JP6071810B2 - rice cooker - Google Patents

Description

  The present invention relates to a rice cooker used mainly at home, and more particularly to a rice cooker having induction heating means and radiation heating means.

  Conventionally, a heating coil that constitutes an induction heating means for mainly performing rice cooking is provided at the bottom of the inner pot, and a radiant heating means for assisting in performing rice cooking or preventing condensation is provided on the side surface of the inner pot. A rice cooker that has a lid is known (see, for example, Patent Document 1).

JP-A-7-289430 (2nd page, 3rd page, FIG. 2)

  The induction heating means is controlled so as to vary the energization rate according to the voltage fluctuation and maintain a constant output even if the voltage of the commercial power source fluctuates. Unlike the IH cooking heater, where an unspecified number of pans are heated, the rice cooker always maintains the same output because the relationship between the specific inner pot and the heating coil constituting the induction heating means is always the same. Control is relatively easy.

However, when the voltage of the commercial power supply fluctuates, the radiation heating means is affected by the influence and the output voltage fluctuates. Therefore, in the conventional rice cooker, in order to control the output voltage of the radiant heating means according to the voltage fluctuation of the commercial power supply, the voltage of the smoothing capacitor is divided by the resistance and then output to the control means, and based on the signal The heater energization rate is controlled.

In such a configuration, the capacitance value of the smoothing capacitor is often around 10 μF, and when the output of the high-frequency power supply is off, the voltage of the smoothing capacitor is a DC voltage and the voltage value is almost the peak voltage of the commercial power supply. However, when the output of the high-frequency power supply is on, the voltage of the smoothing capacitor is a voltage obtained by full-wave rectifying the AC voltage of the commercial power supply with a rectifier.

That is, after the voltage of the smoothing capacitor is divided by the resistor, the voltage output to the control means is a DC voltage obtained by dividing the peak voltage of the commercial power supply by the resistor when the high frequency power supply is off. When is on, the voltage value has a somewhat ripple component, and its peak value is lower than when the high frequency power supply is off.

Therefore, even if the voltage value of the commercial power supply is the same, the control means detects a different voltage value depending on the presence or absence of the output of the high frequency power supply. Therefore, a new configuration for detecting the commercial power supply voltage input from the input side of the rectifier Means had to be provided, and there was a problem that the circuit had a complicated and expensive configuration.

  In order to solve such a problem, an object of the present invention is to provide a rice cooker that does not have a complicated circuit configuration and is inexpensive and that can accurately calculate a power supply voltage at the time of output of a high-frequency power supply.

  A rice cooker according to the present invention that solves the problem includes a main body, an inner pot that is housed in the main body so as to be freely inserted and removed, a lid that is rotatably provided in the main body, and covers the upper portion of the inner pot, and is provided in the main body. An induction heating means for heating the inner pot, a radiant heating means provided in the main body and / or the lid, a switching element constituting an inverter circuit for supplying power to the induction heating means, and a switching element And a control means having a microcomputer for controlling the radiation detection means, the radiation heating means, the switching element and the frequency detection means, and the control means includes a switching element detected by the frequency detection means. The power supply voltage is calculated from the drive frequency, and the power supply rate of the radiant heating means is controlled so that the output of the radiant heating means becomes constant according to the calculated power supply voltage. One in which the.

  According to the present invention, since the drive frequency of the switching element is detected and the power supply voltage is calculated from the detected drive frequency, the output of the radiant heating means is controlled without providing a dedicated power supply voltage detection circuit. Since the power supply voltage can be obtained, the influence of the voltage fluctuation of the commercial power supply can be suppressed with an inexpensive circuit configuration, and the energization rate of the radiant heating means can be controlled, so that the output of the radiant heating means can be controlled to be constant.

It is a perspective view which shows schematic structure of the rice cooker which concerns on Embodiment 1 of this invention. It is a perspective view of the state which opened the cover which shows schematic structure of the rice cooker which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the internal structure of the rice cooker which concerns on Embodiment 1 of this invention. It is a circuit diagram which shows schematic structure of the rice cooker which concerns on Embodiment 1 of this invention. It is a graph which shows the relationship between the drive frequency and power supply voltage of the rice cooker which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the electricity supply rate control of the radiation type heating means of the rice cooker which concerns on Embodiment 1 of this invention.

