JPH084901A - Gasket for exhaust manifold - Google Patents

Abstract

PURPOSE:To provide a gasket for an exhaust manifold, which has high heat insulating property and at the same time completely prevents a heat insulating material from falling off. CONSTITUTION:Both main plates 9, 10 composed of thin plates of stainless steel are fastened by the first and the second flange 8c of a grommet 8 composed of the thin plates of stainless steel in the state of interposing a heat insulating material 11 composed of lightweight gas concrete between the main plates 9, 10. Accordingly, the first main plate 9 abuts on the inner surface of the first flange of the grommet 8 and the second main plate 10 is made to abut on the inner surface of the second flange 8c. The end of the first main plate 9 is bent so as to wrap the second main plate 10 and fastened, and a closed space 12 trimming the heat insulating material 11 is formed of the grommet 8 and both main plates 9, 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust manifold gasket used in automobiles and the like.

[0002]

2. Description of the Related Art In a multi-cylinder engine for an automobile, an exhaust manifold is fastened to a cylinder head in order to collect exhaust gas from each exhaust port and guide it to an exhaust pipe. As shown in FIG. 3, the exhaust manifold 1 is composed of a flange portion 2 and a collecting pipe portion 3 and is interposed between a cylinder head 5 of an engine 4 and an exhaust pipe (front pipe) 6. As a material of the exhaust manifold 1, cast iron such as FCD (spheroidal graphite cast iron) is usually used in terms of heat resistance and mass productivity. Further, in the exhaust manifold 1 of FIG. 3, the flange portion 2 is formed in a continuous plate shape, and is bolted to the cylinder head 5 via a gasket 7 made of a steel plate having substantially the same shape as the end surface thereof.

[0003]

By the way, in a water-cooled engine, a cylinder head 5 having a cooling water passage therein and an exhaust manifold 1 through which high-temperature exhaust gas passes.
And the operating temperatures are significantly different. That is, even under a high load, the cylinder head 5 is kept at a relatively low temperature of about 150 ° C., but the exhaust manifold 1 has a high temperature of about 900 ° C. near the downstream of the collecting pipe section 3. Therefore, the temperature gradient between the exhaust manifold 1 and the cylinder head 5 becomes very large, and the flange portion 2 of the exhaust manifold 1 is connected to the cylinder head 5 via the gasket 7.
The heat is conducted to the flange 2, and the temperature of the flange portion 2 drops to about 400 ° C. As a result, in the exhaust manifold 1, stress due to the difference in thermal expansion occurs between the flange portion 2 and the collecting pipe portion 3, and when operating for a long period of time, cracks due to thermal fatigue occur at the seams and the like. This could cause exhaust leakage.

In order to prevent this problem, it is effective to enhance the heat insulating property of the gasket in order to reduce the heat conduction from the exhaust manifold to the cylinder head, and various proposals have been made in the past. For example, JP-A-64-24770 discloses a gasket which is entirely formed of a heat insulating material except for a grommet made of a thin metal plate. Also,
In Japanese Utility Model Laid-Open No. 1-83152, a shim forming an exhaust passage is sandwiched between beads formed on a pair of main plates made of a thin metal plate having elasticity, and a heat insulating material is interposed between the main plates. A gasket is disclosed.

However, in the former gasket, the heat insulating material is directly pinched between the cylinder head and the flange portion. Therefore, when thermal expansion of the cylinder head and the exhaust manifold is repeated due to the operation / stop of the engine, the heat insulating material that is relatively fragile and hardly expands may gradually collapse and fall off to cause exhaust leakage. Further, also in the latter gasket, since the heat insulating material is exposed between the main plates in the outer peripheral portion, the heat insulating material may also fall off. And in order to prevent the drop-off,
Inorganic fiber woven fabric or the like has to be used as the heat insulating material, which has a problem in terms of cost and productivity.

