JP5482496B2 - High frequency heating device - Google Patents

Description

  The present invention relates to a high-frequency heating apparatus that determines the state of an object to be heated at the start of heating and performs heating according to the state of the object to be heated.

  Conventionally, this type of high-frequency heating device detects a component in the direction of reflection of high-frequency power transmitted through a waveguide, and controls the driving of the magnetron when a predetermined change occurs in the detection signal of the reflected power component (For example, refer to Patent Document 1).

JP-A-4-245190

  However, since the configuration of Patent Document 1 controls the driving of the magnetron by utilizing the change in the dielectric properties of the food due to the temperature change accompanying the progress of heating, for example, it can be determined whether the frozen state is at a significantly different dielectric property or normal temperature. However, it cannot be determined whether the object to be heated is liquid or solid. Therefore, it is difficult to perform heating according to the state of the object to be heated.

  This invention solves the said conventional subject, and it aims at providing the high frequency heating apparatus which determines the state of a to-be-heated object at the time of a heating start, and enables the heating according to the state of a to-be-heated object. .

In order to solve the above-described conventional problems, a high-frequency heating device of the present invention includes a heating chamber that houses an object to be heated, a microwave generation unit that generates a microwave, and a high-frequency power source that drives the microwave generation unit. A microwave transmission means for coupling the heating chamber and the microwave generation means, a reflected power detection means for detecting the microwave power provided in the microwave transmission means and reflected from the heating chamber to the microwave generation means, In the high-frequency heating apparatus having a control unit that controls the high-frequency power source based on a detection signal of the reflected power detection unit, the control unit operates the high-frequency power source at the start of heating and applies a microwave to the heating chamber. radiation and, on the basis of the heating chamber to the behavior of the detection signal of the reflected power detecting means for detecting the microwave power to be reflected to the microwave generation means and the State of the heated object is to determine whether liquid or solid.

  Thereby, since heating according to the state of a to-be-heated object can be performed, overheating of a to-be-heated object can be prevented.

  Further, the control means of the present invention determines that the object to be heated is a liquid when the detection signal of the reflected power detection means has an amplitude greater than or equal to a predetermined value at the start of heating. As a result, bumping or the like due to overheating of the object to be heated can be prevented, and safety can be improved.

  The control means of the present invention determines that the object to be heated is solid when the detection signal of the reflected power detection means has an amplitude less than a predetermined value at the start of heating. Thereby, since heating according to the state of a to-be-heated object can be performed, overheating of a to-be-heated object can be prevented.

  In addition, when the control means of the present invention determines that the object to be heated is a liquid, the control means controls the high-frequency power supply so that microwaves are generated at a high output in the initial stage of heating, and the microwaves are generated after a predetermined time has elapsed. The high-frequency power supply is controlled so as to reduce the output. Accordingly, overheating of the heated object can be prevented, and the heated object after the heating can be finished with high quality.

  Since the high-frequency heating device of the present invention can perform heating according to the state of the object to be heated, overheating of the object to be heated can be prevented.

Schematic configuration diagram of a high-frequency heating device in an embodiment of the present invention The figure which shows the operation | movement outline | summary of the high frequency heating apparatus in embodiment of this invention. The elements on larger scale which show the operation | movement outline | summary of the high frequency heating apparatus in embodiment of this invention

1st invention couple | bonds the heating chamber which accommodates to-be-heated material, the microwave generation means which generate | occur | produces a microwave, the high frequency power source which drives the said microwave generation means, and the said heating chamber and the said microwave generation means Based on the detection signal of the reflected power detecting means, the reflected power detecting means for detecting the microwave power provided in the microwave transmitting means and detecting the microwave power reflected from the heating chamber to the microwave generating means. In the high-frequency heating apparatus having control means for controlling the high-frequency power source, the control means operates the high-frequency power source at the start of heating to radiate microwaves to the heating chamber, and the microwave generation means from the heating chamber in the state of the reflected power detected the object to be heated based on the behavior of the detection signal of the means for detecting the microwave power reflected into to determine whether liquid or solid Ri, it is possible to perform the heating in accordance with the state of the object to be heated, it is possible to prevent excessive heating of the article to be heated.

In the second invention, in particular, the control means of the first invention determines that the object to be heated is a liquid when the detection signal of the reflected power detection means has an amplitude greater than or equal to a predetermined value at the start of heating. By doing so, bumping and the like accompanying overheating of the object to be heated can be prevented, and safety can be improved.

