JPS63257193A - Ignition plug - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a spark plug for an ignition bladder for an internal combustion engine, and particularly to a spark plug whose electrode has improved resistance to spark consumption.

(Prior Art) In recent years, as the performance of internal combustion engines has improved, there has been an increasing demand for long-life spark plugs with excellent spark wear resistance from the viewpoint of maintenance requirements. In order to extend the life of spark plugs, it has been well known that the center electrode is made of a heat-resistant, corrosion-resistant metal material such as a Ni alloy, and precious metals are used in the spark discharge portion of the outer electrode.
It has been proposed to use rod-shaped chips or thin plate chips made of noble metal materials, mainly Pt and Pt-gold alloys, by joining them by electric resistance welding or laser welding. However, the former method requires a large amount of expensive precious metal materials, resulting in high costs, while the latter method involves punching disk-shaped chips from precious metal plates and joining them, so there are many parts other than the chips, and the yield is 30%.
96 is also worsening and becoming a factor in high costs. te especially the 6th
As shown in the figure, as the amount of Ir added increases, the spark wear resistance of P and Ir alloys can be improved. The Ir addition amount is 20 to 25% by weight, which is the limit for thin plate forming processing. Therefore, Ir alloys containing P with 25% Ir added, pure Ir materials, etc. have good spark wear resistance. The feet also have the disadvantage that they cannot be used as spark plug electrode tips.

(Problems to be Solved by the Invention) The present invention is intended to improve the above-mentioned drawbacks, and is capable of mass production without wasting precious metals, reducing costs, and is resistant to spark consumption, which makes chip forming difficult depending on the melting method. The aim is to extend the life of the plug by using a noble metal material with excellent properties as the tip of the spark discharge part.

(Additional means and effects for solving the problem) The present invention has at least a pair of opposing center tta and outer electrodes,
The spark plug is made by discharging a spark between these electrodes, and the electrode is made of a Ni-based alloy base material, and at least 75% of the spark discharge part of at least one of the electrodes is made of Ir powder or Pt powder based on Ir powder. It is made by joining chips obtained by sintering a mixed powder with addition of % by weight, and as mentioned above, it is possible to use P with a large amount of Ir added as an Ir-based alloy and pure Ir as a chip, which has excellent spark wear resistance. Therefore, the life of the plug can be easily extended, and there is no wastage of material in chip processing, which allows mass production and reduces costs.

(Example) Hereinafter, the present invention will be explained by examples.

FIG. 1 shows one embodiment of a typical ignition bladder of the present invention, in which 1 is made of Ni-8i-- which has heat and corrosion resistance.
Mn-Cr *N to Cr-Fe (Incone/L/)
The center electrode is made of a Ni-based alloy such as, and usually has a Cu core sealed inside to increase its thermal conductivity.

2 is an insulator made of high alumina porcelain or the like, and the center electrode 1 is inserted into the shaft hole of the insulator made of conductive glass 3. It is sealed together with the terminal electrode 5 via the resistor 4. Reference numeral 6 denotes a companion metal fitting having an engine mounting screw 6a, and the insulator 2 is disposed in its inner cavity, and its upper end periphery 6b is fixed by known caulking. Reference numeral 7 denotes a friendly electrode which is joined to the annular end surface 6c of the metal shell 6, and is made of the same Ni-based alloy as the center ti, and its tip inner surface faces the tip surface of the center WL pole 1 to form a spark gap. 8 and is a fixed spark plug.

This invention includes a spark discharge portion at the tip of the center electrode 1 and an outer Y
A noble metal tip 9 is formed in a spark discharge portion on the inner surface of the tip of the l pole 7. The noble metal chip material used here is Ir.
KPt is added up to 76% by weight at most, and microchips are formed by powder metallurgy, and the amount of Ir added.

The sintering temperature may be gradually increased as the sintering temperature increases.

In powder metallurgy, Ir powder and Pt powder are mixed with an organic solvent, granulated, press-molded into a predetermined chip shape, and then subjected to calcination and final firing to produce chips. If a dense sintered body close to the theoretical density cannot be obtained, HIP (
It is recommended to perform hot isostatic pressing. The tip 9 formed in this way is joined to the spark discharge part of the center electrode and/or the outer electrode of the spark plug by electric resistance welding or ultrasonic welding, respectively, and after joining, it can be attached to the spark discharge part of the center electrode and/or the outer electrode, respectively, depending on the purpose. Heat treatment may be performed before forming the alloy layer.

Furthermore, the mixing ratio of Ir powder and Pt powder is
The mixing ratio may be selected within the above range depending on the purpose using the outer electrode.

In addition, as shown in FIG. 3, the shape of the chip 9 can be arbitrarily designed and used in various shapes such as a round shape, an elliptical shape, a circular shape with a flange, a donut shape, etc., which are characteristic of powder metallurgy. Its thickness H is 0.05 to 1. Off and 0
．． 05Jff and below consists of powder pressing. Furthermore, the tip outer diameter is Q, 5 ff -1,51! R, and due to the capacity of the press mold, Q, it is impossible to lower than 5 srs, and
'C1,5f1 or higher is unnecessary because it has excellent spark wear resistance.

4 and 5 show other embodiments of the present invention,
A spark plug in which a noble metal tip 10 of the present invention is formed at the tip of a central type i1, and a spark gap 8 is formed by arranging the tip inner surfaces of a plurality of outer electrodes 7 to face the tip circumference F & 10a of the tip 10. As shown in FIGS. 4 and 5, a creeping gap 11 is provided between the tip 10 of the center electrode 1 and the outer electrode 7 along the circumferential side of the tip of the firing part of the insulator 2. It is also applied to spark plugs. Although the spark wear resistance can be improved by providing a plurality of outer electrodes, if necessary, the noble metal tip of the present invention may also be formed on the outer electrode side as in the above embodiment.

Next, in the spark plug of the embodiment shown in FIG.
After forming Ir alloy chips containing 50% by weight of Pt as tips for pole 1 and outer electrode 7 by ultrasonic welding,
Heat treated at 000'C for 1 hour and using 9 spark plugs, 5500rprn
A 200-hour durability test was conducted under the conditions of No abnormality was observed.

(Effects of the Invention) As described above, the spark plug of the present invention is made by forming an Ir-based Pt-Ir alloy using powder metallurgy, which was considered difficult to process, and has excellent spark durability and a long service life. In addition, since it is formed using powder metallurgy, there is no wastage of materials, making it suitable for mass production and reducing costs.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a spark plug showing an embodiment of the present invention, FIG. 2 is an enlarged partial sectional view of the ignition part of FIG. 1, FIG. 3 is a perspective view showing the shape of the tip, 5 and 5 are enlarged partial sectional views of the ignition part showing other embodiments of the present invention, and FIG. 6 is a graph showing the relationship between D addition and spark consumption. 1...Center f/ i-pole 7...Outer pole Pole...Spark gap 9.10...Natpu patent applicant NGK SPARK PLUG CO., LTD. Representative Takashi Imai Fig. 1 Fig. 82 [Fig. 13 Fig. 4

Claims (2)

[Claims] (1) In a spark plug that has at least a pair of opposing center electrodes and an outer electrode, and is configured to cause a spark discharge between these electrodes, the electrode is made of a base material of a Ni-based alloy, and at least one of the spark discharge parts , Ir powder or Ir
A spark plug characterized in that a chip obtained by sintering a mixed powder containing powder as a base and adding at most 75% by weight of Pt powder is bonded. (2) The size of the above chip is 0.5mm≦D≦1.5mm, 0.05mm≦H, where the diameter is D and the thickness is H.
Claim 1 set in the range of ≦1.0 mm
Spark plugs listed in section.