JPH08260951A - Connection structure of exhaust pipe - Google Patents

Abstract

PURPOSE: To provide a connection structure which is excellent in sealability and whose accuracy of a sealed surface is not required to be excellent in the connection of exhaust pipes. CONSTITUTION: The diameter of an end part 2a of a second exhaust pipe 2 is set larger than the diameter of an end part 1a of a first exhaust pipe 1, forward edges 11b, 2b of the first and second exhaust pipes 1, 2 are exposed from end faces 3a, 4a of first and second flanges 3, 4, and a gasket 5 forms the wire of approximately S-shape in vertical section to be ring-shaped. The forward edge 1b of the first exhaust pipe 1 is inserted in a lower opening 5a of the S-shaped section, the forward edge 2b of the second exhaust pipe 2 is inserted in an upper opening 5b of S-shaped section, the first flange 3 and the second flange 4 are bolt-tightened to each other, and the gasket 5 is closely attached to the flanges 3, 4 and the forward edges 1b, 2b of the exhaust pipes 1, 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for connecting exhaust pipes of an automobile.

[0002]

2. Description of the Related Art When connecting exhaust pipes of an automobile, a gasket (also referred to as a seal used for sealing a stationary portion or a fixing seal) is used to prevent exhaust gas from leaking from a connecting portion.

As an exhaust pipe connecting structure using this gasket, for example, one shown in FIG. 4 is known.

In the figure, reference numerals 31 and 32 are a first exhaust pipe and a second exhaust pipe, respectively. At the ends of the first and second exhaust pipes 31, 32, there are annular first and second exhaust pipes, respectively. The second flanges 33 and 34 are welded. Further, reference numeral 35 in the drawing denotes an annular flat gasket (a flat gasket used in a state of being cut out from the sheet).

Then, the first exhaust pipe 31 and the second exhaust pipe 32
To connect with, the first and second flanges 33 and 34 are fastened with bolts 36 and nuts 37 with the flat gasket 35 sandwiched between the first and second flanges 33 and 34.

Due to this fastening force, the flat gasket 35
Is tightened to prevent exhaust gas from leaking from between the first flange 33 and the second flange 34 (connection portion).

[0007] Incidentally, this type is, for example, the actual exploitation 6
1-58793.

[0008]

By the way, in such a conventional exhaust pipe connecting structure, the flat gasket 35 is compressed in the plate thickness direction so that the sealability (fluid or the like leaks through the seal portion). However, since the flat gasket 35 is flat and the tightening force of the bolt 36 is limited, the gasket tightening force (gasket tightening force (gasket tightening force) is obtained). It is difficult to increase the pressure exerted per unit area of the gasket when tightened. Also, the bolt 36
Since the fastening force of No. 1 directly becomes the compression force to the flat gasket 35, even if a high gasket fastening force is obtained at the time of fastening, the bolt 36 is fastened due to stress relaxation (a phenomenon in which the stress decreases with time). When the force is loosened, the sealing property of the flat gasket 35 is also deteriorated.

For this reason, the conventional exhaust pipe connecting structure has a problem that the sealing performance is insufficient or unstable.

Further, in order to prevent exhaust gas from leaking through a slight gap between the first and second flanges 33 and 34 and the flat gasket 35, the sealing surfaces of the first and second flanges 33 and 34 and the flat gasket 35 ( It is the surface where the gasket and the material to be sealed come into contact with each other for sealing, and both the surface of the gasket itself and the surface of the material to be sealed) must be finished with high accuracy in terms of dimensional accuracy, surface roughness, and geometric accuracy. there were.

The present invention has been made under the above circumstances, and an object thereof is to provide a connecting structure which has a high sealing property in connecting exhaust pipes to each other and does not require a highly accurate sealing surface. There is.

[0012]

The present invention has been made in view of such a problem, and the invention described in claim 1 is the first flange provided at the end of the first exhaust pipe. And a second flange provided at an end of the second exhaust pipe, a gasket is arranged between the first flange and the second flange.
An exhaust pipe connecting structure in which the first exhaust pipe and the second exhaust pipe are connected to each other by bolting a flange,
The end diameter of the second exhaust pipe is set to be larger than the end diameter of the first exhaust pipe, and the tip edges of the first and second exhaust pipes are exposed from the end surfaces of the first and second flanges, respectively. Then, the gasket is formed by forming a wire rod having a substantially S-shaped vertical cross section into a ring shape, and inserting the tip edge of the first exhaust pipe into the lower opening of the S-shaped cross section. The leading edge of the second exhaust pipe is inserted into the upper opening of the circular cross section, the first flange and the second flange are bolted together, and the gasket is attached to the leading edges of the flanges and the exhaust pipes. Characterized by close contact.

