JP2844500B2 - Metal gasket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal gasket used in a multi-cylinder internal combustion engine to seal a space between opposed mounting surfaces of a cylinder head and a cylinder block.

[0002]

2. Description of the Related Art Conventionally, a metal gasket made of a metal material has been used to seal between opposed mounting surfaces of a structural member of an internal combustion engine such as between a cylinder head and a cylinder block. The metal gasket has a bead near the periphery of the through hole corresponding to the cylinder bore, water and oil passages, and when the cylinder head and cylinder block are tightened and fixed with bolts etc. The bead forms an elastic annular contact portion to seal between the opposed mounting surfaces.

[0003] However, recent internal combustion engines are required to have a high output and a light weight.
There is a tendency to manufacture with an aluminum material having a small specific gravity instead of a casting. Aluminum materials are lightweight, but have low rigidity, so that the relative displacement of the cylinder head with respect to the cylinder block during operation of the internal combustion engine tends to increase.
When tightening the opposing mounting surfaces between these structural materials with tightening bolts via a single-plate metal gasket, the tightening bolt positions are dispersed on the outer peripheral portion or relatively outer peripheral portion of the metal gasket. Since the cylinder bores are not always evenly distributed around the periphery, the facing mounting surface is likely to be irregular. As a result, high-temperature and high-pressure combustion gas intrudes between the opposed mounting surfaces at locations where distortion is large, such as a portion between the cylinder bores, and corrodes the bead portion of the metal gasket interposed between the opposed mounting surfaces.
Soil and reduce the sealing effect.

Further, in the case of a cylinder head gasket, the distance between the cylinder head and the cylinder block repeatedly increases and decreases during the combustion cycle of the internal combustion engine, and the metal gasket is subjected to repeated stress, that is, mechanical stress and thermal stress. . This load fluctuation stress occurs as a large value at the lowest rigidity of the cylinder block or the cylinder head, and as a result, there is a problem that the bead is set or a crack is generated to deteriorate the sealing performance.

In view of the problems of the prior art, the present applicant has developed a metal gasket shown in FIGS. 16 and 17, and has previously filed an application as Japanese Patent Application No. 2-306295. The metal gasket 20 includes beads 24A and 24B formed along the cylinder bore holes 22A and 22B at radially outer sides from the periphery of the cylinder bore holes 22A and 22B formed in the elastic metal plate 21; 22
A metal gasket 20 which has folded portions 25A and 25B formed by being folded outward in the radial direction around A and 22B, and wherein the folded portions 25A and 25B of the elastic metal plate 21 are formed into a predetermined thickness and heat-treated. Has been proposed. Further, the metal gasket 20 has a bead 24A,
A metal plate 26 for thickness adjustment is laminated on the outer side in the radial direction of 24B and on the convex side of the beads 24A, 24B, and the metal plates 27A, 27B are interposed between the folded portions 25A, 25B.

Further, as shown in FIG. 18 and FIG. 19, the present applicant has developed a metal gasket and
No. 56189. The metal gasket 30
Are the beads 34A and 34B and the cylinder bore holes 3
In order to adjust the strength of the elastic metal plate 31 having the folded portions 35A and 35B formed by being bent outward in the radial direction around the circumferences 2A and 32B, the adjusting plate 36 is connected to the beads 34A and 3A.
4B and the beads 34A, 34B.
Extending in the radially outer region of Further, the metal gasket 30 is provided with a soft member 37 at the folded portions 35A and 35B.
A, 37B.

[0007]

However, the above-mentioned metal gasket proposed by the present applicant still has the following technical unsolved problems. That is, the metal gasket 20 is used to adjust the thickness of the bead 2.
Even if the metal plates 26 are stacked on the convex surfaces of the 4A and 24B, the stacking position is on the radial outside of the bead and does not include the position where the bead is formed. Therefore, the metal gasket 20 is basically formed of one elastic metal plate at the bead forming position, and when the metal gasket 20 is clamped between the opposed mounting surfaces, the load stress at the bead position is large. This results in full compression of the bead and exposure to severe conditions for durability.

Further, the metal gasket 30 is provided with a bead 34 for adjusting the strength of the elastic metal plate 31.
A and 34B and the radially outer region thereof are laminated and extended, but the laminated side of the adjusting plate 36 is the beads 34A and 34B.
B is a convex side, and the lamination range is a bead and a radially outer region thereof, and is not a layer that is laminated to the radially inner side of the beads 34A and 34B. Therefore, when the metal gasket 30 is clamped between the opposed mounting surfaces and tightened, a necessary step is obtained between the folded portions 35A, 35B and the radially outer regions of the cylinder bore holes 32A, 32B beyond the bead. On the other hand, not only the thickness of the elastic metal plate 31, the height of the beads 34A and 34B and the thickness of the folded portions 35A and 35B, but also
The thickness control of determining the step in consideration of the thickness of the adjustment plate 36 is very troublesome, and the folded portions 35A and 35B are not required.
In addition to the need to obtain the necessary steps only by the formation of the ridges, the load stress at the bead position is reduced, and the entire compression of the bead portion is avoided, which is not sufficient in terms of durability.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem, and to secure a double seal line between a bead portion and a folded portion around a cylinder bore hole, and to form a spring having two bead portions. Are arranged in series, even if irregularities occur in the opposed mounting surfaces of the two structural parts at the time of tightening, the bead or the folded portion is deformed in response to the distortion, making it easier to absorb the irregularities. Even during use after tightening is completed, the variable load due to the repetition of the combustion cycle of the internal combustion engine is shared, suppressing the amount of distortion of the cylinder head, improving the followability of the cylinder head movement, and fully compressing the bead part. To maintain the sealing effect even higher, and prevent corrosion and fouling of the elastic metal plate bead due to intrusion of high temperature and high pressure combustion gas, and rigidity of the cylinder head Or or cracks fart in the bead does not occur even by the large variation load stress generated in the lowest part,
This reduces the fluctuating load stress that occurs on the metal gasket as the internal combustion engine is started, operated, and stopped, and furthermore, when another elastic metal plate is stacked on the elastic metal plate, a complicated plate is formed on the convex side of the bead. Eliminating the thickness control, the necessary step is mainly obtained only by forming the folded part of the elastic metal plate,
An object of the present invention is to provide a metal gasket that further reduces the applied stress at the bead position and improves durability.

Further, in this metal gasket, when two elastic metal plates are combined, even if the bead positions of both elastic metal plates are slightly shifted, the bead portion is abnormally deformed and the sealing performance is deteriorated. However, the sealing performance of the bead portion is to be ensured by changing the radial width of the bead cylinder bore hole in both cases. Further, this metal gasket can cope with the size of the area between the cylinder bores by changing the shape of the bead according to the peripheral position of the cylinder bore. Further, by changing the structure of the metal gasket and the folded portion according to the peripheral position of the cylinder bore, the sealing performance required in the region between the cylinder bores and the other region can be satisfied. .

[0011]

SUMMARY OF THE INVENTION The present invention is configured as follows to solve the above-mentioned problems and achieve the above-mentioned object. That is, the present invention provides a bead comprising a plurality of cylinder bore holes, a folded portion obtained by folding the periphery of the cylinder bore hole radially outward, and a convex portion projecting toward the folded portion along the outside of the folded portion. A first elastic metal plate having a first elastic metal plate and a second elastic metal plate having a bead formed of a cylinder bore hole aligned with the cylinder bore hole of the first elastic metal plate and a convex portion abutting on the convex portion of the bead are laminated. The present invention relates to a metal gasket characterized by the above.

Further, the metal gasket is provided in the first gasket.
The radial width of the convex portion of the bead of the elastic metal plate is formed larger than the radial width of the convex portion of the bead of the second elastic metal plate.

Further, the metal gasket is provided in the first gasket.
The radial width of the bead of the elastic metal plate is increased over the entire circumference, the radial width of the bead of the second elastic metal plate is reduced in the region between the cylinder bores, and in the region other than between the cylinder bores. It is broader.

Further, the metal gasket is provided in the first gasket.
A soft member is interposed in the folded portion of the elastic metal plate.

In addition, the metal gasket is provided in the first gasket.
The folded portion of the elastic metal plate is formed thick at portions between the cylinder bores and thin at portions other than between the cylinder bores.

Alternatively, in the metal gasket, the bead is not formed in the first elastic metal plate and the second elastic metal plate in a region between the cylinder bore holes, and a portion other than the space between the cylinder bore holes is formed. The region is formed with the beads.

[0017]

The metal gasket according to the present invention is constructed as described above, and operates as follows. That is, the metal gasket has a bead formed along the cylinder bore hole at a position radially outward from the periphery of the cylinder bore hole and the periphery of the cylinder bore hole positioned on the convex side of the bead and inside the bead. And a second elastic metal plate having a bead that comes into contact with the bead of the first elastic metal plate is laminated, so that when tightened to a pressed state, Since the bead of the first elastic metal plate and the bead of the second elastic metal plate abut against each other, the inner and outer hem portions of the beads of the two elastic metal plates in the radial direction of the cylinder bore hole. A double annular seal is formed with respect to the opposing mounting surface at the position. Further, since the thickness of the folded portion is about twice the thickness of the first elastic metal plate, the annular portion overlaps with the periphery of the cylinder bore hole of the second elastic metal plate, and another annular seal is formed around the cylinder bore hole. Form a part. Therefore, four seal lines are formed between the cylinder bore holes when the beads are joined together, and three seal lines are formed in a region other than between the cylinder bore holes. Also, at the time of tightening, even if irregularities occur in the opposed mounting surfaces of the two structural portions, the beads and the second elastic metal plate or the folded portions are deformed in response to the distortion, and irregular gaps between the contact surfaces are reduced. Absorb.

In this metal gasket, the two elastic metal plates, the first elastic metal plate and the second elastic metal plate, exhibit the characteristics of a lap spring, and the reciprocal of the overall spring constant is the spring constant of each spring. It has the relationship of springs arranged in series, which is the sum of reciprocals. That is, the first elastic metal plate is compressed first and deforms to its yield point, and in the subsequent bending after the yield point of the thin spring, the thick second elastic metal plate bends at its high spring constant. , Indicating favorable spring characteristics over time in the tightening process.

