JP2712659B2 - gasket - Google Patents

Description

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

Conventionally, conventionally, as a gasket of this type, a plate-shaped gasket body is provided with a through hole serving as a high-pressure portion to be sealed, and a bead portion and a shim ring surrounding the through hole are formed on the gasket body. A concentric arrangement is known (Japanese Utility Model Laid-Open No. 59-188955).

The bead portion is sandwiched between, for example, a cylinder head and a cylinder block, closely adheres to them, and seals the portion well. On the other hand, the shim ring is provided for the purpose of preventing the bead portion from being unnecessarily crushed by the cylinder head and the cylinder block, and maintaining good sealing by the bead portion for a long time.

"Problems to be Solved by the Invention" By the way, when the shim ring is welded to the gasket body by spot welding at, for example, 8 to 10 points at equal intervals, the spot portion is separated due to pressure fluctuations in the combustion chamber and 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 particular, this tendency was remarkable when the shim ring was disposed inside the bead portion, that is, on the side of the through-hole serving as the high-pressure portion.

In order to solve such a defect, it is conceivable to attach the shim ring to the gasket main body by continuous welding in the circumferential direction. However, if the start portion and the end portion of the welding line formed by the welding are made continuous with each other, the continuous portion is welded twice, so that a cavity is easily formed in that portion, This has the disadvantage that the sealing effect is reduced.

On the other hand, if 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, a gap is generated 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, the present invention attaches the shim ring to the gasket main body by continuous welding in the circumferential direction in the above-described gasket, and further includes a welding line formed by the welding. The start portion and the end portion are formed so as not to be continuous with each other but to overlap in the circumferential direction of the shim ring.

[Operation] According to the above configuration, the shim ring can be attached to the gasket main body by continuous welding in the circumferential direction, so that the adhesion and rigidity of the welded portion are increased as compared with the case of spot welding, and the welding is performed. Partial separation can be prevented.

In addition, since the start portion and the end portion of the welding line are not continuous with each other, there is no room for generating a cavity when the both portions are connected, and furthermore, both portions are arranged in the circumferential direction of the shim ring. Because it is formed by overlapping,
There is no circumferential gap between the two parts, and therefore, even under severe conditions, the gap is less likely to be deformed, and a better sealing effect can be maintained for a longer time than in the past. It becomes possible.

"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 in a plurality of locations around the combustion chamber hole 2. I have. The gasket main body 1 does not necessarily need to be formed of a single plate, but may be formed by laminating a plurality of plates. 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 around the combustion chamber hole 2, and a top portion of the bead portion 4 is elastically contacted with a cylinder block. On the upper surface of the gasket main body 1, a shim ring 5 surrounding the combustion chamber hole 2 is disposed inside the bead portion 4, and the shim ring 5 is attached to the gasket main body 1 by continuous welding in a circumferential direction. Starting portion 6A of welding line 6 formed by the welding
And the end portion 6B, without being continuous with each other, and
The shim ring 5 is formed so as to overlap the circumferential direction of the shim ring 5 by a predetermined distance 1 (see FIG. 3).

FIG. 3 is an enlarged view of a start portion 6A and an end portion 6B of the welding line 6 of the shim ring 5, and in this embodiment, the starting point 6a of the start portion 6A is close to the inner peripheral edge of the shim ring 5, and located away, and has an arc of constant radius R _1. On the other hand, the end point 6b the end portion 6B is in a position away therefrom in close proximity to the outer peripheral edge of the shim ring 5, and has an arc of constant radius R _2. The start portion 6A and the end portion 6B have a radius R ₃ centered on the center of the combustion chamber hole 2.
Interconnected above.

If possible, the start portion 6A and the end portion 6B may be located at positions that are less susceptible to thermal effects in the combustion chamber hole 2, specifically, positions that are away from the exhaust valve, and combustion positions adjacent to each other. It is desirable to provide at a position away from the middle position of the chamber hole.

FIG. 3 shows an embodiment in which the welding line 6 has a start portion 6A and an end portion.
Although only 6B is overlapped (distance 1), this distance 1 is not necessarily limited to this embodiment, and the welding line 6 may be overlapped by about a half turn to be the distance l. In this case, the overlap portion is the gasket body 1
Because of the strong adhesion between the shaft and the shim ring 5, it may be provided in a position opposite to that of the embodiment of FIG. 3, that is, in the vicinity of a bolt or an exhaust manifold opening where a large shear force acts due to pressure fluctuation or thermal deformation. it can.

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 circumferential 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 a laser beam can be started from above the cover 17 (see FIG. 3).

On the other hand, a plate 18 is provided outside the shim ring 5 and beyond the outer peripheral edge of the shim ring 5, and the plate 18 is attached to the processing table 11 by bolts (not shown). Then, a cover 19 for covering the upper part of the outer peripheral portion of the shim ring 5 is attached to the plate 18 at a position substantially opposed to the cover 17, so that the irradiation of the laser beam can be terminated on the cover 19 (third). See figure).

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 started and terminated directly from above the shim ring 5 by omitting the covers 17 and 19, penetration at the start point 6a and the end point 6b of laser welding increases, and a cavity is formed. Therefore, there is a possibility that the sealing property 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, when the inner diameter of the shim ring 5 and the inner diameter of the combustion chamber hole 2 are the same, the cover 17 on the inner diameter side can be omitted,
In addition, when the output of the laser beam is changed, or when the laser welding is started or stopped while the focus head and the workpiece are relatively moved, the covers 17 and 19 are omitted. It is possible to do.

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, the lower part of the work holder 14 is fitted into the cylindrical recess 12 while the bolt 13 is relatively inserted into the through hole 16, and the holding part 15 above the work holder 14 is 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.

Next, a plate is placed at a predetermined position outside the shim ring 5.
When the cover 18 provided on the plate 18 is disposed at a predetermined position substantially opposed to the cover 17, the plate 18 is fixed to the working table 11 with bolts (not shown).

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 moving the processing table 11 and the focus head in directions perpendicular to each other. When it is above, stop the irradiation.

After the laser welding is completed, the bolt is loosened to remove the plate 18 from the processing table 11, and the nut 20 is loosened to remove the work retainer 14 from the processing table 11, whereby the gasket to which the shim ring 5 is welded is removed. The main body 1 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.

[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 are not continuous with each other, there is no room for generating a cavity when the both portions are connected, and furthermore, both portions are arranged in the circumferential direction of the shim ring. Since they are formed in an overlapping manner, there is no circumferential gap between the two parts. Therefore, even under severe conditions, the gaps are less likely to be deformed. The effect is that a good sealing effect can be maintained for a long time.

[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. 1 ... gasket main body, 2 ... combustion chamber hole (through hole) 4 ... bead part, 5 ... shim ring 6 ... welding line, 6A ... start part 6B ... end part, 6a ... start point 6b ... End point, l ... overlap distance

Continuation of the front page (72) Inventor Shiro Kawai 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (56) References Japanese Utility Model Showa 60-1445663 (JP, U)

Claims (1)

(57) [Claims] 1. A gasket comprising: a plate-shaped gasket body having a through hole serving as a high-pressure portion to be sealed; and a bead portion surrounding the through hole and a shim ring concentrically provided in the gasket body. The shim ring is attached to the gasket body by continuous welding in the circumferential direction, and the start part and the end part of the welding line formed by the welding are overlapped in the circumferential direction of the shim ring without being continuous with each other. A gasket characterized by being formed by: