Pipe joint

Abstract

To provide a pipe joint that is compact, can exert strong pipe withdrawal resistance, and is readily manufactured.SOLUTION: A pipe joint includes: a joint body 1 with a male screw 2; a box nut 3 screwed to the male screw 2 of the joint body 1; and a sleeve 7 stored in an internal storage space 10 of the box nut 3. The sleeve 7 has a single line of home base-shape recessed groove 9 and a single piece of a rectangular seal groove 12 with a seal material 13.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pipe joint. [Background technology]

[0002] The pipe joint having the structure shown in Figs. 6 to 8 was previously proposed by (one of) the present inventors and has been patented (see Patent Document 1). In particular, when used for refrigerant piping, the pipe connection is easy and the leakage of refrigerant gas to the outside can be reliably prevented, and therefore the device has been well received and is widely used in the industry. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5736499 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the present inventors have noticed that the conventional pipe joints shown in Figs. 6 to 8 have the following problems (i), (ii), (iii) and (iv). That is, Problem (i): It is considered necessary to have an inner cylindrical portion 54 for supporting the inner peripheral surface 51 of the tip of the pipe P, and the radial dimension R 55 is extremely small and the depth dimension L 55 Therefore, it was difficult to reduce the manufacturing cost and the number of manufacturing steps (efforts). Problem (ii): When the two outer peripheral grooves 59A, 59B are narrowed, the diameter of groove 59A is reduced, but the pipe must also be narrowed in the thrust direction by the distance that groove 59B closes, which results in high installation torque. Problem (iii): The number of turns required for tightening was so high that the worker sometimes lost track of how many turns it had been made. To check whether the work was complete, a torque wrench was needed to manage the torque. Problem (iv): The built-in block body 60 had two identically shaped outer peripheral grooves 59A, 59B, so as shown in Figures 6 to 7, when the two grooves 59A, 59B are closed at the same time and the bottom wall portion (thin portion) 63 is bitten into the pipe P, the outer peripheral groove 59A on the tip side moves a long distance Z. In other words, if the groove width dimension of each of the grooves 59A, 59B is W, it moves in the axial direction by Z = 1.5 · W. Therefore, the thin portion 63 of the outer peripheral groove 59A on the tip side may be damaged, or scratches over a long distance (Z = 1.5 · W) may occur on the outer peripheral surface of the pipe P.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to solve the above problems (i), (ii), (iii) and (iv) and to provide a pipe joint which is easy to manufacture and can reduce the number of manufacturing steps and manufacturing costs. [Means for solving the problem]

[0006] The present invention comprises a fitting body with a male thread, a cap nut screwed onto the male thread of the fitting body, and a sleeve stored in the internal storage space of the cap nut; the sleeve has only a single groove with a home plate shaped cross section on its outer peripheral surface near its tip; the sleeve further has only a single seal groove with a rectangular cross section on its inner peripheral surface axially inward from the home plate shaped groove, and an elastic seal material is disposed within the seal groove; where T1 is the thickness dimension from the inner tip of the home plate shaped groove to the inner peripheral surface of the sleeve, and T2 is the thickness dimension from the bottom of the seal groove to the outer peripheral surface of the sleeve, T2 is set such that T2≧1.5·T1.

[0007] Furthermore, with regard to the radial depth of the above-mentioned seal groove having a rectangular cross section, the depth at the tip end side is set smaller than the depth at the base end side. Further, a recess is formed on the inner peripheral surface of the sleeve, extending from near the axial position of the innermost tip of the home plate-shaped groove to an axially inward position. The innermost tip of the home plate-shaped groove is formed in a rounded shape. Furthermore, the inserting tube portion that is inserted into the inner peripheral surface of the tip of the pipe to be inserted is omitted. In addition, the groove width dimension of the home plate-shaped groove is set to be equal to the thread pitch of the screw-fitting portion of the cap nut / joint body.

