JP2015162321A - Radio frequency heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio frequency heating device in which generated microwave power can be efficiently supplied from a waveguide to a rotary antenna to couple the microwave power to the rotary antenna.SOLUTION: A rotary antenna 100 of a radio frequency heating device 1 has a short-circuit wall 102 as a shield face, and a coupling hole 108 formed in a wall surface (lower surface wall 104) which is substantially vertical to the short-circuit wall 102 adjacent to a waveguide 50, and an inner conductor 101 which is inserted through the coupling hole 108 and supported in contact with the inner wall of a rectangular cylindrical pipe. The rotary antenna 100 is configured in the form of a rectangular cylindrical pipe having the short-circuit wall 102 as a bottom. The rotary antenna 100 has an open face serving as a radiation port of microwave energy, and the open face 107 faces the short-circuit wall 102 through the inner conductor 101.

Description

  The present invention relates to a high-frequency heating apparatus that irradiates an object to be heated with microwave power.

  There is a high-frequency heating device that radiates microwave energy into a heating chamber and heats food. In the heating method using the microwave power, the microwave energy is directly transmitted to the inside of the irradiation object, so that rapid and highly efficient heating can be realized. A magnetron is generally used for a microwave oscillation device.

  Recently, from the viewpoint of increasing the effective volume of the heating chamber and reducing the size of the apparatus, a system using a rotating antenna instead of rotating the object to be heated itself is often used without using a turntable. As a technique for supplying microwaves into a heating chamber using a rotating antenna, a microwave transmitting waveguide is provided, and a rotating antenna is provided in an opening that penetrates from the waveguide to the heating chamber. Derived into the heating chamber and emitted.

Patent Document 1 describes a high-frequency heating device in which a rotating antenna housing portion is formed on the ceiling wall surface of a heating chamber so as to protrude outward, and the rotating antenna is housed in the rotating antenna housing portion. In the high-frequency heating device described in Patent Document 1, after the microwave energy guided by the fixed waveguide is coupled to the rotating antenna, the microwave energy is radiated from the excitation opening of the rotating antenna into the heating chamber and mounted on the mounting table. High-frequency heating foods.
The rotating antenna has a box shape with an open top surface, and is provided so as to pass through the radio power feeding port of the rotating antenna housing and the radio power feeding port of the fixed waveguide and face the radio power feeding port substantially vertically. The rotating shaft made of a dielectric is fixed to the bottom surface of the rotating antenna, and the upper surface opening of the rotating antenna is held by the rotating shaft in an upward state facing the upper surface of the rotating antenna storage portion. In addition, an excitation port is formed on the bottom of the rotating antenna on the side opposite to the end on which the rotating shaft is fixed, and the microwave generated by the magnetron and transmitted through the fixed waveguide is coupled. Then, microwaves are radiated from the excitation opening of the rotating antenna into the heating chamber. In addition, a flange is provided at the narrow surface end perpendicular to the bottom surface of the rotating antenna so as to face the top surface of the fixed waveguide housing portion and at a right angle to the narrow surface end in the direction toward the outer side of the rotating antenna. Attempts are made to suppress leakage from the upper surface gap between the upper portion and the fixed waveguide housing portion facing this portion.
In Patent Document 1, the radio wave feeding port of the fixed waveguide is provided so as to face the upper surface opening of the rotating antenna. In order to rotate the rotating antenna, the rotating antenna is rotatably supported by a dielectric rotating shaft at a certain distance from the fixed waveguide.

  In Patent Document 2, a rotating antenna having a substantially circular truncated conical antenna dome having a shaft element provided through a lead-out hole on the top surface of the antenna dome and a substantially circular flat plate element coupled to the shaft element is arranged. A microwave heating apparatus is described. In the microwave heating apparatus described in Patent Document 2, a metal shaft element is fixed to a metal plate element which is a rotating antenna, and the shaft element penetrates the lead-out hole and protrudes into the waveguide to guide the waveguide. It is described that a rotor made of a rotatable dielectric material penetrating through the waveguide is held in the waveguide without being in contact with the upper wall of the waveguide.

