WO1999004189A2

WO1999004189A2 - Tube coupling

Info

Publication number: WO1999004189A2
Application number: PCT/US1998/014784
Authority: WO
Inventors: Carl H. Furman
Original assignee: Furman Carl H
Priority date: 1997-07-17
Filing date: 1998-07-16
Publication date: 1999-01-28
Also published as: AU8572998A

Abstract

The invention is coupling for tubes such as pipes or conduits suitable for liquids, gases, or electrical or optical cables and the like. Preferred embodiments of the coupling comprise a coupling body (11) comprising a well (12) adapted to receive and to optionally engage an end of a tube (20), a retaining ring (14) adapted to fit inside the well and to engage the outer surface (22) of the tube, and a stop (15) adapted to engage the retaining ring such that when the tube is extracted slightly from the coupling body, or when pressure is introduced within the well, as by fluid pressure, the retaining ring is displaced into contact against the stop in such fashion that portions of the ring not engaged by the stop are further displaced than those which are. Non-uniform displacement of the retaining ring about the tube results in engagement and binding between the inner edges of the ring and the outer surface, such that extraction of the tube from the coupling is prevented.

Description

Title: TUBE COUPLING

This application claims the benefit of United States Provisional Applications Serial No. 60/052,828, entitled Tube Coupling, filed July 17, 1997; and Serial No. 60/069,544, also entitled Tube Coupling, filed December 12, 1997.

TECHNICAL FIELD The invention relates to coupling for tubes, pipes, and conduits; more particularly, it relates to method and apparatus for mechanical, fluid-tight coupling of tubes, pipes, conduits and the like.

BACKGROUND OF THE INVENTION The problem of achieving effective fluid-tight connection between sections of tubing, pipes, and conduits has long vexed humankind. Even today the problem of establishing such connections in a simple, durable, damage tolerant, economical, easy-to-accomplish-and- maintain, sure manner remains.

Compression fittings are among the many less than fully satisfactory solutions that have been offered. Most compression fittings used, for example, in the plumbing industry employ single sealing members compressed during installation around a tube or pipe by the tightening of a threaded nut over the sealing area. Actual coupling of the tube or pipe to the fitting, however, is generally accomplished only at the expense of permanent deformation of the tube or pipe, the deformation being of such a nature as to render the tube or pipe incapable of removal and/or functional reuse in second- or third-generation applications, or even of simple resealing or repair. That is, once installed in a compression fitting, the pipe or tube is generally rendered useless for any other uses or reuses, or after any disturbance. Moreover, most compression fittings require the use of special installation techniques, which must be learned at considerable cost and which must be applied in precise manner — and which, if applied incorrectly or to configurations not suited to the particular technique, can result in permanent and costly damage. Moreover, most compression fitting installations require the use of a multiplicity of tools. For example, a minimum of two wrenches is generally required. In addition, most compression-fitting techniques require specific seals, made of specific materials, for each of the various tubing or piping materials.

It is another characteristic of most conventional coupling methods that a brittle or inflexible and substantially rigid joint results, so that if the joint is subjected to any flexure or bending loads, or even to substantial torques, any sealing in the coupling can be broken, with resultant leakage. Repeated loadings of relatively small magnitude may also frequently lead to leakage.

DISCLOSURE OF THE INVENTION Accordingly, it is an object of the invention to provide a simple, durable, damage tolerant, economical, easy-to-install and easy-to-maintain, sure coupling for tubes, pipes, and conduits.

It is a further object of the invention to provide such a coupling applicable to the plumbing, hydraulic, pneumatic, gas-handling, chemical, electrical, and optical fields. It is another object of the invention to provide such a coupling capable of use in high- pressure applications.

It is another object of the invention to provide such a coupling which does not require or entail the permanent deformation of or damage to the end of the tube, pipe, or conduit to which the coupling is applied. It another object of the invention to provide such a coupling which permits the re-use or reinstallation of a previously coupled tube, pipe, or conduit.

It another object of the invention to provide such a coupling which permits a coupled tube, pipe, or conduit to turn freely after installation.

It is a further object of the invention to provide such a coupling which is susceptible of simple installation techniques independent of the materials used in the tubes, pipes, or conduits to be coupled, and which may be completed with the use of minimum numbers of tools. It is yet another object of the invention to meet any or all of the needs summarized above.

These and such other objects of the invention as will become evident from the disclosure below are met by the invention disclosed herein.

The invention addresses these concerns and provides such a system. The invention provides a coupling for tubes such as pipes or conduits suitable for liquids, gases, or even electrical or optical cables and the like. Preferred embodiments of the coupling comprise a coupling body comprising a well adapted to receive and to optionally engage an end of a tube, at least one retaining ring adapted to fit inside the well and to engage the outer surface of the tube, and a stop adapted to engage the retaining ring such that when the tube is retracted slightly from the coupling body, or when pressure is introduced within the well, as by fluid pressure, the retaining ring is displaced into contact against the stop in such fashion that portions of the ring not engaged by the stop are further displaced than those which are, resulting in a non-uniform displacement or rotation of the retaining ring about the which tube results in engagement and binding between the inner edges of the ring and the outer surface of the tube, such that undesired extraction of the tube from the coupling is prevented. The coupling optionally comprises seals and caps in order to provide gas- or liquid-tight connections where desired. In fluid-tight or pressurized applications comprising seals, the retaining ring, being generally displaced by the sealing ring under pressure within the tube well, preferably performs the dual functions of retaining the seal in its proper position and, by its binding engagement with the tube or pipe, preventing removal or retraction of the tube or pipe from the coupling body. While many of the advantages of the invention are best realized in the plumbing field, the invention is also well suited for use, with or without seals, in the handling of gases and in electrical and optical systems. The invention is adaptable to use with any conventional plumbing, electrical, or conduit-related fittings, such as valves, filters, taps, or splices.

A basic embodiment of one aspect of the invention, and one particularly well suited to liquid or gas applications under pressure, such as plumbing or hydraulic systems, is a tube coupling which comprises a coupling body, the coupling body in turn comprising a tube well adapted to accept an end of a tube, pipe, or conduit to be coupled to another section of tubing, etc., or to a valve, gauge, pump, or other fitting or component; at least one retaining ring sized and adapted to engage the outer surface of the tube; and a stop adapted restrain the retaining ring relative to the coupling body and to cause the retaining ring to rotate into binding engagement with the tube, such that the tube is restrained relative to the coupling body and therefore relative to any component or device to which the coupling may be attached, when the tube is retracted from the well or when the tube or coupling body is charged with pressure.

In its most basic embodiment the invention comprises nothing more than a pair of tube ends, the first tube end and a second tube end, the first being large enough to fit over the outer surface of the second and to accommodate a retaining ring disposed about the outer surface of the second; and a stop adapted to restrain the retaining ring with respect to the first tube and to cause the retaining ring to rotate into binding engagement with the second tube when tubes are pulled apart or when the retaining ring is otherwise displaced, as by an internal pressure. In such embodiments the tube well comprises of the inner surface of the second tube. The coupling body may be used to form a portion of any fitting or component of a fluid, hydraulic, or electrical system, or the like, to which the coupling of a generally cylindrical tube, pipe, or conduit might be desired. For example, the coupling body may be attached to or an integral part of a pipe connector, a gauge, valve, instrument, or any other component of a tube, pipe, or conduit system. It may even take so simple a form as the end of a second portion of tube or pipe. The portion of the coupling body generally in engagement with the tube and the other components of the coupling is often generally cylindrically shaped, and is open at the end at which the tube, etc., is to be coupled to the body. The opening thus formed, which is referred to herein as the tube well, in the coupling body is generally adapted both to receive an end of the tube to be coupled and to accommodate, between the tube end and the inner surface of the coupling body, a retaining ring. In preferred embodiments for plumbing or hydraulic or other fluid applications or the like, the tube well, a seal interposed between the retaining ring and the end of the tube, and the retaining ring are sized relative to each other so as to effect, when the coupling is assembled, a fluid-tight seal. For example, in a plumbing application the tube is commonly a water pipe, with the seal being one or more O-rings or washers, with the pipe, the coupling body, and the O-ring or washer all sized to seal the joint and prevent water leakage when the coupling has been assembled. Thus the seal is typically sized or otherwise adapted to engage both the outer surface of the tube and the tube well, preferably at an inner surface of the tube well. It is to be understood, however, that couplings according to the invention may be used without seals in non-fluid tight connections, as for example in electrical wire conduits, with complete satisfaction. Thus embodiments of such couplings not comprising seals are considered to lie within the scope of the invention.

