JPH0743997Y2 - High frequency heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a high-frequency heating device such as a microwave oven.

(B) Conventional Technique In a conventional microwave oven, a heating means (sheath heater or ribbon heater) by resistance heating is provided inside the heating chamber in order to brown the food to be cooked.

FIG. 8 is a sectional view showing an example of the conventional heating means, 1 is a sheath heater, 2 is a heat insulating sheet, 3 is a case upper plate, 4 is a case lower plate, and the sheath heater 1 is a case lower plate. Food is heated through a hole 5 formed in the food product 4.

(C) Problems to be Solved by the Invention However, in such a conventional heating means,
It is difficult to evenly distribute the heat radiated from the heater in a plane, and the unevenness in the amount of heat radiated causes unevenness in the burned object (food). Further, there is a problem that it takes time to brown the object to be heated.

This invention was made in consideration of such circumstances,
(EN) A high-frequency heating device capable of efficiently forming a uniform brown mark by heating food by using a heating means by resistance heating and a microwave absorption heating element in combination.

(D) Means for Solving the Problem This invention relates to a high-frequency heating device having a microwave generator for irradiating microwaves, and a flat plate made of a material that generates heat by irradiating microwaves, and the flat plate being in close contact with the flat plate. A heating element consisting of a meandering sheathed heater is provided, and the heat generated from the flat plate is superposed on the heat generated from the flat plate by the irradiation of microwaves from the microwave generator while the sheathed heater is energized. The present invention provides a high-frequency heating device characterized by supplying to a heating object.

The sheathed heater may be sandwiched from both sides by a flat plate made of a material that generates heat when irradiated with microwaves.

For materials that generate heat when irradiated with microwaves,
For example, a ceramic molded body containing about 85% SiC is used. Further, the sheath heater is constructed by inserting a nichrome wire into the sheath (metal pipe) and insulating both with a heat-resistant insulator such as magnesium oxide powder.

(E) Action When a flat plate is irradiated with microwaves, the flat plate generates heat, and the sheathed heater provided on the flat plate also generates heat due to energization. Is uniformly distributed to the food, and the food is uniformly browned, and the efficiency of browning is improved.

(F) Embodiment Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. This does not limit the invention.

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a bottom view of FIG. In these figures, 11 is a sheathed heater that meanders in a plane.
Is a metal pipe 11a and a nichrome wire 1 inserted inside it.
Magnesium oxide powder 11c filled in 1b and pipe 11a
It consists of Reference numeral 12 is a flat plate made of a material that generates heat when irradiated with microwaves. In this embodiment, the flat plate is made of a ceramic molded body containing about 85% of SiC and has a meandering sheathed heater 11.
Are arranged so as to fill the gap. Reference numeral 13 denotes a plate for fixing the heating element 12, which is made of the same material as the flat plate 12 and is bonded to the flat plate 12.

In such a configuration, the heating element is irradiated with microwaves from a magnetron of a microwave oven, and when a current is applied to the sheath heater, the flat plate 12, the plate 13, and the sheath heater 11 generate heat, whereby both of them are heated. The heat generation temperature is made uniform in a plane, and the heat radiation surface (the lower surface of the flat plate 12 in FIG. 1) has a uniform temperature distribution of about 600 to 800 ° C.
Therefore, when the food is heated by such a uniformized heat radiating surface, even browning is efficiently formed on the food.

FIG. 3 is a sectional view showing another embodiment of the present invention.
Is a sheathed heater that meanders in a plane, 22 is a flat plate that is arranged so as to fill the gap of the sheathed heater 21, and the flat plate 22 contains a material that generates heat when irradiated with microwaves, such as approximately 85% SiC. Formed by a ceramic. Reference numeral 23 denotes a plate that supports the flat plate 22, and the plate 23 is made of a material that transmits microwaves, for example, cordierite. In this case, since the heat generated by the sheath heater 21 and the flat plate 22 is thermally insulated by the plate 23, the heat is efficiently dissipated from the radiation surface (lower surface). In addition, the heat of the flat plate 22 is to generate high-speed heat,
A thinner one is preferable, and a thickness of 0.1 to 3 mm is preferable. Then, the heat generated by the sheath heater 21 and the flat plate 22 forms a uniform heat radiation surface, whereby the food to be heated has a uniform browning.

