WO2011065596A1

WO2011065596A1 - Spark plug and method for welding spark plug electrode tip for manufacturing same

Info

Publication number: WO2011065596A1
Application number: PCT/KR2009/006954
Authority: WO
Inventors: 김현중; 신병헌; 조춘식; 송석기
Original assignee: 주식회사 유라테크
Priority date: 2009-11-25
Filing date: 2009-11-25
Publication date: 2011-06-03

Abstract

The present invention provides a spark plug and a method for welding a spark plug electrode tip for manufacturing the same. The spark plug comprises: a central electrode; an insulator which is combined to cover the central electrode; a metallic member which is combined to cover the insulator; a grounding electrode which is configured so that one end is combined with the metallic member and the other end faces the central electrode; and an electrode tip which is fixed to at least one of the mutually facing surfaces of the grounding electrode and the central electrode. The electrode tip is formed in a pipe shape. The method for welding the spark plug electrode tip comprises: the step of preparing the pipe-shaped electrode tip which has a hollow, and an electrode which is equipped with a fusion zone protruded to be inserted into the hollow; the step of assembly in which the fusion zone is inserted into the hollow of the electrode tip; and the first step of welding the electrode tip and the electrode by irradiating beams on the fusion zone through the hollow. Thus, the invention saves costs by reducing the quantity of high-priced precious metals required in the formation of electrode tips, and increases the explosion efficiency inside the engine. Further, the invention is capable of increasing weldability.

Description

Spark plug and spark plug electrode tip welding method for manufacturing the same

The present invention relates to an ignition plug for an internal combustion engine, and more particularly, to a spark plug having an electrode tip and a welding method between the electrode tip and the electrode.

In general, a spark plug is a device mounted on a cylinder head of an internal combustion engine to ignite an electric flame on a gas mixture of fuel and air supplied into a combustion chamber.

The spark plug is provided with a housing mounted to the cylinder head of the engine, disposed inside the housing through a center and wrapped in an insulator, protruding from the end of the housing, and one end of which is connected to the ignition coil so that a high voltage current is provided. It is composed of a center electrode is guided, and a ground electrode fixed to one side of the housing and disposed with a predetermined gap with the center electrode.

The center electrode and the ground electrode are generally composed of a copper compound having excellent thermal conductivity or nickel of high purity.

The insulator is wrapped around the outer circumferential surface of the center electrode in order to prevent high voltage from being discharged to portions other than generating sparks, and is formed of a ceramic material having excellent heat resistance insulation and the like.

In order to maintain durability and heat resistance and wear resistance while maintaining high ignition continuously under high pressure and high temperature environment, a center electrode tip formed of expensive precious metal is fused by welding, and the ground electrode The ground electrode tip, which is formed of an expensive precious metal, is also welded to the end of the electrode.

1 to 3 are process flowcharts illustrating a method for mounting an electrode tip to an electrode according to the prior art.

Looking at the method for mounting the electrode tip to the electrode according to the prior art, first, as shown in Figure 1, put the electrode tip 120 of the ball shape on the surface of the electrode 110 and the first spot (spot) welding Conduct. Then, the contact surface of the electrode tip 120 and the electrode 110 of the ball shape is fused while the junction of the electrode tip 120 and the electrode 110 is fused.

In this state, as shown in FIG. 2, the pressing portion 130 having a flat plate shape is pressed down on the upper surface of the electrode tip 120. Then, the upper surface of the electrode tip 120 is molded into a flat shape.

As shown in FIG. 3, secondary spot welding is performed to fix the gap between the electrode tip 120 and the electrode 110. In secondary welding, laser welding has recently been used.

However, when the electrode tip is mounted by the electrode tip mounting method according to the prior art as described above, as shown in the cross-sectional view of FIG. 4 and the cross-sectional photograph of FIG. There is a problem that the lifting portion 140 is generated. When the edge of the electrode tip is not fused, the phenomenon that the electrode tip is separated from the electrode during use occurs, the spark generation performance is deteriorated.

In addition, a humping phenomenon occurs in which bubbles are generated at the welded site due to the insufficient amount of molten melted by welding.

Further, since the melting point of the noble metal tip is much higher than the melting point of the material used as the electrode, the electrode portion is oxidized during welding, which causes the humping phenomenon.

In addition, expensive precious metals are excessively used, causing cost increase.

The present invention has been made to solve the above problems, it is possible to suppress the generation of pores in the weld, to improve the weldability, and to provide a spark plug electrode tip welding method for manufacturing the spark plug that can reduce the cost. For that purpose.