[0008] In addition, the cap nut can be rotated by hand tightening by an operator to create a preliminary assembly state in which there is no gap in the axial direction between the joint body, the cap nut, and the sleeve; and then the cap nut can be rotated approximately one turn using a work tool to complete the connection of the pipe joint. Effect of the Invention

[0009] According to the present invention, since only a single cross-sectional home plate-shaped groove needs to be compressed, the number of rotations of the cap nut is reduced, making the connection work quicker and easier. Also, the seal groove hardly deforms when compressed, and the pipe-biting part on the inner circumference of the sleeve corresponding to the innermost tip of the home plate-shaped groove bites into the radial direction with almost no axial movement relative to the outer circumference of the pipe, so the outer circumference of the pipe is not roughened and the function of preventing external leakage of fluid is fully demonstrated. Furthermore, the part of the sleeve's inner circumference where the pipe bites into, which corresponds to the deepest tip of the home plate-shaped groove, hardly moves in the axial direction, so the torque required to rotate the cap nut can be significantly reduced. This torque reduction makes it easy to install the nut even if the groove bottom thickness at the deepest tip of the groove is increased (thickened) and the groove width is widened to increase the amount of squeezing. The risk of the groove bottom being cut off can also be reduced. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing one embodiment of the present invention, in which the upper half shows a state during connection with the sleeve uncompressed, and the lower half shows a state after connection is completed with the sleeve compressed. [Diagram 2] FIG. 4 is an enlarged cross-sectional view of a main part for explaining the operation. [Diagram 3] FIG. 4 is an enlarged cross-sectional view of a main portion illustrating dimensional relationships. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a main part for explaining the operation. [Diagram 5] FIG. 11 is an enlarged cross-sectional view of a main part showing a modified example. [Figure 6] FIG. 13 is a cross-sectional view showing a conventional example in an untightened state of the cap nut. [Figure 7] FIG. 13 is a cross-sectional view showing a conventional example in a state where the cap nut has been tightened. [Figure 8] FIG. 11 is an enlarged cross-sectional view of a conventional example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below based on the illustrated embodiments. FIG. 1 shows one embodiment of the present invention, in which the upper half of the region above the axial line (center line) L0 shows the sleeve in an uncompressed state, and the lower half of the region below the axial line L0 shows the sleeve in a compressed state after connection is completed. 2 and 3 are enlarged views of the main part of the upper half of FIG.

[0012] 1 to 3, the pipe joint according to the present invention comprises a joint body 1 with a male thread 2, and a cap nut 3, and a metallic compression deformation sleeve 7 is stored in an internal storage space 10 of the cap nut 3. The cap nut 3 is screwed onto the male thread 2 of the joint body 1. The sleeve 7 has only one groove 9 having a home plate-shaped cross section on the outer circumferential surface 5 near the tip. In other words, the two grooves 59A, 59B in the conventional example of Figs. 6 to 8 are halved.

[0013] Furthermore, the sleeve 7 has a single seal groove 12 having a rectangular cross section on the inner circumferential surface 7A at a position axially inward from the recessed groove 9. An elastic seal material 13 such as an O-ring is fitted in the seal groove 12. Regarding the radial depth dimension H of the rectangular cross-section seal groove 12, it is preferable to set the tip end depth dimension H2 smaller than the base end depth dimension H1, as shown in FIG.

[0014] Incidentally, as shown in FIG. 1, and as is clear when compared with the conventional example (FIGS. 6, 7, and 8), the inner cylindrical portion 54 that is inserted into the inner peripheral surface of the tip of the pipe P is completely omitted.

[0015] In the present invention, the cross-sectional shape of the home-plate-shaped groove 9 may be a sharp rectangular shape at the innermost tip as shown in the conventional figures 6 and 8. However, it is preferable that the innermost tip 9A has a predetermined radius as shown in figures 2, 3 and 4(A). Furthermore, if the thickness dimension from the innermost 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 groove bottom 12B of the seal groove 12 having a rectangular cross section to the outer peripheral surface 7C of the sleeve is T2, then T2 ≧ 1.5 T1 number 1 Set T1 and T2 so that the following holds:

[0016] If T2 < 1.5 T1, the following problems will occur, which is undesirable: That is, when the cap nut 3 is tightened (while rotating), the groove bottom wall portion 12E is easily curved and deformed (due to its thin wall), and the groove width dimension W 12 Accordingly, the amount of compression of the recessed groove 9 decreases (the amount of squeezing of the pipe P decreases), causing a problem of a decrease in the pipe removal prevention performance. In addition, when the thickness dimension T2 varies (differs) depending on the axial position, as in the specific example shown in Figure 3, the thickness dimension measured at the thinnest point (minimum thickness dimension) will be referred to as the thickness dimension T2.