The present invention has been made in view of the above circumstances,
An object of the present invention is to provide an exhaust manifold gasket that has high heat insulation properties and completely prevents the heat insulation material from falling off.

[0007]

Therefore, in the exhaust manifold gasket according to claim 1 of the present invention, a gasket interposed between the exhaust port side end surface of the cylinder head of the internal combustion engine and the flange end surface of the exhaust manifold. ,
Grommet made of a thin metal plate, which comprises a tubular pipe portion forming an exhaust passage, and annular first flanges and second flanges that are in contact with the exhaust port side end face and the flange end face, respectively, that are continuous with the pipe portion. And the first of this grommet
A main plate made of a thin metal plate, which is joined to the flange and the second flange and cooperates with the grommet to form a closed space, and a low heat conductive member installed in the closed space.

Further, in the exhaust manifold gasket according to claim 2, in the gasket according to claim 1, the low thermal conductive member is made of ceramics. Further, in the exhaust manifold gasket according to claim 3, in the gasket according to claim 1, the main plate is joined to a first main plate joined to the first flange side of the grommet and a second flange side of the grommet. It is composed of a second main plate.

Further, in the exhaust manifold gasket according to claim 4, in the gasket according to claim 2, the ceramic is glass wool or lightweight cellular concrete.

[0010]

In the exhaust manifold gasket according to claim 1 of the present invention, the heat from the flange portion is conducted to the cylinder head mainly through the grommet and the main plate made of a thin metal plate, but the heat transfer area of both is small. Therefore, the temperature drop of the flange is small. Further, since the low heat conductive member is held in the closed space formed by the grommet and the main plate, it does not fall off even after long-term operation.

Further, in the exhaust manifold gasket according to claim 2, since the low heat conductive member is ceramics,
The heat insulation of the entire gasket is very high. Further, the exhaust manifold gasket according to claim 3 is manufactured by forming the first main plate and the second main plate by punching or the like, and integrating them by caulking with a heat insulating material interposed between the two main plates. To be done.

In the exhaust manifold gasket of the fourth aspect, a heat insulating material made of glass wool or lightweight cellular concrete having a predetermined thickness is formed by punching or the like, and is interposed between the first main plate and the second main plate.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In the description of the embodiments, the same members as those of the conventional device described above are designated by the same reference numerals, and duplicated description will be omitted. FIG. 1 is a plan view showing an embodiment of the exhaust manifold gasket according to the present invention, and FIG. 2 is a sectional view taken along line II--II in FIG. As shown in these drawings, the gasket 7 of the present embodiment includes a grommet 8, first and second main plates 9 and 10, and a low heat conductive member (hereinafter, heat insulating material) 11. In the case of this embodiment, the materials of the grommet 8 and both main plates 9 and 10 are both thin stainless steel plates, and the thickness of the grommet 8 is slightly larger than that of both main plates 9 and 10. The material of the heat insulating material 11 is lightweight foam concrete.

The grommet 8 has a long cylindrical pipe portion 8a which constitutes an exhaust passage, and an elliptic first portion which is continuous with the pipe portion 8a and whose outer surface is in contact with the exhaust side end surface 5a of the cylinder head 5. The flange 8b and an outer surface of the flange 8b are formed of an oval second flange 8c that abuts the flange portion 2 of the exhaust manifold 1. On the other hand, both of the main plates 9 and 10 and the heat insulating material 11 are formed by punching or the like so that their outer shapes are substantially equal to the contour of the gasket 7.

The two main plates 9 and 10 are caulked by the first and second flanges 8b and 8c of the grommet 8 with the heat insulating material 11 interposed therebetween. Therefore, the first main plate 9 contacts the inner surface of the first flange 8b of the grommet 8, and the second main plate 10 contacts the inner surface of the second flange 8c. The end portion 9a of the first main plate 9 is bent and crimped so as to wrap the second main plate 10, and the heat insulating material 11 is formed by the grommet 8 and both main plates 9 and 10.
There is formed a closed space 12 for interior.

The operation of this embodiment will be described below. When the engine 4 is operated, the temperature of the exhaust manifold 1 through which the high-temperature exhaust gas flows becomes high, while the cylinder head 5 is kept at a relatively low temperature. As a result, as described above, the temperature gradient between the exhaust manifold 1 and the cylinder head 5 becomes extremely large, and the flange portion 2 is inserted via the gasket 7.
Heat is conducted to the cylinder head 5. Further, in this embodiment, since the heat insulating material 11 is internally provided in the gasket 7, heat conduction is mainly performed through the grommet 8 and the first and second main plates 9 and 10.

However, since these members are both formed of a thin plate of stainless steel, the heat transfer area is very small and the amount of heat transfer to the cylinder head 5 is extremely small. As a result, the temperature drop of the flange portion 2 was suppressed, and the exhaust manifold 1 was not cracked due to thermal fatigue even after long-term operation. Further, since the heat insulating material 11 is installed in the closed space 12 formed by the grommet 8 and the two main plates 9 and 10, it does not drop off, and the initial performance can be maintained for a long period of time.

Although the description of the specific embodiment has been completed, the embodiment of the present invention is not limited to this embodiment. For example, although stainless steel was used as the material of the main plate and lightweight foamed concrete was used as the material of the low thermal conductive member in the above-mentioned embodiments, other types of heat-resistant alloys or ceramics such as glass wool may be used. Further, the joining of the first main plate and the second main plate may be performed by spot welding or the like instead of caulking.

[0019]

In the exhaust manifold gasket according to claim 1 of the present invention, since the heat transfer area between the grommet and the main plate is small, heat transfer from the flange portion of the exhaust manifold to the cylinder head is reduced, and the temperature of the flange portion is reduced. The exhaust manifold will not crack due to the deterioration. Further, since the low heat conductive member is held in the closed space formed by the grommet and the main plate, it does not drop out even after long-term operation, and the initial performance is maintained for a long period of time. .

Further, in the exhaust manifold gasket according to claim 2, since the low heat conductive member is ceramics,
The heat insulating property of the entire gasket becomes extremely high, and the temperature decrease of the flange portion is further prevented. Further, in the exhaust manifold gasket according to claim 3, since the main plate is composed of the first main plate and the second main plate, a complicated shape can be easily manufactured, and the gasket can be integrated by caulking or the like. Manufacturing cost can be reduced.

Further, in the exhaust manifold gasket according to claim 4, since glass wool or lightweight cellular concrete is used as the ceramics for the heat insulating material, the gasket can be manufactured lightweight and at low cost.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is an exploded perspective view showing an exhaust system of the engine.

[Explanation of Codes] 1 Exhaust manifold 2 Flange part 3 Collecting part 4 Engine 5 Cylinder head 5a Exhaust port side end face 7 Gasket 8 Grommet 9 First main plate 10 Second main plate 11 Low heat conductive member 12 Closed space

Claims (4)

[Claims] 1. A gasket interposed between an end surface of an exhaust port side of a cylinder head of an internal combustion engine and an end surface of a flange of an exhaust manifold, wherein a pipe portion forming an exhaust passage and the exhaust gas continuously connected to the pipe portion. A grommet made of a thin metal plate, which is composed of an annular first flange and an annular second flange that come into contact with the port-side end face and the flange end face, respectively, and is joined to the first and second flanges of the grommet and cooperates with the grommet. An exhaust manifold gasket, comprising: a main plate made of a thin metal plate that constitutes a closed space, and a low heat conductive member installed in the closed space. 2. The exhaust manifold gasket according to claim 1, wherein the low thermal conductive member is made of ceramics. 3. The first main plate joined to the first flange side of the grommet, and the second main plate of the grommet.
The exhaust manifold gasket according to claim 1, comprising a second main plate joined to the flange side. 4. The ceramic is glass wool or lightweight cellular concrete.
Exhaust manifold gasket described.