Vehicle-mounted IVI noise reduction system and method based on fan noise control

Abstract

The invention discloses a vehicle-mounted IVI noise reduction system and method based on fan noise control. The vehicle-mounted IVI noise reduction system comprises an MCU control module, a fan PWM control module, an SOC system processing module, a digital signal processing module, a digital power amplifier module, a fan module, a temperature sensor, a microphone and a loudspeaker. According to the method, a three-mode noise reduction mechanism is constructed, a fan speed regulation method based on temperature, noise and load ternary control is combined with a noise template matching algorithm for rotating speed prediction, and fan noise is eliminated through noise library reverse superposition; constructing a noise reduction system hardware architecture (temperature sensing, double microphones and DSP); and efficient noise reduction is realized through a noise feature library establishment and updating mechanism of a vehicle-mounted scene.

Description

Technical Field

[0001] This invention relates to the field of noise control technology for in-vehicle infotainment systems, and in particular to an in-vehicle IVI noise reduction system and method based on controlling fan noise. Background Technology

[0002] In-Vehicle Infotainment (IVI) is a comprehensive in-vehicle information processing system that uses a dedicated onboard central processing unit, based on the vehicle bus system and internet services. IVI can realize a range of applications including 3D navigation, real-time traffic information, IPTV, driver assistance, fault detection, vehicle information, vehicle control, mobile office, wireless communication, online entertainment functions, and TSP services, greatly improving the vehicle's level of electronic, networked, and intelligent capabilities.

[0003] The core challenges currently facing in-vehicle IVI systems are: 1) Heat dissipation requirements: High-performance processors require forced cooling by fans, but the high-speed operation of these fans generates a wide frequency range of noise (60-2000Hz). 2) Noise interference: Fan noise overlaps with the speech frequency range (300-3400Hz), reducing the accuracy of speech recognition. 3) Existing limitations: Traditional audio noise reduction only processes existing noise and cannot eliminate the noise source. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an in-vehicle IVI noise reduction system and method based on controlling fan noise. It optimizes the fan bracket and air duct structure to reduce vibration noise; by optimizing the fan speed, it reduces fan energy consumption and proposes a multimodal noise reduction mechanism to achieve efficient noise reduction.

[0005] The objective of this invention is achieved in one aspect as follows: an in-vehicle IVI noise reduction system based on controlling fan noise, comprising an MCU control module, a fan PWM control module, a SOC system processing module, a digital signal processing module, a digital power amplifier module, a fan module, a temperature sensor, a microphone, and a speaker;

[0006] The MCU control module is used to control the system startup and sleep. During startup, it initializes and configures the fan PWM control module, SOC system processing module and digital power amplifier module. After startup, it receives the speed data transmitted by the SOC system processing module, converts it into PWM and sends it to the fan PWM control module to control the fan module. At the same time, it monitors whether the speed is consistent with the setting based on the FG signal fed back by the fan module.

[0007] The fan PWM control module is used to convert the PWM signal into a voltage value;

[0008] The SOC system processing module is used to run the Android system, initialize the digital signal processing module, establish a fan noise feature library and noise reduction model based on the collected baseline data, calculate the optimal speed based on the temperature data sent by the temperature sensor, the noise data sent by the digital signal processing module and the system power consumption, and send it to the MCU control module; recognize voice commands based on the audio signal from the microphone sent by the digital signal processing module; and send multimedia audio signals to the digital signal processing module.

[0009] The digital signal processing module is used to collect the audio data sent by the fan module and send it to the SOC system processing module, filter out the audio from the speaker in the fan module, and send the received audio data from the SOC system processing module to the digital power amplifier module after processing.

[0010] The digital power amplifier module is used to amplify the audio signal sent by the digital signal processing module and send the amplified signal to the speaker;

[0011] The fan module is used to control the rotation speed according to the voltage value provided by the fan PWM control module;

[0012] The temperature sensor is used to collect temperature data and send it to the SOC system processing module.

[0013] The microphone is used to collect ambient noise and voice information and send it to the digital signal processing module.

[0014] The loudspeaker is used to convert the electrical signals sent by the digital power amplifier module into audio signals;

[0015] The MCU control module is electrically connected to the fan PWM control module, the SOC system processing module, and the digital power amplifier module; the digital signal processing module is electrically connected to the SOC system processing module and the digital power amplifier module; the fan PWM control module is electrically connected to the fan module; the SOC system processing module is electrically connected to the temperature sensor; the digital signal processing module is electrically connected to the microphone; and the digital power amplifier module is electrically connected to the speaker.

[0016] Furthermore, the fan module includes a housing, a heat sink, and a fan assembly; the housing is connected to the heat sink via riveting posts; the fan assembly is mounted on the side plate of the housing via a fan bracket; the heat sink is provided with multiple air duct structural components, and the edges of the air duct structural components are set with rounded corners or beveled corners.

[0017] Furthermore, the fan assembly includes a fan and a fan bracket. The fan is assembled with the fan bracket via a pre-compression spring on the bracket. Ribs are provided on both sides of the fan bracket, screw holes are provided on the top of the fan bracket, and bracket locking points are provided on the bottom of the fan bracket. The housing side plate is provided with a Z-direction fixing boss, guide limiting ribs, and housing locking holes. The fan assembly is assembled onto the housing side plate via the guide limiting ribs, and then pre-fixed to the housing side plate via the bracket locking points below the fan bracket and the locking holes on the housing side plate, and limited by the Z-direction fixing boss. Finally, it is fixed to the housing side plate with screws.

[0018] Furthermore, a fan inlet is provided on the side panel of the housing, and the fan inlet is 2mm away from the fan assembly.

[0019] Furthermore, the fan inlet is provided with a spoke structure, and the direction of the spoke structure is opposite to the direction of the fan blades.

[0020] Another aspect of the objective of this invention is achieved as follows: a method for noise reduction of an in-vehicle IVI based on controlling fan noise, comprising the following steps:

[0021] 1) Fan structure design: By designing the fan, fan bracket, and air duct structure, vibration and noise are reduced;

[0022] 2) Collect baseline data, and based on the collected baseline data, establish a fan noise feature library and a noise reduction model;

[0023] 3) When the system starts up, the MCU control module provides an initial PWM signal to the fan PWM control module. The fan PWM control module outputs a certain voltage to the fan module according to the PWM signal. The fan module adjusts its speed according to the voltage. After the fan module rotates, it feeds back the FG speed signal to the MCU control module.

[0024] 4) The microphone sends the noise signals collected from the fan module and the speaker to the digital signal processing module. The digital signal processing module amplifies the noise signals through the digital power amplifier module, filters them out by the speaker output section, and then sends them to the SOC system processing module.

[0025] 5) The temperature sensor collects the temperature of high-power devices in the system and sends it to the SOC system processing module;

[0026] 6) The SOC system processing module calculates the optimal speed based on noise, temperature, and load parameters using a noise reduction model, and sends the speed data to the MCU control module. The MCU control module converts the speed data into a PWM signal and sends it to the fan PWM control module. The fan PWM control module outputs a certain voltage to the fan module based on the PWM signal. After the fan module rotates, it feeds back the FG speed signal to the MCU control module.

[0027] 7) When voice wake-up occurs, the SOC system processing module calls the noise templates pre-stored in the noise feature library of the digital signal processing module based on the current fan speed and fan noise characteristics. It then combines the noise template matching algorithm based on speed prediction with the superimposed sound source with the opposite phase to the noise for filtering to eliminate fan noise.

[0028] Furthermore, step 1) specifically includes: selecting a silent bearing fan to reduce bearing friction and vibration; selecting an appropriate number of fan blades and the blade installation angle; making rounded and beveled transitions on the air duct structure of the fan's heat sink; ensuring an interference fit between the fan and the fan bracket to reduce noise generated by fan vibration; maintaining a certain distance between the fan and the air inlet of the casing; and ensuring that the direction of the fan inlet spokes is opposite to the direction of the fan blades to reduce air turbulence.

[0029] Furthermore, the baseline data collection mentioned in step 2) includes:

[0030] The fan noise spectrum at different speeds was measured in an anechoic chamber, and a speed-noise mapping matrix M was constructed. n×f ;

[0031] SOC temperature rise data at different rotation speeds and ambient temperatures were measured in a high and low temperature chamber, and a rotation speed-temperature mapping matrix M was constructed. n×T ;

[0032] SOC temperature rise data were measured under different ambient temperatures and load conditions in a high and low temperature chamber; a temperature-load mapping matrix M was constructed. T×P .

