JP2000164318A - Spark plug for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spark plug for an internal combustion engine securing the easiness of machining when manufacturing and excellent in corrosion resistance. SOLUTION: At least one or more of a wire packing 12, a plate packing 14 and a gasket 16 and a main metal fitting 7 constituting a spark plug for an internal combustion engine are made of a Fe base alloy containing Cr 15% or above, then a passive state film is reliably formed on the surface without causing remarkable hardening of a material, and corrosion resistance can be sufficiently improved while the easiness of machining is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark plug used for an internal combustion engine, and more particularly to a wire packing, a plate packing, a gasket or a metal shell constituting the spark plug.

[0002]

2. Description of the Related Art In general, a metal shell constituting a spark plug used in an internal combustion engine, for example, a spark plug is conventionally subjected to a surface treatment such as zinc-plated colored chromate or nickel plating to suppress rust. However, it has been proposed to use a SUS material having high durability against salt water and acid.

[0003]

However, with the recent diversification of leisure activities, personal watercrafts and boats equipped with an internal combustion engine as a power source have become remarkably widespread. In this case, the spark plug used in the internal combustion engine is exposed to a salt water atmosphere, but the use of a SUS material that is resistant to salt water and acid in the metal shell constituting the spark plug reliably suppresses rust generation. However, problems such as sticking and breakage of the spark plug can be suppressed. On the other hand, wire packing which is sealed and placed together with a talc ring in a caulking portion with an insulator above a metal shell, and a gasket which is arranged around a body of a metal shell are generally provided with nickel or zinc plating for corrosion resistance. Has been improved. However, when the upper part of the metal shell is crimped in order to hold it on the insulator in the manufacturing process, the plating of the wire packing in the metal shell is peeled off by an external force at the time of crimping, and the Fe material base is easily exposed. When the base material comes into contact with the outside air and the salt water, red rust is generated, and problems such as sticking are likely to occur.

Further, since the plate packing sandwiched between the metal shell and the insulator leg is not generally subjected to a surface treatment such as plating, moisture generated from the metal shell tip due to combustion is generated. If it enters and aggregates at the position of the plate packing, it may easily rust. Further, the gasket disposed around the metal shell body is plated with nickel or zinc similarly to the wire packing described above to improve corrosion resistance. However, when the spark plug is screwed into the plug hole, there is a problem that the plating layer on the surface is easily peeled off by friction with the plug hole seating surface. That is, when the plating on the surface is peeled off, the Fe material base is exposed, and rust is easily generated by contact of the exposed Fe material base with salt water or the like.

Accordingly, the present invention is to solve the above-mentioned conventional problems. Spark plugs, especially wire packings arranged in the caulked portion of the metal shell, plate packings sandwiched by insulator legs in the metal shell, gaskets arranged around the shell of the metal shell, and further, the metal shell itself In order to prevent the generation of rust, the corrosion resistance is increased and the durability of the spark plug is sufficiently improved.

[0006]

For this purpose, an insulator having a center electrode held at the tip of the shaft hole and a terminal electrode at the rear end thereof, and an insulator held at the tip of the shaft hole of the insulator. A ground electrode is provided so as to face the tip of the center electrode. And in an internal combustion engine spark plug composed of a metal shell holding the insulator,
A packing is disposed in a gap formed between the metal shell and the insulator, a packing sandwiched between the insulator legs in the metal shell, and a gasket is disposed around the metal shell body. In addition, at least one of the packing and the gasket is made of F containing at least 15% of Cr.
It is made of an e-base alloy.

[0007] Further, the metallic shell constituting the above-mentioned spark plug for an internal combustion engine also has a F content containing 15% or more of Cr.
It is made of an e-base alloy.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A spark plug according to an embodiment of the present invention has a wire packing disposed in a gap formed between a metal shell and an insulator and an insulator leg in the metal shell. At least one of the plate packing sandwiched between the metal shells and the gasket disposed around the metal shell body is made of an Fe-based alloy containing 15% or more of Cr. This facilitates processing into the metal shell, and also forms a passivation film on the surface of the metal shell, thereby preventing rust and improving the durability of the spark plug itself. it can. That is, if the content of Cr is less than 15 wt%, the wire packing is disposed in a gap formed between the metal shell and the insulator, and is sandwiched between the insulator legs in the metal shell. The gasket that is placed around the plate packing and the metal shell body,
Since it does not harden significantly, molding by plastic working is easy. However, the formation of the passivation film on the surface of the wire packing, the plate packing and the gasket is incomplete, and a sufficient rust prevention effect cannot be exhibited. On the other hand, when the content of Cr is large, the formation of a passivation film mainly composed of Cr on the surface of the wire packing, the plate packing, and the gasket becomes sufficient. In this case, the Fe-based alloy, which is a material of the above, is remarkably hardened, and the forming by plastic working becomes extremely difficult. Therefore, if it is attempted to form the metal shell by cutting, the molding itself is possible, but the mass productivity is reduced and the production cost is significantly increased.

