Air conditioner outdoor unit vibration noise control method and system

Abstract

The application relates to the technical field of air conditioners, and discloses an air conditioner outdoor unit vibration noise control method and system, which aims to solve the problem of poor noise reduction effect of the existing method, and mainly comprises the following steps: optimizing the design of a fan to reduce the rotating speed and divide gears, and determining the rotating speed values of the gears according to low-frequency noise optimization; adopting a finite element method to optimize compressor pipeline parameters, so that the number of resonance peak values in the full frequency band meets preset conditions; obtaining stress values of each frequency point through a pipeline vibration stress experiment, applying torque compensation to the frequency points exceeding a threshold value, finding optimal parameters, shielding frequency points still exceeding the threshold value after compensation, and determining qualified frequency points of pipeline vibration; checking compressor and fan coupling noise and sheet metal resonance noise, shielding abnormal frequency points or optimizing the sheet metal structure, and determining the final operating frequency of the compressor. The application realizes all-around active control from a vibration source to a propagation path, and ensures that the vibration noise of the air conditioner outdoor unit during full-frequency operation is effectively inhibited.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, specifically to a method and system for controlling vibration and noise of an outdoor air conditioning unit. Background Technology

[0002] Air conditioner outdoor units generate vibration and noise during operation, affecting user comfort and negatively impacting the long-term reliable operation of the air conditioner itself. The vibration and noise of the outdoor unit mainly originate from two core components: the compressor and the axial fan. These two components have different vibration mechanisms and noise characteristics. When the axial fan operates, the rotating blades cut the airflow, generating periodic rotational noise and broadband turbulent noise, manifested as a noticeable "whooshing" sound. The higher the fan speed and the worse the blade dynamic balance, the more pronounced the vibration and noise problems become. The compressor is the main source of low-frequency vibration and structural noise in the outdoor unit. Its internal high-speed mechanical components generate significant reciprocating inertial forces and torque fluctuations during the periodic compression of the refrigerant. These vibrations are transmitted through the compressor's vibration damping system to the casing, base, and connected copper pipes, causing vibration of sheet metal parts and piping, and radiating low-frequency "humming" noise. Although variable frequency compressors can reduce vibration at certain frequencies, controlling the vibration characteristics across the entire frequency range remains a technical challenge. In addition, the vibration noise of the compressor and the fan can couple and be amplified under certain conditions. When their frequencies are close, they can easily cause severe beat frequency noise, which further deteriorates the noise performance.

[0003] In the prior art, the following measures are usually taken to reduce the vibration and noise of the outdoor unit of an air conditioner: optimizing the design of the fan blades (such as adjusting the blade angle and improving the dynamic balance) to reduce rotational noise; installing shock-absorbing pads at the bottom of the compressor to reduce vibration transmission; adjusting the pipeline route or adding damping blocks to reduce pipeline vibration; and pasting passive sound insulation materials such as sound-absorbing cotton on the inner wall of the casing.

[0004] However, these existing technologies are mostly single-faceted optimizations or passive noise reductions, making it difficult to comprehensively solve the complex vibration and noise problems of air conditioner outdoor units operating across the entire frequency band. On the one hand, the vibration characteristics of variable frequency compressors vary significantly at different frequencies, and existing technologies often only optimize for specific frequencies, failing to guarantee effective suppression of vibration at all frequency points across the entire frequency band. On the other hand, the vibration and noise generated by the compressor and fan are coupled through structural transmission and airflow disturbances, and conventional methods struggle to effectively control this coupling effect. Therefore, existing noise control solutions still fall short in terms of overall noise reduction performance, and the user experience needs further improvement. Summary of the Invention

[0005] This invention aims to solve the problem of poor noise reduction effect in existing air conditioning noise control schemes, and proposes a method and system for controlling the vibration and noise of air conditioning outdoor units.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] In a first aspect, the present invention provides a method for controlling vibration and noise of an outdoor unit of an air conditioner, the method comprising:

[0008] Step S1: Execute the fan control strategy: Optimize the fan design, reduce the fan speed while increasing the air volume, ensure that the highest speed is less than or equal to the preset speed threshold, and divide the fan into multiple speed levels. Determine the speed value corresponding to each level based on the principle of optimal low-frequency noise.

[0009] Step S2: Optimize the compressor piping: Use the finite element method to perform response analysis on the compressor piping, obtain the piping response curve of the compressor piping, and adjust the piping parameters based on the piping response curve until the number of resonance peaks in the entire frequency band of the air conditioner meets the preset conditions.

[0010] Step S3: Perform compressor torque compensation control: Conduct a pipeline vibration stress test on the optimized compressor pipeline to obtain the pipeline vibration stress value at each sweep frequency point; apply compressor torque compensation to the frequency points where the pipeline vibration stress value exceeds the preset judgment threshold, and find the optimal torque compensation control parameters; perform frequency hopping shielding on the frequency points where the pipeline vibration stress still exceeds the preset judgment threshold under the optimal torque compensation control parameters, thereby determining the qualified frequency points of compressor pipeline vibration.

[0011] Step S4: Determine the final operating frequency of the compressor: Based on the determined qualified frequency points of compressor pipeline vibration, conduct noise investigation of compressor-fan coupling and noise investigation of compressor-air conditioner outdoor unit sheet metal resonance, perform frequency hopping shielding on the abnormal frequency points found, and / or optimize the sheet metal structure that causes resonance, and finally determine the final operating frequency of the compressor.

[0012] Furthermore, in step S1, the optimization design of the fan includes:

[0013] The fan blade installation angle is controlled to be greater than or equal to 25°;

[0014] The axial projected area of ​​the axial flow fan blades is greater than 70% of the area of ​​a circular axial flow fan of the same diameter;

[0015] Control the dynamic balance value of the fan blades to be less than 0.03;

[0016] Modal control of the wind turbine blade structure is performed to ensure that the natural frequency of the wind turbine blade mode avoids the driving frequency of the motor power supply and its harmonics, so as to avoid resonance between the wind turbine blade and the power supply excitation.

