JP5104692B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker that heats an object to be heated by a plurality of heating coils using electromagnetic induction.

An induction heating cooker that induction-heats an object to be heated such as a pan with a heating coil has been widely used in recent years because of its excellent features of safety, cleanliness, and high efficiency. Patent Document 1 discloses an induction heating cooker that is arranged concentrically, includes inner and outer coils having different diameters, and alternately supplies high-frequency power to the inner and outer coils. The outer coil is stopped when the inner coil is heating the object to be heated, and the inner coil is stopped when the outer coil is heating the object to be heated. Thereby, a convection arises in the to-be-cooked object in a to-be-heated object, and a to-be-cooked object is heated uniformly.
Japanese Patent No. 2978069

  For example, when a cold curry is warmed, until the curry is warmed to some extent, the curry has a high viscosity and convection does not occur. Therefore, the temperature rises partially, and the curry will be burnt if it is not stirred. Thus, when heating a to-be-cooked object with high viscosity, convection does not occur in the object to be cooked even by the method of Patent Document 1, and heat is transferred only locally, so the object to be cooked is heated uniformly. I can't. In addition, when the inner coil and the outer coil are alternately operated as in Patent Document 1, the temperature of the operation pause portion of the alternate operation is reduced by natural heat dissipation, and thus energy for the temperature reduction must be added every time when the operation is restarted. Therefore, there also exists a problem that heating efficiency becomes low.

  The present invention solves the above-described problems, and convection-promoting heating is performed on a low-viscosity cooking object, and uniform heating is also possible on a high-viscosity cooking object, and induction heating is performed with high heating efficiency. The purpose is to provide a cooker.

  An induction heating cooker according to the present invention is an induction heating cooker that has at least a first heating coil and a second heating coil and heats an object to be heated. Measures the degree of viscosity, determines that the viscosity is low when the degree of viscosity is within a predetermined range, and otherwise determines that the viscosity is high and the viscosity determination unit determines that the viscosity is low When one of the first heating coil and the second heating coil is operated so that convection occurs in the cooking object, and the viscosity determination unit determines that the viscosity is high, the first heating coil and And a controller for operating both of the second heating coils.

  When the viscosity determination unit determines that the viscosity is high, the control unit is configured to heat the portion to be heated that is heated by the first heating coil and the portion to be heated that is heated by the second heating coil. You may control operation | movement of a 1st heating coil and a 2nd heating coil so that temperature difference of may become small.

  When the viscosity determination unit determines that the viscosity is high, the control unit supplies the electric power per unit time to one of the first heating coil and the second heating coil so that the temperature difference is small. May be adjusted.

  The control unit may adjust the amount of power supplied per unit time by duty-controlling the power supplied to any one of the heating coils.

  The control unit may adjust the amount of power supplied per unit time by controlling the amplitude of the power supplied to any one of the heating coils.

  A first temperature measuring unit that measures the temperature of the part of the object to be heated that is heated by the first heating coil, and a second that measures the temperature of the part of the object to be heated that is heated by the second heating coil. The viscosity determination unit further includes a temperature increase rate of the heated object measured by the first temperature measuring unit and a temperature of the heated object measured by the second temperature measuring unit. If the rate of increase in the ratio is substantially the same, it may be determined that the viscosity is low, and in other cases, it may be determined that the viscosity is high.

  The first heating coil and the second heating coil may be coils having different diameters provided on the same plane.

  According to the present invention, the viscosity is determined based on the degree of viscosity. When the viscosity of the food to be cooked is low, one heating coil is operated, and when the viscosity of the food to be cooked is high, both heating coils are connected. Make it work. For this reason, in the case of a to-be-cooked object with low viscosity, uniform heating can be performed even in the case of a to-be-cooked object having high viscosity while performing convection promoting heating. Furthermore, the cooking object can be efficiently heated.

Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, the same constituent elements are given the same numbers.
Embodiment 1
[Configuration of induction heating cooker]
The structure of the induction heating cooking appliance by Embodiment 1 of this invention is shown in FIG. The induction heating cooker 1 of the present embodiment is made of an electrically insulating material such as glass and is made of a crystallized ceramic top plate 2 that transmits light, a first heating coil 3 provided below the top plate 2, and The second heating coil 4, the first high-frequency power supply unit 5 that supplies high-frequency power to the first heating coil 3, and the second high-frequency power supply unit 6 that supplies high-frequency power to the second heating coil 4 And a control unit 7 for controlling the first high-frequency power supply unit 5 and the second high-frequency power supply unit 6. The first heating coil 3 and the second heating coil 4 are spiral heating coils having different diameters arranged concentrically when viewed from the upper surface of the top plate 2. The diameter of the 1st heating coil 3 is larger than the diameter of the 2nd heating coil 4, and when the same electric power is supplied, the thermal power of the 1st heating coil 3 becomes larger than the thermal power of the 2nd heating coil 4. The 1st heating coil 3 and the 2nd heating coil 4 emit the induction magnetic field, and heat the to-be-heated object 8 mounted in the top plate 2, thereby causing the to-be-cooked object 9 in the to-be-heated object 8 to move. Heat. The first and second high frequency power supply units 5 and 6 control the amount of power supplied to the heating coils 3 and 4 by controlling the current supplied to the heating coils 3 and 4.

