JP7659040B2 - Fittings and Piping Systems - Google Patents

Description

The present invention relates to a double pipe joint and a method for manufacturing a double pipe joint.

2. Description of the Related Art Double pipe joints having improved heat insulating performance between the inside and outside of the joints are known (see, for example, Patent Documents 1 and 2).
This type of double pipe joint includes an inner pipe and an outer pipe. The outer pipe is fixed to the inner pipe while covering the inner pipe from the radially outside. A hollow insulating section is formed between the inner pipe and the outer pipe. In general, the thermal conductivity of the insulating section is smaller than the thermal conductivity of the inner pipe and the outer pipe. This improves the insulating performance between the inside of the inner pipe and the outside of the double pipe joint.

JP 2001-200980 A JP 2007-292237 A

To manufacture a double pipe joint configured in this way, the inner pipe is inserted into the outer pipe. However, if the double pipe joint has a bent or branched shape, such as an elbow or tee, it becomes difficult to insert the inner pipe into the outer pipe.

The present invention was made in consideration of these problems, and aims to provide a double pipe joint that is easy to manufacture and a method for manufacturing the double pipe joint.

In order to solve the above problems, the present invention proposes the following means.
The double pipe joint of the present invention comprises an inner pipe and an outer pipe covering the radial outside of the inner pipe, a hollow insulating section is formed between the inner pipe and the outer pipe, and the outer pipe is constructed by combining a plurality of divided pieces.
In addition, the manufacturing method of the double pipe joint of the present invention is characterized in that the radial outside of the inner pipe is covered with an outer pipe formed by combining a plurality of separate divided pieces, and a hollow insulating section is formed between the inner pipe and the outer pipe.

According to these inventions, the outer pipe is formed by combining a plurality of divided pieces that are separated from each other and cover the radial outside of the inner pipe, and a hollow insulating portion is formed between the inner pipe and the outer pipe.
In this way, since there is no need to insert the inner pipe into the outer pipe, the double pipe joint can be easily manufactured.

The above double pipe joint may further include a sealing portion that seals between the end of the inner pipe and the end of the outer pipe.
According to this invention, it is possible to prevent fluids and the like from entering the thermal insulation section from between the end of the inner pipe and the end of the outer pipe.

In the above double pipe joint, the plurality of split pieces may be capable of splitting the outer pipe.
According to this invention, the external piping can be easily constructed by combining a plurality of divided pieces that are separate from one another.

The above double pipe joint may further comprise a support portion provided in the inner pipe and configured to support at least one of the plurality of split pieces.
According to this invention, at least one of the plurality of outer divided pieces is supported by the support piece, so that the heat insulating portion formed between the inner pipe and the outer pipe can be more reliably held.

The double pipe joint and the manufacturing method for the double pipe joint of the present invention make manufacturing easy.

1 is a perspective view of a piping system in which a double pipe joint according to a first embodiment of the present invention is used. FIG. 2 is a vertical cross-sectional view of the piping system. FIG. FIG. 2 is a perspective view of a joint body of the double pipe joint. 4 is a cross-sectional view taken along line A1-A1 in FIG. 3. FIG. 4 is a perspective view of a split piece of the double pipe joint. FIG. 4 is a vertical sectional view of a piping system in which a modified example of the double pipe joint of the first embodiment of the present invention is used. FIG. FIG. 11 is a perspective view of a piping system in which a double pipe joint according to a second embodiment of the present invention is used. FIG. 2 is a vertical cross-sectional view of the piping system. FIG. 4 is a longitudinal sectional view of a main portion of a double pipe joint according to a modified example of the first embodiment of the present invention. 3 is a cross-sectional view of a main portion of a double pipe joint according to a modified example of the first embodiment of the present invention, taken along the line AA in FIG. 2 . FIG. 3 is a cross-sectional view of a main portion of a double pipe joint according to a modified example of the first embodiment of the present invention, the cross-sectional view being of a portion corresponding to region B shown in FIG. 2 . FIG. 8 is a cross-sectional view of a main portion of a double pipe joint according to a modified example of the first embodiment of the present invention, taken along line CC shown in FIG. 7. FIG.

First Embodiment
A piping system in which a first embodiment of a double pipe joint according to the present invention is used will be described below with reference to Figures 1 to 8 and 11. The double pipe joint and the piping system are suitably used for, for example, air conditioning devices and plant facilities.

As shown in FIGS. 1 and 2 , the piping system 1 includes a double pipe joint 11 of the present embodiment and a pair of foam pipes (pipes) 36 .
2 and 3, the double pipe joint 11 is a so-called elbow-type joint. The double pipe joint 11 includes an inner pipe 12, sealing portions 13A and 13B, and an outer pipe 16. A hollow insulating portion 17 is formed between the inner pipe 12 and the outer pipe 16.
2 and 4, the inner pipe 12 includes a curved pipe portion 20 and straight pipe portions 21A and 21B. Fig. 4 is a perspective view of a joint body 11A, which will be described later.

The curved pipe portion 20 is formed in a tubular shape with its axis (central axis) curved on a reference plane S. In the following, a case will be described as an example in which the piping system 1 is arranged so that the reference plane S of the curved pipe portion 20 of the double pipe joint 11 is aligned along the vertical direction and the first end of the curved pipe portion 20 opens along a horizontal plane. However, the arrangement of the piping system 1 is not limited to this.
The central angle of the curved pipe portion 20 curved on the reference plane S is, for example, 91.1°. The second end portion of the curved pipe portion 20 opens downward.

The straight pipe section 21A is formed in a tubular shape extending along a horizontal plane. A first end of the straight pipe section 21A is connected to a first end of the curved pipe section 20. A first opening (opening) 22A is formed at a second end of the straight pipe section 21A. The second end of the straight pipe section 21A is the periphery of the first opening 22A in the inner pipe 12. A foaming pipe 36 is connected to the first opening 22A.
The straight pipe section 21B is formed in a tubular shape extending in the up-down direction. A first end of the straight pipe section 21B is connected to a second end of the curved pipe section 20. A second opening (opening) 22B is formed at the second end of the straight pipe section 21B. A foaming pipe 36 is connected to the second opening 22B.
In this specification, the radial direction refers to a direction perpendicular to the axis of each of the curved pipe portion 20 and the straight pipe portions 21A and 21B. That is, the radial direction is different from the axial position of the inner pipe 12.

An internal space 12a that connects the openings 22A and 22B to each other is formed in the inner pipe 12. The openings 22A and 22B have the same inner diameter.
The openings 22A and 22B are arranged such that the axes of the openings 22A and 22B are located on the reference plane S, respectively.

The sealing portion 13A is formed in a ring shape and extends from the second end of the straight pipe portion 21A toward the outside in the radial direction of the straight pipe portion 21A. The sealing portion 13A seals between the end of the inner pipe 12 and the end of the outer pipe 16.
A circular retaining portion 25A is fixed to the outer periphery of the sealing portion 13A, protruding toward the opposite side to the straight pipe portion 21A. The inner diameter of the retaining portion 25A and the outer diameter of the foaming pipe 36 are approximately equal to each other. Specifically, the inner diameter of the retaining portion 25A is slightly larger than the outer diameter of the foaming pipe 36. As a result, a small gap is formed between the inner surface of the retaining portion 25A and the foaming pipe 36 (a foamed resin layer 38 described later). This gap is used, for example, as a play when inserting the foaming pipe 36 into the retaining portion 25A, making it easier to insert the foaming pipe 36 into the retaining portion 25A. The retaining portion 25A and the foaming pipe 36 are fixed and joined by, for example, an adhesive (not shown) so that the fluid flowing through the inner pipe 12 does not flow out.
In addition, by placing a rubber ring or packing between the inner surface of the holding portion 25A and the outer surface of the foamed tube 36 (foamed resin layer 38) (the gap described above), the connection can be made expandable and detachable while preventing the fluid flowing through the inner pipe 12 from leaking out. In this case, it is preferable to provide (fix in advance) the rubber ring or packing on the inner surface of the holding portion 25A.

The sealing portion 13B is configured similarly to the sealing portion 13A. That is, the sealing portion 13B is formed in a disk shape and extends from the second end of the straight pipe portion 21B toward the radial outside of the straight pipe portion 21B. The sealing portion 13B covers the end of the heat insulating portion 17 on the second opening 22B side.
An annular holding portion 25B is fixed to the outer circumferential edge of the sealing portion 13B and projects toward the opposite side to the straight pipe portion 21B. The inner diameter of the holding portion 25B and the outer diameter of the foaming pipe 36 are approximately the same.
The sealing portions 13A and 13B may be provided on the outer pipe 16. Furthermore, the outer pipe 16, the sealing portions 13A and 13B, and the holding portions 25A and 25B may be integrally formed.