[0017] Further, in step S1, the preset speed threshold is 750 r / min; determining multiple fan speed levels and their corresponding speed values ​​specifically includes:

[0018] The number of fan speed settings is determined to be 8;

[0019] The speed ranges for each gear are set as follows: 1st gear is 350-400 r / min, 2nd gear is 400-450 r / min, 3rd gear is 450-500 r / min, 4th gear is 500-550 r / min, 5th gear is 550-600 r / min, 6th gear is 600-650 r / min, 7th gear is 650-700 r / min, and 8th gear is 700-750 r / min.

[0020] Further, in step S2, the full frequency band of the air conditioner is 6Hz-110Hz; the preset condition is that the number of resonance peaks in the full frequency band is less than 3; the adjustment of pipeline parameters includes at least one of the following: adjusting pipeline length, bending radius, and pipeline direction.

[0021] Furthermore, in step S3, the specific process of conducting the pipeline vibration stress test includes:

[0022] Under the maximum cooling and maximum heating conditions of the air conditioner, at least one test point shall be arranged at the bend of each component of the compressor pipeline; wherein, each component includes the suction pipe, the discharge pipe, the condenser connecting pipe, and the shut-off valve connecting pipe.

[0023] Frequency sweep tests were conducted at 1Hz intervals within a frequency range of 6Hz to 110Hz, and the pipeline vibration stress values ​​at each test point under each sweep frequency were output.

[0024] Furthermore, in step S3, the preset judgment threshold is 12 MPa;

[0025] The process of finding the optimal torque compensation control parameters includes: if the pipeline vibration stress value at each test point is greater than 12MPa at a certain frequency, then by adding a compensation current signal to the inverter control signal, and by adjusting the angle parameter of the compressor torque compensation and the current loading parameter of 10%-100%, the optimal torque compensation control parameters at that frequency point are found.

[0026] Furthermore, in step S4, the process of investigating the coupling noise between the compressor and the fan includes:

[0027] By testing the beat frequency noise caused by the compressor speed and operating frequency of the outdoor unit of the air conditioner during full-frequency operation in a fully anechoic chamber, the first noise spectrum at each frequency point was obtained.

[0028] The sound pressure level of the noise peak in the first noise spectrum is extracted and compared with the total noise value. If the difference between the two is less than 10dB, the frequency point is deemed qualified; otherwise, it is deemed an abnormal frequency point and the compressor frequency point is blocked.

[0029] Furthermore, in step S4, the process of troubleshooting the resonance noise between the compressor and the outdoor unit of the air conditioner includes:

[0030] The resonance noise caused by the outdoor unit compressor and the sheet metal parts of the outdoor unit during the full-frequency operation of the air conditioner was tested in a fully anechoic chamber, and the second noise spectrum at each frequency point was obtained.

[0031] The sound pressure level of the noise peak in the second noise spectrum is extracted and compared with the total noise value. If the difference between the two is less than 10dB, the frequency point is deemed qualified; otherwise, it is deemed an abnormal frequency point and the step of optimizing the sheet metal structure is executed to reduce noise radiation.

[0032] Furthermore, the optimization of the sheet metal structure that causes resonance includes one or more of the following methods: increasing the sheet metal wall thickness, adjusting the shape and number of sheet metal reinforcing ribs, and attaching damping blocks to the inside of the air conditioning sheet metal structural components.

[0033] In a second aspect, the present invention provides a vibration and noise control system for an air conditioner outdoor unit, used to implement the vibration and noise control method for an air conditioner outdoor unit as described in the first aspect, the system comprising:

[0034] The fan control strategy execution module is used to execute the fan control strategy: optimize the design of the fan, reduce the fan speed while increasing the air volume, ensure that the highest speed is less than or equal to the preset speed threshold, and divide the fan speed into multiple speed levels, determining the speed value corresponding to each level based on the principle of optimal low-frequency noise.

[0035] The compressor pipeline optimization module is used to perform response analysis on the compressor pipeline using the finite element method, obtain the pipeline response curve of the compressor pipeline, and adjust the pipeline parameters based on the pipeline response curve until the number of resonance peaks in the entire frequency band of the air conditioner meets the preset conditions.

[0036] The compressor torque compensation control module is used to conduct pipeline vibration stress experiments on the optimized compressor pipeline to obtain the pipeline vibration stress value at each sweep frequency point; apply compressor torque compensation to the frequency points where the pipeline vibration stress value exceeds a preset judgment threshold, and find the optimal torque compensation control parameters; and perform frequency hopping shielding on the frequency points where the pipeline vibration stress still exceeds the preset judgment threshold under the optimal torque compensation control parameters, thereby determining the qualified frequency points of compressor pipeline vibration.

[0037] The final operating frequency determination module is used to investigate the coupling noise between the compressor and the fan and the resonance noise between the compressor and the outdoor unit of the air conditioner, based on the determined qualified frequency points of compressor pipeline vibration. It performs frequency hopping shielding on the abnormal frequency points found and / or optimizes the sheet metal structure that causes resonance, and finally determines the final operating frequency of the compressor.

