A fan blade angle-adjustable cooling fan and an adjusting method thereof

Abstract

The application provides a heat dissipation fan with adjustable fan blade angle and an adjusting method thereof, which comprises a driving part, a main body frame, a rotating main body, a fan blade, a rotating shaft, an angle adjusting mechanism, a noise monitoring module and a control module; the control module can adjust the inclination angle of the fan blade and the rotating speed of the rotating shaft through the noise value Z, thereby changing the noise size in the main body frame, and the generation of high-frequency noise and low-frequency noise is inhibited, so that the heat dissipation fan can meet the silent demand in full working condition.

Description

Technical Field

[0001] This invention relates to the field of heat dissipation device technology, specifically to a cooling fan with adjustable blade angle and its adjustment method. Background Technology

[0002] During the operation of a cooling fan, when the cooling demand is high and the fan is running at high speed (usually greater than 2500 rpm), the high-speed friction between the fan blades and the airflow generates high-frequency aerodynamic noise, typically concentrated in the frequency range above 2000 Hz. At the same time, the operation of components such as the motor and bearings also generates mechanical noise, interfering with the user's work and living environment. Therefore, in order to reduce the noise generated by the fan at high speeds, without reducing the cooling capacity (with the same airflow), the fan blade angle is usually set to be larger, thereby reducing the fan speed to achieve the same cooling capacity and thus reducing noise generation. However, under low-speed operating conditions, such as when the cooling demand is not high and a stable cooling state needs to be maintained for a long time (usually less than 1500 rpm), the large-angle fan blades are prone to generating low-frequency vortex noise (mainly distributed in the frequency range below 500 Hz) due to airflow separation. Therefore, traditional cooling fans with fixed blade angles cannot suppress both high-frequency and low-frequency noise at the same time, making it difficult for the cooling fan to meet the quiet operation requirements under all operating conditions. Summary of the Invention

[0003] The purpose of this invention is to design a cooling fan with adjustable blade angle to solve the problems mentioned in the background art. To achieve the above objective, this invention provides the following technical solution: a drive component mounted on a main frame for adjusting the rotational speed of a rotating shaft; a rotating body connected to the rotating shaft; a plurality of fan blades rotatably connected to the rotating body and connected to an angle adjustment mechanism; a noise monitoring module mounted on the main frame for detecting noise from inside the main frame; and a control module mounted on the main frame and connected to the noise monitoring module. The angle adjustment mechanism is mounted on the rotating body, and both the drive component and the angle adjustment mechanism are connected to the control module. The control module adjusts the tilt angle θ of the fan blades and the rotational speed N of the rotating shaft according to the received noise value Z through the drive component and the angle adjustment mechanism.

[0004] The present invention also discloses a method for adjusting the blade angle, which is used to adjust the blade angle of the above-mentioned cooling fan. The specific adjustment method is as follows: A noise threshold Z0 is preset on the control module. When the control module is in the high-speed operating condition of the rotating shaft and the received noise value is greater than the noise threshold, while upwardly correcting the tilt angle of the fan blade, the rotational speed of the rotating shaft is downwardly corrected; when the control module is in the low-speed operating condition of the rotating shaft and the received noise value is greater than the noise threshold, while upwardly correcting the tilt angle of the fan blade, the rotational speed of the rotating shaft is downwardly corrected; wherein, a air volume detection module and a rotational speed detection module connected to the control module are further provided on the main body frame. The air volume detection module is used to detect the actual air volume Q of the fan in real time; the rotational speed detection module is used to detect the rotational speed N of the rotating shaft in real time; and a medium-speed operation range (Nmin, Nmax) is preset on the control module; when the control module identifies that N > Nmax, it is determined that the rotating shaft is in the high-speed operating condition; when the control module identifies that N < Nmin, it is determined that the rotating shaft is in the low-speed operating condition.