The induction heating cooker 1 of the present embodiment is provided on the first heating coil 3, and a first temperature measurement unit 10 that measures the temperature of the object to be heated 8 heated by the first heating coil 3, A second temperature measuring unit 11 that is provided on the second heating coil 4 and measures the temperature of the heated object 8 heated by the second heating coil 4, the first temperature measuring unit 10, and the second temperature measuring unit 10 A viscosity determination unit 12 that determines the viscosity of the cooking object 9 in the heated object 8 based on the temperature of the heated object 8 measured by the temperature measuring unit 11 and determines the viscosity based on the viscosity; It has further. A method for determining the viscosity of the item 9 will be described later.

  The control unit 7 starts and stops the supply of the high-frequency current to the first heating coil 3 and the second heating coil 4 and supplies the high frequency based on the viscosity of the cooking object 9 determined by the viscosity determination unit 12. A control signal for instructing the magnitude of the current is output to the first high-frequency power supply unit 5 and the second high-frequency power supply unit 6 to control the operations of the first heating coil 3 and the second heating coil 4. .

  FIG. 2 shows a state of the cooking object 9 in the heating object 8 when both the first heating coil 3 and the second heating coil 4 are operated simultaneously. FIG. 2A shows a case where the cooking object 9 has a high viscosity. In this case, convection does not occur in the object 9 and heat is only transferred locally. Therefore, the cooking object 9 is heated only by the portion 20 on the first heating coil 3 and the portion 21 on the second heating coil 4. Here, since the heating power of the first heating coil 3 is larger than the heating power of the second heating coil 4, the rate of increase in the temperature of the heated object 8 measured by the first temperature measurement unit 10 is the second temperature. It becomes larger than the rate of temperature increase of the article 8 to be heated measured by the measuring unit 11.

FIG.2 (b) is a case where the viscosity of the to-be-cooked item 9 is medium. In this case, a little convection is generated in the item 9 to be cooked. FIG.2 (c) is a case where the viscosity of the to-be-cooked item 9 is low. For example, water. In this case, convection occurs in the object 9 to be cooked, the object 9 is heated uniformly, and the rate of increase in the temperature of the object 8 measured by the first temperature measuring unit 10 and the second temperature measuring unit. 11, the temperature increase rate of the article 8 to be heated is substantially the same.
[Operation of induction heating cooker]
In the induction heating cooker of this embodiment, the viscosity of the cooking object is determined. When the viscosity is low, convection promotion heating is performed, and when the viscosity is high, uniform heating is performed. The viscosity determination unit 12 is configured such that the difference between the rate of increase in the temperature of the heated object 8 measured by the first temperature measurement unit 10 and the rate of increase in the temperature of the heated object 8 measured by the second temperature measurement unit 11 ( When the degree of viscosity is less than the predetermined value α, it is determined that the viscosity is low, and when the degree of viscosity is equal to or higher than the predetermined value α, it is determined that the viscosity is high.

  The details of this operation will be described with reference to FIG. FIG. 3 shows a flowchart of operation control of the heating coils 3 and 4 by the induction heating cooker according to the first embodiment of the present invention. Hereinafter, the temperature of the heated object 8 measured by the first temperature measuring unit 10 is H1, the temperature of the heated object 8 measured by the second temperature measuring unit 11 is H2, and the first temperature measuring unit 10 The rising rate of the temperature of the heated object 8 to be measured is represented by ΔH1, and the rising rate of the temperature of the heated object 8 measured by the second temperature measuring unit 11 is represented by ΔH2.

  When heating is started, the control unit 7 sets an initial value (temperature H1 + predetermined value β) as the reference temperature Hx (S101). The predetermined value β is, for example, 10 ° C. The controller 7 supplies a predetermined amount of constant power to the first heating coil 3 and the second heating coil 4 (S102). That is, PWM (Pulse Width Modulation) control is performed with a duty ratio of 100%. The electric power supplied here is determined by the magnitude of the thermal power input by the user and the cooking method. Thereafter, the viscosity determination unit 12 determines whether the viscosity is high or low. Specifically, the viscosity determination unit 12 obtains the temperature increase rates ΔH1 and ΔH2 based on the temporal change in temperature measured by the first temperature measurement unit 10 and the second temperature measurement unit 11 (S103). Next, the viscosity determination unit 12 obtains the difference (ΔH1−ΔH2) between the temperature increase rate ΔH1 and the temperature increase rate ΔH2 as the degree of viscosity, and determines whether the degree of viscosity is less than a predetermined value α (S104). The predetermined value α is a value by which it can be determined that the temperature increase rate ΔH1 and the temperature increase rate ΔH2 are substantially the same. When the degree of viscosity is less than the predetermined value α, the viscosity determination unit 12 determines that the viscosity of the object to be cooked is “low”, and when the degree of viscosity is equal to or greater than the predetermined value α, the viscosity of the object to be cooked is “high”. Judge.

  When it is determined that the viscosity of the cooking object is high (No in S104), the control unit 7 waits until the temperature H1 becomes equal to or higher than the reference temperature Hx (S105). When the control unit 7 determines that the temperature H1 has become equal to or higher than the reference temperature Hx, by supplying power to the first heating coil 3 intermittently, the amount of power per unit time becomes the first in step S101. Electric power is supplied so as to be ½ of the electric energy per unit time supplied to the heating coil 3 (S106). That is, PWM control is performed with a duty ratio of 50%. Next, the control unit 7 waits until the temperature H2 becomes equal to or higher than the reference temperature Hx (S107). When the controller 7 determines that the temperature H2 has become equal to or higher than the reference temperature Hx, a predetermined amount of constant power is supplied to the first heating coil 3 (S108). A predetermined value β is added to the reference temperature Hx (S109), and the process returns to step S103.

In step S105 to step S108, the temperature of the heated object 8 heated by the first heating coil 3 and the temperature of the heated object 8 heated by the second heating coil 4 are made uniform, that is, heated Controlled uniform heating is performed so that the temperature difference at the bottom of the object 8 is reduced. In step S106, electric power that is ½ of the electric power supplied to the first heating coil 3 in step S101 is supplied. Preferably, the temperature increase rate ΔH1 by the first heating coil 3 is substantially zero. The power to be supplied is not limited to a value of 1/2, and the supplied power may be duty-controlled. In this embodiment, the degree of viscosity is the difference between the temperature increase rate ΔH1 and the temperature increase rate ΔH2, but it may be the ratio (ΔH2 / ΔH1) between the temperature increase rate ΔH1 and the temperature increase rate ΔH2, and this ratio is set to a predetermined value γ. What is necessary is just to determine viscosity compared with. Further, the degree of viscosity may be another value that can determine the viscosity. As the predetermined value α, for example, a value at which the viscosity of the food to be cooked is 2 × 10 ¹ [mPa · s] (viscosity about soy sauce) is set by experiment or the like.

  On the other hand, when the viscosity determining unit 12 determines that the degree of viscosity is less than the predetermined value α (Yes in S104), that is, when determining that the viscosity of the object to be cooked is low, the control unit 7 stops the second heating coil 4. (S110). Thereby, convection promotion heating is performed. The state of the to-be-cooked object 9 in the to-be-heated object 8 when performing convection acceleration heating in FIG. 4 is shown. The to-be-cooked object 9 on the first heating coil 3 is heated and expanded by the first heating coil 3 so that the density is reduced. Therefore, a relatively lighter and higher flow is generated. On the other hand, the cooking object 9 on the second heating coil 4 has a lower temperature than the cooking object 9 on the first heating coil 3 because the second heating coil 4 is stopped. It becomes easy to generate a flow in which the cooking object 9 raised in the heating coil 3 part is cooled by being touched by air and becomes relatively heavy and descends. Thereby, a convection arises in the to-be-cooked thing 9. FIG.

  FIG. 5A is a diagram showing an example of the power supplied to the heating coils 3 and 4 and the temperature change of the article 8 to be heated in the operation of the induction heating cooker described above. FIG. 5A shows an example in which the power supply amount is halved by supplying power intermittently in step S106. The horizontal axis is the heating time T. A solid line H1 indicates a temperature change of the article 8 to be heated due to the heating of the first heating coil 3 measured by the first temperature measuring unit 10, and a one-dot broken line H2 is a second temperature measured by the second temperature measuring unit 11. The temperature change of the article 8 to be heated due to heating of the heating coil 4 is shown, the solid line 201 shows the power supplied to the first heating coil 3, and the one-dot broken line 202 shows the power supplied to the second heating coil 4. Show. At the temperature on the vertical axis, the scale interval is a predetermined value β.

  In FIG. 5A (a), the temperature of the object to be cooked 9 decreases as the temperature rises as the temperature rises, such as curry, and the first heating coil 3 and the second heating coil 8 change. The operation of the heating coil 4 is shown. The first temperature measurement unit 10 and the second temperature measurement unit 11 are heated by the first heating coil 3 and the second heating coil 4 at predetermined intervals after the start of heating, respectively. The temperature of the heated object 8 is measured, and the measured temperature is output to the control unit 7 and the viscosity determination unit 12.

