JP2001263056A - Joint structure of exhaust pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To considerably improve assembling workability and to provide an appropriate sealing characteristics in accordance with needs. SOLUTION: An exhaust mainfold 1 comprises a main body 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 being aligned with respect to a cylinder heat of an internal combustion engine. An edge part at an upstream side of the inner tube 5 at the flange 3 side is extendedly provided. and radially enlarging process is applied to the edge part. Further, an annular projection 12 is integrally formed to the radially enlarging part by press working. Accordingly, without using a gasket, the diameter enlarging edge part is interposed between the flange 3 and the cylinder head, and particularly at the projection 12, sealing is carried out between the flange 3 and the cylinder head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure of an exhaust pipe, and more particularly, to a joint structure of an exhaust pipe such as an exhaust manifold for extracting exhaust gas from an internal combustion engine.

[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.

[0004]

However, in such an exhaust manifold, the joining surface of the flange portion is brought into close contact with the cylinder head via a gasket, and in this state, a bolt is inserted through a bolt insertion hole and fastened by the bolt. Attach it to the engine. As described above, since a seal member called a gasket must be separately provided when attaching the exhaust manifold, the assembling work becomes extremely complicated, and the positional relationship between the cylinder head, the gasket, and the flange portion is adjusted when fastening the bolt. Work may be difficult.

Further, since one gasket is generally provided between the exhaust manifold and the cylinder head, the elastic modulus (for example, the spring constant) may be varied for each port or set to a desired value. Or it becomes difficult. For this reason, there is a possibility that it is practically impossible to appropriately set the sealing property for each corresponding exhaust port.
Further, when one gasket is arranged so as to surround all the exhaust ports, the sealing surface becomes inevitably large,
There was also a risk that the surface pressure associated with the bolt fastening would vary from site to site.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and can dramatically improve the assembling workability, and can exert an appropriate sealing performance according to needs. One of the main purposes is to provide a joint structure of an exhaust pipe.

[0007]

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. Joining of an exhaust pipe provided with an outer tube provided, and a mounting portion provided to extend at least in an outer peripheral direction at an end edge of the outer tube, wherein the mounting portion is mounted in a state facing a predetermined mating member. The inner pipe is extended between an end portion of the inner pipe and a diameter-expanding process so that the edge section is interposed between the mounting portion and the counterpart member. The gist of the invention is that the mounting portion and the mating member are configured to be sealed.

According to the first aspect of the present invention, the mounting portion provided at least in the outer peripheral direction at the edge of the outer tube provided on the outer peripheral side of the inner tube is opposed to the mating member. So that the exhaust pipe is
Joined to the mating member. Now, according to the present invention, the end portion of the inner pipe is extended and subjected to the diameter expansion processing, so that the end portion is interposed between the mounting portion and the mating member. Then, a seal is provided between the mounting portion and the mating member at the edge of the inner tube.
For this reason, when joining, there is no need to interpose a separate sealing member such as a gasket conventionally used. When there are a plurality of inner pipes, the space between the mounting portion and the mating member corresponding to each inner pipe is sealed. Therefore, it is also possible to set the seal surface pressure for each inner tube.

According to the second aspect of the present invention, in the exhaust pipe joining structure according to the first aspect, a ridge that can exhibit a sealing function is formed at an end portion of the inner pipe. That is the main point.

According to the second aspect of the invention, in addition to the operation of the first aspect of the invention, a sealing function is exerted by the ridge formed at the end of the inner tube. Therefore, when there are a plurality of inner tubes, the size of the ridge for each inner tube,
By appropriately setting the height, shape, and the like, it is possible to set the seal surface pressure for each inner tube.

Further, in the invention according to claim 3, in the exhaust pipe joining structure according to claim 2, the ridge is
The gist is that it is formed inside the outer circumference of the outer tube.

According to the third aspect of the present invention, in addition to the function of the second aspect of the present invention, since the ridge is formed inside the outer periphery of the outer tube, a seal is formed from the peripheral edge of the inner tube. Since the distance to the portion is relatively short, it is possible to prevent a temperature rise in the unnecessary portion due to the intrusion of the exhaust gas into an unnecessary portion, and a problem such as a thermal deformation associated therewith.

According to a fourth aspect of the present invention, in the joint structure of the exhaust pipe according to any one of the first to third aspects, the end of the inner pipe has a diameter-expanded tip end further. The gist of the invention is that it is formed by being bent or folded inward, and an elastic function is provided at the curved or folded portion.

According to the fourth aspect of the present invention, in addition to the effects of the first to third aspects, the distal end of the inner tube whose edge is enlarged in diameter is further bent or folded inward. Thus, an elastic function is provided in the curved or folded portion. Therefore, the sealing function can be exhibited with a relatively simple configuration. If there are multiple inner tubes,
By appropriately setting the curvature of the curved portion, the angle of the folded portion, and the like for each inner tube, it is possible to set the seal surface pressure for each inner tube.

