JP7005866B2 - Exhaust noise reduction device - Google Patents

Description

The present invention relates to an exhaust noise reducing device.

The following Patent Document 1 discloses a noise muffling device in which a speaker is provided in the vicinity of an engine muffler of a construction machine, and a sound having a phase opposite to that of the exhaust gas discharged from the engine muffler is emitted from the speaker to reduce the noise. Has been done.

Japanese Unexamined Patent Publication No. 2010-24876

However, since the noise muffling device of Patent Document 1 is a precision device, maintenance is not easy.

In consideration of the above facts, an object of the present invention is to provide an exhaust noise reducing device that can reduce the exhaust noise generated at the exhaust port of the muffler and is easy to maintain.

The exhaust noise reducing device according to claim 1 is connected to the waveguide attached to the exhaust port of a muffler that reduces the noise generated by the exhaust gas discharged from the internal combustion engine, and is generated at the exhaust port. It has a silencer that reduces exhaust noise, and the silencer surrounds the silencer pipe connected to the waveguide, the branch pipe connected to the silencer pipe, and the silencer pipe and the branch pipe. , A cylinder having a space for exhausting exhaust sound from the branch pipe, and a partition plate arranged in a direction orthogonal to the axial direction of the muffling pipe and partitioning the space in a direction orthogonal to the axial direction of the muffling pipe. And, the branch pipe is provided in each of the spaces partitioned by the partition plate, and the volume of the space partitioned by the partition plate is the same, and the volume of the space partitioned by the partition plate is the same. The inner diameter is smaller than the inner diameter of the other branch pipe.

The exhaust noise reducing device according to claim 1 is a means for reducing exhaust noise of an exhaust noise reducing device at a construction site where noise countermeasures are required, for example, without replacing the muffler of a heavy construction machine having insufficient noise countermeasures with a soundproof muffler. The exhaust noise generated at the exhaust port of the muffler can be reduced simply by attaching it to the exhaust port of the muffler.

Further, since the exhaust noise reducing means is attached to the exhaust port of the muffler, it can be appropriately replaced according to the frequency of the sound source and the required exhaust noise reducing effect. Therefore, various exhaust sounds can be reduced without using precision equipment. Therefore, maintenance of the exhaust noise reducing means is easy.

Further, for example, in the conventional technique of emitting a sound having a phase opposite to that of the exhaust sound from the speaker to reduce the exhaust sound, a power supply is required and the exhaust sound may be amplified if the phase of the sound emitted from the speaker is out of phase. On the other hand, the exhaust noise reducing device according to claim 1 does not require a power source, and there is no risk of amplifying the exhaust noise.

Further, in the exhaust noise reducing device of claim 1 , the exhaust noise reducing means connects a silencer that reduces the captured exhaust noise, the silencer and the exhaust port, and guides the exhaust noise to the silencer. It has a wave tube and.

The exhaust noise reducing device according to claim 1 is configured by connecting an exhaust port and a silencer with a waveguide. Therefore, there are no restrictions on the installation location of the silencer as compared with the configuration in which the silencer is directly connected to the exhaust port.

The exhaust noise reducing device according to claim 2 is the exhaust noise reducing device according to claim 1, wherein an adjusting pipe whose length can be adjusted is fixed to the branch pipe.
The exhaust noise reducing device according to claim 3 is the exhaust noise reducing device according to claim 1 or 2 , wherein the space is filled with glass wool.
In another aspect of the exhaust noise reducing device, the silencer surrounds a silencer tube to which the waveguide is connected and a through hole is formed in the tube wall, and the silencer tube, and exhaust sound is discharged from the through hole. It has a tubular body provided with a space and a sound absorbing material filled in the space.

According to another aspect of the exhaust noise reducing device, the exhaust noise is emitted into the space of the cylinder through the through hole of the muffling pipe. Since this space is filled with a sound absorbing material, the effect of reducing exhaust noise can be enhanced.

The exhaust noise reducing device according to the present invention can reduce the exhaust noise generated at the exhaust port of the muffler and is easy to maintain.

