JP5124200B2 - High frequency heating device - Google Patents

Description

  The present invention relates to a high-frequency heating device that heats an object to be heated by radiating microwaves into a heating chamber using a rotating antenna.

  A conventional high-frequency heating apparatus of this type includes a waveguide that guides microwaves to a heating chamber, and a control unit that controls a drive motor directly connected to the rotating antenna, and detects information on the microwaves in the waveguide. A microwave detector is installed on the long side of the waveguide, and microwave incident signals and reflected signals are captured at each rotation angle of the rotating antenna. Based on the captured signals, the microwave reflection coefficient Γ or voltage is constant. Obtain the value of the wave ratio ρ, select multiple small values based on the minimum value from these values, stop the rotating antenna at the rotational angle position of the rotating antenna corresponding to the selected value, The thing controlled so that heating efficiency is improved by concentratedly radiating a wave is proposed (for example, refer to patent documents 1).

  In addition, a rotating plate configured in a non-homogeneous shape in the rotational direction is provided from the conductive material, food is placed on the rotating plate, and a different electric field distribution is obtained in the heating chamber by the rotation of the rotating plate. Proposals have been made to stop the rotating plate at a preset stop position according to the input content and the state of the food by the sensor and to heat the food, thereby improving the reduction in the heating efficiency of the food due to uneven heating (for example, patents) Reference 2).

JP 2003-234174 A JP-A-11-193931

  However, in the above prior art, the former one is not as expected because the stop position of the rotating antenna where the reflection coefficient Γ or the voltage standing wave ratio ρ is minimum is not always the maximum output oscillation region of the magnetron. There is a problem that the effect of improving the heating efficiency cannot be obtained.

  In addition, in order to detect a microwave incident signal or reflected signal in a waveguide with a microwave detection device, the microwave detector is installed on the long side portion (H surface) of the waveguide, and the installed waveguide has a certain amount of There is a problem that the transmission loss of the microwave increases when the length is required and the waveguide becomes longer.

  Further, when the microwave detection device is used, there is a problem that the configuration becomes complicated and expensive, and cannot be provided to the user at a low cost.

  Further, when the rotating antenna is stopped, extreme heating unevenness occurs, which causes a problem that the finished state of the food is not good.

  In the latter of the prior art, since the strength of the electric field is generated in the microwave inside the heating chamber, the heating efficiency differs depending on the position where the food is placed on the rotating plate, particularly when heating a relatively small food, There is a large difference in heating efficiency depending on where food is placed. Therefore, even if the rotating plate on which the food is placed is stopped at an appropriate place, there is a problem that the effect is not sufficient depending on the position on which the food is placed.

  Moreover, since extreme heating unevenness occurs when the rotating plate is stopped, there is a problem that the finished state of the food is not good.

  The present invention solves such a conventional problem, and provides a high-frequency heating device excellent in energy saving that improves the heating efficiency of an object to be heated such as food and suppresses the occurrence of uneven heating. is there.

The present invention has been made to solve the above problems, a heating chamber for storing a heated object, a heated object mounting plate for mounting the heated object provided in the heating chamber, A magnetron that oscillates a microwave, a waveguide that attaches the magnetron, a coupling hole that is provided in the bottom of the heating chamber that radiates the microwave guided to the waveguide to the heating chamber, and the coupling hole An antenna post penetrating and provided substantially vertically into the heating chamber and the heating chamber; a rotating antenna provided substantially horizontally at one end of the antenna post below the heated object mounting plate; A drive motor connected to the other end of the antenna post; and a control means for controlling the drive motor, the control means for a predetermined time at the start of heating when the oscillation of the magnetron becomes unstable. Times The controlled not stopped, after the start of heating initial predetermined time is for controlling the drive movement motor so as to stop periodically predetermined time rotation angle set in advance.

In addition, a plurality of weight detecting means configured to support the heated object placing plate are provided, and the weight of the heated object placed on the heated object placing plate detected by the plurality of weight detecting means. The control means controls the rotating antenna to periodically stop for a predetermined time at a preset rotation angle for a period according to information.

In addition, a plurality of weight detecting means configured to support the heated object placing plate are provided, and the weight of the heated object placed on the heated object placing plate detected by the plurality of weight detecting means. When the position information coincides with the preset weight and the position information, the control means controls the rotating antenna to periodically stop for a predetermined time at a preset rotation angle.

