JP3277263B2 - Method of manufacturing spark plug for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a spark plug for an internal combustion engine, and more particularly to a method of manufacturing a multi-polar spark plug in which a plurality of spark gaps are formed between a side surface of a center electrode and a ground electrode. .

[0002]

2. Description of the Related Art Conventionally, in a spark plug for an internal combustion engine, a parallel electrode that forms a spark gap between a center electrode tip and a ground electrode has been generally used.
In recent years, in particular, due to demands for countermeasures against breakage of the ground electrode and reduction of the discharge voltage difference between the positive and negative polar electrodes, a plurality of spark gaps have been created between the side face of the tip of the center electrode and the end face of the ground electrode. The number of formed multi-polar spark plugs is increasing.

[0003]

However, in the case of the above-mentioned conventional multipolar spark plug in which a plurality of spark gaps are formed between the side face of the tip of the center electrode and the end face of the ground electrode, Since the side surface of the center electrode forming the portion and the end surface of the ground electrode are both formed with curved surfaces, it is difficult to adjust the spark gap, and the curved surface of the end surface of the ground electrode is subjected to preliminary bending of the ground electrode. Since it is necessary to perform punch forming again, it is difficult to secure the precision in forming the ground electrode, and it is necessary to adjust the spark gap again, which is troublesome, and furthermore, only the end face of the ground electrode is a flat surface. In this case, the spark discharge at the center electrode occurs only at the end of the ground electrode and the nearest part, and the durability of the center electrode and the ground electrode against spark wear may not be sufficient. That.

[0004] Therefore, a flat side surface portion is provided on the side surface of the tip of the center electrode, and when the center electrode having the flat side surface portion is assembled with the insulator joined in the shaft hole and the metal shell, Since the positional relationship with the end surface of the ground electrode to be welded to the front end surface of the metal shell needs to be matched, when assembling the insulator to which the center electrode is fixed and the metal shell, the alignment accuracy is ensured. There is a disadvantage that it is difficult to do.

The present invention has been made in order to solve the above-mentioned drawbacks of the prior art, and has an advantage in that the durability and countermeasures against breakage can be advantageously achieved by a simple method. To produce a multipolar spark plug which forms a spark gap with the end face of the spark plug.

[0006] A spark gap is formed between the side face on the tip end side in the axial direction of the center electrode and the end faces of the plurality of ground electrodes, and the side face of the center electrode forming the spark gap and the end face of the ground electrode are flat. In the method for manufacturing a spark plug for an internal combustion engine that is a surface, the side electrode is joined to an insulator with the center electrode having a flat surface, and the insulator is
When the L-shaped ground electrode made of a nickel alloy is previously welded to the metal shell which has been welded to the front end surface of the metal shell, an assembling jig is used to align the end surface of the ground electrode with the side surface of the center electrode. A centering jig adapted to the shape of the front end side of the center electrode is arranged and assembled on the side where the front end side of the center electrode of the tool is to be turned. Further, the insulator to which the center electrode is joined is
In assembling the L-shaped ground electrode made of a nickel alloy to the welded metal shell, a side portion of the center electrode and the ground electrode are processed by image processing from a direction in which a tip side of the center electrode of the mounting jig is turned. Of the center electrode and the end surface of the ground electrode, and then assembling them.

Further, a noble metal tip is bonded to at least one of the flat side surface of the center electrode and the flat end surface of the ground electrode.

[0008]

With the above configuration, the side surface of the tip of the center electrode forming the spark gap and the end surface of the ground electrode are flat, so that the spark gap can be easily adjusted and the spark abrasion can be reduced. Since it is minimized, the durability can be improved.

Further, a spark gap is formed between the side face on the tip end side in the axial direction of the center electrode and the end faces of the plurality of ground electrodes, and the side face of the center electrode forming the spark gap and the end face of the ground electrode are formed. When manufacturing a spark plug for an internal combustion engine having a flat surface, when assembling an insulator to which a center electrode having a flat front surface is bonded and a metal shell formed by previously bonding a ground electrode to the front surface. Then, from the side where the front end side of the center electrode of the assembly jig is to be directed, insert a centering jig adapted to the shape of the front end side of the center electrode onto the front end side of the center electrode, and then apply the metal shell. By crimping and assembling on the insulator, the assembling operation can be performed efficiently while adjusting the spark gap. Then, in the assembling work of the metallic shell formed by joining the insulator that is joined to the center electrode and the ground electrode,
By using the image processing, it is possible to accurately position the flat side surface of the center electrode and the end surface of the ground electrode. In addition, by joining the noble metal tip to the flat side surface of the center electrode or the end surface of the ground electrode, it is possible to improve the durability of the spark plug for an internal combustion engine after manufacturing.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. (1) is a spark plug for an internal combustion engine according to an embodiment of the present invention. As shown in FIGS. 1 and 2, the spark plug (1) for an internal combustion engine has a center at a tip end of a shaft hole (3). The electrode (4) holds a terminal electrode (5) at its rear end, and encloses a resistor (7) sandwiched by conductive glass seals (6) (6) in the shaft hole (3). A plurality of ground electrodes (10) are joined to the insulator (2) at the tip end surface (9), and a threaded portion (threaded below) is screwed into a plug hole when mounted on the internal combustion engine. 11).

