JP2902911B2 - microwave - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven.

[0002]

2. Description of the Related Art Conventionally, this kind of microwave oven has been
No. -50122. The magnetron includes a magnetron mounted so as to protrude an antenna into a heating chamber, and a flat electrode serving as a radiation antenna mounted to the magnetron antenna with screws or the like.
In which it is mounted parallel to the heating chamber wall surface and the flat plate electrode in the mounting.

However, there is a possibility that a discharge may occur between the antenna and the plate electrode depending on how the screws are attached. Therefore, a radiation antenna as described below has been considered.

This is shown in FIGS. 1, 7 and 8. 1 is an exterior of a microwave oven, 2 is a cavity for storing a food 3 to be heated from a front opening (not shown), 4 is a placing plate for placing the stored food 3 disposed in the cavity 2 and Reference numeral 5 denotes a motor for attaching the placing plate 4 to a rotating shaft 6 penetrating the bottom surface 2a of the cavity 2 and rotating the placing plate 4 during cooking. In addition, since the placing plate 4 rotates during cooking, it is generally called a turntable.

[0005] 7 is a waveguide provided on the side wall 2b of the cavity 2, 8 is a magnetron mounted on the wall surface facing the cavity 2 of the waveguide 7, that is, a magnetron mounted on the bottom surface 7a, 9 is a waveguide on the side wall 2b of the cavity. It is a protection plate made of a mica plate that closes the tube opening.

The waveguide 7 has a substantially trapezoidal cross section in which the opening area on the side of the cavity 2 is large and becomes smaller as the distance increases.
For example, it has a substantially truncated conical shape, and the diameter of the wall surface facing the cavity 2, that is, the bottom surface 7a is designed to be 80 mm or more.

The magnetron 8 includes a vacuum tube container 19 having an anode and a cathode, a radiation fin 10 fixed to the outer periphery of the vacuum tube container 19 by press-fitting or the like, a magnet 11, and both the vacuum tube container 19 and the magnet 11 in the axial direction. The yoke 12 is sandwiched between the yoke 12 and the antenna unit 13 penetrating the yoke 12 and protruding from the vacuum tube container 19.

The antenna section 13 has an antenna cap 14a covered on the tip and an antenna cap 14a.
And a ceramic insulating cylinder 14b interposed between the vacuum cylinder 19 and the vacuum tube container 19.

Reference numeral 15 denotes a radiating antenna which is disposed around the antenna cap 14a and has a substantially donut shape in a front view and is made of a circular flat metal material such as aluminum so as not to contact the antenna cap 14a.

The distance between the antenna cap 14a and the radiating antenna 15 is designed to be approximately 2 mm so that no discharge occurs and the radio wave can be efficiently coupled. Also,
A sufficient distance is provided between the waveguide 7 and the radiation antenna 15 so that no discharge occurs.

Reference numeral 16 denotes a fixing plate provided with a through hole 17 having a diameter smaller than the inner circumference of the radiation antenna 15 at a substantially central portion, and formed of a mica plate for fixing the radiation antenna 15.

The diameter of the through hole 17 of the fixing plate 16 is substantially equal to the diameter of the antenna cap 14a of the magnetron 8, and the fixing plate 16 is attached so as to be pushed into the antenna cap 14a.

[0013] This is a radiation antenna 1 for repair.
When the diameter of the through hole 17 is larger than the diameter of the antenna 13 when the antenna 5 is removed and then re-installed, the antenna can be easily installed, but the distance between the radiating antenna 15 and the antenna cap 14a changes. This is because uneven heating may occur, or electric discharge may occur between the radiation antenna 15 and the side wall of the waveguide 7.

15a, 15b and 15c are radiation antennas 1
Ribs 16c, 16 provided at approximately 120 ° intervals around
Reference numerals d and 16e denote mounting holes provided in the fixing plate 16, and each of the ribs 15a, 15b, 15c
Through the mounting holes 16c, d, and e to fix the radiation antenna 15.

Reference numerals 16a and 16b denote ribs provided around the fixing plate 16, which penetrate through slits (not shown) provided at appropriate positions on the side wall of the waveguide 7 to fix the fixing plate 16 in the waveguide. , The radiation antenna 15 is arranged in the waveguide 7.

Numeral 18 denotes a plurality of vents provided on the side wall of the waveguide 7, and the inside of the waveguide becomes high in temperature during the heating operation. The vent 18 is provided so as to be parallel to the radiation antenna 15, and the vent 18 is not provided on the side wall of the waveguide 7 facing the radiation antenna 15.

That is, when the radiation antenna 15 is attached to the antenna cap 14a of the magnetron 8 and the vent 18 is viewed from outside the waveguide 7, the radiation antenna 1 is positioned at a predetermined position.
5 is not visible if it is mounted, and becomes visible if it is mounted at a shifted position, so that the mounting state can be easily confirmed.

