JP7833730B2 - Pipe fittings - Google Patents

Description

This invention relates to pipe fittings.

The pipe joint structure shown in Figures 6 to 8 was previously proposed by one of the inventors and is patented (see Patent Document 1).
In particular, for use in refrigerant piping, it offers excellent ease of connection and reliably prevents external leakage of refrigerant gas, making it highly regarded and widely used in the industry.

Patent No. 5736499

However, the inventors noticed that the conventional pipe fittings shown in Figures 6 to 8 have the following problems: (i)(ii) (iii)(iv).
In other words,
Problem (i): An internal tube portion 54 was deemed necessary to support the inner circumferential surface 51 of the tip of the pipe P. This required machining a concave circumferential groove 55 with an extremely small radial dimension R ₅₅ and a large depth L _55. As a result, it was difficult to reduce manufacturing costs and labor.
Problem (ii): When the two outer grooves 59A and 59B are narrowed, groove 59A shrinks in diameter, but groove 59B also has to narrow in the thrust direction by the distance it closes, which is a factor that increases the construction torque.
Problem (iii): The number of rotations required for tightening was high, and it was sometimes difficult for the worker to know how many rotations had been performed. Therefore, a torque wrench was necessary to confirm the completion of the work by torque management.
Problem (iv): Since the internal block body 60 has two identical outer grooves 59A and 59B, as shown in Figures 6 and 7, when the two grooves 59A and 59B are simultaneously closed and the bottom wall portion (thin-walled portion) 63 bites into the pipe P, the outer groove 59A on the tip side moves a long distance Z. That is, if the width dimension of each groove 59A and 59B is W, then it moves axially by Z = 1.5·W. Consequently, the thin-walled portion 63 of the outer groove 59A on the tip side may be damaged, or scratches over a long distance (Z = 1.5·W) may occur on the outer surface of the pipe P.

Therefore, the present invention aims to solve the problems (i), (ii), (iii), and (iv) described above and provide a pipe fitting that is easy to manufacture and reduces manufacturing man-hours and production costs.

The present invention comprises a joint body with a male thread, a cap nut screwed onto the male thread of the joint body, and a sleeve housed in the internal storage space of the cap nut; the sleeve has only one home plate-shaped groove on its outer circumferential surface near its tip; furthermore, the sleeve has only one rectangular seal groove on its inner circumferential surface at a position axially inward from the home plate-shaped groove, with an elastic seal material housed within the seal groove; if the thickness dimension from the inner tip of the home plate-shaped groove to the inner circumferential surface of the sleeve is defined as _T1 , and the thickness dimension from the bottom of the seal groove to the outer circumferential surface of the sleeve is defined as _T2 ≥ 1.5・T1, then _T2 is set to ≥ 1.5・_T1 .

Furthermore, regarding the radial depth dimension of the rectangular seal groove described above, the depth dimension at the tip side was set to be smaller than the depth dimension at the base side.
Furthermore, on the inner circumferential surface of the sleeve, a recess was formed extending from the vicinity of the axial position of the deepest tip of the home plate-shaped groove to an axially inward position.
Furthermore, the innermost tip of the home plate-shaped groove is formed in a rounded shape.
Furthermore, the internal insert portion, which is fitted into the inner circumferential surface of the tip of the inserted pipe, has been omitted.
Furthermore, the groove width dimension of the home plate-shaped groove was set to be equal to the screw pitch of the threaded portion of the cap nut and fitting body.

Furthermore, by manually tightening the cap nut by the worker, a pre-assembled state is achieved where there is no axial gap between the fitting body, cap nut, and sleeve. Then, by using a tool to rotate the cap nut approximately one full turn, the pipe fitting connection can be completed.

According to the present invention, since only a single home plate-shaped groove needs to be compressed, the number of rotations required for the cap nut is reduced, making the connection work quick and easy. Furthermore, the seal groove hardly deforms under compression, and the pipe-biting portion on the inner circumference of the sleeve corresponding to the deepest tip of the home plate-shaped groove bites into the pipe radially with almost no axial movement relative to the outer surface of the pipe. Therefore, the outer surface of the pipe is not roughened, and the function of preventing external fluid leakage is fully demonstrated.
Furthermore, since the pipe-biting portion on the inner circumference of the sleeve corresponding to the deepest tip of the home plate-shaped groove hardly moves in the axial direction, the installation torque required to rotate the cap nut can be significantly reduced. This torque reduction allows for easy installation even when increasing the groove bottom thickness at the deepest tip of the groove or widening the groove to increase the degree of constriction. It also reduces the risk of cutting the groove bottom.

This cross-sectional view shows one embodiment of the present invention, with the upper half showing the intermediate connection state with the sleeve uncompressed and the lower half showing the completed connection state with the sleeve compressed. This is an enlarged cross-sectional view of the main part for explaining its function. This is an enlarged cross-sectional view of the main part illustrating the dimensional relationships. This is an enlarged cross-sectional view of the main part for explaining its function. This is an enlarged cross-sectional view of a key part showing a modified example. This is a cross-sectional view showing a conventional example with the cap nut not tightened. This is a cross-sectional view showing a conventional example with the cap nut tightened to completion. This is an enlarged cross-sectional view of a conventional example.

The present invention will be described in detail below based on the illustrated embodiments.
Figure 1 shows one embodiment of the present invention, where the upper half of the portion above the axial line (center line) _L0 shows the uncompressed sleeve state, and the lower half of the portion below the axial line _L0 shows the compressed sleeve state, indicating that the connection is complete.
Furthermore, Figures 2 and 3 are enlarged views of the main parts of the upper half of Figure 1.

In Figures 1 to 3, the pipe fitting according to the present invention comprises a fitting body 1 with a male thread 2 and a cap nut 3, and a metal compression-deformable sleeve 7 is housed in the internal storage space 10 of the cap nut 3. The cap nut 3 is screwed onto the male thread 2 of the fitting body 1.
The sleeve 7 described above has only one home plate-shaped groove 9 on its outer surface 5 near the tip. In other words, while the conventional examples in Figures 6 to 8 had two grooves 59A and 59B, this has been halved.

Furthermore, the sleeve 7 has a single rectangular seal groove 12 on its inner circumferential surface 7A at a position axially inward from the groove 9. An elastic seal material 13, such as an O-ring, is housed within this seal groove 12.
Furthermore, regarding the radial depth dimension H of the rectangular cross-section seal groove 12, as shown in Figure 3, it is desirable to set the tip-side depth dimension _H2 to be smaller than the base-side depth dimension _H1 .

Incidentally, as shown in Figure 1, and as is clear when compared with conventional examples (Figures 6, 7, and 8), the internal cylinder portion 54 that is inserted into the inner circumferential surface of the tip of the pipe P has been completely omitted.

Furthermore, in the present invention, the cross-sectional shape of the home plate-shaped groove 9 may be a square shape with a sharp tip at the back, as shown in the conventional Figures 6 and 8. However, it is desirable to make the tip 9A at the back a predetermined rounded shape, as shown in Figures 2, 3, and 4(A). Moreover, if the thickness dimension from the tip 9A at the back of the home plate-shaped groove 9 to the inner circumferential surface 7A of the sleeve is set to _T1 , and the thickness dimension from the bottom 12B of the rectangular cross-section seal groove 12 to the outer circumferential surface 7C of the sleeve is set to _T2 ,
T ₂ ≧ 1.5・T ₁ ...Number 1
Set _T1 and _T2 so that the following condition is met.

When _T2 < 1.5 and _T1 , the following problems occur, which is undesirable.
In other words, when the cap nut 3 is tightened (while rotating), the groove bottom wall portion 12E is prone to bending deformation (due to its thinness), and the groove width dimension W ₁₂ decreases. Consequently, the amount of compression of the recessed groove 9 decreases (the amount of constriction on the pipe P decreases), resulting in a problem where the pipe slippage prevention performance deteriorates.
Furthermore, if the wall thickness dimension _T2 changes (differs) depending on the axial position, as in the specific example shown in Figure 3, the wall thickness dimension measured at the thinnest point (minimum wall thickness dimension) shall be referred to as the wall thickness dimension _T2 .

