Pipe fittings and inner cores

Abstract

To provide a pipe joint capable of facilitating the mounting of a resin pipe.SOLUTION: The pipe joint includes a joint body into which the resin pipe can be inserted from the axial front side to the depth side, a cylindrical inner core to be internally fitted to a pipe end portion of the resin pipe, a nut that can be screwed onto a male screw of the joint body, a fastening member to be externally fitted to the resin pipe, and a temporary regulation part, the joint body including an inner peripheral face and a deep face, the inner core extending from the deep face to the front side and formed with an insertion space through which the resin pipe can be inserted into a space encircled by the inner peripheral face, the deep face and the outer peripheral face of the inner core. The nut presses the fastening member in the radially internal direction when threaded to the joint body. The diameter of the fastening member is decreased to fasten the resin pipe by the pressure of the fastening member. The temporary regulation part temporarily regulates the insertion of the resin pipe into the axial depth side, and allows the insertion of the resin pipe into the axial depth side with force given to the axial depth side by the fastening of the nut. In the state that the threading of the nut to the joint body is completed, a gap is formed between the pipe end and the deep face.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pipe joint and an inner core used in the pipe joint. [Background technology]

[0002] Pipe joints are used as connecting components for tightly connecting plastic pipes. For example, a plastic pipe joint described in Patent Document 1 is known as such a pipe joint. Specifically, the plastic pipe joint includes a cylindrical joint body into which the plastic pipe is inserted from the front side to the back side in the axial direction and on which a male thread portion is formed on the outer surface; an end-expanded tube with a tapered portion whose minimum diameter is smaller than the inner diameter of the plastic pipe and whose maximum diameter is larger than the inner diameter of the plastic pipe; a resin seal ring, which is an annular body with an inner diameter approximately equal to the outer diameter of the plastic pipe; and a cylindrical cap nut with an internal thread portion on its inner surface that can be threaded onto the male thread portion and a tapered inner surface whose inner diameter decreases from the back side to the front side. The joint body includes an inner peripheral surface that conforms to the outer peripheral surface of the plastic pipe inserted into the cylindrical interior and a stepped surface that protrudes radially inward from the axially back end of the inner peripheral surface. The end-expanded tube includes a flange that can abut against the stepped surface that protrudes radially outward from the maximum diameter portion of the tapered portion.

[0003] A method for connecting pipes using a plastic pipe joint configured as described above is described below. First, a cap nut and a seal ring are attached to the outer periphery of the plastic pipe. Next, the tapered portion of the end-expanded pipe is press-fitted into the plastic pipe until the flange abuts the pipe end, and the plastic pipe with the end-expanded pipe pressed into it is inserted into the joint body until the flange abuts the stepped surface. Then, when the cap nut is screwed onto the male thread, the tapered inner peripheral surface of the seal ring presses toward the axial center, pressing the plastic pipe radially inward from the outer peripheral surface, firmly sealing the plastic pipe and the joint body. Furthermore, because the outer diameter of the flange is larger than the inner diameter of the seal ring, the flange engages with the seal ring, preventing it from coming loose even when tensile force is applied to the plastic pipe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-79750 Summary of the Invention [Problem to be solved by the invention]

[0005] The pipe fitting described in Patent Document 1 allows a plastic pipe to be attached to the pipe fitting by abutting the flange attached to the pipe end against a stepped surface and threading the cap nut onto the fitting body. When this occurs, the cap nut pushes the seal ring and the plastic pipe pressed against the seal ring toward the axial depth of the fitting body. However, the plastic pipe is restricted from advancing further into the fitting body by the stepped surface, preventing it from moving further into the fitting body. Therefore, when the cap nut is threaded onto the fitting, a reaction force is applied to the plastic pipe due to the stepped surface restricting its advance, increasing the tightening torque of the cap nut and making it difficult to attach the plastic pipe to the pipe fitting.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a pipe joint that can easily attach a resin pipe. [Means for solving the problem]

[0007] The pipe joint of the present invention comprises a cylindrical joint body having an external thread formed on its outer peripheral surface, into which a plastic pipe can be inserted from the front side to the rear side in the axial direction, a cylindrical inner core fitted to the pipe end portion of the plastic pipe, a nut that can be screwed onto the external thread of the joint body, a fastening member that can be fitted to the outside of the plastic pipe, and a temporary restricting portion, wherein the joint body has an inner peripheral surface that faces the outer peripheral surface of the inserted plastic pipe, and a rear surface that extends radially inward from the rear end of the inner peripheral surface, and the inner core is provided so as to extend from the rear surface toward the front side, and the plastic pipe can be inserted into a space surrounded by the inner peripheral surface, the rear surface, and the outer peripheral surface of the inner core. An insertion space is formed, the nut has a tightening member pressing portion that is arranged so as to be able to press the tightening member inward radially when screwed onto the fitting body, the tightening member is configured to reduce in diameter so as to tighten the plastic pipe when pressed by the tightening member pressing portion, the temporary regulating portion contacts the pipe end of the plastic pipe midway along the axial direction of the insertion space to temporarily restrict insertion of the plastic pipe toward the rear in the axial direction, and allows insertion of the plastic pipe toward the rear in the axial direction by the force toward the rear in the axial direction caused by tightening the nut, and is configured so that a gap is formed between the pipe end and the rear face when the nut is completely screwed onto the fitting body.

[0008] The inner core of the present invention comprises a cylindrical joint body having an external thread formed on its outer peripheral surface, into which a plastic pipe can be inserted from the front side to the back side in the axial direction; a nut that can be threaded onto the external thread of the joint body; and a fastening member that can be fitted onto the plastic pipe. The joint body comprises an inner peripheral surface that faces the outer peripheral surface of the inserted plastic pipe, and a back surface that extends radially inward from the back end of the inner peripheral surface and forms, together with the inner peripheral surface, an insertion space into which the plastic pipe is inserted. The nut comprises a fastening member pressing portion that can press the fastening member radially inward when threaded onto the joint body, and the fastening member reduces in diameter to fasten the plastic pipe by pressing the fastening member pressing portion. an inner core for use in a pipe joint configured as described above, the inner core being formed in a cylindrical shape to be fitted into the pipe end portion of the plastic pipe, and configured to be arranged in the insertion space so as to extend from the back side to the front side; and further comprising: a temporary restricting portion that contacts the pipe end of the plastic pipe at an axial midpoint of the insertion space to temporarily restrict insertion of the plastic pipe toward the back side in the axial direction, and allows insertion of the plastic pipe toward the back side in the axial direction by a force toward the back side in the axial direction caused by tightening the nut; and a back surface abutting portion that abuts against the back surface, and the temporary restricting portion is configured so that a gap is formed between the pipe end and the back surface abutting portion when the nut is completely screwed onto the joint body.

[0009] The present invention also provides an inner core for use in a pipe joint, which is cylindrical and has an external thread formed on its outer peripheral surface, and into which a plastic pipe can be inserted from the front side to the back side in the axial direction; a nut that can be threaded onto the external thread of the joint body; and a fastening member that can be fitted onto the plastic pipe, wherein the joint body has an inner peripheral surface that faces the outer peripheral surface of the inserted plastic pipe, and a back surface that extends radially inward from the back end of the inner peripheral surface and forms, together with the inner peripheral surface, an insertion space into which the plastic pipe is inserted, and the nut has a fastening member pressing portion that is provided so as to be able to press the fastening member radially inward when threaded onto the joint body, and the fastening member is an inner core for use in a pipe joint, which is configured to reduce the diameter of the plastic pipe so as to fasten the plastic pipe by pressing the fastening member pressing portion. The core is formed in a cylindrical shape to be fitted into the pipe end portion of the plastic pipe and is arranged in the insertion space so as to extend from the rear side toward the front side, and comprises: a core body that is formed so as to extend from the core body to the rear side toward the front side; a temporary regulating portion that continues from the core body to the rear side; and an insertion guide portion that extends from the temporary regulating portion to the rear side, wherein the temporary regulating portion is composed of a stepped portion that has a regulating surface that extends radially outward from the outer peripheral surface of the core body and is formed with a step on the radially outer side of the core body, and the regulating surface abuts against the pipe end of the plastic pipe inserted into the insertion space, thereby temporarily restricting the insertion of the plastic pipe toward the rear side in the axial direction, and the axial force toward the rear side caused by tightening the nut allows the plastic pipe to be inserted further axially than the temporary regulating portion.

[0010] In addition, the core body can have a tapered outer surface whose outer diameter increases from the front side to the back side in the axial direction, and the outer surface of the insertion guide portion can be configured to have a surface that has a smaller angle with respect to the axial direction than the tapered outer surface.

