JP7512028B2 - Pipe Fittings - Google Patents

Description

The present invention relates to pipe fittings and piping structures.

As is well known, drainage generated by an air conditioner installed indoors is generally discharged to the outside using a drain piping structure for air conditioning equipment that has a drain up structure. The drain up structure is a structure in which the drain piping is temporarily raised to a position higher than the drain outlet of the air conditioner midway.

When constructing such a drain piping structure for an air conditioning system, the drain port of the air conditioner and the flexible hose are connected by a drain pipe and a pipe joint. The drain pipe is connected to the drain port of the air conditioner, for example. The pipe joint is, for example, an elbow or a tee. The pipe joint connects the drain pipe to the upstream side (air conditioner side) of the flexible hose.
In order to prevent drainage from accumulating and forming condensation at the connections of these pipe joints, etc., these pipe joints are generally covered with a heat insulating material or the like.

Therefore, for example, an air-conditioning drain joint (pipe joint) has been disclosed in which a portion of the pipe joint is molded from a foamed resin, thereby improving the insulation properties and eliminating the need for covering with insulation material or the like (see, for example, Patent Document 1).

In addition, a technology has been disclosed that improves the thermal insulation of a pipe joint by inserting an inner pipe section into an integrally molded outer pipe section to form a hollow layer in the joint body of the pipe joint (see, for example, Patent Document 2).

Furthermore, a technology has been disclosed for improving the thermal insulation of a pipe joint by covering an inner pipe section with an outer pipe section made of multiple components to form a hollow layer in the joint body of the pipe joint (see, for example, Patent Document 3).

Japanese Patent Application Laid-Open No. 11-201382 JP 2016-23667 A JP 2018-141505 A

However, in the pipe joint described in Patent Document 1, since the foam layer is formed by injection molding, the foaming ratio cannot be made large.
Furthermore, if the molded product is removed from the mold before it has been sufficiently cooled after foaming inside the mold, the foaming process will cause deformation of the surface layer as the product continues to foam, and the product cannot be removed until the foaming pressure has decreased, resulting in poor production efficiency.

In addition, the pipe joint described in Patent Document 2 has a spacer portion integrated with the inner pipe portion, making it difficult to insert the inner pipe portion into the outer pipe portion. In addition, if the spacer is fixed to the stopper of the outer pipe portion, the inner pipe portion cannot be inserted unless it has a split structure.

Furthermore, the pipe joint described in Patent Document 3 requires that the outer pipe parts of multiple components be covered over the inner pipe part to form the insulating layer. This results in a long joint portion of the outer pipe part, and there is still room for improvement in terms of productivity and airtightness of the hollow layer.

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide pipe fittings and piping structures that improve production efficiency and have high thermal insulation properties.

In order to solve the above problems, the present invention proposes the following means.
The pipe fitting according to the present invention is a pipe fitting for connecting a thermally insulated pipe having a coating layer made of a foamable resin formed on the outer circumference of a resin pipe, and comprises: an outer pipe section into which the thermally insulated pipe is inserted and which has an opening with an inner diameter larger than the outer diameter of the thermally insulated pipe; an inner pipe section which is disposed inside the outer pipe section and spaced from the inner surface of the outer pipe section; and a spacer section which connects the inner pipe section and the outer pipe section and forms a hollow layer between the inner pipe section and the outer pipe section, together with the inner pipe section and the outer pipe section, and is characterized in that an annular inner surface water stop section is provided inside the spacer section in contact with either the inner surface, outer surface or end of the inner pipe section over the entire circumference, and an annular outer surface water stop section is provided outside the spacer section in contact with the entire circumference of the inner surface of the outer pipe section.

According to this invention, the spacer portion is formed from a separate member from the outer pipe portion and the inner pipe portion. An annular inner surface water stop portion is provided inside the spacer portion so that it comes into contact with either the inner surface, the outer surface or the end of the inner pipe portion over the entire circumference. Furthermore, an annular outer surface water stop portion is provided outside the spacer portion so that it comes into contact with the entire circumference of the inner surface of the outer pipe portion. This allows a hollow layer to be formed between the inner pipe portion, the outer pipe portion and the spacer portion. This allows the production efficiency of the pipe joint to be increased, and the pipe joint to be provided with a hollow layer with high thermal insulation properties.

In addition, in the above pipe joint, the inner pipe portion and the outer pipe portion may be integrally molded from resin.

According to this invention, the pipe fitting is integrally molded by injection molding resin into a mold. Therefore, it is easier to manufacture than a pipe fitting constructed by combining two types of pipe fittings with different diameters. Furthermore, there is no need to insert the inner pipe part into the space inside the outer pipe part. Therefore, the overall size of the pipe fitting can be made more compact than in the past, when the diameter of the outer pipe part had to be significantly larger than that of the inner pipe part for ease of assembly. Furthermore, the outer diameter of the thermal insulation pipe connected to the outer pipe part can be kept small, and the weight can be reduced.

In addition, in the above pipe joint, the inner pipe portion and the outer pipe portion may be separate members, and the inner pipe portion may be held by the spacer portion.

According to this invention, the inner pipe section and the outer pipe section are separate members, and the inner pipe section is held by a spacer section. This allows for cases where the pipe joint cannot be molded as a single unit using a die due to the structure of the end section of the inner pipe section. It also makes it unnecessary to have a support section that connects the inner pipe section and the outer pipe section together. This prevents heat from the inner pipe section from being transferred to the outer pipe section via the joint support section, improving the insulation of the pipe joint.

In addition, in the above pipe joint, the outer pipe portion may have a stopper portion with an inner diameter smaller than the outer diameter of the thermal insulation pipe, and the end of the inner pipe portion may be located inside the stopper portion or on the same plane as the stopper portion.

According to this invention, by positioning the end of the inner tube portion on the same plane as the stopper portion, the spacer portion can be easily held by both the stopper portion and the end of the inner tube portion.
Also, even when the end of the inner pipe is positioned inside the stopper, the spacer can be held by both the stopper and the end of the inner pipe. In this case, the inner pipe can be made smaller to make the pipe joint smaller. Furthermore, the shape of the spacer can be given more freedom, for example, it can be tapered. In addition, when the inner pipe and the outer pipe are separate members, the inner pipe can be made smaller to make it easier to insert it into the outer pipe.

In addition, in the above pipe joint, the spacer portion may be located between the end of the inner pipe portion and the opening.

According to this invention, the spacer portion is positioned between the end of the inner pipe portion and the opening of the outer pipe portion, so that the end of the thermal insulation pipe can be easily brought into contact with the spacer portion. This allows the end of the thermal insulation pipe to be blocked by the spacer portion. In other words, it is possible to make it difficult for liquid in the pipe joint or the thermal insulation pipe to reach the coating layer.

In addition, in the above pipe joint, an annular foam may be provided on the side of the opening of the spacer portion.

According to this invention, an annular foam is provided on the opening side of the spacer section. This allows the end of the thermal insulation pipe to be sealed with the annular foam even if the thermal insulation pipe is cut diagonally or is not fully inserted into the pipe fitting. This increases the production efficiency of pipe fittings with a highly insulating hollow layer.

In addition, in the above pipe fitting, the outer pipe portion may be transparent.

This invention makes it easier to visually check the state of internal fluid leakage from the outside, allowing for early detection. Furthermore, rapid response such as repairs can be carried out to prevent damage from spreading.

The pipe joint according to the present invention comprises a thermal insulation pipe having a coating layer made of a foamable resin formed on the outer periphery of a resin pipe, and a pipe joint for connecting the thermal insulation pipe. The pipe joint comprises an outer pipe section into which the thermal insulation pipe is inserted and which has an opening with an inner diameter larger than the outer diameter of the thermal insulation pipe, an inner pipe section disposed inside the outer pipe section at a distance from the inner surface of the outer pipe section, and a spacer section disposed inside the outer pipe section so as to be in contact with the thermal insulation pipe, and is characterized in that the spacer section, or the spacer section and the thermal insulation pipe, block the end of the gap between the inner pipe section and the outer pipe section to form a hollow layer.

According to this invention, the end of the gap between the inner pipe section and the outer pipe section is blocked by the spacer section, or the spacer section and the thermal insulation pipe, to form a hollow layer. This can increase the production efficiency of the piping structure, and provide the pipe joint of the piping structure with a highly insulating hollow layer.

The present invention can improve production efficiency and provide pipe fittings and piping structures with high thermal insulation properties.

1 is a cross-sectional view showing a pipe joint according to a first embodiment of the present invention. FIG. 2 is a perspective view showing the pipe joint of the first embodiment. FIG. 2 is a perspective view showing an inner tube portion of the first embodiment. FIG. 2 is a side view showing the pipe joint of the first embodiment. FIG. 4 is a cross-sectional view showing a pipe joint according to a first modified example of the first embodiment. FIG. 4 is a cross-sectional view showing a pipe joint according to a second modified example of the first embodiment. FIG. 11 is a cross-sectional view showing a pipe joint according to a third modified example of the first embodiment. FIG. 11 is a cross-sectional view showing a pipe joint according to a fourth modified example of the first embodiment. FIG. 13 is a cross-sectional view showing a pipe joint according to a fifth modified example of the first embodiment. FIG. 13 is a cross-sectional view showing a pipe joint according to a sixth modified example of the first embodiment. FIG. 13 is a cross-sectional view showing a pipe joint according to a seventh modified example of the first embodiment. FIG. 13 is a cross-sectional view showing a pipe joint according to an eighth modified example of the first embodiment. FIG. 13 is a cross-sectional view showing a pipe joint according to a ninth modified example of the first embodiment. FIG. 23 is a cross-sectional view showing a pipe joint according to a tenth modified example of the first embodiment. FIG. 4 is a cross-sectional view showing a pipe joint according to a second embodiment of the present invention. FIG. 13 is a cross-sectional view showing a pipe joint of a first modified example in the second embodiment. FIG. 11 is a cross-sectional view showing a pipe joint according to a third embodiment of the present invention. FIG. 13 is a cross-sectional view showing a pipe joint of a first modified example in the third embodiment. FIG. 11 is a cross-sectional view showing a pipe joint according to a fourth embodiment of the present invention. FIG. 13 is a cross-sectional view showing a pipe joint of a first modified example in the fourth embodiment. FIG. 13 is a cross-sectional view showing a pipe joint according to a second modified example of the fourth embodiment. FIG. 13 is a cross-sectional view showing a pipe joint according to a third modified example of the fourth embodiment. FIG. 13 is a perspective view showing a pipe joint according to a fifth embodiment of the present invention. FIG. 13 is a perspective view showing an inner tube portion of a fifth embodiment. FIG. 13 is a side view showing a pipe joint of a fifth embodiment. FIG. 13 is a cross-sectional view showing a pipe joint according to a fifth embodiment. FIG. 13 is a cross-sectional view showing a pipe joint according to a sixth embodiment of the present invention. FIG. 13 is a cross-sectional view illustrating a state before the inner pipe portion is housed in the outer pipe portion of the sixth embodiment from the lateral direction. FIG. 13 is a cross-sectional view illustrating a state in which the inner pipe portion is housed in the outer pipe portion of the sixth embodiment from the lateral direction. FIG. 23 is a cross-sectional view showing a pipe joint of a first modified example in the sixth embodiment. FIG. 23 is a cross-sectional view illustrating a state before the inner pipe portion is received in the outer pipe portion of a first modified example of the sixth embodiment through the branch receiving port portion. FIG. 23 is a cross-sectional view illustrating a state in which the inner pipe portion is received in the outer pipe portion of the first modified example of the sixth embodiment through the branch receiving port portion. FIG. 13 is a cross-sectional view showing a piping structure of a seventh embodiment according to the present invention. FIG. 23 is a cross-sectional view illustrating a state before a thermal insulation pipe and a spacer portion are inserted into a pipe fitting body of a seventh embodiment. FIG. 13 is a cross-sectional view showing a piping structure of an eighth embodiment according to the present invention. FIG. 23 is a cross-sectional view illustrating a state before a thermal insulation pipe is inserted into a pipe joint of an eighth embodiment. FIG. 2 is a front view showing an apparatus for measuring fusion strength.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pipe joint and a piping structure according to an embodiment of the present invention will be described below with reference to the drawings.
[First embodiment]
As shown in FIGS. 1 to 4 , the piping structure 1 includes a pipe joint 2 and a thermal insulation pipe 3 .

