JPS6355199B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an improved high frequency heating device with respect to uniform heating.

As uniform heating means for high-frequency heating devices, there are known methods such as a stirrer that diffusely reflects high-frequency waves, a rotating antenna that emits high-frequency waves, a turntable that rotates the object to be heated, and a method of providing a large number of high-frequency supply ports on the peripheral wall of the heating chamber. . In any case, through numerous cut-and-try experiments, the heating unevenness has been reduced to the extent that it can be put to practical use, but in many cases the performance still cannot be said to be sufficient.

The present invention provides a high-frequency heating device with extremely low heating unevenness through a small number of confirmation experiments by combining a slot antenna array (slot array antenna) consisting of a plurality of slots having a specific dimensional relationship with a turntable. With the goal.

An embodiment of the high frequency heating device of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of essential parts showing an embodiment of the high-frequency heating device of the present invention. 1 is a high frequency oscillator that generates high frequency energy; 2 is a high frequency oscillator 1
This is a waveguide that connects the heating chamber 3 to the heating chamber 3. The heating chamber 3 and the waveguide 2 are formed from metal plates. A turntable 5 is provided at the lower part of the heating chamber 3 on which a heated object 4 such as food is placed and rotated. In the part where the waveguide 2 is connected to the heating chamber 3, the slots 6 and 7 are located at almost the same position, and the high frequency energy can be efficiently radiated from both slots by λg/2±λg/4 (λg: At the interval A1 (internal wavelength in the waveguide 2), the general high-frequency heating power is 2000 ~
2 with slot widths B1 and B2 of λg/4 or less up to λg/16 as the practical minimum range that can prevent sparks and abnormal heating near the slot for 400W.
A slot antenna row (slot array antenna) consisting of two slots 6 and 7 is provided. In particular, in the case of a large heating chamber 3, as shown in FIG. A slot antenna array consisting of three slots 6, 7, 8 may also be provided. Among the slots 6, 7, and 8, the number of slots is selected so that the slot 6 provided at the tip of the waveguide 2 is close to the center line 9 of the upper surface of the heating chamber 3 in the left-right direction with respect to the drawing.

As shown in the top view showing the top surface of the heating chamber 3 in FIG.
It is necessary that the slot 6 provided at the tip of the waveguide 2 be close to the center line 9 of the upper surface of the heating chamber 3 in the left-right direction, but the positional relationship with the center 10 of the upper surface of the heating chamber 3 is determined by appropriate experiments. . It has been experimentally confirmed that even if the tip of the waveguide 2 is mounted obliquely so as to be far away from the center 10 as shown in FIG. 3, heating unevenness is extremely small.

According to the above configuration, the temperature distribution of the heated object 4 as shown in FIG.
It is possible to raise the temperature to the same level as , and there is little variation in the temperature rise value depending on the position. In the general turntable system, the temperature rise value near the center is considerably lower than ΔTmean, as indicated by the dotted line 12, and the temperature rise value also varies greatly depending on the position.

In order to apply the above configuration to a 2450 MHz high frequency heating device, a waveguide with λg/2 of 95 mm is installed in a heating chamber of width 340 x depth 350 x height 250 mm, and the interval A1 between the two slots is set to 92 mm (approximately λg/2). 2) If the slot widths B1 and B2 are both 19 mm (λg/10), the average temperature rise value for all 37 points in a multi-point water load with 37 water loads of diameter 30 x height 12 mm arranged in a hexagonal shape is The ratio of the seven average temperature rise values near the center to △Tmean is
1.0, indicating a flat temperature distribution.

As described above, according to the present invention, by combining a slot antenna array having a specific dimensional relationship with a turntable, it is possible to provide a high frequency heating device with extremely little heating unevenness.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the main part of a high-frequency heating device according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of the same main part showing another embodiment of the present invention, and FIG. FIG. 4 is a top view showing the arrangement of the antenna arrays, and is a comparative diagram comparing the temperature rise distribution of the object to be heated by the high-frequency heating device of the present invention with that of a general turntable method. 1... High frequency oscillator, 2... Waveguide, 3... Heating chamber, 4... Heated object, 5... Turntable,
6, 7, 8...slot.

Claims (1)

[Scope of Claims] 1. A high-frequency oscillator that generates high-frequency energy, a waveguide that connects the high-frequency oscillator to a heating chamber, and a turntable for placing a heated object provided in the heating chamber, and the above-mentioned The part where the waveguide is coupled to the heating chamber has a slot width B1, B2, B3 of λg/4 or less up to λg/16 for each interval A1 and A2 of λg/2±λg/4 (λg: wavelength in the tube). A high-frequency heating device characterized by being provided with a slot antenna array consisting of a plurality of slots.