KR20180001926A - Duct system - Google Patents

Abstract

Disclosed is a duct system capable of blocking noise introduced into an inside space. The duct system according to an embodiment of the present invention comprises: a main duct transferring air; and a branch duct branched from the main duct and extended to the inside space to supply air transferred through the main duct to the inside space. The branch duct is provided to have a length of {(2n-1)}/4 wherein stands for a noise wave and n stands for natural number. According to an embodiment of the present invention, the duct system is able to effectively prevent noise from being introduced to the inside space by adaptively using a frequency (wave) of the noise, and is able to reduce the noise without reduction of flow pressure of the air.

Description

DUCT SYSTEM {DUCT SYSTEM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duct system, and more particularly, to a duct system capable of introducing air into an indoor space and blocking noise.

Generally, the ship is equipped with a duct system to supply air to the indoor space. The duct system is configured to blow air into the duct by the fan. A duct silencer is installed in the middle of the duct to block the noise transmitted through the duct. The duct silencer can be provided, for example, with a structure in which a porous material is inserted in the middle of the duct by machining it into a shape that allows air to pass through it. The noise changes into thermal energy in the porous material, thereby reducing the acoustic energy of the noise. Such a duct silencer is advantageous for reducing broadband noise, but since it is installed on the air flow path, the noise can be reduced and the air pressure flowing into the duct can be a friction factor, thereby reducing the flow pressure. In addition, the conventional duct silencer has an advantage of reducing broadband noise. However, since the duct noise silencer has noise that concentrates on a specific frequency band due to the rotation of the fan, for example, rumble noise or high frequency noise, Which is not suitable for effectively reducing the amount of water.

The present invention provides a duct system capable of effectively reducing noise at a frequency (wavelength) of noise and capable of reducing noise without decreasing the flow pressure of air.

The problems to be solved by the present invention are not limited to the above-mentioned problems. Other technical subjects not mentioned will be apparent to those skilled in the art from the description below.

According to an aspect of the present invention, there is provided a duct system including: a main duct for conveying air; (2n-1) lambda} / 4 length (where lambda is a noise wavelength and n is a natural number) branched from the main duct and extending to the indoor space so as to supply the air delivered through the main duct to the indoor space. And a branch duct provided so as to have a plurality of branch ducts.

The branch duct may introduce the air into the indoor space through the open end on the indoor space side and reflect the noise transmitted through the main duct so as not to enter the indoor space.

The branch duct includes: a fixed duct branching from the main duct; And a variable duct slidably coupled to the fixed duct so that the length of the branch duct can be varied according to the wavelength of the noise.

Wherein the duct system comprises: a measuring unit for measuring a wavelength or frequency of the noise or measuring a degree of vibration of the branch duct; And a driving unit for driving the variable duct according to at least one of the wavelength of the noise, the frequency of the noise, and the degree of vibration.

Wherein the duct system further comprises a control unit for calculating a target length of the branch duct based on at least one of the wavelength of the noise and the frequency of the noise, and the driving unit controls the variable duct according to a target length of the branch duct Can be driven.

According to the embodiments of the present invention, a duct system capable of reducing noise effectively in a frequency (wavelength) of noise and capable of reducing noise without decreasing the flow pressure of air is provided.

The effects of the present invention are not limited to the effects described above. Unless stated, the effects will be apparent to those skilled in the art from the description and the accompanying drawings.

1 is a cross-sectional view schematically illustrating a duct system 10 according to an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a branch duct 14 constituting a duct system according to an embodiment of the present invention.
3 is a graph showing the relationship between the number of waves and the acoustic impedance of a branch duct of a duct system according to an embodiment of the present invention.
4 is a perspective view showing a duct system 10 according to another embodiment of the present invention.
5 and 6 are cross-sectional views of a duct system 10 in accordance with further embodiments of the present invention.

