JPH04165166A - Metal gasket - Google Patents

Abstract

PURPOSE:To prevent the generation of dislocation to a folded part so as to seal a pressure fluid positively even with the generation of a crack to a bent part by folding the peripheral edge part of a hole bored in a metal base radially so as to be overlapped with the body part of the base, and welding the folded part to the body part along the peripheral edge of the hole. CONSTITUTION:A metal gasket is provided with a base 10 made of an elastic metal plate, and the peripheral edge part of a hole bored to form a combustion chamber hole 14 is folded onto the protruding part 20a side of a bead 20 to form a folded part 10b. The folded part 10b is welded, along the hole peripheral edge, to the body part 10d of the base 10 by a laser welding machine so as to form a substantially continuous weld line 21 and the folded part 10b is adhesively jointed to the body part 10d. Accordingly, even if a crack is generated to a bent part 10c, there is no fear of dislocation being generated to the folded part 10b or an interstice being generated to a joint face between the body part 10 and the folded part 10b to cause the admission of high-temperature high-pressure combustion gas, so that stable sealing performance is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a metal gasket, and particularly to a metal gasket suitable as a cylinder head gasket, an exhaust manifold gasket, etc. of an internal combustion engine.

[Prior Art] Various gaskets are interposed between joint members to prevent pressure fluid from leaking from the joint surfaces.

Various gaskets have been proposed as cylinder head gaskets that are interposed between the cylinder head and cylinder block of internal combustion engines, but recently metal gaskets made of metal plates have attracted attention. ing. For example, a plurality of holes through which pressurized fluid such as combustion gas passes can be bored in a metal substrate, and a bead can be formed in the substrate around each hole to ensure high surface pressure against the joining member. It is known that this was done.

And, Japanese Patent Application Laid-open No. 62-278375, Utility Model Application No. 1-
In Publication No. 6855, etc., in order to avoid plastic deformation of the bead due to tightening force and deterioration of sealing performance, a surface pressure adjusting piece or sub-plate made of a plate thinner than the protruding height of the bead is attached to the metal gasket. It has been proposed to install it in other parts. In Japanese Utility Model Application Publication No. 2-6855, as a conventional technique, a metal plate is provided on a substrate on which a beat is formed, and the end of the combustion chamber hole of this metal plate is bent into a U-shape with the substrate as the center to form a grommet. When the grommet functions as a stopper for the bead, which is subjected to repeated loads due to the explosion vibrations of an internal combustion engine, the stiffness of the metal gasket is bent due to the difference in thermal expansion and vibration, and the gasket becomes detached from the board. This is a possible problem and we are proposing a solution. That is, the substrate has a single-plate structure, and the sub-plate is fixed to the flat part between the combustion chamber hole edge and the heat by adhesion or welding.

Furthermore, in Japanese Patent Application Laid-Open No. 62-278375, metal f'i! [Regarding the manufacturing method of layered gaskets, we have proposed a method in which a surface pressure adjusting piece, which is a separate member, is attached to the gasket component plate using spot welding or other appropriate means, and then other gasket component plates are superimposed. has been done. As a result, compared to the conventional method in which the surface pressure adjustment piece was manually superimposed on the gasket component plate, it is possible to eliminate the misalignment of the surface pressure adjustment piece when superimposing the gasket component plate, making manufacturing easier with high precision. It is said that it is possible.

On the other hand, US Pat. No. 3,053,544 discloses a gasket in which plastic deformation of the beat can be prevented by a double-thickness portion of the main body portion of the substrate and the lip portion formed by folding back the substrate.

[Problems to be Solved by the Invention] However, simply forming the lip portion by folding back the substrate as described in the above-mentioned U.S. patent publication would result in large thermal expansion, for example, in a gasket used for opening the combustion chamber of an internal combustion engine. There is a risk of cracking at the bent part due to the difference and strong vibration. In addition, with the conventional gasket in which the grommet was formed by bending a metal plate with respect to the above-mentioned substrate, problems similar to those described above occurred, as well as simply misalignment or deterioration of the spring properties. obtain.

On the other hand, the above-mentioned two publications propose fixing a surface pressure adjustment piece or a sub-plate, but when manufacturing these, a thin metal plate is punched into a ring shape using a press, which reduces the yield. Unfortunately, this results in wasted materials. Furthermore, since a firmness is formed on one side of the sub-plate during pressing, the attaching direction of the sub-plate is regulated when bonding to the substrate, which affects productivity.

Therefore, the present invention provides a metal gasket that has a folded part at the periphery of a hole in a metal substrate, so that the folded part does not shift and even if a crack occurs in the folded part, the pressurized fluid is ensured. The purpose is to make it possible to seal it.

[Means for Solving the Problems] 1) In order to achieve the above object, the present invention provides a hole in a metal substrate, a peripheral edge of the hole is folded back in the radial direction, and a hole is formed in the main body of the substrate. A ring-shaped folded portion that overlaps is formed, and the folded portion is welded to the main body portion of the substrate along the periphery of the hole.

