JPH0495669A - Metal-made cylinder head gasket - Google Patents

Abstract

PURPOSE:To obtain a metal-made cylinder head gasket, increasing the compression quantity of a bead and having an excellent followable property to a gap change, by making constitution in which bead top parts are arranged in eccentric positions, and thereby the fellow tilted surfaces having small inclination are partially overlapped. CONSTITUTION:A first bead 24 having a mountain-like shape is formed on a first elastic substrate 21 so as to annularly surround a combustion chamber 23, and similarly a second bead 25 is formed on a second elastic substrate 22. The mountain-like shapes of each bead 24 and 25 are composed so that each of bead top parts 24a and 25a is located on a position eccentric to the middle position in the width direction of the beads 24 and 25. By this constitution, tilted surfaces 24b and 25b having small inclination and tilted surfaces 24c and 25c having large inclination are formed on the beads 24 and 25, and the fellow tilted surfaces 24b and 25b having small inclination of each of the beads of 24 and 25 are composed so as to be partially overlapped. This causes a total compression quantity to have more than one bead compression quantity, allowing improvement of a gap followable property.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a metal cylinder head gasket, and more particularly to a metal cylinder head gasket having a structure formed by laminating two elastic substrates.

[Conventional technology]

Generally, a metal cylinder head gasket (hereinafter simply referred to as metal gasket) is disposed between the cylinder block and the cylinder head to prevent leakage of gas generated within the combustion chamber. Various structures have been proposed for this metal gasket, one of which is two-piece (
There is a metal gasket that has a structure in which a bead is formed on the periphery of the combustion chamber hole and laminated with elastic substrates (or more).

Conventional metal gaskets having a structure in which two elastic substrates are laminated include those shown in Japanese Unexamined Patent Publication No. 64-6563 and Japanese Utility Model Application No. 63-84462.

FIG. 8 is a schematic diagram of a metal gasket 1 disclosed in Japanese Patent Application Laid-Open No. 64-6563. This metal gasket 1
correspond to the bead top 3a of the first elastic metal substrate 2, the heat top 5a of the second elastic metal substrate 4, and the root parts of the beads 3 and 5 formed on the other elastic metal substrates 2.4, respectively. It had a similar structure. Therefore, each elastic metal substrate 2,
When the beads 4 are assembled, the beads 3 and 5 have a structure in which they are arranged side by side.

FIG. 9 is a schematic diagram of a metal gasket 6 shown in Japanese Utility Model Application No. 63-84462, or this metal gasket 6 also has a structure similar to the metal gasket 1 described above, but each bead 7 The spacing dimension is set to be as wide as .8.

On the other hand, as shown in FIG. 1O, each elastic metal substrate 9.
Bead formed in IO)”II, bead top 11 of 12
There was also a metal gasket [3] with a structure in which a and 12a were arranged facing each other so as to coincide with each other.

[Problem to be solved by the invention]

However, since the metal gaskets 1 and 6 shown in FIGS. 8 and 9 have a structure in which the beads 3 and 5 and the beads 7.8 are arranged in parallel, the metal gaskets are placed between the cylinder block and the cylinder head. l.

The amount of compression when 6 is placed is beat 35.7
．． 8 (indicated by t in each figure), and this compression amount becomes small. For this reason, there was a problem that the elastic deformation of the beats 3, 5, and 7.8 could not follow the change in the gap between the cylinder block and the cylinder head, resulting in poor sealing performance.

In addition, in order to achieve a predetermined sealing performance with the metal gaskets 1 and 6 having the above configuration, the seal width must be designed to be large (at least 1 part of the beat width).
．． 5 times) and cannot be applied to engines with narrow seal widths.

On the other hand, in the metal gasket 13 shown in FIG. 1O, each elastic metal substrate 9. If a misalignment occurs between the IOs, the bead 1"11.12 will be distorted and compressed, resulting in uneven surface pressure and poor sealing performance. Also, with the metal gasket 13 of this configuration, , beat 11.1
Since the structure is arranged in two vertical stages, the amount of compression will be large, or since there is nothing to suppress the compressive deformation of each bead 11 and 12, deformation equivalent to the tightening load of the cylinder block and cylinder head will occur. Live. For this reason, each beat 11.
There was a problem in that the stress generated in heat 12 was high, and there was a risk that cracks would occur in each heat 11 and heat 12.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a metal cylinder head gasket that can increase the amount of bead compression and has good followability to changes in the gap between the cylinder block and the cylinder head. purpose.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a first tube having a chevron-shaped cross section and formed so as to annularly surround the combustion chamber hole.
a first elastic substrate provided with a bead, and a second elastic substrate provided with a second bead, which also has a chevron-shaped cross section and is formed to annularly surround the combustion chamber hole; In a metal cylinder head gasket having a structure in which first and second elastic substrates are laminated so that the first and second beads face each other, the bead tops having the first and second beats are The first and second
It is characterized by a structure in which the sloped surfaces formed on the bead with small slopes partially overlap each other.