[0011] In addition, the outer diameter of the axial front end of the core body can be smaller than the inner diameter of the plastic tube, and can be configured to allow the plastic tube manually inserted by an operator to be inserted up to the temporary restriction portion. [Effects of the Invention]

[0012] According to the pipe joint of the present invention, it is possible to easily attach a resin pipe. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a half cross-sectional view of a pipe joint according to a first embodiment of the present invention. [Figure 2] FIG. 4 is a cross-sectional view showing a state in which a resin pipe is inserted into the pipe joint. [Figure 3] FIG. 4 is a cross-sectional view showing a state in which a resin pipe is attached to the pipe joint. [Figure 4] FIG. 4 is a cross-sectional view showing an inner core of a pipe fitting according to a second embodiment of the present invention. [Figure 5] FIG. 4 is a cross-sectional view showing a state in which a resin pipe is inserted into the pipe joint. [Figure 6] FIG. 10 is a cross-sectional view showing a state in which a resin pipe is inserted into a pipe joint according to a third embodiment of the present invention. [Figure 7] FIG. 4 is a cross-sectional view showing a state in which a resin pipe is attached to the pipe joint. [Figure 8] FIG. 10 is a cross-sectional view showing a state in which a resin pipe is inserted into a pipe joint according to a fourth embodiment of the present invention. [Figure 9] FIG. 4 is a cross-sectional view showing a state in which a resin pipe is attached to the pipe joint. [Figure 10] FIG. 10 is a cross-sectional view showing a state in which a resin pipe is inserted into a pipe joint according to a fifth embodiment of the present invention. [Figure 11] FIG. 4 is a cross-sectional view showing a state in which a resin pipe is attached to the pipe joint. DETAILED DESCRIPTION OF THE INVENTION

[0014] A pipe joint according to a first embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG.

[0015] As shown in Figure 1, the pipe fitting 1 of the present invention comprises a cylindrical fitting body 2 into which a plastic pipe 7 can be inserted from the front to the back in the axial direction (from the top to the bottom of the paper in Figure 2), a cylindrical inner core 3 fitted into the end portion of the plastic pipe 7, a nut 4, a fastening member 5 that can be fitted onto the outside of the plastic pipe 7, and a temporary regulating portion 6 provided on the inner core 3.

[0016] The joint body 2 is cylindrical and has a male threaded portion 213 formed on its outer circumferential surface that can be threaded onto the nut 4, and a nut receiving portion 214 on its front end surface that can come into contact with the nut 4 once it has been tightened. Specifically, as shown in Figure 2, the joint body 2 has a plastic pipe insertion portion 20, a joint connecting portion 23 that is connected to the rear side of the plastic pipe insertion portion 20, and a joint operating portion 24. The joint body 2 is made of, for example, metal or resin.

[0017] The resin pipe insertion section 20 comprises an annular outer wall 21 having an inner peripheral surface 210 facing the outer surface of the inserted resin pipe 7, and a rear wall 22 extending radially inward from the rear end of the outer wall 21 and having a rear surface 221 on the front side.

[0018] The outer wall 21 is an annular wall formed around the axis of the pipe fitting 1, and is formed with an inner diameter larger than the outer diameter of the plastic pipe 7 to be inserted. Specifically, the outer wall 21 includes a male thread portion 213 formed on the outer peripheral surface, a nut receiving portion 214 formed as a flat surface on the front end surface, and an inner peripheral surface 210, which includes a tapered fastening member abutment surface 211 and a rear inner peripheral surface 212 extending substantially parallel to the axis on the rear side of the fastening member abutment surface 211. As shown in FIG. 2 , the inner peripheral surface 210 of the outer wall 21 is configured to face the outer peripheral surface of the plastic pipe 7 to be inserted into the pipe fitting 1.

[0019] The fastening member abutment surface 211 constitutes the inner circumferential surface 210 from the front side to the middle part. Specifically, the fastening member abutment surface 211 has a tapered shape in which the diameter decreases from the front side to the rear side, and is connected to the rear inner circumferential surface 212 at the smallest diameter part.

[0020] The rear inner circumferential surface 212 is a surface that extends substantially parallel to the axis of the fitting body 2, with the front side connected to the fastening member abutment surface 211 and the rear side connected to the rear surface 221. As shown in FIG. 3, the diameter of the rear inner circumferential surface 212 is larger than the outer diameter of the expanded resin pipe 7 (expanded portion 72), which will be described later. Furthermore, in this first embodiment, the diameter is substantially the same as the minimum diameter of the fastening member abutment surface 211.

[0021] 2, the rear wall 22 is a wall that extends radially inward from the rear end of the outer wall 21. Specifically, the rear wall 22 is an annular wall that extends radially inward beyond the rear inner circumferential surface 212. The rear wall 22 is connected to the outer wall 21 and the inner core 3 on the front side, and is connected to the joint connection portion 23 on the rear side.

[0022] The joint connecting portion 23 is cylindrical and is connected to the rear side of the resin pipe insertion portion 20, allowing the pipe joint 1 to be connected to another pipe joint. Specifically, the joint connecting portion 23 is connected so as to extend from the rear wall 22 toward the rear side. In this first embodiment, the joint connecting portion 23 has a male thread portion 231 formed on its outer circumferential surface, and can be connected to another pipe joint 1 by, for example, threading it into another pipe joint having a female thread portion formed therein. Note that the connection of pipe joints 1 is not limited to threading the joint connecting portions 23 together, and other joining methods such as recess-projection fitting or crimping may also be used.

[0023] 1, the joint operation part 24 has a cylindrical shape with a polygonal outer circumferential surface, and is connected to the outer circumferential surface of the plastic pipe insertion part 20. In other words, the joint operation part 24 is connected to the joint connection part 23 via the plastic pipe insertion part 20. Therefore, by rotating the joint operation part 24 in the circumferential direction using, for example, a hexagonal wrench, the joint connection part 23 rotates, and the joint connection part 23 can be screwed onto another pipe joint.

[0024] As shown in FIG. 2 , the inner core 3 has a cylindrical shape with a smaller outer diameter on the front side than on the back side, allowing it to be fitted into the end portion of the resin pipe 7. The inner core 3 also has an inner core outer peripheral surface 30 that faces the inner surface of the resin pipe 7. Specifically, the inner core 3 is a tube extending from the back wall 22 toward the front side. It includes a core body 3A having a tapered outer surface 31 whose diameter increases from the front side to the back side, a temporary restriction portion 6 connected to the back side of the core body 3A, and a straight portion 3B connected to the back side of the temporary restriction portion 6. The inner core 3 is made of a material, such as a metal, that has sufficient strength to withstand the fastening described below. Furthermore, in this first embodiment, the inner core 3 is integral with the joint body 2. This reduces the number of parts.

[0025] The core body 3A has a tapered shape in which the outer diameter increases from the front side to the back side and is smaller than the inner diameter of the resin tube 7 to be inserted. The core body 3A also has a tapered outer surface 31. That is, the tapered outer surface 31 is the outer peripheral surface on the front side of the inner core 3, and is the outer peripheral surface on the front side of a restricting surface 6A (described later) of the restricting portion 6. The tapered outer surface 31 also has protrusions 310 extending radially outward in the circumferential direction. In this first embodiment, the protrusions 310 are formed in two locations. One protrusion 310 is a front-side protrusion 311 provided at the front end, and the other protrusion 310 is a mid-portion protrusion 312 provided at the mid-portion of the tapered outer surface 31. The tapered outer surface 31 between the two protrusions 310 is an inter-protrusion outer surface 313.

[0026] The protrusions 310 are provided circumferentially around the tapered outer surface 31 so that their outer diameters are smaller than the inner diameter of the plastic pipe 7 to be inserted. Specifically, the front protrusion 311, which is one of the protrusions 310, has a tapered shape in which its outer diameter increases from the front to the back, with its maximum diameter being slightly smaller than the inner diameter of the plastic pipe 7. Therefore, even if the axis of the plastic pipe 7 is misaligned with the axis of the fitting body 2, the tapered shape allows the pipe end 71 of the plastic pipe 7 to be smoothly guided concentrically, making it easy to align the axes. Furthermore, in this first embodiment, the front protrusion 311 has an outer diameter smaller than the inner diameter of the plastic pipe 7, so that it does not create resistance when inserting the plastic pipe 7 into the fitting body 2, and the axes of the fitting body 2 and the plastic pipe 7 can be aligned. Furthermore, the mid-portion protrusion 312 is raised radially outward in an arc shape. Therefore, it easily bites into the plastic pipe 7 when the plastic pipe 7 is pressed against it during tightening, as described below.

[0027] The straight portion 3B is an insertion guide portion that is connected to the rear side of the restricting portion 6 and that guides the insertion of the plastic pipe 7 that has been allowed to be inserted once beyond the restriction of the restricting portion 6. Specifically, the straight portion 3B has a straight outer surface 32 that is parallel to the axial direction and that is connected to the rear side from the restricting surface 6A of the restricting portion 6. This straight outer surface 32 has a substantially constant outer diameter from the front side to the rear side, and in this first embodiment, is connected to the rear surface 221.

[0028] As shown in FIG. 1, an insertion space 11 into which a resin pipe 7 can be inserted is defined by a space surrounded by an inner peripheral surface 210 and a rear surface 221 of the joint body 2 and the outer peripheral surface of the inner core 3.

