JP2007071118A - Internal combustion engine exhaust pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust pipe of an internal combustion engine capable of suppressing freezing of a switching valve of an exhaust heat recovery device.
An exhaust pipe of an internal combustion engine includes a main exhaust passage 10 through which exhaust flows, a bypass passage that bypasses a part of the main exhaust passage 10, and an exhaust heat recovery device that recovers heat of the exhaust gas that flows through the bypass passage. And a switching valve 12 for switching a passage through which the exhaust flows between the main exhaust passage 10 and the bypass passage. The main exhaust passage 10 is provided with a space AL for storing water on the exhaust downstream side of the switching valve 12.
[Selection] Figure 3

Description

  The present invention relates to an exhaust pipe of an internal combustion engine.

  For example, when the temperature of the internal combustion engine is low, such as during cold start, it is necessary to warm up the engine by raising the cooling water to a predetermined temperature. Therefore, some exhaust passages of an internal combustion engine are provided with an exhaust heat recovery device that heats the cooling water using the heat of the exhaust. Specifically, a catalytic converter, a main exhaust passage, and a silencer are sequentially arranged in the exhaust passage from the exhaust upstream side to the downstream side. This main exhaust passage is provided with a bypass passage that bypasses a part of the main exhaust passage and a switching valve that switches a passage through which the exhaust flows between the main exhaust passage and the bypass passage. An exhaust heat recovery device is provided. This exhaust heat recovery device recovers the heat of the exhaust by exchanging heat between the exhaust flowing through the bypass passage and the cooling water. When the cooling water is heated by the apparatus, the switching valve provided inside the main exhaust passage is closed to shut off the main exhaust passage and to distribute the exhaust to the bypass passage.

  By the way, when heat exchange is performed between the exhaust gas and the cooling water, the water vapor contained in the exhaust gas is cooled and condensed by the cooling water, and the condensed water is returned to the main exhaust passage through the bypass passage. It becomes. If the water returned to the main exhaust passage stays in the portion where the switching valve is disposed, the temperature of the exhaust pipe may decrease after the engine operation ends and the switching valve may freeze.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an exhaust pipe of an internal combustion engine that can suppress freezing of a switching valve of an exhaust heat recovery apparatus.

Hereinafter, means for solving the above-described object and its operation and effects will be described.
The invention according to claim 1 is a main exhaust passage through which exhaust gas from an internal combustion engine circulates, a bypass passage that bypasses a part of the main exhaust passage, and an exhaust heat recovery device that recovers heat of the exhaust gas that flows through the bypass passage And a switching valve that switches a passage through which the exhaust flows between the main exhaust passage and the bypass passage, wherein the main exhaust passage is provided between the switching valve and an outlet portion of the bypass passage. The gist is that a weir is provided to stop the flow of water.

  According to the above configuration, the main exhaust passage is provided with the weir that stops the flow of water between the switching valve and the outlet of the bypass passage, so that the water flowing into the main exhaust passage from the bypass passage to the switching valve Reaching is suppressed. As a result, the switching valve can be prevented from freezing when it is cold.

  Specifically, as in the invention described in claim 2, it is possible to adopt a mode in which a weir is formed by deforming a part of the main exhaust passage to the inside of the main exhaust passage. According to such an aspect, since it is not necessary to form the weir with a separate member, it is possible to suppress freezing of the switching valve while simplifying the configuration of the exhaust pipe of the internal combustion engine.

  According to a third aspect of the present invention, in the exhaust pipe of the internal combustion engine according to the first aspect, the switching valve is provided in the main exhaust passage and the passage through which the exhaust flows is switched to the bypass passage by closing the valve. A sealing member is provided on the inner wall of the main exhaust passage to seal a gap between the inner wall and the switching valve when the switching valve is closed, and the weir is disposed on the exhaust downstream side of the switching valve. The gist is that the seal member is provided.

