JP7061221B1 - Exhaust pipes for automobiles and mufflers for automobiles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust pipe and an automobile muffler capable of obtaining high sound deadening performance with a relatively simple structure. An exhaust pipe 100 or an automobile muffler 1 of the present invention includes a concave portion 121 formed in a concave shape on an outer peripheral surface of an outlet end portion 110 from which exhaust gas is discharged. [Selection diagram] FIG. 2A

Description

The present invention relates to an exhaust pipe that discharges exhaust gas to the outside air, and an automobile muffler provided with the exhaust pipe.

Patent Document 1 discloses a structure of a tail pipe in which an annular device is mounted near the outlet of the tail pipe as an exhaust pipe for discharging exhaust gas to the outside air to reduce airflow noise. This tail pipe is complicated in structure because an annular device is attached to the tail pipe.

Japanese Unexamined Patent Publication No. 2004-360618

The present invention provides an exhaust pipe and a muffler for an automobile, which have a relatively simple structure and can obtain high sound deadening performance.

According to an aspect of the present invention, the exhaust pipe for an automobile has a concave portion formed in a concave shape inward in the radial direction from the outer peripheral surface of the outlet end portion from which the exhaust gas is discharged , and an inner peripheral portion of the outlet end portion. The concave portion and the convex portion are integrally formed on the front and back sides of the outlet end portion, and the concave portion and the convex portion are integrally formed on the front and back sides of the outlet end portion. A plurality of recesses are provided in the portion in the circumferential direction, and the recesses are formed in a V-groove shape in which the depth gradually increases toward the exhaust direction of the exhaust gas discharged from the inside of the exhaust pipe for automobiles through the outlet end portion. The convex portion is formed in a V-shape whose width is gradually increased and a tapered shape whose height is gradually increased along the discharge direction of the exhaust gas discharged from the exhaust pipe for an automobile through the outlet end portion. The height X protruding inward in the radial direction from the inner wall surface of the convex portion and the inner diameter Y of the outlet end portion satisfy the relational expression of 0 <X / Y ≦ 0.1 and flow along the inner wall surface. By increasing the flow velocity of the exhaust gas at the convex portion and guiding the flow of the exhaust gas along the inner wall surface at the outlet end portion along the convex portion, the exhaust gas is discharged from the outlet end portion. At the same time as promoting the collapse of the vortex ring formed by the friction between the exhaust gas and the outside air, the speed difference between the exhaust gas discharged from the exhaust gas for automobiles and the outside air introduced along the recess is the outlet end portion. By relaxing in the vicinity, the generation of the vortex ring is suppressed .

According to the above embodiment, the concave recess formed on the outer peripheral surface of the outlet end of the exhaust pipe efficiently suppresses the generation of a vortex ring when the exhaust gas is discharged from the outlet end of the exhaust pipe. And high muffling performance can be obtained.

FIG. 1 is a schematic perspective view of an automobile muffler to which an exhaust pipe according to the first embodiment of the present invention is applied. FIG. 2A is a schematic perspective view showing the outlet end of the exhaust pipe. FIG. 2B is a front view in FIG. 2A. FIG. 2C is an enlarged view of the IIC portion in FIG. 2B. FIG. 3A is an enlarged perspective view of the vicinity of the convex portion. FIG. 3B is a cross-sectional view taken along the line IIIB-IIIB in FIG. 2B. FIG. 4A is a cross-sectional view illustrating the flow of exhaust gas at the outlet end of the exhaust pipe. FIG. 4B is a perspective view illustrating the flow of exhaust gas at the outlet end of the exhaust pipe. FIG. 5 is a diagram showing a state of a vortex ring of exhaust gas discharged from an exhaust pipe according to a comparative example. FIG. 6 is a diagram showing a state of vortex ring collapse (vortex ring suppression) of exhaust gas discharged from the exhaust pipe according to the first embodiment of the present invention. FIG. 7A is a diagram showing the results of a comparative experiment of sound deadening performance between the exhaust pipe according to the comparative example shown in FIG. 5 and the exhaust pipe according to the first embodiment of the present invention. FIG. 7B is a diagram showing the results of a comparative experiment of sound deadening performance between the exhaust pipe according to the comparative example shown in FIG. 5 and the exhaust pipe according to the first embodiment of the present invention. FIG. 8 is a diagram illustrating the sound deadening effect sensitivity depending on the ratio of the height of the convex portion to the inner diameter of the outlet end portion. FIG. 9 is a diagram illustrating the sound deadening effect sensitivity depending on the angle of the V-shape in the recess. FIG. 10 is a side view of the exhaust pipe according to the first modification of the first embodiment of the present invention. FIG. 11A is a side view of the exhaust pipe according to the second modification of the first embodiment of the present invention. 11B is a front view of FIG. 11A. FIG. 12 is a plan view of the exhaust pipe according to the third modification of the first embodiment of the present invention. FIG. 13 is a cross-sectional view of a plane of an automobile muffler to which an exhaust pipe according to a fourth modification of the first embodiment of the present invention is applied. FIG. 14 is a side view of the exhaust pipe according to the second embodiment of the present invention. FIG. 15A is a cross-sectional view of the side surface in FIG. FIG. 15B is a cross-sectional view of a side surface of an exhaust pipe according to a modified example of the second embodiment of the present invention. FIG. 16 is a plan view of the exhaust pipe according to the third embodiment of the present invention. FIG. 17 is a cross-sectional view of the side surface in FIG.

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

(First Embodiment)
Hereinafter, the exhaust pipe 100 according to the first embodiment of the present invention and the automobile muffler 1 provided with the exhaust pipe 100 will be described with reference to FIGS. 1 to 13.

First, the configurations of the automobile muffler 1 and the exhaust pipe 100 will be described with reference to FIGS. 1 to 3B.

FIG. 1 is a schematic perspective view of an automobile muffler 1 to which the exhaust pipe 100 is applied. FIG. 2A is a schematic perspective view showing the outlet end 110 of the exhaust pipe 100. FIG. 2B is a front view in FIG. 2A. FIG. 2C is an enlarged view of the IIC portion in FIG. 2B. FIG. 3A is an enlarged perspective view of the vicinity of the convex portion 120. FIG. 3B is a cross-sectional view taken along the line IIIB-IIIB in FIG. 2B.

As shown in FIG. 1, the automobile muffler 1 includes a muffler main body 10 and an exhaust pipe 100.

The exhaust pipe 100 is formed in a cylindrical shape. The exhaust pipe 100 has an outlet end 110. Although not shown, the exhaust pipe 100 purifies the exhaust gas discharged from the internal combustion engine (engine) with a catalyst and then discharges the exhaust gas from the outlet end 110 of the tail tube to the outside air.

As shown in FIG. 2A, the outlet end 110 is cut in a plane perpendicular to the center line of the cylindrical exhaust pipe 100 to form a substantially circular shape.

A convex portion 120 that projects radially inward (inner peripheral side) from the inner wall surface 111 is provided on the inner peripheral portion of the outlet end portion 110. A plurality of convex portions 120 are provided along the circumferential direction of the outlet end portion 110.

The outer peripheral portion of the outlet end 110 is provided with a concave portion 121 formed in a concave shape from the outer peripheral surface toward the inner side (inner peripheral side) in the radial direction. A plurality of recesses 121 are provided along the circumferential direction of the outlet end 110.

The convex portion 120 and the concave portion 121 are provided at the same position in the circumferential direction at the outlet end portion 110 of the exhaust pipe 100. That is, the convex portion 120 and the concave portion 121 are provided integrally on the front and back sides at the outlet end portion 110 of the exhaust pipe 100. The protrusions 120 and 121 are provided at equal intervals in the circumferential direction at the outlet end 110 of the exhaust pipe 100. The convex portion 120 and the concave portion 121 are formed by press working on the outlet end portion 110 of the exhaust pipe 100.

In the exhaust pipe 100, the flow of exhaust gas discharged from the inside of the exhaust pipe 100 is controlled by a plurality of convex portions 120 and concave portions 121 provided at the outlet end portion 110. As a result, in addition to suppressing the vortex ring formed when the exhaust gas is discharged from the outlet end 110 of the exhaust pipe 100, a collapse effect can be obtained, so that high sound deadening performance can be obtained.

Next, the operation of the exhaust pipe 100 will be described with reference to FIGS. 4A and 4B.

FIG. 4A is a cross-sectional view illustrating the flow of exhaust gas at the outlet end 110 of the exhaust pipe 100. FIG. 4B is a perspective view illustrating the flow of exhaust gas at the outlet end 110 of the exhaust pipe 100.

As shown in FIGS. 4A and 4B, in the exhaust pipe 100, the flow of exhaust gas passing through the inner wall surface 111 side of the exhaust pipe 100 becomes faster due to the influence of one convex portion 120 or the adjacent convex portions 120. As a result, a vortex ring is generated by the speed difference that the main flow of the exhaust gas discharged from the exhaust pipe 100 (arrow F1 in FIG. 4A) receives at the outlet end 110 of the exhaust pipe 100, and the exhaust gas starts from the plurality of convex portions 120. The vortex ring can be destroyed by the action of increasing the flow of gas (vortex ring collapse effect). In particular, in the exhaust pipe 100, the vortex ring collapse effect can be enhanced by providing a plurality of the above-mentioned convex portions 120 in the circumferential direction of the outlet end portion 110.

Further, in the exhaust pipe 100, a negative pressure is applied to the exhaust gas (mainstream) discharged from the exhaust pipe 100 in the vicinity of the downstream end portion of the convex portion 120 on the concave portion 121 side provided integrally with the convex portion 120 on the front and back sides. Occur. As a result, outside air is introduced along the recess 121. As a result, the speed difference between the main flow of the exhaust gas discharged from the exhaust pipe 100 (arrow F1 in FIG. 4A) and the outside air introduced from the recess 121 (arrow F2 in FIG. 4A) is the outlet end 110 of the exhaust pipe 100. It is relaxed in the vicinity, and the generation of the vortex ring in the space S1 (see FIG. 4A) can be effectively suppressed by the speed difference (vortex ring suppression effect).

That is, in the present embodiment, by providing the plurality of convex portions 120 and the concave portions 121 at the outlet end 110 of the exhaust pipe 100, the synergistic effect of the vortex ring collapse effect and the vortex ring suppression effect described above can be obtained, and high sound deadening can be obtained. Performance can be obtained.

In addition, instead of providing both the plurality of convex portions 120 and the concave portions 121 at the outlet end portion 110, only the plurality of convex portions 120 or only the plurality of concave portions 121 may be provided. When only a plurality of convex portions 120 are provided without providing the concave portions 121 at the outlet end portion 110, the vortex ring collapse effect can be enhanced, so that high sound deadening performance can be obtained. On the other hand, when only a plurality of concave portions 121 are provided without providing the convex portion 120 at the outlet end portion 110, the generation of the vortex ring can be effectively suppressed, so that high sound deadening performance can be obtained.

Further, the convex portion 120 and the concave portion 121 may be provided at different positions in the circumferential direction instead of being provided at the same position in the circumferential direction at the outlet end portion 110 of the exhaust pipe 100. Also in this case, the synergistic effect of the vortex ring collapse effect and the vortex ring suppression effect described above can be obtained, and high sound deadening performance can be obtained.

Further, the convex portion 120 and the concave portion 121 may be provided not over the entire circumference of the outlet end portion 110 but only at a part of the circumference.

Next, with reference to FIGS. 5 and 6, the state of the vortex ring of the exhaust gas discharged from the exhaust pipe (standard exhaust pipe) according to the comparative example and the exhaust discharged from the exhaust pipe 100 of the present embodiment. The state of gas vortex ring collapse (vortex ring suppression) will be described. FIG. 5 is a diagram showing a state of a vortex ring of exhaust gas discharged from an exhaust pipe according to a comparative example. Specifically, FIG. 5 shows a state in which exhaust gas is discharged from a cylindrical exhaust pipe (normal type) in which the convex portion 120 and the concave portion 121 are not provided in the present embodiment. FIG. 6 is a diagram showing a state of vortex ring collapse (vortex ring suppression) of exhaust gas discharged from the exhaust pipe 100 according to the present embodiment.

As shown in FIG. 5, in the normal type exhaust pipe, it can be seen that the vortex rings are generated so as to be continuous from the vicinity of the outlet. On the other hand, as shown in FIG. 6, in the exhaust pipe 100, it can be seen that the vortex ring collapses or is suppressed in the vicinity of the outlet. As described above, the effect of collapsing the vortex ring by the convex portion 120 and the effect of suppressing the vortex ring by the concave portion 121 can be obtained, so that high sound deadening performance can be obtained.

Next, with reference to FIGS. 7A and 7B, the results of a comparison experiment of sound deadening performance between the normal type exhaust pipe and the exhaust pipe 100 according to the comparative example will be described.

7A and 7B are diagrams showing the results of a comparative experiment of muffling performance between the normal type exhaust pipe and the exhaust pipe 100 according to the comparative example.

As shown in FIG. 7A, in the case of a straight tube which is an exhaust pipe formed in a straight line, the exhaust pipe 100 has a difference of 2.3 dB in the muffling effect as compared with the exhaust pipe (BASE) according to the comparative example. Was generated, and it was found that high sound deadening performance was exhibited. Further, in the case of an exhaust pipe bent in a curved shape (see FIG. 1), the exhaust pipe 100 has a difference of 0.8 dB in the muffling effect as compared with the exhaust pipe (BASE) according to the comparative example, and has a high muffling effect. It turned out to be effective.

Further, with the tightening of the noise regulation outside the vehicle, it is required to reduce the noise of the vehicle such as tire noise, engine noise, intake noise, and exhaust noise. The main cause of outside noise in exhaust noise is airflow noise. The main sound source frequency of the airflow noise of this exhaust is, for example, a frequency of about 1 kHz to 2 kHz in the muffler, but in addition to this, noise is generated in the wake of the tail tube.

On the other hand, as shown in FIG. 7B, at a frequency of about 1 kHz to 2 kHz, the exhaust pipe 100 has a large difference in muffling effect as compared with the exhaust pipe (normal tail) according to the comparative example. It was found that it exhibits high sound deadening performance.

Subsequently, the sound deadening effect sensitivity due to the shapes of the convex portion 120 and the concave portion 121 will be described mainly with reference to FIGS. 8 and 9.

First, the sound deadening effect sensitivity based on the ratio of the height X of the convex portion 120 to the inner diameter Y of the outlet end portion 110 will be described mainly with reference to FIG.

FIG. 8 is a diagram illustrating the sound deadening effect sensitivity depending on the ratio of the height X of the convex portion 120 to the inner diameter Y of the outlet end portion 110. In FIG. 8, the horizontal axis is the ratio [%] of the height X of the convex portion 120 to the inner diameter Y of the outlet end portion 110, and the vertical axis is the muffling effect sensitivity [dB (A)].

Here, the inner diameter of the outlet end 110 of the exhaust pipe 100 is Y (see FIG. 2B), and the height of the convex portion 120 protruding inward (inward in the radial direction) of the outlet end 110 of the exhaust pipe 100 is X. (See FIG. 2C). The height X is the maximum height dimension of the convex portion 120 from the inner wall surface 111 of the exhaust pipe 100.

As shown in FIG. 8, when the height X with respect to the inner diameter Y is 10 [%] or less, the muffling effect sensitivity is lower than 0.0 [dB (A)], that is, the muffling effect is large. You can see that it is. Therefore, it is desirable that the relationship between the inner diameter Y of the outlet end 110 of the exhaust pipe 100 and the height X of the convex portion 120 satisfies the relational expression of 0 <X / Y ≦ 0.1.

As described above, the relationship between the height X of the convex portion 120 and the inner diameter Y of the outlet end portion 110 of the exhaust pipe 100 satisfies the relational expression of 0 <X / Y ≦ 0.1, so that the exhaust pipe 100 The collapse effect of the vortex ring formed when the exhaust gas is discharged from the outlet end 110 can be enhanced, and high sound deadening performance can be obtained.

The height X of the convex portion 120 indicates a dimension protruding inward from the inner wall surface 111 of the outlet end portion 110 of the exhaust pipe 100, for example, from the inner wall surface 111 of the outlet end portion 110 of the exhaust pipe 100. It includes the maximum height of the convex portion 120 protruding inward in the radial direction. The inner diameter Y of the outlet end 110 of the exhaust pipe 100 is, for example, the diameter of the exhaust pipe 100 if it has a cylindrical shape, and the minor diameter of the exhaust pipe 100 if it has an elliptical cylinder shape. That is.

Next, the sound deadening effect sensitivity due to the V-shaped angle θ in the recess 121 will be described mainly with reference to FIG. 9.

FIG. 9 is a diagram illustrating the sound deadening effect sensitivity due to the V-shaped angle θ in the recess 121. In FIG. 9, the horizontal axis is the V-shaped angle θ [°] in the recess 121, and the vertical axis is the muffling effect sensitivity [dB (A)].

Here, the angle of the recess 121 in the circumferential direction of the exhaust pipe 100 is θ (see FIG. 3A), and the angle of the recess 121 in the radial direction (depth direction) of the exhaust pipe 100 is α (see FIG. 3B).

As shown in FIG. 9, when the angle θ is 60 [°] or less, the muffling effect sensitivity is lower than 0.0 [dB (A)], that is, the muffling effect is large. I understand. If the V-shaped angle θ is larger than 60 [°], the outside air cannot be sufficiently introduced into the mainstream of the exhaust gas, and the vortex ring suppressing effect may not be sufficiently obtained. Therefore, in order to obtain the desired vortex ring collapse effect, it is desirable that the V-shaped angle θ in the recess 121 satisfies the range of θ ≦ 60 °. In this case, the exhaust pipe 100 having a pipe diameter (diameter) of 63.5 [mm] (inner diameter 63.5Φ) or more is also targeted.

The recess 121 has a substantially V-shape (V-groove) even in the depth direction. Further, it is desirable that the angle α of the recess 121 in the depth direction is in the range of 5 [°] or more.

Next, with reference to FIGS. 10 to 13, the exhaust pipe 100 according to the first to fourth modifications of the first embodiment of the present invention will be described.

FIG. 10 is a side view of the exhaust pipe 100 according to the first modification of the first embodiment of the present invention. FIG. 11A is a side view of the exhaust pipe 100 according to the second modification of the first embodiment of the present invention. 11B is a front view of FIG. 11A. FIG. 12 is a plan view of the exhaust pipe 100 according to the third modification of the first embodiment of the present invention. FIG. 13 is a cross-sectional view of a plane of an automobile muffler 1 to which the exhaust pipe 100 according to the fourth modification of the first embodiment of the present invention is applied.

As shown in FIG. 10, the exhaust pipe 100 according to the first modification is formed in a cylindrical shape. The exhaust pipe 100 has an outlet end 110.

The outlet end 110 is cut by a plane that diagonally intersects the plane perpendicular to the center line of the cylindrical exhaust pipe 100 to form an oval shape (substantially elliptical shape). The outlet end 110 is provided with a convex portion 120 and a concave portion 121.

In this way, even when the outlet end 110 is cut diagonally, the above-mentioned vortex ring collapse effect and vortex ring suppression are similarly provided by providing the outlet end 110 with a plurality of convex portions 120 and concave portions 121, respectively. A synergistic effect of the effect can be obtained, and high sound deadening performance can be obtained.

As shown in FIG. 11A, the exhaust pipe 100 according to the second modification is formed in a cylindrical shape curved downward. The exhaust pipe 100 has an outlet end 110.

The outlet end 110 is opened diagonally downward because the exhaust pipe 100 is curved downward. The outlet end 110 is cut by a plane that diagonally intersects the plane perpendicular to the center line of the cylindrical exhaust pipe 100 to form an oval shape (substantially elliptical shape). The outlet end 110 is provided with a convex portion 120 and a concave portion 121.

In this way, even when the exhaust pipe 100 is formed in a cylindrical shape bent downward in a curved shape, similarly, a plurality of convex portions 120 and concave portions 121 are provided at the outlet end portion 110, respectively. The synergistic effect of the vortex ring collapse effect and the vortex ring suppression effect described above can be obtained, and high sound deadening performance can be obtained.

As shown in FIG. 12, the exhaust pipe 100 according to the third modification is formed in a cylindrical shape curved in a lateral direction. The exhaust pipe 100 has an outlet end 110.

The outlet end 110 is opened diagonally to the side because the exhaust pipe 100 is curved toward the side. The outlet end 110 is cut by a plane that diagonally intersects the plane perpendicular to the center line of the cylindrical exhaust pipe 100 to form an oval shape (substantially elliptical shape). The outlet end 110 is provided with a convex portion 120 and a concave portion 121.

In this way, even when the exhaust pipe 100 is formed in a cylindrical shape bent in a curved shape to the side, similarly, a plurality of convex portions 120 and concave portions 121 are provided at the outlet end 110, as described above. A synergistic effect of the vortex ring collapse effect and the vortex ring suppression effect can be obtained, and high sound deadening performance can be obtained.

As shown in FIG. 13, the automobile muffler 1 according to the fourth modification includes a muffler main body 10 and an exhaust pipe 100.

The muffler main body 10 includes an internal exhaust pipe 11 as a first internal exhaust pipe, an internal exhaust pipe 12 as a second internal exhaust pipe, an internal exhaust pipe 13 as a third internal exhaust pipe, and a fourth internal exhaust pipe. It has an internal exhaust pipe 14 and.

Exhaust gas discharged from the engine and passing through the catalyst is guided to the internal exhaust pipe 11. The exhaust gas discharged from the internal exhaust pipe 11 is branched into an internal exhaust pipe 12 and an internal exhaust pipe 13 and guided to each. Exhaust gas discharged from the internal exhaust pipe 12 and the internal exhaust pipe 13 merges and is guided to the internal exhaust pipe 14. The exhaust gas flowing into the internal exhaust pipe 14 is discharged to the outside through the exhaust pipe 100.

At this time, a plurality of convex portions 120 and concave portions 121 are respectively provided at the outlet end portion 11a of the internal exhaust pipe 11, the outlet end portion 12a of the internal exhaust pipe 12, and the outlet end portion 13a of the internal exhaust pipe 13. It will be provided. In addition, instead of providing a plurality of convex portions 120 and concave portions 121 in all of the outlet end portion 11a, the outlet end portion 12a, and the outlet end portion 13a, a plurality of convex portions 120 and concave portions 121 are provided in at least one of them. Should be provided.

In this way, by providing a plurality of convex portions 120 and concave portions 121 at least one of the outlet end portions 11a to 13a of the internal exhaust pipes 11 to 13 of the muffler main body 10, the above-mentioned is described inside the muffler main body 10. A synergistic effect of the vortex ring collapse effect and the vortex ring suppression effect can be obtained, and high sound deadening performance can be obtained.

According to the above first embodiment, it has the following effects.

With the tightening of vehicle noise regulations, it is required to reduce vehicle noise such as tire noise, engine noise, intake noise, and exhaust noise. The main cause of outside noise in exhaust noise is airflow noise. The main sound source frequency of the airflow noise of this exhaust is, for example, a frequency of about 1 kHz to 2 kHz in the muffler, but in addition to this, noise is generated in the wake of the tail tube.

On the other hand, the exhaust pipe 100 effectively reduces the noise generated in the wake of the tail tube. That is, the exhaust pipe 100 focuses on the vortex ring generated by the friction between the exhaust gas and the outside air with respect to the sound source generated in the space wake of the tail tube, and suppresses the generation of the vortex ring or collapses the vortex ring to cause the exhaust. It silences the sound of airflow.

In the exhaust pipe 100, a V-shaped recess (a convex portion 120 protruding inward of the outlet end 110 of the exhaust pipe 100) is provided at the rear end of the tail tube (the outlet end 110 of the exhaust pipe 100), and the tail is provided. Due to the effect of collapsing the vortex ring generated in the wake of the tube (vortex ring collapse effect), the above-mentioned exhaust airflow sound can be effectively muted.

Since the airflow noise increases in proportion to the flow velocity, it is possible to increase the tail tube diameter and reduce the flow velocity to reduce the airflow noise. On the other hand, if the diameter of the tail tube is increased, the order sound (component) that affects the muffled sound in the vehicle interior is deteriorated. Therefore, there is a limit to increasing the tail tube diameter.

Here, "the convex portions 120 protruding inward of the outlet end 110 of the exhaust pipe 100 are provided at a plurality of locations in the circumferential direction of the outlet end 110" means that the exhaust pipe 100 is provided with a plurality of locations in the circumferential direction. In addition to the configuration in which the convex portion 120 is extended so that the outlet end portion 110 and the downstream end portion of the convex portion 120 are at the same position, for example, a part of the cylindrical outlet end portion 110 of the exhaust pipe 100 is used. A configuration is also included in which the convex portion 120 is provided at the remaining position, that is, at a position in front of the exhaust gas flow direction from the outlet end portion 110. Also in this configuration, the relationship between the height X of the convex portion 120 (height X protruding radially from the inner wall surface 111 of the exhaust pipe 100) and the inner diameter Y of the outlet end portion 110 of the exhaust pipe 100 is 0 <X. By satisfying the relational expression of / Y ≦ 0.1, a desired vortex ring collapse effect can be obtained. Here, the relationship between the height X of the convex portion 120 and the inner diameter Y of the outlet end portion 110 of the exhaust pipe 100 should further satisfy the relationship of 0.03 ≦ X / Y ≦ 0.09. desirable. As a result, an optimum vortex ring collapse effect can be obtained in consideration of the inner diameter of the exhaust pipe 100.

However, as shown in FIGS. 2A to 4B, the structure is extended so that each convex portion 120 reaches the outlet end portion 110 of the exhaust pipe 100, and the outer peripheral surface side of the outlet end portion 110 of the exhaust pipe 100. By forming the concave portion 121 integrally on the front and back sides of the convex portion 120, an annular exhaust gas vortex (vortex ring) is formed from the concave portion 121 when the exhaust gas is discharged from the outlet end portion 110 of the exhaust pipe 100. It can be effectively reduced by introduction. That is, high sound deadening performance can be obtained by the synergistic effect of the vortex ring collapse effect of the convex portion 120 and the vortex ring formation suppressing effect of the introduction of outside air from the concave portion 121.

Further, the convex portion 120 has a V-shape in which the width of the convex portion 120 gradually increases along the discharge direction (arrow F1 in FIG. 4A) of the exhaust gas discharged from the inside of the exhaust pipe 100 through the outlet end portion 110. It is desirable to have. Specifically, as shown in FIG. 4B, the flow velocity of the exhaust gas flowing on the inner wall surface 111 side of the exhaust pipe 100 is increased by the substantially V-shaped convex portion 120, and at the outlet end portion 110 of the exhaust pipe 100. By guiding the flow of the exhaust gas on the inner wall surface 111 side along the V-shape, it is possible to promote the collapse of the vortex ring formed when the exhaust gas is discharged from the outlet end 110 of the exhaust pipe 100.

Further, the convex portion 120 has a tapered shape in which the height of the convex portion 120 gradually increases in the discharge direction of the exhaust gas discharged from the inside of the exhaust pipe 100 through the outlet end portion 110. The height X of the convex portion 120 in this case is the maximum height portion of the convex portion 120. Thereby, the flow of the exhaust gas discharged along the convex portion 120 near the outlet end portion 110 of the exhaust pipe 100 can be controlled by the tapered shape of the convex portion 120, and the vortex ring collapse effect can be enhanced. Further, the convex portion 120 has a tapered shape whose width gradually decreases even in the height direction thereof. Thereby, the vortex ring collapse effect can be promoted.

Further, it is desirable that a recess 121 is provided on the outer peripheral portion of the outlet end portion 110 of the exhaust pipe 100. Here, the convex portion 120 and the concave portion 121 are provided at the same position at the outlet end portion 110 of the exhaust pipe 100 (both sides are integrated at the outlet end portion 110 of the exhaust pipe 100) as described in each of the above-described embodiments. It does not have to be. For example, the positions of the convex portion 120 and the concave portion 121 may be displaced in the circumferential direction along the outer peripheral portion of the outlet end portion 110 of the exhaust pipe 100. Specifically, even if the concave portion 121 is provided on the outer peripheral surface side of the outlet end portion 110 of the exhaust pipe 100 corresponding to the adjacent convex portions 120, the outside air introduction effect and the vortex ring collapse effect can be obtained. The recess 121 may not be provided on the outer periphery of the outlet end 110 of the exhaust pipe 100. In this case, the muffling performance can be ensured by the vortex ring collapse effect of the convex portion 120. However, in order to obtain a higher muffling effect, it is desirable to provide the convex portion 120 and the concave portion 121 at the outlet end portion 110 of the exhaust pipe 100. From the viewpoint of processing, it is preferable to integrate the convex portion 120 and the concave portion 121 on the front and back sides.

Further, it is desirable that the recess 121 has a V-shape whose width gradually increases toward the downstream side in the longitudinal direction of the exhaust pipe 100. As a result, the introduction of outside air is promoted, and the effect of suppressing the vortex ring can be enhanced.

Further, in order to obtain a desired vortex ring collapse effect, it is desirable that the V-shaped angle θ in the recess 121 satisfies the range of θ ≦ 60 °. In this case, a pipe diameter having an inner diameter of 63.5Φ or more of the exhaust pipe 100 can also be targeted. If the V-shaped angle θ is larger than 60 °, the outside air cannot be sufficiently introduced into the mainstream of the exhaust gas, and the vortex ring suppressing effect may not be sufficiently obtained.

It is desirable that the recess 121 has a substantially V-shape (V-groove) even in the depth direction. It is desirable that the angle α (see FIG. 3B) of the recess 121 in the depth direction is in the range of 5 [°] or more.

Further, the convex portion 120 or the concave portion 121 is formed by press working on the outlet end portion 110 of the exhaust pipe 100, for example. As a result, it becomes possible to integrally provide the exhaust pipe 100, so that in the present embodiment, a high sound deadening effect can be obtained while the configuration is relatively simple.

Further, it is desirable that the recess 121 has a shape (V-groove shape) in which the depth of the exhaust pipe 100 gradually increases in the longitudinal direction. As a result, the effect of introducing outside air can be further enhanced, and the formation of a vortex ring can be effectively suppressed. As a result, a vortex ring collapse effect due to the air flow formed by the convex portion 120 is added, and high sound deadening performance can be obtained.

In the present embodiment, the relationship between the height X of the convex portion 120 (height X protruding radially from the inner wall surface 111 of the exhaust pipe 100) and the inner diameter Y of the outlet end portion 110 of the exhaust pipe 100 is 0. By satisfying the relational expression <X / Y ≦ 0.1, a desired vortex ring collapse effect can be obtained. However, the relational expression between the height X of the convex portion 120 and the inner diameter Y of the outlet end 110 of the exhaust pipe 100 is not limited, and for example, it projects inward of the outlet end 110 of the exhaust pipe 100. A structure in which the convex portions 120 are provided at a plurality of locations in the circumferential direction of the outlet end portion 110 and the plurality of concave portions 121 are provided on the outer peripheral portion of the outlet end portion 110 of the exhaust pipe 100 can also be widely targeted. In this case, the convex portion 120 and the concave portion 121 may be integrated on the front and back sides, or may be provided at different positions on the front and back sides. In any case, the vortex ring collapse effect of the convex portion 120 and the vortex ring suppression effect of the concave portion 121 can be synergistically obtained, and high sound deadening performance can be obtained.

(Second Embodiment)
Hereinafter, the exhaust pipe 200 according to the second embodiment of the present invention will be described with reference to FIGS. 14 to 15B. In each of the following embodiments, the differences from the first embodiment will be mainly described, and the same reference numerals are given to the configurations having the same functions, and the description thereof will be omitted.

FIG. 14 is a side view of the exhaust pipe 200. FIG. 15A is a cross-sectional view of the side surface in FIG. FIG. 15B is a cross-sectional view of the side surface of the exhaust pipe 200 according to the modified example of the second embodiment of the present invention.

As shown in FIG. 14, the exhaust pipe 200 has an exhaust pipe main body 210 and a finisher 220.

As shown in FIG. 15A, the exhaust pipe main body 210 is formed in a cylindrical shape. The exhaust pipe main body 210 has an outlet end portion 210a.

The outlet end portion 210a is cut by a plane that diagonally intersects the plane perpendicular to the center line of the cylindrical exhaust pipe 200 to form an oval shape (substantially elliptical shape). The outlet end portion 210a is provided with a convex portion 120 and a concave portion 121.

The finisher 220 has a cylindrical portion 221 and a bottom portion 222.

The cylindrical portion 221 is formed in a cylindrical shape having an inner diameter larger than the outer diameter of the exhaust pipe main body 210. The cylindrical portion 221 is provided on the outer periphery of the exhaust pipe main body 210 in a substantially concentric shape with a gap. The cylindrical portion 221 forms an annular space 223 with the exhaust pipe main body 210. The cylindrical portion 221 has an outlet end portion 221a on the downstream side in the exhaust gas flow direction.

The outlet end portion 221a is cut by a plane that diagonally intersects the plane perpendicular to the center line of the cylindrical exhaust pipe 200 to form an oval shape (substantially elliptical shape). The outlet end portion 221a is substantially parallel to the outlet end portion 210a of the exhaust pipe main body 210. The outlet end portion 221a is provided with a convex portion 120 and a concave portion 121.

The bottom portion 222 is provided at the upstream end portion 221b on the upstream side in the exhaust gas flow direction of the cylindrical portion 221. The bottom portion 222 connects the outer peripheral surface of the exhaust pipe main body 210 and the inner peripheral surface of the cylindrical portion 221, and holds the finisher 220 with respect to the exhaust pipe main body 210. The bottom 222 has a plurality of through holes 224 that allow the space 223 to communicate with the outside.

In the exhaust pipe 200, the exhaust gas is discharged from the outlet end portion 210a of the exhaust pipe main body 210, and the outside air is guided to the space 223 through the through hole 224 of the finisher 220 and discharged from the outlet end portion 221a. Therefore, the flow velocity difference between the exhaust gas discharged from the outlet end 210a and the outside air discharged from the outlet end 221a is smaller than the flow velocity difference between the exhaust gas and the outside air when the finisher 220 is not provided. .. Therefore, the frictional force between the exhaust gas that generates the vortex ring and the outside air becomes small.

Further, since the convex portion 120 and the concave portion 121 are provided at the outlet end portion 210a of the exhaust pipe main body 210 and the outlet end portion 221a of the finisher 220, the synergistic effect of the vortex ring collapse effect and the vortex ring suppression effect described above can be obtained. High muffling performance can be obtained.

In the modified example shown in FIG. 15B, a plurality of through holes 211 communicating with the space 223 are provided on the outer periphery of the exhaust pipe main body 210. Further, the finisher 220 does not have a through hole 224 in the bottom 222.

In this modification, the exhaust gas is discharged from the outlet end 210a of the exhaust pipe main body 210, and a part of the exhaust gas is guided to the space 223 through the through hole 211 of the exhaust pipe main body 210 to the outlet end 221a. Is discharged from. Therefore, the exhaust gas is branched into the outlet end portion 210a and the outlet end portion 221a and discharged, so that the flow velocity becomes low. Therefore, the difference in flow velocity between the exhaust gas and the outside air flowing around the finisher 220 becomes small. Therefore, the frictional force between the exhaust gas that generates the vortex ring and the outside air becomes small.

Further, since the convex portion 120 and the concave portion 121 are provided at the outlet end portion 210a of the exhaust pipe main body 210 and the outlet end portion 221a of the finisher 220, the synergistic effect of the vortex ring collapse effect and the vortex ring suppression effect described above can be obtained. High muffling performance can be obtained.

Instead of providing the convex portion 120 and the concave portion 121 on both the outlet end portion 210a of the exhaust pipe main body 210 and the outlet end portion 221a of the finisher 220, the convex portion 120 and the concave portion 121 may be provided on only one of them. ..

(Third Embodiment)
Hereinafter, the exhaust pipe 300 according to the third embodiment of the present invention will be described with reference to FIGS. 16 and 17.

FIG. 16 is a plan view of the exhaust pipe 300. FIG. 17 is a cross-sectional view of the side surface in FIG.

As shown in FIG. 16, the exhaust pipe 300 has an exhaust pipe main body 310 and a cover 320.

The exhaust pipe main body 310 is formed in a cylindrical shape that is curved toward the side. The exhaust pipe main body 310 has an outlet end portion 310a.

The outlet end portion 310a is opened diagonally laterally because the exhaust pipe main body 310 is curved toward the side. The outlet end portion 310a is cut by a plane that diagonally intersects the plane perpendicular to the center line of the cylindrical exhaust pipe main body 310 to form an oval shape (substantially elliptical shape). The outlet end portion 310a is provided with a convex portion 120 and a concave portion 121.

The cover 320 is provided in a curved surface shape having a substantially arcuate cross section at intervals above the exhaust pipe main body 310. The cover 320 forms a space 323 with the exhaust pipe main body 310. The cover 320 has an outlet end portion 321a on the downstream side in the exhaust gas flow direction. The outlet end portion 321a is provided with a convex portion 120 and a concave portion 121.

In the exhaust pipe 300, the exhaust gas is discharged from the outlet end portion 310a of the exhaust pipe main body 310, and the outside air is guided to the space 323 between the cover 320 and the exhaust pipe main body 310 and discharged from the outlet end portion 321a. .. By providing the convex portion 120 and the concave portion 121 at the outlet end portion 321a, the flow path area of the space 323 is reduced and the flow velocity of the outside air discharged from the outlet end portion 321a is increased. Therefore, the flow velocity difference between the exhaust gas discharged from the outlet end 310a and the outside air discharged from the outlet end 321a is smaller than the flow velocity difference between the exhaust gas and the outside air when the cover 320 is not provided. .. Therefore, the frictional force between the exhaust gas that generates the vortex ring and the outside air becomes small.