(Thermal insulation pipe 3)
The thermal insulation pipe 3 is a part of a piping component composed of two kinds of straight pipes with different pipe diameters. Specifically, the thermal insulation pipe 3 is a foam pipe in which an inner pipe (resin pipe) 6 with a smaller diameter is inserted into an outer pipe 5 with a larger diameter, and a coating layer 7 made of a foamable resin is formed on the outer periphery of the inner pipe 6.
An example of the thermal insulation pipe 3 will be described below, but the thermal insulation pipe 3 is not limited to the configuration shown below. For example, the outer pipe 5 may not be present, and furthermore, various physical property values may not satisfy the following values.

The thermal insulation pipe 3 includes a tubular coating layer 7 (foamed layer) containing a vinyl chloride-based resin, an inner pipe 6 (non-foamed inner layer) provided on the inner surface of the coating layer 7 and containing a vinyl chloride-based resin, and an outer pipe 5 provided on the outer surface of the coating layer 7 and containing a vinyl chloride-based resin.
The thermal insulation pipe 3 preferably has a linear expansion coefficient of 5×10 ⁻⁵ /° C. or more and less than 7×10 ⁻⁵ /° C. If the thermal insulation pipe 3 has a large linear expansion coefficient, the stress on a receiving portion 21 (described later) of the pipe fitting 2 increases due to elongation of the thermal insulation pipe 3, and there is a risk that the receiving portion 21 may crack.

The thermal insulation pipe 3 is cut to the desired length at the construction site and connected by inserting the end into the socket 21 of the pipe joint 2. The thermal insulation pipe 3 and the pipe joint 2 form an air conditioning pipe. Therefore, inside the socket 21 of the pipe joint 2, the coating layer 7, the inner pipe 6, and the outer pipe 5 are each exposed on the end surface (cut surface) of the thermal insulation pipe 3.

By increasing the closed cell ratio of the coating layer 7, the thermal insulation pipe 3 is less susceptible to the penetration of drainage water flowing down inside the thermal insulation pipe 3, making it unnecessary to uniformly apply adhesive to the end of the air conditioning drain pipe or to provide an annular elastic body (packing) inside the pipe joint 2.

The outer diameter of the thermal insulation pipe 3 is preferably, for example, 32 mm or more and 100 mm or less. The inner diameter of the thermal insulation pipe 3 is preferably, for example, 19 mm or more and 80 mm or less. The thickness of the thermal insulation pipe 3 including the coating layer 7, the inner pipe 6, and the outer pipe 5 is preferably, for example, 6 mm or more and 10 mm or less.

The longitudinal elastic modulus of the thermal insulation pipe 3 is preferably 400 MPa or more and 1500 MPa or less, more preferably 500 MPa or more and 1300 MPa or less, and further preferably 600 MPa or more and 1000 MPa or less.
By setting the modulus of longitudinal elasticity within the above-mentioned numerical range, when the thermal insulation pipe 3 is subjected to an external force, the thermal insulation pipe 3 can flexibly follow the external force while suppressing deformation such as bending or stretching, thereby preventing the thermal insulation pipe 3 from being destroyed.

The modulus of longitudinal elasticity is also called the modulus of longitudinal elasticity or Young's modulus, and is determined from the tensile stress and tensile strain obtained by a tensile test in accordance with JIS K 7161-1:2014.
The longitudinal elastic modulus can be adjusted by the degree of polymerization of the vinyl chloride resin, the expansion ratio of the foamed layer, the thicknesses of the covering layer 7, the inner tube 6, and the outer tube 5, and the like.

<Inner tube>
The inner tube 6 contains a vinyl chloride resin. The vinyl chloride resin may be a homopolymer of a vinyl chloride monomer (polyvinyl chloride) or a copolymer of a vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer.
Examples of other monomers copolymerizable with the vinyl chloride monomer include monomers such as ethylene, propylene, allyl chloride, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, vinyl acetate, maleic anhydride, acrylonitrile, etc. These may be used alone or in combination of two or more kinds.

The vinyl chloride resins may be used alone or in combination of two or more kinds.
The inner tube 6 may contain a thermoplastic resin other than vinyl chloride resin. Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, polybutene, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, ABS resin, acrylic resin, etc. These may be used alone or in combination of two or more kinds.
In the inner tube 6, the content of the vinyl chloride resin relative to the total mass of the resin is preferably 80% by mass or more and 95% by mass or less, and more preferably 85% by mass or more and 90% by mass or less.

The thickness of the inner pipe 6 is preferably 1.0 mm to 5.0 mm, more preferably 1.5 mm to 3.5 mm. By setting the thickness of the inner pipe 6 within the above numerical range, there is no risk of the drainage water flowing inside permeating into the coating layer 7, and the thermal insulation pipe 3 can have excellent thermal insulation properties.
On the other hand, when the coating layer 7 has a high closed cell ratio, the coating layer 7 itself prevents the permeation of drainage water, so the thickness of the inner pipe 6 may be 0.6 mm or more and 1.5 mm or less, and the thermal insulation pipe 3 can be made lightweight. In addition, since the thickness of the coating layer 7 can be increased, the thermal insulation pipe 3 can have excellent thermal insulation properties.

<Coating Layer>
The coating layer 7 is formed by foaming a thermoplastic resin composition for foaming layer, which contains a resin including a vinyl chloride resin and a foaming agent. The vinyl chloride resin may be a homopolymer of vinyl chloride monomer (polyvinyl chloride) or a copolymer of vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer.

Examples of other monomers that can be copolymerized with the vinyl chloride monomer include monomers such as ethylene, propylene, allyl chloride, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, vinyl acetate, maleic anhydride, and acrylonitrile. These may be used alone or in combination of two or more.

The vinyl chloride resins may be used alone or in combination of two or more kinds.
The coating layer 7 may contain a thermoplastic resin other than a vinyl chloride resin. Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, polybutene, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, ABS resin, acrylic resin, etc. These may be used alone or in combination of two or more kinds.
In the coating layer 7, the content of the vinyl chloride resin relative to the total mass of the resin is preferably 70% by mass or more and 80% by mass or less, and more preferably 70% by mass or more and 75% by mass or less.

The mass average molecular weight of the vinyl chloride resin is preferably 37,500 or more and 70,000 or less, and more preferably 37,500 or more and 44,000 or less.
The weight average molecular weight is a value measured by gel permeation chromatography using polyethylene glycol as a standard substance.
When the vinyl chloride resin is polyvinyl chloride, the average polymerization degree of the polyvinyl chloride is preferably 600 or more and 800 or less, and more preferably 600 or more and 700 or less.
The average degree of polymerization can be calculated by dividing the mass average molecular weight by the molecular weight of chloroethylene.
The vinyl chloride resin may be the same as or different from the vinyl chloride resin.

It is preferable that the coating layer 7 contains acrylic acid, methacrylic acid, acrylic acid ester, or methacrylic acid ester (collectively referred to as acrylic polymer compounds) as a thermoplastic resin other than vinyl chloride resin. By containing an acrylic polymer, the closed cell ratio can be improved and the cell diameter can be made finer.

The mass average molecular weight of the acrylic polymer compound is preferably from 3 million to 6 million, and more preferably from 4 million to 5 million.
When the coating layer 7 contains an acrylic polymer compound, the content of the acrylic polymer compound is preferably 10 parts by mass or more and 50 parts by mass or less, more preferably 12 parts by mass or more and 36 parts by mass or less, and even more preferably 18 parts by mass or more and 24 parts by mass or less, relative to 100 parts by mass of the vinyl chloride resin.
The thickness of the coating layer 7 is preferably 4.0 mm or more and 10 mm or less.

As the foaming agent, either a volatile foaming agent or a decomposition type foaming agent may be used.
Examples of the volatile blowing agent include aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, ethers, ketones, etc. Among these, examples of the aliphatic hydrocarbons include propane, butane (normal butane, isobutane), pentane (normal pentane, isopentane, etc.), etc., and examples of the alicyclic hydrocarbons include cyclopentane, cyclohexane, etc. Examples of the halogenated hydrocarbons include one or more halogenated hydrocarbons such as trichlorofluoromethane, trichlorotrifluoroethane, tetrafluoroethane, chlorodifluoroethane, difluoroethane, etc. Furthermore, examples of the ethers include dimethyl ether, diethyl ether, etc., and examples of the ketones include acetone, methyl ethyl ketone, etc.

Examples of decomposition type foaming agents include inorganic foaming agents such as sodium bicarbonate (sodium hydrogen carbonate), sodium carbonate, ammonium bicarbonate, ammonium nitrite, azide compounds, and sodium borohydride, and organic foaming agents such as azodicarbonamide, barium azodicarboxylate, and dinitrosopentamethylenetetramine.

Alternatively, a thermally expandable capsule in which the above-mentioned hydrocarbon is encapsulated in a thermoplastic resin may be used.
Other gases such as carbon dioxide, nitrogen, and air may also be used as the foaming agent.
These may be used alone or in combination of two or more kinds.
The amount of the foaming agent used is preferably from 1 to 8 parts by mass, and more preferably from 2 to 5 parts by mass, per 100 parts by mass of the vinyl chloride resin.

The coating layer 7 may contain known stabilizers such as lead compounds (lead-based stabilizers), CaZn compounds (CaZn-based stabilizers), and tin compounds (tin-based stabilizers). In particular, the inclusion of a stabilizer containing a tin compound makes it easier to increase the thermal stability of the resin. As the tin compound, mercapto-based, laurate-based, and malate-based compounds are preferred.

The presence and content of these compounds can be confirmed by inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectrometry (ICP-AES), gas chromatography mass spectrometry (GC-MS), etc. In the case of ICP-AES, the measurements can be made in accordance with EN ISO17353:2004.
The coating layer 7 may contain a lubricant. The lubricant makes it easier to maintain the lubricity with the metal surface and between resins. As the lubricant, an ester-based, polyethylene-based, or polyethylene oxide-based lubricant is preferable.

[Expansion ratio]
The expansion ratio of the covering layer 7 is 3.5 times or more and 10 times or less, preferably 4.0 times or more and 8 times or less, and more preferably 4.5 times or more and 6.0 times or less.
By setting the expansion ratio within the above range, high thermal insulation properties can be imparted, and the thermal insulation pipe 3 can be made lightweight.
The expansion ratio can be adjusted by the type or amount of resin, the type or amount of foaming agent, production conditions, and the like.

The expansion ratio can be measured by the following method.
[Method of measuring foaming ratio]
A test piece is prepared by cutting out a section of at least 10 mm in the circumferential direction and 50 mm in the axial direction from the thermal insulation pipe 3, cutting the inner pipe 6 and the outer pipe 5 with a milling cutter, and processing only the coating layer 7 into a plate of about 50 mm in length. Four test pieces are prepared, centered on the points that divide the pipe into four equal parts in the inner circumferential direction.
The apparent density of the test piece is measured to three decimal places using a water displacement specific gravity measuring device at 23° C.±2° C. in accordance with JIS K 7112:1999, and the expansion ratio is calculated by the following formula (1).
m = γc / γ ... (1)
[In formula (1), m is the expansion ratio, γ is the apparent density (g/cm ³ ) of the coating layer 7, and γc is the density (g/cm ³ ) of the coating layer 7 when not foamed.]

The closed cell ratio of the coating layer 7 is 45% or more, preferably 60% or more, and more preferably 80% or more. The upper limit of the closed cell ratio is not particularly limited, and is practically set to 95% or less, and may be 100% or less, or may be 90% or less.
By setting the closed cell rate within the above numerical range, it is possible to improve the thermal insulation while suppressing costs, prevent the penetration of water into the coating layer 7, and prevent condensation from forming on the surface of the receiving portion 21 of the pipe fitting 2. Furthermore, when the closed cell rate of the coating layer 7 is within the above numerical range, water is less likely to penetrate from the outside even if the thickness of the outer pipe 5 described below is reduced, and there is little risk of a decrease in thermal insulation.
The closed cell ratio is measured in accordance with JIS K 7138:2006. The thermal insulation pipe 3 is cut to a length of 30 mm, cut in the circumferential direction to a circumference of 20 mm, and the inner pipe 6 and the outer pipe 5 are removed with a cutter to obtain a test piece. The volume of the test piece is measured using an air comparison type specific gravity meter under a temperature condition of 23°C ± 2°C. The volume of the test piece is measured using a water displacement type specific gravity meter under a temperature condition of 23°C ± 2°C in accordance with JIS K 7112:1999. The closed cell ratio is calculated using the following formula (2).
Cc = (Va / Vaq) × 100 ... (2)
[In formula (2), Cc is the closed cell ratio (%), Va is the air comparative volume (cm ³ ), and Vaq is the water displacement volume (cm ³ )]
The closed cell ratio can be adjusted by the type or amount of resin, the type or amount of foaming agent, production conditions, and the like.

[Welding strength]
The fusion strength between the coating layer 7 and the inner tube 6 is 1.0 MPa or more, preferably 1.5 Pa or more, and more preferably 2.0 MPa or more.
By setting the fusion strength within the above range, peeling between the coating layer 7 and the inner tube 6 can be prevented.

The fusion strength can be measured by the following method.
[Method of measuring fusion strength]
A universal testing machine 250 shown in Fig. 37 was prepared. The universal testing machine 250 includes a random punching jig 251 and two compression plates (not shown). The random punching jig 251 includes a base portion 251a and a pressing portion 251b arranged above the base portion 251a. The random punching jig 251 is sandwiched between the two compression plates (not shown).
Next, the thermal insulation pipe 3 was cut into a tubular shape having a width of 20 mm in the axial direction to prepare a test specimen. The test specimen P had an inner pipe 6, a coating layer 7, and an outer pipe 5 (not shown in FIG. 37).
Under conditions of a temperature of 23°C ± 2°C and normal humidity (45 to 85%), the test piece P is set between the base part 251a and the pressing part 251b of the universal testing machine 250. The test piece P is compressed in the tube axial direction at a speed of 10 mm/min ± 2 mm/min per minute by two compression plates. The maximum load at which the fused surfaces of the inner tube 6 and the coating layer 7 peel off is obtained, and the fusion strength is calculated by the following formulas (3) and (4).
F = W / S ... (3)
S = 3.14 × d × L ... (4)
[In the formulas (3) and (4), F is the fusion strength (MPa), W is the maximum load (N), S is the fusion area (cm ² ), d is the average outer diameter (cm) of the inner tube 6, and L is the length (cm) of the test piece P.]
The fusion strength can be adjusted by the type or amount of resin, the type or amount of foaming agent, production conditions, and the like.

[Average bubble diameter]
The average bubble diameter of the coating layer 7 is 30 μm or more and 400 μm or less, preferably 50 μm or more and 400 μm or less, more preferably 50 μm or more and 250 μm or less, and even more preferably 60 μm or more and 200 μm or less.
By setting the average cell diameter within the above numerical range, it is possible to improve the heat insulating properties and prevent the penetration of water into the coating layer 7. Even if the cells are not completely closed cells (the closed cell rate is 100%) and the cell walls are partially open, allowing water to penetrate, as long as the average cell diameter is within the above numerical range and the closed cell rate is within the above numerical range, water will not penetrate deep into the coating layer 7 and the heat insulating performance will not become a problem in practical use.
The average cell diameter can be adjusted by the type or amount of resin, the type or amount of foaming agent, production conditions, and the like.

The average cell diameter can be measured by the following method.
[Measurement of average bubble diameter]
With reference to the method described in JIS K 6402, four straight lines 9 cm long (corresponding to 1800 μm in the actual cross section) are drawn at arbitrary positions on a circumferential cross-sectional image of the coating layer 7 of an air conditioning drain pipe taken at 50 times magnification with a scanning electron microscope (SEM), and the average number of bubbles crossed by each straight line is calculated. The average bubble diameter is calculated by dividing 1800 μm by the average number of crossed bubbles.

<Outer tube>
The outer tube 5 contains a vinyl chloride resin. The vinyl chloride resin may be a homopolymer of a vinyl chloride monomer (polyvinyl chloride) or a copolymer of a vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer.
Examples of other monomers copolymerizable with the vinyl chloride monomer include monomers such as ethylene, propylene, allyl chloride, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, vinyl acetate, maleic anhydride, acrylonitrile, etc. These may be used alone or in combination of two or more kinds.

The vinyl chloride resins may be used alone or in combination of two or more kinds.
The outer tube 5 may contain a thermoplastic resin other than vinyl chloride resin. Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, polybutene, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, ABS resin, acrylic resin, etc. These may be used alone or in combination of two or more kinds.
In the outer tube 5, the content of the vinyl chloride resin relative to the total mass of the resin is preferably 80% by mass or more and 95% by mass or less, and more preferably 85% by mass or more and 90% by mass or less.

The thickness of the outer pipe 5 is preferably 0.6 mm to 1.5 mm, more preferably 1.0 mm to 1.3 mm. By making the thickness of the outer pipe 5 equal to or greater than the above-mentioned lower limit, the thermal insulation pipe 3 can be made resistant to external impacts. By making the thickness of the outer pipe 5 equal to or less than the above-mentioned upper limit, the thermal insulation pipe 3 can be made lightweight. In addition, since the thickness of the coating layer 7 can be made thick, the thermal insulation pipe 3 can be made excellent in thermal insulation.
In order to make the outer tube 5 more resistant to external impacts, the thickness of the outer tube 5 is preferably 1.0 mm or more and 5.0 mm or less, and more preferably 1.5 mm or more and 3.5 mm or less.
The outer tube 5 may contain a pigment. By containing a pigment, the outer tube 5 can have a good appearance.

(Pipe fittings)
The pipe fitting 2 is a part of a piping component used to construct a piping facility. The pipe fitting 2 is, for example, a so-called "elbow" that has a generally L-shaped overall shape. The pipe fitting 2 connects a thermal insulation pipe 3 and changes the transport direction of a fluid to an orthogonal direction. In a plan view of a virtual plane including the pipe axis of the pipe fitting 2, the pipe axis is bent in an L-shape. Hereinafter, the direction in which the pipe axis is convex in the plan view may be referred to as the outside of the pipe fitting 2. The opposite direction to the outside may be referred to as the inside of the pipe fitting 2.
The pipe joint 2 comprises a pipe joint body 10 , a spacer portion 12 , and a packing 14 .

(Pipe fitting body)
The pipe joint body 10 has an outer pipe portion 15 , an inner pipe portion 16 , and a joint support portion 17 .
The outer pipe portion 15 has socket portions 21 at both ends. The socket portion 21 has an opening 22. The thermal insulation pipe 3 is inserted into the opening 22. The opening 22 has an inner diameter larger than the outer diameter of the thermal insulation pipe 3. Hereinafter, the opening 22 may be referred to as the inside of the socket portion 21. The inner surface of the socket portion 21 (the inner surface of the opening 22) and the outer surface of the thermal insulation pipe 3 may be bonded with an adhesive. Also, a rubber ring may be provided inside the socket portion 21, and the thermal insulation pipe 3 may be fitted into the rubber ring.

The inner pipe section 16 is disposed inside the outer pipe section 15 with a gap between it and the inner surface of the outer pipe section 15. The joint support section 17 is interposed between the outer pipe section 15 and the inner pipe section 16, and integrally connects the outer pipe section 15 and the inner pipe section 16. The outer pipe section 15, the inner pipe section 16, and the joint support section 17 are integrally molded, for example, by injection molding polyvinyl chloride resin (resin) into a mold.

As shown in FIG. 3, the inner tube 16 has the appearance of a pair of cylindrical members 24 assembled in an orthogonal direction. The open ends (ends) 16a, 16b at both ends of the inner tube 16 are located on planes that are orthogonal to each other. Inside the inner tube 16, an intra-tube space 26 is formed that curves in an arc shape from one open end 16a to the other open end 16b.

The open ends 16a, 16b of the inner pipe portion 16 each have a perfectly circular cross section, and have an inner diameter that is approximately equal to the outer diameter of the inner pipe 6 of the thermal insulation pipe 3 to be connected.
In the following, in order to avoid repetition of explanation, explanations common to both opening ends 16a, 16b may be given only for opening end 16a.

As shown in FIG. 2, the outer pipe portion 15 has a pair of cylindrical socket portions 21 and an outer pipe portion main body 20 that connects the socket portions 21 and has a smaller diameter than the socket portions 21. The socket ends 21a, 21b of each socket portion 21 in the outer pipe portion 15 are located on planes that are perpendicular to each other. Inside the outer pipe portion 15, an intra-pipe space 28 is formed that curves in an arc from one socket end 21a to the other socket end 21b.

The socket ends 21a, 21b of the outer pipe portion 15 each have a perfectly circular cross section and have an inner diameter that is approximately the same as the outer diameter of the outer pipe 5 of the thermal insulation pipe 3 to be connected. Furthermore, the outer pipe portion main body 20 is formed on the inner side of the socket ends 21a, 21b, and has a diameter slightly smaller than that of the socket ends 21a, 21b. The outer pipe portion 15 is provided with a stopper portion 29 having an inner diameter smaller than the outer diameter of the thermal insulation pipe 3.
In the following, in order to avoid repetition of explanation, explanations common to both receiving end portions 21a, 21b may be given only for receiving end portion 21a.

The stopper portion 29 is disposed on the same plane as the open ends 16a, 16b of the inner pipe portion 16 in the direction of the fluid flow path. In other words, the stopper portion 29 and the open ends 16a, 16b are located on the same plane perpendicular to the pipe axis of the pipe joint 2.
Furthermore, in the pipe joint 2, the sizes of the inner pipe portion 16 and the outer pipe portion 15 are set to the same sizes as those standardized by JIS for pipe joints.

The joint support portion 17 is for supporting the inner pipe portion 16 in a state in which the inner pipe portion 16 is accommodated in the intra-pipe space 28 of the outer pipe portion 15. As shown in Fig. 3, the joint support portion 17 has a first support portion 31, a second support portion 32, a third support portion 33, and a disk support portion 34.
The first support portion 31 is a flat plate-like member bent to match the bent shapes of the inner pipe portion 16 and the outer pipe portion 15. As shown in Fig. 4, the first support portion 31 connects between the outer surface 16c of the inner pipe portion 16 and the inner surface 15a of the outer pipe portion 15, thereby supporting the inner pipe portion 16 on the outer pipe portion 15. The second support portion 32 is formed in the same shape as the first support portion 31. The second support portion 32 connects between the outer surface 16d of the inner pipe portion 16 and the inner surface 15b of the outer pipe portion 15.

As shown in Fig. 1, the third support portion 33 is located on the outer side of the pipe joint 2 with respect to the inner pipe portion 16. The third support portion 33 is formed in a generally fan-shaped flat plate shape. As shown in Fig. 4, the third support portion 33 connects between the outer surface 16e of the inner pipe portion 16 and the inner surface 15c of the outer pipe portion 15.
1, 3 and 4, the disc support portion 34 closes the pipe interior space 28 of the outer pipe portion 15 in an oblique direction (at an angle of 45° with respect to the socket ends 21 a, 21 b) at the center of the curved shape. The disc support portion 34 is formed in a generally disc shape around the entire circumference of the inner pipe portion 16.
As shown in FIG. 4, the first support portion 31, the second support portion 32 and the third support portion 33 protrude from the outer surfaces 16c, 16d, 16e of the inner tube portion 16 at intervals of 90° when viewed from the front.

The pipe fitting body 10 is integrally molded by injection molding resin into a mold, so it is easier to manufacture than, for example, a pipe fitting constructed by combining an inner pipe section and an outer pipe section of different diameters. Furthermore, there is no need to insert the inner pipe section 16 into the space inside the outer pipe section 15. Therefore, the overall size of the pipe fitting 2 can be made more compact than in the past, when the pipe diameter of the outer pipe section 15 had to be significantly larger than that of the inner pipe section 16 for ease of assembly. In addition, the outer diameter of the thermal insulation pipe 3 connected to the outer pipe section 15 can be kept small, and the weight can be reduced.

As a result, when installing piping equipment in a factory, it does not take up much space, making it possible to install it in places where it was previously difficult. In addition, the weight of the entire piping equipment can be reduced, making the installation work itself easier. In addition, since there is no need to insert an inner pipe fitting into an outer pipe fitting, it is possible to manufacture small-sized multiple pipe fittings, which was previously difficult.

Examples of the resin that forms the pipe fitting body 10 include polyethylene, polypropylene, polystyrene, polybutene, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, polyvinyl chloride, ABS resin, AAS resin, AS resin, acrylic resin, etc. In particular, amorphous resins that can be bonded with adhesives (polyvinyl chloride, ABS resin, AAS resin, AS resin, acrylic resin, etc.) are preferred.

(Spacer part)
1, the spacer portion 12 connects the inner pipe portion 16 and the outer pipe portion 15, and forms a hollow layer 36 between the inner pipe portion 16 and the outer pipe portion 15 together with the inner pipe portion 16 and the outer pipe portion 15. The spacer portion 12 is disposed coaxially with the receiving portion 21 inside (i.e., the opening 22) of the receiving portion 21 of the outer pipe portion 15. The spacer portion 12 is formed, for example, in an annular flat portion made of resin. The width of the spacer portion 12 (the difference between the outer diameter and the inner diameter of the spacer portion 12, the radial size of the spacer portion 12) is formed to be approximately the same as the wall thickness of the thermal insulation pipe 3.

The spacer portion 12 has a first flat portion 12c and a second flat portion 12d. These flat portions 12c and 12d are formed by the surfaces of the spacer portion 12 that face the tube axis direction. The first flat portion 12c faces the outer tube body 20. The second flat portion 12d faces the receiving end portions 21a and 21b (the side opposite the outer tube body 20).

In the following, the first flat portion 12c side along the tube axis direction is referred to as the inside. The second flat portion 12d side is referred to as the outside. In other words, the direction in which the outer tube body 20 is positioned relative to the receiving end portions 21a, 21b along the tube axis direction is the inside, and the direction in which the receiving end portions 21a, 21b are positioned relative to the outer tube body 20 is the outside.

The spacer portion 12 has the same shape in each of the receiving portions 21. Below, the spacer portion 12 in the receiving portion 21 on the receiving end 21a side will be described as an example, and a detailed description of the spacer portion 12 in the receiving portion 21 on the receiving end 21b side will be omitted.

The spacer portion 12 has a first inner surface water-stopping portion (inner surface water-stopping portion) 12a and a first outer surface water-stopping portion (outer surface water-stopping portion) 12b.
The first inner surface water stop portion 12a is located radially inside the spacer portion 12. The first inner surface water stop portion 12a is formed in an annular shape so as to be in contact with the open end portion 16a of the inner tube portion 16 over the entire circumference. In other words, the first inner surface water stop portion 12a is formed by the inner periphery of the spacer portion 12.

The first outer surface water stop portion 12b is located on the radially outer side of the spacer portion 12. The first outer surface water stop portion 12b is formed in an annular shape so that it can come into contact with the entire circumference of the inner surface 21c of the receiving portion 21 (the inner surface of the outer tube portion). The first outer surface water stop portion 12b is further formed in an annular shape so that it can come into contact with the entire circumference of the stopper portion 29. In other words, the first outer surface water stop portion 12b is formed by the outer periphery of the spacer portion 12.

Here, the stopper portion 29 is disposed on the same plane as the opening end 16a of the inner pipe portion 16 in the direction of the fluid flow path. Therefore, even if the spacer portion 12 is formed on a flat portion as in this embodiment, when the first outer surface water stopper portion 12b is in contact with the stopper portion 29, the first inner surface water stopper portion 12a is in contact with the entire circumference of the opening end 16a of the inner pipe portion 16. In addition, the first outer surface water stopper portion 12b is in contact with not only the stopper portion 29 but also the entire circumference of the inner surface 21c of the receiving portion 21. In this state, the spacer portion 12 is adhered (held) to the opening end 16a of the inner pipe portion 16, the inner surface 21c of the receiving portion 21, and the stopper portion 29, for example, by an adhesive.

Therefore, the spacer portion 12 can be held in contact with both the stopper portion 29 and the open end 16a of the inner pipe portion 16. By arranging such spacer portions 12 in each of the socket portions 21, both ends of the space between the inner pipe portion 16 and the outer pipe portion 15 are closed. As a result, the air between the inner pipe portion 16 and the outer pipe portion 15 is sealed, and a hollow layer 36 is formed inside the pipe fitting body 10.
Furthermore, the open end 16a of the inner pipe portion 16 is located on the same plane as the stopper portion 29. Therefore, the spacer portion 12 can be easily held by both the stopper portion 29 and the open end 16a of the inner pipe portion 16.
In this manner, in a state in which the spacer portion 12 is held by both the stopper portion 29 and the open end portion 16 a of the inner pipe portion 16 , the spacer portion 12 serves as a stopper for the thermal insulation pipe 3 .

Examples of the resin that forms the spacer portion 12 include crystalline resins (polyethylene, polypropylene, etc.) and non-crystalline resins (polyvinyl chloride, ABS resin, AAS resin, AS resin, acrylic resin, etc.).
The resin forming the spacer portion 12 is preferably any of the following resins (1) to (4): (1) The same resin as the pipe fitting body 10. (2) Amorphous resin that can be bonded with an adhesive. (3) Transparent resin. (4) Resin with high chemical resistance.
From these viewpoints, the resin forming the spacer portion 12 is preferably polyvinyl chloride or ABS resin.
The resin forming the spacer portion 12 may be foamed. In this case, it is preferable that the resin be of closed cells in order to prevent water penetration and to seal the hollow layer 36.

(rubber seal)
A packing 14 is disposed on the second flat portion 12d of the spacer portion 12. The packing 14 is an elastic body formed on an annular flat portion similar to the spacer portion 12. The packing 14 is coaxially bonded to the spacer portion 12 held in the socket portion 21, for example, by an adhesive.

An example of the gasket 14 is described below, but the gasket 14 is not limited to the configuration shown below. For example, various physical property values do not have to satisfy the following. Furthermore, the gasket 14 does not have to be adhered to the spacer portion 12. Furthermore, the shape of the gasket 14 when viewed from the front may be different from the shape of the spacer portion 12 when viewed from the front, and may be an ellipse, a polygon, or the like. Furthermore, the gasket 14 may not be present.

The thickness of the packing 14 is preferably 2 mm to 15 mm, more preferably 4 mm to 12 mm, and even more preferably 6 mm to 10 mm. If the thickness of the packing 14 is equal to or greater than the lower limit, the packing 14 maintains a suitable rigidity and is not easily bent. In particular, even if the outer diameter of the packing 14 is large, for example 60 mm or more, the packing 14 is not easily bent and is easy to hold, making it easy to attach to the receiving surface 25a. In addition, a gap is less likely to occur between the end face of the thermal insulation pipe and the elastic body, making it easier to achieve a water-stopping effect. If the thickness of the packing 14 is equal to or less than the upper limit, the length of the receiving portion 21 can be shortened, and the strength of the receiving portion 21 can be maintained.

The outer diameter of the packing 14 is equal to or smaller than the inner diameter of the receiving portion 21. In other words, when the inner diameter of the receiving portion 21 is d1 and the outer diameter of the packing 14 is d2, d2≦d1 is satisfied. It is preferable that the outer diameter of the packing 14 is smaller than the inner diameter of the receiving portion 21, i.e., d2<d1 is satisfied.
When the outer diameter of the packing 14 and the inner diameter of the receiving portion 21 satisfy the above-mentioned relationship, it becomes easy to insert the packing 14 into the receiving portion 21.

The difference d1-d2 between the inner diameter d1 of the receiving portion 21 and the outer diameter d2 of the packing 14 is preferably 0 mm or more and 4 mm or less, and more preferably greater than 0 mm and 2 mm or less. If the difference d1-d2 is equal to or greater than the lower limit, the packing 14 can be easily inserted into the receiving portion 21. If the difference d1-d2 is equal to or less than the upper limit, the central axes of the receiving portion 21 and the packing 14 can be easily aligned, and the end face of the coating layer 7 of the thermal insulation pipe 3 is less likely to be exposed, resulting in a high water-stopping effect.

Here, "outer diameter of packing" refers to the diameter of the outer edge if the outer edge shape of the packing is circular, and refers to the diameter of the circumscribing circle of the outer edge if the shape is other than circular. Also, "inner diameter of receiving part" refers to the diameter of the inner edge if the inner edge shape of the cross section perpendicular to the axial direction of the cylindrical receiving part is circular, and refers to the diameter of the circumscribing circle of the inner edge if the shape is other than circular.

In order to facilitate the insertion of the thermal insulation pipe 3 and the packing 14, it is preferable that the inner surface of the receiving portion 21 is tapered so that the diameter gradually increases from the inside to the outside in the pipe axial direction (from the stopper portion 29 side to the receiving end portion 21a side). The inner surface of the receiving portion 21 does not have to be tapered.

The inner diameter of the packing 14 is preferably equal to or greater than the inner diameter of the stopper portion 29. In other words, when the inner diameter of the packing 14 is d3 and the inner diameter of the stopper portion 29 is d4, it is preferable that d3 ≥ d4. This makes it difficult for the packing 14 to impede the flow of fluid at the connection between the pipe fitting 2 and the thermal insulation pipe 3.

The difference d3-d4 between the inner diameter d3 of the packing 14 and the inner diameter d4 of the stopper portion 29 is preferably 0 mm or more and 4 mm or less, more preferably 0 mm or more and 2 mm or less, and may be substantially 0 mm. If the difference d3-d4 is within the above numerical range, the elastic body is unlikely to protrude into the water passage portion even if it is crushed by the thermal insulation pipe, and the flow of fluid at the connection portion between the pipe joint and the thermal insulation pipe is unlikely to be obstructed.

The packing 14 is made of a resin elastic body. The packing 14 may have a skin layer on its surface.
Examples of the resin used for the packing 14 include olefin resins such as polyethylene and polypropylene, and rubbers such as chloroprene rubber and ethylene propylene diene rubber (EPDM). Only one type of resin may be used, or two or more types may be used in combination.

As the resin elastomer constituting the packing 14, a resin foam having multiple bubbles formed, substantially no holes in the bubble walls, and independent bubbles that are not interconnected is preferred.

The closed cell rate of the resin foam constituting the packing 14 is preferably 30% or more, and more preferably 50% or more. The upper limit is not particularly limited, but is practically set to 99% or less. If the closed cell rate of the packing 14 is within the above numerical range, it is possible to suppress the infiltration of water into the foamed resin layer of the thermal insulation pipe 3 inserted into the receiving portion 21 of the pipe fitting 2.

The foaming ratio of the resin foam is preferably 1.1 to 50 times, more preferably 5.0 to 45 times, and even more preferably 10 to 40 times. If the foaming ratio is equal to or greater than the lower limit, the resin foam has excellent heat insulation properties, and condensation can be prevented from occurring on the outer surface of the receiving portion 21 where the packing 14 is installed. In addition, the resin foam has excellent flexibility, and gaps are unlikely to occur between the end face of the thermal insulation pipe 3 and the packing 14, making it easy to achieve a water-stopping effect. If the foaming ratio is equal to or less than the upper limit, the packing 14 maintains a suitable rigidity and is unlikely to bend. The foaming ratio can be adjusted by the type or amount of resin, the type or amount of foaming agent, manufacturing conditions, etc.

The expansion ratio of the resin foam constituting the packing 14 can be measured in the same manner as the expansion ratio of the coating layer 7 by cutting out the resin foam from the pipe fitting 2 and using the resin foam as a test piece.
The packing 14 may contain other components (optional components) in addition to the resin and the foaming agent, as long as the effects of the present invention are not impaired. Examples of the optional components include colorants, flame retardants, antioxidants, ultraviolet absorbers, and light stabilizers.

