A gasket includes a plurality of metal plates laminated together, and having a plurality of through holes situated adjacent to each other, and seal structures each annularly surrounding each of the through holes. Each of the seal structures includes a first seal bead adjacent to one through hole and a second seal bead situated outside the first seal bead relative to the one through hole, a first seal portion located in a first area between adjacent two through holes, and a second seal portion located in a second area other than the first area. The first seal portion has an annular width narrowing as outside ends of the first seal portion come close to a center of the first seal portion by locating the second seal bead close to the first seal bead, and the second seal portion has an annular width constant in an annular circumferential direction.

It is an object of the present invention to provide a sealing structure for a casing that can reduce the number of used gaskets and achieve further weight reduction, with the sealing function of the gaskets secured. The object is solved by including: a case 2 having an opened top; a cover 3 attached to the top of the case 2 to form a fluid flow path therein; a center plate 5 interposed between the case 2 and the cover 3 and partitions an inner space into the side of the case 2 and the side of the cover 3; and a gasket 4, which is disposed between the case 2 and the cover 3, and forming the center plate 5 so as to have a size that is within an inner peripheral side relative to a sealing line 41 of the gasket 4 and stacking this center plate on the gasket 4, and attaching the cover 3 to the top of the case 2 with the stacked gasket 4 and center plate 5 sandwiched there between to compress the gasket 4 with the mutual butting surfaces between the case 2 and the cover 3.

It is an object of the present invention to provide a sealing structure for a casing that can reduce the number of used gaskets and achieve further weight reduction, with the sealing function of the gaskets secured. The object is solved by including: a case 2 having an opened top; a cover 3 attached to the top of the case 2 to form a fluid flow path therein; a center plate 5 interposed between the case 2 and the cover 3 and partitions an inner space into the side of the case 2 and the side of the cover 3; and a gasket 4, which is disposed between the case 2 and the cover 3, and forming the center plate 5 so as to have a size that is within an inner peripheral side relative to a sealing line 41 of the gasket 4 and stacking this center plate on the gasket 4, and attaching the cover 3 to the top of the case 2 with the stacked gasket 4 and center plate 5 sandwiched there between to compress the gasket 4 with the mutual butting surfaces between the case 2 and the cover 3.

A gasket capable of surely preventing leakage of a fluid, without deteriorating a sealing performance even when a situation of fall of surface pressure at a periphery edge of a through hole occurs is provided. There are formed a primary seal structure 31a lying on an inner side in the radial direction of a periphery edge end 29a and a secondary seal structure 32a lying on an outer side in the radial direction of the periphery edge end 29a, in which the primary seal structure 31a includes a primary upper layer bead 33a formed to an upper layer 21, a primary intermediate layer bead 34a formed to a second plate material 28 of an intermediate layer 22 and a primary lower layer bead 35a formed to a lower layer 23 stacked in an x direction, and the secondary seal structure 32a includes a secondary upper layer bead 36a formed to the upper layer 21, an secondary intermediate layer bead 37a formed to the second plate material 28 of the intermediate layer 22 and a secondary lower layer bead 38a formed to the lower layer 23 stacked in the x direction.

A gasket includes a plurality of metal plates laminated together, and having a plurality of through holes situated adjacent to each other, and seal structures each annularly surrounding each of the through holes. Each of the seal structures includes a first seal bead adjacent to one through hole and a second seal bead situated outside the first seal bead relative to the one through hole, a first seal portion located in a first area between adjacent two through holes, and a second seal portion located in a second area other than the first area. The first seal portion has an annular width narrowing as outside ends of the first seal portion come close to a center of the first seal portion by locating the second seal bead close to the first seal bead, and the second seal portion has an annular width constant in an annular circumferential direction.

A gasket includes at least one metal plate formed of a martensitic stainless steel plate and clamped between two members fastened by fastening devices, a cylinder bore provided in the metal member, a seal bead protruding outwardly from a flat surface of the metal plate, and annularly surrounding the cylinder bore, the seal bead having a top portion and two side portions arranged at two sides of the top portion, and insertion holes for the fastening devices to pass through, provided around the cylinder bore. The seal bead has a high hardness portion having a hardness higher than that in a portion of the metal plate other than the high hardness portion. The high hardness portion has a thickness gradually reduced toward a boundary between the high hardness portion and the portion other than the high hardness portion.

A gasket includes at least one metal plate formed of a martensitic stainless steel plate and clamped between two members fastened by fastening devices, a cylinder bore provided in the metal member, a seal bead protruding outwardly from a flat surface of the metal plate, and annularly surrounding the cylinder bore, the seal bead having a top portion and two side portions arranged at two sides of the top portion, and insertion holes for the fastening devices to pass through, provided around the cylinder bore. The seal bead has a high hardness portion having a hardness higher than that in a portion of the metal plate other than the high hardness portion. The high hardness portion has a thickness gradually reduced toward a boundary between the high hardness portion and the portion other than the high hardness portion.

A gasket includes at least one metal plate to be clamped between two members fastened by fastening devices, an opening portion corresponding to a sealing hole provided in the at least one metal member, a seal bead protruding outwardly from a flat surface of the at least one metal plate, and annularly surrounding the opening portion, and insertion holes through which the fastening devices pass. At least one metal plate is formed by a martensitic stainless steel plate, and a high hardness portion having a hardness higher than that of the stainless steel plate is formed in at least one portion of the seal bead formed in the stainless steel plate.

A heat-resistant gasket is provided with a first coating plate in which an annularly continuous emboss portion is formed and which is made of metal, a second coating plate which is arranged so as to face to the first coating plate in a thickness direction and is brought into close contact with a convex surface of the emboss portion, in which end portions in an inner peripheral side of the emboss portion are connected in a state of being in close contact with and lapped over the first coating plate and which is made of metal, and an expanded graphite core which is pinched between the first coating plate and the second coating plate, in a portion between the emboss portion and the overlapped portion of the end portions. Therefore, excellent sealing performance can be maintained even under a high-temperature environment while preventing stress relaxation due to heat.

A layered head gasket includes a gasket core, a head-layer, a block-layer, and a plurality of apertures. The head gasket may be useful for sealing an internal combustion engine having a cylinder head, a cylinder block, a plurality of combustion chamber passageways, a plurality of coolant passageways, and a plurality of oil passageways. The gasket core is made of a copper sheet. The head-layer may be made of spring steel and may be fixed to a top side of the gasket core, being configured to interface with the cylinder head. Likewise, the block-layer may be made of spring steel and may be fixed to a bottom side of the gasket core, being configured to interface with the cylinder block. The plurality of apertures may pass through the head-layer, the gasket core, and the block-layer.