JP3201068U - Route variable muffler - Google Patents

Abstract

A variable path muffler that can be miniaturized without sacrificing the silencing performance. A second route R2 is formed on the outer periphery of a first route R1 in which an inlet 101 for exhaust gas introduction and an outlet 201 for discharge are connected by an inner pipe 111, and the first route R1 is opened and closed. It can be so. The second path R2 includes an upstream gap UG (in communication with the inlet 101) that hermetically surrounds the outer peripheral surface of the inner pipe 111 with the upstream intermediate pipe 211a, and the outer peripheral surface of the inner pipe 111 with the downstream intermediate pipe 211b. The downstream gap DG that is hermetically enclosed (connected to the outlet 201) is connected to the outer peripheral gap OG that is formed by hermetically surrounding the outer peripheral surfaces of the upstream intermediate pipe 211a and the downstream intermediate pipe 211b with the outer pipe 251. The communication is made by slits 213 provided in the upstream intermediate pipe 211a and the downstream intermediate pipe 211b, respectively. [Selection] Figure 7

Description

  The present invention relates to a muffler that reduces the acoustic energy of exhaust gas guided from an exhaust pipe of an internal combustion engine and releases the exhaust gas to the outside, and in particular, a variable path muffler that can switch an exhaust gas route to a plurality of routes. About.

A muffler that reduces the acoustic energy of exhaust gas emitted from an internal combustion engine, for example, an automobile engine, and releases the exhaust gas to the outside has been put into practical use so that the exhaust gas path can be switched to a plurality of paths. Yes.
The purpose of switching the exhaust gas path in this way is to adjust the trade-off relationship between the exhaust efficiency and the silencing effect.
In other words, in order to improve the exhaust efficiency, it is necessary to reduce the exhaust resistance in the exhaust system to reduce the back pressure, but in that case, the silencing effect must be sacrificed. On the other hand, if the noise reduction effect is improved, the exhaust resistance is inevitably increased, and the exhaust efficiency is suddenly lowered. The exhaust efficiency and the silencing effect are in a trade-off relationship.
Therefore, a route that prioritizes exhaust efficiency and a route that prioritizes the silencing effect are prepared in advance so that a result that meets different purposes can be obtained depending on the route so that the exhaust gas route can be switched. The above-described variable path muffler.

Generally, when the engine maintains a low speed rotation, the back pressure becomes smaller than when the engine rotates at a high speed. For this reason, even if priority is given to the silencing effect, there will be no problem. On the other hand, it is desirable to give priority to the exhaust efficiency because the back pressure increases during high-speed rotation.
Therefore, as described in Patent Documents 1 and 3 to be described later, the exhaust gas path is selected so as to prioritize the silencing effect when the engine rotates at a low speed, and the exhaust gas path is selected so as to prioritize the exhaust efficiency when the engine rotates at a high speed. The route is switched.
As a switching method, Patent Document 1 discloses mechanical control according to the engine speed (see paragraphs [0023] to [0027]), and Patent Document 3 discloses electrical control using an actuator. (See paragraphs [0017] to [0019]).

In some cases, the route of the exhaust gas is switched according to the traveling purpose of the vehicle equipped with the engine. For example, users who enjoy sports running and competitions on a circuit want to run with priority on the noise reduction effect on general public roads, but want to enjoy the engine response and exhaust sound by switching to a route that prioritizes efficiency on the circuit. Is common.
Although not explicitly stated, it is considered that the invention described in Patent Document 2 described later is intended to switch the route of the exhaust gas according to the traveling purpose of the vehicle (paragraphs [0004] to [0006]. ], [0030] to [0033]).
In the invention described in Patent Document 2 as well, as in Patent Document 3, the exhaust gas path is switched by electrical control using an actuator (see paragraph [0027]).

As described above, a muffler that can switch an exhaust gas route to a plurality of routes has been widely known and put into practical use.
Next, a structure for switching the exhaust gas path to a plurality of paths will be described.

First, Patent Document 1 discloses a so-called box-shaped muffler.
The present invention divides the inside of the outer shell (1) of the muffler into a plurality of chambers (3, 4, 5), an inlet pipe (8) on the engine side, an outlet pipe (9) communicating with the outside, and a plurality of The inner pipe (6, 7) is passed through each room, and the butterfly valve (10) is attached to one of the inner pipes so as to be freely opened and closed (paragraphs [0014] to [0015], [0017] to [0022], (See FIG. 1). The butterfly valve is closed during low-speed engine rotation with low exhaust gas dynamic pressure, and is configured to open as the rotational speed increases and exhaust gas dynamic pressure increases (paragraphs [0023] to [0027]. reference).
Therefore, if the plurality of rooms (3, 4, 5) are called the first room (5), the second room (4), and the third room (3) from the engine side, they are introduced from the inlet pipe. Exhaust gas is discharged from the outlet pipe through the first chamber (5) from the second chamber (4) during low-speed rotation of the engine with the butterfly valve closed, while the butterfly valve is open At the time of high-speed rotation, in addition to the path, it is discharged from the outlet pipe through the third room (3) through the first room (5). That is, the exhaust gas passes only through the first and second rooms when the engine rotates at a low speed, and passes through all of the first to third rooms when the engine rotates at a medium and high speed.
Therefore, a high noise reduction effect is obtained during low-speed engine rotation, and exhaust efficiency improves as the engine shifts to medium-high speed rotation (see paragraph [0054]).

Next, Patent Document 2 discloses a path variable muffler that is further downsized.
In other words, this muffler covers the periphery of a pipe having an intake port (14) for introducing exhaust gas and an exhaust port (16) for exhausting with a jacket (18), and the inside of the pipe is a central conduit (22). The three pipes (26, 28, 30) forming the outer pipe (20) are arranged between the pipe and the jacket. The pipe line (26) communicates with the central pipe line on the inlet side, and the pipe line (30) communicates with the central pipe line on the exhaust port side. In the central pipeline, a butterfly valve (24) is provided on the exhaust side of the connecting position of the pipeline (26) (see paragraphs [0022] to [0025], FIG. 3, FIG. 3). 4, FIG. 7, FIG. 8).
Therefore, when the butterfly valve is opened, most of the exhaust gas introduced from the intake port passes through the central conduit (22) to the exhaust port. At this time, the back pressure is lowered, while the silencing effect is minimized (see paragraphs [0029] to [0030], FIG. 7).
When the butterfly valve is slightly opened, the exhaust gas introduced from the intake port proceeds to the exhaust port through three conduits (26, 28, 30), that is, the outer peripheral conduit (20). Part of it also passes through the central conduit (22). At this time, the back pressure becomes an intermediate level, and the silencing effect is enhanced (see paragraphs [0031] to [0032], FIG. 8).
When the butterfly valve is completely closed, the exhaust gas introduced from the intake port passes through only the outer peripheral pipe line (20) and proceeds to the exhaust port. At this time, the back pressure and the silencing effect are maximized (see paragraph [0033]).

Patent Document 3 discloses a variable path muffler having a smaller and simplified configuration.
That is, this muffler has a double pipe structure in which an inner pipe (30) is housed inside an outer pipe (20) that introduces exhaust gas and exhausts, and an open / close valve (40) is provided at the end of the inner pipe. (See paragraphs [0014] to [0015], FIG. 1).
In this document, the inside of the inner pipe is called a first path (R1), and the gap between the outer pipe and the inner pipe is called a second path (R2). The second passage (R2) has a larger fluid cross-sectional area than the first passage (R1) (see paragraph [0016]).
Therefore, according to the open / close state of the open / close valve, the exhaust gas path is variable in three ways: only the first path (R1), only the first path (R1) and the second path (R2), and only the second path (R2). can do.
When the engine speed is low as in idling, a sufficient silencing effect can be obtained by setting the exhaust gas path only to the first path (R1) (see paragraph [0021]).
When the engine speed is medium as in normal driving, a sufficient silencing effect can be obtained by using only the second path (R2) as the exhaust gas path (see paragraph [0022]).
When the engine speed is high, such as during acceleration travel, the exhaust gas path is both the first path (R1) and the second path (R2), thereby reducing the exhaust resistance and reducing the back. The pressure increase can be prevented and the engine performance can be improved (see paragraph [0024]).

JP 09-303143 A Japanese translation of PCT publication 2010-500496 JP 20012344741 A

Miniaturization of the variable path muffler is becoming more important.
In particular, in the field of ordinary passenger cars, the installation space for the variable path muffler is gradually becoming narrower due to the recent trend of adjusting the airflow in the lower part of the vehicle body from the viewpoint of aerodynamics.
For this reason, in the so-called box-type variable path muffler disclosed in Patent Document 1, it is actually difficult to secure the installation space.

  In this respect, the variable path muffler having the structure described in Patent Documents 2 and 3 is relatively small, and in terms of securing an installation space, it is at least as compared with the box-shaped one described in Patent Document 1. The advantage is recognized.

  However, the variable path muffler described in Patent Document 2 has a structure in which three pipes (26, 28, 30) are accommodated between the pipe constituting the central pipe (22) and the jacket (18). There is a problem that the pipe line restricts the miniaturization of the entire muffler.

