JP2019019677A - Muffler - Google Patents

Abstract

To provide a muffler capable of controlling flow of exhaust gas in a muffling chamber to reduce occurrence of airflow noise and reduce rise of back pressure.SOLUTION: A muffler 1 has an inlet pipe 10 whose downstream side end part is opened, and an outlet pipe 11, wherein in a muffling chamber 6 where a downstream side opening end part 10a of the inlet pipe 10 is positioned, a convex part 15 projecting toward the downstream side opening end part 10a is provided at a portion facing to the downstream side opening end part 10a; and a top 21 on the downstream side opening end part 10a in the convex part 15 is not provided on an axial line of a central axis X-X of the downstream side opening end part 10a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a silencer.

  Conventionally, a silencer 101 as shown in FIGS. 14 and 15 is known as a silencer used in an exhaust system of an internal combustion engine. This silencer is referred to as Prior Art 1.

  The silencer 101 divides the internal space of the casing 102 by an inner plate 103 and is partitioned into a first extension chamber 104 and a second extension chamber 105, which are two silencer chambers. The first extension chamber 104 and the second extension chamber 105 communicates with a communication hole 106 formed of a plurality of punching holes formed in the inner plate 103.

  In addition, an inlet pipe 107 into which exhaust gas discharged from the internal combustion engine is introduced is fixed to the casing 102 and the inner plate 103 so that the downstream opening end 107 a of the inlet pipe 107 opens into the first expansion chamber 104. ing. An outlet pipe 108 for discharging exhaust gas in the silencer 101 to the outside is fixed to the casing 102 and the inner plate 103, and an upstream opening end portion 108 a of the outlet pipe 108 opens into the second expansion chamber 105. .

  The exhaust gas discharged from the internal combustion engine flows through the inlet pipe 107 into the first expansion chamber 104, and then flows through the communication hole 106 of the inner plate 103 into the second expansion chamber 105 to be muffled. Later, it is discharged to the outside through the outlet pipe 108.

  In the silencer 101, exhaust gas flowing into the first expansion chamber 104 from the downstream opening end 107a of the inlet pipe 107 collides with the inner wall surface 102a facing the downstream opening end 107a in the casing 102, and Due to the shape of the part near the downstream opening end 107 a of the inlet pipe 107, the arrangement form of the communication holes 106 of the inner plate 103, the pressure drifts in a low direction.

  Accordingly, as shown in FIG. 16, the exhaust gas mainly flows downward in FIGS. 15 and 16 in the first expansion chamber 104, and swirls in the lower portion of the first expansion chamber 104 in FIG. 17. There is a problem that a flow is generated and the exhaust gas is disturbed at a portion flowing out to the second expansion chamber 105 through the communication hole 106 of the inner plate 103, thereby generating airflow noise and increasing back pressure.

  Therefore, conical protrusions are provided on the inner wall surface of the casing facing the downstream opening end of the inlet pipe so that the top is located on the axis of the central axis of the inlet pipe, thereby suppressing the generation of spiral flow. There has been proposed a silencer configured to do so (see Patent Document 1). The silencer described in Patent Document 1 is referred to as Conventional Technology 2.

  In addition, a convex portion protruding inward is formed on the inner wall surface of the casing facing the downstream opening end of the inlet pipe, and an axial core positioned on the axis of the central axis of the inlet pipe is formed at the central portion of the convex portion. There has been proposed a silencer in which a concave groove having a groove is formed to suppress the generation of a spiral flow (see Patent Document 2). The silencer described in Patent Document 2 is referred to as Prior Art 3.

Japanese Utility Model Publication No. 55-37692 Japanese Patent Publication No. 2-31209

  In the silencer of the prior art 2, the conical protrusion provided on the inner wall surface of the casing is provided so that the top thereof is collinear with the axis of the inlet pipe. The exhaust gas cannot be uniformly diffused into the expansion chamber simply by diffusing radially with the projections, and it is difficult to solve the above problems.

