JP2009070830A5 - - Google Patents

Description

Induction heating cooker

  The present invention relates to an induction heating cooker capable of accurately detecting boiling even when a disturbance exists.

2. Description of the Related Art Conventionally, it is known that boiling detection in an induction heating cooker is performed by a thermistor detecting the temperature of a cooking container via a top plate (see, for example, Patent Document 1).
JP 2003-7444 A

However, in the conventional configuration, depending on the shape of the bottom of the cooking container, the thermistor is not in direct contact with the bottom surface of the cooking container, so that boiling cannot be detected with high accuracy. Therefore, it is necessary to process and correct the coupling situation. there were. However, when the correction is not sufficient, there is a problem that boiling cannot be detected with high accuracy.

  This invention solves the said conventional subject, and it aims at providing the induction heating cooking appliance which can detect boiling with high precision, without performing a complicated process.

In order to solve the conventional problems, an induction heating cooker according to the present invention includes a heating coil that heats a cooking container, a top plate that holds the cooking container above the heating coil, and under the top plate. an infrared detector for detection knowledge infrared rays placed radiated from the bottom surface of the cooking vessel, a temperature detecting means for detecting a temperature of the cooking container from an output of said infrared detection means, the temperature of the detected temperature of said temperature sensing means Boiling detection means for detecting boiling by detecting that the gradient is equal to or less than a first predetermined value, and the boiling detection means has a temperature gradient of the temperature obtained from the temperature detection means. After the first predetermined value or less, when it becomes the second predetermined value or more, it is determined that there has been a spill, and heating is stopped .

Thereby, unnecessary heating can be prevented .

The induction cooking device of the present invention can prevent unnecessary heating .

1st invention is the heating coil which heats a cooking vessel, the top plate which hold | maintains the said cooking vessel above the said heating coil, and the infrared rays radiated | emitted from the bottom face of the said cooking vessel installed under the said top plate. Infrared detecting means for detecting, temperature detecting means for detecting the temperature of the cooking container from the output of the infrared detecting means, and detecting that the temperature gradient of the detected temperature of the temperature detecting means is not more than a first predetermined value. a boiling detection means for performing a boiling detection to detect boiling by the boiling detection means, after the temperature gradient of the obtained from the temperature detecting means temperature becomes below the first predetermined value or less, the When the value exceeds a predetermined value of 2, it is determined that there has been a spill , and heating is stopped, whereby unnecessary heating can be prevented.

  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 an induction heating cooker according to Embodiment 1 of the present invention.

  In the figure, an induction heating cooker supplies a high-frequency current to a heating coil 3 for heating the cooking container 1, a top plate 2 for holding the cooking container 1 disposed above the heating coil 3, and the heating coil 3, Inverter 4 that heats cooking vessel 1 by induction heating, infrared detector 5 that is installed below top plate 2 and detects infrared rays emitted from the bottom of cooking vessel 1, and cooking from the output of infrared detector 5 The temperature detection means 6 for detecting the temperature of the container 1, the thermal element 7 such as a thermistor provided so as to be in thermal contact with the lower surface of the top plate 2, and cooking via the top plate 2 from the output of the thermal element 7 A boiling temperature detector 8 for detecting the temperature of the container 1 and a power for controlling the electric power supplied to the heating coil 3 and performing the boiling detection according to the output of the temperature detecting means 6 corrected using the thermal temperature detector 8. With detection means 9And the boiling detection means 9 is formed in the structure which calculates the temperature difference in predetermined time for every second, and determines that the water has boiled when it is continuously detected that it is within the predetermined temperature difference. .

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 is started with an operation switch, the boiling detection means 9
Is supplied from the inverter 4 to the heating coil 3. 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 is aiming at the improvement of precision by condensing more infrared rays using a specular reflector with a high reflectance.

  However, the infrared detection means 5 may also detect infrared rays radiated from outside such as sunlight, and the output in this case is the sum of the infrared rays from the cooking container 1 and the infrared rays radiated from the outside. When the cooking vessel 1 is not sufficiently heated, the influence of infrared rays emitted from the outside may be dominant. Therefore, the output of the thermal element 7 that is in thermal contact with the cooking container 1 is used to check the influence of infrared rays emitted from the outside. If there is an influence, the influence of infrared rays from the cooking container 1 is dominant. Do not perform boiling detection until

  The temperature detection means 6 amplifies the diode current in accordance with the amount of infrared light incident on the infrared detection means 5 after IV conversion, and converts it into temperature. This temperature information is input to the boiling detection means 9. And when the boiling detection means 9 calculates the temperature difference in predetermined time every second when the infrared rays from the cooking vessel 1 become dominant, and continuously detects that it is within the predetermined temperature difference. Determine that the water is boiling.

  The predetermined time and the predetermined temperature difference used for boiling detection are experimentally determined in advance as optimum values.

  As described above, in the present embodiment, since the detection result of the temperature detection means 6 is corrected using the thermal temperature detection means 8, the temperature of the cooking container 1 calculated by the temperature detection means 6 via the infrared detection means 5. Can accurately detect boiling without being influenced by the shape of the bottom surface of the cooking container 1 and without performing complicated processing even if there is a disturbance.

(Embodiment 2)
2 and 3 show an induction heating cooker according to Embodiment 2 of the present invention.

  In the present embodiment, the processing content of the boiling detection means 9 in the first embodiment is embodied, and therefore, the description will focus on differences from the first embodiment.

  FIG. 2 shows the temperature from the temperature detection means 6 and the temperature from the thermal temperature detection means 8 from the start of heating. When there is an influence of infrared rays radiated from the outside (disturbance: yes), while the temperature of the cooking vessel 1 is sufficiently low, the influence of infrared rays from the outside is dominant, so there is no change in temperature, and therefore boiling detection The means 9 will judge that the time in which the water in the cooking vessel 1 is not boiling is boiling. In order to avoid this, the boiling detection means 9 performs the control flow of steps S1 to S2 shown in FIG. 3 according to the stored program, and determines whether there is an influence of infrared rays from the outside.

The operation of the boiling detecting means 9 will be described with reference to FIG. 3. In S1, the boiling detecting means 9 compares the temperature TI0 of the temperature detecting means 6 at the start of heating with the temperature Tt0 of the thermal temperature detecting means 8, and the condition of TI0 ≧ Tt0 + T0. If satisfied, the process proceeds to S2, and if not satisfied, the boiling detection means 9 performs boiling detection. In S <b> 2, a disturbance standby process is performed, and the process waits until the temperature of the temperature detection means 6 becomes dominant due to the infrared rays from the cooking container 1.

  The determination value T0 used when comparing the temperature of the temperature detection means 6 and the temperature of the thermal temperature detection means 8 is experimentally determined in advance as an optimum value. Moreover, although there is only one determination value T0, if a plurality of determination values are used and further selected from a plurality of standby steps, the accuracy of boiling detection can be improved.

  As described above, in the present embodiment, boiling detection is performed after determining whether there is an influence of infrared rays from the outside at the start of heating, and the boiling detection means 9 is a temperature detection means at the start of heating. When the difference between the detection result of 6 and the detection result of the thermal temperature detection means 8 is a predetermined value or more, the temperature of the bottom surface of the cooking container 1 is determined by determining that it is affected by infrared rays radiated from the outside. Can be detected accurately, and boiling can be detected accurately.

(Embodiment 3)
4 and 5 show an induction heating cooker according to Embodiment 3 of the present invention.

  In the present embodiment, the processing content of the boiling detection means 9 in the first embodiment is embodied, and therefore, the description will focus on differences from the first embodiment.

  FIG. 4 shows the behavior of the temperature calculated by the temperature detection means 6 when there is an influence of infrared rays emitted from the outside during heating. As is apparent from this figure, the temperature of the temperature detecting means 6 suddenly rises from the middle due to the influence of infrared rays radiated from the outside, and the temperature changes until the infrared rays from the cooking container 1 become dominant. It will disappear. For this reason, when the boiling detection is continued in this state, it is determined that the water is not boiling in the cooking container 1 as boiling. In order to avoid this, the boiling detection means 9 performs the control flow from S5 to S6 shown in FIG. 5 by the stored program, and determines whether or not there is an influence of external infrared rays.

  The operation of the boiling detection means 9 will be described with reference to FIG. 5. When the boiling detection means 9 compares the current temperature TIt with the temperature TIt-a before the predetermined time a in S5 and is larger than the temperature determination value T1, If equal, it is determined that there is an influence of infrared rays from the outside, and the process proceeds to S6. If it is smaller, boiling detection is continued. In S <b> 6, a disturbance standby process is performed, and the process waits until the temperature of the temperature detection means 6 becomes dominant due to the infrared rays from the cooking container 1.

  The predetermined time a and the temperature determination value T1 are experimentally determined in advance as optimum values. Moreover, although there is only one determination value T1, the accuracy of boiling detection can be improved if a plurality of determination values are used and further selected from a plurality of standby steps.

  As described above, in the present embodiment, boiling detection is performed while determining whether there is an influence of infrared rays from the outside during heating, and the boiling detection means 9 is obtained from the temperature detection means 6. When the temperature gradient of the measured temperature becomes a positive value greater than or equal to the predetermined value, it is judged that the infrared ray is radiated from the outside, and cooking is performed even if the infrared ray is emitted from the outside during the heating. The temperature of the bottom surface of the container 1 can be accurately detected, and boiling can be accurately detected.

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

In the present embodiment, the difference from the first to third embodiments is that the temperature obtained from the temperature detection means 6 in the boiling detection means 9 is more predetermined than the temperature at the start of the disturbance standby process. The disturbance waiting process is not terminated until the value rises above the value.

  That is, as apparent from FIGS. 2 and 4, the temperature obtained from the temperature detecting means 6 is substantially constant while being influenced by the infrared rays emitted from the outside, and the infrared rays from the cooking container 1 are dominant. Until there is a change, the temperature will disappear. For this reason, when the temperature rises by a predetermined value or more than the temperature at the start of the disturbance standby process, it can be considered that the infrared rays from the cooking container 1 have become dominant.

  In this embodiment, the standby process is terminated until the temperature obtained from the temperature detecting means 6 rises by a predetermined value or more. However, the temperature gradient may be a positive value that is a predetermined value or more. .

  As described above, in this embodiment, when it is determined that the sensor is affected by the infrared rays radiated from the outside, the detection result is predetermined based on the detection result of the temperature detection unit 6 at the time of determination. By not performing the boiling detection until the value rises above the value, erroneous boiling detection can be prevented. Further, in another example of the present embodiment, when it is determined that it is affected by infrared rays emitted from the outside, it boils until the temperature gradient of the temperature obtained from the temperature detecting means 6 becomes a predetermined value or more. By not performing detection, erroneous boiling detection can be prevented. In other words, in the present embodiment, the process waits until the temperature calculated by the temperature detecting means 6 rises by a predetermined value or more in the disturbance waiting step, and therefore, boiling detection is performed when the infrared rays from the cooking container 1 are dominant. Therefore, it is possible to detect boiling with higher accuracy.

(Embodiment 5)
6 and 7 show an induction heating cooker according to the fifth embodiment of the present invention.

  In the present embodiment, the processing content of the boiling detection means 9 in the first embodiment is embodied, and therefore, the description will focus on differences from the first embodiment.

  As shown in FIG. 6, when the water temperature at the start of heating is different, the temperature calculated by the temperature detection means 6 is the initial temperature and the temperature at the time when the temperature changes from falling to rising (hereinafter, this is called the lowest temperature). If the water temperature is Tm1 when the water temperature is high and Tm2 when the water temperature is low, the temperature decrease width increases as the water temperature decreases, and the temperature decrease width decreases as the water temperature increases. That is, a relational expression such as Tm1 <Tm2 of the temperature decrease width is established. Further, when the water temperature is nearly boiling, Tm1≈0, so that heating can be surely stopped when heating is completed for a certain period of time without performing boiling detection. Therefore, in the present embodiment, the boiling detection means 9 executes a control flow from S10 to S12 shown in FIG. 7 using a stored program, and determines whether the water temperature is high.

  Hereinafter, an example of the reheating detection algorithm will be described with reference to FIG. In S10, if the temperature TI0 of the temperature detection means 6 at the start of heating is equal to or higher than the temperature judgment value T2, the process proceeds to S11, and if it is smaller than the temperature judgment value T2, the process returns to the boiling detection process. In S11, if the temperature Tt0 of the thermal temperature detection means 8 at the start of heating is equal to or higher than the temperature determination value T3, the process proceeds to S12, and if it is smaller than the temperature determination value T3, the process returns to the boiling detection process. In S12, it is determined whether or not the lowest point temperature Tmm is confirmed. If it is confirmed, the process proceeds to S13, and if not confirmed, the process returns to S12. In S13, if the difference between the temperature TI0 of the temperature detecting means 6 at the start of heating and the lowest point temperature Tmm is smaller than the temperature judgment value T4, the process proceeds to S14, and if larger than the temperature judgment value T4, the process returns to the boiling detection process. In S14, the process ends after heating for a certain time tm.

