KR100644319B1 - Spark Plug with Iridium-Rhodium Alloy Electrode Tip including Tungsten - Google Patents

Abstract

The present invention relates to an ignition plug, and more particularly, to improve ignition by bonding an ignition part of a noble metal material to a center electrode and a ground electrode, respectively, and adding a certain amount of elements to the ignition part to improve volatility of iridium. The present invention relates to an iridium-rhodium-based spark plug containing tungsten capable of increasing durability and of increasing heat resistance and abrasion resistance.

The present invention for this purpose; A ground electrode facing the center electrode to form a gap capable of generating a spark; And ignition parts of a precious metal material bonded to the center electrode and the ground electrode, respectively, wherein the ignition parts include 20 wt% rhodium (Rh), 10 wt% tungsten (W), and 1 wt% ruthenium (Ru). ), And the rest is made of an alloy composed of iridium (Ir).

Ignition, Iridium, Elemental, Durable

Description

Spark Plug with Iridium-Rhodium Alloy Electrode Tip including Tungsten}

1 is a partial cross-sectional view showing a spark plug according to the present invention,

2 is an exemplary view showing the durability test form of the spark plug;

3 is a graph showing the amount of tungsten and the amount of void increase in the spark plug.

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

10: center electrode 10a, 20a: ignition unit

20: ground electrode 50: spark plug

The present invention relates to an ignition plug, and more particularly, to improve ignition by bonding an ignition part of a noble metal material to a center electrode and a ground electrode, respectively, and adding a certain amount of elements to the ignition part to improve volatility of iridium. The present invention relates to an iridium-rhodium-based spark plug containing tungsten capable of increasing durability and of increasing heat resistance and abrasion resistance.

In recent years, due to urban air pollution and global warming caused by CO, problems such as automobile exhaust emission reduction, fuel efficiency improvement, and NO reduction have emerged.

Therefore, the development of an ignition device that can reduce the generation of pollutants and improve fuel efficiency in the automobile industry has been actively progressed.

The core of the ignition device is a spark plug, which is a component for generating a spark capable of burning a mixer in a cylinder of an automobile engine.

In order to improve the performance of the spark plug, high ignition and low discharge voltage are required.

In addition, the spark plug continuously causes sparks in an environment of high temperature and high pressure, and requires a long life with high performance, and for this purpose, it is necessary to improve durability.

In order to solve this problem, the tip of the precious metal material was welded to the center electrode and the ground electrode of the spark plug.

Initially, the tip consisted mainly of platinum, which caused difficulty in thinning the electrode due to the wear problem as well as the high price of platinum. Therefore, an iridium (Ir) alloy has been proposed as an alternative, which has the advantages of lower cost than platinum, excellent wear resistance and idling stability, low discharge voltage, and low NO emission.

However, pure iridium (Ir) has a disadvantage in that the volume loss of the electrode tip is large due to volatilization between 900 and 1200 ° C.

On the other hand, recently, in order to improve the volatilization phenomenon of pure iridium (Ir) as described above in high temperature environment, rhodium (Rh) is added to iridium (Ir) to form a RhO film, thereby suppressing the formation of IrO having a large vapor pressure to prevent oxidation. Methods to improve volatility have been developed.

Therefore, when rhodium (Rh) is added to pure iridium (Ir) as described above, the oxidation resistance of the iridium (Ir) -rhodium (Rh) alloy is improved as the amount of rhodium (Rh) is increased, but the rhodium (Rh) As the addition amount increased, the melting point of the alloy was reduced, resulting in a decrease in durability.

The present invention has been made to solve the above problems, an object of the present invention is to provide a spark plug that can increase the durability, heat resistance and wear resistance while maintaining high ignition.

In addition, another object of the present invention is to provide a spark plug that can reduce the diameter of the discharge portion to reduce the required voltage during discharge, idling stability and the like.

The present invention for achieving the above object and the center electrode; A ground electrode facing the center electrode to form a gap capable of generating a spark; And ignition parts of a precious metal material bonded to the center electrode and the ground electrode, respectively, wherein the ignition parts include 20 wt% rhodium (Rh), 10 wt% tungsten (W), and 1 wt% ruthenium (Ru). ), And the rest is made of an alloy composed of iridium (Ir).

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The present invention having the features as described above will be more clearly described through the preferred embodiment accordingly.

Hereinafter, preferred embodiments of the present invention will be described in detail with the accompanying drawings.

1 is a partial cross-sectional view showing a spark plug according to the present invention.

As shown in FIG. 1, the spark plug 50 according to the present invention includes a center electrode 10 and a ground electrode 20 extending smoothly at a position opposite to the front end of the center electrode 10.

Here, the ground electrode 20 is opposed to the center electrode 10 to form a gap capable of generating a spark.

The center electrode 10 and the ground electrode 20 are preferably made of an alloy containing Ni as a main component to have high heat resistance and wear resistance.

In addition, the ignition parts 10a and 20a of the precious metal material are joined to the front end portions of the center electrode 10 and the ground electrode 20, respectively.

Here, the ignition parts 10a and 20a may be preferably bonded to the center electrode 10 and the ground electrode 20 by welding, and more preferably, may be bonded by laser welding.

According to the above, the ignition parts 10a and 20a are bonded to the center electrode 10 and the ground electrode 20, respectively, and the ignition parts 10a and 20a form a spark gap therebetween.

Therefore, in the spark plug 50 according to the present invention, the physical and chemical properties of the ignition parts 10a and 20a are very important, which is the kind and content of elements contained in the alloy constituting the ignition parts 10a and 20a. According to the bar, the experiments performed by the applicant and the results are as follows.

Experimental Method

Spark plug 50 The material of the ignition sections 10a and 20a is based on iridium (Ir), the amount of rhodium (Rh) is 0-30% by weight, the amount of ruthenium (Ru) 0-5% by weight, tungsten The amount of (W) was varied from 0 to 30% by weight, added, and then melted. The core electrode 10 was prepared in the form of a rod with a diameter of 0.7 mm through a process such as forging, rolling, and drawing at a high temperature. ), Where 0% means no addition.

At this time, the diameter of the center electrode 10 is 0.7mm, the height is 1.12mm, the diameter of the ground electrode 20 is 1.4mm, the height is 0.15mm.

Heat cycle endurance tests were conducted on engine dynamometers for specimens of each composition prepared in this manner.

The experiment was carried out for 300 hours (600 cycles) at a rotation speed of 6000rpm in a four-cylinder 1600 ℃ gasoline engine, where one cycle was 30 minutes, and the heating and cooling were as follows.

2 is an exemplary view showing the durability test form of the spark plug.

As shown in FIG. 2, one cycle is divided into three stages, and in the first stage, the engine is operated for a total of three minutes, including 10 seconds of time when the engine reaches idle at 6000 rpm from idling.

Again, the engine is stopped for 2 minutes, including 10 seconds of idle time at 6000 rpm.

In the first step by repeating the above process, the engine operates a total of four times at 6000rpm.

In the second stage, the engine is stopped for 10 minutes including the time 30 seconds when the engine is stopped through the idling from 6000 rpm.

In addition, in the third step, the stopped engine is rapidly cooled for 2 minutes using cooling water.

By the above experiment, the degree of wear of the ignition parts 10a and 20a bonded to the center electrode 10 and the ground electrode 20, respectively, is measured, which is referred to as a gap between the ignition parts 10a and 20a (hereinafter, referred to as a gap). It becomes possible by measuring

That is, the degree of wear of the voids and the ignition parts 10a and 20a is in a proportional relationship.

Therefore, if the increase of the voids is large, the durability and abrasion resistance of the ignition unit 10a, 20a is low, and if the increase of the voids means that the durability and wear resistance of the ignition unit 10a, 20a is high.

<Experiment Result>

<The result showing the constituents of the ignition part and the increase amount of the voids> No Ignition Component Increase in voids One Ir 100wt%  0.28 2 Ir-10wt% Rh 0.2 3 Ir-20wt% Rh  0.18 4 Ir-30wt% Rh  0.22 5 Ir-20wt% Rh-0.5wt% Ru  0.13 6 Ir-20wt% Rh-1wt% Ru  0.11 7 Ir-20wt% Rh-3wt% Ru  0.12 8 Ir-20wt% Rh-5wt% Ru  0.14 9 Ir-20wt% Rh-1wt% Ru-1wt% W  0.12 10 Ir-20wt% Rh-1wt% Ru-5wt% W  0.09 11 Ir-20wt% Rh-1wt% Ru-10wt% W  0.08 12 Ir-20wt% Rh-1wt% Ru-15wt% W 0.1 13 Ir-20wt% Rh-1wt% Ru-20wt% W  0.13 14 Ir-20wt% Rh-1wt% Ru-25wt% W  0.15 15 Ir-20wt% Rh-1wt% Ru-30wt% W  0.18

Table 1 shows the relationship between the amount of each element constituting the ignition unit and the increase amount of the voids.

