JPH0245464Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement in the structure of a gasket used in an engine exhaust system, particularly a gasket having an exhaust flow hole and a bolt insertion hole.

(Prior Art) For example, as disclosed in Japanese Utility Model Application Publication No. 50-83415 (see FIG. 7), the exhaust system 2 of the automobile 1 is
The exhaust manifold 4 has one end branched into a plurality of parts and is connected to the engine 3, a catalytic converter 5 that removes harmful components from exhaust gas, and a muffler 6 that reduces exhaust noise. 5 and 6 are connected in a line via exhaust pipes 7...7. In this case, each of the above-mentioned members 4, 5, 6 and the exhaust pipe 7 are connected by flanges formed at their corresponding ends. Usually, they are connected by bonding them together.

Incidentally, in each connection part A...A between the flanges of each of the members 4, 5, and 6 and the flange of the exhaust pipe 7, a gasket is usually interposed between the pair of flanges. 4, 5, 6 and the exhaust pipe 7 are exposed to high temperatures due to exhaust gas from the engine 3, the flange is thermally deformed and the surface pressure between the flange and the gasket is reduced, or the flange and gasket are There is a gap between
There was a problem in that the sealing performance at each connection part A...A deteriorated.

Therefore, according to the above publication, as shown in FIG. 8, a gap B is provided in the center of a pair of flange members 9 and 10 fastened by bolts 8...8, and
A joint C between a pair of exhaust pipes 11 and 12 is placed in this gap B.
A configuration is shown in which a sealing member 13 for sealing is attached, and the sealing member 13 is pressed against the joint C by the curved portions of the pair of flange members 9 and 10. However, even with such a configuration, if both flange members 9 and 10 become hot and are thermally deformed in the direction a, the pressing force acting on the seal member 13 from the curved portions of both flange members 9 and 10 will decrease. However, as a result, the surface pressure of the sealing member 13 on the joint portion C may become insufficient, and the sealing performance of the joint portion C may deteriorate.

(Purpose of the invention) The present invention deals with the above-mentioned problems in the exhaust system of automobiles. By improving the structure of the gasket installed, even if the flanges are heated to a high temperature by exhaust gas passing through the exhaust manifold or exhaust pipe and are thermally deformed, the connecting part between the pair of flanges can be The purpose is to ensure sealing performance.

(Structure of the invention) In order to achieve the above object, the present invention is characterized by the following structure.

That is, it is installed at the connection part of the exhaust manifold, muffler, exhaust pipe, etc. in the exhaust system of the engine,
A gasket for an engine exhaust system having an exhaust flow hole and a bolt insertion hole is made of a pair of metal plates forming both end surfaces of the gasket, a heating expansion agent such as vermiculite, vermiculite, or mica, and ceramic fiber. a thermally expandable material filled between the pair of metal plates, and a metal member interposed around the bolt insertion hole between both metal plates, and the thermally expandable material is filled between the pair of metal plates. It is characterized by being wrapped in a metal plate and a metal member. According to such a configuration, due to the properties of the thermal expansion agent constituting the thermal expansion material, the volume of the thermal expansion material increases as the temperature rises. Even if the flanges of the pair of flanges are thermally deformed so as to separate from each other, a gap is prevented from being created between the pair of flanges due to expansion of the thermally expandable material. In this case, since the thermally expandable material is surrounded by a pair of metal plates and a metal member, the entire body is kept at a uniform temperature, and the amount of thermal expansion or the surface pressure against the flange is stable and good. In addition to providing excellent sealing performance, it also makes it difficult to absorb water from the outside, resulting in high reliability.

By the way, since this thermal expansion material has plasticity, for example, a gasket made of only thermal expansion material is interposed between a pair of metal plates and is interposed between a pair of flanges, and both flanges are tightened with bolts. In this case, the tightening torque of the bolt will not be stable, and after tightening, the tightening force will gradually decrease, resulting in problems. However, in the gasket according to the present invention, since the periphery of the bolt insertion hole is made of a metal member,
The amount of compression of the gasket due to the bolt tightening force is suppressed, and the tightening torque during tightening is stabilized, and problems such as a decrease in the tightening force do not occur even after tightening.

(Effect of the invention) According to the above configuration, since thermal expansion material is used as a component of the gasket for the engine exhaust system, the exhaust manifold, exhaust pipe, etc. are exposed to high temperature exhaust gas and the pair of Even if the flanges are thermally deformed so as to separate from each other, the thermal expansion material in the gasket interposed between the pair of flanges expands, and the thermal expansion material is wrapped by the pair of metal plates and metal members. Because of this, the whole part expands evenly and a stable surface pressure is obtained against the gasket, and it also becomes difficult to absorb water, so that good sealing performance between the two flanges is maintained over a long period of time. It turns out.

In addition, since the periphery of the bolt insertion hole in the gasket is made of a metal member, the tightening force when fastening a pair of flanges with bolts with the gasket interposed acts on the metal member, which makes it stable. Both flanges can be reliably fastened with the same fastening force, and the tightening force of the bolt can be prevented from decreasing after both flanges are fastened.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

As shown in FIG. 1, the gasket 20 has an exhaust gas flow hole 21 provided at the center and two bolt insertion holes 22, 22 provided at both ends.
As shown in FIG. 2, when this gasket 20 is interposed between flanges 23a and 24a formed at the ends of two exhaust pipes 23 and 24, exhaust passage 23
b, 24b, and the bolt insertion holes 22, 22 communicate with both flanges 23, 24b.
This is for inserting a bolt 25 for fastening the bolts 24a and 24a.

Both end surfaces of this gasket 20 are composed of a first metal plate 26 and a second metal plate 27, and as shown in FIG. Edge 27 of the bent part of
a, 27a are superimposed on the inner peripheral edge and outer peripheral edge of the first metal plate 26, respectively.

Then, the first metal plate 26 and the second metal plate 27
A thermal expansion material 28 is filled between the first metal plate 26 and the second metal plate 27, and the bolt insertion holes 22, 22 are formed between the first metal plate 26 and the second metal plate 27.
Washer-like metal members 29, 29 are interposed, and the holes 29a, 29a of the members 29, 29 constitute the bolt insertion holes 22, 22, and the metal members 29, 29 and the 1. The thermal expansion material 28 is formed by the second metal plates 26 and 27.
is said to be in a state of envelopment. The thermal expansion material 28 is a mixture of a thermal expansion agent with a high coefficient of thermal expansion, such as vermiculite, vermiculite, or mica, and ceramic short fibers, and has the property of significantly increasing its volume as the temperature rises. It is something that you have.

According to the above structure, the two exhaust pipes 23 and 24 shown in FIG.
When connecting with the bolt 25 and nut 30, the tightening force of the bolt 25 and nut 30 is equal to the gasket 2.
Metal member 2 around bolt insertion hole 22 at 0
Therefore, the amount of compression of the gasket 20 due to the tightening force is suppressed, and both flanges 23a and 24a are fastened with a stable tightening force. In other words, if the periphery of the bolt insertion hole 22 in the gasket 20 is made of a thermally expandable material like the other parts, the bolt 25 and the nut 3 can be inserted with this gasket interposed.
When both flanges 23a and 24a are fastened together by the 0, the thermal expansion material has plasticity, so the tightening torque of the bolts 25 and nuts 30 is not stable, making it difficult to securely fasten the bolts 25 and nuts 30. If the flanges 23a, 24a become loosely tightened, this will lead to other problems. However, if the periphery of the bolt insertion hole 22 in the gasket 20 is formed of the metal member 29 as described above, such a problem will not occur, and therefore the fastened state of both flanges 23a and 24a will be maintained. .

On the other hand, the exhaust pipes 2 connected as described above
When high-temperature exhaust gas discharged from the combustion chamber of an engine (not shown) passes through the insides of the exhaust gases 3 and 24, both exhaust pipes 23 and 24 become hot due to the heat of this exhaust gas. flange 2
The vicinity of exhaust passages 23b, 24b in 3a, 24a is thermally deformed in the direction shown by arrow X in FIG. 2, and both flanges 23a, 24a are separated from each other. At this time, in the gasket 20 interposed between both flanges 23a and 24a, the thermal expansion material 2
8, due to the properties of the heating expansion agent that constitutes it,
The first gasket 20, whose volume increases when the gasket 20 reaches a high temperature state, forms both end surfaces of the gasket 20.
The second metal plates 26 and 27 are connected to both flanges 23a,
It is pressed against the end face of 24a with great force.
In this case, since the thermal expansion material 28 is surrounded by the first and second metal plates 26 and 27 and the metal members 29 and 29, the entire thermal expansion material 28 is kept at a uniform temperature and expands evenly. , stable surface pressure can be obtained over a wide area against the gasket. Therefore, even though the flanges 23a and 24a are separated from each other, they are reliably sealed by the gasket 20, and therefore, even if the exhaust pipes 23 and 24 become hot due to exhaust gas, Even in this case, leakage of exhaust gas from between the flanges 23a and 24a is reliably prevented. Moreover, since the thermal expansion material 28 is wrapped as described above, it becomes difficult to absorb water from the outside, and good sealing performance is maintained over a long period of time.

