JP2004197799A - Metal gasket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal gasket enabling to adjust surface pressure loaded to a bead part without using a separate part. <P>SOLUTION: Thickness of coating material 18b applied on a front and a back surface of a bead plate 11 of "a" is thicker at a bore bead 13 formed around a bore 12 than thickness of coating material 18a applied on a front and back surface of an outer circumference half bead 15. Consequently, surface pressure acting on the outer circumference half bead 15 is released as surface pressure acting on the bore bead 13 increases, sealing performance at the bore part 12 having high inner pressure is improved. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a metal gasket used for a metal gasket that is inserted between a cylinder head and a cylinder block of an engine to perform sealing.
[0002]
[Prior art]
For example, a metal gasket is generally used as a sealing means used for sealing between a cylinder head and a cylinder block of an automobile engine. These metal gaskets have a single-layer structure using only one bead plate having a bead forming a seal portion, or a multi-layer structure obtained by combining this bead plate with another sub-plate (a folded plate, an adjustment plate, etc.). Various types such as those having a structure have been put to practical use.
[0003]
FIG. 5 shows a typical bead plate of these metal gaskets. Combustion chamber holes (bore holes) 12 are provided in the bead plate 11 of the metal gasket by the number of cylinders of the engine, and a bead 13 forming a seal portion is provided so as to surround the same. A plurality of bolt holes 14 for fixing the metal gasket between the cylinder head and the cylinder block are provided.
[0004]
In addition, the actual bead plate is provided with holes for passage of lubricating oil and cooling water, and a bead for sealing them is provided, which has a complicated shape. Is not shown. Reference numeral 15 denotes an example of an outer peripheral bead, which is a step-shaped bead called a half bead.
[0005]
The bead 13 is a portion formed by pressing a flat bead plate 11 to have a trapezoidal or substantially semicircular cross section. Similarly, the half bead 15 also has a step-shaped cross section. A metal gasket formed by only the bead plate 11 or a metal gasket formed by laminating the bead plate 11 and other sub-plates (turning plate, adjustment plate, etc.) is inserted between the cylinder head and the cylinder block and the bolt is inserted. When the bead 13 is tightened, the top portion and the lower end portion of the bead 13 are subjected to the pressure, and the portion between the top and the surface of the bead 13 is sealed. Is sealed with the member on the surface of Further, in the half bead 15, a seal is formed between each of the mating surface members at the front end and the rear end.
[0006]
In order to more reliably seal such a bead 13 or a half bead 15, a coating material is generally applied to each bead and a predetermined range on both sides thereof.
[0007]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-54740
[Problems to be solved by the invention]
In such a metal gasket, it is very important to adjust the surface pressure of the bead portion. In other words, the surface pressure is generated by sandwiching the metal gasket between the cylinder block and the cylinder head and tightening with bolts. However, if the surface pressure is too low, sufficient sealing performance is not exhibited, and if the surface pressure is too high, It causes settling of the bead, crushing of the coating material, and the like, and the sealing performance deteriorates as the operation time of the engine becomes longer.
[0009]
The optimum surface pressure varies depending on the place to be sealed. In other words, a high internal pressure acts on the bore of the engine, so a high surface pressure is required on the bead around the bore, but a high internal pressure does not act on the water hole and oil hole, The sealing can be sufficiently performed only by applying a low surface pressure to the formed bead portion.
[0010]
However, usually, in a gasket for a cylinder head, since a strong tightening force acts near the bolt tightening portion, the tightening force in the vicinity of a region connecting the bolt holes along the outer peripheral side of the engine increases, and the gasket for the bore side increases. The tightening force is lower than that. Therefore, it is often necessary to compensate for the surface pressure on the bore hole side.
[0011]
Conventionally, in order to satisfy such a demand, the surface pressure applied to the bead portion around the bore hole is reduced by, for example, sandwiching another member (a ring-shaped plate or the like) between the bead portion around the bore hole. A method has been taken to increase the surface pressure applied to the substrate. However, providing such a separate member increases the number of necessary parts, and in the case where a member such as a metal plate is sandwiched, fine adjustment cannot be performed because of the thickness limitation. Had the problem that
[0012]
Also, depending on the rigidity of the cylinder head and cylinder block, the difference in surface pressure between the two sides in the longitudinal direction and the center of the engine due to bending, and the difference in surface pressure between the vicinity of the bolted portion and the region apart from the bolted portion such as between bolts There is a problem that becomes large. As a method for solving this problem, for example, as described in Japanese Patent Application Laid-Open No. 2002-54740, a method is known in which the coating around the inner bore hole where the reduction in surface pressure due to deflection is greatest is thickened. . However, this method cannot be applied to an engine having two or less cylinders, and cannot improve the surface pressure difference in a region apart from the bolted portion, such as between the bolted portions.
[0013]
Further, some metal gaskets have an overhang portion (extending portion). This has a bead plate as shown in FIG. In this bead plate 11, an oil hole 16 is formed outside the bolt hole 14. Such a structure in which a part or all of the water hole or oil hole to be sealed protrudes outside the center of the bolt hole is referred to as overhang (extension). The overhang portion of the cylinder head is warped on the same principle as the deflection, and the interval between the cylinder head and the cylinder block is widened. There is a possibility that the pressure becomes low and sufficient sealing cannot be performed. In practice, the water hole and the water hole seal bead are provided on the outer periphery (inside of the overhanging oil hole) passing near the bolt hole, but are not shown in FIG.
[0014]
The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a metal gasket bead plate and a metal gasket that can adjust the surface pressure applied to the bead portion without using a separate member.
[0015]
[Means for Solving the Problems]
A first means for solving the above-mentioned problem is a metal gasket for a cylinder head composed of one metal bead plate, wherein the metal bead plate has fluid holes such as a combustion chamber, a water hole, and an oil hole of an engine. A bead that surrounds and seals them is formed, and an outer bead is formed around the outer periphery of the metal plate and collectively surrounds these fluid holes, and a predetermined portion including on each bead is formed. A metal gasket in which a coating material is applied to both surfaces of the metal plate, wherein the total film thickness of both surfaces of the coating material of the outer peripheral bead portion is the total film thickness of both surfaces of the coating material of the bead portion around the combustion chamber. And a metal gasket having a thickness substantially equal to the coating thickness of one layer on one side.
[0016]
In addition, this outer peripheral bead may be formed separately from each fluid hole, but in general, for a plurality of water holes, a water hole bead surrounding the water holes collectively is formed around the outer periphery of the gasket. Often formed to pass through.
[0017]
In this means, the total thickness of the coating material on both sides of the coating material on the outer peripheral bead portion is approximately the same as the coating thickness of one layer on one side of the total film thickness on both surfaces of the coating material on the bead portion around the combustion chamber. As a result, the distribution of the thickness of the gasket is in accordance with the deflection of the cylinder head. For this reason, the surface pressure around the bore can be improved, and excessive surface pressure concentration on the outer peripheral side can be suppressed, so that an appropriate surface pressure can be obtained. This means is applicable regardless of the number of cylinders of the engine. In addition, "substantially the same thickness" means that even if the thickness is not completely the same, it can provide both the proper sealing performance and the effect of absorbing the change in the space between the cylinder head and the cylinder block due to deflection. This means that a slight thickness deviation is allowed, and the limit is appropriately determined by the shapes of the cylinder head and cylinder block and the shape of the metal gasket.
[0018]
In this regard, in this sense, it is preferable that the total coating thickness on the outer periphery is set to be equal to one layer on one side of the coating around the combustion chamber, that is, equivalent to 50%, but may be slightly deviated from 50%. . Practically, if the total thickness of the outer periphery is 40 to 60% of the total thickness around the combustion chamber, a sufficient effect can be obtained.
[0019]
A second means for solving the above problem is a metal gasket for a cylinder head in which two or more metal plates are stacked in layers, and at least one metal plate (metal bead plate) is provided with an engine A bead that surrounds and surrounds each of the fluid holes such as the combustion chamber, the water hole, and the oil hole, and a bead that seals them is formed, and an outer peripheral bead that collectively surrounds each of these fluid holes passes near the outer periphery of the metal plate. A coating material is applied to at least one of the upper and lower surfaces of the metal gasket, the upper and lower surfaces of the metal gasket that are in contact with the cylinder head and the cylinder block, and the metal plate surface between the layers. The number of surfaces to which the coating material is applied is at least as large as the number of surfaces to which the coating material is applied in the outer peripheral bead portion. Surface is more, thereby, the total thickness of the coating material, the bead portion around the combustion chamber, it is metal gasket (claim 2), characterized in that is thicker than the outer peripheral bead portion.
[0020]
Also in this means, since the total thickness of the coating material is larger in the bead portion around the combustion chamber than in the outer peripheral bead portion, the distribution of the thickness of the gasket conforms to the deflection of the cylinder head. Therefore, the surface pressure around the bore can be improved, and the concentration of the surface pressure on the outer peripheral side can be suppressed. This means is applicable regardless of the number of cylinders of the engine.
[0021]
In the case of a laminated gasket, the difference in the number of coating surfaces between the periphery of the combustion chamber and the outer periphery may be one, but if the number of layers of the gasket increases, the level difference may also increase. Accordingly, the difference between the number of coated surfaces may be two or more.
[0022]
Furthermore, in this means, in the laminated gasket, the total thickness of the entire coating can be changed depending on the location depending on the presence or absence of the coating without changing the coating thickness within the same surface of each metal plate. The thickness can be adjusted very easily.
[0023]
A third means for solving the above-mentioned problem is the first means or the second means, wherein the metal gasket has an extending portion extending outward, and In the extension portion, in which an oil hole and an oil hole bead surrounding the oil hole are formed, the total thickness of the coating material in the oil hole bead portion is made larger than the total thickness of the coating material in the outer peripheral bead portion. (Claim 3).
[0024]
This means relates to a metal gasket having an extension (overhang). In such a metal gasket, as described above, an oil hole is provided in the extending portion, and the oil hole is outside the outer peripheral bead. In this means, as described above, even if the overhang portion warps and the interval between the cylinder head and the cylinder block is widened, the coating thickness of the oil hole bead portion provided in the overhang portion is increased. Since the thickness is larger than the coating thickness of the outer peripheral bead portion, the bead surface follows the spread, thereby preventing the surface pressure from becoming uneven.
[0025]
A fourth means for solving the above-mentioned problem is any one of the first means to the third means, wherein the total thickness of the coating material in the metal gasket is such that the combustion chamber of the engine, water holes, In the bead portion surrounding the fluid hole around the oil hole, the outer peripheral bead portion, and in the case of having the oil hole bead, in each bead portion of the oil hole bead portion, a portion near the bolt hole and a portion far from the bolt hole, respectively. (Claim 4).
[0026]
When the cylinder head and the cylinder block are tightened with bolts, as described above, the surface pressure is higher in a portion close to the bolt than in a portion far from the bolt hole. In this means, since the total thickness of the coating material is thinner in the portion close to the bolt hole than in the portion far from the bolt hole, the reduction of the surface pressure at a position away from the bolt, such as between bolts, is reduced. Can be suppressed, and the surface pressure can be made uniform.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a cross section of a bead portion of a bead plate which is an example of an embodiment of the present invention, and corresponds to an AA cross-sectional view of FIG. The structure of the bead plate according to the embodiment of the present invention is the same as that shown in FIGS. Therefore, in the following drawings, the same components as those shown in FIGS. 5 and 6 are denoted by the same reference numerals, and description thereof will be omitted. 5 and 6, the following FIGS. 1 to 4 show the concept of the configuration, and the dimensions shown in the drawings do not correspond to actual dimensions. Also, the dimensions between the drawings do not correspond.
