JPS62110287A - Microwave oven - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a microwave oven having not only a microwave oven function but also a grill function and an oven function for heating cooked food using a heater.

[Background of the invention]

Microwave ovens can heat food from within, so they can uniformly and rapidly heat the entire material, making it less likely that uneven cooking will occur, making it particularly useful for defrosting frozen foods. Further, simmer. In order to add variety to dishes by combining them with various cooking methods such as grilling, models that have not only a microwave function but also a grill function that uses a heater or an oven function are becoming widespread.

Conventionally, a full-flex heating element has been used as a heater, but if organic dirt adheres to it after cooking, it will be affected by corrosive action, so it was necessary to wipe off the dirt from time to time. Also, for the same reason, it could not be used for the purpose of contacting food.

[Purpose of the invention]

The purpose of the present invention is to use conductive ceramics that have excellent high-temperature durability such as corrosion resistance and oxidation resistance, so that they do not require maintenance for a long time and can be self-cleaned or burnt by contacting with food. The purpose of the present invention is to provide a microwave oven equipped with a heater.

[Summary of the invention]

The microwave oven of the present invention is characterized in that the heater used for the grill function or the oven function is made of conductive ceramics whose temperature increases when energized.

The conductive ceramic may be a composite sintered body of at least one of silicon carbide and aluminum oxide and at least one of zirconium boride, titanium boride, hafnium boride, and tantalum boride, or a composite sintered body of at least one of silicon carbide and aluminum oxide, or a composite sintered body of silicon nitride and titanium nitride. It is preferable to use a composite sintered body as the main body.

Such a composite sintered body has electrical conductivity comparable to that of metal and exhibits high-temperature oxidation resistance superior to that of metal, so it is suitable for direct heating type ignition heaters that can heat rapidly.

Furthermore, as a result of various studies on the properties of such a composite sintered body, it was experimentally confirmed that it has excellent corrosion resistance at high temperatures and has very little property deterioration due to the adhesion of organic matter. In addition, if a part of the object to be heated adheres to the object, the heater made of such a composite sintered body burns out the adhered material without adversely affecting the properties by raising the temperature to a higher temperature than the sintering temperature. It has been found that so-called self-cleaning is possible. The present invention has been made based on this new knowledge.

The composite sintered body used as the heater of the microwave oven of the present invention has higher strength even at high temperatures than the metal used for the heater, so it can also be used by being directly pressed against an object to be heated. In addition, since it has a resistivity as low as that of metal, electrical discharge machining is possible and the sintered body can be cut into complex shapes. Depending on the purpose, heaters with complex shapes can also be made. Zirconium boride and titanium boride make the sintered body highly conductive.

This is because hafnium boride, tantalum boride, or titanium nitride have conductivity equivalent to that of metal.

Because the melting point of these compounds is high and the heat resistance of silicon carbide, aluminum oxide and silicon nitride is high.

The composite sintered body also has excellent heat resistance. The composite sintered body has high strength and excellent oxidation resistance even at high temperatures because silicon carbide, aluminum 9 oxide, and silicon nitride protect the combined boride component and titanium nitride. The excellent corrosion resistance resulting from the present invention is also believed to be due to the same reason.

The composite sintered body used in the present invention can be manufactured by mixing and molding raw material powders and then performing pressureless sintering or hot press sintering. At this time, by adjusting the blending ratio of high-resistance silicon carbide or aluminum oxide and low-resistance boride, or the blending ratio of silicon nitride and titanium nitride, it is possible to obtain a sintered body with a resistivity suitable for the desired heater. Furthermore, during sintering, it is desirable to add an auxiliary agent to promote sintering.

[Embodiments of the invention]

The present invention will be explained below with reference to Examples.

Example 1 A mixed powder of 48.5% by weight of black silicon carbide (Sin) powder, 1.0% by weight of aluminum oxide (Aα10.) powder, and 50.5% by weight of zirconium boride (ZrBz) powder was added to 100 parts by weight. To the mixture, 20 portions of a xylene diluted molding binder (silicone resin) were added and mixed. After molding the mixed powder at a pressure of LOOQ kg/ad, it was sintered using a vacuum hot press device in a vacuum of 10-1 to 10-' Torr at a pressure of 300 kg/ad and a temperature of 2050°C to form a diameter of 130 m. .

A sintered body with a thickness of 1 m was obtained. Next, a heater 1 having the shape shown in FIG. 1 was cut out from this sintered body by laser processing. Part 11 of the heater was metallized with nickel, and a lead wire was connected thereto. This heater was incorporated into a microwave oven to produce a microwave oven having both a microwave oven function and a grill function as shown in FIG. In FIG. 2, L is a heater, 2 is a turntable on which an object to be heated is placed, 3 is a high frequency source, 4 is a cabinet, and 5 is a front door.

The capacity of the heater used was 1.2 for 100V AC.
It was KW. After heating this heater to 800℃ and cooking meat etc. for a total of 100 hours, turn the heater to 1000℃.
The temperature was raised to ℃. Through this operation, the deposits on the heater were completely carbonized and removed from the heater for self-cleaning. Moreover, no change in characteristics occurred in the heater.8 Example 2 Heater 1 made of a composite sintered body produced in the same manner as in Example 1 was incorporated into a microwave oven, and a microwave oven with both microwave oven function and grill function was created. Created. At this time, with this microwave oven, which is equipped with a mechanism to slide heater 1 up and down, the meat is first cooked using the microwave function, and then the heater is heated to 800°C to create a tingling burn on the entire surface of the meat. I set my eyes on it.

Next, the heater temperature is set to 600°C, and the heater is lowered.
By pressing it against the surface of the meat, a mesh-like brown mark was created on the surface.

After repeating the operation of pressing the heater against the surface of the meat to brown it 10 times, self-cleaning was performed by raising the temperature of the heater to 1000°C.

A cycle of 10 browning operations and 1 self-cleaning cycle was repeated 100 times, but no change occurred in the characteristics of the heater.

Example 3 51% by weight of SiC powder, 1% by weight of AQ, O1 powder, and 48% by weight of titanium boride (TiB) powder were mixed, and the same procedure as in Example 1 was carried out to form a powder with a diameter of 130a11. A sintered body having a thickness of II was obtained. Next, a heater 6 having the shape shown in FIG. 3 was cut out from this sintered body by laser processing. Another heater of the same shape was fabricated using the same method, and these two heaters were placed above and below the microwave oven to fabricate a microwave oven that combines microwave oven function, grill function, and oven function.

Apart from this, SiC powder Song 28.4% by weight, AQ201
Mix 0.6% heavy European powder, 35% by weight hafnium boride (HfB) powder, and 36% by weight tantalum boride (TaB) powder, and prepare two heaters as shown in Figure 3 in the same manner as above. In the same manner as described in Section 6, a microwave oven having both a grill function and an oven function was manufactured by arranging these two heaters one above the other.

The capacity of the resulting heater was IKW for AC LOOV per iar. These microwave ovens were used for cooking for 100 hours with the grill function at IKW output for only the upper heater, and then for 100 hours at the upper and lower heater outputs of 0.5 KW each for the oven function. The dirt attached to the heater during this process could be self-cleaned by raising the temperature of the heater to 3+ooo°C. After self-cleaning, the characteristics of all heaters were the same as their initial characteristics.

Also, among these heaters, 60 heaters are placed on top.
The operation of heating it to 0°C, sliding it, bringing it into contact with the surface of the food, and browning it was repeated 1000 times, but no abnormality was observed in the characteristics of the heater.6 Example 4 AQ, ○, Powder 49.1 Heavy European%, magnesium oxide (
MgO) powder 0.5% by weight and ZrB, powder 50.4%
Molding binder (5% PV
A composition obtained by adding and mixing 20 parts by weight of A aqueous solution) was
It was molded into a disk shape with a diameter of 200 mm and a thickness of 2 m at a pressure of ookg/ad. Cut the molded body using a laser cutting machine,
1 in a furnace with a nitrogen-hydrogen mixed gas atmosphere at a low gas pressure of 1.
The heater 1 having the shape shown in FIG. 1 was manufactured by sintering at a temperature of 700°C. A heater 6 having the shape shown in FIG. 3 was also produced by a similar method.

A microwave oven having both a grill function and an oven function was manufactured by arranging heater 1 at 1- and heater 6 at the bottom. A mechanism to slide this special heater 1 up and down was also installed. Heater 1. The capacity of both heaters 6 was 1.2 KW for AC 10 OV.

Upper heater only i, 2KW grill function for 10 hours (-
After cooking for 10 hours using the oven function of each 0.6 KW lower heater, the operation of browning the meat on a grid was performed 10 times. Next, self-cleaning was performed at 900°C. Even after repeating this cycle 10 times, the characteristics of the heater remained unchanged from the initial state.

Example 5 Silicon nitride (Si, N,) powder 36.4% by weight, yttrium oxide (yt03) powder 2.2% by weight, AQ
, 03 powder 5.3% by weight, aluminum nitride (/11.
To 100 parts of a mixed powder of 2.2% by weight of N) powder and 53.9% by weight of titanium nitride (T i N) powder, 10 parts of a molding binder (5% PVA aqueous solution) were added and mixed. After the mixed powder was molded at a pressure of 1000 kg/d, it was sintered using a hot press machine in N2 gas at 1 atm at a pressure of 300 kg/cd and a temperature of 1750°C for 1 hour, and the sintered body was subjected to electrical discharge machining. A heater having the shape shown in FIG. 1 was cut out.

As in Examples 1 and 2, a microwave oven also equipped with a grill function was manufactured using this heater. The performance of this heater is
It was the same as in Example 1.2.

Example 6 In the same manner as in Example 1, S with a diameter of 60ww and a thickness of 1mm+ was prepared.
A composite sintered body mainly composed of iC and ZrB was obtained.

A heater 7 having the shape shown in FIG. 4 was cut out from this sintered body by electrical discharge machining. In the same manner, a heater 8 having the shape shown in FIG. 5 was manufactured.

The top heater of the microwave oven, which also has an oven function, can be replaced by inserting it, and a mechanism to slide it up and down is attached.

Bread was baked in this microwave oven using the oven function, and then the upper heater was brought into contact with the surface of the bread as the heater 7 described above, and browned in the shape of the heater shown in FIG. 4. Further, the upper heater was used as the heater 8, and was brought into contact with the surface of another bread to brown the bread in the shape of the heater shown in FIG.

No change in characteristics was observed in any of the heaters even after repeated use 500 times, and it was possible to self-clean by raising the temperature to 1000°C. In other words, it was found that by manufacturing heaters of various shapes and using them interchangeably, a microwave oven could be given the ability to brown the surface of a single food product in various shapes.

〔Effect of the invention〕

As mentioned above, according to the present invention, corrosion resistance.

By using conductive ceramics with excellent heat resistance as a heater, we can obtain a microwave oven with stable characteristics, self-cleaning, and the ability to brown food by touching it with the heater, as well as grilling and oven functions. be able to. Note that this effect is not limited to the above-mentioned embodiment, but can be similarly obtained with the combination of compositions shown in the claims and with heaters of other shapes. Furthermore, the above-mentioned heater can of course be used not only for two microwave ovens but also for a single oven appliance.

[Brief explanation of drawings]

Figures 1, 3, 4, and 5 are diagrams showing the shape of a heater manufactured in an example of the present invention, and Figure 2 is a diagram showing the structure of a microwave oven manufactured in an example of the present invention. It is a structural diagram. 1... Heater, 11... Lead wire connection part, 2...
Turntable, 3... High frequency source, 4... Cabinet, 5
...Front door. 6... Heater, 7... Heater, 8... Heater.

Claims (1)

[Claims] 1. A microwave oven having both a microwave oven function and a grill function and/or an oven function, characterized in that the heater is made of conductive ceramics. 2. Claim 1, wherein the conductive ceramic is a composite mainly consisting of at least one of silicon carbide and aluminum oxide and at least one of zirconium boride, titanium boride, hafnium boride, and tantalum boride. A microwave oven characterized by being made of a sintered body. 3. The microwave oven according to claim 1, wherein the conductive ceramic is made of a composite sintered body mainly composed of silicon nitride and titanium nitride. 4. A microwave oven according to any one of claims 1 to 3, characterized by having a mechanism for bringing a heater into contact with a cooked product.