(A) is a side view showing a state in which the exhaust noise reduction device according to the first embodiment of the present invention is attached to the exhaust port of a muffler of a heavy construction machine, and (B) is a rear view. It is sectional drawing which shows the exhaust noise reduction apparatus which concerns on 1st Embodiment of this invention, (A) is the sectional drawing in the direction along the exhaust flow path, (B) is exhaust shown by line BB of (A). It is sectional drawing in the direction orthogonal to the flow path. It is sectional drawing which shows the exhaust noise reduction apparatus which concerns on 2nd Embodiment of this invention, (A) is the sectional drawing in the direction along the exhaust flow path, (B) is exhaust shown by line BB of (A). It is sectional drawing in the direction orthogonal to the flow path. (A) is a table showing the exhaust sound reducing effect of the sound absorbing muffler and the resonance muffler, and (B) is a graph plotting the values shown in the table of (A).

[First Embodiment]
As shown in FIGS. 1A and 1B, the exhaust noise reducing device 20 of the first embodiment is a muffler 16 that reduces the noise generated by the exhaust gas emitted from the internal combustion engine (engine) 14 of the heavy construction machine 12. It is detachably attached to the exhaust port 18. Although the hydraulic excavator is shown as an example of the heavy construction machine 12 in FIGS. 1A and 1B, the exhaust noise reducing device 20 is a heavy construction machine such as a crane, a bulldozer, a dump truck, a pile driving machine, or gasoline. It can be mounted on machines equipped with various internal combustion engines such as engines and gas turbines.

(Exhaust noise reduction device)
As shown in FIG. 2A, the exhaust noise reducing device 20 includes a silencer 30 that reduces the captured exhaust noise, and an exhaust of a muffler 16 (see FIG. 1) mounted on the silencer 30 and the heavy construction machine 12. It is provided with a waveguide 40 that connects to the mouth 18 and transmits exhaust sound to the muffler 30, and a discharge pipe 60 that is connected to the downstream side of the exhaust flow path of the muffler 30 and discharges exhaust to the outside. The silencer 30 and the waveguide 40 are examples of the exhaust noise reducing means in the present invention.

(Silencer)
The silencer 30 includes a sound deadening tube 32 to which the waveguide 40 is connected, and a cover 34 that surrounds the sound deadening tube 32 and forms a sound absorbing space 34A between the sound deadening tube 32. As shown in FIGS. 1A and 1B, the silencer 30 is installed on the upper part of the vehicle body of the heavy construction machine 12 by using a metal jig 31. The jig 31 includes a holding portion for holding the silencer 30, and a leg portion fixed to the vehicle body of the heavy construction machine 12, and the leg portion is a magnet, a bolt, an adhesive, and an adhesive sheet on the vehicle body of the heavy construction machine 12. It is fixed using such as.

The sound deadening pipe 32 is formed by bending a heat-resistant steel plate into a cylindrical shape, and through holes 32C are regularly arranged in the pipe wall. The through hole 32C communicates the internal space 32A of the sound deadening tube 32 with the sound absorbing space 34A. In this embodiment, SUH409 is used as the heat-resistant steel used for the muffling tube 32, but ferrite-based heat-resistant steel such as SUH21 and SUH409L, and austenitic heat-resistant steel such as SUH309 and SUH660 may be used. By using these heat-resistant steels, durability against high-temperature exhaust is ensured.

The cover 34 has a tubular portion 36 formed by bending a steel plate into an elliptical cylinder, and a pair of lid portions 38 joined to both end portions 36A of the tubular portion 36 to close the sound absorbing space 34A. , Is equipped. The end portion 38A of the lid portion 38 is fitted into the end portion 36A of the tubular portion 36. Further, a mounting hole 38B is formed in the lid portion 38, and a muffling tube 32 is fitted in the mounting hole 38B. Although SUS304 is used as the steel plate used for the tubular portion 36 and the lid portion 38 in the present embodiment, it may be used as a heat-resistant steel plate (SUH409) in the same manner as the sound deadening pipe 32.

As shown in FIG. 2B, the center O1 of the sound deadening tube 32 and the center O2 of the cover 34 are arranged so as to be offset from each other, and the cover 34 is arranged along the radial direction of the sound deadening tube 32 from the center O1 of the sound deadening tube 32. The distance L from the outer peripheral surface of the muffling tube 32 to the inner peripheral surface of the cover 34 on the straight line drawn toward the inner peripheral surface is non-uniform in the circumferential direction of the muffling tube 32 (for example, FIG. 2 (FIG. 2). L1 and L2) shown in B).

The sound absorbing space 34A formed between the sound deadening tube 32 and the cover 34 is filled with glass wool 90 as a sound absorbing material. The density of the glass wool 90 can be appropriately set depending on the required sound absorbing effect, but in general, the higher the density, the higher the sound absorbing effect tends to be. In addition to glass wool 90, rock wool, SUS wool and the like can be used as the sound absorbing material. The exhaust sound reducing device 20 of the first embodiment is a sound absorbing muffler that absorbs and reduces exhaust sound by using such a sound absorbing material.

Further, in the exhaust noise reducing device 20, when the exhaust gas flows from the waveguide 40 to the muffling tube 32, the flow path area is expanded from the cross-sectional area of the waveguide 40 to the cross-sectional area of the cover 34. Therefore, the speed and pressure of the exhaust gas are reduced, and the exhaust sound is reflected on the inner peripheral surface of the cover 34, so that the exhaust sound in the low frequency band is reduced. In this way, the exhaust noise reducing device 20 also acts as an extended muffler.

(Waveguide)
The waveguide 40 is connected to the sound deadening tube 32 of the silencer 30, and is formed of a flexible duct made of aluminum that can be curved with a certain range of curvature, and a muffler in the waveguide 42 and the heavy construction machine 12. A joint portion 44 for connecting and fixing the exhaust port 18 of 16 (see FIGS. 1A and 1B) is provided. The length of the waveguide 42 can be freely set, and the silencer 30 can be arranged at an arbitrary position on the upper part of the vehicle body of the heavy construction machine 12 as shown in FIGS. 1A and 1B. It is not limited to the upper part of the vehicle body of the heavy construction machine 12, and can be placed in a place such as the ground surface GL where the heavy construction machine 12 is placed. As the material of the waveguide 42, a metal material such as a galvanized steel plate or SUS304 can be appropriately used.

One end 42B of the waveguide 42 is fitted into the end 32B of the sound deadening tube 32, and the other end 42A of the waveguide 42 is fitted into the end 44A of the joint 44. In the present embodiment, the waveguide 42 is assumed to have sufficient rigidity so as not to easily fall off while being fitted in the sound deadening tube 32 or the joint 44. However, when the waveguide 42 is made of a material that does not have such rigidity, the diameter of the waveguide 42 is set to be larger than the end 32B of the sound deadening tube 32 and the end 44A of the joint 44. , The outer peripheral surface side of the end portion 32B of the sound deadening pipe 32 and the end portion 44A of the joint portion 44 may be covered and fixed with, for example, a fastening band.

The waveguide 42 has a sufficient pipe diameter so as not to interfere with the performance of the heavy construction machine 12, the internal combustion engine 14, and the muffler 16 even if the exhaust gas passes through. Further, if the sound deadening pipe 32 can be connected to the exhaust port 18 of the muffler 16 (see FIG. 1) in the heavy construction machine 12, the waveguide 40 can be omitted. By omitting the waveguide 40, the configuration of the exhaust noise reducing device 20 can be simplified.

The joint portion 44 is configured by fitting the end portion 42A of the waveguide portion 42 into one end portion 44A and fitting the exhaust port 18 of the muffler 16 (see FIG. 1) in the construction heavy equipment 12 into the other end portion 44B. ing.

Since the joint portion 44 connects the waveguide 42 having a different pipe diameter and the exhaust port 18, the inner diameter is changed from substantially the same diameter as the outer diameter of the waveguide 42 to substantially the same diameter as the outer diameter of the exhaust port 18. It is provided with a diameter-expanding portion 44C that expands the diameter. If the outer shape of the waveguide 42 and the outer shape of the exhaust port 18 are the same, the enlarged diameter portion 44C can be omitted.

(Discharge pipe)
One end 60B of the discharge pipe 60 is fitted into the exhaust downstream end 32B (the end opposite to the side to which the waveguide 40 is connected) of the muffler 30 on the exhaust downstream side. Further, a substantially U-shaped curved portion 60C is formed from the end portion 60B to the other end portion 60A. Therefore, the exhaust gas and the exhaust sound that flowed in the direction indicated by the arrow M in FIG. 2 and passed through the muffling pipe 32 flow in the direction indicated by the arrow N opposite to the arrow M in the process of passing through the exhaust pipe 60. .. Therefore, the exhaust noise reducing device 20 can be configured more compactly than, for example, as compared with the case where the curved portion 60C is not formed in the discharge pipe 60.

(Action and effect)
According to the exhaust noise reduction device 20 of the first embodiment, if the silencer 30, the waveguide 40, and the exhaust pipe 60 are assembled in advance at the factory, for example, at a construction site, the joint portion 44 of the waveguide can be constructed as a heavy machine. The exhaust noise generated at the exhaust port can be reduced only by attaching the muffler 16 (see FIG. 1) to the exhaust port 18 of the muffler 16.