Further, the metal shell is made of an Fe-based alloy containing 15% or more of Cr, similarly to the wire packing, the plate packing and the gasket.
The generation of rust in the plate packing and the gasket is reliably suppressed by the passive film containing Cr as a main component. Thus, the corrosion resistance of the spark plug itself can be significantly improved, and the durability can be sufficiently improved.

[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. This spark plug (1) has a terminal electrode (4) at a rear end of a shaft hole (3) and a center at a front end. Insulator (2) that protrudes and holds electrode (5)
Equipped. Also, the center electrode (5) holding the insulator (2) and protruding from the tip of the insulator (2) and holding the center electrode (5)
A metal shell (7) is formed by integrally disposing the ground electrode (8) at a position facing the tip of the metal shell.

In the spark plug (1) for an internal combustion engine according to the embodiment of the present invention, the metallic shell (7)
In order to hold the insulator (2), a crimping portion (9) is provided which is crimped by pressing with a large external force. A wire packing (12) is sealed and arranged together with a talc ring (11) in a gap (10) formed between the metal shell (7) and the insulator (2). In addition, and in the metal shell (7), it is sandwiched between the inner diameter step (13) formed so as to protrude inward in the metal shell (7) and the insulator leg (6). A gasket (16) is arranged around the plate packing (14) and further around the metal shell body (15). These wire packing (12) and plate packing (14)
And at least one of the gaskets (16)
(For example, SUS304 material) containing 15% or more of Fe.

Since the spark plug (1) for an internal combustion engine according to the embodiment of the present invention has the above structure, the raw material itself does not harden remarkably, so that the wire packing (12) constituting the spark plug (1) is formed. ), Plate packing (1
4) The processing into the gasket (16) can be facilitated. Furthermore, since a sufficient passivation film (17) containing Cr as a main component is formed on the surfaces of the wire packing (12), the plate packing (14), and the gasket (16), the rust caused by salt water or the like is increased. Can be prevented, and the durability of the spark plug (1) itself can be improved. That is, if the Cr content is less than 15 wt%, the wire packing (12) and the inner diameter step (13) which are sealed and arranged in the gap (10) and the insulator leg (6) are sandwiched. The gasket (16) disposed around the metal packing (14) and the metal shell (15) does not harden remarkably, so that it can be easily formed by plastic working. However, the passivation film (1) on the surface of wire packing (12), plate packing (14), gasket (16)
The formation of 7) is incomplete and cannot exhibit a sufficient rust prevention effect.

If the content of Cr is large, the wire packing (12), the plate packing (14), and the gasket (1)
6) The formation of the passivation film (17) on the surface is sufficient. On the other hand, wire packing (12) and plate packing (1)
4) The Fe-based alloy, which is the raw material of the gasket (16), is extremely hardened, and it is extremely difficult to form by plastic working. Therefore, if it is attempted to form the wire packing (12), the plate packing (14), and the gasket (16) by cutting, the forming itself becomes possible, but the mass productivity is reduced and the production cost is significantly increased. That is the thing.

Further, as another embodiment of the present invention, the metal shell (7) is also provided with the above-mentioned wire packing (1).
2) Similarly, at least one of the plate packing (14) and the gasket (16) contains F containing 15% or more of Cr.
It is made of an e-base alloy (for example, SUS304 material). Passive film obtained by this (17)
The corrosion resistance of the metal shell (7) constituting the spark plug (1) for an internal combustion engine according to the embodiment of the present invention is also increased, and the durability of the spark plug (1) as a whole is sufficiently high. Can be improved.

[0015]

As described above, since the present invention is constituted, a passivation film is formed on these surfaces while facilitating the processing, and the corrosion resistance for preventing the generation of rust is improved. Therefore, the spark plug itself has an excellent effect of significantly improving the durability of the spark plug itself.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a spark plug for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of a spark plug for an internal combustion engine according to an embodiment of the present invention.

DESCRIPTION OF SYMBOLS 1 Spark plug for internal combustion engine 2 Insulator 3 Shaft hole 4 Terminal electrode 5 Center electrode 6 Insulator leg 7 Metal shell 8 Ground electrode 9 Caulked portion 10 Air gap 11 talc ring 12 wire packing 13 inner diameter step 14 Sheet packing 15 Metal shell 16 Gasket 17 Passive coating

Claims (2)

[Claims] An insulator having a center electrode held at the tip of a shaft hole and a terminal electrode at a rear end thereof, and an insulator opposed to a tip of the center electrode held at a tip of the shaft hole of the insulator. And a main body disposed in a gap formed between the metal shell and the insulator in the spark plug having the ground electrode arranged as described above and including the metal shell holding the insulator. An internal combustion in which at least one of a packing sandwiched between insulator legs in a metal fitting and a gasket arranged around a metal shell body is made of an Fe-based alloy containing 15% or more of Cr. Spark plug for engine. 2. The spark plug for an internal combustion engine according to claim 1, wherein the metal shell forming the spark plug for the internal combustion engine together with the insulator is also made of an Fe-based alloy containing 15% or more of Cr.