JPH08338238A - Double pipe type exhaust manifold - Google Patents

Abstract

PURPOSE: To prevent generation of a crack in a branch inner pipe even if thermal stress due to exhaust gas is applied to the branch inner pipe in a double pipe type exhaust manifold installed to a cylinder head in an engine. CONSTITUTION: A double pipe type exhaust manifold is constructed of a flange 11 provided with an opening hole 13 communicated to an exhaust port 12A in a cylinder head 12, a branch outer pipe 9 whose one end 9A is inserted and fitted to the opening hole 13 in the flange 11, a collar 10 in which one end 10A is fitted and fixed in the one end 9A in the branch outer pipe 9 while the other end 10B is positioned in the vicinity of the flange 11, and a branch inner pipe 8 which is inserted into the other end 10B in the collar 10 and provided with a clearance 15 between the branch outer pipe 9 and itself.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double pipe type exhaust manifold mounted on a cylinder head of an engine.

[0002]

2. Description of the Related Art In general, it is required to prevent the temperature of exhaust gas from decreasing and to enhance the catalytic activity of a metal catalytic converter at engine start. In accordance with such a demand, a double-pipe type exhaust manifold which reduces the heat capacity of the inner pipe to reduce the amount of heat taken from the exhaust gas is disclosed, for example, in Japanese Utility Model Publication No. 2-1129.
It is disclosed as shown in Japanese Patent No. 26.

As a double-pipe type exhaust manifold of this type, for example, one shown in FIG. 8 is known. In the figure, reference numeral 101 is a double pipe type exhaust manifold, and this double pipe type exhaust manifold 101 is provided with a main double pipe 102 and branch double pipes 103, 103, 103.

The main double pipe 102 is composed of a main inner pipe 104 and a main outer pipe 105, and a gap 106 is formed between the main inner pipe 104 and the main outer pipe 105. The main double pipe 102 is a main inner pipe 104 and a main outer pipe 105.
Has a gas discharge flange 107 fixed to the base end thereof. The branch double pipe 103 includes an inner branch pipe 108 and an outer branch pipe 109. The tip of the branch inner tube 108 is fixed to the tip of the branch outer tube 109. The branch inner pipe 108 is connected to the main inner pipe 104, and the branch outer pipe 109 is connected to the main outer pipe 105.

Branch inner pipe 108 and branch outer pipe 109
A gap 110 is formed between them. Branch double tube 1
03 has a flange 111 for gas intake, and the flange 1
11, the exhaust port 112A of the cylinder head 112
Is formed with a gas intake 113.

[0006]

However, in the conventional double pipe type exhaust manifold, the branch double pipe 10 is used.
The branch inner pipe 108 receives thermal stress due to the difference in thermal expansion between the branch outer pipe 109 and the branch inner pipe 108 of No. 3, but since the tip of the branch inner pipe 108 is fixed to the tip of the branch outer pipe 109, The tip of the branch outer tube 109 is constrained by the tip of the branch outer tube 109, the inner branch tube 108 is prevented from freely expanding and contracting, and the inner branch tube 108 may be cracked.

In particular, since the vicinity of the flange 111 at the tip of the branch outer tube 109 is cooled by the cylinder head 112 cooled by a water jacket (not shown), the temperature of the branch outer tube 109 and the branch inner tube 108 is reduced. Since the difference is large, the risk of cracks occurring near the flange 111 of the branch inner pipe 108 is increased. Therefore,
For example, as shown in FIG. 9, in the double-tube exhaust manifold 200, one end 203A of the branch outer tube 203 is fitted into the opening hole 202 of the flange 201 and fixed by arc welding, and the tip 203A of the branch outer tube 203 is fixed. SUS mesh material 2 between the tip 204A of the branch inner pipe 204
It is conceivable to attach 05 to allow the tip end 204A of the branch inner pipe 204 to slide. In this case, the exhaust gas flowing through the branch inner pipe 204 enters the gap 206 via the SUS mesh material 205, the heat amount of the exhaust gas is taken by the branch outer pipe 203, and the temperature of the exhaust gas in the branch inner pipe 204 is maintained. The original function of the tubular exhaust manifold 200 will be impaired.