[Function] According to the metal cylinder head gasket having the above structure, the top of the bead is located at an eccentric position, and the slopes formed by this are in contact with each other, so the width of the bead does not have to be particularly large. Even if the first and second elastic substrates are misaligned, each bead will not be distorted and compressed.

Further, since the beads formed on the first and second elastic substrates partially overlap, the total amount of compression can be greater than the amount of compression of one bead, so it is possible to improve the gap followability.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a metal gasket 20 (
FIG. 2 is a partial vertical cross-sectional view of a metal gasket. In the figure, 21 is a first elastic substrate, and 22 is a second elastic substrate. These first and second elastic substrates 2
Both substrates 1 and 22 are made of stainless steel spring plates, and the metal gasket 20 is constructed by overlapping both substrates 21 and 22. Note that 23 in the figure indicates a combustion chamber hole.

Further, FIG. 2 shows a plan view of the metal gasket 20 (the above-mentioned FIG. 1 is a sectional view taken along the line A-A in FIG. 2). As shown in the figure, the metal gasket 20 has bolt holes 26 through which bolts are inserted when the metal gasket 20 is installed between the cylinder block and the cylinder head.
．． Cooling water hole 27 for passing cooling water. Lubricating oil hole 2 for passing lubricating oil
8 degrees, and combustion chamber holes 23 and the like are formed. Furthermore, beads 24 and 25 are formed to surround the combustion chamber hole 23.

Returning to FIG. 1 again, explanation will be given. A chevron-shaped first bead 24 is formed on the first elastic substrate 21 so as to annularly surround the combustion chamber hole 23 . In addition, the second elastic substrate 22
Similarly, a second chevron-shaped bead 25 is formed to annularly surround the combustion chamber hole 23. The first and second elastic substrates 21 and 22 are overlapped to form one metal gasket 20, as shown in the figure.

In this embodiment, the first and second beads 24,25 have vertically symmetrical shapes. Moreover, the chevron shape of each bead 24, 25 is each bead top 24a.

25a is located at a position eccentric to the center position of the bead 24.25 in the width direction.

That is, if the width dimension of the beads 24, 25 is W, and the dimension from one edge of the beads 24, 25 (the part indicated by the arrow X in the figure) to the bead tops 24a, 25a is W, then w
The chevron shape of beats 24 and 25 is configured so that <(W/2).

With this configuration, the bead 24.25 is formed with inclined surfaces 24b, 25b having a small inclination and inclined surfaces 24c, 25c having a large inclination.

As described above, the metal gasket 20 is constructed by overlapping the first and second elastic substrates 21.22, but at this time, the small inclined surfaces 24b and 25b of each bead 24.25 overlap each other. Each elastic substrate 21.
22 are superimposed. Further, the inclined surfaces 24b and 25b are configured so that they do not overlap entirely, but partially overlap. Therefore, if the length of the overlapping portion of the inclined surfaces 24b and 25b (hereinafter referred to as the overlapping portion) is d, then d<(W-W).

Furthermore, by configuring the inclined surfaces 24b and 25b to partially overlap each other, the total amount of compression of the metal gasket 20 (this total amount of compression corresponds to the distance H between the elastic substrates 21 and 22) is It is larger than each height dimension of the bead 24°25, and the height dimension 2X when the bead tops 24a and 25a are aligned (as shown in Figure 1O)
It becomes smaller than h.

Next, the function of the metal gasket 2o having the above structure will be explained below.

As described above, each of the bead tops 24a, 25a is located at an eccentric position with respect to the center position in the width direction of the beads 24, 25, and the sloped surfaces 24b, 25b having a small slope are configured to partially overlap. . Therefore, even if the bead radius W is not particularly large, it is possible to ensure a large overlapping portion d of each bead 24, 25, and each elastic substrate 21.
Even if the beads 22 are misaligned, each bead 24, 25 will not be distorted. Therefore, the surface pressure generated at the positions of the beads 24 and 25 can be made uniform and the sealing performance can be improved.

Further, the total compression amount H of the metal gasket 20 is
．． Because it is larger than the height dimension of each one of 25,
It is possible to improve rWI gap followability. That is, since the metal gasket 20 deforms over the total compression amount H,
Even if the gap created between the cylinder block and the cylinder head changes significantly due to temperature changes, the metal gasket 20 deforms accordingly, so that the sealing performance can also be improved.

In Fig. 3(A), a metal gasket 2 is attached between the cylinder block 29 and the cylinder head 30 at the front when tightening the bolts.
0 indicates an interposed state.

Further, FIG. 3(B) shows the metal gasket 20 after bolt tightening, together with the surface pressure distribution. The metal gasket 20 has a bead top 24a.

