JPH02102313A - Muffling device for chamber - Google Patents

Abstract

PURPOSE:To obtain a muffling device of chamber capable of damping noise even at low frequency zone effectively in the extreme by incorporating or providing on the chamber one or multiple resonance cylinders of which one end is open and the other is closed and having a depth of about a quarter of a target noise wave length. CONSTITUTION:A muffling device 1 of a chamber is so constructed that four resonance cylinders 4a to 4d are incorporated in, for example, a chamber 3 made of galvanized sheet with a gas delivery opening 2, 2 in two directions. A duct 5 is connected to one of the gas delivery opening 2, 2; a fan 6 is connected to the other opening 2 through a canvas connector 7. The resonance cylinders 4a to 4d are so formed that, for example, galvanized sheet 8 is folded several times in Z form, each one of the bottoms in opened in wedge form and the other is closed and the depth of each of the resonance cylinders 4a to 4d is a quarter of the noise wave length to which noise is desired to be lowered. Also the open ends 11 of the resonance cylinders 4a to 4d are faced toward the air passage 12 of the chamber 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a silencing device for a building air conditioner or various smoke evacuation devices, and particularly to a silencing device for a chamber.

[Prior Art] Conventionally, sound damping devices have been known in which, for example, a chamber is covered with a porous sound-absorbing material, or a large-volume chamber is provided at the outlet of a blower to function as a cavity-type muffler. There is.

[Problems to be Solved by the Invention] However, although porous sound-absorbing materials can reduce high-frequency noise, they have a poor sound-absorbing effect on low-frequency noise and cannot eliminate it.

On the other hand, for cavity-type silencers, in order to improve the attenuation value, the cross-sectional enlargement ratio must be increased (for example, several tens of times).
In some cases, it may not be possible to obtain the required dimensions due to bulk or space constraints.

The present invention was made in view of the problems of such conventional devices, and does not require an extremely large installation space.
Another object of the present invention is to provide a chamber muffling device that can extremely effectively attenuate low frequency noise.

[Means for Solving the Problems] The present invention has been completed in accordance with the above-mentioned objects, that is, the present invention has the following features: (1) One end is open at one end and the other end is closed at a depth of approximately one quarter of the target noise wavelength. A silencing device for a chamber (Claim 1), characterized in that a plurality of resonance cylinders are built in or externally mounted in a chamber, and the open ends of the resonance cylinders are made to face the air passage (claim 1); (2) the resonance cylinder is A silencer for a chamber according to claim 1 (claim 1), wherein a hollow part with a small diameter through hole is formed in the cylindrical wall and a resonance chamber that resonates at or near the target noise frequency is provided. Section 2),
(3) One or more resonant cylinders with one end open and the other end closed and having a depth of approximately one-fourth of the target noise wavelength, the open end facing the air passage of the chamber, and the body thereof being curved. A silencer for a chamber (Claim 3), characterized in that the chamber has a hollow portion formed with a small-diameter through-hole built into or externally installed in the chamber; The gist of the present invention is a silencing device for a chamber (Claim 4) characterized in that a resonant chamber is formed by having holes facing the air passage of the chamber to resonate at or near a target noise frequency. .

[Function] As a result, the chamber silencing device of the present invention resonates with the target noise frequency component of the noise propagated in the tact, such as the air in the resonance tube or resonance chamber provided in the chamber, or the sound of a blower, and vibrates violently. Attenuates noise by converting it into energetic heat.

[Example] Hereinafter, an example will be described with reference to the drawings (first of all, see FIGS. 1 and 2). In these figures, 1 is a silencer for a chamber according to the present invention; In the example, a chamber 3 made of, for example, a galvanized iron plate and having air supply openings 2, 2 in two directions has four resonant cylinders 4a to 4d built therein. Note that 5 in the figure is a duct connected to one of the air supply openings 2, 2, and 6 in the figure is a fan connected to the other opening 2 via a canvas joint 7.

The wooden resonance cylinders 4a to 4d are formed by, for example, folding a galvanized iron plate 8 several times in a two-shape shape to form four wedge-shaped resonance cylinders with one end open and the other end closed in each valley, and the chamber 3
Upper and lower inner surfaces 9. It spans a total height of 10 meters and is fixedly built in with its plate surface standing upright.

Here, depths 1 to 4 of each resonant tube are formed to be one-fourth of the wavelength of the target noise that is aimed at reduction.1For example, if the target noise frequency is 75H7, the depth of the tube is about 111cm; For 130H2, set it to 64cm, and for 230Hz, set it to about 36cm.

Note that the target noise wavelength is generally one with a large noise component, such as the rotating sound of a fan, but it is also set to a target wavelength depending on individual problems such as resonance of surrounding components (not shown) of the tact. .

The open ends 11 of the resonance cylinders 4a to 4d...
In this example, the air passage 1 of the chamber is aligned with the opening direction.
2 is being interviewed. As a result, the air within the resonant cylinder having a quarter wavelength depth resonates with the noise of the target frequency and vibrates violently with a moat having a peak at the open end 11.

Next, the embodiments shown in FIGS. 3 and 4 will be explained. Like the above embodiments, these have a built-in resonant tube in the chamber, but the difference is that the embodiment shown in FIG. The shapes of the cylinders 4a to 4c are replaced with the above-mentioned horizontal shape and have a rectangular cross section.Of course, each cylinder has a depth of about 1/4 of the target noise wavelength, and as a result of arranging 4 magnolias in the order of wavelength, the open ends 11 of these resonant cylinders are ...are arranged in a staircase pattern.

On the other hand, the resonator cylinders 4a to 4c of the embodiment shown in FIG. ...are aligned diagonally in a line. It should be noted that both of the resonance cylinders of the first and second embodiments share the cylinder wall in whole or in part with an adjacent resonance cylinder.

Next, in the embodiment shown in FIG. 5, similar to the embodiment shown in FIG. However, on the other hand, a small-diameter through hole 13 is opened near the tip of the reverse wedge-shaped cylinder wall that corresponds to the peak (i.e., near the opening end 11 of the resonance cylinder), and this is The hollow part 15 formed in the wedge-shaped cylinder wall 14 is connected to resonate at the target noise frequency (in this example, it corresponds to the target value of each communicating resonant cylinder) or a value close to it. It is particularly different in that resonance chambers 16a to 16d are provided. Note that 17 in the figure is a partition wall of the resonance chamber, which is arranged and fixed at a predetermined position after calculating the volume of the resonance chamber, and the resonance chambers 16a to 16d and the remaining hollow part 18 in the cylinder wall are connected to each other. Closely partitioned.

Here, the dimensional relationship of the resonance chamber is determined by the target noise frequency to be reduced, that is, the volume of the hollow part V,
The cross-sectional area of the hole is 5, the effective length of the neck of the hole is taken, the mass of air per unit volume is ρ, the bulk modulus of elasticity is K, and the resistance per unit area of the neck of the hole is r and mo. As the interlocking velocity V of the air at the neck of the through hole, the outdoor sound pressure (P
The inertial force of the air inside the perforation (sJL
ρx dv/dt), the frictional resistance (srv) of the neck and the compression reaction force of the hollow air ((s2/v)Jvdt)
Considering the balance, PXe multiplied by jω = sJ1ρX
Since it can be expressed as dv/dt+S rV + (s 2 K/V) fvdt,
Solving this, impedance 2 is Z = s p / v = s r + j (ω5lp-s2 g/ (ωV))
Then, if we rearrange ω with the imaginary part in curly brackets as 0 and find the resonance frequency f (here = ρc2; c is the speed of sound, approximately 334 m/5ec), then f = ω/(2π) = (c/ (2π) )) X 5QR(s/ (MV
)) get. In addition, if we let the sentence → 0 here, then f = (c
/ (2π) ) X 5QR (d/V) (d is the diameter of the through hole).

Therefore, the dimensional relationship of each resonance chamber in this example is, for example, when the target frequency is 75H2, the diameter of the through hole 13 (7) is 1
If taken in cm, the volume of the hollow part 15 is 5027 cm3 (
If it were made into a cube, each side would be 17.1 cm). Of course, these dimensional relationships can be changed in various ways while satisfying the above formula. For example, if the diameter of the small diameter through hole is 5 cm, the hollow volume will be 25,000.
It is just over cm3.

Similarly, for example 130)1. If the diameter of the through hole is 1 cm in a resonant chamber with the target frequency as
3. For example, in a resonance chamber with a target value of 230H, the hollow volume when the through hole diameter is 1 cm is 535 cm.
It is 3.