Note that the first metal plate 26 of this gasket 20 is
As shown in FIG. 2, there is a protrusion 26 that is folded into the bolt insertion hole 22 (hole 29a of the metal member 29) and that protrudes inward from the hole 22.
a is formed, which is connected to both exhaust pipes 23, 2.
4, when the gasket 20 is applied to the lower surface of the flange 23a of one exhaust pipe 23 and the bolt 25 is inserted from above into the through hole 23' of the flange 23a and the bolt insertion hole 22 of the gasket 20, This is to temporarily fix the gasket 20 to one of the exhaust pipes 23 by engaging the thread groove of the bolt 25 with the protrusion 26a.

In addition, in this embodiment, the gasket according to the present invention is interposed at the joint between two exhaust pipes, but it is also used at the joint between a muffler and an exhaust pipe in an automobile exhaust system, or between a catalytic converter and an exhaust pipe. This gasket may be interposed at each connection portion such as the connection portion with the

Next, a second embodiment of the present invention shown in FIGS. 4 to 6 will be described.

In this second embodiment, as shown in FIG. 4, the gasket 40 has a rectangular shape, and has an exhaust flow hole 41 in the center thereof, and bolt insertion holes 42 in the four corners. ing.
As shown in FIGS. 5 and 6, a thermal expansion material 45 and a metal member 46 similar to those in the first embodiment are placed between the two metal plates 43 and 44 constituting both end surfaces of the gasket 40. Although interposed, the metal member 46 has a corner portion 46 in which holes 46a...46a forming the four bolt insertion holes 42...42 are formed.
b...46b and these corner parts 46b...46
The gasket 40 is composed of side portions 46c, .
Also in this embodiment, the thermal expansion material 45 is surrounded by the metal plates 43 and 44 and the metal member 46.

Therefore, the gasket 4 in this second embodiment
0 is interposed between two flanges of exhaust pipes, etc., even when both flanges are fastened, the tightening force is equal to the corner portions 46b...46 of the metal member 46.
b, the amount of compression of the gasket 40 is suppressed, making it possible to reliably fasten with a stable tightening force. Even if they are thermally deformed so as to separate from each other, the thermally expandable material 45 in the gasket 40 is kept at a uniform temperature and expands evenly, so that the space between both flanges is reliably sealed with stable surface pressure. Become.
Furthermore, the thermal expansion material 45 is less likely to absorb water from the outside, and good sealing performance is maintained for a long period of time.

[Brief explanation of the drawing]

Figures 1 to 3 show the first embodiment of the present invention, where Figure 1 is a plan view of the gasket alone, Figure 2 is an enlarged vertical sectional view of the main part taken along the line of Figure 1, and Figure 3 1 is an enlarged vertical cross-sectional view of the main part taken along the line in FIG. 1. 4 to 6 show a second embodiment of the present invention, in which FIG. 4 is a plan view of the gasket alone, FIG. 5 is an enlarged longitudinal sectional view of the main part taken along the line of FIG. FIG. 4 is an enlarged vertical cross-sectional view of the main part taken along the line in FIG. Further, FIGS. 7 and 8 show conventional examples, with FIG. 7 being a schematic diagram of the exhaust system of an automobile, and FIG. 8 being a fragmentary enlarged view of the main parts. 20, 40... Gasket, 21, 41... Exhaust flow hole, 22, 42... Bolt insertion hole, 26,
27, 43, 44...Pair of metal plates, 28, 45
...Thermal expansion material, 29,46...Metal member.

Claims (1)

[Scope of utility model registration request] A gasket for an engine exhaust system having an exhaust flow hole and a bolt insertion hole, the gasket having a thermal expansion agent such as vermiculite, vermiculite, or mica and ceramic fiber between a pair of metal plates constituting both end surfaces of the gasket. A metal member is interposed around the bolt insertion hole between the pair of metal plates to regulate the amount of compression of the gasket due to the tightening force of the bolt, and A gasket structure for an engine exhaust system, characterized in that the thermal expansion material is covered with a plate and a metal member.