KR101386107B1 - Spark plug and welding method for electrode tip in spark plug for fabrication the same - Google Patents

Abstract

An ignition plug and an ignition plug electrode tip welding method for manufacturing the same are disclosed. The spark plug comprises a center electrode; An insulator coupled to surround the center electrode; A bracket coupled to surround the insulator; A ground electrode connected at one end to the metal member and having an opposite end facing the center electrode; And an electrode tip fixed to at least one of facing surfaces of the center electrode and the ground electrode. The electrode tip is formed in a pipe shape. A method of welding an ignition plug electrode tip, comprising: providing an electrode having a hollow shaped pipe-shaped electrode tip and a molten metal portion protruding to fit into the hollow; Assembling the hollow portion of the electrode tip into the melting portion; And a first welding step of irradiating a beam to the fused portion through the hollow to weld the electrode tip and the electrode. Therefore, it is possible not only to reduce the required amount of the electrode tip formed of the expensive precious metal, but also to increase the explosion efficiency inside the engine. Further, there is an advantage that the weldability can be increased.

spark plug

Description

FIELD OF THE INVENTION [0001] The present invention relates to an electrode tip welding method for spark plugs and an ignition plug for manufacturing the electrode spark plugs,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition plug for an internal combustion engine, and more particularly, to an ignition plug having an electrode tip and a welding method between the electrode tip and the electrode.

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

The ignition plug includes a housing mounted on a cylinder head of the engine, a housing disposed to pass through the center of the housing and being surrounded by an insulator, protruding from an end of the housing and having one end connected to the ignition coil, And a ground electrode fixed to one side of the housing and disposed with a certain gap from the center electrode.

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

The insulator is formed of a ceramic material that is wrapped around the outer circumferential surface of the center electrode to prevent the high voltage from being discharged to a portion other than the area where the spark is generated, and is excellent in heat resistance and insulation.

In order to maintain durability, heat resistance and abrasion resistance while maintaining high ignitability under a high-pressure and high-temperature environment, a center electrode tip formed of a noble metal, which is expensive, is welded to the end of the center electrode by welding, A ground electrode tip formed of a noble metal, which is expensive, is welded by welding.

FIGS. 1A to 1C are process flow diagrams illustrating a method for mounting an electrode tip on an electrode according to the prior art.

As shown in FIG. 1A, a ball-shaped electrode tip 120 is placed on a surface of an electrode 110, and spot welding is firstly applied to the electrode. Conduct. As a result, the contact surface between the electrode tip 120 and the electrode 110 is melted and the joint between the electrode tip 120 and the electrode 110 is fused.

In this state, as shown in FIG. 1B, the plate-shaped pressing portion 130 is lowered and pressed on the upper surface of the electrode tip 120. Then, the upper surface of the electrode tip 120 is shaped into a flat shape.

Then, as shown in FIG. 1C, secondary spot welding is performed to fix the electrode tip 120 and the electrode 110. Secondary welding has recently been used for laser welding.

However, when the electrode tip is attached by the electrode tip mounting method according to the related art as described above, both edges of the electrode tip 120 can not be fused together as shown in the sectional view of FIG. 2A and the sectional view of FIG. There is a problem that the exciting part 140 is generated. If the edge of the electrode tip can not be fused, the electrode tip is detached from the electrode during use, and the spark generation performance is deteriorated.

In addition, the amount of the molten metal to be melted by welding is insufficient to cause a hump phenomenon in which bubbles are generated at the welded portion.

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 site is oxidized during welding, which causes the hump phenomenon.

In addition, expensive noble metal is excessively used, which causes an increase in cost.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above problems, and it is an object of the present invention to provide an ignition plug capable of suppressing the occurrence of pores in a welded portion, improving weldability and reducing cost, and an electrode tip welding method of an ignition plug for manufacturing the same. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, An insulator coupled to surround the center electrode; A bracket coupled to surround the insulator; A ground electrode connected at one end to the metal member and having an opposite end facing the center electrode; And an electrode tip fixed to at least one of facing surfaces of the center electrode and the ground electrode, wherein the electrode tip is formed in a pipe shape.

