JP2001263054A - Exhaust pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To considerably improve assembling workability, to reduce costs, and to restrain defect with respect to a thermal stress. SOLUTION: An exhaust manifold comprises a main body 2 comprising an inner tube 5 and an outer tube 6 and a flange 3. The flange 3 is fixed by being fastened by a bolt in a state of being fixed by welding to a tip of the outer tube 6 and of being aligned with respect to a cylinder head 9 of an internal combustion engine. The inner tube 5 is integrally constituted and supported by a mesh member. Both edge sides of the inner tube 5 are free ends, and can expand in a longitudinal direction and a radial direction. A cap 12 for restraining the inner tube 5 from deviating exceeding a predetermined degree is provided to the flange 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 such as an exhaust manifold, and more particularly, to an exhaust pipe having a double pipe structure of an inner pipe and an outer pipe.

[0002]

2. Description of the Related Art Generally, an exhaust manifold is mounted on a cylinder head of an engine. Exhaust gas derived from a plurality of exhaust ports communicating with a plurality of cylinders of the engine is led to a so-called one exhaust pipe via an exhaust manifold.

[0003] The exhaust manifold generally comprises a manifold body and flanges provided at both ends thereof. Then, the flange portion on one end side is fastened and fixed to the cylinder head via a gasket with bolts. Further, the flange on the other end side is also fastened and fixed to the flange on the exhaust pipe side with bolts.

On the other hand, as a structure of the manifold body, there is a structure having a double pipe structure of an inner pipe and an outer pipe. In such a double-pipe structure, the outer pipe is provided at a predetermined distance from the inner pipe, and the edges of the inner pipe and the outer pipe are fixed to the flange by welding. .

[0005] However, when the both end edges of the inner tube formed integrally as a whole are fixed to the flange portion, there are the following problems. That is, the exhaust gas derived from the exhaust port is directly exposed to the inner peripheral surface of the inner pipe. For this reason, the inner tube is easily subjected to thermal stress, and cracks, deformation, and the like due to the thermal stress may occur.

In order to solve such a problem, it is conceivable to provide the inner tube with a stress relaxation structure. In this case, FIG.
As shown in FIG. 8, the inner pipe 51 of the exhaust manifold 50 is
It is constituted by a plurality of divided pipes 51a connected to each other. With such a configuration, even if thermal stress is generated due to the heat of the exhaust gas, sliding between the divided pipes 51a is allowed, so that the thermal stress is absorbed and relaxed, and thus cracks and deformation are prevented. Is achieved.

[0007]

However, the following problems are conceivable in the exhaust manifold according to the above-mentioned prior art. That is, since the inner pipe 51 must be constituted by the plurality of divided pipes 51a, the structure of the inner pipe 51 becomes complicated, and the work for assembling becomes complicated. As a result, the manufacturing cost of the exhaust manifold 50 increases.

[0008] Of the divided pipe 51a, the flange 5
The end portions on the sides 2 and 53 are fixed by welding to support the inner tube 51. In this case, since the inner pipe 51 (the divided pipe 51a) is generally thin (thickness: about 0.6 mm to 1.0 mm), thermal deterioration and deformation due to welding may occur in the welded portion. In addition, due to the property that the inner tube 51 is thin, it is difficult to set welding conditions. If the conditions are slightly deviated, there is a problem that a part of the inner tube 51 may be melted down or cracked. Can be

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and can dramatically improve the assembling workability, reduce the cost, and suppress the problem with the thermal stress. One of the main purposes is to provide exhaust pipes.

[0010]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, an inner pipe capable of leading exhaust gas from an upstream side to a downstream side, and an exhaust pipe located closer to an outer peripheral side than the inner pipe. In an exhaust pipe provided with an outer pipe provided and an attachment portion provided so as to extend at least in an outer peripheral direction at an edge of the outer pipe, at least one edge side of the inner pipe is a free end, and thermal stress is reduced. The gist of the invention is that it is configured to be able to expand and contract at least in the longitudinal direction.

According to the first aspect of the present invention, in the inner pipe provided on the inner peripheral side of the outer pipe, the exhaust gas can be led from the upstream side to the downstream side. In such an exhaust pipe,
At least one edge side of the inner tube is a free end, and even if thermal stress is applied to the inner tube based on increase and decrease of heat transmitted from the exhaust, the inner tube is free from thermal stress at least in the longitudinal direction. Can expand and contract. Therefore, even if the inner tube expands and contracts in the longitudinal direction, stress does not concentrate.
In this case, it is not necessary to divide the inner pipe more than necessary, and the inner pipe can be formed with a minimum number of members.

Further, in the invention according to claim 2,
An inner pipe capable of leading exhaust gas from an upstream side to a downstream side, an outer pipe provided on an outer peripheral side of the inner pipe, and a mounting portion provided at least in an outer peripheral direction at an edge of the outer pipe. The gist of the present invention is that at least one edge of the inner pipe is a free end, and the exhaust pipe is configured to be able to expand and contract at least in a radial direction with respect to thermal stress.

According to the second aspect of the present invention, in the inner pipe provided on the inner peripheral side of the outer pipe, the exhaust gas can be led from the upstream side to the downstream side. In such an exhaust pipe,
At least one edge side of the inner pipe is a free end, and even if thermal stress is applied to the inner pipe based on increase or decrease of heat transmitted from the exhaust, the inner pipe is free at least in the radial direction with respect to the thermal stress. Can expand and contract. Therefore, even if the inner tube expands and contracts in the radial direction, stress does not concentrate. In this case, it is not necessary to divide the inner pipe more than necessary, and the inner pipe can be formed with a minimum number of members.

Further, in the invention according to the third aspect, an inner pipe capable of leading exhaust gas from an upstream side to a downstream side, an outer pipe provided on an outer peripheral side of the inner pipe, An exhaust pipe having an attachment portion provided at least in an outer peripheral direction at an end edge, wherein at least one end side of the inner pipe is a free end, and is capable of expanding and contracting at least in a longitudinal direction and a radial direction with respect to thermal stress. The main point is that

According to the third aspect of the present invention, in the inner pipe provided on the inner peripheral side of the outer pipe, the exhaust gas can be led from the upstream side to the downstream side. In such an exhaust pipe,
At least one edge side of the inner pipe is a free end, and even if thermal stress is applied to the inner pipe based on increase or decrease of heat transmitted from the exhaust, the inner pipe is at least in the longitudinal direction and the diameter with respect to the thermal stress. It can expand and contract freely in any direction. For this reason, even if the inner tube expands and contracts in the longitudinal direction or the radial direction, stress does not concentrate. In this case, it is not necessary to divide the inner pipe more than necessary, and the inner pipe can be formed with a minimum number of members.

In addition, according to the invention described in claim 4, in the exhaust pipe according to any one of claims 1 to 3, a clearance is provided between the inner pipe and the outer pipe, and the one end edge side is provided. The gist of the invention is that a clearance is provided at a predetermined part except for the clearance, and a support member for supporting the inner tube is provided.

According to the fourth aspect of the present invention, in addition to the functions of the first to third aspects, the inner pipe is supported by the support member, and the inner pipe and the outer pipe are interposed between the inner pipe and the outer pipe. Rattle is prevented.

[0018] In addition, in the invention according to claim 5, in the exhaust pipe according to any one of claims 1 to 4, at least one edge of the outer pipe and at least one of the mounting portions are provided with the inner pipe. The gist of the present invention is that a deviation suppressing means for suppressing a deviation exceeding a predetermined value is provided.

According to the fifth aspect of the present invention, in addition to the functions of the first to fourth aspects of the present invention, deviation control provided on at least one of the edge of the outer tube and at least one of the mounting portions is provided. By means, the deviation of the inner pipe beyond a predetermined level is suppressed. For this reason, work at the time of attachment of an exhaust pipe becomes easy, and a malfunction when expansion and contraction of the inner pipe occurs excessively during use can be suppressed.

According to a sixth aspect of the present invention, in the exhaust pipe according to the fifth aspect, the deviation suppressing means is provided at a tip of the inner pipe so as to suppress a deviation of the inner pipe in a longitudinal direction. The gist of the present invention is to provide a ring portion which is opposed to and is provided at a predetermined interval.

According to the sixth aspect of the present invention, in addition to the function of the fifth aspect of the present invention, the deviation of the inner tube in the longitudinal direction is suppressed by the ring portion of the deviation suppressing means.

Further, according to the invention described in claim 7, in the exhaust pipe described in claim 6, the deviation suppressing means further includes a departure from the inner pipe so as to suppress a deviation of the inner pipe in a radial direction. The gist of the invention is that an inner pipe guide portion extending in a direction intersecting with the ring portion is provided inside.

According to the seventh aspect of the present invention, in addition to the function of the sixth aspect of the present invention, the inner pipe guide portion extending in the direction intersecting with the ring portion prevents the inner pipe from deviating in the radial direction. Is suppressed.

In addition, in the invention according to the eighth aspect, in the exhaust pipe according to the seventh aspect, a predetermined clearance is formed at least between the inner pipe guide portion and the inner pipe in a cold state. The gist is that it is configured to be executed.

According to the eighth aspect of the present invention, in addition to the function of the seventh aspect of the present invention, since there is a clearance between the inner pipe guide portion and the inner pipe at the time of cold,
At the time of hot, deformation due to the thermal stress of the inner pipe is allowed to some extent, and deformation exceeding a predetermined level is regulated by the presence of the inner pipe guide portion.

In addition, according to the ninth aspect of the present invention, in the exhaust pipe according to any one of the fifth to eighth aspects, the mounting portion is mounted in a state facing a predetermined mating member via a gasket. The gist is that the deviation suppressing means is constituted by a part of a gasket.

According to the ninth aspect of the present invention, in addition to the functions of the fifth to eighth aspects, the space between the mounting portion and the mating member is sealed by the gasket. In the present invention, since the departure suppression means is constituted by a part of the gasket, it is not necessary to separately provide the departure suppression means.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment will be described below with reference to FIGS.

As shown in FIGS. 1 and 2, an exhaust manifold 1 as an exhaust pipe includes a main body 2 and flanges 3 and 4 as mounting parts. The main body 2 includes an inner tube 5 made of stainless steel and an outer tube 6 made of stainless steel located around the inner tube 5 with a predetermined gap (clearance) therebetween.

The flange portions 3 and 4 are made of an iron material and are fixed by welding to the tip of the outer tube 6 (see FIGS. 2 and 4). A plurality of bolt holes 7, 8 are formed in the flange portions 3, 4. And one flange part 3
Is aligned with a cylinder head 9 of an internal combustion engine (for example, an automobile engine) as a mating member, and
The gasket 10 is interposed between the two 3 and 9 and fastened and fixed by bolts (not shown). The other flange portion 4 is fastened and fixed by a bolt (not shown) in a state of being aligned with a flange portion of an exhaust pipe (not shown) as a mating member.

The main body 2 has a plurality of (four in the figure) corresponding to the respective exhaust ports 11 of the cylinder head 9 on one flange 3 side, and they are assembled on the downstream side to form the other. Are provided on the flange portion 4 side. Therefore, the exhaust gas generated in each combustion chamber of the internal combustion engine is discharged from the plurality of exhaust ports 11 to the exhaust manifold 1.
The exhaust gas is guided to the inside of each main body 2 (inside the inner pipe 5), and the exhaust gas is merged into one inner pipe 5 through the inner pipe 5, and then is led to the exhaust pipe. I have.

