Marine diesel engine cylinder sleeve surface deformation measurement method based on fiber grating acceleration sensor

Abstract

The invention provides a marine diesel engine cylinder sleeve surface deformation measuring method based on a fiber grating acceleration sensor. According to the method, a low-frequency and high-sensitivity fiber bragg grating acceleration sensor is installed outside a cylinder sleeve, the surface vibration of the cylinder sleeve is measured, fiber bragg grating deformation of the sensor is caused, wavelength drifts, an obtained optical signal is converted into an electric signal, filtering, amplification, noise reduction and other processing are carried out, and the vibration acceleration of the surface of the cylinder sleeve is measured. The vibration frequency component and amplitude are determined through spectral analysis, and the surface deformation condition is obtained by converting the acceleration into the speed through integral operation and then converting the speed into the displacement. Compared with a traditional mode of measuring deformation by using a strain gauge, the method is high in anti-interference capability, high in sensitivity and good in durability, can realize distributed measurement, and has the advantage of temperature supplementation.

Description

Technical Field

[0001] The invention belongs to the technical field of cylinder liner surface deformation measurement, and in particular relates to a method for measuring the surface deformation of a ship diesel engine cylinder liner based on a fiber grating acceleration sensor. Background Art

[0002] In the field of engines, the study of cylinder liner deformation is of vital importance. Cylinder liner deformation is usually predicted by finite element analysis. However, since it is the result of multi-physics field coupling, many influencing factors and differences in modeling simplification and analysis assumptions will affect the accuracy of the calculation results. Therefore, the test and analysis of cylinder liner deformation is indispensable, which can provide accurate boundary conditions for calculation and correct the finite element analysis model.

[0003] Cylinder liner deformation testing has always been difficult, especially the dynamic working deformation testing. Usually, cylinder liner deformation data is mostly obtained by actual measurement in static state after the engine assembly and operation. Domestic and foreign engine manufacturers often use three-dimensional measuring instruments for static deformation testing. Although it can understand the processing and manufacturing tolerances, evaluate the influence of bolt preload, and the thermal deformation caused by different materials and working temperatures, this method is carried out under the static state of the engine, ignoring the temperature difference of components caused by combustion and the mechanical load caused by gas pressure.

[0004] Moreover, precision measuring instruments are expensive and can only measure static data. For engines in working condition, the dynamic deformation research of cylinder liners mainly relies on eddy current sensors, strain gauge sensors, etc. However, these traditional methods have many limitations.

[0005] In this context, the surface deformation measurement method of the ship diesel engine cylinder liner based on fiber Bragg grating accelerometer has shown significant advantages. It has high sensitivity and can measure smaller strains. Compared with traditional strain gauges and other methods, it performs better in measurement accuracy and the ability to capture small deformations. Summary of the invention

[0006] The purpose of the present invention is to solve the problems in the prior art and propose a method for measuring the surface deformation of a cylinder liner of a marine diesel engine based on a fiber grating acceleration sensor.

[0007] The present invention is realized by the following technical scheme. The present invention proposes a method for measuring the surface deformation of a cylinder liner of a marine diesel engine based on a fiber grating acceleration sensor. The method is specifically as follows:

[0008] Several low-frequency and high-sensitivity fiber grating acceleration sensors are installed on the outside of the cylinder liner. By measuring the vibration acceleration of the cylinder liner surface, the optical signal is converted into an electrical signal, which is filtered, amplified and noise-reduced. The vibration frequency component and amplitude are determined by spectrum analysis. The acceleration is converted into velocity and then into displacement through integral operation to obtain the surface deformation of the cylinder liner.

[0009] Furthermore, the fiber Bragg grating acceleration sensor is accurately and firmly installed on the surface of the cylinder liner. When the diesel engine is running, the surface of the cylinder liner vibrates due to the piston movement and the combustion process, and the vibration is transmitted to the fiber Bragg grating acceleration sensor. The mass block and cantilever beam of the fiber Bragg grating acceleration sensor vibrate, driving the upper and lower fiber Bragg gratings to produce expansion and contraction deformation, thereby causing the reflection wavelength of the fiber Bragg grating to drift.

[0010] Furthermore, the relationship between the change in the central wavelength, i.e., the wavelength drift, and the acceleration is obtained by demodulating the change in the central wavelength with a fiber optic demodulator. The fiber grating acceleration sensor detects vibration and converts the acceleration signal into a change in the wavelength of an optical signal through a fiber optic demodulator, thereby transmitting the wavelength change to a computer for processing.

[0011] Furthermore, the electrical signal obtained after computer processing is filtered, amplified and noise-reduced, and the vibration frequency component and amplitude are determined by spectrum analysis. The acceleration signal is converted into velocity and then into displacement signal through integration operation. The deformation of the cylinder liner surface is calculated based on the displacement signal combined with the geometric shape and mechanical properties of the cylinder liner.

[0012] Furthermore, fiber Bragg grating acceleration sensors with different sensitivities are designed according to different cylinder liner measurement requirements, specifically:

[0013] The displacement caused by strain at any position on the cylinder sleeve is understood and analyzed as a sine function with a specific rule. The expression of the sine function is:

[0014] x=Asin(2πft)

[0015] The sine function is differentiated twice to obtain its acceleration a:

[0016] a=A(2πf) 2 sin(2πft)

[0017] Where A is the amplitude equal to the radius change Δr, when the circumference change of the cylinder sleeve is Δl, the radius change is Δr, and frequency cycle n is the crankshaft speed;

[0018] Then, by using the resolution p of the fiber optic interrogator and substituting it into the sensitivity calculation formula, the required sensor sensitivity k can be obtained.

[0019] Furthermore, the sensitivity calculation formula is:

[0020]

[0021] Furthermore, the surface of the diesel engine cylinder liner is arranged in 6 columns and 4 rows of sensors.

[0022] Furthermore, each row of sensors is connected to a fiber optic demodulator to measure a wavelength drift signal. The fiber optic demodulator is connected to a computer. The wavelength drift is processed on the computer. The measured acceleration data is obtained based on the relationship between acceleration and vibration frequency obtained by calibration of a standard accelerometer. The measured acceleration data is integrated by a computer to obtain displacement data, that is, the cylinder liner surface deformation data.

[0023] The present invention also proposes an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the method for measuring the surface deformation of a ship diesel engine cylinder liner based on a fiber grating acceleration sensor are implemented.

[0024] The present invention also proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of a method for measuring the surface deformation of a cylinder liner of a marine diesel engine based on a fiber grating acceleration sensor.

[0025] Compared with the existing traditional strain gauge technology, the fiber grating acceleration sensor measurement method of the present invention has the following advantages:

[0026] 1. Strong anti-interference ability: The optical signal transmitted by optical fiber is not subject to electromagnetic interference, which can solve the problem that traditional strain gauges are susceptible to electromagnetic interference and cause measurement errors, ensuring the accuracy of the measurement results.

[0027] 2. High sensitivity: Especially the low-frequency and high-sensitivity characteristics can more accurately detect small vibration acceleration changes, which makes up for the shortcomings of traditional strain gauges in capturing subtle surface deformation characteristics.

[0028] 3. Good durability: Fiber optic materials are corrosion-resistant and wear-resistant, and can work stably for a long time in harsh environments. Traditional strain gauges may be affected by environmental factors, resulting in unstable measurement results.

[0029] 4. Distributed measurement capability: It can obtain vibration information at multiple locations at the same time and fully understand the deformation condition of the cylinder liner surface. Traditional strain gauges can usually only measure a single point and cannot provide the overall deformation condition.

[0030] 5. Advantages of long-distance transmission: The optical signal has little attenuation during long-distance transmission, which is convenient for data collection and processing. The electrical signal of traditional strain gauges is prone to loss and interference during long-distance transmission, which affects the data quality.

[0031] 6. Easy installation: It is relatively simple to install on the outside of the cylinder sleeve, without the need for complicated pasting processes and high-precision surface treatment, which solves the problems of cumbersome installation and difficult calibration of traditional strain gauges.

[0032] 7. Excellent temperature compensation: Insensitive to temperature changes or able to effectively compensate, reducing the impact of temperature on measurement results. The problem of large deviation in measurement results of traditional strain gauges in environments with large temperature changes is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0034] Figure 1 This is a schematic diagram of the fiber Bragg grating acceleration sensor of the present invention being installed on the surface of a cylinder sleeve.

[0035] Figure 2 This is the structural diagram of the standard accelerometer calibration system.

[0036] Figure 3 The present invention is a flow chart of a method for measuring the surface deformation of a cylinder liner of a marine diesel engine based on a fiber grating acceleration sensor.

[0037] Figure 4 This is a structural diagram of the measurement system used in the method described in the present invention. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0039] Combination Figure 1-Figure 4 The present invention proposes a method for measuring the surface deformation of a cylinder liner of a marine diesel engine based on a fiber grating acceleration sensor, and the method is specifically as follows:

[0040] Several low-frequency and highly sensitive fiber Bragg grating acceleration sensors are installed on the outside of the cylinder liner, and the surface of the diesel engine cylinder liner is arranged in 6 rows and 4 columns of sensors; by measuring the vibration acceleration of the cylinder liner surface, the optical signal is converted into an electrical signal, filtered, amplified and noise-reduced, and the vibration frequency component and amplitude are determined by spectrum analysis, and the acceleration is converted into velocity and then displacement by integral operation to obtain the deformation of the cylinder liner surface. The method has higher accuracy and can measure smaller deformation.

[0041] The fiber Bragg grating accelerometer is accurately and firmly installed on the surface of the cylinder liner. When the diesel engine is running, the surface of the cylinder liner vibrates due to the piston movement and the combustion process, and the vibration is transmitted to the fiber Bragg grating accelerometer. The mass block and cantilever beam of the fiber Bragg grating accelerometer vibrate, driving the upper and lower fiber Bragg gratings to produce expansion and contraction deformation, thereby causing the reflection wavelength of the fiber Bragg grating to drift.

[0042] The change of the central wavelength is demodulated by a fiber optic demodulator to obtain the relationship between the central wavelength change, that is, the wavelength drift, and acceleration. The fiber grating acceleration sensor detects vibration and converts the acceleration signal into a light signal wavelength change through a fiber optic demodulator, thereby transmitting the wavelength change to a computer for processing.

[0043] The electrical signal obtained after computer processing is filtered, amplified and noise-reduced, and the vibration frequency component and amplitude are determined by spectrum analysis. The acceleration signal is converted into velocity and then displacement signal through integration operation. This process must consider factors such as sensor installation method, cylinder liner structural characteristics and material properties, and make corrections and compensations. Finally, the deformation of the cylinder liner surface is calculated based on the displacement signal combined with the cylinder liner geometry and mechanical properties. The results are compared and verified with other measurement methods to evaluate accuracy and reliability.

[0044] Fiber Bragg grating acceleration sensors with different sensitivities are designed according to different cylinder liner measurement requirements, specifically:

[0045] The displacement caused by strain at any position on the cylinder sleeve is understood and analyzed as a sine function with a specific rule. The expression of the sine function is:

[0046] x=Asin(2πft)

[0047] The sine function is differentiated twice to obtain its acceleration a:

[0048] a=A(2πf) 2 sin(2πft)

[0049] Where A is the amplitude equal to the radius change Δr, when the circumference change of the cylinder sleeve is Δl, the radius change is Δr, and The acceleration calculated when the circumference changes by Δl is a; the frequency of the sine function is The gas pressure changes as a sinusoidal function, and its fluctuation range is (-90°--130°), accounting for % of the crankshaft motion cycle (360°). The crankshaft speed is nr / min, so the time for the crankshaft to rotate once is 60 / ns, which is the period of the sine function. n is the crankshaft speed;

[0050] Then, by using the resolution p of the fiber optic interrogator and substituting it into the sensitivity calculation formula, the required sensor sensitivity k can be obtained.

[0051] The sensitivity calculation formula is:

[0052]

[0053] Calibration is required before measurement. The instruments used in the experiment include standard accelerometer, signal output device, power amplifier, vibration platform, fiber Bragg grating acceleration sensor, demodulator, etc. The standard accelerometer and fiber Bragg grating acceleration sensor are installed on the vibration platform. By changing the input power, the relationship between acceleration is obtained to achieve the calibration purpose.

[0054] Each row of sensors is connected to a fiber optic demodulator to measure the wavelength drift signal. The fiber optic demodulator is connected to a computer. The wavelength drift is processed on the computer. The measured acceleration data is obtained based on the relationship between acceleration and vibration frequency obtained by calibration of a standard accelerometer. The measured acceleration data is integrated by a computer to obtain displacement data, that is, the deformation data of the cylinder liner surface.

[0055] The present invention proposes a method for measuring the surface deformation of a cylinder liner of a marine diesel engine based on a fiber grating acceleration sensor, and the operation steps are as follows:

[0056] Step 1: Disassemble the engine to be tested, install 4 rows and 6 columns of designed fiber grating acceleration sensors on the outside of the cylinder liner, connect the end of the sensor to the fiber optic demodulator, and connect the demodulator to the computer.

[0057] Step 2: After disassembling the engine, complete the process in step 1 and then assemble the engine.

[0058] Step 3: Start the engine, let it run normally, and power on the electrical appliances involved in the experiment.

[0059] Step 4: The fiber Bragg grating acceleration sensor tests the real-time dynamic deformation of the engine cylinder liner, and the data is processed by a computer and displayed on the display screen.

[0060] Step 5: The experimenter observes the fitting graph and records and analyzes the experimental data.

[0061] Step 6: After the test is completed, turn off all electrical equipment and repeat the above steps for the next test.

[0062] The present invention relates to a method for measuring surface deformation by measuring the vibration acceleration of the cylinder liner surface using an optical fiber acceleration sensor, which aims to install a low-frequency and high-sensitivity optical fiber acceleration sensor on the outside of the cylinder liner, measure the vibration acceleration of the cylinder liner surface, cause the fiber grating of the sensor to deform and cause the wavelength to drift, convert the obtained optical signal into an electrical signal, perform filtering, amplification, noise reduction and other processing, determine the vibration frequency component and amplitude by spectrum analysis, convert acceleration into velocity and then displacement by integral operation to obtain the surface deformation. This is a brand-new method, compared with the traditional method of measuring deformation with strain gauges, it has strong anti-interference ability, high sensitivity, good durability, can realize distributed measurement, and has the advantage of temperature supplement.

[0063] The present invention also proposes an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the method for measuring the surface deformation of a ship diesel engine cylinder liner based on a fiber grating acceleration sensor are implemented.

[0064] The present invention also proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of a method for measuring the surface deformation of a cylinder liner of a marine diesel engine based on a fiber grating acceleration sensor.

[0065] The memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM bus RAM (DRRAM). It should be noted that the memory of the method described in the present invention is intended to include, but is not limited to, these and any other suitable types of memory.

[0066] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a high-density digital video disc (DVD)), or a semiconductor medium (eg, a solid state disc (SSD)).

[0067] In the implementation process, each step of the above method can be completed by an integrated logic circuit of hardware in a processor or an instruction in the form of software. The steps of the method disclosed in conjunction with the embodiment of the present application can be directly embodied as a hardware processor for execution, or a combination of hardware and software modules in a processor for execution. The software module can be located in a storage medium mature in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor reads the information in the memory and completes the steps of the above method in conjunction with its hardware. To avoid repetition, it is not described in detail here.

[0068] It should be noted that the processor in the embodiment of the present application can be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method embodiment can be completed by an integrated logic circuit of hardware in the processor or an instruction in the form of software. The above processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiment of the present application can be directly embodied as a hardware decoding processor to perform, or the hardware and software modules in the decoding processor can be combined and performed. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0069] The above is a detailed introduction to the surface deformation measurement method of the ship diesel engine cylinder liner based on the fiber Bragg grating acceleration sensor proposed in the present invention. The principle and implementation mode of the present invention are explained in detail by using specific examples. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for measuring the surface deformation of a ship diesel engine cylinder liner based on a fiber grating acceleration sensor, characterized in that: The method is specifically as follows: Several low-frequency and high-sensitivity fiber grating acceleration sensors are installed on the outside of the cylinder liner. By measuring the vibration acceleration of the cylinder liner surface, the optical signal is converted into an electrical signal, which is filtered, amplified and noise-reduced. The vibration frequency component and amplitude are determined by spectrum analysis. The acceleration is converted into velocity and then into displacement through integral operation to obtain the surface deformation of the cylinder liner.

2. The method according to claim 1, characterized in that The fiber Bragg grating accelerometer is accurately and firmly installed on the surface of the cylinder liner. When the diesel engine is running, the surface of the cylinder liner vibrates due to the piston movement and the combustion process, and the vibration is transmitted to the fiber Bragg grating accelerometer. The mass block and cantilever beam of the fiber Bragg grating accelerometer vibrate, driving the upper and lower fiber Bragg gratings to produce expansion and contraction deformation, thereby causing the reflection wavelength of the fiber Bragg grating to drift.

3. The method according to claim 2, characterized in that The change of the central wavelength is demodulated by a fiber optic demodulator to obtain the relationship between the central wavelength change, that is, the wavelength drift, and acceleration. The fiber grating acceleration sensor detects vibration and converts the acceleration signal into a light signal wavelength change through a fiber optic demodulator, thereby transmitting the wavelength change to a computer for processing.

4. The method according to claim 3, characterized in that The electrical signal obtained after computer processing is filtered, amplified and noise-reduced, and the vibration frequency component and amplitude are determined by spectrum analysis. The acceleration signal is converted into velocity and then into displacement signal through integration operation. The deformation of the cylinder liner surface is calculated based on the displacement signal combined with the geometric shape and mechanical properties of the cylinder liner.

5. The method according to claim 1, characterized in that Fiber Bragg grating acceleration sensors with different sensitivities are designed according to different cylinder liner measurement requirements, specifically: The displacement caused by strain at any position on the cylinder sleeve is understood and analyzed as a sine function with a specific rule. The expression of the sine function is: x=Asin(2πft) The sine function is differentiated twice to obtain its acceleration a: a=A(2πf) 2 sin(2πft) Where A is the amplitude equal to the radius change Δr, when the circumference change of the cylinder sleeve is Δl, the radius change is Δr, and frequency cycle n is the crankshaft speed; Then, by using the resolution p of the fiber optic interrogator and substituting it into the sensitivity calculation formula, the required sensor sensitivity k can be obtained.

6. The method according to claim 5, characterized in that The sensitivity calculation formula is:

7. The method according to claim 1, characterized in that The surface of the diesel engine cylinder liner is arranged in 6 rows and 4 columns of sensors.

8. The method according to claim 1, characterized in that Each row of sensors is connected to a fiber optic demodulator to measure the wavelength drift signal. The fiber optic demodulator is connected to a computer. The wavelength drift is processed on the computer. The measured acceleration data is obtained based on the relationship between acceleration and vibration frequency obtained by calibration of a standard accelerometer. The measured acceleration data is integrated by a computer to obtain displacement data, that is, the deformation data of the cylinder liner surface.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium for storing computer instructions, characterized in that: When the computer instructions are executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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