High-pressure oil filter sealing structure improvement method based on finite element simulation analysis

Abstract

The invention relates to the technical field of high-pressure oil filter repair, in particular to a high-pressure oil filter sealing structure improvement method based on finite element simulation analysis, which comprises the following steps: step 1, analyzing damage failure of a sealing ring of a high-pressure oil filter filler neck; 2, analyzing the stress of the threads of the high-pressure oil filter filler neck; 3, performing finite element simulation on threaded connection of the filler neck and the shell; 4, performing finite element simulation on the damage of the high-pressure oil filter sealing ring, and establishing a simulation model; 5, researching a filler neck structure improvement method; and step 6, establishing a filler neck sealing structure for improvement test verification. The high-pressure oil filter filler neck solves the problem that the high-pressure oil filter filler neck is squeezed out of a gap of the sealing ring for a long time to cause oil leakage, and meets the use requirement for reliable service life cycle of products. And in the product repairing process, fluoroplastic gaskets with different thicknesses are selected and matched to fill the gap between the shell and the filler neck, so that the repairing quality and the use reliability of the product are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of high-pressure oil filter repair, and in particular to a method for improving a high-pressure oil filter sealing structure based on finite element simulation analysis. Background Art

[0002] The high-pressure oil filter is an important component in the aircraft hydraulic system. It is used to filter solid particles in the aircraft hydraulic system pipeline to prevent damage caused by pollutants in the system. When the system is polluted, the anti-pulse pressure difference signal device sends an indication signal to remind the flight personnel. Ground inspections have repeatedly found that the joint between the high-pressure hydraulic oil filter connector and the oil filter top cover has black debris-like deposits, that is, the damaged and extruded part of the sealing ring, which poses a safety hazard of leakage. This fault has a high incidence of problems and the replacement of the sealing ring cannot eliminate the damage, which affects customer satisfaction and consumes a lot of time and energy for maintenance. Therefore, it is necessary to carry out research on the prevention technology of the sealing ring damage of the take-over nozzle as soon as possible, improve the product repair quality, enhance the maintenance and support capabilities of aviation equipment, and achieve the purpose of preventing major failures. The present invention provides a method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis, so as to fundamentally solve the sealing ring damage and leakage failure that occurs during the use of the main high-pressure oil filter, and improve product quality and reliability. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis.

[0004] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0005] A method for improving a high-pressure oil filter sealing structure based on finite element simulation analysis comprises the following steps:

[0006] Step 1: Failure analysis of the high-pressure oil filter nozzle seal ring damage:

[0007] Conduct failure analysis on the damage of the nozzle seal ring and preliminarily determine the cause of the seal failure;

[0008] Step 2: Force analysis of high pressure oil filter nozzle thread:

[0009] The Yamamoto function method is used to study the load distribution of the thread during the assembly and pressure supply of the high-pressure oil filter nozzle, calculate the change of the gap between the nozzle and the shell installation end face, and obtain the relationship between the nozzle tightening torque and preload.

[0010] Step 3: Finite element simulation of the threaded connection between the butt nozzle and the shell:

[0011] The threaded connection structure between the nozzle and the shell was parametrically modeled, and the finite element analysis of the nozzle thread during pressure supply was carried out to verify the consistency between the end face clearance value obtained by simulation analysis and the value calculated by function theory;

[0012] Step 4: Finite element simulation of high-pressure oil filter seal damage and establishment of simulation model:

[0013] In view of the fact that the O-ring is an axisymmetric structure, an axisymmetric two-dimensional model is used to analyze the sealing ring. The nozzle and the oil filter housing are simplified, and the structure of the contact part with the sealing ring is retained. The various components are meshed, and a mesh simulation model of the sealing ring is established. The equivalent stress and appearance deformation of the sealing ring in three states, after assembly, when supplying pressure, and after pressure relief, are simulated and analyzed.

[0014] Step 5: Study the method of improving the nozzle structure:

[0015] Based on the above force analysis, in order to change the end face clearance between the nozzle and the upper shell and reduce the possibility of the seal ring being squeezed in, according to the aircraft hydraulic system design margin standard, when the actual product end face clearance can reach a maximum of 0.1mm, it is necessary to improve it by at least 1.5 times the maximum clearance and fill it by adding a fluoroplastic gasket;

[0016] Step 6: Build test verification for improvement of nozzle sealing structure:

[0017] A pressure pulse test device is designed, and a pressure shock test is used to detect the pressure resistance and impact resistance of the test piece. This step is repeated to simulate the product in an extreme working environment to verify the product reliability. After the pressure shock test, a low-pressure sealing test and a high-pressure sealing test are carried out, and the appearance of the product's matching take-over nozzle is checked and the product's matching take-over nozzle is disassembled for inspection.

[0018] As a further improvement of the present invention, the failure analysis of the damage to the nozzle seal ring in step 1 includes: macro inspection, micro observation, hardness analysis, gap measurement, combined with common failure form characteristics of O-rings and stress analysis of the nozzle seal ring.

[0019] As a further improvement of the present invention, step 2 includes thread force analysis when the high-pressure oil filter nozzle is assembled and thread force analysis when the high-pressure oil filter nozzle is supplied with pressure.

[0020] As a further improvement of the present invention, the force analysis of the thread during the assembly of the high-pressure oil filter nozzle is as follows:

[0021] The tightening torque when screwing the nozzle into the oil filter cap mainly consists of two parts. One part is the resistance torque T formed by the contact between the internal and external thread surfaces. s The other part is the friction torque T formed by the support surface of the nozzle and the contact surface of the oil filter top cover.w , respectively:

[0022]

[0023] The total tightening torque T is:

[0024]

[0025] As a further improvement of the present invention, the force analysis of the thread when the high-pressure oil filter nozzle is supplied with pressure is as follows:

[0026] When tightening the nozzle thread, the nozzle is stretched under the action of axial preload, and the contact part between the oil filter housing and the nozzle is compressed. According to the boundary condition F(x) x＝0 =F 液1 、F(x) x＝L =F 液1 +F 液2 ,

[0027]

[0028] As a further improvement of the present invention, in step 5, a mounting groove is provided on the axial outer side wall of the joint where the joint is connected to the oil filter housing, a fluoroplastic gasket is installed in the mounting groove, and a sealing ring is installed between the joint and the oil filter housing, and the inner side is fitted with the fluoroplastic gasket.

[0029] As a further improvement of the present invention, the pressure pulse test device in step 6 includes an oil tank, a manual valve connected to the oil tank, a valve, a relief valve and a solenoid valve, a cleaning filter connected to the manual valve, an electric pump connected to the cleaning filter, a one-way valve connected to the valve, the electric pump and the relief valve, and a high-temperature box connected to the solenoid valve and the one-way valve, a radiator is arranged between the solenoid valve and the oil tank, a pressure gauge and an accumulator are arranged between the high-temperature box and the one-way valve, and a test piece is arranged in the high-temperature box.

[0030] As a further improvement of the present invention, the process of the pressure shock test performed by the pressure pulse test device in step 6 is as follows: the shock pressure rises from no more than 0.5MPa to the rated working pressure, and then drops to no more than 0.5MPa. The peak shock pressure reached by each pressure shock during the pressurization period should be 1.28 to 1.5 times the rated working pressure. The shock duration is no more than 0.6S. The high-temperature pressure shock test is performed 100,000 times on two products before and after the improvement at a rate of 60 to 100 times / min. When the test oil temperature is 90 to 125°C, the shock is performed 75,000 times, and when the test oil temperature is 125 to 150°C, the shock is performed 25,000 times.

[0031] As a further improvement of the present invention, the appearance of the matching nozzle of the product in step 6 is required to be free of oil leakage or oil seepage.

[0032] As a further improvement of the present invention, the disassembly and inspection of the matching take-over nozzle of the product in step 6 requires that the sealing ring is intact and has no bite phenomenon.

[0033] The beneficial effects of the present invention are:

[0034] The present invention solves the problem of oil leakage caused by the long-term extrusion and biting of the sealing ring gap in the high-pressure oil filter nozzle through a method for improving the high-pressure oil filter sealing structure based on finite element simulation analysis, and meets the demand for reliable use of the product during its life cycle. During the product repair process, fluoroplastic gaskets of different thicknesses are selected to fill the gap between the housing and the nozzle installation, thereby ensuring the repair quality and reliability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0036] Figure 1 This is a schematic diagram of the force on the threaded connection of the take-over nozzle during assembly;

[0037] Figure 2 This is the deformation diagram of the thread connection of the take-off nozzle;

[0038] Figure 3 It is the thread simulation assembly drawing;

[0039] Figure 4 It is a simulation model of the sealing ring;

[0040] Figure 5 This is the equivalent stress cloud diagram of the sealing ring after assembly;

[0041] Figure 6 This is the equivalent stress cloud diagram of the sealing ring after pressurization;

[0042] Figure 7 This is the equivalent stress cloud diagram of the sealing ring after pressure relief;

[0043] Figure 8 For the improved installation simulation model;

[0044] Fig. 9 Schematic diagram of the pressure pulse test device.

[0045] In the figure: 1. Oil tank; 2. Manual valve; 3. Cleaning filter; 4. Valve; 5. Electric pump; 6. Overflow valve; 7. Check valve; 8. Pressure gauge; 9. Accumulator; 10. Solenoid valve; 11. Radiator; 12. Test piece; 13. High temperature box. DETAILED DESCRIPTION

[0046] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below with reference to the accompanying drawings and embodiments.

[0047] A method for improving a high-pressure oil filter sealing structure based on finite element simulation analysis comprises the following steps:

[0048] Step 1: Failure analysis of damage to the sealing ring of the high-pressure oil filter nozzle: Perform failure analysis on the damage to the sealing ring of the nozzle to preliminarily determine the cause of the seal failure.

[0049] Specifically, for the failure of the sealing ring of the threaded connection of the high-pressure oil filter nozzle due to damage, macro-inspection, micro-observation, hardness analysis, gap measurement and other methods will be used, combined with the common failure characteristics of O-rings and the stress analysis of the nozzle sealing ring. It is determined that the cause of the sealing ring damage is the extrusion damage caused by the 0.09mm end face gap between the nozzle and the oil filter housing after installation.

[0050] Step 2: Force analysis of high-pressure oil filter nozzle threads: Use the Yamamoto function method to study the force load distribution of the threads during assembly and pressure supply of the high-pressure oil filter nozzle, calculate the change in the gap between the nozzle and the housing installation end face, and derive the relationship between the nozzle tightening torque and preload.

[0051] Specifically, it includes the force analysis of the threads when the high-pressure oil filter nozzle is assembled and the force analysis of the threads when the high-pressure oil filter nozzle is supplied with pressure.

[0052] Among them, the force analysis of the thread during the assembly of the high-pressure oil filter nozzle is as follows:

[0053] The tightening torque when screwing the nozzle into the oil filter cap mainly consists of two parts. One part is the resistance torque T formed by the contact between the internal and external thread surfaces. s The other part is the friction torque T formed by the support surface of the nozzle and the contact surface of the oil filter top cover. w , respectively:

[0054]

[0055] The total tightening torque T is:

[0056]

[0057] like Figure 1 The figure shows the schematic diagram of the threaded connection of the nozzle. The nozzle is subjected to a tensile force F. Taking the top surface position of the nozzle nut as the origin O, the axial force acting on the vertical section of the nozzle at the x position is F. x .

[0058] The force analysis of the thread when the high-pressure oil filter nozzle is supplied with pressure is as follows:

[0059] When tightening the nozzle thread, the nozzle is stretched under the action of axial preload, and the contact part between the oil filter housing and the nozzle is compressed. The deformation relationship is as follows: Figure 2 shown.

[0060] According to the boundary condition F(x) x＝0 =F 液1 、F(x) x＝L =F 液1 +F 液2 ,

[0061]

[0062] Step 3: Finite element simulation of the threaded connection between the pipe nozzle and the shell: parametric modeling of the threaded connection structure between the pipe nozzle and the shell is performed, and finite element analysis of the pipe nozzle thread during pressure supply is carried out to verify the consistency between the end face clearance value obtained by the simulation analysis and the value calculated by the function theory.

[0063] Specifically, the threaded parts of the nozzle and the oil filter housing are modeled using a parametric modeling method, and then the threaded parts are bound to the corresponding nozzle and the oil filter housing to form an assembly. The original model is simplified, and the assembly relationship and interaction settings after simplification are as follows: Figure 3 As shown, the structure is meshed, with C3D8 units used for the threaded part and C3D8R units used for the rest.

[0064] Step 4: Finite element simulation of high-pressure oil filter seal damage and establishment of simulation model: In view of the fact that the O-ring is an axisymmetric structure, an axisymmetric two-dimensional model is used to analyze the seal. The nozzle and the oil filter housing are simplified, and the structure of the contact part with the seal is retained. The components are meshed and a mesh simulation model of the seal is established. Simulation analysis is carried out on the equivalent stress and appearance deformation of the seal in three states: after assembly, when supplying pressure, and after pressure relief.

[0065] Since the oil filter housing and the nozzle are relatively rigid compared to the sealing ring, they are set as rigid bodies and the meshes of the components are divided. The assembly structure after the nozzle is installed on the housing and the mesh model of the sealing ring are as follows: Figure 4 As shown. After simulation calculation, Figure 5 As shown in the figure, after assembly, the maximum equivalent stress of the sealing ring is 25.83Mpa; Figure 6 As shown in the figure, after applying a pressure of 28MPa, the maximum equivalent stress of the sealing ring is 36.31MPa, but the sealing ring is obviously squeezed out to the fillet after pressurization; Figure 7 As shown in the figure, after pressure relief, the maximum equivalent stress of the sealing ring is 26.15MPa.

[0066] Step 5, research the improvement method of the nozzle structure: Based on the above force analysis, in order to change the end face gap between the nozzle and the upper shell and reduce the possibility of the seal ring being squeezed in, according to the aircraft hydraulic system design margin standard, when the actual product end face gap can reach a maximum of 0.1mm, it is necessary to improve it by at least 1.5 times the maximum gap and fill it by adding fluoroplastic gaskets. Figure 8 As shown, specifically, a mounting groove is provided on the axial outer side wall of the joint where the joint is connected to the oil filter housing, a fluoroplastic gasket is installed in the mounting groove, and a sealing ring is installed between the joint and the oil filter housing, and the inner side is fitted with the fluoroplastic gasket.

[0067] Step 6: Build test verification for improvement of nozzle sealing structure:

[0068] A pressure pulse test device is designed, and a pressure shock test is used to detect the pressure resistance and shock resistance of the test piece 12. This step is repeated to simulate the product in an extreme working environment to verify the product reliability. After the pressure shock test, a low-pressure sealing test and a high-pressure sealing test are performed, and the appearance of the product's matching take-over nozzle is checked and the product's matching take-over nozzle is disassembled for inspection.

[0069] Specifically, Fig. 9 As shown, the pressure pulse test device includes an oil tank 1, a manual valve 2 connected to the oil tank 1, a valve 4, a relief valve 6 and a solenoid valve 10, a cleaning filter 3 connected to the manual valve 2, an electric pump 5 connected to the cleaning filter 3, a one-way valve 7 connected to the valve 4, the electric pump 5 and the relief valve 6, and a high-temperature box 13 connected to the solenoid valve 10 and the one-way valve 7. A radiator 11 is arranged between the solenoid valve 10 and the oil tank 1, a pressure gauge 8 and an accumulator 9 are arranged between the high-temperature box 13 and the one-way valve 7, and a test piece 12 is arranged in the high-temperature box 13.

