A noise reduction control method, air conditioning unit, rail vehicle and noise reduction device

Abstract

The application provides a noise reduction control method, an air conditioning unit, a railway vehicle and a noise reduction device, the air conditioning unit comprising a noise reduction device, a control system built in the noise reduction device, the noise reduction device comprising one or more sound collection devices capable of collecting noise data, the control system having a standard value of running noise built in, the control system comparing the real-time noise data collected by the collection device with the standard value of noise, obtaining noise exceeding the limit, and eliminating the noise exceeding the limit according to a predetermined procedure. The application further provides the air conditioning unit, the railway vehicle and the noise reduction device using the noise reduction control method. The noise reduction control method, the air conditioning unit, the railway vehicle and the noise reduction device can effectively reduce the running noise of the air conditioning system itself and intelligently reduce the noise of the railway vehicle.

Description

Technical Field

[0001] This invention relates to the field of air conditioning product technology, and in particular to a noise reduction control method, an air conditioning unit, a rail vehicle, and a noise reduction device. Background Technology

[0002] Variable frequency air conditioners adjust the output cooling capacity by automatically adjusting the compressor operating frequency and fan speed according to load changes such as the indoor set temperature target and passenger volume, so as to keep the indoor temperature within the set temperature range. When the indoor temperature reaches the desired value, the air conditioner compressor maintains a certain speed, and the fan adjusts the air volume and speed by adjusting the speed (that is, the speed of rotor components such as fan and compressor is changing). Therefore, the noise level and sound spectrum emitted by the air conditioner itself are changing. Due to the complex environment of the vehicle's operating route, the noise in the carriage is also changing.

[0003] Currently, active noise reduction measures for rail vehicle systems are generally integrated inside the vehicle's air ducts or carriages. However, due to limitations in the installation location and number of sound sensors and noise generators in active noise reduction systems, it is impossible to monitor the noise status of the variable frequency air conditioning unit and the rotor components inside the unit in real time. This makes it impossible to simultaneously reduce the impact of the air conditioning's operating noise and environmental noise on the carriage interior, thus affecting the ride comfort of the vehicle. Summary of the Invention

[0004] The main objective of this invention is to address the aforementioned problems and shortcomings by providing a noise reduction control method, an air conditioning unit, a rail vehicle, and a noise reduction device that can effectively reduce noise.

[0005] To achieve the above objectives, the present invention first provides a noise reduction control method, the technical solution of which is:

[0006] A noise reduction control method is provided, comprising a control system built into a noise reduction device. The noise reduction device includes one or more sound acquisition devices capable of acquiring noise data. The control system has a built-in standard value for operating noise. The control system compares the real-time noise data acquired by the acquisition devices with the standard value of noise to obtain the noise exceeding the limit, and eliminates the noise exceeding the limit according to a predetermined program.

[0007] Furthermore, the noise reduction device includes a sound source device installed at the noise collection point, and the control system controls the sound source device at the point where the noise exceeds the limit to emit an anti-phase sound source to reduce the noise.

[0008] Furthermore, octave band analysis is performed on the excessive noise to identify the excessive sound sources within it. These excessive sound sources are then eliminated, thereby reducing the total sound pressure level of the excessive noise.

[0009] Furthermore, the following steps are used to identify the source of the excessive noise.

[0010] S1, perform octave band analysis on the excessive noise signal Lp collected by the sound acquisition device to obtain f and P corresponding to Lp(f,P) of the noise. Calculate the difference between adjacent frequency bands for each noise frequency band, where Δ... 左 =|P i-1 -P i | and Δ 右 =|P i+1 -P i |, when Δ 左 or Δ 右 When the value exceeds the limit, it is marked as Lp(f) i1 ,P i1 ), ..., Lp(f ij ,P ij ), ..., Lp(f in ,P in ), where f represents frequency, P represents amplitude; i, j, n are natural numbers;

[0011] S2, calculate Δ P =|MAX(P i1 ,L,P ij ,LP in )-P ij When Δp is greater than a predetermined value, it is discarded to obtain the final over-limit sound source Lp(F0, P), where F0 is the frequency of the over-limit sound source.

[0012] Furthermore, Δ 左 or Δ 右 There are multiple limits, which are marked separately.

[0013] Furthermore, the limits include N1, N2, and N3, dividing the difference between adjacent frequency bands into three levels.

[0014] When Δ 左 or Δ 右 When N is greater than N1, label LpH(f) i1 ,P i1 ), ..., LpH(f ij ,P ij ),…,LpH(f in ,P in );

[0015] When Δ 左 or Δ 右 When N2 is greater than or equal to N1, mark LpM(f) i1 ,P i1 ), ..., LpM(f ij ,P ij ),…..,LpM(f in ,P in );

[0016] When Δ 左 or Δ 右 When N3 is greater than or equal to N2, mark LpL(f) i1 ,P i1 ), ..., LpL(f ij ,P ij ),…..,LpL(f in ,P in );

[0017] When Δ 左 or Δ 右 When the value is greater than 0 dB and less than or equal to N3, mark Lp(f) i1 ,P i1 ), ..., Lp(f ij ,P ij ),…..,Lp(f in ,P in );

[0018] In step S2, the three levels of over-limit sound sources and their corresponding sound source frequencies Lp(F0, P) are obtained.

[0019] Furthermore, noise reduction processing is performed on all acquired out-of-limit frequencies.

[0020] Furthermore, the noise collected by the sound acquisition device is analyzed in one-third octave band within the range of 50Hz to 20000Hz to obtain the frequency and amplitude of the noise, where 50 < (i, j, n) < 20000.

[0021] The second objective of this invention is to provide an air conditioning unit, which adopts the following technical solution:

[0022] An air conditioning unit that controls noise using the method described above.

[0023] The third objective of this invention is to provide a rail vehicle, employing the following technical solution:

[0024] A rail vehicle that employs the method described above to reduce operating noise generated by an air conditioning unit.

[0025] The fourth objective of this invention is to provide a noise reduction device, which adopts the following technical solution:

[0026] A noise reduction device includes a control system, one or more sound acquisition devices capable of acquiring noise data, and a sound source device. The control system incorporates the noise reduction control method described above to eliminate excessive noise.

[0027] In summary, the noise reduction control method, air conditioning unit, rail vehicle, and noise reduction device provided by this invention have the following advantages compared with the prior art:

[0028] 1. By acquiring the air conditioner's output noise characteristics in advance, the system can simultaneously control and process internal noise reduction and external active noise, thus saving energy.

[0029] 2. Real-time monitoring of air conditioner noise and detection of its health status, providing a more intuitive understanding;

[0030] 3. An early warning system can be activated to alert staff if the air conditioner outputs abnormal noise, prompting them to request maintenance.

[0031] 4. When the noise level inside the vehicle exceeds the standard, the system will intelligently activate noise reduction measures to improve vehicle ride comfort and reduce noise reduction costs.

[0032] 5. An early warning system can be activated to alert staff when abnormal noise levels persist inside the vehicle, prompting them to request maintenance.

[0033] 6. With air conditioners becoming increasingly intelligent, this technology can effectively reduce or eliminate the need for regular checks on air conditioner noise, providing a more comfortable riding environment while saving on manual inspections, reducing labor costs, and improving safety and reliability. Attached image description:

[0034] Figure 1 This invention provides a schematic diagram of the outdoor cavity structure of an air conditioning unit in a rail vehicle.

[0035] Figure 2 This invention provides a schematic diagram of a rail vehicle structure;

[0036] Figure 3 This invention provides a noise reduction logic diagram for an air conditioning unit;

[0037] Figure 4 This invention provides a logic diagram for intelligent noise reduction in rail vehicles.

[0038] Figure 5: Schematic diagram of identifying excessive sound sources in the noise reduction control method provided by the present invention;

[0039] Figure 6 This invention provides a logic diagram for monitoring and alarming the noise status of rail vehicles.

[0040] Among them, the air conditioning unit 1, outdoor cavity 2, evaporator 3, static pressure cavity 4, in-vehicle air duct 5, passenger compartment 6, first sound acquisition device 7, first sound source device 8, second sound acquisition device 9, and second sound source device 10 are included. Detailed Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0042] This invention first provides a noise reduction control method, a control system built into a noise reduction device, the noise reduction device including one or more sound acquisition devices capable of collecting noise data, the control system having a built-in standard value for operating noise, the control system comparing the real-time noise data collected by the acquisition devices with the standard value of noise, obtaining the noise exceeding the limit, and eliminating the noise exceeding the limit according to a predetermined program.

[0043] Taking an air conditioning unit for rail vehicles as an example, this invention provides a noise reduction control method. In this invention, as... Figure 1 and Figure 2 As shown, the air conditioning unit 1 of the rail vehicle includes an indoor cavity and an outdoor cavity 2. The outdoor cavity 2 is located on the top of the passenger compartment 6, with an evaporator 3 inside and a static pressure cavity 4 at the end. After the fresh air from the outside environment (outdoors) and the return air in the passenger compartment 6 are mixed, they are heat exchanged through the evaporator 3 and filtered through the filter screen. Under the action of the fan, they flow at high speed into the static pressure cavity 4. The operating noise of the air conditioning unit 1 flows into the static pressure cavity 4 at the same time as the high-speed airflow after the temperature change. After a stable airflow is formed in the static pressure cavity 4, it enters the passenger compartment 6 through the in-vehicle air duct 8.

[0044] To prevent the operating noise of the air conditioning unit 1 from entering the passenger compartment 6 with the airflow, an active noise reduction device is installed in the static pressure chamber 4. In this embodiment, the active noise reduction device mainly includes a first sound source device 8, which can emit a sound source with a frequency out of phase with the noise in the static pressure chamber 4 to cancel the frequency of the noise and achieve the purpose of noise elimination. Before the air conditioning unit 1 is installed, the noise level in the static pressure chamber 4 is tested and collected at different frequencies. After collecting a large amount of data, the data is analyzed to determine the correspondence between different operating frequencies of the air conditioning unit 1 and the noise in the static pressure chamber 1, and the data is pre-stored in the controller of the air conditioning unit 1. Furthermore, during data collection, the correspondence between the air conditioning operating frequency, the rail vehicle operating status, and the noise in the static pressure chamber 4 can also be collected and pre-stored in the controller. After the variable frequency air conditioning system is assembled on the rail vehicle, in operation, the outdoor fresh air and the return air from the passenger compartment 6 are mixed, heat exchanged, and filtered before being sent by the fan to the static pressure chamber 4 at the end of the outdoor cavity 2. The wind noise and the noise generated by the operation of the air conditioning unit 1 itself enter the static pressure chamber 4 along with the high-speed airflow. The controller controls the air conditioning unit 1 to operate at different frequencies according to the temperature control requirements to effectively control the temperature in the passenger compartment 6. At the same time, the controller predicts the noise value in the static pressure chamber 4 at this time based on the stored relationship between the operating frequency and the noise, and controls the first sound source device 8 to emit a sound source that is out of phase with the noise in a directional manner to eliminate the noise and achieve active noise reduction inside the air conditioning unit 1. The stable and noiseless airflow output from the static pressure chamber 1 enters the passenger compartment 6 through the in-vehicle air duct 5, improving the comfort of the passenger compartment.

[0045] Under the condition that the temperature control requirements of passenger compartment 6 remain unchanged and the external ambient temperature is relatively stable, the air conditioning unit 1 will operate at a stable frequency within a certain time range. However, the noise in the static pressure chamber 4 may change with the operation of the rail vehicle. To further achieve effective active noise reduction of the air conditioning unit 1, a first sound acquisition device 7 is also installed in the static pressure chamber 4 to periodically collect real-time noise values ​​or noise data in the static pressure chamber 4. The controller adjusts and controls the first sound source device 8 to emit a directionally opposite-phase sound source signal based on the real-time noise data, thereby achieving active noise reduction. The controller has a built-in timer to determine the working time T of the stable operating frequency of the air conditioning unit 1. When the working time T is greater than the predetermined time, the controller controls the first sound acquisition device 7 to enter the working state, and as described above, adjusts and controls the frequency of the opposite-phase sound source emitted by the first sound source device 8 according to the real-time noise data in the static pressure chamber 4, thereby achieving active noise reduction in the static pressure chamber 4. Passive noise reduction devices can also be installed in the static pressure chamber 4, such as laying sound-absorbing cotton on the inner wall of the static pressure chamber 4 to eliminate some of the noise.

[0046] Airflow enters the vehicle's air duct 5 from the static pressure chamber 4. During its movement within the air duct 5 and its entry into the passenger compartment 6 from the air vents, new noise may be generated. To eliminate this noise, a second sound acquisition device 9 is installed in the air duct 5 to collect noise data. Furthermore, the second sound acquisition device 9 can be installed on the bottom wall of the air duct 5 (the side wall parallel to / close to the passenger compartment 6), especially at the air vents, to collect noise data at the air vents. A second sound source device 10 is installed in the passenger compartment 6 to emit anti-phase sound sources targeting the wind noise at each air vent, thus eliminating the airflow noise. Correspondingly, both the second sound acquisition device 9 and the second sound source device 10 are connected to a controller. The controller receives the noise data collected by the second sound acquisition device 9 and thereby controls the second sound source device 10 to emit anti-phase sound sources of corresponding frequencies to eliminate the airflow noise, achieving active noise reduction outside the air conditioning system. Alternatively, the second sound acquisition device 9 can be installed inside the guest room 6, for example, at each air vent in the guest room 6, to detect the noise data at the air vent. Based on the noise data, the controller controls the second sound source device 10 to emit an anti-phase sound source.

[0047] In this embodiment, the first and second sound source devices are microphones, and the controller controls the emission of sound sources of different frequencies. The emission direction of the sound source is opposite to the phase of the noise. When two sound waves with the same frequency but opposite wave directions (phases) meet, the sound waves are balanced out of each other, thus achieving the effect of noise cancellation.

[0048] It should be noted that, based on big data analysis of the air conditioning system test, the first / second sound acquisition device and the first / second sound source device determine one or more locations with high noise levels in the static pressure chamber 4 and the vehicle air duct 5, and determine the direction of the noise, so as to determine the location of the first / second sound acquisition device and the first / second sound source device, in order to accurately measure the noise, and to directionally emit a sound source in opposite phase.

[0049] In this embodiment, a first sound acquisition device 7 and a first sound source device 8 are simultaneously installed in the static pressure chamber 4. First, the controller controls the first sound source device 8 to emit a sound source opposite to the noise based on the real-time operating frequency of the air conditioning unit 1 and the relationship between operating frequency and noise from previous big data analysis, so as to achieve active noise reduction. After the air conditioning unit 1 stabilizes at a constant operating frequency, the controller then adjusts the frequency of the anti-phase sound source emitted by the first sound source device 8 periodically based on the noise data from the first acquisition device 7. In practical applications, if a large amount of test big data collection and processing has not been carried out in the early stage, and the relationship between operating frequency and noise has not been pre-stored, the matching control of the first sound acquisition device 7 and the first sound source device 8 can be directly adopted. After the air conditioning unit 1 is running, the first sound acquisition device 7 collects the noise data in the static pressure chamber 4 in real time, and the controller controls the first sound source device 8 to emit a directional sound source with the same frequency as the noise data and opposite phase based on the received noise data; or, the controller can control the first sound source device 8 to emit a directional sound source with the same frequency as the noise data and opposite phase based on the relationship between operating frequency and noise pre-stored in the controller. In practical applications, a corresponding noise reduction device can be installed at any location in the air conditioning unit 1 where operating noise can be generated. The operating noise generated at this location is collected by a sound acquisition device, and a corresponding frequency anti-phase sound source is emitted by a sound source device to reduce the operating noise generated at this location.

[0050] When noise control is applied to air conditioning unit 1, such as Figure 3As shown, the sound acquisition devices at each frequency point (the location where noise can be generated, i.e., the noise signal acquisition point) of air conditioning unit 1 collect noise under all operating states (each frequency point) of air conditioning unit 1, perform octave band analysis, and extract sound source characteristics; at the same time, the noise at all operating frequencies at each possible location point of the fan, compressor, air duct, etc., is tested, and octave band analysis is performed to extract sound source characteristics; by comparing the sound source characteristics of the sound acquisition devices with the sound source characteristics of each fan and compressor, the frequency components and contribution of each noise source of the sound acquisition devices are determined, and finally the noise characteristics corresponding to each operating state of the air conditioner are obtained. Air conditioning unit 1 determines a standard noise level, i.e., a noise reduction benchmark value, according to noise requirements, and pre-stores it in the controller. The noise reduction devices installed at various locations of air conditioning unit 1 reduce the operating noise of the air conditioning unit to or below the standard noise level. The controller can set a uniform standard noise level for air conditioning unit 1, or it can set standard noise levels separately at the locations where operating noise is generated, or set standard noise levels different from other parts at some noise locations.

[0051] The controller of air conditioning unit 1 receives real-time noise information collected by various sound acquisition devices. The controller pre-stores standard noise levels, which can be a unified standard noise level after big data simulation, or a standard noise level corresponding to different operating conditions of air conditioning unit 1. Based on the difference between the real-time noise and the standard noise, the controller controls the corresponding sound source device to emit a corresponding anti-phase sound source, reducing the noise at this location to the standard noise level or below. In this embodiment, by identifying the excessive sound source, the excessive sound source is purposefully eliminated to the standard noise level or below, while simultaneously improving the sound quality. The system analysis and calculation for identifying the excessive sound source includes the following steps:

[0052] S1: The noise signals Lp collected by the sound acquisition devices at each acquisition point inside the carriage are analyzed using octave band analysis to obtain Lp(f,P). In this embodiment, one-third octave band analysis is performed on the noise in the range of 50Hz to 20000Hz to obtain the corresponding f and P, forming the noise map shown in Figure 5. The difference between adjacent frequency bands is calculated for each obtained noise frequency band: Δ 左 =|P i-1 -P i | and Δ 右 =|P i+1 -P i |, when Δ 左 or Δ 右 When the value exceeds the limit, it is marked as L. p (f i1 ,P i1 ), ..., L p (f ij ,P ij ), ..., L p (f in ,P in), where f represents frequency, P represents amplitude; i, j, n are natural numbers;

[0053] In this embodiment, Δ 左 or Δ 右 The limit can be set to different values ​​according to the noise reduction needs, so as to achieve different levels of noise reduction effect. For example, the limit can be set to N1, N2, and N3, dividing the adjacent frequency band into three levels to achieve three levels of noise reduction.

[0054] When Δ 左 or Δ 右 When N is greater than N1, label LpH(f) i1 ,P i1 ), ..., LpH(f ij ,P ij ),…,LpH(f in ,P in );

[0055] When Δ 左 or Δ 右 When N2 is greater than or equal to N1, mark LpM(f) i1 ,P i1 ), ..., LpM(f ij ,P ij ),…..,LpM(f in ,P in );

[0056] When Δ 左 or Δ 右 When N3 is greater than or equal to N2, mark LpL(f) i1 ,P i1 ), ..., LpL(f ij ,P ij ),…..,LpL(f in ,P in );

[0057] When Δ 左 or Δ 右 When the value is greater than 0 dB and less than or equal to N3, mark Lp(f) i1 ,P i1 ), ..., Lp(f ij ,P ij ),…..,Lp(f in ,P in );

[0058] In this embodiment, N1 = 7, N2 = 5, and N3 = 3, and the noise reduction is divided into three levels:

[0059] When Δ 左 or Δ 右 When it is greater than 7dB, label LpH(f)i1 ,P i1 ), ..., LpH(f ij ,P ij ),…..,LpH(f in ,P in );

[0060] When Δ 左 or Δ 右 When the value is greater than 5dB and less than or equal to 7dB, mark LpM(f) i1 ,P i1 ), ..., LpM(f ij ,P ij ),…..,LpM(f in ,P in );

[0061] When Δ 左 or Δ 右 When the value is greater than 3dB and less than or equal to 5dB, mark LpL(f) i1 ,P i1 ), ..., LpL(f ij ,P ij ),…..,LpL(f in ,P in );

[0062] When Δ 左 or Δ 右 When the value is greater than 0 dB and less than or equal to 3 dB, mark Lp(f) i1 ,P i1 ), ..., Lp(f ij ,P ij ),…..,Lp(f in ,P in ).

[0063] Where f represents frequency, P represents amplitude, and 50 < (i,j,n) < 20000.

[0064] S2, Calculate:

[0065] Δ P =|MAX(P i1 ,L,P ij ,LP in )-P ij |

[0066] Extract all f values ​​with Δp > 10dB from Lp7, Lp5, and Lp3 using the above formula. ij And remove them respectively in the first step of marking. Obtain the final Lp over-limit (F0, P) for high, medium and low levels. Where F0 is the over-limit sound source frequency.

[0067] The preceding text used only three noise levels as an example to introduce how to identify excessive noise and determine the specific boundary data for each level. In practical applications, the noise level and the data for each level can be reasonably set according to different environmental noise requirements.

[0068] The total sound pressure level of noise is collected by a sound acquisition device. A one-third octave band analysis is then performed on this noise to obtain its frequency band. The Y-axis represents the sound pressure value at different frequencies within the noise frequency band. The total sound pressure level of the noise can be calculated using the one-third octave band analysis. In the frequency band diagram, prominent frequency bands will increase the total sound pressure level. Therefore, to reduce noise, it is necessary to find and identify the frequency bands that cause the increased total sound pressure level. These frequency bands can be identified as the out-of-limit sound source frequencies, and targeted noise reduction processing can be performed on these out-of-limit sound source frequencies. By reducing the sound pressure value of the frequency band corresponding to the out-of-limit sound source frequencies, the overall sound pressure level is reduced, achieving the noise reduction effect. In this embodiment, the operating noise of five fans is collected, and a one-third octave band analysis is performed on the collected noise, resulting in the noise level shown in Figure 5. Figures 5-1 to 5-5 The five noise frequency band diagrams shown are used to calculate the total sound pressure level of the noise corresponding to each diagram. The values ​​are 56.55 dB(A), 58.03 dB(A), 57.49 dB(A), 58.79 dB(A), and 58.71 dB(A), respectively. All of these exceed the set standard value of 55 dB(A). According to theoretical requirements, noise reduction processing is needed for the operating noise of each fan.

[0069] As shown in Figure 5, Figure 5-1 The Y-axis represents the sound pressure level of the noise frequency band in the sampling area. The lines connecting each frequency band form a relatively smooth curve. The lines connecting most frequency bands to the left and right frequency bands are relatively smooth. As mentioned earlier, the Δ between each frequency band can be calculated. 左 and / or Δ 右 Determine the interval range of each difference: (7, ∝), (5, 7), (3, 5), (0, 3). Then calculate Δp and extract f values ​​where Δp > 10dB. ij After elimination, only four out-of-limit sound source frequencies are obtained, as shown in the figure, which are marked by numbers as four frequency bands. These are marked as out-of-limit sound sources, and noise reduction can be performed on these four frequency bands to reduce the noise (amplitude). For example, the sound pressure of the out-of-limit sound source can be directly reduced to Δleft or Δright of the original frequency band, so that the reduced frequency band and the calculated Δleft or Δright of the adjacent frequency band are within the allowable range. This makes the frequency band corresponding to the out-of-limit sound source similar to its left or right adjacent frequency band, so as not to form abrupt frequencies. Thus, while reducing the overall noise value, the sound quality of the noise is improved. Figure 5-3 The situation is similar.

[0070] right Figures 5-2 to 5-5The noise shown is processed in the same way. By calculating Δleft and / or Δright of adjacent frequency bands (sound pressure values), the range of each difference is determined. (7, ∝), (5, 7), (3, 5), (0, 3) are marked respectively. Δp is calculated, and f values ​​with Δp > 10dB are extracted. ij After elimination, the frequencies of the out-of-limit sound sources are finally obtained. As shown in the figure, the frequency bands marked by numbers are marked as out-of-limit sound sources, and targeted noise reduction processing is carried out. Through the sound source device, an anti-phase sound source is emitted to reduce the sound pressure value of the out-of-limit sound source, thereby reducing noise.

[0071] It should be noted that in this embodiment, noise is reduced specifically for the excessive noise source by emitting an anti-phase sound source, but not all the noise at this sampling point is reduced to zero. Instead, by identifying the excessive noise source, the abrupt frequency band is reduced to an amplitude similar to other frequency bands, so that the operating noise is relatively smooth and there are no sharp sound frequencies. The sound quality of the noise is improved on the basis of reducing the overall noise amplitude.

[0072] By employing the two-step method described above to identify out-of-limit sound sources and frequencies, we can first search for frequency bands and frequencies with excessively large differences between adjacent frequency bands, i.e., frequency bands that affect the overall noise sound pressure level and sound quality. Secondly, by comparing the differences in amplitude corresponding to octaves, we mark the frequency bands with larger differences, i.e., selecting the frequencies that have the greatest impact on noise levels. The out-of-limit sound source frequencies identified in this way have the greatest impact on sound quality and sound pressure level. Using these out-of-limit frequencies for noise reduction can both accurately reduce noise and improve sound quality.

[0073] In addition, the difference between adjacent frequency bands is divided into three levels: high, medium and low. This means that the impact of the sound quality of the sound source exceeding the limit is also divided into three levels. This can be used to determine the target frequency of intelligent noise reduction and sound quality improvement.

[0074] As described above, noise reduction control is applied to air conditioning unit 1. When air conditioning unit 1 is installed on a railcar, the noise reduction control method is also applicable to the intelligent noise reduction control of the entire carriage (including the noise generated by train operation and the operating noise of air conditioning unit 1). In addition to the noise reduction devices arranged in air conditioning unit 1, corresponding noise reduction devices can also be installed in the carriage to reduce the noise inside the carriage, realize real-time monitoring of the inside of the carriage (including the operating noise of air conditioning unit 1 in the carriage), and automatically activate the active noise reduction device (a sound source device that can emit an anti-phase sound source) when the collected ground noise signal exceeds the standard noise inside the carriage, thereby achieving intelligent noise reduction. Figure 4As shown, air conditioning unit 1 obtains the output signal Lp from the in-car noise acquisition device through the controller. The control system compares the real-time acquired noise value Lp with the indoor noise requirement value L (standard noise). If Lp ≤ L, it returns and re-detects the in-car noise after a 10-second interval (the interval can be set as needed, and after the predetermined interval), and returns the value. If Lp > L, the derivation logic proceeds to the next step, detecting the duration of Lp exceeding the noise requirement. When the duration > T (this duration can also be set by the user, such as 10 seconds, the same below), it proceeds to the next step, analyzing the characteristics of the in-car noise (using...). Figure 3 The method shown is used to further determine the frequency F0 of the excessive sound source. When the duration is less than or equal to T, the system enters the continuous detection count. If the number of consecutive detections is greater than n (the number of consecutive detections can be set by the user, such as 10 times, the same below), the system proceeds to the next step. If the number of consecutive detections is not greater than n, the system returns to re-detect the noise inside the vehicle, provides feedback values, and repeats the detection for comparison. After analyzing the noise characteristics collected inside the vehicle and determining the frequency F0 of the excessive sound source, the system selectively or simultaneously activates the active noise reduction devices in the air conditioning and the vehicle based on the analyzed frequency components of the excessive sound source. In practical applications, the interval for detecting noise inside the vehicle and the number of consecutive detections can be set according to the required accuracy of noise control. When intelligent noise reduction is performed simultaneously on the operating noise inside the rail vehicle and the operating noise of the air conditioning unit, the noise information collected by each sound acquisition device can be transmitted to the controller of the air conditioning unit or the main controller of the rail vehicle according to a predetermined program. Sound acquisition devices and corresponding sound source devices are set at each noise generation location of the air conditioning unit and the rail vehicle. The controller or main controller pre-stores the corresponding noise standard value for each point and compares the collected real-time noise with the corresponding pre-stored standard value. The controller or main controller controls each point to perform intelligent noise reduction.

[0075] In the embodiments provided by this invention, while enabling real-time monitoring and intelligent noise reduction within the carriage, an abnormal status alarm signal can also be fed back when the number of consecutive noise detections exceeds a certain limit. For example... Figure 6 As shown, the air conditioning unit 1 obtains the output signal Lp from the in-cabin sound acquisition device through its internal controller. The controller compares the real-time noise value Lp with the standard indoor noise value L. If Lp ≤ L, it returns to the previous state and re-detects the in-cabin noise, providing a new value. If Lp > the required value L, it proceeds to the next step and activates the intelligent noise reduction module.

[0076] Set a continuous detection time to confirm whether the noise level inside the carriage exceeds the limit for an extended period of time (t). For example, if t = 90 minutes, and the noise level inside the carriage exceeds the required value of 90 minutes (the duration can be set by the user), the system will count the number of times the noise level exceeds the limit. Each time the noise level exceeds 90 minutes, the count will increase by 1, and the noise level exceeding the limit will be detected again. If this step is repeated 5 times or more, the air conditioning controller will send an alarm signal to the air conditioning operation and maintenance system.

[0077] When rail vehicles can also trigger noise exceeding limits, and when both the rail vehicle and its installed air conditioning unit trigger such alarms simultaneously, the controller or main controller can issue the alarm and transmit the data to either the air conditioning maintenance system or the rail vehicle maintenance system, depending on the location of the exceeding noise level. Alternatively, the data can be transmitted uniformly to either system. The controller or main controller can also have a built-in alarm system that can trigger alarms at specific noise exceeding locations, allowing the maintenance system to perform targeted maintenance.

[0078] Here, taking a rail vehicle air conditioner as an example, we introduce an intelligent noise reduction control method for air conditioning. In practical applications, the air conditioning unit 1 can be used in various environments requiring temperature regulation, such as workshops and office buildings. This should not be construed as a limitation of the present invention. Similarly, the noise exceeding the limit sound source, the exceeding the limit sound source frequency, and the noise reduction method provided by the present invention can also be applied to various technical fields that generate noise and require noise reduction. The methods described above can also be integrated into the control system of the noise reduction device to perform noise reduction control within the range controlled by the device. The noise reduction device includes one or more sound acquisition devices and sound source devices capable of collecting noise data from different locations. Based on the methods described above, noise reduction control, noise exceeding the limit alarm, and other operations are performed.

[0079] In summary, the noise reduction control method, air conditioning unit, rail vehicle, and noise reduction device provided by this invention have the following advantages compared with the prior art:

[0080] 1. By acquiring the air conditioner's output noise characteristics in advance, the system can simultaneously control and process internal noise reduction and external active noise, thus saving energy.

[0081] 2. Real-time monitoring of air conditioner noise and detection of its health status, providing a more intuitive understanding;

[0082] 3. An early warning system can be activated to alert staff if the air conditioner outputs abnormal noise, prompting them to request maintenance.

[0083] 4. When the noise level inside the vehicle exceeds the standard, the system will intelligently activate noise reduction measures to improve vehicle ride comfort and reduce noise reduction costs.

[0084] 5. An early warning system can be activated to alert staff when abnormal noise levels persist inside the vehicle, prompting them to request maintenance.

[0085] 6. With air conditioners becoming increasingly intelligent, this technology can effectively reduce or eliminate the need for regular checks on air conditioner noise, providing a more comfortable riding environment while saving on manual inspections, reducing labor costs, and improving safety and reliability.

[0086] As described above, similar technical solutions can be derived from the given solutions. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this invention, without departing from the scope of the present invention, shall still fall within the scope of the present invention.

Claims

1. A noise reduction control method, characterized in that: A control system built into a noise reduction device, wherein the noise reduction device includes one or more sound acquisition devices capable of acquiring noise data, the control system has a built-in standard value for operating noise, the control system compares the real-time noise data acquired by the acquisition devices with the standard value of noise, obtains the noise exceeding the limit, and eliminates the noise exceeding the limit according to a predetermined program; Octave band analysis is performed on the excessive noise to identify the excessive sound sources in the excessive noise, and the excessive sound sources are eliminated to reduce the total sound pressure of the excessive noise. The following steps are used to identify the source of the excessive noise. S1, perform octave band analysis on the excessive noise signal Lp collected by the sound acquisition device to obtain f and P corresponding to Lp(f,P) of the noise. Calculate the difference between adjacent frequency bands for each noise frequency band, where Δ... 左 =|P i-1 -P i | and Δ 右 =|P i+1 -P i |, when Δ 左 or Δ 右 When the value exceeds the limit, it is marked as L. p (f i1 ,P i1 ), ..., L p (f ij ,P ij ), ..., L p (f in ,P in ), where f represents frequency and P represents amplitude; i, j, n are natural numbers; S2, calculate Δ P =|MAX(P i1 ,…,P ij ,…P in )-P ij When Δp is greater than a predetermined value, it is discarded to obtain the final over-limit sound source Lp(F0, P), where F0 is the frequency of the over-limit sound source.

2. The noise reduction control method as described in claim 1, characterized in that: The noise reduction device includes a sound source device installed at the noise collection point, and the control system controls the sound source device at the point where the noise exceeds the limit to emit an anti-phase sound source to reduce the noise.

3. The noise reduction control method as described in claim 1, characterized in that... :Δ 左 or Δ 右 There are multiple limits, which are marked separately.

4. The noise reduction control method as described in claim 3, characterized in that: The limits include N1, N2, and N3, which divide the difference between adjacent frequency bands into three levels. When... When Δ 左 or Δ 右 When N is greater than N1, label LpH(f) i1 ,P i1 ), ..., LpH(f ij ,P ij ),…,LpH(f in ,P in ); When Δ 左 or Δ 右 When N2 is greater than or equal to N1, mark LpM(f) i1 ,P i1 ), ..., LpM(f ij ,P ij ),…..,LpM(f in ,P in ); When Δ 左 or Δ 右 When N3 is greater than or equal to N2, mark LpL(f) i1 ,P i1 ), ..., LpL(f ij ,P ij ),…..,LpL(f in ,P in ); When Δ 左 or Δ 右 When the value is greater than 0 dB and less than or equal to N3, mark Lp(f) i1 ,P i1 ), ..., Lp(f ij ,P ij ),…..,Lp(f in ,P in ); In step S2, the three levels of over-limit sound sources and their corresponding sound source frequencies Lp(F0, P) are obtained.

5. The noise reduction control method as described in claim 4, characterized in that: Noise reduction processing is performed on all acquired out-of-limit frequencies.

6. The noise reduction control method as described in claim 1, characterized in that: The noise collected by the sound acquisition device is analyzed within one-third octave band in the range of 50Hz to 20000Hz to obtain the frequency and amplitude of the noise, where 50 < (i, j, n). <20000.

7. An air conditioning unit, characterized in that: The air conditioning unit controls noise by means of the method described in any one of claims 1 to 6.

8. A rail vehicle, characterized in that: The rail vehicle employs the method described in any one of claims 1 to 6 to reduce the operating noise generated by the air conditioning unit.

9. A noise reduction device, characterized in that: The noise reduction device includes a control system, one or more sound acquisition devices and sound source devices capable of acquiring noise data, wherein the control system incorporates the noise reduction control method as described in any one of claims 1 to 6 to eliminate excessive noise.

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