In fluid-tight embodiments of the invention comprising seals the retaining ring is generally disposed on the low-pressure side of the seal(s) and is sized and adapted to restrict excessive movement or deformation of the seal as the coupling is assembled or subjected to pressurization, so as to aid in maintaining the fluid-tightness of the seal. In some generally preferred embodiments the retaining ring includes a beveled surface on a side of the ring next to or proximate the seal or, where no seal is present, the end of the tube accepted or engaged by the tube well. As described more fully below, and as may be seen in the Figures, beveling the retaining ring allows the ring to rotate to a slightly greater extent than might otherwise be possible about the tube and enhances the grip of the retaining ring upon the tube, and therefore the retaining effect of the retaining ring. Generally preferred embodiments of the retaining ring sometimes also include a chamfer on an inner diameter of the ring at a side of the ring distal to or opposite the seal, where a seal is present, or distal to the end of the tube accepted by the tube well where a seal is not present. The chamfer guides the insertion of the tube, centers the tube on entry to the o-ring, further enhances the retaining performance of the retaining ring, and can act to improve the durability of the coupling, especially in applications involving plastic tubes, pipes, etc, by for example reducing stress concentrations on the surface of the tube. In applications involving the use of plastic (e.g., PVC) tubes, with relatively low internal pressure when charged, the chamfer is especially beneficial, in that it improves the grip of the ring upon the tube. It has been found to be particularly advantageous in many applications, and in particular those applications employing relatively "soft" tubes such as PVC piping, to employ a plurality of retaining rings. In preferred embodiments of the invention employing more than one retaining ring the rings are disposed adjacent to each other on the outer surface of the tube, such that they may rotate and work together in engaging and restraining the tube. The presence of multiple retaining rings and their independent engagement of the tube results in an increased retaining capability for the tube, resulting in a stronger coupling, due to the presence of an increased number of binding surfaces or edges on the retaining rings. The number of retaining rings to be employed in specific applications varies, but the determination of a correct number for any particular application is a matter well within the skill of the ordinary coupling designer, once armed with the disclosure of the invention. In residential applications up to four retaining rings may be employed with great success. Seals suitable for use with the invention take many forms, many of which are already well known in the relevant fields. Generally, any seal useful or suitably adapted for the particular application to which a specific embodiment of the invention is to be put will serve. For example, for fluid-tight applications O-rings are well known and have been found to be particularly advantageous, as they provide excellent contact between the outer surface of the tube and the tube well, even when displaced or distended. A preferred seal for use in many applications of the invention, however, is a seal having at least one canted face. The canted face of such a seal may be used to induce an initial rotation in the retaining ring and provide a particularly quick, sure engagement between the retaining ring and the tube, or to assist in the initiation of such a rotation. A further preferred embodiment of a seal for the invention, and one which preferably comprises a canted face, is an annular seal which may preferably be provided with a notch or cut-out at some potion of its canted face (preferably at the extremity) to allow flexure in the seal when the seal is deformed downward by rotation of the retaining ring, or when the seal is engaged due to rotation of the retaining ring, and thereby to facilitate rotation of the retaining ring when the tube is inserted, without inducing undue or unwanted stress, or unwanted movement, in the seal during insertion of the tube. In any case, the selection of an appropriate seal will be well within the skill of the ordinary coupling designer armed with this disclosure.

It has been found that in some applications, and particularly hydraulic or other relatively high-pressure fluid applications, the performance of the seal may be improved by the use of a seal retainer to prevent excessive or unwanted displacement of the seal. Thus in many preferred embodiments of the invention in which a seal is present a seal retainer is incorporated. Generally the seal retainer is disposed between the seal and the retaining ring, and acts, with or without the retaining ring, to further reduce deformation or dislocation of the seal under pressure. The seal retainer may also itself act as a seal to augment the effect of the primary seal in ensuring the fluid-tight integrity of the system. In such applications the seal retainer serves to support the primary seal, generally in conjunction with the retaining ring, as the seal tends to displace or deform under pressure. In many embodiments the seal retainer function is filled by the employment of one or more O-rings in addition to the primary seal. The use of additional O-rings further enhances the sealing ability of the coupling, as each properly-sized additional O-ring may function as a seal in its own right. Many embodiments of the invention, and particularly those employed in pressurized fluid applications, further comprise a cap adapted to engage the end of the coupling body about the tube well. An inner surface of the cap is generally adapted to engage an outer surface of the coupling body, while an end of the cap comprises a hole of sufficient diameter to receive the end of the tube. In many embodiments, the cap-end hole receives the tube end closely enough to provide support to the tube during flexure, bending, or other loading of the coupling, thus strengthening the coupling and increasing its durability, potential operating pressure, and service life. Caps according to this aspect of the invention may be fastened, either removably or permanently, to the coupling body in many ways, including by means of the stop itself as by a screw driven through the cap and the coupling body; by the provision of threads on the inner surface of the cap and mating threads on the outer surface of the coupling body; or by the provision (particularly in plastic embodiments) of snap-fit arrangements. Caps may also be advantageously formed of washers peened into the top of the fitting body, with the retaining pin cut and bent as the washer is stamped.

The retaining ring stop of the invention may take a number of forms. Preferred stops may either comprise separate parts or may be made as integral portions of the retaining ring. The function of the retaining stop is to restrain the retaining ring relative to the coupling body and to cause the retaining ring to rotate into binding engagement with the tube when the tube is retracted slightly from the tube well or when the retaining ring is otherwise displaced, as by displacement under pressure of a seal, where present, and thereby to hold the tube in place, or restrain the tube relative to the coupling body. And any structure or combination of structures which will accomplish such a purpose will serve as a stop. In embodiments of the invention comprising stops integral to or otherwise attached to the retaining ring, the stop typically engages a recess, hole, or (other) stop surface in the interior of the tube well, or in the cap, such that when the tube is retracted or displaced or when the seal is displaced and contacts the retaining ring the retaining ring is forced into rotation and binding engagement about the tube. In such embodiments the stop may take the form of a tab or projection extending radially from the outer circumference of the retaining ring, or of a screw, pin, or other detent or equivalent structure so extending, or any other structure which will accomplish the stated purpose. In embodiments in which the stop is not attached to the retaining ring, it typically projects through the tube well wall and into the tube well far enough to engage a portion (a "stop surface") of the retaining ring sufficiently to prevent the retaining ring from departing the tube well when the retaining ring is displaced by movement of the seal (as under pressure) or when the tube is pulled outward away from the coupling body. Again, the stop in such embodiments acts, when displaced by movement of the seal or tube, or when rotated about the tube end, to bind the tube and thereby restrain it relative to the coupling body in the manner described. Many preferred embodiments of the invention employ as stops screws, pins, or other detents or structures driven through the tube well portion or end of the coupling body far enough protrude into the tube well and engage the retaining ring. Ordinary machine screws, set screws, or the like may be employed satisfactorily in the stop function. Optionally, screw embodiments of the stop may incorporate conical tips, which, when brought or driven into contact with the retaining ring, have been found to initiate or enhance rotation of the retaining ring with respect to the tube, and thus to improve retention performance of the retaining ring. Screw embodiments may also incorporate otherwise unthreaded tips, to prevent damage to the screw tip and appurtenant difficulty in removing or installing screws. It has also been found to be advantageous in many applications to employ screw stops incorporating conventional anti- theft heads (those facilitating installation of the screw, but so designed as to prevent removal, as by means of uni-directional mating designs engagement with screwdriver heads).

