A fault diagnosis method for a hydrogen energy heat engine injection system of a vehicle

Abstract

The application discloses a kind of vehicle hydrogen energy heat engine injection system fault diagnosis method, including each setting acoustic sensor acquisition preset direction acoustic signal, and the acoustic signal of acquisition is amplified;The amplified acoustic signal is input to MCU and is operated, obtains multiple corresponding sound pressure level-frequency curves;Obtain the sound pressure level-frequency curve of each group respectively corresponding sound pressure level continuous variation frequency band and corresponding sound pressure level variation range;The sound pressure level-frequency curve of each group sound pressure level continuous variation frequency band and corresponding sound pressure level variation range under the condition of analog explosion criticality is respectively compared with reference, whether the injection system appears fault is judged, on the one hand, acoustic detection can better guarantee the safety in the process of air inlet injection, on the other hand, the sensitivity of acoustic sensor is high, the application creates the detection air inlet flow acoustic signal frequency band, detection result is more fine, can be more accurate to grasp to abnormal situation.

Description

Technical Field

[0001] This invention relates to the field of automotive engine technology, and in particular to a fault diagnosis method for automotive hydrogen fuel cell injection systems. Background Technology

[0002] Hydrogen, as a carbon-free clean energy source, produces only water when burned, achieving near-zero emissions of carbon and pollutants. Using hydrogen fuel cell engines can advance the carbon neutrality process. Currently, hydrogen fuel cell engines, both domestically and internationally, are in the research stage, mostly employing port injection hydrogen supply systems. These systems are characterized by low hydrogen supply pressure, typically 5 bar, resulting in high hydrogen tank utilization and long driving range. However, they suffer from low power density, low thermal efficiency, and a high risk of backfire. This is primarily due to the low density of hydrogen; port injection occupies a large portion of the intake volume, reducing charging efficiency and leading to low power density and efficiency. Furthermore, the high hydrogen density within the intake manifold means that if a hot spot occurs or gas flows back into the intake manifold during the intake phase, it can cause hydrogen combustion or backfire explosion, resulting in severe structural damage.

[0003] Currently, there are no good testing and diagnostic methods for hydrogen fuel cell injection systems in existing technologies. The conventional approach is to use periodic disassembly and replacement to ensure the stability of the injection system. On the one hand, this will waste engine structure and hydrogen resources. On the other hand, when the hydrogen pressure in the hydrogen tank is high, rash disassembly and replacement may pose an explosion risk. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the problems existing in the above-mentioned hydrogen-powered heat engine injection systems, the present invention is proposed.

[0006] Therefore, the technical problem solved by this invention is to address the issue that existing detection and diagnosis methods for hydrogen fuel cell injection systems result in both a waste of engine structure and hydrogen resources, and the risk of explosion when disassembling and reassembling the system hastily when the hydrogen pressure in the hydrogen tank is high.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a fault diagnosis method for a vehicle hydrogen fuel cell injection system, comprising a set of acoustic sensors disposed on the inner wall of the injection system intake duct, wherein the set of acoustic sensors is used to diagnose faults in the injection system, and the diagnosis method includes: S1: each of the acoustic sensors acquires an acoustic signal in a preset direction and amplifies the acquired acoustic signal; S2: the amplified acoustic signal is input to an MCU for calculation to obtain multiple sets of corresponding sound pressure level-frequency curves; S3: each... S4: Obtain the sound pressure level at each frequency point on the group sound pressure level-frequency curve, and obtain the corresponding continuous frequency band and range of sound pressure level variation on each group sound pressure level-frequency curve; S5: Compare the continuous frequency band and range of sound pressure level variation of each group with the sound pressure level-frequency curve under the simulated explosion critical condition. When the difference between the range of sound pressure level variation of each group under the continuous frequency band and the sound pressure level of that frequency band on the sound pressure level-frequency curve under the simulated explosion critical condition exceeds the threshold, the injection system is defined as having a fault.

[0008] In a preferred embodiment of the fault diagnosis method for the automotive hydrogen fuel cell injection system described in this invention, a set of acoustic sensors is arranged around the inner wall of the injection system intake duct.

[0009] As a preferred embodiment of the fault diagnosis method for the automotive hydrogen fuel cell injection system described in this invention, three acoustic sensors are arranged in a triangular configuration around the inner wall of the injection system's air intake duct.

[0010] As a preferred embodiment of the fault diagnosis method for the automotive hydrogen fuel cell injection system described in this invention, the preset direction is the current 90° direction of the sound sensor, and the directional acquisition direction is towards the center of the injection system's air intake.

[0011] As a preferred embodiment of the fault diagnosis method for the automotive hydrogen fuel cell injection system described in this invention, the acoustic signal is amplified to 1.5 to 1.8 times the original sound pressure level.

[0012] As a preferred embodiment of the fault diagnosis method for the automotive hydrogen fuel cell injection system described in this invention, the acquired acoustic signal is amplified to 1.5 times, 1.6 times, or 1.8 times the original sound pressure level.

[0013] As a preferred embodiment of the fault diagnosis method for the automotive hydrogen fuel cell injection system described in this invention, the method for obtaining the continuous sound pressure level variation frequency bands and corresponding sound pressure level variation ranges on each set of sound pressure level-frequency curves specifically includes: detecting continuously decreasing or increasing frequency bands with two mid-frequency points in the sound pressure level-frequency curve; calculating the sound pressure level variation range in each continuously decreasing or increasing frequency band; comparing and determining the continuously decreasing or increasing frequency band with the largest sound pressure level variation range, defining this frequency band as the continuously decreasing sound pressure level variation frequency band, and obtaining its corresponding sound pressure level variation range.

[0014] In a preferred embodiment of the fault diagnosis method for a vehicle hydrogen fuel cell injection system according to the present invention, the sound pressure level difference value is obtained by the following formula.

[0015]

[0016] Where, α 大 To simulate the maximum sound pressure level in this frequency band on the sound pressure level-frequency curve under critical explosion conditions, α 小 To simulate the minimum sound pressure level in this frequency band on the sound pressure level-frequency curve under critical explosion conditions, β 大 β represents the maximum sound pressure level within each group's sound pressure level variation range. 小 This represents the minimum sound pressure level within each group's sound pressure level variation range.

[0017] In a preferred embodiment of the fault diagnosis method for the automotive hydrogen fuel cell injection system described in this invention, the threshold value is 1.0 dB.

[0018] The beneficial effects of this invention are as follows: This invention provides a fault diagnosis method for a vehicle hydrogen fuel cell injection system. A set of detection sensors is installed on the inner wall of the injection system's intake manifold. By detecting the frequency band and sound pressure level of acoustic signals, the method is used to diagnose abnormalities in the injection system. On the one hand, acoustic detection can better ensure the safety of the intake manifold injection process. On the other hand, the acoustic sensors have high sensitivity. This invention innovatively detects the frequency band of the acoustic signals flowing in the intake manifold, resulting in more refined detection results and a more accurate grasp of abnormal situations. This solves the problems of existing detection and diagnosis methods for hydrogen fuel cell injection systems, which on the one hand waste engine structure and hydrogen resources, and on the other hand, pose an explosion risk when the hydrogen pressure in the hydrogen tank is high, due to rash disassembly and reassembly. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0020] Figure 1 The overall flowchart of the fault diagnosis method for automotive hydrogen fuel cell injection system provided by the present invention.

[0021] Figure 2 This invention relates to a flowchart of a method for obtaining the corresponding continuous frequency bands of sound pressure level variation and the corresponding range of sound pressure level variation on each set of sound pressure level-frequency curves.

[0022] Figure 3 A set of sound pressure level-frequency curve illustrations provided for this invention. Detailed Implementation

[0023] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0024] Currently, there are no good testing and diagnostic methods for hydrogen fuel cell injection systems in existing technologies. The conventional approach is to use periodic disassembly and replacement to ensure the stability of the injection system. On the one hand, this will waste engine structure and hydrogen resources. On the other hand, when the hydrogen pressure in the hydrogen tank is high, rash disassembly and replacement may pose an explosion risk.

[0025] Therefore, please refer to Figure 1 This invention provides a fault diagnosis method for a vehicle hydrogen fuel cell injection system, including a set of acoustic sensors installed on the inner wall of the injection system's air intake duct. The acoustic sensors are used to diagnose faults in the injection system. The diagnosis method includes:

[0026] S1: Each acoustic sensor collects acoustic signals in a preset direction and amplifies the collected acoustic signals;

[0027] Furthermore, the collected acoustic signals are amplified to 1.5 to 1.8 times the original sound pressure level.

[0028] Amplifying the acquired acoustic signal refers to amplifying the acoustic signal acquired through the sound input device to prevent signal distortion.

[0029] Preferably, the acquired acoustic signal is amplified to 1.5, 1.6, or 1.8 times the original sound pressure level.

