WO2021169678A1 - Noise-reducing air duct assembly used for duct-type air conditioner and design method for noise-reducing air duct assembly - Google Patents

Abstract

A noise-reducing air duct assembly (1) used for a duct-type air conditioner and a design method for the noise-reducing air duct assembly. The noise-reducing air duct assembly (1) comprises at least one stage of noise-reducing air duct sub assemblies (11, 12, 13). The noise-reducing air duct sub assemblies (11, 12, 13) comprise: separating tubes (110, 120, 130), which are connected to an air outlet of the duct-type air conditioner or air outlets of the previous stage of the noise-reducing air duct sub assemblies (12, 13), 2N sub separating tubes (1100, 1200, 1300) being respectively formed in the separating tubes (110, 120, 130); and an air duct group, comprising N sub air duct groups (1210, 1211, 1310, 1311), the sub air duct groups (1210, 1211, 1310, 1311) being connected to air outlets of the sub separating tubes (1100, 1200, 1300). The sub air duct groups (1210, 1211, 1310, 1311) comprise short tubes (12100, 12110, 13100, 13110) and long tubes (12101, 12111, 13101, 13111) which are provided in parallel, and length differences between the short tubes (12100, 12110, 13100, 13110) and the long tubes (12101, 12111, 13101, 13111) are set to be odd times the half-wavelength of sound waves.

Description

Noise reduction air duct assembly for air duct machine and design method thereof Technical field

The invention relates to the technical field of noise reduction of air duct machines, in particular to a noise reduction air duct assembly for air duct machines and a design method thereof.

Background technique

Ducting machine is the abbreviation of ducted air conditioner, which is a new type of air conditioner in recent years. Compared with the traditional on-hook or cabinet machine, the installed air duct machine is more concealed and more economical to use. At the same time, the pipe length is longer than ordinary household air conditioners, and the installation is more flexible. The external influence on aesthetics is increasingly used in household central air-conditioning systems.

Although the air duct machine has many advantages, it will generate a lot of noise during its use, which will reduce the user experience. The noise of the air duct machine mainly comes from the noise of the fan, and the frequency is relatively low. The current direction of noise reduction technology is mainly to optimize fan blades, volutes, and fan speed, that is, to reduce noise from the source of noise. This noise reduction method is costly, technically difficult, and has limited noise reduction effects. Can not meet customer needs.

Correspondingly, there is a need in the art for a new noise reduction air duct assembly for air duct machines and a design method thereof to solve the above-mentioned problems.

Summary of the invention

In order to solve the above-mentioned problems in the prior art, that is, in order to solve the problem of large noise of the existing air duct machine, the first aspect of the present invention provides a noise reduction air duct assembly for the air duct machine. The duct assembly includes at least one level of noise reduction air duct subassembly, and the noise reduction air duct subassembly includes: a dividing pipe connected to the air outlet of the air duct machine or the air outlet of the previous level of noise reduction air duct subassembly. 2N sub-dividing pipes are formed in the dividing pipe; a wind pipe group, which includes N sub-wind pipe groups, the sub-wind pipe group is connected to the air outlet of the sub-dividing pipe, the sub-wind pipe group includes parallel short pipes And a long tube, the length difference between the short tube and the long tube is set to an odd multiple of the half wavelength of the sound wave, where N is a positive integer.

In the above-mentioned preferred technical solution of the noise reduction air duct assembly for the air duct machine, the length difference between the short tube and the long tube is set to be equal to the half-wavelength of the sound wave.

In the above-mentioned preferred technical solution of the noise reduction air duct assembly for the air duct machine, the bending angle of the center line of the short pipe and/or the long pipe is greater than or equal to 120°.

In the above-mentioned preferred technical solution of the noise reduction air duct assembly for the air duct machine, the design method of the noise reduction air duct assembly includes:

Acquiring at least one effective muffling frequency at the air outlet of the air duct machine;

Determining the number of stages of noise reduction air duct sub-components included in the noise reduction air duct component based on the effective noise cancellation frequency;

Calculate the cross-sectional size of the dividing tube in the noise reduction air duct subassembly and the number of sub-dividing tubes contained in the dividing tube based on the cross-sectional size of the air outlet of the air duct machine and the number of stages of the noise reduction air duct subassembly ；

The length difference between the long pipe and the short pipe in the noise reduction air duct subassembly is calculated based on the effective noise reduction frequency corresponding to the noise reduction air duct subassembly.

