Tubular protective sheath with knitted double wall and method of making same

Abstract

A thermal protection tubular sheath (10) includes a knitted inner wall (14b) having a circumferentially continuous outer surface (16) and an inner surface (18). The circumferentially continuous inner surface defines a cavity (20) extending longitudinally along a longitudinal central axis (22) between opposite inner ends of the knitted inner wall (14b). The tubular sheath (10) also includes a knitted outer wall (14a) having a circumferentially continuous outer surface (26) and an inner surface (28). The knitted outer wall (14a) extends longitudinally around the longitudinal central axis (22) between opposite outer ends and overlies the knitted inner wall (14b). The intermediate yarn (40) shuttles back and forth between the knitting stitches of the outer wall (14a) and the knitting stitches of the inner wall (14b), and connects the knitted outer wall (14a) and the knitted inner wall (14b) to each other.

Description

Cross-references to related applications

[0001] This PCT international patent application claims priority to U.S. Patent Application Serial No. 18 / 241,714, filed September 1, 2023, the entire contents of which are hereby incorporated herein by reference. Technical Field

[0002] The present invention generally relates to tubular protective sleeves for protecting elongated components contained therein, and more specifically to knitted tubular protective sleeves and methods for manufacturing the same. Background Technology

[0003] Single-walled tubular sheaths are known for protecting long structural members from thermal environments. These sheaths are typically made of heat-resistant yarns (such as silica, fiberglass, ceramics, basalt, aramid, or carbon fiber) to withstand high temperatures. While generally effective in providing a thermal barrier, the heat-resistant yarns forming the outer wall of the sheath are often susceptible to damage. Therefore, to provide abrasion, impact, or crush protection, an additional sheath is usually added outside the single-walled sheath via a separate process. While this approach can be effective, it is typically cumbersome, bulky, and costly. Summary of the Invention

[0004] According to one aspect of the invention, a tubular sheath is provided for providing thermal protection around an elongated member, such as a busbar in an electric vehicle battery pack. The tubular sheath includes a knitted inner wall having a circumferentially continuous outer surface and a circumferentially continuous inner surface. The circumferentially continuous inner surface defines a cavity extending longitudinally along a longitudinal central axis between opposite inner ends of the knitted inner wall. The tubular sheath also includes a knitted outer wall having a circumferentially continuous outer surface and a circumferentially continuous inner surface. The knitted outer wall extends longitudinally around a longitudinal central axis between opposite outer ends and covers the knitted inner wall. Furthermore, an intermediate yarn extends reciprocally between the knitted outer wall and the knitted inner wall, connecting the knitted outer wall and the knitted inner wall to each other.

[0005] According to another aspect of the invention, the inner wall of the knitted fabric is entirely knitted with a first yarn forming interconnected inner knitted loops; the outer wall of the knitted fabric is entirely knitted with a second yarn forming interconnected outer knitted loops, and the inner knitted loops are not knitted into the outer knitted loops.

[0006] According to another aspect of the invention, the intermediate yarn is the only connection between the inner wall and the outer wall of the knit.

[0007] According to another aspect of the invention, the intermediate yarn is knitted in a tucked weave.

[0008] According to another aspect of the invention, both the inner and outer knitted loops are formed using weft-knitted loops.

[0009] According to another aspect of the invention, the weft knitting loop is a plain knit loop.

[0010] According to another aspect of the invention, both the first yarn and the second yarn are multifilament yarns.

[0011] According to another aspect of the invention, the first yarn and the second yarn can be provided as different types of materials to optimize the desired performance properties of the inner and outer walls.

[0012] According to another aspect of the invention, the multifilament comprises at least one of glass fiber, ceramic, basalt, silica, slate, slag, aramid, and carbon fiber.

[0013] According to another aspect of the invention, the intermediate yarn is a monofilament.

[0014] According to another aspect of the invention, the monofilament is heat-set to apply bias pressure to the inner and outer walls of the knitted fabric, thereby maintaining the inner and outer walls of the knitted fabric and the cavity defined by the inner wall in a predetermined shape.

[0015] According to another aspect of the invention, the inner ends and outer ends are radially aligned and substantially flush.

[0016] According to another aspect of the invention, a method is provided for constructing a tubular textile sheath for providing thermal protection around an elongated member. The method includes: knitting an inner wall on two independent needle beds of a four-bed weft knitting machine, the inner wall having a circumferentially continuous outer surface and a circumferentially continuous inner surface, wherein the circumferentially continuous inner surface defines a cavity extending longitudinally along a longitudinal central axis between opposite inner ends of the knitted inner wall. Furthermore, on two additional independent needle beds of the four-bed weft knitting machine, different from the two independent needle beds used for knitting the inner wall, an outer wall is knitted at a position overlapping the inner wall, the outer wall having a circumferentially continuous outer surface and a circumferentially continuous inner surface, the knitted outer wall extending longitudinally around a longitudinal central axis between opposite outer ends. Additionally, an intermediate yarn is reciprocatedly knitted between the outer wall and the inner wall to connect the outer wall and the inner wall to each other.

[0017] According to another aspect of the invention, the method may further include knitting the intermediate yarn using a tuck weave.

[0018] According to another aspect of the invention, the method may further include an inner wall and an outer wall that are fully knitted using multifilament yarns.

[0019] According to another aspect of the invention, the method may further include providing multifilament yarn made of at least one material selected from glass fiber, ceramic, basalt, silica, slate, slag, aramid, and carbon fiber.

[0020] According to another aspect of the invention, the method may further include using a monofilament yarn as an intermediate yarn.

[0021] According to another aspect of the invention, the method may further include an inner wall and an outer wall fully knitted using plain knitting loops.

[0022] According to another aspect of the invention, the method may also include knitting the intermediate yarn on all four needle beds of a four-bed weft knitting machine.

[0023] According to another aspect of the invention, the method may further include shaping the inner and outer walls to form a cavity having a desired shape, followed by heat setting of the intermediate yarn to apply bias pressure to the inner and outer walls, thereby maintaining the cavity in the desired shape. Attached Figure Description

[0024] The above and other aspects, features, and advantages of the present invention will be more readily understood in conjunction with the following detailed description of the present preferred embodiments and best practices, the appended claims, and the accompanying drawings, wherein: Figure 1A A schematic perspective view of a knitted tubular sheath according to one aspect of the invention, showing an elongated tubular member to be protected extending through the knitted tubular sheath; Figure 1B This is a schematic cross-sectional view of the knitted tubular sheath taken roughly along line 1B-1B in Figure 1; Figure 1C Figure 1 shows a partial perspective view of the knitted tubular sheath; and Figure 2 For illustrative purposes, it shows yarns knitted on a four-bed weft knitting machine to form the knitted tubular sheath shown in Figure 1, the yarns forming individual tubular walls aligned axially and radially with each other, and intermediate yarns connecting the individual tubular walls to each other. Detailed Implementation

[0025] Referring more closely to the accompanying drawings, Figure 1 shows a tubular sheath 10 used to provide protection around an elongated member 12 to protect it from thermal conditions, environmental factors, abrasion, compression, and to provide dielectric protection. The sheath 10 is protective because it provides a thermal barrier (especially against extreme temperatures and flames), which is particularly important in applications such as protecting busbars 12 of adjacent batteries in interconnected electric vehicle battery packs. The sheath 10 also prevents environmental contaminants from intruding and / or damaging the sheath itself and the internal elongated member 12, such as impacts from stones, abrasive debris or surfaces, and liquid contaminants (such as fuel, oil, and water). The sheath 10 has a one-piece, single-piece tubular knitted wall 14, comprising a knitted outer wall 14a and a knitted inner wall 14b surrounded and covered by the outer wall 14a. The outer wall 14a and the inner wall 14b are knitted together in a single knitting process using a four-bed weft knitting machine 15, such as... Figure 2 As shown, the machine has a first needle bed 32a, a second needle bed 32b, a third needle bed 32c, and a fourth needle bed 32d. Therefore, the finished wall 14 is seamless, and the sheath 10 can be easily processed as a single product without a secondary stitching process to connect the outer wall 14a and the inner wall 14b. In the illustrated non-limiting embodiment, the outer wall 14a is primarily knitted on the first needle bed 32a and the fourth needle bed 32b, while the inner wall 14b is primarily knitted on the second needle bed 32b and the third needle bed 32c. A single knit stitch 34a on one side of the outer wall 14a is shown knitted on the needles of the second needle bed 32b, while a single knit stitch on the other side of the outer wall 14a is knitted on the needles of the third needle bed 32b. Otherwise, the outer wall 14a is knitted on the first needle bed 32a and the fourth needle bed 32d. In contrast, the inner wall 14b is shown knitted entirely on the second needle bed 32b and the third needle bed 32c.

[0026] like Figure 1B and Figure 2 As best shown, the knitted inner wall 14b is a seamless and circumferentially continuous structure, having an outer surface 16 and an inner surface 18. The inner surface 18 defines a cavity 20 that extends longitudinally along a longitudinal central axis 22 between the opposing inner ends 24a, 24b of the knitted inner wall 14b. The inner wall 14b is entirely knitted from a first yarn Y1, which forms interconnected internal knitted loops 36. The inner wall 14b is entirely knitted from a heat-resistant multifilament yarn capable of withstanding extreme temperature environments of approximately 60 to 1400 degrees Celsius. The selected multifilament yarn may be entirely composed of mineral fiber materials, such as silica, glass fiber, ceramics, basalt, slate, slag, aramid, or carbon fiber, as illustrative purposes only and not limiting. The mineral fibers may have a continuous or chopped fiber structure. In certain extreme high-temperature applications, the sheath material may be heat-treated to remove organic components, thereby further improving the heat resistance of the sheath 10.

[0027] The knitted outer wall 14a is a seamless and circumferentially continuous structure, having an outer surface 26 and an inner surface 28. This knitted outer wall 14a extends longitudinally around a longitudinal central axis 22 between opposite outer ends 30a and 30b, and covers the knitted inner wall 14b. The outer ends 30a and 30b are knitted to be radially aligned with the opposite inner ends 24a and 24b, appearing flush or substantially flush (i.e., no obvious difference to the naked eye, but possibly with a few millimeters of deviation). The outer wall 14b is entirely knitted using a second yarn Y2, which forms interconnected outer knitted loops 38. The second yarn can be of the same type as the first yarn, or a different type can be selected depending on the application requirements. Therefore, depending on the application requirements, the yarn used to knit the outer wall 14a can have the same or lower heat resistance as the yarn used to knit the inner wall 14b. Therefore, it is conceivable to use yarns more resistant to external debris abrasion and impact to construct the outer wall 14a, so that the sheath 10 can withstand external abrasion and debris impact through the outer wall 14a without significant damage, while also resisting extreme high temperatures and providing dielectric protection. Some yarns considered suitable for providing enhanced abrasion resistance to the outer wall 14a include: polyester, nylon, polypropylene, polyethylene, acrylic, cotton, rayon, and flame-retardant (FR) versions of the above materials, depending on the target application requirements. In addition to the above materials, if enhanced performance is required, the same mineral fiber yarns used to construct the inner wall 14b, or different mineral fiber yarns, can be considered for constructing the outer wall 14a.

[0028] During the knitting process, the outer wall 14a is integrally knitted with the inner wall 14b via an intermediate yarn 40. This intermediate yarn 40 uses a tuck weave structure, repeatedly weaving between the knitted loops of the outer wall 14a and the inner wall 14b, thereby connecting the knitted outer wall 14a and the knitted inner wall 14b. The intermediate yarn 40, extending through the loops of the outer wall 14a and the inner wall 14b, is the only connection between the outer wall 14a and the inner wall 14b, thus achieving physical coupling and preventing separation of the outer wall 14a and the inner wall 14b. Therefore, without the intermediate yarn, the outer wall 14a and the inner wall 14b would be separable. This intermediate yarn 40 can be made of monofilament yarn, which has a higher stiffness than the multifilament yarn used for the outer wall 14a and the inner wall 14b. This increased relative stiffness helps maintain the cylindrical shape of the wall 14. According to another aspect, the intermediate yarn 40 can be provided as a heat-setting yarn, so that after the wall 14 is formed into the desired cylindrical shape (whether it is a regular cylinder, a rectangular cylinder or other prismatic cylinder), the heat-setting yarn can be heat-set to apply bias pressure to the knitted outer wall 14a and inner wall 14b, so that the wall 14 maintains the desired shape and contour along its length direction and extends uniformly from one end of the wall 14 to the other end.

[0029] The type of knit stitches used to construct the outer wall 14a and inner wall 14b can be flexibly adjusted according to application requirements, but regardless of the type of knit stitches used, these stitches are formed by weft knitting. Therefore, wall 14 can be knitted using any type or combination of knit stitches (e.g., plain knit, double-knit, rib knit, etc.), allowing the outer wall 14a and inner wall 14b to be knitted using a single or multiple knit stitch types, wherein the types of knit stitches used to form the outer wall 14a and inner wall 14b can be the same or different. Furthermore, wall 14 can be made to any suitable length and diameter. It will be apparent to those skilled in the art that the diameter of the outer wall 14a is crucial, as the inner wall 14b is constrained by the inner surface 28 of the outer wall 14a.

[0030] According to another aspect of this disclosure, a method is provided for constructing a tubular sheath 10 for providing thermal protection around an elongated member 12. The method includes knitting an inner wall 14b on two independent needle beds 32b, 32c of a four-bed weft knitting machine 15. The inner wall 14b has a circumferentially continuous outer surface 16 and a circumferentially continuous inner surface 18, wherein the circumferentially continuous inner surface 18 defines a cavity 20 extending longitudinally along a longitudinal central axis 22 between opposite inner ends 24a, 24b of the knitted inner wall 14b. Furthermore, an outer wall 14a is knitted on two independent needle beds 32a, 32d of the four-bed weft knitting machine 15, different from the two independent needle beds 32b, 32c used for knitting the inner wall 14b. The outer wall 14a has a circumferentially continuous outer surface 26 and a circumferentially continuous inner surface 28, overlapping the inner wall 14b, and the knitted outer wall 14a extends longitudinally around the longitudinal central axis 22 between opposite outer ends 30a, 30b. Furthermore, the outer wall 14a and the inner wall 14b are connected to each other by reciprocating knitting of the intermediate yarn 40 between the outer wall 14a and the inner wall 14b.

[0031] Based on the above technical solutions, those skilled in the art will understand that the present invention has many possible modifications and variations. It is conceivable that all features of all claims and all embodiments can be combined with each other, as long as such combinations do not contradict each other. Therefore, it should be understood that the present invention can be implemented in a manner different from the specific description, and its scope of protection is defined by the final permitted claims.

Claims

1. A tubular sheath for providing thermal protection around an elongated member, comprising: The inner wall of the knitted fabric has a circumferentially continuous outer surface and a circumferentially continuous inner surface, the circumferentially continuous inner surface defining a cavity that extends longitudinally between opposite inner ends of the knitted inner wall along a longitudinal central axis. A knitted outer wall having a circumferentially continuous outer surface and a circumferentially continuous inner surface, the knitted outer wall extending longitudinally between opposite outer ends around the said longitudinal central axis, the knitted outer wall covering the knitted inner wall; and An intermediate yarn extends back and forth between the outer wall and the inner wall of the knitted fabric to connect the outer wall and the inner wall of the knitted fabric to each other.

2. The tubular sheath as described in claim 1, wherein, The inner wall of the knitted fabric is entirely knitted with a first yarn forming interconnected inner knitted loops, and the outer wall of the knitted fabric is entirely knitted with a second yarn forming interconnected outer knitted loops, wherein the inner knitted loops are not knitted together with the outer knitted loops.

3. The tubular sheath as described in claim 2, wherein, The intermediate yarn is the only connection between the inner wall and the outer wall of the knitted fabric.

4. The tubular sheath as described in claim 3, wherein, The intermediate yarn is knitted in a tuck stitch.

5. The tubular sheath as described in claim 4, wherein, The inner and outer knitted loops are formed using weft knitted loops.

6. The tubular sheath as described in claim 5, wherein, The weft knitting loops are plain knit loops.

7. The tubular sheath as described in claim 2, wherein, The first yarn and the second yarn are multifilament yarns.

8. The tubular sheath as described in claim 7, wherein, The first yarn and the second yarn are made of different types of materials.

9. The tubular sheath as described in claim 7, wherein, The multifilament is composed of at least one of glass fiber, ceramic, basalt, silica, slate, slag, aramid, and carbon fiber.

10. The tubular sheath as claimed in claim 7, wherein, The intermediate yarn is a monofilament.

11. The tubular sheath as claimed in claim 10, wherein, The monofilament undergoes a heat-setting process to apply bias pressure to the inner and outer walls of the knitted fabric, thereby maintaining its predetermined shape.

12. The tubular sheath as claimed in claim 1, wherein, The relative inner ends are radially aligned with the relative outer ends and are substantially flush.

13. A method of constructing a tubular sheath for providing thermal protection around an elongated member, the method comprising: The inner wall is knitted on two independent needle beds of a four-bed weft knitting machine, and the inner wall having a circumferentially continuous outer surface and a circumferentially continuous inner surface is knitted, the circumferentially continuous inner surface defining a cavity that extends longitudinally between opposite inner ends of the knitted inner wall along a longitudinal central axis. On two separate needle beds of the four-bed weft knitting machine, which are different from the two separate needle beds used for knitting the inner wall, an outer wall that overlaps with the inner wall is knitted, and the outer wall having a circumferentially continuous outer surface and a circumferentially continuous inner surface is knitted, the knitted outer wall extending longitudinally between opposite outer ends around the longitudinal central axis. as well as A middle yarn is knitted back and forth between the outer wall and the inner wall to connect the outer wall and the inner wall to each other.

14. The method of claim 13, further comprising knitting the intermediate yarn using a tuck weave.

15. The method of claim 13, further comprising fully knitting the inner wall and the outer wall using multifilament yarn.

16. The method of claim 15, further comprising providing the multifilament yarn composed of at least one selected from glass fiber, ceramic, basalt, silica, slate, slag, aramid, and carbon fiber.

17. The method of claim 15, further comprising using monofilament yarn as the intermediate yarn.

18. The method of claim 13, further comprising fully knitting the inner wall and the outer wall with plain knitting loops.

19. The method of claim 13, further comprising knitting the intermediate yarn on all four needle beds of the four-bed weft knitting machine.

20. The method of claim 13, further comprising shaping the inner wall and the outer wall to form a cavity having a desired shape, and then heat-setting the intermediate yarn to apply bias pressure to the inner wall and the outer wall, thereby maintaining the cavity in the desired shape.

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