JP7477382B2 - Double Pipe Joint - Google Patents

Description

The present invention relates to a double pipe joint that connects two double pipes, each consisting of an outer pipe and an inner pipe.

When a fire brigade is fighting a fire, it is necessary to extend the fire hose from the fire engine to the fire site and ensure the delivery of extinguishing agent. The flow path used to transport the extinguishing agent is connected to the fire hose and the fire engine outlet, the fire hose and the spray nozzle, and to each other fire hoses via joints (connecting fittings) to prevent the extinguishing agent from leaking. Note that there are three types of connecting fittings sold in Japan: plug-in type, screw type, and twist type. Plug-in type connecting fittings are used by many fire brigades because they are simple in structure, lightweight, and easy to attach and detach.
In recent years, in addition to water, foam made by mixing water, chemicals, and air inside the fire engine has been used as the extinguishing agent transported from the fire engine. However, since this foam is mixed inside the fire engine, the mixture ratio cannot be changed arbitrarily with the spray nozzle.
On the other hand, if there are two flow paths from the fire engine to the spray nozzle, it is possible to transport the aqueous solution containing the air and the chemicals separately to the spray nozzle, and the mixture ratio can be changed at the spray nozzle. This means that when changing the foam mixture ratio, the nozzle head in charge of the spray nozzle does not need to give instructions to the fire engine operator, and the time lag between when the mixture ratio is changed in the fire engine and when the foam with the changed mixture ratio reaches the spray nozzle from the fire engine can be eliminated, resulting in a significant reduction in effort and time.
In addition, if multiple fire nozzles are connected by branching fire hoses from a single fire engine, the air-to-water mixture ratio can be changed freely for each nozzle depending on the fire situation, making the advantage of having two flow paths even greater.

To increase the number of flow paths to two, one method would be to simply use two fire hoses in parallel. However, if the fire engine is far from where the nozzle is to be used, multiple fire hoses must be connected in series. Also, if the fire hose is deployed using stairs, care must be taken to prevent it from turning around on the stairs or getting caught on the corners of buildings. For this reason, if the number of fire hoses is increased by connecting them in parallel, it takes twice as much time to start spraying water, and there is a possibility that firefighters may trip over the fire hoses and get injured.
For this reason, it is desirable that the two flow paths are contained in a single hose rather than being covered by two hoses, and that the connection between the two inner and outer connecting fittings be completed in a single operation.

FIG. 9 is a cross-sectional view of a hose having two flow paths that the present inventors have examined.
Figure 9(a) shows a structure in which two flow paths with circular cross sections are arranged in parallel inside a hose like an electric cord, Figure 9(b) shows a structure in which the cross section of the hose is divided in half to separate the flow paths, and Figure 9(c) shows a double pipe 2 with a coaxial double structure in which a smaller hose (inner pipe 2B) is placed inside a hose (outer pipe 2A).
In the structure shown in Fig. 9(a) and Fig. 9(b), or the structure shown in Fig. 9(c), when the outer hose is used as an air flow path, if the hose is damaged during use when the inside of the hose is filled with compressed air, there is a risk that the hose will burst due to the compressed air. On the other hand, in the structure shown in Fig. 9(c), if the inner hose is used as an air flow path and the outer hose is used as a water flow path, even if the inner hose is broken, the bursting will be contained within the outer hose, so safety can be ensured. Therefore, it is preferable that the hose (especially the fire hose) has a coaxial double structure as shown in Fig. 9(c), with the outer flow path being a flow path for liquids such as water and the inner flow path being a flow path for gases such as air.

Patent Document 1 discloses a double pipe joint structure that connects two double pipes in which an inner pipe, through which a high-pressure fluid circulates, is piped inside an outer pipe, through which a low-pressure fluid circulates, and in which the inner pipe and the outer pipe are formed integrally or separately and connected to each other by a connecting means.
Moreover, Patent Document 2 discloses a connecting fitting for a fire hose, which is composed of a fitting and a receiving fitting.

JP 2004-270928 A JP 2016-14477 A

In the case of a coaxial double pipe (double hose), the connection between the inner hose and the fitting is inside the outer hose. Therefore, it is required that the outer hose and the fitting can be securely connected after the inner hose and the fitting are securely connected in advance. In particular, when the double hose is a fire hose, the connection between the inner hose and the fitting, and the connection between the outer hose and the fitting must be crimped with wire or the like to prevent the hose and the fitting from coming loose.
In the double pipe joint structure of Patent Document 1, the inner pipe and the joint are manufactured integrally, such that the female joint portion is formed in the inner pipe of the double pipe, and therefore it cannot be applied to cases where the hose and the joint are manufactured separately.
Furthermore, the fire hose connecting fitting in Patent Document 2 is not for connecting a coaxial double-structure fire hose.
SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a double pipe joint that can easily connect double pipes to each other and can firmly connect the double pipe joint to the double pipe.

The double pipe joint 1 of the present invention described in claim 1 is a joint for connecting double pipes 2 consisting of an outer pipe 2A and an inner pipe 2B, and includes an outer pipe joint 10 consisting of an outer pipe male joint 10A and an outer pipe female joint 10B for connecting the outer pipes 2A together, and an inner pipe joint 20 consisting of an inner pipe male joint 20A and an inner pipe female joint 20B for connecting the inner pipes 2B together, and the outer pipe male joint 10A and the outer pipe female joint 10B have an inner pipe receiving portion 16 inside into which the inner pipe male joint 20A or the inner pipe female joint 20B is inserted, and an outer pipe joint connection portion for connecting with the mating outer pipe female joint 10B or the outer pipe male joint 10A is inserted at one end, and is connected by inserting the outer pipe 2A into or through the outer pipe 2A. The inner pipe male fitting 20A and the inner pipe female fitting 20B have an inner pipe fitting connection portion 23 at one end that connects to the mating inner pipe female fitting 20B or inner pipe male fitting 20A and an inner pipe connecting portion 23 at the other end that is inserted into the inner pipe 2B or the inner pipe 2B is inserted into and connected to the inner pipe 2B , and are provided with a protrusion protruding from the inner surface of the outer pipe fitting 10 or the outer surface of the inner pipe fitting 20, as well as a first stopper portion and a second stopper portion, and when the inner pipe fitting 20 is inserted into the inner pipe receiving portion 16 of the outer pipe fitting 10, the axial movement of the inner pipe fitting 20 is restricted by the protrusion abutting the first stopper portion and the second stopper portion .

The double pipe joint 1 of the present invention described in claim 2 is a joint for connecting double pipes 2 consisting of an outer pipe 2A and an inner pipe 2B, and includes an outer pipe joint 10 consisting of an outer pipe male joint 10A and an outer pipe female joint 10B for connecting the outer pipes 2A together, and an inner pipe joint 20 consisting of an inner pipe male joint 20A and an inner pipe female joint 20B for connecting the inner pipes 2B together, the outer pipe male joint 10A and the outer pipe female joint 10B having an inner pipe receiving portion 16 therein into which the inner pipe male joint 20A or the inner pipe female joint 20B is inserted, an outer pipe joint connecting portion at one end for connecting with the mating outer pipe female joint 10B or the outer pipe male joint 10A, and an outer pipe connecting portion 13 at the other end for connecting by inserting into or inserting the outer pipe 2A, The inner pipe male fitting 20A and the inner pipe female fitting 20B have an inner pipe fitting connection portion at one end that connects to the paired inner pipe female fitting 20B or inner pipe male fitting 20A, and an inner pipe connection portion 23 at the other end that is inserted into the inner pipe 2B or the inner pipe 2B to connect, and are equipped with a protrusion that protrudes from the outer surface of the inner pipe fitting 20 and has a bottomed hole 62, a through hole 61 that penetrates the outer pipe fitting 10 from the outer surface to the inner surface, and an insertion tool 63 that is inserted into the bottomed hole 62 and the through hole 61, and is characterized in that when the inner pipe fitting 20 is inserted into the inner pipe receiving portion 16 of the outer pipe fitting 10, the axial movement of the inner pipe fitting 20 is restricted by the insertion tool 63 being inserted into the bottomed hole 62 and the through hole 61.

The present invention described in claim 3 is characterized in that, in the double pipe joint 1 described in claim 1 or claim 2 , the inner pipe receiving portion 16 accommodates the entire inner pipe male joint 20A or the inner pipe female joint 20B.

The present invention described in claim 4 is characterized in that, in the double pipe joint 1 described in any one of claims 1 to 3, the outer pipe joint 10 is provided with a connection fixing portion 17 that serves both to fix the connection between the outer pipe male joint 10A and the outer pipe female joint 10B and to fix the connection between the inner pipe male joint 20A and the inner pipe female joint 20B.

The present invention as set forth in claim 5 is characterized in that in the double pipe joint 1 as set forth in any one of claims 1 to 4 , the inner pipe joint connecting portion is provided with tapers 25, 26 at the tip end .

The present invention described in claim 6 is characterized in that, in a double pipe joint 1 described in claim 1 or any one of claims 3 to 5 which cite claim 1, the outer pipe joint 10 has a rotation prevention portion which prevents rotation of the inner pipe joint 20 inserted into the inner pipe receiving portion 16 .

FIG. 1 is a diagram showing the structure of a double pipe joint according to an embodiment of the present invention; A diagram comparing the possibility of damage to double-walled pipes depending on the degree to which the inner pipe joint is fitted into the outer pipe joint. FIG. 13 is a diagram showing a first example of a method for fixing an inner pipe joint inserted into the inner pipe receiving portion. FIG. 11 is a view showing a second example of a method for fixing the inner pipe joint inserted into the inner pipe receiving portion. FIG. 11 is a view showing a third example of a method for fixing the inner pipe joint inserted into the inner pipe receiving portion. FIG. 11 is a side cross-sectional view showing a fourth example of a method for fixing the inner pipe joint inserted into the inner pipe receiving portion. Appearance photograph of a double pipe joint using the fixing method of the fourth example 11A to 11C are views showing a procedure for attaching a double pipe joint to a double pipe according to another embodiment of the present invention. Cross-section of a hose with two flow paths

A double pipe joint according to a first embodiment of the present invention is a joint for connecting double pipes consisting of outer pipes and inner pipes, and comprises an outer pipe joint consisting of an outer pipe male joint and an outer pipe female joint for connecting the outer pipes, and an inner pipe joint consisting of an inner pipe male joint and an inner pipe female joint for connecting the inner pipes, wherein the outer pipe male joint and the outer pipe female joint have an inner pipe receiving portion inside into which the inner pipe male joint or inner pipe female joint is inserted, and an outer pipe joint connection portion at one end for connecting to the mating outer pipe female joint or outer pipe male joint and an outer pipe connection portion at the other end for connecting by inserting the outer pipe into or inserting the outer pipe, and the inner pipe male joint and the inner pipe female joint have an inner pipe joint connection portion at one end for connecting to the mating inner pipe female joint or inner pipe male joint and an inner pipe connection portion at the other end for connecting by inserting the inner pipe into or inserting the inner pipe.
According to this embodiment, double pipes can be easily connected to each other. Also, when attaching a double pipe joint to a double pipe during manufacturing, the inner pipe and the inner pipe joint are crimped together, and the inner pipe joint is inserted into the outer pipe joint, and then the outer pipe and the outer pipe joint are crimped together, so that the double pipe and the double pipe joint can be firmly connected to each other.

A second embodiment of the present invention is a double pipe joint according to the first embodiment, in which the inner pipe receiving portion accommodates the entire inner pipe male joint or the inner pipe female joint.
According to this embodiment, when the double pipe joint falls to the ground, the inner pipe and the outer pipe can be prevented from being pinched between the ground and the inner pipe joint and being damaged.

A third embodiment of the present invention is a double pipe joint according to the first or second embodiment, in which the outer pipe joint is provided with a connection fixing portion that serves both to fix the connection between the outer pipe male joint and the outer pipe female joint, and to fix the connection between the inner pipe male joint and the inner pipe female joint.
According to this embodiment, when connecting or disconnecting the double pipes, the operations related to fixing or releasing the connection between the outer pipe male joint and the outer pipe female joint, and fixing or releasing the connection between the inner pipe male joint and the inner pipe female joint can be performed all at once. Also, by providing the connection fixing part on the outer pipe joint, the connection state can be easily visually confirmed.

A fourth embodiment of the present invention is a double pipe joint according to any one of the first to third embodiments, wherein the inner pipe joint connecting portion is tapered at its tip.
According to this embodiment, when the inner pipe female joint is inserted into the inner pipe male joint, they are guided so that their axes coincide with each other.

A fifth embodiment of the present invention is a double pipe joint according to any one of the first to fourth embodiments, which is provided with a protrusion protruding from the inner surface of the outer pipe joint or the outer surface of the inner pipe joint, and a first stopper portion and a second stopper portion, and when the inner pipe joint is inserted into the inner pipe receiving portion of the outer pipe joint, the axial movement of the inner pipe joint is restricted by the protrusion abutting against the first stopper portion and the second stopper portion.
According to this embodiment, the relative position of the inner pipe joint with respect to the outer pipe joint can be fixed.

A sixth embodiment of the present invention is a double pipe joint according to any one of the first to fifth embodiments, wherein the outer pipe joint has a rotation prevention portion that prevents rotation of the inner pipe joint inserted into the inner pipe receiving portion.
According to this embodiment, rotation of the inner pipe joint relative to the outer pipe joint is suppressed, so that it is possible to prevent damage to the inner surface of the outer pipe joint due to rotation of the inner pipe joint.

A seventh embodiment of the present invention is a double pipe joint according to any one of the first to fourth embodiments, comprising a protrusion protruding from the outer surface of the inner pipe joint and provided with a bottomed hole, a through hole provided in the outer pipe joint penetrating from the outer surface to the inner surface, and an inserting tool inserted into the bottomed hole and the through hole, and when the inner pipe joint is inserted into the inner pipe receiving portion of the outer pipe joint, the axial movement of the inner pipe joint is restricted by the inserting tool being inserted into the bottomed hole and the through hole.
According to this embodiment, the relative position of the inner pipe joint with respect to the outer pipe joint can be fixed.

Hereinafter, a double pipe joint according to one embodiment of the present invention will be described.
Fig. 1 shows the structure of a double pipe joint according to this embodiment, Fig. 1(a) is a perspective view and Fig. 1(b) is a side view. Note that only half of the outer pipe joint is shown in order to show the internal structure.
The double pipe joint 1 connects together double pipes 2 having a coaxial double structure composed of an outer pipe 2A and an inner pipe 2B as shown in Fig. 9(c). The double pipe 2 is, for example, a fire hose whose main material is resin, rubber, or the like and has flexibility.
The double pipe joint 1 includes a substantially cylindrical outer pipe joint 10 and an inner pipe joint 20. The inner diameter of the outer pipe joint 10 is larger than the outer diameter of the inner pipe joint 20, and the inner pipe joint 20 is disposed inside the outer pipe joint 10. The double pipe joint 1 can be made of metal or resin.
The outer pipe joint 10 used to connect the outer pipes 2A together consists of a pair of an outer pipe male joint 10A which is a spigot and an outer pipe female joint 10B which is a socket. The inner pipe joint 20 used to connect the inner pipes 2B together consists of a pair of an inner pipe male joint 20A which is a spigot and an inner pipe female joint 20B which is a socket.

The outer pipe male joint 10A has a male outer pipe joint connection portion 11 at one end as an outer pipe joint connection portion that connects to the outer pipe female joint 10B, and an outer pipe connection portion 13 at the other end as a connection port that connects to the outer pipe 2A of the first double pipe 2. The outer surface of the outer pipe connection portion 13 is provided with sawtooth irregularities.
The outer pipe female joint 10B has at one end a female outer pipe joint connection portion 12 having a larger diameter than the male outer pipe joint connection portion 11 as an outer pipe joint connection portion for connecting to the outer pipe male joint 10A, and at the other end an outer pipe connection portion 13 for connecting to the outer pipe 2A of the second double pipe 2. The outer surface of the outer pipe connection portion 13 is provided with sawtooth-like irregularities. In addition, in the outer pipe female joint 10B, a rubber band 14 is attached in a ring shape to the outer surface on the one end side, and a rubber packing 15 is attached to the inner surface.
The inner surface of the female outer pipe joint connection portion 12 has a cross-sectional surface (cross-sectional surface perpendicular to the axial direction) that is a perfect circle. The outer pipe male joint 10A and the outer pipe female joint 10B are configured so that their central axes coincide with each other when connected. Therefore, when inserting the outer pipe male joint 10A into the outer pipe female joint 10B, it is not necessary to align the central axis of the cross-sectional circle in the rotational direction, and the outer pipe male joint 10A and the outer pipe female joint 10B can be quickly connected.

The inner pipe male joint 20A has a male inner pipe joint connecting portion 21 at one end as an inner pipe joint connecting portion that connects to the inner pipe female joint 20B, and an inner pipe connecting portion 23 at the other end as a connection port that connects to the inner pipe 2B of the first double pipe 2. The outer surface of the inner pipe connecting portion 23 is provided with sawtooth irregularities.
The inner pipe female joint 20B has a female inner pipe joint connection part 22 having a larger diameter than the male inner pipe joint connection part 21 as an inner pipe joint connection part that connects to the inner pipe male joint 20A at one end, and an inner pipe connection part 23 that connects to the inner pipe 2B of the second double pipe 2 at the other end. The outer surface of the inner pipe connection part 23 is provided with sawtooth-shaped irregularities. The inner pipe female joint 20B also has a seal part 24 near the opening on the one end side. The seal part 24 is, for example, an O-ring, a U-packing, a V-packing, a Y-packing, or an X-packing. The seal part 24 is in close contact with the outer surface of the inner pipe male joint 20A inserted into the inner pipe female joint 20B. This provides a seal in the circumferential direction, and it is possible to reliably prevent the fluid flowing through the inner pipe 2B from leaking to the outer pipe 2A side.
The inner surface of the female inner pipe fitting connection portion 22 has a cross section that is a perfect circle. The inner pipe male fitting 20A and the inner pipe female fitting 20B are configured so that their central axes coincide with each other when connected. Therefore, when inserting the inner pipe male fitting 20A into the inner pipe female fitting 20B, it is not necessary to align the central axis of the cross-sectional circle in the rotational direction, and the inner pipe male fitting 20A and the inner pipe female fitting 20B can be quickly connected.
Further, a tapered outer surface of the tip of the male inner pipe joint connection portion 21 is provided with a tapered end 25, and a tapered inner surface of the tip of the female inner pipe joint connection portion 22 is provided with a tapered end 26. As a result, even if the central axis of the inner pipe female joint 20B and the central axis of the inner pipe male joint 20A are misaligned when the inner pipe male joint 20A is inserted into the inner pipe female joint 20B, the axes are guided to coincide with each other, so that the inner pipe male joint 20A and the inner pipe female joint 20B can be smoothly connected.

Further, the outer pipe male joint 10A and the outer pipe female joint 10B each have an inner pipe receiving portion 16 into which the inner pipe male joint 20A or the inner pipe female joint 20B is inserted. In this embodiment, the inner pipe receiving portion 16 that receives the inner pipe male joint 20A is formed inside the outer pipe male joint 10A, and the inner pipe receiving portion 16 that receives the inner pipe female joint 20B is formed inside the outer pipe female joint 10B. It is also possible to form the inner pipe receiving portion 16 that receives the inner pipe female joint 20B inside the outer pipe male joint 10A, and the inner pipe receiving portion 16 that receives the inner pipe male joint 20A inside the outer pipe female joint 10B.
The inner surface of the inner pipe receiving portion 16 has a cross section that is a perfect circle. In addition, when the inner pipe fitting 20 is inserted into the inner pipe receiving portion 16, the central axis of the outer pipe fitting 10 and the central axis of the inner pipe fitting 20 coincide with each other. Therefore, when inserting the inner pipe fitting 20 into the outer pipe fitting 10, it is not necessary to align the central axis of the cross-sectional circle in the rotational direction.

As an example of the procedure for attaching the double pipe fitting 1 to the end of the double pipe 2 during manufacturing, first, the positional relationship between the two is shifted so that the inner pipe 2B is pulled out from the outer pipe 2A of the double pipe 2, and the inner pipe connection portion 23 of the inner pipe fitting 20 is inserted into the end of the inner pipe 2B of the double pipe 2, and then crimped from above using a metal ring, wire, hose band, or the like.
Next, the inner pipe joint 20 to which the inner pipe 2B is connected is inserted into the inner pipe receiving portion 16 from the opening on the other end side of the outer pipe joint 10.
Next, the inner pipe joint 20 inserted into the inner pipe receiving portion 16 is fixed so as not to move more than a predetermined amount in the axial direction. The fixing method will be described in detail later.
Finally, the outer pipe 2A and the inner pipe 2B are returned to their original positions, and the outer pipe connection part 13 of the outer pipe joint 10 is inserted into the end of the outer pipe 2A of the double pipe 2, and then crimped from above using a metal ring, wire, hose band, etc. In this state, the axial position of the outer pipe connection part 13 and the axial position of the inner pipe connection part 23 are overlapped.
In this way, when attaching the double pipe joint 1 to the double pipe 2, the inner pipe 2B and the inner pipe joint 20 are crimped together, and the inner pipe joint 20 is inserted into the outer pipe joint 10, and then the outer pipe 2A and the outer pipe joint 10 are crimped together, so that the double pipe 2 and the double pipe joint 1 can be firmly connected. Therefore, there is no need to worry about the double pipe joint 1 coming off even if an external force such as pulling, bending, or twisting is applied.
In this embodiment, the connection between the double pipe 2 and the double pipe joint 1 is an external mounting type in which the pipes are crimped from the outside, but it can also be an internal mounting type in which the pipes are crimped from the inside. In the internal mounting type, the end of the inner pipe 2B is inserted into the inner pipe connecting portion 23, and the end of the outer pipe 2A is inserted into the outer pipe connecting portion 13.

Here, Figure 2 is a diagram comparing the possibility of damage to a double pipe depending on the degree to which the inner pipe joint is accommodated in the outer pipe joint, with Figure 2(a) showing a double pipe joint in which the entire inner pipe joint is accommodated in the outer pipe joint, and Figure 2(b) showing a double pipe joint in which only a portion of the inner pipe joint is accommodated in the outer pipe joint.
As shown in Figure 2 (b), in a state where the inner pipe receiving portion 16 is smaller than the inner pipe male fitting 20A or the inner pipe female fitting 20B and the inner pipe connection portion 23 protrudes from the outer pipe fitting 10, when the double pipe fitting 1 falls to the ground 3, the inner pipe 2B and the outer pipe 2A will be pinched between the inner pipe fitting 20 and the ground 3, and the inner pipe 2B and the outer pipe 2A may be damaged.
On the other hand, in a stored state in which the inner pipe fitting 20 does not protrude from the outer pipe fitting 10 as shown in Figure 2 (a), when the double pipe fitting 1 falls to the ground 3, the inner pipe 2B and the outer pipe 2A will not be pinched between the inner pipe fitting 20 and the ground 3, thereby preventing damage to the inner pipe 2B and the outer pipe 2A by the inner pipe fitting 20.
Therefore, it is preferable that the size of the inner pipe receiving portion 16 be equal to or larger than the size of the inner pipe male fitting 20A or the inner pipe female fitting 20B, and that the inner pipe receiving portion 16 accommodates the entire inner pipe male fitting 20A or the inner pipe female fitting 20B.

When connecting the double pipes 2 together, one half of the double pipe joint 1 is joined to the other half of the mating double pipe joint 1. In this embodiment, as shown in FIG. 1, the connection method of the double pipe joint 1 is a plug-in type (Machino type). The double pipe joint 1 has a push ring 17A and a protrusion 17B on the outer pipe male joint 10A as a connection fixing portion 17, and has a claw 17C on the outer pipe female joint 10B. The claw 17C is movable in a direction perpendicular to the central axis of the outer pipe female joint 10B. On the other hand, the inner pipe joint 20 does not have a connection fixing portion 17.
When joining the two halves of the double pipe joint 1, the outer pipe male joint 10A is inserted into the outer pipe female joint 10B, and at the same time, the inner pipe male joint 20A is inserted into the inner pipe female joint 20B. When the outer pipe male joint 10A is inserted into the outer pipe female joint 10B to a predetermined position, the protrusion 17B and the claw 17C engage with each other, and the connection between the outer pipe male joint 10A and the outer pipe female joint 10B is fixed (locked). Also, since the inner pipe joint 20 accommodated in the inner pipe receiving portion 16 as described above is fixed so as not to move in the axial direction, the connection between the outer pipe male joint 10A and the outer pipe female joint 10B is fixed, and therefore the connection between the inner pipe male joint 20A and the inner pipe female joint 20B is indirectly fixed.
When the double pipes 2 are to be separated, the claw 17C is pushed up above the protrusion 17B by operating the push ring 17A to release the connection between the outer pipe male joint 10A and the outer pipe female joint 10B. This simultaneously releases the connection between the inner pipe male joint 20A and the inner pipe female joint 20B. The two halves of the double pipe joint 1 are then separated from each other.
In this way, the double pipes 2 can be easily connected to each other by using the double pipe joint 1. Furthermore, when connecting or separating the double pipes 2 to each other, the connection between the outer pipe male joint 10A and the outer pipe female joint 10B and the connection between the inner pipe male joint 20A and the inner pipe female joint 20B can be fixed or released all at once by operating the connection fixing portion 17 provided on the outer pipe joint 10, so that the double pipes 2 can be quickly connected or separated to each other. Furthermore, by providing the connection fixing portion 17 only on the outer pipe joint 10, the connection state can be easily visually confirmed.

In the above, the connection method of the double pipe 2 has been described as a plug-in type, but it can also be a screw type or twist type. However, since the plug-in type is the most widely distributed in Japan, it is preferable to use the plug-in type in consideration of the commonality of parts with conventional plug-in type joints. In addition, the double pipe joint 1 of the present invention can also be connected to a joint provided on a single pipe with only one flow path.

As described above, the inner pipe fitting 20 inserted into the inner pipe receiving portion 16 of the outer pipe fitting 10 is fixed so as not to move in the axial direction. Below are four examples of methods for fixing the positional relationship between the outer pipe fitting 10 and the inner pipe fitting 20.

Figure 3 shows a first example of a method for fixing an inner pipe fitting inserted into an inner pipe receiving portion, where Figure 3(a) is an exploded oblique view, Figure 3(b) is a side cross-sectional view in the fixed state, and Figure 3(c) is a front view showing the other end of a double pipe fitting consisting of an outer pipe male fitting and an inner pipe male fitting in the fixed state.
The inner pipe male fitting 20A and the inner pipe female fitting 20B have a plurality of plate-shaped protrusions 31 as protrusions protruding from the outer surface. The protrusions 31 are provided at a predetermined interval in the circumferential direction at a position between the male inner pipe fitting connection portion 21 or the female inner pipe fitting connection portion 22 and the inner pipe connection portion 23, and their upper surfaces contact the inner surface of the outer pipe fitting 10. In addition, the heights of the protrusions 31 are equal. By making the heights of the protrusions 31 equal, the central axis of the outer pipe fitting 10 and the central axis of the inner pipe fitting 20 can be aligned when the inner pipe fitting 20 is inserted into the inner pipe receiving portion 16.
A plurality of protrusions 31 are provided so that the inner pipe joint 20 does not become biased inside the outer pipe joint 10, but if there are too many, there is a possibility that the flow of the fluid may be obstructed. Therefore, the number of protrusions 31 per inner pipe male joint 20A or the inner pipe female joint 20B is preferably three or four. In this embodiment, the inner pipe male joint 20A and the inner pipe female joint 20B are provided with three protrusions 31 each, which are arranged at 120 degree intervals in the circumferential direction.

The outer pipe male joint 10A and the outer pipe female joint 10B have a step 32 on the inner surface as a first stopper portion. The step 32 is provided around the circumference, and the inner diameter of the portion where the step 32 is provided is smaller than the outer diameter of the portion of the inner pipe joint 20 where the protruding piece 31 is provided. Therefore, when the inner pipe joint 20 is inserted from the opening on the other end side of the outer pipe joint 10, the position where one end of the protruding piece 31 abuts against the step 32 is the maximum insertion position of the inner pipe joint 20. The position where the step 32 is provided is set taking into consideration the lengths of the outer pipe joint 10 and the inner pipe joint 20, the insertion amount of the inner pipe joint 20 into the outer pipe joint 10, etc.
Further, on the inner surfaces of the outer pipe male joint 10A and the outer pipe female joint 10B, a groove 34 is provided in the circumferential direction on the other end side of the step 32. The distance between the step 32 and the groove 34 is set to be slightly larger than the length of the protrusion 31 of the inner pipe joint 20.
After the inner pipe joint 20 is inserted into the outer pipe joint 10 to the maximum insertion position, the retaining ring 33, which is the second stopper portion, is inserted along the outer surface of the inner pipe joint 20 from the opening on the other end side of the outer pipe joint 10 and fitted into the groove 34. As a result, the retaining ring 33 and the other end of the protruding piece 31 are in close proximity to each other, and the inner pipe joint 20 is prevented from moving backward by the other end of the protruding piece 31 abutting against the retaining ring 33. In this way, by sandwiching the protruding piece 31 (protruding part) between the step 32 (first stopper portion) and the retaining ring 33 (second stopper portion), the axial movement of the inner pipe joint 20 accommodated in the outer pipe joint 10 is restricted and it cannot move more than a predetermined amount. That is, the relative position of the inner pipe joint 20 with respect to the outer pipe joint 10 is fixed. In this example, the retaining ring 33 is a C-shaped retaining ring, but it can also be a concentric retaining ring or a retaining ring made of a C-shaped spring material.

As shown in Figures 3(b) and (c), a first fluid 4 (e.g., air) flows through the inner pipe joint 20, and a second fluid 5 (e.g., water) flows through the outer pipe joint 10. At this time, the second fluid 5 passes between the protrusions 31 and between the retaining ring 33 and the outer surface of the inner pipe joint 20. It is preferable that the cross section of the protrusions 31 be wing-shaped, which minimizes resistance to the flow.

In addition, when the inner pipe joint 20 is not fixed with screws from the outside of the outer joint 10, the outer pipe male joint 10A and the outer pipe female joint 10B have linear grooves 35 therein as rotation prevention sections. The linear grooves 35 are linear grooves extending in the axial direction from the opening on the other end side to just before the step 32, and three linear grooves, the same number as the number of protrusions 31, are provided at 120 degree intervals in the circumferential direction.
When inserting the inner pipe joint 20 into the outer pipe joint 10, the protrusion 31 is inserted into the linear groove 35. As a result, the inner pipe joint 20 inserted into the outer pipe joint 10 has the protrusion 31 fitted into the linear groove 35, preventing rotation of the inner pipe joint 20 relative to the outer pipe joint 10. By restricting rotation of the inner pipe joint 20 relative to the outer pipe joint 10, damage to the inner surface of the outer pipe joint 10 due to rotation of the inner pipe joint 20 can be prevented.
If no rotation preventing portion is provided, the inner pipe joint 20 can rotate so as to allow twisting of the inner pipe 2B and the outer pipe 2A relative to the outer pipe joint 10. Whether or not to provide a rotation preventing portion is determined based on the application of the double pipe 2, etc.

The protrusion 31 may be provided on the inner surface of the outer pipe joint 10, instead of the inner pipe joint 20. In this case, for example, a groove corresponding to the protrusion 31 of the outer pipe joint 10 is provided in the axial direction on one end side of the inner pipe joint 20, and the end point of the groove (the other end side) is made the first stopper portion. A step may be provided at the end point of the groove.
During assembly, the inner pipe joint 20 is inserted so that its groove aligns with the protruding piece 31 of the outer pipe joint 10, and slid until the protruding piece 31 abuts against the end of the groove. Then, a retaining ring 33, which is a second stopper portion, is inserted into the outer pipe joint 10 from one end side of the inner pipe joint 20.

Figure 4 is a diagram showing a second example of a method for fixing an inner pipe fitting inserted into an inner pipe receiving portion, where Figure 4(a) is an exploded oblique view, Figure 4(b) is a side cross-sectional view in the fixed state, and Figure 4(c) is a front view showing the other end of a double pipe fitting consisting of an outer pipe male fitting and an inner pipe male fitting in the fixed state.
During manufacture, a first retaining plate 41, a spacing retaining member 42, and a second retaining plate 41 are fitted in that order from the inner pipe connection portion 23 side onto the outer surfaces of the inner pipe male joint 20A and the inner pipe female joint 20B.
The retaining plate 41 is circular and has an inner ring 41A that is in close contact with the outer surface of the inner pipe joint 20, and an outer ring 41B that is in contact with the inner surface of the outer pipe joint 10. A predetermined gap is provided between the inner ring 41A and the outer ring 41B, and the inner ring 41A and the outer ring 41B are connected by three inner and outer ring connection parts 41C. The fluid flowing through the outer pipe 2A passes between the inner ring 41A and the outer ring 41B.
The spacing member 42 is cylindrical and adheres closely to the outer surface of the inner pipe joint 20. The spacing member 42 may adhere closely to the inner surface of the inner pipe joint 20. The thickness of the spacing member 42 is set to be equal to or smaller than the inner ring 41A so as not to impede the flow of fluid. The thickness of the spacing member 42 may be equal to or smaller than the outer ring 41B.
An outwardly protruding step 43 is provided in the circumferential direction on the outer surfaces of the inner pipe male joint 20A and the inner pipe female joint 20B, and the first retaining plate 41 cannot advance beyond the step 43. Therefore, the first retaining plate 41 is positioned by abutting against the step 43. Also, one end of the spacing member 42 is positioned so as to abut against the first retaining plate 41, and the second retaining plate 41 is positioned so as to abut against the other end of the spacing member 42. As a result, the inner pipe joint 20 has a protruding portion made up of two retaining plates 41 on its outer surface.

The outer pipe male joint 10A and the outer pipe female joint 10B have a step 44 on their inner surfaces as a first stopper portion. The step 44 is provided in the circumferential direction.
The inner diameter of the portion where the step 44 is provided is smaller than the outer diameter of the portion of the inner pipe joint 20 where the retaining plate 41 is provided. Therefore, when the inner pipe joint 20 is inserted from the opening on the other end side of the outer pipe joint 10, the position where the first retaining plate 41 abuts on the first stopper portion is the maximum insertion position of the inner pipe joint 20. The position where the step 44 is provided is set taking into consideration the lengths of the outer pipe joint 10 and the inner pipe joint 20, the insertion amount of the inner pipe joint 20 into the outer pipe joint 10, etc.
Further, on the inner surfaces of the outer pipe male joint 10A and the outer pipe female joint 10B, a groove 45 is provided in the circumferential direction on the other end side of the step 44. The distance between the step 44 and the groove 45 is set to be slightly larger than the distance between the holding plates 41.
After the inner pipe joint 20 is inserted into the outer pipe joint 10 to the maximum insertion position, the retaining ring 46, which is the second stopper portion, is inserted along the outer surface of the inner pipe joint 20 from the opening on the other end side of the outer pipe joint 10 and fitted into the groove 45. This brings the retaining ring 46 and the second holding plate 41 into close proximity. The inner pipe joint 20 cannot move back beyond the retaining ring 46 because the second holding plate 41 abuts against the retaining ring 46. In this example, the retaining ring 46 is a C-shaped retaining ring, but it can also be a concentric retaining ring or a retaining ring made of a C-shaped spring material. Also, a screw can be set from the outside of the outer pipe joint 10 to prevent the retaining ring 46 from coming off.
In this way, by sandwiching the two retaining plates 41 (protruding portions) between the step 44 (first stopper portion) and the retaining ring 46 (second stopper portion), the axial movement of the inner pipe fitting 20 housed in the outer pipe fitting 10 is restricted and the inner pipe fitting 20 cannot move beyond a predetermined amount. In other words, the relative position of the inner pipe fitting 20 with respect to the outer pipe fitting 10 is fixed.

As shown in Figures 4(b) and (c), a first fluid 4 (e.g., air) flows through the inner pipe joint 20, and a second fluid 5 (e.g., water) flows through the outer pipe joint 10. At this time, the second fluid 5 passes between the retaining ring 46 and the outer surface of the inner pipe joint 20, and between the inner ring 41A and the outer ring 41B.

In addition, the double pipe joint 1 in this example does not have a rotation prevention portion, and the retaining plate 41, which is a protruding portion, is not fixed in the rotation direction around the axis center, so the inner pipe joint 20 can rotate relative to the outer pipe joint 10 in a manner that allows twisting of the inner pipe 2B and the outer pipe 2A.

Figure 5 is a diagram showing a third example of a method for fixing an inner pipe fitting inserted into an inner pipe receiving portion, where Figure 5(a) is an exploded oblique view, Figure 5(b) is a side cross-sectional view in the fixed state, and Figure 5(c) is a front view of the ring material.
In this example, the outer pipe male joint 10A is composed of a first outer pipe male joint 10Aa having a male outer pipe joint connection portion 11, and a second outer pipe male joint 10Ab having an outer pipe connection portion 13. The outer pipe female joint 10B is composed of a first outer pipe female joint 10Ba having a female outer pipe joint connection portion 12, and a second outer pipe female joint 10Bb having an outer pipe connection portion 13.
The inner pipe male joint 20A is made up of a first inner pipe male joint 20Aa having a male inner pipe joint connection portion 21, a second inner pipe male joint 20Ab having an inner pipe connection portion 23, and an annular ring material 51 connecting the first inner pipe male joint 20Aa and the second inner pipe male joint 20Ab. The inner pipe female joint 20B is made up of a first inner pipe female joint 20Ba having a female inner pipe joint connection portion 22, a second inner pipe female joint 20Bb having an inner pipe connection portion 23, and an annular ring material 51 connecting the first inner pipe female joint 20Ba and the second inner pipe female joint 20Bb.

The end of the first inner pipe male joint 20Aa or the first inner pipe female joint 20Ba opposite to the end where the inner pipe joint connecting portion is provided is inserted approximately halfway into the ring material 51 from one side, and the end of the second inner pipe male joint 20Ab or the second inner pipe female joint 20Bb opposite to the end where the inner pipe connecting portion 23 is provided is inserted approximately halfway from the other side. As a result, the inner pipe male joint 20A formed by integrating the first inner pipe male joint 20Aa and the second inner pipe male joint 20Ab, and the inner pipe female joint 20B formed by integrating the first inner pipe female joint 20Ba and the second inner pipe female joint 20Bb have the ring material 51 as a protrusion on the outer surface.
The outer surface of the ring material 51 contacts the inner surface of the outer pipe joint 10, and the inner surface is in close contact with the outer surface of the inner pipe joint 20. In addition, a long hole 51A through which a fluid flows is formed between the outer surface and the inner surface.

