BOSS structure for IV-type hydrogen storage bottle inner container

Abstract

The BOSS structure comprises an external structure and an internal structure, and the external structure sequentially comprises a mounting nut, a carbon fiber winding retaining structure, a positioning structure, a sealing ring groove, a barb boss structure and a web inner container connecting structure from top to bottom; the internal structure sequentially comprises a cylinder valve seat connecting internal thread, a plastic inner container connecting inner ring groove, an axial plastic shrinkage preventing structure and an inner container rotation stopping structure from top to bottom; the anti-axial plastic shrinkage structure is located at the position of an inner hole in the bottom of the BOSS structure, the inner container rotation stopping structure is designed on the extending face of the bottom of the BOSS structure, the slope chamfer angle size of the anti-axial plastic shrinkage structure ranges from 10 degrees to 85 degrees, and the chamfer size ranges from 1 mm to 10 mm. Plastic shrinkage is limited step by step through the annularly-distributed structure so as to relieve local thermal stress, the inner container rotation stopping structure is optimized, and the sealing effect between the inner container and the BOSS structure is enhanced through the synergistic effect of the barb grooves and the positioning structure. According to the structure, connection between the inner container and the BOSS is more stable, and the product yield is high.

Description

Technical Field

[0001] The present invention relates to the fields of special equipment and polymer material processing and forming, and specifically relates to a BOSS structure for the inner liner of a type-IV hydrogen storage cylinder. Background Art

[0002] A type-IV hydrogen storage cylinder is a storage gas cylinder in the field of high-pressure gaseous hydrogen storage. It has the characteristics of high pressure, fatigue resistance, hydrogen embrittlement prevention, and lightweight, and belongs to the scope of high-pressure containers. A type-IV hydrogen storage cylinder usually consists of an inner liner material barrier layer and a carbon fiber composite pressure-bearing layer. However, in actual use, the hydrogen storage cylinder is often installed in a hydrogen storage system. To ensure the reliable connection between the hydrogen storage cylinder and the external pipeline, a BOSS structure made of metal materials is conventionally used at the end of the hydrogen storage cylinder, and the materials are commonly stainless steel and aluminum alloy. How to tightly connect the inner liner - BOSS structure to address safety issues such as leakage and structural issues such as anti-rotation of type-IV hydrogen storage cylinders is one of the important problems in the structural design of type-IV hydrogen storage cylinders.

[0003] Currently, a variety of design structures for the BOSS structure have been published at home and abroad, but there are one or more problems in terms of processing and forming difficulty, structural strength, hydrogen leakage resistance, coaxiality, etc. For example: Patent 201720862795.X proposed a labyrinth seal structure, which improved the sealing effect. However, its bottle mouth structure is complex and not conducive to processing and installation; Patent US8053523B2 adopted a "boss" design structure at the head, which has a simple structure and is easy to manufacture. However, it cannot avoid relative rotation between the metal BOSS structure and the plastic inner liner; Patent 202210693138.9 adopted an internal and external thread design, which strengthened the reliability of the hydrogen system connection. However, its structure has many processing procedures and the external thread is easily damaged by bumps. Summary of the Invention

[0004] The purpose of the present invention is to disclose a BOSS structure for connecting the inner liner of a type-IV hydrogen storage cylinder, including: an external structure and an internal structure. The external structure from top to bottom is successively an installation nut, a carbon fiber winding anti-back structure, a positioning structure, a sealing ring groove, a barb boss structure, and a web inner liner connection structure; the internal structure from top to bottom is successively an inner thread for bottle valve seat connection, an inner ring groove for plastic inner liner connection, an anti-axial plastic shrinkage structure, and an inner liner anti-rotation structure.

[0005] The anti-axial plastic shrinkage structure is located at the inner hole position at the bottom of the BOSS structure and is used to prevent the axial shrinkage after the metal-plastic integral molding of the plastic inner liner; the inner liner anti-rotation structure is designed on the extended surface at the bottom of the BOSS structure, and the design dimensions are designed according to the national standard of the keyway design dimensions, with 4-8 circumferential numbers; the slope chamfer angle dimension range of the anti-axial plastic shrinkage structure is 10-85°, and the chamfer dimension range is 1-10 mm; the positioning structure is located below the carbon fiber anti-retreat structure, and the slope is consistent with the curvature of the transition surface of the head. The cross-sectional thickness dimension range of the positioning structure is preferably 5-8 mm. A barb boss structure is added at the midpoint of the original web, and a sealing ring groove is added above the transition fillet of the web. The groove depth dimension is preferably 1-4 mm, which is used for the metal-plastic integral molding process of the plastic inner liner.

[0006] The keyway depth, circumferential number and circumferential distribution center circle position of the inner liner anti-rotation structure can be adjusted according to the design requirements. When necessary, a transition fillet is milled at the bottom of the keyway.

[0007] In the external structure, the size of the mounting nut is determined by the corresponding hydrogen system bottle valve seat to be connected, and is jointly determined with reference to the overall parameters (weight, length, etc.) of the whole bottle body; the position dimension of the carbon fiber winding anti-retreat structure is designed in coordination with the pressure-bearing requirements of the hydrogen storage bottle and the diameter of the carbon fiber web; the depth of the web inner liner connection structure and the height of the ring groove are designed in coordination with the diameter of the hydrogen storage bottle cylinder, the major axis ratio and the transition ratio of the head. In the internal structure, the internal thread of the bottle valve seat connection is preferably designed with taper pipe thread, and secondly with ordinary thread design. The final design should be matched with the external thread of the bottle valve seat; the inner ring groove of the plastic inner liner connection, the inner liner anti-rotation structure and the anti-axial plastic shrinkage structure are jointly used to prevent the inner liner from shrinking and disengaging. The inner liner anti-rotation structure is preferably designed with reference to GB / T 1095-2003 "Profile Dimensions of Flat Key Keyways".

[0008] In the improved scheme, the notch shape and depth of the inner ring groove of the plastic inner liner connection can have various forms: inverted trapezoid, rhombus, and the angle range is 30-60°.

[0009] In the improved scheme, the design depth of the inner liner anti-rotation structure can be a through hole, and the blind hole design needs to be rounded at the bottom.

[0010] In the improved scheme, the slope chamfer angle dimension range of the anti-axial plastic shrinkage structure design structure is 10-85°, and the chamfer dimension range is 1-10 mm. The maximum structural thickness shall not be greater than 1 / 3 of the inner diameter of the bottle mouth. The thickness dimension needs to be matched with the keyway width of the inner liner anti-rotation structure of the keyway, and shall not be designed too large or too small, and the design deviation is within 2 mm.

[0011] In the improved solution, the cross-sectional shape of the anti-axial plastic shrinkage structure can have various forms, including but not limited to an inverted trapezoid, a triangle, a rhombus, etc.

[0012] In the improved solution, the depth of the internal thread connecting the bottle valve seat shall not be less than 1 / 3 of the overall dimension of the BOSS structure and shall not be greater than 2 / 3 of the overall dimension, and it needs to be higher than the transition fillet of the carbon fiber winding layer.

[0013] In the improved solution, for the anti-rotation structure of the inner liner, it is preferred that both ends of the structure are semicircularly transitioned with the keyway width. The alternative solution uses an elliptical or rounded chamfer transition. The length of the keyway is taken as the arc length of the design center circle. The depth of the inner liner is checked and designed according to the strength check of the BOSS structure. When designed as a blind hole groove, the bottom groove surface needs to be rounded with a radius greater than 0.5 mm to prevent difficult exhaust during the metal-plastic integral molding process of the plastic inner liner. The center circle position of the flat key of the anti-rotation structure of the inner liner should be located at the midpoint of the web, and its range can float, with the floating range being 1 / 3 to 2 / 3 of the web. In the range of 1 / 3 to 1 / 2, through holes are preferably used, and blind holes are used as alternatives; in the range of 1 / 2 to 2 / 3, blind holes are preferably used, and through holes are used as alternatives.

[0014] In the improved solution, an inclined boss structure is added at the bottom of the through hole in the BOSS structure. The slope chamfer angle dimension range of the anti-axial plastic shrinkage structure design is 10 - 85° to prevent the phenomenon of "trapped air" at the transition position during the metal-plastic integral molding process of the plastic inner liner. Among them, the cross-sectional shape of the anti-axial plastic shrinkage structure can have various forms, including but not limited to an inverted trapezoid, a triangle or a rhombus, etc.

[0015] In the improved solution, the positioning structure is below the carbon fiber anti-retreat structure, and the slope is consistent with the curvature of the head transition surface. The cross-sectional thickness dimension range of the positioning structure is preferably 5 - 8 mm. A barb boss structure is added at the midpoint of the original web, and a sealing ring groove is added above the web transition fillet. The groove depth dimension is preferably 1 - 4 mm for the metal-plastic integral molding process of the plastic inner liner.

[0016] In the improved solution, the cross-sectional shape of the barb boss structure of the BOSS structure for the inner liner of the type-IV hydrogen storage bottle can be replaced with a triangle, an inverted trapezoid or an ellipse.

[0017] In the improved solution, the BOSS structure design solution includes a BOSS structure, a sealing ring, and an inner liner. During actual use, the inner liner is subjected to internal pressure, and the force is transmitted to the sealing ring as pressure, which can make the sealing ring work effectively to prevent internal hydrogen leakage.

[0018] In the improved solution, compared with the BOSS open-end structure, the groove at the inner ring of the plastic inner liner connection is sealed, and the overall BOSS closed-end structure is preferred. As an alternative structure, a threaded plug can be used in combination with the open-end structure of the BOSS structure.

[0019] In the improved solution, the material of the BOSS structure is preferably special aluminum alloy, and the alternative is special stainless steel 316L. Both materials need to be quenched and tempered.

[0020] A BOSS structure for the inner liner of a type-IV hydrogen storage bottle according to the present invention addresses the problems of large deformation stress shrinkage caused by different material shrinkage rates during the forming process of the inner liner - BOSS and the high-pressure hydrogen storage sealing requirements of the inner liner. By gradually restricting plastic shrinkage through a circumferentially distributed structure to relieve local thermal stress, the anti-rotation structure of the inner liner is optimized. At the same time, through the synergistic effect of the barb groove and the positioning structure, the sealing effect between the inner liner and the BOSS structure is strengthened. The structure of the present invention is easy to process, the connection between the inner liner and the BOSS is more stable, local stress and strain are reduced, and the product yield is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a partial sectional view of the application of a BOSS structure for the inner liner of a type-IV hydrogen storage bottle of the present invention after forming;

[0022] Figure 2 is a sectional view of the design scheme of a BOSS structure for the inner liner of a type-IV hydrogen storage bottle of the present invention; (a) sectional view of the BOSS structure, (b) half-sectional view of the BOSS structure

[0023] Figure 3 is a partially enlarged view of the anti-rotation structure of the inner liner, (a) bottom view of the BOSS structure, (b) sectional view of the BOSS structure, (c) partially enlarged view of the anti-rotation structure;

[0024] Figure 4 is a partially enlarged view of the anti-axial plastic shrinkage structure, (a) sectional view of the BOSS structure, (b) partially enlarged view of the anti-axial plastic shrinkage structure.

[0025] Reference numerals in the figures: 1 - BOSS external structure, 2 - BOSS internal structure, 11 - mounting nut, 12 - carbon fiber winding anti-back-off structure, 13 - web inner liner connection structure, 21 - inner thread for bottle valve seat connection, 22 - inner ring groove for plastic inner liner connection, 23 - anti-rotation structure of the inner liner, 24 - anti-axial plastic shrinkage structure, 25 - overall BOSS closed-end structure, 26 - threaded plug, 31 - head transition surface, 32 - sealing ring groove, 33 - barb boss structure, 34 - positioning structure, 41 - BOSS structure, 42 - sealing ring, 43 - inner liner. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will be described in detail below with reference to the accompanying drawings.

[0027] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, terms such as "installation", "provided with", "connection", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] As a specific embodiment of the present invention, a BOSS structure for connecting the inner liner of a type-IV hydrogen storage bottle is disclosed, which can be used in the field of hydrogen energy storage and transportation. The BOSS structure for connecting the inner liner of the type-IV hydrogen storage bottle includes an external structure 1 and an internal structure 2. The specific structure is as Figure 1 shown. Among them, the external structure 1 includes a mounting nut 11, a carbon fiber winding anti-back structure 12, a positioning structure 34, a sealing ring groove 32, a barb boss structure 33, and a web inner liner connection structure 13. The size of the mounting nut 11 is determined by the connection thread of the corresponding hydrogen system bottle valve seat, and is jointly determined with reference to the overall parameters (weight, length, etc.) of the overall bottle body; the position and size of the carbon fiber winding anti-back structure 12 are designed in coordination according to the pressure-bearing requirements of the hydrogen storage bottle and the diameter of the carbon fiber web; the positioning structure 34 is below the carbon fiber anti-back structure 12, and the slope is consistent with the curvature of the transition surface of the head. The cross-sectional thickness dimension range of the positioning structure 34 is preferably 5-8 mm. A barb boss structure 33 is added at the midpoint of the original web, and a sealing ring groove 32 is added above the transition fillet of the web. The groove depth dimension is preferably 1-4 mm, which is used for the integrated metal-plastic forming process of the plastic inner liner; the depth of the web inner liner connection structure 13 and the height of the ring groove are designed in coordination according to the diameter of the hydrogen storage bottle cylinder, the major axis ratio and the transition ratio of the head.

[0029] The internal structure 2 includes an internal thread 21 for connecting the bottle valve seat, an inner ring groove 22 for connecting the plastic inner liner, an anti-rotation structure 23 for the inner liner, and an anti-axial plastic shrinkage structure 24. The internal thread 21 for connecting the bottle valve seat is preferably designed with a taper pipe thread and secondly with a common thread design. The final design should match the external thread of the bottle valve seat. The inner ring groove 22 for connecting the plastic inner liner, the anti-rotation structure 23 for the inner liner, and the anti-axial plastic shrinkage structure 24 are jointly used to prevent the inner liner from shrinking and disengaging. The anti-rotation structure 23 for the inner liner is designed with reference to GB / T 1095-2003 "Profile Dimensions of Parallel Keyways". The number of them is set to 4-8 according to needs. When necessary, a transition fillet is milled at the bottom of the keyway. The slope chamfer angle dimension range of the anti-axial plastic shrinkage structure 24 is 0-85°, and the chamfer dimension range is 1-10 mm. The specific design dimensions need to be designed in coordination with related structures (the inner ring groove 22 for connecting the plastic inner liner, the anti-rotation structure 23 for the inner liner).

[0030] The partial sectional view of the assembly of the BOSS structure - seal ring - inner liner is shown as Figure 1 follows. The figure includes a BOSS structure 41, a seal ring 42, and an inner liner 43. During actual use, the inner pressure acts inside the inner liner, and the force is transmitted to the seal ring as pressure, which can enable the seal ring 42 to work effectively to prevent internal hydrogen leakage.

[0031] As Figure 2 (a) and Figure 2 (b) show, it is a sectional view of the design scheme of the BOSS structure. A positioning structure 34 is added below the carbon fiber anti-retreat structure 12, and the curvature of the inclined surface is the same as that of the transition surface 31 of the head. The cross-sectional thickness dimension range of the positioning structure 34 is preferably 5-8 mm. A barb boss structure 33 is added at the midpoint of the original web, and a seal ring groove 32 is added above the transition fillet of the web for the metal-plastic one-piece forming process of the plastic inner liner. The cross-sectional shape of the barb boss structure 33 of the BOSS structure for the inner liner of the type IV hydrogen storage bottle can be replaced by a triangle, an inverted trapezoid, or an ellipse.

[0032] As Figure 3(a)-(c) are partial enlarged schematic diagrams of the inner liner anti-rotation structure. The inner liner anti-rotation structure 23 is preferably designed with a flat keyway. The design standard refers to GB / T 1095-2003 "Cross-sectional dimensions of flat keyways". The keyway width is used to make a semicircular transition at both ends. The length of the keyway is the arc length of the designed center circle. The depth of the inner liner is elastically designed according to the strength check of the BOSS structure. If it is designed as a blind hole groove, the bottom groove surface needs to be rounded by more than 0.5mm to prevent the difficulty of exhaust during the metal-plastic one-piece molding process of the plastic liner. The center circle position of the flat key should be located at the midpoint of the web, and its range can float, and the floating range is 1 / 3 to 2 / 3 of the web. In the range of 1 / 3 to 1 / 2, it is preferred to use a through hole, and a blind hole is an alternative; in the range of 1 / 2 to 2 / 3, a blind hole is preferred, and a through hole is an alternative.

[0033] like Figure 4 (a) and Figure 4 (b) is a partial enlarged schematic diagram of the anti-axial plastic shrinkage structure. A bevel boss structure 24 is added at the bottom of the through hole in the BOSS structure. The slope chamfer angle of the anti-axial plastic shrinkage structure is designed to be in the range of 0-85° to prevent the "air trapping" phenomenon from occurring at the transition position during the metal-plastic one-piece molding process of the plastic liner. The cross-sectional shape of the anti-axial plastic shrinkage structure can be in various forms, including but not limited to an inverted trapezoid, a triangle, a rhombus, etc.

[0034] The mounting nut 11 described in the BOSS structural cutaway diagram is used for connection and rotation with the hydrogen system. The design used is based on GB / Z 32564-2016 "Nut Design Guide". When rotating and connecting, a torque wrench or a special fixture can be used to screw in to ensure that the connection is coaxially aligned and the screw ridges and threads are not damaged by installation. The depth of the thread shall not be less than 1 / 3 of the overall size of the BOSS structure, shall not be greater than 2 / 3 of the overall size, and shall be higher than the transition fillet of the carbon fiber winding layer.

[0035] Compared with the BOSS open end structure, the BOSS closed end structure is sealed at the groove where the plastic liner is connected to the inner ring groove 22, which is the preferred BOSS closed end integral structure 25. The alternative structure can use a threaded plug 26 to cooperate with the BOSS open end structure.

[0036] In the actual production process of this patent, the specific processing technology can be adjusted according to the actual situation. This patent only protects the structural design.

Claims

1. A BOSS structure for the inner liner of a type-IV hydrogen storage cylinder, characterized in that: It includes an external structure and an internal structure. The external structure from top to bottom is successively an installation nut, a carbon fiber winding anti-back structure, a positioning structure, a sealing ring groove, an inverted hook boss structure, and a web inner liner connection structure; the internal structure from top to bottom is successively an inner thread for connecting the valve seat, an inner ring groove for connecting the plastic inner liner, an anti-axial plastic shrinkage structure, and an inner liner anti-rotation structure; the anti-axial plastic shrinkage structure is located at the inner hole position at the bottom of the BOSS structure and is used to prevent the axial shrinkage after the metal-plastic integral molding of the plastic inner liner; the inner liner anti-rotation structure is designed on the extension surface at the bottom of the BOSS structure, and the design dimensions are designed according to the national standard of the keyway design dimensions, with the circumferential number being 4-8; the slope chamfer angle dimension range of the anti-axial plastic shrinkage structure is 10-85°, and the chamfer dimension range is 1-10 mm; the positioning structure is located below the carbon fiber anti-back structure, and the slope is consistent with the curvature of the transition surface of the head. The cross-sectional thickness dimension range of the positioning structure is preferably 5-8 mm. An inverted hook boss structure is added at the midpoint of the original web, and a sealing ring groove is added above the transition fillet of the web. The groove depth dimension is preferably 1-4 mm, which is used for the metal-plastic integral molding process of the plastic inner liner.

2. The BOSS structure for the inner liner of a type-IV hydrogen storage cylinder according to claim 1, wherein: The notch shape and depth of the inner ring groove for connecting the plastic inner liner can have various forms: an inverted trapezoid or a rhombus, with the angle range being 30-60°; the slope chamfer angle dimension range of the design structure of the anti-axial plastic shrinkage structure is 10-85°, and the chamfer dimension range is 1-10 mm. The maximum size of its structural thickness shall not be greater than 1 / 3 of the inner diameter of the bottle mouth, and the thickness dimension needs to be matched with the keyway width of the keyway of the inner liner anti-rotation structure, with the design deviation within 2 mm.

3. The BOSS structure for the inner liner of a type-IV hydrogen storage cylinder according to claim 1, characterized in that: The cross-sectional shape of the anti-axial plastic shrinkage structure has various forms, including an inverted trapezoid, a triangle, or a rhombus, etc.; the depth of the inner thread for connecting the valve seat of the bottle shall not be less than 1 / 3 of the overall size of the BOSS structure, not greater than 2 / 3 of the overall size, and it needs to be higher than the transition fillet of the carbon fiber winding layer.

4. The BOSS structure for the inner liner of a type-IV hydrogen storage cylinder according to claim 1, characterized in that: For the inverted hook boss structure of the BOSS structure of the inner liner, its cross-sectional shape can be replaced with a triangle, an inverted trapezoid, or an ellipse; the groove of the inner ring groove for connecting the plastic inner liner is closed.

5. A BOSS structure for the inner liner of a type-IV hydrogen storage cylinder according to claim 1, characterized in that: The material of the BOSS structure is selected from special aluminum alloy or stainless steel 316L, and both materials need to be quenched and tempered.

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