JP2020165520A - Gasket for ignition plug, manufacturing method of ignition plug, and ignition plug - Google Patents

Abstract

To provide a gasket for an ignition plug which enables improvement of airtightness between a combustion chamber of an internal combustion engine and the outside.SOLUTION: A gasket for an ignition plug is used to attach an ignition plug to a wall part in a cylinder head of an internal combustion engine. The gasket for the ignition plug includes: an annular body part 23; protruding parts 25 protruding from the body part to the radial inner side; and first extension parts 41A which extend from the protruding parts to the side of a specific surface 22 that is a wall part side surface of the body part in an axial direction of the body part. Each first extension part separates from the body part except a connection part connected to the protruding part.SELECTED DRAWING: Figure 9

Description

The present invention relates to a gasket used for a spark plug, a method for manufacturing the spark plug, and an ignition plug.

Conventionally, a spark plug including a center electrode and a ground electrode is known (see Patent Document 1). The spark plug is attached to the internal combustion engine so that the air-fuel mixture in the combustion chamber of the internal combustion engine can be ignited by generating a discharge spark in the spark discharge gap between the center electrode and the ground electrode. The spark plug is provided with a mounting portion having a thread formed on the outer circumference, and when the spark plug is mounted on the internal combustion engine, the mounting portion is provided in the screw hole provided in the wall portion forming the combustion chamber of the internal combustion engine. Screw the threads. As a result, the center electrode and the ground electrode are inserted into the combustion chamber of the internal combustion engine.

In order to ensure airtightness between the internal combustion engine and the spark plug, a gasket may be interposed between the wall portion around the screw hole of the internal combustion engine and the seat portion of the spark plug. As a configuration of this gasket, for example, in Patent Document 1, a plurality of convex portions protruding inward in the radial direction are formed on the inner peripheral edge portion of the gasket. In gaskets, the distance from the point closest to the central axis of the gasket to the central axis of the gasket at the convex part is twice as small as the nominal diameter of the thread of the spark plug, so that the gasket has a mounting part and a seat. The gasket is prevented from falling off from the intermediate portion of the spark plug provided between the portions to the tip side (mounting portion side) in the axial direction.

Japanese Patent No. 6260040

The convex portion of the gasket is formed by applying a load to the inner peripheral edge portion of the gasket. When a load is applied to the inner peripheral edge of the gasket, strain or indentation is generated on the gasket, and waviness is formed. When the gasket is wavy, the area of the portion where the gasket comes into contact with the internal combustion engine or the spark plug varies, and the airtightness between the internal combustion engine and the spark plug decreases.

In the spark plug disclosed in Patent Document 1, in order to prevent the wavy portion of the gasket from coming into contact with the airtight surface of the seat portion of the spark plug, the thickness of the inner peripheral edge portion of the gasket is set to the diameter of the gasket. It is smaller toward the inside of the direction. However, if the thickness of the inner peripheral edge of the gasket is reduced, strain is generated in the entire gasket when a load is applied to the inner peripheral edge of the gasket, and the airtightness between the combustion chamber of the internal combustion engine and the outside is lowered. There is a risk.

The present invention has been made to solve the above problems, and a main object thereof is to provide a gasket for a spark plug capable of improving the airtightness between the combustion chamber of an internal combustion engine and the outside. is there.

The present invention is a spark plug gasket used when attaching a spark plug to a wall portion of a cylinder head of an internal combustion engine, and has an annular main body portion and a plurality of convex portions protruding inward in the radial direction from the main body portion. And a plurality of first extension portions extending from each of the convex portions to the side of a specific surface which is a surface of the main body portion on the wall portion side in the axial direction of the main body portion, and the first extension portion is provided. , Except for the connecting portion with the convex portion, it is separated from the main body portion.

When attaching a spark plug to a wall portion of a cylinder head of an internal combustion engine, a spark plug gasket (hereinafter, simply a gasket) is used for the purpose of ensuring airtightness between the combustion chamber and the spark plug. The gasket is formed with an annular main body portion, a plurality of convex portions protruding inward in the radial direction from the main body portion, and a plurality of first extension portions provided on each convex portion.

Each first extension extends from the corresponding convex portion toward a specific surface in the axial direction of the main body. Here, when a load is applied to the gasket to incline the first extension portion so as to be separated from the main body portion in order to prevent the gasket from coming off, the first extension portion is separated from the main body portion as the load is applied. It transforms like this. In this case, if the first extension portion is connected to the main body portion even in the portion other than the connection portion with the convex portion, the portion connected to the inclined portion of the main body portion due to the deformation of the first extension portion Deform. As a result, undulations are formed in the main body, and the airtightness between the combustion chamber of the internal combustion engine and the outside is reduced.

As a countermeasure, in the above configuration, the first extension portion is separated from the main body portion except for the connection portion with the convex portion. Therefore, the deformation of the main body when the first extension is tilted is suppressed. As a result, the waviness formed in the main body can be reduced, and the airtightness between the combustion chamber and the outside can be improved.

Further, the present invention is a gasket used when attaching a spark plug to a wall portion of a cylinder head of an internal combustion engine, and includes an annular main body portion and a plurality of convex portions protruding inward in the radial direction from the main body portion. A plurality of inclined portions extending from each of the convex portions and inclined toward a specific surface, which is a surface of the main body portion on the wall portion side, so as to be separated from the main body portion. , Except for the connecting portion with the convex portion, it is separated from the main body portion.

In the above configuration, the inclined portion is separated from the main body portion except for the connecting portion with the convex portion. Therefore, deformation of the main body portion when forming the inclined portion is suppressed. As a result, the waviness formed in the main body can be reduced, and the airtightness between the combustion chamber of the internal combustion engine and the outside can be improved.

