JP2020193597A - Exhaust system - Google Patents

Abstract

To suppress heat release from a portion of a flexible pipe where exhaust gas passes.SOLUTION: An exhaust system 1 for discharging exhaust gas from an engine includes a flexible pipe 26 having a bellows part 26a connecting an end 22a of an upstream side exhaust pipe 22 to an end 24a of a downstream side exhaust pipe 24, and an enclosure pipe 30 surrounding the flexible pipe 26, the enclosure pipe 30 having an outer peripheral wall 32 provided around the flexible pipe 26 along the axial direction, and one end face wall 33 and the other end face wall 34 provided on both axial end sides along the radial direction and linked with the outer peripheral wall 32.SELECTED DRAWING: Figure 2

Description

The present invention relates to an exhaust system that exhausts exhaust gas from an internal combustion engine.

Vehicles such as trucks are equipped with an exhaust system that exhausts the exhaust gas of the engine, which is an internal combustion engine. In some exhaust systems, a plurality of exhaust pipes are connected to form an exhaust path through which exhaust gas flows, and a flexible pipe is used for the connecting portion. The flexible tube has, for example, a bellows portion that absorbs engine vibration.

Jikkenhei 7-355720

By the way, from the viewpoint of properly functioning the bellows portion, the thickness of the flexible pipe is smaller than the thickness of the exhaust pipe. Therefore, heat dissipation is more likely to occur in the flexible pipe portion than in the exhaust pipe portion. When heat is dissipated, the temperature of the exhaust gas passing through the flexible pipe is lowered, which may adversely affect the subsequent processing.

Therefore, the present invention has been made in view of these points, and an object of the present invention is to suppress heat dissipation in a portion of a flexible pipe through which exhaust gas passes.

In one aspect of the present invention, it is an exhaust system for exhausting the exhaust gas of an internal combustion engine, and is a flexible pipe having a bellows portion connecting the end of the first exhaust pipe and the end of the second exhaust pipe. The surrounding tube is provided with an outer peripheral wall provided around the flexible tube along the axial direction, and the surrounding tube is provided along the radial direction on both end sides in the axial direction. Provided is an exhaust system having an end face wall provided and connected to the outer peripheral wall.

Further, the end face wall is a first end face wall on the first exhaust pipe side and a second end face wall on the second exhaust pipe side, and the second end face wall is an end portion of the second exhaust pipe. The first end face wall is not fixed to the end of the first exhaust pipe, and a gap may be formed between the first end face wall and the end of the first exhaust pipe. ..

Further, the exhaust system may further include a heat insulating material provided between the flexible pipe and the surrounding pipe.

Further, the second exhaust pipe may be located on the downstream side of the flexible pipe in the direction in which the exhaust gas flows, and may be further provided with a purification device provided in the second exhaust pipe to purify the exhaust gas. ..

According to the present invention, it is possible to suppress heat dissipation in the portion of the flexible pipe through which the exhaust gas passes.

It is a schematic diagram which shows an example of the structure of the exhaust system 1 which concerns on one Embodiment of this invention. It is a schematic diagram for demonstrating the detailed structure of the surrounding tube 30. It is a schematic view which looked at the other end surface side of the surrounding tube 30 of FIG.

<Exhaust system configuration>
The configuration of the exhaust system according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a schematic view showing an example of the configuration of the exhaust system 1 according to the embodiment. FIG. 2 is a schematic view for explaining a detailed configuration of the surrounding tube 30.
The exhaust system 1 is mounted on a vehicle such as a truck. The exhaust system 1 exhausts the exhaust gas of the engine, which is the internal combustion engine of the vehicle. As shown in FIG. 1, the exhaust system 1 includes an engine 10, an exhaust passage 20, a surrounding pipe 30, and a purification device 40. In FIG. 1, the direction in which the exhaust gas flows is indicated by a broken line arrow.

The engine 10 burns and expands a mixture of fuel and intake air injected into a cylinder (combustion chamber) to generate power. The engine 10 is, for example, a diesel engine, but is not limited to this, and may be, for example, a gasoline engine. In the engine 10, the exhaust gas after combustion is discharged from the cylinder.

The exhaust passage 20 is a passage through which the exhaust gas of the engine 10 flows. The exhaust passage 20 is formed by connecting a plurality of exhaust pipes. In FIG. 1, an upstream side exhaust pipe 22 and a downstream side exhaust pipe 24 are shown as a plurality of exhaust pipes. The upstream exhaust pipe 22 is connected to the exhaust manifold of the engine 10. The downstream exhaust pipe 24 is fixed to, for example, the vehicle body frame of the vehicle. In the present embodiment, the upstream exhaust pipe 22 corresponds to the first exhaust pipe, and the downstream exhaust pipe 24 corresponds to the second exhaust pipe.

As shown in FIG. 2, the upstream exhaust pipe 22 and the downstream exhaust pipe 24 are connected via a flexible pipe 26. The flexible pipe 26 is fixed to the end 22a of the upstream exhaust pipe 22 and the end 24a of the downstream exhaust pipe 24. The flexible pipe 26 has a function of absorbing the vibration of the engine 10. The flexible tube 26 has a stretchable bellows portion 26a (in other words, a tubular bellows). The exhaust gas that has flowed through the upstream exhaust pipe 22 passes through the flexible pipe 26 and flows through the downstream exhaust pipe 24.

As shown in FIG. 2, the surrounding pipe 30 is a pipe that surrounds the flexible pipe 26. Although the details of the surrounding pipe 30 will be described later, a space R is formed between the surrounding pipe 30 and the flexible pipe 26, and the space R has a function of suppressing heat dissipation of the portion of the flexible pipe 26. As a result, it is possible to prevent the temperature of the exhaust gas passing through the flexible pipe 26 from dropping.

As shown in FIG. 1, the purification device 40 is provided in the downstream exhaust pipe 24 located on the downstream side of the surrounding pipe 30 in the direction in which the exhaust gas flows. The purification device 40 is a device that purifies the exhaust gas flowing through the downstream exhaust pipe 24. The purification device 40 has, for example, SCR (Selective Catalytic Reduction). The SCR has a catalyst that reduces NOx in the exhaust gas, and reacts NOx with ammonia to reduce them to harmless nitrogen and water. In general, the purification rate of exhaust gas by SCR increases as the temperature of exhaust gas increases. In the present embodiment, since the temperature drop of the exhaust gas can be suppressed by providing the surrounding pipe 30, it is possible to increase the purification rate of the exhaust gas that has passed through the flexible pipe 26.

<Detailed configuration of the enclosure>
The detailed configuration of the surrounding tube 30 will be described with reference to FIGS. 2 and 3.
FIG. 3 is a schematic view of the other end surface side of the surrounding tube 30 of FIG.

The surrounding pipe 30 is, for example, a cylindrical pipe and covers the flexible pipe 26. As shown in FIG. 2, the surrounding pipe 30 has an outer peripheral wall 32, one end surface wall 33, and the other end surface wall 34. In the present embodiment, the one end face wall 33 corresponds to the first end face wall, and the other end face wall 34 corresponds to the second end face wall.

The outer peripheral wall 32 is a wall located around the flexible pipe 26. The outer peripheral wall 32 is provided around the flexible pipe 26 in a cylindrical shape along the axial direction. The thickness of the outer peripheral wall 32 is larger than the thickness of the flexible pipe 26. In the axial direction, the outer peripheral wall 32 is provided to the outside of the flexible pipe 26.

The one end surface wall 33 is provided along the radial direction on one end side in the axial direction (that is, the upstream side exhaust pipe 22 side). The end face wall 33 is an end face wall forming an end face on one end side of the surrounding pipe 30. The one end surface wall 33 is connected to one end of the outer peripheral wall 32, and there is no gap between the one end surface wall 33 and the outer peripheral wall 32. For example, the one end surface wall 33 is fixed to the outer peripheral wall 32 by welding. The thickness of the one-sided wall 33 is larger than the thickness of the flexible pipe 26, and is, for example, the same as the thickness of the outer peripheral wall 32.

The other end surface wall 34 is provided along the radial direction on the other end side in the axial direction (that is, the downstream side exhaust pipe 24 side). The other end face wall 34 is an end face wall forming the end face on the other end side of the surrounding pipe 30. The other end surface wall 34 is connected to the other end of the outer peripheral wall 32, and there is no gap between the other end surface wall 34 and the outer peripheral wall 32. For example, the other end surface wall 34 is fixed to the outer peripheral wall 32 by welding. The thickness of the other end surface wall 34 is, for example, the same as the thickness of the one end surface wall 33.

By providing the above-mentioned surrounding pipe 30, as shown in FIG. 2, a space R is formed between the surrounding pipe 30 and the flexible pipe 26. The space R is an area surrounded by the flexible pipe 26, the outer peripheral wall 32, the one end surface wall 33, and the other end surface wall 34. The flexible tube 26 can be kept warm because the space R is surrounded by the outer peripheral wall 32, the one end surface wall 33, and the other end surface wall 34 having a large thickness. That is, the space R can suppress heat dissipation in the flexible tube 26. Therefore, it is possible to suppress a decrease in the temperature of the exhaust gas passing through the flexible pipe 26. As a result, the exhaust gas kept at a high temperature flows to the purification device 40 (FIG. 1) provided in the downstream exhaust pipe 24.

