JP2003017234A - Induction heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating cooker which an oscillation noise of an inverter or a vibration noise of a pan is not easy to be heard by a user. SOLUTION: A frequency setting means 10 to set an oscillation frequency of an inverter circuit 4 is equipped, and a control means 8 drives the inverter circuit 4 by controlling a driving means 9 with a set-up oscillation frequency. When an oscillation noise of an inverter circuit 4 at an operation or a vibration noise of a pan can be heard during cooking by a user, an operation can be made outside of an audible area of a user by changing an oscillation frequency set up at the frequency setting means 10 with an input operation of the control means 7, and also, a resonance sound with the oscillation frequency of the inverter circuit 4 and a vibration frequency peculiar to the pan can be controlled, so that generation of an unpleasant noise during cooling can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating cooker, and more particularly to changing the oscillation frequency of an inverter circuit.

[0002]

2. Description of the Related Art In recent years, induction heating cookers are safe, clean, and
It has also been recognized for its excellent characteristics of high efficiency and is becoming widely used in kitchens for general households and for commercial use.

In the conventional induction heating cooker, the tabletop induction heating cooker generally changes the oscillation frequency according to the set heating output, as represented by a one-stone resonance type inverter. However, in the case of multi-induction heating cookers that have become popular in recent years, in order to suppress the interfering sound generated from the difference in the oscillation frequency of each induction heating unit when using multiple induction heating units at the same time, a half bridge inverter, etc. In this configuration, the oscillation frequency is fixed, and the set heating output is realized by changing the on / off time ratio of the switching element.

[0004]

However, in the above-mentioned conventional configuration, the oscillation frequency of the inverter circuit is fixed. Therefore, if the oscillation frequency is set to about 20 kHz to 22 kHz, the oscillation frequency of the inverter circuit may vary depending on the person. There was a case where it entered the audible range, and it was necessary to cook while the oscillation of the inverter circuit could be heard as high-frequency sound.

Also, depending on the material and shape of the pot to be heated,
Even when the oscillating frequency of the inverter circuit and the natural vibration frequency of the pan resonate, the oscillating frequency was fixed at a single frequency, and therefore cooking had to be performed with an unpleasant pan noise.

The present invention solves the above problems and provides an induction heating cooker capable of changing the oscillation frequency of a fixed frequency inverter circuit to reduce unpleasant noise generated from the cooker or the pan during cooking. To aim.

[0007]

To solve the above problems, the present invention provides an inverter circuit including a heating coil and a switching element, frequency setting means for setting an oscillation frequency of the inverter circuit, and the switching element. A driving unit for driving and a control unit for controlling the driving unit so that the output of the inverter circuit becomes a predetermined output, the control unit of the inverter circuit according to a signal from the frequency setting unit. It is an induction heating cooker that changes the oscillation frequency.

According to the present invention, it is possible to change the oscillation frequency of the inverter circuit to an arbitrary frequency, and suppress high frequency noise due to the oscillation of the inverter circuit and resonance noise between the oscillation frequency of the inverter circuit and the natural vibration frequency of the pot. can do.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 is an inverter circuit including a heating coil and a switching element,
Frequency setting means for setting the oscillation frequency of the inverter circuit, and driving means for driving the switching element,
A control means for controlling the driving means so that the output of the inverter circuit becomes a predetermined output at the set oscillation frequency, the control means according to a signal from the frequency setting means. It is an induction heating cooker configured to change the oscillation frequency of.

In the present invention, the control means can change the oscillation frequency of the inverter circuit to an arbitrary frequency in accordance with the setting in the frequency setting means. The high frequency sound generated by the oscillation of the inverter circuit and the oscillation frequency of the inverter circuit can be changed. It is possible to suppress the resonance sound of the natural vibration frequency of the pot.

The present invention according to claim 2 is provided with a plurality of inverter circuits, and the control means changes all the oscillation frequencies of the plurality of inverter circuits according to a signal from the frequency setting means. It is an induction heating cooker related to.

In the present invention, the control means can change all the oscillation frequencies of the plurality of inverter circuits to arbitrary frequencies according to the setting in the frequency setting means,
It is possible to suppress the high frequency sound due to the oscillation of the inverter circuit and the resonance sound of the oscillation frequency of the inverter circuit and the natural vibration frequency of the pan, and to change the oscillation frequency of multiple inverter circuits at the same time. It is possible to suppress the interference sound of the pot when operating.

