JP2000346369A - High-frequency heating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily improve heating efficiency, especially, for compact food. SOLUTION: The high-frequency heating equipment is provided with a magnetron 1 for generating high-frequency energy and a waveguide 3 for connecting the magnetron 1 with a heating room 2, an electric field distribution adjustment part 5 consisting of a column shape, conical trapezoid shape, long column shape, or long conical trapezoid shape with an elliptic horizontal section is provided near an upper-wall center part of the heating chamber, and a heating pattern is controlled for increasing an electric field strength at a center part for placing food in the heating chamber, thus easily improving, especially, the heating efficiency of compact food.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency heating apparatus which can easily improve the heating efficiency of small-sized foods when heating foods or the like with high frequency.

[0002]

2. Description of the Related Art In a conventional general high-frequency heating device, a high-frequency radiation port is provided between a magnetron output antenna protruding into a waveguide and the tip of the waveguide. However, it was difficult to greatly adjust the radiation pattern, and it was not easy to improve the heating efficiency.

Therefore, as means for controlling the microwave radiation pattern, for example, Japanese Patent Publication No. Sho 64-8916,
JP-A-08-124670, etc.
No. 4-8916 discloses a high-frequency oscillator (magnetron)
Two slots are provided between the output antenna of the high-frequency oscillator protruding into the waveguide connecting the heating chamber and the heating chamber, and the tip of the waveguide, and the total size of these slots and the partition between the slots is determined by the wavelength used ( 1/2 to 5/4 of free space wavelength)
It is to adjust to. Also, Japanese Patent Application Laid-Open No. 08-12 / 08
No. 4670 discloses a joint (connection surface) between a waveguide and a heating chamber.
Are provided with two slots, both of which are formed so as to pass through the position of 1/4 of the guide wavelength from the tip of the waveguide and to be substantially parallel to the waveguide axis.
Both of these two publications take into account the electromagnetic field pattern of the basic transmission mode TE10 in the waveguide, so that a surface current orthogonal to the magnetic field flows through the joint between the waveguide and the heating chamber, and cuts off this current. Are provided with slots to efficiently radiate high frequencies into the heating chamber.

[0004]

However, in the above-mentioned conventional improvement, the slot is in principle straight, and its length is larger than about 1/2 of the free space wavelength.
No. 8916, two slots are provided horizontally with respect to the waveguide axis and at a distance of 互 い に of the guide wavelength from each other.
Alternatively, as in Japanese Patent Application Laid-Open No. 08-124670, it is necessary to be provided so as to be substantially parallel to the waveguide axis and to face each other at a position along the side surface of the waveguide. There is a problem that it is difficult to fundamentally change the standing wave distribution in the room to improve the heating efficiency.

[0005]

In order to solve the above-mentioned problems, the present invention provides a magnetron for generating high-frequency energy, a heating chamber for accommodating an object to be heated, and a guide for connecting the magnetron to the heating chamber. A high-frequency heating device is composed of a wave tube and an electric field distribution control unit that is provided near the center of the upper wall of the heating chamber, and has a columnar shape, a truncated cone shape, an elliptical column shape, or an elliptical truncated cone shape with a horizontal cross-section. did.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has the above-described structure, and is arranged so that a cylindrical shape, a truncated cone shape, an elongated cylinder shape, or a horizontal cross section is changed from an elongated circular truncated cone shape near the center of an upper wall of a heating chamber. The electric field distribution adjusting section is provided, and the electric field distribution adjusting section adjusts the microwave heating pattern to increase the electric field intensity at the central portion where the food in the heating chamber is placed. This is a significant improvement.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a cross-sectional view of a main part of a high-frequency heating apparatus according to an embodiment of the present invention. Reference numeral 1 denotes a magnetron that generates high-frequency energy, and 1a is coaxially coupled into a waveguide 3 and protrudes. This is a magnetron output antenna. The waveguide 3 is connected to the heating chamber 2, and the high frequency energy of the magnetron 1 is radiated into the heating chamber 2 via the waveguide 3. Reference numeral 4 denotes a heater for cooking an oven or grill. Reference numeral 5 denotes a column-shaped electric field distribution adjusting unit provided so as to protrude from the vicinity of the central portion of the upper wall of the heating chamber 2, reference numeral 6 denotes a turntable for rotatably mounting an object to be heated, and reference numeral 7 denotes a turntable. This is a drive table for rotating the turntable 6. Reference numeral 8 denotes a drive shaft for rotating the drive table 7, reference numeral 9 denotes a drive motor for driving the drive shaft 8, and reference numeral 10 denotes a high-frequency radiation port on a connection surface between the heating chamber 2 and the waveguide 3.

FIG. 2 is a view showing the upper part of the heating chamber 2 as viewed from the direction of the arrow YY ′ in FIG. 1, and the electric field distribution adjusting section 5 is surrounded by a U-shaped heater 4. The radius R of the cylindrical portion of the electric field distribution adjusting section 5 is adjusted, and the turntable 6 is adjusted.
The heating efficiency is improved by increasing the electric field strength at the center where the food is placed. However, the radius R needs to be smaller than the distance D between the terminals so that the electric field distribution adjusting unit 5 does not contact the heater 4, and to have a certain margin more than the distance D so that there is no unevenness in the heating by the heater 4. is there.

FIG. 3 is a diagram showing the dimensions of FIGS. 1 and 2 as A = 320, B = 310, C = 215, D =
120 shows an example of calculation of the maximum electric field intensity value in the central portion (200 mm in diameter) where the probability of placing food on the observation surface 11 (ZX surface) in FIG. 1 when H = 20 mm is set; The electric field strength is calculated by the FDTD (finite difference time domain) method with the magnetron oscillation frequency set to 2,460 MHZ. However, since the purpose is to examine the relative tendency of the electric field strength, detailed dimensional relationships are omitted. As shown here, as the diameter 2 × R of the electric field distribution adjusting section 5 increases, the maximum electric field strength tends to increase, that is, the heating efficiency can be improved.

FIG. 4 is a view showing an embodiment in which the columnar electric field distribution adjusting section 5 shown in FIG. 1 is formed into a long columnar shape, and FIG. 5 is viewed from an arrow YY 'direction in FIG. FIG. 4 is a diagram showing an upper part of a heating chamber 2 which has been heated.

FIG. 6 shows the electric field intensity at the same position as in FIG. 3 when the R dimension of the electric field distribution adjusting section 5 is fixed to 35 mm and the length W of the straight portion of the ellipse is changed in FIGS. It is a figure showing a change of the maximum value, when W = 40 mm,
It can be seen that the maximum value of the electric field intensity is the largest, and the heating efficiency can be significantly improved.

FIGS. 7 and 8 show the case where the high-frequency heating device does not have the electric field distribution adjusting section 5 (R = 0 mm) and the shape of the long cylinder having dimensions H = 20, R = 35 and W = 40 mm, respectively. 3 shows an electric field distribution on the observation surface 11 when the electric field distribution adjusting unit 5 is provided. The central part forming a concentric distribution by the turntable 6 is:
This is a region having a diameter of 200 mm where the probability of placing food is high. By providing the electric field distribution adjusting unit 5, the electric field intensity particularly in the central part is also increased in this region. Therefore,
The smaller the food placed in the center is, the smaller the electric field distribution control unit 5
, The heating efficiency is relatively improved as compared with the case where the electric field distribution adjusting unit 5 is not provided.

FIG. 9 is a view showing an embodiment in which an electric field distribution adjusting section 5 having a horizontal section of an elliptical frustoconical shape is provided so as to protrude into the heating chamber 2, and FIG. FIG.
The figure which shows the upper part of the heating chamber 2 seen from the arrow YY 'direction of
This embodiment has basically the same effects as those of the embodiment shown in FIGS. When the structure here is manufactured by a mold, an appropriate taper 5 'may be provided in consideration of the workability of the metal plate constituting the heating chamber 2.

FIG. 11 shows a heater 4 formed in a rectangular shape and provided on the upper wall of the heating chamber 2, and an electric field distribution adjusting section 5 having a shape of a long truncated cone protrudes into the heating chamber 2 within the rectangle. FIG. 12 is a view showing the upper part of the heating chamber 2 as viewed from the direction of the arrow YY ′ in FIG. 11, and FIG. 12 is a view basically showing FIGS. The same effect as in the embodiment shown in FIG. 10 can be obtained.

FIG. 13 shows an electric field distribution adjusting unit 5 having a shape of a long truncated cone having a straight portion that is not parallel to each side of the heater 4.
FIG. 3 is a view showing an embodiment in which the projections are provided in the heating chamber 2 and are used, for example, when both the performances such as the heating efficiency and the heating unevenness are improved.

FIG. 14 is a view showing an embodiment in which an electric field distribution adjusting section 5 having a truncated cone shape is provided so as to protrude into the heating chamber 2. In this embodiment, basically, FIGS. The same effect as in the case of the second cylindrical shape is obtained.

FIG. 15 shows that the heater 4 is provided outside the heating chamber 2 and the electric field distribution adjusting section 5 having a shape of a long truncated cone is provided in the heating chamber 2.
FIG. 16 is a diagram showing an embodiment in which the heating chamber 2 is provided so as to protrude outwardly from FIG. 16. FIG. 16 is a view showing the upper portion of the heating chamber 2 as viewed from the direction of arrow YY ′ in FIG.
It has been confirmed that the electric field distribution in the inside can be adjusted and the electric field intensity in the center can be increased. In addition, even when the heater 4 is outside the heating chamber 2 as described above, the electric field distribution adjusting section 5 having a cylindrical shape, an elongated cylindrical shape, and a truncated cone shape is protruded to the outside of the heating chamber 2 and the dimensions thereof are adjusted. Needless to say, the electric field strength at the center of the heating chamber can be increased.

When manufacturing the structure shown in FIGS. 9 and 10, 11 and 12, 13 and 14, 15 and 16 by using a mold, the workability of the metal plate constituting the heating chamber 2 is reduced. In consideration of the above, an appropriate taper 5 ′ may be provided.

[0020]

As described above, according to the present invention,
It has a magnetron that generates high-frequency energy and a waveguide that connects this magnetron to the heating chamber, and has a columnar shape, a truncated cone shape, an elliptical cylinder shape, or an oblong horizontal cross section near the center of the upper wall of the heating chamber. By providing an electric field distribution adjusting section having a long truncated cone shape and controlling the heating pattern to increase the electric field intensity at the central portion where the food in the heating chamber is placed, it is possible to easily improve the heating efficiency especially for small foods. Further, a mechanical effect such as preventing thermal deformation of the heating chamber by a heater can be obtained by forming an electric field distribution adjusting section by providing a throttle on the upper wall of the heating chamber toward the inside or outside.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a main part of an embodiment of a high-frequency heating device according to the present invention.

FIG. 2 is a diagram showing an upper part of a heating chamber 2 as viewed from a direction of an arrow YY ′ in FIG.

FIG. 3 is a calculation example of a maximum electric field intensity value in a central portion (200 mm in diameter) where a food is likely to be placed on the observation surface 11 (ZX plane) in FIG. 1;

FIG. 4 is a diagram in the case where the electric field distribution adjusting unit 5 in FIG. 1 is formed in a long cylindrical shape.

FIG. 5 is a diagram when the electric field distribution adjusting unit 5 in FIG. 2 is formed in a long cylindrical shape.

FIG. 6 shows a case where the R dimension of the electric field distribution adjusting unit 5 in FIG.
FIG. 4 is a diagram illustrating a change in the maximum electric field intensity at the same position as in FIG. 3 when the length W of the straight portion of the ellipse is changed while the length is fixed to mm.

FIG. 7 shows an electric field distribution on the observation surface 11 when there is no electric field distribution adjusting unit 5 (R = 0 mm).

FIG. 8 shows an electric field distribution on the observation surface 11 in a case where the electric field distribution adjusting unit 5 is formed in a long cylindrical shape with dimensions H = 20, R = 35, and W = 40 mm, respectively.

FIG. 9 is a diagram when the electric field distribution adjusting unit 5 in FIG. 1 has a horizontal section in the shape of an elliptical truncated cone.

10 is a diagram when the electric field distribution adjusting unit 5 in FIG. 2 has a horizontal cross section in the shape of a long circular truncated cone.

11 is a view showing a case where a heater 4 in FIG. 1 is formed in a rectangular shape, and an electric field distribution adjusting section 5 projects into the heating chamber 2 within the rectangular shape.

FIG. 12 is a view showing a case where the heater 4 in FIG. 2 is formed in a rectangular shape, and the electric field distribution adjusting section 5 projects into the heating chamber 2 within the rectangular shape.

FIG. 13 is a diagram showing a case where the electric field distribution adjusting unit 5 in FIG. 2 is formed in a long truncated cone shape having a straight line portion that is not parallel to each side of the heater 4.

14 is a diagram when the electric field distribution adjusting unit 5 in FIG. 2 has a truncated cone shape.

FIG. 15 is a view showing a case where the heater 4 in FIG. 1 is provided outside the heating chamber 2 and the electric field distribution adjusting unit 5 is formed in a long truncated cone shape.

FIG. 16 is a view showing a case where the heater 4 in FIG. 2 is provided outside the heating chamber 2 and the electric field distribution adjusting section 5 is formed into a long truncated cone shape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetron 1a Magnetron output antenna 2 Heating chamber 3 Waveguide 4 Heater 5 Electric field distribution adjusting part 5 'taper 6 Turntable 7 Drive table 8 Drive shaft 9 Drive motor 10 High frequency radiation port

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K090 AA01 AA02 AB02 BA01 BB01 CA01 3L086 AA01 BB05 DA06

Claims (1)

[Claims] 1. A magnetron (1) for generating high-frequency energy, a heating chamber (2) in which an object to be heated is stored, and a waveguide (3) connecting the magnetron to the heating chamber.
And an electric field distribution adjusting section (5) provided near the center of the upper wall of the heating chamber and having a columnar shape, a truncated cone shape, an elliptical column shape, or a truncated conical shape having an elliptical horizontal cross section. A high-frequency heating device, characterized in that: