Pipe structure

Abstract

To facilitate assembly of an inner pipe to another member in a pipe structure in which the inner pipe and an outer pipe are formed separately.SOLUTION: A double pipe 1 includes: an inner pipe 10 having a main passage 30 therein; and an outer pipe 20 disposed at an outer periphery of the inner pipe 10 and forming a sub passage 40 with the inner pipe 10. An end of the inner pipe 10 and an end of the outer pipe 20 are provided with separate fixing parts (fixing parts 12, 13 and flange parts 27b, 25) for fixing the ends to an engine 3 and a partition wall 4. The outer tube 20 has an expansion / contraction part 22 which may expand or contract in a length direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a piping structure. [Background technology]

[0002] Ships are provided with fuel piping that connects fuel tanks to internal combustion engines (for example, main engines or generator engines), and fuel is supplied from the fuel tanks to the internal combustion engines via this fuel piping. When using low-flammability fuels such as liquefied natural gas (LNG) or methanol as fuel, it is mandatory to cover the piping with a duct or the like to prevent fuel from leaking inside the ship even if the piping is damaged.

[0003] For example, Patent Document 1 listed below discloses a fuel piping structure for a ship as shown in Fig. 5. This ship is equipped with a fuel tank 130, a main engine 121 as an internal combustion engine 120, and a generator engine 122, which are connected via a first pipe 151 and a second pipe 152. The first pipe 151 extends downward via a fuel supply device 135 (e.g., a pump) adjacent to the fuel tank 130, bends at its lower end, extends horizontally, and is connected to a bulkhead 142 that defines an engine room 110. An upper portion of the first pipe 151 is covered with a duct D, and a lower portion of the first pipe 151 is disposed within a watertight compartment S or a valve room 140. As a result, even if the first pipe 151 is damaged, fuel is contained within the duct D or the valve room 140, and the fuel will not leak into the ship (e.g., the engine room 110).

[0004] On the other hand, the second pipe 152 is provided between the bulkhead 142 of the engine room 110 and the internal combustion engine 120, and connects the fuel passage in the first pipe 151 connected to the bulkhead 142 with the fuel passage provided inside the internal combustion engine 120. Because the second pipe 152 is provided in the narrow space between the internal combustion engine 120 and the bulkhead 142, it is difficult to cover it with a duct or the like. Therefore, a double pipe having an inner pipe 153 and an outer pipe 154 is provided as the second pipe 152. As a result, even if the inner pipe 153 of the second pipe 152 is damaged, the fuel is discharged into a ventilation space (not shown) through the space between the inner pipe 153 and the outer pipe 154, thereby preventing the fuel from leaking into the engine room 2.

[0005] Furthermore, Patent Document 2 listed below shows a double pipe in which the ends of an inner pipe and an outer pipe are fixed to a common flange by welding. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-160949 [Patent Document 2] JP 2016-88200 A Summary of the Invention [Problem to be solved by the invention]

[0007] The pressure of the fuel in the piping connecting the fuel tank and the internal combustion engine varies depending on the type of fuel and injection method used in the internal combustion engine, and therefore the pressure required for the piping and the appropriate structure also vary. For example, in the double piping (second piping 152) provided in the fuel piping structure of Figure 5, if the fuel pressure is high, it may be necessary to make the sealing structure of the inner pipe, through which the fuel mainly passes, different from that of the outer pipe. However, when the ends of the inner pipe and outer pipe of the double piping are welded to flanges as in Patent Document 2, it is generally difficult to significantly change the structure of the inner pipe and the outer pipe.

[0008] Therefore, for example, if the inner pipe and the outer pipe are formed separately and each is attached to another member (such as an internal combustion engine or a bulkhead) using a separate fastening means, the inner pipe and the outer pipe can be selected freely. However, when assembling such double piping to a ship, the fastening means provided at the end of the inner pipe is covered from the outside by the outer pipe, making it difficult to access the fastening means at the end of the inner pipe with tools, etc.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to facilitate the assembly of an inner pipe to other members in a piping structure in which the inner pipe and the outer pipe are formed separately. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides an inner pipe having a main passage therein, an outer pipe disposed on the outer periphery of the inner pipe and forming a sub-passage between the outer pipe and the inner pipe; A piping structure in which separate fixing portions that are fixed to other members are provided at the end of the inner pipe and the end of the outer pipe, The outer pipe has an expandable portion that is expandable in the length direction.

