Automobile active noise reduction method and system

Abstract

The invention relates to the technical field of noise and vibration control, and discloses an automobile active noise reduction method and system which comprises a first vibration sensor installed near an engine of a commercial vehicle and a second vibration sensor installed near a trunk of the commercial vehicle. The two vibration sensors are respectively connected to the ANC controller; acquiring and judging environmental parameters of the vehicle and the running state of an engine in real time, and selecting a corresponding vibration sensor to acquire a vibration signal of the engine according to a judgment condition; the rotating speed information of the current engine is calculated according to the vibration signal and the engine parameters; and the rotating speed information is input into the first ANC controller, and noise reduction information is output by the first ANC controller. According to the invention, a plurality of acquisition points are effectively arranged and are flexibly switched, so that the signal acquisition stability is ensured, the rotating speed precision is improved, the signal delay is obviously reduced, high-precision noise reduction is realized, and the ANC algorithm performance is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of noise and vibration control, and particularly to a method and system for active noise reduction in automobiles. Background Art

[0002] With the rapid development of the automotive industry, consumers' requirements for vehicle comfort and driving experience are increasing day by day. Noise pollution has become one of the important factors affecting driving comfort. Especially during high-speed driving or in urban traffic, engine noise, road noise, wind noise, etc. all significantly affect the riding experience of passengers. Therefore, improving the audio environment inside the vehicle and reducing unnecessary noise have become an important research direction in automotive design and manufacturing.

[0003] Active Noise Control (ANC) technology, as an effective noise suppression solution, can detect and analyze noise in real time and generate an anti-phase sound wave through the use of microphones, speakers, and signal processing algorithms, thereby effectively canceling out external noise. This technology can not only improve riding comfort but also save the use of sound insulation materials, reduce the overall weight of the vehicle to a certain extent, and optimize vehicle design.

[0004] In current ANC technology, obtaining rotational speed information is an essential step. The rotational speed information mainly serves as a reference for the ANC system and is used to generate an anti-phase sound wave opposite to the noise phase. In the prior art, the acquisition of rotational speed information is usually achieved through the CAN bus. However, the data transmission speed of the CAN bus is limited, resulting in a relatively high delay in obtaining the rotational speed signal, which affects the real-time performance and noise reduction effect of the ANC system. At the same time, when facing the need for higher-precision signal acquisition, the CAN bus has problems with insufficient precision, which affects the noise reduction cancellation effect. In order to improve the precision, more complex hardware and software support are required, further increasing the complexity and cost of the system.

[0005] Therefore, there has also been a proposed solution to use a vibration sensor to replace the CAN bus for obtaining rotational speed information. For example, the invention patent with the patent number CN118538192A discloses a method for collecting active noise reduction signals using a vibration sensor. The rotational speed information is obtained by acquiring vibration signals through the vibration sensor. This method has well solved the problems generated by using the CAN bus for signal extraction and transmission to a certain extent. However, when facing complex driving conditions or when dealing with commercial vehicles with higher noise reduction requirements, there will be problems such as insufficient precision in extracting vibration signals and delays in signal processing, thus affecting the precision of the rotational speed information and reducing the overall noise reduction effect. Moreover, the existing vibration signal extraction methods cannot adapt to the noise changes under different driving conditions, affecting the adaptability of the ANC system. Summary of the Invention

[0006] The present invention aims to provide a method and system for active noise reduction in automobiles, so as to solve the problems that the extraction accuracy of the existing engine vibration signal is insufficient, resulting in low accuracy of obtaining rotational speed information, and there is a delay and it cannot meet higher noise reduction requirements.

[0007] To achieve the above object, the present invention adopts the following technical solutions. A method for active noise reduction in an automobile includes a first vibration sensor installed near a commercial vehicle engine and a second vibration sensor installed near the trunk of the commercial vehicle; and the two vibration sensors are respectively connected to a first ANC controller.

[0008] The environmental parameters of the vehicle and the operating state of the engine are obtained and determined in real time, and the corresponding vibration sensor is selected according to the determination conditions to obtain the vibration signal of the engine.

[0009] The rotational speed information of the current engine is obtained according to the vibration signal and engine parameters according to the set calculation mode; the rotational speed information is input into the first ANC controller, and the first ANC controller outputs noise reduction information.

[0010] This solution also provides a system for active noise reduction in an automobile, which is applied to the above method for active noise reduction in an automobile. It includes a first vibration sensor installed near a commercial vehicle engine and a second vibration sensor installed near the trunk of the commercial vehicle; wherein the first vibration sensor and the second vibration sensor are respectively connected to the first ANC controller through a wire harness, and the first ANC controller is connected to the vehicle control unit MCU for processing low-frequency noise; it also includes a second ANC controller, which is connected to the vehicle control unit MCU for processing high-frequency noise.

[0011] The principle and advantages of this solution are as follows:

[0012] When collecting the existing engine vibration signal, the CAN bus is generally used to obtain the rotational speed information. However, due to the transmission performance of the CAN bus, the delay is too large. And because the fixed time interval for the ECU to send CAN data is usually 10 ms to 20 ms, the received rotational speed information also has the same time delay. For the ANC (active noise control) system, the rotational speed information directly corresponds to the frequency order of the noise, and too large a delay will significantly affect the real-time performance and noise reduction effect of the ANC system.

[0013] At present, although there is a method of using vibration sensors to directly collect vibration signals to obtain rotational speed information, in the face of complex driving conditions or high-noise reduction demand scenarios such as commercial vehicles, the existing technology still has difficulty in accurately obtaining rotational speed information. Through our analysis, it is found that this limitation mainly stems from the dependence on engine rotational speed information in traditional designs, focusing on the later-stage accuracy processing of the obtained rotational speed information, but ignoring that the rotational speed information is mainly calculated from vibration signals, and the vibration signals are mainly obtained by collecting the engine. Thus, there is also a technical bias that generally believes that vibration sensors can only be installed near the engine, ignoring the influence of other factors of the engine itself on the vibration signal collection effect.

[0014] Especially under certain extreme conditions, such as when the engine temperature is too high or the vibration amplitude is too large, the installation position near the engine may not meet the accuracy requirements of data collection. Although it can be compensated by later-stage data processing, this does not fundamentally solve the source problem. And under the limitation of the collection object area, the existing technology usually also believes that only one collection point needs to be set near the engine to collect the engine signal. Setting too many collection points in one area has no advantage, and there are also problems of signal interference, resource waste, and cost increase. And the existing such design can also meet general noise reduction requirements. In the case of low noise reduction requirements, adding collection points or improving sensors will not be considered, so as not to increase costs.

[0015] These limitations cause the existing technology to have difficulty in accurately collecting vibration signals in the face of different driving conditions (such as high-speed driving, rapid acceleration, heavy load, etc.), thus making it difficult to obtain accurate rotational speed information, restricting the noise reduction performance of the ANC system. Especially in scenarios with higher noise reduction requirements such as commercial vehicles, the deficiencies of the existing technology are more obvious and cannot meet the increasing comfort and driving experience requirements. For example, in a high-temperature environment, the vibration sensor near the engine may cause the collected data to be distorted due to thermal drift or material performance degradation; on a bumpy road surface or during rapid acceleration, the data of a single collection point may not comprehensively reflect the vibration characteristics of the vehicle, resulting in the ANC system being unable to accurately identify and cancel noise. Therefore, it is urgent to explore more efficient and accurate vibration signal collection methods to fundamentally improve the accuracy of rotational speed information and enhance the noise reduction effect of the ANC system.

[0016] This solution breaks through the limitation that the acquisition of engine vibration signals can only be carried out near the engine, and realizes the influence of the engine's own factors on the acquisition effect. Creatively, a second acquisition point is set at one end of the trunk far from the engine. When the influence factors of the engine itself are large, the acquisition point can be flexibly switched to ensure the timeliness and stability of the acquisition of engine vibration signals, reduce interference factors, improve the signal acquisition efficiency, thereby improving the accuracy of rotational speed information, and solving the problem that the noise reduction effect is insufficient and cannot meet the high-precision noise reduction requirements. Applying this solution greatly reduces the time for rotational speed extraction and makes the extracted signal more accurate, and the rotational speed information obtained thereby is more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic flowchart of the process of a method for active noise reduction of an automobile according to the present invention.

[0018] Figure 2 It is a schematic structural installation diagram of a system for active noise reduction of an automobile according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The following is a further detailed description through specific embodiments:

[0020] Embodiment 1

[0021] In a method for active noise reduction of an automobile in this embodiment, vibration sensors are respectively installed at the positions of the engine and the vehicle trunk, and according to the operating states of the engine and the vehicle, a suitable vibration sensor is flexibly selected to collect the vibration signals of the engine, thereby reducing the signal acquisition delay and effectively eliminating interference factors, ensuring the timeliness and accuracy of signal acquisition, so as to improve the stability and accuracy of rotational speed information, and thus improve the noise reduction accuracy and effect. In this embodiment, as shown in the attached Figure 1 figure, it includes a first vibration sensor installed near the engine of a commercial vehicle and a second vibration sensor installed near the trunk of the commercial vehicle; and the two vibration sensors are respectively connected to a first ANC controller, and the first ANC controller is connected to the vehicle ECU (engine control unit).

[0022] In this embodiment, the first vibration sensor is installed on a mounting surface at a distance of 1-3 cm from the engine, and the stiffness of this mounting surface needs to be relatively large, and preferably at a position where the engine vibration is relatively large, such as the mounting surface can be selected as the engine housing, the power assembly or the mounting surface, so as to ensure the stability of the installation of the first vibration sensor and be able to effectively collect the vibration signals of the engine. The second vibration sensor is installed on the housing of the trunk of the commercial vehicle and needs to be far away from the area where the glass is located to ensure the stability and safety of the installation of the second vibration sensor and be able to obtain effective engine vibration signals.

[0023] The present solution creatively discovers that in addition to the vicinity of the engine being used as a vibration signal acquisition point, the vehicle's trunk can also effectively and accurately collect the engine vibration signal. Since the trunk is usually far from other vibration sources (such as tires and drive systems), there is less interference near the trunk, enabling the engine vibration characteristics to be captured more accurately. Moreover, the trunk is directly connected to the vehicle body frame, and the vibration transmission path is relatively direct. The engine vibration can also be transmitted to the trunk through rigid structures such as the vehicle body frame and chassis. Even though the distance may seem far, the vibration signal can still be effectively transmitted. Therefore, the second vibration sensor installed at the trunk can also capture the engine vibration signal more clearly. At the same time, because the trunk space is large, it is more convenient to install the sensor and it is not easily affected by the external environment (such as dust and water vapor).

[0024] In addition, the engine vibration is mainly low-frequency, and the low-frequency vibration attenuates slowly in the vehicle body structure, which can also ensure its effective transmission to the trunk. Even for different vehicle models, since their trunk structures are similar, it can be applicable to the installation and data collection of different vehicle models. In contrast, other positions of the vehicle cannot meet the accurate acquisition of vibration signals due to excessive interference or harsh environments. This also overcomes the inherent thinking in the prior art that the acquisition of engine vibration signals can only be carried out near the engine, and a breakthrough is made by setting the relatively distant trunk as the second acquisition point for engine vibration signals.

[0025] In this embodiment, both vibration sensors are connected to the circuit of the first ANC controller, and the first ANC controller is used to perform noise reduction processing on the low-frequency noise signal emitted by the engine to ensure the effective processing and analysis of the low-frequency signal. At the same time, a second ANC controller is also installed in the vehicle, which is mainly used for noise reduction processing of high-frequency noise signals emitted by other vehicle systems or the external environment except the engine. Two ANC systems are used to analyze and process the high and low frequency signals respectively to ensure the accuracy and effectiveness of the noise reduction processing, and at the same time, it can also avoid causing co-frequency interference and situations such as overlapping conflicts or delays. The first ANC controller is mainly used for processing the low-frequency noise signal of the engine to ensure more accurate and timely processing.

[0026] Obtain and determine the environmental parameters of the vehicle and the operating state of the engine in real time, and select the corresponding vibration sensor to obtain the engine vibration signal according to the determination conditions.

[0027] In this embodiment, the environmental parameters include the frequency of the vehicle interior environmental noise and the environmental vibration state. Devices such as microphones, accelerometers, and other sensors installed in the vehicle system are used to obtain the noise frequency and vibration state inside the vehicle, etc., so as to determine the influence degree brought by the current engine noise of the vehicle. The operating state of the engine includes the engine temperature and the engine power consumption. In this embodiment, the ECU (Engine Control Unit) can comprehensively judge the engine temperature state by receiving the data of each sensor; at the same time, the ECU directly monitors the operating state of the engine, including the fuel injection amount, the intake air amount, the rotational speed, etc., and calculates the real-time power consumption of the engine through the built-in algorithm. The current vehicle operating state is judged according to the information obtained in real time, so as to flexibly select a suitable vibration sensor to collect the vibration signal of the engine, ensure the accuracy and stability of signal collection, reduce interference factors, improve the collection efficiency, and reduce the delay.

[0028] In this embodiment, the judgment conditions include the following two modes:

[0029] 1. Temperature judgment.

[0030] According to the engine temperature obtained in real time, judge the current operating temperature of the engine. When the temperature ≥ the set threshold and lasts for T time, switch to the second vibration sensor to collect the vibration signal of the engine, otherwise use the first vibration sensor.

[0031] When it is detected that the current engine temperature is too high, it indicates that the current engine is in a high-load or long-time operating state, such as working conditions like high-speed driving, climbing, or towing. At this time, the heat generated by internal combustion and friction in the engine increases, causing the engine temperature to rise. In this state, it may cause the sensitivity of the first vibration sensor to decrease or the signal to drift. At the same time, the thermal expansion of engine components may change the vibration characteristics, increasing the signal noise and affecting the collection accuracy and timeliness of the first vibration sensor. At this time, it is necessary to switch to the second vibration sensor to collect the vibration signal of the engine to ensure the accuracy and effectiveness of the collected signal, thereby improving the accuracy of the engine speed information.

[0032] In this embodiment, the set threshold is 90 - 120 °C, and the duration T is 20 minutes to 50 minutes. The specific values can be set according to the model and performance of the engine. For example, when the temperature exceeds 90 °C, start timing, and if it lasts for more than 20 minutes, automatically switch to the second vibration sensor.

[0033] 2. Frequency ratio judgment.

[0034] According to the real-time acquisition of the vehicle's internal environmental noise frequency and environmental vibration state, the current noise frequency ratio is analyzed, that is, the ratio of the current high-frequency noise to the low-frequency noise is analyzed to determine the degree of influence of the engine noise on the overall noise. At the same time, the current engine power consumption value is obtained. When the low-frequency ratio is less than the set value and lasts for R time, the engine power consumption is low, then the No. 1 vibration sensor is stopped, and the No. 2 vibration sensor is used to collect the vibration signal of the vehicle noise.

[0035] When the vehicle's own high-frequency noise processing system, that is, not a noise reduction system for the engine, in this embodiment, it can be understood as the second ANC system, when multiple noise signals are collected, they are compared with the engine vibration signal collected by the current vibration sensor No. 1. When it is analyzed that the current high-frequency noise signal accounts for a large proportion, and the low-frequency noise signal accounts for a small proportion, in this embodiment, the low-frequency proportion is set to <20%, and the power consumption of the current vehicle engine is detected at the same time. When the low-frequency proportion lasts for R time, such as R = 2 minutes, and the engine power consumption is low. It indicates that the external noise of the current vehicle is greater than the noise generated by the engine itself, and the engine noise itself is also small, indicating that the current vehicle may be in a low-load operation state (such as idling, low-speed driving or complex road conditions, etc.). At this time, the noise generated by the engine itself will be relatively low, and the noise caused by other operating systems inside the vehicle, such as electrical systems, exhaust systems, air-conditioning compressors, wind noise, vibrations and other external environments will be greater than the noise caused by the engine, and affect the overall riding experience in the vehicle. At this time, for noise reduction processing, the noise of the engine can be ignored, and more attention needs to be paid to the noise processing of the external high-frequency environment.

[0036] Therefore, when it is detected that the current low-frequency noise of the vehicle accounts for a small proportion, while the high-frequency noise accounts for a large proportion, the No. 1 vibration sensor is stopped and switched to the No. 2 vibration sensor to assist in collecting the noise and vibration signals inside the vehicle. In this way, the No. 2 vibration sensor is used to help the second ANC system process high-frequency noise signals, improve the overall noise reduction processing effect in the vehicle, and further improve the utilization efficiency of the No. 2 vibration sensor.

[0037] According to the state of the engine, the collection points of the vibration sensor are flexibly switched to ensure the stability, timeliness and accuracy of the vibration signal collection, so as to obtain accurate vibration signals. At the same time, the vibration sensor is used to extract the vibration signal of the engine to reduce the delay and make the information more stable, so as to ensure the accuracy of the speed information.

[0038] The current engine speed information is calculated based on the acquired vibration signal and engine parameters according to the set calculation mode.

[0039] In this embodiment, the engine parameters include the number of engine strokes and cylinders of the current engine. Among them, the calculation mode is to first pass the acquired vibration signal through an ADC conversion chip to convert the analog signal into a digital signal, and then transmit the digital signal to the MCU for algorithm calculation. In this embodiment, first, the acquired digital signal is filtered according to the processing method, such as performing a second-order or fourth-order IIR filter to reduce interference signals and ensure a relatively clean signal. Then, zero-crossing detection is used to calculate the frequency of the current engine, and the engine speed is calculated based on the frequency value and engine parameters to obtain the speed information. The method of zero-crossing detection can greatly reduce the required time, reduce latency, and greatly reduce the time for speed extraction. At the same time, the acquired speed information is more accurate and stable than that obtained by CAN, eliminating the inherent transmission delay time and improving the signal acquisition efficiency.

[0040] In this embodiment, when using the first vibration sensor to collect the vibration signal of the engine, since the first vibration sensor is closer to the engine and the acquisition environment is relatively enclosed, the vibration signal obtained is mostly the low-frequency signal of the engine. At this time, the processing method is to filter and clean the collected low-frequency signal to obtain an accurate vibration signal for calculating the engine speed information.

[0041] When the temperature of the engine is too high and it is switched to using the second vibration sensor to collect the vibration signal of the engine, since the second vibration sensor will also collect other vibration frequency signals in addition to the low-frequency signal generated by the engine, that is, the second vibration sensor will collect two vibration signals including low-frequency and high-frequency when collecting the vibration signal. At this time, the processing method is to filter the vibration signal collected by the second vibration sensor to filter out the high-frequency signal, retain the low-frequency signal generated by the engine, and then clean it for calculating the engine speed.

[0042] Among them, the speed calculation process is as follows: Set the low-frequency vibration signal of the engine collected by the vibration sensor as x(t), and count the number of times the vibration signal crosses zero within a unit time as N. Then the signal frequency is

[0043]

[0044] In the formula, H is the sampling time, with the unit of s. Since there are two zero-crossings (from positive to negative and from negative to positive) in a complete cycle, it is necessary to divide by 2 to calculate the accurate signal frequency.

[0045] The engine speed M is calculated based on the frequency and engine parameters as

[0046]

[0047] Where k is the engine stroke coefficient; C is the number of engine cylinders; and n is the multiple relationship between the vibration signal frequency and the ignition frequency.

[0048] The calculated rotation speed information is input into the first ANC controller, and the first ANC controller outputs the noise reduction information.

[0049] In this embodiment, the first ANC system generates an "anti-noise" signal with the opposite phase and the same amplitude as the noise signal according to the speed information obtained in time to offset the target noise. The main frequency components of the noise (such as the engine ignition frequency and its harmonics) are determined by the engine speed information, thereby optimizing the noise reduction effect of the ANC system.

[0050] In this embodiment, the spatial limitation of traditional engine vibration signal acquisition is innovatively broken through. By adding a second acquisition point in the trunk away from the engine, the interference of engine factors (such as high temperature and mechanical vibration) on signal acquisition is effectively solved. When the acquisition point near the engine is greatly affected, the system can flexibly switch to the trunk acquisition point to ensure the stability and real-time performance of vibration signal acquisition, significantly improve the signal quality, and thus improve the accuracy of speed information. It not only overcomes the shortcomings of traditional methods in noise reduction accuracy and efficiency, but also greatly shortens the speed extraction time, making the obtained speed information more accurate and reliable.

[0051] At the same time, the vibration sensor is used to extract the vibration signal to obtain the speed information, which significantly reduces the signal delay and provides more efficient input data for the ANC algorithm. Combined with the zero-crossing detection technology, the calculation efficiency is further optimized, the system response time is reduced, and the noise reduction performance is more agile. The ability to achieve flexible acquisition, efficient processing and precise noise reduction can adapt to complex and changing operating environments, provide strong technical support for high-precision active noise control, and achieve a significant improvement in noise reduction effects.

[0052] Example 2

[0053] In this embodiment, a system for active noise reduction of an automobile is provided, which is applied to the above-mentioned method for active noise reduction of an automobile, as shown in the attached Figure 2 As shown, it includes a vibration sensor No. 1 installed near the engine of a commercial vehicle, and a vibration sensor No. 2 installed near the trunk of the commercial vehicle. The vibration sensor No. 1 and the vibration sensor No. 2 are respectively connected to the first ANC controller through a wiring harness. The first ANC controller is connected to the vehicle control unit MCU and is mainly used to process the low-frequency noise generated by the engine. At the same time, a second ANC controller is also provided in the vehicle, which is connected to the vehicle control unit MCU and is mainly used to process other high-frequency noise generated in the vehicle's internal environment.

[0054] In this embodiment, it also includes that when it is determined that the low-frequency noise in the current vehicle is < 20% and the engine power consumption is low and the duration exceeds 2 minutes, it indicates that the external high-frequency noise of the current vehicle is large. At this time, the first vibration sensor is stopped, and the second vibration sensor is used to collect the vibration signal of the vehicle noise. The low-frequency noise collected by the second vibration sensor is filtered and then cleaned to obtain high-frequency noise and transmitted to the first ANC controller, so that the first ANC controller participates in the noise reduction processing of the external high-frequency noise. If the current low-frequency noise is even less and can be ignored, the step of filtering the low-frequency noise can also be omitted, and the collected noise signal is directly transmitted to the first ANC controller for the first ANC controller to perform noise reduction processing.

[0055] In this embodiment, the first ANC controller can process high-frequency signals and also low-frequency signals. Just to avoid conflicts with the second ANC controller, the first ANC controller is specifically set to the processing mode for the low-frequency signals of the engine, while the second ANC controller in the vehicle is mainly for the processing of high-frequency signals. When the low-frequency noise of the engine is less, the first ANC controller is switched to the processing mode for high-frequency signals to assist in the noise reduction processing of high-frequency noise. Thus, the utilization efficiency of the first ANC controller and the vibration sensor in the vehicle is fully improved, resource waste is avoided, and the noise reduction effect inside the vehicle can be further improved, making the noise reduction more accurate and stable and improving the comfort inside the vehicle.

[0056] Embodiment 3

[0057] In this embodiment, the process of generating the anti-noise signal is mainly as follows: a reference signal x(d) is generated according to the obtained rotational speed information, which is usually a sine wave or square wave signal of the engine ignition frequency and its harmonics. Then the reference signal x(d) can be expressed as

[0058]

[0059] where A k is the amplitude; f k is the engine ignition frequency and its harmonic frequencies; φk is the phase.

[0060] Thus, the ANC controller uses an adaptive filtering algorithm (such as the least mean square error (LMS) algorithm) to generate the anti-noise signal y(d), which can be expressed as y(d) = W T (d)x(d); where W(d) is the filter coefficient vector; x(d) is the reference signal vector. The noise reduction information is output through the ANC controller.

[0061] At the same time, in this embodiment, it also includes using an error microphone to collect the residual noise signal e(d) for adjusting the filter coefficient: e(d) = x(d) - y(d); where x(d) is the noise signal inside the vehicle obtained.

[0062] Update the filter coefficients using the LMS algorithm: W(d + 1) = W(d) + μ·e(d)·x(d); where μ is the step factor that controls the convergence rate to achieve the dynamic adjustment of the anti-noise signal. By collecting the residual noise signal in real time and combining with the adaptive filtering algorithm, the filter coefficients are dynamically updated to generate an anti-noise signal with a phase opposite to and an amplitude equal to that of the noise signal, thereby precisely canceling the noise. It realizes real-time noise reduction, precise cancellation, and multi-band control, and can effectively cope with complex environments such as engine speed changes and road noise fluctuations.

[0063] Output the anti-noise signal y(d) through the speaker to cancel it with the original noise signal x(d) to achieve noise reduction.

[0064] In this embodiment, the rotational speed information is input into the ANC controller to generate a reference signal and combined with the adaptive filtering algorithm to achieve the active control of engine noise. It automatically adjusts according to the noise change without manual intervention, and at the same time quickly converges to the optimal noise reduction state to reduce the delay. In addition, the dynamic adjustment can also optimize the output power of the anti-noise signal to avoid energy waste. And through real-time adjustment and feedback, the ANC system can maintain stable noise reduction performance in scenarios with multiple positions and multiple noise sources, quickly adapt to the changes in noise frequency and amplitude, ensure that the noise reduction effect always matches the current noise state, effectively reduce engine noise, and improve the in-vehicle acoustic comfort.

[0065] The above are only the embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics well known in the art are not described in detail herein. It should be noted that for those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be subject to the content of its claims, and the specific implementation manners described in the specification can be used to explain the content of the claims.

Claims

1. A method for active noise reduction of an automobile, characterized in that: It includes a No. 1 vibration sensor installed near the engine of the commercial vehicle, and a No. 2 vibration sensor installed near the trunk of the commercial vehicle; and the two vibration sensors are respectively connected to the first ANC controller; Acquire and determine the environmental parameters of the vehicle and the operating status of the engine in real time, and select the corresponding vibration sensor to obtain the vibration signal of the engine according to the determination conditions; The current engine speed information is obtained according to the vibration signal and the engine parameters in accordance with the set calculation mode; the speed information is input into the first ANC controller, and the first ANC controller outputs the noise reduction information.

2. The method for active noise reduction of an automobile according to claim 1, characterized in that: The environmental parameters include the frequency and vibration state of the vehicle's internal environmental noise; the engine's operating state includes engine temperature and engine power consumption.

3. The method for active noise reduction of an automobile according to claim 2, characterized in that: The determination conditions include the following two modes: Temperature judgment: judge the current engine operating temperature. When the temperature is ≥ the set threshold and lasts for T time, switch to the second vibration sensor to collect the vibration signal of the engine. Otherwise, use the first vibration sensor. Frequency ratio judgment, judge the current high and low frequency ratio. When the low frequency ratio is less than the set value and lasts for R time, the No. 1 vibration sensor is stopped and the No. 2 vibration sensor is used to collect the vibration signal of the vehicle noise.

4. The method for active noise reduction of an automobile according to claim 1, characterized in that: The calculation mode is to first filter the acquired vibration signal according to the processing method, then use zero-crossing detection to calculate the current engine frequency, calculate the engine speed according to the frequency value and engine parameters, and obtain the speed information.

5. The method for active noise reduction of an automobile according to claim 4, characterized in that: The engine parameters include the number of engine strokes and the number of cylinders.

6. The method for active noise reduction of an automobile according to claim 5, characterized in that: The speed information M is Where k is the engine stroke coefficient; C is the number of engine cylinders; and n is the multiple relationship between the vibration signal frequency and the ignition frequency.

7. The method for active noise reduction of an automobile according to claim 1, characterized in that: It also includes collecting residual noise signals, adjusting filter coefficients in real time, and generating anti-noise signals.

8. A system for active noise reduction in an automobile, characterized in that: The method for active noise reduction of an automobile as described in any one of claims 1 to 7 comprises a first vibration sensor installed near the engine of a commercial vehicle, and a second vibration sensor installed near the trunk of the commercial vehicle; wherein the first vibration sensor and the second vibration sensor are respectively connected to a first ANC controller through a wiring harness, and the first ANC controller is connected to an automobile control unit MCU for processing low-frequency noise; and also comprises a second ANC controller connected to the automobile control unit MCU for processing high-frequency noise.

9. The system for active noise reduction of a vehicle according to claim 8, characterized in that: The vibration sensor No. 1 is installed on a mounting surface 1-3 cm away from the engine; the mounting surface needs to have a large rigidity; the mounting surface includes the engine housing, powertrain or suspension surface.

10. The system for active noise reduction of a vehicle according to claim 8, characterized in that: The second vibration sensor is installed on the shell of the trunk of the commercial vehicle and is far away from the area where the glass is located.

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