IV-type hydrogen cylinder stress monitoring system, signal processing method thereof and IV-type hydrogen cylinder

Abstract

The invention discloses an IV-type hydrogen cylinder stress monitoring system, a signal processing method thereof and an IV-type hydrogen cylinder, and relates to the technical field of manufacturing of high-pressure hydrogen storage equipment. The carbon fiber winding layer stress monitoring structure and the liner stress monitoring structure are respectively arranged in a strain generation area of a carbon fiber winding layer and a strain generation area of the outer surface of a plastic liner in the IV-type hydrogen cylinder, so that the surface stress of the liner of the gas cylinder and the stress between carbon fiber winding layers can be dynamically monitored in real time; therefore, the IV-type hydrogen cylinder has the function of dynamically monitoring the stress between the carbon fiber winding layers and the stress of the inner container in real time. According to the signal processing method of the IV-type hydrogen cylinder stress monitoring system, high-frequency noise signals can be effectively filtered, low and medium-frequency signals can be reserved, and the surface stress of a carbon fiber winding layer and a plastic inner container can be accurately measured. The IV-type hydrogen cylinder is provided with the IV-type hydrogen cylinder stress monitoring system and has the function of dynamically monitoring the stress between carbon fiber winding layers and the stress of an inner container in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of high-pressure hydrogen storage equipment manufacturing, and in particular to a type IV hydrogen cylinder stress monitoring system and a signal processing method thereof, and a type IV hydrogen cylinder. Background Art

[0002] Currently, Type IV hydrogen cylinders primarily utilize a plastic liner wrapped around a carbon fiber composite material, with a typical service life of 15 to 20 years. Compared to Type III hydrogen cylinders, Type IV cylinders maintain higher stability over long-term use, and under the same pressure conditions, they can undergo more hydrogen filling and discharging cycles than Type III cylinders.

[0003] Frequent and prolonged hydrogen charging and discharging can exacerbate wear on the interface between the plastic liner and the carbon fiber, as well as wear between the carbon fiber winding layers. This can easily lead to carbon fiber filament breakage and potentially rupture of the cylinder. Therefore, preventative monitoring of structural stress at the interface between the plastic liner and the carbon fiber is crucial for improving the service life and safety of Type IV hydrogen cylinders.

[0004] However, current stress monitoring solutions for Type IV hydrogen cylinders rely on destructive sampling or offline testing, making it impossible to monitor stress changes and structural damage in Type IV cylinders in real time. This results in a lack of dynamic data monitoring of stress concentration areas in the cylinders, and a lack of necessary experimental data support for structural optimization design. Furthermore, traditional curing processes are unable to simultaneously monitor the residual stress distribution in the carbon fiber winding layers, which not only easily leads to delamination between fiber layers, but also makes it impossible to timely understand the tension gradient distribution between the winding layers during the carbon fiber winding process, making it impossible to accurately optimize winding process parameters and carbon fiber dosage. Summary of the Invention

[0005] The purpose of the present invention is to provide a type IV hydrogen cylinder stress monitoring system and its signal processing method, and a type IV hydrogen cylinder, which can not only enable the type IV hydrogen cylinder product to have the real-time dynamic monitoring function of the stress between the carbon fiber winding layers and the inner liner stress, and improve the dynamic data monitoring of the stress concentration area of the hydrogen cylinder, but also the type IV hydrogen cylinder stress monitoring system can be used in the processing process of the type IV hydrogen cylinder product to synchronously monitor the residual stress distribution of the carbon fiber winding layer, and timely grasp the tension gradient distribution between each winding layer during the carbon fiber winding process, which is conducive to accurately optimizing the winding process parameters and the carbon fiber dosage to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] In one aspect, the present invention provides a type IV hydrogen cylinder stress monitoring system, comprising:

[0008] A carbon fiber winding layer stress monitoring structure is used to be arranged in the strain generation area of the carbon fiber winding layer, and can dynamically monitor the interlayer stress changes of the carbon fiber winding layer in real time;

[0009] The inner liner stress monitoring structure is used to be arranged in the strain generation area on the outer surface of the plastic inner liner, and can dynamically monitor the stress changes of the plastic inner liner in real time;

[0010] A data processing system is communicatively connected to the carbon fiber winding layer stress monitoring structure and the inner liner stress monitoring structure to collect and process stress collection data of the carbon fiber winding layer stress monitoring structure and the inner liner stress monitoring structure in real time.

[0011] In some embodiments, the carbon fiber winding layer stress monitoring structure is an FBG stress sensor, and the FBG stress sensor includes:

[0012] A substrate, configured to be installed in contact with the carbon fiber winding layer;

[0013] An alloy shell is provided on the upper surface of the substrate, and a portion of the alloy shell is raised, forming an optical fiber channel between the raised portion and the substrate;

[0014] The FBG single-mode optical fiber is movably arranged in the optical fiber channel, and the grid axis of the FBG single-mode optical fiber is parallel to the carbon fiber axis.

[0015] In some embodiments, the inner liner stress monitoring structure adopts the FBG stress sensor that is the same as the carbon fiber winding layer stress monitoring structure, and in the inner liner stress monitoring structure, the substrate is used to be installed in contact with the outer surface of the plastic inner liner, and the grid axis of the FBG single-mode optical fiber is perpendicular to the axis of the plastic inner liner.

[0016] In some embodiments, in any of the FBG stress sensors: the substrate is a copper substrate, the alloy housing is an amorphous zirconium alloy housing, and the cross-section of the protrusion is an arch.

[0017] In some embodiments, in any one of the FBG stress sensors, a plurality of hollow holes are provided on the substrate at intervals along the tensile deformation direction of the FBG single-mode optical fiber.

[0018] On the other hand, the present invention provides a signal processing method for the above-mentioned Type IV hydrogen cylinder stress monitoring system, comprising:

[0019] Step 1: receiving stress monitoring signals from the carbon fiber winding layer stress monitoring structure and / or the liner stress monitoring structure;

[0020] Step 2: performing noise reduction processing on the stress monitoring signal to filter out high-frequency noise signals in the stress monitoring signal and retain medium and low-frequency signals;

[0021] Step 3: Output the stress monitoring signal generated after noise reduction processing.

[0022] In some implementations, the noise reduction method in step 2 includes:

[0023] Step 21, calculate the decomposition layer J:

[0024] According to the energy distribution characteristics of signals and noise at different scales, the decomposition layer J satisfies:

[0025]

[0026] In formula (1), d j is the peak energy of the jth layer, calculated by the amplitude statistics of the detail coefficients;

[0027] 'd j is the noise energy of the jth layer, calculated by the amplitude statistics of the detail coefficient;

[0028] Step 22: Calculate the stratification threshold λ j :

[0029] Each layer threshold λ j Dynamic adjustment based on the statistical characteristics of the wavelet coefficients of this layer:

[0030]

[0031] In formula (2), σ j is the j-th layer noise standard deviation estimate; N j is the length of the j-th layer wavelet coefficient; k j is the adjustment factor, which decreases as the number of decomposition layers increases;

[0032] Step 23: Improve the threshold function:

[0033]

[0034] In formula (3), a is the smoothness coefficient of the control transition zone, and a≥10.

[0035] In another aspect, the present invention provides a Type IV hydrogen cylinder comprising a plastic liner and a carbon fiber winding layer wound around the outside of the plastic liner, and further comprising any one of the above-described Type IV hydrogen cylinder stress monitoring systems, wherein:

[0036] The carbon fiber winding layer stress monitoring structure is provided in the outer surface strain generating area of at least one winding layer of the carbon fiber winding layer;

[0037] The inner liner stress monitoring structure is provided in the strain generating area on the outer surface of the plastic inner liner.

[0038] In some embodiments, the carbon fiber winding layer stress monitoring structure is bonded and fixed to the outer surface of the corresponding winding layer in the carbon fiber winding layer;

[0039] The inner liner stress monitoring structure is bonded and fixed to the outer surface of the plastic inner liner.

[0040] In some embodiments, a plurality of the carbon fiber winding layer stress monitoring structures are provided at intervals along the circumference of the carbon fiber winding layer; and a plurality of the liner stress monitoring structures are provided at intervals along the circumference of the plastic liner.

[0041] Compared with the prior art, the present invention has achieved the following technical effects:

[0042] The Type IV hydrogen cylinder stress monitoring system proposed in the present invention can realize real-time dynamic monitoring of the surface stress of the cylinder liner and the stress between the carbon fiber winding layers by respectively arranging the carbon fiber winding layer stress monitoring structure and the inner liner stress monitoring structure in the strain generation area of the carbon fiber winding layer and the strain generation area of the outer surface of the plastic liner in the Type IV hydrogen cylinder, so that the Type IV hydrogen cylinder product has the real-time dynamic monitoring function of the stress between the carbon fiber winding layers and the inner liner stress.

[0043] The Type IV hydrogen cylinder stress monitoring system of this invention deeply integrates hydrogen cylinder manufacturing processes with real-time monitoring technology. It can be used for both prototype type testing and product integration. While ensuring the safety and reliability of hydrogen cylinders, it can also optimize the structural design of Type IV hydrogen cylinders and improve product performance based on dynamic stress monitoring data. The entire monitoring system is low-cost, stable, and easy to market.

[0044] The signal processing method of the above-mentioned Type IV hydrogen cylinder stress monitoring system proposed in the present invention proposes an improved wavelet threshold noise signal processing method, which can effectively filter high-frequency noise signals and retain medium and low-frequency signals, facilitating the accurate measurement of the surface stress of the carbon fiber winding layer and the plastic liner.

[0045] The proposed Type IV hydrogen cylinder incorporates the carbon fiber winding layer stress monitoring structure and the inner liner stress monitoring structure of the aforementioned Type IV hydrogen cylinder stress monitoring system. This enables real-time dynamic monitoring of the stress between the carbon fiber winding layers and the inner liner stress. While ensuring the safety and reliability of the hydrogen cylinder, the dynamic stress monitoring data can be used to optimize the structural design of the Type IV hydrogen cylinder and enhance its performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0047] Figure 1 This is a schematic diagram of the installation of a Type IV hydrogen cylinder stress monitoring system disclosed in an embodiment of the present invention on a Type IV hydrogen cylinder;

[0048] Figure 2 This is a schematic diagram of the installation of a carbon fiber winding layer stress monitoring structure disclosed in an embodiment of the present invention on a carbon fiber winding layer;

[0049] Figure 3 This is a schematic diagram of the installation of the inner liner stress monitoring structure disclosed in an embodiment of the present invention in a plastic inner liner;

[0050] Figure 4 This is a schematic diagram of the overall structure of the FBG stress sensor disclosed in an embodiment of the present invention;

[0051] Figure 5 This is a schematic diagram of an exploded view of the FBG stress sensor disclosed in an embodiment of the present invention;

[0052] Figure 6 This is a simulated strain cloud diagram of the carbon fiber winding layer disclosed in an embodiment of the present invention at an air pressure of 35 MPa;

[0053] Figure 7 This is a simulated strain cloud diagram of the carbon fiber winding layer disclosed in an embodiment of the present invention at an air pressure of 43 MPa;

[0054] Figure 8 This is a simulated strain cloud diagram of the carbon fiber winding layer disclosed in an embodiment of the present invention at an air pressure of 78 MPa;

[0055] Figure 9 This is a simulated strain cloud diagram of the plastic liner disclosed in an embodiment of the present invention at an air pressure of 35 MPa;

[0056] Figure 10 This is a simulated strain cloud diagram of the plastic liner disclosed in an embodiment of the present invention at an air pressure of 43 MPa;

[0057] Figure 11 This is a simulated strain cloud diagram of the plastic liner disclosed in an embodiment of the present invention at a pressure of 78 MPa;

[0058] Figure 12 A schematic diagram of a method for processing stress signals of a single-mode fiber Bragg grating (FBG) disclosed in an embodiment of the present invention;

[0059] Figure 13 This is a comparison diagram of the stress monitoring signal before and after noise reduction processing disclosed in an embodiment of the present invention.

[0060] In the picture: 100-Ⅳ type hydrogen cylinder:

[0061] 1-carbon fiber winding layer; 11-strain generation area of the winding layer;

[0062] 2-Plastic liner; 21-Strain occurrence area of the liner;

[0063] 3-Carbon fiber winding layer stress monitoring structure;

[0064] 4-Inner tank stress monitoring structure;

[0065] 5-FBG stress sensor; 51-substrate; 511-hollow hole; 52-alloy housing; 521-raised position; 53-optical fiber channel; 54-FBG single-mode optical fiber. DETAILED DESCRIPTION

[0066] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0067] One of the purposes of the present invention is to provide a type IV hydrogen cylinder stress monitoring system. This monitoring system not only enables the type IV hydrogen cylinder product to have the real-time dynamic monitoring function of the stress between the carbon fiber winding layers and the inner liner stress, and improves the dynamic data monitoring of the stress concentration area of the hydrogen cylinder, but also can be used in the processing process of the type IV hydrogen cylinder product to synchronously monitor the residual stress distribution of the carbon fiber winding layer, and timely grasp the tension gradient distribution between the various winding layers during the carbon fiber winding process, which is conducive to accurately optimizing the winding process parameters and the carbon fiber dosage, so as to solve the problems existing in the existing stress monitoring technology.

[0068] Another object of the present invention is to provide a signal processing method for a Type IV hydrogen cylinder stress monitoring system, which can perform noise reduction processing on the stress monitoring signal to filter out high-frequency noise signals in the stress monitoring signal and retain medium and low-frequency signals, thereby facilitating accurate measurement of the surface stress of the carbon fiber winding layer and the plastic liner, and improving the monitoring accuracy of the monitoring system.