Further, the present invention is a method for manufacturing a spark plug which is attached to a wall portion of a cylinder head of an internal combustion engine via a gasket, and has an annular main body portion and a plurality of protrusions protruding inward in the radial direction from the main body portion. After the forming step of forming the reference member including the portion, the insertion step of inserting the spark plug into the inner hole of the main body portion, and the insertion step, in each of the protruding portions, the wall portion side of the main body portion. A tilting step of separating the end portion on the specific surface side, which is the surface of the main body, from the main body along the circumferential direction of the main body, and inclining the end portion toward the specific surface so as to be separated from the main body. Be prepared.

According to the above configuration, in the reference member before the end portion of the projecting portion on the specific surface side is separated from the main body portion, the distance between the axial center of the reference member and the projecting portion is not reduced. Therefore, the spark plug can be inserted into the inner hole of the main body before the end portion is separated, and the reference member can be assembled to the spark plug.

Then, after assembling the reference member to the spark plug, this end portion is separated from the main body portion and inclined so as to be separated from the main body portion to form a gasket. Since the inner diameter of the formed gasket is reduced, it is possible to prevent the gasket from falling off from the spark plug.

Further, the protruding portion is formed so as to project inward in the radial direction from the main body portion, and the protruding portion is connected to the main body portion only in the radial direction. Therefore, when separating the end portion of the protruding portion on the specific surface side from the main body portion, by separating this end portion from the main body portion along the circumferential direction, the separated end portion is separated from the protruding portion. It is separated from the main body except for the part that is connected to the part that is not connected. As a result, when the separated end portion is tilted so as to be separated from the main body portion, deformation of the main body portion is suppressed. As a result, the waviness formed in the main body can be reduced, and the airtightness between the combustion chamber of the internal combustion engine and the outside can be improved.

Further, the present invention is a method for manufacturing a spark plug that is attached to a wall portion of a cylinder head of an internal combustion engine via a gasket, in which a metal plate material is punched out to form an annular frame portion and the radial direction of the frame portion. A press process for forming a plate-like member having a plurality of claws protruding inward, and the frame portion is bent inward in the radial direction of the frame portion from the outer periphery, and the plate material is overlapped in the surface direction of the frame portion. As a result, an annular main body portion is formed, and the plurality of claw portions are arranged so as to project inward in the radial direction from a part of the main body portion in the surface direction to form a reference member. A bending step of bending each of the claws to a specific surface side which is a surface of the main body on the wall side, and an insertion step of inserting the spark plug into the inner hole of the main body after the bending step. After the insertion step, after the bending step, each of the claw portions is inclined toward the specific surface so as to be separated from the main body portion.

According to the above configuration, a plate-shaped member for manufacturing a gasket can be formed by punching a metal plate material. Therefore, workability in the manufacture of the gasket can be improved.

Further, the inner diameter of the reference member whose claw portion is bent toward a specific surface is enlarged. Therefore, the spark plug can be inserted into the inner hole of the main body after the claw portion is bent, and the reference member can be assembled to the spark plug.

Then, after assembling the reference member to the spark plug, the claw portion is inclined toward a specific surface so as to be separated from the main body portion to form a gasket. Since the inner diameter of the formed gasket is reduced, it is possible to prevent the gasket from falling off from the spark plug.

Further, in the reference member in which the claw portion is bent toward the specific surface side, the claw portion is separated from the main body portion except for the portion connected to the main body portion. Therefore, when the claw portion is subsequently tilted so as to be separated from the main body portion, the deformation of the main body portion is suppressed. As a result, the waviness formed in the main body can be reduced, and the airtightness between the combustion chamber of the internal combustion engine and the outside can be improved.

Semi-sectional view of the spark plug. An enlarged sectional view of A in FIG. The perspective view of the gasket seen from the 2nd contact surface. The perspective view of the gasket in 1st Embodiment. The schematic diagram which shows each diameter dimension of a housing and a gasket. The figure for demonstrating each process of the manufacturing method of the gasket in 1st Embodiment. The perspective view of the gasket in the 2nd Embodiment. The figure for demonstrating each process of the manufacturing method of the gasket in 2nd Embodiment. The schematic diagram which shows the example of changing the shape of the protrusion. The schematic diagram which shows the example of changing the shape of the protrusion. The schematic diagram which shows the example of changing the shape of a main body. The schematic diagram which shows the example of changing the shape of a main body.

Hereinafter, each embodiment embodied in the spark plug 10 as an ignition plug used in an internal combustion engine will be described with reference to the drawings.

(First Embodiment)
As shown in FIG. 1, the spark plug 10 includes a cylindrical housing 11 made of a metal material such as iron. In this embodiment, the housing 11 corresponds to the "main metal fitting".

Inside the housing 11, the lower end of the cylindrical insulating insulator 12 is coaxially inserted. The insulating insulator 12 is formed of an insulating material such as alumina. By crimping the upper end portion 11A of the housing 11 with respect to the insulating insulator 12, the housing 11 and the insulating insulator 12 are integrally coupled. Then, in the lower part of the insulating insulator 12, the center electrode 13 is inserted and held in the through hole 12A.

The center electrode 13 is formed in a columnar shape using a Ni alloy having excellent heat resistance as a base material. Specifically, the inner material (center material) of the center electrode 13 is made of copper, and the outer material (outer skin material) is made of a Ni (nickel) -based alloy. The tip portion 13A of the center electrode 13 is exposed from the lower end of the insulating insulator 12.

A ground electrode 14 that is integrally curved and extends from the lower end surface of the housing 11 is arranged at a position facing the tip end portion 13A of the center electrode 13. That is, the ground electrode 14 is connected to the housing 11 and is curved so that the tip portion 14A of the ground electrode 14 faces the tip surface of the center electrode 13. The ground electrode 14 is also formed of a Ni-based alloy.

A terminal portion 15 is electrically connected to the upper portion of the center electrode 13. An external circuit that applies a high voltage for generating sparks is connected to the terminal portion 15.