The present invention has been made to solve the above problems, and an object thereof is to prevent cracks from occurring in the branch inner pipe even when the branch inner pipe is subjected to thermal stress due to exhaust gas. A heavy-duty exhaust manifold is provided.

[0009]

According to the first aspect of the present invention,
A flange having an opening hole communicating with the exhaust port of the cylinder head, a branch outer tube having one end fitted and fixed in the opening hole of the flange, and one end fitted and fixed in one end of the branch outer tube, the other end Is composed of a collar located in the vicinity of the flange and an inner branch tube which is inserted into the other end of the collar to form a gap between the outer branch tube and the collar.

According to a second aspect of the present invention, there is provided a flange having an opening hole communicating with the exhaust port of the cylinder head, and a curl portion formed at one end by being bent inward, and the curl portion is fitted into the opening hole of the flange. It is characterized in that it is provided with an outer branch tube that is inserted and fixed, and an inner branch tube that has one end inserted into the groove of the curl portion and has a gap formed between it and the outer branch tube.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the double-pipe type exhaust manifold described above, a main double pipe is formed with a gap between a main outer pipe connected to the branch outer pipe and a main inner pipe connected to the branch inner pipe. In addition, a plurality of positioning portions for the main inner pipe are provided on the side close to the flange and on the side far from the flange cut along the axis of the main double pipe in parallel with the flange. It is characterized in that they are separated by a predetermined distance in the longitudinal direction.

[0012]

According to the first aspect of the invention, since the vicinity of the flange of the branch outer pipe is cooled by the cylinder head cooled by the water jacket, the temperature difference between the branch outer pipe and the branch inner pipe is large, and the branch outer pipe has a large temperature difference. Although the thermal stress acting on the inner pipe is large, the other end of the collar is located near the flange, so the branch inner pipe is expandably connected to the other end of the collar near the flange, The thermal stress acting on the tube is absorbed by the expansion and contraction.

Further, the exhaust gas inside the branch inner pipe does not escape to the gap between the branch inner pipe and the branch outer pipe, the inside of the branch inner pipe is kept at a high temperature, and the original gas of the double pipe type exhaust manifold is maintained. The function is demonstrated.

According to the second aspect of the invention, the branch inner pipe is subjected to thermal stress due to the temperature change of the exhaust gas, but since it is inserted in the groove of the curl portion of the collar fixed to the branch outer pipe, Stretch freely with respect to. Further, the same effect as that of the invention according to claim 1 occurs. In the invention according to claim 3, since the main inner pipe is constrained by the plurality of positioning portions of the main double pipe even if there is pulsation due to exhaust gas of the double pipe type exhaust manifold and vibration due to traveling of the vehicle. The main inner tube is prevented from vibrating inside the main outer tube.

Further, since the plurality of positioning portions are separated from each other by a predetermined distance in the longitudinal direction, the main inner pipe is not subjected to the restraining force in the radial direction. In addition, at the time of assembling and manufacturing the double pipe type exhaust manifold, the main inner pipe is radially positioned with respect to the main outer pipe by the plurality of positioning portions.

[0016]

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

A double pipe type exhaust manifold according to embodiments of the present invention will be described with reference to FIGS. 1 to 4. In FIG. 1, reference numeral 1 is a double pipe type exhaust manifold, and this double pipe type exhaust manifold 1 is provided with a main double pipe 2 and branch double pipes 3, 3, 3. The main double pipe 2 is a main inner pipe 4 (plate thickness: 0.5 to 0.8 m
m) and the main outer pipe 5 (plate thickness: 1.5 to 2.0 mm), and a gap 6 is formed between the main inner pipe 4 and the main outer pipe 5. The main inner tube 4 is made of stainless steel containing 18% chromium, and the main outer tube 5 is made of stainless steel containing 13% chromium.

