Pipe joint structure and method for constructing pipe joint structure

Abstract

A pipe joint of the present disclosure comprises: an outer joint pipe having a first inner peripheral surface portion on one side in an axial direction and a second inner peripheral surface portion on the other side in the axial direction, and allowing an outer peripheral surface of a pipe to be fitted onto the first inner peripheral surface portion from the one side in the axial direction; an inner joint pipe having a first outer peripheral surface portion on the one side in the axial direction that is fitted onto an inner peripheral surface of the pipe from the other side in the axial direction, a second outer peripheral surface portion that is fitted onto the second inner peripheral surface portion from the other side in the axial direction, and an end portion on the other side in the axial direction that is connected to a fluid device; an annular seal member that is installed on the first outer peripheral surface portion and seals a gap between the first outer peripheral surface portion and the inner peripheral surface of the pipe; a first restriction portion that restricts the pipe from moving toward the one side in the axial direction relative to the first inner peripheral surface portion by fitting the outer peripheral surface of the pipe on the first inner peripheral surface portion; and a second restriction portion that restricts the inner joint pipe from moving toward the other side in the axial direction relative to the second inner peripheral surface portion by fitting the second outer peripheral surface portion on the second inner peripheral surface portion.

Description

Pipe joint structure and construction method for pipe joint structure

[0001] The present disclosure relates to a pipe joint structure and a method for installing the pipe joint structure.

[0002] A pipe fitting described in Patent Document 1 is known as a connection structure for connecting piping such as tubes to flow paths of fluid devices such as fluidic equipment in manufacturing equipment in various technical fields such as semiconductor manufacturing and medical / pharmaceutical manufacturing. The pipe fitting in Patent Document 1 includes an inner ring attached to the inner periphery of the end of the tube, a fitting body attached to the outer periphery of the end of the tube, and a union nut with female threads that is tightened onto a male thread formed on the outer periphery of the fitting body.

[0003] When connecting a tube to the pipe fitting, the worker presses the inner ring onto the inner periphery of the end of the tube, attaches the fitting body to the outer periphery of the end of the tube, and then tightens the female thread of the union nut onto the male thread of the fitting body. This ensures sealing performance between the fitting body and the tube and prevents the end of the tube from slipping out of the fitting body.

[0004] Japanese Patent Application Laid-Open No. 2021-195959

[0005] In the above-mentioned pipe joint, a tool such as a wrench is required to tighten the union nut to the joint body. Therefore, in a narrow working space, it may not be possible to tighten the union nut using a tool. In addition, torque management is required to ensure that the tightening amount of the union nut is within an appropriate range. This torque management requires skill, which creates the problem of limiting the number of workers who can tighten the union nut.

[0006] An object of the present disclosure is to provide a pipe joint structure that allows pipes to be easily connected without using tools, and a method for installing the pipe joint structure.

[0007] (1) A pipe joint structure of the present disclosure is a pipe joint structure for connecting a pipe to a flow path formed in a fluid device, comprising: an outer joint pipe having a first inner circumferential surface portion on one axial side and a second inner circumferential surface portion on the other axial side, with an outer circumferential surface of the pipe being fitted onto the first inner circumferential surface portion from the one axial side; and a pipe joint pipe having a first outer circumferential surface portion on the one axial side that is fitted onto the inner circumferential surface of the pipe from the other axial side and a second outer circumferential surface portion on the other axial side that is fitted onto the second inner circumferential surface portion of the outer joint pipe from the other axial side, with an end on the other axial side being connected to the fluid device. an inner joint pipe connected to a seat; an annular sealing member provided on the first outer peripheral surface portion of the inner joint pipe and sealing between the first outer peripheral surface portion and the inner peripheral surface of the piping; a first limiting portion configured to limit relative movement of the piping to one axial side with respect to the first inner peripheral surface portion by fitting the outer peripheral surface of the piping into the first inner peripheral surface portion of the outer joint pipe; and a second limiting portion configured to limit relative movement of the inner joint pipe to the other axial side with respect to the second inner peripheral surface portion by fitting the second outer peripheral surface portion of the inner joint pipe into the second inner peripheral surface portion of the outer joint pipe.

[0008] According to the pipe coupling structure of the present disclosure, by inserting a pipe relatively from one axial side into the inner circumferential side of the outer joint pipe, the outer circumferential surface of the pipe is fitted into the first inner circumferential surface portion of the outer joint pipe. As a result, the first limiting portion can limit relative movement of the pipe toward the one axial side with respect to the first inner circumferential surface portion of the outer joint pipe. In this state, by inserting the inner joint pipe relatively from the other axial side into the inner circumferential side of the outer joint pipe, the first outer circumferential surface portion of the inner joint pipe is fitted into the inner circumferential surface of the pipe, and the second outer circumferential surface portion of the inner joint pipe is fitted into the second inner circumferential surface portion of the outer joint pipe. As a result, the gap between the first outer circumferential surface portion of the inner joint pipe and the inner circumferential surface of the pipe is sealed by the seal member, and the second limiting portion can limit relative movement of the inner joint pipe toward the other axial side with respect to the second inner circumferential surface portion of the outer joint pipe. Therefore, the worker can easily connect the piping to the pipe joint structure without using any tools by simply inserting the piping relatively to the inner periphery of the outer joint pipe from one axial side, and then inserting the inner joint pipe relatively to the inner periphery of the outer joint pipe from the other axial side.

[0009] (2) In the pipe joint structure of (1), it is preferable that the first limiting portion has an engaging protrusion provided on one of the first inner peripheral surface portion of the outer joint pipe and the outer peripheral surface of the piping, and an engaging groove provided on the other, and the relative movement of the piping is limited by the engaging protrusion engaging with the engaging groove. In this case, since the first limiting portion is configured so that the engaging protrusion engages with the engaging groove, it is possible to reliably limit the relative movement of the piping with respect to the outer joint pipe.

[0010] (3) In the pipe joint structure of (2), the engagement groove is preferably located on the other axial side of the seal member. For example, if the engagement groove of the first limiting portion is formed to penetrate the pipe in the thickness direction, fluid in the pipe may pass through the engagement groove between the pipe and the outer joint pipe and leak to one axial side of the outer joint pipe. Therefore, a seal structure that suppresses fluid leakage must be provided in addition to the seal member. However, in the pipe joint structure of (3), the engagement groove is located on the other axial side of the seal member that seals between the pipe and the outer joint pipe, so that the seal member can suppress fluid in the pipe from leaking from the engagement groove to one axial side of the outer joint pipe. This eliminates the need for a separate seal structure, simplifying the configuration of the pipe joint structure.

[0011] (4) In the pipe joint structure of any one of (1) to (3), the second limiting portion preferably has a hook portion integrally formed on one of the second inner peripheral surface portion of the outer joint pipe and the second outer peripheral surface portion of the inner joint pipe, and a hook groove formed on the other, and the relative movement of the inner joint pipe is restricted by the hook portion being hooked into the hook groove. In this case, since the second limiting portion is configured so that the hook portion is hooked into the hook groove, the relative movement of the inner joint pipe with respect to the outer joint pipe can be reliably restricted. Furthermore, since the hook portion is integrally formed on the second outer peripheral surface portion of the inner joint pipe or the second inner peripheral surface portion of the outer joint pipe, the configuration of the pipe joint structure can be simplified.

[0012] (5) In the pipe coupling structure of any one of (1) to (3), it is preferable that the second limiting portion has a locking portion provided on the outer coupling pipe as a separate body and capable of protruding radially inward beyond the second inner circumferential surface portion, and a locking groove provided on the second outer circumferential surface portion of the inner coupling pipe, and the relative movement of the inner coupling pipe is restricted by the locking portion protruding radially inward and locking into the locking groove. In this case, since the second limiting portion is configured so that the locking portion is hooked into the locking groove, the relative movement of the inner coupling pipe with respect to the outer coupling pipe can be reliably restricted.

[0013] (6) A construction method for a pipe joint structure according to the present disclosure is a construction method for connecting a pipe to any one of the pipe joint structures according to (1) to (5) for connecting the pipe to a flow path formed in a fluid device, the construction method including, in this order, the steps of: inserting the pipe relative to the inner periphery of the outer joint pipe from one axial side of the outer joint pipe and fitting the outer periphery of the pipe to the first inner periphery of the outer joint pipe; and inserting the inner joint pipe relative to the inner periphery of the outer joint pipe from the other axial side of the outer joint pipe and fitting the first outer periphery of the inner joint pipe to the inner periphery of the pipe and fitting the second outer periphery of the inner joint pipe to the second inner periphery of the outer joint pipe. The construction method for a pipe joint structure according to the present disclosure provides the same effects as those of the above-described pipe joint structure.

[0014] According to the present disclosure, piping can be easily connected to a pipe joint structure without using tools.

[0015] FIG. 1 is a perspective view showing a pipe joint structure according to a first embodiment. FIG. 2 is a view taken along arrow A in FIG. 1. FIG. 3 is a cross-sectional view taken along line B-O-C in FIG. 2. FIG. 4 is a perspective view of the outer joint pipe as seen from one axial side. FIG. 5 is a perspective view of the outer joint pipe as seen from the other axial side. FIG. 6 is a perspective view of the inner joint pipe. FIG. 7 is a cross-sectional perspective view showing the first limiting portion. FIG. 8 is a perspective view showing the large groove portion of the hooking groove of the second limiting portion. FIG. 9 is an explanatory diagram of a construction method for the pipe joint structure of FIG. 1. FIG. 10 is an explanatory diagram of a construction method for the pipe joint structure of FIG. 1. FIG. 11 is an explanatory diagram of a construction method for the pipe joint structure of FIG. 1. FIG. 12 is an explanatory diagram of a construction method for the pipe joint structure of FIG. 1. FIG. 13 is an explanatory diagram of a construction method for the pipe joint structure of FIG. 1. FIG. 14 is an explanatory diagram of a construction method for the pipe joint structure of FIG. 1. FIG. 15 is a perspective view showing a pipe joint structure according to a second embodiment. Fig. 16 is a view of the outer joint pipe of the second embodiment as seen from the other axial side. Fig. 17 is a view showing a state in which the guided portion of the locking rod has slid along the guide surface from the state shown in Fig. 16. Fig. 18 is an explanatory view of a construction method for the pipe joint structure of Fig. 15. Fig. 19 is an explanatory view of a construction method for the pipe joint structure of Fig. 15. Fig. 20 is an explanatory view of a construction method for the pipe joint structure of Fig. 15. Fig. 21 is an explanatory view of a construction method for the pipe joint structure of Fig. 15. Fig. 22 is a perspective view showing a pipe joint structure according to a third embodiment. Fig. 23 is a view of the outer joint pipe of the third embodiment as seen from the other axial side. Fig. 24 is a view of the outer joint pipe of the third embodiment as seen from the bottom of Fig. 23. Fig. 25 is a perspective view showing the locking rod of the third embodiment. Fig. 26 is a view showing a state in which the locking rod has moved downward from the state shown in Fig. 23. Fig. 27 is a sectional perspective view showing the inner joint pipe of the third embodiment. 28 and 29 are cross-sectional perspective views showing modified examples of the first restricting portion.

[0016] Next, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. [First Embodiment] <Configuration of Pipe Joint Structure> Fig. 1 is a perspective view showing a pipe joint structure 1 according to a first embodiment. Fig. 2 is a view seen from the arrow A in Fig. 1. Fig. 3 is a cross-sectional view taken along the line B-O-C in Fig. 2. In Figs. 1 to 3, the pipe joint structure 1 is used, for example, in a hydrogen carrier production apparatus, to connect a synthetic resin tube (piping) 72 to a flow path 71 of a fluid device 70 through which a corrosive fluid (transport fluid) flows. The pipe joint structure 1 includes an outer joint pipe 2, an inner joint pipe 3, and a seal member 4.

[0017] Hereinafter, in this disclosure, the direction along the axis O of the pipe joint structure 1 is the axial direction of the pipe joint structure 1, and will be simply referred to as the "axial direction." For convenience, the right side of Fig. 3 will be referred to as the "one axial side," and the left side of Fig. 3 will be referred to as the "other axial side." Furthermore, the direction perpendicular to the axis O is the radial direction of the pipe joint structure 1, and will be simply referred to as the "radial direction." The direction rotating around the axis O is the circumferential direction of the pipe joint structure 1, and will be simply referred to as the "circumferential direction."

[0018] The outer joint pipe 2 is formed into a cylindrical shape from a synthetic resin material such as PVC, PP, PE, or fluororesin (PFA or PTFE). The outer peripheral surface 22 of the outer joint pipe 2 has the same diameter throughout the axial direction. The inner peripheral surface 21 of the outer joint pipe 2 has a first inner peripheral surface portion 211 formed on one axial side and a second inner peripheral surface portion 212 formed on the other axial side. The second inner peripheral surface portion 212 has a larger diameter than the first inner peripheral surface portion 211. The outer peripheral surface 72b of the end of the tube 72 is fitted into the first inner peripheral surface portion 211 from one axial side.

[0019] Recesses 213 are formed in the first inner circumferential surface portion 211. The recesses 213 are formed in pairs at equal intervals (180° intervals) in the circumferential direction of the first inner circumferential surface portion 211 (see FIG. 2). Each recess 213 is formed over the entire axial length of the first inner circumferential surface portion 211. The bottom surface of each recess 213 is formed flush with the second inner circumferential surface portion 212.

[0020] Fig. 4 is a perspective view of the outer joint pipe 2 as viewed from one axial side. Fig. 5 is a perspective view of the outer joint pipe 2 as viewed from the other axial side. In Figs. 2 to 5, slits 23 are formed on both circumferential sides of each recess 213. Each slit 23 is cut from the end face of the outer joint pipe 2 on the other axial side to a midpoint on one axial side (a midpoint of the recess 213). Each slit 23 divides the second inner circumferential surface portion 212 in the circumferential direction.

[0021] The outer joint pipe 2 has a flexible piece 24 between a pair of circumferentially adjacent slits 23 in each slit 23. Each flexible piece 24 has a base end 24a on one axial side and a tip end 24b on the other axial side. The tip end 24b is capable of flexible deformation in the radial direction with the base end 24a as a fulcrum.

[0022] Figure 6 is a perspective view showing the inner joint pipe 3. In Figures 3 and 6, a communication passage 3a through which the transferred fluid flows is formed so as to penetrate the inner joint pipe 3 in the axial direction. In this embodiment, the transferred fluid is a corrosive fluid, so the inner joint pipe 3 is made of a corrosion-resistant material (for example, fluororesin or titanium palladium). The inner joint pipe 3 includes an annular portion 31 at one end in the axial direction, and a cylindrical portion 32 extending from the inner peripheral end of the annular portion 31 to one side in the axial direction.

[0023] The outer peripheral surface 31b of the annular portion 31 has a larger diameter than the outer peripheral surface 22 of the outer joint pipe 2. The annular portion 31 is connected to the fluid device 70 so that the communication passage 3a communicates with a flow path 71 of the fluid device 70. The inner peripheral surface 31a of the annular portion 31 has approximately the same diameter as the inner peripheral surface of the flow path 71.

[0024] The inner circumferential surface 33 of the cylindrical portion 32 has a constant diameter throughout the axial direction and is the same diameter as the inner circumferential surface 31a of the annular portion 31. The outer circumferential surface 34 of the cylindrical portion 32 has a first outer circumferential surface portion 341 formed on one axial side and a second outer circumferential surface portion 342 formed on the other axial side. The second outer circumferential surface portion 342 has a larger diameter than the first outer circumferential surface portion 341. The first outer circumferential surface portion 341 is fitted onto the inner circumferential surface 72a of the end of the tube 72 from one axial side. The second outer circumferential surface portion 342 is fitted onto the second inner circumferential surface portion 212 of the outer joint pipe 2 from the other axial side.

[0025] The inner peripheral surface 33 of the cylindrical portion 32 further has an annular tapered surface 343 formed between the first outer peripheral surface portion 341 and the second outer peripheral surface portion 342. The tapered surface 343 is inclined so as to gradually increase in diameter from one axial end to the other axial end.

[0026] The seal member 4 is an annular member that prevents the transferred fluid from leaking between the first outer circumferential surface portion 341 of the inner joint pipe 3 and the inner circumferential surface 72a of the end of the tube 72. The seal member 4 is made of a corrosion-resistant material, similar to the inner joint pipe 3. The seal member 4 in this embodiment is, for example, an O-ring.

[0027] The seal member 4 is provided on the first outer peripheral surface portion 341 of the inner joint pipe 3. Specifically, an annular groove 344 is formed at one axial end of the first outer peripheral surface portion 341, and the seal member 4 is fitted into this groove 344 and fixed. As described above, by fitting the first outer peripheral surface portion 341 of the inner joint pipe 3 into the inner peripheral surface 72a of the end of the tube 72, the outer peripheral surface of the seal member 4 comes into close contact with the inner peripheral surface 72a of the end of the tube 72. As a result, the seal member 4 seals between the first outer peripheral surface portion 341 of the inner joint pipe 3 and the inner peripheral surface 72a of the end of the tube 72.

[0028] The tube 72 may tend to expand radially outward from the state shown in Figure 3 due to the fluid pressure of the transported fluid or thermal expansion. In this case, the outer peripheral surface 72b of the tube 72 is fitted into the first inner peripheral surface portion 211 of the outer joint pipe 2, so the outer joint pipe 2 can restrict the expansion of the tube 72. This can prevent a gap from being formed between the inner joint pipe 3 (cylindrical portion 32) and the tube 72. As a result, it is possible to prevent a portion of the seal member 4 in the recessed groove 344 from protruding into the gap or a reduction in the radial crushing allowance of the seal member 4, thereby effectively preventing a deterioration in the sealing performance of the seal member 4.

[0029] The pipe joint structure 1 further includes a first limiting portion 5. Fig. 7 is a cross-sectional perspective view showing the first limiting portion 5. In Figs. 3 and 7, the first limiting portion 5 has a pair of engaging protrusions 51 and a pair of engaging grooves 52. The pair of engaging protrusions 51 are integrally formed on the first inner circumferential surface portion 211 of the outer joint pipe 2. The pair of engaging grooves 52 are formed on the outer circumferential surface 72b of the end portion of the tube 72. In the state shown in Fig. 3, the pair of engaging grooves 52 are located on the other axial side of the seal member 4.

[0030] The pair of engaging protrusions 51 are provided at equal intervals (180° intervals) in the circumferential direction of the first inner circumferential surface portion 211. Each engaging protrusion 51 is located between a pair of flexible pieces 24 in the circumferential direction. In this embodiment, each engaging protrusion 51 is located at an intermediate position between the pair of flexible pieces 24. Each engaging protrusion 51 protrudes radially inward from the first inner circumferential surface portion 211. Each engaging protrusion 51 is formed, for example, in a triangular shape in cross section. Each engaging protrusion 51 has a tapered surface 51a and an engaging surface 51b.

[0031] The tapered surface 51a is inclined so that the radially inward protrusion length of the engagement protrusion 51 gradually increases from one axial end to the other axial end. The engagement surface 51b is a stepped surface formed between the other axial end of the tapered surface 51a and the first inner circumferential surface portion 211, and is formed perpendicular to the first inner circumferential surface portion 211.

[0032] A pair of engagement grooves 52 are formed at equal circumferential intervals (180° apart) on the outer peripheral surface 72b of the end of the tube 72 (see also Figure 9). The engagement protrusion 51 fits into and engages with each engagement groove 52. For this reason, the engagement groove 52 is formed to be large enough to fit the entire engagement protrusion 51. In this embodiment, each engagement groove 52 is a circumferentially long hole formed by penetrating the tube 72 in the thickness direction. The circumferential length of each engagement groove 52 is greater than the circumferential length of the engagement protrusion 51. The side surface on the other axial side of each engagement groove 52 is an engaged surface 52a with which the engagement surface 51b of the engagement protrusion 51 engages.

[0033] With the outer peripheral surface 72b of the end of the tube 72 fitted into the first inner peripheral surface portion 211 of the outer joint pipe 2, the engaging protrusions 51 are fitted into each engaging groove 52, and the engaging surfaces 51b of the engaging protrusions 51 are engaged with the engaged surfaces 52a of the engaging grooves 52. This engagement restricts relative movement of the tube 72 to one axial side with respect to the first inner peripheral surface portion 211 of the outer joint pipe 2. Therefore, by fitting the outer peripheral surface 72b of the end of the tube 72 into the first inner peripheral surface portion 211 of the outer joint pipe 2, the first restricting portion 5 can prevent the tube 72 from slipping out to one axial side with respect to the first inner peripheral surface portion 211 of the outer joint pipe 2.

[0034] 3 , 5 and 6 , the pipe joint structure 1 further includes a second limiting portion 6. The second limiting portion 6 has a pair of hooking portions 61 and a pair of hooking grooves 62. The pair of hooking portions 61 are integrally formed on the second inner circumferential surface portion 212 of the outer joint pipe 2. The pair of hooking grooves 62 are formed on the second outer circumferential surface portion 342 of the inner joint pipe 3.

[0035] The pair of hook portions 61 are provided at equal intervals (180° intervals) in the circumferential direction of the second inner circumferential surface portion 212. In this embodiment, each hook portion 61 is provided on the inner circumferential surface (second inner circumferential surface portion 212) on the tip end portion 24b side of the flexible piece 24. The tip end portion 24b of the flexible piece 24 is bent and deformed in the radial direction, so that the hook portion 61 can be displaced in the radial direction relative to the outer joint pipe 2.

[0036] The hook portion 61 is formed in a hook shape and has a first plate portion 61 a that protrudes radially inward from the second inner circumferential surface portion 212, and a second plate portion 61 b ​​that extends axially from the protruding end of the first plate portion 61 a to one side.

[0037] A pair of hook grooves 62 are formed at equal intervals (180° intervals) in the circumferential direction on the second outer peripheral surface portion 342 of the inner joint pipe 3. Each hook groove 62 has a large groove portion 62a and a small groove portion 62b that communicates with the large groove portion 62a. The large groove portion 62a is dug from the second outer peripheral surface portion 342 toward the radially inward side of the inner joint pipe 3. The large groove portion 62a is formed to a size that allows the entire hook portion 61 to fit therein. In this embodiment, the large groove portion 62a is, for example, a recessed groove that is long in the circumferential direction. The circumferential length of the large groove portion 62a is greater than the circumferential length of the hook portion 61. The axial length of the large groove portion 62a is greater than the axial length of the hook portion 61.

[0038] The small groove 62b is dug from the bottom side of one axial side of the large groove 62a toward that side. The small groove 62b is formed to a size that allows the second plate portion 61b of the hook portion 61 to fit into it. The circumferential length of the small groove 62b is the same as the circumferential length of the large groove 62a. The second plate portion 61b of the hook portion 61 fits into the small groove 62b, causing the hook portion 61 to be caught in the hook groove 62.

[0039] 3, with the second outer peripheral surface portion 342 of the inner joint pipe 3 fitted into the second inner peripheral surface portion 212 of the outer joint pipe 2, each hook portion 61 of the second limiting portion 6 is fitted into the large groove portion 62a of the hook groove 62. When the inner joint pipe 3 moves relatively to the other axial side with respect to the outer joint pipe 2 from this state, the second plate portion 61b of the hook portion 61 is hooked into the small groove portion 62b.

[0040] This restricts relative movement of the inner joint pipe 3 toward the other axial side with respect to the second inner circumferential surface portion 212 of the outer joint pipe 2. Therefore, by fitting the second outer circumferential surface portion 342 of the inner joint pipe 3 into the second inner circumferential surface portion 212 of the outer joint pipe 2, the second restricting portion 6 can restrain the inner joint pipe 3 from slipping out toward the other axial side with respect to the second inner circumferential surface portion 212 of the outer joint pipe 2.

[0041] Fig. 8 is a perspective view showing the large groove portion 62a of the hook groove 62 of the second restricting portion 6. In Fig. 3 and Fig. 8, a tapered surface 62c is formed on each circumferential side of each large groove portion 62a (see also Fig. 6). The tapered surface 62c is inclined so that the groove depth gradually increases from the open end on each circumferential side of the large groove portion 62a toward the bottom surface.

[0042] 3 , when the worker rotates the outer joint pipe 2 relative to the inner joint pipe 3 toward one circumferential side or the other circumferential side, the second plate portion 61b of the hook portion 61 comes into contact with the tapered surface 62c of the large groove portion 62a. When the worker further rotates the outer joint pipe 2 from this state, the hook portion 61 moves along the tapered surface 62c to the second outer peripheral surface portion 342 while being displaced radially outward relative to the outer joint pipe 2. As a result, the hook portion 61 comes out of the hook groove 62. When the worker moves the outer joint pipe 2 relative to the inner joint pipe 3 from this state toward the other axial side, the outer joint pipe 2 can be relatively separated from the inner joint pipe 3.

[0043] <Construction method of pipe joint structure> Next, a construction method for connecting the tube 72 to the pipe joint structure 1 of this embodiment will be described. Figures 9 to 14 are explanatory views of the construction method. First, as shown in Figure 9, an operator inserts the end of the tube 72 relatively from one axial side of the outer joint pipe 2 into the inner circumferential side of the outer joint pipe 2. Then, the end of the tube 72 moves relatively to the other axial side while part of its outer circumferential surface 72b is fitted into the first inner circumferential surface portion 211 of the outer joint pipe 2.

[0044] Here, "relatively inserting" one tube into the other tube includes any of the following cases D, E, and F (same below). D: When one tube is inserted into another tube by moving the other tube while the other tube is stationary. E: When one tube is inserted into another tube by moving the other tube while the other tube is stationary. F: When one tube is inserted into another tube by moving both the one tube and the other tube.

[0045] When the end of the tube 72 moves relatively toward the other axial side within the outer joint pipe 2, as shown by the solid line in Fig. 10, the end face 72c of the tube 72 abuts against the tapered surface 51a of the engaging protrusion 51 on the outer joint pipe 2 side. From this state, when the worker presses the tube 72 relatively toward the other axial side with respect to the outer joint pipe 2, the end of the tube 72 elastically deforms radially inward, and the end face 72c of the tube 72 moves relatively toward the other axial side along the tapered surface 51a and rides over the engaging protrusion 51 as shown by the two-dot chain line in Fig. 10.

[0046] From this state, when the worker further pushes the tube 72 relatively toward the other axial side, as shown in Figure 11, the engaging protrusion 51 fits into the engaging groove 52 of the first restricting portion 5, and the outer peripheral surface 72b of the end of the tube 72 fits over the entire first inner peripheral surface portion 211 of the outer joint pipe 2. As the engaging protrusion 51 fits into the engaging groove 52, the engaging surface 51b of the engaging protrusion 51 engages with the engaged surface 52a of the engaging groove 52.

[0047] By this engagement, the first limiting portion 5 limits the relative movement of the tube 72 to one axial side with respect to the first inner circumferential surface portion 211 of the outer joint pipe 2. As a result, the first limiting portion 5 can prevent the tube 72 from slipping out to one axial side with respect to the first inner circumferential surface portion 211 of the outer joint pipe 2.

[0048] 12 , the worker inserts the inner joint pipe 3 relatively from the other axial side of the outer joint pipe 2 into the inner peripheral side of the outer joint pipe 2. At that time, the worker inserts the inner joint pipe 3 from one axial end of the inner joint pipe 3 into the inner peripheral side of the outer joint pipe 2. As a result, the first outer peripheral surface portion 341, the tapered surface 343, and the second outer peripheral surface portion 342 of the inner joint pipe 3 are inserted relatively in this order into the inner peripheral side of the outer joint pipe 2.

[0049] The inner joint pipe 3, which has been inserted relatively into the inner peripheral side of the outer joint pipe 2, is further inserted relatively into the inner peripheral side of the end of the tube 72 fitted into the first inner peripheral surface portion 211 of the outer joint pipe 2. As a result, the inner joint pipe 3 moves relatively to the other axial side while part of its first outer peripheral surface portion 341 fits into the inner peripheral surface 72a of the end of the tube 72. During this movement, the seal member 4 on the inner joint pipe 3 side comes into close contact with the inner peripheral surface 72a of the end of the tube 72 (see FIG. 13 ). As a result, the gap between the first outer peripheral surface portion 341 of the inner joint pipe 3 and the inner peripheral surface 72a of the end of the tube 72 is sealed by the seal member 4.

[0050] When the inner joint pipe 3 moves further toward the other axial side within the tube 72, the hook portion 61 on the outer joint pipe 2 side comes into contact with the tapered surface 343 of the inner joint pipe 3, as shown by the solid line in Fig. 13 . When the worker presses the inner joint pipe 3 toward one axial side relative to the outer joint pipe 2 from this state, the hook portion 61 abutting against the tapered surface 343 presses the tip end 24b of the flexible piece 24 of the outer joint pipe 2 radially outward. This pressing force causes the tip end 24b of the flexible piece 24 to bend and deform radially outward, so the hook portion 61 moves relatively from one axial side to the other axial side along the tapered surface 343 while being displaced radially outward. As a result, the second plate portion 61b of the hook portion 61 rides up on the second outer circumferential surface portion 342 of the inner joint pipe 3, as shown by the two-dot chain line in Fig. 13 .

[0051] From this state, when the worker further pushes the inner joint pipe 3 relatively toward one side in the axial direction, the hook portion 61 fits into the hook groove 62 of the second restricting portion 6, as shown in Figure 14. As a result, the entire second outer peripheral surface portion 342 of the inner joint pipe 3 is fitted into the second inner peripheral surface portion 212 of the outer joint pipe 2, and the entire first outer peripheral surface portion 341 of the inner joint pipe 3 is fitted into the inner peripheral surface 72a of the end of the tube 72.

[0052] As described above, by fitting the hook portion 61 into the hook groove 62, the second limiting portion 6 limits the relative movement of the inner joint pipe 3 toward the other axial side with respect to the second inner circumferential surface portion 212 of the outer joint pipe 2. This makes it possible for the second limiting portion 6 to prevent the inner joint pipe 3 from slipping out toward the other axial side with respect to the second inner circumferential surface portion 212 of the outer joint pipe 2.

[0053] <Operation and Effect> According to the pipe joint structure 1 of the first embodiment, by relatively inserting the tube 72 into the inner peripheral side of the outer joint pipe 2 from one axial side, the outer peripheral surface 72b of the tube 72 is fitted into the first inner circumferential surface portion 211 of the outer joint pipe 2. As a result, the relative movement of the tube 72 toward one axial side with respect to the first inner circumferential surface portion 211 of the outer joint pipe 2 can be restricted by the first restricting portion 5. In this state, by relatively inserting the inner joint pipe 3 into the inner peripheral side of the outer joint pipe 2 from the other axial side, the first outer peripheral surface portion 341 of the inner joint pipe 3 is fitted into the inner circumferential surface 72a of the tube 72, and the second outer peripheral surface portion 342 of the inner joint pipe 3 is fitted into the second inner circumferential surface portion 212 of the outer joint pipe 2. As a result, the gap between the first outer peripheral surface portion 341 of the inner joint pipe 3 and the inner peripheral surface 72a of the tube 72 is sealed by the seal member 4, and the relative movement of the inner joint pipe 3 toward the other axial side with respect to the second inner peripheral surface portion 212 of the outer joint pipe 2 can be restricted by the second restricting portion 6. Therefore, an operator can easily connect the tube 72 to the pipe joint structure 1 without using tools by simply inserting the tube 72 relatively to the inner peripheral side of the outer joint pipe 2 from one axial side, and then inserting the inner joint pipe 3 relatively to the inner peripheral side of the outer joint pipe 2 from the other axial side.

[0054] The first restricting portion 5 is configured so that the engaging projection 51 on the outer joint pipe 2 side engages with the engaging groove 52 on the tube 72 side, so that the relative movement of the tube 72 with respect to the outer joint pipe 2 can be reliably restricted.

[0055] The engagement groove 52 of the first restricting portion 5 is located on the other axial side of the seal member 4 that seals between the tube 72 and the outer joint pipe 2. Therefore, the seal member 4 can prevent the transport fluid in the tube 72 from leaking from the engagement groove 52 to one axial side of the outer joint pipe 2. This eliminates the need to provide a separate seal structure between the tube 72 and the outer joint pipe 2, thereby simplifying the configuration of the pipe joint structure 1.

[0056] The second limiting portion 6 is configured so that the hook portion 61 on the outer joint pipe 2 side is hooked into the hook groove 62 on the inner joint pipe 3 side, thereby reliably restricting the relative movement of the inner joint pipe 3 with respect to the outer joint pipe 2. Furthermore, since the hook portion 61 is provided integrally with the outer joint pipe 2, the configuration of the pipe joint structure 1 can be simplified.

[0057] Since the outer joint pipe 2 does not come into contact with the corrosive fluid that is the transport fluid, the outer joint pipe 2 can be made of a cheaper material than a corrosion-resistant material, thereby reducing the manufacturing cost of the pipe joint structure 1.

[0058] [Second embodiment] <Configuration of pipe joint structure> Fig. 15 is a perspective view showing a pipe joint structure 1 according to a second embodiment. Fig. 16 is a view of the outer joint pipe 2 of the pipe joint structure 1 as viewed from the other axial side. In this embodiment, the configurations of the outer joint pipe 2 and the second limiting portion 6 differ from those of the first embodiment. In Figs. 15 and 16, the outer joint pipe 2 of this embodiment is a cylindrical member without a slit. A pair of through holes 25 is formed at the other axial end of the outer joint pipe 2.

[0059] The pair of through holes 25 are formed at equal intervals (180° intervals) in the circumferential direction of the outer joint pipe 2. Each through hole 25 is an elongated hole that is long in the circumferential direction and is formed by penetrating the outer joint pipe 2 in the thickness direction. The radial inner end of each through hole 25 opens at the second inner circumferential surface portion 212 of the outer joint pipe 2.

[0060] The second limiting portion 6 has a locking rod 63, a pair of guides 64, a pair of first stoppers 65, and a pair of second stoppers 66. The locking rod 63 is provided on the outer joint pipe 2 as a separate member from the outer joint pipe 2. The locking rod 63 is a rod-shaped part made of, for example, the same synthetic resin material as the outer joint pipe 2. The locking rod 63 in this embodiment is formed, for example, curved in a substantially U-shape. The locking rod 63 has a pair of locking portions 631, an operating portion 632, and a pair of guided portions 633.

[0061] The pair of locking portions 631 extend in the tangential direction and are arranged parallel to each other on both radial sides of the outer joint pipe 2. In this embodiment, the up-and-down direction in Fig. 16 is the tangential direction of the outer joint pipe 2 in which the locking portions 631 extend. A longitudinal portion 631a of each locking portion 631 is inserted along the longitudinal direction of each through hole 25 of the outer joint pipe 2, and protrudes (exposed) radially inward beyond the second inner circumferential surface portion 212 of the outer joint pipe 2.

[0062] Hereinafter, in this disclosure, the up-down direction in Fig. 16 will be simply referred to as the "tangential direction." For convenience, the upper side of Fig. 16 will be referred to as the "tangential upper side," and the lower side of Fig. 16 will be referred to as the "tangential lower side." Furthermore, the left-right direction in Fig. 16 is a direction perpendicular to the "tangential direction," and will be simply referred to as the "orthogonal direction." For convenience, the direction from the center point (axis O) of the outer joint pipe 2 to both sides in the orthogonal direction will be referred to as the "orthogonal outward direction," and the direction from both sides in the orthogonal direction of the outer joint pipe 2 toward the center point of the outer joint pipe 2 will be referred to as the "orthogonal inward direction" (the same applies to Fig. 23).

[0063] The operating portion 632 of the locking rod 63 connects the upper tangential ends of the pair of locking portions 631. The operating portion 632 is a portion that is operated by the operator's fingers. The operating portion 632 is disposed above and away from the outer peripheral surface 22 of the outer joint pipe 2 in the tangential direction. The pair of guided portions 633 of the locking rod 63 bend from the lower tangential end of each locking portion 631 and extend to one side in the axial direction. Each guided portion 633 is disposed outward in the perpendicular direction from the outer peripheral surface 22 of the outer joint pipe 2.

[0064] The pair of guides 64 guides each guided portion 633 of the locking rod 63. Each guide 64 is fixed adjacent to and below each through hole 25 in the tangential direction on the outer peripheral surface 22 of the outer joint pipe 2. Each guide 64 in this embodiment is provided integrally with the outer peripheral surface 22 of the outer joint pipe 2, and protrudes outward in the perpendicular direction from the outer peripheral surface 22. Each guide 64 has a guide surface 64a formed on its upper side in the tangential direction.

[0065] The guide surface 64a is a concave curved surface that slopes from the inner side in the orthogonal direction and the upper side in the tangential direction to the outer side in the orthogonal direction and the lower side in the tangential direction. The guided portion 633 of the locking rod 63 abuts against the guide surface 64a of each guide 64. The guided portion 633 slides along the guide surface 64a.

[0066] A pair of first stoppers 65 are fixed adjacent to and above each guide 64 in the tangential direction on the outer peripheral surface 22 of the outer joint pipe 2. In this embodiment, each first stopper 65 is provided integrally with the outer peripheral surface 22 of the outer joint pipe 2. Each first stopper 65 has a stopper surface 65a formed on its lower side in the tangential direction. The guided portion 633 of the locking rod 63 abuts against the stopper surface 65a. In the state shown in Figures 15 and 16, each guided portion 633 of the locking rod 63 is located above the guide surface 64a of each guide 64 in the tangential direction and abuts against the stopper surface 65a of each first stopper 65.

[0067] A pair of second stoppers 66 are fixed to the outer sides of each guide 64 in the orthogonal direction. In this embodiment, each second stopper 66 is integrally formed with the guide 64. Each second stopper 66 protrudes upward in the tangential direction and outward in the orthogonal direction relative to the guide surface 64a. Each second stopper 66 has a stopper surface 66a formed on the guide surface 64a side. When the guided portion 633 of the locking rod 63 slides downward in the tangential direction along the guide surface 64a, it abuts against the stopper surface 66a of the second stopper 66.

[0068] 17 is a diagram showing a state in which the guided portions 633 of the locking rod 63 have slid tangentially downward along the guide surfaces 64a of the guides 64 from the state shown in FIG. 16 . As shown in FIG. 17 , when the pair of guided portions 633 slide tangentially downward along the guide surfaces 64a of the guides 64, the pair of locking portions 631 move away from each other outward in the perpendicular direction. As a result, each locking portion 631 moves from a protruding position ( FIG. 16 ) in which a portion 631a protrudes radially inward from the second inner circumferential surface portion 212 of the outer joint pipe 2 to a retracted position ( FIG. 17 ) in which the portion 631a retracts radially outward from the second inner circumferential surface portion 212. Therefore, each locking portion 631 is provided with respect to the outer joint pipe 2 so as to be able to protrude radially inward from the second inner circumferential surface portion 212 and to be able to retract radially outward from the second inner circumferential surface portion 212.

[0069] Figure 18 is a perspective view showing the inner joint pipe 3 of the second embodiment. In Figures 15, 16, and 18, the second limiting portion 6 further has a pair of locking grooves 67 (only one is shown in Figure 18) provided in the inner joint pipe 3. The pair of locking grooves 67 are provided in the second outer peripheral surface portion 342 of the inner joint pipe 3. Specifically, the pair of locking grooves 67 are formed at equal intervals (180° intervals) in the circumferential direction on the second outer peripheral surface portion 342 of the inner joint pipe 3. Each locking groove 67 is, for example, a recessed groove that is elongated in the circumferential direction. A portion 631a of each locking portion 631 of the locking rod 63 fits into each engagement groove 52 along its longitudinal direction and is locked. Therefore, each locking groove 67 is formed to a size that allows the portion 631a of the locking portion 631 to fit into it.

[0070] With the second outer peripheral surface portion 342 of the inner joint pipe 3 fitted to the second inner peripheral surface portion 212 of the outer joint pipe 2, the pair of locking portions 631 of the second limiting portion 6 are locked in the locking grooves 67 at the protruding positions (see FIG. 21 ). Therefore, the second limiting portion 6 limits the relative movement of the inner joint pipe 3 toward the other axial side with respect to the second inner peripheral surface portion 212 of the outer joint pipe 2.

[0071] With the relative movement of the inner joint pipe 3 restricted by the second restricting portion 6, the locking rod 63 is in the position shown in Fig. 16. From this state, when the operator pushes the operating portion 632 of the locking rod 63 downward in the tangential direction, the pair of guided portions 633 slide downward in the tangential direction along the guide surfaces 64a of the respective guides 64, as shown in Fig. 17. This sliding causes the pair of locking portions 631 to move away from each other outward in the perpendicular direction.

[0072] As a result, each locking portion 631 moves from the protruding position (FIG. 16) to the retracted position (FIG. 17), and the pair of locking portions 631 are released from locking with each locking groove 67. From this state, the worker can move the outer joint pipe 2 relatively to the inner joint pipe 3 toward the other axial side, thereby relatively separating the outer joint pipe 2 from the inner joint pipe 3. Since other configurations of this embodiment are similar to those of the first embodiment, the same reference numerals are used and their description will be omitted.

[0073] <Construction Method of Pipe Joint Structure> Next, a construction method for connecting the tube 72 to the pipe joint structure 1 of this embodiment will be described. Figures 19 to 21 are explanatory views of the construction method. First, as in the first embodiment (see Figures 9 to 11), the worker inserts the end of the tube 72 relatively from one axial side of the outer joint pipe 2 into the inner periphery of the outer joint pipe 2, and fits the outer periphery 72b of the end of the tube 72 into the first inner periphery portion 211 of the outer joint pipe 2. At this time, the locking rod 63 of the second limiting portion 6 is maintained in the state shown in Figure 16.

[0074] Next, as shown in Figure 19, the worker inserts the inner joint pipe 3 relatively from the other axial side of the outer joint pipe 2 into the inner peripheral side of the outer joint pipe 2. Since the insertion operation is the same as in the first embodiment, detailed description will be omitted. When the inner joint pipe 3 is relatively inserted into the inner peripheral side of the outer joint pipe 2, the locking portion 631 (part 631a) of the locking rod 63 comes into contact with the tapered surface 343 of the inner joint pipe 3, as shown by the solid line in Figure 20.

[0075] From this state, when the worker presses the inner joint pipe 3 relatively toward one axial side with respect to the outer joint pipe 2, the locking portions 631 move relatively from one axial side to the other axial side along the tapered surface 343, and move from the inner side in the orthogonal direction to the outer side in the orthogonal direction. As a result, as shown by the two-dot chain line in Figure 20, the locking portions 631 move from the protruding position (Figure 16) to the retracted position (Figure 17), and ride on the second outer peripheral surface portion 342 of the inner joint pipe 3. At that time, each guided portion 633 of the locking rod 63 slides along the guide surfaces 64a of each guide 64, so that each locking portion 631 can be moved smoothly.

[0076] From this state, when the worker further pushes the inner joint pipe 3 relatively toward one side in the axial direction, the locking portion 631 fits into and is locked in the locking groove 67 of the second limiting portion 6, as shown in Figure 21. As a result, the entire second outer peripheral surface portion 342 of the inner joint pipe 3 is fitted into the second inner peripheral surface portion 212 of the outer joint pipe 2, and the entire first outer peripheral surface portion 341 of the inner joint pipe 3 is fitted into the inner peripheral surface 72a of the end of the tube 72.

[0077] As a result of the locking portion 631 being locked in the locking groove 67, as described above, the second limiting portion 6 limits the relative movement of the inner joint pipe 3 toward the other axial side with respect to the second inner circumferential surface portion 212 of the outer joint pipe 2. This makes it possible for the second limiting portion 6 to prevent the inner joint pipe 3 from slipping out toward the other axial side with respect to the second inner circumferential surface portion 212 of the outer joint pipe 2.

[0078] <Operation and Effect> In the pipe joint structure 1 of the second embodiment, too, an operator can easily connect the tube 72 to the pipe joint structure 1 without using any tools by simply inserting the tube 72 relatively from one axial side into the inner peripheral side of the outer joint pipe 2, and then inserting the inner joint pipe 3 relatively from the other axial side into the inner peripheral side of the outer joint pipe 2. Furthermore, since the second limiting part 6 is configured so that the locking part 631 on the outer joint pipe 2 side is locked into the locking groove 67 on the inner joint pipe 3 side, it is possible to reliably limit the relative movement of the inner joint pipe 3 with respect to the outer joint pipe 2.

[0079] [Third Embodiment] <Configuration of Pipe Joint Structure> Figure 22 is a perspective view showing a pipe joint structure 1 according to a third embodiment. Figure 23 is a view of the outer joint pipe 2 of the pipe joint structure 1 as viewed from the other axial side. Figure 24 is a view of the outer joint pipe 2 as viewed from below in Figure 23. Note that the inner joint pipe 3 in Figure 22 is shown on one axial side of the annular portion 31 (see Figure 6) (the same applies to Figure 27). This embodiment is a modification of the second embodiment, and differs from the second embodiment in the configuration of the second limiting portion 6. In Figures 22 to 24, the second limiting portion 6 of this embodiment has a locking rod 83.

[0080] Figure 25 is a perspective view showing the locking rod 83. In Figures 22 to 25, the locking rod 83 is provided on the outer joint pipe 2 as a separate member from the outer joint pipe 2. The locking rod 83 is a rod-shaped part made of, for example, the same synthetic resin material as the outer joint pipe 2. The locking rod 83 of this embodiment has a pair of locking portions 831, a pair of guided portions 832, a pair of operating portions 833, a pair of first stopper portions 834, and a second stopper portion 835.

[0081] The pair of locking portions 831 extend in the tangential direction on both sides of the outer joint pipe 2 in the orthogonal direction, and are arranged parallel to each other with a predetermined gap between them. In this embodiment, the up-and-down direction in Fig. 23 is the tangential direction of the outer joint pipe 2 in which the locking portions 831 extend. A longitudinal portion 831a of each locking portion 831 is inserted along the longitudinal direction of each through hole 25 of the outer joint pipe 2, and protrudes (exposed) radially inward beyond the second inner circumferential surface portion 212 of the outer joint pipe 2.

[0082] The pair of guided portions 832 extend obliquely inward in the orthogonal direction and upward in the tangential direction from the upper end of each locking portion 831 in the tangential direction. Most of each guided portion 832 is arranged above the outer peripheral surface 22 of the outer joint pipe 2 in the tangential direction. The pair of operating portions 833 extend from the upper end of each guided portion 832 in the tangential direction to one side in the axial direction, and are arranged close to each other and parallel to each other. In this embodiment, the pair of operating portions 833 are close to each other enough that an operator can simultaneously push them downward in the tangential direction with a single finger.

[0083] The pair of first stopper portions 834 bend from the tangentially lower end of each locking portion 831 and extend to one axial side. The second stopper portion 835 connects the axially opposite ends of the pair of operating portions 833. The second stopper portion 835 has a pair of extending portions 835a and a connecting portion 835b. Each extending portion 835a extends obliquely from the axially opposite end of the corresponding operating portion 833 toward one axial side and the tangentially downward direction. The connecting portion 835b extends perpendicularly between the tangentially lower ends of the pair of extending portions 835a and connects these ends together.

[0084] 22 to 24 , the second limiting portion 6 further has a pair of guide grooves 84, a pair of first stopper grooves 85, and a second stopper groove 86 formed in the outer joint pipe 2. The pair of guide grooves 84 are formed tangentially above each through hole 25 of the outer joint pipe 2. Each guide groove 84 communicates with the corresponding through hole 25 and extends tangentially upward from that through hole 25. Each guide groove 84 is a bottomed groove that opens in the outer circumferential surface 22 of the outer joint pipe 2.

[0085] A guide surface 84a is formed on the bottom surface of each guide groove 84, sloping from the inner side in the orthogonal direction and upper side in the tangential direction to the outer side in the orthogonal direction and lower side in the tangential direction. The upper end of the guide surface 84a in the tangential direction is connected to the outer peripheral surface 22 of the outer joint pipe 2. The lower end of the tangential direction of each guided portion 832 of the locking rod 83 abuts against the guide surface 84a of each guide groove 84. The end of each guided portion 832 slides obliquely along the corresponding guide surface 64a.

[0086] A pair of first stopper grooves 85 are formed below the tangential direction of each through hole 25 of the outer joint pipe 2. Each first stopper groove 85 communicates with the corresponding through hole 25, and extends from the below the tangential direction of the through hole 25 to one axial direction side. Each first stopper groove 85 is a bottomed groove that opens in the outer peripheral surface 22 of the outer joint pipe 2. A bottom surface 85a of each first stopper groove 85 extends in the tangential direction from the lower end of the through hole 25 in the tangential direction to the outer peripheral surface 22 of the outer joint pipe 2.

[0087] A stopper surface 85b is formed on the tangentially upper side of each first stopper groove 85. The stopper surface 85b extends in the perpendicular direction from the tangentially lower end of the through hole 25 to the outer peripheral surface 22 of the outer joint pipe 2. In the state shown in Figures 22 and 23, each first stopper portion 834 of the locking rod 83 abuts against the bottom surface 85a and stopper surface 85b of each first stopper groove 85. This limits the upward movement of the locking rod 83 in the tangential direction.

[0088] The second stopper groove 86 is formed on one axial side of the outer peripheral surface 22 of the outer joint pipe 2. The second stopper groove 86 is formed at an intermediate position between the pair of guide grooves 84 and tangentially below the connecting portion 835b of the second stopper portion 835 of the locking rod 83. The second stopper groove 86 is a bottomed groove that opens at the outer peripheral surface 22 of the outer joint pipe 2. The bottom surface of the second stopper groove 86 is formed as a stopper surface 86b. The stopper surfaces 86b extend on both sides in the perpendicular direction until they reach the outer peripheral surface 22 of the outer joint pipe 2. When the second stopper portion 835 of the locking rod 83 moves downward in the tangential direction, the connecting portion 835b of the second stopper portion 835 abuts against the stopper surface 86b of the second stopper groove 86.

[0089] Figure 26 is a diagram showing a state in which the locking rod 83 has moved downward in the tangential direction from the state shown in Figure 23. As shown in Figure 26, when the locking rod 83 moves downward in the tangential direction, the lower ends of the pair of guided portions 832 slide obliquely outward in the perpendicular direction and downward in the tangential direction along the inclined guide surfaces 84a of each guide groove 84. As a result, the pair of locking portions 831 move away from each other outward in the perpendicular direction.

[0090] As a result, each locking portion 831 moves from a protruding position ( FIG. 23 ) where a part 831 a protrudes radially inward from the second inner circumferential surface portion 212 of the outer joint pipe 2, to a retracted position ( FIG. 26 ) where the part 831 a is retracted radially outward from the second inner circumferential surface portion 212. Therefore, each locking portion 831 is provided so as to be able to protrude radially inward from the second inner circumferential surface portion 212 with respect to the outer joint pipe 2, and to be able to retract radially outward from the second inner circumferential surface portion 212. When each locking portion 831 moves from the protruding position to the retracted position, the second stopper portion 835 (connecting portion 835 b) of the locking rod 83 comes into contact with the second stopper groove 86 (stopper surface 86 b) of the outer joint pipe 2, thereby restricting the downward movement of the locking rod 83 in the tangential direction.

[0091] Figure 27 is a cross-sectional perspective view showing the inner joint pipe 3 of the third embodiment. In Figures 22, 23, and 27, the second limiting portion 6 further has a locking groove 87 provided in the inner joint pipe 3. The locking groove 87 is provided in the second outer peripheral surface portion 342 of the inner joint pipe 3. The locking groove 87 of this embodiment is formed in an annular shape over the entire circumferential direction of the second outer peripheral surface portion 342. Although not shown, parts 831a of the locking portions 831 of the locking rod 83 fit into and are locked into the locking groove 87. For this reason, the locking groove 87 is formed to a size that allows the parts 831a of the locking portions 831 to fit into it. As in the second embodiment, a pair of locking grooves 87 may be formed at equal intervals in the circumferential direction of the inner joint pipe 3.

[0092] With the second outer peripheral surface portion 342 of the inner joint pipe 3 fitted into the second inner peripheral surface portion 212 of the outer joint pipe 2, the pair of locking portions 831 of the locking rod 83 are locked in the respective locking grooves 67 of the inner joint pipe 3 at the protruding position. Therefore, the second limiting portion 6 (locking rod 83 and locking grooves 87) limits the relative movement of the inner joint pipe 3 toward the other axial side with respect to the second inner peripheral surface portion 212 of the outer joint pipe 2.

[0093] With the relative movement of the inner joint pipe 3 restricted by the second restricting portion 6, the locking rod 83 is in the position shown in Fig. 23 . To release the restriction on the movement of the inner joint pipe 3 from this state, the operator simultaneously pushes the pair of operating portions 833 of the locking rod 83 downward in the tangential direction with a single finger (for example, the thumb). As a result, as shown in Fig. 26 , the lower ends of the pair of guided portions 832 in the tangential direction slide obliquely outward in the perpendicular direction and downward in the tangential direction along the guide surfaces 84a of the respective guide grooves 84. This sliding causes the pair of locking portions 831 to move away from each other outward in the perpendicular direction.

[0094] As a result, each locking portion 831 moves from the protruding position (FIG. 23) to the retracted position (FIG. 26), so that the pair of locking portions 831 are released from locking with each locking groove 87, and the restriction on movement of the inner joint pipe 3 by the second restricting portion 6 is released. From this state, the worker can move the outer joint pipe 2 relatively to the inner joint pipe 3 toward the other axial side, thereby relatively separating the outer joint pipe 2 from the inner joint pipe 3.

[0095] Other configurations of this embodiment are the same as those of the second embodiment, and therefore the same reference numerals are used and a description thereof will be omitted. Furthermore, if the locking rod 63, locking portion 631, guided portion 633, guide 64, and locking groove 67 of the second embodiment are respectively replaced with the locking rod 83, locking portion 831, guided portion 832, guide groove 84, and locking groove 87 of the third embodiment, the construction method of the pipe joint structure 1 in the third embodiment is the same as that of the second embodiment, and therefore a description thereof will be omitted.

[0096] <Operation and Effect> In the pipe joint structure 1 of the third embodiment, too, an operator can easily connect the tube 72 to the pipe joint structure 1 without using any tools by simply inserting the tube 72 relatively from one axial side into the inner peripheral side of the outer joint pipe 2, and then inserting the inner joint pipe 3 relatively from the other axial side into the inner peripheral side of the outer joint pipe 2. Furthermore, since the second limiting portion 6 is configured so that the locking portion 831 on the outer joint pipe 2 side is locked into the locking groove 87 on the inner joint pipe 3 side, it is possible to reliably limit the relative movement of the inner joint pipe 3 with respect to the outer joint pipe 2.

[0097] The locking rod 83 has a pair of operating parts 833 arranged parallel to and close to each other. This allows the operator to simultaneously press the pair of operating parts 833 with a single finger when releasing the restriction on movement of the inner joint pipe 3 imposed by the second restricting part 6. As a result, the strain on the operator's fingers can be reduced compared to when a single operating part 632 is pressed as in the second embodiment (see FIG. 15 ).

[0098] A pair of guide grooves 84 corresponding to the pair of guides 64 of the second embodiment (see FIG. 16 ) are formed in the outer joint pipe 2. This makes it possible to manufacture the outer joint pipe 2 more easily than when a pair of guides 64 is provided on the outer peripheral surface 22 of the outer joint pipe 2. Also, the pipe joint structure 1 can be configured compactly in the orthogonal direction.

[0099] [Others] The above-disclosed embodiments are illustrative in all respects and are not limiting. For example, the pipe joint structure 1 of the present disclosure can be applied to semiconductor manufacturing equipment, the liquid crystal / organic electroluminescence (LCD) field, the medical / pharmaceutical field, or the automotive field, in addition to hydrogen carrier manufacturing equipment. Furthermore, the sealing member 4 may be a packing other than an O-ring.

[0100] The first limiting portion 5 is not limited to the above embodiment. For example, the engagement groove 52 may be a recessed groove that does not penetrate the tube 72 in the thickness direction. The engagement groove 52 may also be located on one axial side of the seal member 4. In this case, a separate seal structure may be provided between the tube 72 and the outer joint pipe 2 on one axial side of the engagement groove 52.

[0101] The first restricting portion 5 may have one or three or more engaging protrusions 51 and engaging grooves 52 provided in the circumferential direction. The engaging protrusions 51 may be separate from the outer joint pipe 2. The engaging protrusions 51 may be provided on the outer peripheral surface 72b of the end of the tube 72, and the engaging grooves 52 may be provided on the first inner peripheral surface portion 211 of the outer joint pipe 2.

[0102] For example, as shown in Fig. 28 , an annular engaging protrusion 51 may be integrally formed at the end of the tube 72 by projecting a portion of the axial direction outward in the radial direction, and an annular engaging groove 52 with which the engaging protrusion 51 engages may be formed on the first inner circumferential surface portion 211 of the outer joint pipe 2. Note that although the engaging groove 52 in Fig. 28 is formed so as to be located on the other axial side of the seal member 4, it may also be formed so as to be located on one axial side of the seal member 4 as shown in Fig. 29 . The first limiting portion 5 shown in Figs. 28 and 29 is effective when it is difficult to machine the engaging groove 52 in the tube 72 as in the first embodiment (see Fig. 7 ).

[0103] The second restricting portion 6 is not limited to the above embodiment. For example, one or three or more hook portions 61 and hook grooves 62 may be provided in the circumferential direction. The hook portion 61 may be separate from the outer joint pipe 2. The hook portion 61 may be provided on the second outer peripheral surface portion 342 of the inner joint pipe 3, and the hook groove 62 may be provided on the second inner peripheral surface portion 212 of the outer joint pipe 2.

[0104] REFERENCE SIGNS LIST 1 Pipe joint structure 2 Outer joint pipe 3 Inner joint pipe 4 Sealing member 5 First limiting portion 6 Second limiting portion 51 Engaging protrusion 52 Engaging groove 61 Hooking portion 62 Hooking groove 67 Locking groove 70 Fluid equipment (fluid device) 71 Flow path 72 Tube (piping) 72a Inner peripheral surface 72b Outer peripheral surface 87 Locking groove 211 First inner peripheral surface portion 212 Second inner peripheral surface portion 341 First outer peripheral surface portion 342 Second outer peripheral surface portion 631 Locking portion 831 Locking portion

Claims

1. A pipe joint structure for connecting a pipe to a flow path formed in a fluid device, comprising: an outer joint pipe having a first inner circumferential surface portion on one axial side and a second inner circumferential surface portion on the other axial side, with an outer circumferential surface of the pipe being fitted to the first inner circumferential surface portion from the one axial side; an inner joint pipe having a first outer circumferential surface portion on the one axial side that is fitted to the inner circumferential surface of the pipe from the other axial side and a second outer circumferential surface portion on the other axial side that is fitted to the second inner circumferential surface portion of the outer joint pipe from the other axial side, with an end on the other axial side being connected to the fluid device; an annular seal member provided on the first outer circumferential surface portion of the inner joint pipe, sealing between the first outer circumferential surface portion and the inner surface of the pipe; and a first restriction portion, the outer circumferential surface of the pipe being fitted to the first inner circumferential surface portion of the outer joint pipe, thereby restricting relative movement of the pipe to the one axial side with respect to the first inner circumferential surface portion. a second limiting portion that limits relative movement of the inner joint pipe toward the other axial side with respect to the second inner circumferential surface portion by fitting the second outer circumferential surface portion of the inner joint pipe into the second inner circumferential surface portion of the outer joint pipe.

2. The pipe joint structure described in claim 1, wherein the first restriction portion has an engagement protrusion provided on one of the first inner surface portion of the outer joint pipe and the outer surface of the piping, and an engagement groove provided on the other, and the relative movement of the piping is restricted by the engagement of the engagement protrusion with the engagement groove.

3. A pipe joint structure as set forth in claim 2, wherein the engagement groove is located on the other axial side of the seal member.

4. A pipe joint structure as claimed in any one of claims 1 to 3, wherein the second restriction portion has a hook portion integrally formed on one of the second inner peripheral surface portion of the outer joint pipe and the second outer peripheral surface portion of the inner joint pipe, and a hook groove formed on the other, and the relative movement of the inner joint pipe is restricted by the hook portion being hooked into the hook groove.

5. A pipe joint structure as claimed in any one of claims 1 to 3, wherein the second limiting portion has an engaging portion which is provided on the outer joint pipe as a separate body from the outer joint pipe and which is capable of protruding radially inward beyond the second inner peripheral surface portion, and an engaging groove which is provided on the second outer peripheral surface portion of the inner joint pipe, and wherein the relative movement of the inner joint pipe is restricted by the engaging portion protruding radially inward and engaging with the engaging groove.

6. A construction method for connecting a pipe to a pipe fitting structure described in any one of claims 1 to 3 for connecting the pipe to a flow path formed in a fluid device, comprising the steps of: inserting the pipe relatively from one axial side of the outer fitting pipe into the inner periphery of the outer fitting pipe and fitting the outer periphery of the pipe into the first inner periphery of the outer fitting pipe; and inserting the inner fitting pipe relatively from the other axial side of the outer fitting pipe into the inner periphery of the outer fitting pipe and fitting the first outer periphery of the inner fitting pipe into the second inner periphery of the outer fitting pipe, in this order.

Images