Overflow valve for booster delivery system of launch vehicle and its preloading assembly method

Abstract

The present invention provides an overflow valve for a pressurization and transfer system of a launch vehicle and a preloading and assembling method thereof, which relates to the technical field of fluid working systems and includes: a piston, a forced chamber, a piston rod, a bellows and a main valve housing; the bellows is installed in the main valve housing, and a forced chamber is arranged on the main valve housing, and the forced chamber is located inside the bellows; the piston rod and the piston are connected to form a combined body, and the combined body is installed on the bellows and the forced chamber; a ring-shaped convex structure is arranged on the valve seat part of the main valve housing, and a ring-shaped groove is arranged on the non-metallic surface of the piston, and the ring-shaped convex and the ring-shaped groove are in contact connection to form a spigot sealing structure; the piston rod and the main valve housing are in clearance fit to form a guiding pair. The overflow valve of the present invention can use high-pressure gas after the rocket is recovered to forcibly open the valve through the forced chamber and complete the safe discharge of the residual pressurized propellant in the rocket storage tank.

Description

Technical Field

[0001] The present invention relates to the technical field of fluid working systems, and in particular, to an overflow valve for a booster transfer system of a launch vehicle and a preloading assembly method thereof, especially an overflow valve for a booster transfer system of a reusable launch vehicle and a preloading assembly method thereof, and particularly a large-diameter overflow valve for a reusable cryogenic launch vehicle booster transfer system and a preloading assembly method thereof. Background Art

[0002] With the continuous development of China's space industry, cryogenic propellants such as liquid hydrogen and liquid oxygen are widely used, and the demand for large-diameter cryogenic valves is increasing day by day. Cryogenic overflow valves are widely used in the booster transfer systems of cryogenic rockets. Its working principle is that when the pressure in the rocket propellant tank exceeds the design value, the overflow valve opens to release the pressure and ensure the safety of the tank. When the tank pressure is lower than the set value, the overflow valve closes and seals to prevent the leakage of cryogenic propellants. For reusable launch vehicles, after the rocket is recovered, it is necessary to safely release the pressurized residual propellants inside the tank. However, the pressure of this part of the propellants is usually lower than the design value of the overflow valve opening pressure. Therefore, traditional overflow valves cannot meet the requirements for the release of low-pressure propellants. In addition, for the valve to be reusable, the overflow valve needs to have better sealing performance at low temperatures. Therefore, the vigorous development of reusable launch vehicles has put forward new requirements for large-diameter overflow valves, including low-pressure active release, high-reliability sealing, and long cryogenic life.

[0003] Large-diameter cryogenic overflow valves for launch vehicles are characterized by complex product structures, numerous assembly processes, and harsh service conditions. The debugging of cryogenic valves produced by traditional assembly methods is difficult, and under extreme working conditions, the product sealing performance is difficult to meet the requirements. The core reason is that during the assembly process of the overflow valve, due to the difficult-to-guarantee machining accuracy of large-sized inserted parts and the uneven force during the assembly process, etc., the metal / non-metal sealing pair of the valve cannot be fully engaged to form an effective line seal after assembly, resulting in local leakage and sealing failure. Subsequently, the pressure in the rocket propellant tank is too low during the launch mission process, the propellant flow rate and the rocket thrust are insufficient, and ultimately the rocket launch fails.

[0004] The assembly and debugging process of the overflow valve is complex and there are numerous assembly processes. If leakage occurs, the entire valve needs to be disassembled, the sealing components need to be replaced, and the assembly and debugging need to be carried out again. This results in poor stability of the assembly quality of large-diameter overflow valve products, low production efficiency, and insufficient batch qualification rate, leading to repetitive labor and long repair times, and it is difficult to meet the increasing space mission requirements. Summary of the Invention

[0005] Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide an overflow valve for a booster transfer system of a launch vehicle and a preloading assembly method thereof.

[0006] An overflow valve for a booster transfer system of a launch vehicle according to the present invention includes: a piston, a forced chamber, a piston rod, a bellows, and a main valve housing;

[0007] The bellows is installed in the main valve housing, and the forced chamber is provided on the main valve housing. The forced chamber is located inside the bellows, and the wall surface of the forced chamber is connected to the piston rod by a thread;

[0008] The piston rod and the piston are connected to form a combination body, and the combination body is installed on the bellows and the forced chamber, and the main valve can be fully opened by introducing compressed air into the forced chamber;

[0009] An annular protrusion structure is provided on the valve seat portion of the main valve housing, and an annular groove is provided on the non-metallic surface of the piston. The annular protrusion and the annular groove are in contact connection to form a stop seal structure;

[0010] The piston rod is in clearance fit with the main valve housing to form a guide pair.

[0011] Preferably, the depth of the annular groove is 0.1 mm - 0.15 mm;

[0012] The annular protrusion is a circular arc chamfer, and the diameter of the circular arc chamfer is 0.2 mm - 0.4 mm.

[0013] Preferably, the unilateral fit clearance between the piston rod and the main valve housing is 0.01 mm - 0.1 mm;

[0014] The ratio of the length of the guiding surface of the piston rod to the guiding diameter is not less than 1.5.

[0015] Preferably, it further includes: a pre-pressing forming tooling and a dial indicator;

[0016] The pre-pressing forming tooling can be installed on the main valve housing and pre-press the piston to generate an indentation on the non-metallic surface of the piston in contact with the annular protrusion, and the indentation forms the annular groove;

[0017] The dial indicator is used to measure the downward pressing depth of the piston end face of the piston and the depth of the indentation;

[0018] After the pre-pressing is completed, the pre-pressing forming tooling can be disassembled from the main valve housing.

[0019] Preferably, the pre-pressing forming tooling includes: an adjusting screw, a centering screw cap, and a stop block;

[0020] The adjusting screw is threadedly connected to the centering screw cap, and the stop block is detachably arranged at one end of the adjusting screw;

[0021] The centering screw cap and the stop block are used to be installed in the forcing cavity;

[0022] When the adjusting screw rotates on the centering screw cap, the adjusting screw can drive the stop block to move in the forcing cavity, and the stop block drives the combination body, thereby pre-pressing the non-metallic surface of the piston.

[0023] Preferably, a lower spherical surface is arranged at one end of the adjusting screw;

[0024] An inner conical surface adapted to the lower spherical surface is arranged at the central position of the stop block.

[0025] Preferably, an external thread adapted to the internal thread of the forcing cavity is arranged on the outer surface of the centering screw cap;

[0026] An internal thread adapted to the external thread of the adjusting screw is arranged on the inner surface of the centering screw cap.

[0027] Preferably, a knurled surface and a relief groove are further arranged on the outer surface of the used centering screw cap.

[0028] The present invention also provides a pre-pressing assembly method for an overflow valve, which is used for the overflow valve of the booster conveying system of a launch vehicle, and specifically includes the following steps:

[0029] Step S1: Assemble the main valve of the overflow valve;

[0030] Step S2: Select a matching centering screw cap and stop block according to the thread size on the forcing cavity of the overflow valve;

[0031] Step S3: Sequentially install the centering screw cap and the stop block into the forcing cavity from top to bottom, and make the stop block contact the piston rod. The centering screw cap is fixed in the forcing cavity, and the stop block can move in the forcing cavity;

[0032] Step S4: Screw the adjusting screw into the centering screw cap, and make the adjusting screw move downward so that the lower spherical surface of the adjusting screw abuts against the central position of the stop block;

[0033] Step S5: Rotate the adjusting screw to make it displace downward, so that the non-metallic surface on the piston is pre-pressed with the annular protrusion. During the pre-pressing process, the depth of the downward pressure of the piston end face is measured by the dial indicator ejector rod of the dial indicator against the piston end face of the piston from the outlet of the main valve housing of the overflow valve, and the downward displacement distance of the adjusting screw is determined;

[0034] Step S6: When the downward displacement distance of the adjusting screw reaches a preset value, the adjusting screw is kept stationary, and the pre-pressure is maintained for a preset time, so that a complete indentation is formed on the non-metallic surface of the piston;

[0035] Step S7: rotating the adjusting screw rod to move it upward until the spherical surface at the lower end of the adjusting screw rod and the stopper are no longer subjected to force;

[0036] Step S8: measuring again by the bell-type dial indicator to determine whether the depth of the indentation is the preset value, if so, completing the pre-pressing, if not, moving the adjustment screw downward again to perform pre-pressing until the depth of the indentation is the preset value;

[0037] Step S9: screw the adjusting screw, the centering screw cap, and the stopper out of the forced cavity, take out the pre-pressing forming tooling, continue to assemble the valve body of the relief valve, and determine the torque;

[0038] Step S10: Debugging and checking the air tightness of the overflow valve.

[0039] Preferably, the step S1 specifically comprises the following steps:

[0040] Step S1.1: Connect the piston and the piston rod through threads, and install the bellows and the forced chamber to form an integral structure;

[0041] Step S1.2: Install the whole structure into the main valve housing. Before installation, use a lifting tool to support the piston end face of the piston to prevent the non-metallic surface on the piston from being crushed by the stop on the main valve housing during the installation process.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The present invention arranges a forced cavity structure inside the bellows and introduces a certain pressure of gas into the forced cavity, so that the overflow valve can be actively opened when the pressure is lower than the designed opening pressure, thereby realizing the discharge of low-pressure residual propellant of the repeatable rocket.

[0044] 2. The pre-pressing forming process of the present invention is to pre-press the non-metallic surface on the piston with the help of pre-pressing forming tooling to form a stop seal structure, and measure the depth of the pre-pressing indentation by a bell-type dial indicator. This method gets rid of the risk of product disassembly and replacement of parts, and solves the problem of low one-time qualified rate in assembly and debugging of large-caliber relief valves at a relatively low cost, reduces the scrap rate of parts, and improves the low-temperature sealing performance and operating life of the relief valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0046] Figure 1Schematic diagram of the overflow valve and pre - pressing forming tooling for the pressurization and transportation system of a launch vehicle according to the present invention;

[0047] Figure 2 Schematic diagram of the pre - pressing forming tooling for the overflow valve of the pressurization and transportation system of a launch vehicle according to the present invention;

[0048] Figure 3 Schematic diagram of the disassembly of the assembly relationship of the pre - pressing forming tooling for the overflow valve of the pressurization and transportation system of a launch vehicle according to the present invention;

[0049] Figure 4 Schematic diagram of the pre - pressing and measurement of the pre - pressing forming tooling for the overflow valve of the pressurization and transportation system of a launch vehicle according to the present invention on the valve body;

[0050] Figure 5 Schematic diagram of the pre - pressing depth of the pre - pressing forming tooling for the overflow valve of the pressurization and transportation system of a launch vehicle according to the present invention;

[0051] Figure 6 Schematic diagram of the complete indentation of the pre - pressing forming tooling for the overflow valve of the pressurization and transportation system of a launch vehicle according to the present invention after pre - pressing.

[0052] As shown in the figure:

[0053] Adjusting screw 1, lower spherical surface 101, centering gland 2, stop block 3, inner conical surface 301, bell - type dial indicator 4, dial indicator ejector rod 5, piston end face 6, main valve housing outlet 7, stop - mouth sealing structure 8, piston 9, non - metallic surface 901, forced cavity 10, piston rod 11, bellows 12, main valve housing 13, back - pressure cavity 14, back - pressure cavity gland thread 15. Specific embodiments

[0054] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several changes and improvements can still be made. These all belong to the protection scope of the present invention.

[0055] Embodiment 1:

[0056] As Figures 1-6As shown in the figure, this embodiment provides a relief valve for the pressurization and transfer system of a launch vehicle, including: a piston 9, a forcing chamber 10, a piston rod 11, a bellows 12, and a main valve housing 13; the bellows 12 is installed inside the main valve housing 13, a forcing chamber 10 is provided on the main valve housing 13, the forcing chamber 10 is located inside the bellows 12, and the wall surface of the forcing chamber 10 is fixedly connected to the piston rod 11 through threads; the piston rod 11 and the piston 9 are connected to form an assembly, and the assembly is installed on the bellows 12 and the forcing chamber 10, and the main valve can be fully opened by introducing compressed air into the forcing chamber 10; a ring-shaped convex structure is provided on the valve seat part of the main valve housing 13, and a ring-shaped groove is provided on the non-metallic surface of the piston 9, and the ring-shaped convex and the ring-shaped groove are in contact connection to form a spigot seal structure 8; the piston rod 11 and the main valve housing 13 are in clearance fit to form a guiding pair.

[0057] The depth of the ring-shaped groove is 0.1 mm - 0.15 mm; the ring-shaped convex is a circular arc chamfer, and the diameter of the circular arc chamfer is 0.2 mm - 0.4 mm. The unilateral fit clearance between the piston rod 11 and the main valve housing 13 is 0.01 mm - 0.1 mm; the ratio of the guiding surface length to the guiding diameter of the piston rod 11 is not less than 1.5.

[0058] The relief valve further includes: a pre-pressing forming tooling and a dial indicator 4; the pre-pressing forming tooling can be installed on the main valve housing 13 and pre-press the piston 9 to generate an indentation on the non-metallic surface 901 of the piston 9 in contact with the ring-shaped convex, and the indentation forms a ring-shaped groove; the dial indicator 4 is used to measure the downward pressing depth of the piston end face 6 of the piston 9 and the depth of the indentation; after the pre-pressing is completed, the pre-pressing forming tooling can be disassembled from the main valve housing 13.

[0059] The pre-pressing forming tooling includes: an adjusting screw 1, a centering screw cap 2, and a stop block 3; the adjusting screw 1 is in threaded connection with the centering screw cap 2, and the stop block 3 is detachably arranged at one end of the adjusting screw 1; the centering screw cap 2 and the stop block 3 are used to be installed inside the forcing chamber 10; when the adjusting screw 1 rotates on the centering screw cap 2, the adjusting screw 1 can drive the stop block 3 to move inside the forcing chamber 10, and the stop block 3 drives the assembly, and then pre-presses the non-metallic surface of the piston 9. A lower spherical surface 101 is provided at one end of the adjusting screw 1; an inner conical surface 301 adapted to the lower spherical surface is provided at the central position of the stop block 3. An external thread adapted to the internal thread of the forcing chamber 10 is provided on the outer surface of the centering screw cap 2; an internal thread adapted to the external thread of the adjusting screw 1 is provided on the inner surface of the centering screw cap 2. A knurled surface and a relief groove are also provided on the outer surface of the centering screw cap 2.

[0060] The relief valve of this embodiment can use high-pressure gas to forcibly open the valve through the forcing chamber after the rocket is recovered, and complete the safe discharge of the residual pressurized propellant in the rocket storage tank.

[0061] The pre-pressed forming structure of this embodiment can effectively improve the sealing performance and operating life of the overflow valve at low temperatures, and meet the requirements of reusability.

[0062] The overflow valve of this embodiment has a forced opening function. When the tank pressure is lower than the design value of the overflow valve, the existing overflow valve cannot be opened and the tank pressure cannot be released. However, the present application can force the valve to open by introducing compressed gas into the forced chamber of the overflow valve, thereby achieving pressure release under low pressure.

[0063] Existing overflow valves have the defect of insufficient low-temperature sealing effect, low pass rate, and lack the ability to actively open and release under low pressure. In addition, similar cryogenic valves of NASA in the United States use a large amount of precision / ultra-precision processing technology to ensure the sealing reliability under low temperature, which is very costly.

[0064] This embodiment also provides a pre-pressurization assembly method of a relief valve, wherein the relief valve used in a booster delivery system of a launch vehicle specifically comprises the following steps:

[0065] Step S1: Assemble the main valve of the overflow valve; specifically, it includes the following steps:

[0066] Step S1.1: Connect the piston 9 and the piston rod 11 by threads, and install the bellows 12 and the forced chamber 10 to form an integral structure;

[0067] Step S1.2: Install the whole structure into the main valve housing 13. Before installation, use a lifting tool to support the piston end face 6 of the piston 9 to prevent the non-metallic surface of the piston 9 from being crushed by the stopper on the main valve housing 13 during the installation process;

[0068] Step S2: selecting a matching centering screw cap 2 and stopper 3 according to the thread size on the forced cavity 10 of the relief valve;

[0069] Step S3: The centering nut 2 and the stopper 3 are sequentially installed into the forced cavity 10 from top to bottom, and the stopper 3 is in contact with the piston rod 11, the centering nut 2 is fixed in the forced cavity 10, and the stopper 3 can move in the forced cavity 10;

[0070] Step S4: screw the adjusting screw 1 into the centering screw cover 2, and move the adjusting screw 1 downward so that the spherical surface of the lower end of the adjusting screw 1 abuts against the center position of the stopper 3;

[0071] Step S5: rotating the adjusting screw 1 to make it move downward, so that the non-metallic surface on the piston 9 and the annular protrusion are pre-pressed. During the pre-pressing process, the dial gauge push rod 5 of the bell dial gauge 4 pushes against the piston end face 6 of the piston 9 from the outlet 7 of the main valve housing of the relief valve, and the downward pressing depth of the piston end face 6 is measured to determine the downward displacement distance of the adjusting screw 1;

[0072] Step S6: When the downward displacement distance of the adjusting screw 1 reaches the preset value, keep the adjusting screw 1 stationary and apply pre-pressure for a preset time to form a complete indentation on the non-metallic surface of the piston 9;

[0073] Step S7: Rotate the adjusting screw 1 to make it move upward until the lower spherical surface of the adjusting screw 1 is not stressed by the stopper 3;

[0074] Step S8: Measure again with the dial indicator 4 to determine whether the depth of the indentation is the preset value. If so, the pre-pressure is completed. If not, move the adjusting screw 1 downward again for pre-pressure until the depth of the indentation reaches the preset value;

[0075] Step S9: Unscrew the adjusting screw 1, centering cover 2, and stopper 3 from the forcing chamber 10, remove the pre-forming tooling, continue to assemble the valve body of the overflow valve, and apply a specified torque;

[0076] Step S10: Debug the overflow valve and check its airtightness.

[0077] Embodiment 2:

[0078] Those skilled in the art can understand this embodiment as a more specific illustration of Embodiment 1.

[0079] This embodiment provides a main valve of a general-purpose large-bore overflow valve for aerospace and its pre-press assembly method. The main valve includes: a main valve housing 13, a bellows 12, a piston 9, a piston rod 11, etc.

[0080] The piston 9, piston rod 11, and bellows 12 are inside the main valve housing 13. There is a ring-shaped protrusion structure in the valve seat part of the main valve housing, and there is a ring-shaped groove on the non-metallic surface of the piston. The ring-shaped protrusion and the ring-shaped groove are approximately conformal to form a spigot seal structure 8. The piston rod and the housing are in clearance fit to form a guiding pair, and the unilateral fit clearance is within a specific range. The length of the guiding surface of the piston rod and the guiding diameter are not less than a specific value.

[0081] The pre-press assembly method mainly includes the assembly process and pre-forming process of the main valve. In the main valve assembly process, the piston 9 and the piston rod 11 are screwed and connected into the bellows 12 and the forcing chamber 10, and then the whole is installed on the main valve housing 13. Before installation, a jacking tooling needs to be used to hold the end face of the piston 9 to prevent the non-metallic on the piston 9 from being damaged by the spigot on the main valve housing 13 during the installation process. In the pre-forming process, a pre-forming tooling is used to pre-press the non-metallic on the piston 9, so as to machine a ring-shaped groove on the surface of the non-metallic sealing surface, and the pre-press depth is measured by a dial indicator.

[0082] For the rabbet seal structure described above, the depth of the non-metallic annular groove is 0.1 - 0.15 mm, the annular metal protrusion structure is processed into a circular arc chamfer with a chamfer diameter of 0.2 - 0.4 mm. The annular groove and the annular protrusion have approximately conformal contours. The annular groove and the annular protrusion are in line contact sealing at the bottom of the annular groove. The annular groove has a guiding function during the assembly process of the overflow valve, guiding the annular protrusion to slide into the annular groove to form an effective rabbet seal.

[0083] The piston rod and the housing are in clearance fit, with a unilateral clearance of 0.01 - 0.1 mm. The ratio of the length of the piston rod guiding surface to the guiding diameter is not less than 1.5.

[0084] This embodiment also provides a preloading assembly method for a large - caliber general - purpose aerospace overflow valve. The outer surface of the centering screw cap of the tooling used has a knurled surface, a relief groove, an external thread, and an internal thread adapted to the external thread of the adjusting screw.

[0085] The surface of the adjusting screw of the tooling used is an external thread, with an external hexagon at one end and a spherical surface at the other end.

[0086] The stopper of the tooling used is cylindrical, with a flat surface at one end and an internal conical surface at the other end.

[0087] The preloading assembly method for the main valve of the large - caliber general - purpose aerospace overflow valve described above includes the following steps:

[0088] S1. Select a matching centering screw cap and stopper according to the thread size on the back - pressure chamber of the main valve of the overflow valve;

[0089] S2. When the adjusting screw rotates clockwise and moves downward, a clock - type dial indicator is used to measure the preloading depth.

[0090] Embodiment 3:

[0091] Those skilled in the art can understand this embodiment as a more specific description of Embodiment 1.

[0092] This embodiment relates to the field of valve fluid working systems, and particularly relates to large - caliber valves represented by the new - generation launch vehicle. This embodiment provides an overflow valve for cryogenic rockets and its preloading and sealing method.

[0093] A cryogenic rocket relief valve provided in this embodiment includes: a main valve housing 13, a bellows 12, a piston 9, a piston rod 11, etc. The piston 9, the piston rod 11, and the bellows 12 are inside the main valve housing 13. There is an annular protrusion structure on the valve seat portion of the main valve housing, and there is an annular groove on the non-metallic surface of the piston. The annular protrusion and the annular groove are approximately conformal to form a stop sealing structure 8. The piston rod and the housing are clearance-matched to form a guide pair, and the single-sided clearance is within a specific range. The guide surface length and guide diameter of the piston rod are not less than specific values.

[0094] This embodiment also provides an assembly method of a large-caliber relief valve, which mainly includes:

[0095] With the slot on the end face of the piston 9 as the counter torque, the piston rod 11 is connected to the piston 9 by threads and a certain torque is applied to install it on the bellows 12 and the forced chamber 10 to form a component A. The component A is installed on the main valve housing 13 by bolt connection. Before installation, a lifting tool is required to support the end face of the piston 9 to prevent the non-metal on the piston 9 from being crushed by the stop on the main valve housing 13 during the installation process.

[0096] A circular groove is machined on the non-metallic surface of the piston using a pre-pressing tooling, and the pre-pressing tooling includes an adjusting screw 1, a centering screw cover 2, and a stopper 3. The hexagonal surface at one end of the adjusting screw 1 is used as a clamping surface for applying rotational force. The inner thread of the centering screw cover 2 is adapted to the outer thread of the adjusting screw 1, and can be rotated up and down therein to ensure the center position. The outer thread of the centering screw cover 2 is adapted to the inner thread of the forced cavity 10 of the valve body. The size of the stopper 3 should be adapted to the inner hole diameter of the forced cavity 10 of the main valve and the piston rod 11. The spherical surface at one end of the adjusting screw 1 is adapted to the inner conical surface of the stopper 3 to ensure the center position. When the adjusting screw 1 rotates clockwise to apply force to the stopper 3, the stopper 3 is evenly stressed on the valve body.

