An active noise reduction method and microphone vibration damping device for suppressing divergence.

Abstract

This invention provides an active noise cancellation method and microphone vibration damping device that suppresses divergence, belonging to the field of automotive active noise cancellation technology. It detects the cabin's sealing status using sensors on the doors, windows, and sunroof. If sealed, noise signals are collected using the error on the microphone vibration damping device and a reference microphone. These signals are then processed by an active noise cancellation filter to generate a secondary noise signal, which is played through a speaker. If open, the engine speed is read from the vehicle's CAN signal to generate a reference noise signal, which is also played. The dashboard displays the cabin sealing status and the active noise cancellation system's operating status, determined based on the noise signal collection and noise cancellation signal playback. This invention automatically switches noise cancellation modes according to the cabin's sealing status, effectively reducing interior noise when sealed and appropriately playing reference noise when open, minimizing the impact on the system filter's robustness. Relevant information is displayed on the dashboard, allowing users to intuitively understand the cabin status and system operation.

Description

Technical Field

[0001] This invention belongs to the field of active noise cancellation technology for automobiles, specifically relating to an active noise cancellation method that suppresses divergence and a microphone vibration damping device. Background Technology

[0002] As the automotive industry rapidly develops towards intelligence, electrification, and comfort, in-vehicle noise control has become one of the technologies to enhance the driving experience. Active Noise Cancellation (ANC) technology collects in-vehicle noise signals and generates inverse sound waves in real time to cancel them out, showing significant advantages, especially in low-frequency ranges such as engine noise, road noise, and wind noise.

[0003] In related technologies, active noise cancellation systems are based on the fact that the noise environment inside the vehicle changes from a closed space to an open space, and external wind noise and road noise are randomly mixed in, resulting in a large amount of invalid interference in the noise signal collected in real time. This makes it impossible for the parameters of the active noise cancellation filter to be stably adapted, resulting in problems such as noise reduction divergence and decreased robustness.

[0004] In automotive scenarios, engine vibration, road bumps, and vehicle body resonance are transmitted to the microphone through the installation structure. Existing vibration reduction solutions mostly use rubber pads for vibration reduction, which has limited effect. Furthermore, the microphone installation lacks a clear displacement constraint design, and vibration can cause the microphone position to shift and the shell to vibrate. This causes the collected noise signal to be superimposed with vibration interference, resulting in signal amplitude fluctuations and phase shifts. Consequently, the secondary noise generated afterward cannot be accurately canceled out with the original noise, affecting the noise reduction effect.

[0005] Microphones using related technologies are prone to distance or angular deviations during installation, leading to a mismatch in the acquisition range of the reference and error microphones. Vibration damping devices lack constraints on the microphone's degrees of freedom; lateral displacement can cause positional deviations in the noise signals acquired by the microphones. Inconsistent signal characteristics from the same noise source acquired by two microphones affect the accuracy of secondary noise generation, resulting in decreased noise reduction precision. Summary of the Invention

[0006] This invention provides an active noise cancellation method that suppresses divergence. A clamping mechanism is used to secure the error and reference microphones. At the same time, a two-stage vibration reduction measure using springs and vibration damping pads is adopted to effectively reduce the impact of vehicle vibration and noise on the error and reference microphones, effectively reducing the vibration of the microphone itself and the transmission of structural noise, thereby achieving effective suppression of divergence in the active noise cancellation system.

[0007] The methods include:

[0008] S101: Detects the airtightness of the vehicle's cab based on signals from door sensors, window sensors, and sunroof sensors;

[0009] S102: When the cab is closed, noise signals inside the vehicle are collected through the error microphone and reference microphone installed by the microphone vibration damping device; when the cab is open, the collection of noise signals is turned off.

[0010] S103: When the cab is sealed, a secondary noise signal is generated based on the collected noise signal through an active noise reduction filter;

[0011] S104: Play secondary noise signals through a speaker;

[0012] S105: When the cab is opened, read the engine speed from the vehicle's CAN signal;

[0013] S106: Generate a reference noise signal based on engine speed;

[0014] S107: Play the reference noise signal through the speaker;

[0015] S108: Displays the cab sealing status and the operating status of the active noise reduction system on the instrument panel. The operating status is based on the noise signal acquisition and noise reduction signal playback.

[0016] It should be further explained that S101 specifically includes the following methods:

[0017] Connect the door sensor, window sensor, and sunroof sensor to the signal input interface of the vehicle body control module (BCM) via signal lines.

[0018] An RC filter circuit is installed inside the Body Control Module (BCM). The input of the RC filter circuit is connected to the signal lines of each sensor to filter the raw electrical signals output by the sensors.

[0019] The Body Control Module (BCM) reads sensor signals, converts the mechanical switch signals of the door sensors into 0-5V level signals, converts the Hall signals of the window sensors into pulse counting signals, and converts the photoelectric signals of the sunroof sensors into switch levels.

[0020] The Body Control Module (BCM) presets the closing status thresholds for doors, windows, and sunroof: a door signal of 5V is considered closed, and 0V is considered open; a window pulse count reaching a preset value is considered closed, and not reaching it is considered open; a sunroof signal of 5V is considered closed, and 0V is considered open; when all doors, windows, and sunroofs are determined to be closed, a cab sealing status signal is generated; otherwise, a cab opening status signal is generated.