Other advantages and features of the present invention and methods of achieving them will be apparent by referring to the embodiments described hereinafter in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and the present invention is only defined by the scope of the claims. Although not defined, all terms (including technical or scientific terms) used herein have the same meaning as commonly accepted by the generic art in the prior art to which this invention belongs. A general description of known configurations may be omitted so as not to obscure the gist of the present invention. In the drawings of the present invention, the same reference numerals are used as many as possible for the same or corresponding configurations. To facilitate understanding of the present invention, some configurations in the figures may be shown somewhat exaggerated or reduced.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises", "having", or "having" are intended to specify the presence of stated features, integers, steps, operations, components, Steps, operations, elements, parts, or combinations thereof, whether or not explicitly described or implied by the accompanying claims.

The duct system according to the embodiment of the present invention is formed such that the length of the branch duct that branches from the main duct to the indoor space for conveying air is {(2n-1)?} / 4 (where λ is a noise wavelength and n is a natural number) . According to the present embodiment, since the acoustic impedance to the noise frequency is infinite by the branch duct, the noise is reflected without being introduced into the indoor space, and only the air flows into the indoor space, so that the noise in the indoor space can be reduced .

In one embodiment, the branch duct may be provided with a variable length so as to adaptively reduce the noise at the frequency (wavelength) of the noise. For example, the branch duct may be provided with a variable duct slidably coupled to the fixed duct. Also, the duct system measures the wavelength or frequency of the noise, measures the degree of vibration of the branch duct, drives the variable duct according to the wavelength of the noise, the frequency of vibration or the degree of vibration of the branch duct, It can be configured to be automatically adjusted.

1 is a cross-sectional view schematically illustrating a duct system 10 according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a branch duct 14 constituting a duct system according to an embodiment of the present invention. Referring to FIGS. 1 and 2, the duct system 10 may include a blower 11, a main duct 12, and a branch duct 14. The main duct 12 is provided for transferring the air blown by the blower 11 (arrows F and F2 in Fig. 2). The blower 11 may be composed of one or a plurality of fans. The flow of the air blown by the blower 11 is shown by arrows in Figs. 1 and 2. Fig.

The branch duct 14 branches off from the main duct 12 and extends into the indoor space. The air introduced through the main duct 12 flows into the indoor space through the open end of the indoor space. The branch duct 14 is provided with an open end at an end on the indoor space side to introduce air (F1) into the indoor space. Although the branch duct 14 is formed in a direction perpendicular to the main duct 12 in the illustrated embodiment, the branch duct 14 may be inclined to the main duct 12.

Noise is generated in the duct system 10 due to the operation of a fan of the blower 11 and noise can be introduced into the indoor space together with the noise through the main duct 12 and the branch duct 14. [ In the present embodiment, the branch duct 14 is configured such that {(2n-1)?} / 4 (? Is the noise wavelength, n Is a natural number) length (l).

According to this embodiment, the length (1) of the branch duct 14 is designed to be {(2n-1) λ} / 4 (λ: noise wavelength, n: natural number) The noise transmitted through the main duct 12 is reflected without passing through the branch duct 14 and thus the noise introduced into the indoor space is blocked. The acoustic impedance means the ratio of the velocity of the medium particle to the sound pressure generated by the perturbation of the sound wave during propagation of the sound wave, as shown in Equation 1 below.

[Formula 1]

(Z: acoustical impedance, p: sound pressure, u: speed of medium particles)

Acoustic impedance can be expressed as a function of frequency and position. For an open tube, the acoustic impedance on the open side is 0 and the reflection coefficient is -1. Assuming that the sound waves are harmonics of a specific frequency composed of a sinusoidal wave or a cosine wave, the sound pressure in the open tube can be expressed by the following Equation 2, and the velocity of the medium particle can be expressed by Equation 3 below.

[Formula 2]

(P: sound pressure, P ⁺ : reference sound pressure value, k: wave number, d: position from the end of the branch duct)

[Formula 3]

(U: velocity of the medium particle, U ⁺ : reference velocity value, k: wavenumber, d: position from the end of the branch duct)

From the above equations 2 and 3, the following equations 4 and 5 are derived.