Further, since the number of annular seal portions is increased, the variable load generated by the repetition of the combustion cycle of the internal combustion engine is shared and supported by the synergistic action with the absorption of the irregularity of the opposed mounting surface. The bead of the second elastic metal plate has a double structure in which the bead of the second elastic metal plate abuts each other on the protrusions and is laminated over the entire surface of both elastic metal plates. The stress becomes easier compared to the case of the elastic metal plate. The most advantageous condition in terms of stress is a case where two elastic metal plates having the same thickness are stacked. In addition, since the folded portion is integral with the metal gasket main body, there is no problem such as displacement when tightened and used.

[0020] The bead of the first elastic metal plate and the bead of the second elastic metal plate have a cylinder bore hole radial width of the bead of the first elastic metal plate that is equal to a radius of the cylinder bore hole of the bead of the second elastic metal plate. Since it is formed wider than the width in the direction, even if the positions of both beads slightly change, the contact state between the projections is maintained.

Further, while the radial width of the bead of the first elastic metal plate in the cylinder bore hole is uniformly widened, the radial width of the bead of the second elastic metal plate in the cylinder bore hole is set to:
By narrowing in the area between the cylinder bores and widening in the other areas, it is possible to reliably avoid misalignment of the beads in the area between the cylinder bores where strict sealing performance is required,
A reduction in sealing performance is prevented, and a sufficient sealing performance can be stably secured in such a region even in an internal combustion engine having a small distance between cylinder bores.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a metal gasket according to the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing one embodiment of a metal gasket according to the present invention. FIG. 2 is an enlarged view of the metal gasket in a region between the cylinder bores. This metal gasket is the first veneer
It is composed of an elastic metal plate and a second elastic metal plate, and is used, for example, for sealing a facing mounting surface between a cylinder head and a cylinder block (not shown) in a six-cylinder engine. For example, the first elastic metal plate located on the cylinder block side will be described as a lower bead plate 1 and the second elastic metal plate located on the cylinder head side will be described as an upper bead plate 8, but each elastic metal plate is limited to this arrangement. It is needless to say that the first elastic metal plate can be an upper plate and the second elastic metal plate can be a lower bead plate.

The lower bead plate 1 has, for example, a hardness of Hv200.
After subjecting the following materials to folding processing and bead processing, they are heat-treated in principle, but may be used without heat treatment. If not heat-treated, the material should be SUS
304, an aluminum alloy, a copper alloy or a mild steel plate is used. In the case of heat treatment, SUS is used as the precipitation hardening treatment.
630 or SUS631, SUS304 as nitriding treatment,
SUS301 or SK material (SK1~SK7), SUS420J ₂ and SUS44 as quenching and tempering treatment
It is made of a metal material such as a titanium alloy or an aluminum alloy as a solution heat treatment at 0A or a solution. The hardness of the material before bead processing is, for example, a material having an Hv of 200 or less.

A specific example of the hardness when the metal material of the upper bead plate 8 is subjected to each heat treatment is as follows. SUS3
04, when SUS301 is nitrided, H
v It is 200 or less (however, only the surface), but Hv350-400, SUS3
01 is Hv350-500 and SUS63
In the case where heat treatment, that is, precipitation hardening treatment, is performed after bead processing, Hv before the heat treatment is 200 or less,
v 350-500. SK material (SK1
～SK7) heat treatment and SUS420J ₂ quenching-tempering Further, titanium alloy, aluminum alloy (6A
1-2Sn-4Zr-6Mo) may be subjected to a solution heat treatment.

The lower bead plate 1 and the upper bead plate 8 in this metal gasket have six cylinders, that is, cylinder bore holes 2A, 2B, 2C corresponding to six cylinder bores formed in the cylinder block, respectively. ,
, 2F, and 9A, 9B, 9C,..., 9F are formed (see FIG. 1; these cylinder bore holes are generally denoted by reference numerals 2 or 9). Cylinder bore hole 2
A and 9A are formed in the same position and the same size,
The same applies to other cylinder bore holes. Further, the lower bead plate 1 and the upper bead plate 8 have water holes 3 through which cooling water passes,
A plurality of oil holes, oil return holes, knock holes, rivet holes, etc., are formed at the same position and in the same size. These are well known in the technical field of metal gaskets. So that
Here, detailed description is omitted.

In the example shown, the diameter of the cylinder bore is 8
5 mm, and the minimum distance between the cylinder bores is about 6 mm. The lower bead plate 1 is made of a material of SUS631 and has a thickness t of 0.12 mm.
A value within the range of 0.20 mm is preferable. The upper bead plate 8 is made of SUS631 and has a thickness t.
₃ is a value of 0.25 mm, but 0.20 mm to 0.3
A value within a range of 5 mm is preferable.

Although not shown, the heat and oil resistance of the front and back surfaces of the metal gasket, that is, all surfaces except the inside of the folded portion of the lower bead plate 1 and the entire surface of the upper bead plate 8 are improved. By applying a coating having a thickness of, for example, about 10 μ to 50 μ (preferably 25 μ) with a non-metal material such as rubber (for example, fluoro rubber) or resin, the cylinder head and the cylinder block are metal-to-metal. Can be avoided, and the corrosion resistance, durability and strength of the gasket can be ensured. Also, even if there are irregularities on the machined surface of the metal gasket,
The non-metallic material covers the unevenness and can achieve a sufficient sealing function.