Next, the embodiment shown in FIG. 6 is a resonance cylinder 4a.

4b is externally packaged in the chamber 3, and in this example, it is arranged parallel to the installation direction of the tact, so that it can be housed compactly. In addition, of course, each resonance tube 4a, 4b
is a cylindrical body with one end open and the other end closed, which has a depth of approximately one-fourth of the target noise wavelength, and is installed in a through hole 19 formed in the side plate of the chamber in this example, thereby creating an air passage 12 in the chamber. The opening end 11 of the resonator cylinder is made to face the opening end 11 of the resonator cylinder.

Further, 20 in the figure is a bottom plate at the closed end of the resonance cylinder.

On the other hand, the embodiments shown in FIGS. 7 to 9 are particularly different from the above-described embodiments in that each of the chambers has a curved resonant cylinder built-in or externally mounted thereon. First, the embodiment shown in FIG. A resonant cylinder 4a with one end open and the other end closed, with a cylinder depth (11 to 3) approximately one-fourth of the target noise wavelength.
4c to 4c are made of 3 wood, the open end 11-... is made to face the air passage 12 of the chamber, and the body part 21...
This is an example in which a relatively long resonant cylinder can be housed compactly.

The embodiment shown in FIG. 8 is intended to reduce the processing cost of such a curved resonant cylinder, and the resonator cylinder 4 of this example is made of a flexible cylinder 22 (for example, made of aluminum, iron, stainless steel, etc.). (Flexible metal tubes are known, and if it is made of other materials, it is preferable to use one that has undergone nonflammable treatment.) It is used with one end closed, and can be easily bent by hand on site. It is attached to a through hole 19 formed in the top plate of the chamber, and is bent in any direction depending on the site situation to be packaged. In addition, this example resonance tube 4
Of course, along the curved shape, approximately one-fourth of the target noise wavelength
It has a depth, and its opening end 11 is connected to the through hole 1.
9 and faces the air passage 12 of the chamber.

Furthermore, in the embodiment shown in FIG. 9, a relatively long resonance cylinder 4 is provided with a through hole 1 having an open end 11 in the top plate of the chamber.
9 and face the air passage 12 of the chamber, while its body is spirally curved and wrapped around the outer circumference of the tact, which is cylindrical in this example (a rectangular cylindrical shape is also possible). This is an example of the arrangement. Note that, of course, the depth of the tube along the spiral shape is approximately one-fourth of the target noise wavelength, and even in the case of long wavelengths, it is an example that can be installed relatively compactly.

In addition, it is also possible to add a resonance chamber to the cylinder wall 14 of such a curved or external resonance cylinder, including those shown in FIGS. 6 to 8, in accordance with the embodiment shown in FIG. 5. .

Next, in the embodiment shown in FIG. 1O, resonance chambers 16a to 16d having small-diameter through holes 13 are formed in the chamber 3, and noise is attenuated by resonance of the air in the resonance chambers. In this case, three hollow parts with small diameter through holes 13 are built in (15a to 15C in the figure) L/, and one additional hollow part (15d in the figure) is installed, and each small diameter through hole 13... is installed in the chamber. It faces the air passage 12.

Here, the relationship between the volume of the resonance chamber and the target noise frequency can be designed in the same manner as described in the embodiment shown in FIG.

Note that common items in each embodiment are designated by the same numbers in the drawings, and a portion of the explanation will be omitted.

In addition, the shape of the resonance cylinder can of course be made into various shapes such as a cylindrical shape or a prismatic shape. Further, one or more resonant tubes may be provided depending on the target noise wavelength. For example, it is also possible to form a large number of resonant tubes by partitioning the inside of the chamber into a grid pattern.

Furthermore, such a silencer may also be equipped with a sound absorbing material such as glass wool or rock wool, and examples of where to install it include, for example, in the chamber shown in FIG. It is possible to line the inner circumferential surface of the resonant tube, or insert it into the bottom of the resonant tube (the depth of the tube is determined taking this into consideration), or the tube wall itself can be made of these sound-absorbing materials. It is possible. Furthermore, as in the embodiments shown in FIGS. 1 and 2, when a hollow part is formed between the cylinder walls of each resonant cylinder, the cylinder wall is formed of punched metal, and the hollow part is made of the above-mentioned class. It can be filled with sound absorbing material such as wool.

