JP3500892B2 - Cooking device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device such as a microwave oven for heating food such as food.
In particular, it relates to a heating and cooking device having a steam generating function.

[0002]

2. Description of the Related Art Conventionally, a cooking apparatus such as a microwave oven is
For example, the structure shown in FIG. 9 has been put into practical use.

FIG. 9 is a sectional view showing the structure of a microwave oven. In the figure, in an oven 32 mounted inside a housing 31, foods 34 are placed on a turntable 33, which is a food placing portion when performing dielectric heating. Reference numeral 35 is a motor for driving the turntable. Also, 2450
A magnetron 36, which is an electric wave heating means for heating an electric wave by a high frequency electric wave of MHz, is provided, and an electric wave is supplied to the oven 32 through a waveguide to heat the food 34 by the electric wave.

On the other hand, dietary habits in recent years have changed significantly in response to changes in social conditions. In particular, the progress in the production, storage, and distribution techniques of frozen foods and refrigerated foods has led to the advancement of cooked foods and foods based on them. It has made great progress in distribution and diffusion. Therefore, the dietary habits in recent years have been changed to simple and rational ones centering on cooked foods, and the demand for cooking equipment has been changed to those centering on reheating cooking.

In response to such a situation, a heating cooking device having a steam generating function added to a conventional heating cooking device has been developed. Thus, by heating the object to be heated in the oven by dielectric heating and steam in the heating atmosphere, the object to be heated such as food in the oven can be heated in a steam atmosphere at an arbitrary temperature. . Therefore,
Steam heating at a low temperature of about 60-70 ° C, steam heating at about 100 ° C, 150-
Dry steam heating at about 200 ° C. or a combination heating thereof can be performed. And since it is heat transfer by steam, it can be heated with higher heat transfer compared to normal air heat transfer, so high-speed heating is possible, and
Dry heating with dry steam, steam heating with wet steam, or combination heating thereof is freely performed, and uniform and optimum speed heating according to the type and amount of food can be performed.

The steam generator 38 uses a structure in which a metal body is induction-heated, and water is dropped on the metal body to evaporate it.
10 is a schematic view showing the entire structure of the steam generator 38, the boiler 40 is a coil 4 for generating a high frequency magnetic field.
1 is wound, and the magnetic field inductively heats the foamable metal body 43 inside the bobbin 42, and water is dropped from above. A temperature switch 44 is provided for the purpose of protecting the bobbin when the foam metal is abnormally heated.

Reference numeral 45 is a power supply for supplying a high frequency current to the coil 41, and its circuit uses a circuit configuration called a one-stone voltage resonance type circuit as shown in FIG. Reference numeral 51 is a 60 Hz commercial power source, and 52 is a rectifier consisting of full-wave rectification, which rectifies the commercial power source to form a DC power source. 41 is a coil, 55 is a first capacitor, 56 is a transistor, 5
Reference numeral 7 is a diode, and 58 is a drive circuit including an oscillator for driving the transistor 56. The coil 41 and the first capacitor 55 form a resonance circuit, and the voltage waveform of the transistor 56 becomes sinusoidal by this action. The voltage and current waveforms of the transistor 56 are as shown in FIG.

The effect of this resonance circuit is that since the current starts flowing after the voltage becomes zero, the switching loss at the time of ON (the portion where the voltage and the current overlap) is reduced. When turned off, the current sharply cuts off, but since the voltage rises in a sine wave shape, the slope becomes gentle and the switching loss at the time of off is reduced. Thus, the resonant circuit has the effect of reducing the switching loss of the transistor 56.

The drive circuit 58 gives an ON signal at the timing when the collector voltage of the transistor 6 becomes zero.

[0010]

In the steam generator of the conventional heating and cooking apparatus, the foamable metal body is heated by induction heating and water is dropped onto the metal body to generate steam. If the dropping amount is too small, or if it stops, the temperature of the metal body rises in a very short time, so that the bobbin that supports the metal body and winds the coil may be easily deteriorated. Therefore, in the conventional cooking device, a temperature switch is attached to the bobbin so that the power supply is cut off when the temperature is high. However, this structure was very difficult to install. In order to solve such a problem, the present invention provides means for indirectly detecting the temperature state of a metal body in an electric circuit, and means for protecting the metal body and the bobbin.