According to a third aspect of the present invention, a cooling fan for cooling at least the switching element is provided, and the control means changes the oscillation frequency of the inverter circuit according to a signal from the frequency setting means, and the cooling fan The induction heating cooker according to any one of claims 1 and 2, wherein the number of rotations is changed.

In the present invention, when the oscillation frequency of the inverter circuit is set high, the control means operates the cooling fan at a high speed to improve the cooling capacity, thereby causing thermal destruction due to an increase in loss of the switching element. In addition, when the oscillation frequency of the inverter circuit is set to be low, the cooling fan can be operated at low speed to reduce noise generated from the cooling fan.

The present invention according to claim 4 is the induction heating cooker according to any one of claims 1 to 3, further comprising display means for displaying a setting state of the frequency setting means.

In the present invention, since the display means displays that the oscillation frequency of the inverter circuit is being changed,
The user can identify the change in the oscillation frequency at a glance.

According to a fifth aspect of the present invention, there is provided operation means for a user to input operation, and the oscillation frequency is set by the frequency setting means by input from the operation means. It is an induction heating cooker according to any one.

In the present invention, the operating means can change the oscillation frequency by the operation of the user. Therefore, when an unpleasant sound is heard from the cooker or the pan, the user can easily operate the oscillation frequency of the inverter by the operating means. Can be changed.

The present invention according to claim 6 comprises a storage means for storing the setting state of the oscillation frequency by the frequency setting means, and operates according to the oscillation frequency stored in the storage means. It is a cooking device.

In the present invention, the storage means stores the oscillation frequency of the inverter circuit. Therefore, once the user sets the oscillation frequency of the inverter circuit from the operating means, the inverter circuit operates at the desired frequency without resetting. Can be made.

[0021]

EXAMPLES Examples of the present invention will be described below.

(Embodiment 1) Embodiment 1 of the induction heating cooker of the present invention will be described below with reference to the drawings. This embodiment relates to claim 1.

FIG. 1 is a block diagram showing the configuration of this embodiment. In FIG. 1, a commercial power source 1 is full-wave rectified by a rectifier circuit 2 and smoothed by a smoothing capacitor 3 to form a DC power source. The inverter circuit 4 includes a heating coil 4a and a first resonance capacitor 4b connected in parallel with the heating coil 4a.
A first switching element 4c connected in series to the heating coil 4a, and a second switching element 4c connected in parallel to the heating coil 4a.
Connected in anti-parallel to the series circuit of the resonance capacitor 4d and the second switching element 4e, and the first switching element 4c and the second switching element 4e, respectively.
And a second diode 4g.

Reference numeral 5 is an input power detecting means for detecting the input power from the commercial power source 1, and 6 is an input power setting means, which is set to an arbitrary power by the operating means 7. Reference numeral 8 is a control means, which controls the output of the driving means 9 according to the signals from the input power detection means 5 and the input power setting means 6. Drive means 9
Is composed of a first drive circuit 9a and a second drive circuit 9b, and the first drive circuit 9a includes the first switching element 4a.
c, the second drive circuit 9b is connected to the second switching element 4
drive e respectively. 10 is a frequency setting means,
The operating unit 7 sets the oscillation frequency of the inverter circuit 4 to f1.
Alternatively, it is set to either f2. 11 is a cooling fan 1
2 is a fan drive circuit for driving 2 and 13 is frequency setting means 1
Display means for displaying the setting state of 0 and reference numeral 14 are storing means for storing the setting state of the frequency setting means 10.

The operation of the above configuration will be described.
2 is a waveform diagram showing the operation of this embodiment, FIG. 3 is a characteristic diagram showing the ratio of the audible range to the frequency, and FIG. 4 is a characteristic diagram showing the loss of the switching element with respect to the oscillation frequency. When the heating operation is started by the input from the operation means 7, the control means 8 drives the drive means 9 so that the detected power of the input power detection means 5 becomes the power set by the input power setting means 6.

The operation of the inverter circuit 4 in the steady state is as shown in FIG.
When a gate voltage is applied to the switch to turn it on, a collector current flows (period a), and then the first switching element 4c
Is turned off, the collector voltage of the first switching element 4c rises due to the resonance between the heating coil 4a and the first resonance capacitor 4b (period b). When the second switching element 4e is turned on after the first switching element 4c is turned off, resonance occurs between the heating coil 4a and the parallel circuit of the first resonance capacitor 4b and the second resonance capacitor 4d (period. c).

Since the second resonance capacitor 4d is set to have a capacity sufficiently larger than that of the first resonance capacitor 4b, while the second switching element 4e is on, the second resonance capacitor 4d causes the resonance voltage to be increased. Is clamped, and a rise in the collector voltage of the first switching element 4c is suppressed. Then, the second switching element 4
When e is turned off, resonance is caused again by the heating coil 4a and the first resonance capacitor 4b (period d), and the first switching element 4c is turned on again when the collector voltage of the first switching element 4c is near zero volt. . Figure 2
As can be seen from (b), the first switching element 4c
The input power increases as the ON time of is increased. Therefore, by changing the conduction ratio between the first switching element 4c and the second switching element 4e, the input power is controlled with the oscillation frequency fixed.

Usually, the oscillation frequency of the inverter circuit 4 is
In order to reduce the loss of the switching element, the frequency setting means 10 sets the oscillation frequency to the low frequency f1. As shown in FIG. 3, the frequency f1 is set to exceed the audible range for most people, but the frequency f1 may fall within the audible range for some people. In such a case, the frequency setting means 10 is operated by the operating means 7.
The oscillation frequency set by is higher than the frequency f1.
2 is changed to operate the inverter circuit 4.

When the oscillation frequency of the inverter circuit 4 is increased, the loss of the switching element tends to increase as shown in FIG. 4, and the temperatures of the first switching element 4c and the second switching element 4e are higher than the heat resistant temperature. Or the temperature protection circuit is provided, the cooking performance may be deteriorated due to premature cutting, so the drive voltage of the fan drive circuit 11 is changed to increase the rotation speed of the cooling fan 12. Further, when the oscillation frequency is set to the frequency f2 by the frequency setting means 10, the lamp of the display means 13 is turned on and the setting state is stored in the storage means 14.

As described above, according to this embodiment, the oscillation frequency can be changed by the frequency setting means 10. Therefore, even when the oscillation frequency of the inverter circuit 4 is in the audible range of the user, the oscillation frequency is increased. By changing it, it becomes possible to cook without hearing the oscillation sound of the inverter circuit 4.

Even if the oscillating sound of the inverter circuit 4 is not heard, the oscillating frequency of the inverter circuit 4 is changed even when the oscillating frequency of the inverter circuit 4 and the vibration frequency peculiar to the pot resonate with each other to generate a beat noise. Resonance sound can be reduced by changing it.

If the frequency setting means 10 and the control means 8 are constituted by a microcomputer, the oscillation frequency can be changed with a simple structure.

Further, since the rotation speed of the cooling fan 12 can be changed when the oscillation frequency is changed by the frequency setting means 10, the rotation speed of the cooling fan 12 can be lowered to reduce noise when operating at a low frequency. When operating at a high frequency, the rotation speed can be increased to suppress thermal destruction of the switching element and deterioration of cooking performance due to premature disconnection of the temperature protection circuit.

Further, by displaying on the display means 13, the setting state by the frequency setting means 10 can be recognized at a glance.

Further, since the frequency can be set by the operating means 7, it becomes possible to change the oscillation frequency according to the user or to change the oscillation frequency according to the pan to be used.

Further, by storing the set frequency in the storage means 14, once the oscillation frequency of the inverter circuit 4 is set by the frequency setting means 10, it is possible to operate at the desired frequency without having to set it again. Become.

Although the frequency setting means 10 sets the frequency in two steps in the present embodiment, the number of frequency setting steps is not limited. Further, the same effect can be obtained for the inverter circuit 4 as long as it is a frequency fixed inverter such as a full bridge or a half bridge. Also, the frequency setting means 1
Although the setting method of 0 is the input from the operation means 7, the same effect can be obtained by a method of setting by setting a dip switch on the substrate or a method of changing the input to the microcomputer by combining resistors. be able to.

(Embodiment 2) Hereinafter, Embodiment 2 of the induction heating cooker of the present invention will be described with reference to the drawings. This embodiment relates to claim 2.

FIG. 5 is a block diagram showing the configuration of this embodiment. In addition, the same components as those of the first embodiment shown in FIG. In this embodiment, a plurality of inverter circuits are provided.

In FIG. 5, reference numeral 15 is a second rectifier circuit for full-wave rectifying the commercial power supply 1 to convert it into direct current, 16 is a second inverter circuit, 17 is a second input power detecting means, and 18 is a second. The input power setting means 19 is a second control means for driving the second driving means 20 in response to signals from the second input power detecting means 17 and the second input power setting means 18.

The operation of the above configuration will be described.
When the frequency setting means 10 operates the inverter circuit 4 in a state where the oscillation frequency is set to the frequency f1 to perform heating and the oscillation frequency is heard as a sound in the audible range of the user, the frequency setting means 10 sets the frequency. Change to f2. When the oscillation frequency is changed to the frequency f2 by the frequency setting means 10, both the inverter circuit 4 and the second inverter circuit 16 are controlled so that the oscillation frequency becomes the frequency f2.

As described above, according to this embodiment, when a plurality of inverter circuits are provided, all the inverter circuits are operated so as to have the frequency set by the frequency setting means 10. Therefore, the oscillation frequency of the inverter circuit is set. Even if the product is in the user's audible range, it is possible to cook without hearing the oscillating sound by changing the oscillating frequency to a high level, and the interference sound is generated when multiple inverter circuits are operated at the same time. Can be suppressed.

In this embodiment, the case where two sets of inverter circuits are provided has been described, but the present invention is not limited to this.

[0044]

As is apparent from the above description, according to the present invention, the oscillation frequency of the inverter circuit can be changed so that it can be operated outside the audible range of the user. Since the resonance sound with the inherent vibration frequency can be suppressed, the generation of unpleasant sound during cooking can be reduced. Further, when a plurality of inverter circuits are provided, the oscillation frequency can be changed so that all the inverter circuits have the same frequency, so that the generation of interference sound due to the simultaneous use of the plurality of inverter circuits can be suppressed.
Further, the rotation speed of the cooling fan can be changed to reduce the noise of the device when operating at a low frequency. Also,
The setting state of the frequency setting means can be identified at a glance. Also, to provide an easy-to-use induction heating cooker that can set the oscillation frequency according to the person who uses the cooker and the pot to be heated, and does not need to be set again once the oscillation frequency is set. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an induction heating cooker according to a first embodiment of the present invention.

FIG. 2 is a waveform chart showing the operation of the embodiment.

FIG. 3 is a characteristic diagram showing a ratio of an audible range to a frequency in the example.

FIG. 4 is a characteristic diagram showing a loss of a switching element with respect to an oscillation frequency in the example.

FIG. 5 is a block diagram showing the configuration of Example 2 of the induction heating cooker according to the present invention.

[Explanation of symbols]

1 Commercial power supply 2 rectifier circuit 3 smoothing capacitors 4 Inverter circuit 4a heating coil 4b First resonance capacitor 4c First switching element 4d second resonant capacitor 4e Second switching element 4f first diode 4g second diode 5 Input power detection means 6 Input power setting means 7 Operation means 8 Control means 9 Drive means 9a First drive circuit 9b Second drive circuit 10 Frequency setting means 11 Fan drive circuit 12 Cooling fan 13 Display means 14 storage means 15 Second rectifier circuit 16 Second inverter circuit 17 Second input power detection means 18 Second input power setting means 19 Second control means 20 Second drive means

Claims (6)

[Claims] 1. An inverter circuit including a heating coil and a switching element, frequency setting means for setting an oscillation frequency of the inverter circuit, driving means for driving the switching element, and the inverter at the set oscillation frequency. A control means for controlling the driving means so that the output of the circuit becomes a predetermined output, and the control means changes the oscillation frequency of the inverter circuit according to a signal from the frequency setting means. Induction heating cooker. 2. The induction heating cooker according to claim 1, further comprising a plurality of inverter circuits, wherein the control means changes all the oscillation frequencies of the plurality of inverter circuits according to a signal from the frequency setting means. 3. A cooling fan for cooling at least the switching element is provided, and the control means changes the oscillation frequency of the inverter circuit in accordance with a signal from the frequency setting means and also changes the rotation speed of the cooling fan. The induction heating cooker according to any one of claims 1 to 2. 4. The induction heating cooker according to claim 1, further comprising display means for displaying a setting state of the frequency setting means. 5. An operating means for a user to input an operation is provided,
The induction heating cooker according to any one of claims 1 to 4, wherein the oscillation frequency is set by the frequency setting means by an input from the operation means. 6. The induction heating cooker according to claim 5, further comprising storage means for storing the setting state of the oscillation frequency by the frequency setting means, and operating at the oscillation frequency stored in the storage means.