[0005] Further, a standard tilt angle θ0 is preset on the control module, and the tilt angle value of the fan blade is: θi = θ0 ± 15°; when the control module is in the high-speed operating condition of the rotating shaft and the received noise value is greater than the noise threshold; the control module respectively corrects θ to θ1 = θ0 + 5°, θ2 = θ0 + 10° and θ3 = θ0 + 15°. After each correction, the control module calculates the theoretical rotational speeds N1, N2 and N3 corresponding to θ1, θ2 and θ3 when Q is a fixed value through the formula Ni = Q / (θi A η k); The noise monitoring module tests the corresponding Z1, Z2 and Z3 in these three rotational modes of the fan blade, and takes the adjustment angle corresponding to the minimum value among them as the primary adjustment angle of the fan blade; Q is the air volume, k is the structure constant, A is the cross-sectional area of the air flow, and η is the aerodynamic efficiency.

[0006] Further, based on the primary adjustment angle θi, θ is respectively corrected upward and downward, that is, θ4 = θi + 2°, θ5 = θi - 2°. The control module calculates the theoretical rotational speeds N4 and N5 corresponding to θ4 and θ5. The noise monitoring module tests the corresponding Z4 and Z5 in these two rotational modes of the fan blade, and takes the angle correction direction corresponding to the minimum value among them as the secondary correction direction of the fan blade. Subsequently, with 0.5° as the correction unit, it is corrected ten times in a step-by-step cumulative form in the secondary correction direction. The noise monitoring module tests the corresponding Zi in these ten rotational modes of the fan blade. When Zi < Z0 and Zi is the minimum value, the corresponding θi and Ni are the tilt angle of the fan blade and the rotational speed of the rotating shaft after noise reduction.

[0007] Further, a standard tilt angle θ0 is preset on the control module, and the tilt angle of the fan blade takes values: θi = θ0 ± 15°; when the control module is in the low-speed operating condition of the rotating shaft and the received noise value is greater than the noise threshold, the control module respectively corrects θ to θ1 = θ0 - 5°, θ2 = θ0 - 10°, and θ3 = θ0 - 15°. After each correction, the control module calculates the theoretical speeds N1, N2, and N3 corresponding to θ1, θ2, and θ3 when Q is a fixed value through the formula Ni = Q / (θi A η k). The noise monitoring module measures the corresponding Z1, Z2, and Z3 in these three rotation modes of the fan blade, and takes the adjustment angle corresponding to the minimum value among them as the primary adjustment angle of the fan blade; Q is the air volume, k is the structural constant, A is the air flow cross-sectional area, and η is the aerodynamic efficiency.

[0008] Further, θ is corrected upward and downward respectively based on the primary adjustment angle θi, that is, θ4 = θi + 2° and θ5 = θi - 2°. The control module calculates the theoretical speeds N4 and N5 corresponding to θ4 and θ5. The noise monitoring module measures the corresponding Z4 and Z5 in these two rotation modes of the fan blade, and takes the angle correction direction corresponding to the minimum value among them as the secondary correction direction of the fan blade. Subsequently, with a correction unit of 0.5°, it is corrected ten times in a step-by-step cumulative form in the secondary correction direction. The noise monitoring module measures the corresponding Zi in these ten rotation modes of the fan blade. When Zi < Z0 and Zi is the minimum value, the corresponding θi and Ni are the tilt angle of the noise-reduced fan blade and the rotation speed of the rotating shaft.

[0009] Further, when the control module is between the low-speed and high-speed operating conditions of the rotating shaft and the received noise value is greater than the noise threshold; the control module respectively corrects θ to θ6 = θ0 - 2° and θ7 = θ0 + 2°. After each correction, the control module calculates the theoretical speeds N6 and N7 corresponding to θ6 and θ7 when Q is a fixed value; the noise monitoring module measures the corresponding Z6 and Z7 in these two rotation modes of the fan blade, and takes the angle correction direction corresponding to the minimum value among them as the correction direction of the fan blade. Subsequently, with a correction unit of 0.5°, it is corrected five times in a step-by-step cumulative form in the correction direction. The noise monitoring module measures the corresponding Zi in these five rotation modes of the fan blade. When Zi < Z0 and Zi is the minimum value, the corresponding θi and Ni are the tilt angle of the noise-reduced fan blade and the rotation speed of the rotating shaft.