In addition, in order to generate steam instantaneously, 1 kW
Although the metal body is induction-heated with a certain amount of electric power, the metal body has a foamable structure in order to efficiently perform heat exchange between the metal body and water, and the heat capacity of the metal body itself is reduced to be extremely small. It is lightweight. The foamable metal body is manufactured by depositing nickel on a foamed sheet-shaped resin and then increasing the temperature to melt and remove the resin. Since unevenness occurs when nickel is vapor-deposited on the sheet-shaped resin, when the sheet-shaped resin is cut into a cylindrical shape, the weight varies depending on the cut portion. Since the variation in weight affects the electrical characteristics, the present invention defines an appropriate weight value.

[0012]

In order to solve the above-mentioned problems, the present invention utilizes the fact that the magnetic characteristics of a foamable metal body decrease as the temperature rises, thereby changing its electrical characteristics. Since the current of the diode increases as the temperature of the metal body increases, the temperature increase of the diode increases. Therefore, a temperature sensitive element is attached to the diode to detect the temperature, and the driving circuit for driving the transistor is controlled based on the information.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention is a DC power supply in order to solve the above problems, a coil connected to the DC power supply, capacitor <br/> capacitors for resonance connected in parallel or series to the coil A transistor connected in series with the coil, a diode connected in parallel with the transistor, a drive circuit for driving the transistor, and a steam that is induction-heated by a high-frequency magnetic field emitted from the coil.
And a metal body having a fire resistance of the structure to be generated, the gold
A temperature sensitive element is attached to the diode in order to detect a change in electrical characteristics when the temperature of the metal body rises , and the driving circuit is controlled by the information.

Further, current detecting means for detecting the current supplied from the DC power source is provided, the semiconductor switching element is driven so that the detection output from the detecting means becomes substantially constant, and the collector voltage of the transistor is detected. Voltage detecting means is provided, and the temperature rise of the metal body is detected by the detection output of the voltage detecting means.

Further, the current detection means for detecting the current supplied from the DC power supply, the voltage detection means for detecting the collector voltage of the transistor, the output of the voltage detection means, and the output of the current detection means are compared. The comparison means for performing is provided, and the operation of the drive circuit when the temperature of the metal body rises is controlled by the information of the comparison means.

Further, the DC power source is constructed by rectifying the commercial power source, and the current detecting means for detecting the current supplied from the commercial power source includes a current transformer whose primary side is connected to the commercial power source, and the current transformer. Between the secondary terminals
Load resistance connected in parallel with the first capacitor and the total wave rectifier circuit, the DC is connected to the DC output of the full-wave rectifier circuit
It is composed of a voltage dividing resistor for dividing the output to smooth it and a second capacitor.

The weight of the metal body is 20 g to 35 g.

Further, the metal body is formed by stacking a plurality of cylindrical foamable metal bodies having different weights, and arranging the light metal body or the heavy metal body so as not to concentrate in the central portion. To do.

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a circuit diagram of a steam generator of a heating cooker according to Embodiment 1 of the present invention.

In the figure, 1 is a DC power supply, and a capacitor 5
And the coil 4 constitute a resonance circuit and are connected to the DC power supply 1. The transistor 6 and the diode 7 are connected in parallel and connected to the resonance circuit. A driving circuit 8 drives the transistor 6. The temperature-sensitive element 10 is attached to the diode 7 to detect the temperature, and the information is transmitted to the drive circuit 8. The metal body 9 is induction-heated by the high-frequency magnetic field generated by the coil 4. Water 11 is dropped on the metal body 9 to generate steam.

This circuit structure is called a one-stone type voltage resonance type circuit, and the voltage and current waveforms of the transistor and the current waveform of the diode are shown in FIG.
It becomes like (b) and (c). This waveform is when the temperature of the metal body 9 is in a steady operation.

Since the voltage becomes sinusoidal due to the action of the resonance circuit, the circuit configuration is such that the loss during switching (ON and OFF) of the transistor 6 is extremely reduced. The drive circuit 8 gives an ON signal to the transistor 6 when the voltage of the transistor 6 becomes zero.

The resonance circuit is composed of a capacitor 5 and a coil 4, and the electric characteristic of the coil 4 is a foam metal body 9.
It greatly changes depending on. The electrical characteristics of the metal body 9 change depending on the temperature, and the magnetic permeability decreases as the temperature rises,
The change is caused by the voltage and current waveforms of the transistor and the current waveform of the diode in (a), (b) and (c) of FIG.
Influence like. That is, the diode current (c) increases (IB >> IA). The peak value of the transistor current (b) also increases, but the average value does not increase as much as the diode current. Therefore, the temperature rise of the diode 7 becomes faster than that of the transistor 6, so that the temperature state of the metal body 9 can be detected earlier by attaching the temperature sensitive element 10 such as the thermistor to the diode 7.

