Motor noise reduction device for handheld fan

Abstract

The application relates to the field of motor noise reduction technology, and discloses a motor noise reduction device for a handheld fan, the handheld fan comprising a fan blowing part and a handheld part, and a driving motor being arranged in the fan blowing part; the motor noise reduction device comprises: a noise collector arranged in the fan blowing part and used for collecting motor noise generated by the handheld fan during operation in real time; the motor noise comprises mechanical vibration noise, electromagnetic noise and aerodynamic noise of the driving motor; a noise processor arranged in the handheld part and electrically connected with the noise collector, used for generating a noise control instruction based on the motor noise when the signal strength of the motor noise is greater than a strength threshold; and a noise suppressor arranged in the fan blowing part and electrically connected with the noise processor, used for acquiring the noise control instruction and emitting a noise reduction signal according to the noise control instruction to perform destructive interference on the motor noise. The application reduces the motor operation noise level through active noise reduction and accurate processing of the fan motor noise.

Description

Technical Field

[0001] This invention relates to the field of motor noise reduction technology, and in particular to a motor noise reduction device for a handheld fan. Background Technology

[0002] In recent years, people have been pursuing a more convenient life. In order to meet the needs of outdoor activities or other life scenarios, a variety of portable fan products have appeared on the market, such as handheld fans and outdoor fans.

[0003] Currently, handheld fans inevitably generate noise during use. For example, the motor noise produced during operation, such as mechanical vibration noise and electromagnetic friction noise, is the main source of fan noise. Moreover, the higher the motor speed and the greater the airflow, the greater the noise, resulting in a poor user experience. Current methods for controlling motor noise are mostly passive, such as covering the inner wall of the fan with sound-absorbing cotton and optimizing heat dissipation channels. However, these methods have limited effectiveness in eliminating motor noise. Therefore, how to effectively eliminate the noise generated by the fan motor during operation is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] Therefore, it is necessary to provide a motor noise reduction device for handheld fans that can effectively reduce motor operating noise, addressing the aforementioned technical problems.

[0005] According to one aspect of the present disclosure, a motor noise reduction device for a handheld fan is provided, the handheld fan including an air delivery part and a handheld part, wherein a drive motor is disposed inside the air delivery part; the motor noise reduction device includes:

[0006] A noise collector is installed inside the air supply section to collect the motor noise generated by the handheld fan during operation in real time; the motor noise includes the mechanical vibration noise, electromagnetic noise and aerodynamic noise of the drive motor.

[0007] A noise processor, disposed on the handheld unit and electrically connected to the noise collector, is used to generate a noise control command based on the motor noise when the signal strength of the motor noise is greater than the strength threshold.

[0008] A noise suppressor is disposed inside the air supply section and electrically connected to the noise processor. It is used to acquire the noise control command and issue a noise reduction signal according to the noise control command to cancel the interference of the motor noise.

[0009] In one embodiment, the air supply section is further provided with an impeller assembly, the impeller assembly including a hub and a plurality of fan blades spaced apart on the outer surface of the hub;

[0010] The hub includes a conical cavity for enclosing and fixing the drive motor.

[0011] In one embodiment, the noise collector includes:

[0012] The first microphone is located on the inner wall of the conical cavity and is used to collect the electromagnetic noise generated by the drive motor during operation.

[0013] The second microphone is located on the outer surface of the hub and is used to collect the aerodynamic noise generated by the drive motor during operation.

[0014] The third microphone is mounted on the drive motor and is used to collect the mechanical vibration noise generated by the drive motor during operation.

[0015] In one embodiment, the noise processor includes:

[0016] The first processing submodule is used to perform frame segmentation, windowing and time-frequency transformation processing on the mechanical vibration noise, the electromagnetic noise and the aerodynamic noise respectively to obtain multiple corresponding frequency domain noise frames;

[0017] The first determining submodule is used to determine the noise suppression frame corresponding to each of the motor noises. The plurality of noise suppression frames correspond one-to-one with the plurality of frequency domain noise frames, and the corresponding noise suppression frames and frequency domain noise frames have opposite phases, the same amplitude and frequency.

[0018] The second determining submodule is used to determine the compensation gain corresponding to each frequency within the target frequency range based on the motor speed and vibration frequency of the drive motor, the air supply speed and the number of fan blades of the air supply section; the target frequency range is the frequency range in which the noise of each motor is located.

[0019] The first generation submodule is used to generate noise control commands for the mechanical vibration noise, the electromagnetic noise and the aerodynamic noise based on each of the noise suppression frames and the compensation gain corresponding to each frequency in the target frequency range.

[0020] In one embodiment, the noise suppressor includes a power amplifier and an audio player;

[0021] The power amplifier is used to acquire noise control commands for the mechanical vibration noise, the electromagnetic noise and the aerodynamic noise respectively, and amplify the noise reduction data carried by the various noise control commands to obtain the corresponding power amplification signal;

[0022] The audio player is used to emit noise reduction signals that are opposite in phase but have the same frequency and amplitude as the various motor noises, based on the power amplification signal.

[0023] In one embodiment, the audio player includes:

[0024] A first player is disposed on the inner wall of the conical cavity and corresponds to the first microphone, used to acquire a power amplified signal for the electromagnetic noise in order to play the first noise-reduced signal;

[0025] A second player is disposed on the outer surface of the hub and corresponds to the second microphone, for acquiring a power amplified signal for the aerodynamic noise in order to play the second noise-reduced signal;

[0026] A third player, mounted on the drive motor and corresponding to the third microphone, is used to acquire a power-amplified signal for the mechanical vibration noise in order to play a third noise-reduced signal.

[0027] In one embodiment, the noise processor further includes an amplitude comparator, the input of which is electrically connected to the noise collector and the output of which is electrically connected to the first processing submodule.

[0028] The amplitude comparator is used to acquire various types of motor noise and extract the corresponding noise amplitude sequence from the motor noise, so as to compare the noise amplitude sequence with a preset amplitude threshold to obtain the amplitude comparison result.

[0029] The first processing submodule is further configured to obtain the amplitude comparison result, and when the amplitude comparison result indicates that the noise amplitude sequence is greater than the amplitude threshold, generate a noise control command based on the motor noise; or, when the amplitude comparison result indicates that the noise amplitude sequence is less than or equal to the amplitude threshold, terminate the noise reduction program.

[0030] In one embodiment, the noise processor further includes a decibel comparator, the input of which is electrically connected to the noise collector and the output of which is electrically connected to the first processing submodule.

[0031] The decibel comparator is used to acquire the residual motor noise collected in real time by the noise collector after the noise suppressor emits the noise reduction signal, and extract the corresponding noise decibel value from the residual motor noise, so as to compare the noise decibel value with a preset decibel threshold to obtain the decibel comparison result.

[0032] The second processing submodule is used to obtain the decibel comparison result, and when the decibel comparison result is that the noise decibel value is greater than the decibel threshold, to reduce the speed of the drive motor, or when the decibel comparison result is that the noise decibel value is less than or equal to the decibel threshold, to end the noise reduction program.

[0033] In one embodiment, the noise processor further includes an error acquisition device disposed inside the air supply section and electrically connected to the first processing submodule. The error acquisition device is used to calculate the error between the motor noise and the motor noise to obtain error signal data, and to feed the error signal data back to the first processing submodule to calibrate the noise reduction signal.

[0034] In one embodiment, the drive motor is a three-phase high-speed micro motor with an operating speed exceeding a preset speed; wherein the preset speed is 12,000 rpm.

[0035] The aforementioned noise reduction device for handheld fans achieves precise noise reduction of various noises generated by the handheld fan drive motor through a linkage mechanism of noise acquisition, processing, and suppression, thereby improving the user's comfort and experience when using the handheld fan. On the other hand, unlike existing technologies, it combines noise control commands generated by a noise processor based on preset thresholds and algorithms with noise reduction signals emitted by a noise suppressor for destructive interference, thereby achieving active noise reduction and precise processing of the noise from the handheld fan drive motor to reduce the noise level generated during motor operation.

[0036] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0038] Figure 1 This is an application schematic diagram of a motor noise reduction device according to an exemplary embodiment;

[0039] Figure 2 This is a side cross-sectional view of a handheld fan according to an exemplary embodiment;

[0040] Figure 3 This is an exploded perspective view of a handheld fan according to an exemplary embodiment;

[0041] Figure 4 This is an exploded perspective view of another handheld fan according to an exemplary embodiment;

[0042] Figure 5 This is a side cross-sectional view of a drive motor according to an exemplary embodiment;

[0043] Figure 6 This is a schematic diagram of a noise processor module according to an exemplary embodiment;

[0044] Figure 7 This is a schematic diagram of a noise suppressor module according to an exemplary embodiment;

[0045] Figure 8 This is a schematic diagram of a module of an automated signal processing system according to an exemplary embodiment;

[0046] Figure 9 This is a logic diagram of an automated signal processing program according to an exemplary embodiment;

[0047] Figure 10 This is a logic diagram illustrating another automated signal processing procedure according to an exemplary embodiment;

[0048] Figure 11 This is a schematic diagram of a signal feedback control system according to an exemplary embodiment;

[0049] Figure 12 This is a block diagram illustrating a computer-readable storage medium for a handheld fan according to an exemplary embodiment. Detailed Implementation

[0050] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It is understood that the specific embodiments described herein are only for explaining this application and not for limiting it. Furthermore, it should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings, not all structures. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0051] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0052] The term "and / or" in the embodiments of this application refers to any and all possible combinations including one or more of the associated listed items. It should also be noted that, when used in this specification, "including / comprising" specifies the presence of the stated features, integers, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, elements, and / or components and / or groups thereof, and is intended to cover non-exclusive situations. For example, a product or device comprising a series of units is not limited to the listed units, but may optionally include units not listed, or may optionally include other units inherent to such products or devices.

[0053] The following text first describes the definitions of commonly used technical terms in this field:

[0054] 1. Active noise cancellation

[0055] Noise reduction is achieved by releasing a sound wave signal with the same or similar amplitude but opposite phase to the noise source, thereby reducing or eliminating the noise level of the noise source.

[0056] 2. Power amplifier

[0057] A power amplifier, often shortened to "amplifier," is an amplifier that can produce maximum power output to drive a load (such as a loudspeaker) under a given distortion rate. Power amplifiers play a pivotal role in the entire audio system, acting as a "coordinator" and, to a certain extent, determining whether the system can provide good sound quality.

[0058] 3. Loudspeakers

[0059] A loudspeaker, also known as a media player, is a very common electroacoustic transducer that can be found in any electronic or electrical device that produces sound.

[0060] To explain in detail the technical content, technical steps, objectives and effects of this application, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0061] With the development of technology and people's increasing demands for a comfortable living environment, noise reduction technology is being used more and more widely in electronic devices. Traditional fans generate significant noise during operation, which not only affects user comfort but may also interfere with sensitive locations (such as offices and hospitals). Therefore, developing a fan device that can effectively reduce operating noise is particularly important.

[0062] The purpose of this invention is to provide a motor noise reduction device for handheld fans, which can effectively reduce the noise of the drive motor while the portable fan generates cool air. This motor noise reduction device, through a linked mechanism of noise acquisition, processing, and suppression, achieves precise noise reduction of various noises generated by the handheld fan drive motor, improving the user's comfort and experience when using the handheld fan. Specifically:

[0063] This invention provides a motor noise reduction device 20 for a handheld fan 10. Please refer to [link / reference]. Figures 1 to 3 The handheld fan 10 includes an air delivery section 110 and a handheld section 120, with a drive motor 130 disposed inside the air delivery section 110. The motor noise reduction device 20 includes a noise collector 210, a noise processor 220, and a noise suppressor 230. The noise collector 210 is disposed inside the air delivery section 110 and is used to collect the motor noise generated by the handheld fan 10 during operation in real time. This motor noise includes mechanical vibration noise, electromagnetic noise, and aerodynamic noise from the drive motor 130. The noise processor 220 is disposed in the handheld section 120 and electrically connected to the noise collector 210, and is used to generate a noise control command based on the motor noise when the noise intensity of the noise signal exceeds an intensity threshold. The noise suppressor 230 is disposed inside the air delivery section 110 and electrically connected to the noise processor 220, and is used to acquire the noise control command and issue a noise reduction signal according to the noise control command to cancel out the motor noise.

[0064] In one embodiment, the air supply unit 110 includes an outer shell, which is a portable housing. Inside the housing, there is a cavity 101, and an air inlet 102 and an air outlet 103 are respectively provided at both ends of the housing and communicate with each other. A drive motor 130 is disposed in the cavity 101 and is used to rotate to generate wind pressure so as to draw air in from the air inlet 102, pass through the cavity 101, and blow it out from the air outlet 103.

[0065] For the casing, please refer to Figure 2 The casing is a user-friendly, portable design, meticulously crafted to be compact and easy to carry. Inside, a cavity 101 houses the drive motor 130, forming the basic frame of the handheld fan 10.

[0066] In some embodiments, such as Figure 2 As shown, the handheld fan 10 is mainly presented by its outer shell. In order to facilitate user carrying, the outer shell includes a handheld part 120 for the user to hold the hand shell 121, and an air supply part 110 for connecting the air inlet 102, the cavity 101 and the air outlet 103.

[0067] In some embodiments, such as Figure 2As shown, the fan housing 111 is a hollow cylindrical structure with an internal cavity 101. An air inlet 102 connecting to the outside is located at one end of the cavity 101, and an air outlet 103 connecting to the outside is located at the other end. An air inlet hood is located on one side of the air inlet 102, and an air outlet hood is located on one side of the air outlet 103. This allows air to be drawn into the cavity 101 through the air inlet hood from the air inlet 102 and then discharged through the air outlet hood from the air outlet 103, thus improving the overall airflow efficiency of the equipment. Simultaneously, the miniature design of the cavity 101 ensures flexibility during use.

[0068] In some embodiments, the air inlet 102 and the air outlet 103 are respectively located at the two ends of the air casing 111. The cross-sectional shape of the air inlet 102 and the air outlet 103 is circular, and the axes of the air inlet 102, the air outlet 103 and the cavity 101 are the same straight line.

[0069] In this embodiment, the cross-sections of the cavity 101, air inlet 102, and air outlet 103 are circular to ensure uniform suction and consistent external dimensions without differences in angle of use. Additionally, it maintains a consistent wall thickness for the fan housing 111, thereby guaranteeing the overall strength of the fan housing 111. In some embodiments, the cross-sectional shape of the cavity 101 can be elliptical or polygonal, and the cross-sections of the air inlet 102 and air outlet 103 can be oblong or rectangular polygonal. Furthermore, the positions of the air inlet 102 and air outlet 103 can be offset from the axis of the cavity 101. This application does not impose specific limitations on these aspects.

[0070] In this embodiment, the axis of the fan housing 111 is the central axis of the cylindrical shape. The airflow direction of the impeller assembly 140 for the handheld fan 10 during operation is parallel to this axis. In other embodiments, when the fan housing 111 is not cylindrical, its axis extends from the main structure, and the airflow direction is parallel to this axis. A buffer sleeve (not labeled, the same below) is also wrapped around the outside of the fan housing 111. Of course, in other embodiments, the buffer sleeve may not be provided.

[0071] In some embodiments, a battery module and control components are provided in the hand housing 121, and an impeller assembly 140 and a motor noise reduction device 20 are provided in the fan housing 111. The battery module (e.g., a battery) that powers various components and is located in the hand housing 121 of the handheld fan 10 can be logically connected to the motor noise reduction device 20 through a power management system, thereby enabling functions such as charging, discharging, and power consumption management through the power management system.

[0072] In some embodiments, the battery module supplies power to the drive motor 130, which drives the impeller assembly 140 to rotate to generate wind pressure, thereby drawing air in from the air inlet 102, passing through the cavity 101, and blowing it out from the air outlet 103.

[0073] In some embodiments, such as Figure 2 and Figure 3 As shown, the impeller assembly 140 is housed within the cavity 101 and is located on the side near the air inlet 102. The drive motor 130 includes a stator assembly 131 and a rotor assembly 132. The outer diameter of the drive motor 130 is smaller than the inner diameter of the cavity 101, and the drive motor 130 is mounted inside the cavity 101.

[0074] In some embodiments, such as Figure 3 As shown, the impeller assembly 140 includes a hub 141 and a plurality of blades 142 spaced around the hub. The outer diameter of the drive motor 130 is smaller than the maximum inner diameter of the hub 141, so a portion of the drive motor 130 can also be housed inside the hub 141. In this embodiment, the hub 141 increases radially from back to front, while the fan casing 111 remains radially constant from back to front. The maximum diameter of the hub 141 is not greater than the diameter of the fan casing 111, allowing the airflow generated by the rotation of the impeller assembly 140 to flow smoothly to the outside of the fan casing 111, reducing wind resistance and wind loss. In other embodiments, the difference between the maximum diameter of the hub 141 and the diameter of the fan casing 111 is less than 2 mm, which also achieves the effect of reducing wind resistance and wind loss.

[0075] In one embodiment, the rotor assembly 132 includes a shaft, a bearing, a magnetic ring, and a yoke. The bearing is housed within a bearing housing, and one end of the shaft is fixed to the bearing housing via the bearing. The magnetic ring is fixed radially inner to the yoke, and the yoke is fixedly connected to the shaft. The yoke and magnetic ring are located radially outer to the bearing housing. The stator assembly 131 is located between the bearing housing and the magnetic ring, and the other end of the shaft is fixedly connected to the impeller assembly 140. That is, the magnetic ring is located radially outer to the stator assembly 131, and the drive motor 130 is an external rotor motor. Furthermore, since the magnetic ring is fixed radially inner to the yoke, and the yoke is fixedly connected to the shaft, when the stator assembly 131 drives the magnetic ring to rotate, the magnetic ring simultaneously drives the yoke, and the yoke drives the shaft to rotate. Therefore, the magnetic ring or yoke does not need to be connected to the drive motor 130; the drive motor 130 can be fixedly connected to the other end of the shaft, and the shaft drives the drive motor 130 to rotate.

[0076] In some embodiments, the handheld fan 10 is applied to a high-speed motor with an operating speed exceeding a preset speed; that is, the drive motor 130 can be a three-phase high-speed micro motor with an operating speed exceeding a preset speed. The preset speed is 12,000 revolutions per minute.

[0077] Specifically, the handheld fan 10 can be used with a high-speed motor operating at speeds exceeding a preset speed (e.g., above 12,000 rpm). Such high-speed motors tend to generate high noise during actual operation, thus requiring active noise reduction control via the handheld fan 10. In some preferred embodiments, the high-speed motor can be a three-phase high-speed micro-motor. A high-speed three-phase motor can provide sufficient power and speed to ensure adequate airflow from the handheld fan 10. Furthermore, to ensure good overall vibration damping, a buffer can be installed on the inner wall of the housing 100. This buffer can absorb and reduce vibrations from the high-speed three-phase motor, allowing the portable active noise-canceling fan 10 to rotate continuously and stably at high speed.

