JPH07111131B2 - Flange joint structure of automobile exhaust pipe system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flange joint structure for an automobile exhaust pipe system in which a spiral gasket is sandwiched between opposed pipe end flanges.

[0002]

2. Description of the Related Art Generally, in this type of flange joint structure, as shown in FIG. 3, generally, the flat surface shape in which the flange sealing surfaces 26a, 27a which are the gasket clamping surfaces of the opposed pipe end flanges 26, 27 are parallel to each other. Is doing. Also,
As the spiral gasket 21 loaded between the flange sealing surfaces 26a and 27a, a metal hoop 22 that bends in a V shape or a W shape in cross section and an inorganic filler 2 such as an expanded graphite tape are used.
What is formed by superimposing and integrating 3 and 3 in a spiral shape is used. Thus, according to such a flange joint structure (hereinafter referred to as "conventional structure"), the flange sealing surfaces 26a, 27
The spiral gasket 21 is loaded between a and (see FIG. 3).
(See (A)), tighten the flanges 26 and 27, and secure the spiral gasket 21 with the flange sealing surfaces 26a and 27a.
It is possible to connect the flanges 26 and 27 in a sealed state by pressing.

[0003]

However, in the conventional structure, it is extremely difficult to secure the sealing property at a low tightening surface pressure. That is, the spiral gasket 21 used in the conventional structure (hereinafter referred to as “conventional gasket”) is
Since the overlapped annular layers of the hoop 22 and the filler 23 are engaged with each other in a corrugated form, when the flanges 26 and 27 are tightened, the filler 23 is compressed and deformed in the axial direction even though the hoop 22 is compressed and deformed. Since the flow to the bent portion of the hoop is not smooth, as shown in FIG.
A gap 24 is generated between the filler 2 and the filler 23, so that a so-called leak path is likely to occur.

In addition, FF (Front engine Front drive)
Compared to FR (Front engine Reardrive) cars, exhaust pipes generally have larger vibrations in vehicles, so recent FF
Due to the tendency of increasing tendency, it is necessary to take sufficient vibration countermeasures for the flange joint structure in the exhaust pipe, but it is difficult for the conventional structure to satisfy such demand.

That is, in the conventional structure, since the flange sealing surfaces 26a and 27a have a parallel plane shape, when the flanges 26 and 27 are vibrated, the conventional gasket 21 and the sealing surfaces 26a and 27a are separated from each other. Relative motion is likely to occur between the two. As a result, the filler 23 is worn out,
The sealing performance will be reduced, and there will be a problem with durability. Further, when the parallelism between the sealing surfaces 26a and 27a is impaired by the vibration, the conventional gasket 21 is difficult to deform in the axial direction, and thus the change in the parallelism cannot be followed.
The contact between the sealing surfaces 26a and 27a and the gasket 1 becomes insufficient, and the sealing performance deteriorates. Furthermore, since the flanges 26 and 27 are fastened by the fastening bolts so that they cannot move relative to each other, vibration may cause an excessive load to act on the flange fastening portion and damage them.

An object of the present invention is to solve the above problems and to provide a flange joint structure for an automobile exhaust pipe which can exhibit a good sealing function at a low tightening surface pressure without being adversely affected by vibration. It is what

[0007]

In order to achieve the above object, in the flange joint structure for an automobile exhaust pipe system according to the present invention, in particular, a hemispherical surface in which flange sealing surfaces, which are gasket clamping surfaces of both flanges, are parallel to each other. The spiral gasket has a shape such that the flat hoop-shaped metal hoop and the tape-shaped filler can be deformed in the axial direction so that the gasket end surface has a hemispherical shape corresponding to the flange sealing surface. It is proposed that the two flanges are superposed and integrated in a spiral shape, and that both flanges are fastened via a spring.

[0008]

[Function] Since both the hoop and the filler are flat plate shapes which are straight in the axial direction, when an external force in the axial direction is applied,
By causing a slip between the two and deforming in the axial direction, the seal surface contact surface, which is the gasket end surface, can have an arbitrary hemispherical shape.
Therefore, when the gasket is loaded and clamped between the flange seals, the contact surface of the seal surface conforms to the flange seal surface having a hemispherical shape and is deformed, and the flange seal surface can be properly contacted. At this time, since the hoop and the filler do not have a bent portion unlike the conventional gasket, the filler flows smoothly when deformed in the axial direction,
There is no gap between the hoop and the filler. Moreover, the hoop is radially deformed along with the axial deformation, that is, the hoop is radially deformed so as to compress the filler, and thus the degree of adhesion between the hoop and the filler,
As a result, the gasket density increases. In addition, since the flange sealing surface has a hemispherical shape that inclines toward the center, when the gasket is tightened, a component force that compresses the gasket toward the center acts, and the hoop collapses toward the center. It will be. As a result, the filler is further compressed, and the adhesion between the hoop and the filler or the gasket density is significantly increased.

Therefore, the sealing between the flange sealing surfaces can be satisfactorily performed with a low tightening surface pressure.

Further, since both flanges are fastened via a spring, even if vibration is applied, it is absorbed and relaxed by the action of the spring, and an excessive load acts on the flange fastening portion. There is no. Moreover, even if the parallelism between both flange seal faces changes due to such vibration absorbing action, the gasket is easily deformed in the axial direction as described above. Changes easily and keeps proper contact with the sealing surface, and there is no fear that the sealing performance will deteriorate. Further, even if the filler material wears due to the vibration of the flange, the metal hoop serves as a barrier and prevents the wear, so that the durability of the gasket is improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be specifically described below with reference to the embodiments shown in FIGS.

As shown in FIG. 1, the flange joint structure of the automobile exhaust pipe system of this embodiment has sheet metal annular flanges 6 and 7 welded to the ends of the automobile exhaust pipes 4 and 5 between them. With the spiral gasket 1 interposed, the coil spring 10 is fastened with fastening bolts 11 ...

The upstream flange 6 is a press-molded annular plate having an outer peripheral portion 6b orthogonal to the tube axis and an inner peripheral portion 6c bulging from the portion 6b in a hemispherical shape. The inner peripheral edge of 6c is welded to the end of the upstream exhaust pipe 4
Has been done. A plurality of screw holes 6d ... Are formed in the outer peripheral portion 6b at equal intervals in the circumferential direction. The downstream flange 7 is press-molded into an annular plate body having an outer peripheral portion 7b orthogonal to the tube axis and an inner peripheral portion 7c recessed from the portion 7b in a hemispherical shape. The inner peripheral edge portion is welded 9 to the end portion of the downstream side exhaust pipe 5. A plurality of bolt insertion holes 7d ... Corresponding to the screw holes 6d are formed in the outer peripheral portion 7b. In addition, each flange 6,
Reinforcing annular flanges 6e, 7e are formed on the outer peripheral edge of the member 7.

As shown in FIG. 1, the two flanges 6 and 7 have a hemispherical sealing surface 6 which is an opposing surface of the inner peripheral portions 6c and 7c.
With the spiral gasket 1 interposed between a and 7a,
Each bolt 1 into which a conical coil spring 10 is inserted
By screwing 1 into the screw hole 6d from the bolt insertion hole 7d, it is fastened relatively movable within a predetermined range. In addition, both seal surfaces 6a and 7a normally have parallel hemispherical shapes.

The spiral gasket 1 is, as shown in FIG.
The flat hoop-shaped metal hoop 2 and the tape-shaped filler 3 are spirally polymerized and integrated with each other, and by applying an external force in the axial direction, a slip occurs between the two and the axial direction. It is configured so that it can be deformed into a telescope shape and the seal surface contact surfaces 1a and 1b, which are the gasket end surfaces, can be changed into hemispherical shapes corresponding to the seal surfaces 6a and 7a.

The hoop 2 is made of a thin metal plate material such as stainless steel. The hoop 2 is longer than the filler 3, and includes a winding start portion 2a and a winding end portion 2b.
As shown in FIG. 2, it is wound a plurality of times and spot-welded at a plurality of places. In addition, the hoop end portions 2a and 2b
The number of turns is mainly that the rigidity in the axial direction of the gasket 1 is sufficiently obtained in relation to the tightening surface pressure, and that the filler 3 is reduced in diameter so as to be compressed when it is deformed in the axial direction as described later. It is appropriately set on the condition that it is possible.

The filler 3 is one or more kinds of sheet material selected from inorganic paper, expanded graphite sheet in which expanded graphite particles are collectively formed, porous tetrafluoride ethylene resin sheet made porous by stretching, and mica sheet. It is configured.
In particular, as the above-mentioned inorganic paper, 36.5% by weight or more of fibrous material (ceramic fiber 5 to 20% by weight, sepiolite (alpha type having a fiber diameter of about 0.2 μm is preferable) 13.5 to 25 1% by weight of organic fiber hemp, such as pulp
10% by weight and 59% by weight or less (more preferably 4% by weight)
5.5-59% by weight) talc mineral, calcium carbonate,
Inorganic powder such as clay and barium sulfate, and 1-10% by weight
Preferred are those composed of natural rubber latex, synthetic rubber latex, and binder such as resin emulsion.

The width a of the filler 3 is set to be slightly wider than the width b of the hoop 2, so that the hoop 2 is attached to the seal surface contact surfaces 1a and 1b even when the filler 3 is deformed into a telescope shape according to the shape of the flange seal surface. Is not exposed (see Fig. 2). By the way, if the amount of protrusion (fluff amount) of the filler 3 from the hoop 2 is too small, the hoop 2 may come into contact with the flange sealing surface, and the hoop contact portion may form a leak path. If the amount of protrusion of the filler 3 is too large, the fluffing portion of the filler 3 may fall off due to the sealed fluid pressure, high-temperature vibration, or the like, and in any case a good sealing function cannot be expected. Therefore, it is necessary to determine the dimensions of both a and b in consideration of such a point, and in general, the seals such as the shapes of the flange seal surfaces 6a and 7a are in the range of 1 <a / b ≦ 1.5. It is preferable to decide according to the conditions.

The constituent materials and thicknesses of the hoop 2 and the filler 3 are appropriately selected according to the conditions such as the gasket diameter and the properties of the sealed fluid.

In the automobile exhaust pipe flange joint structure configured as described above, the spiral gasket 1 manufactured in the form in which both end surfaces 1a and 1b are flat (hereinafter referred to as "flat form") is used. When it is inserted between the sealing surfaces 6a and 7a and the flanges 6 and 7 are tightened with the bolts 11 ..., The gasket 1 slides and deforms in the axial direction by the tightening force of the coil springs 10 ... The surface contact surfaces 1a and 1b are changed into hemispherical shapes corresponding to the seal surfaces 6a and 7a, and finally, as shown in FIG. 2, they are brought into full contact with the seal surfaces 6a and 7a. . That is, the deformability and familiarity of the seal contact surfaces 1a and 1b to the seal surfaces 6a and 7a are extremely high. Moreover, when the gasket 1 is deformed in the axial direction,
Since the hoop 2 is deformed by the diameter reduction and the filler 3 is compressed in the radial direction, no gap is created between the hoop 2 and the filler 3, and the gasket density is improved.

Accordingly, the space between the flanges 6 and 7 can be satisfactorily sealed by the spiral gasket 1 with a low tightening pressure. The seal surface contact surface 1 of the spiral gasket 1
By forming the a and 1b and the sealing surfaces 6a and 7a in a hemispherical shape, even if there is a misalignment between the flanges 6 and 7, this is properly corrected. That is, when there is a misalignment, the spiral gasket 1 slides relatively on the hemispherical sealing surfaces 6a, 7a in the direction of the center as the bolts 11 are tightened. Will be corrected.

Since the flanges 6 and 7 are fastened relative to each other via the coil springs 10 ...
Even when the vibration of the exhaust pipe system is large as in the F car, the vibration is absorbed and relaxed by the action of the coil springs 10 ..., and an excessive load does not act on the flange fastening portion. Moreover, since the spiral gasket 1 is loaded between the flange sealing surfaces 6a and 7a having a hemispherical shape so as to be deformable in the axial direction, the parallelism of the flange sealing surfaces 6a and 7a is changed by the flange vibration. Sometimes,
It is possible to avoid the deterioration of the sealing performance due to the spiral gasket 1 being deformed accordingly.

By the way, the spiral gasket 1 can be used as it is in the flat form at the time of manufacture as described above, but if necessary, the seal surface contact surfaces 1a, 1b can be replaced with the flange seal surfaces 6a, 7a. The corresponding hemispherical shape (shape shown in FIG. 2) may be artificially or preformed by an appropriate pressure molding machine before use. The conditions for winding the hoop 2 and the filler 3 (winding tightening degree, etc.) are appropriately set according to the shape of the sealing surface, the presence or absence of preforming, etc., but further improvement of the sealing property is expected depending on the conditions. It

Further, as described above, when the flanges 6 and 7 are made of sheet metal and are welded to the exhaust pipes 4 and 5, the spiral gasket 1 can be deformed in the axial direction, and the sealing surface is The degree of freedom of 6a, 7a, etc. is increased, which is extremely advantageous in design and manufacture. Moreover, the weight of the exhaust pipe with a flange can be reduced as compared with the case where the flange is formed integrally with the exhaust pipe, so that the spiral gasket 1 is made of a high density molded body of expanded graphite in which a metal wire mesh is embedded. Combined with the fact that it is lighter than a general molded seal member, it is possible to realize a drastic weight reduction of the flange joint structure and thus the exhaust pipe system.

[0025]

As can be easily understood from the above description, according to the flange joint structure of the present invention, a good sealing function can be exhibited with a low tightening surface pressure. Moreover,
It is durable against vibration, can maintain a good sealing performance, and can sufficiently cope with the recent tendency toward FF.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a flange joint structure for an automobile exhaust pipe system according to the present invention.

FIG. 2 is a detailed view showing an enlarged main part of FIG.

FIG. 3 is a vertical cross-sectional side view of a main part showing a conventional structure, FIG. A showing a state before tightening of a spiral gasket, and FIG. B showing a state after tightening.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Spiral gasket, 1a, 1b ... Sealing surface contact surface (gasket end surface), 2 ... Hoop, 3 ... Filler, 4,
5 ... Exhaust pipe, 6, 7 ... Pipe end flange, 6a, 7a ... Flange sealing surface, 10 ... Coil spring (spring), 11 ... Fastening bolt.

Claims (1)

[Claims] 1. In a flange joint structure in which a spiral gasket is sandwiched between opposed pipe end flanges, the flange sealing surfaces, which are gasket clamping surfaces of both flanges, are formed in parallel hemispherical shapes, and the spiral gasket is formed. However, the flat hoop-shaped metal hoop and the tape-shaped filler are polymerized and integrated in a spiral shape so as to be deformable in the axial direction so that the gasket end surface has a hemispherical shape corresponding to the flange sealing surface. A flange joint structure for an automobile exhaust pipe system, characterized in that both flanges are fastened via a spring.