1. A tail pipe that constitutes a portion including an outlet of an exhaust flow path of a vehicle, the tail pipe comprising:

an outlet portion that is a tubular portion that is provided adjacent to a downstream side of a curved portion that forms a curved section in the exhaust gas flow path and that extends to the outlet along an axis that is linear;

an outlet inner side portion that is a portion included in the outlet portion and that extends from an inner starting position to an inner ending position along the axis toward the downstream side, wherein the inner starting position is located on the downstream side of an inner portion of the curved portion; and

an outlet outer side portion which is a portion included in the outlet portion and which extends from an outer starting position to an outer ending position along the axis toward the downstream side, wherein the outer starting position is located on the downstream side of an outer portion of the curved portion, and

the axis passes through the center of the inlet of the outlet portion,

the distance between each of the outlet inner side portion and the outlet outer side portion and the axis line, that is, the axial line distance increases toward the downstream side,

the rate of increase of the axial distance of the outlet inner side portion is greater than the rate of increase of the axial distance of the outlet outer side portion.

2. A tail pipe that constitutes a portion including an outlet of an exhaust flow path of a vehicle, the tail pipe comprising:

an outlet portion that is a tubular portion that is provided adjacent to a downstream side of a curved portion that forms a curved section in the exhaust gas flow path and that extends to the outlet along an axis that is linear;

an outlet inner side portion that is a portion included in the outlet portion and that extends from an inner starting position to an inner ending position along the axis toward the downstream side, wherein the inner starting position is located on the downstream side of an inner portion of the curved portion; and

an outlet outer side portion which is a portion included in the outlet portion and which extends from an outer starting position to an outer ending position along the axis toward the downstream side, wherein the outer starting position is located on the downstream side of an outer portion of the curved portion, and

the axis passes through the center of the inlet of the outlet portion,

the distance between the outlet inner side portion and the axis line, i.e. the axial line distance increases toward the downstream side,

the outer starting position is located at the end of the outlet section at the inlet side,

the outer end position is located at an end of the outlet portion at the outlet side,

the outlet outer portion extends toward the downstream side in a state where the axial distance is kept substantially constant.

3. A liner according to claim 1,

the inner and outer end positions are located at an end of the outlet portion at the outlet side.

4. A liner according to claim 1,

the outer end position is located at an end of the outlet portion at the outlet side,

the inner end position is a position on an upstream side of the outlet in the outlet portion,

the tail pipe further includes a downstream-side inner portion that is included in the outlet portion and extends from the inner end position to an end portion on the outlet side with the axial distance kept substantially constant.

5. A liner according to claim 1,

the inner and outer end positions are positions on an upstream side of the outlet in the outlet portion,

the tail pipe further comprises a downstream inner part and a downstream outer part,

the downstream-side inner portion is a portion included in the outlet portion, and extends from the inner end position to an end portion of the outlet side in a state where the axial distance is kept substantially constant;

the downstream-side outer portion is a portion included in the outlet portion, and the downstream-side inner portion extends from the outer end position to an end portion of the outlet side in a state where the axial distance is kept substantially constant.

6. A liner according to any one of claims 1 to 5,

a plane orthogonal to the axis is used as a reference orthogonal plane,

at least a part of the outlet is inclined with respect to the reference orthogonal plane so as to approach an upstream side as approaching the outlet inner side portion.

7. A liner according to any one of claims 1 to 6,

an end portion of the outlet portion on the outlet side is bent toward an outer side or an inner side of the outlet.

8. A tail pipe that constitutes a portion including an outlet of an exhaust flow path of a vehicle, the tail pipe comprising:

a curved portion that forms a curved section in the exhaust gas flow path;

an outlet portion that is a tubular portion that is disposed adjacent to a downstream side of the bend and extends along an axis to the outlet;

an outlet inner portion that is a portion extending from an inner starting position to an inner ending position along the axis toward the downstream side, wherein the inner starting position is located halfway an inner portion of the bend or the downstream side of the bend; and

an outlet outer side portion that is a portion extending from an outer starting position to an outer ending position along the axis toward the downstream side, wherein the outer starting position is located halfway of an outer portion of the curved portion or the downstream side of the curved portion, and

the axis passes through the center of the inlet of the outlet portion,

the distance between each of the outlet inner side portion and the outlet outer side portion and the axis line, that is, the axial line distance increases toward the downstream side,

the rate of increase of the axial distance of the outlet inner side portion is greater than the rate of increase of the axial distance of the outlet outer side portion.

9. A tail pipe that constitutes a portion including an outlet of an exhaust flow path of a vehicle, the tail pipe comprising:

a curved portion that forms a curved section in the exhaust gas flow path;

an outlet portion that is a tubular portion that is disposed adjacent to a downstream side of the bend and extends along an axis to the outlet;

an outlet inner portion that is a portion extending from an inner starting position to an inner ending position along the axis toward the downstream side, wherein the inner starting position is located halfway an inner portion of the bend or the downstream side of the bend; and

an outlet outer side portion that is a portion extending from an outer starting position to an outer ending position along the axis toward the downstream side, wherein the outer starting position is located halfway of an outer portion of the curved portion or the downstream side of the curved portion, and

the axis passes through the center of the inlet of the outlet portion,

the distance between the outlet inner side portion and the axis line, i.e. the axial line distance increases toward the downstream side,

the outer starting position is located halfway of the inner portion of the bend or an end of the outlet portion at the inlet side,

the outer end position is located at the end of the outlet side,

the outlet outer portion extends toward the downstream side with the axial distance kept substantially constant.

Background

There is known a technique of providing a diameter-enlarged portion at an outlet portion in a tail pipe having a bend, the outlet portion extending linearly from an end portion on a downstream side of the bend (for example, japanese patent laid-open No. 2000-248934). According to the above-described technology, the uniformization of the flow of the exhaust gas at the outlet portion can be promoted, and the noise can be suppressed.

Disclosure of Invention

Here, the flow velocity of the exhaust gas flowing through the periphery of the curved portion outside portion is larger than the flow velocity of the exhaust gas flowing through the periphery of the curved portion inside portion. Therefore, if the inclination of the portion of the enlarged diameter portion located on the downstream side of the outer portion of the bent portion is large, a phenomenon (hereinafter, referred to as separation) in which the distance between the flow path of the exhaust gas and the portion is large may occur. In other words, the peeling means a phenomenon in which the flow of the exhaust gas is separated from the wall surface of the enlarged diameter portion. Further, the separation may cause generation of a vortex flow near the wall surface of the enlarged diameter portion to generate an airflow sound, which may result in failure to sufficiently suppress noise generated by the exhaust gas.

In one aspect of the present disclosure, it is desirable to more suitably reduce noise generated by exhaust gas.

One aspect of the present disclosure is a tail pipe that constitutes a portion including an outlet of an exhaust gas flow path of a vehicle, and that is provided with an outlet portion, an outlet inner side portion, and an outlet outer side portion. The outlet portion is a tubular portion that is disposed adjacent to a downstream side of a curved portion that forms a curved section in the exhaust gas flow path, and that extends to the outlet along an axis that is linear. The outlet inner side portion is a portion included in the outlet portion, and extends from an inner starting position to an inner ending position along the axis toward the downstream side, wherein the inner starting position is located on the downstream side of the inner portion of the curved portion. The outlet outer side portion is a portion included in the outlet portion, and extends from an outer starting position to an outer ending position along the axis toward the downstream side, wherein the outer starting position is located on the downstream side of the outer portion of the bent portion. The axis passes through the center of the inlet of the outlet portion. Further, the axial distances, which are the distances between the respective outlet inner side portions and the respective outlet outer side portions from the axial line, increase toward the downstream side, and the rate of increase in the axial distance of the outlet inner side portion is greater than the rate of increase in the axial distance of the outlet outer side portion.

According to the above configuration, the inner space of the outlet portion is expanded toward the downstream side by the outlet inner portion and the outlet outer portion. Therefore, the exhaust gas whose flow velocity is increased by passing through the bent portion can be appropriately decelerated at the outlet portion. Thus, the generation of a vortex by the exhaust gas flowing out from the outlet can be suppressed, and the airflow sound can be reduced.

Further, the rate of increase in the axial distance of the outlet inner portion is greater than the rate of increase in the axial distance of the outlet outer portion, whereby the area of the periphery of the outlet inner portion (hereinafter referred to as inner area) is further enlarged than the area of the periphery of the outlet outer portion (hereinafter referred to as outer area) in the internal space of the outlet portion. Therefore, the exhaust gas having passed through the bent portion is urged toward the inner side area where the peeling is less likely to occur because the flow of the exhaust gas is gentle. As a result, the flow of the exhaust gas can be suppressed from being deviated to the outer region, and the flow velocity of the exhaust gas in the outer region can be reduced, thereby promoting the flow of the exhaust gas to be more uniform. This can suppress the generation of turbulence and reduce the flow noise.

Further, not only the flow velocity of the exhaust gas in the outer region is reduced, but also the rate of increase in the axial distance of the outlet outer side portion is smaller than the rate of increase in the axial distance of the outlet inner side portion, and therefore, the outlet outer side portion is gently away from the axial line as going toward the downstream side. As a result, the vortex flow can be suppressed from being generated in the vicinity of the wall surface of the outlet portion in the outer region, and the airflow sound can be reduced.

Therefore, noise generated by the exhaust gas can be reduced more appropriately.

Further, one aspect of the present disclosure is a tail pipe that constitutes a portion including an outlet of an exhaust gas flow path of a vehicle, and that is provided with an outlet portion, an outlet inner side portion, and an outlet outer side portion. The outlet portion is a tubular portion that is disposed adjacent to a downstream side of a curved portion that forms a curved section in the exhaust gas flow path, and that extends to the outlet along an axis that is linear. The outlet inner side is a portion included in the outlet portion, and extends from an inner start position located on a downstream side of an inner portion of the curved portion to an inner end position along the axis toward a downstream side. The outlet outer side portion is a portion included in the outlet portion, and extends from an outer starting position located on a downstream side of an outer portion of the curved portion to an outer ending position along the axis toward a downstream side. The axis passes through the center of the inlet of the outlet portion. Further, the distance between the outlet inner side portion and the axis, that is, the axial distance increases toward the downstream side. Furthermore, the outer starting position is located at an end of the outlet section on the inlet side and the outer end position is located at an end of the outlet section on the outlet side. The outlet outer portion extends downstream so as to keep the axial distance substantially constant.

According to the above configuration, the inner space of the outlet portion is expanded toward the downstream side by the outlet inside portion. Therefore, the exhaust gas whose flow velocity is increased by passing through the bent portion can be appropriately decelerated at the outlet portion. Thus, the generation of a vortex by the exhaust gas flowing out from the outlet can be suppressed, and the airflow sound can be reduced.

Further, since the outlet outer portion extends in a state in which the axial distance is kept substantially constant, an inner area of the periphery of the outlet inner portion is further enlarged than an outer area of the periphery of the outlet outer portion in the inner space of the outlet portion. Therefore, the exhaust gas having passed through the bent portion is urged toward the inner side area where the peeling is less likely to occur because the flow of the exhaust gas is gentle. As a result, the flow of the exhaust gas can be suppressed from being deviated to the outer region, and the flow velocity of the exhaust gas in the outer region can be reduced, thereby promoting the flow of the exhaust gas to be more uniform. This suppresses the generation of turbulence and reduces the airflow sound.

Further, not only the flow velocity of the exhaust gas in the outer region is reduced, but also the axial distance of the outlet outer portion is kept substantially constant. Therefore, the exhaust gas flowing through the outer region can be suppressed from separating from the wall surface of the outlet portion, and as a result, the vortex flow can be suppressed from being generated in the vicinity of the wall surface of the outlet portion in the outer region, and the airflow sound can be reduced.

Therefore, noise generated by the exhaust gas can be reduced more appropriately.

Furthermore, the inner end position as well as the outer end position may be located at an end of the outlet section at the outlet side.

According to the above structure, the inner space is expanded by the outlet inner side portion and the outlet outer side portion at the portion to the outlet in the outlet portion. Therefore, the exhaust gas whose flow velocity is increased by passing through the bent portion can be further decelerated at the outlet portion, and the airflow sound can be further reduced.

Further, at a portion to the outlet in the inner space of the outlet portion, an inner area of a periphery of the outlet inner portion is further enlarged than an outer area of a periphery of the outlet outer portion. Therefore, the exhaust gas having passed through the bent portion is further urged toward the inner region. As a result, the flow of the exhaust gas can be further suppressed from being deviated to the outer region. This can further suppress the generation of turbulence and reduce the airflow sound.

Further, the outlet outer side portion is gently distant from the axis line toward the downstream side until the outlet. Therefore, the separation of the exhaust gas flowing through the outer region from the wall surface of the outlet portion can be more favorably suppressed, and as a result, the airflow sound can be further reduced.

Further, the outer end position may be located at an end portion of the outlet portion on the outlet side, and the inner end position may be a position on an upstream side of the outlet in the outlet portion. The tail pipe may further include a downstream inner portion included in the outlet portion, and the downstream inner portion may extend from the inner end position to the end of the outlet side with the axial distance kept substantially constant.

According to the above structure, the inner space is expanded by the outlet outside portion at the portion of the outlet portion to the outlet. Therefore, the exhaust gas whose flow velocity is increased by passing through the bent portion can be further decelerated at the outlet portion, and the airflow sound can be further reduced.

Further, the outlet outer side portion is gently distant from the axis line toward the downstream side until the outlet. Therefore, the separation of the exhaust gas flowing through the outer region from the wall surface of the outlet portion can be more favorably suppressed, and as a result, the airflow sound can be further reduced.

Further, a downstream-side inner portion whose distance from the axis is kept substantially constant is formed at a portion of the downstream side of the outlet inner portion including the outlet. Therefore, the molding of the outlet portion is easily performed.

Further, the inner end position and the outer end position may be positions on an upstream side of the outlet portion. The tail pipe may further include a downstream inner portion and a downstream outer portion. The downstream-side inner portion may be a portion included in the outlet portion, the downstream-side inner portion extending from the inner end position to an end of the outlet side in such a manner that the axial distance is kept substantially constant. Further, the downstream-side outer side portion may be a portion included in the outlet portion, and the downstream-side inner side portion may extend from the outer end position to an end portion of the outlet side in such a manner that the axial distance is kept substantially constant.

According to the above configuration, the downstream-side inner portion and the downstream-side outer portion, whose distances from the axis are kept substantially constant, are formed at the portion including the outlet on the downstream side of the outlet inner portion and the portion including the outlet on the downstream side of the outlet outer portion, respectively. Therefore, the molding of the outlet portion is easily performed.

Further, a plane orthogonal to the axis may be used as the reference orthogonal plane. At least a part of the outlet may be inclined with respect to the reference orthogonal plane so as to approach the upstream side as approaching the outlet inner side portion.

According to the above structure, since the outlet is inclined, the exhaust gas flowing through the inner area of the inner space of the outlet portion around the inner side portion of the outlet portion flows out from the outlet to the outside earlier. Therefore, the exhaust gas is urged toward the inner region in the internal space of the outlet portion, and the flow of the exhaust gas is suppressed from being deviated to the outer region. As a result, the generation of turbulence and/or peeling can be suppressed, and the airflow noise can be reduced.

Further, an end of the outlet portion at the outlet side may be bent toward an outer side or an inner side of the outlet.

According to the above configuration, it is possible to suppress the occurrence of injury or the like due to contact with the outlet of the tail pipe.

One aspect of the present disclosure is a tail pipe that constitutes a portion including an outlet of an exhaust flow path of a vehicle, and that is provided with a bent portion, an outlet inner portion, and an outlet outer portion. The bent portion forms a bent section in the exhaust gas flow path. The outlet portion is a tubular portion that is disposed adjacent to a downstream side of the bend and extends along the axis to the outlet. The outlet inner portion is a portion extending from an inner starting position located midway in an inner portion of the curved portion or on a downstream side of the curved portion toward a downstream side along the axis to an inner ending position. The outlet outer portion is a portion extending from an outer starting position located in the middle of an outer portion of the curved portion or on the downstream side of the curved portion to an outer ending position along the axis toward the downstream side. Further, the axis passes through the center of the inlet of the outlet portion. Further, the axial distances, which are the distances between the respective outlet inner side portions and the respective outlet outer side portions from the axial line, increase toward the downstream side, and the rate of increase in the axial distance of the outlet inner side portion is greater than the rate of increase in the axial distance of the outlet outer side portion.

According to the above configuration, the inner space of the outlet portion is expanded toward the downstream side by the outlet inner portion and the outlet outer portion. This can reduce the airflow noise while suppressing the generation of a vortex by the exhaust gas flowing out from the outlet. Further, since the rate of increase in the axial distance of the outlet inner portion is greater than the rate of increase in the axial distance of the outlet outer portion, the flow of the exhaust gas can be suppressed from being deviated to the outer region. Thereby suppressing the generation of turbulence and reducing the airflow sound. Further, since the rate of increase in the axial distance of the outlet outer portion is smaller than the rate of increase in the axial distance of the outlet inner portion, separation of the exhaust gas flowing through the outer region from the wall surface of the outlet portion can be suppressed, and as a result, generation of a vortex flow in the vicinity of the wall surface of the outlet portion in the outer region can be suppressed, and airflow noise can be reduced. Therefore, noise generated by the exhaust gas can be reduced more appropriately.

