JPH0436295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high-frequency heating device having a function of detecting the heating state of a heated object and controlling the heating output.

Conventional technology Conventionally, the output control of high-frequency heating equipment was set by the user using a time switch, etc., but since the type and amount of the heated object differs each time, the user has to adjust the output control to suit the heated object. In addition, it was extremely difficult to set the time for heating to a desired temperature. Therefore, a method has been proposed in which the amount of steam generated depending on the degree of heating of the object to be heated is detected as a change in humidity, and the output is controlled based on this signal. (JP-A-52-101743, JP-A-52-101743, JP-A-52-101743,
103733 Publication) Problems to be Solved by the Invention However, with this configuration, it is difficult to obtain stable detection performance for detecting the degree of heating of foods made of a wide variety of materials and shapes. Therefore, there was a problem that although food items on a limited menu could be successfully detected, other menu items could not be detected correctly. In addition, this device is often installed in relatively small kitchens, but in such harsh environments where heat and steam generated from boiling food and other cooking equipment tend to fill, it is necessary to install these devices outside the kitchen. Easily affected by the environment, JP 52-101743
There was a problem that stable detection could not be performed with the configuration described in the above publication. Furthermore, JP-A-52-
In the configuration described in Publication No. 103733, etc., the air in the heating chamber is guided to the sensor by suction, so the air in the heating chamber is in a static state, so signals such as steam caused by local heating of food are not concentrated. There was a problem that the detection timing was unstable because the sensor reached the sensor with unevenness.

The present invention solves these problems and provides a high-frequency heating device that performs highly reliable output control by achieving stable detection accuracy.

Means for Solving the Problems The high-frequency heating device of the present invention includes a main body having a heating chamber for accommodating an object to be heated therein, and an opening for taking the object into and out of the heating chamber that can be opened and closed. a high-frequency oscillator that generates high-frequency output to be supplied into the heating chamber; a fan that cools the high-frequency oscillator; An intake aperture for introducing air, an exhaust aperture for discharging the air that entered through the intake aperture to the outside of the heating chamber, and an exhaust aperture for discharging the air exhausted from the exhaust aperture to the outside of the main body. An exhaust hole provided in a part of the main body, a detection means for detecting physical changes such as humidity in the air discharged from the exhaust opening, and an output control means for controlling high frequency output based on a signal from the detection means. , the fan is composed of a propeller fan, and the exhaust opening and the exhaust hole are
The exhaust hole is communicated with an exhaust guide having the detection means therein, and the total opening area of the exhaust hole made up of a plurality of openings is larger than that of the exhaust opening. .

Function The high-frequency heating device of the present invention does not directly lead the steam accompanying local heating of food to the detection means.
The configuration uses a propeller fan to forcibly blow air into the heating chamber, and the total opening area of the exhaust hole in the main body, which is made up of multiple openings, is larger than that of the exhaust hole in the heating chamber, which results in local heating. This system agitates and dilutes the steam of the main body to prevent so-called premature burnout, as well as quickly and reliably detect a signal when the entire heated object is heated, and prevent malfunctions that are not affected by the external environment around the exhaust hole outside the main unit. The aim is to provide a highly reliable microwave oven without any problems.

Embodiment Hereinafter, a high frequency heating device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a front cross-sectional view of a high-frequency heating device according to the present invention, and FIG. 2 is a top view of a cross-section taken along line A-A' in FIG. The main body 1 is provided with a heating chamber 2 with an open front surface, and a heated object 3 is housed inside.

A door 5 is provided in the front opening 4 of the heating chamber 2 so as to be openable and closable, and the portion of the door 5 corresponding to the opening 4 is composed of a transparent body 6 such as glass and a radio wave shielding body 7 made of wire mesh or the like. A peep window 8 is formed. An intake hole 9 is provided on the side surface of the heating chamber 2 for supplying air into the heating chamber, and an intake hole 12 provided at the rear of the main body 1 is driven by a fan 11 attached to a motor 10. The more sucked air is introduced into the heating chamber 2 along the intake guide 13 through the intake aperture 9, and is blown onto the viewing window 8. Almost all of the air introduced in this way passes through the exhaust hole 14 provided on the top surface of the heating chamber 2, and then passes through the main body 1, the top surface of the heating chamber 2, the exhaust guide 15, and 16
The air exits to an exhaust passage 17 formed by the air, and is exhausted through an exhaust hole 18 provided on the rear wall of the main body.

The exhaust hole 14 and the intake hole 9 constitute a part of the heating chamber 2, and are made of a plurality of holes that allow air to pass through but do not allow high frequency output to pass through, such as punched holes or wire mesh. The total exhaust opening area _S14 of the plurality of holes constituting the exhaust aperture 14 is the same as that of the plurality of holes constituting the corresponding intake aperture 9. It is set so that the total intake opening area is _S9 or more. The total exhaust opening area S ₁₄ and the total intake opening area S ₉ are:
If the respective aperture ratios per unit area are equal, S ₁₄ =a×b, S ₉ =c×d. Since the total intake opening area S ₉ is made equal to or less than the total exhaust opening area S ₁₄ in this way, the air supplied into the heating chamber 2 is smoothly discharged from the exhaust opening, so that the air pressure inside the heating chamber 2 is reduced. It is possible to prevent a large amount of air from escaping through the gap between the main body 1 and the door 5 due to the humidity becoming abnormally high, thereby enabling more accurate humidity detection. In addition, since air flows into the heating chamber 2 forcefully through the intake opening 9, an air flow can be created between the transparent body 6 of the viewing window 8 and the object to be heated 3, and the steam emitted from the object to be heated 3. It is also possible to prevent condensation on the transparent body 6 and clouding.

At one location in the exhaust path 17 between the exhaust opening 14 and the exhaust hole 18, there is a humidity sensor 19 whose individual resistance value changes depending on the humidity of the air. It is attached to the exhaust guide 15. Furthermore, an exhaust flow adjustment plate 20 is provided in the exhaust passage 17 at a position corresponding to the humidity sensor 19 and is spaced apart from both exhaust guides 15 and 16 by a predetermined distance. The water is configured to flow on both sides at a predetermined ratio.

In addition, the total exhaust opening area S ₁₄ of the exhaust opening portion 14 and the total exhaust opening area S ₁₈ of the exhaust holes 18 provided in the main body 1
The relationship between S 18 and S ₁₈ is set to be larger than S ₁₄ , and by doing so, the air containing the humidity to be detected that exits from the exhaust opening 14 to the exhaust passage 17 becomes stagnant. Quickly remove the main unit 1
Since fresh air is always supplied to the exhaust passage 17, the air containing the signal of the heating status of the heated object 3 smoothly reaches the humidity sensor 19, which increases the response speed and provides accurate It is very effective in detecting humidity.

The fan 11 is also configured to cool electrical components such as a high-frequency oscillator 21 such as a magnetron, and the air after cooling the high-frequency oscillator 21 passes through an air guide 22 provided on the side of the main body 1. The air intake port 13' of the intake guide 13 is located closer to the fan 11 than the exhaust side 21' of the high-frequency oscillator 21 so as to be directly discharged to the outside from the exhaust port 23 and not mixed with the air supplied into the heating chamber 2. It is mandatory. Note that the high frequency output is from the high frequency oscillator 21.
It is supplied into the heating chamber 2 via the waveguide 24.

In this embodiment, the configuration is explained in which some of the air in the heating chamber 2 escapes through the gap between the main body 1 and the door 5, but as shown in FIG. 4, when the door 5 is closed, the main body 1 and the door If a gasket 26 molded from a flexible resin material is provided on the outer circumferential side of the check groove 25 of the door 5 so that the gasket 5 is in close pneumatic contact with the door 5, air leakage can be prevented and humidity can be determined more accurately. Changes can be detected. Furthermore, if this gasket 26 is molded from a conductive resin material, it will be effective in preventing leakage of air and high frequency output.

Next, the operation will be described. The high frequency oscillator 21 is activated to heat the object 3 to be heated, and the temperature of the object 3 to be heated gradually rises. After a predetermined period of time, when the temperature approaches the boiling point, steam begins to come out violently.If we explain this with reference to Figure 3, from point O to point _T1 on the horizontal axis, that is, when the object to be heated 3 begins to be heated, it starts to boil. Until this point, the relative humidity of the air discharged from the exhaust aperture 14 gradually decreases as shown in FIG. This is because as the temperature of the heated object 3 rises, the air in the heating chamber 2 is warmed by the heated object 3, etc., and the temperature rises, but the humidity remains unchanged until the heated object 3 emits steam. This is because there is no factor to increase the relative humidity, and as a result, the relative humidity value gradually decreases. Then, when the heated object 3 is heated to near its boiling point, steam is rapidly released from the heated object 3, and as time passes from T ₁ to T ₂ to T ₃ , the relative humidity also changes to H ₁ , H ₂ , and It increases rapidly with _H3 . Since the humidity sensor 19 is an element whose specific resistance value changes with a change in relative humidity, the above-mentioned sudden increase in relative humidity, that is, a sudden increase in resistance value, for example between T ₁ and T ₂ detecting a sudden increase in , and inputting this signal to a suitable control circuit (not shown).
The circuit is configured to control the output of the high frequency oscillator 21 after a predetermined period of time.

Note that in the embodiment of the present invention, the humidity sensor 19 is used to detect the heating state of the object to be heated 3;
The present invention is not particularly limited to this, and it goes without saying that the effects of the present invention can be utilized even if changes in the temperature of the exhaust air that rises depending on the heating temperature of the heated object 3 are detected, and the present invention can be applied in various ways. It is possible.

Effects of the Invention As described above, the high frequency heating device of the present invention has the remarkable effects described below.

() It is possible to suppress variations in detection timing based on the specificity of radio wave heating.

In other words, when food is heated by radio waves, the entire food is not necessarily heated uniformly due to the diversity of the dielectric constant of the food and the uneven distribution of radio waves in the heating chamber, and there are parts that heat faster and parts that heat slower. So-called uneven heating occurs. If a sensor detects a signal such as water vapor caused by a localized boiling phenomenon in an area that heats up quickly, the heating ends even though the food as a whole is not fully cooked, which is the so-called premature cooking phenomenon. occurs.

However, in the present application, air is forcibly blown into the heating chamber by a propeller fan, so the air sent into the heating chamber agitates the air in the heating chamber, and therefore, the above-mentioned local parts are generated in the heating chamber. Even if steam is generated due to heating, it will be diluted by the agitation effect of this blower before leaving the heating chamber, so the airflow that reaches the detection means will suppress the signal caused by such local heating, and as a result, it will be detected quickly. It is possible to provide a microwave oven equipped with a highly reliable heating detection system that does not cause malfunctions such as burnouts.

() Furthermore, in the present application, since the total opening area of the exhaust holes made up of a plurality of openings provided in the main body is made larger than the total opening area of the exhaust openings of the heating chamber, (a) The air coming out of the opening passes through the exhaust guide and is smoothly exhausted from the exhaust hole of the main body, so the detection means inside this exhaust guide can quickly and accurately detect the degree of heating of the object to be heated in the heating chamber. (b) At the exhaust hole of the main body, the exhaust flow is detected from the exhaust hole at a moderate speed through multiple openings, so the inside of the exhaust guide is connected to the outside of the main body by this exhaust hole. will be isolated,
Therefore, it is possible to prevent the external environment around the exhaust hole on the outside of the main body from affecting the area around the detection means due to air diffusion, etc., thereby preventing the negative effect of erroneous operation. It is possible to provide a range.

[Brief explanation of drawings]

FIG. 1 is a front cross-sectional view of a high-frequency heating device showing one embodiment of the present invention, and FIG. 2 is a
3 is a graph showing the principle of operation in FIG. 1, and FIG. 4 is an enlarged sectional view of a main part of another embodiment of the present invention. 9...Intake opening portion, 11...Fan, 13...
Intake guide, 13'...Air intake port, 14...Exhaust hole, 19...Humidity sensor (detection means), 2
3...Exhaust port.

Claims (1)

[Claims] 1. A main body having a heating chamber for accommodating an object to be heated inside, a door provided in an opening that can be freely opened and closed for taking the object to be heated into and out of the heating chamber, and generating high-frequency output to be supplied into the heating chamber. A high-frequency oscillator, a fan that cools the high-frequency oscillator, etc., an intake aperture provided at a predetermined location in the heating chamber for introducing air driven by the fan into the heating chamber, and an intake aperture for introducing air driven by the fan into the heating chamber; An exhaust hole is provided in a part of the main body to exhaust the air exhausted from the heating chamber to the outside of the heating chamber. It has a detection means for detecting a physical change such as humidity of the air discharged from the hole, and an output control means for controlling a high frequency output based on a signal from the detection means, and the fan is constituted by a propeller fan, and the The exhaust opening portion and the exhaust hole are communicated with each other through an exhaust guide provided with the detection means therein, and the total opening area of the exhaust hole made up of a plurality of openings is larger than that of the exhaust hole portion. A high frequency heating device characterized by: