Tubing joint

Abstract: A tubing joint (10) includes a ring claw (112) formed into a zigzag shape with alternating outer notch sections (113) and inner notch sections (115), said ring claw (112) including a plurality of outer ring sections (117), a plurality of inner ring sections (119) each of which is provided between adjacent outer ring sections (117), and a plurality of connecting sections (120) each of which connects an end of the inner ring section (119) with an end of the outer ring section (117). The outer notch sections (113) are of substantially U-shape, and inner edges (120a) of adjacent connecting sections (120), which mutually face and form each U-shaped outer notch section (113), are arranged parallel and substantially perpendicular to the outer edge (A) of the ring claw (112).

Description: The present invention relates to a tubing joint according to the preamble of claim 1. Many types of tubing joints are used for connecting tubes with pressure equipments. A conventional tubing joint 100, which has been widely used (see for instance EP-A-0160559), is shown in Fig. 6: a front sectional view. Constitution of the conventional tubing joint 100 will be explained with reference to Fig. 6. A cylindrical joint proper 102 has a screw section 104, which is provided to a left end section, and which is capable of fixing the tubing joint 100 to a pressure equipment (not shown). The joint proper 102 is made by cutting, so it is generally made of a metal whose cutting machinability is high, e.g., brass. A left end section of a guide cylinder section 106 is inserted in a right end section of the joint proper 102, and fixed therein by caulking. The guide cylinder section 106 is also made of the metal whose cutting machinability is high, e.g., brass. A ring stopper 108 is also made of the metal whose cutting machinability is high, e.g., brass. The stopper 108 is fixed in the left end section of the guide cylinder section 106 by caulking. A release cylinder 110 is made of a plastic. The release cylinder 110 is slidably fitted in the right end section of the guide cylinder section 106, and capable of moving in the axial direction. A ring claw 112 is made of a thin (about 0.2 mm) metal plate, e.g., phosphor bronze, having enough elasticity. The ring claw 112 is provided, on the right side of the stopper 108, in the guide cylinder section 106. As shown in Fig. 7, the ring claw 112 has a plurality of V-shaped outer notch sections 113, which are radially formed from the outer edge toward a center, and a plurality of inner notch sections 115, which are radially formed from an inner edge toward the outer edge. The outer notch sections 113 and the inner notch sections 115 are alternately arranged, in the circumferential direction, to form the ring claw 112 into a zigzag ring shape. An outer edge of the ring claw 112 is bent in the direction of tube-insertion (leftward) and held in a ring groove 106a formed in the guide cylinder section 106 (see Fig.8). The inner edge of the ring claw 112 is capable of biting an outer circumferential face of a tube 130 (see Fig. 8) ,which has been inserted in the joint proper 102, to prevent the tube 130 from moving in the direction of tube-draw (rightward). When the release cylinder 110 is pushed into the guide cylinder section 106, the inner edge of the ring claw 112 is pushed toward the stopper 108 by an inner end of the release cylinder 110, so that the inner edge of the ring claw 112 releases the tube 130. By releasing the tube 130, the tube 130 can be pulled out from the tubing joint 100. A seal ring 116, which is made of rubber, tightly contacts the outer circumferential face of the tube 130 so as to prevent fluid from leaking therefrom. However, the conventional tubing joint 100 has a following disadvantage. When pressurized fluid is introduced into the plastic tube 130 which has been attached to the pressure equipment, outer diameter of the tube 130 is changed according to change of fluid pressure. By changing the fluid pressure in the tube 130, external force from the tube 130, whose magnitude continuously changes, always works to the inner edge of the ring claw 112. Namely, the inner edge of the ring claw 112 is always moved in the direction of an arrow X (see Fig. 8). On the other hand, the outer edge of the ring claw 112 contacts an inner face of the ring groove 106a of the guide cylinder section 106, so its movement is limited. With this structure, the V-shaped spaces or the V-shaped outer notch sections 113 are opened and closed when the inner edge of the ring claw 112 is moved in the direction of the arrow X. If a specific V-shaped outer notch section 113 is opened and closed, stress concentration is repeated in the specific outer notch section 113, so that cracks 114 is made in parts corresponding to innermost parts of the specific outer notch section 113 (see Fig. 7). Then the ring claw 112 will be broken along the cracks 114. An object of the present invention is to provide a tubing joint having a long span of life, in which stress concentration can be avoided even if external force from the tube repeatedly works to the ring claw. To achieve the object, the tubing joint of the present invention comprises the features of claim 1. In the present invention, the inner edges of the adjacent connecting sections, which mutually face and form each U-shaped outer notch section, are arranged parallel and substantially perpendicular to the outer edge of the ring claw. So external force, which is caused by pressure change in the tube, is vertically transmitted to the ring groove via the connecting sections and the outer ring sections, so that the external force does not act the force opening and closing the U-shaped outer notch sections. With this structure, the stress concentration in the connecting sections can be prevented, and the span of life of the ring claw or the tubing joint can be outstandingly extended. Each connecting section has a part of substantially fixed width. By the fixed width part, the stress concentration can be effectively avoided, and the span of life can be further extended. The positions of bending the outer edge of the ring claw may be located along a virtual circular line connecting innermost parts of the inner notch sections. The joint proper may include: a cylindrical base section; and a guide cylinder section whose one end is connected with one end of the cylindrical base section, wherein the ring claw is provided in the guide cylinder section, the release cylinder is slidably fitted in the other end of the guide cylinder section, and the guide cylinder section and the release cylinder are made by drawing metal materials. In the case of making the guide cylinder section and the release cylinder by drawing the metal materials, they can be made in a shorter time than the case of making the same by cutting, so that manufacturing cost of the tubing joint can be reduced. The release cylinder may have a plurality of engage holes, which are formed in an outer circumferential face of an inner part and arranged in the circumferential direction, and each of which is elongated in the axial direction; the guide cylinder section may have a plurality of engage pieces, which are extended radially inward, and which are capable of respectively engaging with the engage holes so as to limit the axial movement of the release cylinder. Further, the engage pieces may be tongue pieces, which are formed by cutting parts of the other end of the guide cylinder section and bending radially inward. The one end of the guide cylinder section may be formed into a large diameter section, which is capable of covering over the one end of the base section, and the outer edge of the ring claw may be held in the ring groove, which is formed between one end face of the base section and an inner face of the large diameter section of the guide cylindrical section. An embodiment of the present invention will now be described by way of examples and with reference to the accompanying drawings, in which: Fig. 1 is a side sectional view of a tubing joint of the embodiment of the present invention; Fig. 2 is a exploded perspective view of the tubing joint shown in Fig. 1; Fig. 3 is a front view of a ring claw shown in Fig. 1; Fig. 4 is a sectional view taken along a line B-B in Fig. 3; Fig. 5 is a partial enlarged view of the ring claw; Fig. 6 is a side sectional view of the conventional tubing joint; Fig. 7 is a front view of the conventional ring claw; and Fig. 8 is a partial sectional view in the vicinity of the ring claw shown in Fig. 7. The preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. Firstly, constitution of a tubing joint 10 will be explained with reference to Figs. 1-4. A base section 12 is formed into a cylindrical shape. A screw section 14, which is capable of screwing with a pressure equipment (not shown) to fix the tubing joint 10 thereto, is formed on an outer circumferential face of a left end section of the base section 12. There is formed a circular groove 16 on an outer circumferential face of a right end section of the base section 12. The base section is made by cutting, so it is generally made of a metal whose cutting machinability is high, e.g., brass. Note that, the right end section of the base section 12, with which a guide cylinder section 18 (described later) is connected, may be a plastic cylinder. The guide cylinder section 18 is made by drawing a stainless steel plate. One end section (a left end section in Figs. 1 and 2) of the guide cylinder section 18 is a large diameter section 20, which is capable of fitting and covering over the outer circumferential face of the right end section of the base section 12. There is formed a circular projection 22, which projects inward to fit in the circular groove 16 of the base section 12, on an inner circumferential face of the large diameter section 20. The circular projection 22 runs round the inner circumferential face, but a plurality of projections may be formed and arranged, in the circumferential direction, on the inner circumferential face. The right end section of the base section 12 is press fitted into the large diameter section 20 to connect the base section 12 with the guide cylinder section 18. On the other hand, there is formed engage pieces 24, which are extended radially inward, in the other end section (a right end section in Figs. 1 and 2) of the guide cylinder section 18. The engage pieces 24 are formed by: cutting parts of the other end section to make a plurality of tongue pieces; and bending left ends of the tongue pieces radially inward. In the present embodiment, the engage pieces 24 are formed by cutting the parts of the other end section in a U-shape so as to form the engage pieces 24 into rectangular shape, but they maybe formed into other shapes: triangular shape, half circle shape, etc.. Free ends of the engage pieces 24 are capable of elastically moving with an arc track. The base section 12 and the guide cylinder section 18 constitute a joint proper 11 in the present embodiment. A release cylinder 26 is made by drawing a stainless steel plate. Outer diameter of the release cylinder 26 is slightly shorter than inner diameter of the right end section of the guide cylinder section 18. The release cylinder 26 is inserted in the right end section of the guide cylinder section 18, and it is capable of sliding in the axial direction therein. The release cylinder 26 has a plurality of engage holes 28, which are formed in an outer circumferential face of a part in the guide cylinder section 18 and which are arranged in the circumferential direction. Number of the engage holes 28 is equal to that of the engage pieces 24. Each engage hole 28 is arranged to respectively engage with the engage pieces 24. The engage holes 28 are elongated in the axial direction. There is formed a flange section 26a at right end of the release cylinder 26. To fit the release cylinder 26 into the guide cylinder section 26, the release cylinder 26 is inserted into the guide cylinder section 18 from its right side. When the the release cylinder 26 is inserted thereinto, the left end section of the release cylinder 26 moves the free ends of the engage pieces 24 radially outward against their elasticity. When the release cylinder 26 is further inserted into the guide cylinder section 18 and the engage holes reach the free ends of the engage pieces 24, the engage pieces 24, which have been elastically moved radially outward, respectively engage with the engage holes 28 by their own elasticity. By engaging the engage pieces 24 with the engage holes 28, the release cylinder 26 can be securely held in the guide cylinder section 18. Since the engage holes 28 are elongated in the axial direction, the axial movement of the release cylinder 26 is limited to the longitudinal length of the engage holes 28. Note that, the engage holes may be provided in the guide cylinder section 18 instead of the engage pieces 24; the release cylinder 26 may have the engage pieces, which is capable of engaging with said engage holes. A ring claw 112 is shown in Figs. 3 and 4. The ring claw 112 is made of a metal ring plate, e.g., stainless steel. The ring claw 112 is made by: forming a plurality of outer notch sections 113, which are radially formed from the outer edge toward a center, and a plurality of inner notch sections 115, which are radially formed from an inner edge toward the outer edge. The outer notch sections 113 and the inner notch sections 115 are alternately arranged to form the ring claw 112 into a zigzag ring shape. By forming into the zigzag ring shape, the ring claw 112 has: a plurality of outer ring sections 117; a plurality of inner ring sections 119, each of which is provided between adjacent outer ring sections 117; and a plurality of connecting sections 120, each of which connects an end of the inner ring section 119 with an end of the outer ring section 117, which corresponds to said end of the inner ring section 119. In the present invention, the outer notch sections 113 are substantially formed into the U-shape, so that inner edges 120a of adjacent connecting sections 120, which mutually face and form each U-shaped outer notch section 113, are arranged parallel and substantially perpendicular to the outer edge A of the ring claw 112. Note that, connecting portions between each outer ring section 117 and each connecting section 120 are made round corners. Each connecting section 120 has a part 120b, which has substantially fixed width (see Fig. 5). Further, it is preferable to make the fixed width part 120b as long as possible. The outer edges of the outer ring sections 117, which have prescribed width, are bent in the direction of tube-insertion or axially inward (see Fig. 4). As clearly shown in Fig. 3, positions C of bending the outer edge of the outer ring sections117 are preferably located along a virtual circular line connecting innermost parts of the inner notch sections 115. The outer edges, which have been bent, of the ring claw 112 are held in a ring groove 30, which is formed between a right end face of the base section 12 (or a right end face of a stopper 32) and an inner end face of the large diameter section 20. The stopper 32 is formed into a tapered ring. The stopper 32 is also made by drawing a stainless steel plate. An outer edge of the stopper 32 is pinched by the right end face of the base section 12 and the inner end face of the large diameter section 20, so that it is fixed in the guide cylinder section 18. When the inner edge (the inner ring sections 119) of the ring claw 112 is pushed axially inward by the end of the release cylinder 26, the inner ring sections 119 or the connecting sections 120 contact a right end face of the stopper 32. By the contact, deformation of the connecting sections 120 are limited so as not to deform beyond their elastic limit. Inner diameter of the stopper 32 is gradually made shorter toward the direction of the insertion of the release cylinder 26. There is provided an elastic seal ring 36, which is made of synthetic rubber, between a first step section 34, which is formed in the base section 12 and the stopper 32. In the tubing joint 10 having above described constitution, a tube 38 is inserted into the joint proper 11 via the release cylinder 26. The tube 38 pushes to move the inner ring sections 119 of the ring claw 112 radially outward against the elasticity of the connecting sections 120. The tube 38 is inserted until its front end contacts a second step section 40 in the base section 12. While the insertion of the tube 38, since the outer edge or the outer ring sections 117 of the ring claw 112 are bent inward, the outer edge or the outer ring sections 117 contact an inner face of the ring groove 30. By the contact, the ring claw 112 is not moved inward together with the tube 38. Since the inner ring sections 119 of the ring claw 112 diagonally contact an outer circumferential face of the tube 38, edges of the inner ring sections 119 bite the outer circumferential face of the tube 38 when the tube 38 is pulled axially outward, so that the tube 38 is securely held in the tubing joint 10. In the case that pressurized fluid is introduced into the tube 38, and outer diameter of the tube 38 is changed by changing the fluid pressure. In this case, the inner ring sections 119 and the connecting sections 120 are repeatedly bent in the direction of the arrow X shown in Fig. 8 by external force from the tube 38 as well as the conventional tubing joint, which has been explained with reference to Fig. 8. When the inner ring sections 119 and the connecting sections 120 are bent, force from the sections 119 and 120 biases the edges of the outer ring sections 117 onto the inner face of the ring groove 30. In the conventional ring claw, as described above, the outer notch sections are formed into the V-shape which is made broader toward outside, so the V-shaped outer notch sections are opened and closed when the edges of the outer ring sections are repeatedly biased onto the inner face of the ring groove. On the other hand, the outer notch sections 113 are substantially formed into the U-shape, and the inner edges 120a of the adjacent connecting sections 120, which mutually face and form each U-shaped outer notch section 113, are arranged parallel and substantially perpendicular to the outer edge of the ring claw 112. With this structure, the external force Y (see Fig. 5) working to the ring groove 30 via the connecting sections 120 and the outer ring sections 117 is perpendicularly directed with respect to contact points in the ring groove 30, so that the external force does not open and close the U-shaped outer notch sections 113. Without opening and closing the U-shaped outer notch sections 113, the stress concentration, which breaks the ring claw of the conventional tubing joint, can be avoided. A rupture test, whose conditions were harder than those according to Japan Industrial Standard, was executed with the conventional ring claw and the ring claw 112 of the present embodiment. The conventional claw was broken until external force was applied about 500,000 times. On the other hand, the ring claw 112 of the present embodiment was not broken in spite of applying the external force more than 1,000,000 times. So the ring claw 112 of the present embodiment has outstanding durability. Note that, by employing the fixed width sections 120b in the connecting sections 120, the force from the inner ring sections 119 is not divided, so the stress concentration can be avoided more effectively. Namely, the durability can be further improved. To detach the tube 38 from the tubing joint 10, the release cylinder 26 is moved axially inward (leftward) to move the inner ring sections 119 of the ring claw 112, so that the edges of the inner ring sections 119 release the tube 38. By releasing the tube 38, the tube 38 can be pulled out from the tubing joint 10. Forming the guide cylinder section 18 and the release cylinder 26 by drawing the metal plates, they can be made in shorter time than the case of making them by cutting. By the drawing, materials which is difficult to cut, e.g., stainless steel, can be employed, so that rusting in the sliding members (the guide cylinder section 18 and the release cylinder 26), which are apt to rust, can be prevented. Without rusting, the life span of the tubing joint 10 can be extended. In the present invention, the joint proper 11 need not have two members: the base section 12 and the guide cylinder section 18, so the two members may be integrally formed as well as the conventional tubing joint.

