JPH06101847A - High frequency heating device - Google Patents

Abstract

PURPOSE:To prevent a time required for defreezing from being increased at a rate higher than a weight increase ratio when a large food material is defrozen, in a high frequency heating device having a function to defreeze a frozen food by means of a high frequency. CONSTITUTION:A heat absorbing means 15 to effect cooling of air in a heating chamber 4 is arranged in a ventilating duct 17 through which air is fed in the heating chamber 4. Further, an operation time of a device is divided in a multistage, and temperature in the heating chamber 4 is controlled by means of a high frequency output and an oscillating time in each stage and through operation of the heat absorbing means 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency heating device having a function of thawing frozen foods using high frequency waves.

[0002]

2. Description of the Related Art In recent years, with the widespread use of frozen foods, there has been a demand for thawing these foods for a short time, and a thawing method using a high-frequency heating device represented by a so-called microwave oven has been put into practical use. There is.

In general, as a thawing method of this kind, a method of changing the degree of application of a high frequency to a cooked product to several stages according to the passage of time is adopted. Japanese Patent Fair 2-61
The configuration as shown in Japanese Patent Publication No. 6 is one example. The configuration will be described below with reference to FIGS. 4 and 5.

As shown in FIG. 4, the high frequency generated by the high frequency oscillator 1 is guided to the heating chamber 4 by the waveguide 2 to heat the food 5. This high-frequency oscillator 1 responds to the user's operation.
Further, based on the input of information obtained through an external circuit, the microcomputer is controlled by a microcomputer (hereinafter referred to as a microcomputer) that controls the external circuit based on the analysis and calculation of each information and the result thereof. Particularly, in this example, the weight of the cooked food 5 is dealt with by connecting and disconnecting the relay and the high-voltage switch.
As shown in, time T1, time T2, time T3, time T
4, five times Tn in the order of time T5 (n = 1, 2, 3,
4, 5) each high frequency output Pn (n = 1, 2, 3,
4, 5) is controlled to enhance the effect of carry-over heating that occurs inside the cooking product 5, thereby making the device free from uneven thawing in a short time. Reference numeral 3 in the figure is an antenna.

[0005]

However, with the diversification of frozen foods, when thawing larger foods 5,
If you try to thaw evenly in this type of heating device,
It was found that the high frequency output at each time Tn had to be set lower. That is, as shown in the Auslegeschrift, the absorption amount Pr of the high frequency output of the center of the food 5 in the surface position Distance r from the food 5 is given by the formula Pr = Poε ^-fr.

Po: High frequency absorption amount on the surface f: Constant of simple increase Therefore, the high frequency absorption amount Pr at the center when the thickness of the cooked food 5 is doubled is ε in proportion to the absorption amount Po on the surface portion. ^{-It will be} doubled, the rise value of the internal temperature will decrease by that much, and the difference between the surface temperature and the internal temperature will increase. When the surface temperature becomes high, the finished state of the cooked product 5 is not preferable, so that the thickness of the cooked product 5 is increased and the cooked product 5 is eventually thickened.
The amount of high-frequency energy per unit surface area decreases and the total amount of high-frequency energy that can be applied to the surface increases, but the high-frequency output at each heating time must be relatively suppressed, and the extra amount is required for thawing. It has been found that it takes time, and in the end, when thawing with the homogenized cooked product 5, the thawing time when the amount is doubled requires double or more.

The present invention is intended to solve the above problems, and it is a first object of the present invention to prevent the thawing time of cooked food from becoming longer than the weight increase rate.

Further, in the conventional method, if the cooked food is left in the heating chamber after the thawing operation is completed, the temperature of the cooked food approaches the temperature of the heating chamber which is equal to or higher than room temperature, resulting in an unsatisfactory finish.

A second object of the present invention is to keep the finished state of the cooked product constant. Furthermore, in recent years, efficient use of kitchen rooms has been demanded.

A third object of the present invention is to minimize the space occupied by the device.