[0021] The Body Control Module (BCM) sends signals indicating whether the cab is closed or open to the active noise cancellation system.

[0022] It should be further explained that S102 specifically includes the following methods:

[0023] The analog voltage signals from the error microphone and the reference microphone are acquired and converted into digital signals.

[0024] The converted digital signal is then filtered.

[0025] When the cab is open, a control signal is sent to the microphone preamplifier to cut off the microphone power supply circuit and stop signal acquisition.

[0026] When the cab is sealed, an enable signal is sent to the microphone preamplifier to connect the microphone power supply circuit and start signal acquisition.

[0027] The acquired and processed digital signal is transmitted to the active noise reduction system through the parallel interface of the digital signal processor.

[0028] It should be further noted that S106 specifically includes the following methods:

[0029] An engine speed reference noise signal mapping module is set in the vehicle's electronic control unit to pre-store the reference noise signal characteristic parameters corresponding to different engine speeds;

[0030] The engine speed signal read in step S105 is obtained from the vehicle's CAN bus and transmitted to the engine speed reference noise signal mapping module.

[0031] Based on the received engine speed signal, find the corresponding reference noise signal characteristic parameters;

[0032] Based on the found characteristic parameters of the reference noise signal, a reference noise signal is generated, and the frequency and amplitude of the signal are adjusted according to the parameters using the principle of a signal generator.

[0033] The generated reference noise signal is transmitted to the speaker through the audio output interface.

[0034] It should be further noted that S107 specifically includes the following methods:

[0035] The digital reference noise signal is converted into multiple analog voltage signals using a multi-channel digital-to-analog converter;

[0036] A differential amplifier is used to convert the voltage signal into a balanced audio signal, and a low-pass filter is used to eliminate high-frequency quantization noise.

[0037] An audio power amplifier is used to amplify the balanced audio signal to drive the vehicle speaker system;

[0038] The power amplifier chip junction temperature is monitored in real time by a temperature sensor, and the output power is reduced when the temperature exceeds a threshold.

[0039] It should be further explained that S108 specifically includes the following methods:

[0040] The status register stores the cab sealing status indicator and the active noise reduction system operation status indicator in real time.

[0041] The instrument panel display controller reads status data from the status register and performs display data format conversion;

[0042] The icon display unit displays the cab sealing status icon and the active noise reduction system operation status icon in a designated area of ​​the instrument panel;

[0043] A multi-color LED driver circuit is used to control the display color and flashing frequency of the status indicator light.

[0044] It should be further noted that S102 also includes the following steps:

[0045] The microphone vibration damping device is installed on the inner side wall of the vehicle's cab. The inner connector is rigidly connected to the cab body through the mounting bolt holes of the outer connector to limit the freedom of the clamping strut.

[0046] The error microphone and the reference microphone are fixed to the microphone vibration damping device, and the vibration isolation pad is clamped to the microphone by the pre-tightening spring.

[0047] When the cab is sealed, noise signal acquisition is activated, and the microphone vibration damping device dampens vibration through springs and vibration isolation pads.

[0048] When the cab is opened, noise signal acquisition is turned off, and the microphone damping device maintains spring preload to clamp the microphone.

[0049] The longitudinal displacement of the clamping strut is monitored by a displacement sensor, and a fault signal is sent to the instrument panel when the displacement exceeds a threshold.

[0050] It should be further noted that S102 also includes the following steps:

[0051] A damping ring is fitted on the outside of the spring. The damping ring is made of a high-molecular elastic material, wraps around the outer surface of the spring and contacts the inner groove of the outer connector to form a friction damping structure.

[0052] A multi-layer composite structure is set at the bottom of the vibration isolation pad, including an upper metal plate, a middle rubber layer and a lower metal plate. The metal plate and the rubber layer are bonded together by a vulcanization process to form a composite vibration damping layer that combines rigidity and flexibility.

[0053] A corrugated buffer pad is installed between the contact surfaces of the clamping column and the vibration isolation pad. The corrugated buffer pad is formed by stamping thin metal sheet and embedded in the groove at the front end of the clamping column.

[0054] An arc-shaped groove is provided in the area where the bottom support surface of the thrust plate contacts the spring. The arc-shaped groove matches the compression direction of the spring, so that the force on the spring is evenly distributed.

[0055] A limiting protrusion is provided on the outer edge of the vibration isolation pad. The limiting protrusion forms a sliding fit with the inner wall of the outer connector to limit the displacement of the vibration isolation pad in the lateral direction.

[0056] The present invention also provides a microphone vibration damping device, comprising: an outer connector and an inner connector; the inner connector is disposed inside the outer connector; and a plurality of elastic components and a plurality of support pillars are connected between the outer connector and the inner connector.

[0057] The internal connector is equipped with vibration damping pads;

[0058] The elastic components include: springs, clamping struts, and thrust plates;

[0059] One end of the clamping strut is connected to the vibration isolation pad through the inner connector, and the other end of the clamping strut is fixedly connected to one side of the thrust plate.

[0060] One end of the spring is connected to the other side of the thrust plate, and the other end of the spring is fixedly connected to the inner wall of the outer connector.

[0061] It should be further noted that the external connector has multiple mounting bolt holes for fastening the microphone vibration damping device to the vehicle body;

[0062] The cross-sections of the outer connector and the inner connector are both polygonal structures.

[0063] Multiple elastic components and multiple support columns are evenly distributed between the outer and inner connectors.

[0064] As can be seen from the above technical solutions, the present invention has the following advantages:

[0065] The active noise reduction method and microphone vibration damping device provided by this invention, which suppresses divergence, forms a two-stage vibration damping structure through the elastic absorption of springs and the damping of vibration isolation pads. This reduces the transmission of vehicle body vibration to the error microphone and reference microphone, thereby improving the fidelity of the original signal. Based on a noise reduction strategy that switches between closed and open cab states, in the closed state, reverse secondary noise is generated by real-time noise acquisition to achieve precise noise reduction; in the open state, a matching reference noise is generated based on engine speed to avoid the decrease in robustness of the noise reduction filter caused by the open space. Both modes cover the noise reduction needs of all operating conditions.

[0066] When the cab is open and noise collection is stopped, the vibration damping device maintains spring preload, ensuring the vibration isolation pads continuously clamp the microphone. This prevents microphone displacement, impacts, or loose wiring due to vehicle vibration, extending microphone lifespan and reducing equipment failure rate. A built-in displacement sensor monitors the longitudinal displacement of the clamping strut; when displacement exceeds a threshold, a fault signal is fed back and marked on the dashboard, allowing users to promptly detect vibration damping device malfunctions. Clearly defining the microphone vibration damping device's installation location and rigid connection requirements restricts the clamping strut to longitudinal movement only, preventing microphone offset due to lateral displacement. This ensures consistent and stable signal acquisition, improving the practicality, reliability, and user experience of the active noise cancellation system, making it suitable for in-vehicle active noise cancellation scenarios. Attached Figure Description

[0067] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0068] Figure 1 The flowchart shows an active noise reduction method that suppresses divergence.

[0069] Figure 2 This is a schematic diagram of a microphone vibration damping device;

[0070] Figure 3 This is a schematic diagram of a microphone vibration damping device. Detailed Implementation

[0071] The active noise reduction method with divergence suppression involved in this application will be described in detail below. Specific details such as particular system structures and techniques are set forth for illustrative purposes and not for limitation, so as to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details.

[0072] It should be understood that, when used in this specification, terms include indicating the presence of a described feature, integral, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The terms include, encompass, have, and variations thereof mean including but not limited to, unless otherwise specifically emphasized.

[0073] The statements such as "one embodiment" or "some embodiments" described in this application mean that one or more embodiments of this application include the specific features, structures, or characteristics described in that embodiment. Therefore, the statements such as "in one embodiment," "in some embodiments," "in other embodiments," and "in still other embodiments" in this application do not necessarily refer to the same embodiment, but rather mean one or more, but not all, embodiments, unless otherwise specifically emphasized.

[0074] The technical solutions of the embodiments of the present invention 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0075] Please see Figure 1 The diagram shows a flowchart of an active noise reduction method for suppressing divergence in a specific embodiment. The method includes:

[0076] S101: Detects the airtightness of the vehicle's cab based on signals from door sensors, window sensors, and sunroof sensors.

[0077] S101 specifically includes the following methods:

[0078] S1011: Connect the door sensor, window sensor, and sunroof sensor to the signal input interface of the vehicle body control module (BCM) via signal lines. The door sensor uses a contact mechanical switch, the window sensor uses a Hall position sensor, and the sunroof sensor uses a photoelectric beam sensor.

[0079] Step S1012: An RC filter circuit is set inside the Body Control Module (BCM). The input terminal of the RC filter circuit is connected to the signal lines of each sensor to filter the raw electrical signals output by the sensors.

[0080] Step S1013: The Body Control Module (BCM) reads the sensor signals, converts the mechanical switch signal of the door sensor into a 0-5V level signal, converts the Hall signal of the window sensor into a pulse counting signal, and converts the photoelectric signal of the sunroof sensor into a switch level.

[0081] S1014: Body Control Module (BCM) presets the closing status thresholds for doors, windows, and sunroof: a door signal of 5V is considered closed, and 0V is considered open; a window pulse count reaching a preset value is considered closed, and not reaching it is considered open; a sunroof signal of 5V is considered closed, and 0V is considered open; when all doors, windows, and sunroofs are considered closed, a cab sealing status signal is generated; otherwise, a cab opening status signal is generated.

[0082] Step S1015: The Body Control Module (BCM) sends the cab sealing or cab opening status signal to the active noise cancellation system.

[0083] S102: When the cab is closed, noise signals inside the vehicle are collected through the error microphone and reference microphone installed by the microphone vibration damping device; when the cab is open, the collection of noise signals is turned off.

[0084] It should be noted that the error microphone is located inside the passenger compartment and is used to monitor the acoustic environment after preliminary noise reduction processing. The acquisition process involves the error microphone diaphragm being clamped and fixed by vibration isolation pads to pick up sound waves propagating in the air inside the carriage. The vibration of the diaphragm is converted into a weak analog voltage signal. This analog voltage signal is then pre-amplified by a preamplifier and transmitted to the signal processing unit via a shielded cable.

[0085] In the signal processing unit, the analog signal passes through a high-pass filter to remove ultra-low frequency interference components that may still exist after being transmitted from vehicle vibrations through the damping device. It is then converted into a digital signal by an analog-to-digital converter (ADC). The digital signal represents the error or residual noise signal that needs further cancellation.

[0086] A reference microphone acquires the raw noise signal. Positioned closer to the noise source, the reference microphone captures the uncancelled raw noise. The acquisition process is as follows: the reference microphone is clamped and fixed by vibration damping pads, and its diaphragm picks up vibration noise transmitted through the vehicle body structure. The springs and vibration damping pads in the damping device play a crucial role here, attenuating the direct impact of mechanical vibrations on the microphone body and ensuring that the microphone primarily senses airborne sound rather than structural vibration. Similar to the error microphone, the generated analog voltage signal is amplified before transmission. The signal transmission path is controlled by the cab status. When the cab is detected to be open, the power supply circuit to the reference microphone preamplifier is cut off by controlling relays and other switching devices, stopping signal acquisition to prevent invalid environmental noise from interfering with the system.

[0087] S102 specifically includes the following methods:

[0088] Step S1021: Acquire the analog voltage signals of the error microphone and the reference microphone, and convert them into digital signals.

[0089] Step S1022: Filter the converted digital signal.

[0090] Step S1023: When the cab is open, send a control signal to the microphone preamplifier to cut off the microphone power supply circuit and stop signal acquisition.

[0091] Step S1024: When the cab is sealed, send an enable signal to the microphone preamplifier to connect the microphone power supply circuit and start signal acquisition.

[0092] Step S1025: The acquired and processed digital signal is transmitted to the active noise reduction system through the parallel interface of the digital signal processor.

[0093] In one embodiment, the error microphone and the reference microphone are fixed to the underside of the instrument panel by a microphone vibration damping device. The vibration damping device's isolation pads are made of nitrile rubber with a Shore hardness of 50A, and the clamping force is maintained at 25N by spring preload. The GPIO pin of the active noise cancellation system control unit is connected to a G6K-2P type relay coil, and the normally open contact of the relay is connected in series in the microphone's 3.3V power supply circuit. The microphone output signal is transmitted through a shielded coaxial cable, with the shield grounded at one end.

[0094] S103: When the cab is sealed, a secondary noise signal is generated based on the collected noise signal through an active noise reduction filter.

[0095] In some embodiments, the preamplifier amplifies the mV-level signal to the V-level, and the high-pass filter removes low-frequency vibration interference; the analog-to-digital converter quantizes the analog signal into a digital quantity, and the FPGA hardware filter retains the effective noise frequency band; the ADAU1701 compares the original noise of the reference microphone with the residual noise signal of the error microphone, adjusts the filter parameters, and generates a secondary noise digital signal with the same amplitude and opposite phase as the original noise.

[0096] S104: Play the secondary noise signal through a speaker.

[0097] In some embodiments, digital signals can be converted back to analog signals based on digital-to-analog conversion, and operational amplifiers can be used to boost the signal amplitude to match the input requirements of power amplifiers. Power amplifiers are then used to amplify low-power signals to a level sufficient to drive speakers. The speakers convert electrical signals into acoustic signals, which are superimposed on and canceled out by the original noise waves inside the vehicle, ultimately achieving effective noise reduction in a sealed environment.

[0098] S105: When the cab is opened, read the engine speed from the vehicle's CAN signal.

[0099] In some embodiments, the differential signal of the CAN bus is converted into a TTL level signal, the signal frame is received and parsed through the UART interface, the speed value is extracted, the check bit is used to verify the signal integrity, and the valid value of the previous cycle is used when the verification fails.

[0100] S106: Generate a reference noise signal based on engine speed.

[0101] S106 specifically includes the following methods:

[0102] S1061: An engine speed reference noise signal mapping module is set in the vehicle's electronic control unit, and reference noise signal characteristic parameters corresponding to different engine speeds are pre-stored. These parameters are obtained through preliminary experimental tests.

[0103] S1062: Obtain the engine speed signal read in step S105 from the vehicle's CAN bus, and transmit the speed signal to the engine speed reference noise signal mapping module.

[0104] S1063: In the engine speed reference noise signal mapping module, the corresponding reference noise signal characteristic parameters are found based on the received engine speed signal.

[0105] S1064: Generate a reference noise signal based on the found reference noise signal characteristic parameters, and adjust the frequency and amplitude of the signal according to the parameters using the signal generator principle.

[0106] S1065: Transmits the generated reference noise signal to the speaker through the audio output interface to ensure the stability and accuracy of signal transmission.

[0107] As can be seen, in step S1061, during the preliminary experimental testing, representative reference noise signals were recorded using noise measurement equipment at different engine speeds, and their characteristic parameters, such as frequency components and sound pressure levels, were extracted and stored. Step S1062 utilizes the communication protocol of the CAN bus and the signal receiving function of the interface circuit to acquire the signal. Step S1063, based on the address mapping relationship of the data, converts the engine speed into the corresponding storage address, thereby finding the corresponding reference noise signal characteristic parameters. This accurately acquires the reference noise signal characteristic parameters corresponding to the engine speed. Step S1064 employs Direct Digital Synthesis (DDS) technology to generate a reference noise signal with a specific frequency and amplitude based on the found characteristic parameters, meeting the speaker's playback requirements. Step S1065 ensures stable signal transmission to the speaker through the conductivity of the audio interface and the shielding effect of the shielding wire.

[0108] S107: Play a reference noise signal through a speaker.

[0109] S107 specifically includes the following methods:

[0110] S1071: Converts digital reference noise signals into multiple analog voltage signals via a multi-channel digital-to-analog converter.

[0111] S1072: Uses a differential amplifier to convert voltage signals into balanced audio signals and uses a low-pass filter to eliminate high-frequency quantization noise.

[0112] S1073: Uses an audio power amplifier to amplify the balanced audio signal and drive the vehicle speaker system.

[0113] S1074: Monitors the junction temperature of the power amplifier chip in real time using a temperature sensor, and reduces the output power when the temperature exceeds the threshold.

[0114] In some embodiments, level conversion matches the DAC input level, digital-to-analog conversion and filtering generate a smooth analog signal; a power amplifier boosts the signal power, and the speaker converts it into an acoustic signal, i.e., reference noise, to cancel out engine noise. The reference noise signal has high fidelity, and the power amplification ensures a sufficient sound pressure level, achieving stable noise reduction in the on state.

[0115] S108: Displays the cab sealing status and the operating status of the active noise reduction system on the instrument panel. The operating status is based on the noise signal acquisition and noise reduction signal playback.

[0116] S108 specifically includes the following methods:

[0117] S1081: Stores the cab sealing status flag and the active noise reduction system operation status flag in real time through the status register.

[0118] S1082: Use the instrument panel display controller to read status data from the status register and perform display data format conversion.

[0119] S1083: The icon display unit displays the cab sealing status icon and the active noise reduction system operation status icon in a designated area of ​​the instrument panel.

[0120] S1084: Uses a multi-color LED driver circuit to control the display color and flashing frequency of the status indicator light.

[0121] S1085: Adjust the brightness level of the status display area via the instrument panel backlight control circuit.

[0122] In one implementation of this embodiment, when the cab status or system operating status changes, the main controller updates the value of the corresponding bit in the register through a write operation. The instrument panel display controller periodically retrieves the latest status information from the register through a read operation. A matrix LCD display module with a resolution of 128×64 pixels is used. The cab sealing status icon and the active noise cancellation system operating status icon are displayed at fixed positions within a predefined area of ​​the instrument panel. Based on the value of the status register, the drive circuit automatically selects the corresponding LED color and flashing mode. The LED brightness is controlled by adjusting the duty cycle, and the LED flashing is controlled by a square wave signal. The display brightness is automatically optimized according to ambient light to ensure clear visibility under different lighting conditions, while reducing nighttime glare and improving driving comfort and safety.

[0123] In one embodiment of the present invention, based on step S102, the following will provide a possible embodiment and its specific implementation will be described in a non-limiting manner. S102 further includes the following steps:

[0124] S2011: Determine the installation position of the microphone vibration damping device in the vehicle cab. Fix it to the side wall of the cab through the mounting bolt holes 6 of the outer connector 7. Optionally, the distance from the reference microphone installation position is 10-15cm and the distance from the error microphone installation position is 5-8cm. Ensure that the inner connector 3 is rigidly connected to the cab body and limit the freedom of the clamping support 1 to only longitudinal movement.

[0125] S2012: Connect the error microphone and the reference microphone through the microphone vibration damping device. The error microphone is fixed to the front end of the clamping support 1, and the reference microphone is fixed to the outside of the inner connector 3. The spring 2 is placed on the clamping support 1, with one end abutting against the inner connector 3 and the other end abutting against the push plate 8. The pre-tightened spring 2 makes the vibration damping pad 5 clamp the microphone.

[0126] S2013: When the cab is sealed, the active noise reduction method starts noise acquisition, the microphone vibration damping device works synchronously, the vehicle vibration is transmitted to the outer connector 7 through the body, the inner connector 3 restricts the lateral displacement of the clamping strut 1, the spring 2 compresses and absorbs vibration energy, the vibration damping pad 5 dampens and attenuates vibration transmission, reduces the microphone displacement caused by vibration, and ensures the stability of the error and reference microphone acquisition signal.

[0127] S2014: When the cab is opened, the noise signal acquisition is turned off, the microphone vibration damping device enters the protection state, the spring 2 maintains the preload force to keep the vibration damping pad 5 clamping the microphone, so as to avoid the microphone being damaged by displacement due to vehicle vibration. The thrust plate 8 is rigidly connected to the clamping support 1 to maintain the stability of the mechanical structure.

[0128] S2015: The longitudinal displacement of the clamping support 1 is monitored by the displacement sensor built into the vibration damping device. When the displacement exceeds the threshold, the vibration damping device is determined to be abnormal. A fault signal is sent to the instrument panel via the CAN bus, and the microphone vibration damping abnormality is marked in the running status display of S108.

[0129] It should be noted that the outer connector 7 in S2011 is a metal stamping part with three mounting bolt holes 6 on each side, allowing the use of M6 threads with a spacing of 10cm × 10cm. It is fixed to the inner side wall of the cab by bolts, with the installation position 10-15cm away from the reference microphone. The inner connector 3 is an aluminum alloy profile, rigidly connected to the outer connector 7 through the inner and outer connector support pillars 4, ensuring no relative displacement between the inner connector 3 and the cab body. The error microphone is placed close to the inner side wall of the cab to reduce external noise interference, while the reference microphone is placed close to the outer side panel to clearly capture external noise. The rigid connection between the inner connector 3 and the vehicle body provides a reference for longitudinal movement of the clamping support pillar 1, limiting lateral displacement to prevent microphone offset. In step S2012, the error microphone is fixed to the front end of the clamping support pillar 1 by threads, and the reference microphone is fixed to the outside of the inner connector 3 by an L-shaped bracket.

[0130] In this embodiment, spring 2 is a stainless steel helical spring, which is fitted onto the clamping support 1, with one end abutting the stepped surface of the inner connector 3 and the other end abutting the thrust plate 8. The vibration damping pad 5 is made of silicone rubber, which is fitted onto the front end of the clamping support 1, located between the error microphone and the thrust plate 8, and has a pre-tightened compression of 2mm.

[0131] As can be seen, the clamping strut 1 is rigidly connected to the thrust plate 8, and the preload of the spring 2 is transmitted to the clamping strut 1 through the thrust plate 8, making the vibration isolation pad 5 in close contact with the error microphone. The spring 2 absorbs low-frequency vibrations through elastic deformation, and the vibration isolation pad 5 absorbs high-frequency vibrations through damping characteristics, ensuring the capture of the original characteristics of external noise.

[0132] In step S2013, the vehicle vibration is transmitted to the outer connector 7 via the vehicle body. The outer connector 7 then transmits the vibration to the inner connector 3, which vibrates synchronously due to its rigid connection with the vehicle body. At this time, the clamping strut 1 is constrained by the spring 2, limiting its longitudinal displacement. The compression of the spring 2 varies with the vibration amplitude. Due to the damping properties of the silicone rubber, the vibration damping pad 5 converts the vibration energy into heat energy. The error microphone and the reference microphone move synchronously with the clamping strut 1, but because the vibration damping device suppresses high-frequency vibrations, the microphone displacement relative to the vehicle body is ≤0.2mm. In step S2014, when the cab is opened, noise signal acquisition is turned off in S102, but the microphone vibration damping device remains operational. The spring 2 maintains a 5N preload, the vibration damping pad 5 continuously clamps the error and reference microphones, and the thrust plate 8 is rigidly connected to the clamping strut 1, restricting the free movement of the microphones. If vibration occurs during vehicle operation, the spring 2 and the vibration damping pad 5 still provide vibration damping. In this way, the preload of spring 2 and the damping characteristics of vibration isolation pad 5 ensure that the microphone is protected when not in the acquisition state, avoiding mechanical damage.

[0133] In step S2015, the displacement sensor is installed between the inner connector 3 and the clamping support 1 to monitor the longitudinal displacement of the clamping support 1 in real time. The sensor signal is read, and when the displacement exceeds a threshold, an abnormality in the vibration damping device is determined, such as a broken spring or aging vibration isolation pad. A fault code is generated and sent to the instrument panel via the CAN bus. This enables visualization of the vibration damping device's status, allowing users to quickly determine whether the vibration damping function is normal through the instrument panel, improving the system's reliability and maintainability.

[0134] In one embodiment of the present invention, based on step S102, the following will provide a possible embodiment and its specific implementation will be described in a non-limiting manner. S102 further includes the following steps:

[0135] Step S2031: A damping ring is fitted on the outside of the spring. The damping ring is made of a high-molecular elastic material, wraps around the outer surface of the spring and contacts the inner groove of the outer connector to form a friction damping structure.

[0136] Step S2032: A multi-layer composite structure is set at the bottom of the vibration isolation pad, including an upper metal plate, a middle rubber layer and a lower metal plate. The metal plate and the rubber layer are bonded together by a vulcanization process to form a rigid-flexible composite vibration damping layer.

[0137] Step S2033: A corrugated buffer pad is provided between the contact surfaces of the clamping support and the vibration isolation pad. The corrugated buffer pad is formed by stamping a thin metal sheet and is embedded in the groove at the front end of the clamping support.

[0138] Step S2034: An arc-shaped groove is provided in the area where the bottom support surface of the thrust plate contacts the spring. The arc-shaped groove matches the compression direction of the spring so that the force on the spring is evenly distributed.

[0139] Step S2035: A limiting protrusion is provided on the outer edge of the vibration isolation pad. The limiting protrusion forms a sliding fit with the inner wall of the outer connector to limit the displacement of the vibration isolation pad in the lateral direction.

[0140] As can be seen, in step S2031, the damping ring wraps around the outer surface of the spring. When the spring is compressed or rebounds, the damping ring and the inner groove of the outer connector generate relative sliding friction, which consumes vibration energy through frictional resistance and improves the overall vibration reduction efficiency. In step S2032, the upper and lower metal plates are bonded together by a middle rubber layer, forming a rigid-flexible composite structure. When vibration is transmitted to the vibration isolation pad, the metal plate provides rigid support, and the rubber layer absorbs vibration energy through deformation. In step S2033, the corrugated buffer pad is embedded in the groove at the front end of the clamping column. When the clamping column pushes the vibration isolation pad, the corrugated buffer pad absorbs local impact force through its own corrugated deformation, avoiding direct hard contact. The deformation capability of the corrugated buffer pad can adapt to small displacement deviations during the clamping process, reducing vibration transmission caused by uneven clamping force, while protecting the surfaces of the clamping column and the vibration isolation pad from wear. In step S2034, the arc-shaped groove matches the compression direction of the spring, maximizing the contact area between the coils when the spring is under force, thus preventing localized stress concentration that could lead to spring fatigue and breakage. In step S2035, the limiting protrusion slides against the inner wall of the outer connector, restricting the lateral displacement of the vibration damping pad. When vehicle vibration causes lateral swaying of the vibration damping pad, the limiting protrusion contacts the inner wall of the outer connector, suppressing lateral movement through friction. The limiting protrusion structure prevents the vibration damping pad from loosening or shifting due to lateral vibration, ensuring that the clamping force between the clamping strut and the vibration damping pad always acts on the center of the mounting base of the error and reference microphone, improving clamping stability.

[0141] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0142] The following are embodiments of the microphone vibration reduction device provided in this disclosure. This device belongs to the same inventive concept as the active noise reduction method with dispersion suppression in the above embodiments. For details not described in detail in the embodiments of the microphone vibration reduction device, please refer to the embodiments of the active noise reduction method with dispersion suppression described above.

[0143] like Figures 2 to 3 As shown, the microphone vibration damping device includes an outer connector 7 and an inner connector 3; the inner connector 3 is disposed inside the outer connector 7. The outer connector 7 has multiple mounting bolt holes 6 for fastening the microphone vibration damping device to the vehicle body; the cross-section of the outer connector 7 and the cross-section of the inner connector 3 are both polygonal structures; multiple elastic components and multiple support pillars 4 are evenly distributed between the outer connector 7 and the inner connector 3 at intervals.

[0144] Multiple elastic components and multiple support pillars 4 are connected between the outer connector 7 and the inner connector 3; the inner connector 3 is provided with vibration isolation pads 5.

[0145] The elastic component includes: spring 2, clamping support 1 and thrust plate 8; one end of clamping support 1 is connected to vibration isolation pad 5 through inner connector 3, and the other end of clamping support 1 is fixedly connected to one side of thrust plate 8; one end of spring 2 is connected to the other side of thrust plate 8, and the other end of spring 2 is fixedly connected to the inner wall of outer connector 7.

[0146] It should be noted that the clamping strut connects the vibration damping pad and the thrust plate. Under spring compression, the rebound force pushes the thrust plate, and the clamping strut and thrust plate are rigidly connected. The thrust plate pushes the clamping strut, thus controlling the clamping error of the vibration damping pad and the reference microphone at the front end of the clamping strut. The spring provides thrust, pushing the thrust plate to complete the clamping error of the vibration damping pad and the reference microphone action. In addition to providing thrust, the spring also achieves primary vibration reduction, reducing vehicle body vibration transmitted to the error and reference microphone through the vibration damping device.

[0147] The inner connector restricts the clamping strut's degrees of freedom, ensuring it always moves longitudinally. The inner connector and the inner and outer connector struts are rigidly connected to guarantee normal operation. The inner and outer connectors mutually constrain each other, ensuring proper functioning. The vibration damping pad serves as a clamping error and reference microphone, reducing the impact of vehicle vibration and noise on the error and reference microphone. The thrust plate connects the spring and the clamping strut, effectively and evenly transmitting the spring force to the clamping strut, ensuring efficient operation of the device.

[0148] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An active noise reduction method with divergence suppression, characterized in that, The method is based on a microphone vibration damping device, which includes an outer connector (7) and an inner connector (3); the inner connector (3) is disposed inside the outer connector (7); and multiple elastic components and multiple support pillars (4) are connected between the outer connector (7) and the inner connector (3). The internal connector (3) is equipped with a vibration damping pad (5); The elastic components include: a spring (2), a clamping strut (1), and a thrust plate (8); One end of the clamping column (1) is connected to the vibration isolation pad (5) through the inner connector (3), and the other end of the clamping column (1) is fixedly connected to one side of the thrust plate (8); One end of the spring (2) is connected to the other side of the thrust plate (8), and the other end of the spring (2) is fixedly connected to the inner wall of the outer connector (7); The methods include: S101: Detects the airtightness of the vehicle's cab based on signals from door sensors, window sensors, and sunroof sensors; S102: When the cab is closed, noise signals inside the vehicle are collected through the error microphone and reference microphone installed by the microphone vibration damping device; when the cab is open, the collection of noise signals is turned off. S102 also includes the following steps: The microphone vibration damping device is installed on the inner side wall of the vehicle's cab. The inner connector is rigidly connected to the cab body through the mounting bolt holes of the outer connector to limit the freedom of the clamping strut. The error microphone and the reference microphone are fixed to the microphone vibration damping device, and the vibration isolation pad is clamped to the microphone by the pre-tightening spring. When the cab is sealed, noise signal acquisition is activated, and the microphone vibration damping device dampens vibration through springs and vibration isolation pads. When the cab is opened, noise signal acquisition is turned off, and the microphone damping device maintains spring preload to clamp the microphone. The longitudinal displacement of the clamping column is monitored by a displacement sensor, and a fault signal is sent to the instrument panel when the displacement exceeds a threshold. S103: When the cab is sealed, a secondary noise signal is generated based on the collected noise signal through an active noise reduction filter; S104: Play secondary noise signals through a speaker; S105: When the cab is opened, read the engine speed from the vehicle's CAN signal; S106: Generate a reference noise signal based on engine speed; S106 specifically includes the following methods: An engine speed reference noise signal mapping module is set in the vehicle's electronic control unit to pre-store the reference noise signal characteristic parameters corresponding to different engine speeds; The engine speed signal read in step S105 is obtained from the vehicle's CAN bus and transmitted to the engine speed reference noise signal mapping module. Based on the received engine speed signal, find the corresponding reference noise signal characteristic parameters; Based on the found characteristic parameters of the reference noise signal, a reference noise signal is generated, and the frequency and amplitude of the signal are adjusted according to the parameters using the principle of a signal generator. The generated reference noise signal is transmitted to the speaker through the audio output interface; S107: Play the reference noise signal through the speaker; S107 specifically includes the following methods: The digital reference noise signal is converted into multiple analog voltage signals using a multi-channel digital-to-analog converter; A differential amplifier is used to convert the voltage signal into a balanced audio signal, and a low-pass filter is used to eliminate high-frequency quantization noise. An audio power amplifier is used to amplify the balanced audio signal to drive the vehicle speaker system; The power amplifier chip junction temperature is monitored in real time by a temperature sensor, and the output power is reduced when the temperature exceeds the threshold. S108: Displays the cab sealing status and the operating status of the active noise reduction system on the instrument panel. The operating status is based on the noise signal acquisition and noise reduction signal playback.

2. The active noise reduction method with divergence suppression according to claim 1, characterized in that, S101 specifically includes the following methods: Connect the door sensor, window sensor, and sunroof sensor to the signal input interface of the vehicle body control module (BCM) via signal lines. An RC filter circuit is installed inside the Body Control Module (BCM). The input of the RC filter circuit is connected to the signal lines of each sensor to filter the raw electrical signals output by the sensors. The Body Control Module (BCM) reads sensor signals, converts the mechanical switch signals of the door sensors into 0-5V level signals, converts the Hall signals of the window sensors into pulse counting signals, and converts the photoelectric signals of the sunroof sensors into switch levels. The Body Control Module (BCM) presets the closing status thresholds for doors, windows, and sunroof: a door signal of 5V is considered closed, and 0V is considered open; a window pulse count reaching a preset value is considered closed, and not reaching it is considered open; a sunroof signal of 5V is considered closed, and 0V is considered open; when all doors, windows, and sunroofs are determined to be closed, a cab sealing status signal is generated; otherwise, a cab opening status signal is generated. The Body Control Module (BCM) sends signals indicating whether the cab is closed or open to the active noise cancellation system.

3. The active noise reduction method with divergence suppression according to claim 1, characterized in that, S102 specifically includes the following methods: The analog voltage signals from the error microphone and the reference microphone are acquired and converted into digital signals. The converted digital signal is then filtered. When the cab is open, a control signal is sent to the microphone preamplifier to cut off the microphone power supply circuit and stop signal acquisition. When the cab is sealed, an enable signal is sent to the microphone preamplifier to connect the microphone power supply circuit and start signal acquisition. The acquired and processed digital signal is transmitted to the active noise reduction system through the parallel interface of the digital signal processor.

4. The active noise reduction method with divergence suppression according to claim 1, characterized in that, S108 specifically includes the following methods: The status register stores the cab sealing status indicator and the active noise reduction system operation status indicator in real time. The instrument panel display controller reads status data from the status register and performs display data format conversion; The icon display unit displays the cab sealing status icon and the active noise reduction system operation status icon in a designated area of ​​the instrument panel; A multi-color LED driver circuit is used to control the display color and flashing frequency of the status indicator light.

5. The active noise reduction method with divergence suppression according to claim 1, characterized in that, S102 also includes the following steps: A damping ring is fitted on the outside of the spring. The damping ring is made of a high-molecular elastic material, wraps around the outer surface of the spring and contacts the inner groove of the outer connector to form a friction damping structure. A multi-layer composite structure is set at the bottom of the vibration isolation pad, including an upper metal plate, a middle rubber layer and a lower metal plate. The metal plate and the rubber layer are bonded together by a vulcanization process to form a composite vibration damping layer that combines rigidity and flexibility. A corrugated buffer pad is installed between the contact surfaces of the clamping column and the vibration isolation pad. The corrugated buffer pad is formed by stamping thin metal sheet and is embedded in the groove at the front end of the clamping column. An arc-shaped groove is provided in the area where the bottom support surface of the thrust plate contacts the spring. The arc-shaped groove matches the compression direction of the spring, so that the force on the spring is evenly distributed. A limiting protrusion is provided on the outer edge of the vibration isolation pad. The limiting protrusion forms a sliding fit with the inner wall of the outer connector to limit the displacement of the vibration isolation pad in the lateral direction.

6. The active noise reduction method with divergence suppression according to claim 1, characterized in that, The external connector (7) has multiple mounting bolt holes (6) for fastening the microphone damping device to the vehicle body; The cross-sections of the outer connector (7) and the inner connector (3) are both polygonal structures; Multiple elastic components and multiple support pillars (4) are evenly distributed at intervals between the outer connector (7) and the inner connector (3).

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