JPH03186668A - Metal gasket - Google Patents

Abstract

PURPOSE:To make selection possible in a suitable range with a spring constant of beads adjusted, even in the case of a small space between a through hole of a gasket and its edge side, by providing a small through hole between a flat part between the double beads and tilt surfaces on the peripheral side of the bead so as to adjust the spring constant of the bead. CONSTITUTION:Beads 4, 4', formed of tile surface 5, 5', are double formed in the periphery of a through hole 2 so as to surround this through hole, and a small through hole 7 is provided in a flat part 6 between the beads 4, 4' in the internal peripheral and peripheral sides. A spring constant of the bead in the intermediate part of a bolt insertion hole 3 is adjusted by the long and narrow small through hole 7, while a spring constant of the bead in the vicinity of the bolt insertion hole is adjusted by a hole 8. Accordingly, even in the case of the spring constant difficult to be adjusted in a desired range only by a conventional spring constant adjusting means without a space margin, the spring constant can be easily adjusted to the desired range.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The metal gasket of the present invention can be suitably used for sealing a flange connection of an exhaust gas pipe system of an automobile engine.

(Prior art) A flange connection between an exhaust manifold and an exhaust gas pipe of an engine such as an automobile, or a flange connection in an exhaust gas pipe system, such as a connection between an exhaust pipe and a catalytic converter, or an exhaust pipe and a muffler. Metal gaskets made of metal plates are partially used to seal the connections with the

These flange connections are usually made by welding a flange to the end of the exhaust gas pipe, so the plane accuracy (flatness) of the flange surface is poor due to thermal distortion caused by welding, and it is just a metal plate. It is difficult to ensure a sufficient seal against exhaust gas by simply holding the gasket between flanges and tightening it with bolts.For this reason, gaskets such as those disclosed in Japanese Patent Application Laid-Open No. 62-261755 have recently been used. This is a metal gasket in which beads are formed on a metal plate as shown in FIG. 6 (plan view) and FIG. 7 (cross-sectional view taken along line AA' in FIG. 6). That is, a metal plate 1 having a through hole 2 through which exhaust gas passes and a bolt insertion hole 3 is provided with a bead of soil consisting of inclined surfaces 5 and 5' and a bead 4' surrounding the through hole 2. It was formed. A single bead may be provided around the through hole 2, but usually a double bead is formed with the inclined surfaces 5 and 5' having opposite directions of inclination, as shown in the figure. There are many things to do. Also, although Figs. 6 and 7 show a metal gasket made of one metal plate, as shown in Fig. 8, two metal punches and 1' are stacked in opposite directions. Often.

When a metal plate with such a diagonal formed thereon, that is, a metal gasket, is held between the flanges and tightened with a bolt, the pressing force on the bead portion surrounding the through hole 2 becomes large, especially at the proximal end of the bead shown in FIG. and bead apex C
is strongly pressed against the flange surface, and the sealing performance against exhaust gas passing through the through hole 2 is enhanced.

In order to ensure good sealing over the entire periphery of the through hole 2 in a metal gasket having such a bead, the spring constant of the bead has already been adjusted as appropriate depending on the location. In other words, the tightening force or surface pressure acting on the metal gasket is different between the position N near the bolt insertion hole (Fig. 6) and the intermediate position M of the bolt insertion hole away from the bolt insertion hole (Fig. 6). In places where the tightening force is weak and the surface pressure is small, such as the middle position M of the bolt insertion hole, the spring constant of the bead is made small in order to improve the fit between the metal gasket and the flange surface. In addition, even in places where the bolt tightening force is large and the surface pressure is large, such as position N near the bolt insertion hole, if the bead spring constant is too large, the bolt tightening force will be consumed excessively near the bolt insertion hole. Since the tightening force is weaker in areas far from the bolt insertion hole, it is necessary to select it within an appropriate range.

The spring constant when the bead is pressed is determined by the height h and width t of the bead shown in Fig. 9. The larger the height h, the wider the width t.
The smaller the height h, the larger the width t, and therefore the smaller the angle θ, the smaller the bead spring constant becomes. . Further, in the case of double beads, the larger the interval W between the beads, the smaller the spring constant, and conversely, the smaller the interval W, the larger the spring constant.

