KR200399652Y1 - Hot plate having thick membrane type heating element - Google Patents

Abstract

The present invention is a heating element is formed on a glass substrate or stainless steel, and a material for the nano film ceramic and metal material is contained in the thick film-type heating element and the thick film-type heating element that generates heat by converting electrical energy into thermal energy is provided. The present invention relates to a hot plate provided with a thick film-type heating element, and in particular, the thick film material used in the present invention contains a material having a property of not being easily oxidized at a high temperature, and thus, unlike a conventional metal heater, The durability of the heating element according to the use and the change of temperature is small and the resistance change is small, so the temperature characteristic of the thick film type heating element can be used more stably than the general metal. Therefore, it consumes less material, is thinner and lighter, and can generate instantaneous heat compared to conventional heaters, and the time taken to raise and lower the temperature to be used is significantly shortened, which greatly reduces the waste of power. Also, crystallization using ceramic materials The thick film type heating element can be formed on the glass material by printing process, so that the structure and shape of the heater can be freely formed, and it is effective to greatly expand the performance and application range of the heater, and the maximum operating temperature is higher than 800 ℃. It can be used for food cooking hot plates, semiconductor silicon wafer preheaters, and aerospace devices.

Description

Hot plate having thick membrane type heating element

The present invention relates to a hot plate, and more particularly, to a cooking hot plate provided with a thick film type heating element consisting of a cermet, a noble metal and a glass powder on a substrate.

In general, the heater uses a metal material such as nichrome wire, tungsten, molybdenum, or the like as a heating material, and mainly has a coil form or a plate form. Appliances using such heaters in daily life include electric stove, coffee pot, electric iron, electric heater, rice cooker, electric frying pan, electric blanket, electric stove, toaster, electric dryer, hot plate, etc. It is also used in various forms in the field.

However, when the heating material is in the form of a coil, it causes a lot of difficulties in implementing the structure of the heater product, and a lot of time is required to raise and lower the temperature, resulting in a problem that power waste is increased due to poor energy conversion efficiency. In addition, the three-dimensional structure of the coil form is due to the structure, the volume of the product becomes large, the weight is heavy, and another problem that the consumption of the heat generating material increases.

In the case where the heating material is in the form of a plate, the substrate directly contacting the cooking utensil and the plate-type heating material are spaced apart, or the heating material is separately provided inside the substrate, thereby increasing the use of the heating material, thereby increasing electrical efficiency. This is a situation where problems such as deterioration have occurred.

Accordingly, the present invention is designed to solve the problems of the conventional metal heating elements such as nichrome, tungsten, molybdenum are bulky and heavy, oxidized or disconnected when used for a long time and takes a long time when heated at high temperature, has a thick film structure The structure and shape of the heating device can be freely deformed, so that the structure of the product can be easily realized and light, and the thick film that can greatly expand the performance and its application range such as suppressing the waste of power due to its excellent energy conversion efficiency. It is an object of the present invention to provide a hot plate with a heating element.

In order to achieve the above object, the cooking hot plate of the present invention in a hot plate,

A substrate made of heat resistant tempered glass or stainless steel;

A thick film-type heating element which forms a thick film by sintering and attaching a conductive cermet and a paste including a precious metal and a glass powder selected from the group consisting of platinum, gold, silver and alloys thereof to one side of the substrate; And

It is connected to the heating element, it characterized in that it comprises an electrode for generating a heating element by supplying an external current.

Hereinafter, the present invention will be described in detail.

At this time, if there is no other definition in the technical terms and scientific terms used, it has a meaning commonly understood by those of ordinary skill in the art.

In addition, repeated description of the same technical configuration and operation as in the prior art will be omitted.

The hot plate for cooking according to the present invention is a heating device, which uses a conventional thick film printing method on a stainless steel substrate coated with heat-resistant tempered glass or crystallized glass powder, and generates a heating element from a paste containing a conductive cermet, a noble metal material, and a glass powder. And a thick film-type heat generating part connected to a power supply for supplying electric energy to the heat generating element to be converted into heat energy.

In addition, the structural feature of the hot plate is a problem caused by the separation of the conventional substrate and the heating element, by directly printing and bonding the heating element in the form of a thick film on the substrate, in the case of the conventional hot plate, the heating portion is located inside the substrate It is composed separately, so that the amount of heating material used is high, and the use of expensive heating material is greatly reduced, thereby reducing the manufacturing cost and lightening the product, and it is possible to form various types of thick film heating parts in terms of design. The time required to raise and lower the speed can be significantly shortened, which greatly reduces the waste of power.

In general, the thick film printing technique is a printing technique widely used in the electronic component process and the advertisement production process, ink mixed with organic materials (PVB: poly vinyl buthral, silicone antifoaming agent, dispersant, solvent, etc.) in addition to the heating material based on cermet. A thick film having a thickness of about 5 μm to 2 mm is printed on a substrate or a substrate by using a material configured to be used as a sintered material. In this relatively simple process, a thick film heating element and an electrode may be sintered to the substrate. However, in order to form the thick film type heating element and the electrode, the material selection has similar thermal expansion coefficients, and the heating material constituting the substrate and the thick film type heating element must be sintered and melt-bonded at 1,000 ° C., so the firing condition is an important parameter. Works. This is because a large difference in coefficient of thermal expansion between the substrate and the heating material may cause the heating element to fall or cause disconnection, and the substrate may break.

Therefore, in the present invention, the substrate is an electrical insulator and selects a material having a small change and deformation having a thermal expansion coefficient of 10 × 10 ⁻⁶ mm / ° C. or less due to the material characteristics of the substrate, and uses a thick film type heating element. It is preferable to select and use a heating material having a thermal expansion coefficient of about 5 to 10 X10 ^-6 mm / ℃ within the temperature range. Specifically, the substrate is made of a heat-resistant glass substrate or crystallized glass powder having excellent insulation, heat resistance and strength. A stainless steel substrate (hereinafter referred to as a substrate) coated with an insulating film is used. The heating material is cermet (ceramic-metal compound), precious metal and glass powder composed of platinum (Pt), gold (Au), silver (Ag), and alloys thereof. It is advisable to uniformly print the heating circuit designed to achieve the calculated electrical resistance value in the designed area using the included material and to sinter the high temperature bond. The. At this time, in the present invention, it is preferable to use the predetermined amount by selecting the organic material (PVB: polyvinyl buthral, silicone antifoaming agent, dispersant, solvent) as necessary to paste the heating element.

In this case, when the substrate material is an iron plate, it is preferable to first print a crystallized glass powder having a similar expansion coefficient with an insulating material, and then print and sinter the thick film type heating element thereon.

In addition, the thick film-type heating element should be a heating material that is configured to have a high current density (3A / ㎜ or more) per printed width, and the thick film of the thick film to withstand the power (watts) breaking strength so as not to be a problem in high power It is desirable to form the thickness to be 10 microns or more, and to meet the precise printing and sintering conditions such that the error and uniformity of the printed heating part thickness and width are 5% or less. Specifically, a heat-generating material that does not oxidize even for a long time of use and has a small change in specific resistance even at high temperatures. In the present invention, a paste containing 20 to 35 parts by weight of precious metal and 45 to 55 parts by weight of glass powder is mixed in 100 parts by weight of the conductive cermet. It is used as a heating material to be printed on and sintered. If the use of less than 20 parts by weight of the noble metal on the basis of 100 parts by weight of cermet, the conductivity of the heat generating portion is lowered, and when the amount exceeds 35 parts by weight, the amount of cermet is reduced and the heat resistance is lowered. This is because when used, the conductive paste is sintered at a high temperature, and the high temperature bonding property is lowered at the time of joining. When the content exceeds 55 parts by weight, the amount of the cermet and the precious metal is reduced, so that the conductivity and heat resistance are poor.

In addition, after forming the thick film type heating element, to form an electrode to supply the current to the heating element, the electrode material should be formed thick enough to accommodate the amount of current supplied to the thick film heating element, and should be a material that flows well current Specifically, platinum (Pt), gold (Au), silver (Ag) and alloys thereof may be used among the precious metals.

Then, the electrode is printed by a similar process to the heating element according to the present invention, it is preferable to be manufactured by sintering so that the current flows well by bonding at a high temperature (about 900 ~ 1,000 ℃).

In order to protect the thick film heating element from external impact and to electrically insulate, the insulation protective film is formed by heat treatment by printing molding on the thick film heating element. In this case, the insulating protective film is preferably formed by applying a solution containing 35-50 parts by weight of an insulating powder selected from the group consisting of alumina, aluminum nitride, and silica to 100 parts by weight of a silica sol or titania sol and heat-treating at 400 to 500 ° C. Do. The silica sol is used for the purpose of refractory and insulation and paste forming with other insulators, and the alumina and aluminum nitride are used to improve the fire resistance and heat resistance while assisting the silica component. If the amount is greater than the thickness, the coating of uniform thickness is not easy due to the viscosity of the paste, and if it is less than 35 parts by weight, the effect of the alumina or aluminum nitride or the viscosity control of the sol is not easy.

As described above, the present invention is characterized in that the hot plate includes a thick film type heating element including a substrate, a thick film type heating element, an electrode, and an insulating protective film. However, in the present invention, a structure based on the structure of the thick film-type heat generating unit and other materials may be added as necessary, and a structure in which some of the above-described structural structures are omitted may be possible.

On the other hand, in the present invention, if the substrate is made of stainless steel to form an insulating layer by coating a crystalline glass powder on the substrate for easy bonding and insulation with the heating element, then printing the thick film type heating element paste on the substrate, It is preferable to attach the heating element to the substrate by sintering it.

And, according to the method of the present invention, the electrode of the thick film-type heating unit is provided with a control unit and a control device for controlling the heating temperature by adjusting the amount of electrical energy to be converted into thermal energy by transferring the external electrical energy to the heating element. The hot plate is completed by connecting to the power supply.

Hereinafter, with reference to the accompanying drawings and examples preferred embodiments according to the present invention in detail as follows.

