JP2021099132A - Pipe joint structure for refrigerant - Google Patents

Abstract

To provide a pipe joint structure that has excellent sealing performance and a large anti-drawing force, can support a significant temperature fluctuation of refrigerant and has a long life.SOLUTION: A pipe joint structure for refrigerant includes a flare joint body 20 and a box nut 15. A pipe to be connected P is formed with a tip diameter enlarged pipe part 5 across a specified shaft center dimension from a tip surface 3. A closed annular ring 25 is externally fitted to the tip diameter enlarged pipe part 5 beyond a tapered-stepped part 10 of the pipe P and connected thereto by being applied with a squeezing force so as to come into pressure-contact with a connection cylinder part 31 of an in-core 30.SELECTED DRAWING: Figure 3

Description

The present invention relates to a pipe joint structure for a refrigerant.

Conventionally, the flare joint shown in FIG. 11 is widely known. Generally, as shown in FIG. 11, this flared joint is formed by plastic working a flared portion f at the end of a pipe P with a work tool (jig). It is applied to the tapered portion a of the flare joint body h and tightened with a cap nut n, and is pressed by the tapered surface t of the cap nut n and the tapered portion a of the flare joint body h to ensure sealing by mutual pressure welding of metal surfaces. (See, for example, Patent Document 1). At the work site, when the flare processing portion f is formed at the end of the connected pipe P using a special jig (work tool), the flare processing portion f is formed due to a large plastic deformation in a tapered shape. easy to crack the small-diameter side corner portion f _1. In particular, when the material of the pipe P is Al, the crack generation rate is high. In addition, there is a problem that quality variation is likely to occur due to flaring at the work site (whether the pipe P is Cu or Al).
Therefore, a pipe joint structure having a structure as shown in FIGS. 9 and 10 has been proposed (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2005-42858 Japanese Unexamined Patent Publication No. 2010-270846

The pipe joint structure shown in FIGS. 9 and 10 has a flare joint body 82 and a cap nut 83, and has a pull-out prevention member 81 inside, and flare processing and other processing are omitted at the pipe tip. Although it has the advantage of being able to do so, it required an extremely precise pull-out prevention member 81 having a claw 80. Therefore, there remains a problem that it is difficult to manufacture and the cost is high. Further, when a rotational torque acts on the pipe P, the pipe may be pulled out while the spiral groove is formed by the claw 80.
Further, the pipe joint structures of FIGS. 9 and 10 require sealing materials such as (plural) O-rings 84 and 85. With this rubber O-ring 84, 85 or the like, it is difficult for the operating temperature to withstand a large temperature change of -50 ° C to + 130 ° C, and problems remain in terms of durability and sealing performance. There is.

Therefore, the present invention provides a pipe joint structure that solves such a problem, can omit ultra-precision parts, is easy to manufacture, can reduce costs, is compact, and can perform stable and easy connection work. The purpose is to do. In particular, for refrigerant piping, another object is to provide a suitable pipe joint structure that can sufficiently withstand severe temperature changes and has a long life.

Therefore, the present invention includes a flare joint body having a male threaded portion and a tapered tip diameter portion, and a cap nut having a female threaded portion screwed to the male threaded portion, and the pipe to be connected has a tip. A tip diameter-expanded pipe portion is formed from the surface over a predetermined axial dimension, and a tapered stepped portion is formed at the boundary between the tip diameter-expanded pipe portion and the basic diameter pipe portion. A connection cylinder portion inserted into the tip diameter expansion pipe portion and an incore having a slope surface that abuts on the tip diameter reduction taper portion are provided, and the tapered step of the pipe is provided by screwing the bag nut to the flare joint body. A closed annular ring that is externally fitted to the tip diameter-expanding pipe portion via the attachment portion is provided inside the bag nut, and the tip diameter of the pipe is expanded by the radial inward reducing urging force of the ring. The sealed state between the pipe portion and the connecting cylinder portion of the in-core is maintained, and the axial force accompanying the screwing of the bag nut to the flare joint body is transmitted to the in-core via the ring to cause the flare. It is configured to maintain a pressure-welded sealed state between the tapered tip diameter of the joint body and the sloped surface of the in-core.

Further, on the outer peripheral surface of the connecting cylinder portion of the in-core, a plurality of independent small ridges having a triangular cross section or a mountain-shaped cross section are formed.
In addition, the sealing material for sealing was completely omitted, and all the components were made of metal.
Further, when the wall thickness dimension of the closed circular ring ring is T ₂₅ and the wall thickness dimension of the pipe is T _p , the dimension is set so that Equation 1 holds.
1.0 ・ T _p ≦ T ₂₅ ≦ 2.5 ・ T _p (Formula 1)

According to the present invention, ultra-precision parts can be omitted and the pipe can be manufactured relatively easily, and a strong pull-out force can be imparted to the pipe. Rubber sealing materials such as O-rings can be omitted, and it can withstand temperature changes from extremely low temperature to ultra-high temperature ─── for example, -50 ℃ to + 130 ℃ ───, and also has sufficient pull-out resistance of the pipe. Can be kept large.
Even if it is necessary to pre-process the tip diameter expansion pipe part at the pipe end, if you use a work tool (jig) that has been used for brazing for a long time, skill is required easily and surely. Can be processed without. Due to the presence of the tip diameter-expanded pipe portion, the inner diameter dimension of the flow path hole becomes equal to the inner diameter dimension of the pipe itself, and an increase in fluid passage resistance can be suppressed.

It is sectional drawing of the connection work in progress state which shows one Embodiment of this invention. It is sectional drawing which shows the state in the middle of connection after that. It is sectional drawing which shows the connection completion state. It is sectional drawing of the connection work in progress state which shows the other embodiment of this invention. It is sectional drawing which shows the state in the middle of connection after that. It is sectional drawing which shows the connection completion state. It is sectional drawing explaining the main part of the work tool for forming the tip diameter expansion pipe part, and the diameter expansion method. It is sectional drawing for demonstrating the brazing work which has been carried out from ancient times to the present, and demonstrating the end part of the brazed pipe. A conventional example is shown, and it is a cross-sectional view of a state in the middle of connection work. It is sectional drawing of the connection completion state which shows the conventional example. It is sectional drawing which shows the other conventional example.

Hereinafter, the present invention will be described in detail based on the illustrated embodiments.
In one embodiment of the present invention shown in FIGS. 1, 2 and 3, the connected pipe P has a tip diameter-expanded pipe portion 5 formed _{from the tip surface 3 over a predetermined axial dimension L 5.} ing.
A tapered stepped portion 10 is formed at the boundary between the tip diameter-expanded pipe portion 5 and the basic diameter _{pipe portion 6 having the original basic diameter D 0 of the pipe.}

Reference numeral 20 denotes a flare joint main body, which has a male threaded portion 20A and a tip diameter reduced taper portion 20B, and corresponds to a flare pipe joint specified in JIS B 8607, which is the same as the flare joint main body h shown in FIG. belongs to.
Reference numeral 15 denotes a cap nut, which has a female threaded portion 15A screwed to the male threaded portion 20A of the flare joint body 20.
A large-diameter female screw portion 15A, a medium-diameter portion 15C, and a tip small-diameter portion 15F are sequentially formed in the hole portion 16 of the cap nut 15 from the base end to the tip end.
As described above, the refrigerant pipe joint structure according to the present invention has a flare joint body 20 having a male threaded portion 20A and a tip diameter reduction tapered portion 20B, and a female threaded portion 15A screwed to the male threaded portion 20A. It is equipped with a cap nut 15.