FIG. 4 is a sectional view showing still another embodiment of the present invention, which is a material that absorbs microwaves to generate heat, such as SiC85.
A sheathed heater 31 that meanders in a plane is sandwiched between upper and lower surfaces by flat plates 32 and 33 formed by compacting and sintering a ceramic containing 100% by weight. Note that the flat plate 33 may be replaced with a cordierite molded body having a small thermal conductivity, for example. In this case, since the microwave penetrates the cordierite molded body, the sheathed heater 31 and the flat plate 32 preferentially generate heat only on one of the heat radiation surfaces. When the sheathed heater 31 and the flat plates 32 and 33 are integrated, the surface of the sheathed heater 31 is irradiated or coated with an adhesive ceramic frit and is fused and integrated with the flat plates 32 and 33 at a high temperature. It is preferable.

FIG. 5 is a cross-sectional view showing still another embodiment of the present invention, in which 41 is a sheathed heater that meanders in a plane, 42 is a sheathed heater 41 inserted in a press-molding die frame, and nitriding containing 85% SiC. It is made by filling ceramic compounding raw materials such as silicon and a binder, press-molding, and then sintering and integrating them. Also in this embodiment, the same effect as the above embodiment can be obtained.

In any of the above embodiments, it is possible to integrally form the sheathed heater and the flat plate, and in this case, even if the bonding portion between the sheathed heater and the ceramic material creates a space due to a difference in thermal expansion. Although there is no problem, if it is desired to completely bond the ceramics, it is preferable that the sheathed heater surface is subjected to pretreatment by irradiation with a ceramic having good adhesiveness or coating, followed by molding and sintering.

FIG. 6 is a structural explanatory view of the microwave oven for comparing the effect of the embodiment shown in FIG. 1 with the conventional example, and the heating element H is installed on the ceiling of the heating chamber R. When the temperature distribution was measured with respect to the horizontal distance 20 mm below the heat radiation surface of the heating element H thus installed, the result was as shown in FIG. Curve (a) shows that the heating element H is according to the embodiment shown in FIG.
The curve (b) is based on the conventional example. For the sheath heater, use 800W and the microwave output is 500W.
And The temperature distribution was measured 3 minutes after the start of energization of the sheath heater and magnetron. FIG. 7 shows that the temperature distribution of the heating element according to the present invention is much more uniform than the conventional example.

(G) Effect of the Invention According to this invention, it is possible to uniformly and efficiently form browns on food in a high-frequency heating device such as a microwave oven.

[Brief description of drawings]

1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a bottom view of FIG. 1, FIGS. 3 to 5 are sectional views showing another embodiment of the present invention, and FIG. 1 is an explanatory view showing the situation of temperature distribution measurement of the embodiment shown in FIG. 1, FIG. 7 is a graph showing the temperature distribution of the heat radiation surface of the embodiment shown in FIG. It is sectional drawing which shows an example. 11 …… Sheath heater, 12 …… Flat plate, 13 …… Plate,
11a …… Metal pipe, 11b …… Nichrome wire, 11c …… Insulator.

Claims (1)

[Scope of utility model registration request] 1. A high-frequency heating apparatus having a microwave generator for irradiating microwaves, comprising a flat plate made of a material that generates heat when irradiated with microwaves, and a sheathed heater that meanders in close contact with the flat plate. A heating element is provided, and the heat generated from the sheath heater is superimposed on the heat generated from the flat plate by the irradiation of microwaves from the microwave generator while the sheath heater is energized, and the heat is supplied to the object to be heated. High frequency heating device.