JPH046153Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a ceramic heater for heating a liquid, and more specifically, to a ceramic heater that is disposed in a container containing a liquid and directly heats the liquid.

(Prior Art) In order to improve the heating efficiency of electric pots and other liquid heating devices, ceramic heaters have been proposed that are placed inside a container containing liquid and directly heat the liquid. , an integrated structure is adopted in which a heating resistor is sandwiched between ceramic sheets.

(Problem that the invention aims to solve) However, with conventional ceramic heaters, the heat conduction state during use tends to change due to dirt on the heater surface and the growth of boiling bubbles caused by it, resulting in localized overheating and small There were problems with cracks and damage. Moreover, since ceramic is brittle, it is easily damaged by external impact, and if the ceramic is damaged, there is a risk that liquid may enter the ceramic heater and cause an electrical leak, similar to the case where a minute crack or the like occurs.

In order to solve these problems,
Publication No. 140731 proposes a heater in which a thick buffer layer made of a highly thermally conductive metal material is bonded to the inner wall of the ceiling of an exterior body made of a corrosion-resistant metal material, and a ceramic heater body is pressed into contact with the buffer layer. ing.
With this structure, thermal shock caused by replenishment of cold water can be prevented by the action of the buffer layer interposed between the ceramic heater body and the exterior body, but due to the material of the ceramic heater body, fine pores and irregularities remain on the surface. In addition, simply pressing the ceramic heater body against the buffer layer will result in large thermal resistance at the contact surface between the two, which will not only make it impossible to increase the wattage density, but also prevent local temperature rises due to dry heating. This tends to result in uneven temperature distribution, which may cause cracks.In addition, if the exterior body is damaged and the liquid enters the interior, the liquid that has accumulated inside the exterior body may leak into the ceramic heater body. It has become clear that there is a risk that the electric current may come into contact with the ceramic heater, enter the ceramic heater body through the crack, and cause electrical leakage.

Therefore, the present invention not only prevents thermal shock caused by cold water replenishment, but also improves heat conduction from the ceramic heater body to the outside, thereby preventing local temperature increases caused by dry heating and making the temperature distribution uniform. The main purpose of this is to prevent the occurrence of cracks caused by thermal stress, and also to improve mechanical strength.

(Means for Solving the Problem) In order to solve this problem, the present invention casts a heat sink using a ceramic heater body with a built-in heating resistor as an insert, and embeds the ceramic heater body in the heat sink. The heat dissipating body is enclosed in the cover with its heat dissipating surface closely fixed to the inner wall surface of the corrosion-resistant metal cover.

In the ceramic heater for heating liquids having the above structure, the ceramic heater body is placed in a mold as an insert, molten metal is poured into it, a heat radiator is cast to cover the ceramic heater body, and the heat radiator is placed on its heat radiating surface. It can be manufactured by closely fixing the material to the inner wall surface of a corrosion-resistant metal cover and enclosing it in the cover.

As the material for the heat sink, it is preferable to use aluminum or an alloy thereof, which has excellent corrosion resistance and thermal conductivity.

(Function) By casting the heat dissipation body using the ceramic heater body as an insert, the molten metal enters the pores on the surface of the ceramic heater body without any gaps during casting, and when the molten metal solidifies, it thermally interacts with the ceramic heater body. A heat dissipating body is formed which is strongly bonded both mechanically and mechanically.

This heat dissipation body efficiently releases the heat generated in the ceramic heater body to the outside, makes the temperature distribution uniform, reduces thermal stress, and plays the role of increasing the mechanical strength of the ceramic heater body.
When the heater is rapidly cooled by replenishing cold water, it absorbs the cold heat and prevents thermal shock from being applied to the ceramic heater body, and at the same time absorbs mechanical shock together with the cover to prevent mechanical shock from being applied to the ceramic heater. prevent.

Additionally, in the unlikely event that the cover is damaged and liquid enters the cover, the heat sink will prevent the ceramic heater body from coming into contact with the liquid, and in that case, the ceramic heater body will be damaged or cracked. It serves to prevent liquid from entering the ceramic heater body even if the ceramic heater is

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

FIG. 1 shows a partial cross section of the ceramic heater 1 for heating liquid according to the present invention when it is applied as a heater for an electric pot, and 2 is a ceramic heater main body;
3 is an aluminum heat sink, 4 is a stainless steel cover, 5 is an insulator tube, 6 is a lead wire, and 7 is a protective cover for the lead wire attachment part.The ceramic heater body 2 is placed in a mold with the protective cover 7 covered. ,
It is embedded inside the heat sink 3 by casting molten aluminum therein.

As shown in FIGS. 2 and 3, the heat sink 3 itself is fixed with a plurality of screws 8 with its upper end surface in close contact with the upper inner surface of the cover 4 made of stainless steel. Note that silicone grease or the like may be interposed between the upper end surface of the heat sink 3 and the upper inner surface of the stainless steel cover 4.

The stainless steel cover 4 consists of an upper body 4a and a bottom lid 4b, which are integrated by welding after the ceramic heater body 2 is attached. After installing the seal member 9, the container 1
It is fixed by inserting it into the bottom through-hole of 0 and tightening it with a nut (not shown).

With the above configuration, it is possible to prevent the ceramic heater body 2 from being damaged or cracked due to thermal stress or external impact, and even if a minute crack or damage occurs, it is buried in the heat radiator. , electric leakage can be prevented, and the original shape is maintained without shattering, so if the ceramic heater main body 2 has multiple heating resistors, by connecting a resistor in parallel, one heating resistor can be disconnected by cracking. Even if the wire is broken, it can be used as is.

(Effects of the invention) As is clear from the above explanation, according to the invention, the heat sink is cast with the ceramic heater body as an insert, and the ceramic heater body is embedded in the metal lump forming the heat sink. , the heat radiator and the ceramic heater body can be firmly bonded both thermally and mechanically. Therefore, even if the ceramic heater body generates abnormal heat due to dry firing, the heat will not flow through the heat radiator. Since the heat is efficiently discharged to the outside through the ceramic heater body, the temperature distribution in the ceramic heater body can be made uniform and thermal stress can be reduced, and the watt density of the ceramic heater body itself can be increased and the heater can be made smaller.

In addition, the ceramic heater body is embedded in the heat radiator to increase its mechanical strength, and the heat radiator is surrounded by a cover.
Since thermal shock and mechanical shock due to cold heat when replenishing cold water are prevented from being applied to the ceramic heater body, cracks can be prevented and the life of the heater can be extended.

Furthermore, since ceramic heaters are double-protected by a heat sink and a corrosion-resistant metal cover, even if the cover is damaged and liquid enters the cover, there will be no damage or cracks to the ceramic heater body. Even if this occurs, the heat radiator prevents the liquid from coming into contact with or entering the ceramic heater body, thereby providing excellent effects such as being able to prevent electrical leakage.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main part of the ceramic heater for heating liquid according to the present invention when it is used as a heater for an electric pot, Fig. 2 is a partial bottom view thereof, and Fig. 3 is taken along line A-A in Fig. 2. FIG. 1... Ceramic heater for liquid heating, 2... Ceramic heater main body, 3... Aluminum heat sink, 4... Stainless steel cover, 5... Insulator tube, 6... Lead wire, 7... Lead wire attachment Protective cover, 8...screws.

Claims (1)

[Scope of utility model registration request] a ceramic heater body having a built-in heat generating resistor; a heat radiator made of a metal block that is cast with the ceramic heater body as an insert and in which the ceramic heater body is embedded; a heat radiating surface of the heat radiator is closely fixed to an inner wall surface; A ceramic heater for heating a liquid, comprising a corrosion-resistant metal cover that encloses the heat radiator.