When the temperature of the diode 7 rises,
The temperature sensitive element 10 gives the stop information to the drive circuit 8.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. 12
Is a current detecting means for detecting an input current, and 13 is a collector voltage detecting means. Information from the current detection means 12 is transmitted to the drive circuit 8, and the drive circuit 8 controls the transistor 6 so as to keep the input current constant. Reference numeral 13 is a voltage detecting means for the collector of the transistor 6, and the information is transmitted to the comparing means 14. The comparison means 14 compares the output of the voltage detection means 13 with the reference value, and the voltage detection means 1 is more than the reference value.
When the output of 3 becomes large, a stop command is transmitted to the drive circuit 8.

Since the input power Pin and the input current Iin are in a proportional relationship and the collector voltage is in a similar relationship, the outputs of the current detecting means 12 and the voltage detecting means 13 are shown by solid lines in FIG. There is a relationship. This is a case where the metal body 9 is at an appropriate temperature, and when the metal body 9 becomes hot, the collector voltage rises and the output of the voltage detecting means 13 becomes as shown by the broken line. Since the reference value of the comparison means 14 is at the level shown in the figure, the output of the voltage detection means 13 is
When it becomes larger than this reference value, the comparison means 14 transmits an operation stop command to the drive circuit 8 to prevent the temperature rise of the metal body 9.

If the input current (input power) decreases as the temperature of the metal body 9 rises, the output of the voltage detecting means 13 when the metal body 9 is at a high temperature is as shown by the broken line, so that a certain input power P1. If it is less than (input current), it will be less than the reference value of the comparison means 14. Therefore, by controlling the input current to be constant, the high temperature state of the metal body 9 can be reliably prevented.

(Embodiment 3) A third embodiment of the present invention will be described with reference to FIG. 12
Is a current detecting means for detecting an input current, 13 is a voltage detecting means for the collector of the transistor 6, and the information is transmitted to the comparing means 14. The comparison means 14 compares the output of the current detection means 12 of the input current with the output of the voltage detection means 13,
When the output of the voltage detection unit 13 becomes larger than the output of the current detection unit 12, a stop command is transmitted to the drive circuit 8.

Since the input power Pin and the input current Iin are in a proportional relationship and the collector voltage is in a similar relationship, the outputs of the current detecting means 12 and the voltage detecting means 13 are shown by solid lines in FIG. There is a relationship. This is a case where the metal body 9 is at an appropriate temperature, and when the metal body 9 becomes hot, the collector voltage rises and the output of the voltage detecting means 13 becomes as shown by the broken line. Since the relationship between the two is reversed when the temperature of the metal body 9 is high, the comparison means 14 for comparing the output of the current detection means 12 of the input current with the output of the voltage detection means 13.
The output of is inverted and the drive circuit 8 is instructed to stop the operation.

With such a configuration, even when power control is performed, a change in the electrical characteristics of the metal body 9 in a high temperature state can be accurately detected, and a stop command is transmitted to the drive circuit 8 based on the information. The deterioration of the bobbin and the metal body can be prevented.

(Embodiment 4) A fourth embodiment of the present invention will be described with reference to FIG. A current transformer 15 is used as the current detection means 12.
The primary side of the current transformer 15 is connected to the line through which the input current flows, and the load resistor 16 and the first capacitor 17 are connected in parallel to the secondary side. Further, a full-wave rectifier circuit 18 is connected, and the DC output terminal of the full-wave rectifier circuit 18 has a voltage dividing resistor 1
9 and the third capacitor 20 are connected.

As shown in FIG. 6, the input current waveform is a current having a commercial frequency of 50 or 60 Hz. However, since the transistor 6 switches at a frequency of 20 kHz or more, the input current has the same waveform (a). ), The ripple 21 is superimposed. This ripple increases as the current of the diode 7 increases. When the ripple becomes large, the current detecting means 1 is used even if the effective value of the input current is constant.
The output voltage of 2 becomes large. This is because the output of the current transformer 15 is full-wave rectified, further divided, and smoothed by the second capacitor 20, so that the peak value of the input current is detected. Therefore, by connecting the first capacitor 17 to the secondary side of the current transformer, as shown in FIG.
If the ripple 22 having a frequency of 0 kHz or higher is smoothed, the magnitude of the input current can be accurately detected.

(Fifth Embodiment) A fifth embodiment of the present invention will be described with reference to FIGS. 4 and 7. Since the configuration shown in FIG. 4 is the same as that described in the third embodiment, the description thereof will be omitted. FIG. 7A is a characteristic table showing the weight of the metal body 9 and the detection time. This detection time is the metal body 9
When the electric power of about 1 kW is supplied to the metal body, the temperature of the metal body 9 rises, the collector voltage rises, and the output of the voltage detecting means 13 is the current detecting means 12 of the input current. This is the time required for the output of the comparing means 14 to be reversed and to give an instruction to stop the operation to the drive circuit 8 because the output becomes larger than the output.

From FIG. 3A, it is advantageous that the weight of the metal body is light because the detection time is short. This indicates that the lighter the weight of the metal body, the faster the overall characteristic changes at high temperature.

In order to hold the metal body and protect the bobbin around which the coil is wound, it is required to stop the operation within 1 minute, so the weight of the metal body is up to 35 g.

The inductance, including the metal body inserted in the coil, or the equivalent resistance is related to the cross-sectional area, density and length of the metal body. In addition, the relationship between the weight of the metal body and the output of the collector voltage detection means when the water is normally supplied and operating is as shown in FIG. If is too light, the collector voltage during normal operation becomes high, and the output of the voltage detecting means becomes the same level as the reference value. In this case, since the voltage detection means instructs the drive circuit 8 to stop the operation during normal operation, the weight of the metal body needs to be 25 g or more.

(Embodiment 6) A sixth embodiment of the present invention will be described with reference to FIG. The metal body 9 of FIG. 3A has a foamable hollow cylindrical structure using nickel, and has an inner diameter of 20 mm, an outer diameter of 33 mm, and
Although 12 pieces having a height of 10 mm are stacked, they are arranged so that a light metal body or a heavy metal body is not concentrated in the central portion. Due to the method of manufacturing the foamable metal body, the weight of each metal body varies. The magnetic field intensity generated from the coil 4 has a distribution, and as shown by the magnetic field intensity 22 in FIG. Therefore, even if the total weight of the metal body is 25 g or more and 35 g or less, if a comparatively small cylindrical metal body is placed in the vicinity 24 of the coil center, water is normally supplied and is operating. However, the collector voltage becomes high, and the detection output of the voltage detecting means for the collector voltage becomes high, and the level becomes equal to the reference value. In this case, the voltage detection means instructs the drive circuit 8 to stop the operation during normal operation.
Further, when a comparatively heavy cylindrical metal body is arranged in the vicinity 23 of the coil center, the time until detection becomes 1 minute or more. For this reason, a light metal body and a heavy metal body are combined and combined.

[0039]

As described above, according to the heating device of the present invention, the following effects can be obtained.

By attaching a temperature sensitive element to the diode, it is possible to accurately detect a change in the electrical characteristics of the metal body when the temperature rises, and by transmitting a stop command to the drive circuit based on that information, the metal The body, bobbin, and coil can be protected.

Further, a current detecting means for detecting the current supplied from the DC power source is provided, the transistor is driven so that the detection output from the detecting means becomes substantially constant, and
By providing the voltage detection means for detecting the collector voltage of the transistor, the difference in the electrical characteristics of the metal body between the normal temperature state and the high temperature state can be made noticeable, and the high temperature state of the metal body can be detected quickly and the voltage can be detected. The operation of the drive circuit can be stopped by the command of the detection means, and the bobbin and the metal body can be protected.

Further, the current detection means for detecting the current supplied from the DC power supply, the voltage detection means for detecting the collector voltage of the transistor, the output of the voltage detection means and the output of the current detection means are compared. By providing the comparison means to perform, even when performing power control, it is possible to accurately detect a change in the electrical characteristics of the metal body in a high temperature state, and by transmitting a stop command to the drive circuit by the information, Can protect bobbins and metal objects.

The total weight of the metal body is 25 g to 35 g.
By so doing, the difference in electrical characteristics between the case where the metal body is in the normal temperature state and the case where it is in the high temperature state can be made noticeable, and the temperature state of the metal body can be accurately detected.

Further, the metal body is formed by stacking a plurality of cylindrical foamable metal bodies having different weights, and arranging the light metal body or the heavy metal body so as not to concentrate in the central portion. By doing so, it is possible to reliably detect the temperature state of the metal body within the range of the total weight of the metal body from 25 g to 35 g.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a heating and cooking device according to first and second embodiments of the present invention.

[FIG. 2] (1) Waveform diagram of the circuit configuration of the heating and cooking device (2) Waveform diagram by the circuit configuration of the same cooking device

FIG. 3 is a characteristic diagram of the circuit configuration of the heating and cooking device.

