JP7192393B2 - engine silencer - Google Patents

Description

The present invention relates to an engine silencer.

Conventionally, various disclosures have been made regarding engine silencers. For example, in Patent Document 1, as a muffler connected to an exhaust system of an internal combustion engine, a plurality of vent holes are formed in a part of an outlet pipe, and a space filled with a sound absorbing material is provided between the outlet pipe and the part. Then, a cover covering the vent hole is provided outside the outlet pipe, and a drain hole is formed in the cover for discharging residual water remaining at the bottom of the shell. As a result, residual water is sucked into the outlet pipe via the space (sound absorbing material) and multiple ventilation holes from the drain hole, so the residual water spouting into the outlet pipe is attenuated and the water surface becomes turbulent. The generation of noise due to

JP-A-2009-13902

In Patent Document 1, a cover having a circular cross section is provided on the outer circumference of the outlet pipe having a circular cross section through a sound absorbing material so as to be concentric with the outlet pipe. A drain hole is formed below the shell (that is, on the bottom side of the shell) (particularly, see FIG. 6).

When the amount of residual water remaining at the bottom of the shell is small (when the level of residual water is low), it is necessary to bring the opening of the drain hole closer to the bottom of the shell in order to suck the residual water into the outlet pipe. Here, as described above, the outlet pipe and the cover both have a circular cross section and are provided concentrically with each other. should be close to the bottom of the However, due to layout constraints, it is often difficult to bring the outlet pipe closer to the bottom of the shell.

SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and its object is to install an exhaust lead-out pipe (outlet pipe) at the bottom of the casing (shell) even when the residual water remaining at the bottom of the casing (shell) is small. To provide an engine silencer capable of sucking residual water into an exhaust lead-out pipe without bringing it closer.

According to the present invention, the horizontal cross section of the holder (cover) is flattened, the longitudinal direction thereof extends toward the bottom of the casing, and a water absorption hole is formed at one end of the longitudinal axis of the holder.

The engine muffler disclosed herein comprises: a casing; an exhaust lead-out pipe formed with a plurality of small holes inside the casing to guide exhaust gas to the outside; A silencer for an engine, comprising: a holder that covers the formed portion from the outside with a gap between it and the pipe wall; and a sound absorbing member that is arranged in the gap and is made of a porous material, The holder has a flat cross-sectional shape with a long axis, and the long axis direction extends toward the bottom of the casing. A water absorption hole is formed to communicate between the inside and the outside of the holder.

According to this, the residual water accumulated in the bottom part of the casing is sucked up through the water absorption holes by capillary action of the sound absorbing member made of a porous material. The sucked-up residual water is sucked into the exhaust outlet pipe through small holes in the wall of the exhaust outlet pipe. Residual water then flows through the exhaust lead-out pipe and is discharged out of the casing.

Therefore, the opening of the water absorption hole can be brought closer to the bottom of the casing without bringing the exhaust outlet pipe closer to the bottom of the casing. That is, even when the amount of residual water accumulated in the bottom of the casing is small (when the water level is low), the residual water can be sucked into the exhaust lead-out pipe.

Here, the term “porous material” refers to a material having a large number of voids that can absorb water by capillary action. Therefore, for example, a spongy porous material having a large number of pores such as a sponge, a fiber aggregate consisting of a large number of short fibers or long fibers, and a large number of voids that can absorb water by capillary action. The configuration may be any as long as it has

In one embodiment, the porous material is composed of a fiber aggregate made of long fibers.

Here, if the porous material in the sound absorbing member is composed of a fiber aggregate composed of short fibers, the high-temperature exhaust gas flowing out from the small holes in the pipe wall of the exhaust lead-out pipe is absorbed by the porous material in the sound absorbing member. Short fibers may be peeled off by blowing through the large number of voids in the direction of the water absorption holes. That is, the number of voids in the porous material is reduced, and the water absorbing performance of the sound absorbing member is reduced. Therefore, by configuring the porous material of the sound absorbing member with a fiber aggregate made of long fibers, it is possible to prevent the water absorption performance of the sound absorbing member from being reduced due to the peeling of the fibers.

In one embodiment, the sound absorbing member includes a first sound absorbing material disposed on one end side of the long axis of the holder in the wall of the exhaust outlet pipe, and a wall of the exhaust outlet pipe and the first sound absorbing member. and a second sound absorbing material arranged so as to wrap around the second sound absorbing material.

Here, the gap between the holder having a flat cross section and the wall of the exhaust lead-out pipe has a flat shape similar to the cross section of the holder when viewed from the central axis direction of the exhaust lead-out pipe. If a sound absorbing member composed of a fiber aggregate of long fibers as a porous material is simply disposed so as to wrap around the wall of the exhaust lead-out pipe, the outer shape of the sound absorbing member is the same as that of the exhaust lead-out pipe. When viewed from the direction of the central axis of the pipe, the shape becomes substantially circular, and it is difficult to insert the sound absorbing member into the vicinity of one end of the long axis of the holder. Therefore, a first sound absorbing material is arranged on one end side of the long axis of the holder on the wall of the exhaust lead-out pipe, and a second sound absorbing material is arranged so as to wrap around the exhaust lead-out pipe and the first sound absorbing material. By providing the first and second sound absorbing members, the overall outer shape of the sound absorbing member combined with the first and second sound absorbing members tends to be the same flat shape as the gap when viewed from the central axis direction of the exhaust lead-out pipe. Therefore, the sound absorbing member (second sound absorbing material) can be packed in the vicinity of one end side of the long axis of the holder, that is, near the water absorbing hole, and the residual water accumulated at the bottom of the casing can be absorbed by the sound absorbing member (second sound absorbing material) near the water absorbing hole. sound absorbing material) can be sucked up reliably by capillary action.

In one embodiment, the holder is composed of two semi-cylindrical shells joined with corresponding outwardly directed joint flanges, and the joint flanges are provided on both ends of the longitudinal axis, The water absorption hole is formed between the joining flanges on one end side of the long axis.

According to this, by providing the sound absorbing member around the exhaust lead-out pipe and sandwiching it between the two shells, the sound absorbing member can be easily packed between the exhaust lead-out pipe and the holder. . Moreover, the joint flanges of the shells can be used to form the water absorption holes, and the joint flanges can be used to bring the openings of the water absorption holes closer to the bottom of the casing.

In one embodiment, the bottom of the casing slopes downwards toward one side and the holder is configured such that the longitudinal direction extends toward the one side of the bottom of the casing. characterized by

According to this, since the bottom of the casing is inclined downward toward one side (for example, the front of the vehicle), residual water can be concentrated and accumulated in the one side of the bottom of the casing. Since one end side (water absorption hole) of the long axis of the holder extends toward the one end of the bottom of the casing where residual water concentrates, residual water can be removed more efficiently.

