JP2011144942A - High-frequency heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-frequency heating device capable of efficiently heating a heated object. <P>SOLUTION: This high-frequency heating device includes a weight detecting means 5 for measuring a weight of the heated object 20, a rotary antenna 10 disposed on an upper end section of an antenna post 14, a driving motor 11 connected to a lower end section of the antenna post 14 through a dielectric shaft 12 having a projection 12a in the circumferential direction, a position detector 15 for detecting a position of the projection 12a, and a control means 9 for controlling the driving motor 11 on the basis of the information from the weight detecting means 5 and the position detector 15. In heating the heated object 20, the control means 9 allows the rotary antenna 10 to make a 360-degree turn first, then manages a stop position of the rotary antenna 10 based on a lapse time from the detection information of the position detector 15 according to the weight information of the weight detecting means 5, repeats rotation and stop several times during the 360-degree turn of the rotary antenna 10, and allows the rotary antenna 10 to continuously rotate until the heating is terminated, after the lapse of time when a temperature of the heated object 20 reaches 80% of a heating termination temperature. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  In this type of conventional high-frequency heating device, the magnetron oscillation is unstable immediately after the start of heating and the microwave output is small, and the microwave output is large 12 to 24 seconds after the rotating antenna makes one to two turns. Become stable.

  In order to cope with this, heating is performed without stopping the rotating antenna immediately after the start of heating, and heating is performed in an oscillation region in which the microwave output from the magnetron is maximized after 12 to 24 seconds after the rotating antenna makes one to two turns. In some cases, the rotating antenna is stopped at a specific position every round so that heating can be performed without stopping the rotating antenna so as to suppress the occurrence of heating unevenness (for example, Patent Document 1).

JP 2009-36449 A

  However, in the above prior art, especially when the weight of the food is small, when heating is performed while stopping in the oscillation region where the output of the microwave radiated from the magnetron is maximum, the local heating increases, and then uneven heating is caused. There is a problem that uneven heating remains even if heating is performed without stopping the rotating antenna so as to suppress generation.

  In addition, the stop position of the rotating antenna that maximizes the output of the microwave differs depending on the weight of the food, and there is a problem that the finished temperature after heating becomes low depending on the weight of the food.

  Furthermore, since the stop position of the rotating antenna after the heating is different depending on the heating time required for heating, there is a problem that it takes time to detect the rotating position of the rotating antenna at the start of heating.

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

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In claim 1, a heating chamber for storing an object to be heated, a door for opening and closing the heating chamber, and a door switch for detecting opening and closing of the door. And a heated object placing plate that is provided at the bottom of the heating chamber and places the heated object, and a weight detecting unit that supports the heated object placing plate and measures the weight of the heated object, A magnetron for radiating microwaves, a waveguide connected to the magnetron, a coupling hole provided in a bottom plate of the heating chamber for radiating microwaves from the waveguide to the heating chamber, and the coupling An antenna post provided so as to pass through a hole and face the waveguide and the heating chamber substantially vertically, and provided substantially horizontally at an upper end portion of the antenna post below the object mounting plate. Rotating antenna and circumference at the lower end of the antenna post A drive motor connected via a dielectric shaft provided with a protrusion, a position detector for detecting the position of the protrusion rotated by the drive motor, information on the weight detection means and the position detector Control means for controlling the drive motor,
When heating the object to be heated, the control unit first rotates the rotating antenna once, and then determines the stop position of the rotating antenna according to the weight information of the weight detecting unit. After the time when the temperature of the object to be heated reaches 80% of the heating end temperature, the heating is completed until the heating ends. The rotating antenna is continuously rotated.

  According to a second aspect of the present invention, the control means can detect the protrusion of the position detector when the opening of the door is detected by the information of the door switch when the object to be heated is not heated. The drive motor is driven to rotate the rotating antenna, and the drive motor is stopped when the position detector detects the position of the protrusion.

  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 heating unevenness.

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 in the state where a part of a high-frequency heating device was cut similarly. It is a perspective view explaining the structure of a rotation antenna similarly. It is the perspective view which looked at the drive motor part similarly provided in the lower part of the waveguide from the bottom. It is a timing chart which similarly shows the control method of a rotating antenna.

  Hereinafter, an embodiment of a high-frequency heating device according to the present invention will be described with reference to FIGS.

  In the figure, a heating chamber 2 is provided in the main body 1 of the high-frequency heating device.

  A door 3 that can be opened and closed is provided in front of the heating chamber 2 so that the object to be heated 20 can be taken in and out. When the door 3 is closed, the flange portion 18 provided in the heating chamber 2 and the door 3 are in close contact with each other. The heating chamber 2 is sealed.

