Nippon Gasket Company, Ltd.

Other

Shigeru Kawaguchi

Kunitoshi Inoue

Kenji Kubouchi

Hiroshi Uemura

Masahiko Miura

Naoki Ii

Hideo Yamamoto

Kazuhiro Nomoto

Jin Hashioka

Ken Ohkura

Takeshi Kitamura

Tadaumi Matsumoto

A laminate-type metallic gasket comprising adjacent combustion chamber holes (A, A), a pair of bead substrates (,) made of an elastic metallic plate with a bead (,) formed along each of the combustion chamber holes (A, A) and first and second intermediate plates (,), in which peak portions of beads (,) are symmetrically opposite to each other, disposed between the two bead substrates (,) according to the present invention wherein a first intermediate plate (,) is provided with a step (,) having a thickness less than that of a second intermediate (,) formed along an edge portion (,) of the combustion chamber holes (A, A). The intermediate plate (,) is disposed upon an outer surface which is made of a downwardly convex surface (,) by a formation of the step (,), and an edge portion (,) of the second intermediate plate (,) being folded back between the second intermediate plate (,) and the edge portion (,) of the combustion chamber holes (A, A) of the first intermediate plate (,) to form the compensating portion (,) having a thickness larger than the total thickness of the two intermediate plates (,) at a portion, where peak portions of the beads (,) are respectively brought into contact with the first and second intermediate plates (,), around the combustion chamber holes (A, A).

Metallic gasket

The metallic gasket consists of a first elastic metallic plate having beads and folded portions and a second elastic metallic plate having beads, laminated on each other. The folded portions are formed by bending the plate alone the circumferences of cylinder bore holes, and the beads are formed on the portions of the plate spaced from the circumferences of the cylinder bore holes at a predetermined distance in the radially outward direction thereof, whereby double annular seal portions are formed. The projecting portions of the beads on the second elastic metallic plate are fitted in or brought into contact with the recessed portions or projecting portions of the beads on the first elastic metallic plate. The spring constant of the gasket becomes equal to the sum of those of the two plates, and this enables the stress carried by the plates to be lessened, and the durability of the gasket to be improved. It is also possible to reduce the width of the parts of the beads which are between the cylinder bore holes and use such a gasket suitably for an engine in which the distance between cylinder bores is small.

At the portions of the metallic gasket according to the present invention which are around perforations the inner diameter of which is smaller than that of holes for combustion chamber, the thickness of at least the folded portions and the portions of an elastic metallic plate on which these folded portions are laminated are reduced to a level in the range from a level not higher than that of the thickness of said metallic plate to a level not lower than that of a half of the thickness of said metallic plate. These thickness-reduced portions of the metallic plate are bent onto the bead-ridge-carrying side thereof to form folded portions, whereby the thickness of the folded portions is reduced to provide a difference in height between the folded portions and the bead-surrounding portions of the metallic plate. The metallic plate is heat treated after the folding step has been completed, to regulate the hardness of the metallic plate.

Metallic gasket and method of manufacturing the same

This invention provides a metal gasket and its production method which prevents damage to folded portions by fold-machining and damage to metal materials after fastening, and expands the range of selection of materials for elastic metal plates, by reducing the thickness of a predetermined region of a elastic metal plate at which folded portions are to be formed. The thickness of the folded portion of the elastic metal plate is reduced from the folding side in an inner region of folded base portions and in regions in which folded free ends are positioned. Bend-machining is made gently at the folded base portions subjected to fold-bend machining, and the folded base portions each have a gap there-inside. The folded free ends do not come into contact with the elastic metal plate due to recessed surfaces. Accordingly, cracks and wrinkles do not occur at the folded base portions, and the folded free ends do not leave friction traces on the elastic metal plate.

Metal gasket and production method thereof

In the metallic gasket according to the present invention, beads are formed on the circumferential portions of the first cylinder bore-aligned holes in the base member, and folded portions are formed on the auxiliary member by merely folding back the inner edge sections of the second cylinder bore-aligned holes therein so as not to embrace the bead-carrying base member, the auxiliary member being laminated on the side of the base member from which the beads project. In this metallic gasket, the folded portions of the auxiliary member restrict the deformation of the beads to minimize the occurrence of fatigue and cracks in the beads, whereby the sealing function of the gasket is improved with uniform and proper surface pressure distribution maintained. Soft members are provided between the main portion of the auxiliary member and the folded portions thereof so as to secure proper surface pressure distribution in the metallic gasket in accordance with the rigidity of the cylinder head.

This metal gasket interposes a regulation plate having compression stop portions and beads between first and second elastic metal plates the convexities of beads of which face one another. The compression stop portions prevent complete compression of each bead and absorbs any irregularity between opposed fitting surfaces around holes for a combustion chamber. An intermediate plate having an offset portion is sandwiched between the regulation plate and the second elastic metal plate. The offset portion is shaped to a height smaller than the thickness of the compression stop portions and regulates the degree of compression of each bead.

Metal gasket

Disclosed is a metal gasket for a manifold produced by laminating a plurality of bead plates having bead portions which are bent at a predetermined radius of curvature R and by setting the ratio R/t of the radius of curvature R to the thickness t of the bead plates to the range of 7 to 15. Therefore, the radius of curvature of the bent portions of the bead plates to the thickness can be made relatively great and the bent portions of the bead plates become smooth. As a result, when the metal gasket is tightened between a cylinder head and an exhaust manifold, the contact portions of the bead plates are expanded and the stress and face-to-face pressure occurring at the contact portions can be reduced. Accordingly, the stress acting on the bead plates can be made lower than a reference value, the increase of the facet-face pressure can be restricted to within a predetermined range and the stress and face-to-face pressure of the bead portions forming a seal surface can be kept within suitable ranges. For these reasons, even if great thermal deformation occurs in the exhaust manifold relative to the cylinder head, seal performance of the metal gasket is not lowered.

Metal gasket for manifold

This invention discloses the method of manufacturing metallic gaskets which are properly prestressed by a load which is determined according to a stress calculation. In the process of applying prestresses to the gaskets, a die formed to a thickness smaller than the thickness of the metallic gasket material--which has a bead portion and is coated with resin such as a fluoroelastomer--is placed close to and surrounding the outer circumference of the metallic gasket material or inside the holes formed in the metallic gasket material. Then, the tension side of the bead portion of the metallic gasket material is prestressed by a stress greater than a specified stress that will occur when the metallic gasket is used.

Growing community of inventors

Daitou, Japan

Shigeru Kawaguchi