JP2513829B2 - High frequency cooking device with heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a housing in which a glass tube heater is provided in a penetrating manner, with a heater having an improved mounting structure of the glass tube heater. High frequency heating and cooking device.

(Prior Art) Conventionally, as a high-frequency cooking apparatus with a heater of this type, there is, for example, a structure shown in Japanese Utility Model Laid-Open No. 64-5397. As shown in FIG. 6, this product is formed on the side wall 2 of the heating and cooking chamber 1 so as to project the heater penetrating cylinder portion 3 inward, and the glass tube heater 4 is penetrated through the heater penetrating cylinder portion 3. The support plate 5 is used for fixing.

(Problems to be Solved by the Invention) In the above-described conventional high-frequency heating cooking device with a heater, since the heater holding tubular portion 3 is configured to project inside the heating cooking chamber 1, the tip of the heater penetrating tubular portion 4 is formed. The electric field of the microwave generated by the magnetron (not shown) is likely to be concentrated on the periphery, so that the microwave is generated by the glass tube heater 4
The amount that leaks out through the inside increases. In addition, since both sides of the glass tube heater 4 are covered with the heater penetrating cylinder portion 3 in the heating / cooking chamber 1, the heating area of the glass tube heater 4 is narrowed by that amount, and the heating efficiency is reduced. There is also. Further, since the glass tube heater 4 is attached so as to come into contact with the inner surface of the heater penetrating cylinder portion 3, the glass tube heater 4 strongly hits the heater penetrating cylinder portion 3 during assembly, or is damaged during transportation. There is a possibility that the glass tube heater 4 may interfere with the heater penetrating cylinder portion 3 due to the vibrations such as the above and may be damaged.

The present invention has been made in consideration of such circumstances, and therefore an object thereof is to be able to sufficiently enhance the microwave leakage prevention effect and to expand the heat generation region of the glass tube heater.
Moreover, it is an object of the present invention to provide a high-frequency heating cooking device with a heater, which can prevent damage to the glass tube heater.

[Configuration of the Invention] (Means for Solving the Problems) In order to achieve the above object, the high-frequency heating cooking device with a heater according to claim 1 has a heater through-hole formed in a housing having a heating and cooking chamber inside. However, in the heater-equipped microwave oven provided through the glass tube heater in the heater through hole, the inside diameter of the heater through hole is set to be larger than the outside diameter of the glass tube heater, and A tubular covering portion having an inner diameter larger than the outer diameter is provided on the periphery of the heater through hole so as to project outward, and the glass tube heater is heated by the holding member held by the tubular covering portion. It is characterized in that it is held so as to secure a gap between the inner edge of the through hole and the inner surface of the cylindrical covering portion.

Further, in the high-frequency heating cooking device with a heater according to claim 2, the portion of the coiled heater wire inside the glass tube heater located outside the heater through hole has a line length within the heating cooking chamber when it is extended. 1 of microwave generated
It is formed to have a wavelength of about 3/4.

(Function) Since the tubular covering portion projects outward, unlike the case where the tubular covering portion projects inside, the electric field concentration of the microwave on the tubular covering portion can be relaxed as much as possible, and the microwave inside the tubular covering portion can be minimized. Combined with the attenuation effect of the, the leakage prevention effect of microwaves can be sufficiently enhanced, and the heating area of the glass tube heater in the heating and cooking chamber does not have to be narrowed by the tubular covering portion, and the heat generation of the glass tube heater can be prevented. The area can be expanded more than before. Moreover, since the gap is secured between the glass tube heater and the inner edge of the heater through hole and the inner surface of the tubular covering portion, the glass tube heater is configured so that the inner edge of the heater through hole is provided at the time of assembly or transportation. It is possible to prevent the glass tube heater from strongly hitting the inner surface of the tube-shaped covering portion and the glass tube heater can be prevented from being damaged.

