JPH0488265A - Metal gasket - Google Patents

Abstract

PURPOSE:To improve the sealing function of an outer peripheral bead and improve reliability by setting the spring constant of a bead formed at the outer peripheral edge part to be relatively smaller than that at the separated part, at the part where the bead approaches within a prescribed distance. CONSTITUTION:The height H of an outer peripheral bead 18 is set lower than the height H2 of other bead 17 at the part where other bead 17 in proximity exists, and set higher than the height H2 at the part where other bead 17 is close, at the part where other bead 17 in proximity does not exist, and the spring constant of the outer peripheral bead 18 is set small at the part where other bead 17 in proximity exists, and set large at the part where other bead 17 does not exist. Since the spring constant of the outer peripheral bead 18 can be varied according to the part where other bead 17 is close or not, the surface pressure due to the outer peripheral bead 18 can be made nearly equal at all parts independently of the existence of other bead 17 in proximity, and the sealing function of the outer peripheral bead 18 can be improved in comparison with that in the conventional.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a metal gasket, and in particular to a metal gasket on the joint surface between a cylinder head and a cylinder block in order to prevent leakage of combustion gas, cooling water, lubricating oil, etc. This invention relates to a metal gasket for internal combustion engines.

[Conventional technology]

Conventionally, as a metal gasket for internal combustion engines, fluid vent holes are drilled in a thin metal elastic substrate corresponding to the fluid passages for combustion gas, cooling water, lubricating oil, etc. between the cylinder head and cylinder block. A metal gasket is known in which a bead is formed on the periphery of an appropriate fluid vent hole and a bead is also formed on the outer periphery of the substrate (Japanese Utility Model Publication No. 86459/1989). There is also known a metal gasket in which a bead is formed on each of the periphery of the fluid vent hole and the periphery of the bolt hole (Japanese Utility Model Publication No. 59-188351).

In these metal gaskets, there are areas where separate beads are close to each other, and areas where the beads are separated by a predetermined distance or more and can therefore be considered to exist independently.

[Problem to be solved by the invention]

However, with conventional metal gaskets, no consideration is given to whether or not the beads are close to other beads, and because the bead height is constant at all locations, it is difficult to determine whether the beads are separate or close to each other. The spring stiffness of the part where the bead is present is higher than that of the part where the bead can be considered to exist independently. For this reason, in conventional metal gaskets, the surface pressure differs depending on whether the bead is close to another bead, and the sealing performance deteriorates in areas where the bead can be considered to exist independently, resulting in fluid leakage. There is a problem that leakage is likely to occur.

The present invention has been made in view of the above points, and provides a metal gasket that solves the above problems by setting the spring constant of a bead depending on whether or not a bead is close to another bead. With the goal.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a metal gasket in which a bead is formed to surround each of a plurality of fluid extraction holes and a plurality of bolt holes, and a bead is formed along the outer peripheral edge of the metal elastic substrate. In areas where the bead formed along the outer periphery of the metal elastic substrate and another bead are close to each other within a predetermined distance, the outer periphery of the metal elastic substrate The spring constant of the bead formed along the section is set relatively small.

[Effect]

In areas where the bead formed along the outer periphery of the substrate and other beads are close to each other within a predetermined distance, the elastic restoring forces of both beads are added, so the surface area is lower than that of other independent areas. Pressure is high. Therefore, in the present invention, among the respective portions of the bead formed along the outer peripheral edge of the substrate, the spring constant of the adjacent portion where another bead is within a predetermined distance is relatively lower than that of the other portion. Because it is set to small,
The surface pressure at the above-mentioned adjacent portion can be made approximately equal to the surface pressure at the pond portion.

〔Example〕

FIG. 1 is a sectional view of a main part of an embodiment of the present invention, FIG. 2 is a partial plan view of an embodiment of the present invention, and FIG. 3 is a partial sectional perspective view of FIG. 2. In each figure, the same components are given the same reference numerals.

In FIG. 2, lO is a metal elastic substrate made of, for example, a stainless steel plate, and the combustion chamber hole 11. Cooling water hole 12. A lubricating oil hole 13 and a bolt hole 14 are respectively drilled. The combustion chamber hole 11 is formed as a vent hole for combustion gas corresponding to the combustion chamber on the cylinder block side, and the cooling water hole 12 and the lubricating oil hole 13 are provided as a cooling water passage between the cylinder block and the cylinder head, and a lubricating oil passage, respectively. Holes are bored for cooling water and lubricating oil in correspondence with the respective passages. The bolt hole 14 is arranged around the combustion chamber hole 11.

As shown in FIG. 3, a bead 15 having a semicircular arc cross section is formed at the peripheral edge of the combustion chamber hole 11, and the apex 1 of the bead 15
A shim ring 20 made of, for example, a stainless steel plate is heat-fused to a flat portion between the combustion chamber hole 5a and the end of the combustion chamber hole 11 by laser welding. In FIG. 3, 21 indicates a weld line created by laser welding.

In addition, as shown in Figure 2, among the bolt holes 14, the bolt holes 14 that are not adjacent to the Miyabi holes (in Figure 2, the two on the upper left and lower left)
A bead 16 is formed along the periphery of the bolt hole 1 adjacent to the lubricating oil hole 13.
4, a bead 17 is formed to surround the lubricating oil hole 13 and the bolt hole 14, respectively. Furthermore, a bead 18 (hereinafter referred to as an outer peripheral bead for convenience) is formed roughly along the outer peripheral edge of the substrate IO so as to surround all the above-mentioned companies 11 to 14 and beads 16 and 17 on the substrate IO. ing. This outer bead 18 is similar to the other bead 16.1.
It has a part close to 7 and a part away from other beads.

