JP3331885B2 - Exhaust pipe for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust pipe for an internal combustion engine, and more particularly, to a structure of a dual exhaust pipe having a cross section divided into two by a partition plate.

[0002]

2. Description of the Related Art Conventionally, a pipe (commonly referred to as a .theta. Pipe) in which a cross section of a pipe body is divided into two by a partition plate welded to the pipe body is known from Japanese Utility Model Laid-Open No. 63-196425. . The θ pipe is connected to an exhaust manifold of an internal combustion engine of a vehicle via a spherical joint for isolating vibration, and is used for an exhaust pipe dual portion that bends in the middle and extends toward the rear of the vehicle to an intermediate position in the vehicle front-rear direction.

[0003]

However, the conventional exhaust pipe for an internal combustion engine has the following problems. The exhaust pipe has a bent part in the longitudinal direction. The part where the neutral surface of the bent part (the surface extending in the left-right direction of the vehicle passing through the center axis of the pipe body) intersects with the pipe body is when the pipe body is bent after welding of the partition plate and on a rough road after mounting the vehicle. This is the part where the largest cross-sectional deformation occurs when a bending load is applied at times. Further, the welded joint between the partition plate and the pipe main body is a part where the largest thermal stress is generated due to a difference in temperature between the partition plate and the pipe main body, and also a part where welding defects are likely to occur. In the past, the location where the neutral surface of the bent portion intersected the pipe body and the welded joint between the partition plate and the pipe body were aligned with each other, so severe conditions were increased and strength was improved. Was desired. The purpose of the present invention is
An object of the present invention is to provide an exhaust pipe for an internal combustion engine which is improved in strength in terms of bending deformation, thermal stress and the like.

[0004]

The present invention to achieve the above object is as follows. ( 1 ) A dual exhaust pipe for an internal combustion engine having a pipe main body having a bent portion in a longitudinal direction thereof and a partition plate which divides a cross section of the pipe main body into two and is welded to the pipe main body. The welded joint between the partition plate and the pipe body is shifted from the bending neutral surface of the bent portion of the pipe body, and the bending is performed from the intersection of the circle of the pipe body before deformation and the ellipse of the pipe body after deformation. Exhaust pipe for an internal combustion engine, located in a region away from the neutral plane. (2) Pipe body having a bend in the middle in the longitudinal direction
And the cross section of the pipe body is divided into two and welded to the pipe body
Dual exhaust for internal combustion engines having joined partitions
A pipe, wherein the partition plate has a bent portion of the pipe body.
Has a cross-sectional shape that crosses the neutral plane of the
The welded joint between the partition plate and the pipe body is
An exhaust for an internal combustion engine , wherein the partition plate is curved in a direction along the inner peripheral surface of the pipe main body in the vicinity of the inner peripheral surface of the pipe main body so as to be displaced from the neutral surface of the bent portion of the pipe main body. tube. (3) Pipe body having a bend in the middle in the longitudinal direction
And the cross section of the pipe body is divided into two and welded to the pipe body
Dual exhaust for internal combustion engines having joined partitions
A pipe, wherein the partition plate has a bent portion of the pipe body.
Has a cross-sectional shape that crosses the neutral plane of the
The welded joint between the partition plate and the pipe body is
Wherein the shifting from the neutral plane of bending of the bending portion of the flop body, the cross-sectional shape of the partition plate is S-shaped or inverse S-shaped
Exhaust pipe for an internal combustion engine. (4) the partition plate is curved in a direction along the inner peripheral surface of the pipe body in the vicinity of the inner peripheral surface of the pipe body (1) Symbol placement engine exhaust pipe. (5) the cross-sectional shape of the partition plate is S-shaped or inverse S-shape (1) Symbol placement engine exhaust pipe. ( 7 ) A dual exhaust pipe for an internal combustion engine, comprising: a pipe main body having a bent portion in a longitudinal direction thereof; and a partition plate formed by dividing a cross section of the pipe main body into two and welding and joining to the pipe main body. An exhaust pipe for an internal combustion engine, wherein the strength of a welded joint between a partition plate and a bent portion of the pipe body is greater than the strength of other welded joints. ( 7 ) A dual exhaust pipe for an internal combustion engine, comprising: a pipe main body having a bent portion in a longitudinal direction thereof; and a partition plate formed by dividing a cross section of the pipe main body into two and welding and joining to the pipe main body. The stiffness of the partition plate at the bent portion of the pipe body is reduced as compared with the stiffness of another portion, and the followability of the partition plate to the pipe body at the bent portion of the pipe body is increased as compared with the other portions. An exhaust pipe for an internal combustion engine.