Further, as in claim 2, a portion of the coil-shaped heater wire inside the glass tube heater located outside the heater through hole has a line length of about 3/4 of one wavelength of the microwave when the portion is extended. It has been confirmed from the experimental results of the present inventor that the microwave attenuating action at that portion is remarkably enhanced if formed so that the effect of preventing microwave leakage can be further enhanced.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

First, in FIG. 5 showing a vertical sectional view of the whole body (outer box is not shown), 11 is a housing having a heating and cooking chamber 12 inside, and a motor 13 is rotatably driven at the bottom thereof. The rotating pan 13a is installed. A lower heater 14 is provided below the rotary plate 13a. The waveguide 15 is attached to the right side wall of the housing 11, and the magnetron 16 is fixed to the waveguide 15. On the other hand, 17 is a reflection plate attached to the upper surface of the housing 11 by welding or the like.
Constitutes a part of the upper surface of the casing 11, and the entire lower surface thereof is open to the inside of the cooking chamber 12 through the rectangular opening 11a. As shown in FIG. 4, the reflection plate 17 is formed in a polygonal arch roof shape, and circular heater through holes 18 are formed in the left and right end plate portions 17a thereof, and the periphery of the heater through hole 18 is covered with a tubular shape. The portion 19 is integrally formed toward the outside by, for example, burring processing. Further, a pair of claw portions 20 is formed at the tip of the tubular covering portion 19. On the other hand, 21 is a glass tube heater in which a coil-shaped nichrome wire 23, which is a coil-shaped heater wire, is inserted into a glass tube 22, and both ends of the glass tube heater are inserted into a heater through hole 18 and a tubular covering portion 19, and this tubular shape Cover 19
Both ends of the glass tube heater 21 are held by an annular insulator 24 which is a holding member fixed to the. In this case, the inner diameters of the heater through hole 18 and the tubular covering portion 19 are the same as those of the glass tube heater.
It is set to be, for example, 2 mm larger than the outer diameter of 21 (12 mm in this embodiment), and a gap of, for example, 1 mm is provided between the outer surface of the glass tube heater 21 and the inner edge of the heater through hole 18 and the inner surface of the tubular covering portion 19 in the above holding state. Is set to be secured. Further, the protruding length of the tubular covering portion 19 is, for example, 3 mm. As shown in FIG. 3, the insulator 24 is fixed by fitting the insulator 24 onto the outer periphery of the tubular covering portion 19 and fitting the claw portion 20 of the tubular covering portion 19 into the groove 25 of the insulator 24. It is bent at a right angle so that it fits in, and then fixed. And glass tube heater
21 Insulators 26 at both ends are formed in a D-shaped cross-section at the tip side portion,
The D-shaped portion 26a is inserted into the D-shaped hole portion 27a of the fixing plate 27 attached to the upper surface of the housing 11 to prevent the glass tube heater 21 from rotating, and the step portion 26b of the D-shaped portion 26a and the fixing plate.
The contact with 27 regulates the lateral movement of the glass tube heater 21.

In this embodiment, the total length L ₁ (see FIG. 5) of the coiled portion of the coiled nichrome wire 23 of the glass tube heater 21 is
The microwave generated by the magnetron 16 is set within the range of 2 wavelengths +7 mm to 2 wavelengths +9 mm. In this case, if the microwave frequency is 2450 MHz, one wavelength is 122 mm, so L ₁ is 251 to 253 mm.

Further, a portion L ₂ (see FIG. 3) of the coil-shaped nichrome wire 23 located outside the heater through hole 18 has a line length 1 of about 3/4 of one wavelength of the microwave when it is extended. Is formed. In this case, if one wavelength of the microwave is 122 mm, the extended line length l of the L ₂ portion is
Is set to 80 to 95 mm. The line length l can be calculated by the following formula.

l = πan + b where a is the winding diameter of the coil-shaped nichrome wire 23, n is the number of turns of the portion L ₂ , and b is the length of the straight tip portion.

In the above configuration, for example, when toasting bread, the bread is housed in the cooking chamber 12 and the glass tube heater 21
Just turn on the power.

According to the present embodiment described above, since the tubular covering portion 19 that partially covers both end portions of the glass tube heater 21 protrudes to the outside, unlike the case where the tubular covering portion 19 protrudes to the inside, a tubular shape is formed. The electric field concentration of microwaves on the coating portion 19 can be relaxed as much as possible, and in combination with the attenuation effect of microwaves due to the inductance of the coil-shaped nichrome wire 23 in the tubular coating portion 19, the effect of preventing microwave leakage can be sufficiently improved. Can be raised. Moreover, it is not necessary to narrow the heat generation area of the glass tube heater 21 in the heating and cooking chamber 12 by the tubular covering portion 19, the heat generation area of the glass tube heater 21 can be expanded as compared with the conventional case, and the heating performance can be improved. Also, power saving can be achieved.

In addition, since the gap is secured between the glass tube heater 21 and the inner edge of the heater through hole 18 and the inner surface of the tubular covering portion 19, the glass tube heater 21 is assembled at the time of assembly or transportation.
Strongly hitting the inner edge of the heater through hole 18 and the inner surface of the cylindrical covering portion 19 can be prevented by the gap as much as possible, and the glass tube heater 21 can be prevented from being damaged.

On the other hand, the line length 1 when the portion L ₂ of the coiled nichrome wire 23 in the glass tube heater 21 located outside the heater through hole 18 is extended is generated in the cooking chamber 12 by the microwave. The reason why it is formed to be approximately 3/4 of one wavelength, that is, 80 to 95 mm is as follows.

That is, when the stretched line length l of the portion L ₂ located outside the heater through hole 18 is close to an integral multiple of 1/2 wavelength of the microwave, the high frequency current at the tip of the coiled nichrome wire 23 becomes maximum. , And conversely, if the line length l is set to 3/4 of one wavelength of microwave, the high frequency current becomes minimum,
Microwave leakage can be significantly reduced. Further, since the portion L ₂ located outside the heater through hole 18 contributes little to heating in the heating and cooking chamber 12, if the line length l is increased, the heating efficiency of the cooked material is reduced and the power consumption is reduced. There is also a circumstance that there are many. The present inventor examined and considered this situation, and the test results are shown in Table 1 below.

As is clear from Table 1, when the wire length l is 70 mm, the surface temperature of the glass tube heater 21 at the time of no-load oscillation becomes too high, which is not preferable, and when the wire length l is 100 mm, the pan 2 It takes too long to toast a piece. Therefore, as in the present embodiment, the line length l is 80 to 95.
mm, that is, approximately 3/4 of one wavelength of microwave is desirable. By setting the dimensions as described above, the toast time can be shortened while the effect of preventing microwave leakage is further enhanced, and power consumption can be reduced accordingly.

Further, in the above embodiment, the entire length L ₁ (see FIG. 5) of the coiled portion of the coiled nichrome wire 23 of the glass tube heater 21 is within the range of 2 wavelengths + 7 mm to 2 wavelengths + 9 mm of the microwave (251 It is set to ~ 253mm), but the reason for setting in this way is as follows.

That is, the left-right width dimension of the reflector 17 is equal to the left-right end plate portions 17
Since the length of two wavelengths (about 244 mm) is set to attenuate the reflected wave of the microwave between a, if the dimension L ₁ is set to a length of two wavelengths or less, both ends of the coiled nichrome wire 23 are The straight portion enters the cooking chamber 12 and acts as an antenna for radio waves, increasing microwave leakage. However, if the dimension L ₁ is made too long, the portions on both sides of the coiled nichrome wire 23 that do not contribute to heating (the portions protruding from the heater through hole 18) increase, and the heating efficiency decreases accordingly. Then, there is a circumstance that power consumption increases. The present inventor examined and considered such a situation, and the test results are shown in Table 2 below.

