JPH0429941B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cooking device, such as an electric oven or a microwave oven with a heater, that heats an object in a heating chamber using the heat of a heater.

BACKGROUND ART FIG. 4 is a sectional view showing a conventional heating cooker. In FIG. 4, a heating chamber 1 is provided with an upper heater 2 at the upper part and a lower heater 3 at the lower part, and is configured to heat food placed on a saucer 4 and cook it. Furthermore, a magnetron 6 is provided and radio waves are irradiated into the heating chamber via a waveguide 7 to heat the food 5 by radio waves. This is a so-called combined heating oven using a heater and radio waves.

FIG. 5 is a perspective view of a heater 3 used in a conventional heating cooker.

Problems to be Solved by the Invention However, since the upper heater 2 and lower heater 3 of such a conventional heating cooker are exposed in the heating chamber 1, the effective volume of the heating chamber is reduced by this amount. In order to be able to store large foods, the heating chamber 1 needs to be enlarged by the size occupied by the heater, and the external size also becomes large, requiring a large installation space, making it difficult to use as a heating cooker. I was getting used to it. Furthermore, if the heater is exposed in the heating chamber, even if food stains are scattered on the walls of the heating chamber, the heater gets in the way and is difficult to clean, making it inconvenient to use.

Furthermore, since the heaters 1, 2, and 3 are exposed in the heating chamber, the object to be heated 5 may directly receive the radiant heat from the upper heater 1, causing local heating unevenness that conforms to the shape of the heater 1. There were also problems.

In order to solve this problem, a configuration was proposed in which the heater was placed outside the heating chamber and installed in a planar configuration, but with this configuration, the heat from the planar heater could not be efficiently transferred into the heating chamber. Since there is no heating chamber, thermal efficiency is poor, and contact with the sheet heater tends to occur locally due to thermal deformation of the heating chamber wall surface. This local contact causes uneven heating of the heated object and
There were also problems such as wire breakage and insulation deterioration due to local heating of the sheet heater itself.

The present invention solves these conventional problems, and provides a highly reliable heating cooker that has excellent thermal efficiency, is easy to use by clearing the heating chamber, has good heating performance, and is less likely to malfunction. It provides:

Means for Solving the Problems In the heating cooker of the present invention, the heater is formed into a planar shape and is arranged so as to cover almost the entire area outside the heating chamber ceiling surface. external,
That is, a gentle convex surface is formed on the side of the planar heater. Further, the sheet heater is fixed to the ceiling surface of the heating chamber through a heat-resistant insulator with a metal holding plate, and the metal holding plate has a thin groove extending from the center toward the outer periphery. The holding plate is provided on the heating chamber ceiling surface so as to be slidable in the plane direction of the holding plate, thereby achieving uniform and reliable surface contact between the heating chamber ceiling surface and the sheet heater. be.

Effects According to the present invention, the planar heater is provided outside the top surface of the heating chamber, and since the ceiling surface of the heating chamber is pre-convex toward the planar heater side, as heating progresses, thermal expansion causes the heating chamber to expand. The ceiling surface further curves into an arch toward the side of the planar heater.
At this time, the holding plate of the sheet heater is fixed so as to be slidable in its plane direction, so the sheet heater is bent while being curved to match the degree of convex curvature of the ceiling surface of the heating chamber. Trying to press against the heating chamber ceiling. This is where the cut grooves in the holding plate come into play. In other words, if the holding plate is just a flat plate, as the heating chamber ceiling curves, the holding plate will also curve into a mountain shape, but the material on the outer periphery will be left flat and deformed into a wavy shape. I have no choice but to do it. This wavy deformation makes it difficult to bring the planar heater into close contact with the entire ceiling surface of the heating chamber, making it impossible to achieve its original purpose. Since the present invention has grooves radially extending from the center of the holding plate toward its outer periphery, it is possible to absorb the extension of the outer periphery and accommodate any degree of curvature of the ceiling surface of the heating chamber. It becomes possible to reliably bring the entire surface of the sheet heater into close contact, and the heat of the sheet heater is uniformly and efficiently transmitted to the top surface of the heating chamber and further to the object to be heated in the heating chamber. In addition, the higher the temperature of this planar heater, the more uniformly it comes into contact with the top surface of the heating chamber, which makes the heat dissipation of the heater more uniform and prevents malfunctions such as insulation deterioration due to localized heating and disconnection of heater wires. will also disappear. Due to these effects, even if the heating element is provided outside the heating chamber, the food can be effectively heated, and of course, the heat distribution is made uniform, so that even baking can be achieved. Furthermore, since there is no need for an exposed heater inside the heating chamber, the effective volume within the heating chamber is increased, and the usability can be improved, such as easy cleaning.

