JPH07253216A - High-frequency heating method and high-frequency heating device - Google Patents

Abstract

PURPOSE:To permit uniform heating like those by steam oven or heating in a water bath by a method wherein high-frequency application condition is specified depending on before arriving or after arriving at the predetermined value of temperature of either a preset maximum temperature part or a preset minimum temperature part of a matter to be heated. CONSTITUTION:The desired temperature of finishing of heating of a matter to be heated, which is received in a heating chamber 11, is specified as a temperature theta1 and a predetermined temperature, lower than the desired temperature is specified as a temperature theta2. In this case, high-frequency radio wave is projected so that a difference between a temperature H and another temperature L becomes within a predetermined theta3 until either one of the temperature H of a position preset as the maximum temperature part of temperature rise or the temperature L of a position set as the minimum temperature part of the temperature rise arrives at the temperature theta2 or the high-frequency radio wave projection is stopped and the high-frequency heating is continued. After either one of the temperature H or the temperature L has arrived at the temperature theta2, the high-frequency application is continued intermittently so that the temperature H will never exceed the temperature theta1 and will never become lower than the temperature theta2 while the high-frequency heating is finished after the temperature L has arrived at the temperature theta2 under the process of heating.

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 method and a high frequency heating apparatus for vacuum cooking by high frequency heating.

[0002]

2. Description of the Related Art In recent years, attention has been paid to the goodness of vacuum cooking, but there are various problems in vacuum cooking by high frequency heating.

Hereinafter, conventional vacuum cooking will be described.
The vacuum cooking is cooking in which vacuum-packed food is heated at a constant temperature of about 55 ° C. to 95 ° C. in a hot water bath or a steam oven, and has the following advantages. (A) Since it is a vacuum, it has good heat conduction and can be uniformly heated to a specific temperature at which it can be eaten most deliciously. (B) Since it is a vacuum, it has good penetration of seasonings and can be seasoned with a small amount of sugar or salt, which is favorable for health. (C) Since it is vacuum packed, the flavor is not impaired. (D) Since it is heated at a low temperature, the streaks and fibers are not hard but soft. (E) The yield is very high because it is cooked at a temperature that does not cause water division of protein. (F) It can be refrigerated for about one week, which is convenient for large-scale supply such as hotel banquets.

However, in a vacuum cooking operation using hot water, not only the humidity in the kitchen becomes high like in a bathroom, but there is also the risk of burns, and the fuel consumption for maintaining the hot water temperature is large. The same applies to vacuum cooking work using a steam oven. Although attempts have been made to use a high-frequency heating device such as a microwave oven as a solution to this problem, it is far from achieving a finishing temperature range of about 1 ° C. required for vacuum cooking, and conventional high-frequency heating means finishes food products. In reality, the temperature range is as high as 20 ° C.

The conventional high-frequency heating means aiming at uniform heating will be described below. They can be roughly classified into four. The first is a means to make the radio wave distribution uniform,
Various means such as stirrer blades and turntables have been devised. The second is a means to shield the radio waves with aluminum foil etc. to prevent the radio waves from concentrating on a part of the food,
Means for thawing frozen food in cold air (US Pat. No.
3536129) and the like for cooling the high temperature portion and the overheated portion to make them uniform. The third method is generally called weight-defrost or weight-cook and is widely used. It is heated by electric power and irradiation time of radio waves based on the weight of food. After that, the optimal standing time (standi
(US Pat. No. 4) means to keep the temperature uniform by heat conduction inside the food by leaving it without radio wave irradiation for (ng-time)
453066) is an example.

[0006] Fourth, means for detecting the temperature of the food and controlling the radio wave irradiation, means for using a multi-range thermistor (US Pat. No. 2657580), and the temperature sensor to keep the food below a predetermined temperature. Means of keeping (U.S. Pat. No.
3634652), means for detecting the temperature of a plurality of parts of food, reducing the radio wave output when one of the parts reaches the set temperature, and ending the heating when the other part reaches the set temperature (Japanese Patent Laid-Open No. Sho-06-62). 52-17237) and the like. In addition, as a means combining the above-mentioned third means and fourth means, for example, when thawing a frozen food, the radio wave irradiation is stopped when the surface temperature reaches 5 ° C, and when the surface temperature drops to 0 ° C. Means for estimating the internal temperature from the food surface temperature by detecting the differential value of the time change from 5 ° C to 0 ° C by re-irradiating the radio wave with the electromagnetic wave (JP-A-54-764).
No. 1) has been proposed.

An example of the conventional high-frequency heat treatment will be described below with reference to the drawings. FIG. 15 is a flow chart showing the operation of a conventional high frequency heating process. In this case, the optical fiber temperature sensor is pushed into the hottest part of the food to be heated, and this temperature is set to the temperature H. Further, another optical fiber temperature sensor is pushed into the lowest temperature portion, and this temperature is set to the temperature L. The highest temperature portion and the lowest temperature portion can be known by heating foods of the same shape in advance and checking the temperature of each portion. Also, the desired finish temperature LT1 of the food to be heated, and 1 from LT1
The temperature LT2 lower by ℃ to several ℃ is input and stored in advance in the control means such as a personal computer.

In FIG. 15, when the start key is pressed, the relays necessary for the heating operation are turned on in step 1.
The heating preparation state is set as N, and the process proceeds to step 2. In step 2, it is checked whether or not both the temperature H and the temperature L are lower than the temperature LT2, and as long as both the temperature H and the temperature L are lower than the temperature LT2, the process proceeds to step 3 and the triac of the high frequency irradiation source is turned on and heated. , Return to step 2. Therefore, the temperature H and the temperature L are equal to the temperature L.
When the operation is started from a state lower than T2, step 2-
It is heated by the loop 3 and this operation is repeated until either the temperature H or the temperature L reaches the temperature LT2.
In this case, it may be considered that the temperature H reaches the temperature LT2.

When the temperature H reaches the temperature LT2, the process proceeds to step 4. At step 4, the triac is turned on.
By setting the flag D when selecting -OFF to D = 1, the heating is prioritized at the time of shifting to step 4. Next, in step 5, it is checked whether the temperature H or the temperature L is lower than the temperature LT2. When both the temperature H and the temperature L are equal to or higher than the temperature LT2, it is determined that the heating process is completed, the process proceeds to step 13, the triac is turned off, and then the relays are turned off in step 14, and all the operations are completed. To do. However, if not, the process moves to step 6. In step 6, it is checked whether both the temperature H and the temperature L are below the temperature LT1 and it is determined whether the temperature is overheated.

If neither the temperature H nor the temperature L is equal to or lower than the temperature LT1 in step 6, the process moves to step 10 to set the flag D to D = 0, and the flag D in step 11 is set.
When the flag judgment of = 0, the triac is turned off in step 12 to stop the heating, and the process returns to step 5. However, if both the temperature H and the temperature L are equal to or lower than the temperature LT1, the process proceeds to step 7 and the temperature H or the temperature L Either is temperature L
Check if it is lower than T2. If either the temperature H or the temperature L is lower than the temperature LT2 in step 7, the flag D is set to D = 1 in step 8, the process proceeds to step 9 and the triac is turned on to continue heating, and the process returns to step 5. However, if either the temperature H or the temperature L is equal to or higher than the temperature LT2, the process proceeds to step 11, the value of the flag D at that time is determined, and the heating in step 9 is performed.
Alternatively, after the heating is stopped in step 12, step 5 is performed.
Return to.

At the time of shifting to step 4, the temperature H has reached the temperature LT2, but the temperature L has not yet reached the temperature LT2, and since D = 1 has been set in step 4, step 5- The heating operation is repeated in a loop of 6-7-11-9-5. In the process of this operation, temperature H and temperature L
When both reach a state where the temperature is not lower than the temperature LT1 (a state where either the temperature H or the temperature L exceeds the temperature LT1), the routine proceeds to step 10 and the flag D is set to D = 0. Therefore, the operation of stopping heating is repeated in the loop of step 5-6-10-11-12-5, and the higher temperature of the temperature H and the temperature L gradually decreases, and
Due to heat conduction, the internal temperature difference gradually decreases. When either the temperature H or the temperature L becomes lower than the temperature LT2 in the course of this operation, the heating operation is repeated in the state of the flag D = 1 by the loop of steps 5-6-7-8-9-5.

As described above, the operation based on the determination of the flag D is continued, and the temperature H becomes L by repeating the heating and the heating while the upper limit of the temperature is set to the desired finish temperature LT1.
As the temperature rises to T1, the temperature L also rises above the temperature LT2. At this point, step 5 determines that the heating process has ended, so the heating process ends through the route of steps 13-14.

[0013]

With such a conventional high-frequency heating means, it is difficult to keep the difference between the temperature of each part of the food at the end of heating and the desired finish temperature within several degrees centigrade. For example, FIG. 16A shows the result when the heat treatment according to the flowchart shown in FIG. 15 is performed.
Even if the fiber optic thermometer is pushed into food, there is no phenomenon that only that part is overheated.
Even if T1 = 65 ° C. is set, the temperature H exceeds 65 ° C., and the temperature L hardly rises.

Further, even if various conventional means are combined, the temperature of each part of the food is accurately measured, and computer control such as predictive control is used, for example, even if heating is attempted to finish at 65 ° C., only a part of the temperature is 65 ° C. , And the other parts remain cold without being heated. In addition, the defrosting means that gradually reduces the high-frequency heating irradiation power with the passage of time has a relatively good result in the defrosting process, probably because the latent heat of 80 calories at 0 ° C serves as a buffer. However, due to various variations,
There is a large difference between the desired finish temperature and the temperature of each part of the food. In addition, it is said that flat foods such as tongue flats have even more severe non-uniformity and are completely unsuitable for high frequency heating. In addition, there are many examples in which even if specific food can be uniformly heated with a specific device, non-uniform heating can be performed with respect to any other food.

The present invention solves the above problems, and provides a high-frequency heating method and a high-frequency heating device capable of heating the temperature of each part of food to within several degrees at most with respect to the desired finish temperature in vacuum cooking. The purpose is to

[0016]

According to the present invention according to claim 1, in a high frequency heating process for heating an object to be heated housed in a heating chamber by irradiating it with a high frequency radio wave, a desired finish temperature is θ1, and the desired temperature is from θ1. The predetermined low temperature is θ2,
The temperature H at the position specified in advance as the highest part of the temperature rise and the temperature L at the position specified as the lowest part are always detected, and unless either the temperature H or the temperature L reaches the temperature θ2, the temperature H When the temperature difference from the temperature L is within a predetermined value θ3, high frequency radio waves are emitted, and when the temperature difference becomes θ3 or more, the process of stopping the irradiation is repeated until either the temperature H or the temperature L is reached. As long as either the temperature H or the temperature L does not reach the temperature θ1 after the temperature becomes equal to or higher than the temperature θ2, if either the temperature H or the temperature L becomes lower than the temperature θ2, the high frequency radio wave is radiated, If either H or temperature L is higher than the temperature θ2, the operation of stopping the irradiation of the high frequency radio wave is repeated, and the process is terminated when both the temperature H and the temperature L become the temperature θ2 or higher. Frequency heating method,
The present invention according to claim 2 is a high-frequency heating process in which a heating target housed in a heating chamber is irradiated with a high-frequency radio wave for heating, and the temperature θ of the heating target is changed from an initial temperature θ 0 by high-frequency heating for a heating time τ. The temperature rise characteristics that change to the desired finish temperature θn are specified by Newton's cooling formula, and the integrated high-frequency irradiation power W (τ) that is irradiated during the heating time τ is set in accordance with the object to be heated, and heating is performed. The temperature rise function Δ (t) obtained from the temperature rise characteristic is obtained from the change characteristic of the integrated high frequency irradiation power W (t) from the start to the time t.
= (Θ (t) -θ0), the high frequency irradiation power amount per unit time is used as the change rate of the integrated high frequency irradiation power amount W (t), and irradiation is performed with the high frequency irradiation power amount per unit time. The present invention according to claim 6 is a high-frequency heating method in which the integrated high-frequency irradiation power amount W (τ) is irradiated in a time-divided manner by a temperature increasing function Δ (t) by sequentially performing the operations. In a high-frequency heating process in which a heating target housed in a heating chamber is irradiated with high-frequency radio waves for heating, the temperature θ of the heating target varies from an initial temperature θ0 to a temperature θi (i = 1, 2, , ..., n-1), the temperature rise characteristics that change to the desired finish temperature θn are defined by the Newton cooling formula, and the integrated high-frequency irradiation power W (τ) for irradiation during the heating time τ Set according to the object to be heated The change characteristics of the integrated from the start of heating until time t microwave irradiation power amount W (t), the temperature rise function obtained from the temperature rise characteristic Δ (t) = (θ (t) -θ
0), the high frequency irradiation electric energy per unit time in the temperature section from temperature θi to θi + 1 is taken as the change rate of the integrated high frequency irradiation electric energy W (t) defined in this section, and The temperature of the object is θ j (j = 0, 1, 2, ...,
n-1) is a high-frequency heating method in which the operation of irradiating with the high-frequency irradiation power amount per unit time is sequentially executed for each temperature section from the time when it reaches n-1) to the temperature reaches θj + 1. The present invention according to claim 19 relates to a heating chamber for accommodating an object to be heated, a high-frequency heating source for irradiating the object to be heated with high-frequency radio waves, and a controller for controlling a high-frequency irradiation operation of the high-frequency heating source. And a control unit for controlling the heating process according to any one of claims 1 to 18.

[0017]

In the present invention according to claim 1, the high frequency radio wave is applied while the temperature difference between the temperature H in the vicinity of the highest temperature portion and the temperature L in the vicinity of the lowest temperature portion does not exceed the predetermined value .theta.3. The superheat is uniformly heated while being diffused by heat conduction inside the object to be heated.

In the present invention according to claim 2, the temperature characteristic of the object to be heated is defined by the Newton's cooling equation, and the change characteristic of the integrated high frequency irradiation electric energy is set based on the temperature rising function calculated from that, and The total integrated high frequency irradiation power is distributed by the function by time and irradiation is performed.

In the present invention according to claim 6, the change characteristic of the integrated high frequency irradiation power amount and the high frequency irradiation power amount per unit time are defined based on the temperature rising function defined in each temperature interval, and in each temperature interval. Then, high-frequency radio waves are emitted until the temperature at the end point of the section is realized according to the conditions defined in that section, and the operation moves to the next temperature section.

In a nineteenth aspect of the present invention, the control section executes each of the above heating methods.

[0021]

【Example】

(Embodiment 1) An embodiment of a high frequency heating method and a high frequency heating apparatus according to the present invention will be described below with reference to the drawings. FIG. 1A is a perspective view showing the configuration of the high frequency heating apparatus of this embodiment, and FIG.
It is an A'sectional view. In FIG. 1A, 11 is a heating chamber made of stainless steel, 12 is a food placing table made of crystal glass fixed to the bottom of the heating chamber 11, 13 is a door that closes the opening of the heating chamber 11, and 14 is a device. An operation unit provided on the front upper part of the device, and 15 is an outer box forming an outer wall of the apparatus.

Further, in FIG. 1 (b), 16 is an oil mat placed on the food placing table 12, 17 is a net of the cages placed on the oil mat 16, and 18 is an inside of the cage 17 of the cage. A multi-core shield wire for electrically connecting a temperature sensor (not shown) provided in the, a metal plug 19 connected to one end of the multi-core shield wire 18, and 20 fixed to the rear wall of the heating chamber 11. It is a metal connector. For example, RS-2 used in personal computers
A 32C plug and connector may be used. It should be noted that in the present embodiment, since the temperature measurement by the cage net 17 is not performed, it will be described in another embodiment. Reference numeral 21 is a food to be heated placed on the mesh net 17 of the cage, and 22 is an oil mat placed so as to cover the food 21 to be heated. 23 is a resin stirrer cover provided on the upper part of the heating chamber 11, and 24 and 26.
Is an antenna, 25 and 27 are rotation motors for rotating the antenna 24 and the antenna 27, respectively, and 28 is the heating chamber 11.
, 29 is a waveguide provided under the heating chamber 11, 30 is a magnetron provided at one end of the waveguide 28, and 31 is a magnetron provided at one end of the waveguide 29. ..

Reference numeral 32 is a fan motor for forcibly cooling the magnetron 30, 33 and 40 are a group of small holes provided on the back wall surface 38 of the outer box 15 for discharging hot air in the heating chamber 11 to the outside, and 35 is a fan. A group of small holes for introducing the cold air by the motor 32, a group of 36 for discharging the cold air introduced from the group of small holes 35 into the heating chamber 11, a reference numeral 37 for an exhaust guide, and a reference numeral 39 for introducing the cool air from the outside. This is a group of small holes provided on the bottom wall surface of the outer box 15 for this purpose.

FIG. 2A is a perspective view showing the structure of the oil mat 16 and the oil mat 22, and FIG.
It is a C'cross section. In the figure, 80 is a polyethylene layer having a thickness of about 50 microns, and 81 is a nylon layer having a thickness of about 20 microns, which form a rectangular bag 82. Reference numeral 83 is a edible oil such as a commercially available salad oil enclosed in a rectangular bag-like container 82, and 84 is a heat-sealed portion.

FIG. 3 is a circuit diagram showing the structure of the high frequency heating apparatus of this embodiment. In the figure, 25 and 27 are antenna rotation motors that rotate antennas that output high-frequency radio waves, 30 and 31 are magnetrons that oscillate high-frequency waves, 51 is a power plug, and 32 and 58 are fan motors for cooling magnetrons, respectively. Is a fuse, 5
3 is a noise filter coil, 54 is a lamp that illuminates the heating chamber, 55 is a relay that opens and closes the lamp 54, 56 is a magnetron heater transformer, 57 is a relay that opens and closes the heater transformer 56, and 60 and 61 are heating chambers, respectively. , 62 and 63 are main relays, 64 and 65 are short switches, 66 and 67 are triacs, 68 and 69 are high voltage transformers, 70 and 71 are trigger circuits, and 90. Is a personal computer (hereinafter referred to as a personal computer) 91 for controlling the operation of the apparatus, RS-232C cable connected to the personal computer, 92 is an optical fiber thermometer, and 93 and 94 are optical fiber temperature sensors.
The optical fiber temperature sensors 93 and 94 are pushed into the food to be heated. The fiber optic thermometer can measure temperature even in a high frequency irradiation environment, and there is little temperature disturbance in the system to be measured, that is, the phenomenon of overheating only the pressed part when it is pressed into food does not occur. Accurate temperature measurement is possible. Optical fiber temperature sensor 9
One of 3 and 94 is inserted in the vicinity of the portion where the temperature rises highest, and the temperature is set to the temperature H. Further, another is inserted near the portion where the temperature rise is the lowest, and the temperature is set as the temperature L. Also, the desired finish temperature LT1 of the food to be heated,
Enter the temperature LT2, which is 1 ° C to several ° C lower than the temperature LT1, into the personal computer and store it. These conditions are the same as those of the conventional example described in FIG.

The operation of the above configuration will be described with reference to the drawings. FIG. 4 is a flowchart showing the operation of the high frequency heat treatment in this embodiment. The processing operation of this embodiment differs from the processing operation of the conventional example shown in the flowchart of FIG. 15 in that the temperature H and the temperature L are in the first half of the processing.
There is a step 15 for checking the temperature difference between the two and a step 16 for turning off the triac according to the result. The setting of the optical fiber temperature sensor 93 and the optical fiber temperature sensor 94, the setting of the temperature H and the temperature L, the setting of the temperature LT1 and the temperature LT2 are the same as those in the conventional example, and the operation after step 4 is also the same. Is omitted.

In FIG. 4, when the start key is pressed, all relays (55, 57, 6
2 and 63) are turned on to set the heating preparation state, and the process proceeds to step 2. In step 2, it is checked whether the temperature H and the temperature L are both lower than the temperature LT2,
Unless both the temperature H and the temperature L are lower than the temperature LT2 (the same as long as either the temperature H or the temperature L is not higher than the temperature LT2), the routine proceeds to step 15. In step 15, it is checked whether or not the difference between the temperature H and the temperature L is lower than 20 ° C. If the temperature difference is smaller than 20 ° C., the process proceeds to step 3 and the trigger circuit 70 causes the triac 66 to trigger. Triac 6 by circuit 71
7 and ON to start heating and return to step 2,
Unless the temperature difference is smaller than 20 ° C. (the same as when the temperature difference becomes 20 ° C. or more), the process proceeds to step 16, the triac is turned off to stop the heating, and the process returns to step 2. Therefore, when the operation is started from the state where the temperature H and the temperature L are lower than the temperature LT2, the loop is heated in the step 2-15-3, but the temperature difference between the temperature H and the temperature L is 20.
When the temperature rises above the temperature, heating is interrupted by the loop of step 2-15-16, and the temperature difference is reduced due to heat conduction inside the object to be heated. By repeating this operation, heating is continued while making the temperature difference smaller than 20 ° C., and either the temperature H or the temperature L reaches the temperature LT2. In this case, it may be considered that the temperature H reaches the temperature LT2. When the temperature H reaches the temperature LT2, the process proceeds to step 4. The subsequent processing is the same as that of the conventional example shown in FIG.

FIG. 5 is a characteristic diagram showing the relationship between time and temperature when about 900 g of pork refrigerated at about 0 ° C. to 5 ° C. is heated to the desired temperature LT1 = 65 ° C. by the above heat treatment. is there. In this case, LT1 = 65 ° C, L
Input T2 = 64 ° C. Moreover, 500g of salad oil is sealed in a bag about 23cm wide and about 30cm long with a film about 0.1mm thick to form a plate-like oil mat about 1cm thick, sandwiched from the top and bottom of pork. It was used by being sandwiched between. The heating time was 2 hours and 30 minutes, the integrated power value measured on the primary side of the high-voltage transformer 68 and the high-voltage transformer 69 was 136 wh, and the temperature of each part of the pork was 64.
Good results were obtained between ℃ and 66 ℃. In addition, the temperature rise data when 900 g of pork was vacuum-cooked to 65 ° C. in about 2 to 2.5 hours by a steam oven is also shown in FIG. 5. Compared with this, cooking by the high frequency heat treatment of this example is shown. It is understood that is almost the same as the vacuum cooking with the steam oven.

FIG. 1 shows the result of the high frequency heating treatment of this embodiment.
Comparison is made with the result of the high frequency heating of the conventional example shown in FIG.
FIG. 16 is a characteristic diagram showing the results of the high frequency heating of the conventional example and the results of the high frequency heating of the present invention in comparison. In the conventional example, as shown in FIG. 16 (a), the temperature H greatly exceeded 65 ° C. although the temperature L hardly increased. Therefore, if the temperature LT1 is set to 40 ° C. and the high frequency irradiation is stopped when the temperature LT1 reaches about 40 ° C., the phenomenon of exceeding 65 ° C. can be prevented as shown in FIG. 16 (b). However, the temperature L does not rise. On the other hand, when the high frequency irradiation is performed only when the difference between the temperature H and the temperature L is, for example, within 20 ° C. as in the present embodiment, as shown in FIG. Uniform heating was possible so that the difference between the L and the desired temperature LT1 was within 1 ° C.

Hereinafter, the temperature difference between the temperature H and the temperature L is 20 ° C.
The reason why the high-frequency heat treatment of the present example controlled to 2 gives good results will be discussed. It can be estimated that the specific heat of pork is about 0.35 and the specific heat of salad oil is about 0.4.
The total calorie of 00g of pork and the oil mat is about 715.
Equivalent to cc of water. The amount of heat required to raise this from 5 ° C to 65 ° C is 429000 calories.
When divided by 60 and converted to electric energy, it becomes 49.8wh. On the other hand, of the integrated electric energy of 136 wh on the primary side of the high-voltage transformer 68 and the high-voltage transformer 69, the ratio of being absorbed by the object to be heated as the high-frequency irradiation electric energy is about 53% in the experimental equipment, so 72.0 wh It is considered to be the amount of high-frequency irradiation power. Therefore, 49.8 / 72.0 = 6
It can be interpreted that 9.1, that is, about 70% of the amount of electric power is absorbed by the object to be heated and the other 30% or more is lost.

In the characteristic diagram shown in FIG. 5, the integrated electric energy of 136 wh is also shown. However, since the dimensions are different, the scale is forcibly matched with 136wh = 65 ° C. According to FIG. 5, it can be seen that the change characteristic of the integrated electric energy and the change characteristic of the temperature L, which is the lowest temperature portion of the pork, are on almost the same curve. In order to confirm whether this phenomenon is universal, as another food, minced beef is packed in a meatloaf mold and vacuum packed to 100%.
A characteristic diagram of FIG. 6 shows the results obtained by sandwiching two pieces of the same oil mat as in the above-mentioned embodiment with four kinds of weights of g, 200 g, 500 g and 800 g, and heating to 58 ° C. by the processing of the flowchart shown in FIG. From this result, it can be said that the similar relationship between the integrated electric energy and the change in the lowest temperature part is a universal phenomenon.

Table 1 shows the relationship between the input electric energy (integrated electric energy) and the absorbed heat energy (electric power conversion) of the food to be heated in the high frequency heating.

[0033]

[Table 1]

In Table 1, the first row shows the total heat of meat and oil mat when the specific heat of beef is about 0.43,
The second row is the amount of heat of water having the same weight as the meat, which is assumed as the amount of absorbed heat, the third row is the integrated electric energy on the primary side of the transformer, and the fourth row is the integrated high-frequency wave irradiated into the heating chamber 11. The amount of irradiation power. In order to convert the integrated power amount into the integrated high frequency irradiation power amount, the water load amount characteristic of the conversion efficiency between the integrated power amount and the integrated high frequency irradiation power amount shown in FIG. 7 is used. Although the description of the absorbed heat amount is omitted, there is a similar tendency when the oil mat is not used. The fifth line is the value of (heat quantity of water equivalent to meat) / (integrated high frequency irradiation power quantity), which falls within the range of 66% to 88%. That is, the integrated electric energy is about 25 on average.
It may be assumed that it is absorbed by the equivalent amount of water of meat with% loss.

In summary of the above consideration, the amount of heat required to finish the same amount of water as the food to be heated and raise it to the desired temperature is 25
Similar to a steam oven by adding high frequency irradiation power with a heat amount of about% and irradiating the time required for vacuum cooking in the steam oven with time distribution along the temperature rise curve of the central part It is thought that the uniform heating of is possible. Particularly, in the present embodiment, the means for repeating high frequency irradiation and irradiation stop so that the internal temperature difference becomes smaller than 20 ° C., the irradiation is stopped and heat conduction occurs when the food to be heated is partially overheated. This contributes to the realization of high-frequency heating that is equivalent to the heat conduction-based heating that follows Newton's cooling law, such as cooking in a steam oven. It is a means of allocating time according to the pattern.

