JPH07318067A - Reduced pressure high-frequency wave heating device - Google Patents

Abstract

PURPOSE:To execute a most adequate heating independently with respect to a kind and a weight of a material to be heated, by executing a control of a magnetron, on the basis of a detected value by a pressure sensor. CONSTITUTION:A reduced pressure high-frequency wave heating device 1 is provided with a closed vessel 3 wherein an accommodation and a setting of a material to be heated are possible, a magnetron 6 irradiating a microwave to the heated material in the closed vessel 3, a vacuum exhaust valve 11a and a vacuum pump 12 that decrease a pressure in the closed vessel 3, a pressure sensor detecting a pressure in the closed vessel 3, and a control section. And, the pressure sensor detects a pressure in the closed vessel that rises according to vapour generated from the heated material in a heating process, and the control section executes a control of the magnetron 6 and a heating of the heated material, on the basis of the heating time till an arrival to a predetermined vacuum degree.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decompression high-frequency heating device for performing microwave heating on an object to be heated under reduced pressure, and particularly to a depressurization capable of automating the heating regardless of the kind and weight of the object to be heated. The present invention relates to a high frequency heating device.

[0002]

2. Description of the Related Art Conventionally, in the case of thawing a frozen body which is an object to be heated, it has been performed by microwave heating under atmospheric pressure like a microwave oven. However, in some cases, the object to be heated is partially overheated due to uneven heating of the microwave, and the temperature becomes too high, so that a satisfactory thawing result cannot be obtained due to protein whitening and the like. As a method of preventing this partial temperature rise, a method of utilizing the fact that the object to be heated does not rise above the boiling temperature has been considered. This is called a decompression high-frequency heating device.By lowering the pressure inside a sealed container that contains the object to be heated using a decompression means such as a vacuum pump, the boiling temperature of water is lowered in response to the pressure. In the thaw of the object to be heated, partial overheating is prevented and rapid thaw at a predetermined temperature or lower is possible.

The structure of a conventional decompression high-frequency heating device will be described with reference to FIG.

A door 52 is rotatably supported at the front opening of the closed container 51 so as to be openable and closable. A magnetron 53, which is a microwave generator, is coupled to the closed container 51 by a waveguide 54. The exhaust port 55 provided on one wall surface of the closed container 51 communicates with the vacuum exhaust valve 56 and the vacuum release valve 5.
7. A vacuum pump 58 is arranged.

Next, the operation of the conventional decompression high-frequency heating device will be described.

An object 59 to be heated is housed inside the closed container 51. The air in the closed container 51 is discharged from the exhaust port 55 through the vacuum exhaust valve 56 to the outside of the closed container 51 by the vacuum pump 58. The pressure sensor 60 is arranged on one wall surface of the closed container 51 and detects the pressure in the closed container 51.
The control unit 61 controls the magnetron 53 to perform microwave heating for the set heating time. After that, the inside of the closed container 51 is returned to the atmospheric pressure by introducing the outside air into the closed container 51 from the exhaust port 55 through the vacuum opening valve 57.

[0007]

However, the optimum heating time according to the object to be heated varies depending on the type and weight of the object to be heated. Therefore, in order to set the optimum heating time according to the type and weight of the object to be heated, it is necessary to determine the type of the object to be heated or measure the weight, which is very complicated and difficult. It was It is also possible to use a humidity / gas sensor used in conventional microwave ovens as a means of detecting the type and weight of the object to be heated, but convection of air occurs in a depressurized closed container. Therefore, there is a problem that water vapor and gas generated from the object to be heated do not hit the humidity and gas sensor with high sensitivity, and accurate measurement results cannot be obtained.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to irradiate an object with microwaves in an optimum heating time without additionally installing new dedicated detecting means. It is the one.

[0009]

In order to achieve this object, a decompression high-frequency heating apparatus of the present invention comprises a closed container in which an object to be heated can be stored, a decompression means for decompressing the inside of the closed container, and the closed container. Microwave irradiation means for irradiating the object to be heated in the container with microwaves, pressure detection means for detecting the pressure in the closed container, and microwave irradiation means for irradiating the object to be heated with microwaves. It is provided with a time measuring means for measuring time, and a control means for controlling the power supply to the microwave irradiating means based on the detection value of the pressure detecting means and the measurement time of the time measuring means.

