JP2012245299A - Rice cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the electric power for induction heating causes a slight gap in some cases by deviation of circuit constants and deviation among machine bodies and causes the deviation of the heating electric power to makes a factor of deviation in cooking performances.SOLUTION: By being provided with a reference means 20 making a trigger means 11 output a reference value Ton1, a computing means 21 for computing a difference between the reference value Iin1 and the value Iin of electric current detected by an electric current detection means 12 when the reference means 20 makes the trigger means 11 output the reference value Ton1, and a correction means 22 for making the value computed by the computing means a correction value and thereafter reducing the correction value from the value detected by the electric current detection means and using the value as the electric current value during cooking, when the reference value is Ton1, the rice cooker can measure a difference between the electric current value Iin detected by the electric current detection means and the reference value Iin1 and reduce deviation of source electric current by correcting the difference.

Description

  The present invention relates to a rice cooker.

  Recent rice cookers perform cooking by heating with electric power determined by providing current detection means and performing control so that the current detection means has a certain reference current value.

  FIG. 7 is a block diagram of a conventional rice cooker. In FIG. 7, the outer coil 1 and the inner coil 2 inductively heat the inner pot 3. The diode bridge 4 rectifies the alternating current supplied by the commercial power supply 5 and supplies a unidirectional power supply. Based on a unidirectional power source supplied by the diode bridge 4, the inverter circuit 9 including the smoothing capacitor 6, the resonance capacitor 7, and the switching element 8 generates high frequency power for induction heating the inner pot 3 by the outer coil 1 and the inner coil 2. generate.

  The timer means 10 outputs a pulse having a width of the set time Ton, and makes the switching element 8 conductive for the set time Ton. FIG. 8 shows a waveform diagram of each part of the switching element 8 during induction heating in the rice cooker.

  The trigger means 11 detects the collector-emitter voltage Vce (the voltage of the outer coil 1 and the inner coil 2) of the switching element 8, and as shown in the graph of FIG. 8, the switching means 8 is turned on at the moment when Vce becomes zero. The timer unit 10 is turned on to start measuring the set time Ton of the timer means 10.

  The trigger means 11 significantly reduces the loss during switching of the switching element 8 by turning on the switching element 8 at the moment when Vce becomes zero. Further, the power supply current can be controlled by increasing or decreasing the pulse width Ton of the gate voltage for turning on the switching element 8 by the timer means 10.

  The current detection means 12 detects the power supply current. The electric power for heating the inner pot 3 is controlled by controlling the current value of the current detection means 12. When the detection current is larger than the predetermined current value based on the output from the current detection means 12, the Ton setting means 13 decreases the power supply current by decreasing Ton, and conversely, the detection current is smaller than the predetermined current value. In this case, the value of Ton is determined such that Ton is increased to increase the power supply current, and the value is output to the timer means 10 so that the control is performed so as to obtain a predetermined power supply current. Note that the above-described predetermined current value is changed depending on the case of the power supply frequencies of 60 Hz and 50 Hz to cope with the influence of the power supply frequency.

Japanese Patent No. 4023438

  However, in the conventional configuration, even if the operation is performed at the same set time Ton, the induction heating power varies slightly from machine to machine due to variations in circuit constants and between aircrafts. There was a problem that the difference in power has contributed to variations in cooking performance.

  This invention solves the said conventional subject, and it aims at obtaining the rice cooker which can absorb the dispersion | variation in a circuit constant and the dispersion | variation between machine bodies, and the shift | offset | difference of heating power is small.

  In order to solve the conventional problems, the rice cooker according to the present invention includes a reference unit that causes the trigger unit to output the reference value Ton1 at the start of cooking, and the current when the reference unit outputs the reference value Ton1 to the trigger unit. A calculating means for calculating a difference between the current value Iin detected by the detecting means and the reference value Iin1, and a value calculated by the calculating means as a correction value, and thereafter, during cooking, only the correction value is obtained from the value detected by the current detecting means. By subtracting and providing correction means for using it as a current value, variations in circuit constants and variations in the body can be corrected.

  The rice cooker of the present invention can reduce variations in heating power due to the influence of circuit constant variations and machine-to-machine variations, and can reduce variations in cooking performance.

The block diagram of the rice cooker in Embodiment 1 of this invention. Sectional drawing of the rice cooker in Embodiment 1 of this invention. Block diagram of rice cooker in Embodiment 2 of the present invention Block diagram of rice cooker in Embodiment 3 of the present invention Block diagram of rice cooker in embodiment 4 of the present invention Block diagram of rice cooker in Embodiment 5 of the present invention Block diagram of a conventional rice cooker Waveform diagram of each part of switching element during induction heating in rice cooker

