JPH09229198A - Metal gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the sealing function by furnishing multifold seal lines through formation of stopper beads on a pair of base boards for beads, to prevent the combustion gas from intruding into the beads, allow to exert a stopper function for beads, and heighten the stiffness of the stopper beads. SOLUTION: A metal gasket concerned is structured so that beads 3, 4 and stopper beads 5, 6 are provided on bead base boards 1, 2 along holes 7. The stopper beads 5, 6 are formed as overlapping one over another in the pressed condition as in service, and the stiffness of the stopper beads 5, 6 is secured even if the base boards 1, 2 are fabricated from a thin resilient metal sheet. The obtained gasket is equipped with a stopper function to preclude total compression of the beads 3, 4 and a sealing function to prevent the combustion gas from intruding to the beads 3, 4, and also with an enhanced durability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal gasket which is interposed between opposed surfaces of parts in a multi-cylinder engine and seals the parts.

[0002]

2. Description of the Related Art Conventionally, structural members of an engine such as an aluminum alloy cylinder head and a cylinder block are light in weight, but have low rigidity, so that relative displacement tends to increase between the two when the engine is operating. Therefore, the metal gasket that seals between the opposing mounting surfaces of both structural members is made of an elastic metal plate with a bead formed in the vicinity of the periphery of the through hole corresponding to the cylinder bore, that is, the passage for the combustion chamber, water, oil, etc. There is.

Conventionally, a metal gasket made of a metal material has been used to seal between opposed surfaces of a cylinder head and a cylinder block in an engine. The metal gasket has a bead in the vicinity of the periphery of the through hole corresponding to the passage of the cylinder bore, water, and oil. An elastic annular contact portion is formed to seal the opposing surfaces.

However, recent engines are required to have higher output and lighter weight, and as a part thereof, there is a tendency to manufacture the cylinder head and the cylinder block from conventional steel having a large specific gravity or aluminum alloy having a small specific gravity instead of casting. It is in. Although the aluminum alloy is lightweight, it has a low rigidity, so that the relative displacement of the cylinder head with respect to the cylinder block tends to increase during engine operation.
When tightening the facing surfaces of the cylinder head and the cylinder block with the tightening bolts via the single-plate metal gasket, the tightening bolt positions are dispersed on the outer peripheral portion or the relatively outer peripheral portion of the metal gasket. Since the combustion chamber holes are not necessarily evenly distributed around them, the facing surfaces are likely to be irregular. As a result, the high-temperature and high-pressure combustion gas penetrates into the opposing surfaces of the places with large strain, such as the portions between the combustion chamber holes, and corrodes or contaminates the bead of the metal gasket interposed between the opposing surfaces. Reduces the sealing effect.

Further, in the case of the cylinder head gasket, the distance between the cylinder head and the cylinder block is repeatedly increased and decreased during the combustion cycle of the engine, and the metal gasket is repeatedly subjected to stress, that is, mechanical stress or thermal stress. The load fluctuation stress of the engine is
It occurs as a large value in the lowest rigidity portion of the cylinder block or cylinder head, and as a result, there occurs a problem that the bead becomes fatigued or cracks occur to deteriorate the sealing performance.

The metal gasket disclosed in Japanese Patent Laid-Open No. 5-39868 is formed by laminating a first elastic metal plate having a bead and a folded portion and a second elastic metal plate having a bead. The beads are abutted against each other. In this metal gasket, the beads of two elastic metal plates are arranged in series, so that even if irregularities occur on the two opposing surfaces during tightening, the beads and folded portions will deform in response to strain and absorb the irregularities. However, in use after tightening, the variable load due to the repetition of the combustion cycle of the internal combustion engine is shared, and the distortion amount of the cylinder head is suppressed,
It follows the movement of the cylinder head well and prevents the bead from being fully compressed to maintain a high sealing effect.
The folded part of the elastic metal plate prevents the bead from corroding or fouling due to the intrusion of high-temperature and high-pressure combustion gas, and the bead sags and cracks due to the large fluctuating load stress generated in the least rigid part of the cylinder head. Instead, by combining the plate thickness of the two elastic metal plates and forming the folded portion, the stopper function can be exhibited, the load stress at the bead position is reduced, and the durability is improved.

