JP2000248931A - Exhaust pipe for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust pipe for an internal combustion engine, allowing no welded portion to exist it any exhaust gas flowing path, capable of miniaturizing its cylinder head and its head flange. SOLUTION: An exhaust manifold 11 is formed into a duplex tube structure formed out of an external pipe 12, and of an internal pipe 13 passing through the inner side of the external pipe 12. In an area P1, the end part 12a of the external pipe 12 is welded to the hole 14 periphery of a head flange 14. The internal pipe 13 comes out of the end part 12a of the external pipe 12 to pass through the hole 14a of the head flange 14. The end part 13a of the internal pipe 13 is formed into a brim shape to let its brim shaped end part 13a be overlapped with the hole 14a circumference of the head flange 14. The brim shaped end part 13a of the internal pipe 13 is held between the head flange 14 and a gasket 15 to cause the internal pipe 13 to be thereby supported.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust pipe of an internal combustion engine having an exhaust manifold having a double pipe structure.

[0002]

2. Description of the Related Art A schematic structure of an exhaust pipe of this type is shown in FIG. In FIG. 4, the exhaust manifold 101 is
It has a double-pipe structure including an outer pipe 102 and an inner pipe 103 passing inside the outer pipe 102. The exhaust manifold 101 is connected to a head flange 104, and the head flange 104 is fastened to an end surface 106 a of a cylinder head 106 of the engine via a gasket 105.

In such a configuration, the exhaust gas of the engine is exhausted from each exhaust port 106b of the cylinder head 106, and the gasket 105 and the head flange 10 are discharged.
4 through each hole 104a.
1 flows into the inner pipe 103, and is further guided from the inner pipe 103 to an exhaust system (not shown). Exhaust manifold 1
Since 01 has a double tube structure, the exhaust gas is hardly cooled, and the catalyst temperature of the exhaust system can be maintained at a high temperature.

FIG. 5 shows an enlarged view of the connection structure between the exhaust manifold 101 and the head flange 104. As shown in FIG.
a, a step portion 111 is formed on the peripheral edge.
In 1, the outer tube 102 of the exhaust manifold 101
And the end of the inner tube 103 are arranged. Site P11
At the end, the end of the outer tube 102 and the head flange 104 are welded.
Are connected to each other to connect the exhaust manifold 101 to the head flange 104.

FIG. 6 shows an enlarged view of another connection structure between the exhaust manifold 101 and the head flange 104. As is apparent from FIG. 6, the inner diameter of the hole 104a of the head flange 104 is larger than the inner diameter of the exhaust port 106b. At the site P13, the end of the outer tube 102 and the head flange 104 are welded, and at the site P14, the outer tube 102 is welded.
Is welded to the end of the inner pipe 103, thereby connecting the exhaust manifold 101 to the head flange 104.

In each of the connection structures shown in FIGS. 5 and 6, the inner circumference of the exhaust port 106b and the inner circumference of the inner pipe 103 are linearly arranged, and there is no step in the inner circumference of the exhaust gas flow path. The resistance is getting smaller.

[0007]

However, in the above-mentioned conventional exhaust pipe, since the welding portion P12 in FIG. 5 and the welding portion P14 in FIG. 6 are in the flow path of the exhaust gas, spatter during welding remains. In some cases, this spatter mixes with the exhaust gas and enters the combustion chamber of the engine.

In particular, when using MiG welding, a large amount of spatter is generated, so that spatter cannot be completely removed even if spatter removal processing is performed after welding.
Spatter remains. In the case of using TiG welding, spatter hardly occurs, but the processing accuracy of the parts, that is, the outer pipe 102 of the exhaust manifold 101 is used.
In addition, the dimensional accuracy of the inner tube 103 and the dimensional accuracy of the head flange 104 are required, which leads to an increase in cost.

In the connection structure shown in FIG. 6, the inner diameter of the hole 104a of the head flange
Since the inner diameter of the gasket 105 is wider than the inner diameter of the gasket 105, the inner diameter of the hole 105a of the gasket 105 is also expanded. Therefore, gasket 1
05, the cylinder head 106
Therefore, the end face 106a and the head flange 104 have to be enlarged, and the miniaturization of the cylinder head 106 and the head flange 104 has been prevented.

