JP3492453B2 - Spark plug electrode and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark plug electrode in which a noble metal is laser-welded to an ignition part.

[0002]

2. Description of the Related Art A recess is provided in the ignition part of an electrode base material, a precious metal material such as platinum is installed in the recess, and a laser beam is irradiated to melt the precious metal material and the electrode base material to solidify the precious metal material. Spark plugs have been manufactured using layered electrodes with precious metals.

[0003]

The inventor of the present invention has found that in the solidified noble metal layer, when the alloy component, for example, the Ni component of the electrode base material has a variation exceeding ± 15% by weight of the average value,
It was found that the spark wear resistance was low. An object of the present invention is to reduce variations in alloy components of a noble metal layer formed by melting and solidification, and to reduce the concentration to within ± 15% by weight of the average value of the components, and to improve the spark wear resistance of the spark plug. The purpose is to provide the manufacturing method.

[0004]

According to the present invention, a recess is provided on the surface of an ignition part of an electrode, a noble metal material is installed in the recess, and a laser beam is irradiated to the noble metal material and the electrode base material. It was melted, in the electrode of the spark plug to form a solidified precious metal layer between the noble metal member and the electrode base material, D the diameter or width of the surface of the solidified precious metal layer which requires the diameter or width of the noble metal member When B and thickness are A, 1 ≧ B / D ≧ 0.5 and A / B ≦ 0.6
Set so that the variation of alloy components in the solidified precious metal layer is uniform.
It is characterized in that the average value is within ± 15% by weight .

According to a second aspect of the present invention, there is provided a spark plug center electrode manufacturing method, in which a groove is provided around an outer peripheral surface of a center electrode which is an ignition part, a noble metal material is wound around the groove, and a laser beam is irradiated. , said base material of the noble metal member and the center electrode is melted in a center electrode spark plug manufacturing method for forming the solidified precious metal layer between the center electrode base material and the noble metal material, the width of the surface of the solidified precious metal layer to form Is D, the width of the precious metal material is B, and the thickness is A, 1 ≧ B /
When D ≧ 0.5 and A / B ≦ 0.6, the solidification
Variation of alloy composition of precious metal layer is ± 15% by weight of average value
It is characterized by being within .

According to a third aspect of the present invention, there is provided a spark plug electrode manufacturing method, wherein a recess is provided on a surface of an electrode base material of a center electrode or a ground electrode, which is an ignition part, and a precious metal material is installed in the recess, and a laser is produced. by irradiating a beam, the noble metal material and to melt the electrode base material, the electrode manufacturing method of the spark plug to form a solidified precious metal layer and the electrode base metal and the noble metal material, the surface of the solidified precious metal layer to form Where D is the diameter of the noble metal material, B is the diameter of the precious metal material, and A is the thickness of the precious metal material, 1 ≧ B / D ≧ 0.5 and A / B ≦ 0.6 are set . Average variation in alloy composition
Of less than ± 15% by weight .

[0007]

According to the present invention, along the entire surface of the solidified noble metal layer which is melted and solidified to have a predetermined width or diameter, the alloy component of the noble metal material and the electrode base material is aimed at ± 15 of the average value of the constituents. It can be kept within the weight%, and the spark wear resistance of the spark plug can be improved. In the present invention, the diameter of the solidified noble metal layer or noble metal material refers to an effective value converted into a circle in the case of a shape other than a circle, such as a polygon, an ellipse, or an ellipse.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a manufacturing process of a center electrode of a spark plug. As shown in (a) and (c) of FIG. 1, a groove 11 as a recess is provided around the outer periphery of the center electrode 1 serving as an ignition part, and a noble metal material 2 in the form of a strip is wound around the groove 11. . Next, while rotating the center electrode 1 around the axis, a laser beam R is irradiated with a width slightly wider than the groove width around the surface of the noble metal material 2 to form a base material for the noble metal material 2 and the center electrode 1. To melt. When this is cooled, (b) in FIG.
As shown in (d), the solidified noble metal layer 3 of the noble metal having the required width D and the center electrode base material is formed.

In the solidified noble metal layer 3, the spark wear resistance of the center electrode becomes low if there is a portion where the variation in alloy composition exceeds ± 15% by weight of the average value. Platinum P as precious metal material
t, when nickel Ni is used as the electrode base material, the solidified noble metal layer 3 has a target alloy component average value of Pt-20.
If Ni (Ni 20 wt%) is used, for example, Pt-40
When the Ni portion is partially generated, the spark consumption of this portion becomes large, which deteriorates the performance of the spark plug.

In the present invention, the alloy component of the solidified noble metal layer 3 is aimed to have a variation as a whole ± 15% by weight of the component average value.
When the width of the surface of the solidified noble metal layer 3 is D, the width of the noble metal material 2 is B, and the thickness is A so that
≧ B / D ≧ 0.5 and A / B ≦ 0.6 are set.