In the exhaust pipes (1) to ( 5 ), since the neutral surface and the welded joint are displaced from each other, it is possible to prevent severe conditions from overlapping and to improve the strength. In the exhaust pipe of the above item ( 6 ), the strength of the welded joint at the bent portion is higher than the strength of the welded joint at the other portion, so that the strength of the welded joint is improved at the bent portion. In the exhaust pipe of the above ( 7 ), the rigidity of the partition plate at the bent portion of the pipe is made smaller than the rigidity of the partition plate at other portions, so that the partition plate can follow the deformation of the pipe cross section, and a large load is applied to the welded joint. And the welded joint is improved in strength.

[0006]

1 and 2 show an exhaust pipe for an internal combustion engine applicable to any of the embodiments of the present invention.
Represents an exhaust pipe for an internal combustion engine according to the first embodiment of the present invention,
FIG. 7 shows an exhaust pipe for an internal combustion engine according to a second embodiment of the present invention, and FIGS. 5 and 6 show an exhaust pipe for an internal combustion engine according to a third embodiment of the present invention. Portions common to all embodiments of the present invention are denoted by the same reference numerals throughout all embodiments of the present invention.

First, a structure common to all embodiments of the present invention will be described with reference to FIGS. The exhaust pipe 10 for an internal combustion engine of the present invention is composed of an exhaust pipe connected to an exhaust manifold of the internal combustion engine via, for example, a spherical joint for vibration isolation, and has a cross section of the pipe body 1 and the pipe body 1. And a partition plate 4 that is divided into two parts and welded to the pipe main body 1. The dual exhaust pipe is used for an internal combustion engine. The partition plate 4 extends curvedly or linearly in the diameter direction of the pipe main body 1, bends or bends in the direction along the inner peripheral surface of the pipe main body 1 in the vicinity of the inner peripheral surface of the pipe main body 1, and has a pipe at both ends. It extends along the inner peripheral surface of the main body 1 and is welded to the pipe main body 1 at that portion. 6 is a partition plate 4 and a pipe body 1
3 shows a welded joint with the above. This welded joint 6 extends continuously in the longitudinal direction of the exhaust pipe.

The dual exhaust pipe has a bent portion 11 which is bent substantially in the vertical plane in the middle of the longitudinal direction, extends obliquely downward from the connection portion to the exhaust manifold to the bent portion 11, and extends rearward at the bent portion 11 to the vehicle. Bend, bend 1
1 extends rearward from the vehicle 1 to an intermediate portion of the entire length of the vehicle. A single center pipe and a catalytic converter connected to the downstream side of the dual exhaust pipe are provided. Reference numeral 2 denotes a flange for connecting to an exhaust manifold, and 3 denotes a flange for connecting to a single center pipe, a catalytic converter, or the like.

Reference numeral 5 denotes a center line of the exhaust pipe, and a neutral plane of the bending (a plane including a neutral axis of the bending), which is one side from the neutral plane when a bending force is applied to the bent portion of the exhaust pipe by vibration or the like. Shows a plane in which a compressive stress is applied in the longitudinal direction of the exhaust pipe and a tensile stress acts in the longitudinal direction of the exhaust pipe on the other side, and a bending stress in the longitudinal direction of the exhaust pipe becomes zero on the neutral plane. As shown in FIG. 3, when a bending force is applied to the exhaust pipe in a vertical plane, the cross section of the exhaust pipe which has been circular until that time is deformed to approach an ellipse 1 ′ having the neutral surface 5 as a major axis. In the cross section, the pipe body undergoes a maximum displacement radially outward from the circle 1 at the neutral plane 5 at the intersection 12 between the neutral plane and the pipe body. The material is stainless steel for both the partition plate 4 and the pipe body 1.

Next, parts unique to each embodiment of the present invention will be described. In the first embodiment of the present invention, as shown in FIGS. 1 to 4, the partition plate 4 extends in the cross section direction in the bent section 11 of the pipe main body 1 in an inverted S-shape or S-shape in the cross-sectional direction. ing. In the bent portion 11 of the exhaust pipe 10, the position of the welded joint 6 between the pipe main body 1 and the partition plate 4 is shifted from the bent neutral surface 5 of the bent portion 11 of the pipe main body 1. In FIG. 3, the pipe body 1 before deformation
The cross-sectional shape of the pipe and the pipe body 1 when deformed
The intersection point P of the ellipse 1 'is a cross-sectional shape, substantially, is located on a line inclined by 45 degrees from the neutral plane shown in FIG. Then, the welded joint 6 is located in a region W (a region in the range of 90 degrees in FIG. 4) away from the neutral plane 5 from the intersection P.

In the operation of the first embodiment of the present invention, the pipe body 1 'in the deformed state pushes the partition plate 4 inward in the radial direction in the region W farther from the neutral plane 5 than the intersection point P, thereby welding and joining. No peeling force is applied to the portion 6, but the neutral surface 5 from the intersection P
In the side region, the deformed pipe body 1 ′ pulls the partition plate 4 outward in the radial direction, and a peeling force is applied to the welded joint 6. In the present invention, since the welded joint 6 is located in the region W, no peeling force (force in a direction in which the pipe body is separated from the partition plate) is applied to the welded joint 6, and the welding strength is improved.

In a second embodiment of the present invention, as shown in FIGS. 1, 2 and 7, the partition plate 4 and the bent portion 1 of the pipe body 1 are used.
The strength of the welded joint 6 with 1 is larger than the strength of the other welded joints. As a structure for increasing the strength of the welded joint 6 at the bent portion 11, for example, a slit is formed on the weld line in the bent portion 11 of the pipe body 1,
The slit is welded by welding using a welding rod to weld the pipe main body 1 and the partition plate 4, and the weld metal is raised from the outer peripheral surface of the pipe main body at the bent portion 11, and the welded joint 6 of the bent portion 11 is welded. There is a structure to increase the strength of the. However, it is not limited to this. Regarding the operation of the second embodiment of the present invention, the strength of the welded joint 6 is improved by building up the welded portion.

In the third embodiment of the present invention, as shown in FIGS. 1, 2, 5 and 6, the rigidity of the partition plate 4 at the bent portion 11 of the pipe main body is the same as the rigidity of other parts of the partition plate 4. Accordingly, the followability of the partition plate 4 to the pipe main body 1 in the bent portion 11 of the pipe main body is increased as compared with other portions. The upstream end of the partition plate 4 is a portion that receives a strong pulsating fluid force and has a relatively small temperature distribution (temperature difference between the partition plate 4 and the pipe body 1). Therefore, it is better that the thickness of the partition plate 4 is thicker from the viewpoint of withstanding exhaust pulsation, and even if the thickness of the partition plate is increased, the temperature difference between the partition plate 4 and the pipe body 1 is small. No large thermal stress is applied. For this reason, the thickness of the partition plate 4 is increased at the upstream end (the region 7 in FIG. 1) of the exhaust pipe 10.

However, the partition plate 4 extends over the entire length of the exhaust pipe.
If the thickness of the exhaust pipe is large, the rigidity of the partition plate 4 is too large at the bent portion 11 of the exhaust pipe, and excessive stress is generated in the pipe body 1, the partition plate 4, and the welded joint 6, so that at least the exhaust pipe is bent. In the portion 11, the rigidity of the partition plate 4 is reduced by making the sectional shape of the partition plate 4 into an S-shape or by making the thickness of the partition plate 4 thinner than other portions. In order to smoothly connect the thick portion of the partition plate 4 (region 7 in FIG. 1) and the thin portion of the partition plate 4 (region 9 including the bent portion 11 in FIG. 1), Part 8 following 7
In the above, the thickness of the partition plate 4 is gradually changed, and the thickness is reduced toward the downstream. For example, in FIG. 1, the thickness of the partition plate 4 is set to 1.5 to 2 mm in the region 7, and the thickness of the partition plate 4 is set to 0.5 to 2 mm in the region 9 (the region other than the region 7 and the region 8).
1.5 mm, and the thickness of the pipe main body 1 is the entire length (region 7,
0.8 to 2 mm over 8, 9). Regarding the operation of the third embodiment of the present invention, the exhaust pulsation resistance at the upstream end 7 of the partition plate 4 and the deformation followability to the pipe main body 1 at the bent portion 11 are compatible. By improving the deformation followability, the strength of the welded joint 6 at the bent portion 11 of the exhaust pipe is improved.

