JP2014056846A - Induction heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an induction heating cooker which can detect availability of temperature detection without causing abnormally high temperature of a pan.SOLUTION: An induction heating cooker comprises: a plurality of heating coils including a first heating coil arranged at a position closer to a temperature sensor 12 and a second heating coil arranged at a position farther from the temperature sensor 12 than the first heating coil; and a control part 8 which controls power applied to the first heating coil higher than that of the second heating coil after receiving an instruction of a preheating operation from an operation part 5 to preheat the heated object to a preset temperature, and controls, during the preheating operation, a total amount of power applied to the second heating coil becomes larger than a total amount of power applied to the first heating coil.

Description

  The present invention relates to an induction heating cooker that drives a plurality of heating coils to heat an object to be heated.

As a conventional induction heating cooker, “the temperature detection element that detects the temperature of the pan, and the temperature and the rate of temperature change of this temperature detection element are detected, and the power is supplied to the heating coil so that the temperature is within a predetermined level range. There is proposed a heating control means that controls the heating coil, and the heating control means stops the power supply to the heating coil when the temperature change rate is higher than a predetermined level (see, for example, Patent Document 1).
On the other hand, “a central coil wound in a planar shape, a plurality of peripheral coils disposed around the central coil, and a plurality of independently supplying a high-frequency current to each of the central coil and the peripheral coil. According to the power supply circuit unit, detection means for detecting a state in which the object to be heated is placed above the central coil and each peripheral coil, and the placement state of the object to be heated detected by the detection means , By providing a “drive control unit that controls the power supply circuit unit so that a high-frequency current is selectively supplied to each of the central coil and the peripheral coil”, “when the pan has various sizes and shapes, Even if the pan is placed out of the center, it has been proposed that it is efficiently heated according to the placement state of the object to be heated (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 62-126586 (Claim 1) WO 2010/101202 (page 3 to page 7, FIG. 3)

  According to the induction heating cooker described in Patent Document 1, the power supplied to the heating coil can be controlled based on the temperature of the pan (hereinafter referred to as an object to be heated) and the temperature change rate. In addition, according to the induction heating cooker described in Patent Document 2, a heated body (hereinafter, referred to as a heated object) having various sizes and shapes can be used. In the induction heating cooker as in Patent Document 2, when the control described in Patent Document 1 is to be performed, a heating coil that is distant from the temperature detecting means is driven to heat an object to be heated depending on conditions. There is. Under such conditions, if a warped pan having a part warped as a heated object is used, and the heating operation is carried out by placing the warped part above the temperature detecting means, temperature detection is performed. The temperature rise in the part detected by the means becomes slower than the temperature rise in the other parts. When the control method described in Patent Document 1 is used under such conditions, when the temperature detection element detects that the object to be heated is at a predetermined level, the portions other than the portion detected by the temperature detection means are predetermined. There was a problem of rising to an abnormally high temperature higher than the level. When the object to be heated is heated to an abnormally high temperature in this way, there is a problem that the portion is deformed or the fluorine coating the surface is peeled off.

  The present invention has been made in order to solve the above-described problems, and even in an induction heating cooker that heats a heated object using a plurality of heating coils as described above, the abnormally high temperature of the heated object It is possible to obtain an induction heating cooker that can reliably detect.

  An induction heating cooker according to the present invention includes a top plate on which an object to be heated is placed, a plurality of heating coils disposed below the top plate, and a drive unit that inputs high-frequency power to the plurality of heating coils. Depending on the power state when high-frequency power is applied to each heating coil, a temperature detector that is disposed below the top plate and detects infrared rays emitted from the object to be heated to detect the temperature of the object to be heated , A load detection unit that detects whether or not an object to be heated is on the top plate above each heating coil, an operation unit that receives instructions from the user to start or stop heating, and an instruction from the operation unit A control unit that controls the amount of electric power that is input from the drive unit to the heating coil, and the control unit selects a heating coil group that is determined by the load detection unit to be heated on the top plate above the heating coil group. A first heating coil that is substantially the center of the object to be heated, and a periphery of the first heating coil. The heating coil group that is set to the second heating coil and is determined to have no object to be heated is set as the third heating coil, and the total amount of power input to the second heating coil during the preheating operation is the first heating coil. Control is made so that it is greater than the total amount of power input to the coil.

  By configuring the induction heating cooker according to the present invention as described above, the load detection unit specifies where the heated object is disposed in the plurality of heating coils, and the temperature detection unit detects the heated unit. Therefore, the temperature of the object to be heated can be reliably detected and efficiently heated regardless of the placement position of the object to be heated on the top plate as compared with the conventional case.

It is a disassembled perspective view of the induction heating cooking appliance which concerns on Embodiment 1 of this invention. It is a top view of the induction heating cooking appliance which concerns on Embodiment 1 of this invention. It is the schematic of the induction heating cooking appliance in the state by which the to-be-heated material was mounted in the center of the heating part which concerns on Embodiment 1 of this invention. It is a functional block diagram of the principal part of the induction heating cooking appliance which concerns on Embodiment 1 of this invention. It is the schematic of the induction heating cooking appliance in the state which shifted from the center of the heating part which concerns on Embodiment 1 of this invention, and the to-be-heated material was mounted. It is a disassembled perspective view which is a modification of arrangement | positioning of the heating coil of the induction heating cooking appliance which concerns on Embodiment 1 of this invention. It is an operation part enlarged view of the induction heating cooking appliance which concerns on Embodiment 1 of this invention. It is a heating flow of the preheating mode which concerns on Embodiment 1 of this invention. It is an input electric power figure to each heating coil at the time of the preheating mode which concerns on Embodiment 1 of this invention. It is a figure which shows the temperature of the to-be-heated material at the time of the preheating mode which concerns on Embodiment 1 of this invention. It is a functional block diagram of the principal part of the induction heating cooking appliance in the state in which the curvature pan concerning Embodiment 1 of this invention was mounted.

Embodiment 1 FIG.
In the first embodiment of the present invention, a case where the present invention is applied to a so-called built-in induction heating cooker installed at an installation opening formed in kitchen furniture will be described as an example.

Hereinafter, the overall configuration of the first embodiment of the present invention will be described with reference to FIGS. 1 and 2.
1 is an exploded perspective view of an induction heating cooker according to Embodiment 1 of the present invention, and FIG. 2 is a top view of the induction heating cooker according to Embodiment 1 of the present invention. In FIG. 1, FIG. 2, and each figure described later, the same reference numerals are the same or equivalent, and are common throughout the specification.

As shown in FIGS. 1 and 2, a top plate 2 on which an object to be heated 100 such as a pan is placed is provided on the upper surface side of the main body 1 of the induction heating cooker. The top plate 2 has three heating ports, a first heating port 3a on the left side of the front side of the main body 1, a second heating port 3b on the right side of the front side of the main body 1, and a third heating port 3c in the approximate center of the back side of the main body 1. 3 is printed, and three heating units 4 are provided below the top plate 2 of each heating port 3; a first heating unit 4a, a second heating unit 4b, and a third heating unit 4c. . The heating port 3 formed in the top plate 2 indicates a range that can be heated by the heating unit 4 corresponding to each heating port 3, and the user uses the heating port 3 as a mark to place the object to be heated 100 on the top plate. 2 is mounted.
The top plate 2 is composed of a heat-resistant glass 2a that transmits infrared rays and a frame 2b that surrounds the glass 2a. Between the top opening end 1a of the main body 1 and the top plate 2, a rubber packing or the like is used. A sealing material is provided, and the top plate 2 is pressed against the main body 1 with screws or the like so that water does not enter between the top plate 2 and the main body 1. In addition, the heating port 3 described on the surface of the top plate 2 is formed by applying or printing a coating on the surface of the glass 2a.
In the first embodiment, the glass 2a is used for the top plate 2. However, the glass 2a is not limited to this, and it has heat resistance, a low coefficient of thermal expansion, and transmits infrared rays and magnetic flux. Any material can be used. Also, there are various types of glass 2a such as heat-resistant tempered glass and crystallized glass, but any glass having the above characteristics may be used.
Moreover, you may make it comprise the top plate 2 only with the glass 2a, without using the flame | frame 2b, for example.

An operation unit 5 corresponding to each heating unit 4 is provided in the frame 2b portion on the front side of the main body 1 of the top plate 2, and the heating power and cooking menu when the object 100 is heated by the operation unit 5 are provided. Can be set. The first heating unit 4a can be operated by the operating unit 5a, the second heating unit 4b can be operated by the operating unit 5b, and the third heating unit 4c can be operated by the operating unit 5c.
In the vicinity of the operation unit 5, a display unit 6 is provided for displaying the operation state of each heating unit 4, the input / operation content from the operation unit 5, and the like. The display unit 6a corresponds to the first heating unit 4a, the display unit 6b corresponds to the second heating unit 4b, and the display unit 6c corresponds to the third heating unit 4c.
In this way, the induction heating cooker places the object to be heated 100 on the heating port 3, and instructs the operation of the heating unit 4 by the operation unit 5 corresponding to the mounted heating port 3, The heated object 100 is heated by the driven heating unit 4.

  Next, each heating unit 4 includes a plurality of heating coils. The driving unit 7 supplies high-frequency power to each heating coil in the main body 1 and receives an instruction from the operation unit 5. A control unit 8 is provided for controlling the above. When high-frequency power is input from the drive unit 7 to the heating coil, a magnetic field is generated around the heating coil, and the magnetic flux passes through the top plate 2 and reaches the object to be heated 100 placed on the top plate 2. The magnetic flux heats the object to be heated 100 as it flows. In addition, since the specific structure of the heating part 4 and a heating coil is demonstrated later, description of a specific structure is abbreviate | omitted here.

As shown in FIGS. 1 and 2, the frame 2 b on the back side of the top plate 2 communicates with the inside of the main body 1, and an intake port 2 c for taking outside air as cooling air into the main body 1. An exhaust port 2d for discharging the air taken into the main body 1 to the outside is formed. Also, a fan 9 is provided inside the main body 1, and by driving the fan 9, external air is taken into the main body 1 from the air inlet 2 c, and the air passes through the fan 9 and then passes through the fan 9. Various electrical components such as the drive unit 7 and the control unit 8 and the heating coil are cooled and discharged to the outside of the main body 1 through the exhaust port 2d.
In the first embodiment, an example in which the air inlet 2c and the air outlet 2d are formed on the top plate 2 is shown. However, the present invention is not limited to this. Or an exhaust port may be formed.