In the third invention, in particular, the control means of the first invention determines that the object to be heated is solid when the detection signal of the reflected power detection means has an amplitude less than a predetermined value at the start of heating. By this, since heating according to the state of a to-be-heated material can be performed, overheating of a to-be-heated material can be prevented.

In a fourth aspect of the invention, in particular, when the control means of the first and second aspects of the invention determines that the object to be heated is a liquid, the control means controls the high-frequency power source so that microwaves are generated at a high output in the initial stage of heating. By controlling the high-frequency power supply so that the microwave is reduced to a low output after a predetermined time, overheating of the object to be heated can be prevented, and the object to be heated after heating can be finished to high quality. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a schematic configuration diagram of the high-frequency heating device according to the first embodiment of the present invention, and FIG. 2 is a diagram showing an outline of the operation of the high-frequency heating device according to the first embodiment of the present invention. FIG. 3 is a partially enlarged view showing an outline of the operation of the high-frequency heating device according to the embodiment of the present invention.

  In FIG. 1, the high-frequency heating apparatus according to the first embodiment includes a heating chamber 2 provided inside the outer shell 1, and a mounting plate 4 for mounting the article 3 to be heated is disposed in the heating chamber 2. The bottom surface of the heating chamber 2 is formed. A rotating antenna 6 is disposed in a space 5 formed by the outer shell 1 and the mounting plate 4. The rotating antenna 6 radiates microwaves to the heating chamber 2 while rotating through the rotating shaft 7 by the antenna driving motor 8.

  The microwave generation means 9 is driven by a high frequency power supply 10, and the microwave propagates through a waveguide 11 which is a microwave transmission means and is fed to the rotating antenna 6.

  The reflected power detection means 12 is disposed on a part of the wall surface of the waveguide 11 and detects reflected power in which the microwave radiated to the heating chamber 2 returns to the microwave generation means 9 again.

  The swinging means 13 a and the swinging means 13 b are arranged so as to support the mounting plate 4 in the space 5, and swing the object 3 to be heated up and down or left and right through the mounting plate 4. In the present embodiment, the oscillating means 13 a and the oscillating means 13 b are hereinafter expressed as the oscillating means 13.

  The control means 14 controls the high frequency power supply 10 based on the detection signal of the reflected power detection means 12.

  About the high frequency heating apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below. FIG. 2 shows a change in the detection signal of the reflected power detection means 12 when the object to be heated 3 is microwave-heated using the high-frequency heating device in the present embodiment. The object to be heated 3 was 200 g of a normal temperature liquid. FIG. 3 is a partially enlarged view of the heating step A in FIG.

  2 and 3, the heating process includes a heating process A that is the initial stage of heating, a heating process B that is the middle stage of heating, and a heating process C that is the latter stage of heating.

  In the heating step A, when the object to be heated 3 is placed on the placement plate 4 in the heating chamber 2 and a heating start signal is transmitted from the operation unit or the like (not shown) to the control means 14, the control means 14. Starts the operation of the high-frequency power supply 10 and the reflected power detection means 12.

  When the high frequency power supply 10 is driven, the microwave generation means 9 starts oscillation of the microwave. The microwave oscillated from the microwave generation means 9 propagates through the waveguide 11 which is a microwave transmission means and is fed to the rotating antenna 6.

  The microwave radiated from the rotating antenna 6 to the heating chamber 2 is absorbed by the object 3 to be heated and raises the temperature of the object 3 to be heated. However, not all of the microwave is absorbed again. Return to the wave generating means 9.

  The reflected power detection means 12 is composed of, for example, a directional coupler, and detects the reflected power of the microwave that returns to the microwave generation means 9 described above. The reflected power is related to the microwave absorption characteristic of the article 3 to be heated, and the microwave absorption characteristic of the article 3 to be heated changes depending on the temperature, shape, density, and the like.

  The control means 14 starts the operation of the reflected power detection means 12 at the same time as the microwave generation means 9 is driven at the start of heating, and determines whether the state of the article to be heated 3 is liquid or solid.

In addition, when the reflected power detection means 12 detects reflected power, the antenna drive motor 8 of the rotating antenna 6 is stopped. Further, in order to stabilize the detection accuracy of the reflected power detection means 12, when the antenna drive motor 8 stops for the reflected power measurement, it is preferable that the rotating antenna 6 always stops at the same position. Thereby, the detection signal of the reflected power due to the operation of the rotating antenna 6 can be stabilized.

  Here, a method for determining the state of the object to be heated 3 based on the detection signal of the reflected power detection means 12 will be described.

  The reflected power detection means 12 is coupled to the microwave power (so-called reflected power) propagating through the waveguide 11 from the heating chamber 2 in the direction of the microwave generation means 9, and extracts power proportional to the microwave power, Outputs DC converted voltage using a detector diode. The detection signal of the reflected power detection means 12 is input to the control means 14. The control means 14 determines the state of the article to be heated 3 based on the degree of time change of the detection signal.

  The control means 14 stores in advance the microwave power oscillated from the microwave generation means 9, that is, the incident power to the heating chamber 2, by a storage means (not shown) or the like, and a detection signal of the reflected power detection means 12 Based on the above, the absolute value of the reflected power may be calculated using a predetermined relational expression, and the state of the object to be heated 3 may be determined based on the degree of temporal change in the absolute value of the reflected power.

  Further, the ratio between the absolute value of the reflected power and the incident power may be calculated, and the time change of the ratio may be used for the determination.

  When the object to be heated 3 is a liquid, the microwave absorption characteristics change as the shape of the surface (liquid level) changes due to shaking or the like. Therefore, the reflected power changes with time. On the other hand, when the object to be heated 3 is a solid, the shape of the surface does not change, so the microwave absorption characteristics do not change greatly.

  As described above, the reflected power detection means 12 detects whether or not the temporal amplitude of the reflected power continuously exceeds a predetermined value (ΔW in FIG. 3), thereby improving the determination accuracy of the object to be heated. It is something that can be done.

  When the time amplitude of the reflected power propagating through the waveguide 11 is equal to or greater than a predetermined value (ΔW in FIG. 3) (b in FIG. 3 in the present embodiment), the control means 14 indicates that the object 3 to be heated is liquid. When the process proceeds to the heating process B, the high-frequency power supply 10 is controlled so as to increase the microwave output, and when the process proceeds to the heating process C or the end of heating approaches, the microwave output is lowered.

  On the other hand, when the temporal amplitude of the reflected power is less than a predetermined value (a in FIG. 3 in the present embodiment), the control means 14 determines that the article 3 to be heated is not a liquid (that is, a solid). When the process goes to the heating step B, the microwave output is lowered or the high-frequency power supply 10 is controlled so as to continue the heating using DUTY control or the like without changing the microwave output.

  By determining the state of the object to be heated 3 from the time amplitude of the reflected power, in the case of a liquid, by increasing the microwave output, convection is generated in the object to be heated 3 and heating unevenness is eliminated at the same time. Can be shortened.

  In addition, although the microwave output is high at the initial stage of heating, control is performed to reduce the microwave output near the end of heating, so that bumping due to overheating can be prevented.

  On the other hand, when the object to be heated 3 is solid, control using on / off control or the like can be performed, so that temperature unevenness due to local overheating and insufficient heating can be prevented, and the object to be heated at the end of heating can be prevented. It is possible to finish the heated product with high quality.

When the predetermined time elapses and the heating process A is completed, the process proceeds to the heating process B. In the heating process B, even when the heated object 3 is liquid, the surface shape is stable, and the microwave absorption characteristics of the heated object 3 are also stable. Therefore, the waveform of the detection signal of the reflected power detection means 12 The amplitude of is small.
When the reflected power per unit time increases (w / t in FIG. 2 in the present embodiment), the control means 14 determines that the article to be heated 3 has risen to a predetermined temperature, and proceeds to the heating step C.

  Normally, the object to be heated 3 absorbs a large amount of microwaves at room temperature, but when it reaches a predetermined temperature (for example, 60 ° C.), the absorption of the microwaves decreases and the reflected power to the microwave generating means 9 increases. The temperature of the object to be heated 3 can be estimated from the detection signal of the power detection means 12. After the transition to the heating step C, when a predetermined time elapses, the control means 14 stops the high frequency power source 10 and ends the heating.

  If the heating start signal cannot be received within a predetermined time after placing the heated object 3 on the mounting plate 4, the change in the shape of the surface is small even when the heated object 3 is a liquid, so that it can be discriminated as a solid. Since it becomes difficult, when a heating start signal is received after a predetermined time has elapsed, the control means 14 drives the swinging means 13 to determine whether or not the object to be heated 3 is liquid.