FIG. 2 shows data obtained by dividing the cross section near the surface of the solidified noble metal layer 3 shown in FIG. 1D into upper and lower parts into 13 equal parts and measuring the degree of dispersion of alloy components at 12 sampling points. The graph (A) shows the deviation from the target component average value 20 wt% (Pt-20Ni) when A / B = 0.5 with B / D as a parameter.
It can be seen that the variation of alloy components is within ± 15% by weight of the average value, 1 ≧ B / D ≧ 0.5. In addition, B
If / D is larger than 1, the width B of the noble metal material 2 becomes larger than the width of laser irradiation, and the noble metal material 2 remains unmelted, which is not preferable for use.

Graph (B) shows the variation from the target component average value of 20% by weight when B / D = 0.75 with A / B as a parameter. The variation of alloy components is within ± 15% by weight of the average value because A / B ≦ 0.
It turns out that it is 6. This is because when A / B> 0.6, the noble metal material is too thick and unmelted remains.

FIG. 3 shows various cross-sectional shapes of the strip-shaped noble metal material 2 wound around the groove 11. The cross-sectional shape may be one quadrangular cross section 41, a plurality of quadrangular cross sections 42, an elliptical or elliptical cross section 43, a coil cross section 44, a plurality of circular cross sections 45, an overlapping circular cross section 46, and the like. In these cases, an effective value or an effective value is used as the width B and the thickness A of the precious metal material 2.

FIG. 4 shows another embodiment. In this embodiment, a recess 5 is provided in the tip end surface 12 of the center electrode 1 which serves as an ignition part, a noble metal tip 6 is installed in the recess 5, and a solidified noble metal layer 7 is formed by laser beam welding. The recess 5
As shown in FIG. 5, the solidified noble metal layer 7 is provided on the outer peripheral surface of the center electrode 1 serving as the ignition part and on the side surface or the tip surface of the ground electrode 8.
1, 72, 73 may be formed.

Also in these cases, the solidified noble metal layer 7
Where D is the diameter of the surface, B is the diameter of the noble metal tip 6, and A is the thickness, 1 ≧ B / D ≧ 0.5 and A / B ≦ 0.
By setting to 6, the same effect can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view and a cross-sectional view of a center electrode tip portion of a spark plug.

FIG. 2 is a graph showing data on a mixing ratio of a molten / solidified noble metal layer.

FIG. 3 is a perspective view and a cross-sectional view of a center electrode tip portion of another embodiment.

FIG. 4 is a perspective view and a cross-sectional view of an electrode ignition part of another embodiment.

FIG. 5 is a perspective view of a tip portion of a spark plug using an electrode of another embodiment.

[Explanation of symbols]

1 Center electrode (firing part) 11 groove (recess) 2 precious metal materials 3 Solidified precious metal layer 8 installed electrodes

Continuation of front page (56) Reference JP-A-7-73954 (JP, A) JP-A-7-73956 (JP, A) JP-A-7-272826 (JP, A) JP-A-5-234662 (JP , A) JP-A-6-96837 (JP, A) JP-A-4-61780 (JP, A) JP-A-7-106050 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) H01T 13/00-21/00

Claims (3)

(57) [Claims] 1. A recess is provided on the surface of the ignition part of the electrode, a noble metal material is installed in the recess, and a laser beam is irradiated to melt the noble metal material and the electrode base material to form the noble metal material. in the electrode of the spark plug to form a solidified precious metal layer and the electrode base material, D the surface of the diameter or width of the solidified precious metal layer which requires, B the diameter or width of the noble metal material, the thickness is a Sometimes, 1 ≧ B / D ≧ 0.5 and A / B ≦ 0.6 are set, and the variation of alloy components of the solidified noble metal layer is ± 1 of the average value.
Spark plug electrode characterized by being within 5% by weight . 2. A groove is provided around the outer peripheral surface of the center electrode to be the ignition part, a noble metal material is wound around the groove, and a laser beam is irradiated to melt the noble metal material and the base material of the center electrode. in the center electrode spark plug manufacturing method for forming the solidified precious metal layer between the noble metal member and the center electrode base material, D the width of the surface of the solidified precious metal layer to form the width of the noble metal member B, thickness Where A is 1 ≧ B / D ≧ 0.
5, and set to A / B ≦ 0.6, ± variations in the alloy components of the coagulation noble metal layer is an average value of 1
A method of manufacturing a center electrode for a spark plug, characterized in that the content is within 5% by weight . 3. The noble metal material and the electrode are provided by providing a recess on the surface of the electrode base material of the center electrode or the ground electrode, which is the ignition part, and installing a noble metal material in the recess and irradiating a laser beam. the base material is melted, the electrode manufacturing method of the spark plug to form a solidified precious metal layer and the electrode base metal and the noble metal member, the diameter of the surface of the solidified precious metal layer to form D, and the diameter of the noble metal member B , And the thickness is A, 1 ≧ B / D ≧
0.5, and set to A / B ≦ 0.6, ± 1 variations in the alloy components of the coagulation noble metal layer is an average value
A method for producing an electrode of a spark plug, characterized in that the content is within 5% by weight .