JP2567415Y2 - Microwave heating equipment - 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 heating apparatus for heating an object to be heated by microwaves in an oven while conveying the object to be heated by a belt conveyor.

[0002]

2. Description of the Related Art In a microwave heating apparatus of this type, an entrance and exit of an object to be heated must be opened in an oven for heating while being conveyed. Means for prevention must be provided. Conventionally, as a means for preventing this kind of microwave radio wave leakage, a metal shutter is provided at the entrance and exit of the object to be heated in the oven, and the shutter is opened only when the object to be heated enters and exits. There are a configuration in which the supply is stopped, and a configuration in which a radio wave absorber (water, ferrite, or the like) is arranged at the entrance and exit of the object to be heated to absorb leaked radio waves.
In addition, as shown in FIG.
A configuration has been adopted in which a plurality of bar-shaped chokes having a length of (λ: free space wavelength) are arranged on the upper surface of the inner wall of the radio wave leakage prevention unit at a pitch of λ / 4. In FIG. 4, 1 is a microwave oscillator, 2
Is a waveguide, 3 is an oven, 5 is a conveyor belt, and 21 is a bar-shaped choke. In such a configuration, the power oscillated from the microwave oscillator 1 passes through the waveguide 2 and passes through the oven 3
The object to be heated inside (not shown) is heated, and a part of the object leaks from the entrance and exit. Therefore, the arrangement of the bar-shaped choke 21 eliminates the microwave leakage radio wave. Was limited to λ / 4.

[0003]

In the conventional shutter system, the transport of the object to be heated is intermittent, and in order to transport the object continuously, the shutter must be opened to prevent leakage of electric waves. However, in the absorber method, if the opening height of the entrance and exit of the oven is increased according to the size of the object to be heated, the radio wave absorber must be enlarged, the device becomes large, and the absorption of the radio wave absorber There is a disadvantage that the loss of microwave power is increased. Further, the bar-shaped choke method has a disadvantage that the effect of preventing leakage is not provided unless the opening height of the entrance and exit of the oven is less than λ / 4 of the free space wavelength of the leaked radio wave. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a device capable of effectively preventing microwave leakage even when an opening height of an entrance and exit of an oven is λ / 4 or more.

[0004]

The microwave heating apparatus according to the present invention comprises a plurality of L-shaped chokes arranged above and below the entrance as means for preventing microwaves from leaking from the entrance of the object to be heated in the oven. It is what it was.

[0005]

FIG. 1 shows an overall schematic configuration of an embodiment of the present invention. In the figure, 1, 2, 3, and 5 indicate the same or corresponding parts as those in FIG. 4, 6 is a driving roller for applying a conveying force to the conveying belt 5 in the direction of arrow A, and 7 is a conveying belt 5
Tension rollers 8 and 9 are microwave leakage prevention units installed on the entrance side and exit side of the object to be heated in the oven 3.

FIG. 2 shows an example of the configuration of the microwave leakage prevention unit of the present invention. In the figure, 10 is a metallic box, 11
Is an L-shaped choke having a height of λ / 4 of the free space wavelength of the microwave and a lateral dimension of λ / 8, and a plurality of L-shaped chokes arranged at λ / 8 intervals in the longitudinal direction. FIG. 3 shows the arrangement of the L-shaped choke 11 as viewed from the direction of arrow B in FIG. The choke 11 is provided with a slit portion whose vertical dimension is narrow every λ / 8, and a space distance λ / 8 between both ends of the choke 11 and the side wall of the box 10.
And the slit portions 12 of the adjacent L-shaped chokes 11 were shifted by λ / 16 at a time. Also, the upper and lower opposing L
The slits are also set to λ / 16
It is attached by shifting by one.

[0007] When a plurality of L-shaped chokes are attached to the upper and lower surfaces of the box 10 and the radio wave leakage preventing portions 8 and 9 are arranged at the entrance and exit of the oven 3, microwave leakage from the inside of the oven 3 to the outside is performed. The phase difference between the radio wave and the reflected wave from the L-shaped choke 11 above and below the entrance and exit of the unheated object is λ.
/ 2 and cancel each other, and even if the opening height of the entrance is λ / 4 or more, it is possible to effectively prevent radio wave leakage. Although the opening height of the oven was conventionally λ / 4 or less, the opening height can be increased to about λ / 3 by using an L-shaped choke. According to the practice of the present invention, the conventional opening height is H = 25 m in a microwave heating apparatus having a microwave oscillation frequency of f = 2450 MHz.
It has been confirmed that even when the height of the aperture is increased to H = 40 mm, the radio wave leakage falls within a reference value.

[0008]

[Effects of the Invention] As described above, according to the present invention,
By arranging a plurality of L-shaped chokes above and below the entrance, respectively, it is possible to effectively prevent leaked radio waves even when the opening height of the entrance is λ / 4 or more, and the practical effect is great.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the overall schematic configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a configuration of an example of a microwave leakage prevention unit according to the present invention;

FIG. 3 is a view showing an arrangement state of an L-shaped choke in the microwave leakage prevention unit of FIG. 2;

FIG. 4 is an explanatory view of a microwave heating device using a conventional bar-shaped choke.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microwave oscillator 2 Waveguide 3 Oven 5 Conveyor belt 6 Driving roller 7 Tension roller 8, 9 Radio wave leakage prevention part 10 Case 11 L-shaped choke 12 Slit part

Claims (1)

(57) [Scope of request for utility model registration] 1. A microwave heating apparatus for performing heating treatment by microwaves in an oven while conveying an object to be heated by a belt conveyor, wherein a plurality of L-shaped chokes are arranged at entrances and exits of the object to be heated. Microwave heating device.