[0033] Furthermore, step 2) involves establishing a fan noise feature library based on the collected baseline data, which includes:

[0034] Fan noise feature library:

[0035] S(f) is the power spectral density function, representing the energy intensity of noise at frequency f. It describes the distribution of noise energy with frequency. In the fan noise model, S(f) helps the system identify which frequency points have the strongest noise, thus enabling the design of targeted filters for noise reduction.

[0036] A k It is the amplitude value of the k-th frequency component (such as the passing frequency of fan blades or harmonics). It represents the noise intensity at that frequency point, where k is the index (k = 1, 2, ..., N), and N is the total number of characteristic frequencies;

[0037] δ(ff k ) is the Dirac delta function, representing the frequency f. k The pulse at the location;

[0038] f k Here, k is the characteristic frequency, k is the index (k = 1, 2, ..., N), and N is the total number of characteristic frequencies; represents the Blade Pass Frequency (BPF), calculated using the following formula: Where B is the number of blades and RPM is the fan speed, revolutions per minute.

[0039] Furthermore, the noise reduction model described in step 2) is a three-modal noise reduction mechanism: dynamically adjusting the fan speed based on a temperature, noise, and load mapping function: n fan =f(T) cpu , Φ noise , α), where T cpu For processor temperature, Φ noise Let α be the noise energy and α be the system load factor.

[0040] The present invention, employing the above technical solutions, has the following advantages compared to existing technologies: By selecting a silent bearing fan, the present invention reduces bearing friction and vibration; by choosing an appropriate number of fan blades and their installation angle; by using rounded and beveled transitions in the air duct structure to reduce system impedance; by using an interference fit between the fan and the fan bracket to reduce noise generated by fan vibration; and by maintaining a certain distance between the fan and the air inlet of the casing to reduce airflow obstruction. Furthermore, the design of the fan inlet spokes is such that their direction is opposite to the direction of the fan blades, reducing airflow turbulence.

[0041] The method of this invention constructs a three-modal noise reduction mechanism, a fan speed regulation method based on temperature, noise and load ternary control, and combines a noise template matching algorithm based on speed prediction. It eliminates fan noise by inverse superposition of a noise library. It constructs a noise reduction system hardware architecture (temperature sensor + dual microphones + DSP). It achieves efficient noise reduction through a noise feature library establishment and update mechanism for vehicle scenarios. Attached Figure Description

[0042] Figure 1 System configuration block diagram of the present invention.

[0043] Figure 2 Initial workflow diagram of the present invention.

[0044] Figure 3 Normal operation flowchart of this invention.

[0045] Figure 4 A three-dimensional structural view of the fan module of this invention.

[0046] Figure 5 A schematic diagram of the housing and heat sink of the fan module of the present invention.

[0047] Figure 6A schematic diagram of the fan assembly structure in the fan module of this invention.

[0048] Figure 7 A schematic diagram of the fan assembly and housing side plate structure in this invention.

[0049] Figure 8 Side view of the fan module in this invention.

[0050] Figure 9 A schematic diagram of the spoke structure in the fan module of this invention.

[0051] The components include: 1. Housing, 1-1 Housing side plate, 1-1-1 Z-direction fixing boss, 1-1-2 Guide limiting rib, 1-1-3 Housing snap-fit ​​hole, 2. Heat sink, 2-1 Air duct structure; 3. Fan assembly, 3-1 Fan, 3-2 Fan bracket, 3-2-1 Preload spring, 3-2-2 Rib, 3-2-3 Screw hole, 3-2-4 Bracket snap-fit ​​point, 4. Fan air inlet, 4-1 Spoke structure, 5. Fan blade, 6. Riveting post. Detailed Implementation

[0052] like Figure 1 The vehicle IVI noise reduction system shown includes an MCU control module, a fan PWM control module, a SOC system processing module, a digital signal processing module, a digital power amplifier module, a fan module, a temperature sensor, a microphone, and a speaker.

[0053] The MCU control module is used to control the system startup and sleep. During startup, it initializes and configures the fan PWM control module, SOC system processing module and digital power amplifier module. After startup, it receives the speed data transmitted by the SOC system processing module, converts it into PWM and sends it to the fan PWM control module to control the fan module. At the same time, it monitors whether the speed is consistent with the setting based on the FG signal fed back by the fan module.

[0054] The fan PWM control module is used to convert PWM signals into voltage values;

[0055] The SOC system processing module is used to run the Android system, initialize the digital signal processing module, establish a fan noise feature library and noise reduction model based on the collected baseline data, calculate the optimal speed based on the temperature data sent by the temperature sensor, the noise data sent by the digital signal processing module and the system power consumption, and send it to the MCU control module; recognize voice commands based on the audio signal from the microphone sent by the digital signal processing module; and send multimedia audio signals to the digital signal processing module.

[0056] The digital signal processing module is used to collect the audio data sent by the fan module and send it to the SOC system processing module. It also filters out the audio from the speaker in the fan module and sends the received audio data from the SOC system processing module to the digital power amplifier module after processing.

[0057] The digital power amplifier module is used to amplify the audio signal sent by the digital signal processing module and send the amplified signal to the speaker;

[0058] The fan module is used to control the rotation speed based on the voltage value provided by the fan PWM control module;

[0059] The temperature sensor is used to collect temperature data and send it to the SOC system processing module;

[0060] The microphone is used to collect ambient noise and voice information and send it to the digital signal processing module;

[0061] The loudspeaker is used to convert the electrical signals sent by the digital power amplifier module into audio signals;

[0062] The MCU control module is electrically connected to the fan PWM control module, the SOC system processing module, and the digital power amplifier module; the digital signal processing module is electrically connected to the SOC system processing module and the digital power amplifier module; the fan PWM control module is electrically connected to the fan module; the SOC system processing module is electrically connected to the temperature sensor; the digital signal processing module is electrically connected to the microphone; and the digital power amplifier module is electrically connected to the speaker.

[0063] like Figure 4-5 As shown, the fan module includes a housing 1, a heat sink 2, and a fan assembly 3; the housing 1 is connected to the heat sink 2 by eight riveting posts; the fan assembly 3 is mounted on the side plate 1-1 of the housing by a fan bracket 3-2; the heat sink 2 is provided with multiple air duct structural components 2-1, and the edges of the air duct structural components 2-1 are set with rounded corners or beveled corners to reduce system impedance.

[0064] like Figure 6-7As shown, the fan assembly 3 includes a fan 3-1 and a fan bracket 3-2. The fan 3-1 is assembled with the fan bracket 3-2 via seven preload springs 3-2-1 on the bracket through an interference fit, ensuring that the fan is preloaded and fixed in the X / Y directions, reducing noise generated by fan vibration. Ribs 3-2-2 are provided on both sides of the fan bracket 3-2, screw holes 3-2-3 are provided on the top of the fan bracket 3-2, and bracket locking points 3-2-4 are provided on the bottom of the fan bracket 3-2. A Z-direction fixing boss 1-1-1 is provided on the side plate 1-1 of the housing. The fan assembly 3 is assembled onto the side plate 1-1 of the housing via the guide limiting rib 1-1-2, and then pre-fixed to the housing snap-fit ​​hole 1-1-3 on the side plate 1-1 via the bracket snap-fit ​​point 3-2-4 below the fan bracket 3-2. It is limited by four Z-direction fixing bosses 1-1-1. Finally, it is fixed to the side plate 1-1 of the housing with two screws, forming a triangular fixation with the lower bracket snap-fit ​​point 3-2-4, which strengthens the bracket fixation and reduces the risk of vibration and abnormal noise of the fan bracket 3-2.

[0065] like Figure 8-9 As shown, a fan inlet 4 is also provided on the side plate 1-1 of the housing. The fan inlet 4 is 2mm away from the fan assembly 3 to reduce airflow obstruction. A spoke structure 4-1 is provided on the fan inlet 4. The direction of the spoke structure 4 is opposite to the direction of the fan blades 5 to reduce airflow turbulence.