Then, a plurality of spark gaps (1) are formed on the side surfaces (12) and (12) of the center electrode (4) on the tip side and the end surfaces (13) and (13) of the ground electrode (10).
4), (14), and the spark gap (14),
(14) a side surface part (12) of the center electrode (4),
(12) and end faces (13), (13) of the ground electrode (10)
Are flat surfaces. In order to further improve the durability of the spark plug (1) for an internal combustion engine, the center electrode (4) forming the spark gaps (14), (14)
Noble metal tip (18) on side (12), (12) of
(18) and / or the end face (1) of the ground electrode (10).
Noble metal chips (19) and (19) are joined to 3) and (13).

In addition, as shown in FIGS. 4 and 5, a center electrode (4) having a flat side surface (12) on the side surface of the tip is joined to an insulator (2). When assembling (2) to the metal shell (8) which is made of a nickel alloy or the like and is welded to the metal shell (8) on the front end surface (9) of the metal shell (8) in advance, the ground electrode (10) ) Is aligned with the flat side surface (12) of the center electrode (4) so that the tip end of the center electrode (4) of the mounting jig (15) is oriented toward After the centering jig (17) conforming to the shape of the front end side of the center electrode (4) is arranged, the caulking jig (16) is pressurized and the annular rear edge (20) of the metal shell (8) is pressed. ) Is pressed inward and assembled. In addition, when the insulator (2) to which the center electrode (4) is joined is attached to an L-shaped metal shell (8) to which a ground electrode (10) made of a nickel alloy or the like is welded, an assembling jig is used. The side surface (12) that becomes the flat surface of the center electrode (4) and the flat surface of the ground electrode (10) by the image processing (21) from the side where the tip side of the center electrode (4) of the tool (15) is to be turned. The positional relationship with the end face (13) is determined, the positions of both sides are corrected, and the metal shell (8) is similarly crimped and assembled.

Since the present invention has the above configuration, the side surface (1) of the center electrode (4) forming the spark gap (14) is formed.
Since the end surface (13) of the ground electrode (2) and the end surface (13) of the ground electrode (10) are flat with each other, it is easy to adjust the spark gap, and the side surface (12) of the center electrode (4) generated by spark discharge. In addition, spark wear of the end face (13) of the ground electrode (10) can be minimized, and the side face (12) of the center electrode (4) or the end face (13) of the ground electrode (10) can be formed. By joining a noble metal tip (18) with little spark consumption to at least one of the noble metal tips (19), the durability of the spark plug (1) for an internal combustion engine against spark consumption can also be improved.

A spark gap is formed between the side surfaces (12) and (12) of the center electrode (4) and the end surfaces (13) and (13) of the ground electrodes (10) and (10). (1
4), (14), and the spark gap (1)
4) Central electrodes (12) and (12) forming (14)
And ground electrodes (10), end faces (13) of (10), (1)
In manufacturing a so-called multi-polar type spark plug (1) for an internal combustion engine having a flat surface 3), an insulator (2) to which a center electrode (4) is joined and a nickel alloy or the like are previously formed. When the ground electrodes (10) and (10) are assembled with the metal shell (8) to be joined to the distal end surface (9), the side on which the distal end side of the center electrode (4) of the assembling jig (15) faces. A centering jig (17) adapted to the shape of the front end of the center electrode (4) is inserted into the front end of the center electrode (4), and the side surface (1) of the center electrode (4) is inserted.
2), (12) and the ground electrodes (10), after positioning the end faces (13) and (13) of the (10), and assembling the center electrode (4) accurately. The work of assembling the insulator (2) and the metal shell (8) to which the ground electrodes (10) and (10) are joined can be performed efficiently, and the thickness of the centering jig (17) is reduced by the internal combustion. It is possible to simplify the manufacturing process of the multi-pole type internal combustion engine spark plug (1) of the present invention, which corresponds to the plug gap in the finished product of the engine spark plug (1) (FIG. 3, (See FIG. 4).

Then, in the work of assembling the insulator (2) to which the center electrode (4) is joined and the metal shell (8) to which the ground electrode (10) is joined, images from a computer, an image from a camera, etc. By utilizing the processing (21), the positional relationship between the side surface (12), which is the flat surface of the center electrode (4), and the end surface (13) of the ground electrode (10) is determined by insulating the center electrode (4). By rotating and correcting the body (2), the side surface (12) that becomes the flat surface of the center electrode (4) and the end surface (1) of the ground electrode (10) are accurately and quickly.
3) can be performed (FIG. 5 (a),
(B)).

The side surface (12) of the center electrode (4)
FIG. 6 shows that the end face (13) of the ground electrode (10) corresponding to the side face (12) of the center electrode (4) should form a spark gap (14) as a flat face. As shown, the tip of the center electrode (4) has a triangular prism shape, and the ground electrode (1) corresponds to each side (12 ').
0) may be disposed.

Therefore, the side face (12) of the center electrode (4) and the end face (13) of the ground electrode (10) are flat as in the embodiment of the present invention, and the side face of the conventional center electrode (4). A plurality of spark gaps are formed between the ground electrode and the end face of the ground electrode, and only the end face of the multi-electrode spark plug (conventional example A) and the end face of the ground electrode in which the side face of the center electrode and the end face of the ground electrode have curved surfaces mutually When a durability test was performed with a multipolar spark plug (conventional example) having a flat surface, the rate of increase of the spark gap portion (14) with respect to time was greater in the embodiment of the present invention than in the conventional example. Thus, the effect of improving durability against spark consumption caused by spark discharge was recognized (FIG. 7).

[0018]

As described above, by forming a so-called multi-pole type spark plug for an internal combustion engine in which the side surface at the tip of the center electrode and the corresponding end surface of the ground electrode are flat surfaces, the spark accompanying the spark discharge can be obtained. Since the wear can be minimized, the durability of the spark plug itself can be improved, and in manufacturing the spark plug for an internal combustion engine, the centering jig is attached to the tip of the center electrode from below the assembly jig. By performing an assembling operation after inserting into the part, and further performing image processing by a computer in this assembling operation, there is an excellent effect that accuracy and speed in the spark plug manufacturing process can be improved. Things.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a tip portion of a spark plug according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating an operation of assembling an insulator and a metal shell in a spark plug manufacturing process.

FIG. 4 is an enlarged perspective view of the main part.

FIGS. 5A and 5B are diagrams showing an assembling operation using image processing, wherein FIG. 5A is an enlarged sectional view of the assembling operation, and FIG.

FIG. 6 is an enlarged perspective view of a spark plug according to another embodiment of the present invention.

FIG. 7 is a diagram showing the results of a durability test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spark plug for internal combustion engines 2 Insulator 3 Shaft hole 4 Center electrode 5 Terminal electrode 6 Conductive glass seal 7 Resistor 8 Metal shell 9 Tip surface 10 Ground electrode 11 Screw part 12 (Center electrode) Side part 13 (Ground electrode) ) End surface 14 Spark gap 15 Assembly jig 16 Caulking jig for assembly 17 Centering jig 18, 19 Noble metal tip 20 Rear edge 21 Image processing

Claims (3)

(57) [Claims] 1. A side portion and a plurality of side portions on a tip side in a central electrode axial direction.
Of to form the spark gap to the end surface of the ground electrode, the manufacturing method of the spark plug for an internal combustion engine in which the end surface of the side portion and the ground electrode of the center electrode forming the spark gap is a flat surface, the center electrode the side surface portion is a flat surface with bonding the insulator, the insulator, in advance metallic shell consists of nickel alloy on the distal end surface L-shaped and the said ground electrode is welded to main when assembled to bracket the alignment of the side surface portion of the end surface and the center electrode of the contact <br/> ground electrode is directed tip side of the center electrode of the assembling jig
A method for manufacturing a spark plug for an internal combustion engine, wherein a centering jig adapted to the shape of the front end side of the center electrode is disposed on the side to be assembled and assembled. The method according to claim 2 wherein the said center electrode are joined insulator, when assembled to the metal shell in which the ground electrode is welded, the tip of the center electrode of the assembling jig
Image processing from the side where the side will be turned up
Indexing the positional relationship <br/> between the end surface of the side portion and the ground electrode of the serial center electrode, an end surface of the side portion and the ground electrode of said center electrode
2. The method for manufacturing a spark plug for an internal combustion engine according to claim 1, wherein the position of the spark plug is corrected and then assembled. 3. The method for manufacturing a spark plug for an internal combustion engine according to claim 1, wherein a noble metal tip is joined to at least one of a side surface portion of the center electrode and an end surface of the ground electrode.