[Formula 4]

where p is the sound pressure, P ^{+ is the} reference sound pressure value, k is the wave number, d is the position from the end of the branch duct, w is the angular frequency, l is the length of the branch duct, x is the position from the branch point with the main duct, ₀ : Sound pressure at the junction with the main duct)

[Formula 5]

(u: velocity of medium particles, P _0: sound pressure at the branch point in the main duct, Z _0: impedance of air, k: wave number, w: length of the branch duct, x:: angular frequency, ℓ from the branch point with the main duct Position)

According to the acoustic impedance definition of Equation 1, Equation 4 and Equation 5, the acoustic impedance has a tangent function form as shown in Equation 6 below.

[Formula 6]

{Z (d): Acoustic impedance according to position, Z ₀ : Impedance of air, k: Wave number, d: Position}

3 is a graph showing the relationship between the number of waves and the acoustic impedance of a branch duct of a duct system according to an embodiment of the present invention. 3, when the length (l) of the branch duct is (2n-1) / 4 (n is a natural number) of the wavelength corresponding to the noise frequency, the acoustic impedance becomes infinite . When acoustic impedance is infinite, progressive sound waves are reflected without passing through that point. Accordingly, the air flow from the noise source is smoothly supplied to the indoor space through the open pipe of the branch duct 14, the noise frequency band is reflected by the impedance close to infinity without passing through the branch duct 14, It is not conveyed to the staying prisoner.

Therefore, when designing a duct system, it is necessary to predict or measure the characteristics of the noise caused by the fan, determine the frequency at which the noise is concentrated, and then determine the frequency at which the noise is concentrated at (2n-1) / 4 times By supplying the air through the branch duct, it is possible to reflect only the noise of the frequency and let air pass through. This duct system has the effect of blocking the noise without adding a separate device such as a duct silencer by adjusting only the length of the branch duct having the air transfer function.

4 is a perspective view showing a duct system 10 according to another embodiment of the present invention. In describing the embodiment of FIG. 4, redundant description may be omitted for the same or corresponding configuration as described above. Referring to FIG. 4, the branch duct 14 may include a fixed duct 142 and a variable duct 144. The fixed duct 142 branches from the main duct 12 and is fixedly installed.

The variable duct 144 can be slidably coupled to the fixed duct 142 so that the length (l) of the branch duct 14 can be varied according to the wavelength of the noise. In the illustrated embodiment, the variable duct 144 is slidably coupled to the fixed duct 142 while being inserted into the fixed duct 142, but may be provided to be slidably inserted into the fixed duct 142 . Both the fixed duct 142 and the variable duct 144 are provided at both ends as an open end so that air can be supplied to the indoor space. The variable duct 144 has a second guide portion 144a coupled to the first guide portion 142a provided in the fixed duct 142. [

4, since the variable duct 144 is slidably coupled to the fixed duct 142, the length (l) of the branch duct 14 is adaptively adjusted to the wavelength of the noise, Can be improved. For example, the user on the indoor space side can find the position of the variable duct 144 where the noise introduced through the branch duct 14 is minimized while adjusting the variable duct 144. Therefore, by adjusting the position of the variable duct 144 adaptively to the change in the frequency (wavelength) of the noise caused by the change in the number of the fans in the ventilation system, the change in the rotational speed of the fan, and the like, .

5 and 6 are cross-sectional views of a duct system 10 in accordance with further embodiments of the present invention. In describing the embodiments of Fig. 5 and Fig. 6, redundant explanations can be omitted for the same or corresponding configurations as described above. 5 and 6, the duct system 10 differs from the above-described embodiment in that the duct system 10 further includes a measuring unit 16, a control unit (not shown), and a driving unit 18.

