JP2855773B2 - gasket - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a gasket used for a cylinder head gasket, an exhaust manifold gasket and the like of an automobile engine.

2. Description of the Related Art Conventionally, as this type of gasket, there is known a gasket in which a plate-shaped gasket body is provided with a through-hole serving as a high-pressure portion to be sealed, and a shim ring surrounding the through-hole is provided in the gasket body. (Japanese Utility Model Laid-Open No. 59-188955).

[Problems to be Solved by the Invention] By the way, when the shim ring is welded to the gasket main body by spot welding at, for example, 8 to 10 points at equal intervals, peeling occurs at the spot portion due to pressure fluctuations in the combustion chamber or the exhaust manifold. In some cases, bending or cracking may occur in the non-welded portion between the spot portions adjacent to each other, thereby reducing the sealing effect.

In order to solve such a defect, it is conceivable to attach the shim ring to the gasket body by continuous welding in the circumferential direction. In this case, the welding line for welding the shim ring is formed on a circle having a constant radius. It is formed in the circumferential direction of the through hole, and the start portion and the end portion of the welding line overlap on the circle.

However, when the start portion and the end portion of the welding line formed by the welding overlap each other on the same circle, the overlapping portion is welded twice, and furthermore,
Since the length of the heavy welded portion is relatively long, a cavity is easily formed in the double welded portion, which has a disadvantage that the sealing effect is reduced.

On the other hand, it is conceivable that the start portion and the end portion of the welding line are not continuous with each other, and the welding of the end portion is terminated before the start portion, but as a result, a gap occurs in the circumferential direction of the shim ring, Particularly under severe conditions, there is a disadvantage that the gap portion is deformed and the sealing effect is reduced.

Means for Solving the Problems In view of such circumstances, in the present invention, in a gasket having the above-described shim ring, the shim ring is attached to the gasket main body by continuous welding in a circumferential direction, and formed by the welding. The start part and the end part of the welding line cross each other.

[Operation] According to the above configuration, the shim ring can be attached to the gasket main body by continuous welding without any gap in the circumferential direction, so that the adhesion and rigidity of the welded portion are increased as compared with the case of spot welding. The peeling of the welded portion can be prevented.

Since the start portion and the end portion of the welding line are made to intersect each other, compared to a case where the start portion and the end portion overlap each other on the same circle, they are welded twice. The length of the part and the welding time can be reduced, thereby reducing the risk of cavitation.

"Example" Hereinafter, the present invention will be described with reference to the illustrated example.
In FIG. 2 and FIG. 2, the gasket includes a gasket main body 1 made of a relatively thick metal.
In addition, a combustion chamber hole 2 is formed so as to substantially match the inner diameter of a cylinder bore (not shown), and bolt holes 3 for inserting fastening bolts connecting the cylinder head and the cylinder block are formed at a plurality of locations around the combustion chamber hole 2. I have.

In addition, the gasket main body 1 does not necessarily need to be composed of one plate material, and may be formed by laminating a plurality of plate materials. Further, the bead and the shim ring may be provided on different plate members, respectively.

In the gasket main body 1, a bead portion 4 surrounding the combustion chamber hole 2 is formed so as to protrude upward and surrounds the combustion chamber hole 2, and the cylinder block and the cylinder head are defined with the bead portion 4 as a cylinder block side. Thus, the gasket main body 1 is sandwiched.

Further, on the upper surface of the gasket main body 1, the bead portion 4 is prevented from being crushed more than necessary by the cylinder head and the cylinder block, and in order to maintain a good seal by the bead portion 4 for a long time, Bead part 4
A shim ring 5 surrounding the combustion chamber hole 2 is arranged inside the inside.

The shim ring 5 is attached to the gasket body 1 by continuous welding in the circumferential direction, and most of the welding line 6 formed by the welding has a constant radius centered on the center of the combustion chamber hole 2. Yes formed on a circle of R _1, and as shown in FIG. 3, the start and end portions 6A of the weld line 6 part 6B
Are curved inward in the radial direction of the shim ring 5 and cross each other.

In this embodiment, the start point 6a of the start portion 6A is located at a position away therefrom in proximity to the inner peripheral edge of the shim ring 5, and has an arc of constant radius R _2. Also located on the remote therefrom proximate end point 6b the end portion 6B to the inner periphery of the shim ring 5 position, and has an arc of constant radius R _3.

As described above, since the start portion 6A and the end portion 6B intersect, the welding line 6 becomes continuous without leaving a gap in the circumferential direction, and the start portion 6A and the end portion 6A
6B is formed by overlapping the shim ring 5 in the circumferential direction by a predetermined distance l, and a double inner and outer welding line is formed at that portion, so that the adhesive force between the shim ring 5 and the gasket main body 1 is formed. Can be strengthened.

In the embodiment of FIG. 3, only the start portion 6A and the end portion 6B of the welding line 6 are overlapped. However, the present invention is not limited to this embodiment. By doing so, the adhesion between the gasket main body 1 and the shim ring 5 can be further increased. The overlap portion may be provided in the vicinity of a bolt where a large shear force acts due to pressure fluctuation or thermal deformation, or in the vicinity of an exhaust manifold opening.

Next, FIG. 4 is a cross-sectional view for explaining a welding operation for welding the shim ring 5 to the gasket main body 1. In the present embodiment, the same diameter as the combustion chamber hole 2 is provided at a required position on the processing table 11 of the laser welding machine. Is formed, and a plurality of bolts 13 are erected at the bottom thereof.

