JP2722677B2 - Electric heating device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electric heating device such as an electric oven and a microwave oven.

2. Description of the Related Art In an electric heating apparatus that arranges electric heating elements on upper and lower wall surfaces of a heating chamber and heats an object to be heated housed in the heating chamber, the outer surface of the heating element is usually subjected to heat insulation processing. Is different depending on the configuration of the electric heating element, but a relatively soft and flexible heat insulating material such as glass wool or asbestos is provided on the outside of the heating element, and furthermore, a metal made of metal is used for fixing the heat insulating material. Generally, a holding plate is provided outside the holding plate.

When the heat insulating material is a planar heating element,
It is provided so as to be in close contact with the heat source and to cover the entire surface so that there is no exposed portion, while in the case of a coil heating element sealed or inserted in a glass tube, it is necessary to provide the outside of the glass tube with this. In general, a metal reflection plate is provided with a large gap therebetween, and the heat insulating material is further provided outside the metal reflection plate.

The above-mentioned heat insulating material usually has an air layer between fibers or materials constituting the heat insulating material, and this air layer plays a role of heat insulation. In general, air itself has an extremely effective heat insulating property, but convection tends to occur, resulting in a large heat loss. Therefore, in order to avoid convection, confine the air in a small space, or provide fine fiber-like obstacles everywhere to prevent convection, and make use of only the heat insulation of the air. Insulation material.

On the other hand, the wiring connection part and the lead wire of these electric heating elements are electrically insulated, and the heat insulating material outside the heating element or the metal holding plate that holds it becomes high temperature as well as the heating element. The wires and wiring connection parts must have heat resistance enough to withstand contact with them, or have rigidity so that they are not connected.

Normally, a part of the wiring passes above the upper heating element and passes below the lower heating element, and these are led to the control room in which the heater control device is housed.

The wiring over such a heating element often uses a high heat-resistant material for covering the copper wire. In addition, these are supported by a plurality of resin holders or the like so as not to contact the edge of the metal holding plate.

Or, as shown in Japanese Utility Model Publication No. Sho 62-30300,
A metal relay plate may be used.

Problems to be Solved by the Invention In the above configuration, electric heating elements are provided above and below the heating chamber, and a heat insulating material, a metal fitting for fixing the heat insulating material, and the like are provided outside the heating chamber in a laminated manner. Further, there is an outer shell material that covers these, and the outer shell material is usually made of metal, and it is necessary to ensure electrical insulation between both the heating chamber and the outer shell metal.

It is sufficient if there is enough space here, but then the effective size of the heating chamber is relatively small compared to the size of the entire device, which is disadvantageous in terms of installation area and product price, which is uneconomical There were drawbacks.

Although it has a fine and large air layer,
The fibrous material such as glass wool and asbestos itself has a role of heat transfer. Therefore, if the distance between the outer shell and the wall of the heating chamber is small, and the heat insulating structure of the heating element is in contact with the outer shell, heat is directly transmitted to the outer shell by conduction, and the surface temperature of the outer shell becomes rather high. Sometimes. Further, when the heat insulating structure almost occupies the space with the shell material, there is a problem that it is difficult to secure an insulation distance for electric wiring of the heating element. Insulation materials made of glass wool, in particular, are electrically insulating, but have high hygroscopicity, and when moisture is generated by heating the object to be heated, moisture adheres to this part, resulting in extreme electrical insulation. In this case, there is a problem that it is highly dangerous to arrange the electric power near the heat insulating material.

Further, according to the example of Japanese Utility Model Publication No. Sho 62-30300, there is a problem in securing the strength of the metal plate to be relayed and securing the insulation distance.

Therefore, a first object of the present invention is to provide a heat insulating structure that does not increase the temperature of the surface of the outer member even when the space between the surface of the heating chamber and the outer member is narrow and an air insulating layer cannot be secured.

A second object of the present invention is to provide an electric wiring for a heating element in such a very narrow space.
An object of the present invention is to provide a connection method capable of securing an electrical insulation distance and securing heat resistance.

Means for Solving the Problems To achieve the first object, the present invention provides a box-shaped heating chamber for storing and heating an object to be heated, a plurality of electric heating elements provided on upper and lower surfaces of the heating chamber, In the electrothermal heating device comprising an outer shell material that covers and covers, a metal reflector is provided outside a part of the electric heater with a necessary gap therebetween, and the reflector has at least a surface on the heater side. Along with performing a high reflectance surface treatment, a plurality of porous heat insulating materials having a metal reflective thin film in close contact with the reflecting plate are provided on the outside thereof, and the outermost layer of the heat insulating material is provided on the inner surface of the outer shell material. In order to achieve the second object, in order to achieve the second object, a box-shaped heating chamber for storing and heating an object to be heated, a plurality of electric heating elements provided on upper and lower surfaces of the heating chamber, An electric heating element disposed adjacent to the chamber; A control room for accommodating a control device for controlling the heating device, and an outer heating member for housing and covering the whole of the control room, provided at a position farthest from the control room and on a metal heat insulating plate outside the heating element. The electrical connection terminal of the heating element and the connection terminal near the entrance of the control room are located almost in the middle between the outer shell and the metal heat insulating plate, and the outer shell and the wall material of the heating chamber are deformed. The relay connection is made by a metal plate having a holding member made of an insulating material at the portions closest to each other.

According to the first configuration, when the heating element is a planar heating element, thermal energy emitted from the heating element is first conducted because the heating element is in close contact with the wall of the heating chamber (usually made of a metal plate). To the heating chamber to uniformly heat the heating chamber. Such heating means for uniformly heating the entire heating chamber is applied to so-called oven cooking. Normally, in the case of a planar heating element, a heat insulating material is provided outside the heating element, and a reflecting plate is further provided thereon. At this time, the reflection plate plays a role as a heat insulation plate for appropriately holding the heat insulating material, rather than a role of reflecting the heat battle. Therefore, the heat energy directed in the opposite direction to the wall surface of the heating chamber, that is, outward, is temporarily blocked by the heat insulating material, reflected by the reflector (heat insulating plate), and returned to the heating element again. Nevertheless, the temperature rises outside the reflector and heat is radiated further outward from here.

On the other hand, in the case of a glass tube heater, there is a space between the tube heater and the reflection plate, and if the shape of the reflection plate is appropriately designed and processed, the heat ray directed to the reflection plate is irradiated toward the object to be heated. . However, since the reflector itself is heated,
This outer surface heats up and dissipates heat further toward the outside, ie the shell.

In any case, by providing a porous heat insulating material having a metal reflective thin film in close contact with the reflector, heat rays are reflected, shielded, and diffused by the metal reflective thin film, and then heat shielded by the heat insulating material. You. In addition, since this is provided over a plurality of layers, the temperature drop is remarkable.
The outermost layer of the heat insulating material does not have an air heat insulating layer that easily causes natural convection or the like when it comes into contact with the inner surface of the outer shell material. The air heat-insulating layer has an effective heat-insulating property, but has a problem that the temperature of the portion rises when convection is involved. Therefore, it is effective to insulate only the air layer that does not generate convection in the heat insulating material.

Further, according to the second configuration, a wiring configuration that can secure electrical insulation in an extremely narrow space, has no concern about heat resistance, and can sufficiently cope with a change in insulation distance due to deformation of an outer shell material or a wall of a heating chamber. You can choose.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to FIG.

1 and 2, sheet heating elements 4 and 5 are provided on the ceiling surface 2 and the bottom surface 3 of the heating chamber 1 on the outside of the metal plate constituting the heating chamber 1 in close contact with each other. The surface 2 is provided with a heating element 6 (hereinafter, referred to as a glass tube heater) composed of a coil heater inserted into a glass tube, in addition to the sheet heating element 4.

The sheet heating elements 4 and 5 are formed by winding a strip-shaped heating element made of an iron-chromium-based material around a thin plate made of an inorganic material such as mica, and furthermore, on both outer surfaces of the sheet heating element, a sandwich made of the same inorganic material thin plate.

At the time of installation, the wall material of the heating chamber is usually a metal plate and has high heat conductivity, so that the conduction heat is efficient as a method of transmitting heat. That is, the planar heating element is used when heated by conduction heat. In the glass tube heater 6, a linear heating element 7 made of an iron-chromium-based material is formed in a coil shape, inserted into a quartz tube or a crystallized glass tube 8, and connected to both ends via insulators or the like. It has a configuration with terminals.

Since the glass tube heater 6 is used to irradiate the cooked food in the heating chamber with the radiant heat of the red-heated coil, if this is provided outside the heating chamber, many small openings are formed in the wall of the heating chamber. The radiant heat is radiated into the heating chamber through this. Generally, ceiling 4 of heating room
In many cases, the connection terminal is pulled out to the outside, and the heating section itself is often provided inside the heating chamber.

As described above, the planar heating elements 4 and 5 heat the wall surfaces of the heating chamber itself by conduction heat, and the glass tube heater 6 directly heats an object to be heated by radiant heat. The difference between these heating methods is convenient because it can cope with various types of cooking.

Further, heat insulating materials 9 and 10 mainly composed of glass fibers are provided outside the sheet heating elements 4 and 5, and heat insulating plates 11 and 12 are integrally formed with the heat insulating materials 9 and 10 and the sheet heating elements 4 and 5. keeping. The heat insulating plates 11 and 12 are made of metal, and the inner surfaces thereof are subjected to a process with high reflectance.

The glass tube data 6 is inside the heating chamber, and its ceiling also serves as the reflector 13 of the heater. The reflecting plate 13 is formed so that its cross-sectional shape approximates to a parabola whose focal point is near the object to be heated. The inside of the parabolic curved surface is subjected to a process having a high reflectance, for example, a pride process.

As described above, the sheet heating elements 4 and 5 are attached to a relatively flat portion of the wall of the heating chamber, whereas the glass tube heater 6 partially covers the wall of the heating chamber (in this case, the ceiling 4) as a parabola. Since it is attached so as to penetrate the inside of the processed part, the wall of the heating chamber has a locally raised part.

Therefore, the distance between the locally raised portion and the outer shell 14 is extremely close. Therefore, the insulation of this part does not lower the temperature of the outer shell member 14 only by providing a normal heat insulating material. If the thickness of the heat insulating material is increased, the outer shell 14 will be pushed up from the inside, causing a problem in appearance.In addition, the heat insulating material is compressed, the air layer in this part is reduced, and the conductive heat using the glass fiber itself as a medium Outer shell 14
May rise in reverse.

Here, a glass fiber heat insulating material 16 to which an aluminum foil 15 or the like is adhered is provided. First, the surface of the aluminum foil 15 is brought into close contact with the outer surface of the reflection plate 13, thereby performing thermal decomposition by blocking and transmitting radiation heat rays on the surface. Fiberglass insulation 16
Acts as a poor conductor of heat. Further, a glass fiber heat insulating material 16 to which an aluminum foil 15 is similarly adhered is further laminated thereon. In this case, a material in which aluminum foil 15 is attached to both surfaces of glass fiber heat insulating material 16 may be used. By overlapping these layers, the heat reaching the outer shell 14 can be reduced. The outermost insulation 16 is aluminum foil 15
Instead, the glass fiber insulation itself directly touches the shell material 14. When the metal foil 15 is in contact with the shell 14, heat dispersion and heat conduction are remarkable here, which may increase the shell surface temperature.

With the above-described configuration, the thickness of the heat insulating material itself can be relatively reduced, and the problem that the outer shell 14 inflates can be eliminated.

Also, as shown in FIGS.
Is located behind the ceiling and penetrates left and right, and has wiring terminals 17 and 18 on both sides. In addition, upper surface heat distribution body 4
Is located in front of the ceiling of the heating chamber and also has connection terminals 19 and 20 on the left and right.

In order to guide the electrical connection of these heating elements to the control room 21 on the right side, the left connection is to attach an insulator 22 on the heat insulating plate 11 of the sheet heating element 4 and to attach it to the surface heating element 4. One of the connection terminals 17 and 19 of the glass tube heater 6 is connected, an insulator 23 is also provided in the right control room, and a U-shaped or L-shaped cross section is formed so as to bridge both insulators 22 and 23. Attach the relay metal plate 24. The electrical connection of the terminals is obtained by directly screwing the relay metal plate 24 with a metal screw.

Although the relay metal plate 24 is on the heat insulating plate 11 of the sheet heating element, the surrounding environmental temperature is high when the heater is energized,
The material must be a material having sufficient heat resistance, have a structure that itself has little heat storage, and have a good heat dissipation position.

In the present embodiment, a stainless steel plate is used and formed so as to have a downward U-shaped cross section, and is located between the outer package 14 and the heat insulating plate 11 so as to be in contact with the surrounding air layer. Also, since it is a metal plate, in order to secure an insulation distance even when bending or thermal deformation occurs at the intermediate portion or when the outer member 14 is dented due to external force, as shown in FIG. A heat-resistant insulating support member 25 is provided in the middle of the plate 24 so as to penetrate it vertically.