[0011] In this piping structure, by contracting the telescopic section of the outer pipe, the fixing section at the end of the inner pipe can be exposed without being covered by the outer pipe. By accessing the fixing section at the end of the inner pipe exposed on the outer periphery with a tool or the like from the outer periphery, the end of the inner pipe can be easily fixed to another member.

[0012] The expandable portion can have a structure including, for example, a first slide member and a second slide member, with an inner tube inserted through the inner periphery thereof, that are relatively movable in the length direction.

[0013] For example, if one end of the piping structure is fixed to the hull (e.g., a bulkhead) and the other end of the piping structure is fixed to a component (e.g., an engine) that is vibration-proof mounted to the hull, the piping structure may bend if the vibration-proof mounted component shakes relative to the hull. In this case, it is preferable that the inner pipe of the above piping structure has an inner flexible portion in at least a partial region in the length direction, and the outer pipe has an outer flexible portion arranged on the outer periphery of the inner flexible portion. This allows the inner and outer flexible portions to bend, preventing damage to the piping structure even if the vibration-proof mounted component shakes relative to the hull.

[0014] In this case, the outer tube can have, for example, one end of the stretchable portion attached to a first other member, the other end of the stretchable portion attached to one end of the flexible portion, and the other end of the flexible portion attached to a second other member. [Effects of the Invention]

[0015] As described above, according to the present invention, in a piping structure in which the inner pipe and the outer pipe are formed separately, it is possible to facilitate the assembly of the inner pipe to other members. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of a piping structure (double piping) according to one embodiment of the present invention. [Figure 2] 10 is a cross-sectional view showing the procedure for installing the above-mentioned double pipe on a ship, showing the state in which the telescopic portion of the outer pipe has been contracted to expose the downstream end of the inner pipe. FIG. [Figure 3] 10 is a cross-sectional view showing the procedure for installing the above-mentioned double pipe on a ship, showing the state in which the telescopic portion of the outer pipe has been contracted to expose the upstream end of the inner pipe. FIG. [Figure 4] 10 is a cross-sectional view showing the procedure for installing the above-mentioned double pipe on a ship, showing the state in which the telescopic portion of the outer pipe is extended and both ends of the outer pipe are abutted against other members. [Figure 5] FIG. 1 is a side view of a conventional fuel piping structure in a ship. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] FIG. 1 shows a double pipe 1 as a piping structure according to one embodiment of the present invention. This double pipe 1 constitutes a fuel supply path for a ship and is installed in an engine room 2. The double pipe 1 connects an internal combustion engine, an engine 3 (main engine or power generation engine) installed in the engine room 2, to a bulkhead 4 that separates the engine room 2 from other areas (e.g., a valve room). The engine 3 in this embodiment is an engine that uses a low-flashpoint gas or liquid fuel as fuel. For ease of explanation, in the longitudinal direction of the double pipe 1 (the left-right direction in FIG. 1), the bulkhead 4 side (left side in the figure) will be referred to as the "upstream side," and the engine 3 side (right side in the figure) will be referred to as the "downstream side."

[0019] The double pipe 1 has an inner pipe 10 and an outer pipe 20. A main passage 30 is provided inside the inner pipe 10, and a bypass passage 40 is provided between the inner pipe 10 and the outer pipe 20. The upstream end of the main passage 30 communicates with a fuel passage in a pipe 5 connected to the partition wall 4 via a through-hole 4a provided in the partition wall 4. The downstream end of the main passage 30 communicates with a fuel passage 3a provided in the engine 3. The upstream end of the bypass passage 40 communicates with a space 6 (e.g., a valve chest) partitioned from the engine room 2 via the partition wall 4 via a through-hole 4b provided in the partition wall 4. The downstream end of the bypass passage 40 communicates with a ventilation space (not shown) via a passage 3b provided in the engine 3.

[0020] When the engine 3 is operating, fuel in the fuel tank is supplied to the fuel passage 3a of the engine 3 via the fuel passage in the piping 5, the through-hole 4a in the bulkhead 4, and the main passage 30 in the inner pipe 10. Even if the inner pipe 10 is damaged and fuel leaks from the main passage 30, this fuel can be released via the sub-passage 40 into the space 6 or the ventilation space (not shown) of the engine 3, thereby preventing the fuel from leaking into the engine room 2.

[0021] The inner pipe 10 has an inner pipe body 11 and fixing portions 12 and 13 fixed to both ends of the inner pipe body 11 by welding or the like.

[0022] At least a partial region of the inner pipe body 11 in the longitudinal direction functions as the inner flexible portion. In the illustrated example, the entire inner pipe body 11 functions as the inner flexible portion. The inner pipe body 11 allows bending in the longitudinal direction, specifically, allows bending due to relative movement of both longitudinal ends in a direction perpendicular to the longitudinal direction (e.g., the up-and-down direction in FIG. 1). The inner pipe body 11 may be any type that allows bending, and may be, for example, a bellows type with alternating peaks and valleys formed in the longitudinal direction (see FIG. 1) or a braid type (not shown) made of woven wire or strips. The material of the inner pipe body 11 is not limited, and metals such as aluminum, zinc, and stainless steel, or resins such as plastic and rubber can be used. Note that the inner pipe body 11 allows slight compressive and tensile deformation in the longitudinal direction due to bending, but basically does not expand or contract in the longitudinal direction, and the allowable amount of expansion and contraction in the longitudinal direction is extremely small (e.g., less than 5% of the total length).

[0023] The fixing portion 12 on the downstream side of the inner pipe 10 is attached to a fixed portion 3c provided on the engine 3. The fixing portion 13 on the upstream side of the inner pipe 10 is attached to a fixed portion 4c provided on the partition wall 4. For example, the fixing portions 12, 13 are formed as nuts having thread grooves on their inner peripheries, and the fixed portions 3c, 4c are formed as cylindrical portions having thread grooves on their outer peripheries. The fixing portions 12, 13 are attached to the ends of the inner pipe main body 11 in a state in which they are allowed to rotate relative to the inner pipe main body 11. The thread grooves of the fixing portions 12, 13 are screwed into the thread grooves of the fixed portions 3c, 4c and tightened, thereby attaching both ends of the inner pipe 10 to the engine 3 and the partition wall 4, respectively. In this state, the downstream end of the main passage 30 provided inside the inner pipe 10 is airtightly connected to the fuel passage 3a provided in the engine 3, and the upstream end of the main passage 30 is airtightly connected to the fuel passage inside the upstream piping 5.

[0024] The inner pipe 10 is inserted into the inner periphery of the outer pipe 20. In the illustrated example, the entire length of the inner pipe 10 is disposed on the inner periphery of the outer pipe 20. The outer pipe 20 has a flexible section 21 and an expandable section 22. In the illustrated example, the flexible section 21 is provided on the upstream side, and the expandable section 22 is provided on the downstream side.

[0025] The flexible section 21 has a flexible section main body 23 and flange sections 24 and 25 fixed to both ends of the flexible section main body 23 .

[0026] At least a partial region in the longitudinal direction of the flexible section main body 23 functions as the outer flexible section. In the illustrated example, the entire flexible section main body 23 functions as the outer flexible section. The flexible section main body 23 allows bending in the longitudinal direction, specifically, allows bending due to relative movement of both ends in the longitudinal direction in a direction perpendicular to the longitudinal direction (for example, the up and down direction in Figure 1). The flexible section main body 23 is arranged on the outer periphery of the inner pipe main body 11 (inner flexible section). In the illustrated example, the entire longitudinal region of the flexible section main body 23 is arranged on the outer periphery of the inner pipe main body 11. The specific examples and materials of the flexible section main body 23 are the same as those of the inner pipe main body 11, so repeated explanations will be omitted.

[0027] The inner pipe body 11 and the flexible section body 23 may have the same configuration or different configurations. If the inner pipe body 11 and the flexible section body 23 have the same configuration, the flexible section body 23 can be given the same strength and durability as the inner pipe body 11, so even if the inner pipe body 11 is damaged and high-pressure fuel flowing through the main passage 30 leaks into the bypass passage 40, damage to the flexible section body 23 by the high-pressure fuel can be reliably prevented. On the other hand, if the flexible section body 23 does not need to have the same strength and durability as the inner pipe body 11, costs can be reduced by forming the flexible section body 23 from a material that has lower strength and durability than the inner pipe body 11.

[0028] The flanges 24, 25 of the flexible section 21 are fixed to both ends of the flexible section main body 23 by welding or the like. The downstream flange 24 is attached to the upstream end of the expandable section 22. The upstream flange 25 is attached to the partition wall 4 (second other member) with bolts 61. In other words, the upstream flange 25 of the flexible section 21 functions as a fixing part for attaching the upstream end of the outer pipe 20 to the partition wall 4.

[0029] The telescopic section 22 has an inner periphery through which the inner tube 10 is inserted and has a first slide member 26 and a second slide member 27 that are relatively movable in the longitudinal direction. The first slide member 26 has an inner tube 26a and a flange portion 26b provided at the upstream end of the inner tube 26a. The second slide member 27 is provided downstream of the first slide member 26 and has an outer tube 27a and a flange portion 27b provided at the downstream end of the outer tube 27a.

[0030] The outer peripheral surface of the inner cylinder 26a of the first slide member 26 and the inner peripheral surface of the outer cylinder 27a of the second slide member 27 are fitted together. The inner peripheral surface of the inner cylinder 26a and the outer peripheral surface of the outer cylinder 27a both have a constant shape in the longitudinal direction, and in this embodiment, both are cylindrical surfaces. This allows the inner peripheral surface of the inner cylinder 26a and the outer peripheral surface of the outer cylinder 27a to slide in the longitudinal direction, making the lengthwise dimension L of the expandable section 22 variable.

[0031] The flange portion 26b of the first slide member 26 is attached to the flange portion 24 on the downstream side of the flexible portion 21. In the illustrated example, the flange portion 26b of the first slide member 26 and the flange portion 24 of the flexible portion 21 are fixed together with bolts 63 and nuts 64. The flange portion 27b of the second slide member 27 is attached to the engine 3 (first other member). In the illustrated example, the flange portion 27b of the second slide member 27 and the engine 3 are fixed together with bolts 62. That is, the flange portion 27b of the second slide member 27 functions as a fixing portion for attaching the downstream end portion of the outer pipe 20 to the engine 3.

[0032] The double pipe 1 has an extension / retraction mechanism 50 for extending and retracting the extension section 22 in the longitudinal direction. The extension / retraction mechanism 50 has a threaded shaft 51, a fixing nut 52, and a rotating nut 53. The outer peripheral surface of the threaded shaft 51 is formed with a thread groove 51a into which the fixing nut 52 is threaded and a thread groove 51b into which the rotating nut 53 is threaded. The downstream end of the threaded shaft 51 is fixed to the flange portion 26b of the first slide member 26 by the fixing nut 52. The longitudinal region of the threaded shaft 51 where the thread groove 51b is formed is inserted into a through hole 26c provided in the flange portion 26b of the second slide member 26. In the illustrated example, rotating nuts 53 are provided on both sides of the flange portion 26b of the second slide member 26. Each rotating nut 53 is rotatably attached to the flange portion 26b of the second slide member 26 while its longitudinal movement is restricted.

[0033] When the rotating nut 53 is rotated in one direction, an axial force is generated that moves the threaded shaft 51 upstream relative to the rotating nut 53, and as a result, the threaded shaft 51 and the second slide member 27 move upstream relative to the first slide member 26. This shortens the lengthwise dimension L of the telescopic section 22, specifically, the lengthwise distance L between the upstream end face of the flange portion 26b of the first slide member 26 and the downstream end face of the flange portion 27b of the second slide member 27. On the other hand, when the rotating nut 53 is rotated in the other direction, an axial force is generated that moves the threaded shaft 51 downstream relative to the rotating nut 53, and as a result, the threaded shaft 51 and the second slide member 27 move downstream relative to the first slide member 26, and the lengthwise dimension L of the telescopic section 22 increases.

[0034] Since the engine 3 of this embodiment is an engine that uses low-flammable fuel, in order to prevent fuel from leaking into the ship from the fuel pipe connecting the fuel tank and the engine 3, the fuel pipe needs to be covered with a duct or the like. However, in areas where it is difficult to cover the fuel pipe with a duct or the like, the above-described double pipe 1 is preferably applied.

[0035] In this embodiment, the engine 3 is installed on the floor (deck) of the ship via vibration isolation means. Therefore, the engine 3 may swing significantly relative to the hull. For example, when the engine 3 shown in FIG. 1 swings up and down relative to the hull (bulkhead 4), a load is applied that causes relative vertical displacement of both ends of the double pipe 1) connecting them. In this embodiment, a partial longitudinal region of the double pipe 1 is formed only by a flexible inner pipe body 11 and a flexible flexible portion body 23 (hereinafter, this longitudinal region is referred to as the "flexible region A"). When the engine 3 swings relative to the bulkhead 4, the flexible region A of the double pipe 1 bends, thereby preventing damage to the double pipe 1.

[0036] Furthermore, when using decarbonized fuel (new fuel) such as methanol or ammonia as fuel for the engine 3, it is desirable to inject the fuel into the combustion chamber of the engine 3 at ultra-high pressure from the viewpoints of reducing unburned fuel and improving the performance of the internal combustion engine. In this case, if the engine 3 itself is equipped with a pressure boosting mechanism for high-pressure fuel injection, the fuel can be delivered from the fuel tank to the engine 3 at low pressure. However, there are currently no engines using new fuels that have a pressure boosting mechanism for high-pressure fuel injection. Furthermore, according to the International Maritime Organization (IMO) guidelines (MSC.1 / Circ.1621), the pressure boosting mechanism must be installed in the fuel adjustment room, which cannot be installed in the engine room. Therefore, the fuel must be supplied to the engine 3 in a pressurized state (e.g., 30 MPa or higher) by the pressure boosting mechanism. Therefore, if the double pipe 1 is installed downstream of the pressure boosting mechanism, the inner pipe 10 and outer pipe 20 of the double pipe 1 must have the strength and durability to withstand the above-mentioned high pressure.

[0037] Although flexible double pipes are known, it is difficult to design a double pipe that is flexible and has the strength and durability to withstand the high pressures described above for both the inner and outer pipes. Therefore, if the inner pipe 10 and the outer pipe 20 are formed separately as in the double pipe 1 described above, the inner pipe 10 and the outer pipe 20 can be designed separately, making it easier to design them to withstand the high pressures described above.

[0038] In this case, both ends of the inner pipe 10 and both ends of the outer pipe 20 need to be attached to other members (engine 3, partition wall 4) by separate fixing means (fixing parts 12, 13 and fixed parts 3c, 4c, bolts 61, 62), respectively. However, since the entire length direction of the inner pipe 10 is covered by the outer pipe 20, it is impossible to access the fixing parts 12, 13 at the ends of the inner pipe 10 from the outside, and it becomes difficult to attach the fixing parts 12, 13 of the inner pipe 10 to the fixed parts 3c, 4c of the engine 3 and the partition wall 4. In the present embodiment, by providing the expansion and contraction part 22 on the outer pipe 20 of the double pipe 1, the fixing of the fixing parts 12, 13 of the inner pipe 10 to the engine 3 and the partition wall 4 is facilitated. Hereinafter, the fixing method of the double pipe 1 to the engine 3 and the partition wall 4 will be described with reference to FIGS. 2 to 4.

[0039] First, as shown in FIG. 2, with the outer pipe 20 arranged on the outer periphery of the inner pipe 10, these are arranged between the engine 3 and the partition wall 4. In this state, or before this, the rotary nut 53 of the expansion and contraction mechanism 50 is rotated in one direction to reduce the lengthwise dimension L of the expansion and contraction part 22 to a dimension L2 (L2 < L1) smaller than the lengthwise dimension L1 (see FIG. 1) at the time of completion of attachment. Then, the entire double pipe 1 is moved closer to the upstream side to separate the flange part 27b of the second slide member 27 from the engine 3 toward the upstream side. As a result, the fixing part 12 on the downstream side of the inner pipe 10 is exposed without being covered from the outside by the second slide member 27. In this state, the fixing part 12 on the downstream side is tightened with a tool from the outside and fixed to the fixed part 3c of the engine 3.

[0040] Next, as shown in FIG. 3, with the lengthwise dimension L of the expansion and contraction part 22 still reduced, the entire double pipe 1 is moved closer to the downstream side to separate the flange part 25 on the upstream side of the flexible part 21 from the partition wall 4 toward the downstream side. As a result, the fixing part 13 on the upstream side of the inner pipe 10 is exposed without being covered from the outside by the first slide member 26. In this state, the fixing part 13 on the upstream side is tightened with a tool from the outside and fixed to the fixed part 4c of the partition wall 4.

[0041] Thereafter, the rotating nut 53 of the telescopic mechanism 50 is rotated to extend the lengthwise dimension L of the telescopic section 22 to L1, and as shown in FIG. 4, the upstream flange 25 of the flexible section 21 is brought into contact with the bulkhead 4, and the flange 27b of the second slide member 27 of the telescopic section 22 is brought into contact with the engine 3. Then, the upstream flange 25 of the flexible section 21 is fixed to the bulkhead 4 with bolts 61, the flange 27b of the second slide member 27 of the telescopic section 22 is fixed to the engine 3 with bolts 62, and the downstream flange 24 of the flexible section 21 is fixed to the flange 26b of the first slide member 26 of the telescopic section 22 with bolts 63 and nuts 64 (see FIG. 1). As a result of the above, both ends of the inner pipe 10 and both ends of the outer pipe 20 of the double piping 1 are attached to the engine 3 and the bulkhead 4, respectively, by separate fixing means.

[0042] The present invention is not limited to the above-described embodiment. Other embodiments of the present invention will be described below, but redundant description of points similar to those of the above-described embodiment will be omitted.

[0043] In the above embodiment, the double pipe 1 has the flexible region A, but if the double pipe 1 is provided in a portion where flexibility is not required, the flexible region A may be omitted. For example, the outer pipe 20 may be composed of only the expandable portion 22, and the inner pipe body 11 may be a pipe body that does not have flexibility.

[0044] Furthermore, in the above embodiment, the telescopic mechanism 50 is provided in the telescopic section 22, and is left in the double pipe 1 even after the double pipe 1 is assembled to the ship. However, this is not limiting, and for example, the telescopic mechanism may be detachable from the double pipe 1. In this case, the telescopic mechanism is used to extend and retract the telescopic section 22 when assembling the double pipe 1 to the ship. Then, after the double pipe 1 is assembled to the ship, the telescopic mechanism can be removed from the double pipe 1, so the double pipe 1 does not have a telescopic mechanism after assembly. Alternatively, if the telescopic section 22 can be extended and retracted by hand by an operator, the telescopic mechanism may be omitted.

[0045] The fixing means for attaching the inner pipe 10 and the outer pipe 20 to other members (the engine 3 and the bulkhead 4) are not limited to those described above. For example, the fixing portions (flange portions 25, 27b) of the outer pipe 20 may be formed of nuts, similar to the fixing portions 12, 13 of the inner pipe 10. In this case, the bulkhead 4 and the engine 3 are provided with fixed portions that screw onto the fixing portions (nuts) of the outer pipe 20.

[0046] The connecting means for connecting the flexible section 21 and the telescopic section 22 of the outer tube 20 is not limited to the above. For example, the downstream flange section 24 of the flexible section 21 and the flange section 26b of the first slide member 26 of the telescopic section 22 may be omitted, and the flexible section main body 23 of the flexible section 21 may be directly fixed to the inner tube 26a of the first slide member 26 by welding or the like.

[0047] In the above embodiment, the present invention is applied to a double pipe, but it can also be applied to a triple or more pipe having a pipe covering the outer periphery of an outer pipe. [Explanation of symbols]

[0048] 1. Double piping 2. Engine Room 3 Engine (first other component) 4 Partition wall (second other member) 10 Inner tube 11 Inner pipe body 12 Fixed part 13 Fixed part 20 outer tube 21 Flexible part 22 Telescopic part 23 Flexible section main body 24 flange 25 Flange part (fixed part) 26 First slide member 26a Inner cylinder 26b Flange part 27 Second slide member 27a Outer cylinder 27b Flange part (fixed part) 30 Main aisle 40 Sub-aisle 50 Telescopic mechanism 51 Screw shaft 52 Fixing nut 53 Rotating Nut A flexible area

Claims

1. an inner pipe having a main passage therein; an outer pipe disposed on the outer periphery of the inner pipe and forming a sub-passage between the outer pipe and the inner pipe; A piping structure in which separate fixing portions that are fixed to other members are provided at the end of the inner pipe and the end of the outer pipe, A piping structure in which the outer pipe has an expandable portion that is expandable in the length direction.

2. The piping structure according to claim 1, wherein the expandable portion has a first slide member and a second slide member, the first slide member and the second slide member having inner peripheries through which the inner pipe is inserted and which are movable relative to each other in the longitudinal direction.

3. the inner tube has an inner flexible portion; The piping structure according to claim 1 or 2, wherein the outer pipe has a flexible portion including an outer flexible portion disposed on the outer periphery of the inner flexible portion.

4. One end of the stretchable portion is attached to a first other member; the other end of the stretchable portion is attached to one end of the flexible portion; 4. The piping structure according to claim 3, wherein the other end of the flexible portion is attached to a second other member.

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