Pipe joint

Abstract

Disclosed is a pipe joint in which, when a nut member 20;70 in which a flat inner circumferential surface 23;73 is fitted coaxially on a core metal fitting cylindrical part 11 of a core metal fitting 10;60 is in a predetermined positional relationship in the axial direction with respect to the core metal fitting 10;60, a core metal fitting-side outer circumferential groove 11v;61v and a nut-side inner circumferential groove 23v;73v are matched to form a ring fitting hole V, and by fitting of a locking ring 30;80 in the ring fitting hole V, the nut member 20;70 is locked and attached to the core metal fitting 10;60 so as to be rotatable relative thereto and restricted from moving relative thereto in the direction away from the core metal fitting 10;60 in the axial direction, and because the groove depth of the core metal fitting-side outer circumferential groove 11v;61v is greater than the groove depth of the nut-side inner circumferential groove 23v;73v, the pipe joint can be assembled easily and appropriately without requiring dedicated equipment, and leakage of fluid can be prevented during fastening of the nut member and when the pressure of the fluid fluctuates.

Description

Pipe fittings

[0001] The present invention relates to a pipe joint in which a core fitting is connected to a joint fitting via a nut member.

[0002] The pipe fitting of the present invention is a pipe fitting having a structure in which the female thread of a nut member fitted to the core fitting connected to the pipe body is screwed onto and tightened with the male thread formed on the cylindrical portion of the joint fitting which forms the inlet and outlet of the joint fitting.

[0003] In this type of pipe joint, when the nut member is fitted to the core metal, the nut member needs to be attached so that its relative movement in the axial direction away from the core metal is restricted and it can rotate relative to the core metal. Examples of such pipe joints include those using a crimp nut (for example, Patent Document 1).

[0004] Japanese Patent Publication No. 2020-90991

[0005] The pipe fitting disclosed in Patent Document 1 consists of a fitting body (corresponding to a core metal fitting) fixed to the end of a hose, and a crimping nut having a nut portion at one end of a cylindrical portion and a protrusion portion protruding inward at the other end.

[0006] The crimping nut is attached by coaxially placing the nut portion on the cylindrical portion of the joint body where the outlet of the joint body is located, with the nut portion axially outward from the cylindrical portion of the joint body; the end of the cylindrical portion with the protrusion is crimped radially inward to plastically deform the cylindrical portion; and the protrusion of the crimping nut is accommodated in a groove formed on the outer surface of the cylindrical portion of the joint body so that it can rotate relative to the joint body.This restricts relative movement of the crimping nut in the axial direction away from the joint body, and allows it to be attached so that it is engaged and rotatable relative to the joint body.

[0007] By screwing the tightening nut attached to the joint body in this way onto the male thread formed on the cylindrical portion that forms the inlet and outlet of the joint fitting and tightening it, the joint body and the joint fitting are connected by pressure contact.

[0008] In this way, the tubular portion is plastically deformed by tightening the tightening nut, and the protrusion is accommodated in the recessed groove of the joint body, and the joint body and joint fitting are press-fitted and connected by tightening the nut portion.

[0009] The pressure of the fluid flowing through the joint body and the joint fitting acts in a direction that separates the joint body and the joint fitting, so the crimp nut, along with the joint body, is subjected to a force in a direction that moves it away from the joint fitting, and a force in the opening direction acts on the tubular portion of the crimp nut, which has been plastically deformed in the closing direction.When high-pressure fluid flows frequently and pressure fluctuations are repeated, stress is repeatedly exerted on the tubular portion of the crimp nut in the opening direction, and if the crimp nut is overtightened, the tubular portion undergoes deformation opposite to the plastic deformation, weakening the pressure connection between the joint body and the joint fitting, creating a gap that could allow fluid to leak.

[0010] Furthermore, when attaching a crimp nut to a joint body, the end of the tubular portion of the crimp nut, which has a protrusion, is crimped radially inward to plastically deform the tubular portion. However, if the deformation is insufficient, the protrusion may not catch sufficiently and may come off. If the deformation is excessive, the protrusion may come into pressure contact with the bottom or side of the groove in the joint body, making it difficult to rotate. Therefore, it is difficult to crimp the crimp nut with appropriate precision, and since the end of the tubular portion of the crimp nut, which has the protrusion, must be crimped radially inward evenly around the entire circumference, dedicated crimping equipment is required.

[0011] Therefore, the inventors have devised a structure for a pipe fitting that does not require dedicated equipment and can be assembled easily and properly, in which a locking ring is interposed between the core fitting and the nut member, so that the nut member is locked and attached so that relative movement in the axial direction away from the core fitting is restricted and the nut member can rotate relative to the core fitting.

[0012] In other words, when the nut member, which is coaxially fitted into the cylindrical portion of the core metal fitting that forms the inlet / outlet of the core metal fitting, is at a predetermined axial position, the core metal fitting side outer peripheral groove formed on the outer surface of the cylindrical portion of the core metal fitting and the nut side inner peripheral groove formed on the flat inner surface of the nut member match to form a common ring insertion hole, and by inserting a locking ring into this ring insertion hole, the nut member is locked to the core metal fitting by the locking ring, restricting relative movement away from the core metal fitting in the axial direction and allowing relative rotation.

[0013] Assembly can be easily and properly achieved by fitting a locking ring into a ring insertion hole formed in common on the mating surfaces of the core metal and the nut member. The female thread of the nut member, whose relative movement in the axial direction away from the core metal is restricted by the locking ring, is then threaded onto the male thread formed on the cylindrical portion of the coupling metal that forms the inlet / outlet, and the coupling metal can be connected by bringing it close to the core metal and tightening it.

[0014] However, when the nut member is tightened with the torque required to connect the coupling fitting to the core fitting, the core fitting-side outer peripheral groove of the core fitting is sometimes buckled and deformed by the pressure of the locking ring. When the core fitting-side outer peripheral groove is buckled and deformed, the pressure connection between the coupling body and the coupling fitting weakens, creating a gap that can cause fluid leakage.

[0015] As a result of intensive research, the inventors have come to the following discovery: The pipe joint originally under consideration had a ring insertion hole formed in common on the mating surfaces of the core metal fitting and the nut member, and was structured so that the ring insertion hole was evenly positioned on both the core metal fitting and the nut member, i.e., the core metal fitting-side outer peripheral groove and the nut side inner peripheral groove were equal in depth, and therefore the outer peripheral half of the locking ring inserted into this ring insertion hole was fitted into the nut side inner peripheral groove, and the inner peripheral half was fitted into the core metal fitting-side outer peripheral groove.

[0016] When the female thread of the nut member is screwed onto the male thread formed on the cylindrical portion of the coupling fitting which forms the inlet / outlet and tightened with the required torque, a pressing force is applied in opposite axial directions to the outer half of the locking ring fitted into the inner groove on the nut side and the inner half fitted into the outer groove on the core fitting side, causing the locking ring to easily deform along the mating surfaces of the cylindrical portion of the core fitting and the nut member.When the locking ring deforms, a pressing force acts on the opening edge of the outer groove on the core fitting side which is prone to buckling, causing it to buckle and deform.

[0017] Furthermore, in pipe fittings in which the ring insertion hole formed in common on the mating surfaces of the core fitting and the nut member is positioned biased toward the nut member, when the female thread of the nut member is screwed onto the male thread of the cylindrical portion of the fitting and tightened with the required torque, the outer peripheral groove on the core fitting side of the core fitting may buckle and deform.

[0018] Based on the above findings, the inventor discovered that deformation of the core metal can be avoided by devising a method of contact between the core metal side outer peripheral groove and the nut side inner peripheral groove of the locking ring.

[0019] The present invention has been made in consideration of the above points, and its object is to provide a pipe fitting that does not require dedicated equipment, can be assembled simply and appropriately, and can prevent fluid leakage by avoiding deformation of the core metal fitting when the nut member is tightened and the fluid pressure fluctuates.

[0020] In order to achieve the above object, the present invention provides a pipe coupling in which a nut member, on the inner peripheral surface of a nut cylindrical body of which is formed a female thread and flat inner peripheral surfaces on both axial sides, is fitted onto a core fitting cylindrical portion that forms the inlet and outlet of a core fitting connected to a pipe body, with the flat inner peripheral surface being coaxially fitted with the female thread on the axially outer side of the core fitting cylindrical portion, and the nut member is attached to the core fitting such that relative movement in the axial direction away from the core fitting is restricted and the nut member is locked so as to be rotatable relative to the core fitting, and the female thread of the nut member is screwed onto a male thread formed on the coupling fitting cylindrical portion that forms the inlet and outlet of the coupling fitting, and the pipe coupling connects the coupling fitting cylindrical portion to the core fitting cylindrical portion via the nut member, and the female thread of the nut member is screwed onto a male thread formed on the coupling fitting cylindrical portion that forms the inlet and outlet of the coupling fitting, and the pipe coupling When the nut member, whose flat inner peripheral surface is coaxially fitted to the cylindrical portion of the core metal fitting, is in a predetermined relative axial positional relationship with respect to the core metal fitting, the core metal fitting side outer peripheral groove and the nut side inner peripheral groove align to form a ring insertion hole, and by inserting a locking ring into the ring insertion hole, the nut member is attached to the core metal fitting so that relative movement in the axial direction away from the core metal fitting is restricted and the nut member is locked and attached so as to be able to rotate relative to the core metal fitting, and the core metal fitting side outer peripheral groove is deeper than the nut side inner peripheral groove.

[0021]

[0003] With this configuration, when the female thread of the nut member is threaded onto the male thread formed on the cylindrical portion of the coupling fitting and tightened with the required torque, pressing forces are applied in opposite axial directions to the outer peripheral portion of the locking ring that fits into the shallow nut-side inner circumferential groove and the inner peripheral portion that fits into the deep core-side outer circumferential groove, causing deformation along the mating surfaces of the locking ring and the cylindrical portion of the core fitting. In particular, because the mating surfaces are biased toward the nut member, deformation that would apply pressing forces sufficient to buckle the opening edge of the core-side outer circumferential groove is unlikely to occur, and deformation of the core-side outer circumferential groove of the core fitting is avoided. Therefore, the pressure contact between the cylindrical portion of the core fitting and the cylindrical portion of the coupling fitting can be maintained strong without weakening, no gaps are created, and fluid leakage can be prevented.

[0022] Furthermore, the flat inner peripheral surface of the nut member contacts the outer peripheral surface of the coaxial core metal cylindrical portion, and a locking ring is fitted into the ring insertion hole formed by the core metal side outer peripheral groove and the nut side inner peripheral groove matching in a predetermined relative axial positional relationship, thereby restricting the relative movement of the nut member in the axial direction away from the core metal and locking and attaching it so that it can rotate relative to the core metal, thereby making assembly easy and appropriate without requiring any special dedicated equipment.

[0023] In a preferred embodiment of the present invention, when the female thread of the nut member is threaded onto the male thread of the coupling fitting cylindrical portion and tightened, the end faces of the core fitting cylindrical portion and the coupling fitting cylindrical portion are pressed together to connect them.

[0024] According to this configuration, when the nut member is tightened by screwing the female thread onto the male thread of the coupling fitting cylindrical portion, the end faces of the core fitting cylindrical portion and the coupling fitting cylindrical portion are pressed together to connect them, allowing smooth flow through the insides of the connected core fitting cylindrical portion and coupling fitting cylindrical portion.

[0025] In a preferred embodiment of the present invention, the end surfaces of the core metal cylindrical portion and the coupling metal cylindrical portion, which are brought into pressure contact with each other, are conical surfaces inclined with respect to the axial direction.

[0026] According to this configuration, the end surfaces where the core fitting cylindrical portion and the coupling fitting cylindrical portion are pressed against each other are conical surfaces inclined with respect to the axial direction, so that one conical (end) surface bites into the inside of the other conical (end) surface and is pressed against each other with a large contact area, resulting in a large static friction force that firmly connects the core fitting cylindrical portion and the coupling fitting cylindrical portion.In addition, the ring insertion hole is formed biased toward the core fitting cylindrical portion, which allows the core fitting cylindrical portion and the coupling fitting cylindrical portion to be strongly pressed against each other.This means that even if there are pressure fluctuations in the fluid flowing inside the core fitting cylindrical portion and the coupling fitting cylindrical portion, leakage of fluid can be more reliably prevented.

[0027] In a preferred embodiment of the present invention, the locking ring is an elastic ring formed in a C-arc shape, the nut member has an annular reduced diameter portion formed at the end opposite to the female thread of the nut cylindrical body, the inner diameter of which is reduced and the flat inner circumferential surface has an inner diameter equal to the outer diameter of the core metal cylindrical portion, the nut side inner circumferential groove is formed at the opening edge portion on the female thread side of the flat inner circumferential surface of the annular reduced diameter portion, and when the nut member is in a predetermined axial relative positional relationship with respect to the core metal so that the core metal side outer circumferential groove and the nut side inner circumferential groove coincide, a gap is formed between the core metal cylindrical portion inside the nut member and the annular reduced diameter portion due to the annular recess formed between the female thread on the inner circumferential surface of the nut cylindrical body and the annular reduced diameter portion.

[0028] According to this configuration, when the nut member is positioned relative to the core member in a predetermined axial positional relationship in which the core member side outer peripheral groove and the nut member side inner peripheral groove match, the gap formed between the nut member and the cylindrical portion of the core member by the annular recess of the nut member communicates with the nut member side inner peripheral groove and the core member side outer peripheral groove formed at the female thread side opening edge portion of the flat inner peripheral surface of the annular reduced diameter portion.Therefore, the elastic locking ring formed in a C-arc shape can be easily inserted into the ring insertion hole in which the nut member side inner peripheral groove and the core member side outer peripheral groove match, through the gap formed by the annular recess, while being expanded in diameter.The locking ring inserted into this ring insertion hole restricts relative movement of the nut member in the axial direction away from the core member and is attached so as to be capable of relative rotation, so assembly can be made easier and more appropriate without the need for special dedicated equipment.

[0029] In a preferred embodiment of the present invention, the nut member is formed with a pin insertion hole extending in a tangential direction to the inner circumference of the nut side inner circumferential groove, penetrating from the nut side inner circumferential groove outward in the tangential direction, and a flexible pin is inserted into the pin insertion hole and then fitted into the ring fitting hole to form the locking ring.

[0030] According to this configuration, a flexible pin is inserted into the pin insertion hole, and then fitted into an arc-shaped ring insertion hole formed by the matching of the deep outer peripheral groove on the core metal fitting side and the shallow inner peripheral groove on the nut side to form a locking ring.This makes it easier to fit the locking ring into the ring insertion hole, and the locking ring fitted into this ring insertion hole restricts the relative movement of the nut member in the axial direction away from the core metal fitting and engages and attaches it so that it can rotate relatively, making assembly easier and more appropriate without the need for special dedicated equipment.

[0031] In the present invention, when the female thread of the nut member is threaded onto the male thread formed on the cylindrical portion of the coupling fitting and tightened with the required torque, pressing forces are applied in opposite axial directions to the outer peripheral portion of the locking ring that fits into the shallow inner circumferential groove on the nut side and the inner peripheral portion that fits into the deep outer circumferential groove on the core fitting side. However, because the mating surfaces of the cylindrical portion of the core fitting and the nut member are biased toward the nut member, there is no deformation of the locking ring along the mating surface, and in particular no deformation that would apply a pressing force strong enough to buckle the opening edge of the outer circumferential groove on the core fitting side. This allows for strong pressure contact between the coupling body and the coupling fitting, no gaps to form, and prevents fluid leakage.

[0032] Furthermore, by fitting the locking ring into the ring insertion hole formed by the matching outer peripheral groove on the core metal fitting side and the inner peripheral groove on the nut side, the relative movement of the nut member in the axial direction away from the core metal fitting is restricted and the nut member is fitted so as to be able to rotate relative to the core metal fitting, thereby enabling easy and proper assembly without the need for special dedicated equipment.

[0033] 10 is a partially sectional side view of a pipe fitting according to a first embodiment of the present invention. FIG. 11 is an exploded partially sectional side view of the pipe fitting. FIG. 12 is a partially sectional side view with a nut member fitted onto the core fitting and the locking ring disassembled. FIG. 13 is a front view of the locking ring. FIG. 14 is an exploded partially sectional side view of the pipe fitting and the coupling fitting. FIG. 15 is a partially sectional side view of the pipe fitting according to the first embodiment, with a coupling fitting connected via a nut member. FIG. 16 is a partially sectional side view of a pipe fitting according to a second embodiment of the present invention. FIG. 17 is an exploded partially sectional side view of the pipe fitting. FIG. 18 is a partially sectional side view of the pipe fitting with the nut member fitted onto the core fitting. FIG. 19 is a cross-sectional view taken along arrows XI-XI in FIG. 10. FIG. 19 is a partially sectional side view of the pipe fitting connected via a nut member.

[0034] A first embodiment of the present invention will now be described with reference to Figures 1 to 6. Figure 1 is a side view, partially in section, of a pipe fitting 1 according to the first embodiment, and Figure 2 is an exploded side view, partially in section, of the same pipe fitting 1. The pipe fitting 1 is formed by combining a core metal fitting 10, a nut member 20, and a locking ring 30, which are secured to the end of a hose 18, which is a pipe body.

[0035] Referring to Figure 2, the core metal fitting 10 is cylindrical with a flow passage inside through which a fluid flows, and has a hexagonal flange portion 12 with a hexagonal outer shape in the center. On one side of the hexagonal flange portion 12, a core metal cylindrical portion 11 which forms an inlet and outlet protrudes in the axial direction, and on the other side of the hexagonal flange portion 12, a cylindrical step portion 13 is formed which has an outer diameter smaller than that of the hexagonal flange portion 12, and a small-diameter cylindrical portion 14 which has an outer diameter further reduced and has unevenness formed on its outer surface extends in the axial direction from the cylindrical step portion 13.

[0036] The small diameter cylindrical portion 14 of the core metal fitting 10 is fitted into the end of a flexible hose 18, whose inner diameter is slightly smaller than the outer diameter of the small diameter cylindrical portion 14 and whose outer diameter is slightly larger than the outer diameter of the cylindrical step portion 13.A cylindrical crimping metal fitting 19 is fitted onto the outer surface of the end of the hose 18 and the outer surface of the cylindrical step portion 13 of the core metal fitting 10, and is crimped radially inward, so that the inner surface of the hose 18 bites into the unevenness of the outer surface of the small diameter cylindrical portion 14, and the end of the hose 18 is firmly fixed to the core metal fitting 10.

[0037] The end face of the core metal cylindrical portion 11, which forms the inlet / outlet of the core metal 10, is a conical end face 11t that is inclined with respect to the axial direction and whose outer diameter becomes smaller toward the tip. A core metal side outer peripheral groove 11v is formed in an annular shape at a predetermined axial position on the cylindrical outer peripheral surface 11s between the conical end face 11t of the core metal cylindrical portion 11 and the hexagonal flange portion 12.

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

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

[0040] Referring to Figure 2, when comparing the groove depth d of the nut side inner circumferential groove 23v of the nut member 20 with the groove depth D of the core metal side outer circumferential groove 11v of the core metal cylindrical portion 11 of the core metal 10, the groove depth D of the core metal side outer circumferential groove 11v is deeper than the groove depth d of the nut side inner circumferential 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 circumferential surface 11s of the core metal cylindrical portion 11 of the core metal 10, and the axial width of the annular reduced diameter portion 24 is approximately equal to the width between the core metal-side outer circumferential groove 11v of the core metal cylindrical portion 11 and the hexagonal flange portion 12 of the core metal 10. As shown in Figure 3, when the annular reduced diameter portion 24 of the nut member 20 is fitted into the core metal cylindrical portion 11 of the core metal 10 until the annular reduced diameter portion 24 abuts against the hexagonal flange portion 12 of the core metal 10, the core metal 10 and the nut member 20 are set in a predetermined relative positional relationship in the axial direction.

[0042] 3, when the core metal 10 and the nut member 20 are fitted together in a predetermined relative positional relationship, the female thread 22 of the nut member 20 is located axially outward from the core metal cylindrical portion 11, and the annular reduced diameter portion 24 of the nut member 20 is fitted onto the cylindrical outer circumferential surface 11s between the core metal cylindrical portion 11 and the hexagonal flange portion 12 of the core metal 10, so that the core metal outer circumferential groove 11v and the nut side inner circumferential groove 23v match up to form a ring insertion hole V. Then, a gap S is formed between the core metal cylindrical portion 11 and the nut member 20 due to the annular recess 25 formed between the female thread 22 and the annular reduced diameter portion 24 of the nut member 20.

[0043] The ring insertion hole V, which is formed by the core metal side outer peripheral groove 11v and the nut side inner peripheral groove 23v, has a cross-sectional shape that is approximately circular with a portion missing, but since the groove depth D of the core metal side outer peripheral groove 11v is deeper than the groove depth d of the nut side inner peripheral groove 23v, the ring insertion hole V is positioned more biased toward the core metal cylindrical portion 11 than the nut member 20, and the cross-sectional shape is, to be precise, an oval with the core metal side outer peripheral groove 11v being slightly longer.

[0044] The locking ring 30 to be fitted into the ring fitting hole V is an elastic ring formed into a C-arc shape with a portion of the ring missing, as shown in Figure 4, and its inner diameter is equal to or slightly smaller than the diameter of the annular bottom surface of the core metal side outer peripheral groove 11v. The cross section of the locking ring 30 is circular.

[0045] 3, the gap S formed between the nut member 20 and the cylindrical core metal portion 11 by the annular recess 25 on the inner peripheral surface thereof communicates with 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, and passed through the gap S along the conical end face 11t of the cylindrical core metal portion 11 while expanding its diameter, and inserted into the ring insertion hole V.

[0046] As shown in Figure 1, when the locking ring 30 is inserted into the ring insertion hole V, the locking ring 30 restricts the relative movement of the nut member 20 in the axial direction away from the core metal fitting 10 and locks it so that it can rotate relative to the core metal fitting 10, thereby attaching the nut member 20 to the core metal fitting 10 and forming the pipe fitting 1.

[0047] In this way, the locking ring 30 restricts the relative movement of the nut member 20 in the axial direction away from the core metal 10 and allows it to be locked and attached so as to be rotatable relative to the core metal 10. However, the locking ring 30 can be easily and appropriately fitted into the ring insertion hole V, and no dedicated equipment is required, thereby reducing costs.

[0048] 5, the coupling fitting 40 connected to the pipe coupling 10 is cylindrical with an internal flow passage through which a fluid flows, and has a hexagonal flange portion 43 with a hexagonal outer shape in the center, with coupling fitting cylindrical portions 41, 41 forming inlet and outlet ports protruding on both sides of the hexagonal flange portion 43. The coupling fitting cylindrical portion 41 has an external thread 42 formed on its outer periphery that can be threaded onto the internal thread 22 of the nut member 20.

[0049] The diameter of the inner peripheral surface of the coupling fitting cylindrical portion 41 is equal to the diameter of the inner peripheral surface of the core fitting cylindrical portion 11 of the core fitting 10. The end face of the coupling fitting cylindrical portion 41 is a conical end face 41t that is inclined with respect to the axial direction and whose inner diameter increases toward the tip. Referring to Figure 5, the inclination of the conical end face 41t of the coupling 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 that faces it with respect to the axial direction.

[0050] Therefore, when the female thread 22 of the nut member 20, which is fitted and locked onto the core fitting cylindrical portion 11 of the core fitting 10, is threaded onto the male thread 42 of the coupling fitting cylindrical portion 41 of the coupling fitting 40 and tightened, the conical end surface 11t of the core fitting cylindrical portion 11 bites into the inside of the conical end surface 41t of the coupling fitting cylindrical portion 41 and is pressed against it with a large contact area, resulting in a large static friction force that firmly connects the core fitting cylindrical portion 11 and the coupling fitting cylindrical portion 41, preventing fluid leakage even if there are pressure fluctuations in the fluid flowing inside the core fitting cylindrical portion 11 and the coupling fitting cylindrical portion 41 (see Figure 6).

[0051] The core metal fitting side outer peripheral groove 11v and the nut side inner peripheral groove 23v that form the ring insertion hole V into which the locking ring 30 is inserted have a groove depth D of the core metal fitting side outer peripheral groove 11v that is deeper than the groove depth d of the nut side inner peripheral groove 23v, so the ring insertion hole V is biased toward the core metal fitting cylindrical portion 11.

[0052] When the female thread 22 of the nut member 20 is threaded onto the male thread 42 formed on the coupling fitting cylindrical portion 41 of the coupling fitting 40 and tightened with the required torque, pressing forces are applied in opposite axial directions to the outer peripheral portion of the locking ring 30 fitted into the shallow nut side inner circumferential groove 23v and the inner peripheral portion fitted into the deep core fitting side outer circumferential groove 11v, causing deformation along the mating surfaces (cylindrical outer peripheral surface 11s, flat inner circumferential surface 23) between the core fitting cylindrical portion 11 of the locking ring 30 and the annular reduced diameter portion 24 of the nut member 21. In particular, because the mating surfaces are biased toward the nut member 20, it is believed that deformation that applies a pressing force strong enough to buckle the opening edge of the core fitting side outer circumferential groove 11v is unlikely to occur, and deformation of the core fitting side outer circumferential groove 11v is avoided.

[0053] Therefore, deformation of the core metal fitting side outer peripheral groove 11v of the core metal fitting 10 is avoided, and the pressure contact between the core metal fitting cylindrical portion 11 and the coupling metal fitting cylindrical portion 41 can be maintained strong without weakening, and gaps are not created, preventing fluid leakage.

[0054] This is not only true when the female thread 22 of the nut member 20 is threaded onto the male thread 42 formed on the coupling fitting cylindrical portion 41 and tightened, but also when there are repeated pressure fluctuations in the fluid flowing inside the pipe coupling 1, the locking ring 30 will not press against the opening edge of the core fitting side outer peripheral groove 11v and deform it, so even when the pipe coupling 1 is used for a long period of time, the pressure contact between the core fitting cylindrical portion 11 and the coupling fitting cylindrical portion 41 will not weaken, and the pressure contact can be maintained strong, preventing fluid leakage.

[0055] In this way, by forming the ring insertion hole V biased toward the core metal cylindrical portion 11, it is possible to maintain a strong pressure contact between the core metal cylindrical portion 11 and the coupling metal cylindrical portion 41.In addition, in this first embodiment, the conical end faces 11t, 41t of the core metal cylindrical portion 11 and the coupling metal cylindrical portion 41 are pressed together with a large contact area, thereby firmly connecting the core metal cylindrical portion 11 and the coupling metal cylindrical portion 41, and more reliably preventing fluid leakage even if there are fluctuations in fluid pressure (see Figure 6).

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

[0057] Next, a modified example of the pipe fitting according to the first embodiment will be described with reference to Figure 7. In this modified example, the end faces where the core fitting cylindrical portion and the coupling fitting cylindrical portion are pressed together are conical end faces 11t', 41t' that are inclined relative to the axial direction, but this is an example in which the direction of inclination relative to the axial direction is opposite to that of the conical end faces 11t, 41t in the pipe fitting according to the first embodiment. Since the other components are the same as those in the first embodiment, the same reference numerals will be used in the description.

[0058] That is, the end face of the core metal cylindrical portion 11 that forms the inlet / outlet of the core metal 10 is inclined with respect to the axial direction and is a conical end face 11t' whose inner diameter increases toward the tip. On the other hand, the end face of the coupling fitting cylindrical portion 41 that forms the inlet / outlet of the coupling fitting 40 is a conical end face 41t' that is inclined with respect to the axial direction and whose outer diameter decreases toward the tip. The inclination of the conical end face 41t' of the coupling fitting cylindrical portion 41 with respect to the axial direction is the same as the inclination of the conical end face 11t' of the opposing core metal cylindrical portion 11 with respect to the axial direction.

[0059] Therefore, when this pipe fitting 1 is fitted onto the core fitting cylindrical portion 11 of the core fitting 10 and the female thread 22 of the nut member 20 locked by the locking ring 30 is screwed onto the male thread 42 of the coupling fitting cylindrical portion 41 of the coupling fitting 40 and tightened, the conical end surface 41t' of the coupling fitting cylindrical portion 41 bites into the inside of the conical end surface 11t' of the core fitting cylindrical portion 11 and is pressed against each other with a large contact area, resulting in a large static friction force that firmly connects the core fitting cylindrical portion 11 and the coupling fitting cylindrical portion 41.This, combined with the fact that the ring insertion hole V is formed biased toward the core fitting cylindrical portion 11, allows the strong pressure contact between the core fitting cylindrical portion 11 and the coupling fitting cylindrical portion 41 to be maintained, more reliably preventing fluid leakage and allowing fluid to flow.

[0060] In the above examples, the end surfaces where the core fitting cylindrical portion and the coupling fitting cylindrical portion are pressed against each other are conical end surfaces inclined with respect to the axial direction, but the end surfaces where the core fitting cylindrical portion and the coupling fitting cylindrical portion are pressed against each other may also be flat surfaces perpendicular to the axial direction.

[0061] Next, a pipe fitting 50 according to a second embodiment will be described with reference to Figures 8 to 12. Figure 8 is a side view, partially in section, of the pipe fitting 50 according to the second embodiment, and Figure 9 is an exploded side view, partially in section, of the same pipe fitting 50. The pipe fitting 50 is configured by combining a core metal fitting 60, a nut member 70, and a locking ring 80, which are secured to the end of a hose 68, which is a pipe body.

[0062] The core fitting 60 has the same shape as the core fitting 10 of the pipe fitting 1 according to the first embodiment, and has the same shaped core fitting cylindrical portion 61, hexagonal flange portion 62, cylindrical step portion 63, and small diameter cylindrical portion 64. The core fitting cylindrical portion 61 has a conical end surface 61t that is inclined with respect to the axial direction and the outer diameter becomes smaller toward the tip, and a core fitting side outer peripheral groove 61v is formed in a circular shape at a predetermined axial position on the cylindrical outer peripheral surface 61s between the conical end surface 61t and the hexagonal flange portion 62.

[0063] Furthermore, as in 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 metal fitting 60 and tightened with the tightening fitting 19, thereby firmly fixing the end of the hose 68 to the core metal fitting 60.

[0064] On the other hand, the nut member 70 has a hexagonal shape formed on the outer peripheral surface of the nut cylindrical body 71, and an internal thread 72 and a flat inner peripheral surface 73 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 metal cylindrical portion 61 of the core metal 60. A nut-side inner peripheral groove 73v is formed at a predetermined axial position on the flat inner peripheral surface 73 of the nut member 70.

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

[0066] The axial width between the side surface on the flat inner peripheral surface 73 side of the nut cylindrical 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 metal 10 and the core metal-side outer peripheral groove 61v. Therefore, as shown in Figure 10, when the flat inner peripheral surface 73 of the nut member 70 is fitted into the core metal cylindrical portion 61 of the core metal 60 until the nut cylindrical body 71 abuts against the hexagonal flange portion 62 of the core metal 60, the core metal 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 together in a predetermined relative positional relationship, as shown in Figure 10, the female thread 72 of the nut member 70 is located axially outward from the core fitting cylindrical portion 61, and the portion between the flat inner surface 73 of the nut member 70, the nut side inner peripheral groove 73v, and the side of the nut cylindrical body 71 is fitted between the core fitting side outer peripheral groove 61v of the core fitting cylindrical portion 61 and the hexagonal flange portion 62 of the core fitting 60, so that the core fitting side outer peripheral groove 11v and the nut side inner peripheral groove 23v match up, forming a ring insertion hole V.

[0068] The ring insertion hole V, which is composed of the core metal 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 core metal 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 having such a nut side inner peripheral groove 73v formed therein, as shown in Figure 11, a pin insertion hole 74 extending in the tangential direction of the inner circumference of the nut side inner peripheral groove 73v is formed so as to penetrate from the nut side inner peripheral groove 73v outward in the tangential direction.

[0070] When the core metal fitting 60 and the nut member 70 are fitted together in a predetermined relative positional relationship and the core metal fitting side outer peripheral groove 61v and the nut side inner peripheral groove 73v are aligned to form a ring insertion hole V, which has a circular cross section, and the pin insertion hole 74 has the same circular cross section as the ring insertion hole V. Therefore, as shown in Figure 11, the pin insertion hole 74 extends in the tangential direction of the annulus of the ring insertion hole V and is formed by penetrating from the ring insertion hole V outward in the tangential direction.

[0071] A flexible pin 80 is inserted into the pin insertion hole 74 of this nut member 70 and then enters the ring insertion hole V, whereby the pin 80 is fitted into the ring insertion hole V while deforming into a circular shape along the nut-side inner circumferential groove 73v, forming an annular locking ring 80 (see Figure 8). The locking ring 80 fits into both the core metal-side outer circumferential groove 61v with a groove depth D that forms the ring insertion hole V, and the nut-side inner circumferential groove 73v with a groove depth d.

[0072] 8, when the locking ring 30 is fitted into the ring fitting hole V, the nut member 70 is restricted from moving relative to the core metal 60 in the axial direction away from the core metal 10 and is locked and attached so as to be rotatable relative to the core metal 60, thereby forming the pipe joint 50. Note that the nut member 70 is restricted from moving relative to the core metal 60 in the axial direction, not just in the direction away from the core metal 10.

[0073] In this way, the locking ring 80 restricts the relative movement of the nut member 70 in the axial direction away from the core metal fitting 60 and locks and attaches it so that it can rotate relative to the core metal fitting 60. By inserting the pin 80 into the pin insertion hole 74 and then fitting it into the ring fitting hole V, the locking ring 80 can be easily and appropriately fitted into the ring fitting hole V, and no dedicated equipment is required, thereby reducing costs.

[0074] As shown in FIG. 12 , the coupling fitting 90 to be connected to the pipe coupling 50 has the same shape as the coupling fitting 40 according to the first embodiment, and has the same shaped coupling fitting cylindrical portion 91, conical end surface 91t, male thread 92, and hexagonal flange portion 93.

[0075] Therefore, when the pipe fitting 50 is fitted onto the core fitting cylindrical portion 61 of the core fitting 60 and the female thread 72 of the nut member 70, which is locked by the locking ring 80, is screwed onto the male thread 92 of the coupling fitting cylindrical portion 91 of the coupling fitting 90 and tightened, the conical end surface 61t of the core fitting cylindrical portion 61 bites into the inside of the conical end surface 91t of the coupling fitting cylindrical portion 91 and is pressed against it with a large contact area, resulting in a large static friction force that firmly connects the core fitting cylindrical portion 61 and the coupling fitting cylindrical portion 91, preventing fluid leakage even if there are pressure fluctuations in the fluid flowing inside the core fitting cylindrical portion 61 and the coupling fitting cylindrical portion 91 (see Figure 12).

[0076] The core metal fitting side outer peripheral groove 61v and the nut side inner peripheral groove 73v that form the ring insertion hole V into which the locking ring 80 is inserted have a groove depth D of the core metal fitting side outer peripheral groove 61v that is deeper than the groove depth d of the nut side inner peripheral groove 73v, so the ring insertion hole V is biased toward the core metal fitting cylindrical portion 61.

[0077] When the female thread 72 of the nut member 70 is threaded onto the male thread 92 formed on the coupling fitting cylindrical portion 91 of the coupling fitting 90 and tightened with the required torque, pressing forces are applied in opposite axial directions to the outer peripheral portion of the locking ring 80 fitted into the shallow nut side inner circumferential groove 73v and the inner peripheral portion fitted into the deep core fitting side outer circumferential groove 61v, causing deformation along the mating surfaces (cylindrical outer peripheral surface 61s, flat inner circumferential 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. In particular, because the mating surfaces are biased toward the nut member 70, it is believed that deformation that applies a pressing force strong enough to buckle the opening edge of the core fitting side outer circumferential groove 61v is unlikely to occur, and deformation of the core fitting side outer circumferential groove 61v is avoided.

[0078] Therefore, deformation of the core fitting-side outer peripheral groove 61v of the core fitting 60 is avoided, so that the pressure contact between the core fitting cylindrical portion 61 and the coupling fitting cylindrical portion 91 can be maintained strong without weakening, no gaps are created, and fluid leakage can be prevented. This means that even when the pipe fitting 50 is used for a long period of time and there are repeated pressure fluctuations in the fluid flowing inside the pipe fitting 50, the pressure contact between the core fitting cylindrical portion 61 and the coupling fitting cylindrical portion 91 can be similarly maintained strong, no gaps are created, and fluid leakage can be prevented.

[0079] In this way, by forming the ring insertion hole V biased toward the core fitting cylindrical portion 61, it is possible to maintain a strong pressure contact between the core fitting cylindrical portion 61 and the coupling fitting cylindrical portion 91.In addition, in this second embodiment, the conical end faces 61t, 91t of the core fitting cylindrical portion 61 and the coupling fitting cylindrical portion 91 are pressed together with a large contact area, thereby firmly connecting the core fitting cylindrical portion 61 and the coupling fitting cylindrical portion 91, and more reliably preventing fluid leakage even if there are fluctuations in fluid pressure (see Figure 12).

[0080] While the pipe fitting according to the embodiment of the present invention has been described above, the aspects of the present invention are not limited to the above-described embodiment and include various embodiments within the scope of the present invention. Furthermore, the fittings connected to the pipe fittings are not limited to those shown in the embodiment, and various fittings are conceivable. Furthermore, while in this embodiment the end of the hose is fixed to the core fitting, the present invention is also applicable to pipe fittings in which a tubular body, such as a steel pipe, is connected to a core fitting, not limited to a hose.

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

[0082] 1...pipe joint, 10...core metal fitting, 11...core metal fitting cylindrical portion, 11t, 11t'...conical end surface, 11s...cylindrical outer peripheral surface, 11v...core metal fitting side outer peripheral groove, 12...hexagonal flange portion, 13...cylindrical step portion, 14...small diameter cylindrical portion, 18...hose, 19...crimping metal fitting, 20...nut member, 21...nut cylindrical body, 22...female thread, 23...flat inner peripheral surface, 23v...nut side inner peripheral groove, 24...annular reduced diameter portion, 25...annular recess, 30...locking ring, 40...joint metal fitting, 41...joint metal fitting cylindrical portion, 41t, 41t'...conical end surface, 42...male thread, 43...hexagonal flange portion, 50...pipe joint, 60...core metal fitting, 61...core metal fitting cylindrical portion, 61t...conical end face, 61s...cylindrical outer peripheral surface, 61v...core metal fitting side outer peripheral groove, 62...hexagonal flange portion, 63...cylindrical step portion, 64...small diameter cylindrical portion, 68...hose, 69...crimping metal fitting, 70...nut member, 71...nut cylindrical body, 72...female thread, 73...flat inner peripheral surface, 73v...nut side inner peripheral groove, 74...pin insertion hole, 80...locking ring (pin), 90...joint metal fitting, 91...joint metal fitting cylindrical portion, 91t...conical end face, 92...male thread, 93...hexagonal flange portion.

Claims

1. A pipe fitting in which a nut member (20; 70) having an internal thread (22; 72) and a flat inner peripheral surface (23; 73) formed on both axial sides of an inner peripheral surface of a nut tubular body (21; 71) is fitted into a core fitting cylindrical portion (11; 61) that forms an inlet / outlet of a core fitting (10; 60) connected to a pipe body (18; 68), with the internal thread (22; 72) being axially outward of the core fitting cylindrical portion (11; 61) and the flat inner peripheral surface (23; 73) being coaxially engaged therewith, the nut member (20; 70) being restricted from moving relative to the core fitting (10; 60) in the axial direction away from the core fitting (10; 60) and being engaged so as to be capable of rotating relative to the core fitting, In a pipe fitting that connects the coupling fitting cylindrical portion (41; 91) to the core fitting cylindrical portion (11; 61) via the nut member (20; 70) by screwing and fastening the female thread (22; 72) of the nut member (20; 70) into the male thread (42; 92) formed on the coupling fitting cylindrical portion (41; 91) that constitutes the inlet / outlet of the coupling fitting (40; 90), a core fitting side outer peripheral groove (11v; 61v) is formed in an annular shape on the outer peripheral surface of the core fitting cylindrical portion (11; 61), a nut side inner peripheral groove (23v; 73v) is formed in an annular shape on the flat inner peripheral surface (23; 73) of the nut member (20; 70), a core fitting (10; 60) having a flat inner peripheral surface (23; 73) coaxially fitted into the core fitting cylindrical portion (11; 61) of the core fitting (10; 60), when the nut member (20; 70) is in a predetermined relative positional relationship in the axial direction with respect to the core fitting (10; 60), the core fitting side outer peripheral groove (11v; 61v) and the nut side inner peripheral groove (23v; 73v) match to form a ring insertion hole (V), and by inserting a locking ring (30; 80) into the ring insertion hole (V), the nut member (20; 70) is attached to the core fitting (10; 60) in such a way that relative movement in the axial direction away from the core fitting (10; 60) is restricted and the nut member (20; 70) is locked and attached so as to be capable of relative rotation, and the core fitting side outer peripheral groove (11v; 61v) has a greater groove depth than the nut side inner peripheral groove (23v; 73v).

2. A pipe fitting as described in claim 1, characterized in that when the female thread (22; 72) of the nut member (20; 70) is screwed into the male thread (42; 92) of the coupling fitting cylindrical portion (41; 91) and tightened, the end face of the core fitting cylindrical portion (11; 61) and the end face of the coupling fitting cylindrical portion (41; 91) are pressure welded and connected.

3. A pipe fitting as described in claim 2, characterized in that the end faces (11t, 41t; 61t, 91t) where the core fitting cylindrical portion (11; 61) and the fitting cylindrical portion (41; 91) are pressed against each other are conical surfaces inclined with respect to the axial direction.

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

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

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