At time T0, the temperature H1 by the first heating coil 3 and the temperature H2 by the second heating coil 4
Are both temperatures Ha. Accordingly, the reference temperature Hx becomes temperature Ha + predetermined value β (= temperature Hb) (S101). The controller 7 supplies a predetermined amount of constant power to the first heating coil 3 and the second heating coil 4 (S102). Since the heating power of the first heating coil 3 is larger than the heating power of the second heating coil 4, the temperature increase rate ΔH1 is larger than the temperature increase rate ΔH2. That is, the slope of the solid line H1 is larger than the slope of the one-dot broken line H2. Since the difference between the temperature increase rate ΔH1 and the temperature increase rate ΔH2, which is the degree of viscosity, is equal to or greater than the predetermined value α (No in S104), uniform heating is performed.

  When the temperature H1 becomes the reference temperature Hx (temperature Hb) at the time T1 (Yes in S105), the control unit 7 sets the power supply time per unit time to the first heating coil 3 from the time T0. Electric power is supplied at half the supply time of power per unit time up to time T1 (S106). That is, PWM control is performed with a duty ratio of 50%. The amount of power per unit time supplied to the first heating coil 3 is ½ of the amount of power per unit time from time T0 to time T1. By performing this control, it is possible to input an arbitrary amount of electric power for maintaining the same temperature without increasing the temperature, so that the temperature increase rate ΔH1 can be set to zero.

  When the temperature H2 reaches the reference temperature Hx (temperature Hb) at time T2 (Yes in S107), that is, when the temperature H2 catches up to the temperature H1, the control unit 7 has a predetermined magnitude with respect to the first heating coil 3. Control returns to supplying constant power (S108). Thereafter, uniform heating is repeated in the same manner. The reference temperature Hx is temperature Hb + predetermined value β (= temperature Hc) from time T2 to time T4, and is temperature Hc + predetermined value β (= temperature Hd) from time T4 to time T6. As the difference between the temperature increase rate ΔH1 and the temperature increase rate ΔH2 becomes smaller (as the viscosity of the object 9 becomes lower), the period of intermittently supplying power becomes gradually shorter. After time T6, the difference between the temperature increase rate ΔH1 and the temperature increase rate ΔH2, which is the degree of viscosity, is less than a predetermined value α (the temperature increase rate ΔH1 and the temperature increase rate ΔH2 are substantially the same) (Yes in S104), and the control unit 7 Stops the second heating coil 4 and performs convection promoting heating (S110).

  In this way, in a state where the viscosity is lowered, heat transfer by convection becomes dominant, and therefore, the temperature rise due to power input is made uniform by circulating the food to be cooked in accordance with convection. Therefore, it becomes difficult to cause scorching of the food to be cooked due to local heat transfer. Therefore, heating power larger than that used when the viscosity is high may be input to further promote boiling and convection.

  FIG. 5A (b) shows the temperature change of the object to be heated 8 and the operation of the first heating coil 3 and the second heating coil 4 in the case of the object to be cooked 9 having a high viscosity regardless of the temperature, such as a hot cake. Show. The time from the start of heating to time T2 is the same as FIG. 5A (a). The uniform heating is similarly repeated after time T2.

As described above, the induction cooking device of the present embodiment determines the viscosity based on the degree of viscosity, and when the viscosity of the cooking object in the heated object is high, the temperature of the heated object becomes uniform. When the two cooking coils are operated and the viscosity of the cooking object in the object to be heated is low, by operating only the first heating coil, uniform heating is performed when the cooking object has a high viscosity, When the viscosity of the cooking object is low, convection promotion heating can be performed. Thereby, for example, in a solid or high-viscosity material such as a hot cake or a fried egg, there is no heating unevenness, and a uniform baking color can be given without moving on the object to be heated. Moreover, even if the viscosity changes with temperature, such as curry or corn soup, the heating can be controlled according to the viscosity. When the temperature of the food to be cooked is low and the viscosity is high, uniform heating is performed so that the bottom of the pan is not burnt.When the temperature of the food to be cooked rises and the viscosity is low, convection promotion heating is performed to generate convection and heat is generated. Make it easy to get around. Thereby, the effort which moves a to-be-cooked item during a cooking or stirring can be decreased, and the failure of cooking can be reduced.

In the present embodiment, the predetermined value β is the scale interval of the temperature (vertical axis) in FIG. 5A and is a constant value, but this value is decreased when the temperature is low and increased when the temperature is high. Also good.
Moreover, you may determine the predetermined value (beta) with a cooking method.

In this embodiment, in order to simplify the description of the duty control, the duty control power at the time of uniform heating is described as ½ power with a duty ratio of 50%, but the purpose of the duty control at this time is This is to supply electric power for maintaining the same temperature without increasing the temperature, and the duty ratio is not limited to 50%.
[Modification]
In this embodiment, the amount of power supplied per unit time is adjusted by duty-controlling the power supplied to the first heating coil 3, but as shown in FIG. The amount of power supplied per unit time may be adjusted by controlling the amplitude (magnitude) of power supplied to the heating coil 3. In the flowchart of FIG. 3, in step S106, the control unit 7 supplies power having a magnitude that is ½ of the amplitude (magnitude) of power from time T0 (FIG. 5B) to time T1 (FIG. 5B). Thus, the amount of power per unit time supplied to the first heating coil 3 is ½ of the amount of power per unit time from time T0 to time T1. Thereby, since the on / off operation is not repeated, the heat loss is small and the equipment noise is also small.
Embodiment 2
[Configuration of induction heating cooker]
This embodiment demonstrates the induction heating cooking appliance which heats one to-be-heated object with the some heating coil which is not arrange | positioned concentrically. A specific example is shown in FIG. FIG. 6 is a top view of the top plate of the induction heating cooker according to the second embodiment of the present invention. The third heating coil 13, the fourth heating coil 14, the fifth heating coil 15, and the sixth heating coil 16 have the same diameter and are provided around the seventh heating coil 17 at equal intervals. . As shown in FIG. 6, the object to be heated 8 is placed so that the center of the object to be heated 8 comes to the center of the seventh heating coil 17. Thereby, the 3rd-6th heating coils 13, 14, 15, 16 of this embodiment respond | correspond to the 1st heating coil 3 of Embodiment 1, and the 7th heating coil 17 of this embodiment is Embodiment. This corresponds to one second heating coil 14. The first temperature measuring unit 10 is provided on the third heating coil 13, measures the temperature of the object 8 heated by the third heating coil 13, and the second temperature measuring unit 11 The temperature of the object to be heated 8 provided on the seventh heating coil 17 and heated by the seventh heating coil 17 is measured. Since the configuration of the induction heating cooker according to the present embodiment is the same as that of the first embodiment except for the above, the description thereof is omitted.
[Operation of induction heating cooker]
FIG. 7 shows a flowchart of operation control of the heating coils 13 to 17 by the induction heating cooker according to the second embodiment of the present invention. When heating is started, the control unit 7 sets an initial value (temperature H1 + predetermined value β) as the reference temperature Hx (S101). The predetermined value β is, for example, 10 ° C. The controller 7 supplies a predetermined amount of constant power to the third to seventh heating coils 13, 14, 15, 16, and 17 (S102A). That is, PWM control is performed with a duty ratio of 100%. The electric power supplied here is determined by the magnitude of the thermal power input by the user and the cooking method. Thereafter, the viscosity determination unit 12 determines whether the viscosity is high or low. Specifically, the viscosity determination unit 12 obtains the temperature increase rates ΔH1 and ΔH2 based on the temporal change in temperature measured by the first temperature measurement unit 10 and the second temperature measurement unit 11 (S103). Next, the viscosity determination unit 12 obtains the difference (ΔH1−ΔH2) between the temperature increase rate ΔH1 and the temperature increase rate ΔH2 as the degree of viscosity, and determines whether the degree of viscosity is less than a predetermined value α (S104). The predetermined value α is a value by which it can be determined that the temperature increase rate ΔH1 and the temperature increase rate ΔH2 are substantially the same. When the degree of viscosity is less than the predetermined value α, the viscosity determination unit 12 determines that the viscosity of the object to be cooked is “low”, and when the degree of viscosity is equal to or greater than the predetermined value α, the viscosity of the object to be cooked is “high”. Judge.

  When it is determined that the viscosity of the cooking object is high (No in S104), the control unit 7 waits until the temperature H1 becomes equal to or higher than the reference temperature Hx (S105). When the control unit 7 determines that the temperature H1 has become equal to or higher than the reference temperature Hx, the power is intermittently supplied to the third to sixth heating coils 13, 14, 15, 16 per unit time. Electric power is supplied so that the electric energy is ½ of the electric energy per unit time supplied to the first heating coil 3 in step S101 (S106A). That is, PWM control is performed with a duty ratio of 50%. Next, the control unit 7 waits until the temperature H2 becomes equal to or higher than the reference temperature Hx (S107). When the controller 7 determines that the temperature H2 has become equal to or higher than the reference temperature Hx, a predetermined amount of constant power is supplied to the third to sixth heating coils 13, 14, 15, 16 (S108A). A predetermined value β is added to the reference temperature Hx (S109), and the process returns to step S103.

In steps S105 to S108A, the temperature of the heated object 8 heated by the third to sixth heating coils 13, 14, 15, 16 and the temperature of the heated object 8 heated by the seventh heating coil 17 are as follows. The uniform heating is controlled so as to be uniform, that is, so that the temperature difference at the bottom of the article to be heated 8 becomes small. In step S106A, electric power that is ½ of the amount of electric power supplied to the third to sixth heating coils 13, 14, 15, and 16 in step S101A is supplied. It is only necessary to be able to control the temperature increase rate ΔH1 by the heating coils 13, 14, 15, and 16 to be almost zero, and the power supply is not limited to a value of 1/2, and the supplied power may be duty-controlled. In this embodiment, the degree of viscosity is the difference between the temperature increase rate ΔH1 and the temperature increase rate ΔH2, but it may be the ratio (ΔH2 / ΔH1) between the temperature increase rate ΔH1 and the temperature increase rate ΔH2, and this ratio is set to a predetermined value γ. What is necessary is just to determine viscosity compared with. Further, the degree of viscosity may be another value that can determine the viscosity. As the predetermined value α, for example, a value at which the viscosity of the food to be cooked is 2 × 10 ¹ [mPa · s] (viscosity about soy sauce) is set by experiment or the like.