[0028]
In the bead plate 11 of FIG. 1A, the thickness of the coating material 18 b applied to the front and back surfaces of the bore bead 13 formed around the bore hole 12 is equal to the thickness of the coating material 18 b applied to the front and back surfaces of the half bead 15. It is thicker than the thickness of the coating material 18a to be formed. As a result, the surface pressure concentrated on the outer peripheral portion due to the deflection of the cylinder head can be reduced, and the deformation due to the deflection can be absorbed in the outer peripheral portion. Therefore, the surface pressure applied to the bore milk bead 13 can be increased, and the bore having a high internal pressure can be obtained. The sealability can be improved and the outer peripheral surface pressure can be optimized at the holes 12.
[0029]
In the bead plate 11 of FIG. 1B, the coating material is applied twice on the front and back surfaces of the bead hole 13 formed around the bore hole 12 to 18b and 18c to form a two-layer structure. Has become. On the other hand, the coating material 18a applied to the front and back surfaces of the half bead 15 is a single layer. Even if the thickness of each coating film is the same, the thickness of the coating material in the bead for bore hole 13 is increased by the number of layers. Has become. Therefore, such a system also has the same operational effects as those shown in FIG.
[0030]
FIG. 2 is a diagram showing a portion corresponding to the AA cross-sectional view of FIG. 5 in a metal gasket using two bead plates 11 stacked on each other. In this case, the coating material 18b is applied to a total of four surfaces in 13 parts of the bead for the bore hole, but the coating material 18a is applied to only three surfaces in the 15 parts of the half bead. Therefore, the coating thickness as a whole is higher at the bead hole portion 13 than at the half bead 15 portion, and the surface pressure of the bore hole bead 13 can be increased.
[0031]
FIG. 2 shows a case where two bead plates 11 are used. However, even when the bead plate and another auxiliary plate are used in an overlapping manner, a coating corresponding to the bead of the other auxiliary plate is coated. Then, the surface pressure may be adjusted by adjusting the number of surfaces coated as the whole metal gasket. Similarly, in a metal gasket composed of three or more metal plates, the surface pressure can be adjusted by increasing the number of coating surfaces on the bore side than on the outer peripheral side.
[0032]
FIG. 3 is a diagram showing a cross-sectional view taken along line CC in FIG. In FIG. 3A, the coatings 19a and 19b of the oil hole seal bead 17 are applied so that the thickness of the coating 19a and 19b is thicker than the coating 18a of the outer peripheral half bead 15 part. Although the thickness of the coatings 19a and 19b can be sufficiently reduced even if the thickness is constant over the entire circumference of the oil hole seal bead 17 as shown in FIG. 3 (a), as shown in FIG. 19a on the side opposite to the hole 14 may be thick and 19b near the bolt hole 14 may be thin. In the case of a gasket in which two or more layers are laminated, as shown in FIG. 3 (c), the thickness may be adjusted according to the number of surfaces of the coat. By further changing the thickness according to the above, a further improvement in the sealing performance can be expected.
[0033]
Also in this case, the total thickness of the coating 18a on the outer peripheral bead 15 part should not be greater than the total thickness of the coatings 19a and 19b on the oil hole seal bead 17 part.
[0034]
FIG. 4 is a diagram showing an example of another embodiment of the present invention, and is a comparison between the AA cross section and the BB cross section in FIG. FIG. 4A is a sectional view taken along line AA, and FIG. 4B is a sectional view taken along line BB. Since the BB portion is closer to the bolt hole 14 than the AA portion, it is more likely to receive a greater surface pressure. Therefore, in the BB portion, as shown in FIG. 4B, the thickness of the coating material 18b is smaller than that in the AA portion shown in FIG. 4A. Thereby, the surface pressure applied to the AA portion and the surface pressure applied to the BB portion are made uniform.
[0035]
FIG. 4 shows an example in which the thickness of the coating material itself is changed. However, as in FIG. 1B, the number of layers of the coating material is changed, or two or more layers are laminated as shown in FIG. In the case of the metal gasket described above, the number of surfaces on which the coating material is applied may be changed. However, in any case, the total thickness of the coating 18a on the half bead 15 is set to be smaller than the total thickness of the coating 18b on the bore hole bead 13.