On the other hand, the variable path muffler described in Patent Document 3 has a double pipe structure in which the inner pipe (30) is housed in the outer pipe (20). Further downsizing is possible.
However, the variable path muffler described in Patent Document 3 has doubts about the degree of the silencing effect.
If a great silencing effect is to be obtained, the axial lengths of the outer pipe (20) and the inner pipe (30) will have to be increased, and even if the length is increased to some extent, it is impossible to obtain a great silencing effect. It is thought that it is. Both the first path (R1) and the second path (R2) are formed in a substantially straight shape, and the exhaust gas path is not so narrow as compared with the variable path muffler described in Patent Documents 1 and 2. is there.
Regarding this point, it is clearly stated in Patent Document 3 itself that the use of a sub-muffler is planned, and the correctness of the assumption that the silencing effect is low is supported (see FIG. 1 of Patent Document 1). .
Therefore, the variable path muffler disclosed in Patent Document 3 cannot necessarily be reduced in size if sufficient noise reduction performance is to be obtained.

  The present invention has been made in view of these points, and an object thereof is to obtain a variable path muffler that can be miniaturized without sacrificing the silencing performance.

  A variable path muffler according to the present invention includes an inner pipe that connects an inlet that introduces exhaust gas and an outlet that discharges exhaust to form a first path, a valve that opens and closes an internal passage of the inner pipe, and an inner pipe The outer peripheral surface of the inlet side is hermetically enclosed, and an upstream intermediate pipe that forms an upstream gap communicating with the inlet between the outer peripheral surface and the outer peripheral surface of the inner pipe is sealed, and the outer peripheral surface of the outlet side of the inner pipe is sealed A downstream intermediate pipe that forms a downstream gap that communicates with the outlet, and an outer peripheral surface of the upstream intermediate pipe and the downstream intermediate pipe is hermetically enclosed. An outer pipe that forms an outer peripheral gap with the surrounding outer peripheral surface, and a first pipe that extends from the upstream gap to the downstream gap through the outer peripheral gap. Path to form a solved the above problems and the upstream intermediate pipe and the downstream intermediate pipe by the contact holes provided respectively.

  According to the present invention, the first path and the second path can be formed by the three-layer pipe structure of the inner pipe, the upstream intermediate pipe, the downstream intermediate pipe, and the outer pipe. Since the upstream clearance, outer peripheral clearance, and downstream clearance are communicated with each other through the communication hole, the exhaust gas path can be greatly narrowed. Therefore, both noise reduction performance and downsizing of the entire device are achieved at a high level. Can be made.

The perspective view which shows the path | route variable muffler of the state which removed the actuator as one Embodiment. The front view which shows the path | route variable muffler of the state which attached the actuator. It is a figure which shows the internal structure of a path | route variable muffler, (a) is a longitudinal front view of the state in which the valve was closed, (b) is a longitudinal front view of the state in which the valve was opened. The disassembled perspective view of a path | route variable muffler. The longitudinal cross-sectional front view of the path | route variable muffler shown without making only a slit pipe into a cross section. The exploded perspective view of a valve. It is a figure which shows the path | route of exhaust gas, (a) is a schematic diagram when a valve is closed, (b) is a schematic diagram when a valve is opened.

An embodiment will be described with reference to the drawings.
In the present embodiment, an example of the variable path muffler 1 is introduced. The variable path muffler 1 reduces the acoustic energy of exhaust gas guided from an exhaust pipe (not shown) of the internal combustion engine and releases it to the outside. The second route R2) can be formed (see FIGS. 7A and 7B).

As shown in FIG. 1, the variable path muffler 1 is formed in a cylindrical shape, has an inlet 101 for introducing exhaust gas at one end side, and has an outlet 201 for discharging exhaust gas at another end side. doing.
Although details will be described later, the variable path muffler 1 has a multilayer tube structure, and the outer pipe 251 disposed in the outermost layer also serves as an exterior case (see FIGS. 3A and 3B).
And the inlet 101 and the outlet 201 which are arrange | positioned at both ends have comprised the shape narrowed down to the small diameter. This shape is realized by the outer caps 252a and 252b fixed to both ends of the outer pipe 251 by welding.