A screw portion 11B as a mounting portion is formed on the outer periphery of the lower portion of the housing 11. On the outer circumference of the screw portion 11B, a screw thread 16 for attaching the spark plug 10 is formed in a screw hole 33 provided in the wall portion 32 of the cylinder head 30 of the internal combustion engine. The spark plug 10 is attached to the wall portion 32 of the cylinder head 30 by screwing the screw thread 16 and the screw hole 33. With the spark plug 10 attached to the wall portion 32 of the cylinder head 30, the center electrode 13 and the ground electrode 14 of the spark plug 10 are exposed in the combustion chamber 31.

A seat portion 11C having a diameter larger than the diameter of the screw portion 11B is formed on the upper portion of the screw portion 11B of the housing 11. The seat portion 11C projects radially outward of the spark plug 10 from the screw portion 11B, and is formed so as to cover the screw hole 33 by attaching the screw portion 11B to the screw hole 33. Further, an intermediate portion 11D is formed between the screw portion 11B and the seat portion 11C of the housing 11.

FIG. 2 shows an enlarged cross-sectional view of the intermediate portion 11D. FIG. 2 is an enlarged cross-sectional view of the region shown in FIG. 1A.

The intermediate portion 11D is formed so that the diameter is equal to the valley diameter of the thread 16 of the thread portion 11B, and functions as a relief portion of the rolling die when the thread 16 is formed by using the rolling die. ..

The housing 11 is formed by cutting a metal pipe formed by cold casting. The plug seat surface 17, which is the surface of the seat portion 11C on the intermediate portion 11D side, is formed so as to be a tapered surface whose diameter is reduced toward the intermediate portion 11D. Therefore, when the housing 11 is formed by cutting, the cutting tool is moved inward in the radial direction with respect to the metal pipe rotating around the axis to form the plug seat surface 17, and then the cutting tool is moved to the outside in the radial direction. It is possible to prevent the plug seat surface 17 from being damaged by the cutting tool when it is moved to. The inclination angle of the plug seat surface 17 with respect to the axial direction is, for example, 3 °.

An annular gasket 20 as a spark plug gasket is provided on the outer periphery of the intermediate portion 11D. The gasket 20 is used for attachment to the cylinder head 30. Specifically, a wall seating surface 34 perpendicular to the axial direction of the spark plug 10 is formed on the outer surface of the wall portion 32 of the cylinder head 30. When the spark plug 10 is attached to the wall portion 32 of the cylinder head 30, the gasket 20 comes into contact with the wall seat surface 34 and the plug seat surface 17, and keeps the space between the cylinder head 30 and the spark plug 10 airtight. To do. The gasket 20 has a first contact surface 21 that comes into contact with the plug seat surface 17 and a second contact surface 22 that comes into contact with the wall seat surface 34. In this embodiment, the second contact surface 22 corresponds to the “specific surface”.

FIG. 3 shows a perspective view of the gasket 20 as seen from the second contact surface 22 of the gasket 20. The gasket 20 includes an annular main body 23. The main body 23 has a solid annular shape, and its cross-sectional shape is substantially rectangular (see FIG. 4). Further, the gasket 20 includes a plurality of convex portions 25 protruding inward in the radial direction from the main body portion 23.

FIG. 4 is a perspective view of the gasket 20 showing the cross-sectional shape of the convex portion 25. FIG. 4 shows the cross-sectional shape of the convex portion 25 in the IV-IV cross section of FIG. 3 perpendicular to the circumferential direction.

The convex portion 25 has an arc shape along the inner peripheral surface 24 of the main body portion 23, and its cross-sectional shape is substantially rectangular. The convex portion 25 is provided at an end portion of the main body portion 23 opposite to the second contact surface 22, and its thickness is half that of the main body portion 23.

Further, the gasket 20 includes a plurality of inclined portions 26 that extend from each convex portion 25 and incline toward the second contact surface 22 so as to be separated from the main body portion 23. The inclined portion 26 has a plate shape and is curved along the inner peripheral surface 24 of the main body portion 23. The inclined portion 26 is connected to the convex portion 25 at the end portion on the inner peripheral side of the surface 25A on the second contact surface 22 side of the corresponding convex portion 25. In the present embodiment, the end portion on the inner peripheral side of the surface 25A corresponds to the “connecting portion”.

As shown in FIG. 4, the inclined portion 26 is separated from the main body portion 23 except for the connecting portion with the convex portion 25. That is, the inclined portion 26 is separated from the main body portion 23 in an arbitrary cross section including the inclined portion 26 and perpendicular to the axial direction of the gasket 20. Further, in the portion of the gasket 20 in which the inclined portion 26 is formed, the inner diameter of the gasket 20 is reduced by the amount in which the inclined portion 26 is formed. Therefore, in the gasket 20, the gasket 20 is prevented from coming off by using the inclined portion 26.

FIG. 5 is a schematic view showing each diameter dimension of the housing 11 and the gasket 20. FIG. 6 shows a schematic view when the spark plug 10 is arranged so as to be turned upside down with respect to FIG. 1 and the central axis of the gasket 20 is arranged so as to coincide with the central axis of the housing 11. ..

In the housing 11, the nominal diameter of the thread 16 of the threaded portion 11B is LA. Further, the minimum inner diameter of the gasket 20 in the portion where the inclined portion 26 is not formed, that is, twice the distance from the point closest to the central axis of the gasket 20 in the convex portion 25 to the central axis is defined as LB. At this time, in the gasket 20, the distance LB is set so as to satisfy LB> LA. Therefore, the gasket 20 in which the inclined portion 26 is not formed can be inserted into the intermediate portion 11D from the threaded portion 11B side.

Further, of the gasket 20, the LC is defined as twice the distance from the point closest to the central axis of the gasket 20 to the central axis at the inclined portion 26. At this time, in the gasket 20, the distance LC is set so as to satisfy LA> LC. As a result, the inclined portion 26 can prevent the gasket 20 from falling off from the spark plug 10.

The gasket 20 can be manufactured by carrying out the first to third steps described below, whereby the spark plug 10 is manufactured. FIG. 6 is a diagram for explaining each step of the method for manufacturing the gasket 20.