[0038] The beneficial effects of this invention are as follows: The vibration and noise control method and system for outdoor air conditioning units provided by this invention reduce fan speed while ensuring airflow through optimized fan design, thereby reducing fan excitation at the source; optimize pipeline parameters using the finite element method to reduce pipeline resonance peaks across the entire frequency band; effectively suppress compressor pipeline vibration through torque compensation control and frequency hopping shielding; and finally, prevent the mutual amplification of compressor and fan vibrations through coupling noise and sheet metal resonance investigation. Through the above multi-level control strategies, this invention systematically solves the vibration and noise problem of outdoor air conditioning units operating across the entire frequency band, achieving comprehensive active control from the vibration source to the propagation path, ensuring effective suppression of vibration and noise of the outdoor air conditioning unit during full-frequency operation, and significantly improving product operational stability and user comfort. Attached Figure Description

[0039] Figure 1 A flowchart illustrating a vibration and noise control method for an outdoor unit of an air conditioner, provided as an example;

[0040] Figure 2 A schematic diagram of the fan blade installation angle provided for an embodiment;

[0041] Figure 3 A schematic diagram of the axial projection area of ​​an axial fan blade provided for an embodiment;

[0042] Figure 4 A schematic diagram of the finite element model of the compressor piping provided for an embodiment;

[0043] Figure 5 A schematic diagram of axial and radial vibration test data curves of the compressor at different operating frequencies provided in the embodiment;

[0044] Figure 6 This is a schematic diagram of the vibration and noise control system for an outdoor air conditioning unit provided in an embodiment. Detailed Implementation

[0045] Since existing technologies mostly involve single-point optimization or passive noise reduction, they are insufficient to comprehensively address the complex vibration and noise issues of air conditioner outdoor units operating across the entire frequency band. Therefore, this invention proposes a technical solution. Firstly, the fan design is optimized at its source. While ensuring airflow, the fan speed is reduced and speed settings are rationally configured to decrease the aerodynamic noise generated by the fan itself. Secondly, the compressor piping structure is optimized using the finite element method. By adjusting piping parameters, resonance peaks across the entire frequency band are reduced, weakening pipe vibration along the propagation path. Furthermore, risk frequency points exceeding stress limits are identified through pipe vibration stress experiments. Torque compensation control is applied to these frequency points to actively suppress compressor vibration. Frequency points that still fail to meet standards after compensation are frequency-hopping shielded to ensure the reliability of the compressor piping during full-frequency operation. Finally, the beat noise generated by the coupling between the compressor and fan, as well as resonance noise with sheet metal components, are comprehensively investigated. Abnormal frequency points are shielded or structurally optimized to determine the optimal operating frequency of the compressor, achieving comprehensive vibration and noise control of the entire unit under all operating conditions.

[0046] The technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0047] Figure 1 A schematic diagram of vibration and noise control for an air conditioner outdoor unit is shown. Please refer to [link / reference]. Figure 1 The method includes the following steps:

[0048] Step S1: Execute the fan control strategy: Optimize the fan design, reduce the fan speed while increasing air volume, ensure that the highest speed is less than or equal to the preset speed threshold, and divide the fan speed into multiple speed levels. Determine the speed value corresponding to each level based on the principle of optimal low-frequency noise.

[0049] This step aims to reduce vibration and noise from the fan side at the source. Specifically, by optimizing the fan design, the fan speed is reduced while increasing airflow, thereby reducing aerodynamic noise and mechanical vibration generated by the fan rotation. At the same time, by rationally dividing the fan speed into gears and determining the corresponding speed values ​​for each gear based on the principle of optimal low-frequency noise, it is ensured that the fan maintains a low noise level under different operating conditions.

[0050] To ensure that airflow is not reduced while speed is decreased, this embodiment optimizes the fan design in the following aspects:

[0051] (1) Control the installation angle of the fan blades to be greater than or equal to 25°.

[0052] Specifically, the fan blade installation angle (also known as the angle of attack) is a key parameter affecting airflow. Increasing the installation angle enhances the fan blade's ability to perform work on the airflow, thus achieving a larger airflow at the same rotational speed, or allowing for a lower fan speed to meet the same airflow demand. For example... Figure 2 As shown, the air volume increases significantly with the increase of the installation angle. This embodiment requires the fan blade installation angle to be greater than or equal to 25° to ensure that the air volume requirements of the air conditioning system can still be met after reducing the fan speed.

[0053] Tables 1 and 2 show the measured noise and airflow data of the fan at various speed settings under two different blade tip heights (120mm and 146mm) with a blade diameter of 560mm, respectively. This is used to illustrate the positive effect of increasing the blade installation angle (reflected in the increase of blade tip height) on improving airflow and reducing noise.

[0054] Table 1. Measured data of noise and air volume of the fan at various speeds with a blade tip height of 120mm.

[0055]

[0056] Table 2. Measured noise and air volume data of the fan at various speed settings under a design blade tip height of 146mm.

[0057]

[0058] The data above shows that increasing the blade tip height to increase the blade installation angle can achieve the following technical effects:

[0059] ① Lower rotation speed for the same air volume: to reach approximately 2370 The optimized design (146mm blade height) requires only 500r / min for airflow, while the original design (120mm blade height) requires 620r / min, a reduction of approximately 19%.

[0060] ② Greater air volume at the same speed: At a speed of about 810 r / min, the optimized design increases the air volume by about 9.6% compared to the original design.

[0061] ③ Lower noise level with the same airflow: to reach approximately 4320 The maximum airflow is reduced, and the optimized design reduces noise by approximately 6.6 dB compared to the original design, demonstrating a significant noise reduction effect.

[0062] (2) Control the axial projection area of ​​the axial fan blades to be greater than 70% of the area of ​​the same diameter circle of the axial fan.

[0063] Specifically, the projected area of ​​the axial fan blades directly affects its work capacity. A larger projected area means a larger contact area between the blades and the airflow, resulting in a larger air volume at the same rotational speed. For example... Figure 3 As shown, this embodiment requires that the projected area of ​​the axial fan blades in the axial direction be greater than 70% of the area of ​​a circular axial fan of the same diameter, in order to increase the air volume and create conditions for reducing the rotational speed.

[0064] (3) Control the dynamic balance value of the wind turbine blades to be less than 0.03.

[0065] Specifically, poor dynamic balance of the fan blades will exacerbate the vibration and noise of the outdoor unit. This embodiment strictly controls the dynamic balance value of the fan blades to be less than 0.03, reducing mechanical vibration caused by dynamic balance problems.

[0066] (4) Perform wind turbine structure mode control so that the wind turbine mode natural frequency avoids the motor power drive frequency and its harmonics, so as to avoid resonance between the wind turbine and the power excitation.

[0067] Specifically, as an elastic structure, the wind turbine blade has its natural frequency. If the natural frequency of the wind turbine blade's modal is close to the driving frequency of the motor power supply (e.g., 50Hz) or its harmonics (100Hz, 150Hz, 200Hz), resonance is easily triggered, amplifying vibration noise. This embodiment uses modal control to ensure that the natural frequency of the wind turbine blade's modal avoids the aforementioned frequency points, thus preventing resonance between the wind turbine blade and the power supply excitation.

[0068] After optimizing the fan design, the fan can meet the airflow requirements at a lower speed. In this embodiment, the highest speed setting of the outdoor unit is controlled below 750 r / min, which is used as the preset speed threshold.

[0069] Based on this, in order to precisely control the fan's operating status while also considering low-frequency noise performance, this embodiment divides the fan speed into 8 levels, and the speed range of each level is set as follows:

[0070] The speed ranges are as follows: 1st gear: 350-400 rpm; 2nd gear: 400-450 rpm; 3rd gear: 450-500 rpm; 4th gear: 500-550 rpm; 5th gear: 550-600 rpm; 6th gear: 600-650 rpm; 7th gear: 650-700 rpm; 8th gear: 700-750 rpm.

[0071] Within each speed range, the specific speed value is determined based on the principle of optimal low-frequency noise. Low-frequency noise is usually related to frequency components that are more sensitive to the human ear. Through experimental testing or simulation analysis, the speed point with the best noise performance within each speed range is selected as the calibration speed for that speed, ensuring that the noise of the fan is minimized during operation.

[0072] The above-mentioned fan control strategy ensures that the fan operates at the lowest possible speed while meeting the system's air volume requirements. Furthermore, by controlling key design parameters and optimizing gear settings, the vibration and noise on the fan side are significantly reduced.

[0073] Step S2: Optimize the compressor piping: Use the finite element method to perform response analysis on the compressor piping, obtain the piping response curve of the compressor piping, and adjust the piping parameters based on the piping response curve until the number of resonance peaks in the entire frequency band of the air conditioner meets the preset conditions.

[0074] In this invention, the air conditioner's full frequency band is 6Hz-110Hz; the preset condition is that the number of resonance peaks within the full frequency band is less than 3; the adjusted pipeline parameters include at least one of the following: adjusted pipeline length, bending radius, and pipeline direction.

[0075] In practical applications, the first step is to establish a finite element model of the compressor piping, such as... Figure 4 As shown, the compressor includes components such as the intake pipe, exhaust pipe, condenser connection pipe, and shut-off valve connection pipe. The frequency response of the compressor piping is analyzed using the finite element method to simulate the compressor's vibration response at different operating frequencies.

[0076] Specifically, a unit excitation load is applied at the connection point between the compressor and the pipeline, and the vibration response of the compressor pipeline in the frequency range of 6Hz to 110Hz is calculated. The vibration displacement or stress amplitude corresponding to each frequency point is output, thereby obtaining the pipeline response curve. This pipeline response curve can intuitively reflect the vibration amplification characteristics of the compressor pipeline at different frequencies, and the position of the peak on the curve is the resonant frequency point of the pipeline.

[0077] Then, based on the response analysis results, the number of resonance peaks within the entire frequency band (6Hz-110Hz) of the air conditioner is counted. In this embodiment, the preset condition is that the number of resonance peaks within the entire frequency band is less than 3, which means that the compressor pipeline does not have too many resonance frequencies within the compressor's operating frequency range, in order to avoid vibration amplification at multiple frequency points at the same time.

[0078] If the analysis results show that the number of resonance peaks does not meet the above preset conditions, then the pipeline parameters need to be adjusted and optimized. Adjustable pipeline parameters include:

[0079] (1) Pipe length: Changing the pipe length can adjust its acoustic standing wave frequency and structural natural frequency. Generally, shortening the pipe can increase the resonant frequency, while lengthening the pipe can decrease the resonant frequency.

[0080] (2) Bending radius: Adjusting the curvature radius of the pipe bend will affect the local stiffness and stress distribution, thereby changing the modal frequency;

[0081] (3) Pipeline routing: Changing the arrangement path of pipelines in three-dimensional space can adjust the stiffness distribution and mass distribution of the entire pipeline system, thereby changing its modal characteristics.

[0082] By combining one or more of the above methods for optimization, finite element response analysis was performed again until the number of resonance peaks in the compressor pipeline across the entire frequency band of 6Hz-110Hz was less than 3. The optimized pipeline response curve is smoother across the entire frequency band, and the resonance peaks are effectively suppressed.

[0083] Through the above-mentioned pipeline optimization design, the compressor pipeline is ensured to have good vibration resistance characteristics across the entire frequency range, laying the foundation for subsequent torque compensation control and frequency determination.

[0084] Step S3: Perform compressor torque compensation control: Conduct a pipeline vibration stress test on the optimized compressor pipeline to obtain the pipeline vibration stress value at each sweep frequency point; apply compressor torque compensation to the frequency points where the pipeline vibration stress value exceeds the preset judgment threshold, and find the optimal torque compensation control parameters; perform frequency hopping shielding on the frequency points where the pipeline vibration stress still exceeds the preset judgment threshold under the optimal torque compensation control parameters, thereby determining the qualified frequency points of compressor pipeline vibration.

[0085] Step S2 optimized the pipeline structure through finite element simulation. However, due to the complexity of actual operating conditions, the simulation results could not fully cover all operating states. This step uses pipeline vibration stress experiments to accurately measure the stress response of the pipeline at various frequency points. Torque compensation control is applied to frequency points that exceed the safety threshold, thereby actively suppressing vibration and ensuring the reliability of the pipeline in operation across the entire frequency band.