  1st invention is the main body which the upper surface opened, the cover part which closes an upper surface of a main body, the inner pot which detachably accommodates in the said main body and cooks and cooks, and the heating which carries out induction heating of the said inner pot A coil, a unidirectional power source obtained by rectifying the commercial power source, a switching element, a resonant capacitor, and a smoothing circuit. The inverter circuit that converts the unidirectional power source into high-frequency power and a current supplied from the commercial power source are measured. Current detecting means, timer means for turning on the switching element for a set time Ton, trigger means for monitoring the coil voltage and starting timing of the set time Ton, and the value of the current detecting means to a certain value And a Ton setting means for determining the value of Ton output from the timer means, and a reference means for causing the trigger means to output a reference value Ton1 at the start of cooking , Calculating means for calculating a difference between the current value Iin detected by the current detecting means and the reference value Iin1 when the reference means outputs the reference value Ton1 to the trigger means, and correcting the value calculated by the calculating means As a value, during cooking, the current detection means subtracts the correction value from the value detected by the current detection means and uses it as a current value, and the current detection means detects when the reference value Ton1. By measuring a deviation between the current value Iin and the reference value Iin1 and correcting the deviation as a variation, it is possible to reduce the variation in the power supply current.

  In particular, the second invention is the one obtained by adding a re-correction means that causes the reference means to output a reference value several times during cooking and causes the calculation means and the correction means to make corrections during cooking. By performing the correction a plurality of times during cooking, it is possible to cope with an increase in variation due to an increase in the body temperature due to heating.

The third invention is particularly abnormal when the difference between the current value Iin detected by the current detection means calculated by the calculation means in the first or second invention and a reference value Iin1 exceeds a certain value. Therefore, it is possible to limit the operation in the abnormal state by detecting the abnormal state of the airframe, and to improve the safety.

  4th invention adds the correction change means which can change the value of a reference value into arbitrary values with the input means and the said input means especially in any one of 1st-3rd invention. It is possible to easily change the heating power when the performance confirmation or the predetermined cooking performance does not occur.

  5th invention adds the correction value display means which displays the correction value which the said calculation means calculated to any one invention of 1st-4th, and correction value is used for the performance confirmation at the time of body design, etc. Can be used to check whether the product is as designed, etc., making it easier to check performance and improving product quality.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram of a rice cooker in Embodiment 1 of the present invention. In FIG. 1, an outer coil 1 that is a heating coil and an inner coil 2 that is a heating coil inductively heat an inner pot 3. The diode bridge 4 rectifies the alternating current supplied by the commercial power supply 5 and supplies a unidirectional power supply. An inverter circuit 9 including a smoothing circuit for smoothing by a smoothing capacitor 6 based on a unidirectional power source supplied by the diode bridge 4, a resonance capacitor 7, and a switching element 8 is formed by an inner coil 3 and an inner coil 2. To generate high frequency power for induction heating. The timer means 10 outputs a pulse having a width of the set time Ton, and makes the switching element 8 conductive for the set time Ton.

  FIG. 8 shows a waveform diagram of each part of the switching element 8 during induction heating in the rice cooker, and the trigger means 11 detects the collector-emitter voltage Vce of the switching element 8 (the voltages of the outer coil 1 and the inner coil 2). As shown in the graph of FIG. 8, the switching element 8 is turned on at the moment when Vce becomes zero, and the timing of the set time Ton of the timer means 10 is started.

  The trigger means 11 significantly reduces the loss during switching of the switching element 8 by turning on the switching element 8 at the moment when Vce becomes zero. The power supply current can be controlled by increasing or decreasing the pulse width Ton of the gate voltage at which the timer means 10 turns on the switching element 8.

  The current detection means 12 detects the power supply current. The electric power for heating the inner pot 3 is controlled by controlling the current value of the current detection means 12. When the Ton setting means 13 for determining Ton is larger than a predetermined current value based on the output from the current detecting means 12, Ton is decreased to reduce the power source current, and conversely, the detected current is predetermined. When the current value is smaller than the current value, the Ton value is determined so as to increase the power supply current, and the timer means 10 outputs the value to control the power supply current to a predetermined value. Yes.

  When cooking is started, the reference means 20 performs induction heating for a short time, for example, about 1 second, and at that time, the Ton setting means 13 performs control with the reference value Ton1. Ton1 should be set so that the detection current value of the current detection unit 12 becomes Iin1 when the timer unit 10 outputs Ton1, but actually, the detection current of the current detection unit 12 due to a constant variation, an aircraft variation, or the like. The value deviates from Iin1.

The calculation means 21 calculates DIin = Iin1-Iin using the current value Iin detected by the current detection means and the reference current value Iin1. In subsequent heating control,
Using the above-described DIin as a correction value, the correction unit 22 causes the Ton setting unit 13 to perform control so as to obtain a value obtained by subtracting the correction value DIin from the detection current value of the current detection unit 12. Thereby, the influence of various variations in heating power can be reduced.

  FIG. 2 is a cross-sectional view of the rice cooker according to Embodiment 1 of the present invention. In FIG. 2, the inner pot 3 is housed inside the main body 23. An outer coil 1 and an inner coil 2 are provided on the protective frame 24 in such a manner as to follow the bottom of the inner pot 3. A lid portion 25 is provided so as to close the upper portion of the main body 23. A substrate 26 is installed on the upper surface of the lid 25, and performs various controls of induction heating.