Here, in FIG. 2, a cross section taken along the line A-A of a portion where the outer peripheral bead 18 is separated from other beads is as shown in FIG. It can be seen that it is constituted by an inclined section having a height H and a substantially linear cross section with respect to the bottom surface of the bottom surface. Since this outer peripheral bead 18 corresponds to the half slope of the bead 15 having a semicircular arc cross section, it is called a half bead, and the bead 15 is called a full bead. Note that the beads 16 and 1 described above
7 is a half bead.

Further, in FIG. 2, a cross section taken along line B-B of a portion where the outer peripheral bead 18 is close to another bead is as shown in FIG. 1(B). That is, in FIG. 1(B), the outer circumferential bead 18, which is an inclined portion having a substantially linear cross section and having a height Hl, is connected to the bead 17 via the flat portion 25 with respect to the bottom surface of the substrate 10.

The bead 17 is a half bead formed by an inclined portion having a height h and a substantially linear cross section relative to the bottom surface of the substrate 10 . The distances (widths) of the beads 18 and 17 on a plane parallel to the bottom surface of the substrate 10 are W, respectively, as shown in FIG. 1(B).
It is w.

Here, each of the above-mentioned widths W and W is appropriately set according to the specifications, such as the elastic restoring force of the substrate 10 and the tightening torque between the cylinder block and the cylinder head. According to the outer peripheral bead 18 and other beads 17
If the distance between the two beads is less than 5 times the radius W of the outer bead 18, it will affect the elastic restoring force of the outer bead 18 or the elastic restoring force of other beads 17, making the surface pressure uneven when using a metal gasket. It will be.

Therefore, in this embodiment, within the range of L≦5W, (1) the height H3 of the portion of the outer peripheral bead I8 where another bead is close to the outer peripheral bead 18 is set to the range of L>5W in FIG. 1(A) described above. The height Hl of a portion where a certain outer peripheral bead 18 can be considered to exist independently is smaller than the height Hl, and (2) the height h of other adjacent beads 17 or less. Other nearby beads 1
The reason why the height H2 of the outer circumferential bead 18 is made lower than the height h of the bead 7 is to place emphasis on the surface pressure of the other bead 17 on the inside and to prevent leakage of lubricating oil as much as possible.

As described above, according to the present embodiment, the height of the outer peripheral bead 18 is made lower than the height of the other bead in a region where there is another bead in the vicinity, and The spring constant of the outer peripheral bead 18 is made smaller in areas where other beads are present, by making the height of the outer bead 18 higher in areas where beads are not present than in areas where other beads are adjacent, and where other beads are not present. It is large in some parts.

The metal gasket of this embodiment is interposed between a cylinder block and a cylinder head, and is used by fastening the cylinder block and cylinder head together through bolt holes 14. As a result, the metal gasket is compressed and deformed until its elastic restoring force balances the bolt tightening torque, and the metal gasket is brought into close contact with the cylinder block and cylinder head to perform a sealing function.

Here, among the beads, the highest pressure acts on the bead 15 surrounding the combustion chamber hole 11, so the bead 15 has a full bead structure as shown in FIG. 3, and the other half beads 16 to 18 In comparison, the spring constant is the largest.

Furthermore, in this embodiment, as described above, the spring constant of the outer peripheral bead 18 is varied depending on whether or not other beads are adjacent to each other. Regardless of the presence or absence of beads, all parts can be made approximately uniform. Therefore, in this example,
The sealing function of the outer bead can be improved compared to the conventional method.

It should be noted that the present invention is not limited to the above-mentioned embodiments. For example, as a means for varying the spring constant of the outer peripheral bead 18, the easiest way to manufacture it is to vary the height, but the present invention is not limited to this. , width, etc. may be made variable. Further, the outer peripheral bead 18 is not limited to a half bead.

〔Effect of the invention〕

As described above, according to the present invention, the spring constant of the outer peripheral bead formed along the outer peripheral edge of the substrate is varied depending on whether or not another bead is close to the outer peripheral bead. By making the contact pressure at the part close to the bead almost equal to the contact pressure at the independent part, the sealing function of the outer bead can be improved compared to conventional products, which contributes to improving the reliability of metal gaskets. It has features such as being large.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of an embodiment of the present invention, FIG. 2 is a partial plan view of an embodiment of the invention, and FIG. 3 is a partial sectional perspective view of FIG. 2. DESCRIPTION OF SYMBOLS 10... Board, 11... Combustion chamber hole, 12... Cooling water hole, 13... Lubricating oil hole, 14... Bolt hole, 17
... Bead, 18... Outer circumference bead. 15゜6゜

Claims (1)

[Scope of Claims] A plurality of fluid vent holes and bolt holes are formed in a metal elastic substrate, and beads surrounding the plurality of fluid vent holes and bolt holes, respectively, and along the outer peripheral edge of the metal elastic substrate. In a metal gasket in which a bead is formed, in a region where the bead formed along the outer peripheral edge of the metal elastic substrate and another bead are close to each other within a predetermined distance, the bead is separated by a distance greater than the predetermined distance. A metal gasket characterized in that the spring constant of the bead formed along the outer peripheral edge of the metal elastic substrate is set to be relatively small compared to the other parts.