Cladding pipe and composite pipe

Abstract

To stabilize a state that a cladding pipe of a composite pipe is attached to a pipe joint.SOLUTION: A resin-made cladding pipe 20 for cladding a flexible inner pipe 10 which is inserted into a pipe joint 30 and connected thereto has an inside diameter Dx which is smaller than an outside diameter Dy of an external peripheral face 34y of a cap nut 34 of the pipe joint 30, and is elastically expandable in a diameter. In a state that the inner pipe 10 which is cladded with the cladding pipe 20 is connected to the pipe joint 30, the cladding pipe 20 is attachable so that its pipe end part is cladded on the external peripheral face 34y of the cap nut 34 of the pipe joint 30.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a covering pipe that covers a flexible inner pipe suitable for transporting a fluid, and to a compound pipe including this covering pipe and the inner pipe. [Background technology]

[0002] The flexible pipe (inner pipe) for supplying hot and cold water is protected by a covering pipe to form a composite pipe, which is inserted into a pipe joint and connected.

[0003] In the composite pipe disclosed in Patent Document 1 below, a corrugated resin covering pipe having alternating peaks and valleys in the axial direction covers an inner pipe so as to be expandable and contractible in the axial direction. When this composite pipe is connected to a pipe joint, the end of the covering pipe is retracted to expose the end of the inner pipe, and the end of the inner pipe is inserted into the pipe joint. With the inner pipe connected, the covering pipe tries to return to its original state, with its tip abutting the end face of the pipe joint.

[0004] In the composite pipe disclosed in Patent Document 2 below, a resin covering pipe having a plurality of retaining protrusions covers an inner pipe. The retaining protrusions are arranged at intervals in the pipe axial direction, protrude radially inward, and hold the inner pipe substantially concentric with the pipe axis with their tips to form an air layer. The inner diameter of the end of the covering pipe, a portion without the retaining protrusions, is larger than the outer diameter of the connection side end of the pipe joint. When the inner pipe of the composite pipe is inserted into the pipe joint and connected, the end of the covering pipe covers the outer circumferential surface of the connection side end of the pipe joint. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4190923 [Patent Document 2] JP 2020-193692 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the composite pipe of Patent Document 1, if the covering pipe is cut at an angle, a gap is generated between the tip of the covering pipe and the end face of the pipe joint, which deteriorates the appearance of the connection between the composite pipe and the pipe joint and exposes the inner pipe to the external environment. Also, when the end of the composite pipe is connected to the pipe joint with the pipe end facing upward, there is a risk that the covering pipe will move downward and separate from the lower end face of the pipe joint, causing a gap. If the inner pipe is exposed to the external environment due to the gap, there is a concern that the heat retention of water or hot water flowing through the inner pipe will deteriorate.

[0007] In the composite pipe of Patent Document 2, the end of the cladding pipe is not in close contact with the outer circumferential surface of the pipe joint that covers the end of the cladding pipe, and the air layer between the cladding pipe and the inner pipe is open to the outside. This may reduce the heat insulating properties of the air layer. In addition, when the end of the composite pipe is connected to the pipe joint with the pipe end facing upward, the cladding pipe may move downward and separate from the lower end surface of the pipe joint, causing a gap.

[0008] In both of the composite pipes of Patent Documents 1 and 2, the abutment state and installation state between the pipe end of the cladding pipe and the connecting end of the pipe joint were not stable. [Means for solving the problem]

[0009] The present invention has been made to solve at least one of the above problems, and a cladding tube according to one aspect of the present invention comprises: A resin covering tube that covers a flexible inner tube that is inserted into and connected to a pipe joint, The pipe joint has an inner diameter smaller than an outer diameter of the connection side end portion thereof and is elastically expandable in diameter; When the covered inner pipe and the pipe joint are in a connected state, the pipe end portion can be attached in an expanded diameter state to cover the outer circumferential surface of the connection side end portion of the pipe joint.

