JP5546367B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker, and more particularly to preheating of a frying pan.

Conventionally, an induction heating cooker is provided with a thermistor, an infrared sensor, and a temperature detecting means for converting the temperature of the cooking container by the output of the thermistor and the energy received by the infrared sensor, and the temperature gradient is more than a predetermined value. If the temperature is larger, give priority to the detection temperature of the infrared sensor. If it is lower than the specified value, use an induction heating cooker that gives priority to the detection temperature of the thermistor (hereinafter referred to as contact temperature sensor). In the case of changing to, one that prevents the ignition of oil or the deformation of the cooking container is known by suppressing the heating power amount or stopping the heating (for example, Patent Document 1).
In addition, there is known one that detects the temperature of a cooking container with good responsiveness so that the light receiving sensitivity wavelength region of the infrared sensor overlaps with the infrared transmission wavelength region of the top plate (for example, see Patent Document 2).

JP 2008-41471 A (page 1 to page 3, page 7) JP 2001-63881 A (page 1 to page 5, FIG. 1)

The conventional examples described in Patent Document 1 and Patent Document 2 are equipped with a preheating function that ends preheating with an appropriate heating power and at an appropriate time. When preheating a pan, It is assumed that the room temperature frying pan is placed and preheating is performed.
However, when preheating is performed by placing a frying pan at room temperature on a high-temperature top plate immediately after cooking, or when the preheating is performed on a high-temperature top plate immediately after cooking There is also a case where preheating is performed by placing the. In such a case, a new problem occurs when a contact-type temperature sensor such as a thermistor or an infrared sensor that is in contact with the back surface of the top plate is erroneously detected. For example, when preheating by placing a frying pan at room temperature on a high temperature baking sheet immediately after cooking, the contact temperature sensor and infrared sensor falsely detect that the frying pan is already hot, so preheating There arises a problem that the process is terminated earlier than a predetermined time.
In addition, when preheating is performed by placing a frying pan that has already been heated to a high temperature on a high temperature baking sheet immediately after cooking, the infrared sensor and contact temperature sensor detect the temperature through the baking sheet. As a result, the top plate heat is detected. Therefore, it becomes difficult for the control means to detect whether or not the frying pan has reached a predetermined preheating temperature based on the temperature detected by the contact temperature sensor or the infrared sensor. Therefore, even if the temperature of the frying pan reaches the preheating temperature, the user may operate the preheating start button again. In this case, there is a problem that the preheating time of the frying pan is extended. is there. In this case, the frying pan is overheated, resulting in a dangerous situation in which the fluorine coating is damaged or the frying pan is deformed.

The present invention has been made to solve such problems, and preheating is performed by placing an object to be heated (for example, a frying pan) at a room temperature or a temperature higher than the top plate on a high temperature top plate. Even in the case, an object of the present invention is to provide an induction heating cooker that can normally and safely preheat an object to be heated .

An induction heating cooker according to the present invention includes a top plate on which an object to be heated is placed, a heating coil that is provided below the top plate and induction-heats the object to be heated, and supplies AC power to the heating coil. An inverter circuit, a contact-type temperature sensor that detects the heat of the heated object in contact with the back surface of the top plate, an infrared sensor that detects infrared energy of the heated object, and an output of the contact-type temperature sensor And a temperature detecting means for converting the output of the infrared sensor into temperature, and when the object to be heated is placed on the top plate, the heating object is preheated by induction heating of the heating coil. and a control means having a preheating function to control the inverter circuit, and said control means, when the induction heating by prior Ki予 heat function is performed, the temperature detection output of the contact temperature sensor Based on the temperature detection means is converted, before Symbol calculates the gradient of the first temperature change of the heated object, based on the output of the infrared sensor to the temperature of the temperature detecting means in terms of the object to be heated Calculating a gradient of the second temperature change, and when both the gradient of the first temperature change and the gradient of the second temperature change exceed a first specified value, or when both of the gradient of the gradient and the second temperature change of less than the first predetermined value smaller than the second predetermined value, said at preheat function, upper limit temperature and the infrared sensor for the contact temperature sensor At least one of the upper limit temperatures for use is changed.

According to the present invention, the control means, based on an output of the contact temperature sensor to the temperature of the temperature detecting means is converted to calculate the slope of the first temperature change before Symbol object to be heated, the infrared sensor On the basis of the temperature converted by the temperature detection means, the gradient of the second temperature change of the object to be heated is calculated, and both the gradient of the first temperature change and the gradient of the second temperature change are calculated. Exceeds a first specified value, or when both the gradient of the first temperature change and the gradient of the second temperature change are equal to or less than a second specified value that is smaller than the first specified value. the in preheat function, since changing at least one of the upper limit temperature and the upper limit temperature for the infrared sensor for the contact-type temperature sensor, by performing the preheating on the basis of the changed upper limit temperature, the hot The top plate In the case of performing the preheating by placing the hot object to be heated than the top plate also makes it possible to safely and reliably perform the preheating of the object to be heated.

It is a perspective view which shows the external appearance of the induction heating cooking appliance which concerns on this invention. It is a block diagram which shows the structure of the control system in Embodiment 1 of the induction heating cooking appliance which concerns on this invention. It is a flowchart which shows the main process of the control means 6 in Embodiment 1 of the induction heating cooking appliance which concerns on this invention. It is a flowchart which shows the frying pan pre-heating of the control means 6 in Embodiment 1 of the induction heating cooking appliance which concerns on this invention. It is a table | surface which shows the correction value of the limit temperature for frying pan preheating in Embodiment 1 of the induction heating cooking appliance which concerns on this invention. It is explanatory drawing which shows the change of the detection temperature of the contact-type temperature sensor and infrared sensor in the frying pan pre-heat processing of Embodiment 1 of the induction heating cooking appliance which concerns on this invention. It is a flowchart which shows the frying pan pre-heat treatment of the control means 6 in Embodiment 2 of the induction heating cooking appliance which concerns on this invention. It is a table | surface which shows the correction value of the frying pan preheating time in Embodiment 2 of the induction heating cooking appliance which concerns on this invention.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing the appearance of an induction heating cooker according to the present invention, and FIG. 2 is a block diagram showing the configuration of a control system in Embodiment 1 of the induction heating cooker according to the present invention.
As shown in FIG. 1, an induction heating cooker 100 includes a main body 1 and a heat-resistant glass top plate 2 on which an upper surface of the main body 1 is formed and an object to be heated such as a pan is placed. A heating part mark 3 indicating the positions of three heating parts for induction heating of the object to be heated is disposed below the top plate 2. Specifically, a heating part mark 3a on the left side, a heating part mark 3b on the right side, and a heating part mark 3c on the rear side are arranged as viewed from the front (from arrow A in FIG. 1).
A heating coil 4 is disposed below the top plate 2 so as to correspond to each of the three heating unit marks 3 on the top plate 2. That is, the heating coil 4a is disposed directly below the heating part mark 3a, the heating coil 4b is disposed directly below the heating part mark 3b, and the heating coil 4c is disposed directly below the heating part mark 3c.

  As shown in FIG. 2, the main body 1 has an inverter circuit 5 for supplying high-frequency power to the heating coils 4a, 4b and 4c, a control means 6 for controlling the inverter circuit 5, and a time measuring means 7 for calculating time. Is mounted in a state of being accommodated in a substrate case (not shown). The control means 6 is constituted by a microcomputer, a DSP, a microprocessor, etc., and has a storage means (not shown) built therein. The installation location of the printed circuit board may be anywhere as long as it is far from the heat generation location and in the coolable air path, but it is preferably arranged upstream of the heating coil 4 from the viewpoint of cooling efficiency. Although not described in detail because it is not related to the present invention, cooling fans (not shown) are installed on both sides of the lower back of the main body 1 to suck in air from the outside of the main body 1 and print circuit boards (see FIG. (Not shown) and cooling air are sent to the heating coil 4 to cool them, and then the process proceeds rearward and is exhausted out of the main body 1 through an exhaust port formed at the rear of the main body 1. As shown in FIG. 1, a grill 9 is provided at the lower portion of the main body 1 so that it can be pulled out, and cooking of grilled dishes such as fish is possible.

Further, an operation unit 8 as an operation means is provided on the right side of the lower part of the main body 1 as shown in FIG. 1, and the user operates the operation unit 8 to adjust the heating output and induction heating cooking. Operation / setting information such as settings on the instrument can be input. The operation unit 8 includes an operation unit for the grill 9.
In addition, although the three heating coils 4a, 4b, and 4c constitute a so-called three-neck heating unit, a radiant heater having substantially the same diameter may be disposed instead of the heating coil 4c.
Further, one or more contact-type temperature sensors 11 such as a thermistor are disposed on the back surface (the surface corresponding to the heating coil 4) in the area of the heating part mark 3 of the top plate 2. Note that the object to be heated is the frying pan 10 here. Further, below the top plate 2, an infrared sensor 12 is arranged for each heating unit so as to detect infrared energy emitted from the bottom of the frying pan 10 through the top plate 2. Further, below the top plate 2 is provided temperature detecting means 13 for A / D converting the detection signal of the contact temperature sensor 11 and the infrared energy received by the infrared sensor 12 into the temperature of the frying pan 10. The converted temperature information is output to the control means 6.
The contact temperature sensor 11 may be referred to as TH. Similarly, the infrared sensor 12 may be referred to as IR.

FIG. 3 is a flowchart showing a main process of the control means 6 in the first embodiment of the induction heating cooker according to the present invention, and FIG. 4 shows the control means in the first embodiment of the induction heating cooker according to the present invention. 6 is a flowchart showing pre-heat treatment of No. 6 frying pan. Moreover, FIG. 5 is a table | surface which shows the correction value of the limit temperature for frying pan preheating in Embodiment 1 of the induction heating cooking appliance which concerns on this invention. Moreover, FIG. 6 is explanatory drawing which shows the change of the detection temperature of the contact-type temperature sensor and infrared sensor in the frying pan pre-heat processing of Embodiment 1 of the induction heating cooking appliance which concerns on this invention.
Next, operation | movement of the control means 6 in this Embodiment 1 is demonstrated using FIGS.
When the power switch (not shown) of the induction heating cooker 100 is turned on by the user, the control means 6 is activated. In the main process shown in FIG. 3, the control means 6 first performs an initial process such as clearing the counter held therein or setting an initial value (step S301), and then set by the user from the operation unit 8. Information is input (step S302). Next, the control means 6 checks whether or not the input setting information is a frying pan preheating start command (step S303), and if cooking is not started, returns to step S302 and repeats the same processing as described above to repeat the frying pan preheating start command. Wait for input. In this state, when the user places the frying pan 10 on the top plate 2 and subsequently presses the frying pan preheating start switch, a frying pan preheating start command signal is generated from the operation unit 8 and input to the control means 6. When inputting the frying pan preheating start command in step S303, the control means 6 starts the frying pan preheating software (step S304), and then returns to step S302. Thereby, the frying pan pre-heat treatment shown in FIG. 4 starts operation.

When the frying pan preheating start command is not input in step S303, the process returns to step S302.
The setting information includes various other cooking start instructions, but is not a subject of the present invention, and thus illustration and description thereof are omitted.

Next, the operation of the frying pan pre-heat treatment shown in FIG. 4 will be described.
When the function of pre-heat treatment for the frying pan is activated, the control unit 6 firstly converts the output of the contact temperature sensor 11 (TH) from the temperature detection unit 13 into the temperature converted by the temperature detection unit 13 and the infrared sensor 12 (IR). The detected temperature is acquired (step S401). Next, the control means 6 determines whether or not the temperature converted by the temperature detection means 13 from the output of the contact temperature sensor 11 is equal to or higher than the reference value Ta (step S402), and if lower than the reference value, the temperature of the frying pan 10 is determined. It is determined that the temperature is not high, and the process jumps to step S406. In step S402, when the detected temperature of the contact temperature sensor 11 is equal to or higher than the reference value Ta (YES), the control means 6 determines that the temperature of the frying pan 10 is relatively high. In this case, preheating is still performed. Without performing, the first temperature change of the frying pan 10 is calculated based on the output of the contact temperature sensor 11 (thermistor), and the second temperature change of the frying pan 10 is calculated based on the output of the infrared sensor, The calculated first temperature change or second temperature change is continuously monitored for a predetermined time (for example, 30 seconds). During this time, the first temperature change amount (ie, the gradient) calculated based on the output of the contact temperature sensor 11 and the second temperature change amount (ie, the gradient) calculated based on the output of the infrared sensor 12 (ie, the gradient). (Gradient) is checked, and it is determined whether the temperature of the frying pan 10 on the top plate 2 at that time is high or low (steps S403 to S404).
For example, when the frying pan 10 that is hotter than the top plate 2 is placed on the top plate 2, the detection temperature of the contact-type temperature sensor 11 and the detection temperature of the infrared sensor 12 gradually increase. Conversely, when a frying pan 10 that is colder than the top plate 2 is placed on the top plate 2, the detected temperature of the contact temperature sensor 11 and the detected temperature of the infrared sensor 12 gradually decrease.

Next, based on the first temperature change gradient calculated based on the output of the contact-type temperature sensor 11 and the second temperature change gradient calculated based on the output of the infrared sensor, the control means 6 performs FIG. The limit value for the contact temperature sensor 11 and the limit value for the infrared sensor 12 are acquired by referring to the table shown in FIG. The limit temperature is changed (step S405). For example, when the first temperature calculated based on the output of the contact temperature sensor 11 and the second temperature calculated based on the output of the infrared sensor 12 have dropped by 10 ° C. or more during 30 seconds, the control means 6 By referring to the table of FIG. 5, + 10 ° C. and + 10 ° C. are acquired as the correction values β 1 and β 2, respectively. Then, the limit temperature for the contact-type temperature sensor 11 and the limit temperature for the infrared sensor 12 are each increased by 10 ° C. by this correction value. Further, when the gradient of the first temperature change calculated based on the output of the contact temperature sensor 11 and the gradient of the first temperature change calculated based on the output of the infrared sensor 12 are higher than 10 ° C., the control is performed. The means 6 obtains −10 ° C. and −10 ° C. as the correction values β1 and β2 by referring to the table of FIG. Then, the limit temperature for the contact-type temperature sensor 11 and the limit temperature for the infrared sensor 12 are each lowered by 10 ° C. by this correction value (step S405).
The table in FIG. 5 is a matrix of the first temperature change gradient calculated based on the output of the contact temperature sensor 11 and the first temperature change gradient calculated based on the output of the infrared sensor 12, FIG. 5 is a table in which correction values for limit temperatures are stored in cells corresponding to respective rows and columns, and the control means 6 places a frying pan 10 higher in temperature than the top plate 2 on the high temperature top plate 2 based on the correction values. The limit temperature is changed by determining whether or not the frying pan 10 that is cooler than the top plate 2 is placed on the high-top plate 2.
In addition, ΔT in the table is a change amount (that is, a gradient) of temperature based on the sensor output in a predetermined time (here, 30 seconds).

  Next, the control means 6 controls the inverter circuit 5 to preheat the frying pan 10 by induction heating of the heating coil 4 (step S406). Next, the control means 6 determines whether the temperature of the frying pan 10 converted by the temperature detecting means 13 based on the output of the contact temperature sensor 11 or the temperature of the frying pan 10 converted by the temperature detecting means 13 based on the output of the infrared sensor 12. It is checked whether or not the temperature reaches the limit temperature (steps S407 to S408). If either one reaches the limit temperature or more, the temperature of the frying pan 10 is a dangerously high temperature, so the frying pan pre-heat treatment is terminated. If none of them reaches the limit temperature or more, it is determined whether or not the preheating time of the frying pan 10 has elapsed (step S409). If the preheating heating time of the frying pan 10 has not yet elapsed, the process proceeds to step S406. Returning, steps S406 to S409 are repeated until the temperature reaches the limit temperature or until the preheating heating time of the frying pan elapses. When the preheating heating time of the frying pan has elapsed, the frying pan preheating treatment is finished.

Here, frying pan preheating operation will be described with reference to FIG.
Frying pan preheating consists of a preheating step and a subsequent heat retention step. In the preheating process, a predetermined heating power, for example, 1000 W is supplied to the heating coil 4, and the temperature of the frying pan 10 gradually rises due to preheating by induction heating. Is finished before the temperature of the frying pan 10 converted by the temperature detection means 13 based on the output of the above reaches the limit temperature for the contact-type temperature sensor 11. The same applies to the infrared sensor 12, and the process ends before the temperature of the frying pan 10 converted by the temperature detecting means 13 based on the output of the infrared sensor 12 due to timeout reaches the limit temperature for the infrared sensor 12. Thereafter, the heat insulation process is started, and a predetermined heating power smaller than that in the preheating process, for example, 500 W is supplied to the heating coil 4, and the temperature of the frying pan 10 is maintained at a substantially constant temperature until the heat insulation process is completed by preheating by induction heating.