Embodiment 1 FIG.
(Overall configuration)
1 is a perspective view showing a schematic configuration of a rice cooker according to Embodiment 1 of the present invention, and FIG. 2 is a perspective view of a state in which a lid is opened showing the schematic configuration of the rice cooker according to Embodiment 1 of the present invention. FIG. 3 is a cross-sectional view showing the internal configuration of the rice cooker according to Embodiment 1 of the present invention. A schematic overall configuration of the rice cooker according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 3.

  As shown in FIG. 1, reference numeral 100 denotes a rice cooker according to Embodiment 1 of the present invention, which includes a main body 1 and a lid 2. The main body 1 and the lid body 2 are each made of a resin material according to the application, and are formed by resin molding, for example. However, the body 1 and the lid body 2 are not necessarily limited to the resin material. May be used.

  As shown in FIG. 1, the lid 2 has a lid upper surface cover 2 a, and an upper lid upper surface cover 2 a near the front of the lid 2 is connected to a lid 2 described later below the lid upper surface cover 2 a. A transparent display window 4 is provided in the substrate chamber 2d, which is an internal space, so that the display contents of the display panel 15 for displaying operation results and operation status can be visually recognized.

In order to operate the rice cooker 100, an operation unit 3 having various operation buttons (not shown in detail) provided with functions such as heat retention and reservation is provided around the display window 4. Therefore, the user can operate while viewing the display content of the display panel 15.

The display panel 15 is mounted on the operation board 16 together with a switch (not shown) that receives operation inputs from the various operation buttons described above. Further, a microcomputer (not shown) and a memory (not shown) are mounted on the operation board 16. The memory stores a control program for operating the microcomputer in response to an operation by the operation button of the operation unit 3 described above.

In the first embodiment of the present invention, the configuration in which the operation unit 3 is provided on the lid has been described as an example. Can do.

Further, an exhaust port 2b for discharging steam generated during rice cooking is provided near the rear of the lid 2. In addition, although Embodiment 1 of the present invention describes a rice cooker of a type that discharges steam outside the main body, a rice cooker of a type that does not discharge steam outside the main body may be used, in which case the steam outlet is It is not provided.

  As shown in FIG. 2, a locking portion 5 a is provided in front of the upper surface of the main body, and an engaging portion (not shown) provided on the lid body 2 is engaged with the locking portion 5 a, so that the lid body 2 is connected to the main body 1. The top surface of is closed. The lid 2 is pivotally supported at the rear end thereof on a pivot shaft 8a shown in FIG.

The lid 2 is disengaged from the engaging portion (not shown) and the engaging portion 5a by pushing a locking release button 5 provided in front of the main body 1, and is opened around the rotation shaft 8a. By a biasing means (not shown) that applies a biasing force in the direction to the lid body 2, it is rotated and released to a predetermined position.

  As shown in FIG. 2, it has an opening part in the center part of a main body, and the inner pot 6 which accommodates the water and rice which are to-be-cooked rice is accommodated detachably. An inner lid 7 is provided on the surface of the lid 2 facing the inner hook 6, and the flange 6 a provided on the upper peripheral edge of the inner hook 6 and the inner lid 7 are closed as shown in FIG. 3. A seal packing 7a provided on the outer periphery of the lid 7 is contacted and sealed over the entire periphery.

The inner lid 7 is detachably mounted with a cartridge 7b provided to return the umami component generated during cooking from the cooked rice in the inner pot 6 to the inner pot 6. The cartridge 7b is also provided with a communication port 2c for discharging steam generated during cooking from the cooked rice in the inner pot 6 to the outside. The communication port 2c communicates with the exhaust port 2b.

Further, the inner lid 7 is provided with a lid heater 7c which is a radiant heating means. The lid heater 7c is energized during rice cooking and heat retention, and is used for temperature adjustment of rice cooking and heat retention, and prevention of condensation during heat retention.