[0010] Furthermore, the noise monitoring module distinguishes between aerodynamic noise and mechanical noise through spectrum analysis, and records the aerodynamic noise value as Zq and the mechanical noise value as Zj. The control module calculates the value of a=Zq / Zj in real time. If a>2, it corrects θ downwards while correcting N upwards. If 0.5≤a<0.8, it corrects θ upwards while correcting N downwards. If a<0.5, the control module determines that the fan has malfunctioned and issues a warning.

[0011] Furthermore, once the fan blade angle is adjusted, the lag time for adjusting the rotational speed of the rotating shaft is 50-100ms.

[0012] Furthermore, the main frame is equipped with an environmental noise detection module connected to the control module. This module detects environmental noise Zh and identifies the noise source, recording in real time the minimum distance L1 and relative angle θ8 from the noise source to the main frame. The fan is also equipped with a radar detection module, used to detect in real time the minimum distance L2 and relative angle θ9 from the main frame to the human body. The control module calculates the distance L3 from the noise source to the human body in real time using L1, L2, θ8, and θ9. Let g=b (Z-20log 10 L2) / (Zh-20log 10 L3), where b is a pre-input constant and b>2; when g≤1, the control module determines that the noise generated by the fan is harmless noise, and does not correct θ and N at this time; when g>1, the control module determines that the noise generated by the fan is harmful noise, and corrects θ and N accordingly to reduce Z.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The control module of the present invention can adjust the tilt angle of the fan blades and the rotation speed of the rotating shaft by adjusting the noise value Z, thereby changing the noise level inside the main frame, thereby suppressing the generation of high-frequency noise and low-frequency noise, so that the cooling fan can meet the quiet requirements when running under all operating conditions. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0016] Figure 2 This is a schematic diagram of the internal structure of the rotating main body.

[0017] The components include: 1. Rotating main body; 2. Fan blades; 3. Drive motor; 4. First bevel gear; 5. Second bevel gear; 6. Reducer; 7. Main frame. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structure, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0019] Example: Please refer to Figure 1-2 A cooling fan with adjustable blade angle includes a drive unit mounted on a main frame 7 for adjusting the rotational speed of a rotating shaft, a rotating body 1 connected to the rotating shaft, a plurality of fan blades 2 rotatably connected to the rotating body 1 and connected to an angle adjustment mechanism, a noise monitoring module mounted on the main frame 7 for detecting noise from inside the main frame 7, and a control module mounted on the main frame 7 and connected to the noise monitoring module. The angle adjustment mechanism is mounted on the rotating body 1, and both the drive unit and the angle adjustment mechanism are connected to the control module. The control module adjusts the tilt angle θ of the fan blades 2 and the rotational speed N of the rotating shaft according to the received noise value Z through the drive unit and the angle adjustment mechanism. The drive unit can be a servo motor. Therefore, the control module in this invention can adjust the tilt angle of the fan blades 2 and the rotational speed of the rotating shaft by adjusting the noise value Z inside the main frame 7, thereby changing the noise level inside the main frame 7 and suppressing the generation of high-frequency and low-frequency noise, so that the cooling fan can meet the quiet operation requirements under all operating conditions.

[0020] The angle adjustment mechanism includes a drive motor 3 fixed to the rotating body 1, a reducer 6 located inside the rotating body 1 and connected to the drive motor 3 at its input end, a first bevel gear 4 fixed to the end of the fan blade 2 located inside the rotating body 1, and a second bevel gear 5 connected to the output end of the reducer 6 and rotatably connected inside the rotating body 1. Several first bevel gears 4 mesh with the second bevel gears 5. When the drive motor 3 drives the second bevel gear 5 to rotate, the first bevel gear 4 will rotate, thereby driving the fan blade 2 to rotate, thus realizing the adjustment of the tilt angle of the fan blade 2. In addition, the tilt angle θ of the fan blade 2 refers to the angle between the plane of the fan blade 2 and the plane of rotation of the fan. The size of this angle affects the aerodynamic performance of the fan. When the tilt angle θ increases, the direction of the force that the fan blade 2 exerts on the air changes, causing the air to be accelerated and discharged in a direction further away from the plane of rotation. At the same rotation speed, theoretically, the air volume can be increased. Conversely, when the tilt angle θ decreases, the pushing effect of the fan blade 2 on the air weakens, and the air volume will decrease.

[0021] The present invention also discloses a method for adjusting the angle of the fan blade, which is used to adjust the angle of the fan blade in the above-mentioned cooling fan. The specific adjustment method is as follows: A noise threshold Z0 is preset on the control module. When the rotating shaft is in a high-speed operating condition and the received noise value is greater than the noise threshold, while upwardly correcting the tilt angle of the fan blade 2, the rotational speed of the rotating shaft is downwardly corrected, so as to achieve the control of high-frequency noise (although in the high-speed operating condition, noise reduction can also be achieved by increasing the rotational speed and decreasing the tilt angle, but in the experimental process, it is found that although decreasing the tilt angle can delay the airflow separation and theoretically the low-frequency noise may decrease, it will cause a sharp increase in high-frequency noise, far exceeding the low-frequency improvement, and cannot effectively control the high-frequency noise. Therefore, the total noise sound pressure level may deteriorate. Therefore, in this application, for the high-speed operating condition, the method of increasing the tilt angle of the fan blade 2 is adopted, while for the low-speed operating condition, since the rotational speed is low, it is better to adopt the form of decreasing the tilt angle); When the rotating shaft is in a low-speed operating condition and the received noise value is greater than the noise threshold, while upwardly correcting the tilt angle of the fan blade 2, the rotational speed of the rotating shaft is downwardly corrected, so as to achieve the control of low-frequency noise; In addition, a air volume detection module and a rotational speed detection module connected to the control module are further provided on the main body frame 7. The air volume detection module is used to detect the actual air volume Q of the fan in real time; The rotational speed detection module is used to detect the rotational speed N of the rotating shaft in real time; And a medium-speed operation range (Nmin, Nmax) is preset on the control module; When the control module identifies that N > Nmax, it is determined that the rotating shaft is in a high-speed operating condition; When the control module identifies that N < Nmin, it is determined that the rotating shaft is in a low-speed operating condition; Usually, Nmin = 1500 rpm and Nmax = 2500 rpm;

[0022] Therefore, in the present invention, when the control module identifies that Z > Z0 and N > Nmax, the control module determines that the high-frequency noise generated by the fan blade 2 and the airflow reaches the situation of interfering with the user's work and life. At this time, after the control module records the air volume at this time as Q1, while upwardly correcting θ and downwardly correcting N until Z < Z0, thereby eliminating the influence brought by the high-frequency noise; On the contrary, when the control module identifies that Z > Z0 and N < Nmin, the control module determines that the low-frequency eddy current noise generated by the fan blade 2 and the airflow reaches the situation of interfering with the user's work and life. At this time, after the control module records the air volume at this time as Q2, while downwardly correcting θ and upwardly correcting N until Z < Z0, thereby eliminating the influence brought by the low-frequency noise; Therefore, in the present invention, the fan blade 2 with adjustable angle is provided, which can suppress both high-frequency noise and low-frequency noise, so that the cooling fan can meet the silent requirement during the full operating condition.

