JP6678981B1 - Refrigerant pipe joint structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe joint structure having excellent sealing performance, large pull-out resistance, capable of coping with a large temperature fluctuation of a refrigerant, and having a long life. A flared joint main body (20) and a cap nut (15) are provided, and a pipe (P) to be connected has a tip diameter expanding pipe section (5) extending from a tip surface (3) to a predetermined axial center dimension. A closed annular ring 25 is fitted over the tip diameter-expanded pipe portion 5 beyond the tapered stepped portion 10 of the pipe P, and a drawing force is applied so as to come into pressure contact with the connecting tubular portion 31 of the in-core 30, Connected. [Selection diagram] Fig. 3

Description

  The present invention relates to a refrigerant pipe joint structure.

Conventionally, the flare joint shown in FIG. 11 is widely known. In general, this flare joint was formed by plastically working a flared portion f on the end portion of the pipe P with a work tool (jig) as shown in FIG. Apply the taper part a of the flare joint body h and tighten it with the cap nut n, and press between the taper surface t of the cap nut n and the taper part a of the flare joint body h to secure the hermeticity by mutual pressure contact of the metal surfaces. This is a configuration (see, for example, Patent Document 1). At the work site, when the flared portion f is formed on the end portion of the pipe P to be connected by using a dedicated jig (work tool), the flared portion f is largely plastically deformed into a tapered shape. Cracks are likely to occur at the small-diameter side corner f ₁ . In particular, when the material of the pipe P is Al, the crack occurrence rate is high. Further, there is a problem that quality variation easily occurs due to flare processing 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).

JP, 2005-42858, A JP, 2010-270846, A

The pipe joint structure shown in FIGS. 9 and 10 has a flare joint body 82, a cap nut 83, and a pull-out prevention member 81 inside, and neither flaring nor other processing is omitted at the pipe tip. Although there is an advantage in that it is possible, a pull-out prevention member 81 having a claw 80, which is extremely super-precision, is required. Therefore, it remains difficult to manufacture and costly. Further, when the rotating torque acts on the pipe P, the pipe 80 may be pulled out while the spiral groove is formed by the claw 80.
Further, the pipe joint structures shown in FIGS. 9 and 10 require sealing materials such as (a plurality of) O-rings 84 and 85. With this rubber O-ring 84, 85 or other sealing material, it is difficult 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, can be manufactured easily and can reduce the cost, and can be compact and have stable and easy connection work. The purpose is to do. In particular, it is another object to provide a suitable pipe joint structure for a refrigerant pipe, which sufficiently withstands severe temperature changes and has a long life.

  Therefore, the present invention includes a flare joint body having a male screw portion and a taper portion having a reduced diameter tip, and a cap nut having a female screw portion screwed to the male screw portion, and the connected pipe has a tip end. A tip diameter expanding tube portion is formed over a predetermined axial center dimension from the surface, and a tapered step portion is formed at the boundary between the tip diameter expanding tube portion and the basic diameter tube portion, A tapered cylindrical step of the pipe is provided by a connecting cylinder part inserted in the tip diameter expansion tube part and an incore having a sloped surface that abuts the tip diameter reduction taper part, and by screwing the cap nut into the flare joint body. A closed annular ring, which is externally fitted to the tip diameter-expanding pipe portion through the attachment part, is provided inside the cap nut, and the tip end diameter of the pipe is enlarged by a radial diametrically urging force of the ring. Maintaining a sealed state between the pipe portion and the connecting core portion of the incore, and further, the bag The axial force associated with screwing the flare joint body to the flare joint body is transmitted to the in-core via the ring, and the flared joint body has a tapered tip end and the sloped surface of the in-core. It is configured to keep.

Further, on the outer peripheral surface of the connecting cylindrical portion of the in-core, a plurality of small triangular protrusions each having a triangular cross section or a Mt. Fuji cross section are formed.
In addition, the sealing material for sealing was omitted altogether, and all components were made of metal.
When the wall thickness of the closed annular ring is T ₂₅ and the wall thickness of the pipe is T _p , the dimensions are set so that the mathematical expression 1 is satisfied.
1.0 · T _p ≦ T ₂₅ ≦ 2.5 · T _p (Formula 1)