The invention described in claim 2 is characterized in that the wire of the gasket is formed of a core material having a spring property and a sealing material covering the core material.

[0014]

According to the invention described in claim 1, since the gasket is brought into close contact with the first and second flanges and the tip edges of the first and second exhaust pipes to form a plurality of sealing surfaces, the conventional structure As described above, the sealing performance is improved as compared with the case where the sealing surface is only the flange end surface.

In addition, since the gasket is deformed three-dimensionally and brought into close contact with the flange or the like, compared with the conventional case where the flat gasket is compressed only in the plate thickness direction and brought into close contact, the gasket tightening force by bolt fastening is used. And the sealing performance is improved.

Further, since the flat gasket is not compressed by compressing it in the plate thickness direction as in the conventional case, it is not necessary to finish the sealing surfaces of the flange and the gasket with high accuracy.

According to the second aspect of the present invention, the deformability of the gasket is enhanced by the core material having a spring property, and the sealing material is easily attached to the flange and the tip edge of the exhaust pipe.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

Reference numerals 1 and 2 in FIG. 1 denote a first exhaust pipe and a second exhaust pipe, respectively, and end portions 1a, 2a of these exhaust pipes 1, 2 have a first flange 3 and a second flange 2, respectively. The flange 4 is welded. Reference numeral 5 in the drawing is a gasket.

The second exhaust pipe 2 has a diameter larger than that of the first exhaust pipe 1. However, the diameter of only the end 2a may be wide and wide.

The first flange 3 has an annular shape, and a counterbore portion 3b is formed on the end surface 3a thereof.
The leading edge 1b of the first exhaust pipe 1 (hereinafter referred to as "first leading edge 1"
b)) is exposed from the end face 3a.

Similarly, the second flange 4 also has an annular shape, and the tip edge 2b of the second exhaust pipe 2 (hereinafter, referred to as "second tip edge 2b") is exposed from its end surface 4a. The welding position of the second flange 4 is set.

The exposure amount L2 of the second tip edge 2b is the first
The exposure amount L1 of the leading edge 1b is set to be smaller, and the difference (L1-L2) is set to be slightly smaller than the wall thickness t (see FIG. 2) of the gasket 5 described later.

As shown in FIG. 2, the gasket 5 is a ring-shaped wire having a substantially S-shaped vertical cross section.

This wire is composed of a core material 6 (for example, spring steel) having a substantially S-shaped vertical section and having a spring property, and a seal material 7 (for example, mild steel, carbon fiber-containing phenol resin) covering the core material 6. Has been formed.

As will be described later, the first leading edge 1b is inserted into the lower opening 5a of the S-shaped cross section, and the upper opening 5 is formed.
When the second tip edge 2b is inserted into b and the flanges 3 and 4 are fastened, the sealing material 7 of the gasket 5 is in close contact with both flanges 3 and 4 and both tip edges 1b and 2b.
The cross-sectional shape and size of the gasket 5 are set.

Further, the width H of the gasket 5 is set to be smaller than the exposed amount L1 of the first tip edge 1b, whereby the lower opening 5a side is pulled when the flanges 3 and 4 are fastened, as will be described later. It is designed to improve the hermeticity.

In order to connect the first exhaust pipe 1 and the second exhaust pipe 2, as shown in FIG. 1, the first tip edge 1b is inserted into the lower opening 5a of the gasket 5 and the upper opening is opened. The second tip edge 2b is inserted into the portion 5b, and the end surface 3a of the first flange 3 and the end surface 4a of the second flange 4 are butted against each other.
In this state, as shown in FIG. 3, the flanges 3 and 4 are fastened with bolts 8 and nuts 9.

Then, due to this fastening force, the gasket 5 is three-dimensionally deformed while receiving the tension and compression force by the first tip edge 1b and the second tip edge 2b as shown in FIG. As a result, the sealing material 7 of the gasket 5 is brought into close contact with both the leading edges 1b, 2b and the first flange 3
It also comes into close contact with the spot facing portion 3b and the end surface 4a of the second flange 4.