The variable path muffler 1 incorporates a valve 301 (see FIGS. 3A, 3B, 6 and 7), which will be described later, and forms two paths of exhaust gas by opening and closing the valve 301. One system is a first path R1 passing through the central portion, and the other system is a second path R2 passing through the periphery.
Therefore, in order to control the opening and closing of the valve 301, the variable path muffler 1 has a drive portion 302 a (see FIG. 6) provided by extending one end side of the drive shaft 302, from a shaft hole (not shown) formed in the outer pipe 251 to the outside. It is protruding. The pedestal 252 is fixed to the outer pipe 251 by welding so as to cover the outer periphery of the shaft hole and the drive unit 302a.

As shown in FIG. 2, the variable path muffler 1 is provided with an actuator 351 for driving the valve 301.
The actuator 351 has a drive mechanism 353 attached to the frame 354 for driving the drive shaft 302 of the valve 301 in the rotational direction while reducing the suction force of the accumulator 352. The actuator 351 is routed by fixing the frame 354 to the base 252 by welding. The variable muffler 1 is attached.
Details of the actuator 351 will be described later.

The internal structure of the variable path muffler 1 will be described with reference to FIGS.
As shown in FIGS. 3A and 3B, the variable path muffler 1 has a four-layer tube structure of an inner pipe 111, a pair of intermediate pipes 211, a pair of partition pipes 231, and an outer pipe 251.
Of each of these pipes, the inner pipe 111 is formed by joining three pipes together. The upstream inner pipe 111a, the downstream inner pipe 111b, and the valve pipe 111c are three pipes, and the upstream inner pipe 111a and the downstream inner pipe 111b are fixed to both ends of the valve pipe 111c incorporating the valve 301 by welding. And seamed.
The pair of intermediate pipes 211 includes an upstream intermediate pipe 211a and a downstream intermediate pipe 211b.
The pair of partition pipes 231 includes an upstream partition pipe 231a and a downstream partition pipe 231b.
A pair of the above pipes, that is, the upstream inner pipe 111a and the downstream inner pipe 111b, the upstream intermediate pipe 211a and the downstream intermediate pipe 211b, and the upstream partition pipe 231a and the downstream partition pipe 231b are respectively The same thing is used, that is, the same shape, diameter, length, and thickness.

As shown in FIG. 4, the upstream inner pipe 111a, the upstream intermediate pipe 211a, and the upstream partition pipe 231a are nested, and are joined at one end of the valve pipe 111c and fixed by welding. Yes.
That is, the upstream inner pipe 111a has a straight shape whose diameter does not change in any part thereof, whereas the upstream intermediate pipe 211a is slightly larger in diameter than the upstream inner pipe 111a, and the upstream partition pipe 231a is slightly larger in diameter than the upstream intermediate pipe 211a. The upstream intermediate pipe 211a and the upstream partition pipe 231a are narrowed to substantially the same diameter as the upstream inner pipe 111a at one end side, and the narrowed portions are welded and fixed to each other.

Although not disassembled in FIG. 4, the downstream inner pipe 111b, the downstream intermediate pipe 211b, and the downstream partition pipe 231b have the same structure.
That is, the downstream inner pipe 111b, the downstream intermediate pipe 211b, and the downstream partition pipe 231b have a nested structure, and are joined to each other end of the valve pipe 111c and fixed by welding.
In this case, the downstream inner pipe 111b has a straight shape that does not change in diameter in any part thereof, whereas the downstream intermediate pipe 211b has a slightly larger diameter than the downstream inner pipe 111b. The partition pipe 231b has a slightly larger diameter than the downstream intermediate pipe 211b. The downstream intermediate pipe 211b and the downstream partition pipe 231b are narrowed to the same diameter as that of the downstream inner pipe 111b at one end, and the narrowed portions are fixed to each other by welding.

As shown in FIGS. 3A and 3B and FIG. 4, an inlet cap 212a is welded and fixed to the opening of the upstream intermediate pipe 211a, and an outlet cap 212b is fixed to the opening of the downstream intermediate pipe 211b. It is fixed by welding.
The inlet cap 212a is narrowed to the same diameter as the inner pipe 111 at the end opposite to the portion fixed to the upstream intermediate pipe 211a, and the inlet 101 is formed in this portion.
In the outlet cap 212b, the end opposite to the fixed portion with the downstream intermediate pipe 211b is narrowed to the same diameter as the inner pipe 111, and the outlet 201 is formed in this portion.