Further, one aspect of the present disclosure is a tail pipe that constitutes a portion including an outlet of an exhaust gas flow path of a vehicle, and that is provided with a bent portion, an outlet inner portion, and an outlet outer portion. The bent portion forms a bent section in the exhaust gas flow path. The outlet portion is a tubular portion that is disposed adjacent to a downstream side of the bend and extends along the axis to the outlet. The outlet inner portion is a portion extending from an inner starting position located midway in an inner portion of the curved portion or on a downstream side of the curved portion toward a downstream side along the axis to an inner ending position. The outlet outer portion is a portion extending from an outer starting position located in the middle of an outer portion of the curved portion or on the downstream side of the curved portion to an outer ending position along the axis toward the downstream side. Further, the axis passes through the center of the inlet of the outlet portion. Further, the distance between the outlet inner side portion and the axis, that is, the axial distance increases toward the downstream side. Further, the outer starting position is located halfway in the inner portion of the bent portion or the end portion of the outlet portion on the inlet side, and the outer ending position is located at the end portion on the outlet side. The outlet outer portion extends toward the downstream side with the axial distance kept substantially constant.

According to the above configuration, the inner space of the outlet portion is expanded toward the downstream side by the outlet inside portion. This can reduce the airflow noise while suppressing the generation of a vortex by the exhaust gas flowing out from the outlet. Further, since the outlet outer portion extends in a state where the axial distance is kept substantially constant, the flow of the exhaust gas can be suppressed from being deviated to the outer region. This can suppress the generation of turbulence and reduce the flow noise. Further, since the axial distance of the outlet outer portion is kept substantially constant, separation of the exhaust gas flowing through the outer region from the wall surface of the outlet portion can be suppressed, and as a result, generation of a vortex flow in the vicinity of the wall surface of the outlet portion in the outer region can be suppressed, and the airflow sound can be reduced. Therefore, noise generated by the exhaust gas can be reduced more appropriately.

Drawings

Fig. 1 is a cross-sectional view of a tail pipe of embodiment 1 taken along a reference plane.

Fig. 2 is a sectional view II-II of fig. 1.

Fig. 3 is a sectional view III-III of fig. 1.

Fig. 4 is a cross-sectional view of the tail pipe of embodiment 2 taken along a reference plane.

Fig. 5 is a V-V sectional view of fig. 4.

Fig. 6 is a cross-sectional view VI-VI of fig. 4.

Fig. 7 is a cross-sectional view of the tail pipe of embodiment 3 taken along a reference plane.

Fig. 8 is a sectional view VIII-VIII of fig. 7.

Fig. 9 is a cross-sectional view IX-IX of fig. 7.

Fig. 10 is a cross-sectional view of the tail pipe of embodiment 4 taken along a reference plane.

Fig. 11 is a cross-sectional view of the tail pipe of embodiment 5 taken along a reference plane.

Fig. 12 is a cross-sectional view of the tail pipe of embodiment 6 taken along a reference plane.

Fig. 13 is a cross-sectional view XIII-XIII of fig. 12.

Fig. 14 is a cross-sectional view XIV-XIV of fig. 12.

Detailed Description

Embodiments of the present disclosure are described below with reference to the drawings.

The embodiments of the present disclosure are not limited to the following embodiments, and various embodiments may be adopted within the technical scope of the present disclosure.

[ embodiment 1 ]

[1. Overall Structure ]

The curved tail pipe 1 in embodiment 1 constitutes a portion including an exhaust outlet in an exhaust gas flow path extending from an engine of a vehicle (see fig. 1 to 3). An inlet 10 of the tail pipe 1 is connected to a muffler, an exhaust pipe, or the like, and exhaust gas flowing into the tail pipe 1 from the inlet 10 is discharged to the outside of the vehicle through an outlet 11. The tail pipe 1 extends along a center line 12 of a curve included in a reference plane 13, and the tail pipe 1 includes a curve 2 and an outlet 3.

The curved portion 2 is a tubular portion forming a curved section of the exhaust gas flow path. In the present embodiment, as one example, the bent portion 2 is bent in such a manner that an angle between an axis orthogonal to the inlet and an axis orthogonal to the outlet is substantially 90 °. However, without being limited thereto, the angle between the axes may be an angle other than 90 °. Further, the tubular portion where the axes intersect in a curved manner may correspond to a curved portion. As an example, a cross section orthogonal to the center line 12 in the curved portion 2 is substantially circular. Hereinafter, a portion of the bent portion 2 that separates an inner region and an outer region of the exhaust gas flow path is referred to as an inner portion 20, and a portion that separates the outer region and the outer region of the exhaust gas flow path is referred to as an outer portion 21. In other words, the inner portion 20 is a portion located inward of a portion of the curved portion 2 that intersects the reference plane 13, and the outer portion 20 is a portion located outward of the intersecting portion.

The outlet portion 3 is a tubular portion provided adjacent to the downstream side of the bent portion 2 and extending along the axis 31 to the outlet 11. Further, the axis 31 is included in the center line 12, passes through the center of the inlet 30, which is an opening on the upstream side of the outlet portion 3, and extends linearly to the downstream side. Further, as an example, the inlet 30 is substantially circular, and the inlet 30 is connected to the downstream side opening in the curved portion 2. Further, as one example, the outlet 11 is substantially circular.

[2. Outlet section ]

The outlet portion 3 includes an outlet inner portion 4 and an outlet outer portion 5 included in a side wall 32 of the outlet portion 3.

The outlet inner portion 4 extends from an inner start position 40 located on the downstream side of the inner portion 20 of the curved portion 2 to an inner end position 41 on the downstream side along the axis 31, and the outlet inner portion 4 is located farther from the axis 31 toward the downstream side. Therefore, the outlet inner portion 4 is formed such that the area of a cross section orthogonal to the axis 31 (hereinafter referred to as an outlet cross-sectional area) of the outlet portion 3 increases toward the downstream side. In embodiment 1, as an example, the inside start position 40 is located at the end of the outlet portion 3 on the inlet 30 side, and the inside end position 41 is located at the end of the outlet portion 3 on the outlet 11 side of the tail pipe 1 (refer to fig. 1). Further, the inside starting position 40 and the inside ending position 41 are located at the innermost position in the outlet inner portion 4.