Japanese Utility Model Publication No. 62-67495 JP 2013-37795 A

  Since the high-frequency heating device described in Patent Document 1 is configured to rotatably support the rotating antenna with a dielectric rotating shaft at a certain distance from the fixed waveguide in order to rotate the rotating antenna. This dielectric rotating shaft makes it difficult to couple the microwave radiated from the radio wave feed port of the fixed waveguide to the radio wave feed port of the rotating antenna. Even if the microwave is coupled to the rotating antenna, There is a problem that most of the microwaves leak from the gap between the provided flange and the upper surface of the rotating antenna housing facing the flange. In addition, since the TE mode (Transverse Electric mode) wave necessary for transmitting the microwave in the rotating antenna does not occur, the microwave cannot be radiated into the heating chamber from the excitation opening of the rotating antenna. is there.

  Since the microwave heating apparatus described in Patent Document 2 has a configuration using a rotating antenna in which a metal shaft element is fixed to a flat plate element, according to experiments and the like, the coupling degree of microwave power is inferior, It has been found that the generated microwave power cannot be efficiently coupled to the rotating antenna.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a high-frequency heating device capable of efficiently supplying and coupling generated microwave power from a waveguide to a rotating antenna. To do.

  In order to solve the above-described problems, a high-frequency heating device of the present invention includes a heating chamber that accommodates an object to be heated, a high-frequency supply chamber that is provided on one surface of the heating chamber, and a microwave supply source that generates microwave energy. A waveguide for transmitting microwave energy generated by the microwave supply source, a coupling hole for coupling the high-frequency supply chamber and the waveguide, and one side penetrating the coupling hole on the high-frequency supply chamber An inner conductor provided with the other side facing the waveguide, a box-shaped metal rotating antenna housed in the high-frequency supply chamber, and a drive for rotating the rotating antenna around the inner conductor The rotary antenna includes a hole through which the inner conductor penetrates at a position corresponding to the coupling hole, and the microwave energy introduced into the rotary antenna by the inner conductor and the hole is centrifuged. Direction It characterized by having a a radiation opening for emitting a.

  According to the present invention, there is provided a high frequency heating apparatus capable of efficiently supplying and coupling generated microwave power from a waveguide to a rotating antenna.

It is sectional drawing which shows the structure of the high frequency heating apparatus which concerns on the 1st Embodiment of this invention. It is a principal part cross-sectional perspective view of the rotating antenna of the high frequency heating apparatus which concerns on the said 1st Embodiment. It is a perspective view of the rotating antenna of the high frequency heating device according to the first embodiment. It is an expanded sectional view of the rotating antenna electric power feeding part of the high frequency heating apparatus which concerns on the said 1st Embodiment. It is a figure which shows the coupling characteristic analysis result by the inner conductor of a rotating antenna of the high frequency heating apparatus which concerns on the said 1st Embodiment, and a short circuit wall distance. It is a principal part cross-sectional perspective view of the rotating antenna which made the shape of the inner conductor of the high frequency heating apparatus which concerns on the said 1st Embodiment into the L shape. It is a principal part cross-sectional perspective view of the rotating antenna which made the shape of the inner conductor of the high frequency heating apparatus which concerns on the said 1st Embodiment into the T shape. It is a figure which shows the analysis result of the combined power of the rotating antenna of the high frequency heating apparatus which concerns on the said 1st Embodiment, and a prior art example. It is a perspective view of the rotating antenna of the high frequency heating apparatus which concerns on the 2nd Embodiment of this invention. It is a top view of the rotating antenna which made the vertical wall of the high frequency heating apparatus concerning the said 2nd embodiment into a curved surface. It is a top view of the rotating antenna which has the other opening part of the high frequency heating apparatus which concerns on the said 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing the configuration of the high-frequency heating device according to the first embodiment of the present invention. The high-frequency heating device of this embodiment is an example applied to a microwave oven having a waveguide that transmits microwave power from a microwave oscillation device in a metal heating box that houses an object to be heated.