[0007]

However, since the metal gasket made of the elastic metal plate having the folded portion forms the folded portion on the elastic metal plate, it is very expensive to form the folded portion on the elastic metal plate. It is necessary to use a material that requires high processing accuracy and has good workability in the folded portion, for example, a material having high elongation, low hardness, and low tensile strength. Alternatively, since the folded portion is formed on the elastic metal plate, it is necessary to heat the elastic metal plate to increase the material strength after forming the folded portion on the elastic metal plate, and it is necessary to use an expensive material. Becomes complicated and the cost increases. In addition, since the workability of the folded portion on the elastic metal plate is high, there is a problem that cracks are likely to occur at the folded portion.

Further, in the metal gasket, since the plate thickness of the elastic metal plate having the folded-back portion is added to the plate thickness of the folded-back portion as it is, in the region around the combustion chamber and other regions,
The plate thickness difference becomes large, the selection of the plate thickness of the elastic metal plate is limited from the viewpoint of the balance of the surface pressure, and the degree of freedom in design is reduced. For example, the plate thickness of the elastic metal plate is 0.10 to 0.15 mm. Is the limit. Therefore, in the metal gasket, when the folded-back portion is formed, the surface pressure around the combustion chamber hole is likely to concentrate, and even if the folded-back portion has a two-sheet structure, it is compressed to a 1.5-sheet configuration.

[0009]

SUMMARY OF THE INVENTION An object of the present invention comprises a pair of bead substrates made of an elastic metal plate having beads along the holes, and the bead substrates are opposed to each other in a free state. A stopper bead in a contact state or in a contact state is formed, and a multiple seal line consisting of a bead seal line and a stopper bead seal line is formed along the combustion chamber hole to improve the sealing function. Further, the bead substrates are compared. In order to compensate for the lack of rigidity of the stopper bead formed on the bead substrate when the elastic bead is made of a thin plate, for example, an elastic metal plate of about 0.2 to 0.3 mm, both stopper beads are overlapped, The stopper function of the stopper bead prevents the bead from being fully compressed,
It is an object of the present invention to provide a metal gasket in which combustion gas is prevented from entering the bead by the stopper bead sealing function and the durability of the bead is improved.

According to the present invention, there is provided a first bead substrate made of an elastic metal plate having first beads formed along the parallel holes, and a first bead substrate made of elastic metal plates having second beads formed along the parallel holes. A second bead substrate, the first bead and the second bead are arranged to face each other, and the first bead substrate is located on the hole side with respect to the first bead protruding in the same direction as the first bead. A first stopper bead is formed along the hole, and the second bead substrate has the same direction as the first stopper bead and the second stopper bead.
A second stopper bead is formed along the hole on the hole side of the second bead protruding in the direction opposite to the bead, and the heights of the first and second stopper beads are the same as those of the first and second beads. The present invention relates to a metal gasket formed to be lower than the height.

The first stopper bead and the second stopper bead
The stopper beads are separated from each other in a free state where they are not pressed. Alternatively, the first stopper bead and the second stopper bead overlap each other in a non-pressed free state.

A half bead extending toward the first bead substrate is formed between the second bead and the second stopper bead of the second bead substrate.
Therefore, the height of the half bead is equal to the height of the first and second portions.
The stopper beads can come close to each other in a free state where they are not pressed.

Alternatively, a first half bead is formed between the first bead of the first bead substrate and the first stopper bead, and the second bead and the second stopper bead of the second bead substrate are formed. A second half bead is formed between and. Therefore, the first and second stopper beads are brought close to each other by the height of the first and second half beads in the non-pressing free state, and the first and second stopper beads are brought into contact with each other in the non-pressing free state. It can be configured to overlap.