[0030] Additionally, the specific settings for the acoustic sensor's acoustic signal acquisition program are as follows:

[0031] import pyaudio

[0032] import numpy as np

[0033] import matplotlib.pyplot as plt

[0034] p = pyaudio.PyAudio()

[0035] RATE = 44100

[0036] CHANNELS = 1

[0037] FORMAT = pyaudio.paInt16

[0038] DEVICE_INDEX = 0

[0039] CHUNK = 1024

[0040] RECORD_SECONDS = 3

[0041] stream=p.open(rate=RATE,

[0042] channels=CHANNELS,

[0043] format=FORMAT,

[0044] input_device_index=DEVICE_INDEX,

[0045] frames_per_buffer=CHUNK,

[0046] input=True)

[0047] data = stream.read(CHUNK,exception_on_overflow=False)

[0048] data_16 = np.frombuffer(data,dtype=np.int16) .

[0049] S2: Input the amplified acoustic signal to the MCU for processing, and obtain multiple sets of corresponding sound pressure level-frequency curves. (See reference...) Figure 3 ;

[0050] Specifically, MCU refers to Microcontroller Unit. Converting sound signals into sound pressure level-frequency curves using Microcontroller Units is an existing technology, which will not be elaborated on here.

[0051] Additionally, the specific settings for the calculation program in the MCU are as follows:

[0052] The program language is:

[0053] mic_sensitivity = -39 # Capacitive microphone sensitivity

[0054] reference_0dBFS = np.power(10,mic_sensitivity / 20)*(2**15-

[0055] 1) *np.power(10, -94 / 20)

[0056] f_vec = RATE*np.arange(CHUNK / 2) / CHUNK

[0057] f_vec = f_vec[1:]

[0058] fft_data = (np.abs(np.fft.fft(data_16))

[0059] [0:int(np.floor(CHUNK / 2))]) / CHUNK

[0060] fft_data[1:] = 2*fft_data[1:]

[0061] fft_data_dB = 20*np.log10(fft_data[1:] / reference_0dBFS).

[0062] S3: Compare the sound pressure level at each frequency point on the sound pressure level-frequency curve of each group, and obtain the continuous frequency band of sound pressure level variation and the corresponding range of sound pressure level variation on the sound pressure level-frequency curve of each group.

[0063] For further details, please refer to Figure 2 Obtaining the continuous frequency bands of sound pressure level variation and the corresponding range of sound pressure level variation on each group of sound pressure level-frequency curves specifically includes:

[0064] The sound pressure level-frequency curve is tested for a frequency band where the number of mid-frequency points is a continuous decrease or increase of two items;

[0065] Calculate the range of sound pressure level variation in each consecutive decreasing or increasing frequency band;

[0066] By comparing the frequency bands with the largest continuous decrease or increase in sound pressure level, this frequency band is defined as the continuous sound pressure level variation band, and its corresponding sound pressure level variation range is obtained.

[0067] S4: Compare the continuous frequency bands of sound pressure level variation and the corresponding range of sound pressure level variation on the sound pressure level-frequency curve under simulated explosion critical conditions. When the difference between the range of sound pressure level variation and the sound pressure level under the corresponding frequency band on the sound pressure level-frequency curve under simulated explosion critical conditions exceeds the threshold, the injection system is defined as malfunctioning.

[0068] Furthermore, the sound pressure level difference is obtained using the following formula:

[0069]

[0070] Where, α 大 To simulate the maximum sound pressure level in this frequency band on the sound pressure level-frequency curve under critical explosion conditions, α 小 To simulate the minimum sound pressure level in this frequency band on the sound pressure level-frequency curve under critical explosion conditions, β 大 β represents the maximum sound pressure level within each group's sound pressure level variation range. 小 This represents the minimum sound pressure level within each group's sound pressure level variation range.

[0071] The threshold is 1.0 dB.

[0072] It should be noted that the sound pressure level-frequency curve under the simulated explosion critical conditions is generated by the computer in advance simulating the critical conditions under the normal operation of the air intake. Multiple simulations are performed to determine the critical explosion conditions or conditions near the critical explosion conditions. Acoustic signal unfolding diagrams under the critical conditions are collected. The simulation process is directly generated by a conventional simulation platform in the laboratory, which will not be elaborated further here.

[0073] Furthermore, a set of acoustic sensors are arranged around the inner wall of the injection system's air intake.

[0074] Priority is given to the use of three acoustic sensors arranged in a triangular configuration around the inner wall of the injection system's air intake.

[0075] Preferred, the preset direction is 90° to the current sound sensor, and the directional acquisition direction is towards the center of the injection system's air intake.

[0076] It should be noted that the sound sensor is an existing high-sensitivity sensor, which is equipped with an MCU computing unit and a wireless transmission unit, and wirelessly connects to an external receiver to transmit the detection results.

[0077] Furthermore, directional acquisition of acoustic signals in the 90° direction allows for a better acoustic analysis and overview of the airflow in the intake duct.

[0078] This invention provides a fault diagnosis method for a vehicle hydrogen fuel cell injection system. A set of detection sensors is installed on the inner wall of the injection system's intake manifold. By detecting the frequency band and sound pressure level of acoustic signals, the method is used to diagnose abnormalities in the injection system. On the one hand, acoustic detection can better ensure the safety of the intake manifold injection process. On the other hand, the acoustic sensors have high sensitivity. This invention innovatively detects the frequency band of the acoustic signals flowing in the intake manifold, resulting in more refined detection results and a more accurate grasp of abnormal conditions. This solves the problems of existing detection and diagnosis methods for hydrogen fuel cell injection systems, which on the one hand waste engine structure and hydrogen resources, and on the other hand, pose an explosion risk when the hydrogen pressure in the hydrogen tank is high, due to rash disassembly and reassembly.

[0079] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A fault diagnosis method for a hydrogen energy heat engine injection system for vehicles, characterized by: The method comprises a set of acoustic sensors arranged on the inner wall of the air inlet of the injection system, the set of acoustic sensors is used for fault diagnosis of the injection system, and the diagnosis method comprises, S1: each acoustic sensor collects acoustic signals in a preset direction and amplifies the collected acoustic signals; S2: input the amplified acoustic signals into an MCU for operation to obtain a plurality of corresponding sound pressure level-frequency curves; S3: compare the sound pressure levels of each frequency point on each group of sound pressure level-frequency curves respectively to obtain the corresponding sound pressure level continuous variation frequency band and the corresponding sound pressure level variation range of each group of sound pressure level-frequency curves; S4: compare the sound pressure level continuous variation frequency band and the corresponding sound pressure level variation range of each group of sound pressure level-frequency curves on the sound pressure level-frequency curve under the critical condition of simulated explosion respectively, and when the difference between the corresponding sound pressure level variation range of each group of sound pressure level continuous variation frequency band and the sound pressure level of the frequency band on the sound pressure level-frequency curve under the critical condition of simulated explosion exceeds a threshold value, the injection system is defined as being faulty; Wherein, obtaining the corresponding sound pressure level continuous variation frequency band and the corresponding sound pressure level variation range of each group of sound pressure level-frequency curves comprises, detecting a continuous decreasing or increasing frequency band with two frequency points in the sound pressure level-frequency curve; calculating the sound pressure level variation range in each continuous decreasing or increasing frequency band; comparing to obtain the continuous decreasing or increasing frequency band with the largest sound pressure level variation range, and defining the frequency band as the sound pressure level continuous variation frequency band, and obtaining the sound pressure level variation range corresponding thereto; Wherein, the sound pressure level difference is obtained by the following formula, Sound pressure level difference = | (a 大 - b 大 ) | + | (a 小 - b 小 ) | Wherein, αmax is the maximum sound pressure value of the frequency band on the sound pressure level-frequency curve under the critical condition of simulated explosion, αmin is the minimum sound pressure value of the frequency band on the sound pressure level-frequency curve under the critical condition of simulated explosion, βmax is the maximum sound pressure level corresponding to each group of sound pressure level variation ranges, and βmin is the minimum sound pressure level corresponding to each group of sound pressure level variation ranges.

2. The method of claim 1, wherein: A set of acoustic sensors are arranged around the inner wall of the air inlet of the injection system.

3. The method of claim 2, wherein: The acoustic sensors are arranged in a triangular shape around the inner wall of the air inlet of the injection system.

4. The method of claim 3, wherein the method further comprises: The preset direction is a direction 90° to the current acoustic sensor, and the directional collection direction is positive to the center of the air inlet of the injection system.

5. The method of claim 4, wherein: The collected acoustic signals are amplified to 1.5-1.8 times of the original sound pressure level.

6. The method of claim 5, wherein: The collected acoustic signals are amplified to 1.5 times, 1.6 times or 1.8 times of the original sound pressure level.

7. The method of claim 6, wherein the method further comprises: determining whether the hydrogen energy engine is in a normal state or an abnormal state based on the comparison result. The threshold value is 1.0 db.

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