As shown in FIG. 3, the inner tube 5 is
(Thickness: 0.6 mm to 1.0 mm).
A stainless steel mesh member M constituting a support member is provided in the clearance between the outer tube 6 and the inner tube 5. Further, the inner pipe 5 is not a divided pipe as described in the related art, but is integrally formed.

Further, the outer tube 6 is composed of divided pieces 6a divided into two in the cross-sectional direction, and one outer tube 6 is formed by joining (for example, welding) joint portions 6b extending in a flange shape. Is configured.

Next, a characteristic portion of the present embodiment will be described. As described above, the inner tube 5 is supported by the mesh member M provided in the clearance between the inner tube 5 and the outer tube 6. As shown in FIGS. 2 and 4, both ends of the inner tube 5 are free ends. That is, since the inner pipe 5 is directly exposed to the exhaust gas discharged from the exhaust port 11, the inner pipe 5 is likely to be heated to a high temperature, and is likely to receive a heat history. In this case, the inner tube 5 expands and contracts in the longitudinal direction and the radial direction, but in order to allow such expansion and contraction freely, both end sides of the inner tube 5 have clearances in the longitudinal direction and the radial direction, respectively. are doing.

As shown in FIG. 2, the flange portion 3 is provided with a cap 12 as a deviation suppressing means for restricting the inner tube 5 from deviating more than a predetermined amount. The cap 12 includes an annular plate-shaped ring portion 13 and a cylindrical portion 14 as an inner tube guide extending from the inner peripheral edge of the ring portion 13 along the inner tube 5. The ring portion 13 is fixed to the flange portion 3 by spot welding or the like with the ring portion 13 positioned at a predetermined position. The outer diameter of the cylindrical portion 14 is smaller than the inner diameter of the inner pipe 5,
A predetermined clearance is formed between the cylindrical portion 14 and the inner pipe 5.

As shown in FIG. 4, the flange portion 4 is also provided with a cap 15 as a deviation suppressing means for suppressing a deviation of the inner pipe 5 beyond a predetermined value. The cap 15
Is also constituted by a ring portion 16 and a cylindrical portion 17.
The ring portion 16 is fixed to the flange portion 4 by spot welding or the like with the ring portion 16 being positioned at a predetermined position. In the figure, the outer diameter of the cylindrical portion 17 is
Since it is substantially the same as the through hole of the flange portion 4, the configuration may be such that the cylindrical portion 17 is fixed by being fitted into the through hole. As described above, the outer diameter of the cylindrical portion 17 is smaller than the inner diameter of the inner tube 5, and a predetermined clearance is formed between the cylindrical portion 17 and the inner tube 5.

According to the present embodiment configured as described above, since both ends of the inner tube 5 are free ends, heat is applied to the inner tube 5 based on the increase and decrease of the heat transmitted from the exhaust gas. Even if stress is applied, the inner tube 5 can freely expand and contract at least in the longitudinal direction and the radial direction with respect to thermal stress. Therefore, even if the inner tube 5 expands or contracts in the longitudinal direction or the radial direction, stress does not concentrate. For this reason, it is possible to suppress the occurrence of cracks or significant deformation in the inner pipe 5, and it is possible to prevent various problems caused thereby.

Further, the integrated inner pipe 5 can be used, and a conventional structure for connecting a plurality of divided pipes is not required. Therefore, the structure of the inner tube 5 does not become complicated, and the operation during manufacturing and assembly can be significantly simplified. Further, the manufacturing cost of the exhaust manifold 1 can be reduced.

Further, since the inner tube 5 is supported by the mesh member M provided in the clearance between the inner tube 5 and the outer tube 6, rattling between the inner tube 5 and the outer tube 6 is prevented. can do.

At the same time, the flanges 3 and 4 have caps 1
Since the two and 15 are provided, it is possible to suppress the deviation of the inner pipe 5 from a predetermined or more. Therefore, for example, when the exhaust manifold 1 is mounted on the cylinder head 9, the inner pipe 5 does not fall off, and the mounting operation is facilitated. Further, at the time of use, it is possible to suppress a problem in the case where the expansion and contraction of the inner tube 5 occurs beyond the degree.