As described above, according to this embodiment, the magnitude of the temperature difference between the highest temperature portion and the lowest temperature portion of the object to be heated is set to a predetermined value or less, and the temperature of the highest temperature portion is set to the finishing temperature or less, By heating by repeatedly irradiating and stopping high-frequency radio waves so that the temperature is higher than a predetermined temperature, it is possible to heat in a pattern equivalent to the temperature rise characteristics near the center in cooking with a steam oven or boiling water, and achieve uniform heating. be able to.

(Embodiment 2) An embodiment of the high frequency heating method and the high frequency heating apparatus of the present invention according to claim 2 will be described below. In Example 1, by applying high-frequency irradiation while controlling the internal temperature difference using the optical fiber temperature sensor, it was possible to heat in a pattern equivalent to the temperature rise characteristics near the central portion cooked in a steam oven or hot water bath. The degree of vacuum is lowered because the resin bag of the vacuum pack is penetrated to insert the sensor into food. In addition, it is very difficult to pierce the packing with sponge-like adhesive used for that purpose with a weak optical fiber temperature sensor.

This embodiment provides means for not using the optical fiber temperature sensor to solve the above problems. As described in Example 1, when uniform high-frequency heating equivalent to cooking with a steam oven or hot water is achieved, the time distribution of the cumulative high-frequency irradiation power is the characteristic of the temperature rise value when cooking with a steam oven or hot water. It was the same as the curve. Based on the above consideration results, the present Example, the integrated high-frequency irradiation power required to raise the heated food to a predetermined temperature, the same as the characteristic curve of the temperature rise value when cooked by a steam oven or hot water It is a means to realize uniform heating by allocating time to the above, and does not require an optical fiber temperature sensor.

In this case, if the temperature rise characteristic can be made into a time function, it is convenient for the calculation of time distribution. The following Newton's law of cooling can be applied when the temperature rise characteristic of cooking by the steam oven or hot water is made into a function.

(Θw−θ) / (θw−θ0) = exp (−kt) where, θw: hot water temperature of hot water or steam oven temperature θ: internal temperature of food to be heated θ0: food to be heated Initial temperature k: Proportional constant (values differ between boiling water and steam oven) t: Elapsed time. The above equation gives the property that when the food to be heated whose initial temperature is θ0 is left in the atmosphere of temperature θw, when θw <θ0, the food to be heated is cooled toward the temperature θw. Is called the law of θw> θ0
When it is, it gives a characteristic of being heated toward the temperature θw. Also, when θw = θ0, there is no temperature change, so it corresponds to the storage state. FIG. 8 shows the measured value of the internal temperature rise value when vacuum cooking 900 g of pork in a steam oven and the calculated value (θ−θ0) of the temperature rise value when an appropriate value of k is substituted into the above formula. It is a characteristic diagram compared. There is a slight difference in the initial heating, but they are almost the same,
It was confirmed that the Newton's cooling system was applicable. Therefore, if the amount of heat (integrated high-frequency irradiation power) is time-allocated along the function of the temperature rise value derived from the Newton's cooling formula and added, it is possible to use a steam oven or boiling water even without using an optical fiber thermometer. It is thought that heating can be realized.

The present embodiment will be described below with reference to the drawings. FIG. 9 is a flow chart showing the operation of the heat treatment of this embodiment. Note that this heat treatment can be carried out by a high frequency heating device except the optical fiber thermometer from the configuration shown in FIG.

The program is started, and in step 1, the weight of the food to be heated (hereinafter referred to as w), and in step 2, the desired finished temperature rise value θ (desired food finish temperature θn
(A value obtained by subtracting the initial temperature θ0 from the above), and the heating time τ spent for the temperature rise value θ is input to the personal computer 90 in step 3. Next, in step 4, the necessary cumulative high-frequency irradiation power amount to be applied to the heating chamber is temporally distributed to calculate the number of times of irradiation n0. It is ideal that the integrated high-frequency irradiation power is continuously time-distributed according to the Newton's cooling law, but the apparatus becomes complicated. Therefore, the time is distributed stepwise by a combination of short-time irradiation and irradiation stop, and the number of repetitions is set to n0. First, based on the above consideration, the integrated high-frequency irradiation power is calculated by multiplying the food weight w by the desired temperature rise θ, multiplying it by 1.25 in consideration of the 25% loss mentioned above, and dividing by 860. Ask for. Next, the electric energy is divided by the nominal high-frequency output value (rated output value) to calculate the cumulative irradiation time, which is multiplied by 3600 and converted to the unit of seconds. Further, the irradiation time is set to 3 seconds according to the experimental result, and the high frequency irradiation power amount during that period is set to be constant.
Therefore, the number of irradiations n0 is calculated by dividing by 3. The remainder will be discarded. The irradiation time of 3 seconds is a value according to the capability of the irradiation device, and it is important that the irradiation time is too long and partial overheating does not occur. It is a value that should be determined in consideration of the fact that the partial heat generation is made uniform by the heat diffusion inside the food.

Next, in step 5, since n0 times are assigned to the heating time τ according to the Newton's formula, if the time required to reach a temperature 1 ° C. lower than the desired temperature is substituted as τ, the first time t1 = log (1-1 / n0) / (1 / τ · log (1 / θ)) nth time tn = log (1-1 / n0) / (1 / τ · log (1 / θ)) The time is calculated up to (n0 -1) times and stored. In this case as well, the remainder is discarded.

Next, the process proceeds to step 6, where the operator places the food to be heated in the heating chamber and waits for the start key to be pressed. When the start key is pressed, the process proceeds to step 7 and the relays 55, 57, 62 and 63 are turned on, and the process proceeds to step 8 where undefined t0 is set to 0 and the frequency counter is set to n = 0. Next, in step 9, the time elapsed since the start key is pressed is constantly checked, and when the count value n of the number counter reaches the designated tn time, the process proceeds to step 10. Step 10
In, the triac is turned on, the process proceeds to step 11 and waits until the elapsed time reaches (tn + 3), then the process proceeds to step 12 and the triac is turned off. Heating is performed for 3 seconds in steps 10-11-12.

Next, in step 13, the count value n of the number counter is incremented by 1 to (n + 1), and in step 14, it is checked whether the n value is less than (n0-1). To do. If it is less than the above, it is determined that the processing has not been completed, the process returns to step 9, and the same operation is repeated.
If it is (n0-1), it is determined that the processing is completed, and the routine proceeds to step 15, where the relays 55, 57, 62 and 63 are turned off and the processing is ended.

As described above, according to the present embodiment, the temperature rising characteristic of the food to be heated in the cooking by the steam oven or hot water is set, and the integrated high frequency irradiation electric energy is time-divided and irradiated in the same pattern. This makes it possible to achieve uniform heating equivalent to cooking with a steam oven or hot water, without using a temperature sensor.

In this embodiment, the conversion efficiency between the input power and the high-frequency irradiation power is assumed to be 25%, but it depends on the material and shape of the food, the weight and shape of the oil mat, the contact condition between the food and the mat, etc. It is not limited to 25%. Further, although the high frequency irradiation time is set to 3 seconds, it goes without saying that it may be set to a time that does not cause overheating due to the irradiation capacity of the apparatus.

Although the case where the time is distributed in conformity with the function of the temperature rise has been described, the function may be approximated by a polygonal line or a combination of a polygonal line and a curve. In addition, when approximated, the heating time is distributed more in the first half and less in the latter half,
The heating time may be shortened by allocating so as to match at the end point.

(Embodiment 3) An embodiment of the high-frequency heating method and the high-frequency heating apparatus of the present invention according to claim 6 will be described below. In Example 2, the conversion efficiency with respect to the input power was assumed to be 25% in order to determine the integrated high frequency power, but as described above, the value of the conversion efficiency depends on the material and shape of the food, the weight and shape of the oil mat, It depends on the contact condition between the food and the mat, etc., and many trials are required before it is possible to determine the integrated high-frequency power amount that achieves favorable results in terms of finishing temperature and uniformity.

The present embodiment is a means for solving the above problems, and is a means for controlling the amount of high frequency irradiation power while monitoring the rise value of the surface temperature of the object to be heated. This embodiment is the first embodiment.
What is different from the above is that the surface temperature is measured instead of the internal temperature of the object to be heated, and the high frequency irradiation electric power per unit time is given in the pattern of temperature rise based on the Newton's cooling formula. The difference from 2 is that the temperature rise value is checked during heating.

The point of the present embodiment is to set the Newton's cooling formula for the temperature change of the object to be heated. This is approximated by a polygonal line, and the high frequency heating amount per unit time corresponding to each linear formula is set. When heating and reaching the intersection temperature of the polygonal line, the operation shifts to heating with high frequency irradiation electric energy per unit time corresponding to the following linear equation. After performing this operation for each broken line, heating is terminated. In this case, the amount of high-frequency irradiation power per unit time is determined by the periodic operation of high-frequency irradiation for a predetermined time and the irradiation stop as in the second embodiment, but the irradiation stop time in one straight line section is naturally a constant value. Is. However, the number of times of irradiation is not defined as in Example 2, and the irradiation is repeated until the measured surface temperature reaches the intersection temperature of the polygonal lines. By this temperature control, the heating accuracy is improved as compared with the means of the second embodiment in which the integrated high frequency irradiation power amount and its time distribution are defined in advance. Also,
In the present embodiment, the internal temperature of the object to be heated is not measured, but since it is high frequency heating based on Newton's cooling formula, partial overheating is suppressed and uniform heating is performed, and the surface temperature is measured instead of the internal temperature. That's enough.

The present embodiment will be described below with reference to the drawings. First, prior to the description of the heating method, the surface temperature measuring means used in this example will be described. Figure 1
0 (a) is a perspective view showing the configuration of the cage net 17 used in this embodiment, and FIG. 10 (b) is a BB 'sectional view thereof.
In the figure, 41 is a frame-shaped frame made of a metal round bar,
42 is a hollow circular metal rod-shaped body inserted and fixed in holes provided on the front side and the rear side of the frame 41, 43 is a thermistor provided inside the hollow of the rod-shaped body 42, and 44 and 45 are The pair of mounting brackets are fixed by fixing screws 46 with the rear side of the frame 41 sandwiched therebetween. In addition, 18 is a multi-core shielded wire for connecting the thermistor 43, and 19 is a metal plug.
The rod-shaped body 42 is, for example, a metal tube having an inner diameter of 1.3 mm and a wall thickness of about 0.18 mm, which is manufactured by the same manufacturing method as that of the injection needle, and is fixed to the frame 41 and then plated with nickel. The thermistor 43 is inserted into the hollow inside of the rod-shaped body 42, and its two lead wires are insulated at least in the area located inside the rod-shaped body 42, and the triangular space formed by the frame 41 and the mounting brackets 44 and 45. Inside, it is electrically connected to one of the core wires of the multi-core shield wire 18. In addition, a concave portion is provided at the center of the mounting brackets 44 and 45, and at this portion, it is electrically connected to the metal sheath of the multi-core shielded wire 18. The thermistor 43 and its lead wires are electrostatically shielded by the rod-shaped body 42, the fittings 44 and 45, the metal jacket of the shield wire and the metal plug 19. In the present embodiment, seven thermistors 43 are used, and among the 17 rod-shaped bodies 42 shown in FIG.

FIG. 11 is a circuit diagram showing the structure of the high frequency heating apparatus of this embodiment. The same components as those in the embodiment shown in FIG. 3 are assigned the same reference numerals and detailed explanations thereof will be omitted. Further, FIG. 12 is a circuit diagram showing a configuration of the control circuit 72. In FIG. 12, 73 is a power transformer, 74 is a microprocessor for controlling the operation of the control circuit 72, and 75 is
Is a transistor for shaping the AC waveform on the secondary side of the power transformer 3 and outputting it to the port P8 of the microprocessor 74; 76 is the load resistance of the thermistor 43; and P1 to P7.
Is an input terminal with an A / D conversion function of the microprocessor 74, P9 to P14 are output terminals of the microprocessor 74, and the relays 55, 57, 62, 63 shown in FIG. It is connected to the triac trigger circuits 70 and 71. The microprocessor 74 inputs the output voltage of the temperature sensor 43 provided in the cage net 17 to detect the surface temperature of the object to be heated, and controls the operations of the magnetrons 30 and 31 by the trigger circuits 70 and 71.

The heating method of this embodiment will be described below. In this embodiment, the temperature change characteristic is shown in FIG.
It is approximated by three straight lines with reference to the characteristic diagram shown in FIG.
Now, heating time = τ, temperature rise value T1 = (θn to heat the food to be heated from the initial temperature θ0 to a predetermined finishing temperature θn
-Θ0), the temperature change curve on the characteristic diagram has points (τ / 10, T1 / 3) and (3τ / 10,
2T1 / 3) point, so the temperature change curve is approximated by three straight lines that intersect these two points. Further, in each straight line, the high frequency irradiation time is set to 3 seconds and the irradiation stop time is set to A, B, and C seconds, respectively, and is determined in the following processing steps.