Further, since the convex portion 120 and the concave portion 121 are provided at the outlet end portion 310a of the exhaust pipe main body 310 and the outlet end portion 321a of the cover 320, the synergistic effect of the vortex ring collapse effect and the vortex ring suppression effect described above can be obtained. High sound deadening performance can be obtained.

Although the embodiments of the present invention have been described above, the above-described embodiments show only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above-described embodiments. not.

For example, in each of the above-described embodiments, the exhaust pipe 100, the exhaust pipe main body 210, and the exhaust pipe main body 310 are formed in a cylindrical shape having a substantially circular cross-sectional shape. Not limited to this, the exhaust pipe 100, the exhaust pipe main body 210, and the exhaust pipe main body 310 are formed, for example, into a tubular shape having an oval (oval) cross-sectional shape or a cylindrical shape having a rectangular cross-sectional shape. May be good. That is, the exhaust pipe 100, the exhaust pipe main body 210, and the exhaust pipe main body 310 may have a tubular shape having an arbitrary cross-sectional shape.

1 Automotive muffler 100 Exhaust pipe 200 Exhaust pipe 300 Exhaust pipe 110 Outlet end 111 Inner wall surface 120 Convex 121 Concave 210a Outlet end 310a Outlet end X Convex height Y Inner diameter of exhaust pipe

Claims (10)

Exhaust pipe for automobiles
A concave portion formed in a radial inward direction from the outer peripheral surface of the outlet end where the exhaust gas is discharged, and a concave portion.
A convex portion formed on the inner peripheral portion of the outlet end portion and protruding inward in the radial direction from the inner wall surface of the outlet end portion.
Equipped with
The concave portion and the convex portion are integrally provided on the front and back sides of the outlet end portion, and a plurality of the concave portions and the convex portions are provided on a part of the outlet end portion in the circumferential direction.
The recess is formed in a V-groove shape whose depth gradually increases in the discharge direction of the exhaust gas discharged from the inside of the exhaust pipe for an automobile through the outlet end portion.
The convex portion is formed in a V-shape whose width is gradually increased and a tapered shape whose height is gradually increased along the discharge direction of the exhaust gas discharged from the inside of the exhaust pipe for an automobile through the outlet end portion.
The height X protruding inward in the radial direction from the inner wall surface of the convex portion and the inner diameter Y of the outlet end portion satisfy the relational expression of 0 <X / Y ≦ 0.1.
By increasing the flow rate of the exhaust gas flowing along the inner wall surface at the convex portion and guiding the flow of the exhaust gas along the inner wall surface at the outlet end portion along the convex portion, the outlet end is guided. While promoting the collapse of the vortex ring formed by the friction between the exhaust gas and the outside air when the exhaust gas is discharged from the portion, the exhaust gas discharged from the automobile exhaust pipe and the outside air introduced along the recess are By relaxing the speed difference near the outlet end, the generation of the vortex ring is suppressed.
Exhaust pipe for automobiles characterized by that. The automobile exhaust pipe according to claim 1 .
The convex portion and the concave portion are provided at equal intervals in the circumferential direction of the outlet end portion.
Exhaust pipe for automobiles characterized by that. The automobile exhaust pipe according to claim 1 or 2 .
The height X of the convex portion is the maximum height portion in the convex portion.
Exhaust pipe for automobiles characterized by that. The automobile exhaust pipe according to any one of claims 1 to 3 .
The recess has a V-shape whose width gradually increases in the discharge direction of the exhaust gas discharged from the inside of the exhaust pipe for an automobile through the outlet end portion.
Exhaust pipe for automobiles characterized by that. The automobile exhaust pipe according to any one of claims 1 to 4 .
The V-shaped angle θ in the recess is in the range of θ ≦ 60 °.
Exhaust pipe for automobiles characterized by that. The automobile exhaust pipe according to any one of claims 1 to 5.
It is formed in a cylindrical shape that is curved toward the exit end.
Exhaust pipe for automobiles characterized by that. The automobile exhaust pipe according to any one of claims 1 to 5.
The outlet end is cut by a plane that diagonally intersects a plane perpendicular to the center line of the cylindrical exhaust pipe for an automobile to form an oval shape.
Exhaust pipe for automobiles characterized by that. The automobile exhaust pipe according to any one of claims 1 to 7.
An exhaust pipe main body in which the outlet end is formed and exhaust gas is discharged from the outlet end.
A finisher having an inner diameter larger than the outer diameter of the exhaust pipe main body, provided with an annular space between the exhaust pipe main body and the exhaust pipe main body, and having a through hole for communicating the annular space with the outside.
To prepare
Exhaust pipe for automobiles characterized by that. The automobile exhaust pipe according to any one of claims 1 to 7.
An exhaust pipe main body in which the outlet end is formed and exhaust gas is discharged from the outlet end.
A finisher having an inner diameter larger than the outer diameter of the exhaust pipe main body and provided with an annular space between the exhaust pipe main body and the finisher.
Equipped with
The exhaust pipe body has a plurality of through holes communicating with the annular space.
Exhaust pipe for automobiles characterized by that. The automobile exhaust pipe according to any one of claims 1 to 9 .
A muffler for automobiles that is characterized by that.

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