JP2978069B2 - Electromagnetic cooker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic cooker, and more particularly to a heating coil and a power supply system for outputting high-frequency power to the heating coil.

[0002]

2. Description of the Related Art An electromagnetic cooker includes a heating coil in which a conductor such as a litz wire is spirally wound from the center toward the outer periphery, and a high-frequency power generation circuit (power supply) for outputting high-frequency power to the heating coil. And a top plate provided substantially parallel to the main surface of the heating coil on the cooking device housing frame, and outputting a high-frequency power to the heating coil to heat an object to be heated on the top plate, for example, a cooking pot. Is what you do. Usually, the heating coil is formed in a flat spiral shape having a relatively small coil diameter with respect to the cooking pot, and only one high-frequency power generation circuit is provided for the heating coil. The heating of the cooking pot is performed on a portion of the pot bottom that is close to the heating coil and that faces the main surface.

[0003]

As described above, the heating of the cooking pot by the electromagnetic cooker is performed on a portion of the pot bottom which is directed to the main surface of the heating coil, and thus the bottom diameter is smaller than the diameter of the heating coil. A cooking pot having a small diameter (hereinafter referred to as a small pot for convenience) does not pose a significant problem in terms of heating power, but has a bottom diameter much larger than the diameter of the heating coil (hereinafter referred to as a large pot). About the pot)
Since the heating can be performed only in a narrow area as small as the diameter of the heating coil, the heating pattern at the bottom of the pot is extremely unbalanced, and there is a problem that cooking becomes inconvenient. In this case, sufficient heating power can be obtained by increasing the diameter of the heating coil. However, in such a case, the heating power in the annular region near the outer periphery of the heating coil becomes relatively stronger than that in the central portion, and the heating pattern becomes donut. As a result, the above cooking problem cannot be solved, but rather promotes the problem.

When a small pot whose bottom diameter is smaller than the diameter of the heating coil is placed on the top plate and heated, a portion of the heating coil that does not contribute to induction heating, that is, a no-load region appears in a ring shape. The high-frequency magnetic field in the no-load region leaks around the small pan, causing the following problems. (1) The heating power of the small pot becomes insufficient. (2) The area around the small pot is abnormally heated. (3) In the case of a pan or a frying pan having a metal handle, the handle is heated up to the handle and becomes difficult to handle. (4) Another metal cookware placed around the small pot is heated. (5) Harmful or unnecessary radio noise increases, and particularly adversely affects electronic devices worn on the human body, such as watches and magnetic cards.

An object of the present invention is to solve such a problem,
The heating pattern is improved for an object to be heated such as a large pot, and at least the above-mentioned problems (1) to (5) do not occur for an object to be heated such as a small pot. To provide equipment.

[0006]

According to the present invention, there is provided an electromagnetic cooker comprising: a plurality of heating coils having different diameters arranged concentrically and on substantially the same plane; possess a high-frequency power generation circuit for supplying a, and an output control means for controlling the output of the high frequency power circuit, this
Output control means supplies power to one adjacent heating coil
Is turned on, the power to the other heating coil is turned off.
As well as the output level and
Duty ratio and / or output time interval
It is configured to adjust a combination of features that you have. In the electromagnetic cooking device having the above-described configuration, the plurality of heating coils are configured such that , for example, current flows through one of the adjacent coils.
Ru der those wound so as to suppress the induced current flowing through the other coil when the. More specifically, the adjacent
One of the coils and the other coil are opposite to each other
And wind it up. The high-frequency power generation circuit includes, for example, a plurality of resonance capacitors each constituting a resonance circuit with the plurality of heating coils, and a resonance determined by a capacitance value of each resonance capacitor and an inductance value of the heating coil. The power of the frequency is output to the heating coil. In this case, the resonance frequency of one resonance circuit reduces the frequency that suppresses electromagnetic interference with the adjacent resonance circuit.
Wave number .

