JP3197556B2 - Metal gasket - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a metal gasket, and more particularly to a metal gasket suitable as a cylinder head gasket, an exhaust manifold gasket, and the like for an internal combustion engine.

[Prior Art] Various gaskets are interposed between joining members in order to prevent pressure fluid from leaking from a joining surface. Various gaskets have been proposed as a cylinder head gasket interposed between a cylinder head and a cylinder block of an internal combustion engine. Recently, a metal gasket made of a metal plate, that is, a metal gasket has attracted attention. I have. For example, a plurality of holes through which a pressure fluid such as a combustion gas passes may be formed in a metal substrate, and beads may be formed in the substrate around each of the holes to secure a high surface pressure on the joining member. Such is known.

In JP-A-62-278375, JP-A-2-6855, etc., in order to prevent the bead from being plastically deformed by the tightening force and deteriorating the sealing property, the bead is projected to the metal gasket. It has been proposed to provide a surface pressure adjusting piece or a sub-plate made of a plate thinner than the height at a portion other than the bead. In Japanese Unexamined Utility Model Publication No. 2-6855, as a prior art, a metal plate is provided on a substrate on which a bead is formed, and the end of a combustion chamber hole of the metal plate is bent into a U-shape with the substrate as a core to form a grommet. When the grommet functions as a stopper for a bead subjected to repeated load due to the explosion vibration of the internal combustion engine, the metal gasket may be displaced from the substrate due to a difference in thermal expansion and vibration. As a solution. That is, the substrate has a single-plate configuration, and the sub-plate is fixed to the flat portion between the edge of the combustion chamber hole and the bead by bonding or welding.

Further, Japanese Patent Application Laid-Open No. 62-278375 discloses a method of manufacturing a metal-laminated gasket.
A method has been proposed in which another surface pressure adjusting piece is fixed by spot welding or other appropriate means, and then another gasket component plate is superposed. As a result, compared to the conventional method in which the surface pressure adjusting piece is superimposed on the gasket constituent plate by hand, the displacement of the surface pressure adjusting piece can be eliminated when the gasket constituent plate is superimposed, so that it is easily manufactured with high precision. It is possible to do.

On the other hand, U.S. Pat. No. 3,053,544 discloses a gasket in which a bead can be prevented from being plastically deformed by a double thickness portion of a main body portion of a substrate and a lip portion obtained by folding the substrate.

[Problems to be Solved by the Invention] However, merely forming the lip portion by folding the substrate as described in the above-mentioned U.S. Patent Publication, for example, a gasket used around a combustion chamber hole of an internal combustion engine has a large thermal expansion difference. There is a possibility that cracks may occur in the bent portion due to severe vibration. Also, in the conventional gasket in which a grommet is formed by bending a metal plate with respect to the above-described substrate, the same problem as described above occurs not only in the case where the displacement occurs or the spring property is deteriorated, but also in the case of the conventional gasket. obtain.

On the other hand, in the above two publications, it is proposed to fix the surface pressure adjusting piece and the sub-plate, but in the case of manufacturing these, the thin metal plate is punched in a ring shape by a press, and the yield is reduced. Bad material waste. In addition, since burrs are formed on one surface of the sub-plate at the time of pressing, the attachment direction of the sub-plate is determined when joining to the substrate, which affects productivity.

Therefore, the present invention provides a metal gasket having a folded portion at the peripheral edge of a hole of a metal substrate without causing a shift in the folded portion and, even if a crack may be generated in the bent portion, the pressure fluid can be reliably supplied. It is intended to be able to seal to.

[Means for Solving the Problems] In order to achieve the above object, the present invention perforates a hole in a metal substrate, turns the peripheral portion of the hole in the radial direction, and overlaps the main body of the substrate. A ring-shaped folded portion is formed, and the folded portion is welded to the main body of the substrate along the periphery of the hole.

[Operation] When the metal gasket having the above structure is interposed between facing joining members, for example, between a cylinder head and a cylinder block, and the two are fastened with a predetermined tightening force, the folded portion is joined. It is sandwiched between members. In this case, since the folded portion is welded to the main body of the substrate along the periphery of the hole, no deviation occurs even if there is a difference in thermal expansion between the joining members. Even if a crack occurs in the bent portion, the folded portion is firmly fixed to the main body portion by welding, so that a stable sealing property is secured without being affected by a difference in thermal expansion or the like.

