Automobile seat with active and passive noise reduction air bag and noise reduction method thereof

Abstract

The application discloses a car seat with active and passive noise reduction air bags and a noise reduction method thereof, and relates to the technical field of car seat noise reduction. The seat comprises a seat body, a Helmholtz resonance air bag assembly, an active loudspeaker, and an active noise reduction control system. The air bag is divided into a main air bag and an auxiliary air bag by a flexible diaphragm. The main air bag supports vibration reduction, and the auxiliary air bag constitutes a Helmholtz resonance cavity for passive noise reduction. The active loudspeaker is arranged in the main air bag and cooperates with the control system to realize active noise reduction. The neck opening and the volume of the auxiliary air bag are adjustable, and the resonance frequency is 20-100 Hz. The noise reduction method comprises noise spectrum analysis, adaptive active noise reduction, resonance frequency adjustment, and effect closed-loop optimization, supports passive and hybrid working modes, and multiple air bags can be coordinated in a master-slave mode. The application integrates active and passive noise reduction, has compact structure, strong adaptability, and excellent noise reduction effect, effectively suppresses low-frequency noise of a car, and improves the quietness of the car.

Description

Technical Field

[0001] This invention relates to the field of automotive seat noise reduction technology, specifically to an automotive seat with both active and passive noise reduction airbags and its noise reduction method. Background Technology

[0002] During vehicle operation, various noises are generated in the cabin, including engine noise, road noise, and wind noise. Low-frequency noise accounts for a high proportion, has strong penetrating power, and is difficult to attenuate. Long-term exposure can easily cause fatigue and irritability for drivers and passengers, reducing ride comfort and driving safety. Traditional car seat noise reduction relies heavily on passive vibration damping structures, such as foam, rubber pads, and springs, which are effective at suppressing mid-to-high frequency noise, but have limited ability to reduce low-frequency noise in the 20-100Hz range, making it difficult to meet the quietness requirements of high-end models.

[0003] Existing air-suspension seats only offer height adjustment and vibration damping, failing to fully utilize the acoustic characteristics of the airbag cavity. Some passive noise reduction structures employ Helmholtz resonators, but their fixed resonant frequencies cannot adapt to changes in the noise spectrum under different vehicle speeds and road conditions. Active noise reduction technologies are mostly applied to the entire vehicle cabin, not integrated with the seat airbag, resulting in complex structures, large space requirements, high costs, and insufficient noise reduction targeting. Furthermore, existing devices often employ only active or passive noise reduction modes without forming a synergistic mechanism, limiting noise reduction bandwidth and effectiveness. Some structures have fixed neck opening parameters and non-adjustable airbag volume, resulting in a narrow resonant frequency adjustment range and difficulty in tracking dynamic noise frequencies. The control system lacks real-time noise analysis, adaptive resonant frequency adjustment, and closed-loop optimization of noise reduction effects, failing to maintain optimal noise reduction performance continuously.

[0004] Therefore, there is an urgent need to develop a device and method that integrates passive noise reduction with adaptive active noise reduction of Helmholtz resonance, has a compact structure, adjustable resonant frequency, is suitable for automotive seat installation, and can effectively suppress low-frequency noise, so as to solve the defects of existing technologies such as narrow noise reduction frequency band, poor adaptability, low integration and poor effect. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a car seat with both active and passive noise-reducing airbags and a noise reduction method thereof, solving the following technical problems: Traditional passive noise cancellation in seats is ineffective at suppressing low-frequency noise. The Helmholtz resonator has a fixed resonant frequency, which cannot adapt to the dynamic noise spectrum. Active noise cancellation is not integrated with the seat airbag, resulting in a complex structure, large space occupation, and low acoustic coupling efficiency. The active and passive noise cancellation modes do not work together, resulting in a narrow noise reduction bandwidth and limited effect. The neck opening parameters and airbag volume are not adjustable, resulting in a narrow resonant frequency adjustment range and an inability to track the main noise frequencies. The control system lacks a closed-loop optimization mechanism, leading to poor stability and weak adaptive capability in noise reduction.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a car seat with both active and passive noise-canceling airbags, comprising a seat body, a Helmholtz resonant airbag assembly, an active speaker, and an active noise-canceling control system; the Helmholtz resonant airbag assembly is composed of a seat air suspension airbag, with an internal flexible diaphragm separating it into a completely enclosed main airbag and a secondary airbag; a neck opening is provided on the wall of the secondary airbag, communicating with the internal cavity of the secondary airbag to form a Helmholtz resonator neck structure; the active speaker is fixedly installed inside the main airbag, with its diaphragm facing the internal cavity of the main airbag; the active noise-canceling control system includes a reference microphone, an error microphone, an adaptive filter, and a power amplifier; the reference microphone collects ambient noise signals from the cockpit, and the error microphone collects residual noise signals after noise reduction; the adaptive filter outputs an anti-phase sound wave control signal based on the reference signal and the error signal, and the power amplifier drives the active speaker to emit sound; the neck opening is provided with a parameter adjustment mechanism, and its cross-sectional area and length are adjustable; the volume of the secondary airbag can be adjusted within the range of 1-5L, making the Helmholtz resonant frequency adjustable within the range of 20-100Hz.