[0070] The oil tank 1 is used to store the oil required to ensure the operation of the hydraulic system; the manual valve 2 is used as a control component in the pipeline fluid delivery system to change the passage section and the flow direction of the medium; the cleaning filter 3 is used to filter the polluted particles in the oil in the circulation pipeline; the electric pump 5 is used to provide power for the product, and realizes the pressure shock and pressure relief functions through the overflow valve 6, the solenoid valve 10 and other components; the overflow valve 6 plays a role in constant pressure overflow and pressure stabilization, system unloading and safety protection; the one-way valve 7 is used to prevent the reverse flow of oil in the hydraulic system; the accumulator 9 is used to maintain the system pressure stability; the solenoid valve 10 is used to control the hydraulic flow direction; the radiator 11 is used for heat dissipation of the hydraulic system to accelerate the heat dissipation speed; the high temperature box 13 is used to provide the high temperature environment required for the test.

[0071] Pressure shock test The process of pressure shock test is as follows: the shock pressure rises from no more than 0.5MPa to the rated working pressure, and then drops to no more than 0.5MPa. The peak shock pressure reached during each pressure shock during the pressurization period should be 1.28 to 1.5 times the rated working pressure, and the shock duration should not exceed 0.6S. The high-temperature pressure shock test is carried out 100,000 times at a rate of 60 to 100 times / min on two products before and after the improvement. When the test oil temperature is 90 to 125℃, the shock is 75,000 times, and when the test oil temperature is 125 to 150℃, the shock is 25,000 times. After the test, the low-pressure sealing test and high-pressure sealing test are carried out again. Check that the appearance of the matching nozzle of the product should be normal, and there should be no oil leakage or oil seepage. The matching nozzle of the product is disassembled and inspected, and the sealing ring should be intact and there should be no bite.

[0072] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis, characterized in that: The following steps are involved: Step 1: Failure analysis of the high-pressure oil filter nozzle seal ring damage: Conduct failure analysis on the damage of the nozzle seal ring and preliminarily determine the cause of the seal failure; Step 2: Force analysis of high pressure oil filter nozzle thread: The Yamamoto function method is used to study the load distribution of the thread during the assembly and pressure supply of the high-pressure oil filter nozzle, calculate the change of the gap between the nozzle and the shell installation end face, and obtain the relationship between the nozzle tightening torque and preload. Step 3: Finite element simulation of the threaded connection between the butt nozzle and the shell: The threaded connection structure between the nozzle and the shell was parametrically modeled, and the finite element analysis of the nozzle thread during pressure supply was carried out to verify the consistency between the end face clearance value obtained by simulation analysis and the value calculated by function theory; Step 4: Finite element simulation of high-pressure oil filter seal damage and establishment of simulation model: In view of the fact that the O-ring is an axisymmetric structure, an axisymmetric two-dimensional model is used to analyze the sealing ring. The nozzle and the oil filter housing are simplified, and the structure of the contact part with the sealing ring is retained. The various components are meshed, and a mesh simulation model of the sealing ring is established. The equivalent stress and appearance deformation of the sealing ring in three states, after assembly, when supplying pressure, and after pressure relief, are simulated and analyzed. Step 5: Study the method of improving the nozzle structure: Based on the above force analysis, in order to change the end face clearance between the nozzle and the upper shell and reduce the possibility of the seal ring being squeezed in, according to the aircraft hydraulic system design margin standard, when the actual product end face clearance can reach a maximum of 0.1mm, it is necessary to improve it by at least 1.5 times the maximum clearance and fill it by adding a fluoroplastic gasket; Step 6: Build test verification for improvement of nozzle sealing structure: A pressure pulse test device is designed, and a pressure shock test is used to detect the pressure resistance and shock resistance of the test piece (12). This step is repeated to simulate the product in an extreme working environment to verify the product reliability. After the pressure shock test, a low-pressure sealing test and a high-pressure sealing test are performed to check the appearance of the product's matching nozzle and to disassemble and inspect the product's matching nozzle.

2. The method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis according to claim 1 is characterized in that: The failure analysis of the damage to the nozzle seal in step 1 includes: macro inspection, micro observation, hardness analysis, gap measurement, combined with the common failure form characteristics of O-rings and the stress analysis of the nozzle seal.

3. The method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis according to claim 1 is characterized in that: Step 2 includes thread force analysis when the high-pressure oil filter nozzle is assembled and thread force analysis when the high-pressure oil filter nozzle is supplied with pressure.

4. The method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis according to claim 3 is characterized in that: The force analysis of the thread during the assembly of the high-pressure oil filter nozzle is as follows: The tightening torque when screwing the nozzle into the oil filter cap mainly consists of two parts. One part is the resistance torque T formed by the contact between the internal and external thread surfaces. s The other part is the friction torque T formed by the support surface of the nozzle and the contact surface of the oil filter top cover. w , respectively: The total tightening torque T is:

5. The method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis according to claim 3 is characterized in that: The force analysis of the thread when the high-pressure oil filter nozzle is supplied with pressure is as follows: When tightening the nozzle thread, the nozzle is stretched under the action of axial preload, and the contact part between the oil filter housing and the nozzle is compressed. According to the boundary condition F(x) x＝0 =F 液1 、F(x) x＝L =F 液1 +F 液2 , 6. The method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis according to claim 1 is characterized in that: In step 5, a mounting groove is provided on the axial outer side wall of the joint where the joint is connected to the oil filter housing, a fluoroplastic gasket is installed in the mounting groove, and a sealing ring is installed between the joint and the oil filter housing, with the inner side fitting the fluoroplastic gasket.

7. The method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis according to claim 1 is characterized in that: The pressure pulse test device in step 6 comprises an oil tank (1), a manual valve (2) connected to the oil tank (1), a valve (4), a relief valve (6) and a solenoid valve (10), a cleaning filter (3) connected to the manual valve (2), an electric pump (5) connected to the cleaning filter (3), a one-way valve (7) connected to the valve (4), the electric pump (5) and the relief valve (6), and a high-temperature box (13) connected to the solenoid valve (10) and the one-way valve (7); a radiator (11) is arranged between the solenoid valve (10) and the oil tank (1); a pressure gauge (8) and a pressure accumulator (9) are arranged between the high-temperature box (13) and the one-way valve (7); and a test piece (12) is arranged in the high-temperature box (13).

8. The method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis according to claim 1 is characterized in that: The process of the pressure shock test performed by the pressure pulse test device in step 6 is as follows: the shock pressure rises from no more than 0.5MPa to the rated working pressure, and then drops to no more than 0.5MPa. The peak shock pressure reached by each pressure shock during the pressurization period should be 1.28 to 1.5 times the rated working pressure. The shock duration is no more than 0.6S. The high-temperature pressure shock test is performed 100,000 times on two products before and after the improvement at a rate of 60 to 100 times / min. When the test oil temperature is 90 to 125°C, the shock is performed 75,000 times, and when the test oil temperature is 125 to 150°C, the shock is performed 25,000 times.

9. The method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis according to claim 1, characterized in that: In step 6, the appearance of the product's matching nozzle must not show any oil leakage or seepage.

10. The method for improving the sealing structure of a high-pressure oil filter based on finite element simulation analysis according to claim 1, characterized in that: In step 6, disassemble and inspect the matching nozzle of the product and ensure that the sealing ring is intact without any bite damage.

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