In the above-mentioned preferred technical solution for the noise reduction air duct assembly of the air duct machine, the step of "obtaining at least one effective noise reduction frequency at the air outlet of the air duct machine" specifically includes:

Detecting noise information at the air outlet of the air duct machine within a range of 0.1 m-1 m from the geometric center point of the air outlet of the air duct machine;

Acquiring a 1/3 octave frequency spectrum of the noise information;

Determining the maximum sound pressure level based on the 1/3 octave frequency spectrum;

Determine a minimum sound pressure level based on the maximum sound pressure level and a preset sound pressure level threshold, and define each sound pressure level greater than or equal to the minimum sound pressure level as an effective sound pressure level;

Acquiring each frequency corresponding to the effective sound pressure level;

The respective frequencies are screened based on the cross-sectional size of the air outlet of the air duct machine to obtain at least one effective silencing frequency at the air outlet of the air duct machine.

In the above-mentioned preferred technical solution for the noise reduction air duct assembly of the air duct machine, the preset sound pressure level threshold is in the range of 4dB-10dB, and the minimum sound pressure level is equal to the maximum sound pressure level and the maximum sound pressure level. The difference of the preset sound pressure level threshold.

In the above-mentioned preferred technical solution for the noise reduction air duct assembly of the air duct machine, the step of "obtaining at least one effective noise reduction frequency at the air outlet of the air duct machine" further includes:

Before the step of obtaining the frequencies corresponding to the effective sound pressure levels, the effective sound pressure levels are sorted in descending order.

In the above-mentioned preferred technical solution for the noise reduction air duct assembly of the air duct machine, the step of "determining the number of stages of the noise reduction air duct sub-components contained in the noise reduction air duct assembly based on the effective noise reduction frequency" specifically includes :

The number of stages of the noise reduction air duct sub-components included in the noise reduction air duct component is set to be the same as the number of the effective noise reduction frequencies.

In the above-mentioned preferred technical solution for the noise reduction air duct assembly of the air duct machine, "calculate the noise reduction air duct based on the cross-sectional size of the air outlet of the air duct machine and the number of stages of the noise reduction air duct sub-assembly The steps of the section size of the dividing tube in the assembly and the number of sub-dividing tubes included in the dividing tube specifically include:

Setting the cross-sectional size of the dividing pipe to be the same as the cross-sectional size of the air outlet of the air duct machine;

Calculate the number of sub-dividing tubes included in the dividing tube according to formula (1):

M=2 ^N (1);

Among them, M is the number of sub-dividing pipes included in the dividing pipe, N is the number of stages corresponding to the noise reduction air duct sub-assembly, and N is a positive integer.

In the above-mentioned preferred technical solution for the noise reduction air duct assembly of the air duct machine, "calculate the long pipe and the short pipe in the noise reduction air duct subassembly based on the effective noise reduction frequency corresponding to the noise reduction air duct subassembly. The steps of "length difference between tubes" specifically include:

Calculate the length difference between the long pipe and the short pipe according to formula (2):

ΔL=(c/2f)*n (2);

Among them, ΔL is the length difference between the long tube and the short tube; f is the effective muffling frequency; c is the speed of sound; n is a positive odd number.

The noise reduction air duct assembly for air duct machines provided by the present invention uses a dividing tube and a plurality of air ducts to construct a multi-stage noise reduction air duct sub-assembly. The length difference is set equal to an odd multiple of the half-wavelength of the input noise sound wave, so that the noise reduction air duct sub-components of different levels can be used to reduce the noise of different frequencies, and realize the noise in the wider frequency range generated by the air duct machine. Targeted noise reduction processing greatly reduces the noise at the air outlet of the air duct machine. The noise reduction principle is achieved by using the interference silencing principle of sound waves, so that the noise reduction air duct assembly of the present invention has a simple structure, convenient installation, and no need for correction. The internal structure of the air duct machine is modified, and the noise reduction air duct component can be directly connected to the air outlet of the air duct machine during use. It is also applicable to the performance upgrade and transformation of the existing air duct machine, and the applicability is more powerful. In addition, the noise reduction air duct components can be customized for different noise frequencies to meet the individual needs of users, thereby greatly improving the user experience.