[0017] Next, the plastic deformation of the groove 9 will be described with reference to FIG. 4 and FIG. When the sleeve 7 receives an axial compressive force F as the cap nut 3 is screwed in (see FIG. 2) from the uncompressed state shown in FIG. 4(A), the thin-walled portion (bottom wall portion) 16 at the bottom of the groove immediately undergoes plastic deformation in the radially inward direction evenly over the entire circumference of 360°, as shown in FIG. 4(B) and (C). As it plastically deforms into a mountain shape close to a triangle, it bites into the outer circumferential surface of the pipe P, forming a closed annular bite portion 18 with a mountain shape close to a triangle (see the lower half of FIG. 1).

[0018] 4 illustrates a case where the compressive force F acts in a direction parallel to the axial line L0 of the pipe P (in FIG. 1). However, it is also preferable to apply the compressive force F in a direction toward the innermost tip 9A (thin wall portion 16) of the groove 9, as shown in FIG. 2 or FIG. 5 (described later). That is, the recessed groove 9 itself deforms in the direction of narrowing with almost no resistance to the force F, but it is the thin-walled portion 16 that resists the force F. 1, 2, 3, or 5, the tip end surface 7T of the sleeve 7 is made to have an inclined surface at a predetermined angle θ so that the force F is directed in the above-mentioned direction. That is, the force F is applied in a direction intersecting the axial line (center line) at the predetermined angle θ.

[0019] As explained in Figure 4 and Figure 1 (lower half), when force F is applied, the groove 9 deforms in the closing direction, forming a closed annular biting portion 18 having a mountain shape close to a triangle, and a pull-out prevention force acts to prevent the pipe P from being pulled out. However, in order to accommodate usage conditions in which a larger pulling force acts on the pipe P, a recess 19 is formed on the inner circumferential surface 7A of the sleeve 7 as shown in FIG.

[0020] Specifically, the inner peripheral surface 7A of the sleeve 7 has a recess 19 formed from a position 22 in the vicinity of the axial position of the innermost tip 9A of the home plate-shaped groove 9 to a position Y inward in the axial direction. Moreover, in this recess 19, sharp edges 20 are formed on the side of the vicinity 22 of the front / rear innermost tip 9A.

[0021] The edge 20 formed at one open end of the recess 19 has a sharp edge 20Y protruding from part of the mountain-shaped biting portion 18 shown in Figure 4(C) when the groove 9 is in a closed state (even if the shape changes slightly). That is, in the state where the pipe connection is completed as shown in the lower half of FIG. 1, a strong pull-out resistance force is exerted on the pipe P (the sharp edge 20Y is omitted in FIG. 1). As shown in Figs. 4(A) and 5, the innermost tip 9A of the home-plate-shaped groove 9 is formed in a rounded shape.

[0022] Next, as shown in the upper half of Figure 1 (above the axis line L0), it is desirable to set the groove width dimension W9 of the home-base-shaped groove 9 equal to the thread pitch P3 of the screw-on portion of the cap nut 3 and the joint body 1. In this way, by setting W9=P3, the following work can be achieved: That is, the cap nut 3 is rotated by hand tightening by the operator to create a preliminary assembly state in which there is no gap in the axial direction between the joint body 1, the cap nut 3, and the sleeve 7, and then the cap nut 3 is rotated approximately one turn using a work tool to complete the pipe joint connection.

[0023] To explain further, the upper half of Fig. 1 shows a preliminary assembly state in which an operator has manually tightened the fitting body 1, the cap nut 3, and the sleeve 7, eliminating any gap in the axial direction between them (lightly tightened). If the cap nut 3 is then rotated approximately once using a work tool such as a wrench, the cap nut 3 will advance in the axial direction by the thread pitch P3. The groove width dimension W9 of the recessed groove 9, which is equal to this thread pitch P3, becomes zero, and the pipe fitting is in a connected state as shown in the lower half of Fig. 1. In this way, since it is sufficient to rotate it once using a work tool such as a wrench, the construction procedure can be changed from torque management to rotation speed management. In other words, the connecting work can be completed easily and reliably without requiring the skilled worker and even though the inside of the pipe joint cannot be seen at all from the outside.

[0024] As described above in detail, 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 stored in an internal storage space 10 of the cap nut 3; the sleeve 7 has only one home-base-shaped groove 9 on its outer peripheral surface 5 near its tip; the sleeve 7 further has only one rectangular seal groove 12 on its inner peripheral surface 7A at a position axially inward from the home-base-shaped groove 9, and an elastic seal material 13 is disposed within the seal groove 12; if the thickness dimension from the inner tip 9A of the home-base-shaped groove 9 to the sleeve inner peripheral surface 7A is T1 and the thickness dimension from the groove bottom 12B of the seal groove 12 to the sleeve outer peripheral surface 7C is T2, then T2≧ Since the groove width W of the rectangular seal groove 12 is set to 1.5·T1, even if a large compressive force F acts on the sleeve 7 as the cap nut 3 is screwed in and the home plate-shaped groove 9 is plastically deformed from (A) to (B) to (C) in FIG. 4, the (thicker) groove bottom wall 12E of the seal groove 12 does not plastically deform. 12 hardly decreases at all.

[0025] In the conventional example shown in Figures 6, 7 and 8, as described above in detail, the problem (ii) is that the bottom wall portion (thin portion) 63 of the outer peripheral groove 59A on the tip side generates scratches over a long distance (Z = 1.5 W), which may cause the sealed fluid to leak to the outside. Furthermore, the thin portion 63 of the outer peripheral groove 59A on the tip side may be damaged, which may cause a large amount of leakage to the outside. In the present invention, the above problem (ii) is successfully solved by the above seal groove 12 which is not plastically deformed. Specifically, the innermost tip 9A of the (single) groove 9 shown in Figure 3 only needs to move in the axial direction about half the groove width W9 of the groove 9, i.e., 0.5 W9. Therefore, the thin-walled portion 16 fits securely into the pipe P with almost no axial movement, preventing the fluid from leaking out. In this way, the number of the conventional two outer peripheral grooves 59A, 59B shown in FIG. 6 has been halved to provide a single groove 9, thereby making it possible to reduce external leakage of fluid (compared to the conventional case).

[0026] Furthermore, by setting the tip end depth dimension H2 smaller than the base end depth dimension H1 with respect to the radial depth dimension H of the above-mentioned rectangular cross-section seal groove 12, the following action and effect are achieved: That is, it has been found that when a large compressive force F is applied to the tip end surface 7T of the compressively deformable sleeve 7, elastic deformation occurs in the seal groove 12 such that the tip end side 32 moves radially outward and the base end side 31 moves radially inward. Therefore, by setting the cross-sectional shape such that H1>H2 when no external force is acting on the compressively deformable sleeve 7, it is possible to approximate a regular rectangle where H1=H2 when a compressive force F is acting on it. In other words, the seal material 13 can reliably exhibit sealing performance within the regular rectangular seal groove 12.

[0027] Furthermore, since the recess 19 is formed on the inner peripheral surface 7A of the sleeve 7 from near the axial position of the innermost tip 9A of the home plate-shaped recessed groove 9 to an axially inward position, an edge 20Y as shown by the imaginary line in Fig. 4(C) is formed on the base end side slope of the nearly triangular mountain-shaped biting portion 18 when the recessed groove 9 is in a closed state. That is, the edge 20Y increases the force preventing the pipe P from being pulled out. The recess 19 shown in Fig. 5 is deformed as shown by the two-dot chain line 19Y in Fig. 4(C).

[0028] Furthermore, since the inner tip 9A of the home-base-shaped groove 9 is formed in an arched shape, the wall thickness dimension T1 (see FIG. 2) can be set sufficiently large, so that the groove 9 penetrates deeply into the outer circumferential surface of the pipe while smoothly forming a large bulge, as shown in FIG. 4(A), (B) and (C).

[0029] In addition, since the insertion tube portion that is inserted into the inner peripheral surface of the tip of the inserted pipe P is omitted, the troublesome cutting process of the conventional concave circumferential groove 55 shown in Fig. 8 can be omitted. This reduces the number of manufacturing steps (effort).