The cylindrical work holding member 14 has an outer diameter substantially corresponding to the inner diameter of the cylindrical concave portion 12, and has a holding portion that protrudes radially outward at the upper end thereof and holds the inner peripheral portion of the shim ring 5. 15 and a through hole 16 through which the bolt 13 is inserted. A cover 17 made of a material capable of withstanding laser beam irradiation, for example, copper, is attached to a required position of the holding portion 15,
Irradiation of the laser beam is started from above the cover 17, and the irradiation of the laser beam can be terminated (see FIG. 3).

That is, generally, when the laser processing machine starts processing by irradiating a laser beam from the focus head to the workpiece while the focus head and the workpiece are stopped,
The above processing is continued by relatively moving the focus head and the workpiece, and the laser processing is terminated by stopping the focus head and the workpiece.

Therefore, if the irradiation of the laser beam is directly started and stopped from above the shim ring 5 by omitting the cover 17, the penetration at the start point 6a and the end point 6b of the laser welding will increase, and a cavity will be formed and the seal will be formed. There is a possibility that the performance is reduced. The same applies to the case where the laser processing is started and stopped on the gasket main body 1. In this case, since the gasket main body 1 is relatively thin, a hole is formed between the start point and the end point of the laser welding. The danger increases.

However, if the inner diameter of the shim ring 5 and the inner diameter of the combustion chamber hole 2 are the same, the cover 17 can be omitted, the output of the laser beam can be changed, or the focus head and the workpiece can be moved relative to each other. In the case where laser welding is started or stopped while moving
The cover 17 can be omitted.

In the above configuration, when welding the shim ring 5 to the gasket main body 1, first, the combustion chamber hole 2 and the cylindrical recess 12 are formed.
And the gasket main body 1 is placed on the processing table 11 and the inner diameter of the combustion chamber hole 2 matches the inner diameter of the shim ring 5 so that the shim ring 5 is attached to the gasket main body 1.
Place on top. Next, while the bolt 13 is relatively inserted into the through hole 16, the lower part of the work holding member 14 is fitted into the cylindrical recess 12, and the holding part 15 above the work holding member 14 is attached to the shim ring 5. The cover 17 is placed on a predetermined position.

In this state, if the work holder 14 is fixed to the processing table 11 by tightening the nut 20 to the bolt 13, the holding part 15
Thereby, the shim ring 5 and the gasket main body 1 can be integrally fixed to the processing table 11.

After the gasket main body 1 and the shim ring 5 are fixed to the processing table 11 in this manner, the cover 17 is irradiated with a laser beam from a focus head to start laser welding. The laser beam is continuously irradiated along the circumferential direction of the shim ring 5 to perform welding while the processing table 11 and the focus head are relatively moved in a direction orthogonal to each other. When it is above, stop the irradiation.

Then, after the end of the laser welding, by loosening the nut 20 and removing the work holder 14 from the processing table 11,
The gasket body 1 to which the shim ring 5 has been welded can be removed from the processing table 11.

In addition, if necessary, a shim ring 5
May be provided, and the welding may use electron beam welding in addition to the laser welding described above.

Further, in the above embodiment, the start point 6a of the start portion 6A and the end point 6b of the end portion 6B are located close to and away from the inner peripheral edge of the shim ring 5, but conversely, close to the outer peripheral edge of the shim ring 5. Needless to say, the same effect as described above can be obtained even at a position distant therefrom.

Further, in the above-described embodiment, the irradiation of the laser beam is started and stopped on the single cover 17 provided on the holding portion 15, but when the start position and the end position are separated from each other, separate irradiation is performed. It is a matter of course that a cover may be provided on the cover.

[Effects of the Invention] As described above, in the present invention, since the shim ring is attached to the gasket main body by continuous welding in the circumferential direction, the adhesion and rigidity of the welded portion are lower than in the case of spot welding. And the peeling of the welded portion can be prevented.

In addition, since the start portion and the end portion of the welding line intersect with each other, compared to the case where the start portion and the end portion overlap each other on the same circle, welding is performed twice. The length of the portion to be welded and the welding time can be reduced, thereby reducing the risk of cavitation. Therefore, even under severe conditions, there is no possibility of deformation, and an effect that a better sealing effect can be maintained for a long time as compared with the related art can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, and FIG.
FIG. 3 is a cross-sectional view taken along the line II-II of FIG. 3, FIG. 3 is an enlarged view of a main part of FIG. 1, and FIG. 4 is a cross-sectional view for explaining a welding operation. 1 ... gasket main body, 2 ... combustion chamber hole (through hole) 5 ... shim ring, 6 ... welding line 6A ... start part, 6B ... end part 6a ... start point, 6b ... end point

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Kitamura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Shiro Inventor 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation ( 56) References JP-A-3-156155 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16J 15/08 F02F 11/00 B23K 26/00

Claims (1)

(57) [Claims] 1. A gasket having a plate-shaped gasket body provided with a through-hole serving as a high-pressure portion to be sealed, and a shim ring surrounding the through-hole attached to the gasket body, wherein the shim ring is continuous in a circumferential direction. A gasket characterized by being attached to a gasket main body by welding, and having a start part and an end part of a welding line formed by the welding cross each other.