In this configuration, during the heating operation, the antenna cap 14a of the magnetron 8 and the radiation antenna 1
5, an electric field is generated, and microwaves are emitted in a direction perpendicular to the electric field. Also, an electric field is generated between the radiation antenna 15 and the wall surface of the waveguide 7, and the microwave is radiated similarly.

The radiation antenna 15 floats in space without contacting anywhere, whereas the wall surface of the waveguide 7 is grounded, so that the electric field between the antenna cap 14a and the radiation antenna 15 causes The microwave between the radiation antenna 15 and the wall of the waveguide 7 is more radiated because the electric field between the antenna and the wall of the waveguide 7 is much stronger.

Therefore, microwaves are radiated only between the antenna cap 14a and the wall of the waveguide 7 in the related art. Therefore, the radiation area from which the microwaves are radiated becomes very large, the microwaves can be radiated in the cavity 2 in a shower shape, and the heating unevenness can be improved accordingly.

[0021]

However, since the above-mentioned radiation antenna 15 is fixed in parallel to the wall surface 2b of the cavity 2, the radiation radiated from the entire circumference of the radiation antenna 15 in the waveguide 7 is reduced. The wave is similarly reflected in the waveguide 7 and diffused into the cavity 2, but after the fixed position of the radiating antenna 15 is determined by design, the fixed position of the radiating antenna 15 is moved forward and backward. Since it cannot move, the heating unevenness cannot be improved.

The present invention solves such a problem.

[0023]

The microwave oven according to the present invention comprises:
A cavity for accommodating an object to be heated, a waveguide for propagating and supplying microwaves into the cavity, and an antenna fixed to a bottom surface of the waveguide facing the cavity and from the bottom surface into the waveguide. And a magnetron with
An antenna and a guide for the magnetron in the waveguide and
Antenna and guided wave of the magnetron separated from the waveguide
At the position where discharge does not occur with the tube, the magnetron antenna
And a flat radiation antenna fixed around the antenna so as to surround the antenna, and a part of the radiation antenna is bent toward the magnetron side and / or the cavity side.

[0024]

In other words, the microwave radiated from the radiation antenna into the cavity is inclined with respect to the wall surface of the cavity or partially bent, so that the direction of the microwave radiated therefrom is different from that of the other. The direction of the microwave incident from the waveguide into the cavity is also different because the direction is different from the direction of the radiation from the portion, and the microwave is complicatedly diffused into the cavity.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 2. Components having the same reference numerals as those already described have the same functions and will not be described.

FIG. 2 is not a longitudinal sectional view in the same direction as that of FIG. 6, but a horizontal sectional view of the waveguide 7 and the magnetron 8 in FIG.

Reference numeral 20 denotes a fixed plate formed of a mica plate having a through hole at a substantially central portion and fixed substantially parallel to the side wall 2b of the cavity 2, and has a surface 20a on the cavity 2 side and a magnetron 8 side. Face 20b is facing.

Reference numeral 21 denotes a flat radiating antenna fixed to the surface 20b of the fixing plate 20 on the magnetron 8 side.

Since the radiation antenna 21 is fixed to the fixing plate 20, it is fixed substantially parallel to the side wall 2b of the cavity 2.

The fixing method of the fixing plate 20 to the waveguide 7 is as follows.
The method of fixing the radiation antenna 15 to the fixing plate 20 is the same as that of the above-described conventional radiation antenna 15 and fixing plate 16.

Reference numeral 22 denotes a radiation antenna 21 and a cavity 2
An antenna bent portion provided on the left side as viewed from the side, and an arc portion extending from the outer periphery to a length of approximately 1/4 of the diameter in the center direction,
Angle α ° from surface 20a of fixed plate 20 (for example, approximately 30 °)
It is bent to the cavity 2 side.

In such a configuration, the microwave is applied to the antenna cap 14 a of the magnetron 8 and the radiation antenna 21.
And an electric field is generated between the radiation antenna 21 and the waveguide 7 to be radiated in the direction of the cavity 2. However, since the antenna bent part 22 is provided in a part of the radiation antenna 21,
The distance between the side wall 2b of the cavity 2 and the outer periphery of the radiation antenna 21 differs only in the bent portion 22 of the antenna.

Therefore, the cavity 2 of the radiation antenna
When the portion near the cavity 2 is radiated, it is easily propagated into the cavity 2 as it is, but in the portion away from the cavity 2, the direction of propagation is changed by the above-mentioned microwave and reflected inside the cavity 2 by reflecting on the wall surface of the waveguide 7. To be propagated.

Therefore, in the cavity 2, the microwave propagates in a complicated manner, so that the uneven propagation is eliminated, and the uneven heating is improved.

FIG. 3 shows actually cut beef meat for about 10 minutes.
The temperature of each part at the time of thawing at 200 W is determined by the case where the antenna bending part 22 is not provided in the radiation antenna 21 (that is, α
= 0 °) and a case where the angle α is 30 ° and the antenna bent portion 22 is provided, and the measurement results are shown separately.