In addition, in the invention according to claim 5, in the exhaust pipe joining structure according to any one of claims 1 to 4, the counterpart member is an internal combustion engine having a plurality of exhaust ports. The gist is that a pipe is provided corresponding to each of the exhaust ports.

According to the fifth aspect of the present invention, in addition to the effects of the first to fourth aspects, the mounting portion is exposed to a high temperature by the relatively high temperature exhaust gas discharged from the internal combustion engine. However, in this case, it is possible to set the seal surface pressure for each inner tube in consideration of thermal deformation of the mounting portion and the like.

Further, according to the invention described in claim 6,
The joint structure of the exhaust pipe according to any one of claims 1 to 5, wherein the gist is that the inner pipe is thinner than the outer pipe.

According to the sixth aspect of the present invention, since the inner pipe is thinner than the outer pipe, it is possible to easily perform various processings including the diameter expansion processing.

[0019]

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 has a main body 2 and flanges 3 and 4 as mounting parts. The main body 2 includes a stainless steel inner tube 5 and a stainless steel outer tube 6 located around the inner tube 5 with a predetermined gap 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 (FIG. 3).
reference). A plurality of bolt holes 7, 8 are formed in the flange portions 3, 4.
Are formed. One of the flange portions 3 is an internal combustion engine (for example, an automobile engine) 9 as a mating member.
With the cylinder head 10 aligned with
It is fastened and fixed by bolts 11. 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).

The main body 2 is composed of a plurality of (four in the figure) corresponding to each exhaust port of the internal combustion engine 9 on one flange 3 side, and they are assembled on the downstream side to form the other. The number is one on the flange portion 4 side. Therefore, the exhaust gas generated in each combustion chamber of the internal combustion engine 9 is guided from each of the plurality of exhaust ports into each main body 2 of the exhaust manifold 1 (inside the inner pipe 5), and the exhaust gas passes through the inner pipe 5. After merging with one inner pipe 5, it is led to the exhaust pipe.

The inner pipe 5 is formed to be thinner than the outer pipe 6, and a stainless steel mesh member (not shown) is provided in a gap between the outer pipe 6 and the inner pipe 5. Further, the inner pipe 5 is constituted by a plurality of divided pipes connected to each other, so that even if a thermal stress due to the heat of the exhaust gas is generated, the thermal stress is absorbed and relaxed, and as a result, cracks, deformation, etc. The occurrence is prevented. Needless to say, the inner pipe may be an integral pipe instead of the split pipe.

Next, a characteristic portion of the present embodiment will be described. In the present embodiment, a gasket that is separately provided conventionally is not provided between the flange portion 3 and the cylinder head 10. More specifically, as shown in FIG. 3, the upstream end of the inner pipe 5 on the flange portion 3 side (upstream side) is extended, and the portion is subjected to a diameter expansion process (flare process). Have been. Further, the enlarged diameter portion is subjected to press working so that the annular ridge 12 is formed.
Are integrally formed. Therefore, the enlarged-diameter end portion is interposed between the flange portion 3 and the cylinder head 10, and the flange portion 3 and the cylinder head 10 are sealed at the enlarged-diameter edge portion, particularly, the ridge 12. It has become so. The ridge 12 is formed so as to be located inside the outer periphery of the outer tube 6.

According to the present embodiment configured as described above, the upstream end of the inner pipe 5 is extended and the diameter thereof is expanded, so that the end is formed by the flange 3. And between the cylinder head 10. Then, an end portion of the inner tube 5, mainly the ridge 12, seals between the flange portion 3 and the cylinder head 10. For this reason, when joining
There is no need to provide a separate sealing member such as a gasket used conventionally. Therefore, the exhaust manifold 1
When mounting the bolts, the assembling work becomes extremely simple.
Since it is only necessary to perform the alignment between the
Work can be done easily. In addition, since the gasket does not need to be separately used, the cost of the entire exhaust device can be reduced.

Also, an edge (a ridge 12) is provided for each inner tube 5.
By appropriately setting the shape, height, size, and the like, the spring constant and the amount of displacement can be freely set as appropriate. For this reason, it is possible to suppress occurrence of unexpected variation in surface pressure for each port, and it is possible to secure an appropriate sealing surface pressure corresponding to each port. In addition, a suitable spring constant is 10 N / mm or more and 500 N / mm or less, and more preferably 50 N / mm or more and 200 N / mm.
Or less, more preferably 80 N / mm or more and 150 or more.
N / mm or less.

Furthermore, since the ridge 12 is formed inside the outer periphery of the outer tube 6, the distance from the peripheral edge of the inner tube 5 to the portion to be actually sealed is relatively short, and the high-temperature exhaust gas is not covered by the flange. There is no chance of the part 3 getting into the outer peripheral side. Therefore, it is possible to prevent a temperature rise in the outer peripheral side portion of the flange portion 3 and the accompanying problems such as thermal deformation.

At the same time, since the inner tube 5 is thinner than the outer tube 6, the above-mentioned flaring and press working can be easily performed, thereby shortening the working time and improving the production efficiency. Can be.

