JPS59229037A - Gasket for exhaust manifold - Google Patents

Abstract

PURPOSE:To prevent the permanent set of a gasket used for an exhaust manifold from occurring as well as to secure sufficient effective clamping pressure, by solidifying a body composed of a metal plate and a hollow ring composed of a metal being arranged in a gas passing hole part as one body with a metallic grommet. CONSTITUTION:A body 27 consisting of aluminum coating steel plates 28, 29, 30 and 31 being overlapped to each other is provided with a gas passing hole 32 and a bolt hole 33. At this gas passing hole 32, a hollow ring 34 composed of a metal of stainless steel or the like is arranged. A metallic grommet 35 composed of stainless steel or the like is attached to the ring 34 and the body 27 each, and with this constitution, the body 27 and the grommet 35 are solidified in one.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a gasket for an exhaust manifold that is installed at a joint between a cylinder head and an exhaust manifold of an internal combustion engine.

[Prior art]

FIG. 1 shows an example of how the exhaust manifold gasket is installed, and is attached to the joint between the end wall around the exhaust boat 2 of the cylinder head 1 and the 7 flange portion 4 of the exhaust manifold 3. An exhaust manifold gasket 5 is interposed to prevent leakage of high-temperature exhaust gas.

Now, in recent years, engines have been trending towards higher horsepower and higher rotation speeds, and this trend has led to an increase in combustion pressure and an increase in heat load. At the same time, in recent years, there has been a trend toward lighter engines, and this trend has led to a decrease in the rigidity of the cylinder head 1.

As described above, as the thermal load applied to the cylinder head 1 increases, the exhaust manifold 3 connected to the cylinder head 1 is also simultaneously subjected to a large thermal load. Manifold tightening bolt 6 that connects the exhaust manifold 3 to the head 1
In general, the number of exhaust manifolds is relatively small, 2 to 3, and as the engines become lighter,
Thermal deformation of the exhaust manifold 3 is also extremely large due to reasons such as the fact that the rigidity of the exhaust manifold 3 is also low.

Furthermore, the thermal deformation of the exhaust manifold 3 described above includes not only static components but also many dynamic components that make cyclic movements (the broken line 3' in Figure 1 indicates the exhaust gas). Thermal deformation of manifold 3, h indicates the amount of deformation, respectively)
. For this reason, in recent years, the joint between the cylinder head 1 and the exhaust manifold 3 has become an environment where gas leaks are very likely to occur.

Moreover, if the tightening load of the tightening bolts 6 is too large, it will limit the thermal expansion of the exhaust manifold 3, which will cause cracks to occur in the exhaust manifold 3, which has low rigidity, and further gas leakage. There is even a danger that it will develop into

Under such harsh environments, exhaust manifold gaskets are required to have the following physical properties.

(a) Even if the bolt tightening force is reduced, sufficient effective tightening pressure can be obtained to maintain a gas seal.

(b) It has a large ability to absorb thermal deformation and structural deformation (deformation other than thermal deformation) of the flange portion of the exhaust manifold.

(c) It also has a large ability to absorb cyclic movements due to thermal deformation and structural deformation of the flange portion of the exhaust manifold.

(d) Less deterioration of properties such as fatigue (plastic deformation).

However, as will be explained next, conventional general manifold gaskets cannot satisfy the above-mentioned required physical properties, and it has become difficult to maintain a good gas seal.

FIGS. 2 and 3 show a gasket for an exhaust manifold of a type that has been used in large quantities in the past. A sheet-like compressible fiber material 9 is coated on both sides of a steel plate 8 with claws 7 raised on both sides. The crimped material is punched out in the shape of the seven flange portions of the exhaust manifold to form the main body 10,
And around the gas passage hole 911, the main body 10
A metal grommet 12 is attached to the metal grommet 12.

This gasket receives compressive stress at the metal grommet 12 and uses the compressive elasticity of the main body 10 to perform gas sealing, but the contact between the grommet 12 and the flange of the cylinder head and exhaust manifold is surface. Since the contact area becomes large, it is difficult to obtain sufficient effective tightening pressure with a small bolt tightening force.

Also, the temperature of the exhaust manifold joint is 600 to 700.
Since the compressible raIlI material 9 is generally composed of a mixture of asbestos and rubber, the thermal properties deteriorate significantly, and the main body 10 exhibits a sagging phenomenon. - This often resulted in gas leakage (curve A in Figure 9 shows the relationship between the tightening time and the amount of sagging of this gasket).

Curve A in Figure 8 shows the compression/strain curve of this gasket. On the other hand, the broken line shows the restoration curve, that is, the relationship between compressive stress and compressibility when compressive stress is decreased.) As is clear from this curve A, the compressive stress The amount of compression when receiving is relatively small,
The ability to absorb thermal and structural deformation of the exhaust manifold was poor.

FIG. 4 shows another example of a conventional exhaust manifold gasket, in which the main body 13 is made of a plurality of overlapping steel plates, a wiring 16 is arranged in the gas passage μ hole 14, and the wiring 16 and the main body are A metal grommet 15 is attached to 13 and 13.

In this gasket, due to the presence of the wiring 16,
Since the grommet 15 can be in line contact with the cylinder head and the flange portion of the exhaust manifold, a sufficient effective tightening pressure of 1η can be achieved even if the bolt tightening force is small.

In addition, since the main body 13 has a metal plate laminate structure with excellent heat resistance, the main body 13 does not exhibit a sticky phenomenon due to deterioration of thermal characteristics as in the case of the conventional gasket shown in FIG. Curve B in FIG. 9 shows the relationship between the tightening time of the gasket and the amount of settling.

However, the stress-strain curve of this gasket is shown by curve B in Figure 8, and as is clear from this, the amount of compression is small when subjected to compressive stress, and it absorbs thermal and structural deformation of the exhaust manifold. The drawback was that it was impossible.

FIG. 5 shows still another example of the conventional gasket, in which metal plates 19.20 are stacked on both sides of the metal plate 17.18, and around the gas passage hole 21, the metal plates 19.20
Bead portions 22 and 23 are provided on each side, and metal grommets 24 are attached to the bead portions 22 and 23, respectively.

In this gasket, due to the presence of the bead portions 22 and 23, the contact between the grommet 24 and the flange portion of the cylinder head and exhaust manifold can be made into a line contact, so even if the bolt tightening force is small, it is still sufficient. Effective tightening pressure can be obtained.

In addition, due to the presence of the bead portions 22 and 23, the amount of compression when compressive stress is applied is large (the compressive stress-strain curve of this gasket is as shown in curve C in Figure 8), and the exhaust manifold undergoes large thermal deformation. and an initial ability to absorb structural deformations.

However, as seen in the restoring curve part (broken line part) of curve C, the rebound resilience is weak, so it lacks the ability to absorb the cyclic movement of the thermal deformation and structural deformation of the flange part of the exhaust manifold. , and bead part 2
Since there is a space 25.26 between the metal plate 18 and the bead 22.23, the bead portion 22.23 becomes more prone to wear out as the operation progresses, resulting in gas leakage (as shown in Fig. 9). Curve C shows the relationship between the tightening time of this gasket and the amount of settling).

[Purpose of the invention]

The present invention was made in order to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a gasket for an exhaust manifold that fully satisfies all of the above-mentioned necessary physical properties.

[Structure of the invention]

The gasket for an exhaust manifold according to the present invention includes a main body made of a metal plate, a hollow ring made of metal arranged in a gas passage hole, and attached to the main body and the ring, so that the main body and the ring are integrated. It has a metal grommet.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on embodiments shown in the drawings.

FIGS. 6 and 7 show an embodiment of the present invention, in which the main body 27 consists of aluminized steel plates 28.2 stacked on top of each other.
Consists of 9.30.31. This main body 27 is provided with gas passage holes 32 and bolt holes 33. A hollow ring 34 made of metal such as stainless steel is disposed in the gas passage hole 32 . A metal grommet 35 made of stainless steel or the like is attached to the ring 34 and the main body 27, so that the main body 27 and the grommet 35 are integrated.

