Sealing structure using metal gasket
A metal gasket has a primary bead formed on an area positioned between a cylinder bore and a cooling water passage. A second bead is formed on an area corresponding to an opening of one or more cooling passages. A base member of the metal gasket comprises bead plates that have a rubber coating layer. The base member also comprises a shim member disposed between the bead plates. The primary bead is formed by defining a space respectively between the bead plates and the shim member. The secondary bead is formed by defining a space on a given area between the bead plates.
1. A metal gasket for sealing an interface between a cylinder head and a cylinder body of an engine body, the metal gasket comprising:
first and second bead plates, each of the first and second bead plates including:
a plurality of primary beads arranged to protrude outward;
a secondary bead arranged to protrude outward, the secondary bead including an inner side adjacent to the plurality of primary beads and an outer side spaced from the inner side;
a plurality of cylinder openings;
a plurality of cooling water holes;
an exhaust gas hole; and
a plurality of exhaust cooling water holes arranged around the exhaust gas hole, wherein the plurality of cylinder openings are arranged in a row and the exhaust gas hole is offset from the row of the plurality of cylinder openings; and
an inner member disposed between at least a portion of the first and second bead plates, the plurality of primary beads are defined by the first and second bead plates and the inner member disposed between the first and second bead plates, and the secondary bead is defined by the first and second bead plates and partially by the inner member such that the inner member is located at an inner side of the secondary bead that is adjacent to the plurality of primary beads but only the first and second bead plates and not the inner member are located at an outer side of the secondary bead; wherein
the plurality of primary beads are full beads arranged adjacent to a periphery of the plurality of cylinder openings, respectively;
the secondary bead is positioned on an opposite side of the plurality of primary beads from the plurality of cylinder openings;
the secondary bead surrounds all of the plurality of primary beads;
the secondary bead has a plateau shape including a plateau portion and bent portions extending to the plateau portion, the plateau portion of the secondary bead defines an outermost layer of the metal gasket, and the plurality of cooling water holes are located in the plateau portion of the secondary bead between the inner side and the outer side of the secondary bead; and
the metal gasket includes three half beads arranged between the exhaust gas hole and an outer periphery of the metal gasket, a first of the three half beads is disposed such that an open end of the first half bead is positioned at the outer periphery of the metal gasket, and a second and a third of the three half beads are positioned such that open ends of the second and third half beads are positioned at an inner periphery of at least one of the plurality of exhaust cooling water holes.
2. The metal gasket of claim 1 , wherein each of the plurality of primary beads and the secondary bead is left-right symmetrical about a vertical line extending through a center of the plurality of primary beads and the secondary bead, respectively.
3. The metal gasket of claim 1 , wherein each of the plurality of primary beads and the secondary bead is top-bottom symmetrical about a horizontal line extending between the first and second bead plates.
4. The metal gasket of claim 1 , wherein the inner member is made of stainless steel and includes a rubber coating layer provided on at least one of its surfaces.
5. The metal gasket of claim 4 , wherein a gap filler is arranged on at least a portion of an outermost surface of at least one of the first and second bead plates at a location corresponding to the secondary bead so as to protrude from the outermost surface of the at least one of the first and second bead plates.
6. The metal gasket of claim 1 , wherein a gap filler is arranged on at least a portion of an outermost surface of at least one of the first and second bead plates at a location corresponding to the secondary bead so as to protrude from the outermost surface of the at least one of the first and second bead plates.
7. The metal gasket of claim 1 , wherein the plurality of exhaust cooling water holes have a different shape than the plurality of cooling water holes.
8. The metal gasket of claim 7 , further comprising a plurality of oil holes, wherein the plurality of oil holes have a different shape than the plurality of cooling water holes and the plurality of exhaust cooling water holes.
9. An engine including the metal gasket of claim 1 .
10. An outboard motor including the engine of claim 9 .