According to another aspect of the electromagnetic cooker provided by the present invention, in the electromagnetic cooker having the above-described structure, a sensor for detecting an energized state of each of an inner heating coil and an outer heating coil among the plurality of heating coils. And the output signal of this sensor
Means for feeding back the output to the output control means.
And the output control means cooks the inner heating coil.
Insufficient for use, but the presence of the object to be heated is at least
Level power, and the feedback
Near the inner heating coil based on the output signal
To determine whether there is an object to be heated,
If the judgment is successful, stop supplying power to the inner heating coil.
To supply the electric power to the outer heating coil,
Based on the output signal fed back
The size of the object to be heated is determined, and the determined
It is configured to perform power supply control corresponding to the size of heat
It is characterized by having.

[0008]

According to the electromagnetic cooker of the present invention, one flat spiral coil is divided to form a plurality of heating coils, or a plurality of heating coils having different diameters are arranged concentrically and substantially on the same plane. High frequency power is individually output to each heating coil. At this time, the output control means controls the output of the high-frequency power generation circuit, and switches the high-frequency power output to each heating coil in a time-division manner. This makes it possible to realize a mode in which only the heating coil near the center is energized manually or automatically, a mode in which each heating coil is alternately switched at predetermined time intervals, and the like. By variously adjusting the output level of the high-frequency power, the duty ratio, the output time interval, or a combination thereof by the control circuit, the heating pattern of the object to be heated according to the type of cooking can be arbitrarily changed. When the adjacent spiral heating coils are wound in opposite directions, the induction current of the other heating coils during the output control of the high-frequency power can be reduced.

By the way, each heating coil has a different energized state when an object to be heated exists in the vicinity thereof and when it does not exist. Therefore, if the energized state of each heating coil is detected by a sensor, the presence or absence of the object to be heated or its size can be determined from the output of each sensor. In the present invention, a determination means for that purpose is provided, and the output control means controls at least one of the output level of the high-frequency power and the output time to each heating coil based on the output result of the determination means. This facilitates the automation of the above-described mode selection, and enables effective heating according to the size of the object to be heated.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) FIG. 1 is a main part configuration diagram showing a configuration of an electromagnetic cooker according to a first embodiment of the present invention. In FIG.
Reference numeral 1 denotes a circular or polygonal heating coil in which a litz wire is wound in a flat spiral shape.
S2, intermediate terminals S1A and S2A are provided at the coil intermediate portion, and the inner end terminal S1 and the intermediate terminal S1A at the center portion have the inner coil 11, the outer edge end terminal S2 and the intermediate terminal S2A.
And constitute the outer coil 12, respectively. Note that the present invention is characterized in that a plurality of heating coils are independently controlled to adjust the overall heating pattern in various ways. For convenience, a case in which only two heating coils are used will be described.

Reference numerals 2A and 2B denote inner coils 1 respectively.
Reference numeral 3 denotes a control circuit for controlling the output of the high-frequency power generation circuit 2 for outputting high-frequency power to the first coil 1 and the outer coil 12. Also, reference numeral 4
Denotes an operation display circuit including a heating on / off switch, a heating mode selection switch, a heating level setting volume, an alarm display, and the like, and reference numeral 5 denotes a top plate made of an insulating material.

The control circuit 3 has a timing control circuit and a level setting circuit (not shown). The timing control circuit turns on / off the output of each of the high-frequency power generation circuits 2A and 2B in a time-sharing manner in accordance with an instruction from the operation display circuit 4 to adjust the duty ratio of the output power or the output time interval.
The level setting circuit generates the off signals T1 and T2, and generates the level setting signals P1 and P2 for adjusting the output level of each of the high-frequency power generation circuits 2A and 2B (output control means). .

FIG. 2 shows a specific configuration example in the case where the above-described high-frequency power generation circuits 2A and 2B are realized by two half-bridge circuits. These half bridge circuits 22A, 22
2B is a DC circuit 21 that rectifies commercial power (AC power).
This is a kind of resonance circuit that converts the output power of the device into high-frequency power. Referring to FIG. 2, the first half-bridge circuit 22
The terminal terminal S1 of the inner coil 11 is conductively connected to the middle point of the transistor arm forming the A through the resonance capacitor C1, and the resonance terminal is connected to the middle point of the transistor arm forming the second half bridge circuit 22B. The end terminal S2 of the outer coil 12 is conductively connected via the transistor C2. The intermediate terminals S1A and S2A are conductively connected to an intermediate point between the common bypass capacitors C3 and C4. The resonance frequency f1 of the high-frequency power output to the inner coil 11 is substantially determined by its inductance value and the capacitance value of the resonance capacitor C1,
Resonance frequency f of high frequency power output to outer coil 12
2 is substantially determined by the inductance value and the resonance capacitor C2. It is preferable that these resonance frequencies f1 and f2 are separated from each other so that the coils 11 and 12 do not electromagnetically interfere with each other. The present inventors have verified that there is no practical problem if one resonance frequency is at least 1.2 times or more the other resonance frequency. Note that each of the capacitors C1 to C4 can be replaced with a variable capacitor. The output times and output levels of the half bridge circuits 22A and 22B are controlled by the transistor drive signals D1 and D2 input from the control circuit 3. The transistor drive signals D1 and D2 correspond to the on / off signals T1 and T2 shown in FIG.
And has the same function as the level setting signals P1 and P2. Half bridge circuits 22A, 22 as described above
When B is used, two high-frequency power generation circuits 2A and 2B can be realized with a simple circuit configuration. Although the above is an example of a circuit configuration suitable for reducing the cost, the high-frequency power generation circuits 2A and 2B required for implementing the present invention are:
The present invention is not necessarily limited to the case where the above-described half bridge circuits 22A and 22B are used, and it goes without saying that the configuration may include another high-frequency oscillation circuit.

FIGS. 3A and 3B are explanatory diagrams of a case where the small pot 6 is heated using the electromagnetic cooker of the present embodiment, and FIG. The hatched portions of each of the heating coils 11 and 12 indicate a state in which electricity is supplied. In this case, in accordance with an instruction from the operation display circuit 4, the level setting circuit of the control circuit 3 is connected to the high-frequency power generation circuit 2 connected to the inner coil 11.
The output level of A is adjusted from zero to the rated value (100%), and the output level of the high-frequency power generation circuit 2B connected to the outer coil 12 is set to zero.
Alternatively, the output duty ratio of the high-frequency power generation circuit 2A connected to the inner coil 11 is set to 10 by the timing control circuit.
Adjust to 0%. Each high-frequency power generation circuit 2 at this time
The output states of A and 2B are shown in FIG. According to such a control example, the inner coil 1 located at the bottom of the small pan 6
Since high-frequency power is selectively concentrated only on 1 and no no-load area is generated around the high-frequency power, leakage of high-frequency magnetic field is suppressed,
Various conventional problems that have occurred in the case of the small pan 6 can be solved.

FIGS. 4A and 4B are explanatory diagrams in the case of heating the large pan 7 using the electromagnetic cooker of the present embodiment. FIG. 4A is a configuration diagram of the main part, and FIG. FIG. 6 is an output state diagram of each of the high-frequency power generation circuits 2A and 2B to be executed. In the figure,
t1 and t2 are output times of the high-frequency power. The hatched portions of each of the heating coils 11 and 12 indicate a state in which electricity is supplied.

In this example, the output of the high-frequency power is set from zero to a rated value (100%) by the level setting circuit of the control circuit 3 according to the instruction of the operation display circuit 4, and the output duty ratio is set by the timing control circuit. Various changes are made. That is, the output of the first high-frequency power generation circuit 2A and the output of the second high-frequency power generation circuit 2B are alternately turned on / off according to a predetermined time ratio, and the output of the former is output at time t.
After turning on only 1 (ON), off for time t2 (OFF)
This is repeated, and the latter output is output at time t1.
This is repeated after turning off only for time t2. In such a control example, the heating pattern at the bottom of the pot can be arbitrarily changed by changing the ratio of each time t1 and t2 and each output level, and various heating patterns suitable for the type of cooking can be formed. .

The times t1 and t2 are 0 to 0, respectively.
It is variable up to about 3 seconds, and when t2 is set to 0, a continuous output state as shown in FIG. 3B is obtained, and a control example suitable for selectively heating only the inner part of the large pan 7 is provided. Become. Further, the level setting circuit and the timing control circuit may independently control the outputs of the high-frequency power generation circuits 2A and 2B, or may control the combination of both.
In the latter case, fine control of the heating pattern becomes possible, and the conventional problems can be solved more effectively.

The first embodiment of the present invention is as described above. In addition to fixing the positions of the intermediate terminals S1A and S2A as described above, the positions of the intermediate terminals S1A and S2A are made variable so that the inductance value and the resonance frequency can be changed. You may change it. Also,
As in the above embodiment, in addition to the configuration in which one flat spiral coil is divided into a plurality of heating coils, a plurality of independent heating coils having different diameters are arranged concentrically and substantially on the same plane. May be.

[0019] (Second Embodiment) FIG. 5 is a Ru main part configuration diagram der of the electromagnetic range according to the second embodiment of the present invention. This electromagnetic cooker is evident from FIG.
In the electromagnetic cooker having the configuration shown in the first embodiment, the inner coil 11 and the outer coil 12 'concentrically and substantially on the same plane are wound so that the currents flow in opposite directions. is there. 2'A and 2'B are coils 11 and 12 '
High-frequency generation circuit that outputs high-frequency power to
2 'and S2'A are terminals of the outer coil 12', and their individual functions are the same as those shown in the first embodiment.

In this embodiment, a sensor L1 for detecting the coil current of the electric circuit is provided on the common power line between the intermediate terminals S1A and S2'A of the inner coil 11 and the outer coil 12 '. The signal HF1 is fed back to the control circuit 3 '. The control circuit 3 'regenerates the on / off signals T1, T2 and / or the level setting signals P1, P2 based on the output signal HF1, and outputs the signals to the high frequency power generation circuits 2'A, 2'B. .

FIG. 6 shows a configuration diagram in the case where the high-frequency power generation circuits 2'A and 2'B are realized by two half-bridge circuits. In this example, in the configuration shown in FIG. 2, the winding direction of the outer coil 12 'is reversed, and the intermediate terminals S1A, S2' of the inner coil 11 and the outer coil 12 'are further set.
The sensor L1 is provided on the common power line of A, and the output signal HF1 of the sensor L1 is fed back to the control circuit 3 '. The control circuit 3 'regenerates the transistor drive signals D1 and D2 based on the output signal HF1 and outputs it to each of the high-frequency power generation circuits 2'A and 2'B.

Next, the operation when the inner coil 11 and the outer coil 12 'are wound in opposite directions as described above will be described with reference to FIGS. FIG. 7 is a partial configuration diagram of FIG. 6, in which a common power line of each of the coils 11, 12 'is conductively connected to an intermediate point between the common bypass capacitors C3, C4. Here, the current flowing through the inner coil 11 is represented by I ₁ ,
If thereby the induction current induced in the outer coil 12 'i _2, the variation in the intermediate voltage bypass capacitor C3, C4 and [Delta] V, these currents I ₁ and the current i ₂ is FIG.
Since shown in opposite directions to each other as, fluctuations component ΔV acts in a direction to suppress the induced current i ₂ of the outer coil 12 '. FIG.
(A) is a state explanatory diagram at this time, in which the solid line is the current I ₁ flowing through the inner coil, the thin line is the induced current i ₂ , and the broken line is the variation ΔV. FIG. 8B is a state explanatory diagram when all the coils are set in the forward direction, and shows how the voltage fluctuation ΔV works in a direction to increase the induced current i ₂ . Note that the above is an example in which high-frequency power is output only to the inner coil 11, but the same relationship applies to a case where high-frequency power is output only to the outer coil 12 '. In this way, by inverting the directions of the currents flowing through the coils 11, 12 ' , the current induced by the other coils is suppressed, so that the output signal H of the sensor L1 is reduced.

(Third Embodiment) FIG. 9 is a structural view of a main part of an electromagnetic cooker according to a third embodiment of the present invention, wherein 51 is an inner coil, 52 is an outer coil, 53 is a DC circuit, and 54A and 54A. 5
4B is a high frequency power generation circuit, and 55 is a control circuit. Although the coils 51 and 52 are shown separately for the sake of convenience, a single flat spiral coil may be divided into a predetermined number of turns as in the first embodiment. In addition, the winding direction of each of the coils 51 and 52 may be either a forward direction or a reverse direction. DC circuit 53 and high frequency power generation circuit 5
4A and 54B are the same as those in the first embodiment.