[0086] In this embodiment, a pipeline vibration stress test is first conducted on the compressor pipeline optimized in step S2 to obtain the stress values ​​of key parts of the pipeline at various frequency points. The specific process of the pipeline vibration stress test includes:

[0087] (1) Experimental conditions and test point arrangement: Under the maximum cooling and maximum heating conditions of the air conditioner, at least one test point shall be arranged at the bend of each component of the compressor pipeline; wherein, each component includes the suction pipe, the exhaust pipe, the condenser connecting pipe and the shut-off valve connecting pipe.

[0088] Specifically, experiments were conducted under the maximum cooling and maximum heating conditions of the air conditioner. These two conditions represent the heaviest operating load for the compressor, resulting in the most significant pipe vibration stress. At least one test point was placed at each bend in the compressor piping. Bends are typically stress concentration areas and risk points for pipe fatigue failure; therefore, the suction pipe, discharge pipe, condenser connection pipe, and shut-off valve connection pipe were the key monitoring targets.

[0089] (2) Frequency sweep test: Perform frequency sweep test in the frequency range of 6Hz to 110Hz at 1Hz intervals, and output the pipeline vibration stress value at each test point under each frequency sweep.

[0090] Specifically, the compressor is controlled to operate within a frequency range of 6Hz to 110Hz, and frequency sweep tests are performed point-by-point at 1Hz intervals. At each frequency point, the pipeline vibration stress value at each test point is recorded, and the stress data of all test points at each swept frequency point are output. Through frequency sweep testing, the stress response spectrum of the compressor pipeline across the entire frequency band can be obtained, and the frequency points where stress exceeds the limit can be identified.

[0091] Then, torque compensation control and optimal torque compensation parameter optimization are performed.

[0092] Figure 5 The diagram shows test data curves for axial and radial vibration of a compressor at different operating frequencies without torque compensation. Please refer to [link / reference]. Figure 5 At all operating frequencies, the radial vibration value was significantly greater than the axial vibration value, verifying that the compressor vibration was mainly caused by the tangential vibration resulting from the imbalance between the driving torque and the resistance torque. At the same time, the vibration value fluctuated significantly with frequency, with peak values ​​appearing at frequencies such as 650Hz and 1000Hz. Figure 5 The measured data demonstrates the vibration characteristics of the compressor during operation across the entire frequency range. Actively suppressing tangential vibration through torque compensation and implementing differentiated control at different frequency points are effective ways to reduce compressor vibration.

[0093] In this embodiment, the preset judgment threshold is 12MPa; the process of finding the optimal torque compensation control parameters includes: if the pipeline vibration stress value at each test point is greater than 12MPa at a certain frequency, then by adding a compensation current signal to the inverter control signal, and by adjusting the angle parameter of the compressor torque compensation and the current loading parameter of 10%-100%, the optimal torque compensation control parameters at that frequency point are found.

[0094] Specifically, compressor vibration can be divided into radial and axial directions, with tangential vibration, caused by the imbalance between the driving torque and the gas resistance torque, contributing the most to the vibration. This imbalance causes speed fluctuations; the greater the angular acceleration, the greater the vibration. The basic principle of compressor torque compensation control is to add a compensation current signal to the inverter control signal, superimpose this signal on the compressor control signal, and use the superimposed current control signal to drive the compressor motor. This makes the driving torque and resistance torque more consistent, reducing speed fluctuations and thus suppressing vibration.

[0095] The compensation current signal contains two key parameters: the compensation angle parameter and the compensation current loading ratio. The angle parameter determines the phase of the compensation signal relative to the rotor position, while the current loading ratio determines the amplitude of the compensation signal.

[0096] For the frequency points where stress exceeds the standard found in the frequency sweep test, this embodiment adopts the following steps to optimize torque compensation:

[0097] First, at a certain frequency, if the pipeline vibration stress value at any test point is greater than 12MPa, then that frequency point is determined to be a stress-exceeding frequency point, and torque compensation control needs to be applied.

[0098] Then, for each frequency point where stress exceeds the limit, the optimal torque compensation control parameters at that frequency point are found by adjusting the angle parameter and current loading ratio of the compressor torque compensation. The current loading ratio is adjustable within the range of 10% to 100%. Specifically, the compressor is run at that frequency point, and the angle parameter and current loading ratio are gradually adjusted. The stress value changes at each test point are observed, and the parameter combination that reduces the stress value at all test points to the lowest level below 12MPa is selected as the optimal torque compensation control parameter for that frequency point.

[0099] Finally, after applying the optimal torque compensation control parameters, the stress values ​​at each test point at that frequency are measured again. If the stress values ​​at all test points drop below 12 MPa, then that frequency point is determined to be a qualified frequency point and remains within the compressor's operating frequency range.

[0100] For frequency points where the stress value exceeds 12MPa even under optimal torque compensation control parameters, it indicates that the pipeline vibration stress at that frequency point cannot be effectively suppressed by torque compensation. To avoid fatigue damage to the pipeline due to excessive long-term vibration stress, this embodiment implements frequency hopping shielding for such frequency points. That is, the frequency point is removed from the available operating frequencies of the compressor through the air conditioner outdoor unit frequency control system, prohibiting the compressor from operating at that frequency point.

[0101] Through the above process, this embodiment ultimately determined a set of qualified frequency points for compressor pipeline vibration. These frequency points can meet the pipeline vibration stress requirements across the entire frequency range, ensuring the operational reliability of the pipeline system.