As shown in FIGS. 3A and 3B and FIG. 4, the pair of outer caps 252a and 252b described above is also squeezed to the same diameter as the inner pipe 111, and the inlet cap 212a and the outlet cap 212b are respectively. And is fixed by welding.
As described above, these outer caps 252a and 252b are fixed to the outer pipe 251. The outer pipe 251 can be opened at the portion of the cut 251a provided over the entire length in the axial direction. Therefore, when the outer pipe 251 covers a structure assembled by welding and fixing the inner pipe 111, the intermediate pipes 211a and 211b, the partition pipes 231a and 231b, and the outlet caps 212a and 212b, the outer pipe 251 is opened at the cut 251a.
This is necessary because the drive shaft 302 of the valve 301 built in the inner pipe 111 protrudes at the portion of the drive portion 302 a and protrudes from the diameter of the outer pipe 251.
Therefore, in the present embodiment, the outer pipe 251 is opened at the portion of the cut 251a, the shaft hole (not shown) provided in the outer pipe 251 and the pedestal 252 are passed through the drive unit 302a, and then the portion of the cut 251a is again formed. By joining, the structure is covered with the outer pipe 251 while avoiding interference with the drive shaft 302 of the valve 301. The outer pipe 251 is restored to its original shape by welding and fixing the cut portion 251a, and a pair of outer caps 252a and 252b are welded and fixed to both ends thereof. These outer caps 252a and 252b are also welded and fixed to a pair of caps 212a and 212b fixed to the pair of intermediate pipes 211.

Thus, the variable path muffler 1 is completed.
In the completed variable path muffler 1, the inner pipe 111 connects the inlet 101 for introducing exhaust gas and the outlet 201 for discharging to form a first path R1.
The upstream intermediate pipe 211a hermetically surrounds the outer peripheral surface on the inlet side of the inner pipe 111, and forms an upstream clearance UG that communicates with the inlet 101 between the outer peripheral surface and the surrounding outer peripheral surface.
The downstream intermediate pipe 211b hermetically surrounds the outer peripheral surface on the outlet side of the inner pipe 111, and forms a downstream gap DG communicating with the outlet 201 between the outer peripheral surface and the surrounding outer peripheral surface.
The outer pipe 251 hermetically surrounds the outer peripheral surfaces of the upstream intermediate pipe 211a and the downstream intermediate pipe 211b, and forms an outer peripheral clearance OG between the outer peripheral surfaces.
As shown in FIGS. 4 and 5, the upstream intermediate pipe 211a and the downstream intermediate pipe 211b are provided with a plurality of slits 213 serving as communication holes in the vicinity of the fixed portion with respect to the inner pipe 111. It has been. These slits 213 are arranged along the circumferential direction of the upstream intermediate pipe 211a and the downstream intermediate pipe 211b with the longitudinal direction thereof directed in the axial direction of the variable path muffler 1.
Accordingly, the plurality of slits 213 form a second path R2 from the upstream gap UG to the downstream gap DG via the outer circumferential gap OG.
In such a second path R2, the plurality of slits 213 are positioned in the vicinity of the portion where the upstream intermediate pipe 211a and the downstream intermediate pipe 211b are joined and fixed to the inner pipe 111. In both the gap UG and the downstream gap DG, they are arranged at positions closer to the back side than the center in the depth direction.

However, in the present embodiment, since the upstream partition pipe 231a and the downstream partition pipe 231b are provided, the second path R2 is formed in a more bent path.
That is, one end of the upstream partition pipe 231a is fixed to the inner pipe 111 so as to surround the plurality of slits 213 communicating with the upstream gap UG, and the other end is bonded and fixed between the upstream intermediate pipe 211a and the inlet cap 212a. Since it extends to the portion, a long folded region TB is formed on the upstream side of the second path R2.
The downstream partition pipe 231b has one end fixed to the inner pipe 111 so as to surround a plurality of slits 213 communicating with the downstream gap DG, and the other end is fixed to the downstream intermediate pipe 211b and the outlet cap 212b. Since it extends to the portion, a long folded region TB is formed on the downstream side of the second path R2.
Accordingly, the outer peripheral clearance OG includes the upstream outer peripheral clearance OG1 that has passed through the slit 213 communicating with the upstream clearance UG, the common outer peripheral clearance OG2 that has passed through this upstream outer peripheral clearance OG1, and the downstream side that has passed through this common outer peripheral clearance OG2. The outer circumferential gap OG3 is divided and folded.

The valve 301 will be described.
As shown in FIGS. 3A and 3B, the valve pipe 111c, which is a part of the inner pipe 111, has a valve seat 303 on the inner peripheral surface thereof. The valve seat 303 is formed so as to protrude over the entire inner peripheral surface of the valve pipe 111c at the axially central portion of the valve pipe 111c, that is, the axially central portion of the inner pipe 111.

