation panel 20.

On the other hand, a coil cover (coil base) 16 having a ferrite core storage portion 15 is provided below the bottom wall portion 4a of the inner case 4, and litz wires are concentrically wound between them. The first and second sets of work coils C ₁ and C ₂ are provided, and when the work coils C ₁ and C ₂ are energized, an eddy current is induced in the inner pot 3 to heat it. It is like that.

On the front side of the inner case 4 (and the coil cover 16) is an IGBT or heater drive that controls the driving of the first and second work coils C ₁ and C ₂ , the heat retaining heater H ₁ , the shoulder heater H _2, etc. A control board 9a provided with a circuit, a rectifier circuit composed of a diode bridge for power supply voltage rectification, a smoothing circuit, and the like, and a control board cover 9 holding the control board 9a are substantially the same height as the inner case 4, and The lateral width of the outer case 1 that extends between the left and right side walls 1a, 1a is set up vertically.

  The dish-shaped bottom wall 4a of the inner case 4 is formed with a fitting port for the center sensor S in which a thermistor is housed in the center of the bottom surface.

  In addition, an inlet 21 for cooling air having a lattice structure is formed on the front side of the bottom wall portion 1b of the rice cooker main body, and an upper portion of the inlet 21 for cooling air is used for cooling electrical components and the like. A fan (a short shaft propeller fan) 22 is provided, and cooling air from the cooling fan 22 for cooling the electrical components and the like is introduced into a necessary portion in the rice cooker body.

As shown in the figure, the electric component cooling fan 22 has an impeller portion of approximately a half of the diameter corresponding to the space on the work coils C ₁ and C ₂ side from the control board cover 9. On the other hand, the other half diameter part is installed corresponding to the heat sink 23 for heat-radiating and cooling heat-generating parts such as IGBT, the control board 9a, and the operation board cover 7 (operation board 7a). .

According to such a configuration, the wind from the impeller of the cooling fan 22 for the electrical component or the like is, on the front side of the rice cooker body, the operation board 7a, the control board 9a, the heat sink 23 for heat-generating component cooling such as the IGBT, While effectively used for cooling a noise countermeasure component 10 and the like which will be described later, it is also effectively introduced into the ventilation space of the ventilation path surrounding the first and second work coils C ₁ and C ₂ which are the heat generating members. The first and second work coils C ₁ and C ₂ are effectively cooled.

(Installation structure of noise countermeasure parts)
On the other hand, a noise countermeasure component installation portion 8 is provided at the lower end of the operation board cover 7 in the outer case 1a as shown in the figure. The noise countermeasure component cover 16 is attached via mounting edges 16a and 16b on the left and right ends, and noise countermeasure components such as a noise prevention capacitor are provided inside the corner portion of the noise countermeasure component cover 16. 10 (fitted from the back side), left and right side mounting edge portions 16a having screw holes shown in the mounting bases 8a and 8b having screw grooves on both left and right sides of the noise countermeasure component installation portion 8; By superposing 16b and fastening and fixing with a screw screw (not shown), for example, as shown in the electric circuit diagram of FIG. Away from work coil C _1, C ₂ well, and placed through the control board 9a, is connected via a first, second electrical wiring 11, 11 and the control circuit of the control board 9a side .

  In addition, the code | symbol 12 in FIG. 1 is a flat cable which connects each circuit by the side of the control board 9a and the operation board 7a.

  Further, the noise countermeasure component installation unit 8 corresponds to the impeller (air outlet) of the cooling fan 22 for electrical components etc. in the positional relationship as shown in FIGS. 1 and 2, for example, as described above. When the electric component cooling fan 22 is driven, it is efficiently cooled by the air flow blown in the direction of the heat sink 23 and the operation board 7a.

According to such a configuration, the noise countermeasure component 10 is installed farthest away from the first and second work coils C ₁ and C ₂ that generate strong high-frequency noise on the front side of the rice cooker body 1. together becomes, the first, high control board 9a and a synthetic resin having shielding function against the electromagnetic wave printed pattern is provided such as a copper foil over substantially the entire surface between the second work coil C _1, C ₂ The control board cover 9 is interposed, and the propagation space of the noise radio wave is blocked in both the vertical and horizontal directions.

