JP2019035382A - Silencer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silencer equipped with an expansion chamber capable of effectively enhancing a silence characteristic near a specific frequency. A silencer 10 that silences noise propagating through a tube includes a rectangular parallelepiped expansion chamber 3, a first tube 1 connected to a substantially central portion of a first surface P1 of the chamber, It has the 2nd pipe | tube 2 connected to the approximate center part of the 2nd surface P2 of the chamber adjacent to the surface P1, and the 1st pipe | tube 1 side is connected and used for a noise source. The normal direction of the first surface 1 is the first direction X, the normal direction of the second surface 2 is the second direction Y, and the direction orthogonal to the first direction X and the second direction Y is the third direction Z. As described above, the partition wall 4 is erected so as to extend in the first direction X from the surface P3 facing the first surface P1 of the chamber 3. When viewed along the third direction Z, the partition wall 4 partitions the internal space of the chamber 3 into a U-shape. Further, the position of the partition wall 4 in the second direction Y substantially coincides with the position in the second direction Y of the center C1 of the connection portion of the first pipe 1. [Selection] Figure 1

Description

The present invention relates to a silencer that reduces noise propagating through a ventilation path. In particular, the present invention relates to a silencer comprising an expansion chamber provided in the ventilation path.

In an air intake system of an internal combustion engine for an automobile, an air conditioning system, a cooling air blowing system, or the like (so-called ventilation duct, ventilation duct, ventilation hose, etc.), noise caused by noise from the engine, fan, motor, etc. Since it propagates in the road and air column resonance occurs in the air duct, it has been desired to reduce noise for some time.

A technique of providing an expansion chamber as a silencer for noise propagating through the intake system and the ventilation path of the air duct is well known. Providing an expansion chamber in which the cross section of the ventilation path changes suddenly suppresses the propagation of noise due to the impedance change at the portion where the ventilation cross sectional area changes suddenly. However, with the extended chamber technology, it has been difficult to effectively mute noise in a specific frequency range.

In addition, a resonance silencer is known as a technique for silencing noise at a specific frequency in the ventilation path.
For example, Patent Document 1 discloses a resonance device for a Helmholtz resonator having a resonance chamber and a communication portion, and a resonance device in which a sound absorbing material is provided in the communication portion and the resonance chamber. Patent Document 2 discloses that a resonator is formed by providing an extended portion (resonance chamber) and a slit-like communication hole along a pipeline, and a sound absorbing material is provided in the resonance chamber.
According to these techniques, the noise absorbing effect is enhanced by the sound absorbing material while the noise of the specific frequency band is silenced by the resonator.

Japanese Patent Application Laid-Open No. 06-081737 JP 2009-250183 A

Each of these expansion chambers and resonant silencers requires a predetermined volume. In order to save the space of the silencer, there is a demand for a silencer that has both the silencer characteristic of the expansion chamber and the silencer characteristic of the resonance silencer. However, it has been difficult to realize the silencer.

An object of the present invention is to provide a silencer including an expansion chamber that can effectively enhance the silence characteristics near a specific frequency.

As a result of intensive studies, the inventor forms an expansion chamber type silencer by connecting two tubes to a specific position with respect to a rectangular parallelepiped expansion chamber, and further provides a partition wall having a specific form in the chamber. And it was found that the silencing characteristics near a specific frequency can be effectively improved, and the present invention has been completed.

The present invention is a silencer for silencing noise propagating through a tube, the silencer being a rectangular parallelepiped expansion chamber, a first tube connected to a substantially central portion of a first surface of the chamber, and the first A second tube connected to a substantially central portion of the second surface of the chamber adjacent to the first surface, the first tube side being connected to a noise source, and the normal direction of the first surface being The direction normal to the second surface is the second direction, the direction perpendicular to the first direction and the second direction is the third direction, and the first direction from the surface facing the first surface of the chamber The partition wall is erected so as to extend in the third direction, and when viewed in the third direction, the partition wall partitions the interior space of the chamber into a U-shape, and the second partition wall The silencer provided with the partition wall so that the position in the direction substantially coincides with the position in the second direction at the center of the connection portion of the first pipe It is (first invention).

In the first invention, preferably, the height of the partition wall measured along the first direction is 1/5 to 2/3 of the length of the chamber in the first direction (second invention).

According to the silencer of the present invention (the first invention), it is possible to effectively enhance the silencing characteristics in the vicinity of a specific frequency, even though the silencer includes an expansion chamber. In particular, when the height of the partition wall is set as in the second aspect of the invention, the silencing characteristic near a specific frequency is more effectively enhanced.

It is a perspective view which shows the silencer of 1st Embodiment. It is sectional drawing which shows the structure of the expansion chamber in 1st Embodiment. It is a figure which shows the silencing effect of the Example of the silencing apparatus of 1st Embodiment. It is a figure which shows the resonance mode of the 1st resonance frequency vicinity in an Example. It is a figure which shows the resonance mode of the 1st resonance frequency vicinity in a comparative example. It is a figure which shows the resonance mode of the 2nd resonance frequency vicinity in an Example. It is a figure which shows the resonance mode of the 2nd resonance frequency vicinity in a comparative example. It is a schematic diagram which shows the method of measuring an acoustic attenuation amount.

Embodiments of the present invention will be described below with reference to the drawings, taking as an example a silencer used in a part of an intake system that supplies air to an automobile engine. The invention is not limited to the individual embodiments shown below, and can be carried out by changing the form.
FIG. 1 is a perspective view showing a silencer 10 of the first embodiment. FIG. 2 is a cross-sectional view of the expansion chamber portion. The silencer 10 is configured by connecting two blower tubes (hereinafter also referred to as “tubes”) 1 and 2 to the expansion chamber 3. The internal space of the first tube 1, the internal space of the expansion chamber 3, and the internal space of the second tube 2 are sequentially connected to form a series of ventilation paths, and air flows therethrough. The silencer 10 has a cross-sectional area of the internal space that changes at the connection point between the tube and the chamber. As a result, the silencer 10 functions as a so-called extended chamber-type silencer so as to mute noise propagating in the tube.

In the above-described intake system, for example, the silencer 10 is connected to an end of the second pipe 2 with a duct member or the like on the inlet side, and is connected to an end of the first pipe 1 with a duct member or the like on the engine side. Used. The intake system may include other silencers, air cleaners, and the like. In addition to the intake system of an automobile internal combustion engine, the muffler 10 can be used for a ventilation path of an air conditioner, a ventilation path of an air cooling system such as a battery, and the like.

Tubes 1 and 2 are hollow tubes. The specific shape of the blast tubes 1 and 2 is determined according to various uses, and may be a straight tube shape, a curved shape, a bent shape, or the like as necessary. The blower pipes 1 and 2 may be rigid pipes or may be flexible hoses. The blower pipes 1 and 2 are preferably made of a non-breathable material, but part or all of the blower pipes 1 and 2 may be made of a breathable material. Further, a through hole (for example, a drain hole or a tuning hole) that allows the inside and outside of the pipe to communicate with each other may be provided in a part of the blast pipes 1 and 2.

The expansion chamber 3 provided in a hollow shape has a rectangular parallelepiped shape. In particular, a square shape is preferable when viewed from a direction orthogonal to the first tube 1 and the second tube 2. The internal space of the expansion chamber 3 does not have to be a strict rectangular parallelepiped, and may be provided with a corner R, a draft taper, a gradient, or the like. In addition, some of the surfaces constituting the rectangular parallelepiped chamber may be formed in a curved surface such as a cylindrical shape or a spherical shape. The internal space of the chamber may be a rectangular parallelepiped as a whole. The expansion chamber 3 may be formed with reinforcing ribs or beads. The material of the expansion chamber 3 is not particularly limited, but typically a non-breathable material, for example, a thermoplastic resin such as polypropylene resin is preferably used.

The first tube 1 is connected to a substantially central portion of the first surface P1 of the expansion chamber 3. The center line m1 of the first pipe 1 in the connecting portion does not have to exactly coincide with the center of the first surface P1, and even if they are separated from each other, the distance between them is one side of the first surface. It may be 20% or less of the length.

The 2nd pipe | tube 2 is connected to the approximate center part of the 2nd surface P2 of the expansion chamber 3 adjacent to the said 1st surface P1. The center line m2 of the second pipe 2 in the connecting portion does not have to exactly coincide with the center of the second surface P2, and even if they are separated from each other, the distance between them is one side of the second surface. It may be 20% or less of the length. In addition, in the rectangular parallelepiped chamber, the second surface P2 adjacent to the first surface P1 is “2” “3” when the first surface is a surface “1” in terms of a dice. It is one of the faces “4” and “5”.

In other words, the first pipe 1 and the second pipe 2 are attached to the chamber 3 so that the center lines m1 and m2 at the connecting portions of the pipes are substantially orthogonal to each other. The ventilation path when viewed as is bent at about 90 degrees in the expansion chamber 3 portion.

The silencer 10 is used with the first pipe 1 side connected to a noise source. That is, in the silencer 10 used in the intake system of an automobile engine, as described above, the first pipe 1 side is on the engine side that is a noise source, and the second pipe 2 side is on the inlet side. Connected. If the silencer 10 is used, for example, in a ventilation path of an air conditioner, the first pipe 1 side is connected to the fan or motor side that is a noise source.

The internal structure of the expansion chamber 3 will be described. 1 and 2, the normal direction of the first surface P1 of the chamber is the first direction X, the normal direction of the second surface P2 of the chamber is the second direction Y, and the first direction A direction orthogonal to X and the second direction Y is defined as a third direction Z. The center line m1 of the first tube 1 near the connecting portion and the first direction X are made parallel, and the center line m2 of the second tube 2 near the connecting portion and the second direction Y are made parallel. preferable.

Inside the expansion chamber 3, a partition wall 4 is erected so as to extend in the first direction X from a surface P3 facing the first surface P1 of the chamber. That is, the partition wall 4 is provided inside the chamber 3 so as to extend from the surface P3 toward the first pipe 1. Here, the surface P3 facing the first surface P1 is a surface of “6” when the first surface P1 is a surface of “1” in terms of a dice.

Further, the partition wall 4 is provided so as to straddle between the upper and lower side walls 3a and 3b of the chamber in the lower diagram of FIG. 2, and the right space of the chamber in the lower diagram of FIG. The front and back sides are partitioned in the depth direction. As a result, as shown in the upper diagram of FIG. 2, when viewed along the third direction Z, the partition wall 4 partitions the internal space of the chamber into a U shape with the right side opened.

The partition wall 4 is provided so that the position in the second direction of the partition wall 4 substantially coincides with the position in the second direction of the center C <b> 1 of the connection portion of the first pipe 1. In other words, the partition wall 4 is provided at a position substantially coinciding with the central axis m1 in the vicinity of the connection portion of the first tube 1. The position where the partition wall 4 is provided and the center C1 or the center axis m1 of the tube 1 do not have to coincide exactly, and even if the positions of both are separated, the distance is the length LY of the expansion chamber 3 in the second direction. Within 20%.

In the partition wall 4, the height H of the partition wall 4 measured along the first direction X is preferably 1/5 to 2/3 of the length LX in the first direction of the chamber 3. It is especially preferable that it is -1/2.

In addition to the partition wall 4, protrusions such as ribs and beads may be formed in the expansion chamber 3. In this case, the protrusions are formed so as not to hinder the action of the partition wall described later. It is preferable. On the other hand, the partition wall may serve as a rib or a bead.

The silencer 10 according to the first embodiment can be manufactured by using a known manufacturing technique, for example, injection molding or blow molding of a thermoplastic resin. The expansion chamber 3 may be manufactured by molding by blow molding or by welding an injection molded half crack. The blower tubes 1 and 2 may be formed by blow molding or the like. The connection between the expansion chamber 3 and the blower pipes 1 and 2 may be performed by a known connection structure or connection method. It is preferable that the connection portion between the expansion chamber 3 and the blower pipes 1 and 2 is appropriately sealed.

The operation and effect of the silencer 10 of the first embodiment will be described. The muffler 10 of the first embodiment has a muffler effect similar to that of a muffler provided with a normal expansion chamber in a relatively low frequency band (for example, a frequency band of 1000 Hz or less). Further, in a relatively high frequency band (for example, a frequency band of 1000 Hz to 2500 Hz), the silencer 10 is expanded at a specific frequency by providing the partition wall 4 with a specific form in the expansion chamber 3. A specific resonance mode appears in the space in the chamber, and the silencing characteristics near the specific frequency can be effectively enhanced.

The above effect will be described using an acoustic analysis simulation result in comparison with Examples and Comparative Examples.

(Example)
As an example corresponding to the above embodiment, an acoustic model of a silencer having the following specifications was created.
First pipe 1: straight pipe having a diameter of 60 mm and a length of 230 mm Second pipe 2: straight pipe expansion chamber 3 having a diameter of 60 mm and a length of 250 mm: first direction length LX = 98 mm, second direction length LY = 100 mm, third direction length LZ = 80 mm, with respect to the chamber, the first tube 1 is connected to the center of the first surface P1, and the second tube 2 is connected to the center of the second surface P2. .
The partition wall 4 is installed at a height H = 33 mm at a position coinciding with the center C1 of the first pipe 1 at the position in the second direction.

(Comparative example)
As a comparison object, an acoustic model of a silencer that differs in that the partition wall 4 is not provided in the expansion chamber 3 was created, and this was used as a comparative example.

An acoustic analysis was performed on the examples and comparative examples to determine the amount of sound attenuation, and the silencing effect was examined. As shown in FIG. 8, the sound attenuation amount is assumed that the noise source side end (end of the first pipe) β of the silencer to be examined is connected to the speaker device 99 that performs acoustic excitation. A simulation model for performing acoustic excitation is created, and the sound pressure Pα (the sound pressure measured at position α) and the sound source side (first It is an index for measuring the sound pressure Pβ (sound pressure measured at the position β) of the pipe end portion β) and taking the ratio (Pβ / Pα) between them to evaluate the silencing effect. A large acoustic attenuation value indicates that the silencing effect is large, and a small acoustic attenuation value indicates that the silencing effect is small. The acoustic simulation was performed by a finite element method (FEM method).

FIG. 3 shows the simulation results of the sound attenuation amounts of the example and the comparative example. In a region where the frequency is relatively low up to about 1000 Hz, the example and the comparative example show substantially the same acoustic attenuation amount (Attenuation in FIG. 3). In these frequency regions, it can be seen that the same silencing effect as that of the silencer provided with the conventional expansion chamber is exhibited.

In the silencer of the example, compared with the comparative example, an increase in the amount of acoustic attenuation is observed with peaks at 1335 Hz (first resonance frequency f1) and 2355 Hz (second resonance frequency f2). That is, in the frequency band near the first resonance frequency f1 (1200 Hz to 1450 Hz) and the frequency band near the second resonance frequency f2 (2000 Hz to 2400 Hz), the sound attenuation amount of the silencer of the embodiment is higher than that of the comparative example. It has become.

FIG. 4 shows the sound pressure distribution (resonance mode) in the expansion chamber around the first resonance frequency f1 (1335 Hz), and FIG. 5 shows the comparative example. These sound pressure distributions are sound pressure distribution diagrams in a cross section passing through the center of the tube as viewed from the third direction Z.

In the comparative example shown in FIG. 5, the sound pressure is high in the lower right space of the expansion chamber so that air moves and vibrates in the upward diagonal direction in the expansion chamber, and as it goes toward the upper left of the expansion chamber. A resonance mode of air is observed such that the sound pressure decreases. Due to the relationship between this resonance mode and the arrangement of the connection portions of the first tube and the second tube, in the comparative example, the sound pressure at substantially the same level as that generated in the first tube is the second tube. This also occurs, resulting in a decrease in sound attenuation.

On the other hand, in the embodiment shown in FIG. 4, the partition wall 4 is provided in the expansion chamber 3 as follows. That is, when viewed along the third direction Z, the partition wall 4 divides the internal space of the chamber into a U-shape, and the position of the partition wall 4 in the second direction Y is the first direction. A partition wall is provided so as to substantially coincide with the position in the second direction of the center C1 of the connection portion of the tube 1 (the partition wall 4 is substantially aligned with the central axis m1 in the vicinity of the connection portion of the first tube 1). Provided at the matching position). For this reason, the resonance mode at the first resonance frequency f1 changes. That is, in the expansion chamber of the embodiment, a resonance mode is observed in which the sound pressure is high in the lower right space separated by the partition wall 4 of the expansion chamber, and the sound pressure decreases toward the left space. . That is, in this resonance mode, a resonance mode is generated in which the partition wall 4 resonates by moving the air in the left-right direction in the chamber, and the sound pressure near the connection portion of the second tube 2 is reduced. It becomes a resonance mode. In this mode, air vibrates so that air flows in a direction perpendicular to the central axis m2 of the second pipe 2 near the connection portion with the second pipe 2, so that air enters and exits the second pipe 2. It is hard to occur.

In the embodiment, the sound pressure generated in the first tube in the frequency band near the first resonance frequency f1 is determined according to the relationship between the resonance mode and the arrangement of the connection portions of the first tube and the second tube. As compared with the above, the sound pressure generated in the second tube is reduced, and the sound attenuation is increased.

Thus, according to the silencer of the above-described embodiment, by providing the partition wall 4 of a specific form in the expansion chamber, it is possible to generate a resonance mode that effectively increases the acoustic attenuation amount. The silencing characteristic can be enhanced near a specific frequency.

From the viewpoint of more effectively generating the resonance mode as described above by adding the partition wall, the height H of the partition wall 4 measured along the first direction X is set to be the first direction of the chamber. The length LX is preferably 1/5 to 2/3, and particularly preferably 1/4 to 1/2. If the height H is low, the resonance mode as shown in FIG. On the other hand, if the height H is too large, the ventilation resistance of the silencer 10 may increase.

The first resonance frequency f1 at which the resonance mode as shown in FIG. 4 occurs can be adjusted as follows. When the first direction length LX and the second direction length LY of the expansion chamber are increased, the first resonance frequency f1 changes in a lower direction. Further, when the height H of the partition wall 4 is increased, the first resonance frequency f1 changes in a slightly lower direction.

When the first direction length LX and the second direction length LY of the expansion chamber are set to about 70 to 150 mm, and the height H of the partition wall 4 is set to about 25 to 70 mm, the first resonance frequency f1 is set to 1000 Hz to 1500 Hz. In particular, as a silencer for an intake system of an automobile engine equipped with a turbocharger, it exhibits particularly preferable characteristics.

In the above embodiment, the acoustic attenuation is improved near the second resonance frequency f2. FIG. 6 shows the sound pressure distribution (resonance mode) in the expansion chamber around the second resonance frequency f2 (2355 Hz), and FIG. 7 shows the comparative example.
In the comparative example of FIG. 7, the sound pressure is high in the space on the left side and the space on the right side of the expansion chamber, and resonance modes having opposite phases at each position are observed. Although a certain sound attenuation effect is generated by this resonance mode, a higher sound pressure in the left space in the chamber is transmitted to the second tube side, and the sound attenuation amount is reduced.
On the other hand, in the embodiment of FIG. 6, high sound pressure is generated in the opposite phase in the lower left space and the lower right space separated by the partition wall 4, and there is a low sound pressure region in the space between them and the upper space. Appears. Even in this mode, the air vibrates so that the air flows in a direction orthogonal to the central axis m2 of the second pipe 2 in the vicinity of the connection portion with the second pipe 2, so that the air enters and exits the second pipe 2. Is less likely to occur.

Due to the relationship between the resonance mode and the arrangement of the connection portions of the first tube and the second tube, the sound pressure of the second tube 2 is reduced even in the vicinity of the second resonance frequency f2, and the sound is reduced. Attenuation increases. It should be noted that the improvement of the sound attenuation near the second resonance frequency f2 may not be as remarkable as in the above embodiment because the appearing frequency is a relatively high frequency.

The invention is not limited to the embodiment described above, and can be implemented with various modifications. Although other embodiments of the invention will be described below, in the following description, portions different from the above-described embodiment will be mainly described, and detailed descriptions of the same portions will be omitted. Moreover, these embodiments can be implemented by combining some of them or replacing some of them.

If the resonance mode as described above occurs, the form of the partition wall 4 may be changed.
For example, the partition wall 4 may be a plate-like one standing from the wall surface toward the inside of the expansion chamber, or may be a pleated one formed by recessing the wall surface of the expansion chamber. Good.

Moreover, in the said embodiment, although the partition wall 4 is provided in flat form so that the 3rd direction Z may be followed, the curved form may be sufficient. Moreover, in the said embodiment, although the height H of the partition wall 4 was constant over the 3rd direction Z, the height H of the partition wall may be changing over the 3rd direction Z. Further, the partition wall 4 does not have to completely partition the right side portion of the internal space of the chamber, and the partition wall 4 may be provided with a through hole or a slit. Two or more partition walls may be provided, but from the viewpoint of easy acoustic control in the chamber, it is preferable that the number of partition walls is one.

In the above description of the first embodiment, an example in which the silencer 10 is configured by a tube or an expansion chamber independent of other members has been shown. However, these tubes and the expansion chamber need not necessarily be independent. Alternatively, it may be integrated with other members. For example, a part of an air cleaner module provided in an intake system of an automobile engine or a part of a cooling air blower may be configured as the above-described silencer 10. That is, the muffler 10 may be a unit integrated with such an air cleaner module or a blower.

The silencer of the above embodiment can be used, for example, in an intake system of an automobile engine and has high industrial utility value.

10 Silencer 1 First tube 2 Second tube 3 Expansion chamber P1 First surface P2 Second surface X First direction Y Second direction Z Third direction LX First chamber length LY Expansion chamber Second direction length LZ Third chamber length 4 of expansion chamber Partition wall H Height of partition wall

Claims (2)

A muffler that muffles noise propagating through a pipe,
The silencer is a rectangular parallelepiped expansion chamber,
A first tube connected to a substantially central portion of the first surface of the chamber;
A second tube connected to a substantially central portion of the second surface of the chamber adjacent to the first surface;
The first tube side is connected to a noise source;
The normal direction of the first surface is the first direction,
The normal direction of the second surface is the second direction,
The direction orthogonal to the first direction and the second direction is the third direction,
A partition wall is erected so as to extend in the first direction from the surface facing the first surface of the chamber,
When viewed along the third direction, the internal space of the chamber is partitioned in a U shape by the partition wall,
And the silencer in which the partition wall is provided so that the position of the 2nd direction of a partition wall may substantially correspond to the position of the 2nd direction of the center of the connection part of a 1st pipe | tube. The silencer according to claim 1, wherein the height of the partition wall measured along the first direction is 1/5 to 2/3 of the length of the chamber in the first direction.