The antenna post is connected to the drive motor via a dielectric shaft with a projection, and the projection has the maximum output of the microwave radiated from the magnetron to the object to be heated. The position detector is provided at a position where the position detector is operated when the rotation angle is reached, and the control means stops the rotation of the rotating antenna at the timing when the position detector is operated.
The predetermined time at the beginning of the heating is 12 to 24 seconds.
Further, the preset position information of the object to be heated is the geometric center of the object to be heated mounting plate.

  Since the high-frequency heating device of the present invention is configured as described above, it is possible to improve the heating efficiency of the object to be heated and to further suppress the occurrence of uneven heating.

  In addition, since the rotation antenna is controlled not to stop at the beginning of heating, abnormal heating such as spark between the rotation antenna and the heating chamber wall surface can be prevented, and a highly reliable product can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A first embodiment of a high-frequency heating apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view of a main part of a high-frequency heating device showing a first embodiment of the present invention, FIG. 2 is a perspective view of the same high-frequency heating device, and FIG. 4 is a perspective view of a driving motor provided in the lower part of the waveguide, and FIG. 5 is a timing chart showing a method for controlling the rotating antenna.

  In the figure, the high-frequency heating device is provided with a heating chamber 2 made of a metal thin plate that accommodates an object to be heated 1 such as food to be cooked. In front of the heating chamber 2, an openable / closable door 3 for taking in and out the article 1 to be heated is provided. A heated object placing plate 4 made of a material having a low dielectric loss for placing the heated object 1 is elastically supported by a seal member (not shown) on the lower part of the heating chamber 2. The heated object 1 such as food is placed. This configuration is a so-called turntableless type.

  A machine chamber 16 is provided between the heating chamber 2 and the bottom surface of the high-frequency heating apparatus main body, and is separated from the heating chamber 2 by a thin plate constituting the casing of the heating chamber 2 so as to cut off heat or microwaves. Yes.

  The machine room 16 includes a magnetron 7 that generates a microwave necessary for heating the article 1 to be heated, an inverter power source 8 that controls a microwave output by oscillation of the magnetron 7, a control unit 9 that controls the inverter power source 8, and the like. It has.

  Weight detection means 5 a, 5 b, 5 c configured to support the object to be heated placing plate 4 are provided at two places on the front left and right corners of the to-be-heated object placing plate 4 and one end of the rear center. ing. Information on the weight detected by the respective weight detection means 5a, 5b, 5c is input to the control means 9, and the information on the weight detected by the weight detection means 5a, 5b, 5c is summed to place the object to be heated. The weight of the object to be heated 1 placed on the plate 4 can be detected. Further, the position of the object to be heated 1 in the left-right direction (X direction) and the depth direction (Y direction) of the heating chamber 2 is detected by the control means 9 based on the weight information of the respective weight detection means 5a, 5b, 5c. .

  The weight detectors 5a, 5b, and 5c are static detectors that detect a change in the distance due to the displacement or deformation of a part of the structure based on the weight of the heated object 1 placed on the heated object placing plate 4. Capacitance type weight detection means or optical type optical displacement type weight detection means may be used. Further, a strain gauge type weight detection means such as a strain gauge for detecting stress or strain generated in a part of the structure due to the weight of the object to be heated 1 may be used.

  Microwaves generated from the magnetron 7 are radiated to the space 2 a provided between the heating object mounting plate 4 and the coupling hole 13 provided in the substantially central portion of the bottom surface of the heating chamber 2 through the waveguide 6. Then, it is radiated into the heating chamber 2 through the heated object placing plate 4.

  The coupling hole 13 to which the microwave is supplied is provided with a waveguide 6 passing through the coupling hole 13 and an antenna post 14 provided substantially vertically in the space 2a.

  At the end of the antenna post 14 on the space 2a side, a metal flat plate rotating antenna 10 fixed substantially horizontally is provided.

  A drive motor 11 is connected to the end of the antenna post 14 outside the waveguide 6 via a dielectric shaft 12 with protrusions 12a. Then, the rotating antenna 10 is rotated by the operation of the drive motor 11, and the microwave is agitated and radiated to the heated object 1 placed on the heated object mounting plate 4.

  When the rotary antenna 10 is rotationally driven by the drive motor 11, the microswitch of the position detector 15 constituted by the microswitch is turned on and off by the protrusion 12 a of the dielectric shaft 12, and the generated signal is input to the control means 9. Thus, the rotation angle of the rotating antenna 10 can be detected.