In this example, the inner pipe 12, the sealing portions 13A and 13B, and the holding portions 25A and 25B (hereinafter referred to as the fitting body 11A) are integrally formed, for example, by injection molding using a resin material.

The fitting body 11A is formed, for example, by injection molding. In this case, as shown in FIG. 2, a gate G for introducing resin into a cavity of a mold (not shown) that forms the fitting body 11A is positioned outside the curved pipe portion 20 of the inner pipe 12. The gate G and the parting line (parting surface) of the mold are positioned on the reference plane S. The fitting body 11A may have gate cut marks caused by the gate G and tiny protrusions (burrs) caused by the parting line (see protrusion 11A1 in FIG. 11).

The resin forming the joint body 11A is preferably an amorphous thermoplastic resin such as polyvinyl chloride resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), methyl methacrylate-butadiene-styrene copolymer resin (MBS resin), polycarbonate resin, etc. From the viewpoint of transparency, polyvinyl chloride resin and ABS resin are preferable, and from the viewpoint of chemical resistance, polyvinyl chloride resin is preferable.
In order to make the ABS resin transparent or translucent, it is preferable to use an ABS resin containing polymethyl methacrylate resin.
As a stabilizer to be added to a polyvinyl chloride resin in order to make the polyvinyl chloride resin transparent or translucent, a tin-based stabilizer or a Ca-Zn-based stabilizer is preferably used. As a tin-based stabilizer, it is more preferable to use one that does not contain sulfur, such as maleates or carboxylates. As a Ca-Zn-based stabilizer, a stearate is more preferable in terms of the balance between lubricity and plate-out during molding processing.

By forming the joint body 11A and the external pipe 16 from a transparent resin, the state of the drainage flowing inside the joint body 11A can be confirmed from the outside. In addition, by forming the holding parts 25A and 25B from a transparent resin, the connection state between the holding parts 25A and 25B and the foam pipe 36 can be confirmed from the outside.

The outer pipe 16 covers the outside of the inner pipe 12. The outer pipe 16 is arranged coaxially with the inner pipe 12, and is formed in a shape in which the inner pipe 12 is expanded radially outward. The inner diameter of the outer pipe 16 is larger than the outer diameter of the inner pipe 12. The outer pipe 16 is formed by combining a plurality of split pieces 28A, 28B (two in this embodiment). As shown in Figs. 5 and 6, the split pieces 28A, 28B have a shape obtained by splitting the outer pipe 16 substantially at a reference plane S. The split pieces 28A, 28B have a symmetrical (plane-symmetrical) shape with respect to the reference plane S.
The plane dividing the outer pipe 16 may be a reference plane S1 perpendicular to the reference plane S in FIG.

2 and 6, the split piece 28A includes a curved piece 30A, a straight piece 31A, and a straight piece 32A that are arranged radially outward of the curved pipe section 20, the straight pipe section 21A, and the straight pipe section 21B of the inner pipe 12. Flanges 33A and 34A are provided on the ends of the straight pieces 31A and 32A opposite to the ends connected to the curved piece 30A, respectively.
3, the divided piece 28B has curved pieces 30B, 31B, and 32B that are formed substantially symmetrically with the curved pieces 30A, 31A, and 32A of the divided piece 28A with respect to a reference plane S. Similar to the straight pieces 31A and 32A, flanges (reference numbers omitted) are provided at the ends of the straight pieces 31B and 32B.

The curved pieces 30A, 30B are generally formed in a tubular shape that is curved on the reference plane S, and cover the radial outside of the curved pipe section 20 of the inner pipe 12. The straight pieces 31A, 31B are generally formed in a tubular shape that extends along a horizontal plane, and cover the radial outside of the straight pipe section 21A of the inner pipe 12. The straight pieces 32A, 32B are generally formed in a tubular shape that extends along a horizontal plane, and cover the radial outside of the straight pipe section 21B of the inner pipe 12.

2, the split piece 28A covers the outside of the periphery of the openings 22A, 22B in the inner pipe 12 while being spaced apart from these periphery. Similarly to the split piece 28A, the split piece 28B covers the outside of the periphery of the openings 22A, 22B in the inner pipe 12 while being spaced apart from these periphery.
The divided piece 28A is in contact with each of the sealing portions 13A and 13B. Similarly to the divided piece 28A, the divided piece 28B is in contact with each of the sealing portions 13A and 13B.

The split pieces 28A, 28B are formed by injection molding using, for example, a resin material. The split pieces 28A, 28B are detachable from the joint body 11A by a known fitting structure, fastening structure, or the like. The split pieces 28A, 28B may have an adhesive margin so as to overlap in the thickness direction of the split pieces 28A, 28B (diameter direction of the inner pipe 12). The joining of the split pieces 28A, 28B does not have to be by adhesive, and a fitting structure for physically joining the split pieces 28A, 28B may be provided (details of the fitting structure will be described later). Furthermore, the joining of the split pieces 28A, 28B may be both (combined) by adhesive and physical joining, the fitting structure may also serve as an adhesive margin, and the fitting structure may have a gap for introducing adhesive.
3, the split piece 28A can be separated into a first side D1 with respect to a reference plane S with respect to the joint body 11A. The split piece 28B can be separated into a second side D2 opposite to the first side D1 with respect to the reference plane S with respect to the joint body 11A.
Air is accommodated in the heat insulating portion 17 formed between the inner pipe 12 and the outer pipe 16. The heat insulating portion 17 has a lower thermal conductivity than the inner pipe 12 and the outer pipe 16.

The aforementioned insulating portion 17 is formed on the outer surface of the inner pipe 12 over the entire length of the inner pipe 12 and over the entire circumference of the inner pipe 12. The thickness of the insulating portion 17 is approximately uniform regardless of the position between the inner pipe 12 and the outer pipe 16.

1 and 2, the foamed pipe 36 includes a non-foamed resin layer 37 and a foamed resin layer 38. The non-foamed resin layer 37 and the foamed resin layer 38 are each formed in a cylindrical shape, and the non-foamed resin layer 37 is disposed coaxially with the foamed resin layer 38 within the foamed resin layer 38.
The resin forming the non-foamed resin layer 37 is preferably a thermoplastic resin such as polyethylene, polypropylene, polyvinyl chloride resin, ABS resin, MBS resin, polycarbonate resin, etc., and from the viewpoints of chemical resistance and moldability, polyvinyl chloride resin is most preferable.

The foamed resin layer 38 is formed by foaming and molding a foamable resin composition. The foamed resin layer 38 has better heat insulation than the non-foamed resin layer 37. The foamed resin layer 38 preferably has an expansion ratio of 1.0 to 8.0 times. The foamable resin composition is preferably a rubber such as ethylene-propylene-diene rubber or chloroprene, or a thermoplastic resin such as polystyrene, polyethylene, polypropylene, polyvinyl chloride resin, ABS resin, MBS resin, or polycarbonate resin, and from the viewpoint of chemical resistance and moldability, polyvinyl chloride resin is most preferable.
The foamed pipe may have a three-layer structure including a non-foamed resin layer on the outside of the foamed resin layer 38. The foamed pipe may also have a three-layer structure including a skin layer on the outside of the foamed resin layer 38, the skin layer being the foamed resin layer 38 in a non-foamed state.

The inner diameter of the foam pipe 36 and the inner diameters of the openings 22A and 22B are equal to each other. The ends of the foam pipe 36 are butted against the sealing portions 13A and 13B of the double pipe joint 11. The foam pipe 36 is removably fixed to the double pipe joint 11 by a fixing means (not shown).

Next, a method for manufacturing the double pipe joint 11 (hereinafter, simply referred to as the manufacturing method) for manufacturing the double pipe joint 11 configured as above will be described.
First, the outside of the joint body 11A (the inner pipe 12) is covered with the outer pipe 16 which is formed by combining the multiple divided pieces 28A, 28B which are separated from each other. In this way, a hollow insulating portion 17 is formed between the inner pipe 12 and the outer pipe 16.
Through the above steps, the double pipe joint 11 is manufactured.

As described above, according to the double pipe joint 11 of the present embodiment, the divided pieces 28A, 28B separate from each other cover the radial outside of the inner pipe 12, and the divided pieces 28A, 28B are combined to form the outer pipe 16. At this time, a hollow insulating portion 17 is formed between the inner pipe 12 and the outer pipe 16.
In this way, since it is not necessary to insert the inner pipe 12 into the outer pipe 16 to construct the double pipe joint 11, the double pipe joint 11 can be easily manufactured.

The double pipe joint 11 has sealing portions 13A and 13B. This prevents fluids from entering the insulating portion 17 between the end of the inner pipe 12 and the end of the outer pipe 16. The split pieces 28A and 28B can split the outer pipe 16. Therefore, the outer pipe 16 can be easily constructed by combining the split pieces 28A and 28B that are separated from each other.

If the convex portion formed on the sealing portion 13A of the fitting body 11A interferes with the flange 33A of the external piping 16, a gap will be created between the sealing portion 13A and the flange 33A, and the air inside and outside the insulation portion 17 will be displaced, which may reduce the insulation properties of the insulation portion 17.
In contrast, according to the double pipe joint 11 of the present embodiment, the parting line when manufacturing the joint body 11A is aligned with the reference plane S for dividing the outer pipe 16 into the split pieces 28A, 28B, thereby preventing the convex portion from contacting or interfering with the flange 33A.

2, a foam packing 39 may be disposed between the sealing portions 13A, 13B and the end faces of the foam tube 36. The foam packing 39 may be a circular foam made of polyethylene, polypropylene, or the like.
When the foamed resin layer 38 of the foamed pipe 36 is an open-cell structure, even if wastewater or the like leaks from the inner piping 12 into the gap between the sealing portions 13A, 13B and the end face of the foamed pipe 36, the foamed gasket 39 can prevent the wastewater from seeping into the foamed resin layer 38 of the foamed pipe 36.

In this embodiment, the double pipe joint 11B may be connected to a pair of double pipes (pipes) 41 as in a piping system 1A shown in FIGS.
The double pipe 41 includes an inner pipe 42, an outer pipe 43, and a support member 44. In this example, the double pipe 41 includes a plurality of support members 44. The plurality of support members 44 are disposed around the axis of the inner pipe 42 at intervals, and are connected to the inner pipe 42 and the outer pipe 43, respectively. In the double pipe 41, the space between the inner pipe 42 and the outer pipe 43 is hollow.

The double pipe joint 11B has sockets 47A and 47B that protrude outward from the openings 22A and 22B on the periphery of the openings 22A and 22B, respectively. The sockets 47A and 47B are inserted into the end of the inner pipe 42 of the double pipe 41.
7. The first support portion 14 and the second support portion 15 are plate-like members extending from the outer surface of the inner pipe 12 toward the outside of the inner pipe 12.

The first support portion 14 is provided on a portion of the outer surface of the curved pipe portion 20 that is outside the curvature, an upper portion of the outer surface of the straight pipe portion 21A, and a portion of the outer surface of the straight pipe portion 21B that is spaced away from the straight pipe portion 21A. The first support portion 14 is disposed on a reference plane S. The length by which the first support portion 14 extends from the outer surfaces of the curved pipe portion 20 and the straight pipe portions 21A and 21B is approximately half the difference between the outer diameter and the inner diameter of the sealing portion 13A.
The first support portion 14 supports at least one of the divided pieces 28A and 28B relative to the inner pipe 12.
The first support portion may extend radially outward from the outer surface of the inner pipe 12. In this case, the first support portion is formed in a ring shape.

The second support portion 15 is provided on the lower part of the outer surface of the straight pipe portion 21A and on the part of the outer surface of the straight pipe portion 21B on the straight pipe portion 21A side. The second support portion 15 is disposed on the reference plane S. The length by which the second support portion 15 extends from the outer surfaces of the straight pipe portions 21A and 21B is approximately half the difference between the outer diameter and the inner diameter of the sealing portion 13A. The second support portion 15 is formed in a rectangular shape when viewed in the thickness direction of the second support portion 15.

The modified double pipe joint 11B has a support portion 14 that supports at least one of the split pieces 28A and 28B. Therefore, the insulation portion 17 formed between the inner pipe 12 and the outer pipe 16 can be more reliably held.

As in the piping system 1B shown in FIG. 11, in the double pipe joint 11C, a recess 13A1 may be formed on the surface of the sealing portion 13A facing the inner pipe 12. The recess 13A1 is recessed toward the surface opposite to the surface of the inner pipe 12. It is preferable that the recess 13A1 reaches the outer edge of the sealing portion 13A. The depth of the recess 13A1 is set to be equal to or greater than the height at which the protruding portion 11A1 formed on the joint body 11A of the double pipe joint 11C protrudes from the outer surface of the joint body 11A. The recess 13A1 may be formed around the entire circumference of the sealing portion 13A in the circumferential direction, but is preferably formed only in the vicinity of the portion where the protruding portion 11A1 is formed. The inner diameter of the straight piece 31A of the split piece 28A is set to be approximately the distance between the recess 13A1 and the central axis of the straight pipe portion 21A or greater than that distance.
In the double pipe joint 11C configured in this manner, it is possible to prevent the flange 33A of the outer pipe 16 from contacting and interfering with the convex portion 11A1 of the joint body 11A.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIGS. 9 and 10. The same components as those in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted. Only the differences will be described.
The piping system 2 shown in FIGS. 9 and 10 includes the double pipe joint 51 of this embodiment and three foam pipes 36 .
The double pipe joint 51 is a so-called Tee-type joint. The double pipe joint 51 includes an inner pipe 52, sealing portions 13A, 13B, and 13C, a first support portion 53, and an outer pipe 54. A hollow insulating portion 55 is formed between the inner pipe 52 and the outer pipe 54.

The inner pipe 52 is formed in a T-shape in a side view. In addition to the above-mentioned openings 22A and 22B, a third opening (opening) 22C is formed in the inner pipe 52. An internal space 52a is formed in the inner pipe 52, connecting the openings 22A, 22B, and 22C to each other.
The openings 22A, 22B, and 22C are arranged such that the axes of the openings 22A, 22B, and 22C are located on the reference plane S, respectively.

The sealing portion 13C and the holding portion 25C are configured similarly to the sealing portion 13A and the holding portion 25A, and are provided on the periphery of the third opening 22C in the inner pipe 52.
The first support portion 53 is provided at the upper end portion on the outer surface of the inner pipe 52 .
In this example, the inner pipe 52, the sealing portions 13A, 13B, 13C, the first support portion 53, and the holding portions 25A, 25B, 25C (hereinafter referred to as the joint body 51A) are integrally formed by, for example, injection molding using a resin material.

The outer pipe 54 is formed in a shape offset outward from the inner pipe 52 .
The outer pipe 54 is configured by combining a plurality of (two in this embodiment) divided pieces 57A, 57B. The divided pieces 57A, 57B have a shape obtained by dividing the outer pipe 54 by a reference plane S. The divided pieces 57A, 57B have a shape that is approximately symmetrical with respect to the reference plane S.
The split piece 57A can be separated into a first side D1 with respect to the joint body 51A, and the split piece 57B can be separated into a second side D2 with respect to the joint body 51A.

The double pipe joint 51 configured as described above can achieve the same effects as the double pipe joint 11 of the first embodiment.

Although the first and second embodiments of the present invention have been described above in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and the present invention also includes modifications, combinations, deletions, etc. of the configurations within the scope of the gist of the present invention. Furthermore, it goes without saying that the configurations shown in each embodiment can be used in appropriate combinations.
For example, in the first embodiment, the double pipe joint 11 does not have to include the first support portion 14. The same applies to the double pipe joint 51 of the second embodiment.

In addition, the divided pieces 57A, 57B may be provided with ribs on the outer and/or inner surfaces in order to improve the strength of the divided pieces 57A, 57B.
Furthermore, each of the split pieces 57A, 57B may be provided with a mark for aligning the split pieces 57A, 57B with each other. The mark has a shape such that the ends of the mark coincide with each other via the reference plane S when the split pieces 57A, 57B are assembled so that there is no misalignment when the split pieces 57A, 57B are assembled. The rib may also serve as the mark. The same applies to the double pipe joint 51 of the second embodiment.

The configuration in which the multiple split pieces of the outer pipe can be separated from the double pipe joint 11, 51 is not limited to the configuration described above. For example, the outer pipe may be configured by combining three or more split pieces. The number of openings formed in the inner pipe is not particularly limited as long as there are multiple openings, and the number of openings may be four or more. In other words, the double pipe joint may be configured to connect four or more pipes.

The joining of the split pieces 28A, 28B in the double pipe joint 11 shown in Fig. 2 is not limited to joining by adhesive as described above. The joining form of the split pieces 28A, 28B can be appropriately changed to another form that can restrict the split pieces 28A, 28B from moving relatively in the direction along the reference plane S and can restrict the split pieces 28A, 28B from moving relatively in the direction perpendicular to the reference plane S.
For example, the double pipe joint 11 may have a fitting structure 60 as shown in FIG. 12. The fitting structure 60 has a first fitting portion 61 provided on the divided piece 28A and a second fitting portion 62 provided on the divided piece 28B. The first fitting portion 61 has a base portion 61a protruding radially outward and a protruding portion 61b protruding circumferentially from the base portion 61a. The second fitting portion 62 has a base portion 62a protruding radially outward, a first protruding portion 62b protruding circumferentially from the base portion 62a, a second protruding portion 62c protruding radially inward from the first protruding portion 62b, and a third protruding portion 62d protruding circumferentially from the second protruding portion 62c. A recess 62e is provided between the first protruding portion 62b, the second protruding portion 62c, and the third protruding portion 62d. The protrusion 61b of the first fitting portion 61 is fitted into the recess 62e.
The fitting structure 60 may be provided over the entire axial length of the outer pipe 16 at the end where the split pieces 28A and 28B contact each other (each peripheral end of the split pieces 28A and 28B), or may be provided only on a portion of the end. Furthermore, the first fitting portion 61 may be provided on the split piece 62B, and the second fitting portion 62 may be provided on the split piece 28A. Furthermore, each of the split pieces 28A and 28B may have the first fitting portion 61 and the second fitting portion 62 alternately in the axial direction.
12, the protrusion 61b of the first fitting portion 61 and the third protrusion 62d of the second fitting portion 62 may be omitted. Even in this case, the fitting structure 60 can at least restrict the relative movement of the split pieces 28A, 28B in a direction perpendicular to the reference surface S. In this case, the function of restricting the relative movement of the split pieces 28A, 28B in a direction along the reference surface S can be realized by another joining structure. As the other joining structure, for example, there is a fitting structure that is provided at a different position along the axial direction of the outer pipe 16 with respect to the fitting structure 60 and restricts the relative movement of the split pieces 28A, 28B in a direction perpendicular to the reference surface S.
In any case, by employing the above-described fitting structure, it is possible to restrict the split pieces 28A, 28B from moving relatively in a direction along the reference surface S, and it is also possible to restrict the split pieces 28A, 28B from moving relatively in a direction perpendicular to the reference surface S. This makes it possible for the fitting structure to hold the split pieces 28A, 28B together without bonding them with an adhesive, and a certain degree of airtightness is ensured.

Furthermore, the joining of the outer pipe 16 and the sealing parts 13A and 13B in the double pipe joint 11 shown in Fig. 2 is not limited to joining by adhesive. The double pipe joint 11 may have a fitting structure 70 as shown in Fig. 13. The fitting structure 70 has a first fitting part 71 provided on the outer pipe 16 and a second fitting part 72 provided on the sealing parts 13A and 13B. The first fitting part 71 has a base part 71a protruding radially outward and a protruding part 71b protruding axially from the base part 71a. The second fitting part 72 has a base part 72a protruding radially outward, a first protruding part 72b protruding axially from the base part 72a, a second protruding part 72c protruding radially inward from the first protruding part 72b, and a third protruding part 72d protruding axially from the second protruding part 72c. A recess 72e is provided between the first protrusion 72b, the second protrusion 72c, and the third protrusion 72d. The protrusion 71b of the first fitting portion 71 is fitted into the recess 72e.
The fitting structure 70 may be provided over the entire circumferential length of the portion where the outer pipe 16 and the sealing portions 13A, 13B contact each other, or may be provided only in a portion thereof.

In addition, the joining of the split pieces 28A, 28B in the double pipe joint 11B shown in FIG. 7 is not limited to joining by adhesive as described above. The double pipe joint 11B may have a fitting structure 80 as shown in FIG. 14. The fitting structure 80 has a first fitting portion 81 provided on the split piece 28A, a second fitting portion 82 provided on the split piece 28B, and a third fitting portion 83 provided on the first support portion 14. The first fitting portion 81 has a base portion 81a protruding toward the first support portion 14 side along the circumferential direction, and a protruding portion 81b protruding radially inward from the base portion 81a. The second fitting portion 82 has a base portion 82a protruding toward the first support portion 14 side along the circumferential direction, and a protruding portion 82b protruding radially inward from the base portion 82a. A pair of third fitting portions 83 are provided with the first support portion 14 sandwiched therebetween. The third fitting portion 83 has a base portion 83a that protrudes in the circumferential direction and a protrusion portion 83b that protrudes radially outward from the base portion 83a. The first fitting portion 81 and the second fitting portion 82 are each supported from the radially inner side by the third fitting portion 83. The protrusion portion 81b of the first fitting portion 81 and the protrusion portion 83b of the third fitting portion 83 are engaged in the circumferential direction. The protrusion portion 82b of the second fitting portion 82 and the protrusion portion 83b of the third fitting portion 83 are engaged in the circumferential direction.

The location of the gate G is not limited to the outside of the curved pipe section 20 of the inner pipe 12. For example, the gate G may be provided on the outer circumferential surface of the holding section 25A or on the end surface of the holding section 25A. In any case, a gate cut mark is formed at each position where the gate G is provided.

The present invention can be used primarily to join drain pipes for discharging condensed water (drainage water) discharged from air conditioners. However, the uses of the present invention are not limited to this. For example, the present invention can be applied to pipes that require thermal insulation.

11, 11B, 11C, 51 Double pipe joint 12, 52 Inner piping 13A, 13B, 13C Sealing part 14, 53 First support part (support part)
16, 54 External piping 17, 55 Insulation section 36 Foam pipe (piping)
41 Double pipe (piping)

Claims (9)

A joint to which a pipe that is either a foam pipe having a foamed resin layer or a double pipe having a support member connecting an inner pipe and an outer pipe is connected,
The joint is
An inner pipe formed of a thermoplastic resin;
an outer pipe covering the radial outside of the inner pipe and made of a thermoplastic resin;
Equipped with
The inner pipe includes a sealing portion formed at an end of the inner pipe and sealing between the end of the pipe and the end of the outer pipe, and a holding portion formed at an end of the sealing portion and into which the pipe is inserted and connected ,
An end of the outer pipe contacts an outer surface of the sealing portion, and a hollow heat insulating portion is formed between the inner pipe, the outer pipe, and the sealing portion ;
The inner pipe, the sealing portion, and the holding portion are integrally formed as a joint by injection molding using a transparent resin . A joint to which a pipe that is either a foam pipe having a foamed resin layer or a double pipe having a support member connecting an inner pipe and an outer pipe is connected,
The joint is
An inner pipe formed of a thermoplastic resin;
an outer pipe covering the radial outside of the inner pipe and made of a thermoplastic resin;
Equipped with
The inner pipe includes a sealing portion formed at an end of the inner pipe and sealing between the end of the pipe and the end of the outer pipe, and a holding portion formed at an end of the sealing portion and into which the pipe is inserted and connected ,
A hollow heat insulating portion is formed between the inner pipe and the outer pipe,
The inner pipe , the sealing portion, and the holding portion are integrally formed as a joint by injection molding using a transparent resin. The fitting according to claim 1 or 2, wherein the outer pipe is made of a transparent resin. 4. The joint according to claim 1, wherein the inner pipe includes a curved pipe portion, and a gate cut mark is formed on an outer peripheral surface of the curved pipe portion. 4. A joint according to claim 1, wherein a gate cut mark is formed on an outer peripheral surface or an end surface of the retaining portion. 6. The joint according to claim 1, wherein the outer pipe is configured by combining two split pieces separated by a reference plane passing through a central axis of the inner pipe. Burrs are formed on the outer peripheral surface of the inner pipe due to the cut surfaces of a mold,
The burr is disposed on the reference surface.
A joint according to claim 6. A piping system in which a piping which is either a foamed pipe having a foamed resin layer or a double pipe having a support member connecting an inner pipe and an outer pipe is connected to the joint described in any one of claims 1 to 7 . The piping system of claim 8 , further comprising a foam packing disposed between the piping and the seal.

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