In the connection structure shown in FIG. 5, since the step 111 is formed on the periphery of the hole 104a of the head flange 104, the inner diameter of the hole 105a of the gasket 105 does not need to be increased, but the strength of the step 111 is low. As a result, the gasket 105 cannot be strongly pressed against the end face 106a of the cylinder head 106 at the step portion 111.
As a result, similarly to the connection structure of FIG.
In order to secure the close contact area, the end face 106a of the cylinder head 106 and the head flange 104 have to be enlarged.

In view of the above, the present invention has been made in view of the above-mentioned conventional problems, and has no welding part in a flow path of exhaust gas and an exhaust pipe of an internal combustion engine capable of reducing the size of a cylinder head and a head flange. Is to provide.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, the present invention relates to a flange fastened to an end face of a cylinder head of an internal combustion engine via a gasket, and an exhaust manifold connected to the flange. An exhaust pipe for an internal combustion engine that guides exhaust gas exhausted from an exhaust port at an end face of the cylinder head to the exhaust manifold through a hole in the flange, wherein the exhaust manifold includes an outer pipe, and the outer pipe. An inner pipe passing through the inside of the inner pipe, wherein an end of the outer pipe is connected to a peripheral edge of a hole of the flange, and the inner pipe is penetrated through a hole of the flange to form an end of the inner pipe. The part is formed in a flange shape, and the end of the inner tube formed in the flange shape is overlapped with the flange and supported.

[0013] Here, the inner pipe is penetrated through the hole of the flange, and the end of the inner pipe formed in a flange shape is supported by being overlapped with the flange. Therefore, there is no welding portion for supporting the inner pipe, and the welding portion does not exist in the flow path of the exhaust gas. Also, when the inner diameter of the hole of the gasket is adjusted to the inner diameter of the inner pipe, the gasket is strongly sandwiched between the flanged end of the inner pipe and the end face of the cylinder head, and adheres tightly. Therefore, it is not necessary to increase the end face and the head flange of the cylinder head, and the cylinder head and the head flange can be reduced in size.

The present invention also provides a flange fastened to an end face of a cylinder head of an internal combustion engine via a gasket,
An exhaust manifold connected to the flange, wherein the exhaust manifold of the internal combustion engine guides exhaust gas exhausted from an exhaust port at an end face of the cylinder head to the exhaust manifold through a hole in the flange. Is a double pipe structure consisting of an outer pipe and an inner pipe passing through the inner side of the outer pipe, wherein a cylindrical portion is projected from the hole of the flange, and the periphery of the cylindrical portion of the flange is defined by the outer pipe. Connected to the end, penetrating the inner tube through the cylindrical portion of the flange, forming the end of the inner tube in a flange shape, and connecting the end of the inner tube formed in the flange shape to the flange. They are superimposed and supported.

Here, the inner pipe is penetrated through the cylindrical portion of the flange, and the end of the inner pipe formed in a flange shape is supported by being overlapped with the flange. Therefore, there is no welding portion for supporting the inner pipe, and the welding portion does not exist in the flow path of the exhaust gas. Also, when the inner diameter of the hole of the gasket is adjusted to the inner diameter of the inner pipe, the gasket is strongly sandwiched between the flanged end of the inner pipe and the end face of the cylinder head, and adheres tightly. There is no need to increase the size of the cylinder head and head flange.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a first example of an exhaust pipe of an internal combustion engine according to the present invention.
It is sectional drawing which shows embodiment. In FIG. 1, an exhaust manifold 11 has a double pipe structure including an outer pipe 12 and an inner pipe 13 passing inside the outer pipe 12. At the part P1, the end wall 12a of the outer tube 12 and the head flange 1
The periphery of the hole 14a is welded. Inner tube 13 is outer tube 1
2, and penetrates through the hole 14a of the head flange 14. An end portion 13a of the inner tube 13 is formed in a flange shape, and this flange end portion 13a is formed into a head flange 14a.
Around the hole 14a.

The gasket 15 is sandwiched between the head flange 14 and the end face 16a of the cylinder head 16, and between the flange end 13a of the inner tube 13 and the end face 16a.
A plurality of bolts (not shown) are passed through the head flange 14 around the hole 14a of the head flange 14, and the head flange 14 is pressed against the end face 16a of the cylinder head 16 via the gasket 15 by each of the bolts. I have. The flange 13a of the inner tube 13 is sandwiched between the head flange 14 and the gasket 15 to support the inner tube 13.