  According to the first embodiment, in the frying pan pre-heat treatment, the control means 6 uses the first temperature of the frying pan 10 from the frying pan 10 temperature converted by the temperature detecting means 13 based on the output of the contact temperature sensor 11 as described above. The temperature change gradient is calculated, the control means 6 calculates the second temperature change of the frying pan 10 from the temperature of the frying pan 10 converted by the temperature detection means 13 based on the output of the infrared sensor, and the first temperature change gradient is calculated. The correction value is obtained by referring to the table of FIG. 5 based on both the gradient of the second temperature change and the limit temperature for the contact-type temperature sensor 11 in the preheating function of the frying pan 10 based on this correction value ( At least one of the upper limit temperature) and the limit temperature (upper limit temperature) for the infrared sensor 12, and the preheating is executed based on the changed upper limit temperature. In, the high temperature of the top plate, even in the case of performing the preheating by placing the hot frying pan than the room temperature or the top plate, it is possible to safely and reliably perform the preheating of the frying pan.

  In the above example, contact is made based on the gradient of the first temperature change of the frying pan 10 calculated from the output of the contact temperature sensor and the gradient of the second temperature change of the frying pan 10 calculated from the output of the infrared sensor. Although it has been described that at least one of the limit temperature (upper limit temperature) for the formula temperature sensor 11 and the limit temperature (upper limit temperature) for the infrared sensor 12 is changed, it is not necessary to limit the change only. For example, for the contact temperature sensor 11 based on the gradient of the first temperature change of the frying pan 10 calculated from the output of the contact temperature sensor and the gradient of the second temperature change of the frying pan 10 calculated from the output of the infrared sensor. At least one of the limit temperature (upper limit temperature) and the limit temperature (upper limit temperature) for the infrared sensor 12 may be set.

Embodiment 2. FIG.
1-3 and 6 are also used in this embodiment.
FIG. 7 is a flowchart showing the frying pan pre-heat treatment of the control means 6 in Embodiment 2 of the induction heating cooker according to the present invention. Moreover, FIG. 8 is a table | surface which shows the correction value of the frying pan preheating time in Embodiment 2 of the induction heating cooking appliance which concerns on this invention.
The flowchart in FIG. 7 is the same as FIG. 4 except that step S405 in FIG. 4 is replaced with step S701. In step S <b> 701, the control unit 6 displays the first temperature change gradient calculated based on the output of the contact temperature sensor 11 and the second temperature change gradient calculated based on the output of the infrared sensor 12. The correction value of the preheating time is acquired by referring to the table shown in FIG. 8, and the preheating time is changed by this correction value. For example, when the first temperature change gradient calculated based on the output of the contact temperature sensor 11 and the second temperature change gradient detection calculated based on the output of the infrared sensor 12 are lowered by 10 ° C. or more, the control means 6 obtains +30 seconds as a correction value by referring to the table of FIG. The preheating time is extended by 30 seconds with this correction value. Further, when the first temperature change gradient calculated based on the output of the contact temperature sensor 11 and the second temperature change gradient detection calculated based on the output of the infrared sensor 12 rise higher than 10 ° C., The control means 6 acquires -30 seconds as a correction value by referring to the table of FIG. The preheating time is shortened by 30 seconds by this correction value.

  According to the second embodiment, in the pre-heat treatment of the frying pan, the gradient of the first temperature change of the frying pan 10 is calculated from the temperature converted by the temperature detection means 13 as described above, and the infrared temperature of the frying pan 10 is calculated. A gradient of the second temperature change of the frying pan 10 is calculated from the temperature obtained by converting the output of the sensor 12 by the temperature detection means 13, and based on both the gradient of the first temperature change and the gradient of the second temperature change, FIG. By referring to the table, the correction value of the preheating time is obtained, the preheating time of the frying pan 10 is changed by this correction value, and the preheating is executed based on the changed preheating time. Even when preheating is performed by placing the frying pan 10 at room temperature or higher than the top plate, the frying pan 10 can be preheated safely and reliably.

