JP5045582B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker used for general households and business use that detects and controls a current flowing through a heating coil with high accuracy.

Conventionally, in this type of induction heating cooker, the coil current flowing in the heating coil is detected, and the coil current is limited so as to be equal to or less than a predetermined value to ensure safety (for example, patents) Reference 1).
JP 2003-217815 A

  However, in the conventional configuration, since the current flowing through the heating coil differs depending on the material of the cooking container, if the value of the voltage dividing resistor for detecting the coil current is fixed, the resolution of AD conversion detected by the microcomputer is lowered. Therefore, there was a problem that the controllability deteriorated.

  The present invention solves the above-described conventional problems, and an object thereof is to provide an induction heating cooker that can detect a coil current with high accuracy regardless of the material of the cooking container and has high controllability and safety.

  In order to solve the above-described conventional problems, an induction heating cooker according to the present invention converts a coil current into a voltage with a magnitude of an amplitude of a current flowing through a heating coil, and lowers the voltage to a microcomputer (hereinafter referred to as a microcomputer). ), The voltage dividing resistor is switched in order to perform AD conversion. For example, in the case of a material such as aluminum, since the amplitude of the coil current is large, switching to the low resistance side is performed. In the case of a material such as enamel, since the amplitude of the coil current is small, the voltage input to the microcomputer is small because the voltage dividing ratio is fixed when the voltage is divided while maintaining the low resistance side. Therefore, the resolution of AD conversion of the microcomputer is lowered. Therefore, by switching from the low resistance side to the high resistance side and increasing the voltage dividing ratio on the high resistance side to the voltage dividing ratio on the low resistance side, the divided voltage becomes larger than that on the low resistance side. As a result, the voltage input to the microcomputer also increases, so that the resolution of AD conversion of the microcomputer increases.

  As a result, even when the amplitude of the coil current is different due to the difference in the material of the cooking vessel, the resolution of AD conversion for detecting the coil current of the microcomputer can be kept high by switching the voltage dividing resistor, so that the coil current can be reduced. It can be detected with high accuracy, and the controllability and safety of limiting the coil current can be improved.

  The induction heating cooker of the present invention can detect the coil current with high accuracy because the resolution of AD conversion detected by the microcomputer can be maintained even if the magnitude of the coil current varies depending on the material of the cooking container. In addition, the coil current can be limited with good control, and safety can be improved.

A first invention is a heating coil for heating a cooking vessel, a switching means for controlling a high-frequency current supplied to the heating coil, a coil current flowing through the heating coil is converted into a voltage, and the voltage is dropped by a voltage dividing resistor. A coil current detecting means for detecting the cooking container, a cooking container identifying means for identifying the cooking container placed on a top plate installed on the top of the heating coil, and the coil current flowing through the heating coil is not more than a predetermined value. Coil current limiter means for limiting the coil current, and a microcomputer that reads the output of the coil current detection means and controls the coil current limiter means and the cooking container identification means, and when heating is started, After the cooking container identification means is operated by the microcomputer, the coil current detection means is determined according to the identification result. By switching, by a the induction heating cooker as you heat the cooking container, because the resolution of AD conversion when the detection of the microcomputer even coil current changes can be kept high by the material of the cooking container The coil current can be detected with high accuracy, the coil current can be limited with high accuracy, and safety is improved.

  In the second invention, in particular, in the first invention, in the case of a material such as aluminum in which the coil current is large, the coil current as in a hollow is used so as to reduce the voltage dividing resistance and the voltage dividing ratio. In the case of a material with a small value, by switching the voltage dividing resistor so that the voltage dividing resistance is increased and the voltage dividing ratio is increased, the resolution of AD conversion can be increased and the coil current can be detected with high accuracy as in the first invention. .

  In the third invention, in particular, in the first or second invention, in the case of a material through which a coil current having an intermediate size between aluminum and enamel flows, the resolution of AD conversion is further changed by switching the voltage dividing resistor. The coil current can be detected with high precision as in the first and second inventions.

  In the fourth invention, in particular, in any one of the first to third inventions, since the switching unit has a plurality of configurations for changing the voltage dividing resistance, simultaneous switching of the voltage dividing resistance or a combination thereof, A plurality of voltage dividing resistors can be created by switching the voltage dividing resistors.

  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 shows the configuration of an induction heating cooker according to the first embodiment of the present invention.

  In FIG. 1, a heating coil 3 for heating the pan 1, a top plate 2 on which the pan 1 is placed, and a high frequency current are supplied to the heating coil 3, and the pan 1 is electromagnetically induced. The material of the pan 1 placed on the top plate 2 is identified from the inverter 4 that generates heat, the coil current detection means 5 that converts the current flowing in the heating coil 3 into a voltage and detects the voltage by dropping the voltage. The cooking container identifying means 6, the coil current limiter means 7 for limiting the coil current so that the coil current flowing through the heating coil 3 is below a predetermined value, the output of the coil current detection means 5 is read, and the coil current limiter means 7 and cooking A microcomputer 8 for controlling the container identification unit 6 is provided. The coil current detection unit 5 converts the coil current into a voltage, and then drops the voltage to a predetermined voltage according to a voltage division ratio formed by the voltage dividing resistors 1 to 3.

  About the induction heating cooking appliance comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  In the induction heating cooker, when a power switch (not shown) is turned on to start heating, in order to identify the material of the pan 1, the microcomputer 8 reads the output of the coil current detection means 5, and the cooking container identification means 6 Operates and determines material. Depending on the material of the pot 1, the voltage dividing resistance of the coil current detection means 5 is switched, and the coil current limiter means 7 and the inverter 4 are operated to heat the pot 1.

FIG. 2 shows an output in switching of the voltage dividing resistance of the coil current detection means 5 of the induction heating cooker in the first embodiment of the present invention. The amplitude of the coil current when the material of the pot 1 is aluminum, as in FIG. 2 (1) (top) is the amplitude of the coil current and I ₂ in the case of I ₁ and enamel. If I ₁ = 2I ₂ and the voltage is dropped only by the voltage dividing resistor 3 and the voltage dividing resistor 1 of the coil current detecting means 5 in FIG. 1, the voltage dividing ratio determined from the voltage dividing resistor is always fixed. , the while maintaining the relationship of FIG. 2 (2) _{V 1} and the same _V and _{V 2} also coil current obtained by converting the _{I 2} to the voltage 1 = 2V ₂ obtained by converting the _{I 1} to the voltage as in (middle). Because this is the output voltage of the coil current detection means 5, for who I ₁ when the microcomputer 8 reads the large amplitude, towards the aluminum increases the resolution of AD conversion of the microcomputer. However, since I ₂ has only half the amplitude of I ₁ , the resolution of AD conversion of the microcomputer is lower in the enamel. Therefore, when the amplitude of the coil current is large, switching is made to the low resistance side, and when the amplitude of the coil current is small, switching is made to the high resistance side. When the enamel pan 1 through which the current I ₂ flows is placed on the top plate 2, the voltage is newly reduced by the voltage dividing resistor 3 and the voltage dividing resistor 2. At this time, the voltage dividing resistor 2 is designed so that the voltage dividing ratio of the voltage dividing resistor 2 and the voltage dividing resistor 3 is twice the voltage dividing ratio of the voltage dividing resistor 1 and the voltage dividing resistor 3, so that FIG. As shown in (lower), the amplitudes of I ₁ and I ₂ are the same, and the resolution of AD conversion of the microcomputer is increased as in the case of aluminum. If a pan made of a material having a small coil current amplitude is switched to a higher resistance side, the voltage dividing ratio becomes larger than that of the lower resistance side, so that the resolution can be set higher by setting the voltage dividing resistance to an appropriate value. As a result, the accuracy of the coil current limiter means for limiting the coil current to a predetermined value or less is improved, and the safety of the induction heating cooker is also improved.

  Further, in the present embodiment, the voltage dividing resistor is switched so as to be switched between aluminum and enamel, but when the coil current having an intermediate size between aluminum and enamel flows, a new voltage dividing resistor is provided. Further, the resolution of the AD conversion of the microcomputer is further increased regardless of the material. A plurality of voltage dividing resistors may be further provided.

  Although the voltage dividing resistor 3 is fixed and the voltage dividing resistor 1 and the voltage dividing resistor 2 are switched, the voltage dividing resistor 3 side may be switched. If a plurality of voltage dividing resistors are switched simultaneously, a plurality of voltage dividing ratios by other voltage dividing resistors can be created.

  As described above, the induction heating cooker according to the present invention can maintain high resolution of AD conversion detected by the microcomputer even when the magnitude of the current flowing through the heating coil varies depending on the material and shape of the object to be heated. Therefore, since the coil current can be detected with high accuracy, it can be used for cooking appliances for home use or business use.

The block diagram of the induction heating cooking appliance in Embodiment 1 of this invention The figure of the output in switching of the partial pressure resistance of the coil electric current detection means of the induction heating cooking appliance in Embodiment 1 of this invention

Explanation of symbols

1 Pot (cooking container)
2 Top plate 3 Heating coil 4 Inverter (switching means)
5 Coil current detection means 6 Cooking container identification means 7 Coil current limiter means 8 Microcomputer (microcomputer)

Claims (4)

A heating coil for heating the cooking vessel, switching means for controlling the high-frequency current supplied to the heating coil, and a coil current for detecting the coil current flowing in the heating coil by converting it into a voltage and dropping the voltage by a voltage dividing resistor Detecting means, cooking container identifying means for identifying the cooking container placed on the top plate installed on the top of the heating coil, and the coil current so that the coil current flowing through the heating coil is less than or equal to a predetermined value. A coil current limiter means for limiting, and a microcomputer for reading the output of the coil current detection means and controlling the coil current limiter means and the cooking container identification means, and when cooking is started, the cooking by the microcomputer after container identification means is operated by the identification result, by switching the coil current sensing means Induction heating cooker as you heat the cooking container. For material coil current increases as the aluminum, so as to lower the smaller and divider ratio of the divider resistors, when the material in which the coil current is small as enamel, increasing the partial pressure resistors The induction heating cooker according to claim 1, wherein the partial pressure resistance is switched so as to increase a partial pressure ratio. The induction heating cooker according to claim 1 or 2, wherein the voltage dividing resistance is switched when a coil current having an intermediate size between aluminum and enamel flows. The induction heating cooker according to any one of claims 1 to 3, wherein the switching unit includes a plurality of configurations for changing the voltage dividing resistance.

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