The operation of this embodiment will be described below.
13 and 14 are flowcharts showing the operation of this embodiment. In FIG. 13, the steps up to step 4 for obtaining the irradiation number n0 are the same as those in the flowchart shown in FIG. Further, the purpose of obtaining the irradiation number n0 is to determine the high frequency irradiation power amount per unit time in accordance with the inclination of the approximate straight line as a standard temperature change characteristic, and to determine the irradiation number at the time of execution. Note that it is not for regulation. Next, step a
The irradiation stop time A is calculated in. The irradiation stop time A is determined by dividing (τ / 10) by (n0 / 3), discarding the remainder, and then subtracting 3 seconds. Next, in step b, the irradiation stop time B is similarly determined. Divide (3τ / 10) by (n0 / 3), discard the remainder, and subtract 3 seconds to determine. Next, in step c, the irradiation stop time C
To decide. The irradiation stop time C is determined by dividing (τ-3τ / 10) by (n0 / 3), discarding the remainder, and then subtracting 3 seconds. Next, the process proceeds to step d in the flowchart shown in FIG.

In step d, each relay for starting operation is turned on, and in step e, high frequency irradiation is performed in step f while confirming that the temperature rise value detected by the food surface temperature detecting means does not reach T3 = T1 / 10. 3
The cyclic operation of turning on for seconds and turning off for A seconds is repeated. When the temperature rise value reaches T3 in step e, the process proceeds to step g, and the temperature rise value is T2 = 3T1 / 1 /
While confirming that 0 is not reached, in step h, the periodic operation of turning on the high frequency irradiation for 3 seconds and turning off for B seconds is repeated. In step g, the temperature rise value is T
When it reaches 2, the process proceeds to step i and the temperature rise value is T
While confirming that 1 is not reached, in step j, the periodic operation of turning on the high frequency irradiation for 3 seconds and turning it off for C seconds is repeated. When the temperature rise value reaches T1, the process goes to step k to turn off all the relays and finish the heating process. As a result of the above heat treatment, the result that the difference from the desired finish temperature was within 1 ° C. was obtained as in Example 1.

As described above, according to this embodiment, the function of the temperature rise characteristic of the food to be heated is approximated by three straight lines,
Determine the high frequency irradiation power per unit time corresponding to the function of each straight line, radiate high frequency while measuring the surface temperature of the food to be heated, when the temperature at the intersection of the polygonal lines is reached, the unit corresponding to the next straight line By performing the operation of irradiating with the high-frequency irradiation power per time for each straight line, the high-frequency heat treatment is performed to bring the surface temperature of the processing process to a predetermined value. Irradiation amount error is compensated for, and it is possible to achieve a finish temperature and uniform heating that are equivalent to heating with a steam oven or boiling water.

Although the heating by the linear approximation of three lines has been described in the embodiment, it is needless to say that the processing accuracy can be improved by further increasing the number of broken lines and combining a curved line and a straight line. Further, in the present embodiment, the temperature of the object to be heated was measured by the surface temperature, but since the high frequency irradiation based on the Newton's cooling formula is performed, the temperature uniformity is realized, the temperature difference with the inside is small, and It is not always necessary to measure the temperature of.
However, it goes without saying that the internal temperature may be measured. Also, when measuring the surface temperature, it is effective to consider the temperature gradient between the cage and the internal temperature sensor, and the surface temperature is measured by inserting an optical fiber thermometer between the oil mat and the object to be heated. The same applies to the case. Further, the temperature difference between the internal temperature and the surface temperature of the object to be heated is checked, and when the temperature difference becomes large, the operation of suspending the irradiation is added to compensate the error of the linear approximation. You may Alternatively, the amount of high-frequency irradiation power per unit time in the first straight line approximation may be increased, and the second and subsequent straight lines may be irradiated with a small amount so that they match at the end point.

[0059]

As is apparent from the above embodiments, the present invention according to claim 1 can achieve a desired finish temperature in a high-frequency heating process in which an object to be heated housed in a heating chamber is irradiated with high-frequency radio waves for heating. θ1, a predetermined temperature lower than the temperature θ1 is θ2, and the temperature H at a position specified in advance as the highest part of the temperature rise and the temperature L at a position specified as the lowest part are always detected, and either the temperature H or the temperature L is detected. If the temperature difference between the temperature H and the temperature L is within a predetermined value θ3, high-frequency radio waves are emitted unless the temperature reaches the temperature θ2, and the irradiation is stopped when the temperature difference becomes θ3 or more. The above process is repeated, and when either the temperature H or the temperature L exceeds the temperature θ2, the temperature H
Alternatively, unless either the temperature L or the temperature L1 reaches the temperature θ1, high frequency radio waves are emitted when either the temperature H or the temperature L becomes lower than the temperature θ2, and either the temperature H or the temperature L is equal to or higher than the temperature θ2. In some cases, the operation of stopping the irradiation of the high frequency radio wave is repeated, and the processing is ended when both the temperature H and the temperature L become the temperature θ2 or more, and the present invention according to claim 2 In the high-frequency heating process in which the object to be heated stored in the heating chamber is irradiated with high-frequency radio waves and heated, the temperature θ of the object to be heated changes from the initial temperature θ0 to the desired finish temperature θn due to the high-frequency heating for the heating time τ. The rising characteristic is defined by the Newton's cooling formula, and the integrated high-frequency irradiation power W (τ) for irradiation during the heating time τ is set corresponding to the object to be heated, and the heating is started for t hours. The change characteristic of the integrated high-frequency irradiation power W (t) in (1) is defined based on the temperature increase function Δ (t) = (θ (t) −θ0) obtained from the temperature increase characteristic,
The high-frequency irradiation power amount per unit time is used as a rate of change of the integrated high-frequency irradiation power amount W (t), and the irradiation operation is sequentially executed by the high-frequency irradiation power amount per unit time, thereby obtaining the integrated high-frequency irradiation power amount W (t). (τ) is the temperature rise function △ (t)
By allocating time with and irradiating,
According to the present invention of claim 6, in a high-frequency heating process for heating an object to be heated housed in a heating chamber by applying a high-frequency radio wave, the temperature θ of the object to be heated is changed from an initial temperature θ 0 by high-frequency heating for a heating time τ. Temperature θi (i = 1, 2, ...
, N-1), the temperature rise characteristic that changes to the desired finish temperature θn is defined by the Newton's cooling formula, and the integrated high-frequency irradiation electric energy W (τ) irradiated during the heating time τ is defined as A temperature rise function Δ (t) obtained from the temperature rise characteristic, which is set corresponding to the heating object, and obtains the change characteristic of the integrated high frequency irradiation power amount W (t) from the start of heating to time t
= (Θ (t) -θ0) and the temperature from θi to θ
The high-frequency irradiation power per unit time in the temperature section of i + 1 is the integrated high-frequency irradiation power W defined in this section.
(t) is the rate of change, and the temperature of the object to be heated is θj (j = 0,
1, 2, ..., N-1), the temperature is θ
The irradiation with the high-frequency irradiation power amount per unit time is sequentially executed for each temperature section until reaching j + 1, and the present invention according to claim 19 relates to A heating chamber for housing, a high-frequency heating source for irradiating the object to be heated with high-frequency radio waves, and a control unit for controlling a high-frequency irradiation operation of the high-frequency heating source, the control unit controlling the heating process. By using the high frequency heating device configured as described above, uniform heating similar to cooking with a steam oven or hot water can be realized by the high frequency heating process.

In the embodiment, the vacuum cooking is described, but it is also effective for non-vacuum food.
It is also effective in thawing frozen foods. Further, it can be used not only for foods but also for heating other objects to be heated, for example, heating resin products.

[Brief description of drawings]

FIG. 1A is a perspective view showing a configuration of an embodiment of a high-frequency heating apparatus of the present invention, and FIG. 1B is a sectional view taken along the line AA ′.

FIG. 2 (a) is a perspective view showing the configuration of an oil mat used in the high-frequency heating device of the present invention (b) its BB ′ sectional view

FIG. 3 is a circuit diagram showing the configuration of an embodiment of the high-frequency heating device of the present invention.

FIG. 4 is a flowchart showing the operation of Example 1 of the high-frequency heating method of the present invention.

FIG. 5 is a characteristic diagram showing a processing result of the first embodiment.

FIG. 6 is a characteristic diagram showing another processing result of the first embodiment.

FIG. 7 is a characteristic diagram showing an example of conversion efficiency between input power and irradiation power.

FIG. 8 is a characteristic diagram showing a relationship between a temperature rise value of food based on Newton's cooling formula and an integrated high-frequency irradiation power amount.

FIG. 9 is a flowchart showing the operation of the third embodiment of the present invention.

FIG. 10 (a) is a perspective view showing the structure of a cage of the present invention. FIG.

FIG. 11 is a circuit diagram showing the configuration of an embodiment of the high-frequency heating device of the present invention.

FIG. 12 is a circuit diagram showing a configuration of the control circuit.

FIG. 13 is a partial flowchart showing the operation of the high frequency heating method according to the third embodiment of the present invention.

FIG. 14 is a partial flowchart showing the operation of the high frequency heating method according to the third embodiment of the present invention.

FIG. 15 is a flowchart showing the operation of an example of a conventional high-frequency heating method.

16A is a characteristic diagram showing an example of a treatment result of a conventional high-frequency heating method. FIG. 16B is a characteristic diagram showing another example of a treatment result of a conventional high-frequency heating method. Characteristic diagram showing the processing results of Example 1

[Explanation of symbols]

 11 Heating Room 17 Slitter Net (Surface Temperature Measuring Means) 21 Heated Food (Heating Object)

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 4, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: High frequency heating method and high frequency heating apparatus

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency heating method and a high frequency heating apparatus for vacuum cooking by high frequency heating.

[0002]

2. Description of the Related Art In recent years, attention has been paid to the goodness of vacuum cooking, but there are various problems in vacuum cooking by high frequency heating.

Hereinafter, conventional vacuum cooking will be described.
The vacuum cooking is cooking in which vacuum-packed food is heated at a constant temperature of about 55 ° C. to 95 ° C. in a hot water bath or a steam oven, and has the following advantages. (A) Since it is a vacuum, it has good heat conduction and can be uniformly heated to a specific temperature at which it can be eaten most deliciously. (B) Since it is a vacuum, it has good penetration of seasonings and can be seasoned with a small amount of sugar or salt, which is favorable for health. (C) Since it is vacuum packed, the flavor is not impaired. (D) Since it is heated at a low temperature, the streaks and fibers are not hard but soft. (E) The yield is very high because it is cooked at a temperature that does not cause water division of protein. (F) It can be refrigerated for about one week, which is convenient for large-scale supply such as hotel banquets.

However, in the vacuum cooking operation using hot water, not only the generated steam becomes a source of humidity in the kitchen but also there is a risk of burns and fuel consumption for maintaining the hot water temperature is large. The same applies to vacuum cooking work using a steam oven. Although attempts have been made to use a high-frequency heating device such as a microwave oven as a solution to this problem, it is far from achieving a finishing temperature range of about 1 ° C. required for vacuum cooking, and conventional high-frequency heating means finishes food products. In reality, the temperature range is as high as 20 ° C.

The conventional high-frequency heating means aiming at uniform heating will be described below. They can be roughly classified into four. The first is a means to make the radio wave distribution uniform,
Various means such as stirrer blades and turntables have been devised. The second is a means to shield the radio waves with aluminum foil etc. to prevent the radio waves from concentrating on a part of the food,
Means for thawing frozen food in cold air (US Pat. No.
3536129) and the like for cooling the high temperature portion and the overheated portion to make them uniform. The third is a widely used means generally called Weight-defrost or Weight-cook, which heats by the irradiation power amount and irradiation time of radio waves based on the weight of food, After that, the optimal standing time (stan
(U.S. Pat. No.) for keeping the temperature uniform by heat conduction inside the food by leaving it without radiating radio waves during (ding-time).
4453066) is an example thereof and can be said to be a means without temperature detection.

[0006] Fourth, means for detecting the temperature of the food and controlling the radio wave irradiation, means for using a multi-range thermistor (US Pat. No. 2657580), and the temperature sensor to keep the food below a predetermined temperature. Means of keeping (U.S. Pat. No.
3634652), means for detecting the temperature of a plurality of parts of food, reducing the radio wave output when one of the parts reaches the set temperature, and ending the heating when the other part reaches the set temperature (Japanese Patent Laid-Open No. Sho-06-62). 52-17237) and the like. In addition, as a means combining the above-mentioned third means and fourth means, for example, when thawing a frozen food, the radio wave irradiation is stopped when the surface temperature reaches 5 ° C, and when the surface temperature drops to 0 ° C. Means for estimating the internal temperature from the food surface temperature by detecting the differential value of the time change from 5 ° C to 0 ° C by re-irradiating the radio wave with the electromagnetic wave (JP-A-54-764).
No. 1) has been proposed.

In these conventional high-frequency heating means, the heating end
The difference between the temperature of each part of the food at the end and the desired finish temperature is calculated.
At present, it is difficult to pay even within ℃. Also this
Accurate temperature of each part of food by combining various conventional means
Using computer control such as measurement and predictive control,
For example, even if you try heating to finish at 65 ℃,
Only 65 ℃, other parts are cold without being heated
The result is that it remains. High frequency
The thawing means that gradually reduces the heating irradiation power over time
80 calories of latent heat at 0 ° C was buffered
The meka-thawing process gives relatively good results, but vacuum cooking
Even if applied to, due to various variations, the desired finish temperature
And the temperature difference between each part of the food is also large. Well
In addition, flat foods such as tongue flats have more unevenness.
It is said that it is more intense and is not suitable for high frequency heating.
ing. Also, it can be applied uniformly to specific foods with specific equipment.
Can achieve heat but is non-uniform for any other food
There are many examples in which only heating is possible.

