Pipe joint construction

Abstract

To provide a pipe joint structure that is excellent in sealing performance, has high resistance to pulling force, can cope with large temperature changes of a sealed fluid, and has a long service life, a joint body 40 and a cap nut 15, 15 are connected to each other, and two pipes P, P to be connected are formed with a top end enlarged diameter pipe portion 5 from a top end surface over a predetermined axial dimension. A closed annular ring 25 is fitted outside the top end enlarged diameter pipe portion 5 over a tapered stepped portion 10 of the pipe P, and is connected by applying a pressing force to a connection cylinder portion 41 formed in a protruding manner at an end portion of the joint body 40.

Description

Technical Field

[0001] The present invention relates to a pipe joint structure, and in particular to a pipe joint structure for connecting pipes to each other. Background Art

[0002] All along, Figure 16 The flared joint shown in is well known. Generally speaking, as Figure 16 As shown in [1], this flared joint is formed by plastically working the flared portion f at the end of the pipe P using a tool (jig). The structure is as follows: the flared portion a is contacted with the tapered portion a of the flared joint body h and tightened with a cap nut n. The tapered surface t of the cap nut n and the tapered portion a of the flared joint body h are clamped together, ensuring sealing by the mutual pressure contact of the metal surfaces (see, for example, Patent Document 1). When a dedicated jig (tool) is used to form the flared portion f at the end of the connected pipe P during operation, the large plastic deformation toward the tapered shape easily causes cracks to form at the small-diameter corner f1 of the flared portion f. The cracking rate is particularly high when the pipe P is made of aluminum. Furthermore, (regardless of whether the pipe P is made of Cu or aluminum) there are problems with the flaring process performed at the operation site, which can lead to quality variations.

[0003] Therefore, it was proposed Figure 14 and Figure 15 A pipe joint structure having such a structure is shown in (see Patent Document 2).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-42858;

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2010-270846. Summary of the Invention

[0008] Problems to be solved by the invention

[0009] Figure 14 、 Figure 15 The pipe joint structure shown in FIG. 1 comprises a flared joint body 82 and a cap nut 83, with an internal pullout prevention member 81. This has the advantage of eliminating the need for flaring and other processing at the catheter tip. However, this requires pullout prevention member 81 with extremely precise claws 80. Consequently, there remain the issues of manufacturing difficulty and high cost. Furthermore, if rotational torque is applied to the catheter P, the claws 80 may form spiral grooves, causing the catheter to pull out.

[0010] Furthermore, in Figure 14、 Figure 15 The pipe joint structure requires sealing members such as O-rings 84 and 85. However, rubber O-rings 84 and 85 are difficult to withstand the large temperature fluctuations between -50°C and +130°C, and thus have problems with durability and sealing performance.

[0011] Therefore, the present invention aims to solve these problems by providing a union-type pipe joint structure that can eliminate ultra-precision components, is easy to manufacture, and can achieve cost reductions. It is compact and yet allows for stable and easy connection operations. Another object is to provide a pipe joint structure that can withstand the severe temperature fluctuations of the sealed fluid, has a long service life, and can connect suitable (union-type) pipes.

[0012] Solutions to Problems

[0013] Therefore, the present invention is constructed as follows: it comprises a flared joint body having male threaded portions and top diameter-reducing tapered portions on both sides in the axial direction, and a cap nut having a female threaded portion threadedly engaged with the male threaded portion, two mutually connected conduits having top diameter-reducing tube portions formed thereon from the top surfaces over a predetermined axial dimension, and a tapered step portion formed at the boundary between the top diameter-reducing tube portion and the base diameter tube portion, and an inner core having a connecting cylindrical portion inserted into the top diameter-reducing tube portion of the conduit and an inclined surface abutting against the top diameter-reducing tapered portion, through the above The cap nut is screwed into the thread of the flared joint body, and a closed annular ring is arranged inside the cap nut, which passes through the tapered step portion of the above-mentioned conduit and is externally embedded in the above-mentioned top diameter expanded tube portion. The radially inward diameter reduction biasing force of the above-mentioned ring is used to maintain the sealing state of the top diameter expanded tube portion of the above-mentioned conduit and the connecting cylindrical portion of the above-mentioned inner core. Furthermore, the axial force generated by the threaded engagement of the above-mentioned cap nut with the flared joint body is transmitted to the inner core via the above-mentioned ring, thereby maintaining the pressure-connected sealing state between the top diameter tapered portion of the above-mentioned flared joint body and the inclined surface of the inner core.

[0014] In addition, a plurality of independent small protrusions having a triangular or Mount Fuji-shaped cross section are formed on the outer peripheral surface of the connecting cylindrical portion of the inner core.

[0015] The present invention is further configured to include a joint body having a male threaded portion, a stepped portion, and a conduit connecting tube portion formed thereon in sequence on both sides in the axial direction, and two cap nuts having female threaded portions threadedly engaged with the male threaded portions. The two conduits to be connected to each other have a top expanded diameter tube portion formed thereon from the top end surface over a predetermined axial dimension, and a tapered stepped portion is formed at a boundary between the top expanded diameter tube portion and the base diameter tube portion. When the conduit connecting tube portion of the joint body is inserted into the top expanded diameter tube portion of the conduit, the cap nut is screwed into the thread of the joint body, and a closed annular ring is provided inside the cap nut, which passes through the tapered stepped portion of the conduit and is externally fitted to the top expanded diameter tube portion. The radially inward reducing biasing force of the ring maintains a sealed state between the top expanded diameter tube portion of the conduit and the conduit connecting tube portion of the joint body.

[0016] Furthermore, a plurality of independent small protrusions having a triangular or Mount Fuji-shaped cross section are formed on the outer peripheral surface of the pipe connecting cylinder portion protruding from the joint body.

[0017] In addition, sealing parts are completely omitted, and all components are made of metal.

[0018] In addition, if the wall thickness of the closed annular ring is set as T 25， And the wall thickness of the above-mentioned conduit is set to T p , then the size setting is Equation 1.

[0019] 1.0･T p ≦T 25 ≦2.5･T p (Formula 1)

[0020] Effects of the Invention

[0021] The present invention allows for relatively easy manufacturing without the need for ultra-precision components, while also providing a catheter with strong pull-out resistance. Rubber seals such as O-rings can be omitted, allowing the catheter to withstand temperature fluctuations from extremely low temperatures to extremely high temperatures (e.g., -70°C to +150°C), while maintaining a sufficiently high pull-out resistance.

[0022] While it is necessary to pre-process the catheter end with a large diameter tube, this can be done simply and reliably using a tool (jig) long used for brazing, eliminating the need for specialized skills. The presence of this large diameter tube ensures that the inner diameter of the flow path is the same as that of the catheter itself, minimizing any increase in resistance to fluid flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1This is a cross-sectional view showing a state in the middle of a connection operation according to one embodiment of the present invention.

[0024] Figure 2 yes Figure 1 Enlarged view of the main part.

[0025] Figure 3 It is a cross-sectional view showing a subsequent state of connection in progress.

[0026] Figure 4 It is a cross-sectional view of the main parts showing a connection completed state.

[0027] Figure 5 It is an overall cross-sectional view showing a connection completed state.

[0028] Figure 6 This is a cross-sectional view showing a state in the middle of a connection operation according to another embodiment of the present invention.

[0029] Figure 7 is a cross-sectional view of the connector body.

[0030] Figure 8 It is a cross-sectional view showing a subsequent state of connection in progress.

[0031] Figure 9 It is a cross-sectional view showing a connection completed state.

[0032] Figure 10 This is a cross-sectional view showing a connection completed state according to another embodiment.

[0033] Figure 11 It is a cross-sectional view of the main parts for explaining the exploded state.

[0034] Figure 12 This is a cross-sectional view illustrating the main parts of the operation tool for forming the distal end expanded tube portion and the method for expanding the diameter.

[0035] Figure 13 This is a cross-sectional view for explaining the brazing operation performed conventionally and currently, and illustrating the brazed pipe end portion.

[0036] Figure 14 This is a cross-sectional view showing a conventional example in a state where a connection operation is in progress.

[0037] Figure 15 1 is a cross-sectional view showing a connection completed state of a conventional example.

[0038] Figure 16 is a cross-sectional view showing another conventional example. DETAILED DESCRIPTION

[0039] Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

[0040] In Figure 1-Figure 5 one embodiment of the present application shown in FIG. 1, two connection pipes P, P connected to each other are formed with a tip diameter-increased pipe portion 5 from the tip end face 3 over a predetermined axial dimension L5.