As is apparent from Table 2, when the dimension L ₁ is 235 to 240 mm, there is a problem that the leaked radio waves increase remarkably, and when the dimension L ₁ is 260 to 265 mm, it is necessary to toast two breads. Time gets too long. Therefore, as in the present embodiment, the dimension L ₁ is 251-253 mm, that is, 2 of the microwave.
It is desirable to set within the range of wavelength + 7mm to 2 wavelength + 9mm. By setting the dimensions as described above, the toast time can be shortened while the effect of preventing microwave leakage is further enhanced, and power consumption can be reduced accordingly.

Although the insulator 24 is used as the holding member for holding the glass tube heater 21 in the above embodiment, any other member may be used as long as it is a heat-resistant dielectric.

In addition, the present invention can be variously modified, for example, the attachment means of the insulator 24 may be changed to an appropriate known means.

EFFECTS OF THE INVENTION As is apparent from the above description, the present invention allows the tubular covering portion to project outward, so that the electric field concentration of microwaves on the tubular covering portion can be alleviated as much as possible and the inside of the tubular covering portion can be reduced. Combined with the microwave attenuation effect, the microwave leakage prevention effect can be sufficiently enhanced, and the heat generation area of the glass tube heater can be prevented by narrowing the heat generation area of the glass tube heater in the heating and cooking chamber due to the tubular coating. The area can be expanded more than before,
The heating efficiency can be improved. Moreover, since the gap is secured between the glass tube heater and the inner edge of the heater through hole and the inner surface of the cylindrical covering portion, the glass tube heater is configured so that the inner edge of the heater through hole is provided at the time of assembly or transportation. It is possible to prevent as much as possible from strongly hitting the inner surface of the tubular covering portion by the above gap,
It is possible to prevent damage to the glass tube heater.

Further, as in claim 2, when a portion of the coil-shaped nichrome wire in the glass tube heater located outside the heater through-hole is extended, the line length is 1
If it is formed so as to be approximately 3/4 of the wavelength, it is possible to remarkably enhance the microwave attenuation effect in that portion,
The microwave leakage prevention effect can be further enhanced.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention.
1 is an enlarged vertical front view of the main part, FIG. 2 is a right side view of the same,
3 is a transverse sectional view of the same, FIG. 4 is an exploded perspective view of the same, and FIG. 5 is a vertical sectional front view of the entire cooking chamber. And, FIG. 6 is a vertical sectional front view of a main part showing a conventional example. In the drawing, 11 is a housing, 12 is a cooking chamber, 16 is a magnetron, 17 is a reflecting plate, 18 is a heater through hole, 19 is a tubular covering portion,
Reference numeral 20 is a claw portion, 21 is a glass tube heater, 23 is a coiled nichrome wire (coiled heater wire), 24 is an insulator (holding member), 26 is an insulator, and 27 is a fixing plate.

Claims (2)

(57) [Claims] 1. A high-frequency heating cooking device with a heater, wherein a heater through hole is formed in a housing having a heating and cooking chamber inside, and a glass tube heater is provided through the heater through hole. Is set to be larger in diameter than the outer diameter of the glass tube heater, and a cylindrical covering portion having an inner diameter larger than the outer diameter of the glass tube heater is projected outward at the peripheral edge of the heater through hole. The glass tube heater is held by a holding member held in the tubular covering portion so as to secure a gap between the inner edge of the heater through hole and the inner surface of the tubular covering portion. High frequency cooking device with heater. 2. A coil-shaped heater wire in a glass tube heater, the portion of which is located outside the heater through hole is extended to have a line length of approximately one wavelength of a microwave generated in a cooking chamber. The high-frequency heating cooking device with a heater according to claim 1, wherein the high-frequency heating cooking device has a three-quarter shape.