When fixing the holding plate of a sheet heater, it is done with screws with a slight gap, and there is no waving phenomenon on the outer periphery of the holding plate, so it can be fixed sufficiently with a small number of screws, reducing assembly man-hours and improving work efficiency. Very good.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a front sectional view showing the structure of the cooking device according to the present invention. In FIG. 1, a sheet heater 8 is provided in close contact with the outer surface of the ceiling or bottom of the heating chamber 1. The planar heater 8 is fixed by a metal plate 9 for attaching the heater. 10 is a heat insulator for preventing heat from escaping to the outside. Further, the magnetron 6 is provided in the waveguide 7 and is used to heat the object 5 placed on the object mounting plate 4 with high frequency. With the above configuration, the object to be heated 5 can be heated by both heater heating and high frequency heating.

FIG. 2 is a partial sectional view showing the structure of the upper planar heater 8 in detail, and FIG. 3 is a perspective view showing the structure of each component of the planar heater 8 and the heater pressing plate 9. In Figures 2 and 3,
The planar heater 8 has a structure in which a heating element 8a is wound around a winding frame 8b made of a heat-resistant insulator such as mica, and the upper and lower sides of the winding frame 8b are sandwiched between insulating plates 8c also made of mica or the like. The heater holding plate 9a has several elongated holes radially extending from its center, and stepped screws 11 are inserted into the elongated holes, and the sheet heater 8 is tightened on the top surface of the heating chamber 1 while holding it in a sandwiched manner. There is. Further, this heater pressing plate has a diagonal portion cut away from the center toward the outer peripheral corner.

With the above configuration, even if heating progresses and the surface heater 8 or the heater presser plate 9 undergoes thermal expansion, the pressure in the vertical direction of the stepped screw 11 is not so strong, and it is tightened in the elongated hole. Therefore, the holding plate 9 expands in the plane direction. However, since the ceiling surface of the heating chamber has a box-shaped periphery, the force of thermal expansion acts in the vertical direction and tends to curve upward. Therefore, the heater holding plate 9
is pushed up tightly against the curvature of the heating chamber ceiling surface, and can be brought into close contact with the entire heating chamber ceiling surface naturally while narrowing the gap in the notch portion of the outer peripheral corner.

Effects of the invention According to the above invention, the following effects can be achieved.

(1) The holding plate of the sheet heater can be slid and the waving phenomenon when bending is eliminated, so the heating chamber surface and the sheet heater are in good contact at any stage during heating, and heat conduction is improved. is carried out efficiently and efficiency is improved.

(2) Local heating by the heater is eliminated, uneven heating is reduced, and cooking performance is improved.

(3) Similarly, localized heating of the heater is eliminated, which reduces failures such as disconnection of the heating element and insulation deterioration.

(4) Even if the heater is moved outside the heating chamber, a highly efficient heating chamber can be created, so there are no unnecessary protrusions inside the heating chamber, and the cooking device becomes clear and easy to clean.

(5) Since the heating chamber wall always deforms only in one direction during heating, it is possible to design stable heat distribution performance even during high frequency heating, and it is possible to reduce uneven high frequency heating.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a heating cooker according to the present invention, FIG. 2 is an enlarged cross-sectional view of a heater attachment part of the same heating cooker, FIG. 3 is an exploded perspective view showing the configuration of the heater attachment part and the heater, and FIG. FIG. 4 is a sectional view of a conventional heating cooker, and FIG. 5 is a perspective view of a heater of the same cooker. 1... Heating chamber, 2... Upper heater, 3... Lower heater, 4... Heated object mounting plate, 5... Heated object, 6... Magnetron, 7... Waveguide, 8...
Planar heater, 8a... heating element, 8b... winding frame, 8
c... Insulating plate, 9a... Heater holding plate (top),
9b... Heater holding plate (bottom), 10a... Heat insulating agent (top), 10b... Heat insulating material (bottom), 11... Stepped screw, 12... Heater mounting band.

Claims (1)

[Claims] 1 A heating chamber for heating an object to be heated, and an electric heating device for electrically heating the object to be heated, the electric heating device being a planar heater disposed over almost the entire outer surface of the ceiling surface of the heating chamber, The heating chamber ceiling surface is
The planar heater is configured to form a gently convex surface on the side of the planar heater, and the planar heater includes:
A metal holding plate is brought into pressure contact with the ceiling surface of the heating chamber via a heat-resistant insulator, and the holding plate is configured to have at least one groove cut radially from the center toward the outer periphery. At the same time, in the plane direction of this holding plate, it is slidable,
A heating cooker, characterized in that it is installed on the ceiling surface of the heating chamber.