In one embodiment, a plurality of noise reduction exhaust pipes including the exhaust lead-out pipe are arranged in parallel in one direction within the casing.

In general, there are many cases where a plurality of noise reduction exhaust pipes, including an exhaust lead-out pipe, must be arranged in parallel within the casing. In this case, if the outer diameter of the holder is increased over the entire circumference in order to bring the opening of the water absorption hole closer to the bottom of the casing, due to constraints on the layout of the casing (constraints such as dimensions), the holders will be adjacent to each other to reduce noise. It will interfere with the exhaust pipe for use. On the other hand, the horizontal cross-sectional shape of the holder is flat, and one end of the long axis (water absorption hole) of the holder extends toward the bottom of the casing. The opening of the water absorption hole can be brought closer to the bottom of the casing without interfering with the pipe.

According to the present invention, the horizontal cross-sectional shape of the holder is flat, the longitudinal direction of the holder extends toward the bottom of the casing, and the water absorption hole is formed at one end of the longitudinal axis of the holder. Even if there is little residual water in the bottom of the casing (water level is low), the residual water can be sucked into the exhaust outlet.

FIG. 1 is a schematic configuration diagram showing an exhaust system of an engine in a vehicle equipped with a silencer according to an embodiment of the invention. FIG. 2 is a plan view showing the state of the main silencer viewed from above (however, the inside is shown with the upper casing removed). FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2 (however, the upper casing is represented by a two-dot chain line and the sound absorbing member is omitted). FIG. 4 is an enlarged cross-sectional view showing the periphery of the first exhaust lead-out pipe in FIG. FIG. 5 is a front view showing the first exhaust lead-out pipe with the holder removed (however, the orientation of the holder is reversed so that the joint surface can be seen).

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings. The following description of preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its applicability or its uses.

<Configuration of engine exhaust system>
FIG. 1 shows an exhaust system of an engine in a vehicle equipped with a silencer according to this embodiment. Here, in this specification, the forward/backward direction of the vehicle is referred to as the "front-rear direction", the forward side is referred to as the "front side", and the backward side is referred to as the "rear side". Also, the width direction of the vehicle is defined as the "left-right direction". "Right side" and "left side" are when the vehicle is viewed from the rear side. Also, the vehicle height direction is defined as the "vertical direction". Further, when referring to upstream and downstream, the flow direction of the exhaust gas is used as a reference.

FIG. 1 shows an engine 1 and an exhaust system 10 for the engine 1 in a vehicle. The engine 1 is a horizontal multi-cylinder engine having a plurality of cylinders arranged in the vehicle width direction. The engine 1 is provided in an engine room in front of the vehicle. The engine 1 is provided with an intake system (not shown) on the front side and an exhaust system 10 (see FIG. 1) on the rear side. That is, the engine 1 is also a front intake and rear exhaust engine. The exhaust system 10 is connected to the engine 1 and extends rearward along the lower surface of the vehicle.

The exhaust system 10 includes an exhaust manifold 11 , an exhaust pipe line 12 , catalytic devices 13 and 14 , a pre-silencing device 15 and a main silencer 2 . The exhaust manifold 11 is provided downstream of the engine 1 . The exhaust manifold 11 is a branched end connected at its upstream end to the exhaust port of each cylinder head of the engine 1 . The exhaust manifold 11 collects the exhaust gas discharged from each exhaust port into one passage on the way, and the downstream end is connected to the exhaust pipe line 12 .

The exhaust pipe 12 is a pipe that serves as an exhaust gas passage, is connected to the downstream end of the exhaust manifold 11, and extends rearward. Catalyst devices 13 and 14 and a pre-silencing device 15 are incorporated in the exhaust pipe 12 in this order from the upstream side, and the main silencer 2 is connected to the end. Catalytic devices 13 and 14 purify harmful components in exhaust gas discharged from engine 1 .

The pre-silencer 15 and the main silencer 2 are incorporated in the exhaust system of the engine 1 to reduce exhaust noise. Of the silencers 15 and 2, the pre-silencer 15 arranged on the upstream side has a function of mainly reducing high-frequency components of the exhaust noise. The pre-silencing device 15 can employ, for example, a sound-absorbing type of silencing device. and a sound absorbing material such as glass wool that is filled. On the other hand, the main muffler 2 has a function of mainly reducing low and medium frequency components in the exhaust sound. The structure of the main silencer 2 will be described in detail below.

<Overall Structure of Main Silencer>
FIG. 2 is a plan view showing the state of the main muffler 2 viewed from above (however, the inside is shown with the exception of an upper casing 21, which will be described later). 3 is a cross-sectional view (that is, a right cross-sectional view) taken along line III-III of FIG. 2. FIG. However, an upper casing 21, which will be described later, is represented by a phantom line, and sound absorbing members 90 and 94, which will be described later, are omitted. The main silencer 2 has a casing 20 . The casing 20 has a two-split structure, in which a substantially box-shaped upper casing 21 (see FIG. 3) constituting an upper portion and a substantially box-shaped lower casing 22 constituting a lower portion are respectively provided. The flange portions 21a and 22a provided on the periphery of the opening of the are joined to each other.

The casing 20 defines a muffling space S inside. As shown in FIGS. 2 and 3 , the casing 20 has a flat and rounded rectangular parallelepiped shape that is relatively short in the vertical and longitudinal directions and relatively long in the horizontal direction (vehicle width direction). As a result, the silencer space S in the casing 20 also forms a flat gap elongated in the left-right direction.

The casing 20 includes, as walls defining the muffling space S, a front wall portion 23 and a rear wall portion 24 aligned in the longitudinal direction of the vehicle, a right wall portion 25 and a left wall portion 26 aligned in the left-right direction, and an upper wall portion 25 and a left wall portion 26 aligned in the vertical direction. It has a wall portion 27 and a bottom wall portion 28 . The front wall portion 23 is a wall linearly extending in the left-right direction. The rear wall portion 24 is a wall that extends in the left-right direction and has curved portions 24a, 24a on both left and right sides, curving in a gently convex shape toward the rear when viewed from above. The right wall portion 25 and the left wall portion 26 are short walls extending linearly in the front-rear direction, and connect the front wall portion 23 and the rear wall portion 24 at the right end side and the left end side, respectively. The upper wall portion 27 closes the upper surface of the space surrounded by the side walls composed of the front wall portion 23 , the rear wall portion 24 , the right wall portion 25 and the left wall portion 26 . The bottom wall portion 28 closes the lower surface of the space surrounded by the side walls.

