JP4285355B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker that can accurately detect boiling regardless of a change in input power.

Conventionally, in an induction heating cooker, one using a thermistor to detect the temperature of a cooking vessel (for example, see Patent Document 1) and one using an infrared sensor (for example, see Patent Document 2) are known.
JP 2003-7444 A Japanese Patent Laid-Open No. 3-184295

  However, none of the conventional configurations considers the change in input power. For example, when using one heating unit of an induction heating cooker for boiling water cooking and when using the whole (multiple) heating unit for boiling water cooking, even if the same heating unit is used, its input power Is something that changes. Therefore, all the conventional configurations have a problem that boiling cannot be detected accurately if there is a change in input power.

  This invention solves the said conventional subject, and it aims at providing the induction heating cooking appliance which can detect a boiling accurately even when input electric power changes.

  In order to solve the above-described conventional problems, an induction heating cooker according to the present invention includes an infrared detector that detects infrared rays emitted from the bottom surface of a cooking vessel, and a temperature that detects the temperature of the cooking vessel from the output of the infrared detector. A detection means; a water amount determination means for determining the amount of water in the cooking container from the output of the temperature detection means; and a boiling detection means for detecting boiling from the output of the temperature detection means. The boiling detection means is determined by the water amount determination means. When the input power changes after determining the boiling detection condition based on, the boiling detection condition is changed.

  Thus, if the input power changes after the boiling detection condition is determined, the optimum boiling detection condition can be determined according to the amount of water, and the boiling detection can be performed with high accuracy.

The induction heating cooker of the present invention can determine the optimum boiling detection condition according to the amount of water if the input power changes , and can detect the boiling with high accuracy.

The first invention includes a plurality of heating unit including a plurality of heating portions or one or more of the heating coils and a heating means other than the heating coil comprising a plurality of heating coils to heat the cooking container, on top of the heating coil A top plate for holding the cooking container; infrared detection means for detecting infrared rays radiated from the bottom surface of the cooking container; and detecting the temperature of the cooking container from the output of the infrared detection means Temperature detecting means for determining the amount of water in the cooking container according to the time until the output of the temperature detecting means reaches the temperature determination value T2 from the temperature determination value T1 , with the input power being constant, and the temperature detection A predetermined time Δt determined in advance from the output of the means
Boiling detection means for detecting boiling when it is detected that the temperature difference of the cooking container detected during the period is within a predetermined temperature difference ΔT determined in advance , and the boiling detection means comprises the amount of water When the input power changes due to simultaneous heating of the plurality of heating units after determining the predetermined time Δt and the predetermined temperature difference ΔT optimum for the amount of water determined by the determination means, the predetermined time Δt and the predetermined temperature difference ΔT by was an induction heating cooker to modify a pre-determined optimum values to determine the boiling input power that said change, depending on the water volume change would input power after determining the boiling detection condition Therefore, it is possible to determine the optimum boiling detection conditions and to accurately detect the boiling.

According to a second aspect of the invention, in particular, in the first aspect of the invention, the water amount determining means controls the input power to be constant during the water amount determination when the input power changes before the water amount determination starts. since it water determination without influence of the change can be detected accurately boiling.

According to a third aspect of the invention, in particular, in the first aspect of the invention, the water amount determination means controls the input power to be constant during the water amount determination when the input power changes during the water amount determination . Since the amount of water can be determined without being affected by changes, boiling can be detected with high accuracy.

According to a fourth aspect of the invention, in particular, in the first aspect of the invention, the boiling detection means can cope with a change in the boiling detection condition by resetting the boiling detection when the input power changes during the boiling detection. Boiling can be detected.

According to a fifth aspect of the invention, in particular, in any one of the first to fourth aspects of the invention, the boiling detection means falls within a predetermined range in which the input power is not required to repeatedly perform the water amount determination after the input power is changed. By controlling in this way, it is not necessary to repeatedly determine the amount of water, so that boiling detection can be reliably performed.

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

(Embodiment 1)
1 to 3 show an induction heating cooker according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the induction heating cooker in the present embodiment includes a heating coil 3 that heats a cooking container 1 such as a pan, and a top plate 2 that holds the cooking container 1 above the heating coil 3. , A high-frequency inverter 4 for supplying a high-frequency current to the heating coil 3 to heat the cooking vessel 1 by induction heating, and an infrared ray that is installed under the top plate 2 and detects infrared rays emitted from the bottom surface of the cooking vessel 1 A detecting means 5; a temperature detecting means 6 for detecting the temperature of the cooking container 1 from the output of the infrared detecting means 5; and a water amount determining means 8 for determining the amount of water in the cooking container 1 from the output of the temperature detecting means 6. And boil detecting means 7 for controlling the power supplied to the heating coil 3 and detecting the boiling from the output of the temperature detecting means 6.