In particular, the ring portion 1 of the caps 12, 15
The deviation of the inner tube 5 in the longitudinal direction can be suppressed by the portions 3 and 16, and the deviation of the inner tube 5 in the radial direction can be suppressed by the tubular portions 14 and 17. Furthermore, since a predetermined clearance is formed at least between the cylindrical portions 14 and 17 and the inner tube 5 at the time of cold, deformation due to thermal stress of the inner tube 5 is allowed to some extent at the time of hot. ,
In addition, when a deformation or the like exceeding a predetermined value can occur, the deformation or the like is regulated by the presence of the tubular portions 14 and 17.

It should be noted that the present invention is not limited to the contents described in the above embodiment, and may be implemented as follows, for example.

(A) In the above embodiment, the ring portion 1
3, 16 and caps 12 comprising cylindrical portions 14, 17,
Although 15 is used as the departure suppression means, as shown in FIG. 5, the departure suppression means may be constituted only by the ring plate 21 having no cylindrical portion. Even with such a configuration, the deviation of the inner tube 5 in the longitudinal direction can be suppressed.

(B) Further, the inner tube guide portion need not be cylindrical, and may be a single or plural rod-shaped or plate-shaped protruding pieces as long as the inner tube 5 can be supported at the inner end portion of the inner tube. May be used.

(C) The departure suppression means may be omitted. In particular, in a case where the inner tube 5 can be supported at a portion (intermediate portion) other than the longitudinal end side of the inner tube 5, even if the deviation suppressing means is omitted, no inconvenience occurs.

(D) Instead of providing the departure suppressing means separately, as shown in FIG. 6, the through hole of the gasket 22 interposed between the flange portion 3 and the cylinder head 9 is extended and bent. The ring portion 23 and the cylindrical portion 2
4 may be configured. As described above, when the departure suppressing means is constituted by a part of the gasket 22, there is no need to separately provide the departure suppressing means, and the number of parts can be further reduced.

(E) The method for attaching and fixing the deviation suppressing means is not particularly limited, and may be fixed by spot welding as in the above embodiment, or may be fixed by fitting. Moreover, you may fix with a screw etc. separately.

Further, as shown in FIG. 6, when the departure suppressing means is constituted by a part of the gasket 22, a protruding part 25 is formed on a part of the gasket 22, and the protruding part 25 is connected to the flange part. 3 and can be attached and fixed by enlarging the diameter of the front end portion.

(F) In the above embodiment, both ends on the upstream and downstream sides of the inner tube 5 are free ends, but only one end may be free ends.

(G) In the above embodiment, the inner pipe 5 is formed integrally, but may be formed by a plurality of divided pipes.
However, if you want to reduce the number of parts and assembly man-hours,
It is desirable to configure the inner tube 5 with as few points as possible.

(H) In the above embodiment, the present invention is embodied in the exhaust manifold 1. However, if the exhaust pipe has a dual structure of an inner pipe and an outer pipe, it is provided downstream of the exhaust manifold 1. The present invention can also be embodied in a so-called exhaust pipe. Also, besides, exhaust muffler,
When the exhaust port inside the turbocharger unit or the internal combustion engine has a double pipe structure, the present invention can be applied to such an exhaust port.

Further, creation of a further technical idea which can be understood from the above embodiment will be described.

(1) The exhaust pipe according to any one of the first to ninth aspects, wherein the inner pipe is integrally formed. According to the above configuration, it is possible to more reliably improve the assembly workability and reduce the cost.

(2) In the exhaust pipe according to any one of the first to ninth aspects and the supplementary note (1), the inner pipe is not in direct contact with the inner peripheral surface of the outer pipe. According to the above configuration, the heat from the inner tube is prevented from being directly transmitted to the outer tube.