Further, the first bead formed on the first bead substrate and the second bead formed on the second bead substrate project in a direction opposite to each other and are in contact with each other. Alternatively, the first bead formed on the first bead substrate and the second bead formed on the second bead substrate extend in the same direction and overlap each other.

This metal gasket is, as described above,
Since the stopper beads formed on the bead substrate are formed so as to overlap each other in the pressed state during use, even if the bead substrate is made of a thin elastic metal plate, the rigidity of the stopper bead does not become insufficient, and The stopper bead can perform a stopper function and a sealing function for the bead.

In this metal gasket, when the stopper bead is formed so as to protrude toward the bead substrate facing the bead substrate at a height less than the height of the bead, the stopper bead is formed between the bead substrates. The dead space can be further reduced, and the stopper bead prevents gas from entering the bead,
It is possible to improve the sealing performance and prevent the bead from getting settled or cracked. In addition, the metal gasket can be configured by the two bead substrates by providing the bead substrate with the stopper beads, the number of layers can be reduced, and the number of parts can be reduced.

Therefore, this metal gasket prevents the bead from being fully compressed and protects it by simply forming the stopper bead on the bead substrate provided with the bead made of two elastic metal plates. Sealing property can be secured, the function of the bead is always properly exhibited, the stopper bead performs a sealing function with respect to the bead, the durability of the bead is improved, and a space member or an intermediate plate as in the past is required. Without reducing the number of parts,
It is inexpensive and can improve reliability.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a metal gasket according to the present invention will be described. Although not shown, this metal gasket is preferably applied to a head gasket sandwiched between a cylinder head and a cylinder block to seal between opposing surfaces. The metal gasket has combustion chamber holes, that is, holes formed in parallel with cylinder bores formed in the cylinder block. This metal gasket has a plurality of holes formed in parallel so that it can be applied to a multi-cylinder engine such as a 4-cylinder or a 6-cylinder. In the drawings showing the respective embodiments to be described below, the reference numerals indicating the parts and portions are given the same reference numerals for the parts and portions having the same configuration and the same function, and the duplicated description will be omitted.

First, the metal gasket according to the present invention will be described with reference to FIGS. FIG. 1 is a partial plan view showing a first embodiment of a metal gasket according to the present invention, FIG. 2 is an enlarged plan view of one bead substrate of the metal gasket of FIG. 1 at reference numeral C, and FIG. 3 is a metal gasket of FIG. FIG. 4 is an enlarged plan view of the other bead substrate of the gasket at reference numeral C, and FIG. 4 is a cross-sectional view showing an embodiment of the metal gasket of FIG. 1 taken along the line AA.

This metal gasket is a bead substrate 1 made of an elastic metal plate in which combustion chamber holes, that is, holes 7 corresponding to combustion chambers formed in parallel in a multi-cylinder engine are formed.
2 is comprised. A plurality of bolt holes 12, water holes 13, blow-by holes 14, knock holes, and oil holes 16 are formed around the holes 7 in the bead boards 1 and 2.
Beads 3 and 4 each having a convex cross section are formed on the bead substrates 1 and 2 along a hole 7 formed in the bead substrates 1 and 2 so as to be substantially concentric with the hole 7 and annularly surround it. Bead boards 1 and 2
Are arranged in a stacked state with the beads 3 and 4 facing each other. Each of the beads 3 and 4 has a convex surface 17 formed on its top surface, and the convex surfaces 17 face each other and are arranged in contact with each other.

