WO2005024284A1

WO2005024284A1 - Tube coupling

Info

Publication number: WO2005024284A1
Application number: PCT/KR2004/002216
Authority: WO
Inventors: Kyung-Sang Lim
Original assignee: Sang-A Pneumatic Co., Ltd.
Priority date: 2003-09-04
Filing date: 2004-09-02
Publication date: 2005-03-17

Abstract

Disclosed is a tube coupling in which a tube control collet stably works, resilient arms and O-ring are safely protected, and assembly is simple. The tube coupling comprises a tube control collet (204) provided with a tube control collet support (250), which is inserted into a tube coupling body (201). The tube control collet support (250) includes a plurality of extending arms (253a, 253b, 253c and 253d), tube guide projections (256a, 256b, 256c and 256d) formed below the respective extending arms, and slots (252a, 252b, 252c and 252d) between the respective extending arms. When a circle is drawn along the ends of the tube guide projections, it has a diameter greater than an outer diameter of the tube. Resilient arms (243a, 243b, 243c and 243d) of the tube control collet are inserted into the respective slots, and tapered flanges (245a, 245b, 245c and 245d) of the resilient arms (243a, 243b, 243c and 243d) are locked in the edges (255a, 255b, 255c and 255d) formed in the respective slots to prevent the tube from being extracted.

Description

TUBE COUPLING

TECHNICAL FIELD The present invention relates to a tube coupling having a coupling body coupled with a control collet, and more particularly to a tube coupling in which a tube is stably fixed to a tube control collet and its assembly is simple .

BACKGROUND ART Examples of a related art tube coupling include the US Patent No. 5,934,713 and the US Patent No. 5,390,969. The related art tube coupling disclosed in the US Patent No. 5,934,713 will be described with reference to FIG. 1 and FIG. 2. The related art tube coupling includes a coupling body 1, an O-ring 2 inserted into the coupling body 1, and a tube control collet 4 controlling a tube 3 to be coupled with or extracted from the coupling body 1. The tube control collet 4 includes an annular sleeve 42 having a grip 41 at the outer side, a plurality of resilient arms 43a, 43b, and 43c extended from one end of the annular sleeve 42, teeth 44a, 44b, and 44c axially projecting toward the annular sleeve at the inner side of each resilient arm, and flanges 45a, 45b and 45c provided at the outer side of each resilient arm. The respective flanges are respectively provided with inclined cam faces 46a, 46b, and 46c in a direction opposite to an insertion direction of the tube 3. Slots 11a and lib are provided in the vicinity of the inlet of the coupling body 1. The flanges 45a, 45b, and 45c are inserted into the slots 11a and lib. The slots 11a and lib have the size that allows the flanges 45a, 45b and 45c to flexibly move at a predetermined distance. The tube coupling is assembled in such a manner that the O-ring 2 and the tube control collet 4 are sequentially inserted into the coupling body 1. Once the tube 3 is inserted into the assembled tube coupling, the resilient arms 43a, 43b, and 43c of the tube control collet 4 are outwardly pushed by the outer surface of the tube and the end of the tube 3 is moved to the position of the O-ring 2. The projecting teeth 44a, 44b, and 44c formed at the resilient arms abut the outer surface of the tube 3 so that the resilient arms are outwardly pushed and radially extended . Once the tube is forcibly pulled by external force in a state that the tube is inserted into the tube coupling, it is outwardly moved together with the tube control collet 4 because the tube 3 is engaged with the teeth 44a,

44b and 44c. The tube control collet 4 is moved until the inclined cam faces 46a and 46b are locked in the end of the slots 11a and lib. Once the tube continues to be forcibly pulled by external force in a state that the inclined cam faces 46a and 46b are locked in the end of the slots 11a and lib, the teeth 44a, 44b, and 44c are axially tightened by action of the inclined cam faces 46a and 46b to pressurize the tube 3. Finally, the tube cannot be extracted from the tube coupling. Under the circumstances, the tube 3 can forcibly be extracted from the tube coupling in a state that the grip 41 of the tube control collet 4 is tightly pushed to the insertion direction of the tube. Another related art tube coupling disclosed in the US Patent No. 5,390,969 will be described with reference to FIG. 3 and FIG. 4. The second related art tube coupling includes a tube control collet 104. The tube control collet 104 includes a cylindrical portion 142 having a grip 141, a plurality of resilient arms 143a and 143b extended from one end of the cylindrical portion 142, teeth 144a and 144b axially projecting toward the cylindrical portion at the inner side of each resilient arm, and flanges 145a and 145b provided at the outer side of each resilient arm. A tube coupling body 101 has a cylindrical shape and includes an annular spaced portion 121 therein. Some of the resilient arms 143a and 143b and the flanges 145a and 145b are inserted into the annular spaced portion 121. The annular spaced portion 121 includes an inner edge portion 122 locking O-ring 2 and an outer edge portion 123 locking the flanges 145a and 145b so as not to allow the tube control collet to be extracted. The distance between the edge portions 122 and 123 is set in such a manner that the flanges 145a and 145b can move at a predetermined distance within the coupling body 101 when the resilient arms 143a and 143b are inserted into the coupling body 101. Tapered portions 146a and 146b are formed from the inner edge portion 122 to the outer edge portion 123 at the head portion of the annular spaced portion 121 in a direction opposite to an insertion direction of the tube 3. Once the tube 3 is inserted into the aforementioned tube coupling, the resilient arms 143a and 143b of the tube control collet 104 are outwardly pushed by the outer surface of the tube and the end of the tube 3 is moved to the position of the O-ring 2. The teeth 144a and 144b more inwardly projected than the resilient arms abut the outer surface of the tube 3 so that the resilient arms are outwardly pushed and radially extended. Once the tube is forcibly pulled by external force in a state that the tube is inserted into the tube coupling, it is moved together with the tube control collet 104 because the tube 3 is engaged with the teeth 144a and 144b. The tube control collet 104 and the tube are moved until the flanges 145a and 145b are locked in the tapered portions 146a and 146b. Once the tube continues to be forcibly pulled by external force in a state that the flanges 145a and 145b abut the tapered portions 146a and 146b, the resilient arms 143a and 143b are axially tightened by action of the tapered portions 146a and 146b to pressurize the tube 3. Once the flanges 145a and 145b are locked in the outer edge portion 123 of the coupling body 101, the tube control collet 104 is not outwardly moved any longer even though the external force is applied thereto. Under the circumstances, the tube 3 can forcibly be extracted from the tube coupling in a state that the grip 141 of the tube control collet 104 is tightly pushed to the insertion direction of the tube. The aforementioned related art tube couplings have several problems. The tube control collet is likely to be extracted from the coupling body. Thus, the tube control collet is more likely to be extracted from the coupling body by any external impact given thereto due to its movement or rotation . Further, if the tube remains bent at a right angle to the central axis for a long time, distorted force acts on the resilient arms. For this reason, resilient deviation of the resilient arms is caused. Particularly, since the annular spaced portion is provided in the tube coupling body in the second related art tube coupling, the tube coupling body cannot be molded by ejection at once. For the structure of the second tube coupling body, the coupling body is divided into two parts around an abutting portion of the annular spaced portion and the two parts are separately molded by ejection. Then, the two parts should be jointed to each other by welding in the assembly process as shown in FIG. 5. Alternatively, two parts should be jointed to each other by screw as shown in FIG. 6.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings: Fig. 1 is a sectional view illustrating a related art tube coupling; FIG. 2 is a sectional view illustrating a tube control collet coupled to a coupling body of FIG. 1; FIG. 3 is a sectional view illustrating another related art tube coupling; FIG. 2 is a sectional view illustrating a tube control collet coupled to a coupling body of FIG. 3; FIG. 5 and FIG. 6 illustrate examples of manufacturing a tube coupling body of FIG. 3; FIG. 7 is an exploded perspective view of a tube coupling according to the first embodiment of the present invention; FIG. 8 is a cut-sectional view of FIG. 7; FIG. 9 is a plane view illustrating a tube control collet for a tube coupling according to the first embodiment of the present invention; FIG. 10 is a plane view illustrating a tube control collet support for a tube coupling according to the first embodiment of the present invention; FIGS. 11 to 14 are sectional views illustrating the operation of a tube coupling according to the first embodiment of the present invention; FIG. 15 is an elevational view illustrating an example of a structure of a tube control collet support and a tube coupling body formed in a single body in accordance with the first embodiment of the present invention; FIG. 16 is a cut-sectional view of FIG. 10; FIG. 17 is an elevational view illustrating another example of a tube control collet for a tube coupling in accordance with the first embodiment of the present invention; FIG. 18 is an elevational view illustrating another example of a tube control collet support for a tube coupling in accordance with the first embodiment of the present invention; FIG. 19 is an exploded perspective view of a tube coupling according to the second embodiment of the present invention; FIG. 20 is a cut-sectional view of FIG. 19; FIG. 21 is a plane view illustrating a tube control collet for a tube coupling according to the second embodiment of the present invention; FIG. 22 is a plane view illustrating a tube control collet support for a tube coupling according to the second embodiment of the present invention; FIG. 23 is a cut-sectional view illustrating the state that a tube control collet for a tube coupling according to the second embodiment of the present invention is fixed a tight cap; FIGS. 24 to 26 are sectional views illustrating the operation of a tube coupling according to the second embodiment of the present invention; FIG. 27 is an exploded prospective view illustrating another example of a tube coupling according to the second embodiment of the present invention; FIG. 28 is a cut-sectional view of FIG. 27; FIG. 29 is an exploded prospective view illustrating other example of a tube coupling according to the second embodiment of the present invention; and FIG. 30 is a cut-sectional view of FIG. 29.

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL PROBLEMS Accordingly, the present invention is directed to a tube coupling that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. The tube coupling provides a tube control collet support coupled to a coupling body and a tube control collet having a plurality of resilient arms, inserted into the tube control collet support.

TECHNICAL SOLUTIONS To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a tube coupling according to the first embodiment of the present invention comprises a tube control collet support including resilient arms of a tube control collet and tube guide projections disposed between the resilient arms. The tube guide projections act uniformly resiliency of the resilient arms on the surface of the tube and guide insertion of the tube. The ends of the tube guide projections are positioned more outwardly than those of teeth formed in the resilient arms of the tube control collet around the central axis of the tube coupling in a state that the tube is not inserted into the coupling body. Once the tube is inserted into the coupling body, the ends of the tube guide projections and the ends of the teeth together support the outer surface of the tube. In other words, the ends of the teeth of the resilient arms holding the tube are not moved more outwardly than those of the tube guide projections even though any external force is given to the tube inserted into the tube coupling. Thus, the resilient arms are stably maintained. The tube control collet support for the tube coupling according to the first embodiment of the present invention may be provided in a single body with the tube coupling body or may separately be provided apart from the tube coupling body. The tube control collet support separately provided apart from the tube coupling body includes a plurality of extending arms extended from one end of a cylindrical portion and slots formed between the respective extending arms, and tube guide projections linearly formed inside the extending arms along the insertion direction of the tube. The slots serve as spaces where the resilient arms of the tube control collet are slidingly moved when the tube control collet is inserted into the tube control collet support. Edges are formed in the slots as the boundary between the slots and the cylindrical portion. The edges serve to clamp the tube control collet so as not to be outwardly extracted and tight the resilient arms toward the central axis of the tube when the flanges of the resilient arms are disposed at the position of the edges. Locking projections inserted into the coupling body are formed at the outside of the cylindrical portion of the tube control collet support. To further achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a tube coupling according to the second embodiment of the present invention comprises a tube control collet support tightly fixed to a coupling body by tightening of a tight cap coupled to the couplind body, the tube control collet support including resilient arms of a tube control collet and tube guide projections disposed between the resilient arms. The tube guide projections act uniformly resiliency of the resilient arms on the surface of the tube and guide insertion of the tube. The ends of the tube guide projections are positioned more outwardly than those of teeth formed in the resilient arms of the tube control collet around the central axis of the tube coupling in a state that the tube is not inserted into the coupling body. Once the tube is inserted into the coupling body, the ends of the tube guide projections and the ends of the teeth together support the outer surface of the tube. In other words, the ends of the teeth of the resilient arms holding the tube are not moved more outwardly than those of the tube guide projections even though any external force is given to the tube inserted into the tube coupling. Thus, the resilient arms are stably maintained. The tube control collet support separately provided apart from the tube coupling body includes a plurality of extending arms extended from one end of a cylindrical portion and slots formed between the respective extending arms, and tube guide projections linearly formed inside the extending arms along the insertion direction of the tube. The slots serve as spaces where the resilient arms of the tube control collet are slidingly moved when the tube control collet is inserted into the tube control collet support. Edges are formed in the slots as the boundary between the slots and the cylindrical portion. The edges serve to clamp the tube control collet so as not to be outwardly extracted and tight the resilient arms toward the central axis of the tube when the flanges of the resilient arms are disposed at the position of the edges. A clamp for the tight cap and locking projections inserted into the coupling body are formed at the outside of the cylindrical portion of the tube control collet support. The slots into which the locking projections of the control collet support are inserted have the size that allows the locking projections to move at a certain interval. The tube coupling body of the second embodiment includes a thread coupled to the tight cap and tapered portions abutting the flanges formed in the resilient arms of the tube control collet. The tapered portions are provided so that the tube control collet support is tightly coupled to the coupling body and the flanges of the tube control collet are slid and retracted when the tight cap is tightened to the coupling body. Since the flanges abutting the tapered portions of the coupling body are retracted to tightly push the tube control collet support to the coupling body, the outer surface of the tube is strongly tightened. As a result, the tube control collet is locked unmoved. Edges are formed at the boundary between the slots of the tube control collet support and the cylindrical portion. Tapered portions are formed in the flanges of the resilient arms of the tube control collet. The tapered portions formed in the flanges abut the edges of the tube control collet support when the flanges are tightened along the tapered portions formed in the coupling body. To extract forcibly the tube from the coupling body, after the tight cap is unlocked to release the flanges of the tube control collet from the tapered portions of the coupling body, the tube control collet is tightly pushed to the insertion direction of the tube. In this case, the tube can be extracted from the coupling body. Accordingly, an object of the present invention is to provide a tube coupling in which a tube control collet stably works. Another object of the present invention is to provide a tube coupling in which a tube is not extracted after it is inserted into a coupling body and resiliency of resilient arms uniformly acts on the tube. Other object of the present invention is to provide a tube coupling that facilitates assembly of its parts.

APPLICABLE ADVANTAGES The tube coupling according to the present invention has the following advantages. A tube control collet 204 for a tube coupling according the first embodiment of the present invention is provided with a tube control collet support 250 to be coupled to a tube coupling body 201. The tube control collet support 250 includes extending arms 253a, 253b, 253c and 253d, tube guide projections 251a, 251b, 251c and 251d formed below the extending arms, and slots 252a, 252b, 252c and 252d formed between the respective extending arms. When a virtual circle is drawn along the ends of the tube guide projections, it has a diameter greater than an outer diameter of the tube. The resilient arms 243a, 243b, 243c and 243d of the tube control collet are inserted into the respective slots, and flanges 245a, 245b, 245c and 245d of the resilient arms 243a, 243b, 243c and 243d are locked in the edges 255a, 255b, 255c and 255d formed in the respective slots to prevent the tube from being extracted. A tube control collet support 350 for a tube coupling according to the second embodiment of the present invention is tightly fixed to a tube coupling body by tightening of a tight cap 366 coupled to the tube coupling body 301. The tube control collet support 350 separately provided apart from the coupling body 301 includes a plurality of extending arms 353a, 353b, 353c and 353d extended from one end of a cylindrical portion 354, slots 352a, 352b, 352c and 352d formed between the respective extending arms, and tube guide projections 351a, 351b, 351c and 351d linearly formed inside the extending arms in the same direction as the insertion direction of the tube. The slots serve as spaces where resilient arms of the tube control collet are slidingly moved when the tube control collet is inserted into the tube control collet support. Edges 355a, 355b, 355c and 355d formed inside the slots serve to clamp the control collet so as not to be outwardly extracted and tight the flanges 345a, 345b, 345c and 345d toward the central axis of the tube when the flanges 345a, 345b, 345c and 345d of the resilient arms are disposed at the position of the edges. Meanwhile, the tube coupling body 301 is provided with a thread 333 jointed to the tight cap 366. A tapered portion 388 abutting the flanges 345a, 345b, 345c, and 345d formed in the resilient arms of the tube control collet is formed in the vicinity of the inlet of the tube coupling body 301. The tapered portion 388 serves to retract the flanges of the tube control collet as the tube control collet support is tightly pushed to the coupling body when the tight cap is tightened in the coupling body. The tight cap 366 serves to simultaneously lock the flanges 345a, 345b, 345c and 345d of the tube control collet in the tapered portion 388 and the edges 355a, 355b, 355c and 355d of the tube control collet support. In the tube coupling according to the first and second embodiments of the present invention, the tube control collet can stably work in the coupling body and the tube can firmly be locked in the coupling body. Further, resiliency of the resilient arms of the tube control collet can uniformly be provided by means of action of the tube guide projections 351a, 351b, 351c and 351d. The tube coupling having a simple assembly structure can be obtained. Moreover, since the tube guide projections 351a, 351b, 351c and 351d prevent a tube having a size greater than the standard size from being inserted into the coupling body and exactly guide the tube, the resilient arms, the teeth, and O-ring can safely be protected. While the present invention has been described and illustrated herein with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention that come within the scope of the appended claims and their equivalents. BEST MODE FOR CARRYING OUT THE INVENTION A tube coupling comprising a tube control collet inserted into a coupling body 201 of a tube, the tube control collet including a plurality of resilient arms 243a, 243b, 243c and 243d extended from one end of a cylindrical portion 242 and flanges 245a, 245b, 245c and 245d provided at the outer side of each resilient arm, movement in an extraction direction of the tube 3 inserted into the tube coupling body being stopped by tightening of the flanges and the resilient arms being pushed to an insertion direction of the tube to control tightening of the flanges, wherein the tube coupling body comprises a tube control collet support 250 guiding movement of the tube control collet, and the tube control collet support includes at least one or more tube guide projections 256a, 256b, 256c and 256d disposed between the respective resilient arms of the tube control collet. The tube guide projection of the tube control collet support is formed inside one selected from a plurality of extending arms 253a, 253b, 253c and 253d extended from a cylindrical portion 254, and the tube control collet 204 is inserted into the cylindrical portion 254 of the tube control collet support to move the flanges of the tube control collet in slots 252a, 252b, 252c and 252d between the respective extending arms. The tube guide projections are provided in the respective extending arms one to one. The flanges 245a, 245b, 245c and 245d of the resilient arms are respectively locked in edges 255a, 255b, 255c and 255d formed at the boundary between the cylindrical portion and the slots to control tightening of the tube, and the flanges abutting the edges are provided with tapered portions 246a, 246b, 246c and 246d formed toward the extraction direction of the tube. The tube control collet support is provided with locking projections 251a and 251b on the outer surface, and the locking projections are inserted into slots 211a and 211b formed in the tube coupling body. The flanges of the resilient arms are provided with teeth 244a, 244b, 244c and 244d on the lower surface, and the ends of the teeth are projected much more than the ends of the tube guide projections in a state that the tube is not inserted into the coupling body. The tube guide projections are linearly formed along the insertion direction of the tube. The resilient arms of the tube control collet are formed to correspond to the extending arms of the tube control collet support one to one. O-ring is inserted between an inner end of the tube control collet support and an inner edge 22 formed in a through hole in the tube coupling body. The tube control collet support 250 guiding movement of the tube control collet 204 is inserted into the tube coupling body 201, and the tube control collet support includes a cylindrical portion 254, a plurality of extending arms 253a, 253b, 253c and 253d extended from one end of the cylindrical portion, and slots 252a, 252b, 252c and 252d between the extending arms 253a, 253b, 253c and 253d, guiding the flanges 245a, 245b, 245c and 245d through the cylindrical portion. A tube coupling comprising a tube control collet 304 inserted into a coupling body 301 of a tube, the tube control collet including a plurality of resilient arms

343a, 343b, 343c and 343d extended from one end of a cylindrical portion 342 and flanges 345a, 345b, 345c and 345d provided at the outer side of each resilient arm, movement in an extraction direction of the tube inserted into the tube coupling body being stopped by tightening of the flanges and the resilient arms being pushed to an insertion direction of the tube to control tightening of the flanges, wherein the tube coupling body comprises a tube control collet support 350 guiding movement of the tube control collet, the tube control collet support being fixed to a tight cap 366 coupled with the coupling body, and the flanges 345a, 345b, 345c and 345d of the tube control collet inserted into the tube control collet support are tightened along a tapered portion 388 formed in the coupling body. The tube control collet support includes at least one or more tube guide projections 356a, 356b, 356c and 356d disposed between the resilient arms of the tube control collet. The tube guide projections of the tube control collet support are formed inside one selected from a plurality of extending arms 353a, 353b, 353c and 353d extended from a cylindrical portion 354, and the tube control collet 304 is inserted into the cylindrical portion 354 of the tube control collet support to move the resilient arms of the tube control collet in slots formed between the respective extending arms. Edges 355a, 355b, 355c and 355d are formed at the boundary between the cylindrical portion and the slots of the tube control collet support, and tapered portions 346a, 346b, 346c and 346d are formed in the flanges 345a, 345b, 345c and 345d of the resilient arms of the tube control collet and abut the edges of the tube control collet support when the flanges are tightened along the tapered portion 388 formed in the coupling body. The tapered portions of the flanges of the tube control collet are formed toward the extraction direction of the tube. The tight cap includes an annular projection 367 on the inner surface, and the annular projection is inserted into a clamp 380 for the tight cap, which is formed on the outer surface of the cylindrical portion of the tube control collet support. The tube control collet support is provided with locking projections 351a and 351b on the outer surface, and the locking projections are inserted into slots 311a and 311b formed in the tube coupling body to flexibly move therein . Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. First Embodiment A tube coupling according to the first embodiment of the present invention will be described with reference to FIG. 7 to FIG. 18. The tube coupling according to the first embodiment of the present invention includes a tube coupling body 201, O-ring 2, a tube control collet 204, and a tube control collet support 250. The tube coupling body 201 includes a through hole having an inner edge 222 in which the O-ring is locked. Slots 211a and 211b are formed at a predetermined position between the inlet of the through hole and the edge 222. Locking projections 251a and 251b of the tube control collet support are respectively inserted into the slots 211a and 211b. The tube control collet support 250 includes a cylindrical portion 254 inserted into the inlet portion of the coupling body, a plurality of extending arms 253a, 253b, 253c and 253d extended from one end of the cylindrical portion, and slots 252a, 252b, 252c and 252d between the extending arms 253a, 253b, 253c and 253d. Linear tube guide projections 256a, 256b, 256c and 256d projecting in the same direction as that of the extending arms are provided in the inner surface of the respective extending arms . The tube guide projections are tapered toward the central axis of the tube coupling to substantially form a triangle shape. Meanwhile, the tube control collet 204 includes a cylindrical portion 242 having a grip 241, a plurality of resilient arms 243a, 243b, 243c and 243d extended from the end of the cylindrical portion, flanges 245a, 245b, 245c and 245d formed at the end of each resilient arm, teeth 244a, 244b, 244c and 244d respectively provided below the flanges, and tapered portions 246a, 246b, 246c and 246d formed on the flanges and tapered toward the cylindrical portion from the projecting flanges. A separate flange edge is provided at the rear end of the tapered portions so that the tube control collet cannot be extracted from the tube coupling body. The tube coupling body 201, the tube control collet support 250, and the tube control collet 204 are assembled by being inserted into one another. The assembly process will be described in more detail. The O-ring 2 is inserted into the through hole of the tube coupling body 201 and pushed to be locked in the inner edge 222. The extending arm of the tube control collet support 250 is directed toward the through hole of the tube coupling body in a state that the O-ring is inserted into the through hole, so that it is inserted into the tube coupling body 201. A pair of locking projections 251a and 251b symmetrically formed on the outer surface of the tube control collet support are forcibly inserted into the slots 211a and 211b formed in the tube coupling body. Thus, the locking projections 251a and 251b are firmly fixed to the slots 211a and 211b. Once the tube control collet support is coupled to the tube coupling body, the end of the respective extending arm having the tube guide projection is tightly pushed so that the O-ring is firmly fixed to the through hole in the tube coupling body. After the tube control collet support 250 is coupled to the tube coupling body 201, the tube control collet 204 is inserted into the tube control collet support 250. The respective flanges 245a, 245b, 245c and 245d of the tube control collet are inserted into respective slots 252a, 252b, 252c and 252d formed between the extending arms 253a, 253b, 253c and 253d so that the respective flanges can move at a certain interval . The operation of the aforementioned tube coupling according to the first embodiment of the present invention will be described in more detail with reference to FIG. 11 to FIG. 14. The tube coupling into which no tube is inserted has a sectional structure of FIG. 11. The tube guide projections 256a and 256c of the tube control collet support 250 have a virtually arc-shape around the end with a diameter greater than that of the tube. While the end of the teeth 244a and 244c provided in the resilient arms of the tube control collet 204 have a virtually arc-shape with a diameter smaller than that of the tube . Once the tube is inserted into the cylindrical portion of the tube control collet, as shown in FIG. 12, the resilient arms do not work at the portion of the resilient arms where the teeth 244a and 244c are positioned . Once the tube is pushed to the inner side in a state that the end of the tube 3 is positioned at the teeth of the resilient arms, the resilient arms are outwardly pushed because the virtually arc-shaped diameter of the teeth is smaller than that of the tube. Once the tube is completely pushed, the end of the tube is inserted into the tube coupling body through the O-ring 2 as shown in FIG. 13. The O-ring 2 tightly abuts the outer surface of the tube 3 so as not to outwardly leak fluid flowing through the tube and the tube coupling body. Meanwhile, once the inserted tube 3 is forcibly pulled in a direction opposite to insertion of the tube, the tube control collet 204 is drawn out together with the tube 3 by the teeth 244a and 244c. When the tapered portions 246a and 246c formed in the resilient arms are locked in the inner edges 255a and 255c of the slots of the tube control collet support 250, the teeth are tightened toward the tube 3 as shown in FIG. 14 by action of the tapered portions. As a result, the tube 3 is not extracted from the coupling body. Since the edges of the flanges 245a, 245b, 245c and 245d are sufficiently high, the tube control collet 204 is not extracted from the tube coupling body. The tube 3 can forcibly extracted from the tube coupling body without any difficulty in a state that the tube control collet is tightly pushed to the tube control collet support. Particularly, in the first embodiment of the present invention as will be aware of it from FIG. 11 to FIG. 14, the tube guide projections 256a, 256b, 256c and 257d are linearly formed in the tube control support 250 in parallel with the resilient arms. The tube guide projections are extended more inwardly at the front than the teeth when viewed from the insertion direction of the tube. In this case, the inserting tube can exactly be guided to the teeth. Further, the tube guide projections guide the tube to uniformly act resiliency of the resilient arms on the tube even though the tube is curved. Since the tube having a diameter greater than the standard size is first locked in the tube guide projections, the resilient arms, the teeth, and the O-ring can safely be protected. In the tube coupling according to the first embodiment of the present invention, it is desirable that the tube control collet support 250 is separately provided in view of ejection and assembly of the respective elements. However, the tube coupling body and the tube control collet may be provided in a single body as shown in FIG. 15 and FIG. 16. Once the tube control collet support and the tube coupling body are formed in a single body, an annular groove should be formed in the tube coupling body. Therefore, the tube coupling body formed in a single body with the tube control collet support is molded by ejection using a plastic material, the coupling body is divided into two parts by the structure of ejection molding and then