[0011]

In order to achieve the first object of the present invention, means for blowing low temperature air into the heating chamber to keep the temperature in the heating chamber within a set range is provided. During the decompression operation, according to the preset program,
The high frequency is applied while preventing the surface temperature of the cooked food in the heating chamber from rising above a certain level.

Further, in order to achieve the second object, the temperature control of the heating chamber is continued until the food is taken out after the thawing operation is completed.

Further, in order to achieve the above third object,
A device for controlling the flow of air in the device is provided so that the defrosting operation and the heating operation can be selectively performed in the same device.

[0014]

According to the present invention, in the above structure, by cooling the temperature in the heating chamber by blowing cold air into the heating chamber at the same time for a certain period while applying high-frequency energy to the food.
By cooling the surface of the cooked food and performing the defrosting operation while preventing overheating of this area, the high-frequency output at each heating time is set higher than in the past, and the cooked food is thawed in a shorter time. It was done.

Further, by continuously controlling the temperature of the heating chamber until the food is taken out, the temperature of the food which is partially different due to the application of the high frequency approaches the temperature of the heating chamber which is entirely controlled. , A more uniform finish is obtained and the temperature is maintained at the set temperature.

Further, the air blown into the heating chamber is opened and closed by opening and closing a shutter provided in the air passage.
You can circulate selectively to control the temperature below normal temperature,
Ventilation of the heating chamber can be performed, so that the food can be thawed and heated selectively.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. 1 and 2 show the high frequency heating apparatus of this embodiment. The same components as those in the conventional example are designated by the same reference numerals.

As shown in FIG. 1, the heating chamber 4 and the high-frequency oscillator 1 are coupled in a high frequency manner by a metal waveguide 2 and an antenna 3, and the high frequency oscillated from the high-frequency oscillator 1 irradiates the inside of the heating chamber 4. Then, the food 5 is dielectrically heated. The high-frequency oscillator 1 is cooled by the blower fan 6, and the air sent out cools the high-frequency oscillator 1 and then passes through the exhaust guide 7 and is exhausted to the outside of the heating device main body. In this embodiment, in order to heat the cooked food 5 more uniformly, two sets of the high frequency oscillator 1 and the blower fan 6 for cooling the same, the waveguide 2 and the antenna 3 are provided, and the heating chamber 4 is provided with a high frequency. An antenna 3 for irradiating is provided on each of the upper wall 8 and the bottom wall 9 forming the heating chamber 4. Reference numeral 14 is a door for moving the cooking product 5 in and out of the heating chamber 4. Also, 1
Reference numeral 0 is a control panel, and as shown in FIG. 2, a keyboard 12 having a plurality of keypads 11 for the user to set the heating output, heating time, and heating mode.
And a display tube 13 for displaying these setting states is incorporated.

As shown in FIG. 1, a cooling device for cooling the air in the heating chamber 4 is provided outside the heating chamber 4, and the cooling device is constructed as follows. ing. That is, the refrigerant vaporizes in the evaporator 15, and at this time absorbs the heat of the air passing through the evaporator 15,
The evaporator 15 has a structure in which a plurality of metal fins 16 are fixed around a thin tube for guiding the refrigerant, and the heating chamber upper wall 8 is provided in a ventilation duct 17 through which air for ventilating the heating chamber 4 is passed. Blow-out port 18 consisting of a group of small holes provided in a part of the
It is located near. The air sent from the ventilation fan 19 provided in the main body absorbs heat while passing between the plurality of metal fins 16 and is blown into the heating chamber 4.