In the exhaust pipe of the first embodiment, the inner circumference of the exhaust port 16b of the cylinder head 16, the gasket 1
5, the periphery of the hole 15a and the inner periphery of the inner tube 13 are linearly arranged,
Since there is no step on the inner periphery of the exhaust gas flow path, exhaust resistance is reduced.

Further, there is no welding portion for supporting the inner pipe 13, and the welding portion does not exist in the flow path of the exhaust gas.
Therefore, the residual spatter due to welding does not mix into the exhaust gas and enter the combustion chamber of the engine.

Further, the gasket 15 is strongly sandwiched between the flange end 13a of the inner tube 13 and the end face 16a of the cylinder head 16 so as to be in close contact therewith. It is not necessary to increase the size of the head flange 14 and the cylinder head 16 and the head flange 14 can be reduced in size. Moreover, since the flange-shaped end 13a of the inner tube 13 is thin and has low rigidity, the airtightness is improved by the synergistic effect of the overlapping flange-shaped end 13a and the gasket 15.

Further, when compared with the conventional exhaust pipe shown in FIG.
Since a step on the peripheral edge of the hole of the head flange is not required and the processing of the head flange is easy, the cost can be reduced.

Further, since the outer pipe 12 of the exhaust manifold 11 does not contact the exhaust gas and only the inner pipe 13 contacts the exhaust gas, the heat of the exhaust gas is hardly conducted to the outer pipe 12,
The exhaust gas is hardly cooled, and the catalyst temperature of the exhaust system can be maintained at a high temperature.

FIG. 2 shows a second example of the exhaust pipe of the internal combustion engine according to the present invention.
It is sectional drawing which shows embodiment. In FIG. 2, the exhaust manifold 21 has a double tube structure including an outer tube 22 and an inner tube 23 passing through the inside of the outer tube 22. A cylindrical portion 24b is formed in the hole 24a of the head flange 24. At the portion P2, the end 22a of the outer tube 22 and the periphery of the tubular portion 24b of the head flange 24 are welded. The inner tube 23 passes through the inside of the tubular portion 24b of the head flange 24. The end 23a of the inner tube 23 is formed in a flange shape,
The flanged end 23a is overlapped with the head flange 24 around the hole 24a of the head flange 24.

The gasket 26 is sandwiched between the head flange 24 and the end face 27a of the cylinder head 27, and between the flanged end 23a of the inner tube 23 and the end face 27a.
A plurality of bolts (not shown) are passed through the head flange 24 around the hole 24a of the head flange 24, and the head flange 24 is pressed against the end face 27a of the cylinder head 27 via the gasket 26 by each of the bolts. I have. The flange 23a of the inner tube 23 is sandwiched between the head flange 24 and the gasket 26 to support the inner tube 23.

FIG. 3 shows an overall perspective view of the head flange 24. As is apparent from FIG. 3, the head flange 24 has a plurality of holes 24a, respective cylindrical portions 24b projecting from the respective holes 24a, and a plurality of holes 24c. Each hole 24a of the head flange 24 corresponds to each exhaust port 27b of the cylinder head 27, and exhaust gas from these exhaust ports 27b flows to the inner pipe 23 of the exhaust manifold 11 through each hole 24a. .
Each hole 24c of the head flange 24 is provided to pass a bolt for fixing the head flange 24.

The head flange 24 is formed by press-forming a thin steel plate. For this reason, compared with the head flange 14 of FIG. 1, the head flange 24 is thinner, and the material cost can be saved.

Also in the exhaust pipe of the second embodiment, similarly to the exhaust pipe of FIG. 1, there is no step on the inner periphery of the exhaust gas flow path, so that the exhaust resistance is small.

Further, since the welding portion does not exist in the flow path of the exhaust gas, residual spatter due to welding does not enter the exhaust gas and enter the combustion chamber of the engine.

Further, since the gasket 26 is strongly sandwiched between the flange-like end 23a of the inner tube 23 and the end face 27a of the cylinder head 27 to make close contact, the end face 27a of the cylinder head 27 is Also, there is no need to make the head flange 24 large. Moreover, the inner pipe 2
3 is thin and has low rigidity, so that the airtightness is improved by the synergistic effect of the overlapping flange-like end 23a and the gasket 26.