Further, as shown in FIG. 2B, from the outer peripheral surface of the muffling tube 32 on a straight line drawn from the center O1 of the muffling tube 32 toward the inner peripheral surface of the cover 34 along the radial direction of the muffling tube 32. The distance L to the inner peripheral surface of the cover 34 is non-uniform in the circumferential direction of the muffling tube 32. Therefore, the thickness of the glass wool 90 through which the exhaust sound discharged from the through hole 32C of the sound deadening pipe 32 to the sound absorbing space 34A reaches the inner peripheral surface of the cover 34 is the thickness in the circumferential direction of the sound deadening pipe 32. It becomes non-uniform.

When the glass wool is thick, the sound absorption effect in the low frequency band is higher than when the glass wool is thin. In the silencer 30, by arranging the center O1 of the silencer tube 32 and the center O2 of the cover 34 so as to be offset from each other, a portion where the thickness of the glass wool 90 is thicker than in the case where the center O1 and the center O2 coincide with each other is formed. It is provided to enhance the sound absorption effect in the low frequency band.

Further, as shown in FIG. 2A, by adding the exhaust pipe 60 to the exhaust downstream side of the muffling pipe 32, the resonance frequency of the entire exhaust sound reducing device 20 is lowered. As a result, the effect of reducing exhaust noise is exhibited even in the low frequency band. Therefore, the exhaust noise reducing device 20 can also obtain the exhaust noise reducing effect by the exhaust pipe 60.

Although the discharge pipe 60 is provided with a curved portion 60C in the present embodiment, the embodiment of the present invention is not limited to this. For example, the discharge pipe 60 may be configured as a straight pipe without providing the curved portion 60C. Exhaust noise can be reduced without providing the curved portion 60C.

Further, in the present embodiment, the discharge pipe 60 has a constant pipe diameter, that is, a flow path area, but the embodiment of the present invention is not limited to this. For example, the discharge pipe 60 may be provided with a diameter-expanded portion that increases the flow path area. By providing the enlarged diameter portion, the effect of reducing exhaust noise can be enhanced.

Further, although it is assumed that the discharge pipe 60 is fitted in the silencer 30 in the present embodiment, the embodiment of the present invention is not limited to this. For example, the silencer 30 and the waveguide 40 may be omitted, and the discharge pipe 60 may be directly connected to the exhaust port 18 of the muffler 16 (see FIG. 1) in the heavy construction machine 12. Even if the exhaust pipe 60 is directly connected to the exhaust port 18, the effect of reducing exhaust noise can be obtained. With respect to the discharge pipe 60 in this case, the presence or absence of the curved portion 60C can be appropriately selected. When the silencer 30 and the waveguide 40 are omitted, the exhaust pipe 60 is the exhaust noise reducing means in the present invention.

[Second Embodiment]
Next, the exhaust noise reduction device 22 according to the second embodiment of the present invention will be described. For the same configuration as that of the first embodiment, the same reference numerals are used, and the description thereof will be omitted. The exhaust noise reducing device 22 of the second embodiment has a resonance muffler that is detachably attached to the exhaust port 18 of the muffler 16 that reduces the noise generated by the exhaust gas emitted by the internal combustion engine (engine) 14 of the construction heavy machine 12. (See Fig. 1).

(Exhaust noise reduction device)
As shown in FIG. 3A, the exhaust noise reducing device 22 includes a silencer 70 that reduces the captured exhaust noise, and an exhaust port 18 of the muffler 16 (see FIG. 1) in the silencer 70 and the heavy construction machine 12. The waveguide 40 is connected to the silencer 70 to transmit the exhaust sound to the silencer 70, and the exhaust pipe 60 is connected to the silencer 70 to exhaust the exhaust gas. The silencer 70 and the waveguide 40 are examples of the exhaust noise reducing means in the present invention.

(Silencer)
The silencer 70 includes a sound deadening tube 72 to which the waveguide 40 is connected, and a cover 74 that surrounds the sound deadening tube 72 and forms resonance spaces 74A and 74B between the sound deadening tube 72. The resonance spaces 74A and 74B are partitioned from each other by a partition plate 75 arranged in a direction orthogonal to the axial direction of the muffling tube 72, and their respective volumes are formed to be substantially the same.