  A convex portion 3 a is provided on the inner peripheral surface of the door 3, and the convex portion 3 a protrudes from a hole 18 a provided in the flange portion 18 when the door 3 is closed and is provided on the outside of the heating chamber 2. ON / OFF state of the door is detected.

  On the bottom plate 2b of the heating chamber 2, a heated object placing plate 4 made of a material having a small dielectric loss is supported by weight detecting means 5 described later, and the heated object 20 is placed on the upper surface thereof. Yes.

  The weight detection means 5 is provided at two places (5a, 5b) at the front left and right corners of the heated object placing plate 4 and at one place (5c) at the rear center, and supports the heated object placing plate 4. 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 20 placed on the plate 4 can be detected.

  A machine chamber 16 is provided between the bottom surface of the main body 1 and the heating chamber 2, 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. .

  The machine room 16 includes a magnetron 7 that radiates microwaves necessary for heating the article 20 to be heated, an inverter power supply 8 that controls the microwave output generated by the magnetron 7 oscillating, and a control unit 9 that controls the inverter power supply 8. It has.

  Microwaves radiated from the magnetron 7 pass through the waveguide 6 connected to the magnetron 7, and are coupled to the bottom plate 2 b of the heating chamber 2 from the coupling hole 13 provided in the substantially central portion of the bottom plate 2 b of the heating chamber 2. It is radiated into the space 2 a provided between the heated object placing plate 4 and further radiated into the heating chamber 2 through the heated object placing plate 4.

  In the coupling hole 13 to which the microwave is supplied, an antenna post 14 is provided so as to pass through the coupling hole 13 and face the waveguide 6 and the space 2a substantially vertically.

  A rotating antenna 10 made of a metal flat plate is provided substantially horizontally at the upper end portion of the antenna post 14 so as to be positioned in the space 2a, and the drive motor 11 is provided at the lower end portion via a dielectric shaft 12 with a protrusion 12a. Is connected. The rotating antenna 10 is rotated by driving the drive motor 11.

  A synchronous motor is used as the drive motor 11, and the rotation speed is determined by the applied frequency. The drive motor 11 used here is a motor provided with a speed reducer. When the frequency of the power supply to be applied is 50 Hz, the time required for one rotation of the output shaft is 12 seconds, and when the frequency is 60 Hz. 10 seconds. In addition, a mechanism that always rotates in a certain direction is provided.

  When the rotary antenna 10 is rotated by driving the drive motor 11, the micro switch of the position detector 15 constituted by the micro switch is turned on and off by the protrusion 12a of the dielectric shaft 12, and the generated rotary antenna position detection signal is generated. The position of the rotating antenna 10 rotating can be detected by inputting to the control means 9.

  The control means 9 can confirm that the rotating antenna 10 is rotating by confirming the rotating antenna position detection signal which is a signal from the position detector 15.

  For example, when the frequency of the power source applied to the drive motor 11 is 50 Hz, the time required for one rotation of the protrusion 12a is 12 seconds, so the microswitch of the position detector 15 is also turned on once every 12 seconds. When the frequency of the power supply is 60 Hz, since the time required for one rotation of the output shaft is 10 seconds, the microswitch of the position detector 15 is also turned ON once every 10 seconds.

  For this reason, it is possible to confirm that the rotating antenna 26 is rotating normally by measuring the time during which the microswitch of the position detector 15 is turned ON and turned OFF and then turned ON again.

  In addition, it is possible to specify the position where the rotating antenna 10 is rotating in the elapsed time after the microswitch of the position detector 15 is turned on. Therefore, the control means 9 is provided with means for detecting the frequency of the applied power supply before the start of heating.

  The rotating antenna 10 is rotated by the drive motor 11 and radiates microwave energy uniformly to the heated object 20 placed on the heated object mounting plate 4. When the rotation stops, the microwave energy received by the food becomes unbalanced and heating unevenness occurs. However, depending on the angle at which the rotating antenna 10 stops, there is an oscillation region where the output of the microwave radiated by the magnetron 7 is maximized, and the rotating antenna 10 is intentionally stopped and the characteristic of heating imbalance is utilized. Heating efficiency can be increased.

  The shape of the rotating antenna 10 and the number and shape of the rotating holes 10a are adjusted according to the size of the heating chamber 2 and the like.

  The operation of the high-frequency heating apparatus configured as described above will be described with reference to FIG.

  FIG. 5 shows the heating time on the horizontal axis, the rotating antenna drive signal output from the control means 9 for operating the drive motor 11 on the vertical axis, and the control means 9 as the rotary antenna 10 rotates. It is the figure which showed the state of the rotation antenna position detection signal which is a signal from the position detector.

  After the user opens the door 3 of the high-frequency heating device and places the article to be heated 20 on the article to be heated placing plate 4, the user closes the door 3 and heats the article to be heated 20 (not shown). To start heating of the high-frequency heating device.

  When heating is started, the control means 9 first detects the weight of the object to be heated 20 by the weight detection means 5a, 5b, 5c, and according to the detected weight information of the object to be heated 20, the heating time T shown in FIG. And calculating the rotation antenna control time T1.

  The rotating antenna 10 being heated rotates the rotating antenna 10 while rotating and stopping from the second rotation after rotating the rotating antenna 10 for the first time during the rotating antenna control time T1, and then the heating time T ends. The rotating antenna 10 is continuously rotated so as to uniformly heat the object 20 to be heated.

  The reason why the rotating antenna 10 is rotated once without stopping at the beginning of heating is to stabilize the state of the magnetron 7 and the object to be heated 20.

  The magnetron 7 is composed of a cathode (also used as a heater) and an anode (not shown) as an electrical configuration. An electric current is supplied to the heater to cause the heater to generate heat. When the heater is warmed, an anode current starts to flow between the cathode and the anode. When the anode current flows to the rated value, the magnetron 7 becomes stable. Therefore, the rotating antenna 10 is heated without being stopped until the stable state is reached.

  In addition, when the object to be heated 20 is a liquid such as miso soup, for example, the impedance of the heating chamber 2 is disturbed by the wave of the liquid level generated when the object to be heated 20 is placed on the object to be heated placing plate 4. This is because the position where the rotating antenna 10 stops so that the microwave is efficiently absorbed by the object to be heated 20 is shifted, so that the rotating antenna 10 is heated without stopping until the wave generated on the liquid surface disappears. I have to.

  Next, as for the position where the rotating antenna 10 is stopped, it is preferable to stop at a position where the microwave oscillated by the magnetron 7 is most efficiently absorbed by the object to be heated, but it is stopped at one place for a long time and heated. Then, since heating unevenness occurs, the rotating antenna 10 is repeatedly heated and stopped repeatedly at the second, third, and the portions where the microwave absorption efficiency is good.

  And the stop location is determined by the elapsed time after the microswitch of the position detector 15 is turned on, and the time required for one rotation of the rotating antenna differs depending on the frequency of the power source used, so it corresponds to the frequency used. Elapsed times ta and tc are determined (in FIG. 5, when the power source used is 50 Hz, control is performed at the upper stage, and when it is 60 Hz, control is performed at the lower stage).

  Further, the time for which the rotating antenna 10 is stopped is also determined according to the weight of the article to be heated 20 to such an extent that heating unevenness does not occur after heating.

  As described above, the rotating antenna 10 determines the position to stop and the stop time according to the weight of the object to be heated 20, and the relationship is determined by subdividing the weight of the object to be heated 20. It may be determined within a certain weight range.

  Here, the weight, the stop position of the rotating antenna 10, and the stop time will be described assuming that the most frequently used rice is warmed.

  For example, if the rotation control of the rotating antenna 10 is managed in three stages of one cup of rice (including the weight of 300 g teacup), two cups (including the weight of 600 g teacup), three cups (including the weight of 900 g teacup), The weight can be divided into 450 g or less, two cups of 451 g to 750 g, and three cups or more of 751 g or more.

  The control means 9 has a relationship between the stop position of the rotating antenna 10 having a weight of 450 g or less, 451 to 750 g, 751 g or more and good absorption efficiency of the microwave radiated by the magnetron 7 and the stop time in which the heating unevenness can be minimized. Confirm in advance and store as data.

  The heating is performed as a control time T1 of the rotating antenna until it reaches about 80% of the final heating temperature of the article 20 to be heated. Then, during the remaining heating time, the heating is performed without stopping the rotating antenna 10 so as to prevent the local heating from progressing and to uniformly heat the object to be heated.

  In addition, when the weight of the object to be heated 20 is increased, the difference in microwave absorption efficiency depending on the stop position of the rotating antenna 10 is reduced. Therefore, in this embodiment, when the amount of three or more servings of rice is warmed, the rotating antenna 10 Not to stop.

  Next, the position of the rotating antenna of the position detector 15 is opened when the door 3 for opening / closing the object to be heated 20 is opened / closed so that the rotation starting position of the rotating antenna 10 always coincides when heating starts. The state of the detection signal is detected, the rotating antenna 10 is rotated by the drive motor 11 to the position where the micro switch of the position detector 15 is turned on, and the rotating antenna 10 is always stopped at the position where the micro switch of the position detector 15 is turned on. So that it is controlled.

  By doing so, since the position of the rotating antenna 10 is always rotated from the position where the micro switch of the position detector 15 is turned on at the start of heating, the position of the rotating antenna 10 can be confirmed immediately after the start of heating. In order to detect the position, time for rotating the rotating antenna 10 unnecessarily becomes unnecessary.