According to the above configuration, since the weir is formed by the seal member disposed on the exhaust downstream side of the switching valve, the seal member can also function as a weir that stops the flow of water.
According to a fourth aspect of the present invention, there is provided a main exhaust passage through which an exhaust gas from an internal combustion engine circulates, a bypass passage that bypasses a part of the main exhaust passage, and an exhaust heat recovery device that recovers heat of the exhaust gas flowing through the bypass passage And a switching valve that switches a passage through which the exhaust flows between the main exhaust passage and the bypass passage, in which the water is stored on the exhaust downstream side of the switching valve of the main exhaust passage. The gist is that a part is provided.

  According to the above configuration, since the storage part that stores water is provided downstream of the switching valve of the main exhaust passage, the water is switched by storing the water flowing in from the bypass passage in the storage part. Reaching the valve is suppressed. As a result, the switching valve can be prevented from freezing when it is cold.

  Specifically, as in the invention described in claim 5, it is possible to adopt a mode in which a reservoir is formed by deforming a part of the main exhaust passage to the outside of the main exhaust passage. According to such an aspect, since it is not necessary to form a storage part by another member, freezing of the switching valve can be suppressed while simplifying the configuration of the exhaust pipe of the internal combustion engine.

  Further, according to the invention described in claim 6, the main exhaust passage has a double-pipe structure composed of an inner tube and an outer tube, and the storage portion includes an outer peripheral surface of the inner tube and an inner peripheral surface of the outer tube. It is also possible to adopt a mode in which the film is formed by connecting the two.

  Further, according to the invention described in claim 7, the main exhaust passage and the silencer for reducing exhaust noise have a double-pipe structure, and the storage portion has an outer peripheral surface of the main exhaust passage and an inner periphery of the silencer. It is also possible to adopt a mode in which the surface is formed by connecting the surfaces.

  According to an eighth aspect of the present invention, there are provided a main exhaust passage through which an exhaust gas of an internal combustion engine flows, a bypass passage that bypasses a part of the main exhaust passage, and an exhaust heat recovery device that recovers heat of the exhaust gas flowing through the bypass passage. And a switching valve that switches a passage through which exhaust flows between the main exhaust passage and the bypass passage, and an exhaust downstream portion including an outlet portion of the bypass passage in the main exhaust passage The gist is that it is inclined downward.

  According to the above configuration, since the downstream portion of the exhaust including the outlet portion of the bypass passage in the main exhaust passage is inclined downward, the water flowing into the main exhaust passage from the bypass passage is prevented from reaching the switching valve. Is done. As a result, the switching valve can be prevented from freezing when it is cold.

<First Embodiment>
Hereinafter, a first embodiment of an exhaust pipe of an internal combustion engine according to the present invention will be described with reference to FIGS.

As shown in FIG. 1, the exhaust pipe of the internal combustion engine is provided with a catalytic converter 40 for purifying exhaust, a main exhaust passage 10, and a silencer 50 in order from the exhaust upstream side to the exhaust downstream side.
The catalytic converter 40 is a device that purifies exhaust gas by changing carbon monoxide CO, hydrocarbon HC, and nitrogen oxide NOx in the exhaust gas of the internal combustion engine to carbon dioxide CO2, water H2O, and nitrogen N2. In this embodiment, a three-way catalyst made of platinum, rhodium or the like is employed as the catalyst. The silencer 50 reduces noise by reducing the temperature and pressure of the exhaust gas of the internal combustion engine.

  The main exhaust passage 10 is provided with a bypass passage 20 that bypasses a part of the passage 10 and a switching valve 12 that switches a passage through which the exhaust flows between the passage 10 and the bypass passage 20. When the switching valve 12 is closed, the flow of the exhaust gas in the main exhaust passage 10 is blocked, and the exhaust gas flows through the bypass passage 20.

  In the bypass passage 20, an introduction pipe 22 connected to a portion of the main exhaust passage 10 upstream of the position where the switching valve 12 is disposed, and an exhaust heat recovery device 30 connected to the exhaust downstream side of the introduction pipe 22. And a discharge pipe 24 for returning the exhaust gas to the main exhaust passage 10 is provided.

  Connected to the exhaust heat recovery device 30 are a supply passage 32 for supplying cooling water of the internal combustion engine into the device 30 and a discharge passage 34 for discharging the cooling water from the device 30. As schematically shown in the cross-sectional structure of the exhaust heat recovery device 30 in FIG. 2, the exhaust heat recovery device 30 includes narrow tubes 38 </ b> A to 38 </ b> C through which the cooling water supplied from the supply passage 32 circulates. The space 36A, 36B corresponding to the gap is interposed. Exhaust gas introduced into the exhaust heat recovery device 30 from the introduction pipe 22 is discharged from the discharge pipe 24 through the spaces 36A and 36B. And when exhaust_gas | exhaustion passes the clearance gap between thin tube 38A-38C, heat exchange is performed between exhaust_gas | exhaustion and cooling water.

Next, the cross-sectional structures of the main exhaust passage 10 and the silencer 50 will be described in detail with reference to FIG.
As shown in FIG. 3, a part of the main exhaust passage 10 including the end portion on the exhaust downstream side has a double tube structure including an inner tube 14 and an outer tube 16 over the entire circumference. An outlet 24E of the discharge pipe 24 of the bypass passage 20 is connected to the upper part of the outer pipe 16.

  The inner peripheral surface of the end of the outer tube 16 on the exhaust upstream side is welded to the outer peripheral surface of the inner tube 14 over the entire periphery. The inner pipe 14 and the outer pipe 16 are each squeezed toward the inside at a portion on the exhaust downstream side of a portion welded to each other. Specifically, the outer tube 16 is uniformly reduced in diameter over the entire circumference toward the central axis C of the main exhaust passage 10. On the other hand, the inner tube 14 has a lower degree of restriction of the lower part of the tube 14 than an upper degree of restriction. The throttle portions of the inner tube 14 and the outer tube 16 formed in this way are formed in parallel to the central axis C of the main exhaust passage 10 up to the exhaust downstream end. With this configuration, the volume of the space formed between the outer peripheral surface of the inner tube 14 and the inner peripheral surface of the outer tube 16 is the upper portion of the main exhaust passage 10, that is, the central axis of the main exhaust passage 10 in this space. The volume of the lower half space AL from the central axis C is larger than the volume of the upper half space AU from C. Since the lower half space AL functions as a water storage part, the volume ratio of the upper and lower spaces AU, AL is the amount of water condensed in the exhaust heat recovery device 30 and flowing into the main exhaust passage 10. Set accordingly.

  The silencer 50 includes an inner cylinder 52 connected to the outer peripheral surface of the outer pipe 16 of the main exhaust passage 10, an outer cylinder 54 formed outside the inner cylinder 52, and an exhaust upstream side of the inner cylinder 52 and the outer cylinder 54. The wall part 56 which connects the edge part of this is provided. A discharge port 58 is formed in a part of the lower portion of the inner cylinder 52 so that water that has flowed into the silencer 50 from the discharge port 58 has an inner peripheral surface of the outer cylinder 54, an outer peripheral surface of the inner cylinder, and a wall. It will be stored in the space B formed by the inner peripheral surface of the part 56.

4 is a cross-sectional view taken along the line II in FIG.
As shown in FIG. 4, the cross sections of the inner tube 14 and the outer tube 16 are each circular. The central axis Oo of the outer pipe 16 coincides with the central axis C of the main exhaust passage 10, whereas the central axis Oi of the inner pipe 14 is biased upward from the central axis C of the main exhaust passage 10. As described above, the outlet 24E of the discharge pipe 24 of the bypass passage 20 is connected to the upper part of the outer pipe 16, and the water condensed in the exhaust heat recovery device 30 passes through the discharge pipe 24 to the outer periphery of the inner pipe 14. It is stored in the space AL in the lower half of the space formed between the surface and the inner peripheral surface of the outer tube 16.

According to the present embodiment described above, the following operational effects can be obtained.
(1) Since the main exhaust passage 10 is provided with a space AL as a storage portion for storing water downstream of the switching valve 12 from the switching valve 12, the water flowing into the main exhaust passage 10 from the bypass passage 20 is space AL. It is suppressed by this that water reaches | attains to the switching valve 12. As a result, the switching valve 12 can be prevented from freezing when it is cold.

(2) The space formed between the outer peripheral surface of the inner pipe 14 and the inner peripheral surface of the outer pipe 16 is from the central axis C rather than the volume of the space AU above the central axis C of the main exhaust passage 10. The volume of the lower space AL increases. Since this lower space AL functions as a water storage part, the ratio of the volume of the entire space and the volume of the upper and lower spaces AU, AL is condensed in the exhaust heat recovery device 30 and flows into the main exhaust passage 10. It is set according to the amount of water to be used. As a result, it is possible to appropriately set the volume of the space AL as the storage portion without reducing the cross-sectional area of the exhaust gas in the main exhaust passage 10 as much as possible. Further, when water flows out from the space AL to the exhaust downstream side, the water is stored in the space B through the discharge port 58 provided in the silencer 50, so that the water is prevented from returning to the main exhaust passage 10 again. can do.
Second Embodiment
Hereinafter, a second embodiment of an exhaust pipe of an internal combustion engine according to the present invention will be described with reference to FIG. In the present embodiment, the discharge pipe 124 of the bypass passage 120 is connected to the side surface of the silencer 150, and the outlet portion 124E of the discharge pipe 124 opens into the silencer 150, but is different from the first embodiment. . Hereinafter, the difference will be mainly described.

  As shown in FIG. 5, the bypass passage 120 is provided with a discharge pipe 124 for discharging the exhaust gas passing through the exhaust heat recovery device 30 directly into the silencer 150 in parallel with the main exhaust passage 110. The exhaust pipe upstream end of the exhaust pipe 124 is connected to the exhaust heat recovery device 30, and the exhaust downstream end, that is, the outlet 124 E of the exhaust pipe 124 passes through the wall 156 of the silencer 150. Opened inside the silencer 150. Thereby, the water condensed in the exhaust heat recovery device 30 is stored in the silencer 50 through the discharge pipe 124. In the present embodiment, the silencer 150 has a function as a storage unit. In other words, the main exhaust passage 110 and the silencer 150 for reducing exhaust noise form a double pipe structure, and the storage portion connects the outer peripheral surface of the main exhaust passage 110 and the inner peripheral surface of the silencer. Is formed.

According to the present embodiment described above, the following operational effects can be obtained.
(1) Since the main exhaust passage 110 is provided with a silencer 150 as a reservoir that stores water downstream of the switching valve 112, water from the detour passage 120 serves as a silencer 150 as a reservoir. By being stored in the water, it is possible to suppress water from reaching the switching valve 112. As a result, the switching valve 112 can be prevented from freezing when it is cold.
<Third Embodiment>
A third embodiment of the exhaust pipe of the internal combustion engine according to the present invention will be described below with reference to FIG. The present embodiment is different from the first and second embodiments in that the exhaust downstream side portion 210C including the outlet 224E of the bypass passage (not shown) in the main exhaust passage 210 is inclined downward. Hereinafter, the difference will be mainly described.

FIG. 6 shows a cross-sectional structure when the main exhaust passage 210 and the silencer 250 of the exhaust pipe of the internal combustion engine are viewed from the front.
As shown in FIG. 6, in the main exhaust passage 210, a portion 210A on the most upstream side of the exhaust is formed horizontally, and a switching valve 212 is disposed inside the portion 210A. A portion 210B on the exhaust downstream side of the horizontal portion 210A of the main exhaust passage 210 is formed to be inclined upward. On the other hand, in the main exhaust passage 210, a portion 210C on the most downstream side including the outlet portion 224E of the detour passage indicated by a broken-line circle in FIG. 6 is inclined downward, that is, the portion 210C is located downward as the exhaust downstream side. It is formed as follows. In this case, it is desirable to set the inclination angle α to 3 degrees or more. Thereby, it is possible to suppress water from flowing in the exhaust upstream direction in the main exhaust passage 210. Furthermore, if the inclination angle α is set to 6 degrees or more, it is possible to prevent the water from flowing in the upstream direction in the main exhaust passage 210 almost completely.

  A discharge port 258 is formed in a part of the lower portion of the inner cylinder 252 so that water that has flowed into the silencer 250 passes from the discharge port 258 to the inner peripheral surface of the outer cylinder 254, the outer peripheral surface of the inner cylinder, And it will be stored in the space D formed by the inner peripheral surface of the wall portion 256.

According to the present embodiment described above, the following operational effects can be obtained.
(1) In the main exhaust passage 210, the exhaust downstream portion 210C including the outlet portion 224E of the bypass passage is inclined downward, so that water flowing into the main exhaust passage 210 from the bypass passage reaches the switching valve 212. Is suppressed. As a result, the switching valve can be prevented from freezing when it is cold.
<Fourth embodiment>
A fourth embodiment of the exhaust pipe of the internal combustion engine according to the present invention will be described below with reference to FIG. In the present embodiment, seal members 318U and 318L that seal the gap between the inner wall of the main exhaust passage 310 and the switching valve 312 when the switching valve 312 is closed are disposed in the first to third embodiments. Is different. Hereinafter, the difference will be mainly described.

FIG. 7 shows a cross-sectional structure when the main exhaust passage 310 of the exhaust pipe of the internal combustion engine is viewed from the front.
As shown in FIG. 7, the main exhaust passage 310 is provided with a switching valve 312 that switches between the passage 310 and a bypass passage (not shown) for the passage of exhaust gas. When the switching valve 312 is closed, the flow of exhaust gas in the main exhaust passage 310 is blocked, and the exhaust gas flows through the bypass passage. The switching valve 312 is disposed such that the axis of the coaxial 312a is horizontal with respect to the rotation shaft 312a serving as the rotation center. For this reason, the opening degree is adjusted from the closed state (solid line) to the opened state (broken line) by rotating the valve portion 312b in the direction of the arrow about the rotation shaft 312a as the rotation center.

  In a state where the switching valve 312 is closed, the inner wall of the main exhaust passage 310 and the switching valve 312 are connected to the exhaust upstream side portion of the upper end of the valve portion 312b and the exhaust downstream side portion of the lower end of the valve portion 312b. Seal members 318U and 318L for sealing the gap are provided. The seal member 318U is formed in a substantially inverted U shape extending over the upper half circumference of the inner wall of the main exhaust passage 310. On the other hand, the seal member 318L is formed in a substantially U shape extending over the lower half of the inner wall of the main exhaust passage 310. The height h of the seal member 318L is set to a height at which the flow of water that has been condensed by the exhaust heat recovery device 30 and has flowed into the main exhaust passage 10 can be stopped.

According to the present embodiment described above, the following operational effects can be obtained.
(1) Since the main exhaust passage 310 is provided with a seal member 318L as a weir that stops the flow of water between the switching valve 312 and the outlet portion of the bypass passage, the main exhaust passage 310 flows into the main exhaust passage 310 from the bypass passage. It is suppressed that water reaches the switching valve 312. As a result, the switching valve 312 can be prevented from freezing when it is cold.

  (2) Since the weir is formed by the seal member 318L disposed on the exhaust downstream side of the switching valve 312, the seal member 318L can also function as a weir that stops the flow of water.

In addition, the said embodiment can also be changed and implemented as follows.
In the first embodiment, in order to avoid the exhaust gas cross-sectional area in the main exhaust passage 10 from becoming too small, it is formed between the outer peripheral surface of the inner tube 14 and the inner peripheral surface of the outer tube 16. The volume of the lower space AL from the central axis C is larger than the volume of the upper space AU from the central axis C of the main exhaust passage 10. However, when the amount of condensed water generated by the exhaust heat recovery device 30 is not so large, the inner pipe 14 may be formed so that the volumes of the upper half space AU and the lower half space AL are equal. .

  In the first embodiment, a part of the main exhaust passage 10 has a double-pipe structure, but the main exhaust passage need not necessarily have a double-pipe structure as a configuration for providing a storage portion for storing water. . For example, as shown in FIG. 8, the storage portion E may be provided by expanding a part between the switching valve 412 and the outlet portion 424 </ b> E of the bypass passage in the main exhaust passage 410. In short, the main exhaust passage only needs to be provided with a storage portion for storing water on the exhaust downstream side of the switching valve.

  In the second embodiment, the exhaust pipe 124 is disposed in parallel to the main exhaust passage 110, and the outlet portion 124E of the exhaust pipe 124 passes through the silencer wall 156 and opens into the silencer 150. However, the configuration for opening the outlet portion of the discharge pipe inside the silencer is not necessarily limited to such a configuration. For example, as shown in FIG. 9, if the exhaust downstream side portion including the outlet portion 524E of the discharge pipe 524 is disposed so as to open inside the main exhaust passage 510 and the inner cylinder 552 of the silencer 550, the above-mentioned first The same effects as in the second embodiment can be obtained. In this case, the portion on the exhaust downstream side including the outlet portion 524E of the exhaust pipe 524 is included in the main exhaust passage 510, so that the space occupied by the exhaust pipe 524 can be reduced. Further, if the discharge port 558 is formed in a part of the lower portion of the inner cylinder 552, the water flowing into the inner cylinder 552 from the discharge pipe 524 is the outer peripheral surface of the inner cylinder 552 of the silencer 550 and the inner peripheral surface of the outer cylinder 554. , And the space formed by the inner peripheral surface of the wall portion 556. As a result, it is possible to prevent water stored in the same space from flowing into the main exhaust passage 210 again.

  In the third embodiment, only the most downstream portion 210 </ b> C including the outlet 224 </ b> E of the bypass passage in the main exhaust passage 210 is formed to be inclined downward. However, the entire portion of the main exhaust passage 210 on the exhaust downstream side of the position where the switching valve 212 is disposed may be inclined downward. In short, it suffices if the downstream portion of the main exhaust passage including the outlet portion of the bypass passage is inclined downward.

  In the fourth embodiment, the seal member 318L disposed on the exhaust downstream side of the switching valve 312 also functions as a weir that suppresses the backflow of water. However, such a weir structure may be formed by deforming the main exhaust passage 610 inside the passage 610 between the switching valve 612 and the outlet portion 624E of the bypass passage, for example, as shown in FIG. . Further, a weir may be provided on the inner wall of the main exhaust passage 610 by a member different from the main exhaust passage 610. In short, what is necessary is just to provide the weir which stops the flow of water between the switching valve 612 and the exit part of a bypass path in the main exhaust passage.

  The main exhaust passage is provided with a reservoir for storing water downstream of the switching valve, and the downstream portion of the main exhaust passage including the outlet of the bypass passage is inclined downward. Two or three configurations may be combined such that the main exhaust passage is provided with a weir that stops the flow of water between the switching valve and the outlet of the bypass passage.

1 is a front view showing a schematic configuration of an exhaust pipe of an internal combustion engine according to a first embodiment of the present invention. Sectional drawing of the exhaust heat recovery apparatus concerning the embodiment. Sectional drawing of the main exhaust passage and silencer concerning the embodiment. Sectional drawing along the II line | wire in FIG. Sectional drawing of the exhaust pipe of the internal combustion engine concerning 2nd Embodiment of this invention. Sectional drawing of the exhaust pipe of the internal combustion engine concerning 3rd Embodiment of this invention. Sectional drawing of the exhaust pipe of the internal combustion engine concerning 4th Embodiment of this invention Sectional drawing which shows the example of a change of the exhaust pipe of the internal combustion engine of this invention. Sectional drawing which shows the other modification of the exhaust pipe of the internal combustion engine of this invention. Sectional drawing which shows the other modification of the exhaust pipe of the internal combustion engine of this invention.