  At the same time, the microwave generation means 9, the high frequency power supply 10, and the reflected power detection means 12 are also driven. When driving of the swinging means 13 is started and the temporal amplitude of the detection signal of the reflected power detection means 12 continuously exceeds a predetermined value twice continuously, the control means 14 determines that the article 3 to be heated is liquid. Then, the operation of the swinging means 13 is immediately stopped. Thus, it is possible to prevent problems such as the heated object 3 spilling on the bottom surface of the heating chamber 2.

  In order to determine the state of the article to be heated 3 even during the heating process, the control means 14 may drive the swing means 13. For example, when the object to be heated 3 is in a frozen state, the shape of the surface does not change at the start of heating even if the swinging means 13 is used.

  At that time, when a predetermined time elapses or the object to be heated 3 rises in temperature and the microwave absorption characteristic changes, the control means 14 drives the swinging means 13 to change the shape of the surface. It is determined whether the heated object 3 is liquid or solid.

  The absorption characteristics of microwaves are greatly different between a frozen object to be heated and a room temperature object to be heated. In a frozen state, the object to be heated is hardly absorbed and becomes almost reflected power. On the other hand, the object to be heated at normal temperature easily absorbs microwaves, and thus the reflected power becomes small.

  With this change in reflected power, it is possible to determine whether the object is frozen or at room temperature without using the rocking means 13, but the determination of whether the object to be heated is liquid or solid requires a change in the shape of the surface. As in the present embodiment, it is necessary to arrange the swinging means 13.

  Although not shown in the present embodiment, a temperature detecting means and a time measuring means for measuring the temperature of the heating chamber 2 and the object to be heated 3 are provided, and a predetermined time is passed to determine whether the object to be heated 3 has reached the set temperature. When measuring the elapsed time, the control means 14 may stop the driving of the high-frequency power source 10 and finish the heating.

  Further, in this embodiment, the swinging means 13 is arranged like a column of the mounting plate 4. However, the mounting plate 4 is used as a turntable, and the rotating shaft of the turntable rotates to rotate the object 3 to be heated. It may be configured to swing.

Further, in the present embodiment, the rotating antenna 6 is disposed below the heating chamber 2 and radiates microwaves from below. However, the mounting plate 4 is a turntable and the microwave is radiated from the side surface of the heating chamber 2. It doesn't matter.

  As described above, in the present embodiment, since the state of the object to be heated 3 can be determined from the detection signal of the reflected power detection means 12 and heating according to the state of the object to be heated can be performed, Can be finished with high quality.

  As described above, the high-frequency heating device according to the present invention determines the state of the object to be heated based on the detection signal of the reflected power reflected by the microwave to the microwave generating means, and performs heating according to the state of the object to be heated. Therefore, it can be applied to uses such as a cooking device using microwaves such as a microwave oven and a microwave oven.

DESCRIPTION OF SYMBOLS 1 Outer 2 Heating chamber 3 Object to be heated 4 Mounting plate 5 Space 6 Rotating antenna 7 Rotating shaft 8 Antenna driving motor 9 Microwave generating means 10 High frequency power supply 11 Waveguide (microwave transmission means)
12 Reflected power detection means 13, 13a, 13b Oscillating means 14 Control means

Claims (4)

A heating chamber for storing an object to be heated;
Microwave generation means for generating microwaves;
A high frequency power source for driving the microwave generating means;
Microwave transmission means for coupling the heating chamber and the microwave generation means;
Reflected power detection means for detecting microwave power provided in the microwave transmission means and reflected from the heating chamber to the microwave generation means;
In the high-frequency heating apparatus having control means for controlling the high-frequency power source based on the detection signal of the reflected power detection means,
The control means operates the high-frequency power source at the start of heating to radiate microwaves to the heating chamber, and detects reflected microwave power reflected from the heating chamber to the microwave generating means. A high-frequency heating apparatus characterized by determining whether the state of the object to be heated is liquid or solid based on the behavior of a detection signal. Control means, the detection signal of the reflected power detecting means, if you are amplitude greater than a predetermined value at the start heating of claim 1, wherein determining that the object to be heated is a liquid High frequency heating device. Control means, the detection signal of the reflected power detection means, when the amplitude is less than a predetermined value at the start heating of claim 1, wherein determining that the object to be heated is a solid High frequency heating device. When the control means determines that the object to be heated is a liquid, the control means controls the high-frequency power supply so that microwaves are generated at a high output in the initial stage of heating, and the microwave is set to a low output after a predetermined time has elapsed. high-frequency heating apparatus according to claim 1-2, characterized by controlling the high frequency power source.

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