As shown in FIG. 6A, in the first step, a plate material made of a copper alloy is press-processed to form a main body portion 23 and a plurality of protruding portions 41 protruding inward in the radial direction from the main body portion 23. This is a step of forming a gasket precursor (hereinafter referred to as a reference member) 40 to be provided. In this step, a reference member 40 having a plurality of protrusions 41 having a tooth-shaped spline shape and having a plurality of protrusions 41 whose axial thickness is substantially the same as the axial thickness of the main body 23 is formed. Tooth. In this embodiment, the first step corresponds to the "forming step".

The second step is a step of inserting the spark plug 10 into the inner hole 45 of the main body 23 of the reference member 40. The inner diameter of the protruding portion 41 of the reference member 40 is set to be substantially the same as the inner diameter of the convex portion 25. That is, when the LB is twice the distance from the point closest to the central axis of the reference member 40 to the central axis in the protruding portion 41, the protruding portion 41 so as to satisfy LB> LA in the reference member 40. Is formed (see FIG. 5). Therefore, the spark plug 10 can be inserted into the inner hole 45 of the main body 23 from the screw portion 11B side. In this embodiment, the second step corresponds to the "insertion step".

As a result, the reference member 40 is seated from the first contact surface 21 to the plug seat surface 17 of the seat portion 11C. The reference member 40 seated on the plug seat surface 17 is centered using a centering jig (not shown), and then the third step is performed. Here, centering means adjusting the position of the reference member 40 so that the central axis of the reference member 40 coincides with (approaches) the central axis of the spark plug 10.

As shown in FIG. 6B, in the third step, after the insertion, the reference member 40 is seated on the plug seat surface 17 (not shown), and the second contact surface 22 of each protrusion 41 is seated. This is a step of separating the side end portion (hereinafter, simply the end portion) 41A from the main body portion 23 along the circumferential direction of the main body portion 23. In the third step, the annular cutting jig 50 is lowered in the axial direction of the main body 23 from the second contact surface 22 side of the main body 23 with respect to the reference member 40, and the end 41A is separated from the main body 23. To do. The inner diameter of the cutting jig 50 is formed to be slightly larger than the nominal diameter LA of the thread 16. In this step, the cutting jig 50 is lowered along the nominal diameter LA of the screw thread 16 to lower the cutting jig 50 in the axial direction of the main body 23.

An annular cutting blade 51 is provided at the lower end of the cutting jig 50. The diameter of the cutting blade 51 is formed to be slightly smaller than the inner diameter of the main body 23. Therefore, when the cutting jig 50 is lowered in the axial direction of the main body 23 while the central axis of the cutting jig 50 is arranged so as to coincide with the central axis of the main body 23, the cutting blade 51 lowers the end 41A. Is cut along the circumferential direction and separated from the main body 23.

An inclined surface 52 is formed on the inner diameter side of the cutting blade 51 so as to increase the diameter toward the cutting edge of the cutting blade 51. Therefore, the end portion 41A cut from the main body portion 23 is inclined by the inclined surface 52 in a direction away from the main body portion 23 from the first contact surface 21 side toward the second contact surface 22. Therefore, in the third step, the end portion 41A of each protruding portion 41 on the second contact surface 22 side is separated from the main body portion 23 along the circumferential direction of the main body portion 23 and directed toward the second contact surface 22. It can be said that the process is tilted so as to be separated from the main body 23. In this embodiment, the third step corresponds to the "tilt step".

As described above, in the third step, the end portion 41A separated from the main body portion 23 is deformed so as to be separated from the main body portion 23. In this case, if the end portion 41A is also connected to the main body portion 23 in a portion other than the portion 41B on the first contact surface 21 side of the protruding portion 41 that is not separated from the main body portion 23, the end portion 41A Along with the deformation, the portion connected to the end 41A of the main body 23 is deformed. As a result, undulations are formed in the main body 23, and the airtightness between the cylinder head 30 and the spark plug 10 is reduced.

In the present embodiment, the end portion 41A is separated from the main body portion 23 along the circumferential direction of the main body portion 23 prior to (or at the same time as the deformation) the end portion 41A is deformed. Specifically, the end portion 41A of the protruding portion 41 that protrudes inward in the radial direction from the main body portion 23 and is connected to the main body portion 23 only in the radial direction is the main body portion along the circumferential direction orthogonal to the radial direction. It is disconnected from 23. Therefore, the cut end portion 41A is separated from the main body portion 23 except for the connecting portion with the portion 41B on the first contact surface 21 side. As a result, when the end portion 41A is deformed so as to be separated from the main body portion 23, the deformation of the main body portion 23 is suppressed. As a result, the waviness formed in the main body 23 can be reduced, and the airtightness between the cylinder head 30 and the spark plug 10 can be improved.

Further, the third step is carried out with the reference member 40 seated on the plug seat surface 17. Therefore, when the third step is performed, the load applied to the reference member 40 causes an indentation on the portion of the reference member 40 that comes into contact with the plug seat surface 17. In addition, strain is generated around the portion of the reference member 40 where the indentation is formed.

In the present embodiment, the deformation of the main body 23 is suppressed in the third step. That is, in the third step, the load used for deforming the main body 23 is removed from the load applied to the reference member 40, and the load applied to the reference member 40 is reduced. Therefore, in the third step, indentations and strains generated on the reference member 40 can be suppressed, and the airtightness between the cylinder head 30 and the spark plug 10 can be improved.

In the cutting jig 50, a stopper 53 is provided on the outer peripheral side of the cutting blade 51. In the third step, the cutting jig 50 causes the stopper 53 to come into contact with the second contact surface 22 of the main body 23. Stop the descent. An arc portion 54 is formed at the connection portion between the cutting blade 51 and the stopper 53, and when the stopper 53 abuts on the second contact surface 22 of the main body portion 23, the arc portion 54 and the end portion 41A Of the cut end portions with the main body portion 23, the cut end portion 42 on the main body portion 23 side is pressed. As a result, it is possible to suppress the occurrence of burrs at the cut end portion 42, and it is possible to suppress the decrease in airtightness between the cylinder head 30 and the spark plug 10. As a result of the arc portion 54 pressing the cut end portion 42, the arc portion 27 is formed on the main body portion 23 (see FIG. 4).

