JPH0552641B2 - - Google Patents

Description

[Detailed description of the invention]

[Field] The present invention relates to a resistor composition for a resistor-containing spark plug. [Prior Art] Conventionally, in order to stabilize the load life characteristics of a resistor composition of a spark plug, for example, in electrical aging to electrically stabilize the resistor composition, aqueous solution was used to counteract the decrease in resistance value caused by the addition of carbon black. Adding carbonaceous substances
22505), addition of metal oxides and carbides of groups A and A of the periodic table to glass-aggregate-carbon resistance materials (Japanese Patent Publication No. 19721). As the output increases, the spark discharge energy also increases, and in conventional resistor compositions, the carbon contained in the living organisms in the resistor composition is oxidized (burned out) due to the current energy of the spark discharge flowing through the resistor during use. and the resistance value increases. For this reason, adding a large amount of a load life stabilizing material (such as TiO ₂ ) improves the load life characteristics, but the temperature coefficient of resistance deteriorates, resulting in deterioration of radio noise characteristics. Also special public service 56-51142
and Japanese Patent Publication No. 57-60761, it consists of glass-metal oxide and carbide (load life stabilizer)-carbon-metal powder or alloy powder. A self-sealing glassy resistor composition is disclosed.
However, since this self-sealing glass resistor composition does not contain aggregate or ceramic powder, it has poor stability in resistance value and poor radio noise prevention effect, and as engines have become more powerful in recent years. However, it has not been possible to obtain a resistor composition that is fully satisfactory against the increase in spark discharge energy. [Object of the Invention] An object of the present invention is to provide a resistor composition for a resistor-containing spark plug that has sufficient load life stability against the increase in spark discharge energy accompanying the recent increase in engine output. be. [Structure of the Invention] The resistor composition for a resistor-containing spark plug of the present invention contains 100 parts by weight of a basic mixture consisting of 30 to 70% by weight glass and the balance being inorganic aggregate, and TiO ₂ , ThO ₂ , ZrO ₂ , Nb ₂ O. _Five ,
Oxides such as Ta ₂ O ₅ , Cr ₂ O ₃ , La ₂ O ₃ , MgO, ZnO, TiC, VC, NbC, TaC, Cr ₃ C ₂ , Mo ₂ C,
Carbides such as WC, LaC ₂ , B ₄ C, SiC, TiB,
One or more types of load life stabilizer such as TiN 0~
30 parts by weight, 0.1 to 10 parts by weight of a resistance value adjusting material made of carbon black or an organic carbonaceous material or a combination of both, Al, Mg, Ti, Zr, Ga,
Metal powder consisting of one or more types of Ag metals 0.01~10
It consists of parts by weight. [Effects of the Invention] In the resistor composition for a resistor-containing spark plug of the present invention having the above-mentioned structure, the carbon in the resistor component is oxidized due to the increase in spark discharge energy accompanying the increase in engine output in recent years. The increase in resistance value caused by burnout is prevented by adding metal powder with a relatively strong reducing action, and the stability of the resistance value is sufficiently satisfied over a long period of time. [Example] The present invention will be described in detail below. Glass, such as borosilicate glass, barium borate glass, lead glass, etc., is used as the binder for the spark plug resistor. In particular, BaO-containing glass has excellent wettability with carbonaceous substances. The softening point of the glass is preferably higher than about 300°C. If the softening point becomes too low, problems such as difficulty in holding the electrode rod and terminal rod firmly and fluctuations in resistance occur when used in an actual engine. The glass used in the present invention is prepared by a known method, ground into a suitable fine powder, and fritted before use. In the present invention, the composition of the basic mixture (glass+mineral aggregate) in the total mineral component is 30-70% by weight of glass. If it is less than 30%, the adhesion of the aggregate will be insufficient and the resistor will become porous, resulting in poor airtightness and load life characteristics, as well as difficulty in press-fitting the terminal rod (male thread), and Difficulties also arise in the strength of the bond with the wall surface. On the other hand, if the glass content exceeds 70%, the glass will penetrate between the carbon particles that act as a conductive material, resulting in a large increase in resistance value, and the variation in resistance value. The body is not compressed and filled with a plane perpendicular to the long axis of the central hole, but is filled with a concave or convex spherical shape on both the upper and lower end surfaces, and the effective length of the resistor becomes shorter than the designed value. It becomes difficult to obtain a resistance value of 1, and the noise prevention effect is also inferior. Inorganic aggregates include alumina, zircon, mullite,
Contains crystalline or amorphous oxides and silicate minerals that are commonly used as raw materials for ceramics such as fused silica, magnesia, silica, and clay;