Alternatively, it has been found to be advantageous in many embodiments of the invention to utilize a clip-type retainer for the stop. Retainer clips useful herein include C- locks, or C-shaped clips having at their extremities pins long enough at one end to engage a hole passing partially through the coupling body, and at the other to engage a hole passing completely through the coupling body into the tube well and engage the stop surface of the retaining ring.

In some embodiments of the invention, particularly in those intended for use with relatively soft or thin-walled tubes, it is preferred to provide the coupling with an insert adapted to fit in or engage the inside of the tube, preferably near the tube end, to support the tube under transverse or otherwise radially-distending forces. Such inserts may take the form of annular rings (as for example a section of tubing or hollowed cylinder) and need be no longer than required to cover the region impacted by application of the transverse or radially- distending force. Preferred inserts comprise flanged ends adapted to engage a proximate end of the tube in which they are inserted, in order to help the insert retain a desired positioning inside the tube. The provision of such inserts may be especially advantageous in that the can improve contact, and therefore binding engagement, between retaimng rings and the tube surface, and thereby provide a very strong coupling.

A particular advantage offered by the invention is that it enables the disassembly of a coupling and the reassembly or reuse of some or all of its components; it is an object of the invention to make the disassembly process as simple as possible. Thus preferred embodiments of the invention are easily disassembled. One method of easing the disassembly process is to provide the cap with an access port for the insertion of a ring release tool. Such ports are generally provided at a location on the cap substantially opposite the stop, so that the tool may be inserted and used to push back the retaining ring in the manner described above, to release the purchase of the retaining ring and facilitate disengagement of the tube. Relatively small tools having straight or pointed tips are well suited to use as ring release tools in many embodiments of the invention. For example, an awl may easily be used to advantage as a release tool for many embodiments; for such a tool the port might take the shape of a hole or groove in the cap somewhat larger than the tip or point of the tool. As may be seen, however, any means of reversing the rotation of the retaining ring to the extent that it disengages the tube will permit disassembly of the connection. For example, it is often possible to cause the tube to be inserted slightly further into the coupling, until the retaining ring rotates back to its unengaged orientation and at least partially disengages the tube, and then twisting or turning the tube while pulling it out of the coupling.

Preferred embodiments of the coupling housing, retaining ring, cap, and stop are made from brass, steel (stainless, galvanized, or otherwise), or other metals, or plastic or any other materials from which pipes, conduits, and associated components are made. Seals according to the invention are made of any suitable sealing material, including plastic, rubber, or other conventional seal/washer/gasket materials. Preferred retaining rings according to the invention are made of metal or any other suitable material. In embodiments of the invention comprising retaining rings having integral stops, it is frequently convenient to stamp the rings out of sheet or plate stock in such fashion as to leave a projection or tab to act as the stop. But such rings may also be conveniently machined, molded, or otherwise formed, in a variety of manners, or assembled from several pieces. It is to be understood that any materials having sufficient strength, durability, damage tolerance, and fatigue- and corrosion- resistant characteristics to serve the functions described herein for the relevant components may be used and that any process suitable for the formation of serviceable parts will serve.. The selection of appropriate materials and manufacturing processes for a given application will be well within the ability of one having ordinary skill in the art of coupling design, once armed with the disclosure of the invention.

The invention is well suited for use in coupling tubes, pipes, conduits, and the like made of any materials, including copper, lead, steel, PVC, CPVC, polybutelene, Wirsbo Pex, Polyethelyne, Galvanized steel, brass, and many others.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic view of a dissembled preferred embodiment of the invention.

Figure 2a is a cutaway schematic view of an assembled preferred embodiment of the invention, showing the retaining ring in an unset position. Figure 2b is a cutaway schematic view of an assembled alternative preferred embodiment of the invention showing the retaining ring in an unset position.

Figure 3 is a cutaway schematic view of an assembled preferred embodiment of the invention, showing the retaining ring in a set position.

Figure 4 is a cutaway schematic view of an embodiment of the cap and coupling body of the invention.

Figure 5 is a cutaway schematic and sectional view of a portion of a preferred embodiment of the invention, showing particularly a clip embodiment of the retaining ring stop.

Figure 6 is a sectional view of various embodiments of the retaining ring of the invention.

Figure 7 is an isometric view of a preferred embodiment of the cap aspect of the invention, showing an embodiment of the ring release access aspect of the invention.

Figure 8 is a schematic view of a preferred embodiment of the invention comprising a retaining ring incorporating an integral stop. Figure 9 is a cutaway sectional view of a preferred embodiment of the invention comprising an annular seal and a plurality of retaining rings.

Figure 10 is a schematic view of an annular seal according to the invention. Figure 11 is a top plan view of an alternative preferred embodiment of a tube coupling according to the invention.

Figure 12 is a side schematic view of the alternative preferred embodiment depicted in Figure 11. Figure 13 is a top plan view of a preferred embodiment of a retaining ring according to the invention.

Figure 14 is a sectional schematic view of an alternative embodiment of a tube coupling according to the invention.

Figure 15 is a perspective view of a preferred embodiment of a stop ring according to the invention.

BEST MODE OF CARRYING OUT THE INVENTION The terms tube, pipe, and conduit, and any similar terms, are used interchangeably in this specification to denote substantially tubular structures, and may include tubes, pipes, and conduits of any sort, including wires, hoses, and shafts, solid or hollow.

Turning now to the drawings, the invention will be described in a preferred embodiment by reference to the numerals of the drawing figures wherein like numbers indicate like parts.

Figure 1 is a schematic view of a dissembled preferred embodiment of the invention. Tube coupling 10 comprises coupling body 11 compresses inner surface 131, tube well 12, , which is shown only in part; the coupling body may be attached to or an integral part of a connector, a gauge, and instrument, a valve, or any other component of a tube or pipe system. The coupling body comprises tube well 12. On assembly of the coupling, optional seal 13 (shown as an O-ring; any type of seal or seal material will serve, including paste or liquid seals) and seal retainer 19 (also shown as an O-ring) are placed in the tube well, with retaining ring 14 inserted behind. Optional cap 30 is then installed over outer surface 41 of the coupling body. Inner surface 32 of the cap is shown with optional threads, which if present mate with threads on the outer surface of the coupling body, so that the cap would be "screwed onto" the coupling body. Once the cap has been installed, stop 15 (depicted as a screw) is installed in hole 40 in the coupling body through hole 31 in the cap. In preferred installations, the stop is initially installed only to the point at which it makes a relatively slight initial contact with stop surface 16 on the retaining ring and initiates rotational displacement of the retaining ring. (Slight initial rotation of the retaining ring helps ensure immediate locking of tube 20 on insertion of the tube into the tube well through the retaining ring by any slight retraction of the tube, but is not necessary; in most applications no initial rotation of the retaining ring is required. Where sure instant grip is desirable, however, the technique is particularly advantageous.) Tube 20 is then inserted through hole 35 of the cap into tube well 20, passing through retaining ring 14, seal retainer 19, and seal 13 as it enters, with outer surface 22 of the tube generally making sealing contact seal 13 and seal retainer 19. Optionally end 21 of the tube engages the inner extremities of tube well 12, including inner tube well surface 63. The slight initial rotation of the retaining ring referred to above may be readily accomplished by placement of the sealing ring or seal retainer such that the restrained portion of the retaining ring is prevented from entering the tube well to as great an extent as the unrestrained portion, so that the ring is rotated with respect to the tube it is to retain — but not to such an extent (which, as will be appreciated by those skilled in the art, is dependent upon the relative sizes of the tube and the retaining ring, and the clearance between them) that the tube is prevented from insertion into the sealing ring(s) or the tube well. Such an initial rotation may be provided by suitable employment of the stop, as described, or, as described below, by suitable shaping or placement of the seal, where one is present.

Figure 2a is a cutaway schematic view of an assembled preferred embodiment of tube coupling 10. Tube 20 is in place, with tube end 21 in or near contact with inner surface 63 of tube well 12 and in contact with seal 13, seal retainer 19, and with retaining ring 14 in place. Seal 13 and seal retainer 19 are shown in sealing engagement with outer surface 22 of the tube and with the tube well. Stop 15 is not fully seated, with tapered, unthreaded tip 51 not yet in contact retaining ring 14, which is in an unset position, contacting but not yet rotationally displaced on or binding tube 20, and perpendicular to longitudinal axis 99 of the tube.

Figure 2b is a cutaway schematic view of an assembled alternative preferred embodiment of the invention showing the retaining ring in an unset position. In the alternative embodiment shown tube well 12 has been provided with inner recess 73, which is sized to receive tube end 21 closely enough to provide tube 20 and the overall coupling with some additional support. Inner recess 73 serves to hold tube end 21 from shifting out of line with coupling 10 or with any other tube or structure attached to the coupling, by resisting translation, rotation, and bending of the tube within the coupling, and to stop tube 20 from insertion too deep within the coupling. It is noted that these same functions may be accomplished, in embodiments of the invention comprising seals or sealing rings, by suitable sizing and adaptation of the seals, including the annular or canted-face seals described herein. In addition, the function of stopping the tube from insertion too deep within the tube may be accomplished by use of a stop within the coupling body, either be means of a pin or other structure protruding through the coupling wall or by means of an insert adapted to hold within the coupling.

Figure 3 continues the cutaway schematic view of the assembled preferred embodiment of tube coupling 10 depicted in Figure 2a. Stop 15 has been fully seated, and tube 20 has been retracted slightly from the tube well, in the direction of arrow 98, such that tube end 21 is shown no longer in contact with inner surface 63 of the tube well. Seal 13 and seal retainer 19 have been displaced by the relative movement of the tube, but retain their sealing engagement on the tube and the tube well. Retaining ring 14 has been displaced into full contact with stop 15, with the result that portions of the ring not in contact with the stop have experienced greater relative displacement than those which are, and the retaining ring has rotated through angle 97 with respect to its former perpendicular position with respect to longitudinal tube axis 99. Note that the rotation of the retaining ring may be accomplished either through contact with stop 15 or by retraction of tube 20 from the tube well, or by a combination of the two. For purposes of the invention, the particular mechanism employed to initiate and complete binding engagement of the retaining ring on the tube is immaterial. In the Figure, rotation of retaining ring 14 has brought edges 61 and 62 of the ring into binding contact or engagement with outer surface 22 of the tube, thus restraining tube 20 within the coupling. Displacement of retaining ring 14 into binding engagement with the tube may be accomplished either through relative displacement of the tube, as through a partial withdrawal or retraction of the tube, as described, or by charging the system such that pressure inside the well displaces the seal and, if one is present, the seal retainer such that the seal and / or seal retainer displace the retaining ring into contact with the stop and binding engagement with the tube.

The gripping and sealing powers of the coupling are functions of, among other factors, the relative dimensions of the various parts of the coupling assembly, including particularly the tube, the seal, the seal retainer, the retaining ring, and the tube well. Clearances or interferences often thousandths, thousandths, hundredths, or even tenths of an inch may be expected to give satisfactory results, depending upon the relative size of the coupling and the operating pressure, if any, the coupling is expected to withstand. While for most plumbing applications involving tube sizes of 1/2 inch to 2 inches clearances and interferences of 1 to 10 thousandths is desirable and has given very satisfactory results, the selection of relative component dimensions, including particularly clearances and interferences between the various components, will be well within the skill of the ordinary coupling designer armed with the disclosure of the invention. Couplings for pipes having 1/8" to 3/4" diameter have been tested and found to operate very satisfactorily, with such tolerances, at pressures up to approximately 600 psi.

One of the functions of the coupling cap is to stabilize and support the tube in lateral and bending loads following installation. In the Figures hole surface 35 in cap 30 is shown in close contact with outer surface 22 of the tube. As will be apparent to one having ordinary skill in the art of coupling design and installation, closer contact between hole surface 35 and the tube generally provides greater and more immediate support to the tube, whereas greater clearance between the tube and the cap generally allows a more flexible coupling. Selection of appropriate clearances between the cap and the tube will be well within the skill of the ordinary coupling designer, once armed with the disclosure of the invention. Figure 4 is a cutaway schematic view of an alternative embodiment of the cap - coupling body connection of the invention. Cap 30 comprises groove 33, which upon installation of the cap on coupling body of 11 will work in snapping cooperation with snap ring 42 on the coupling body. Such snap-fit arrangements are in general most advantageously employed with plastic and relatively thin-gage metal embodiments of the coupling.

Figure 5 is a cutaway schematic view of an alternative embodiment of the cap - coupling body connection of the invention, showing a clip embodiment of the retaining ring stop adapted to simultaneously act as a stop for the retaining ring and to secure the cap upon the coupling body. C-clip 52 snaps into place around the outer surface of the cap, with long end 53 of the clip penetrating both cap 30 and coupling body 11 through holes 31 and 40, so that the long end of the clip protrudes into tube well 12 and may contact stop surface 16 of retaining ring 14, thus acting as a stop for the retaining ring. At the same time, short end 54 of the clip penetrates the cap through hole 55 and partially into coupling body 11, in hole 56, but does not penetrate into tube well 12. Thus cap 30 is supported at two points on couphng body 11, but retaining ring 14 is stopped only on the stop side.

Figure 6 is a sectional view of various embodiments of the retaining ring of the invention. Figure 6a depicts a flat cylindrical ring having no bevel and no chamfer. Introduction of bevel 17, as shown in Figure 6b, is found to improve performance of the coupling in many applications, particularly in connection with the use of plastic or PVC tubing or pipe and equivalents. Introduction of chamfer 18, as shown in Figure 6c (either with or without bevel 17) has been found to improve binding with some metal tubes, particularly copper. Various combinations of bevels and chamfers have been found to provide various advantages in various applications as well. Generally bevels and chamfers of 10 - 70 degrees, as measured through angle 96 of Figure 6b for bevels and angle 95 of Figure 6c for chamfers, have given best results. The selection of particular values of bevel angle 96 and chamfer angle 95 will depend upon overall dimensions of the coupling, materials used, and anticipated system pressures; selection of appropriate particular angles will be well within the skill of the ordinary coupling designer, once armed with the disclosure of the invention.

Figure 7 is an isometric view of a preferred embodiment of the cap aspect of the invention, showing an embodiment of the ring release access aspect of the invention. Access port 34 has been opened in end 36 of cap 30, substantially opposite stop hole 31, to allow insertion of a ring release tool through the port. In such embodiments the tip of a release tool is inserted through port 34 to contact a portion of the retaining ring generally opposite the stop and to return the ring toward perpendicular alignment with respect to the tube longitudinal axis, thus releasing the engagement of the ring on the outer surface of the tube and permitting the tube and coupling body to be decoupled.

Figure 8 is a schematic view of a preferred embodiment of the invention comprising a retaining ring incorporating an integral stop. The coupling of the invention is shown in Figure 8 in one of its most basic forms: coupling body 11 is a plain substantially cylindrical tube of sufficient diameter to fit over or accommodate the outer circumference of retaining ring 14 (excepting stop projection 15) and outer surface 22 of tube end 20. Thus coupling body 11 might be the end of a second tube, or any other similar body; tube well 12 consists of no more in this case than the inner surface of the tube. Retaining ring 14 comprises integral stop 15, which is shown in the form of a projecting tab or extension adapted to fit inside stop hole 67 in coupling body 11 and to engage stop surface 16. To assemble such an embodiment of the invention ring 14 is place inside tube well 12 in a somewhat rotated orientation, such that stop 15 enters stop hole 67 and such that the retaining ring may be rotated to a substantially upright position (that is, so that it is substantially normal to tube 20 and in a position to fit without binding around its end). Tube end 20 is then inserted into tube well 12 through ring 14 and retracted, so that tube 14, pulled by frictional forces or other available displacing forces, rotates slightly as stop 15 engages stop surface 16, and rotates into binding engagement on the tube, thus holding the tube in place and completing the coupling.

Figure 9 is a cutaway sectional view of a preferred embodiment of the invention comprising an annular seal and a plurality of retaining rings. The general configuration of this embodiment of the invention is similar to that shown in Figures 1 - 3, but there are now shown a plurality of retaining rings 14. Leftmost ring 14 comprises integral stop 15, which protrudes through stop hole 67 in couphng body 11 to engages stop surface 16. Rings 14 have each been rotated into binding engagement with tube 20. Annular seal 64 is in place around tube end 20 and is in sealing engagement with outer surface 22 of the tube and with tube well 12 (shown as the mere interior of coupling body 11, which may be a simple tube). Seal cup 68, an annular groove formed in the end of annular seal 64, improves sealing contact between the seal, tube 20, and coupling body 11 by expanding when pressure is applied inside the tubes. Seal 64 further comprises canted face 66, which among other functions serves to provide initial rotation to rings 14 on assembly of the coupling. Also shown in the Figure is insert 70, which is sized to engage the inner surface of tube 20 and to provide support to the tube from radial forces applied to the tube by rings 14 and other sources. Insert 70 comprises flange 74 to help locate and retain insert 70 in position near end 21 of the tube. Note that any one or several, or all, of rings 14 may comprise stops 15. Moreover, end 75 of the coupling body may crimped or otherwise bent or formed in order to fulfill the function of a couphng cap in retaining rings 14, any seals, and any seal retainers within the coupling body prior to installation of the tube and to help retain any or all of them in proper position afterward. Coupling body 11, as depicted in the Figure, further comprises optional crimp or annular indentation 76, which may be formed, molded, or provided through any other suitable process and which serves to prevent seal 13 from moving out of place during assembly of the coupling. In preferred embodiments of the invention the seal itself is sized suitably to grip the outer surface of the tube and/or the inner surface of the coupling body with sufficient force to prevent any undesired displacement of the seal.

Figure 10 is a schematic view of an annular seal according to the invention. Annular seal 64 comprises canted face 66 and notch 65, which provides a certain and controllable amount of flexure in the face of the seal and thereby facilitates installation of the seal inside the tube well of a coupling and insertion of a tube through inner surface 71 of the seal.

An alternative embodiment of the stop function and the retaining ring of the tube coupling according to the invention is shown in Figures 11 - 13. Coupling body 11 comprises tube well 12, tube stop surface 63, and optional retention chamber 132. Deformable seal 13 is in place to receive a tube in sealing engagement. Coupling body 11 fUrther comprises recess 133, which has been placed in the side of retention chamber 132 (or optionally in tube well 12) to receive stop 15 of retention ring 15. To establish a tube coupling retaining ring 14 is placed in coupling housing 11, stop 15 first. Stop 15 is inserted in recess 133, and tab 134 is pushed into slot 135. A tube end is then inserted into the coupling housing through the opening in retaining ring 14 and through seal 13 in the manner described above for other embodiments. The tube is then retracted slightly from the coupling so as to set the retaining ring. If and when it is desired to remove the tube from the coupling, tab 134 is pushed back toward the open end of the coupling body to release the tube, and the tube is withdrawn. In cases in which the coupling is to be transported as an assembled unit, the seal and the retaining ring are inserted, with the retaining ring (and therefore the seal) being retained by slight bending of the coupling body at the ends of slot 135, or by providing tab 134 and slot 135 with an appropriate interference fit. Alternatively, a plastic or other elastic or malleable plug may be inserted in slot 135 behind tab 134. An alternative embodiment of the coupling according to the invention provided as an integral part of a fitting, such as a pump housing or other plumbing device, is shown in Figures 14 and 15. Coupling 10 comprises coupling body 11, which is an integral part of a larger fitting, which includes tube well 12 and optional retention chamber 132. The arrangement of deformable seal 13 and retaining ring 14 is as described. In addition, stop ring 141 has been placed atop retaining ring 14, with integral stop 15 adjacent the retaining ring. When a tube is inserted into the coupling and slightly retracted, retaining ring 14 rotates as described above to engage the outer surface of the tube, the rotation of the retaining ring be aided or induced by contact of the ring with stop 15. Stop ring 141 may be retained within the coupling body by means of an interference fit, by employment of a peen installation process, or by appropriately restrictive forming or deformation of the opening of the coupling body. In the embodiment shown, stop ring 141 comprises groove 142 to accommodate a release tool for use in disengaging retaining ring 14 and releasing the tube in the manner described above.

It may be seen from the foregoing descriptions of the assembly and release of the coupling system that assembly and disassembly of the system may be accomplished very easily, with few or no tools. For example, embodiments of the coupling utilizing set screws may be assembled with nothing more than a screwdriver, whereas embodiments employing C-clip stops may be assembled with no tools at all. In addition, virtually any embodiment of the coupling may be released and disassembled with an awl, screwdriver, or similar tool, and reused to the satisfaction of the installer. Moreover, no specialized techniques are required for assembling or dismantling the system. With regard to systems and components above referred to, but not otherwise specified or described in detail herein, the workings and specifications of such systems and components and the manner in which they may be made or assembled or used, both cooperatively with each other and with the other elements of the invention described herein to effect the purposes herein disclosed, are all believed to be well within the knowledge of those skilled in the art. No concerted attempt to repeat here what is generally known to the artisan has therefore been made.

INDUSTRIAL APPLICABILITY

The invention has applicability to the tubing, piping, and conduit fields, particularly in the hydraulic, plumbing, electrical, pneumatic, and optical industries. The invention provides greatly improved, simple, durable, damage tolerant, economical, easy-to-install and easy-to-maintain, sure coupling for tubes, pipes, and conduits.

In compliance with the statute, the invention has been described in language more or less specific as to structural features. It is to be understood, however, that the invention is not limited to the specific features shown, since the means and construction shown comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims, appropriately interpreted in accordance with the doctrine of equivalents.

Claims

CLAIMSI claim:

1. A tube coupling, the coupling comprising: a coupling body having a tube well adapted to accept an end of a tube; at least one retaining ring adapted to engage an outer surface of the tube; and a stop adapted to restrain the retaining ring relative to the coupling body and to rotate the retaining ring into binding engagement with the tube, whereby the tube is restrained relative to the coupling body.

2. The coupling of Claim 1, comprising a plurality of retaining rings.

3. The coupling of Claim 1, wherein the retaining ring further comprises a beveled surface on a side of the ring proximate the end of the tube accepted by the tube well.

4. The coupling of Claim 1, wherein the retaining ring further comprises a chamfer on an inner diameter of the ring at a side of the ring distal to the end of the tube accepted by the tube well.

5. The coupling of Claim 1, further comprising a seal adapted to engage the outer surface of the tube and the tube well.

6. The coupling of Claim 5, further comprising a seal retainer, the seal retainer substantially interposed between the seal and the retaining ring.

7. The coupling of Claim 1, further comprising a cap adapted to engage an end of the coupling body, the cap comprising an inner surface and an end, the inner surface of the cap adapted to engage an outer surface of the couphng body and the cap end comprising a hole of sufficient diameter to receive the end of the tube.

8. The coupling of Claim 7, wherein the cap is fastened to the coupling body by means of the stop.

9. The coupling of Claim 7, wherein the inner surface of the cap and the outer surface of the coupling body comprise threads whereby the cap may be attached to the coupling body.

10. The coupling of Claim 7, wherein the cap may be snapped to the coupling body.

11. The coupling of Claim 7, wherein the cap comprises an access port substantially opposite the stop, for insertion of a ring release tool.

12. The coupling of Claim 1, wherein the stop is integral to the retaining ring.

13. The coupling of Claim 1 , wherein the stop comprises a screw.

14. The couphng of Claim 13, wherein the screw comprises a conical tip.

15. The coupling of Claim 13, wherein the screw is an anti-theft screw.

16. The coupling of Claim 1, wherein the stop comprises a retainer clip.

17. The coupling of Claim 5, wherein the seal comprises at least one O-ring.

18. The coupling of Claim 5, wherein the seal comprises at least one canted face.

19. The coupling of Claim 18, wherein the seal is annular.

20. The coupling of Claim 19, wherein an extremity on the canted face comprises a cut- out to allow flexure in the seal when the seal is engaged by the retaining ring.

21. The coupling of Claim 1 , further comprising an insert adapted for engagement of an inner surface of the tube end, and for support thereof when the tube end is subjected to a radially distending force.