  In the above example, preheating is performed based on the gradient of the first temperature change of the frying pan 10 calculated from the output of the contact temperature sensor and the gradient of the second temperature change of the frying pan 10 calculated from the output of the infrared sensor. Although we have described changing the time, it is not necessary to limit the change. For example, the preheating time is set based on the gradient of the first temperature change of the frying pan 10 calculated from the output of the contact temperature sensor and the gradient of the second temperature change of the frying pan 10 calculated from the output of the infrared sensor. Also good.

1 induction heating cooker body, 2 top plate, 3, 3a-3c heating part mark, 4, 4a-4c
Heating coil, 5 inverter circuit, 6 control means, 7 timing means, 8 operation part, 9 grill, 10 frying pan, 11 contact temperature sensor (thermistor), 12 infrared sensor, 13 temperature detection means, 100 induction heating cooker.

Claims (4)

A top plate on which the object to be heated is placed;
A heating coil provided below the top plate for induction heating the object to be heated;
An inverter circuit for supplying AC power to the heating coil;
A contact-type temperature sensor that contacts the back surface of the top plate and detects the heat of the object to be heated;
An infrared sensor for detecting infrared energy of the heated object;
Temperature detection means for converting the output of the contact-type temperature sensor and the output of the infrared sensor into a temperature;
When the object to be heated is placed on the top plate, said control means having an object to be heated the that controls the inverter circuit preheating function to carry out by induction heating of the heating coil to preheat the Prepared,
Wherein, prior to the time of induction heating is performed by Ki予 heat function, based on the output of the contact temperature sensor to the temperature of the temperature detecting means is converted, the first temperature change of the heated object And a gradient of the second temperature change of the object to be heated is calculated based on the temperature converted by the temperature detecting means, and the gradient of the first temperature change and the gradient of the first temperature change are calculated. When both of the second temperature change gradients exceed the first specified value, or both of the first temperature change gradient and the second temperature change gradient are smaller than the first specified value. when: the second predetermined value, the induction heating cooker wherein the at preheat function, changing at least one of the upper limit temperature and the upper limit temperature for the infrared sensor for the contact-type temperature sensor. The control means has at least one of the gradient of the first temperature change, the gradient of the second temperature change, the correction value of the upper limit temperature for the contact-type temperature sensor, and the correction value of the upper limit temperature for the infrared sensor. Based on the corresponding table, at least one of the upper limit temperature of the contact-type temperature sensor and the upper limit temperature of the infrared sensor is changed, and preheating of the object to be heated is executed based on the changed upper limit temperature. The induction heating cooker according to claim 1. A top plate on which the object to be heated is placed;
A heating coil provided below the top plate for induction heating the object to be heated;
An inverter circuit for supplying AC power to the heating coil;
A contact-type temperature sensor that contacts the back surface of the top plate and detects the heat of the object to be heated;
An infrared sensor for detecting infrared energy of the heated object;
Temperature detection means for converting the output of the contact-type temperature sensor and the output of the infrared sensor into a temperature;
When the object to be heated is placed on the top plate, said control means having an object to be heated the that controls the inverter circuit preheating function to carry out by induction heating of the heating coil to preheat the Prepared,
Wherein, prior to the time of induction heating is performed by Ki予 heat function, based on the output of the contact temperature sensor to the temperature of the temperature detecting means is converted, the first temperature change of the heated object And a gradient of the second temperature change of the object to be heated is calculated based on the temperature converted by the temperature detecting means, and the gradient of the first temperature change and the gradient of the first temperature change are calculated. When both of the second temperature change gradients exceed the first specified value, or both of the first temperature change gradient and the second temperature change gradient are smaller than the first specified value. induction cooking device, characterized in that when: a second predetermined value, to change the pre-heating heating time in the preheating function. It said control means changes the preheating heating time based on said first and slope of the gradient and the second temperature change of temperature change, and the correction value before Ki予 heat the heating time in correspondence table, changes The induction heating cooker according to claim 3, wherein preheating of the object to be heated is performed based on the preheated heating time.

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