JPH06129649A - Pressure reduction high frequency heating device - Google Patents

Abstract

PURPOSE:To detect the type of an article to be heated without providing a special device as a detection means of the article to be heated by using a pressure sensor required to detect pressures in an enclosed vessel not only as a means primarily required to control a vacuum pump but also as a heated article detection means which detects the type of the article to be heated. CONSTITUTION:When pressure reduction starts in an enclosed vessel, a pressure sensor measures changes in the enclosed vessel, thereby detecting the size of an article to be heated and executing microwave heating only for a heating time calculated in conformity with the detected size. The type of the article to be heated is detected from changes in a pressure rise in the enclosed vessel and the calculated heating time is corrected so that microwave heating may be executed for an optimum heating time set for the article to be heated. After the type of the article to be heated is detected, the pressure sensor transmits a signal to control a vacuum pump or a vacuum exhaust valve so that the degree of vacuum in the enclosed vessel may be maintained substantially at a constant value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduced-pressure high-frequency heating device for performing microwave heating under reduced pressure, and more particularly to automation of the heating.

[0002]

2. Description of the Related Art Conventionally, in automation of heating in a microwave under atmospheric pressure, as a means for detecting an object to be heated, a weight sensor for detecting the weight, moisture and gas emitted from the object to be heated, etc. A humidity / gas sensor for detection and an infrared sensor for detecting the surface temperature of the object to be heated were used. Then, using the information on the object to be heated detected by the sensor or the like, an optimum method of heating the object to be heated such as heating time and microwave output is calculated and controlled by a microcomputer or the like.

[0003]

By the way, the pressure detecting means in the high-frequency heating device which performs microwave heating under reduced pressure detects the pressure in the closed container and makes the inside of the closed container substantially constant. It was only used for things and was not specifically used for other uses. Further, as a type detecting device such as a humidity sensor as a means for detecting the type of the heated object, when performing heating under reduced pressure, since convection of air does not occur in the closed container, water vapor generated from the heated object However, the humidity sensor does not hit the sensor with high sensitivity and accurate measurement cannot be performed. Even if a fan is installed so that air convection occurs in the closed container to improve the measurement accuracy of the humidity sensor, it is structurally difficult to install the fan etc. in order to maintain the closed degree of the closed container. It was also unreasonable financially.

The present invention has been made to solve the above-mentioned problems, and the type of the object to be heated can be obtained without additionally installing a new dedicated detecting means for detecting the type of the object to be heated. It is made possible to detect.

[0005]

In order to achieve this object, in the decompression high-frequency heating apparatus of the present invention, the pressure detecting means for detecting a predetermined pressure in the closed container has a pressure in the closed container during heating by microwaves. It also has a function as an object-to-be-detected means for detecting the type of the object to be heated from the change.

[0006]

In the decompression high-frequency heating device of the present invention having the above-mentioned structure, the decompression device is controlled while using the pressure detecting means to decompress the inside of the closed container to a predetermined pressure, and the microwave is generated after the pressure is reduced to a predetermined pressure. In the heating process of the object to be heated by the device, the type of the object to be heated in the closed container is detected by the pressure detection means that functions as the object to be heated detection means, and the power is supplied to the microwave generator according to the type of the object to be heated. Control and heat the object to be heated automatically.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a reduced pressure high frequency heating apparatus showing an embodiment of the present invention.

First, in FIG. 1, a door 2 is rotatably supported by an opening in a front surface of a closed container 1 so as to be openable and closable. The object 3 to be heated is housed inside the closed container 1, and the inside of the closed container 1 is sealed via a packing 4 arranged on the periphery of the door 2. The magnetron 5, which is a microwave generator, is connected to the closed container 1 by a waveguide 6, and the opening has a plate-shaped partition plate 7 such as crystallized glass having high radio wave permeability and high hardness, which is sealed with packing or the like. It has been stopped. The air in the closed container 1 is exhausted from a vacuum pump 10 as a pressure reducing device through an exhaust port 8 provided on one wall surface of the closed container 1 through a vacuum exhaust valve 9.

The pressure sensor 11, which is a pressure detecting means, is disposed on one wall surface of the closed container 1 and is also used as a heated object detecting means. A control unit (control means) 12 including a microcomputer or the like detects a signal from the pressure sensor 11 and a detection circuit 1
Monitor via 3. Then, power supply and operation to the magnetron 5, the vacuum pump 10, the vacuum exhaust valve 9, the vacuum release valve 14, etc. are controlled via the drivers 15, 16, 17, and 18, respectively. Further, in order to return the inside of the closed container 1 to the atmospheric pressure after the decompression and the heating, the outside air is introduced into the closed container 1 through the vacuum release valve 14.

Next, regarding the operation, the pressure change in the closed container 1 during depressurization and heating in FIG. 2, the pressure change in the closed container 1 during depressurization and heating and the time chart of the depressurized high frequency heating device will be described. It demonstrates using.

First, in FIG. 3, the object 3 to be heated is placed in the closed container 1, and the door 2 of the closed container 1 is closed. Then, the degree of vacuum P is set on the operation panel (not shown) on the front of the apparatus, and the start switch (not shown) is pressed. In response to this, the control unit 12 releases the vacuum exhaust valve 9 provided in the communicating portion of the closed container 1 and operates the vacuum pump 10 with the vacuum release valve 14 closed, whereby the inside of the closed container 1 is closed. Start depressurizing. Simultaneously with the start of depressurization, the timer 19 incorporated in the control unit 12 is activated. The timer 19
The pressure in the sealed container 1 by measuring the time T ₁ of the up is reduced to a predetermined pressure P _1, it stops the operation of the timer 19 when it reaches a predetermined pressure P _1.

Here, in FIG. 2, the amount of air discharged from the closed container 1 to the outside by the vacuum pump 10 during the depressurization and the size (volume) of the object 3 to be heated stored in the closed container 1 are as follows. , Inversely related. Due to this relationship, when the air in the closed container 1 is discharged by the constant exhaust force of the vacuum pump 10, the pressure in the closed container 1 is reduced faster as the size (volume) of the object to be heated 3 increases, and the predetermined pressure is reduced. The pressure P ₁ is reached. Utilizing this fact, the control unit 12
Is the time T ₁ and the object to be heated 3 which are obtained in advance by experiments or the like.
The size of the object to be heated 3 is calculated using a formula expressing the relationship with the size of the object to be heated, or a reference table of the size of the object to be heated 3 and the time T ₁ stored in the memory in advance is referred to,
The size of the object 3 to be heated is calculated according to the time T ₁ .

After the pressure in the closed container 1 is further reduced from P ₁ and reaches a predetermined vacuum degree P, the vacuum exhaust valve 9 is closed, the vacuum pump 10 is stopped, and a series of depressurization processes are completed.

Next, the control unit 12 calculates the heating time T of the object to be heated 3 based on the size of the object to be heated 3 determined during the depressurization. Then, the heating time T is set to the control unit 12
Then, the countdown of the heating time T is started. Further, the power supply to the magnetron 5 is started, the object 3 to be heated in the closed container 1 is irradiated with microwaves, and heating is started.

When heating is started, the pressure in the closed container 1 gradually rises due to water vapor or the like generated from the object 3 to be heated, but at the same time as the heating is started, the timer 20 built in the control unit 12 is started to set a predetermined value. The time T ₂ until the atmospheric pressure in the closed container 1 rises to the degree of vacuum P ₂ is measured.

Here, the water content generally contained in food is
It depends on the type of meat, fish, vegetables, etc. In FIG. 2, if the object 3 to be heated is irradiated with a certain microwave to be heated, the amount of water vapor generated varies depending on the type of the object 3 to be heated and thus the amount of water. That is, under reduced pressure,
Since the speed at which the pressure in the closed container 1 rises varies depending on the amount of water vapor generated from the object to be heated 3 when the object to be heated 3 is heated, the object to be heated 3 can be measured by measuring the pressure change.
The type of can be determined.

Therefore, the control unit 12 controls the inside of the closed container 1 to P
To stop the timer 20 When increased from ₁ to a predetermined degree of vacuum P _2, the based on the data indicating the time T ₂ has been determined in advance by experiments or the like from the time T ₂ the correspondence between the type of the object to be heated 3 Find the type of heating object 3.

Further, the heating time T already set from the size of the object to be heated 3 is added or reduced by a correction time determined by the type of the object to be heated 3 to obtain the size of the object to be heated 3 and The heating time is corrected so that optimum heating control can be performed for each type, and the final heating time T ′ is reset.

Further, during heating, the control unit 12 heats through the drivers 17 and 16 so that the pressure in the closed container 1 is maintained at a predetermined vacuum degree P based on the signals from the pressure sensor 11 and the detection circuit 13. The vacuum exhaust valve 9 and the vacuum pump 10 are controlled until the above is completed.

When the heating time reaches the set time, the microwave heating process is completed, the vacuum release valve 14 is opened, the closed container 1 is returned to atmospheric pressure, and the door 2 is opened.
To open the object 3 to be heated.

In the above embodiment, the pressure sensor 11, which is the pressure detecting means, also functions as a means for detecting the size of the object 3 to be heated, so that it is dedicated to detect the size of the object 3 to be heated. It is not necessary to separately provide the detection means of.

When the size of the object 3 to be heated is detected, in the above embodiment, the time T ₁ from the start of depressurization to the depressurization to a predetermined pressure is measured and the pressure change in the closed container 1 is detected to detect the size. Although the size of the heating object 3 is detected, for example, the pressure sensor 11 measures the pressure after a certain period of time from the time when the vacuum pump 10 starts the pressure reduction, or the pressure sensor 11 starts when the pressure reduction starts. Closed container 1 detected by
The time change amount (ΔP / Δt) of the internal pressure may be measured, the pressure change in the closed container 1 may be detected, and the size of the object 3 to be heated may be detected to obtain the heating time T. . This also applies to the case of detecting the type of the object to be heated 3.

Further, in the above embodiment, the size of the object to be heated 3 is detected by measuring the pressure change, the heating time T is calculated, and then the pressure due to the steam from the object to be heated 3 during heating is calculated. The type of the object 3 to be heated was detected from the change and the heating time T was corrected.
Depending on the size and type of the microwave output is set to be the optimum output, or reset, or both the microwave output and the time are set to be optimum,
Alternatively, the heating may be controlled by resetting.

[0025]

As is apparent from the above description, according to the decompression high frequency heating apparatus of the present invention, the pressure detecting means necessary for detecting the predetermined pressure in the closed container is heated by the pressure change in the closed container. Since it is also used as a heated object detection means for detecting the type of object, without additionally installing a new dedicated detection means for detecting the type of heated object,
Automation of heating under reduced pressure can be realized.

[Brief description of drawings]

FIG. 1 is a schematic view of a reduced-pressure high-frequency heating device showing an embodiment of the present invention.

FIG. 2 is a diagram showing changes in pressure inside a closed container during depressurization and heating.

FIG. 3 is a time chart diagram of a pressure transition in a closed container during decompression and heating and a decompression high-frequency heating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Airtight container 3 Object to be heated 5 Magnetron (microwave generator) 10 Vacuum pump (pressure reducing means) 11 Pressure sensor (pressure detecting means, object to be heated detecting means) 12 Control unit (controlling means)

Claims (2)

[Claims] 1. A closed container capable of storing an object to be heated, a microwave generator for irradiating the object to be heated in the closed container with microwaves, a decompression means for decompressing the inside of the closed container, and a predetermined pressure. With a pressure detecting means for detecting, further in the heating process to the object to be heated by the microwave generator under reduced pressure, the pressure detecting means is also used as the object to be heated detecting means for detecting the type of the object to be heated, A decompression high-frequency heating apparatus comprising: a control unit that controls power supply to a microwave generator based on the type of an object to be heated detected by the object to be heated detection unit. 2. The control means terminates the pressure reduction to a predetermined pressure by the pressure reduction means, and when the pressure in the closed container rises due to the steam generated from the object to be heated by the heating by the microwave generator, the pressure change. The decompression high-frequency heating device according to claim 1, wherein the type of the object to be heated is detected from the above.