An exhaust pipe valve structure and method for a hydrogen cylinder liner roll-molding

Abstract

The application discloses a kind of exhaust pipe valve structures and methods of hydrogen cylinder inner container rotomolding, including sleeve and exhaust pipe, sleeve is used to be set in the bottle mouth of hydrogen cylinder inner container, one end of sleeve is communicated with the axial extension of shaking gas-permeable component, shaking gas-permeable component is elastic flexible component, shaking gas-permeable component is distributed with hollow gas-permeable structure, the outside of shaking gas-permeable component is wrapped with first net bag;Exhaust pipe is set in sleeve, and annular air passage is formed between the outer peripheral wall of exhaust pipe and the inner peripheral wall of sleeve, the wall of exhaust pipe is provided with vent hole, one end of exhaust pipe is provided with connecting head, connecting head is used to be detachably connected with inner container metal joint, exhaust pipe and sleeve are detachably connected by detachable connecting structure, the end of connecting head away from exhaust pipe is provided with valve nozzle communicated with exhaust pipe, solve the demoulding failure problem that traditional exhaust pipe is wrapped due to cooling shrinkage of molten material in the present IV type hydrogen storage cylinder inner container rotomolding.

Description

Technical Field

[0001] This invention relates to the field of Type IV hydrogen storage cylinder manufacturing technology, and in particular to a structure and method for rotomolding an exhaust pipe valve for a hydrogen cylinder liner. Background Technology

[0002] During rotational molding, hot air and small volatile molecules released from the material within the mold cavity must be effectively expelled through the venting structure. Poor venting can lead to defects such as bubbles and pinholes within the molded inner liner, severely impacting product quality.

[0003] Current technologies commonly employ a single metal vent pipe as the venting solution: one end of the pipe extends into the mold cavity, while the other end penetrates the outer wall of the mold, connecting to the external environment. However, this solution has significant drawbacks. During rotational molding, the molten polymer material is uniformly coated onto the cavity wall under the rotation of the mold, typically simultaneously encasing the outer wall of the vent pipe. Upon entering the cooling stage, the polymer material, due to its thermal shrinkage properties, adheres tightly to the outer wall of the vent pipe, forming a "lock-in" state. This leads to a dilemma during demolding: forcibly removing the vent pipe can easily tear the inner liner wall or cause the vent pipe to break within the cavity, directly resulting in product scrap; retaining the vent pipe fails to meet the precise dimensional requirements of subsequent inner liner processing (such as bottle neck welding and reinforcing layer winding). In many cases, due to the material's inherent mechanical properties, once the inner liner and vent pipe are locked together, demolding becomes impossible, directly leading to product scrap and significant economic losses.

[0004] To address this issue, the industry has attempted improvements such as using porous venting pipes or biodegradable venting cores. However, porous structures are prone to pore blockage under the molten material, resulting in a loss of venting function and potentially causing irreversible contamination and impact on related equipment in the rotational molding machine. Biodegradable core materials, on the other hand, pose a risk of degradation residues contaminating the inner liner material and affecting its long-term hydrogen resistance. None of the above solutions can meet the stringent safety, reliability, and durability requirements for Type IV hydrogen storage cylinder liners. Summary of the Invention The purpose of this invention is to provide a structure and method for venting valve in the rotational molding of hydrogen cylinder liner. Under the premise of ensuring the unobstructed flow of the venting channel, avoiding the formation of air bubbles and pinhole defects in the liner, and meeting the requirements of airtightness and hydrogen permeability resistance under hydrogen storage conditions, this invention solves the problem of demolding failure caused by the molten material being wrapped around the venting valve in the rotational molding of Type IV hydrogen storage cylinder liner.

[0005] The technical solution adopted to solve the above-mentioned technical problems is as follows: This invention provides a rotomolded exhaust pipe valve structure for a hydrogen cylinder liner, comprising: The sleeve is a hollow cylindrical tube structure. The sleeve is used to fit into the mouth of the inner liner of the hydrogen cylinder. One end of the sleeve is connected to a shaking and ventilating component that extends along the axis. The shaking and ventilating component is an elastic and flexible component. The shaking and ventilating component has a hollow ventilating structure. The outer side of the shaking and ventilating component is wrapped with a first net bag. An exhaust pipe is fitted inside the sleeve. An annular air passage is formed between the outer peripheral wall of the exhaust pipe and the inner peripheral wall of the sleeve. The pipe wall of the exhaust pipe is provided with at least one vent hole communicating with the annular air passage. A connector is provided at the end of the exhaust pipe away from the vibration and ventilation component. The connector is used to detachably connect to the inner liner metal joint. The exhaust pipe and the sleeve are detachably connected by a detachable connection structure. A valve is provided at the end of the connector away from the exhaust pipe, which communicates with the exhaust pipe. The valve is used to connect to a vacuum pump.

[0006] The beneficial effects of the exhaust pipe valve structure of the present invention are: This invention connects to the inner metal connector (boss) via a detachable connector, thereby fixing the entire vacuum exhaust path within the rotational molding mold. The exhaust pipe is detachably fitted into the sleeve, creating an annular air passage between the outer wall of the exhaust pipe and the inner wall of the sleeve, thus forming a continuous vacuum exhaust path. This path consists of: the rotational molding mold cavity, a first mesh bag, a perforated venting structure, an annular air passage, a vent hole, a connector, and a valve. Activating the vacuum equipment allows for continuous and stable vacuum extraction of the rotational molding mold cavity.

[0007] The core of this invention lies in using a sleeve as an isolation interface between the molding inner liner and the vent pipe, thus preventing the vent pipe from directly contacting the molten material. This fundamentally prevents the molten material from sticking to the outer wall of the vent pipe during cooling and shrinkage, thereby completely solving the problem of difficult demolding or even breakage of the vent pipe in traditional solutions. After processing, the vent pipe can be easily and reliably removed from the sleeve and the metal joint of the inner liner.

[0008] To ensure unobstructed venting throughout the rotational molding process, this invention employs multiple anti-clogging mechanisms: First, the first mesh bag effectively intercepts rotational molding powder, preventing it from entering and clogging the venting channel; second, during mold rotation, the shaking and venting components bend to varying degrees due to the shaking, automatically shaking off powder adhering to the first mesh bag, achieving self-cleaning and ensuring continuous and smooth venting.

[0009] As a further improvement to the above technical solution, the exhaust pipe is wrapped with a second net bag on its outer side.

[0010] As a further improvement to the above technical solution, the outer periphery of the connector is provided with an external thread that is threaded to the inner metal connector.

[0011] As a further improvement to the above technical solution, the outer periphery of the connector is provided with a limiting step facing one end of the exhaust pipe, and the limiting step is used to limit and abut against the end face of the inner liner metal connector and the rotational molding mold.

[0012] As a further improvement to the above technical solution, the outer wall of the sleeve is provided with an anti-stick coating.

[0013] As a further improvement to the above technical solution, the outer wall of the sleeve is set as a smooth curved surface or is provided with an anti-stick texture.

[0014] As a further improvement to the above technical solution, the vibration-ventilating component is a spring tube structure.

[0015] As a further improvement to the above technical solution, a clamping platform is provided at the end of the connector away from the exhaust pipe, and the clamping platform is used for clamping by an external clamping mechanism.

[0016] As a further improvement to the above technical solution, the detachable connection structure includes at least one snap-fit ​​component disposed on the exhaust pipe. The outer wall of the exhaust pipe is provided with a snap-fit ​​groove extending radially. The snap-fit ​​component includes a snap-fit ​​spring and a snap-fit ​​ball disposed sequentially in the snap-fit ​​groove. The inner wall of the sleeve is provided with an annular groove. The snap-fit ​​spring is used to provide elastic force for the snap-fit ​​ball to engage with the annular groove, so as to lock the relative position between the exhaust pipe and the sleeve in the axial direction.

[0017] Furthermore, this invention also proposes a rotational molding method for a hydrogen cylinder liner, applicable to the aforementioned exhaust pipe valve structure, wherein the rotational molding method for the hydrogen cylinder liner includes: The inner metal connector is fixed to the predetermined exhaust port of the rotational molding mold. The connector is mated with and locked to the inner metal connector, so that the sleeve and its internal exhaust pipe are stably positioned inside the rotational molding mold. Then, the valve nozzle is connected to the external vacuum equipment through the air pipe. The rotational molding process is started, and the rotational molding mold is controlled to rotate and heat along the set trajectory. The added rotational molding powder is evenly diffused and melted in the inner cavity of the rotational molding mold. During this process, the shaking and ventilating component that rotates with the rotational molding mold undergoes periodic bending and rebound due to centrifugal force and its own elasticity, shaking off the powder adhering to the surface of the first mesh bag, realizing online self-cleaning of the exhaust channel and preventing blockage. Turn on the vacuum equipment and continuously evacuate the inner cavity of the rotational molding mold according to the preset vacuum level of the process. After vacuuming and material melting are completed, the rotational molding mold is controlled to enter the cooling stage. The molten material is cooled and solidified in a vacuum environment, and finally formed into a hydrogen cylinder inner liner blank. After the inner liner has cooled and set, disconnect the connector from the metal joint of the inner liner, and then completely pull the exhaust pipe out of the sleeve. Remove the sleeve fixed to the inner wall of the hydrogen cylinder liner and a small amount of cooling material at its port to obtain the final hydrogen cylinder liner product with a complete structure and smooth inner wall.

[0018] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments; Figure 1 This is a schematic diagram of an embodiment of the exhaust pipe valve structure provided by the present invention, which adopts an automatic elastic locking detachable connection structure. Figure 2 yes Figure 1 The exploded diagram in the middle; Figure 3 This is an installation diagram of an embodiment of the exhaust pipe valve structure provided by the present invention, wherein the detachable connection structure is not shown. Figure 4 This is a schematic diagram of an embodiment of the exhaust pipe valve structure provided by the present invention, which adopts a threaded connection type detachable connection structure. Figure 5 This is a schematic diagram of an embodiment of the exhaust pipe valve structure provided by the present invention, which adopts a press-fit detachable connection structure. Figure 6 This is a flowchart of the rotational molding method for hydrogen cylinder liners provided by the present invention; Icon labels: Sleeve 100; Shaking and ventilation component 110; First net bag 120; Annular groove 130; Exhaust pipe 200; vent hole 210; connector 220; valve nozzle 221; limit step 222; clamping platform 223; second net bag 230; snap-fit ​​groove 240; snap-fit ​​spring 250; snap-fit ​​ball 260; Annular airway 300; Inner liner metal connector 400; 500mm mounting thread for secondary mounting; Button 600; spring clip 610; snap-fit ​​groove 620. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0021] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0022] In the description of this invention, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features or their sequential relationship.

[0023] In the description of this invention, unless otherwise explicitly defined, terms such as "setting," "installing," and "connecting" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are some embodiments of the present invention, not all embodiments.

[0025] Reference Figures 1-5 The exhaust pipe valve structure of the hydrogen cylinder liner formed by rotational molding of the present invention is provided in the following embodiment: like Figure 1 and Figure 2 As shown, the exhaust pipe valve structure of the present invention includes: a sleeve 100 and an exhaust pipe 200.

[0026] The sleeve 100 is a hollow cylindrical tube structure. In use, the sleeve 100 is used to fit into the mouth of the inner liner of the hydrogen cylinder. One end of the sleeve 100 is connected to a shaking and venting component 110 extending along the axis. The shaking and venting component 110 is an elastic and flexible component with a perforated venting structure. External gas can enter the sleeve 100 through the perforated venting structure.

[0027] like Figure 1 As shown, the outer side of the shaking and breathable component 110 in this embodiment is wrapped with a first mesh bag 120, wherein the first mesh bag 120 is made of a non-stick material to prevent powder from entering the sleeve 100.

[0028] The exhaust pipe 200 is fitted inside the sleeve 100, and the exhaust pipe 200 and the sleeve 100 are detachably connected by a detachable connection structure. An annular air passage 300 is formed between the outer peripheral wall of the exhaust pipe 200 and the inner peripheral wall of the sleeve 100. The annular air passage 300 is connected to the hollow ventilation structure. The pipe wall of the exhaust pipe 200 is provided with at least one vent hole 210 that communicates with the annular air passage 300. In this embodiment, the exhaust pipe 200 is provided with a plurality of vent holes 210 spaced apart along the axial direction.

[0029] The annular air passage 300 and multiple vent holes 210 can increase the exhaust volume and prevent the overall exhaust from failing due to the blockage of a single hole.

[0030] The exhaust pipe 200 of the present invention has a connector 220 at one end away from the vibration-ventilating component 110, such as... Figure 3 As shown, connector 220 is used to detachably connect to inner liner metal connector 400. One end of connector 220 away from exhaust pipe 200 is provided with valve nozzle 221 that communicates with exhaust pipe 200. Valve nozzle 221 is used to connect to vacuum equipment.

[0031] This invention uses the sleeve 100 as an isolation interface between the molding inner liner and the exhaust pipe 200, avoiding direct contact between the exhaust pipe 200 and the molten material. This fundamentally prevents the molten material from sticking to the outer wall of the exhaust pipe 200 during the cooling and shrinkage process, thus completely solving the problem of difficult demolding or even breakage of the exhaust pipe 200 in the traditional solution. After processing, the exhaust pipe 200 can be pulled out as a whole from the sleeve 100 and the inner liner metal joint 400. The demolding operation is simple and reliable.

[0032] In use, the present invention is connected to the inner liner metal connector 400 via a detachable connector 220, thereby fixing the entire vacuum exhaust path inside the rotational molding mold. The exhaust pipe 200 is fitted into the sleeve 100 via a detachable connection structure, forming an annular air passage 300 between the outer peripheral wall of the exhaust pipe 200 and the inner peripheral wall of the sleeve 100, which communicates with the inner cavity of the rotational molding mold, thus forming a continuous vacuum exhaust path. This path consists of: the inner cavity of the rotational molding mold, the first mesh bag 120, the perforated vent structure, the annular air passage 300, the vent hole 210, the connector 220, and the valve nozzle 221. Activating the vacuum pump allows for continuous and stable vacuum extraction of the inner cavity of the rotational molding mold.

[0033] To ensure unobstructed venting throughout the rotational molding process, this invention employs multiple anti-clogging mechanisms: First, the first mesh bag 120 effectively intercepts rotational molding powder, preventing it from entering and clogging the venting channel; second, during mold rotation, the shaking and venting component 110 bends to varying degrees due to shaking, automatically shaking off powder adhering to the first mesh bag 120, achieving self-cleaning and ensuring continuous and smooth venting.

[0034] The main body material of the exhaust pipe 200 and sleeve 100 of the present invention should be a high-temperature resistant metal or alloy material, specifically 304 stainless steel, TC4 titanium alloy or 316L stainless steel, etc.

[0035] The dimensions of the exhaust pipe 200 should be designed to match the dimensions of the inner liner and the BOSS, or modified based on the original exhaust pipe 200. However, the dimensions of the exhaust pipe 200 and the sleeve 100 should be smaller than the inner liner metal connector 400 and the inner liner diameter to facilitate easy disassembly and assembly and avoid interference.

[0036] The lengths of the vent pipe 200 and the sleeve 100 should be determined based on the inner liner size, thickness, and material feeding amount. The length of the vent pipe 200 should be higher than the upper plane of the material feeding amount. Secondly, the lengths of the vent pipe 200 and the sleeve 100 should be kept as short as possible to reduce the area covered by the cooled molten material, thereby reducing the difficulty of demolding.

[0037] Furthermore, such as Figure 1 As shown, the exhaust pipe 200 is wrapped with a second mesh bag 230 to add an extra layer of anti-clogging.

[0038] In this embodiment, the outer periphery of the connector 220 is provided with an external thread that is threaded to the inner metal connector 400.

[0039] And, as Figure 3 As shown, the outer periphery of the connector 220 is provided with a limiting step 222 facing one end of the exhaust pipe 200. The limiting step 222 is used to limit and abut against the end face of the inner metal connector 400 and the rotational molding mold to fix the entire exhaust pipe valve structure.

[0040] In this embodiment, the outer wall of the sleeve 100 is provided with an anti-stick coating. The anti-stick coating makes it easy for the sleeve 100 to be pulled out from the inner liner and also reduces the adhesion of the molten material. The anti-stick coating is polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), high-temperature silicone anti-stick coating, or ceramic anti-stick coating.

[0041] Furthermore, the outer wall of the sleeve 100 is configured as a smooth curved surface or is provided with an anti-stick texture to minimize the adhesion between the sleeve 100 and the molten material.

[0042] In this embodiment, the shaking and ventilating component 110 is a spring tube structure. The spring tube structure combines a certain degree of rigidity and flexibility, so that when it is horizontal, there will be a certain small gap and a certain degree of bending. During rotation, the bending of different degrees can shake off the adhering powder.

[0043] In this embodiment, the connector 220 is provided with a clamping platform 223 at the end away from the exhaust pipe 200. The clamping platform 223 is used for clamping by an external clamping mechanism. During assembly and disassembly, the exhaust pipe 200 is fixed by clamping the clamping platform 223.

[0044] The detachable connection structure can be selected from one or more combinations of automatic elastic engagement, threaded connection, or press-type engagement.

[0045] like Figure 1 and Figure 2 As shown, the detachable connection structure of this embodiment includes at least one snap-fit ​​assembly disposed on the exhaust pipe 200. Two snap-fit ​​assemblies are provided and symmetrically disposed on both sides of the exhaust pipe 200. The outer wall of the exhaust pipe 200 is provided with a snap-fit ​​groove 240 extending radially. The snap-fit ​​assembly includes a snap-fit ​​spring 250 and a snap-fit ​​ball 260 disposed sequentially in the snap-fit ​​groove 240. The snap-fit ​​spring 250 acts between the snap-fit ​​spring 250 and the bottom of the snap-fit ​​groove 240. The inner wall of the sleeve 100 is provided with an annular groove 130. The snap-fit ​​spring 250 is used to provide elastic force for the snap-fit ​​ball 260 to engage with the annular groove 130, so as to lock the relative position of the exhaust pipe 200 and the sleeve 100 in the axial direction.

[0046] During use, under the pressure of the inner wall of the sleeve 100, the locking ball 260 compresses the locking spring 250 and enters the annular groove 130 on the inner wall of the sleeve 100. Under the thrust of the locking spring 250, the locking ball 260 is inserted into the annular groove 130 along the locking groove 240 until it contacts the stopping position of the annular groove 130, so that the exhaust pipe 200 and the sleeve 100 are locked together in the vertical direction with a certain force.

[0047] During demolding, only an outward pulling force needs to be applied while loosening the connector 220 to cause the snap-fit ​​ball 260 to press against the snap-fit ​​spring 250, at which point the exhaust pipe 200 gradually separates from the sleeve 100.

[0048] In some other embodiments, such as Figure 4 As shown, the detachable connection structure adopts a threaded connection method. The detachable connection structure is mainly composed of the auxiliary mounting thread 500 that matches the outer wall of the exhaust pipe 200 and the inner wall of the sleeve 100. To ensure the convenience of disassembly and assembly, the auxiliary mounting thread 500 and the mounting thread between the connector 220 and the inner metal connector 400 should be consistent. During installation and separation, the connector 220 can be rotated synchronously to install and separate the entire exhaust pipe 200 and the exhaust pipe 200 and the sleeve 100 simultaneously.

[0049] In some other embodiments, such as Figure 5As shown, the detachable connection structure adopts a push-button type. The detachable connection structure mainly consists of a button 600 set on the clamping table 223, an elastic buckle 610 set on the exhaust pipe 200, and a locking groove 620 on the inner wall of the sleeve 100. The button 600 and the elastic buckle 610 are connected by a mechanical structure. When in use, the sleeve 100 only needs to be directly put into the exhaust pipe 200. The elastic buckle 610 extends into the locking groove 620 to form an axial lock. When demolding, the elastic buckle 610 can be retracted by clamping the clamping table 223 with a clamping tool, thereby releasing the axial lock between the exhaust pipe 200 and the sleeve 100 and demolding smoothly.

[0050] Furthermore, this invention also proposes a rotational molding method for hydrogen cylinder liners, applicable to exhaust pipe valve structures, such as... Figure 6 As shown, the rotational molding method for the inner liner of a hydrogen cylinder includes: Step S100: Fix the inner liner metal connector 400 to the predetermined exhaust port of the rotational molding mold, connect the connector 220 to the inner liner metal connector 400 and lock it, so that the sleeve 100 and its internal exhaust pipe 200 are stably positioned inside the rotational molding mold. Then, connect the valve nozzle 221 to the external vacuum equipment through the air pipe. Step S200: Start the rotational molding program, control the rotational molding mold to rotate and heat along the set trajectory, and the added rotational molding powder is evenly diffused and melted in the inner cavity of the rotational molding mold. During this process, the shaking and ventilating component 110, which rotates with the rotational molding mold, undergoes periodic bending and rebound due to centrifugal force and its own elasticity, shaking off the powder adhering to the surface of the first net bag 120, realizing online self-cleaning of the exhaust channel and preventing blockage. Step S300: Turn on the vacuum equipment and continuously evacuate the inner cavity of the rotational molding mold according to the preset vacuum level of the process. Step S400: After vacuuming and material melting are completed, the rotational molding mold is controlled to enter the cooling stage. The molten material is cooled and solidified in a vacuum environment, and finally formed into a hydrogen cylinder inner liner blank. Step S500: After the inner liner has cooled and set, disconnect the connector 220 from the metal connector 400 of the inner liner, and then completely pull out the entire exhaust pipe 200 from the sleeve 100. Step S600: Remove the sleeve 100 fixed to the inner wall of the hydrogen cylinder liner and a small amount of cooling material at its port to obtain a final hydrogen cylinder liner product with a complete structure and smooth inner wall.

[0051] In step S100, the clamping table 223 drives the connector 220 to rotate so as to connect with the inner metal connector 400. At the same time, the exhaust pipe 200 is driven to extend into the sleeve 100. Under the pressure of the inner wall of the sleeve 100, the locking ball 260 compresses the locking spring 250 and enters the annular groove 130 of the inner wall of the sleeve 100. Under the thrust of the locking spring 250, the locking ball 260 is inserted into the annular groove 130 along the locking groove 240 until it contacts the stopping position of the annular groove 130, so that the exhaust pipe 200 and the sleeve 100 form a certain force lock in the vertical direction.

[0052] In step S500, the connector 220 is rotated in the opposite direction to disengage it from the inner metal connector 400, causing the snap-fit ​​ball 260 to press the snap-fit ​​spring 250. At this time, the exhaust pipe 200 gradually disengages from the sleeve 100, and then the entire exhaust pipe 200 is completely pulled out from the sleeve 100.

[0053] In step S600, the sleeve 100 can be removed by cutting, at which point the sleeve 100 is a disposable consumable component, or the sleeve 100 can be pulled out.

[0054] Taking the PA12 inner liner of a 210L 70MPa Type IV hydrogen storage cylinder as an example: The inner metal connector 400 has a diameter of φ90mm, an internal thread of M64×2, and is made of 316L stainless steel; the valve nozzle 221 has a G1 / 2" interface and a pressure rating of ≥87.5MPa. The exhaust pipe 200 is made of quenched and tempered 40Cr steel with a temperature resistance of ≥300℃, an outer diameter of φ55mm, a length of 800mm, and 6 φ12mm vent holes 210. The sleeve 100 is made of 40Cr steel with a 0.2mm thick PTFE anti-stick coating. 40Cr is resistant to repeated disassembly and wear, and PTFE prevents molten material from sticking. Its inner diameter is φ60mm, forming a 2.5mm annular air passage 300 with the exhaust pipe 200. Its outer diameter is φ85mm, which is smaller than the diameter of the inner metal connector 400 to prevent interference.

[0055] Detachable connection structure: The snap-fit ​​ball 260 is φ8mm in size, made of No. 45 steel, with a quenching hardness of HRC45-50, which is wear-resistant and low in cost; the snap-fit ​​ball 260 is made of 65Mn spring steel with a stiffness coefficient of 5N / mm, which is resistant to repeated compression and costs only 1 / 4 of that of a 316L spring.

[0056] The first net bag 120 and the second net bag 230 are made of 100-mesh PTFE mesh.

[0057] The valve nozzle 221 has a G1 / 2" interface, made of 40Cr steel with nickel plating, and a pressure resistance of ≥87.5MPa.

[0058] First, clamp the clamping table 223 to fix the entire exhaust pipe 200, then fix the sleeve 100 and the spring tube structure, align the exhaust pipe 200 with the gap in the sleeve 100 and the spring tube structure and insert it. As the insertion depth increases, when the locking ball 260 touches the sleeve 100, the locking balls 260 on both sides are forced to compress the locking spring 250. At this time, the locking spring 250 is compressed and stores energy, and the locking ball 260 enters the annular groove 130. Then the locking spring 250 reduces the compression and slowly returns to its original position until the locking ball 260 enters the bottom of the annular groove 130. At this point, a certain force is formed between the exhaust pipe 200 and the sleeve 100 in the axial direction to lock them together.

[0059] Subsequently, a second net bag 230 and a first net bag 120 are fixed to the surface of the exhaust pipe 200 body and the spring tube structure, respectively, to prevent powder from entering the exhaust pipe 200. Secondly, the inner liner metal connector 400 is fixed inside the exhaust end of the rotational molding mold, and the entire exhaust pipe valve structure is fixed outside the exhaust end of the rotational molding mold by clamping and holding table 223. The entire exhaust device is inserted into the inner liner metal connector 400 and rotated to make the connector 220 engage with the inner liner metal connector 400 until the limiting step 222 fits against the end face of the limiting step 222.

[0060] After the inner wall of the rotational molding mold is cleaned, the release agent is applied, and the materials are fed in, the exhaust end of the rotational molding mold is closed, and the valve nozzle 221 is connected to the vacuum equipment through the air pipe to complete the preparation work before rotational molding.

[0061] Subsequently, the rotational molding process is initiated. As the rotational molding mold rotates, the material is diffused within the mold cavity, with some adhering to the first mesh bag 120. However, due to the bending and rebound of the spring tube structure during the rotational molding process, some of the material can be shaken off. At the same time, since the temperature has not reached the melting point of PA12 and the non-stick properties of the PTFE mesh bag itself, there is very little residual powder on the first mesh bag 120, ensuring smooth venting and preventing blockage of the first mesh bag 120. After the rotational molding mold is heated to 120°C and held for 35 minutes, a vacuum is drawn through the valve nozzle 221 to maintain a vacuum level of -0.095MPa. The venting path is as follows: rotational molding mold cavity → first mesh bag 120 → spring tube structure → annular air passage 300 → second mesh bag 230 → vent hole 210 → vent pipe 200 → valve nozzle 221.

[0062] Furthermore, during the cooling process, PA12, which covers the spring tube structure and sleeve 100, cools and contracts, clamping the spring tube structure and sleeve 100. At this time, valve nozzle 221 can be removed, connector 220 can be rotated in the opposite direction, and connector 220 can be disengaged from the inner liner metal joint 400. This causes snap-fit ​​ball 260 to press snap-fit ​​spring 250. At this time, exhaust pipe 200 gradually separates from sleeve 100 until connector 220 is completely disengaged from inner liner metal joint 400. Then snap-fit ​​ball 260 completely disengages from annular groove 130. At this time, exhaust pipe 200 is disengaged from sleeve 100, and exhaust pipe 200 can be easily removed. Finally, the sleeve 100 and part of the cooling material fixed to the inner wall of the inner liner are removed by the cutting mechanism to obtain a complete Type IV hydrogen storage cylinder inner liner.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A rotomolded exhaust pipe valve structure for a hydrogen cylinder liner, characterized in that, include: The sleeve is a hollow cylindrical tube structure. The sleeve is used to fit into the mouth of the inner liner of the hydrogen cylinder. One end of the sleeve is connected to a shaking and ventilating component that extends along the axis. The shaking and ventilating component is an elastic and flexible component. The shaking and ventilating component has a hollow ventilating structure. The outer side of the shaking and ventilating component is wrapped with a first net bag. An exhaust pipe is fitted inside the sleeve. An annular air passage is formed between the outer peripheral wall of the exhaust pipe and the inner peripheral wall of the sleeve. The pipe wall of the exhaust pipe is provided with at least one vent hole communicating with the annular air passage. A connector is provided at the end of the exhaust pipe away from the vibration and ventilation component. The connector is used to detachably connect to the inner liner metal joint. The exhaust pipe and the sleeve are detachably connected by a detachable connection structure. A valve is provided at the end of the connector away from the exhaust pipe, which communicates with the exhaust pipe. The valve is used to connect to a vacuum pump. The detachable connection structure includes at least one snap-fit ​​assembly disposed on the exhaust pipe. The outer wall of the exhaust pipe is provided with a snap-fit ​​groove extending radially. The snap-fit ​​assembly includes a snap-fit ​​spring and a snap-fit ​​ball disposed sequentially in the snap-fit ​​groove. The inner wall of the sleeve is provided with an annular groove. The snap-fit ​​spring is used to provide elastic force for the snap-fit ​​ball to engage with the annular groove, so as to lock the relative position of the exhaust pipe and the sleeve in the axial direction.

2. The exhaust pipe valve structure according to claim 1, characterized in that: The exhaust pipe is wrapped with a second mesh bag on the outside.

3. The exhaust pipe valve structure according to claim 1, characterized in that: The outer periphery of the connector is provided with an external thread that connects with the inner metal connector thread.

4. The exhaust pipe valve structure according to claim 3, characterized in that: The outer periphery of the connector is provided with a limiting step facing one end of the exhaust pipe. The limiting step is used to limit and abut against the end face of the inner metal connector and the rotational molding mold.

5. The exhaust pipe valve structure according to claim 1, characterized in that: The outer wall of the sleeve is provided with an anti-stick coating.

6. The exhaust pipe valve structure according to claim 1, characterized in that: The outer wall of the sleeve is configured as a smooth curved surface or is provided with an anti-stick texture.

7. The exhaust pipe valve structure according to claim 1, characterized in that: The vibration-ventilated component is a spring tube structure.

8. The exhaust pipe valve structure according to claim 1, characterized in that: The connector is provided with a clamping platform at the end away from the exhaust pipe, and the clamping platform is used for clamping by an external clamping mechanism.

9. A method for rotational molding of a hydrogen cylinder liner, characterized in that: The rotational molding method for the hydrogen cylinder liner, applicable to the exhaust pipe valve structure as described in any one of claims 1 to 8, comprises: The inner metal connector is fixed to the predetermined exhaust port of the rotational molding mold. The connector is mated with and locked to the inner metal connector, so that the sleeve and its internal exhaust pipe are stably positioned inside the rotational molding mold. Then, the valve nozzle is connected to the external vacuum equipment through the air pipe. The rotational molding process is started, and the rotational molding mold is controlled to rotate and heat along the set trajectory. The added rotational molding powder is evenly diffused and melted in the inner cavity of the rotational molding mold. During this process, the shaking and ventilating component that rotates with the rotational molding mold undergoes periodic bending and rebound due to centrifugal force and its own elasticity, shaking off the powder adhering to the surface of the first mesh bag, realizing online self-cleaning of the exhaust channel and preventing blockage. Turn on the vacuum equipment and continuously evacuate the inner cavity of the rotational molding mold according to the preset vacuum level of the process. After vacuuming and material melting are completed, the rotational molding mold is controlled to enter the cooling stage. The molten material is cooled and solidified in a vacuum environment, and finally formed into a hydrogen cylinder inner liner blank. After the inner liner has cooled and set, disconnect the connector from the metal joint of the inner liner, and then completely pull the exhaust pipe out of the sleeve. Remove the sleeve fixed to the inner wall of the hydrogen cylinder liner and a small amount of cooling material at its port to obtain the final hydrogen cylinder liner product with a complete structure and smooth inner wall.

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