Pipe fittings

Abstract

A pipe joint that can improve reliability is provided. [Solution] The fitting comprises a cylindrical fitting body (21) for connecting a resin pipe (P), a nut member (22) threaded onto the fitting body (21), and a plurality of anti-slip rings (23) arranged between the fitting body (21) and the nut member (22), the anti-slip ring (23) having an annular base portion (81) and a plurality of bent pieces (92) arranged circumferentially around the base portion (81) with slits between them and extending radially inward from the inner side of the base portion (81) at an angle to the axial direction of the fitting body (21), and an outer diameter (D1) larger than the inner diameter (D2) of the fitting body (21).

Description

[Technical Field]

[0001] The present invention relates to a pipe joint. [Background technology]

[0002] Conventionally, in external watertight joints that house a seal member on the inner peripheral surface of the joint body and seal the water by bringing the seal member into contact with the outer surface of a pipe inserted inside the joint body, there is known a joint structure that has a single retaining ring that prevents the pipe from coming out (see, for example, Patent Document 1). Because this pipe joint has only one retaining ring, the ultimate pull-out strength of the pipe is low. When excessive pull-out force is generated at the construction site, a pipe joint structured with a single retaining ring may experience pipe slip-out.

[0003] For this reason, there are pipe joints that have two retaining rings that prevent the pipe from coming off (see, for example, Patent Document 2). With such a pipe joint, the presence of two retaining rings increases the ultimate pull-out strength of the pipe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-168980 [Patent Document 2] Japanese Patent Publication No. 2024-045855 Summary of the Invention [Problem to be solved by the invention]

[0005] In the pipe fitting described in Patent Document 2, the retaining ring is positioned radially inward of the fitting body, so the distance between the radially outer end of the retaining ring's slit and the radially outermost end of the retaining ring is short. It is believed that such a pipe fitting has sufficient pipe pull-out fatigue strength for normal use in residential apartments, detached houses, etc. However, when used in an environment where pull-out fatigue constantly occurs (for example, an environment where water hammer occurs), the retaining ring may be damaged, resulting in water leakage.

[0006] In view of the above circumstances, an object of the present invention is to provide a pipe joint that can improve reliability. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following aspects. <1> A pipe fitting according to one aspect of the present invention comprises: a cylindrical joint body for connecting resin pipes; a nut member that is threadedly attached to the joint body; a plurality of retaining rings disposed between the joint body and the nut member, The retaining ring is a circular substrate portion; a plurality of bent pieces arranged in the circumferential direction of the base plate portion with slits between them, the bent pieces extending radially inward from the inner circumferential side of the base plate portion at an angle with respect to the axial direction of the joint body, The outer diameter is larger than the inner diameter of the fitting body.

[0008] <1> The pipe joint has a plurality of retaining rings disposed between the joint body and the nut member, and therefore can improve the ultimate pull-out strength of the pipe. Furthermore, because the outer diameter of the retaining ring is larger than the inner diameter of the joint body, a sufficient distance can be secured between the radially outer end of the slit on the retaining ring and the radially outermost end of the retaining ring. Here, the cross-sectional area of ​​the non-slit portion of the base plate of the retaining ring affects the pull-out fatigue strength of the pipe joint. Specifically, the larger this cross-sectional area, the higher the pull-out fatigue strength of the retaining ring and the more likely it is that fatigue cracks will occur in the retaining ring. Therefore, assuming the thickness of the base plate is the same, the radial length of the non-slit portion of the base plate, in other words, the distance from the radially outermost end of the slit on the retaining ring to the radially outermost end of the retaining ring, affects the pull-out fatigue strength of the pipe joint. Specifically, if the distance from the radially outermost end of the slit on the retaining ring to the radially outermost end of the retaining ring becomes shorter, the pull-out fatigue strength of the retaining ring decreases and fatigue cracks will be more likely to occur in the retaining ring. In contrast, <1> In this pipe joint, the outer diameter of the retaining ring is larger than the inner diameter of the joint body, so the distance from the outermost radial end of the slit of the retaining ring to the outermost radial end of the retaining ring can be ensured, thereby improving the pull-out fatigue strength of the retaining ring and, ultimately, the pull-out fatigue strength of the pipe joint. Therefore, the reliability can be improved.

[0009] <2> The aforementioned <1> In the pipe fitting according to the present invention, it is preferable that the retaining ring includes a first retaining ring arranged on the insertion side of the pipe, and a second retaining ring arranged on the opposite side of the first retaining ring from the insertion side of the pipe. [Effects of the Invention]

[0010] As described above, the present invention has the effect of improving reliability. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing a pipe and a pipe fitting according to a first embodiment of the present invention. [Figure 2]1A and 1B show a retaining ring for a pipe joint according to a first embodiment of the present invention, where FIG. 1A is a plan view and FIG. 1B is a side cross-sectional view. [Figure 3] FIG. 4 is a cross-sectional view showing a pipe fitting and a pipe according to a second embodiment of the present invention. [Figure 4] FIG. 6 is a cross-sectional view showing a pipe fitting and a pipe according to a third embodiment of the present invention. [Figure 5] FIG. 10 is a cross-sectional view showing a pipe fitting and a pipe according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] [First embodiment] A pipe joint according to a first embodiment of the present invention will now be described with reference to FIGS.

[0013] As shown in Fig. 1, the pipe fitting 11 of the first embodiment is connected to a pipe P. The pipe fitting 11 constitutes various types of piping equipment (not shown), such as a water supply pipe, a drainage pipe (sewer pipe), a gas pipe, or an air conditioning pipe.

[0014] The pipe joint 11 has a cylindrical joint body 21 that connects to a pipe P, a nut member 22 that is threaded onto the joint body 21, a plurality of retaining rings 23 (specifically two) that are arranged between the joint body 21 and the nut member 22, a base member 24, a spacer 25, a seal member 26, and an incore 28. The joint body 21, nut member 22, the plurality of retaining rings 23, the base member 24, the spacer 25, and the seal member 26 form an outer constituent body 30, and the pipe joint 11 is made up of this outer constituent body 30 and an incore 28 that is separate from it.