the two parts are molded by ejection. The two parts should be jointed to each other by well-known welding in the assembly process. Alternatively, the two parts should be jointed to each other by screw. In the first embodiment of the present invention, four resilient arms of the tube control collet 204 are provided and four slots and four extending arms are respectively provided in the tube control collet support 250 so that the resilient arms are coupled to the slots one to one. However, the number of the resilient arms, the slots, and the extending arms could properly be adjusted. As an example, the tube control collet 204 and the tube control collet support may be provided as shown in FIGS. 17 and 18. FIG. 17 illustrates a tube control collet having two resilient arms 243a and 243b. FIG. 18 illustrates a tube control collet support having two extending arms 253a and 253b. It is not necessary that the teeth and the tube guide projections are provided in the resilient arms and the extending arms one to one. They may be provided alternately in the resilient arms and the extending arms. Second Embodiment A tube coupling according to the second embodiment of the present invention will be described with reference to FIG. 19 to FIG. 30. The tube coupling according to the second embodiment of the present invention includes a tube coupling body 301, 0-ring 2, a tube control collet 304, a tube control collet support 350, and a tight cap 366. The tube coupling body 301 includes a through hole having an inner edge 322 in which the 0-ring is locked. Slots 311a and 311b are formed at a predetermined position between the inlet of the through hole and the edge 322. Locking projections 351a and 351b of the tube control collet support 350 are respectively inserted into the slots 311a and 311b. A tapered portion 388 tapered in a direction opposite to the inlet of the tube coupling body 301 is annularly provided in the vicinity of the inlet of the tube coupling body 301. A thread 333 is provided on the outer surface of the inlet and is jointed to the tight cap 366 by screw. The tube control collet support 350 includes a cylindrical portion 354 inserted into the tight cap 366, a plurality of extending arms 353a, 353b, 353c and 353d extended from one end of the cylindrical portion, and slots 352a, 352b, 352c and 352d between the respective extending arms 353a, 353b, 353c and 353d. Linear tube guide projections 356a, 356b, 356c and 356d projecting in the same direction as that of the extending arms are provided in the inner surface of the respective extending arms. The tube guide projections are tapered toward the central axis of the tube coupling to substantially form a triangle shape. A clamp 380 for the tight cap is provided on the outer surface of the cylindrical portion 354 of the tube control collet support. The clamp 380 includes an end edge 377, and a plurality of clamp projections 378a and 378b spaced apart from the end edge 377. The clamp projections are provided a tapered portion so as to allow an annular projection 367 of the tight to be easily inserted into the clamp 380 when the cylindrical portion 354 is inserted into the tight cap as shown in FIG. 23. Meanwhile, the tube control collet 304 includes a cylindrical portion 342 having a grip 341, a plurality of resilient arms 343a, 343b, 343c and 343d extended from the end of the cylindrical portion, flanges 345a, 345b, 345c and 345d formed at the end of each resilient arm, teeth 344a, 344b, 344c and 344d respectively provided below the flanges, and tapered portions 346a, 346b, 346c and 346d formed on the flanges and tapered toward the cylindrical portion from the projecting flanges. A separate flange edge is provided at the rear end of the tapered portions so that the tube control collet cannot be extracted from the tube coupling body. The tube coupling body 301, the tube control collet support 350, the tight cap 366, and the tube control collet 304 are assembled by being inserted into one another . The assembly process will be described in more detail, The O-ring 2 is inserted into the through hole of the tube coupling body 301 and pushed to be locked in the inner edge 322. Meanwhile, the tube control collet support 350 is inserted into the tight cap 366 so that the annular projection 367 is fixed to the clamp 380 formed in the cylindrical portion 354 of the tube control collet. Subsequently, the locking projections 351a and 351b of the tube control collet are inserted into the slots 311a and 311b of the tube coupling body into which the 0- ring is inserted. In this case, the slots 311a and 311b have the size that allows the locking projections to flexibly move, thereby moving the tube control collet support 350 at a predetermined distance in a movement direction of the tube. After the tube control collet support 350 coupled with the tight cap 366 is coupled to the tube coupling body 301, the tube control collet 304 is inserted into the cylindrical portion 354 of the tube control collet support 350. The respective flanges 345a, 345b, 345c and 345d of the tube control collet are respectively inserted into the slots 352a, 352b, 352c and 352d formed between the respective extending arms 353a, 353b, 353c and 353d so that the respective flanges can move at a certain interval The operation of the aforementioned tube coupling according to the second embodiment of the present invention will be described in more detail with reference to FIG. 24 to FIG. 26. The tube coupling into which no tube is inserted has a sectional structure of FIG. 24. The tube guide projections 356a and 356c of the tube control collet support 350 have a virtually arc-shape around the end with a diameter greater than that of the tube. While the end of the teeth 344a and 344c provided in the resilient arms of the tube control collet 304 have a virtually arc-shape with a diameter smaller than that of the tube . Once the tube is inserted into the cylindrical portion of the tube control collet, the resilient arms are outwardly pushed because the virtually arc-shaped diameter of the teeth is smaller than that of the tube. Once the tube is completely pushed, the end of the tube is inserted into the tube coupling body through the O-ring 2 as shown in FIG. 25. The O-ring 2 tightly abuts the outer surface of the tube 3 so as not to outwardly leak fluid flowing through the tube and the tube coupling body. In FIG. 25, once the tight cap 366 is tightened toward the tube coupling body 301, the tube control collet support 350 is moved to the tube coupling body together with the tight cap. At this time, the tapered portions 346a and 346c formed in the flanges 345a and 345c are locked in the inner edges 355a and 355c of the tube control collet support 350. As a result, the tapered portions 346a and 346c are moved together with the tube control collet support 350. Once the tight cap 366 continues to be tightened toward the tube coupling body 301 to move the tube control collet and the tube control collet support 350 to the tube coupling body, the flanges 345a and 345c of the tube control collet are inwardly retracted along the tapered portion 388 formed in the inlet of the tube coupling body, thereby strongly tightening the outer surface of the tube 3. In a state that the tight cap 366 is completely tightened as shown in FIG. 26, the flanges 345a and 345c of the tube control collet are locked simultaneously in the tapered portion 388 and the edges 355a and 355c of the tube control collet support 350. In this case, the tube control collet 304 cannot be moved. Since the edges of the flanges 345a, 345b, 345c and 345d are sufficiently high, the tube control collet 304 is not extracted from the tube coupling body. To extract forcibly the tube from the tube coupling, after the tight cap 366 is unlocked and the tube control collet support 350 is retracted to release the flanges 345a and 345c of the tube control collet from the tapered portion 388, the tube control collet is tightly pushed to the tube control collet support. In this case, the tube 3 can forcibly be extracted from the tube coupling body without any difficulty. Particularly, in the second embodiment of the present invention as will be aware of it from FIG. 24 to FIG. 26, the tube guide projections 356a and 356b are linearly formed in the tube control support 350 in parallel with the resilient arms. The tube guide projections are extended more inwardly at the front than the teeth when viewed from the insertion direction of the tube. In this case, the inserting tube can exactly be guided to the teeth . Further, the tube guide projections guide the tube to uniformly act resiliency of the resilient arms on the tube even though the tube is curved. Since the tube having a diameter greater than the standard size is first locked in the tube guide projections, the resilient arms, the teeth, and the O-ring can safely be protected. In the second embodiment of the present invention, four resilient arms of the tube control collet 304 have been provided and four slots and four extending arms have been respectively provided in the tube control collet support 350 so that the resilient arms could be coupled to the slots one to one. However, the number of the resilient arms, the slots, and the extending arms could properly be adjusted . It is not necessary that the teeth and the tube guide projections are provided in the resilient arms and the extending arms one to one. They may be provided alternately in the resilient arms and the extending arms. Another example of the tube control collet support for the tube coupling according to the second embodiment of the present invention can be assembled as shown in FIG.

27 and FIG. 28. The tube control collet support 450 shown in FIG. 27 and FIG. 28 has a structure similar to that of FIG. 19 and FIG. 20. The tube control collet support 450 is different from that of FIG. 19 and FIG. 20 in that it has no locking projection coupled to the coupling body. Therefore, no slot into which the locking projection is inserted is required. Other example of the tube control collet support for the tube coupling according to the second embodiment of the present invention can be assembled as shown in FIG. 29 and FIG. 30. The tube control collet support 550 shown in FIG. 39 and FIG. 30 has a structure similar to that of FIG 19 and FIG. 20. The tube control collet support 550 is different from that of FIG. 19 and FIG. 20 in that the ends of extending arms 553a, 553b, 553c, and 553d directly support the O-ring.

Claims

WHAT IS CLAIMED IS: 1. A tube coupling comprising a tube control collet inserted into a coupling body of a tube, the tube control collet including a plurality of resilient arms extended from one end of a cylindrical portion and flanges provided at the outer side of each resilient arm, movement in an extraction direction of the tube inserted into the tube coupling body being stopped by tightening of the flanges and the resilient arms being pushed to an insertion direction of the tube to control tightening of the flanges, wherein the tube coupling body comprises a tube control collet support guiding movement of the tube control collet, and the tube control collet support includes at least one or more tube guide projections disposed between the respective resilient arms of the tube control collet.

