JPH0552636B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high-frequency heating device for high-frequency heating of an object to be heated, such as food, using radio waves.

Conventional technology Generally, the frequency band specifically approved for use in high-frequency heating equipment is the 2450 MHz band or 915 MHz band.
Although it varies somewhat depending on the country, such as the Hz band, it is limited to certain bands. This band is not subject to regulations under the Radio Law as long as safety is guaranteed. However, high frequency oscillators generally have harmonic components,
In the case of a high frequency oscillator such as a magnetron whose fundamental frequency is 2450MHz, 4900MHz, 7350MHz,
It has relatively large power components at 9800MHz, 12250MHz, etc. Since these harmonic components are subject to strict regulations under the Radio Law, various measures have been taken to reduce leakage sources. For example, a radio wave absorber such as ferrite is placed around the opening/closing door of the heating chamber to absorb high frequency waves leaking from the gap and convert them into heat. Since harmonics have shorter wavelengths than the fundamental wave, there is also a large leakage from the gaps between the tiny joints in the heating chamber, which is formed by bending and joining metal plates and forming a rectangular shape. At present, methods such as joining by seamless seam welding or by integrally drawing the entire heating chamber from metal were put into practical use.

Problems to be Solved by the Invention However, the configurations described above for reducing leakage radio waves from joints such as heating chambers require large-scale equipment during processing, and There were problems in that it was difficult to process and expensive, with limitations on the

The present invention solves these conventional problems, and can prevent leakage of high frequency waves from the heating chamber and waveguide that have joints with a simple configuration. The present invention provides an excellent high-frequency heating device that can improve strength.

Means for Solving the Problems The high-frequency heating device of the present invention includes a heating chamber filled with high-frequency waves, a waveguide, and a plurality of radio wave leakage paths that are perpendicular to the direction of radio wave propagation caused by the gaps between their mutual contact parts. A row of joint points formed by spot welding is arranged such that the joint points of each adjacent row are arranged in an interpolated manner.

Effect The high-frequency heating device of the present invention has the above-mentioned configuration, which lengthens the transmission path of radio waves leaking through the radio wave transmission path caused by the gap between the abutting portions of the metal flat plates, resulting in transmission loss. The radio wave is attenuated by increasing the angle of incidence of the radio wave and by reducing the angle of incidence of the radio wave that enters the gap.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

In FIG. 1, high-frequency electromagnetic waves oscillated by a high-frequency oscillator 1 are radiated to a waveguide 2 and a radio wave transmission path 3
and enters the heating chamber 4. The heating chamber 4 is formed by a top plate 5 formed by bending a metal flat plate, a rear plate 6, a bottom plate 7 and a front plate 8 which are bent integrally with left and right side plates, and are brought into contact with each other. A door 9 that can be opened and closed is provided on the front side of the heating chamber 4, facing the front plate 8.
Leakage of radio waves from the heating chamber 4 is prevented by a check groove 10 provided around the door 9 and a radio wave absorber 11.

Here, the means for joining the abutting portions of the top plate 5 and the rear plate 6 will be explained with reference to FIG. 2 as an example. The top plate 5 and the rear plate 6 are in contact with each other by a rear plate flange 6a,
The joints are spot welded by the joint rows 13a and 13b, and the joint rows 13a and 13b are arranged in an interpolated manner (arranged in a staggered manner).

In the above configuration, the intensity S of the radio waves leaking out of the heating chamber through the transmission path created by the gap between the contact parts is determined by the contact part length A, the gap t, and the incident angle θ,
Since there is a relationship S t/A・cos θ, the radio wave incident on the gap t from inside the heating chamber 4 passes through the junction interval B of the junction array 13a, and further passes through the junction interval B of the junction array 13b. It leaks through the point interval D. Therefore, equivalently, it passes through the interval B' formed by both the junction rows 13a and 13b. Furthermore, the incident angle θ of the radio waves becomes smaller than 90 degrees, and the radio wave leakage path becomes longer. Furthermore, since the rows of joint points are arranged at intervals of C, the joints of the joint flanges are not linear but planar, and the gap is small, so that radio waves can be shielded sufficiently.

Furthermore, the radio waves leaking from the junction gap are affected by the junction spacing, and the maximum radiation occurs when the junction spacing is 1/2 of the wavelength. Therefore, with a configuration in which the junction gap is equivalently reduced, harmonics (with short wavelengths) can be sufficiently shielded. Note that the joining flange 2a of the waveguide 2 and the rear plate 6
The joining structure is also the same as the joining structure between the top plate 5 and the rear plate flange 6a of the rear plate 6 described above.

Effects of the Invention As described above, the high frequency heating device of the present invention provides the following effects.

(1) Since the joints between the waveguide and the heating chamber are arranged in multiple rows and the joints are interpolated, the radio wave leakage path is not long and the transmission loss can be increased, and the angle of incidence at the joint can be reduced. , it is possible to significantly improve the radio wave shielding ability.

(2) The strength of the joint can be improved with a simple configuration in which the joint points are arranged in a planar manner.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view of a high-frequency heating device according to an embodiment of the present invention, and FIG. 2 is a perspective view of a cross-section of the main part of FIG. 1. DESCRIPTION OF SYMBOLS 1... High frequency oscillator, 2... Waveguide, 4... Heating chamber, 5... Top plate, 6... Rear plate, 6a... Rear plate flange, 13a, 13b... Junction point array.

Claims (1)

[Claims] 1 A heating chamber formed by combining a plurality of metal flat plates into a substantially rectangular parallelepiped, and a waveguide provided opposite to the heating chamber wall and formed by bending the metal flat plate, the heating chamber and the waveguide and A high-frequency system with a structure in which a plurality of rows of joint points are formed by spot welding orthogonal to the radio wave propagation direction of the radio wave leakage path caused by the contact between these mutual contact parts, and the joint points of each adjacent row are arranged in an interpolated manner. heating device.