The main double pipe 2 has a gas discharge flange 7, and the base ends 4A, 5A of the main inner pipe 4 and the main outer pipe 5 are fixed to the gas discharge flange 7, and the main inner pipe 4 The base ends 4A and 5A of the main outer tube 5 are connected in the longitudinal direction. The branch double pipe 3 includes a branch inner pipe 8 (plate thickness: 0.5 to 0.8 mm) and a branch outer pipe 9 (plate thickness:
1.5 to 2.0 mm) and a collar 10, the branch inner pipe 8 is connected to the main inner pipe 4, and the branch outer pipe 9 is connected to the main outer pipe 5. The branch inner pipe 8 and the collar 10 are made of stainless steel containing 18% chromium, and the branch outer pipe 9 is made of stainless steel containing 13% chromium.

The branch double pipe 3 has a flange 11 for taking in gas, and the flange 11 is formed with an opening hole 13 communicating with the exhaust port 12A of the cylinder head 12. Then, as shown in FIG. 2, one end 9 </ b> A of the branch outer tube 9 is fitted into the opening hole 13 of the flange 11.
One end 10A of the collar 10 is fitted into the inner peripheral surface 9B of the one end 9A of the branch outer tube 9. One end 9 of the branch outer tube 9
A and one end 10A of the collar 10 are fixed to the opening hole 13 of the flange 11 by arc welding to form a bead 14.

At the other end 10B of the collar 10, a branch inner pipe 8 is provided.
Are fitted to the outside and a gap 15 is formed between the branch outer pipe 9 and the branch inner pipe 8. Then, FIG. 3 and FIG.
As shown in FIG. 2, the main double pipe 2 is provided on a side L1 near the flange 11 and a side L2 far from the flange 11 of a horizontal plane L on the drawing cut along the axis A of the main double pipe 2 in parallel with the flange 11. A pair of positioning portions 16 and 17 for the main inner pipe 4 are provided respectively.

The first positioning portion 16 is a concave portion formed on the outer branch tube 9 and formed with an arc-shaped bead extending in the radial direction, and is inclined to the right with respect to a vertical plane H in the drawing by about 45 degrees. It is located and is in contact with the main inner pipe 4. The second positioning portion 17 is a concave portion formed on the outer branch tube 9 and formed with an arc-shaped bead extending in the radial direction, and is positioned at a tilt of about 45 degrees downward with respect to the horizontal plane L in the drawing. , Axis A
The point is symmetrical with respect to the first positioning portion 16, and is in contact with the main inner pipe 4.

The first positioning portion 16 and the second positioning portion 17 are separated by a predetermined distance in the longitudinal direction. next,
The operation and effect of this embodiment will be described. In the branch double pipe 3, the branch inner pipe 8 receives thermal stress due to the difference in thermal expansion between the branch outer pipe 9 and the branch inner pipe 8 and the temperature change of the exhaust gas, but the collar 10 fixed to the branch outer pipe 9 is subjected to thermal stress.
Since it is inserted into the other end 10B of the branch inner tube 8, it is possible to prevent the branch inner tube 8 from freely expanding and contracting with respect to the collar 10 and causing cracks. Here, by the first positioning portion 16 and the second positioning portion 17 in the main double pipe 2, the main outer pipe 5
Since the main inner pipe 4 is positioned in the radial direction, the branch inner pipe 8 expands and contracts in the longitudinal direction of the main branch pipe 8 as a base.