2. The tube coupling according to claim 1, wherein the tube guide projection of the tube control collet support is formed inside one selected from a plurality of extending arms extended from a cylindrical portion, and the tube control collet is inserted into the cylindrical portion of the tube control collet support to move the flanges of the tube control collet in slots between the respective extending arms.

3. The tube coupling according to claim 2, wherein the tube guide projections are provided in the respective extending arms one to one.

4. The tube coupling according to claim 2, wherein the flanges of the resilient arms are respectively locked in edges formed at the boundary between the cylindrical portion and the slots to control tightening of the tube, and the flanges abutting the edges are provided with tapered portions formed toward the extraction direction of the tube .

5. The tube coupling according to claim 4, wherein the tapered portions of the flanges are additionally provided with a flange at the rear end.

6. The tube coupling according to claim 1 or 2, wherein the tube control collet support is provided with locking projections on the outer surface, and the locking projections are inserted into slots formed in the tube coupling body.

7. The tube coupling according to claim 1 or 2, wherein the flanges of the resilient arms are provided with teeth on the lower surface, and the ends of the teeth are projected much more than the ends of the tube guide projections in a state that the tube is not inserted into the coupling body.

8. The tube coupling according to claim 1 or 2, wherein the tube guide projections are linearly formed along the insertion direction of the tube.

9. The tube coupling according to claim 1 or 2, wherein the resilient arms of the tube control collet are formed to correspond to the extending arms of the tube control collet support one to one.

10. The tube coupling according to claim 1 or 2, wherein O-ring is inserted between an inner end of the tube control collet support and an inner edge formed in a through hole in the tube coupling body.

11. A tube coupling comprising a tube control collet inserted into a coupling body of a tube, the tube control collet including a plurality of resilient arms extended from one end of a cylindrical portion and flanges provided at the outer side of each resilient arm, movement in an extraction direction of the tube inserted into the tube coupling body being stopped by tightening of the flanges and the resilient arms being pushed to an insertion direction of the tube to control tightening of the flanges, wherein the tube coupling body comprises a tube control collet support guiding movement of the tube control collet, and the tube control collet support includes a cylindrical portion, a plurality of extending arms extended from the cylindrical portion, and slots formed between the respective extending arms, guiding the flanges of the resilient arms.

12. The tube coupling according to claim 11, wherein the resilient arms include tube guide projections on the lower surface.

13. The tube coupling according to claim 11 or 12, wherein the flanges of the resilient arms are respectively locked in edges formed at the boundary between the cylindrical portion and the slots to control tightening of the tube, and the flanges abutting the edges are provided with tapered portions formed toward the extraction direction of the tube.

14. A tube coupling comprising a tube control collet inserted into a coupling body of a tube, the tube control collet including a plurality of resilient arms extended from one end of a cylindrical portion and flanges provided at the outer side of each resilient arm, movement in an extraction direction of the tube inserted into the coupling body being stopped by tightening of the flanges and the resilient arms being pushed to the insertion direction of the tube to control tightening of the flanges, wherein the coupling body comprises a tube control collet support guiding movement of the tube control collet, the tube control collet support being fixed to a tight cap coupled with the coupling body, and the flanges of the tube control collet inserted into the tube control collet support are tightened along a tapered portion formed in the coupling body.

15. The tube coupling according to claim 14, wherein the tube control collet support includes at least one or more tube guide projections disposed between the resilient arms of the tube control collet.

16. The tube coupling according to claim 15, wherein the tube guide projections of the tube control collet support are formed inside one selected from a plurality of extending arms extended from a cylindrical portion, and the tube control collet is inserted into the cylindrical portion of the tube control collet support to move the resilient arms of the tube control collet in slots formed between the respective extending arms.

17. The tube coupling according to claim 16, wherein edges are formed at the boundary between the cylindrical portion and the slots of the tube control collet support, and tapered portions are formed in the flanges of the resilient arms of the tube control collet and abut the edges of the tube control collet support when the flanges are tightened along the tapered portion formed in the coupling body.

18. The tube coupling according to claim 17, wherein the tapered portions of the flanges of the tube control collet are formed toward the extraction direction of the tube .

19. The tube coupling according to any one of claim 14 to 10, wherein the tight cap includes an annular projection on the inner surface, and the annular projection is inserted into a clamp for the tight cap, which is formed on the outer surface of the cylindrical portion of the tube control collet support.

20. The tube coupling according to claim 19, wherein the tube control collet support is provided with locking projections on the outer surface, and the locking projections are inserted into slots formed in the .tube coupling body to flexibly move therein.