Manual nitrogen pumping pressure reducer

Abstract

The invention discloses a manual nitrogen pumping pressure reducer which comprises a gas inlet pipeline, a valve body fixed in the radial direction of the gas inlet pipeline, a propelling threaded rod arranged in the valve body, a valve needle connected with the propelling threaded rod and extending into the gas inlet pipeline, a handle driving the propelling threaded rod to rotate, and an expansion cavity arranged in a throttling area, matched with the valve needle, of the inner wall of the gas inlet pipeline. And a revolving body is arranged in the circumferential direction of the valve needle, and the generatrix of the outer contour of the revolving body and the axial section line of the expansion cavity form a streamline matching relation in the stroke of the valve needle. The throttling gap is finely adjusted through the axial displacement of the valve needle, and the axial impact of high-pressure airflow on the valve needle is decomposed; the expansion cavity is optimized to be of an asymmetric streamline structure and is matched with the outline of the valve needle, and linear adjustment of flow and stable output of pressure in the range from high pressure to medium pressure are achieved.

Description

Technical Field

[0001] This invention relates to nitrogen storage equipment accessories, specifically to a manual nitrogen pump pressure reducer. Background Technology

[0002] In the shipbuilding industry, the sealing test of piping systems often uses the nitrogen pump pressure method. Currently, common pump pressure requirements can be divided into two categories: one is low-pressure leak detection conditions such as air conditioning and refrigeration systems, with a pressure range usually between 0.00-1.5MPa. This can generally be achieved safely and controllably by using commercially available pressure reducers in conjunction with connecting pipes and fittings.

[0003] Another category involves pipelines operating at even higher pressures. For example, the pump pressure requirements for high-pressure pipelines in refrigeration systems and condenser chambers can reach approximately 2.5 MPa, while the test pressure for pipelines on LPG and other liquefied gas transport vessels even requires 3.0-4.0 MPa. Under these medium-to-high pressure conditions, ordinary pressure regulators are unsuitable due to their limited rated operating range. Traditionally, pressure regulators are often omitted, and nitrogen cylinder valves are manually operated directly via connecting pipes for pressurization. This method presents significant safety hazards: due to the lack of reliable pressure regulation and stabilization mechanisms, the intake pressure is difficult to control precisely during operation, making sudden pressure increases or fluctuations highly likely. If the valve is opened too quickly or too wide, instantaneous overpressure may cause the charging pipeline to rupture, leading to equipment damage or personal injury.

[0004] Therefore, existing technologies have problems with low control accuracy and insufficient safety in nitrogen pump pressurization operations in medium and high pressure ship pipelines. Summary of the Invention

[0005] The purpose of this invention is to overcome the technical problems mentioned in the background art.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows.

[0007] A manual nitrogen pump pressure reducer includes an inlet pipe, one end of which is connected to a nitrogen source, and the other end is a pressure-reducing gas outlet; it also includes a valve body, which is fixedly disposed in the radial direction of the inlet pipe; a threaded rod is disposed inside the valve body; a valve needle is fixedly disposed at one end of the threaded rod near the inlet pipe, and the valve needle extends to the inner side of the inlet pipe; a handle passes through the valve body and is connected to the threaded rod, and the handle drives the threaded rod to rotate, thereby causing the valve needle to move axially to change the throttling gap between the valve needle and the inlet pipe; the inlet pipe has an expansion cavity inside which the throttling gap cooperates with the valve needle, and the valve needle is adapted to the expansion cavity.

[0008] As a preferred technical solution, the axial direction of the valve body is inclined to the axial direction of the air intake pipe, and the included angle α between the two is 30° to 60°.

[0009] As a preferred technical solution, the expansion cavity has an asymmetrical structure, the top of the expansion cavity is a first arc-shaped surface that is smoothly transitioned from the inner wall; the bottom of the expansion cavity is provided with a flow guiding protrusion, the surface of the flow guiding protrusion is a second arc-shaped surface, the radius of curvature of the first arc-shaped surface is greater than the radius of curvature of the second arc-shaped surface, the first arc-shaped surface is located upstream of the valve needle, and the second arc-shaped surface is located downstream of the valve needle.

[0010] As a preferred technical solution, the valve needle is provided with a rotating body in the circumferential direction. During the rotation process, the rotating body is located in the axial stroke of the valve body. Its outer contour generatrix and the axial section line of the expansion cavity form a streamlined fit relationship, so that the width of the throttling gap formed between the rotating body and the expansion cavity changes at a uniform rate along the airflow direction.

[0011] As a preferred technical solution, the rotating body includes a first conical surface located on the upper part of the valve needle and adapted to the first arc-shaped surface, wherein the cone angle of the first conical surface matches the shape of the first arc-shaped surface.

[0012] As a preferred technical solution, the rotating body includes a second conical surface located below the valve needle and adapted to the second arc-shaped surface, wherein the cone angle of the second conical surface matches the shape of the second arc-shaped surface.

[0013] As a preferred technical solution, a sealing assembly is sequentially arranged axially between the push thread rod and the valve body. The sealing assembly includes two O-rings sleeved around the circumference of the push thread rod. The O-rings are interference-fitted with the inner side of the valve body, and an annular grease reservoir is formed between the two O-rings.

[0014] As a preferred technical solution, the ratio of the maximum cross-sectional area of ​​the expansion cavity to the cross-sectional area of ​​the inner diameter of the air intake pipe is controlled at 2~4:1.

[0015] As a preferred technical solution, the ratio of the maximum cross-sectional area of ​​the first arc-shaped surface region upstream of the valve needle to the cross-sectional area of ​​the inner diameter of the main body of the intake pipe is 1.2~1.8:1; the ratio of the maximum cross-sectional area of ​​the second arc-shaped surface region downstream of the valve needle to the cross-sectional area of ​​the inner diameter of the main body of the intake pipe is 2.5~3.5:1.

[0016] As a preferred technical solution, a pressure monitoring gauge is also installed downstream of the air intake pipe, and the range of the pressure monitoring gauge is 1.3-1.5 times the design limit pressure of the pressure reducer.

[0017] The advantages and beneficial effects of this invention are as follows: Traditional direct valve opening for gas filling is essentially a switch-on operation, and pressure regulation relies on the operator's experience and feel. Under high pressure, it is extremely easy for the downstream pipeline to experience instantaneous overpressure due to excessively rapid opening, which could lead to a burst risk. This invention replaces the switch with a needle valve-type throttling principle, using the axial displacement of the valve needle to continuously and smoothly adjust the throttling area, thereby optimizing the rate of change of the throttling gap along the airflow direction and achieving a linear relationship between the output pressure and the valve needle displacement.

[0018] This invention eliminates the need for mechanical transmission to drive the valve needle. The valve body is inclined at 30°-60° to the pipeline axis, thus decomposing the axial impact force of the high-pressure airflow on the valve needle. Simultaneously, the differentiated expansion ratios of the upstream and downstream expansion chambers form a gradually expanding tube, smoothly converting the kinetic energy of the throttled high-speed airflow into pressure energy, suppressing eddies and whistling, and ensuring stable output pressure. This device, with its simple structure and controllable cost, meets the special operating conditions of medium-high pressure nitrogen pumps (1.5MPa to 4.0MPa) in the shipbuilding industry, filling a market gap. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the internal structure of the pressure reducer shown in this invention.

[0020] Figure label: 1-Inlet pipe, 2-Pressure-reducing gas outlet, 3-Valve body, 4-Propulsion threaded rod, 5-Valve needle, 6-Handle, 7-Expansion cavity, 8-First arc-shaped surface, 9-Guide protrusion, 10-Second arc-shaped surface, 11-First conical surface, 12-Second conical surface, 13-Pressure monitoring gauge. Detailed Implementation

[0021] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0022] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly or implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] Please see Figure 1 This invention provides a manual nitrogen pump pressure reducer. One end of the inlet pipe 1 is connected to a nitrogen source, and the other end is a pressure-reducing gas outlet 2. The inlet pipe 1 can be made of high-strength seamless steel pipe or forged valve body. Its connection end with the high-pressure nitrogen source is usually equipped with a standard high-pressure threaded interface or quick-connect coupling to ensure reliable connection and sealing. The wall thickness of the inlet pipe 1 needs to be determined by strength calculation based on the maximum design inlet pressure. The pressure-reducing gas outlet 2 can be configured with a corresponding transition joint or flange according to the interface specifications of the downstream pressurized pipeline.

[0025] The pressure reducer also includes a valve body 3, which is fixedly mounted radially in the intake pipe 1. The valve body 3 contains a threaded rod 4, typically precision-machined from medium carbon steel or alloy steel after integral forging. The connection between the valve body 3 and the intake pipe 1 can be achieved by welding or bolting via the valve body mounting flange 19, ensuring no leakage under high pressure and sufficient rigidity. The valve body 3 has precision-machined threaded holes and smooth holes to accommodate and guide the threaded rod 4. The threaded rod 4 preferably uses fine-pitch trapezoidal or rectangular threads.

[0026] The valve needle 5 is fixed to one end of the threaded rod 4 near the intake pipe 1 and extends into the inner cavity of the intake pipe 1. The portion of the valve needle 5 that extends into the intake pipe 1 must undergo high-precision grinding and polishing to reduce flow resistance and improve erosion resistance. Its diameter and length must be calculated based on the designed flow rate and pressure regulation range.

[0027] Handle 6 passes through valve body 3 and connects to push threaded rod 4, driving push threaded rod 4 to rotate, which in turn drives valve needle 5 to move axially, thereby changing the throttling clearance between valve needle 5 and the inner wall of intake pipe 1. Handle 6 can be a T-shaped handle directly fixed to the tail end of push threaded rod 4, or an extended rod handle connected by a key or square head, to adapt to different operating spaces. The number of rotations of handle 6 is proportional to the displacement of valve needle 5, and the operator can make a preliminary judgment on the opening degree by observing the handle angle or the number of rotations.

[0028] To optimize the flow field after throttling, promote smooth pressure recovery, and suppress eddies and noise, the intake duct 1 has an expansion cavity 7 within its throttling region that mates with the valve needle 5. The circumferential profile of the valve needle 5 is adapted to the shape of the inner wall of the expansion cavity 7. The expansion cavity 7 is a localized cavity formed by machining on the inner wall of the intake duct 1.

[0029] The valve body 3 is inclined to the axial direction of the intake pipe 1, and the included angle α between them is 30° to 60°.

[0030] When the included angle α is 45°, the axial impact force of the high-pressure airflow on the valve needle 5 can be decomposed into approximately equal axial and radial components, thereby reducing the axial load acting on the threaded joint of the push screw 4 and making the operating torque of the handle 6 more stable, especially at the moment of opening the high pressure differential. This angle design also makes the axis of the valve needle 5 oblique to the direction of the main airflow, and some airflow will slide along the conical surface of the valve needle 5, which helps to reduce material fatigue at the root of the valve needle 5.

[0031] In some preferred embodiments, the expansion cavity 7 has an asymmetrical structure. The top of the expansion cavity 7 is a first arc-shaped surface 8 that smoothly transitions from the inner wall. The bottom of the expansion cavity 7 is provided with a flow-guiding protrusion 9, the surface of which is a second arc-shaped surface 10. The radius of curvature of the first arc-shaped surface 8 is greater than the radius of curvature of the second arc-shaped surface 10. Furthermore, the first arc-shaped surface 8 is located upstream of the valve needle 5, and the second arc-shaped surface 10 is located downstream of the valve needle 5.

[0032] The large radius of curvature of the first arc surface 8 allows the flow channel upstream of the valve needle 5 to expand slowly, and the airflow is initially stabilized before throttling, avoiding flow separation caused by sudden contraction.

[0033] The guide protrusion 9 and its second arc-shaped surface 10 with a large curvature form a steep slope. Its function is to force the high-speed gas to quickly adhere to its surface, turn and expand after the valve needle 5 opens to form the minimum throttling section (throat). By using the wall adhesion effect to guide the streamline, the conversion of kinetic energy to pressure energy is more concentrated and efficient, thereby reducing the eddies, oscillations and noise caused by the disorderly diffusion of free gas in the downstream pipeline.

[0034] When the valve needle 5 is fully closed, its second conical surface 12 is tightly fitted with the second arcuate surface 10 at the bottom of the expansion cavity 7, forming a sealed contact. The throttling gap is zero, and the airflow channel is completely blocked. As the handle 6 rotates counterclockwise, the push threaded rod 4 drives the valve needle 5 to move axially upward. The valve needle 5 first disengages from the second arcuate surface 10, forming an initial throttling gap downstream, through which high-pressure nitrogen can enter the downstream region of the expansion cavity 7. As the valve needle 5 continues to move upward, the region of its gradually decreasing diameter first conical surface 11 also gradually enters the upstream cavity space enclosed by the first arcuate surface 8. At this time, the airflow not only undergoes throttling and pressure reduction through the gap between the downstream second conical surface 12 and the second arcuate surface 10, but can also simultaneously undergo auxiliary throttling and guidance through the gradually increasing annular channel between the upstream first conical surface 11 and the first arcuate surface 8, forming a dual-path throttling system that improves the linearity and stability of flow regulation.

[0035] In addition, the first arc-shaped surface 8 and the second arc-shaped surface 10 of the expansion cavity 7 gradually transition to each other on the left and right sides (i.e., perpendicular to the airflow direction), and smoothly connect with the straight section of the intake pipe 1, so that the circumferential rotating body of the valve needle 5 ensures that the throttling gap is uniform and consistent throughout the entire circumference during the process of cooperating with the expansion cavity 7.

[0036] To achieve optimal matching between the valve needle 5 and the expansion cavity 7 throughout the entire stroke, and to make the change in the throttling gap more in line with the linear requirements of flow regulation, a rotating body is provided circumferentially on the valve needle 5. During the axial movement of the valve needle 5, the outer contour generatrix of this rotating body and the axial section line of the expansion cavity 7 form a streamlined fit, ensuring that the rate of change of the width of the throttling gap formed between the rotating body and the expansion cavity 7 along the airflow direction remains uniform.

[0037] The streamlined fit relationship refers to the flow channel formed by the outline of the valve needle 5 and the inner wall of the expansion cavity 7 at any opening degree, where the change of the equivalent diameter is as smooth as possible to avoid abrupt changes in cross-section.

[0038] The rotating body includes a first conical surface 11 located on the upper part of the valve needle 5 and adapted to the first arcuate surface 8. The cone angle of the first conical surface 11 matches the shape of the first arcuate surface 8 and is typically small, for example, 5° to 15°. At a small opening, the first conical surface 11 and the first arcuate surface 8 mainly form a long and narrow annular slit flow channel. The small cone angle makes the slit length relatively long, which has a throttling and pressure-reducing effect on the high-pressure gas. At the same time, since the slit gradually expands slightly along the path, it helps to prevent impurities from getting stuck here and makes the micro-flow adjustment more precise and stable.

[0039] The rotating body may also include a second conical surface 12 located below the valve needle 5 and adapted to the second arcuate surface 10. The cone angle of the second conical surface 12 matches the shape of the second arcuate surface 10 and is greater than the cone angle of the first conical surface 11, for example, 25° to 45°.

[0040] As the valve needle 5 moves downward, the second conical surface 12 gradually enters the mating area with the second arcuate surface 10; the throat area formed by the two increases rapidly, and the flow capacity increases dramatically. The large cone angle of the second conical surface 12 and the steep curvature of the second arcuate surface 10 work together to enable the high-speed airflow to spread rapidly along a funnel shape after passing through the minimum cross-section, thus maintaining good pressure recovery capability and flow stability even at a large flow rate.

[0041] To ensure reliable dynamic sealing of the feed screw 4 during reciprocating motion under high pressure and prevent nitrogen leakage along the screw body, a sealing assembly is sequentially installed axially between the feed screw 4 and the valve body 3. The sealing assembly includes two O-rings fitted around the circumference of the feed screw 4, with an interference fit to the inner side of the valve body 3. An annular grease reservoir is formed between the two O-rings.

[0042] O-rings should ideally be made of high-pressure and gas-resistant materials such as hydrogenated nitrile rubber (HNBR) or fluororubber (FKM). Special high-pressure grease can be periodically injected into the annular grease reservoir through the grease filler nozzle 18 on the valve body 3. This grease not only lubricates the threaded joint and the sealing ring, but its presence in the reservoir also forms a liquid seal barrier, balancing the pressure between the two sealing rings, compensating for minor wear, thus extending the seal life and ensuring no visible leakage at the stem seal even under frequent operation.

[0043] To achieve optimal matching between the valve needle 5 and the expansion cavity 7 throughout the entire stroke, and to make the change in the throttling gap more in line with the linear requirements of flow regulation, a rotating body is provided circumferentially on the valve needle 5. During the axial movement of the valve needle 5, the outer contour generatrix of this rotating body and the axial section line of the expansion cavity 7 form a streamlined fit, ensuring that the rate of change of the width of the throttling gap formed between the rotating body and the expansion cavity 7 along the airflow direction remains uniform.

[0044] To ensure that the expansion chamber 7 has sufficient pressure recovery capability, and to avoid airflow separation or excessive equipment size due to over-expansion, the ratio of the maximum cross-sectional area of ​​the expansion chamber 7 to the cross-sectional area of ​​the inner diameter of the intake pipe 1 is controlled between 2:1 and 4:1.

[0045] If the ratio is less than 2:1, the pressure recovery is insufficient and the outlet pressure fluctuates greatly; if the ratio is greater than 4:1, not only will the manufacturing difficulty increase, but the excessively large cavity will easily form a dead zone at low flow rates, accumulating impurities or condensate.

[0046] The ratio of the maximum cross-sectional area of ​​the first arc-shaped surface 8 region upstream of the valve needle 5 to the cross-sectional area of ​​the main body inner diameter of the intake duct 1 is 1.2:1 to 1.8:1; the ratio of the maximum cross-sectional area of ​​the second arc-shaped surface 10 region downstream of the valve needle 5 to the cross-sectional area of ​​the main body inner diameter of the intake duct 1 is 2.5:1 to 3.5:1. The upstream region uses a smaller expansion ratio to moderately rectify and pre-expand the airflow after initial throttling by the first conical surface 11 of the valve needle 5 without excessively reducing the flow velocity, thus preparing for the downstream main diffusion. The downstream region uses a larger expansion ratio to provide sufficient expansion space for the high-speed airflow after main throttling, ensuring that its kinetic energy is converted into pressure energy to the maximum extent and smoothly.

[0047] To visually monitor the output pressure after decompression, ensure operational safety, and allow for precise setting when necessary, a pressure monitoring gauge 13 is installed downstream of the intake pipe 1. The range of the pressure monitoring gauge 13 is 1.3-1.5 times the design limit pressure of the pressure reducer. The pressure monitoring gauge 13 should be a marine oil-filled pressure gauge with good shock resistance and an accuracy class of not less than 1.6.

[0048] Pressure monitoring gauge 13 can be connected to a pipe near the depressurized gas outlet 2 via a short pressure tap with a damping orifice to reduce the effect of pressure pulsation on the gauge needle and obtain a stable reading.

[0049] During operation, connect a high-pressure nitrogen source (pressure up to 10-12 MPa) to the inlet of inlet pipe 1. Initially, rotating handle 6 counterclockwise causes the threaded rod 4 to rotate and retract, thereby lifting valve needle 5 away from expansion chamber 7, maximizing the throttling clearance. If the cylinder valve is opened directly at this point, high-pressure nitrogen will rush into the downstream pipeline at high speed with almost no obstruction, easily causing an overpressure hazard.

[0050] According to the pressure reducer of the present invention, first ensure that the handle 6 is in the closed position with the valve needle 5 turned to the foremost position. Then, slowly open the main valve of the high-pressure nitrogen source. Next, rotate the handle 6. The rotation of the handle 6 is converted into a small and precise axial displacement of the valve needle 5 through the push thread rod 4. The valve needle 5 first approaches the first arcuate surface 8 with its first conical surface 11, forming an extremely narrow annular gap. When the high-pressure nitrogen passes through this gap, it is subjected to severe throttling, pressure energy is converted into kinetic energy, the flow velocity increases sharply, and the pressure drops significantly. The high-speed airflow after the initial throttling then enters the slow-diffusion section formed by the first arcuate surface 8, where the flow velocity decreases slightly, the pressure recovers slightly, and the flow state is initially stabilized. As the valve needle 5 continues to move downward, the second conical surface 12 begins to interact with the second arcuate surface 10, forming the main throttling throat. After passing through this throat, the airflow enters the rapid-diffusion section guided by the second arcuate surface 10. Here, due to the rapid expansion of the flow cross section, the kinetic energy of the high-speed airflow is effectively and smoothly converted back into pressure energy, and finally a stable medium-high pressure nitrogen output is obtained at the depressurized gas outlet 2, which is lower than the inlet pressure and can be continuously adjusted according to the opening degree of valve needle 5.

[0051] Throughout the process, the operator can precisely, linearly, and safely control the output pressure by observing the pressure monitoring gauge 13 at the outlet and finely adjusting the angle of the handle 6, perfectly adapting to the 1.5MPa to 4.0MPa nitrogen pump pressure leak detection requirements of marine pipelines. The inclined installation of the valve body 3 reduces the axial load on the valve needle 5, and the asymmetric expansion cavity 7 and the design that adapts to the profile of the valve needle 5 ensure stable flow and low noise across the entire flow range.

[0052] Example 1 In this embodiment, the inner diameter of the air intake pipe 1 is designed to be 8mm. The angle α between the axial direction of the valve body 3 and the axial direction of the air intake pipe 1 is designed to be 45°. The ratio of the maximum cross-sectional area of ​​the expansion cavity 7 to the cross-sectional area of ​​the air intake pipe 1 is 3:1, wherein the maximum cross-sectional area ratio of the first arc-shaped surface 8 is 1.5:1, and the maximum cross-sectional area ratio of the second arc-shaped surface 10 is 2.8:1. The cone angle of the first conical surface 11 is designed to be 10°, and the cone angle of the second conical surface 12 is designed to be 35°. The sealing assembly between the push threaded rod 4 and the valve body 3 adopts two HNBR O-ring seals, and the annular grease reservoir between them is injected with high-pressure resistant silicone-based grease through a filling nozzle. A 1.6-grade marine pressure gauge with a range of 0-6MPa is installed at the outlet as a pressure monitoring gauge 13.

[0053] The pressure regulator of this embodiment can continuously and stably adjust the outlet pressure within the range of 1.5 MPa to 4.0 MPa when reducing the pressure of high-pressure nitrogen gas with an inlet pressure of 12.0 MPa. The setting error of the outlet pressure can be controlled within ±0.1 MPa via handle operation. During steady-state output, the pointer swing amplitude of the pressure monitoring gauge 13 is less than ±1.5% of the full scale, indicating that the pressure fluctuation after pressure reduction is minimal.

[0054] Example 2 Based on Example 1, the geometric parameters of the expansion cavity 7 are changed. The ratio of the maximum cross-sectional area of ​​the expansion cavity 7 to the cross-sectional area of ​​the intake pipe 1 is adjusted to 2.5:1, with the maximum cross-sectional area ratio of the first arc-shaped surface 8 region adjusted to 1.3:1 and the maximum cross-sectional area ratio of the second arc-shaped surface 10 region adjusted to 2.2:1. The cone angle of the second conical surface 12 of the valve needle 5 is adjusted to 30° to better match the curvature of the modified second arc-shaped surface 10. Other structures are the same as in Example 1.

[0055] Compared to Example 1, the overall size of the expansion cavity 7 in this embodiment is more compact. Quantitative tests show that, at an output pressure of 3.0 MPa, its pressure fluctuation rate is slightly higher than that of Example 1 by about 0.5%, but it can still be controlled within an excellent range of ±2%.

[0056] Comparative Example 1 Comparative Example 1 simulates the primitive inflation method described in the background section. It lacks an independent depressurization structure; it relies solely on a high-pressure metal hose, with one end connected to a 12.0 MPa nitrogen cylinder valve and the other end directly connected to the ship's pipeline to be pressurized. Operation depends entirely on manually and slowly opening the cylinder valve.

[0057] When pressurizing nitrogen, the operator attempts to pressurize the container to 2.5 MPa. Due to the lack of pressure reduction and buffering mechanisms, the high-pressure gas violently impacts the empty container the moment the valve is opened, causing the pressure gauge needle to rise rapidly. Even experienced operators, operating extremely slowly, find it difficult to accurately control the pressure rise curve. The final pressurization result is either excessively long pressurization time or pressure exceeding the set value due to slight hand tremors. Approaching the target pressure, pressure fluctuations are severe, with the needle swinging by more than ±0.5 MPa (more than ±10% of full scale). Furthermore, the initial pressurization phase is often accompanied by strong gas whistling and pipeline vibration, posing significant safety risks.

[0058] Comparative Example 2 Comparative Example 2 uses a commercially available oxygen pressure regulator (its nominal maximum inlet pressure is 15 MPa, but the factory-set maximum outlet pressure is usually 1.25 MPa or lower). It is connected to a 12.0 MPa nitrogen source, and an attempt is made to adjust it to an output pressure of 2.5 MPa.

[0059] When reducing the pressure of nitrogen, the pressure regulator can be adjusted normally in the initial stage. However, when attempting to adjust the outlet pressure beyond the design range of its internal spring and diaphragm system, the free travel of the adjusting handle increases, and the outlet pressure changes very little even after multiple rotations. When the pressure approaches 2.0 MPa, the pressure regulator emits a noticeable whistling sound, and the internal diaphragm may be in an unstable vibration state. In addition, the outlet pressure cannot be stabilized at 2.5 MPa, and the pressure gauge pointer continues to rise slowly or exhibits periodic oscillations with a fluctuation range exceeding ±0.3 MPa.

[0060] Comparative Example 3 Comparative Example 3 uses a high-quality shut-off needle valve directly connected in series in the pipeline as a throttling element, equipped with independent inlet and outlet pressure gauges, to simulate a possible simple improvement scheme. The needle valve is installed at a vertical angle.

[0061] When using this needle valve to regulate the pressure reduction of high-pressure nitrogen, precise control is possible at small openings. However, as the opening increases, attempting to adjust the output pressure to 2.5 MPa or higher, the valve core, being a simple cone, creates a poorly shaped throttling gap with the inner wall of the straight pipe section. This results in a rapid expansion of the airflow downstream of the valve, generating strong vortices and producing a sharp noise. Furthermore, at a fixed opening, the outlet pressure fluctuates significantly, with fluctuations exceeding ±0.2 MPa. The high-pressure airflow vertically impacts the valve needle tip, making the adjustment feel heavy and uneven. Especially under high pressure differentials, even slight handle rotations can lead to large pressure jumps, resulting in poor linearity.

[0062] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A manual nitrogen pump pressure reducer, comprising an inlet pipe (1), one end of which is connected to a nitrogen source, and the other end being a pressure-reducing gas outlet; characterized in that: It also includes a valve body (3), which is fixedly disposed in the radial direction of the air intake pipe (1); a push thread rod (4) is disposed inside the valve body (3); a valve needle (5) is fixedly disposed at one end of the push thread rod (4) near the air intake pipe (1), and the valve needle (5) extends to the inside of the air intake pipe (1); a handle (6) passes through the valve body (3) and is connected to the push thread rod (4), and the handle (6) drives the push thread rod (4) to rotate and drive the valve needle (5) to move along its axial direction to change the throttling gap between the valve needle (5) and the air intake pipe (1); the air intake pipe (1) is provided with an expansion cavity (7) in the throttling gap that cooperates with the valve needle (5), and the valve needle (5) is adapted to the expansion cavity (7).

2. The manual nitrogen pump pressure reducer according to claim 1, characterized in that: The axial direction of the valve body (3) is inclined to the axial direction of the air intake pipe (1), and the included angle α between them is 30° to 60°.

3. The manual nitrogen pump pressure reducer according to claim 1, characterized in that: The expansion cavity (7) has an asymmetrical structure. The top of the expansion cavity (7) is a first arc-shaped surface (8) that is smoothly transitioned from the inner wall. The bottom of the expansion cavity (7) is provided with a flow guide protrusion (9). The surface of the flow guide protrusion (9) is a second arc-shaped surface (10). The radius of curvature of the first arc-shaped surface (8) is greater than the radius of curvature of the second arc-shaped surface (10). The first arc-shaped surface (8) is located upstream of the valve needle (5), and the second arc-shaped surface (10) is located downstream of the valve needle (5).

4. A manual nitrogen pump pressure reducer according to claim 3, characterized in that: The valve needle (5) is circumferentially provided with a rotating body. During the rotation process, the rotating body is located in the axial stroke of the valve body (3). Its outer contour generatrix and the axial section line of the expansion cavity (7) form a streamlined fit relationship, so that the width of the throttling gap formed between the rotating body and the expansion cavity (7) remains uniform along the airflow direction.

5. A manual nitrogen pump pressure reducer according to claim 4, characterized in that: The rotating body includes a first conical surface (11) located on the upper part of the valve needle (5) and adapted to the first arc-shaped surface (8), wherein the cone angle of the first conical surface (11) matches the shape of the first arc-shaped surface (8).

6. A manual nitrogen pump pressure reducer according to claim 4, characterized in that: The rotating body includes a second conical surface (12) located below the valve needle (5) and adapted to the second arcuate surface (10), the cone angle of the second conical surface (12) matching the shape of the second arcuate surface (10).

7. A manual nitrogen pump pressure reducer according to claim 1, characterized in that: A sealing assembly is sequentially arranged axially between the threaded rod (4) and the valve body (3). The sealing assembly includes two O-rings sleeved around the threaded rod (4). The O-rings are interference-fitted with the inner side of the valve body (3), and an annular grease reservoir is formed between the two O-rings.

8. A manual nitrogen pump pressure reducer according to claim 1, characterized in that: The ratio of the maximum cross-sectional area of ​​the expansion cavity (7) to the cross-sectional area of ​​the inner diameter of the air intake pipe (1) is controlled at 2~4:

1.

9. A manual nitrogen pump pressure reducer according to claim 3, characterized in that: The ratio of the maximum cross-sectional area of ​​the first arc-shaped surface (8) region upstream of the valve needle (5) to the cross-sectional area of ​​the inner diameter of the main body of the intake pipe (1) is 1.2~1.8:1; the ratio of the maximum cross-sectional area of ​​the second arc-shaped surface (10) region downstream of the valve needle (5) to the cross-sectional area of ​​the inner diameter of the main body of the intake pipe (1) is 2.5~3.5:

1.

10. A manual nitrogen pump pressure reducer according to claim 1, characterized in that: A pressure monitoring gauge (13) is also installed downstream of the air intake pipe (1), and the range of the pressure monitoring gauge (13) is 1.3-1.5 times the design limit pressure of the pressure reducer.

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