The sound deadening pipe 72 is formed in a cylindrical shape by bending a heat-resistant steel plate, and branch pipes 72A and 72B communicating the internal space 72C of the sound deadening pipe 72 and the resonance spaces 74A and 74B, respectively, project from the pipe wall. The inner diameters of the branch pipes 72A and 72B are smaller than the inner diameter of the muffling pipe 72, and the inner diameter of the branch pipe 72A is smaller than the inner diameter of the branch pipe 72B.

Adjustment pipes 80A and 80B can be attached to the branch pipes 72A and 72B. The inner diameters of the adjusting pipes 80A and 80B are substantially the same as the outer diameters of the branch pipes 72A and 72B, respectively, and the adjusting pipes 80A and 80B can be fixed at arbitrary positions in a state where the branch pipes 72A and 72B are fitted. The fixing method is not particularly limited, but for example, a through hole 82 having a female screw is formed in the adjusting pipes 80A and 80B, a bolt 84 is screwed into the through hole 82, and a branch pipe 72A at the tip of the bolt 84. By pressing the outer peripheral surface of 72B, the adjusting pipes 80A and 80B can be fixed to the branch pipes 72A and 72B. As described above, by using the adjusting pipes 80A and 80B, the lengths of the branch pipes 72A and 72B are variable. In order to adjust the fixed positions of the adjusting pipes 80A and 80B at the site where the exhaust noise reducing device 22 is installed, the lid portion 78 of the cover 74 is removed and the resonance spaces 74A and 74B are opened for work.

(Action and effect)
According to the exhaust noise reducing device 22 of the second embodiment, the silencer 70 constitutes the resonator 86A by the resonance space 74A and the branch pipe 72A. As a result, the exhaust sound having a frequency close to the natural frequency (resonance frequency) of the resonator 86A can be intensively reduced.

The resonance frequency f of the resonator 86A is proportional to the square root (√S) of the cross-sectional area S of the branch pipe 72A, and is the square root (√V) of the volume V of the resonance space 74A and the square root of the length L of the branch pipe 72A. It is inversely proportional to (√L). That is,
f∝√ (S / (VL)) ・ ・ ・ Equation (1)
Is established. At this time, if the length L of the branch pipe 72A becomes long, the resonance frequency f becomes small, and if the length L of the branch pipe 72A becomes short, the resonance frequency f becomes large.

In the exhaust sound reducing device 22 of the second embodiment, the length of the branch pipe 72A is made variable by the adjusting pipe 80A, and therefore the resonance frequency f of the resonator 86A can be changed. Therefore, by setting the resonance frequency f of the resonator 86A according to the frequency of the exhaust sound and resonating the resonator 86A, the exhaust sound can be efficiently reduced.

Further, the silencer 70 constitutes the resonator 86B by the resonance space 74B and the branch pipe 72B, similarly to the resonator 86A. Further, the branch pipe 72B has a variable length by the adjusting pipe 80B. Therefore, by adjusting the positions of the adjusting pipes 80A and 80B so that the resonator 86A and the resonator 86B resonate with the exhaust sound of frequencies close to each other, the effect of reducing the exhaust sound of a specific frequency can be enhanced. can. Alternatively, by adjusting the positions of the adjusting pipes 80A and 80B so that the resonator 86A and the resonator 86B resonate with the exhaust sound of different frequencies, the effect of reducing the exhaust sound in a wide frequency range can be obtained. can.

In the present embodiment, two resonance spaces (resonance spaces 74A and 74B) are provided inside the cover 74, but the embodiment of the present invention is not limited to this. For example, the internal space of the cover 74 may not be partitioned by the partition plate 75, and only one resonance space may be provided. In this case, since the volume V of the resonance space in the above equation (1) becomes large, the resonance frequency becomes small.

Alternatively, the number of partition plates 75 may be increased to form three or more resonance spaces, and each resonance space may be communicated with the internal space 72C of the muffling pipe 72 via a branch pipe. In this case, since the volume V of the resonance space in the above equation (1) becomes small, the resonance frequency becomes large.

Further, the size and number of resonance spaces can be appropriately selected, such as increasing the total length of the silencer 70 along the axial direction to form a plurality of resonance spaces having a large volume. In this way, by configuring a plurality of resonance spaces with an appropriate size, it is possible to effectively reduce the exhaust sound having a plurality of dominant frequencies. If the dominant frequency of the exhaust sound and the resonance frequency of the resonator match without the adjusting tube attached, the adjusting tube is not always necessary. Further, the inside of the resonance space may be filled with glass wool, rock wool or the like.