In this metal gasket, the bead substrates 1 and 2, particularly the beads 3 and 4 in the same direction as the projecting direction of the beads 3 and 4 along the hole 7 on the hole 7 side from the beads 3 and 4.
Stopper beads 5 and 6 are formed so as to project to a height less than the height of 4. Further, the stopper beads 5 and 6 are formed so as to face each other so as to overlap each other in the pressed state during use. The stopper beads 5, 6 extend along the hole 7 in regions which are aligned with each other at the same distance from the bore or the hole 7. Further, a half bead 23 extending toward the bead substrate 1 is formed between the bead 4 of the bead substrate 2 and the stopper bead 6. In the beads 3 and 4 formed on the bead substrates 1 and 2, adjacent beads 3 and 4 in the region between the holes 7 are associated with each other to form a single bead 20. Further, the stopper beads 5 and 6 formed on the bead substrates 1 and 2 are independently formed without the adjacent stopper beads 5 and 6 in the region between the holes 7 being associated with each other. Further, in this metal gasket, the stopper beads 5 and 6 formed on the bead substrates 1 and 2 are spaced apart in the non-pressed state when not in use (free state), and the bead is pressed in the pressed state during use. Boards 1, 2
The stopper beads 5 and 6 formed in the above are in a state of overlapping each other.

With this structure, the metal gasket has a double seal line at two points, the bead 3, 4, the stopper bead 5, and the stopper bead 6, and thus has an extremely strong sealing structure. Further, the stopper beads 5 and 6 formed on the bead substrates 1 and 2 are formed to have a lower height and a smaller bead width than the beads 3 and 4, and have rigidity higher than the beads 3 and 4 and the beads 3 and 4. Since it becomes more difficult to deform, it serves as a stopper function for preventing the beads 3 and 4 from being fully compressed. Further, in this metal gasket, even if the bead substrates 1 and 2 are made of thin elastic metal plates, for example, elastic metal plates of about 0.2 to 0.3 mm, the stopper beads 5, 6 are pressed in a pressed state during use. Since they overlap each other, the rigidity of the stopper beads 5 and 6 does not become insufficient, and when tightened between the cylinder head and the cylinder block, the sealing function and the stopper function can be performed between the contact surfaces.

In this metal gasket, the bead substrates 1 and 2 can be formed to have the same thickness within the range of 0.2 to 0.3 mm, but in some cases, The plate thicknesses of the bead substrates 1 and 2 may be different from each other in consideration of the positional relationship between the cylinder block side and the cylinder head side. Further, the heights of the stopper beads 5 and 6 formed on the bead substrates 1 and 2 are as follows.
It is also possible to appropriately change each other in order to adjust the surface pressure generated in 1. By changing the plate thickness of the bead substrates 1 and 2 and the height of the stopper beads 5 and 6, the degree of freedom in combination and design is increased. Further, the heights of the beads 3 and 4 formed on the bead substrates 1 and 2 can be made higher in the region between the bores, that is, between the holes 7, and lower in the other regions. When the metal gasket is tightened between the cylinder block and the cylinder head, the surface pressure generated by the beads 3 and 4 and the stopper beads 5 and 6 is adjusted to a height and a plate thickness so as to match the rigidity of the cylinder head. By changing it, it is possible to control to an appropriate surface pressure.

In this metal gasket, the bead substrates 1 and 2 are made of SUS301, for example. As shown in FIG. 9, a surface of an elastic metal plate forming the bead substrates 1 and 2 is coated with a heat-resistant and oil-resistant non-metal layer to a thickness of, for example, about 10 to 50 μm to form a cylinder head and a cylinder block. On the other hand, the metal-to-metal contact state is avoided, and the corrosion resistance, durability and strength of the metal gasket are secured. For example, both surfaces of the bead substrate 1 and the lower surface of the bead substrate 2 are coated with fluororubber 10 having heat resistance and oil resistance,
Further, on the fluororubber 10, the acrylic silicone resin 11
Is coated. The non-metal layer coated on the surfaces of the bead substrates 1 and 2 can cover the irregularities when the bead substrates 1 and 2 are machined, and can perform a sufficient sealing function.

Next, a second embodiment of the metal gasket according to the present invention will be described with reference to FIG. In the second embodiment, the half beads 24 formed on one of the bead substrates 2 are used.
Has a height that extends until the stopper beads 5 and 6 formed on the bead substrates 1 and 2 overlap each other in a non-pressed state when not used (free state). In the second embodiment, as in the first embodiment, a double seal line is formed at two places of the beads 3 and 4, the stopper bead 5 and the stopper bead 6, and an extremely strong sealing function and stopper function are achieved. You can

Next, a third embodiment of the metal gasket according to the present invention will be described with reference to FIG. In the third embodiment, a half bead 25 extending toward the bead substrate 2 is formed between the bead 3 of the bead substrate 1 and the stopper bead 5, and between the bead 4 and the stopper bead 6 of the bead substrate 2. Half beads 26 extending toward the bead substrate 1 are formed. The half beads 25 and 26 formed on the bead substrates 1 and 2 in the third embodiment are the second beads.
Half beads 2 formed on the bead substrate 2 in the example
Compared with 4, the height of the half beads 25, 26 may be lower than the height of the half beads 24. Therefore, in the third embodiment, the deviation between the bead substrates 1 and 2 in the pressed state can be made smaller than that in the second embodiment.

Next, a fourth embodiment of the metal gasket according to the present invention will be described with reference to FIG. In the fourth embodiment, the beads 3 and 4 and the stopper beads 5 and 6 are formed on the bead substrates 1 and 2, the half beads are not formed, and the bead is in a non-pressed state when not in use (free state). The stopper beads 5 and 6 formed on the substrates 1 and 2 are formed so as to be spaced from each other. The stopper beads 5 and 6 formed on the bead substrates 1 and 2 are double in a state of overlapping with each other during use, and the stopper beads 5 and 6 themselves can reinforce each other to sufficiently perform the function. Further, in the fourth embodiment, as in the first embodiment, the beads 3,
8. A double seal line is formed at two points, 8, the stopper bead 5 and the stopper bead 6, so that an extremely strong sealing function and a stopper function can be achieved.

Next, a fifth embodiment of the metal gasket according to the present invention will be described with reference to FIG. In the fifth embodiment, the bead substrates 1 and 2 are formed to have the same shape, and the beads 3 and 4 and the stopper beads 5 and 6 on the bead substrates 1 and 2 overlap each other. That is, the bead 3 formed on the bead substrate 1 and the bead 4 formed on the bead substrate 2 extend in the same direction and overlap each other.

[0029]

As described above, in the metal gasket according to the present invention, the bead and the stopper bead are formed on the bead substrate. Therefore, the stopper bead is doubled at the time of use to compensate for the lack of rigidity of the stopper bead itself. In addition, the stopper bead can configure a small dead space in the vicinity of the hole formed between the bead substrates, and the multiple seal lines are formed to improve the sealing property, and the gas to the bead can be improved. It can prevent intrusion and prevent the bead from being settled or cracked due to corrosion by gas. In addition, the stopper bead can perform a stopper function to prevent the compression of the bead to the full extent, and prevent the bead from settling. By providing the stopper bead, this metal gasket can fulfill the same sealing function and surface pressure adjusting function as those of the conventional folded portion, and there is no material limitation as compared with the folded portion. The manufacturing cost can be reduced and the durability can be significantly improved. In this metal gasket, in particular, the stopper beads formed on the bead substrates overlap each other in a pressed state during use, so that even if the bead substrate is made of a thin elastic metal plate, the rigidity of the stopper bead is sufficient. Can be secured.

That is, the stopper bead formed on both bead substrates has a function of preventing the bead from being completely compressed, a function of absorbing imperfections on the opposing surfaces of the cylinder head and the cylinder block, and a sealing function for protecting the bead. A compensating part having is formed, which prevents the bead from sagging or cracking due to the overcompression of the bead, and prevents the combustion gas from flowing into the bead side by the stopper bead to corrode the high temperature gas. The bead is protected from the like, and the deterioration of the function of the bead is prevented.