Next, a specific configuration of the heating unit 4 will be described with reference to FIGS.
3 is a schematic diagram of an induction heating cooker in a state where an object to be heated is placed in the center of the heating unit according to Embodiment 1 of the present invention, and FIG. 4 is induction heating cooking according to Embodiment 1 of the present invention. FIG. 5 is a schematic diagram of the induction heating cooker in a state where an object to be heated is placed at a position shifted from the center of the heating unit according to Embodiment 1 of the present invention.

  As shown in FIG. 3, the heating unit 4 includes a central coil 10 that is a heating coil disposed substantially at the center of the heating port 3 and a plurality of peripheral coils 11 that are heating coils disposed around the central coil 10. Configured.

The center coil 10 has a circular planar shape, and is formed by winding a conductive wire made of an arbitrary metal with an insulating coating in the circumferential direction. The central coil 10 is composed of an inner central coil 10a having a small diameter and an outer central coil 10b having a larger diameter than the inner central coil 10a. An annular gap is provided between the inner central coil 10a and the outer central coil 10b. Further, the inner central coil 10 a and the outer central coil 10 b are connected in series and are driven by a single drive unit 7.
In the first embodiment, the inner central coil 10a and the outer central coil 10b are configured to be driven by a single driving unit 7. However, these are driven using independent driving units 7, respectively. May be.

In the gap between the inner central coil 10a and the outer central coil 10b described above, a plurality of temperature sensors 12 serving as temperature detection units are arranged. Two types of temperature sensors 12 are arranged, a contact temperature sensor 12a and a non-contact temperature sensor 12b. The contact-type temperature sensor 12 a is disposed so as to contact the lower surface of the top plate 2, and indirectly detects the temperature of the object to be heated 100 placed on the top plate 2 by measuring the temperature of the top plate 2. Is. On the other hand, the non-contact temperature sensor 12b is disposed below the top plate 2, and the heated object 100 placed on the top plate 2 is measured by measuring the amount of infrared rays emitted from the heated object 100 and transmitted through the top plate 2. The temperature is detected directly. It should be noted that the top plate 2 above the non-contact temperature sensor 12b may be formed with a “window” that allows infrared rays to pass through more easily than other top plate 2 portions. The “window” is formed by, for example, applying a portion other than the window portion with a paint that hardly transmits infrared rays, or is formed using another material that easily transmits infrared rays instead of the glass 2a.
The arrangement of the temperature sensor 12 described above is an example, and the arrangement is not limited to this arrangement, and the temperature sensor 12 may be arranged in the vicinity of the central coil 10. Moreover, the number is not limited to this.

Next, characteristics due to differences in detection method of the temperature sensor 12 will be described.
Since the contact-type temperature sensor 12a indirectly measures the temperature of the object to be heated 100 via the top plate 2, when the object to be heated 100 is heated and the temperature rises, the actual object to be heated 100 is heated. It has a feature that a detection result lower than the temperature is obtained. On the other hand, since the non-contact temperature sensor 12b directly measures the amount of infrared rays emitted from the object to be heated 100, the actual object to be heated 100 is also heated when the object to be heated 100 is heated. A detection result substantially equivalent to the temperature of can be obtained. However, the object to be heated 100 is characterized in that the reflectance varies depending on the surface condition of the bottom surface. When the reflectance on the bottom surface of the object to be heated 100 varies, the amount of infrared rays emitted from the object to be heated 100 varies. Thereby, the non-contact temperature sensor 12b has a feature that an error occurs in the measurement result when the surface condition of the bottom surface of the article to be heated 100 changes. Note that the contact-type temperature sensor 12a measures indirectly, so that the measurement result does not change depending on the surface condition of the bottom surface of the article to be heated 100.
Therefore, in the first embodiment, the temperature detection accuracy of the object to be heated 100 is improved by effectively utilizing the difference in the characteristics of the temperature sensor 12 as described above. However, in the case of what is called a “warp pan” in which the bottom surface of the object to be heated 100 is warped, the object to be heated 100 is warped even when a plurality of temperature sensors having different methods are combined as described above. If the part is placed so as to be above the temperature sensor 12, there is a problem that measurement cannot be performed with high accuracy.

Next, the peripheral coil 11 disposed around the central coil 10 will be described.
As shown in FIG. 3, the peripheral coil 11 is formed by winding a conductive wire made of an arbitrary metal with an insulating coating in an annular shape having a substantially ¼ arc-shaped planar shape. The arc of the peripheral coil 11 on the side close to the central coil 10 is formed so as to be substantially along the circular outer periphery of the central coil 10 at a predetermined interval, and a predetermined gap is formed between the central coil 10 and the peripheral coil 11. Spacing spaces are formed.

In the first embodiment, four peripheral coils 11 formed as described above are provided around the central coil 10 (each peripheral coil 11 may be distinguished from the peripheral coils 11a, 11b, 11c, and 11d). Is provided. Further, each peripheral coil 11 is arranged outside the central coil 10 so as to substantially follow the circular outer shape of the central coil 10. Each peripheral coil 11 is arranged so as to be shifted by about 90 ° with respect to the central coil 10 and is configured to be driven by an independent driving unit 7.
The peripheral coil 11 may be formed, for example, as an annular coil that is slightly larger than the central coil 10 and arranged concentrically with the central coil 10. Further, the number of the peripheral coils 11 is not limited to four, and may be any number.
In the first embodiment, each peripheral coil 11 is configured to be driven by using an independent driving unit 7, but this is not a limitation, and a plurality of peripheral coils 11 are connected in series. The group of heating coils may be driven by using the independent driving units 7.

Here, in this Embodiment 1, although the several heating coil is provided, the center coil 10 installed in the position close | similar to the temperature sensor 12 which is a temperature detection part is used as the 1st heating coil, This 1st heating coil. The peripheral coil 11 disposed at a position farther from the temperature sensor 12 is set as the second heating coil.
Moreover, since each heating coil is arrange | positioned so that it may adjoin as much as possible, and a heating coil is arrange | positioned under the heating port 3 without a big clearance gap by this, the heating nonuniformity by the presence or absence of the heating coil in the heating port 3 is carried out. Can be suppressed.

FIG. 4 is a functional block diagram of the main part of the induction heating cooker according to Embodiment 1 of the present invention.
As shown in FIG. 4, the heating unit 4 includes a central coil 10 that is a heating coil disposed substantially at the center of the heating port 3, and a plurality of peripheral coils 11 that are heating coils disposed around the central coil 10. The central coil 10, the peripheral coil 11, and the temperature sensor 12 are held by a coil support (not shown).

  The drive unit 7 is configured by an inverter circuit, provided with a drive unit 7 corresponding to each of the central coil 10 and each peripheral coil 11, and each drive unit 7 can be driven independently, and independently. High frequency power can be supplied to each heating coil.

The control unit 8 controls the operation of each of the drive units 7. For example, the control unit 8 receives an instruction from the operation unit 5, and the control unit 8 instructs the drive unit 7 to drive in accordance with the instruction. High-frequency power is supplied from the driving units 7 to the heating coils corresponding to the respective driving units 7, and a current flows through the object to be heated 100 placed on the top 2 by the magnetic field generated by each heating coil. Heated.
Moreover, the control part 8 receives the electrical signal from the temperature sensor 12, and calculates the temperature of the to-be-heated object 100 based on the electrical signal.
Moreover, the control part 8 is connected with the load detection part 13 which detects whether the to-be-heated material 100 is mounted above each heating coil, and demonstrates the load detection part 13 below.

The load detection unit 13 is configured by a detection unit that detects a power state flowing through each heating coil. For example, in the first embodiment, the load detection unit 13 is configured by a current detection unit that detects a current flowing through each heating coil. Has been. From each current value detected by the current detector, the impedance of each heating coil is calculated, and thereby it is determined whether or not the object to be heated 100 is placed on the top plate 2 above each heating coil. . In general, the impedance of the heating coil changes depending on the presence / absence, size (area), and material (magnetism) of the object to be heated 100 placed on the top plate 2 above the heating coil. Therefore, the load detection unit 13 is not only the presence / absence of the object to be heated 100, but also the material of the object to be heated 100 is a magnetic material, a non-magnetic material, or a ferromagnetic material that is a strong magnetic material even with a magnetic material. Etc. can be detected.
In the first embodiment, the load detection unit 13 is configured with a current detection unit that detects the current flowing through each heating coil. However, the impedance is calculated from other power states (voltage, etc.). Yes, it is not limited to this.

As described above, the detection results such as the presence / absence of the object to be heated 100 above each heating coil and the material of the object to be heated 100 detected by the load detection unit 13 are output to the control unit 8. Based on the detection result of the load detection unit 13, the control unit 8 performs control so that power is supplied only to the heating coil in which the object to be heated 100 is placed on the top plate 2 above the heating coil. And it controls so that the electric power to the heating coil in which the to-be-heated material 100 is not mounted on the top plate 2 of the upper side is not supplied. Here, in the first embodiment, when it is determined that the object to be heated 100 is not placed above the central coil 10 or the peripheral coil 11, the heating coil does not supply power. Reset as.
For example, as shown in FIG. 3, the object to be heated 100 is placed above all of the heating coils of the central coil 10 and the peripheral coils 11a, 11b, 11c, and 11d among the plurality of heating coils. In this case, the control unit 8 sets the central coil 10 as the first heating coil, and sets the peripheral coils 11a, 11b, 11c, and 11d as the second heating coil.
On the other hand, in the situation where the object to be heated 100 is placed only above the central coil 10 and the peripheral coils 11a and 11b among the plurality of heating coils as shown in FIG. The coil 10 is set as the first heating coil, the peripheral coils 11a and 11b are set as the second heating coil, and the peripheral coils 11c and 11d are set as the third heating coil.