Reference numeral 20 denotes a compressor, which has a structure in which the vaporized refrigerant is compressed and sent to the condenser 21 as a high temperature and high pressure gas. The compressor 20 is rotationally driven by a compressor motor 22. The condenser 21 radiates the heat of the refrigerant into the air and liquefies it. The condenser 21 is provided in an intake air passage provided between the blower fan 6 and an intake port 23 having a large number of small holes on the front surface of the main body, and a cooling fin 24 around a narrow tube for guiding a refrigerant is used to blow the blower. While the fan 6 is rotating, it is cooled by the movement of the air that is taken in, and heat is efficiently dissipated. The pressure of the cooled refrigerant further decreases as it passes through the narrow tube, is guided to the evaporator 15, and is vaporized again to absorb the heat of the air passing through the evaporator 15.

Further, a part of the rear wall 25 of the heating chamber is provided with an outlet 26 for the air introduced into the heating chamber 4 consisting of a group of small holes, and the air ventilated in the chamber is Outlet 2
6 is discharged from the main body through the exhaust duct 27 connecting the outside of the main body and the discharge port 26. Provided outside the heating chamber of the discharge port 26 is an electromagnetic shutter 28 having a structure in which the discharge port 26 is opened by energizing and closing the discharge port 26 in a non-energized state in response to the movement of the plunger S ₁ of the solenoid. And heating room 4
Ventilation inside can be selectively performed by an electric signal. FIG. 1 shows that the electromagnetic shutter 28 is in a non-energized state. Further, the ventilation fan 1 for supplying the air blown into the heating chamber 4 through the ventilation duct 17 described above.
9 is provided in the body.

The outlet of the ventilation fan 19 is connected to the ventilation duct 17, but the intake portion 29 is provided with a duct 32 having an electromagnetic shutter 31 for opening and closing the shutter in response to the movement of the solenoid plunger S _2. Is provided, and the other end of the duct 32 is connected to a circulation port 33 formed by a group of small holes provided in a part of the rear wall 25 of the heating chamber. The electromagnetic shutter 31 closes the circulation port 33 in the non-energized state, and is configured to supply the air sucked through the main body intake port 23 to the air intake part 29. The air that has passed through the heating chamber 4 is sucked again. FIG. 1 shows that the electromagnetic shutter 31 is in the energized state.

Further, a convex portion 34 having a group of small holes 35 is provided inward of the heating chamber 4 in a part of the heating chamber 4, and the thermistor 36 is provided inside the convex portion 34. Has been installed.

In the present embodiment, the two electromagnetic shutters 28 and 31 are opened and closed by the plungers S ₁ and S ₂ of the solenoid, respectively. In another embodiment, the shaft obtained by decelerating the rotation of the motor. The opening and closing may be performed by turning the output.

The control circuit of this device, as shown in FIG.
It is connected to the main power supply of AC 50/60 Hz via the main switch 37. Similar to the conventional example, the control device 38 has a microcomputer 4 that performs an operation according to a predetermined program when a predetermined voltage is applied from the driving power supply 39.
Based on 0, an input terminal unit 41 that takes in various control signals, an arithmetic unit that analyzes and arithmetically operates the input signals, a memory that stores programs and data, and an external circuit based on the obtained arithmetic result. The output terminal unit 42 outputs a control signal for controlling the.

Keypad 1 for setting heating conditions
1, a door signal switch 43 indicating the open / closed state of the door 14, a thermistor 36 for converting the temperature in the heating chamber 4 into an electric resistance
The signal line of is connected to the input terminal portion 41. Display tube 1 for displaying program status, heating data, and heating progress
3. Triac 4 for controlling oscillation of high frequency oscillator 1
4 and 45, the gate signal circuit of the triac 46 that controls the rotation of the drive motor 22 of the compressor 20, and the relay 4 that controls the motor 47 that drives the ventilation fan 19.
8, one end of each coil of the relay 50 for controlling the motor 49 for driving the blower fan 6, the relay 51 for controlling the opening / closing operation of the electromagnetic shutter 28, and the relay 52 for controlling the opening / closing operation of the electromagnetic shutter 31 has the output terminal portion 4
Connected to 2.