  On the other hand, when the viscosity determining unit 12 determines that the degree of viscosity is less than the predetermined value α (Yes in S104), that is, when determining that the viscosity of the object to be cooked is low, the control unit 7 stops the seventh heating coil 17. (S110A). Thereby, convection promotion heating is performed.

  FIG. 8 is a diagram showing an example of the power supplied to the heating coils 13, 14, 15, 16, and 17 and the temperature change of the object to be heated 8 in the operation of the induction heating cooker described above. The horizontal axis is the heating time T. A solid line H1 indicates a temperature change of the article 8 to be heated due to heating of the third to sixth heating coils 13, 14, 15, 16 measured by the first temperature measuring unit 10, and a one-dot broken line H2 indicates a second temperature. The temperature change of the to-be-heated object 8 by the heating of the 7th heating coil 17 measured by the measurement part 11 is shown, and the continuous line 203 shows the electric power supplied to the 3rd-6th heating coils 13,14,15,16. The dashed line 204 indicates the power supplied to the seventh heating coil 17. At the temperature on the vertical axis, the scale interval is a predetermined value β.

  FIG. 8 (a) shows the temperature change of the object to be cooked 9 and the third to seventh heating coils 13, in the case of the object to be cooked 9 in which the viscosity of the object to be cooked 9 decreases as the temperature rises, such as curry. Operations of 14, 15, 16, and 17 are shown. The first temperature measurement unit 10 and the second temperature measurement unit 11 are heated by the third to sixth heating coils 13, 14, 15, and 16, respectively, at predetermined time intervals after the start of heating. Then, the temperature of the heated object 8 heated by the seventh heating coil 17 is measured, and the measured temperature is output to the control unit 7 and the viscosity determining unit 12.

At time T0, the temperature H1 due to the third to sixth heating coils 13, 14, 15, 16 and the temperature H2 due to the seventh heating coil 17 are both the temperature Ha. Accordingly, the reference temperature Hx becomes temperature Ha + predetermined value β (= temperature Hb) (S101). The controller 7 supplies a predetermined amount of constant power to the third to seventh heating coils 13, 14, 15, 16, and 17 (S102A). Since the total heating power of the third to sixth heating coils 13, 14, 15, 16 is larger than the heating power of the seventh heating coil 17, the temperature increase rate ΔH1 is larger than the temperature increase rate ΔH2. That is, the slope of the solid line H1 is larger than the slope of the one-dot broken line H2. Since the difference between the temperature increase rate ΔH1 and the temperature increase rate ΔH2, which is the degree of viscosity, is equal to or greater than the predetermined value α (No in S104), uniform heating is performed.

  When the temperature H1 becomes the reference temperature Hx (temperature Hb) at time T1 (Yes in S105), the control unit 7 applies the unit 3 to the sixth to sixth heating coils 13, 14, 15, and 16 per unit time. The power is supplied by setting the power supply time to ½ of the power supply time per unit time from time T0 to time T1 (S106A). That is, PWM control is performed with a duty ratio of 50%. The amount of power per unit time supplied to the third to sixth heating coils 13, 14, 15, 16 is ½ of the amount of power per unit time from time T0 to time T1. By performing this control, it is possible to input an arbitrary amount of electric power for maintaining the same temperature without increasing the temperature, so that the temperature increase rate ΔH1 can be set to zero.

  When the temperature H2 becomes the reference temperature Hx (temperature Hb) at time T2 (Yes in S107), that is, when the temperature H1 and the temperature H2 become the same, the control unit 7 controls the third to sixth heating coils 13, 14, 15 , 16 is returned to control for supplying a predetermined amount of constant power (S108A). Thereafter, uniform heating is repeated in the same manner. The reference temperature Hx is temperature Hb + predetermined value β (= temperature Hc) from time T2 to time T4, and is temperature Hc + predetermined value β (= temperature Hd) from time T4 to time T6. As the difference between the temperature increase rate ΔH1 and the temperature increase rate ΔH2 becomes smaller (as the viscosity of the object 9 becomes lower), the period of intermittently supplying power becomes gradually shorter. After time T6, the difference between the temperature increase rate ΔH1 and the temperature increase rate ΔH2, which is the degree of viscosity, is less than a predetermined value α (the temperature increase rate ΔH1 and the temperature increase rate ΔH2 are substantially the same) (Yes in S104), and the control unit 7 Stops the seventh heating coil 17 and performs convection promoting heating (S110).