[0041] At the boundary of the tip diameter-increased pipe portion 5 and a base diameter pipe portion 6 having a base diameter D0 of the pipe proper, a tapered step portion 10 is formed.

[0042] 20 is a flare joint body having one pair of male screw portions 20A and a tip diameter-decreased tapered portion 20B as left-right symmetrical, corresponds to a flare pipe joint prescribed in JIS B 8607, and is a piece same as the flare joint body h shown in Figure 16 .

[0043] 15 is a cap nut having a female screw portion 15A which is threadedly engaged with the male screw portion 20A of the flare joint body 20.

[0044] In the hole portion 16 of the cap nut 15, a large diameter female screw portion 15A, an intermediate diameter portion 15C, and a tip small diameter portion 15F (refer to Figure 2 ) are formed in this order from the base end to the tip end.

[0045] As described above, the pipe joint structure according to the present application is provided with the flare joint body 20 having the male screw portion 20A and the tip diameter-decreased tapered portion 20B, and the pair (two) of cap nuts 15, 15 having the female screw portions 15A which are threadedly engaged with the male screw portion 20A.

[0046] 30 is an inner core (in core) which is built in the cap nut 15 in the connected completed state as shown in Figure 4 , and the inner core 30 is provided with a connection cylinder portion 31 which is inserted into the tip diameter-increased pipe portion 5 of the pipe P, and an inclined surface 32 which abuts against the tip diameter-decreased tapered portion 20B of the joint body 20. Further, as shown in Figure 1 and Figure 5 , the two inner cores 30, 30 are arranged as left-right symmetrical across the flare joint body 20.

[0047] If further explained in detail, the inner core 30 has a through hole 33 along the axis, and the inclined surface 32 is formed at the base end side of the through hole 33, and is tapered in the base end direction, and is desirably slightly convex (convexly rounded). Also, with respect to the inner core 30, the base end portion is a thick wall large diameter portion 34 having a larger diameter than the connection cylinder portion 31, and between the thick wall large diameter portion 34 and the connection cylinder portion 31 (of small diameter), a step portion 35 is formed (refer to Figure 2 ).

[0048] Furthermore, a plurality of independent small protrusions 36 having a triangular or Mount Fuji-shaped cross section are formed on the outer peripheral surface of the connecting cylindrical portion 31 of the inner core 30 .

[0049] In addition, 25 is a closed annular ring, which is composed of a short cylinder. Figure 1 and Figure 2 As shown in FIG, before the forming process of the distal end expanded diameter tube portion 5, the ring 25 is fitted externally with respect to the catheter P in a movable fitting manner. Figure 12 In this way, the top expanded tube portion 5 is formed, and the ring 25 touches the tapered step portion 10 and does not move toward the top side of the catheter P (towards Figure 2 to the left of the

[0050] As from Figures 2 to 3 As shown in FIG, if the cap nut 15 is gently moved to the left (by hand), the ring 25 is fitted into the medium diameter portion 15C of the cap nut 15. That is, the cap nut 15 has an inner flange portion 17 at the top end (a small diameter portion 15F is formed on the inner circumference of the inner flange portion 17), and the inner surface 17A of the inner flange portion 17 is in contact with the top end surface of the ring 25 (see FIG. Figure 3 、 Figure 4 、 Figure 5 ).

[0051] As from Figures 2 to 3 In this way, if the cap nut 15 is brought close to the joint body 20 and then screwed into the male thread portion 20A of the joint body 20, the ring 25 inside the cap nut 15 is pressed axially inward by the inner surface 17A of the inner flange portion 17 and, at the same time, gradually moves toward the distal end of the catheter and abuts against the tapered step 10 of the catheter P.

[0052] The inner diameter of the ring 25 is set to be smaller than the outer diameter of the free state of the distal end enlarged tube portion 5 of the catheter P. Therefore, if the cap nut 15 is screwed in further, the cap nut 15 is screwed in as shown in FIG. Figures 3 and 4 、 Figure 5 In this way, the ring 25 passes through the tapered step 10 of the catheter P and is externally fitted into the top diameter enlarged tube portion 5. Moreover, a large force (pressing force) is applied in the diameter-reducing direction, and the independent small protrusions 36 are in a state of biting into the inner peripheral surface of the top diameter enlarged tube portion 5, as shown in FIG. Figure 4 As shown in the figure, the inner peripheral surface of the top expanded diameter tube portion 5 and the outer peripheral surface of the connecting cylindrical portion 31 of the inner core 30 are sealed as metals intertwined (compression-bonded state), preventing the sealed fluid (gas or liquid) from leaking outside.

[0053] In other words, the radially inward contraction biasing force (elastic biasing force) of the metal ring 25 can maintain the sealed state between the distal enlarged tube portion 5 of the catheter P and the connecting cylindrical portion 31 of the inner core 30 .

[0054] Furthermore, the axial force generated by the threaded engagement of the cap nut 15 with the flared joint body 20 is transmitted to the inner core 30 via the ring 25, thereby maintaining the press-fit sealing state between the top end tapered portion 20B of the flared joint body 20 and the inclined surface 32 of the inner core 30 (see FIG. Figures 3 and 4 、 Figure 5 ).

[0055] In addition, in Figures 1 to 5 When performing the connection operation as shown in FIG, it is ideal to complete the connection of either left or right side before performing the connection of the other side.

[0056] As from Figure 1-Figure 5 As is apparent, the pipe joint structure of the present invention completely omits rubber or synthetic resin sealing members such as O-rings. In other words, the components are all made of metal. Specifically, the pipe P is made of Cu or Al, the flare fitting body 20 is made of brass, the cap nut 15 is made of brass, the inner core 30 is made of brass or stainless steel, and the ring 25 is made of hard Al or stainless steel.

[0057] Next, in order to make the ring 25 exert a larger elastic biasing force in the direction of reducing the diameter of the distal end enlarged tube portion 5 of the catheter P, if the wall thickness dimension T of the ring 25 is 25 The wall thickness T of the pipe P p In comparison, it is ideally large enough.

[0058] For example, it can be set so that the following equation 1 holds true.

[0059] 1.0･T p ≦T 25 ≦2.5･T p (Formula 1)

[0060] Furthermore, it is ideal to set it as shown in the following formula 2.

[0061] 1.2･T p ≦T 25 ≦2.2･T p (Formula 2)

[0062] In addition, in T 25 When the pressure is less than the lower limit, the extrusion force in the radial direction is too small and the sealing is insufficient. On the contrary, if the upper limit is exceeded, it is difficult to screw the ring 25 from the cap nut 15 by screwing the cap nut 15. Figure 3 Towards Figure 4 state or from the following Figure 8 Towards Figure 9 The state of chimera.

[0063] Then, in Figure 6-Figure 9Hereinafter, another embodiment of the present invention will be described.

[0064] Reference numeral 40 denotes the connector body, which has a male threaded portion 37, a stepped portion 38, and a conduit connecting tube 41 integrally formed on both sides of the connector in the axial direction. A bulge 39 for hooking (holding) a tool such as a wrench or spanner is also integrally formed in the center of the connector in the axial direction.

[0065] Cap nut 15 is Figure 1-Figure 5 The structure described in the above is substantially the same, but the dimension in the axial direction is shorter. The female thread portion 15A of the cap nut 15 is threadedly engaged with the male thread portion 37 of the joint body 40.

[0066] The two connected pipes P and P have a distal expanded diameter portion 5 formed from the distal end surface 3 over a predetermined axial dimension L5. A tapered step 10 is formed at the boundary between the distal expanded diameter portion 5 and the basic diameter portion 6.

[0067] It is clear that Figure 6-Figure 9 In another embodiment shown in FIG, the ( Figure 1-Figure 5 ) The closed annular rings 25, 25 are also omitted, and the top end tapered portion 20B is also omitted.

[0068] However, in another embodiment, a conduit connecting cylinder 41 is formed to protrude integrally from the joint body 40 , and a plurality of independent small protrusions 36 having a triangular or Mount Fuji-shaped cross section are formed on the outer peripheral surface of the connecting cylinder 41 .

[0069] The step size ΔD of the step portion 38 is large enough, and the wall thickness size T of the conduit connecting cylinder 41 is large enough. 41 Formed smaller (refer to Figure 7 ).

[0070] Then, when the catheter connecting tube portion 41 of the joint body 40 is inserted into the distal end enlarged tube portion 5 of the catheter P, (as shown in FIG. Figure 8 As shown in FIG), the cap nut 15 is screwed into the joint body 40, and then moves in the direction of arrow K, and at the same time passes through the tapered step 10 and is Figure 9 The closed annular ring 25 fitted onto the distal end enlarged diameter tube portion 5 is provided inside the cap nut 15 .

[0071] exist Figure 9 In the connection completion state shown in FIG, the radially inward biasing force of the ring 25 is used to maintain the sealed state between the distal end enlarged tube portion 5 of the catheter P and the catheter connecting cylinder portion 41 of the joint body 40.

[0072] That is, by giving a large force (extrusion force) in the diameter-reducing direction by the ring 25, the independent small protrusions 36 become a state of biting into the inner peripheral surface of the tip diameter-increased tube portion 5, like Figure 9 As shown in the above, the inner peripheral surface of the tip diameter-increased tube portion 5 and the outer peripheral surface of the connecting cylinder portion 41 of the joint body 40 are sealed in a state of mutually biting (crimping) as metal, and external leakage of fluid is prevented.

[0073] In other words, the fluid sealing state of the tip diameter-increased tube portion 5 of the pipe P and the connecting cylinder portion 41 of the joint body 40 can be maintained by the diameter-reducing biasing force (elastic biasing force) in the radial direction inward direction of the metal ring 25.

[0074] As is apparent from Figure 6-Figure 9 As is apparent, in the pipe joint configuration according to the present application, a rubber or synthetic resin sealing member such as an O-ring for sealing is completely omitted. That is, the constituent parts are metal. If specific examples are cited, the pipe P is Cu or Al or stainless steel or the like, the joint body 40 is brass, the cap nut 15 is brass, and the ring 25 is hard Al or stainless steel or the like.

[0075] Next, in order to give a large elastic biasing force in the diameter-reducing direction to the tip diameter-increased tube portion 5 of the pipe P by the ring 25, if the wall thickness dimension T 25 of the ring 25 is compared with the wall thickness dimension T p of the pipe P, it is desirable to be sufficiently large.

[0076] That is, in the other embodiment shown in Figure 10 and Figure 11 , it is shown that (compared with the embodiment of Figure 6-Figure 9 ) the wall thickness dimension T 25 of the ring 25 can be set large.

[0077] If Figure 10 and Figure 11 are compared with the already set Figure 6-Figure 9 , as becomes apparent, the outer diameter dimension of the male screw portion 37 and the bulging portion 39 of the joint body 40 is set sufficiently large, the shape / size of the connecting cylinder portion 41 is left as is, and thus the outer diameter dimension of the stepped portion 38 can be set sufficiently large. That is, the step dimension ΔD can be made sufficiently large.

[0078] In the cap nut 15, its radial direction dimension is increased. That is, the female screw portion 15A and the medium diameter portion 15C of the cap nut 15 are set large, and the outer diameter dimension can be greatly increased. The reason for this is because Figures 6-11 the joint body 40 shown in is a new shape that is not related to the JIS standard, and the above radial direction dimension can be increased.

[0079] Figure 6-Figure 9 and Figure 10、 Figure 11 In the embodiment shown in FIG, the step size ΔD is large enough so that the wall thickness size T of the ring 25 is 25 It can also be set larger (proportionally). 25 The ring 25 can impart a large elastic biasing force in the diameter-reducing direction to the distal expanded tube portion 5 of the catheter P.

[0080] For example, it can be set so that the following equation 3 holds true.

[0081] 1.2･T p ≦T 25 ≦3.0･T p (Formula 3)

[0082] Furthermore, it is ideal to set it as shown in the following formula 4.

[0083] 1.4･T p ≦T 25 ≦2.8･T p (Formula 4)

[0084] In addition, in T 25 When the pressure is lower than the lower limit, the extrusion force in the radial direction is slightly too small, and the sealing performance is slightly insufficient. On the contrary, if the upper limit is exceeded, it is difficult to screw the ring 25 from the cap nut 15 by screwing the cap nut 15. Figure 8 Towards Figure 9 state or from the following Figure 11 Towards Figure 10 The state of chimera.

[0085] exist Figure 10 and Figure 11 In the embodiment shown in FIG, as shown in the above equations 3 and 4, the wall thickness dimension T is increased. 25 , so that the catheter has great resistance to pull-out force and maintains extremely high sealing performance.

[0086] In the present invention, it is a fundamental structural requirement to provide the distal end enlarged diameter tube portion 5 in the connected catheter P. Therefore, the distal end enlarged diameter tube portion 5 will be described below.

[0087] like Figure 12 As shown in FIG. 1 , the tip of the pipe P0 to be processed is inserted into the hole 26A of the split metal mold 26, and the enlarged diameter piece 27, which is divided into four (or more) pieces and has a fan-shaped cross section, is inserted into the pipe P0 to a predetermined depth. If the tapered male metal mold 28 is pressed into the tapered hole 29 formed by the divided enlarged diameter piece 27 in the direction of arrow E, the pipe P0 is Figure 12 As shown in (A) to (B), the diameter-expanding piece 27 is moved in the radially outward direction R, and the distal end diameter-expanded tube portion 5 is formed (processed).

[0088] Furthermore, in order to form the tapered step portion 10 , the diameter-expanding piece 27 is provided with a tapered portion 27A, and the hole portion 26A of the die 26 is provided with a tapered portion 26B.

[0089] After that, if the metal mold 26 is split along the diameter expansion direction and the processed conduit P0 is drawn, the following Figures 1-6 and Figures 8-11 The connected catheter P having the distal end enlarged diameter tube portion 5 is shown in FIG.

[0090] All along, Figure 12 The manual expansion tool shown in FIG is well known. The reason is that, since Figure 13 The brazing pipe connection 63 shown in FIG. 1 is used as a refrigerant pipe or a household hot water (water) supply pipe. That is, in order to perform the brazing pipe connection 63 that has been implemented, it is necessary to pre-process a conduit 61. Figures 1-6 and Figures 8-11 (In addition, the other conduit 62 is inserted into the expanded diameter tube portion 5 without being processed, and the interlocking surface portions X5 are brazed.)

[0091] Thus, the present inventors have focused on the expansion tool widely used in the brazing of pipe connections and the distal end expanded pipe portion that can be easily processed by the expansion tool, and have proposed a pipe joint structure that makes it possible to Figures 1-11 The combination of the individual shapes and structures shown in FIG can be safely operated without using heat such as brazing, and is different from the conventional examples. Figure 14 In comparison, it does not have ultra-precise biting claws 80 and the like, and is also excellent in catheter connection operability.

[0092] As described in detail above, the present application is configured such that two pipes to be connected P are connected to each other from the tip surface 3 to a predetermined axial dimension L5, a tip flared pipe portion 5 is formed in the tip end flared pipe portion 5 of the pipe P, a tapered step portion 10 is formed at the boundary between the tip end flared pipe portion 5 and a base diameter pipe portion 6, an inner core 30 having a connection cylinder portion 31 inserted into the tip end flared pipe portion 5 of the pipe P and an inclined surface 32 abutting against the tip end tapered flared portion 20B is provided, a closure ring-shaped ring 25 fitted into the tip end flared pipe portion 5 through the tapered step portion 10 of the pipe P is provided inside the cap nut 15, the sealing state of the tip end flared pipe portion 5 of the pipe P and the connection cylinder portion 31 of the inner core 30 is maintained by the diameter-reducing biasing force of the ring 25 in the radial inner direction, further, the axial force generated by the threaded engagement of the cap nut 15 into the flared joint body 20 is transmitted to the inner core 30 via the ring 25, the press-sealing state of the tip end tapered flared portion 20B of the flared joint body 20 and the inclined surface 32 of the inner core 30 is maintained, and thus the durability of the sealing member to the sealed fluid is not taken into consideration, and excellent sealing performance is exhibited over a long period of time. In addition, the quality deviation problem caused by flaring processing at the operation site is solved, the part having an extremely super-precise claw 80 (see Figure 14 、 Figure 15 ) can be omitted, and strong pull-out resistance is exhibited. In a severe use environment in which a large temperature difference and high pressure act, high sealing performance can be stably maintained over a long period of time. In a pipe for conveying fluid, as a pipe joint of a coupling type pipe joint in which pipes P are connected one after another, a great contribution is made to the field, and even if a large temperature difference of -70°C to +150°C and high pressure act, strong pull-out resistance and high sealing performance can be stably maintained.

[0093] In addition, a plurality of independent small protrusions 36 having a triangular or Fuji mountain-shaped cross section are formed on the outer peripheral surface of the connection cylinder portion 31 of the inner core 30, and thus reliably and sufficiently deeply bite into the inner peripheral surface of the tip end flared pipe portion 5 of the metal pipe P, and large pull-out resistance and high sealing performance can be exhibited with respect to various sealed fluids.

[0094] In addition, the present invention is configured as follows: a joint body 40 is provided with a male thread portion 37, a step portion 38 and a pipe connecting cylinder portion 41 formed in sequence on both sides in the axial direction; and two cap nuts 15 are provided with a female thread portion 15A threadedly engaged with the male thread portion 37. The two connected pipes P are formed with a top end expanded diameter pipe portion 5 from the top end surface 3 over a predetermined axial center dimension L5, and a tapered step portion 10 is formed at the boundary between the top end expanded diameter pipe portion 5 and the base diameter pipe portion 6. The pipe connecting cylinder portion 41 of the joint body 40 is inserted into the pipe connecting cylinder portion 41. When inserted into the expanded tube portion 5 of the catheter P, the cap nut 15 is screwed into the connector body 40. A closed annular ring 25, which passes through the tapered step 10 of the catheter P and is externally fitted to the expanded tube portion 5, is positioned within the cap nut 15. The radially inward biasing force of the ring 25 maintains the seal between the expanded tube portion 5 of the catheter P and the catheter connecting tube 41 of the connector body 40. This eliminates concerns about the durability of the seal against the sealed fluid and ensures excellent long-term sealing performance. In particular, the number of parts is reduced, resulting in a compact and simplified structure. Furthermore, by completely omitting the pressure-bonded sealing portion between the tapered surfaces (reducing the number of areas required to seal against external leakage by half), further improving sealing performance.

[0095] Furthermore, the problem of quality deviation caused by the expansion process at the operation site can be solved, and the extremely high-precision claw 80 (see Figure 14 、 Figure 15 ) parts, demonstrating strong pull-out resistance. For example, in harsh operating environments such as those with large temperature differences and high pressure, the strong pressure bonding between metals alone can stably achieve high sealing performance over a long period of time.

[0096] Furthermore, the outer circumference of the conduit connecting tube portion 41, which protrudes from the fitting body 40, is formed with a plurality of independent small protrusions 36 having a triangular or Mount Fuji-shaped cross-section. These protrusions reliably and deeply penetrate the inner circumference of the expanded distal end portion 5 of the metal conduit P, thereby providing high pullout resistance and sealing performance for the sealed fluid. Furthermore, the only area of ​​potential fluid leakage between the fitting body 40 and the conduit P is the connecting tube portion 41, where these independent small protrusions 36 are formed. Therefore, the pipe fitting as a whole maintains extremely high sealing performance.

[0097] Furthermore, the union-type pipe joint structure completely omits sealing parts, making all components metal. This allows for stable sealing performance and exceptional durability even in extremely harsh operating environments, ranging from ultra-low temperatures (-70°C) to ultra-high temperatures (+150°C).

[0098] In addition, if the wall thickness of the closed annular ring 25 is T 25 , and the wall thickness of the above-mentioned pipe P is set to T p , the size is set to 1.0･T p ≦T 25 ≦2.5･T p Therefore, a strong elastic shrinking biasing force is generated on the metal ring 25 in the radially inward direction, which can press the metal conduit P against the connecting tube 31 (41) with sufficient strength. Moreover, even under large temperature fluctuations from low temperature to high temperature, high sealing performance is stably exhibited and durability is excellent.

[0099] Explanation of symbols

[0100] 3 Top face

[0101] 5. Top diameter expansion tube

[0102] 6 Basic diameter pipe

[0103] 10 tapered step

[0104] 15 Cap nut

[0105] 15A female thread

[0106] 20 Flare fitting body

[0107] 20A male thread

[0108] 20B Top taper

[0109] 25 closed donut ring

[0110] 30 inner core

[0111] 31 Connecting tube

[0112] 32 Inclined surface

[0113] 36 independent small protrusions

[0114] 37 Male thread

[0115] 38 steps

[0116] 40 Connector body

[0117] 41 Connecting tube

[0118] P catheter

[0119] L5 established axis size

[0120] T 25 Ring wall thickness

[0121] Tp The wall thickness of the conduit.

Claims

1. A pipe joint structure, characterized in that: It is composed of A flared joint body (20) having a male threaded portion (20A) and a top diameter-reducing portion (20B) on both sides in the axial direction, and a cap nut (15) having a female threaded portion (15A) threadedly engaged with the male threaded portion (20A). The two connected conduits (P) are formed with a top diameter expansion tube portion (5) by processing from the top end surface (3) to a predetermined axial center size (L5), and a tapered step portion (10) is formed at the boundary between the top diameter expansion tube portion (5) and the base diameter tube portion (6). The invention is provided with an inner core (30), which comprises a connecting tube portion (31) inserted into the top diameter expansion tube portion (5) of the catheter (P), an inclined surface (32) abutting against the top diameter reduction tapering portion (20B), and a thick-walled large-diameter portion (34) provided between the connecting tube portion (31) and the inclined surface (32) in the axial direction, and a stepped portion (35) is formed between the thick-walled large-diameter portion (34) and the connecting tube portion (31). The cap nut (15) is screwed into the thread of the flared joint body (20), and a closed annular ring (25) which passes through the tapered stepped portion (10) of the conduit (P) and is externally embedded in the top expanded diameter pipe portion (5) is arranged inside the cap nut (15). The sealing state between the top expanded diameter tube portion (5) of the catheter (P) and the connecting cylindrical portion (31) of the inner core (30) is maintained by utilizing the radially inwardly reducing biasing force of the ring (25). Furthermore, the axial force generated by the threaded engagement of the cap nut (15) with the flared joint body (20) is transmitted to the inner core (30) via the ring (25), thereby maintaining the press-fit sealing state between the top end tapered portion (20B) of the flared joint body (20) and the inclined surface (32) of the inner core (30). Completely omitting sealing parts, making all components metal, The cap nut (15) has an axially orthogonal surface inner surface (17A) at the top position, against which the top surface of the closed annular ring (25) abuts along the axial direction, and the closed annular ring (25) is sandwiched between the step portion (35) and the axially orthogonal surface inner surface (17A) in the axial direction.

2. The pipe joint structure according to claim 1, wherein: A plurality of independent small protrusions (36) with triangular or Mount Fuji-shaped cross sections are formed on the outer peripheral surface of the connecting tube portion (31) of the inner core (30).

3. A pipe joint structure, characterized in that: It is composed of A connector body (40) having a male threaded portion (37), a stepped portion (38) and a conduit connecting tube portion (41) formed in sequence on both sides in the axial direction, and two cap nuts (15) having a female threaded portion (15A) threadedly engaged with the male threaded portion (37). The two connected conduits (P) are formed with a top diameter expansion tube portion (5) by processing from the top end surface (3) to a predetermined axial center size (L5), and a tapered step portion (10) is formed at the boundary between the top diameter expansion tube portion (5) and the base diameter tube portion (6). In a state where the catheter connecting tube portion (41) of the connector body (40) is inserted into the top diameter enlarged tube portion (5) of the catheter (P), the cap nut (15) is screwed into the thread of the connector body (40), and a closed annular ring (25) that passes through the tapered step portion (10) of the catheter (P) and is externally fitted into the top diameter enlarged tube portion (5) is arranged inside the cap nut (15). The radially inward reducing biasing force of the ring (25) is used to maintain the sealing state between the top expanded diameter tube portion (5) of the catheter (P) and the catheter connecting cylinder portion (41) of the joint body (40). The sealing member is completely omitted so that all components are made of metal. The cap nut (15) has an inner surface orthogonal to the axis at the top position, against which the top surface of the closed annular ring (25) abuts in the axial direction. The closed annular ring (25) is sandwiched between the step portion (38) and the inner surface orthogonal to the axis in the axial direction.

4. The pipe joint structure according to claim 3, wherein: A plurality of independent small protrusions (36) having a triangular or Mount Fuji-shaped cross section are formed on the outer peripheral surface of the conduit connecting cylinder (41) protruding from the joint body (40).

5. The pipe joint structure according to claim 1, 2, 3 or 4, wherein: If the wall thickness of the closed annular ring (25) is set to (T 25 ), and the wall thickness of the conduit (P) is set to (T p ), then the size setting is Equation 1, 1.0·T p ≦T 25 ≦2.5·T p (Formula 1).

Images