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

On the other hand, the present invention provides, as another field, a spark plug electrode tip welding method. A method of welding an ignition plug electrode tip, comprising: providing an electrode having a hollow shaped pipe-shaped electrode tip and a molten metal portion protruding to fit into the hollow; Assembling the hollow portion of the electrode tip into the melting portion; And a first welding step of irradiating a beam to the fused portion through the hollow to weld the electrode tip and the electrode.

Here, it is preferable to further include a second welding step of performing, after the first welding step, a beam welding along an outer circumferential surface where the electrode tip meets the electrode.

Further, it is effective that the first welding step is performed using a laser beam.

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

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

As described above, according to the present invention, various effects including the following can be expected. However, the present invention does not necessarily achieve the following effects.

As described above, according to the embodiment of the present invention, the melted portion is formed on the electrode so that the electrode tip can be precisely positioned at the center of the electrode.

Further, since the molten portion is formed in the shape of a cone, the electrode tip can be easily assembled to the molten portion.

In addition, since the electrode tip is formed into a hollow pipe shape, the amount of noble metal can be reduced, the explosion efficiency can be increased inside the engine, and the surface contact area with the electrode is reduced, Can be further suppressed.

By melting the molten portion and first welding the electrode tip and the electrode, not only the weldability is better, but also the melting amount of the noble metal is reduced, so that the small noble metal can be used, and the cost can be further reduced.

Further, since the primary welding and the secondary welding portions do not overlap with each other, the weldability can be further increased.

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

In the following description of the present invention, a detailed description of known functions and configurations will be omitted so as not to obscure the gist of the present invention.

3 is a partially cutaway cross-sectional view showing one end of an ignition plug manufactured using an electrode tip welding method according to an embodiment of the present invention.

3, 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 a ground electrode 4 having one end coupled to the metal member 1 and the other end facing the center electrode 3. The ground electrode 4 is connected to the metal electrode 3, The electrode tips 31 and 32 are fixed to at least one of the facing positions of the center electrode 3 and the ground electrode 4. The electrode tips 31 and 32 are formed of a noble metal material. Precious metals refer to metals whose ionization energy is much higher than the ionization energy of hydrogen and which are not oxidized by acids and oxidizing agents, such as gold, platinum, ruthenium, rhodium, osmium and iridium. The noble metal electrode tip 31 may be formed of various kinds of precious metals such as iridium (Ir) and platinum (Pt)

Fig. 4 is a partially enlarged cross-sectional view of the center electrode and the ground electrode of Fig. 3;

As shown in Fig. 4, 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 face, and laser beam bonding, electron beam bonding or other suitable bonding technique is applied to the outer surface of the connecting face to form the bond line W , Whereby the electrode tip 31 is firmly fixed to the end face of the center electrode 3.

One of the two opposing electrode tips 31 and 32 may be omitted depending on the situation. In such a case, a spark discharge gap is formed between one of the electrode tips 31 and 32 and the ground electrode 4 (or the center electrode 3).

It is a matter of course that the electrode tip 31 may be formed in various shapes such as a circular pipe, a square pipe and the like.

As described above, the electrode tip 31 is formed into a pipe shape having a hollow, thereby forming a plurality of edges e1, e2, e3, and e4. Generally, since the spark is generated at the corner more than the plane, the large number of corners means that a large number of sparks are generated at the same time, so that the explosion or the combustion efficiency inside the engine can be increased.

5 to 9 sequentially illustrate the welding method of the electrode tip of the spark plug noble metal of the present invention.

An electrode tip welding method for an ignition plug according to an embodiment of the present invention includes an electrode tip 31 having a hollow 311 formed therein and an electrode 33 having a molten portion 33 protruding to be fitted into the hollow 311 (FIG. 7) in which the hollow 311 of the electrode tip 31 is inserted into the molten portion 33 (FIG. 7), and the hollow 311 And a first welding step (FIG. 8) in which the electrode tip and the electrode are welded by irradiating the welded portion 33 with a beam 81 through the first welding step.

The electrode tip 31 is formed in a pipe shape, and may be formed into a pipe shape of various shapes such as a circle, a square, and a triangle. However, the circle is most preferable due to the ease of manufacture. It is preferable that the noble metal electrode tip 31 has a diameter of about 0.7 mm and the hollow 311 has a diameter of about 0.3 mm or less. The hollow 311 of 0.3 mm or less can be formed by electric discharge machining or laser machining. By forming the electrode tip 31 in the shape of a pipe, the area of surface contact with the electrode 3 is reduced. This reduces the possibility of pores in the welds. In addition, since the total volume of the electrode tip 31 is reduced, the amount of expensive noble metal can be reduced, and the cost can be reduced.