[0055]

As described above in detail, according to the exhaust pipe of the present invention, it is possible to dramatically improve the assembling workability, to reduce the cost, and to suppress the problem due to the thermal stress. An excellent effect is achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an exhaust manifold according to an embodiment.

FIG. 2 is a cross-sectional view illustrating an attached state of one end of an exhaust manifold.

FIG. 3 is a cross-sectional view of a main body of the exhaust manifold.

FIG. 4 is a cross-sectional view showing the other end of the exhaust manifold.

FIG. 5 is a cross-sectional view showing a state of attachment of one end of an exhaust manifold according to another embodiment.

FIG. 6 is a cross-sectional view illustrating an attached state of one end of an exhaust manifold according to another embodiment.

FIG. 7 is a perspective view showing a conventional exhaust manifold.

FIG. 8 is a cross-sectional view partially showing an inner tube according to a conventional technique.

[Explanation of symbols]

1. Exhaust manifold as exhaust pipe 2. Body part
3, 4 ... Flange part as attachment part, 5 ... Inner pipe, 6 ... Outer pipe, 9 ... Cylinder head as mating member, 10 ... Gasket, 12, 15 ... Cap as departure suppression means,
13, 16: a ring portion, 14, 17: a cylindrical portion as an inner tube guide portion, 21: a ring plate as a deviation suppressing means, 22: a gasket, 23: a ring portion, 24: a cylindrical portion.

Claims (9)

[Claims] 1. An inner pipe capable of discharging exhaust gas from an upstream side to a downstream side, an outer pipe provided on an outer peripheral side with respect to the inner pipe, and provided so as to extend at least in an outer peripheral direction at an edge of the outer pipe. An exhaust pipe comprising: a mounting portion provided with at least one end of the inner pipe as a free end, and configured to be able to expand and contract at least in a longitudinal direction with respect to thermal stress. 2. An inner pipe capable of discharging exhaust gas from an upstream side to a downstream side, an outer pipe provided on an outer peripheral side of the inner pipe, and an outer pipe provided at least at an outer peripheral edge at an edge of the outer pipe. An exhaust pipe provided with a mounting portion, wherein at least one edge of the inner pipe is a free end, and is configured to be able to expand and contract at least in a radial direction with respect to thermal stress. 3. An inner pipe capable of discharging exhaust gas from an upstream side to a downstream side, an outer pipe provided on an outer peripheral side of the inner pipe, and an outer pipe provided at least in an outer peripheral direction at an edge of the outer pipe. An exhaust pipe comprising: a mounting portion provided with at least one end of the inner pipe as a free end, and configured to be able to expand and contract at least in a longitudinal direction and a radial direction with respect to thermal stress. 4. A clearance is provided between the inner pipe and the outer pipe, and a support member for supporting the inner pipe is provided at a clearance at a predetermined portion except for the one end edge side. The exhaust pipe according to claim 1. 5. A departure suppressing means for restricting departure of the inner pipe by a predetermined amount or more is provided on at least one edge side of the outer pipe and at least one of the mounting portions. 4. The exhaust pipe according to any one of items 4. 6. The device according to claim 1, wherein the deviation suppressing means includes a ring portion provided at a predetermined distance from the distal end of the inner tube so as to suppress the deviation of the inner tube in a longitudinal direction. The exhaust pipe according to claim 5, characterized in that: 7. The departure suppressing means further includes an inner pipe guide part extending in a direction intersecting the ring part inside the inner pipe so as to suppress a deviation of the inner pipe in a radial direction. The exhaust pipe according to claim 6, wherein: 8. The exhaust pipe according to claim 7, wherein a predetermined clearance is formed at least between the inner pipe guide and the inner pipe in a cold state. 9. The device according to claim 1, wherein the mounting portion is mounted so as to face a predetermined mating member via a gasket, and the departure suppressing means is constituted by a part of the gasket. Item 9. An exhaust pipe according to any one of Items 5 to 8.