As shown in FIG. 3, the casing 20 has a streamlined rear side. That is, the rear wall portion 24 gently curves upward in the rearward direction. Further, as shown in FIG. 3, the bottom wall portion 28 of the casing 20 is inclined forward. Specifically, the bottom wall portion (bottom portion) 28 of the casing 20 is inclined downward toward the front side (one side) at an inclination angle α with respect to the horizontal. By inclining the bottom wall portion 28 in this way, the residual water W in the casing 20 is collected in a concentrated manner in the water reservoir portion 28a on the front side of the bottom wall portion 28 of the casing 20, although the details will be described later. there is

As shown in FIG. 2, a bottom wall portion 28 of the lower casing 22 is formed with a plurality of uneven portions 29, 29, . . . extending in the front-rear direction. The concave-convex portion 29 has a groove shape that is convex toward the muffling space S inside the casing 20 (that is, concave toward the outside of the casing 20 ), and has the effect of increasing the rigidity of the casing 20 . Similarly, although not shown, the upper wall portion 27 of the upper casing 21 is also formed with a plurality of uneven portions 29 extending in the front-rear direction.

As shown in FIG. 2, an exhaust introduction pipe 40, a first exhaust lead-out pipe 50, and a second exhaust lead-out pipe 60 are arranged in the casing 20 as noise reduction exhaust pipes. The exhaust introduction pipe 40, the first exhaust lead-out pipe 50, and the second exhaust lead-out pipe 60 are pipes independent of each other.

The exhaust introduction pipe 40 is connected at its upstream end to the downstream end of the exhaust pipe line 12, as shown in FIG. Specifically, as shown in FIG. 2, the exhaust introduction pipe 40 is configured by a straight pipe portion 41 that penetrates the front wall portion 23 near the center in the left-right direction at its upstream end. The upstream end of the straight pipe portion 41 is flange-connected to the downstream end of the exhaust pipe line 12 outside the casing 20 . The straight pipe portion 41 extends in the front-rear direction and penetrates through a through hole 23 a formed in the front wall portion 23 . The through hole 23a is formed in a circular shape by aligning semicircular notches formed in the front wall portions 23 of the upper casing 21 and the lower casing 22 in opposite directions. Moreover, the through hole 23 a not only allows the straight pipe portion 41 to pass through, but also serves as a support portion for supporting the straight pipe portion 41 .

The exhaust introduction pipe 40 has a bent pipe portion 42 at its intermediate portion. Specifically, the bent pipe portion 42 has its upstream end connected to the downstream end of the straight pipe portion 41 . The curved pipe portion 42 is bent in the front-rear direction and the left-right direction from its upstream end to its downstream end. A downstream end portion of the exhaust introduction pipe 40 is configured with a straight pipe portion 43 . Specifically, the straight pipe portion 43 is connected at its upstream end to the downstream end of the curved pipe portion 42 . The straight pipe portion 43 extends in the left-right direction near the front wall portion 23 inside the casing 20 , and its downstream end is positioned near the left wall portion 26 . An exhaust outlet 44 opens at the downstream end of the straight pipe portion 43 . That is, the exhaust introduction pipe 40 communicates, at its downstream end, with a silencer space S (more specifically, a resonance chamber S1, which will be described later) inside the casing 20 .

As shown in FIG. 2, the straight pipe portion 43 is divided into three parts, an upstream portion 43a, an intermediate portion 43b, and a downstream portion 43c, from the upstream end to the downstream end. The intermediate portion 43b has a plurality of small holes 45, 45, . That is, the inside and outside of the exhaust introduction pipe 40 communicate with each other through a plurality of small holes 45 opened in the pipe wall of the intermediate portion 43b. The small holes 45 are not opened in the pipe walls of the upstream portion 43a and the downstream portion 43c.

The exhaust introduction pipe 40 is inclined upward toward the downstream direction so that the exhaust outlet 44 faces slightly upward. This is because moisture (condensed water) in the exhaust gas condensed in the muffling space S may remain on the bottom wall portion 28 of the casing 20, and the residual water W flows back into the exhaust introduction pipe 40 through the exhaust outlet port 44. This is to avoid

A first exhaust lead-out pipe 50 is arranged on the rear side of the exhaust lead-in pipe 40, as shown in FIG. The first exhaust lead-out pipe 50 has a straight pipe portion 51 at its upstream end. The straight pipe portion 51 extends in the left-right direction, and is disposed behind the straight pipe portion 43 of the exhaust introduction pipe 40 in parallel with the straight pipe portion 43 in the front-rear direction. The straight pipe portion 51 has its upstream end located on the right side in the left-right direction of the straight pipe portion 41 of the exhaust introduction pipe 40 in the casing 20 . An exhaust inlet 52 opens at the upstream end of the straight pipe portion 51 . In other words, the upstream end of the first exhaust lead-out pipe 50 communicates with the muffling space S inside the casing 20 (more specifically, the expansion chamber S2, which will be described later). The inner diameter of the exhaust inlet 52 is enlarged like a bell mouth in order to smoothly introduce the exhaust gas into the exhaust inlet 52 . Further, as shown in FIG. 2, the straight pipe portion 51 is divided into two parts, an upstream portion 51a and a downstream portion 51b, from the upstream end to the downstream end. As shown in FIG. 3, the upstream portion 51a has a pipe wall 51c. A plurality of small holes 53, 53, . . . That is, the inside and the outside of the first exhaust lead-out pipe 50 communicate with each other through a plurality of small holes 53 opened in the pipe wall 51c of the upstream portion 51a. The pipe wall 51c is covered with the holder 70 over the entire circumference via the sound absorbing member 90, although the details will be described later. The small holes 53 are not opened in the pipe wall of the downstream portion 51b.

An intermediate portion of the first exhaust lead-out pipe 50 is composed of a bent pipe portion 54 . Specifically, the upstream end of the bent pipe portion 54 is connected to the downstream end of the straight pipe portion 51 at a position slightly rightward in the left-right direction with respect to the downstream end (exhaust outlet 44) of the exhaust introduction pipe 40. ing. The curved pipe portion 54 is curved and contacted in the left-right direction at its upstream portion 54a. The curved pipe portion 54 extends diagonally rearward to the left at its intermediate portion 54b. The bent pipe portion 54 bends and contacts in the front-rear direction from the left oblique rear direction at its downstream portion 54c. Here, the curved tube portion 54 penetrates the left curved portion 24a of the rear wall portion 24 at the intermediate portion 54b. Specifically, a through hole 24b is formed in the curved portion 24a on the left side of the rear wall portion 24, and an intermediate portion 54b of the bent pipe portion 54 penetrates through the through hole 24b. Similar to the through hole 23a of the front wall portion 23 described above, the through hole 24b is a semicircular notch formed in the left curved portion 24a of the rear wall portion 24 of the upper casing 21 and the lower casing 22. They are formed in a circular shape by being put together in opposite directions. Moreover, the through hole 24b not only allows the intermediate portion 54b to pass through, but also serves as a support portion for supporting the intermediate portion 54b.