In addition, when a resonance chamber is installed together with a resonance tube, the target noise frequency thereof may be slightly shifted from the target value of the communicating resonance tube to make the resonance bimodal.

In addition, the chamber equipped with these resonance tubes or resonance chambers is
It is preferable to cover it with a heat insulating material such as glass wool (not shown) to keep the temperature-controlled air warm and prevent condensation.

Although the embodiment is configured as described above, the present invention includes a resonance tube, a chamber, an air passage, an open end of the resonance tube, a small-diameter through hole, a hollow portion, a tube wall, a resonance chamber, a resonance tube, as long as it does not contradict the gist of the invention. It goes without saying that the specific structure, shape, dimensions, material, number, arrangement, and relationships thereof of the body, etc. of the body can be variously modified and are not limited to the above-mentioned embodiments.

[Effects of the Invention] The chamber silencing device of the present invention has the following effects when configured as described above.

That is, the chamber has a built-in or external resonant cylinder having a depth of approximately one-fourth of the target noise wavelength, or a resonant chamber that resonates at the target noise frequency or a value in its vicinity is formed. According to the method, it has an effective silencing range that extends to the low frequency range, and it is possible to set one or more target noise frequencies and attenuate them intensively, and it is possible to obtain a high silencing effect with a simple means. It is possible to provide a chamber silencing device that is extremely practical.

If the resonant cylinder is built into the chamber or curved and externally packaged, it will not be bulky, and even if the mold cylinder is externally packaged, it can be placed along the takt direction, which saves space. There are very few restrictions on the arrangement of the chamber, etc., so there is no strain on the piping, etc.

Furthermore, in the silencer according to claim 2, the resonance cylinder has a resonance chamber that resonates at or near the target noise frequency by forming a hollow part with a small-diameter through hole in the cylinder wall. Therefore, by using baking soda in combination with the resonance cylinder and the resonance chamber formed on the cylinder wall, it is possible to dramatically improve the silencing effect.

[Brief explanation of the drawing]

The drawings show embodiments, and FIG. 1 is a perspective view of a silencing device of the present invention in which a resonance cylinder is built into a chamber, FIG. 2 is a cross-sectional view of the same device, and FIGS. Other embodiments of the silencing device are shown, and FIGS. 3 and 4 are cross-sectional views of the silencing device in which the shape of the resonant cylinder built into the chamber is changed, and FIG. Fig. 6 is a cross-sectional view of the muffler in which a resonance chamber is attached to the cylinder wall of the muffler;
The figure is a cross-sectional view of the silencer with a built-in curved resonance cylinder in the chamber, FIGS. 8 and 9 are perspective views of the silencer with the chamber equipped with a curved resonance cylinder, and FIG. 10 is a chamber. FIG. 2 is a cross-sectional view of the muffler in which a resonance chamber is formed. l...Chamber silencer 3...Chambers 4.4a to 4d...Resonance cylinder 11...Open end 12 of resonance cylinder...Air passage 3...Small diameter through hole 4...Cylinder Walls 5.15a to 5cm...Hollow parts 6a to 16d...Resonance chamber l...Body of resonance tube

Claims (4)

[Claims] (1) One or more resonant tubes with one end open and the other end closed, each having a depth of approximately one-fourth of the target noise wavelength, are built into or exteriorized in the chamber, and the open ends of the resonant tubes are made to face the air passage. A chamber silencer characterized by: (2) The resonator cylinder is provided with a resonance chamber that resonates at or near the target noise frequency by forming a hollow part with a small-diameter through hole in the cylinder wall. Chamber silencer. (3) One or more resonant cylinders having a depth of approximately one-fourth of the target noise wavelength and having one end open and the other end closed, the open end facing the air passage of the chamber, and the body thereof being curved. A silencing device for a chamber, characterized in that it is built-in or externally mounted in the chamber. (4) A hollow part formed by a small-diameter through-hole is built into or exteriorized in the chamber, and the small-diameter through-hole is made to face the air passage of the chamber to form a resonance chamber that resonates at the target noise frequency or a value in the vicinity thereof. A chamber silencer characterized by the following: