Pipe joint

Abstract

To provide a pipe joint which can be assembled easily and properly without needing a special facility and prevent leakage of a fluid when a nut member is fastened and a pressure of the fluid varies.SOLUTION: When a nut member 20, 70 coaxially fitted at a flat inner peripheral surface 23, 73 into a core fitting cylindrical part 11 of a core fitting 10, 60 is in a predetermined axial relative position relation with the core fitting 10, 60, a core fitting side outer peripheral groove 11v, 61V and a nut side inner peripheral groove 23v, 73v are matched to form a ring fitting hole V. An engagement ring 30, 80 is fitted in the ring fitting hole V to cause the nut member 20, 70 to be engaged with and attached to the core fitting 10, 60 while restrained from moving axially relative to the core fitting 10, 60 in a direction away from the core fitting and allowed to rotate relative to the core fitting. The core fitting side outer peripheral groove 11v, 61v has a groove depth deeper than that of the nut side inner peripheral groove 23v, 73v.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a pipe joint that connects a core fitting to a joint fitting via a nut member.

Background Art

[0002] The pipe joint according to the present invention has a structure in which a female screw of a nut member fitted to a core fitting connected to a pipe body is screwed and tightened to a male screw formed on a joint fitting cylindrical portion that forms an outflow inlet of the joint fitting, thereby connecting the joint fitting to the core fitting.

[0003] In this type of pipe joint, when fitting the nut member to the core fitting, it is necessary to restrict relative movement of the nut member in a direction away from the axial core fitting and lock it so as to be relatively rotatable and attach it. As such a pipe joint, there is an example using a clamping nut (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] The pipe joint disclosed in Patent Document 1 includes a joint body (corresponding to a core fitting) fixed to an end of a hose, and a clamping nut having a nut portion formed at one end of a cylindrical portion and a protrusion protruding inward on the inner peripheral side at the other end.

[0006] The clamping nut covers the cylindrical portion of the joint body having an outlet of the joint body coaxially with the nut portion outside the cylindrical portion of the joint body in the axial direction, and clamps the end portion of the cylindrical portion having the protrusion inward in the radial direction to plastically deform the cylindrical portion, so that the protrusion of the clamping nut is relatively rotatably accommodated in a concave groove formed on the outer peripheral surface of the cylindrical portion of the joint body. Thus, relative movement of the clamping nut in a direction away from the axial joint body is restricted, and it is locked so as to be relatively rotatable and attached to the joint body.

[0007] By screwing and tightening the clamping nut attached to the joint body onto the male thread formed on the cylindrical portion that serves as the fluid inlet / outlet of the joint fitting, the joint body and the joint fitting are pressed against each other and connected.

Summary of the Invention

Problems to be Solved by the Invention

[0008] In this way, by tightening the clamping nut, the cylindrical portion is plastically deformed so that the protruding portion is accommodated in the concave groove of the joint body, and by tightening the nut portion, the joint body and the joint fitting are pressed against each other and connected.

[0009] Since the pressure of the fluid flowing through the joint body and the joint fitting acts in a direction to separate the joint body and the joint fitting, the clamping nut together with the joint body receives a force in the direction of separating from the joint fitting. A force acts in the opening direction on the cylindrical portion of the clamping nut that has been plastically deformed in the closing direction. When high-pressure fluid flows frequently and the pressure fluctuation is repeated, stress will act repeatedly in the opening direction on the cylindrical portion of the clamping nut. Also, if the tightening of the clamping nut is excessive, the cylindrical portion will undergo reverse deformation from the plastic deformation, the pressure contact between the joint body and the joint fitting will become weak, gaps will occur, and there is a risk of fluid leakage.

[0010] Also, to attach the clamping nut to the joint body, the end portion of the cylindrical portion of the clamping nut with the protruding portion is tightened radially inward to plastically deform the cylindrical portion. However, if the deformation is insufficient, the engagement of the protruding portion may be insufficient and it may come off. Also, if the deformation is excessive, it will press against the bottom surface and side surface of the concave groove of the joint body, making it difficult to rotate the clamping nut. Therefore, it is difficult to tighten the clamping nut appropriately and accurately, and since it is necessary to tighten the end portion of the cylindrical portion of the clamping nut with the protruding portion evenly radially inward over the entire circumference, dedicated equipment for tightening is required.

[0011] Therefore, the inventor of the present invention considered a structure in which a locking ring is interposed between a core fitting and a nut member, and the nut member is locked to the core fitting so as to be relatively rotatable while restricting relative movement in a direction away from the core fitting in the axial direction, as a pipe joint that does not require dedicated equipment and can be easily and properly assembled.

[0012] That is, when the nut member coaxially fitted to the core fitting cylindrical portion forming the inlet and outlet of the core fitting is at a predetermined position in the axial direction, the core fitting side outer peripheral groove formed on the outer peripheral surface of the core fitting cylindrical portion and the nut side inner peripheral groove formed on the flat inner peripheral surface of the nut member coincide to form a common ring fitting hole. By fitting the locking ring into this ring fitting hole, the nut member is locked to the core fitting by the locking ring, and relative movement in a direction away from the core fitting in the axial direction is restricted and it is attached so as to be relatively rotatable.

[0013] By fitting the locking ring into the ring fitting hole commonly formed on the mating surface where the core fitting and the nut member are fitted, it can be assembled easily and appropriately. Then, the female thread of the nut member, whose relative movement in the direction away from the core fitting in the axial direction is restricted by the locking ring, is screwed onto the male thread formed on the joint fitting cylindrical portion forming the inlet and outlet, and the joint fitting is brought close to the core fitting and tightened, thereby enabling connection.

[0014] However, when the nut member was tightened with the torque required to connect the joint fitting to the core fitting, the core fitting side outer peripheral groove of the core fitting sometimes buckled and deformed due to the pressing of the locking ring. When the core fitting side outer peripheral groove buckles and deforms, the pressure contact between the joint body and the joint fitting becomes weak, gaps are generated, and there is a risk of fluid leakage.