The outlet outer side portion 5 extends from an outer starting position 50 located on the downstream side of the outer side portion 21 of the curved portion 2 to an outer ending position 51 toward the downstream side along the axis 31, and the outlet outer side portion 5 is away from the axis 31 as going toward the downstream side. Therefore, the outlet outer portion 5 is also formed such that the outlet portion sectional area increases toward the downstream side. In embodiment 1, as an example, the outside start position 50 is located at the end of the outlet portion 3 on the inlet 30 side, and the outside end position 51 is located at the end of the outlet portion 3 on the outlet 11 side of the tail pipe 1. Further, the outer starting position 50 and the outer ending position 51 are located at the outermost positions in the outlet outer portion 5.

That is, the outlet inner side portion 4 includes a portion connected to the inner side portion 20 of the curved portion 2 in the intersecting portion, and the outlet outer side portion 5 includes a portion connected to the outer side portion 21 of the curved portion 2 in the intersecting portion, which is the portion intersecting the reference plane 13 in the outlet portion 3. The outlet inner portion 4 and the outlet outer portion 5 are opposed to each other across the axis 31 in the width direction of the outlet portion 3 over substantially the entire area. Further, the direction in which the inside starting position 40 and the outside starting position 50 oppose each other, and the direction in which the inside ending position 41 and the outside ending position 51 oppose each other are both substantially coincident with the width direction of the outlet portion 3. The width direction refers to a direction of the width of the exhaust gas flow path formed by the outlet portion 3, and is a direction substantially orthogonal to the axis 31.

Specifically, as an example, a cross section (hereinafter referred to as an orthogonal cross section) orthogonal to the axis 31 in the outlet inner portion 4 extends in a substantially circular arc shape over approximately 45 ° or so, in such a manner as to be substantially line-symmetrical about the reference plane 13 (see fig. 2 and 3). In addition, as an example, the outlet outer portion 5 extends in a substantially circular arc shape in a range of about 180 ° in orthogonal cross section, in such a manner as to be substantially line-symmetrical about the reference plane 13.

Further, a cross section of the outlet inner 4 including the axis 31 (hereinafter referred to as an axial cross section) extends substantially linearly with an inclination angle β ° with respect to the axis 31 (see fig. 1). Further, the axial cross section of the outlet outer 5 extends substantially linearly with an inclination angle α ° with respect to the axis 31. Furthermore, the angle β ° of the outlet inner side 4 is greater than the angle α ° of the outlet outer side 5.

Here, the shortest distance between any portion of the side wall 32 of the outlet portion 3 and the axis 31 is defined as an axial distance. Further, the axial distance of the outlet inner side portion 4 at the inner starting position 40 is set to the 1 st axial distance 42, and the axial distance of the outlet inner side portion 4 at the inner ending position 41 is set to the 2 nd axial distance 43. Further, the axial distance of the outlet outer portion 5 at the outer starting position 50 is set to the 3 rd axial distance 52, and the axial distance of the outlet outer portion 5 at the outer ending position 51 is set to the 4 th axial distance 53. Further, a case is conceivable in which a portion of the outlet inner side portion 4 located at the inner starting position 40 or the inner ending position 41 and a portion of the outlet outer side portion 5 located at the outer starting position 50 or the outer ending position 51 have a certain area. Further, for example, when the portion is provided with irregularities, the axial distance of the portion is not fixed. In the above case, for example, the average value or the minimum value of the shortest distances between the portion and the axis 31 may be set to the 1 st to 4 th axial distances.

The value obtained by subtracting the 1 st axial distance 42 from the 2 nd axial distance 43 is defined as an inner difference, and the value obtained by subtracting the 3 rd axial distance 52 from the 4 th axial distance 53 is defined as an outer difference. The length from the inner starting position 40 to the inner end position 41 along the axis 31 is defined as the inner distance. The length from the outer starting position 50 to the outer end position 51 along the axis 31 is defined as an outer distance.

The inboard difference is greater than the outboard difference. Further, a value obtained by dividing the inside difference by the inside distance (hereinafter referred to as an inside increase rate) is larger than a value obtained by dividing the outside difference by the outside distance (hereinafter referred to as an outside increase rate). That is, the axial distance of the outlet inner portion 4 and the axial distance of the outlet outer portion 5 increase toward the downstream side. Moreover, the rate of increase in the axial distance of the outlet inner side portion 4 is greater than the rate of increase in the axial distance of the outlet outer side portion 5 over the entire area of the outlet inner side portion 4 and the entire area of the outlet outer side portion 5. Therefore, the outlet inner portion 4 makes the ratio of the outlet portion sectional area increasing toward the downstream side larger than the ratio of the outlet outer portion 5 making the outlet portion sectional area increasing toward the downstream side.

[2 nd embodiment ]

The outlet portion 3 of the tail pipe 1 according to embodiment 2 is different from that according to embodiment 1, and the other portions have the same configuration as that of embodiment 1. Differences from embodiment 1 in tail pipe 1 of embodiment 2 will be described below.

The outlet portion 3 includes an outlet inner portion 6, a downstream inner portion 33, and an outlet outer portion 5 (see fig. 4 to 6) similar to that of embodiment 1. Further, the outlet outer portion 5, the outlet inner portion 6, and the downstream inner portion 33 are all included in the side wall 32 of the outlet portion 3.

As in embodiment 1, the outlet inner side portion 6 extends from the inner starting position 60 toward the downstream side to the inner ending position 61, and the outlet inner side portion 6 is farther from the axis 31 toward the downstream side. In embodiment 2, as an example, the inside start position 60 is located at the end of the outlet portion 3 on the inlet 30 side, and the inside end position 61 is located on the upstream side of the outlet 11 side of the tail pipe 1. More specifically, as one example, the inner end position 61 is located at a position on the upstream side than the center of the outlet portion 3 in the flow direction.

The outlet inner portion 6 and the outlet outer portion 5 face each other in the width direction of the outlet portion 3 with the axis 31 interposed therebetween. Further, the direction in which the inside home position 60 and the outside home position 50 oppose each other substantially coincides with the width direction of the outlet portion 3. The inner end position 61 is located upstream of the outer end position 51.

As an example, the outlet inner 6 has a cross section perpendicular to the outlet inner side portion, which extends in a substantially circular arc shape over an angle of about 45 ° as in embodiment 1: substantially line-symmetrical with respect to the reference plane 13 (see fig. 5). Further, as in embodiment 1, the axial cross section of the outlet inner 6 extends substantially linearly with an inclination angle β ° with respect to the axis 31 (see fig. 4). The angle β ° of the outlet inner 4 is greater than the angle α ° of the outlet outer 5.

Further, the 1 st to 4 th axial distances 62, 63, 52, 53 in the axial cross section of the inside portion 6 and the outside portion 5 are determined in the same manner as in embodiment 1. Then, in the same manner as in embodiment 1, the inside difference, the outside difference, the inside increase rate, and the outside increase rate are calculated from the 1 st to 4 th axial distances 62, 63, 52, and 53, respectively. In embodiment 2, the inside difference is also larger than the outside difference, and the inside increase rate is also larger than the outside increase rate. That is, in embodiment 2, the axial distance of the outlet inner portion 6 and the axial distance of the outlet outer portion 5 also increase toward the downstream side. Moreover, the rate of increase in the axial distance of the outlet inner side portion 6 is greater than the rate of increase in the axial distance of the outlet outer side portion 5 over the entire area of the outlet inner side portion 6 and the entire area of the outlet outer side portion 5.

On the other hand, the downstream-side inner portion 33 extends along the axis 31 from the inner end position 61 to an end portion of the outlet portion 3 on the outlet 11 side of the tail pipe 1 with the axial distance kept substantially constant. That is, the downstream-side inner portion 33 extends from the inner end position 61 to the end on the outlet 11 side as going toward the downstream side neither away from nor close to the axis 31. Specifically, as an example, the downstream-side inner portion 33 extends in a substantially circular arc shape in a range of approximately 45 ° in orthogonal cross section, as follows: substantially line-symmetrical with respect to the reference plane 13 (see fig. 6). The axial cross section of the downstream-side inner portion 33 extends substantially linearly so as to be substantially parallel to the axis 31 (see fig. 4).

[ embodiment 3 ]

The outlet portion 3 of the tail pipe 1 of embodiment 3 is different from that of embodiment 1, and the other portions have the same configuration as that of embodiment 1. Differences from embodiment 1 in tail pipe 1 of embodiment 3 will be described below.

The outlet portion 3 has an outlet inner portion 6 and a downstream inner portion 33, and an outlet outer portion 7 and a downstream outer portion 34 (see fig. 7 to 9), which are similar to those of embodiment 2. Further, the outlet outer portion 7, the outlet inner portion 6, the downstream inner portion 33, and the downstream outer portion 34 are all included in the side wall 32 of the outlet portion 3.

As in embodiment 1, the outlet outer side portion 7 extends from the outer starting position 70 toward the downstream side to the outer ending position 71, and the outlet outer side portion 7 is farther from the axis 31 toward the downstream side. In embodiment 3, as an example, the outside start position 70 is located at the end of the outlet portion 3 on the inlet 30 side, and the outside end position 71 is located on the upstream side of the outlet 11 of the tail pipe 1. More specifically, as one example, the outside end position 71 is located at a position on the upstream side than the center of the outlet portion 3 in the flow direction.

The outlet inner portion 6 and the outlet outer portion 7 are opposed to each other across the axis 31 in the width direction of the outlet portion 3 over substantially the entire area. Further, the direction in which the inside starting position 60 and the outside starting position 70 are opposed to each other, and the direction in which the inside ending position 61 and the outside ending position 71 are opposed to each other are both substantially coincident with the width direction of the outlet portion 3.

Further, as an example, the orthogonal cross section of the outlet outer portion 7 is substantially circular in shape extending over approximately 180 ° as in embodiment 1, in such a manner that: substantially line-symmetrical with respect to the reference plane 13 (see fig. 8). Further, as in embodiment 1, the axial cross section of the outlet outer 7 extends substantially linearly with an inclination angle α ° with respect to the axis 31 (see fig. 7). Moreover, the angle β ° of the outlet inner side 6 is greater than the angle α ° of the outlet outer side 7.

Further, the 1 st to 4 th axial distances 62, 63, 72, 73 in the axial cross section of the inside portion 6 and the outside portion 7 are determined in the same manner as in embodiment 1. Then, in the same manner as in embodiment 1, the inner side difference, the outer side difference, the inner side increase rate, and the outer side increase rate are calculated from the 1 st to 4 th axial distances 62, 63, 72, and 73, respectively. In embodiment 3, the inside difference is also greater than the outside difference, and the inside increase rate is also greater than the outside increase rate. That is, in embodiment 3, the axial distance of the outlet inner portion 6 and the axial distance of the outlet outer portion 7 also increase toward the downstream side. Moreover, the rate of increase in the axial distance of the outlet inner portion 6 is also greater than the rate of increase in the axial distance of the outlet outer portion 7 over the entire area of the outlet inner portion 6 and the entire area of the outlet outer portion 7.

On the other hand, the downstream-side inner portion 34 extends along the axis 31 from the outer end position 71 to the end portion of the outlet portion 3 on the outlet 11 side of the tail pipe 1 with the axial distance kept substantially constant. That is, the downstream-side inner portion 34 extends from the inner end position 71 to the end on the outlet 11 side as going toward the downstream side neither away from nor close to the axis 31. Specifically, as an example, the downstream-side inner portion 34 extends in a substantially circular arc shape in a range of approximately 180 ° in orthogonal cross section, as follows: substantially line-symmetrical with respect to the reference plane 13 (see fig. 9). The axial cross section of the downstream outer portion 34 extends substantially linearly so as to be substantially parallel to the axis 31 (see fig. 7).

[ 4 th embodiment ]

The outlet 14 of the tail pipe 1 according to embodiment 4 is different from that of embodiment 1, and the other parts have the same configuration as that of embodiment 1 (see fig. 10). Differences from embodiment 1 in tail pipe 1 of embodiment 4 will be described below.

The outlet portion 3 of the tail pipe 1 according to embodiment 4 includes an outlet inner portion 4 and an outlet outer portion 5 similar to those of embodiment 1. The outlet 14 extends substantially in a planar shape, and the entire area of the outlet 14 is inclined with respect to the reference orthogonal plane 15 so as to be closer to the outlet inner side portion 4 and more toward the upstream side. The reference orthogonal surface 15 is a plane orthogonal to the axis 31.

However, the present invention is not limited to this, and a partial region of the outlet 14 may be inclined with respect to the reference orthogonal surface 15 so as to be closer to the outlet inner side portion 4 and more toward the upstream side. In embodiments 2 and 3 or embodiments 5 and 6 to be described later, the outlet of the tail pipe 1 may have the same configuration as that of embodiment 4.

[ 5 th embodiment ]

The tail pipe 1 of embodiment 5 differs from embodiment 1 in the configuration of the end portion on the outlet 11 side, and has the same configuration as that of embodiment 1 in other portions (see fig. 11). Differences from embodiment 1 in tail pipe 1 of embodiment 5 will be described below.

The outlet portion 3 of the tail pipe 1 of embodiment 5 includes an outlet inner portion 4 and an outlet outer portion 5 similar to those of embodiment 1. A curled portion 16 is formed around the entire periphery of the edge portion surrounding the outlet 11. That is, the edge of the outlet 11 is bent into a C-shape toward the outside of the outlet 11, and the bent portion 16 is formed into a tubular shape.

Further, the curled portion 16 may be formed not to be tubular but by slightly bending the edge portion of the outlet 11. In embodiments 2 to 4 or embodiment 6 described later, the same curled portion 16 as in embodiment 5 may be formed at the edge portions of the outlets 11 and 14 of the tail pipe 1. Further, the curled portion may be formed by bending an edge portion of the outlet 11 toward the inside, for example. In this case, it is preferable that the edge of the outlet 11 is expanded in diameter and a curved curl is formed inside so that the exhaust flow path formed by the outlet 3 is not narrowed around the outlet 11.

[ 6 th embodiment ]

The outlet portion 3 of the tail pipe 1 according to embodiment 6 is different from that according to embodiment 1, and the other portions have the same configuration as that of embodiment 1 (see fig. 11). Differences from embodiment 1 in tail pipe 1 of embodiment 6 will be described below.

The outlet portion 3 includes an outlet outer portion 8 and an outlet inner portion 4 (see fig. 12 to 14) similar to those of embodiment 1. Further, the outlet inner side portion 4 and the outlet outer side portion 8 are included in the side wall 32 of the outlet portion 3.

The outlet outer portion 8 extends downstream from the outer starting position 80 to the outer ending position 81 with the axial distance kept substantially constant. That is, the outlet outer portion 8 extends from the outer start position 80 to the outer end position 81 (see fig. 12) as it goes toward the downstream side without moving away from or approaching the axis 31. In embodiment 6, as an example, the outside start position 80 is located at the end of the outlet portion 3 on the inlet 30 side, and the outside end position 81 is located at the end of the outlet portion 3 on the outlet 11 side of the tail pipe 1.

The outlet inner portion 4 and the outlet outer portion 8 are opposed to each other across the axis 31 in the width direction of the outlet portion 3 over substantially the entire area. Further, the direction in which the inside starting position 40 and the outside starting position 80 oppose each other, and the direction in which the inside ending position 41 and the outside ending position 81 oppose each other are both substantially coincident with the width direction of the outlet portion 3.

Further, as an example, the outlet outer portion 8 extends in a substantially circular arc shape over an orthogonal cross section of approximately 180 ° in such a manner that: substantially line-symmetrical with respect to the reference plane 13 (see fig. 13 and 14). The axial cross section of the outlet outer 8 extends substantially linearly so as to be substantially parallel to the axis 31 (see fig. 12)

Further, the 1 st to 4 th axial distances 42, 43, 82, 83 in the axial cross section of the inside portion 4 and the outside portion 8 are determined in the same manner as in embodiment 1. Then, in the same manner as in embodiment 1, the inner side difference, the outer side difference, the inner side increase rate, and the outer side increase rate are calculated from the 1 st to 4 th axial distances 42, 43, 82, and 83, respectively.

In embodiment 6, since the outlet outer 8 extends toward the downstream side with the axial distance kept substantially constant, the angle α ° of the outlet outer 8 with respect to the axis 31 is 0. On the other hand, the axial distance of the outlet inner 4 increases toward the downstream side. Thus, the angle β ° of the outlet inner side 4 with respect to the axis 31 is greater than the angle α ° of the outlet outer side 8 with respect to the axis 31. The outer side difference and the outer side increase rate of the outlet outer portion 8 are substantially 0. Therefore, in embodiment 6, the inside difference is also larger than the outside difference, and the inside increase rate is also larger than the outside increase rate. The rate of increase in the axial distance of the outlet inner 6 is greater than the rate of increase in the axial distance of the outlet outer 7 over the entire area of the outlet inner 6 and the entire area of the outlet outer 7.

Furthermore, the tail pipe 1 according to embodiments 2 to 5 may be provided with the outlet outer portion 8 according to embodiment 6.

[ Effect ]

(1) According to embodiment 1, the inner space of the outlet portion 3 is expanded toward the downstream side by the outlet inner side portion 4 and the outlet outer side portion 5 at the portion to the outlet 11 in the outlet portion 3. Therefore, the exhaust gas whose flow velocity is increased by passing through the bent portion 2 can be appropriately decelerated at the outlet portion 3. It is thereby possible to suppress the generation of a vortex by the exhaust gas flowing out from the outlet 11 and reduce the airflow sound.

Further, at a portion to the outlet 11 in the outlet portion 3, the rate of increase in the axial distance of the outlet inner side portion 4 is larger than the rate of increase in the axial distance of the outlet outer side portion 5. Thereby, in the internal space of the outlet portion 3, the inner area around the outlet inner portion 4 is further enlarged than the outer area around the outlet outer portion 5. Therefore, the exhaust gas having passed through the bent portion 2 is urged toward the inner side area where the peeling is less likely to occur because the flow of the exhaust gas is gentle. As a result, the flow of the exhaust gas can be suppressed from being deviated to the outer region, and the flow velocity of the exhaust gas in the outer region can be reduced, thereby promoting the flow of the exhaust gas to be more uniform. This can suppress the generation of turbulence and reduce the flow noise.

Further, not only the flow velocity of the exhaust gas in the outer region is reduced, but also the rate of increase in the axial distance of the outlet outer portion 5 is smaller than the rate of increase in the axial distance of the outlet inner portion 4 until the outlet 11, and therefore the outlet outer portion 5 is gently distanced from the axis 31 as it goes to the downstream side. Accordingly, separation of the exhaust gas flowing through the outer region from the wall surface of the outlet portion 3 can be suppressed, and as a result, generation of a vortex flow in the vicinity of the wall surface of the outlet portion 3 in the outer region can be suppressed, and the airflow sound can be reduced.

Therefore, noise generated by the exhaust gas can be reduced more appropriately.

(2) Further, in embodiment 2, a downstream side inner portion 33, the distance from the axis 31 of which is kept substantially constant, is formed at a portion of the downstream side of the outlet inner portion 6 including the outlet 11. Therefore, the molding of the outlet portion 3 is easily performed.

(3) Further, in embodiment 3, a downstream side inner portion 33 and a downstream side outer portion 34, whose distances from the axis 31 are kept substantially constant, are formed at a portion including the outlet 11 on the downstream side of the outlet inner portion 6 and at a portion including the outlet 11 on the downstream side of the outlet outer portion 7, respectively. Therefore, the molding of the outlet portion 3 is easily performed.

(4) Further, in embodiment 4, since the outlet 14 is inclined, the exhaust gas flowing through the inner area in the inner space of the outlet portion 3 around the outlet inner portion 4 flows out from the outlet 14 to the outside earlier. Therefore, the exhaust gas is urged toward the inner region in the internal space of the outlet portion 3, and the flow of the exhaust gas is suppressed from being deviated to the outer region. As a result, the generation of turbulence and/or peeling can be suppressed, and the airflow noise can be reduced.

(5) Further, in embodiment 5, the exhaust gas that has passed through the outlet 11 is caused to diffuse by the curled portion 16 of the edge portion of the outlet 11. Therefore, it is possible to suppress generation of a vortex flow by the exhaust gas flowing out from the outlet 11, and to reduce the airflow sound. Further, it is possible to suppress the occurrence of injury or the like due to contact with the outlet 11 of the tail pipe 1.

Therefore, noise generated by the exhaust gas can be reduced more appropriately.

(6) Further, according to embodiment 6, in the portion of the outlet portion 3 up to the outlet 11, the internal space of the outlet portion 3 is expanded toward the downstream side by the outlet inside portion 4. Therefore, the flow velocity of the exhaust gas at the outlet portion 3 can be appropriately reduced, and the airflow sound can be reduced.

Further, since the outlet outer portion 8 extends in a state where the axial distance is kept substantially constant, the inner area of the periphery of the outlet inner portion 4 is further enlarged than the outer area of the periphery of the outlet outer portion 8 in the inner space of the outlet portion 3. Therefore, the exhaust gas having passed through the bent portion 2 is urged to approach the inner region, and as a result, the flow of the exhaust gas can be suppressed from being deviated to the outer region, and the flow of the exhaust gas can be promoted to be more uniform. This can suppress the generation of turbulence and reduce the flow noise.

Further, since the axial distance of the outlet outer portion 8 is kept substantially constant, the exhaust gas flowing through the outer region can be suppressed from peeling off from the wall surface of the outlet portion, and the airflow sound can be reduced.

Therefore, noise generated by the exhaust gas can be reduced more appropriately.

[ other embodiments ]

(1) The tail pipe can be configured by the outlet portion 3 in embodiments 1 to 6. That is, the tail pipe 1 of embodiments 1 to 6 may be configured not to include the bent portion 2. By connecting this tail pipe to the downstream side of the curved section in the exhaust flow path of the vehicle, the same effect can be obtained.

(2) In embodiments 1 to 6, the outlet inner sides 4 and 6 and the outlet outer sides 5 and 7 extend linearly in an axial cross section and are inclined at a substantially constant angle with respect to the axis 31. However, the shapes of the axial cross sections of the outlet inner sides 4, 6 and the outlet outer sides 5, 7 are not limited to this. Specifically, the axial cross-sections of the outlet inner portions 4 and 6 and the outlet outer portions 5 and 7 may extend in a curved shape, for example, or may have a plurality of linear sections having different angles with respect to the axis 31. In the case of this configuration, the same effect can be obtained by making the rate of increase in the axial distance of the outlet inner portion larger than the rate of increase in the axial distance of the outlet outer portion over the entire area of the outlet inner portion and the outlet outer portion.

Further, a straight tube portion forming an exhaust gas flow path extending in a straight line may be provided at the downstream end portion of the curved portion.

(3) In the outlet portion 3 in the 1 st to 6 th embodiments, both the inside home position and the outside home position are located at the end portion of the outlet portion 3 on the inlet 30 side, and the inside home position and the outside home position are opposed to each other in the width direction of the outlet portion 3. However, the inner start position and/or the outer start position may be provided on the downstream side of the inlet 30 of the outlet portion 3. The inner start position may be located downstream of the outer start position, or conversely, the outer start position may be located downstream of the inner start position.

(4) In embodiments 1 to 6, the inner starting position and the outer starting position may be located at the bending portion 2. That is, the outlet inner portion and the outlet outer portion may be provided across the bending portion 2 and the outlet portion 3. The same effect can be obtained with the above-described configuration.

(5) A plurality of constituent elements may realize a plurality of functions of one constituent element in the above-described embodiments, or a plurality of constituent elements may realize one function of one constituent element. Further, a plurality of functions included in a plurality of constituent elements may be realized by one constituent element, or one function realized by a plurality of constituent elements may be realized by one constituent element. In addition, a part of the configuration of the above embodiment may be omitted. At least a part of the structure of the above embodiment may be added to the structure of the above other embodiment, or at least a part of the structure of the above embodiment may be replaced with the structure of the above other embodiment.