A two-stage supercharging cryogenic liquid booster pump

Abstract

This invention relates to the field of cryogenic liquid pressurization technology, and more particularly to a two-stage cryogenic liquid pressurization pump. The pressurization pump includes: a Dewar flask, internally forming a first chamber for containing cryogenic liquid; a fixed assembly, a flange fixed to the Dewar flask; and a compound piston assembly that moves vertically relative to the fixed assembly. The compound piston assembly and the fixed assembly form a pre-pressurization chamber and a high-pressure chamber. The pre-pressurization chamber is located below the high-pressure chamber and is connected to the first chamber via an inlet channel, pressurizing the cryogenic liquid to an intermediate pressure and discharging it into the high-pressure chamber. The high-pressure chamber then pressurizes the cryogenic liquid to a target high pressure and discharges it to a downstream high-pressure pipeline via a drain channel. An inlet valve is provided in the inlet channel, a drain valve is provided in the drain channel, and an intermediate valve is provided between the pre-pressurization chamber and the high-pressure chamber. By placing the pre-pressurization chamber below the high-pressure chamber, the height of the inlet is reduced, thus reducing the mixing of impurities, increasing the subcooling of the cryogenic liquid, and improving the quality of the incoming liquid.

Description

Technical Field

[0001] This invention relates to the field of cryogenic liquid boosting technology, and more particularly to a two-stage boosting cryogenic liquid booster pump. Background Technology

[0002] In aerospace, energy, and other fields, the efficient transport and pressurization of cryogenic liquids such as liquid hydrogen, liquid helium, and liquid nitrogen are core technological requirements. Cryogenic liquid booster pumps, as key equipment, directly determine the stability and reliability of the system. To prevent vaporization of the cryogenic medium due to a sudden pressure increase during pressurization, existing technologies generally employ a two-stage pressurization mode: first, the cryogenic medium is pressurized to an intermediate pressure to provide sufficient subcooling, and then further pressurized to the target high pressure.

[0003] In related technologies, the pre-compression chamber of the booster pump is located above the high-pressure chamber, and the liquid inlet is located at the top of the pre-compression chamber. This makes the liquid inlet position relatively high, so when the low-temperature liquid enters the pre-compression chamber, it is easy to entrain air or gaseous impurities, which leads to a decrease in the quality of the liquid entering the chamber, insufficient subcooling, and thus easily induces the risk of vaporization, affecting the stability of the booster.

[0004] Therefore, there is an urgent need to provide a two-stage pressurized cryogenic liquid booster pump to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides a two-stage pressurized cryogenic liquid booster pump, which can reduce the mixing of impurities, increase the subcooling of the cryogenic liquid, and improve the quality of the influent.

[0006] This invention provides a two-stage pressurized cryogenic liquid booster pump, comprising: The Dewar has an internal cavity formed to contain the cryogenic liquid; The fixing component is fixed to the flange on the upper part of the Dewar; The composite piston assembly moves up and down relative to the fixed assembly. The composite piston assembly and the fixed assembly form a pre-compression chamber and a high-pressure chamber. The pre-compression chamber is located below the high-pressure chamber and is connected to the first chamber through an inlet channel. The pre-compression chamber is used to pressurize the cryogenic liquid to an intermediate pressure and discharge it into the high-pressure chamber. The high-pressure chamber is connected to the downstream high-pressure pipeline outside the Dewar through a drain channel. The high-pressure chamber is used to pressurize the cryogenic liquid to the target high pressure. An inlet valve is provided in the inlet channel, a drain valve is provided in the drain channel, and an intermediate valve is provided between the pre-compression chamber and the high-pressure chamber.

[0007] Compared with related technologies, the present invention has at least the following beneficial effects: The two-stage pressurized cryogenic liquid booster pump provided by the present invention, by setting the pre-compression chamber below the high-pressure chamber and the liquid inlet located at the bottom of the pre-compression chamber, allows the cryogenic liquid to enter the pre-compression chamber from the lowest position. The pre-compression chamber pressurizes the cryogenic liquid to an intermediate pressure and discharges it into the high-pressure chamber, which significantly reduces the possibility of gas mixing in the liquid inlet path. At the same time, it allows the cryogenic liquid to obtain a more sufficient pre-cooling environment before entering, thereby effectively improving the liquid subcooling. This solves the problems of the traditional structure, which has an excessively high liquid inlet position, is prone to bubble entrapment, and has insufficient subcooling due to the pre-compression chamber being located above the high-pressure chamber. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram of the structure of a two-stage pressurized cryogenic liquid booster pump provided in an embodiment of the present invention.