FIG. 3 is a sectional view taken along line AA in FIG. 1, and FIG. 4 is a sectional view taken along line BB in FIG. FIG. 3 shows adjacent cylinder bore holes 2A, 2B and 9 respectively.
A and 9B are defined by the cylinder bore holes 2A and 2B.
And a cross section of the metal gasket cut along a line connecting the centers of 9A and 9B, that is, a cross section between the cylinder bores 2 and 9 is shown, but also at the boundary between the other adjacent cylinder bores 2 and 9. Of course, it has the same cross-sectional structure. In FIG. 4, the cylinder bore 2A
9A and the cross section of the metal gasket taken along the line connecting the end or edge of the metal gasket, the same applies to the cylinder bore holes 2B and 9B at the opposite positions. It has a cross-sectional structure, and it is needless to say that the same cross-sectional structure is not limited to these but also around the cylinder bores 2 and 9 other than between the cylinder bores 2 and 9.

As understood from these drawings, a bead 4 having a mountain-shaped cross section is formed so as to concentrically and annularly surround the vicinity of the cylinder bore 2 of the lower bead plate 1 of the metal gasket. (Reference numeral 4 indicates a generic term for beads). In the illustrated example, the distance L ₁ between the cylinder bore holes 2 adjacent, for example, about 6.0mm
It is. The bead 4 around the cylinder bore hole 2A and the bead 4 around the adjacent cylinder bore hole 2B overlap at the approaching portions of the cylinder bore holes 2A and 2B.
That is, the beads 4 are associated with each other in the region between the cylinder bores to form one bead. However, the adjacent beads 4 may be arranged at a slight gap without overlapping each other. The width L ₂ of the bead 4 as viewed in the radial direction has a width of about 2.5 mm, and a width of 1.0 mm which is the central area thereof.
Region L ₃ of the convex portion apex is substantially flat. The height of the bead 4 is 0.27 mm. Folded portions 5A and 5B are formed on the peripheral edge of the cylinder bore hole 2 formed in the lower bead plate 1 so as not to overlap the bead 4 on the convex side of the bead 4 and on the radially inner side of the bead 4. (Hereinafter, reference numeral 5 will be used to refer to a folded portion.) The width L ₄ of the folded portion 5 is, for example, about 1.2 mm.
It is. The cross-sectional structure of the metal gasket in the water hole 3 is deformed concentrically with the hole 3 so that the surrounding portion is slightly depressed (or mountain-shaped) from another planar portion.
At the time of tightening, it can be configured such that a sealing property is obtained around the hole 3.

In the metal gasket according to the present invention, in the above-described structure, in particular, a spring in which double elastic metal plates are arranged in series while securing a double seal line between the bead portion and the folded portion around the cylinder bore hole. To get the characteristics,
In addition, the irregularities that occur on the opposed mounting surfaces of the two structural parts are more easily absorbed by the deformation corresponding to the distortion of the bead and the folded part, and the complicated thickness control associated with stacking the metal plate on the elastic metal plate is eliminated. In order to obtain the necessary step only by forming the folded portion of the elastic metal plate and further reduce the load stress at the bead position and improve the durability, the lower bead plate 1
The upper bead plate 8 is superimposed over the entire surface of the lower bead plate 1 on the convex side of the bead 4. At this time, the protrusions of the beads 10 of the upper bead plate 8 are provided in such a direction that the protrusions of the beads 4 of the lower bead plate 1 come into contact with each other. In the illustrated preferred example, the thickness of the upper bead plate 8 is 0.25 mm, which is about twice the thickness of the lower bead plate 1. The height of the bead 10 is uniformly the same as the plate thickness around the cylinder bore hole.
There is a height on the order of 25 mm. Further, the width L of the bead 10
₅ is 2.0 mm in the area between the cylinder bore holes,
In other regions, the width gradually increases and reaches about 2.5 mm at the position shown in FIG. The upper bead plate 8 is only in contact with the protrusions of the beads 4 and 10 with respect to the lower bead plate 1, and is stacked with a gap in other areas. Furthermore, the upper bead plate 8 has substantially the same extent as the lower bead plate 1.

The metal gasket is interposed between the cylinder head and the cylinder block. For example, when the metal gasket is tightened by a bolt passing through the bolt hole 3 and brought into a pressed state,
A bead 4 provided in a peripheral portion of the lower bead plate 1 in the vicinity of the cylinder bore 2 contacts, for example, a joint surface of a cylinder head to form an annular seal portion. In addition, the folded part 5
Forms an annular seal portion inside the annular seal portion formed by the beads 4 with respect to the opposed mounting surface on the cylinder head side. The opposing mounting surface on the cylinder block side comes into strong contact with the lower bead plate 1, particularly at the portion of the upper bead plate 8 corresponding to the folded portion 5. The sealing pressure on the cylinder head and the cylinder block at the portion where the folded portion 5 exists increases as the thickness of the folded portion 5 increases. The two-stage concentric annular seal portion of the metal gasket prevents the high-temperature and high-pressure combustion gas from leaking from the cylinder bore 2 to the opposed mounting surfaces.

Further, when the cylinder head and the cylinder block are tightened, even if the mounting surface facing the cylinder head and the cylinder block is irregular, the spring constant is generally smaller when viewed in the height direction of the metal gasket. The lower bead plate 1 having a small thickness, which is an elastic metal plate, adapts to irregularities between the opposed mounting surfaces in response to deformation at an initial stage of small deflection. As described above, the increase in the annular seal portion of the metal gasket in a plan view and the absorption of the irregularity of the opposed mounting surface in the height direction of the metal gasket cause the combustion in the explosion / expansion stroke of the internal combustion engine. The amount of distortion of the cylinder head generated by the repetition during the cycle is suppressed. Folding part 5
Also, in addition to the bead 4, the abutment comes into contact with the opposing mounting surface, so that the tightening force is shared and supported by the bead 4 and the folded portion 5.
At the time of complete tightening, the combined spring constant is close to the spring having a large spring constant, that is, the spring constant of the upper bead plate 8, so that the opposed mounting surfaces can be tightly tightened and the metal gasket can be uniformly deformed. As a result, the stress generated in the bead 4 is homogenized / reduced to prevent the entire compression, and even if the above-described suppressed repetitive stress acts on the metal gasket due to the load fluctuation during the operation of the internal combustion engine, the bead 4 is generated. Since the applied load stress is reduced, it is possible to prevent bead settling and cracking.

Since the width of the bead 10 of the upper bead plate 8 is narrower than the width of the bead 4 of the lower bead plate 1, when the two elastic metal plates are combined, the position of the bead of the two elastic metal plates is reduced. Even if the beads 4 and 10 are slightly displaced from each other, the beads 4 and 10 can maintain a contact state with each other, so that the beads are not abnormally deformed and the sealing performance is not deteriorated. Also, since the folded portions 5A and 5B are located close to each other between the cylinder bore holes, a relatively strong seal can be secured, so that the width of the bead of the upper bead plate in such a region is different from that between the cylinder bore holes. Area is smaller than the width of the bead. Thus, the sealing performance of the bead portion is to be ensured according to the internal combustion engine by changing the radial width of the cylinder bore hole.

In order to adjust the thickness of the folded portion 5 formed on the lower bead plate 1, a predetermined compressive force is applied to the folded portion 5 to form a predetermined thickness 2t ₁ (= 2t-α). I do. Then, around the cylinder bore hole except for between the cylinder bore holes 2, the plate thickness is reduced by β which is a value larger than α by 2t ₂ (= 2t−β). That is, the rigidity of the cylinder head is lower than that of the cylinder block, and in a multi-cylinder engine, the portion between adjacent cylinder bores 2 is liable to undergo the largest distortion due to load fluctuations in the combustion cycle of the internal combustion engine during the explosion stroke and the expansion stroke. By the way. Therefore, since this portion is where the sealing function of the metal gasket is most likely to deteriorate, the folded portion 5
Structure of thickness 2t ₁ of the portion located between the cylinder bores hole 2 as shown in FIG. 3, the thickness 2t of the portion other than the adjacent cylinder bores holes 2 as shown in FIG. 4 ₂ (where, alpha <beta) The structure is such that the shape becomes thicker.

Specifically, as shown in FIGS. 14 and 15, in the area a between the cylinder bores 2,
The thickness 2t ₁ between the cylinder bores 2 is the thickest, the thickness gradually decreases in the region b extending on both sides of the region a, and the thickness of the arc portion c extending on both sides of the region a is reduced. 2t ₂ is formed thinnest.
In addition, the lower bead plate 1 on which the folded portion 5 is formed is heat-treated to adjust the hardness.
After the heat treatment, the hardness is set to 0 or less so that the lower bead plate 1 has a hardness corresponding to the type.

FIGS. 5 and 6 are sectional views of still another embodiment of the metal gasket according to the present invention. The metal gasket of this embodiment has the same configuration as that of the metal gasket shown in FIGS. 3 and 4 except that a soft metal plate 7 is interposed in the folded portion 5, and thus redundant description is omitted. In this embodiment, the thickness t ₃ (for example, 100
Soft metal plates 7A and 7B as soft members
(Hereinafter, it is indicated by reference numeral 7 in the generic name).
Therefore, the thickness of the folded portion 5 is 2t + t ₃ −α between the cylinder bores 2 after the pre-compression (the compression amount is α, β).
And 2t + t ₃ −β around the cylinder bore hole 2 except between the cylinder bore holes 2. Since β has a value larger than α, the thickness between the cylinder bores 2 is configured to be thicker than the thickness around the cylinder bore 2 except between the cylinder bores 2.

Various modifications of the soft metal plate 7 are conceivable. That is, as described with reference to FIGS. 14 and 15, the thickness of the folded portion 5 may be changed according to the position around the cylinder bore hole 2. The existence itself and the thickness can be changed in accordance with the peripheral position of 2. That is, as described above, only the portion between the cylinder bores 2 is formed thick and the portion other than between the cylinder bores 2 is formed thin,
For example, the soft metal plate 7 may be arranged over the entire circumference of the folded portion 5, or may be arranged only in a portion between the cylinder bores 2. In production, in the step of forming the folded portion 5, the soft metal plate 7 is sandwiched between the folded portions 5, and a compressive force is applied to form the sheet into a predetermined thickness.
Finally, the elastic metal plate 1 having the folded portion 5 and the soft metal plate 7 sandwiched therebetween are heat-treated to adjust the hardness.

The soft metal plate 7 is provided to adjust the difference in thickness between the area around the cylinder bore 2 and the area radially outward from the bead 4. For example, when the thickness of the folded portion 5 is largely reduced around the cylinder bore hole 2 due to the pre-compression, the soft metal plate 7 is laminated on the convex side surface of the bead 4 and is sandwiched between the folded portions 5. And the step between the bead 4 and the radially outer region beyond the bead 4 are increased.

In the embodiment shown in FIGS. 3 to 6, the width of the bead 4 of the lower bead plate 1 in the radial direction of the cylinder bore is made larger than the width of the bead 10 of the upper bead plate 8. However, the present invention is not limited to this. The widths of the beads 4 and 10 may be equal.

FIGS. 7 and 8 show still another embodiment of the metal gasket according to the present invention, respectively.
It is sectional drawing in A and BB. In this example,
The lower bead plate 11 and the upper bead plate 18 are made of the same material and have the same thickness. The shape of the bead 14 of the lower bead plate 11 and the shape of the bead 19 of the upper bead plate 18 are the same, and are arranged symmetrically with respect to the joining surface. Folding part 5A, 5
Except for the formation of B, there is no difference in the production of both bead plates. Since the plate thicknesses t of the bead plates 11 and 18 are the same, the stress acting on both the bead plates 11 and 18 at the time of tightening is equally shared. Therefore, the metal gasket is in the mildest state in terms of stress.

FIGS. 9 and 10 correspond to FIGS. 7 and 8, respectively.
FIG. 3 is a cross-sectional view similar to the embodiment shown in FIG. 1, but showing a further embodiment of the metal gasket according to the invention, taken along lines AA and BB in FIG. In this embodiment, FIG.
Similarly to the embodiment shown in FIG. 8, the lower bead plate 11 and the upper bead plate 18 are made of the same material and have the same thickness. The bead 14 of the lower bead plate 11 is formed wider than the bead 19 of the upper bead plate 18 in the radial direction of the cylinder bore. Therefore, the spring constant of the lower bead plate 11 is reduced accordingly. As in the case of the embodiment shown in FIGS. 3 to 6, even if the positions of the beads 14 and 19 of the two elastic metal plates are slightly shifted when the two bead plates 11 and 18 are combined, the beads 14 and 19 are formed. It does not deform abnormally and does not lower the sealing performance.

Further, another embodiment of this metal gasket will be described with reference to FIGS. FIG. 11 is a plan view showing another embodiment of the metal gasket.
FIG. 12 is a cross-sectional view showing one embodiment along line AA in FIG. From FIG. 11, the folded portion 5 is provided all around the cylinder bores 2 and 9, but the beads 4, 1
0 is the cylinder bore hole 2 other than between the cylinder bore holes 2 and 9;
9 is formed around the cylinder bores 2, 9.
9, no bead is formed in a region between the cylinder bores 2 and 9. In this embodiment, for example, there is no change in the structure around the cylinder bores 2 and 9 as compared with the metal gasket shown in FIGS. 3 and 4, but the structure in the region between the cylinder bores 2 and 9 is different. Things. That is, in this embodiment, no bead is formed in the lower bead plate 1 and the upper bead plate 8 in the region between the cylinder bores 2 and 9 as compared with the embodiment shown in FIG. Therefore, the folded portion 5 of the lower bead plate 1 comes into contact with the facing surface of the upper bead plate.

Referring to FIGS. 11 and 13, a further embodiment of the metal gasket will be described. FIG.
FIG. 12 is a cross-sectional view illustrating another example taken along line AA in FIG. 11. This embodiment does not change the structure around the cylinder bores 2 and 9 as compared with the embodiment of FIGS. 5 and 6, but differs in the structure in the region between the cylinder bores 2 and 9. That is, the embodiment shown in FIG.
Compared to the one shown in FIG. 5, no bead is formed in the lower bead plate 1 and the upper bead plate 8 in the region between the cylinder bores 2 and 9. In addition, a soft metal member 7 is interposed in the folded portion 5 around the cylinder bores 2 and 9.

Although the embodiments of the present invention have been described with reference to a six-cylinder internal combustion engine, the present invention is not limited to this type of internal combustion engine, but is applied to, for example, a three-cylinder or four-cylinder internal combustion engine. Various modifications and changes are possible within the scope of the technical idea constituted by the matters described in the claims of this application. In the illustrated example, the thickness of the lower bead plate and the thickness of the upper bead plate are set to be thinner in the lower bead plate and thicker in the upper bead plate. Alternatively, the thickness of both bead plates may be the same. It is most advantageous in terms of stress if both bead plates have the same thickness.

[0045]

The metal gasket according to the present invention is configured as described above and has the following effects. That is, this metal gasket was composed of a plurality of cylinder bore holes, a folded portion obtained by folding the periphery of the cylinder bore hole outward in the radial direction, and a convex portion projecting toward the folded portion along the outside of the folded portion. 1st with bead
Since the elastic metal plate and the second elastic metal plate having a bead constituted by a cylinder bore hole aligned with the cylinder bore hole of the first elastic metal plate and a convex portion abutting on the convex portion of the bead are laminated, When a metal gasket is tightened and pressed between the cylinder head and the cylinder block, which are two structural parts having the mounting surface, the first
The elastic metal plate and the second elastic metal plate are deformed by the pressing force, but since each of the beads has a protruding portion in contact with each other, the inner and outer skirts of the beads of both elastic metal plates in the radial direction of the cylinder bore hole are formed. A double annular seal portion is formed with respect to the opposed mounting surface at the position of the portion. Further, since the thickness of the folded portion is about twice the thickness of the elastic metal plate, another annular seal portion is formed around the cylinder bore hole so as to overlap with the periphery of the cylinder bore hole of the second elastic metal plate. I do.

Therefore, in the region between the cylinder bores, when the beads are joined together, four seal lines are formed, and a reliable seal is provided between the cylinder bores requiring a strong sealing force. Can be provided.
In addition, three seal lines are formed in a region other than between the cylinder bore holes, and a reliable seal can be ensured also in this region. In addition, since the folded portion is integral with the metal gasket main body, there is no problem such as displacement when tightened and used.

The two elastic metal plates, the first elastic metal plate and the second elastic metal plate, exhibit the characteristics of a lap spring, and the reciprocal of the overall spring constant is equal to the sum of the reciprocals of the spring constants of the individual springs. Have the relationship of springs arranged in series. In general, the spring constant is almost proportional to the cube of the plate thickness. Therefore, if there is a sufficient difference in the thickness of the metal plate, theoretically the overall spring constant is close to the spring constant of the thinner spring. The first elastic metal plate is compressed first and deforms to its yield point in the initial deflection, and the second elastic metal plate is thicker in subsequent deflections after the yield point of the thin spring. Will flex with its high spring constant and exhibit favorable spring characteristics over time in the tightening process. That is, even if irregularities occur in the opposing mounting surfaces of the two structural parts when the metal gasket is tightened, the bead, the second elastic metal plate, and the folded portion are deformed in response to the distortion by the above-described skillful deformation, and Absorbs irregular gaps between contact surfaces. In use after completion of tightening, the tightening between the opposing mounting surfaces is large and reliable because of a large combined spring constant corresponding to the deformation of the upper bead plate having a large spring constant. Due to the above-mentioned arrangement in series, the followability to the movement of the cylinder head is improved.

Further, in this metal gasket, since the number of annular seal portions is increased, each seal portion shares a variable load due to the repetition of the combustion cycle of the internal combustion engine to suppress the amount of distortion of the cylinder head, Prevents full compression of the bead, thereby preventing a reduction in sealing effect. Further, compared to the case where only one elastic metal plate is used, the stress generated in the elastic metal plate is reduced, and the durability is improved. Therefore, corrosion of the bead of the elastic metal plate due to intrusion of the high-temperature and high-pressure combustion gas,
In addition to preventing fouling, the bead does not set or crack due to the large fluctuating load stress generated in the least rigid part of the cylinder head, and it occurs with the operating state of the internal combustion engine such as start, operation and stop. Therefore, the amount of distortion of the cylinder head is suppressed, and the fluctuating load stress based on the distortion can be reduced. Further, when the metal plate is stacked on the elastic metal plate, by overlapping both beads so that the convex portions are in contact with each other, complicated plate thickness management caused by the thickness and height of the folded portion, the bead, and the metal plate is eliminated. At the same time, the necessary step can be obtained mainly by forming only the folded portion of the elastic metal plate, the plate thickness can be easily controlled, and the load stress at the bead position can be further reduced to improve the durability.

In the metal gasket, the bead of the elastic metal plate and the bead of the another elastic metal plate are brought into contact with each other at the protruding portions, but the width of the bead of the elastic metal plate in the cylinder bore hole radial direction is different. Because the elastic metal plate is formed wider than the radial width of the cylinder bore hole of the bead, when two elastic metal plates are combined, even if the bead position of both elastic metal plates is slightly shifted, the bead part is abnormal And there is no possibility that the sealing performance is degraded. Therefore, even if the positions of both beads slightly change, the contact state between the projections is maintained.

Further, while the radial width of the bead of the elastic metal plate in the cylinder bore hole is uniformly increased, the radial width of the bead of the another elastic metal plate in the cylinder bore hole is reduced in a region between the cylinder bore holes. By increasing the width in other areas, the gap between the cylinder bores where the sealing performance is strictly required can be reliably prevented from shifting between the beads, and the deterioration of the sealing performance is prevented. Such an effect that a sufficient sealing force can be stably obtained in the region between the cylinder bores is particularly effective in the case of an internal combustion engine having a small distance between the cylinder bores.

Further, when the metal gasket sandwiches the soft member between the folded portions of the elastic metal plate, the bead deformation can be increased as compared with the case where the soft member is not sandwiched. Therefore, the thickness at the folded portion increases, so that the surface pressure distribution in the metal gasket can be appropriately compensated, and the balance with the surface pressure of the bead portion can be achieved.

Further, since the folded portion is subjected to a heat treatment after molding, it can be worked freely, and can be machined by appropriately changing the width of the folded portion in the radial direction of the cylinder bore hole. For example, the thickness of a portion located in a region between adjacent cylinder bores can be made thicker than the thickness of a portion other than between the cylinder bores. Due to the curvature on the cylinder head side, the distortion is most likely to occur between adjacent cylinder bores, so that a large tightening force is obtained when tightening the metal gasket at the part between the cylinder bore holes where the combustion gas leaks most easily, and the sealing performance is improved. It is possible to prevent corrosion and fouling of the bead.

In a metal gasket obtained by applying a heat-resistant and oil-resistant non-metallic material such as rubber or resin to the outer surface of the metal gasket, direct metal-to-metal transfer between the gasket and the cylinder head and cylinder block is performed. Contact and corrosion resistance against corrosive combustion gas, as well as durability and precision, are ensured. Corrosion and fouling of the metal surface are prevented, and irregularities on the surface of the cylinder head and cylinder block ( A sufficient sealing function can be ensured for the machined surface).

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a metal gasket according to the present invention.

FIG. 2 is an enlarged plan view showing a portion between cylinder bores of the metal gasket of FIG. 1;

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view taken along line BB in FIG. 1;

FIG. 5 is another embodiment of the metal gasket according to the present invention, and is a cross-sectional view taken along line AA of FIG. 1;

6 is the metal gasket of FIG.
It is sectional drawing in B.

7 is still another embodiment of the metal gasket according to the present invention, and is a cross-sectional view taken along line AA of FIG. 1;

8 is the metal gasket of FIG.
It is sectional drawing in B.

FIG. 9 is still another embodiment of the metal gasket according to the present invention, and is a cross-sectional view taken along line AA of FIG. 1;

10 is a view showing the metal gasket of FIG. 9 and a line B of FIG. 1;
It is sectional drawing in -B.

FIG. 11 is a plan view showing still another embodiment of the metal gasket according to the present invention.

FIG. 12 is a cross-sectional view showing one embodiment of the metal gasket of FIG. 11 along line AA of the present invention.

FIG. 13 is a sectional view showing another embodiment of the metal gasket of FIG. 11 along line AA of the present invention.

FIG. 14 is an explanatory diagram in which the thickness of the folded portion of the bead plate is changed according to the position around the cylinder bore.

FIG. 15 is the same explanatory diagram as FIG. 14;

FIG. 16 is a partial sectional view of a metal gasket disclosed in the prior application of the present applicant.

FIG. 17 is a sectional view of another portion of the metal gasket of FIG.

FIG. 18 is a partial sectional view of a metal gasket disclosed in another prior application filed by the present applicant.

FIG. 19 is a sectional view of another portion of the metal gasket of FIG. 18;

[Explanation of symbols]

 Reference Signs List 1 lower bead plate (first elastic metal plate) 2 cylinder bore hole of lower bead plate 4 bead of lower bead plate 5 folded part of lower bead plate 7 soft metal plate 8 upper bead plate (second elastic metal plate) 9 upper bead plate Cylinder bore hole 10 Bead of upper bead plate 11 Lower bead plate (first elastic metal plate) 14 Bead of lower bead plate 18 Upper bead plate (second elastic metal plate) 19 Bead of upper bead plate

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kuniyoshi Inoue 248 Kano, Higashiosaka-shi, Osaka Japan Gasket Co., Ltd. (56) References JP-A-62-155374 (JP, A) 34562 (JP, U) Japanese Utility Model Showa 57-199183 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16J 15/08 F02F 11/00

Claims (6)

(57) [Claims] 1. A bead comprising a plurality of cylinder bores, a folded portion obtained by folding a peripheral edge of the cylinder bore in a radially outward direction, and a convex portion projecting toward the folded portion along the outside of the folded portion. A first elastic metal plate;
A metal gasket comprising: a second elastic metal plate having a bead formed of a cylinder bore hole aligned with the cylinder bore hole of an elastic metal plate and a convex portion abutting on the convex portion of the bead; 2. A method according to claim 1, wherein a radial width of said convex portion of said bead of said first elastic metal plate is formed larger than a radial width of said convex portion of said bead of said second elastic metal plate. The metal gasket according to claim 1. 3. The radial width of the bead of the first elastic metal plate is increased over the entire circumference, and the radial width of the bead of the second elastic metal plate is reduced in a region between the cylinder bores. The metal gasket according to claim 1, wherein the metal gasket is widened in a region other than between the cylinder bores. 4. The metal gasket according to claim 1, wherein a soft member is interposed in the folded portion of the first elastic metal plate. 5. The metal gasket according to claim 1, wherein the folded portion of the first elastic metal plate is formed thick at portions between the cylinder bores and thin at portions other than between the cylinder bores. . 6. The first elastic metal plate and the second elastic metal plate do not have the bead formed in a region between the cylinder bores, and have the bead formed in a region other than between the cylinder bores. The metal gasket according to claim 1, wherein the metal gasket is formed.