Embodiment An embodiment of the metal gasket of the present invention will be described below with reference to FIGS. 1 and 2. This embodiment relates to a metal gasket applied to a cylinder head gasket interposed between a cylinder head and a cylinder block of a multi-cylinder internal combustion engine. FIG. 2 shows the bottom surface, and FIG. 1 shows a cross section taken along the line II in FIG.

The metal gasket has a substrate 10 made of an elastic metal plate, for example, a stainless steel plate.
5. A lubricating oil hole 16 and a bolt hole 17 are formed, and a bead 20 bulges around the combustion chamber hole 14. In this embodiment, the beads 20 are arranged such that the protrusions 20a are on the cylinder block (not shown) side and the recesses 20b are on the cylinder head (not shown) side.

A circular hole having a predetermined diameter is formed in the substrate 10 to form a combustion chamber hole 14 as described later, and a peripheral portion of the hole is bent toward the convex portion 20a of the bead 20 to form a folded portion 10b. Is formed. Therefore, in FIG. 1, the end face 10a of the hole faces outward. That is, as shown in FIG. 1, the substrate 10 is folded back in the radial direction of the hole (indicated by the end face 10a) to
A folded portion 10b lower than the height of 0a is formed.
The combustion chamber hole 14 is defined by the side surface of 0c. The folded portion 10b is welded to the main body 10d of the substrate 10 by a laser welding machine along the periphery of the hole (indicated by the end face 10a), that is, along the periphery of the combustion chamber hole 14. Desirably, welding is performed over the entire circumference of the ring-shaped folded portion 10b to form a substantially continuous welding line 21, and the folded portion 10b is tightly joined to the main body 10d. Further, a portion of the folded portion 10b where a crack is likely to occur, for example, a portion between the combustion chamber holes or a position separated from the bolt may be partially welded.

When a fastening force is applied to the metal gasket interposed between the cylinder block and the cylinder head in the above configuration, first, the protrusion 20a of the bead 20 comes into contact with the joining surface of the cylinder block, and the height of the bead 20 is folded back. Since the thickness is larger than the thickness of the portion 10b, the bead 20 is deformed. When the folded portion 10b is tightened between the cylinder block and the cylinder head, the deformation of the bead 20 does not proceed any more, and the bead 20 comes into close contact with both with its elastic restoring force. in this way,
The folded portion 10b forms a surface pressure adjusting portion, and a continuous side surface of the bent portion 10c is formed on the side of the combustion chamber hole 14 exposed to high temperature and high pressure. In addition, since the folded portion 10b is welded to the main body 10d along the periphery of the combustion chamber hole 14, even if a crack may be generated in the bent portion 10c, the folded portion 10b is displaced, Alternatively, there is no danger that a high-temperature and high-pressure combustion gas enters into a gap at the joint surface between the main body 10d and the turn-back portion 10b, and a stable sealing property is ensured.

FIG. 3 shows a partial cross section of a metal gasket according to another embodiment of the present invention, in which a first hole (indicated by an end face 11a) is formed in a metal substrate and a bead 20 is expanded. The formed first member 11 and a second hole (end surface 12a) are formed in a metal substrate.
) And the second member 12 having the perforated portion overlapped.
The second member 12 has a smaller plate thickness than the first member 11, and the second hole is formed to have a smaller diameter than the first hole, and is polymerized so that both are concentric. Then, the second hole peripheral portion of the second member 12 is radially folded to form a ring-shaped folded portion 12b, and the combustion chamber hole 14 is defined by the side surface of the bent portion 12c. A first member 11 is sandwiched between the folded portion 12b and the main body 12d of the second member 12, and a first hole (shown by an end face 11a).
Along the periphery of the first member 11 in the vicinity of the end face 11a.

Thus, the first and second members 11 and 12 are firmly joined to each other, and the folded portion 12b of the second member 12 shifts and falls off due to a difference in thermal expansion between the joined members as in the related art. Does not occur, and a stable sealing property is secured. Moreover, since the welding line 21 is formed on the end face 11a side, even if a crack may be generated in the bent portion 12c of the folded portion 12b, the gap between the folded portion 12b and the first member 11 may be formed. Intrusion of combustion gas and the like can be prevented. It should be noted that welding may be performed so that the welding line 21 is formed at the same position as in FIG. 1, and in the embodiment of FIG.
May be welded.