Next, the modification of arrangement | positioning of the heating coil of the induction heating cooking appliance which concerns on Embodiment 1 of this invention is demonstrated.
In the first embodiment described above, one object 100 is heated by one heating unit 4, but one object 100 is heated by a plurality of heating units 4. It may be configured. For example, as shown in FIG. 6, the heating unit 4 is arranged in a grid pattern below the top plate 2, and the object to be heated 100 is placed across the plurality of heating units 4. The heated object 100 may be heated by driving a plurality of heating units 4 that are detected as the heated object 100 being placed thereon. In this case, one heating unit 4 may be constituted by a plurality of heating coils, or may be constituted by one heating coil. The heating port 3 may display the placement position of the object to be heated 100 estimated from the detection result of the load detection unit 13 using a light source such as an LED provided separately, or heating to which power is input. You may make it display the position of the part 4 or a heating coil. Moreover, you may form the heating port 3 above all the heating parts 4 in order to show that the heating part 4 exists below irrespective of the mounting condition of the to-be-heated material 100. FIG.
In the above configuration, the temperature sensors 12 do not have to be provided in all the heating units 4. In the vertical and horizontal directions, the heating unit 4 provided with the temperature sensor 12 and the heating unit 4 provided with no temperature sensor 12 are provided. May be arranged so as to repeatedly appear. In that case, similarly to the induction heating cooker of the first embodiment described above, the heating coil determined by the load detection unit 13 that the article to be heated 100 is not placed is set as the third heating coil. The heating coil in which the temperature sensor 12 is installed in the vicinity of the heating coil in which it is determined that the article to be heated 100 is placed is set as the first heating coil, and the temperature sensor 12 is installed in the distance. The heating coil that is being used (that is, the heating coil other than the first heating coil among the heating coils that are determined to have the article to be heated 100 placed thereon) is set as the second heating coil.

Next, the operation unit 5 will be described. FIG. 7 is an enlarged view of the operation unit of the induction heating cooker according to Embodiment 1 of the present invention.
As shown in FIG. 7, operation keys 5 d corresponding to the respective heating ports 3 are arranged on the operation unit 5, and keys and dials are provided so that a heating program suitable for cooking that the user wants to perform can be easily recognized. It is prepared. In the first embodiment, a preheating key is provided as a cooking menu. When this preheating key is pressed, the control unit 8 applies appropriate power to the corresponding heating coil in order to preheat the heated object 100 placed on the corresponding heating port 3 to a temperature suitable for cooking. A preheating mode for controlling the drive unit 7 is performed.
Note that the method of operating the preheating mode is not limited to the one that is directly instructed by the operation key 5d. For example, the display unit 6 and the operation key 5d can be selected in combination, or other cooking modes can be selected. Some may have a preheating mode. For example, when cooking grilled foods such as steak, fried eggs, and stir-fried vegetables, the preheating mode may be performed first. Thereby, the user can start cooking with the to-be-heated material 100 heated enough. In that case, the control unit 8 detects the end timing of the preheating mode using the amount of power input to the corresponding heating coil, the input time, or information from the temperature sensor 12, When finished, it has a function to notify the user and encourage cooking.

Next, the flow in this preheating mode is demonstrated using FIGS.
FIG. 8 is a heating flow in the preheating mode according to the first embodiment of the present invention, FIG. 9 is a power input diagram to each heating coil in the preheating mode according to the first embodiment of the present invention, and FIG. 10 is an embodiment of the present invention. It is a figure which shows the temperature of the to-be-heated material 100 at the time of the preheating mode which concerns on the form 1. FIG.
First, as shown in FIG. 1, the power SW 14 provided on the front surface of the main body 1 is pressed to turn on the main body (S1).
Next, when a preheating instruction is received from the operation unit 5 (S2), the control unit 8 determines whether the preheating mode may be started using the load detection unit 13 (S3). That is, the load detection unit 13 detects whether the object to be heated 100 is placed on the top plate 2 above each heating coil corresponding to the operation unit 5. And the control part 8 is arrange | positioned in the position close | similar to the temperature sensor 12 from the heating coil group judged that the to-be-heated material 100 was mounted on the top plate 2 of the upper part by the load detection part 13. FIG. The central coil 10 is set as the first heating coil, the peripheral coil 11 disposed farther from the temperature sensor 12 than the first heating coil is set as the second heating coil, and the top coil 2 is covered on the top plate 2 above it. The heating coil determined that the heated object 100 is not placed is set as the third heating coil.

In S3, if the heating coil group in which it is determined that the object to be heated 100 is placed on the top plate 2 above it does not include the central coil 10 serving as the first heating coil, Since the temperature of the heated object 100 cannot be accurately detected, it is determined that the state is not suitable for starting the preheating mode (No in S3). And it notifies to a user that heating is impossible by the display part 6 and alerting | reporting part which are not shown in figure (S3-1).
In S <b> 3, when the object to be heated 100 is properly placed, the load detection unit 13 determines the material of the object to be heated 100 in addition to the presence or absence of the object to be heated 100. And also when the material of the to-be-heated material 100 cannot be heated with an induction heating cooking appliance, the control part 8 judges that it is an unsuitable state to start the preheating mode similarly to the above (No of S3). And it notifies to a user that heating is impossible by the display part 6 and alerting | reporting part which are not shown in figure (S3-1).

  When it is determined that the state is not suitable for starting the preheating mode as described above, it is checked whether or not the result of the load detection unit 13 is changed for a predetermined time C seconds (S3-2). At this time, when there is no change in the result of the load detection unit 13 (Yes in S3-2), the preheating mode is ended (S10). If there is a change in the result of the load detection unit 13 (No in S3-2), the process returns to S3 and the object to be heated 100 is placed on the top plate 2 above each heating coil corresponding to the operation unit 5. It is detected again by the load detector 13.

On the other hand, when it is determined from the result of the load detection unit 13 that the preheating mode can be started (Yes in S3), the first heating process is performed in which the amount of power matched to the user's preheating set temperature is input to the corresponding heating coil. Implement (S4 to S6). The first heating step is performed from the start of heating until a predetermined time A, and the control unit 8 supplies power to the central coil 10 that is the first heating coil to the peripheral coil 11 that is the second heating coil. Each drive unit 7 is controlled so as to be larger than the electric power to be applied, and electric power is supplied to each corresponding heating coil (S4). Here, the control unit 8 detects the temperature of the object to be heated 100 by the corresponding temperature sensor 12 while supplying power to each heating coil. At this time, the temperature detected by the contact-type temperature sensor 12a is Tth, the temperature detected by the non-contact-type temperature sensor 12b is Tir, and threshold temperatures α and Tth, β and Tir that are set in advance for each preheating set temperature are set. In comparison, when the value of any one of the temperature sensors 12 exceeds the threshold temperature (Yes in S5), it is determined that the article to be heated 100 has reached the abnormal temperature, and the preheating mode is terminated (S10). S4 and S5 are continued until the predetermined time A has elapsed after the first heating step is started (No in S6).
Note that the temperature of the object to be heated 100 after the first heating step described above is higher than the temperature of the object to be heated 100 above the second heating coil, as shown in FIG. The temperature of the object 100 increases.

The threshold temperature α is a threshold temperature to be compared with the temperature Tth detected by the contact temperature sensor 12a, and the threshold temperature β is a threshold temperature to be compared with the temperature Tir detected by the non-contact temperature sensor 12b. . As described above, since the temperature rise of the contact temperature sensor 12a is slower than the temperature rise of the non-contact temperature sensor 12b, the threshold temperature α is set to a value lower than the threshold temperature β. In this way, by setting the threshold temperature to be different for each method of the temperature sensor 12, even when the temperature sensor 12 of a different measurement method is used, the abnormal temperature of the object to be heated 100 can be detected in the same manner. . Further, by using the two types of temperature sensors 12 of the contact type and the non-contact type in combination, the above-described weak points of the two types of temperature sensors 12 can be compensated, thereby reliably detecting the abnormal temperature of the object to be heated 100. I can do it.
Further, in S5, predetermined values determined in advance are used as the threshold temperatures α and β. However, when the temperature change rate of the object to be heated 100 is calculated separately and the temperature change rate of the object to be heated 100 is equal to or higher than the predetermined value, The threshold temperatures α and β may be changed. For example, when the rate of temperature change of the object to be heated 100 is larger than a predetermined value, it is determined that the object to be heated 100 has a high possibility of abnormally high temperature, and the threshold temperatures α and β can be determined in advance. Control to change to a value lower than the predetermined value is performed. Thereby, the abnormal temperature of the to-be-heated material 100 can be detected earlier.

Then, when the predetermined time A has elapsed since the first heating step was started (Yes in S6), the second heating step is performed (S7 to S9). In the second heating step, in order to make the temperature of the object to be heated 100 uniform, the power input to the peripheral coil 11 as the second heating coil is the power input to the central coil 10 as the first heating coil. Each drive unit 8 is controlled to be larger and power is supplied to each corresponding heating coil (S7).
Then, similarly to S5, the threshold temperatures α and β previously set for each preheat set temperature are compared with the value of the temperature sensor 12, and when the value of any one of the temperature sensors 12 exceeds the threshold temperature (Yes in S8). ) Determines that the object to be heated 100 has reached an abnormal temperature, and ends the preheating mode (S10). S7 and S8 are continued until the predetermined time B has elapsed after the second heating step is started (No in S9). In addition, since the to-be-heated material 100 has the slow temperature increase rate in many cases, the 2nd heating process is set so that it may become longer than a 1st heating process (A <B). For the same reason, control is performed so that the total amount of power input to the second heating coil in the second heating step is larger than the total amount of power input to the first heating coil in the first heating step. (See FIG. 9).
Thereafter, when the predetermined time B has elapsed since the start of the second heating step (Yes in S9), it is determined that the article to be heated 100 has been sufficiently preheated, and the preheating mode is ended (S10).
As shown in FIG. 10, the temperature of the object to be heated 100 after the second heating step described above is the temperature of the object to be heated 100 above the first heating coil and the temperature of the object to be heated above the second heating coil. The temperature of the object 100 becomes almost the same value.

  Next, each drive unit 7 is controlled so that the power input to the central coil 10 that is the first heating coil is larger than the power input to the peripheral coil 11 that is the second heating coil in S5, The significance of supplying electric power to each corresponding heating coil will be described.

For example, as shown in FIG. 11, a case where a warp pan is used as the object to be heated 100 and the warped part 100a of the object to be heated 100 is placed above the temperature sensor 12 will be described. FIG. 11 is a functional block diagram of the main part of the induction heating cooker in a state where the warp pan according to Embodiment 1 of the present invention is placed.
In a conventional induction heating cooker, when a warped pan is used as the object to be heated 100 as described above, the warped portion 100a of the object to be heated 100 is separated from the top plate 2, and therefore the magnetic flux reaching from the heating coil. Is weaker than the non-warped portion 100b of the article to be heated 100, so that the temperature of the warped portion 100a of the article to be heated 100 is lower than that of the non-warped portion 100b of the article to be heated 100. Accordingly, when the heated portion 100a of the heated object 100 is placed above the temperature sensor 12, the abnormal temperature of the non-warped portion 100b of the heated object 100 even if the non-contact temperature sensor 12b is used. The detection timing will be delayed. Further, since the amount of heat transferred from the warped portion 100a of the object to be heated 100 to the top plate 2 is reduced, the temperature rise of the top plate 2 is slower than usual. As a result, the timing at which the contact temperature sensor 12a detects the abnormal temperature of the object to be heated 100 is delayed more than the non-contact temperature sensor 12b.
As described above, when the warped portion 100a of the object to be heated 100 is placed so as to be above the temperature sensor 12, when the warped portion 100a of the object to be heated 100 reaches the threshold temperature, it is already heated. The portion 100b of the object 100 that is not warped rises to an abnormal temperature that is equal to or higher than the threshold temperature. As a result, for example, the non-warped portion 100b of the object to be heated 100 may be deformed, or the fluorine coating applied to the surface may be peeled off.

  In addition, when the thickness of the object to be heated 100 is small, the object to be heated with a small thickness is faster even when the same power is applied to the heating coil 7 as compared with the object 100 with a large thickness. The temperature rises. This is because the heat capacity of the object to be heated 100 is small. Therefore, when the warped portion 100a of the object to be heated 100, which is a warp pan, is placed above the temperature sensor 12, and the thickness of the object to be heated 100 is thin, the portion 100b of the object to be heated 100 not warped. May rise to higher temperatures.

  However, in the induction heating cooker according to the first embodiment, the power that is input to the central coil 10 that is the first heating coil immediately after the start of the preheating mode is the power that is input to the peripheral coil 11 that is the second heating coil. Each drive unit 7 is controlled so as to be larger, and a first heating step is performed in which power is supplied to each corresponding heating coil. Therefore, as shown in FIG. 10, even if the warped part 100 a of the object to be heated 100 is placed above the temperature sensor 12, the second heating coil that heats the unwarped part 100 b of the object to be heated 100. Since the electric power input to the heating object 100 is smaller than the electric power input to the first heating coil that heats the warped part 100a of the object to be heated 100, the non-warping part 100b of the object to be heated 100 is always warped. The temperature is lower than that of the portion 100a. Therefore, when the object to be heated 100 reaches an abnormal temperature, it always occurs above the first heating coil, that is, at a portion where the temperature can be detected by the temperature sensor 12. Therefore, even if the warped portion 100a of the object to be heated 100 is placed above the temperature sensor 12, the temperature sensor 12 can reliably detect the abnormal temperature of the object to be heated 100. Therefore, it is possible to prevent the problem that the non-warped portion 100b of the article to be heated 100 is deformed due to an abnormally high temperature, or the fluorine coating applied to the surface is peeled off.

Next, after each first heating step, each drive unit 8 is configured such that the power supplied to the peripheral coil 11 serving as the second heating coil is greater than the power applied to the central coil 10 serving as the first heating coil. Will be described, and the second heating step of supplying power to the corresponding heating coils will be described.
In the first embodiment, the first heating step is performed in order to prevent the heated object 100 from rising to an abnormal temperature immediately after heating. However, since the electric power supplied to the first heating coil is larger than the electric power supplied to the second heating coil in the first heating step, the temperature of the object to be heated 100 is set to the first heating coil as shown in FIG. And non-uniformity above the second heating coil. Therefore, after the first heating step, a second heating step is performed in which the power input to the second heating coil is greater than the power input to the first heating coil. By performing the second heating step in this way, the article to be heated 100 can be heated uniformly.

Next, the case where the second heating step is such that the unwarped portion 100b of the article to be heated 100 rises to an abnormal temperature will be described.
First, in the first heating step, the warped portion 100a of the article to be heated 100 is heated. Thereafter, the non-warped portion 100b of the object to be heated 100 is heated in the second heating step, and at that time, an abnormally large amount of current flows through the non-warped portion 100b of the object to be heated 100 for some reason. When the temperature starts to rise, heat is conducted also to the warped portion 100a of the article to be heated 100, and the temperature rises. At this time, the warped portion 100a of the object to be heated 100 has already been heated to some extent and has become high temperature, so even a slight rise in temperature causes the threshold temperature α or β to exceed the threshold temperature α. An abnormal temperature of the portion 100b of the heated object 100 that is not warped can be detected.

  Further, in the present embodiment, control is performed so that the electric power input in the second heating process is larger than the electric power input in the first heating process. Thereby, for example, in the case where the object to be heated 100 has a shape in which the pot skin portion is warped such as a frying pan, since the portion is greatly separated from the heating coil, it can be heated sufficiently conventionally. There wasn't. However, in the second heating step of the first embodiment, since it is sufficient to input power to the central coil 10 that is the first heating coil, more power is input to the peripheral coil 11 that is the second heating coil. I can do it. Thereby, the pot skin part of the to-be-heated material 100 which has left | separated from the top plate 2 can also be fully heated. Thus, by being able to fully preheat even the pot skin part, in cooking such as fried rice and stir-fried vegetables, it is possible to apply heat to a wide range of ingredients at once. In addition, the occurrence of uneven baking can be suppressed in cooking such as fried eggs and hot cakes.