The driving power supplies 53 and 54 of the high frequency oscillator 1 and the triacs 44 and 45, and the motor 22 and the triac 46 that drive the compressor 20 are connected in series and connected to the main power supply AC. Further, a door switch 55 that cuts off power supply when the door 14 is opened is also connected in series to the driving power supplies 53 and 54 of the high frequency oscillator 1. Motor 49 and relay 50, motor 47 and relay 48, electromagnetic shutter 28 and relay 51, electromagnetic shutter 31 and relay 52
The respective output contacts of are connected in series.

The microcomputer 40 has a program capable of selecting a high frequency output for performing a defrosting operation by repeatedly pressing the defrosting key of the keypad 11. When pressed once, the triacs 44 and 45 continue to be turned on during the set time, the high frequency continues to oscillate, and the high frequency output is 1
It becomes 400W. When pressed twice or more, the oscillating time of the high frequency oscillator 1 changes within a certain time according to the number of times the button is pressed,
The average value of the high frequency output is changed. Also,
When the temperature key is pressed, the resistance value set in advance corresponding to the number of times the temperature key is pressed is compared with the resistance value of the thermistor 36 provided in the heating chamber, and the triac 46 is turned on until it becomes equal to the set value, and the compressor 20 By energizing the compressor motor 22 for driving, the program has a program capable of arbitrarily setting the ambient temperature in the heating chamber 4. Table 1 shows the relationship between the number of times each key of the keypad 11 is pressed and the high frequency output and the temperature in the heating chamber.

[0029]

[Table 1]

The operation of the above configuration will be described. When the user turns on the main switch 37, the controller 38 is energized to enable the operation. When performing the defrosting operation, the user presses the keypad 11 on the keyboard 12 to set desired defrosting conditions. Press the decompress key and then the output key to set the desired high frequency output. Next, the temperature key is pressed to set the temperature in the heating chamber 4. Further, the application time of the high frequency output and the temperature is set by pressing the number keys.
In the present embodiment, as shown in FIG. 3, the thawing operation is divided into three stages of time for raising the temperature of ice, time for accelerating the thawing, and time for uniformly thawing the thawed state. Set the settings for the entire decompression operation time, for example,
The first stage is high output, heating chamber temperature +7 ℃, heating time 10
Minute, second stage is medium output, heating chamber temperature ± 0 ° C, heating time 3
At 0 minutes, the third stage is set in three stages such as weak output, heating chamber temperature -2 ° C, and heating time 60 minutes. The microcomputer 40 temporarily stores the set heating conditions in the storage circuit, and when the user presses the start key, the triacs and relays connected to the output terminal section 42 are controlled according to the set conditions.

When this device is used as a heating device,
After pressing the heating key, simply set the high frequency output and heating time without pressing the temperature key. In this case, the cooling function does not operate and the temperature inside the heating chamber 4 is not controlled.

FIG. 3 shows each output control pattern of the control device for each operation. The triacs 44 and 45 which control the oscillation of the high frequency oscillator 1 repeat the intermittent operation according to the setting during the defrosting operation. Triac 4 for controlling rotation of compressor motor 22 that drives compressor 20
In accordance with the set temperature, 6 is energized when the temperature in the heating chamber 4 is higher, and shuts off when the temperature is lower, and the drive of the compressor 20 is interrupted to keep the temperature in the heating chamber 4 at the set value. When the thawing condition is set during the thawing operation and the door 14 is opened to install the cooked food 5 in the heating chamber 4, the operation is started to reach the temperature set in the first stage. After the thawing is completed, the compressor 20 is intermittently operated so as to maintain the temperature set in the third stage, and the operation is repeated until the door 14 is opened to take out the cooked food 5 from the heating chamber 4. Since the motor 47 for driving the ventilation fan 19 installs the cooked food 5 in the heating chamber 4 by the user, the motor 47 starts rotating when the door 14 is opened and takes out the cooked food 5 from the heating chamber 4 after thawing or heating is completed. After opening the door 14, the rotation is stopped after a certain period of time. The motor 49 for driving the blower fan 6 also starts to rotate when the door 14 is opened, and after the thawing and heating are completed, the door 14 is opened to take out the cooked food 5 from the heating chamber 4 and then the rotation is stopped after a certain time has elapsed.