In this example, the first stopper portion is an end face 52A at one end of the first outer pipe male joint 10Aa and an end face 52B at one end of the first outer pipe female joint 10Ba. The second outer pipe male joint 10Ab and the second outer pipe female joint 10Bb have a step 53 on their inner surfaces as a second stopper portion. The step 53 is provided around the circumference, and the inner diameter of the portion where the step 53 is provided is smaller than the outer diameter of the portion of the inner pipe joint 20 where the ring material 51 is provided.
As an example of a procedure for attaching the double pipe fitting 1 to the end of the double pipe 2 during manufacturing, etc., first, the inner pipe 2B of the double pipe 2 is crimped to the inner pipe connection portion 23 of the second inner pipe male fitting 20Ab or the second inner pipe female fitting 20Bb.
Next, the second inner pipe male joint 20Ab or the second inner pipe female joint 20Bb to which the inner pipe 2B is connected is passed through the second outer pipe male joint 10Ab or the second outer pipe female joint 10Bb, and inserted approximately halfway from one side into the ring material 51. Also, the first inner pipe male joint 20Aa or the first inner pipe female joint 20Ba is inserted approximately halfway from the other side of the ring material 51. The ring material 51 and the first inner pipe male joint 20Aa or the first inner pipe female joint 20Ba may be integrally formed in advance.
Next, one end of the first outer pipe male joint 10Aa or the first outer pipe female joint 10Ba is inserted into the second outer pipe male joint 10Ab or the second outer pipe female joint 10Bb so as to cover the first inner pipe male joint 20Aa or the first inner pipe female joint 20Ba. In this state, the ring material 51 is positioned so as to be sandwiched between the end face 52A or the end face 52B and the step 53, and therefore, by the ring material 51 abutting against the end face 52A or the end face 52B and the step 53, the axial movement of the inner pipe joint 20 housed in the outer pipe joint 10 is restricted and it cannot move more than a predetermined amount. In other words, the relative position of the inner pipe joint 20 with respect to the outer pipe joint 10 is fixed.
Next, the outer pipe 2A of the double pipe 2 is crimped to the outer pipe connecting portion 13 of the second outer pipe male joint 10Ab or the second outer pipe female joint 10Bb. As a result, one half of the double pipe joint 1 consisting of the outer pipe joint 10 and the inner pipe joint 20 is attached to the end of the double pipe 2.

As shown in Figures 5(b) and (c), a first fluid 4 (e.g., air) flows through the inner pipe joint 20, and a second fluid 5 (e.g., water) flows through the outer pipe joint 10. At this time, the second fluid 5 passes through the long hole 51A.

In addition, the double pipe joint 1 in this example does not have a rotation prevention portion, and the protruding ring material 51 is not fixed in the rotation direction around the axis, so the inner pipe joint 20 can rotate relative to the outer pipe joint 10 in a manner that allows twisting of the inner pipe 2B and the outer pipe 2A.

Fig. 6 is a side cross-sectional view showing a fourth example of a method for fixing an inner pipe joint inserted into an inner pipe receiving portion. Fig. 7 is a photograph of the appearance of a double pipe joint using the fourth example of the fixing method, in which Fig. 7(a) shows a state before the inner pipe joint is inserted into the outer pipe joint, and Fig. 7(b) shows a state after the inner pipe joint is inserted into the outer pipe joint.
In this example, similar to the first example described above, the inner pipe male joint 20A and the inner pipe female joint 20B have a plurality of plate-shaped protrusions 31 as protrusions protruding from the outer surface. The protrusions 31 are provided at a predetermined interval (e.g., 120 degree intervals) in the circumferential direction at a position between the male inner pipe joint connection portion 21 or the female inner pipe joint connection portion 22 and the inner pipe connection portion 23, and the upper surface contacts the inner surface of the outer pipe joint 10. The protrusions 31 are equal in height. Each protrusion 31 is provided with a bottomed hole 62.
The outer pipe male joint 10A and the outer pipe female joint 10B have a plurality of through holes 61 penetrating from the outer surface to the inner surface. The through holes 61 are provided at predetermined intervals in the circumferential direction in correspondence with the protrusions 31 (protrusions) at positions between the male outer pipe joint connection portion 11 or the female outer pipe joint connection portion 12 and the outer pipe connection portion 13.
The positions at which the through hole 61 and the bottomed hole 62 are provided are set taking into consideration the lengths of the outer pipe joint 10 and the inner pipe joint 20, the insertion amount of the inner pipe joint 20 into the outer pipe joint 10, etc.

When assembling, the inner pipe joint 20 is inserted into the outer pipe joint 10, the position of the through hole 62 of the outer pipe joint 10 is aligned with the position of the bottom hole 61, and then an insertion tool 63 such as a screw is passed through the through hole 62 and the bottom hole 61 from the outside of the outer pipe joint 1 to secure it in place.
As a result, the inner pipe joint 20 is connected to the outer pipe joint 10 via the protruding piece 31, and the axial movement of the inner pipe joint 20 housed in the inner pipe receiving portion 16 is restricted so that it cannot move beyond a predetermined distance. In other words, the relative position of the inner pipe joint 20 with respect to the outer pipe joint 10 is fixed.

In addition, in this example, the double pipe joint 1 has the inner pipe joint 20 connected to the outer pipe joint 10 via the protrusion 31, so that the inner pipe joint 20 is prevented from rotating relative to the outer pipe joint 10.

Next, a double pipe joint according to another embodiment of the present invention will be described. Note that the same reference numerals are used to designate the same functional members as those in the above-mentioned embodiment, and the description thereof will be omitted.
FIG. 8 is a diagram showing a procedure for attaching a double pipe joint to a double pipe according to this embodiment.
As described in the above embodiment, when attaching the double pipe joint 1 to the end of the double pipe 2 during manufacturing, etc., first the inner pipe 2B of the double pipe 2 is crimped to the inner pipe connection portion 23 of the inner pipe joint 20, and then the outer pipe 2A of the double pipe 2 is crimped to the outer pipe connection portion 13 of the outer pipe joint 10.
In this case, if the overall length of the double pipe 2 is short, the lengths of the outer pipe 2A and the inner pipe 2B may be the same, since the positional relationship between the two can be shifted so that the inner pipe 2B can be pulled out from the outer pipe 2A relatively easily when crimping and connecting the inner pipe 2B to the inner pipe connecting portion 23. However, if the overall length of the double pipe 2 is long, it takes time and effort to shift the positional relationship between the outer pipe 2A and the inner pipe 2B.
Therefore, in this embodiment, the inner pipe 2B is made longer than the outer pipe 2A so that the portion of the inner pipe 2B that crimps the hose protrudes outward from the inner pipe 2A. Also, the overall length of the outer pipe joint 10 is made longer than in the above embodiment in accordance with the amount of protrusion of the inner pipe 2B.

As an example of the procedure for attaching a double pipe fitting 1 to the end of a double pipe 2 during manufacturing, etc., first, the outer pipe 2A is passed over the outside of the inner pipe 2B, and the end of the inner pipe 2B is made to protrude beyond the end of the outer pipe 2A (Figure 8 (a)).
Next, the inner pipe connecting portion 23 of the inner pipe joint 20 is inserted into the end portion of the inner pipe 2B of the double pipe 2 (FIG. 8(b)).
Next, the inner pipe 2B is crimped to the inner pipe joint 20 using a crimping material 60A such as a metal ring, wire, or hose band (FIG. 8(c)).
Next, the outer pipe connecting portion 13 of the outer pipe joint 10 is inserted into the end portion of the outer pipe 2A of the double pipe 2 (FIG. 8(d)).
Finally, the outer pipe 2A is crimped to the outer pipe joint 10 using a crimping material 60B such as a metal ring, wire, or hose band (FIG. 8(e)). In this state, the axial position of the outer pipe connecting portion 13 and the axial position of the inner pipe connecting portion 23 are not overlapped.
In this way, the double pipe joint 1 according to this embodiment can be attached to the end of the double pipe 2 without changing the positional relationship between the outer pipe 2A and the inner pipe 2B. Therefore, this is particularly effective when the double pipe 2 has a long overall length, such as when the double pipe 2 is a fire hose with a general overall length of 20 m.

1 Double pipe joint 2 Double pipe 2A Outer pipe 2B Inner pipe 10 Outer pipe joint 10A Outer pipe male joint 10B Outer pipe female joint 11 Male outer pipe joint connection part (outer pipe joint connection part)
12 Female outer pipe joint connection part (outer pipe joint connection part)
13 Outer pipe connection portion 16 Inner pipe receiving portion 17 Connection fixing portion 20 Inner pipe joint 20A Inner pipe male joint 20B Inner pipe female joint 21 Male inner pipe joint connection portion (inner pipe joint connection portion)
22 Female inner pipe joint connection part (inner pipe joint connection part)
23 Inner pipe connection portion 25, 26 Taper 31 Projection piece (projection portion)
32, 44 Step (first stopper portion)
33, 46 Retaining ring (second stopper portion)
35 Straight groove (rotation prevention part)
41 Retaining plate (protruding part)
51 Ring material (protruding part)
52A, 52B End surface (first stopper portion)
53 Step (second stopper portion)

Claims (6)

A joint for connecting double pipes each consisting of an outer pipe and an inner pipe,
an outer pipe joint consisting of an outer pipe male joint and an outer pipe female joint for connecting the outer pipes to each other;
an inner pipe joint consisting of an inner pipe male joint and an inner pipe female joint for connecting the inner pipes together;
The outer pipe male joint and the outer pipe female joint have an inner pipe receiving portion into which the inner pipe male joint or the inner pipe female joint is inserted, an outer pipe joint connection portion at one end that connects to the mating outer pipe female joint or the outer pipe male joint, and an outer pipe connection portion at the other end that is inserted into the outer pipe or the outer pipe is inserted to connect,
The inner pipe male joint and the inner pipe female joint have an inner pipe joint connection portion at one end that is connected to the mating inner pipe female joint or the inner pipe male joint, and an inner pipe connection portion at the other end that is inserted into the inner pipe or the inner pipe is inserted into the inner pipe to connect,
a protrusion protruding from an inner surface of the outer pipe joint or an outer surface of the inner pipe joint;
A first stopper portion and a second stopper portion,
A double pipe joint, characterized in that when the inner pipe joint is inserted into the inner pipe receiving portion of the outer pipe joint, the axial movement of the inner pipe joint is restricted by the protrusion abutting the first stopper portion and the second stopper portion . A joint for connecting double pipes each consisting of an outer pipe and an inner pipe,
an outer pipe joint consisting of an outer pipe male joint and an outer pipe female joint for connecting the outer pipes to each other;
an inner pipe joint consisting of an inner pipe male joint and an inner pipe female joint for connecting the inner pipes together;
The outer pipe male joint and the outer pipe female joint have an inner pipe receiving portion into which the inner pipe male joint or the inner pipe female joint is inserted, an outer pipe joint connection portion at one end that connects to the mating outer pipe female joint or the outer pipe male joint, and an outer pipe connection portion at the other end that is inserted into the outer pipe or the outer pipe is inserted to connect,
The inner pipe male joint and the inner pipe female joint have an inner pipe joint connection portion at one end that is connected to the mating inner pipe female joint or the inner pipe male joint, and an inner pipe connection portion at the other end that is inserted into the inner pipe or the inner pipe is inserted into the inner pipe to connect,
a protruding portion protruding from an outer surface of the inner pipe joint and having a bottomed hole;
a through hole provided in the outer pipe joint so as to penetrate from an outer surface to an inner surface;
An insertion tool is provided that is inserted into the bottomed hole and the through hole,
A double pipe joint, characterized in that when the inner pipe joint is inserted into the inner pipe receiving portion of the outer pipe joint, the axial movement of the inner pipe joint is restricted by inserting the insertion tool into the bottomed hole and the through hole. 3. The double pipe joint according to claim 1, wherein the inner pipe receiving portion accommodates the entire inner pipe male joint or the entire inner pipe female joint. A double pipe joint as described in any one of claims 1 to 3, characterized in that the outer pipe joint is provided with a connection fixing portion that serves to fix the connection between the outer pipe male joint and the outer pipe female joint and to fix the connection between the inner pipe male joint and the inner pipe female joint. 5. The double pipe joint according to claim 1, wherein the inner pipe joint connecting portion is tapered at a tip end. A double pipe joint as described in claim 1 , or any one of claims 3 to 5 that cite claim 1, characterized in that the outer pipe joint has a rotation prevention portion that prevents rotation of the inner pipe joint inserted into the inner pipe receiving portion.