In the present embodiment, the other end surface wall 34 is fixed to the end portion 24a of the downstream exhaust pipe 24. Specifically, as shown in FIG. 2, the other end surface wall 34 is fixed to the end portion 24a by the fixing portion 34a on the center side in the radial direction. On the other hand, the one end surface wall 33 is not fixed to the end portion 22a of the upstream exhaust pipe 22. Specifically, as shown in FIG. 2, a gap is formed between the end face wall 33 and the end 22a. As a result, it is possible to prevent the surrounding pipe 30 from interfering with the absorption of vibration of the engine 10 by the flexible pipe 26. Further, since the gap is formed, even if the upstream exhaust pipe 22 is displaced due to the vibration of the engine 10, it is possible to suppress the interference with the one end surface wall 33.

Although not shown in FIG. 2, a heat insulating material may be provided between the flexible pipe 26 and the surrounding pipe 30. For example, the above-mentioned space R is filled with a heat insulating material. As a result, the heat retention function due to the space R can be further enhanced, so that the temperature drop of the exhaust gas can be suppressed more effectively.

In the above, it is assumed that the surrounding tube 30 has a cylindrical shape, but the present invention is not limited to this. For example, the surrounding tube 30 may have a square tubular shape. Also in this case, since the space R is formed between the surrounding pipe 30 and the flexible pipe 26, the temperature drop of the exhaust gas can be suppressed.

<Effect in this embodiment>
The exhaust system 1 described above includes a surrounding pipe 30 that surrounds a flexible pipe 26 that connects the upstream exhaust pipe 22 and the downstream exhaust pipe 24. The surrounding pipe 30 has an outer peripheral wall 32 provided around the flexible pipe 26 along the axial direction, and one end surface wall 33 and the other end surface wall 34 provided along the radial direction.
As a result, the space R surrounded by the flexible pipe 26, the outer peripheral wall 32, the one end surface wall 33, and the other end surface wall 34 has a function of keeping the flexible pipe 26 warm. That is, the space R can suppress heat dissipation in the flexible tube 26. Then, by keeping the flexible pipe 26 warm, it is possible to suppress a decrease in the temperature of the exhaust gas passing through the flexible pipe 26.

In the above, the exhaust system 1 is intended to exhaust the exhaust gas of the engine 10 of the vehicle, but the present invention is not limited to this. For example, the exhaust system 1 may exhaust the exhaust gas of a stationary engine mounted on a power generation device or the like, or may discharge the exhaust gas of an engine mounted on an industrial device such as a construction machine or a ship.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes can be made within the scope of the gist. is there. For example, all or a part of the device can be functionally or physically distributed / integrated in any unit. Also included in the embodiments of the present invention are new embodiments resulting from any combination of the plurality of embodiments. The effect of the new embodiment produced by the combination has the effect of the original embodiment.

1 Exhaust system 10 Engine 22 Upstream exhaust pipe 24 Downstream exhaust pipe 26 Flexible pipe 30 Surrounding pipe 32 Outer wall 33 One end wall 34 One end wall 40 Purification device

Claims (4)

An exhaust system that exhausts the exhaust gas of an internal combustion engine.
A flexible pipe having a bellows portion connecting the end of the first exhaust pipe and the end of the second exhaust pipe,
With a surrounding tube surrounding the flexible tube,
The surrounding tube
An outer peripheral wall provided around the flexible pipe along the axial direction,
It has an end face wall provided along the radial direction on both end sides in the axial direction and connected to the outer peripheral wall.
Exhaust system. The end face wall is a first end face wall on the first exhaust pipe side and a second end face wall on the second exhaust pipe side.
The second end face wall is fixed to the end of the second exhaust pipe.
The first end face wall is not fixed to the end of the first exhaust pipe, and a gap is formed between the first end wall and the end of the first exhaust pipe.
The exhaust system according to claim 1. Further provided with a heat insulating material provided between the flexible pipe and the surrounding pipe.
The exhaust system according to claim 1 or 2. The second exhaust pipe is located downstream of the flexible pipe in the direction in which the exhaust gas flows.
A purification device provided in the second exhaust pipe for purifying the exhaust gas is further provided.
The exhaust system according to any one of claims 1 to 3.

Images