[0069] Another object of the present invention is to provide a Type IV hydrogen cylinder, which includes a Type IV hydrogen cylinder stress monitoring system, which has the function of real-time dynamic monitoring of the stress between carbon fiber winding layers and the stress of the inner liner, and can improve the dynamic data monitoring of the stress concentration area of the hydrogen cylinder.

[0070] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0071] Example 1

[0072] like Figures 1 to 3 As shown, this embodiment proposes a type IV hydrogen cylinder stress monitoring system, which mainly includes a carbon fiber winding layer stress monitoring structure 3, an inner liner stress monitoring structure 4 and a data processing system, wherein the carbon fiber winding layer stress monitoring structure 3 is used to be set in the strain generation area of the carbon fiber winding layer 1 in the type IV hydrogen cylinder 100, so as to be able to dynamically monitor the interlayer stress changes of the carbon fiber winding layer 1 in real time; the inner liner stress monitoring structure 4 is used to be set in the strain generation area of the outer surface of the plastic inner liner 2 in the type IV hydrogen cylinder 100, so as to be able to dynamically monitor the stress changes of the plastic inner liner 2 in real time; the data processing system is communicatively connected to both the carbon fiber winding layer stress monitoring structure 3 and the inner liner stress monitoring structure 4 to collect and process the stress collection data of the carbon fiber winding layer stress monitoring structure 3 and the inner liner stress monitoring structure 4 in real time.

[0073] It should be noted that the strain generating area of the aforementioned carbon fiber winding layer 1, i.e., the strain generating area 11 of the winding layer, is not a fixed position area in the gas cylinder, but is simulated based on the strain cloud map calculated by simulation. Moreover, the strain generating area 11 of the winding layer displayed in the strain cloud map calculated by simulation is different at different gas pressures. Figure 6 This is the strain cloud diagram of the carbon fiber winding layer 1 under the simulated calculation of 35MPa pressure. Figure 7 This is the strain cloud diagram of the carbon fiber winding layer 1 under the simulated calculation of 43MPa pressure. Figure 8 This is a simulated strain cloud map of the carbon fiber wrapping layer 1 at 78MPa pressure. The strain occurrence region 11 of the wrapping layer varies slightly in different strain cloud maps. The strain occurrence region 11 of the wrapping layer mainly refers to the dark area between the two ends of the cloud map. Similarly, the strain occurrence region of the plastic liner 2, i.e., the strain occurrence region 12 of the liner, is not a fixed position area in the gas cylinder, but is simulated based on the simulated strain cloud map. Moreover, the strain occurrence region 12 of the liner displayed in the simulated strain cloud map at different pressures is different. Figure 9 This is the strain cloud diagram of the plastic liner 2 under the simulated calculation of 35MPa pressure. Figure 10 This is the strain cloud diagram of the plastic liner 2 under the simulated calculation of 43MPa pressure. Figure 11 This is a strain nephogram of the plastic liner 2 calculated by simulation at an air pressure of 78 MPa. In different strain nephograms, the strain occurrence area 12 of the liner is slightly different. The strain occurrence area 12 of the liner mainly refers to the dark area between the two ends of the nephogram.

[0074] In some feasible implementations, the carbon fiber winding layer stress monitoring structure 3 is preferably a FBG stress sensor 5 (ie, a fiber grating stress sensor), such as Figure 4 As shown, the FBG stress sensor 5 is generally sheet-shaped and suitable for installation between any of the winding layers in the carbon fiber layer 1. It can monitor the tension gradient distribution between the winding layers during the carbon fiber winding process without affecting the winding process. Specifically, the FBG stress sensor 5 comprises a substrate 51, an alloy housing 52, and an FBG single-mode optical fiber 54. The substrate 51 is mounted in contact with the carbon fiber layer 1. The alloy housing 52 is attached to the upper surface of the substrate 51. A local protrusion on the alloy housing 52 forms a raised portion 521, forming an optical fiber channel 53 between the raised portion 521 and the substrate 51. The FBG single-mode optical fiber 54 is movably disposed within the optical fiber channel 53, with the grid axis of the FBG single-mode optical fiber 54 parallel to the axis of the carbon fibers in the carbon fiber layer 1. The carbon fiber axes are generally helically wound around the plastic liner 2, so the carbon fiber axes are not parallel or perpendicular to the axis of the plastic liner 2, but are arranged at an angle to the axis of the plastic liner 2.