  Similarly to the silencer of the prior art 2, the silencer of the prior art 3 cannot uniformly diffuse the exhaust gas into the expansion chamber, and it is difficult to solve the above problems.

  Therefore, an object of the present invention is to propose a silencer that solves the above problems.

In order to solve the above-described problem, the present invention provides a silencer having an inlet pipe and an outlet pipe whose downstream end is open.
In the muffler chamber where the downstream opening end of the inlet pipe is located, a convex portion that protrudes toward the downstream opening end is provided at a portion facing the downstream opening end.
The top of the convex portion on the downstream opening end portion side is not provided on the axis of the central axis of the downstream opening end portion.

  The convex portion may have a plurality of inclined surfaces inclined with respect to the central axis of the downstream opening end portion, and the apex may be a ridge line on the inlet pipe side of the inclined surface.

  The plurality of inclined surfaces may have different areas.

  The present invention provides a projecting portion projecting toward the downstream opening end at a portion facing the downstream opening end in the silencer chamber where the downstream opening end of the inlet pipe opens, and the top of the convex portion is provided. The exhaust gas flowing from the downstream opening end of the inlet pipe into the muffler chamber hits the convex portion, so that the flow of the exhaust gas is prevented from being provided on the axis of the central axis of the downstream opening end. It is scraped and deflected, and the exhaust gas can be evenly diffused in the muffler chamber, so that airflow noise can be reduced and back pressure can be reduced.

  Further, the convex portion has a plurality of inclined surfaces inclined with respect to the central axis of the downstream opening end portion, and the apex is a ridge line on the inlet pipe side of the inclined surface, whereby the downstream opening of the inlet pipe When exhaust gas flowing into the noise reduction chamber from the edge hits the convex part, the exhaust gas flow can be reliably scraped and deflected, further reducing airflow noise and reducing back pressure. Can do.

  In addition, by making the areas of the inclined surfaces of the convex portions different, the deflection and flow velocity of the exhaust gas flow can be adjusted freely, further reducing airflow noise and reducing back pressure. can do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical partial cross-sectional view of a silencer according to Embodiment 1 of the present invention. AA sectional view taken on the line AA of FIG. The side view of the convex part used for Example 1 of this invention. The figure seen from the protrusion side of FIG. The BB sectional view which shows the flow of the exhaust gas in the silencer of FIG. The CC sectional view taken on the line which shows the flow of the exhaust gas in the silencer of FIG. The graph which shows the characteristic of the silencer of FIG. The side view of an example of the convex part used for Example 2 of this invention. The side view of the other example of the convex part used for Example 2 of this invention. The figure which showed an example of the convex part used for Example 3 of this invention, and was seen from the protrusion side. The perspective view of an example of the convex part used for Example 4 of this invention. The longitudinal cross-sectional view of the silencer which concerns on Example 5 of this invention. Sectional drawing equivalent to FIG. 2 with the silencer which concerns on Example 6 of this invention. The longitudinal cross-sectional view of the silencer of the prior art 1. FIG. The DD sectional view taken on the line of FIG. The EE sectional view taken on the line which shows the flow of the exhaust gas in the silencer of FIG. The FF sectional view taken on the line which shows the flow of the exhaust gas in the silencer of FIG.

  A mode for carrying out the present invention will be described based on an embodiment shown in the drawings.

[Example 1]
FIG. 1 shows a longitudinal sectional view of a silencer 1 according to Embodiment 1 of the present invention. As shown in FIG. 1, the silencer 1 has a casing 2 made of a plurality of outer shell members, and a space 3 is formed in the casing 2.

  In the space 3 of the casing 2, a first expansion chamber 6 and a second expansion chamber 7, which are two silencing chambers, are partitioned by an inner plate 4, and the first expansion chamber 6 and the second expansion chamber 7 are partitioned. Are communicated by a communication hole 8 formed of a plurality of punching holes formed in the inner plate 4.