  As shown in FIG. 3, induction heating coils 10 a, 10 b, and 10 c (hereinafter collectively referred to as induction heating coils 10) that are induction heating means for heating the inner pot 6 and cooking the stored rice in the main body 1. In some cases).

  A body heater 13 as a radiant heating means is provided so as to surround the body portion of the inner hook 6. The body heater 13 is energized during rice cooking and heat retention, and is used for temperature adjustment of rice cooking and heat insulation.

  Inside the heating coil 10a, a temperature sensor 11 is provided so as to be in contact with the outer central portion of the inner pot 6. The temperature sensor 11 detects the temperature of the inner pot 6 during rice cooking and is used for rice cooking control.

  A control board 9 is provided in a space on the rear (rear) side of the main body 1. On the control board 9, a power supply circuit (not shown) and an inverter circuit for supplying a high-frequency current to the induction heating coils 10a, 10b and 10c based on the control of the microcomputer mounted on the operation board 16 are mounted.

  A bottom plate 22 made of a resin material and formed by resin molding is provided at the lower portion of the rice cooker 100, and a cooling fan 12 for cooling the control board 9 and the induction heating coils 10a, 10b, and 10c is attached. Yes. The bottom plate 22 is provided with a winding type power cord (not shown).

The cooling fan 12 is disposed below the control board 9, operates when rice cooking is started, and sucks outside air from an intake hole (not shown) provided in the bottom plate 22, and the control board 9 and the induction heating coils 10a, 10b, 10c. Blow and cool down.

(Circuit configuration)
FIG. 4 is a circuit diagram showing a schematic configuration of the rice cooker according to Embodiment 1 of the present invention. The circuit configuration of the rice cooker according to Embodiment 1 of the present invention will be described with reference to FIG.

  In FIG. 4, 30 is a commercial power supply for supplying electric power to the rice cooker 100, and it is common that it is AC 100V in a domestic rice cooker. A rectifier circuit 31 is a circuit for converting AC power into DC power to obtain a DC power source, and is composed of a rectifier element such as a diode.

  32 is a choke coil, 33 is a smoothing capacitor, and they constitute a smoothing circuit. The DC power converted by the rectifier circuit 31 includes a pulsating flow called ripple, and the smoothing circuit is a circuit for flattening the pulsating flow and stabilizing the DC power.

  10 is an induction heating coil, 34 is a resonance capacitor, and they constitute a resonance circuit. Reference numeral 35 denotes a switching element for causing a high-frequency current to flow through the induction heating coil 10. Since the switching element 35 is configured by one in the circuit of the rice cooker according to Embodiment 1 of the present invention, it is called a monolithic resonance circuit. .

The rectifier circuit 31, the smoothing circuit including the choke coil 32 and the smoothing capacitor 33, the resonance capacitor 34, and the switching element 35 constitute a high frequency power supply 40.

  Reference numeral 36 denotes a VCE zero-cross detection circuit that detects a point at which the collector voltage (hereinafter referred to as VCE) of the switching element 35 is zero or lowered to a level close to zero, and 37 is a drive circuit that drives the switching element 35 on and off, Reference numeral 38 denotes control means for outputting a drive signal to the drive circuit 37 based on the input from the VCE zero-cross detection circuit 36.

As described above, since the rice cooker according to the first embodiment of the present invention is a one-stone resonance circuit, VCE is generated after turning off the switching element 35, and when the switching element 35 is turned on with the VCE being high, The loss, which is the product of voltage, increases and heat is generated.

Therefore, it is necessary to turn on the switching element 35 after the VCE of the switching element 35 becomes sufficiently low. Therefore, the VCE zero-cross detection circuit 36 detects a point where the VCE is zero or low to a level close to zero, and the control means 38 outputs an ON signal of the switching element 35 to the drive circuit 37 based on the detected signal. To do.

The frequency detection means 39 measures the number of times the switching element 35 is turned on and / or off during a predetermined time, and detects the frequency of the high-frequency current based on this number.

