Hereunder, embodiments of a gasket according to the present invention which are applied to a cylinder head gasket placed between a cylinder head and a cylinder block for an internal-combustion engine will be described in detail with reference to the attached drawings.
The cylinder head gasket 2 is composed of a single metal plate 4, and as shown in
A periphery bead 20 formed by a full bead is provided on the surface of the metal plate 4, which is pressed on the cylinder head (not shown in the figure), and a seal bead 22 formed by a full bead is provided around the combustion chamber hole 10.
Conductivity portions 24A, 24B for assuring electrical conductivity between the cylinder head and the cylinder block are provided on the respective surfaces of the metal plate 4, which are pressed on the cylinder head and the cylinder block. More specifically, on the surface of the metal plate 4 which is pressed on the cylinder head, the top portion 20a of the periphery bead 20 which is more projected than other flat portions becomes the conductivity portion 24A. On the other hand, on the surface which is pressed on the cylinder block, a larger load acts on the bottom portion 20b of the periphery bead 20, as compared to other areas, by a load distribution when the gasket 2 is placed between the cylinder head and the cylinder block and tightened by the tightening bolt. As a result, the bottom portion 20b can be the conductivity portion 24B.
Seal materials 26A, 26B for assuring a seal quality are coated at the seal-required portions of the respective surfaces of the metal plate 4, except for at least the conductivity portions 24A, 24B which are pressed on the cylinder head and the cylinder block, i.e. a part of the periphery bead 20, around the combustion chamber hole 10 including the seal bead 22 and around the fluid holes 14.
Incidentally, the seal materials 26A, 26B are coated on the metal plate 4 constituting the gasket 2 after the combustion chamber hole 10, the bolt holes 12, the fluid holes 14, the periphery bead 20, and the seal bead 22 are processed. The reason is that if a metal plate whose seal materials are preliminarily coated is used, a special process is required for assuring stable electrical conductivity.
In the gasket 2 with the above-mentioned structure, the conductivity portions 24A, 24B for assuring the electrical conductivity between the cylinder head and the cylinder block are provided on the respective surfaces of the metal plate 4 constituting the gasket 2, which are pressed on the cylinder head and the cylinder block. Accordingly, when the stable electrical conductivity between the cylinder head and the cylinder block is required, the gasket 2 can reliably provide stable electrical conductivity.
Also, the seal materials 26A, 26B are coated on the seal-required portions of the respective surfaces of the metal plate 4, except for at least the conductivity portions 24A, 24B, which are pressed on the cylinder head and the cylinder block. Accordingly, a seal quality between the cylinder head and the cylinder block can be reliably assured.
In addition, the seal materials 26A, 26B are coated on the metal plate 4 constituting the gasket 2 after the combustion chamber hole 10, the bolt holes 12, the fluid holes 14, the periphery bead 20, and the seal bead 22 are processed. Accordingly, the stable electrical conductivity between the cylinder head and the cylinder block can be reliably assured.
Next,
The main structure of the cylinder head gasket 32 of the second embodiment is the same as that of the first embodiment. However, as shown in
Here, other structures and operations of the second embodiment are substantively the same as those of the first embodiment, so that the same symbols are used for the same portions or corresponding portions, and the explanations are omitted.
Incidentally, in each embodiment, the case wherein the present invention is applied to the gasket formed by a single metal plate is explained; however, the present invention is not limited to the above-mentioned case, and can also be applied to a metal-laminated gasket formed by laminating plural metal plates.
In this case, as in the cases of the first embodiment and the second embodiment, the top portion and the bottom portion of the bead, or the folded portion around the metal plate can be a conductivity portion. However, for example, a positioning projection for preventing misalignment between the laminated metal plates and determining the position of the metal plates can be constituted as a current-carrying projection, or a projection for carrying current can be separately provided and this portion can be a current-carrying portion between the two members.
The disclosure of Japanese Patent Application No. 2006-134260, filed on May 12, 2006, is incorporated in the application. While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.
Number | Date | Country | Kind |
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2006-134260 | May 2006 | JP | national |