  An inlet pipe 10 into which exhaust gas discharged from the internal combustion engine is introduced is inserted and fixed in insertion holes formed in the casing 2 and the inner plate 4 so that both ends of the inlet pipe 10 in the axial direction are open. The downstream opening end 10a, which is an opening on the downstream side, is opened in the first expansion chamber 6. The outlet pipe 11 for discharging the exhaust gas in the silencer 1 to the outside is formed so as to be inserted and fixed in insertion holes formed in the casing 2 and the inner plate 4 so that both ends in the axial direction are opened. The upstream opening end 11a, which is the opening on the upstream side, opens into the second expansion chamber 7.

  In the space 3, a convex portion 15 formed by bending a metal plate is fixed to the inner wall surface 2 a of the casing 2, which is a portion facing the downstream opening end portion 10 a of the inlet pipe 10, by welding or the like. Yes.

  As shown in FIGS. 3 and 4, the convex portion 15 is formed by bending a single rectangular plate made of metal. The convex portions 15 have different areas and have a planar first inclined surface 16 that is inclined with respect to the central axis XX of the downstream opening end portion 10a of the inlet pipe 10 and a planar second inclined surface. 17 has two inclined surfaces, and the vertical end surface shape of the connecting portion between the end portion on the inlet pipe 10 side of the first inclined surface 16 and the end portion on the inlet pipe 10 side of the second inclined surface 17 is formed in an arc shape. Has been. The surface area of the first inclined surface 16 is formed larger than the surface area of the second inclined surface 17, and the angle α1 of the first inclined surface 16 with respect to the mounting portion of the convex portion 15 on the inner wall surface 2a of the casing 2 is the second inclined surface. 17 is set smaller than the angle α2. Moreover, as shown in FIG. 1, the convex part 15 is provided with respect to the inner wall surface 2a so that the 1st inclined surface 16 may become the inlet pipe 10 side, and the 2nd inclined surface 17 may become the outlet pipe 11 side.

  Further, the ridgeline (intersection line) 20 where the first inclined surface 16 and the second inclined surface 17 intersect, that is, the inclination direction of the inclined surface changes, is linear as shown in FIG. The ridgeline 20 constitutes a top 21 on the downstream opening end 10a side of the inlet pipe 10 in the convex portion 15. In addition, you may form the vertical end surface shape of the connection part of the 1st inclined surface 16 and the 2nd inclined surface 17 at an acute angle instead of circular arc shape.

  The first inclined surface 16 and the second inclined surface 17 are formed so that the lengths in the ridge line direction (Y-Y direction) are substantially the same in the entire direction (Z-Z direction) orthogonal to the ridge line. ing.

  Flange 22, 22 is formed on both sides of the convex portion 15, and the flange 22 is fixed to the inner wall surface 2a of the casing 2 by welding or the like, and the convex portion 15 is fixed to the inner wall surface 2a. . Note that the flange 22 may not be provided, and the edges of the inclined surfaces 16 and 17 may be fixed to the inner wall surface 2a by welding or the like.

  As shown in FIG. 2, in the present embodiment, the top portion 21 of the convex portion 15 is downstream so that the top portion 21 is not located on the central axis XX line at the downstream opening end portion 10 a of the inlet pipe 10. It is attached to the inner wall surface 2a so as to be positioned closer to the outlet pipe 11 than the central axis XX of the side opening end portion 10a.

  With the above structure, the exhaust gas discharged from the internal combustion engine passes through the inlet pipe 10 and flows into the first expansion chamber 6 from the downstream opening end portion 10a, and then passes through the communication hole 6 of the inner plate 4 to the second. The sound is silenced by flowing into the expansion chamber 7 and then discharged to the outside through the outlet pipe 11. At this time, the exhaust gas discharged from the downstream opening end portion 10 a hits the convex portion 15.