However, this is used for the purpose of illustrating the present invention, not intended to limit the scope of the present invention described in the meaning limitations or claims.

Therefore, it will be apparent to those skilled in the art that various modifications and equivalent other embodiments are possible.

As shown in Figs. 1 and 2, the hot plate of the present invention has a substrate 1 coated with an insulating substrate made of an insulating substrate or glass powder, and a thick film formed on the surface of the substrate to convert electrical energy into thermal energy. A heat generator 2, an electrode 3 for supplying electrical energy to the thick film heater 2 from the outside, and an insulating protective film 4 formed on the surface of the thick film heater 2 to electrically insulate the thick film heater. )

[Example]

In the present embodiment, a hot plate for cooking having a thick film-type heating part was manufactured on the plate-type heat resistant glass substrate 1 and the stainless steel 2 on which the insulating layer was formed using the following materials.

(1) When using a heat resistant glass substrate

The material of the thick film heating element 2 is a predetermined amount of organic material (PVB: poly vinyl Butyral) such that 100 parts by weight of conductive cermet, 30 parts by weight of silver (Ag) powder, and 45 parts by weight of crystallized glass powder are maintained in ink form suitable for printing. , A silicone antifoaming agent, a dispersant, a solvent, etc.) to prepare a thick film-type heating element paste, and the paste is printed on a stainless steel coated with heat-resistant tempered glass or crystallized glass powder, and dried and sintered to have a thick film thickness of 10 to A thick film-like heating element having a thickness of 20 µm was formed. At this time, the organic material used a commercial product according to a conventionally known method.

In addition, silver (Ag) was used as an electrode, and a solution in which alumina was mixed with silica sol was applied as a spraying method as an insulating protective film, and then sintered at 500 ° C. to prepare a hot plate prototype having a thick film-type heating part.

(2) In case of using stainless steel substrate with insulation layer

Crystallized glass powder was applied on stainless steel, and a prototype was prepared in the same manner as in the heat-resistant tempered glass substrate of Example (1).

Experimental Example

In this experiment example, the effect of the thick film type heating element was measured by measuring the power conversion efficiency of the prototype.

(1) glass substrate prototype

The prototype of the example had a size of 300 mm × 300 mm × 4 mm and a heating element area of 60 cm 2.

As a result, the available power corresponds to 18 to 25W per unit cm ² , thus, the power conversion efficiency is 98%.

 This can be seen that the power conversion efficiency of the conventional heater is much better than only 60% or less.

(2) stainless steel prototype

As a result of measuring the electrical characteristics, the watt density of 28W / ㎠ at 1300W was shown and the efficiency of the high-efficiency thick film heater was more than 98%. The power density of general nichrome and tungsten heating elements has a low value of 10 W / cm 2 or less.

Therefore, as described above, the conventional power conversion efficiency is only about 60% or less, but in the present invention is very good as about 98%, the thick film material used in the present invention is a cermet and air of a compound of ceramic and metal It is a mixture of noble metals that does not occur oxidation, unlike the conventional heat exchanger made of nichrome, tungsten, or molybdenum material, there is little change in resistance of the heating element according to the change of temperature, and thus temperature characteristics of the heating element are stable and precise adjustment is possible.

As described above, the hot plate of the present invention using the heat generating part in the form of a thick film has a lower manufacturing cost, lighter weight, and a shorter time taken to raise and lower the temperature than the conventional heater, thereby greatly reducing the waste of power.

In addition, the thin film heater of the present invention can be manufactured on the material that can be bent, the structure and shape of the heater is freely deformed, there is an effect that can greatly expand the performance and application range of the heater.

1 is a cross-sectional view of a hot plate with a thick film-type heating element according to a preferred embodiment of the present invention,

2 is a plan view of a hot plate with a thick-film heating element according to a preferred embodiment of the present invention.

3 is a perspective view of a hot plate provided with a thick-film heating element according to the present invention.

<Description of the symbols for the main parts of the drawings>

1: Substrate 2: Thick Film Heating Element

3: electrode 4: insulation protective film

Claims (4)

In the hot plate, A substrate made of heat resistant tempered glass or stainless steel; A thick film heating element formed by forming a thick film by sintering and attaching a conductive cermet and a paste including a precious metal and a glass powder selected from the group consisting of platinum, gold, silver and alloys thereof to one side of the substrate 1; And And a electrode connected to the heating element and supplying an external current to generate the heating element. The method of claim 1, The thick film-type heating element paste is a hot plate for cooking, characterized in that 100 parts by weight of the conductive cermet includes 20 to 35 parts by weight of noble metal and 45 to 55 parts by weight of glass powder. The method according to claim 1 or 2, Insulation formed by applying a solution containing 35 to 50 parts by weight of an insulating powder selected from the group consisting of alumina, aluminum nitride, and silica to 100 parts by weight of the silica sol or tinania sol on the thick film-type heating element and heat-treating at 400 to 500 ° C. A cooking hot plate, further comprising a protective film (4). The method of claim 1, Stainless steel substrate is a hot plate for cooking, characterized in that the glass powder is further coated by applying a glass powder.