[0010]

In the decompression high-frequency heating apparatus of the present invention having the above structure, the object to be heated is placed in the closed container, and the inside of the closed container is depressurized by the depressurizing means. The microwave irradiating means irradiates the object to be heated in the closed container with microwaves, the pressure detecting means detects the pressure in the closed container, and the time measuring means applies the microwave irradiating means to the object to be heated. The microwave irradiation time is measured, and the control means controls the power supply to the microwave irradiation means based on the detection value of the pressure detection means and the measurement time of the timing means, and is optimal for the object to be heated. Heat well.

The optimum heating time of the object to be heated is determined by the water content of the object to be heated, and the amount of water vapor generated by heating the object to be heated is determined by the water content of the object to be heated. Therefore,
As in the present invention, if the microwave control means is controlled by the control means on the basis of the pressure rise due to the steam generated from the object to be heated by heating and the time until the pressure rise occurs, the type and weight of the object to be heated can be reduced. Regardless, it becomes possible to heat the object to be heated in an optimum time.

[0012]

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 1 showing an embodiment of the present invention. Here, FIG. 1 is a right side view of the reduced pressure high frequency heating apparatus 1 according to the present embodiment.

Inside the decompression high-frequency heating device 1, there is provided a hermetically-sealed container 3 for accommodating the object to be heated 2, and the hermetically-sealed container 3 is provided with a front opening 3a facing leftward in FIG. A door 4 is pivotally supported in the front opening 3a so as to be openable and closable. The object to be heated 2 is housed inside the closed container 3, and the inside of the closed container 3 is closed via a packing 5 arranged on the periphery of the door 4. The magnetron 6 as a microwave generator is coupled to the closed container 3 by a waveguide 7, and a plate-shaped partition such as crystallized glass having high radio wave transmission and high strength is provided in the opening 7a of the waveguide 7. A plate 8 is provided,
The partition plate 8 is sealed by a packing 9. Therefore, the airtightness of the closed container 3 is maintained. An exhaust port 10 for exhausting the air in the closed container 3 is provided on one wall surface 3b of the closed container 3, and the exhaust port 10 is provided with a vacuum exhaust valve 11a and a vacuum release valve 11b via an exhaust pipe 10a. A vacuum pump 12, which is a pressure reducing means, is connected to the vacuum exhaust valve 11a.

A pressure sensor 13 as a pressure detecting means is connected to one wall surface 3b of the closed container 3.

Further, a decompression high frequency heating device 1 above the door 4
A control unit 14 is provided on the front surface of the.

As shown in FIG. 2, the control unit 14 includes a CPU 15 for performing various kinds of arithmetic processing, and a RAM 16 for storing the vacuum degree based on the measured pressure detected by the pressure sensor 13, the heating time measured by the timer 18, and the like. , Decompression high frequency heating device 1
The ROM 17 stores a control program for the above, a correction time T2 described later, and the like, and a timer 18 that measures the heating time by the magnetron 6. In addition, the control unit 14
Is connected to the pressure sensor 13 via the detection circuit 19,
The driver 2 is connected to the magnetron 6, the driver 21 is connected to the vacuum pump 12, and the driver 22 is connected to the vacuum exhaust valve 11a.
3 is connected to the vacuum release valve 11b.

Next, the memory area of the RAM 16 will be described with reference to FIG.

The RAM 16 has a vacuum degree storage area 16a for storing a vacuum degree based on the pressure measured by the pressure sensor 13.
And the object 2 to be heated by the magnetron 6 measured by the timer
A heating time storage area 16b for storing the time of heating
Work area 16 for temporarily storing other data
c and are provided.

Next, the memory area of the ROM 16 will be described with reference to FIG.

The ROM 17 has a control program storage area 17 for storing a control program of the reduced pressure high frequency heating device 1.
a, a correction time storage area 17b for storing a later-described correction time T2, and a P1 table data storage area 17c.

Next, the operation of the decompression high-frequency heating apparatus 1 of the present embodiment having the above configuration will be described with reference to the flow chart of FIG. 5 and the time chart of FIG.

First, the object 2 to be heated is placed in the closed container 3, and the door 4 of the closed container 3 is closed. Then, the degree of vacuum P is set on the operation panel (not shown) on the front surface of the decompression high-frequency heating device 1, and the start switch (not shown) is pressed (S1). In response to this, the control unit 14 closes the vacuum release valve 11b via the driver 23. At the same time, the vacuum exhaust valve 11a is opened via the driver 22, and the vacuum pump 12 is operated via the driver 21 to start depressurizing the closed container 3 (S2). At the same time when the depressurization is started, power supply to the magnetron 6 is started to irradiate the object to be heated 2 in the closed container 3 with microwaves to start heating (S2). Here, at the same time when the power supply to the magnetron 6 is started, the heating time is measured by the timer 18 and the pressure sensor 1
The pressure measurement by 3 is also started (S2). Here, the detection value by the pressure sensor 13 is converted into a vacuum degree by the detection circuit 19.

Further, the degree of vacuum P corresponding to the degree of vacuum P set from the P1 table data storage area 17c of the ROM 17
The value of 1 is read out and stored in the work area 16c of the RAM 16. Here, the degree of vacuum P1 is lower than the set degree of vacuum P (higher value as pressure), and the optimum value obtained by experiment is stored according to the value of P.

Next, when the pressure in the closed container 3 is reduced and reaches a set predetermined vacuum degree P (S3, YES),
The vacuum exhaust valve 11a is closed and the depressurization operation in the closed container 3 is stopped (S4). In this case, the vacuum pump 12 may be stopped. Furthermore, by irradiating the object to be heated 2 in the closed container 3 with microwaves and continuing heating, the pressure in the closed container 3 is increased by the steam generated from the object 2 to be heated.
Here, when the vacuum degree based on the pressure detected by the pressure sensor 13 reaches the value of P1 stored in the work area 16c of the RAM 16 (S5, YES), the heating time T1 measured by turning off the timer is set to the work area 16c of the RAM 16. (S6).

Next, the correction time T2 corresponding to T1 stored in the work area 16c is read from the correction time storage area 17b of the ROM 17 and the work area 1 of the RAM 16 is read.
It is stored in 6c (S7). This correction time T2 is set to a constant ratio with respect to the initial heating time T1, and this ratio varies depending on the microwave output, the degree of vacuum, etc.
1 is defined in the range of approximately 20 to 40%, and is stored in the correction time T2 storage area of the ROM 17.

Next, the vacuum exhaust valve 11a is opened to start depressurizing the closed container 2 by the vacuum pump 12, and the timer 18 is reset and turned on to measure the additional heating time (S8). At this time, the time measured by the timer 18 is T2.
Until (S9, NO), the pressure of the closed container 3 is controlled (S10, S11, S12, S13). In particular,
If the degree of vacuum based on the detection value of the pressure sensor becomes P (S1
0, YES), and the vacuum exhaust valve 11a is closed (S11).
After that, when the pressure of the closed container 3 is increased by the steam generated from the object to be heated 2 and the vacuum degree becomes P1 (S12.Y
ES), the vacuum exhaust valve 11a is opened, and the decompression of the closed container 3 is restarted by the vacuum pump 12 (S13).

After that, the time measured by the timer 18 is RA
When the correction time T2 stored in the work area 16 of M16 comes (YES in S9), the magnetron 6 is turned off, the vacuum release valve 11b is opened to return the inside of the closed container 3 to atmospheric pressure, and the vacuum pump 12 is turned off. At the same time, the timer 18 is turned off and reset (S14). And
The user opens the door 4 and takes out the object to be heated 2.

Here, the reduced pressure high frequency heating apparatus 1 of this embodiment is used.
The case where frozen sushi is thawed will be described as an example of the experimental result according to.

Frozen sushi containing 8 cans (about 300 g) was thawed at a microwave output of 400 W of the magnetron 6 in a vacuum state of a vacuum degree of 30 Torr (P) in the closed container 3, and as a result, 140 seconds (T1) from the start of heating. ), P1 (35 Torr) is reached, and the remaining heating time (T2) is 35 seconds (14
0% is 25%) and the total heating time (T) is 17
It's 0 seconds.

In this embodiment, the power supply to the magnetron 6 is started at the same time when the vacuum pump 12 starts the pressure reduction, but the power supply to the magnetron 6 is started after the vacuum pump 12 finishes the pressure reduction to the vacuum degree P. Good.

As described above, in the decompression high-frequency heating device 1 of this embodiment, the pressure sensor 13 and the detection circuit 19 are being heated.
The degree of vacuum in the closed container 3 is measured based on the signal from and the heating time is measured by the timer 19. Then, after the pressure in the closed container 3 reaches the set vacuum degree P, the pressure in the closed container 3 increases due to the steam generated from the object to be heated 2 by heating with the microwave, so that the predetermined vacuum degree P1 is reached.
Then, based on the time T1 from the start of heating measured by the timer 18 to the degree of vacuum P1, the control means 14
Controls the magnetron 6 at the correction time T2 to perform additional heating. Therefore, the object to be heated 2 is heated in the optimum heating time regardless of its type and weight.

The decompression high-frequency heating apparatus 1 of this embodiment heats the object to be heated 2 based on the pressure increase due to the steam generated from the object 2 to be heated and the heating time until the pressure increase is detected. That is, it becomes possible to perform heating in an appropriate heating time according to the water content of the object to be heated.

[0034]

As is apparent from the above description, according to the decompression high-frequency heating apparatus of the present invention, the object to be heated is automatically microwaved in the optimum heating time regardless of the kind and weight of the object to be heated. It becomes possible to heat by. Therefore, it is possible to realize automation of heating under reduced pressure without additionally installing a detection unit for detecting weight and the like.

[Brief description of drawings]

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

FIG. 2 is a block diagram of a control unit of the reduced pressure high frequency heating apparatus according to the embodiment of the present invention.

FIG. 3 is an area diagram of a memory of a RAM of a control unit of the decompression high-frequency heating device which is an embodiment of the present invention.

FIG. 4 is an area diagram of a ROM memory of a control unit of the decompression high-frequency heating apparatus which is an embodiment of the present invention.

FIG. 5 is a flow chart of control of a reduced pressure high frequency heating apparatus that is an embodiment of the present invention.

FIG. 6 is a time chart of the pressure transition in the closed container and the operation of each component of the decompression high-frequency heating device which is an embodiment of the present invention.

FIG. 7 is a structural diagram of a conventional decompression high-frequency heating device.

[Explanation of symbols]

 3 Airtight Container 6 Magnetron 11a Vacuum Exhaust Valve 11b Vacuum Release Valve 12 Vacuum Pump 13 Pressure Sensor 14 Controller 19 Detection Circuit 20 Driver 21 Driver 22 Driver 23 Driver

Claims (3)

[Claims] 1. A hermetically sealed container in which an object to be heated can be stored, a decompression means for decompressing the inside of the hermetically sealed container, a microwave irradiating means for irradiating a material to be heated in the hermetically sealed container with a microwave, and the hermetically sealed container. A pressure detecting means for detecting the pressure in the container, a time measuring means for measuring the time for irradiating the object to be heated with microwaves by the microwave irradiating means, a detection value of the pressure detecting means and the time measuring means A reduced-pressure high-frequency heating device, comprising: a control unit that controls power supply to the microwave irradiation unit based on a measurement time. 2. The reduced pressure according to claim 1, wherein the pressure detection unit detects a pressure increase due to water vapor generated from the object to be heated by heating the object to be heated by the microwave irradiation unit. High frequency heating device. 3. The object to be heated by the microwave irradiating means, wherein the pressure detecting means detects a predetermined depressurization value after the microwave irradiating by the microwave irradiating means, which is timed by the time measuring means, is started. 2. The reduced pressure high frequency heating device according to claim 1, wherein the microwave irradiation means is controlled based on a time until the pressure rises to a predetermined pressure value due to the steam generated by heating to the microwave.