The molten portion 33 is formed in such a size that the hollow 311 can be fitted, as described above. The fused portion 33 may be formed in various shapes such as a column or a cone. However, when the electrode tip 31 is formed of a cone, the electrode tip 31 can be easily assembled. The cone may be formed in various shapes such as a cone, a triangular pyramid, and the like. As described above, by providing the melting portion 33, there is an advantage that the electrode tip 31 can be accurately assembled to the electrode 3. [

The first welding step (FIG. 8) dissolves the fused portion 33 through the hollow 311 to join the electrode tip 31 and the electrode 3. The beam 81 may be a laser beam or the like. As described above, since the electrode tip 31 and the electrode 3 are welded by melting the molten portion 33, there is an advantage that the weldability is good.

It is preferable to further include a second welding step (FIG. 9) in which, after the first welding step (FIG. 8), the beam welding is performed along the outer circumferential surface where the electrode tip 31 and the electrode 3 meet. That is, as shown in FIG. 9, the beam 82 is welded along the outer circumferential line of the electrode tip 31 and the electrode 3. For beam welding, laser beam welding or the like may be used. Therefore, the electrode tip 31 and the electrode 3 can be joined more firmly. In addition, when laser welding is performed after resistance welding in the related art, laser welding is repeatedly performed on the resistance welded portion, which may cause hump due to oxidation or the like. In the case of the present invention, 2 There is a difference in the part to be welded in the welding step, so that overlapping welding can be prevented. Therefore, there is an effect that the weldability is much increased.

As described above, according to the embodiment of the present invention, the melted portion is formed on the electrode so that the electrode tip can be precisely positioned at the center of the electrode.

Further, since the molten portion is formed in the shape of a cone, the electrode tip can be easily assembled to the molten portion.

By melting the molten portion and first welding the electrode tip and the electrode, not only the weldability is better, but also the melting amount of the noble metal is reduced, so that the small noble metal can be used, and the cost can be further reduced.

Further, since the primary welding and the secondary welding portions do not overlap with each other, the weldability can be further increased.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

FIGS. 1A to 1C are flow charts illustrating a method of mounting an electrode tip on an electrode according to the prior art.

FIGS. 2A and 2B are cross-sectional and sectional views of electrode tips and electrodes welded in accordance with the prior art;

Fig. 3 is a partially cutaway cross-sectional view showing one end of an ignition plug manufactured using the electrode tip welding method of the embodiment of the present invention

Fig. 4 is a partially enlarged cross-sectional view of the center electrode and the ground electrode of Fig. 3

5 to 9 are views showing stepwise the electrode tip welding method of the embodiment of the present invention

DESCRIPTION OF REFERENCE NUMERALS

3: center electrode 2: insulator

1: metal fitting 4: grounding electrode

31, 32: electrode tip 33:

311: hollow

Claims (9)

A center electrode; An insulator coupled to surround the center electrode; A bracket coupled to surround the insulator; A ground electrode connected at one end to the metal member and having an opposite end facing the center electrode; And An electrode tip fixed to at least one of opposing surfaces of the center electrode and the ground electrode; / RTI > Wherein the electrode tip is formed in a pipe shape formed of a noble metal material. delete In an ignition plug electrode tip welding method, An electrode having a hollow-shaped pipe-shaped electrode tip and a molten portion protruding to be fitted into the hollow; Assembling the hollow portion of the electrode tip into the melting portion; And A first welding step of irradiating a beam to the fused portion through the hollow to weld the electrode tip and the electrode; Wherein the spark plug electrode tip welding method comprises the steps of: The method of claim 3, After the first welding step, A second welding step of performing beam welding along an outer circumferential surface where the electrode tip meets the electrode; Further comprising the step of welding the electrode tip of the spark plug. The method according to claim 3 or 4, Wherein the first welding step is performed using a laser beam. 5. The method of claim 4, Wherein the second welding step is performed using a laser beam. The method according to claim 3 or 4, Wherein the molten portion has a cone shape. delete delete

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