[0030] In addition, by setting the groove width dimension W9 of the home base type groove 9 to be equal to the thread pitch P3 of the screwing portion of the cap nut 3 and the joint body 1, the cap nut 3 can be rotated by hand tightening by an operator to create a preliminary assembly state in which there is no gap in the axial direction between the joint body 1, the cap nut 3, and the sleeve 7, and then the cap nut 3 can be rotated approximately once using a tool to create a pipe joint connection completion state. To explain further, the upper half of FIG. 1 shows a preliminary assembly state in which there is no gap in the axial direction between the joint body 1, the cap nut 3, and the sleeve 7 (lightly tightened) by hand tightening by an operator. Then, by rotating the cap nut 3 approximately once with a large torque using a tool such as a wrench, the cap nut 3 advances in the axial direction by the thread pitch P3. The groove width dimension W9 of the groove 9, which is equal to the thread pitch P3, becomes zero, and the pipe joint connection completion state shown in the lower half of FIG. 1 is achieved. In other words, the connecting work can be completed easily and reliably without requiring the skilled worker and even though the inside of the pipe joint cannot be seen at all from the outside.

[0031] In this way, the cap nut 3 is rotated by hand tightening by the worker to create a preliminary assembly state in which there is no gap in the axial direction between the joint body 1, the cap nut 3, and the sleeve 7, and then the cap nut 3 is rotated approximately once using a power tool to complete the pipe joint connection.This makes it possible to prevent problems such as an insufficient connection due to tightening work using a power tool, or, conversely, the application of excessive tightening force that causes damage to components. [Explanation of symbols]

[0032] 1 Fitting body 2 Male thread 3 Cap nuts 5. Outer periphery near the tip 7 Sleeve 7A Inner surface 7C Peripheral surface 9 Groove 9A Inner tip 10. Interior storage space 12 Seal groove 12B Groove bottom 13 Sealing material 19 Depression H Depth dimension H1 Base end depth dimension H2 Tip side depth dimension P Pipe P3 thread pitch T1 wall thickness T2 wall thickness W9 groove width dimension

Claims

1. The joint body (1) has a male thread (2), a cap nut (3) that is screwed onto the male thread (2) of the joint body (1), and a sleeve (7) that is stored in an internal storage space (10) of the cap nut (3), The sleeve (7) has only one groove (9) having a home plate-shaped cross section on the outer peripheral surface (5) near the tip, Further, the sleeve (7) has only one seal groove (12) having a rectangular cross section on its inner circumferential surface (7A) at a position axially inward from the home plate-shaped recessed groove (9), and an elastic seal material (13) is fitted in the seal groove (12); The thickness dimension from the inner end (9A) of the home base-shaped groove (9) to the inner peripheral surface (7A) of the sleeve is (T 1 ), and the thickness dimension from the groove bottom (12B) of the seal groove (12) to the outer peripheral surface (7C) of the sleeve is (T 2 ), then T 2 ≧ 1.5・T 1 A pipe joint characterized in that the pipe joint is configured as follows.

2. Regarding the radial depth dimension (H) of the above-mentioned rectangular cross-sectional seal groove (12), the base end side depth dimension (H 1 ) than the tip side depth dimension (H 2 2. A pipe joint according to claim 1, wherein the distance between the inner and outer periphery of the pipe is set small.

3. 2. A pipe joint as claimed in claim 1, wherein a recess (19) is formed on the inner peripheral surface (7A) of said sleeve (7) from near the axial position of the innermost tip (9A) of said home plate-shaped groove (9) to an axially inward position.

4. 2. A pipe joint according to claim 1, wherein a tip end (9A) of the innermost portion of said home plate shaped groove (9) is formed in a rounded shape.

5. 2. A pipe joint as claimed in claim 1, wherein the inner cylindrical portion inserted into the inner peripheral surface of the tip of the pipe (P) is omitted.

6. The groove width dimension (W 9 ) is the thread pitch (P 3 2. A pipe joint according to claim 1, wherein said first and second contacts are set equal to each other.

7. The cap nut (3) is rotated by hand tightening by an operator to create a pre-assembled state in which there is no gap in the axial direction between the joint body (1), the cap nut (3), and the sleeve (7), and then 7. The pipe joint according to claim 6, wherein the pipe joint can be brought into a connection-completed state by rotating the cap nut (3) approximately one turn using a power tool.

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