In particular, the vicinity of the flange 11 of the branch outer tube 9 is cooled by the cylinder head 12 cooled by a water jacket (not shown),
The temperature difference between the branch outer tube 9 and the branch inner tube 8 is large,
Although the thermal stress acting on the branch inner pipe 8 is large, since the other end 10B of the collar 10 is located near the flange 11, the branch inner pipe 8 is located near the flange 11.
Is elastically connected to the other end 10B of the collar 10, and the thermal stress acting on the branch inner pipe 8 is absorbed by the expansion and contraction. Therefore, it is possible to prevent the possibility of cracks in the vicinity of the flange 11 of the branch inner pipe 8.

The exhaust gas inside the branch inner pipe 8 is
The inside of the branch inner pipe 8 is kept at a high temperature without escaping into the gap 15 between the branch inner pipe 8 and the branch outer pipe 9,
The original function of the double pipe type exhaust manifold 1 can be exhibited. On the other hand, in the main double pipe 2, even if there is pulsation due to the exhaust gas of the double pipe type exhaust manifold 1 and vibration due to the traveling of the vehicle, the main inner pipe 4 is prevented by the first positioning portion 16 and the second positioning portion 17. Being restrained,
It is possible to prevent the main inner tube 4 from vibrating in the radial direction within the main outer tube 5.

That is, the main inner pipe 4 tries to vibrate in the longitudinal direction of the branch inner pipe 8 (vertical direction in the drawings of FIGS. 2 and 3) together with the branch inner pipe 8 which can be displaced in the longitudinal direction. However, the upward displacement of the main inner pipe 4 in the drawing is restricted by the first positioning portion 16, and the downward displacement of the main inner pipe 4 in the drawing is restricted by the second positioning portion 17. Further, since the first positioning portion 16 and the second positioning portion 17 are separated from each other by a predetermined distance in the longitudinal direction, the main inner pipe 4 does not receive a restraining force in the radial direction and the main inner pipe 4 moves in the radial direction. It can be easily expanded and contracted.

In addition, the double pipe type exhaust manifold 1
When assembling and manufacturing the first positioning part 16 and the second positioning part 1
By 7, the main inner pipe 4 is radially positioned with respect to the main outer pipe 5. Therefore, the main inner pipe 4 can be easily assembled to the main outer pipe 5 at a proper position on the drawing. In this embodiment, the first positioning portion 1
6, a concave portion formed of an arc-shaped bead is given as an example of the second positioning portion 17, but a concave portion formed of an emboss may be used. Further, the first positioning portion 16 is positioned at an angle of about 45 degrees to the right with respect to the vertical surface H in the drawing, and the second positioning portion 17 is positioned below the horizontal surface L in the drawing by approximately 45 degrees.
Although it is located at an angle, it is not limited to such an angle. It suffices for the first positioning portion 16 to be on the side L1 closer to the flange 11 with respect to the horizontal surface L of the main double pipe 2, and the second positioning portion 17 is a flange for the horizontal surface L of the main double pipe 2. It may be on the side L2 far from 11.

Further, in the present embodiment, the main double pipe 2 is formed with the first positioning portion 16 which is a concave portion which comes into contact with the main inner pipe 4, but as shown in FIG. Instead of the first positioning portion 16, the first positioning portion 18 that is a convex portion that abuts the main outer pipe 5 may be formed on the main inner pipe 4 in a corresponding manner. The first positioning portion 18 is positioned at an angle of about 45 degrees to the right with respect to the vertical plane H in the drawing.

Further, in the present embodiment, the main double pipe 2 is formed with the second positioning portion 17 which is a concave portion which comes into contact with the main inner pipe 4, but as shown in FIG. Instead of the second positioning portion 17, the main outer tube 5
It is also possible to form the second positioning portion 19 composed of a convex portion that abuts against the. The second positioning portion 19 is located at an angle of approximately 45 degrees downward with respect to the horizontal plane L in the drawing, and is in a position symmetrical with respect to the first positioning portion 18 with respect to the axis A.