  The microwave output radiated into the heating chamber 2 by the rotating antenna 10 has an oscillation region in which the microwave output radiated by the magnetron 7 is maximum depending on the rotation angle of the rotating antenna 10. Accordingly, the projection 12a of the dielectric shaft 12 is obtained so that a signal can be obtained from the position detector 15 when the rotation angle of the rotary antenna 10 at which the output of the microwave radiated from the magnetron 7 becomes the maximum with respect to the object 1 to be heated. The control means 9 controls the drive motor 11 at the timing when the detection signal from the position detector 15 is detected, stops the rotating antenna 10, and radiates microwaves to the object 1 to be heated. As a result, the object to be heated 1 is heated in the oscillation region where the microwave output from the magnetron 7 is maximized, so that the heating efficiency of the object to be heated 1 can be increased.

  The operation of the high-frequency heating apparatus configured as described above will be described with reference to FIG. The user opens the door 3 of the high-frequency heating device and places the article 1 to be heated on the article-to-be-heated plate 4, then closes the door 3 and sets the heating time of the article 1 to be operated (not shown). When the operation of starting the heating of the high-frequency heating device is performed, the weight of the heated object 1 is first detected by the weight detection means 5a, 5b, 5c, and the detected weight information of the heated object 1 is displayed. Accordingly, the control means 9 calculates and calculates the rotating antenna control time T4 shown in FIG.

  Next, the control means 9 controls the inverter power supply 8 to operate the magnetron 7 to generate microwaves. The generated microwave is supplied to the heating chamber 2 from the coupling hole 13 through the waveguide 6. At this time, the control means 9 controls the drive motor 11 to rotate the rotating antenna 10 so as to diffuse the microwaves into the heating chamber 2 and uniformly heat it, and to stop the rotating antenna 10 and to heat the object 1 to be heated. Control to heat efficiently.

  For example, the case where the article to be heated 1 is water and the weight is about 300 ml will be described with reference to FIG. The control means 9 drives the rotating antenna 10 without stopping for 12 to 24 seconds (T1) during a period in which two pulses of the rotating antenna position detection signal from the position detector 15 are generated. Thereafter, the drive motor 11 is controlled at the signal detection timing of the position detector 15 to stop the rotating antenna 10 for 12 seconds (T2). Thereafter, the drive motor 11 is again controlled to rotate the rotating antenna 10 for 12 seconds (T3) until the next position detector 15 signal is received, and again at the signal detection timing of the position detector 15 for 12 seconds (T2). ) The rotating antenna 10 is stopped. This operation is repeatedly executed, and the stop control operation of the rotating antenna 10 is terminated 140 seconds (T4) after the start of heating. Thereafter, the stop control of the rotating antenna 10 is performed until the heating time T5 set for the first time has elapsed. Without rotation, the rotating antenna 10 is always rotated, and the energization of the magnetron 7 is stopped after the first input heating time T5 has elapsed.

  Note that the drive motor 11 used here has a value of T3 of 12 seconds because the time required to rotate the rotary antenna 10 once is 12 seconds. The speed at which the rotating antenna 10 is rotated once in 12 seconds is a value suitable for diffusing the supplied microwave to minimize the uneven heating of the article 1 to be heated. The effect of improving unevenness is reduced.

  The rotating antenna 10 is not stopped for 12 to 24 seconds (T1) during the period in which two pulses of the rotating antenna position detection signal from the position detector 15 at the beginning of heating are generated. Since the oscillation of the magnetron 7 becomes unstable at the beginning of energization, if the rotating antenna 10 is stopped during this period, abnormal heating due to sparks between the rotating antenna 10 and the wall surface of the heating chamber 2 may occur. In order to prevent this, the control for stopping the rotating antenna 10 is not performed until the oscillation of the magnetron 7 is stabilized. Thereby, it can be set as a highly reliable product.

  Further, the control to stop the rotating antenna 10 after 140 seconds (T4) from the start of heating is performed when the heating temperature of the object to be heated 1 rises to 70 to 80 ° C. Since the loss factor that is a measure for generating heat by absorbing wave energy is reduced to about 1/4 to 1/5 at room temperature, it becomes difficult to heat even if the rotary antenna 10 is stopped and controlled, as in the present invention. The heating time until the temperature rises to 70 to 80 ° C. when microwave heating is performed is estimated from the weight of the heated object 1. For example, when the heated object 1 is water and the weight is approximately 300 ml, the rotating antenna The control time T4 is determined to be 140 seconds for control. As a result, the object to be heated 1 is heated with high heating efficiency in a short time to be excellent in energy saving, and the rotation antenna 10 is not stopped after the time T4 so as to suppress the occurrence of uneven heating. Thus, the object to be heated 1 can be finished in a good heating state.