[0010] Figure label: 1-Duwa; 11-First cavity; 12-Flange 2-Fixed components; 22-Shell; 23-First cylinder block; 231-Drainage channel; 232 - Drain valve; 24 - Second cylinder block; 241 - Intermediate valve; 25- Bolt; 3-Composite piston assembly; 31-High-pressure piston; 311 - High-pressure chamber; 32 - Low-pressure piston; 321 - Pre-compression chamber; 322 - Inlet flow channel; 323 - Inlet valve; 324 - Second through hole; 325 - Overflow channel; 326 - Overflow valve; 33-Disc; 34-Cylinder; 341 - Second cavity. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] like Figure 1 As shown, an embodiment of the present invention provides a two-stage pressurized cryogenic liquid booster pump, comprising: Dewar 1, with an internal first cavity 11 for containing cryogenic liquid; Fixing component 2, fixed to flange 12 on the upper part of Dewar 1; The composite piston assembly 3 moves up and down relative to the fixed assembly 2. The composite piston assembly 3 and the fixed assembly 2 form a pre-compression chamber 321 and a high-pressure chamber 311. The pre-compression chamber 321 is located below the high-pressure chamber 311. The pre-compression chamber 321 is connected to the first chamber 11 through the liquid inlet channel 322. The pre-compression chamber 321 is used to pressurize the cryogenic liquid to an intermediate pressure and discharge it into the high-pressure chamber 311. The high-pressure chamber 311 is connected to the downstream high-pressure pipeline (not shown in the figure) outside the Dewar 1 through the liquid outlet channel 231. The high-pressure chamber is used to pressurize the cryogenic liquid to the target high pressure. The liquid inlet channel 322 is provided with a liquid inlet valve 323, and the liquid outlet channel 231 is provided with a liquid outlet valve 232. An intermediate valve 241 is provided between the pre-compression chamber 321 and the high-pressure chamber 311.

[0013] In this embodiment, by setting the pre-compression chamber 321 below the high-pressure chamber 311 and the liquid inlet located at the bottom of the pre-compression chamber 321, the cryogenic liquid enters the pre-compression chamber 321 from the lowest position. The pre-compression chamber 321 is used to pressurize the cryogenic liquid to an intermediate pressure and discharge it into the high-pressure chamber 311 to provide sufficient subcooling. This significantly reduces the possibility of gas mixing in the liquid inlet path and allows the cryogenic liquid to obtain a more adequate pre-cooling environment before entering, thereby effectively improving the liquid subcooling. This solves the problems of the traditional structure, where the liquid inlet position is too high, air bubbles are easily entangled, and the subcooling is insufficient due to the pre-compression chamber being located above the high-pressure chamber.

[0014] It should be noted that the inlet valve 323 is located at the inlet of the pre-compression chamber 321 and is used to control the unidirectional inlet of the cryogenic liquid from the first chamber 11 into the pre-compression chamber 321; the intermediate valve 241 is located in the channel between the pre-compression chamber 321 and the high-pressure chamber 311 and is used to control the unidirectional flow of the cryogenic liquid from the pre-compression chamber 321 to the high-pressure chamber 311 when the composite piston assembly 3 moves upward; the drain valve 232 is located at the drain outlet of the high-pressure chamber 311 and is used to control the unidirectional discharge of the high-pressure liquid.

[0015] In one embodiment of the present invention, the cryogenic liquid includes at least one of liquid hydrogen, liquid helium, and liquid nitrogen, and the specific type of cryogenic liquid is not limited herein.

[0016] In one embodiment of the present invention, the low-pressure piston 32 is further provided with an overflow channel 325 and an overflow valve 326, with the overflow valve 326 disposed in the overflow channel 325.

[0017] In this embodiment, the overflow valve 326, the inlet valve 323, and the intermediate valve 241 are connected in parallel to form a pressure control loop. When the composite piston assembly 3 moves downward, increasing the volume of the pre-pressure chamber 321, the inlet valve 323 opens to allow the cryogenic liquid to enter. When the composite piston assembly 3 moves upward, causing the liquid in the pre-pressure chamber 321 to be compressed and the pressure to rise above a set threshold, the overflow valve 326 automatically opens, allowing some liquid to leak out from the outlet side of the pre-pressure chamber 321. This effectively suppresses abnormal pressure fluctuations in the pre-pressure chamber 321 caused by a larger volume change than the high-pressure chamber 311, achieving dynamic stability of the pressure in the pre-pressure chamber 321. At the same time, since the overflow valve 326, the inlet valve 323, and the intermediate valve 241 are connected in parallel, the three work together to ensure unidirectional flow of liquid in normal pressurization cycles and provide redundant pressure relief channels under overpressure conditions. This avoids system impact or sealing failure caused by liquid accumulation, significantly improving the reliability and safety of the pressurization process.

[0018] In one embodiment of the present invention, the fixing component 2 includes a housing 22 fixed inside the flange 12 and a first cylinder 23 and a second cylinder 24 fixedly connected to the housing 22. The top end of the housing 22 is located outside the Dewar 1 and the bottom end is located inside the Dewar 1. The first cylinder 23 and the second cylinder 24 are both located inside the Dewar 1. The composite piston assembly 3 moves up and down relative to the housing 22, the first cylinder 23, and the second cylinder 24.

[0019] In this embodiment, by setting up the housing 22, the first cylinder 23 and the second cylinder 24, the composite piston assembly 3 can move up and down inside the Dewar 1, thereby completing the two-stage pressurization of the cryogenic liquid.

[0020] In one embodiment of the present invention, the composite piston assembly 3 includes a high-pressure piston 31 and a low-pressure piston 32. The high-pressure piston 31 is located above the low-pressure piston 32. The high-pressure piston 31 moves up and down relative to the housing 22 and the first cylinder 23. The low-pressure piston 32 moves up and down relative to the second cylinder 24. A high-pressure chamber 311 is formed between the high-pressure piston 31, the first cylinder 23 and the second cylinder 24. A pre-pressure chamber 321 is formed between the low-pressure piston 32 and the second cylinder 24. An inlet valve 323 and an inlet channel 322 are disposed in the low-pressure piston 32. A drain valve 232 and a portion of the drain channel 231 are disposed in the first cylinder 23. An intermediate valve 241 is disposed in the second cylinder 24.

[0021] In this embodiment, by setting the intermediate valve 241 inside the second cylinder 24, the pre-compression chamber 321, the intermediate valve 241, and the high-pressure chamber 311 form a direct connection structure (i.e., there is no other connection structure with bent flow channels). Compared with the traditional two-stage booster structure, the pre-compression chamber and the intermediate flow channel are optimized, reducing the volume and clearance of the intermediate flow channel from the pre-compression chamber to the high-pressure chamber, achieving precise matching of the volumes of the pre-compression chamber and the high-pressure chamber, and improving booster efficiency.

[0022] In one embodiment of the present invention, the composite piston assembly 3 further includes a disc 33 and a cylinder 34. The high-pressure piston 31, the disc 33, the cylinder 34 and the low-pressure piston 32 are connected in sequence. The housing 22 and the first cylinder 23 are connected by bolts 25. The disc 33 is provided with a first through hole for the bolt 25 to pass through, so that the disc 33 can move up and down relative to the bolt 25. The cylinder 34 is located outside the first cylinder 23 and the second cylinder 24 and forms a second cavity 341. The bottom of the low-pressure piston 32 is provided with a second through hole 324, which communicates with the second cavity 341 and the first cavity 11 respectively.

[0023] In this embodiment, by setting up a disc 33 and a cylinder 34, and setting a second through hole 324 at the bottom of the low-pressure piston 32, a second cavity 341 is formed outside the first cylinder 23 and the second cylinder 24. In this way, the cryogenic liquid in the first cavity 11 can enter the second cavity 341 through the second through hole 324 to exchange heat with the outer wall surfaces of the first cylinder 23 and the second cylinder 24, thereby achieving passive circulating heat exchange. This breaks the original liquid static state of the closed cavity, enhances the heat exchange effect of the outer wall surface of the cylinder, and avoids the risk of temperature rise or vaporization of the cryogenic liquid.

[0024] In one embodiment of the present invention, the disc 33 and the high-pressure piston 31 are detachably connected by screws, and the cylinder 34 is detachably connected to the disc 33 and the low-pressure piston 32 by screws.

[0025] In this embodiment, the high-pressure piston 31, disc 33, cylinder 34 and low-pressure piston 32 abandon the integral welding or non-removable connection method, and instead adopt a screw-based detachable rigid connection structure, so that the high-pressure piston, disc, cylinder and low-pressure piston form a modular combination, allowing any worn part to be replaced without disassembling the Dewar.

[0026] In one embodiment of the present invention, the high-pressure piston 31 has a support ring groove and multiple piston ring grooves on its side. The support ring groove is used to install a support ring to provide stable axial support and prevent the high-pressure piston from shifting or deforming under high-pressure conditions. The multiple piston ring grooves cooperate with the high-pressure chamber cylinder liner to form a multi-stage sealing structure, effectively blocking the axial leakage path of the cryogenic liquid in the high-pressure chamber. The low-pressure piston 32 also has a piston ring groove on its side. The piston ring groove is tightly fitted with the inner wall of the pre-pressure chamber to form a single-stage sealing interface, so that the low-pressure piston can completely isolate the liquid flow between the pre-pressure chamber and the outside or transmission area during the reciprocating motion, preventing the cryogenic liquid from internal leakage or vaporization loss in the low-pressure stage.

[0027] In one embodiment of the present invention, the high-pressure piston 31 and the disk 33 are coaxially aligned through a stop structure. The stop structure is located on the mating surface between the lower end of the high-pressure piston and the upper end of the disk to ensure that the two maintain strict coaxiality during reciprocating motion. The cylinder 34 and the low-pressure piston 32 are coaxially aligned through a stop structure. The stop structure is located on the mating surface between the upper end of the cylinder and the upper end of the low-pressure piston to ensure that the low-pressure piston reciprocates stably along the axis in the pre-compression chamber, effectively preventing liquid leakage, increased frictional resistance, or piston instability caused by eccentricity.

[0028] In one embodiment of the present invention, the diameters of the pre-compression chamber 321 and the high-pressure chamber 311 satisfy the following formula: d2>1.1×d4 In the formula, d2 is the diameter of the pre-compression chamber 321, and d4 is the diameter of the high-pressure chamber 311; The diameters of the low-pressure piston 32 and the pre-compression chamber 321 satisfy the following formula: d2=d1+2z In the formula, d1 is the diameter of the low-pressure piston 32, and z is the minimum clearance between the piston wall and its mating surface. The diameter of the high-pressure piston 31 and the inner diameters of the first cylinder 23 and the second cylinder 24 satisfy the following formula: d6 = d5 - 2i = d3 + 2z In the formula, d6 is the inner diameter of the second cylinder 24, d5 is the inner diameter of the first cylinder 23, i is the thickness of the cylinder liner of the high-pressure chamber 311, and d3 is the diameter of the high-pressure piston 31.

[0029] In this implementation, the geometric relationship d2 > 1.1 × d4 is satisfied, ensuring that the volume increase of the pre-compression chamber when the low-pressure piston moves downward significantly exceeds the liquid volume required for the high-pressure chamber to be drawn in when the high-pressure piston moves upward. This ensures that the pre-compression chamber can fully draw in and store sufficient cryogenic liquid in each working cycle, overcoming the problem of insufficient liquid intake caused by volume ratio imbalance. The geometric relationships d6 = d5 - 2i = d3 + 2z and d2 = d1 + 2z are satisfied, ensuring that a uniform and controllable minimum clearance z is always maintained between the high-pressure piston and the high-pressure chamber cylinder liner. This avoids friction and wear due to excessive tightness or liquid leakage and sealing failure due to excessive clearance. It also keeps the radial clearance between the low-pressure piston and the second cylinder stable, ensuring the smoothness of its axial movement and the reliable fit of the seals.

[0030] In one embodiment of the present invention, the stroke of the composite piston assembly 3 satisfies the following formula: ab-2y>s s-e+r1<fy s-g+r2<hy s-g+r2<j l=j+k+d+g s-e+r1<m n=e+o+m In the formula, s is the stroke of the compound piston assembly 3, a is the distance between the housing 22 and the first cylinder 23, b is the thickness of the disk 33, y is the minimum distance between the disk 33 and the housing 22 and the first cylinder 23 during the movement of the compound piston assembly 3, e is the distance between the top of the low-pressure piston 32 and the top dead center of the pre-pressure chamber 321 during the upward movement of the compound piston assembly 3, r1 is the fillet radius at the top dead center of the pre-pressure chamber 321, f is the distance between the disk 33 and the housing 22 at the same moment, g is the distance between the bottom of the high-pressure piston 31 and the bottom dead center of the high-pressure chamber 311 during the downward movement of the compound piston assembly 3, and r2 is the position of the bottom dead center of the high-pressure chamber 311. The radius of the corner is rounded, h is the distance between the disk 33 and the first cylinder 23 at the same moment, j is the minimum distance between the support ring of the high-pressure piston 31 and the top of the first cylinder 23 during the upward movement of the composite piston assembly 3, k is the total width of the piston ring and support ring of the high-pressure piston 31, d is the depth of the upper circular hole of the second cylinder 24, l is the distance between the bottom dead center of the high-pressure chamber 311 and the top of the first cylinder 23, m is the minimum distance between the piston ring of the low-pressure piston 32 and the bottom of the second cylinder 24 during the downward movement of the composite piston assembly 3, n is the depth of the lower circular hole of the second cylinder 24, and o is the maximum distance from the sealing groove of the low-pressure piston 32 to the top of the low-pressure piston 32.

[0031] In this embodiment, satisfying the geometric relationship ab-2y>s ensures that the disc retains sufficient movement margin when the piston is at its maximum stroke position, preventing hard contact with the housing 22 or the first cylinder 23 when it reaches its limit position, thus ensuring the smoothness of the transmission system. Satisfying the geometric relationships s-e+r1<fy and s-g+r2<hy ensures that the piston ring of the low-pressure piston is always located within the mating area between the end face of the pre-compression chamber and the piston ring groove when the low-pressure piston is at its upper and lower limit positions, preventing the piston ring from detaching from the support surface and losing its sealing function due to excessive stroke or miscalculation of structural clearance. Satisfying the geometric relationships s-g+r2<j and l=j+k+d+g ensures that the support ring is always constrained within the designed ring groove space during the reciprocating motion of the piston, avoiding displacement or detachment due to excessive axial displacement. Satisfying the geometric relationships s-e+r1<m and n=e+o+m further limits the minimum safety margin of the low-pressure piston ring in axial movement, ensuring that it can maintain stable contact under high pressure differential environment, improving sealing reliability and system durability. Therefore, the synergistic constraint of the above structural parameters effectively solves the problems of sealing failure, component dislocation and mechanical interference caused by uncontrolled structural clearance in high-frequency reciprocating motion of the composite piston.

[0032] The process of the technical solution in this application is described below: The composite piston assembly 3 reciprocates up and down within the Dewar 1. Cryogenic liquid enters the pre-compression chamber 321 through the inlet at the bottom of the pre-compression chamber 321 via the inlet valve 323. The pre-compression chamber 321 is located within the lower circular hole of the second cylinder 24, and its inlet corresponds to the bottom dead center of the low-pressure piston 32. When the composite piston assembly 3 moves downwards, the volume of the pre-compression chamber 321 increases, the pressure decreases, and the inlet valve 323 opens, allowing the cryogenic liquid to flow into the pre-compression chamber 321. Simultaneously, the high-pressure chamber 31... When the volume of the pre-compression chamber 321 decreases and the pressure increases, the drain valve 232 opens, and the high-pressure liquid is discharged through the drain valve 232 to the drain channel 231, while the intermediate valve 241 remains closed. When the composite piston assembly 3 moves upward, the inlet valve 323 and the drain valve 232 close, the volume of the pre-compression chamber 321 decreases, and the pressure increases. The intermediate valve 241 opens, and the cryogenic liquid flows unidirectionally from the pre-compression chamber 321 into the high-pressure chamber 311 through the intermediate valve 241. Simultaneously, the volume of the high-pressure chamber 311 increases, and the pressure decreases. Since the volume of the pre-compression chamber 321 is larger than that of the high-pressure chamber 311, the overflow valve 326 is used to discharge excess liquid and control the liquid pressure in the pre-compression chamber 321.

[0033] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0034] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A two-stage pressurized cryogenic liquid booster pump, characterized in that, include: The Dewar has an internal cavity formed to contain the cryogenic liquid; The fixing component is fixed to the flange on the upper part of the Dewar; The composite piston assembly moves up and down relative to the fixed assembly. The composite piston assembly and the fixed assembly form a pre-compression chamber and a high-pressure chamber. The pre-compression chamber is located below the high-pressure chamber and is connected to the first chamber through an inlet channel. The pre-compression chamber is used to pressurize the cryogenic liquid to an intermediate pressure and discharge it into the high-pressure chamber. The high-pressure chamber is connected to the downstream high-pressure pipeline outside the Dewar through a drain channel. The high-pressure chamber is used to pressurize the cryogenic liquid to the target high pressure. An inlet valve is provided in the inlet channel, a drain valve is provided in the drain channel, and an intermediate valve is provided between the pre-compression chamber and the high-pressure chamber.

2. The cryogenic liquid booster pump according to claim 1, characterized in that, The fixing assembly includes a housing fixed inside the flange and a first cylinder and a second cylinder fixedly connected to the housing. The top end of the housing is located outside the Dewar and the bottom end is located inside the Dewar. Both the first cylinder and the second cylinder are located inside the Dewar. The composite piston assembly moves up and down relative to the housing, the first cylinder, and the second cylinder.

3. The cryogenic liquid booster pump according to claim 2, characterized in that, The composite piston assembly includes a high-pressure piston and a low-pressure piston. The high-pressure piston is located above the low-pressure piston. The high-pressure piston moves up and down relative to the housing and the first cylinder, while the low-pressure piston moves up and down relative to the second cylinder. A high-pressure chamber is formed between the high-pressure piston, the first cylinder, and the second cylinder, and a pre-compression chamber is formed between the low-pressure piston and the second cylinder. An inlet valve and an inlet channel are located inside the low-pressure piston, a drain valve and part of the drain channel are located inside the first cylinder, and an intermediate valve is located inside the second cylinder.

4. The cryogenic liquid booster pump according to claim 3, characterized in that, The composite piston assembly also includes a disc and a cylinder. The high-pressure piston, disc, cylinder and low-pressure piston are connected in sequence. The housing and the first cylinder are connected by bolts. The disc is provided with a first through hole for the bolt to pass through, so that the disc can move up and down relative to the bolt. The cylinder is located outside the first cylinder and the second cylinder and forms a second cavity. The bottom of the low-pressure piston is provided with a second through hole, which communicates with the second cavity and the first cavity respectively.

5. The cryogenic liquid booster pump according to claim 4, characterized in that, The disc and the high-pressure piston are detachably connected by screws, and the cylinder is detachably connected to the disc and the low-pressure piston by screws respectively.

6. The cryogenic liquid booster pump according to claim 3, characterized in that, The low-pressure piston is also equipped with an overflow channel and an overflow valve, with the overflow valve located in the overflow channel.

7. The cryogenic liquid booster pump according to claim 1, characterized in that, Cryogenic liquids include at least one of liquid hydrogen, liquid helium, and liquid nitrogen.

8. The cryogenic liquid booster pump according to any one of claims 3-7, characterized in that, The diameters of the pre-compression chamber and the high-pressure chamber satisfy the following formula: d2>1.1×d4 In the formula, d2 is the diameter of the pre-compression chamber and d4 is the diameter of the high-pressure chamber; The diameters of the low-pressure piston and the pre-compression chamber satisfy the following formula: d2=d1+2z In the formula, d1 is the diameter of the low-pressure piston, and z is the minimum clearance between the piston wall and its mating surface. The diameter of the high-pressure piston and the inner diameters of the first and second cylinders satisfy the following formula: d6 = d5 - 2i = d3 + 2z In the formula, d6 is the inner diameter of the second cylinder, d5 is the inner diameter of the first cylinder, i is the thickness of the high-pressure chamber cylinder liner, and d3 is the diameter of the high-pressure piston.

9. The cryogenic liquid booster pump according to any one of claims 4-7, characterized in that, The stroke of the compound piston assembly satisfies the following formula: ab-2y>s s-e+r1<fy s-g+r2<hy s-g+r2<j l=j+k+d+g s-e+r1<m n=e+o+m In the formula, s is the stroke of the compound piston assembly, a is the distance between the housing and the first cylinder, b is the thickness of the disk, y is the minimum distance between the disk and the housing and the first cylinder during the movement of the compound piston assembly, e is the distance between the top of the low-pressure piston and the top dead center of the pre-pressure chamber during the upward movement of the compound piston assembly, r1 is the fillet radius at the top dead center of the pre-pressure chamber, f is the distance between the disk and the housing at the same moment, g is the distance between the bottom of the high-pressure piston and the bottom dead center of the high-pressure chamber during the downward movement of the compound piston assembly, and r2 is the fillet radius at the bottom dead center of the high-pressure chamber. h is the distance between the disk and the first cylinder at the same moment; j is the minimum distance between the support ring of the high-pressure piston and the top of the first cylinder during the upward movement of the compound piston assembly; k is the total width of the piston ring and support ring of the high-pressure piston; d is the depth of the circular hole on the second cylinder; l is the distance between the bottom dead center of the high-pressure chamber and the top of the first cylinder; m is the minimum distance between the piston ring of the low-pressure piston and the bottom of the second cylinder during the downward movement of the compound piston assembly; n is the depth of the circular hole on the lower part of the second cylinder; and o is the maximum distance from the sealing groove of the low-pressure piston to the top of the low-pressure piston.

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