  The convex portion 15 does not have its apex 21 positioned on the central axis XX line at the downstream opening end portion 10a of the inlet pipe 10, and its two inclined surfaces 16 and 17 have the central axis X of the downstream opening end portion 10a. Due to the inclination with respect to −X and the inclination angles of the two inclined surfaces 16 and 17 are different, the exhaust gas hitting the convex portion 15 is scraped and the flow is deflected. As a result, as shown in FIGS. 5 and 6, the upward flow on the side opposite to the outlet pipe 11, which is less in the silencer 101 of the prior art 1, increases. Further, the spiral flow generated in the above-described prior art 1 is reduced, and the position of the spiral flow is away from the communication hole 8 of the inner plate 4, so that the exhaust gas is uniformly distributed in the first expansion chamber 6. After being diffused, it flows smoothly from the first expansion chamber 6 to the second expansion chamber 7. Accordingly, as shown in the graph of FIG. 7, it can be seen that the silencer 1 of the present invention has reduced airflow noise as compared with the silencer 101 of the prior art 1.

  Further, since the two inclined surfaces 16 and 17 of the convex portion 15 are configured so that their areas are different from each other, the deflection and flow velocity of the exhaust gas flow can be freely adjusted according to the configuration of the silencer 1. It is possible to optimize the flow of exhaust gas, reduce airflow noise, and reduce back pressure.

[Example 2]
In the first embodiment, the first inclined surface 16 and the second inclined surface 17 are each formed in a planar shape. However, the first inclined surface 16 and the second inclined surface 17 are the downstream opening end portions of the inlet pipe 10. In addition to being inclined with respect to the central axis XX of 10a, the two surfaces are formed so as to be positioned closer to the mounting portion side of the convex portion 15 on the inner wall surface 2a of the casing 2 toward the outer side from the top 21. For example, as shown in FIG. 8, the first inclined surface 16 </ b> A is a curved surface that bulges in the direction of the mounting portion of the convex portion 15 on the inner wall surface 2 a of the casing 2. As shown in FIG. 9, the first inclined surface 16 </ b> B may be configured with a curved surface that bulges toward the inlet pipe 10.

  The lengths of the first inclined surfaces 16, 16 </ b> A, 16 </ b> B and the second inclined surface 17 in the ridge line direction (Y-Y direction) are substantially the same in the entire direction orthogonal to the ridge line 20 (Z-Z direction). It is formed to become.

  Since the other structure is the same as that of the first embodiment, the description thereof is omitted.

  Also in the second embodiment, the same effects as in the first embodiment are obtained.

[Example 3]
In the first and second embodiments, the first inclined surfaces 16, 16 </ b> A, 16 </ b> B and the second inclined surface 17 of the convex portion 15 have a length in the ridge line direction (YY direction) orthogonal to the ridge line 20. (Z-Z direction) Although formed so as to be substantially the same throughout, the length in the ridge line direction (Y-Y direction) gradually increases and decreases in the middle in the direction orthogonal to the ridge line 20 (Z-Z direction). The convex portion 25 may be formed so as to change.

  For example, as shown in FIG. 10, the length of the first inclined surfaces 16, 16 </ b> A, 16 </ b> B of the convex portion 15 and the length of the second inclined surface 17 in the ridge line direction (Y-Y direction) is as shown in FIG. 10. The convex portion 25 may be configured by gradually narrowing at a constant rate toward the other side (downward in FIG. 10).

  Since other structures are the same as those of the first and second embodiments, description thereof is omitted.

  In the third embodiment, the same effects as in the first and second embodiments are obtained.

[Example 4]
In the said Examples 1-3, although the ridgeline 20 of the convex parts 15 and 25 was formed in linear form, you may comprise with the curve of two-dimensional or three-dimensional arbitrary shapes. For example, as shown in FIG. 11, the intermediate portion in the ridge line direction (Y-Y direction) may be a convex portion 35 that is a ridge line 30 that is recessed toward the mounting portion side of the convex portion 35 with respect to the casing 2.