[performance test]
In order to demonstrate the exhaust noise reducing effect of the exhaust noise reducing devices 20 and 60 according to the embodiment of the present invention, the tests shown below were carried out.

In the test, first, the sound pressure level (dB) was measured by changing the rotation speed (rpm) of the engine of the rough terrain crane without installing the exhaust noise reducing device.
The engine speed for measuring the sound pressure level was 700 rpm during idling operation, 1800 rpm during medium speed rotation, and 2400 rpm during high speed rotation. The target frequency (Hz) for measuring the sound pressure level was the predominant frequency according to each engine speed. The predominant frequencies were a frequency of 31.5 Hz and a frequency of 63 Hz at a rotation speed of 700 rpm, a frequency of 80 Hz at a rotation speed of 1800 rpm, and a frequency of 80 Hz at a rotation speed of 2400 rpm.

Next, the exhaust noise reducing devices 20 and 60 were attached to the exhaust port of the muffler of the rough terrain crane, and the sound pressure level was measured by changing the engine speed. The engine speed and frequency for measuring the sound pressure level are the same as described above.

The table shown in FIG. 4A shows the sound pressure level when the exhaust noise reducing device is not attached to the exhaust port of the muffler of the rough terrain crane, and the exhaust noise reducing device 20 of the first embodiment at this exhaust port. The difference from the sound pressure level when the sound absorbing muffler, which is an example, is attached is described for each engine rotation speed and each frequency. Similarly, the sound pressure level when the exhaust noise reducing device is not attached to the exhaust port of the muffler of the rough terrain crane, and the case where the resonance muffler which is an example of the exhaust noise reducing device 22 of the second embodiment is attached to this exhaust port. The difference from the sound pressure level is described for each engine speed and frequency.

Further, in the graph shown in FIG. 4 (B), the values (sound pressure level difference) shown in the table of FIG. 4 (A) are plotted for each frequency.

According to FIGS. 4A and 4B, a sound absorbing muffler, which is an example of the exhaust noise reducing device 20 of the first embodiment, and an example of the exhaust noise reducing device 22 of the second embodiment are provided at the exhaust port of the muffler of the rough terrain crane. When any of the resonance mufflers is attached, the exhaust noise of 10 dB or more is reduced as compared with the case where the exhaust noise reducing device is not attached.

The sound pressure level of each frequency when the exhaust sound reduction device was not installed was 78.7 dB at a frequency of 31.5 Hz, 73.1 dB at a frequency of 63 Hz, 84.4 dB at a frequency of 80 Hz, and 87.2 dB at a frequency of 125 Hz. ..

That is, the sound pressure level at a frequency of 80 Hz was 84.4 dB when the exhaust sound reduction device was not installed, but by attaching the resonance muffler, the value shown in FIG. 4 (A) was reduced by 19.5 dB. It became 64.9 dB.

As described above, when the exhaust noise reducing devices 20 and 60 according to the embodiment of the present invention are attached to the exhaust port of the muffler, the exhaust noise is reduced as compared with the case where the exhaust noise reducing device is not attached.

14 Internal combustion engine 16 Muffler 18A Exhaust port 20, 22 Exhaust sound reduction device 30, 70 Silencer 32 Silencer tube 32C Through hole 34 Cover (cylinder body)
34A Sound absorption space (space)
40 Waveguide 90 Glass wool (sound absorbing material)

Claims (3)

A waveguide attached to the exhaust port of the muffler that reduces the noise generated by the exhaust gas emitted by the internal combustion engine.
It has a silencer that is connected to the waveguide and reduces the exhaust noise generated at the exhaust port.
The silencer is
A muffling tube connected to the waveguide and
The branch pipe connected to the muffling pipe and
A cylinder that surrounds the muffling pipe and the branch pipe and has a space for exhaust sound to be discharged from the branch pipe.
A partition plate arranged in a direction orthogonal to the axial direction of the muffling tube and partitioning the space in a direction orthogonal to the axial direction of the muffling tube.
Have,
The branch pipe is provided in each of the spaces partitioned by the partition plate, and the branch pipe is provided.
The volume of the space partitioned by the partition plate is the same, and the inner diameter of one branch pipe is smaller than the inner diameter of the other branch pipe.
Exhaust noise reduction device. An adjusting pipe whose length can be adjusted is fixed to the branch pipe.
The exhaust noise reducing device according to claim 1. The space is filled with glass wool,
The exhaust noise reducing device according to claim 1 or 2.

Images