With respect to these conventional techniques, the present inventors proposed
Various means have been tried for the purpose of uniform heating with high frequency.
I have proposed. Of these means, the derivation of the present invention
Related reference means will be described with reference to the drawings.
The structure of the high-frequency heating device used for this reference means
The same as the device used in the embodiment of the present invention described later.
Therefore, the description is omitted here.

The food to be heated has two optical fiber temperature sensors.
Sensor is pushed in, while one is near the highest temperature rise.
It is inserted by the side and its temperature is set to temperature H. Also the other temperature
Insert it in the vicinity of the lowest rise and set its temperature to the temperature L
And Also, the desired finish temperature LT1 of the food to be heated
And the temperature LT2 which is 1 ° C to several ° C lower than the temperature LT1.
It is input to a control means such as a computer and stored. In addition,
The highest temperature part and the lowest temperature part have the same shape of food.
It is possible to know by checking the temperature of each part by heating
Wear. The optical fiber temperature sensors 93 and 94 are heated
It is pushed into food. The optical fiber thermometer is a high-frequency irradiation ring
The temperature can be measured even in the boundary, and the temperature disturbance of the measured system
Less, ie pushed by pushing into food
Compared without the phenomenon of overheating
Accurate temperature measurement is possible.

FIG . 15 is a flow chart showing the operation of the reference means.
It is In Fig., When the start key is pressed,
In step 1, the relays necessary for the heating operation are turned on to set the heating preparation state, and the process proceeds to step 2. In step 2, the temperature H and the temperature L are both the temperature LT2.
It is checked whether the temperature is lower than the temperature L, and as long as both the temperature H and the temperature L are lower than the temperature LT2, the process proceeds to step 3, the triac of the high frequency irradiation source is turned on to heat, and the process returns to step 2. Therefore, when the operation is started from the state where the temperature H and the temperature L are lower than the temperature LT2, the operation is heated by the loop of step 2-3, and this operation is repeated until either the temperature H or the temperature L reaches the temperature LT2. In this case, it may be considered that the temperature H reaches the temperature LT2.

When the temperature H reaches the temperature LT2, the process proceeds to step 4. In step 4, the flag D when selecting ON / OFF of the triac is set to D = 1, so that the heating is prioritized at the time of shifting to step 4. Next, in step 5, it is checked whether the temperature H or the temperature L is lower than the temperature LT2. When both the temperature H and the temperature L are equal to or higher than the temperature LT2, it is determined that the heating process is completed, the process proceeds to step 13, the triac is turned off, and then the relays are turned off in step 14, and all the operations are completed. To do. But,
Otherwise, go to step 6. In step 6, it is checked whether or not both the temperature H and the temperature L are below the temperature LT1 and it is judged whether the temperature is overheated.

If neither the temperature H nor the temperature L is lower than the temperature LT1 in step 6, the process proceeds to step 10 and the flag D is set to D = 0, and D in step 11 is set.
By the flag judgment of = 0, the triac is turned off in step 12 to stop the heating, and the process returns to step 5, but the temperature H
If both the temperature L and the temperature L are equal to or lower than the temperature LT1, the process proceeds to step 7, and either the temperature H or the temperature L is the temperature LT.
Check if less than 2. Temperature H in step 7
Alternatively, if any of the temperatures L is lower than the temperature LT2, the flag D is set to D = 1 in step 8, the process proceeds to step 9 and the triac is turned on to continue heating, and the process returns to step 5, but the temperature H or Either temperature L is temperature L
If it is equal to or more than T2, the process proceeds to step 11, the value of the flag D at that time is determined, the heating in step 9 or the heating stop in step 12 is performed, and then the process returns to step 5.

By the above operation, the process shifts to step 4.
The temperature H, which has reached the temperature LT2 at that time, is determined by the step 4
By the subsequent operation, it is further heated and reaches LT1,
At that point, the triac is turned off and the temperature H rises to LT2.
The triac is turned on again when
Repeatedly heated up to temperature LT1
Is low during the two-point control between LT2 and LT1.
The temperature L of one side goes to LT2 due to heat conduction inside the food.
Rise. Step 5 when the temperature L reaches LT2
It is judged that uniform heating has been completed by
The cooking is finished after passing through the step 14.

Results obtained when heat treatment is performed by this reference means
One example of the fruit is shown in FIG. Fiber optic thermometer
Even if it is pushed into food, only that part is overheated
Since there is no such thing, relatively accurate temperature measurement is possible.
Regardless, the temperature H is the desired finish LT1 = 65 ° C
And the temperature L hardly rises.
It turns out that there are cases where it is not possible. From this,
Uniform heating control only by controlling the temperature H of the high temperature part between two points.
It turned out to be difficult.

[0015]

As described above, the conventional
With the high frequency heating means, the temperature of each part of the food at the end of heating and
The difference from the desired finish temperature can be kept within a few degrees Celsius.
It was difficult.

In addition, the reference means proposed by the proposers
However, there are still insufficient points to achieve uniform heating.
I knew it was.

The present invention solves the above-mentioned problems. In vacuum cooking, the temperature of each part of the food can be heated to within a few degrees at most with respect to the desired finish temperature , and the treatment can be performed .
An object is to provide a simple high-frequency heating method and a high-frequency heating device.

[0018]

According to a first aspect of the present invention, in a high frequency heating process for heating an object to be heated housed in a heating chamber by irradiating it with a high frequency radio wave, a desired finish temperature is θ1, and the desired temperature is from θ1. lower the predetermined temperature .theta.2, the temperature H of the positions previously set as the highest temperature portion of the temperature rise, constantly detects the temperature L of the position set as the lowest temperature portion, one of the temperature H and the temperature L is temperature θ2 before <br/>'re, when the temperature difference between the temperature H and the temperature L is within a predetermined value θ3 is irradiated with high-frequency radio waves, if the temperature difference exceeds θ3 irradiation is stopped Repeat the process ,
Do not maintain the temperature difference between the temperature H and the temperature L within the specified value θ3.
After high-frequency heating , the temperature H does not exceed the temperature θ1 and decreases after either the temperature H or the temperature L reaches the temperature θ2.
High frequency irradiation is intermittent so that the temperature does not fall below θ2
In the process, the high frequency heating is terminated after the temperature L reaches θ2. Further, the present invention according to claim 2 applies a high frequency radio wave to the object to be heated housed in the heating chamber. In the high-frequency heat treatment of irradiating and heating, the temperature change characteristic θ (t) that changes the temperature θ of the object to be heated from the initial temperature θ0 to the desired finish temperature θn by the high-frequency heating for the heating time τ is applied to a hot water bath or a steam oven. Yo
Is defined by an exponential function corresponding to the temperature change characteristic obtained during heating, and the total integrated high frequency irradiation power W (τ) irradiated during the heating time τ is defined as the object to be heated. The temperature rise function Δ (t) = (θ (t) obtained from the temperature change characteristic θ (t) for the change characteristic of the integrated high frequency irradiation power W (t) from the start of heating to time t. ) −θ0) and the total integrated high frequency irradiation power W (τ) is defined as above.
The present invention according to claim 6 is a high frequency heating method in which irradiation is performed by allocating time with the integrated high frequency irradiation power W (t). Further , the present invention according to claim 6 irradiates an object to be heated housed in a heating chamber with high frequency radio waves. In the high-frequency heat treatment, in which the heating target is heated from the initial temperature by high-frequency heating for a heating time τ.
Surface temperature of heated object when changing to the desired temperature
Change characteristics obtained when heated in a hot water bath or steam oven
The exponential function corresponding to the temperature change characteristics
And the total product high-frequency irradiation power W (τ) to be applied during the heating time τ is set corresponding to the object to be heated, and the integrated high-frequency irradiation from the start of heating to time t is set. Whether the change characteristic of the electric energy W (t) is the temperature change characteristic of the polygonal line approximation described above.
The temperature rise function of the line approximation obtained from Δ (t) = (θ (t) −θ
It is specified by the same time function as 0), and the surface temperature is a temperature rise function.
Unit time in the temperature range from the temperature θi to θi + 1 at the intersection of
High-frequency irradiation power per hit is defined in that section
The surface temperature is set to θj (j = j =
0, 1, 2, ..., N-1) from the time of reaching θj +
A high frequency heating method to the operation for irradiating the microwave irradiation power amount per unit time to be sequentially performed for each temperature zone to reach the 1, also claim 12
The present invention according to, comprising: a heating chamber for containing an object to be heated, a high-frequency heating source for irradiating a high-frequency radio wave to the object in the heating chamber, a control unit for controlling the high-frequency irradiation operation of the high-frequency heating source, The control unit is a high-frequency heating device configured to control the heat treatment according to any one of claims 1 to 10 .

[0019]

In the present invention according to claim 1, the object to be heated is
Temperature H of the highest temperature part and the lowest temperature part set in advance
The temperature L of the minute is constantly measured and either the temperature H or the temperature L is measured.
Until the temperature reaches the predetermined value θ2, the temperature between temperature H and temperature L
High frequency irradiation is turned on and off to keep the difference within a specified value.
And heat it so that either the temperature H or the temperature L reaches the specified value θ2.
After the temperature is reached, the temperature H is finished and the desired temperature is set to θ1
Turn on the high frequency irradiation so that it is between the two points with the temperature θ2.
Turn off the high frequency heating after the temperature L exceeds the temperature θ2.
Finish.

In the present invention according to claim 2, the temperature characteristic of the object to be heated is determined by heating with a hot water bath or a steam oven.
Specify the exponential function corresponding to the obtained temperature characteristic, set the change characteristic of the integrated high frequency irradiation power based on the temperature rise function calculated from it, and distribute the total integrated high frequency irradiation power over time to perform irradiation. To do.

In the present invention according to claim 6, the change characteristic of the integrated high frequency irradiation power amount and the high frequency irradiation power amount per unit time are defined based on the surface temperature rising function defined in each temperature interval, and each temperature interval is defined. In step 1, high-frequency radio waves are radiated until the surface temperature at the end point of the section is realized under the conditions defined in that section, and the operation moves to the next temperature section.

In a twelfth aspect of the present invention, the control section executes each of the above heating methods.

[0023]

Embodiment 1 Hereinafter, an embodiment of the present invention according to claim 1 will be described with reference to the drawings. In this claim 1
The present invention concerned is an effective means of uniform heating, and
Including the important elemental technology leading to the present invention according to claim 2
It is a waste.

FIG. 1A is a perspective view showing the structure of the high frequency heating apparatus of this embodiment, and FIG. 1B is a sectional view taken along the line AA '. In FIG. 1A, 11 is a heating chamber made of stainless steel, 12 is a food placing table made of crystal glass fixed to the bottom of the heating chamber 11, 13 is a door that closes the opening of the heating chamber 11,
Reference numeral 14 is an operation unit provided on the upper front surface of the apparatus, and reference numeral 15 is an outer box forming an outer wall of the apparatus.

Further, in FIG. 1 (b), 16 is an oil mat placed on the food placing table 12, 17 is a net of a cage placed on the oil mat 16, and 18 is an inside of the net 17 of a cage. A multi-core shield wire for electrically connecting a temperature sensor (not shown) provided in the, a metal plug 19 connected to one end of the multi-core shield wire 18, and 20 fixed to the rear wall of the heating chamber 11. It is a metal connector. For example, RS-2 used in personal computers
A 32C plug and connector may be used. It should be noted that in the present embodiment, the temperature measurement by the cage net 17 is not performed, and therefore, the description will be given in the second embodiment. Reference numeral 21 is a food to be heated placed on the mesh net 17 of the cage, and 22 is an oil mat placed so as to cover the food 21 to be heated. 23 is the heating chamber 11
Resin stirrer cover on top of the, 24 and 2
6 is an antenna, 25 and 27 are rotation motors for rotating the antenna 24 and the antenna 27, respectively, and 28 is the heating chamber 1.
1 is a waveguide provided on the upper side, 29 is a waveguide provided under the heating chamber 11, 30 is a magnetron provided at one end of the waveguide 28, 31 is a magnetron provided at one end of the waveguide 29. is there.

Reference numeral 32 is a fan motor for forcibly cooling the magnetron 30, 33 and 40 are a group of small holes provided on the back wall surface 38 of the outer box 15 for discharging the hot air in the heating chamber 11 to the outside, and 35 is a fan. A group of small holes for introducing the cold air by the motor 32, a group of 36 for discharging the cold air introduced from the group of small holes 35 into the heating chamber 11, a reference numeral 37 for an exhaust guide, and a reference numeral 39 for introducing the cool air from the outside. This is a group of small holes provided on the bottom wall surface of the outer box 15 for this purpose.

FIG. 2A is a perspective view showing the structure of the oil mat 16 and the oil mat 22, and FIG.
It is a C'cross section. In the figure, 80 is a polyethylene layer having a thickness of about 50 microns, and 81 is a nylon layer having a thickness of about 20 microns, which form a rectangular bag 82. Reference numeral 83 is a edible oil such as a commercially available salad oil enclosed in a rectangular bag-like container 82, and 84 is a heat-sealed portion.

FIG. 3 is a circuit diagram showing the structure of the high frequency heating apparatus used in this embodiment. In addition, in the reference means
Also uses the same device. In the figure, 25 and 27 are antenna rotation motors that rotate antennas that output high-frequency radio waves, 30 and 31 are magnetrons that oscillate high-frequency waves, 51 is a power plug, and 32 and 58 are fan motors for cooling magnetrons, respectively. Is a fuse, 53 is a noise filter coil, 54 is a lamp for illuminating the heating chamber, 55 is a relay for opening and closing the lamp 54, 5
Reference numeral 6 is a magnetron heater transformer, 57 is a relay for opening and closing the heater transformer 56, 60 and 61 are switches for interlocking with opening and closing of a heating chamber door, 62 and 63 are main relays, 64 and 65 are short switches, respectively. 66 and 67 are triacs, 68 and 69 respectively
Are high voltage transformers, 70 and 71 are trigger circuits, 90 is a personal computer (hereinafter referred to as a personal computer) that controls the operation of the apparatus, 91 is an RS-232C cable connected to the personal computer, 92 is an optical fiber thermometer, and 93 And 94 are optical fiber temperature sensors. The optical fiber temperature sensors 93 and 94 are pushed into the food to be heated. The optical fiber thermometer can measure the temperature even in the high frequency irradiation environment, and the temperature fluctuation of the system to be measured is small, so even if it is pushed into food, the phenomenon of overheating only the pushed portion does not occur, and it is relatively Accurate temperature measurement is possible. One of the optical fiber temperature sensors 93 and 94 is inserted in the vicinity of the portion where the temperature rise is highest, and the temperature is set to the temperature H. Further, another is inserted near the portion where the temperature rise is the lowest, and the temperature is set as the temperature L. In addition, the desired finish temperature LT1 of the food to be heated and 1 from the temperature LT1
Enter the temperature LT2 which is ℃ to several ℃ lower into the personal computer and store it. These conditions are the same as those of the reference means described in FIG.

FIG. 4 is a flow chart showing the operation of this embodiment. The operation after step 4 is the reference means described above.
Since the operation is the same as that of 1., detailed description will be omitted. The processing operation of this embodiment is different from the processing operation of the reference means shown in the flowchart of Fig. 15, in the first half of the processing, the step 15 of checking the temperature difference between the temperature H and the temperature L is performed.
And step 16 of turning off the triac according to the result .

In FIG. 4, when the start key is pressed, all relays (55, 57, 6
2 and 63) are turned on to set the heating preparation state, and the process proceeds to step 2. In step 2, it is checked whether both the temperature H and the temperature L are lower than the temperature LT2,
If either temperature H or temperature L is above temperature LT2
Unless otherwise, go to step 15. In step 15,
It is checked whether or not the difference between the temperature H and the temperature L is lower than 20 ° C., and if the temperature difference is smaller than 20 ° C., the process moves to step 3, and the trigger circuit 70 causes the triac 66 and the trigger circuit 71 to cause the triac 66. 67 is turned on and heating is started, and the process returns to step 2, but the temperature difference is 2
When the temperature becomes 0 ° C. or higher , the process proceeds to step 16, the triac is turned off to stop heating, and the process returns to step 2. Therefore, when the operation is started from the state where the temperature H and the temperature L are lower than the temperature LT2, the temperature is heated by the loop of step 2-15-3, but the temperature difference between the temperature H and the temperature L is 20 ° C.
In the above case, the heating is interrupted by the loop of step 2-15-16, and the temperature difference is reduced due to the heat conduction inside the object to be heated. By repeating this operation, the heating is continued while the temperature difference is smaller than 20 ° C., and the temperature H
Alternatively, one of the temperatures L reaches the temperature LT2. In this case, it may be considered that the temperature H reaches the temperature LT2.
When the temperature H reaches the temperature LT2, the process proceeds to step 4. The subsequent processing is the same as that of the reference means shown in FIG.

FIG. 5 is a characteristic diagram showing the relationship between time and temperature when about 900 g of pork refrigerated at about 0 ° C. to 5 ° C. is heated to the desired temperature LT1 = 65 ° C. by the above heat treatment. is there. In this case, LT1 = 65 ° C, L
Input T2 = 64 ° C. Moreover, 500g of salad oil is sealed in a bag about 23cm wide and about 30cm long with a film about 0.1mm thick to form a plate-like oil mat about 1cm thick, sandwiched from the top and bottom of pork. It was used by being sandwiched between. The heating time was 2 hours and 30 minutes, and the integrated power value measured on the primary side of the driving transformer was 136.
Wh, the temperature of each part of pork is between 64 ℃ and 66 ℃. In addition, the temperature rise data when 900g of pork was vacuum-cooked to 65 ° C in about 2 to 2.5 hours by a steam oven is also shown in Fig. 5. Compared with that, the high-frequency heating of this second reference means It can be seen that cooking by treatment is almost the same as vacuum cooking by a steam oven.

[0032] The processing result of this embodiment, shown in FIG. 15 ginseng
Compare with the processing result of the consideration means . FIG. 16 is a characteristic diagram showing the processing result of the reference means and the processing result of the present embodiment in comparison. In the reference means , as shown in FIG.
Although the temperature L hardly rises, the temperature H is 6
It has greatly exceeded 5 ° C. Therefore, for example, the temperature L
If T1 is set to 40 ° C. and the processing is such that the high frequency irradiation is stopped when the temperature reaches about 40 ° C., FIG.
As shown in, the phenomenon in which the temperature exceeds 65 ° C. can be prevented, but the temperature L does not rise. On the other hand, as in the present embodiment, if the high frequency irradiation is performed only when the difference between the temperature H and the temperature L is within 20 ° C., for example, FIG.
As shown in FIG. 3, uniform heating is possible so that the difference between the temperature H and the temperature L and the desired finish temperature LT1 is within 1 ° C.

[0033] Thus, high-frequency heating treatment of the present embodiment for controlling the temperature difference between the temperature H and the temperature L to 20 ° C. to consider the reason for resulting in good results. The specific heat of pork is about 0.3
5. Since the specific heat of salad oil can be estimated to be about 0.4, the total heat of about 900 g of pork and the oil mat corresponds to about 715 cc of water. The amount of heat required to raise this from 5 ° C to 65 ° C is 429000 calories,
When this is divided by 860 and converted into electric energy, it becomes 49.8wh. On the other hand, of the integrated electric energy of 136 wh on the primary side of the high voltage transformer 68 and the high voltage transformer 69, the ratio of being absorbed by the object to be heated as the high frequency irradiation electric energy was about 53% in the tested device . Therefore , 72.0wh
Is considered to be the high frequency irradiation power. That is , 49.8
It is /72.0=69.1, and it can be interpreted that about 70% of the amount of electric power was absorbed by the object to be heated and the other 30% or more was lost.

FIG. 5 shows the temperature H of the highest temperature part and the lowest temperature.
Characteristics of the temperature L of the part and the accumulated electric energy of 136wh
FIG . However, since the temperature and the electric energy have different dimensions, the scale is forcibly matched with 136wh = 65 ° C. According to FIG. 5, it can be seen that the change characteristic of the integrated electric energy and the change characteristic of the temperature L, which is the lowest temperature portion of the pork, are on almost the same curve. In order to confirm whether this phenomenon is universal, 100g, 200g, 500g and 800g of beef minced meat packed in a meatloaf type and vacuum packed as other foods.
The same oil mat 2 as in the previous embodiment with four weights of g
It is sandwiched between the sheets, and the process of the flowchart shown in FIG.
The result of heating to 8 ° C. is shown in the characteristic diagram of FIG. From this result, it can be said that the similar relationship between the integrated electric energy and the change in the lowest temperature part is a universal phenomenon.

Table 1 summarizes the relationship between the input electric energy (integrated electric energy) and the absorbed heat energy (electric power conversion) of the food to be heated in the above high frequency heating.

[0036]

[Table 1]

In Table 1, the first row shows the total heat of meat and oil mat when the specific heat of beef is about 0.43,
The second line is the amount of heat of water of the same weight as the meat, which is assumed to be the amount of absorbed heat, the third line is the integrated electric energy on the primary side of the transformer, and the fourth line is the integrated high-frequency irradiation power applied to the heating chamber. Is the amount. In order to convert the integrated power amount into the integrated high frequency irradiation power amount, the water load amount characteristic of the conversion efficiency between the integrated power amount and the integrated high frequency irradiation power amount shown in FIG. 7 is used. Although the description of the absorbed heat amount is omitted, there is a similar tendency when the oil mat is not used. The fifth line is the value of (heat quantity of water equivalent to meat) / (integrated high frequency irradiation power quantity), which falls within the range of 66% to 88%. That is, the integrated electric energy is about 25% on average.
The loss may be absorbed by the equivalent amount of water in the meat.

To summarize the above considerations, the amount of heat required to finish the same amount of water as the food to be heated and raise it to the desired temperature is 25
Similar to the steam oven by applying high frequency irradiation power with a heat amount of about% and irradiating the time required for vacuum cooking in the steam oven with time distribution along the temperature rise curve of the central part. It is thought that the uniform heating of is possible .

As described above, the internal temperature difference is more than 20 ° C.
High frequency irradiation and irradiation stop are repeated to make it smaller
The example is irradiation when the food to be heated is partially overheated.
To stop the heat transfer
Equivalent to heat conduction-based heating that follows an exponential function like cooking
Of high frequency heating, and derived from it
As a result, the integrated high frequency irradiation power is almost exponential.
Means of time allocation according to pattern become uniform heating means
I found it to be connected .

In this embodiment, the temperature H or
After one of the temperatures L reaches the temperature θ2,
When controlling H between two points between temperature θ1 and temperature θ2
However, the temperature H does not exceed the temperature θ1 and at least
It suffices to heat it so that it does not fall below the temperature θ2.
Therefore, the temperature H is controlled at 1 point to the temperature θ1 for heating.
Then, in the process, the temperature L becomes the temperature θ2 due to the internal heat conduction.
It is also possible to stop heating after reaching
Needless to say.

(Embodiment 2) An embodiment of the high-frequency heating method and the high-frequency heating apparatus of the present invention according to claim 2 will be described below with reference to the drawings. In addition, this embodiment
The configuration of the high-frequency heating device is the same as that of the first embodiment,
Description is omitted. However, in this embodiment, an optical fiber
The temperature sensors 93 and 94 are not used.

In Example 1, high-frequency irradiation was performed while controlling the internal temperature difference and the temperature of the highest temperature part by using an optical fiber temperature sensor, so that the temperature change characteristics near the central portion cooked in a steam oven or hot water were obtained. Although it was possible to heat with the same pattern, the degree of vacuum is lowered because the resin bag of the vacuum pack is penetrated to insert the optical fiber temperature sensor into food. Further, it is very difficult to pierce the packing with sponge-like adhesive, which is used for preventing the reduction of the degree of vacuum , with the weak optical fiber temperature sensor.

This embodiment provides means for not using the optical fiber temperature sensor to solve the above problems. As described in the discussion of Example 1 , when uniform high-frequency heating equivalent to cooking with a steam oven or hot water was achieved,
The time distribution of the total integrated high frequency irradiation power was the same as the characteristic curve of the temperature rise value when cooking in a steam oven or hot water bath. Based on the above consideration results, the present Example, the integrated high-frequency irradiation power required to raise the heated food to a predetermined temperature, the same as the characteristic curve of the temperature rise value when cooked by a steam oven or hot water It is a means to realize uniform heating by allocating time to the above, and does not require an optical fiber temperature sensor.

In this case, if the temperature change characteristic can be made into a time function, it is convenient for the calculation of time distribution. When the temperature change characteristic of cooking by the steam oven or hot water is made into a function, an exponential function that gives the following Newton's cooling law can be applied.

(Θw−θ) / (θw−θ0) = exp (−kt) where θw: hot water temperature of hot water or steam oven temperature θ: internal temperature of food to be heated θ0: food to be heated Initial temperature k: Proportional constant (values differ between boiling water and steam oven) t: Elapsed time. The above formula gives the characteristic that when the food to be heated whose initial temperature is θ0 is left in an atmosphere of temperature θw, the food to be heated is cooled toward the temperature θw when θw <θ0. When θw> θ0, the property of being heated toward the temperature θw is given. Also, when θw = θ0, there is no temperature change, so it corresponds to the storage state. FIG. 8 shows the measured value of the internal temperature rise value when 900 g of pork was vacuum-cooked in a steam oven, and the calculated temperature rise value (θ−θ0) when an appropriate value of k was substituted into the above equation. It is a characteristic diagram compared. Although there was a slight difference in the initial stage of heating, they were almost the same, and it was confirmed that an exponential function that gives the Newton's cooling equation can be applied. Therefore, along the function of the temperature rise value derived from the above exponential function, the amount of heat (integrated high frequency irradiation power)
It is thought that if heating is added in a timely manner, uniform heating like a steam oven or hot water can be realized without using an optical fiber thermometer.

This embodiment will be described below with reference to the drawings. FIG. 9 is a flow chart showing the operation of the heat treatment of this embodiment. Note that this heat treatment can be carried out by a high frequency heating device except the optical fiber thermometer from the configuration shown in FIG.

The program is started, and in step 1, the weight of the food to be heated (hereinafter referred to as w), and in step 2, the desired finished temperature rise value θ (desired food finish temperature θn
(A value obtained by subtracting the initial temperature θ0 from the above), and the heating time τ spent for the temperature rise value θ in step 3 is input to the personal computer 90. Next, in step 4, the number n0 of times of irradiation is calculated by temporally distributing the necessary integrated high-frequency irradiation electric energy to be applied to the heating chamber. It is ideal that the integrated high-frequency irradiation power is continuously distributed in time according to the exponential function, but the device configuration becomes complicated. Therefore, the time is distributed stepwise by a combination of short-time irradiation and irradiation stop, and the number of repetitions is set to n0.

First, based on the above consideration, the integrated high-frequency irradiation power is calculated by multiplying the food weight w by the desired temperature rise value θ, multiplying it by 1.25 in consideration of the aforementioned 25% loss, and dividing by 860. Convert to quantity and obtain. Next, the electric energy is divided by the nominal high-frequency output value (rated output value) to calculate the cumulative irradiation time, which is multiplied by 3600 and converted to the unit of seconds. Further, the irradiation time is set to 3 seconds according to the experimental result, and the high frequency irradiation power amount during that period is set to be constant. Therefore, the number of irradiations n0 is calculated by dividing by 3. The remainder will be discarded. The irradiation time of 3 seconds is a value according to the capability of the irradiation device, and it is important that the irradiation time is too long and partial overheating does not occur. It is a value that should be determined in consideration of the fact that the partial heat generation is made uniform by the heat diffusion inside the food.

[0049] then proceeds to step 5, to allocate n0 times the heating time τ according to the equation of the exponential function, if
For example, substituting the time required to reach a temperature 1 ° C lower than the desired temperature as τ, the first time t1 = log (1-1 / n0) / (1 / τ · log (1 / θ) nth time tn = log (1- n / n0) / (1 / .tau.log (1 / .theta.)), and these times are calculated up to (n0-1) th time and stored. ..

Next, in step 6, the operator places the food to be heated in the heating chamber and waits for the start key to be pressed. When the start key is pressed, the process proceeds to step 7 to turn on the relays 55, 57, 62 and 63, and the process proceeds to step 8 where undefined t0 is set to 0 and the counter is set to n = 0. Next, the routine proceeds to step 9, where the elapse of time after the start key is pressed is constantly checked, and when the count value n of the number counter reaches the specified tn time, the routine proceeds to step 10. Step 10
At, the triac is turned on, the process proceeds to step 11, waits until the elapsed time reaches (tn + 3) seconds, then the process proceeds to step 12, and the triac is turned off. Heating is performed for 3 seconds in steps 10-11-12.

Next, in step 13, the count value n of the number counter is incremented by 1 to (n + 1), and in step 14, it is checked whether the n value is less than (n0-1). To do. If it is less than the above, it is determined that the processing has not been completed, the process returns to step 9, and the same operation is repeated.
If it is (n0-1), it is determined that the processing is completed, and the routine proceeds to step 15, where the relays 55, 57, 62 and 63 are turned off and the processing is ended.

As described above, according to the present embodiment, the temperature change characteristic of the food to be heated in the cooking by the steam oven or the hot water is set, and the total integrated high frequency irradiation electric energy is time-divided and irradiated in the same pattern. As a result, uniform heating equivalent to cooking with a steam oven or hot water can be realized without using a temperature sensor.

In this embodiment, the conversion efficiency between the input power and the high-frequency irradiation power is assumed to be 25%, but it depends on the material and shape of the food, the weight and shape of the oil mat, the contact condition between the food and the mat, etc. It is not limited to 25%. Further, although the high frequency irradiation time is set to 3 seconds, it goes without saying that it may be set to a time that does not cause overheating due to the irradiation capacity of the apparatus.

The heating time τ depends on the steam oven and hot water.
There is no need to set the same as the cooking time by roasting, but rather
Needless to say that you can set the heating time to a significantly shorter value.
Nor. The reason is steam orb in vacuum cooking
The food and water boiled through the vacuum pack that prevents heat conduction.
In contrast to high-frequency heating, food is heated directly.
Because it is done. Also, heat source of steam oven or hot water
The temperature is 100 ℃, but it is equivalent in high frequency heating
This is because the temperature can be raised to 100 ° C or higher. In any case,
Apply different exponential function than steam oven or hot water
By doing so, cooking time is better than steam oven or hot water
It can be shortened.

Although the case where the integrated electric energy is distributed in time in accordance with the temperature rise function has been described, the function may be approximated by a polygonal line or a combination of a polygonal line and a curve. In the case of approximation, the heating time may be shortened by allocating a large amount in the first half of the heating time and a small amount in the latter half of the heating time so that they match at the end point.

The reason why a large amount may be allocated in the first half is
From the outside via a vacuum pack in a team oven or hot water
Since it is heating of the food, it takes time to raise the food temperature
Therefore, in high frequency heating, which is direct heating,
Uniform even if the product temperature is raised more quickly than boiling water
This is because it does not hinder heating.

(Embodiment 3) An embodiment of the high frequency heating method and the high frequency heating apparatus of the present invention according to claim 6 will be described below. In Example 2, the conversion efficiency with respect to the input power was assumed to be 25% in order to determine the integrated high frequency power, but as described above, the value of the conversion efficiency depends on the material and shape of the food, the weight and shape of the oil mat, It depends on the contact condition between the food and the mat, etc., and many trials are required before it is possible to determine the integrated high-frequency power amount that achieves favorable results in terms of finishing temperature and uniformity.

The present embodiment is a means for solving the above-mentioned problems, and is different from the second embodiment in that the temperature rise value is checked during heating.
There is a point to check. Moreover, the temperature is not the internal temperature,
Check the surface temperature. Also, the temperature change characteristics of the heated object
Is approximated by a polygonal line.

[0059] The point of this example, the temperature change especially of the heated object
The characteristics are approximated by polygonal lines, and heating is performed with the high-frequency heating amount per unit time corresponding to each linear expression, and when the intersection temperature of the polygonal lines is reached, heating is performed with the high-frequency irradiation electric energy per unit time corresponding to the next linear expression. Move to operation. After performing this operation for each broken line, heating is terminated. in this case,
The microwave irradiation power per unit time, in the same manner as in Example 2, but determined by the period operation by the irradiation pausing the microwave irradiation for a predetermined time according to the temperature rise function, irradiation pausing time in one straight section is a naturally constant value . However, the number of times of irradiation is not defined as in Example 2, and the irradiation is repeated until the measured surface temperature reaches the intersection temperature of the polygonal lines. By this temperature control, the heating accuracy is improved as compared with the means of the second embodiment in which the integrated high frequency irradiation power amount and its time distribution are defined in advance. In addition, although the internal temperature of the object to be heated is not measured in this example, since it is high frequency heating based on an exponential function , partial overheating is suppressed and uniform heating is performed, and the surface temperature is measured instead of the internal temperature. Characteristic that it is enough
Is .

This embodiment will be described below with reference to the drawings. First, prior to the description of the heating method, the surface temperature measuring means used in this example will be described. Figure 1
0 (a) is a perspective view showing the configuration of the cage net 17 used in this embodiment, and FIG. 10 (b) is a BB 'sectional view thereof.
In the figure, 41 is a frame-shaped frame made of a metal round bar,
42 is a rod-shaped body made of a hollow circular metal inserted and fixed in holes provided on the front side and the rear side of the frame 41, 43 is a thermistor provided inside the hollow of the rod-shaped body 42, and 44 and 45 are frames. Four
1 is a pair of mounting metal fittings fixed by a fixing screw 46 with the rear side of 1 interposed therebetween. In addition, 18 is a multi-core shielded wire for connecting the thermistor 43, and 19 is a metal plug. The rod-shaped body 42 is, for example, a metal tube having an inner diameter of 1.3 mm and a wall thickness of about 0.18 mm made by the same manufacturing method as an injection needle, and is fixed to the frame 41 and then plated with nickel.
The thermistor 43 is inserted into the hollow inside of the rod-shaped body 42, and its two lead wires are insulated at least in the area located inside the rod-shaped body 42, and the frame 41 and the mounting brackets 44 and 45.
It is electrically connected to one of the core wires of the multi-core shield wire 18 in the triangular space formed by. Also, the mounting bracket 44
And 45 are provided with a concave portion in the center, and at this portion, the metal core of the multi-core shielded wire 18 is electrically connected. The thermistor 43 and its lead wires are rod-shaped body 42, mounting bracket 44
And 45, metal jacket of shielded wire and metal plug 1
9 and electrostatically shielded. In this embodiment, the thermistor 4
Seven rods 3 are used, and among the seventeen rod-shaped bodies 42 shown in FIG.

FIG. 11 is a circuit diagram showing the structure of the high frequency heating apparatus of this embodiment. The same components as those of the circuit configuration shown in FIG. 3 are assigned the same reference numerals and detailed explanations thereof will be omitted. Further, FIG. 12 is a circuit diagram showing a configuration of the control circuit 72. In FIG. 12, 73 is a power transformer, 74 is a microprocessor for controlling the operation of the control circuit 72, and 75 is
Is a transistor that shapes the AC waveform on the secondary side of the power transformer 3 and outputs it to the port P8 of the microprocessor 74; 76 is the load resistance of the thermistor 43; and P1 to P7 are input terminals with A / D conversion function of the microprocessor 74. ,
P9 to P14 are output terminals of the microprocessor 74, and are connected to the relays 55, 57, 62 and 63 shown in FIG. 3 and the triac trigger circuits 70 and 71 shown in FIG. 3 via diodes and transistors. The microprocessor 74 inputs the output voltage of the temperature sensor 43 provided in the cage net 17 to detect the surface temperature of the object to be heated, and controls the operations of the magnetrons 30 and 31 by the trigger circuits 70 and 71.

The heating method of this embodiment will be described below. In this embodiment, the temperature change characteristic is shown in FIG.
It is approximated by three straight lines with reference to the characteristic diagram shown in FIG.
Now, according to the heating time = τ , the food to be heated is changed from the initial temperature.
When heating to a constant finishing temperature , the temperature change curve on the characteristic diagram shows a point of τ / 10 of heating time and 3τ /
Since it can be regarded as passing through 10 points, the temperature change curve is approximated by three straight lines having these two points as intersections. Further, in each straight line, the high frequency irradiation time is set to 3 seconds and the irradiation stop time is set to A, B, and C seconds, respectively, and is determined in the following processing steps.

The operation of this embodiment will be described below.
13 and 14 are flowcharts showing the operation of this embodiment. Note that, in FIG. 13, up to step 4 for obtaining the irradiation number n0 is the same as the flowchart shown in FIG. 9, and description thereof will be omitted. The purpose of obtaining the number of irradiations n0 is to use the approximate straight line as a standard temperature change characteristic and to determine the amount of high frequency irradiation power per unit time corresponding to the slope thereof. Note that it is not for regulation. Next, step a
The irradiation stop time A is calculated in. The irradiation stop time A is determined by dividing (τ / 10) by (n0 / 3), discarding the remainder, and then subtracting 3 seconds. Next, in step b, the irradiation stop time B is similarly determined. Divide (3τ / 10) by (n0 / 3), discard the remainder, and subtract 3 seconds to determine. Next, in step c, the irradiation stop time C
To decide. The irradiation stop time C is determined by dividing (τ-3τ / 10) by (n0 / 3), discarding the remainder, and then subtracting 3 seconds. Next, the process proceeds to step d in the flowchart shown in FIG.

In step d, each relay for starting operation is turned on, and in step e, high frequency irradiation is performed in step f while confirming that the temperature rise value detected by the food surface temperature detecting means does not reach T3 = T / 10. 3
The periodic operation of turning on for seconds and turning off for A seconds is repeated . Here, T is the temperature at which the food to be heated reaches the finish temperature.
Sometimes the output value T1 measured by the food surface temperature detection means
Value obtained by subtracting the output value T0 when the food is at the initial temperature
Is. Scan temperature rise value in step e is shifted to step g reaches the T3, the temperature rise value is T2 = 3 T / 1
While confirming that 0 is not reached, in step h, the high frequency irradiation is turned on for 3 seconds and turned off for B seconds, and the periodic operation is repeated. In step g, the temperature rise value is T2
When the temperature rise value reaches T1
In step j, the high frequency irradiation is turned on for 3 seconds and turned off for C seconds, and the cyclic operation is repeated while confirming that the value does not reach. When the temperature rise value reaches T1, the process proceeds to step k, all relays are turned off, and the heating process ends. As a result of the above heat treatment, the result that the difference from the desired finish temperature was within 1 ° C. was obtained as in Example 1.

As described above, according to the present embodiment, the function of the temperature change characteristic of the food to be heated is approximated by three straight lines,
Determine the high frequency irradiation power per unit time corresponding to the function of each straight line, irradiate the high frequency while measuring the surface temperature of the food to be heated, when the temperature at the intersection of the polygonal line is reached, the unit corresponding to the next straight line the operation of irradiating with microwave irradiation power amount per hour, and performed for each straight line, by high-frequency heating treatment of the surface temperature of the process to a predetermined value, the amount of irradiation by estimation error and the linear approximation of the amount of power Error is compensated, and it is possible to achieve a finish temperature and uniform heating that are equivalent to those obtained by heating with a steam oven or boiling water.

In the embodiment, heating by three linear approximations has been described, but it goes without saying that the processing accuracy can be improved by further increasing the number of polygonal lines and combining curves and straight lines. Further, in the present example, the temperature of the object to be heated was measured by the surface temperature, but since the high frequency irradiation based on the exponential function is performed, temperature uniformity is realized and the temperature difference between the inside and the inside temperature is small. It is no longer necessary to measure. However, it goes without saying that the internal temperature may be measured. Also,
When measuring the surface temperature, it is effective to consider the temperature gradient between the cage and the internal temperature sensor, and when measuring the surface temperature by inserting an optical fiber thermometer between the oil mat and the object to be heated. It is the same. Also, increase the high frequency irradiation power per unit time in the first linear approximation,
The second and subsequent straight lines may be irradiated with a small amount so that they coincide with each other at the end point.

[0067]

As is apparent from the above embodiments, the present invention according to claim 1 is completed in the high frequency heat treatment for irradiating and heating the object to be heated housed in the heating chamber with high frequency radio waves. the desired temperature .theta.1, said and θ2 a predetermined temperature lower than the temperature .theta.1, constantly detects the temperature H of the preset position, and the temperature L of the position set as the lowest temperature portion as the highest temperature portion of the temperature rise, the temperature until one of H and temperature L is reach the temperature θ2, when the temperature difference between the temperature H and the temperature L is within a predetermined value θ3 is irradiated with high-frequency radio waves, if the temperature difference exceeds θ3 Repeats the process of stopping the irradiation to determine the temperature difference between the temperature H and the temperature L by a predetermined value.
High frequency heating is performed while maintaining the value within θ3, and after either the temperature H or the temperature L reaches the temperature θ2 , the temperature H is increased.
Do not exceed θ1 and do not drop below temperature θ2
High-frequency irradiation was intermittently started, and the temperature L reached θ2 in the process.
Since the high frequency heating is terminated after that, the present invention according to claim 2 is characterized in that the heating time τ is increased in the high frequency heating process in which the object to be heated housed in the heating chamber is irradiated with high frequency radio waves to heat the object to be heated. The temperature change characteristic θ (t) that changes the temperature θ of the object to be heated by the high frequency heating from the initial temperature θ0 to the desired finish temperature θn is calculated by using a boiling water or a steam orb.
Index corresponding to the temperature change characteristics obtained when heating with
The total integrated high frequency irradiation power W (τ) to be applied during the heating time τ is set corresponding to the object to be heated, and the integrated high frequency irradiation power W (t) from the start of heating to time t ( t) is the change characteristic of the temperature change characteristic θ (t)
Is defined based on the temperature rise function Δ (t) = (θ (t) −θ0) obtained from the above, and the total integrated high frequency irradiation power W (τ) is
Since the irradiation is performed by time distribution with the specified integrated high-frequency irradiation power W (t) , the present invention according to claim 6 irradiates the object to be heated housed in the heating chamber with high-frequency radio waves. Heating time τ in high-frequency heat treatment for heating
The high-frequency heating finish the object to be heated from an initial temperature
Change of the surface temperature of the object to be heated when changing to the desired temperature
The characteristics obtained when heated in a hot water bath or steam oven
The exponential function corresponding to the temperature change characteristic is approximated to a polygonal line , and the total integrated high-frequency irradiation power W (τ) to be applied during the heating time τ is determined according to the object to be heated. Set and cumulative high-frequency irradiation power W from heating start to time t
The change characteristic of (t) is calculated from the temperature change characteristic of the line approximation described above.
Obtained polygonal line approximation temperature rise function Δ (t) = (θ (t) −θ
It is specified by the same time function as 0), and the surface temperature is a temperature rise function.
Unit time in the temperature range from the temperature θi to θi + 1 at the intersection of
High-frequency irradiation power per hit is defined in that section
The surface temperature is set to θj (j = j =
0, 1, 2, ..., N-1) from the time of reaching θj +
The operation of irradiating with the high-frequency irradiation power amount per unit time is sequentially executed for each temperature section until the temperature reaches 1, and the present invention according to claim 12 accommodates an object to be heated. A heating chamber, a high-frequency heating source for irradiating the object to be heated with high-frequency radio waves, and a control unit for controlling the high-frequency irradiation operation of the high-frequency heating source,
Since the control unit controls the heat treatment according to any one of claims 1 to 10 , uniform heating similar to cooking with a steam oven or hot water can be realized by high-frequency heat treatment , and direct heating is also possible. Some high frequency
Select an exponential function that takes advantage of the characteristics of heating,
By increasing the distribution of irradiation energy in the first half,
Cooking in a shorter time than cooking with an oven or boiling water is also possible
Becomes

In the embodiments, the vacuum cooking is described, but it is also effective for non-vacuum foods.
It is also effective in thawing frozen foods. Further, it can be used not only for foods but also for heating other objects to be heated, for example, heating resin products.

[Brief description of drawings]

FIG. 1A is a perspective view showing a configuration of an embodiment of a high-frequency heating apparatus of the present invention, and FIG. 1B is a sectional view taken along the line AA ′.

FIG. 2 (a) is a perspective view showing the configuration of an oil mat used in the high-frequency heating device of the present invention (b) its BB ′ sectional view

FIG. 3 is a circuit diagram showing a configuration of an embodiment of the reference means and the high-frequency heating device used in the first embodiment.

FIG. 4 is a flowchart showing the operation of the high frequency heating method according to the first embodiment.

FIG. 5 is a characteristic diagram showing a treatment result by the high frequency heating method of Example 1.

FIG. 6 is a characteristic diagram showing another processing result of the first embodiment.

FIG. 7 is a characteristic diagram showing an example of conversion efficiency between input power and irradiation power.

[Figure 8] Based on the measured value and exponential function of the temperature rise value of food
Characteristic diagram showing the relationship with calculated values

FIG. 9 is a flowchart showing the operation of the second embodiment of the present invention.

FIG. 10 (a) is a perspective view showing the structure of a cage of the present invention. FIG.

FIG. 11 is a circuit diagram showing the configuration of an embodiment of the high-frequency heating device of the present invention.

FIG. 12 is a circuit diagram showing a configuration of the control circuit.

FIG. 13 is a partial flowchart showing the operation of the high frequency heating method according to the third embodiment of the present invention.

FIG. 14 is a partial flowchart showing the operation of the high frequency heating method according to the third embodiment of the present invention.

FIG. 15 is a flowchart showing the operation of the high-frequency heating method of the reference means.

16A is a characteristic diagram showing an example of a treatment result of a conventional high-frequency heating method. FIG. 16B is a characteristic diagram showing another example of a treatment result of a high-frequency heating method by a reference means . FIG. 16C is a high-frequency heating method of the present invention. Of characteristics showing the processing results of Example 1 of

[Explanation of reference numerals] 11 heating chamber 17 baby cub (surface temperature measuring means) 21 food to be heated (object to be heated)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H05B 6/64 6908-3K

Claims (20)

[Claims] 1. In a high-frequency heating process in which an object to be heated housed in a heating chamber is irradiated with high-frequency radio waves for heating, a desired finishing temperature is θ1, a predetermined temperature lower than the temperature θ1 is θ2, and the highest temperature rise portion. The temperature H at the position specified in advance and the temperature L at the position specified as the lowest part
And the temperature difference between the temperature H and the temperature L is within a predetermined value θ3, high frequency radio waves are emitted unless either the temperature H or the temperature L reaches the temperature θ2. When the temperature difference becomes θ3 or more, the process of stopping the irradiation is repeated, and after either the temperature H or the temperature L becomes the temperature θ2 or more, either the temperature H or the temperature L reaches the temperature θ1. Unless either the temperature H or the temperature L is lower than the temperature θ2, the high frequency radio wave is emitted, and if the temperature H or the temperature L is the temperature θ2 or more, the high frequency radio wave is stopped. The high-frequency heating method in which the processing is terminated when both the temperature H and the temperature L become equal to or higher than the temperature θ2. 2. In a high-frequency heating process for heating an object to be heated housed in a heating chamber by applying high-frequency radio waves, the temperature θ of the object to be heated is changed from an initial temperature θ0 to a desired finish temperature θn by high-frequency heating for a heating time τ. The temperature rise characteristic that changes up to is defined by the Newton's cooling formula, and the integrated high frequency irradiation power W (τ) that is irradiated during the heating time τ
Is set in correspondence with the object to be heated, and the temperature rise function Δ (t) = (θ ( t)-
θ 0), the irradiation frequency per unit time is set as the rate of change of the integrated high frequency irradiation power W (t), and the irradiation operation is sequentially performed with the above-mentioned high frequency irradiation power per unit time. The integrated high frequency irradiation power W
A high-frequency heating method in which (τ) is irradiated by allocating time with a temperature rise function Δ (t). 3. The high frequency heating method according to claim 2, wherein the change characteristic of the integrated high frequency irradiation power W (t) is given by the same function as the temperature increasing function Δ (t). 4. The change characteristic of the integrated high frequency irradiation power W (t) is given by a polygonal line approximation of a temperature rise function Δ (t) or an approximation function which arbitrarily combines the polygonal line approximation and the curve approximation. High frequency heating method. 5. The change characteristic of the integrated high-frequency irradiation power W (t) exceeds the temperature rise function Δ (t) in the first half of the heating time τ,
The high frequency heating method according to claim 2 or 4, wherein the latter half is at least lower than the latter half, and is given by an approximate function that coincides at the end of heating. 6. In a high-frequency heating process for heating an object to be heated housed in a heating chamber by applying high-frequency radio waves, the temperature θ of the object to be heated is changed from an initial temperature θ0 to a temperature θi (i) by high-frequency heating for a heating time τ. = 1, 2, ..., N-1), the temperature rise characteristics that change to the desired finish temperature θn are defined by the Newton cooling formula, and the integrated high-frequency irradiation electric energy for irradiation during the heating time τ W (τ) is set corresponding to the object to be heated, and the change characteristic of the integrated high-frequency irradiation power W (t) from the start of heating to the time t is obtained from the temperature increase characteristic, the temperature increase function Δ (t). = (Θ (t) -θ
0), the high frequency irradiation power per unit time in the temperature section from temperature θi to θi + 1 is taken as the rate of change of the integrated high frequency irradiation power W (t) defined in this section, and The temperature of the object is θ j (j = 0, 1, 2, ...,
A high-frequency heating method in which the operation of irradiating with the high-frequency irradiation power amount per unit time is sequentially executed for each temperature section from the time of reaching n-1) until the temperature reaches θj + 1. 7. The high frequency heating method according to claim 6, wherein the change characteristic of the integrated high frequency irradiation power W (t) is given by the same function as the temperature increasing function Δ (t). 8. The change characteristic of the integrated high-frequency irradiation electric power (t) is higher than the temperature rise function Δ (t) at the beginning of the heating time (τ) and lower than Δ (t) at least in the latter half of the heating time (τ) at the end of heating. The high-frequency heating method according to claim 6, wherein the high-frequency heating method is given by an approximate function that matches Δ (t). 9. The method according to claim 6, wherein the change characteristic of the integrated high frequency irradiation power W (t) is given by a function obtained by approximating a temperature rise function by a linear expression in any temperature section. High frequency heating method. 10. The high frequency wave according to claim 6, wherein the change characteristic of the integrated high frequency irradiation power W (t) is given by a function obtained by approximating a temperature rise function in any temperature section by a curve formula. Heating method. 11. The change characteristic of the integrated high frequency irradiation power W (t) is given by a function of an arbitrary combination of a temperature section approximated by a linear expression and a temperature section approximated by a curve expression. The high frequency heating method according to any one of 6 to 8. 12. A high-frequency irradiation for a predetermined short period of time and a subsequent irradiation stop are set as one cycle of heating operation, and the irradiation stop time is set to set a high-frequency irradiation power amount per unit time during one cycle, and the cyclic operation is performed. The high frequency heating method according to any one of claims 6 to 11, wherein high frequency radio waves are radiated by repeating the above. 13. The high frequency heating method according to claim 6, wherein the temperature of the object to be heated is detected by an optical fiber thermometer. 14. The high frequency heating method according to claim 6, wherein the temperature of the object to be heated is detected by measuring the surface temperature. 15. The high frequency wave according to claim 14, wherein the surface temperature of the object to be heated is measured by a temperature sensing element provided inside a plurality of rod-shaped hollow metal bodies forming a mesh of a cage on which the object to be heated is placed. Heating method. 16. The object to be heated is sandwiched and heated by a plate-like oil mat in which edible oil is degassed and sealed in a bag made of a thin plastic film. The high frequency heating method described in. 17. The high frequency heating method according to claim 6, wherein the temperature of the object to be heated is measured between the object to be heated and the oil mat. 18. A Newton's cooling formula and heating time are used to specify the temperature characteristics and heating time when the object to be heated is heated from the initial temperature to the desired temperature by using either a steam oven or a hot water bath. Item 2
18. The high frequency heating method according to any one of 1 to 17. 19. A heating chamber for accommodating an object to be heated, a high-frequency heating source for irradiating the object to be heated with high-frequency radio waves,
A high-frequency heating apparatus comprising: a control unit that controls a high-frequency irradiation operation of the high-frequency heating source, wherein the control unit controls the heat treatment according to any one of claims 1 to 18. 20. The high-frequency heating device according to claim 19, wherein high-frequency heating sources are provided above and below the heating chamber.