JP4069344B2 - Metal gasket - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a metal gasket used for an engine cylinder head or the like.
[0002]
[Prior art]
Conventionally, metal gaskets generally have a vulcanized rubber layer formed on a metal gasket substrate to improve the sealing performance with the cylinder head, etc., which is the counterpart material. In addition, there are also known those in which an unvulcanized rubber layer is formed (Japanese Utility Model Laid-Open No. 1-146064), and in which a vulcanized rubber layer and an unvulcanized rubber layer or a non-vulcanized rubber layer are sequentially laminated (actual (Kaiho 61-41960, JP-A-5-149435).
[0003]
[Problems to be solved by the invention]
Those in which a vulcanized rubber layer is formed on a gasket substrate are excellent in durability, but have a drawback of poor initial sealability.
On the other hand, those in which an unvulcanized rubber layer or a non-vulcanized rubber layer is formed on a gasket substrate have excellent initial sealing properties but have a problem in durability.
In addition, a vulcanized rubber layer is formed on a gasket substrate, and an unvulcanized rubber layer or a non-vulcanized rubber layer is formed on the gasket substrate. Although sealability can be obtained, there is still a problem in terms of durability.
That is, in order to form an unvulcanized rubber layer or a non-vulcanized rubber layer on a vulcanized rubber layer, a rubber liquid is prepared by dissolving the unvulcanized or non-vulcanized rubber in a solvent, and the rubber liquid is formed into a vulcanized rubber layer. Apply on top and then dry the solvent. However, the vulcanized rubber layer itself is insoluble in the solvent of the rubber liquid, but the solvent swells in the vulcanized rubber layer during application. When the solvent swells in the vulcanized rubber layer, the vulcanized rubber layer expands and the adhesion strength with the gasket substrate is reduced or peeled off, thereby reducing the durability of the metal gasket. It was.
In view of such circumstances, the present invention provides a metal gasket excellent in initial sealability and durability.
[0004]
[Means for Solving the Problems]
That is, the present invention provides a metal gasket in which a first rubber layer and a second rubber layer are sequentially laminated on a metal gasket substrate.
A barrier layer is provided between the first rubber layer and the second rubber layer to prevent the rubber solvent from passing therethrough.
In the present invention, the first rubber layer can be a vulcanized rubber layer, and the second rubber layer can be a vulcanized rubber layer, an unvulcanized rubber layer, a non-vulcanized rubber layer, or a semi-vulcanized rubber layer. It can be any of the rubber layers.
[0005]
[Action]
According to the above configuration, since the barrier layer is provided between the first rubber layer and the second rubber layer, the barrier layer prevents the rubber solvent of the second rubber layer from swelling into the first rubber layer. This can prevent the durability from decreasing.
Since the metal gasket having the above-described structure includes at least two rubber layers, ie, a first rubber layer and a second rubber layer, it is expected to have an initial sealing property superior to a metal gasket including a single rubber layer. can do.
[0006]
【Example】
An embodiment in which the present invention is applied to a cylinder head gasket of an engine will be described below. In FIG. 1, a metal gasket 1 includes three metal gasket substrates 2, 3, and 4 that are superposed on each other. The central gasket substrate 2 is thicker than the other gasket substrates 3 and 4, but is formed in a flat plate shape. On the other hand, the other thin gasket substrates 3 and 4 superposed on the upper and lower surfaces of the central gasket substrate 2 are provided with full bead portions 3 a and 4 a protruding toward the central gasket substrate 2.
Each of the gasket substrates 2 to 4 is provided with a combustion chamber hole 5 drilled in accordance with an engine cylinder bore (not shown), and the full bead portions 3a and 4a are formed so as to surround the combustion chamber hole 5. .
The rubber layer 6 is formed on the upper and lower surfaces of the central gasket substrate 2, but the other thin gasket substrates 3 and 4 have a rubber layer only on the outer surface with respect to the central gasket substrate 2. 6 is formed.
[0007]
Since each of the rubber layers 6 has the same configuration, the configuration of the rubber layer 6 formed on the upper surface of the central gasket substrate 2 will be described. As shown in an enlarged view in FIG. The primer layer 7 formed on the upper surface of the gasket substrate 2, the first rubber layer 8 formed on the primer layer 7, the barrier layer 9 formed on the first rubber layer 8, and the barrier layer 9 The second rubber layer 10 is formed.
The primer layer 7 is provided in order to increase the adhesion strength between the gasket substrate 2 and the first rubber layer 8. As the primer layer 7, for example, a material such as organic silicon can be used.
[0008]
The first rubber layer 8 is formed of a vulcanized rubber layer, and as the first rubber layer 8, NBR, HNBR, fluorine rubber, or the like can be used.
On the other hand, the second rubber layer 10 is any one of a vulcanized rubber layer, an unvulcanized rubber layer, a non-vulcanized rubber layer, or a semi-vulcanized rubber layer. , HNBR, fluorine rubber, or the like can be used.
For the second rubber layer 10, it is desirable to select an unvulcanized rubber layer or a non-vulcanized rubber layer in consideration of the initial sealability with a mating material such as another gasket substrate or cylinder head. However, even when a vulcanized rubber layer or a semi-vulcanized rubber layer is used, since the rubber layer 6 includes the first rubber layer 8 and the second rubber layer 10, a single rubber layer is formed. Compared to the case where it is provided, it becomes easy to ensure an excellent initial sealing property. For example, fluororubber is selected as the first rubber layer 8, NBR is selected as the second rubber layer 10, hard rubber is selected as the first rubber layer 8, soft rubber is selected as the second rubber layer 10, and both rubber layers 8 are selected. By vulcanizing 10, excellent initial sealing properties and durability can be ensured.
[0009]
The vulcanized rubber layer refers to a rubber layer that has been fully vulcanized with sufficient vulcanizing agent added. The unvulcanized rubber layer refers to a vulcanized agent that has been added with vulcanizing agent. This refers to a rubber layer that has not been used. Further, the non-vulcanized rubber layer refers to a rubber layer to which no vulcanizing agent is added, and the semi-vulcanized rubber layer refers to a vulcanized agent that has been added with a vulcanizing agent. A rubber layer that has not been completely vulcanized.
[0010]
Next, when the second rubber layer 10 is formed, the barrier layer 9 has a function of preventing the rubber solvent of the second rubber layer 10 from passing through the first rubber layer 8 that has already been formed. is doing.
That is, as described above, an unvulcanized rubber layer or a non-vulcanized rubber layer that is the second rubber layer 10 is formed on the vulcanized rubber layer that is the first rubber layer 8 without forming the barrier layer 9, Alternatively, when a rubber layer before vulcanization is formed to form a vulcanized rubber layer or a semi-vulcanized rubber layer as the second rubber layer 10, the rubber solvent of the second rubber layer 10 swells in the first rubber layer 8. To come. Then, the first rubber layer 8 expands and the adhesion strength with the gasket substrate 2 decreases or peels off, resulting in a decrease in durability of the metal gasket.
On the other hand, if the barrier layer 9 is formed, the rubber solvent of the second rubber layer 10 is prevented from permeating into the first rubber layer 8, so that the adhesion strength between the first rubber layer 8 and the gasket substrate 2 is increased. Can be prevented, thereby preventing the durability of the metal gasket from being lowered.
Further, the barrier layer 9 prevents the cooling water or the long life coolant that has permeated through the unvulcanized rubber layer or the non-vulcanized rubber layer from reaching the first rubber layer 8, so that the durability is also improved in this respect. Can be achieved.
[0011]
The meaning that the barrier layer 9 prevents the rubber solvent of the second rubber layer 10 from permeating to the first rubber layer 8 does not mean that the rubber solvent completely permeates. If the durability of the metal gasket can be prevented from being lowered, a slight solvent permeation is allowed. As a practical matter, the barrier layer 9 cannot completely prevent the rubber solvent from permeating due to pinholes or the like generated when the barrier layer 9 is formed.
[0012]
As described above, the barrier layer 9 only needs to have a function of preventing the rubber solvent from permeating, and desirably has heat resistance to withstand the vulcanization temperature. In addition, wetting with the rubber solvent is also necessary. As a material having such a function, for example, a silicon resin, a butadiene resin, an imide resin, an amide resin, an amideimide resin, an epoxy resin, or a phenol resin can be used.
Further, a non-adhesive resin or solid lubricant such as graphite, fluororesin, BN, polyethylene, or MoS ₂ may be added to the barrier layer 9. Since these have non-adhesiveness, the adhesive force between the barrier layer 9 and the second rubber layer 10 can be controlled by the amount of addition.
Therefore, the second rubber layer 10 can be transferred to the counterpart material rather than the barrier layer 9, and in this case, due to the difference in thermal expansion coefficient or the explosion pressure between the second rubber layer 10 and the barrier layer 9. The movement can be absorbed, and the metal gasket 1 can be separated between the second rubber layer 10 and the barrier layer 9 when the cylinder head and the cylinder block are disassembled.
[0013]
【The invention's effect】
As described above, according to the present invention, the barrier solvent can prevent the rubber solvent of the second rubber layer from swelling into the first rubber layer, so that it is possible to prevent a decrease in durability due to swelling. Since at least two rubber layers of the first rubber layer and the second rubber layer are provided, it is easy to ensure an initial sealing property superior to a metal gasket having a single rubber layer. can get.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Metal gasket 2, 3, 4 ... Gasket board | substrate 6 ... Rubber layer 7 ... Primer layer 8 ... 1st rubber layer 9 ... Barrier layer 10 ... 2nd rubber layer

Claims (3)

In the metal gasket in which the first rubber layer and the second rubber layer are sequentially laminated on the metal gasket substrate,
A gasket comprising a barrier layer for preventing a rubber solvent from passing between the first rubber layer and the second rubber layer. The first rubber layer is composed of a vulcanized rubber layer, and the second rubber layer is any one of a vulcanized rubber layer, an unvulcanized rubber layer, a non-vulcanized rubber layer, or a semi-vulcanized rubber layer. The metal gasket according to claim 1. The metal gasket according to claim 1 or 2, wherein each of the first rubber layer and the second rubber layer is one of NBR, HNBR, or fluororubber.

Images