The present invention to solve the above problems, the center electrode; An insulator coupled to surround the center electrode; A metal fitting coupled to surround the insulator; A ground electrode having one end coupled to the bracket and provided with the other end facing the center electrode; And an electrode tip fixed to at least one of the center electrode and the ground electrode facing each other, wherein the electrode tip has a pipe shape.

Here, the electrode tip is formed of a precious metal material.

On the other hand, the present invention provides a spark plug electrode tip welding method as another field. The spark plug electrode tip welding method includes the steps of: providing a pipe-shaped electrode tip having a hollow formed therein and an electrode having a molten portion protruding from the hollow; An assembly step of fitting the hollow of the electrode tip to the melting part; And a first welding step of welding the electrode tip and the electrode by irradiating a beam to the melting part through the hollow.

Here, after the first welding step, the second welding step of performing a beam welding along the outer circumferential surface of the electrode tip and the electrode; preferably further comprises a.

In addition, the first welding step is effective to weld using a laser beam.

The second welding step is preferably welded using a laser beam.

Here, it is effective that the molten portion has a cone shape.

According to the problem solving means of the present invention as described above it can be expected a variety of effects including the following matters. However, the present invention is not achieved by exerting all of the following effects.

As described above, according to the embodiment of the present invention, the melted portion is formed in the electrode can accurately position the electrode tip in the center of the electrode.

In addition, since the melt portion is formed in a horn shape, there is an advantage that the electrode tip can be more easily assembled to the melt portion.

In addition, since the electrode tip is formed in a pipe shape having a hollow, it is possible to reduce the amount of precious metals, to increase the explosion efficiency inside the engine, and to reduce the surface contact area with the electrode, thereby reducing the generation of pores in the welded part. It can be further suppressed.

Further, by melting the melted portion and primary welding the electrode tip and the electrode, not only weldability is better, but also the amount of melting of the precious metal is reduced, so that a small precious metal can be used, thereby further reducing the cost.

In addition, since the primary welding portion and the secondary welding portion do not overlap each other, weldability can be further increased.

1 to 3 is a process flowchart showing a method for mounting an electrode tip on an electrode according to the prior art

4 and 5 are cross-sectional and cross-sectional photograph of the electrode tip and electrode welded according to the prior art

6 is a partially broken cross-sectional view showing one end of the spark plug manufactured using the electrode tip welding method of the embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view of a portion of the center electrode and the ground electrode of FIG. 6; FIG.

8 to 12 are views showing step by step the electrode tip welding method of the embodiment of the present invention

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

However, in describing the present invention, a detailed description of known functions or configurations will be omitted in order not to disturb the gist of the present invention.

As shown in FIG. 6, the spark plug includes a center electrode 3, an insulator 2 disposed outside the center electrode 3 and coupled to surround the center electrode 3, and an outside of the insulator 2. It includes a bracket (1) disposed in and coupled to surround the insulator (2), one end is coupled to the bracket (1), the other end is provided with a ground electrode (4) facing the center electrode (3). The

electrode tips

31 and 32 are fixed to at least one of the positions where the center electrode 3 and the ground electrode 4 face each other. The

electrode tips

31 and 32 are formed of a precious metal material. The noble metal refers to a metal chemically much larger than ionization energy of hydrogen and is not oxidized by an acid and an oxidizing agent, and includes gold, platinum, ruthenium, rhodium, osmium and iridium. The precious metal electrode tip 31 may be used with various kinds of precious metals such as iridium (Ir) and platinum (Pt).

7 is an enlarged cross-sectional view of a portion of the center electrode and the ground electrode of FIG. 6.

As shown in Fig. 7, the main body 3a of the center electrode 3 is tapered at its end, and its end face is formed flat. The electrode tip 31 is formed in the shape of a hollow pipe and is disposed on a flat end surface, and laser beam bonding, electron beam bonding or other suitable bonding technique is applied to the outer surface of the joint surface to form the junction line W. Thus, the electrode tip 31 is firmly fixed to the end surface of the center electrode (3).

Depending on the situation, one of the two

opposing electrode tips

31 and 32 may be omitted. In such a case, a spark discharge gap is formed between one of the

electrode tips

31, 32 and the ground electrode 4 (or the center electrode 3).

Naturally, the electrode tip 31 may be formed in various shapes such as a circular pipe and a square pipe.

As described above, the electrode tip 31 is formed in the shape of a pipe in which the hollow is formed, thereby forming a plurality of edges e1, e2, e3, and e4. In general, since sparks are more likely to occur at edges than planes, a large number of edges may generate a large number of sparks at the same time, thereby increasing explosion or combustion efficiency in the engine.

8 to 12 are views sequentially showing the spark plug noble metal electrode tip welding method of the present invention.

The spark plug electrode tip welding method according to an embodiment of the present invention includes an electrode having a pipe-shaped electrode tip 31 having a hollow 311 formed therein and a melting part 33 protruding from the hollow 311. 3) and the assembling step (FIG. 10) of fitting the hollow 311 of the electrode tip 31 to the melting part 33, and the hollow 311 It includes a first welding step (FIG. 11) for welding the electrode tip and the electrode by irradiating the beam 81 to the melting portion 33 through.

The electrode tip 31 may be formed in a pipe shape, and may be formed in a pipe shape having various shapes such as a circle, a rectangle, and a triangle. However, due to the ease of manufacture, the circle is most preferred. The precious metal electrode tip 31 is formed around 0.7mm in diameter, and the hollow 311 is preferably formed in 0.3mm or less. The hollow 311 of 0.3 mm or less may be formed by electric discharge machining or laser machining. By forming the electrode tip 31 in a pipe shape, the area in surface contact with the electrode 3 is reduced. This reduces the likelihood of porosity in the weld zone. In addition, since the total volume of the electrode tip 31 is reduced, the amount of expensive precious metal can be reduced, thereby reducing the cost.

As described above, the melting part 33 is formed to a size into which the hollow 311 may be fitted. The melting part 33 may be formed in various shapes such as a pillar or a horn body. However, when formed as a cone (cone) can be assembled much easier when assembling the electrode tip (31). Cones may be formed in various shapes such as cones, triangular pyramids, and the like. As described above, since the melting part 33 is provided, the electrode tip 31 can be accurately assembled to the electrode 3.

In the first welding step (FIG. 11), the beam 81 is melted through the hollow 311 to melt the melting part 33, thereby joining the electrode tip 31 and the electrode 3. The beam 81 may be a laser beam or the like. As such, since the melting part 33 is melted to weld the electrode tip 31 and the electrode 3, the weldability is good.

After the first welding step (FIG. 11), it is preferable to further include a second welding step (FIG. 12) for beam welding along the outer circumferential surface where the electrode tip 31 and the electrode 3 meet. That is, as shown in FIG. 12, the beam 82 is welded along the outer circumferential line of the electrode tip 31 and the electrode 3. As the beam welding, laser beam welding or the like may be used. Therefore, the electrode tip 31 and the electrode 3 can be more firmly combined. Moreover, in the case of laser welding after the conventional resistance welding, laser welding is repeatedly performed on the resistance welded portion, so that humping may occur due to oxidation or the like. 2, there is a difference in the welded area in the welding step, it is possible to prevent duplicate welding. Therefore, there is an effect that the weldability is much increased.

Although the preferred embodiments of the present invention have been described above by way of example, the scope of the present invention is not limited to these specific embodiments, and may be appropriately changed within the scope described in the claims.

Claims

Center electrode;

An insulator coupled to surround the center electrode;

A metal fitting coupled to surround the insulator;

A ground electrode having one end coupled to the bracket and provided with the other end facing the center electrode; And

An electrode tip fixed to at least one of the surfaces of the center electrode and the ground electrode facing each other;

Including,

The electrode tip is spark plug, characterized in that formed in the shape of a pipe.
The method of claim 1,

The electrode tip is a spark plug, characterized in that formed of a precious metal material.
In the spark plug electrode tip welding method,

Providing an electrode having a pipe-shaped electrode tip having a hollow formed therein and a molten portion protruding from the hollow;

An assembly step of fitting the hollow of the electrode tip to the melting part; And

A first welding step of welding the electrode tip and the electrode by irradiating a beam to the melting part through the hollow;

Spark plug electrode tip welding method comprising a.
The method of claim 3, wherein

After the first welding step,

A second welding step of performing beam welding along an outer circumferential surface of the electrode tip and the electrode;

Spark plug electrode tip welding method characterized in that it further comprises.
The method according to claim 3 or 4,

The first welding step is a spark plug electrode tip welding method, characterized in that for welding using a laser beam.
The method of claim 4, wherein

The second welding step is a spark plug electrode tip welding method, characterized in that for welding using a laser beam.
The method according to claim 3 or 4,

The melting portion of the spark plug electrode tip welding method characterized in that the conical shape.
In the spark plug electrode that is coupled to the hollow electrode-shaped electrode tip,

A melting part protruding to be inserted into the hollow at a surface coupled with the electrode tip of the electrode;

Spark plug electrode comprising a.
The method of claim 8,

The spark plug electrode, characterized in that the melt portion is formed in the shape of a cone.