  The boiling detection means 7 changes the boiling detection condition when the input power changes after determining the boiling detection condition based on the determination of the water amount determination means 8. Thereafter, as shown in FIG. 2, the boiling detection means 7 calculates the temperature difference ΔT1 or ΔT2 of the cooking container 1 at a predetermined time Δt every second, and continuously detects that it is within the predetermined temperature difference ΔT. In this case, it is determined that the water in the cooking container 1 has boiled.

In addition, although the induction heating cooking appliance in this Embodiment is not shown in figure, it has the single or several heating part which consists of the heating coil 3, and the heating part by another means, etc., and single heating The use of the unit and the simultaneous use of the plurality of heating units can be appropriately performed as necessary.

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

  First, when a power supply (not shown) is turned on and boiling water is started with an operation switch, electric power is supplied from the high frequency inverter 4 to the heating coil 3 under the control of the boiling detection means 7. When electric power is supplied to the heating coil 3, an induction magnetic field is generated in the heating coil 3, and the cooking container 1 on the top plate 2 is heated. Due to this induction heating, the temperature of the cooking container 1 rises, and water to be heated, for example, water in the cooking container 1 boils.

  Here, when the temperature of the cooking vessel 1 rises, infrared rays corresponding to the temperature are emitted from the cooking vessel 1. Since the glass ceramic or the like used for the top plate 2 can efficiently transmit infrared rays having a wavelength range of 2.5 μm or less, the infrared detection means 5 is, for example, a photodiode that can detect wavelengths of 2.5 μm or less. The infrared rays in this wavelength range that have passed through the top plate 2 are incident on the infrared detection means 5. Moreover, the infrared detection means 5 employ | adopts the structure which condenses more infrared rays using a highly reflective specular reflector, and cuts off infrared rays from those other than the cooking container 1, and aims at the improvement of precision. Yes.

  In the temperature detection means 6, only infrared rays from the cooking container 1 enter the infrared detection means 5, and a diode current corresponding to the amount of infrared rays is subjected to IV conversion, amplified, and converted into temperature. This temperature information is input to the boiling detection means 7 and the water amount determination means 8. The water amount determination means 8 determines the amount of water in the cooking container 1 according to the output of the temperature detection means 6 and determines the boiling detection condition based thereon, and the boiling detection means 7 determines the predetermined time Δt at the time of optimal boiling detection and A predetermined temperature difference ΔT is determined. Then, as described above, the boiling detection means 7 calculates the temperature difference ΔT1 or ΔT2 at a predetermined time Δt every second, and water is detected when it is continuously detected that it is within the predetermined temperature difference ΔT. Judge that it is boiling.

  Here, for example, when switching from the use of the heating unit to the simultaneous use of the entire (plurality) of heating units, the input power of the heating unit being used becomes small as shown by the wavy line in FIG. Since the temperature change is small compared with the case where the input power is constant, the temperature difference ΔT1 to ΔT2 is reached. Nevertheless, there is a possibility that it is determined to be boiling. Therefore, when the input power changes after determining the boiling detection condition based on the determination of the water amount determination means 8, the boiling detection condition is changed to determine that the water is boiling even when the input power changes. I have to.

  Hereinafter, an example of the algorithm of the boiling detection determination method in the boiling detection means 7 will be described with reference to FIG.

  In step (hereinafter referred to as S) 1, if the input power has not changed, the process proceeds to S2, and if it has changed, the process proceeds to S5. In S2, if the temperature difference ΔT1 at the predetermined time Δt is within the predetermined temperature difference ΔT, the process proceeds to S3, and if not within the predetermined temperature difference ΔT, the process returns to S1. In S3, the number of detections n is counted. In S4, if the number of detections n is equal to or greater than the predetermined number N, the heating is terminated. In S5, it changes to the optimal boiling detection conditions according to the amount of water. In S6, the number of detections n is reset and the process returns to S1.

  Note that the predetermined time Δt and the predetermined temperature difference ΔT used for boiling detection are experimentally determined in advance as optimum values.

  As described above, in the present embodiment, if the input power changes after the boiling detection condition is determined, the optimum boiling detection condition can be determined according to the amount of water, and the boiling can be detected with high accuracy. In the above description, the boiling detection condition is changed depending on whether or not the input power at the time of boiling detection has changed, but if the change is made to a plurality of boiling detection conditions according to the input power during water volume determination, the boiling detection condition is changed. Accuracy can be improved. In addition, when the input electric power changes during boiling detection, the boiling detection means 7 can detect the boiling with high accuracy because it can cope with the change in the boiling detection condition by resetting the boiling detection.

(Embodiment 2)
4 and 5 show an induction heating cooker according to Embodiment 2 of the present invention. Since the basic configuration is the same as that of the first embodiment, differences will be mainly described.

  In the present embodiment, the water amount determination means 8 selects a water amount determination method according to the change in the input power when the input power changes before the water amount determination is started.

  FIG. 4 shows a case where the input power is constant and the input power is reduced before the water amount determination is started in the water amount determination method for determining the amount of water in the cooking container 1 based on the arrival time from the temperature determination values T1 to T2. It shows the temperature change in a graph. Assuming that the arrival time when the input power is constant is t1, and the arrival time when the input power is small, t2, the temperature change is small when the input power is small. As time increases, a relationship such as t1 <t2 is established. Since this relationship becomes prominent particularly when the amount of water is large, the accuracy of boiling detection when the amount of water is large may be deteriorated. In order to eliminate this, when the input power changes, the second water amount determination method is selected.

  An example of the algorithm of the water amount determination method will be described with reference to FIG.

  In S11, it is determined whether or not the input power has changed, and if not changed, the process proceeds to S12, and if changed, the process proceeds to S13. In S12, the amount of water in the cooking container 1 is determined according to the output of the temperature detection means 6 using the first water amount determination method. In S13, the amount of water in the cooking container 1 is determined according to the output of the temperature detection means 6 using the second water amount determination method.

  Although the water amount determination method is changed depending on whether the input power has changed, the accuracy of water amount determination can be improved by selecting from a plurality of water amount determination methods according to the degree of change in the input power.

  In addition, when performing the water volume determination using the second water volume determination method, if the input power is controlled to be constant, the water volume determination can be performed without being affected by the change in the input power. The accuracy of water volume determination can be improved.

  Furthermore, when performing the water amount determination using the second water amount determination method, the water amount determination can be performed without being affected by the change in the input power if the measurement is started after a predetermined time has elapsed from the start of the water amount determination. Therefore, the accuracy of water volume determination can be improved.

  As described above, in the present embodiment, when the input power changes before the water amount determination starts, the water amount determination unit 8 selects the water amount determination method according to the change in the input power, regardless of the input power. Since the water amount is accurately determined by the selected optimum water amount determination method, boiling can be detected with high accuracy.

(Embodiment 3)
6 and 7 show an induction heating cooker according to Embodiment 3 of the present invention. Since the basic configuration is the same as that of the first embodiment, differences will be mainly described.

  In the present embodiment, when the input power changes during the water amount determination, the water amount determination means 8 is changed to a water amount determination method according to the change in the input power.

  FIG. 6 shows a change in temperature when the input power is constant and when the input power is reduced during the water amount determination in the water amount determination method for determining the amount of water in the cooking container 1 based on the arrival time from the temperature determination value T1 to T2. Is represented in a graph. Assuming that the arrival time when the input power is constant is t3 and the arrival time when the input power is small is t4, the temperature change is small when the input power is small. As time increases, a relationship such as t3 <t4 is established. As a result, there is a possibility that the optimum boiling detection condition cannot be selected, so that the accuracy of boiling detection may be deteriorated. In order to eliminate this, when the input power changes, the second water amount determination method is selected.

  An example of the algorithm of the water amount determination method will be described with reference to FIG.

  In S21, if the temperature T calculated by the temperature detection means 6 is equal to or higher than the temperature determination value T1, the process proceeds to S22, and if it is less than the temperature determination value T1, the process returns to S21. In S22, the timer starts time measurement tt. In S23, it is determined whether or not the input power has changed, and if it has changed, the process proceeds to S24, and if it has not changed, the process proceeds to S25. In S24, the amount of water in the cooking container 1 is determined according to the output of the temperature detection means 6 using the second water amount determination method. In S25, if the temperature T calculated by the temperature detection means 6 is not less than the temperature determination value T2, the process proceeds to S26, and if it is less than the temperature determination value T2, the process returns to S23. In S26, the timer is stopped and the measurement time tt is obtained. In S27, the amount of water in the cooking container 1 is determined from the measurement time tt.

  Although the water amount determination method is changed depending on whether the input power has changed, the accuracy of water amount determination can be improved by selecting from a plurality of water amount determination methods according to the degree of change in the input power.

  In addition, when performing the water volume determination using the second water volume determination method, if the input power is controlled to be constant, the water volume determination can be performed without being affected by the change in the input power. The accuracy of water volume determination can be improved.

  Furthermore, when performing the water amount determination using the second water amount determination method, the water amount determination can be performed without being affected by the change in the input power if the measurement is started after a predetermined time has elapsed from the start of the water amount determination. Therefore, the accuracy of water volume determination can be improved.

  As described above, in the present embodiment, when the input power changes during the water amount determination, the water amount determination unit 8 changes the input amount regardless of the input power by changing to the water amount determination method according to the change in the input power. Since the water amount is accurately determined by the optimum water amount determination method, boiling can be detected with high accuracy.

(Embodiment 4)
Next, the induction heating cooker in Embodiment 4 of this invention is demonstrated.

In the present embodiment, the boiling detection means 7 controls the input power so that it falls within a predetermined range after the input power changes. The rest is the same as in the first embodiment.

  As described above, in the present embodiment, the boiling detection means 7 performs control so that the input power is within the predetermined range after the input power is changed, so that the water amount determination is not repeatedly performed. Therefore, it is possible to reliably perform boiling detection.

  As described above, the induction heating cooker according to the present invention can accurately detect boiling even when the input power changes, and thus can be applied to various induction heating cookers such as home use and business use. .

The block diagram which shows the structure of the induction heating cooking appliance in Embodiment 1 of this invention. The graph which shows the difference of the temperature change when the input electric power changes in the same induction heating cooker The flowchart which shows the processing content in the boiling detection means in the induction heating cooking appliance The graph which shows the difference in the temperature change when the input electric power of the induction heating cooking appliance in Embodiment 2 of this invention changes. The flowchart which shows the processing content in the water quantity determination means in the induction heating cooking appliance The graph which shows the difference in the temperature change when the input electric power of the induction heating cooking appliance in Embodiment 3 of this invention changes. The flowchart which shows the processing content in the water quantity determination means in the induction heating cooking appliance

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cooking container 2 Top plate 3 Heating coil 4 High frequency inverter 5 Infrared detection means 6 Temperature detection means 7 Boiling detection means 8 Water quantity determination means

Claims (5)

A plurality of heating units comprising a plurality of heating coils for heating the cooking container or a plurality of heating units including one or more heating coils and heating means other than the heating coil, and the cooking container is held above the heating coil A top plate, infrared detection means for detecting infrared rays radiated from the bottom surface of the cooking container installed under the top plate, temperature detection means for detecting the temperature of the cooking container from the output of the infrared detection means, It is determined in advance from a water amount determination means for determining the amount of water in the cooking container according to the time until the output of the temperature detection means reaches the temperature determination value T2 from the temperature determination value T1 with the input power being constant, and the output of the temperature detection means. Boiling detecting means for detecting boiling when it is detected that the temperature difference of the cooking container detected during the predetermined time Δt is within a predetermined temperature difference ΔT determined in advance ; , Wherein the boiling detecting means, the heating portion and the input power of the plurality After determining the optimum predetermined time Δt and the predetermined temperature difference ΔT to the determined amount of water of said water determining means is changed by simultaneous heating In this case, the induction heating cooker that changes the predetermined time Δt and the predetermined temperature difference ΔT to optimum values determined in advance to determine that the changed input power is boiling . The induction heating cooker according to claim 1, wherein the water amount determining means controls the input power to be constant during the water amount determination when the input power changes before the water amount determination is started. The induction heating cooker according to claim 1, wherein the water amount determination means controls the input power to be constant during the water amount determination when the input power changes during the water amount determination . The induction heating cooker according to claim 1, wherein the boiling detection means resets the boiling detection when the input power changes during the boiling detection. The induction heating cooker according to any one of claims 1 to 4 , wherein after the input power changes, the boiling detection means controls the input power to be within a predetermined range that does not require repeated water volume determination . .

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