JP2007170461A - Metal gasket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal gasket having sufficiently improved sealing performance by giving a difference between the thicknesses of graphite sheets with embossing operation to ensure uniform bearing pressure required for sealing on a peripheral portion of an opening hole corresponding to a hole to be used. <P>SOLUTION: The metal gasket 1 is provided in a joint part between a cylinder head 20 and a cylinder block 10, when used. It also used for a joint part of an exhaust system manifold having great distortion on the engine side. It comprises the graphite sheets 3, 3 mounted on both side faces of a metal thin plate 2. The at least graphite sheet 3 on the single side face is embossed and molded to be compressed in at least outward part to maximize a thickness T1 of the peripheral portion 5 of the opening hole 1a corresponding to a bore hole or a fluid distribution hole so that a thickness T2 of an embossed part 7 is smaller than the thickness T1 of the peripheral portion 5 of the opening hole. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a metal gasket that is used mainly in a joint portion that requires sealing performance, such as a joint portion between a cylinder head and a cylinder block of an engine.

  For example, as a gasket to be used by interposing between a cylinder head and a cylinder block of an engine, a base material is a thin metal plate such as stainless steel having elasticity, and at least a joint surface of the cylinder head or cylinder block or the like. A so-called metal gasket is known in which a sealing material layer such as a rubber film for ensuring a sealing function is provided on the contact surface side. This metal gasket is provided with an opening corresponding to a bore hole serving as a combustion chamber in the cylinder block or cylinder head, and an opening corresponding to a bolt hole for tightening. A liquid circulation hole such as a liquid circulation hole or an oil hole for lubricating oil is provided.

  The metal gasket may be a single metal sheet as a base material, but is usually used by laminating a plurality of the metal sheets. The metal gasket has a folded back edge, a cross-sectional mountain shape, and a stepped shape in order to ensure a surface pressure for sealing at a necessary portion such as a peripheral portion of the opening corresponding to the bore hole. Sealing means such as a bead or shim member is provided.

  For example, as shown in FIG. 9, the metal thin plate serving as the base material has a two-layer laminated structure, and a bead 106 a having a mountain shape or a step shape is formed in the opening peripheral portion 105 of both the metal thin plates 102 and 102, There is known a so-called medium shim type sealing means in which a plate-like shim member 109 is inserted between the two thin metal plates 102 and 102 to ensure a surface pressure necessary for sealing the peripheral portion 105 of the hole. In addition, as disclosed in Patent Document 1 below, there is also known a structure in which a shim member is sandwiched between folded portions of a thin metal plate so that the thickness is maintained and a surface pressure for sealing is ensured. Furthermore, a so-called welding type sealing means is also known, in which a metal auxiliary plate is welded to the outer surface of a thin metal plate serving as a base material to provide a level difference to ensure a surface pressure necessary for sealing.

  However, in any of the above cases, since a step is provided by a metal plate such as a shim member in the periphery of the opening, the surface pressure distribution due to tightening cannot be adjusted, and the surface in the periphery of the bore hole There was a risk of non-uniformity in the pressure and adverse effects such as deformation of the bore hole shape. Further, the thickness of the metal thin plate and shim member used is limited due to workability and market distribution due to the lamination of the metal thin plates and the insertion of shim members.

  The rubber gasket or the synthetic resin coating layer as the sealing material layer in the metal gasket may not be able to perform the initial sealing function due to thermal deterioration due to use under high temperature conditions. In addition, a metal gasket using a graphite sheet that has excellent heat resistance and chemical stability, excellent compressibility, resilience, stress relaxation, flexibility, etc. has been proposed in place of the coating film layer of synthetic resin ( For example, the following patent documents 2-4).

  However, in the case of a conventional metal gasket using a graphite sheet, a certain degree of sealing performance can be maintained due to the compressibility of the graphite sheet, but the thickness and density are almost constant as a whole, so load distribution by tightening varies. Therefore, it is difficult to adjust the surface pressure distribution, and there is a risk of adversely affecting the uniformity of the surface pressure in the peripheral portion of the opening corresponding to the peripheral portion of the bore hole, and the shape and sealability of the bore hole. Therefore, even in the case of using a graphite sheet, the surface pressure is secured by inserting a shim member in addition to the bead.

  The graphite sheet is weaker in bonding strength with the metal thin plate than the coating film layer. For example, as shown in FIG. 9, it is used for liquid circulation such as a cooling liquid circulation hole or an oil hole as a water jacket. In the case where the hole 113 is open to the joint surface of the cylinder block 110 and the gasket made of the graphite sheet is used at the joint between the cylinder block 110 and the cylinder head 120, the liquid circulation hole 113 is formed in the hole 113. The exposed graphite sheet may be weakened by contact with liquids such as water and oil, and peeling may occur.

Further, in the case of an exhaust system manifold gasket used for sealing a joint part in an exhaust path such as a joint part between an exhaust system manifold and a cylinder head, the peripheral part of the opening corresponding to the fluid circulation hole such as the exhaust gas is also used. It is difficult to adjust the surface pressure distribution with respect to tightening, and there is a possibility of adversely affecting the sealing performance and the shape of the circulation hole in the periphery of the circulation hole.
JP-A-11-159623 Japanese Utility Model Publication No. 4-1779 Japanese Patent Laid-Open No. 6-81961 JP-A-6-147326

  The present invention has been made in view of the above, and as a metal gasket to be used for a joint that requires a cylinder head gasket, an exhaust system manifold gasket or other seals, heat resistance as a sealing material layer on both sides of a thin metal plate. And a surface necessary for sealing in the peripheral portion of the opening corresponding to the hole of the product to be used by making a difference in the thickness of the graphite sheet by embossing compression, in which a graphite sheet having good compressibility is installed. The surface pressure of the peripheral part of the hole and the entire gasket is made uniform so that the pressure can be secured, and the metal thin plate is made up of one layer by making the surface pressure uniform and changing the load distribution. However, it is an object of the present invention to provide a low-cost metal gasket that can exhibit sufficient and good sealing properties and the effect of reducing deformation of the hole shape.

  The metal gasket of the present invention that solves the above problems is a metal gasket having openings corresponding to the holes of a product to be used and having graphite sheets installed on both sides of a thin metal plate as a substrate. The graphite sheet on at least one side surface is compressed by embossing at least a part of the outer periphery from the periphery of the opening so that the thickness of the periphery of the opening becomes the maximum thickness. The thickness is made thinner than the peripheral portion of the opening.

According to this metal gasket, retaining the thickness of the periphery of the opening with the graphite sheet increases the tightening load at the periphery of the opening, ensuring sufficient surface pressure necessary for sealing and improving the sealing performance. To do. Moreover, since the above-mentioned thickness retention is due to the graphite sheet, the surface pressure around the aperture is equalized by the compressibility of the graphite sheet. In particular, by arbitrarily setting the embossing range, shape, embossing step amount, etc., the tightening load distribution can be adjusted easily and as planned. Can be easily obtained, and further, the sealing performance can be ensured without increasing the surface pressure so much, so that the effect of suppressing deformation of the hole shape can also be enhanced. Further, the portion of the graphite sheet that has been pressed and compressed is increased in density to improve sheet strength, and peeling and the like are less likely to occur.
Therefore, it is a metal gasket that is used at the joint between the cylinder head and cylinder block of the engine. The opening corresponds to the bore hole of the engine, and the periphery of the opening corresponds to the periphery of the bore hole. In the case of what is to be done, it is possible to equalize the surface pressure at the peripheral portion of the bore hole and the like, and to enhance the sealing performance of the portion and the effect of preventing deformation of the bore hole shape.

  Further, in the case of a metal gasket used for a joint part in an exhaust system manifold, the opening corresponds to a flow hole for fluid such as exhaust gas, and the peripheral part of the opening corresponds to the peripheral part of the flow hole. In addition, since the surface pressure around the circulation hole can be equalized, it is possible to enhance the sealing performance and the effect of preventing deformation of the circulation hole shape.

  In the metal gasket, it is preferable that the graphite sheet is compressed by embossing so as to surround the periphery of the opening in the outer portion of the periphery of the opening. A sufficient surface pressure for sealing can be secured in the entire periphery of the opening corresponding to the hole or the like.

  Further, in the metal gasket, when the portion of the graphite sheet exposed to the hole for liquid circulation such as water or oil is compressed by embossing, the portion exposed to the hole is thickened by embossing. Since the thickness of the sheet is reduced and the density is increased, the strength of the graphite sheet at this portion is increased, the bonding property to the metal thin plate is good, and peeling does not occur even when contacted with liquid such as water or oil. .

  Furthermore, it is preferable that a bead is provided in the peripheral portion of the opening, and a portion of the graphite sheet in the outer portion including the bead is embossed. In this case, the shape of the bead and the thickness retention by the graphite sheet combine to increase the tightening load at the bead portion and to realize high compression, and to open the holes corresponding to the bore holes and the flow holes. The sealing performance at the periphery of the hole is further enhanced.

  Further, the graphite sheet may be compressed by embossing at the outer part from the peripheral part of the opening except for the outer peripheral part of the gasket. In addition, it is possible to adjust the load distribution by tightening by embossing an arbitrary local part, to ensure local surface pressure unique to the engine and to reduce deformation of the bore hole shape.

  As described above, according to the metal gasket of the present invention, the graphite sheet as the sealing material layer is installed on both side surfaces of the metal thin plate, and the portion of the graphite sheet outside from the periphery of the opening is compressed by stamping. By reducing the thickness and maximizing the thickness of the periphery of the aperture, the surface pressure required for sealing is secured in the periphery of the aperture without stacking other members such as shim members. It is possible to improve the sealing performance of the peripheral portion of the opening, reduce the deformation of the hole shape of the product to be used such as the shape of the bore hole, and the metal thin plate as the base material is composed of one layer. The gasket as a whole can exhibit good sealing properties. Moreover, it is only necessary to compress the graphite sheet by embossing, and unlike the case of laminating other members, it is easy to manufacture and can be provided at low cost.

  Therefore, the metal gasket of the present invention can be used well in joints that require a cylinder head gasket or an exhaust system manifold gasket or other seals.

  Next, embodiments of the present invention will be described based on examples shown in the drawings.

  1 is a schematic plan view illustrating a metal gasket according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of the same part, and FIGS. 3 to 5 are partial enlarged cross-sectional views showing other embodiments, respectively. is there.

  In the figure, reference numeral 1 denotes a metal gasket as a cylinder head gasket used mainly at a joint between a cylinder block 10 and a cylinder head 20 of a multi-cylinder engine, and is formed by using a metal thin plate 2 having elasticity such as stainless steel as a base material. Has been. As shown in the figure, the metal gasket 1 has an opening 1a corresponding to a bore hole 11 provided in a cylinder block 10 which is a product to be used and an opening 2a corresponding to a bolt hole for tightening.

  In the case of the illustrated embodiment, as illustrated in FIG. 2, a cooling liquid circulation hole 13 as a water jacket surrounding the outside of the bore hole 11 in the cylinder block 10 is joined to the cylinder head 20. In a so-called open deck type engine that is open to the surface, a case is shown in which the cylinder block 10 and the cylinder head 20 are used at the joint. Although not shown, it is needless to say that the gasket of the present invention can be used in a closed deck type engine.

  A peripheral portion 5 of the opening 1a corresponding to the peripheral portion of the bore hole 11 of the metal gasket 1 has a bead for securing a surface pressure at the time of tightening, for example, a mountain shape as shown in FIGS. A bead 6 a (full bead) or a stepped bead 6 b (half bead) as shown in FIGS. 4 and 5 is formed so as to surround the opening 1 a corresponding to the bore hole 11. Of course, a bead similar to the above can also be formed in the periphery of the gasket outer peripheral portion 4 and a hole for liquid circulation such as water or oil (for example, the circulation hole 13). Reference numeral 6 c denotes a step-shaped bead on the outer peripheral portion 4.

  And the metal gasket 1 of this invention is equipped with the graphite sheet (graphite sheets) 3 and 3 as a sealing material layer in the both sides | surfaces of the said metal thin plate 2, as shown in FIGS. In particular, at least the graphite sheet 3 on one side, preferably the graphite sheets 3 and 3 on both sides, at least in the outer part of the peripheral part 5 of the hole so that the thickness T1 of the peripheral part 5 is maximum. A part is compressed by stamping, and the thickness T2 of the stamped portion 7 is made thinner than the thickness T1 of the peripheral portion 5 of the opening.

  Regarding the form and range of embossing of the graphite sheet 3, at least in the peripheral portion 5 surrounding the opening 1a corresponding to the bore hole 11, particularly in the region of the opening peripheral portion 5 including the bead 6a or 6b. As long as the original thickness of the graphite sheet 3 on at least one side is left as it is, implementation in various embossed forms is possible.

  For example, in the embodiment shown in FIGS. 1 and 2, the graphite sheets 3 and 3 on both sides are located outward from the perforated peripheral portion 5 so as to surround the perforated peripheral portion 5 where the mountain-shaped beads 6a are formed. The case where the whole part is stamped and molded in the same manner is shown. In the embodiment shown in FIG. 3, the outer peripheral portion 4 where the beads 6c are formed also has an original thickness at least on one side (both sides in the drawing) of the graphite sheet 3 as in the peripheral portion 5 of the opening. A case is shown in which the other part of the outer part is stamped and molded as it is.

  In the embodiment of FIG. 4, in which the stepped bead 6 b is formed in the peripheral portion 5 of the aperture, the original thickness of the graphite peripheral portions 3, 3 on both sides is kept as it is in the peripheral portion 5 of the aperture. A case where the entire outer portion is stamped in the same manner so as to remain is shown. The outer peripheral portion 4 of this embodiment can also be embossed so as to leave at least the original thickness of the graphite sheet 3 on one side as shown by the chain line in FIG.

  In any of the above cases, the graphite sheets 3 and 3 on both sides have been shown to be stamped together so as to retain the original thickness in the peripheral portion 5 of the opening. As shown in FIG. 5, only one of the graphite sheets 3 and 3 on both sides can be stamped.

  In addition, in other parts such as the hole for liquid circulation such as water and oil and around the bolt hole, the mold is removed except for the part so as to retain the original thickness of the graphite sheet according to the necessity. It can also be extruded. Furthermore, depending on the required surface pressure during tightening, the thickness of the metal gasket can be changed stepwise depending on whether there is a partial difference in the degree of embossing or the presence or absence of embossing of the graphite sheets 3 and 3 on both sides. It is also possible to make it.

  In any of the above embodiments, as shown in FIG. 2, a hole for liquid circulation such as water or oil, for example, the portion of the graphite sheet 3 exposed in the circulation hole 13 is stamped and compressed. It is good. That is, the portion of the graphite sheet 3 exposed in the flow hole 13 is embossed and densified to increase the strength of the graphite sheet 3 and cause peeling even when contacted with liquids such as water and oil. And durability can be improved. In this case, the boundary between the non-embossed portion such as the peripheral portion 5 of the aperture and the embossed portion 7 does not necessarily coincide with the aperture end of the flow hole portion 13, as shown in FIG. In addition, by stopping the non-embossed portion up to the flow hole portion 13, an arbitrary surface pressure can be stably obtained regardless of processing variations on the engine side.

  The inner peripheral edge of the opening 1a corresponding to the bore hole 11 is attached with an annular reinforcing member 8 having a U-shaped cross section as shown in FIG. 6, and the graphite sheet 3 is peeled off from the end. It can also be implemented in such a way as to prevent.

  The stamping of the graphite sheet 3 is performed in the state of the sheet after the graphite sheets 3 and 3 are laminated and installed on the thin metal plate 2, or at the time of bead processing or trimming by press molding of the sheet. A necessary portion of the graphite sheet 3 is pressed and compressed, and the thickness thereof is reduced to make a difference between the thickness T1 of the peripheral portion 5 of the bore hole and the thickness T2 of the stamped portion 7. The difference between the thicknesses T1 and T2 (the level difference due to embossing) can be appropriately set depending on the original thickness of the graphite sheet 3 and the degree of embossing.

  Further, by arbitrarily setting the embossing range, shape, embossing step amount and the like of the graphite sheet 3, the tightening load distribution can be easily adjusted and set as planned, and thus corresponds to the opening. A surface pressure adapted to the hole shape such as a bore hole or a fluid circulation hole can be easily obtained. Therefore, the necessary sealing performance can be ensured with a relatively low surface pressure, so that the effect of suppressing deformation of the bore hole shape can be obtained.

  In each of the above embodiments, as the metal thin plate 2, a stainless steel plate having elasticity such as SUS301H is preferably used. The thickness is, for example, 0.1 to 0.5 mm, and more preferably 0.1 to 0.3 mm.

  The graphite sheet 3 is a sheet of layered graphite. For example, the graphite sheet 3 is a sheet of so-called expanded graphite obtained by treating graphite with an oxidizing agent and further rapidly heating it. In addition to chemical stability, it is excellent in compressibility, resilience, stress relaxation, flexibility and the like. Of course, graphite sheets obtained by methods other than those described above can be used, but those made of expanded graphite are particularly preferred from the viewpoint of the above characteristics and effects.

  Regardless of which graphite sheet is used, it is also possible to apply a low friction silicon-based coating agent or printing agent to the surface of the graphite sheet. Adhesion, peeling of the graphite sheet and collapsing can be prevented, and the durability can be further enhanced by fine adjustment of the surface pressure.

  The thickness of the graphite sheet is usually in the range of 0.05 to 0.5 mm, more preferably in the range of 0.05 to 0.2 mm, from the viewpoint of compressibility, sealing properties, cost, and the like. The thickness of the graphite sheet at the embossed portion can be set as appropriate depending on the degree of compression by the embossing, but it is usually set within the range of 0.03 to 0.1 mm because of the difference in thickness. Is particularly preferable.

  According to the metal gasket 1 of the present invention configured as described above, the graphite sheet 3 is provided on both surfaces that are in contact with the member to be joined when the metal gasket 1 is interposed between the cylinder block 10 and the cylinder head 20. , 3 is provided, the graphite sheet 3 can absorb the surface roughness of the joint surface between the block 10 and the head 20 to exhibit a good sealing function, and because of its heat resistance, the block 10 In addition, it can withstand high heat transmitted from the head 20 and hardly undergoes thermal deterioration.

  In particular, in the case of the present invention, the opening corresponding to the peripheral portion of the bore hole 11 is set by increasing the thickness of the peripheral portion 5 by pressing and compressing the outer portion of the peripheral portion 5. The tightening load at the hole peripheral portion 5 is increased, and particularly, the bead 6a or 6b provided in the portion becomes a high load, and compression due to the tightening of the bead portion is increased. Sufficient surface pressure required for sealing can be secured, and gas sealing performance is improved.

In addition, since the portion having the thickness is made of the graphite sheet 3, the compressibility of the graphite sheet 3 equalizes the surface pressure around the opening 1a, that is, the bore hole 11 corresponding to the opening 1a. The deformation of the hole shape can be reduced. Further, the portion of the graphite sheet that has been pressed and compressed is increased in density to improve sheet strength, and peeling and the like are less likely to occur.
Further, since it is only necessary to install graphite sheets 3 and 3 on both side surfaces of the single metal sheet 2 and press-mold at least the graphite sheet 3 on one side surface, the manufacturing process is easy and the cost is reduced. It can be obtained inexpensively.

  In the above-described embodiments, the metal gasket used as the cylinder head gasket has been described as an example. However, the present invention is also implemented by configuring the exhaust manifold gasket and other gaskets having a large engine side distortion in the same manner as described above. be able to.

  7 and 8 show an embodiment of the metal gasket 1 as a manifold gasket used for a joint portion of the exhaust path such as a joint portion between the exhaust manifold and the cylinder head, as in the case of the above-described embodiment. A thin metal plate 2 having elasticity such as stainless steel is used as a base material, and graphite sheets 3 and 3 are installed on both sides of the thin metal plate 2 as sealing material layers, and the manifold is a product to be used. An opening 1a ′ corresponding to a flow hole for fluid such as exhaust gas and an opening 2a corresponding to a bolt hole for tightening are provided. Further, a mountain-shaped bead or a step-shaped bead 6b is formed in the peripheral portion 5 surrounding the opening 1a 'as required.

  In this metal gasket 1, at least one side of the graphite sheet 3, preferably both sides of the graphite sheet 3, 3, at least a part of the outer part from the hole peripheral part 5 is compressed by stamping. Thus, the thickness T2 of the embossed portion 7 is formed thinner than the thickness T1 of the peripheral portion 5 of the opening.

  Also in this embodiment, the degree of compression of the graphite sheet 3 by the above-described stamping, the stamping range, the shape, and the like are appropriately determined according to the use mode and the like in the same manner as in the above-described cylinder head gasket. In the same manner as described above, the surface pressure of the peripheral portion 5 of the opening corresponding to the peripheral portion of the fluid circulation hole can be equalized, thereby improving the sealing performance and the effect of preventing deformation of the circulation hole shape. The effects similar to the above can be obtained.

  The metal gasket of the present invention can be suitably used as a cylinder head gasket that is used in a joint portion between an engine cylinder head and a cylinder block, and a joint portion of an exhaust path such as a joint portion between an exhaust system manifold and a cylinder head. It can be suitably used for so-called exhaust system manifold gaskets used in the above.

1 is a schematic plan view illustrating a metal gasket according to an embodiment of the present invention. It is a partial expanded sectional view same as the above. It is a partial expanded sectional view which shows another Example. It is a partial expanded sectional view which shows other Example. It is a partial expanded sectional view which shows other Example. It is a partial expanded sectional view which shows other Example. FIG. 6 is a schematic plan view illustrating a metal gasket according to another embodiment of the invention. It is an expanded sectional view of a VIII-VIII line same as the above. It is a partial sectional view which illustrates the conventional gasket.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal gasket 1a, 1a 'Opening hole 2 Metal thin plate 2a Opening hole 3 Graphite sheet 4 Outer peripheral part 5 Opening peripheral part 6a Mountain-shaped bead 6b Step-shaped bead 6c Outer peripheral part bead 7 Embossed part 11 Bore hole 13 Distribution Hole

Claims (7)

A metal gasket having openings corresponding to the holes of the product to be used, and having graphite sheets installed on both sides of a thin metal plate as a base material,
At least one part of the graphite sheet on at least one side surface is compressed by embossing so that the thickness of the peripheral portion of the opening becomes the maximum thickness, and the thickness of the embossed portion is compressed. Is made thinner than the peripheral portion of the opening.   It is a metal gasket that is used at the joint between the cylinder head and cylinder block of the engine, wherein the opening corresponds to the bore hole of the engine, and the periphery of the opening corresponds to the periphery of the bore hole The metal gasket according to claim 1.   The metal gasket used for the joint part in the exhaust manifold, wherein the opening corresponds to a flow hole for a fluid such as exhaust gas, and the peripheral part of the opening corresponds to a peripheral part of the flow hole. Metal gasket as described.   The metal gasket according to any one of claims 1 to 3, wherein the graphite sheet is compressed by embossing so as to surround the periphery of the opening at an outer portion of the periphery of the opening.   The metal gasket according to claim 2, wherein a portion of the graphite sheet exposed to a hole for flowing liquid such as water or oil outside from the periphery of the opening is compressed by embossing.   The metal according to any one of claims 1 to 3, wherein a bead is provided in the periphery of the opening, and a portion of the graphite sheet in an outer portion including the bead is embossed. gasket. The metal gasket according to any one of claims 1 to 3, wherein the graphite sheet is embossed at the outer portion from the periphery of the opening except for the outer periphery of the gasket.

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