A safety relief device for liquid rocket engines

Abstract

The application provides a safety pressure relief device for a liquid rocket engine, which comprises a piston, a valve core guide hole is formed in the piston, a valve core is installed in the valve core guide hole, the valve core comprises a valve core base, a top open auxiliary spring mounting hole is formed in the upper part of an auxiliary spring seat, and an auxiliary spring is installed in the auxiliary spring mounting hole; in the state that a sealing block is in contact with a valve seat for sealing, the auxiliary spring is compressed, so that a small stress state buffer gap is formed between the top end of the valve core base and the lower surface of a valve core limiting boss; an axial gap is arranged between the bottom end surface of the valve core base and the top end surface of a sealing seat. In the non-working state, the sealing stress borne by the plastic sealing surface of the valve core is small, so that the service life of the sealing surface is prolonged, and the long service life is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of aerospace engine, and relates to a liquid rocket engine, in particular to a safety pressure relief device for liquid rocket engine. BACKGROUND

[0002] The safety pressure relief device is normally closed, and when the pressure of the medium in the equipment or pipeline is higher than the specified value, the safety pressure relief device is used to prevent the pressure of the medium in the pipeline or equipment from exceeding the specified value by discharging the medium to the outside of the system. In the field of liquid rocket engine, the safety pressure relief device is a very important component in the power system, which functions to protect the system from overpressure.

[0003] The commonly used safety pressure relief device currently generally adopts a positive action structure, including metal hard sealing and non-metal sealing safety pressure relief devices, which have the advantages of simple structure, small opening and closing pressure difference, light weight, and are widely used in liquid rocket engine systems. Initially, the safety pressure relief device is generally applied to the gas medium pipeline or equipment, but with the continuous development of the aerospace gas self-pressurization technology, the safety pressure relief device is gradually applied to the propellant line. Due to the structural characteristics of the positive action safety pressure relief device, the medium acting area depends on the diameter of the valve seat, and the opening pressure and the valve seat diameter of the safety pressure relief device determine the size of the spring force. With the increase of the working pressure, the sealing specific pressure between the valve core and the valve seat decreases, and then leakage occurs. Even at the normal working pressure, it is difficult to completely prevent leakage, and a certain leakage is generally allowed in the gas line safety pressure relief device, with a leakage rate of ≤30 mL / s. However, if the safety pressure relief device of the liquid line system leaks, it will cause the waste of the pressurized propellant and the pollution of other equipment, and in severe cases, the leaked propellant may even explode, which seriously affects the working reliability and safety of the liquid rocket engine; especially in recent years, the mechanical environment of the liquid rocket engine system is becoming more and more severe, which causes the traditional positive action safety pressure relief device to easily have problems of excessive leakage, opening and closing pressure deviation after experiencing the impact mechanical environment, and cannot meet the requirements of the existing liquid rocket engine system. SUMMARY

[0004] In view of the deficiencies in the prior art, the purpose of the present application is to provide a safety pressure relief device for liquid rocket engine, which solves the technical problems of the positive action safety pressure relief device in the prior art that cannot be completely sealed at a small opening and closing pressure difference (0.2 MPa) and that has increased leakage and deviated opening and closing pressure after experiencing the impact mechanical environment.

[0005] In order to solve the above technical problems, the present application adopts the following technical solutions:

[0006] A kind of safety pressure relief device for liquid rocket engine, including valve body and piston assembly, the valve body includes valve body base body, piston assembly guide hole is arranged in valve body base body, valve body base body top of piston assembly guide hole is opened with valve body outlet, valve body outlet is coaxially connected with piston assembly guide hole and communicates, the end of valve body outlet is provided with valve seat, valve seat is located in piston assembly guide hole;Valve body base body is also opened with valve inlet along radial direction, valve inlet is connected with the inner wall of piston assembly guide hole close to top and communicates.

[0007] The piston assembly guide hole is installed with piston assembly, the piston assembly includes piston, the piston is integrally formed with pressure lead-in section, guide section and valve body limiting boss from top to bottom, the outer diameter of pressure lead-in section is smaller than that of guide section, and the outer diameter of guide section is smaller than that of valve body limiting boss;The cavity between pressure lead-in section and the inner wall of piston assembly guide hole communicates with valve inlet;The guide section is fitted in piston assembly guide hole;The valve body limiting boss can be limited by being abutted on the end face of the bottom end of piston assembly guide hole.

[0008] The valve core guide hole is opened in the piston, and the valve core is installed in the valve core guide hole, the valve core includes valve core base body, two flat channels are opened in the axial both sides of the valve core base body, and the flat channels form a medium flow channel with the valve core guide hole.

[0009] The valve core guide hole is opened with pressure lead-in ring groove on the inner wall close to top, a plurality of pressure lead-in holes are opened in the pressure lead-in ring groove along radial direction and pass through the pressure lead-in section, and the pressure lead-in holes communicate with valve inlet through piston assembly guide hole to flow medium.

[0010] The top of the pressure lead-in section of the piston is provided with valve core limiting boss, the top of the valve core guide hole is coaxially opened with sealing block guide hole passing through the valve core limiting boss, the inner diameter of the sealing block guide hole is smaller than that of the valve core guide hole, and the bottom of the valve core guide hole is coaxially opened with auxiliary spring seat mounting hole passing through the bottom of the piston, and the inner diameter of the auxiliary spring seat mounting hole is larger than that of the valve core guide hole.

[0011] The upper part of the valve core base body is opened with top-opened sealing block mounting hole, the sealing block mounting hole is installed with sealing block, the top end of the sealing block is higher than the top end of the valve core base body, and the sealing surface of the top end of the sealing block can contact and seal with valve seat through sealing block guide hole.

[0012] The auxiliary spring seat mounting hole is mounted with an auxiliary spring seat, the auxiliary spring seat comprises a sealing seat, a mounting seat and a connecting seat which are integrally formed from top to bottom, the outer diameter of the sealing seat is smaller than that of the mounting seat, and the outer diameter of the mounting seat is larger than that of the connecting seat; the sealing seat is inserted into the valve core guide hole, the mounting seat is inserted into the auxiliary spring seat mounting hole, and the shaft shoulder between the mounting seat and the sealing seat can be positioned on the inner end surface between the auxiliary spring seat mounting hole and the valve core guide hole.

[0013] The upper part of the auxiliary spring seat is provided with an auxiliary spring mounting hole which is open at the top, and the auxiliary spring is mounted in the auxiliary spring mounting hole.

[0014] In the state that the sealing block is in contact with the valve seat for sealing, the auxiliary spring is compressed by the valve core, so that the top end of the valve core base body and the lower surface of the valve core limiting boss have a small stress state buffer gap.

[0015] An axial gap is arranged between the bottom end surface of the valve core base body and the top end surface of the sealing seat.

[0016] The application also has the following technical features:

[0017] When the sealing specific pressure of the sealing block is less than or equal to 3 MPa, the sealing block is made of rubber material; when the sealing specific pressure of the sealing block is greater than 3 MPa, the sealing block is made of plastic material.

[0018] In the non-installed state that the sealing surface of the sealing block is not in contact with the valve seat for sealing, the distance of the axial gap is H; in the installed state that the sealing surface of the sealing block is in contact with the valve seat for sealing, the auxiliary spring is compressed to a small stress state buffer gap with a distance of 0.5 mm, and the distance of the axial gap is H-0.5 mm.

[0019] An outer sealing groove is formed on the outer wall of the guide section, an outer sealing ring is mounted in the outer sealing groove, and the outer sealing ring is used for realizing the radial sealing between the piston and the piston assembly guide hole; an inner sealing groove is formed on the inner wall of the valve core guide hole close to the bottom, an inner sealing ring is mounted in the inner sealing groove, and the inner sealing ring is used for realizing the radial sealing between the sealing seat and the valve core guide hole.

[0020] The outer sealing ring is selected from an O-shaped rubber sealing ring or a generic sealing ring which is composed of plastic and spring, and the inner sealing ring is selected from an O-shaped rubber sealing ring.

[0021] The valve body base at the bottom of the guiding hole of the piston assembly is coaxially provided with a sleeve mounting hole, the inner diameter of the sleeve mounting hole is larger than the inner diameter of the guiding hole of the piston assembly, the top of the sleeve mounting hole is communicated with the guiding hole of the piston assembly, and the bottom of the sleeve mounting hole is open; the valve body limiting boss can be limited on the inner end face between the sleeve mounting hole and the guiding hole of the piston assembly.

[0022] The sleeve mounting hole is mounted with a sleeve with open two ends, the bottom in the sleeve is mounted with a spring outer sleeve, the top of the spring outer sleeve is open and the bottom is closed, the bottom of the spring outer sleeve is mounted with the bottom of a main spring, the top of the main spring is sleeved with the bottom of a main spring seat, the top of the main spring seat is provided with a ball head, the bottom of the connecting seat of the auxiliary spring seat is provided with a ball socket, the ball head is matched with the ball socket to realize the pressure exertion of the main spring on the auxiliary spring seat.

[0023] The spring outer sleeve is further mounted with a locking nut for locking the spring outer sleeve and the sleeve.

[0024] The main spring seat is provided with a main spring seat boss, the piston assembly limiting ring is arranged at a position close to the top in the sleeve, the piston assembly limiting ring is located between the main spring seat boss and the mounting seat, the hole diameter of the through hole in the middle of the piston assembly limiting ring is smaller than the outer diameters of the main spring seat boss and the mounting seat and larger than the outer diameter of the connecting seat.

[0025] The mounting seat is mounted in the auxiliary spring seat mounting hole through thread cooperation, the sleeve is mounted in the sleeve mounting hole through thread cooperation, and the spring outer sleeve is mounted at the bottom in the sleeve through thread cooperation.

[0026] Compared with the prior art, the present application has the following technical effects:

[0027] (I) In the present application, the valve core adopts floating design, that is, the valve core can move axially in the piston, an axial gap H is arranged between the valve core and the auxiliary spring seat, and the auxiliary spring is compressed by 0.5 mm in the installed state, and the axial gap between the valve core and the auxiliary spring seat is (H-0.5) mm. In the long-term storage or non-pressurization condition of the engine system, the valve core sealing block is only subjected to the force of the auxiliary spring, and the sealing surface is always in a small stress state. When the system is pressurized, the valve core sealing block is subjected to the combined force of the auxiliary spring and the medium, so as to ensure the reliable sealing of the valve core and the valve seat. That is, in the non-working state, the sealing stress of the plastic sealing surface of the valve core is small, so as to be beneficial to prolonging the service life of the sealing surface and achieving the purpose of long service life. The present application simultaneously solves the problems that the stress is large in the long-term non-working state of the positive action type non-metallic sealing safety pressure relief device, the indentation of the non-metallic sealing surface is deep, and the opening and closing pressure deviates due to the change of the sealing surface form, and is more suitable for the environment of long-term storage.

[0028] (II) The pressure sensing structure (piston) and the valve core in the application are designed independently, the sealing of the valve core is not affected by the pressure sensing area, and better sealing can be realized. Meanwhile, the amplification effect of the pressure sensing area is fully utilized, and through reasonable optimization of the pressure sensing area and the main spring stiffness, a smaller opening and closing pressure difference can be realized.

[0029] (III) The valve core in the application adopts a structure of metal base and sealing block composite pressing, which reduces the mass of the valve core and avoids the failure of the whole non-metal valve core being stuck due to swelling in propellant. The total weight of the whole spring oscillator system is only 15 g, which greatly reduces the inertial force of the mechanical impact on the valve core, avoids damage to the sealing surface of the valve core and valve seat, and improves the service life. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a schematic view of the overall structure of the relief device in the installed state of the liquid rocket engine.

[0031] Figure 2 It is a schematic view of the structure of the valve body in the non-installed state.

[0032] Figure 3 It is a schematic view of the structure of the piston assembly.

[0033] Figure 4 It is a schematic view of the structure of the piston.

[0034] Figure 5 It is a schematic view of the structure of the valve core.

[0035] Figure 6 It is Figure 5 It is a schematic view of the structure of the valve core.

[0036] The meanings of the various reference numbers in the figure are as follows: 1 - valve body, 2 - piston assembly, 3 - sleeve, 4 - spring outer sleeve, 5 - main spring, 6 - main spring seat, 7 - ball head, 8 - locking nut, 9 - main spring seat boss, 10 - piston assembly limiting ring;

[0037] 101 - valve body base, 102 - piston assembly guide hole, 103 - valve body outlet, 104 - valve seat, 105 - valve body inlet, 106 - sleeve mounting hole;

[0038] 201 - piston, 202 - valve core, 203 - secondary spring seat, 204 - secondary spring, 205 - axial gap, 206 - outer sealing ring, 207 - inner sealing ring; 208 - valve core limiting boss, 209 - small stress state buffer gap;

[0039] 20101-lead pressure section, 20102-guide section, 20103-valve body limiting boss, 20104-valve core guide hole, 20105-lead pressure ring groove, 20106-lead pressure hole, 20107-sealing block guide hole, 20108-secondary spring seat mounting hole, 20109-outer sealing groove, 20110-inner sealing groove;

[0040] 20201-valve core base body, 20202-flat square channel, 20203-sealing block mounting hole, 20204-sealing block;

[0041] 20301-sealing seat, 20302-mounting seat, 20303-connection seat, 20304-secondary spring mounting hole, 20305-ball socket.

[0042] The specific content of the present application is further explained in detail in combination with the following embodiments. DETAILED DESCRIPTION

[0043] It should be noted that all components and devices in the present application, if not specifically stated, all adopt components and devices known in the prior art.

[0044] The following gives specific embodiments of the present application, it should be noted that the present application is not limited to the following specific embodiments, any equivalent transformation based on the technical solutions of the present application falls within the protection scope of the present application.

[0045] Embodiment:

[0046] The present embodiment gives a kind of safety pressure relief device for liquid rocket engine, as shown in Figure 1 and Figure 2 , including valve body 1 and piston assembly 2, valve body 1 includes valve body base body 101, piston assembly guide hole 102 is arranged in valve body base body 101, valve body outlet 103 is arranged on the top of piston assembly guide hole 102 of valve body base body 101, valve body outlet 103 is coaxially connected with piston assembly guide hole 102, and the end of valve body outlet 103 is provided with valve seat 104, and valve seat 104 is located in piston assembly guide hole 102;Valve body inlet 105 is also arranged on valve body base body 101 along the radial direction, and valve body inlet 105 is connected with the inner side wall close to the top of piston assembly guide hole 102.

[0047] As shown in Figure 3 and Figure 4As shown, the piston assembly 2 is installed in the piston assembly guide hole 102, and the piston assembly 2 comprises a piston 201 which is integrally formed from top to bottom into a pressure guiding section 20101, a guide section 20102 and a valve body limiting boss 20103, the outer diameter of the pressure guiding section 20101 is smaller than that of the guide section 20102, and the outer diameter of the guide section 20102 is smaller than that of the valve body limiting boss 20103; the pressure guiding section 20101 is installed in the piston assembly guide hole 102, and the cavity between the guide section 20102 and the inner wall of the piston assembly guide hole 102 is in communication with the valve body inlet 105; the guide section 20102 is fitted and installed in the piston assembly guide hole 102; and the valve body limiting boss 20103 can be limited by abutting against the end face of the bottom end of the piston assembly guide hole 102.

[0048] As shown in Figure 4 , Figure 5 and Figure 6 , the piston 201 is internally provided with a valve core guide hole 20104, and the valve core 202 is installed in the valve core guide hole 20104, the valve core 202 comprises a valve core base body 20201, two flat square channels 20202 are provided on the two axial sides of the valve core base body 20201, and the flat square channels 20202 form a medium flow channel with the valve core guide hole 20104.

[0049] The inner wall of the valve core guide hole 20104 close to the top is provided with a pressure guiding ring groove 20105, a plurality of pressure guiding holes 20106 which penetrate the pressure guiding section 20101 are radially provided in the pressure guiding ring groove 20105, and the pressure guiding holes 20106 are in communication with the valve body inlet 105 through the piston assembly guide hole 102 for medium flow.

[0050] The top of the pressure guiding section 20101 of the piston 201 is provided with a valve core limiting boss 208, a sealing block guide hole 20107 which penetrates the valve core limiting boss 208 is coaxially provided at the top of the valve core guide hole 20104, the inner diameter of the sealing block guide hole 20104 is smaller than that of the valve core guide hole 20104, a secondary spring seat installation hole 20108 which penetrates the bottom of the piston 201 is coaxially provided at the bottom of the valve core guide hole 20104, and the inner diameter of the secondary spring seat installation hole 20108 is larger than that of the valve core guide hole 20104.

[0051] The upper part of the valve core base body 20201 is provided with a sealing block installation hole 20203 which is open at the top, a sealing block 20204 is installed in the sealing block installation hole 20203, the top end of the sealing block 20204 is higher than the top end of the valve core base body 20201, and the sealing surface of the top end of the sealing block 20204 can contact and seal with the valve seat 104 through the sealing block guide hole 20107.

[0052] The secondary spring seat 203 is installed in the secondary spring seat mounting hole 20108, and the secondary spring seat 203 comprises a sealing seat 20301, a mounting seat 20302 and a connecting seat 20303 which are integrally formed from top to bottom, the outer diameter of the sealing seat 20301 is smaller than that of the mounting seat 20302, and the outer diameter of the mounting seat 20302 is larger than that of the connecting seat 20303; the sealing seat 20301 extends into the valve core guide hole 20104, the mounting seat 20302 is installed in the secondary spring seat mounting hole 20108, and the shaft shoulder between the mounting seat 20302 and the sealing seat 20301 can be limited on the inner end surface between the secondary spring seat mounting hole 20108 and the valve core guide hole 20104.

[0053] The upper part of the secondary spring seat 203 is provided with a top-opened secondary spring mounting hole 20304, and the secondary spring 204 is installed in the secondary spring mounting hole 20304.

[0054] As shown in Figure 1 the sealing block 20204 is in contact with the valve seat 104 in a sealing state, the secondary spring 204 is compressed by the valve core 202, so that there is a small stress state buffer gap 209 between the top end of the valve core base body 20201 and the lower surface of the valve core limiting boss 208.

[0055] As shown in Figure 3 the bottom end surface of the valve core base body 20201 and the top end surface of the sealing seat 20301 are provided with an axial gap 205.

[0056] In this embodiment, the valve body base body 101 is a rotary body structure along the central axis. The piston 201 is a hollow columnar structure. The sealing block 20204 is a cylindrical structure.

[0057] In this embodiment, the valve core 202 and the valve core guide hole 20104 are gap-fitted, and the fitting gap is 0.04mm-0.08mm; the piston assembly 2 and the piston assembly guide hole 102 are gap-fitted, and the fitting gap is 0.035mm-0.065mm.

[0058] In this embodiment, the piston 201 and the valve core 202 are designed independently, which fully utilizes the amplification effect of the piston to realize smaller opening and closing pressure difference and reliable sealing.

[0059] As a preferred scheme of this embodiment, the material of the sealing block 20204 is plastic or rubber.

[0060] As a preferred scheme of the embodiment, when the sealing specific pressure of the sealing block 20204 is less than or equal to 3 MPa, the sealing block 20204 is made of rubber material, and the sealing performance is good; when the sealing specific pressure of the sealing block 20204 is greater than 3 MPa, the sealing block 20204 is made of plastic material, so that the service life of the sealing pair is prolonged, and the stability is better.

[0061] As a preferred scheme of the embodiment, in a non-installed state in which the sealing surface of the sealing block 20204 does not contact and seal the valve seat 104, the spacing of the axial gap 205 is H; in an installed state in which the sealing surface of the sealing block 20204 contacts and extrudes the valve seat 104, the auxiliary spring 204 is compressed to a small stress state, and the spacing of the buffer gap 209 is 0.5 mm, so that the spacing of the axial gap 205 is H-0.5 mm. In the embodiment, further, H=1 mm is optimal.

[0062] As shown in Figure 1 , Figure 3 and Figure 4 , as a preferred scheme of the embodiment, an outer sealing groove 20109 is formed in the outer wall of the guide section 20102, and an outer sealing ring 206 is installed in the outer sealing groove 20109, the outer sealing ring 206 being used to realize radial sealing between the piston 201 and the piston assembly guide hole 102; an inner sealing groove 20110 is formed in the inner wall of the valve core guide hole 20104 close to the bottom, and an inner sealing ring 207 is installed in the inner sealing groove 20110, the inner sealing ring 207 being used to realize radial sealing between the sealing seat 20301 and the valve core guide hole 20104.

[0063] As a preferred scheme of the embodiment, the outer sealing ring 206 is selected to be an O-shaped rubber sealing ring or a generic sealing ring composed of plastic and a spring, and the inner sealing ring 207 is selected to be an O-shaped rubber sealing ring.

[0064] As shown in Figure 1 , as a preferred scheme of the embodiment, a sleeve installation hole 106 is coaxially formed in the valve body base body 101 at the bottom of the piston assembly guide hole 102, the inner diameter of the sleeve installation hole 106 being greater than the inner diameter of the piston assembly guide hole 102; the top of the sleeve installation hole 106 is in communication with the piston assembly guide hole 102, and the bottom of the sleeve installation hole 106 is open; the valve body limiting boss 20103 can be abutted on the inner end face between the sleeve installation hole 106 and the piston assembly guide hole 102 to be limited.

[0065] Further preferably, the sleeve mounting hole 106 is mounted with a sleeve 3 with open ends, a spring outer sleeve 4 is mounted at the bottom of the sleeve 3, the spring outer sleeve 4 has an open top end and a closed bottom end, a main spring 5 is mounted at the bottom of the spring outer sleeve 4, the top end of the main spring 5 is sleeved on the bottom of a main spring seat 6, the top of the main spring seat 6 is provided with a ball head 7, the bottom of a connecting seat 20303 of a secondary spring seat 203 is provided with a ball socket 20305, the ball head 7 is in contact with the ball socket 20305, and the main spring 5 is pressed against the secondary spring seat 203.

[0066] In the embodiment, the outer diameter of the ball head 7 is less than or equal to the inner diameter of the ball socket 20305, which is to reduce the friction between the ball head 7 and the ball socket 20305 during the adjustment of the opening pressure of the safety pressure relief device, and further reduce the force of the spring outer sleeve 4.

[0067] Further preferably, the spring outer sleeve 4 is further mounted with a locking nut 8 for locking the spring outer sleeve 4 and the sleeve 3.

[0068] Further preferably, the main spring seat 6 is provided with a main spring seat boss 9, the sleeve 3 is provided with a piston assembly limiting ring 10 at a position close to the top end, the piston assembly limiting ring 10 is located between the main spring seat boss 9 and the mounting seat 20302, the hole diameter of the through hole in the middle of the piston assembly limiting ring 10 is smaller than the outer diameters of the main spring seat boss 9 and the mounting seat 20302, and larger than the outer diameter of the connecting seat 20303.

[0069] Further preferably, the mounting seat 20302 is mounted in the secondary spring seat mounting hole 20108 through thread cooperation; the sleeve 3 is mounted in the sleeve mounting hole 106 through thread cooperation; and the spring outer sleeve 4 is mounted at the bottom of the sleeve 3 through thread cooperation.

[0070] In the embodiment, the sleeve 3 has a rotary body structure along the central axis, and the spring outer sleeve 4 has a rotary body structure along the central axis.

[0071] In use, the valve body 1, the sleeve 3 and the spring outer sleeve 4 are fixed through thread cooperation, the installation force of the main spring 5 is adjusted through the spring outer sleeve 4, the opening pressure of the safety pressure relief device is adjusted, the sleeve 3 and the spring outer sleeve 4 are locked and fixed through the locking nut 8, and the stability of the opening pressure of the safety pressure relief device after adjustment is ensured.

[0072] When the engine system is not supercharged, the valve core 202 of the safety relief device is only subjected to the force of the secondary spring 204, and the sealing surface of the sealing block 20204 is in a small stress state; when the engine system is supercharged, as the inlet pressure of the valve body inlet 105 gradually increases, the medium passes through the pressure guide hole 20106 on the piston 201, then passes through the flat square passage 20202 between the piston 201 and the valve core 202, and enters the axial gap 205 at the lower end of the valve core 202, at this time the valve core 202 is subjected to the combined action of the medium force and the spring force, and as the inlet pressure of the valve body inlet 105 increases, the sealing specific pressure on the sealing surface of the sealing block 20204 gradually increases, achieving a good sealing effect and realizing complete leakage of the medium.

[0073] When the inlet pressure of the valve body inlet 105 of the safety relief device continues to increase, the medium acting force acting on the piston assembly 2 can overcome the force of the main spring 5, the piston assembly 2 moves downward, and since the top end of the valve core base body 20201 and the lower surface of the valve core limiting boss 208 have a small stress state buffer gap 209 with a gap of 0.5 mm, the valve core 202 will not immediately move in the opening direction with the piston assembly 2.

[0074] As the inlet pressure of the valve body inlet 105 further increases, the piston assembly 2 moves downward and compresses the main spring 5 to 0.5 mm, and since the valve core 202 and the valve core guide hole 20104 are in a clearance fit, the valve core 202 can move relative to the piston 201, that is, the valve core 202 is always in close contact with the valve seat 104 under the action of the secondary spring 204, until the main spring 5 is compressed to 0.5 mm, the gap of the small stress state buffer gap 209 changes to 0 mm, and after the top end of the valve core base body 20201 contacts and limits the lower surface of the valve core limiting boss 208, the valve core 202 will move downward with the piston assembly 2, and the safety relief device is opened.

[0075] When the inlet pressure of the valve body inlet 105 of the safety relief device increases to a certain extent, the piston assembly 2 moves to the piston assembly limiting ring 10 arranged in the sleeve 3 to be limited, which can ensure the stability of the discharge state of the safety relief device after being opened, and avoids the vibration of the piston assembly 2 during the large flow discharge process.

[0076] When the engine system gradually recovers to normal pressure, the piston assembly 2 moves upward under the action of the main spring 5, and the top end of the valve core base body 20201 is always limited on the lower surface of the valve core limiting boss 208 before the sealing block 20204 of the valve core 202 contacts the valve seat 104, and moves upward together with the piston assembly 2, and the top end of the valve core base body 20201 gradually separates from the lower surface of the valve core limiting boss 208 after the sealing block 20204 of the valve core 202 contacts the valve seat 104 to form a seal, at this time the valve seat 104 limits the upward movement of the valve core 202, and the small stress state buffer gap 209 gradually increases in distance, and the piston assembly 2 continues to move upward until the valve body limiting boss 20103 is limited by the valve body 1, the distance of the small stress state buffer gap 209 returns to 0.5 mm, and the safety relief device is closed. The opening and closing pressure difference of the safety relief device is ΔP = P 开启 -P 关闭 = K / 2D 2 , wherein P 开启 is the opening pressure of the safety relief device, MPa; P 关闭 is the closing pressure of the safety relief device, MPa; K is the main spring stiffness, N / mm; and D is the diameter of the guide section (20102), mm. The size of the opening and closing pressure difference of the safety relief device determines the performance of the product, and the smaller the opening and closing pressure difference, the better the performance. As can be seen from the formula, the opening and closing pressure difference of the safety relief device can be optimized by reducing the main spring stiffness or increasing the diameter of the guide section, so that the performance is better.

[0077] That is, in the non-working state, the sealing block 20204 is only subjected to the force of the auxiliary spring 204, and the sealing surface of the sealing block 20204 is always in a small stress state, so that the sealing state of the sealing surface of the valve core remains unchanged after long-term storage of the safety relief device, thereby ensuring that the working characteristics of the safety relief device remain unchanged after long storage, that is, the opening and closing pressure and the sealing property remain unchanged, and at the same time, the small sealing stress is beneficial to prolonging the service life of the sealing surface, thereby achieving the purpose of long service life of the safety relief device.

[0078] The product of the present application has undergone multiple product production test examinations, and has undergone inspection tests, typical tests, single-machine mechanical environment tests, transportation vibration, random vibration, sinusoidal vibration, acceleration, low-frequency impact and high-frequency impact test examinations. After the mechanical environment test, the safety relief device is in good condition, the consistency of the retest values of the opening and closing pressure and the sealing property with the adjusted values before the mechanical environment is good, and meets the system design requirements. At present, the safety relief device has undergone multiple test examinations, and has been applied to multiple liquid rocket engine systems, and has the characteristics of small opening and closing pressure difference and high sealing reliability.

Claims

1. A relief device for a liquid rocket engine, comprising a valve body (1) and a piston assembly (2), characterized in that, The valve body (1) comprises a valve body base (101), a piston assembly guide hole (102) is arranged inside the valve body base (101), a valve body outlet (103) is arranged on the valve body base (101) at the top of the piston assembly guide hole (102), the valve body outlet (103) is coaxially connected with the piston assembly guide hole (102), a valve seat (104) is arranged at the end of the valve body outlet (103), and the valve seat (104) is located in the piston assembly guide hole (102); a valve body inlet (105) is also arranged on the valve body base (101) along the radial direction, and the valve body inlet (105) is connected with the inner side wall of the piston assembly guide hole (102) close to the top; The piston assembly guide hole (102) is provided with a piston assembly (2), the piston assembly (2) comprises a piston (201), the piston (201) is integrally formed from top to bottom into a pressure guiding section (20101), a guide section (20102) and a valve body limiting boss (20103), the outer diameter of the pressure guiding section (20101) is smaller than that of the guide section (20102), and the outer diameter of the guide section (20102) is smaller than that of the valve body limiting boss (20103); the pressure guiding section (20101) is arranged in the piston assembly guide hole (102), and the cavity between the pressure guiding section (20101) and the inner wall of the piston assembly guide hole (102) is connected with the valve body inlet (105); the guide section (20102) is arranged in the piston assembly guide hole (102) in a matched mode; and the valve body limiting boss (20103) can be limited by being abutted against the end face at the bottom end of the piston assembly guide hole (102); The piston (201) is internally provided with a valve core guide hole (20104), a valve core (202) is arranged in the valve core guide hole (20104), the valve core (202) comprises a valve core base (20201), two flat square channels (20202) are arranged on the two sides of the valve core base (20201) in the axial direction, and the flat square channels (20202) form a medium flow channel together with the valve core guide hole (20104); A pressure guiding ring groove (20105) is arranged on the inner wall of the valve core guide hole (20104) close to the top, a plurality of pressure guiding holes (20106) penetrating through the pressure guiding section (20101) are arranged in the pressure guiding ring groove (20105) along the radial direction, and the pressure guiding holes (20106) are connected with the valve body inlet (105) through the piston assembly guide hole (102) to flow the medium. The top of the pressure introduction section (20101) of the piston (201) is provided with a valve core limiting boss (208), the top of the valve core guide hole (20104) is coaxially provided with a sealing block guide hole (20107) penetrating the valve core limiting boss (208), the inner diameter of the sealing block guide hole (20107) is smaller than the inner diameter of the valve core guide hole (20104), the bottom of the valve core guide hole (20104) is coaxially provided with a secondary spring seat mounting hole (20108) penetrating the bottom of the piston (201), and the inner diameter of the secondary spring seat mounting hole (20108) is larger than the inner diameter of the valve core guide hole (20104); The upper part of the valve core base body (20201) is provided with a top-open sealing block mounting hole (20203), the sealing block mounting hole (20203) is mounted with a sealing block (20204), the top end of the sealing block (20204) is higher than the top end of the valve core base body (20201), and the sealing surface of the top end of the sealing block (20204) can contact and seal with the valve seat (104) through the sealing block guide hole (20107); The secondary spring seat mounting hole (20108) is mounted with a secondary spring seat (203), the secondary spring seat (203) comprises a sealing seat (20301), a mounting seat (20302) and a connecting seat (20303) which are integrally formed from top to bottom, the outer diameter of the sealing seat (20301) is smaller than the outer diameter of the mounting seat (20302), the outer diameter of the mounting seat (20302) is larger than the outer diameter of the connecting seat (20303), the sealing seat (20301) is fitted and mounted in the valve core guide hole (20104), the mounting seat (20302) is fitted and mounted in the secondary spring seat mounting hole (20108), and the shaft shoulder between the mounting seat (20302) and the sealing seat (20301) can be limited on the inner end surface between the secondary spring seat mounting hole (20108) and the valve core guide hole (20104); The upper part of the secondary spring seat (203) is provided with a top-open secondary spring mounting hole (20304), and a secondary spring (204) is mounted in the secondary spring mounting hole (20304); In the state that the sealing block (20204) contacts and seals with the valve seat (104), the secondary spring (204) is compressed by the valve core (202), so that the top end of the valve core base body (20201) and the lower surface of the valve core limiting boss (208) have a small stress state buffer gap (209); The bottom end surface of the valve core base body (20201) and the top end surface of the sealing seat (20301) are provided with an axial gap (205).

2. The relief device for a liquid rocket engine according to claim 1, wherein When the sealing specific pressure of the sealing block (20204) is ≤3MPa, the sealing block (20204) is made of rubber material; when the sealing specific pressure of the sealing block (20204) is >3MPa, the sealing block (20204) is made of plastic material.

3. The relief device for a liquid rocket engine as recited in claim 1, wherein In the non-installed state where the sealing surface of the sealing block (20204) is not in contact with the valve seat (104) for sealing, the axial gap (205) has a distance H; in the installed state where the sealing surface of the sealing block (20204) is in contact with the valve seat (104) for sealing, the auxiliary spring (204) is compressed to a small stress state to buffer the distance of the gap (209) of 0.5 mm, and the axial gap (205) has a distance of H-0.5 mm.

4. The pressure relief device for a liquid rocket engine according to claim 1, wherein An outer sealing groove (20109) is formed in the outer wall of the guiding section (20102), and an outer sealing ring (206) is installed in the outer sealing groove (20109), and the outer sealing ring (206) is used to realize radial sealing between the piston (201) and the piston assembly guiding hole (102); an inner sealing groove (20110) is formed in the inner wall of the valve core guiding hole (20104) close to the bottom, and an inner sealing ring (207) is installed in the inner sealing groove (20110), and the inner sealing ring (207) is used to realize radial sealing between the sealing seat (20301) and the valve core guiding hole (20104).

5. The relief device for a liquid rocket engine as recited in claim 4, wherein The outer sealing ring (206) is an O-shaped rubber sealing ring or a generic sealing ring composed of plastic and a spring, and the inner sealing ring (207) is an O-shaped rubber sealing ring.

6. The pressure relief device for a liquid rocket engine as recited in claim 1, wherein A sleeve installation hole (106) is coaxially formed in the valve body base body (101) at the bottom of the piston assembly guiding hole (102), and the inner diameter of the sleeve installation hole (106) is greater than the inner diameter of the piston assembly guiding hole (102); the top of the sleeve installation hole (106) is in communication with the piston assembly guiding hole (102), and the bottom of the sleeve installation hole (106) is open; and the valve body limiting boss (20103) can be positioned on the inner end face between the sleeve installation hole (106) and the piston assembly guiding hole (102).

7. The relief device for a liquid rocket engine as recited in claim 6, wherein A sleeve (3) with open two ends is installed in the sleeve installation hole (106), a spring outer sleeve (4) is installed at the bottom in the sleeve (3), the top of the spring outer sleeve (4) is open and the bottom is closed, the bottom end of the spring outer sleeve (4) is installed in the main spring (5), the top of the main spring (5) is on the bottom of the main spring seat (6), the top of the main spring seat (6) is provided with a ball head (7), the bottom of the connecting seat (20303) of the auxiliary spring seat (203) is provided with a ball socket (20305), the ball head (7) is in contact with the ball socket (20305), and the main spring (5) is pressed against the piston assembly (2).

8. The pressure relief device for a liquid rocket engine as recited in claim 7, wherein A locking nut (8) is further installed on the spring outer sleeve (4) to lock the spring outer sleeve (4) and the sleeve (3).

9. The pressure relief device for a liquid rocket engine as recited in claim 7, wherein A main spring seat boss (9) is arranged on the main spring seat (6), a piston assembly limiting ring (10) is arranged at a position close to the top in the sleeve (3), the piston assembly limiting ring (10) is located between the main spring seat boss (9) and the valve body limiting boss (20103), the hole diameter of the through hole in the middle of the piston assembly limiting ring (10) is smaller than the outer diameters of the main spring seat boss (9) and the valve body limiting boss (20103), and is greater than the outer diameter of the connecting seat (20303).

10. The pressure relief device for a liquid rocket engine of claim 7, wherein The mounting seat (20302) is installed in the auxiliary spring seat mounting hole (20108) through screw fit; the sleeve (3) is installed in the sleeve mounting hole (106) through screw fit; the bottom of the sleeve (3) is installed with the spring outer sleeve (4) through screw fit.

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