The pipe fitting 2 is composed of the pipe fitting body 10, the spacer portion 12, and the packing 14. The thermal insulation pipe 3 is connected to the pipe fitting 2 thus constructed. Specifically, the end face of the outer pipe 5 connected to the outer pipe portion 15 (the portion corresponding to the end 3a of the thermal insulation pipe 3) is in contact with the entire circumference of the outer periphery 14a of the packing 14. In addition, the end face of the inner pipe 6 (the portion corresponding to the end 3a of the thermal insulation pipe 3) is in contact with the entire circumference of the inner periphery 14b of the packing 14.

Therefore, the end face of the outer pipe 5 and the end face of the inner pipe 6 (i.e., the end 3 a of the thermal insulation pipe 3) can be brought into contact with the packing 14. This allows the thermal insulation pipe 3 to be connected (coupled) to the pipe joint 2 in a state in which the end 3 a of the thermal insulation pipe 3 is blocked by the packing 14.
Here, the spacer portion 12 has a role as a stopper for the thermal insulation pipe 3. Therefore, the spacer portion 12 abuts against both the stopper portion 29 and the open end portion 16a of the inner pipe portion 16, and can resist the insertion pressure of the thermal insulation pipe 3.

As described above, according to the pipe fitting 2 of the first embodiment, the spacer portion 12 can be held in contact with both the stopper portion 29 and the open end 16a of the inner pipe portion 16. Thus, the hollow layer 36 can be formed by closing both ends of the gap between the inner pipe portion 16 and the outer pipe portion 15 with the spacer portion 12. This can increase the production efficiency of the pipe fitting 2, and provide the pipe fitting 2 with a hollow layer 36 with high thermal insulation properties.
It is not necessary for the spacer portion 12 alone to close the hollow layer 36. For example, a through hole may be formed in the spacer portion 12. In this case, the hollow layer 36 is not closed only by the spacer portion 12, but can be closed by the spacer portion 12 together with the packing 14 and the thermal insulation pipe 3.

Furthermore, the end 3a of the thermal insulation pipe 3 can be brought into contact with the packing 14 disposed on the second flat portion 12d of the spacer portion 12. This allows the thermal insulation pipe 3 to be connected (coupled) to the pipe joint 2 with the end 3a of the thermal insulation pipe 3 blocked by the packing 14. By coupling the pipe joint 2 to the thermal insulation pipe 3, the conveying direction of a fluid (e.g., cold water, etc.) flowing through the inner pipe 6 of the thermal insulation pipe 3 can be changed to an orthogonal direction by the L-shaped pipe joint 2. Furthermore, when cold water is flowed as a fluid through the inner pipe 6 of the thermal insulation pipe 3, a temperature drop of the outer surfaces of the thermal insulation pipe 3 and the pipe joint 2 due to the cold water flowing inside the thermal insulation pipe 3 and the pipe joint 2 can be prevented, and condensation on the outer surfaces of the thermal insulation pipe 3 and the pipe joint 2 can be prevented.
Here, the inner surfaces of the spacer portion 12 and the packing 14 are formed flush with the inner surfaces of the inner pipe portion 16 and the inner pipe 6. This makes it possible to make it difficult for the flow of fluid passing from inside the inner pipe 6 through the intra-pipe space 26 of the inner pipe portion 16 to be impeded.

In the first embodiment, an example in which the pipe joint 2 is provided with the packing 14 has been described, but the pipe joint 2 may be configured not to include the packing 14 .
Even when the pipe joint 2 does not include the packing 14, the spacer portion 12 is located between the open ends 16a, 16b of the inner pipe portion 16 and the opening 22 of the socket portion 21 in a state where it is held by the open ends 16a, 16b of the inner pipe portion 16 and the stopper portion 29. Therefore, the end 3a of the thermal insulation pipe 3 can be brought into contact with the spacer portion 12. This allows the thermal insulation pipe 3 to be connected (coupled) to the pipe joint 2 in a state where the end 3a of the thermal insulation pipe 3 is blocked by the spacer portion 12.

In the first embodiment, the opening ends 16a, 16b of the inner tube portion 16 are formed with the same thickness as the other portions of the inner tube portion 16. However, the opening ends 16a, 16b of the inner tube portion 16 may be provided with a protruding portion that expands radially outward. In this case, a large contact area of the opening ends 16a, 16b can be ensured. This makes it easier to hold the spacer portion 12 with the opening ends 16a, 16b that have the protruding portion.

Next, pipe joints according to the first to tenth variants of the present invention will be described with reference to Figures 5 to 14. In the first to tenth variants, parts that are the same as or similar to the components in the first embodiment are given the same reference numerals, and their description will be omitted, with only the differences being described.

In addition, in the following modified examples and other subsequent embodiments, to avoid repetitive explanations, only the spacer portion 12 provided in the receiving portion 21 on the receiving end 21a side will be described, but the spacer portion 12 provided in the receiving portion 21 on the receiving end 21b side has the same configuration. In addition, in some modified examples and embodiments, the gasket 14 and the thermal insulation pipe 3 are not shown.

(First Modification)
As shown in FIG. 5, a pipe joint 50 has a spacer portion 51 instead of the spacer portion 12 of the first embodiment, and the other configurations are similar to those of the pipe joint 2 of the first embodiment.
The spacer portion 51 is formed on an annular flat portion similar to the spacer portion 12 of the first embodiment. The first inner water stopper portion 12a of the spacer portion 51 has a second inner water stopper portion 51a. The second inner water stopper portion 51a protrudes from the first inner water stopper portion 12a toward the inside of the inner pipe portion 16 in an annular shape (including a discontinuous annular shape) along the inner surface 16f of the inner pipe portion 16. In other words, the second inner water stopper portion 51a is fitted into the inner pipe portion 16. In this way, the second inner water stopper portion 51a contacts the inner surface 16f of the inner pipe portion 16, so that the spacer portion 51 is held by the opening end portion 16a of the inner pipe portion 16 and the stopper portion 29. An adhesive may be used to fix the spacer portion 51.
Furthermore, by the second inner water blocking portion 51a coming into contact with the inner surface 16f of the inner tube portion 16, the sealing performance of the hollow layer 36 can be further improved.

(Second Modification)
As shown in FIG. 6, a pipe joint 55 has a spacer portion 56 instead of the spacer portion 51 of the first modified example, and the other configurations are the same as those of the pipe joint 50 of the first modified example.
The spacer portion 56 has a second inner water stop portion 51a, similar to the spacer portion 51 of the first modification, and a tapered portion 56a is formed at the tip of the second inner water stop portion 51a. The tapered portion 56a protrudes in an annular shape along the inner surface 16f of the inner pipe portion 16 from the tip of the second inner water stop portion 51a toward the inside of the inner pipe portion 16.
The inner surface 56b of the tapered portion 56a is formed in a tapered shape so as to gradually approach the inner surface 16f toward the inside of the inner pipe portion 16. This makes it possible to make it difficult for the flow of fluid passing through the intra-pipe space 26 of the inner pipe portion 16 to be obstructed.

(Third Modification)
As shown in FIG. 7, a pipe joint 60 has a spacer portion 61 instead of the spacer portion 51 of the first modified example, and the other configurations are similar to those of the pipe joint 50 of the first modified example.
The spacer portion 61 has a first outer surface water stop portion 12b like the spacer portion 51 of the first modified example, and a second outer surface water stop portion 61a is formed on the first outer surface water stop portion 12b. The second outer surface water stop portion 61a protrudes in an annular shape (including a discontinuous annular shape) from the first outer surface water stop portion 12b along the inner surface 21c of the receptacle portion 21 to the receptacle end portion 21a. This allows the spacer portion 61 to be held by the opening end portion 16a of the inner tube portion 16 and the stopper portion 29. An adhesive may be used to fix the spacer portion 61.
Furthermore, by the second outer surface water-stopping portion 61a coming into contact with the inner surface 21c of the receiving portion 21, the sealing property of the hollow layer 36 can be further improved.

(Fourth Modification)
As shown in Fig. 8, the pipe fitting 65 has an expanded diameter portion 16g in the inner pipe portion 16 of the first modification, and the other configuration is the same as that of the pipe fitting 50 of the first modification. The expanded diameter portion 16g is a portion where the second inner water stopper portion 51a of the spacer portion 51 contacts the inner pipe portion 16 and is expanded radially outward. By expanding the expanded diameter portion 16g, the step of the second inner water stopper portion 51a relative to the inner surface 16f of the inner pipe portion 16 can be suppressed. In other words, the second inner water stopper portion 51a is disposed flush with the inner surface 16f of the inner pipe portion 16. This makes it difficult to obstruct the flow of the fluid passing through the pipe space 26 of the inner pipe portion 16.

(Fifth Modification)
As shown in FIG. 9, a pipe joint 70 has a spacer portion 71 instead of the spacer portion 12 of the first embodiment, and the other configurations are similar to those of the pipe joint 2 of the first embodiment.
The spacer portion 71 is formed on an annular flat portion similar to the spacer portion 12 of the first embodiment, and has a second inner surface water stop portion 71a in the vicinity of the first inner surface water stop portion 12a. The second inner surface water stop portion 71a protrudes in an annular shape (including a discontinuous annular shape) along the outer surface 16h of the inner pipe portion 16 from the vicinity of the first inner surface water stop portion 12a toward the inside of the hollow layer 36. This allows the spacer portion 71 to be held by the opening end portion 16a of the inner pipe portion 16 and the stopper portion 29. An adhesive may be used to fix the spacer portion 71.
In addition, the second inner water stopper portion 71a comes into contact with the outer surface 16h of the inner pipe portion 16, thereby further improving the sealing performance of the hollow layer 36. Furthermore, the inner surface of the spacer portion 71 is formed flush with the inner surface 16f of the inner pipe portion 16. This makes it possible to make it difficult for the flow of fluid passing through the intra-pipe space 26 of the inner pipe portion 16 to be obstructed.

(Sixth Modification)
As shown in FIG. 10, a pipe joint 75 has a spacer portion 76 instead of the spacer portion 71 of the fifth modified example, and the other configuration is the same as that of the pipe joint 70 of the fifth modified example.
The spacer portion 76 has a flat portion 76a disposed flush with the open end 16a of the inner pipe portion 16, and the other configurations are the same as those of the spacer portion 71 of the fifth modified example. By disposing the flat portion 76a flush with the open end 16a, the bonding surface of the thermally insulated pipe 3 (see FIG. 1) at the receiving portion 21 can be shortened. This allows the pipe joint 75 to be made compact.

(Seventh Modification)
As shown in FIG. 11, a pipe joint 80 has a spacer portion 81 instead of the spacer portion 12 of the first embodiment, and the other configurations are similar to those of the pipe joint 2 of the first embodiment.
The spacer portion 81 is formed in an annular flat portion similar to the spacer portion 12 of the first embodiment. The spacer portion 81 has a second inner surface water stop portion 81a and a second outer surface water stop portion 81b. The second inner surface water stop portion 81a protrudes in an annular shape along the outer surface 16h of the inner pipe portion 16 from the vicinity of the first inner surface water stop portion 12a toward the inside of the hollow layer 36. The second outer surface water stop portion 81b protrudes in an annular shape along the inner surface 15d of the outer pipe portion 15 from the vicinity of the first outer surface water stop portion 12b toward the inside of the hollow layer 36.
From the viewpoint of water stopping, it is preferable that the second inner surface water stopping portion 81a and the second outer surface water stopping portion 81b are formed in a continuous ring shape, but they may be formed in a discontinuous ring shape.

The second inner surface water stop portion 81 a and the second outer surface water stop portion 81 b of the spacer portion 81 are pressed into the hollow layer 36, and the spacer portion 71 is held by the opening end portion 16 a of the inner tube portion 16 and the stopper portion 29. This makes it possible to easily seal the hollow layer 36 with the spacer portion 81.
In addition, by bringing the second inner surface water-stopping portion 81a into contact with the inner surface 16f of the inner pipe portion 16 and the second outer surface water-stopping portion 81b into contact with the inner surface 15d of the outer pipe portion 15, the sealing property of the hollow layer 36 can be further improved.
In addition, since the hollow layer 36 is sealed by the second inner surface water stop portion 81 a and the second outer surface water stop portion 81 b of the spacer portion 81, adhesion with an adhesive may be unnecessary. A light-curing adhesive that does not need to be dried may be used to adhere the spacer portion 81.

(Eighth Modification)
As shown in FIG. 12, a pipe joint 85 is similar in configuration to the pipe joint 80 of the seventh modified example, except that the spacer portion 81 of the seventh modified example is replaced with a spacer portion 86.
The spacer portion 86 has a water stop portion 86a instead of the second inner water stop portion 81a and the second outer water stop portion 81b of the seventh modified example. The water stop portion 86a is a portion where the second inner water stop portion 81a and the second outer water stop portion 81b of the seventh modified example are integrally connected in the radial direction. The water stop portion 86a protrudes in an annular shape from the flat portion of the spacer portion 86 toward the inside of the hollow layer 36. The inner surface 86b of the water stop portion 86a is in contact with the outer surface 16h of the inner tube portion 16. The outer surface 86c of the water stop portion 86a is in contact with the inner surface 15d of the outer tube portion 15. In other words, the inner surface 86b of the water stop portion 86a constitutes the second inner water stop portion, and the outer surface 86c of the water stop portion 86a constitutes the second outer water stop portion.

The water-stopping portion 86a of the spacer portion 86 is pressed into the hollow layer 36, and the spacer portion 86 is held by the open end portion 16a of the inner tube portion 16 and the stopper portion 29. This makes it possible to easily seal the hollow layer 36 with the spacer portion 86. Note that an adhesive (e.g., photocurable) may be used to fix the spacer portion 86.
In addition, by bringing the inner surface 86b of the water-stopping portion 86a into contact with the outer surface 16h of the inner tube portion 16 and bringing the outer surface 86c of the water-stopping portion 86a into contact with the inner surface 15d of the outer tube portion 15, the sealing property of the hollow layer 36 can be further improved.
In the eighth modified example, the water stopping portion 86a is formed as a solid body, but the water stopping portion 86a may be formed as a hollow body. That is, the water stopping portion 86a is formed as a ring, but the water stopping portion 86a may be formed with a hollow portion arranged coaxially with the water stopping portion 86a. In this case, the hollow portion exerts a heat insulating effect similar to the hollow layer 36.

(Ninth Modification)
As shown in FIG. 13, a pipe joint 90 has a spacer portion 91 instead of the spacer portion 86 of the eighth modified example, and is otherwise similar in configuration to the pipe joint 85 of the eighth modified example.
The spacer portion 91 is the same as the spacer portion 86 of the eighth modified example except that the water stop portion 86a of the eighth modified example is replaced with a water stop portion 92. The water stop portion 92 is made of foamed resin. The material for forming the water stop portion 92 can be the same as the material exemplified for the packing 14, and therefore a specific example is omitted. The water stop portion 92 protrudes in an annular shape from the flat portion of the spacer portion 91 toward the inside of the hollow layer 36, similar to the water stop portion 86a of the eighth modified example. An inner surface 92a of the water stop portion 92 is in contact with an outer surface 16h of the inner tube portion 16. An outer surface 92b of the water stop portion 92 is in contact with an inner surface 15d of the outer tube portion 15.

The water-stopping portion 92 of the spacer portion 91 is pressed into the hollow layer 36, and the spacer portion 91 is held by the open end portion 16a of the inner tube portion 16 and the stopper portion 29. This makes it possible to easily seal the hollow layer 36 with the spacer portion 91. Note that an adhesive may be used to fix the spacer portion 91.
In addition, the sealing performance of the hollow layer 36 can be further improved by bringing the inner surface 92a of the water stop portion 92 into contact with the outer surface 16h of the inner pipe portion 16 and bringing the outer surface 92b of the water stop portion 92 into contact with the inner surface 15d of the outer pipe portion 15. In addition, by forming the water stop portion 92 from a foamed resin, the heat insulating performance of the hollow layer 36 can be further improved.
In the ninth modified example, the water stop portion 92 is formed as a solid body. However, similar to the eighth modified example, the water stop portion 92 may be formed as a hollow body.

(Tenth Modification)
As shown in FIG. 14, the pipe fitting 95 has an inner pipe engaging portion 16i at the open end 16a of the inner pipe portion 16 in the fifth modified example, and further replaces the spacer portion 71 with a spacer portion 96; otherwise, the configuration is the same as that of the pipe fitting 70 of the fifth modified example.
The inner pipe engaging portion 16 i protrudes radially outward from the open end portion 16 a of the inner pipe portion 16 .
The spacer portion 96 has a second inner surface water stop portion 96a instead of the second inner surface water stop portion 71a of the fifth modified example, and the other configurations are similar to those of the spacer portion 71 of the fifth modified example.
The second inner water stopper portion 96a protrudes in an annular shape (including a discontinuous annular shape) along the outer surface 16h of the inner pipe portion 16 from the vicinity of the first inner water stopper portion 12a toward the inside of the hollow layer 36. A spacer locking portion 96b is formed at the tip of the second inner water stopper portion 96a. The spacer locking portion 96b protrudes radially inward so as to be lockable with the inner pipe locking portion 16i.

The second inner water-stopping portion 96a of the spacer portion 96 is pushed into the hollow layer 36, and the spacer locking portion 96b is caused to climb over the inner pipe locking portion 16i, and the two are locked to each other. This makes it easier to hold the spacer locking portion 96b to the inner pipe portion 16, and the hollow layer 36 can be easily sealed by the spacer portion 96. In this way, the spacer portion 96 is held at the end of the hollow layer 36 by physical locking using the spacer locking portion 96b and the inner pipe locking portion 16i, making it possible to eliminate the need for bonding with an adhesive. In addition to physical locking, the spacer portion 96 may be bonded using an adhesive.
In the first to ninth modified examples, the spacer portion is held by adhesive or the like. However, the spacer portion of the first to ninth modified examples may be held at the end of the hollow layer 36 by physical engagement as in this modified example.

Next, pipe fittings according to the second to sixth embodiments of the present invention will be described with reference to Figs. 15 to 32, and piping structures according to the seventh and eighth embodiments will be described with reference to Figs. 33 to 36. In the second to eighth embodiments, parts that are the same as or similar to the components in the first embodiment will be given the same reference numerals, and their description will be omitted, with only the differences being described.

[Second embodiment]
A second embodiment of the present invention will be described with reference to FIGS.
As shown in Figure 15, in a pipe fitting 100, the open end 16a of the inner pipe portion 16 in the first embodiment is positioned further outward in the pipe axial direction (towards the receiving ends 21a, 21b) than the stopper portion 29, and further the spacer portion 12 is replaced with a spacer portion 101; the rest of the configuration is the same as that of the pipe fitting 2 of the first embodiment.
The open end 16 a of the inner tube portion 16 protrudes toward the socket end 21 a of the socket portion 21 beyond the stopper portion 29 and is disposed inside the socket portion 21 .
The spacer portion 101 includes a second inner surface water stop portion 101a formed on the first flat portion 12c, and a second outer surface water stop portion 101b.

The second inner surface water stopper 101a protrudes from the inside of the first flat portion 12c in a ring shape (including a discontinuous ring shape) along the outer surface 16h of the inner pipe portion 16. That is, the second inner surface water stopper 101a is in contact with the outer surface 16h of the inner pipe portion 16. The second outer surface water stopper 101b protrudes from the outside of the first flat portion 12c in a ring shape (including a discontinuous ring shape) along the inner surface 21c of the receiving portion 21 to the stopper portion 29. That is, the second outer surface water stopper 101b is in contact with the inner surface 21c of the receiving portion 21.

By bringing the second inner surface water-stopping portion 101a into contact with the outer surface 16h of the inner pipe portion 16 and bringing the second outer surface water-stopping portion 101b into contact with the inner surface 21c of the receiving portion 21, the sealing ability of the hollow layer 36 can be improved.
Moreover, by projecting the open end 16a of the inner tube 16 into the receiving portion 21, the spacer portion 101 can be disposed inside the receiving portion 21. This ensures a large volume for the hollow layer 36. Furthermore, the shape of the spacer portion 101 can be given a degree of freedom.

(First Modification)
A first modification of the second embodiment will be described with reference to FIG.
As shown in FIG. 16, a pipe fitting 105 has the spacer portion 101 of the second embodiment replaced with a spacer portion 106, and further has the packing 14 (see FIG. 1) replaced with an annular packing (annular foam) 107; the rest of the configuration is the same as that of the pipe fitting 100 of the second embodiment.
The spacer portion 106 is provided between the outer surface 16h of the inner pipe portion 16 and the inner surface 21c of the socket portion 21, and is formed in an annular shape. The inner surface of the spacer portion 106 is in contact with the outer surface 16h of the inner pipe portion 16. The outer surface of the spacer portion 106 is in contact with the inner surface 21c of the socket portion 21. This improves the sealing performance of the hollow layer 36. The spacer portion 106 has a recess 106a formed on the surface on the socket end portion 21a side of the socket portion 21.

The packing 107 is provided on the surface of the spacer portion 106 on the side of the receiving end 21a. The convex portion 107a of the packing 107 is tightly fitted into the concave portion 106a. This allows the packing 107 to seal the end 3a of the thermal insulation pipe 3 and maintain thermal insulation even if the end 3a (see FIG. 1) of the thermal insulation pipe 3 is cut diagonally or is not fully inserted into the receiving portion 21. In other words, the production efficiency of the pipe fitting 105 with the highly insulating hollow layer 36 can be improved.

[Third embodiment]
A third embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 17 , in a pipe fitting 110, the open end 16 a of the inner pipe portion 16 in the first embodiment is positioned more inward in the pipe axial direction than the stopper portion 29, and further the spacer portion 12 is replaced with a spacer portion 111; otherwise the configuration is similar to that of the pipe fitting 2 of the first embodiment.
The open end 16a of the inner pipe portion 16 is located on the opposite side of the receiving end 21a with respect to the stopper portion 29, and is disposed inside the stopper portion 29. The spacer portion 111 has a second inner surface water stop portion 111a formed on the first flat portion 12c, and a second outer surface water stop portion 111b. The second inner surface water stop portion 111a protrudes in an annular shape along the outer surface 16h of the inner pipe portion 16 from the vicinity of the first inner surface water stop portion 12a toward the inside of the hollow layer 36. The second outer surface water stop portion 111b protrudes in an annular shape along the inner surface 15d of the outer pipe portion 15 from the first outer surface water stop portion 12b toward the inside of the hollow layer 36.
From the viewpoint of water stopping, it is preferable that the second inner surface water stopping portion 111a and the second outer surface water stopping portion 111b are formed in a continuous ring shape, but they may be formed in a discontinuous ring shape.

The second inner surface water stop portion 111a and the second outer surface water stop portion 111b of the spacer portion 111 are pressed into the hollow layer 36 to seal the hollow layer 36 with the spacer portion 111. In this manner, by bringing the second inner surface water stop portion 111a into contact with the inner surface 16f of the inner tube portion 16 and the second outer surface water stop portion 111b into contact with the inner surface 15d of the outer tube portion 15, the sealing ability of the hollow layer 36 can be improved.
In addition, since the hollow layer 36 is sealed by the second inner surface water blocking portion 111a and the second outer surface water blocking portion 111b of the spacer portion 111, adhesion with an adhesive is not required. Alternatively, a light-curing adhesive may be used to adhere the spacer portion 111.

In addition, the open end 16a of the inner pipe section 16 is positioned on the opposite side of the receiving end 21a of the receiving section 21 from the stopper section 29. This allows the inner pipe section 16 to be made smaller, and the pipe joint 110 to be made smaller. Furthermore, by making the inner pipe section 16 smaller, the shape of the spacer section 111 can be made more flexible.

(First Modification)
A first modification of the third embodiment will be described with reference to FIG.
18, a pipe joint 115 is similar to the pipe joint 110 of the third embodiment in other configurations, except that the spacer portion 111 of the third embodiment is replaced with a spacer portion 116. The open end portion 16a of the inner pipe portion 16 is disposed inside the pipe joint 115 with respect to the stopper portion 29, as in the third embodiment.

The spacer portion 116 has a second inner surface water stop portion 116a formed on the first flat portion 12c. The second inner surface water stop portion 116a protrudes from the first inner surface water stop portion 12a toward the inside of the hollow layer 36 in an annular shape (including a discontinuous annular shape) along the outer surface 16h of the inner pipe portion 16. That is, the second inner surface water stop portion 116a is in contact with the outer surface 16h of the inner pipe portion 16. Also, the first inner surface water stop portion 12a of the spacer portion 116 is in contact with the open end portion 16a of the inner pipe portion 16. The first outer surface water stop portion 12b of the spacer portion 116 is in contact with the stopper portion 29.
In this manner, by positioning the open end 16a of the inner tube portion 16 more inward than the stopper portion 29, the spacer portion 116 can be held by both the stopper portion 29 and the open end 16a of the inner tube portion 16. In this state, the spacer portion 116 can improve the sealing property of the hollow layer 36.

The spacer portion 116 is tapered so that the inner surface of the first inner water stop portion 12a gradually narrows in diameter from the receiving end 21a to the opening end 16a of the inner pipe portion 16. This allows the inlet area of the first inner water stop portion 12a to be increased, making it difficult to impede the flow of fluid passing through the intra-pipe space 26 of the inner pipe portion 16.

[Fourth embodiment]
A fourth embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 19, a pipe joint 120 has a pipe joint body 121 instead of the pipe joint body 10 of the first embodiment, and the other configurations are similar to those of the pipe joint 2 of the first embodiment.
In the pipe fitting main body 121, the inner pipe portion 16 and the outer pipe portion 15 are formed as separate members, and the inner pipe portion 16 is held by the spacer portion 12. That is, the inner pipe portion 16 is supported in a state of being accommodated in the intra-pipe space 28 of the outer pipe portion 15 via the spacer portion 12. This makes it possible to manufacture the pipe fitting 120 even if, for example, the structure of the open ends 16a, 16b of the inner pipe portion 16 makes it impossible to integrally mold them in a mold.

In addition, the pipe joint 120 does not require the joint support part 17 (see FIG. 3) that connects the inner pipe part 16 and the outer pipe part 15 together. This prevents heat from the inner pipe part 16 from being transferred to the outer pipe part 15 via the joint support part 17, thereby improving the thermal insulation of the pipe joint 120.

(First Modification)
A first modification of the fourth embodiment will be described with reference to FIG.
As shown in FIG. 20, a pipe fitting 125 has an expanded diameter portion 16g in the inner pipe portion 16 of the fourth embodiment, and the spacer portion 12 is replaced with a spacer portion 51; otherwise, the configuration is the same as that of the pipe fitting 120 of the fourth embodiment.
The expanded diameter portion 16g of the inner pipe portion 16 is a portion where the second inner surface water stop portion 51a of the spacer portion 51 contacts the inner pipe portion 16 and is expanded radially outward. By expanding the expanded diameter portion 16g, the step of the second inner surface water stop portion 51a relative to the inner surface 16f of the inner pipe portion 16 can be suppressed. In other words, the second inner surface water stop portion 51a is disposed flush with the inner surface 16f of the inner pipe portion 16. This makes it difficult to impede the flow of fluid passing through the intra-pipe space 26 of the inner pipe portion 16.

(Second Modification)
A second modification of the fourth embodiment will be described with reference to FIG.
As shown in FIG. 21, a pipe joint 130 has a protruding portion 16j on the inner pipe portion 16 in the fourth embodiment, and the other configuration is similar to that of the pipe joint 120 in the fourth embodiment.
The protruding portion 16j of the inner pipe portion 16 is a portion that protrudes from the open end 16a of the inner pipe portion 16 so as to expand radially outward. Providing the protruding portion 16j at the open end 16a of the inner pipe portion 16 ensures a large contact area of the open end 16a. This makes it easier for the open end 16a with the protruding portion 16j to hold the spacer portion 12.

(Third Modification)
A third modification of the fourth embodiment will be described with reference to FIG.
As shown in FIG. 22, a pipe fitting 135 has an inner pipe engaging portion 16i on the inner pipe portion 16 in the fourth embodiment, and further replaces the spacer portion 12 with a spacer portion 96; otherwise, the configuration is the same as that of the pipe fitting 120 of the fourth embodiment.
The inner pipe locking portion 16i of the inner pipe portion 16 is a portion that protrudes radially outward from the open end portion 16a of the inner pipe portion 16. The spacer portion 96 has a second inner surface water stop portion 96a. The second inner surface water stop portion 96a protrudes in an annular shape (including discontinuous annular shapes) along the outer surface 16h of the inner pipe portion 16 from the vicinity of the first inner surface water stop portion 12a toward the inside of the hollow layer 36. A spacer locking portion 96b is formed at the tip portion of the second inner surface water stop portion 96a. The spacer locking portion 96b protrudes radially inward so as to be able to be locked to the inner pipe locking portion 16i.

The second inner water-stopping portion 96a of the spacer portion 96 is pushed into the hollow layer 36, and the spacer locking portion 96b overcomes the inner pipe locking portion 16i, locking the two together. This makes it easier to hold the spacer locking portion 96b to the inner pipe portion 16, and the hollow layer 36 can be easily sealed with the spacer portion 96. In this way, the spacer locking portion 96b and the inner pipe locking portion 16i hold the spacer portion 96 to the end of the hollow layer 36 by physical locking, making it unnecessary to use adhesive for bonding. Note that in addition to physical locking, the spacer portion 96 may be bonded using adhesive.

As described above, in the first to fourth embodiments, an L-shaped (elbow) pipe joint is exemplified, but the present invention is not limited to this, and may be applied to, for example, a T-shaped (tee) pipe joint. Below, a T-shaped (tee) pipe joint will be described as the fifth and sixth embodiments with reference to Figures 23 to 32.

[Fifth embodiment]
A fifth embodiment of the present invention will be described with reference to FIGS.
23 to 26, the pipe joint 140 is a so-called "Tee" that has a T-shape as a whole. The pipe joint 140 includes a pipe joint body 141, a spacer portion 142, and a packing (not shown).

The pipe fitting body 141 has an outer pipe portion 145, an inner pipe portion 146, and a fitting support portion 147. The outer pipe portion 145 is formed in a T-shape, and the receiving portion 21 is connected to the outer pipe 5 (see FIG. 1) of the thermal insulation pipe 3. The inner pipe portion 16 is formed in a T-shape, and is connected to the inner pipe 6 (see FIG. 1) of the thermal insulation pipe 3. The fitting support portion 147 supports the inner pipe portion 146 while it is housed in the intra-pipe space of the outer pipe portion 145.

The pipe fitting body 141 is integrally molded by injection molding polyvinyl chloride resin into a predetermined mold, similar to the pipe fitting body 10 of the first embodiment. Furthermore, the open ends (ends) 146a, 146b, 146c of the inner pipe portion 146 are disposed inside the respective socket portions 21. The open ends (ends) 146a, 146b, 146c of the inner pipe portion 146 are disposed further inward in the pipe axial direction than the socket ends 21a, 21b, 21c of the socket portions 21, respectively.
This pipe joint body 141 can be structured to connect the thermal insulation pipe 3 and to branch the fluid flowing through the inner pipe portion 146 in two directions.

As shown in FIG. 26, the spacer portion 142 is formed in a circular flat portion, for example, from polyvinyl chloride resin, similar to the spacer portion 12 of the first embodiment. In order to avoid repetitive explanations, only the spacer portion 12 provided in the receiving portion 21 on the receiving end 21a side will be described, but the spacer portions 12 provided in the receiving portion 21 on the receiving end 21b side and the receiving end 21c side have the same configuration.

In the spacer portion 142, the first inner water stopper portion 142a is fitted and contacts the open end portion 146a of the inner tube portion 146, and the first outer water stopper portion 142b is contacts the stopper portion 29. This allows each end of the gap between the inner tube portion 146 and the outer tube portion 145 to be blocked by the spacer portion 142 to form a hollow layer 152. A packing (not shown) is disposed in the spacer portion 142. The packing is formed in the same manner as the packing 14 of the first embodiment.

Here, in the case of a pipe fitting having a complex shape such as a T-shape, for example, when assembling two types of pipe fittings with different pipe diameters, if the inner pipe portion 146 and the outer pipe portion 145 are formed from separate members, it is necessary to form the outer pipe portion 145 significantly larger than the inner pipe portion 146. In contrast, with the pipe fitting 140, this problem can be solved by integrally molding the pipe fitting body 141 by injection molding. As a result, a compact and lightweight T-shaped pipe fitting 140 can be easily constructed.
Other operational effects of the pipe joint 140 are similar to those of the pipe joint 2 of the first embodiment, and therefore will not be described.

Sixth Embodiment
A sixth embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 27 to 29, a pipe joint 150 has a pipe joint body 151 instead of the pipe joint body 141 of the fifth embodiment.
In the pipe joint main body 151, the inner pipe portion 146 and the outer pipe portion 145 are formed of separate members, and the inner pipe portion 146 is held by the spacer portion 12. That is, the inner pipe portion 146 is supported in a state in which it is accommodated in the pipe space within the outer pipe portion 145 via the spacer portion 12.

As shown in Figure 28, the inner diameter D of the stopper portion 29 of the outer pipe portion 145 that corresponds to the socket end portion 21a is set to be equal to or greater than the height H of the inner pipe portion 146. That is, the relationship of inner diameter D ≥ height H is established. Note that height H is the length of the portion that corresponds to the vertical bar of the T in the T-shape formed by the inner pipe portion 146. This allows the inner pipe portion 146 to be accommodated in the intra-pipe space of the outer pipe portion 145 along arrow A from the socket end portion 21a of the socket portion 21, as shown in Figures 28 and 29.
The pipe joint 150 can be used in cases where the open ends 146a, 146b, 146c of the inner pipe portion 146 cannot be molded integrally using a die due to their structure, for example.

Furthermore, the pipe joint 150 does not require the joint support part 147 (see FIG. 26) that integrally connects the inner pipe part 146 and the outer pipe part 145. This makes it possible to prevent heat from the inner pipe part 146 from being transmitted to the outer pipe part 145 via the joint support part 147. As a result, the heat insulation of the pipe joint 150 can be improved.
When the inner pipe portion 146 or the outer pipe portion 145 is formed as a divided body, the relationship of inner diameter D≧height H does not need to be satisfied.

(First Modification)
A first modified example of the sixth embodiment will be described with reference to FIGS.
As shown in Figures 30 to 32, in the sixth embodiment, the pipe fitting 155 is configured so that the inner pipe portion 146 of the pipe fitting body 156 is accommodated in the outer pipe portion 145 from the receiving portion 21 corresponding to the receiving end portion 21b.
In the pipe joint main body 156, the inner pipe portion 146 and the outer pipe portion 145 are formed as separate members, and the inner pipe portion 146 is held by the spacer portions 12, 157. That is, the inner pipe portion 146 is supported in a state in which it is accommodated in the pipe space within the outer pipe portion 145 via the spacer portions 12, 157.

As shown in Figure 31, the inner diameter D of the stopper portion 29 of the receiving portion 21 corresponding to the receiving end 21b of the outer tube portion 145 is set to be equal to or greater than the length L of the inner tube portion 146. In other words, the relationship of inner diameter D ≥ length L is established. Note that length L is the length of the portion that corresponds to the cross bar of the T in the T-shape formed by the inner tube portion 146. This allows the inner tube portion 146 to be accommodated in the intra-tube space of the outer tube portion 145 along arrow B from the receiving end 21b of the receiving portion 21, as shown in Figures 31 and 32.

According to the pipe joint 155, it is possible to achieve the same effects as those of the pipe joint 150 of the sixth embodiment.
When the inner pipe portion 146 or the outer pipe portion 145 is formed as a divided body, the relationship of inner diameter D≧length L does not need to be satisfied.

As described above, in the first to sixth embodiments, pipe fittings have been exemplified, but the present invention is not limited to this, and may be applied to, for example, a piping structure. Below, piping structures will be described as the seventh and eighth embodiments with reference to Figures 33 to 36.

[Seventh embodiment]
A seventh embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 33 , the piping structure 160 includes a pipe joint 60 and a thermal insulation pipe 3 .
The pipe joint 60 has the same configuration as the pipe joint of the third modified example of the first embodiment in a state where the pipe joint 60 and the thermally insulated pipe 3 are combined. In this state, the pipe joint 60 includes an outer pipe portion 15, an inner pipe portion 16, and a spacer portion 61.

The spacer portion 61 has a second inner surface water stop portion 51a formed on the first inner surface water stop portion 12a and a second outer surface water stop portion 61a formed on the first outer surface water stop portion 12b. The second inner surface water stop portion 51a protrudes from the first inner surface water stop portion 12a toward the inside of the inner pipe portion 16 in a ring shape (including discontinuous ring shape) along the inner surface 16f. The second outer surface water stop portion 61a protrudes from the first outer surface water stop portion 12b in a ring shape (including discontinuous ring shape) along the inner surface 21c of the receiving portion 21 to the receiving end portion 21a. In this way, the second inner surface water stop portion 51a contacts the inner surface 16f of the inner pipe portion 16, and the second outer surface water stop portion 61a contacts the inner surface 21c of the receiving portion 21, thereby improving the sealing property of the hollow layer 36.

34 , however, the spacer portion 61 is attached to the thermally insulated pipe 3 side, not to the pipe fitting 60 side, before the pipe fitting 60 and the thermally insulated pipe 3 are combined. In other words, the spacer portion 61 is fitted to the end portion 3a of the thermally insulated pipe 3. In this state, the spacer portion 61 is inserted, together with the thermally insulated pipe 3, into the inside of the socket portion 21 (i.e., the opening portion 22) from the socket end portion 21a along the arrow C. As a result, the spacer portion 61 is held by the open ends 16a, 16b of the inner pipe portion 16 and the stopper portion 29.
In addition, a packing 14 may be provided between the spacer portion 61 and the thermal insulation pipe 3 .

[Eighth embodiment]
An eighth embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 35 , a piping structure 165 has a spacer portion 167 instead of the spacer portion 61 of the seventh embodiment, and is configured so that the hollow layer 36 of a pipe joint 166 is sealed by the spacer portion 167 and the end portion 3 a of the thermal insulation pipe 3 .

The spacer portion 167 is formed in an annular shape. The spacer portion 61 includes an annular inner wall 167b, an annular outer wall 167c, a fitting portion 167a provided between the inner wall 167b and the outer wall 167c, and an end portion 167d. The inner wall 167b is in contact with (fitted into) the inner surface 16f of the inner tube portion 16. The outer wall 167c is in contact with (fitted into) the outer surface 16h of the inner tube portion 16. The fitting portion 167a is a recess that is recessed toward the outside in the tube axis direction (the receiving end portion 21a, 21b side). The fitting portion 167a opens toward the inside in the tube axis direction. The fitting portion 167a is fitted into the open end portions 16a, 16b. The end portion 167d closes the fitting portion 167a from the outside in the tube axis direction. Opening ends 16a and 16b abut against end 167d.

In the pipe fitting 166, the open ends 16a and 16b of the inner pipe section 16 are located on the opposite side of the stopper section 29 from the receiving end 21a along the pipe axis direction. In other words, the open ends 16a and 16b of the inner pipe section 16 are located on the inside of the stopper section 29 in the pipe axis direction. The end 167d of the spacer section 167 is located flush with the stopper section 29.

In this state, the end 3a of the thermal insulation pipe 3 is joined to the end 167d of the spacer portion 167 and the inner surface 21c of the receiving portion 21 with adhesive 168. As a result, the piping structure 165 is configured so that the spacer portion 167 and the end 3a of the thermal insulation pipe 3 seal the hollow layer 36.

As shown in FIG. 36, before the pipe fitting 60 and the thermal insulation pipe 3 are assembled, the fitting portion 167a of the spacer portion 167 is fitted into the open ends 16a, 16b of the inner pipe portion 16. Furthermore, the end portion 3a of the thermal insulation pipe 3 is inserted into the inside (opening 22) of the receiving portion 21 from the receiving end portion 21a along the arrow D. At this time, adhesive 168 is applied in advance to at least one of the pipe fitting 166 and the thermal insulation pipe 3.

Then, as shown in FIG. 35, the end 3a of the inserted thermal insulation pipe 3 is kept bonded to the end 167d of the spacer portion 167 and the inner surface 21c of the receiving portion 21 with adhesive 168. This increases the production efficiency of the piping structure 165, and provides the pipe joint 166 of the piping structure 165 with a highly insulating hollow layer 36.

Furthermore, the end 167d of the spacer portion 167 can be used as the bonding surface for the end 3a of the thermal insulation pipe 3, and the bonding margin with the end face of the thermal insulation pipe 3 can be made larger than that of the open ends 16a and 16b. Therefore, by bonding the end face of the thermal insulation pipe 3 to the end 167d of the spacer portion 167 with the adhesive 168, it is possible to ensure watertightness between the thermal insulation pipe 3 and the inner pipe portion 16. This makes it possible to prevent cold water (wastewater) flowing through the thermal insulation pipe 3 and the inner pipe portion 16 from seeping into the hollow layer 36 of the pipe joint 166.
Here, the pipe joint 166 is formed by integrally molding the outer pipe portion 15 and the inner pipe portion 16 in a mold. For this reason, if the adhesive margin is increased at the open ends 16a, 16b of the inner pipe portion 16, the mold will not come off the pipe joint 166 when molding the pipe joint 166. Therefore, by attaching a spacer portion 167, which is a separate member, to the open ends 16a, 16b to increase the adhesive margin, it is possible to ensure watertightness.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

The outer tube parts 15, 145 of the first to eighth embodiments may be made of a transparent plastic material or the like. This makes it easier to visually check the state of internal liquid leakage in the pipe joints and piping structure from the outside, allowing early detection and preventing damage from spreading by taking prompt action such as repairs.

In addition, the components in the above embodiment may be replaced with well-known components as appropriate without departing from the spirit of the present invention, and the above-mentioned modifications may be combined as appropriate.

1, 160, 165 Piping structure 2, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 150, 155, 166 Pipe joint 3 Thermal insulation pipe 3a End of thermal insulation pipe 5 Outer pipe 6 Inner pipe (resin pipe)
7 Covering layer 12, 51, 56, 61, 71, 76, 81, 86, 91, 96, 101, 106, 111, 116, 142, 157, 167 Spacer portion 12a, 142a First inner surface water stopping portion (inner surface water stopping portion)
12b, 142b First outer surface water stopping portion (outer surface water stopping portion)
14, 107 Packing (annular foam)
15, 145 Outer tube portion 15d Inner surface of outer tube portion 16, 146 Inner tube portion 16a, 16b, 146a, 146b, 146c Open end portion (end portion)
16f: inner surface of inner pipe portion 16h: outer surface of inner pipe portion 21: socket portion 21c: inner surface of socket portion (inner surface of outer pipe portion)
22 Opening 28 Inner space of outer pipe 29 Stopper portion 36, 152 Hollow layer 51a, 71a, 81a, 96a, 101a, 111a, 116a Second inner water stop portion (inner water stop portion)
61a, 81b, 101b, 111b Second outer surface water stopping portion (outer surface water stopping portion)
86a, 92 Water stop portion 86b, 92a Inner surface of water stop portion (inner surface water stop portion)
86c, 92b Outer surface of water stopper part (outer surface water stopper part)
168 Adhesive

Claims (9)

A pipe joint for connecting a thermal insulation pipe,
an outer pipe portion into which the thermal insulation pipe is inserted and which has a plurality of openings having an inner diameter larger than an outer diameter of the thermal insulation pipe;
an inner tube portion disposed inside the outer tube portion and spaced apart from an inner surface of the outer tube portion;
a spacer portion that connects the inner pipe portion and the outer pipe portion and forms a hollow layer between the inner pipe portion and the outer pipe portion together with the inner pipe portion and the outer pipe portion;
A support portion disposed in the hollow layer;
Equipped with
an annular inner water stopper portion is provided on the inside of the spacer portion and is in contact with the inner surface, the outer surface or the end portion of the inner pipe portion over the entire circumference;
an annular outer surface water stopper portion is provided on the outside of the spacer portion and is in contact with the entire periphery of the inner surface of the outer pipe portion;
the support portion is a plate-like member extending in a tube axis direction of the outer tube portion and the inner tube portion, and is formed toward the openings ;
The inner pipe portion, the outer pipe portion, and the support portion are integrally formed with each other by injection molding of resin. A pipe joint for connecting a thermal insulation pipe,
an outer pipe portion into which the thermal insulation pipe is inserted, the outer pipe portion having a plurality of openings having an inner diameter larger than an outer diameter of the thermal insulation pipe, and having an L-shaped or T-shaped bent shape ;
an inner pipe portion disposed inside the outer pipe portion and spaced from the inner surface of the outer pipe portion , the inner pipe portion having an L-shaped or T-shaped bent shape ;
a spacer portion that connects the inner pipe portion and the outer pipe portion and forms a hollow layer between the inner pipe portion and the outer pipe portion together with the inner pipe portion and the outer pipe portion;
A support portion disposed in the hollow layer;
Equipped with
an annular inner water stopper portion is provided on the inside of the spacer portion and is in contact with the inner surface, the outer surface or the end portion of the inner pipe portion over the entire circumference;
an annular outer surface water stopper portion is provided on the outside of the spacer portion and is in contact with the entire periphery of the inner surface of the outer pipe portion;
The support portion is formed in a plate shape extending in a direction oblique to the tube axis direction of the outer tube portion and the inner tube portion, and is formed at a central position of the plurality of openings,
The inner pipe portion, the outer pipe portion, and the support portion are integrally formed with each other by injection molding of resin. the outer pipe portion includes a stopper portion having an inner diameter smaller than an outer diameter of the thermal insulation pipe,
3. A pipe joint according to claim 1, wherein an end of the inner pipe portion is located inside the stopper portion or on the same plane as the stopper portion. A pipe fitting according to any one of claims 1 to 3, wherein the spacer portion is located between the end of the inner pipe portion and the opening. A pipe fitting according to any one of claims 1 to 4, in which an annular foam is provided on the side of the opening of the spacer portion. A pipe joint for connecting a thermal insulation pipe,
an outer pipe portion into which the thermal insulation pipe is inserted and which has a plurality of openings having an inner diameter larger than an outer diameter of the thermal insulation pipe;
an inner tube portion disposed inside the outer tube portion and spaced apart from an inner surface of the outer tube portion;
a support portion that connects the inner pipe portion and the outer pipe portion and is disposed between the inner pipe portion and the outer pipe portion;
Equipped with
the support portion is a plate-like member extending in a tube axis direction of the outer tube portion and the inner tube portion, and is formed toward the openings ;
The inner pipe portion, the outer pipe portion, and the support portion are integrally formed with each other by injection molding of resin. A pipe joint for connecting a thermal insulation pipe,
an outer pipe portion into which the thermal insulation pipe is inserted, the outer pipe portion having a plurality of openings having an inner diameter larger than an outer diameter of the thermal insulation pipe, and having an L-shaped or T-shaped bent shape ;
an inner pipe portion disposed inside the outer pipe portion and spaced from the inner surface of the outer pipe portion , the inner pipe portion having an L-shaped or T-shaped bent shape ;
a support portion that connects the inner pipe portion and the outer pipe portion and is disposed between the inner pipe portion and the outer pipe portion;
Equipped with
The support portion is formed in a plate shape extending in a direction oblique to the tube axis direction of the outer tube portion and the inner tube portion, and is formed at a central position of the plurality of openings,
The inner pipe portion, the outer pipe portion, and the support portion are integrally formed with each other by injection molding of resin. the outer pipe portion includes a stopper portion having an inner diameter smaller than an outer diameter of the thermal insulation pipe,
an end of the inner tube portion is located inside the stopper portion or on the same plane as the stopper portion,
8. A pipe joint according to claim 6, wherein an end of the support portion is located more inward than an end of the inner pipe portion. 9. A pipe joint according to claim 1, wherein the outer pipe portion is transparent.

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