  As shown in FIG. 1, the high-frequency heating device 1 includes a heating chamber 10 that houses an object to be heated S, a heated object mounting plate 20 made of a dielectric that is installed on a bottom surface 10 a of the heating chamber 10, and a heated object. A high-frequency supply chamber 30 disposed below the object placement plate 20 and substantially at the center of the bottom surface of the heating chamber 10, and a magnetron 40 (microwave supply) installed at a lower side of the high-frequency supply chamber 30 to generate microwave energy. Source) and a waveguide 50 for transmitting the microwave power generated by the magnetron 40. The high-frequency heating device 1 includes a coupling hole 31 that is opened at a substantially central portion of the bottom surface 30 a of the high-frequency supply chamber 30 in order to radiate the microwave energy guided to the waveguide 50 to the high-frequency supply chamber 30. An inner conductor 101 provided through the center of 31 and facing substantially vertically into the high-frequency supply chamber 30; a metal rotary antenna 100 housed in the high-frequency supply chamber 30 and connected to one end of the inner conductor 101; A dielectric shaft 60 connected to the inner conductor 101 in the waveguide 50 and a drive unit 70 that rotationally drives the dielectric shaft 60 are provided.

  The high-frequency heating device 1 of the present embodiment is provided with a high-frequency supply chamber 30 that houses a rotating antenna 100 that eliminates standing waves in the heating chamber 10 at the bottom (bottom) of the heating chamber 10. This is an example in which a magnetron 40 and a waveguide 50 are arranged in the lower part. The high-frequency heating device 1 may have a configuration in which the high-frequency supply chamber 30 that houses the rotating antenna 100 is provided on the upper portion or the side surface of the heating chamber 10.

<Rotating antenna>
FIG. 2 is a cross-sectional perspective view of the main part of the rotating antenna of the high-frequency heating device according to the present embodiment. FIG. 3 is a perspective view of the rotating antenna of FIG.
As shown in FIGS. 2 and 3, the rotating antenna 100 has a rectangular waveguide structure with a rectangular cross section and a short-circuit wall 102 on one end surface. Specifically, the rotating antenna 100 has a rectangular tube shape made of metal with a short-circuited wall 102 serving as a shielding surface as a bottom, and a coupling provided on a wall surface (lower wall 104) substantially perpendicular to the short-circuit wall 102. A hole (hole) 108 and an inner conductor 101 that is inserted through the coupling hole 108 and is supported in contact with the inner wall of the rectangular tube.

  The short-circuit wall 102 has a rectangular shape whose upper and lower sides are longer than the left and right sides. The rotating antenna 100 has a configuration in which an upper surface wall 103, a lower surface wall 104, and vertical walls 105 and 106 that connect them vertically are provided on four sides of the short-circuit wall 102 at right angles. More specifically, in the rotating antenna 100, the upper surface wall 103, the lower surface wall 104, and the vertical walls 105 and 106 extend from the four rectangular sides of the short-circuit wall 102 toward the microwave emission side (opening surface 107 side). Is configured to do. Since the rotating antenna 100 has a rectangular parallelepiped shape, the open surface 107 is configured in a rectangular shape having the same size as the short-circuit wall 102.

  The rotating antenna 100 has a rectangular tube shape with a shorted wall 102 as a bottom, and an opening of the rectangular tube is an open surface 107 serving as a microwave energy radiation port. The open surface 107 faces the short-circuit wall 102 with the inner conductor 101 interposed therebetween, and is a radiation port that radiates microwave energy introduced into the rotating antenna 100 in the centrifugal direction.

  The lower wall 104 is provided so as to be spaced upward from the waveguide 50, and forms a circular coupling hole 108 that is a hole at a predetermined distance from the short-circuit wall 102. The coupling hole 108 passes through the center thereof. Thus, the inner conductor 101 is inserted. The inner conductor 101 passes through the coupling hole 51 of the waveguide 50, the coupling hole 31 of the bottom surface 30 a of the high frequency supply chamber 30, and the coupling hole 108 of the lower surface wall 104. One end of the inner conductor 101 is in contact with the inner surface of the upper surface wall 103 of the rectangular parallelepiped (box-shaped) rotating antenna 100, and the inner conductor 101 is fixed substantially vertically to the inner surface of the upper surface wall 103. The other end of the inner conductor 101 is supported by a dielectric shaft 60 connected in the waveguide 50. Since one end of the inner conductor 101 comes into contact with the inner surface of the upper surface wall 103 of the rotating antenna 100 and is fixed substantially vertically, the rotating antenna 100 is supported by the dielectric shaft 60 connected in the waveguide 50.

Thus, the rotary antenna 100 is a substantially rectangular parallelepiped rotary antenna having one open surface 107. The rotating antenna 100 has a configuration in which only a rectangular open surface 107 serving as a microwave energy radiation port and a coupling hole 108 formed in the lower surface wall 104 are opened, and the other surface is covered with a metal wall. Further, the inner conductor 101 of the rotating antenna 100 passes through the coupling hole 108 and is fixed to the inner surface of the upper surface wall 103 of the rotating antenna 100.
The length of the short side of the short-circuit wall 102 of the rotating antenna 100 and the distance from the short-circuit wall 102 to the center of the coupling hole 108 will be described later.

Hereinafter, the operation of the high-frequency heating device 1 configured as described above will be described.
As shown in FIGS. 1 to 3, the inner conductor 101 contacts the inner surface of the upper surface wall 103 of the rotating antenna 100 and is fixed substantially vertically. Here, the inner conductor 101 only needs to be fixed to the inner wall of the rotating antenna 100, and is not limited to a fixed position or the number of fixed places.

  As shown in FIG. 1, the microwave energy generated in the magnetron 40 is guided to the waveguide 50 and passes through the coupling hole 51 of the waveguide 50 and the coupling hole 31 of the bottom surface 30 a of the high-frequency supply chamber 30. Propagated to the rotating antenna 100 by coaxial mode coupling with the antenna 101. The waveguide 50 transmits the microwave generated by the magnetron 40 in the TE mode (Transverse Electric mode). Here, the portion of the inner conductor 101, that is, the path from the waveguide 50 to the rotating antenna 101 via the inner conductor 101 constitutes a coaxial waveguide converter (the propagation mode is a TEM mode (Transverse Electro Magnetic mode)). The microwave energy propagated to the rotating antenna 100 (becomes TE mode again) is radiated from the open surface 107 of the rotating antenna 100 into the heating chamber 10 through the high-frequency supply chamber 30 and the heated object placing plate 20. . Since the rotation antenna 100 is controlled to rotate by the drive unit 70, the microwave from the rotation antenna 100 is radiated outward (centrifugal direction) from the open surface 107.

  The high-frequency heating device 1 includes a substantially rectangular parallelepiped (box-shaped) rotating antenna 100 having one open surface 107, so that the bottom surface 30 a of the high-frequency supply chamber 30 and the bottom wall 104 of the rotating antenna 100 facing the bottom surface 30 a are opposed. The leakage of the microwave from the gap of the coupling hole 108 can be reduced, and after the mode is once changed from the waveguide 50 for transmitting the microwave generated in the magnetron 40 in the TE mode, the rotating antenna 100 is set to the same TE mode. A fundamental microwave can be supplied, and the degree of coupling between the two becomes high. For this reason, since the microwave is efficiently irradiated to the inside of the heating chamber 10 to heat the article to be heated S, a high energy saving effect is obtained. Further, since the rotating antenna 100 is rotated, the standing wave is also eliminated, and the object to be heated S can be heated without unevenness.

Next, the shape and antenna characteristics of the rotating antenna 100 will be described.
As shown in FIG. 3, the rotary antenna 100 has a rectangular waveguide structure having a rectangular cross section and a short-circuit wall 102 on one end face. In the rotating antenna 100, the length of the long side of the rectangular cross section is longer than λ / 2 (λ is the wavelength of the microwave) and shorter than λ so that the microwave energy propagates in the TE mode in the rotating antenna 100. . Further, the rotating antenna 100 has a short side height shorter than λ / 2.

FIG. 4 is an enlarged cross-sectional view of the rotating antenna power feeding unit of the high-frequency heating device 1.
As shown in FIG. 4, in the rotating antenna 100, the distance between the center of the inner conductor 101 and the short-circuit wall 102 is approximately λg / 8 (λg is the in-tube wavelength of the microwave propagating in the rotating antenna 100).

FIG. 5 is a diagram illustrating an analysis result of the coupling characteristics depending on the distance between the inner conductor 101 and the short-circuit wall of the rotating antenna 100. FIG. 5A illustrates the inner conductor and the short-circuit wall distance a, and FIG. The analysis results of the coupling characteristic S21 (dB) according to the inner conductor and the short-circuit wall distance a are respectively shown.
The degree of coupling between the waveguide 50 and the rotating antenna 100 is represented by a coupling characteristic S21. As shown in FIG. 4, the coupling characteristic S21 is a logarithm of the ratio of the microwave Pin fed to the port 1 of the waveguide 50 and the microwave Pout radiated from the port 2 of the rotating antenna 100. It is.

  As shown in FIG. 5B, the coupling characteristic S21 has a smaller loss in the middle as it approaches 0 dB, that is, the degree of coupling between the waveguide 50 and the rotating antenna 100 increases. As shown in FIG. 4, in the rotating antenna 100 of the present embodiment, when the distance between the inner conductor 101 and the short-circuit wall 102 is λg / 8, the coupling characteristic S21 is −0.35 (dB), and the coupling degree is the maximum. I understand that In this analysis, the frequency f of the applied microwave was 2460 (MHz) and λ = 122 mm in terms of wavelength.

As described above, the high-frequency heating device 1 of the present embodiment includes the high-frequency supply chamber 30 provided on one surface of the heating chamber 10 that accommodates the object to be heated, the waveguide 50 that transmits the generated microwave power, A coupling hole 31 provided on one surface of the high-frequency supply chamber 30, an inner conductor 101 provided through the coupling hole 31 so as to face the high-frequency supply chamber 30 substantially vertically, and an inner conductor accommodated in the high-frequency supply chamber 30 Rotating antenna 100 supported by 101, and drive unit 70 that rotationally drives shaft 60 connected to inner conductor 101 in waveguide 50. The rotating antenna 100 has the configuration described above.
With this configuration, the microwave energy generated in the magnetron 40 is transmitted in the TE mode in the waveguide 50, and is transmitted in the TEM mode in the path from the waveguide 50 to the rotating antenna 101 via the inner conductor 101. The TE-mode fundamental wave microwave energy is again supplied from the inner conductor 101 in 100 to the rotating antenna 100. Thus, the rotating antenna 100 having the inner conductor 101 constitutes an efficient coaxial waveguide converter.

  Therefore, the microwave generated in the magnetron 40 can be supplied from the waveguide 50 transmitting in the TE mode to the rotating antenna 100 as the same TE-mode fundamental microwave, so that the degree of coupling between the two becomes high. For this reason, microwaves can be efficiently irradiated into the heating chamber to heat the object to be heated, and a high energy saving effect can be obtained. Further, by rotating the rotating antenna 100, the standing wave in the rotating antenna 100 can be eliminated and the object to be heated S can be heated evenly.

  In the present embodiment, in the rotating antenna 100, the length of the short side of the short-circuit wall 102 is approximately λ / 2 or less of the oscillation wavelength λ of the magnetron 40. More specifically, in the rotating antenna 100, the length of the long side is longer than λ / 2 and shorter than λ, and the height of the short side is shorter than λ / 2. As a result, a vertical electric field is not generated on the vertical walls 105 and 106, so that high-order mode microwaves are not generated. Since the microwave of the same TE mode can be supplied to the rotating antenna from the waveguide 50 that transmits the microwave generated in the magnetron 40 in the TE mode, the degree of coupling is increased, and the bottom surface 30a of the high frequency supply chamber is increased. There is an effect that the leakage of the microwave from the gap of the lower surface wall 104 of the rotating antenna 100 facing this can be reduced.

  In the present embodiment, the distance from the short-circuit wall 102 to the center of the coupling hole 108 is approximately λg / 8 of the guide wavelength λg with respect to the oscillation wavelength λ of the magnetron 40. By setting the distance between the center of the coupling hole 108 and the short-circuit wall 102 to λg / 8, the microwave easily propagates in the direction of the open surface 107, so that the microwave between the inner conductor 101 of the rotating antenna 100 and the short-circuit wall 102 can be obtained. Loss is reduced. Therefore, as shown in FIG. 5B, the coupling power (W) can be increased, and the microwave energy generated by the magnetron 40 can be efficiently transmitted to the rotating antenna 100.

