Cooling fan with adjustable fan blade angle and adjusting method thereof

Abstract

The invention provides a cooling fan with an adjustable fan blade angle and an adjusting method of the cooling fan. The cooling fan comprises a driving part, a main body frame, a rotating main body, fan blades, 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 blades and the rotating speed of the rotating shaft according to the noise value Z, so that the noise in the main body frame is changed, high-frequency noise and low-frequency noise are restrained, and the cooling fan can meet the mute requirement when running under all working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation devices, and in particular to a heat dissipation fan with adjustable blade angles and an adjustment method thereof. Background Art

[0002] During fan operation, when cooling demand is high and the fan is running at high speeds (typically above 2500 rpm), the high-speed friction between the fan blades and the airflow generates high-frequency aerodynamic noise, typically concentrated in the frequency band above 2000 Hz. Furthermore, the operation of components such as the motor and bearings also generates mechanical noise, disrupting the user's work and living environment. Therefore, to reduce the noise generated at high fan speeds, without reducing cooling capacity (maintaining consistent airflow), the fan blade angle is typically set larger, thereby reducing the fan speed required to achieve the same cooling capacity and, in turn, reducing noise. However, when operating at low speeds, such as when cooling demand is low and stable cooling is required for a long period of time (typically below 1500 rpm), large-angle fan blades are prone to generating low-frequency eddy current noise (primarily distributed in the frequency band below 500 Hz) due to airflow separation. Therefore, traditional cooling fans with fixed blade angles have difficulty simultaneously suppressing both high- and low-frequency noise, making it difficult for cooling fans to meet silent requirements under all operating conditions. Summary of the Invention

[0003] The purpose of the present invention is to design a cooling fan with adjustable blade angle to solve the problems raised in the background technology. To achieve the above purpose, the present invention provides the following technical solution: comprising a driving member provided on a main frame and used to adjust the rotation speed of a rotating shaft, a rotating body connected to the rotating shaft, a plurality of blades rotatably connected to the rotating body and connected to an angle adjustment mechanism, a noise monitoring module provided on the main frame and used to detect noise sources inside the main frame, and a control module provided on the main frame and connected to the noise monitoring module; the angle adjustment mechanism is provided on the rotating body, and the driving member and the angle adjustment mechanism are both connected to the control module; the control module adjusts the inclination angle θ of the blades 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.

[0004] 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 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 operating 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 / (θixAxηxk); the noise monitoring module tests 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 structure constant, A is the air flow cross-sectional area, and η is the aerodynamic efficiency.

[0006] Further, θ is respectively corrected upward and downward based on the primary adjustment angle θi, 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 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 tests 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 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 is taken as: θi = θ0 ± 15°; when the control module is in a 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 x A x η x 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 structure constant, A is the air flow cross-sectional area, and η is the aerodynamic efficiency.

[0008] Further, θ is respectively corrected upward and downward 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 0.5° as the correction unit, it is corrected ten times in a step-by-step cumulative form in the direction of the secondary correction. 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 rotational speed of the rotating shaft.

[0009] Further, when the rotating shaft of the control module is between the low-speed operating condition and the high-speed operating condition 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 0.5° as the correction unit, it is corrected five times in a step-by-step cumulative form in the direction of the correction. 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 rotational speed of the rotating shaft.

[0010] Further, the noise monitoring module differentiates the noise into 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 will calculate the value of a = Zq / Zj in real time. If a > 2, then while correcting θ downward, N is corrected upward; if 0.5 ≤ a < 0.8, then while correcting θ upward, N is corrected downward; if a < 0.5, the control module determines that the fan has a fault and gives a warning.

[0011] Furthermore, after the fan blade angle adjustment is completed, the speed adjustment lag time of the rotating shaft is 50-100ms.

[0012] Furthermore, the main frame is provided with an environmental noise detection module connected to the control module, which is used to detect the environmental noise Zh and identify the noise source at the same time, and record the minimum distance L1 and relative angle θ8 from the noise source to the main frame in real time. The fan is also provided with a radar detection module, which is used to detect the minimum distance L2 and relative angle θ9 from the main 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 based on L1, L2, θ8 and θ9. Let g = bx(Z-20log 10 L2) / (Zh-20log 10 L3), where b is a pre-entered constant and b>2; when g≤1, the control module determines that the noise generated by the fan is harmless noise and does not modify θ and N; when g>1, the control module determines that the noise generated by the fan is harmful noise and makes corresponding modifications to θ and N 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 inclination angle of the fan blades and the speed of the rotating shaft through 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 silent requirements when operating under all working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 Schematic diagram of the internal structure of the rotating body.

[0016] Among them: 1. Rotating body; 2. Fan blades; 3. Driving motor; 4. First bevel gear; 5. Second bevel gear; 6. Reducer; 7. Main frame. DETAILED DESCRIPTION

[0017] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0018] Example: Please refer to Figure 1-2 , a cooling fan with adjustable fan blade angle, comprising a driving member provided on a main frame 7 and used to adjust the rotation speed of a rotating shaft, a rotating main body 1 connected to the rotating shaft, a plurality of fan blades 2 rotatably connected to the rotating main body 1 and connected to an angle adjustment mechanism, a noise monitoring module provided on the main frame 7 and used to detect a noise source inside the main frame 7, and a control module provided on the main frame 7 and connected to the noise monitoring module; the angle adjustment mechanism is provided on the rotating main body 1, and the driving member and the angle adjustment mechanism are both connected to the control module; the control module adjusts the inclination angle θ of the fan blade 2 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, wherein the driving member can adopt a servo motor; therefore, the control module in the present invention can adjust the inclination angle θ of the fan blade 2 and the rotation speed N of the rotating shaft according to the noise value Z inside the main frame 7, thereby changing the noise level inside the main frame 7, thereby suppressing the generation of high-frequency noise and low-frequency noise, so that the cooling fan can meet the silent requirements when operating under all working conditions.

[0019] Among them, the angle adjustment mechanism includes a drive motor 3 fixedly connected to the rotating body 1, a reducer 6 provided at the input end inside the rotating body 1 and connected to the drive motor 3, a first bevel gear 4 fixedly connected 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 to the inside of the rotating body 1, and a plurality of first bevel gears 4 are engaged with the second bevel gear 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, thereby realizing the adjustment of the inclination angle of the fan blade 2; in addition, the inclination 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 the angle affects the aerodynamic performance of the fan. When the inclination angle θ increases, the direction of the force of the fan blade 2 pushing the air changes, so that the air is accelerated and discharged in a direction farther away from the rotating plane. At the same speed, the air output can theoretically be increased; conversely, when the inclination angle θ decreases, the pushing effect of the fan blade 2 on the air is weakened, and the air output will be reduced.

[0020] 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 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 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, due to the low rotational speed, it is better to adopt the form of decreasing the tilt angle); 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 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 also 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 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; Usually, Nmin = 1500 rpm and Nmax = 2500 rpm; 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-condition operation.

[0021] In addition, the present application also discloses a specific correction process of the control module during the correction process, which greatly saves the correction time; that is, a standard inclination angle θ0 is preset on the control module, so the actual inclination angle θi of the fan blade 2 is θ0±15°; among them, 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, N>Nmax; at this time, the control module determines that the high-frequency noise generated by the fan blade 2 and the airflow reaches the point of interfering with the user's work and life, so the control module corrects θ to θ1=35°, θ2=40° and θ3=45° respectively. After each correction, the control module calculates the value of θ1, θ2=40° and θ3=45° when Q is a constant through the formula Ni=Q / (θixAxηxk). θ2 and θ3 correspond to the theoretical speeds N1, N2 and N3; the above formula is derived based on the quantitative relationship between speed and angle; at this time Q=Q1, since k is a structural constant, A is the airflow cross-sectional area, and η is the aerodynamic efficiency, all of which are determined by the structure of the fan blade 2. The user can determine it based on the existing fan structure, and there are no excessive restrictions here; and the noise monitoring module tests the corresponding Z1, Z2 and Z3 in the rotation modes of the fan blade 2 with an inclination angle of 35° and a rotation speed of the rotating shaft of N1; an inclination angle of 40° and a rotation speed of the rotating shaft of N2; an inclination angle of 45° and a rotation speed of the rotating shaft of N3, and takes the adjustment angle corresponding to the minimum value as the primary adjustment angle of the fan blade 2; thus, it can be preliminarily determined that the corresponding θ value when the actual noise reduction is completed will be near the primary adjustment angle; Subsequently, taking the primary adjustment angle θi as a reference, θ is corrected upward and downward respectively, i.e., 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 under 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 actually lies; 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 manner in the secondary correction direction. The noise monitoring module measures the corresponding Zi under 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 rotating shaft 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 that gradually increases 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 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 changed primary adjustment angles, the inclination angle of the fan blade 2 and the rotational speed of the rotating shaft corresponding to the minimum Zi among all the detection results are taken as the current optimal fan startup parameters.

[0022] 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 respectively corrects θ to θ1 = 25°, θ2 = 20° and θ3 = 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 / (θixAxηxk); at this time Q = Q2, 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, 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 rotational 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. 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 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, the noise reduction adjustment is completed without affecting its air output, ensuring its heat dissipation capacity; at the same time, through the above method, compared with the conventional adjustment process that gradually decreases from 30° to 15°, 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, then modify the primary adjustment angle to other angles and perform 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, then take 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 as the current optimal fan startup parameters.

[0023] In this embodiment, due to the adjustable tilt angle of the fan blade 2, when Nmin < N < Nmax, it is also possible that Z > Z0. At this time, after the control module records the air volume Q3, the control module respectively corrects θ to θ6 = θ0 - 2° and θ7 = θ0 + 2°. After each correction, the control module calculates the theoretical rotational speeds N6 and N7 corresponding to θ6 and θ7 when Q is a fixed value through the above formula; at this time Q = Q3, the noise monitoring module measures 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 as the correction direction of the fan blade 2. 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 measures 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 tilt angle of the noise-reduced fan blade 2 and the rotational speed of the rotation axis, thereby achieving noise reduction.

[0024] It is worth mentioning that the noise monitoring module distinguishes the comprehensive noise into aerodynamic noise and mechanical noise through spectrum analysis, and records the aerodynamic noise value as Zq and the mechanical noise value as Zj; specifically, the noise monitoring module monitors the aerodynamic 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, then θ is corrected downward while N is corrected upward until 1.2 < a < 1.4; if 0.5 ≤ a < 0.8, then θ is corrected upward while N is corrected downward until 1.2 < a < 1.4; thereby further improving the determination of the correction direction during the noise reduction process; in general, 1.2 < a < 1.4 is the proportional range of the normal aerodynamic noise value and mechanical noise value. When a > 2, it means that the aerodynamic noise accounts for a relatively large proportion and is relatively harsh. At this time, the tilt angle of the fan blade 2 is too large, and the tilt angle should be corrected downward; when 0.5 ≤ a < 0.8, it means that the mechanical noise accounts for a relatively large proportion and can 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.

[0025] In addition, during the above correction process, when the angle adjustment of the fan blade 2 is completed, the speed adjustment lag time of the rotating shaft is 50-100ms, so that the noise transition is smooth and without mutation, reducing the recognition accuracy of the noise monitoring module; and the outside of the main frame is also provided with an environmental noise detection module connected to the control module, which is used to detect the environmental noise Zh and identify the noise source at the same time, and record the minimum distance L1 and relative angle θ8 from the noise source to the main frame in real time. The main frame is also provided with a radar detection module for real-time detection of 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 through L1, L2, θ8 and θ9. Let g=bx(Z-20log 10 L2) / (Zh-20log 10 L3), where b is a pre-entered constant and b>2; when g≤1, the control module determines that the noise generated by the fan is harmless, indicating that the ambient noise covers the noise generated by the fan, and at this time, no correction is made to θ and N; when g>1, the control module determines that the noise generated by the fan is harmful, and at this time, the corresponding correction is made to θ and N to reduce Z; where L3=√(L1 2 +L2 2 -2L1xL2xcosd), where d is determined by θ8 and θ9, and can be the sum of the two, subtraction, etc. The specific situation is determined by the control module through actual simulation conditions, and will not be elaborated on here; and b is the sensitivity coefficient of noise resolution ability, and the corresponding value can be input according to the actual sensitivity of the user.

[0026] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "upper," "lower," "left," "right," "front," "rear," and similar expressions used herein are for illustrative purposes only.

[0027] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A cooling fan with adjustable blade angle, characterized in that: It includes a driving component provided on the main body frame and used to adjust the rotation speed of the rotating shaft, a rotating body connected to the rotating shaft, several fan 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 to detect the noise with the inside of the main body frame as the noise source, 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 component and the angle adjustment mechanism are connected to the control module; the control module adjusts the tilt angle θ of the fan blade and the rotation speed N of the rotating shaft through the driving component and the angle adjustment mechanism according to the received noise value Z.

2. The heat dissipation fan with adjustable blade angle according to claim 1, characterized in that: The angle adjustment mechanism includes a driving motor fixedly connected to the rotating body, a reducer provided inside the rotating body and with its input end connected to the driving motor, a first bevel gear fixedly connected to the end of the fan blade located inside the rotating body, and a second bevel gear connected to the output end of the reducer and rotatably connected inside the rotating body, and several first bevel gears are meshed with the second bevel gear.

3. A method for adjusting the angle of a fan blade, for adjusting the angle of a fan blade in the heat dissipation fan according to claim 1, characterized in that: 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, the control module upwardly corrects the tilt angle of the fan blade and downwardly corrects the rotation speed of the rotating shaft at the same time; when the rotating shaft is in a 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 fan blade and downwardly corrects the rotation speed of the rotating shaft at the same time.

4. The method for adjusting the blade angle according to claim 2, characterized in that: 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 rotating shaft is in a high-speed operating condition and the received noise value is greater than the noise threshold on the control module; 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 rotation speeds N1, N2 and N3 corresponding to θ1, θ2 and θ3 when Q is a fixed value through the formula Ni = Q / (θixAxηxk); the noise monitoring module tests 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 structure constant, A is the air flow cross-sectional area, and η is the pneumatic efficiency.

5. The method for adjusting the blade angle according to claim 4, characterized in that: 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 rotation speeds N4 and N5 corresponding to θ4 and θ5. The noise monitoring module tests 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 0.5° as the correction unit, it is corrected ten times in a step-by-step accumulation form in the secondary correction direction. The noise monitoring module tests 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 fan blade and the rotation speed of the rotating shaft after noise reduction.

6. The method for adjusting the blade angle according to claim 2, characterized in that: A standard tilt angle θ0 is preset on the control module, and the tilt angle of the fan blade is set as: θi = θ0 ± 15°; when the control module is in a 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 rotational speeds N1, N2 and N3 corresponding to θ1, θ2 and θ3 when Q is a constant value through the formula Ni = Q / (θi x A x η x k); the noise monitoring module measures 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 air flow cross-sectional area, and η is the pneumatic efficiency.

7. The method for adjusting the blade angle according to claim 6, characterized in that: 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 measures 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 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 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 noise-reduced fan blade and the rotational speed of the rotating shaft.

8. The method for adjusting the blade angle according to claim 7, characterized in that: When the rotating shaft of the control module is between the low-speed operating condition and the high-speed operating condition 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 rotational speeds N6 and N7 corresponding to θ6 and θ7 when Q is a constant value; the noise monitoring module measures the corresponding Z6 and Z7 in these two rotational 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 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 noise-reduced fan blade and the rotational speed of the rotating shaft.

9. The method for adjusting the blade angle according to claim 8, characterized in that: The noise monitoring module distinguishes the 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; 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 an alarm.

10. The method for adjusting the blade angle according to claim 9, characterized in that: The main frame is also provided with an environmental noise detection module connected to the control module, which is used to detect the environmental noise Zh and identify the noise source at the same time, and record the minimum distance L1 and relative angle θ8 from the noise source to the main frame in real time. The fan is also provided with a radar detection module, which is used to detect the minimum distance L2 and relative angle θ9 from the main 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 based on L1, L2, θ8 and θ9. Let g = bx(Z-20log 10 L2) / (Zh-20log 10 L3), where b is a pre-entered constant and b>2; when g≤1, the control module determines that the noise generated by the fan is harmless noise and does not modify θ and N; when g>1, the control module determines that the noise generated by the fan is harmful noise and makes corresponding modifications to θ and N to reduce Z.

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