[0097] This embodiment also provides a method for using a pre-pressing tool for a general-purpose aerospace large-caliber relief valve, comprising the following steps:

[0098] According to the thread size on the forced cavity 10 of the relief valve main valve, select the matching centering screw cap and stopper. When the adjustment screw is rotated clockwise and moved downward to implement pre-pressure, the pre-pressure depth needs to be measured with a bell-type dial indicator.

[0099] The present embodiment provides a method for pre-pressing the main valve of a large-caliber aerospace general-purpose relief valve, which produces an indentation with controllable depth and high precision without affecting product performance. The pre-pressing method can pre-press the main valve sealing component of a general-purpose relief valve before commissioning to produce an optimal indentation, and the method prevents leakage at the sealing component of the valve in subsequent extreme working condition tests.

[0100] Embodiment 4:

[0101] Those skilled in the art may understand this embodiment as a more specific description of Embodiment 1.

[0102] This embodiment provides a main valve for a general-purpose large-caliber relief valve for aerospace and a pre-pressing assembly method thereof. The main valve includes a piston, a piston rod, a bellows, and a housing. The piston and the housing together form a stop seal structure. The piston rod and the housing are clearance-matched to form a guide effect. The aspect ratio of the guide surface is not less than 1.5.

[0103] During the valve assembly process, the main valve outlet sealing surface is pre-pressurized, which has high efficiency, is safer and more convenient. It can prevent the valve from leaking and secondary damage to the parts during the valve disassembly and assembly process, and avoid repair after installation and testing.

[0104] This embodiment is suitable for implementation during the assembly and debugging of a large-caliber relief valve.

[0105] The specific assembly method is as follows:

[0106] With the slot on the end face of the piston 9 as the counter torque, the piston rod 11 is connected to the piston 9 by threads and a certain torque is applied to install it on the bellows 12 and the forced chamber 10 to form a component A;

[0107] Install component A into the main valve housing 13 through bolt connection. Before installation, use a lifting tool to support the end face of the piston 9 to prevent the non-metal on the piston 9 from being crushed by the stop on the main valve housing 13 during the installation process.

[0108] The non-metal on the piston 9 is pre-pressed to a certain depth using a pre-pressing tool.

[0109] The most preferred method for measuring the pre-pressing depth is to use a bell-type dial indicator to measure and control the pre-pressing depth, and to pre-press the piston 9 to different depths with the help of a pre-pressing forming tool.

[0110] Pre-pressed tooling structure, such as Figure 2 As shown, it is composed of an adjusting screw 1, a centering screw cover 2, and a stopper 3.

[0111] The hexagonal surface at one end of the adjusting screw 1 is used as a clamping surface for applying a rotational force;

[0112] The inner thread of the centering screw cap 2 is adapted to the outer thread of the adjusting screw 1, and can be rotated up and down therein to ensure the center position;

[0113] The external thread of the centering screw cap 2 is adapted to the internal thread of the forced cavity 10 of the main valve;

[0114] The size of the stopper 3 should be adapted to the inner diameter of the main valve's forced cavity 10 and the piston rod 11, and the parallelism of the two end surfaces should be within 0.03mm;

[0115] One end spherical surface of the adjusting screw 1 is adapted to the inner conical surface of the stop block 3, and the central position is ensured.

[0116] When the adjusting screw 1 rotates clockwise to apply force to the stop block 3, the stop block 3 applies uniform force to the valve body.

[0117] S1. Select a matching centering screw cover and stop block according to the thread size on the back pressure chamber of the main valve of the overflow valve.

[0118] S2. When the adjusting screw rotates clockwise and displaces downward to apply preloading, a bell-type dial indicator is needed to measure the preloading depth.

[0119] Step 1: As Figure 1 shown, complete the assembly of the main valve of the overflow valve.

[0120] Step 2: As Figure 1 shown, install the tooling according to Figure 2 described, and fit the adjusting screw 1, centering screw cover 2, and stop block 3 into the thread 15 of the back pressure chamber screw cover. The lower end spherical surface of the adjusting screw 1 abuts against the stop block 3, and the central position is ensured.

[0121] The back pressure chamber 14 and the main valve inlet pressure are connected to the pilot valve through a pressure guiding pipe. The pilot valve determines whether to open the main valve according to the pressure difference between the main valve inlet pressure and the back pressure chamber pressure. The function of the forced chamber is to force the main valve to open after introducing compressed gas, ignoring the control of the pilot valve.

[0122] Step 3: As Figure 4 shown, rotate the adjusting screw 1 of the tooling downward to displace, so that the non-metallic sealing material on the piston 9 is preloaded with the spigot sealing structure 8.

[0123] Step 4: As Figure 4 and Figure 5 shown, during the preloading process, the dial indicator plunger 5 of the bell-type dial indicator 4 abuts against the piston end face 6 from the outlet 7 of the main valve housing of the overflow valve. The pressing depth of the piston end face 6 is the pressing depth of the non-metallic sealing material.

[0124] Step 5: As Figure 6 shown, preload for a certain time to preload the non-metallic sealing surface and the spigot sealing structure 8 to a complete indentation.

[0125] Step 6: Rotate the adjusting screw 1 of the tooling upward until the lower end spherical surface of the adjusting screw 1 is not stressed with the stop block 3.

[0126] Step 7: As Figure 4 and Figure 5 shown, measure again through the bell-type dial indicator to control the indentation at the optimal preloading depth.

[0127] Step 8: Rotate the centering screw cap 2 counterclockwise to loosen the adjusting screw 1 from the back pressure chamber screw cap thread 15, then invert the main valve and slide the stopper 3 out. In this way, the adjusting screw 1, centering screw cap 2, and stopper 3 are screwed out of the back pressure chamber screw cap thread, and the main valve pre-compression tooling is taken out, and the relief valve body is assembled and the torque is determined.

[0128] Step 9: Debug the overflow valve and check its air tightness.

[0129] After comparing the qualified rate, cost, efficiency, delivery cycle and other aspects before and after the improvement of the assembly process method in this embodiment, it is found that after the improvement of the assembly process method, the qualified rate of the first assembly test is increased to 85%-90%, which reduces the production and development costs, saves about 66% ((90%-30%) / 90%=66%) of the production cost, greatly improves the production efficiency, saves about 70% of the production time ((17-5) / 17=70.6%), shortens the delivery cycle of the model product, and shortens the production cycle from 10-17 months to 3-5 months, ensuring the high-quality delivery of the overflow valve.

[0130] The present invention provides a main valve of a general-purpose large-caliber relief valve for aerospace and a pre-pressing assembly method thereof. The valve seat and the piston surface of the main valve are provided with a conformal stop seal structure, and the piston rod and the housing are gap-matched to form a guide pair, and the single-side matching gap is within a specific range. The length of the piston rod guide surface and the guide diameter are not less than a specific value. The pre-pressing assembly method mainly includes an assembly process and a pre-pressing forming process of the relief valve main valve. The main valve assembly is to install the piston 9 and the piston rod 11 into the bellows 12 and the forced chamber 10 through threaded connection, and then install the whole into the main valve housing 13. Before installation, a lifting tool is required to support the end face of the piston 9 to prevent the non-metal on the piston 9 from being crushed by the stop on the main valve housing 13 during the installation process. The pre-pressing forming process is to pre-press the non-metal on the piston 9 with the help of the pre-pressing forming tool to form a stop seal structure, and measure the depth of the pre-pressing indentation by a bell-type dial indicator. This method gets rid of the risk of product disassembly and replacement of parts, solves the problem of low one-time qualified rate of large-caliber relief valve assembly and commissioning, and reduces the scrap rate of parts.

[0131] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0132] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. An overflow valve for a pressurized transfer system of a launch vehicle, characterized in that, Comprising: A piston (9), a forcing chamber (10), a piston rod (11), a bellows (12) and a main valve housing (13); The bellows (12) is installed inside the main valve housing (13), the forcing chamber (10) is arranged on the main valve housing (13), the forcing chamber (10) is located inside the bellows (12), and the wall surface of the forcing chamber (10) is connected to the piston rod (11) by threads; The piston rod (11) and the piston (9) are connected to form an assembly, and the assembly is installed on the bellows (12) and the forcing chamber (10), and the main valve can be fully opened by introducing compressed air into the forcing chamber (10); The valve seat part of the main valve housing (13) is provided with an annular convex structure, and the non-metallic surface of the piston (9) is provided with an annular groove, and the annular convex and the annular groove are in contact connection to form a rabbet seal structure (8); The piston rod (11) is in clearance fit with the main valve housing (13) to form a guiding pair; It also includes: a pre-forming tooling and a dial indicator (4); The pre-forming tooling can be installed on the main valve housing (13) and pre-press the piston (9) to generate an indentation on the non-metallic surface of the piston (9) in contact with the annular convex, and the indentation forms the annular groove; The dial indicator (4) is used to measure the pressing-down depth of the piston end face (6) of the piston (9) and the depth of the indentation; After the pre-pressing is completed, the pre-forming tooling can be disassembled from the main valve housing (13).

2. The overflow valve for the booster transfer system of a launch vehicle according to claim 1, characterized in that The depth of the annular groove is 0.1mm - 0.15mm; The annular convex is a circular arc chamfer, and the diameter of the circular arc chamfer is 0.2mm - 0.4mm.

3. The overflow valve for the pressurized transfer system of a launch vehicle according to claim 1, characterized in that, The unilateral fit clearance between the piston rod (11) and the main valve housing (13) is 0.01mm - 0.1mm; The ratio of the guiding surface length to the guiding diameter of the piston rod (11) is not less than 1.

5.

4. The overflow valve for the pressurization and transfer system of a launch vehicle according to claim 1, characterized in that, The pre-forming tooling includes: an adjusting screw (1), a centering screw cap (2) and a stop block (3); The adjusting screw (1) is in threaded connection with the centering screw cap (2), and the stop block (3) is detachably arranged at one end of the adjusting screw (1); The centering screw cap (2) and the stop block (3) are used to be installed inside the forcing chamber (10); When the adjusting screw (1) rotates on the centering screw cap (2), the adjusting screw (1) can drive the stop block (3) to move inside the forcing chamber (10), and the stop block (3) drives the assembly, thereby pre-pressing the non-metallic surface of the piston (9).

5. The overflow valve for the booster transfer system of a launch vehicle according to claim 4, characterized in that, One end of the adjusting screw (1) is provided with a lower spherical surface; The central position of the stop block (3) is provided with an inner conical surface adapted to the lower spherical surface; 6. The overflow valve for the pressurization and transfer system of a launch vehicle according to claim 4, characterized in that, The outer surface of the centering screw cap (2) is provided with an external thread adapted to the internal thread of the forcing chamber (10); The inner surface of the centering screw cap (2) is provided with an internal thread adapted to the external thread of the adjusting screw (1).

7. The overflow valve for the pressurization and transfer system of a launch vehicle according to claim 6, characterized in that, The outer surface of the centering screw cap (2) used is also provided with a knurled surface and a relief groove.

8. A preloading assembly method for an overflow valve, characterized in that, For the overflow valve used in the pressurization and delivery system of a launch vehicle as described in claim 4, the following steps are specifically included: Step S1: Assemble the main valve of the overflow valve. Step S2: Select a matching centering screw cap (2) and a stop block (3) according to the thread size on the forcing chamber (10) of the overflow valve. Step S3: Install the centering screw cap (2) and the stop block (3) into the forcing chamber (10) sequentially from top to bottom, and make the stop block (3) contact the piston rod (11). The centering screw cap (2) is fixed in the forcing chamber (10), and the stop block (3) can move in the forcing chamber (10). Step S5: Screw the adjusting screw (1) into the centering screw cap (2), and make the adjusting screw (1) move downward so that the lower spherical surface of the adjusting screw (1) presses against the central position of the stop block (3). Step S6: Rotate the adjusting screw (1) to make it displace downward so that the non-metallic surface on the piston (9) is pre-pressed against the annular protrusion. During the pre-pressing process, through the dial indicator plunger (5) of the dial indicator (4), press against the piston end face (6) of the piston (9) from the outlet (7) of the main valve housing of the overflow valve, measure the downward pressing depth of the piston end face (6), and determine the downward displacement distance of the adjusting screw (1). Step S7: When the downward displacement distance of the adjusting screw (1) reaches the preset value, keep the adjusting screw (1) stationary and maintain the pre-pressing for a preset time to form a complete indentation on the non-metallic surface of the piston (9). Step S8: Rotate the adjusting screw (1) to make it displace upward until the lower spherical surface of the adjusting screw (1) is not stressed with the stop block (3). Step S9: Measure again through the dial indicator (4) to judge whether the depth of the indentation is the preset value. If so, the pre-pressing is completed. If not, lower the adjusting screw (1) again for pre-pressing until the depth of the indentation is the preset value. Step S10: Unscrew the adjusting screw (1), the centering screw cap (2), and the stop block (3) from the forcing chamber (10), take out the pre-pressing forming tooling, continue to assemble the valve body of the overflow valve, and set the torque. Step S11: Debug and check the airtightness of the overflow valve.

9. The preloading assembly method of the overflow valve according to claim 8, characterized in that, The said step S1 specifically includes the following steps: Step S1.1: Connect the piston (9) and the piston rod (11) by thread and install them into the bellows (12) and the forcing chamber (10) to form an integral structure. Step S1.2: Install the integral structure into the main valve housing (13). Before installation, use a jacking tooling to press against the piston end face (6) of the piston (9) to prevent the non-metallic surface on the piston (9) from being damaged by the rabbet on the main valve housing (13) during the installation process.

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