  As described above, in the first embodiment, the control unit 8 is more temperature-sensitive than the first heating coil with respect to the first heating coil disposed at a position closer to the temperature sensor 12 that is the temperature detection unit. Power higher than that of the second heating coil disposed at a position far from the center is detected, and the temperature change of the object to be heated 100 is detected by the temperature sensor 12, and if the temperature change is outside the allowable range, the power to the heating coil is detected. Since it has the 1st heating process which stops or reduces throwing in, in the induction heating cooking appliance which heats to-be-heated object 100 using a plurality of heating coils, the warped part of to-be-heated object 100 is placed above temperature sensor 12. Even if it is placed, the abnormal temperature of the object to be heated 100 can be reliably detected. Thereby, the induction heating cooking appliance of this Embodiment 1 can heat the to-be-heated material 100, without making abnormally high temperature.

  Moreover, the control part 8 controls each drive part 7 so that the electric power input into a 2nd heating coil may become larger than the electric power input into a 1st heating coil after a 1st heating process, and it responds. Since there is a second heating step in which electric power is supplied to each heating coil, the heated object 100 warps above the temperature sensor 12 in an induction heating cooker that heats the heated object 100 using a plurality of heating coils. Even when the portion is placed, the abnormal temperature of the object to be heated 100 can be detected earlier than the conventional induction heating cooker, and the object to be heated 100 separated from the top plate 2 can be detected. The pot skin part can also be heated sufficiently.

DESCRIPTION OF SYMBOLS 1 Main body, 1a Upper surface opening edge part, 2 Top plate, 2a glass, 2b frame, 2c Intake port, 2d Exhaust port, 3 Heating port, 3a 1st heating port, 3b 2nd heating port, 3c 3rd heating port, 4 Heating part, 4a 1st heating part, 4b 2nd heating part, 4c 3rd heating part, 5 operation part, 5a 1st operation part, 5b 2nd operation part, 5c 3rd operation part, 6 display part, 6a 1st Display unit, 6b Second display unit, 6c Third display unit, 7 Drive unit, 8 Control unit, 9 Fan, 10 Central coil, 10a Inner center coil, 10b Outer center coil, 11 Peripheral coil, 12 Temperature sensor, 12a Contact Temperature sensor, 12b Non-contact temperature sensor, 13 Load detector, 14 Power supply SW, 100 Heated object, 100a Warped part of heated object, 100b Unwarped part of heated object.

Claims (6)

A top plate on which the object to be heated is placed;
A plurality of heating coils disposed below the top plate;
A drive unit for supplying high-frequency power to the plurality of heating coils;
A temperature detector that is disposed below the top plate and detects the temperature of the heated object by detecting infrared rays emitted from the heated object;
A load detection unit that detects whether the object to be heated is present on the top plate above each heating coil according to the power state when high-frequency power is supplied to each heating coil;
An operation unit that receives instructions to start and stop heating from the user,
A control unit that controls the amount of power that is input from the drive unit to the heating coil in response to an instruction from the operation unit, and the control unit is placed on the top plate above the top by the load detection unit. A group of heating coils determined to have an object to be heated is set to a first heating coil that is substantially the center of the object to be heated and a second heating coil that is the periphery of the first heating coil, and A heating coil group determined to have no heated object is set as a third heating coil,
An induction heating cooker characterized by controlling so that the total amount of power input to the second heating coil during preheating operation is greater than the total amount of power input to the first heating coil. A top plate on which the object to be heated is placed;
A plurality of heating coils disposed below the top plate;
A drive unit for supplying high-frequency power to the plurality of heating coils;
A temperature detector that is disposed below the top plate and detects the temperature of the heated object by detecting infrared rays emitted from the heated object;
A load detection unit that detects whether the object to be heated is present on the top plate above each heating coil according to the power state when high-frequency power is supplied to each heating coil;
An operation unit that receives instructions to start and stop heating from the user,
A control unit that controls the amount of power that is input from the drive unit to the heating coil in response to an instruction from the operation unit, and the control unit is placed on the top plate above the top by the load detection unit. A group of heating coils determined to have an object to be heated is set to a first heating coil that is substantially the center of the object to be heated and a second heating coil that is the periphery of the first heating coil, and A heating coil group determined to have no heated object is set as a third heating coil,
An induction heating cooker characterized in that a first heating step for supplying higher power to the first heating coil than the second heating coil is provided at the start of preheating operation. 3. The induction heating cooker according to claim 2, wherein after the first heating step, a second heating step is performed in which the second heating coil is supplied with higher power than the first heating coil. The induction heating cooker according to any one of claims 1 to 3, wherein the temperature detection unit is arranged for each heating coil. In the plurality of heating coils,
The induction according to any one of claims 1 to 3, wherein the heating coil provided with the temperature detection unit and the heating coil not provided with the temperature detection unit are disposed. Cooking cooker. The induction heating cooker according to any one of claims 1 to 5, wherein the heating coils are arranged in a grid pattern.

Images