Comparing the two temperature measurement results (a) and (b), the result of (a) without the antenna bent part 22 shows that the upper right and lower left corners have higher temperatures than the other parts. It is high and boiled, but antenna bent part 2
In the result of (b) in which 2 was provided, the boiling was not performed, and the temperature of each part was substantially equalized as compared with the result (a).

That is, from these results, the antenna bent portion 2
It can be seen that, when 2 is bent toward the cavity 2, uneven heating in the planar direction is improved.

The location where the antenna bent portion 22 of the radiation antenna 21 is provided is not limited to this, and may be provided anywhere on the periphery of the radiation antenna 21.

In addition to the embodiment shown in FIG. 2, the radiation antenna 21 is located on the right side as viewed from the cavity 2 as shown in FIG.
May be provided.

The radiating antenna 21 has the radiating antenna 21 attached to the surface 20b of the fixed plate 20 on the magnetron 8 side. Magnetron 8 from surface 20b
It is bent at an angle β ° to the side.

The relationship between the angle β ° and the output when heating 2 liters of water, and the relationship between the angle β ° and the output when heating 150 cc of sake into the bottle and heating for 76 seconds and the temperature difference between the upper and lower portions of the bottle. It is shown in the table below.

[0042]

[Table 1]

From Table 1, it can be seen that even if 2 liters of water is heated, the output does not change much. However, as the bending angle β of the bent portion 22 of the antenna is increased, the heating output to 150 cc of sake is increased. I understand. In other words, it can be seen that the heating of a light load is convenient for improving the output.
However, the heating unevenness in the vertical direction has not been significantly improved. Further, as shown in FIG. 5, the radiation antenna 2 shown in FIG.
Antenna bent portions 22a and 22b bent from the surface 20b of the fixed plate 20 to the angle β ° magnetron 8 side may also be provided on the left side of 1.

Further, as shown in FIG. 6 , the shape of the radiation antenna 21 obtained by combining FIGS. 2 and 4, that is, the arc on the left side of the radiation antenna 21 when viewed from the cavity 2 side is α ° from the fixed plate 20. An antenna bent portion 22c bent toward the cavity 2 and an antenna bent portion 2 bent at the right arc portion from the fixed plate 20 toward the β ° magnetron 8 side.
By providing 2d and providing each feature, it is possible to improve the output due to a light load and to improve the uneven heating in the planar direction.

The radiation antenna 21 is fixed to a surface 20b of the fixed plate 20 on the magnetron 8 side through a left antenna bent portion 22c in a slit 20c provided in a part near the outer periphery of the fixed plate 20.

In the embodiment shown in FIGS. 2 to 6 above, after the structural design of the microwave oven has been completed and the fixing position of the radiating antenna 22 has been determined, for example, the cavity 2 is provided for reinforcement.
Even if the shape of the cavity 2 is slightly changed and the pattern of the uneven heating in the cavity 2 is changed by adding a pusher or the like to the bottom wall of the antenna, only the bending angles α and β of the antenna bent portion 22 are adjusted. This is a very effective means that can respond and does not require significant changes.

[0047]

According to the present invention, a magnetron antenna is provided.
Between the radiating antenna and the radiating antenna and the waveguide wall
Since microwaves are radiated from the
The radiation area from which waves are radiated becomes very large, and the cavity
Microwaves can be radiated in the form of a shower inside, and by bending a part of the radiation antenna, the direction of microwave radiation from the radiation antenna is changed, thereby improving the unevenness of microwave propagation in the cavity and improving heating unevenness. Is what you do.

[Brief description of the drawings]

FIG. 1 is a sectional view of a microwave oven according to the present invention.

FIG. 2 is a diagram showing a cross section of a portion A in FIG. 1;

FIG. 3 is a diagram showing measured temperatures of each part when thawing thin meat is thawed in a case where an antenna bent portion is provided in a radiation antenna and in a case where the antenna bent portion is not provided.

FIG. 4 is a diagram showing another embodiment.

FIG. 5 is a diagram showing another embodiment.

FIG. 6 is a diagram showing another embodiment.

FIG. 7 is an enlarged sectional view showing a conventional structure of a portion A in FIG.

FIG. 8 is a front view of a conventional radiation antenna.

[Explanation of symbols]

 2 Cavity 7 Waveguide 8 Magnetron 13 Antenna 14a Antenna cap 20 Fixing plate 21 Radiation antenna 22, 22a, 22b Antenna bent part

Claims (1)

(57) [Claims] 1. A cavity for accommodating an object to be heated, a waveguide for propagating and supplying microwaves into the cavity,
Fixed to the bottom surface of the waveguide facing the cavity.
A magnetron having an antenna protruding from the bottom surface into the waveguide , and a magnetron within the waveguide and the magnetron.
Of the magnetron apart from the antenna and waveguide of the
At the position where the antenna and waveguide do not discharge,
Fixed around this antenna to surround the TRON antenna
Tabular in a radiating antenna, of the radiating antenna
A microwave oven wherein a part thereof is bent toward the magnetron side and / or the cavity side.