  As a result, the influence of the work coil noise on the noise countermeasure component 10 side is avoided as much as possible, and the noise reduction effect of the noise countermeasure circuit is improved.

  In addition, since the cooling air from the cooling fan 22 for electrical components and the like is efficiently supplied to the noise countermeasure component installation portion 8 at the lower part of the operation board cover 7 as described above, the noise countermeasure component The cooling effect of 10 itself is also increased.

  Therefore, the noise reduction effect can be further effectively improved in this respect.

(Configuration of control circuit part)
Next, FIG. 3 shows the structure of the control circuit part which performs the rice cooking and heat retention control by the rice cooker main body side which consists of the operation board | substrate 7a comprised as mentioned above, and the control board 9a, and other control.

  First, on the operation board 7a side, with the microcomputer control unit 40 as the center, liquid crystal display unit 21, rice cooking or heat retention, timer reservation, reservation time setting, white rice or brown rice, early cooking, rice porridge, sushi, cooking, etc. Input switches 22a to 22h for selecting and setting various types of rice cooking or heat retention functions such as the normal mode, the energy saving mode, and display LEDs 23a to 23c for rice cooking, reservation, and heat retention are provided.

On the control board 9a side, the power supply circuit section includes rectifying and smoothing circuits 35a and 35b, a 20V power supply 36 via a temperature fuse 34, a constant voltage stabilizing power supply circuit 41, a power supply synchronizing circuit 43, and work coils C ₁ and C _2. IGBT 37, resonance capacitor 38, abnormal voltage detection circuit 39, IGBT drive circuit 42, and heater H ₁ and H ₂ drive circuit sections are the insulation heater drive circuit 33, shoulder heater drive circuit 34, and cooling fan 22 fan. A DC fan drive circuit 16 is provided in each of the drive circuit sections of the motor 22a. The power supply synchronization circuit 43, the IGBT drive circuit 42, the constant voltage stabilization power supply circuit 41, the fan motor drive circuit 16, the heat retaining heater drive circuit 33, The shoulder heater drive circuit 34 and the like are the above-described flat cable 12 (see FIG. 1) to the microcomputer control unit 40 on the operation board 7a side as shown in the figure.

  An AC power supply 30 is input to the power supply circuit portion of the control board 9a through a power supply board 31 provided with a noise filter circuit 32 for cutting power supply noise.

  Between the power supply lines 13 and 13 of the power supply circuit, a noise prevention capacitor Co as the above-described noise countermeasure component 10 is interposed, and the capacitor Co has a sufficient length of electricity as described above. It is housed and provided in the noise countermeasure component cover 16 of the noise countermeasure component installation portion 8 provided at the lower end portion of the operation board 7 on the operation board 7a side via the wirings 11 and 11.

  As described above, according to the present invention, an inner pot capable of electromagnetic induction heating, an inner case for detachably storing the inner pot, an outer case for accommodating and fixing the inner case, and a bottom portion of the inner case are provided. Electromagnetic induction heating means for electromagnetically heating the inner pot, a control board provided between the outer case and the inner case and extending vertically, and a control circuit provided on the control board. In the electric rice cooker comprising the noise countermeasure component, the noise countermeasure component is made as possible as possible from the work coil on the side opposite to the work coil as the electromagnetic induction heating means via the control board as described above. It is provided at a position far away.

  According to such a configuration, noise countermeasure parts such as a noise prevention capacitor are separated as far as possible from the work coil as the electromagnetic induction heating means, and electromagnetic waves from the work coil as the electromagnetic induction heating means to the noise countermeasure parts are separated. The noise propagation space is reliably shielded and electromagnetically shielded by a control board with a high electromagnetic shielding function that has a printed pattern on the entire copper foil, etc., so that the effects of electromagnetic noise on noise countermeasure parts can be effectively avoided. it can.

  Further, in such a configuration, the noise countermeasure component is isolated from the heat generating electronic component, the inductive electronic component and the like on the control board, and is not affected by the heat, inductive action, and floating charge.

  For this reason, noise countermeasure components such as capacitors can effectively exhibit noise absorbing action.

  In this case, the present invention includes an operation board cover for holding an operation board corresponding to the operation panel inside the outer case, and uses a noise countermeasure component installation portion provided on the lower end side of the operation board cover. And noise reduction parts are installed.

  In any electric rice cooker, there is generally a relatively wide dead space below the operation board. The dead space is also effective as a heat dissipation space.

  Therefore, use the space part with high heat dissipation effect, and use the operation board cover holding the operation board to provide the noise countermeasure part installation part, and install the noise countermeasure part as described above Then, effective use of the space factor in the rice cooker body and ease of installation work (can be installed at the same time when the operation board is attached to the operation board cover), performance reliability (unlike on the board, floating of surrounding electronic components) The effects of electric charges and electromagnetic waves can be avoided), and the heat dissipation effect can be achieved.

  Further, in the present invention, a cooling fan for cooling the electrical components is provided inside the outer case, and the noise countermeasure component is provided at a position cooled by the cooling air from the cooling fan.

  Therefore, in addition to the heat dissipation action using the dead space, the noise countermeasure component is efficiently cooled by the cooling air from the cooling fan, avoiding the temperature rise of the noise countermeasure component such as a capacitor, and more appropriate. Noise absorbing action can be ensured.

  As a result, according to the present invention, it is possible to avoid the influence of the electromagnetic noise from the electromagnetic induction heating means such as the work coil on the noise countermeasure component such as the capacitor and to exhibit a more reliable noise countermeasure function. Therefore, the reliability of the control function of the electric rice cooker such as a microcomputer can be ensured, and proper rice cooking performance can be maintained. Of course, it will be possible to comply with international standards.

(Embodiment 2)
Next, FIG. 4 has shown the structure of the electric rice cooker which concerns on Embodiment 2 of this invention.

  In the configuration of the first embodiment, the noise countermeasure component cover 16 having the noise countermeasure component 10 mounted on the lower surface of the noise countermeasure component installation portion 8 on the operation board cover 7 side is fastened and fixed with screws. I try to install it.

  However, for example, as shown in FIG. 4, a noise countermeasure component storage case 18 having a U-shaped cross-section with an open front surface is integrally formed at the lower end portion of the operation board cover 7, so that the operation board cover 7 and the noise The countermeasure component cover may be integrated, and the noise countermeasure component 10 may be easily accommodated from the front side opening 18a.

  With such a configuration, the installation work of the noise countermeasure component 10 becomes easier.

C ₁ and C ₂ are first and second work coils, H ₁ is a heat retaining heater, H ₂ is a shoulder heater, 1 is an outer case, 1a is a side wall, 1b is a bottom wall, 2 is a lid unit, 3 Is an operation board cover, 7a is an operation board, 8 is a noise countermeasure component installation part, 8a and 8b are attachment parts, 9 is an operation board cover, 9a is a control board, 11 and 11 are electrical wirings, 20 is An operation panel, 21 is a liquid crystal display unit, 22 is a cooling fan, 37 is an IGBT, 40 is a microcomputer control unit, and 42 is an IGBT drive circuit.

Claims (3)

  An inner pot capable of electromagnetic induction heating, an inner case for detachably storing the inner pot, an outer case for accommodating and fixing the inner case, and a bottom portion of the inner case, the inner pot being heated by electromagnetic induction heating Electromagnetic induction heating means, a control board provided between the outer case and the inner case and extending in the vertical direction, and a noise countermeasure component provided in connection with a control circuit on the control board. An electric rice cooker, wherein the noise countermeasure component is provided at a position as far as possible from the electromagnetic induction heating means opposite to the electromagnetic induction heating means via the control board. Electric rice cooker.   An operation board cover for holding an operation board corresponding to the operation panel is provided inside the outer case, and noise countermeasure parts are installed by using a noise countermeasure part installation part provided on the lower end side of the operation board cover. The electric rice cooker of Claim 1 characterized by the above-mentioned.   3. A cooling fan for cooling an electrical component is provided inside the outer case, and the noise countermeasure component is provided at a position cooled by cooling air from the cooling fan. Electric rice cooker.

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