(Embodiment 2)
FIG. 3 is a block diagram of a rice cooker in Embodiment 2 of the present invention. In FIG. 3, re-correction means 30 is added to the first embodiment of the present invention. During cooking, the temperature of the machine body rises by heating the food, so the degree of variation changes due to the constant change due to the temperature characteristics of the circuit elements, and the correction by the correction means 22 is not an appropriate correction. As a result, the heating power is shifted.

  In order to prevent such a phenomenon, the recorrection means 30 causes the reference means 20 to output the reference value Ton1 several times during cooking, and causes the calculation means 21 and the correction means 22 to correct the temperature of the machine body. This is to prevent the deviation of the heating power from being affected by changes in various circuit element characteristics due to the increase.

(Embodiment 3)
FIG. 4 is a block diagram of a rice cooker according to Embodiment 3 of the present invention. In FIG. 4, the abnormal means 40 is added to Embodiment 1 of this invention. When the difference DIin between the current value Iin detected by the current detection means 12 calculated by the calculation means 21 and the reference value Iin1 exceeds a certain value, it is considered that abnormal heating has occurred due to a failure of a circuit element. For this reason, the abnormality means 40 performs abnormality processing such as determining that there is an abnormality, stopping heating, and performing abnormality display.

(Embodiment 4)
FIG. 5 is a block diagram of a rice cooker according to Embodiment 4 of the present invention. In FIG. 5, the input changing unit 51 and the correction changing unit 51 that can change the reference value Iin1 of the reference unit 20 to an arbitrary value are added to the first embodiment of the present invention. The heating power can be easily changed by changing the value of the reference value Iin1.

  This makes it possible to cope with performance confirmation by changing the heating power at the time of airframe design to various values and responding by changing the heating power when the predetermined cooking performance does not appear in the market It is.

(Embodiment 5)
FIG. 6 is a block diagram of a rice cooker according to Embodiment 5 of the present invention. In FIG. 6, correction value display means 60 for displaying correction value Iin calculated by calculation means 21 is added to Embodiment 1 of the present invention. It is what you did.

  By displaying the correction value Iin on the correction value display means 60 using the test mode, it can be used for confirming whether the correction value is in accordance with the design, etc. for performance confirmation at the time of airframe design. Confirmation is easy and product quality can be improved.

  As mentioned above, the rice cooker concerning this invention can reduce the variation of the heating electric power by the influence of the variation of a circuit constant and the variation between bodies, and is useful as a rice cooker with a small variation in cooking performance.

DESCRIPTION OF SYMBOLS 1 Outer coil 2 Inner coil 3 Inner pan 4 Diode bridge 5 Commercial power supply 6 Smoothing capacitor 7 Resonance capacitor 8 Switching element 9 Inverter circuit 10 Timer means 11 Trigger means 12 Current detection means 13 Ton setting means 20 Reference means 21 Calculation means 22 Correction means 23 Main body 24 Protective frame 25 Lid portion 26 Substrate 30 Re-correction means 40 Abnormal means 50 Input means 51 Correction change means 60 Correction value display means

Claims (5)

A main body having an upper surface opened, a lid portion that closes the upper surface of the main body, an inner pan that is detachably housed in the main body to cook and cook, a heating coil that induction-heats the inner pan, and a commercial power source A unidirectional power source obtained by rectification, a switching element, a resonant capacitor, a smoothing circuit, an inverter circuit that converts the unidirectional power source into high-frequency power, a current detection unit that measures a current supplied from a commercial power source, Timer means for conducting the switching element for a set time Ton, trigger means for monitoring a coil voltage and starting timing of the set time Ton, and the timer means so that the value of the current detecting means becomes a certain value. Ton setting means for determining the value of Ton to be output, reference means for causing the trigger means to output a reference value Ton1 at the start of cooking, and the reference hand Calculates the difference between the current value Iin detected by the current detection means and the reference value Iin1 when the reference value Ton1 is output to the trigger means, and the cooking is performed using the value calculated by the calculation means as a correction value. A rice cooker composed of correction means that subtracts the correction value from the value detected by the current detection means and uses it as a current value. The rice cooker according to claim 1, further comprising a re-correction unit that causes the reference unit to output a reference value several times during cooking and causes the calculation unit and the correction unit to perform correction. 3. The abnormality means according to claim 1, further comprising an abnormality means for judging that an abnormality occurs when a difference between a current value Iin detected by the current detection means calculated by the calculation means and a reference value Iin1 exceeds a certain value. rice cooker. The rice cooker of any one of Claims 1-3 which added the correction change means which can change the value of a reference value into arbitrary values with the input means and the said input means. The rice cooker of any one of Claims 1-4 which added the correction value display means to display the correction value which the said calculation means calculated.