Furthermore, in the design of the noise reduction air duct sub-components at all levels, the length difference between the short tube and the long tube is set equal to the half-wavelength of the sound wave, which minimizes the noise reduction at all levels on the basis of ensuring the noise reduction performance. The overall length of the air duct subassembly is beneficial to increase the number of stages of the noise reduction air duct subassembly in a limited pipe arrangement space, thereby enhancing the noise reduction performance of the noise reduction air duct assembly.

Furthermore, by keeping the bending angle of the center line of the short tube and the long tube at 120° or more, it is ensured that the sound waves will not be reflected or interfered when the noise propagates in the long tube or the short tube. Ensure the smooth realization of the noise reduction function.

Another aspect of the present invention also provides a design method for noise reduction air duct components. It can be understood that based on this design method, the noise reduction air duct components described in any of the foregoing technical solutions can be designed, so the design method has All the technical effects of the aforementioned noise reduction air duct assembly will not be repeated here.

Description of the drawings

The noise reduction air duct assembly and its design method for the air duct machine of the present invention will be described below with reference to the accompanying drawings. In the accompanying drawings:

Figure 1 is a schematic diagram of the structure of the noise reduction air duct assembly of the present invention;

Figure 2 is a schematic diagram of the 1/3 octave frequency spectrum of the noise at the air outlet of the air duct machine;

List of reference signs:

1. Noise reduction air duct assembly; 10. Tail pipe; 11. Primary noise reduction air duct sub-assembly; 110, Primary separation pipe; 1100, Primary sub-separation pipe; 1101, Short baffle; 1102, Long baffle; 111, Primary Air duct group; 1110, primary short pipe; 1111, primary long pipe; 12, secondary noise reduction air duct sub-assembly; 120, secondary divider pipe; 1200, secondary sub-divided pipe; 121, secondary air duct group; 1210 , The first two sub-air duct group; 12100, the first two short pipe; 12101, the first two long pipe; 1211, the second second sub-air pipe group; 12110, the second second short pipe; 12111, The second second long pipe; 13, the third-level noise reduction air duct sub-assembly; 130, the third-level dividing pipe; 1300, the third-level sub-dividing pipe; 131, the third-level air duct group; 1310, the first and third-level sub-air duct group 13100, the first three-stage short pipe; 13101, the first three-stage long pipe; 1311, the second and third-stage sub-air duct group; 13110, the second three-stage short pipe; 13111, the second and third-stage long pipe.

Detailed ways

The preferred embodiments of the present invention will be described below with reference to the drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention, and are not intended to limit the protection scope of the present invention.

In addition, in order to better illustrate the present invention, numerous specific details are given in the following specific embodiments. Those skilled in the art should understand that the present invention can also be implemented without certain specific details.

It should be noted that in the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The term of the indicated direction or positional relationship is based on the direction or positional relationship shown in the drawings, which is only for ease of description, and does not indicate or imply that the device or element must have a specific orientation, be configured and operated in a specific orientation Therefore, it cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", and "fourth" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance.

In addition, it should be noted that, in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, they can be fixed or fixed. It is a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication between two components. For those skilled in the art, the specific meaning of the above-mentioned terms in the present invention can be understood according to specific circumstances.

Based on the large noise problem of existing air duct machines pointed out in the background art, the present invention provides a noise reduction air duct assembly for air duct machines and a design method thereof. The interference muffler principle is used to realize the realization with a simple structure. The purpose of noise reduction of the air duct machine.

The present invention is mainly based on two points: After the structure of the fan blades and the air duct is determined, the noise frequency characteristics remain basically unchanged at different fan speeds; the noise propagation path is constructed with a specific length difference, when the sound waves emitted by the noise source pass through two After the propagation paths of different lengths, the sound waves at the exit will have a phase difference. When the length difference of the propagation path of the sound waves is equal to an odd multiple of the half wavelength of the sound wave, the phases of the sound waves at the exit are completely opposite and cancel each other out. The noise reduction effect is produced, which is the principle of interference noise reduction in the present invention.

The noise reduction air duct assembly for air duct machines provided by the present invention includes at least one level of noise reduction air duct subassembly, and each level of noise reduction air duct subassembly mainly includes a partition tube and an air duct group composed of several air ducts. The dividing pipe is connected to the air outlet of the air duct machine or the air outlet of the previous stage noise reduction air duct subassembly, and 2N sub-dividing pipes are formed in the dividing pipe. The air duct group includes N sub-air duct groups, which are connected to the air outlet of the sub-dividing pipe. The sub-air duct group includes parallel short pipes and long pipes. The length difference between the short pipe and the long pipe is set to the half-wavelength of the sound wave. An odd multiple of, where N is a positive integer.

Figure 1 is a schematic diagram of the structure of the noise reduction air duct assembly of the present invention; Figure 2 is a schematic diagram of the 1/3 octave frequency spectrum of the noise at the air outlet of the air duct machine.

Referring to Figure 1, the noise reduction air duct assembly 1 in this embodiment includes three-stage noise reduction air duct sub-assemblies, which are respectively a primary noise reduction air duct sub-assembly 11, a secondary noise reduction air duct sub-assembly 12, and a three-stage noise reduction air duct subassembly. The duct sub-assembly 13, the noise reduction air duct sub-assemblies at all levels are connected in sequence to construct an air duct that can eliminate noise of three frequencies. The air outlet of the primary noise reduction air duct subassembly 11 is connected to the tail pipe 10, which serves as a noise outlet; the air inlet of the three-stage noise reduction air duct subassembly 13 is connected to the air outlet of the air duct machine as a noise inlet. Each level of noise reduction air duct sub-assembly includes a partition pipe and a duct group composed of several air ducts.

Specifically, the primary noise reduction air duct subassembly 11 includes a primary dividing pipe 110 and a primary air duct group 111. Continuing to refer to FIG. 1, a long partition 1102 is provided in the primary dividing tube 110, and the inner cavity of the primary dividing tube 110 is divided into two primary sub-dividing tubes 1100 with the same shape by means of the long dividing tube 1102. The primary dividing pipe 110 is connected to the air outlet of the previous level noise reduction air duct subassembly, that is, connected to the air outlet of the second level noise reduction subassembly. The primary air duct group 111 includes a sub-air duct group, which includes a primary short pipe 1110 and a primary long pipe 1111 in parallel, and the primary short pipe 1110 and the primary long pipe 1111 are connected in parallel to the air outlet of the primary sub-dividing pipe 1100. That is, the primary short tube 1110 is correspondingly connected to a primary sub-dividing tube 1100, and the primary long tube 1111 is correspondingly connected to a primary sub-dividing tube 1100. The length difference between the primary short tube 1110 and the primary long tube 1111 is set to an odd multiple of the half wavelength of the acoustic wave, which is related to the frequency of the noise output from the secondary noise reduction air duct subassembly 12. Preferably, the length difference between the primary short tube 1110 and the primary long tube 1111 is set to be equal to the half-wavelength of the acoustic wave, so as to ensure that the length of the primary short tube 1110 and the primary long tube 1111 is the shortest. The primary dividing pipe 110 is connected with the secondary air pipe group 121 in the secondary noise reduction air duct sub-assembly 12 in the form of plug or flange connection, and the air outlet of the primary air pipe group 111 is connected with the tail pipe 10 by plug connection or flange connection. And other ways to connect. Furthermore, a short partition 1101 is also provided in the primary dividing pipe 110, and the short partition 1101 is used to strengthen the connection with the secondary air pipe group 121 in the secondary air pipe group 121.

The design principle of the secondary noise reduction air duct subassembly 12 is the same as the design principle of the primary noise reduction air duct subassembly 11. Continuing to refer to FIG. 1, the secondary noise reduction air duct subassembly 12 includes a secondary dividing pipe 120 and a secondary air pipe group 121. The secondary dividing pipe 120 is divided by a long partition to form four secondary sub-dividing pipes 1200 with the same shape, which are integrally connected to the air outlet of the three-stage noise reduction subassembly. The secondary air duct group 121 includes two sub-air duct groups, which are a first secondary air duct group 1210 and a second secondary air duct group 1211, respectively. The first secondary sub-air duct group 1210 includes a first secondary short pipe 12100 and a first secondary long pipe 12101, and the second secondary sub-air duct group 1211 includes a second secondary short pipe 12110 and a second secondary long pipe. 12111. The first secondary sub-air duct group 1210 and the second secondary sub-air duct group 1211 are both connected to the air outlet of the secondary sub-dividing pipe 1200. The length difference between the first short second tube 12100 and the first long second tube 12101 is set to an odd multiple of the half-wavelength of the sound wave, and the length difference between the second short second tube 12110 and the second long second tube 12111 is set to the half-wave length of the sound wave Preferably, the odd multiples of, are set to be equal to the half-wavelength of the acoustic wave, where the acoustic wave wavelength is related to the noise frequency output from the three-stage noise reduction air duct subassembly 13. For the secondary noise reduction air duct subassembly 12, the noise source is the air outlet of the tertiary noise reduction air duct subassembly 13, so the noise reduction is required for the first secondary air duct group 1210 and the second secondary air duct group 1211 The noise frequency is the same, so the lengths of the first short second tube 12100 and the second short tube 12110 can be the same, and the lengths of the first long second tube 12101 and the second long second tube 12111 can be the same, that is, the length difference is the same . The secondary dividing pipe 120 is connected with the tertiary air duct group 131 in the tertiary noise reduction air duct sub-assembly 13 in the form of plug or flange connection, and the secondary duct group 121 and the primary dividing pipe 110 are connected by plug connection or flange connection. And other ways to connect. In order to enhance the connection stability, a short baffle can also be provided in the secondary dividing pipe 120.

Continuing to refer to FIG. 1, the three-stage noise reduction air duct subassembly 13 includes a three-stage dividing pipe 130 and a three-stage air pipe group 131. The three-stage dividing pipe 130 is divided by a long partition to form eight three-stage sub-dividing pipes 1300 with the same shape. The three-stage dividing pipe 130 is connected to the air outlet of the air duct machine. The downstream of the tertiary dividing pipe 130 is connected to the tertiary air duct group 131. The tertiary air duct group 131 includes 4 sub duct groups, namely the first tertiary air duct group 1310 and the second tertiary air duct group 1311. The third and third-level sub-air duct group (not marked) and the fourth and third-level sub-air duct group (not marked). Taking the first three-stage sub-air duct group 1310 and the second three-stage sub-air duct group 1311 as examples, the first three-stage sub-air duct group 1310 includes the first three-stage short pipe 13100 and the first three-stage long pipe 13101. The second and third-stage sub-air duct group 1311 includes a second and third-stage short pipe 13110 and a second and third-stage long pipe 13111. The first three-stage sub-air pipe group 1310 and the second three-stage sub-air pipe group 1311 are both connected to the air outlet of the three-stage sub-dividing pipe 1300. The length difference between the first tertiary short tube 13100 and the first tertiary long tube 13101 is set to an odd multiple of the half-wavelength of the sound wave, and the length difference between the second tertiary short tube 13110 and the second tertiary long tube 13111 is set to the half-wavelength sound wave Odd multiples of, preferably, are set to be equal to the half-wavelength of the sound wave, where the sound wave is related to the frequency of the noise output from the air outlet of the air duct machine. The length of the first three-stage short pipe 13100 and the second three-stage short pipe 13110 may be the same, and the length of the first three-stage long pipe 13101 and the second three-stage long pipe 13111 may be the same. The three-stage dividing pipe 130 and the air outlet of the air duct machine are connected by plug-in or flange connection, and the three-stage air pipe group 131 and the second-stage dividing pipe 120 are connected by plug-in connection or flange connection.

In order to ensure that the sound waves do not have large reflections, interference, etc. in each wind pipe, each wind pipe should not be bent locally and greatly. Therefore, the bending of the center line of each long pipe and short pipe in this embodiment The angle is maintained at a state greater than or equal to 120°, so as to ensure the noise reduction effect of the noise reduction component.

The noise reduction air duct assembly for air duct machines provided by the present invention uses a dividing tube and a plurality of air ducts to construct a multi-stage noise reduction air duct sub-assembly. The length difference is set equal to an odd multiple of the half-wavelength of the input noise sound wave, so that the noise reduction air duct sub-components of different levels can be used to reduce the noise of different frequencies, and realize the noise in the wider frequency range generated by the air duct machine. Targeted noise reduction processing greatly reduces the noise at the air outlet of the air duct machine. The noise reduction principle is achieved by using the interference silencing principle of sound waves, so that the noise reduction air duct assembly of the present invention has a simple structure, convenient installation, and no need for correction. The internal structure of the air duct machine is modified, and the noise reduction air duct component can be directly connected to the air outlet of the air duct machine during use. It is also applicable to the performance upgrade and transformation of the existing air duct machine, and the applicability is more powerful. In addition, the noise reduction air duct components can be customized for different noise frequencies to meet the individual needs of users, thereby greatly improving the user experience.

The design method of the noise reduction air duct assembly for the air duct machine provided by the present invention will be described in detail below in conjunction with FIG. 1 and FIG. 2.

In this embodiment, the design method of the noise reduction air duct assembly includes:

S10. Obtain at least one effective silencing frequency at the air outlet of the air duct machine.

Specifically, the effective silencing frequency can be obtained in the following manner:

S100. Detect the noise information at the air outlet of the air duct machine within a range of 0.1m-1m from the geometric center point of the air outlet of the air duct machine. In the detection process, a microphone is used to collect noise information. The microphone is placed within 0.1m-1m from the air outlet of the air duct machine, and is directly opposite to the geometric center of the air outlet.

S101. Obtain a 1/3 octave frequency spectrum of the noise information. After the noise information is collected, the noise information is processed, such as de-interference, filtering, etc., to obtain the 1/3 octave frequency spectrum of the noise information, and the obtained 1/3 octave frequency spectrum is shown in Figure 2. . In the 1/3 octave frequency spectrum, the abscissa is the noise frequency (frequency range of 100Hz-4000Hz), and the ordinate is the corresponding sound pressure level.

S102: Determine the maximum sound pressure level based on the 1/3 octave frequency spectrum. Find the largest ordinate in the 1/3 octave frequency spectrum is the maximum sound pressure level, as shown in Figure 2, the maximum sound pressure level is 39.8dB.

S103: Determine a minimum sound pressure level based on the maximum sound pressure level and a preset sound pressure level threshold, and define each sound pressure level greater than or equal to the minimum sound pressure level as an effective sound pressure level. The range of the preset sound pressure level threshold is 4dB-10dB, preferably 6dB. The minimum sound pressure level is equal to the difference between the maximum sound pressure level and the preset sound pressure level threshold. In this embodiment, the preset sound pressure level threshold is 8.9dB, and a horizontal line is drawn at a position lower than the maximum sound pressure level of 8.9dB to obtain the minimum sound pressure level, which is located between the maximum sound pressure level and the minimum sound pressure level. All sound pressure levels are effective sound pressure levels.

S104. Obtain each frequency corresponding to the effective sound pressure level. In order to facilitate the subsequent design of the air duct, further, before the step of obtaining each frequency corresponding to the effective sound pressure level, the effective sound pressure level is sorted in descending order. Referring to Figure 2 and Table 1, the statistics are as follows:

Table 1

Frequency (Hz)	Sound pressure level (dB(A))	ΔL(m)
1000	39.8	0.17
2000	39	0.09
1250	38.2	0.14
800	38.1	0.21
630	37.8	0.27
1600	37.4	0.11
400	35.5	0.43
2500	34.6	0.07
500	34.4	0.34
315	33.9	0.54

S105. Filter each frequency based on the cross-sectional size of the air outlet of the air duct machine to obtain at least one effective noise reduction frequency at the air outlet of the air duct machine. _{Specifically, first calculate the lowest effective silencing frequency f min} according to the cross-sectional size of the air outlet of the air duct machine, and the formula for calculating the lowest effective silencing frequency f _min is as follows:

f _min ＝0.85*c/L

Among them, c is the speed of sound, L is the length of the air outlet of the air duct machine, and 0.85 is an empirical value, which is obtained through experiments. The propagation speed of sound waves in the air is 340m/s. For example, L = 0.8m embodiment of the present embodiment, the f _min = 361.25Hz, i.e. when the noise frequency is lower than poor noise reduction effect when 361.25Hz air duct assembly, i.e. not in Table 1 of the 315Hz frequency noise After processing the data in Table 1, the final effective silencing frequency is 9 sets of data above 315Hz after the secondary screening of the data.

S20: Determine the number of stages of the noise reduction air duct sub-components included in the noise reduction air duct component based on the effective noise reduction frequency. Specifically, the number of stages of the noise reduction air duct sub-assembly included in the noise reduction air duct assembly is also related to the installation space of the air duct. Preferably, when the installation space permits, the noise reduction air duct sub-assembly included in the noise reduction air duct assembly The number of stages is set to be the same as the number of effective muffler frequencies. 2 and Table 1, it is preferable to set the number of stages to 9 levels, so that the corresponding noise frequencies with higher sound pressure levels listed in Table 1 can be subjected to noise reduction processing. The noise reduction air duct sub-components range from ninth level to the primary level. The ninth level is used to reduce the highest frequency noise, and the primary level is used to reduce the lowest frequency noise. It is understandable that other corresponding methods are also possible, such as nine levels for reducing the noise corresponding to the maximum sound pressure level, and the primary level for reducing the noise corresponding to the minimum sound pressure level, and so on.

If limited by the installation space and other conditions, it is impossible to design a sufficient number of noise reduction air duct sub-components, you can classify the sorted frequencies, or you can classify them according to the sound pressure level, and select one of the levels or Design at certain frequencies.

S30. Calculate the cross-sectional size of the dividing pipe in the noise reduction air duct subassembly and the number of sub-dividing pipes contained in the dividing pipe based on the cross-sectional size of the air outlet of the air duct machine and the number of stages of the noise reduction air duct subassembly.

Specifically, the cross-sectional size of the partition pipe is set to be the same as the cross-sectional size of the air outlet of the air duct machine.

According to formula (1), calculate the number of sub-dividing pipes contained in the dividing pipe:

M=2 ^N (1);

Among them, M is the number of sub-dividing pipes included in the dividing pipe, N is the number of stages corresponding to the noise reduction air duct sub-assembly, and N is a positive integer. For example, in this embodiment, the total number of stages of the noise reduction air duct subassembly is three, the number of sub-dividing tubes in the primary dividing tube is 2, and the number of stages N is 1, and the number of secondary sub-dividing tubes in the secondary dividing tube is 4. , The number of stages N is 2,; the number of three-stage sub-dividing tubes in the three-stage dividing tube is 8, and the number of stages N is 3.

S40: Calculate the length difference between the long pipe and the short pipe in the noise reduction air duct subassembly based on the effective noise reduction frequency corresponding to the noise reduction air duct subassembly.

Specifically, calculate the length difference between the long tube and the short tube according to formula (2):

ΔL=(c/2f)*n (2);

Among them, ΔL is the length difference between the long tube and the short tube; f is the effective muffling frequency; c is the speed of sound; n is a positive odd number.

For example, referring to Table 1, when f=1000Hz and n=1, ΔL=340/(2*1000)=0.17m, then the length difference between the long pipe and the short pipe in the noise reduction air duct sub-assembly of this level is 0.17m.

Finally, after determining the number of stages of the noise reduction air duct sub-assembly, the size and quantity of the dividing pipes, long pipes, and short pipes of the noise reduction air duct sub-assemblies at all levels, the noise reduction air duct assembly can be installed and connected to the air duct. The air outlet of the pipe machine has a noise reduction effect.

So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims (10)

1. A noise reduction air duct assembly for a duct machine, characterized in that the noise reduction air duct assembly includes at least one level of noise reduction air duct subassembly, and the noise reduction air duct subassembly includes:

   A dividing pipe connected to the air outlet of the air duct machine or the air outlet of the previous-stage noise reduction air duct subassembly, and 2N sub-dividing pipes are formed in the dividing pipe;

   The air duct group includes N sub-air duct groups, the sub-air duct group is connected to the air outlet of the sub-dividing pipe, the sub-air duct group includes parallel short pipes and long pipes, the short pipes and The length difference of the long tube is set to an odd multiple of the half wavelength of the sound wave, where N is a positive integer.
2. The noise reduction air duct assembly for a wind pipe machine according to claim 1, wherein the difference in length between the short pipe and the long pipe is set equal to a half-wavelength of a sound wave.
3. The noise reduction air duct assembly for an air duct machine according to claim 1, wherein the bending angle of the center line of the short pipe and/or the long pipe is greater than or equal to 120°.
4. A design method of a noise reduction air duct assembly for a duct machine, characterized in that the design method of the noise reduction air duct assembly includes:

   Acquiring at least one effective muffling frequency at the air outlet of the air duct machine;

   Determining the number of stages of noise reduction air duct sub-components included in the noise reduction air duct component based on the effective noise cancellation frequency;

   Calculate the cross-sectional size of the dividing tube in the noise reduction air duct subassembly and the number of sub-dividing tubes contained in the dividing tube based on the cross-sectional size of the air outlet of the air duct machine and the number of stages of the noise reduction air duct subassembly ；

   The length difference between the long pipe and the short pipe in the noise reduction air duct subassembly is calculated based on the effective noise reduction frequency corresponding to the noise reduction air duct subassembly.
5. The design method of the noise reduction air duct assembly for the air duct machine according to claim 4, wherein the step of "obtaining at least one effective silencing frequency at the air outlet of the air duct machine" specifically comprises:

   Detecting noise information at the air outlet of the air duct machine within a range of 0.1 m-1 m from the geometric center point of the air outlet of the air duct machine;

   Acquiring a 1/3 octave frequency spectrum of the noise information;

   Determining the maximum sound pressure level based on the 1/3 octave frequency spectrum;

   Determine a minimum sound pressure level based on the maximum sound pressure level and a preset sound pressure level threshold, and define each sound pressure level greater than or equal to the minimum sound pressure level as an effective sound pressure level;

   Acquiring each frequency corresponding to the effective sound pressure level;

   The respective frequencies are screened based on the cross-sectional size of the air outlet of the air duct machine to obtain at least one effective silencing frequency at the air outlet of the air duct machine.
6. The method for designing a noise reduction air duct assembly for a duct machine according to claim 5, wherein the preset sound pressure level threshold is in the range of 4dB-10dB, and the minimum sound pressure level is equal to the The difference between the maximum sound pressure level and the preset sound pressure level threshold.
7. The design method of a noise reduction air duct assembly for a duct machine according to claim 5, wherein the step of "obtaining at least one effective noise reduction frequency at the air outlet of the duct machine" further comprises:

   Before the step of obtaining the frequencies corresponding to the effective sound pressure levels, the effective sound pressure levels are sorted in descending order.
8. The method for designing a noise reduction air duct assembly for a duct machine according to claim 4, characterized in that "determining the value of the noise reduction air duct sub-assembly included in the noise reduction air duct assembly based on the effective noise cancellation frequency The steps of the “level number” specifically include:

   The number of stages of the noise reduction air duct sub-components included in the noise reduction air duct component is set to be the same as the number of the effective noise reduction frequencies.
9. The design method of the noise reduction air duct assembly for the air duct machine according to claim 4, characterized in that "based on the cross-sectional size of the air outlet of the air duct machine and the number of stages of the noise reduction air duct subassembly The step of calculating the cross-sectional size of the dividing tube in the noise reduction air duct sub-assembly and the number of sub-dividing tubes contained in the dividing tube specifically includes:

   Setting the cross-sectional size of the dividing pipe to be the same as the cross-sectional size of the air outlet of the air duct machine;

   Calculate the number of sub-dividing tubes included in the dividing tube according to formula (1):

   M=2 ^N (1);

   Among them, M is the number of sub-dividing pipes included in the dividing pipe, N is the number of stages corresponding to the noise reduction air duct sub-assembly, and N is a positive integer.
10. The method for designing a noise reduction air duct assembly for a duct machine according to claim 4, characterized in that "calculate the noise reduction air duct based on the effective noise reduction frequency corresponding to the noise reduction air duct subassembly The steps of "the length difference between the long tube and the short tube in the assembly" specifically include:

    Calculate the length difference between the long pipe and the short pipe according to formula (2):

    ΔL=(c/2f)*n (2);

    Among them, ΔL is the length difference between the long tube and the short tube; f is the effective muffling frequency; c is the speed of sound; n is a positive odd number.

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