  Since other structures are the same as those in the first to third embodiments, description thereof is omitted.

  In the fourth embodiment, the same effects as in the first to third embodiments are obtained.

[Example 5]
In the first to fourth embodiments, the casing 2 and the convex portions 15, 25, and 35 are configured as separate members. However, as shown in FIG. 12, the casing 42 is deformed inward by pressing or the like, and the convex portion 45 may be formed integrally with the casing 42. The shape of the convex portion 45 is formed in the same manner as the convex portions 15, 25, and 35 of Examples 1 to 4 described above.

  Since other structures are the same as those in the first to fourth embodiments, description thereof is omitted.

  Also in the fifth embodiment, the same effects as in the first to fourth embodiments are obtained.

[Example 6]
In the said Examples 1-5, as shown in FIG. 2, the direction (ZZ direction) orthogonal to the ridgelines 20 and 30 is made into the up-down direction of FIG. However, the direction perpendicular to the ridgelines 20 and 30 (Z-Z direction) may be set to be an arbitrary direction with respect to the casing 2. For example, as shown in FIG. 13, the protrusions 15, 25, 35, and 45 are arranged such that the direction orthogonal to the ridge lines 20 and 30 (Z-Z direction) is inclined at an angle θ with respect to the vertical direction in FIG. It may be provided.

  Since other structures are the same as those in the first to fifth embodiments, description thereof is omitted.

  In Example 6, the same effects as in Examples 1 to 5 are obtained.

[Other Examples]
In the said Examples 1-6, although the 1st inclined surface 16, 16A, 16B and the 2nd inclined surface 17 were formed so that the area might differ, it is good also as the same area.

  Moreover, in the said Examples 1-6, although it formed so that the ridgelines 20 and 30 might become one in the convex parts 15, 25, 35, and 45, for example, a convex part is comprised by shapes, such as a pyramid shape. A three-dimensional shape having a plurality of ridge lines may be used.

  Moreover, in the said Examples 1-6, although the convex parts 15, 25, 35, 45 were comprised with two inclined surfaces, the 1st inclined surface 16, 16A, 16B, and the 2nd inclined surface 17, an inclined surface is It is sufficient if it is plural, and the convex portion may be constituted by three or more inclined surfaces.

  Moreover, in the said Examples 1-6, although the ridgelines 20 and 30 of the convex parts 15, 25, 35, and 45 were made the top 21 by the downstream opening end part 10a side, a convex part is spherical shape, a cone shape, etc. It is good also as a shape which the top of the downstream opening end part 10a side does not have a ridgeline.

  The silencer has a structure in which a projecting portion protruding toward the downstream opening end is provided at a portion facing the downstream opening end in the silencer chamber where the downstream opening end 1 of the inlet pipe is located. If the top of the inlet pipe on the downstream opening end side of the convex portion is not provided on the axis of the central axis of the downstream opening end, it is not limited to the first to sixth embodiments, and may be arbitrarily configured. For example, a resonance chamber may be provided, an inner pipe may be provided, or a plurality of inner plates may be provided.

1 silencer
6,7 Silencer room 10 Inlet pipe
10a Downstream side open end 11 Outlet pipe 15, 25, 35, 45 Convex 16, 16A, 16B, 17 Inclined surface 20, 30 Ridge 21 Top

Claims (3)

In the silencer having an inlet pipe and an outlet pipe whose downstream end is open,
In the muffler chamber where the downstream opening end of the inlet pipe is located, a convex portion that protrudes toward the downstream opening end is provided at a portion facing the downstream opening end.
The silencer is characterized in that the top of the convex portion on the downstream opening end side is not provided on the axis of the central axis of the downstream opening end.   The said convex part has a several inclined surface which inclines with respect to the central axis of a downstream opening end part, The said top was made into the ridgeline by the side of the inlet pipe of an inclined surface, The characterized by the above-mentioned. Silencer. The silencer according to claim 2, wherein the plurality of inclined surfaces have different areas.