[0010] According to the above-mentioned configuration, the pipe end of the covering pipe covers and adheres to the outer circumferential surface of the pipe joint, so that the fitting state to the pipe joint can be stably maintained. Even if the covering pipe is cut at an angle, the influence of the oblique cut is reduced by covering the outer circumferential surface of the pipe joint. In addition, even if the pipe end is attached to the pipe joint with the pipe end facing upward, the pipe end can be prevented from moving downward. Therefore, no gap is generated between the end of the covering pipe and the end face of the pipe joint, preventing deterioration of the appearance. Also, since the inner pipe is not exposed to the external environment, deterioration of the heat retention of fluids such as water and hot water flowing through the inner pipe can be prevented.

[0011] Preferably, the pipe end portion is mountable to the outer circumferential surface of the connection side end portion of the pipe joint in a state in which the inside diameter is expanded by 102% to 120%.

[0012] Preferably, the foam contains low-density polyethylene as a main material and has an expansion ratio of 1.05 to 4 times.

[0013] Preferably, the inner tube has annular peaks and annular valleys arranged alternately in the tube axis direction, and a plurality of retaining protrusions arranged at intervals in the tube axis direction, protruding radially inward beyond the valleys, and having their tips holding the inner tube substantially concentric with the tube axis to form an air layer, wherein the inner diameter is the inner diameter of the valleys, the valleys can be attached to the outer circumferential surface in an expanded diameter state, and recesses are formed in the outer circumferential surface corresponding to each of the retaining protrusions. According to the above configuration, when the corrugated covering tube with improved flexibility is attached to the pipe joint, the valleys of the pipe end can be tightly attached to the outer circumferential surface of the pipe joint. This tight attachment prevents the air layer from communicating with the outside, so the heat insulating properties of the air layer are not reduced. The recesses allow the position of the holding protrusions, which would prevent the covering tube from being attached, to be confirmed from the outside, so the covering tube can be cut without the holding protrusions being positioned at the pipe end.

[0014] Preferably, the holding protrusion is provided in the valley portion, and a recess corresponding to this holding protrusion has a width greater than the width of the valley portion in the tube axial direction and is formed by cutting out a part of the peak portion. According to the above configuration, the recess corresponding to the holding protrusion is positioned so as to cut out a portion of the peak, thereby disrupting the appearance of the valleys aligned in the tube axis direction, thereby improving the visibility of the recess.

[0015] Preferably, said retaining projections are circumferentially spaced apart. According to the above configuration, the air layer is continuous in the tube axial direction due to the circumferentially distributed retaining protrusions, improving the thermal insulation. In addition, the risk of structures getting caught can be reduced, making it easier to insert the inner tube into the cladding tube. The recesses formed on the outer circumferential surface corresponding to each retaining protrusion are also distributed in the circumferential direction, and the presence of recesses and non-recessed parts in the circumferential direction can improve the visibility of the recesses.

[0016] Another aspect of the present invention is a composite pipe including a flexible inner pipe that is inserted into and connected to a pipe joint, and the covering pipe that covers the inner pipe. Effect of the Invention

[0017] According to the present invention, the end of the cladding tube is fitted over and in close contact with the outer circumferential surface of the pipe joint, so that the attachment state of the cladding tube to the pipe joint can be stably maintained. [Brief description of the drawings]

[0018] [Figure 1] 1 is a side view showing a cross section of only the upper half of a composite pipe including a cladding pipe according to an embodiment of the present invention. [Diagram 2] 2 is an enlarged side view showing a main part of FIG. 1, with only the upper half being cross-sectionally shown. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view showing a composite pipe connected to a pipe joint. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1 to Fig. 3, a composite pipe 1 includes a flexible inner pipe 10 and a flexible covering pipe 20 that covers the inner pipe 10. The composite pipe 1 is used, for example, as a pipe for supplying cold water or hot water. The inner pipe 10 is inserted into and connected to a pipe joint 30 shown in Fig. 4, and the inside of the inner pipe 10 becomes a fluid passage through which fluids such as cold water and hot water pass.

[0020] The inner pipe 10 is formed with a constant circular cross section over its entire length and is flexible. As the inner pipe 10, a cross-linked polyethylene (PE-X) pipe, a polybutene (PB) pipe, a polyethylene (PE) pipe, a heat-resistant polyethylene (PE-RT) pipe, or a resin pipe containing two or more of these resins can be used. Also, a metal-reinforced resin pipe containing at least one of the above resin pipes and a metal can be used. Furthermore, the inner pipe 10 may be a multi-layer pipe containing multiple resin layers that are stacked without being tightly attached to each other. The above are merely examples, and there are no particular limitations on the material of the inner tube 10 as long as it can ensure the required performance such as flexibility and fluid flowability.

[0021] The covering pipe 20 is made of a single-layered resin pipe, and may be a polyethylene (PE) pipe, a cross-linked polyethylene (PE-X) pipe, a polybutene (PB) pipe, a heat-resistant polyethylene (PE-RT) pipe, or a resin pipe containing two or more of these resins. The flexibility of the covering pipe 20 may be improved by foaming. In this case, it is preferable to use polyethylene (PE) as the main component and to use a low foaming ratio of 1.05 to 4 times, and more preferably, the foaming ratio is 1.2 to 2.5 times. This ensures flexibility that can withstand diameter expansion. In addition, when cutting, flattening resistance is effectively reduced, and uneven crushing of the covering pipe 20 can be prevented. More preferably, low-density polyethylene is used as the main component, which makes it easier to further increase flexibility. The above are merely examples, and there are no particular limitations on the material of the cladding tube 20 as long as it can ensure the required performance, such as flexibility to withstand diameter expansion, preferably flexibility to withstand diameter expansion of 105% of the diameter ratio, and protection for the inner tube 10.

[0022] As shown in Figures 1 and 2, the cladding tube 20 has annular peaks 21 and valleys 22 arranged alternately in the tube axis direction, forming a corrugated pipe shape. As shown in Figure 2, the peaks 21 are short cylindrical shapes with a constant diameter, and the cross-sectional shape of the valleys 22 along the tube axis direction is U-shaped or V-shaped. The cladding tube 20 is expandable in the tube axis direction and elastically expandable in diameter. As shown in Figure 3, the inner diameter Dx of the valleys 22 is larger than the outer diameter of the inner tube 10.

[0023] 1 to 3, the cladding tube 20 further has holding protrusions 23 that are distributed in the tube axial direction and circumferential direction and are independent of each other. In this embodiment, the holding protrusions 23 are provided in the valley portions 22, but they may be provided in the peak portions 21. Three or more holding protrusions 23 (four in this embodiment) are arranged at equal intervals in the circumferential direction at positions spaced apart by a predetermined distance in the tube axial direction.

[0024] The cross-sectional area of ​​each of the retaining projections 23 gradually decreases in the radially inward direction. The retaining projections 23 protrude radially inward beyond the valley portions 22, and the tips 230 of the retaining projections 23 are in contact with the outer circumferential surface of the inner tube 10 or face each other at a small distance, thereby retaining the inner tube 10 substantially concentrically with the tube axis of the cladding tube 20.

[0025] The retaining protrusions 23 form an air layer 24 between the cladding tube 20 and the inner tube 30. The heat insulating properties of the air layer 24 can improve the heat retention of fluids such as water and hot water flowing through the inner tube 10. In this embodiment, the retaining protrusions 23 are distributed in the circumferential direction, so that the air layer 24 is continuous without interruption over the entire area in the axial direction of the composite tube 1. This improves the heat insulating properties of the air layer 24, and therefore improves the heat retention of the fluid in the inner tube 10.

[0026] In order to effectively improve the thermal insulation of the fluid in the inner pipe 10, it is desirable to form a radial gap having an average value of 4 mm or more as an air layer 24 between the inner surface of the valley portion 22 of the covering pipe 20 and the outer surface of the inner pipe 10. In addition, since the holding protrusions 23 are distributed in the circumferential direction, the risk of structures getting caught can be reduced, making it easier to insert the inner tube 10 into the cladding tube 20. Furthermore, since the holding protrusions 23 are distributed in the tube axial direction, they do not affect the flexibility in the tube axial direction.