25a has a special eccentric shape.
), during compression, each bead 24,
25, a plurality of fine beads formed by compression deform while overlapping each other.

Therefore, the beads 24 and 25 suppress each other's compression, and the contact area between the cylinder block 29 and the cylinder head 30 also increases to equalize the surface pressure, thereby improving sealing performance.

On the other hand, Fig. 4 shows that the metal gasket 20 is tightened at times.
shows the direction of the load applied to the

In the same figure, F is the load of gasket tightening, and f
, is the force of each bead 24, 25 trying to engage with each other,
Further, f indicates a vertical surface pressure applied perpendicularly to each bead 24, 25. As mentioned above, the heats 24 and 25 have a structure in which the inclined surfaces 24b and 25b partially overlap, and therefore, as shown in the figure, the load F when tightening the gasket is applied in the overlapping part. . Of this component force,
f.

is a force that acts to engage each beat 24, 25, and this force fh can prevent the occurrence of misalignment of each elastic substrate 21 and 22.

Further, the dimensions of the overlapping portion d of each bead 24, 25 do not need to be the same around the combustion chamber hole 23, and can be changed depending on the location. It is possible to equalize the surface pressure of the beads 24, 25 in the surrounding area. This will be explained using FIGS. 5 to 7.

As is well known, the surface pressure of a metal gasket is large near the bolt tightening position, and decreases as it moves away from the bolt tightening position.

Therefore, if the dimensions of the overlapping portion d of the beads 24 and 25 are the same over the entire circumference, the surface pressure distribution will be as shown in FIG. 7(A). In this configuration, since the surface pressure at a position distant from the bolt tightening position is small, there is a risk of gas leakage from this part.

Therefore, by changing the dimensions of the overlapping part d of the beads 24 and 25 between a position close to the bolt tightening and a position distant from this, and changing the substantial spring constant of the beads 24 and 25, the surface pressure is uniform. It is also possible to adopt a configuration that aims to achieve this.

Specifically, as the bolt tightening shown by the arrow A-A in FIG. , the surface pressure is set to be large by substantially increasing the spring constant. In addition, when tightening the bolts shown by the arrow B-B in FIG. 5, the dimension of the overlapping portion of the beats 24 and 25 is set to a large value d4 as shown in FIG. By decreasing the constant, the surface pressure is set to be low. With this configuration, the surface pressure near the combustion chamber hole 23 of each beat 24.25 is made uniform over the entire circumference as shown in FIG. 7(B), and the arrangement of each heat 24.25 The sealing performance can also be made uniform over the entire location.

Note that in the above embodiment, the first and second elastic substrates 21.
The shape of each heat 24.25 formed in 22 may be symmetrical on the top and bottom, but it is not limited to this, and may be asymmetrical on the top and bottom.By appropriately arranging this asymmetrical portion, It is possible to locally provide stronger or weaker sealing properties, and it is also possible to realize a more appropriate seal that corresponds to the sealing area.

〔Effect of the invention〕

As described above, according to the present invention, the overlapping area of the first and second beads can be increased without making the bead width particularly large, so that misalignment between the first and second elastic substrates can be prevented. However, each bead will not be distorted or compressed.

Furthermore, since the beads formed on the first and second elastic substrates partially overlap, the total amount of compression can be greater than the amount of compression of one bead, so it is possible to improve the gap followability.

[Brief explanation of drawings]

Fig. 1 is a partial longitudinal cross-sectional view of a metal gasket which is an embodiment of the present invention, Fig. 2 is a plan view of a metal gasket which is an embodiment of the invention, and Fig. 3 is a partial longitudinal sectional view of a metal gasket which is an embodiment of the present invention. Figure 4 shows the direction of the load applied to the metal gasket during tightening. Figures 5 to 7 show the surface pressure of the bead around the combustion chamber hole. FIGS. 8 to 10 are diagrams for explaining the structure of a conventional metal gasket. 20... Metal gasket, 2I... First elastic substrate, 22... Second elastic substrate, 23... Combustion chamber hole, 2
4... first bead, 24a, 25a... bead top, 24b, 25b... inclined surface, 25... second bead. Patent applicant: Toyota Motor Corporation Figure 1 Figure 3 (A) 1 Figure 2 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Scope of Claims] A first elastic substrate having a chevron-shaped cross section and provided with a first bead formed to annularly surround a combustion chamber hole; a second elastic substrate provided with a second bead formed to annularly surround the first and second elastic substrates, and the first and second elastic substrates are stacked so that the first and second beads face each other. In the metal cylinder head gasket, the bead tops of the first and second beads are arranged eccentrically with respect to the center position of each bead in the width direction, and the bead tops are made eccentric. A metal cylinder head gasket characterized in that the first and second beads have sloped surfaces with small slopes that partially overlap each other.