[0036]
Examples of the coating material include rubber-based coating agents such as fluorine-based rubber, NBR rubber, and silicon-based rubber, heat-resistant resin coating agents such as epoxy resin and phenol resin, and heat-resistant resins such as polyvinyl butyral and EVA copolymer. Various materials can be used, such as a coating agent added with a suitable thermoplastic resin, and a coating agent appropriately filled with a filler for improving a lubricating effect.
[0037]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a metal gasket bead plate and a metal gasket that can adjust the surface pressure applied to the bead portion without using a separate member. In particular, resin-based coating agents are less likely to be compressed than rubber-based coating agents, so that differences in coating thickness tend to be reflected in differences in thickness at the time of tightening, and the effects of the present invention can be more remarkably obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing a cross section of a bead portion of a bead plate which is an example of an embodiment of the present invention.
FIG. 2 is a diagram showing an example of a portion corresponding to a cross-sectional view taken along the line AA in FIG. 5 when the present invention is applied to a metal gasket using two bead plates 11 stacked on each other.
FIG. 3 is a view showing an example of a cross-sectional view taken along the line CC when the present invention is applied to the bead plate shown in FIG. 6;
4 is a diagram showing a comparison between examples of AA cross section and BB cross section when the present invention is applied to the bead plate shown in FIG. 5;
FIG. 5 is a view showing a typical bead plate of a metal gasket.
FIG. 6 is a diagram showing an example of a bead plate having an overhang portion.
[Explanation of symbols]
11: Bead plate 12: Bore hole 13: Bead (bead for bore hole)
14 ... Bolt hole 15 ... Half bead 16 ... Oil hole 17 ... Oil hole seal bead 18a-18c ... Coating material 19a-19b ... Coating material

Claims (4)

A cylinder head metal gasket comprising a single metal bead plate. The metal bead plate is formed with a bead that surrounds and seals around a fluid hole such as a combustion chamber, a water hole, and an oil hole of an engine. At the same time, an outer peripheral bead was formed to surround each of these fluid holes collectively around the outer periphery of the metal plate, and coating materials were applied to both surfaces of the metal plate at predetermined positions including on each bead. A metal gasket, wherein the total film thickness of both surfaces of the coating material of the outer peripheral bead portion is substantially equal to the coating thickness of one layer for one surface of the total film thickness of both surfaces of the coating material of the bead portion around the combustion chamber. Metal gasket characterized by its thickness. A metal gasket for a cylinder head in which two or more metal plates are stacked in layers, and at least one metal plate (metal bead plate) has around the fluid holes of the engine combustion chamber, water holes, and oil holes. A metal gasket, wherein a bead is formed around the metal plate, and a bead is formed around the metal plate so as to surround these fluid holes. The coating material is applied to at least one of the upper and lower surfaces respectively in contact with the cylinder head and the cylinder block, and the metal plate surface between the layers, and the number of surfaces where the coating material is applied in the bead portion around the combustion chamber is At least one surface is provided more than the number of surfaces on which the coating material is applied in the outer peripheral bead portion. Metal gasket total thickness, the bead portion around the combustion chamber, characterized in that it is thicker than the outer peripheral bead portion of. 3. The metal gasket according to claim 1, wherein the metal gasket has an extending portion extending outward, and an oil hole is formed in the extending portion of the metal bead plate and surrounds the oil hole. 4. A metal gasket in which an oil hole bead is formed, wherein the total thickness of the coating material in the oil hole bead portion is larger than the total thickness of the coating material in the outer peripheral bead portion. The metal gasket according to any one of claims 1 to 3, wherein a total thickness of the coating material in the metal gasket is around a fluid chamber of a combustion chamber, a water hole, and an oil hole of an engine. The surrounding bead portion, the outer peripheral bead portion, and in the case of having the oil hole bead, in each bead portion of the oil hole bead portion, a portion closer to the bolt hole is thinner than a portion far from the bolt hole. A metal gasket, characterized in that:

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