For example, the frequency counts the number of times of ON for 5 milliseconds, and when the number is 100 times, the ON period is 0.05 milliseconds, so that the period T (seconds) = 1 / frequency f (Hz ) 0.05 m (seconds) = 1 / frequency f (Hz) and frequency f (Hz) = 1 / 0.05 m (seconds) = 20 k (Hz).

  When the switching element 35 is operated at a constant driving frequency, the high-frequency current is affected by the voltage of the commercial power supply 30 or the impedance value composed of the induction heating coil 10, the resonance capacitor 34, and the inner pot 6.

In the induction heating type rice cooker which is the rice cooker according to the first embodiment of the present invention, unlike a general induction heating cooker using various pots capable of induction heating, the inner pot 6 for induction heating is Since the same one is always used, the relationship among the induction heating coil 10, the resonance capacitor 34, and the inner hook 6 is always constant and does not change.

For this reason, the voltage value of the commercial power supply 30 is dominant in the change of the high-frequency current. Moreover, although the period when VCE becomes low enough after turning off the switching element 35 changes if the shape, material, etc. of the inner pot 6 differ, it changes in the rice cooker which concerns on Embodiment 1 of this invention as mentioned above. Since there is no such thing, the off period is constant.

(Operation)
Next, the operation will be described. First, as an operation of the rice cooker, there are a rice cooking process and a heat retaining process after the rice cooking process is completed. The rice cooking process has a further subdivided process and is generally composed of four processes.

To explain these four steps in order, the preheating step for making the rice being cooked water absorb, the cooking step for boiling the water being cooked, and maintaining the boiling state to the rice Boiling maintenance process that eliminates water in inner pot 6 while water absorption and excess water are evaporated at the same time to gelatinize rice starch, and steamed cooked rice to make the state in inner pot 6 uniform It is an uneven process to finish.

In order to perform the above rice cooking process, an AC power source from the commercial power source 30 is rectified by the rectifier circuit 31, DC power is input to the switching element 35, and the switching element 35 is turned on / off, thereby causing the induction heating coil 10 to have a high frequency. An electric current is passed, and the inner pot 6 is induction heated by the magnetic field generated from the induction heating coil 10.

  In the rice cooking process or the heat retaining process described above, since the high-frequency current is controlled to be a predetermined output based on the detection result from the VCE zero-cross detection circuit 36, for example, the voltage of the commercial power supply 30 varies. If it is constant, the driving frequency is also constant.

When the voltage of the commercial power supply 30 decreases, the power input to the switching element 35 decreases, so that the time until the VCE voltage increases to a predetermined value becomes longer. That is, the ON period of the switching element 35 becomes longer and the driving frequency becomes lower.

When the voltage of the commercial power supply 30 is increased, the ON period of the switching element 35 is shortened and the drive frequency is increased. From this, as shown in FIG. 5, the relationship between the voltage value of the commercial power supply 30 and the drive frequency of the switching element 35 is generally proportional.

Therefore, by detecting the drive frequency of the switching element 35, a voltage value corresponding to the detected drive frequency can be calculated, and the power supply voltage can be set without preparing a dedicated voltage detection circuit.

  The lid heater 7c and the trunk heater 13 which are radiant heating means are output at a rated output, for example, 30W. The operating voltage range of the rice cooker is, for example, AC 100V ± 10%. That is, the range of AC 90V to 110V.

If the output of the lid heater 7c and the trunk heater 13 is 100V at 100V, and the output of the operating voltage is reflected in the output of the lid heater 7c and the trunk heater 13 as it is, it becomes 27W at 90V and 110V. By increasing the difference in output by 33 W, the temperature adjustment of rice cooking and heat retention, and the performance of preventing condensation during heat retention are affected.

Therefore, it is necessary to secure an operating voltage range of 100V ± 10%. The lid heater 7c and the trunk heater 13 are applied with an applied voltage (power supply voltage) of 100V so that a rated output of 30W can be output by the conduction rate control at 90V or 110V. This is a heater that outputs 33 W when energized at 100%.

  When the power supply voltage is set, the energization rate control according to the power supply voltage is performed as shown in FIG. For example, if the applied voltage (power supply voltage) is 90 V, the control is performed at a power supply rate of 100% in order to obtain an output of 30 W. Similarly, if the applied voltage (power supply voltage) is 100V, the energization rate is 90% to obtain an output of 30W, and if the applied voltage (power supply voltage) is 110V, the energization rate is 80% to obtain an output of 30W. Take control.

  In this way, the power supply voltage is calculated from the detected drive frequency, and the power supply rate control is performed according to the calculated power supply voltage, so that the influence of the voltage fluctuation of the commercial power supply 30 is suppressed, and the output of the radiant heating means Can be controlled to be constant.

  DESCRIPTION OF SYMBOLS 1 Main body, 2 Cover body, 2a Cover top cover, 2b Exhaust port, 2c Communication port, 2d Substrate room, 3 Operation part, 3a Rice cooking button, 4 Display window, 5 Lock release button, 5a Lock part, 6 Inner pot , 6a flange, 7 inner lid, 7a seal packing, 7b cartridge, 7c lid heater, 8 hinge part, 8a rotating shaft, 9 control board, 10 induction heating coil, 10a induction heating coil, 10b induction heating coil, 10c induction heating Coil, 11 Temperature sensor, 12 Cooling fan, 13 Body heater, 15 Display panel, 16 Operation board, 22 Bottom plate, 30 Commercial power supply, 31 Rectifier circuit, 32 Choke coil, 33 Smoothing capacitor, 34 Resonance capacitor, 35 Switching element, 36 VCE zero cross detection circuit, 37 drive circuit, 38 control means, 39 frequency detection Means, 40 a high frequency power source, 100 cooker.

Claims (6)

The body,
An inner pot accommodated in the main body so as to be freely inserted and removed;
A lid provided rotatably on the main body, and covering the upper part of the inner pot;
Induction heating means provided in the main body for heating the inner pot;
Radiant heating means provided in the main body or the lid, or both,
A switching element constituting an inverter circuit for supplying power to the induction heating means;
A frequency detecting means for detecting a driving frequency of the switching element;
Control means having a microcomputer for controlling the radiation heating means, the switching element and the frequency detection means,
The control means calculates a power supply voltage from the driving frequency of the switching element detected by the frequency detection means, and the radiation type so that the output of the radiation heating means becomes constant according to the calculated power supply voltage. A rice cooker characterized by controlling the energization rate of the heating means. A rice cooking button for starting cooking on the lid or the main body is provided,
When rice cooking is started by operation of the rice cooking button,
The frequency detecting means measures the number of times the switching element is turned on and / or turned off within a predetermined time from the start of cooking rice, and detects the driving frequency of the switching element based on the number of times. Item 9. A rice cooker according to item 1. A rice cooking button for starting rice cooking is provided on either the lid or the main body,
The microcomputer has a plurality of processes for executing preset rice cooking,
When rice cooking is started by operation of the rice cooking button,
Of the plurality of steps, in the step of operating the switching element, the frequency detecting means measures the number of times the switching element is turned on and / or turned off within a predetermined time from the start of rice cooking, and the number of times. The rice cooker according to claim 1, wherein a driving frequency of the switching element is detected by the method.   In the step of operating the switching element among the plurality of steps, when the switching element is operated for the first time in the step, the frequency detection means is configured to detect the switching element within a predetermined time from the start of rice cooking. 4. The rice cooker according to claim 3, wherein the number of times of turning on, the number of times of turning off, or both are measured, and the drive frequency of the switching element is detected based on the number of times.   The power supply voltage is calculated from the driving frequency of the switching element detected by the frequency detecting means in the step of operating the switching element in the step of not operating the switching element among the plurality of steps. The rice cooker as described in any one of Claim 3 or Claim 4 to do.   The power supply voltage is calculated from the driving frequency of the switching element detected by the frequency detecting means in the step of operating the switching element immediately before the step of not operating the switching element among the plurality of steps. The rice cooker according to claim 5, wherein the rice cooker is characterized.

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