In this embodiment, the color 10
The inner branch pipe 8 is located outside the other end 10B of the collar 10 and is inserted into the other end 10B of the collar 10.
It is also possible to insert and insert it inside. In addition, in this embodiment, the base ends 4A and 5A of the main inner pipe 4 and the main outer pipe 5 are fixed to the gas discharge flange 7, and the base ends 4A and 5A of the main inner pipe 4 and the main outer pipe 5 are fixed. Are integrated, but the base ends 4A and 5A of the main inner pipe 4 and the main outer pipe 5
Can be connected so that the base end 4A of the main inner pipe 4 slides with respect to the base end 5A of the main outer pipe 5 along the longitudinal direction.

Further, although the number of positioning portions is two in the present embodiment, it may be three or more. Further, in this embodiment, the main inner pipe 4 is made of stainless steel containing 18% chromium, and the main outer pipe 5 is made of stainless steel containing 13% chromium. Tube 8, color 10
The stainless steel containing 18% chromium is used as the material of and the stainless steel containing 13% chromium is used as the material of the branch outer pipe 9. The main inner pipe 4, the main outer pipe 5, and the branch inner pipe 8, stainless steel can also be used for the branch outer tube 9 and the collar 10 with the chromium content in the range of 13% to 20%.

Next, a double pipe type exhaust manifold according to the embodiments of the present invention will be described. The double pipe type exhaust manifold according to the present embodiment has the same overall structure as the double pipe type exhaust manifold according to the embodiments of the present invention described in claims 1 and 3, and only different portions will be described. In the present embodiment, claim 1,
The same components as those of the double pipe type exhaust manifold according to the embodiment of the invention described in 3 are given the same reference numerals and the description thereof will be omitted.

FIG. 7 shows a sectional view corresponding to the sectional view taken along the line I--I of FIG. In the figure, reference numeral 21 is a branch outer tube, and the branch outer tube 21 has one end 21A thereof.
It has a curl portion 22. The curl portion 22 is bent inward and is arc-welded to form the opening hole 13 of the flange 11.
It is fixed by being inserted into. One end 24A of the branch inner pipe 24 is inserted into the groove 23 of the curl portion 22, and a gap 25 is formed between the branch inner pipe 24 and the branch outer pipe 21. Here, stainless steel containing 18% chromium is used as the material of the branch inner pipe 24, and the branch outer pipe 21
13% chromium-containing stainless steel is used as the material.

According to this embodiment, the same actions and effects as the double-tube type exhaust manifold according to the embodiments of the invention described in claims 1 and 3 are produced. In this embodiment, the inner branch tube 24 is made of stainless steel containing 18% chromium, and the outer branch tube 21 is made of stainless steel containing 13% chromium. The inner tube 24 and the branch outer tube 21 have a chromium content of 13
It is also possible to use stainless steel in the range of 20% to 20%.

[0034]

According to the first aspect of the present invention, the branch inner pipe is thermally stressed by the thermal expansion difference between the branch outer pipe and the branch inner pipe and the temperature change of the exhaust gas, but is fixed to the branch outer pipe. Since it is inserted into the other end of the collar, it can freely expand and contract in the longitudinal direction with respect to the collar, and it is possible to prevent cracks from occurring in the branch inner pipe.

In particular, since the other end of the collar is located near the flange, the thermal stress acting on the branch inner pipe is absorbed by the expansion and contraction of the branch inner pipe, and there is a risk that cracks may occur near the flange of the branch inner pipe. It can be prevented. In addition, the exhaust gas inside the branch inner pipe does not escape to the gap between the branch inner pipe and the branch outer pipe, but keeps the inner temperature of the branch inner pipe at a high temperature, and exhibits the original function of the double-pipe exhaust manifold. it can.

According to the invention of claim 2, the same effect as that of the invention of claim 1 can be obtained. According to the third aspect of the present invention, the main inner pipe is radially positioned with respect to the main outer pipe by the plurality of positioning portions. Therefore, the pulsation due to the exhaust gas of the double pipe type exhaust manifold and the traveling of the vehicle Even if there is vibration due to, it is possible to prevent the main inner pipe from vibrating within the main outer pipe by restraining the main inner pipe by the plurality of positioning portions.