[0029] As shown in FIG. 2 , the nut 4 can be threaded onto the male thread portion 213 of the joint body 2. Specifically, the nut 4 includes a female thread portion 41 on the inner peripheral surface at the rear side, and a fastening member pressing portion 42 located forward of the female thread portion 41 and capable of pressing the fastening member 5 radially inward when threaded onto the joint body 2. Furthermore, in this first embodiment, the fastening member pressing portion 42 is located forward of the female thread portion 41, and includes a joint abutment portion 43 between the female thread portion 41 and the fastening member pressing portion 42 that can abut against the nut receiving portion 214 when the nut is fully fastened. The minimum inner diameter of the nut 4 is larger than the outer diameter of the plastic pipe 7. Furthermore, as shown in FIG. 1 , the outer peripheral surface of the nut 4 includes a nut operating portion 44 having a polygonal outer surface. The nut operating portion 44 makes it easier to grip the nut 4 by hand or with a fastening tool, thereby facilitating threading of the nut 4 onto the joint body 2.

[0030] The fastening member pressing portion 42 constitutes the front portion of the nut 4, and has a tapered inner surface that decreases in diameter as it approaches the front. That is, the inner surface of the fastening member pressing portion 42 is shaped so that it can press the fastening member 5 in a radially inward direction when the rear side is in contact with the fastening member contact surface 211. Furthermore, the tapered shape of the fastening member pressing portion 42 causes the nut 4 to press the fastening member 5 in a radially inward direction so as to reduce its diameter, while pushing it inward.

[0031] As shown in FIGS. 1 and 2 , the fastening member 5 is a member that can be fitted onto the resin pipe 7, and is an annular member that is disposed between the fastening member contact surface 211 and the fastening member pressing portion 42. Specifically, the fastening member 5 has a shape that can be reduced in diameter by being pressed radially inward, and the inner peripheral surface 51 is provided with a curved portion 511 that curves radially outward. In this first embodiment, the fastening member 5 is formed with a plurality of circumferentially spaced slits 52 that extend from one axial side to a midpoint and from the other axial side to a midpoint. The curved portions 511 and the slits 52 enable the fastening member 5 configured in this way to deform so that both ends (the front end and the back end) are bent radially inward.

[0032] The outer diameter of the axial center portion of the fastening member 5 is larger than the outer diameter of both axial end portions. Furthermore, the fastening member 5 has a symmetrical shape between the front and rear sides of the axial center portion, except for the slit 52. The axial end portions of the fastening member 5 are arranged so that the rear side abuts against the fastening member abutment surface 211 and the front side abuts against the fastening member pressing portion 42.

[0033] The temporary restricting portion 6 is provided in an axially intermediate portion of the insertion space 11 so as to come into contact with the pipe end 71 of the resin pipe 7 and temporarily restrict insertion of the resin pipe 7 toward the inner side in the axial direction. Specifically, the temporary restricting portion 6 is continuous with the inner side of the core body 3A, and is a stepped portion formed radially outward relative to the tapered outer surface 31, and includes a restricting surface 6A that expands radially outward from the tapered outer surface 31. The restricting surface 6A is provided around the entire outer circumferential surface of the inner core 3.

[0034] The restricting surface 6A is configured to temporarily restrict the insertion of the resin pipe 7 by abutting against the pipe end 71 of the resin pipe 7, specifically the inner diameter edge portion 71A, and in this first embodiment, is formed around the circumference as an inclined surface with the inner diameter side on the front side and the outer diameter side on the back side. The temporary restricting portion 6 is also formed so that the outer diameter on the front side is smaller than the inner diameter of the resin pipe 7 and the outer diameter on the back side is larger than the inner diameter of the resin pipe 7. Therefore, the pipe end 71 of the inserted resin pipe 7 abuts against and engages with the restricting surface 6A, temporarily restricting the insertion.

[0035] The step of the temporary restricting portion 6 restricts the insertion of the plastic pipe 7 manually inserted by the operator, and when the nut 4 is tightened, the inner diameter of the plastic pipe 7 expands due to the force toward the rear, allowing the plastic pipe 7 to overcome the step and enter further. That is, the maximum diameter of the temporary restricting portion 6 in this first embodiment is larger than the inner diameter of the plastic pipe 7 by an amount that can temporarily restrict the plastic pipe 7 and that can be overcome by the force toward the rear due to tightening of the nut 4. Furthermore, the temporary restricting portion 6 is configured so that the diameter of the plastic pipe 7 that has once exceeded the temporary restricting portion 6 expands. That is, the temporary restricting portion 6 is configured to have a hardness that can deform the plastic pipe 7.

[0036] Furthermore, the temporary restricting portion 6 is provided further back than the fastening member 5 in the axial direction. Specifically, the temporary restricting portion 6 is provided further back than the rear end of the fastening member 5. The temporary restricting portion 6 is provided at a position separated from the rear face 221 by a distance greater than the axial advance of the plastic pipe 7 due to the fastening of the nut 4. Furthermore, the additional insertion possible region 12, which is a region where the plastic pipe 7 can be inserted from the temporary restricting portion 6 to the rear face 221, is formed so that its radial width is greater than the wall thickness of the plastic pipe 7 (expanded diameter portion 72) expanded by the fastening described below.

[0037] The following describes how to use such a pipe fitting 1. As shown in Figure 2, a plastic pipe 7 is inserted into the insertion space 11, and then the nut 4 is tightened, thereby attaching the plastic pipe 7 to the pipe fitting 1 as shown in Figure 3.

[0038] Specifically, as shown in Figure 2, the plastic pipe 7 is inserted into the fitting body 2 until the pipe end 71 abuts against the restricting portion 6, and the nut 4 is then screwed onto the fitting body 2. As the nut 4 is screwed, the fastening member pressing portion 42 advances axially rearward, and the front portion of the fastening member 5, whose rear side abuts against the fastening member abutment surface 211, is pressed radially inward by the tapered surface of the inner surface of the fastening member pressing portion 42, pushing it rearward. As the fastening member 5 is pressed radially inward, it is simultaneously subjected to a force acting toward the rear in the axial direction of the nut 4 and moves rearward. Then, as shown in Figure 3, the fitting abutment portion 43 abuts against the nut receiving portion 214, completing the fastening process and the plastic pipe 7 is attached to the pipe fitting 1. At this time, the fastening member 5 is deformed so that the front portion bites into the resin pipe 7 more than the rear portion, and the rear side moves inward and further inward than before fastening.

[0039] At this time, as shown in FIG. 3 , the plastic pipe 7 deforms so that the inner surface of the plastic pipe 7 comes into close contact with the outer peripheral surface of the inner core 3. Specifically, as the diameter of the fastening member 5 is reduced by screwing the nut 4, the fastening member 5 comes into close contact with the outer surface of the plastic pipe 7. As the diameter of the fastening member 5 further decreases, the fastening member 5 tightens the plastic pipe 7 and presses the inner surface of the plastic pipe 7 against the outer peripheral surface 30 of the inner core. As a result, the inner surface of the plastic pipe 7 comes into close contact with the tapered outer surface 31, and the protrusions 310 on the tapered outer surface 31 bite into the inner surface of the plastic pipe 7. Furthermore, as the fastening member 5 receives a force from the nut 4 toward the rear in the axial direction, the plastic pipe 7 fastened to the fastening member 5 also receives a force toward the rear in the axial direction. Due to this force toward the rear in the axial direction, the plastic pipe 7 is allowed to temporarily move beyond the restricting portion 6 and enter further, and the pipe end 71 moves further beyond the restricting portion 6. Furthermore, the portion of the plastic pipe 7 that once passes through the restricting portion 6 and advances to the rear (expanded portion 72) is temporarily expanded in diameter by the restricting portion 6. That is, the inner diameter edge 71A of the plastic pipe 7 receives a force toward the rear and moves radially outward along the restricting surface 6A, thereby expanding the diameter of the inner diameter edge 71A. Next, the portion on the front side of the inner diameter edge 71A also moves radially outward by the restricting surface 6A and is expanded in diameter. Furthermore, once the pipe end 71 (inner diameter edge 71A) passes through the restricting portion 6, it is guided by the straight outer surface 32 that continues from the restricting surface 6A to the rear side, and advances smoothly to the rear side. Then, when tightening is completed, the pipe end 71 does not reach the rear surface 221, and a gap 13 remains between the pipe end 71 and the rear surface 221. It should be noted that the movement distance of the pipe end 71 and the advance distance of the nut 4 do not coincide, but rather the pipe end 71 moves toward the rear by, for example, one-third of the advance distance of the nut 4. The relationship between this movement distance and advance distance differs depending on the shape of the clamping member pressing portion 42, etc.

[0040] At this time, the fastening member 5 deforms the resin pipe 7 so as to press it against the inter-protrusion outer surface 313, and the resin pipe 7, which has deformed to enter the inter-protrusion outer surface 313, is locked by the front-side protrusion 311, preventing the resin pipe 7 from slipping out. Also, because the front side of the fastening member 5 is deformed to enter the diameter, the resin pipe 7 is firmly fastened to the inside of the diameter, preventing it from slipping out. Furthermore, the resin pipe 7 is locked by the mid-portion protrusion 312 on the back side of the inter-protrusion outer surface 313, preventing it from slipping out.

[0041] In the pipe fitting 1 configured as described above, the plastic pipe 7 is inserted into the insertion space 11 until the pipe end 71 contacts the restricting portion 6 and insertion is restricted. When the nut 4 is threaded onto the fitting body 2, the clamping member pressing portion 42 presses the clamping member 5 radially inward, causing the clamping member 5 to contract and clamp the plastic pipe 7. If the nut 4 is then advanced further toward the rear, the axial force exerted by the tightening of the nut 4 acts on the plastic pipe 7 via the clamping member 5 that tightens the plastic pipe 7. This causes the restricting portion 6 to temporarily allow the plastic pipe 7 to be inserted further toward the rear, and the plastic pipe 7 is inserted further toward the rear. Specifically, the force exerted toward the rear when the nut 4 is tightened moves the inner diameter edge portion 71A of the plastic pipe 7 toward the rear along the restricting surface 6A, expanding the inner diameter of the plastic pipe 7 and overcoming the step, allowing the plastic pipe 7 to enter further toward the rear. Once the plastic pipe 7 passes through the restricting portion 6, it enters the additional insertion possible area 12 toward the back. Therefore, the force acting on the plastic pipe 7 toward the back in the axial direction due to the tightening of the nut 4 can be absorbed by the plastic pipe 7 moving toward the back, thereby suppressing an increase in the torque required to tighten the nut 4.

[0042] Furthermore, since the restricting portion 6 is positioned between the fastening member 5 and the rear surface 221, the plastic pipe 7 is inserted further into the fastening member 5 and then the insertion is restricted. This allows the pipe end 71 to be positioned further into the fastening member 5, and the fastening member 5, which is pressed radially inward by the nut 4 to reduce its diameter, can reliably fasten the plastic pipe 7, thereby enabling the plastic pipe 7 to be reliably attached to the pipe fitting 1.

[0043] Furthermore, since the restricting portion 6 is temporarily provided on the inner core 3, which is a member fitted inside the resin pipe 7, the insertion of the resin pipe 7 can be reliably restricted temporarily.

[0044] Furthermore, since the temporary regulating portion 6 is located further forward than the rear face 221 by at least the distance that the plastic pipe 7 advances when tightened, there is a gap 13 between the pipe end 71 and the rear face 221 until tightening is complete, and therefore the increase in the torque required to tighten the nut 4 due to contact between the pipe end 71 and the rear face 221 can be suppressed.

[0045] Furthermore, since the additional insertion area 12 is formed with a width greater than the thickness of the resin pipe 7 once it has been expanded by the restricting portion 6, the resin pipe 7 is less likely to encounter resistance once it is further back than the restricting portion 6, allowing for smoother entry, thereby preventing an increase in the torque required to tighten the nut 4.

[0046] Furthermore, the straight outer surface 32, which is the outer peripheral surface of the inner core 3 further back than the portion where the temporary regulating portion 6 is provided, has an outer diameter that is approximately the same as the maximum diameter portion of the temporary regulating portion 6 and is formed with a substantially uniform diameter from the front side to the back side. Therefore, once the resin pipe 7 passes over the temporary regulating portion 6 and enters, it is less likely to encounter resistance when entering the back side, and an increase in the torque required to tighten the nut 4 can be suppressed.

[0047] Furthermore, once the regulating portion 6 is provided in the inner core 3 fitted inside the resin pipe 7, the resin pipe 7 can be expanded in diameter, and the expanded portion 72 of the resin pipe 7 can be engaged with the inner end of the reduced diameter tightening member 5, thereby preventing the resin pipe 7 from coming loose.

[0048] Furthermore, since the regulating surface 6A of the temporary regulating portion 6 is a tapered surface, the pipe end 71 can move smoothly (expand in diameter) along the slope, and the resistance that the plastic pipe 7 receives from the temporary regulating portion 6 can be reduced, thereby reducing the increase in the torque required to tighten the nut 4.

[0049] Furthermore, since the outer diameter of the inner core 3 before the portion where the temporary restricting portion 6 is provided is smaller than the inner diameter of the resin pipe 7, the resin pipe 7 can be easily inserted into the fitting body 2 until the pipe end 71 abuts against the temporary restricting portion 6.

[0050] The first embodiment of the present invention has been described above, but the present invention is not limited to the first embodiment, and various modifications can be made within the scope that does not deviate from the gist of the present invention.

[0051] For example, the temporary restricting portion 6 has been described as being configured to climb over the plastic pipe 7, but this is not a limitation and the restriction on the plastic pipe 7 may be released by elasticity, or the temporary restricting portion 6 may be broken by a force applied in the axial direction and released. Also, the temporary restricting portion 6 has been described as being provided around the entire circumference, but this is not a limitation and the temporary restricting portion 6 may be a protrusion provided partially in the circumferential direction, or multiple temporary restricting portions 6 may be provided. Furthermore, the temporary restricting portion 6 has been described as being configured so that its position in the axial direction does not change, but this is not a limitation and the temporary restricting portion 6 may be configured to move toward the back in the axial direction in synchronization with the entry of the pipe end 71.

[0052] In addition, although the temporary restricting portion 6 has been described as being provided on the inner core 3, the present invention is not limited to this and may be provided on the inner circumferential surface 210 of the joint body 2, or may be configured as an elastic body extending from the rear surface 221 to the front side. Furthermore, although the position where it is temporarily restricted has been described as being on the rear side of the fastening member 5, the present invention is not limited to this and may be configured so as to be restricted on the front side of the fastening member 5.

[0053] Furthermore, although the fastening member 5 has been described as being annular, it is not limited to this configuration, and a non-annular fastening member 5 such as a C-shape may also be used.

[0054] Furthermore, although the fitting connection portion 23 has been described as having a male thread portion 231 formed therein, it may also have a female thread formed therein, or may be connectable to other pipe fittings 1 by a method other than threading, such as welding.

[0055] Furthermore, although the description has been given of the inner core outer peripheral surface 30 having two protrusions 310, this is not limiting, and the outer peripheral surface may have no protrusions 310, one or three or more protrusions 310, or a bamboo-shoot-shaped outer peripheral surface having multiple steps. Furthermore, the tapered outer surface 31 is not limited to a tapered shape, and may be configured to extend parallel to the axis, for example.

[0056] Furthermore, the straight outer surface 32, which is the outer surface of the straight portion 3B of the inner core 3 that temporarily forms the rear side of the restricting portion 6, has been described as having a substantially uniform diameter from the front side to the rear side, but is not limited to this configuration and may be configured to decrease or increase in diameter from the front side to the rear side. Note that even if the straight outer surface 32 is configured to decrease in diameter from the front side to the rear side, the straight outer surface 32 does not hinder the entry of the plastic pipe 7, so that the plastic pipe 7 that once enters beyond the restricting portion 6 is less likely to encounter resistance when entering the rear side, and an increase in the torque required to tighten the nut 4 can be suppressed.

[0057] Next, as a second embodiment of the present invention, a pipe fitting 1 as shown in Figures 4 and 5 will be described. Here, configurations that differ from those of the first embodiment shown in Figures 1 to 3 will be described, and common configurations will be assigned the same reference numerals and will not be described again.

[0058] In the pipe fitting 1 according to the second embodiment, the inner core 3 and the fitting body 2 are separate bodies. That is, in the pipe fitting 1 according to the second embodiment, the inner core 3 as shown in Fig. 4 is attached to the fitting body 2 as shown in Fig. 5 for use.

[0059] 4, the inner core 3 includes a cylindrical inner core body 35 that can be fitted into the resin tube 7, and a rear surface abutment portion 36 that is connected to the rear side of the inner core body 35. The inner core body 35 is also provided with a restricting portion 6.

[0060] The inner core body 35 includes a core body 3A having a tapered outer surface 31 that increases in diameter from the front side to the back side, a temporary restriction portion 6 that continues to the back side of the core body 3A, and a straight portion 3B that continues to the back side of the temporary restriction portion 6. The core body 3A has a tapered shape with a diameter that decreases toward the front side, and is configured so that the outer diameter is smaller than the inner diameter of the resin tube 7. The core body 3A also has a tapered outer surface 31. The tapered outer surface 31 further includes protrusions 310 that protrude radially outward in the circumferential direction. The configuration of the protrusions 310 is the same as in the first embodiment.

[0061] The straight portion 3B is an insertion guide portion that is connected to the rear side of the restricting portion 6 and that guides the insertion of the plastic pipe 7 that has been allowed to be inserted once beyond the restriction of the restricting portion 6. Specifically, the straight portion 3B has a straight outer surface 32 that is parallel to the axial direction and that is connected to the rear side from a restricting surface 6A (described later) of the restricting portion 6. This straight outer surface 32 has a substantially constant outer diameter from the front side to the rear side, and in this second embodiment, is connected to a rear surface abutment portion 36.

[0062] The rear surface abutment portion 36 is provided on the rear side of the inner core 3 and is configured to be able to abut against the rear surface 221. In the second embodiment, the rear surface abutment portion 36 is provided so as to protrude radially outward from the inner core body 35.

[0063] As shown in Figure 5, in this second embodiment, the additional insertion area 12 is a space defined by the outer peripheral surface of the inner core 3 and the front side surface of the rear surface abutment portion 36, and the rear surface 221 and inner peripheral surface 210 of the joint body 2.

[0064] The temporary restricting portion 6 is provided so as to come into contact with the pipe end 71 of the resin pipe 7 and temporarily restrict insertion of the resin pipe 7 toward the inner side in the axial direction. Specifically, the temporary restricting portion 6 is continuous with the inner side of the core body 3A, and is a stepped portion formed radially outward relative to the tapered outer surface 31, and includes a restricting surface 6A that expands radially outward from the tapered outer surface 31. The restricting surface 6A is provided around the outer peripheral surface of the inner core body 35.

[0065] The restricting surface 6A is configured to contact the pipe end 71, specifically the inner diameter edge portion 71A, of the resin pipe 7, thereby temporarily restricting the insertion of the resin pipe 7. The specific configuration of the restricting surface 6A is the same as that of the restricting surface 6A in the first embodiment.

[0066] The temporary restricting portion 6 is provided so as to be located further back in the axial direction than the fastening member 5 when the rear surface abutting portion 36 is brought into contact with the rear surface 221. Specifically, the temporary restricting portion 6 is provided further back than the rear end of the fastening member 5 when the rear surface abutting portion 36 is brought into contact with the rear surface 221. In addition, the temporary restricting portion 6 is provided at a position spaced apart from the rear surface 221 by a distance greater than the distance that the resin pipe 7 moves in the axial direction due to the tightening of the nut 4 when the rear surface abutting portion 36 is brought into contact with the rear surface 221.

[0067] The inner core 3 is fitted onto the resin pipe 7 up to the restricting portion 6 after the nut 4 and the tightening member 5 are fitted onto the outside of the resin pipe 7. Then, the resin pipe 7 with the inner core 3 fitted onto it is inserted into the joint body 2. When inserted into the joint body 2, the inner core 3 is arranged so that the inner core body 35 extends from the rear wall 22 towards the front side via the rear surface abutment portion 36.

[0068] After the plastic pipe 7 is inserted into the fitting body 2, as in the first embodiment, the nut 4 is threaded onto the fitting body 2, whereby the clamping member 5 clamps the plastic pipe 7, completing the attachment of the plastic pipe 7 to the pipe fitting 1. At this time, as the plastic pipe 7 is fixed to the pipe fitting 1, the inner core 3 fitted inside the plastic pipe 7 is also fixed to the fitting body 2. Specifically, when the nut is tightened, the clamping member 5 receives a force toward the rear in the axial direction, and the plastic pipe 7 clamped by the clamping member 5 also receives a force toward the rear in the axial direction. This force toward the rear in the axial direction causes the plastic pipe 7 to once pass over the restricting portion 6 and be allowed to advance further, and the pipe end 71 temporarily moves beyond the restricting portion 6 to the rear side. Furthermore, the portion of the plastic pipe 7 that once passed over the restricting portion 6 and advanced to the rear side (expanded portion 72) is once expanded in diameter by the restricting portion 6. That is, when the inner diameter edge 71A of the plastic pipe 7 receives a force toward the rear, it moves along the restricting surface 6A, thereby expanding the diameter of the inner diameter edge 71A. Next, the portion of the plastic pipe 7 on the front side of the inner diameter edge 71A also moves along the outer diameter side due to the restricting surface 6A, thereby expanding the diameter. Furthermore, once the pipe end 71 (inner diameter edge 71A) passes through the restricting portion 6, it is guided by the straight outer surface 32 that continues from the restricting surface 6A to the rear side, and smoothly advances to the rear side. Then, when the tightening is completed, the pipe end 71 does not reach the rear surface 221 and the front side surface of the rear surface abutting portion 36, and a gap 13 remains between the pipe end 71 and the rear surface 221 and the front side surface of the rear surface abutting portion 36.

[0069] Furthermore, when fastening is complete, the pipe end 71 is positioned at a position with a gap 13 between it and the rear face 221 and the rear face abutment portion 36. That is, the extension distance of the resin pipe 7 is once shorter than the distance from the restricting portion 6 to the rear face abutment portion 36.

[0070] With an inner core 3 configured in this manner, even if the inner core 3 is first attached to the resin pipe 7 and then the resin pipe 7 is inserted into the fitting body 2, the resin pipe 7 can be temporarily regulated, thereby suppressing an increase in the tightening torque of the nut 4.

[0071] Furthermore, since the inner core 3 is separate from the joint body 2, the inner core 3 can be attached to the pipe end portion in advance, and the plastic pipe 7 can be inserted into the joint body 2 after confirming that the pipe end 71 has once abutted against the regulating portion 6, so that the plastic pipe 7 can be reliably regulated once.

[0072] Furthermore, since the regulating portion 6 is located further forward than the rear surface abutment portion 36 that abuts against the rear surface 221 by at least the distance that the plastic pipe 7 advances when tightened, there is a gap 13 between the pipe end 71 and the member abutting against the rear surface 221 until tightening is complete, and therefore the tightening torque of the nut 4 can be prevented from increasing due to the abutment between the pipe end 71 and the rear member.

[0073] Furthermore, since the restricting portion 6 is configured to be able to expand the diameter of the plastic pipe 7, by tightening the nut 4, the plastic pipe 7 can be expanded in diameter and securely attached to the pipe fitting 1, eliminating the need to hammer the inner core 3 into the plastic pipe 7 with a hammer or the like.

[0074] In the second embodiment, the inner core 3 is described as having a rear surface abutment portion 36 that protrudes radially outward from the inner core body 35. However, this configuration is not limited to this. The inner core body 35 may be configured not to have a rear surface abutment portion 36, and the rear end portion of the inner core body 35 may abut against the rear surface 221, or the rear surface abutment portion 36 may extend radially inward from the inner core body 35.

[0075] In addition, although it has been explained that the inner core 3, nut 4, and fastening member 5 are attached to the plastic pipe 7 beforehand and then inserted into the joint body 2, the inner core 3 may be installed in the joint body 2 beforehand, and then the plastic pipe 7 may be inserted into the joint body 2 with the inner core 3 installed.

[0076] Furthermore, the core body 3A may be configured to have a tapered outer diameter that becomes larger than the outer diameter of the resin pipe 7 from the middle of the taper. In this configuration, the inner core 3 is fitted into the resin pipe 7 by hammering the inner core 3 into the resin pipe 7 with a hammer or the like until the pipe end 71 of the resin pipe 7 abuts against the restricting portion 6. In this configuration, the diameter of the resin pipe 7 is expanded by the taper of the core body 3A when the inner core 3 is driven in, and is further expanded by the restricting portion 6 once the nut is tightened. Therefore, the diameter of the resin pipe 7 can be expanded by the restricting portion 6 to an extent greater than the diameter expansion caused by hammering, and the amount of expansion caused by hammering can be reduced. This reduces the load required to drive the inner core 3 with a hammer or the like.

[0077] Next, a pipe fitting 1 according to a third embodiment of the present invention will be described with reference to Figures 6 and 7. Configurations that differ from those of the first embodiment shown in Figures 1 to 3 will be described, and common configurations will be assigned the same reference numerals and will not be described again.

[0078] In the pipe joint 1 according to the third embodiment, the restricting portion 6 is provided on the joint body 2 so as to come into contact with the outer periphery of the pipe end 71 of the resin pipe 7 .

[0079] In the third embodiment, the outer wall 21 of the joint body 2 constitutes the front end of the joint body 2 and includes a front outer wall 21A having a male thread portion 213 formed on its outer periphery, and a rear outer wall 21B connected to the rear wall 22, and a temporary restricting portion 6 is provided between the front outer wall 21A and the rear outer wall 21B. Specifically, the temporary restricting portion 6, which is a step portion, is connected to the rear side of the front outer wall 21A, and the rear outer wall 21B is connected to the rear side of the temporary restricting portion 6. The front outer wall 21A is also formed in a tapered shape such that the inner diameter increases toward the front and decreases toward the rear.

[0080] The inner peripheral surface of the front outer wall 21A is a fastening member abutment surface 211 against which the rear side of the fastening member can abut. Specifically, the fastening member abutment surface 211 constitutes the inner peripheral surface 210 from the front side to the middle, and has a tapered shape whose diameter decreases from the front side to the rear side. Furthermore, the fastening member abutment surface 211 temporarily connects with the front side of the restriction surface 6A of the restriction portion 6 at the smallest diameter portion.

[0081] The inner circumferential surface of the rear outer wall 21B is a rear inner circumferential surface 212 that is connected to the rear surface 221, and in this third embodiment, the rear inner circumferential surface 212 is a straight inner surface that extends parallel to the axis. Furthermore, the rear inner circumferential surface 212 is an insertion guide that guides the insertion of the resin pipe 7 that has once exceeded the restriction of the restricting portion 6 and is allowed to be inserted. Specifically, the rear inner circumferential surface 212 is a straight inner surface that is parallel to the axial direction and continues from the restricting surface 6A of the restricting portion 6 to the rear side. Furthermore, the rear inner circumferential surface 212 has a substantially constant inner diameter from the front side to the rear side, and the rear side is connected to the rear surface 221.

[0082] The temporary restricting portion 6 is a stepped portion that continues to the back side of the front outer wall 21A and is formed with a step that extends radially inward relative to the fastening member abutment surface 211, and is provided with a restricting surface 6A that narrows radially inward from the fastening member abutment surface 211. The restricting surface 6A is configured to abut against the outer diameter edge portion 71B of the plastic pipe 7, thereby temporarily restricting the insertion of the plastic pipe 7, and in this third embodiment, is a tapered surface that slopes radially inward from the front side to the back side.

[0083] The step of the temporary restricting portion 6 restricts the insertion of the plastic pipe 7 manually inserted by the operator, and when the nut 4 is tightened, the outer diameter of the plastic pipe 7 is reduced by the force toward the rear, allowing the plastic pipe 7 to overcome the step and enter further. That is, the minimum diameter of the temporary restricting portion 6 in this third embodiment is smaller than the outer diameter of the plastic pipe 7 by an amount that can temporarily restrict the plastic pipe 7 and that can be overcome by the force toward the rear due to tightening of the nut 4. Furthermore, the temporary restricting portion 6 is configured so that the diameter of the plastic pipe 7 that has passed through the temporary restricting portion 6 is reduced. That is, the temporary restricting portion 6 is configured with a hardness that can deform the plastic pipe 7.

[0084] The inner core outer peripheral surface 30 is provided with a tapered outer surface 31 and a straight outer surface 32. The straight outer surface 32 extends approximately parallel to the axis from a position before the position where the pipe end 71 of the resin pipe 7 temporarily contacts the restricting portion 6 in the axial direction until it connects to the rear surface 221. The tapered outer surface 31 forms the section from the front side of the inner core outer peripheral surface 30 to the straight outer surface 32.

[0085] The radial width of the additional insertion enabling region 12 is formed to be approximately the same as the wall thickness of the reduced diameter portion of the resin tube 7 when the resin tube 7 is reduced in diameter by fastening as described below.

[0086] When attaching a plastic pipe 7 to a pipe fitting 1 configured as described above, as shown in Fig. 6, the plastic pipe 7 is inserted until the pipe end 71 contacts the restricting portion 6, and the nut 4 is then screwed onto the fitting body 2. Then, as shown in Fig. 7, as the nut 4 is screwed onto the fitting body 2, the nut 4 presses the fastening member 5 radially inward, causing the fastening member 5 to contract in diameter. This tightens the plastic pipe 7 onto which the fastening member 5 is fitted, and the plastic pipe 7 is deformed so that the inner surface of the plastic pipe 7 and the outer peripheral surface of the inner core 3 come into close contact with each other.

[0087] Furthermore, at this time, the plastic pipe 7 receives a force acting toward the rear in the axial direction due to the tightening of the nut 4 via the tightening member 5. Therefore, the plastic pipe 7 passes over the restricting portion 6 and advances further toward the rear. Specifically, the pipe end 71 moves along the inclination of the restricting portion 6, and the plastic pipe 7 advances toward the rear while its diameter is reduced, and then passes over the restricting portion 6. Once the plastic pipe 7 has passed over the restricting portion 6, it advances toward the rear of the additional insertion possible region 12. Once the pipe end 71 (outer diameter edge portion 71B) has passed over the restricting portion 6, it is guided by the rear inner circumferential surface 212, which is a straight inner surface continuing from the restricting surface 6A toward the rear, and advances smoothly to the rear. Then, when tightening is completed, a gap 13 is formed between the pipe end 71 and the rear surface 221.

[0088] According to the pipe joint 1 having such a configuration, the restricting portion 6 is temporarily provided on the joint body 2, so that simply inserting the resin pipe 7 into the joint body 2 can reliably temporarily restrict it.

[0089] Furthermore, the inner core outer surface 30 has a straight outer surface 32 that extends parallel to the axis from the front side of the regulating portion 6 to the rear surface 221, so that the pipe end 71 that moves radially inward by the regulating portion 6 can be prevented from engaging with the tapered portion of the inner core outer surface 30, and an increase in the tightening torque of the nut 4 can be suppressed.

[0090] Furthermore, since the width of the additional insertion area 12 is formed to be approximately the same as the thickness of the resin pipe 7 once its diameter has been reduced by the restricting portion 6, resistance can be reduced when the reduced diameter resin pipe 7 enters the inner side of the additional insertion area 12, thereby preventing an increase in the tightening torque of the nut 4.

[0091] In the third embodiment, the temporary regulating portion 6 is described as being provided as a step portion between the fastening member abutment surface 211 and the rear inner circumferential surface 212. However, the present invention is not limited to this configuration, and the temporary regulating portion 6 may be provided, for example, with a regulating surface 6A that is the same tapered surface as the fastening member abutment surface 211.

[0092] Next, a pipe fitting 1 according to a fourth embodiment of the present invention will be described with reference to Figures 8 and 9. Configurations that differ from those of the first embodiment shown in Figures 1 to 3 will be described, and common configurations will be assigned the same reference numerals and descriptions thereof will be omitted.

[0093] 8, the pipe fitting 1 according to the fourth embodiment is provided with a temporary restricting portion 6 on a fastening member 5. Specifically, the temporary restricting portion 6 is provided on the rear side of the fastening member 5.

[0094] In the fourth embodiment, the temporary restricting portion 6 is an annular member provided on the fastening member 5. Specifically, the temporary restricting portion 6 is claw-shaped and extends rearward from the rear end of the fastening member 5. In the fourth embodiment, the temporary restricting portion 6 includes an extending portion 61 whose front side is connected to the fastening member 5 and a locking portion 62 extending radially inward from the rear side of the extending portion 61. The extending portion 61 also has a thin portion formed therein as a cutting means, and includes a connecting portion 611 whose front side is connected to the fastening member 5 and a connecting portion 612 extending rearward from the connecting portion 611. Specifically, the connecting portion 611 is configured to cut and separate the temporary restricting portion 6 from the fastening member 5 when the nut 4 is tightened to release the restriction by the temporary restricting portion 6, and is configured to have a thickness that decreases as it approaches the fastening member 5. The engaging portion 62 is configured so that the tip portion 621 has a diameter smaller than the outer diameter of the resin pipe 7. Therefore, the pipe end 71 can come into contact with the engaging portion 62.

[0095] When attaching a plastic pipe 7 to the pipe fitting 1 according to the fourth embodiment, as shown in Fig. 8, the plastic pipe 7 is inserted until the pipe end 71 comes into contact with the locking portion 62 of the restricting portion 6, and the nut 4 is then screwed onto the fitting body 2. Then, as shown in Fig. 9, as the nut 4 is screwed, the nut 4 presses the fastening member 5 radially inward, causing the fastening member 5 to contract in diameter, and the plastic pipe 7 onto which the fastening member 5 is fitted is tightened, and the plastic pipe 7 is deformed so that the inner surface of the plastic pipe 7 and the outer peripheral surface of the inner core 3 come into close contact with each other.

[0096] Here, the plastic pipe 7 is clamped by the clamping member 5 and receives a force toward the rear in the axial direction, so it attempts to advance further in the axial direction. Meanwhile, the rear side of the clamping member 5 is in contact with the clamping member contact surface 211, preventing it from advancing further inward. Meanwhile, the front portion of the clamping member 5 deforms radially inward and toward the rear, pushing the plastic pipe 7 toward the rear. As a result, a force acts on the plastic pipe 7 to push the locking portion 62 of the restricting portion 6 toward the rear. This force temporarily releases the connection between the clamping member 5 and the restricting portion 6, and as shown in FIG. 9, the restricting portion 6 is temporarily cut off from the clamping member 5 and falls off. This allows the plastic pipe 7 to advance further inward.

[0097] According to the pipe fitting 1 configured as described above, the restricting portion 6 is temporarily provided on the fastening member 5, which is a member that is fitted onto the outside of the plastic pipe 7 to fasten it, so that the insertion of the plastic pipe 7 can be reliably restricted temporarily.

[0098] In addition, since the restricting portion 6 is provided so as to extend from the fastening member 5 toward the rear side, it can be reliably restricted at a position further rear than the fastening member 5, and therefore the fastening member 5 can reliably clamp the resin pipe 7.

[0099] Furthermore, since a thin portion is formed in the restricting portion 6 as a cutting means, the force required to remove the restricting portion 6 is reduced, and an increase in the tightening torque of the nut 4 can be suppressed.

[0100] In the fourth embodiment, a case has been described in which a thin portion is formed as a cutting means for the temporary restricting portion 6, but the present invention is not limited to this configuration and may be made easier to cut by, for example, perforations, half cuts, etc. Also, the temporary restricting portion 6 has been described as including the extension portion 61 extending from the fastening member 5 to the rear side and the locking portion 62, but the present invention is not limited to this configuration and may be configured to include only the locking portion 62 extending radially inward from the fastening member 5.

[0101] Furthermore, while the restricting portion 6 has been described as being configured to temporarily detach from the fastening member 5 by a cutting means, the present invention is not limited to this configuration and may be configured to allow the plastic pipe 7 to enter due to the force acting toward the rear in the axial direction when the nut 4 is tightened. For example, the restricting portion 62 may be configured to release the lock by rotating (deflecting) radially outward around the connection portion with the fastening member 5, or the extending portion 61 may be configured to be extendable and contractible so that the force acting toward the rear causes the extending portion 61 to extend along with the entry of the plastic pipe 7, thereby allowing the entry of the plastic pipe 7. Furthermore, the extending portion 61 may be configured to deform so as to extend in the axial direction due to the force that moves the plastic pipe 7 toward the rear, or the restricting portion 6 may be configured to temporarily enter the rear together with the entry of the plastic pipe 7.

[0102] Next, a pipe fitting 1 according to a fifth embodiment of the present invention will be described with reference to Figures 10 and 11. Configurations that differ from those of the first embodiment shown in Figures 1 to 3 will be described, and common configurations will be assigned the same reference numerals and description thereof will be omitted.

[0103] As shown in FIG. 10, the pipe fitting 1 according to the fifth embodiment is provided with a restriction portion 6 extending from the rear surface 221 toward the front side.

[0104] The temporary restriction portion 6 in the fifth embodiment is an elastic body provided from the rear surface 221 toward the front side. Specifically, the temporary restriction portion 6 is an elastic body that can be compressed in the axial direction from the front side of the rear surface 221 and restored, and is a spring in the fifth embodiment.

[0105] The temporary restriction portion 6 includes an elastic body that is compressible and resilient in the axial direction from the front side of the rear surface 221. Specifically, two springs are provided on the rear wall 22, spaced approximately 180 degrees apart in the circumferential direction. The temporary restriction portion 6 is also provided so as to be compressible from the front side of the rear surface 221 toward the rear side. This elastic spring is configured to rebound toward the front side in the axial direction when the plastic pipe 7 is inserted, thereby temporarily restricting the insertion of the plastic pipe 7. Furthermore, when a force toward the rear side in the axial direction is applied by tightening the nut 4, the spring is compressed toward the rear side in the axial direction, thereby allowing the plastic pipe 7 to enter the rear side.

[0106] When attaching a plastic pipe 7 to the pipe fitting 1 according to the fifth embodiment, as shown in Fig. 10, the plastic pipe 7 is inserted until the pipe end 71 contacts the restricting portion 6, and the nut 4 is screwed onto the fitting body 2. Then, as shown in Fig. 11, as the nut 4 is screwed, the nut 4 presses the fastening member 5 radially inward, causing the fastening member 5 to contract in diameter, and the plastic pipe 7 onto which the fastening member 5 is fitted is tightened, and the plastic pipe 7 is deformed so that the inner surface of the plastic pipe 7 and the outer peripheral surface 30 of the inner core are in close contact with each other.

[0107] Here, the resin pipe 7 is subjected to a force toward the rear in the axial direction, so the restricting portion 6 is compressed and deformed so as to sink toward the rear. That is, the spring length in the temporary restricting state as shown in Figure 10 is shortened to the spring length in the compressed state as shown in Figure 11. The resin pipe 7 can advance toward the rear by this shortened distance.

[0108] With the pipe fitting 1 having such a configuration, the force acting axially toward the rear when the nut 4 is tightened compresses the elastic body provided on the rear wall 22, allowing the plastic pipe 7 to enter the compressed distance, and the force caused by tightening the nut 4 can be absorbed by the movement of the plastic pipe 7, thereby suppressing an increase in the tightening torque of the nut 4.

[0109] Furthermore, since the restricting portion 6 is made of an elastic body that can be compressed and restored in the axial direction, even if a strong force is applied to the rear side in the axial direction when inserting the plastic pipe 7, the elastic body can restore its original shape before tightening the nut 4. Therefore, the force applied to the rear side in the axial direction by tightening the nut 4 can be reliably absorbed by the movement of the plastic pipe 7, and an increase in the tightening torque of the nut 4 can be reliably suppressed.

[0110] In the fifth embodiment, the elastic body is described as a spring, but the elastic body is not limited to this, and various elastic bodies that can be compressed and restored, such as rubber or sponge, can be used.

[0111] Furthermore, the elastic body that serves as the restricting portion 6 is not limited to being provided in advance on the rear wall 22, but may be attached to the pipe end 71 or may be inserted separately into the joint body 2.

[0112] Furthermore, the spring is not limited to being arranged in a plurality around the inner core 3, but may be a coil spring wound around the inner core 3.

[0113] The present embodiment will be summarized below.

[0114] A pipe joint according to the present invention comprises a cylindrical joint body having an external thread formed on its outer peripheral surface, into which a plastic pipe can be inserted from the front side to the rear side in the axial direction, a cylindrical inner core fitted to the inside of an end portion of the plastic pipe, a nut that can be screwed onto the external thread of the joint body, a fastening member that can be fitted to the outside of the plastic pipe, and a temporary restricting portion, wherein the joint body has an inner peripheral surface that faces the outer peripheral surface of the inserted plastic pipe, and a rear surface that extends radially inward from the rear end of the inner peripheral surface, and the inner core is provided so as to extend from the rear surface towards the front side, and a contact between the inner peripheral surface, the rear surface and the inner core An insertion space into which the plastic pipe can be inserted is formed in a space surrounded by the outer peripheral surface, the nut has a fastening member pressing portion that is arranged so as to be able to press the fastening member inward radially by screwing it onto the fitting body, the fastening member is configured to reduce in diameter so as to fasten the plastic pipe by the pressure of the fastening member pressing portion, and the temporary restricting portion is configured to contact the pipe end of the plastic pipe in an axial midpoint of the insertion space to temporarily restrict the insertion of the plastic pipe toward the rear in the axial direction, and to allow the insertion of the plastic pipe toward the rear in the axial direction by the force toward the rear in the axial direction caused by the tightening of the nut.

[0115] With this configuration, the plastic pipe is inserted into the insertion space until the pipe end contacts the restricting portion and insertion is restricted. When the nut is threaded onto the fitting body, the clamping member pressing portion presses the clamping member radially inward, causing the clamping member to contract and clamp the plastic pipe. Further tightening of the nut applies a force to the plastic pipe in the axial direction caused by the tightening of the nut to the rear through the clamping member that clamps the plastic pipe. The restricting portion then allows the plastic pipe to be inserted further inward, and the plastic pipe is inserted further inward. Therefore, the axial force applied to the plastic pipe by tightening the nut to the rear can be absorbed by the plastic pipe moving further inward, thereby suppressing an increase in the torque required to tighten the nut.

[0116] The temporary restriction portion may be provided at a position between the fastening member and the rear surface in the axial direction of the insertion space.

[0117] With this configuration, the plastic pipe is inserted as far as it will go beyond the clamping member, and then the insertion is temporarily restricted, so that the end of the pipe can be positioned further back than the clamping member. The clamping member, which is pressed axially by the nut to reduce its diameter, can reliably clamp the plastic pipe, and the plastic pipe can be reliably attached to the pipe fitting.

[0118] The temporary restriction portion may be provided on the joint body.

[0119] According to this configuration, since the restricting portion is already provided inside the joint body, the plastic pipe can be restricted once inserted into the joint body.

[0120] The temporary restricting portion may be provided on the fastening member.

[0121] According to this configuration, the restricting portion is provided on the fastening member, which is a member fitted onto the outside of the resin pipe to fasten it, so that the insertion of the resin pipe can be reliably restricted.

[0122] The temporary restricting portion may be provided on the inner core.

[0123] According to this configuration, the restricting portion is temporarily provided on the inner core, which is a member fitted inside the resin pipe, so that the insertion of the resin pipe can be reliably temporarily restricted.

[0124] The inner core according to the present invention comprises a cylindrical joint body having an external thread formed on its outer peripheral surface, into which a plastic pipe can be inserted from the front side to the rear side in the axial direction; a nut that can be threaded onto the external thread of the joint body; and a fastening member that can be fitted onto the plastic pipe. The joint body comprises an inner peripheral surface that faces the outer peripheral surface of the inserted plastic pipe, and a rear surface that extends radially inward from the rear end of the inner peripheral surface and forms, together with the inner peripheral surface, an insertion space into which the plastic pipe is inserted. The nut comprises a fastening member pressing portion that can press the fastening member radially inward when threaded onto the joint body. The clamping member is an inner core used in a pipe fitting configured to reduce the diameter so as to clamp the plastic pipe by pressing the clamping member pressing portion, and is formed in a cylindrical shape to be fitted into the pipe end portion of the plastic pipe, and is configured to be arranged in the insertion space so as to extend from the back side to the front side, and further includes a temporary restricting portion that contacts the pipe end of the plastic pipe in the axial midpoint of the insertion space to temporarily restrict the insertion of the plastic pipe toward the back side in the axial direction, and allows the plastic pipe to be inserted toward the back side in the axial direction by the force toward the back side in the axial direction caused by tightening the nut.

[0125] According to a pipe joint using an inner core of this configuration, the pipe end comes into contact with the restricting portion, and the inner core is fitted into the resin pipe until the insertion is restricted, and the nut is screwed onto the joint body. When the nut is tightened further, the clamping member pressing portion presses the clamping member radially inward, causing the clamping member to contract and clamp the plastic pipe. If the nut is tightened further, the force acting in the axial direction toward the rear of the plastic pipe due to the tightening of the nut is applied to the plastic pipe via the clamping member that tightens the plastic pipe. The restricting portion temporarily allows the plastic pipe to be inserted further inward, and the plastic pipe is inserted further inward. Therefore, the force acting in the axial direction toward the rear of the plastic pipe due to the tightening of the nut can be absorbed by the plastic pipe moving further inward, thereby suppressing an increase in the torque required to tighten the nut. [Explanation of symbols]

[0126] 1...pipe fitting, 11...insertion space, 12...additional insertion possible area, 13...gap, 2...fitting body, 20...resin pipe insertion portion, 21...outer wall, 21A...front outer wall, 21B...rear outer wall, 210...inner circumferential surface, 211...fastening member abutment surface, 212...rear inner circumferential surface, 213...male thread portion, 214...nut receiving portion, 22...rear wall, 221...rear surface, 23...fitting connection portion, 231...male thread portion, 24...fitting operating portion, 3...inner core, 3A...core body, 3B...straight portion, 30...inner core outer circumferential surface, 31...tapered outer surface, 310...projection , 311...front side protrusion, 312...middle protrusion, 313...outer surface between protrusions, 32...straight outer surface, 35...inner core body, 36...rear surface abutment portion, 4...nut, 41...female thread portion, 42...fastening member pressing portion, 43...joint abutment portion, 44...nut operating portion, 5...fastening member, 51...inner peripheral surface, 511...curved portion, 52...slit, 6...temporary restricting portion, 6A...restricting surface, 61...extending portion, 611...connecting portion, 612...connecting portion, 62...engaging portion, 7...plastic pipe, 71...pipe end, 71A...inner diameter edge portion, 71B...outer diameter edge portion, 72...expanded diameter portion

Claims

1. The joint body includes a cylindrical joint body having an external thread formed on its outer peripheral surface and into which a plastic pipe can be inserted from the front side to the back side in the axial direction, a cylindrical inner core fitted to the end portion of the plastic pipe, a nut that can be threaded onto the external thread of the joint body, a tightening member that can be fitted onto the outside of the plastic pipe, and a temporary restricting portion, The joint body includes an inner circumferential surface facing an outer circumferential surface of the inserted resin pipe, and a rear surface extending radially inward from a rear end of the inner circumferential surface, The inner core is provided so as to extend from the rear surface toward the front side, an insertion space into which the resin tube can be inserted is formed in a space surrounded by the inner peripheral surface, the rear surface, and the outer peripheral surface of the inner core; the nut includes a fastening member pressing portion that is capable of pressing the fastening member in a radially inward direction by being threadedly engaged with the joint body, The clamping member is configured to reduce its diameter so as to clamp the resin pipe by being pressed by the clamping member pressing portion, The inner core is formed in a cylindrical shape to be fitted into the end portion of the resin pipe, and includes a core body disposed in the insertion space so as to extend from the rear side toward the front side, a temporary restriction portion continuing from the core body to the rear side, and an insertion guide portion extending from the temporary restriction portion to the rear side, The temporary restricting portion is an inclined surface that is more inclined in the axial direction of the insertion space than the core body and the insertion guide portion, and contacts the pipe end of the plastic pipe midway in the axial direction of the insertion space to temporarily restrict the insertion of the plastic pipe toward the rear in the axial direction, and allows the plastic pipe to be inserted toward the rear in the axial direction by the force toward the rear in the axial direction caused by tightening the nut, so that a gap is formed between the pipe end and the rear surface when the nut is completely screwed onto the fitting body.

2. The joint body is cylindrical and has an external thread formed on its outer peripheral surface, into which a plastic pipe can be inserted from the front side to the back side in the axial direction; a nut that can be threaded onto the external thread of the joint body; and a fastening member that can be fitted onto the outside of the plastic pipe. the fitting body includes an inner circumferential surface facing an outer circumferential surface of the inserted plastic pipe, and a rear surface extending radially inward from a rear end of the inner circumferential surface and forming, together with the inner circumferential surface, an insertion space into which the plastic pipe is inserted, the nut includes a fastening member pressing portion that is capable of pressing the fastening member in a radially inward direction by being threadedly engaged with the joint body, The fastening member is an inner core used in a pipe joint configured to reduce the diameter of the resin pipe so as to fasten the resin pipe by pressing the fastening member pressing portion, The end of the resin pipe is fitted into the cylindrical shape, and the end of the resin pipe is arranged in the insertion space so as to extend from the rear side to the front side. Moreover, the nut includes a core body formed in a cylindrical shape to be fitted into the pipe end portion of the plastic pipe and disposed in the insertion space so as to extend from the rear side toward the front side, a temporary restricting portion continuing from the core body to the rear side and contacting the pipe end of the plastic pipe in an axially intermediate portion of the insertion space to temporarily restrict insertion of the plastic pipe toward the rear side in the axial direction, and allowing insertion of the plastic pipe toward the rear side in the axial direction by a force toward the rear side in the axial direction due to tightening of the nut, an insertion guide portion extending toward the rear side from the temporary restricting portion, and a rear face abutting portion abutting against the rear face, The inner core is characterized in that the temporary regulating portion is composed of a step portion formed radially outward of the core body, having an inclined surface that is more inclined with respect to the axial direction of the insertion space than the core body and the insertion guide portion, and is configured so that a gap is formed between the pipe end and the rear surface abutment portion when the nut is completely screwed onto the fitting body.

3. The joint body is cylindrical and has an external thread formed on its outer peripheral surface, into which a plastic pipe can be inserted from the front side to the back side in the axial direction; a nut that can be threaded onto the external thread of the joint body; and a fastening member that can be fitted onto the outside of the plastic pipe. the fitting body includes an inner circumferential surface facing an outer circumferential surface of the inserted plastic pipe, and a rear surface extending radially inward from a rear end of the inner circumferential surface and forming, together with the inner circumferential surface, an insertion space into which the plastic pipe is inserted, the nut includes a fastening member pressing portion that is capable of pressing the fastening member in a radially inward direction by being threadedly engaged with the joint body, The fastening member is an inner core used in a pipe joint configured to reduce the diameter of the resin pipe so as to fasten the resin pipe by pressing the fastening member pressing portion, a core body formed in a cylindrical shape to be fitted into the end portion of the resin pipe and disposed in the insertion space so as to extend from the rear side toward the front side; a temporary restricting portion continuing from the core body to the rear side; and an insertion guide portion extending from the temporary restricting portion to the rear side, The temporary restricting portion is composed of a stepped portion formed radially outward of the core body, having a restricting surface extending radially outward from the outer peripheral surface of the core body, and is configured such that the restricting surface abuts against the pipe end of the plastic pipe inserted into the insertion space, thereby temporarily restricting insertion of the plastic pipe toward the inner axial direction, and allowing insertion of the plastic pipe toward the inner axial direction beyond the temporary restricting portion by the force toward the inner axial direction caused by tightening the nut, The inner core is characterized in that the restriction surface is an inclined surface that is more inclined with respect to the axial direction of the insertion space than the core body and the insertion guide portion.

4. The inner core according to claim 3 , wherein the insertion guide portion is a straight portion having a straight outer surface extending along the axial direction.

5. The inner core according to claim 3 or 4, wherein an outer diameter of the core body is smaller than an inner diameter of the resin tube.

6. A fitting body having a cylindrical shape and a male thread formed on its outer peripheral surface, into which a plastic pipe can be inserted from the front to the back in the axial direction, a cylindrical inner core fitted into the end portion of the plastic pipe, a nut that can be threaded onto the male thread of the fitting body, a tightening member that can be fitted onto the outside of the plastic pipe, and a temporary restricting portion; The joint body includes an inner circumferential surface facing an outer circumferential surface of the inserted resin pipe, and a rear surface extending radially inward from a rear end of the inner circumferential surface, The inner core is provided so as to extend from the rear surface toward the front side, an insertion space into which the resin tube can be inserted is formed in a space surrounded by the inner peripheral surface, the rear surface, and the outer peripheral surface of the inner core; the nut includes a fastening member pressing portion that is capable of pressing the fastening member in a radially inward direction by being threadedly engaged with the joint body, The clamping member is configured to reduce its diameter so as to clamp the resin pipe by being pressed by the clamping member pressing portion, The inner core is formed in a cylindrical shape to be fitted into the end portion of the resin pipe, and includes a core body disposed in the insertion space so as to extend from the rear side toward the front side, a temporary restriction portion continuing from the core body to the rear side, and an insertion guide portion extending from the temporary restriction portion to the rear side, The temporary restricting portion is composed of a stepped portion formed radially outward of the core body, having a restricting surface extending radially outward from the outer peripheral surface of the core body, and is configured such that the restricting surface abuts against the pipe end of the plastic pipe inserted into the insertion space, thereby temporarily restricting insertion of the plastic pipe toward the inner axial direction, and allowing insertion of the plastic pipe toward the inner axial direction beyond the temporary restricting portion by the force toward the inner axial direction caused by tightening the nut, A pipe joint, wherein the regulating surface is an inclined surface that is more inclined with respect to the axial direction of the insertion space than the core body and the insertion guide portion.

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