The temperature determination values T1, T2, T3, T4 and the fixed time tm are experimentally determined in advance as optimum values.

  As described above, in the present embodiment, when the difference between the detection result of the temperature detection means 6 at the start of heating and the detection result of the thermal temperature detection means 8 is a predetermined value or more, the detection result of the temperature detection means 6 When the difference between the temperature detection result of the temperature detection means 6 during the heating and the change from the lowering to the rising is within a predetermined value, it is determined that the water temperature in the cooking container 1 is in the vicinity of boiling for a certain period of time. By heating only, unnecessary heating can be prevented.

(Embodiment 6)
8 and 9 show an induction heating cooker according to Embodiment 6 of the present invention.

  In the present embodiment, the processing content of the boiling detection means 9 in the first embodiment is embodied, and therefore, the description will focus on differences from the first embodiment.

  As shown in FIG. 8, since the spill occurs after boiling, the temperature gradient of the temperature detecting means 6 also shows a change that rises once it becomes small. Therefore, in the present embodiment, the boiling detection means 9 executes a control flow from S21 to S23 shown in FIG. 9 using a stored program, and determines whether or not a spill has occurred.

  Hereinafter, an example of an algorithm for detecting spills will be described with reference to FIG. In S21, if the temperature gradient ΔT1 of the temperature detecting means 6 is equal to or lower than the temperature determination value Ta, the process proceeds to S22, and if it is equal to or higher than the temperature determination value Ta, the process returns to S21. In S22, it is determined whether or not the temperature gradient ΔT1 of the temperature detecting means 6 has been continuously detected to be equal to or lower than the temperature determination value Ta. If continuously detected, it is determined that the water in the cooking container 1 has boiled. Then, the boiling detection is finished, and if not continuously detected, the process proceeds to S23. In S23, if the temperature gradient ΔT1 of the temperature detection means 6 is equal to or higher than the temperature determination value Tb, it is determined that the spilling has been detected, the boiling detection is terminated, and if it is smaller than the temperature determination value Tb, the process returns to S21.

  The temperature determination values Ta and Tb are experimentally determined in advance as optimum values. Further, although there is only one temperature gradient ΔT1, there may be two temperature gradients: a temperature gradient for detecting boiling and a temperature gradient for detecting spilling. In that case, both boiling detection and spill detection can be detected with higher accuracy.

  As described above, in the present embodiment, the boiling detection means 9 becomes equal to or higher than the second predetermined value after the temperature gradient of the temperature obtained from the temperature detection means 6 falls within the first predetermined value. In such a case, it is determined that there has been a spill, and heating is stopped, so that unnecessary heating can be prevented and boiling can be detected with high accuracy.

  As described above, since the induction heating cooker according to the present invention can detect boiling with high accuracy, it can be applied to various induction heating cookers for 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 influence of the external infrared rays of the induction heating cooking appliance in Embodiment 2 of this invention Flow chart showing processing contents of boiling detection means in the induction heating cooker The graph which shows the influence by the external infrared rays during the heating of the induction heating cooking appliance in Embodiment 3 of this invention Flow chart showing processing contents of boiling detection means in the induction heating cooker The graph which shows the temperature change by the difference in the initial water temperature of the induction heating cooking appliance in Embodiment 5 of this invention Flow chart showing processing contents of boiling detection means in the induction heating cooker The graph which shows the temperature change at the time of the spill of the induction heating cooking appliance in Embodiment 6 of this invention Flow chart showing processing contents of boiling detection means in the induction heating cooker

DESCRIPTION OF SYMBOLS 1 Cooking container 2 Top plate 3 Heating coil 5 Infrared detection means 6 Temperature detection means 7 Thermal element 8 Thermal temperature detection means 9 Boiling detection means T0, T1, T2, T3, T4, Ta, Tb Temperature judgment value

Claims (1)

A heating coil that heats the cooking container; a top plate that holds the cooking container above the heating coil; and an infrared detection means that is installed under the top plate and detects infrared rays emitted from the bottom surface of the cooking container. , a temperature detecting means for detecting a temperature of the cooking container from an output of said infrared detection means, the temperature gradient of the detected temperature before Symbol temperature detecting means more boil to detect that first is less than the predetermined value Boiling detection means for detecting the boiling to detect, the boiling detection means more than the second predetermined value after the temperature gradient of the temperature obtained from the temperature detection means is less than the first predetermined value Induction heating cooker that determines that there was a spill over and stops heating.