A sound collector and diagnostic method for SCR system fault diagnosis

Abstract

This invention relates to the field of acoustic signal analysis technology, specifically to a sound collector and diagnostic method for SCR system fault diagnosis. It includes multiple directional microphone arrays arranged in a circular pattern on the outer ring of an elastic clamp. The elastic clamp is fitted onto the tube at the end of the jet valve. The directional microphone arrays are inserted into a mounting base, which is slidably connected to the outer ring of the elastic clamp. The mounting base has slots on its surface, and clamping blocks are inserted into the side walls of the slots. The advantages are: the use of an elastic clamp fitted onto the tube at the end of the jet valve allows the clamp to adapt to tubes of different sizes, simplifying the installation process. Furthermore, the rubber gaskets clamping the clamp between the clamp and the tube prevent loosening of the clamp and effectively reduce vibrations transmitted through the tube, improving the stability and accuracy of sound collection.

Description

Technical Field

[0001] This invention relates to the field of acoustic signal analysis technology, specifically to a sound collector and diagnostic method for SCR system fault diagnosis. Background Technology

[0002] In the field of SCR (Selective Catalytic Reduction) system fault diagnosis, accurately acquiring acoustic signals during system operation is crucial for timely fault detection and diagnosis. Traditional sound collection methods often have many limitations and cannot meet the precise requirements for SCR system fault diagnosis.

[0003] On the one hand, existing sound collection devices are not flexible or stable enough in terms of installation and fixation. For example, some devices are difficult to adapt to jet valve end tubes of different sizes, the installation process is complicated and prone to loosening, which not only affects the stability of sound collection but may also lead to inaccurate acoustic signals. On the other hand, the installation and maintenance of directional microphone arrays—a key component of sound collection—are not convenient enough. When a directional microphone array or its mounting base is damaged, it is difficult to replace it quickly and easily; often, the entire device needs to be replaced, increasing maintenance costs and time.

[0004] Furthermore, during sound collection, vibrations transmitted through the tube can interfere with acoustic signals, affecting the accuracy of fault diagnosis. Currently, some sound collectors lack effective vibration damping measures, failing to effectively reduce vibrations transmitted through the tube, thus lowering the quality of sound collection. Summary of the Invention

[0005] The purpose of this invention is to provide a sound collector and diagnostic method for SCR system fault diagnosis, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a sound collector for SCR system fault diagnosis, comprising multiple directional microphone arrays, which are distributed in a circular shape on the outer ring surface of an elastic hoop. The elastic hoop is fitted onto the tube body at the end of the injection valve. The directional microphone arrays are inserted into a mounting base, which is slidably connected to the outer ring surface of the elastic hoop. The surface of the mounting base has slots, and clamping blocks are inserted into the side walls of the slots. An insert plate is inserted into the inside of the slots, and the insert plate pushes the clamping blocks to clamp the directional microphone arrays inside the mounting base.

[0007] Preferably, the elastic hoop plate is an annular plate with a broken end. One end of the elastic hoop plate is provided with a dislocation groove 1 on the outer ring surface, and the other end of the elastic hoop plate is provided with a dislocation groove 2 on the inner ring surface. The dislocation groove 1 and the dislocation groove 2 are spliced in a dislocation manner. A plurality of equally spaced screw holes are provided on the surface of the dislocation groove 1. A hand-tightening screw is screwed on the other end of the elastic hoop plate. After the hand-tightening screw penetrates the other end of the elastic hoop plate, it is screwed into the screw hole.

[0008] Preferably, a rubber gasket is fixed on the inner ring surface of the elastic hoop plate, and the rubber gasket is clamped between the elastic hoop plate and the pipe body at the end of the injection valve.

[0009] Preferably, a plurality of reserved grooves are provided on the outer ring surface of the elastic hoop plate. The reserved grooves are in the shape of a "convex" groove. The width of the reserved groove is smaller than the width of the elastic hoop plate. The mounting seat is in the shape of a "convex" plate structure. The mounting seat is movably inserted into the reserved groove, and the width of the mounting seat is smaller than the width of the reserved groove. Through holes are provided on the surface of the reserved groove. A blocking strip is inserted into the through hole. One end of the blocking strip is fixed on the outer ring surface of the rubber gasket. The other end of the blocking strip is provided with an inclined surface, and the thickness of the blocking strip is greater than the depth of the through hole.

[0010] Preferably, a through hole is provided on one side wall of the reserved groove. A screw is inserted into the through hole. One end of the screw is fixed on the surface of the mounting seat. After the other end of the screw extends out of the through hole, it is screwed with a nut.

[0011] Preferably, there are two slots, and the two slots are symmetrically distributed about the notch of the mounting seat. A jack is provided on one side wall of the slot. A notch is provided on the inner wall of the mounting seat. The height of the notch is greater than the height of the jack. An elastic rubber band is fixed between the top surface and the bottom surface of the notch. One end of the clamping block penetrates the jack and is fixed on the surface of the elastic rubber band. The other end of the clamping block is provided with an inclined surface at the top. After the insertion plate is pushed down, it squeezes the clamping block along the inclined surface. The clamping block squeezes the elastic rubber band to deform, and the clamping block tightly clamps the elastic rubber band on one side of the directional sound pickup microphone array.

[0012] Preferably, clamping grooves are formed on both sides of the insertion plate. Rubber clamping strips are installed at the corresponding positions of the slots and the clamping grooves. The rubber clamping strips can be clamped in the clamping grooves; Traction plates are fixed at both ends of the top surface of the two insertion plates. The two ends of the traction plate are respectively fixed on the top surfaces of the two groups of insertion plates, and an arc-shaped pull ring is integrally formed in the middle of the traction plate.

[0013] An SCR system fault diagnosis method includes the following steps:

[0014] Acoustic signal acquisition: Using a directional sound pickup microphone array to collect acoustic signals in real time during the SCR urea injection process;

[0015] Signal preprocessing: The acquired acoustic signal undergoes filtering, normalization, and noise suppression preprocessing to obtain the preprocessed acoustic signal. The preprocessed acoustic signal is then further processed to obtain the corresponding spectrogram and Mel-frequency cepstral coefficient time sequence.

[0016] Fault classification and alarm: A dual-branch deep learning architecture is used for fault classification. One branch processes the spectrogram through a convolutional neural network, and the other branch analyzes the time sequence of the Mel frequency cepstral coefficients through a long short-term memory network. Finally, the two types of features are fused to output the fault classification result.

[0017] Preferably, the noise suppression preprocessing specifically includes: using a blind source separation algorithm to separate the acoustic signal of the target sound source, i.e., the sound of the SCR urea injection valve, from the acoustic signal after filtering preprocessing and normalization preprocessing, while suppressing background noise; subsequently, applying frequency band focusing technology to enhance the acoustic signal of the target sound source frequency band to obtain the acoustic signal.

[0018] Preferably, the dual-branch deep learning architecture in the fault classification and alarm steps is specifically implemented as follows:

[0019] The dual-branch deep learning architecture in the fault classification and alarm process is specifically implemented as follows:

[0020] Convolutional Neural Network Branch: The spectrogram is taken as input, and the spatial hierarchical features in the spectrogram are automatically learned through the convolutional layer. The pooling layer reduces the feature dimension to obtain the first feature.

[0021] Long Short-Term Memory Network Branch: Taking the Mel frequency cepstral coefficient time series as input, the second feature is obtained by utilizing the memory function of the long short-term memory network;

[0022] Feature fusion and classification decision: The first feature extracted by the convolutional neural network branch and the second feature extracted by the long short-term memory network branch are fused to form a comprehensive feature vector through weighted averaging or concatenation. The comprehensive feature vector is input into the classification layer to output the final fault classification result, including normal state, blockage fault and leakage fault. A fault probability threshold is set. When the probability of any fault type in the classification result exceeds the threshold, the on-board OBD system alarm is immediately triggered and the fault type is clearly indicated.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The present invention proposes a sound collector and diagnostic method for SCR system fault diagnosis. It employs an elastic clamp plate fitted onto the pipe body at the end of the injection valve. The elastic clamp plate is an annular plate with a broken end, featuring a first misalignment groove at one end and a second misalignment groove at the other. A closed connection is achieved through misaligned splicing and the engagement of a hand-tightened screw with a threaded hole. This design allows the elastic clamp plate to adapt to pipe bodies of different sizes, simplifying and facilitating installation. Furthermore, the rubber gasket clamping between the elastic clamp plate and the pipe body prevents the elastic clamp plate from loosening and effectively reduces vibrations transmitted through the pipe body, thus improving the stability and accuracy of sound collection.

[0025] The mounting base, equipped with a directional microphone array, is slidably connected to a pre-drilled groove on the outer ring of the elastic clamp. The mounting base is positioned and secured by a stop bar and a screw and nut. During installation, the mounting base presses against the stop bar along its inclined surface, causing the stop bar to retract into the through hole. After the mounting base passes the stop bar, the stop bar is springy back and popped out by a rubber gasket, blocking it on one side. Simultaneously, the screw passes through the through hole and is tightened with a nut, further enhancing the connection between the mounting base and the elastic clamp. This installation method is simple to operate, allows for quick installation of the mounting base, and improves work efficiency.

[0026] A slot is created on the surface of the mounting base, with a clamping block inserted into the side wall of the slot and an insert plate inserted inside. The insert plate pushes the clamping block to hold the directional microphone array. When it is necessary to replace the directional microphone array or the mounting base individually, simply pull the insert plate out using the traction plate. The elastic rubber band will rebound, causing the clamping block to release its grip on the directional microphone array, allowing the microphone array to be removed. When installing a new directional microphone array, insert the insert plate back in and push it down to allow the clamping block to hold the array in place. Simultaneously, rubber clips insert into the slots to prevent the insert plate from shifting. This design facilitates the replacement of a single component when the directional microphone array or mounting base is damaged, reducing maintenance costs and time.

[0027] The rubber gaskets not only act as shock absorbers between the elastic clamp and the tube body, but also work in conjunction with the baffles. The directional microphone array provides elastic traction to the baffles, further enhancing the stability of the device. Simultaneously, pre-inserting the directional microphone array into the mounting base prevents damage to its bottom from impacts, protecting the acoustic signal collection components, improving the quality and reliability of sound collection, and facilitating more accurate fault diagnosis of the SCR system.

[0028] By using non-invasive acoustic feature analysis, abnormal conditions (such as blockage, leakage, pump failure, etc.) in the urea injection process of the SCR system can be detected in real time, thereby improving fault diagnosis efficiency and reducing maintenance costs. Attached Figure Description

[0029] Figure 1This is a schematic diagram of the structure of the present invention;

[0030] Figure 2 for Figure 1 Sectional view of the structure at point AA;

[0031] Figure 3 for Figure 2 Enlarged schematic diagram of the structure at point C;

[0032] Figure 4 for Figure 3 Enlarged schematic diagram of the structure at point D;

[0033] Figure 5 for Figure 1 Structural cross-section view at point BB;

[0034] Figure 6 This is a schematic diagram of the elastic hoop structure of the present invention;

[0035] Figure 7 This is a schematic diagram of the mounting base structure of the present invention;

[0036] Figure 8 This is a schematic diagram of the connection structure between the insert plate and the traction plate of the present invention.

[0037] In the diagram: 1. Elastic hoop plate, 101. Misalignment groove 1, 1011. Screw hole 1011. 102. Misalignment groove 2. 1021. Rubber gasket 103. 104. Reserved groove 104. 1041. 1042. 1043. 1043. Mounting base 2. 2. Screw 201. 202. 203. 2031. 204. 205. 2051. 2051. 3. 3. 3. 4. Insert plate 4. 401. 5. Clamping block 5. 6. Traction plate 6. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the present invention clear and complete, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some, not all, embodiments of the present invention, and are merely illustrative of the embodiments of the present invention. They are not intended to limit 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.

[0039] Example 1, please refer to Figures 1 to 8, the present invention provides a technical solution: a sound collector for SCR system fault diagnosis, which includes a plurality of directional sound pickup microphone arrays 3. The plurality of directional sound pickup microphone arrays 3 are circularly distributed on the outer ring surface of the elastic hoop plate 1. The elastic hoop plate 1 is sleeved and installed on the pipe body at the end of the injection valve. The elastic hoop plate 1 is an annular plate with an open end. One end of the elastic hoop plate 1 is provided with a misaligned groove one 101 on the outer ring surface, and the other end of the elastic hoop plate 1 is provided with a misaligned groove two 102 on the inner ring surface. The misaligned groove one 101 and the misaligned groove two 102 are misaligned and spliced. A plurality of equally spaced screw holes 1011 are provided on the surface of the misaligned groove one 101. A hand-tightening screw 1021 is screwed to the other end of the elastic hoop plate 1. After the hand-tightening screw 1021 penetrates through the other end of the elastic hoop plate 1, it is screwed into the screw hole 1011; a rubber gasket 103 is fixed on the inner ring surface of the elastic hoop plate 1, and the rubber gasket 103 is clamped between the elastic hoop plate 1 and the pipe body at the end of the injection valve.

[0040] When installing the elastic hoop plate 1, the elastic hoop plate 1 is掰开from both ends to generate elastic deformation, and the elastic hoop plate 1 is buckled on the pipe body from both ends of the elastic hoop plate 1. After releasing the elastic hoop plate 1, the elastic hoop plate 1 rebounds and clamps on the pipe body. At this time, the two ends of the elastic hoop plate 1 are misaligned and spliced through the misaligned groove one 101 and the misaligned groove two 102. By pushing the two ends of the elastic hoop plate 1, the hand-tightening screw 1021 and the adjacent screw hole 1011 are made to correspond, and then the hand-tightening screw 1021 is screwed and inserted into the screw hole 1011 to complete the closed connection of the two ends of the elastic hoop plate 1. At this time, the rubber gasket 103 is tightly clamped between the elastic hoop plate 1 and the pipe body, preventing the elastic hoop plate 1 from loosening and reducing the vibration transmitted by the pipe body.

[0041] In order to install the mounting seat 2 equipped with the directional sound pickup microphone array 3 on the elastic hoop plate 1, it is proposed that:

[0042] The directional sound pickup microphone array 3 is inserted into the mounting seat 2. The mounting seat 2 is slidably connected to the outer ring surface of the elastic hoop plate 1. A plurality of reserved grooves 104 are provided on the outer ring surface of the elastic hoop plate 1. The reserved grooves 104 are "convex"-shaped grooves. The width of the reserved grooves 104 is smaller than the width of the elastic hoop plate 1. The mounting seat 2 is a "convex"-shaped plate structure. The mounting seat 2 is movably inserted into the reserved grooves 104, and the width of the mounting seat 2 is smaller than the width of the reserved grooves 104. Through holes 1042 are provided on the surface of the reserved grooves 104. A blocking strip 1043 is inserted into the interior of the through holes 1042. One end of the blocking strip 1043 is fixed on the outer ring surface of the rubber gasket 103. The other end of the blocking strip 1043 is provided with an inclined surface, and the thickness of the blocking strip 1043 is greater than the depth of the through holes 1042; a through hole 1041 is provided on one side wall of the reserved grooves 104. A screw 201 is inserted into the interior of the through hole 1041. One end of the screw 201 is fixed on the surface of the mounting seat 2. After the other end of the screw 201 extends out of the through hole 1041, it is screwed with a nut 202. It should be noted that the Chinese word "掰开" in the original text seems to be an incorrect or incomplete expression. I translated it as "掰开" according to the literal meaning, but it may need to be adjusted according to the actual situation to make the translation more accurate and fluent.

[0043] Beforehand, insert the directional microphone array 3 into the mounting base 2 to prevent damage to the bottom of the directional microphone array 3. Push the mounting base 2 into the reserved slot 104 from one side. During this process, the mounting base 2 presses against the retaining strip 1043 along the inclined surface. The retaining strip 1043 compresses the rubber pad 103, causing it to deform and retract into the through hole 1042. After the mounting base 2 passes the retaining strip 1043, the retaining strip 1043 is rebounded and ejected by the rubber pad 103. The part of 043 that pops out is blocked on one side of the mounting base 2. At this time, the mounting base 2 is clamped between the stop bar 1043 and the reserved slot 104. The directional microphone array 3 not only reduces the vibration transmitted by the tube body, but also realizes the elastic traction of the stop bar 1043. After the mounting base 2 is limited by the stop bar 1043, the screw 201 passes through the through hole 1041. In order to further improve the connection between the mounting base 2 and the elastic hoop 1, the nut 202 is screwed to the end of the screw 201 and locked.

[0044] To allow the directional microphone array 3 to be removed from the mounting base 2, it is convenient to replace one of the structures if either the directional microphone array 3 or the mounting base 2 is damaged.

[0045] The surface of the mounting base 2 has a slot 203. A clamping block 5 is inserted into the side wall of the slot 203, and an insert plate 4 is inserted into the inside of the slot 203. The insert plate 4 pushes the clamping block 5 to clamp the directional microphone array 3 inside the mounting base 2. There are two slots 203, which are symmetrically distributed about the slot opening of the mounting base 2. An insertion hole 204 is opened on one side wall of the slot 203. A notch 205 is opened on the inner wall of the mounting base 2. The height of the notch 205 is greater than the height of the insertion hole 204. An elastic rubber band 2051 is fixed between the top and bottom surfaces of the notch 205. One end of the clamping block 5 passes through the insertion hole 204 and is fixed to the surface of the elastic rubber band 2051. The other end of 5 has a sloping surface at the top. After the insert plate 4 is pushed down, it pushes the clamping block 5 along the sloping surface. The clamping block 5 squeezes the elastic rubber band 2051 to deform, and the clamping block 5 tightly clamps the elastic rubber band 2051 to one side of the directional microphone array 3. The two sides of the insert plate 4 have slots 401. The slot 203 and the slot 401 are equipped with rubber strips 2031 at the corresponding positions. After the insert plate 4 is inserted into the slot 203, the rubber strips 2031 are inserted into the slot 401. The top surfaces of the two insert plates 4 are fixed with traction plates 6 at both ends. The two ends of the traction plates 6 are fixed to the top surfaces of the two sets of insert plates 4 respectively, and the middle part of the traction plates 6 is integrally formed with an arc-shaped pull ring.

[0046] The specific operation when the directional microphone array 3 needs to be replaced separately is as follows: hook two fingers on the pull rings in the middle of the two traction plates 6 respectively, pull up the traction plates 6 to drive the insert plate 4 out of the slot 203. At this time, the elastic rubber band 2051 rebounds and pushes the clamping block 5 to move into the slot 203. Remove the clamping block 5 from the directional microphone array 3 and pull the directional microphone array 3 out of the mounting base 2. After inserting the new directional microphone array 3 into the mounting base 2, insert the insert plate 4 back into the slot 203. During the process of pushing down the insert plate 4, the insert plate 4 pushes the clamping block 5 along the inclined surface. The clamping block 5 retracts into the insertion hole 204. After the clamping block 5 squeezes the elastic rubber band 2051 and deforms, it clamps one side of the directional microphone array 3 to prevent the directional microphone array 3 from falling off the mounting base 2. The rubber clip 2031 is inserted into the slot 401 to prevent the insert plate 4 from shaking in the slot 203.

[0047] Instructions for using a sound collector for SCR system fault diagnosis:

[0048] 1. Installation of the elastic clamp plate: Pry open the elastic clamp plate 1 from both ends to induce elastic deformation. Secure the pried-open elastic clamp plate 1 onto the pipe body at the end of the injection valve. Release the elastic clamp plate 1; it will spring back and clamp onto the pipe body. At this point, the two ends of the elastic clamp plate 1 are misaligned and spliced ​​through misalignment groove 101 and misalignment groove 102. Push the two ends of the elastic clamp plate 1 until the hand-tightening screw 1021 aligns with the adjacent screw hole 1011. Then, tighten the hand-tightening screw 1021 into the screw hole 1011 to complete the closed connection of the two ends of the elastic clamp plate 1. At this point, the rubber gasket 103 is tightly clamped between the elastic clamp plate 1 and the pipe body, preventing the elastic clamp plate 1 from loosening and reducing vibration transmitted through the pipe body.

[0049] II. Assembly and Installation of Mounting Base and Directional Microphone Array: Insert the directional microphone array 3 into the mounting base 2 beforehand to prevent damage to the bottom of the directional microphone array 3. Push the mounting base 2, with the directional microphone array 3 installed, into the pre-drilled slot 104 from one side. During this process, the mounting base 2 presses against the retaining strip 1043 along its inclined surface. The retaining strip 1043 deforms the rubber pad 103, and the retaining strip 1043 retracts into the through hole 1042. After the mounting base 2 passes the retaining strip 1043, the retaining strip 1043 is rebounded and supported by the rubber pad 103, popping out. The popped-out portion of the retaining strip 1043 blocks one side of the mounting base 2. At this point, the mounting base 2 is clamped between the retaining strip 1043 and the pre-drilled slot 104. After the mounting base 2 is limited by the stop bar 1043, the screw 201 passes through the through hole 1041, and the nut 202 is screwed onto the end of the screw 201 to lock it, further improving the connection between the mounting base 2 and the elastic hoop 1.