[0027] As shown in Figs. 1 and 2, recesses 25 corresponding to the holding protrusions 23 are formed on the outer peripheral surface of the cladding tube 20 so as to be recessed radially inward. As shown in Fig. 2, the recesses 25 have a width Wc in the tube axial direction that is larger than the width Wv of the valley portions 22, and are formed by cutting away parts of the peak portions 21. Since the width Wc of the recesses 25 is larger than the width Wv of the valley portions (Wc>Wv), the appearance of the valley portions 22 aligned in the tube axial direction is disturbed. This improves the visibility of the recesses 25. The width Wc of the recesses 25 may be set to 110% or more of the width Wv of the valley portions 22.

[0028] In the shape of the recesses 25 as viewed from a direction perpendicular to the tube axis, the cut-out portions of the peaks 21 may be triangular, rectangular, or have a shape including a circular arc, etc. In this embodiment, since the holding protrusions 23 are arranged at intervals in the circumferential direction, the recesses 25 on the outer circumferential surface of the cladding tube 80 are also arranged at intervals in the circumferential direction. The special shape of the recess 25 and the presence of recesses 25 and portions that are not recesses 25 in the circumferential direction also improve the visibility of the recesses 25 from the outside.

[0029] In this embodiment, the cladding tube 20 has an outer diameter of 42 mm or less and an average wall thickness of 0.4 mm to 0.8 mm. The intervals between the holding projections 23 in the tube axial direction are 10 mm to 210 mm.

[0030] A pipe joint 30 to which the above-mentioned compound pipe 1 is connected will be described with reference to FIG. The pipe joint 30 has a joint body 31 , an outer cylinder 32 , a water-stopping rubber ring 33 , a cap nut 34 , a retaining ring 35 , a compression ring 36 , and a jumper pin 37 .

[0031] The joint body 31 is cylindrical and has a fluid flow path 31a formed therein. A first connection part 31b that is connected to a header or a pipe is provided at one end of the joint body 31. A second connection part 31c that is connected to the inner pipe 10 is provided at the other end of the joint body 31.

[0032] An outer tube 32 is provided on the outer periphery of the second connecting part 31c. The outer tube 32 is connected to the base end of the second connecting part 31c so as to form an annular receiving part 31d between the outer tube 32 and the second connecting part 31c. Two rows of water-stopping rubber rings 33 are provided as a sealing member on the outer surface of the second connecting part 31c within the receiving part 31d.

[0033] A cap nut 34 (connection side end) is attached to the tip of the outer tube 32. The cap nut 34 has a bottom portion 34b in which a through hole 34a is formed, and a cylindrical tube portion 34x extending from the outer periphery of the bottom portion 34b toward the first connection portion 31b. The inner pipe 10 of the compound pipe 1 is inserted into the through hole 34a. The cladding tube 20 is placed on the outer periphery 34y of the tube portion 34x. The outer diameter Dy of the outer periphery 34y is larger than the inner diameter Dx of the valley portion 22 of the cladding tube 20 of the compound pipe 1 described above.

[0034] A retaining ring 35 is fixed by sandwiching its outer periphery between the bottom 34b of the cap nut 34 and the tip surface of the outer tube 32. The retaining ring 35 allows the inner tube 10 to be inserted into the receiving portion 31d, and prevents the inner tube 10 from being pulled out of the receiving portion 31d by using a locking claw.

[0035] A compression ring 36 capable of expanding and contracting in diameter is provided inside the receiving portion 31d on the rear side of the retaining ring 35. The compression ring 36 is previously engaged with the jumper pin 37 and expanded, and then narrowed in the radial direction when the tip of the inner tube 10 pushes the jumper pin 37 to the rear and removes it. As a result, the compression ring 36 tightens the inner tube 10, and the inner tube 10 is brought into close contact with the water-stopping rubber ring 33.

[0036] The connection of the compound pipe 1 to the pipe joint 30 having the above-mentioned structure will be described with reference to FIG. First, the end of the covering pipe 40 of the composite pipe 1 is moved back in the pipe axial direction to expose the end of the inner pipe 10. Next, the end of the inner pipe 10 is inserted into the receiving portion 31d of the pipe joint 30 until the jumper pin 37 that locks the compression ring 36 in an expanded state is pushed out. The compression ring 36 contracts in diameter, and the inner peripheral surface of the inner pipe 10 and the water-stopping rubber ring 33 come into close contact with each other, thereby sealing between the inner pipe 10 and the pipe joint 30. The locking claws of the retaining ring 35 bite into the outer peripheral surface of the inner pipe 10, so that the inner pipe 10 is fixed in the receiving portion 31d in a retained state.

[0037] When the inner pipe 10 is fixed in the receiving portion 31d, the valley portion 22 at the tip of the covering pipe 20 abuts against the bottom portion 34b of the cap nut 34. This is because the inner diameter Dx of the valley portion 22 is smaller than the outer diameter Dy of the outer peripheral surface 34y of the tubular portion 34x of the cap nut 34.

[0038] Next, the tube end of the cladding tube 20 is moved toward the first connection portion 31b in the tube axial direction while elastically expanding in diameter, and is placed on the outer circumferential surface 34y of the cap nut 34. Since the inner diameter Dx of the valley portion 22 of the cladding tube 20 is smaller than the outer diameter Dy of the outer circumferential surface 34y, mainly the valley portions 42 are in close contact with the outer circumferential surface 34y in an elastically deformed state. In order that at least one valley portion 42 can be in close contact with the outer circumferential surface 34y, the formation interval of the valley portions 42 in the tube axial direction is preferably equal to or less than the length of the outer circumferential surface 34y in the tube axial direction.

[0039] According to the above embodiment, the end of the covering pipe 20 of the composite pipe 1 covers and adheres to the outer circumferential surface 34y of the pipe joint 30, so that the fitting state of the covering pipe 20 to the pipe joint 30 can be stably maintained. Even when the end of the covering pipe 20 is fitted to the pipe joint 30 with the end facing upward, the end of the covering pipe 20 can be prevented from moving downward from the outer circumferential surface of the pipe joint 30, which can prevent a gap from being generated between the covering pipe 20 and the pipe joint 30. In addition, the appearance defect caused by the inner pipe 10 being exposed through the gap can be prevented. In addition, since the inner pipe is not exposed to the external environment, the deterioration of the heat retention of the fluid flowing through the inner pipe 10 can be prevented. Since the air layer 24 of the composite pipe 1 is isolated from the outside, the deterioration of the heat insulation of the air layer 24 can be prevented. In the above embodiment, the cladding tube 20 has the holding protrusions 23 that hold the inner tube 10 approximately concentrically to form the air layer 24, and these holding protrusions 23 hinder the attachment of the cladding tube 20 to the pipe joint 30. Therefore, it is necessary to prevent the holding protrusions 23 from being positioned at the tube end of the cladding tube 20. In the above embodiment, the position of the holding protrusions 23 can be confirmed by the recesses 25, so that the cladding tube 20 can be cut without the holding protrusions 23 being positioned at the tube end. Furthermore, even if the cut surface of the cladding tube 20 is oblique to a plane perpendicular to the tube axis, in the piping structure of the above embodiment, the cladding tube 20 is attached by covering and tightly fitting its tube end over the outer circumferential surface 34y of the pipe fitting 30, and the tube end of the cladding tube 20 is not abutted against the end surface of the pipe fitting 30, so the effect of the cladding tube 20 being cut at an angle is small.

[0040] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the present invention. In the above embodiment, the holding protrusions 23 are provided distributed in the circumferential direction of the cladding tube 20, but one holding protrusion may be provided over the entire circumference. The annular peaks and valleys do not necessarily have to be provided. The holding protrusion need not be provided. EXAMPLES

[0041] The following examples are provided to illustrate, but are not intended to limit the scope of the present invention. In this example, the following verifications (1) to (4) were carried out to verify the radial expansion performance of the cladding tube. (1) A corrugated pipe (cladding pipe) with an outer diameter of 30.5 mm and an inner diameter of 25.5 mm, which was made mainly of low-density polyethylene with a specific gravity of 0.921 and expanded 1.2 times, could be fitted to the outer surface of a pipe with an outer diameter of 26.0 mm by expanding the pipe end (expansion ratio 102.0%). (2) A corrugated pipe (cladding pipe) made of the same material with an outer diameter of 36.5 mm and an inner diameter of 30.7 mm could be fitted to the outer surface of a pipe with an outer diameter of 32.0 mm by expanding the end of the pipe (expansion ratio 104.2%). (3) A corrugated pipe (cladding pipe) made of the same material with an outer diameter of 30.5 mm and an inner diameter of 25.5 mm could be fitted to the outer surface of a pipe with an outer diameter of 28.0 mm by expanding the end of the pipe (expansion ratio 110%). (4) A corrugated pipe (cladding pipe) made of the same material with an outer diameter of 36.5 mm and an inner diameter of 30.7 mm could be fitted to the outer surface of a pipe with an outer diameter of 33.0 mm by expanding the end of the pipe (expansion ratio 107%).

[0042] The upper limit of the expansion ratio at which a cladding tube can be installed varies depending on the wall thickness, main material, foaming ratio, etc., but when expanding the end of the cladding tube by hand without using a machine, a guideline is 120%. The corrugated pipes (cladding pipes) used in the above verifications of this embodiment had an average wall thickness of 0.5 mm ± 0.1 mm for the corrugated pipes in verifications (1) and (3), and 0.51 mm ± 0.11 mm for the corrugated pipes in verifications (2) and (4). [Industrial Applicability]

[0043] The present invention can be applied to a covering pipe that covers a flexible inner pipe suitable for transporting a fluid, and to a compound pipe that includes this covering pipe and an inner pipe. [Explanation of symbols]

[0044] 1 Composite pipe 10 Inner tube 20 Cladding tube 21 Yamabe 22 Valley 23 Retaining protrusion 24 Air Layer 25 Recess 30 Pipe Fittings 34 Cap nut (connection end of pipe joint) 34y Outer surface of the cap nut Dx: Inside diameter of the cladding tube root Dy Outer diameter of the outer surface of the cap nut Wv Width of valley Wc Recess width

Claims

1. A resin covering tube that covers a flexible inner tube that is inserted into and connected to a pipe joint, The pipe joint has an inner diameter smaller than an outer diameter of the connection side end portion thereof and is elastically expandable in diameter; A coated pipe characterized in that, when the coated inner pipe and the pipe joint are in a connected state, the coated pipe end portion can be attached in an expanded diameter state to cover the outer circumferential surface of the connection side end portion of the pipe joint.

2. 2. The covering tube according to claim 1, characterized in that the tube end portion is attachable to an outer peripheral surface of a connection side end portion of the pipe joint in a state in which the inner diameter is expanded by 102% to 120%.

3. 3. The cladding tube according to claim 1, which comprises low-density polyethylene as a main material and has an expansion ratio of 1.05 to 4 times.

4. annular peaks and valleys alternately arranged in a tube axial direction; a plurality of holding projections arranged at intervals in the tube axial direction, protruding radially inward from the valley portion, and holding the inner tube substantially concentrically with the tube axis by their tips to form an air layer; Equipped with The inner diameter is an inner diameter of the valley portion, and the valley portion can be attached to the outer circumferential surface in an expanded diameter state, 3. The cladding tube according to claim 1, wherein recesses are formed on the outer circumferential surface of the cladding tube in correspondence with the respective holding projections.

5. The holding protrusion is provided in the valley portion, 5. The cladding tube according to claim 4, wherein the recesses corresponding to the holding protrusions have a width greater than a width of the root portions in the axial direction of the tube and are formed by cutting out a part of the peak portions.

6. 6. The cladding tube of claim 5, wherein the retention projections are circumferentially spaced apart.

7. 3. A compound pipe comprising: a flexible inner pipe which is inserted into a pipe joint for connection; and the covering pipe according to claim 1 or 2 which covers the inner pipe.

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