Multi-fan blade angle non-uniform distribution structure for reducing beat vibration noise

Abstract

The invention relates to a multi-fan blade angle non-uniform distribution structure for reducing beat vibration noise, and aims to solve the technical problem that the beat vibration noise is difficult to reduce through scientific and accurate blade number setting and blade angle non-uniform distribution design of existing similar products. Blades at a fan of the structure are arranged at non-uniform angles by taking a shaft core in a hub as a center, and the non-uniform angles are circular angles formed by the blades which are arranged at non-uniform angles by taking the shaft core in the hub as the center; the method is characterized in that the blades modulate the real-time rotating speed of each fan through a control center so as to avoid frequency discretization or set the number of the blades according to discrete noise frequency distance, and finally the non-uniform distribution angles between the blades are obtained through blade angle non-uniform distribution modulation; the control center is a control module which comprises a control chip and a signal conversion input and output port and is used for data calculation and processing. When the mode B is selected in the real-time regulation and control stage of the blade angle non-uniform distribution modulation, a sorting and interval greedy algorithm is adopted.

Description

Technical Field

[0001] The invention relates to a heat dissipation fan, which is a structure with unevenly distributed angles of multiple fan blades to reduce flapping noise. Background Art

[0002] Currently, cooling fans are often integrated into multiple fans in practical applications due to insufficient air volume per unit. However, when multiple fans are in operation, the speeds of the fans are generally controlled at the same speed. However, in actual operation, the speeds of the fans may vary slightly due to factors such as load variations, manufacturing non-uniformity, independent control differences, and lack of unified control feedback. When the speed differences are within a certain range, multiple close characteristic frequency noises, i.e., beat noise, will be generated. The mechanism of the above-mentioned beat noise generation is as follows: When multiple fans are in operation, the speed differences of the fans lead to the superposition of characteristic frequency noises, forming a beat frequency phenomenon with a frequency difference of Δf = Z(n1-n2) / 60 (Z is the equivalent number of blades). The human ear is most sensitive to the difference frequency of 3-5Hz. When Δf is less than 15Hz, a clear low-frequency pulsating noise will be perceived. When Δf is greater than 15Hz, the beat frequency is converted into high-frequency continuous noise, and the sensitivity of the human ear is reduced. Some existing cooling fan products utilize a non-uniform blade distribution design, such as the Chinese patent application number 202410222574.7, published on May 28, 2024, titled "A Design Method for a Fan with Non-Uniform Blades Based on Phase Interference." However, the control method differs significantly. Rather than being designed to reduce beat noise, it only addresses the non-uniform blade distribution and does not involve feedback control of speed differences. Summary of the Invention

[0003] To overcome these shortcomings, the present invention aims to provide a multi-fan structure with uneven blade angle distribution to reduce flapping noise. This solves the technical problem of existing similar products, which are difficult to achieve by scientifically and accurately setting the number of blades and designing uneven blade angle distribution to reduce flapping noise. This objective is achieved through the following technical solutions.

[0004] A structure for reducing flapping noise with non-uniformly distributed blade angles of multiple fans, wherein a plurality of blades are provided on the outer diameter of the hub of the fan of the structure, and the blades are arranged at non-uniform angles with the shaft core in the hub as the center, and the non-uniform angles are circular angles at which the blades are arranged with the shaft core in the hub as the center; the structure is characterized in that the blades modulate the real-time rotation speed of each fan through a control center to avoid frequency discreteness or discrete noise frequency intervals, set the number of blades, and finally obtain the non-uniform angles between the blades through non-uniform blade angle modulation; the control center is a control module that includes a control chip, a signal conversion input and output port, and is used for data calculation and processing.

[0005] The blades are modulated by the control center to control the real-time speed of each fan to avoid frequency dispersion, so that the difference between the maximum speed and the minimum speed is lower than the value at which a significant beat frequency can be separated. Where z is the equivalent number of blades, which is the number of blades that has the greatest impact on the beat noise.

[0006] The blades are modulated by the control center to adjust the real-time speed of each fan to discrete noise frequency, so that the minimum difference between any two rotation speeds of multiple fans is higher than a certain value. Make the discretized noise sufficient " Discrete", where z is the equivalent number of blades, and the number of blades that has the greatest impact on the beat noise is taken.

[0007] The blade angle is non-uniformly modulated. Select n of the multiple wind turbines (N) for blade angle non-uniform modulation, n < 0.5N, and the modulation is based on the blade distribution difference angle changing according to sine wave / square wave / other rules, where the maximum modulation angle of the blade is ≤ 20% of the single blade center angle. Destroys harmonic phase coherence and reduces peaks with discrete noise.

[0008] The implementation steps of the structure are as follows: 1) Initialization phase, determine the equivalent number of blades z and the working mode; 2) Real-time control phase, select mode A, calculate the current speed range Δn through the control center max If the speed exceeds the limit, a speed change instruction is sent to one or both fans with the largest speed deviation to adjust the speed difference to Select mode B and build a speed difference matrix through the control center If exists Then, the speed data set is sorted and the interval greedy algorithm is used to select the minimum speed that meets the conditions to adjust the speed, and the maximum or minimum speed is determined to change the target speed; 3) In the blade angle non-uniform modulation stage, the blade angle non-uniform modulation is performed.

