JPH01159527A - Gas ignition plug and manufacture thereof - Google Patents

Abstract

PURPOSE:To omit a bonding process to reduce the manufacturing cost of the title plug by manufacturing an ignition plug for use in a gas burner by forming a porcelain using a crystal calcium phosphate glass powder and an alumina powder, and burning the same integrally with an electrode bar to fix the same. CONSTITUTION:The ignition plug 1 formed by an electrode bar 3, and a porcelain 2 which insulates and protects electrode bar 3, is manufactured by forming the porcelain 2 by use of a mixture of a crystal calcium phosphate glass powder and an alumina powder and burning the porcelain 2 integrally with the electrode bar 3 at a glass fusing temperature to fix the same. The porcelain 2 and the electrode bar 3 are integrally fixed to each other by insert molding or burning the porcelain 2 inserted with the electrode bar 3. As the glass powder, a crystal calcium phosphate glass is suitable. In order to impart, heat resistance and heat resisting antishock property to the same, a powder of ceramics such as zirconia, alumina and the like is mixed in the glass.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a spark plug used as an ignition device for a gas burner and a method for manufacturing the same. This relates to an insulator that is possible and has higher insulation resistance than conventional ones.

[Prior art] One method of igniting a gas burner is to use high-pressure discharge, and the spark plug used for this is FeC.
It consists of a r electrode rod and an insulator that insulates and protects it. Spark plugs were manufactured by using insulators made by molding and firing ceramic raw materials such as mullite and alumina, inserting electrode rods into the insulators, and fixing the electrode rods and insulators with adhesive.

[Problems to be solved by the invention] The conventional method of fixing the insulator and electrode rod with adhesive requires an adhesion process, and the adhesion process requires a lot of man-hours and is expensive, as well as restrictions on the shape of the spark plug. There is a problem in that the size of the shape is large, for example, L-shaped ones are difficult to manufacture.

The present invention was made to solve this problem, and its purpose is to reduce manufacturing costs by omitting the bonding process, and to provide a high-quality spark plug with high electrical insulation resistance and sufficient strength. The aim is to facilitate the manufacture of

[Means for Solving the Problem] In order to achieve the above object, the features of the present invention are as follows:
In a gas ignition plug formed of an electrode rod and an insulator that provides insulation protection for the electrode rod, the insulator is molded using a mixture of crystalline calcium phosphate glass powder and alumina powder, and is fired together with the electrode rod at a glass fusion temperature. The purpose is to fix the parts together.

[Function] Figures 1 and 2 show a spark plug sintered together by the method of the present invention.The insulator 2 and the electrode rod 3 are integrally formed by insert molding or by inserting the electrode rod into the insulator and firing it. is fixed to.

Conventionally, the firing temperature of ceramics used as insulators is a high temperature of 1200° C. or higher, so if the electrode rod and the insulator are fired together, the electrode rod will deteriorate due to heat.

Therefore, in order to obtain a gas ignition plug insulator that can be fired at 700°C or lower, has no cracks due to shrinkage during firing, and has sufficient insulation resistance and strength, the inventor of the present application conducted extensive research into the raw material composition and manufacturing method. We have developed a method in which a mixture of glassy powder and alumina powder is molded and fired at the glass fusing temperature.

As the glass powder, crystalline calcium phosphate glass is suitable. In order to add heat resistance and thermal shock resistance to this,
Zirconia (ZrO2), alumina (Al2) as necessary
Mix ceramic powder such as O3).

FIG. 4 shows the temperature characteristics of the insulation resistance of an insulator made of crystalline calcium phosphate glass to which zirconia and alumina are added and an insulator made of mullite.

It was found that the insulation resistance was significantly improved by adding about 16% by volume of alumina powder.

If the alumina powder is 20% by volume or more, sintering is difficult, and if the alumina addition is 12% by volume or less, the insulation resistance is equal to or lower than that of mullite.

When an insulator made by adding 16% by volume of alumina to calcium phosphate glass, molded and fired, is viewed under an electron microscope, it can be seen that the alumina component is incorporated into the calcium phosphate glass.

It is thought that when the firing temperature exceeds 600°C, the glass continues to soften, and at around 700°C, a crystallization reaction occurs at the interface between the Al2O3 particles and the wet glass.

When zirconia powder (ZrO2) is added instead of Al2O3, the ZrO2 particles do not react with the glass and are dispersed in the glass, so the insulation resistance of the insulator to which ZrO2 is added is hardly improved.

Ceramic powder and organic binder are mixed into the calcium phosphate glass powder as needed and thoroughly kneaded. Then, it can be fired as an insulator integrally formed with the electrode rod by injection molding or press molding. If the firing is performed at the glass fusion temperature, there will be no softening deformation, and even if there is an electrode rod that prevents shrinkage, the product will shrink while maintaining its plastic deformation characteristics, and no cracks will occur.

Further, in the method shown in FIG. 3, the inner diameter of the electrode rod insertion hole 4 of the insulator 2 is formed to be 5 to 15% larger than the outer diameter of the electrode rod 3, so that the electrode rod 3 can be easily inserted.

Since the insulator material generally shrinks by about 10 to 20% due to firing shrinkage, when an electrode rod is inserted into an insulator formed by injection molding or press molding and fired, a gas ignition plug is obtained in which the two are fixed together.

Next, the method of the present invention will be explained based on examples.

[Example 1] Calcium phosphate glass having a composition of 47CaO-lAl203.52P205 was melted, cooled and solidified, and then thoroughly ground to obtain a glass powder having a particle size of 1Oμ or less. Add 16% by volume of alumina (A1203) powder with a particle size of 1 l or less to this.
Then, 2% paraffin wax was added and thoroughly kneaded.

Using this raw material, the gas ignition plug 1 shown in FIG. 1 was formed by press molding. The cylindrical insulator 2 and the FeCr electrode rod 3 were integrally molded and fired at 700° C. for 2 hours. There were no cracks or other cracks in the insulator 2, the insulator was firmly fixed to the electrode rod, and there was no thermal deterioration of the electrode rod at all.

The temperature characteristics of the insulation resistance of this insulator are as shown in Figure 4, and it exceeded the insulation resistance of mullite in most temperature ranges.

[Example 2] 12% polystyrene was added to a mixture of calcium phosphate glass powder and 16% by volume alumina powder and thoroughly kneaded. Using this raw material, the L-shaped gas ignition plug 1 shown in FIG. 2 was formed by injection molding.

The electrode rod 3 is bent into an L-shape, and the electrode rod is inserted into the bent insulator 2 by injection molding.The obtained gas ignition plug 1 is degreased at 400°C, and then heated at 700°C. 2
Baked for an hour. There were no cracks or other cracks in the insulator, the insulator was firmly attached to the electrode rod, and there was no thermal deterioration of the electrode rod. The temperature characteristics of the insulation resistance of this insulator were exactly the same as in Example 1, and exceeded the insulation resistance of mullite.

[Comparative example] The same calcium phosphate glass powder as in Example 1 with a particle size of 1 p.
16% by volume of the following zirconia (Zr02) powder was added and mixed, and then 2% of paraffin wax was added and thoroughly kneaded.

Using this raw material, the gas ignition plug 1 shown in FIG. 1 was formed by press molding, and this was fired at 700° C. for 2 hours.

As shown in Figure 4, the temperature characteristics of the insulation resistance of this insulator were lower than the insulation resistance of mullite in all temperature ranges.

[Example 3] 16% by volume of alumina powder was added to crystalline calcium phosphate glass powder, and 5% of paraffin wax was added thereto and thoroughly mixed and kneaded. Then, the insulator 2 shown in FIG. 3 was press-molded. The inner diameter of the electrode rod insertion hole 4 is 2.2 mm.
It is. Insert the electrode rod 3 with an outer diameter of 2.0 mm into this, and
Firing was performed at 00°C for 2 hours. The spark plug 1 shown in FIG. 1 was obtained which had no cracks or deformation due to firing and had sufficient adhesion strength between the electrode rod 3 and the insulator 2. When this spark plug was tested, the dielectric strength voltage was 250,000 KV. In addition, it can withstand heat cycles from 00℃ to θ℃ in the thermal shock resistance test.
It was also confirmed that there was no deterioration in the conductivity of the electrode rod.

[Effects of the invention] By integrally sintering the insulator and electrode rod of a gas ignition plug using a raw material of calcium phosphate glass with alumina added, the temperature characteristics of insulation resistance are improved, and a good gas ignition plug without deformation cracks is obtained. is obtained.

Since the insulator and the electrode rod are fired and fixed together, the assembly process of fixing the electrode rod with adhesive is omitted, reducing costs. Further, excellent effects such as low firing temperature and reduced energy costs can also be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a cylindrical gas spark plug. FIG. 2 is a cross-sectional view of an L-shaped gas ignition plug, FIG. 3 is a perspective view showing the electrode rod inserted into an insulator having an inner diameter larger than the outer diameter of the electrode rod, and FIG. 4 is a cross-sectional view of the L-shaped gas ignition plug. 3 is a graph showing insulation resistance in a high temperature range of insulators according to No. 3 and Comparative Example. In the figure, numeral 2 indicates an insulator, and 3 indicates an electrode rod.

Claims (1)

[Scope of Claims] 1) A gas ignition plug consisting of an electrode rod and an insulator for insulating and protecting the same, wherein the insulator is made of a mixture of crystalline calcium phosphate glass powder and alumina powder. . 2) A method for manufacturing a gas ignition plug consisting of an electrode rod and an insulator that provides insulation protection for the electrode rod, in which the electrode rod is integrally insert-molded into a mixture whose main component is glassy powder, which serves as the insulator, and then the glass is fused. A method for manufacturing a gas spark plug characterized by firing at a certain temperature. 3) A method for manufacturing a gas ignition plug consisting of an electrode rod and an insulator for insulating and protecting the electrode rod, the inner diameter of the electrode rod insertion hole of a mixture whose main component is vitreous powder serving as the insulator is 5 mm from the outer diameter of the electrode rod. A gas ignition plug characterized in that the electrode rod is molded to a size of ~15%, then the electrode rod is inserted into the electrode rod insertion hole and fired, and the mixture as an insulator and the electrode rod are integrated by firing shrinkage. Production method. 4) The method for manufacturing a gas ignition plug according to claim 2 or 3, wherein the vitreous material is crystalline calcium phosphate glass.