Contains heat-resistant powder material that is a poor electrical conductor. In addition to the above, the inorganic aggregate preferably contains at least one nitride such as silicon nitride, boron nitride, and aluminum nitride. These inorganic aggregates are added for the purpose of imparting heat resistance to the resistor and preventing spherical formation.
In particular, adding 0.1% by weight or more of the above nitrides is useful for further enhancing the noise prevention effect. As is well known, in addition to the above-mentioned basic mixture, the resistor contains a predetermined amount of a single substance (carbon black, acetylene black, graphite, pitch powder, or other organic substance that can be carbonized during sintering) in order to adjust the resistance value. The carbon material is the basic mixture in terms of carbon.
0.1 to 10% by weight (preferably 0.5% by weight per 100 parts by weight)
~3% by weight). In general, carbonaceous materials have an excessive resistance value when less than 0.1% by weight, and 10% by weight or less.
On the other hand, if it exceeds this value, the resistance value decreases and is no longer useful for noise prevention. The organic substance that can be carbonized during sintering preferably also serves as a binder for the resistor powder composition, and for this purpose, known organic caking substances are commonly used. For example, dextrin, CMC, methylcellulose,
Water-soluble organic binders such as glycerin, sucrose, lactose, maltose, glucose, xylose, PVA or lubricating binders such as paraffin wax can be used for this purpose. The resistor composition for a resistor-containing spark plug of the present invention further has a resistance value load life characteristic (stability over time of resistance value during use) stabilizer (load It is preferable to use a resistance stabilizer). This stabilizing material was published in 1983.
It is the same as the stabilizer to be added to the conductive glass sealing material disclosed in No. 27985, for example,
_TiO2 , _ThO2 , _{ZrO2 , Nb2O5 , Ta2O5} , _{Cr2O3 ,}
Oxides such as La ₂ O ₃ , MgO, ZnO, TiC, VC,
NbC, TaC, _{Cr3C2 , Mo2C} , WC, _LaC2 , _B4C ,
The present inventor reported in Japanese Patent Application Laid-Open No. 50-27983 that a similar effect can be obtained by using carbides such as SiC, and one or more of TiB, TiN, etc., and adding them to the resistor itself. , confirmed in Japanese Patent Application Laid-Open No. 50-27984. However, even when this stabilizer is used, the amount of glass in the basic mixture is relative to the total resistor inorganic component.
It is desirable that the content is 30% by weight or more. Metal powder is a spark discharge current flowing through a resistor,
Al, Mg, Ti, Zr,
One or more metals such as Ga and Ag are added in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the base material, but if more than 10 parts by weight is added, the resistance value decreases too much and the noise prevention effect deteriorates. do. Next, glass having the composition shown in Table 1, aggregate,
A resistor composition consisting of a raw material combination of load life stabilizing material, metal powder, and resistance value adjusting material was prepared as shown in Table 2, and pulverized and mixed in a whole mill for 3 hours.
A center electrode is inserted into the lower end of the center shaft hole of the alumina insulator, and 0.2 g of the conductive sealing material, 0.5 g of the above-mentioned pulverized and mixed resistor composition, and 0.2 g of the conductive sealing material are sequentially filled thereon. Then, a terminal electrode was inserted into the shaft hole. Next, this whole insulator is 850
Heat to ~950℃ and apply pressure (40Kg) from the terminal electrode side.
was added, and the resistor composition filled in the shaft hole and the conductive sealing material were sealed by hot heating. A housing with a grounding electrode fixed to the outer periphery of this insulator is fixed to the 0.5 to 30kΩ required for radio noise suppression.
A spark plug containing a resistor with a resistance value within the range of was obtained. In the present invention, in order to verify load life stability, an automotive transistor ignition device was used, and the stored energy on the primary side of the ignition coil was 100 millijoules,
Under the conditions of discharge voltage 30kv and number of discharges 3600 times/min.
Rate of change in resistance value after 100 hours of operation (average of 10 values)
The results shown in Table 2 were obtained.

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【table】

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Claims (1)

[Claims] 1 100 parts by weight of a basic mixture consisting of 30 to 70% by weight glass and the balance inorganic aggregate, TiO ₂ , ThO ₂ , ZrO ₂ ,
Oxides such as Nb ₂ O ₅ , Ta ₂ O ₅ , Cr ₂ O ₃ , La ₂ O ₃ , MgO, ZnO, TiC, VC, NbC, TaC, Cr ₃ C ₂ ,
Carbides such as _Mo2C , WC, _LaC2 , _B4C , SiC,
and 0 to 30 parts by weight of one or more load life stabilizers such as TiB, TiN, etc., 0.1 to 10 parts by weight of a resistance value adjusting material made of carbon black or an organic carbonaceous material or a combination of both, Al, Mg, Ti,
Metal powder made of one or more of Zr, Ga, Ag metals
A resistor composition for a resistor-containing spark plug, comprising 0.01 to 10 parts by weight.