This metal gasket does not use a separate member such as a spacer for forming the compensating portion, and it is not necessary to manufacture a separate member, and it can be constituted by only a pair of the bead boards, and the number of parts is reduced. It is possible to reduce the number of processing steps, reduce the number of processing steps, and have a simple processing shape, so not only can the manufacturing cost be greatly reduced, but also the processing accuracy of parts can be improved, the cumulative error can be reduced, and the height of the stopper bead can be reduced. Can be easily controlled, the sealing performance can be improved by reducing the number of layers, and a highly reliable product can be provided. In addition, since the stopper bead forms the compensating portion, it is not a structure in which the folded portion is provided at the hole-side edge of the bead substrate without forming the folded portion. It is not necessary, and there is no need to take measures to generate a crack in the folded portion, and the manufacturing cost can be reduced.

[Brief description of drawings]

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

FIG. 2 is an enlarged plan view of one bead substrate of the metal gasket of FIG. 1 at reference numeral C.

3 is an enlarged plan view of the other bead substrate of the metal gasket of FIG. 1 at reference numeral C. FIG.

FIG. 4 is a cross-sectional view showing an example of the metal gasket of FIG. 1 taken along the line AA.

5 is a sectional view showing a second embodiment of the metal gasket according to the present invention and showing a portion corresponding to line AA of the metal gasket of FIG. 1. FIG.

6 is a cross-sectional view showing a third embodiment of the metal gasket according to the present invention and showing a portion corresponding to line AA of the metal gasket of FIG. 1. FIG.

7 is a sectional view showing a fourth embodiment of the metal gasket according to the present invention and showing a portion corresponding to line AA of the metal gasket of FIG. 1. FIG.

FIG. 8 is a sectional view showing a fifth embodiment of the metal gasket according to the present invention and showing a portion corresponding to line AA of the metal gasket of FIG. 1.

9 is a partial cross-sectional view showing a cross-sectional structure of a pair of bead substrates of the metal gasket of FIG.

[Explanation of symbols]

 1, 2 bead substrate 3, 4 bead 5, 6 stopper bead 7 hole 17 convex surface 23, 24, 25, 26 half bead

Claims (7)

[Claims] 1. A first bead substrate made of an elastic metal plate having first beads formed along parallel holes, and a second bead made of an elastic metal plate having second beads formed along parallel holes. A first substrate and a second bead facing each other; and
A first stopper bead is formed on the bead substrate along the hole on the hole side of the first bead protruding in the same direction as the first bead, and the first bead substrate has the first stopper bead on the second bead substrate.
A second stopper bead is formed along the hole on the hole side of the second bead protruding in the same direction as the stopper bead and in the direction opposite to the second bead, and the heights of the first and second stopper beads. Is a metal gasket formed to be lower than the height of the first and second beads. 2. The metal gasket according to claim 1, wherein the first stopper bead and the second stopper bead are separated from each other in a non-pressing free state. 3. The metal gasket according to claim 1, wherein the first stopper bead and the second stopper bead overlap with each other in a non-pressed free state. 4. The metal gasket according to claim 1, wherein a half bead extending toward the first bead substrate is formed between the second bead and the second stopper bead of the second bead substrate. . 5. A first half bead extending toward the second bead substrate is formed between the first bead of the first bead substrate and the first stopper bead, and the first bead substrate of the second bead substrate is formed. The metal gasket according to claim 1, wherein a second half bead extending toward the first bead substrate is formed between the second bead and the second stopper bead. 6. The first bead formed on the first bead substrate and the second bead formed on the second bead substrate are in contact with each other while protruding in opposite directions. The metal gasket described. 7. The first bead formed on the first bead substrate and the second bead formed on the second bead substrate extend in the same direction and overlap each other. The metal gasket described.