[0009] The specific steps of the sorting and interval greedy algorithm for selecting mode B in the real-time control phase of step 2) are as follows:

[0010] Sort the set to get the array a[0], a[1], ..., a[n-1] in ascending order;

[0011] Initialize the adjusted array b[0]=a[0], and the number of adjustments count=0;

[0012] Traverse from i=1 to n-1:

[0013] a. Calculate the difference between the current element a[i] and the previous adjusted element b[i-1]: delta = a[i] - b[i-1];

[0014] b. If delta>X, keep a[i], that is, b[i]=a[i];

[0015] c. Otherwise, set b[i] to b[i-1]+X+ε, where ε is a small positive number such as 0.001, and increase count;

[0016] Finally, the difference between all adjacent elements is greater than X, so the difference between any two elements in the entire set is greater than X, and the number of adjustments is count;

[0017] In this way, the number of adjustments count is the minimum number of adjustments required.

[0018] The present invention has a reasonable structural design, scientific and precise implementation steps, and is convenient for setting the number of blades and uneven angles. It is suitable for use as a structure for reducing flapping noise by unevenly distributing blade angles in multiple fans, and is a further improvement of similar products. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the spectrum of the beat interval of the present invention.

[0020] Figure 2 It is a schematic diagram of the spectrum change of the speed regulation of the present invention.

[0021] Figure 3 This is a curve diagram showing the effect of the modulation angle change on the blade center angle distribution of the present invention.

[0022] Figure 4 It is a schematic diagram of setting the number of blades and the blade non-uniform angle after blade angle non-uniform distribution modulation of the present invention. Implementation Method

[0023] Now, the structure and use of the present invention will be further described in conjunction with the accompanying drawings. Figures 1-4 As shown in the figure, the structure is based on the beat vibration problem of multiple wind turbines. The speed of multiple wind turbines is adjusted to be close to the same or with a certain difference through a linkage closed-loop control strategy, so that the peak noise is concentrated on the fundamental frequency or multiple peak noise frequencies with a difference higher than the human ear's distinguishable range, or the noise peaks of the discrete fundamental frequency and nearby related frequencies, thereby reducing the beat vibration noise.

[0024] The fan of the above-mentioned structure is provided with a plurality of blades on the outer diameter of the hub, and the blades are arranged at non-uniform angles with the shaft core in the hub as the center, and the non-uniform angles are circular angles at which the blades are arranged with the shaft core in the hub as the center; the blades modulate the real-time speed of each fan through the control center to avoid frequency discreteness or discrete noise frequency interval, set the number of blades, and finally obtain the non-uniform angles between the blades through the non-uniform modulation of the blade angles; the control center is a control module including a control chip, a signal conversion input and output port, and is used for data calculation and processing.

[0025] The specific innovations of this structure are as follows:

[0026] Method A modulates the real-time feedback speed of multiple wind turbines through the control center to avoid frequency dispersion, so that the difference between the maximum speed and the minimum speed is lower than the value at which a significant beat frequency can be separated. Where z is the equivalent number of blades. The number of blades that has the greatest impact on the beat noise is taken to improve the beat noise.

[0027] Method B modulates the real-time speed of each fan through the control center to discrete the noise frequency, so that the minimum difference between any two rotating speeds of multiple fans is higher than a certain value. Make the discretized noise sufficiently discrete, where z is the equivalent number of blades, and take the number of blades that has the greatest impact on the beat noise, so as to improve the beat noise (such as Figure 1 、 2 shown).

[0028] Furthermore, n of the multiple wind turbines (N) are selected for blade angle non-uniform modulation, n < 0.5N, and the modulation is based on the blade distribution difference angle changing according to sine wave / square wave / other rules, where the maximum modulation angle of the blade is ≤ 20% of the single blade center angle The harmonic phase coherence is destroyed to reduce the peak value with discrete noise, thereby weakening the beat noise.

[0029] 1. Initialization stage: determine the equivalent number of blades z and the working mode (mode A / mode B).

[0030] 2. Real-time control stage:

[0031] Mode A: Calculate the current speed difference Δn through the control center max If the speed exceeds the limit, a speed change instruction is sent to one or both fans with the largest speed deviation to adjust the speed difference to Within.

[0032] Mode B: The speed difference matrix D = [|ni-nj|] is constructed by the control center. If there is Then, the speed data set is sorted and the interval greedy algorithm is used to select the minimum speed that meets the conditions to adjust the speed, and the maximum or minimum speed is determined to change the target speed.

[0033] The following is an example of the method concept (the rotation speed value set is an array, and X is defined as 900 / z, which can be applied to this embodiment).

[0034] {

[0035] Sort the set to get the array a[0], a[1], ..., a[n-1] in ascending order;

[0036] Initialize the adjusted array b[0]=a[0], and the number of adjustments count=0;

[0037] Traverse from i=1 to n-1:

[0038] a. Calculate the difference between the current element a[i] and the previous adjusted element b[i-1]: delta = a[i] - b[i-1];

[0039] b. If delta>X, keep a[i], that is, b[i]=a[i];

[0040] c. Otherwise, set b[i] to b[i-1]+X+ε, where ε is a small positive number such as 0.001, and increase count;

[0041] Finally, the difference between all adjacent elements is greater than X, so the difference between any two elements in the entire set is greater than X, and the number of adjustments is count;

[0042] In this way, the number of adjustments count is the minimum number of adjustments required.

[0043] }

[0044] 3. Blade Angle Non-Uniform Distribution Modulation Stage:

[0045] Select n wind turbines from multiple wind turbines (N) to perform non-uniform blade angle modulation, n < 0.5N, and modulate the blade distribution difference angle according to sine wave / square wave / other rules, where the maximum blade modulation angle is ≤ 20% of the blade distribution difference angle Destroy the harmonic phase consistency and reduce the peak value with discrete noise, thereby reducing the beat noise (such as Figure 3 、 4 shown).

[0046] To sum up, there are two main control methods for this structure, one is speed difference feedback control, and the other is uneven distribution of blades, which serves as an auxiliary method. Among them, one is the speed control technology, and the other is the discrete blade form in the structure. The two are integrated or implemented separately to achieve uneven setting of the number of blades and blade angles.

Claims

1. A structure for reducing flapping noise by distributing blades at uneven angles on multiple fan blades. The fan has a plurality of blades disposed on the outer diameter of the fan hub. The blades are disposed at uneven angles with respect to the shaft core within the hub. The uneven angles are circular angles at which the blades are unevenly distributed with respect to the shaft core within the hub. The blades are modulated by the control center to adjust the real-time rotation speed of each fan to avoid frequency discreteness or discrete noise frequency interval, set the number of blades, and finally obtain the non-uniform angles between the blades through the non-uniform modulation of the blade angles; the control center is a control module that includes a control chip, signal conversion input and output ports, and is used for data calculation and processing.

2. The structure for reducing beat noise by unevenly distributing blade angles of multiple fans according to claim 1 is characterized in that The blades are modulated by the control center to the real-time speed of each fan to avoid frequency dispersion, so that the difference between the maximum speed and the minimum speed is lower than the value at which a significant beat frequency can be separated. Where z is the equivalent number of blades, which is the number of blades that has the greatest impact on the beat noise.

3. The structure for reducing beat noise by unevenly distributing blade angles of multiple fans according to claim 1 is characterized in that The blades are modulated by the control center to adjust the real-time speed of each fan to discrete noise frequency, so that the minimum difference between any two rotation speeds of multiple fans is higher than a certain value. Make the discretized noise sufficiently discrete, where z is the equivalent number of blades, and take the number of blades that has the greatest impact on the beat noise.

4. The structure for reducing beat noise by unevenly distributing blade angles of multiple fans according to claim 1 is characterized in that The blade angle is non-uniformly modulated. Select n wind turbines for blade angle non-uniform modulation. n < 0.5N. The modulation changes the blade distribution difference angle according to sine wave / square wave / other rules. The maximum modulation angle of the blade is ≤ 20% of the center angle of a single blade. Destroys harmonic phase coherence and reduces peaks with discrete noise.

5. The structure for reducing beat noise by unevenly distributing blade angles of multiple wind turbines according to claim 4 is characterized in that The implementation steps of the structure are as follows: 1) Initialization phase, determine the equivalent number of blades z and determine the working mode; 2) Real-time control phase, select mode A, calculate the current speed range Δn through the control center max If the speed exceeds the limit, a speed change instruction is sent to one or both of the fans with the largest speed deviation to adjust the speed difference to Select mode B and construct the speed difference matrix D=[|ni-nj|] through the control center. If there is Then, the speed data set is sorted and the interval greedy algorithm is used to select the minimum speed that meets the conditions to adjust the speed, and the maximum or minimum speed is determined to change the target speed; 3) In the blade angle non-uniform modulation stage, the blade angle non-uniform modulation is performed.

6. The structure for reducing beat noise by unevenly distributing blade angles of multiple wind turbines according to claim 5 is characterized in that The specific details of the sorting and interval greedy algorithm for selecting mode B in step 2) real-time control are as follows: Sort the set to get the array a[0], a[1], ..., a[n-1] in ascending order; Initialize the adjusted array b[0]=a[0], and the number of adjustments count=0; Traverse from i=1 to n-1: a. Calculate the difference between the current element a[i] and the previous adjusted element b[i-1]: delta = a[i] - b[i-1]; b. If delta>X, keep a[i], that is, b[i]=a[i]; c. Otherwise, set b[i] to b[i-1]+X+ε, where ε is a small positive number such as 0.001, and increase count; Finally, the difference between all adjacent elements is greater than X, so the difference between any two elements in the entire set is greater than X, and the number of adjustments is count; In this way, the number of adjustments count is the minimum number of adjustments required.

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