JP7205452B2 - exhaust passage - Google Patents

Description

The present invention relates to exhaust passages.

An exhaust pipe of an internal combustion engine is provided with a sensor for detecting oxygen concentration in the exhaust gas. In the operation control of the internal combustion engine, for example, the air-fuel ratio is controlled by adjusting the intake air amount and the fuel injection amount according to the detected oxygen concentration.
Exhaust gas from each cylinder flows into one exhaust pipe through an exhaust manifold. Since the flow of exhaust gas is highly directional in the downstream direction and tends to be uneven within the cross section of the exhaust pipe, it is being studied to provide a mechanism for stirring the exhaust gas before it reaches the sensor.

Patent Literature 1 discloses a dispersion plate in which two plates are combined as a dispersion plate for dispersing an exhaust flow.
Patent Literature 2 discloses providing a protrusion having a hole between a first exhaust pipe and a second exhaust pipe. According to Patent Document 2, it is described that when the exhaust gas passes through the vicinity of the protrusion, it becomes turbulent and diffuses.

JP 2016-79962 A JP 2014-126009 A

Since each of the dispersion plates and the like disclosed in Patent Documents 1 and 2 has a small aperture ratio, there is a problem that the pressure loss tends to increase. Moreover, since the dispersion plate of Patent Document 1 uses a plurality of plates, it is disadvantageous in terms of manufacturing cost and reliability. In addition, depending on the arrangement of the hole and the sensor, the protrusion of Patent Document 2 may reduce the flow rate of the gas per contact with the sensor, degrading the responsiveness of the sensor.

In order to solve the above problems, for example, a protrusion that is continuously provided in a part of the inner surface of the exhaust pipe in the circumferential direction, is inclined in the extending direction of the exhaust pipe, and has a smaller cross-sectional area toward the downstream side of the exhaust pipe. By forming the portion, it is conceivable to efficiently agitate the exhaust gas while suppressing the pressure loss in the exhaust pipe. However, forming the protrusion in the exhaust pipe may cause pressure loss in the protrusion.

The present invention solves such problems, and provides an exhaust passage having a high agitation effect while further suppressing pressure loss.

The exhaust passage according to this embodiment is
an exhaust pipe;
The exhaust passage is provided with a projecting portion continuously provided on the inner surface of the exhaust pipe in a partial range in the circumferential direction and inclined in the extending direction of the exhaust pipe and having a cross-sectional area that decreases toward the downstream side of the exhaust pipe. hand,
A plurality of through-holes penetrating the projecting portion are provided at an upstream end of the projecting portion,
It is characterized in that the area of the through hole farther from both ends in the circumferential direction of the protrusion is larger than the area of the through hole closer to the both ends.

ADVANTAGE OF THE INVENTION By this invention, the exhaust passage which has a high stirring effect can be provided, suppressing a pressure loss more.

FIG. 3 is a schematic side view showing an example of an exhaust passage according to the embodiment; FIG. 4 is a schematic side view showing an example of a protrusion; FIG. 4 is a schematic front view showing an example of a protrusion; FIG. 5 is a schematic side view showing another example of an exhaust passage; FIG. 10 is a schematic side view showing another example of the protrusion; FIG. 10 is a schematic side view showing another example of the protrusion;

Hereinafter, the present invention will be described through embodiments, but the invention according to the scope of claims is not limited to the following embodiments. Also, for clarity of explanation, the following description and drawings are simplified as appropriate. In this specification, the X-axis is taken downstream in the axial direction (extending direction) of the exhaust pipe, and the plane perpendicular to the X-axis is the YZ plane (also referred to simply as the cross section).

