JP2002359053A - Composite electrode material for ignition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite electrode material for ignition superior in ignitability and durability even at a high temperature, and superior in workability. SOLUTION: A plate-like covering material of a Pt alloy is laminated at least on one surface of the obverse and the reverse in a plate-like base material of Ir or an alloy rich in the Ir, and is rolled and formed as a thin plate material by hot working. The disk-like electrode material is formed by performing press blanking on this thin plate material. This electrode material is jointed to a central electrode of a spark plug, and is used as a discharge part of the central electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composite material for ignition used in a spark plug for an internal combustion engine.

[0002]

2. Description of the Related Art FIG. 5 shows an example of this type of spark plug. Reference numeral 1 denotes a terminal portion, which is fitted with a plug cord (not shown) and receives a high voltage. 2 is
An insulator that holds and insulates the supplied high voltage.
Reference numeral 3 denotes a mounting portion that is mounted to a combustion chamber of an internal combustion engine using a screw portion 4 via a gasket (not shown).

[0005] Reference numeral 5 denotes a side electrode, which is electrically connected to the mounting portion 3, connected to the main body of the internal combustion engine via the screw portion 4 and grounded. Reference numeral 6 denotes a center electrode, which is electrically connected inside the terminal portion 1 and the insulator 2, forms a spark gap between the terminal portion 1 and the side electrode 5, and constitutes a firing electrode portion. In the spark plug having such a configuration, the high voltage generated by the ignition coil is applied to the terminal portion 1, the high voltage is held by the insulator 2, and the center electrode connected inside the insulator 2 is connected. It is led to 6.

On the other hand, the lateral electrode 5 is
, An ignition spark occurs in a spark gap formed by the center electrode 6 and the side electrode 5 to which a high voltage is applied. The ignition spark ignites the compressed air-fuel mixture in the combustion chamber of the internal combustion engine. As a material of the center electrode 6 and the side electrodes 5 used in such a high temperature environment, generally, Pt which is excellent in oxidation resistance, is useful for improving spark consumption resistance and improving combustion efficiency is used. And I
An alloy containing r as a main element is used.

[0005]

However, in the above-mentioned conventional materials, the temperature in the combustion chamber increases with the recent improvement in the performance of the internal combustion engine, and the ignition electrode portion of the spark plug is heated to a higher temperature than ever. Since Pt or a Pt alloy is used for the ignition electrode portion, the electrode is easily consumed due to the sputtering by the ignition spark. In addition, when Ir or an Ir alloy is used, oxidation and volatilization at a high temperature become remarkable, and there is a problem that the electrode is easily consumed similarly to the case of Pt.

[0006] In addition, if Pt and Ir are alloyed only to eliminate sputtering and oxidative volatilization at a high temperature, which are the causes of electrode consumption, the oxidation resistance, which is a characteristic of a Pt alloy, and the characteristic of Ir However, there is a problem that both the melting point and the high melting point are impaired. Furthermore, Ir or an alloy rich in Ir has a problem that processing into a plate shape is difficult because of extremely poor workability.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a composite electrode material for ignition excellent in ignitability and durability and excellent in workability.

[0008]

In order to solve the above-mentioned problems, the present invention secures arc resistance by using Ir or an Ir alloy as a base material, and mounts a Pt alloy on at least one of the front and back surfaces thereof. In addition, wear resistance is improved by the synergistic effect of these alloys, and workability is also improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the composite electrode material for ignition according to the present invention will be described below with reference to the drawings. FIGS. 1A and 1B are perspective views showing an embodiment of the present invention. 2 and 3 show application examples of the present invention.

The same parts as those in the conventional configuration are denoted by the same reference numerals, and description thereof will be omitted. 11 is a substrate,
r or an alloy rich in Ir. 12 is
It is a coating material and is made of a Pt alloy. Next, the operation of the above-described first embodiment will be described. A plate-like base material 11 made of Ir or an alloy rich in Ir is combined with a plate-like Pt alloy coating material 12 on both front and back surfaces thereof, and is rolled into a thin sheet material by hot working and formed. An electrode material 13 as shown in FIG. 1A is formed by making this thin plate material into a disk shape by press punching.

FIG. 1B shows an electrode material 13 formed by combining a plate-shaped base material 11 with a plate-shaped coating material 12 on one side thereof in the same manner as described above. This electrode material 13 is joined to the center electrode 6 by a joining means such as resistance welding as shown in an application example 1 of FIG. Further, the voltage application direction to the electrode material 13 may be from the circumferential direction of the disk or from the axial direction of the upper or lower surface of the disk.

Incidentally, Ir or I as the substrate 11
Generally, when the alloy rich in r is processed into a plate shape, cracks and the like are generated and the workability is poor. Thereby, the surface defects of the base material 11 are covered, cracks are prevented from being generated, and workability is improved. Further, in the case of a Pt alloy formed on one side as shown in FIG. 1 (2), the surface in contact with the female mold side is formed as a Pt alloy-formed surface during press punching, so that the coating effect is improved. It is exhibited and cracks and the like do not occur.

In order to examine the characteristics of the electrode material 13 formed as described above, a width 50 mm and a length 50
mm, various materials of 0.8 mm in diameter and 0,0 mm in thickness.
A 5 mm electrode material was molded, a spark plug was manufactured, assembled into an internal combustion engine, operated for 100 hours, and its appearance and state of consumption were compared. For reference, the conventional material is Ir
And Pt electrode materials were also manufactured and tested at the same time.

Table 1 shows a list of electrode materials and test results of each sample. Here, the thickness ratio corresponds to the coating material 12.
The thickness of the substrate 11 is represented by a ratio, where the thickness of the substrate 11 is 1.

[0015]

[Table 1]

As shown in the test results, it is understood that the electrode material 13 of the present invention has no fatal chipping of the electrode material 13, has less wear, and has excellent ignition performance. According to the results of this test, a) the coating material 1 is applied to at least one of the front surface and the back surface of the base material 11;
As the Pt alloy of No. 2, one or more of Ir, Ni, and Rh are used in an amount of 0.5 to 30 wt. %
If the addition is less than 0.5%, the desired wear resistance cannot be obtained.
If the addition exceeds 30%, no improvement in workability as a coating effect is observed.

B) As the Ir alloy of the substrate 11, Pt,
One, two or more of Ni, Rh, and W are 0.1 to 2
5 wt. %, The addition of less than 0.1% does not provide the desired oxidation and volatility at high temperatures, and the addition of more than 25% results in a sharp decrease in workability and a decrease in arc resistance. Characteristics cannot be obtained. c) The ratio of the base material 11 and the Pt alloy as the coating material 12 formed on at least one of the front surface and the back surface is a thickness ratio,
When the Pt alloy is 1, the base material 11 is preferably set to 5 to 20. If the ratio of the base material 11 is less than 5, the expected arc resistance of the base material 11 cannot be obtained. Lumber 1
2, the protection against the workability and the covering effect become insufficient,
Cracks and the like are likely to occur, and the wear resistance is deteriorated, so that the desired characteristics cannot be satisfied. I understood that.

Accordingly, it can be understood that the above range is a range sufficient to obtain desired characteristics. Further, as another application example, as in application example 2 shown in FIG. 3, it may be used in a type in which discharge occurs between the electrode material 13 bonded to the center electrode 6 and the side electrode 5. As in application example 3 shown in FIG. 4, the electrode material 13 may be joined to both the center electrode 6 and the side electrode 5 and used as discharge units for each other.

[0019]

As described above, the present invention provides Ir,
Alternatively, an Ir alloy is used as a base material, and a Pt alloy is arranged on at least one of the front surface and the back surface, and a composite property is exhibited by a synergistic effect of these alloys. The effect of exhibiting characteristics excellent in wear resistance can be obtained.

Further, by forming a Pt alloy on at least one of the front surface and the back surface of the Ir or Ir alloy substrate, even if the substrate is relatively easy to crack, the surface defect of the substrate can be improved. To prevent the occurrence of cracks and improve the workability of the plate material. In addition, the surface in contact with the female mold side during press punching should be the surface on which the Pt alloy is formed. Thereby, an effect that a covering effect is exhibited and cracks and the like do not occur is obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is an application example 1 of the present invention.

FIG. 3 is an application example 2 of the present invention.

FIG. 4 is an application example 3 of the present invention.

FIG. 5 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Terminal part 2 Insulator 3 Mounting part 4 Screw part 5 Side electrode 6 Center electrode 11 Base material 12 Coating material

Claims (5)

[Claims] 1. A composite electrode material for ignition, characterized in that Ir is used as a base material and a Pt alloy is formed on at least one of its front and back surfaces. 2. A composite electrode material for ignition, comprising an Ir alloy as a base material and a Pt alloy formed on at least one of its front and back surfaces. 3. The method according to claim 2, wherein at least one of Pt, Ni, Rh, and W is 0.1 to 25 wt. %. A composite electrode material for ignition characterized by adding 0.1% by weight. 4. The Pt according to claim 1, 2 or 3, wherein Pt is formed on at least one of a front surface and a back surface of the base material.
As an alloy, at least one of Ir, Ni, and Rh is 0.5 to 30 wt. %. A composite electrode material for ignition characterized by adding 0.1% by weight. 5. The method according to claim 1, wherein the ratio of the thickness of the base material and the thickness of the Pt alloy formed on at least one of the front surface and the back surface is defined as the ratio of the Pt alloy. Let the thickness be 1,
A composite electrode material for ignition, wherein the thickness of the substrate is 5 to 20.