According to the present invention, ultra-precise parts can be omitted and the pipe can be manufactured relatively easily, and a strong pulling resistance can be imparted to the pipe. Rubber seals such as O-rings can be omitted, and it can withstand temperature changes from extremely low to very high temperatures, for example, -50 ° C to + 130 ° C, and has sufficient pull-out resistance for pipes. Can be maintained large.
Even if it is necessary to machine the tip diameter expansion pipe part to the pipe end in advance, using a work tool (jig) that has been used for brazing for a long time, it is simple and reliable, and skill is required. Can be processed without. Due to the presence of the tip diameter expanding 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 state in the middle of the connection work which shows one Embodiment of this invention. It is sectional drawing which shows the connection intermediate state after that. It is sectional drawing which shows a connection completion state. It is sectional drawing of the state in the middle of the connection work which shows other embodiment of this invention. It is sectional drawing which shows the connection intermediate state after that. It is sectional drawing which shows a connection completion state. It is sectional drawing explaining the principal part of the forming tool of a tip diameter expansion pipe part, and the diameter expansion method. It is sectional drawing for demonstrating the brazing work performed from old times to the present, and for demonstrating the brazed pipe end part. FIG. 11 is a cross-sectional view showing a conventional example and in the middle of connection work. It is sectional drawing of the connection completion state which shows a prior art example. It is sectional drawing which shows another prior art example.

Hereinafter, the present invention will be described in detail based on the illustrated embodiments.
In the embodiment of the present invention shown in FIGS. 1, 2 and 3, in the connected pipe P, a tip diameter expanding tube portion 5 is formed from the tip surface 3 to 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 body, which has a male screw portion 20A and a tip diameter reducing taper portion 20B, corresponds to a flare pipe joint specified in JIS B 8607, and is similar to the flare joint body h shown in FIG. belongs to.
A cap nut 15 has a female screw portion 15A screwed to the male screw 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 16 of the cap nut 15 from the base end to the tip.
As described above, the refrigerant pipe joint structure according to the present invention has the flare joint body 20 having the male screw portion 20A and the tip diameter reducing taper portion 20B, and the female screw portion 15A screwed to the male screw portion 20A. It is provided with a cap nut 15.

In the connection completed state, 30 is an in-core internally contained in the cap nut 15 as shown in FIG. 3, and this in-core 30 is connected to the connecting cylinder part 31 inserted in the tip diameter expansion pipe part 5 of the pipe P. The sloped surface 32 that abuts on the taper portion 20B on the tip end of the joint body 20 is provided.
More specifically, the in-core 30 has a through hole 33 along the axial center, and the sloped surface 32 is formed on the base end side of the through hole 33 and has a taper shape that expands in the base end direction. It is also desirable to make it slightly convex (convex radius). In addition, the proximal end portion of the in-core 30 is a thick-walled large-diameter portion 34 having a diameter larger than that of the connecting tubular portion 31, and between the thick-walled large-diameter portion 34 and the (small-diameter) connecting tubular portion 31, A stepped portion 35 is formed.

Further, on the outer peripheral surface of the connection tubular portion 31 of the in-core 30, a plurality of independent small protrusions 36 each having a triangular shape or a Mt. Fuji cross section are formed.
Further, 25 is a closed annular ring, which is composed of a short cylindrical body. As shown in FIG. 1, the ring 25 is externally fitted to the pipe P in a loose fitting manner before forming the tip diameter-expanding tube portion 5, and thereafter, as shown in FIG. When the expanded diameter pipe portion 5 is formed, the ring 25 hits the tapered stepped portion 10 and does not separate toward the tip side of the pipe P (to the left in FIG. 1).

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

  As shown in FIGS. 1 and 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 moved. While being pressed inward in the axial direction by the inner surface 17A of the inner flange portion 17, gradually moves toward the tip end of the pipe and comes into contact with the tapered stepped portion 10 of the pipe P.

  The inner diameter of the ring 25 is set to be smaller than the outer diameter of the tip diameter expanding tube portion 5 of the pipe P in the free state. As a result, when the cap nut 15 is continuously screwed, the ring 25 is externally fitted to the tip diameter-expanded pipe portion 5 via the tapered stepped portion 10 of the pipe P as shown in FIGS. Moreover, a large force (throttle force) is applied in the diameter reducing direction, and the independent small protrusion 36 is bited into the inner peripheral surface of the tip diameter expanding tube portion 5, and as shown in FIG. The inner peripheral surface of the radial pipe portion 5 and the outer peripheral surface of the connecting tubular portion 31 of the in-core 30 are sealed in a state in which they are bite into each other (press contact state), and prevent external leakage of the refrigerant.

In other words, the refrigerant sealing state between the radially enlarged tip portion 5 of the pipe P and the connecting tube portion 31 of the in-core 30 is caused by the radially inwardly reducing radial urging force (elastically urging force) of the metal ring 25. Can be kept.
Further, the axial force associated with screwing the cap nut 15 onto the flare joint body 20 is transmitted to the incore 30 via the ring 25, and the tip diameter reducing taper portion 20B of the flare joint body 20 is provided. It is possible to maintain a pressure-contact sealed state with the inclined surface 32 of the incore 30 (see FIGS. 1 and 2).

  As is apparent from FIGS. 1 to 3, in the refrigerant pipe joint structure according to the present invention, a sealing material made of rubber or synthetic resin such as an O-ring for sealing is completely omitted. That is, the components are made of metal. As 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 as compared with.
For example, it is preferable to set so that the following Expression 1 is established.
1.0 · T _p ≦ T ₂₅ ≦ 2.5 · T _p (Formula 1)
It is more desirable to set as in the following Expression 2.
1.2 · T _p ≦ T ₂₅ ≦ 2.2 · T _p (Formula 2)

If T ₂₅ is less than the lower limit value, the radial inward drawing force becomes too small and the sealing performance becomes insufficient. On the contrary, when the upper limit is exceeded, it is 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, another embodiment shown in FIGS. 4 to 6 will be described.
In FIGS. 4 to 6, within the range of the above-described mathematical expression 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 is inserted from the rear of the cap nut 15 (right side of FIGS. 4 to 6). The structure for inserting 25 into the inside of the cap nut 15 is shown.

That is, in the cap nut 15, the large diameter portion 19 and the reverse threaded portion 22 are formed on the rear end side via the stepped portion 18 in the latter half portion of the hole portion 16 along the axial center.
Further, a ring holding ring 23 is attached. That is, there is a recessed portion 24 into which the ring 25 is fitted, and the ring 25 is fitted into this recessed portion 24 so that the outer periphery of the ring retaining ring 23 is reversed with respect to the reverse threaded portion 22 of the cap nut 15. If the screw portion 7 is screwed to the state shown in FIGS. 4 to 5, the state becomes the same as that of FIG. That is, the inner corner of the ring 25 contacts the tapered stepped portion 10 of the pipe P.

Then, as shown in FIG. 5 to FIG. 6, when the cap nut 15 is screwed, the ring 25 is externally fitted so as to ride on the expanded pipe portion 5, and the elastic contraction force of the ring 25 is applied. As a result, the independent small ridges 36 bite into the inner surface of the expanded pipe portion 5 of the pipe P so that the pulling-out resistance of the pipe P can be exerted and the sealed state (with respect to the refrigerant) can be achieved.
When the cap nut 15 and the ring holding ring 23 are assembled as shown in FIGS. 5 and 6, the inner collar portion 17 shown in FIGS. 1 to 3 is formed on the ring holding ring 23 side. Can say

As described above, in the embodiment shown in FIGS. 4 to 6, since the wall thickness T ₂₅ of the ring ₂₅ is sufficiently larger than that in the embodiment of FIGS. 1 to 3, under the connection completion state of FIG. The pipe has a high pull-out resistance, and the sealing performance can be kept extremely high.

In the present invention, the provision of the tip diameter-expanding pipe portion 5 on the pipe P to be connected is a fundamental constituent requirement. 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 processed is inserted into the hole 26A of the split mold 26, and the expanded piece 27 having a fan-shaped cross section is divided into four (or more) pipes P. Insert to a predetermined depth with respect to ₀ . If the tapered male die 28 is pushed in the direction of the arrow E into the tapered hole portion 29 formed by the divided expanding piece 27, the expanding piece 27 is expanded as shown in FIGS. 7 (A) to (B). Moves in the radial outward direction R, and the tip diameter-expanded pipe portion 5 is formed (worked).

In order to form the tapered stepped 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.
After that, the mold 26 is divided in the expanding direction, and the processed pipe P ₀ is pulled out to produce a connected pipe P with a tip expanding pipe portion 5 as shown in FIGS. To be done.
From a long time ago, the manual working tool for expanding the diameter shown in FIG. 7 has been widely known. The reason is that the brazing pipe connection 63 as shown in FIG. 8 has been used for a long time as a refrigerant pipe or a household hot water (water) pipe. That is, because of the brazing pipe connection 63 that has been used for a long time, it was necessary to previously process the one end pipe diameter expansion pipe portion 5 shown in FIGS. 1 to 6 on one pipe 61. (Note that the other pipe 62 is directly inserted into the expanded pipe portion 5 without being processed, and the mutual fitting surface portion X ₅ is brazed.)
As described above, the present inventor has focused on the diameter-expanding work tool that has been widely used for pipe connection work by brazing, and the tip diameter-expanding pipe portion that can be easily machined by the work. By combining the unique shape and structure as shown, you can work safely without using heat such as brazing, and moreover, compared to the conventional example shown in FIG. A pipe joint structure that is excellent in workability for connecting pipes is proposed here.

As described in detail above, the present invention includes a flare joint body 20 having a male screw portion 20A and a tapered tip diameter reducing portion 20B, and a cap nut 15 having a female screw portion 15A screwed to the male screw portion 20A. In the connected pipe P, the tip diameter expanding tube portion 5 is formed from the tip end surface 3 to a predetermined axial center dimension L ₅ , and the tip diameter expanding tube portion 5 and the basic diameter tube portion 6 are provided. A tapered stepped portion 10 is formed at the boundary of the connecting tubular portion 31 inserted into the tip diameter-expanding pipe portion 5 of the pipe P and a sloped surface 32 that abuts the tip diameter-reducing taper portion 20B. A closed circular ring 25, which is provided with the in-core 30 and has the cap nut 15 screwed into the flare joint body 20 and is externally fitted to the tip diameter-expanded pipe portion 5 via the tapered stepped portion 10 of the pipe P. Is provided inside the cap nut 15, and a tip of the pipe P is applied by a radially diametrically urging force of the ring 25. The expanded tube portion 5 and the connecting tubular portion 31 of the in-core 30 are kept in a sealed state, and the axial force generated by screwing the cap nut 15 onto the flare joint body 20 is passed through the ring 25. Since it is transmitted to the in-core 30 so as to maintain the pressure-contact sealed state between the tapered tip end tapered portion 20B of the flare joint body 20 and the sloped surface 32 of the in-core 30, there is no concern about the durability of the sealing material against the refrigerant. Instead, it exhibits excellent sealing performance over a long period of time. Further, the problem of quality variation due to flaring at the work site is solved, parts having extremely super-precision claws 80 (see FIG. 9 and FIG. 10) can be omitted, and strong pull-out resistance is exhibited. The refrigerant pipe has a very large temperature difference of −50 ° C. to + 130 ° C., and it is possible to stably maintain a high sealing property for a long period of time under a severe working environment in which high pressure acts. became.

  Further, since a plurality of small triangular protrusions 36 each having a triangular shape or a Mt. Fuji cross section are formed on the outer peripheral surface of the connecting cylinder portion 31 of the in-core 30, the inside diameter expansion pipe portion 5 of the metal pipe P is expanded. It is possible to surely penetrate deep enough into the peripheral surface, exhibit a large pull-out resistance and a high sealing performance against the refrigerant.

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

When the wall thickness of the closed annular ring 25 is T ₂₅ and the wall thickness of the pipe P is T _p , 1.0 · T _p ≦ T ₂₅ ≦ 2.5 · T _p holds. Since the dimensions are set as described above, a strong elastic contraction / diameter urging force of the metal ring 25 is generated in the radial inward direction, and the metal pipe P is sufficiently strong with respect to the connecting tubular portion 31 of the in-core 30. It can be pressure-bonded, and exhibits stable and high sealing performance against refrigerant even with large temperature fluctuation from low temperature to high temperature, and has excellent durability.

3 Tip surface 5 Tip diameter expansion tube section 6 Basic diameter tube section
10 Tapered step
15 cap nut
15A female thread
20 Flare fitting body
20A male thread
20B Tip reduction taper
25 closed circular ring
30 incore
31 Connection tube
32 slope
36 Independent small protrusion P Pipe L ₅ Specified axial center dimension T ₂₅ Ring wall thickness T _p Pipe wall thickness

Claims (4)

A flare joint body (20) having a male screw portion (20A) and a tapered tip diameter reducing portion (20B), and a cap nut (15) having a female screw portion (15A) screwed to the male screw portion (20A). And
The connected pipe (P) is formed with a tip expanding tube portion (5) extending from the tip surface (3) to a predetermined axial center dimension (L ₅ ) and at the same time as the tip expanding tube portion (5). A tapered stepped portion (10) is formed at the boundary with the basic diameter pipe portion (6),
An in-core (30) having a connecting tube portion (31) inserted into the tip diameter-expanding pipe portion (5) of the pipe (P) and a sloped surface (32) contacting the tip diameter-reducing taper portion (20B). Equipped with
When the cap nut (15) is screwed into the flare joint body (20), the cap nut (15) is passed through the tapered stepped portion (10) of the pipe (P) and externally fitted to the tip diameter expanding pipe portion (5). Provide an annular ring (25) inside the cap nut (15),
By the radial inwardly reducing urging force of the ring (25), the sealed state between the tip expanding pipe portion (5) of the pipe (P) and the connecting tubular portion (31) of the incore (30) is maintained. Keep
Furthermore, the force in the axial direction caused by screwing the cap nut (15) onto the flare joint body (20) is transmitted to the incore (30) via the ring (25), and the flare joint body (20). ) The refrigerant pipe joint structure, characterized in that the tip diameter-reducing taper portion (20B) and the inclined surface (32) of the in-core (30) are kept in pressure-contact sealed state.   The refrigerant pipe joint structure according to claim 1, wherein a plurality of independent small protrusions (36) each having a triangular shape or a Mt. Fuji cross section are formed on the outer peripheral surface of the connection tubular portion (31) of the incore (30).   3. 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. When the wall thickness of the closed annular ring (25) is set to (T ₂₅ ), and the wall thickness of the pipe (P) is set to (T _p ), the dimensions are set so that the formula 1 is satisfied. Item 1. 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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