(Problems to be Solved by the Present Invention) As mentioned above, in order to ensure sufficient sealing performance over the entire periphery of the hole through which exhaust gas passes, it is necessary to appropriately adjust the spring constant of the bead. The spring constant was adjusted by appropriately selecting the bead height, the bead width t, the angle θ, or the distance W between the double beads.

However, the dimensions of the metal gasket are determined by the flange dimensions of the flange connection part of the exhaust gas pipe system, and the distance between the through hole and the edge of the gasket is usually narrow, and the width of the bead or the distance W between the double beads is In many cases, it is not possible to select a large value for the metal gasket and the flange surface, so the spring constant of the bead in a place where the bolt tightening force, i.e. the surface pressure applied to the gasket, is small, such as near M in Figure 6, is adjusted so that the metal gasket and flange surface are compatible. There is a problem in that it is difficult to adjust the value within a desired range. For the same reason, the spring constant tends to become excessive near the bolt insertion hole, and excessive bolt tightening force is consumed near the bolt insertion hole, making it difficult to distribute the tightening force to the entire area around the hole 2. The problem was that it was easy to be inhibited.

In view of the above points, the present invention provides a new means for adjusting (reducing) the spring constant of the bead, and reduces the spring constant of the bead even when the distance between the gasket hole and the gasket edge is small. The purpose is to make it possible to select an appropriate range.

(Means for Solving the Problems) Similar to the conventional metal gasket described above, the metal gasket of the present invention is more effective than one or more metal plates each having a through hole through which exhaust gas passes and a bolt insertion hole. , a double bead consisting of an inclined surface is formed around the through hole of the metal plate so that the inclined directions of the inclined surfaces are opposite to each other.

Furthermore, in the metal gasket of the present invention, for the above-mentioned purpose, a small through hole is provided between the flat part between the double beads and the inclined surface on the outer peripheral side of the bead, thereby increasing the spring constant of the bead. This makes it possible to adjust (reduce) the

The small through hole may be a small hole provided in the flat part between the double beads and have an elongated shape along the circumferential direction of the through hole, or may be an oval or elliptical hole, as shown in the examples below. It may be formed as a group of shaped pores.

Adjustment of the bead spring constant using a small through hole provided in the flat part between the beads is generally done because the gap between the through hole and the edge of the gasket is the smallest and there is the least amount of space available, and it also works on the gasket. It is suitable for application to the bead in the middle part of the bolt insertion hole (M in FIG. 6) where the surface pressure is small. On the other hand, a small through hole may be provided over the bead's inclined surface and apex corner on the outer peripheral side of the double bead width, and the adjustment of the bead's spring constant using this small through hole is generally performed by inserting a bolt. It is suitable for application to the bead near the bolt insertion hole (N in FIG. 6) where there is a little more space than the middle part of the hole and where the surface pressure acting on the gasket is large. However, it goes without saying that these applications are not limited to the above. Furthermore, even when small through holes are provided across the slope and apex of the outer bead in a double bead, it is of course possible to provide a plurality of small holes instead of one small hole. .

(Function) In the metal gasket of the present invention, a small through hole is provided between the flat part between the double beads and the sloped surface on the outer peripheral side of the bead, so that the metal gasket of the present invention is held between the flanges. However, when tightened, the flat portion and the sloped surface of the bead bend more easily due to the pressing force than in the case where there are no small through holes, that is, the spring constant of the bead becomes smaller.

(Example) Examples of the metal gasket of the present invention are shown in FIGS. 1 to 5. FIG. 1 is a plan view of the metal gasket according to the present invention, and FIGS. It is a sectional view taken along the line AA' and the line BB'. FIG. 4 is a partially enlarged plan view of another embodiment of the invention, and FIG. 5 is a sectional view of still another embodiment of the invention.

