Process for forming a compressed gas tank

Abstract

A method is provided for braiding a plurality of carbon fiber tows around a polymeric liner for use in a compressed gas tank. The method includes the steps of providing the polymeric liner having a liner wall with a tubular shape extending circumferentially around an internal cavity between a leading end and a trailing end, connecting the leading end to the trailing end of the polymeric liner to form a continuous liner loop, pressurizing the internal cavity of the polymeric liner, braiding a first plurality of carbon fiber tows around an outer surface of the liner wall and between the leading end and the trailing end to form a first braided layer, and disconnecting the leading end from the trailing end of the polymeric liner.

Description

PROCESS FOR FORMING A COMPRESSED GAS TANKCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application 63 / 650,255 filed on May 21, 2024, the disclosure of which is hereby incorporated by reference in its entirety.FIELD OF THE INVENTION

[0002] The present invention relates to type IV pressure vessels for storing fluid and / or gas under pressure. More specifically, the present invention relates to a process for forming a type IV compressed gas tank for the storage of compressed gas.DESCRIPTION OF RELATED ART

[0003] Compressed gas tanks, such as type IV pressure vessels, for storage of compressed gas comprising polymeric liners and fiber reinforced composite shell structures have been used as reliable, highly efficient vessels.

[0004] Certain ty pe IV compressed gas tanks include an elongated polymeric liner having a plurality of successively alternating connector portions and chamber portions along a length of the polymeric liner with the connector portions generally having an outer diameter less than an outer diameter of the chamber portions.

[0005] One method of braiding a fiber reinforced composite shell around an outer surface of the polymeric liner and applying resin to the fibers is generally descnbed in U.S. Patent 10,821,657, wherein liquid resin is applied to the fibers during the braiding process but before braid is applied to the polymeric liner. Another method is described wherein resin is applied to an over-braided liner as the liner travels through a stationary' cavity.

[0006] However, certain known methods of braiding a fiber reinforced composite shell have an in-line process which includes a separate radial braider for each layer of the braided fiber reinforced composite. Further, certain in-line processes lack the flexibility to provide a variety of number of layers of braided fiber. In addition, certain known methods lack the flexibility to accommodate different lengths of pressure vessels. Also, applying liquid resin to the fibers during the braiding process might cause complications with the braiding process or introduce contaminants into the braided fiber. Other known processes include applying the liquid resinin-line to the fiber reinforced composite shell may also result in waste of liquid resin or may have insufficient penetration of the liquid resin within the braided fiber.

[0007] It is desirable to improve the manufacturing process of over-braiding a plurality of braided layers of carbon fiber tows on an elongated polymeric liner having a plurality of successively alternating connector portions and chamber portions. It is also desirable to improve a process for applying resin to the over-braided liner.SUMMARY OF THE INVENTION

[0008] According to one embodiment, there is provided a method for braiding a plurality' of carbon fiber tows around a polymeric liner for use in a compressed gas tank. The polymeric liner has a liner wall with a tubular shape which extends circumferentially around an internal cavity’ between a leading end and a trailing end. The method includes the steps of providing the polymeric liner, connecting the leading end to the trailing end of the polymeric liner to form a continuous liner loop, and pressurizing the internal cavity of the polymeric liner. The method also includes the steps of braiding a first plurality' of carbon fiber tows around an outer surface of the liner wall and between the leading end and the trailing end to form a first braided layer and disconnecting the leading end from the trailing end of the polymeric liner.

[0009] According to another embodiment, there is provided a braiding cell for braiding carbon fiber tows around a circumference of a polymeric liner for use in a compressed gas tank. The braiding cell includes a polymeric liner which has a liner wall with a tubular shape that extends circumferentially around an internal cavity between a leading end and a trailing end. The braiding cell further includes a liner coupling fixedly' coupling the leading end to the trailing end to form a continuous liner loop wherein the continuous liner loop includes a first portion, a second portion, a third portion, and a fourth portion spaced apart along the continuous liner loop. The braiding cell further includes a first wind-mill station, a second wind-mill station, a first bar puller, a first plurality' of carbon fiber tows, and a first radial braider. The first windmill station includes a first shaft, a first drive motor, and a first plurality' of arms. The first drive motor is driveably coupled to the first shaft for rotating the first shaft. Each one of the first plurality of arms has a first proximal end fixedly coupled to the first shaft and a first distal end supporting and driveably coupled to the first portion of the continuous liner loop. The second wind-mill station includes a second shaft, a second drive motor, and a second plurality' of arms. The second drive motor is driveably coupled to the second shaft for rotating the second shaft.Each one of the second plurality' of arms has a second proximal end fixedly coupled to the second shaft and a second distal end supporting and driveably coupled to the second portion of the continuous liner loop. The first bar puller is spaced between the first and second wind-mill stations. The first bar puller is spaced between the first and second wind-mill stations. Further, the first bar puller is driveably coupled to the third portion of the continuous liner loop for transposing the third portion of the continuous liner loop in a first direction towards the second wind-mill station. The first radial braider is spaced between the first bar puller and the first wind-mill station. The first radial braider is operatively coupled to the first plurality of carbon fiber tows for braiding the plurality of carbon fiber tows around a circumference of the polymeric liner to form a first braided layer.

[0010] According to another embodiment, there is provided a method for infusing liquid resin into a tank preform for use in a compressed gas tank. The method includes the step of providing a tank preform which includes a polymeric liner having a liner wall extending in a circumferential direction around an internal cavity and extending between a first tank end and a second tank end, a carbon fiber shell extending circumferentially around the polymeric liner between the first tank end and the second tank end, a first end fitting is fixedly coupled to the first tank end, a second end fitting is fixedly coupled to the second tank end, wherein the first end fitting and the second end fitting enclose the internal cavity. The method also includes the steps of pressurizing the internal cavity in the tank preform and providing an infusion vessel having an infusion cavity and an opening into the infusion cavity. The method also includes the steps of inserting the tank preform into the infusion cavity through the opening, enclosing the opening and sealing the infusion cavity, and evacuating an internal atmosphere from within the infusion cavity. The method also includes the steps of supplying a liquid resin into the evacuated infusion cavity, supplying air pressure into the infusion cavity at an elevated pressure, dwelling for a predetermined amount of time, and after dwelling for a predetermined amount of time, evacuating excess liquid resin from the infusion cavity.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

[0012] Figure 1 is a perspective view of a type IV compressed gas tank supported by tank mounts, according to one embodiment of the present invention;

[0013] Figure 2 is a cross-sectional view of a polymeric liner, according to one embodiment of the present invention;

[0014] Figure 3 is a partial cross-sectional view of portion 3 of the compressed gas tank of Figure 1;

[0015] Figure 4 is a cross-sectional view of an end portion of a pressure vessel, according to one embodiment of the present invention;

[0016] Figure 5 is a cross-sectional view of Figure 4 taken along line 5-5;

[0017] Figure 6 is an enlarged view of portion 6 of Figure 5;

[0018] Figure 7 is a side view of a braiding cell, according to one embodiment of the present invention;

[0019] Figure 8 is an enlarged view of a right side portion of Figure 7;

[0020] Figure 9 is an enlarged view of portion 9 of Figure 8;

[0021] Figure 10 is an enlarged view of a left side portion of Figure 7;

[0022] Figure 11 is an enlarged side view of portion 11 of Figure 10, illustrating a braiding process;

[0023] Figure 12 is a perspective view of a tank preform, according to one embodiment of the present invention;

[0024] Figure 13 is a cross-sectional perspective view of an infusion vessel, according to one embodiment of the present invention;

[0025] Figure 14 is a cross-sectional perspective view of the tank form of Figure 12 assembled within the infusion vessel of Figure 13 and illustrating an integrated infusion process, according to one embodiment of the present invention; and

[0026] Figure 15 is a schematic view of a curing process for curing resin on the tank preform of Figure 14, according to one embodiment of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0027] Figures 1-15 illustrate a type IV compressed gas tank 10 and a method of production thereof, according to embodiments described herein. Directional references employed or shown in the description, figures or claims, such as top, bottom, upper, lower, upward, downward, lengthwise, widthwise, left, right, and the like, are relative terms employed for ease of description and are not intended to limit the scope of the invention in any respect. Referring to the Figures, like numerals indicate like or corresponding parts throughout the several view s.

[0028] Referring to Figures 1-6. the exemplary type IV compressed gas tank 10 comprises a polymeric liner 12 which serves as a gas barrier and a pressure containment when assembled as part of the compressed gas tank 10. The polymeric liner 12 includes a liner wall 14, an internal cavity 16, a first tank end 18, and a second tank end 20. The liner wall 14 is ty pically molded and has a generally tubular shape extending circumferentially around the internal cavity 16 between the first tank end 18 and the second tank end 20 and includes a liner outer surface 21. The polymeric liner 12 also includes a plurality’ of successively alternating chamber tanks 22 and connector portions 24 extending along a longitudinal axis 26 between the first and second tank ends 18, 20.

[0029] Depicted in Figures 2 and 4, the polymeric liner 12 terminates with a first cuff portion 28 adjacent the first tank end 18 and a second cuff portion 30 adjacent the second tank end 20. Each of the first and second cuff portions 28, 30 includes a respective exterior opening 32. The connector portions 24 and the cuff portions 28, 30 typically have a smaller outer diameter than the outer diameter of the chamber tanks 22. In addition, the connector portions 24, the cuff portions 28, 30, and / or the chamber tanks 22 optionally include corrugations 34 to allow the polymeric liner 12 to be folded such that the chamber tanks 22 are disposed parallel and adjacent to each other with the connector portions 24 forming a bend 36 (Figure 3). It will be appreciated that the polymeric liner 12 might comprise any amount, size, and shape of chamber tanks 22 and connector portions 24, without altering the scope of the present invention.

[0030] Referring to Figure 3, the compressed gas tank 10 also includes a carbon fiber reinforced polymer (CFRP) laminate 38 formed on the outer surface 21 of the polymeric liner 12 which is configured to reinforce the polymeric liner 12. Depicted in Figures 3, 5, 6, and 11, the CFRP laminate 38 comprises a carbon fiber shell 40 formed by wrapping and / or braiding one or more layers 42, 44, 46, 48 of a plurality of carbon fiber tows 50 around the outer surface21 of the polymeric liner 12, to produce a tank preform 52 having a tank outer surface 53. Depicted in Figure 6. each of the plurality of carbon fiber tows 50 includes a plurality of carbon fiber filaments 54 which are gathered into a bundle. The carbon fiber tows 50 are coated with a liquid resin 56, which is heated or cured to form the CFRP laminate 38 having a hard outer shell, as further described below.

[0031] Refernng to Figures 1 and 4. the compressed gas tank 10 also includes a first end fitting 60 and a second end fitting 62 inserted into the exterior opening 32 in the first and second cuff portions 28, 30, respectively, of the polymeric liner 12. The first and second end fittings 60, 62 include a respective passageway 64 for adding and removing a fluid or a gas 66, such as hydrogen or the like, from the internal cavity 16 of the chamber tanks 22, as generally known in the art. The compressed gas tank 10 also includes a first tank mount 68 and a second tank mount 70, which are configured to support the chamber tanks 22. The first and second tank mounts 68, 70 are spaced apart along the compressed gas tank 10 and retain the chamber tanks22 in relative position with respect to one another, as is commonly known in the art. It will be appreciated that the first and second tank mounts 68, 70 are optionally coupled to the chamber tanks 22 and / or to the connector portions 24.

[0032] Figures 7-11 depict an exemplary braiding cell 72 and a method 73 for braiding the carbon fiber shell 40 around the polymeric liner 12 to form the tank preform 52. according to one embodiment of the present invention. The method 73 for braiding the carbon fiber shell 40 is alternately described hereinafter as a braiding process 73. The braiding cell 72 allows for continuous loop sty le feed for braiding multiple layers 42, 44, 46, 48 of carbon fiber tows 50 onto the polymeric liner 12 to form the carbon fiber shell 40 without having to reload the polymeric liner 12 for each braided layer 42, 44, 46, 48 of the carbon fiber tows 50. The braiding cell 72 includes a first wind-mill station 74, a second wind-mill station 75, a first bar puller 76, a second bar puller 78, a first radial braider 80, a second radial braider 82, and a plurality of idle rollers 84 spaced between a forward end 85 and a rearward end 86 of the braiding cell 72. The braiding cell 72 is configured to allow the polymeric liner 12 to be formed into a continuous liner loop 88 which might be fed through the first and second radial braiders 80, 82 a plurality7of times to form multiple layers 42, 44, 46, 48 of braided carbon fiber tows 50 on the polymeric liner 12 as part of a closed loop system. It will be appreciated that the braiding cell 72 might contain additional and / or fewer radial braiders 80, 82, bar pullers 76. 78, idle rollers 84, and the like without altering the scope of the present invention. Further, it willbe appreciated that the relative position and spacing of the radial braiders 80, 82, the bar pullers 76, 78, and the idle rollers 84 within the braiding cell 72 is adjustable to accommodate a variety of lengths, shapes, and sizes of the polymeric liners 12.

[0033] Referring to Figures 7 and 8, the first wind-mill station 74 is positioned adjacent the forward end 85 of the braiding cell 72. The first wind-mill station 74 includes a first plurality of arms 90, a first shaft 92, and a first drive motor 94. The first plurality of arms 90 are configured to support the polymeric liner 12 as the polymeric liner 12 reverses direction when being transposed along the continuous liner loop 88. The first plurality of arms 90 includes a first forward arm 90a, a second forward arm 90b, a third forward arm 90c, and a fourth forward arm 90d. Each one of the first through fourth forward arms 90a-90d has a first proximal end 96 fixedly coupled to the first shaft 92 and a first distal end 98 configured to support a first portion 88a of the polymeric liner 12 and / or the tank preform 52. The first drive motor 94 is driveably coupled to the first shaft 92, as is commonly known in the art. In operation, the first drive motor 94 rotates the first shaft 92, causing the first plurality of arms 90 to rotate in a first rotational direction 100 about the first shaft 92. It will be appreciated that the distance between the first proximal end 96 and the first distal end 98 of each one of the first through fourth forward arms 90a-90d can be adjusted to accommodate different length of chamber tanks 22 and connector portions 24 on the polymeric liner 12. For example, the length of each one of the first plurality of arms 90 can be increased and / or decreased such that the first distal ends 98 of the first through fourth forward arms 90a-90d engage and support adjacent portions of the connector portions 24 on the polymeric liner 12 as the first wind-mill station 74 transposes the polymeric liner 12.

[0034] Referring to Figure 10, the second wind-mill station 75 is positioned adjacent the rearward end 86 of the braiding cell 72. The second wind-mill station 75 includes a second plurality of arms 102, a second shaft 104, and a second drive motor 106. The second plurality of arms 102 are configured to support the polymeric liner 12 as the polymeric liner 12 reverses direction when being transposed along the loop 88. The second plurality of arms 102 includes a first rearward arm 102a, a second rearward arm 102b, a third rearward arm 102c, and a fourth rearward arm 102d. Each one of the first through fourth rearward arms 102a-102d has a second proximal end 108 fixedly coupled to the second shaft 104 and a second distal end 110 configured to support a second portion 88b of the polymeric liner 12 and / or the tank preform 52. The second drive motor 106 is driveably coupled to the second shaft 104, as is commonlyknown in the art. In operation, the second drive motor 106 rotates the second shaft 104, causing the second plurality of arms 102 to rotate in the first rotational direction 100 about the second shaft 104. It will be appreciated that the distance between the second proximal end 108 and the second distal end 110 of each one of the first through fourth rearward arms 102a-102d can be adjusted to accommodate different length of chamber tanks 22 and connector portions 24 on the polymeric liner 12. For example, the length of each one of the second plurality of arms 102 can be increased and / or decreased such that the second distal ends 108 of the first through fourth rearward arms 102a-102d engage and support adjacent portions of the connector portions 24 on the polymeric liner 12 as the second wind-mill station 75 transposes the polymeric liner 12.

[0035] During operation, the first and second wind-mill stations 74, 75 transpose the polymeric liner 12 around the loop 88. The first and second wind-mill stations 74, 75 are generally configured for a continuous bi-directional process to provide a closed loop system. Further, the first and second plurality of arms 90, 102 are conformable to support the polymeric liner 12 which might have a plurality of previously -braided layers 42, 44, 46, 48 of carbon fiber tows 50. The first and second wind-mill stations 74, 75 allow for infinite braiding of the carbon fiber tows 50 onto the polymeric liner 12. In addition, the first and second wind-mill stations 74, 75 generally rotate the first and second shafts 92, 104 to transverse the polymeric liner 12 in a single rotational direction (arrow 100) at a time around the loop 88. In Figures 7-10, the first and second wind-mill stations 74, 75 transpose the polymeric liner 12 in a clockwise direction (i.e., a first direction) around the loop 88, as illustrated by arrows 112 and 114 for the respective lower and upper halves of the loop 88. Further, the first and second wind-mill stations 74. 75 are configured to provide electronic camming and include interconnectivity of programmable elements.

[0036] Depicted in Figures 7 and 10, the first and second bar pullers 76, 78, also described as caterpillar pullers, are driveably coupled to a third portion 88c and a fourth portion 88d, respectively of the polymeric liner 12. Further, the first and second bar pullers 76, 78 are configured to transpose the polymeric liner 12 along the loop 88 in the direction of arrow 112 (i.e., a first direction). The first and second bar pullers 76, 78 are configured as commonly known in the art and are capable of varying the transverse speed of the polymeric liner 12 along the loop 88. During operation, the first and second bar pullers 76, 78 control the transverse speed of the polymeric liner 12 and vary the speed based on the required diameter and / or taperof the layer 42, 44, 46, 48 of carbon fiber tows 50 currently being braided. The second bar puller 78 is generally positioned adjacent the second wind-mill station 75 in the braiding cell 72. The first bar puller 76 is generally spaced between the second bar puller 78 and the first wind-mill station 74 in the braiding cell 72.

[0037] Referring to Figures 7-11, the first radial braider 80 and the second radial braider 82 are radial braiders used to braid fibers that function as generally known in the art with modifications as listed below. The first radial braider 80 is positioned in the braiding cell 72 between the first bar puller 76 and the first wind-mill station 74. The second radial braider 82 is positioned between the first bar puller 76 and the second bar puller 78 within the braiding cell 72. Each of the first and second radial braiders 80, 82 includes a track 115 which extends in a circumferential direction and a plurality of carriers 1 16 which travel along the track 115 during a braiding process, as is commonly known in the art. In one exemplary embodiment, the first radial braider 80 includes sixty carriers 116, which is commonly described as a 60- carrier radial braider 80. In one exemplary embodiment, the second radial braider 82 includes forty-eight earners 1 16, which is commonly described as a 48-carrier radial braider 82. It will be appreciated that the first and second radial braiders 80, 82 might contain more or fewer carriers 116 without altering the scope of the present invention. The braiding cell 72 also includes a plurality of bobbins 118 w ound with carbon fiber tows 50. The bobbins 118 are placed on a respective one of the carriers 116 on the first and second radial braiders 80, 82 to provide carbon fiber tow s 50 for braiding. Depicted in Figures 10 and 11 , the first and second radial braiders 80, 82 also include a plurality of terminal eyelets 119 and a respective guide ring 120 used to guide the carbon fiber tows 50 during the braiding process 73.

[0038] As illustrated in Figure 11 , the first and second braiders 80, 82 are configured to braid a plurality of carbon fiber tows 50 around the guide ring 120 to form a braided layer, such as the one of the braided layers 42, 44, 46, 48, onto the outer surface 21 of the polymeric liner 12. It will be appreciated that the first and second radial braiders 80, 82 might be configured to braid a second braided layer 44 (or an additional braided layer 44, 46, 48) of carbon fiber tow 50 on top of and circumferentially around a previously braided layer 42 of carbon fiber tow- 50 and / or directly around the outer surface 21 of the polymeric liner 12 w ithout altering the scope of the present invention. During operation, the first radial braider 80 braids a first plurality of carbon fiber tows 50 around the polymeric liner 12 at a braid convergence point 122 forming a first braided layer 42 as the third portion 88c of the polymeric liner 12 is pulled through thefirst radial braider 80 in the direction of arrow 112 by the first bar puller 76. Next, the second radial braider 82 braids a second plurality’ of carbon fiber tows 50 around the previously braided layer 42 on the polymeric liner 12 at a second braid convergence point 124 forming a second braided layer 44 as the fourth portion 88d of the polymeric liner 12 is pulled through the second radial braider 82 in the direction of arrow 112 by the second bar puller 78.

[0039] The first and second radial braiders 80, 82 include a first controller 126 and a second controller 127, respectively. The first and second controllers 126, 127 are configured with a method for measuring the outer diameter of the polymeric liner 12 and the previously-braided layers 42, 44, 46, 48 of the carbon fiber tows 50 as the polymeric liner 12 transverses around the continuous liner loop 88 in order to control a feedback loop to adjust braid angles in realtime as the outer diameter changes. In addition, the corrugations 34 on the polymeric liner 12 affect the effective length of the polymeric liner 12. As such, the braiding parameters and the transverse speeds of the first and second radial braiders 80, 82 are adjusted by the controllers 126, 127 to accommodate the change in effective length when braiding over corrugations 34 in comparison to the portions of the polymeric liner 12 lacking corrugations 34. The length compensation in the braiding parameters and transverse speeds is also adjusted in response to variations in the outer diameter of the polymeric liner 12 and previously braided layers 42, 44, 46, 48 of the carbon fiber tows 50, as well as the difference in outer diameter of the chamber tanks 22 in comparison to the outer diameter of the connector portions 24. In one embodiment, the first and second radial braiders 80, 82 are configured with laser micrometer based closed loop braid control 128. Further, the first and second controllers 126, 127 optionally include an inline braid angle measurement closed loop feedback 130 so that the braid angle can be adjusted on the fly to accommodate changing outer diameter of the polymeric liner 12 and previously- braided layers 42, 44, 46, 48. Also, the first and second radial braiders 80, 82 are configured for automatic speed control with optimized braiding speed and with constant rotary' speed braiding in order to minimize cycle time. In one exemplary embodiment, the first and second radial braiders 80, 82 are run at a speed having a constant revolutions per minute (RPM) near about 90% of the total available braiding speed. The first and second radial braiders 80. 82 optionally include a beam sensor 132 for laser detection of disturbance in the braiding. Further, the first and second radial braiders 80, 82 optionally include a ring detection sensor 134 and a tension variation detection 136 for monitoring the braiding of the carbon fiber tows 50. In addition, the controllers 126. 127 are optionally equipped with remote tension monitoring 138 for monitoring the tension of the carbon fiber tows 50 during braiding.

[0040] Referring to Figure 11, the first and second radial braiders 80. 82 are equipped with minimal contact on the guide rings 120 and the terminal eyelets 119 to reduce the contact area during forward braiding, reverse braiding, and when forming concentric circles. The surface treatment on the guide rings 120, the terminal eyelets 119, and other contact points includes a chrome coating, such as TOPOCROM®, a ceramic coating, and / or other surface treatment processes which control surface roughness, reduce friction, and minimize wear. In one exemplary embodiment, the contact surfaces of the guide rings 120, the terminal eyelets 119, and the like, includes a consumable material that enhances the carbon fiber tows 50 and / or the CFRP laminate 38 instead of using a non-stick material that might produce a contaminate.

[0041] Depicted in Figure 7. the braiding cell 72 optionally includes a bobbin winding station 140 for winding carbon fiber tows 50 onto the bobbins 1 18 used for the first and second radial braiders 80, 82. The bobbin winding station 140 includes a winding controller 142 which controls the winding process. The winding controller 142 includes integrated Creel tension settings and is configured to provide specific wind profiles. In addition, the bobbin winding station 140 includes a payout inspection system 144 to ensure that no rings of the carbon fiber tow 50 are formed during the braiding process 73. Further, the wound bobbins 118 are inspected for bobbin hardness.

[0042] Depicted in Figures 7, 8. and 10. the plurality of idle rollers 84 are spaced apart along the continuous liner loop 88 to support the polymeric liner 12 as the polymeric liner 12 transverses the loop 88. Some of the plurality of idle rollers 84 support the polymeric liner 12 along an upper portion of the loop 88 as the polymeric liner 12 moves in the direction of arrow 114. Further, the first and second radial braiders 80. 82 include one or more idle rollers 84 supporting the upper portion of the polymeric liner 12. The remaining idle rollers 84 are spaced apart along a lower portion of the loop 88 as the polymeric liner 12 moves in the direction of arrow 112. It will be appreciated that the number and positioning of the plurality of idle rollers 84 might vary without altering the scope of the present invention.

[0043] Depicted in Figures 8, 10, and 11, the braiding cell 72 further includes a plurality' of encoders 146, with a respective encoder 146 placed adjacent to each of the first and second radial braiders 80, 82, the first and second wind-mill stations 74, 75, and the first and second bar pullers 76. 78 to facilitate registration of the polymeric liner 12 and previously-braided layers 42, 44, 46, 48 of carbon fiber tow 50 in reference to a braid convergence point 122, 124 of the first and second radial braiders 80, 82. Depicted in Figure 7, the braiding cell 72 alsoincludes an automatic payout system 148 which is configured to load the polymeric liner 12 from a liner reel (not shown) into the braiding cell 72.

[0044] An exemplary braiding process 73 is described below, according to one embodiment of the present invention. Referring to Figures 7-11, prior to initiating the braiding process 73, the spacing of the first and second radial braiders 80. 82. the first and second bar pullers 76, 78, the first and second wind-mill stations 74. 75. and the plurality of idle rollers 84 is optionally adjusted to accommodate the length, size, and shape of the polymeric liner 12 for the desired tank preform 52. It will be appreciated that the spacing may be increased or decreased to lengthen or shorten the continuous liner loop 88 as needed. Further, the length of the first and second plurality of arms 90, 102 is adjusted to correspond to the length of the chamber tanks 22 and the connector portions 24 such that each arm 90, 102 engages and supports the connector portions 24 as the polymeric liner 12 is transposed around the continuous liner loop 88.

[0045] The braiding process 73 is initiated by the automatic payout system 148 loading the polymeric liner 12 into the braiding cell 72 from a liner reel (not shown). The polymeric liner 12 includes a head end 150 opposing a tail end 151, an initial chamber tank 22a adjacent the head end 150, and a final chamber tank 22b adjacent the tail end 151. As the polymeric liner 12 is loaded into the braiding cell 72, the number of chamber tanks 22 are counted to assure the correct number of chamber tanks 22 are included. Referring to Figure 7. to form a continuous liner loop 88 of polymeric liner 12 in the braiding cell 72, the head end 150 of the polymeric liner 12 is extended through the plurality' of idle rollers 84 along the lower portion of the loop 88, through the first radial braider 80. through the first bar puller 76, through the second radial braider 82. and through the second bar puller 78. Next, the polymeric liner 12 is wrapped around the second plurality of arms 102 on the second wind-mill station 75. Next, the polymeric liner 12 is passed through the idle rollers 84 on the upper portion of the loop 88 and wrapped around the first plurality' of arms 90 on the first wind-mill station 74.

[0046] Referring to Figures 8 and 9, the head end 150 of the polymeric liner 12 is adjacent the tail end 151 after loading the polymeric liner 12 into the braiding cell 72. Next, the head end 150 is connected to the tail end 151 of the polymeric liner 12 to form the continuous liner loop 88. In order to connect the head end 150 to the tail end 151, the initial chamber tank 22a and the final chamber tank 22b are radially cut in half, forming a leading end 152 and a trailing end 153, respectively, of the polymeric liner 12. Next, a liner coupling 154 is attached to thepolymeric liner 12 and couples the leading end 152 to the trailing end 153 to form the continuous liner loop 88.

[0047] In more detail, the liner coupling 154 includes a coupling wall 155, a top side 156, a bottom side 158, an aperture 160, and a coupling fitting 161. The coupling wall 155 is generally cylindrically -shaped and extends between the top side 156 and the bottom side 158. The aperture 160 extends axially through the liner coupling 154 between the top side 156 and the bottom side 158. The coupler fitting 161 is attached to the coupling wall 155 and is fluidically connected to the aperture 160. The coupler fitting 161 is configured to transfer a fluid and / or a gas into and out of the aperture 160. Next, the leading end 152 and the trailing end 153 of the polymeric liner 12 are inserted into the aperture 160 in the top side 156 and the bottom side 158, respectively, in the liner coupling 154. The liner coupling 154 is fixedly coupled to the leading and trailing ends 152, 153 of the polymeric liner 12 to form the continuous liner loop 88. After the liner coupling 154 is attached to the polymeric liner 12, the polymeric liner 12 is pressurized via the coupler fitting 161 in the liner coupling 154 at a pressure level above atmospheric pressure.

[0048] Referring to Figures 7-11, after pressurization of the polymeric liner 12, the liner coupling 154 is positioned so that one of the first and second radial braiders 80, 82 will initiate the braiding of the first layer 42 of the carbon fiber tows 50 at the liner coupling 154. As the braiding is initiated by the one of the first and second radial braiders 80, 82, the first and second bar pullers 76, 78 and the first and second wind-mill stations 74, 75 transpose the polymeric liner 12 around the continuous liner loop 88 in the clockwise direction, as illustrated by arrows 112, 114.

[0049] In one exemplary' embodiment, the first radial braider 80 braids an initial layer 42 of braided carbon fiber tows 50 around the outer surface 21 of the bare polymeric liner 12 as the first bar puller 76 pulls the polymeric liner 12 through the first radial braider 80 in the direction of arrow 112. Next, the second bar puller 78 pulls the polymeric liner 12 through the second radial braider 82 in the direction of arrow 112. As the liner coupling 154 is pulled through the second radial braider 82 by the second bar puller 78, the second radial braider 82 braids a second layer 44 of braided carbon fiber tows 50 on top of the first braided layer 42. Next, the polymeric liner 12 passes through the second bar puller 78. Next, the second wind-mill station 75 transposes the polymeric liner 12 from the lower half of the loop 88 to the upper half of the loop 88, which allows the polymeric liner 12 to be transposed in the direction of arrow 114.Next, the polymeric liner 12 is transposed in the direction of arrow 114 through a plurality of idle rollers 84 to the first wind-mill station 74. The first wind-mill station 74 transposes the polymeric liner 12 to the lower half of the loop 88 so that the polymeric liner 12 might be transposed in the direction of arrow 112. Next, the polymeric liner 12 is transposed through additional idle rollers 84 in the direction of arrow 112 by the first bar puller 76 pulling the polymeric liner 12 to the first radial braider 80 to complete the loop 88. The polymeric liner 12 is transposed around the loop 88 multiple times to accumulate the desired number of braided layers 42, 44, 46, 48 of carbon fiber tows 50 on the polymeric liner 12 to form the carbon fiber shell 40 for the specified tank size. The braiding process 73 is terminated after the desired number of braided layers 42, 44, 46, 48 have accumulated on the polymeric liner 12 to form the tank preform 52. After the braiding process 73 is terminated, the internal cavity 16 in the polymeric liner 12 is depressurized, the liner coupling 154 decoupled from the tank preform 52, and the tank preform 52 is removed from the braiding cell 72.

[0050] A process to form the compressed gas tank 10 from the tank preform 52 is described below in reference to Figures 12-15. To form the compressed gas tank 10, the tank preform 52 is folded into a desired stacking pattern, supported by the first and second tank mounts 68, 70, and the carbon fiber shell 40 is coated with the liquid resin 56 which is hardened or cured to form a hard outer composite shell of the CFRP laminate 38. as further described below. It will be appreciated that the tank preform 52 might be folded into alternate stacking patterns without altering the scope of the present invention.

[0051] Referring to Figure 12, the first and second tank mounts 68, 70 are inserted into an assembly jig 166. Next, the tank preform 52 is loaded into the assembly jig 166, chamber tank 22 by chamber tank 22, to form a desired stacking pattern for the compressed gas tank 10. The first and second tank mounts 68, 70 are fixedly coupled to each other and / or to the tank preform 52. Next, locations for installation of the first and second end fittings 60, 62 are determined and the tank preform 52 is cut at the identified locations. Next, the first and second end fittings 60, 62 are inserted into the respective exterior openings 32 in the tank preform 52. In one exemplary embodiment, the first and second end fittings 60, 62 include a respective ferrule 168, which extends along the outer surface 53 of the tank preform 52, as is commonly known in the art. The first and second end fittings 60, 62 and the ferrules 168 are crimped to the tank preform 52 with multiple crimps to account for the spring back effect. In certain embodiments, liquid resin 56 is manually applied to the tank preform 52 to wet out the carbon fiber tows 50while the tank preform 52 is in the assembly jig 166. A syringe of liquid resin 56 is optionally used to apply and / or inject liquid resin 56 into the braided carbon fiber tows 50 to ensure that the liquid resin 56 has saturated the carbon fiber tows 50. In other embodiments, the manual application of liquid resin 56 is omitted while the tank preform 52 is in the assembly jig 166.

[0052] After the first and second end fittings 68. 70 are attached to the tank preform 52, the tank preform 52 is removed from the assembly jig 166. Next, the tank preform 52 is infused with liquid resin 56 via an integrated infusion process 170, depicted in Figure 14. The integrated infusion process 170 is alternately described as a method 170 for infusing liquid resin 56. Referring to Figures 12-14, the integrated infusion process 170 allows for moldless molding using an infusion vessel 172. The infusion vessel 172 includes an infusion cavity 174 with a near net shape to the tank preform 52. Further, the infusion cavity 174 is configurable through the addition of one or more tooling inserts 176 in order to support and contain a variety of tank preforms 52 having different shapes. The infusion vessel 172 reduces the number of different components required to produce a variety of compressed gas tanks 10 since the infusion cavity 174 can be adjusted with the tooling inserts 176.

[0053] Further, the integrated infusion process 170 allow s for infusion of the liquid resin 56 using a controlled atmosphere. Depicted in Figures 13 and 14. the infusion vessel 172 includes a chamber wall 178. a base flange 180. a top flange 182, a top opening 184, a base opening 186, a top groove 188, a first seal 190, a base groove 192, a second seal 194, a base plate 196, a plurality of support brackets 198, and a top plate 200. The chamber wall 178 extends circumferentially around the infusion cavity 174 and extends axially between the base flange 180 and the top flange 182. The base flange 180 and the top flange 182 extend radially away from and circumferentially around the chamber wall 178. The top opening 184 and the base opening 186 extend axially through the top flange 182 and the base flange 180, respectively, and adjoin the infusion cavity 174. The top groove 188 is formed in an upper surface of the top flange 182 and extends circumferentially around the top opening 184. The first seal 190 is inserted into the top groove 188. Further, the base groove 192 is formed in a lower surface of the base flange 180 and extends circumferentially around the base opening 186. The second seal 194 is inserted into the base groove 192. The base plate 196 is fixedly coupled to the base flange 180, abuts the second seal 194, and encloses the base opening 186. The plurality of support brackets 198 are axially spaced apart and fixedly coupled to an exterior surface of the chamber wall 17 . Further, the plurality of support brackets 198 extend radially away from thechamber wall 178 and extend at least partially around the chamber wall 178 in a circumferential direction. The top plate 200 is fixedly coupled to the upper surface of the top flange 182, abuts the first seal 190, and encloses the top opening 184.

[0054] The infusion vessel 172 also includes a vacuum port 202, a pressure port 204, an input port 206, and an exit port 208. The vacuum port 202 and the pressure port 204 are circumferentially spaced apart and extend through the chamber wall 178 into the infusion cavity 174 adjacent the top flange 182. The input port 206 and the exit port 208 are circumferentially spaced apart and extend through the chamber wall 178 into the infusion cavity 174 adjacent the base flange 180. In one exemplary embodiment, the vacuum port 202 and the pressure port 204 are positioned above the input port 206 and the exit port 208.

[0055] Referring to Figure 14, the infusion process 170 is initiated by inserting the tank preform 52 into the infusion cavity 174 within the infusion vessel 172. After the tank preform 52 is inserted into the infusion cavity 174. the internal cavity 16 of the tank preform 52 is pressurized to improve stability during the infusion process 170 and to consolidate the carbon fiber shell 40. It will be appreciated that the tank preform 52 is optionally pressurized prior to inserting the tank preform 52 into the infusion cavity 174. In one exemplary embodiment, the internal cavity 16 is pressurized to about 100 PSI (about 690 kPa). It will be appreciated that the amount of internal pressurization within the internal cavity 16 can vary without altering the scope of the present invention. Next, a first terminal fitting 210 and a second terminal fitting 212 are connected to the first and second end fittings 60, 62, respectively. After the first and second terminal fittings 210, 212 are connected, the base plate 196 and the top plate 200 are fixedly coupled to the base flange 180 and the top flange 182. respectively, to enclose and seal the infusion cavity 174.

[0056] After the infusion cavity 174 is sealed, vacuum is drawn from the vacuum port 202 which evacuates the internal atmosphere 214 within the infusion cavity 174. as illustrated by arrow 216. After the infusion cavity 174 is evacuated through the vacuum port 202, liquid resin 56 is pushed or supplied into the evacuated infusion cavity 174 through the input port 206 by atmospheric pressure, as illustrated by arrow 218.

[0057] After the liquid resin 56 is pushed into the infusion cavity 174, air pressure is supplied to the infusion cavity 174 through the pressure port 204 at an elevated pressure of about 60 PSI (about 414 kPa), as illustrated by arrow 220. It will be appreciated that the amount of airpressure might vary without altering the scope of the present invention. Next, the infusion process 170 is dwelled for a predetermined amount of time with the liquid resin 56 in the infusion cavity 174 under about 60 PSI (about 414 kPa) of pressure to allow the liquid resin 56 to coat the carbon fiber tows 50 within the braided layers 42, 44, 46, 48 of the carbon fiber shell 40 and to consolidate the braided layers 42, 44, 46, 48 and the resin 56 into the CFRP laminate 38.

[0058] After the dwell time has past, the excess liquid resin 56 is evacuated through the exit port 208 by the air pressure within the infusion cavity 174, as illustrated by arrow 222. After the extra liquid resin 56 is removed from the infusion cavity 174, the infusion cavity 174 is unsealed. After unsealing and opening the infusion cavity. 174, the infused tank preform 52 coated in liquid resin 56 is removed from the infusion vessel 172 while the internal pressure within the tank preform 52 is maintained.

[0059] Next, the infused tank preform 52 is cured to form the compressed gas tank 10 using a closed loop resin 56 curing process 223 depicted in Figure 15. The curing process 223 includes a curing jig 224, a rotisserie 226, and an oven 227. The curing jig 224 is configured to support the infused tank preform 52 during the curing process 223. The rotisserie 226 is configured to support a plurality of curing jigs 224 so that a plurality of infused tank preforms 52 may be cured at the same time. In addition, the rotissene 226 is configured to rotate the plurality of curing jigs 224 about a rotational axis 228, as illustrated by arrow 230. It will be appreciated that the rotational axis 228 might extend in a horizontal direction, a vertical direction, or another direction, without altering the scope of the present invention.

[0060] The rotisserie 226 is positioned within the oven 227. The oven 227 provides an elevated ambient temperature to cure the resin 56. To cure the infused tank preform 52, the infused tank preform 52 is loaded into the curing jig 224, attached to the rotisserie 226, and placed in the oven 227. Next, the temperature and time period for the curing process 223 is selected based on the viscosity profile of the resin 56. The ambient temperature in the oven 227 is maintained at the selected temperature during the curing process 223. The curing jig 224 is rotated constantly on the rotisserie 226 about the rotational axis 228 throughout a cure cycle to cure the resin 56. The pressurized infused tank preform 52 is evaluated during the curing process 223 to determine if there are any leaks via an in situ leak drop check. The curing process 223 cures the resin 56 in the infused tank preform 52, which changes the infused tank preform 52 into the compressed gas tank 10 having the hard outer shell. After the resin 56 is cured andthe time period has passed, the compressed gas tank 10 is removed from the curing jig 224 and the internal pressure within the compressed gas tank 10 is evacuated. The compressed gas tank 10 is also visually tested and proof tested. During proof testing, an inert gas is supplied to the internal cavity 16 of the compressed gas tank 10 at an elevated internal pressure to check for leaks. Next, the inert gas within the internal cavity 16 is purged from the compressed gas tank 10.

[0061] As discussed above, the process for forming a compressed gas tank 10 of the present invention includes a braiding process 73 using a braiding cell 72 and / or an integrated infusion process 170 using an infusion vessel 172. The braiding cell 72 allows for continuous loop style feeding for braiding multiple layers 42, 44, 46 48 of carbon fiber tows 50 around a polymeric liner 12 that has been formed into a continuous liner loop 88. The braiding cell 72 includes first and second wind-mill stations 74, 75, first and second bar pullers 76, 78, first and second radial braiders 80, 82, and a plurality' of idle rollers 84. Further, the braiding process 73 using the braiding cell 72 improves the manufacturing process of over-braiding a plurality of braided layers 42, 44, 46, 48 of carbon fiber tows 50 on an elongated polymeric liner 12 having a plurality of successively alternating connector portions 24 and chamber tanks 22 since the braiding process 73 allows continuous feeding of the liner loop 88 through the radial braiders 80, 82.

[0062] In addition, the integrated infusion process 170 is an improved process for applying liquid resin 56 to the over-braided liner 12. The integrated infusion process 170 allows for moldless molding using the infusion vessel 170. The infusion vessel 170 includes an infusion cavity 174 which is configurable through the addition of one or more tooling inserts 176. The infusion vessel 170 reduces the number of different components required to produce a variety of different shaped and sized compressed gas tanks 10 since the infusion cavity 176 can be adjusted using tool inserts 176. Further, the infusion vessel 170 allows for infusion of the liquid resin 56 using a controlled atmosphere during the integrated infusion process 170.

[0063] The invention has been described in an illustrative manner, and it is to be understood that the terminology', which has been used, is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described.

Claims

What is claimed is:

1. A method for braiding a plurality of carbon fiber tows around a polymeric liner for use in a compressed gas tank, the method comprising: providing the polymeric liner, the polymeric liner including a liner wall having a tubular shape and extending circumferentially around an internal cavity between a leading end and a trailing end; connecting the leading end to the trailing end of the polymeric liner to form a continuous liner loop; pressurizing the internal cavity of the polymeric liner; braiding a first plurality7of carbon fiber tows around an outer surface of the liner wall and between the leading end and the trailing end to form a first braided layer: and disconnecting the leading end from the trailing end of the polymeric liner.

2. The method as set forth in claim 1, wherein connecting the leading end to the trailing end of the polymeric liner to form the continuous liner loop further comprises: providing a liner coupling including a coupling wall which is cylindrically-shaped and extends between a top side and a bottom side and including an aperture extending between the top side and the bottom side; connecting the leading end to the liner coupling by inserting the leading end through the top side and into the aperture; and connecting the trailing end to the liner coupling by inserting the trailing end through the bottom side and into the aperture.

3. The method as set forth in claim 2, wherein: the liner coupling further comprises a coupling fitting fluidically connected to the aperture; and pressurizing the internal cavity of the polymeric liner further comprises supplying a fluid or a gas through the coupling fitting and into the aperture.

4. The method as set forth in any one of claims 1 to 3, further comprising: braiding a second plurality of carbon fiber tow s on top of and circumferentially around the first braided layer between the leading end and the trailing end to form a second braided layer prior to disconnecting the leading end from the trailing end of the polymeric liner.

5. The method as set forth in claim 4, further comprising:transposing the continuous liner loop in a first rotational direction while braiding the first plurality of carbon fiber tows around the outer surface of the liner wall.

6. The method as set forth in claim 5, further comprising: transposing the continuous liner loop in the first rotational direction while braiding the second plurality of carbon fiber tows on top of and circumferentially around the first braided layer.

7. A braiding cell for braiding carbon fiber tows around a circumference of a polymeric liner for use in a compressed gas tank, the braiding cell comprising: the polymeric liner including a liner wall having a tubular shape extending circumferentially around an internal canty between a leading end and a trailing end; a liner coupling fixedly coupling the leading end to the trailing end to form a continuous liner loop, the continuous liner loop comprising a first portion, a second portion, a third portion, and a fourth portion spaced apart along the continuous liner loop; a first wind-mill station comprising a first shaft, a first drive motor, and a first plurality of arms, the first drive motor driveably coupled to the first shaft for rotating the first shaft, each one of the first plurality' of arms including a first proximal end fixedly coupled to the first shaft and a first distal end supporting and driveably coupled to the first portion of the continuous liner loop; a second wind-mill station comprising a second shaft, a second drive motor, and a second plurality of arms, the second drive motor driveably coupled to the second shaft for rotating the second shaft, each one of the second plurality of arms including a second proximal end fixedly coupled to the second shaft and a second distal end supporting and driveably coupled to the second portion of the continuous liner loop; a first bar puller spaced between the first and second wind-mill stations and driveably coupled to the third portion of the continuous liner loop for transposing the third portion of the continuous liner loop in a first direction towards the second wind-mill station; a first plurality of carbon fiber tows; and a first radial braider spaced between the first bar puller and the first wind-mill station and operatively coupled to the first plurality of carbon fiber tows for braiding the first plurality of carbon fiber tows around the circumference of the polymeric liner to form a first braided layer.

8. The braiding cell as set forth in claim 7, further comprising:a second bar puller spaced between the first bar puller and the second wind-mill station and driveably coupled to the fourth portion of the continuous liner loop for transposing the fourth portion of the continuous liner loop in the first direction towards the second wind-mill station; a second plurality of carbon fiber tows; and a second radial braider spaced between the first bar puller and the second bar puller and operatively coupled to the second plurality of carbon fiber tows for braiding the second plurality of carbon fiber tows around the circumference of the polymeric liner to form a second braided layer on top of the first braided layer.

9. The braiding cell as set forth in claim 8, further comprising: a plurality of idle rollers spaced between the first and second wind-mill stations, the plurality of idle rollers supporting and driveably coupled to the continuous liner loop.

10. The braiding cell as set forth in any one of claims 7-9. further comprising: a plurality of encoders spaced between the first and second wind-mill stations to facilitate registration of the continuous liner loop.

11. A method for infusing liquid resin into a tank preform for use in a compressed gas tank, the method comprising: providing the tank preform comprising a polymeric liner including a liner wall extending in a circumferential direction around an internal cavity and extending between a first tank end and a second tank end, a carbon fiber shell extending circumferentially around the polymeric liner between the first tank end and the second tank end, a first end fitting is fixedly coupled to the first tank end, a second end fitting is fixedly coupled to the second tank end, wherein the first end fitting and the second end fitting enclose the internal cavity; pressurizing the internal cavity in the tank preform; providing an infusion vessel having an infusion cavity and an opening into the infusion cavity; inserting the tank preform into the infusion cavity through the opening; enclosing the opening and sealing the infusion cavity; evacuating an internal atmosphere from within the infusion cavity; supplying a liquid resin into the evacuated infusion cavity; supplying an air pressure into the infusion cavity at an elevated pressure; dwelling for a predetermined amount of time; andafter dwelling for the predetermined amount of time, evacuating excess liquid resin from the infusion cavity.

12. The method as set forth in claim 11, wherein: pressurizing the internal cavity in the tank preform further comprises pressurizing the internal cavity to at least 100 PSI (690 kPa); or supplying air pressure to the infusion cavity at the elevated pressure further comprises supplying the air pressure into the infusion cavity at the elevated pressure of at least 60 PSI (414 kPa).

13. The method of claim 12. the infusion vessel further comprising a chamber wall extending in the circumferential direction around the infusion cavity and between a top flange and a base flange, a vacuum port and a pressure port extending through the chamber wall which are circumferentially spaced apart and adjacent the top flange, an input port and an exit port extending through the chamber wall which are circumferentially spaced apart and adjacent the base flange; wherein evacuating the internal atmosphere within the infusion cavity further comprising evacuating the internal atmosphere through the vacuum port; or wherein supplying the liquid resin into the evacuated infusion cavity further comprising supplying the liquid resin through the input port; or wherein supplying air pressure to the infusion cavity further comprising supplying the air pressure through the pressure port; or wherein evacuating the excess liquid resin from the infusion cavity further comprising evacuating the excess liquid resin through the exit port.

14. The method as set forth in any one of claims 11 to 13, further comprising: unsealing the infusion cavity; and removing the infused tank preform from the infusion cavity.

15. The method as set forth in claim 14, further comprising: curing the liquid resin to form a hard outer shell.

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