JPH02139888A - Electric heating unit - Google Patents

Abstract

PURPOSE:To obtain good electrical characteristics even in a very humid atmosphere by applying the constitution wherein an adiabatic substrate having a groove for leading a coiled heating wire is made mainly of a silica alumina fabric having a bonding agent of clay and alumina sol is housed in a metal casing. CONSTITUTION:An adiabatic substrate 2 comprising an insulation material mainly made of a silica alumina fabric and having a bonding agent of clay and alumina sol is provided with a coil shaped groove 2a. The adiabatic substrate 2 provided with a heating wire 5 is housed in a metal casing 4 and this casing 4 is made integral with a metal top plate 1 with a screw. According to the aforesaid construction, it is possible to obtain good electric characteristics even in a very humid atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electric heating unit used mainly for cooking in ordinary households.

Conventional technology Traditionally, electric heating units for cooking used in general households include electric stoves with spirally wound heating wires placed on ceramics, and units made by winding Sheezheek in a spiral shape. There is an electric range.

In addition to these methods, in Europe and the United States, there is an electric heating system called smooth top, in which a spirally wound heating wire is placed in a groove in the insulation material, a ceramic glass plate is placed on top of the heating wire, and the ceramic glass plate is used as the heating surface. units are widely used.

However, in Japan, electric stoves made of ceramic are still in strong demand because they are inexpensive and have superior thermal efficiency compared to electric heating units such as smooth tops.

Moreover, electric stoves that use traditional ceramics have heating wires that are directly exposed to the outside, which can be dangerous, and the contents of the cooking material can boil over, significantly shortening the lifespan of the heating wires. There were various shortcomings.

Furthermore, since ceramics have a large heat capacity, they are heavy in terms of weight and are difficult to cool down.

After use, it cannot be moved or stored immediately, and it also has a drawback in terms of usability.

For this reason, the present inventors have already provided a top plate made of a metal plate, a spirally wound heating wire, and a groove in which the heating wire is arranged in a meandering manner, and which is mainly made of silica-alumina fibers. It has a heat insulating base made of a heat insulating material as a component, and a storage case made of a metal plate that houses the heat insulating base, and a radiation layer is formed on the side of the object to be heated of the top plate, and an insulating layer is formed on the side of the heating wire. We are proposing a new electric heating unit.

Problems to be Solved by the Invention However, in conventional electric heating units that use a heat insulating material mainly composed of silica-alumina fibers as a heat insulating base,
Because it has excellent heat resistance, heat insulation, and heat insulation properties, there are no major problems in actual use even if it is used at high temperatures, but since it is manufactured using silica sol as a binding material for insulation,
Highly hygroscopic. Therefore, if left in a humid atmosphere, there is a problem in that the electrical characteristics significantly deteriorate.

The present invention solves these problems, and aims to provide an electric heating unit that has excellent electrical characteristics even when left in a humid atmosphere.

Means for Solving the Problems In order to solve the above problems, the electric heating unit of the present invention has the following features:
It has a top plate made of a metal plate, a spirally wound heating wire, and a groove in which the heating wire is arranged in a spiral shape, and is mainly composed of silica-alumina fiber.

It consists of a heat insulating base made of a heat insulating material with clay 2 and alumina sol as binders, and a storage case made of a metal plate that houses this heat insulating base.

Function: As described above, the direct heating unit of the present invention uses alumina sol and clay, which have extremely low hygroscopicity, as binders, and has improved electrical properties in a humid atmosphere.

By the way, in general, products using alumina sol as a binder have poor performance as a binder, and the mechanical strength of the resulting heat insulating material is inferior to that of conventional materials using silica sol as a binder. 1. In the present invention, the above-mentioned problem can be solved by adding clay.

For the above reasons, an electric heating unit using a heat insulating material containing lumina sol and clay as a binder exhibits excellent electrical properties even when left in a multi-component atmosphere.

EXAMPLES Below, one specific example of the present invention will be described based on the drawings.

As shown in Fig. 2, both sides of the top plate 1 made of 5US304 are coated with a heat-resistant paint that is excellent in radiation and heat absorption. The main component is silica-alumina fiber.

A spiral groove 21L is provided in the heat insulating base 2 made of a heat insulating material using clay 2 and alumina sol as binding materials. Note that the heat insulating material is used as the heat insulating base 2 after being heat treated at 80° C. in advance.

Further, in the groove 21LK of the heat insulating base 2, a spirally wound heating wire 3 is disposed. The heat insulating base 2 on which the heating wire 3 is arranged is housed in a storage case 4 made of SUS 304, and the storage case 4 and the top plate 1 are integrated with screws. Further, the top plate 1 and the heat insulating base 2 are integrated with a slight gap. An insulator 6 and an electrical outlet terminal 6 are provided at the bottom 11J11 of the storage case 4.

In order to investigate the moisture resistance characteristics of the electric heating unit of the present invention having such a configuration, it was placed in an atmosphere at 40° C. and 95% relative humidity for one week, and its electrical insulation resistance was measured. The electrical insulation resistance was measured between the top plate 1 or the storage case 4 and the electrical outlet terminal 6.

2. For comparison, measurements were also taken on an electric heating unit using a conventional heat insulating material with silica sol as a binder as the heat insulating base 2. In addition, the number of measurements was six in each case. These results are shown in Table 1.

(Left below) Table 1 As is clear from Table 1, the conventional electric heating units of sample numbers 1 to 5 that use heat insulating materials with silica sol as the main binder have extremely low electric currents of 0.1 to 1 MΩ. Insulation resistance was shown.

On the other hand, the electric heating units of the present invention with sample numbers 6 to 10, which used heat insulating materials whose main binders were alumina sol and clay, exhibited extremely high electrical insulation resistances of 66 to 100 MΩ.

As described above, since the electric heating unit of the present invention has excellent moisture resistance, it exhibits extremely high electrical characteristics even when left in a humid atmosphere.

In Example 2 of the present invention, the heat insulating material was heat-treated at 800° C. in advance.

The heat treatment is not particularly limited to this temperature, but in general, heat treatment at a temperature below the temperature at which the heat insulating material crystallizes provides better moisture resistance.

Effects of the Invention As is clear from the description of the above embodiments, according to the present invention,
It has a top plate made of a metal plate, a spirally wound heating wire, and a groove in which the heating wire is arranged in a spiral shape, and is mainly composed of silica-alumina fiber.

It consists of a heat insulating base made of a heat insulating material using clay p and alumina sol as a binder, and a storage case made of a metal plate that houses this heat insulating base, so it has excellent electrical properties even when left in a humid atmosphere. It is possible to provide an electric heating unit that is

[Brief explanation of the drawing]

The figure is a sectional view of an electric heating unit showing an embodiment of the present invention. 1...Top plate, 2...Insulation base, 2a.
...Groove, 3...Heating wire, 4...Storage case. Name of agent: Patent attorney Shigetaka Awano and 1 other person −
m-? --- 2α-・- -Itten sale + 1'l' Kurebamizo fr! ! 'L storage case

Claims (1)

[Claims] It has a top plate made of a metal plate, a spirally wound heating wire, and a groove in which the heating wire is arranged in a spiral shape, and the main component is silica-alumina fiber, and clay and alumina sol are used as a binder. This electric heating unit consists of a heat insulating base made of a heat insulating material and a storage case made of a metal plate that houses the heat insulating base.