A downstream end portion of the first exhaust lead-out pipe 50 is composed of a straight pipe portion 55 . Specifically, the straight pipe portion 55 is connected at its upstream end to the downstream end of the curved pipe portion 54 outside the casing 20 . The straight pipe portion 55 extends rearward outside the casing 20 , and the downstream side (rear side) of the straight pipe portion 55 is constituted by a tail pipe 55 a having a diameter larger than that of the other portion of the straight pipe portion 55 . An exhaust outlet 56 opens at the downstream end of the tail pipe 55a (that is, the downstream end of the first exhaust lead-out pipe 50). That is, the first exhaust lead-out pipe 50 communicates with the atmosphere outside the casing 20 at its downstream end.

A second exhaust lead-out pipe 60 is arranged behind the first exhaust lead-out pipe 50 . The second exhaust lead-out pipe 60 has a straight pipe portion 61 at its upstream end. The straight pipe portion 61 extends in the left-right direction and is disposed near the rear wall portion 24 inside the casing 20 . Specifically, the straight pipe portion 61 is arranged in parallel with the straight pipe portion 43 of the exhaust introduction pipe 40 and the straight pipe portion 51 of the first exhaust outlet pipe 50 in the front-rear direction, and between the straight pipe portions 51 , which will be described later. They are arranged with a gap large enough for the straight pipe portion 64 to enter. The upstream end of the straight pipe portion 61 is located in the vicinity of the curved portion 24a on the right side of the rear wall portion 24 in the casing 20 and substantially at the same position in the left-right direction as the upstream end (exhaust inlet 52) of the first exhaust lead-out pipe 50. do. An exhaust inlet 62 is open at the upstream end of the straight pipe portion 61 . That is, the second exhaust lead-out pipe 60 communicates at its upstream end with the silencer space S inside the casing 20 (more specifically, an expansion chamber S2, which will be described later). The inner diameter of the exhaust inlet 62 is enlarged like a bell mouth in order to smoothly introduce the exhaust gas into the exhaust inlet 62 .

A bent pipe portion 63 is formed on the upstream side of the second exhaust lead-out pipe 60 . Specifically, the curved pipe portion 63 has its upstream end connected to the downstream end of the straight pipe portion 61 near the center in the left-right direction near the rear wall portion 24 in the casing 20 . The curved pipe portion 63 is curved to make a U-turn from its upstream end to its downstream end, and its downstream end is connected to the upstream end of the straight pipe portion 64 . The straight pipe portion 64 constitutes an intermediate portion of the second exhaust lead-out pipe 60, and extends between the straight pipe portion 61 and the straight pipe portion 51 of the first exhaust lead-out pipe 50 with the straight pipe portions 51, 61 in the longitudinal direction. extends in the left-right direction parallel to the .

As shown in FIG. 2, the straight pipe portion 64 of the second exhaust lead-out pipe 60 is divided into three parts, an upstream portion 64a, an intermediate portion 64b, and a downstream portion 64c, from the upstream end to the downstream end. The intermediate portion 64b is positioned at substantially the same position in the horizontal direction as the upstream portion 51a of the straight pipe portion 51 of the first exhaust lead-out pipe 50. As shown in FIG. 65, . . . are open over the entire circumference. That is, the inside and the outside of the second exhaust lead-out pipe 60 communicate with each other through a plurality of small holes 65 opened in the pipe wall of the intermediate portion 64b. The pipe wall, which will be described later in detail, is covered with a holder 81 over its entire circumference with a sound absorbing member 94 interposed therebetween. The small holes 65 are not opened in the pipe walls of the upstream portion 64a and the downstream portion 64c.

A curved pipe portion 66 is formed on the downstream side of the second exhaust lead-out pipe 60 . Specifically, the curved pipe portion 66 has its upstream end connected to the downstream end of the straight pipe portion 64 near the curved portion 24 a on the right side of the rear wall portion 24 in the casing 20 . The curved pipe portion 66 is curved and contacted in the right and left oblique rearward direction at its upstream portion 66a. The curved pipe portion 66 extends diagonally rearward to the right at its intermediate portion 66b. The bent pipe portion 66 bends and contacts in the front-rear direction from the right oblique rear direction at its downstream portion 66c. Here, the curved tube portion 66 penetrates the curved portion 24a on the right side of the rear wall portion 24 at the intermediate portion 66b. Specifically, a through-hole 24b is formed in the curved portion 24a on the right side of the rear wall portion 24, and an intermediate portion 66b of the curved tube portion 66 penetrates through the through-hole 24b. The through-hole 24b not only allows the intermediate portion 66b to pass through, but also serves as a support portion for supporting the intermediate portion 66b.

A downstream end portion of the second exhaust lead-out pipe 60 is composed of a straight pipe portion 67 . Specifically, the straight pipe portion 67 is connected at its upstream end to the downstream end of the curved pipe portion 66 outside the casing 20 . The straight pipe portion 67 extends rearward outside the casing 20 , and the downstream side (rear side) of the straight pipe portion 67 is constituted by a tail pipe 67 a having a larger diameter than the other portions of the straight pipe portion 67 . An exhaust outlet 68 opens at the downstream end of the tail pipe 67a (that is, the downstream end of the second exhaust lead-out pipe 60). That is, the second exhaust lead-out pipe 60 communicates with the atmosphere outside the casing 20 at its downstream end.

The first exhaust lead-out pipe 50 and the second exhaust lead-out pipe 60 are slanted downward toward the downstream direction so that the exhaust outlets 56 and 68 face slightly downward. This causes water, such as residual water W, and foreign matter, which have entered the first and second exhaust lead-out pipes 50 and 60, to flow downstream along the downward slope and out of the casing 20 from the exhaust outlets 56 and 68. It is for discharge.

As shown in FIG. 3, the exhaust lead-in pipe 40, the first exhaust lead-out pipe 50 and the second exhaust lead-out pipe 60 are composed of straight pipe portions 43, 51, 61 and 64 (a plurality of silencers including the first exhaust lead-out pipe 50). exhaust pipe) are located at substantially the same height and arranged in parallel in the front-rear direction (one direction) within the casing 20 . As described above, the casing 20 has a flat rectangular parallelepiped shape that is relatively short in the vertical and front-rear directions and relatively long in the left-right direction. In many cases, the piping must be arranged in parallel in the front-rear direction.

As shown in FIG. 2, the muffling space S is partitioned by a partition plate 30 into a resonance chamber S1 and an expansion chamber S2. Specifically, the partition plate 30 is a plate-like member, and is provided so as to extend in the front-rear direction at the boundary position between the intermediate portion 43b and the downstream portion 43c of the straight pipe portion 43 of the exhaust introduction pipe 40 in the left-right direction. ing. The edge portions of the partition plate 30 are airtightly fixed to the front wall portion 23 , the rear wall portion 24 , the upper wall portion 27 and the bottom wall portion 28 of the casing 20 . As a result, the muffling space S is partitioned into a resonance chamber S1 on the left side of the partition plate 30 and an expansion chamber S2 on the right side thereof. The expansion chamber S2 has a larger volume than the resonance chamber S1. The volumes of the resonance chamber S1 and the expansion chamber S2 are adjusted according to the frequency of the exhaust sound to be silenced. As shown in FIG. 2 , the straight pipe portion 43 of the exhaust introduction pipe 40 and the straight pipe portion 51 of the first exhaust outlet pipe 50 pass through the partition plate 30 . Specifically, although not shown, the partition plate 30 is formed with two through holes, through which the straight pipe portions 43 and 51 pass.

As shown in FIG. 2, support plates 31 to 35 for supporting the exhaust introduction pipe 40, the first exhaust outlet pipe 50 and the second exhaust outlet pipe 60 are arranged in the casing 20. As shown in FIG. The support plates 31 to 35 are plate-like members provided to extend in the front-rear direction. The edge portions of the support plates 31 to 35 are fixed to the upper wall portion 27 and the bottom wall portion 28 of the casing 20 (or to the front wall portion 23 and the rear wall portion 24 depending on the support plate). The support plates 31 to 35 are formed with through holes through which the exhaust introduction pipe 40, the first exhaust outlet pipe 50 and the second exhaust outlet pipe 60 pass. These through-holes also serve as support portions for supporting the exhaust introduction pipe 40 , the first exhaust lead-out pipe 50 and the second exhaust lead-out pipe 60 . Further, the support plates 31 to 35 increase the rigidity of the casing 20 and suppress vibration of the casing 20 (wall vibration). The number and positions of the support plates 31 to 35 may be appropriately determined according to the length and weight of the exhaust introduction pipe 40, the first exhaust outlet pipe 50 and the second exhaust outlet pipe 60, and the like. Further, holes other than the through holes may be formed in the support plates 31-35. The main muffler 2 is connected to the vehicle body by connecting members 36 to 38 (see FIG. 2) provided outside the left and right walls 25 and 26 of the casing 20 and at the curved pipe portion 54 of the first exhaust lead-out pipe 50. are connected.

<Structure of Holder Covering First Exhaust Lead-out Pipe>
As described above, a plurality of small holes 53, 53, . . . It is covered (see Figures 3 and 4). Specifically, as shown in detail in FIG. 4, the holder 70 has a flat shape with a substantially elliptical cross-sectional shape, and the pipe wall 51c of the first exhaust lead-out pipe 50 (upstream portion 51a) is It covers the entire circumference from the outside with a gap 71 between it and the pipe wall 51c. The longitudinal direction of the holder 70 extends in the left-right direction, and the holder 70 has a substantially elliptical cylindrical shape that covers the pipe wall 51c of the first exhaust lead-out pipe 50 (upstream portion 51a) in the left-right direction. The holder 70 has a flattened cross section, so it has a major axis 72 and a minor axis 73 that extends perpendicularly to the major axis 72 and is shorter than the major axis 72 . Here, as described above, the bottom wall portion 28 of the casing 20 is inclined downward toward the front side at an inclination angle α with respect to the horizontal. The front side of the bottom wall portion 28 serves as a water reservoir portion 28a in which residual water W in the casing 20 is concentrated and stored. 4, the lower end (one end) 72a of the long shaft 72 extends from the first exhaust lead-out pipe 50 (upstream portion 51a) to the front side of the bottom wall (bottom) 28 of the casing 20. The long axis 72 is provided at an angle of inclination β with respect to the vertical so as to extend toward the portion 28a (one of the bottom portions of the casing 20).

The intersection of the long axis 72 and the short axis 73 is the axial center 74 of the holder 70 . As shown in FIG. 4, the axis 74 is eccentric with respect to the axis 51d of the first exhaust lead-out pipe 50 (upstream portion 51a). Specifically, the axis 74 of the holder 70 is eccentric so as to be closer to the water reservoir 28 a on the front side of the bottom wall 28 of the casing 20 than the axis 51 d of the first exhaust lead-out pipe 50 .

The holder 70, as shown in FIG. 4, is formed by joining two semi-cylindrical shells 70A, 70B with corresponding outwardly directed joining flanges 75A, 75B and mutually corresponding outwardly directed joining flanges 76A, 76B. ing. Specifically, the holder 70 has two semi-cylindrical first and second shells 70A and 70B divided into front and rear sides of the long axis 72 of the holder 70 with the long axis 72 as a boundary. formed together. The first and second shells 70A, 70B are provided at the lower ends 72a of their longitudinal axes 72 with corresponding outwardly facing joining flanges 75A, 75B. Similarly, the first and second shells 70A, 70B are provided with corresponding outwardly directed joining flanges 76A, 76B at the upper ends 72b of their longitudinal axes 72, respectively. That is, the joint flanges 75A, 75B and the joint flanges 76A, 76B are provided at both end portions 72a, 72b of the long axis 72 of the first and second shells 70A, 70B (holder 70).

FIG. 5 shows a state where the holder 70 is divided into a first shell 70A and a second shell 70B and the holder 70 is removed from the first exhaust lead-out pipe 50. As shown in FIG. The lower ends 72a of the long shafts 72 of the first and second shells 70A, 70B are provided with outwardly facing joining flanges 75A, 75B, respectively. The joint surfaces 77A and 77B of these joint flanges 75A and 75B are joined to each other. Similarly, the upper ends 72b of the longitudinal axes 72 of the first and second shells 70A, 70B are provided with outwardly directed joining flanges 76A, 76B, respectively. The joint surfaces 78A and 78B of these joint flanges 76A and 76B are joined to each other. 5, the direction is reversed so that the joint surfaces 77A, 77B, 78A, 78B of the joint flanges 75A, 75B, 76A, 76B of the first and second shells 70A, 70B can be seen.

As shown in FIG. 5, on the joint surface 77A of the joint flange 75A on the lower end portion 72a side of the long shaft 72 of the first shell 70A, two grooves extending in the inward and outward directions are provided at positions slightly away from the central portion in the longitudinal direction on both sides. Two grooves 79A, 79A are formed. The grooves 79A, 79A have a substantially semicircular cross-section with rounded bottoms. Similarly, on the joint surface 77B of the joint flange 75B on the lower end portion 72a side of the long shaft 72 of the second shell 70B, two grooves 79B extending in the inward and outward directions are provided at positions slightly spaced from the center in the longitudinal direction on both sides. 79B is formed. The grooves 79B, 79B correspond to the grooves 79A, 79A, and, like the groove 79A, have a substantially semicircular cross section with a rounded bottom. No groove is formed in the joint surfaces 78A and 78B of the joint flanges 76A and 76B.

The grooves 79A, 79A and grooves 79B, The openings of 79B are aligned with each other, and two water absorption holes 80, 80 having a substantially circular cross section are formed between the joint flanges 75A, 75B to communicate the inside and the outside of the holder 70 (see FIG. 4).

<Structure of Sound Absorption Member of First Exhaust Lead-out Pipe>
As schematically shown in FIG. 4, a sound absorbing member 90 is arranged in a gap 71 between the pipe wall 51c of the upstream portion 51a of the straight pipe portion 51 of the first exhaust lead-out pipe 50 and the holder 70. . Here, the gap 71 between the holder 70 having a flat cross section and the pipe wall 51c of the first exhaust lead-out pipe 50 (upstream portion 51a) extends from the central axis direction of the first exhaust lead-out pipe 50 (upstream portion 51a). When viewed, it has a flat shape similar to the cross section of the holder 70 . The sound absorbing member 90 includes a first sound absorbing material 91 and a second sound absorbing material 92 .

The first sound absorbing material 91 is formed by winding a large number of long fiber glass wools 91a, 91a, ... extending in the same direction around a rod-like core material a plurality of times, extracting the core material from the long fiber 91a, and compressing the core material in the radial direction. It is a formed fiber assembly, and its shape is a substantially rod-like shape having a length 91b (see FIG. 5). As shown in FIG. 4, the first sound absorbing material 91 is fixed to the lower end portion 72a side of the long shaft 72 of the holder 70 on the pipe wall 51c of the first exhaust lead-out pipe 50 (upstream portion 51a).

As shown in FIGS. 4 and 5, the second sound absorbing material 92 includes a large number of long fiber glass wools 92a, 92a, . It is a fiber aggregate that is arranged so as to be wound many times around the first sound absorbing material 91 fixed to the wall 51c. The second sound absorbing material 92 has a substantially elliptical flat shape with a major axis 92b when viewed from the central axis direction of the first exhaust lead-out pipe 50 (upstream portion 51a). The sound absorbing member 90 formed by combining the first sound absorbing material 91 and the second sound absorbing material 92 also has an overall external shape that is long when viewed from the central axis direction of the first exhaust lead-out pipe 50 (upstream portion 51a). It has a substantially elliptical flat shape with an axis 93 . Further, as shown in FIG. 4, the lower end portion 93a of the long shaft 93 of the sound absorbing member 90 is substantially aligned with the lower end portion 72a of the long shaft 72 of the holder . As a result, the sound absorbing member 90 (second sound absorbing material 92) can also be filled in the vicinity of the water absorption hole 80 (near the lower end portion 72a of the long shaft 72 of the holder 70). Further, as shown in FIG. 5, the first sound absorbing material 91 extends along the longitudinal direction of the first exhaust lead-out pipe 50 (upstream portion 51a) (the length 92b direction coincides with the central axis direction of the upstream portion 51a). ) and is fixed to the pipe wall 51c. As a result, the second sound absorbing material 92 can be wound around the pipe wall 51c and the first sound absorbing material 91 over a sufficient length in the longitudinal direction of the first exhaust lead-out pipe 50 (upstream portion 51a). . Then, the sound absorbing member 90 can be formed in a substantially elliptical tubular shape having a sufficient length 91b.

As described above, the first sound absorbing material 91 is a fiber assembly formed by winding or compressing a large number of long fibers 91a, 91a, . . . extending in the same direction. That is, the first sound absorbing material 91 has a large number of voids formed between the long fibers 91a of the large number of long fibers 91a, 91a, . The second sound absorbing material 92 is also a fiber assembly formed by winding a large number of long fibers 92a, 92a, ... extending in the same direction, and has a large number of gaps formed between the long fibers 92a. In other words, the fiber assembly composed of the long fibers 91a and 92b in the first and second sound absorbing materials 91 and 92 constitutes a porous material. Therefore, the first and second sound absorbing materials 91 and 92 (sound absorbing member 90) are "sound absorbing materials made of porous material" in which a large number of voids are formed to the extent that water can be absorbed by capillary action. I can say.

<Structure of Holder and Sound Absorption Member of Second Exhaust Lead-out Pipe>
As shown in FIGS. 2 and 3, the pipe wall in which a plurality of small holes 65, 65, . . . 81 covered. As shown in FIGS. 2 and 3, the holder 81 has a substantially cylindrical shape whose longitudinal direction is the left-right direction with a circular cross-sectional shape. is left open and covered from the outside. Also, the axis of the holder 81 coincides with the axis of the intermediate portion 64b.

As schematically shown in FIG. 4, a sound absorbing member 94 is arranged in the gap between the pipe wall of the intermediate portion 64b of the straight pipe portion 64 of the second exhaust lead-out pipe 60 and the holder 81. As shown in FIG. The sound absorbing member 94 is a fiber assembly in which long-fiber glass wool is wound around the wall of the second exhaust lead-out pipe 60 (intermediate portion 64b) in multiple layers, and has a substantially cylindrical shape. ing. Since the sound absorbing member 94 has the same structure as the first and second sound absorbing members 91 and 92, it can be called "a sound absorbing member made of a porous material".

<Action and effect of the embodiment>
(Regarding exhaust noise reduction with the main silencer)
As shown in FIG. 1, the exhaust gas discharged from the combustion chamber of the engine 1 passes through the exhaust manifold 11, the exhaust pipe line 12, the catalyst devices 13 and 14, and the pre-silencing device 15, and passes through the exhaust introduction pipe of the main silencer 2. Introduced in 40. Exhaust gas introduced into the exhaust introduction pipe 40 flows into the expansion chamber S2 through a plurality of small holes 45, 45, . . . At this time, exhaust noise is reduced by the expansion action of the exhaust gas. Further, as shown in FIG. 2, an exhaust outlet 44 of the exhaust introduction pipe 40 opens to face the resonance chamber S1. This reduces the specific frequency component of the exhaust sound.

Exhaust gas that has flowed into the expansion chamber S2 flows rightward in the expansion chamber S2, part of which is introduced from the exhaust inlet 52 into the first exhaust lead-out pipe 50, and part of it is led from the exhaust inlet 62 to the second exhaust lead-out. Introduced into tube 60 . Here, as described above, the exhaust inlets 52, 62 have their inner diameters enlarged in a bellmouth shape, so that the exhaust gas can be smoothly introduced into the first and second exhaust lead-out pipes 50, 60. can.

A part of the exhaust gas that has flowed into the first exhaust lead-out pipe 50 passes through a plurality of small holes 53, 53, . . . Exhaust sound is absorbed by flowing to the outer sound absorbing member 90 . In the first exhaust lead-out pipe 50, the remaining exhaust gas that has not passed through the small holes 53 and has not flowed outside the pipe wall 51c flows directly through the first exhaust lead-out pipe 50 in the downstream direction, and reaches the exhaust outlet 56 of the tail pipe 55a. is discharged to the atmosphere outside the casing 20 (leads out to the outside). Similarly, part of the exhaust gas that has flowed into the second exhaust lead-out pipe 60 passes through a plurality of small holes 65, 65, . . . Exhaust sound is absorbed by flowing to the sound absorbing member 94 on the outside of the . In the second exhaust lead-out pipe 60, the remaining exhaust gas that has not passed through the small holes 65 and has not flowed to the outside of the pipe wall flows directly through the second exhaust lead-out pipe 60 in the downstream direction, and reaches the exhaust outlet 68 of the tail pipe 67a. is discharged to the atmosphere outside the casing 20 (leads out to the outside).

(Regarding absorption of residual water)
In the main silencer 2 , water contained in the exhaust gas is condensed and accumulated as residual water W on the bottom wall portion 28 of the casing 20 . As described above, the bottom wall portion 28 of the casing 20 is inclined downward toward the front at an inclination angle α with respect to the horizontal axis (see FIGS. 3 and 4). That is, as shown in FIG. 4, the residual water W concentrates and accumulates in the front-side water pool portion 28a of the bottom wall portion 28 of the casing 20. As shown in FIG.

Here, as described above, the holder 70 covering the pipe wall 51c in which the plurality of small holes 53, 53, . . . has a flat shape, and a lower end portion 72a of its long axis 72 extends toward the water reservoir portion 28a (see FIG. 4). As a result, the lower end 72a is located near the water reservoir 28a. A water absorption hole 80 communicating between the inside and the outside of the holder 70 is formed between the outward joining flanges 75A and 75B on the lower end portion 72a side of the long shaft 72 of the holder 70 .

Since the water absorption hole 80 is located near the water reservoir 28a, the sound absorbing member 90 inside the holder 70 is particularly affected by the portion near the water absorption hole 80 (the portion near the lower end 72a of the long shaft 72 in the holder 70). , is easily immersed in the residual water W accumulated in the water reservoir 28a (see FIG. 4). Therefore, when the portion of the sound absorbing member 90 (second sound absorbing member 92) in the vicinity of the water absorbing holes 80 is immersed in the residual water W accumulated in the water reservoir 28a, the residual water W is absorbed into the sound absorbing member 90 made of the porous material. Water is drawn up through the water absorption holes 80 by capillary action. The sucked-up residual water W is sucked into the first exhaust lead-out pipe 50 through a plurality of small holes 53, 53, . . .

As described above, the first exhaust lead-out pipe 50 is slanted downward in the downstream direction so that the exhaust outlet 56 faces slightly downward. Therefore, the residual water W sucked into the first exhaust lead-out pipe 50 flows downstream through the first exhaust lead-out pipe 50 . The residual water W is then discharged out of the casing 20 through the exhaust outlet 56 .

With this configuration, the opening of the water absorption hole 80 can be brought closer to the water reservoir 28a on the front side of the bottom wall portion 28 of the casing 20 without bringing the first exhaust outlet pipe 50 closer to the water reservoir 28a. That is, even when the residual water W accumulated in the water reservoir 28a is small (when the water level is low), the residual water W can be sucked into the first exhaust lead-out pipe 50. Furthermore, since the residual water W can be collected in a concentrated manner in the water reservoir 28a of the bottom wall 28 of the casing 20, the residual water W can be removed more efficiently.

As described above, the porous material in the sound absorbing member 90 (the first and second sound absorbing materials 91 and 92) is composed of a fiber assembly made up of long fibers 91a and 92a. Here, if the porous material in the sound absorbing member 90 is composed of a fiber assembly composed of short fibers, the high temperature gas flowing out from the small holes 53 of the pipe wall 51c of the first exhaust lead-out pipe 50 (upstream portion 51a) The exhaust gas passes through many voids of the porous material of the sound absorbing member 90 and blows through toward the water absorption holes 80, which may cause the short fibers to come off. That is, the number of voids in the porous material is reduced, and the water absorbing performance of the sound absorbing member 90 is reduced. Therefore, by configuring the porous material of the sound absorbing member 90 with a fiber assembly composed of the long fibers 91a and 92a, it is possible to prevent the water absorption performance of the sound absorbing member 90 from being reduced due to the peeling of the fibers.

As described above, the gap 71 between the holder 70 having a flat cross section and the pipe wall 51c of the first exhaust lead-out pipe (upstream portion 51a) extends in the central axis direction of the first exhaust lead-out pipe 50 (upstream portion 51a). When viewed from above, it has a flat shape similar to the cross section of the holder 70 . Here, it is assumed that the sound absorbing member in which the porous material is composed of a fiber assembly made of long fibers is simply arranged so as to wrap around the pipe wall 51c of the first exhaust lead-out pipe 50 (upstream portion 51a). In this case, the outer shape of the sound absorbing member becomes substantially circular when viewed from the central axis direction of the first exhaust lead-out pipe 50 (upstream portion 51a), and the sound absorption extends to the vicinity of the lower end portion 72a of the long axis 72 of the holder 70. Difficult to pack parts. Therefore, the first sound absorbing material 91 is fixed to the lower end portion 72a side of the long axis 72 of the holder 70 in the pipe wall 51c of the first exhaust lead-out pipe 50 (upstream portion 51a). and the first sound absorbing material 91 are put together and the second sound absorbing material 92 is disposed so as to wrap around the first sound absorbing material 91, so that the overall shape of the sound absorbing member 90 formed by combining the first and second sound absorbing materials 91 and 92 is , the first exhaust lead-out pipe 50 (upstream portion 51a) tends to have the same flat shape as the gap 71 when viewed from the central axis direction. Therefore, the sound absorbing member 90 (second sound absorbing material 92) can be packed in the vicinity of the lower end 72a of the long shaft 72 of the holder 70, that is, in the vicinity of the water absorption hole 80, and the water reservoir 28a on the front side of the bottom wall 28a of the casing 20. The residual water W accumulated in the water absorption hole 80 can be reliably sucked up by the capillary phenomenon of the sound absorbing member 90 (second sound absorbing member 92) near the water absorption hole 80.

With the structure of the holder 70, the sound absorbing member 90 is provided around the first exhaust lead-out pipe 50 (upstream portion 51a), and by sandwiching this between the two shells 70A and 70B, the first exhaust lead-out pipe 50 can be easily installed. A sound absorbing member 90 can be packed between (the upstream portion 51 a ) and the holder 70 . Moreover, the joint flanges 75A and 75B of the first and second shells 70A and 70B can be used to form the water absorption holes 80, and the joint flanges 75A and 75B can be used to cover the openings of the water absorption holes 80. 20 can be brought close to the water reservoir 28a on the front side of the bottom wall 28 of 20.

Here, in general, it is often the case that a plurality of noise reduction exhaust pipes including the first exhaust lead-out pipe 50 must be arranged in parallel in the casing 20 as in the present embodiment. In this case, if the outer diameter of the holder 70 were increased over the entire circumference in order to bring the opening of the water absorption hole 80 closer to the water reservoir 28a on the front side of the bottom wall 28 of the casing 20, the layout of the casing 20 would be limited. Due to (restrictions such as dimensions), the holder 70 interferes with the adjacent exhaust pipes for muffling (the straight pipe portion 43 of the exhaust introduction pipe 40 and the straight pipe portion 64 of the second exhaust lead-out pipe 60). On the other hand, the holder 70 has a flat cross-sectional shape, and the lower end 72a (water absorption hole 80) of the long shaft 72 of the holder 70 extends from the first exhaust lead-out pipe 50 to the front side of the bottom wall portion 28 of the casing 20. Since the holder 70 is configured to extend toward the water reservoir 28a, the holder 70 is caused to interfere with the adjacent noise reduction exhaust pipes (the straight pipe portion 43 of the exhaust introduction pipe 40 and the straight pipe portion 64 of the second exhaust lead-out pipe 60). The opening of the water absorption hole 80 can be brought closer to the water reservoir portion 28a without removing the water.

(Other embodiments)
In the above-described embodiment, the cross-sectional shape of the holder 70 is substantially elliptical, but it does not necessarily have to be substantially elliptical, and may be any shape as long as it is flat. For example, it may have a substantially rectangular shape, in which case the center line in the long side direction may be the major axis, and the center line in the short side direction may be the minor axis.

In the above-described embodiment, the axis 74 of the holder 70 and the axis 51d of the first exhaust lead-out pipe 50 (upstream portion 51a) are eccentric, but they do not necessarily have to be eccentric and may coincide with each other. In this case, the first sound absorbing material 91 may be arranged on the lower end portion 72a and upper end portion 72b side of the long shaft 72 of the holder 70 on the pipe wall 51c of the first exhaust lead-out pipe 50 (upstream portion 51a).

In the above-described embodiment, both the first sound absorbing material 91 and the second sound absorbing material 92 are composed of fiber aggregates made of long fibers 91a and 92a. , may be composed of a fiber aggregate composed of short fibers. It may also be a sponge-like porous material having a large number of pores, such as a sponge. That is, any structure may be used as long as it is made of a porous material (having a large number of voids to the extent that water can be sucked up by capillary action). Further, for example, the first sound absorbing material may be composed of a fiber assembly made up of short fibers, and the second sound absorbing material may be composed of a fiber assembly made up of long fibers, and their combination is free. Alternatively, only one sound absorbing material may be provided as the sound absorbing member.

In the above-described embodiment, the holder 70 has a two-split structure consisting of the first and second shells 70A and 70B, but it does not necessarily have to be a two-split structure, and may be an integral structure.

INDUSTRIAL APPLICABILITY The present invention can be applied to an engine silencer, so it is extremely useful and has high industrial applicability.

2 Main silencer (silencer)
20 casing 28 bottom wall (bottom)
50 first exhaust lead-out pipe (exhaust lead-out pipe)
51c Pipe wall 53 Small hole 70 Holder 70A First shell 70B Second shell 71 Gap 72 Long axis 72a Lower end (one end side)
75A Joint flange 75B Joint flange 80 Water absorption hole 90 Sound absorbing member 91 First sound absorbing material 91a Long fiber 92 Second sound absorbing material 92a Long fiber

Claims (4)

a casing, an exhaust lead-out pipe formed with a plurality of small holes inside the casing for leading exhaust gas to the outside, and a portion of the pipe wall of the exhaust lead-out pipe in which the small holes are formed is defined as the pipe wall. A silencer for an engine, comprising: a holder covering from the outside with a gap between the
The holder has a flat cross-sectional shape with a long axis, and the long axis direction extends toward the bottom of the casing, and
A water absorption hole communicating between the inside and the outside of the holder is formed on one end side of the long axis of the holder ,
the axis of the holder is eccentric so as to be closer to the bottom of the casing than the axis of the exhaust lead-out pipe, or coincides with the axis of the exhaust lead-out pipe;
The porous material is composed of a fiber aggregate composed of long fibers,
The sound absorbing member is
a first sound absorbing material disposed on one end side of the long axis of the holder in the wall of the exhaust lead-out pipe;
A silencer for an engine, comprising: a pipe wall of the exhaust lead-out pipe and a second sound absorbing material arranged so as to wrap around the first sound absorbing material . a casing, an exhaust lead-out pipe formed with a plurality of small holes inside the casing for leading exhaust gas to the outside, and a portion of the pipe wall of the exhaust lead-out pipe in which the small holes are formed is defined as the pipe wall. A silencer for an engine, comprising: a holder covering from the outside with a gap between the
The holder has a flat cross-sectional shape with a long axis, and the long axis direction extends toward the bottom of the casing, and
A water absorption hole communicating between the inside and the outside of the holder is formed on one end side of the long axis of the holder ,
the axis of the holder is eccentric so as to be closer to the bottom of the casing than the axis of the exhaust lead-out pipe, or coincides with the axis of the exhaust lead-out pipe;
the bottom of the casing slopes downward to one side,
A muffler for an engine , wherein the longitudinal direction of the holder extends toward the one side of the bottom of the casing . In claim 1 or 2 ,
the holder comprises two semi-cylindrical shells joined with corresponding outwardly facing joining flanges, and
The joint flanges are provided on both end sides of the long axis,
A muffler for an engine, wherein the water absorption hole is formed between the joint flanges on one end side of the long shaft. In any one of claims 1 to 3 ,
A muffler for an engine, wherein a plurality of muffling exhaust pipes including the exhaust lead-out pipe are arranged in parallel in one direction within the casing.

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