Pressure accumulator sealing performance test system and test method for simulating piston offset

Abstract

The invention discloses a pressure accumulator sealing performance test system and test method for simulating piston offset. The test system comprises a hydraulic control unit, an air-tight seal detection tool, and a left lifting unit, a simulation pressure accumulator unit and a right lifting unit which are sequentially arranged from left to right, the hydraulic control unit and the air seal detection tool are connected with a liquid cavity and an air cavity in the simulation pressure accumulator unit respectively, and the left end and the right end of a piston rod in the simulation pressure accumulator unit extend outwards respectively and are connected with the left lifting unit and the right lifting unit respectively. A left displacement sensor and a right displacement sensor are arranged on one side of the left lifting unit and one side of the right lifting unit respectively. According to the invention, stepless adjustment of different offsets and deflection angles of the piston and comparative analysis of sealing performance are realized, so that a test platform is provided for design and optimization of a pressure accumulator prototype, and the device has good practicability.

Description

Technical Field

[0001] The invention belongs to the technical field of sealing performance testing of a pressure accumulator under piston displacement, and in particular relates to a pressure accumulator sealing performance testing system and a testing method for simulating piston displacement. Background Art

[0002] In the petrochemical, aviation and other industries, accumulators are widely used as emergency auxiliary oil sources for hydraulic systems and to absorb pressure pulses. However, with the emergence of higher pressure, higher speed and extremely low temperature extreme operating conditions, there are more and more cases of leakage of the piston movable seal that achieves oil and gas isolation inside the accumulator. According to analysis, the piston offset deflection caused by the friction of the piston seal, the piston hitting the bottom and its own gravity is one of the main causes of leakage.

[0003] At present, no research has been found that uses a test bench to analyze in detail the impact of offset on the sealing performance of seals. At the same time, the accumulator piston offset is used as an internal seal, and it is difficult to observe the state of the piston and its seals. There is no sealing performance test system that simulates the accumulator piston offset. Secondly, the sealing performance test system must meet the following requirements:

[0004] 1. Able to steplessly adjust different piston offsets and deflection angles;

[0005] 2. It must be versatile and able to detect the internal and external sealing performance of the accumulator, and be able to detect the performance and life of rubber seals of different sizes and compression ratios;

[0006] 3. It can quantitatively analyze different piston deflections and the sealing performance of the seal under different piston deflections;

[0007] 4. It should be able to simulate the full working conditions of the accumulator and collect and feedback the test data. The test process should be safe and reliable. Summary of the invention

[0008] The object of the present invention is to provide a pressure accumulator sealing performance testing system and testing method for simulating piston displacement, which are used to simulate the displacement deflection state of the pressure accumulator piston and perform gas sealing performance testing.

[0009] The present invention is mainly achieved through the following technical solutions:

[0010] A pressure accumulator sealing performance test system simulating piston displacement comprises a hydraulic control unit, an air-tightness detection tool, and a left lifting unit, a simulated pressure accumulator unit and a right lifting unit arranged in sequence from left to right; the hydraulic control unit and the air-tightness detection tool are respectively connected to a liquid cavity and an air cavity inside the simulated pressure accumulator unit, the left and right ends of a piston rod inside the simulated pressure accumulator unit are respectively extended with external devices and are respectively connected to a left lifting unit and a right lifting unit, and a left displacement sensor and a right displacement sensor are respectively arranged on one side of the left lifting unit and the right lifting unit.

[0011] In order to better realize the present invention, further, the hydraulic control unit includes an oil tank, an electric plunger pump, a first one-way valve, a second one-way valve, an overflow valve, a two-position two-way solenoid reversing valve, a two-position three-way solenoid reversing valve and a manual stop valve; the oil tank is connected to the second one-way valve, the first one-way valve is connected to the two-position two-way solenoid reversing valve, and the overflow valve and the two-position three-way solenoid reversing valve are connected to the liquid chamber inside the simulated accumulator unit through the manual stop valve; the first one-way valve and the second one-way valve are in opposite directions, which are used to prevent the reverse flow of oil from causing the electric plunger pump to reverse.

[0012] In order to better realize the present invention, further, the hydraulic control unit also includes a first pressure sensor and a second pressure sensor, the first pressure sensor is respectively connected to the second one-way valve and the overflow valve, and is used to detect the system inlet pressure; the second pressure sensor is connected to the output end of the manual stop valve, and is used to detect the pressure of the liquid chamber inside the simulated accumulator unit.

[0013] In order to better implement the present invention, further, a cooler is arranged inside the oil tank, and an oil level sensor and a first temperature sensor are also arranged on the oil tank.

[0014] In order to better realize the present invention, further, the left adjusting unit includes a left base, a left locking nut, a left adjusting nut and a left rising base; the top of the left base is provided with a smooth rod and a threaded rod connected in sequence from top to bottom, the diameter of the smooth rod is smaller than the diameter of the threaded rod, the outer sliding sleeve of the smooth rod is provided with a left rising base, the outer side of the threaded rod is threadedly connected with a left adjusting nut and a left locking nut in sequence from top to bottom, the left adjusting nut is abutted against the left rising base, and the top of the rising base is connected to the piston rod; the left displacement sensor is installed on the left base, for measuring the displacement change of the left rising base; the left lifting unit and the right lifting unit have the same structure.

[0015] In order to better realize the present invention, further, the simulated accumulator unit includes a floating end cover, a fixed end cover, an outer cylinder, a piston and a piston rod; the left and right ends of the outer cylinder are respectively provided with fixed end covers, and the outer side of the fixed end cover is slidably provided with a floating end cover; a piston rod is provided inside the outer cylinder, and the left and right ends of the piston rod respectively extend through the fixed end cover and the floating end cover, and a through hole is provided in the middle part of the fixed end cover corresponding to the piston rod, and the diameter of the through hole is larger than the diameter of the piston rod; a piston is provided in the middle part of the piston rod, and the piston divides the inside of the outer cylinder into a liquid chamber and an air chamber, and the piston and the outer cylinder, as well as the piston rod and the floating end cover are dynamically sealed and connected respectively.

[0016] In order to better implement the present invention, further, the floating end cover is connected to the fixed end cover by bolts, and the floating end cover is provided with a light avoidance hole corresponding to the bolt, and the diameter of the light avoidance hole is larger than the diameter of the bolt, so that the floating end cover can slide relative to the fixed end cover.

[0017] In order to better realize the present invention, further, the airtight detection tooling, left lifting unit, right lifting unit and simulated accumulator unit are respectively arranged inside the low-temperature environment box; the low-temperature environment box is connected to a second temperature sensor, and the second temperature sensor is used to detect the temperature inside the low-temperature environment box.

[0018] In order to better implement the present invention, further, a plurality of sealing plugs are arranged on the peripheral side of the air-tightness detection tooling, and a third temperature sensor and a third pressure sensor are arranged between the air-tightness detection tooling and the simulated accumulator unit.

[0019] The present invention is mainly achieved through the following technical solutions:

[0020] A method for testing the sealing performance of a pressure accumulator under simulated piston displacement is performed using the above-mentioned sealing performance simulation test system under pressure accumulator piston displacement, and comprises the following steps:

[0021] S1: Assemble the test system;

[0022] S2: Adjust the test temperature of the test system to simulate the ambient temperature;

[0023] S3: fixed seal boundary test;

[0024] S31: adjust the overflow valve pressure to simulate the rated working pressure of the accumulator, and start the electric plunger pump and the two-position three-way electromagnetic reversing valve;

[0025] S32: Close the manual stop valve to hold the pressure in the simulated accumulator, immerse the air seal detection tooling in the oil, and observe the bubbles in the sealing plug;

[0026] S4: Piston offset and deflection adjustment;

[0027] S41: In the initial stage, the displacement detection values ​​of the left displacement sensor and the right displacement sensor are both zero, and the left lifting unit and the right lifting unit are adjusted respectively to make the displacement change values ​​of the left displacement sensor and the right displacement sensor consistent, so that the piston is offset, and the piston offset sealing boundary test is carried out;

[0028] S42: adjusting the left lifting unit and the right lifting unit so that the displacement change values ​​of the left displacement sensor and the right displacement sensor are inconsistent, so that the piston inside the simulated accumulator unit is deflected, and a piston deflection sealing boundary test is performed;

[0029] S5: Sealing boundary test under piston offset and deflection;

[0030] S51: adjust the overflow valve pressure to simulate the rated working pressure of the accumulator, start the electric plunger pump, the two-position three-way electromagnetic reversing valve and the manual stop valve;

[0031] S52: recording the pressure of the liquid chamber and the gas chamber of the simulated accumulator unit, setting a cycle test, and collecting the number of times the two-position three-way electromagnetic reversing valve is energized based on the counter, which is the number of working cycles of the simulated accumulator;

[0032] S53: After the test is completed, the pressure data of the liquid chamber and the air chamber are compared and analyzed to obtain the sealing conditions of the piston at different offset deflections.

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

[0034] The present invention realizes stepless adjustment of different piston offsets and deflection angles through the left lifting unit and the right lifting unit, and realizes comparative analysis of the sealing performance of rubber parts with different compression rates through the hydraulic control unit and the air sealing detection tooling, thereby providing a test platform for accumulator prototype design and optimization, ensuring the feasibility of new products, and effectively improving the sealing performance of the accumulator.

[0035] The present invention realizes stepless adjustment of different piston offsets and deflection angles by means of the structures of the locking nut, the adjusting nut, the lifting base and the floating end cover, and the operation is simple and reliable. The displacement sensor provided in the present invention can follow the adjusting nut, calculate the piston offset deflection, and quantitatively analyze the sealing performance of the seal under different piston offset deflections. The present invention can realize the detection of rubber seals with different compression rates by providing sealing grooves of different sizes on the sealing plug and cooperating with rubber rings. The sensor and data acquisition device provided in the present invention realize real-time monitoring of the test process, and the test data during the test process can be recorded. The safety valve provided can ensure the safety and reliability of the system, and has good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1It is a structural schematic diagram of a sealing performance simulation test system of a pressure accumulator under piston displacement of the present invention;

[0037] Figure 2 This is the principle block diagram of the hydraulic control unit;

[0038] Figure 3 It is a structural schematic diagram of the left lifting unit;

[0039] Figure 4 It is a structural schematic diagram of the right lifting unit;

[0040] Figure 5 It is a structural schematic diagram of the simulated accumulator unit;

[0041] Figure 6 The flowchart of the sealing performance simulation test method of the accumulator piston under deviation of the present invention.

[0042] Among them: 100-hydraulic control unit, 101-oil tank, 102-oil level sensor, 103-first temperature sensor, 104-cooler, 105-filter, 106-electric plunger pump, 107-first check valve, 108-second check valve, 109-first pressure sensor, 110-overflow valve, 111-two-position two-way electromagnetic reversing valve, 112-counter, 113-two-position three-way electromagnetic reversing valve, 114-manual stop valve, 115-second pressure sensor, 116-second temperature sensor, 117-calculator, 118-PLC, 119-data collector,

[0043] 200-left lifting unit, 201-left base, 202-left locking nut, 203-left adjusting nut, 204-left rising base, 205-left displacement sensor,

[0044] 300-right lifting unit, 301-right base, 302-right locking nut, 303-right adjusting nut, 304-right rising base, 305-right displacement sensor,

[0045] 400-simulated accumulator unit, 401-low temperature environment chamber, 403-floating end cover, 404-fixed end cover, 405-liquid chamber, 406-outer cylinder, 4081-piston, 409-air chamber, 4082-piston rod, 410-vent, 411-third temperature sensor, 412-third pressure sensor, 413-gas seal detection tooling, 414-sealing plug, 415-accumulator base, 417-end cover fixed seal, 418-steel ball ring, 419-liquid port, 420-end face seal, 422-test bench. DETAILED DESCRIPTION

[0046] Embodiment 1:

[0047] A pressure accumulator sealing performance test system simulating piston displacement includes: a hydraulic control unit 100, a test bench 422 arranged inside a low temperature environment box 401, a gas seal detection tool 413, a left lifting unit 200, a right lifting unit 300 and a simulated pressure accumulator unit 400, wherein the left lifting unit 200, the simulated pressure accumulator unit 400 and the right lifting unit 300 are sequentially installed on the test bench 422. A second temperature sensor 116 is installed on the low temperature environment box 401, and the second temperature sensor 116 is used to detect the temperature of the low temperature environment box 401, and the low temperature environment box 401 is used to adjust the test temperature to achieve the temperature working condition simulation of the pressure accumulator.

[0048] Preferably, a plurality of sealing plugs 414 are provided around the airtightness detection tool 413. The airtightness detection tool 413 is immersed in oil to determine the sealing leakage point according to the bubble situation. The sealing plug 414 is a plug equipped with sealing elements with different compression rates, which can test the compression rate and pressure leakage limit of the sealing element.

[0049] Preferably, if Figure 1 and Figure 2 As shown, the hydraulic control unit 100 includes an oil tank 101, a cooler 104, a filter 105, an electric piston pump 106, a first one-way valve 107, a second one-way valve 108, a relief valve 110, a two-position two-way electromagnetic reversing valve 111, a two-position three-way electromagnetic reversing valve 113, and a manual stop valve 114.

[0050] The oil tank 101 is connected to the electric plunger pump 106 through the filter 105, and the electric plunger pump 106 is connected to the two-position three-way electromagnetic reversing valve 113 through the second one-way valve 108; the oil tank 101 is connected to the two-position three-way electromagnetic reversing valve 113 through the overflow valve 110; the oil tank 101 is connected to the two-position two-way electromagnetic reversing valve 111 through the first one-way valve 107, and the two-position two-way electromagnetic reversing valve 111 is connected to the two-position three-way electromagnetic reversing valve 113. The two-position three-way electromagnetic reversing valve 113 is connected to the liquid port 419 of the simulated accumulator unit 400 through the manual stop valve 114.

[0051] The first one-way valve 107 and the second one-way valve 108 can limit the direction of the oil to prevent the reverse direction of the oil from causing the electric plunger pump 106 to reverse.

[0052] Specifically, the output ends of the second one-way valve 108 and the overflow valve 110 are provided with a first pressure sensor 109, the output end of the manual stop valve 114 is provided with a second pressure sensor 115, and the oil tank 101 is provided with a cooler 104 inside, and is equipped with an oil level sensor 102 and a first temperature sensor 103. The cooler 104 is used to adjust the oil temperature of the oil tank 101. The oil level sensor 102 is used to detect the oil condition of the oil tank 101, the first temperature sensor 103 is used to detect the oil temperature of the oil tank 101, the first pressure sensor 109 is used to detect the system inlet pressure, and the second pressure sensor 115 is used to detect the pressure of the accumulator liquid chamber 405.

[0053] The two-position two-way electromagnetic reversing valve 111 is used as a safety valve. When the pressure value collected by the first pressure sensor 109 or the second pressure sensor 115 exceeds the standard, the oil returns directly to the oil tank 101 through the two-position two-way electromagnetic reversing valve 111. The overflow valve 110 is used to adjust the system pressure. The two-position three-way electromagnetic reversing valve 113 is used to change the direction of the oil in the liquid chamber 405.

[0054] It also includes a PLC 118, a calculator 117 and a data collector 119 connected in sequence, and the data collector 119 is connected to each temperature sensor, pressure sensor and each valve. The data collector 119 is connected to the two-position three-way electromagnetic reversing valve 113 through a counter 112, and the counter 112 is used for sealing life detection. The pressure, temperature and reversal times collected by each sensor are transmitted to the computer through the data collector 119, and the computer controls the electromagnetic valve group and the electric plunger pump 106 through the PLC 118 to realize closed-loop control.

[0055] Preferably, if Figure 3 As shown, the left lifting unit 200 includes a left base 201, a left locking nut 202, a left adjusting nut 203, a left rising base 204 and a left displacement sensor 205. Figure 4 As shown, the right lifting unit 300 includes a right base 301 , a right locking nut 302 , a right adjusting nut 303 , a right rising base 304 and a right displacement sensor 305 .

[0056] The left base 201 and the right base 301 are connected to the test bench 422 by bolts. The lower end of the connecting rod in the middle of the left base 201 and the right base 301 is a threaded rod, and the upper end is a smooth rod, and the diameter of the smooth rod is smaller than the diameter of the threaded rod. The inner holes of the left rising base 204 and the right rising base 304 are respectively matched with the smooth rods on the left base 201 and the right base 301. By adjusting the positions of the left adjusting nut 203 and the right adjusting nut 303, the left locking nut 202 and the right locking nut 302 are locked, so that the upper and lower positions of the left rising base 204 and the right rising base 304 can be adjusted.

[0057] The left displacement sensor 205 is connected to the left rising base 204 to measure the displacement change of the left rising base 204 , and the right displacement sensor 305 is connected to the right rising base 304 to measure the displacement change of the right rising base 304 .

[0058] Preferably, if Figure 5 As shown, the simulated accumulator unit 400 includes bolts, a floating end cover 403, a fixed end cover 404, a liquid chamber 405, an outer cylinder 406, a piston 4081, an air chamber 409, a piston rod 4082, a vent 410, an accumulator base 415, a liquid port 419, and an end face seal 420.

[0059] The outer cylinder 406 is connected to the test bench 422 through the accumulator base 415. A piston rod 4082 is provided inside the outer cylinder 406, and a piston 4081 is provided in the middle of the piston rod 4082. The piston 4081 and the outer cylinder 406 are movably sealed. The piston 4081 divides the inside of the outer cylinder 406 into a liquid chamber 405 and an air chamber 409. The left and right ends of the piston rod 4082 extend out of the outer cylinder 406 and are respectively connected to the left rising base 204 and the right rising base 304. The displacement changes of the left rising base 204 and the right rising base 304 can be converted into the displacement changes of the piston 4081, and then the offset deflection of the piston 4081 can be analyzed.

[0060] The floating end cover 403 is connected to the fixed end cover 404 by bolts. The bolt holes of the floating end cover 403 are smooth holes with a gap between the bolts. There is a gap between the inner hole of the fixed end cover 404 and the piston rod 4082 to prevent the floating end cover 403 and the fixed end cover 404 from interfering with the piston rod 4082 when the piston rod 4082 drives the piston 4081 to deviate and adjust. The piston rod 4082 and the floating end cover 403 are movably sealed.

[0061] The floating end caps 403 and the fixed end caps 404 on the left and right sides are provided with liquid through holes 419 and air vents 410 corresponding to the liquid cavity 405 and the air cavity 409 respectively. An end cap fixing seal 417 is provided between the floating end cap 403 and the fixed end cap 404 .

[0062] A third temperature sensor 411 and a third pressure sensor 412 are provided between the air-tightness detection tool 413 and the simulated accumulator unit 400. The third temperature sensor 411 is used to detect the temperature of the air cavity 409, and the third pressure sensor 412 is used to detect the pressure of the air cavity 409.

[0063] An end cover fixing seal 417 and a steel ball ring 418 are provided between the outer cylinder 406 and the fixed end cover 404. The steel ball ring 418 is used to realize the axial connection between the fixed end cover 404 and the outer cylinder 406, making the structure more compact.

[0064] Embodiment 2:

[0065] A method for testing the sealing performance of a pressure accumulator by simulating piston displacement is performed using the above-mentioned sealing performance simulation test system under the displacement of the pressure accumulator piston 4081, and includes the following steps:

[0066] S1: Test preparation and installation process:

[0067] S11: Connect and assemble the air-tightness detection tool 413 and the simulated pressure accumulator, and fill the air cavity 409 with nitrogen of a certain pressure through the charging valve;

[0068] S12: The left lifting unit 200, the right lifting unit 300, and the simulated accumulator unit 400 are fixed on the test bench 422 by bolts;

[0069] S13: Figure 1 As shown, connect the units together, adjust the system pressure to a lower pressure, turn on the electric piston pump 106, and check the sealing condition of the hydraulic pipeline interface and the numerical detection condition of each sensor.

[0070] S2: Ambient temperature simulation process:

[0071] S21: Start the cooler 104 and the low temperature environment box 401, and start the test when the data fed back by the first temperature sensor 103 and the second temperature sensor 116 are the temperature setting values.

[0072] S3: Fixed sealing boundary test process:

[0073] S31: The pressure of the overflow valve 110 is adjusted to the rated working pressure of the simulated accumulator, and the electric plunger pump 106 and the two-position three-way electromagnetic reversing valve 113 are turned on.

[0074] S32: Close the manual stop valve 114 to hold the pressure in the simulated accumulator, immerse the air-tightness detection tool 413 in the oil, and observe the air bubbles in the sealing plug 414.

[0075] S4: Piston 4081 offset and deflection adjustment process:

[0076] S41: In the initial stage, the displacement detection values ​​of the left displacement sensor 205 and the right displacement sensor 305 are both zero, and the left adjusting nut 203 and the right adjusting nut 303 are adjusted respectively, and the floating end cover 403 is adjusted. At the same time, the displacement change values ​​of the left displacement sensor 205 and the right displacement sensor 305 are made consistent, so that the piston 4081 is offset, and the piston 4081 offset sealing boundary test is carried out;

[0077] S42: Adjust the left adjusting nut 203 and the right adjusting nut 303, and adjust the floating end cover 403, so that the displacement change values ​​of the left displacement sensor 205 and the right displacement sensor 305 are inconsistent, so that the piston 4081 is deflected, and a piston 4081 deflection sealing boundary test is carried out.

[0078] S5: Piston 4081 offset and deflection seal boundary test process, specifically including the following steps:

[0079] S51: adjust the pressure of the relief valve 110 to the rated working pressure of the simulated accumulator, and start the electric plunger pump 106, the two-position three-way electromagnetic reversing valve 113 and the manual stop valve 114;

[0080] S52: Record the values ​​of the second pressure sensor 115 and the third pressure sensor 412, set a cycle test, the number of times collected by the counter 112 is the number of times the two-position three-way electromagnetic reversing valve 113 is energized, that is, the number of simulated accumulator working cycles;

[0081] S53: After the test is completed, the data of the pressure sensor are compared and analyzed to obtain the sealing conditions of the piston 4081 at different offset deflections.

[0082] S6: Close the valve and power supply, disconnect the simulated accumulator hydraulic pipeline, and organize the pipelines and data.

[0083] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A pressure accumulator sealing performance test system simulating piston displacement, characterized in that: The invention comprises a hydraulic control unit (100), an air-tightness detection tool (413), and a left lifting unit (200), a simulated accumulator unit (400), and a right lifting unit (300) which are arranged in sequence from left to right; the hydraulic control unit (100) and the air-tightness detection tool (413) are respectively connected to a liquid cavity (405) and an air cavity (409) inside the simulated accumulator unit (400); the left and right ends of a piston rod (4082) inside the simulated accumulator unit (400) are respectively extended to external devices and respectively connected to the left lifting unit (200) and the right lifting unit (300); a left displacement sensor (205) and a right displacement sensor (305) are respectively arranged on one side of the left lifting unit (200) and the right lifting unit (300).

2. The accumulator sealing performance testing system simulating piston displacement according to claim 1, characterized in that: The hydraulic control unit (100) comprises an oil tank (101), an electric piston pump (106), a first one-way valve (107), a second one-way valve (108), a relief valve (110), a two-position two-way electromagnetic reversing valve (111), a two-position three-way electromagnetic reversing valve (113) and a manual stop valve (114); the oil tank (101) is connected to the second one-way valve (108), the first one-way valve (107) and the second one-way valve (108) respectively through the electric piston pump (106). ) is connected to a two-position two-way electromagnetic reversing valve (111), a relief valve (110) and a two-position three-way electromagnetic reversing valve (113); the two-position three-way electromagnetic reversing valve (113) is connected to a liquid chamber (405) inside the simulated accumulator unit (400) via a manual stop valve (114); the first one-way valve (107) and the second one-way valve (108) are in opposite directions, and are used to prevent the reverse flow of oil from causing the electric plunger pump (106) to reverse.

3. The accumulator sealing performance testing system simulating piston displacement according to claim 2, characterized in that: The hydraulic control unit (100) further comprises a first pressure sensor (109) and a second pressure sensor (115); the first pressure sensor (109) is connected to the second one-way valve (108) and the overflow valve (110) respectively, and is used to detect the system inlet pressure; the second pressure sensor (115) is connected to the output end of the manual stop valve (114), and is used to detect the pressure of the liquid chamber (405) inside the simulated accumulator unit (400).

4. The accumulator sealing performance testing system simulating piston displacement according to claim 2, characterized in that: A cooler (104) is arranged inside the oil tank (101), and an oil level sensor (102) and a first temperature sensor (103) are also arranged on the oil tank (101).

5. The accumulator sealing performance testing system simulating piston displacement according to claim 1, characterized in that: The left adjustment unit comprises a left base (201), a left locking nut (202), a left adjustment nut (203) and a left lifting base (204); a smooth rod and a threaded rod connected in sequence from top to bottom are arranged on the top of the left base (201); the diameter of the smooth rod is smaller than the diameter of the threaded rod; a left lifting base (204) is provided on the outer sliding sleeve of the smooth rod; a left adjustment nut (203) and a left locking nut (202) are threadedly connected in sequence from top to bottom on the outer side of the threaded rod; the left adjustment nut (203) abuts against the left lifting base (204), and the top of the lifting base is connected to the piston rod (4082); the left displacement sensor (205) is installed on the left base (201) and is used to measure the displacement change of the left lifting base (204); the left lifting unit (200) and the right lifting unit (300) have the same structure.

6. The accumulator sealing performance testing system simulating piston displacement according to claim 1, characterized in that: The simulated accumulator unit (400) comprises a floating end cover (403), a fixed end cover (404), an outer cylinder (406), a piston (4081) and a piston rod (4082); the fixed end covers (404) are respectively arranged at the left and right ends of the outer cylinder (406), and the floating end cover (403) is slidably arranged outside the fixed end cover (404); the piston rod (4082) is arranged inside the outer cylinder (406), and the left and right ends of the piston rod (4082) pass through the fixed end cover (404) and the floating end cover (404) respectively. The cover (403) is extended externally, and a through hole is provided in the middle of the fixed end cover (404) corresponding to the piston rod (4082), and the diameter of the through hole is larger than the diameter of the piston rod (4082); a piston (4081) is provided in the middle of the piston rod (4082), and the piston (4081) divides the interior of the outer tube (406) into a liquid chamber (405) and an air chamber (409), and the piston (4081) and the outer tube (406) and the piston rod (4082) and the floating end cover (403) are respectively dynamically sealed.

7. The accumulator sealing performance testing system simulating piston displacement according to claim 6, characterized in that: The floating end cover (403) is connected to the fixed end cover (404) by bolts. The floating end cover (403) is provided with a light avoidance hole corresponding to the bolt, and the diameter of the light avoidance hole is larger than the diameter of the bolt, so that the floating end cover (403) can slide relative to the fixed end cover (404).

8. The accumulator sealing performance testing system simulating piston displacement according to claim 1, characterized in that: The airtightness detection tool (413), the left lifting unit (200), the right lifting unit (300) and the simulated accumulator unit (400) are respectively arranged inside a low-temperature environment box (401); the low-temperature environment box (401) is connected to a second temperature sensor (116), and the second temperature sensor (116) is used to detect the temperature inside the low-temperature environment box (401).

9. The accumulator sealing performance testing system simulating piston displacement according to claim 1, characterized in that: A plurality of sealing plugs (414) are arranged on the peripheral side of the airtightness detection tool (413), and a third temperature sensor (411) and a third pressure sensor (412) are arranged between the airtightness detection tool (413) and the simulated accumulator unit (400).

10. A method for testing the sealing performance of a pressure accumulator by simulating piston displacement, using the sealing performance simulation test system for the pressure accumulator piston (4081) under displacement according to any one of claims 2 to 4, characterized in that: The following steps are involved: S1: Assemble the test system; S2: Adjust the test temperature of the test system to simulate the ambient temperature; S3: fixed seal boundary test; S31: adjusting the pressure of the relief valve (110) to the rated working pressure of the simulated accumulator, and starting the electric plunger pump (106) and the two-position three-way electromagnetic reversing valve (113); S32: close the manual stop valve (114) to hold the pressure in the simulated accumulator, immerse the gas seal detection tool (413) in the oil, and observe the air bubbles in the sealing plug (414); S4: Piston (4081) offset and deflection adjustment; S41: In the initial stage, the displacement detection values ​​of the left displacement sensor (205) and the right displacement sensor (305) are both zero, and the left lifting unit (200) and the right lifting unit (300) are adjusted respectively to make the displacement change values ​​of the left displacement sensor (205) and the right displacement sensor (305) consistent, so that the piston (4081) is offset, and the piston (4081) offset sealing boundary test is carried out; S42: adjusting the left lifting unit (200) and the right lifting unit (300) so that the displacement change values ​​of the left displacement sensor (205) and the right displacement sensor (305) are inconsistent, so that the piston (4081) inside the simulated accumulator unit (400) is deflected, and a piston (4081) deflection sealing boundary test is carried out; S5: sealing boundary test under piston (4081) offset and deflection; S51: adjust the pressure of the overflow valve (110) to the rated working pressure of the simulated accumulator, start the electric plunger pump (106), the two-position three-way electromagnetic reversing valve (113) and the manual stop valve (114); S52: recording the pressure of the liquid chamber (405) and the gas chamber (409) of the simulated accumulator unit (400), setting a cycle test, and collecting the number of times the two-position three-way electromagnetic reversing valve (113) is energized based on the counter (112), which is the number of working cycles of the simulated accumulator; S53: After the test is completed, the pressure data of the liquid chamber (405) and the air chamber (409) are compared and analyzed to obtain the sealing conditions of the piston (4081) at different offset deflections.

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