  In this way, in a state where the viscosity is lowered, heat transfer by convection becomes dominant, and therefore, the temperature rise due to power input is made uniform by circulating the food to be cooked in accordance with convection. Therefore, it becomes difficult to cause scorching of the food to be cooked due to local heat transfer. Therefore, heating power larger than that used when the viscosity is high may be input to further promote boiling and convection.

  FIG. 8B shows the temperature change of the article 8 to be cooked and the third to seventh heating coils 13, 14, 15, 16, etc. 17 operations are shown. The time from the start of heating to time T2 is the same as FIG. The uniform heating is similarly repeated after time T2.

As described above, also in the induction heating cooker of this embodiment, the viscosity is determined based on the degree of viscosity, and when the viscosity of the cooking object in the heated object is high, the temperature of the heated object is uniform. When all the heating coils are operated so that the viscosity of the cooking object in the heated object is low, the viscosity of the cooking object in the heated object is operated by operating the third to sixth heating coils. When the temperature is high, uniform heating can be performed, and when the viscosity of the cooking object in the heating object is low, convection promotion heating can be performed. Thereby, for example, in a solid or high-viscosity material such as a hot cake or a fried egg, there is no heating unevenness, and a uniform baking color can be given without moving on the object to be heated. Moreover, even if the viscosity changes with temperature, such as curry or corn soup, the heating can be controlled according to the viscosity. When the temperature of the food to be cooked is low and the viscosity is high, uniform heating is performed so that the bottom of the pan is not burnt.When the temperature of the food to be cooked rises and the viscosity is low, convection promotion heating is performed to generate convection and Make it easy to get around. Thereby, the effort which moves a to-be-cooked item during a cooking or stirring can be decreased, and the failure of cooking can be reduced.

  In the present embodiment, the predetermined value β is the scale interval of the temperature (vertical axis) in FIG. 8 and is a constant value, but this value is decreased when the temperature is low and increased when the temperature is high. Also good. Moreover, you may determine the predetermined value (beta) with a cooking method.

  In the present embodiment, in step S106A, the power supply is intermittently supplied to the third to sixth heating coils 03, 04, 05, and 16 so that the amount of supplied power is halved. However, the amount of supplied power may be halved by changing the amplitude (magnitude) of the power.

In this embodiment, in order to simplify the description of the duty control, the duty control power at the time of uniform heating is described as ½ power with a duty ratio of 50%, but the purpose of the duty control at this time is This is to supply electric power for maintaining the same temperature without increasing the temperature, and the duty ratio is not limited to 50%.
Embodiment 3
In the induction heating cooker of Embodiment 3 of the present invention, as shown in FIG. 9, the induction heating cooker of Embodiment 1 further stores a temperature range in which physical properties of the cooking object change and stores the temperature range. A temperature range management unit 18 for issuing a temperature control instruction is provided.

  The temperature range stored by the temperature range management unit is, for example, a temperature range where a general protein is denatured (around 60 degrees), a temperature where cellulose is decomposed (around 90 degrees), or a management temperature range when heating meat ( 80 to 90 degrees). FIG. 10 shows the temperature change when the temperature is raised using the temperature range management unit 18. Since the temperature range management unit 18 does not issue an instruction outside the control temperature range, the temperature is increased at a predetermined β (for example, in increments of 5 degrees) as in FIG. 5A, and the control temperature range is seen in the control temperature range of FIG. As described above, the temperature is increased by setting the predetermined value β to a small value (for example, in increments of 1 degree). As described above, by controlling finely so as to increase the uniformity in the temperature range in the change in the physical property managed by the temperature range management unit, the change in the physical property at the change point can be made to proceed in the same manner. Therefore, cooking can be performed while changing the physical properties of the object to be cooked uniformly, so that the quality of cooking can be improved.

Moreover, you may provide the temperature range management part 18 in the induction heating cooking appliance of Embodiment 2 further. FIG. 11 shows a temperature change when the temperature is raised using the temperature range management unit 18 in that case. Since the temperature range management unit 18 does not give an instruction outside the control temperature range, the temperature is increased at a predetermined β (for example, in increments of 5 degrees) similar to FIG. 5A, and the control temperature range is seen in the control temperature range of FIG. As described above, the temperature is increased by setting the predetermined value β to a small value (for example, in steps of 1 degree). As described above, by controlling finely so as to increase the uniformity in the temperature range in the change in the physical property managed by the temperature range management unit, the change in the physical property at the change point can be made to proceed in the same manner. Therefore, cooking can be performed while changing the physical properties of the object to be cooked uniformly, so that the quality of cooking can be improved.
Embodiment 4
In the induction heating cooker according to the fourth embodiment of the present invention, a menu selection unit 19 may be provided in the induction heating cooker according to the third embodiment as shown in FIG. When the user operates the menu selection unit 19 and selects a cooking menu, only when the temperature range management unit 18 stores the physical properties corresponding to this menu, the predetermined types as shown in FIGS. The temperature is increased with a small value β. With this operation, fine temperature control can be performed only when necessary.

