Protective tube of electrical cable, and manufacturing method of protective tube

Abstract

To provide a protective tube of electrical cable capable of being easily installed.SOLUTION: A protective tube 1 includes: a flexible outer tube 20; a flexible inner tube 30 disposed inside the outer tube 20 and an electrical cable is placed through the inner tube; and a granular refractory material Ti filled in the space between the inner surface of the outer tube 20 and the outer surface of the inner tube 30.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a protective tube through which an electric cable is passed to protect the cable. [Background technology]

[0002] In power plants such as nuclear power plants, electric cables are sometimes covered with fire-resistant materials having fire resistance. For example, in Patent Documents 1 and 2, a cable rack in which electric cables are arranged is covered with a sheet having fire resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-089306 A [Patent Document 2] JP 2016-220408 A Summary of the Invention [Problem to be solved by the invention]

[0004] When using the above-described structure, the installer must perform the cumbersome task of fixing the cable rack to a wall or ceiling and then covering the cable rack with a sheet.

[0005] The present disclosure provides a protective tube for an electric cable that can be installed with simpler work and a method for manufacturing the protective tube. [Means for solving the problem]

[0006] (1) The protective tube proposed in this disclosure includes a flexible outer tube, a flexible inner tube that is disposed inside the outer tube and through which an electric cable is passed, and a granular fireproof material that fills the space between the inner surface of the outer tube and the outer surface of the inner tube. Since the fireproof material is granular and both the outer tube and the inner tube are flexible, this protective tube can be bent, facilitating the installation work of the protective tube.

[0007] (2) The protective tube of (1) may further include a cover assembly attached to an end of the outer tube and an end of the inner tube to close the space between the inner surface of the outer tube and the outer surface of the inner tube. This can prevent leakage of the fireproof material from the protective tube, making it easier to protect the electric cable.

[0008] (3) In the protective tube of (2), the cover assembly may have a joint portion for connecting to an adjacent protective tube, which makes it easy to connect two adjacent protective tubes.

[0009] (4) In the protective tube of (2), the cover assembly may have a first seal member that seals between the cover assembly and the end of the inner tube, thereby making it possible to prevent the fireproof material from penetrating into the inside of the inner tube.

[0010] (5) In the protective tube of (2), the lid assembly may have a second seal member that seals between the lid assembly and the end of the outer tube. This makes it possible to prevent external moisture from penetrating into the protective tube.

[0011] (6) In the protective tube of (2), the lid assembly may have a seal member sandwiched between one of the inner tube and the outer tube and the lid assembly in a direction along the center line of the protective tube, and the seal member may be made of a flexible material. This allows the tube and the lid assembly to be tightly attached to each other regardless of the tolerance of the tube length.

[0012] (7) The protective tube of (1) may further include a support member located between the inner surface of the outer tube and the outer surface of the inner tube and surrounding the outer periphery of the inner tube. The support member may be embedded in the refractory material. With this protective tube, the position of the inner tube can be maintained at an appropriate position in the outer tube by the support member.

[0013] (8) In the protective tube of (1), the difference between the outer diameter of the inner tube and the inner diameter of the outer tube may be 30% to 90% of the inner diameter of the outer tube. This makes it possible to obtain a fireproof material with a sufficient thickness.

[0014] (9) In the protective tube of (1), the inner tube may have a coating layer on its outer circumferential surface, which can prevent the infiltration of the refractory material into the inner tube.

[0015] (10) A manufacturing method of a protective tube proposed in the present disclosure includes the steps of: inserting an inner tube into an outer tube; attaching a first lid assembly to one end of the outer tube and one end of the inner tube to close a space between the inner surface of the outer tube and the outer surface of the inner tube; pouring granular fireproof material into the space from the other end of the outer tube and the other end of the inner tube; and attaching a second lid assembly to the other end of the outer tube and the other end of the inner tube to close the space. According to the protective tube obtained by this manufacturing method, since the fireproof material is granular and both the outer tube and the inner tube are flexible tubes, the protective tube can be bent, which facilitates the installation work of the protective tube.

[0016] (11) In the manufacturing method of (10), the inserting step may include a step of inserting a support member into the outer tube to be disposed between the outer surface of the inner tube and the inner surface of the outer tube. According to the protective tube obtained by this manufacturing method, the position of the inner tube can be maintained at an appropriate position in the outer tube by the support member. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a diagram showing the appearance of a protective tube proposed in the present disclosure. [Diagram 2]FIG. 2 is a cross-sectional view of the protective tube shown in FIG. [Diagram 3] 2 is a cross-sectional view showing a joint portion provided at an end portion of the protective tube shown in FIG. 1. [Figure 4A] 11A and 11B are diagrams showing examples of support members that the protective tube has. [Figure 4B] 4B is a view of the support member shown in FIG. 4A as viewed in a direction along the center line of the protective tube. [Figure 5A] 13A and 13B are diagrams illustrating another example of a support member. [Figure 5B] 5B is a view of the support member shown in FIG. 5A as viewed in a direction along the center line of the protective tube. [Figure 6A] 13A and 13B are diagrams illustrating yet another example of a support member. [Figure 6B] 6B is a view of the support member shown in FIG. 6A as viewed in a direction along the center line of the protective tube. [Figure 7] 13 is a cross-sectional view of a lid assembly having a modified conductive plate. FIG. [Figure 8] FIG. 8 is a plan view of the conductive plate shown in FIG. [Figure 9] 8A to 8C are diagrams for explaining a manufacturing method of the protective tube having the conductive plate shown in FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the protective tube proposed in the present disclosure will be described. In this specification, a protective tube 1 shown in FIG. 1 and the like will be described as an example of the embodiment.

[0019] [Outer and inner pipes] As shown in FIG. 2, the protective tube 1 has an outer tube 20 and an inner tube 30 disposed inside the outer tube 20. The inner tube 30 is supported by a support member 50 inside the outer tube 20, and the inner tube 30 and the outer tube 20 have a common center line C. When the protective tube 1 is used, an electric cable (not shown) is disposed inside the inner tube 30. The protective tube 1 protects the electric cable from external temperature changes by the action of a fireproof material (described later) filled between the outer tube 20 and the inner tube 30. The difference between the outer diameter of the inner tube 30 and the inner diameter of the outer tube 20 (D in FIG. 2) may be, for example, 30% to 90% of the inner diameter R1 of the outer tube 20. The difference between the outer diameter of the inner tube 30 and the inner diameter of the outer tube 20 may be, for example, 40% to 70% of the inner diameter R1 of the outer tube 20.

[0020] Both the outer pipe 20 and the inner pipe 30 are flexible pipes. Therefore, the outer pipe 20 and the inner pipe 30 can be bent to fit the shape of the location where the electric cable is laid. The outer pipe 20 and the inner pipe 30 have pipe bodies 21 and 31, respectively, which are composed of a metal band wound in a spiral shape around the center line C of the protective pipe 1. A part of the metal band of the outer pipe 20 (for example, the part indicated by the symbol M1 in FIG. 2) is meshed and connected to another part of the metal band located adjacently in the direction along the center line C of the protective pipe 1 (for example, the part indicated by the symbol M2 in FIG. 2). (Hereinafter, the "direction along the center line C" of the protective pipe 1 will be referred to as the center line direction.) The two adjacent parts (M1 and M2) are connected to each other so that the relative positions of the two parts are allowed to change. This allows the outer pipe 20 to be bent. Similarly, a portion of the metal band of the inner tube 30 (for example, the portion indicated by symbol N1 in FIG. 2) engages and is connected to another portion of the metal band adjacent to it in the center line direction of the protective tube 1 (for example, the portion indicated by symbol N2 in FIG. 2). The two adjacent portions (N1 and N2) are connected to each other so that the relative positions of the two adjacent portions are allowed to change, thereby allowing the inner tube 30 to be bent. The tube bodies 21 and 31 are formed of an electrically conductive material. The material of the tube bodies 21 and 31 may be, for example, iron or stainless steel.

[0021] 2, the metal band of the outer tube 20 has a first engagement portion 21a along one edge thereof and a second engagement portion 21b along the opposite edge thereof. The first engagement portion 21a is, for example, substantially U-shaped and opens toward the inside of the protective tube 1, and the second engagement portion 21b is, for example, substantially U-shaped and opens toward the outside of the protective tube 1. The first engagement portion 21a of one of two adjacent portions M1 and M2 is engaged with and connected to the second engagement portion 21b of the other portion.

[0022] 2, the outer pipe 20 may have a coating layer 22 made of resin on its outside. The coating layer 22 is formed on the entire outer circumferential surface of the spirally wound metal band. The coating layer 22 can prevent rainwater and the like from entering the inside of the outer pipe 20. The coating layer 22 can be made of, for example, polyvinyl chloride.

[0023] 2, the metal band of the inner pipe 30 has a first engagement portion 31a along one edge thereof and a second engagement portion 31b along the opposite edge thereof. Each of the first engagement portion 31a and the second engagement portion 31b is, for example, hook-shaped. The first engagement portion 31a of one of two adjacent portions N1 and N2 is engaged with and connected to the second engagement portion 21b of the other portion.

[0024] A gap S is formed between the first engagement portion 21a and the second engagement portion 21b that are meshed with each other in the outer pipe 20. Therefore, the change in the relative position of two adjacent portions M1 and M2 in the outer pipe 20 is allowed to be larger than the change in the relative position of two adjacent portions N1 and N2 in the inner pipe 30. This allows the outer pipe 20, which has a larger diameter than the inner pipe 30, to be bent sufficiently.

[0025] [Fireproof material] The space between the inner surface of the outer pipe 20 and the outer surface of the inner pipe 30 is filled with a refractory material (thermal insulating material) Ti. The refractory material Ti is, for example, granular. The granular refractory material is, for example, a refractory material having a median diameter of 200 μm or more and 4000 μm or less. The median diameter of the refractory material may be 400 μm or more. The median diameter of the refractory material may be 3000 μm or less. Any appropriate material can be used as the granular refractory material, and an example of the granular refractory material is calcium silicate. The refractory material Ti may be porous granules. The granular refractory material preferably contains an endothermic component. Since the refractory material Ti is granular, the refractory material Ti can be deformed according to the bending of the inner pipe 30 and the outer pipe 20. As a result, the protective pipe 1 can be bent, and the installation work of the protective pipe 1 can be facilitated.

[0026] The Ti refractory material may be solidified granules. For example, the Ti refractory material may be solidified into a cylindrical shape. The solidified granules may be broken by bending the outer tube 20 and the inner tube 30, and may have fluidity. In this case, the Ti refractory material may have a portion formed of solidified granules and a portion formed of granules having fluidity.

[0027] [Coating layer of inner tube] 2, the inner pipe 30 may have a coating layer 32 made of resin on its outside. The coating layer 32 is formed on the entire outer circumferential surface of the spirally wound metal strip. The coating layer 32 can prevent the granular refractory material Ti from penetrating into the inside of the inner pipe 30.

[0028] [Lid assembly] As shown in Fig. 2, the protective tube 1 has a lid assembly 40 at both ends. The lid assembly 40 is attached to the end of the outer tube 20 and the end of the inner tube 30, and closes the space filled with the Ti fireproof material between the inner surface of the outer tube 20 and the outer surface of the inner tube 30. The lid assembly 40 can prevent the Ti fireproof material from leaking from the end of the protective tube 1. An opening 41g is formed in the center of the lid assembly 40, penetrating the protective tube 1 in the direction of the centerline, and the electric cable is passed through the inside of this opening 41g.

[0029] 3, the lid assembly 40 has a lid main body 41. The lid main body 41 has an outer cylinder portion 41a fixed to the outer tube 20. An end of the outer tube 20 is fitted inside the outer cylinder portion 41a. The outer cylinder portion 41a is fixed to the end of the outer tube 20 by, for example, a nut 42 fitted to the outside of the outer tube 20. The outer cylinder portion 41a is fitted inside the nut 42, and a screw formed on the outer peripheral surface of the outer cylinder portion 41a engages with the nut 42.

[0030] In the example of the protective tube 1, as shown in FIG. 3, a seal member 43 is disposed inside the nut 42. The seal member 43 is made of a flexible material (e.g., rubber or elastomer). For example, a packing can be used as the seal member 43. When the nut 42 is tightened, the outer cylinder portion 41a approaches the nut 42. At this time, the lid assembly 40 is pressed against the end face of the outer tube 20 (the end face 23c of the end fitting 23 described later) in the center line direction of the protective tube 1. Furthermore, when the nut 42 is tightened, the seal member 43 is compressed by the outer cylinder portion 41a and the nut 42 and pressed against the outer peripheral surface of the outer tube 20. As a result, the positions of the nut 42 and the lid main body 41 in the center line direction of the protective tube 1 are firmly fixed.

[0031] When the seal member 43 is compressed by the outer tube portion 41a and the nut 42, the end of the seal member 43 enters between the end 41f of the outer tube portion 41a and the outer peripheral surface of the outer tube 20. As a result, the gap between the lid assembly 40 and the outer tube 20 is sealed by the seal member 43. The seal member 43 can prevent external moisture from penetrating into the inside of the outer tube 20 through the gap between the lid body 41 and the outer surface of the outer tube 20. In addition, when the seal member 43 is compressed by the outer tube portion 41a and the nut 42, the end of the seal member 43 may press the end of the outer peripheral portion 23d of the end fitting 23 described later against the end 41f of the outer tube portion 41a of the lid body 41.

[0032] The fixing structure of the outer tube 20 and the lid body 41 is not limited to the example of the protective tube 1. For example, a ring having a screw formed on its outer circumferential surface may be fitted onto the outside of the outer tube 20, and the lid body 41 may be engaged with the ring.

[0033] In the example of the protective tube 1, as shown in FIG. 3, an annular conductive plate 44 is disposed inside the lid body 41. The conductive plate 44 is fitted to the outside of the inner tube 30. The outer tube 20 has an end fitting 23 that covers the end face of the tube body 21. The conductive plate 44 and the end face 23c of the end fitting 23 face each other in the center line direction of the protective tube 1. When the nut 42 is tightened, the lid body 41 presses the conductive plate 44 against the end fitting 23, and they are in close contact. The conductive plate 44 is formed of a material having a higher electrical conductivity than the lid body 41, for example. Stainless steel, copper, etc. may be used as the material of the conductive plate 44. As will be described in detail later, the tube body 21 of the outer tube 20 and the tube body 31 of the inner tube 30 are electrically connected via this conductive plate 44. Note that the lid assembly 40 does not necessarily have to have the conductive plate 44. In this case, the lid body 41 may be directly attached to the end surface 23c of the end fitting 23.

[0034] 3, the lid body 41 has an inner cylindrical portion 41b. An end portion of the inner tube 30 is fitted inside the inner cylindrical portion 41b. This allows the center of the outer tube 20 and the center of the inner tube 30 to coincide with each other at the end portion of the protective tube 1.

[0035] Furthermore, the lid assembly 40 is in close contact with the end of the inner tube 30 in the center line direction of the protective tube 1. In the example of the protective tube 1, the inner tube 30 has an end fitting 33 that covers the end face of the tube body 31. The inner cylinder portion 41b has, at its end, a contact portion 41d that protrudes toward the center of the protective tube 1 and faces an end face 33d of the end fitting 33 in the center line direction of the protective tube 1. The end face 33d is located in the center line direction of the protective tube 1 with respect to the end face of the tube body 31, and is a portion that covers the end face of the inner tube 30.

[0036] In the example shown in the figure, a ring-shaped seal member 45 is disposed between the contact portion 41d and the end face 33d of the end fitting 33. This makes it possible to prevent the refractory material Ti filled between the inner pipe 30 and the outer pipe 20 from penetrating into the inside of the inner pipe 30. An O-ring, for example, can be used as the seal member 45.

[0037] Moreover, the seal member 45 is formed of a flexible material. The material of the seal member 45 is, for example, rubber or elastomer. This allows the seal member 45 to absorb the tolerance of the length of the inner tube 30 and the length of the outer tube 20, and to seal between the contact portion 41d and the end fitting 33 regardless of the tolerance.

[0038] The tube body 31 of the inner tube 30 and the tube body 21 of the outer tube 20 are electrically connected. In the example of the protective tube 1, the end fitting 23 of the outer tube 20 has a tubular portion 23a that runs along the inner surface of the tube body 21 and a flange portion 23b that is formed at the end of the tubular portion 23a and hooked onto the tube body 21, and is electrically connected to the tube body 21 at the tubular portion 23a and the flange portion 23b. In addition, the end face 23c of the end fitting 23 and the conductive plate 44 are in close contact with each other and are electrically connected. Furthermore, the end fitting 33 of the inner tube 30 has a tubular portion 33a that runs along the inner surface of the inner tube 30 and a flange portion 33b that is formed at the end of the tubular portion 33a and hooked onto the tube body 31, and is electrically connected to the tube body 31 at the tubular portion 33a and the flange portion 33b. The end fitting 33 has an outer circumferential portion 33c that covers the outer circumferential surface of the end of the inner tube 30. The end 33e of the outer circumferential portion 33c is in contact with and electrically connected to the conductive plate 44. In this manner, the pipe body 31 of the inner pipe 30 and the pipe body 21 of the outer pipe 20 are electrically connected to each other via the conductive plate 44.

[0039] Furthermore, the end 33e of the outer circumferential portion 33c of the end fitting 33 may be in contact with the inner cylindrical portion 41b of the lid body 41. In this case, the tube body 31 of the inner tube 30 is electrically connected to the tube body 21 of the outer tube 20 via the lid body 41.

[0040] The lid assembly 40 may have a joint portion 41e that connects two protective tubes 1. In the example of the protective tube 1, the joint portion 41e is formed in the lid body 41. A screw is formed on the outer peripheral surface of the joint portion 41e. The joint portion 41e is connected to the adjacent protective tube 1, for example, by using a nut 49 shown in FIG. 2, or is connected to the adjacent protective tube 1 via a connector that engages with the screw of the joint portion 41e. The structure of the joint portion 41e is not limited to the example of the protective tube 1, and for example, a screw may be formed on the inner peripheral surface of the joint portion 41e.

[0041] [Support material] As shown in FIG. 2, the protective tube 1 has a support member 50 formed of a wire arranged between the inner surface of the outer tube 20 and the outer surface of the inner tube 30. The support member 50 surrounds the outer periphery of the inner tube 30 and supports the inner tube 30 inside the outer tube 20. More specifically, the support member 50 supports the inner tube 30 so that the center line of the outer tube 20 (center line C of the protective tube 1) and the center line of the inner tube 30 coincide with each other. The wire functioning as the support member 50 is a metal wire that can deform in accordance with the bending of the inner tube 30 and the outer tube 20, and is, for example, a piano wire, a hard steel wire, a stainless steel wire, an oil tempered wire, a phosphorus bronze wire, or the like. The support member 50 is embedded in a refractory material Ti that fills the space between the inner surface of the outer tube 20 and the outer surface of the inner tube 30.

[0042] The support member 50 is a member wound around the center line C of the protective tube 1. In other words, the support member 50 is a spring. By using a spring in this manner, it is relatively easy to realize the deformation of the support member 50 in accordance with the bending of the inner tube 30 and the outer tube 20.

[0043] 4A, the support member 50 has an outer contact portion 51 (large diameter portion) in contact with the inner surface of the outer tube 20, and an inner contact portion 52 (small diameter portion) in contact with the outer surface of the inner tube 30. The outer contact portion 51 and the inner contact portion 52 can appropriately maintain the position of the inner tube 30 in the outer tube 20. In the example of the protective tube 1, each of the outer contact portion 51 and the inner contact portion 52 is a portion wound multiple times around the center line C. The inner tube 30 is disposed inside the inner contact portion 52.

[0044] 4A, the outer contact portion 51 has a larger diameter than the inner contact portion 52. Therefore, the distance L1 between the outer contact portion 51 and the center line of the inner tube 30 (the center line C of the protective tube 1) is larger than the distance L2 between the inner contact portion 52 and the center line of the inner tube 30 (the center line C of the protective tube 1). This structure of the support member 50 ensures a space on the inner surface of the outer tube 20 and the outer surface of the inner tube 30 for filling a sufficient amount of refractory material Ti.

[0045] In the example shown in the figure, the outer contact portion 51 (large diameter portion) is in contact with the inner surface of the outer tube 20 over the entire area in the center line direction of the protective tube 1. Similarly, the inner contact portion 52 (small diameter portion) is in contact with the outer surface of the inner tube 30 over the entire area in the center line direction of the protective tube 1. This makes it easier to stabilize the position of the inner tube 30 inside the outer tube 20. Unlike the example shown in the figure, the outer contact portion 51 may have a particularly large diameter at the center of the protective tube 1 in the center line direction, and may be in contact with the inner surface of the outer tube 20 only at this center portion. Also, the inner contact portion 52 may have a particularly small diameter at the center of the protective tube 1 in the center line direction, and may be in contact with the outer surface of the inner tube 30 only at this center portion.

[0046] As shown in FIG. 4B, the outer contact portion 51 and the inner contact portion 52 are connected to each other via a connecting portion 53 therebetween. The connecting portion 53 is a part of the wire material constituting the support member 50. Therefore, the outer contact portion 51 and the inner contact portion 52 are separated from each other in a direction along the wire material constituting the support member 50, in other words, in a direction in which the wire material is wound. In addition, in the example of the support member 50, the outer contact portion 51 and the inner contact portion 52 are also separated from each other in a center line direction of the protective tube 1. For this reason, the distance between the outer contact portion 51 and the inner contact portion 52 becomes large, and when the outer tube 20 is heated, for example, it is possible to suppress the transfer of heat to the inner tube 30 via the outer contact portion 51 and the inner contact portion 52.

[0047] 4A, the support member 50 has a plurality of outer contact portions 51 spaced apart in the direction of the center line of the protective tube 1. Similarly, the support member 50 has a plurality of inner contact portions 52 spaced apart in the direction of the center line of the protective tube 1. The outer contact portions 51 and the inner contact portions 52 are formed alternately and are distributed throughout the protective tube 1. Therefore, the protective tube 1 can be bent at any position while maintaining the inner tube 30 at the center of the protective tube 1.

[0048] 4A and 4B. For example, the support member 50 does not necessarily have to be a spring wound around the center line C. Even in this case, the support member 50 may have an outer contact portion 51 that is relatively far from the center line of the inner tube 30 and an inner contact portion 52 that is relatively short from the center line of the inner tube 30, and they may be spaced apart in the direction along the wire.

[0049] [Modification of the support member] 4A and 4B, the support member 50 is circular when viewed in the center line direction of the protective tube 1. The shape of the support member 50 is not limited to this. The support member 50 may be, for example, polygonal when viewed in the center line direction of the protective tube 1.

[0050] 5A and 5B are diagrams showing a support member 150 as a modified example of the support member. The support member 150 is a wire material wound around the center line C of the protective tube 1 and surrounding the outer periphery of the inner tube 30, similar to the support member 50 described above. In other words, the support member 150 is also a spring. The support member 150 is different from the support member 50 described above in that the support member 150 is triangular when viewed in the center line direction of the protective tube 1, as shown in FIG. 5B. More specifically, the support member 150 is an equilateral triangle. The support member 150 has a straight line portion 150a that forms one side of the triangle. The inner tube 30 is surrounded by three consecutive straight line portions 150a. Hereinafter, the wire material that forms one triangle (three consecutive straight line portions 150a) is referred to as a unit support portion. As shown in FIG. 5A, a plurality of unit support members (triangular portions) are lined up in the center line direction of the protective tube 1. This allows the protective tube 1 to be bent at any position while maintaining the inner tube 30 at the center of the protective tube 1.

[0051] As shown in FIG. 5B, the support member 50 has a plurality of outer contact portions 151 in contact with the inner surface of the outer tube 20 and a plurality of inner contact portions 152 in contact with the outer surface of the inner tube 30. In the example of the protective tube 1, the outer contact portion 151 is the apex of a triangle (the end of each straight portion 150a). The inner contact portion 152 is the contact point of the straight portion 150a with the outer peripheral surface of the inner tube 30, and is located between the two apexes of the triangle. Therefore, the inner contact portion 152 and the outer contact portion 151 are separated from each other in the direction along the wire material constituting the support member 150 (the extension direction of each straight portion 150a). The angle between the angular position of the outer contact portion 151 and the angular position of the inner contact portion 152 in the circumferential direction centered on the center line C of the protective tube 1 (angle θ in FIG. 5B) may be 60 degrees or less. A distance L3 between the outer contact portion 151 and the center line of the inner tube 30 (center line C of the protective tube 1) is greater than a distance L4 between the inner contact portion 152 and the center line of the inner tube 30 (center line C of the protective tube 1).

[0052] The shape of the support member when viewed in the center line direction of the protective tube 1 does not have to be triangular. The support member may be rectangular or pentagonal. In other words, the shape of the support member when viewed in the center line direction of the protective tube 1 may be polygonal. For example, when the support member is rectangular, the support member makes one revolution around the center line C of the protective tube 1 by four straight parts. In this case, the outer contact part is the end of the straight part, and the inner contact part is the contact point with the inner tube 30 at each straight part. Even if the shape of the support member is a polygon other than a triangle, the angle θ between the angular position of the outer contact part and the angular position of the inner contact part in the circumferential direction centered on the center line C of the protective tube 1 may be 60 degrees or less. For example, when the support member is rectangular, the angle θ between the angular position of the outer contact part and the angular position of the inner contact part may be 45 degrees or less.

[0053] In the support member 150, the angular positions of the multiple outer contact parts 151 are the same in the center line direction of the protective tube 1. For example, the multiple outer contact parts 151 located above the inner tube 30 are aligned linearly in the center line direction. Similarly, the multiple outer contact parts 151 located above the inner tube 30 are aligned linearly in the center line direction. The multiple outer contact parts 151 located at the 8 o'clock position with respect to the inner tube 30 (the outer contact parts 151 located at the lower left in FIG. 5B) are aligned linearly in the center line direction, and the multiple outer contact parts 151 located at the 4 o'clock position with respect to the inner tube 30 (the outer contact parts 151 located at the lower right in FIG. 5B) are also aligned linearly in the center line direction. Similarly, the multiple inner contact parts 152 are also aligned linearly in the center line direction.

[0054] Unlike the example shown in FIG. 5A and FIG. 5B, the angular positions of the multiple outer contact parts may vary in the circumferential direction around the center line C of the protective tube 1. FIG. 6A and FIG. 6B are diagrams for explaining such a configuration. As shown in FIG. 6B, the support member 250 has multiple outer contact parts 251 (251a to 251f) and multiple inner contact parts 252. In this diagram, the three outer contact parts 251a, 251b, and 251c are located at the vertices of one triangle (unit support member). The inner contact part 252 is provided between the two outer contact parts 251a and 251b, and the inner contact part 252 is also provided between the two outer contact parts 251b and 251c. The three outer contact parts 251d, 251e, and 251f are located at the vertices of the adjacent triangle (unit support member). In the adjacent triangle, an inner contact portion 252 is provided between two outer contact portions 251e and 251d, and an inner contact portion 252 is also provided between two outer contact portions 251f and 251e.

[0055] The angular position of each unit support member (triangle) is shifted by an angle θ with respect to another unit support member (triangle) located adjacently in the center line direction of the protective tube 1. In FIG. 6B, only three unit support members are shown as an example. The angle θ is, for example, an angle of 90 degrees or less. The angle θ may be 60 degrees or less. The angle θ may be 30 degrees or less.

[0056] The support member 250 may have a connecting portion 253 that connects two unit support members adjacent to each other in the center line direction of the protective tube 1. Such a connecting portion 253 may be disposed along the inner surface of the outer tube 20.

[0057] [Manufacturing method] A manufacturing method of the protective tube 1 will be described. First, the outer tube is cut to a length corresponding to the length of a plurality of protective tubes, to obtain the outer tube 20 of a length required at the site where the protective tube 1 is used. Similarly, the inner tube is cut to a length corresponding to the length of a plurality of protective tubes, to obtain the inner tube 30 of a length required at the site where the protective tube 1 is used. This cutting may be performed at a manufacturing plant for the protective tube 1, or may be performed at the site where the protective tube 1 is used. An end fitting 33 is attached to the end of the inner tube 30, and an end fitting 23 is attached to the end of the outer tube 20. Then, the inner tube 30 is inserted inside the outer tube 20 (insertion process). In addition, a support member 50 is inserted between the inner surface of the outer tube 20 and the outer surface of the inner tube 30. This supports the inner tube 30 on the center line of the outer tube 20. The insertion of the support member 50 may be performed before the insertion process of the inner tube 30, or may be performed simultaneously with the insertion process of the inner tube 30. For example, the inner tube 30 may be inserted inside the support member 50 , and the inner tube 30 and the support member 50 may be inserted together inside the outer tube 20 .

[0058] A lid assembly 40 is attached to one end of the outer pipe 20 and one end of the inner pipe 30 to close one end of the space between the outer pipe 20 and the inner pipe 30. Next, granular refractory material is poured into the space between the outer pipe 20 and the inner pipe 30 from the other end of the outer pipe 20 and the inner pipe 30. At this time, the outer pipe 20 and the inner pipe 30 are placed in a position where the other ends of the outer pipe 20 and the inner pipe 30 are on the upper side (upright position), and the refractory material Ti is poured between them.

[0059] Next, the outer pipe 20 and the inner pipe 30 are vibrated for a predetermined time, so that the Ti refractory material is spread throughout the space between them. This allows the Ti refractory material to be fully filled in the space between the outer pipe 20 and the inner pipe 30. After pouring the Ti refractory material into the space between the outer pipe 20 and the inner pipe 30, the total weight may be measured, and the measurement result may be compared with the weight obtained by calculation (the weight when the Ti refractory material is fully filled in the space). The Ti refractory material may be added to the space between the pipe 20 and the inner pipe 30 until the difference between the measurement result and the weight obtained by calculation becomes smaller than a predetermined value. The method of filling the Ti refractory material into the space between the pipe 20 and the inner pipe 30 is not limited to the example described here.

[0060] Finally, another lid assembly 40 is attached to the other end of the outer pipe 20 and the other end of the inner pipe 30. This results in one protective pipe 1. At the site of use, the two protective pipes 1 are connected to each other by utilizing the joint portion 41e formed in the lid assembly 40.

[0061] FIG. 7 is a cross-sectional view of a lid assembly 140 having a conductive plate 144 which is a modified example of the conductive plate 44. FIG. 8 is a plan view of the conductive plate 144. In these figures, the same elements as those of the lid assembly 40 described with reference to FIG. 2 etc. are given the same reference numerals. Below, differences between the lid assembly 40 described with reference to FIG. 2 etc. and the lid assembly 140 will be described. Items not described regarding the lid assembly 140 may be similar to those of the lid assembly 40. FIG. 9 is a view for explaining a manufacturing method of the protective tube 1 having the conductive plate 144 (specifically, a method of pouring in granular refractory material Ti).

[0062] As shown in FIG. 7, the conductive plate 144 has a through hole 144a formed therein, which penetrates the conductive plate 144 in the thickness direction (the direction along the center line C of the protective tube 1). The entire through hole 144a is blocked by the lid body 41. This makes it possible to prevent the refractory material Ti filled in the space between the inner tube 30 and the outer tube 20 from leaking out to the outside. In the example shown in the figure, the lid body 41 has a side surface 41h facing the space between the inner tube 30 and the outer tube 20. The through hole 144a is blocked by this side surface 41h. The entire edge of the inner surface of the through hole 144a (the edge on the left side in FIG. 7) is in contact with the side surface 41h.

[0063] As shown in Fig. 8, a plurality of through holes 144a may be formed in the conductive plate 144. The plurality of through holes 144a may be arranged at equal intervals around the center line C. In a state in which the conductive plate 144 is attached to the inner tube 30 and the outer tube 20, the plurality of through holes 144a may be arranged so as to surround the inner tube 30. In the example shown in the figure, four through holes 144a are formed. The number of through holes 144a is not limited to four, and may be, for example, less than four or more than four. The number of through holes 144a may be, for example, one.

[0064] As shown in FIG. 9, in the manufacturing process of the protective tube 1, the granular refractory material Ti can be poured into the space between the inner tube 30 and the outer tube 20 by using the through hole 144a and the funnel 90. In the example shown in the figure, the funnel 90 has a main body 90a capable of storing the refractory material Ti, and a plurality of supply pipes 90b extending downward from the main body 90a. The protective tube 1 is placed in an upright position. The supply pipes 90b are connected to the through hole 144a. The refractory material Ti stored in the main body 90a is supplied to the space between the inner tube 30 and the outer tube 20 through the supply pipes 90b. For example, by applying vibration to the outer tube 20 and the inner tube 30, the refractory material Ti in the main body 90a can be poured into the space between the outer tube 20 and the inner tube 30. As described above, the plurality of through holes 144a are arranged at equal intervals around the center line C of the protective tube 1. This allows the refractory material Ti to be evenly distributed throughout the space between the outer pipe 20 and the inner pipe 30.

[0065] In the illustrated example, four through holes 144a are formed in the conductive plate 144. The number of supply pipes 90b formed in the funnel 90 may be the same as or less than the number of through holes 144a. When the number of supply pipes 90b formed in the funnel 90 is less than the number of through holes 144a, the refractory material Ti can be evenly distributed in the space between the outer pipe 20 and the inner pipe 30 by switching the order of the through holes 144a to which the supply pipes 90b are connected.

[0066] [summary] As described above, the protective tube 1 includes a flexible outer tube 20, a flexible inner tube 30 that is placed inside the outer tube 20 and through which an electric cable is passed, and granular fire-resistant material Ti that fills the space between the inner surface of the outer tube 20 and the outer surface of the inner tube 30.

[0067] In addition, the manufacturing method of the protective tube includes the steps of: inserting the inner tube 30 into the inside of the outer tube 20; attaching a lid assembly 40 to one end of the outer tube 20 and one end of the inner tube 30 to close the space between the inner surface of the outer tube 20 and the outer surface of the inner tube 30; pouring granular refractory material Ti from the other end of the outer tube 20 and the other end of the inner tube 30 into the space between the inner surface of the outer tube 20 and the outer surface of the inner tube 30; and attaching another lid assembly 40 to the other end of the outer tube 20 and the other end of the inner tube 30 to close the space between the inner tube 30 and the outer tube 20.

[0068] In this protective tube 1 and the protective tube 1 obtained by this manufacturing method, the fireproof material Ti is granular, and both the outer tube 20 and the inner tube 30 are flexible tubes, so that it is possible to bend the protective tube 1, facilitating the installation work of the protective tube 1. For example, it is possible to run an electric cable inside the protective tube 1, and then bend the protective tube 1 to fit the location where the electric cable is to be installed, and then fix the protective tube.

[0069] It should be noted that the protective tube and the manufacturing method proposed in this disclosure are not limited to the protective tube 1 and the manufacturing method described above. Various modifications are possible.

[0070] For example, the support member disposed between the inner pipe 30 and the outer pipe 20 does not necessarily have to be a wire such as a spring. For example, spacers that define the distance between the outer surface of the inner pipe 30 and the inner surface of the outer pipe 20 may be attached to a plurality of positions on the outer surface of the inner pipe 30. [Explanation of symbols]

[0071] 1 protective tube, 20 outer tube, 21 tube body, 21a first engagement portion, 21b second engagement portion, 22 coating layer, 23 end fitting, 23a cylindrical portion, 23b flange portion, 23c end surface, 30 inner tube, 31 tube body, 31a first engagement portion, 31b second engagement portion, 32 coating layer, 33 end fitting, 33a cylindrical portion, 33b flange portion, 40-140 lid assembly, 50 support member, 41 lid body, 41a outer cylindrical portion, 41b inner cylindrical portion, 41d: contact portion, 41e: joint portion, 42 nut, 43 seal member, 44-144 conductive plate, 45 seal member, 49 nut, 50 support member, 51 outer contact portion (large diameter portion), 52 inner contact portion (small diameter portion), 53 Connecting portion, 150 support member, 150a straight portion, 151 outer contact portion, 152 inner contact portion, 250 support member, 251, 251a to 251f outer contact portions, 252: inner contact portion, C center line of protective tube, Ti refractory material.

Claims

1. A flexible outer tube and a flexible inner tube disposed inside the outer tube and through which an electric cable is passed; a granular refractory material filling the space between the inner surface of the outer tube and the outer surface of the inner tube; A protective tube having the above structure.

2. a cap assembly attached to an end of the outer tube and an end of the inner tube for closing a space between an inner surface of the outer tube and an outer surface of the inner tube. The protective tube according to claim 1 .

3. The cover assembly has a joint portion for connecting to an adjacent protective tube. The protective tube according to claim 2.

4. The lid assembly includes a first seal member that provides a seal between the lid assembly and the end of the inner tube. The protective tube according to claim 2.

5. The lid assembly includes a second seal member that seals between the lid assembly and the end of the outer tube. The protective tube according to claim 2.

6. the lid assembly further includes a seal member sandwiched between one of the inner tube and the outer tube and the lid assembly in a direction along a center line of the protective tube, The sealing member is made of a flexible material. The protective tube according to claim 2.

7. a support member located between the inner surface of the outer tube and the outer surface of the inner tube and surrounding an outer periphery of the inner tube; The support member is embedded in the refractory material. The protective tube according to claim 1 .

8. The difference between the outer diameter of the inner tube and the inner diameter of the outer tube is 30% to 90% of the inner diameter of the outer tube. The protective tube according to claim 1 .

9. The inner tube has a coating layer on its outer circumferential surface. The protective tube according to claim 1 .

10. an inserting step of inserting an inner tube into an outer tube; attaching a first lid assembly to one end of the outer tube and one end of the inner tube, the first lid assembly closing a space between an inner surface of the outer tube and an outer surface of the inner tube; pouring granular refractory material into the space from the other end of the outer tube and the other end of the inner tube; attaching a second lid assembly to the other end of the outer tube and the other end of the inner tube to close the space; A method for manufacturing a protective tube comprising the steps of:

11. The inserting step includes a step of inserting a support member into the outer tube to be disposed between an outer surface of the inner tube and an inner surface of the outer tube. A method for manufacturing the protective tube according to claim 10.

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