At this time, since the gasket 5 has the deformability enhanced by the core material 6 and has a certain shape-retaining property, the seal material 7 is deformed into an S-shape having a rectangular section. The exhaust pipes 1 and 2 come into close contact with the leading edges 1b and 2b.

As a result, the gasket 5 and the exhaust pipes 1, 2 are
And a plurality of sealing surfaces are formed between the flanges 3 and 4, and the sealing performance is improved as compared with the conventional case where the sealing surface is only the flange end surface.

Moreover, since the gasket 5 is three-dimensionally deformed and brought into close contact with the flanges 3, 4, etc., compared with the conventional case where the flat gasket 35 is compressed only in the plate thickness direction and brought into close contact with the flanges 3, 4, etc. The gasket tightening force due to the bolt tightening is improved, and the sealing performance is further improved.

Furthermore, as shown in FIG. 3, since the cross section of the gasket 5 extends in a zigzag shape perpendicular to the direction Y of the exhaust flow, the exhaust is unlikely to leak from the joint.

On the other hand, as shown in FIG. 3, the first tip edge 1b
Since the second tip edge 2b and the second tip edge 2b are joined in different steps, even if the exhaust pipes 1 and 2 thermally expand due to exhaust heat, the gasket 5 follows this expansion and the hermeticity is maintained.

Further, since the flat gasket 35 is not compressed in the plate thickness direction to obtain the sealing property as in the conventional case, it is not necessary to finish the sealing surfaces of the flanges 3 and 4 and the gasket 5 with high accuracy. As a result, the manufacturing cost can be reduced.

[0036]

As described above, according to the invention described in claim 1, the gasket is in close contact with the first and second flanges and the tip edges of the first and second exhaust pipes to form a plurality of seals. Since the surface is formed, the sealing performance is improved as compared with the conventional case where the sealing surface is only the flange end surface.

Moreover, since the gasket is deformed three-dimensionally and brought into close contact with the flange or the like, compared with the conventional case where the flat gasket is compressed only in the plate thickness direction and brought into close contact, the gasket tightening force by bolt fastening is increased. And the sealing performance is improved.

Further, since the flat gasket is not compressed in the plate thickness direction to obtain the sealing property as in the conventional case, it is not necessary to finish the sealing surfaces of the flange and the gasket with high accuracy.

According to the second aspect of the present invention, the deformability of the gasket is enhanced by the core material having a spring property, and the sealing material is easily attached to the flange and the tip edge of the exhaust pipe.

[Brief description of drawings]

FIG. 1 is an exploded cross-sectional view showing an exhaust pipe connection structure according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a gasket in the same embodiment.

FIG. 3 is a cross-sectional view showing a connection state of exhaust pipes in the same embodiment.

FIG. 4 is a cross-sectional view showing an exhaust pipe connection structure in a conventional example.

[Explanation of symbols]

 1 First Exhaust Pipe 1a End of First Exhaust Pipe 1b Tip Edge of First Exhaust Pipe 2 Second Exhaust Pipe 2a End of Second Exhaust Pipe 2b Tip Edge of Second Exhaust Pipe 3 First Flange 3a First Flange End face 3b Counterbore 4 Second flange 4a End face of second flange 5 Gasket 5a Lower opening 5b Upper opening 6 Core material 7 Sealing material

Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F16L 23/028 23/16

Claims (2)

[Claims] 1. A gasket is arranged between a first flange provided at the end of the first exhaust pipe and a second flange provided at the end of the second exhaust pipe, and the gasket is arranged between the first flange and the second flange. An exhaust pipe connecting structure in which a second flange is bolted to connect the first exhaust pipe and the second exhaust pipe, wherein an end diameter of the second exhaust pipe is equal to an end of the first exhaust pipe. The diameter is set larger than the part diameter, and the tip edges of the first and second exhaust pipes are respectively set to the first and second exhaust pipes.
The gasket is exposed from the end surface of the second flange, and the gasket is formed by forming a wire rod having a substantially S-shaped vertical cross section into a ring shape, and a tip edge of the first exhaust pipe is formed in a lower opening of the S-shaped cross section. While inserting, the tip edge of the second exhaust pipe is inserted into the upper opening of the S-shaped cross section, the first flange and the second flange are bolted, and the gasket is attached to the flanges and the flange. Exhaust pipe connection structure characterized by being closely attached to the tip edges of both exhaust pipes. 2. The exhaust pipe connecting structure according to claim 1, wherein the wire material of the gasket is formed of a core material having a spring property and a sealing material covering the core material.