The exhaust passage 10 shown in the example of FIG. 1 is an exhaust passage suitably used for an internal combustion engine, and includes at least an exhaust pipe 11 (11A, 11B) and a projecting portion 22. It may be provided with the configuration of A plurality of through holes are formed in the projecting portion 22 . The protruding portion 22 is a tapered member that is inclined in the extending direction of the exhaust pipe, and is in contact with the exhaust pipe 11 at its upstream end. The projecting portion 22 has an inner surface formed continuously with the inner surface of the exhaust pipe 11 . The projecting portion 22 has a smaller cross-sectional area toward the downstream side of the exhaust pipe 11 . Here, the cross section of the projecting portion 22 refers to the arc-shaped cross section perpendicular to the axis of the exhaust pipe 11, and the cross-sectional area of the projecting portion 22 refers to the arc, the end point of the arc, and the center of the exhaust pipe 11. It refers to the area of a sector formed by connecting lines. The exhaust passage of the present embodiment has a high stirring effect while suppressing pressure loss. This will be described with reference to FIGS. 2 and 3. FIG.

2 and 3 are schematic diagrams for explaining a mechanism in which the projecting portion 22 stirs the exhaust gas. As shown in the example of FIG. 3, the projecting portion 22 is formed with a plurality of through holes 22a to 22h. As shown in the example of FIG. 2, a plurality of through holes 22a-22h are provided at the upstream end 25 of the protrusion 22 and pass through the protrusion 22. As shown in FIG.
As shown in the example of FIG. 2, the exhaust gas passes through the projecting portion 22 when flowing from upstream to downstream. Since the protruding portion 22 has a structure in which the cross-sectional area decreases toward the downstream side, the gas in the protruding portion 22 is pushed out of the protruding portion 22 toward the downstream side to generate the airflow indicated by the solid arrow. As shown in FIG. 3, this airflow is continuously generated over the entire area of the projecting portion 22 to form a swirling flow, and even after passing through the projecting portion 22, the exhaust gas is stirred throughout the pipe. As a result, the surface uniformity of the exhaust gas is improved, and the accuracy of measurement by the sensor is improved. Further, in the exhaust passage of the present embodiment, the opening of the projecting portion is relatively large, and the swirling flow described above spreads throughout the pipe, so that an increase in pressure loss can be suppressed.
Since a plurality of through-holes 22a to 22h are formed in the upstream end 25 of the projecting portion 22, part of the gas in the projecting portion 22 is pushed out of the projecting portion 22 through the plurality of through-holes 22a to 22h and is indicated by a dotted line arrow. The airflow shown is generated. As a result, the occurrence of pressure loss within the projecting portion 22 can be suppressed. As shown in the examples of FIGS. 2 and 3, the area of the through-holes farther from both ends (end points 26) in the circumferential direction of the protruding portion 22 is formed to be larger than the area of the through-holes closer to the both ends. Therefore, the amount of exhaust gas extruded from the through holes 22d and 22e is larger than the amount of exhaust gas extruded from the through holes 22a and 22h. As a result, it is possible to further suppress the occurrence of pressure loss in portions far from both circumferential ends of the projecting portion 22 . The airflow generated by the exhaust gas being pushed out from the plurality of through holes 22a to 22h collides with the swirling flow described above, and the exhaust gas is stirred. As a result, the surface uniformity of the exhaust gas is further improved.
As shown in the example of FIG. 2, the plurality of through holes 22a to 22h may be slits whose longitudinal direction is, for example, the direction in which the exhaust pipe extends. In this case, the slit length L of the through hole farther from both ends in the circumferential direction of the projecting portion 22 is formed to be longer than the slit length L of the through hole closer to the both ends. The number of through-holes formed in the protruding portion 22 is not particularly limited, and can be changed as appropriate according to the diameter of the exhaust pipe 11 or the like.

In this embodiment, as shown in the example of FIG. 1, the exhaust pipe 11 may be configured to include an upstream exhaust pipe 11A and a downstream exhaust pipe 11B. The exhaust pipe 11A is used with its downstream end connected to the upstream end of the exhaust pipe 11B. The method of connecting the exhaust pipes 11A and 11B is not particularly limited, and they may be connected using a connector 23 as shown in the example of FIG. 1, for example.
In the case of the configuration including the exhaust pipes 11A and 11B, the projecting portion 22 should be molded integrally with the upstream exhaust pipe 11A from the viewpoint of suppressing corrosion at the joint portion and improving the positional accuracy of the tip of the projecting portion 22. is preferred. When the projecting portion 22 is molded integrally with the exhaust pipe 11A, the exhaust pipe 11A is fitted into the exhaust pipe 11B so that the projecting portion 22 formed at the downstream end of the exhaust pipe 11A enters the upstream end of the exhaust pipe 11B. . As a method of integrally molding the projecting portion 22 with the exhaust pipe 11A, for example, pressing is performed to form the projecting portion 22 by bending the downstream end side of the exhaust pipe 11A. When the projecting portion 22 is formed integrally with the exhaust pipe 11A by press working, the projecting portion 22 does not need to be welded to the exhaust pipe 11A, so the occurrence of corrosion at the junction between the projecting portion 22 and the exhaust pipe 11A is suppressed. be. In addition, since welding distortion does not occur, the positional accuracy of the projecting portion 22 is improved.
When the projecting portion 22 is integrally formed with the exhaust pipe 11A by press working, as shown in the example of FIG. It is preferably formed in If the plurality of through-holes 22a to 22h are continuously formed from the main body of the exhaust pipe 11A to the protruding portion 22, the generation of wrinkles at the base of the protruding portion 22 is suppressed during press working. and the occurrence of gas leakage is suppressed.

The shape of the exhaust pipe 11B on the downstream side is not particularly limited, and may be a flexible pipe as shown in the example of FIG. 4, for example. In FIG. 4, illustration of the plurality of through holes 22a to 22h is omitted. When the inner diameter of the exhaust pipe 11B is smaller than the outer diameter of the exhaust pipe 11A as shown in the example of FIG. is desirable. Even in this case, if the plurality of through holes 22a to 22h are continuously formed from the main body of the exhaust pipe 11A to the protruding portion 22, it is possible to suppress the occurrence of wrinkles at the base of the protruding portion 22 during press working.

When the projecting portion 22 is molded integrally with the exhaust pipe 11A, as shown in the example of FIG. good. The arcuate portion 24 has a shape that is recessed toward the joint portion between the main body of the exhaust pipe 11A and the protruding portion 22 with respect to the imaginary straight line connecting both ends of the arcuate portion 24 . The arcuate portion 24 may be formed so as to connect the main body of the exhaust pipe 11A and the projecting portion 22 as shown in the example of FIG. may be formed so as to dent the upstream side of the . When the arcuate portion 24 is formed, it is possible to suppress formation resistance in the vicinity of the joint between the exhaust pipe 11A main body and the circumferential ends of the projecting portion 22 during press working, thereby suppressing the occurrence of wrinkles in the vicinity of the joint. can do. In addition, it is possible to reduce the concentrated stress in the vicinity of the joint when the exhaust gas passes through.

The exhaust passage of the present embodiment has a high stirring effect while suppressing pressure loss as described above, and can be suitably used as an exhaust passage of an internal combustion engine, for example.

10 exhaust passage, 11 (11A, 11B) exhaust pipe, 22 protrusion, 22a-22h multiple through holes, 23 connector, 24 arcuate portion, 25 upstream end, 26 end point.

Claims (1)

an exhaust pipe;
The exhaust passage is provided with a projecting portion continuously provided on the inner surface of the exhaust pipe in a partial range in the circumferential direction and inclined in the extending direction of the exhaust pipe and having a cross-sectional area that decreases toward the downstream side of the exhaust pipe. hand,
A plurality of through-holes penetrating the projecting portion are provided at an upstream end of the projecting portion,
The area of the through hole farther from both ends in the circumferential direction of the protrusion is larger than the area of the through hole closer to the both ends.
exhaust passage.

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