[0015]

According to the exhaust pipe for an internal combustion engine of the first to fifth aspects, the partition plate has a cross-sectional shape crossing the neutral surface of the bent portion of the pipe body, and is welded. Since the portion is shifted from the neutral surface of the bent portion of the bent portion of the exhaust pipe, an excessive tensile force is not applied to the welded joint, and the strength of the welded joint is improved. According to the exhaust pipe for an internal combustion engine of the sixth aspect , since the strength of the welded joint at the bent portion of the exhaust pipe is increased as compared with the other portions, the reliability of the welded portion at the end of the partition plate at the bent portion is improved. . According to the exhaust pipe for an internal combustion engine of the seventh aspect , since the rigidity of the partition plate is made smaller at the bent portion of the exhaust pipe than at other portions, an excessive load is hardly applied to the welded joint, and the strength of the welded joint is reduced. Is improved.

[Brief description of the drawings]

FIG. 1 is a side view of an exhaust pipe for an internal combustion engine applicable to any embodiment of the present invention.

FIG. 2 is a plan view of the exhaust pipe of FIG.

FIG. 3 is a cross-sectional view of a bent portion of the exhaust pipe according to the first embodiment of the present invention (thick members are indicated by a single line in the drawing).

FIG. 4 is a side view of the exhaust pipe showing a region where a welded joint exists in FIG. 4;

FIG. 5 is an exhaust pipe for an internal combustion engine according to a third embodiment of the present invention, and is a view as viewed from A in FIG. 1 (thick members are indicated by a single line in the drawing).

6 is an exhaust pipe for an internal combustion engine according to a third embodiment of the present invention, and is a view as viewed in a direction B in FIG. 1 (thick members are indicated by a single line in the figure).

FIG. 7 is a cross-sectional view of a bent portion of an exhaust pipe for an internal combustion engine according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 exhaust pipe 4 partition plate 5 neutral surface 6 welded joint 11 bent part

Claims (7)

(57) [Claims] 1. A dual exhaust pipe for an internal combustion engine, comprising: a pipe main body having a bent portion in a longitudinal direction thereof; and a partition plate formed by dividing a horizontal cross section of the pipe main body into two and being welded to the pipe main body. The welded joint between the partition plate and the pipe body is shifted from the neutral surface of the bent portion of the pipe body, and the intersection between the circle of the pipe body before deformation and the ellipse of the pipe body after deformation. An exhaust pipe for an internal combustion engine, which is located in a region apart from a neutral surface of the bending. 2. A pie having a bend in the middle of the longitudinal direction.
And the pipe body is divided into two sections.
For internal combustion engine having a partition plate welded to the surface
Exhaust pipe, wherein the partition plate has a curved pipe body.
It has a cross-sectional shape that crosses the neutral surface of the bend
In front of the weld joint between the partition plate and the pipe body.
Serial shift from the neutral plane of bending of the bent portion of the pipe body, for an internal combustion engine, characterized in that said partition plate is curved in a direction along the inner peripheral surface of the pipe body in the vicinity of the inner circumferential surface of the pipe body Exhaust pipe. 3. A pie having a bend in the middle of the longitudinal direction.
And the pipe body is divided into two sections.
For internal combustion engine having a partition plate welded to the surface
Exhaust pipe, wherein the partition plate has a curved pipe body.
It has a cross-sectional shape that crosses the neutral surface of the bend
In front of the weld joint between the partition plate and the pipe body.
Offset from the bending neutral plane of the bending portion of the serial pipe body, that the cross-sectional shape of the partition plate is S-shaped or inverse S-shaped
An exhaust pipe for an internal combustion engine. 4. The partition plate is curved in a direction along the inner peripheral surface of the pipe main body near the inner peripheral surface of the pipe main body.
Exhaust pipe 1 Symbol placement of the internal combustion engine. 5. The exhaust pipe for an internal combustion engine according to claim 1 Symbol placement sectional shape is S-shaped or inverse S-shaped of the partition plate. 6. A dual exhaust pipe for an internal combustion engine, comprising: a pipe main body having a bent portion in a longitudinal direction thereof; and a partition plate which divides a cross section of the pipe main body into two parts and is welded to the pipe main body. An exhaust pipe for an internal combustion engine, wherein the strength of a weld joint between the partition plate and the bent portion of the pipe body is greater than the strength of other weld joints. 7. A dual exhaust pipe for an internal combustion engine, comprising: a pipe main body having a bent portion in a longitudinal direction thereof; and a partition plate obtained by dividing a cross section of the pipe main body into two and welding and joining to the pipe main body. The rigidity of the partition plate at the bent portion of the pipe body is reduced as compared with the rigidity of another portion, and the followability of the partition plate to the pipe body at the bent portion of the pipe body is increased as compared with the other portions. An exhaust pipe for an internal combustion engine characterized by the above-mentioned.