The gasket 20 is formed by carrying out the first to third steps. That is, of the protruding portions 41, the inclined portion 26 is formed by the end portion 41A on the second contact surface 22 side separated in the third step. Further, the convex portion 25 is formed by the portion 41B on the side of the first contact surface 21 that has not been separated. As shown in FIG. 5, in the gasket 20, the inclined portion 26 is formed so as to satisfy LA> LC. Therefore, by forming the inclined portion 26, it is possible to prevent the gasket 20 from falling off to the tip side (screw portion 11B side) in the axial direction.

The present embodiment described in detail above has the following advantages.

The inclined portion 26 is separated from the main body portion 23 except for the connecting portion with the convex portion 25. Therefore, the force applied to the main body 23 when forming the inclined portion 26 is suppressed, and the deformation of the main body 23 is suppressed. As a result, the waviness formed in the main body 23 can be reduced, and the airtightness between the cylinder head 30 and the spark plug 10 can be improved.

Specifically, in the third step, the end 41A on the second contact surface 22 side of the plurality of protrusions 41 provided on the reference member 40 is deformed so as to be separated from the main body 23, and the inclined portion 26 To form. In the present embodiment, prior to deforming the end portion 41A, the end portion 41A is separated from the main body portion 23 along the circumferential direction of the main body portion 23. Therefore, the separated end portion 41A is separated from the main body portion 23 except for the portion 41B on the first contact surface 21 side that was not separated from the main body portion 23, that is, the connection portion with the convex portion 25. .. Therefore, when the end portion 41A is deformed so as to be separated from the main body portion 23, the deformation of the main body portion 23 can be suppressed, and the airtightness between the cylinder head 30 and the spark plug 10 can be improved. ..

-In the third step, since the deformation of the main body 23 is suppressed, the load applied to the gasket 20 when forming the inclined portion 26 is reduced. Therefore, strain and indentation generated in the gasket 20 when the inclined portion 26 is formed can be suppressed, and the airtightness between the cylinder head 30 and the spark plug 10 can be improved.

In the third step, in the reference member 40 before the end portion 41A is separated from the main body portion 23, the distance between the central axis of the reference member 40 and the protruding portion 41 is not shortened. Specifically, in the reference member 40 before the end portion 41A is separated from the main body portion 23, the protruding portion 41 is formed so as to satisfy LB> LA (see FIGS. 5 and 6). Therefore, the spark plug 10 can be inserted from the screw portion 11B side into the inner hole 45 of the main body portion 23 in the reference member 40 before the end portion 41A is separated from the main body portion 23.

Further, in the third step, the inner diameter of the gasket 20 in which the end portion 41A is separated from the main body portion 23 and the inclined portion 26 is formed is reduced. Specifically, the inclined portion 26 is formed so as to satisfy LA> LC (see FIG. 5). Therefore, the inclined portion 26 can prevent the gasket 20 from falling off toward the tip end side in the axial direction.

In the third step, the end portion 41A is cut from the main body portion 23 by using the annular cutting blade 51. Therefore, by moving the cutting jig 50 provided with the cutting blade 51 from the second contact surface 22 side of the main body 23 along the axial direction of the main body 23, a plurality of inclined portions 26 can be formed at the same time. , Workability in the manufacture of the gasket 20 can be improved. Further, the annular cutting blade 51 has higher strength than the arc-shaped cutting blade for forming each inclined portion 26 in order. Therefore, damage to the cutting blade 51 can be suppressed, and an increase in the manufacturing cost of the gasket 20 can be suppressed.

-In the first step, the reference member 40 is formed by pressing a plate material made of a copper alloy. Therefore, workability in manufacturing the gasket 20 can be improved. Further, the formed reference member 40 is symmetrical on the front and back sides, and it is not necessary to judge the front and back sides. Therefore, after the first step, when the spark plug 10 is inserted into the inner hole 45 of the main body 23 of the reference member 40 in the second step, it is not necessary to determine the front and back of the reference member 40, and the workability at the time of insertion is improved. Can be made to.

In the gasket 20, the convex portion 25 is provided at an end portion of the main body portion 23 opposite to the second contact surface 22. Therefore, the inclined portion 26 provided on the second contact surface 22 side can be formed to be relatively large, and the gasket 20 can be appropriately suppressed from coming off by using the inclined portion 26.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment.

In the present embodiment, the cross-sectional shape of the main body 23 of the gasket 20 is different. In the present embodiment, as shown in FIG. 7, the plate material 60 having a plate thickness dimension TH is bent in the radial direction of the main body 23, and the main body 23 is formed by stacking the main body 23 in three layers in the axial direction. There is. The plate material 60 is a plate material made of a copper alloy, and its plate thickness dimension TH is 1/3 of the thickness of the main body 23 in the axial direction.

Further, in the present embodiment, the convex portion 25 and the inclined portion 26 are formed of the plate material 60 forming the main body portion 23. As shown in FIG. 7, the convex portion 25 and the inclined portion 26 are continuous with the inner peripheral side of the portion of the triple plate member 60 forming the main body portion 23 that is arranged on the first contact surface 21 side. It is provided.

The gasket 20 can be manufactured by carrying out the eleventh to fifteenth steps described below, whereby the spark plug 10 is manufactured. FIG. 8 is a diagram for explaining each step of the method for manufacturing the gasket 20 of the present embodiment.

As shown in FIG. 8A, the eleventh step is a step of forming the plate-shaped member 61 by pressing the plate member 60. The plate-shaped member 61 is provided with an annular frame portion 64 and a plurality of convex portions (hereinafter, claw portions) 62 protruding inward in the radial direction of the frame portion 64. In this embodiment, the eleventh step corresponds to the "pressing step".