[Modification]
<L-shaped inner conductor>
FIG. 6 is a perspective cross-sectional view of a rotating antenna in which the shape of the inner conductor of the high-frequency heating device 1 according to the first embodiment is L-shaped.
As shown in FIG. 6, the rotating antenna 110 includes an L-shaped inner conductor 111 having an L-shaped bent end at a right angle instead of the linear inner conductor 101 shown in FIGS. 1 to 3. In addition, the structure which accommodates the rotation antenna 110 is the same as that of FIG.
The L-shaped inner conductor 111 includes a vertical inner conductor 111a inserted through a coupling hole 108 provided on a wall surface substantially perpendicular to the short-circuit wall 102, and a horizontal inner conductor 111b perpendicular to the vertical inner conductor 111a. . The L-shaped inner conductor 111 has a configuration in which the tip of the vertical inner conductor 111a and the horizontal inner conductor 111b are coupled at a right angle, and the tip of the horizontal inner conductor 111b is fixed to the short-circuit wall 102.

<T-shaped inner conductor>
FIG. 7 is a perspective cross-sectional view of a rotating antenna in which the shape of the inner conductor of the high-frequency heating device 1 according to the first embodiment is T-shaped.
As shown in FIG. 7, the rotating antenna 120 includes a T-shaped inner conductor 121 having a T-shaped tip instead of the linear inner conductor 101 shown in FIGS. In addition, the structure which accommodates the rotation antenna 120 is the same as that of FIG.
The T-shaped inner conductor 121 includes a vertical inner conductor 121a inserted through a coupling hole 108 provided on a wall surface substantially perpendicular to the short-circuit wall 102, and a horizontal inner conductor 121b perpendicular to the vertical inner conductor 121a. . In the T-type inner conductor 121, the tip of the vertical inner conductor 121a is coupled to the center of the horizontal inner conductor 121b at a right angle, and one end and the other end of the horizontal inner conductor 121b are fixed to the inner walls of the vertical walls 105 and 106. It becomes the composition.

FIG. 8 is an explanatory diagram for comparing the microwave analysis results of the combined power (W) of the rotating antennas 100, 110, 120 of the present embodiment and the conventional example. In FIG. 8, the coupling power (W) refers to the open surface 107 of the rotating antenna 100, 110, 120 when the microwave power Pin = 1000 (W) is supplied to the port 1 of the waveguide 50 shown in FIG. 4. This is the microwave power Pout (W) radiated from the port 2.
The microwave analysis result of the coupling power (W) of the rotating antenna 100 (see FIGS. 1 to 3) is indicated by a two-dot chain line in FIG. 8, and the coupling power (W) of the rotating antenna 110 (see FIG. 6) is microscopic. The wave analysis result is indicated by a chain line in FIG. Moreover, the microwave analysis result of the coupling power (W) of the rotating antenna 120 (see FIG. 7) is shown by the solid line in FIG. 8, and the microwave of the coupling power (W) of the conventional example (known example) of Patent Document 1 is shown. The analysis result is indicated by a round dotted line in FIG.

  As shown in FIG. 8, the rotating antennas 100, 110, and 120 of this embodiment are approximately 200 (W) at frequencies 2450 (MHz) to 2470 (MHz) as compared with the conventional example (see the dotted line in FIG. 8). It can be seen that the coupling power is improved. Further, as shown in FIG. 8, the rotating antenna 120 (see FIG. 7) having the T-shaped inner conductor 121 has the largest combined power (W) and the rotating antenna 110 (see FIG. 6) having the L-shaped inner conductor 111. The rotating antenna 100 (see FIG. 3) having the inner conductor 101 is next to it. From the viewpoint of improving the coupling power (W), it goes without saying that the rotating antenna 120 (see FIG. 7) having the T-shaped inner conductor 121 is preferably used, but has the linear inner conductor 101 having a simple structure. Even when the rotating antenna 100 (see FIG. 3) or the rotating antenna 110 (see FIG. 6) having the L-shaped inner conductor 111 whose tip is refracted at a right angle is used, a significant coupling power is obtained as compared with the conventional example (known example). (W) can be improved.

  Note that the bent portions of the box-shaped rotating antennas 100, 110, and 120 are not necessarily right angles but may be curved surfaces. Further, it may be produced by producing a cylindrical portion or a box portion having one surface opened by deep drawing or pressing and welding a flat plate to the opening surface (opening portion). Moreover, you may produce by welding a flat plate to the opening surface of a rectangular tube.