[0007] Furthermore, the geometric parameters of the neck opening satisfy the Helmholtz resonance frequency formula: Where f0 is the resonant frequency, c is the speed of sound, S is the cross-sectional area of ​​the neck, V is the volume of the auxiliary airbag, L is the neck length, and d is the diameter of the neck opening.

[0008] Furthermore, the diameter of the neck opening is 8-50mm, the neck length is 10-60mm, and the connection between the neck opening and the auxiliary airbag cavity adopts a rounded transition structure.

[0009] Furthermore, the active speaker is an ultra-thin woofer with a frequency response range of 20–1000Hz, and can be installed at any of the following locations: bottom, side, or top of the main airbag.

[0010] Furthermore, multiple airbag components are provided, which are respectively arranged inside the seat cushion, backrest, and headrest, and the multiple airbags adopt a master-slave cooperative control strategy.

[0011] A noise reduction method for car seats that combine active and passive noise-reducing airbags includes the following steps: Step 1: Calculate the target resonance frequency based on the main low-frequency noise frequency of the vehicle, and adjust the volume of the auxiliary airbag and the neck opening parameters to match the Helmholtz resonance frequency with the target frequency to achieve passive noise reduction. Step 2: Collect cockpit ambient noise through a reference microphone, perform real-time spectrum analysis, and identify the main low-frequency noise components; Step 3: Generate an anti-phase sound wave signal based on the low-frequency noise frequency components, and drive the active loudspeaker to generate same-frequency anti-phase sound waves in the airbag cavity to cancel out the noise. Step 4: Monitor residual noise using an error microphone; Step 5: The adaptive filter uses the FXLMS adaptive filtering algorithm to dynamically adjust the filter parameters based on the reference signal and error signal, continuously optimize the noise reduction performance, and achieve closed-loop optimization of the noise reduction effect.

[0012] Furthermore, the FXLMS adaptive filtering algorithm includes: initializing the adaptive filter coefficients W(n); acquiring the reference signal x(n) and the error signal e(n); calculating the filter output y(n) = W(n) × x(n); driving the active speaker to emit sound; updating the filter coefficients W(n+1) = W(n) + μ × e(n) × x'(n), where μ is the adaptive step size and x'(n) is the reference signal after filtering through the secondary path; and repeating the process cyclically to achieve adaptive noise reduction.

[0013] Furthermore, noise reduction methods include passive noise reduction and active noise reduction: passive noise reduction only uses the main and auxiliary airbags to passively absorb sound and reduce noise; active noise reduction uses anti-phase sound waves to reduce noise and uses the main airbag to amplify the noise reduction frequency to improve the noise reduction effect.

[0014] Furthermore, when multiple noise-reducing airbags are used, the main airbag adjusts the out-of-phase sound wave signal output of the speaker according to the main noise frequency, and the airbags are synchronized with the main airbag to form a distributed noise reduction array, thereby expanding the effective noise reduction space range.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides an integrated active and passive noise reduction system for a car seat that combines active and passive noise reduction airbags. The passive Helmholtz resonance effectively suppresses the target low-frequency noise, while the active anti-phase sound wave broadens the noise reduction frequency band and improves dynamic adaptability, thus achieving excellent noise reduction across the entire frequency band. (2) In this invention, the airbag reuse seat air suspension structure does not require additional major modifications, and has a compact structure, high integration, excellent space utilization and low cost. (3) The car seat in the invention has adjustable neck opening parameters and auxiliary airbag volume, and the resonant frequency is adjustable from 20 to 100 Hz to adapt to different noise spectrums under different working conditions. (4) The active speaker of the car seat in the invention is placed in the sealed main airbag, which improves the acoustic coupling efficiency and enhances the active noise reduction effect. The ultra-thin design does not affect the comfort of the seat. (5) In the noise reduction method of the car seat in the invention, the FXLMS adaptive algorithm is combined with closed-loop optimization to adjust the parameters in real time, resulting in stable noise reduction effect and strong adaptive capability. (6) The multi-airbag distributed array and master-slave collaborative control in the invention expand the effective noise reduction space, cover the main ear area of ​​the occupant, and improve the overall quietness. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] A car seat that combines active and passive noise reduction airbags includes a seat body, a Helmholtz resonant airbag assembly, an active speaker, and an active noise reduction control system. The Helmholtz resonant airbag assembly is installed inside the seat body and consists of air suspension airbags. It has a flexible diaphragm inside, which separates the main airbag into a completely sealed main airbag and a secondary airbag that serves as the Helmholtz resonant cavity. The main airbag is connected to the seat height adjustment mechanism to provide support and passive vibration damping. The secondary airbag wall has a neck opening that communicates with the internal cavity to form the neck structure of the Helmholtz resonator. The active speaker is an ultra-thin woofer, fixed inside the main airbag, with the diaphragm facing the main airbag cavity, forming an acoustic coupling system with the airbag wall; The active noise cancellation control system includes a reference microphone, an error microphone, an adaptive filter, and a power amplifier. The reference microphone is positioned near the noise source to collect ambient noise signals. The error microphone is positioned in the area corresponding to the occupant's ear to collect residual noise signals after noise cancellation. The adaptive filter connects the reference microphone and the error microphone, receives signals, and calculates the anti-phase sound wave control signal. The power amplifier's input is connected to the adaptive filter, and its output is connected to the active speaker to drive the speaker to emit sound. The neck opening is equipped with a parameter adjustment mechanism, and its cross-sectional area and length are adjustable; the volume of the auxiliary airbag is adjustable within the range of 1-5L, and the resonant frequency can be adjusted from 20 to 100Hz. The geometric parameters of the neck opening satisfy the Helmholtz resonance frequency formula: In the formula: f0 is the resonant frequency, c is the speed of sound, S is the cross-sectional area of ​​the neck, V is the volume of the air bladder, L is the length of the neck, and d is the diameter of the neck opening; The neck opening diameter is 8-50mm, the neck length is 10-60mm, and the connection is rounded; the active speaker frequency response is 20-1000Hz, and it is installed at the bottom, side or top of the main airbag. The Helmholtz resonant airbag assembly consists of multiple units, distributed inside the seat cushion, backrest, and headrest. It employs master-slave collaborative control, with the master airbag adjusting the resonant frequency and the slave airbags synchronizing the phase, forming a distributed noise reduction array.

[0018] A method for noise reduction in a car seat that combines active and passive noise reduction airbags includes the following steps: Step 1: Determine the parameters of the auxiliary airbag cavity Calculate the target resonance frequency based on the vehicle's main low-frequency noise frequency, and adjust the auxiliary airbag volume and neck opening parameters to match the Helmholtz resonance frequency with the target frequency. Step 2: Real-time noise acquisition and spectrum analysis Reference microphones collect ambient noise from the cockpit and transmit it to the active noise cancellation control system for real-time spectrum analysis to identify the main noise frequency components in the 20-1000Hz range; Step 3: Active noise reduction, outputting sound waves of the same frequency but opposite phase. The active noise reduction control system automatically generates a sound wave signal with the same frequency but opposite phase based on the collected noise frequency, and drives the active speaker to output the signal inside the airbag cavity. Step 4: Acquire error signals Residual noise is monitored in real time via an error microphone and transmitted to an adaptive filter; Step 5: Closed-loop optimization of noise reduction effect The adaptive filter dynamically adjusts the filter parameters based on the reference signal and the error signal to continuously optimize the noise reduction performance and achieve closed-loop optimization of the noise reduction effect. The adaptive filter uses the FXLMS algorithm to initialize the filter coefficients W(n); acquire the reference signal x(n) and the error signal e(n); calculate the filter output y(n) = W(n) × x(n); drive the active speaker to emit sound; update the filter coefficients W(n+1) = W(n) + μ × e(n) × x'(n), where μ is the adaptive step size and x'(n) is the reference signal after filtering through the secondary path; and execute the algorithm in a loop to achieve adaptive noise reduction.

[0019] The hybrid noise reduction method includes passive noise reduction and active noise reduction: the passive noise reduction method only uses the main and auxiliary airbags to passively absorb sound and reduce noise; the active noise reduction method uses anti-phase sound waves to reduce noise and uses the main airbag to amplify the noise reduction frequency to improve the noise reduction effect; when multiple airbags are working, master-slave collaborative control is adopted to expand the noise reduction space range.

[0020] The present invention will be further described in detail below with reference to specific embodiments.

[0021] Example 1 A car seat that combines active and passive noise reduction airbags includes a seat body, a Helmholtz resonant airbag assembly, an active speaker, and an active noise reduction control system. The Helmholtz resonant airbag assembly is installed inside the seat cushion and consists of an air suspension airbag made of TPU flexible material. It has a 0.3mm thick flexible diaphragm inside, which separates the main airbag and the auxiliary airbag into a completely sealed main airbag. The auxiliary airbag has a Helmholtz resonant cavity structure. The volume of the auxiliary airbag is controlled at 1.5L according to the noise frequency. A circular neck opening with a diameter of 8.5mm and a length of 40mm is opened on the side wall. The connection is rounded and the resonant frequency covers 30-100Hz. Helmholtz resonance frequency formula: In the formula: c=343m / s, V=1.5L, L=40mm, d=8.5mm, the calculated f0≈49Hz, which is suitable for common road surface low-frequency noise; The main airbag has a volume of 2.5L and is connected to the seat height adjustment mechanism to support the seat and passively dampen vibrations. The active speaker is an ultra-thin woofer with a thickness of 6mm and a frequency response of 20-1000Hz. It is fixed in the center of the bottom of the main airbag with the diaphragm facing upwards towards the cavity, forming an acoustic coupling system with the airbag wall. The active noise cancellation control system includes a reference microphone, an error microphone, a digital adaptive filter, and a power amplifier. The reference microphone is located on the top outer side of the seat back to collect ambient noise. The error microphone is located on both sides of the headrest at the corresponding positions of the occupant's ears to collect residual noise. The adaptive filter uses a 32-bit floating-point DSP chip to run the FXLMS algorithm and calculate the inverted sound wave signal. The power amplifier has a gain of 30dB and drives the active speaker.

[0022] Example 2 A method for noise reduction in a car seat that combines active and passive noise reduction airbags includes: Step 1: Determine the parameters of the auxiliary airbag cavity The target resonant frequency is set to 55Hz. Substituting these values ​​into the formula, we get V=2.0L, L=30mm, and d=10mm. Step 2: Real-time noise acquisition and spectrum analysis While the vehicle is in motion, a reference microphone collects cabin noise at a sampling rate of 10kHz and transmits it to the DSP chip; the spectrum is analyzed in real time through FFT transformation, and the main noise frequencies are identified as 20-1000Hz. Step 3: Active noise reduction, outputting sound waves of the same frequency but opposite phase. The active noise cancellation control system automatically generates a same-frequency, opposite-phase sound wave signal based on the collected noise frequency, with a frequency range of 50-1000Hz. The signal is then amplified to drive the speaker inside the airbag cavity to generate an opposite-phase sound wave that is opposite in phase and similar in amplitude to the original noise, thus achieving cancellation. Step 4: Acquire error signals Residual noise is monitored in real time via an error microphone and transmitted to an adaptive filter; Step 5: Closed-loop optimization of noise reduction effect The adaptive filter uses the FXLMS algorithm, initializes the filter coefficients W(0)=0; acquires the reference signal x(n) and error signal e(n) in real time; calculates the filter output y(n)=W(n)×x(n); the adaptive filter dynamically adjusts the filter parameters, continuously optimizes the noise reduction performance, and achieves closed-loop optimization of the noise reduction effect. In the active-passive hybrid noise cancellation mode, the active speakers enhance the noise cancellation effect, reducing noise by 15-25dB, significantly improving driving comfort.

Claims

1. A car seat that integrates both active and passive noise-reducing airbags, characterized in that, The system includes a seat body, a Helmholtz resonant airbag assembly, an active speaker, and an active noise cancellation control system. The Helmholtz resonant airbag assembly consists of a seat air suspension airbag with an internal flexible diaphragm that separates it into a completely enclosed main airbag and a secondary airbag. The secondary airbag has a neck opening that communicates with the internal cavity of the secondary airbag to form the neck structure of the Helmholtz resonator. The active speaker is fixedly installed inside the main airbag with its diaphragm facing the internal cavity of the main airbag. The active noise cancellation control system includes a reference microphone, an error microphone, an adaptive filter, and a power amplifier. The reference microphone collects ambient noise signals from the cockpit, and the error microphone collects residual noise signals after noise reduction. The adaptive filter outputs an anti-phase acoustic wave control signal based on the reference signal and the error signal, and the power amplifier drives the active speaker to emit sound. The neck opening is equipped with a parameter adjustment mechanism, and its cross-sectional area and length are adjustable. The volume of the auxiliary airbag can be adjusted within the range of 1-5L, so that the Helmholtz resonance frequency is adjustable within the range of 20-100Hz.

2. A car seat with both active and passive noise-reducing airbags as described in claim 1, characterized in that: The geometric parameters of the neck opening satisfy the Helmholtz resonance frequency formula: Where f0 is the resonant frequency, c is the speed of sound, S is the cross-sectional area of ​​the neck, V is the volume of the auxiliary airbag, L is the neck length, and d is the diameter of the neck opening.

3. A car seat with both active and passive noise-reducing airbags as described in claim 1, characterized in that: The diameter of the neck opening is 8-50mm, the length of the neck is 10-60mm, and the connection between the neck opening and the auxiliary airbag cavity adopts a rounded transition structure.

4. A car seat with both active and passive noise-reducing airbags as described in claim 1, characterized in that: The active speaker is an ultra-thin woofer with a frequency response range of 20–1000Hz, and can be installed at any of the following locations: the bottom, side, or top of the main airbag.

5. A car seat with both active and passive noise-reducing airbags as described in claim 1, characterized in that: The Helmholtz resonance airbag assembly consists of multiple units, which are respectively arranged inside the seat cushion, backrest, and headrest. The multiple airbags adopt a master-slave cooperative control strategy.

6. A noise reduction method for a car seat with both active and passive noise-reducing airbags as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Calculate the target resonance frequency based on the main low-frequency noise frequency of the vehicle, and adjust the volume of the auxiliary airbag and the neck opening parameters to match the Helmholtz resonance frequency with the target frequency to achieve passive noise reduction. Step 2: Collect cockpit ambient noise through a reference microphone, perform real-time spectrum analysis, and identify the main low-frequency noise components; Step 3: Generate an anti-phase sound wave signal based on the low-frequency noise frequency components, and drive the active loudspeaker to generate same-frequency anti-phase sound waves in the airbag cavity to cancel out the noise. Step 4: Monitor residual noise using an error microphone; Step 5: The adaptive filter uses the FXLMS adaptive filtering algorithm to dynamically adjust the filter parameters based on the reference signal and error signal, continuously optimize the noise reduction performance, and achieve closed-loop optimization of the noise reduction effect.

7. A noise reduction method for a car seat with both active and passive noise-reducing airbags according to claim 6, characterized in that: The FXLMS adaptive filtering algorithm includes: initializing the adaptive filter coefficients W(n); acquiring the reference signal x(n) and the error signal e(n); calculating the filter output y(n) = W(n) × x(n); driving the active speaker to emit sound; updating the filter coefficients W(n+1) = W(n) + μ × e(n) × x'(n), where μ is the adaptive step size and x'(n) is the reference signal after filtering through the secondary path; and repeating the process to achieve adaptive noise reduction.

8. A car seat with both active and passive noise-reducing airbags according to claim 6, characterized in that: The noise reduction method includes passive noise reduction and active noise reduction: the passive noise reduction method only uses the main and auxiliary airbags to passively absorb sound and reduce noise. The active noise cancellation method uses anti-phase sound waves for noise reduction and uses the main airbag to amplify the noise reduction frequency, thereby improving the noise reduction effect; passive noise cancellation works in conjunction with active noise cancellation.

9. A car seat with both active and passive noise-reducing airbags according to claim 6, characterized in that: When multiple noise-reducing airbags are used, the main airbag adjusts the out-of-phase sound wave signal output of the speaker according to the main noise frequency. The airbags are synchronized with the main airbag to form a distributed noise reduction array, thereby expanding the effective noise reduction space.

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