  Therefore, it becomes possible to efficiently heat the article 20 to be heated in a limited heating time T.

  The object to be heated 20 is heated by controlling the inverter power supply 8 by the control means 9 to oscillate the magnetron 7 and emit microwaves. The radiated microwave is supplied to the heating chamber 2 from the coupling hole 13 through the waveguide 6.

  Immediately after the start of heating, the rotating antenna 10 makes one rotation without stopping, and then enters the rotating antenna control for stopping the rotating antenna from the second rotation.

  And the measurement of the elapsed time ta for stopping the rotation antenna 10 is started on the basis of the signal that the micro switch of the position detector 15 is turned on when the rotation antenna 10 enters two rotations.

  For example, the case where the frequency of the power source to be used is 50 Hz and the heated object 20 to be heated is rice full of teacups will be described with reference to FIG.

  Based on the information from the weight detection means 5, the control means 9 determines that the weight of the article to be heated 20 is 450 g or less, and performs control in that case.

  The heating time T is 40 seconds, the rotating antenna control time T1 is 32 seconds, the time t0 required for one rotation of the rotating antenna is 12 seconds, the number of times that the rotating antenna stops once is twice, and the stop position (position The elapsed time from when the microswitch of the detector 15 is turned on) ta is 5 seconds, tc 3 seconds, the stop time tb is 2 seconds, td 4 seconds.

  When the ON signal is input from the micro switch of the position detector 15 of the second rotation after the control means 9 first rotates the rotating antenna 10 once (12 seconds), the rotating antenna 10 is input from the input of the ON signal. Start time measurement for rotation control.

  Then, the rotating antenna 10 enters the second rotation, rotates for 5 seconds (ta) after the ON signal from the micro switch of the position detector 15 is input, and then stops for 2 seconds (tb). 10 is rotated for 3 seconds (tc), then stopped for 4 seconds (td), and then the rotating antenna 10 is further rotated. Four seconds after the start of rotation, the rotating antenna 10 enters the third rotation.

  Simultaneously with the rotation of the rotating antenna 10 entering the third rotation, the ON signal from the micro switch of the position detector 15 is input again. Thereafter, the rotation antenna control time T1 of 32 seconds has elapsed since the start of heating, and the heating is continued without stopping the rotation antenna 10 for the remaining heating time, and the heating is terminated when the heating time T of 40 seconds has elapsed.

  After the heating is finished, when the door 3 is opened to take out the article 20 to be heated from the heating chamber 2, a signal from the door switch 17 that detects opening / closing of the door 3 is detected, and the stop position of the rotating antenna 10 is determined. The state of the micro switch of the position detector 15 shown is detected, and the rotation antenna 10 is rotated until an ON signal is obtained from the micro switch, and then the rotation is stopped.

  As described above, according to the present invention, it is possible to improve the heating efficiency of the object to be heated, and to suppress the occurrence of uneven heating.

DESCRIPTION OF SYMBOLS 1 Main body 2 Heating chamber 4 Heated object mounting plate 5 Weight detection means 6 Waveguide 7 Magnetron 9 Control means 10 Rotating antenna 11 Drive motor 14 Antenna post 15 Position detector 17 Door switch

Claims (2)

A heating chamber for storing an object to be heated, a door for opening and closing the heating chamber, a door switch for detecting opening and closing of the door, and an object mounting for mounting the object to be heated provided at the bottom of the heating chamber A placing plate, a weight detecting means for supporting the heated object placing plate and measuring the weight of the heated object, a magnetron for emitting microwaves, a waveguide connected to the magnetron, and the heating chamber A coupling hole for radiating a microwave from the waveguide to the heating chamber, and a hole penetrating the coupling hole and facing the waveguide and the heating chamber. An antenna post, a rotating antenna provided substantially horizontally at the upper end of the antenna post below the object mounting plate, and a dielectric shaft provided with a protrusion in the circumferential direction at the lower end of the antenna post A drive motor connected via the motor, and the drive motor Therefore comprising a position detector for detecting a position of said projection for rotating, and a control means for controlling said drive motor based on information of the position detector, the weight detecting means,
When heating the object to be heated, the control unit first rotates the rotating antenna once, and then determines the stop position of the rotating antenna according to the weight information of the weight detecting unit. After the time when the temperature of the object to be heated reaches 80% of the heating end temperature, the heating is completed until the heating ends. A high-frequency heating apparatus, wherein the rotating antenna is continuously rotated.   2. The control device according to claim 1, wherein the control means can detect the protrusion of the position detector when the opening of the door is detected based on information of the door switch when the object to be heated is not heated. The high-frequency heating apparatus is characterized in that the drive motor is driven to rotate the rotating antenna, and the drive motor is stopped when the position detector detects the position of the protrusion.

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