[0075] In some feasible implementations, the inner liner stress monitoring structure 4 adopts the same FBG stress sensor 5 as the carbon fiber winding layer stress monitoring structure 3, and the FBG stress sensor 5 serves as the inner liner stress monitoring structure 4, and its substrate 51 is used for installation in contact with the outer surface of the plastic inner liner 2, and the installation angle of the FBG single-mode optical fiber 54 is different from that of the FBG stress sensor 5 serving as the carbon fiber winding layer stress monitoring structure 3, and the grid axis of the FBG single-mode optical fiber 54 of the inner liner stress monitoring structure 4 should be perpendicular to the axis of the plastic inner liner 2.

[0076] In some feasible embodiments, in any FBG stress sensor 5, the substrate 51 is preferably a copper substrate, the alloy housing 52 is preferably an amorphous zirconium alloy housing, the cross-section of the raised portion 521 is preferably arched, specifically, a semicircular groove, and the substrate 51 is provided with a plurality of hollow holes 511 spaced apart along the tensile deformation direction of the FBG single-mode optical fiber 54. The shapes of the hollow holes 511 include, but are not limited to, rectangular, circular, trapezoidal, and flat quadrilateral shapes.

[0077] In some specific embodiments, the amorphous zirconium alloy shell is formed into a thin-walled structure with a wall thickness of 0.05 mm through a cutting process. A central arched raised portion 521 is formed. The inner wall diameter of the raised portion 521 is 0.5 mm. This ensures that the FBG single-mode fiber 54 is not interfered with by the inner wall during tensioning, and provides sufficient strength and rigidity for the FBG single-mode fiber 54. The copper substrate is 0.01 mm thick, 20 mm long, and 10 mm wide. Three equally spaced holes 511 are cut into the central region. Each hole 511 is a 4 mm x 6 mm square hole to relieve tensile deformation of the FBG single-mode fiber 54. The amorphous zirconium alloy shell can be bonded to the upper surface of the copper substrate using epoxy resin glue. The FBG single-mode fiber 54 is threaded between the raised portion 521 and the copper substrate, with both ends extending out of the copper substrate. The FBG single-mode fiber 54 can be bonded to the upper surface of the copper substrate using epoxy resin glue. The epoxy resin glue used above includes but is not limited to 504 type epoxy resin glue.

[0078] The above-mentioned Type IV hydrogen cylinder stress monitoring system is mainly used in the preparation process of Type IV hydrogen cylinder 1, and is embedded in the cylinder after the cylinder is prepared. Figure 1 The type IV hydrogen cylinder 1 shown includes a plastic liner 2 and a carbon fiber winding layer 1 wound around the outside of the plastic liner 2. A carbon fiber winding layer stress monitoring structure 3 is provided in the outer surface strain generation area of at least one winding layer of the carbon fiber winding layer 1; and an inner liner stress monitoring structure 4 is provided in the outer surface strain generation area of the plastic liner 2.

[0079] In some feasible implementations, in order to improve the comprehensiveness of monitoring, it is preferred that, in the carbon fiber winding layer 1, except for the outermost winding layer, the outer surface of any other winding layer is provided with a carbon fiber winding layer stress monitoring structure 3, so that in the finished gas cylinder, the interlayer interval of any carbon fiber winding layer can be dynamically stressed in real time, and the residual stress distribution of the carbon fiber winding layer can be synchronized in time, which is conducive to timely detection of structural damage of the carbon fiber winding layer and avoidance of peeling between fiber layers.

[0080] In some feasible embodiments, the carbon fiber winding layer stress monitoring structure 3 is bonded and fixed to the outer surface of the corresponding winding layer in the carbon fiber winding layer 1. Specifically: the lower surface of the substrate 51 is bonded and fixed to the carbon fiber winding layer 1 by epoxy resin glue, and the bonding position should be as follows: Figures 6 to 8 The strain generating area 11 of the winding layer is shown; it should be noted that the FBG single-mode optical fiber 54 should be pasted according to the direction of the carbon fiber, that is, the grid axis of the FBG single-mode optical fiber 54 should be kept parallel to the carbon fiber axis as much as possible, so as to accurately measure the principal stress of the carbon fiber.

[0081] The structural composition of the liner stress monitoring structure 4 is completely consistent with the carbon fiber winding layer stress monitoring structure 3. The liner stress monitoring structure 4 is preferably bonded to the outer surface of the plastic liner 2. Specifically, the lower surface of the substrate 51 is bonded to the outer surface of the plastic liner 2 by epoxy resin glue. The bonding position should be as follows: Figures 9 to 11 The strain generation area 12 of the inner liner is shown. It should be noted that the attachment angle of the FBG single-mode fiber 54 is different from that of the aforementioned carbon fiber winding layer stress monitoring structure 3. The grid axis of the FBG single-mode fiber 54 of the inner liner stress monitoring structure 4 should be perpendicular to the axis of the plastic inner liner 2. When installing both the carbon fiber winding layer stress monitoring structure 3 and the inner liner stress monitoring structure 4, ensure that the bend radius of the optical fiber is ≥3mm to avoid fiber breakage.

[0082] In some feasible embodiments, multiple carbon fiber layer stress monitoring structures 3 are spaced apart along the circumference of the carbon fiber layer 1; and multiple liner stress monitoring structures 4 are spaced apart along the circumference of the plastic liner 2. As a preferred solution, to avoid mutual interference, the carbon fiber layer stress monitoring structures 3 and the liner stress monitoring structures 4 are staggered around the cylinder to avoid overlapping monitoring areas.

[0083] The data processing system of the above-mentioned Type IV hydrogen cylinder stress monitoring system can be a conventional product system in this field, such as Figure 12 As shown, the system includes a circulator, a broadband light source, a matched grating, and a photodetector. The photodetector primarily receives fiber optic signals from the carbon fiber wrapping layer stress monitoring structure 3 and the inner liner stress monitoring structure 4. After receiving the fiber optic signals, the photodetector uses improved wavelet threshold noise signal processing technology to reduce noise. The core of this improved wavelet threshold noise signal processing is a layered adaptive wavelet threshold denoising algorithm. As the IV hydrogen cylinder jolts during vehicle operation, it generates high-frequency noise signals. These broadband signals require layered filtering while retaining the mid- and low-frequency strain signals from the cylinder liner and carbon fiber wrapping layer to ensure the validity of the FBG grating signal.

[0084] In summary, the Type IV hydrogen cylinder stress monitoring system of the present invention realizes real-time dynamic monitoring of the surface stress of the cylinder liner and the stress between the carbon fiber winding layers through the embedded FBG stress sensor, so that the Type IV hydrogen cylinder product has the real-time dynamic monitoring function of the stress between the carbon fiber winding layers and the inner liner stress.

[0085] The core benefit of this invention lies in its deep integration of hydrogen cylinder manufacturing processes and real-time monitoring technology. This technology can be used for both prototype type testing and product integration. While ensuring the safety and reliability of hydrogen cylinders, it can also optimize the structural design of Type IV hydrogen cylinders based on dynamic stress monitoring data, improving product performance. The entire product is low-cost, stable, and easy to market.

[0086] An amorphous zirconium alloy housing encapsulates the FBG fiber Bragg grating (FBG) into an integrated device. Due to the high hardness, strength, and ductility of amorphous zirconium alloy, even with a wall thickness of only 0.05mm, the device maintains strength while maintaining a certain degree of deformation resistance. This prevents the tension of the carbon fiber layer from causing the housing to break, affecting the measurement accuracy of the FBG or damaging the grating. This FBG fiber sensor integrated device can be flexibly arranged into the desired carbon fiber layer and attached according to the winding direction to accurately measure the principal stress of the carbon fiber filaments.

[0087] The proposed improved wavelet threshold noise signal processing method can effectively filter high-frequency noise signals and retain medium and low-frequency signals, which facilitates the accurate measurement of the surface stress of the carbon fiber winding layer and the plastic liner.

[0088] Example 2

[0089] This embodiment provides a signal processing method for the above-mentioned Type IV hydrogen cylinder stress monitoring system, including:

[0090] Step 1: receiving stress monitoring signals from the carbon fiber winding layer stress monitoring structure 3 and / or the liner stress monitoring structure 4;

[0091] Step 2: noise reduction processing is performed on the stress monitoring signal to filter out high-frequency noise signals in the stress monitoring signal and retain medium and low-frequency signals;

[0092] Step 3: Output the stress monitoring signal generated after noise reduction processing.

[0093] In some feasible implementations, the noise reduction processing method in step 2 includes:

[0094] Step 21, calculate the decomposition layer J:

[0095] According to the energy distribution characteristics of signals and noise at different scales, the decomposition layer J satisfies:

[0096]

[0097] In formula (1), d j is the peak energy of the jth layer, calculated by the amplitude statistics of the detail coefficients;

[0098] 'd j is the noise energy of the jth layer, calculated by the amplitude statistics of the detail coefficient;

[0099] Step 22: Calculate the stratification threshold λ j :

[0100] Each layer threshold λ j Dynamic adjustment based on the statistical characteristics of the wavelet coefficients of this layer:

[0101]

[0102] In formula (2), σ j is the j-th layer noise standard deviation estimate; N j is the length of the j-th layer wavelet coefficient; k j is the adjustment factor, which decreases as the number of decomposition layers increases;

[0103] Step 23: Improve the threshold function:

[0104]

[0105] In formula (3), a is the smoothness coefficient of the control transition zone, and a≥10.

[0106] The above improved wavelet threshold noise signal processing procedure can be as follows:

[0107] load noisbloc;

[0108] signal=noisbloc;

[0109] % Wavelet decomposition (number of layers = 5, wavelet basis = 'sym8')

[0110] [c,l]=wavedec(signal,5,'sym8');

[0111] % Layered adaptive threshold

[0112] alpha=[3.0,2.5,2.0,1.5,1.0]; %Threshold coefficients for different layers

[0113] for i=1:5

[0114] thr=alpha(i)*median(abs(c(detcoef(c,l,i)))); % Adaptive threshold based on median

[0115] c=wthresh(c,'s',thr,i); %Soft threshold processing specified layer

[0116] end

[0117] %Reconstructed signal

[0118] denoised_signal=waverec(c,l,'sym8');

[0119] % Drawing comparison

[0120] figure;

[0121] subplot(3,1,1); plot(signal); title('Original noisy signal');

[0122] subplot(3,1,3); plot(noisbloc-denoised_signal); title('Signal after noise removal').

[0123] The signal processing method for the Type IV hydrogen cylinder stress monitoring system of the present invention proposes an innovative stress signal processing method, namely, an improved wavelet threshold noise signal processing method. The core of this improved wavelet threshold noise signal processing method is a layered adaptive wavelet threshold denoising algorithm. As the Type IV hydrogen cylinder vibrates during vehicle operation, it generates high-frequency noise signals. These broadband signals require layered filtering while retaining the mid- and low-frequency strain signals of the cylinder liner and carbon fiber wrapping. This ensures the validity of the FBG grating signal and facilitates accurate measurement of the surface stress of the carbon fiber wrapping and plastic liner.

[0124] Example 3

[0125] like Figure 1 As shown, this embodiment proposes a Type IV hydrogen cylinder 100, comprising a plastic liner 2 and a carbon fiber winding layer 1 wound around the outside of the plastic liner 2, and also comprising the Type IV hydrogen cylinder stress monitoring system of Example 1, wherein: a carbon fiber winding layer stress monitoring structure 3 is provided in the outer surface strain generating area of at least one winding layer in the carbon fiber winding layer 1; and a liner stress monitoring structure 4 is provided in the outer surface strain generating area of the plastic liner 2.

[0126] In some feasible implementations, in order to improve the comprehensiveness of monitoring, it is preferred that, in the carbon fiber winding layer 1, except for the outermost winding layer, the outer surface of any other winding layer is provided with a carbon fiber winding layer stress monitoring structure 3, so that in the finished gas cylinder, the interlayer interval of any carbon fiber winding layer can be dynamically stressed in real time, and the residual stress distribution of the carbon fiber winding layer can be synchronized in time, which is conducive to timely detection of structural damage of the carbon fiber winding layer and avoidance of peeling between fiber layers.

[0127] In some feasible implementations, the carbon fiber winding layer stress monitoring structure 3 is bonded and fixed to the outer surface of the corresponding winding layer in the carbon fiber winding layer 1 ; the liner stress monitoring structure 4 is bonded and fixed to the outer surface of the plastic liner 2 .

[0128] In some feasible embodiments, multiple carbon fiber layer stress monitoring structures 3 are spaced apart along the circumference of the carbon fiber layer 1; and multiple liner stress monitoring structures 4 are spaced apart along the circumference of the plastic liner 2. As a preferred solution, to avoid mutual interference, the carbon fiber layer stress monitoring structures 3 and the liner stress monitoring structures 4 are staggered around the cylinder to avoid overlapping monitoring areas.

[0129] The Type IV hydrogen cylinder 100 of the present invention utilizes embedded FBG stress sensors to dynamically monitor the surface stress of the cylinder liner and the stress between carbon fiber winding layers. This provides the Type IV hydrogen cylinder with real-time dynamic monitoring of both the stress between carbon fiber winding layers and the liner stress. While ensuring the safety and reliability of the hydrogen cylinder, the dynamic stress monitoring data can also be used to optimize the structural design of the Type IV hydrogen cylinder and enhance its performance.

[0130] It should be noted that the structures, proportions, sizes, etc. depicted in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions for the implementation of the present invention. Therefore, they have no substantial technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose of the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0131] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A type IV hydrogen cylinder stress monitoring system, characterized in that: include: A carbon fiber winding layer stress monitoring structure is used to be arranged in the strain generation area of the carbon fiber winding layer, and can dynamically monitor the interlayer stress changes of the carbon fiber winding layer in real time; The inner liner stress monitoring structure is used to be arranged in the strain generation area on the outer surface of the plastic inner liner, and can dynamically monitor the stress changes of the plastic inner liner in real time; A data processing system is communicatively connected to the carbon fiber winding layer stress monitoring structure and the inner liner stress monitoring structure to collect and process stress collection data of the carbon fiber winding layer stress monitoring structure and the inner liner stress monitoring structure in real time.

2. The type IV hydrogen cylinder stress monitoring system according to claim 1, characterized in that: The carbon fiber winding layer stress monitoring structure is an FBG stress sensor, and the FBG stress sensor includes: A substrate, used for contacting and mounting with the carbon fiber winding layer; An alloy shell is provided on the upper surface of the substrate, and a portion of the alloy shell is raised, forming an optical fiber channel between the raised portion and the substrate; The FBG single-mode optical fiber is movably arranged in the optical fiber channel, and the grid axis of the FBG single-mode optical fiber is parallel to the carbon fiber axis.

3. The type IV hydrogen cylinder stress monitoring system according to claim 2, characterized in that: The inner liner stress monitoring structure adopts the FBG stress sensor that is the same as the carbon fiber winding layer stress monitoring structure, and in the inner liner stress monitoring structure, the substrate is used for contact installation with the outer surface of the plastic inner liner, and the grid axis of the FBG single-mode optical fiber is perpendicular to the axis of the plastic inner liner.

4. The type IV hydrogen cylinder stress monitoring system according to claim 3, characterized in that: In any of the FBG stress sensors, the substrate is a copper substrate, the alloy shell is an amorphous zirconium alloy shell, and the cross section of the protrusion is an arch.

5. The type IV hydrogen cylinder stress monitoring system according to claim 3, characterized in that: In any one of the FBG stress sensors, a plurality of hollow holes are provided on the substrate at intervals along the tensile deformation direction of the FBG single-mode optical fiber.

6. A signal processing method for a type IV hydrogen cylinder stress monitoring system according to any one of claims 2 to 5, characterized in that: include: Step 1: receiving stress monitoring signals from the carbon fiber winding layer stress monitoring structure and / or the liner stress monitoring structure; Step 2: performing noise reduction processing on the stress monitoring signal to filter out high-frequency noise signals in the stress monitoring signal and retain medium and low-frequency signals; Step 3: Output the stress monitoring signal generated after noise reduction processing.

7. The type IV hydrogen cylinder stress monitoring system according to claim 6, characterized in that: The noise reduction processing method in step 2 includes: Step 21, calculate the decomposition layer J: According to the energy distribution characteristics of signals and noise at different scales, the decomposition layer J satisfies: In formula (1), d j is the peak energy of the jth layer, calculated by the amplitude statistics of the detail coefficients; 'd j is the noise energy of the jth layer, calculated by the statistical value of the detail coefficient amplitude; Step 22: Calculate the stratification threshold λ j : Each layer threshold λ j Dynamic adjustment based on the statistical characteristics of the wavelet coefficients of this layer: In formula (2), σ j N is the j-th layer noise standard deviation estimate; j is the length of the j-th layer wavelet coefficient; k j is the adjustment factor, which decreases as the number of decomposition layers increases; Step 23: Improve the threshold function: In formula (3), a is the smoothness coefficient of the control transition zone, and a≥10.

8. A type IV hydrogen cylinder comprising a plastic liner and a carbon fiber winding layer wound around the outside of the plastic liner, characterized in that: It also includes the Type IV hydrogen cylinder stress monitoring system according to any one of claims 1 to 5, wherein: The carbon fiber winding layer stress monitoring structure is provided in the outer surface strain generating area of at least one winding layer of the carbon fiber winding layer; The inner liner stress monitoring structure is provided in the strain generating area on the outer surface of the plastic inner liner.

9. The type IV hydrogen cylinder according to claim 8, characterized in that: The carbon fiber winding layer stress monitoring structure is bonded and fixed to the outer surface of the corresponding winding layer in the carbon fiber winding layer; The inner liner stress monitoring structure is bonded and fixed to the outer surface of the plastic inner liner.

10. The type IV hydrogen cylinder according to claim 8, characterized in that: A plurality of carbon fiber winding layer stress monitoring structures are arranged at intervals along the circumference of the carbon fiber winding layer; and a plurality of liner stress monitoring structures are arranged at intervals along the circumference of the plastic liner.

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