Further, since the plurality of positioning portions are separated by a predetermined distance in the longitudinal direction, the main inner pipe can be easily expanded and contracted in the radial direction without receiving the restraining force in the radial direction. Further, during assembly and production of the double-pipe type exhaust manifold, the main inner pipe can be positioned in the radial direction with respect to the main outer pipe by the plurality of positioning portions, and the main inner pipe can be easily and easily arranged on the drawing. Can be installed in the regular position.

[Brief description of drawings]

FIG. 1 is an external view of a double pipe type exhaust manifold according to an embodiment of the invention described in claims 1 and 3.

FIG. 2 is a sectional view taken along line I-I of FIG.

FIG. 3 is a sectional view taken along line II-II in FIG.

FIG. 4 is a sectional view taken along line III-III in FIG.

5 is a cross-sectional view corresponding to a cross-sectional view taken along line II-II in FIG. 1 and showing a first positioning portion.

FIG. 6 is a cross-sectional view corresponding to a cross-sectional view taken along line III-III in FIG. 1 and showing a second positioning portion.

FIG. 7 is a cross-sectional view corresponding to a cross-sectional view taken along line I-I of FIG. 1 according to the embodiment of the invention described in claims 2 and 3;

FIG. 8 is an external view of a conventional double pipe type exhaust manifold.

FIG. 9 is an external view of a conventional double pipe type exhaust manifold.

[Explanation of symbols]

 1 Double-pipe type exhaust manifold 2 Main double pipe 4 Main inner pipe 5 Main outer pipe 6 Gap 8 Branch inner pipe 9 Branch outer pipe 9A One end 10 Color 10A One end 10B Other end 11 Flange 12 Cylinder head 12A Exhaust port 13 Opening hole 15 Gap 16 First Positioning Part 17 Second Positioning Part 21 Branch Outer Tube 21A One End 22 Curl Part 23 Groove Gap 24 Branch Inner Tube 24A One End 25 Gap A Axis L Surface L1 Side Near Flange L2 Far Side

Claims (3)

[Claims] 1. A flange (11) having an opening hole (13) communicating with an exhaust port (12A) of a cylinder head (12), and one end (9A) fitted into the opening hole (13) of the flange (11). Branch outer tube (9) fixed and fixed, and one end (10A) inside one end (9A) of the branch outer tube (9)
Is inserted and fixed, and the other end (10B) has a flange (1
1) In the branch formed by forming a gap (15) between the collar (10) located in the vicinity of 1) and the outer branch tube (9) inserted into the other end (10B) of the collar (10). A double-pipe type exhaust manifold comprising a pipe (8). 2. A flange (11) having an opening hole (13) communicating with an exhaust port (12A) of a cylinder head (12), and a curl portion (22) formed by bending inward at one end (21A). Having a curl portion (22) with a flange (11)
Between the branch outer pipe (21) fitted and fixed in the opening hole (13) of the branch, and one end (24A) inserted into the groove (23) of the curl portion (22) so as to be connected to the branch outer pipe (21). And a branch inner pipe (24) having a gap (25) formed therein. 3. A main outer pipe (5) connected to the branch outer pipe (9) and a main inner pipe (4) connected to the branch inner pipe (8) via a gap (6) between the main outer pipe (5) and the main inner pipe (4). Heavy pipe (2)
Is formed on the main double pipe (2) so as to pass through the axis (A) of the main double pipe (2) in parallel with the flange (11), and the side close to the flange (11) of the surface (L). A plurality of positioning parts (1) for the main inner pipe (4) are provided on the side (L2) remote from (L1).
6, 17) are provided, and the plurality of positioning portions (16, 17) are provided in the main double pipe (2).
The double-pipe exhaust manifold according to claim 1 or 2, wherein a predetermined distance is provided in the longitudinal direction of the.