Next, the plastic deformation of the groove 9 will be explained in Figures 4 and 1.
Starting from the uncompressed state shown in Figure 4(A), when the sleeve 7 receives an axial compressive force F due to the screwing of the cap nut 3 (see Figure 2), as shown in Figures 4(B) and 4(C), the thin-walled portion (bottom wall portion) 16 on the groove bottom side immediately undergoes uniform plastic deformation in the radial inward direction over the entire 360° circumference. While plastically deforming into a shape close to a triangle, it bites into the outer surface of the pipe P, forming a closed circular annular biting portion 18 that is close to a triangle (see the lower half of Figure 1).

Figure 4 illustrates the case where the compressive force F acts in a direction parallel to the axis line _L0 of the pipe P (in Figure 1). However, it is also preferable to apply the force in a direction toward the innermost tip 9A (thin-walled portion 16) of the groove 9, as shown in Figure 2 or Figure 5 (described later).
In other words, the groove 9 itself deforms in a direction that narrows with almost no resistance to the force F, but it is the thin-walled portion 16 that resists the force F.
Then, as shown in Figures 1, 2, 3, or 5, the tip surface 7T of the sleeve 7 is made into a sloped surface at a predetermined angle θ such that the force F is directed in the direction described above. That is, the force F is applied in a direction that intersects the axis (center line) at a predetermined angle θ.

As explained in Figures 4 and 1 (lower half), when a force F is applied, the groove 9 deforms in a closing direction, forming a triangular, mountain-shaped closed circular annular recess 18, and an anti-pulling force acts to prevent the pipe P from being pulled out.
However, in order to adapt to usage conditions in which an even greater tensile force is applied to the pipe P, a recessed portion 19 is formed on the inner circumferential surface 7A of the sleeve 7, as shown in Figure 5.

Specifically, on the inner circumferential surface 7A of the sleeve 7, a recessed portion 19 is formed extending from the vicinity 22 of the axial position of the innermost tip 9A of the home plate-shaped groove 9 to a position axially inward Y.
Moreover, a sharp edge 20 is formed in this recessed portion 19 near the front and rear inner tip 9A 22.

The edge 20 formed at one open end of the recessed portion 19 will, when the groove 9 is closed, have a sharp edge 20Y protruding from a part of the mountain-shaped recessed portion 18 shown in Figure 4(C) (even if the shape changes slightly).
In other words, in the state where the pipe connection is completed as shown in the lower half of Figure 1, it exhibits strong pull-out resistance against pipe P (the sharp edge 20Y is omitted from the illustration in Figure 1).
As shown in Figures 4(A) and 5, the innermost tip 9A of the home plate-shaped groove 9 is formed in a rounded shape.

Next, as shown in the upper half of Figure 1 (above the axis line L ₀ ), it is desirable to set the groove width dimension W ₉ of the home plate-shaped groove 9 to be equal to the screw pitch P ₃ of the screw-fitting portion of the cap nut 3 and the joint body 1.
By setting _W9 = _P3 in this way, the following operations can be achieved.
In other words, by manually tightening the cap nut 3 by the worker, a pre-assembled state is created in which there is no axial gap between the joint body 1, the cap nut 3, and the sleeve 7. Then, by using a work tool to rotate the cap nut 3 approximately one full turn, the pipe joint connection can be completed.

To further explain, the upper half of Figure 1 shows a pre-assembled state where the worker has hand-tightened the joint body 1, the cap nut 3, and the sleeve 7, eliminating any axial gaps (lightly tightened). Then, by using a wrench or other tool to rotate the cap nut 3 approximately one full turn, the cap nut 3 advances axially by the screw pitch P _3. The groove width dimension W ₉ of the recessed groove 9, which is equal to this screw pitch P ₃ , becomes zero, resulting in the completed pipe joint connection state shown in the lower half of Figure 1. Thus, since it only requires one full rotation with a wrench or other tool, the installation procedure can be changed from torque control to rotation speed control.
In other words, the connection work can be completed easily and reliably without requiring skilled workers, and even though the internal condition of the pipe fitting is completely invisible from the outside.

As described in detail above, the present invention comprises a joint body 1 with a male thread 2, a cap nut 3 screwed onto the male thread 2 of the joint body 1, and a sleeve 7 housed in the internal storage space 10 of the cap nut 3; the sleeve 7 has only one home plate-shaped groove 9 on its outer peripheral surface 5 near its tip; furthermore, the sleeve 7 has only one rectangular seal groove 12 on its inner peripheral surface 7A at a position axially inward from the home plate-shaped groove 9, and an elastic seal material 13 is housed in the seal groove 12; if the thickness dimension from the inner tip 9A of the home plate-shaped groove 9 to the inner peripheral surface 7A of the sleeve is _T1 , and the thickness dimension from the bottom 12B of the seal groove 12 to the outer peripheral surface 7C of the sleeve is _T2 , then _T2 ≥ 1.5・T As configured as in ₍₁₎ , a large compressive force F acts on the sleeve 7 as the cap nut 3 is screwed in, and even if the home plate-shaped groove 9 undergoes plastic deformation as shown in Figure 4 (A) → (B) → (C), the (thick) bottom wall portion 12E of the seal groove 12 does not undergo plastic deformation. Therefore, the groove width dimension W ₁₂ of the rectangular seal groove 12 hardly decreases.

In the conventional examples shown in Figures 6, 7, and 8, as explained in detail as problem (ii) above, the bottom wall portion (thin-walled portion) 63 of the outer peripheral groove 59A on the tip side may develop scratches over a long distance (Z = 1.5·W), which may cause the sealed fluid to leak to the outside. Furthermore, there was a risk that the thin-walled portion 63 of the outer peripheral groove 59A on the tip side may be damaged, resulting in a large external leak.
In this invention, the aforementioned problem (ii) is successfully solved by the seal groove 12, which does not undergo plastic deformation.
Specifically, the innermost tip 9A of the (single) groove 9 shown in Figure 3 only needs to move axially by about half the groove width W ₉ of the groove 9—that is, 0.5・W _9. Therefore, the thin-walled portion 16 can securely bite into the pipe P with almost no axial movement, preventing external leakage of the fluid.
Thus, by reducing the number of conventional outer grooves 59A and 59B shown in Figure 6 to half, and using only one groove 9, external fluid leakage can be reduced (compared to the conventional design).

Furthermore, regarding the radial depth dimension H of the rectangular cross-section seal groove 12, by setting the tip-side depth dimension _H2 to be smaller than the base-side depth dimension _H1 , the following effects are achieved. In other words, when a large compressive force F is applied to the tip surface 7T of the compression-deformed sleeve 7, it has been found that the seal groove 12 undergoes elastic deformation such that the tip side 32 moves radially outward and the base side 31 moves radially inward.
Therefore, by setting the cross-sectional shape such that _H1 > _H2 when no external force is acting on the compression deformation sleeve 7, it becomes possible to approach a normal rectangle where _H1 = _H2 when a compressive force F is applied. In other words, the sealing material 13 can reliably perform its sealing performance within the normal rectangular sealing groove 12.

Furthermore, on the inner circumferential surface 7A of the sleeve 7, a recessed portion 19 is formed extending from the vicinity of the axial position of the innermost tip 9A of the home plate-shaped groove 9 to an axially inward position. Therefore, an edge 20Y, as shown by the dashed line in Figure 4(C), is formed on the base-side slope of the triangular, mountain-shaped recessed portion 18 when the groove 9 is closed. That is, the edge 20Y increases the force preventing the pipe P from being pulled out. Note that the recessed portion 19 shown in Figure 5 deforms as shown by the dashed line 19Y in Figure 4(C).

Furthermore, since the innermost tip 9A of the home plate-shaped groove 9 is formed in a rounded shape, the wall thickness dimension _T1 (see Figure 2) can be set to be sufficiently large, and as shown in Figures 4(A), (B), and (C), it smoothly forms a large bulge and bites deeply into the outer surface of the pipe.

Furthermore, since the internal insertion cylinder portion, which is fitted into the inner circumferential surface of the tip of the inserted pipe P, is omitted, the troublesome machining of the concave circumferential groove 55 shown in Figure 8 can be eliminated. This reduces manufacturing time (labor).

Furthermore, by setting the groove width dimension W ₉ of the home plate-shaped groove 9 to be equal to the screw pitch P ₃ of the threaded portion of the cap nut 3 and the fitting body 1, it is possible to complete the pipe fitting connection by first rotating the cap nut 3 by hand tightening it, thereby eliminating the axial gap between the fitting body 1, the cap nut 3, and the sleeve 7 in a pre-assembled state, and then using a work tool to rotate the cap nut 3 approximately one full turn. To further explain, the upper half of Figure 1 shows the pre-assembled state in which the fitting body 1, the cap nut 3, and the sleeve 7 have been lightly tightened by hand, eliminating the axial gap between them. Subsequently, by using a work tool such as a wrench and applying a large torque to rotate the cap nut 3 approximately one full turn, the cap nut 3 advances axially by the screw pitch P _3. The groove width dimension W ₉ of the groove 9, which is equal to this screw pitch P ₃ , becomes zero, resulting in the completed pipe fitting connection state shown in the lower half of Figure 1. In other words, the connection work can be completed easily and reliably without requiring skilled workers, and even though the internal condition of the pipe fitting is completely invisible from the outside.

In this way, by rotating the cap nut 3 by hand tightening, the axial gap between the fitting body 1, the cap nut 3, and the sleeve 7 is eliminated, creating a pre-assembled state. Then, by using a tool to rotate the cap nut 3 approximately one full turn, the pipe fitting connection can be completed. This prevents problems such as insufficient connection or, conversely, excessive tightening force that damages the components.

1. Joint body 2. Male thread 3. Cap nut 5. Outer surface near tip 7. Sleeve 7A. Inner surface 7C. The same surface 9. Groove 9A. Inner tip
10 Internal storage space
12 seal grooves
12B Groove bottom
13. Sealant
19 Recessed section H Depth dimension _H1 Base end depth dimension _H2 Tip end depth dimension P Pipe _P3 Screw pitch _T1 Wall thickness dimension _T2 Wall thickness dimension _W9 Groove width dimension

Claims (6)

The fitting comprises a fitting body (1) with a male thread (2), a cap nut (3) that is screwed onto the male thread (2) of the fitting body (1), and a metal, compressible sleeve (7) that is housed in the internal storage space (10) of the cap nut (3).
The above sleeve (7) has only one home plate-shaped groove (9) on its outer surface (5) near the tip,
Furthermore, the sleeve (7) has a single rectangular seal groove (12) on its inner circumferential surface (7A) at a position axially inward from the home plate-shaped recess (9), and an elastic seal material (13) is housed within the seal groove (12).
Even if the cross-section of the home plate-shaped groove (9) undergoes plastic deformation due to the screwing of the cap nut (3), plastic deformation of the groove bottom wall portion (12E) from the groove bottom portion (12B) of the seal groove (12) to the outer circumferential surface (7C) of the sleeve is suppressed. In this way, the thickness dimension from the inner tip (9A) of the home plate-shaped groove (9) to the inner circumferential surface (7A) of the sleeve is set to ( _T1 ), and the thickness dimension from the groove bottom portion (12B) of the seal groove (12) to the outer circumferential surface (7C) of the sleeve is set to ( _T2 ), such that _T2 ≥ 1.5・_T1 .
A pipe fitting characterized by the omission of an internal insertion tube portion that is inserted into the inner circumferential surface of the tip of the pipe (P) to be inserted . The pipe fitting according to claim 1, wherein, with respect to the radial depth dimension (H) of the rectangular cross-section seal groove (12) described above, the tip-side depth dimension ( _H2 ) is set to be smaller than the base-side depth dimension ( _H1 ). The pipe fitting according to claim 1, wherein a recessed portion (19) is formed on the inner circumferential surface (7A) of the sleeve (7) extending from the vicinity of the axial position of the innermost tip (9A) of the home plate-shaped groove (9) to an axially inward position. The pipe fitting according to claim 1, wherein the innermost tip (9A) of the home plate-shaped groove (9) is formed in a rounded shape. The pipe fitting according to claim 1, wherein the groove width dimension (W ₉ ) of the home plate-shaped groove (9) is set to be equal to the screw pitch (P ₃ ) of the screw-fitting portion of the cap nut (3) and fitting body (1). The operator rotates the cap nut (3) by hand tightening it to create a pre-assembled state where there is no axial gap between the joint body (1), the cap nut (3), and the sleeve (7),
The pipe fitting according to claim 5 , wherein the pipe fitting connection can be completed by rotating the cap nut (3) by approximately one turn using a work tool.