(Second Embodiment)
FIG. 9 is a perspective cross-sectional view of the rotating antenna of the high-frequency heating device according to the second embodiment of the present invention.
As shown in FIG. 9, the rotating antenna 130 includes a lower surface wall 134 having a coupling hole 108 that penetrates the inner conductor 101, and an upper surface wall 133 that is substantially parallel to the lower surface wall 134 and to which the inner conductor 101 is fixed. Two surfaces of the lower wall 134 and the upper wall 133 are formed as trapezoidal planes. That is, the rotating antenna 130 is configured by forming the upper surface wall 103 and the lower surface wall 104 of the rotating antenna 100 of FIGS. 1 to 3 in a trapezoidal shape with the open surface 137 serving as a trapezoid bottom. The rotating antenna 130 is configured by a rectangle having a cross section with different long sides in the open surface 137 and the short-circuit wall 102, and the long side of the open surface 137 is longer than the long side of the short-circuit wall 102. In particular, the length of the long side of the short-circuit wall 102 is set to a length of ½ or more of the wavelength of the microwave to be supplied.
In addition, the box-shaped cross section which goes to the open surface 137 by the lower surface wall 134, the upper surface wall 133, and the vertical walls 105 and 106 is a rectangle. Further, the lower surface wall 134 and the short-circuit wall 102, and the upper surface wall 133 and the short-circuit wall 102 are connected to each other at a right angle.

As described above, the rotating antenna 130 according to the present embodiment further reduces the microwave loss between the waveguide 50 and the rotating antenna 130 by configuring the lower wall 133 and the upper wall 133 in a trapezoidal plane. be able to. Further, reflected waves can also be suppressed, and the degree of coupling can be improved.
Therefore, as shown in FIG. 1, the microwave energy generated by the magnetron 40 can be efficiently transmitted to the rotating antenna 130.

FIG. 10 is a plan view of a rotating antenna having a curved vertical wall.
As shown in FIG. 10, the rotating antenna 140 includes a lower surface wall 144 having a coupling hole 108 that penetrates the inner conductor 101, an upper surface wall 143 that is substantially parallel to the lower surface wall 144 and to which the inner conductor 101 is fixed, and a lower surface wall 144. Curved vertical walls 145 and 146 connecting the upper wall 143 and the upper surface wall 143. The vertical walls 145 and 146 are curved surfaces whose inner surfaces are recessed, and the lower wall 134 and the upper wall 133 are curved at the ends so as to match the curved shape of the vertical walls 145 and 146.
Here, in the rotating antenna 140, the lateral width A of the short-circuit wall 102 is set to a length that is ½ or more of the wavelength of the microwave to be supplied.

FIG. 11 is a plan view of the rotating antenna in which another open surface is provided on any one of the short-circuit wall, the lower surface wall, the upper surface wall, and the vertical wall of the rotating antenna.
As shown in FIG. 11, the rotating antenna 150 further includes another opening 151 in addition to the opening surface 107 in the upper surface wall 103. In FIG. 11, the opening 151 is provided in the top wall 103 and the quantity is three.
For example, in addition to the open surface 107, the rotating antenna 150 has a length of ½ or more of the cutoff wavelength on the wall surface side (in this case, the upper surface wall 103) facing the object to be heated S of the waveguide-shaped rotating antenna 150. A plurality of slit-shaped openings 151 having a right angle with respect to the propagation direction of the microwave or an appropriate angle within 0 to 90 degrees are provided.
In this case, if the slit-shaped opening 151 is provided so as to have an appropriate angle with respect to the propagation direction of the microwave, the microwave radiated from each opening 151 is independent of the phase, Therefore, the light is emitted from the plurality of openings 151 without being canceled.