[0015] The joint body 21, nut member 22, and incore 28 are formed in a cylindrical shape, while the plurality of retaining rings 23, base member 24, spacer 25, and seal member 26 are formed in an annular shape. The respective central axes of the joint body 21, nut member 22, plurality of retaining rings 23, base member 24, spacer 25, seal member 26, and incore 28 are arranged coaxially with a common axis. Hereinafter, this common axis will be referred to as axis O. The direction along axis O will be referred to as the axial direction. The direction perpendicular to axis O will be referred to as the radial direction, and the direction circumferential around axis O will be referred to as the circumferential direction.

[0016] Here, the pipe fitting 11 includes a fitting body 21, a nut member 22, a plurality of retaining rings 23, a base member 24, a spacer 25, a seal member 26, and an inner core 28, which constitute one fitting portion 31. Although not shown, the pipe fitting 11 also includes a second fitting portion having a similar configuration to the first fitting portion 31, which is axially mirror-symmetrical to the first fitting portion 31. The fitting body 21 has a mirror-symmetrical shape in the axial direction, and constitutes the first fitting portion 31 and the second fitting portion (not shown). The first fitting portion 31 is connected to one pipe P, and the second fitting portion (not shown) is connected to the second pipe (not shown). As a result, the pipe fitting 11 communicates the radially inner flow path of the first pipe P with the radially inner flow path of the second pipe (not shown). Here, the description will be given taking one joint portion 31 and one pipe P shown in FIG. 1 as an example.

[0017] At least the tip of the pipe P, which is connected to the pipe fitting 11, is cylindrical. The pipe P is made of resin, specifically, a polyolefin pipe for water supply. The pipe P is inserted into the fitting portion 31 from one axial side. In the following description, the near side in the insertion direction, which is the insertion side of the pipe P in the axial direction when the pipe P is inserted in the fitting portion 31, will be referred to as the near side in the pipe insertion direction, and the opposite side, i.e., the far side in the insertion direction, which is opposite to the insertion side of the pipe P in the axial direction when the pipe P is inserted, will be referred to as the far side in the pipe insertion direction.

[0018] The joint body 21 is formed in a hollow cylindrical shape extending in the axial direction, and is open at both axial ends. The inner peripheral surface of the joint body 21 has a multi-step shape. The joint body 21 has a cylindrical base portion 41 located in the axial center, i.e., at the rear side in the pipe insertion direction, and a cylindrical accommodation portion 42 located on the front side in the pipe insertion direction and constituting one of the joint portions 31. The base portion 41 of the joint body 21 has a shape that is mirror-symmetrical in the axial direction, and has an accommodation portion (not shown) on the opposite side of the accommodation portion 42 of the base portion 41 that is mirror-symmetrical to the accommodation portion 42. This accommodation portion (not shown) constitutes the other joint portion.

[0019] The pipe P is inserted into the radially inner side of the accommodation portion 42 from one axial side, i.e., the front side in the pipe insertion direction. A male thread 45 is formed on the outer periphery of the radially outer side of the accommodation portion 42. A flange portion 46 having a larger outer diameter than the male thread 45 is formed on the accommodation portion 42, further back in the pipe insertion direction than the male thread 45. The radially inner side of the accommodation portion 42 forms an accommodation recess 48 that is recessed along the axial direction from the front side in the pipe insertion direction to the back side in the pipe insertion direction. The accommodation recess 48 has, in order from the front side in the pipe insertion direction to the back side in the pipe insertion direction, a first inner circumferential surface 51, a first step surface 52, a second inner circumferential surface 53, a second step surface 54, a third inner circumferential surface 55, an engagement groove 56, and a third step surface 57.

[0020] The base portion 41 has, on its radially inner side, a fourth inner circumferential surface 58, a fourth step surface 59, and a fifth inner circumferential surface 60 in this order from the axial housing portion 42 side.

[0021] The first inner circumferential surface 51, the second inner circumferential surface 53, the third inner circumferential surface 55, the fourth inner circumferential surface 58, and the fifth inner circumferential surface 60 all face radially inward. The first step surface 52, the second step surface 54, the third step surface 57, and the fourth step surface 59 all face toward the front in the pipe insertion direction.

[0022] The first inner peripheral surface 51 has a cylindrical surface shape with the axis O as its center. The first step surface 52 has a flat surface extending radially inward so as to widen perpendicularly to the axis O from the rear side of the first inner circumferential surface 51 in the pipe insertion direction. The second inner peripheral surface 53 extends from the radially inner side of the first step surface 52 to the opposite side of the first inner peripheral surface 51 in the axial direction, and has a cylindrical surface shape with the axis O as its center. The first step surface 52 forms a step connecting the first inner circumferential surface 51 and the second inner circumferential surface 53 . The second step surface 54 has a flat surface extending radially inward so as to widen perpendicularly to the axis O from the side of the second inner peripheral surface 53 opposite to the first inner peripheral surface 51 in the axial direction. The third inner peripheral surface 55 extends from the radially inner side of the second step surface 54 to the opposite side of the second inner peripheral surface 53 in the axial direction, and has a cylindrical surface shape with the axis O as its center. The second step surface 54 forms a step connecting the second inner circumferential surface 53 and the third inner circumferential surface 55 . The engagement groove 56 is recessed radially outward from the end of the third inner circumferential surface 55 on the far side in the pipe insertion direction. The third step surface 57 forms the engagement groove 56 and has a flat surface extending radially inward so as to widen perpendicular to the axis O from the side of the engagement groove 56 opposite the third inner peripheral surface 55 in the axial direction.

[0023] The fourth inner peripheral surface 58 extends from the radially inner side of the third step surface 57 toward the opposite side of the third inner peripheral surface 55 in the axial direction, and has a cylindrical surface shape with the axis O as its center. The third step surface 57 forms a step that connects the engagement groove 56 and the fourth inner circumferential surface 58 . The fourth step surface 59 has a flat surface extending radially inward so as to widen perpendicularly to the axis O from the side of the fourth inner circumferential surface 58 opposite to the third inner circumferential surface 55 in the axial direction. The fifth inner peripheral surface 60 extends from the radially inner side of the fourth step surface 59 to the axially opposite side of the fourth inner peripheral surface 58, and has a cylindrical surface shape with the axis O as its center. The fourth step surface 59 forms a step connecting the fourth inner circumferential surface 58 and the fifth inner circumferential surface 60 .

[0024] The second inner circumferential surface 53 has a smaller diameter than the first inner circumferential surface 51, the third inner circumferential surface 55 has a smaller diameter than the second inner circumferential surface 53, the fourth inner circumferential surface 58 has a smaller diameter than the third inner circumferential surface 55, and the fifth inner circumferential surface 60 has a smaller diameter than the fourth inner circumferential surface 58. The fifth inner circumferential surface 60 is located in the central portion of the joint body 21 in the axial direction, and is a portion common to one joint portion 31 and the other joint portion (not shown).

[0025] The fourth inner circumferential surface 58 and the fourth step surface 59 form a recess 61. The recess 61 is located on the inner circumferential edge of the third step surface 57. The recess 61 is recessed axially from the third step surface 57 toward the rear in the pipe insertion direction. The recess 61 is provided around the entire circumferential direction of the fitting body 21. The recess 61 is annular. The recess 61 includes the fourth inner circumferential surface 58 and the fourth step surface 59 that are L-shaped in cross section, and a space extending in the axial direction on an axis corresponding to the fourth inner circumferential surface 58 and the fourth step surface 59. Note that the recess 61 may be omitted.

[0026] The joint body 21 is formed, for example, by injection molding of a synthetic resin material, or by cutting, casting, or forging of a metal material.

[0027] The nut member 22 has a cylindrical portion 72 , a stepped portion 73 , and a socket portion 74 . The cylindrical portion 72 is cylindrical and has an axis O as its center, and has an internal thread 71 formed on its inner periphery to be threaded onto the external thread 45 of the joint body 21 . The stepped portion 73 extends radially inward from the front side of the cylindrical portion 72 in the pipe insertion direction. The socket portion 74 is cylindrical and centered on the axis O, and extends from the radially inner side of the stepped portion 73 to the opposite side of the cylindrical portion 72 in the axial direction, that is, toward the front side in the pipe insertion direction.

[0028] The nut member 22 is threaded onto the male thread 45 of the joint body 21 at the female thread 71 of the tubular portion 72, and at that time, the end face of the tubular portion 72 on the rear side in the pipe insertion direction abuts against the flange portion 46 of the joint body 21. The inner diameter of the socket portion 74 is slightly larger than the outer diameter of the pipe P. The nut member 22 is formed, for example, by injection molding of a synthetic resin material, or by cutting, casting, or forging of a metal material.

[0029] The radially inner side of the receiving portion 74, on the side opposite the axial cylindrical portion 72, i.e., on the front side in the pipe insertion direction, forms a tapered surface 77 that increases in diameter toward the side opposite the cylindrical portion 72, and the portion on the axial cylindrical portion 72 side forms a cylindrical surface 78. Therefore, the inner circumferential surface of the nut member 22 is formed so that the diameter decreases from the front side in the pipe insertion direction toward the back side in the pipe insertion direction. This makes it easier to insert the inner core 28 into the nut member 22 and the pipe P into the nut member 22 when connecting pipes.

[0030] The multiple anti-slip rings 23 have the same shape and include a circular, specifically a perforated circular flat plate-shaped base portion 81, and a tapered locking plate portion 82 that extends axially while reducing in diameter from the inner side of the base portion 81.

[0031] As shown in FIG. 2, the width of the base plate portion 81 in the radial direction is constant over the entire circumference.

[0032] The locking plate portion 82 has a plurality of bent pieces 92 and bent pieces 93 arranged in the circumferential direction of the base plate portion 81 with slits 91 between them. The bent pieces 92 and 93 of the locking plate portion 82 are arranged alternately in the circumferential direction of the base plate portion 81. That is, the locking plate portion 82 is arranged in the circumferential direction of the base plate portion 81 in the following order: bent piece 92, slit 91, bent piece 93, slit 91, bent piece 92, slit 91, bent piece 93, ... The slit 91 extends from between adjacent bent pieces 92 and 93 to a predetermined position on the inner circumferential side of the base plate portion 81.

[0033] The bent pieces 92 and 93 extend radially inward at an angle relative to the axial direction from the inner circumferential side of the base plate portion 81. The bent piece 92 has a main plate portion 94 that extends radially inward at an angle relative to the axial direction from the inner circumferential side of the base plate portion 81, and a protrusion 95 that protrudes in the extension direction of the main plate portion 94 from the circumferential center of the retaining ring 23 at the radially inner end of the main plate portion 94. The bent piece 93 has a shape that does not have the protrusion 95 of the bent piece 92, i.e., the shape of the main plate portion 94.

[0034] As shown in FIG. 1 , each of the multiple retaining rings 23 is oriented so that the locking plates 82 extend from the base plate 81 toward the rear in the pipe insertion direction and are fitted onto the tubular portion 72 of the nut member 22 at the base plate 81. Therefore, the outer diameter D1 of the retaining ring 23 is larger than the inner diameter of the fitting body 21, specifically the inner diameter D2 of the first inner circumferential surface 51 at the end of the accommodation portion 42 of the fitting body 21 on the front side in the pipe insertion direction, and slightly smaller than the inner diameter of the tubular portion 72 of the nut member 22. Furthermore, the inner diameter of the locking plates 82 of the retaining ring 23 before the pipe P is inserted is smaller than the outer diameter of the pipe P. The retaining ring 23 is a press-molded product made of metal, but may also be formed by injection molding of a synthetic resin material, or by cutting, casting, or forging of a metal material. The anti-slip ring 23 is provided in the accommodating recess 48, and when the pipe P is inserted into the pipe fitting 11, the radially inner end of the locking plate portion 82, i.e., the end opposite the base plate portion 81 of the bent pieces 92, 93, contacts and bites into the outer surface of the pipe P, preventing the pipe P from slipping out.

[0035] The base member 24 is annular and fits into the tubular portion 72 of the nut member 22. Therefore, the outer diameter of the base member 24 is larger than the inner diameter of the first inner circumferential surface 51 at the end of the fitting body 21 on the front side in the pipe insertion direction, and slightly smaller than the inner diameter of the tubular portion 72. The inner diameter of the base member 24 is larger than the inner diameter of the base plate portion 81 of the retaining ring 23. The base member 24 is formed, for example, by injection molding of a synthetic resin material, or by cutting, casting, or forging of a metal material. Both axial end surfaces of the base member 24 are flat and extend perpendicular to the axial direction.

[0036] Spacer 25 is annular, fits over first inner circumferential surface 51 and second inner circumferential surface 53 of installation recess 48, and abuts against first step surface 52. The inner diameter of the portion of spacer 25 that fits over first inner circumferential surface 51 in the axial direction is larger than the inner diameter of base plate portion 81 of retaining ring 23, and the inner diameter of the portion that fits over second inner circumferential surface 53 in the axial direction is slightly larger than the outer diameter of pipe P. Spacer 25 is formed, for example, by injection molding of a synthetic resin material, or by cutting, casting, or forging of a metal material.

[0037] One retaining ring 23(a) (second retaining ring) with a locking plate portion 82 disposed on the rear side in the pipe insertion direction abuts at its base plate portion 81 against the front side in the pipe insertion direction of the joint main body 21 and the spacer 25 that is fitted onto the first inner circumferential surface 51 and the second inner circumferential surface 53 of the installation recess 48 of the joint main body 21 and abuts against the first step surface 52, the base member 24 abuts against the front side in the pipe insertion direction of this base plate portion 81, and the other retaining ring 23(b) (first retaining ring) with a locking plate portion 82 disposed on the rear side in the pipe insertion direction abuts at its base plate portion 81 against the front side in the pipe insertion direction of this base member 24. The retaining ring 23(a), the base member 24, and the retaining ring 23(b) are fitted radially inside the tubular portion 72, and the nut member 22 screws onto the male thread 45 of the joint main body 21 via the female thread 71. This results in the anti-slip ring 23(a), base member 24 and anti-slip ring 23(b) being placed on the front side of the fitting body 21 in the pipe insertion direction, and the front side of the anti-slip ring 23(b) in the pipe insertion direction is covered by the stepped portion 73 of the nut member 22.

[0038] Therefore, two retaining rings 23(a) and 23(b) are provided in the joint portion 31, spaced apart in the axial direction. Retaining ring 23(b) is arranged on the insertion side of the pipe P, and retaining ring 23(a) is arranged on the opposite side of retaining ring 23(b) from the insertion side of the pipe P. In both retaining rings 23(a) and 23(b), the multiple bent pieces 92 and multiple bent pieces 93 bite into the outer periphery of the pipe P placed in the joint body 21 to prevent it from coming off the pipe joint 11. At that time, the protrusions 95 of the bent pieces 92 are designed to easily bite into the outer periphery of the pipe P.

[0039] An annular seal member 26 is fitted into the second inner circumferential surface 53 of the accommodating recess 48, further back in the pipe insertion direction than the spacer 25. The seal member 26 is a rubber O-ring. The outer diameter of the seal member 26 before being placed within the second inner circumferential surface 53 is larger than the inner diameter of the second inner circumferential surface 53. The inner diameter of the seal member 26 before the pipe P is inserted is smaller than the outer diameter of the pipe P. The seal member 26 is provided in the accommodating recess 48, and when the pipe P is inserted into the fitting portion 31 of the pipe fitting 11, it comes into contact with the outer circumferential surface of the pipe P to seal between the pipe P and the fitting body 21.

[0040] The fitting body 21 and the nut member 22 form an inner core accommodating portion 101. The inner core accommodating portion 101 is a space that accommodates the inner core 28. The inner core accommodating portion 101 is a space that is formed by the fitting body 21 and the nut member 22 and is located on the front side of the fifth inner circumferential surface 60 in the pipe insertion direction. A plurality of retaining rings 23, a base member 24, a spacer 25, and a seal member 26 are arranged approximately in the axial center of the inner core accommodating portion 101. The plurality of retaining rings 23 and the seal member 26 surround the pipe P so as to be in close contact with the pipe P when the pipe P is inserted into the pipe fitting 11. The base member 24 and the spacer 25 surround the pipe P when the pipe P is inserted into the pipe fitting 11. The first inner circumferential surface 51, the first step surface 52, the second inner circumferential surface 53, the second step surface 54, the third inner circumferential surface 55, the engagement groove 56, the third step surface 57 and the fourth inner circumferential surface 58 are formed in the inner core accommodating portion 101.

[0041] The inner core 28 is formed in a hollow cylindrical shape extending in the axial direction, and both axial ends are open. The inner core 28 is an injection-molded product of a synthetic resin material, but may also be formed by cutting, casting, or forging a metal material. The inner core 28 has a cylindrical inner support portion 111 and an outer arrangement portion 112 that is arranged axially outward of the inner support portion 111. The entire inner core 28 is formed seamlessly as a single unit.

[0042] The inner support portion 111 is fitted into the tip portion of the pipe P in the insertion direction into the pipe fitting 11 and supports the tip portion of the pipe P from the radially inside. Therefore, the inner support portion 111 suppresses radial deformation of the tip portion of the pipe P.

[0043] The outer portion 112 is arranged axially outward of the tip face of the pipe P in the insertion direction into the pipe joint 11, that is, the tip face on the far side in the pipe insertion direction, and abuts against this tip face.

[0044] The outer diameter of the inner support portion 111 is smaller than the inner diameter of the in-core accommodating portion 101. The inner support portion 111 can be accommodated in the in-core accommodating portion 101. The inner support portion 111 has a first end portion 115 and a second end portion 116. The first end portion 115 is the end portion of the inner support portion 111 opposite the outer disposed portion 112 in the axial direction. The second end portion 116 is the end portion of the inner support portion 111 on the outer disposed portion 112 side in the axial direction. The inner support portion 111 of the in-core 28 is inserted axially from the first end portion 115 side into the tip portion of the pipe P in the insertion direction into the pipe fitting 11. With the inner support portion 111 positioned inside the pipe P, the pipe P is in close contact with the inner support portion 111 and is surrounded by the pipe P.

[0045] 1 , the incore 28 is arranged in the incore accommodating portion 101 so that the first end 115 is located on the front side in the pipe insertion direction in the axial direction of the fitting body 21. On the other hand, although not shown, when the pipe fitting 11 is stored, the incore 28 is inserted into the incore accommodating portion 101 so that the first end 115 is located on the rear side in the pipe insertion direction in the axial direction of the fitting body 21. The outer diameter of the first end 115 is larger than the inner diameter of the fifth inner circumferential surface 60 and smaller than the inner diameter of the recess 61. As a result, the first end 115 can be arranged in the recess 61 during storage as described above.

[0046] The outer placement portion 112 is provided on one axial end side of the inner support portion 111 and is formed so as to protrude radially outward beyond the inner support portion 111 over the entire circumferential circumference. The inner circumferential surface of the outer placement portion 112 is continuous with the inner circumferential surface of the inner support portion 111. The outer placement portion 112 is annular and formed over the entire circumferential circumference of the incore 28. The outer diameter of the outer placement portion 112 is smaller than the bottom diameter of the engagement groove 56 and larger than the inner diameter of the third inner circumferential surface 55 of the joint body 21. The outer placement portion 112 is able to fit into and engage with the engagement groove 56.

[0047] Although not shown in the drawings, when the pipe fitting 11 is stored, the outer placement portion 112 may be inserted into the inner core accommodating portion 101 so as to be positioned on the front side in the pipe insertion direction in the axial direction of the fitting body 21. In this case, it is preferable that the outer placement portion 112 does not protrude outward in the axial direction from the inner core accommodating portion 101 (nut member 22).

[0048] 1 , even if the outer placement portion 112 is positioned at the rear in the pipe insertion direction, the outer placement portion 112 is not positioned within the recess 61. At this time, the outer placement portion 112 enters and engages with the engagement groove 56. In this state, when the tip surface of the outer placement portion 112 on the axial side opposite the inner support portion 111 abuts against the third step surface 57, further movement toward the rear in the pipe insertion direction is restricted. Also, in this state, when the back surface of the outer placement portion 112 on the axial side of the inner support portion 111 abuts against the wall surface of the engagement groove 56 on the third inner circumferential surface 55 in the axial direction, movement toward the front in the pipe insertion direction is restricted, and the outer placement portion 112 does not easily come out of the outer structural body 30.

[0049] Furthermore, the outer peripheral surface of the outer placement portion 112 on the radially outer side is formed so that when the pipe P is connected to the pipe fitting 11, the diameter decreases as it moves toward the rear in the pipe insertion direction. Therefore, when connecting the pipes, it is easy to insert the inner core 28 from the outer placement portion 112 into the outer component 30 including the nut member 22, the retaining ring 23(b), the spacer 25, the retaining ring 23(a) and the sealing member 26.

[0050] The synthetic resin material applicable to the joint body 21, nut member 22, base member 24, spacer 25, and incore 28 can be selected arbitrarily based on the quality design appropriate for the application, such as cross-linked polyethylene, polybutene, polyvinyl chloride (PVC), polysulfone resin (PSU), polycarbonate resin (PC), polyamide resin (PA), polyacetal resin (POM), polyphenylsulfone resin (PPSU), polyphenylene sulfide resin (PPS), glass fiber reinforced PPS, polyvinylidene fluoride (PVDF), etc. Other processing methods such as cutting and fusion may also be used.

[0051] The metal materials applicable to the joint body 21, nut member 22, retaining ring 23, base member 24, spacer 25, and incore 28 can be selected arbitrarily based on the quality design appropriate for the application, including stainless steel, low-alloy steel, carbon steel, low-temperature carbon steel, low-temperature alloy steel, brass, gunmetal, aluminum alloy, magnesium alloy, etc.

[0052] The material of the sealing member 26 may be rubber material such as ethylene propylene diene rubber (EPDM), fluororubber (FKM), vinyl methyl silicone rubber (VMQ), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), or chloroprene rubber (CR).

[0053] Next, a piping connection method for connecting the pipe P to the pipe joint 11 will be described. During storage of the pipe fitting 11 before the pipe P is connected, the incore 28 is accommodated in the incore accommodating portion 101 of the outer component 30. Although not shown, specifically, the outer placement portion 112 of the incore 28 is positioned forward in the pipe insertion direction relative to the inner support portion 111 and is fitted into the socket portion 74 of the nut member 22, and the first end 115 of the inner support portion 111 is accommodated in the recess 61 of the fitting body 21. The installer removes the incore 28 in this state by pulling it out toward the front in the pipe insertion direction from the incore accommodating portion 101 of the outer component 30, and then performs an incore attachment step in which, for example, the inner support portion 111 is inserted into the tip of the pipe P on the connection side to the pipe fitting 11 to attach the incore 28 to the pipe P.

[0054] By performing this incore attachment step, the pipe P with the incore 28 attached is inserted into the outer component 30 from the front in the pipe insertion direction, with the outer portion 112 of the incore 28 leading the way, into the socket portion 74 of the nut member 22, and then into the installation recess 48 of the joint body 21. Then, the outer portion 112 of the incore 28 passes through the socket portion 74 of the nut member 22, passes through the retaining ring 23(b), the base member 24, the retaining ring 23(a), the spacer 25, the seal member 26, and the third inner circumferential surface 55 of the joint body 21, and engages with the engagement groove 56. Then, the retaining rings 23(a), 23(b) and the seal member 26 come into contact with the outer circumferential surface of the pipe P.

[0055] The pipe joint 11 of the first embodiment described above has a plurality of retaining rings 23 arranged between the joint body 21 and the nut member 22, and therefore the ultimate pull-out strength in the direction in which the pipe P is pulled out can be improved. Furthermore, since the outer diameter D1 of the anti-slip ring 23 is larger than the inner diameter D2 of the joint body 21, the distance from the radial outer end of the slit 91 of the anti-slip ring 23 to the radially outer outer end of the anti-slip ring 23, i.e., the radial length of the portion of the base portion 81 of the anti-slip ring 23 where the slit 91 is not formed, can be secured. Here, high stress is generated at the radially outer end of the slit in the retaining ring, and fatigue cracks originate from this end. The cross-sectional area of ​​the retaining ring 23, when the portion of the base plate portion 81 where the slits 91 are not formed is cross-sectionally taken along a plane including the central axis of the retaining ring 23, affects the pull-out fatigue strength of the pipe fitting 11. Specifically, the larger this cross-sectional area, the higher the pull-out fatigue strength of the retaining ring 23 and the more likely fatigue cracks will occur in the retaining ring 23. Therefore, assuming the thickness of the base plate portion 81 is the same, the radial length of the portion of the base plate portion 81 where the slits 91 are not formed—in other words, the distance from the radially outer end of the slit 91 in the retaining ring 23 to the radially outermost end of the retaining ring 23—affects the pull-out fatigue strength of the pipe fitting 11. Specifically, if the distance from the radially outer end of the slit to the radially outermost end of the retaining ring becomes shorter, the pull-out fatigue strength of the retaining ring decreases, making the retaining ring more susceptible to fatigue cracking. In contrast, in the pipe fitting 11, the outer diameter of the retaining ring 23 is larger than the inner diameter of the fitting body 21, so it is possible to ensure a sufficient distance from the radially outer end of the slit 91 of the retaining ring 23 to the radially outermost end of the retaining ring 23. This makes it possible to improve the pull-out fatigue strength of the retaining ring 23, and ultimately the pull-out fatigue strength of the pipe fitting 11. Therefore, the reliability can be improved.

[0056] [Second embodiment] A pipe joint according to a second embodiment of the present invention will be described below, mainly with reference to FIG. 3, focusing on the differences from the first embodiment.

[0057] As shown in Fig. 3, the pipe fitting 11A of the second embodiment has a joint portion 31A that is partially different from the joint portion 31 of the pipe fitting 11 of the first embodiment, instead of the joint portion 31. The pipe fitting 11A of the second embodiment has an outer constituent body 30A that is partially different from the outer constituent body 30 of the pipe fitting 11 of the first embodiment, instead of the outer constituent body 30. The joint portion 31A and the outer constituent body 30A have a base member 24A that is partially different from the base member 24 of the pipe fitting 11 of the first embodiment, instead of the base member 24.

[0058] The base member 24A has an annular main body portion 121, whose both axial end surfaces are flat and extend perpendicular to the axial direction. The base member 24A fits into the cylindrical portion 72 of the nut member 22, and an annular protrusion portion 122 provided on the inner periphery of the main body portion 121. The protrusion portion 122 protrudes from the main body portion 121 to one axial side and radially inward. The protrusion portion 122 has an inner inclined surface 123 facing radially inward and an outer inclined surface 124 facing radially outward. The inner inclined surface 123 is a tapered surface that extends from one axial end of the main body portion 121 toward the other end while decreasing in diameter to a position beyond the other end. The outer inclined surface 124 is a tapered surface that extends from the other axial end of the main body portion 121 while decreasing in diameter.

[0059] The outer diameter of the base member 24A, i.e., the outer diameter of the main body portion 121, is larger than the inner diameter of the first inner circumferential surface 51 at the end on the inner periphery of the fitting body 21 that is closer to the pipe insertion direction, and is slightly smaller than the inner diameter of the tubular portion 72. The inner diameter of the base member 24A, i.e., the inner diameter of the protruding portion 122, is smaller than the inner diameter of the base plate portion 81 of the retaining ring 23, and is slightly larger than the outer diameter of the pipe P.

[0060] In the pipe fitting 11A, the fitting portion 31A and the outer component 30A have a nut member 22A that is partially different from the nut member 22 of the first embodiment, instead of the nut member 22. The nut member 22A has a stepped portion 73A that is partially different from the stepped portion 73, instead of the stepped portion 73. The stepped portion 73A has an annular protruding portion 131 that protrudes radially inward from the end face on the rear side in the pipe insertion direction from this end face toward the rear in the pipe insertion direction. The protruding portion 131 has an inclined surface 132 that faces the rear in the pipe insertion direction. The inclined surface 132 is a tapered surface that extends while reducing in diameter toward the rear in the pipe insertion direction.

[0061] One retaining ring 23(a), with locking plate 82 located at the rear in the pipe insertion direction, abuts at base plate 81 on the front side in the pipe insertion direction of joint body 21 and spacer 25 when disposed within joint body 21, and base member 24A, with protrusion 122 protruding rearward in the pipe insertion direction, abuts at main body 121 on the front side in the pipe insertion direction of base member 24A, and the other retaining ring 23(b), with locking plate 82 located at the rear in the pipe insertion direction, abuts at base plate 81 on the front side in the pipe insertion direction of main body 121 of base member 24A. Then, retaining ring 23(a), base member 24A, and retaining ring 23(b) are fitted radially inside tubular portion 72, and the female thread 71 of nut member 22 is screwed onto the male thread 45 of joint body 21. The base member 24A has a protrusion 122 disposed in the gap between the locking plate portion 82 of the retaining ring 23(a) and the locking plate portion 82 of the retaining ring 23(b). The protrusion 122 protrudes further in the pipe insertion direction than the end face of the base plate portion 81 of the retaining ring 23(a) on the front side in the pipe insertion direction.

[0062] According to the pipe fitting 11A of the second embodiment, the protrusion 122 of the base member 24A protrudes further in the pipe insertion direction than the end face of the base plate portion 81 of the anti-slip ring 23(a) on the front side in the pipe insertion direction, thereby preventing the locking plate portion 82 of the anti-slip ring 23(a) from turning over.

[0063] Furthermore, the protrusion 131 of the nut member 22A prevents the locking plate portion 82 of the retaining ring 23(b) from turning over.

[0064] [Third embodiment] A pipe joint according to a third embodiment of the present invention will be described below, mainly with reference to FIG. 4, focusing on differences from the first and second embodiments.

[0065] As shown in Fig. 4, the pipe fitting 11B of the third embodiment has a joint portion 31B that is partially different from the joint portion 31A of the pipe fitting 11A of the second embodiment, instead of the joint portion 31A. The pipe fitting 11B of the third embodiment has an outer constituent body 30B that is partially different from the outer constituent body 30A of the pipe fitting 11A of the second embodiment, instead of the outer constituent body 30A. The joint portion 31B and the outer constituent body 30B have multiple, specifically two, base members 24A. One base member 24A(a) is provided between the retaining ring 23(a) and the retaining ring 23(b), as in the second embodiment, and the other base member 24A(b) is provided on the front side of the retaining ring 23(b) in the pipe insertion direction.

[0066] In the pipe fitting 11B, a fitting portion 31B and an outer component 30B have a nut member 22B that is partially different from the nut member 22 of the first embodiment instead of the nut member 22. The nut member 22B has a cylindrical portion 72B that is longer in the axial direction than the cylindrical portion 72A to accommodate the base member 24A(b), and a stepped portion 73B that does not have the protruding portion 131 of the stepped portion 73A.

[0067] One of the anti-slip rings 23(a), with the locking plate portion 82 positioned at the rear side in the pipe insertion direction, abuts at the base plate portion 81 on the front side in the pipe insertion direction of the joint main body 21 and the spacer 25 when arranged within the joint main body 21, and the base member 24A(a) with the protrusion 122 protruding toward the rear side in the pipe insertion direction abuts at the main body portion 121 on the front side in the pipe insertion direction of this base member 81, and the other anti-slip ring 23(b), with the locking plate portion 82 positioned at the rear side in the pipe insertion direction, abuts at the base plate portion 81 on the front side in the pipe insertion direction of the main body portion 121 of this base member 24A(a), and the base member 24A(b) with the protrusion 122 protruding toward the rear side in the pipe insertion direction abuts at the main body portion 121 on the front side in the pipe insertion direction of this base member 24A(a). The retaining ring 23(a), base member 24A(a), retaining ring 23(b), and base member 24A(b) are fitted radially inside the tubular portion 72B, and the nut member 22B is threadedly engaged with the male threads 45 of the fitting body 21 via the female threads 71. The base member 24A(a) has a protrusion 122 disposed in the gap between the locking plate portion 82 of the retaining ring 23(a) and the locking plate portion 82 of the retaining ring 23(b). The protrusion 122 of the base member 24A(a) protrudes further in the pipe insertion direction than the front end face of the base plate portion 81 of the retaining ring 23(a). The base member 24A(b) has a protrusion 122 protruding further in the pipe insertion direction than the front end face of the base plate portion 81 of the retaining ring 23(b).

[0068] According to the pipe fitting 11B of the third embodiment, the protrusion 122 of the base member 24A(a) protrudes further in the pipe insertion direction than the front end face in the pipe insertion direction of the base plate portion 81 of the retaining ring 23(a), thereby preventing the locking plate portion 82 of the retaining ring 23(a) from turning over inside out. Also, the protrusion 122 of the base member 24A(b) protrudes further in the pipe insertion direction than the front end face in the pipe insertion direction of the base plate portion 81 of the retaining ring 23(b), thereby preventing the locking plate portion 82 of the retaining ring 23(b) from turning over inside out.

[0069] [Fourth embodiment] A pipe joint according to a fourth embodiment of the present invention will be described below, mainly with reference to FIG. 5, focusing on the differences from the first embodiment.

[0070] As shown in FIG. 5 , a pipe fitting 11C of the fourth embodiment has a joint portion 31C that is partially different from the joint portion 31 of the pipe fitting 11 of the first embodiment, instead of the joint portion 31. The pipe fitting 11 of the fourth embodiment has an outer construct 30C that is partially different from the outer construct 30 of the pipe fitting 11 of the first embodiment, instead of the outer construct 30. The joint portion 31C and the outer construct 30C have a joint main body 21C that is partially different from the joint main body 21, instead of the joint main body 21. The joint main body 21C does not have the engagement groove 56 of the pipe fitting 11, and has a third inner circumferential surface 55C that is different from the third inner circumferential surface 55 in this respect, and a third step surface 57C that is different from the third step surface 57 in this respect. The third inner circumferential surface 55C extends to the third step surface 57C. The joint portion 31C has an incore 28C that is partially different from the incore 28 instead of the incore 28. The outer diameter of the outer placement portion 112 of the incore 28C is larger than the inner diameter of the pipe P and is equal to or smaller than the outer diameter of the pipe P.

[0071] In the pipe fitting 11C, the pipe P with the incore 28C attached thereto is inserted from the front in the pipe insertion direction, with the outer portion 112C of the incore 28C leading the way, into the outer component 30C, the socket portion 74 of the nut member 22, and the installation recess 48 of the fitting body 21C in that order. Then, the outer portion 112C of the incore 28C passes through the socket portion 74 of the nut member 22, the retaining ring 23(b), the base member 24, the retaining ring 23(a), the spacer 25, the seal member 26, and the third inner circumferential surface 55C of the fitting body 21C, and abuts against the third step surface 57C. Then, the retaining rings 23(a), 23(b) and the seal member 26 come into contact with the outer circumferential surface of the pipe P.

[0072] The pipe joint 11C of the fourth embodiment having such a configuration makes it easy to insert the pipe P with the in-core 28C attached into the outer constituent body 30C.

[0073] The modifications of the fourth embodiment to the first embodiment can also be applied to the second embodiment, and can also be applied to the third embodiment. [Example]

[0074] (Pull-out strength comparison) The difference in pull-out strength between a pipe joint with a single-ring structure (comparison example) and a pipe joint with a double-ring structure (example) was examined. Tensile test was conducted on a φ13 pipe fitting. Test conditions: The sample connected to the pipe fitting was pulled at 20 mm / min using a Tensilon universal testing machine. Test sample: Metal male adapter + 250mm pipe + 1 retaining ring structure / Pipe fitting with 2 retaining ring structure + 250mm pipe + metal male adapter The results are shown in Table 1.

[0075] [Table 1]

[0076] As is clear from Table 1, the pipe joint with the two-ring structure of the example has a pull-out strength of 1.72 kN, which is stronger than the 1.57 kN of the pipe joint with the single-ring structure of the comparative example. Therefore, it is clear that in order to improve the pull-out strength, it is preferable that the pipe joint have the two-ring retaining structure of the example rather than the one-ring retaining structure of the comparative example.

[0077] Here, because there is a trade-off between the pull-out strength and pull-out fatigue strength of the pipe joint and the pipe insertion force, it is preferable to select the material of the retaining ring as follows: For example, Table 2 shows the properties of SUS (stainless steel), and if SUS is used as the material for the retaining ring, it is preferable to select it as follows:

[0078] [Table 2]

[0079] When inserting a pipe with a two-ring retaining structure, the force required to insert the pipe is high, so it is recommended that the retaining ring be made of SUS (stainless steel) with a hardness of 430HV or less. To maintain the pull-out strength and pull-out fatigue strength of the retaining ring, the yield strength is 470N / mm 2 Over 780N / mm 2 The above SUS is desirable. Therefore, it is desirable to use a SUS within the range enclosed by the dashed line in Table 2.

[0080] (Comparison of pulling fatigue strength) A comparison was made between a pipe fitting (comparative example) having a structure in which a retaining ring with an outer diameter smaller than the inner diameter of the fitting body is located radially inside the fitting body, and a pipe fitting (example) having a structure in which a retaining ring with an outer diameter larger than the inner diameter of the fitting body is located on the front side of the fitting body in the pipe insertion direction. A tensile fatigue test to measure the pull-out fatigue strength was performed using an axial tensile force equivalent to 0.75 MPa x a safety factor of 3. A 20A fitting was used in the tensile fatigue test, and the test load was set to 0.1 kN to 1.29 kN. A repeated tensile load was applied, and the frequency of the load was set to 6 Hz. The test target value was set to 3 million cycles. This target value corresponds to a housing life of 75 years or more. The results are shown in Table 3.

[0081] [Table 3]

[0082] As described above and shown in Table 3, the tensile fatigue strength, which is the draw fatigue strength, is affected by the cross-sectional area of ​​the non-slit portion of the base plate of the retention ring when the cross section is taken along a plane including the central axis of the retention ring. Specifically, the larger this cross-sectional area, the higher the draw fatigue strength of the retention ring and the more susceptible it is to fatigue cracking. Therefore, assuming a given thickness of the base plate, the radial length of the non-slit portion of the base plate—in other words, the distance from the radially outer edge of the slit to the radially outermost edge of the retention ring—affects the draw fatigue strength of the pipe fitting. Specifically, as the distance from the radially outer edge of the slit to the radially outermost edge of the retention ring decreases, the draw fatigue strength of the retention ring decreases, making it more susceptible to fatigue cracking.

[0083] As is clear from Table 3, the pipe fitting of the comparative example did not suffer any breakage in the retaining ring in the tensile fatigue test of 3 million cycles, and exhibited relatively high tensile fatigue strength, achieving a service life equivalent to a residential life of 75 years or more. In contrast, the pipe fitting of the example did not suffer any breakage in the retaining ring even in the tensile fatigue test of 4 million cycles, and exhibited even higher tensile fatigue strength, i.e., drawing fatigue strength, and was found to achieve a service life equivalent to a residential life of 100 years or more.

[0084] This indicates that it is desirable for the outer diameter of the retaining ring to be larger than the inner diameter of the joint body. In other words, the larger the outer diameter of the retaining ring, the higher the pull-out fatigue strength of the retaining ring. However, in order to fit the retaining ring into the pipe joint, the outer diameter of the retaining ring is made smaller than the inner diameter of the nut member.

[0085] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the present invention also includes modifications, combinations, deletions, etc. of the configuration within the scope of the gist of the present invention. For example, the number of retaining rings 23 may be three or more. Furthermore, it goes without saying that the configurations shown in each embodiment can be used in appropriate combinations. [Explanation of symbols]

[0086] 11...pipe joint, 21...joint body, 22...nut member, 23(a)...second retaining ring, 23(b)...first retaining ring, 81...base plate portion, 91...slit, 92, 93...bending piece, P...pipe.

Claims

1. a cylindrical joint body to which a resin pipe is connected; a nut member that is threadedly attached to the joint body; a plurality of retaining rings disposed between the joint body and the nut member, The retaining ring is a circular substrate portion; a plurality of bent pieces arranged in the circumferential direction of the base plate portion with slits between them, the bent pieces extending radially inward from the inner circumferential side of the base plate portion at an angle with respect to the axial direction of the joint body, A pipe fitting whose outer diameter is larger than the inner diameter of the fitting body.

2. The retaining ring is a first retaining ring disposed on the insertion side of the tube; 2. The pipe joint according to claim 1, further comprising: a second retaining ring disposed on the opposite side of the first retaining ring from the insertion side of the pipe.

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