The insulating support member 25 is in contact with the heat insulating plate 11 and the outer shell 14.

The insulator 22 provided on the heat insulating plate 11 has protrusions as shown in FIG.
22a is partially formed, the top of which protrudes above the connection metal plate 24, the connection terminals such as the heaters, and the heads of the metal screws for fixing these, so that even if the outer shell 14 is recessed and comes close to this. However, the insulation distance between the screw and the connection terminal can be ensured prior to the protrusion 22a.

Further, even when the heat insulating plate 11 and the upper surface 2 of the heating chamber are deformed upward due to thermal expansion, the insulating distance between the heat insulating plate 11 and the relay metal plate 24 is kept constant because the insulator 22 itself is lifted together.

Effects of the Invention As described above, according to the present invention described in claim (1), the following effects can be obtained.

(1) Since the inner surface of the reflector is subjected to a surface treatment having a high reflectivity and a metal foil having a high thermal conductivity is provided in contact with the outer surface, radiant heat is shielded and diffused, and the outer surface of the outer material is protected. The temperature can be lowered.

(2) By providing a plurality of layers of the heat insulating material and arranging the heat insulating material so as to be in contact with the inner surface of the outer shell, an air layer that does not generate convection can be obtained, and the surface temperature of the outer shell can be reduced.

(3) By arranging the heat insulating material in contact with the inner surface of the outer material, the thickness of the air heat insulating layer does not change due to the deformation of the outer material, so that a constant surface temperature can always be ensured, and It does not deform even when an abnormal external force is applied.

According to the present invention, the following effects can be obtained.

(1) By bridging the relay metal plate to a narrow space between the shell and the heat insulating plate and electrically connecting the relay metal plate, the insulation distance is kept constant, and the danger such as short circuit can be avoided.

(2) By providing the insulating support member in the middle of the relay metal plate, the insulation distance can be ensured even when the outer shell is deformed.

(3) By arranging the connecting portion between the relay metal plate and the heating element on the heat insulating plate, the insulation distance between the relay metal plate and the heat insulating plate is kept constant by thermal deformation of the heat insulating plate.

[Brief description of the drawings]

FIG. 1 is a sectional view of an electric heating apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a glass tube heater portion of FIG.
FIG. 4 is a top view of the electric heating apparatus according to the embodiment of the present invention, FIG. 4 is a partial sectional view around the insulator 22a in FIG. 3, and FIG. 5 is a partial sectional perspective view around the support member 25 in FIG. . 4,5 ... planar heating element, 6 ... glass tube heater, 9,10 ...
Insulation material, 11,12 ... Insulation plate, 13 ... Reflection plate, 14 ... Outer shell material, 15 ... Metal reflection thin film, 16 ... Insulation material, 21 ... Control room, 22,23 ... Insulator , 24… relay metal plate, 25… support member.

Claims (2)

(57) [Claims] 1. A box-shaped heating chamber for accommodating and heating an object to be heated, a plurality of electric heating elements provided on the heating chamber and upper and lower surfaces, and a shell material for accommodating and covering these heating elements. A metal reflection plate is provided on a part of the outside with a necessary gap therebetween, and this reflection plate is subjected to a surface treatment with a high reflectance at least on the surface on the side of the heating element, and is further in close contact with the reflection plate on the outside. Provided over a plurality of layers a porous heat insulating material having at least one surface of a metal reflective thin film having high thermal conductivity,
An electric heating apparatus, wherein the outermost layer on the non-metal side of the heat insulating material is in contact with the inner surface of the outer shell material. 2. A box-shaped heating chamber for storing and heating an object to be heated, a plurality of electric heating elements provided on upper and lower surfaces of the heating chamber, and a plurality of electric heating elements disposed adjacent to the heating chamber. A control room for accommodating the control device to be controlled, and an outer shell material for housing and covering the entirety, and at a position farthest from the control room,
And, between the electrical connection terminal of the heating element provided on the metal heat insulating plate outside the heating element and the connection terminal near the entrance of the control chamber, is located almost in the middle between the shell material and the metal heat insulating plate. An electrothermal heating device configured to be connected to a metal plate having a holding member made of an insulating material at a portion closest to each other by deformation of an outer shell material and a wall material of a heating chamber.