CONNECTOR FOR TUBULAR MEMBERS

Background Art

In conduit systems utilizing a plurality of lengths of tubular pipes or conduits, connector means must be provided for joining together the various lengths of tubing. Although connectors which engage the exterior surface of the tubing are well known, for some applications it is highly desirable to utilize a connector which engages the interior surfaces of the lengths of tubing being joined together. Exterior connectors are bulky and have outside diameters larger than the tubes. Additionally, for some applications, it is desirable that the internal diameter of the passageway defined by the interconnected lengths of tubing and the connector internal surface be substantially uniform. The desirability of having an uniform diameter passageway for the joined lengths of tubing and connector is particularly strong for joined tubes forming part of a fluid supply system or a system where wires or fiber optic bundles are passed through. Prior art conduit systems utilizing the "interior surface engagement" type of connector for joining adjacent lengths of tubing result in a passageway constriction which restricts the flow of fluid.

Disclosure of the Invention

The present invention is directed to a connector for joining together two lengths of tubing by engagement of the interior wall surfaces of adjacent ends to be joined while maintaining a substantially uniform internal diameter passageway for the flow of fluid or the passing of fiber optic bundles through the connector. The present invention is also directed to the combination of a connector and tubing and to a method for forming such combination. The tubing, prior to its

engagement by the connector, has a substantially uniform intemal diameter throughout including at the ends to be joined by the connector. The tubing is formed of a material having some resiliency and capability of being expanded. For example, the tubing is desirably manufactured of a plastic material such as high density polyethylene. In contrast, the connector is manufactured of a more rigid material such as metal, stainless steel or brass, for example, or a plastic material having significantly more rigidity than the material from which the tubing is manufactured. The connector extends along an axis from a first end face to a second end face and has (1 ) an interior surface with a diameter substantially equal to the internal diameter of the tubular members and (2) truncated areas adjacent each of the opposing end faces. The truncated areas are cut at an acute angle relative to the axis. Each of the truncated areas has a cross-sectional configuration normal to the axis defining a partial circle and the central area between each of the truncated areas has an internal surface cross-sectional configuration defining a complete circle. The truncated area is cut such that the cut face or edge defines a plane disposed at an angle of 30-45° relative to the axis and, at the end face, is on the opposite side of the axis from the portion of the cut face or edge closest to the opposing end. External threads extend throughout a major portion of each of the truncated areas and into the central area. Preferably a slightly smaller outside diameter lead-in portion is provided between each threaded portion and the respective end face adjacent thereto. As a result of the foregoing design, the end face circumscribes an arc which is less than a semi-circle. Therefore, the length of a chord extending between the outside surface to outside surface at each end face is less than the inside diameter of the plastic tubing thereby permitting such end face and truncated area adjacent thereto to be readily inserted into the end of the plastic tubing

even though the outside diameter defined by the external threads is larger than the inside diameter of the tubing. As the threads grip the smooth internal surface of the tubing as it is rotated therein, the rigid connector causes the interior surface of the tubing contacted thereby to expand slightly as the threads are engaged therewith with the result that, upon complete engagement of the tubing lengths, the passageway defined thereby and by the connector will have substantially the same internal diameter.

Description of the Drawings

Fig. 1 is a perspective view of the connector of the present invention.

Fig. 2 is an enlarged fragmentary view showing a portion of the threads. Fig. 3 is an elevational view, in section, showing the connector of the present invention and a pair of plastic tubular members about to be joined to opposing ends of the connector.

Fig. 4 is a view similar to Fig. 3 showing the connector partially engaged to the ends of the tubular members. Fig. 5 is a view similar to Figs. 3 and 4 showing the fully joined combination of the connector and tubular members. Fig. 6 is an end view of the connector.

Fig. 7 is an enlarged sectional view taken through line 7-7 of Fig. 6.

Description of the Preferred Embodiments

Referring now to the drawings, there is shown a connector 10 and a pair of tubular members 12 and 13 which are components of an overall tubular system (not shown). The tubular system may, for example, be a system for controlling the flow of fluids or a system forming a portion

of a fiber optic duct insert. Various types of fiber optic duct inserts are disclosed in U.S. Patent Nos. 4,582,093 and 4,674,167, both of which are assigned to the assignee of the present application. Although such prior art multi-chambered conduit inserts or fiber optic inserts are shown with sections of tubing having non-circular cross-sections, the connector of the present invention is specifically designed for use with tubing having a circular internal cross-sectional configuration.

As shown, the tubular member 12 has an internal surface 14 and tubular member 13 has an internal member 15, each of which internal surfaces 14 and 15 has a circular cross-sectional configuration of predetermined diameter D. The connector of the present invention is particularly well suited for use with plastic tubing having an internal diameter on the order of one inch to three inches; however, it could be used with tubing having larger or smaller diameters. The tubular member 12, the connector 10 and the tubular member 13 are shown aligned along an axis A. The tubular member 12 has an end face 16 which lies in a plane substantially perpendicular to the axis A and the tubular member 13 has an end face 17 which also lies in a plane substantially perpendicular to the axis A. The connector 10 extends from a first end face 20 to a second end face 21 and has a passageway 22 extending from the first end face to the second end face 21. The passageway 22 is defined by an inwardly facing wall surface 23 which lies on a cylinder having a diameter equal to the diameter D of the internal surface 14 and internal surface 15 of the tubular members 12 and 13, respectively.

Externally, the connector 10 is provided with a central collar 25 having flats 26 on opposing sides to permit engagement by a wrench for rotating the connector. The collar 25 has a first shoulder 36 and a second shoulder 46. Between the first end face 20 and the collar 25 is a first set of external threads 28 which are cut in a direction to engage

the internal surface 14 and draw the tubular member 12 into engagement when the connector 10 is rotated in a clockwise direction as viewed from the first end face 20. The connector 10 is provided with a second set of threads 29 in the area between the collar 25 and the second end face 21. The threads 29 are cut at an opposing direction to that of the threads 28 so that the threads 29 will become engaged with the internal surface 15 and draw the tubular member 13 into engagement when the connector 10 is rotated in the clockwise direction as viewed from the first end face 20. As can be seen in the drawings, the opposing ends of the connector 10 adjacent each of the end faces 20 and 21 are truncated. Thus, the connector 10 is cut forming at one end a cut face or edge 30 extending from a point of intersection 31 with the threads 28 to two points of intersection 32 with the first end face 20. Similarly, the opposing end is cut to provide a cut face or edge 40 extending from a point of intersection 41 with the threads 29 to two points of intersection 42 with the second end face 21 . The edges 30 and 40 each defines a plane extending at an angle X relative to the axis A. The angle X of each of the cut faces or edges 30 and 40 with respect to the axis A is in the range of 30° to 45° and preferably in the range of 35° to 40°.

Under one embodiment, the threads were provided with 16 starts, 16 threads per inch with the result that one inch of threaded engagement of each tubular member internal surface is achieved with one revolution of the connector 10 therein. Additionally, as can be readily seen from the drawings, the threads 28 and 29 extend beyond the respective points of intersection 31 and 41 toward the collar 25 such that there are a number of turns of each of the threads 28 and 29 between the respective points of intersection 31 and 41 and the collar 25. Thus, the portions of the connector between each of the points of intersection 31 and 41 and the end of each of the threads 28 and 29 adjacent the collar

25 will have a substantially circular cross-sectional configuration while that portion of the connector 10 between each of the respective points of intersection 31 and 41 and the respective end faces 20 and 21 , although lying on a circular path, as may be seen in Fig. 6, define an arc less than a circle.

As can be seen in the drawings and as previously discussed, each of the cut faces or edges 30 and 40 extend to points of intersection 32 and 42 with each of the respective end faces 20 and 21 . Each of the points of intersection 32 and 42 with the respective end faces 20 and 21 lie on the opposite side of the axis A from the respective points of intersection 31 and 41 . As a result, each of the end faces 20 and 21 defines an arc which is less than a semi-circle (See Fig. 6). Therefore, the length L of a chord from the outer surface to outer surface of each of the cut faces or edges 30 and 40 at the respective end faces 20 and 21 is less than the internal diameter D of the connector 10 and of the tubular members 12 and 13. Adjacent each of the end faces 20 and 21 , there is provided first and second non-threaded lead-in portions 34 and 44 of slightly reduced diameter from that of the threads 28 and 29.

Additionally, a chord extending parallel to the chord L between the outer surfaces of that portion of the connector at the leading ends 28A or 29A of the threads 29 or 29 will also be less than the diameter D. Since the lengths of such chords are less than the diameter D of the tubular members 12 and 13, the portions of the connector 10 adjacent the end faces 20 and 21 including a short portion of the threads 28 and 29 adjacent points of intersection 32 and 42, respectively, can be inserted into the tubular members 12 and 13. Thus, it is possible for the portions of the connector 10 from each of the end faces 20 and 21 to and including a substantial portion of the threads 28 and 29 to be introduced into the open end of the tubular members 12 and 13 even though the outer diameter of the threads 28 and 29 between the points

of intersection 31 and 41 and the collar 25 are substantially larger than the internal diameter of the respective tubular members as defined by their respective internal surfaces 14 and 15. The rotation of the connector with the ends 28A and 29A of the threads 28 and 29 adjacent the respective end faces 20 and 21 gripping the internal surface 14 and 15 respectively, will cause its respective engaged plastic tubular member 12 or 13 to expand slightly as the threads 28 and 29 form corresponding threads in the intemal surfaces 14 and 15, respectively. (See Figs. 5 and 7). The collar 25 has a maximum outside diameter which preferably is slightly less than the outside diameter of the external diameters of the respective tubular members 13 at the respective end faces 16 and 17 following the radial expansion of such tubular members in the areas adjacent such end faces 12 and 13 upon affixing of the connector 10 thereto. The collar 25 is provided with spaced apart shoulders 36 and 46. Upon affixing of the connector 10 to the tubular members, each of the end faces 16 and 17 will abut the adjacent shoulder 36 or 46.

Optionally, the connector may be provided with a pair of circumferential sealing barbs 37 and 47, one each in the areas between the shoulders 36 and 46 and the respective threads 28 and 29 adjacent thereto. The barbs 37 and 47 extend outwardly from the cylindrical portions between the shoulders 36 and 46 and the respective adjacent threads 28 and 29. Each of the barbs 37 and 47 has a cam face 38 and 48 respectively on the side facing its respective threads 28 or 29 which extends outwardly at an angle tapering in a direction toward the collar 25 such that the respective tubular member end face 16 or 17 may slide thereover as the connector 10 is rotated to full engagement with the tubular members 12 and 13. The sealing barbs 37 and 47 are also provided with a locking face 39 and 49 on the side facing the respective shoulders 36 and 46, which locking faces may be disposed at

substantially a right angle to the axis A or even reversed in order to assist the threads 28 and 29 in retaining the connector engaged to the tubular members 12 and 13. More importantly, the sealing barbs 37 and 47 have an annular configuration and function to provide a seal between the tubular members and the connector 10. The sealing barbs 37 and 47 extend outwardly to a greater radial extent that the threads 28 and 29. Additionally, the connector may, if desired, be provided with one or more ports 50 extending through the collar 25 as shown in phantom in Fig. 5. The ports 50 may be threaded and provided with plugs or charge ports to permit the introduction of pressurized fluid into the connected tubular members 12 and 13 and connector 10. The use of a pressurized system is particularly desirable for fiber optic conduit systems in order to retard the entry of water into the system.

Although the connector is particularly well suited for joining opposing ends of two adjacent tubular members, it is within the contemplation of the present invention to provide a connector having a single set of threads. This would permit the utilization of a similar concept for providing a plug in one end of the tubular member or in connecting a tubular member to another type of member, for example, the wall of a tank or a coupling engaged to a length of metal conduit. Other modifications will become readily apparent to those skilled in the art. Accordingly, the scope of the present invention should be determined only by the scope of the claims appended hereto.