FIG. 4 is a circuit diagram of a heating and cooking apparatus according to third and fourth embodiments of the present invention.

FIG. 5 is a characteristic diagram of the circuit configuration of the heating and cooking device.

6A is a waveform diagram showing an input current waveform, and FIG. 6B is a waveform diagram showing an input current waveform according to the circuit configuration of the heating and cooking apparatus of the present invention.

FIG. 7 (a) is a characteristic diagram showing the relationship between the weight of the metal body and the detection time.

FIG. 8A is a structural diagram showing the structure of a foamable metal body. (B) Characteristic diagram showing the magnetic field distribution generated from the coil

FIG. 9 is a configuration diagram of a conventional heating and cooking device.

FIG. 10 is a configuration diagram of a steam generating unit of the heating and cooking device.

FIG. 11 is a circuit diagram of the heating and cooking device.

FIG. 12 is a diagram showing voltage and current waveforms of a transistor having the same configuration.

[Explanation of symbols]

1 DC power supply 4 coils 5 capacitors 6 transistors 7 diode 8 drive circuit 9 metal body 10 Temperature sensor 12 Current detection means 13 Voltage detection means 14 Comparison means 15 Current Transformer 16 load resistance 17 First capacitor 18 Rectifier circuit 19 partial pressure resistance 20 Second capacitor

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Mihara 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-9-4849 (JP, A) JP-A-9- 4806 (JP, A) JP 62-271389 (JP, A) JP 7-322638 (JP, A) JP 7-234162 (JP, A) JP 5-329052 (JP, A) JP-A-5-62773 (JP, A) JP-A-52-16279 (JP, A) JP-A-57-90893 (JP, A) JP-A-10-116682 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05B 6/12 H05B 6/06 H05B 6/10 F24C 7/02

Claims (6)

(57) [Claims] And 1. A DC power supply, a coil connected to the DC power source, a resonance is connected in parallel or in series to the coil
And capacitor use, and transistors connected in series with said coil, a diode connected in parallel with the transistor, a driving circuit for driving the transistor, is inductively heated by the high frequency magnetic field generated from the coil
A metal body having a foamable structure for generating steam ,
In order to detect changes in the electrical characteristics of the metal body when the temperature rises,
A heating and cooking device having a structure in which a temperature-sensitive element is attached to the diode and the driving circuit is controlled by the information. 2. A DC power supply, a coil connected to the DC power supply, and a resonance connected in parallel or in series with the coil.
And capacitor use, and transistors connected in series with said coil, a diode connected in parallel with the transistor, a driving circuit for driving the transistor, is inductively heated by the high frequency magnetic field generated from the coil
And the metal body that occur steam, current detecting means for detecting a current supplied from the DC power supply, a voltage detection means for detecting the collector voltage of the transistor, the output and the standard values of the voltage detecting means and a comparing means for comparing, to drive the transistor such that the output from said current detecting means substantially constant, and configured to stop the operation of the driving circuit at a high temperature information by the metal body of the comparing means Cooked equipment. 3. A DC power supply, a coil connected to the DC power supply, and a resonance connected in parallel or in series with the coil.
And capacitor use, and transistors connected in series with said coil, a diode connected in parallel with the transistor, a driving circuit for driving the transistor, is inductively heated by the high frequency magnetic field generated from the coil
Comprising a metal body that occur steam, current detecting means for detecting a current supplied from the DC power supply, and a voltage detecting means for detecting the collector voltage of the transistor, the current detection and the output of said voltage detecting means A heating and cooking device configured to stop the operation of the drive circuit when the temperature of the metal body is high according to the information of the comparison means for comparing with the output of the means . 4. The DC power supply is configured to be obtained by rectifying a commercial power supply, and the current detection means for detecting a current supplied from the commercial power supply has a current transformer whose primary side is connected to the commercial power supply, and the current transformer. parallel between the secondary terminals of
Load resistance connected to the column and the first capacitor and the total wave rectifier circuit, the dc connected to the DC output of the full-wave rectifier circuit
The heating and cooking device according to claim 2 or 3, wherein the heating and cooking device is configured to include a voltage dividing resistor that divides the force to smooth it and a second capacitor. 5. The cooking apparatus according to claim 2, 3 or 4, wherein the metal body has a foamable structure containing nickel and the weight is 25 g to 35 g. 6. A structure in which a plurality of cylindrical foamable metal bodies having different weights are stacked, and a metal body having a light weight or a metal body having a heavy weight is arranged so as not to concentrate in a central portion. The heating and cooking device according to claim 5.