JP2021131030A - Exhaust structure - Google Patents

Abstract

To provide an exhaust structure that can improve performance for cooling an exhaust gas more than before.SOLUTION: An exhaust structure includes: an exhaust pipe through which an exhaust gas emitted from an internal combustion engine flows; an inner pipe provided downstream of the exhaust pipe; and an outer pipe provided so as to cover the inner pipe and including an outside air introduction part for introducing outside air. An opening part for causing the outside air introduced from the outside air introduction part to flow into the inner pipe is provided at an outer peripheral surface of the inner pipe. The opening part has a shape capable of causing a swirl flow inside the inner pipe.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to an exhaust structure.

Conventionally, an exhaust gas equipped with an exhaust pipe through which exhaust gas discharged from an internal combustion engine flows and an exhaust diffuser (also referred to as an exhaust cooler) provided on the downstream side of the exhaust pipe to mix the exhaust gas with outside air and discharge the exhaust gas into the atmosphere. The structure is known (see, for example, Patent Document 1).

JP-A-2009-91910

However, the conventional exhaust structure has room for improvement in terms of exhaust gas cooling performance.

An object of one aspect of the present disclosure is to provide an exhaust structure capable of further improving the cooling performance of the exhaust gas.

In order to achieve the above object, the exhaust structure according to one aspect of the present disclosure includes an exhaust pipe through which exhaust gas discharged from an internal combustion engine flows, an inner pipe provided on the downstream side of the exhaust pipe, and the inner pipe. It has an outer pipe provided so as to cover and provided with an outside air introduction portion for introducing outside air, and an opening on the outer peripheral surface of the inner pipe for allowing the outside air introduced from the outside air introduction portion to flow into the inner pipe. A portion is provided, and the opening has a shape that causes a swirling flow in the inner pipe.

According to the present disclosure, the cooling performance of the exhaust gas can be further improved.

Schematic diagram showing the exhaust structure according to the embodiment of the present disclosure. The figure which shows the appearance of the inner pipe which concerns on embodiment of this disclosure. AA cross-sectional view of FIG.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

The exhaust structure 100 of the present embodiment will be described with reference to FIG. FIG. 1 is a schematic view showing an exhaust structure 100 of the present embodiment. The alternate long and short dash line A shown in FIG. 1 indicates the axial center of each of the exhaust pipe 1, the inner pipe 2, and the outer pipe 4 (hereinafter, referred to as “axial center A”). The axial direction is the left-right direction in FIG.

The exhaust structure 100 shown in FIG. 1 is mounted on, for example, a vehicle equipped with an internal combustion engine (for example, a commercial vehicle such as a bus or a truck). The internal combustion engine may be a diesel engine or a gasoline engine.

The exhaust pipe 1 is a tubular pipe through which the exhaust gas discharged from the internal combustion engine flows. The arrow a shown in FIG. 1 indicates the flow direction of the exhaust gas in the exhaust pipe 1.

Although not shown, the upstream end of the exhaust pipe 1 is connected to an exhaust manifold provided in the internal combustion engine. Further, the downstream end of the exhaust pipe 1 is connected to the inner pipe 2.

The inner pipe 2 is a tubular member provided on the downstream side of the exhaust pipe 1. The upstream end of the inner pipe 2 is connected to the exhaust pipe 1. Examples of the inner pipe 2 include a tail pipe that can be attached to and detached from the exhaust pipe 1.

The inner diameter of the inner pipe 2 is uniform in the axial direction of the inner pipe 2 (in other words, from the upstream end to the downstream end of the inner pipe 2).

FIG. 2 is a schematic view showing the appearance of the inner pipe 2. FIG. 3 is a cross-sectional view taken along the line AA of FIG. As shown in FIGS. 2 and 3, a plurality of openings (through holes) 3 are provided on the outer peripheral surface of the inner pipe 2. The opening 3 is inclined with respect to the axial direction of the inner pipe 2. In FIG. 1, the illustration of each opening 3 is omitted.

The outer pipe 4 is a tubular member provided so as to cover the inner pipe 2 on the downstream side of the exhaust pipe 1. However, the inner peripheral surface of the outer pipe 4 and the outer peripheral surface of the inner pipe 2 are not in contact with each other. That is, a space serving as a flow path for the outside air introduced from the outside air introduction portion 5 is provided between the inner peripheral surface of the outer pipe 4 and the outer peripheral surface of the inner pipe 2.

The outer pipe 4 is fixed to the exhaust pipe 1 or the inner pipe 2 by a member (not shown). Examples of the outer pipe 4 include an exhaust diffuser that can be attached to and detached from the exhaust pipe 1 or the inner pipe 2.

The downstream end opening 4a of the outer pipe 4 faces the atmosphere.

The outer pipe 4 has an outside air introduction unit 5. For example, it is an opening for introducing outside air such as running wind into the outer pipe 4 (specifically, the space between the outer peripheral surface of the inner pipe 2 and the inner peripheral surface of the outer pipe 4). The arrow b shown in FIG. 1 indicates the flow direction of the outside air introduced into the outer pipe 4. The shape, size, and the like of the outside air introduction portion 5 are not limited to those shown in FIG.

The flow of exhaust gas in the exhaust structure 100 configured as described above will be described below.

The exhaust gas flowing through the exhaust pipe 1 flows into the inner pipe 2. On the other hand, the outside air introduced from the outside air introduction portion 5 into the outer pipe 4 flows into the inner pipe 2 from each opening 3 of the inner pipe 2. Since each opening 3 has a shape inclined with respect to the axial direction of the inner pipe 2, the outside air becomes a swirling flow in the inner pipe 2. The swirling outside air is mixed with the exhaust gas, passes through the downstream end opening of the inner pipe 2, and is discharged into the atmosphere from the downstream end opening 4a of the outer pipe 4.

As described above, in the exhaust structure 100 of the present embodiment, by generating a swirling flow in the inner pipe 2, diffusion and heat dissipation of the exhaust gas are promoted, and the cooling performance of the exhaust gas can be further improved.

The number, shape, size, and position of the openings 3 are not limited to those shown in FIG. They may be determined so that the swirling flow is effectively generated in the inner pipe 2 based on the results of experiments and simulations carried out in advance.

Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the description of the above-described embodiment, and various modifications can be made without departing from the gist thereof. Hereinafter, a modified example will be described.

[Modification 1]
In the embodiment, the case where the inner pipe 2 has a shape having a uniform inner diameter from the upstream end to the downstream end has been described as an example, but the present invention is not limited to this. For example, the inner pipe 2 may have a shape in which the diameter is expanded from the upstream end to the downstream end. Similarly, the outer pipe 4 may also have a shape whose diameter is increased from the upstream end to the downstream end. Thereby, the diffusion effect and the heat dissipation effect of the exhaust gas can be further improved.

[Modification 2]
In the embodiment, a case where a plurality of openings 3 are provided on the outer peripheral surface of the inner pipe 2 has been given as an example, but the present invention is not limited to this. For example, one spiral opening along the axial direction of the inner pipe 2 may be provided on the outer peripheral surface of the inner pipe 2.

[Modification 3]
In the embodiment, the case where the inner pipe 2 is removable from the exhaust pipe 1 has been given as an example, but the present invention is not limited to this. For example, the inner pipe 2 may be integrally formed with the exhaust pipe 1. In other words, the inner pipe 2 may be a part of the exhaust pipe 1.

[Modification example 4]
In the embodiment, the tail pipe is used as an example of the inner pipe 2, and the exhaust diffuser is used as an example of the outer pipe 4, but the present invention is not limited to this. For example, both the inner pipe 2 and the outer pipe 4 may be components of the exhaust diffuser. In other words, the exhaust diffuser may be an exhaust diffuser having a double piping structure including an inner pipe 2 and an outer pipe 4.

The modified example has been described above. The above modified examples may be combined.

The exhaust structure of the present disclosure is useful for all techniques for discharging gas into the atmosphere.

1 Exhaust pipe 2 Inner pipe 3 Opening 4 Outer pipe 4a Downstream end opening of outer pipe 4 5 Outside air introduction part 100 Exhaust structure

Claims (5)

The exhaust pipe through which the exhaust gas discharged from the internal combustion engine flows, and
An inner pipe provided on the downstream side of the exhaust pipe and
It has an outer pipe provided so as to cover the inner pipe and provided with an outside air introduction portion for introducing outside air.
On the outer peripheral surface of the inner pipe,
An opening is provided to allow the outside air introduced from the outside air introduction portion to flow into the inner pipe.
The opening is
The shape is such that a swirling flow is generated in the inner pipe.
Exhaust structure. The opening is
A plurality of them are provided along the outer peripheral surface of the inner pipe.
The shape is inclined with respect to the axial direction of the inner pipe.
The exhaust structure according to claim 1. The inner tube
The shape is expanded from the upstream side to the downstream side.
The exhaust structure according to claim 1 or 2. The inner tube
It's a tail pipe,
The exhaust structure according to any one of claims 1 to 3. The outer tube is
Exhaust diffuser,
The exhaust structure according to any one of claims 1 to 4.

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