Claims: A tubing joint (10) comprising a joint proper (11) of substantially cylindrical shape to receive therein a tube (38), a ring claw (112) of resilient material an outer edge of which is bent in the direction of tube-insertion and is held in a ring groove (30) formed in said joint proper (11), said ring claw (112) having a plurality of outer notch sections (113), which extend radially from the outer edge towards the centre thereof, and a plurality of inner notch sections (115), which extend radially from an inner edge towards the outer edge thereof, the outer notch section (113) and the inner notch sections (115) being arranged alternately whereby the ring claw (112) is of a zigzag ring shape, said ring claw (112) further including a plurality of outer ring sections (117), a plurality of inner ring sections (119) each of which is located between adjacent pairs of outer ring sections (117), and a plurality of connecting sections (120) each of which connects one end of an associated inner ring section (119) with one end of an associated outer ring section (117), the inner ring sections (119) of said ring claw (112) being capable of biting into an outer circumferential face of the tube (38) inserted into said joint proper (11) to prevent the tube (38) from moving in the direction of tube-withdrawal, and a release cylinder (26) in said joint proper (11) capable of sliding in the axial direction of the joint to push the inner edge of said ring claw (112) to release the tube (38), characterized in that the outer notch sections (113) are each of substantially U-shape, each connecting section (120) having a radial extent (120b) between neighbouring outer and inner notch sections (113,115) of substantially constant width fixed along the circumference and of a predetermined length, adjacent connecting sections (120), which mutually face one another and form each U-shaped outer notch section (113), being parallel with one another and extending substantially perpendicularly to the outer edge (A) of said ring claw (112). A tubing joint (10) according to claim 1 wherein the bends (C) in the outer edge of said ring claw (112) extend along a virtual circular line connecting the bases of the inner notch sections (115). A tubing joint (10) according to claim 1 or claim 2 wherein said joint proper (11) includes a cylindrical base section (12) and a guide cylinder section (18) one end of which is connected with one end of said cylindrical base section (18), said ring claw (112) being located in said guide cylinder section (18) and said release cylinder (26) being slidably located in the other end of said guide cylinder section (18). A tubing joint (10) according to any one of claims 1 to 3 wherein said release cylinder (26) has a plurality of circumferentially spaced holes (28) formed in an outer circumferential face of an inner part thereof each of which is elongated in the axial direction, said guide cylinder section (18) having a plurality of engage pieces (24) extending radially inwardly thereof for respective engagement with the holes (28) so as to limit axial movement of said release cylinder (26). A tubing joint (10) according to claim 4 wherein said engage pieces are tongue pieces (24) formed by cutting parts of the other end of said guide cylinder section (18) and bending said parts radially inwardly. A tubing joint (10) according to any one of claims 3 to 5 wherein the one end of said guide cylinder section (18) is of a large diameter capable of receiving therein the one end of said base section (12), the outer edge of said ring claw (112) being held in a ring groove (30) formed between one end face of said base section (12) and an inner face of the large diameter one end of said guide cylindrical section (18).

Inventors: HAMA TOMIO, YAMAZAKI KIYOYASU, HAMA, TOMIO, YAMAZAKI, KIYOYASU, Hama, Tomio, c/o K.K. Nihon Pisco, Yamazaki, Kiyoyasu, c/o K.K. Nihon Pisco
Applicants: NIPPON PISCO KK, KABUSHIKI KAISHA NIHON PISCO
Application year: 1996
Main classification: F16L37
IPC codes: F16L37