[0023] Furthermore, this application also discloses the specific correction process of the control module during the correction process, which greatly saves correction time; that is, a standard tilt angle θ0 is preset on the control module, so the actual tilt angle θi of the fan blade 2 is θi = θ0 ± 15°; where θ0 = 30°, so the value of θi is between 15° and 45°, which is a reasonable angle range for common cooling fans; when the control module identifies Z > Z0 and N > Nmax; at this time, the control module determines that the high-frequency noise generated by the fan blade 2 and the airflow has reached the point of interfering with the user's work and life. Therefore, the control module corrects θ to θ1 = 35°, θ2 = 40° and θ3 = 45° respectively. After each correction, the control module uses the formula Ni = Q / (θi) A η k) Calculate the theoretical rotational speeds N1, N2, and N3 corresponding to θ1, θ2, and θ3 when Q is constant; the above formulas are derived from the quantitative relationship between rotational speed and angle; at this time, Q=Q1. Since k is the structural constant, A is the airflow cross-sectional area, and η is the aerodynamic efficiency, all are determined by the structure of fan blade 2. Users can determine these based on their existing fan structure, without further restrictions. The noise monitoring module tests the corresponding Z1, Z2, and Z3 in the following rotation modes: fan blade 2 tilt angle is 35°, rotational shaft speed is N1; tilt angle is 40°, rotational shaft speed is N2; tilt angle is 45°, rotational shaft speed is N3. The minimum value is taken as the initial adjustment angle of fan blade 2. Thus, it can be preliminarily determined that the θ value corresponding to the actual noise reduction completion will be near the initial adjustment angle.

[0024] Subsequently, taking the primary adjustment angle θi as a reference, θ is corrected upward and downward respectively, that is, θ4 = θi + 2°, θ5 = θi - 2°. The control module calculates the theoretical rotational speeds N4 and N5 corresponding to θ4 and θ5. The noise monitoring module measures the corresponding Z4 and Z5 in these two rotation modes of the fan blade 2. Therefore, after upward and downward corrections of 2°, by determining which of the corrected noises is closer to the noise before correction, it can be determined on which side of the primary adjustment angle the minimum noise after adjustment is actually located. At this time, the angle correction direction corresponding to the minimum value of Z4 and Z5 can be taken as the secondary correction direction of the fan blade 2. Subsequently, with a correction unit of 0.5°, it is corrected ten times in a step-by-step cumulative form in the secondary correction direction. The noise monitoring module measures the corresponding Zi in these ten rotation modes of the fan blade 2. When Zi < Z0 and Zi is the minimum value, the corresponding θi and Ni are the inclination angle of the fan blade 2 and the rotational speed of the rotation axis after noise reduction, thus completing the noise reduction adjustment without affecting its air output and ensuring its heat dissipation capacity. At the same time, through the above method, compared with the conventional adjustment process gradually increasing from 30° to 45°, the adjustment in the present invention is faster and more efficient while ensuring accuracy. If during this process, there is no situation where Zi < Z0, the primary adjustment angle is modified to other angles and carried out again until Zi < Z0 is found. If there is also no situation where Zi < Z0 in the correction process based on the two changed primary adjustment angles, the inclination angle of the fan blade 2 and the rotational speed of the rotation axis corresponding to the minimum Zi among all detection results are taken as the current optimal fan startup parameters.

[0025] Similarly, for the case of generating low-frequency eddy current noise, it is the same as above; when the control module identifies that Z > Z0 and N < Nmin; the control module corrects θ to θ1 = 25°, θ2 = 20° and θ3 = 15° respectively. After each correction, the control module calculates Ni = Q / (θi A η k) Calculate the theoretical speeds N1, N2, and N3 corresponding to θ1, θ2, and θ3 when Q is a fixed value; at this time, Q = Q2, and the noise monitoring module tests the corresponding Z1, Z2, and Z3 in these three rotation modes of the fan blade 2, and takes the adjustment angle corresponding to the minimum value among them as the primary adjustment angle of the fan blade 2; subsequently, based on the primary adjustment angle θi, θ is corrected upward and downward respectively, that is, θ4 = θi + 2°, θ5 = θi - 2°, the control module calculates the theoretical speeds N4 and N5 corresponding to θ4 and θ5, and the noise monitoring module tests the corresponding Z4 and Z5 in these two rotation modes of the fan blade 2, and takes the angle correction direction corresponding to the minimum value among them as the secondary correction direction of the fan blade 2, and then, with 0.5° as the correction unit, corrects ten times in a step-by-step cumulative form in the secondary correction direction, and the noise monitoring module tests the corresponding Zi in these ten rotation modes of the fan blade 2. When Zi < Z0 and Zi is the minimum value, the corresponding θi and Ni are the inclination angle of the fan blade 2 and the rotation speed of the rotation axis after noise reduction; thus, while completing the noise reduction adjustment, the air volume is not affected, and its heat dissipation capacity is ensured; at the same time, through the above method, compared with the conventional adjustment process gradually decreasing from 30° to 15°, the adjustment in the present invention is faster and more efficient while ensuring accuracy. If in this process, there is no situation where Zi < Z0, the primary adjustment angle is modified to other angles and the process is carried out again until Zi < Z0 is found; if there is also no situation where Zi < Z0 in the correction process based on the two modified primary adjustment angles, the inclination angle of the fan blade 2 and the rotation speed of the rotation axis corresponding to the minimum Zi among all the detection results are taken as the current optimal fan startup parameters.

[0026] In this embodiment, due to the adjustable inclination angle of the fan blade 2, therefore, when Nmin < N < Nmax, there may also be a situation where Z > Z0. At this time, after the control module records the air volume as Q3, the control module respectively corrects θ to θ6 = θ0 - 2° and θ7 = θ0 + 2°. After each correction, the control module calculates the theoretical speeds N6 and N7 corresponding to θ6 and θ7 when Q is a fixed value through the above formula; at this time, Q = Q3, and the noise monitoring module tests the corresponding Z6 and Z7 in these two rotation modes of the fan blade 2, and takes the angle correction direction corresponding to the minimum value among them as the correction direction of the fan blade 2, and then, with 0.5° as the correction unit, corrects five times in a step-by-step cumulative form in the correction direction, and the noise monitoring module tests the corresponding Zi in these five rotation modes of the fan blade 2. When Zi < Z0 and Zi is the minimum value, the corresponding θi and Ni are the inclination angle of the fan blade 2 and the rotation speed of the rotation axis after noise reduction, thereby achieving noise reduction.

[0027] It is worth mentioning that the noise monitoring module distinguishes the comprehensive noise into pneumatic noise and mechanical noise through spectrum analysis, and records the pneumatic noise value as Zq and the mechanical noise value as Zj. Specifically, the noise monitoring module monitors the pneumatic noise through sensors arranged near the fan blade 2, and monitors the mechanical noise through sensors near the bearing and the motor. Therefore, when the control module identifies that Nmin < N < Nmax, the control module will calculate the value of a = Zq / Zj in real time. If a > 2, while correcting θ downward, N is corrected upward until 1.2 < a < 1.4; if 0.5 ≤ a < 0.8, while correcting θ upward, N is corrected downward until 1.2 < a < 1.4, thereby further improving the determination of the correction direction during the noise reduction process. Generally, 1.2 < a < 1.4 is the proportional range of normal pneumatic noise value and mechanical noise value. When a > 2, it means that the pneumatic noise accounts for a relatively large proportion and is relatively harsh. At this time, the inclination angle of the fan blade 2 is too large, and the inclination angle should be corrected downward; when 0.5 ≤ a < 0.8, it means that the mechanical noise accounts for a relatively large proportion and will also be perceived by the human body, and the rotational speed N should be corrected downward; if a < 0.5, the control module determines that the fan has a fault, such as bearing damage or jamming. At this time, the control module stops starting the fan and gives a warning for the user to adjust.

[0028] In addition, during the above correction process, when the angle adjustment of the fan blade 2 is completed, the lag time of the rotational speed adjustment of the rotating shaft is 50 - 100 ms, so that the noise transition is smooth without mutation, reducing the recognition accuracy of the noise monitoring module. An environmental noise detection module connected to the control module is also provided outside the main body frame, which is used to detect the environmental noise Zh while identifying the noise source, and record the minimum distance L1 and the relative angle θ8 from the noise source to the main body frame in real time. A radar detection module is also provided on the main body frame, which is used to detect the minimum distance L2 and the relative angle θ9 from the main body frame to the human body in real time. The control module calculates the distance L3 from the noise source to the human body in real time through L1, L2, θ8 and θ9. Let g = b (Z - 20log 10 L2) / (Zh - 20log 10 L3), where b is a constant input in advance and b > 2. When g ≤ 1, the control module determines that the noise generated by the fan is harmless noise, indicating that the environmental noise covers the noise generated by the fan. At this time, θ and N are not corrected; when g > 1, the control module determines that the noise generated by the fan is harmful noise, and at this time, θ and N are corrected accordingly to reduce Z; where, L3 = √(L1 2 + L2 2 - 2L1 L2 cosd), where d is determined by θ8 and θ9, and can be the addition or subtraction of the two, the specific situation of which is determined by the control module through actual simulation, and will not be elaborated here; while b is the sensitivity coefficient of noise discrimination ability, which can be input according to the user's actual sensitivity level.

[0029] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "upper," "lower," "left," "right," "front," "back," and similar expressions used in this document are for illustrative purposes only.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for adjusting the blade angle, applied to a cooling fan with adjustable blade angle, characterized in that: The cooling fan with adjustable blade angle includes a driving member provided on the main body frame and used for adjusting the rotation speed of the rotating shaft, a rotating body connected to the rotating shaft, a plurality of blades rotatably connected to the rotating body and connected to the angle adjustment mechanism, a noise monitoring module provided on the main body frame and used for detecting the noise source inside the main body frame, and a control module provided on the main body frame and connected to the noise monitoring module; the angle adjustment mechanism is provided on the rotating body, and both the driving member and the angle adjustment mechanism are connected to the control module; the control module adjusts the tilt angle θ of the blade and the rotation speed N of the rotating shaft through the driving member and the angle adjustment mechanism according to the received noise value Z. A noise threshold Z0 is preset on the control module. When the rotating shaft is in the high-speed operating condition and the received noise value is greater than the noise threshold, the control module upwardly corrects the tilt angle of the blade while downwardly correcting the rotation speed of the rotating shaft; when the rotating shaft is in the low-speed operating condition and the received noise value is greater than the noise threshold, the control module upwardly corrects the tilt angle of the blade while downwardly correcting the rotation speed of the rotating shaft. The control module has a preset standard tilt angle θ0, and the tilt angle of the fan blade is θi = θ0 ± 15°. When the control module operates at high speed on the rotating shaft and the received noise value is greater than the noise threshold, the control module corrects θ to θ1 = θ0 + 5°, θ2 = θ0 + 10°, and θ3 = θ0 + 15° respectively. After each correction, the control module uses the formula Ni = Q / (θi) A η k) Calculate the theoretical rotational speeds N1, N2, and N3 corresponding to θ1, θ2, and θ3 when Q is constant; the noise monitoring module tests the corresponding Z1, Z2, and Z3 under these three fan blade rotation modes, and takes the adjustment angle corresponding to the minimum value as the primary adjustment angle of the fan blade; Q is the air volume, k is the structural constant, A is the airflow cross-sectional area, and η is the aerodynamic efficiency.

2. The method for adjusting the fan blade angle according to claim 1, characterized in that, Taking the primary adjustment angle θi as a reference, θ is corrected upward and downward respectively, that is, θ4 = θi + 2°, θ5 = θi - 2°. The control module calculates the corresponding theoretical speeds N4 and N5 for θ4 and θ5. The noise monitoring module measures the corresponding Z4 and Z5 in these two blade rotation modes, and takes the angle correction direction corresponding to the minimum value as the secondary correction direction of the blade. Subsequently, with a correction unit of 0.5°, it is corrected ten times in a step-by-step cumulative form in the secondary correction direction. The noise monitoring module measures the corresponding Zi in these ten blade rotation modes. When Zi < Z0 and Zi is the minimum value, the corresponding θi and Ni are the tilt angle of the blade and the rotation speed of the rotating shaft after noise reduction.

3. The method for adjusting the fan blade angle according to claim 2, characterized in that, The control module has a preset standard tilt angle θ0, and the tilt angle of the fan blade is θi = θ0 ± 15°. When the control module operates at low speed on the rotating shaft and the received noise value is greater than the noise threshold, the control module corrects θ to θ1 = θ0 - 5°, θ2 = θ0 - 10°, and θ3 = θ0 - 15° respectively. After each correction, the control module uses the formula Ni = Q / (θi) A η k) Calculate the theoretical rotational speeds N1, N2, and N3 corresponding to θ1, θ2, and θ3 when Q is constant; the noise monitoring module tests the corresponding Z1, Z2, and Z3 under these three fan blade rotation modes, and takes the adjustment angle corresponding to the minimum value as the primary adjustment angle of the fan blade; Q is the air volume, k is the structural constant, A is the airflow cross-sectional area, and η is the aerodynamic efficiency.

4. The method for adjusting the fan blade angle according to claim 3, characterized in that, Taking the primary adjustment angle θi as a reference, θ is corrected upward and downward respectively, that is, θ4 = θi + 2°, θ5 = θi - 2°. The control module calculates the corresponding theoretical speeds N4 and N5 for θ4 and θ5. The noise monitoring module measures the corresponding Z4 and Z5 in these two blade rotation modes, and takes the angle correction direction corresponding to the minimum value as the secondary correction direction of the blade. Subsequently, with a correction unit of 0.5°, it is corrected ten times in a step-by-step cumulative form in the secondary correction direction. The noise monitoring module measures the corresponding Zi in these ten blade rotation modes. When Zi < Z0 and Zi is the minimum value, the corresponding θi and Ni are the tilt angle of the blade and the rotation speed of the rotating shaft after noise reduction.

5. The method for adjusting the blade angle according to claim 4, characterized in that, When the control module is between the low-speed condition and the high-speed condition of the rotating shaft and the received noise value is greater than the noise threshold; the control module respectively corrects θ to θ6 = θ0 - 2° and θ7 = θ0 + 2°. After each correction, the control module calculates the theoretical speeds N6 and N7 corresponding to θ6 and θ7 when Q is a fixed value; the noise monitoring module tests the corresponding Z6 and Z7 in these two fan rotation modes, and takes the angle correction direction corresponding to the minimum value as the correction direction of the fan. Subsequently, with 0.5° as the correction unit, it is corrected five times in a step-by-step cumulative form in the correction direction. The noise monitoring module tests the corresponding Zi in these five fan rotation modes. When Zi < Z0 and Zi is the minimum value, the corresponding θi and Ni are the inclination angle of the noise-reduced fan and the rotation speed of the rotating shaft.

6. The method for adjusting the fan blade angle according to claim 5, characterized in that, The noise monitoring module distinguishes the noise into aerodynamic noise and mechanical noise through spectral analysis, and records the aerodynamic noise value as Zq and the mechanical noise value as Zj; the control module will calculate the value of a = Zq / Zj in real time. If a > 2, then θ is corrected downward while N is corrected upward; if 0.5 ≤ a < 0.8, then θ is corrected upward while N is corrected downward; if a < 0.5, the control module determines that the fan has a fault and gives a warning.

7. The method for adjusting the blade angle according to claim 6, characterized in that, The main frame is also equipped with an environmental noise detection module connected to the control module. This module detects environmental noise Zh and identifies the noise source, recording in real time the minimum distance L1 and relative angle θ8 from the noise source to the main frame. The fan is also equipped with a radar detection module, which detects in real time the minimum distance L2 and relative angle θ9 from the main frame to the human body. The control module calculates the distance L3 from the noise source to the human body in real time using L1, L2, θ8, and θ9. Let g=b (Z-20log 10 L2) / (Zh-20log 10 L3), where b is a pre-input constant and b>2; when g≤1, the control module determines that the noise generated by the fan is harmless noise, and does not correct θ and N at this time; when g>1, the control module determines that the noise generated by the fan is harmful noise, and corrects θ and N accordingly to reduce Z.

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