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

(A) In the above embodiment, the ridges 12 having a curved cross section are employed. However, any shape may be used as long as the edge of the inner tube 5 can exhibit a sealing function. For example, a ridge 13 having a V-shaped cross section as shown in FIG. 4A, a ridge 14 having a trapezoidal cross section as shown in FIG. Further, as shown in FIG. 4C, a double (multiple) ridge 15 can be employed so as to provide a double (multiple) seal structure.

(B) In the above embodiment, the upstream end of the inner tube 5 is extended, and the portion is expanded (flare processing).
Then, the ridge 12 is formed by pressing the enlarged diameter portion, and the flange 12 and the cylinder head 10 are sealed at the ridge 12. On the other hand, as shown in FIG. 5, the end portion of the inner tube 5 is enlarged in diameter and the enlarged end portion is folded back further inward.
It may be 6. Even with such a configuration, the sealing portion 1
6, the elastic function is exhibited, and the same operation and effect as those of the above embodiment can be obtained. In addition, the sealing function can be exhibited with a relatively simple configuration, and the processing becomes easy. Further, by appropriately setting the angle of the folded portion and the like for each inner tube 5, it is also possible to set the seal surface pressure for each inner tube 5.

(C) Further, instead of the folded shape of (b), a curved shape may be used. According to the above configuration,
Since the concentration of stress can be distributed more than the folded shape,
The sealing performance can be exhibited for a longer period.

(D) Flange part 3 as mounting part
May be provided so as to extend at least in the outer peripheral direction at the edge of the outer tube, and may be configured to bend toward the inner tube 5 as shown in FIG. 5, for example.

(D) In the above embodiment, the flange portion 3 and the cylinder head 10
The space is sealed. On the other hand, a configuration may be adopted in which the downstream side of the inner pipe 5 is extended and the extended portion seals between the flange portion 4 and the flange portion of the exhaust pipe.

(E) In the above embodiment, the present invention is embodied in the exhaust manifold 1. However, the present invention is also applicable to a so-called exhaust pipe as long as the exhaust pipe has a double structure of an inner pipe and an outer pipe. It can also be converted.

(F) Although not particularly mentioned in the above embodiment, a configuration in which the inner tube 5 is fixed (welded and fixed) to the flange portions 3 and 4 and the outer tube 6 may be adopted.

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

(1) The exhaust pipe joining structure according to claim 2, wherein the ridge has a multiple annular structure. According to the above configuration,
The sealing performance can be more reliably exhibited. The configuration of the supplementary note (1) can be applied to the exhaust pipe joining structure according to claims 3 to 6.

(2) In the exhaust pipe joining structure according to any one of (1) to (6) and (1), the attachment portion is attached to the mating member by bolts. A joint structure for an exhaust pipe, characterized in that:
According to the above configuration, the above-described operation and effect are exerted in the bolt-fastened state.

[0040]

As described above in detail, according to the exhaust pipe joining structure of the present invention, it is possible to dramatically improve the assembling workability, and to achieve an appropriate sealing performance according to needs. It has an excellent effect that it can be demonstrated.

[Brief description of the drawings]

FIG. 1 is a side view showing an attached state of an exhaust manifold according to one embodiment.

FIG. 2 is a perspective view showing an exhaust manifold.

FIG. 3 is a partial cross-sectional view showing an upstream side of an exhaust manifold.

FIG. 4 is a partial cross-sectional view showing a distal end shape of an inner tube according to another embodiment.

FIG. 5 is a partial cross-sectional view showing an upstream side of an exhaust manifold according to another embodiment.

[Explanation of symbols]

1. Exhaust manifold as exhaust pipe 2. Body part, 3
... Flange part as attachment part, 5 ... Inner pipe, 6 ... Outer pipe, 9
... an internal combustion engine, 10 ... a cylinder head as a mating member,
11 ... bolt, 12 ... ridge.

Claims (6)

[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. And a mounting portion attached to the exhaust pipe, wherein the mounting portion is mounted in a state facing the predetermined mating member, and the edge of the inner pipe is extended to expand the diameter of the inner pipe. By doing
The exhaust pipe according to claim 1, wherein the end portion is interposed between the mounting portion and the mating member, and the end portion of the inner pipe is sealed between the mounting portion and the mating member. Joint structure. 2. The exhaust pipe joining structure according to claim 1, wherein a ridge that can exhibit a sealing function is formed at an end portion of the inner pipe. 3. The exhaust pipe joining structure according to claim 2, wherein the ridge is formed inside an outer periphery of the outer pipe. 4. An end portion of the inner pipe is formed by further bending or folding an end of the inner pipe whose diameter has been expanded, and an elastic function is provided at the curved or folded portion. The exhaust pipe joining structure according to claim 1. 5. The apparatus according to claim 1, wherein the partner member is an internal combustion engine having a plurality of exhaust ports, and the inner pipe is provided corresponding to each of the exhaust ports. The joining structure of the described exhaust pipe. 6. The exhaust pipe joining structure according to claim 1, wherein the inner pipe is thinner than the outer pipe.