The electromagnetic shutter 28 closes the discharge port 26 during the thawing operation, and immediately after the thawing operation is finished, the door 14 is opened, and the discharge port 26 is opened only while the ventilation fan 19 is rotating to prepare for the next operation. During the heating operation, while the ventilation fan 19 is rotating, the exhaust port 26 is opened to promote ventilation in the heating chamber 4.
The electromagnetic shutter 31 has the circulation port 3 at least during the thawing operation.
3, the ventilation fan 19 draws in the air in the heating chamber 4,
The discharged air is guided to the evaporator 15 through the ventilation duct 17, absorbs heat, and is blown into the heating chamber 4 again. During the heating operation, the circulation port 33 is closed, and the air taken in through the main body intake port 23 is drawn into the intake part of the ventilation fan 19,
As a result, fresh air is sent into the heating chamber 4 to ventilate the inside of the heating chamber 4, and then is discharged from the discharge port 26 to the outside of the main body. During this period, the progress of heating, such as the set high frequency output and the remaining heating time, is reported to the user by the fluorescent display tube 13.

As an example, the case of thawing frozen foods of 5 kg and 10 kg will be described below.

In the conventional thawing method in which the thawing time is divided into three stages, in the case of 5 kg, the first stage is 10 minutes and the second stage is 40 minutes.
Min, 90 minutes in the third stage, a total of 140 minutes, the finishing temperature of the food material was −2 ° C. in the central part, and the maximum surface temperature was + 5 ° C.
Also, if you thaw 10 kg, 20 minutes in the first stage,
A total of 35 minutes, 100 minutes in the second stage and 230 minutes in the third stage
It takes 0 minutes, and the finishing temperature of the food is -2.8 ℃ at the center.
The maximum surface temperature was + 8 ° C. According to this embodiment, 5
In case of kg, 10 minutes for the first stage, 35 minutes for the second stage, 3rd stage
60 minutes in total, 100 minutes in total, finishing temperature of foodstuff is -2 ° C at the center, maximum surface temperature is -1 ° C (heating chamber temperature setting-
1 ℃), and if 10kg is thawed,
20 minutes for stage, 80 minutes for stage 2, 150 for stage 3
Minutes, a total of 250 minutes, the finishing temperature of the ingredients is at the center-
It was possible to shorten the thawing time after significantly improving the finished state of 2 ° C. and the maximum surface temperature of -1 ° C. (heating chamber temperature setting -1 ° C.).

In particular, as for the high-frequency output applied during the time for promoting the second and third stages of defrosting and adjusting the thawed state to be uniform over the entire cooked product 5, only a low output of 300 W or less can be applied conventionally. In the present embodiment, when non-oscillation occurs in the intermittent high frequency, by cooling the surface part, the melting of ice is prevented in advance, and the concentration of the high frequency on the melting part due to the increase of the dielectric loss due to the melting of ice against the high frequency As a result, a larger output can be applied, and at the same time, since the temperature difference between the central portion and the surface is small, it takes less time to prepare the defrosted state uniformly in the entire cooked product 5, and the time can be greatly reduced. It was planned.

In this embodiment, the decompression operation is performed in three steps.
Although the high frequency output, the application time, and the heating chamber temperature are set appropriately for each step, as another embodiment, the number of divisions is divided into two steps as needed by the program of the microcomputer 40, and Easy operation, 4
It is also possible to divide into more than two stages to obtain a good finished state in a shorter time.

[0038]

As is apparent from the above description, according to the present invention, the heat absorbing means for cooling the heating chamber is provided inside the ventilation duct for feeding air into the heating chamber, and the operating time of the apparatus is set in multiple stages. Since the temperature of the cooking chamber is controlled by dividing the temperature into the heating chamber by the high-frequency output, the oscillation time and the operation of the heat absorbing means at each stage, the thawing can be performed in a time proportional to the increase in the weight of the food.

Further, according to the present invention, the following effects can be obtained together. First, because the thawing time has been shortened, especially due to cell destruction in the cooked food during thawing,
The amount of drip generated, which is a factor of deterioration of taste and finish, could be significantly reduced. This is because the temperature zone of -5 ° C to -2 ° C, which is said to be the maximum ice crystal production zone that causes cell destruction in the cooked food, can be passed in a shorter time. Further, by cooling the heating chamber and keeping the temperature below the refrigerator temperature of 7 ° C. or lower, it becomes possible to prevent the food from spoiling. Generally, when foodstuffs are left to stand at room temperature, for example, after 5 hours, the increase of bacteria in the foodstuffs during that time is sometimes 10%.
It is more than 00 times. However, the growth of spoilage bacteria decreases with decreasing temperature, and most of the bacteria stop their activity below freezing.

Further, by keeping the temperature in the heating chamber constant, it is not necessary to adjust the heating time according to the season of use, no special management is required, and the same thawing pattern can be set at any time at any time. It was good and could be a very easy-to-use device.

Further, since the temperature in the heating chamber can be set for each stage in the pattern of the defrosting operation, the optimum high-frequency output for each stage can be obtained according to the type of food and the initial conditions. You will be able to set the time,
Now you can get a higher quality finish.

After the thawing is completed, the temperature inside the heating chamber is maintained at the preset temperature of the third stage until the user opens the door to take out the cooked food from the heating chamber. There is no restriction on the usage time of the product, and for example, if the defrosting work is started at the end of the night and the cooked product is used on the next day, the device can be obtained in a desired finished state at any time.

Further, by providing an evaporator for cooling the heating chamber in the ventilation duct and controlling the opening / closing of the electromagnetic shutter in accordance with the heating mode, it can be used as a defrosting device or a high frequency heating device. , If necessary, the heating operation from thawing the food to the completion of cooking can be performed without changing the device while keeping the food in the heating chamber.
In the limited kitchen space, there is no need to install two types of equipment, a defrosting equipment and a heating equipment, and we were able to save space in the place of use.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a high frequency heating apparatus of the present invention.

FIG. 2 is a control circuit diagram of the same.

FIG. 3 is a diagram showing each output control pattern of the control device.

FIG. 4 is a sectional view showing an example of a conventional high-frequency heating device.

FIG. 5 is a diagram showing a defrosting operation of a conventional high-frequency heating device.

[Explanation of symbols]

 1 High-frequency oscillator 4 Heating chamber 15 Evaporator (heat absorbing means) 17 Ventilation duct 18 Blow-in port

Claims (3)

[Claims] 1. A heating chamber in a main body, a high-frequency oscillator for irradiating the heating chamber with a high frequency, and a blower opening provided in a wall surface portion forming the heating chamber, and a ventilation duct for feeding air into the heating chamber through the blow-in opening. It is provided with a heat absorbing means for air by evaporating a refrigerant for cooling the heating chamber inside the ventilation duct, and further divides the operation time of the device into multiple stages, and the high frequency output and oscillation time at each stage and A high-frequency heating device configured to control the temperature in the heating chamber by the operation of the heat absorbing means. 2. The high-frequency heating device according to claim 1, wherein the temperature of the heating chamber is controlled by the operation of the air heat-absorbing means, which is held for a period until the door is opened after thawing. 3. An exhaust port provided on a wall surface of the heating chamber, a first shutter for opening and closing the exhaust port by energizing, and a second intake port of a ventilation fan for sending air into the heating chamber through a ventilation duct. And a means for selectively supplying air taken in through a circulation port or a main body intake port provided on the wall surface of the heating chamber, and a control means for arbitrarily selecting the thawing operation and the heating operation. The high-frequency heating device according to claim 1, wherein the high-frequency heating device is provided with.