Note that the shape, state, arrangement, and number of the openings 151 are determined in relation to uneven heating of the article S to be heated in the heating chamber 10 (see FIG. 1). Unevenness can also be suppressed.
For example, in addition to the open surface 107, a slit-shaped opening having a length of ½ or more of the cutoff wavelength is provided on the wall surface (upper surface wall 103) facing the object to be heated S of the waveguide-shaped rotating antenna 100. A plurality may be provided at right angles to the wave propagation direction or at an appropriate angle within 0 to 90 degrees.
In this case, if the slit-shaped opening is provided with an appropriate angle with respect to the propagation direction of the microwave, the microwave radiated from each opening will be canceled (regardless of the phase). Without being emitted from a plurality of openings.
Further, the shape and state of the open surface, or the arrangement and number of openings are determined in relation to the uneven heating of the article S to be heated in the heating chamber 10, and the uneven heating is suppressed by adjusting these. Is also possible.

  Further, the L-type inner conductor 111 (see FIG. 6) and the T-type inner conductor 121 (see FIG. 7) may be applied to the second embodiment, and the same effects as in the first embodiment can be obtained. Can do.

  In addition, this invention is not limited to the structure described in each said embodiment, The structure can be suitably changed unless it deviates from the summary of this invention described in the claim.

  For example, in each of the above embodiments, a magnetron is used as a microwave supply source that generates microwave energy, but other microwave oscillation devices that oscillate and output microwaves include electron tubes such as a klystron and a gyrotron, A microwave generator using a semiconductor as the oscillation source may be used. Further, the material, shape, structure, and the like of the waveguide and the rotating antenna are examples, and any materials may be applied.

  Further, for example, in the rotating antenna 100 shown in FIG. 2, an aspect in which the open surface 107 is not provided parallel to the short-circuit wall 102, an aspect in which the upper surface wall 103 and the lower surface wall 104 are different, and an aspect in which the open surface 107 is curved. However, the same effect can be obtained.

  The above-described exemplary embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. . Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each exemplary embodiment.

DESCRIPTION OF SYMBOLS 1 High frequency heating apparatus 10 Heating chamber 30 High frequency supply chamber 31 Coupling hole 40 Magnetron (microwave supply source)
50 Waveguide 60 Dielectric shaft 70 Drive unit 100, 110, 120, 130, 140, 150 Rotating antenna 101 Inner conductor 102 Short-circuit wall 103, 133, 143 Upper surface wall 104, 134, 144 Lower surface wall 105, 106, 145 146 Vertical wall 107,137 Open surface (radiant opening)
108 Bonding hole (hole)
111 L-type inner conductor (inner conductor)
111a, 121a Vertical inner conductor 111b, 121b Horizontal inner conductor 121 T-type inner conductor (inner conductor)
151 Opening (radiation port)

Claims (5)

A heating chamber for storing an object to be heated;
A high-frequency supply chamber provided on one surface of the heating chamber;
A microwave source for generating microwave energy;
A waveguide for transmitting microwave energy generated by the microwave source;
A coupling hole for coupling the high-frequency supply chamber and the waveguide;
An inner conductor provided so that one side thereof penetrates the coupling hole and the other side faces the waveguide in the high-frequency supply chamber;
A box-shaped metal rotating antenna housed in the high-frequency supply chamber;
A drive unit that rotationally drives the rotating antenna around the inner conductor; and
The rotating antenna is
A hole through which the inner conductor passes at a position corresponding to the coupling hole;
A high-frequency heating apparatus comprising: a radiation port for radiating microwave energy introduced into the rotating antenna by the inner conductor and the hole portion in a centrifugal direction. The rotating antenna includes a short-circuit wall that is a shielding surface, a hole provided in a wall surface that is substantially perpendicular to the short-circuit wall adjacent to the waveguide, and is inserted through the hole and contacts the inner wall. And the inner conductor supported by
The high-frequency heating device according to claim 1, wherein the high-frequency heating device has a rectangular tube shape with the short-circuit wall as a bottom. The rotating antenna is
The high-frequency heating device according to claim 1, wherein the high-frequency heating device has an open surface serving as a microwave energy radiating port, and the open surface faces the short-circuit wall with the inner conductor interposed therebetween. The rotating antenna is
4. The high-frequency heating device according to claim 1, wherein a length of a short side of the short-circuit wall is approximately λ / 2 or less of an oscillation wavelength λ of a microwave supply source. . 5. The distance from the short-circuit wall to the center of the coupling hole is approximately λg / 8 of the in-tube wavelength λg with respect to the oscillation wavelength λ of the microwave supply source. The high-frequency heating device described in 1.

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