[0102] Step S4: Determine the final operating frequency of the compressor: Based on the determined qualified frequency points of compressor pipeline vibration, conduct noise investigation of compressor-fan coupling and noise investigation of compressor-air conditioner outdoor unit sheet metal resonance, perform frequency hopping shielding on the abnormal frequency points found, and / or optimize the sheet metal structure that causes resonance, and finally determine the final operating frequency of the compressor.

[0103] Step S3, through pipeline vibration stress testing and torque compensation control, has screened out a set of qualified frequency points that meet the pipeline reliability requirements. However, when the compressor operates at these frequency points, it may also generate coupled vibrations and noises with other components, such as beat frequency noise generated with the fan and resonance noise generated with sheet metal parts.

[0104] Based on this, this step aims to comprehensively consider the coupling effect between the compressor and other components of the whole machine, and through the investigation and optimization of coupling noise, finally determine the usable frequency point of the compressor in actual operation, so as to ensure that the noise level of the whole machine meets the requirements when the compressor is running in the full frequency band.

[0105] In this embodiment, the process of troubleshooting the coupling noise between the compressor and the fan includes:

[0106] By testing the beat frequency noise caused by the compressor speed and operating frequency of the outdoor unit of the air conditioner during full-frequency operation in a fully anechoic chamber, the first noise spectrum at each frequency point was obtained.

[0107] The sound pressure level of the noise peak in the first noise spectrum is extracted and compared with the total noise value. If the difference between the two is less than 10dB, the frequency point is deemed qualified; otherwise, it is deemed an abnormal frequency point and the compressor frequency point is blocked.

[0108] Specifically, the compressor and fan are the two main vibration sources of the outdoor unit of an air conditioner. When their operating frequencies are close, beat frequency noise is easily generated, manifesting as a periodic, fluctuating "humming" sound, which seriously affects the user's auditory experience. This embodiment uses a fully anechoic chamber test to investigate beat frequency noise.

[0109] In practical applications, firstly, in a fully anechoic chamber environment, the compressor is controlled to operate point by point within the qualified frequency range determined in step S3, while the fan operates at its normal operating speed. At each compressor frequency point, the noise signal of the outdoor unit of the air conditioner is collected to obtain the first noise spectrum of that frequency point. Then, the sound pressure level of the noise peak appearing in the first noise spectrum is extracted and compared with the total noise value of the spectrum. If the difference between the sound pressure level of the noise peak and the total noise value is less than 10dB, it indicates that the peak contributes little to the overall noise and does not form significant beat noise, and the frequency point is deemed qualified. If the difference is greater than or equal to 10dB, it indicates that there is significant beat noise at that frequency point, which is determined to be an abnormal frequency point and requires frequency hopping shielding, that is, removing the frequency point from the available operating frequencies of the compressor.

[0110] In this embodiment, the process of troubleshooting the resonance noise between the compressor and the outdoor unit of the air conditioner includes:

[0111] The resonance noise caused by the outdoor unit compressor and the sheet metal parts of the outdoor unit during the full-frequency operation of the air conditioner was tested in a fully anechoic chamber, and the second noise spectrum at each frequency point was obtained.

[0112] The sound pressure level of the noise peak in the second noise spectrum is extracted and compared with the total noise value. If the difference between the two is less than 10dB, the frequency point is deemed qualified; otherwise, it is deemed an abnormal frequency point and the step of optimizing the sheet metal structure is executed to reduce noise radiation.

[0113] Specifically, the vibrations generated during compressor operation are transmitted through the base to the sheet metal structural components of the outdoor unit (such as the casing, partitions, and brackets). If the compressor's operating frequency is close to the natural frequency of the sheet metal components, it will cause structural resonance, amplifying the vibrations and radiating significant structural noise. This embodiment uses a fully anechoic chamber test to investigate sheet metal resonance noise.

[0114] In practical applications, firstly, in a fully anechoic chamber environment, the compressor is controlled to operate point by point within the qualified frequency range determined in step S3, and noise signals from the outdoor unit of the air conditioner are collected to obtain the second noise spectrum at each frequency point. Then, the sound pressure level of the noise peak appearing in the second noise spectrum is extracted and compared with the total noise value of the spectrum. If the difference is less than 10dB, it indicates that no obvious sheet metal resonance is caused at that frequency point, and it is judged as qualified. If the difference is greater than or equal to 10dB, it indicates that sheet metal resonance noise exists at that frequency point, and it is judged as an abnormal frequency point.

[0115] For frequencies identified as abnormal, this embodiment adopts two approaches: first, optimizing the sheet metal structure that causes resonance to reduce noise radiation at its source; second, if structural optimization is not feasible or ineffective, frequency hopping shielding is applied to the frequency point.

[0116] To address the abnormal frequency points caused by sheet metal resonance, this embodiment optimizes the sheet metal structure through a combination of one or more of the following methods:

[0117] (1) Increase the thickness of sheet metal: Increasing the thickness of sheet metal parts can improve their structural rigidity, thereby increasing their natural frequency and allowing them to avoid the excitation frequency of the compressor. At the same time, increasing the thickness also helps to reduce the vibration amplitude.

[0118] (2) Adjust the shape and quantity of sheet metal reinforcing ribs: By changing the arrangement position, direction, cross-sectional shape and quantity of reinforcing ribs, the overall stiffness and mass distribution of sheet metal parts can be adjusted, thereby changing their modal natural frequency and making them avoid the resonance zone with the excitation frequency of the compressor.

[0119] (3) Attach damping blocks to the inside of the air conditioner sheet metal structural parts: Attaching damping blocks (such as damping rubber, asphalt board, etc.) to the inside of the air conditioner sheet metal structural parts can increase the structural damping of the sheet metal parts. When the sheet metal parts vibrate, the damping material dissipates the vibration energy through internal friction, thereby reducing the vibration amplitude and noise radiation.

[0120] Through the above structural optimization measures, the frequency point that originally caused resonance may be transformed into a qualified frequency point. If significant noise problems still exist at this frequency point after optimization, frequency hopping shielding is then performed.

[0121] Based on the qualified pipeline vibration frequency points determined in step S3, and the frequency points after coupling noise investigation and sheet metal resonance noise investigation (and corresponding optimization) in step S4, the final set of usable operating frequencies for the compressor is determined. These frequency points simultaneously meet the following three conditions: qualified pipeline vibration stress, no significant beat frequency noise with the fan, and no significant resonance noise with sheet metal parts. In actual operation, the compressor operates only at these verified final operating frequency points, thereby ensuring stable and low-noise operation of the outdoor unit across the entire frequency range.

[0122] In summary, the vibration and noise control method for outdoor air conditioning units provided in this embodiment achieves comprehensive suppression of vibration and noise across the entire frequency band of the outdoor air conditioning unit through a hierarchical control strategy involving fan optimization, pipeline optimization, torque compensation, and frequency determination. Specifically, by optimizing the fan design, reducing the fan speed and rationally dividing the speed range while ensuring airflow, the aerodynamic noise and mechanical vibration of the fan are reduced at the source. The response analysis and parameter optimization of the compressor pipeline using the finite element method reduce the pipeline resonance peak value across the entire frequency band, weakening pipeline vibration along the propagation path. Pipeline vibration stress experiments identify frequency points exceeding stress limits, apply torque compensation to actively suppress vibration, and perform frequency hopping shielding on frequency points that still fail to meet standards after compensation, ensuring the reliability of the compressor pipeline operation across the entire frequency band. Finally, by investigating coupled noise and sheet metal resonance, mutual excitation amplification between the compressor, fan, and sheet metal components is avoided. This control method is not a single or passive noise reduction, but a comprehensive approach that addresses the vibration source and propagation path, from passive optimization to active control. It ensures that the vibration and noise of the outdoor unit of the air conditioner are effectively suppressed during operation across the entire frequency band, significantly improving the product's operational stability and user comfort.

[0123] Based on the above technical solution, this embodiment also proposes a vibration and noise control system for an air conditioner outdoor unit, used to implement the vibration and noise control method for the air conditioner outdoor unit as described in the embodiment. Please refer to [link / reference needed]. Figure 6 The system includes:

[0124] The fan control strategy execution module is used to execute the fan control strategy: optimize the design of the fan, reduce the fan speed while increasing the air volume, ensure that the highest speed is less than or equal to the preset speed threshold, and divide the fan speed into multiple speed levels, determining the speed value corresponding to each level based on the principle of optimal low-frequency noise.

[0125] The compressor pipeline optimization module is used to perform response analysis on the compressor pipeline using the finite element method, obtain the pipeline response curve of the compressor pipeline, and adjust the pipeline parameters based on the pipeline response curve until the number of resonance peaks in the entire frequency band of the air conditioner meets the preset conditions.

[0126] The compressor torque compensation control module is used to conduct pipeline vibration stress experiments on the optimized compressor pipeline to obtain the pipeline vibration stress value at each sweep frequency point; apply compressor torque compensation to the frequency points where the pipeline vibration stress value exceeds a preset judgment threshold, and find the optimal torque compensation control parameters; and perform frequency hopping shielding on the frequency points where the pipeline vibration stress still exceeds the preset judgment threshold under the optimal torque compensation control parameters, thereby determining the qualified frequency points of compressor pipeline vibration.

[0127] The final operating frequency determination module is used to investigate the coupling noise between the compressor and the fan and the resonance noise between the compressor and the outdoor unit of the air conditioner, based on the determined qualified frequency points of compressor pipeline vibration. It performs frequency hopping shielding on the abnormal frequency points found and / or optimizes the sheet metal structure that causes resonance, and finally determines the final operating frequency of the compressor.

[0128] It is understood that since the air conditioner outdoor unit vibration and noise control system described in this embodiment is a system for implementing the air conditioner outdoor unit vibration and noise control method described in the embodiment, the system disclosed in the embodiment is relatively simple to describe because it corresponds to the method disclosed in the embodiment. For relevant parts, please refer to the description of the method, and it will not be repeated here.

Claims

1. A method for controlling vibration noise of an air conditioner outdoor unit, characterized by, The method includes: Step S1: Execute the fan control strategy: Optimize the fan design, reduce the fan speed while increasing the air volume, ensure that the highest speed is less than or equal to the preset speed threshold, and divide the fan into multiple speed levels. Determine the speed value corresponding to each level based on the principle of optimal low-frequency noise. Step S2: Optimize the compressor piping: Use the finite element method to perform response analysis on the compressor piping, obtain the piping response curve of the compressor piping, and adjust the piping parameters based on the piping response curve until the number of resonance peaks in the entire frequency band of the air conditioner meets the preset conditions. Step S3: Perform compressor torque compensation control: Conduct a pipeline vibration stress test on the optimized compressor pipeline to obtain the pipeline vibration stress value at each sweep frequency point; apply compressor torque compensation to the frequency points where the pipeline vibration stress value exceeds the preset judgment threshold, and find the optimal torque compensation control parameters; perform frequency hopping shielding on the frequency points where the pipeline vibration stress still exceeds the preset judgment threshold under the optimal torque compensation control parameters, thereby determining the qualified frequency points of compressor pipeline vibration. Step S4: Determine the final operating frequency of the compressor: Based on the determined qualified frequency points of compressor pipeline vibration, conduct noise investigation of compressor-fan coupling and noise investigation of compressor-air conditioner outdoor unit sheet metal resonance, perform frequency hopping shielding on the abnormal frequency points found, and / or optimize the sheet metal structure that causes resonance, and finally determine the final operating frequency of the compressor.

2. The method for controlling vibration and noise of an outdoor air conditioning unit according to claim 1, characterized in that, In step S1, the optimization design of the fan includes: The fan blade installation angle is controlled to be greater than or equal to 25°; The axial projected area of ​​the axial flow fan blades is greater than 70% of the area of ​​a circular axial flow fan of the same diameter; Control the dynamic balance value of the fan blades to be less than 0.03; Modal control of the wind turbine blade structure is performed to ensure that the natural frequency of the wind turbine blade mode avoids the driving frequency of the motor power supply and its harmonics, so as to avoid resonance between the wind turbine blade and the power supply excitation.

3. The method for controlling vibration and noise of an outdoor air conditioning unit according to claim 1, characterized in that, In step S1, the preset speed threshold is 750 r / min; determining multiple fan speed levels and their corresponding speed values ​​specifically includes: The number of fan speed settings is determined to be 8; The speed ranges for each gear are set as follows: 1st gear is 350-400 r / min, 2nd gear is 400-450 r / min, 3rd gear is 450-500 r / min, 4th gear is 500-550 r / min, 5th gear is 550-600 r / min, 6th gear is 600-650 r / min, 7th gear is 650-700 r / min, and 8th gear is 700-750 r / min.

4. The method for controlling vibration and noise of an outdoor air conditioning unit according to claim 1, characterized in that, In step S2, the air conditioner's full frequency band is 6Hz-110Hz; the preset condition is that the number of resonance peaks in the full frequency band is less than 3; the adjustment of pipeline parameters includes at least one of the following: adjusting pipeline length, bending radius, and pipeline direction.

5. The method for controlling vibration and noise of an outdoor air conditioning unit according to claim 1, characterized in that, In step S3, the specific process of conducting the pipeline vibration stress test includes: Under the maximum cooling and maximum heating conditions of the air conditioner, at least one test point shall be arranged at the bend of each component of the compressor pipeline; wherein, each component includes the suction pipe, the discharge pipe, the condenser connecting pipe, and the shut-off valve connecting pipe. Frequency sweep tests were conducted at 1Hz intervals within a frequency range of 6Hz to 110Hz, and the pipeline vibration stress values ​​at each test point under each sweep frequency were output.

6. The vibration and noise control method for an outdoor air conditioning unit according to claim 5, characterized in that, In step S3, the preset judgment threshold is 12 MPa; The process of finding the optimal torque compensation control parameters includes: if the pipeline vibration stress value at each test point is greater than 12MPa at a certain frequency, then by adding a compensation current signal to the inverter control signal, and by adjusting the angle parameter of the compressor torque compensation and the current loading parameter of 10%-100%, the optimal torque compensation control parameters at that frequency point are found.

7. The method for controlling vibration and noise of an outdoor air conditioning unit according to claim 1, characterized in that, In step S4, the process of troubleshooting the coupling noise between the compressor and the fan includes: By testing the beat frequency noise caused by the compressor speed and operating frequency of the outdoor unit of the air conditioner during full-frequency operation in a fully anechoic chamber, the first noise spectrum at each frequency point was obtained. The sound pressure level of the noise peak in the first noise spectrum is extracted and compared with the total noise value. If the difference between the two is less than 10dB, the frequency point is deemed qualified; otherwise, it is deemed an abnormal frequency point and the compressor frequency point is blocked.

8. The method for controlling vibration and noise of an outdoor air conditioning unit according to claim 1 or 7, characterized in that, Step S4, the process of troubleshooting the resonance noise between the compressor and the outdoor unit of the air conditioner includes: The resonance noise caused by the outdoor unit compressor and the sheet metal parts of the outdoor unit during the full-frequency operation of the air conditioner was tested in a fully anechoic chamber, and the second noise spectrum at each frequency point was obtained. The sound pressure level of the noise peak in the second noise spectrum is extracted and compared with the total noise value. If the difference between the two is less than 10dB, the frequency point is deemed qualified; otherwise, it is deemed an abnormal frequency point and the step of optimizing the sheet metal structure is executed to reduce noise radiation.

9. The method for controlling vibration and noise of an outdoor air conditioning unit according to claim 8, characterized in that, The optimization of the sheet metal structure that causes resonance includes one or more of the following methods: increasing the sheet metal wall thickness, adjusting the shape and number of sheet metal reinforcing ribs, and attaching damping blocks to the inside of the air conditioning sheet metal structural components.

10. A vibration and noise control system for an air conditioner outdoor unit, used to implement the vibration and noise control method for an air conditioner outdoor unit as described in any one of claims 1 to 9, characterized in that, The system includes: The fan control strategy execution module is used to execute the fan control strategy: optimize the design of the fan, reduce the fan speed while increasing the air volume, ensure that the highest speed is less than or equal to the preset speed threshold, and divide the fan speed into multiple speed levels, determining the speed value corresponding to each level based on the principle of optimal low-frequency noise. The compressor pipeline optimization module is used to perform response analysis on the compressor pipeline using the finite element method, obtain the pipeline response curve of the compressor pipeline, and adjust the pipeline parameters based on the pipeline response curve until the number of resonance peaks in the entire frequency band of the air conditioner meets the preset conditions. The compressor torque compensation control module is used to conduct pipeline vibration stress experiments on the optimized compressor pipeline to obtain the pipeline vibration stress value at each sweep frequency point; apply compressor torque compensation to the frequency points where the pipeline vibration stress value exceeds a preset judgment threshold, and find the optimal torque compensation control parameters; and perform frequency hopping shielding on the frequency points where the pipeline vibration stress still exceeds the preset judgment threshold under the optimal torque compensation control parameters, thereby determining the qualified frequency points of compressor pipeline vibration. The final operating frequency determination module is used to investigate the coupling noise between the compressor and the fan and the resonance noise between the compressor and the outdoor unit of the air conditioner, based on the determined qualified frequency points of compressor pipeline vibration. It performs frequency hopping shielding on the abnormal frequency points found and / or optimizes the sheet metal structure that causes resonance, and finally determines the final operating frequency of the compressor.

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