  As described above, the rotating antenna 10 is stopped at the position of the oscillation region where the output of the magnetron 7 is maximized, and the heating of the object 1 to be heated is increased with the microwave heating efficiency. By rotating and suppressing the occurrence of uneven heating and repeating the control to stop the rotating antenna 10 for a predetermined time again, the operating time in the maximum output oscillation region of the magnetron 7 is increased and the heating efficiency is increased The occurrence of uneven heating that occurs when the antenna 10 is stopped can be suppressed.

  Further, the rotating antenna 10 is periodically rotated at a preset rotation angle for a period corresponding to the weight information of the object 1 to be heated placed on the object-to-be-heated object placement plate 4 detected by the weight detection means 5a, 5b, 5c. In order to further suppress the occurrence of heating unevenness by controlling the control means 9 so as to stop for a predetermined time, and then preventing the rotation antenna 10 from being stopped and thereby suppressing the occurrence of heating unevenness. The article to be heated 1 can be finished in a good heating state.

  In addition, although the oscillation of the magnetron 7 becomes unstable at the beginning of heating, control is performed so that the rotating antenna 10 is not stopped during this period, so that abnormal heating such as sparking between the rotating antenna 10 and the wall surface of the heating chamber 2 is prevented. Therefore, it can be made a highly reliable product.

  Further, since the microwave detection device is not used, the length of the waveguide 6 can be shortened, and an increase in transmission loss of microwaves can be suppressed, so that the heating efficiency can be increased.

  Furthermore, the object to be heated 1 can be efficiently heated with a simple and inexpensive configuration without using a complicated microwave detection device.

  Next, a second embodiment of the high-frequency heating device according to the present invention will be described with reference to FIG. The description of the same part as in the first embodiment is omitted.

  FIG. 6 is a flowchart showing the control operation of the rotating antenna according to the second embodiment of the present invention. The second embodiment is different from the first embodiment in that the weight of the object to be heated 1 and the object to be heated placed on the object to be heated platen 4 are determined by the weight information of the weight detection means 5a, 5b, 5c. The position of the object 1 is obtained by the control means 9, and the stop control of the rotating antenna 10 is performed based on the weight and position information, and other configurations are the same as those in the first embodiment.

  Next, the operation will be described with reference to FIG. When the object to be heated 1 is placed on the object to be heated placing plate 4 in the heating chamber 2 and heating is started in step 601, the object to be heated is detected in step 602 from the weight information detected by the weight detecting means 5a, 5b, 5c. The weight of the article 1 and the placement position of the article to be heated 1 placed on the article to be heated placing plate 4 are detected, and whether or not the weight and the placement position match the preset weight and the placement position. In step 603, the determination is made. For example, the preset placement position of the heated object 1 is the geometric center of the heated object placing plate 4, and the weight of the heated object 1 is a weight that is a small load of liquid such as milk or liquor. .

  Next, if the weight and the mounting position match at step 603, control is performed to stop the rotating antenna 10 at a specific rotation angle for a predetermined time at step 604. If they do not coincide with each other at step 603, control is performed to always rotate without performing control to stop the rotating antenna 10 at step 606, and heating is performed until the end of the heating time at step 605.

  Such a control is performed as shown in FIG. 5, and for the small object 1 to be heated, the rotating antenna 10 is stopped at the position of the oscillation region where the output of the magnetron 7 is maximum, and the object 1 is heated. The microwave is heated to increase the heating efficiency, and after a predetermined time, the rotating antenna 10 is rotated to suppress the occurrence of uneven heating, and the control for stopping the rotating antenna 10 again for a predetermined time is repeated. To do. By performing such control, the heating time is increased while increasing the operation time in the maximum output oscillation region of the magnetron 7 to increase the heating efficiency, while suppressing the occurrence of heating unevenness caused by the stop of the rotating antenna 10 as much as possible. Can be shortened to save energy.

  And for the heated object 1 that is large and heavy, in order to prevent the heating finish from being deteriorated due to uneven heating, the finish with little uneven heating is performed without controlling the rotating antenna 10 to stop. Can do good cooking.

  Further, when heating a plurality of small objects to be heated 1 at a time, the center of gravity position of the entire object to be heated 1 is set in the heating chamber so that the finished temperature does not vary due to uneven heating. If it arrange | positions so that it may not become the geometrical center of 2, since control which always rotates without performing the control which stops the rotating antenna 10 is performed, generation | occurrence | production of a heating nonuniformity can be reduced and it can cook well.

  The reason why the preset placement position of the heated object 1 is the geometric center of the heated object placing plate 4 is that the microwave generated from the magnetron 7 is transmitted through the waveguide 6 through the bottom surface of the heating chamber 2. Of the rotating antenna 10 having a heating pattern in which the geometrical central portion of the object-to-be-heated object placing plate 4 is strongly heated by radiating into the heating chamber 2 from the coupling hole 13 provided at the center of the rotating antenna 10. This is because the shape can be set relatively easily.

  As described above, when the small article to be heated 1 is placed at the geometric center of the article to be heated 4, it is automatically determined that the small article to be heated 1 is taken into consideration, and heating unevenness is not taken into consideration. Energy saving and convenience can be improved by stopping heating at the rotation angle of the rotating antenna 10 that heats the center load most efficiently with emphasis on heating efficiency and heating efficiently to shorten the heating time.

  Further, for the heated object 1 in which the heating unevenness in which the large object to be heated 1 and the place to place the heated object 1 are not placed at the geometric center of the heated object mounting plate 4 is not preferable, the control means Therefore, the rotating antenna 10 is not automatically stopped and the cooking is performed with little unevenness of heating, and the usability can be improved.

It is a principal part longitudinal cross-sectional view of the high frequency heating apparatus which shows the 1st Example of this invention. It is a perspective view of a high frequency heating device. It is a perspective view explaining the structure of a rotation antenna similarly. It is a perspective view of the drive motor similarly provided in the lower part of the waveguide. It is a timing chart which similarly shows the control method of a rotating antenna. It is a flowchart which shows the control operation of the rotating antenna which shows the 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heated object 2 Heating chamber 4 Heated object mounting board 5 Weight detection means 6 Waveguide 7 Magnetron 9 Control means 10 Rotating antenna 11 Drive motor 13 Coupling hole 14 Antenna post

Claims (6)

A heating chamber for storing an object to be heated, a heating object mounting plate for mounting the object to be heated provided in the heating chamber, a magnetron for oscillating microwaves, and a waveguide for mounting the magnetron; A coupling hole provided in the bottom surface of the heating chamber that radiates microwaves guided to the waveguide to the heating chamber, and passes through the coupling hole and faces the waveguide and the heating chamber substantially vertically. An antenna post provided; a rotating antenna provided substantially horizontally at one end of the antenna post below the object mounting plate; a drive motor connected to the other end of the antenna post; and the drive motor Control means for controlling
The control means includes
Control so as not to stop the rotation of the rotating antenna for a predetermined time at the beginning of heating when the oscillation of the magnetron becomes unstable,
Wherein after heating start initial predetermined time high-frequency heating apparatus characterized by controlling the drive movement motor so as to periodically be stopped for a predetermined time at a rotation angle that is set in advance. According to claim 1, wherein a plurality of weight detecting means arranged to support the object to be heated mounting plate provided, heated placed on mounting plate the object to be heated detected by the plurality of weight detecting means A high-frequency heating apparatus controlled by the control means so as to periodically stop the rotating antenna at a predetermined rotation angle for a predetermined period of time according to the weight information of an object. According to claim 1, wherein a plurality of weight detecting means arranged to support the object to be heated mounting plate provided, heated placed on mounting plate the object to be heated detected by the plurality of weight detecting means When the weight and position information of the object coincides with the preset weight and position information, the control means controls the rotating antenna to periodically stop for a predetermined time at a preset rotation angle. High frequency heating device. In claim 1 or claim 2,
The antenna post is connected to the drive motor via a dielectric shaft with a protrusion,
The protrusion is provided at a position to operate a position detector when the rotation angle of the rotating antenna reaches a maximum output of the microwave radiated from the magnetron to the object to be heated.
The high frequency heating apparatus, wherein the control means stops the rotation of the rotating antenna at a timing when the position detector is operated. In claim 1,
The high frequency heating apparatus according to claim 1, wherein the predetermined time at the beginning of the heating is 12 to 24 seconds. In any one of Claims 1-5,
The high-frequency heating apparatus according to claim 1, wherein the preset position information of the heated object is a geometric center of the heated object mounting plate.

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