Further, a first member having a first hole formed in a metal substrate and a bead bulgingly formed at the opening of the first hole, and a first member formed in a metal substrate different from the first member. a second member having a second hole having a smaller diameter than the first hole and superimposed on the first member so that the second hole and the first hole are concentric; The peripheral edge of the second hole of the second member is folded back in the radial direction to form a ring-shaped folded part, and the first hole is formed between the folded part and the main body of the second member. The folded portion may be welded to the first member along the periphery of the first hole by sandwiching the periphery.

[Operation] When the metal gasket having the above structure is interposed between opposing joining members, for example between the cylinder head and the cylinder block, and the two are fastened with a predetermined tightening force, the folded portions are joined. It is held between members. In this case, since the folded portion is welded to the main body portion of the substrate along the peripheral edge of the hole, there will be no misalignment 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 by welding, so stable sealing performance is ensured without being affected by differences in thermal expansion, etc.

[Example] Hereinafter, an example of the metal gasket of the present invention will be described with reference to FIGS. 1 and 2. This embodiment relates to a metal gasket applied to a cylinder rad gasket interposed between a cylinder head and a cylinder block of a multi-cylinder internal combustion engine. FIG. 2 shows its bottom surface, and FIG. 1 shows a cross section taken along line I-1 in FIG.

The metal caskerat has a substrate 10 made of an elastic metal plate, for example, a stainless steel plate, and a combustion chamber hole 14, a cooling water hole 15, a lubricating oil hole 16, and a hole 17 are formed in this substrate 10, and a hole around the combustion chamber hole 14 is formed. A bead 20 is formed in a bulging manner. In this embodiment, the bead 20 is arranged such that the convex portion 20a is on the cylinder block (not shown) side and the concave portion 20b is on the cylinder head (not shown) side.

A circular hole of a predetermined diameter is bored in the substrate 10 in order to form a combustion chamber hole 14, as will be described later.
is formed. Therefore, in Fig. 1, the end face 1 of the hole
0a 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 surface 10a) to form a folded part 10b that is lower in height than the convex part 20a of the bead 20.
is formed, and the combustion chamber hole 14 is defined by the side surface of the bent portion 10c. Then, the folded portion iob is formed along the periphery of the hole (indicated by the end surface 10a), that is, along the periphery of the combustion chamber hole 14, using a laser welder to form the main body portion 10d of the substrate 10.
is welded to. Desirably, a ring-shaped folded portion 10
A substantially continuous welding line 21 that is welded over the entire circumference of b.
is formed, and the folded part fob is closely joined to the main body part 10d. Further, portions of the folded portion 10b where cracks are likely to occur, for example, between the combustion chamber holes and at a position distant from the bolt, may be partially welded.

When the above-mentioned configuration is adopted and a fastening force is applied to the metal gasket interposed between the cylinder block and the cylinder head, the convex portion 20a of the bead 20 first comes into contact with the joint surface of the cylinder block, and the height of the bead 20 is folded back. The bead 20 is deformed because it is larger than the thickness of the portion 10b. When the folded portion 10b is tightened between the cylinder block and the cylinder head, the bead 20 will not deform any further and will come into close contact with both using its elastic restoring force. In this way, the folded portion tab constitutes a surface pressure adjusting portion, and the folded portion 1
A continuous side surface of 0c is formed. Moreover, the folded part 10
b is welded to the main body part 10d along the periphery of the combustion chamber hole 14, so even if a crack were to occur in the bent part 10c, the folded part 10b would be misaligned, or the main body part 10d There is no fear that a gap will be formed at the joint surface of the folded portion 10b and that high temperature and high pressure combustion gas will enter the gap, and stable sealing performance can be ensured.

FIG. 3 shows a cross section of a part of a metal gasket according to another embodiment of the present invention, which is attached to a metal substrate.

A first member 11 in which a first hole (indicated by end surface 11a) is formed and a bead 20 bulges out, and a second member 11 in which a second hole (indicated by end surface 12a) is formed in a metal substrate. Part 1 of
2 are polymerized. The second member 12 is the first member 1
The plate thickness is thinner than that of the first hole, the second hole is formed to have a smaller diameter than the first hole, and the two holes are overlapped so that they are concentric. Then, the second hole peripheral portion of the second member 12 is folded back in the radial direction to form a ring-shaped folded portion 12b.
A combustion chamber hole 14 is defined by the side surface c. The first member 11 is held between this folded portion 12b and the main body portion 12d of the second member 12, and the first member 11 is held near the end surface 11a of the first member 11 along the periphery of the first hole (end surface 11a not shown). be welded to.

As a result, the first and second members 11 and 12 are firmly joined, and unlike the prior art, the folded portion 12b of the second member 12 does not shift and fall off due to the difference in thermal expansion between the joined members. This ensures stable sealing performance. Furthermore, since the weld line 21 is formed on the end surface 11a side, even if a crack occurs in the bent portion 12c of the folded portion 12b, there will be no damage between the folded portion 12b and the first member 11. Entry of combustion gas, etc. can be prevented. It should be noted that welding may be performed so that the weld line 2 is formed at the same position as in FIG. 1, and in the embodiment shown in FIG. It may be welded to

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 fluororubber is formed on the entire surface of the main body portion 10d and the folded portion 10b. There is. A seal member 31 made of vulcanized fluororubber is formed so as to overlap the hem edge of the convex portion 20a of the bead 20 and continue along the bead 20. Furthermore, in order to ensure sealing performance when joining with a cylinder block and a cylinder head (not shown), a sealing member 31 and a folded portion 1 are provided.
An unvulcanized or unvulcanized rubber layer 32 is formed on the entire surface of the main body portion 10d. Here, non-vulcanized rubber refers to rubber that does not contain a vulcanizing agent. Unvulcanized rubber contains a vulcanizing agent but has not been vulcanized. Initially, it has the same characteristics as unvulcanized rubber, but as it is used, it progresses to vulcanization and develops a strong rubber layer. is formed. The vulcanized rubber layer 30
and seal member 3] can be formed by adding a vulcanizing agent to fluorine-based non-vulcanized rubber, applying the mixture onto the substrate 10, and then heating and vulcanizing it at a predetermined temperature. The sealing member 31 may have a different rubber hardness from the vulcanized rubber layer 30 by, for example, changing the degree of vulcanization or by using different materials in the same system. The rest of the structure is the same as the embodiment shown in FIG.

As the fastening force is applied between the cylinder block and the cylinder head and the bee F 20 is compressively deformed, a compressive force is applied to the seal member 31. Then, the folded part 10b
is held between the two, and the folded portion 10b maintains the sealing function of the bead 20 as a surface pressure adjusting portion against the bead 20, and functions as a primary seal against combustion gas by itself. Furthermore, the bead 20 functions as a secondary seal and the seal member 31 functions as a tertiary seal, resulting in a three-stage seal structure, ensuring stable sealing performance against combustion gas. Moreover, since the unvulcanized or non-vulcanized rubber layer 32 is formed on the entire surface of the metal gasket, the sealing performance will not be impaired even if there are minute irregularities on the joint surface of the cylinder block and cylinder head. .

In addition, in the above embodiment, the metal gasket is bead 2.
Although the convex portion 20a of No. 0 is disposed on the cylinder block side, it may be reversed and disposed so that the convex portion 20a is on the cylinder head side. Further, it is also possible to apply a metal gasket having the same configuration as above to the exhaust manifold gasket. Furthermore, a laminated metal gasket can be constructed by superimposing another metal substrate onto the metal gasket of the above-described embodiment.

[Effects of the Invention] Since the present invention is configured as described above, it produces the effects described below.

That is, in the metal gasket of the present invention, a hole is formed in a metal substrate, the periphery of the hole is folded back in the radial direction to form a folded portion, and this is then inserted into the main body of the substrate along the periphery of the hole. Since it is welded, there will be no misalignment of the folded portion due to differences in thermal expansion between the joining members interposed with the metal gasket. Even if a crack were to occur in the bent portion, the folded portion is firmly joined to the main body portion by welding, which prevents pressure fluid from entering and ensures stable sealing performance. In addition, since it can be constructed from 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 adjustment piece or sub-plate as a separate member. Moreover, by using a single substrate, it is possible to maintain good thermal conductivity between the bonding members.

In a metal gas kerator having a first member with a bead formed and a second member with a folded part, the first and second members are welded at the folded part, so the heat between the joined members is There is no misalignment between the first and second members due to differences in expansion, etc., and even if a crack should occur in the bent portion, stable sealing performance can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a part of a metal gasket according to an embodiment of the present invention, FIG. 2 is a bottom view of a part of the metal gasket, and FIG. 3 is a cross-sectional view of a part of a metal gasket according to another embodiment of the invention FIG. 4 is a cross-sectional view of a portion of a metal gasket according to still another embodiment of the present invention. 10... Board, 10b... Folded part, 10d... Main body part. 14... Combustion chamber hole, 20... Bead, 21... Welding line. 11... first member, 12... second member, 12b
... Folded portion 112d... Main body part, 30... Vulcanized rubber layer.

Claims (2)

[Claims] (1) A hole is bored in a metal substrate, and the peripheral edge of the hole is folded back in the radial direction to form a ring-shaped folded portion that overlaps with the main body of the substrate, and the folded portion is folded around the hole. A metal gasket characterized in that the metal gasket is welded to the main body of the substrate along the periphery. (2) A first member in which a first hole is bored in a metal substrate and a bead is formed around the first hole, and a first member is formed in a metal substrate different from the first member. a second member having a second hole having a smaller diameter than the first hole and superimposed on the first member so that the second hole and the first hole are concentric; The peripheral edge of the second hole of the second member is folded back in the radial direction to form a ring-shaped folded part, and the first hole is formed between the folded part and the main body of the second member. A metal gasket characterized in that the folded part is welded to the first member along the peripheral edge of the first hole with the peripheral edge thereof being sandwiched.