In the connected state, reference numeral 30 denotes an in-core contained in the cap nut 15 as shown in FIG. 3, and the in-core 30 is a connecting cylinder portion 31 inserted in the tip diameter-expanded pipe portion 5 of the pipe P. The joint body 20 is provided with a gradient surface 32 that abuts on the tip diameter reduced tapered portion 20B.
More specifically, the in-core 30 has a through hole 33 along the axis, and the gradient surface 32 is formed on the proximal end side of the through hole 33 and has a diameter-expanding taper shape in the proximal end direction. It is also desirable to make it slightly convex (convex rounded). Further, the base end portion of the in-core 30 is a wall-thick large-diameter portion 34 having a diameter larger than that of the connection cylinder portion 31, and between the thick-walled large-diameter portion 34 and the (small-diameter) connection cylinder portion 31, The stepped portion 35 is formed.

Further, on the outer peripheral surface of the connecting cylinder portion 31 of the in-core 30, a plurality of independent small ridges 36 having a triangular cross section or a Mt. Fuji shape are formed.
Reference numeral 25 denotes a closed circular ring, which is composed of a short cylinder. As shown in FIG. 1, the ring 25 is fitted externally to the pipe P in a loose-fitting shape before the forming of the tip diameter-expanded pipe portion 5, and then the tip is fitted as shown in FIG. 7 (described later). When the diameter-expanded pipe portion 5 is formed, the ring 25 hits the tapered stepped portion 10 and does not separate from the tip side of the pipe P (to the left in FIG. 1).

As shown in FIGS. 1 to 2, when the cap nut 15 is lightly moved to the left (by hand), the ring 25 fits 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 tip position (a small diameter portion 15F is formed on the inner peripheral surface of the inner flange portion 17), and the axial center orthogonal plane of the inner flange portion 17 is formed. The inner surface 17A and the tip surface of the ring 25 come into contact with each other (see FIGS. 2 and 3).

As shown in FIGS. 1 to 2, when the cap nut 15 is brought close to the joint body 20 and then the cap nut 15 is screwed into the male screw portion 20A of the joint body 20, the ring 25 inside the cap nut 15 is formed. Is pressed in the axial inward direction on the inner surface 17A of the inner flange portion 17, gradually moves toward the tip of the pipe, and comes into contact with the tapered stepped portion 10 of the pipe P.

The inner diameter dimension of the ring 25 is set smaller than the outer diameter dimension of the tip enlarged diameter pipe portion 5 of the pipe P in the free state. As a result, if the cap nut 15 is continuously screwed, the ring 25 is fitted onto the tip diameter-expanded pipe portion 5 via the tapered stepped portion 10 of the pipe P, as shown in FIGS. 2 to 3. Moreover, a large force (squeezing force) is applied in the diameter reduction direction, and the independent small ridge 36 bites into the inner peripheral surface of the tip diameter expanding pipe portion 5, and the tip is expanded as shown in FIG. The inner peripheral surface of the diameter pipe portion 5 and the outer peripheral surface of the connecting cylinder portion 31 of the in-core 30 are sealed as a metal-to-metal biting state (pressure contact state) to prevent the refrigerant from leaking to the outside.

In other words, the refrigerant is sealed between the expanded pipe portion 5 at the tip of the pipe P and the connecting cylinder portion 31 of the in-core 30 by the radial inwardly contracted urging force (elastic urging force) of the metal ring 25. Can be kept.
Further, the force in the axial direction due to the screwing of the cap nut 15 to the flare joint body 20 is transmitted to the in-core 30 via the ring 25, and the tip diameter reduced tapered portion 20B of the flare joint body 20 and the tapered portion 20B. The in-core 30 can be kept in a pressure-welded sealed state with the slope surface 32 (see FIGS. 1 to 2).

As is clear from FIGS. 1 to 3, in the refrigerant pipe joint structure according to the present invention, a rubber or synthetic resin sealing material such as an O-ring for sealing is completely omitted. That is, the components are made of metal. To give a specific example, the pipe P is Cu or Al, the flare joint body 20 is brass, the cap nut 15 is brass, the incore 30 is brass or stainless steel, and the ring 25 is hard Al or stainless steel.

Next, the resiliently urging force of the ring 25 is large diameter direction, in order to impart to the tip enlarged tube portion 5 of the pipe P, the thickness dimension T _p of the pipe P to the thickness dimension T ₂₅ of the ring 25 It is desirable to make it sufficiently large compared to.
For example, it is preferable to set so that the following formula 1 is satisfied.
1.0 ・ T _p ≦ T ₂₅ ≦ 2.5 ・ T _p (Formula 1)
Even more desirable is the setting as shown in Equation 2 below.
1.2 ・ T _p ≦ T ₂₅ ≦ 2.2 ・ T _p (Formula 2)

If T ₂₅ is less than the lower limit, the squeezing force in the radial inward direction becomes too small and the sealing performance becomes insufficient. On the contrary, when the upper limit is exceeded, it becomes difficult to fit the ring 25 to the state of FIGS. 2 to 3 or the state of FIGS. 5 to 6 described later due to the screwing of the cap nut 15. Become.

Next, other embodiments shown in FIGS. 4 to 6 will be described.
In FIGS. 4 to 6, within the range of the above-mentioned formula 1, the wall thickness dimension T ₂₅ of the ring 25 is a large value, and the ring outer diameter dimension D ₂₅ is the inner diameter dimension of the female screw portion 15A of the cap nut 15. The case where it is larger than _{D 15 is shown.} Since the ring 25 cannot be inserted into the cap nut 15 from the front side (female screw portion 15A side) as shown in FIGS. 1 and 2, the ring 25 can be inserted from the rear of the cap nut 15 (right side of FIGS. 4 to 6). The structure for inserting 25 into the cap nut 15 is shown.

That is, on the rear end side of the cap nut 15, a large diameter portion 19 and a reverse screw portion 22 are formed in the latter half portion of the hole portion 16 along the axial center via the stepped portion 18.
Further, a ring holding ring 23 is attached. That is, it has a recessed portion 24 for fitting the ring 25, and the ring 25 is fitted into the recessed recessed portion 24 so that the outer circumference of the ring holding ring 23 is reversed with respect to the reverse screw portion 22 of the cap nut 15. If the screw portion 7 is screwed into the state shown in FIGS. 4 to 5, the state is the same as in FIG. That is, the inwardly angular portion of the ring 25 comes into contact with the tapered stepped portion 10 of the pipe P.

After that, as shown in FIGS. 5 to 6, if the cap nut 15 is screwed, the ring 25 is fitted so as to ride on the diameter-expanded pipe portion 5, and the elastic contraction force of the ring 25 is obtained. As a result, the independent small ridges 36 bite into the inner surface of the enlarged diameter pipe portion 5 of the pipe P, exhibit the pull-out resistance of the pipe P, and can be in a sealed state (with respect to the refrigerant).
In the assembled state of the cap nut 15 and the ring holding ring 23 as shown in FIGS. 5 and 6, the inner collar portion 17 shown in FIGS. 1 to 3 is formed on the side of the ring holding ring 23. , Can be said.

As described above, in the embodiment shown in FIGS. 4 to 6, the wall thickness dimension T ₂₅ of the ring 25 is sufficiently larger than the embodiment shown in FIGS. 1 to 3, so that the connection is completed in FIG. The pipe pull-out resistance is large, and the sealing performance can be maintained extremely high.

In the present invention, it is a basic configuration requirement that the tip diameter-expanded pipe portion 5 is provided in the connected pipe P. Therefore, the tip diameter expanding tube portion 5 will be described below.
As shown in FIG. 7, _{the tip of the pipe P 0 to} be machined is inserted into the hole 26A of the split die 26, and the cross-section fan-shaped enlarged diameter piece 27 divided into four (or more) is inserted into the pipe P. Insert to a predetermined depth with respect to _0. When the tapered male mold 28 is pushed into the tapered hole portion 29 formed by the divided diameter-expanding pieces 27 in the direction of arrow E, the diameter-expanding pieces 27 are as shown in FIGS. 7A to 7B. Moves in the radial outward direction R, and the tip diameter expanding tube portion 5 is formed (processed).

In order to form the tapered stepped portion 10, the enlarged diameter piece 27 is provided with the tapered portion 27A, and the hole portion 26A of the mold 26 is provided with the tapered portion 26B.
After that, the mold 26 is divided and operated in the diameter expansion direction, and the processed pipe P ₀ is pulled out to manufacture a connected pipe P with a tip diameter expansion pipe portion 5 as shown in FIGS. 1 to 6 and the like. Will be done.
Since ancient times, the manual work tool for diameter expansion shown in FIG. 7 has been widely known. The reason is that the brazed pipe connection 63 as shown in FIG. 8 has been used for a refrigerant pipe and a household hot water supply (water) pipe for a long time. That is, because of the brazing pipe connection 63 that has been practiced for a long time, it is necessary to pre-process the tip diameter-expanded pipe portion 5 shown in FIGS. 1 to 6 for one of the pipes 61. (The other pipe 62 is inserted into the enlarged diameter pipe portion 5 as it is without being processed, and the mutual fitting surface portion X ₅ is brazed.)
In this way, the present inventor focused on the diameter-expanding work tool widely used for pipe connection work by brazing and the tip-diameter-expanded pipe portion that can be easily machined by the tool, and FIGS. 1 to 6 show. By combining the unique shape and structure as shown, it is possible to work safely without using heat such as brazing, and it does not have an ultra-precision biting claw 80 or the like as compared with FIG. 9 of the conventional example. Here, we propose a pipe joint structure that is excellent in pipe connection workability.

As described in detail above, the present invention includes a flare joint body 20 having a male screw portion 20A and a tip diameter reduction taper portion 20B, and a bag nut 15 having a female screw portion 15A screwed to the male screw portion 20A. In the connected pipe P, the tip diameter-expanded pipe portion 5 is formed from the tip surface 3 over a predetermined axial dimension L ₅ , and the tip diameter-expanded pipe portion 5 and the basic diameter pipe portion 6 are formed. A tapered stepped portion 10 is formed at the boundary of the pipe P, and a connecting cylinder portion 31 inserted into the tip diameter-expanded pipe portion 5 of the pipe P and a gradient surface 32 that abuts on the tip diameter-reduced tapered portion 20B are formed. A closed circular annular ring 25 having an in-core 30 and being externally fitted to the tip expansion pipe portion 5 via the tapered stepped portion 10 of the pipe P by screwing the bag nut 15 to the flare joint body 20. Is provided inside the bag nut 15, and the tip diameter-expanded pipe portion 5 of the pipe P and the connecting cylinder portion 31 of the in-core 30 are sealed by the radial inward reducing urging force of the ring 25. Further, the force in the axial direction accompanying the screwing of the bag nut 15 to the flare joint body 20 is transmitted to the in-core 30 via the ring 25, and the tip diameter-reduced tapered portion of the flare joint body 20 is transmitted. Since the 20B and the slope surface 32 of the in-core 30 are configured to be pressure-welded and sealed, excellent sealing performance is exhibited for a long period of time without worrying about the durability of the sealing material against the refrigerant. In addition, the problem of quality variation due to flaring at the work site is solved, parts with extremely precise claws 80 (see FIGS. 9 and 10) can be omitted, and strong pull-out resistance is exhibited. Refrigerant piping has an extremely large temperature difference of -50 ° C to + 130 ° C, and it is possible to stably maintain high sealing performance for a long period of time in a harsh usage environment where high pressure acts. became.

Further, since a plurality of independent small ridges 36 having a triangular cross section or a Mt. Fuji shape are formed on the outer peripheral surface of the connecting cylinder portion 31 of the incore 30, the tip diameter expanding pipe portion 5 of the metal pipe P is included. It surely bites deep enough into the peripheral surface, and can exhibit a large pull-out resistance and high sealing performance with respect to the refrigerant.

In addition, since the sealing material for sealing is completely omitted and all the components are made of metal, stable sealing is performed under extremely harsh usage environments from ultra-low temperature (-50 ° C) to ultra-high temperature (+ 130 ° C). Performance can be demonstrated over a long period of use.

Further, if the wall thickness dimension of the closed circular ring ring 25 is T ₂₅ and the wall thickness dimension of the pipe P is T _p , 1.0 · T _p ≦ T ₂₅ ≦ 2.5 · T _p is established. Since the dimensions are set as described above, a strong elastic contraction diameter urging force of the metal ring 25 is generated toward the radial inward direction, and the metal pipe P is sufficiently strong with respect to the connecting cylinder portion 31 of the in-core 30. It can be crimped, and even with large temperature fluctuations from low temperature to high temperature, it stably exhibits high sealing performance to the refrigerant and has excellent durability.

3 Tip surface 5 Tip diameter expansion tube 6 Basic diameter tube
10 Tapered stepped part
15 cap nut
15A female thread
20 Flare fitting body
20A male screw part
20B Tip diameter taper
25 Closed circular ring
30 incore
31 Connection tube
32 Gradient surface
36 Independent small ridge P pipe L ₅ Predetermined axis dimension T ₂₅ Ring wall thickness T _p Pipe wall thickness

Claims (4)

A flared joint body (20) having a male threaded portion (20A) and a tapered tip diameter portion (20B), and a cap nut (15) having a female threaded portion (15A) screwed onto the male threaded portion (20A). And prepare
In the connected pipe (P), a tip diameter-expanded pipe portion (5) is formed from the tip surface (3) to a predetermined axial dimension (L ₅ ), and the tip diameter-expanded pipe portion (5) and the above-mentioned tip diameter-expanded pipe portion (5) are formed. A tapered stepped portion (10) is formed at the boundary with the basic diameter pipe portion (6).
An in-core (30) having a connecting cylinder portion (31) inserted into the tip diameter-expanded pipe portion (5) of the pipe (P) and a gradient surface (32) that abuts on the tip diameter-reduced tapered portion (20B). With
By screwing the cap nut (15) to the flare joint body (20), the cap nut (15) is externally fitted to the tip diameter-expanded pipe portion (5) via the tapered stepped portion (10) of the pipe (P). An annular ring (25) is provided inside the cap nut (15).
With the radial inward contraction force of the ring (25), the tip diameter expanding pipe portion (5) of the pipe (P) and the connecting cylinder portion (31) of the incore (30) are sealed. Keep,
Further, the force in the axial direction accompanying the screwing of the cap nut (15) to the flare joint body (20) is transmitted to the in-core (30) via the ring (25), and the flare joint body (20) is transmitted. ), A pipe joint structure for a refrigerant, characterized in that the tapered portion (20B) at the tip of the tip and the slope surface (32) of the in-core (30) are kept in a pressure-welded sealed state. The refrigerant pipe joint structure according to claim 1, wherein a plurality of independent small protrusions (36) having a triangular cross section or a Mt. Fuji shape are formed on the outer peripheral surface of the connecting cylinder portion (31) of the incore (30). The refrigerant pipe joint structure according to claim 1 or 2, wherein the sealing material for sealing is completely omitted, and all the components are made of metal. If the wall thickness dimension of the closed circular ring ring (25) is (T ₂₅ ) and the wall thickness dimension of the pipe (P) is (T _p ), the dimension is set so that Equation 1 holds. Item 2. The refrigerant pipe joint structure according to item 1, 2, or 3.
1.0 ・ T _p ≦ T ₂₅ ≦ 2.5 ・ T _p (Formula 1)

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