As shown in FIGS. 3A and 3B and FIG. 6, the valve 301 has a drive shaft 302 passing through the valve pipe 111 c at the position of the valve seat 303. Since both ends of the drive shaft 302 are formed in a round bar shape, the drive shaft 302 is rotatable with respect to the valve pipe 111c.
One end side of the drive shaft 302 formed in a round bar shape is a drive portion 302a. As described above, this drive portion 302a also penetrates a shaft hole (not shown) and a base 252 provided in the outer pipe 251, It protrudes to the outside (see FIG. 1).
The drive shaft 302 has a flat plate-shaped fixed piece 302b between both end portions formed in a round bar shape, and a pair of valve plates 304 are fixed to the fixed piece 302b by screws 305. The valve plate 304 has a semicircular shape, and is fixed to one surface side and the back surface side of the fixed piece 302b. In this state, the valve plate 304 forms a perfect circle shape and size along the inner peripheral surface of the valve pipe 111c.
The fixed piece 302b is formed to have the same thickness as the valve seat 303. Therefore, when the valve 301 is closed, the pair of valve plates 304 are in close contact with the valve seat 303.

  Such a valve 301 is biased in one rotation direction by a biasing means (not shown) such as a spring, and is maintained in a state where the inner pipe 111 is closed. As an example, the urging means has a structure in which both ends of a coil spring (not shown) wound around a round bar-shaped portion of the drive shaft 302 are spanned between a fixed object such as the inner pipe 111 and the valve 301. Things can be used. Of course, the structure is not limited to such a structure, and various structures of urging means can be employed as long as the structure can urge the valve 301 in the closing direction.

The actuator 351 that drives the valve 301 will be described.
As shown in FIG. 2, the frame 354 fixed to the pedestal 252 provided in the outer pipe 251 is bent into an L shape, and the drive mechanism 353 is disposed on the surface fixed to the pedestal 252 and is bent at right angles to this surface. An accumulator 352 is attached to the surface.
The drive mechanism 353 has a drive piece 355 fixed to the end surface of the drive unit 302 a provided at one end of the drive shaft 302 of the valve 301 by welding, and the drive piece 355 and the accumulator 352 are connected by a connecting rod 356.
That is, the drive piece 355 has a shape obtained by rounding the three vertices of an isosceles triangle, and the vicinity of the center of gravity is fixed to the drive unit 302a. Therefore, the valve 301 is opened and closed by rotating the drive piece 355.
The rotational position of the drive piece 355 shown in FIG. 2 is the position when the valve 301 is closed. When the drive piece 355 is rotated counterclockwise in FIG. 2 from this state, the valve 301 is opened.
In FIG. 2, the drive mechanism 353 has one end of the connecting rod 356 rotatably connected to the vicinity of the vertex of the drive piece 355 that is raised to the left, and the other end of the connecting rod 356 is connected to the accumulator 352. Therefore, by pulling the connecting rod 356 into the accumulator 352, the drive shaft 302 of the valve 301 is rotated counterclockwise (in FIG. 2). As a result, the valve 301 is opened and the inner space of the inner pipe 111 is opened.

  Incidentally, the accumulator 352 includes a vacuum port 352a bent in an L shape on the side opposite to the connection side of the connecting rod 356, and a vacuum pump (not shown) is connected to the vacuum port 352a. The accumulator 352 is actuated by vacuum suction by the vacuum pump, and the connecting rod 356 is pulled inside.

  The frame 354 has pins 357 at positions that interfere with the rotation locus of the drive piece 355. The pin 357 regulates the amount of rotation of the driving piece 355 that rotates when the connecting rod 356 is pulled into the accumulator 352, and defines the opening of the valve 301.

In such a configuration, the variable path muffler 1 of the present embodiment can change the path of the exhaust gas according to the opening and closing of the valve 301.
Exhaust gas paths (first path R1, second path R2) will be described with reference to FIGS.

As shown in FIG. 7A, when the valve 301 is closed, the first path R1 (see FIG. 7A) is closed, and the exhaust gas path is only the second path R2.
In this case, the exhaust gas introduced from the inlet 101 enters the upstream clearance UG, passes through the slit 213 (of the upstream intermediate pipe 211a), and is guided to the outer peripheral clearance OG.
Here, the exhaust gas is folded back at the upstream outer circumferential gap OG1 to reach the common outer circumferential gap OG2, and is folded again at the downstream outer circumferential gap OG3 to enter the downstream gap DG from the slit 213 (of the downstream intermediate pipe 211b). It is discharged from the outlet 201.

As shown in FIG. 7B, when the valve 301 is opened, the first path R1 is opened, and the exhaust gas path is the first path R1 and the second path R2 (see FIG. 7A). ) However, since the first path R1 has a lower back pressure and a much lower exhaust resistance than the second path R2, most of the exhaust gas passes through the first path R1.
In this case, the exhaust gas path passing through the second path R2 is as described above, whereas in the first path R1, the exhaust gas introduced from the inlet 101 passes straight through the inner pipe 111. It is discharged from the outlet 201.

A comparison is made between when the exhaust gas passes through the first path R1 and when it passes through the second path R2.
Since the first path R1 is a straight-shaped path in which a space corresponding to the diameter of the inner pipe 111 is secured, it can be said that the first path R1 is a path with relatively low exhaust resistance.
Therefore, compared with the second route R2, the exhaust efficiency is significantly improved, but the noise reduction effect is inferior.
On the other hand, the second path R2 includes the upstream clearance UG, the slit 213 of the upstream intermediate pipe 211a, the outer peripheral clearance OG (upstream outer peripheral clearance OG1, common outer peripheral clearance OG2, downstream outer peripheral clearance OG3), and downstream intermediate. Since a narrow and long path such as the slit 213 of the pipe 211b and the downstream gap DG is formed, a great silencing effect can be obtained. The exhaust efficiency decreases accordingly.
Therefore, compared with the first path R1, the noise reduction effect is excellent, but the exhaust efficiency is reduced.

Accordingly, when traveling on a general public road, the valve 301 is closed and only the second route R2 is enabled. As a result, noise during exhaust gas discharge can be reduced and the environment can be protected.
On the other hand, when enjoying sports running in a space such as a circuit, for example, the valve 301 is opened to enable the first route R1. As a result, the exhaust pressure is improved by reducing the back pressure, and the response of the engine can be improved. You can also enjoy the exhaust note according to individual engine characteristics.

The route variable muffler 1 of the present embodiment is excellent in that both the silencing performance and the miniaturization of the entire apparatus can be achieved at a high level.
That is, the variable path muffler 1 of the present embodiment includes an inner pipe 111, an intermediate pipe 211 (upstream intermediate pipe 211a, downstream intermediate pipe 211b), a partition pipe 231 (upstream partition pipe 231a, downstream partition pipe 231b), In addition, a four-layer tube structure with the outer pipe 251 is employed, thereby forming a first path R1 and a second path R2.
Therefore, the second path R2 advantageous for the silencing characteristic can be formed narrow and long, and a high silencing effect can be obtained.
Moreover, each pipe which makes a four-layer pipe structure plays a double role, respectively. That is, the inner pipe 111 not only contributes to the formation of the first path R1, but also contributes to the formation of the upstream gap UG and the downstream gap DG in the second path R2. Further, the intermediate pipe 211 not only contributes to the formation of the upstream gap UG and the downstream gap DG, but also contributes to the formation of the outer circumferential gap OG. Similarly, the partition pipe 231 not only contributes to the formation of the upstream outer peripheral gap OG1 and the downstream outer peripheral gap OG3, but also contributes to the formation of the common outer peripheral gap OG2. The outer pipe 251 not only contributes to the formation of the outer circumferential gap OG (upstream outer circumferential gap OG1, common outer circumferential gap OG2, downstream outer circumferential gap OG3), but also serves as an exterior case for the variable path muffler 1. Therefore, the entire apparatus can be reduced in size.

  As described above, according to the variable path muffler 1 of the present embodiment, both the silencing performance and the downsizing of the entire apparatus can be achieved at a high level.

The reason why the variable path muffler 1 of the present embodiment is excellent in the silencing effect is that it employs a four-layer pipe structure. However, depending on the vehicle type, displacement and the like on which the variable path muffler 1 is mounted, the partition pipe Even with a three-layer tube structure in which 231 is omitted, a sufficient silencing effect can be obtained.
That is, when the partition pipe 231 is eliminated, the inside of the outer peripheral gap OG becomes a single space without the folded region TB, but there may still be a sufficient silencing effect.

In the present embodiment, in the upstream gap UG and the downstream gap DG, a slit 213 as a communication hole is arranged closer to the back side than the center in the depth direction.
As a result, the distances between the upstream gap UG, the upstream outer circumference gap OG1, the downstream gap DG, and the downstream outer circumference gap OG3 can be ensured long, and the noise reduction effect can be further enhanced.

  In addition, since the communication hole for connecting the upstream gap UG and the downstream gap DG and the outer circumferential gap OG is the simple-shaped slit 213, the manufacture thereof is facilitated.

  Further, since a plurality of slits 213 are provided, the exhaust efficiency and the silencing characteristics can be freely set by adjusting the shape, size, number, arrangement pitch, and the like.

  In the present embodiment, since the inner pipe 111 is formed in a straight shape, the exhaust efficiency can be maximized in an environment where the first path R1 can be opened.

  Furthermore, in the present embodiment, the second path R2 is formed symmetrically around the axially middle part of the inner pipe 111, and the valve 301 is disposed in the axially middle part of the inner pipe 111. The structure of 1 can be simplified, and parts can be shared and manufacturing can be facilitated.

  In the embodiment described above, various modifications and changes are possible.

For example, by adjusting the length of the partition pipe 231, the length of the folded region TB formed in the outer circumferential gap OG can be freely set. In this case, only the folding region TB formed by the upstream partition pipe 231a may be varied, or only the folding region TB formed by the downstream partition pipe 231b may be varied.
In this way, by adjusting the length of one or both of the folded regions TB, it is possible to freely set the balance between the exhaust gas exhaust efficiency and the silencing characteristics in the second path R2.

Alternatively, either one or both of the partition pipes 231 may be omitted so that the folded region TB is not formed inside the outer peripheral gap OG.
In this case as well, it is possible to set a balance between the exhaust gas exhaust efficiency and the silencing characteristics in the second path R2.

The balance between the exhaust efficiency of the exhaust gas and the silencing characteristic in the second path R2 can also be implemented by changing the shape, number, size, and the like of the slits 213 as communication holes.
The change of the shape of the slit 213 may be performed by changing the shape of each slit 213 itself, or by changing the angle of the slit 213 to change the longitudinal direction thereof.

In this embodiment, a vacuum suction type drive source is used as a drive source of the actuator 351 for opening and closing the valve 301. However, the present invention is not limited to this, and any drive source can be used.
For example, an actuator that operates with electric force may be used, or a hydraulic drive mechanism may be used.

  The modifications and changes described above are merely examples, and various changes and modifications can be made in implementation.

101 ... Inlet 111 ... Inner pipe 201 ... Outlet 211a ... Upstream intermediate pipe 211b ... Downstream intermediate pipe 212 ... Slit (connection hole)
231a ... Upstream partition pipe 231b ... Downstream partition pipe 251 ... Outer pipe 301 ... Valve UG ... Upstream gap DG ... Downstream gap OG ... Outer peripheral gap R1 ... 1st path | route R2 ... 2nd path | route TB ... Folding area | region

Claims (8)

An inner pipe that connects an inlet for introducing exhaust gas and an outlet for discharging to form a first path;
A valve for opening and closing the internal passage of the inner pipe;
An upstream intermediate pipe that hermetically surrounds the outer peripheral surface on the inlet side of the inner pipe, and forms an upstream clearance communicating with the inlet between the outer peripheral surface and the surrounding outer peripheral surface;
A downstream intermediate pipe that hermetically surrounds the outer peripheral surface on the outlet side of the inner pipe, and forms a downstream gap communicating with the outlet between the outer peripheral surface and the surrounding outer peripheral surface;
An outer pipe that hermetically encloses the outer peripheral surfaces of the upstream intermediate pipe and the downstream intermediate pipe, and forms an outer peripheral gap between the outer peripheral surface and the outer peripheral surface;
A communication hole provided in each of the upstream intermediate pipe and the downstream intermediate pipe so as to form a second path from the upstream gap to the downstream gap via the outer peripheral gap,
A variable path muffler characterized by comprising: An upstream partition pipe that surrounds the communication hole communicating with the upstream clearance inside the outer peripheral clearance and forms a folded region on the upstream side of the second path;
The variable path muffler according to claim 1. A downstream partition pipe that surrounds the communication hole communicating with the downstream clearance inside the outer peripheral clearance and forms a folded region downstream of the second path;
The variable path muffler according to claim 1, wherein the variable path muffler is provided. In either one or both of the upstream gap and the downstream gap, the communication hole is arranged closer to the back side than the center in the depth direction,
4. The variable path muffler according to claim 1, wherein the muffler is a variable path muffler. The communication hole is a plurality of slits arranged along the circumferential direction of one or both of the upstream intermediate pipe and the downstream intermediate pipe.
The variable path muffler according to claim 1, wherein the variable path muffler is provided. The inner pipe has a straight shape,
The variable path muffler according to claim 1, wherein the muffler is a variable path muffler. The second path is formed symmetrically around the center part in the axial direction of the inner pipe.
The variable path muffler according to claim 1, wherein the muffler is a variable path muffler. The valve is disposed in an axially middle part of the inner pipe,
The variable path muffler according to claim 7.

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