As shown in FIG. 8B, in the twelfth step, among the plate-shaped members 61, the frame portion 64 is bent in a Z shape from the outer circumference to the inside in the radial direction of the frame portion 64, and the plate member 60 is bent into the plate-shaped member 61. This is a step of forming an annular main body portion 23 by overlapping in the plane direction of the above. By forming the main body portion 23, the plurality of claw portions 62 provided on the plate-shaped member 61 project inward in the radial direction from a part of the main body portion 23 in the axial direction (plane direction of the plate-shaped member 61). Arranged to do. Therefore, the twelfth step can be said to be a step of forming a gasket precursor (hereinafter, reference member) 63 including the main body portion 23 and a plurality of claw portions 62 protruding inward in the radial direction from the main body portion 23. In this embodiment, the twelfth step corresponds to the "forming step".

As shown in FIG. 8C, the thirteenth step is a step of bending each claw portion 62 toward the second contact surface 22 side of the main body portion 23. By bending the claw portion 62, the inner diameter of the reference member 63 is expanded. In this embodiment, the thirteenth step corresponds to the "bending step".

After the thirteenth step, the fourteenth step is carried out. The 14th step is a step of inserting the spark plug 10 into the inner hole 65 of the main body 23 of the reference member 63. As described above, the inner diameter of the reference member 63 after the thirteenth step is expanded. Therefore, the spark plug 10 can be inserted from the screw portion 11B side into the inner hole 65 of the main body portion 23 in the reference member 63 in which the claw portion 62 is bent in the direction in which the inner diameter increases. In this embodiment, the 14th step corresponds to the "insertion step".

As a result, the reference member 63 is seated on the plug seat surface 17 of the seat portion 11C. The reference member 63 seated on the plug seat surface 17 is centered using a centering jig (not shown), and then the fifteenth step is performed.

As shown in FIG. 8D, in the fifteenth step, after the insertion, each claw portion 62 is placed on the second contact surface 22 with the reference member 63 seated on the plug seat surface 17 (not shown). This is a step of inclining the main body portion 23 so as to be separated from the main body portion 23. In the fifteenth step, the annular bending jig 70 is lowered from the second contact surface 22 side of the main body 23 with respect to the reference member 63 in the axial direction of the main body 23, and the claw portion 62 is separated from the main body 23. Tilt to do. The inner diameter of the bending jig 70 is formed to be slightly larger than the nominal diameter LA of the screw thread 16. In this step, the bending jig 70 is lowered along the nominal diameter LA of the screw thread 16 to lower the bending jig 70 in the axial direction of the main body 23.

An annular pressing portion 71 is provided at the lower end of the bending jig 70. The diameter of the pressing portion 71 is formed to be slightly smaller than the inner diameter of the main body portion 23. Therefore, when the bending jig 70 is lowered in the axial direction of the main body 23 while the central axis of the bending jig 70 is arranged so as to coincide with the central axis of the main body 23, the pressing portion 71 causes the claw portion 62. The surface of the main body 23 side is pressed, and the claw portion 62 is deformed so as to be separated from the main body 23.

An inclined surface 72 is formed on the inner diameter side of the pressing portion 71 so as to increase the diameter toward the tip of the pressing portion 71. Therefore, the claw portion 62 is inclined toward the second contact surface 22 by the inclined surface 72 in a direction away from the main body portion 23. In this embodiment, the fifteenth step corresponds to the "tilt step".

As described above, in the fifteenth step, the claw portion 62 is deformed so as to be separated from the main body portion 23. The portion 62A of the claw portion 62 excluding the end portion 62B on the first contact surface 21 side connected to the main body portion 23 (hereinafter, the portion on the second contact surface 22 side) 62A is on the first contact surface 21 side. It is separated from the main body 23 except for the connection with the end 62B. As a result, when the claw portion 62 is deformed so as to be separated from the main body portion 23, the deformation of the main body portion 23 is suppressed. As a result, the waviness formed in the main body 23 can be reduced, and the airtightness between the cylinder head 30 and the spark plug 10 can be improved.

Further, in the fifteenth step, the deformation of the main body 23 is suppressed, so that the load applied to the reference member 63 in the fifteenth step is reduced. Therefore, in the fifteenth step, indentations and strains generated on the reference member 63 can be suppressed, and the airtightness between the cylinder head 30 and the spark plug 10 can be improved.

In the fifteenth step, the bending jig 70 stops descending when the pressing portion 71 comes into contact with the surface of the claw portion 62 on the main body portion 23 side. Therefore, it is not necessary to provide a stopper on the bending jig 70, and the bending jig 70 is formed in a thin tubular shape.

The gasket 20 is formed by carrying out the eleventh to fifteenth steps. That is, the inclined portion 26 is formed by the portion 62A on the second contact surface 22 side of each claw portion 62. Further, the convex portion 25 is formed by the end portion 62B on the first contact surface 21 side.

-According to the present embodiment described above, in the thirteenth step, the plurality of claws 62 bent toward the second contact surface 22 of the main body 23 are separated from the main body 23 in the fifteenth step. The inclined portion 26 is formed by being deformed into. Of the claws 62, the portion 62A on the second contact surface 22 side excluding the end 62B on the first contact surface 21 side connected to the main body 23 is separated from the main body 23. Therefore, when the claw portion 62 is deformed so as to be separated from the main body portion 23, the deformation of the main body portion 23 can be suppressed, and the airtightness between the cylinder head 30 and the spark plug 10 can be improved. ..

In the thirteenth step, the inner diameter of the reference member 63 in which the claw portion 62 is bent toward the second contact surface 22 of the main body portion 23 is expanded. Therefore, the spark plug 10 can be inserted from the screw portion 11B side into the inner hole 65 of the main body portion 23 of the reference member 63 in which the claw portion 62 is bent.

Further, in the fifteenth step, the inner diameter of the gasket 20 in which the claw portion 62 is deformed so as to be separated from the main body portion 23 and the inclined portion 26 is formed is reduced. Therefore, the inclined portion 26 can prevent the gasket 20 from falling off toward the tip end side in the axial direction.

In the fifteenth step, the claw portion 62 is moved so as to be separated from the main body portion 23 by using the annular bending jig 70. Therefore, by moving the bending jig 70 from the second contact surface 22 side of the main body 23 along the axial direction of the main body 23, a plurality of inclined portions 26 can be formed at the same time, and workability in manufacturing the gasket 20 can be formed. Can be improved. Further, the annular bending jig 70 is stronger than the arc-shaped bending jig for forming each inclined portion 26 in order. Therefore, damage to the bending jig 70 can be suppressed, and an increase in the manufacturing cost of the gasket 20 can be suppressed.

In the eleventh step, the plate-shaped member 61 is formed by pressing the plate material 60 made of a copper alloy. Therefore, workability in manufacturing the gasket 20 can be improved. Further, the formed plate-shaped member 61 is symmetrical on the front and back sides, and it is not necessary to judge the front and back sides. Therefore, after the 11th step, when the frame portion 64 of the plate-shaped member 61 is bent in the radial direction to form the reference member 63 in the 12th step, it is not necessary to determine the front and back of the plate-shaped member 61, and the work at the time of formation The sex can be improved.

It should be noted that the above embodiment can be modified and implemented as follows. The same parts as those in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

9 and 10 are schematic views showing an example of changing the shape of the protrusion 41 in the reference member 40 of the first embodiment. As shown in FIG. 9, a dividing groove 43 may be formed in advance between the end portion 41A of the protruding portion 41 on the second contact surface 22 side and the main body portion 23. When the dividing groove 43 is formed, it is not necessary to cut the end portion 41A from the main body portion 23 when forming the inclined portion 26. Therefore, the waviness formed in the main body 23 at the time of cutting can be suppressed, and the airtightness between the cylinder head 30 and the spark plug 10 can be improved.

In FIG. 9, the end portion 41A is connected to the end portion on the inner peripheral side of the surface 46 on the second contact surface 22 side of the portion 41B on the first contact surface 21 side. The end portion 41A extends from the portion 41B on the first contact surface 21 side toward the second contact surface 22 in the axial direction of the main body 23, and is connected to the portion 41B on the first contact surface 21 side. Except for the part, it is separated from the main body part 23. In FIG. 9, the end portion 41A corresponds to the “first extension portion”, and the portion 41B on the first contact surface 21 side corresponds to the “convex portion”.

Further, as shown in FIG. 10, the dividing groove 43 is provided not only between the end 41A on the second contact surface 22 side of the protrusion 41 and the main body 23, but also the first contact surface 21 of the protrusion 41. Of the side portion 41B (see FIG. 9), the protruding portion 41 may be formed between the end portion (hereinafter, simply the end portion) 41C on the first contact surface 21 side and the main body portion 23. In this case, the protruding portion 41 is connected to the main body portion 23 by the central portion 41D of the portion 41B on the first contact surface 21 side of the protruding portion 41 in which the dividing groove 43 is not formed.

In FIG. 10, the end portion 41A is connected from the central portion 41D to the end portion on the inner peripheral side of the surface 44A on the second contact surface 22 side in the axial direction of the main body portion 23. The end portion 41A extends from the central portion 41D toward the second contact surface 22 in the axial direction of the main body portion 23, and is separated from the main body portion 23 except for the connection portion with the central portion 41D.

Further, the end portion 41C is connected from the central portion 41D to the end portion on the inner peripheral side of the surface 44B on the first contact surface 21 side in the axial direction of the main body portion 23. The end portion 41C extends from the central portion 41D toward the first contact surface 21 in the axial direction of the main body portion 23, and is separated from the main body portion 23 except for the connection portion with the central portion 41D. In FIG. 10, the end portion 41C corresponds to the “second extension portion”.

In the reference member 40 shown in FIG. 10, when the inclined portion 26 is formed, one of the end portion 41A and the end portion 41C is deformed so as to be separated from the main body portion 23. Therefore, of the end portion 41A and the end portion 41C, the inclined portion 26 is formed by the deformed end portion. Further, the convex portion 25 is formed by the central portion 41D.

Further, the reference member 40 shown in FIG. 10 is symmetrical on the front and back sides, and it is not necessary to judge the front and back sides. Therefore, when the reference member 40 is inserted into the intermediate portion 11D, it is not necessary to determine the front and back of the reference member 40, and the workability at the time of insertion can be improved.

11 and 12 are schematic views showing an example of changing the shape of the main body 23 in the gasket 20 of the second embodiment. As shown in FIG. 11, the main body portion 23 may be formed by stacking the plate members 60 twice in the axial direction of the main body portion 23, or may be stacked four or more layers to form the main body portion 23. .. Further, the method of bending the plate material 60 is not limited to the Z shape, and as shown in FIG. 12, it may be bent in a spiral shape.

The number of inclined portions 26 formed on the gasket 20 is not limited to the number shown in the above embodiment, and may be two or more. Further, the angle width of the portion where each inclined portion 26 is formed is not limited to the angle width shown in the above embodiment.

For example, the angle width of the portion where each inclined portion 26 is formed may be made as large as possible, and the distance between two adjacent inclined portions 26 may be made as small as possible. As a result, it is possible to suppress the occurrence of strain between the portion where the inclined portion 26 is formed and the portion where the inclined portion 26 is not formed, and the airtightness between the cylinder head 30 and the spark plug 10 can be improved. Can be improved.

Further, for example, the angle width of the portion where each inclined portion 26 is formed may be made as small as possible, and the total value of the angle widths may be made as small as possible. As a result, the load applied to the reference member 40 when the inclined portion 26 is formed can be reduced. As a result, indentations and strains generated on the reference member 40 can be suppressed, and the airtightness between the cylinder head 30 and the spark plug 10 can be improved.

In the first embodiment, an example is shown in which the inner diameter of the main body 23 is constant and the diameter of the cutting blade 51 is slightly smaller than the inner diameter of the reference member 40. When the inner diameter of the main body 23 is not constant, the diameter of the cutting blade 51 may be formed to be slightly smaller than the minimum inner diameter of the main body 23. The same applies to the diameter of the pressing portion 71 in the bending jig 70 of the second embodiment.

-The gasket 20 does not necessarily have to be made of a copper alloy, and may be made of another type of metal.

-The plug seat surface 17 does not necessarily have to be a tapered surface, and may be a flat surface.

The main body 23 does not necessarily have to be a solid annular member, and may be a hollow annular member, for example, as shown in FIG.

The diameter of the intermediate portion 11D does not necessarily have to be equal to the valley diameter of the thread 16, and may be smaller than the nominal diameter LA of the thread 16. The diameter of the intermediate portion 11D is preferably equal to or less than the valley diameter of the thread 16, so that the intermediate portion 11D can be used as a relief portion for the rolling die.

10 ... Spark plug, 20 ... Gasket, 22 ... Second contact surface, 23 ... Main body, 25 ... Convex, 30 ... Cylinder head, 32 ... Wall, 41A ... End.

Claims (10)

A gasket (20) for a spark plug used when attaching a spark plug (10) to a wall portion (32) of a cylinder head (30) of an internal combustion engine.
The annular body (23) and
A plurality of convex portions (25) protruding inward in the radial direction from the main body portion,
A plurality of first extension portions (41A) extending from each convex portion toward a specific surface (22), which is a surface of the main body portion on the wall portion side in the axial direction of the main body portion, are provided.
The first extension portion is a spark plug gasket separated from the main body portion except for a connection portion with the convex portion. A gasket (20) for a spark plug used when attaching a spark plug (10) to a wall portion (32) of a cylinder head (30) of an internal combustion engine.
The annular body (23) and
A plurality of convex portions (25) protruding inward in the radial direction from the main body portion,
A plurality of inclined portions (26) extending from each of the convex portions and inclined toward a specific surface (22) which is a surface of the main body portion on the wall portion side so as to be separated from the main body portion are provided. ,
The inclined portion is a gasket for a spark plug that is separated from the main body portion except for a connecting portion with the convex portion. The spark plug gasket according to claim 1 or 2, wherein each of the convex portions is provided at an end portion of the main body portion opposite to the specific surface. A second extension portion (41C) extending from each of the convex portions to the side opposite to the specific surface in the axial direction of the main body portion is provided.
The spark plug gasket according to claim 1 or 2, wherein the second extension portion is separated from the main body portion except for a connection portion with the convex portion. A method for manufacturing an ignition plug (10), which is attached to a wall portion (32) of a cylinder head (30) of an internal combustion engine via an ignition plug gasket (20).
A forming step of forming a reference member (40) including an annular main body portion (23) and a plurality of protruding portions (41) protruding inward in the radial direction from the main body portion.
An insertion step of inserting the spark plug into the inner hole of the main body, and
After the insertion step, in each of the protruding portions, the end portion (41A) on the specific surface (22) side, which is the surface of the main body portion on the wall portion side, is inserted along the circumferential direction of the main body portion. A method for manufacturing a spark plug, comprising a tilting step of separating from the spark plug and tilting the spark plug toward the specific surface so as to be separated from the main body. In the tilting step, the cutting blade (51) having an annular shape and having a diameter smaller than the minimum inner diameter in the portion of the main body portion where the protruding portion is not provided is formed from the specific surface side of the main body. The method for manufacturing a spark plug according to claim 5, wherein the end portion is cut from the main body portion by moving the portion along the axial direction. The method for manufacturing a spark plug according to claim 5 or 6, wherein in the forming step, a metal plate material is punched out to form the reference member. A method for manufacturing an ignition plug (10), which is attached to a wall portion (32) of a cylinder head (30) of an internal combustion engine via an ignition plug gasket (20).
A plate material (60) made of metal is punched out to form a plate-shaped member (61) including an annular frame portion (64) and a plurality of claw portions (62) protruding inward in the radial direction of the frame portion. Press process and
The frame portion is bent inward in the radial direction of the frame portion from the outer circumference, and the plate members are overlapped in the surface direction of the frame portion to form an annular main body portion (23), and the plurality of claw portions are formed by the plurality of claw portions. A forming step of forming a reference member (63) by arranging the main body portion so as to project inward in the radial direction from a part of the surface direction.
A bending step of bending each of the claws toward a specific surface (22), which is a surface of the main body on the wall side.
After the bending step, an insertion step of inserting the spark plug into the inner hole of the main body portion and
A method for manufacturing a spark plug, comprising: after the insertion step, and after the bending step, an inclination step of inclining each of the claw portions toward the specific surface so as to be separated from the main body portion. In the tilting step, the bending jig (70) having an annular shape and having a diameter smaller than the minimum inner diameter in the portion of the main body portion where the claw portion is not provided is moved from the specific surface side to the main body. The method for manufacturing a spark plug according to claim 8, wherein the claw portion is tilted by moving the portion along the axial direction. The spark plug gasket (20) according to claim 2 and a tubular main metal fitting (11) are provided.
The main metal fitting is
A mounting portion (11B) having a screw thread (16) formed on the outer periphery for mounting in a screw hole (33) provided in the wall portion, and a mounting portion (11B).
A seat portion (11C) that protrudes radially outward from the mounting portion and covers the screw hole by mounting the mounting portion on the screw hole.
It has an intermediate portion (11D) provided between the mounting portion and the seat portion, the diameter of which is smaller than the nominal diameter of the thread.
The spark plug gasket is an ignition plug (10) provided on the outer periphery of the intermediate portion.
The nominal diameter of the thread is LA.
Of the spark plug gaskets, LB is twice the distance from the point closest to the central axis of the spark plug gasket at the convex portion to the central axis, and from the point closest to the central axis at the inclined portion. Let the LC be twice the distance to the central axis.
Spark plug with LB>LA> LC.

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