As can be seen from Table 1, when the 20% by weight of rhodium (Rh) is added to the element of iridium (Ir), the amount of increase in voids is the smallest, the ignition part 10a, 20a of the spark plug 50 according to the present invention. ) Preferably contains 20% by weight of rhodium (Rh).

For reference, when rhodium (Rh) is added to the iridium (Ir) element in the ignition units 10a and 20a, oxidation volatility at the high temperature of the iridium (Ir) is improved, and thus the ignition units 10a and 20a Durability is improved. However, when the amount of rhodium (Rh) is added less than 10% by weight, the durability improvement effect of the ignition unit (10a, 20a) is insignificant, while when the amount of rhodium (Rh) is added more than 30% by weight, Rather, there is a problem that the durability of the ignition unit (10a, 20a) is reduced.

In addition, it can be seen that when the ruthenium (Ru) is added to the ignition parts 10a and 20a containing 20% by weight of rhodium (Rh) in the iridium (Ir) element, the increase in the amount of voids is further reduced. This is attributed to the addition of high melting point ruthenium (Ru) (melting point 2334 ° C) to the ignition sections 10a and 20a, thereby improving heat resistance and wear resistance.

At this time, the amount of ruthenium (Ru) contained in the ignition unit (10a, 20a) is preferably in the range of 0.5% by weight to 5% by weight, which is of the ruthenium (Ru) contained in the ignition unit (10a, 20a) If the amount is less than 0.5% by weight, the durability improvement effect of the ignition unit (10a, 20a) is insignificant, while if the amount of ruthenium (Ru) is more than 5% by weight rather the durability of the ignition unit (10a, 20a) This is due to the degradation.

Furthermore, the amount of ruthenium Ru contained in the ignition parts 10a and 20a in the spark plug 50 according to the present invention is more preferably 1% by weight.

In addition, by adding the high melting point tungsten (W) (melting point 3422 ° C) to the ignition unit 10a and 20a, heat resistance and abrasion resistance can be further improved. In this case, the amount of tungsten is 1% by weight to 30%. It is limited to the range of weight%.

When the amount of tungsten (W) is less than 1% by weight, it is difficult to expect durability improvement of the ignition parts 10a and 20a, and when the amount of the tungsten (W) exceeds 30% by weight, the durability of the ignition parts 10a and 20a is rather high. This is because a negative effect occurs, such as lowering or poor ignition in the ignition units 10a and 20a.

3 is a graph showing the amount of tungsten (W) and the amount of increase in the pore of the spark plug 50. In the spark plug 50 according to the present invention as shown in FIG. It is good.

And, more preferably, the amount of tungsten (W) is preferably in the range of 5% by weight to 15% by weight.

Furthermore, as shown in the above table, the amount of tungsten (W) contained in the ignition sections 10a and 20a is more preferably 10% by weight.

As described above, in the spark plug 50 according to the present invention, at least one of the ignition parts 10a and 20a of the precious metal material, which are respectively bonded to the center electrode 10 and the ground electrode 20, that is, the center electrode 10. And the ignition unit 10a on the side of the center electrode 10 or the ignition unit on the ground electrode 20 side, which are both of the ignition units 10a and 20a joined to both sides of the ground electrode 20, or any one of them. 20a) is composed of an alloy containing rhodium (Rh), ruthenium (Ru), and tungsten (W) in iridium (Ir), where 20 wt% of rhodium (Ru) and 1 wt% of the respective elements are contained. Ruthenium (Ru) and 10% by weight of tungsten (W) is contained, the remainder is most preferably composed of iridium (Ir).

As described above, the present invention improves the ignition property by bonding the ignition part of the precious metal material to the center electrode and the ground electrode, respectively, and by adding a certain amount of elements to the ignition part to improve the volatility of iridium, thereby increasing the durability of the ignition part. Of course, there is an effect that can increase the heat resistance and wear resistance.

Furthermore, the present invention has the effect of reducing the diameter of the discharge portion by improving the durability, heat resistance, wear resistance of the ignition portion, thereby reducing the required voltage for discharge, idling stability and the like.

Claims (6)

A center electrode 10; A ground electrode 20 facing the center electrode 10 to form a gap capable of generating a spark; And ignition parts 10a and 20a of precious metal materials respectively bonded to the center electrode 10 and the ground electrode 20. The ignition parts 10a and 20a may include 20 wt% rhodium (Rh) and An iridium-rhodium-based spark plug containing tungsten, wherein 10% by weight of tungsten (W) and 1% by weight of ruthenium (Ru) are contained, and the remainder is composed of an alloy composed of iridium (Ir). delete delete delete delete delete

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