JPS6336956Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a microwave oven that feeds microwaves into a heating chamber through a waveguide.

(B) Prior Art In general, in a microwave oven, it is very important to uniformly heat food without uneven heating. Conventionally, various measures have been taken regarding this point, such as installing a stirrer to stir the microwaves in the heating chamber or a turntable to rotate the food, and installing a waveguide to guide the microwaves into the heating chamber. They put effort into the shape.

1 and 2 relate to the shape of such a waveguide. The waveguide 3 that guides the 2450MHz microwave from the magnetron 1 into the heating chamber 2 is shaped like a cross; The intersection C of each branch 4, 4...
Power feed ports 5, 5... are located at a predetermined distance from each other.
is provided, and microwaves are supplied into the heating chamber 2 from the power supply port. Furthermore, in the heating chamber 2, there is further arranged a stirrer 7 which is supported by a shaft 6 made of a material with small dielectric loss and which stirs the microwave.

Therefore, when conducting an experiment on uneven heating of food in such a microwave oven, water is poured onto the bottom surface 2a of the heating chamber 2.
5 beakers containing 240c.c. (water temperature 20℃) 8,8
When... are arranged as shown in Fig. 3 and heated for 2 minutes with a microwave output of 625 W, the water temperature in each beaker 8, 8... increases by 16.5°C, 17.6°C, 14.3°C, 15.4°C, and 18.6°C, respectively. From this value, the deviation rate P [=(maximum increase value - minimum increase value)/(average value of each improvement value)] is found to be 26.1%. The larger the value of this deviation rate P, the more uneven heating is, and the smaller the value, the less uneven heating is. In this case, the deviation rate P is 26.1
%, therefore, it can be seen that such microwave ovens have not yet been able to sufficiently eliminate heating unevenness.

(c) Purpose of the invention The purpose of the invention is to obtain a microwave oven that can sufficiently eliminate uneven heating.

(d) Structure of the invention In order to achieve the above object, the invention is constructed such that waveguides are formed in a radial manner and a power supply port for feeding microwaves into the heating chamber is provided at the intersection of the waveguides.

(e) Examples A microwave oven according to an embodiment of the present invention will be described below.

In FIGS. 4 and 5, the waveguide 11 that guides the 2450 MHz microwave from the magnetron 9 into the heating chamber 10 is formed in a radial shape, that is, in a cross shape, and the microwave is directed into the heating chamber at the intersection C of the waveguide 11. A power supply port 12 for supplying power into the power supply 10 is provided. In the heating chamber 10, a stirrer 14 is provided which is supported by a shaft 13 made of a material with small dielectric loss and which stirs the microwave, as in the conventional case. The above waveguide 1
The dimensions of each branch portion 11a to 11d of 1 are as follows: width w is 9
cm, the height h is 3 cm, and the branch parts 11a, 11
The length l ₁ of b and 11c is λg (wavelength of the microwave used), and the length l ₂ of the branch portion 11d is 22.5 cm. Furthermore,
The power supply port 12 is a square with a side of 9 cm (=ω).

To explain the propagation state of microwaves in such a configuration, the microwaves from magnetron 9 pass through waveguide 1.
1 and reaches the power feeding port 12. A part of the microwave is directly fed into the heating chamber 10 from the power feed port 12, but the rest further goes to each branch 11a, 11b, 11c having a length _l1 of λg. The microwaves that have proceeded to each of the branches 11a, 11b, and 11c are all reflected by the short-circuit surfaces of the branches 11a, 11b, and 11c, reach the power feed port 12 again, and are fed into the heating chamber 10. Here, the microwave from the branch 11b is in the same phase as the microwave directly fed from the branch 11d through the power feed port 12, and the microwave from the branch 11a,
The microwaves from 11c are in phase with each other, but the direction of the electric field is different from that of the directly fed microwaves.
It is shifted by 90 degrees. And each branch part 11a-11d
Microwaves supplied through the power supply port 12 are stirred by a stirrer 14 .

Therefore, in order to conduct an experiment on uneven heating of food, beakers 15, 15, .
When heated for 2 minutes at 625W, each beaker 15,15
The water temperatures of ... are 15.8℃, 15.7℃, 16.6℃, 16.2℃, respectively.
It will rise by 16.7℃. When the deviation rate P is calculated from these values, it is 6.2%, and in this case, the deviation rate P is significantly smaller than that of the conventional case, and it can therefore be seen that heating unevenness has been sufficiently eliminated.

(f) Effects of the invention As is clear from the above explanation, according to the invention, the waveguides are formed in a radial shape, and a power supply port for feeding microwaves into the heating chamber is provided at the intersection of the waveguides, thereby reducing uneven heating. You can get an extremely practical microwave oven.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional microwave oven, Figure 2 is a cross-sectional view taken along the line - - in Figure 1, Figure 3 is a plan view of the main parts of the same microwave oven to explain the experimental state, and Figure 4 is a booklet. FIG. 5 is a cross-sectional view taken along the line -- in FIG. 4, and FIG. 6 is a plan view of a main part of the microwave oven for explaining an experimental state of the same microwave oven. 11...Waveguide, 12...Power supply port.

Claims (1)

[Scope of utility model registration request] In a microwave oven that feeds microwaves from a microwave generating means into a heating chamber via a waveguide, the waveguides are formed in a radial shape, and a power supply for feeding microwaves into the heating chamber at an intersection thereof. A microwave oven characterized by having a mouth.