[0078] In one embodiment, continue as follows Figure 3 As shown, the drive motor 130 is a three-phase high-speed micro motor, and the drive motor 130 also includes a drive plate 133. A fixing hole is provided inside the fan housing 111, and a fixing opening is provided on the drive plate 133. The fixing member passes through the fixing opening and is fixed to the fixing hole, thereby fixing the drive plate to the fan housing 111.

[0079] In one embodiment, when the handheld fan 10 is running, the drive motor 130 generates motor noise inside and outside the cavity 101, and this motor noise propagates in the form of an audio signal. Among the motor noise, the motor noise generated by the drive motor 130 during operation, such as mechanical vibration noise, electromagnetic noise, and aerodynamic noise, is the main source of noise for the fan.

[0080] Specifically, mechanical vibration noise is the sound generated by the vibration of internal mechanical components of a motor during relative motion due to friction, collision, imbalance, or structural resonance, which is transmitted into the air through the motor's connecting parts. Electromagnetic noise is the sound generated when the electromagnetic force (attraction or repulsion) between the stator and rotor of a motor fluctuates periodically due to changes in the magnetic field during operation, causing vibrations in the core, casing, and other structures, which are then transmitted through the air. Its core is the "periodic change of electromagnetic interaction." Aerodynamic noise is the sound generated when the internal or external air is disturbed during motor operation (such as airflow cutting, turbulence, or pressure changes). Its core is the "vibration of air particles." For example, when the motor rotor rotates, it drives the internal air (such as the air in the gap between the stator and rotor) to flow. If the gap is uneven or there are protruding structures (such as the ends of coils), it will cause air turbulence, generating high-frequency airflow noise.

[0081] In some embodiments, the noise collector 210 can collect motor noise signals in the cavity 101 in real time in response to the operation of the drive motor 130.

[0082] Specifically, the noise collector 210 is located inside the air supply section 110 and may include multiple microphone arrays and multiple vibration sensors. The microphone arrays are distributed at a preset angle around the drive motor 130 to collect motor noise signals propagating through the air; the vibration sensors are fixed to the motor bearing housing and stator housing with thermally conductive adhesive to monitor mechanical vibration data in real time. In some embodiments, the noise collector 210 collects the motor noise generated by the drive motor 130 during operation in real time, including mechanical vibration noise, electromagnetic noise, and aerodynamic noise, and sends it to the noise processor 220 for separate detailed analysis and processing.

[0083] In some embodiments, a noise processor 220 is disposed on a handheld unit 120. A pre-trained noise reduction model is pre-stored in the noise processor 220. The pre-trained noise reduction model can perform phase inversion processing on various motor noise signals to obtain inverted signal data, and generate corresponding noise control commands based on various inverted signal data.

[0084] The noise control command includes inverse signal data that is opposite in phase to the motor noise signal but has the same frequency and amplitude.

[0085] In some embodiments, the pre-trained noise reduction model can determine the spectral range and magnitude of the motor noise signal by analyzing the Hanning window spectrum of the motor noise signal, and calculate the corresponding inverted signal data. Then, the noise reduction model generates noise control commands based on the inverted signal data. When the inverted signal in the noise control command is superimposed on the motor noise signal, they will cancel each other out within the same frequency range, thereby achieving the effect of noise reduction or interference suppression.

[0086] In some embodiments, the noise reduction model can be integrated into the processing module of the handheld fan 10 to have signal processing capabilities. The aforementioned processing module can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), an embedded ARM processor, or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. The general-purpose processor can be a microprocessor; the computer chip can also be any conventional processor, etc., and is not specifically limited in this application.

[0087] In one embodiment, the noise suppressor 230 is integrated into the air supply section 110. It can receive noise control commands for mechanical vibration noise, electromagnetic noise and aerodynamic noise respectively, and issue corresponding noise reduction signals based on various noise control commands to actively control the noise of the handheld fan 10.

[0088] Within a preset error tolerance range, each noise reduction signal has the opposite phase and the same frequency and amplitude as its corresponding motor noise signal. This is used to perform destructive interference on mechanical vibration noise, electromagnetic noise, and aerodynamic noise, respectively, in order to achieve active noise control of the drive motor 130.

[0089] Specifically, sound is composed of a certain spectrum. The spectrum of the noise reduction signal is exactly the same as the noise signal to be eliminated, but the phase is exactly opposite. That is, a phase difference of 180° can completely cancel out the noise signal. In this way, after the noise reduction signal interferes with and interferes with the sound, the new sound wave generated can be so weak that it is inaudible to the human ear, thereby reducing the impact of motor noise on humans.

[0090] It should be understood that the noise acquisition unit 210 or the environmental noise measurement may be affected by external factors, such as background noise and temperature changes, which may lead to inaccurate signal acquisition. Different noise reduction algorithms have their applicable range and limitations. Some algorithms may not be able to effectively handle noise in all frequency ranges, resulting in inaccurate noise reduction frequency generation. Alternatively, the structure around the fan (such as walls, the ground and other objects) may affect the propagation characteristics of sound waves, producing reflection, diffraction or resonance, thereby changing the signal acquisition effect. Ultimately, this may result in the generated noise reduction signal not being completely out of phase (180°) with the motor noise signal, and / or the frequency and amplitude not being exactly the same. Therefore, a preset error allowable range can be set. As long as the generated noise reduction signal and the noise signal are within this error allowable range, they are considered to be out of phase and have the same frequency and amplitude.

[0091] In other embodiments, the three main motor noise signals described above will dynamically combine into a comprehensive noise signal and be transmitted to the user's hearing system during the user's use of the handheld fan 10 (e.g., while the user is walking, running, or remaining stationary while holding the handheld fan 10). In some embodiments, the noise collector 210 follows the user's usage scenario, collects the comprehensive noise signal dynamically composed of the aforementioned mechanical vibration noise, electromagnetic noise, and aerodynamic noise in real time, and sends it to the noise processor 220 for detailed analysis and processing.

[0092] Specifically, in practical applications, the handheld fan 10 can have multiple usage states, and the corresponding dynamic composite noise signal generated in each usage state is different. For example, when the user places it on a table as a desktop fan, the handheld fan 10 is in a stationary state, and the corresponding dynamic composite noise signal generated is static noise. Or, when the user holds it and moves it at irregular speeds and directions, the handheld fan 10 is in an irregular operating state, and the corresponding dynamic composite noise signal generated is dynamic noise.

[0093] In one possible implementation, the motor noise reduction device 20 provided in this application embodiment may further include a wireless communication component, wherein the noise processor 220, the noise collector 210, and the noise suppressor 230 are all electrically connected to the wireless communication component. Thus, the noise processor 220 can send noise control commands to multiple noise collectors 210 and multiple noise suppressors 230 via wireless communication, making the motor noise reduction device 20 more convenient to use. In a specific implementation, the wireless communication component includes at least one of a Bluetooth module, a WiFi module, and a 5G module.

[0094] To facilitate signal transmission, the wireless communication component employs wireless communication, which may include one or more of Bluetooth, WiFi, and 5G modules. A WiFi module is included in the wireless communication component to directly connect the noise processor 220, noise collector 210, and noise suppressor 230 to the internet, enabling communication between them. A Bluetooth module is a short-range wireless communication technology that replaces data cables. Bluetooth supports point-to-point and point-to-multipoint communication. The Bluetooth module wirelessly connects the noise processor 220, noise collector 210, and noise suppressor 230 into a micro-network, enabling fast and convenient communication between these modules. 5G is a next-generation broadband mobile communication technology characterized by high speed, low latency, and massive connectivity. Including a 5G module in the wireless communication component allows for interconnection of the noise processor 220, noise collector 210, and noise suppressor 230, enabling rapid communication between them. In specific implementations, the configuration can be tailored to the actual usage; this embodiment does not impose any limitations on this.

[0095] In a specific implementation scenario, the working principle of the handheld fan 10 can be as follows: When the handheld fan 10 is started, the main controller initializes all components; then the noise processor 220 reads at least one noise signal sent by the noise collector 210. If no noise signal is detected, the detection continues. If a noise signal is detected, the noise processor 220 analyzes the frequency, amplitude, and phase of each noise signal, and then generates a noise control command based on the analyzed noise frequency, amplitude, and phase. The noise control command is then sent to the corresponding matched noise suppressor 230 to instruct the noise suppressor 230 to emit a noise reduction signal with the same frequency and amplitude as the noise signal but opposite phase, in order to eliminate the noise signal.

[0096] The technical effects of the above solution are as follows: On the one hand, through the linkage mechanism of noise acquisition, processing and suppression, it can accurately reduce various noises generated by the handheld fan drive motor, thereby improving the user's comfort and experience when using the handheld fan; on the other hand, by combining a noise processor with noise control commands generated based on preset thresholds and algorithms, and then using a noise suppressor to emit noise reduction signals for destructive interference, it can achieve active noise reduction and accurate processing of the noise of the handheld fan drive motor, thereby reducing the noise level generated by the motor during operation.

[0097] Those skilled in the art will understand that the disclosed methods in the specific embodiments described above can be implemented in more specific ways. For example, the method by which the noise processor 220 generates noise control instructions based on the noise signal when the noise intensity is greater than an intensity threshold, etc., is merely a set of methods; in actual implementation...

[0098] There can be other ways of classifying them. For example, the noise generated by the handheld fan 10 during operation, including air intake noise, air exhaust noise, fan blade noise, and motor noise, can be combined or integrated into another system, or some features can be ignored or not executed.

[0099] In one embodiment, such as Figure 4 As shown, the impeller assembly 140 inside the air supply section 110 includes a hub 141 and a plurality of fan blades 142 spaced apart on the outer surface of the hub 141; wherein, the hub 141 includes a conical cavity 1411, which is used to cover and fix the drive motor 130.

[0100] In some embodiments, the hub 141 includes a guide surface that increases radially from rear to front, and a rotating shaft fixed at the center of the inner side of the hub 141. The stator assembly 131 and rotor assembly 132 of the drive motor 130 are both housed within the conical cavity 1411 of the hub 141. Further, the hub 141 includes an annular extension wall, within which the stator assembly 131 and rotor assembly 132 are housed. The stator assembly 131 is sleeved outside the sleeve of the circuit board 133, and includes coils. The rotor assembly 132 is radially disposed between the stator assembly 131 and the hub 14121. The rotating shaft at the center of the hub 141 is inserted into the sleeve, and the extension wall, stator assembly 131, and rotor assembly 132 extend forward into the clearance space.

[0101] In one embodiment, the noise collector 210 includes at least one microphone; wherein the at least one microphone is disposed at at least one target point within the cavity 101 to collect motor noise signals near each target point in real time.

[0102] In some embodiments, such as Figure 5 As shown, the noise collector 210 includes a first microphone 211, a second microphone 212, and a third microphone 213. The first microphone 211 is located on the inner wall (i.e., the annular extension wall) of the conical cavity 1411 and is used to collect electromagnetic noise generated by the drive motor 130 during operation. The second microphone 212 is located on the outer surface of the hub 141 and is used to collect aerodynamic noise generated by the drive motor 130 during operation. The third microphone 213 is located on the circuit board 133 of the drive motor 130 and is used to collect mechanical vibration noise generated by the drive motor 130 during operation.

[0103] Specifically, the first pickup 211 senses the electromagnetic radiation of the motor windings and converts the magnetic field change into a voltage signal; the second pickup 212 captures the sound wave pressure change generated by the interaction between the blade 142 and the air; and the third pickup 213 converts the mechanical vibration of the circuit board 133 into an electrical signal. These three signals are preprocessed and then synchronously transmitted to the noise processor 220.

[0104] In an exemplary embodiment, the noise collector 210 is located inside the air supply section 110 and adopts a distributed multi-source acquisition architecture. Specifically, it includes: a first microphone 211, which is a miniature electromagnetic induction sensor (such as the T942-10 type), located on the inner wall (annular extension wall) of the conical cavity 1411, and connected to the noise processor 220 via a magnetically shielded cable. Its sensing end is close to the stator winding of the drive motor 130, and is used to collect electromagnetic noise in the 100-5000Hz frequency band, especially the pulse electromagnetic radiation generated by the motor commutation. The second microphone 212 is a MEMS microphone array (sensitivity -42dBFS, frequency response 20-20000Hz), located on the outer surface of the hub 141 near the root of the blade 142, and fixed by a silicone vibration damping seat. Its sound pickup direction is towards the fan blade rotation surface, and it is used to collect turbulence noise and eddy current noise generated by air flowing through the fan blade. The third pickup 213 is a piezoelectric vibration sensor (range ±5g, resonant frequency 10kHz), which is attached to the circuit board 133 of the drive motor 130 (i.e., the power drive module area) with thermally conductive adhesive. It is used to collect mechanical vibration noise generated by motor bearing friction and rotor imbalance, with a sampling frequency of up to 44.1kHz.

[0105] In some embodiments, since the noise of the impeller assembly 140 is mainly generated when the impeller assembly 140 rotates, in one possible implementation, the second pickup 212 is disposed on the outer surface of the hub 141 of the impeller assembly 140 and is configured to collect the aerodynamic noise generated during the operation of the hub.

[0106] In this way, the second pickup 212 can transmit the aerodynamic noise to the noise processor 220 to extract the amplitude, frequency and phase characteristics of the noise signal, and generate a noise reduction signal to cancel the noise signal through the noise suppressor 230, thereby partially or completely eliminating the aerodynamic noise generated by the blades of the impeller assembly 140 when rotating.

[0107] Furthermore, in addition to the hub 141 and blades 142 of the impeller assembly 140 generating significant noise when rotating with the drive motor 130, the rotor assembly 132 of the drive motor 130 also generates noise signals when cutting magnetic lines of force, and the friction between the rotor assembly 132 and the stator assembly 131. In some embodiments, the noise collector 210 further includes a first pickup 211 and a third pickup 213. The first pickup 211 is disposed on the inner wall of the conical cavity 1411, and the third pickup 213 is disposed on the circuit board 133, and is configured to collect the electromagnetic noise and mechanical vibration noise of the drive motor 130, respectively.

[0108] Thus, the first pickup 211 can transmit the electromagnetic noise to the noise processor 220, and the second pickup 213 can transmit the mechanical vibration noise to the noise processor 220, so as to extract the amplitude, frequency and phase characteristics of the noise signal respectively, and generate a noise reduction signal to cancel the noise signal using the noise suppressor 230 based on these characteristics, thereby partially or completely eliminating the electromagnetic noise generated by the drive motor 130 during operation.

[0109] In other embodiments, although the related technology reduces the noise generated when air flows in the cavity 101 by improving the structure of the air casing, some noise is still inevitably generated when air flows in the cavity 101. Therefore, in some embodiments, the noise collector 210 also includes a fourth microphone, which is respectively disposed on the inner wall near the air inlet 102, the air outlet 103 and the center of the air duct 104 in the cavity 101, and is configured to collect the noise signals of the air inlet 102, the air outlet 103 and the center of the air duct 104.

[0110] Thus, the fourth microphone can collect the noise signal generated when air flows in the cavity 101 and transmit the noise signal to the noise processor 220 to extract the amplitude, frequency and phase characteristics of the noise signal. Based on these characteristics, the noise suppressor 230 generates a noise reduction signal to cancel the noise signal, thereby eliminating the noise signal generated at the air inlet 102, air outlet 103 and air duct center 104 in the cavity 101 when the impeller assembly 140 is running.

[0111] In one embodiment, such as Figure 6 As shown, the noise processor 220 includes a first processing submodule 221, a first determining submodule 222, a second determining submodule 223, and a first generating submodule 224. The first processing submodule 221 performs framing, windowing, and time-frequency transformation processing on mechanical vibration noise, electromagnetic noise, and aerodynamic noise respectively to obtain multiple corresponding frequency domain noise frames. The first determining submodule 222 determines the noise suppression frame corresponding to each motor noise, with multiple noise suppression frames corresponding one-to-one with multiple frequency domain noise frames, and the corresponding noise suppression frames and frequency domain noise frames having opposite phases but the same amplitude and frequency. The second determining submodule 223 determines the compensation gain corresponding to each frequency within a target frequency range based on the motor speed and vibration frequency of the drive motor 130, and the airflow speed and number of fan blades of the air supply unit 110. This target frequency range is the frequency range where each motor noise is located. The first generating submodule 224 generates noise control commands for mechanical vibration noise, electromagnetic noise, and aerodynamic noise based on each noise suppression frame and the compensation gain corresponding to each frequency within the target frequency range.

[0112] In one exemplary embodiment, a noise processor 220 is disposed on the handheld unit 110, employs a dual-core DSP chip (such as ADI ADSP-BF707), integrates four functional sub-modules, and realizes real-time signal processing (total delay ≤10ms) through a hardware acceleration unit.

[0113] In some embodiments, the first processing submodule 221 performs signal preprocessing on the mechanical vibration noise collected by the third pickup 213, the electromagnetic noise collected by the first pickup 211, and the aerodynamic noise collected by the second pickup 212, respectively. This includes: performing frame segmentation with a frame length of 20ms and an overlap rate of 50% to balance time resolution and frequency resolution; applying a Hanning window to mechanical vibration noise (to reduce spectral leakage), a rectangular window to electromagnetic noise (to preserve impulse characteristics), and a Blackman window to aerodynamic noise (to improve high-frequency resolution); and converting the time-domain signal to the frequency domain through a fast Fourier transform (FFT, 1024 points) to obtain multiple frequency-domain noise frames corresponding to the noise (frequency resolution ≤ 20Hz).

[0114] In some embodiments, the first determining submodule 223 generates a corresponding noise suppression frame based on the phase, amplitude, and frequency parameters of the frequency domain noise frame; then, it performs phase reversal (Δφ = π) on each frequency domain noise frame to ensure destructive interference with the original noise; then, it uses automatic gain control (AGC) to make the amplitude of the noise suppression frame consistent with that of the frequency domain noise frame (error ≤ 3%); finally, it uses phase-locked loop (PLL) technology to keep the frequency of the noise suppression frame synchronized with that of the frequency domain noise frame (drift ≤ 0.1Hz) to ultimately form a noise suppression frame sequence that corresponds one-to-one with the frequency domain noise frame.

[0115] In some embodiments, the second determining submodule 223 constructs a dynamic compensation model 2231, which calculates the compensation gain within the target frequency range based on multi-parameter fusion. Specifically, this includes: inputting the real-time rotational speed of the drive motor (collected by a Hall sensor, range 2000-6000 rpm), vibration frequency (extracted from the signal of the third microphone), airflow speed of the air supply section (converted from the impeller speed, range 3-8 m / s), number of fan blades (preset parameter, such as 6 blades), and the target frequency range, such as mechanical vibration noise (500-3000 Hz), electromagnetic noise (1000-5000 Hz), and aerodynamic noise (800-8000 Hz); then using a piecewise function for dynamic adjustment, for example: when the motor speed is >4000 rpm, the aerodynamic noise compensation gain is increased by 1.2 times; when the vibration frequency is in the resonant frequency band (1800-2200 Hz), the mechanical vibration noise compensation gain is increased to 1.5 times; finally, the electromagnetic noise compensation gain is positively correlated with the current intensity.

[0116] In some embodiments, the first generation submodule 224 integrates the noise suppression frame and the compensation gain to generate dedicated control instructions for three types of noise. Specifically, the noise suppression frame is multiplied by the compensation gain and converted into a PWM control signal (frequency 1-10kHz). Then, the processed suppression frame is subjected to D / A conversion to generate an analog voltage signal (0-3.3V). Finally, an audio drive signal (power ≤0.5W) is generated through a digital-to-analog converter to transmit all instructions to the noise suppressor 230 via the SPI bus, ensuring real-time performance.

[0117] In other embodiments, the first processing submodule 221 may also use an analog-to-digital converter to perform analog-to-digital conversion processing on the motor noise signals of each frame to obtain the corresponding pulse code signals; then, the pulse code signals of each frame are input into the first determining submodule 222 to perform phase inversion processing to obtain the noise suppression frames corresponding to each motor noise.

[0118] In some embodiments, the pulse-coded signal is an audio pulse-code modulation (PCM) signal.

[0119] Specifically, the analog-to-digital converter (ADC) is an electronic device or circuit that converts analog signals into digital signals. This process, called analog-to-digital conversion, aims to enable analog signals to be processed by a digital computer or the first deterministic submodule 222.

[0120] In some embodiments, the basic steps of analog-to-digital conversion are as follows:

[0121] ① Input amplified signal: Typically, this amplified signal is an amplified analog signal, such as the output from an audio amplifier, temperature sensor, or other sensor.

[0122] ② Sampling: The analog-to-digital converter detects the input analog signal at a certain sampling frequency. This frequency needs to be higher than the Nyquist frequency of the signal (generally twice the signal frequency) to ensure signal integrity.

[0123] ③ Quantization: Converting the sampled analog signal values ​​into discrete digital values. Quantization errors may occur at this stage.

[0124] ④ Encoding: The quantized value is encoded into a digital signal, usually in binary encoding form (such as pulse code modulation, PCM), and output as a digital signal.

[0125] In some embodiments, Pulse Code Modulation (PCM) is a digital signal representation method widely used in the digital representation of audio, video, and other analog signals. Its characteristics include: signal discretization: PCM converts continuous analog signals into a series of discrete digital values ​​through sampling and quantization; energy efficiency and bandwidth efficiency: digital signals encoded with PCM are less susceptible to noise interference during transmission, and compression techniques can reduce transmission bandwidth.

[0126] The first determining submodule 222 is used to perform phase inversion processing on the pulse code signal to obtain inverted signal data, that is, the noise suppression frame corresponding to each motor noise.

[0127] In one embodiment, the inverted signal data includes pulse-coded data that is out of phase with the pulse-coded signal but has the same frequency and amplitude.

[0128] In some embodiments, the first determining submodule 222 can determine the spectral range and magnitude of the pulse-coded signal by analyzing the Hanning window spectrum of the pulse-coded signal, and calculate the corresponding inverted signal data.

[0129] Specifically, when analyzing the spectrum of pulse-coded signals, using the Hanning window is an effective method to reduce spectral leakage and improve the accuracy of spectrum estimation. The steps are as follows:

[0130] 1. Signal preprocessing

[0131] Before processing the pulse-coded signal, the first determining submodule 222 applies a Hanning window function to process the original signal. This can be achieved using the following formula:

[0132]

[0133] Where N is the length of the signal.

[0134] 2. Calculate the spectrum

[0135] The first determining submodule 222 performs a Fast Fourier Transform (FFT) on the signal processed by the window function to calculate the spectrum. This Fast Fourier Transform can be implemented using the following formula:

[0136]

[0137] Where X[k] is the spectrum and x[n] is the time-domain signal after window function processing.

[0138] 3. Extract frequency and amplitude

[0139] The first determining submodule 222 performs spectral analysis on the spectrum based on the FFT results to extract the signal's frequency and amplitude. The steps include:

[0140] First, calculate the amplitude spectrum: Then find the main frequency components and their corresponding amplitudes.

[0141] 4. Calculate the inverted signal data

[0142] The first determining submodule 222 calculates the inverted signal data: To obtain an inverted signal with opposite phase, first determine the amplitude A and phase φ of a certain frequency f. This inverted signal can be represented as:

[0143] A 反 =A,φ 反 =φ+π;

[0144] This means that if the original signal is represented by the complex number X = Ae at frequency f: jφ ;

[0145] Therefore, the inverted signal data can be represented as: X 反 =Ae j(φ+π) =-Ae jφ .

[0146] In one embodiment, the noise suppressor 230 includes at least one audio player 231 and a power amplifier 232 disposed at each target point;

[0147] Among them, the power amplifier 232 is used to acquire noise control commands for mechanical vibration noise, electromagnetic noise and aerodynamic noise respectively, and amplify the noise reduction data carried by various noise control commands to obtain the corresponding power amplification signal.

[0148] Specifically, the power amplifier 232 includes a power amplifier circuit, which includes a signal input terminal and a signal output terminal. The signal input terminal of the power amplifier circuit is electrically connected to the first generation submodule 224. The first generation submodule 224 includes multiple signal output ports for outputting generated noise control commands. The signal input terminal of the power amplifier circuit is electrically connected to the signal output ports of the first generation submodule 224. The signal output terminal of the power amplifier circuit is electrically connected to the audio player 231. The power amplifier circuit is used to amplify the noise reduction data generated by the first generation submodule 224.

[0149] The audio player 231 is used to emit noise reduction signals that are opposite in phase to various motor noises but have the same frequency and amplitude, based on the power amplification signal.

[0150] Specifically, after the first generation submodule 224 generates the noise reduction data, it needs to be played out through the audio player 231 so that the noise reduction signal interferes with or interferes with the noise signal, thereby canceling out part or all of the noise signal.

[0151] In some embodiments, the noise suppressor 230 performs digital-to-analog conversion and signal amplification on the noise-reduced signal data input from the first generation submodule 224, and then outputs it to the audio player 231. This noise-reduced signal data is mainly used to suppress noise signals from the original environment; this process is called active noise cancellation, and the principle of active noise cancellation is as follows: Figure 7 As shown.

[0152] Therefore, the noise suppressor 230 may include multiple audio players 231, each audio player 231 and the microphone having a one-to-one correspondence in position, so that the noise reduction signal played by different audio players 231 can eliminate the corresponding noise signal.

[0153] In one embodiment, please continue as follows Figure 5 As shown, the audio player 231 includes: a first player 2311 disposed on the inner wall of the conical cavity 1411 and corresponding to the first microphone 211, used to acquire a power amplified signal for electromagnetic noise to play a first noise-reduced signal; a second player 2312 disposed on the outer surface of the hub 141 and corresponding to the second microphone 212, used to acquire a power amplified signal for aerodynamic noise to play a second noise-reduced signal; and a third player 2313 disposed on the circuit board 133 of the drive motor 130 and corresponding to the third microphone 213, used to acquire a power amplified signal for mechanical vibration noise to play a third noise-reduced signal.

[0154] Specifically, the noise suppressor 230 is located inside the air supply section 110, and its core component is the audio player 231, which adopts a distributed layout to form a one-to-one correspondence with the noise collector 210. Specifically, the first player 2311 receives electromagnetic noise control commands and generates a reverse electromagnetic field through an electromagnetic speaker, creating destructive interference with the electromagnetic noise of the drive motor 130 in the stator winding region; the second player 2312 receives aerodynamic noise control commands and emits anti-phase sound waves through a MEMS speaker, creating acoustic interference in the airflow generated by the fan blade rotation to cancel turbulence noise; the third player 2313 receives mechanical vibration noise control commands and generates anti-phase vibration through a piezoelectric vibrator, which is transmitted to the motor housing via the circuit board 133 to cancel mechanical vibration transmission. The spatial matching degree between these three types of noise reduction signals and their corresponding noise sources is over 90%, ensuring maximum interference effect.

[0155] Since the noise of the impeller assembly 140 is mainly generated when the impeller assembly 140 rotates, in one possible implementation, the second player 2312 is disposed on the hub 141 of the impeller assembly 140 and is configured to play an inverse noise-reducing signal to the rotating blades 142.

[0156] In this way, the second player 2312 can play an inverse noise reduction signal to the operating blades according to the noise control command issued by the first generation submodule 224, so as to cancel the noise signal generated in the target area, thereby partially or completely eliminating the noise generated by the blades 142 of the impeller assembly 140 when rotating.

[0157] Furthermore, in addition to the significant noise generated by the hub 141 and blades 142 during rotation, noise signals are also generated by the rotor assembly 132 of the drive motor 130 cutting magnetic lines of force and by friction between the rotor assembly 132 and the stator assembly 131. In some embodiments, a first player 2311 is disposed on the inner wall of the conical cavity 1411, and a third player 2313 is disposed on the circuit board 133 and configured to play an inverse noise-reducing signal to the operating drive motor 130.

[0158] Thus, the first player 2311 and the third player 2313 can play an inverse noise reduction signal to the running drive motor 130 according to the noise control command issued by the first generation submodule 224, so as to cancel the noise signal generated in the target area, thereby partially or completely eliminating the noise generated by the drive motor 130 of the impeller assembly 140 during operation.

[0159] In other embodiments, although the related technology reduces the noise generated when air flows through the cavity 101 by improving the structure of the fan shell, some noise is still inevitably generated when air flows through the cavity 101. Therefore, in some embodiments, the plurality of audio players 231 also include a fourth speaker, which is respectively disposed on the inner wall near the air inlet 102, the air outlet 103 and the center of the air duct 104 in the cavity 101, and is configured to play an inverse noise-reducing signal to the target area near the air inlet 102, the air outlet 103 and the center of the air duct 104.

[0160] Thus, the fourth speaker can play inverse noise reduction signals to the target areas near the air inlet 102, air outlet 103 and air duct center 104 respectively, according to the noise control command issued by the first generation submodule 224, so as to cancel the noise signal generated in the target area, thereby eliminating the noise generated in the air inlet 102, air outlet 103 and air duct center 104 in the cavity 101 when the impeller assembly 140 is running.

[0161] In other embodiments, the audio player 231 for each target area may also include a plurality of noise-canceling speakers, and at least two of the noise-canceling speakers are oriented differently.

[0162] In other words, when collecting noise signals, multiple noise collectors 210 will collect noise signals from different parts of the impeller assembly 140. In order to specifically cancel different noise signals, different cancellation sound wave signals need to be generated and played according to the propagation direction of different noise signals. Therefore, during playback, the propagation direction of the noise reduction signal for different noise signals will also be different. Thus, the sound playback direction of multiple noise reduction speakers is different to eliminate noise signals propagating from various directions.

[0163] In some implementations, the number of noise-canceling speakers can be an even number, with multiple noise-canceling speakers arranged in a circle, and the orientations of two opposing noise-canceling speakers facing away from each other.

[0164] For example, the number of noise-canceling speakers can be four or six. When there are four noise-canceling speakers, adjacent speakers are arranged at a 90-degree angle, and all speakers face outwards. When there are six noise-canceling speakers, adjacent speakers are arranged at a 60-degree angle, and opposite speakers face back to back. In this way, multiple noise-canceling speakers can play noise-canceling wave signals in all directions to better eliminate noise.

[0165] In one exemplary embodiment, the first player 2311 is a miniature electromagnetic loudspeaker (6mm in diameter, 2mm thick), disposed on the inner wall of the conical cavity 1411 and symmetrically distributed 180° with the first pickup 211 (electromagnetic noise acquisition end). Its diaphragm faces the stator winding of the drive motor 130, and it incorporates neodymium iron boron magnets to enhance the magnetic field response, with a frequency response range of 1000-5000Hz (covering the main frequency band of electromagnetic noise). It is connected to a power amplifier circuit via a 10mm long shielded cable to receive a power amplification signal for electromagnetic noise and play a first noise reduction signal that is out of phase with the electromagnetic noise, so as to cancel electromagnetic radiation noise through electromagnetic field interference.

[0166] In one exemplary embodiment, the second player 2312 employs an ultra-thin MEMS speaker (8mm × 8mm in size, 1.2mm in thickness), positioned on the outer surface of the hub 141 near the center of the blade 142, maintaining a 30° angle with the second microphone 212 (aerodynamic noise acquisition end), with both pickup and playback directions pointing towards the plane of rotation of the blade 142. Its frequency response range is 800-8000Hz, and its sound pressure level is 90dB / kHz. It is fixed with a silicone vibration damping bracket to avoid interference from its own vibration. After receiving a power-amplified signal targeting aerodynamic noise, it plays a second noise-reducing signal (i.e., an anti-phase sound wave), forming an acoustic interference zone around the fan blades to cancel out turbulence and eddy current noise.

[0167] In one exemplary embodiment, the third player 2113 is a piezoelectric ceramic vibrator (5mm in diameter, 0.8mm thick), attached to the grounded copper foil area of ​​the circuit board 133, adjacent to the third microphone 213 (mechanical vibration noise acquisition end) (spacing ≤2mm). Its resonant frequency is 100-3000Hz, with a maximum amplitude of 5μm, and it is fixed with thermally conductive double-sided adhesive to combine vibration transmission and heat dissipation. After receiving a power-amplified signal targeting mechanical vibration noise, it generates a third noise-reducing signal (i.e., a mechanical vibration wave) with an opposite phase to the motor vibration, which is transmitted through the circuit board 133 to the motor housing, canceling out vibrations caused by bearing friction and rotor imbalance.

[0168] In one embodiment, please refer to Figure 8 and Figure 9 The noise processor 220 also includes an amplitude comparator 225, the input of which is electrically connected to the noise collector 210 and the output of which is electrically connected to the first processing submodule 221.

[0169] The amplitude comparator 225 is used to acquire various motor noises and extract the corresponding noise amplitude sequence from the various motor noises, so as to compare the noise amplitude sequence with the preset amplitude threshold to obtain the amplitude comparison result.

[0170] In some embodiments, the first processing submodule 221 is further configured to obtain amplitude comparison results, and generate noise control instructions based on motor noise when the amplitude comparison result is that the noise amplitude sequence is greater than the amplitude threshold; or, terminate the noise reduction program when the amplitude comparison result is that the noise amplitude sequence is less than or equal to the amplitude threshold.

[0171] Specifically, the amplitude comparator 225, the analog-to-digital converter, and the first processing submodule 221 described above can form an automated signal processing system 240 based on amplitude comparison and active noise reduction. The following section will provide a detailed analysis of each part of this automated signal processing system 240 and its workflow.

[0172] 1. Introduction to System Components

[0173] Analog-to-digital converter (ADC): Used to convert analog signals (i.e., combined noise signals) into digital signals for subsequent processing modules.

[0174] Amplitude Comparator 225: Used to acquire the pulse-coded signal from the analog-to-digital converter. It extracts the amplitude sequence of noise and compares it to a preset amplitude threshold. This process allows the system to determine whether noise reduction measures are needed given the current noise level.

[0175] The first processing submodule 221 is used to receive the amplitude comparison result output by the amplitude comparator and execute the corresponding logic operation. Based on the comparison result, it determines whether to perform phase inversion processing on the motor noise signal to generate inverted signal data for active noise reduction.

[0176] 2. System Workflow

[0177] Signal input and conversion: The motor noise signal is first converted into a digital pulse code signal by an analog-to-digital converter, which is then used by the amplitude comparator 225.

[0178] Amplitude extraction and comparison: Amplitude comparator 225 extracts the amplitude sequence of noise from the pulse-coded signal. The extracted amplitude sequence is then compared with a preset amplitude threshold to generate an amplitude comparison result. If the amplitude sequence is greater than the threshold, noise reduction processing is required; if the amplitude sequence is less than or equal to the threshold, the noise reduction process ends.

[0179] Phase Inversion Signal Generation: If the amplitude comparison result indicates that the noise amplitude sequence is greater than the amplitude threshold, the first processing submodule 221 will initiate phase inversion processing, including processing the pulse-coded signal to generate phase inversion signal data. This phase inversion signal data is used for active noise reduction to cancel the original noise signal.

[0180] Program termination: If the amplitude comparison result shows that the noise amplitude sequence is less than or equal to the set amplitude threshold, the noise reduction program will be terminated and signal processing will be stopped.

[0181] The processing logic of the automated signal processing system 240 is such that, as long as the motor noise does not affect the user experience or use, the automated signal processing system 240 does not need to process the motor noise. This is beneficial for the energy saving of the handheld fan 10, especially when the current battery level of the handheld fan 10 is low, it can further extend the standby time. Therefore, the automated signal processing system 240 can determine whether to reduce the motor noise based on the amplitude value of the current motor noise signal. If the current fan noise is insufficient to affect the user experience or use, active noise reduction will not be performed; otherwise, active noise reduction will be performed.

[0182] 3. System Functions

[0183] Automated control: The automated signal processing system 240 effectively generates an automated response program that can adjust noise reduction strategies according to real-time changes in ambient noise.

[0184] Precise noise reduction: Through amplitude comparison and phase inversion technology, active noise reduction improves the working efficiency of the handheld fan 10 under different noise conditions.

[0185] 4. System Settings

[0186] Threshold setting: Setting an appropriate amplitude threshold for the automated signal processing system 240 is crucial. If the threshold is set too high, it may lead to unnecessary noise reduction; if it is set too low, it may lead to frequent noise reduction and unnecessary processing delays.

[0187] Latency impact: The signal processing delay of the automated signal processing system 240 may affect the noise reduction effect. Therefore, the automated signal processing system 240 can be connected to the cloud to optimize the signal processing speed and ensure real-time performance.

[0188] The technical advantage of the above solution is that by combining signal processing and intelligent control technologies through an automated signal processing system, it can adapt to complex and ever-changing noise environments.

[0189] In one embodiment, please refer to Figure 8 and Figure 10 The noise processor 220 also includes a decibel comparator 226, the input of which is electrically connected to the noise collector 210 and the output of which is electrically connected to the first processing submodule 221.

[0190] The decibel comparator 226 is used to acquire the residual motor noise collected in real time by the noise collector 210 after the noise suppressor 230 emits a noise reduction signal, and extract the corresponding noise decibel value from the residual motor noise, so as to compare the noise decibel value with the preset decibel threshold and obtain the decibel comparison result.

[0191] In some embodiments, the first processing submodule 221 is further configured to obtain a decibel comparison result, and when the decibel comparison result is that the noise decibel value is greater than the decibel threshold, to perform speed reduction processing on the drive motor 130, or when the decibel comparison result is that the noise decibel value is less than or equal to the decibel threshold, to end the noise reduction process.

[0192] Specifically, in order to more accurately determine the impact of motor noise on user experience, the decibel value of the motor noise can be obtained. The decibel value of the fan noise can be used to determine whether the motor is operating normally, thus further avoiding the problem of decreased user experience caused by motor abnormalities.

[0193] In some embodiments, the automated signal processing system 240 described above may also include a decibel comparator 226, thereby further improving the active noise reduction technology. The following will provide a detailed analysis of the various parts of the automated signal processing system 240 and its workflow.

[0194] 1. Introduction to System Components

[0195] Noise collector 210 (SignalCollector): Used to collect residual motor noise in the environment in real time, including motor noise that still exists after the noise reduction signal is released by noise suppressor 230.

[0196] Decibel Comparator 226: Used to receive noise signals from noise collector 210, extract the corresponding noise decibel values, compare them with a preset decibel threshold, and generate decibel comparison results.

[0197] The first processing submodule 2215 is used to receive the decibel comparison result output by the decibel comparator 226 and execute control logic to adjust the speed of the fan drive motor 130 to achieve further noise reduction.

[0198] 2. System Workflow

[0199] Signal acquisition: After the noise suppressor 230 emits a noise reduction signal, the noise acquisition unit 210 begins to monitor the residual motor noise in the environment in real time.

[0200] Decibel Extraction and Comparison: The decibel comparator 226 extracts the decibel value of the motor noise from the acquired signal. It then compares the extracted decibel value with a preset decibel threshold and outputs the decibel comparison result. If the decibel value is greater than the threshold, it indicates that the residual motor noise is still strong, and the power or speed of the noise-generating equipment needs to be reduced. If the decibel value is less than or equal to the threshold, it indicates that the noise has been reduced to an acceptable level, and the noise reduction process can be terminated.

[0201] Fan motor control: If the decibel comparison result indicates that the noise decibel value is greater than the decibel threshold, the first processing submodule 2215 will send a control signal to reduce the speed of the drive motor 130. This process can effectively reduce the noise generated by the motor operation.

[0202] Program End: If the decibel comparison result shows that the noise decibel value is less than or equal to the decibel threshold, the program will end and no further noise processing will be performed.

[0203] 3. System Functions

[0204] Dynamic adjustment: The automated signal processing system 240 can dynamically adjust the speed of the fan drive motor 130 according to the changes in real-time residual motor noise, ensuring that the volume is kept to a minimum under various environmental conditions.

[0205] Analogous feedback: Through comparison and real-time feedback, the automated signal processing system 240 can effectively manage and control the response of different noise sources, enhancing the effect of active noise reduction.

[0206] 4. System Settings

[0207] Decibels Threshold Setting: A reasonable decibel threshold setting is crucial for the success of the automated signal processing system 240. A threshold that is too high may cause the fan to slow down ineffectively, while a threshold that is too low may fail to effectively cope with real-world noise environments.

[0208] Fan response time: The first processing submodule 2215 needs to respond as quickly as possible to control the drive motor 130 in order to adapt to the instantaneous changes in environmental noise and thus achieve timely noise reduction.

[0209] The technical advantages of the above solution are: by combining intelligent monitoring, real-time feedback and automatic control technologies through the automated signal processing system 240, it can effectively cope with environmental noise and provide a more comfortable user experience.

[0210] In some embodiments, to further improve energy efficiency, if the automated signal processing system 240 determines that the residual motor noise in the environment is not less than a preset decibel value, noise reduction may not be performed on the motor noise. In specific applications, the automated signal processing system 240 can detect the current usage scenario of the handheld fan 10. If the background noise (including user voice) is high, noise reduction will not be enabled, because enabling noise reduction would definitely result in high power consumption. Therefore, this method can further reduce the power consumption of the mobile phone.

[0211] In other embodiments, to further ensure the stable operation of the handheld fan 10 under low battery conditions, the automated signal processing system 240 can also determine whether the current battery level of the handheld fan 10 is lower than a preset battery level; if so, the drive motor 130 of the handheld fan 10 is started; otherwise, an alarm prompting that the battery level is too low is issued. Therefore, when the battery level is lower than the preset battery level, the automated signal processing system 240 controls the drive motor 130 not to be turned on and can prompt the user to remind them.

[0212] In one implementation of this application, the step of the automated signal processing system 240 to reduce motor noise based on residual motor signals may include: when the motor noise signal contains user voice signals, using a preset noise recognition model to identify the motor noise and obtain a motor noise signal after voice recognition; and then reducing the noise of the motor noise signal after voice recognition. For example, during user operation, interactions between multiple users often occur, requiring voice input. To further improve fan noise recognition and avoid eliminating user voice information, motor noise recognition is necessary. Specifically, the noise recognition model is established by: determining positive and negative input samples, where the positive samples are a noise training set and the negative samples are a voice training set; training with a PLDA model to obtain an average error; and determining a usable motor noise recognition model when the average error is less than a preset error. The PLDA model is trained using positive and negative samples. Once the model reaches a certain maturity level, the automated signal processing system 240 uses the noise recognition model to identify motor noise. This accurately identifies motor noise and reduces the error of mistakenly identifying user voice as motor noise for cancellation, thereby further improving the accuracy of fan noise cancellation and enhancing the user experience.

[0213] In this process, the noise acquisition unit 210 picks up the suppressed residual noise, which is an analog signal. Then, the noise processor 220 amplifies the power of the picked-up analog noise signal and filters out the high-frequency components of the signal using a low-pass filter. The high-frequency filtered signal is then converted from analog to digital and input into the automated signal processing system 240. This process generates low-frequency audio data, which is provided to the automated signal processing system 240 for relearning and evaluation of the active noise reduction effect.

[0214] In one embodiment, please refer to Figure 11 The noise processor 220 also includes an error acquisition device 227, which is disposed in the cavity 101 and electrically connected to the first processing submodule 221. The error acquisition device 227 is used to calculate the error between the motor noise signal and the noise reduction signal, obtain error signal data, and feed the error signal data back to the first processing submodule 221 so that the noise reduction signal can be calibrated by the first processing submodule 221.

[0215] The error acquisition unit 227 is configured to detect the error between the motor noise signal acquired by the noise acquisition unit 210 and the noise reduction signal played by the noise suppressor 230.

[0216] Specifically, in order to improve the noise reduction effect of the handheld fan 10, the handheld fan 10 is also equipped with an error acquisition device 227. The error acquisition device 227 is used to detect the error between the noise signal collected by the noise acquisition device 210 and the noise reduction wave signal played by the noise suppressor 230, and feeds it back to the first processing submodule 221 in the noise processor 220 to calibrate the noise reduction signal, so as to make the inverted signal data in the signal generation instruction generated by the first processing submodule 221 more in line with the noise reduction requirements.

[0217] In some embodiments, the error acquisition unit 227, noise acquisition unit 210, noise suppressor 230, and first processing submodule 221 can form a signal feedback control system 250 based on a signal feedback control mechanism. This signal feedback control system 250 is used to improve the accuracy and effectiveness of the noise reduction system. The following will provide a detailed analysis of each part of this signal feedback control system 250 and its workflow.

[0218] 1. Introduction to System Components

[0219] Error Collector 227: Used to calculate the error between the two in real time, that is, the difference between the actual motor noise signal and the noise-reduced signal generated by the signal processor, generate error signal data and feed it back to the noise processor 220.

[0220] 2. System Workflow

[0221] Signal input: The motor noise signal is captured and input to the first processing submodule 221 for analysis and processing.

[0222] Noise reduction signal generation: The first processing submodule 221 generates a noise reduction signal based on the processed data, which aims to intervene in and reduce the motor noise signal.

[0223] Error Calculation: The error acquisition unit 227 receives the motor noise signal and the noise reduction signal, and calculates the error signal data using a mathematical algorithm (such as subtraction or other error assessment methods). The following formula can be used: Error signal data = Noise signal - Noise reduction signal.

[0224] Data feedback: The calculated error signal data will be fed back to the first processing submodule 221 to provide real-time information on the noise reduction effect.

[0225] Signal calibration: The first processing submodule 221 calibrates the noise-reducing signal based on the feedback error signal data. Parameters such as the amplitude, phase, or frequency of the noise-reducing signal can be adjusted to more effectively combat noise signals. The calibrated noise-reducing signal is then output again to improve the system's noise reduction performance.

[0226] 3. System Functions

[0227] Real-time feedback: The signal feedback control system 250 can quickly respond to the noise reduction effect through the real-time feedback of the error acquisition element 227, thereby making necessary adjustments and improving the noise reduction accuracy.

[0228] Adaptive calibration: The noise processor 220 can dynamically adjust the noise reduction signal based on the error signal calculated in real time, adapting to different noise environments and improving the adaptability and effectiveness of active noise reduction.

[0229] 4. System Settings

[0230] Calculation delay: The delay in error calculation and signal feedback control system 250 may affect the noise reduction effect. Therefore, the response time can be reduced by optimizing the algorithm.

[0231] Noise mode settings: Different motor noise signals may require different noise reduction strategies. Therefore, the noise processor 220 can be designed to flexibly handle various noise modes.

[0232] Environmental adaptability settings: Ensure that the signal feedback control system 250 maintains effective noise reduction under different environmental conditions (such as different types of noise, background changes, etc.).

[0233] The technical advantages of the above solution are as follows: by designing a feedback control system and utilizing the collaborative work of the error acquisition unit and the noise processor, the performance and flexibility of the active noise cancellation system can be significantly improved. This design effectively ensures the real-time performance and accuracy of the noise cancellation signal, enhancing the user experience.

[0234] In one embodiment, the handheld fan 10 includes at least a handheld fan for wireless use, a neckband fan for use around the neck, or a strap-on fan for use in a strap-on configuration.

[0235] Among them, the handheld wireless fan 10 is a portable electric fan featuring a wireless design, allowing users to use it without being restricted by a power cord, making it convenient to carry and use. It is a variant of the handheld mini fan, further emphasizing its wireless characteristics. The main functions of this handheld wireless fan include: ① Wireless portability: Powered by a built-in rechargeable battery, it can be used without being plugged in, suitable for various indoor and outdoor scenarios. ② Multiple wind speed options: This wireless mini fan offers multiple wind speed settings, allowing users to adjust the wind intensity as needed. ③ Convenient charging: This handheld wireless mini fan can be charged via a USB interface, making it convenient to connect to a power bank or computer for charging. ④ Multifunctional: This handheld fan can include additional functions such as a misting function, LED light, or even a Bluetooth speaker. ⑤ Easy storage: Its lightweight design makes it easy to put in a bag, ideal for travel use.

[0236] Neck-hanging fans are portable fans that can be worn around the neck. This design allows the fan to be close to the body, providing a more direct cooling effect, making it ideal for hot summers or outdoor activities. The main functions of a neck-hanging fan include: ① Hands-free use: Because it hangs around the neck, the user's hands are free to use, without having to hold the fan. ② Portability: Its lightweight design makes it easy to carry, suitable for use in various situations such as travel, sports, and work. ③ Multiple wind speeds: The neck-hanging fan offers multiple wind speed settings, allowing users to choose different speeds as needed. ④ Charging function: The neck-hanging fan can be charged via USB interface, using a power bank or computer. ⑤ 360-degree rotation: The neck-hanging fan can be designed with adjustable airflow direction, allowing the fan angle to be freely rotated to meet individual needs.

[0237] One type of portable fan is the strap-on fan, a uniquely designed feature typically used to secure itself to a specific location or object, providing airflow or cooling. This type of fan is particularly suitable for special occasions such as outdoor camping, cycling, or use in fixed work environments. The main functions of this strap-on fan include: ① Secure use: The fan can be fixed to chairs, tents, sheds, etc., using straps, clips, or other securing devices for extended use. ② Adjustable wind speed: This type of strap-on fan offers multiple wind speed settings, allowing users to select different settings according to their needs. ③ Versatile application: This type of strap-on fan is suitable for various scenarios such as outdoor activities, camping, sports, and home use. ④ Portable charging: This type of strap-on fan features a USB charging design for easy portability and charging.

[0238] Figure 12 This is a block diagram of a computer-readable storage medium 30 provided in an embodiment of this application. The computer-readable storage medium 30 stores a computer program 31, wherein when the computer program 31 is executed by the processor 31, it implements the active noise reduction program, the automated signal processing program, and the signal feedback control program for the drive motor 130 as described above.

[0239] If the integrated units of the various functional units in the various embodiments of this application are implemented as software functional units and sold or used as independent products, they can be stored in the computer-readable storage medium 30. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer-readable storage medium 30 includes a computer program 31, which includes several instructions to cause a computer device (which may be a personal computer, system server, or network device, etc.), an electronic device (e.g., a handheld electric fan, or a desktop fan, wearable fan, etc.), or a processor to execute all or part of the steps of the methods of the various embodiments of this application.

[0240] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0241] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A noise reduction device for a handheld fan motor, characterized in that, The handheld fan includes an air delivery section and a handheld section, and a drive motor is disposed inside the air delivery section; the motor noise reduction device includes: A noise collector is installed inside the air supply section to collect the motor noise generated by the handheld fan during operation in real time; the motor noise includes the mechanical vibration noise, electromagnetic noise and aerodynamic noise of the drive motor. A noise processor, disposed on the handheld unit and electrically connected to the noise collector, is used to generate a noise control command based on the motor noise when the signal strength of the motor noise is greater than the strength threshold. A noise suppressor is disposed inside the air supply section and electrically connected to the noise processor. It is used to acquire the noise control command and issue a noise reduction signal according to the noise control command to cancel the interference of the motor noise.

2. The motor noise reduction device for a handheld fan according to claim 1, characterized in that, The air supply unit is also provided with an impeller assembly, which includes a hub and a plurality of fan blades spaced apart on the outer surface of the hub. The hub includes a conical cavity for enclosing and fixing the drive motor.

3. The motor noise reduction device for a handheld fan according to claim 2, characterized in that, The noise collector includes: The first microphone is located on the inner wall of the conical cavity and is used to collect the electromagnetic noise generated by the drive motor during operation. The second microphone is located on the outer surface of the hub and is used to collect the aerodynamic noise generated by the drive motor during operation. The third microphone is mounted on the drive motor and is used to collect the mechanical vibration noise generated by the drive motor during operation.

4. The motor noise reduction device for a handheld fan according to claim 3, characterized in that, The noise processor includes: The first processing submodule is used to perform frame segmentation, windowing and time-frequency transformation processing on the mechanical vibration noise, the electromagnetic noise and the aerodynamic noise respectively to obtain multiple corresponding frequency domain noise frames; The first determining submodule is used to determine the noise suppression frame corresponding to each of the motor noises. The plurality of noise suppression frames correspond one-to-one with the plurality of frequency domain noise frames, and the corresponding noise suppression frames and frequency domain noise frames have opposite phases, the same amplitude and frequency. The second determining submodule is used to determine the compensation gain corresponding to each frequency within the target frequency range based on the motor speed and vibration frequency of the drive motor, the air supply speed and the number of fan blades of the air supply section; the target frequency range is the frequency range in which the noise of each motor is located. The first generation submodule is used to generate noise control commands for the mechanical vibration noise, the electromagnetic noise and the aerodynamic noise based on each of the noise suppression frames and the compensation gain corresponding to each frequency in the target frequency range.

5. The motor noise reduction device for a handheld fan according to claim 4, characterized in that, The noise suppressor includes a power amplifier and an audio player; The power amplifier is used to acquire noise control commands for the mechanical vibration noise, the electromagnetic noise and the aerodynamic noise respectively, and amplify the noise reduction data carried by the various noise control commands to obtain the corresponding power amplification signal; The audio player is used to emit noise reduction signals that are opposite in phase but have the same frequency and amplitude as the various motor noises, based on the power amplification signal.

6. The motor noise reduction device for a handheld fan according to claim 5, characterized in that, The audio player includes: A first player is disposed on the inner wall of the conical cavity and corresponds to the first microphone, used to acquire a power amplified signal for the electromagnetic noise in order to play the first noise-reduced signal; A second player is disposed on the outer surface of the hub and corresponds to the second microphone, for acquiring a power amplified signal for the aerodynamic noise in order to play the second noise-reduced signal; A third player, mounted on the drive motor and corresponding to the third microphone, is used to acquire a power-amplified signal for the mechanical vibration noise in order to play a third noise-reduced signal.

7. The motor noise reduction device for a handheld fan according to claim 4, characterized in that, The noise processor further includes an amplitude comparator, the input of which is electrically connected to the noise collector, and the output of which is electrically connected to the first processing submodule. The amplitude comparator is used to acquire various types of motor noise and extract the corresponding noise amplitude sequence from the motor noise, so as to compare the noise amplitude sequence with a preset amplitude threshold to obtain the amplitude comparison result. The first processing submodule is further configured to obtain the amplitude comparison result, and when the amplitude comparison result indicates that the noise amplitude sequence is greater than the amplitude threshold, generate a noise control command based on the motor noise; or, when the amplitude comparison result indicates that the noise amplitude sequence is less than or equal to the amplitude threshold, terminate the noise reduction program.

8. The motor noise reduction device for a handheld fan according to claim 4, characterized in that, The noise processor further includes a decibel comparator, the input of which is electrically connected to the noise collector and the output of which is electrically connected to the first processing submodule. The decibel comparator is used to acquire the residual motor noise collected in real time by the noise collector after the noise suppressor emits the noise reduction signal, and extract the corresponding noise decibel value from the residual motor noise, so as to compare the noise decibel value with a preset decibel threshold to obtain the decibel comparison result. The second processing submodule is used to obtain the decibel comparison result, and when the decibel comparison result is that the noise decibel value is greater than the decibel threshold, to reduce the speed of the drive motor, or when the decibel comparison result is that the noise decibel value is less than or equal to the decibel threshold, to end the noise reduction program.

9. The motor noise reduction device for a handheld fan according to claim 8, characterized in that, The noise processor further includes an error acquisition device, which is disposed inside the air supply section and electrically connected to the first processing submodule. The error acquisition device is used to calculate the error between the motor noise and the motor noise, obtain error signal data, and feed the error signal data back to the first processing submodule to calibrate the noise reduction signal.

10. The motor noise reduction device for a handheld fan according to any one of claims 1-9, characterized in that, The drive motor is a three-phase high-speed micro motor with an operating speed exceeding a preset speed; wherein, the preset speed is 12,000 rpm.

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