FIG. 4 shows a metal gasket according to still another embodiment of the present invention, in which a vulcanized rubber layer 30 made of vulcanized fluorine-based rubber is formed on the entire surface of a main body 10d and a folded portion 10b. I have. A sealing member 31 made of a vulcanized fluorine-based rubber is formed so as to be superimposed on the bottom edge of the projection 20 a of the bead 20 and to be continuous along the bead 20. Further, in order to secure the sealing performance at the time of joining with a cylinder block and a cylinder head (not shown), an unvulcanized or non-vulcanized rubber layer 32 is formed on all surfaces of the seal member 31, the folded portion 10b and the main body 10d. ing. Here, the non-vulcanized rubber means a rubber containing no vulcanizing agent. Unvulcanized rubber contains vulcanizing agents but has not been vulcanized. Initially, it has the same properties as unvulcanized rubber, but during use vulcanization proceeds and a strong rubber layer Is formed. The vulcanized rubber layer 30 and the seal member 31 can be formed by adding a vulcanizing agent to a fluorine-based non-vulcanized rubber, applying the vulcanizing agent on the substrate 10, and then vulcanizing by heating at a predetermined temperature. The rubber hardness of the sealing member 31 may be different from that of the vulcanized rubber layer 30, for example, by changing the degree of vulcanization or by using a different material in the same system. The remaining structure is the same as that of the embodiment shown in FIG.

Thus, as the fastening force is applied between the cylinder block and the cylinder head and the bead 20 is compressed and deformed, a compressive force is applied to the seal member 31. Then, the folded portion 10b is sandwiched between the two, and the folded portion 10b functions as a surface pressure adjusting portion for the bead 20, and at the same time, functions as a primary seal against the combustion gas by itself. Further, the bead 20 functions as a secondary seal, and the seal member 31 functions as a tertiary seal. As a result, a three-stage seal structure is eventually formed, and a stable sealing property against combustion gas is secured. In addition, since the unvulcanized or non-vulcanized rubber layer 32 is formed on the entire surface of the metal gasket, the sealing performance is not impaired even if there are minute irregularities on the joint surface between the cylinder block and the cylinder head. .

In the above embodiment, the metal gasket is a bead.
Although the 20 projections 20a are arranged on the cylinder block side, they may be reversed so that the projections 20a are arranged on the cylinder head side. Further, a metal gasket having the same configuration as that described above can be applied to an exhaust manifold gasket. Furthermore,
A laminated metal gasket can also be formed by superposing another metal substrate on the metal gasket of the above embodiment.

[Effects of the Invention] The present invention is configured as described above, and has the following effects.

That is, in the metal gasket of the present invention, a hole is formed in a metal substrate, and a peripheral portion thereof is radially folded to form a folded portion. Since it is welded, there is no deviation in the folded portion due to a difference in thermal expansion between the joining members in which the metal gasket is interposed. Even if a crack is formed in the bent portion, the folded portion is firmly joined to the main body by welding, so that the inflow of the pressure fluid is prevented, and a stable sealing property can be secured. Further, since it can be constituted by a single substrate, the number of parts is small, and there is no waste of material as in the case of manufacturing a conventional surface pressure adjusting piece or a sub-plate of another member. In addition, good thermal conductivity between the joining members can be maintained by using a single substrate.

[Brief description of the drawings]

1 is a sectional view of a part of a metal gasket according to one embodiment of the present invention, FIG. 2 is a bottom view of a part of the metal gasket, and FIG. 3 is a metal according to another embodiment of the present invention. FIG. 4 is a partial cross-sectional view of a metal gasket according to still another embodiment of the present invention. 10 ... board, 10 b ... folded part, 10 d ... body part, 14 ... combustion chamber hole, 20 ... bead, 21 ... welding wire, 11 ... first member, 12
…… the second member, 12b …… the folded part, 12d …… the body part, 30 ……
Vulcanized rubber layer, 31 Seal member, 32 Rubber layer

 ──────────────────────────────────────────────────続 き Continuing on the front page Judge of the Joint Panel Susumu Sakai Judge Hitoshi Akizuki Judge Akira Tokiwa (56) Reference JP-A-2-118274 (JP, A) JP-A-63-214571 (JP, A) JP JP-A-62-261757 (JP, A) JP-A-56-94664 (JP, A) JP-A-4-56264 (JP, U) JP-A-55-49131 (JP, U) JP-A-1-136658 (JP, A) , U) Hikaru Hei 2-43559 (JP, U)

Claims (1)

(57) [Claims] 1. A hole is formed in a metal substrate, and a peripheral edge portion of the hole is radially folded to form a ring-shaped folded portion overlapping with a main body portion of the substrate. A metal gasket, which is welded to a main body of the substrate along a periphery of the hole.