[0066] A noise reduction method for in-vehicle IVI based on controlling fan noise includes the following steps:

[0067] 1) Fan structure design: Vibration and noise are reduced through the design of the fan, fan bracket, and air duct structure;

[0068] Select a silent bearing fan to reduce bearing friction and vibration; choose an appropriate number of fan blades and blade installation angle, a 7-blade fan is used in this embodiment; make rounded and beveled corners on the air duct structure of the fan heat sink to reduce system impedance; the fan and fan bracket are interference-fitted to reduce noise generated by fan vibration; maintain a certain distance between the fan and the air inlet of the casing to reduce airflow obstruction; the direction of the fan inlet spoke structure is opposite to the direction of the fan blades to reduce gas turbulence.

[0069] 2) Collect baseline data, and based on the collected baseline data, establish a fan noise feature library and a noise reduction model;

[0070] The fan noise spectrum at different speeds was measured in an anechoic chamber, and a speed-noise mapping matrix M was constructed. n×f ;

[0071] SOC temperature rise data at different rotation speeds and ambient temperatures were measured in a high and low temperature chamber, and a rotation speed-temperature mapping matrix M was constructed.n×T ;

[0072] SOC temperature rise data were measured under different ambient temperatures and load conditions in a high and low temperature chamber; a temperature-load mapping matrix M was constructed. T×P .

[0073] Establish a fan noise feature library: Fan noise feature library:

[0074] S(f) is the power spectral density function, which represents the energy intensity of noise at frequency f. It describes the distribution of noise energy with frequency. In the fan noise model, S(f) helps the system identify which frequency points have the strongest noise, so as to design filters for targeted noise reduction.

[0075] A k It is the amplitude value of the k-th frequency component (such as the passing frequency of the fan blades or harmonics), which represents the noise intensity at that frequency point. k is the index (k = 1, 2, ..., N), and N is the total number of characteristic frequencies.

[0076] δ(ff k ) is the Dirac delta function, representing the frequency f. k The pulse at the location;

[0077] f k Here, k is the characteristic frequency, k is the index (k = 1, 2, ..., N), and N is the total number of characteristic frequencies; represents the Blade Pass Frequency (BPF), calculated using the following formula: Where B is the number of blades, RPM is the fan speed (revolutions per minute), and when k is 1, f1 is the fundamental frequency; when k is 2, f2 is the second harmonic.

[0078] The noise reduction model employs a three-modal noise reduction mechanism: dynamically adjusting the fan speed based on a mapping function of temperature, noise, and load. fan =f(T) cpu , Φ noise , α), where T cpu For processor temperature, Φ noise Where α is the noise energy and α is the system load factor;

[0079] like Figure 2 The workflow shown in step 3) is as follows: the fan speed is adjusted according to the voltage. The initial fan speed is set to 3400 rpm to ensure the heat dissipation requirements when the system starts up normally.

[0080] 3) When the system starts up, the MCU control module provides an initial PWM signal to the fan PWM control module. The fan PWM control module outputs a certain voltage to the fan module according to the PWM signal. The fan module adjusts its speed according to the voltage. After the fan module rotates, it feeds back the FG speed signal to the MCU control module.

[0081] like Figure 3 The workflow shown in steps 4, 5), 6), and 7);

[0082] 4) The microphone sends the noise signals collected from the fan module and the speaker to the digital signal processing module. The digital signal processing module amplifies the noise signals through the digital power amplifier module, filters them out by the speaker output section, and then sends them to the SOC system processing module.

[0083] 5) The temperature sensor collects the temperature of high-power devices in the system and sends it to the SOC system processing module;

[0084] 6) The SOC system processing module calculates the optimal speed based on noise, temperature, and load parameters using a noise reduction model, and sends the speed data to the MCU control module. The MCU control module converts the speed data into a PWM signal and sends it to the fan PWM control module. The fan PWM control module outputs a certain voltage to the fan module based on the PWM signal. After the fan module rotates, it feeds back the FG speed signal to the MCU control module.

[0085] 7) When voice wake-up occurs, the SOC system processing module calls the noise templates pre-stored in the noise feature library of the digital signal processing module according to the current fan speed and fan noise characteristics. In this embodiment, the noise template matching algorithm is an adaptive filtering algorithm, which filters the fan noise by superimposing sound sources with opposite phase to the noise.

[0086] This invention provides an in-vehicle IVI noise reduction system and method based on controlling fan noise. The method involves selecting a fan with silent bearings to reduce bearing friction and vibration; choosing an appropriate number of fan blades and their installation angle; using rounded and beveled corners in the air duct structure to reduce system impedance; using an interference fit between the fan and fan bracket to reduce noise generated by fan vibration; and maintaining a certain distance between the fan and the air inlet of the casing to reduce airflow obstruction. The design of the fan inlet spokes is opposite to the direction of the fan blades to reduce airflow turbulence. A three-modal noise reduction mechanism is constructed, based on a fan speed control method using temperature, noise, and load as three dimensions, combined with a noise template matching algorithm based on speed prediction, and using reverse superposition of a noise database to eliminate fan noise. A noise reduction system hardware architecture (temperature sensor + dual microphones + DSP) is constructed; and an efficient noise reduction is achieved through a noise feature library establishment and update mechanism for in-vehicle scenarios.

[0087] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. A vehicle-mounted IVI noise reduction system based on controlling fan noise, characterized in that, It includes an MCU control module, a fan PWM control module, a SOC system processing module, a digital signal processing module, a digital power amplifier module, a fan module, a temperature sensor, a microphone, and a speaker; The MCU control module is used to control the system startup and sleep. During startup, it initializes and configures the fan PWM control module, SOC system processing module and digital power amplifier module. After startup, it receives the speed data transmitted by the SOC system processing module, converts it into PWM and sends it to the fan PWM control module to control the fan module. At the same time, it monitors whether the speed is consistent with the setting based on the FG signal fed back by the fan module. The fan PWM control module is used to convert the PWM signal into a voltage value; The SOC system processing module is used to run the Android system, initialize the digital signal processing module, establish a fan noise feature library and noise reduction model based on the collected baseline data, calculate the optimal speed based on the temperature data sent by the temperature sensor, the noise data sent by the digital signal processing module and the system power consumption, and send it to the MCU control module; recognize voice commands based on the audio signal from the microphone sent by the digital signal processing module; and send multimedia audio signals to the digital signal processing module. The digital signal processing module is used to collect the audio data sent by the fan module and send it to the SOC system processing module, filter out the audio from the speaker in the fan module, and send the received audio data from the SOC system processing module to the digital power amplifier module after processing. The digital power amplifier module is used to amplify the audio signal sent by the digital signal processing module and send the amplified signal to the speaker; The fan module is used to control the rotation speed according to the voltage value provided by the fan PWM control module; The temperature sensor is used to collect temperature data and send it to the SOC system processing module. The microphone is used to collect ambient noise and voice information and send it to the digital signal processing module. The loudspeaker is used to convert the electrical signals sent by the digital power amplifier module into audio signals; The MCU control module is electrically connected to the fan PWM control module, the SOC system processing module, and the digital power amplifier module; the digital signal processing module is electrically connected to the SOC system processing module and the digital power amplifier module; the fan PWM control module is electrically connected to the fan module; the SOC system processing module is electrically connected to the temperature sensor; the digital signal processing module is electrically connected to the microphone; and the digital power amplifier module is electrically connected to the speaker.

2. The vehicle-mounted IVI noise reduction system based on controlling fan noise according to claim 1, characterized in that, The fan module includes a housing, a heat sink, and a fan assembly; the housing is connected to the heat sink via riveting posts; the fan assembly is mounted on the side plate of the housing via a fan bracket; the heat sink is provided with multiple air duct structural components, and the edges of the air duct structural components are set with rounded or beveled corners.

3. The vehicle-mounted IVI noise reduction system based on controlling fan noise according to claim 2, characterized in that, The fan assembly includes a fan and a fan bracket. The fan is assembled with the fan bracket via a pre-compression spring on the bracket. Ribs are provided on both sides of the fan bracket, screw holes are provided on the top of the fan bracket, and bracket locking points are provided on the bottom of the fan bracket. The side plate of the housing is provided with a Z-direction fixing boss, guide limiting ribs, and housing locking holes. The fan assembly is assembled onto the side plate of the housing via the guide limiting ribs, and then pre-fixed by the bracket locking points below the fan bracket and the locking holes on the side plate of the housing, and limited by the Z-direction fixing boss. Finally, it is fixed to the side plate of the housing with screws.

4. The vehicle-mounted IVI noise reduction system based on controlling fan noise according to claim 3, characterized in that, A fan inlet is provided on the side plate of the housing, and the fan inlet is 2mm away from the fan assembly.

5. A vehicle-mounted IVI noise reduction system based on controlling fan noise according to claim 4, characterized in that, The fan inlet is provided with a spoke structure, and the direction of the spoke structure is opposite to the direction of the fan blades.

6. A method for noise reduction in vehicle-mounted IVI based on controlling fan noise, characterized in that, Includes the following steps: 1) Fan structure design: Vibration and noise are reduced through the design of the fan, fan bracket, and air duct structure; 2) Collect baseline data, and based on the collected baseline data, establish a fan noise feature library and a noise reduction model; 3) When the system starts up, the MCU control module provides an initial PWM signal to the fan PWM control module. The fan PWM control module outputs a certain voltage to the fan module according to the PWM signal. The fan module adjusts its speed according to the voltage. After the fan module rotates, it feeds back the FG speed signal to the MCU control module. 4) The microphone sends the noise signals collected from the fan module and the speaker to the digital signal processing module. The digital signal processing module amplifies the noise signals through the digital power amplifier module, filters them out by the speaker output section, and then sends them to the SOC system processing module. 5) The temperature sensor collects the temperature of high-power devices in the system and sends it to the SOC system processing module; 6) The SOC system processing module calculates the optimal speed based on noise, temperature, and load parameters using a noise reduction model, and sends the speed data to the MCU control module. The MCU control module converts the speed data into a PWM signal and sends it to the fan PWM control module. The fan PWM control module outputs a certain voltage to the fan module based on the PWM signal. After the fan module rotates, it feeds back the FG speed signal to the MCU control module. 7) When voice wake-up occurs, the SOC system processing module calls the noise templates pre-stored in the noise feature library of the digital signal processing module based on the current fan speed and fan noise characteristics. It then combines the noise template matching algorithm based on speed prediction with the superimposed sound source with the opposite phase to the noise for filtering to eliminate fan noise.

7. A method for reducing noise in a vehicle IVI system based on controlling fan noise according to claim 6, characterized in that, Step 1) specifically includes: selecting a silent bearing fan to reduce bearing friction and vibration; selecting an appropriate number of fan blades and the blade installation angle; making rounded and beveled transitions on the air duct structure of the fan's heat sink; ensuring an interference fit between the fan and the fan bracket to reduce noise generated by fan vibration; maintaining a certain distance between the fan and the air inlet of the casing; and ensuring that the direction of the fan inlet spokes is opposite to the direction of the fan blades to reduce air turbulence.

8. A method for reducing noise in a vehicle IVI system based on controlling fan noise according to claim 6, characterized in that, The baseline data collected in step 2) includes: The fan noise spectrum at different speeds was measured in an anechoic chamber, and a speed-noise mapping matrix M was constructed. n×f ; SOC temperature rise data at different rotation speeds and ambient temperatures were measured in a high and low temperature chamber, and a rotation speed-temperature mapping matrix M was constructed. n×T ; SOC temperature rise data were measured under different ambient temperatures and load conditions in a high and low temperature chamber; a temperature-load mapping matrix M was constructed. T×P .

9. A method for reducing noise in an in-vehicle IVI based on controlling fan noise according to claim 6, characterized in that, Step 2) describes establishing a fan noise feature library based on the collected baseline data, which includes: Fan noise feature library: S(f) is the power spectral density function, representing the energy intensity of noise at frequency f. It describes the distribution of noise energy with frequency; A k It is the amplitude value of the k-th frequency component, representing the noise intensity at that frequency point, where k is the index (k = 1, 2, ..., N), and N is the total number of characteristic frequencies; δ(ff) k ) is the Dirac delta function, representing the frequency f. k The pulse at the location; f k It is the characteristic frequency, k is the index k = 1, 2, ..., N, and N is the total number of characteristic frequencies, representing the blade passage frequency BPF, calculated using the following formula: Where B is the number of blades and RPM is the fan speed, revolutions per minute.

10. A method for reducing noise in an in-vehicle IVI system based on controlling fan noise according to claim 6, characterized in that, The noise reduction model described in step 2) is a three-modal noise reduction mechanism: dynamically adjusting the fan speed based on a temperature, noise, and load mapping function: n fan =f(T) cpu ,Φ noise ,α), where T cpu For processor temperature, Φ noise Let α be the noise energy and α be the system load factor.

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