In the figure, 1 and 1' are stainless steel (SUS301
-C5P), and is equipped with a through hole 2 through which exhaust gas passes and two bolt insertion holes 3. -4- and 4' are beads consisting of inclined surfaces 5 and 5', and the beads are formed in double layers around the through hole 2 so as to surround this.66 is the bead 4 on the inner circumferential side and the bead on the outer circumferential side. A small through hole 7 is provided in the flat portion 6 between the beads 4' of the bolt 4 and at a location in the middle of the bolt insertion hole. The width of the flat portion, ie the distance between the beads 4 and 4', is, for example, 6 m.

The small through hole is a long, arc-shaped hole that matches the shape of the flat portion 6, and has a width of, for example, 3 m and a length of, for example, 20 am. Reference numeral 8 indicates a hole provided inside the bolt insertion hole 3, and the liquid hole is located between the inclined surface 5' of the bead 4' on the outer peripheral side of the double bead, its apex corner C, and the outer side of the bead 4' on the outer peripheral side. It is provided across the flat surface 9, and moreover, it is provided so as to partially surround the bolt insertion hole 3. For example, the length of the hole is 2
The width is, for example, 6IIIl on the line connecting the center of the through hole 2 and the center of the bolt insertion hole 3, which is the narrowest. The reason why the hole 8 is provided inside the bolt insertion hole 3 so as to partially surround the bolt insertion hole 3 is to reduce the conduction of the heat of the exhaust gas to the bolt through the metal gasket. In this embodiment, the spring constant of the bead in the middle part of the bolt insertion hole 3 is adjusted by the small elongated through hole 7 provided in the flat part 6 between the double inner and outer bead soils and 4'. 68, the spring constant of the bead in the vicinity of the bolt insertion hole is am.

FIG. 4 shows an embodiment in which small through holes are provided in the flat part 6 between the double bead soil and 4' as a group of oval holes 71, 72, 73, 74 and 75. FIG. 5 shows a metal gasket according to the present invention in which an intermediate metal plate 10 is sandwiched between the metal plate 1 and the workpiece. Metal gasket odorIncreasing the number of metal plates has the effect of increasing the restoring force of the gasket.

(Effects of the Invention) As mentioned above, the metal gasket of the present invention can be used as a means for adjusting the spring constant of the bead, in addition to the conventional means of adjusting the bead height, bead width, and interval between beads. Small through holes are provided between the flat part between the double beads and the sloped surface on the outer peripheral side of the beads, and the spring constant of the bead can also be adjusted (reduced) by these small through holes, so the space can be saved. Even in cases where it is difficult to adjust the spring constant to the desired range using conventional spring constant adjustment means due to lack of margin, it can be easily adjusted to the desired range, and this has a significant effect on the design of metal gaskets. be.

[Brief explanation of drawings]

FIG. 1 is a plan view of a metal gasket according to the present invention, and FIGS. 2 and 3 are lines A-A' and B-B in FIG. 1, respectively.
' is a cross-sectional view of the line. FIG. 4 is a partially enlarged plan view of another embodiment of the invention, and FIG. 5 is a sectional view of still another embodiment of the invention. 6 and 7 are a plan view and a sectional view (A-A'l in FIG. 6) of a conventional metal gasket. FIG. 8 is a sectional view of another example of a conventional metal gasket; Figure 9 is an explanatory diagram of the bead. (Explanation of symbols) 1 and 1'...Metal plate, 2...Through hole, 3...
・Bolt insertion hole, ± and soil 2...bead, 5
and 5'... Sloped surface, 6... Flat part between beads, 7... Small through hole, 8... Hole, 9... Outer periphery flat part, 1°... Intermediate metal plate, 71 ~75...
Oblong hole, b...base end of bead, apex corner of bead for c. -And more-

Claims (1)

[Claims] (1) In a metal gasket consisting of one or more metal plates having a through hole through which a fluid passes and a bolt insertion hole, a bead consisting of an inclined surface surrounds the through hole of the metal plate. are formed double so that the slope directions of the slopes are opposite to each other, and a groove for adjusting the spring constant of the bead is formed between the flat part between the double beads and the slope on the outer peripheral side of the bead. A metal gasket characterized by having small through holes.