[0050] III. Fixing the directional microphone array on the mounting base: The surface of the mounting base 2 has a slot 203, and a clamping block 5 is inserted into the side wall of the slot 203. An insert plate 4 is inserted into the inside of the slot 203. There are two slots 203, symmetrically distributed about the opening of the mounting base 2. One side wall of the slot 203 has an insertion hole 204. The inner wall of the mounting base 2 has a notch 205, the height of which is greater than the height of the insertion hole 204. An elastic rubber band 2051 is fixed between the top and bottom surfaces of the notch 205. One end of the clamping block 5 passes through the insertion hole 204 and is fixed to the surface of the elastic rubber band 2051. The other end of the clamping block 5 has a bevel at the top. The insert plate 4 is pushed down into the slot 203. The insert plate 4 pushes the clamping block 5 along the inclined surface. The clamping block 5 compresses the elastic rubber band 2051 and deforms it. The clamping block 5 tightly clamps the elastic rubber band 2051 to one side of the directional microphone array 3, thus fixing the directional microphone array 3 on the mounting base 2. At the same time, slots 401 are formed on both sides of the insert plate 4. Rubber clips 2031 are installed on the inner wall of the slot 203 at positions corresponding to the slots 401. The rubber clips 2031 can be engaged in the slots 401. After the insert plate 4 is inserted into the slot 203, the rubber clips 2031 are engaged in the slots 401, preventing the insert plate 4 from bouncing in the slot 203.

[0051] IV. Replacement of the Directional Microphone Array: When it is necessary to replace the directional microphone array 3 separately, hook two fingers onto the pull rings in the middle of the two traction plates 6, and pull up the traction plates 6 to pull the insert plate 4 out of the slot 203. At this time, the elastic rubber band 2051 rebounds and pushes the clamping block 5 into the slot 203, releasing the clamping block 5 from the directional microphone array 3. Remove the directional microphone array 3 from the mounting base 2. After inserting the new directional microphone array 3 into the mounting base 2, insert the insert plate 4 back into the slot 203. During the process of pushing down the insert plate 4, the insert plate 4 pushes the clamping block 5 along the inclined surface. The clamping block 5 retracts into the insertion hole 204, and the clamping block 5 squeezes the elastic rubber band 2051 and deforms to clamp one side of the directional microphone array 3, preventing the directional microphone array 3 from falling off the mounting base 2. The rubber clip 2031 is inserted into the slot 401, completing the replacement and fixation of the directional microphone array 3.

[0052] Example 2, based on Example 1, proposes a fault diagnosis method for SCR systems, including hardware acquisition devices, signal processing algorithms and deep learning models, which, combined with dynamic workflow and verification data, form a complete technical closed loop.

[0053] A method for diagnosing faults in an SCR system includes the following steps:

[0054] (1) Acoustic signal acquisition:

[0055] The directional microphone array 3 acquires acoustic signals; the acoustic signals are then transmitted in real time to the vehicle ECU or edge computing device via a high-precision data acquisition card (sampling rate ≥ 44.1 kHz);

[0056] (2) Signal preprocessing: The acoustic signal is preprocessed by bandpass filtering (1-10 kHz) and dynamic normalization. Then, the blind source separation algorithm is used to separate the acoustic signal of the target sound source, namely the action sound of the SCR urea injection valve, from the preprocessed acoustic signal, while suppressing background noise. Subsequently, the frequency band focusing technology is applied to enhance the acoustic signal of the target sound source frequency band to obtain the preprocessed acoustic signal, ensuring that the quality of the preprocessed acoustic signal meets the requirements of subsequent analysis, and obtaining the spectrogram and Mel frequency cepstral coefficient time sequence corresponding to the preprocessed acoustic signal.

[0057] In this embodiment, in the prior art, the blind source separation algorithm is an unsupervised learning algorithm. The blind source separation (BSS) algorithm separates the independent source signals in the preprocessed acoustic signal (mixed signal) without prior knowledge. The independent source signal is the acoustic signal of the target sound source (usually in the 2–10 kHz range). By determining the acoustic signal of the target sound source, the noise suppression effect can be achieved.

[0058] In this embodiment, the frequency band focusing technology specifically includes: bandpass filtering or frequency band weighting, narrowband bandpass filter, weighted frequency band amplification or spectral threshold enhancement.

[0059] (3) One branch of the pre-trained dual-branch deep learning architecture processes the spectrogram through a convolutional neural network (CNN), receives the spectrogram as input, automatically learns the spatial hierarchical features in the spectrogram through the convolutional layer, and reduces the feature dimension through the pooling layer to obtain the first feature.

[0060] (4) The other branch of the pre-trained dual-branch deep learning architecture analyzes the time sequence of Mel frequency cepstral coefficients through a long short-term memory network (LSTM) to obtain the second feature;

[0061] In this embodiment, steps (3) and (4) are performed simultaneously.

[0062] (5) The first feature and the second feature are processed into a comprehensive feature vector by weighted averaging or splicing; the comprehensive feature vector is input into the classification layer of the pre-trained dual-branch deep learning architecture, and the final fault classification result is output, including normal state, blockage fault and leakage fault; a fault probability threshold is set, and when the probability of any fault type in the classification result exceeds the threshold, the vehicle OBD system alarm is immediately triggered and the fault type is clearly indicated.

[0063] In this embodiment, the spectrogram size is preferably 128×128 pixels.

[0064] In this embodiment, the dimension and sequence length of the feature vector of the Mel frequency cepstral coefficient time series are: 13 dimensions × 100 time steps, where the 13 dimensions specifically represent: 13-dimensional Mel frequency cepstral coefficients = energy + 12 coefficients that describe the shape of the spectral envelope by order (these 12 coefficients come from the discrete cosine transform of the energy of the Mel filter bank, which is a "compressed representation" and corresponds to the shape components of the spectral envelope at different orders).

[0065] In the dynamic workflow, the system continuously acquires acoustic signals in 2-second analysis windows, sequentially completing filtering, feature extraction, and model inference. If the fault probability exceeds 90%, an OBD alarm is triggered and the fault type is located, with a diagnostic delay of less than 200 milliseconds. It also supports online learning and operating condition adaptation, dynamically optimizing feature thresholds based on engine speed and urea injection volume, and achieving iterative model updates through cloud collaboration.

[0066] Technical verification shows that in laboratory bench tests, the system achieved a 98.5% detection rate for blockages, leaks, and pump failures, with a false alarm rate of less than 2%. Real-vehicle road tests successfully alerted multiple early-stage faults, significantly outperforming traditional threshold alarm methods. Furthermore, the system possesses multi-modal data fusion capabilities, which can combine pressure sensor data to improve diagnostic confidence and supports cross-vehicle vehicle migration applications, providing an efficient and low-cost solution for intelligent operation and maintenance of SCR systems.

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sound collector for diagnosing faults of an SCR system, comprising a plurality of directional sound collecting microphone arrays (3) which are circumferentially distributed on the outer surface of an elastic hoop plate (1) which is sleeved and mounted on the pipe body at the end of the injection valve, characterized in that: The directional microphone array (3) is inserted into the mounting seat (2), the mounting seat (2) is slidably and detachably connected to the outer ring surface of the elastic hoop plate (1), the surface of the mounting seat (2) is provided with a slot (203), the side wall of the slot (203) is provided with a clamping block (5), and the inside of the slot (203) is provided with an insertion plate (4), the insertion plate (4) pushes and extrudes the clamping block (5) to clamp the directional microphone array (3) in the mounting seat (2). The elastic hoop plate (1) is a ring plate with disconnected ends, a staggered slot one (101) is formed in the outer ring surface of one end of the elastic hoop plate (1), a staggered slot two (102) is formed in the inner ring surface of the other end of the elastic hoop plate (1), the staggered slot one (101) and the staggered slot two (102) are staggered and spliced, a plurality of equidistantly distributed screw holes (1011) are formed in the surface of the staggered slot one (101), a hand screw rod (1021) is screwed in the other end of the elastic hoop plate (1) and then screwed in the screw hole (1011); The inner ring surface of the elastic hoop plate (1) is fixed with a rubber gasket (103), and the rubber gasket (103) is clamped between the elastic hoop plate (1) and the pipe body at the end of the injection valve.

2. The sound collector for diagnosing a fault of an SCR system according to claim 1, characterized in that: The outer ring surface of the elastic hoop plate (1) is provided with a plurality of reserved slots (104), the reserved slots (104) are "convex" shaped slots, the width of the reserved slots (104) is smaller than the width of the elastic hoop plate (1), the mounting seat (2) is a "convex" shaped plate structure, the mounting seat (2) is movably inserted into the reserved slots (104), and the width of the mounting seat (2) is smaller than the width of the reserved slots (104), a through hole (1042) is formed in the surface of the reserved slots (104), a blocking strip (1043) is inserted into the through hole (1042), one end of the blocking strip (1043) is fixed to the outer ring surface of the rubber gasket (103), the other end of the blocking strip (1043) is provided with an inclined surface, and the thickness of the blocking strip (1043) is greater than the depth of the through hole (1042).

3. The sound collector for diagnosing a fault of an SCR system according to claim 2, characterized in that: A through hole (1041) is formed in one side wall of the reserved slot (104), a screw rod (201) is inserted into the through hole (1041), one end of the screw rod (201) is fixed to the surface of the mounting seat (2), and the other end of the screw rod (201) is screwed with a nut (202) after penetrating the through hole (1041).

4. The sound collector for diagnosing a fault of an SCR system according to claim 1, characterized in that: The two insertion slots (203) are symmetrically arranged on the two sides of the slot of the mounting seat (2), one side wall of the insertion slot (203) is provided with a insertion hole (204), the inner wall of the mounting seat (2) is provided with a notch (205), the height of the notch (205) is greater than the height of the insertion hole (204), the top surface and the bottom surface of the notch (205) are fixedly connected with an elastic rubber belt (2051), one end of the clamping block (5) penetrates through the insertion hole (204) and is fixed on the surface of the elastic rubber belt (2051), the other end of the clamping block (5) is provided with an inclined surface at the top, the plug-in plate (4) is pushed downward and pushes the clamping block (5) along the inclined surface, the clamping block (5) extrudes the elastic rubber belt (2051) to deform, and the clamping block (5) tightly clamps the elastic rubber belt (2051) on one side of the directional microphone array (3).

5. The sound collector for diagnosing a fault of an SCR system according to claim 4, characterized in that: The two sides of the plug-in plate (4) are provided with clamping grooves (401), the inner wall of the insertion slot (203) is provided with rubber clamping strips (2031) at positions corresponding to the clamping grooves (401), and the rubber clamping strips (2031) can be clamped in the clamping grooves (401); the top surfaces of the two plug-in plates (4) are fixedly connected with traction plates (6) at two ends, the two ends of the traction plate (6) are fixedly connected with the top surfaces of the two groups of plug-in plates (4), and the middle part of the traction plate (6) is integrally formed with a circular-arc-shaped pull ring.

6. A method for diagnosing a fault of an SCR system, wherein the acoustic signal is collected by the sound collector for diagnosing a fault of an SCR system according to any one of claims 1-5, characterized in that: The method comprises the following steps: Acoustic signal acquisition: a directional microphone array (3) is used to collect acoustic signals in real time during the SCR urea injection process; Signal preprocessing: the collected acoustic signals are subjected to filtering preprocessing, normalization preprocessing and noise suppression preprocessing to obtain preprocessed acoustic signals, and the preprocessed acoustic signals are processed to obtain corresponding spectrograms and mel-frequency cepstral coefficient time series: Fault classification and alarm: a pre-trained double-branch deep learning architecture is used for fault classification, one branch processes the spectrograms through a convolutional neural network, and the other branch analyzes the mel-frequency cepstral coefficient time series through a long short-term memory network, and finally the two types of features are fused to output fault classification results.

7. The method of claim 6, wherein the step of determining the fault of the SCR system comprises the steps of: determining whether the SCR system is in a fault state; and determining whether the fault is a fault of the SCR system. The noise suppression preprocessing specifically comprises: using a blind source separation algorithm to separate the acoustic signals of the target sound source, i.e. the action sound of the SCR urea injection valve, from the acoustic signals after filtering preprocessing and normalization preprocessing, while suppressing background noise; subsequently, a frequency band focusing technology is applied to strengthen the acoustic signals of the target sound source frequency band to obtain the preprocessed acoustic signals.

8. The method of claim 6, wherein: The double-branch deep learning architecture in the fault classification and alarm step is specifically implemented as: Convolutional neural network branch: the spectrograms are taken as input, spatial hierarchical features in the spectrograms are automatically learned through a convolutional layer, and a pooling layer is used to reduce the feature dimension to obtain first features; Long short-term memory network branch: the mel-frequency cepstral coefficient time series are taken as input, and the memory function of the long short-term memory network is used to obtain second features; Feature fusion and classification decision: the first feature extracted by the convolutional neural network branch and the second feature extracted by the long short-term memory network branch are combined into a comprehensive feature vector by weighted average or splicing; the comprehensive feature vector is input into a classification layer, and the final fault classification result is output, including normal state, blockage fault and leakage fault; a fault probability threshold is set, and when the probability of any fault type in the classification result exceeds the threshold, the vehicle OBD system alarm is triggered immediately, and the fault type is indicated.

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