In this embodiment, the sensors L1 and L1, which detect the current in the electric circuit, are respectively connected to the common power line of the inner coil 51 and the outer coil 52 and the power line of the power input section (AC input section).
2 is provided to detect the current level of each part, and a heated object discriminating circuit (discriminating means) for discriminating the size of the pot based on the output of each sensor is provided in the control circuit 55. High-frequency power is automatically output only to the inner coil 51. The sensor L1 is the same as that described in the second embodiment, but is not used here for feedback to the control circuit 55, but for determining the presence or absence of a pan and its size as described below. Used. In the illustrated example, one sensor L1 is provided on the common power line, but a configuration may be provided separately around each of the coils 51 and 52.

[0025] In such a configuration, the output signal HF1 of the sensor L1 when the pot is in the disposed position of the inner coil 51 on the top plate is smaller than the output signal I _AC sensor L2, becomes large when there is no pot . The same applies to the case of the outer coil 52. Therefore, these sensors L1, L2
Of the output signal HF1, by comparing the combination of I _AC, it is possible to identify the presence and size of the pan.
FIG. 10 shows a processing procedure of the control circuit 55 utilizing this property.

Referring to FIG. 10, first, the lowest level of high-frequency power is output only to the inner coil 51 at the same time as the heating is turned on (S (processing step, the same applies hereinafter) 101). This minimum level is not enough for cooking,
This level is sufficient for / OFF discrimination, and is set in advance by a level setting circuit in the control circuit 55. Then, the output signal HF1 of the sensor L1 at that time is compared with the output signal I _AC of the sensor L2 of the power input unit to determine whether or not the pan is on the top plate (S102). At this time, if there is no pot, it waits at the lowest level until the pot is placed on the top plate. On the other hand, when there is a pan, the output (power supply) of the high-frequency power to the inner coil 51 is temporarily stopped (S
103) Immediately, the same level of high-frequency power is output to the outer coil 52 (S104), and it is determined whether or not there is a pot (S105). If it is determined here that there is no pot, the inner coil 51 has a pot and the outer coil 52 does not have a pot, so that it is understood that the one placed on the top plate is a small pot. In this case, the heating control of the small pan, that is, the output of the high-frequency power at the set level to the inner coil 51 is performed (S106). On the other hand, if the outer coil 52 also has a pot, the large plate is placed on the top plate, so that the heating control of the large pot, that is, the inner coil 51
The timing control circuit and / or the level setting circuit are adjusted so as to obtain an optimal heating pattern for cooking using both the outer coil 52 and the outer coil 52 (S107).

As described above, the present invention has been described using a plurality of embodiments. However, the present invention is not limited to the configuration of each embodiment, and a design change can be made without departing from the scope of the present invention. Of course.

[0028]

As is apparent from the above description, according to the present invention, the output control of the high-frequency power to a plurality of heating coils having different diameters can be individually performed, so that it was impossible in the prior art. Various heating patterns can be formed. For example, high-frequency power can be intensively output only to a heating coil located in the vicinity of a portion to be selectively heated, or output of high-frequency power to a heating coil that does not contribute to induction heating can be stopped for a predetermined time. Many conventional problems caused by generation of an impossible biased heating pattern or a no-load region can be solved at once.

Further, the energized state of the power input section and the energized state of each heating coil are detected by a sensor, and the presence or absence or size of the object to be heated is determined based on a combination of the outputs of the sensors, and the output result is obtained. , At least one of the output level and the output time of the high-frequency power to each heating coil is controlled, so that it is easy to automatically select various heating patterns for the object to be heated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of an electromagnetic cooker according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a specific configuration example when the high-frequency power generation circuit of the first embodiment is realized using a half-bridge circuit.

FIG. 3 (a) is a main part configuration diagram when heating a small pot in the first embodiment, and (b) is a diagram of each high-frequency power generation circuit when intensively heating the center of the pot bottom of the small pot. Output state explanatory drawing.