In comparison with the conventional exhaust pipe shown in FIG.
The step of the hole flange of the head flange is not required, and the processing of the head flange is easy.

Further, since only the inner pipe 23 contacts the exhaust gas, the exhaust gas is hardly cooled, and the catalyst temperature of the exhaust system can be maintained at a high temperature. Further, since the outer pipe 22 and the inner pipe 23 are separated by the thickness of the cylindrical portion 24b of the head flange 24, heat of the exhaust gas is hardly conducted to the outer pipe 22, and the exhaust gas is hardly cooled. Further, since the head flange 24 is made of a thin steel plate and has a small heat capacity, the exhaust gas is hardly cooled.

Further, since the bent portion 23b of the inner tube 23 and the bent portion 24d of the head flange 24 are in close contact with each other and there is no space between them, a crack is not easily generated in the bent portion 23b of the inner tube 23. If there is a space between the two, the temperature of the air in the space suddenly rises or falls sharply.
The crack is easily generated in b.

The present invention is not limited to the above embodiments, and can be appropriately modified without departing from the scope of the claims.

[0035]

As described above, according to the exhaust pipe of the internal combustion engine of the present invention, the inner pipe is passed through the hole or the cylindrical portion of the flange, and the end of the inner pipe formed in a flange shape is formed. It is supported by overlapping with the flange. Therefore, there is no welding portion for supporting the inner pipe, and the welding portion does not exist in the flow path of the exhaust gas. Therefore, the residual spatter due to welding does not mix into the exhaust gas.

When the inner diameter of the hole of the gasket is adjusted to the inner diameter of the inner pipe, the gasket is strongly sandwiched between the flange-shaped end of the inner pipe and the end face of the cylinder head, so that the gasket has a close contact area. Therefore, it is not necessary to increase the end face and the head flange of the cylinder head, and it is possible to reduce the size of the cylinder head and the head flange.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of an exhaust pipe of an internal combustion engine of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the exhaust pipe of the internal combustion engine of the present invention.

FIG. 3 is a perspective view showing a head flange in the exhaust pipe of FIG. 2;

FIG. 4 is a schematic view showing a structure of an exhaust pipe.

FIG. 5 is a sectional view showing a conventional exhaust pipe.

FIG. 6 is a sectional view showing another conventional exhaust pipe.

[Explanation of symbols]

 11, 21 Exhaust manifold 12, 22 Outer pipe 13, 23 Inner pipe 13a, 23a Flanged end 14, 24 Head flange 15, 26 Gasket 16, 27 Cylinder head 24b Cylindrical part

Claims (2)

[Claims] 1. An exhaust system comprising: a flange fastened to an end face of a cylinder head of an internal combustion engine via a gasket; and an exhaust manifold connected to the flange, wherein exhaust gas exhausted from an exhaust port at an end face of the cylinder head is provided. In an exhaust pipe of an internal combustion engine which leads to the exhaust manifold through a hole of the flange, the exhaust manifold has a double pipe structure including an outer pipe and an inner pipe passing inside the outer pipe, The end of the pipe is connected to the periphery of the hole of the flange, the inner pipe is passed through the hole of the flange, and the end of the inner pipe is formed in a flange shape. An exhaust pipe of an internal combustion engine having an end portion supported by being superimposed on the flange. 2. An exhaust system comprising: a flange fastened to an end face of a cylinder head of an internal combustion engine via a gasket; and an exhaust manifold connected to the flange, wherein exhaust gas exhausted from an exhaust port at an end face of the cylinder head is provided. In an exhaust pipe of an internal combustion engine which leads to the exhaust manifold through a hole of the flange, the exhaust manifold has a double-pipe structure including an outer pipe and an inner pipe passing through the inside of the outer pipe. A cylindrical portion protrudes from the hole, the periphery of the cylindrical portion of the flange is connected to an end of the outer tube, and the inner tube is penetrated through the cylindrical portion of the flange, and the end of the inner tube is formed. An exhaust pipe of an internal combustion engine, which is formed in the shape of a flange, and supports the end of the inner pipe formed in the shape of a flange so as to overlap the flange.