  The induction heating cooker according to the present invention has an effect that uniform heating and convection promotion heating can be performed in accordance with the viscosity of the cooking object in the heating object, and the induction heating cooking apparatus used in general homes and the like. Useful for.

The block diagram of the induction heating cooking appliance by Embodiment 1 of this invention The figure which shows the state of the to-be-cooked object in a to-be-heated material when operating both the 1st heating coil and the 2nd heating coil. The flowchart of operation control of the heating coils 3 and 4 by the induction heating cooking appliance of Embodiment 1 of this invention. The figure which shows the state of the to-be-cooked object in a to-be-heated object when performing convection promotion heating The figure which showed the example of the power change to the heating coils 3 and 4 in the operation | movement of the induction heating cooking appliance of FIG. 3, and the temperature change of a to-be-heated material The figure which showed the example of the electric power supplied to the heating coils 3 and 4 in the operation | movement of the modification of the induction heating cooking appliance of FIG. 3, and the temperature change of to-be-heated material The top view of the top plate of the induction heating cooking appliance by Embodiment 2 of the present invention The flowchart of operation control of the heating coils 13-17 by the induction heating cooking appliance of Embodiment 2 of this invention. The figure which showed the example of the electric power supplied to the heating coils 13-17 and the temperature change of a to-be-heated object in operation | movement of the induction heating cooking appliance of FIG. The block diagram of the induction heating cooking appliance by Embodiment 3 of this invention The figure which showed the example of the electric power supplied to the heating coils 3 and 4 and the temperature change of a to-be-heated object at the time of using the temperature range management part in operation | movement of the induction heating cooking appliance by Embodiment 3 of this invention. The figure which showed the example of the electric power supplied to the heating coils 13-17 at the time of using the temperature range management part in operation | movement of the induction heating cooking appliance by Embodiment 3 of this invention, and the temperature change of a to-be-heated material. The block diagram of the induction heating cooking appliance by Embodiment 4 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Induction heating cooker 2 Top plate 3 1st heating coil 4 2nd heating coil 5 1st high frequency electric power supply part 6 2nd high frequency electric power supply part 7 Control part 8 To-be-heated object 9 To-be-cooked object 10 1st Temperature measurement unit 11 second temperature measurement unit 12 viscosity determination unit 13 third heating coil 14 fourth heating coil 15 fifth heating coil 16 sixth heating coil 17 seventh heating coil 18 temperature range management unit 19 Menu selection section

Claims (5)

A top plate on which an object to be heated is placed, a first heating coil and a second heating coil provided below the top plate, and a first high frequency that supplies high frequency power to the first heating coil A power supply unit, a second high-frequency power supply unit that supplies high-frequency power to the second heating coil, and a first unit that is provided in the vicinity of the first heating coil and measures the temperature of the object to be heated. A temperature measuring unit, a second temperature measuring unit provided in the vicinity of the second heating coil and measuring the temperature of the object to be heated; and the object to be heated measured by the first temperature measuring unit. A viscosity determining unit that determines that the viscosity of the heated object is high when a difference between the temperature and the temperature of the heated object measured by the second temperature measuring unit differs by a predetermined value or more within a predetermined time; and Viscosity judgment part has high viscosity of the heated object If it is determined, the first or first temperature until the temperature of the heated object measured by the first temperature measuring unit and the temperature of the heated object measured by the second temperature measuring unit become substantially the same. An induction heating cooker comprising: a control unit that controls the first and second high-frequency power supply units so as to reduce the output power of the two heating coils. When the temperature of the heated object measured by the first temperature measuring unit and the temperature of the heated object measured by the second temperature measuring unit are substantially the same, the control unit decreases the temperature of the heated object. The induction heating cooker of Claim 1 which controls the said 1st and 2nd high frequency electric power supply part so that the output electric power of a 1st or 2nd heating coil may be increased. The viscosity determination unit has a predetermined difference within a predetermined time between a temperature of the heated object measured by the first temperature measuring unit and a temperature of the heated object measured by the second temperature measuring unit. When the difference is not more than the value, it is determined that the viscosity of the object to be heated is low, and the control unit determines that the viscosity of the object to be heated is low when the viscosity determination unit determines that the viscosity of the object to be heated is low. The induction heating cooker of Claim 1 which controls the said 1st and 2nd high frequency electric power supply part so that the heating coil which did not reduce output electric power among heating coils may be stopped. The induction heating according to claim 1 or 2, wherein the first heating coil is a heating coil arranged concentrically with the second heating coil and having a diameter different from that of the second heating coil. Cooking device. The first heating coil is a plurality of heating coils having a center different from that of the second heating coil and provided around the second heating coil. The induction heating cooker described.

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