FIG. 4A is a configuration diagram of a main part when a large pan is heated in the first embodiment, and FIG. 4B is an output state of each high-frequency power generation circuit when the pan bottom of the large pan is uniformly heated. FIG.

FIG. 5 is a main part configuration diagram of an electromagnetic cooker according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating a specific configuration example when the high-frequency power generation circuit according to the second embodiment is realized using a half-bridge circuit.

FIG. 7 is a partial configuration diagram for explaining the operation of the second embodiment.

FIG. 8 (a) is a state explanatory diagram of ΔV showing the variation of the coil current I1, the induced current i2, and the intermediate voltage of the bypass capacitors C3 and C4 when the winding directions of the inner coil and the outer coil are reversed. (b) is a state explanatory view when all the coils are set in the forward direction.

FIG. 9 is a main part configuration diagram of an electromagnetic cooker according to a third embodiment of the present invention for determining the size of a pot.

FIG. 10 is a flowchart showing a processing procedure until a location of a pot is specified in the control circuit having the configuration of FIG. 9;

[Explanation of symbols]

 1,1 'Heating coil 11,51 Inner coil 12,12', 52 Outer coil 2A, 2B, 2'A, 2'B High frequency power generation circuit 3,3 ', 55 Control circuit 4 Operation display circuit 5 Top plate 6 Small pan 7 Large pan L1, L2 Sensor to detect coil current of electric circuit

──────────────────────────────────────────────────続 き Continued from the front page (72) Yoshio Tauchi, Inventor 2-3-1 Shibasaki, Chofu-shi, Tokyo Shimada Rika Kogyo Co., Ltd. (56) References JP-A-4-337279 (JP, A) JP-A-3 JP-A-238784 (JP, A) JP-A-63-291387 (JP, A) JP-A-3-203187 (JP, A) JP-A-57-192690 (JP, U) (58) Fields investigated (Int. . ⁶ , DB name) H05B 6/12

Claims (5)

(57) [Claims] 1. A plurality of heating coils having different diameters arranged concentrically and substantially on the same plane, a high-frequency power generation circuit for individually supplying high-frequency power to each heating coil, Output control means for controlling the output.
And, the output control means includes a sheet to one adjacent heating coils
When the power is on, supply power to the other heating coil.
Turn off the output level of each high-frequency power,
At least one of duty ratio and output time interval or this
Electromagnetic cooker characterized that you have been configured to adjust the combination of al. 2. The heating coil according to claim 1, wherein the plurality of heating coils are adjacent to each other.
When current flows through one of the coils,
The electromagnetic cooker according to claim 1, wherein the electromagnetic cooker is wound so as to suppress the conductive current . 3. The one and the other coil of said adjacent coil
The electromagnetic cooker according to claim 2, wherein the coils are wound so as to be opposite to each other . 4. The high-frequency power generation circuit includes a plurality of resonance capacitors each forming a resonance circuit with the plurality of heating coils, and a capacitance value of each resonance capacitor and an inductance value of the heating coil. Output power of the determined resonance frequency to the heating coil
It is those, electrodeposition between the resonant circuit of the adjacent resonance frequency of one resonance circuit
Claims characterized by a frequency that suppresses magnetic interference
Item 6. The electromagnetic cooker according to item 1, 2 or 3 . 5. The electromagnetic cooker according to one of claims 1 to 4, the inner one of the plurality of heating coils
A sensor for detecting a current-carrying state of each of the heating coil and the outer heating coil, and an output signal of the sensor being fed back to the output control means.
Means for cooking , wherein the output control means is provided for cooking on the inner heating coil.
Is not sufficient, but the presence of an object to be heated is
Before power is fed back
The output signal is applied to the vicinity of the inner heating coil.
Determines whether there is a heated object and determines that there is an object to be heated
When possible, stop supplying power to the inner heating coil
Supplying the electric power to the outer heating coil;
The target pressure based on the feed-back said output signal
Determine the size of the heated object and the determined heated object
Power supply control corresponding to the size of the
Electromagnetic cooker, characterized in that that.