In these gaskets 1 to 1, the presence of the ring 34 causes the grommet 35 to come into line contact with the cylinder head and the 7 ring portion of the exhaust manifold, which reduces the contact area, and since the ring 34 is hollow, the exhaust gas Exhaust gas passing through the passage hole 32 (usually its temperature is 60°C)
When heated at a temperature of about 0 to 700°C, it exhibits large thermal expansion and increases the contact pressure between the grommet 35 and the cylinder head and the 7th ring part of the exhaust manifold, thereby increasing the tightening force of the bolt. Even if it is made small, sufficient effective tightening pressure can be obtained.

In addition, since the ring 34 is hollow, the amount of compression when receiving compressive stress is large (the curved line in FIG. 8 indicates the compressive stress-strain curve of this gasket), so the flange of the exhaust manifold is heated. Great ability to absorb deformation and structural deformation.

In addition, since the ring 34 is hollow, it has high repulsion resiliency to begin with, and the repulsion resiliency is further increased by the thermal expansion effect, so it absorbs the cyclic movement of the thermal deformation and structural deformation of the flange portion of the exhaust manifold. The ability to do so is also great, and the occurrence of sealing gisep is greatly reduced.

In addition, as mentioned above, the ring 34 has a high rebound resilience, so there is little wear and tear over the course of operation, and a stable gas seal can be maintained for a long period of time. (shows the relationship with the amount of settling).

Also, the main body 27. Since both the ring 34 and the grommet 35 are made of metal, they have excellent heat resistance, and there is no sagging phenomenon due to deterioration of thermal characteristics.

In the above embodiment, the main body 27 is made of a plurality of metal plates, but in the present invention, the main body may be made of a single metal plate.

(Effects of the Invention) As described above, the exhaust manifold gasket according to the present invention has the following features: (a) Even if the bolt tightening force is reduced, sufficient effective tightening pressure can be obtained.

(0) The amount of compression is large when subjected to compressive stress, and the ability to absorb thermal deformation and structural deformation of the flange portion of the exhaust manifold is large.

(c) It has high rebound resilience and has a high ability to absorb cyclic movements due to thermal deformation and structural deformation of the flange portion of the exhaust manifold.

(d) There is little characteristic deterioration such as sagging, and gas sealing can be maintained stably for a long period of time.

It has 1q of excellent effects such as.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of how an exhaust manifold gasket is installed, Fig. 2 is a plan view showing an example of a conventional exhaust manifold gasket, and Fig. 3 is a diagram of ■-■ in Fig. 2.
Figure 4 is a cross-sectional view showing Haku's conventional exhaust manifold gasket (the cross-sectional position is at ■ - in Figure 2).
5 is a sectional view showing another conventional exhaust manifold gasket (the cross-sectional position corresponds to line 11 in FIG. 2), and FIG. 6 is an exhaust manifold gasket according to the present invention. FIG. 7 is a cross-sectional view taken along the line Vl-Vl in FIG. 6, FIG. 8 is a compressive stress-strain diagram of the conventional gasket and the embodiment, and FIG. 9 is a plan view showing one embodiment of the present invention. is a characteristic diagram showing the relationship between the tightening time and the amount of settling in the conventional gasket and the embodiment. 27...Main body, 28-31...Aluminized copper plate,
32... Gas passage hole, 34... Ring, 35...
metal grommet. Patent applicant Neesan Gasket Co., Ltd. Agent
Patent Attorney Izumi Omori Figure 1 Figure 2 Figure 3 Figure 6 Figure 5 Figure 6 Figure 7 Figure 8 Compression ratio (chi)

Claims (1)

[Claims] A gasket for an exhaust manifold that is installed at a joint between a cylinder head and an exhaust manifold of an internal combustion engine includes a main body made of a metal plate, a hollow ring made of metal disposed in a gas passage hole, the main body and A gasket for an exhaust manifold, comprising a metal grommet attached to the ring and integrating the main body and the ring.