JP2002349258A - Exhaust pipe flange joint structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust pipe flange joint structure which can uniformize seal bearing pressure and secure sealing performance in the exhaust pipe flange joint structure which holds a gasket between flanges and tightens it with a bolt. SOLUTION: This exhaust pipe flange joint structure is characterized in that a gasket 5 is arranged closer to a center hole 3 on a flange face 2 and it is tightened by a bolt inserted through a bolt hole 4 provided outward than the gasket location, and a recess-state camber 7 is formed on the flange face 2 in the direction Y crossing the direction X connecting the bolt holes 4 to each other or in the direction Y crossing the direction X connecting the bolt hole 3 to the center hole 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust pipe flange joint structure for connecting an exhaust pipe of a vehicle to an exhaust pipe or connecting an exhaust pipe to an exhaust manifold.

[0002]

2. Description of the Related Art Exhaust pipes of vehicles are connected at a plurality of locations by flange joints. As shown in FIGS. 9 and 10, a conventional exhaust pipe flange joint structure is such that flanges 11 each having a deformed cross section (a cross section different from a plate-shaped cross section) formed by press molding are formed in a concave shape from a central hole between flange surfaces 12. The gasket is disposed on the gasket holding portion 13, and the gasket is configured to be tightened with a bolt inserted into a bolt hole 14 provided outside the gasket arrangement portion. Incidentally, Japanese Patent Application Laid-Open No. 4-295127
Japanese Patent Application Laid-Open Publication No. H11-163873 proposes a flange joint structure of an exhaust manifold, in which a concave warp is formed on a flange surface in a direction connecting a bolt hole, so that a flange surface pressure can be made uniform when bolts are tightened. .

[0003]

However, FIG. 9 and FIG.
In the exhaust pipe flange joint structure, when a bolt fastening force is applied, as shown in FIG. 11, the flange surface is opposed to the opposite flange in a direction orthogonal to the direction connecting the bolt holes at the center of the direction connecting the bolt holes by the gasket surface pressure. There is a problem that the gasket is deformed in a convex shape to form a mouth opening portion 15 and the sealing surface pressure of the gasket becomes non-uniform, which may cause gas leakage.
Further, as in Japanese Patent Application Laid-Open No. 4-295127, even if a concave warp is formed in the direction connecting the bolt holes on the flange surface,
Since the direction of deformation occurring on the flange surface of the flange joint structure shown in FIGS. 9 and 10 is orthogonal to the direction of deformation described in JP-A-4-295127, there is no effect of preventing deformation of the flange surface. An object of the present invention is to provide an exhaust pipe flange joint structure in which a gasket is clamped between flanges with scissor bolts, whereby the seal surface pressure can be made uniform and sealing performance can be ensured.

[0004]

The present invention to achieve the above object is as follows. An exhaust pipe flange joint structure in which a gasket is disposed near a center hole of a flange surface and tightened with a bolt inserted into a bolt hole provided outside the gasket arrangement portion, and a direction in which the bolt holes are connected to the flange surface. An exhaust pipe flange joint structure in which a concave warp is formed in a direction perpendicular to the direction of the vertical axis or in a direction perpendicular to the direction connecting the bolt hole and the center hole.

[0005] In the exhaust pipe flange joint structure of the present invention, between the bolt holes on the flange surface or between the bolt holes and the center hole, in the direction orthogonal to the direction connecting the bolt holes or in the direction connecting the bolt hole and the center hole. Since the concave warp is formed in advance in the direction orthogonal to the direction, the flange receives the gasket surface pressure at the time of bolt fastening, and is orthogonal to the direction connecting the bolt hole or orthogonal to the direction connecting the bolt hole and the center hole. Direction, the convex deformation and the concave warp cancel each other out, and the opening of the flange is not deformed, and the sealing surface pressure of the gasket becomes uniform. As a result, the sealing property is ensured.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An exhaust pipe flange joint structure according to a preferred embodiment of the present invention will be described with reference to the drawings. 1 to 6 relate to the first embodiment of the present invention, FIG. 7 relates to the second embodiment of the present invention, and FIG. 8 relates to the third embodiment of the present invention.
Parts that are common or similar throughout all embodiments of the present invention are given the same reference numerals throughout all embodiments of the present invention.

First, the configuration and operation of a portion common or similar to all embodiments of the present invention will be described.
In the flange joint structure of the present invention, a gasket 5 is arranged in a portion of a flange surface 2 of a flange 1 near a center hole 3, and an exhaust pipe flange tightened with a bolt 6 inserted into a bolt hole 4 provided outside the gasket 5 arrangement portion. A joint structure,
On the flange surface 2, between the bolt holes 4 or between the bolt holes and the center hole 3, in the direction Y orthogonal to the direction X connecting the bolt holes 4, or orthogonal to the direction X connecting the bolt holes 4 and the center hole 3. In the direction Y, a concave (concave away from the opposing flange) warp (curve) 7 is formed.

The flange 1 has an irregular cross section (a cross section having a shape different from a plate shape). The flange 1 has a flange surface 2 having a concave portion 8 in which a gasket 5 is disposed near a center hole 3, and an axially extending portion that is bent at a right angle to the flange surface 2 at an inner peripheral portion of the flange surface 2 and away from the opposing flange. An axially extending portion 9 extending in the axial direction, and an axially extending portion 10 which is bent at a right angle to the flange surface 2 at an outer peripheral portion of the flange surface 2 and extends in the axial direction in a direction away from the opposing flange.
And has a substantially U-shaped cross section. The exhaust pipe is inserted into the inner peripheral axial extension 9, and the entire circumference is arc welded at the inner peripheral axial extension end to be joined to the flange 1.

In the case where the number of the bolt holes 4 is two, the flange 1 has a rhombus shape in which the direction connecting the bolt holes 4 is a long axis.
It has a shape in which a corner is rounded in an arc shape. When the number of the bolt holes 4 is n (= 3, 4), the flange 1 has an n-sided shape in which the corners are rounded in an arc shape. The gasket 5 is arranged between the concave portions 8 of the opposed flanges 1, and when the opposed flanges 1 are fastened with the bolts 6, the gasket 5 is pressed between the opposed concave portions 8 and compressed in the flange axial direction. Assuming that the deformation amount of the gasket 5 at the time of bolt tightening (the difference between the thickness of the gasket 5 before tightening and the thickness of the gasket 5 after tightening) is d, the gasket deformation amount for one flange is d / 2, and 1 The depth of the sled 7 formed on each of the flanges 1 is d / 2. In the vehicle exhaust pipe flange, when the number of the bolt holes 4 is 2, the depth d / 2 of the sled 7
Is about 1 mm.

Next, the operation of a portion common or similar to all the embodiments of the present invention will be described. A gasket 5 is arranged in the concave portion 8 between the opposed flanges 1, and the opposed flanges 1 are fastened with bolts 6 and nuts. At this time, the gasket 5 is sandwiched between the concave portions 8 and compressed, the flange 1 receives the gasket surface pressure (the surface pressure of the reaction force from the gasket), and the flange 1 is deformed in a U-shaped cross section. While deformed. At the bolts 6, the opposed flanges 1 are in contact with each other with pressure, but at the portions between the bolt holes 4, particularly at the central portions between the bolt holes 4, the flanges having a U-shaped cross section deformed when subjected to the gasket surface pressure. Due to the deformation, in the direction Y orthogonal to the direction X connecting the bolt holes 4,
Or, it deforms in a direction Y orthogonal to the direction X connecting the bolt hole 4 and the center hole 3 so as to protrude toward the opposed flange. However, since a concave warp 7 is formed in this portion in advance toward the opposed flange 1, the convex deformation of the flange due to the gasket surface pressure and the concave warp 7 cancel each other out, so that there is no flat surface. As a result, at the time of bolt fastening,
The surface pressure in the Y direction at the portion between the bolt holes 4 becomes uniform, and good sealing performance is secured. In addition, there is no gap between the bolt holes 4 of the flange 1 and gas leakage through the gap is also eliminated.

FIG. 6 shows a conventional press-shaped flange product with a deformed cross section (product without warpage) B, a conventional plate-shaped forged flange product C with a cross section,
It is a comparison result of the exhaust gas leakage test of the product A of the present invention (a press-formed cross-section flange product with a warp).
As is clear from FIG. 6, in the product of the present invention, there is no exhaust gas leakage, and a sealing performance equal to or higher than that of the conventional forged product C can be obtained.

Further, since the flange 1 can be joined with the uniform surface pressure via the gasket 5, the gasket 5 can be prevented from being crushed, the coupling rigidity between the flanges can be improved, and the variation in the vibration characteristics of the exhaust pipe can be reduced. Can be reduced. The fact that the sealing surface pressure of the gasket can be ensured without increasing the plate thickness of the flange 1 means that the flange plate thickness can be reduced when the sealing surface pressure is the same as the conventional one. When the plate thickness is reduced, it is possible to contribute to improvement of fuel efficiency and cost reduction by reducing vehicle weight.

Next, a configuration specific to each embodiment of the present invention,
The operation will be described. In Embodiment 1 of the present invention, as shown in FIGS. 1 to 6, the number of the bolt holes 4 is 2, and the flange shape is a rhombus shape in which corners are rounded in an arc shape. The sled 7 is formed at the center of the two bolt holes 4 (three central holes) and is formed in a concave shape in a direction Y orthogonal to a direction X connecting the bolt holes 4. The depth of the sled 7 is about 1 mm per one flange. Therefore, the total amount of warpage of the two opposed flanges 1 at the center of the center hole 3 is about 2 mm before the bolt is fastened. Regarding the operation, when the flange 1 is fastened with the bolts 6, the Y-direction sled 7
And the convex flange deformation due to the gasket surface pressure cancels out, so that the flange surface 2 becomes a plane in a direction orthogonal to the flange axis, the gasket surface pressure becomes uniform, and the conventional flange opening and exhaust gas leakage are eliminated. .

In a second embodiment of the present invention, as shown in FIG. 7, the number of the bolt holes 4 is three, and the flange shape is a rounded corner of a regular triangle. Sledge 7
At a position between each bolt hole 4 and the center hole 3, each bolt hole 4
And the center hole 3 is formed in a concave shape in a direction Y orthogonal to a direction X. Regarding the operation, the flange 1 is connected to the bolt 6
When the fastening is performed, the concave warpage 7 in the Y direction and the flange convex deformation due to the gasket surface pressure cancel each other out, and the flange surface 2 becomes flat in the direction Y perpendicular to the flange axis, and the gasket surface pressure becomes uniform, Conventional flange opening and exhaust gas leakage are eliminated.

In a third embodiment of the present invention, as shown in FIG. 8, the number of the bolt holes 4 is four, and the flange shape is a square, a rectangle, or a quadrilateral having a rounded parallelogram. It has become. The sled 7 is the flange surface 2
In addition, a portion between each bolt hole 4 and the center hole 3 is formed in a concave shape in a direction Y orthogonal to a direction X connecting each bolt hole 4 and the center hole 3. Regarding the operation, when the flange 1 is fastened with the bolt 6, the concave warpage 7 in the Y direction and the flange convex deformation due to the gasket surface pressure cancel each other out, so that the flange surface 2 has no uneven surface (perpendicular to the flange axis). (A plane in the plane), the gasket surface pressure becomes uniform, and the conventional flange opening and exhaust gas leakage are eliminated.

[0016]

According to the exhaust pipe flange joint structure of the first aspect, the concave shape is formed in the direction orthogonal to the direction connecting the bolt holes to the flange surface or in the direction orthogonal to the direction connecting the bolt holes and the center hole. Since the warp is formed in advance, the flange receives the gasket surface pressure at the time of bolt fastening, and faces the opposite flange in the direction orthogonal to the direction connecting the bolt holes or in the direction orthogonal to the direction connecting the bolt holes and the central hole. Even if it deforms into a convex shape, the convex deformation and the concave warp cancel each other out, the flange surface maintains a flat surface, the opening does not occur, and the sealing surface pressure of the gasket becomes uniform, which is favorable. A good sealing property can be secured.

[Brief description of the drawings]

FIG. 1 is a perspective view of an exhaust pipe flange joint structure according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line YY of FIG.

FIG. 3 is a half front view of the exhaust pipe flange joint structure according to the first embodiment of the present invention.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a sectional view taken along line BB of FIG. 3;

FIG. 6 is a graph showing a comparison of the leakage amount of the product of the present invention, a conventional press flange product, and a conventional forged flange product.

FIG. 7 is a perspective view of an exhaust pipe flange joint structure according to a second embodiment of the present invention.

FIG. 8 is a perspective view of an exhaust pipe flange joint structure according to a third embodiment of the present invention.

FIG. 9 is a perspective view of a conventional flange joint structure for a pressed product.

FIG. 10 is a sectional view taken along line AA of FIG. 9;

FIG. 11 is a perspective view showing a mouth opening in a conventional flange joint structure of a pressed product.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flange 2 Flange surface 3 Center hole 4 Bolt hole 5 Gasket 6 Bolt 7 Warp 8 Concave portion 9 Inner peripheral axial extension 10 External peripheral axial extension

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunori Wakatsuki 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yukito Sakai 1 Ochaya, Hashime-cho, Okazaki City, Aichi Prefecture Futaba Within Sangyo Co., Ltd. (72) Inventor Tetsuya Makino 1st Ochaya, Hashime-cho, Okazaki-shi, Aichi Futaba Sangyo Co., Ltd. F-term (reference) 3G004 AA01 BA00 DA01 DA11 DA21 GA00 3H016 AA02 AB07 AC01

Claims (1)

[Claims] An exhaust pipe flange joint structure in which a gasket is disposed near a center hole of a flange surface and tightened with a bolt inserted into a bolt hole provided outside a gasket arrangement portion, wherein a bolt is provided on the flange surface. An exhaust pipe flange joint structure in which a concave warp is formed in a direction orthogonal to a direction connecting holes or a direction orthogonal to a direction connecting a bolt hole and a center hole.