The measurement unit 16 is installed in the main duct 12 or the branch duct 14 to measure the wavelength or frequency of the noise or measure the degree of vibration of the branch duct 14. [ The control unit (not shown) calculates the target length of the branch duct 14 based on the wavelength or the frequency of the noise measured by the measuring unit 16. When the target length is calculated by the control unit, the driving unit 18 drives the variable duct 144 in accordance with the calculated target length of the branch duct 14 so that the length (l) of the branch duct 14 becomes 2n-1) / 4 times. Or the driving unit 18 may drive the variable duct 144 according to the degree of vibration measured by the measuring unit 16 to adjust the length l of the branch duct 14. [

For example, as shown in Fig. 5, when the measuring unit 16 (for example, a vibration sensor) capable of measuring vibration is installed in the branch duct 14, the reference value is set to the branch duct 14 The vibration of the variable duct 144 due to the change of the position of the variable duct 144 while the variable duct 144 moves along the fixed duct 142 is detected by the measuring unit 16, And then the variable duct 144 having the minimum degree of vibration is located to finally locate the position of the variable duct 144 to drive the variable duct 144 to block the noise.

As another example, when a measuring section 16 (for example, a sound wave analyzer) capable of analyzing the frequency of noise is installed inside or outside the main duct 12 as shown in Fig. 6, the largest acoustic energy And calculates the target length of the branch duct 14 on the basis of the noise frequency (or wavelength) and calculates the target length of the branch duct 14 based on the calculated noise frequency (or wavelength) The variable duct 144 can be driven to block noise from flowing into the indoor space.

Various mechanism mechanisms can be applied to the drive unit 18. For example, the driving unit 18 may drive the variable duct 144 with a hydraulic cylinder, a rack / pinion structure, a screw shaft structure, or other driving method. Further, the variable duct 144 is not limited to be driven by the slide coupling structure. The variable duct 144 may be coupled to the fixed duct 142 so as to be coupled / disassembled by a bolt / nut, Various methods other than the illustrated embodiments may be applied.

According to the embodiment of the present invention, noise can be shut off without providing a duct silencer made of a porous material or the like in the main duct or the branch duct. Therefore, it is possible to reduce noise without decreasing the flow pressure of air, it is possible to effectively prevent the noise of a specific frequency from being introduced into the indoor space.

It is to be understood that the above-described embodiments are provided to facilitate understanding of the present invention, and do not limit the scope of the present invention, and it is to be understood that various modifications are possible within the scope of the present invention. It is to be understood that the technical scope of the present invention should be determined by the technical idea of the claims and the technical scope of protection of the present invention is not limited to the literary description of the claims, To the invention of the invention.

10: duct system 11: blower
12: main duct 14: branch duct
142: fixed duct 142a: first guide part
144: variable duct 144a: second guide portion
16: measuring part 18:

Claims (5)

A main duct for conveying air; And
(2n-1) lambda} / 4 length (where lambda is a noise wavelength and n is a natural number) branched from the main duct so as to supply the air delivered through the main duct to the indoor space. A duct system comprising a branch duct provided. The method according to claim 1,
The branch duct comprises:
Wherein the air introduced into the indoor space through the open end of the indoor space side is reflected to prevent the noise transmitted through the main duct from flowing into the indoor space. The method according to claim 1,
The branch duct comprises:
A fixed duct branching from the main duct; And
And a variable duct slidably coupled to the fixed duct so that a length of the branch duct can be varied according to a wavelength of the noise. The method of claim 3,
A measuring unit measuring the wavelength or frequency of the noise or measuring the degree of vibration of the branch duct; And
And a driving unit for driving the variable duct according to at least one of the wavelength of the noise, the frequency of the noise, and the degree of vibration. 5. The method of claim 4,
Further comprising a control unit for calculating a target length of the branch duct based on at least one of the wavelength of the noise and the frequency of the noise,
Wherein the driving unit drives the variable duct according to a target length of the branch duct.

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