[0015] As a result of intensive research, the inventor of the present invention obtained the following findings. In the initially considered pipe joint, the ring insertion holes formed in common on the mating surfaces where the core fitting and the nut member are fitted are in an equal position on both the core fitting and the nut member, that is, the depths of the outer peripheral groove on the core fitting side and the inner peripheral groove on the nut side are equal. Therefore, for the locking ring inserted into this ring insertion hole, the outer peripheral half thereof is fitted into the inner peripheral groove on the nut side, and the inner peripheral half thereof is fitted into the outer peripheral groove on the core fitting side.

[0016] When the female thread of the nut member is screwed onto the male thread formed on the joint fitting cylindrical portion forming the outflow and inflow ports and tightened with the required torque, a pressing force is applied in the axial direction in opposite directions to the outer peripheral half fitted in the inner peripheral groove on the nut side of the locking ring and the inner peripheral half fitted in the outer peripheral groove on the core fitting side. As a result, the locking ring is easily deformed along the mating surface between the core fitting cylindrical portion and the nut member. When the locking ring is deformed, a pressing force acts on the easily buckled opening edge of the outer peripheral groove on the core fitting side, which is considered to cause buckling deformation.

[0017] Also, for a pipe joint in which the ring insertion holes formed in common on the mating surfaces where the core fitting and the nut member are fitted are formed at a position biased toward the nut member side, when the female thread of the nut member is screwed onto the male thread of the joint fitting cylindrical portion and tightened with the required torque, the outer peripheral groove on the core fitting side of the core fitting may undergo buckling deformation.

[0018] Based on the above findings, the inventor of the present invention has found that by devising the way the locking ring contacts the outer peripheral groove on the core fitting side and the inner peripheral groove on the nut side, deformation of the core fitting can be avoided.

[0019] The present invention has been made in view of the above points, and its object is to provide a pipe joint that does not require dedicated equipment, can be easily and properly assembled, and can avoid deformation of the core fitting and prevent fluid leakage when the nut member is tightened and during fluid pressure fluctuations.

Means for Solving the Problems

[0020] To achieve the above object, the present invention A pipe joint in which a nut member having an internal thread and a flat inner peripheral surface formed on both axial sides is coaxially fitted with the flat inner peripheral surface with the internal thread on the outer side in the axial direction of the ferrule cylindrical portion forming the inlet and outlet of the ferrule connected to the pipe body, and the nut member is locked to be relatively rotatable and restricted from relative movement in the direction away from the ferrule in the axial direction with respect to the ferrule. In the pipe joint in which the female thread of the nut member is screwed and tightened with a male thread formed on a joint fitting cylindrical portion forming an inlet and outlet of the joint fitting, the joint fitting cylindrical portion is connected to the ferrule cylindrical portion via the nut member. An outer peripheral groove on the ferrule side is formed in an annular shape on the outer peripheral surface of the ferrule cylindrical portion. An inner peripheral groove on the nut side is formed in an annular shape on the flat inner peripheral surface of the nut member. When the nut member with the flat inner peripheral surface coaxially fitted to the ferrule cylindrical portion of the ferrule is in a predetermined relative positional relationship in the axial direction with respect to the ferrule, the outer peripheral groove on the ferrule side and the inner peripheral groove on the nut side coincide to form a ring insertion hole. By inserting a locking ring into the ring insertion hole, the nut member is locked to be relatively rotatable and restricted from relative movement in the direction away from the ferrule in the axial direction with respect to the ferrule. Provided is a pipe joint characterized in that the outer peripheral groove on the ferrule side is deeper in groove depth than the inner peripheral groove on the nut side.

[0021] According to this configuration, when the female thread of the nut member is screwed into the male thread formed on the joint fitting cylindrical portion and tightened with the required torque, a pressing force is applied in opposite directions in the axial direction to the outer peripheral side portion fitted in the inner peripheral groove on the nut side with a shallow groove depth of the locking ring and the inner peripheral side portion fitted in the outer peripheral groove on the ferrule side with a deep groove depth. Since the mating surface is biased toward the nut member side, it is considered that deformation such as buckling of the opening edge of the outer peripheral groove on the ferrule side hardly occurs, and deformation of the outer peripheral groove on the ferrule side of the ferrule is avoided. Therefore, it is possible to strongly maintain the press contact between the core fitting cylindrical portion and the joint fitting cylindrical portion without weakening it, without creating a gap, and without preventing fluid leakage.

[0022] Further, the flat inner peripheral surface of the nut member contacts the outer peripheral surface of the coaxial core fitting cylindrical portion, and the locking ring is fitted into the ring fitting hole formed by the alignment of the core fitting side outer peripheral groove and the nut side inner peripheral groove in a predetermined relative positional relationship in the axial direction. Since the nut member is locked so as to be relatively rotatable and restricted from relative movement in the direction away from the core fitting in the axial direction, it can be assembled easily and appropriately without requiring special dedicated equipment.

[0023] In a preferred embodiment of the present invention, When the female thread of the nut member is screwed into and tightened by the male thread of the joint fitting cylindrical portion, the end surface of the core fitting cylindrical portion and the end surface of the joint fitting cylindrical portion are pressed into contact and connected.

[0024] According to this configuration, when the nut member screws and tightens the female thread to the male thread of the joint fitting cylindrical portion, the end surface of the core fitting cylindrical portion and the end surface of the joint fitting cylindrical portion are pressed into contact and connected. Therefore, the inside of the connected core fitting cylindrical portion and joint fitting cylindrical portion flows smoothly.

[0025] In a preferred embodiment of the present invention, The end surfaces of the core fitting cylindrical portion and the joint fitting cylindrical portion that are in pressure contact with each other are conical surfaces having an inclination with respect to the axial direction.

[0026] According to this configuration, since the end surfaces of the core fitting cylindrical portion and the joint fitting cylindrical portion that are in pressure contact with each other are conical surfaces having an inclination with respect to the axial direction, one conical (end) surface bites into the inside of the other conical (end) surface and is pressed into contact with a large contact area. Therefore, a large static frictional force acts and the core fitting cylindrical portion and the joint fitting cylindrical portion are firmly connected. In combination with the fact that the ring fitting hole is formed so as to be biased toward the core fitting cylindrical portion side, the press contact between the core fitting cylindrical portion and the joint fitting cylindrical portion can be strongly maintained. Even if there is a pressure fluctuation in the fluid flowing inside the core fitting cylindrical portion and the joint fitting cylindrical portion, fluid leakage can be more reliably prevented.

[0027] In a preferred embodiment of the present invention, the locking ring is a ring having elasticity formed in a C-shaped arc, the nut member is formed with an annular reduced-diameter portion having an inner diameter equal to the outer diameter of the ferrule cylindrical portion by reducing the inner diameter at the end opposite to the female thread of the nut cylindrical body, and having a flat inner peripheral surface, a nut-side inner peripheral groove is formed at the opening edge portion on the female thread side of the flat inner peripheral surface of the annular reduced-diameter portion, When the nut member is in a predetermined relative positional relationship in the axial direction in which the outer peripheral groove on the ferrule side and the inner peripheral groove on the nut side coincide with respect to the ferrule, an annular recess formed between the female thread on the inner peripheral surface of the nut cylindrical body and the annular reduced-diameter portion forms a gap between the ferrule cylindrical portion inside the nut member.

[0028] According to this configuration, when the nut member is positioned with respect to the ferrule in a predetermined relative positional relationship in the axial direction in which the outer peripheral groove on the ferrule side and the inner peripheral groove on the nut side coincide, the gap formed between the ferrule cylindrical portion by the annular recess of the nut member communicates with the nut-side inner peripheral groove and the ferrule-side outer peripheral groove formed at the opening edge portion on the female thread side of the flat inner peripheral surface of the annular reduced-diameter portion. Therefore, while expanding the locking ring having elasticity formed in a C-shaped arc, it can be easily inserted into the ring insertion hole in which the nut-side inner peripheral groove and the ferrule-side outer peripheral groove coincide through the gap formed by the annular recess. The locking ring inserted into this ring insertion hole restricts the relative movement of the nut member with respect to the ferrule in the direction of separating from the ferrule in the axial direction and is locked so as to be relatively rotatable and attached. Therefore, assembly can be performed more simply and appropriately without the need for special dedicated equipment.

[0029] In a preferred embodiment of the present invention, a pin insertion hole extending in the tangential direction of the inner peripheral circle of the nut-side inner peripheral groove is formed to penetrate outward in the tangential direction from the nut-side inner peripheral groove in the nut member, A flexible pin is inserted into the pin insertion hole and further inserted into the ring insertion hole to form the locking ring.

[0030] According to this configuration, a flexible pin is inserted into the pin insertion hole, and further inserted into an arcuate ring insertion hole formed by the alignment of an outer peripheral groove on the core fitting side with a deeper groove depth and an inner peripheral groove on the nut side with a shallower groove depth to form a locking ring. As a result, the locking ring can be more easily inserted into the ring insertion hole. The nut member is locked to the core fitting by the locking ring inserted into this ring insertion hole in such a way that relative movement in the axial direction away from the core fitting is restricted and relative rotation is possible. Therefore, assembly can be performed more simply and appropriately without the need for special dedicated equipment.

Advantages of the Invention

[0031] In the present invention, when the female thread of the nut member is screwed onto the male thread formed on the cylindrical portion of the joint fitting and tightened with the required torque, a pressing force is applied in opposite axial directions to the outer peripheral portion fitted into the nut-side inner peripheral groove with a shallower groove depth of the locking ring and the inner peripheral portion fitted into the core fitting-side outer peripheral groove with a deeper groove depth. However, since the mating surface between the cylindrical portion of the core fitting and the nut member is biased toward the nut member side, there is no deformation of the locking ring along the mating surface, particularly no deformation that causes buckling of the opening edge of the core fitting-side outer peripheral groove. The pressure contact between the joint body and the joint fitting can be strongly maintained without creating a gap, preventing fluid leakage.

[0032] Also, since the locking ring is inserted into the ring insertion hole formed by the alignment of the core fitting-side outer peripheral groove and the nut-side inner peripheral groove, relative movement of the nut member in the axial direction away from the core fitting is restricted and it is locked and attached so as to be relatively rotatable. Therefore, assembly can be performed simply and appropriately without the need for special dedicated equipment.

Brief Description of the Drawings

[0033]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0034] Hereinafter, a first embodiment according to the present invention will be described with reference to FIGS. 1 to 6. FIG. 1 is a side view showing a partial cross-section of the pipe joint 1 according to the first embodiment, and FIG. 2 is an exploded side view showing a partial cross-section of the same pipe joint 1. The pipe joint 1 is composed of a combination of a core fitting 10 fixed to the end of a hose 18 which is a pipe body, a nut member 20, and a locking ring 30.

[0035] Referring to FIG. 2, the core fitting 10 has a cylindrical shape with a flow passage through which fluid flows inside. There is a hexagonal flange portion 12 with a hexagonal outer shape in the center. A core fitting cylindrical portion 11 forming an outflow inlet is axially projected on one side of the hexagonal flange portion 12. On the other side of the hexagonal flange portion 12, a cylindrical stepped portion 13 with an outer diameter reduced from that of the hexagonal flange portion 12 is formed. A small-diameter cylindrical portion 14 with an outer diameter further reduced from that of the cylindrical stepped portion 13 and having irregularities formed on its outer peripheral surface extends axially.

[0036] At the end of a flexible hose 18 with an inner diameter slightly smaller than the outer diameter of the small-diameter cylindrical portion 14 of the core fitting 10 and an outer diameter slightly larger than the outer diameter of the cylindrical stepped portion 13, the small-diameter cylindrical portion 14 of the core fitting 10 is inserted. A clamping fitting 19 forming a cylindrical shape is fitted onto the outer peripheral surface of the end of the hose 18 and the outer peripheral surface of the cylindrical stepped portion 13 of the core fitting 10, and by being clamped radially inward, the inner peripheral surface of the hose 18 bites into the irregularities on the outer peripheral surface of the small-diameter cylindrical portion 14, and the end of the hose 18 is firmly fixed to the core fitting 10.

[0037] The end face of the core fitting cylindrical portion 11 forming the outflow inlet of the core fitting 10 is a conical end face 11t that is inclined with respect to the axial direction and has an outer diameter that becomes smaller towards the tip. On the cylindrical outer peripheral surface 11s between the conical end face 11t of the core fitting cylindrical portion 11 and the hexagonal flange portion 12, a core fitting side outer peripheral groove 11v is formed in an annular shape at a predetermined axial position.

[0038] The nut member 20 has a hexagonal shape formed on its outer peripheral surface of the nut cylindrical main body 21, and a female thread 22 and a flat inner peripheral surface 23 are formed on the inner peripheral surface on both axial sides. An annular reduced-diameter portion 24 with a reduced inner diameter is formed at the end of the nut cylindrical main body 21 opposite to the female thread 22, and the inner peripheral surface of the annular reduced-diameter portion 24 is the flat inner peripheral surface 23. An annular recess 25 is formed on the inner peripheral surface of the nut member 20 between the female thread 22 and the annular reduced-diameter portion 24.

[0039] On the flat inner peripheral surface 23 which is the inner peripheral surface of the annular reduced diameter portion 24, an annular nut-side inner peripheral groove 23v is formed, and the nut-side inner peripheral groove 23v is formed at the opening edge portion on the female screw 22 side of the flat inner peripheral surface 23. Therefore, the nut-side inner peripheral groove 23v has a fan shape in cross section with a central angle smaller than 90 degrees, opens to the inside of the flat inner peripheral surface 23, and also opens to the annular recess 25 side.

[0040] Referring to FIG. 2, when comparing the groove depth d of the nut-side inner peripheral groove 23v of the nut member 20 and the groove depth D of the fitting-side outer peripheral groove 11v of the fitting cylindrical portion 11 of the core fitting 10, the groove depth D of the fitting-side outer peripheral groove 11v is deeper than the groove depth d of the nut-side inner peripheral groove 23v.

[0041] The inner diameter of the annular reduced diameter portion 24 of the nut member 20 is equal to the diameter of the cylindrical outer peripheral surface 11s of the fitting cylindrical portion 11 of the core fitting 10, and the axial width of the annular reduced diameter portion 24 is substantially equal to the width length between the fitting-side outer peripheral groove 11v of the fitting cylindrical portion 11 of the core fitting 10 and the hexagonal flange portion 12 of the core fitting 10. As shown in FIG. 3, when the annular reduced diameter portion 24 of the nut member 20 is fitted to the fitting cylindrical portion 11 of the core fitting 10 and inserted until the annular reduced diameter portion 24 abuts against the hexagonal flange portion 12 of the core fitting 10, the core fitting 10 and the nut member 20 are set in a predetermined relative positional relationship in the axial direction.

[0042] When the core fitting 10 and the nut member 20 are fitted in a predetermined relative positional relationship, as shown in FIG. 3, the female screw 22 of the nut member 20 is located axially outside the fitting cylindrical portion 11 of the core fitting 10, and the annular reduced diameter portion 24 of the nut member 20 is fitted to the cylindrical outer peripheral surface 11s between the fitting-side outer peripheral groove 11v of the fitting cylindrical portion 11 of the core fitting 10 and the hexagonal flange portion 12 of the core fitting 10. Therefore, the fitting-side outer peripheral groove 11v and the nut-side inner peripheral groove 23v coincide with each other, and a ring insertion hole V is formed. And due to the annular recess 25 formed between the female screw 22 and the annular reduced diameter portion 24 of the nut member 20, a gap S is formed between the core fitting cylindrical portion 11 inside the nut member 20.

[0043] The ring insertion hole V formed by the outer peripheral groove 11v on the core fitting side and the inner peripheral groove 23v on the nut side is substantially circular with a partially missing cross-sectional shape. However, since the groove depth D of the outer peripheral groove 11v on the core fitting side is deeper than the groove depth d of the inner peripheral groove 23v on the nut side, the ring insertion hole V is located on the core fitting cylindrical portion 11 side rather than on the nut member 20 side, and the cross-sectional shape is exactly an oval shape where the outer peripheral groove 11v on the core fitting side is slightly longer.

[0044] As shown in FIG. 4, the locking ring 30 inserted into the ring insertion hole V is a ring having elasticity formed in a C-shaped arc with a part of the ring missing, and the inner diameter is equal to or slightly smaller than the diameter of the bottom surface forming the annular shape of the outer peripheral groove 11v on the core fitting side. The cross-sectional shape of the locking ring 30 is circular.

[0045] As shown in FIG. 3, the gap S formed between the core fitting cylindrical portion 11 by the annular recess 25 on the inner peripheral surface of the nut member 20 communicates between the inner opening of the female thread 22 and the ring insertion hole V. Therefore, the locking ring 30 can be easily inserted from the inner opening of the female thread 22, passed along the conical end face 11t of the core fitting cylindrical portion 11 while expanding the diameter, and inserted into the ring insertion hole V.

[0046] As shown in FIG. 1, when the locking ring 30 is inserted into the ring insertion hole V, the nut member 20 is restricted from relative movement in the axial direction away from the core fitting 10 and locked so as to be relatively rotatable by the locking ring 30, and the nut member 20 is attached to the core fitting 10, and the pipe joint 1 is configured.

[0047] In this way, in order to restrict the relative movement of the nut member 20 in the axial direction away from the core fitting 10 and lock it so as to be relatively rotatable by the locking ring 30, the locking ring 30 can be easily and appropriately inserted into the ring insertion hole V without the need for dedicated equipment. The cost can be suppressed.

[0048] As shown in Fig. 5, the fitting metal fitting 40 connected to the pipe joint 10 has a cylindrical shape with a flow passage through which fluid flows inside, and has a hexagonal flange portion 43 with a hexagonal outer shape at the center, and fitting metal fitting cylindrical portions 41, 41 forming the outflow inlets protrude on both sides of the hexagonal flange portion 43. On the outer peripheral surface of the fitting metal fitting cylindrical portion 41, a male thread 42 that can be screwed into the female thread 22 of the nut member 20 is formed.

[0049] The inner peripheral surface of the fitting metal fitting cylindrical portion 41 has a diameter equal to the diameter of the inner peripheral surface of the ferrule cylindrical portion 11 of the ferrule 10. The end face of the fitting metal fitting cylindrical portion 41 is a conical end face 41t that is inclined with respect to the axial direction and has an inner diameter that increases towards the tip. Referring to Fig. 5, the inclination of the conical end face 41t of the fitting metal fitting cylindrical portion 41 with respect to the axial direction is the same as the inclination of the conical end face 11t of the ferrule cylindrical portion 11 facing it with respect to the axial direction.

[0050] Therefore, when the pipe joint 1 screws and tightens the female thread 22 of the nut member 20 fitted and locked to the ferrule cylindrical portion 11 of the ferrule 10 onto the male thread 42 of the fitting metal fitting cylindrical portion 41 of the fitting metal fitting 40, the conical end face 11t of the ferrule cylindrical portion 11 bites into the inside of the conical end face 41t of the fitting metal fitting cylindrical portion 41 and is press - contacted with a large contact area. Thus, a large static frictional force acts and the ferrule cylindrical portion 11 and the fitting metal fitting cylindrical portion 41 are firmly connected. Therefore, even if there is pressure fluctuation in the fluid flowing inside the ferrule cylindrical portion 11 and the fitting metal fitting cylindrical portion 41, fluid leakage can be prevented (see Fig. 6).

[0051] The ferrule - side outer peripheral groove 11v and the nut - side inner peripheral groove 23v that constitute the ring insertion hole V into which the locking ring 30 is inserted are biased towards the ferrule cylindrical portion 11 side of the ring insertion hole V because the groove depth D of the ferrule - side outer peripheral groove 11v is deeper than the groove depth d of the nut - side inner peripheral groove 23v.

[0052] When the female thread 22 of the nut member 20 is screwed onto the male thread 42 formed on the fitting cylinder portion 41 of the joint fitting 40 and tightened with the required torque, on the outer peripheral side portion that fits into the nut-side inner peripheral groove 23v with a shallow groove depth and the inner peripheral side portion that fits into the ferrule-side outer peripheral groove 11v with a deep groove depth of the locking ring 30, pressing forces in opposite directions in the axial direction are applied to each other. Due to the deformation along the mating surfaces (cylindrical outer peripheral surface 11s, flat inner peripheral surface 23) of the ferrule cylinder portion 11 of the locking ring 30 and the annular reduced-diameter portion 24 of the nut member 21, especially when the mating surface is biased toward the nut member 20 side, it is considered that deformation such that a pressing force sufficient to buckle the opening edge of the ferrule-side outer peripheral groove 11v is less likely to occur, and deformation of the ferrule-side outer peripheral groove 11v is avoided.

[0053] Therefore, by avoiding deformation of the ferrule-side outer peripheral groove 11v of the ferrule 10, the pressure contact between the ferrule cylinder portion 11 and the joint fitting cylinder portion 41 can be strongly maintained without weakening, no gap is generated, and fluid leakage can be prevented.

[0054] This is not only when the female thread 22 of the nut member 20 is screwed onto and tightened with the male thread 42 formed on the joint fitting cylinder portion 41, but also when pressure fluctuations of the fluid flowing inside the pipe joint 1 repeat. Since the locking ring 30 does not press and deform the opening edge of the ferrule-side outer peripheral groove 11v, even when the pipe joint 1 is used for a long time, the pressure contact between the ferrule cylinder portion 11 and the joint fitting cylinder portion 41 can be strongly maintained without weakening, and fluid leakage can be prevented.

[0055] In addition to being able to strongly maintain the pressure contact between the ferrule cylinder portion 11 and the joint fitting cylinder portion 41 by forming the ring insertion hole V biased toward the ferrule cylinder portion 11 side in this way, in this first embodiment, the conical end faces 11t, 41t of the ferrule cylinder portion 11 and the joint fitting cylinder portion 41 are pressure contacted with a large contact area, so that the ferrule cylinder portion 11 and the joint fitting cylinder portion 41 are firmly connected. Thus, even when there are pressure fluctuations in the fluid, fluid leakage can be more reliably prevented (see Fig. 6).

[0056] Note that while the pipe joint 1 is connected to one of the joint fitting cylindrical portions 41 of the joint fitting 40, another pipe joint may be connected to the other joint fitting cylindrical portion 41, or a fluid device may be directly connected thereto.

[0057] Next, a modified example of the pipe joint according to the first embodiment will be described with reference to FIG. 7. In this modified example, the end faces where the core fitting cylindrical portion and the joint fitting cylindrical portion are in pressure contact with each other are conical end faces 11t', 41t' having an inclination with respect to the axial direction. However, compared with the conical end faces 11t, 41t in the pipe joint according to the first embodiment, this is an example in which the direction of inclination with respect to the axial direction is reversed. Except for the conical end faces 11t', 41t' with the reverse inclination direction, the rest is the same as in the first embodiment, so the same reference numerals will be used for the description.

[0058] That is, the end face of the core fitting cylindrical portion 11 forming the inlet / outlet of the core fitting 10 is a conical end face 11t' having an inclination with respect to the axial direction and with an inner diameter increasing towards the tip. On the other hand, the end face of the joint fitting cylindrical portion 41 forming the inlet / outlet of the joint fitting 40 is a conical end face 41t' having an inclination with respect to the axial direction and with an outer diameter decreasing towards the tip. The inclination of the conical end face 41t' of the joint fitting cylindrical portion 41 with respect to the axial direction is the same as the inclination of the conical end face 11t' of the core fitting cylindrical portion 11 facing it with respect to the axial direction.

[0059] Therefore, when the female thread 22 of the nut member 20 fitted into the core fitting cylindrical portion 11 of the core fitting 10 and locked by the locking ring 30 is screwed and tightened onto the male thread 42 of the joint fitting cylindrical portion 41 of the joint fitting 40 in this pipe joint 1, the conical end face 41t' of the joint fitting cylindrical portion 41 bites into the inside of the conical end face 11t' of the core fitting cylindrical portion 11 and is pressure contacted with a large contact area. Thus, a large static frictional force acts to firmly connect the core fitting cylindrical portion 11 and the joint fitting cylindrical portion 41. Therefore, combined with the fact that the ring fitting hole V is formed to be biased towards the core fitting cylindrical portion 11 side, the pressure contact between the core fitting cylindrical portion 11 and the joint fitting cylindrical portion 41 can be strongly maintained, more reliably preventing fluid leakage and allowing fluid to flow.

[0060] In the above example, the end faces where the core fitting cylindrical portion and the joint fitting cylindrical portion are in pressure contact with each other are conical end faces having an inclination with respect to the axial direction. However, the end faces where the core fitting cylindrical portion and the joint fitting cylindrical portion are in pressure contact with each other may be flat faces perpendicular to the axial direction.

[0061] Next, the pipe joint 50 according to the second embodiment will be described with reference to FIGS. 8 to 12. FIG. 8 is a side view showing a partial cross section of the pipe joint 50 according to the second embodiment, and FIG. 9 is an exploded side view showing a partial cross section of the same pipe joint 50. The pipe joint 50 is configured by combining a core fitting 60 fixed to the end of a hose 68 which is a pipe body, a nut member 70, and a locking ring 80.

[0062] The core fitting 60 has the same shape as the core fitting 10 of the pipe joint 1 according to the first embodiment, and has core fitting cylindrical portions 61, hexagonal flange portions 62, cylindrical stepped portions 63, and small-diameter cylindrical portions 64 of the same shape. The core fitting cylindrical portion 61 has a conical end face 61t having an inclination with respect to the axial direction and a decreasing outer diameter toward the tip. On the cylindrical outer peripheral surface 61s between the conical end face 61t and the hexagonal flange portion 62, a core fitting side outer peripheral groove 61v is formed in an annular shape at a predetermined position in the axial direction.

[0063] Also, similar to the first embodiment, the end of the hose 68 is fitted onto the outer periphery of the small-diameter cylindrical portion 64 of the core fitting 60 and clamped by a clamping fitting 19, so that the end of the hose 68 is firmly fixed to the core fitting 60.

[0064] On the other hand, the nut member 70 has a hexagonal shape formed on the outer peripheral surface of a nut cylindrical main body 71, and a female thread 72 and a flat inner peripheral surface 73 are formed side by side in the axial direction on the inner peripheral surface. The diameter of the flat inner peripheral surface 73 of the nut member 70 is equal to the diameter of the cylindrical outer peripheral surface 61s of the core fitting cylindrical portion 61 of the core fitting 60. A nut side inner peripheral groove 73v is formed at a predetermined position in the axial direction of the flat inner peripheral surface 73 of the nut member 70.

[0065] Referring to FIG. 9, when comparing the groove depth d of the nut-side inner peripheral groove 73v formed in the flat inner peripheral surface 73 of the nut member 70 with the groove depth D of the fitting-side outer peripheral groove 61v formed in the cylindrical outer peripheral surface 61s of the fitting cylindrical portion 61 of the core fitting 60, the groove depth D of the fitting-side outer peripheral groove 61v is slightly deeper than the groove depth d of the nut-side inner peripheral groove 73v.

[0066] The axial width between the side surface on the flat inner peripheral surface 73 side of the nut cylindrical main body 71 of the nut member 70 and the nut-side inner peripheral groove 73v is equal to the axial width between the hexagonal flange portion 62 of the core fitting 10 and the fitting-side outer peripheral groove 61v. Therefore, as shown in FIG. 10, when the flat inner peripheral surface 73 of the nut member 70 is fitted to the fitting cylindrical portion 61 of the core fitting 60 and inserted until the nut cylindrical main body 71 abuts against the hexagonal flange portion 62 of the core fitting 60, the core fitting 60 and the nut member 70 are set in a predetermined relative positional relationship in the axial direction.

[0067] When the core fitting 60 and the nut member 70 are fitted in a predetermined relative positional relationship, as shown in FIG. 10, the female thread 72 of the nut member 70 is located axially outside the fitting cylindrical portion 61, and the portion between the flat inner peripheral surface 73 of the nut member 70, the nut-side inner peripheral groove 73v, and the side surface of the nut cylindrical main body 71 fits between the fitting-side outer peripheral groove 61v of the fitting cylindrical portion 61 and the hexagonal flange portion 62 of the core fitting 60. Therefore, the fitting-side outer peripheral groove 11v and the nut-side inner peripheral groove 23v coincide, and the ring insertion hole V is formed.

[0068] The ring insertion hole V formed by the fitting-side outer peripheral groove 61v and the nut-side inner peripheral groove 73v has a circular cross-sectional shape, and the groove depth D of the fitting-side outer peripheral groove 61v is slightly deeper than the groove depth d of the nut-side inner peripheral groove 73v.

[0069] In the nut member 70 formed with such a nut-side inner peripheral groove 73v, as shown in FIG. 11, a pin insertion hole 74 extending in the tangential direction of the inner peripheral circle of the nut-side inner peripheral groove 73v is formed to penetrate outward in the tangential direction from the nut-side inner peripheral groove 73v.

[0070] The core fitting 60 and the nut member 70 are fitted in a predetermined relative positional relationship, and the ring insertion hole V formed by the alignment of the outer peripheral groove 61v on the core fitting side and the inner peripheral groove 73v on the nut side has a circular cross section, and the pin insertion hole 74 has a circular cross section with the same shape as the ring insertion hole V. Therefore, as shown in FIG. 11, the pin insertion hole 74 extends in the tangential direction of the ring of the ring insertion hole V and is formed to penetrate outward in the tangential direction from the ring insertion hole V.

[0071] By inserting the flexible pin 80 into the pin insertion hole 74 of the nut member 70 and further entering the ring insertion hole V, the pin 80 is deformed circularly along the inner peripheral groove 73v on the nut side and is inserted into the ring insertion hole V to form an annular locking ring 80 (see FIG. 8). The locking ring 80 fits into both the outer peripheral groove 61v on the core fitting side with the groove depth D forming the ring insertion hole V and the inner peripheral groove 73v on the nut side with the groove depth d.

[0072] Thus, as shown in FIG. 8, when the locking ring 30 is inserted into the ring insertion hole V, the nut member 70 is restricted from relative movement in the direction away from the axial core fitting 10 with respect to the core fitting 60 and is locked and attached so as to be relatively rotatable, and the pipe joint 50 is configured. Note that the nut member 70 is restricted from relative movement in the axial direction with respect to the core fitting 60, not limited to the direction away from the axial core fitting 10.

[0073] In this way, in order to restrict the relative movement of the nut member 70 in the direction away from the axial core fitting 60 with respect to the core fitting 60 and lock and attach it so as to be relatively rotatable by the locking ring 80, the pin 80 is inserted into the pin insertion hole 74 and then inserted into the ring insertion hole V, so that the locking ring 80 can be easily and appropriately inserted into the ring insertion hole V, and no dedicated equipment is required. The cost can be reduced.

[0074] The fitting metal 90 connected to the pipe joint 50 has the same shape as the fitting metal 40 according to the first embodiment, and has fitting metal cylindrical portions 91, conical end faces 91t, male threads 92, and hexagonal flange portions 93 of the same shape.

[0075] Therefore, when the pipe joint 50 is fitted into the fitting metal cylindrical portion 61 of the core fitting 60 and the female thread 72 of the nut member 70 locked by the locking ring 80 is screwed and tightened onto the male thread 92 of the fitting metal cylindrical portion 91 of the fitting metal 90, the conical end face 61t of the fitting metal cylindrical portion 61 bites into the inside of the conical end face 91t of the fitting metal cylindrical portion 91 and is pressure-welded with a large contact area. Thus, a large static frictional force acts and the fitting metal cylindrical portion 61 and the fitting metal cylindrical portion 91 are firmly connected. Therefore, even if there is pressure fluctuation in the fluid flowing inside the fitting metal cylindrical portion 61 and the fitting metal cylindrical portion 91, fluid leakage can be prevented (see Fig. 12).

[0076] The outer peripheral groove 61v on the core fitting side and the inner peripheral groove 73v on the nut side that constitute the ring fitting hole V into which the locking ring 80 is inserted are biased toward the core fitting cylindrical portion 61 side because the groove depth D of the outer peripheral groove 61v on the core fitting side is deeper than the groove depth d of the inner peripheral groove 73v on the nut side.

[0077] When the female thread 72 of the nut member 70 is screwed onto the male thread 92 formed on the fitting metal cylindrical portion 91 of the fitting metal 90 and tightened with the required torque, pressing forces in opposite axial directions are applied to the outer peripheral side portion fitted into the inner peripheral groove 73v with a shallow groove depth of the locking ring 80 and the inner peripheral side portion fitted into the outer peripheral groove 61v with a deep groove depth on the core fitting side. Along the mating surface (cylindrical outer peripheral surface 61s, flat inner peripheral surface 73) between the core fitting cylindrical portion 81 of the locking ring 80 and the annular reduced diameter portion 74 of the nut member 71, particularly since the mating surface is biased toward the nut member 70 side, it is considered that deformation such as buckling of the opening edge of the outer peripheral groove 61v on the core fitting side is less likely to occur, and deformation of the outer peripheral groove 61v on the core fitting side is avoided.

[0078] Therefore, by avoiding deformation of the outer peripheral groove 61v on the core fitting side of the core fitting 60, the pressure contact between the core fitting cylindrical portion 61 and the joint fitting cylindrical portion 91 can be strongly maintained without weakening it, no gap is generated, and fluid leakage can be prevented. This means that even if the pressure of the fluid flowing inside the pipe joint 50 fluctuates repeatedly during long-term use of the pipe joint 50, the pressure contact between the core fitting cylindrical portion 61 and the joint fitting cylindrical portion 91 can be similarly maintained strongly, no gap is generated, and fluid leakage can be prevented.

[0079] In addition to being able to strongly maintain the pressure contact between the core fitting cylindrical portion 61 and the joint fitting cylindrical portion 91 by forming the ring insertion hole V biased toward the core fitting cylindrical portion 61 in this way, in this second embodiment, the conical end faces 61t and 91t of the core fitting cylindrical portion 61 and the joint fitting cylindrical portion 91 are pressure contacted with a large contact area, so that the core fitting cylindrical portion 61 and the joint fitting cylindrical portion 91 are firmly connected. Thus, even if there is a pressure fluctuation of the fluid, fluid leakage can be more reliably prevented (see FIG. 12).

[0080] As described above, the pipe joint according to the embodiment of the present invention has been described. However, the aspect of the present invention is not limited to the above embodiment, and includes those implemented in various aspects within the scope of the gist of the present invention. Also, the joint fitting connected to the above pipe joint is not limited to the joint fitting shown in the embodiment, and various joint fittings can be considered. Furthermore, in this embodiment, the end of the hose is fixed to the core fitting. However, the present invention is applicable not only to hoses but also to pipe joints in which a pipe body such as a steel pipe is connected to the core fitting.

[0081] The present invention can prevent fluid leakage even if there is a pressure fluctuation of the fluid flowing inside the pipe joint, and the pipe joint can be used for a long time.

Explanation of Reference Numerals

[0082] 1... Pipe joint 10…Core fitting, 11…Cylindrical part of core fitting, 11t, 11t´…Conical end faces, 11s…Cylindrical outer peripheral surface, 11v…Outer peripheral groove on the core fitting side, 12…Hexagonal flange part, 13…Cylindrical stepped part, 14…Small-diameter cylindrical part, 18…Hose, 19…Clamping fitting, 20…Nut member, 21…Nut cylindrical main body, 22…Female thread, 23…Flat inner peripheral surface, 23v…Inner peripheral groove on the nut side, 24…Annular reduced-diameter part, 25…Annular recess, 30…Locking ring, 40…Joint fitting, 41…Cylindrical part of joint fitting, 41t, 41t´…Conical end faces, 42…Male thread, 43…Hexagonal flange part, 50…Pipe joint, 60…Core fitting, 61…Cylindrical part of core fitting, 61t…Conical end face, 61s…Cylindrical outer peripheral surface, 61v…Outer peripheral groove on the core fitting side, 62…Hexagonal flange part, 63…Cylindrical stepped part, 64…Small-diameter cylindrical part, 68…Hose, 69…Clamping fitting, 70…Nut member, 71…Nut cylindrical main body, 72…Female thread, 73…Flat inner peripheral surface, 73v…Inner peripheral groove on the nut side, 74…Pin insertion hole, 80…Locking ring (pin), 90…Joint fitting, 91…Cylindrical part of joint fitting, 91t…Conical end face, 92…Male thread, 93…Hexagonal flange part.

Claims

1. A pipe joint in which a nut member (20; 70) having an internal thread (22; 72) and a flat internal peripheral surface (23; 73) formed on both axial sides thereof on the inner peripheral surface of a nut cylindrical main body (21; 71) is coaxially disposed with the internal thread (22; 72) outside the core fitting cylindrical portion (11; 61) in the axial direction and the flat internal peripheral surface (23; 73) is fitted to the core fitting cylindrical portion (11; 61) forming the outflow and inflow ports of the core fitting (10; 60) connected to the pipe body (18; 68), and the nut member (20; 70) is locked to the core fitting (10; 60) so as to be restricted from relative movement in the direction away from the core fitting (10; 60) in the axial direction and rotatable relative thereto, In the pipe joint in which the internal thread (22; 72) of the nut member (20; 70) is screwed onto and tightened against an external thread (42; 92) formed on a joint fitting cylindrical portion (41; 91) forming the outflow and inflow ports of the joint fitting (40; 90), thereby connecting the joint fitting cylindrical portion (41; 91) to the core fitting cylindrical portion (11; 61) via the nut member (20; 70), An outer peripheral groove (11v; 61v) on the core fitting side is formed in an annular shape on the outer peripheral surface of the core fitting cylindrical portion (11; 61), An inner peripheral groove (23v; 73v) on the nut side is formed in an annular shape on the flat inner peripheral surface (23; 73) of the nut member (20; 70), When the nut member (20; 70) with the flat inner peripheral surface (23; 73) fitted coaxially to the core fitting cylindrical portion (11; 61) of the core fitting (10; 60) is in a predetermined relative positional relationship with respect to the core fitting (10; 60) in the axial direction, the outer peripheral groove (11v; 61v) on the core fitting side and the inner peripheral groove (23v; 73v) on the nut side are aligned to form a ring insertion hole (V), By inserting a locking ring (30; 80) into the ring insertion hole (V), the nut member (20; 70) is locked to the core fitting (10; 60) so as to be restricted from relative movement in the direction away from the core fitting (10; 60) in the axial direction and rotatable relative thereto, The pipe joint is characterized in that the outer peripheral groove (11v; 61v) on the core fitting side is deeper in groove depth than the inner peripheral groove (23v; 73v) on the nut side.

2. When the female thread (22; 72) of the nut member (20; 70) is screwed onto and tightened with the male thread (42; 92) of the joint fitting cylindrical portion (41; 91), the end face of the core fitting cylindrical portion (11; 61) and the end face of the joint fitting cylindrical portion (41; 91) are in pressure contact and connected. The pipe joint according to claim 1, characterized in that.

3. The end faces (11t, 41t; 61t, 91t) where the core fitting cylindrical portion (11; 61) and the joint fitting cylindrical portion (41; 91) are in pressure contact with each other are conical surfaces having an inclination with respect to the axial direction. The pipe joint according to claim 2, characterized in that.

4. The locking ring (30) is an elastic ring formed in a C-shaped arc. The nut member (20) has an annular reduced-diameter portion (24) with an inner diameter that is reduced at the end opposite to the female thread (22) of the nut cylindrical body (21) and is equal to the outer diameter of the core fitting cylindrical portion (11), and has a flat inner peripheral surface (23). A nut-side inner peripheral groove (23v) is formed at the opening edge portion on the female thread side of the flat inner peripheral surface (23) of the annular reduced-diameter portion (24). When the nut member (20) is in a predetermined relative positional relationship in the axial direction where the core fitting-side outer peripheral groove (11v) and the nut-side inner peripheral groove (23v) coincide with respect to the core fitting (10), an annular recess (25) formed between the female thread (22) on the inner peripheral surface of the nut cylindrical body (21) and the annular reduced-diameter portion (24) forms a gap (S) between the nut member (20) and the core fitting cylindrical portion (11) inside the nut member (20). The pipe joint according to any one of claims 1 to 3, characterized in that.

5. A pin insertion hole (74) extending in the tangential direction of the inner peripheral circle of the nut-side inner peripheral groove (73v) is formed in the nut member (70) so as to penetrate outward in the tangential direction from the nut-side inner peripheral groove (73v). The pipe joint according to any one of claims 1 to 3, characterized in that a flexible pin (80) is inserted into the pin insertion hole (74) and further inserted into the ring insertion hole (V) to form the locking ring (80).

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