Explanation of symbols

  10, 110, 210, 310, 410, 510, 610 ... main exhaust passage, 12, 112, 212, 312, 412, 512, 612 ... switching valve, 312a ... rotating shaft, 312b ... valve part, 14 ... inner pipe, 16 ... outer pipe, 318 ... seal member, 20, 120, 520 ... detour passage, 22, 122, 522, 622 ... introduction pipe, 24, 124, 424, 524, 624 ... discharge pipe, 24E, 124E, 224E, 424E , 524E, 624E ... outlet, 30 ... exhaust heat recovery device, 32 ... supply passage, 34 ... discharge passage, 40 ... catalytic converter, 50, 150, 250, 550 ... silencer, 52, 152, 252, 552 ... inside Tube, 54, 154, 254, 554 ... Outer tube, 56, 156, 256, 556 ... Wall, 58, 258, 558 ... Discharge port.

Claims (8)

A main exhaust passage through which the exhaust gas of the internal combustion engine circulates, a bypass passage that bypasses a part of the main exhaust passage, an exhaust heat recovery device that recovers heat of the exhaust gas that flows through the bypass passage, and the bypass that is the same as the main exhaust passage In an exhaust pipe of an internal combustion engine comprising a switching valve that switches a passage through which exhaust flows through the passage,
An exhaust pipe for an internal combustion engine, wherein the main exhaust passage is provided with a weir that stops water flow between the switching valve and an outlet of the bypass passage.   The exhaust pipe of an internal combustion engine according to claim 1, wherein the weir is formed by deforming a part of the main exhaust passage to the inside of the main exhaust passage.   The switching valve is provided in the main exhaust passage and switches a passage through which exhaust flows by closing the valve to the bypass passage. When the switching valve is closed to the inner wall of the main exhaust passage, The exhaust pipe for an internal combustion engine according to claim 1, wherein a seal member for sealing a gap with the switching valve is provided, and the weir is formed by the seal member provided on the exhaust downstream side of the switching valve. A main exhaust passage through which the exhaust gas of the internal combustion engine circulates, a bypass passage that bypasses a part of the main exhaust passage, an exhaust heat recovery device that recovers heat of the exhaust gas that flows through the bypass passage, and the bypass that is the same as the main exhaust passage In an exhaust pipe of an internal combustion engine comprising a switching valve that switches a passage through which exhaust flows through the passage,
An exhaust pipe for an internal combustion engine, characterized in that a storage section for storing water is provided downstream of the switching valve in the main exhaust passage.   The exhaust pipe of the internal combustion engine according to claim 4, wherein the storage portion is formed by deforming a part of the main exhaust passage to the outside of the main exhaust passage.   The main exhaust passage has a double tube structure including an inner tube and an outer tube, and the storage portion is formed by connecting an outer peripheral surface of the inner tube and an inner peripheral surface of the outer tube. 5. An exhaust pipe for an internal combustion engine according to 4.   The main exhaust passage and the silencer for reducing exhaust noise have a double pipe structure, and the storage portion is formed by connecting the outer peripheral surface of the main exhaust passage and the inner peripheral surface of the silencer. An exhaust pipe for an internal combustion engine according to claim 4. A main exhaust passage through which the exhaust gas of the internal combustion engine circulates, a bypass passage that bypasses a part of the main exhaust passage, an exhaust heat recovery device that recovers heat of the exhaust gas that flows through the bypass passage, and the bypass that is the same as the main exhaust passage In an exhaust pipe of an internal combustion engine comprising a switching valve that switches a passage through which exhaust flows through the passage,
An exhaust pipe for an internal combustion engine, wherein a portion of the main exhaust passage on the exhaust downstream side including an outlet portion of the bypass passage is inclined downward.

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