A test apparatus and method for secondary seal sealing performance, friction

Abstract

This invention relates to a testing apparatus for the sealing performance and frictional force of a secondary seal, comprising a sealing performance device, a load application device, and a media supply system. The sealing performance device is used to install the secondary seal and, in conjunction with the media supply system, performs room temperature airtightness and cryogenic liquid tightness tests on the secondary seal. The load application device, assisted by the media supply system, applies tensile / compressive axial loads to the sealing performance device and measures the frictional force of the secondary seal within the sealing performance device. When performing room temperature airtightness or cryogenic liquid tightness tests on the secondary seal, the media supply system provides room temperature air or cryogenic liquid nitrogen to the sealing performance device; when performing frictional force tests on the secondary seal, it supplies gas to the load application device. This invention also relates to a testing method for the sealing performance and frictional force of the secondary seal. This invention can obtain accurate leakage rates and simultaneously acquire the frictional force of the secondary seal to accurately assess the operating opening pressure of a detachable seal.

Description

Technical Field

[0001] This invention belongs to the field of cryogenic sealing test technology for liquid rocket engines, and relates to a test device and method for the sealing performance and friction force of a detachable combined sealing pair. Background Technology

[0002] With the development of aerospace technology, major spacefaring nations around the world have proposed the development of heavy-lift launch vehicles, and high-thrust rocket engines have become the trend of future aerospace development. The dynamic sealing function of the hydrogen turbine pump in a hydrogen-oxygen liquid rocket engine primarily aims to isolate the pump-end medium from the turbine cavity. However, with increasing requirements for reliability and load-bearing capacity in rocket system development, traditional floating ring seals no longer offer advantages.

[0003] The detachable combination seal with automatic disengagement function can achieve sealing of different cavities during the pre-cooling stage and automatically disengage under pressure when the engine starts, improving the reliability of the dynamic seal. A spring-loaded sealing ring is used as a secondary seal in the detachable combination seal to ensure good elasticity and sealing performance at low temperatures.

[0004] For the secondary seal, its structural form, materials, and fitting tolerances affect the operating opening pressure of the detachable combined seal. If the operating opening pressure of the detachable seal (i.e., the frictional force of the secondary seal) cannot be accurately assessed, the dynamic sealing performance of the engine's hydrogen turbopump will be affected, potentially leading to severe wear and failure of the detachable seal. Therefore, it is essential to conduct experimental research on the frictional performance and sealing performance of the detachable seal's secondary seal to provide data support for obtaining the detachment pressure of the detachable seal, thereby providing data and theoretical support for engine development and flight. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and to propose a test device and method for the sealing performance and friction force of secondary seals.

[0006] The solution of the present invention is:

[0007] In a first aspect, the present invention provides a testing device for the sealing performance and friction force of a secondary seal, comprising a sealing performance device, a load application device, and a medium supply system;

[0008] Sealing performance device: used to install the secondary seal and work with the media supply system to perform room temperature air tightness and low temperature liquid tightness tests on the secondary seal;

[0009] Load application device: With the assistance of the media supply system, it applies tensile / compressive axial loads to the sealing performance device and measures the frictional force of the secondary seal in the sealing performance device;

[0010] Medium supply system: used to supply room temperature air or cryogenic liquid nitrogen to the sealing performance device when conducting room temperature air tightness or cryogenic liquid tightness tests on the sub-seal; used to supply gas to the load application device when conducting friction force tests on the sub-seal.

[0011] Preferably, the sealing device includes housing assembly I, housing assembly II, sealing bushing, retaining ring, first secondary seal, and second secondary seal;

[0012] Housing assembly I and housing assembly II are fastened together by bolts, and a sealing aluminum gasket II is installed between them to achieve radial sealing. A sealing bushing is installed in the integral structure composed of housing assembly I and housing assembly II. A first set of seals is installed between housing assembly I and the sealing bushing, and a second set of seals is installed between housing assembly II and the sealing bushing. A retaining ring is installed between the first set of seals and the second set of seals to achieve axial positioning of the first set of seals and the second set of seals. Four through holes are evenly distributed along the circumference of the retaining ring. A groove is machined on the top of the sealing bushing.

[0013] Preferably, a first medium inflow channel and a first medium outflow channel are provided inside the side wall of the housing assembly I, and both the first medium inflow channel and the first medium outflow channel are in contact with the through hole of the retaining ring; a first blow-out port and a first discharge port are provided on the end face of the housing assembly I, and both the first blow-out port and the first discharge port are connected to a first discharge cavity, which is formed by a sealing bushing and the housing assembly I;

[0014] The housing assembly II has a second blow-out port and a second vent outlet on its side wall. Both the second blow-out port and the second vent outlet are connected to the second venting cavity, which is formed by the sealing bushing, the housing assembly II, and the load application device.

[0015] Preferably, the load application device includes a piston cylinder cover, a piston cylinder cover gasket, a piston cylinder, a piston, a connecting nozzle, a support shell, a displacement sensor mounting bracket, a heating element, a force transmission head, a force transmission rod, a docking plate, a force sensor, a displacement sensor, and a diaphragm box.

[0016] The top of the force transmission rod is threaded to the sealing bushing, and its tail is fastened to the force transmission head by bolts. The force transmission head is fastened to one end of the heating body by thread, and the other end of the heating body is fastened to one end of the force sensor by thread. The other end of the force sensor is fastened to the piston by thread.

[0017] The piston is installed in the piston cylinder with a clearance fit. An O-ring is installed between the piston and the piston cylinder for axial sealing of the compressed gas. The piston cylinder is connected to one end of the support shell, and bolts are used to fasten the mating plate and the other end of the support shell to the housing assembly II.

[0018] The displacement sensor mounting bracket is fixed between the force sensor and the heating element. The displacement sensor is mounted on the displacement sensor mounting bracket by bolts, and the displacement monitoring head of the displacement sensor is in contact with the piston cylinder.

[0019] One end flange of the diaphragm box is fastened to the mating plate by bolts; the other end flange of the diaphragm box is fastened to the force transmission rod by bolts.

[0020] The piston cylinder cover is fixed to the tail of the piston cylinder, and a piston cylinder cover gasket is provided between the piston cylinder and the piston cylinder cover. A connecting nozzle is provided on the side wall of the piston cylinder, and the connecting nozzle communicates with the first air chamber inside the piston cylinder.

[0021] Preferably, a diaphragm gasket II is provided between the diaphragm box and the docking plate; and a diaphragm gasket I is provided between the diaphragm box and the force transmission rod.

[0022] Preferably, the heating element has a groove, and the heating belt and temperature sensor are embedded in the groove through a filler adhesive.

[0023] Preferably, the piston cylinder cover is machined with cylinder inlet and outlet ports that communicate with the second air chamber.

[0024] Preferably, the media supply system includes a cryogenic liquid nitrogen / air media supply system, a loading media supply system, and a gas purging system;

[0025] The cryogenic liquid nitrogen / air medium supply system includes a cryogenic pressure vessel, a cryogenic pneumatic shut-off valve, a first cryogenic manual shut-off valve, and a second cryogenic manual shut-off valve; the cryogenic pressure vessel is connected to a first medium inflow channel through a first pipeline, and the first pipeline is sequentially equipped with a cryogenic pneumatic shut-off valve, a first cryogenic manual shut-off valve, and a second cryogenic manual shut-off valve along the medium flow direction.

[0026] The gas purging system includes a nitrogen cylinder, a first manual shut-off valve, a first pressure reducing valve, and a second manual shut-off valve; the nitrogen cylinder is connected to the first purging port and the second purging port through a second pipeline, and the first manual shut-off valve, the first pressure reducing valve, and the second manual shut-off valve are sequentially installed on the second pipeline along the direction of medium flow.

[0027] The loading medium supply system includes a gas cylinder, a third manual shut-off valve, a second pressure reducing valve, a fourth manual shut-off valve, and a two-position five-way solenoid valve; the gas cylinder is connected to the inlet of the two-position five-way solenoid valve through a third pipeline, and the first outlet of the two-position five-way solenoid valve is connected to the inlet and outlet of the cylinder of the load application device; the third pipeline is provided with the third manual shut-off valve, the second pressure reducing valve, and the fourth manual shut-off valve in sequence along the medium flow direction.

[0028] The discharge pipeline of the first discharge outlet is equipped with a fifth manual shut-off valve and a first gas volume flow meter in sequence; the discharge pipeline of the second discharge outlet is equipped with a sixth manual shut-off valve and a second gas volume flow meter; and the discharge pipeline of the first medium discharge channel is equipped with a third low-temperature manual shut-off valve.

[0029] Secondly, the present invention provides a test method for the sealing performance of a secondary seal, including a room temperature air tightness test and a low temperature liquid tightness test for the secondary seal.

[0030] The method for the room temperature airtightness test is as follows:

[0031] Close the second manual shut-off valve and the third cryogenic manual shut-off valve;

[0032] Open the cryogenic pneumatic shut-off valve, the first cryogenic manual shut-off valve, and the second cryogenic manual shut-off valve. The cryogenic pressure vessel is filled with compressed air. The compressed air enters the cavity between the first and second secondary seals through the first medium inflow channel.

[0033] Open the fifth and sixth manual shut-off valves;

[0034] Compressed air flows through the first outlet and sequentially through the fifth manual shut-off valve and the first gas volume flow meter, and through the second outlet and sequentially through the sixth manual shut-off valve and the second gas volume flow meter. Based on the measurement data of the first gas volume flow meter and the second gas volume flow meter, the sealing performance of the first and second seals under normal temperature compressed air medium is tested.

[0035] The low-temperature liquid tightness test method is as follows:

[0036] Close the fifth and sixth manual shut-off valves;

[0037] Open the cryogenic pneumatic shut-off valve, the first cryogenic manual shut-off valve, and the second cryogenic manual shut-off valve. The cryogenic pressure vessel is filled with liquid nitrogen medium, which enters the cavity between the first and second secondary seals through the first medium inflow channel.

[0038] Open the third low-temperature manual shut-off valve, close the second manual shut-off valve, and then pre-cool the test equipment through the first medium outflow channel;

[0039] When the temperature of the cavity between the first and second secondary seals reaches -196 degrees Celsius, close the third cryogenic manual shut-off valve.

[0040] Open the fifth and sixth manual shut-off valves;

[0041] Cryogenic liquid nitrogen flows sequentially through the first outlet to the fifth manual shut-off valve and the first gas volume flow meter, and then through the second outlet to the sixth manual shut-off valve and the second gas volume flow meter. Based on the measurement data from the first and second gas volume flow meters, the sealing performance of the first and second sets of seals under cryogenic liquid nitrogen medium is tested.

[0042] Preferably, the heating belt is externally connected to a temperature controller, which controls whether the heating belt works. When the temperature collected by the temperature sensor is below 30°C, the temperature controller outputs a voltage signal to the heating belt to start working. When the temperature collected by the temperature sensor is above 40°C, the temperature controller stops outputting signals to the heating belt, and the heating belt stops heating, thus ensuring that the force sensor and displacement sensor always work within the normal temperature range.

[0043] Thirdly, the present invention provides a test method for the friction force of a secondary seal, including a room temperature friction force test and a low temperature friction force test of the secondary seal;

[0044] The method for testing friction at room temperature is as follows:

[0045] Open the cryogenic pneumatic shut-off valve, the first cryogenic manual shut-off valve, the second cryogenic manual shut-off valve, the third manual shut-off valve, and the fourth manual shut-off valve;

[0046] The cryogenic pressure vessel is filled with air at different pressures. The air enters the cavity between the first and second secondary seals through the first medium inflow channel, so that the pressure in the cavity between the first and second secondary seals traverses the design pressure.

[0047] Under each design stress:

[0048] Control the two-position five-way solenoid valve to connect the nozzle to the loading medium supply system. Slowly adjust the intake pressure through the pressure reducing valve until the piston begins to move axially, causing the power sensor, displacement sensor, heating element, force transmission head, force transmission rod, and sealing bushing to move axially as a whole.

[0049] During the process of adjusting the pressure reducing valve, the force sensor and displacement sensor synchronously collect and record data at the same sampling frequency and send it to the host computer.

[0050] The host computer plots the curves of force F collected by the force sensor versus time history t and the curves of force F collected by the force sensor versus displacement X collected by the displacement sensor, respectively, to obtain the frictional force of the first and second seals.

[0051] After the friction test under the current design pressure is completed, the two-position five-way solenoid valve is activated to exhaust the pipe nozzle and allow air to enter the cylinder inlet and outlet ports, pushing the piston to start moving axially in the opposite direction. This causes the force sensor, displacement sensor, heating element, force transmission head, force transmission rod, and sealing bushing to move axially as a whole until the end face of the sealing bushing contacts the sealing housing assembly I.

[0052] The low-temperature friction force test method is as follows:

[0053] Close the fifth and sixth manual shut-off valves;

[0054] Open the cryogenic pneumatic shut-off valve, the first cryogenic manual shut-off valve, and the second cryogenic manual shut-off valve. The cryogenic pressure vessel is filled with liquid nitrogen medium, which enters the cavity between the first and second secondary seals through the first medium inflow channel.

[0055] Open the third low-temperature manual shut-off valve, close the second manual shut-off valve, and then pre-cool the test equipment through the first medium outflow channel;

[0056] When the temperature of the cavity between the first and second secondary seals reaches -196 degrees Celsius, close the third cryogenic manual shut-off valve.

[0057] Open the first manual shut-off valve and the second manual shut-off valve, and adjust the first pressure reducing valve to ensure that the nitrogen inlet pressure of the first purge port and the second purge port is less than 0.1 MPa;

[0058] Open the third and fourth manual shut-off valves;

[0059] The cryogenic pressure vessel is filled with liquid nitrogen at different pressures. The liquid nitrogen enters the cavity between the first and second secondary seals through the first medium inflow channel, so that the pressure in the cavity between the first and second secondary seals traverses the design pressure.

[0060] Under each design stress:

[0061] Control the two-position five-way solenoid valve to connect the nozzle to the loading medium supply system. Slowly adjust the intake pressure through the pressure reducing valve until the piston begins to move axially, causing the power sensor, displacement sensor, heating element, force transmission head, force transmission rod, and sealing bushing to move axially as a whole.

[0062] During the process of adjusting the pressure reducing valve, the force sensor and displacement sensor synchronously collect and record data at the same sampling frequency and send it to the host computer.

[0063] The host computer plots the curves of force F collected by the force sensor versus time history t and the curves of force F collected by the force sensor versus displacement X collected by the displacement sensor, respectively, to obtain the frictional force of the first and second seals.

[0064] After the friction test under the current design pressure is completed, the two-position five-way solenoid valve is activated, which causes the pipe nozzle to exhaust air and the cylinder inlet and outlet to enter air, pushing the piston to start moving axially in the opposite direction. This causes the force sensor, displacement sensor, heating element, force transmission head, force transmission rod, and sealing bushing to move axially as a whole until the end face of the sealing bushing contacts the sealing housing assembly I.

[0065] Preferably, the method by which the host computer obtains the frictional force of the first and second seals is as follows:

[0066] Remove the first and second seals from the sealing performance device;

[0067] The loading medium supply system is used to pressurize and exhaust the load application device through the pipe nozzle and cylinder inlet and outlet, causing the sealing bushing to move axially. The axial tensile and compressive stiffness values ​​of the diaphragm box under no-load conditions are measured by the force sensor, and the curve of force collected by the force sensor and displacement collected by the displacement sensor under no-load conditions is obtained.

[0068] By using the curves of force F from the force sensor and displacement X from the displacement sensor obtained during the installation of the first and second seals, and the curves of force from the force sensor and displacement from the displacement sensor under no-load conditions, the actual frictional force values ​​of the first and second seals can be obtained.

[0069] Preferably, the heating belt is externally connected to a temperature controller, which controls whether the heating belt works. When the temperature collected by the temperature sensor is below 30°C, the temperature controller outputs a voltage signal to the heating belt to start working. When the temperature collected by the temperature sensor is above 40°C, the temperature controller stops outputting signals to the heating belt, and the heating belt stops heating, thus ensuring that the force sensor and displacement sensor always work within the normal temperature range.

[0070] The advantages of this invention compared to the prior art are:

[0071] (1) The test equipment of the present invention integrates the loading device and the sealing test device. It adopts diaphragm sealing, gasket sealing and nitrogen blowing out of the device, which can effectively avoid moisture absorption during the low temperature test and accurately measure the sealing effect of the detachable combined sealing pair at low temperature and normal temperature, and obtain accurate leakage amount.

[0072] (2) The test equipment of the present invention uses force sensors, displacement sensors and axial heating technology to ensure that the force sensors and displacement sensors always operate within the normal temperature range. At the same time, the force sensor measurement takes into account the stiffness factor of the diaphragm, and the measurement results are more accurate. By combining the measured friction force and displacement value of the secondary seal, more accurate friction force-displacement curve and friction force-time curve of the secondary seal can be obtained, which provides accurate data support for the performance evaluation of the maximum static friction force and dynamic friction force of the secondary seal, so as to accurately evaluate the working opening pressure of the detachable seal.

[0073] (3) The piston cylinder of the load application device of the present invention is provided with an air inlet and outlet at both ends. The air inlet and outlet are controlled by a two-position five-way solenoid valve. While realizing the automatic control of loading, the loading device can also travel in two directions, which greatly improves the efficiency of the test. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of the test equipment;

[0075] Figure 2 This is a two-dimensional structural diagram of the bushing;

[0076] Figure 3 Schematic diagram of the media supply system and testing equipment;

[0077] Figure 4 This is a partial structural diagram of the heating zone. Detailed Implementation

[0078] The invention will now be further described with reference to the accompanying drawings.

[0079] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0080] The structure of the secondary seal sealing performance and friction force testing equipment of this invention is as follows: Figure 1 As shown, it includes a sealing performance device for installing the secondary seal and measuring the sealing performance of the secondary seal, a load application device for applying axial force and measuring the frictional performance of the secondary seal, and a media supply system.

[0081] Sealing performance device: used to install the secondary seal and work with the media supply system to perform room temperature air tightness and low temperature liquid tightness tests on the secondary seal.

[0082] Load application device: With the assistance of the media supply system, it applies tensile / compressive axial loads to the sealing performance device and measures the frictional force of the secondary seal in the sealing performance device.

[0083] Medium supply system: used to supply room temperature air or cryogenic liquid nitrogen to the sealing performance device when conducting room temperature air tightness or cryogenic liquid tightness tests on the sub-seal; used to supply gas to the load application device when conducting friction force tests on the sub-seal.

[0084] The sealing performance measurement device for the secondary seal includes housing assembly I19, sealing housing assembly II14, sealing bushing 15, retaining ring 17, first secondary seal 18, and second secondary seal 16.

[0085] The first auxiliary seal 18 is installed between the housing assembly I19 and the sealing sleeve 15, and the second auxiliary seal 16 is installed between the housing assembly II14 and the sealing sleeve 15. A retaining ring 17 is installed between the first auxiliary seal 18 and the second auxiliary seal 16 to achieve axial positioning of the two seals. The housing assembly I19 and housing assembly II14 are fastened together by bolts 32, and a sealing aluminum gasket II33 is installed between them to achieve radial sealing. Four through holes are evenly distributed circumferentially on the retaining ring 17.

[0086] The surface roughness Ra of the contact surfaces of the housing assembly I19, housing assembly II14 and the first auxiliary seals 18, 16 is no greater than 0.2; the cross-sectional shape of the sealing bushing 15 is as follows: Figure 2 As shown, its cross-section is a cylindrical rotating structure similar to an I-beam, and the surface roughness Ra of its outer circle is no greater than 0.2. The top of the sealing bushing 15 is machined with a groove.

[0087] The housing assembly I19 has a first medium inflow channel and a first medium outflow channel in its side wall, both of which are in contact with the through hole of the retaining ring 17. The housing assembly I19 has a first blow-out port and a first discharge port on its end face, both of which are connected to a first discharge cavity, which is formed by the sealing bushing 15 and the housing assembly I19. The housing assembly II14 has a second blow-out port and a second discharge port in its side wall, both of which are connected to a second discharge cavity, which is formed by the sealing bushing 15, the housing assembly II14, and a load application device.

[0088] The structure of the load application device mainly includes piston cylinder cover 1, piston cylinder cover gasket 2, piston cylinder 3, piston 4, screw-in connector 5, support shell 6, displacement sensor fixing bracket 7, heating element 8, force transmission head 9, force transmission rod 10, diaphragm gasket I11, diaphragm gasket II12, docking plate 13, force sensor 24, displacement sensor 25, and diaphragm 28.

[0089] The top threaded portion of the force transmission rod 10 of the load application device is connected to the sealing bushing 15, and its upper part is fastened to the force transmission head 9 by bolts 26. The force transmission head 9 is fastened to the heating body 8 by threaded connection, the heating body 8 is fastened to the force sensor 24 by threaded connection, and the force sensor 24 is fastened to the piston 4 by threaded connection.

[0090] The piston 4 and piston cylinder 3 of the load application device are clearance-fitted, and O-ring I 20 and O-ring II 21 are installed between the piston 4 and piston cylinder 3 for axial sealing of compressed gas.

[0091] The piston cylinder 3 of the load application device is connected to the support shell 6 by bolts 22 and nuts 23, and bolts 29 fasten the mating plate 13, the support shell 6 and the sealing shell assembly II14.

[0092] The displacement sensor 25 is bolted to the displacement sensor mounting bracket 7, which is fixed between the force sensor 24 and the heating element 8. The displacement sensor head of the displacement sensor 25 is in contact with the piston cylinder 3.

[0093] One end flange of the diaphragm box 28 is connected and fastened to the docking plate 13 by bolts 30, and a diaphragm box gasket II 12 is provided between the two; one end flange of the diaphragm box 28 is connected and fastened to the force transmission rod 10 by bolts 27, and a diaphragm box gasket I11 is provided between the two.

[0094] The diaphragm 28 has a pressure-bearing capacity of not less than 0.5 MPa, can operate in a low-temperature environment of -196℃, has a maximum stroke of 26 mm, and the pressure and tension generated at its maximum compression and maximum tension positions are less than 50 N. A sealing aluminum gasket I 31 is provided between the mating plate 13 and the housing assembly II 14.

[0095] The secondary seal sealing performance and friction force testing device requires an external connection piping system. The two-dimensional schematic diagram of the testing device system is shown below. Figure 3 As shown, its main component is the media supply system.

[0096] The media supply system includes three types. The first type is a cryogenic liquid nitrogen media supply system composed of a cryogenic pressure vessel 34, a cryogenic pneumatic shut-off valve 35, a cryogenic manual shut-off valve 36, and a cryogenic manual shut-off valve 37, as well as a compressed air media supply system. The cryogenic pressure vessel 34 is connected to the first media inflow channel through a first pipeline. The cryogenic pneumatic shut-off valve 35, the cryogenic manual shut-off valve 36, and the cryogenic manual shut-off valve 37 are sequentially arranged along the media flow direction on the first pipeline.

[0097] When the medium required for the test of the sealing performance and friction force of the secondary seal is compressed air, the cryogenic pressure vessel 34 is filled with compressed air and the compressed air is supplied to the test device through the first medium inflow channel of the test equipment; when the medium required for the test of the sealing performance and friction force of the secondary seal is liquid nitrogen, the cryogenic pressure vessel 34 is filled with cryogenic liquid nitrogen and the liquid nitrogen is supplied to the test device through the first medium inflow channel of the test equipment.

[0098] The second type of media supply system is a loading media supply system, which consists of a gas cylinder 40, a manual shut-off valve 41, a pressure reducing valve 42, a manual shut-off valve 43, and a two-position five-way solenoid valve 44. The gas cylinder 40 is connected to the inlet of the two-position five-way solenoid valve 44 via a third pipeline, and the first outlet of the two-position five-way solenoid valve 44 is connected to the inlet and outlet of the cylinder of the load application device; the manual shut-off valve 41, the pressure reducing valve 42, and the manual shut-off valve 43 are sequentially arranged along the media flow direction on the third pipeline.

[0099] The maximum pressure of the gas cylinder 40 is not less than 5MPa, and the internal gas medium is at room temperature. The gas medium can be compressed nitrogen, helium, air, etc.

[0100] The opening pressure of the two-position five-way solenoid valve 44 is no greater than 0.1 MPa, and the maximum working pressure is greater than 2 MPa.

[0101] The third type of media supply system is a gas purging system consisting of a nitrogen cylinder 47, a manual shut-off valve 48, a pressure reducing valve 49, and a manual shut-off valve 50. The nitrogen cylinder 47 is connected to the first purging port and the second purging port through a second pipeline. The manual shut-off valve 48, the pressure reducing valve 49, and the manual shut-off valve 50 are sequentially installed on the second pipeline along the media flow direction.

[0102] The discharge pipeline of the first discharge outlet is equipped with a manual shut-off valve 46 and a first gas volume flow meter 45 in sequence; the discharge pipeline of the second discharge outlet is equipped with a manual shut-off valve 39 and a second gas volume flow meter 38; and the discharge pipeline of the first medium discharge channel is equipped with a low temperature manual shut-off valve 51.

[0103] The working principle of the secondary seal sealing performance and friction force testing device is divided into two types: one is the static pressure sealing performance test working principle, and the other is the dynamic pressure friction force test working principle.

[0104] The purpose of the static pressure sealing performance test is to measure the sealing performance of the secondary seals 16 and 18 under different pressures of compressed air and liquid nitrogen.

[0105] During the compressed air medium air tightness test, the cryogenic pressure vessel 34 is filled with compressed air. The compressed air enters the cavity between the two secondary seals 16 and 18 through the medium inlet, and then flows through the first outlet sequentially through the manual shut-off valve 46 and the gas volume flow meter 45, and through the second outlet sequentially through the manual shut-off valve 39 and the gas volume flow meter 38. The manual shut-off valve 50 is closed, and the cryogenic manual shut-off valve 51 at the medium outlet is closed, thereby realizing the sealing performance test of the second secondary seals 16 and 18 under normal temperature compressed air medium.

[0106] During the cryogenic medium airtightness test, the cryogenic pressure vessel 34 is filled with liquid nitrogen. The liquid nitrogen enters the cavity between the two sub-seals 16 and 18 through the inlet. The cryogenic manual shut-off valve 51 is opened, while the manual shut-off valve 50 is closed. Then, the test device is pre-cooled through the outlet. When the temperature of the cavity between the two sub-seals 16 and 18 reaches -196 degrees Celsius, the cryogenic manual shut-off valve 51 is closed. Then, the liquid nitrogen flows through the first outlet sequentially through the manual shut-off valve 46 and the gas volume flow meter 45, and through the second outlet sequentially through the manual shut-off valve 39 and the gas volume flow meter 38, thus completing the sealing performance test of the sub-seals 16 and 18 under cryogenic liquid nitrogen medium.

[0107] The purpose of the dynamic pressurization friction test is to test the axial friction force of the sub-seals 16 and 18 under different pressures of compressed air and liquid nitrogen.

[0108] The working principle of the dynamic pressure friction test is as follows: After completing the air tightness test of compressed air or liquid nitrogen medium, the system is kept in working state, and the manual shut-off valves 41 and 43 in the loading medium supply system are opened. The two-position five-way solenoid valve 44 is controlled to operate, so that the connecting pipe 5 is connected to the loading medium supply system. The intake pressure is slowly adjusted through the pressure reducing valve 42 until the piston 4 begins to move axially, and the pulling force sensor 24, displacement sensor 25, heating element 8, force transmission head 9, force transmission rod 10, and sealing bushing 15 move axially as a whole.

[0109] During the process of adjusting the pressure reducing valve 42, the force sensor 24 and the displacement sensor 25 synchronously collect and record data at the same sampling frequency, and respectively draw the curve of force F collected by force sensor 24 versus time history t and the curve of force F collected by force sensor 24 versus displacement X collected by displacement sensor 25 through the display terminal.

[0110] The force F collected by the force sensor 24 should be processed. The processing method is to pressurize and exhaust the air through the cylinder inlet and outlet to make the bushing 15 move axially, and measure the axial tensile and compressive stiffness values ​​of the diaphragm 28 under no-load conditions through the force sensor. The stiffness value of the diaphragm is then subtracted from the formula design of the force sensor to obtain the true friction force value of the secondary seals 16 and 18.

[0111] When conducting the dynamic pressurization friction test with liquid nitrogen medium, manual medium valves 48 and 50 should be opened, and the nitrogen inlet pressure at the first and second purging ports of the test device should be less than 0.1 MPa by adjusting the pressure reducing valve 49.

[0112] During the dynamic pressurization friction test, after each friction test at a pressure (the set pressure of the secondary seal, adjusted by the gas pressure of the cryogenic pressure vessel 34), the two-position five-way solenoid valve 44 is activated to exhaust the pipe nozzle and allow air to enter the cylinder inlet and outlet, pushing the piston 4 to begin moving axially in the opposite direction. This, in turn, pushes the power sensor 24, displacement sensor 25, heating element 8, force transmission head 9, force transmission rod 10, and sealing bushing 15 to move axially as a whole until the end face of the sealing bushing 15 contacts the sealing housing assembly I19.

[0113] The heating element 8 is provided with a groove 52, such as Figure 4 As shown, the heating belt and temperature sensor are embedded into the heating element 8 through the filling adhesive in the groove. The heating belt is externally connected to a temperature controller, which controls whether the heating belt works. When the temperature collected by the temperature sensor is below 30°C, the temperature controller outputs a voltage signal to the heating belt to start working; when the temperature collected by the temperature sensor is above 40°C, the temperature controller stops outputting signals to the heating belt, and the heating belt stops heating, ensuring that the force sensor 24 and displacement sensor 25 operate within the normal temperature range.

[0114] In this invention, the manual shut-off valve does not emphasize low temperature, meaning it can operate at both low and normal temperatures.

[0115] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A test apparatus for secondary seal sealing performance, friction, characterized by: This includes sealing devices, load application devices, and media supply systems; Sealing performance device: used to install the secondary seal and work with the media supply system to perform room temperature air tightness and low temperature liquid tightness tests on the secondary seal; Load application device: With the assistance of the media supply system, it applies tensile / compressive axial loads to the sealing performance device and measures the frictional force of the secondary seal in the sealing performance device; Medium supply system: used to supply room temperature air or cryogenic liquid nitrogen to the sealing performance device when conducting room temperature air tightness or cryogenic liquid tightness tests on the sub-seal; used to supply gas to the load application device when conducting friction force tests on the sub-seal. The load application device includes a piston cylinder cover (1), a piston cylinder cover gasket (2), a piston cylinder (3), a piston (4), a connecting nozzle (5), a support shell (6), a displacement sensor mounting bracket (7), a heating element (8), a force transmission head (9), a force transmission rod (10), a docking plate (13), a force sensor (24), a displacement sensor (25), and a diaphragm (28). The top of the force transmission rod (10) is threaded to the sealing bushing (15), and its tail is fastened to the force transmission head (9) by bolts. The force transmission head (9) is fastened to one end of the heating body (8) by thread, and the other end of the heating body (8) is fastened to one end of the force sensor (24) by thread, and the other end of the force sensor (24) is fastened to the piston (4) by thread. The piston (4) is installed in the piston cylinder (3) with clearance fit. An O-ring is installed between the piston (4) and the piston cylinder (3) for axial sealing of compressed gas. The piston cylinder (3) is connected to one end of the support shell (6), and bolts (29) fasten the other end of the mating plate (13) and the support shell (6) to the housing assembly II (14). The displacement sensor mounting bracket (7) is fixed between the force sensor (24) and the heating element (8). The displacement sensor (25) is installed on the displacement sensor mounting bracket (7) by bolts. The displacement monitoring head of the displacement sensor (25) is in contact with the piston cylinder (3). One end flange of the diaphragm box (28) is connected and fastened to the mating plate (13) by bolts (30); the other end flange of the diaphragm box (28) is connected and fastened to the force transmission rod (10) by bolts (27); The piston cylinder cover (1) is fixed at the tail of the piston cylinder (3). A piston cylinder cover gasket (2) is provided between the piston cylinder (3) and the piston cylinder cover (1). A connecting nozzle (5) is provided on the side wall of the piston cylinder. The connecting nozzle (5) is connected to the first air chamber inside the piston cylinder (3). The heating element (8) is provided with a groove (52), and the heating belt and temperature sensor are embedded in the groove through a filler adhesive; The media supply system includes a cryogenic liquid nitrogen / air media supply system, a loading media supply system, and a gas purging system; The cryogenic liquid nitrogen / air medium supply system includes a cryogenic pressure vessel (34), a cryogenic pneumatic shut-off valve (35), a first cryogenic manual shut-off valve (36), and a second cryogenic manual shut-off valve (37). The cryogenic pressure vessel (34) is connected to the first medium inflow channel through a first pipeline. The first pipeline is provided with the cryogenic pneumatic shut-off valve (35), the first cryogenic manual shut-off valve (36), and the second cryogenic manual shut-off valve (37) in sequence along the medium flow direction. The gas purging system includes a nitrogen cylinder (47), a first manual shut-off valve (48), a first pressure reducing valve (49), and a second manual shut-off valve (50). The nitrogen cylinder (47) is connected to the first purging port and the second purging port through a second pipeline. The first manual shut-off valve (48), the first pressure reducing valve (49), and the second manual shut-off valve (50) are sequentially arranged along the medium flow direction on the second pipeline. The loading medium supply system includes a gas cylinder (40), a third manual shut-off valve (41), a second pressure reducing valve (42), a fourth manual shut-off valve (43), and a two-position five-way solenoid valve (44). The gas cylinder (40) is connected to the inlet of the two-position five-way solenoid valve (44) through a third pipeline. The first outlet of the two-position five-way solenoid valve (44) is connected to the inlet and outlet of the cylinder of the load application device. The third pipeline is provided with the third manual shut-off valve, the second pressure reducing valve, and the fourth manual shut-off valve in sequence along the medium flow direction. The first outlet outlet is equipped with a fifth manual shut-off valve (46) and a first gas volume flow meter (45) in sequence on the outlet pipe. The second outlet outlet is equipped with a sixth manual shut-off valve (39) and a second gas volume flow meter (38) on the outlet pipe. The first medium outlet outlet is equipped with a third low temperature manual shut-off valve (51) on the outlet pipe.

2. A test apparatus for secondary seal sealing performance, friction force according to claim 1, characterized in that: The sealing device includes housing assembly I (19), housing assembly II (14), sealing bushing (15), retaining ring (17), first secondary seal (18), and second secondary seal (16). Housing assembly I (19) and housing assembly II (14) are fastened together by bolts, and a sealing aluminum gasket II (33) is installed between them to achieve radial sealing. A sealing bushing (15) is installed in the integral structure composed of housing assembly I (19) and housing assembly II (14). A first secondary seal (18) is installed between housing assembly I (19) and sealing bushing (15), and a second secondary seal (16) is installed between housing assembly II (14) and sealing bushing (15). A retaining ring (17) is installed between the first secondary seal (18) and the second secondary seal (16) to achieve axial positioning of the first secondary seal (18) and the second secondary seal (16). Four through holes are evenly distributed along the circumference of the retaining ring (17). A groove is machined on the top of the sealing bushing (15).

3. The testing equipment for the sealing performance and friction force of a secondary seal according to claim 2, characterized in that: The housing assembly I (19) has a first medium inflow channel and a first medium outflow channel in its side wall. The first medium inflow channel and the first medium outflow channel are in contact with the through hole of the retaining ring (17). The housing assembly I (19) has a first blow-out port and a first discharge port on its end face. The first blow-out port and the first discharge port are in communication with the first discharge cavity. The first discharge cavity is formed by the sealing bushing (15) and the housing assembly I (19). The housing assembly II (14) has a second blow-out port and a second vent port on its side wall. The second blow-out port and the second vent port are both connected to the second vent cavity. The second vent cavity is formed by the sealing bushing (15), the housing assembly II (14), and the load application device.

4. The testing equipment for the sealing performance and friction force of a secondary seal according to claim 1, characterized in that: A diaphragm gasket II (12) is provided between the diaphragm box (28) and the docking plate (13); a diaphragm gasket I (11) is provided between the diaphragm box (28) and the force transmission rod (10).

5. The testing equipment for the sealing performance and friction force of a secondary seal according to claim 1, characterized in that: The piston cylinder cover (1) is machined with cylinder inlet and outlet ports that communicate with the second air chamber.

6. The test method for the testing equipment for testing the sealing performance and friction force of a secondary seal as described in any one of claims 1-5, characterized in that, This includes room temperature airtightness tests and low temperature liquid tightness tests for the secondary seal; The method for the room temperature airtightness test is as follows: Close the second manual shut-off valve (50) and the third low-temperature manual shut-off valve (51). Open the cryogenic pneumatic shut-off valve (35), the first cryogenic manual shut-off valve (36), and the second cryogenic manual shut-off valve (37). The cryogenic pressure vessel (34) is filled with compressed air. The compressed air enters the cavity between the first secondary seal (18) and the second secondary seal (16) through the first medium inflow channel. Open the fifth manual shut-off valve (46) and the sixth manual shut-off valve (39); Compressed air flows through the first outlet and sequentially through the fifth manual shut-off valve (46) and the first gas volume flow meter (45), and through the second outlet and sequentially through the sixth manual shut-off valve (39) and the second gas volume flow meter (38). Based on the measurement data of the first gas volume flow meter (45) and the second gas volume flow meter (38), the sealing performance test of the first secondary seal (18) and the second secondary seal (16) under normal temperature compressed air medium is carried out. The low-temperature liquid tightness test method is as follows: Close the fifth manual shut-off valve (46) and the sixth manual shut-off valve (39); Open the cryogenic pneumatic shut-off valve (35), the first cryogenic manual shut-off valve (36), and the second cryogenic manual shut-off valve (37). The cryogenic pressure vessel (34) is filled with liquid nitrogen medium. The liquid nitrogen medium enters the cavity between the first secondary seal (18) and the second secondary seal (16) through the first medium inflow channel. Open the third low-temperature manual shut-off valve (51), close the second manual shut-off valve (50), and then pre-cool the test equipment through the first medium outflow channel; When the cavity temperature between the first secondary seal (18) and the second secondary seal (16) reaches -196 degrees Celsius, close the third low-temperature manual shut-off valve (51). Open the fifth manual shut-off valve (46) and the sixth manual shut-off valve (39); Cryogenic liquid nitrogen flows through the first outlet and sequentially through the fifth manual shut-off valve (46) and the first gas volume flow meter (45), and through the second outlet and sequentially through the sixth manual shut-off valve (39) and the second gas volume flow meter (38). Based on the measurement data of the first gas volume flow meter (45) and the second gas volume flow meter (38), the sealing performance test of the first secondary seal (18) and the second secondary seal (16) under cryogenic liquid nitrogen medium is carried out.

7. The test method according to claim 6, characterized in that, The heating belt is externally connected to a temperature controller, which controls whether the heating belt works. When the temperature collected by the temperature sensor is below 30°C, the temperature controller outputs a voltage signal to the heating belt to start working. When the temperature collected by the temperature sensor is above 40°C, the temperature controller stops outputting a signal to the heating belt, and the heating belt stops heating, ensuring that the force sensor (24) and displacement sensor (25) always work within the normal temperature range.

8. The test method for a test apparatus for testing the sealing performance and friction force of a secondary seal as described in any one of claims 1-5, characterized in that, This includes room temperature friction tests and low temperature friction tests for the secondary seal; The method for testing friction at room temperature is as follows: Open the cryogenic pneumatic shut-off valve (35), the first cryogenic manual shut-off valve (36), the second cryogenic manual shut-off valve (37), the third manual shut-off valve (41), and the fourth manual shut-off valve (43). The cryogenic pressure vessel (34) is filled with air at different pressures. The air enters the cavity between the first secondary seal (18) and the second secondary seal (16) through the first medium inflow channel, so that the pressure in the cavity between the first secondary seal (18) and the second secondary seal (16) traverses the design pressure. Under each design stress: Control the two-position five-way solenoid valve (44) to connect the pipe nozzle (5) to the loading medium supply system. Slowly adjust the intake pressure through the pressure reducing valve (42) until the piston (4) begins to move axially, causing the power sensor (24), displacement sensor (25), heating element (8), force transmission head (9), force transmission rod (10), and sealing bushing (15) to move axially as a whole. During the adjustment of the pressure reducing valve (42), the force sensor (24) and displacement sensor (25) synchronously collect and record data at the same sampling frequency and send it to the host computer. The host computer plots the force collected by the force sensor (24). F With the passage of time t The curve, the force collected by the force sensor (24) F Displacement acquired by displacement sensor (25) X The curve is used to obtain the frictional force of the first seal (18) and the second seal (16); After the friction test under the current design pressure is completed, the two-position five-way solenoid valve (44) is activated, the pipe nozzle (5) is vented, the cylinder inlet and outlet are vented, and the piston (4) is pushed to start moving axially in the opposite direction, thereby pushing the force sensor (24), displacement sensor (25), heating element (8), force transmission head (9), force transmission rod (10), and sealing bushing (15) to move axially as a whole until the end face of the sealing bushing (15) contacts the sealing housing assembly I (19); The low-temperature friction force test method is as follows: Close the fifth manual shut-off valve (46) and the sixth manual shut-off valve (39); Open the cryogenic pneumatic shut-off valve (35), the first cryogenic manual shut-off valve (36), and the second cryogenic manual shut-off valve (37). The cryogenic pressure vessel (34) is filled with liquid nitrogen medium. The liquid nitrogen medium enters the cavity between the first secondary seal (18) and the second secondary seal (16) through the first medium inflow channel. Open the third low-temperature manual shut-off valve (51), close the second manual shut-off valve (50), and then pre-cool the test equipment through the first medium outflow channel; When the cavity temperature between the first secondary seal (18) and the second secondary seal (16) reaches -196 degrees Celsius, close the third low-temperature manual shut-off valve (51). Open the first manual shut-off valve (48) and the second manual shut-off valve (50), and adjust the first pressure reducing valve (49) to ensure that the nitrogen inlet pressure of the first purge port and the second purge port is less than 0.1 MPa; Open the third manual shut-off valve (41) and the fourth manual shut-off valve (43); The cryogenic pressure vessel (34) is filled with liquid nitrogen at different pressures. The liquid nitrogen enters the cavity between the first secondary seal (18) and the second secondary seal (16) through the first medium inflow channel, so that the pressure in the cavity between the first secondary seal and the second secondary seal traverses the design pressure. Under each design stress: Control the two-position five-way solenoid valve (44) to connect the pipe nozzle (5) to the loading medium supply system. Slowly adjust the intake pressure through the pressure reducing valve (42) until the piston (4) begins to move axially, causing the power sensor (24), displacement sensor (25), heating element (8), force transmission head (9), force transmission rod (10), and sealing bushing (15) to move axially as a whole. During the process of adjusting the pressure reducing valve (42), the force sensor (24) and displacement sensor (25) synchronously collect and record data at the same sampling frequency and send it to the host computer; The host computer plots the force collected by the force sensor (24). F With the passage of time t The curve, the force collected by the force sensor (24) F Displacement acquired by displacement sensor (25) X The curve is used to obtain the frictional force of the first seal (18) and the second seal (16); After the friction test under the current design pressure is completed, the two-position five-way solenoid valve (44) is activated, the pipe nozzle (5) is vented, the cylinder inlet and outlet are vented, and the piston (4) is pushed to start moving axially in the opposite direction, thereby pushing the force sensor (24), displacement sensor (25), heating element (8), force transmission head (9), force transmission rod (10), and sealing bushing (15) to move axially as a whole until the end face of the sealing bushing (15) contacts the sealing housing assembly I (19).

9. The test method according to claim 8, characterized in that, The method by which the host computer obtains the frictional force of the first seal (18) and the second seal (16) is as follows: Remove the first and second seals (16) from the sealing performance device. The load application device is pressurized and vented by the loading medium supply system through the pipe nozzle and the cylinder inlet and outlet, causing the sealing bushing (15) to move axially. The axial tensile and compressive stiffness values ​​of the diaphragm (28) under no-load conditions are measured by the force sensor, and the curve of force collected by the force sensor (24) and displacement collected by the displacement sensor (25) under no-load conditions is obtained. Force sensor (24) force obtained during the installation of the first seal (18) and the second seal (16) F Displacement with displacement sensor (25) X The curves of the force of the force sensor (24) and the displacement of the displacement sensor (25) under no-load conditions are used to obtain the actual friction values ​​of the first seal (18) and the second seal (16).

10. The test method according to claim 9, characterized in that, The heating belt is externally connected to a temperature controller, which controls whether the heating belt works. When the temperature collected by the temperature sensor is below 30°C, the temperature controller outputs a voltage signal to the heating belt to start working. When the temperature collected by the temperature sensor is above 40°C, the temperature controller stops outputting a signal to the heating belt, and the heating belt stops heating, ensuring that the force sensor (24) and displacement sensor (25) always work within the normal temperature range.

Images