Fitting having low volume crevice

A fitting for a fluid conduit includes a coupling body having an inside surface for engaging an outside surface of a fluid conduit and a shoulder portion for limiting axial insertion of the fluid conduit into the coupling body. At least one seal is formed on the inside surface of the coupling body. The at least one seal includes a proximal seal adjacent the shoulder portion. A ring is annularly disposed on the coupling body urging the at least one seal into the fluid conduit to seal and mechanically connect the coupling body to the fluid conduit.

BACKGROUND

The present invention relates, in general, to fluid fittings and, more particularly, to an improved fitting having a low volume crevice. In one embodiment, the fitting includes a coupling body having an inside surface for engaging an outside surface of a fluid conduit and a shoulder portion for limiting axial insertion of the fluid conduit into the coupling body. The fitting further includes at least one seal formed on the inside surface of the coupling body. The at least one seal includes a proximal seal adjacent the shoulder portion. The fitting also includes a ring annularly disposed on the coupling body urging the at least one seal into the fluid conduit to seal and mechanically connect the coupling body to the fluid conduit. The improved fitting will be described with particular reference to this embodiment, but it is to be appreciated that the improved fitting is also amenable to other like applications.

Various types of fittings have been developed for joining tubes and pipes to other tubes and pipes, or to other fluid apparatus such as pumps, fluid motors, actuation cylinders, etc. For thin walled tubing or pipe, various types of fittings are used which compress against the outside diameter of the tube or pipe to create a seal. One particular type of such a fitting includes a swage ring which is forced over the fitting to compress it radially inwardly against the tube or pipe to create a seal. Generally, this type of fitting has one or more circumferential teeth or ridges on its inside diameter which, when compressed inwardly by a swage ring, engage the outside diameter of the tube or pipe to create one or more leak-tight mechanical connections or joints between the tube or pipe and the fitting. This engagement of the sealing teeth of the fitting with the tube or pipe causes the pipe to be deformed radially inwardly, with the coupling body of the fitting located externally about the tube or pipe.

Examples of such mechanically attached fittings are provided in U.S. Pat. Nos. 4,482,174; 5,110,163; 5,114,191; and 6,692,040. One example installation tool employable for attaching these types of fittings to a tube or pipe is described in U.S. Pat. No. 5,305,510. All the teachings and substance of these patents are hereby expressly incorporated by reference into the present application.

The fittings described above are suitable for a variety of applications. However, in some applications, these fittings allow residual amounts of whatever passes through the fitting to accumulate in the fitting and/or between the fitting and the tube or pipe to which the fitting is attached. More particularly, a fluid or other substance may undesirably accumulate between the end of the pipe and the fitting body, as well as between an outside surface of the pipe and the fitting, extending axially to the first seal. Reducing this amount of space between the pipe and the fitting could desirably lessen the area in which residual amounts may accumulate. Thus, any improvement to the fitting that would lessen the area in which residue may gather is deemed desirable.

SUMMARY

In accordance with one aspect, a new and improved fitting for a fluid conduit is provided. More particularly, in accordance with this aspect, the fitting includes a coupling body having an inside surface for engaging an outside surface of a fluid conduit and a shoulder portion for limiting axial insertion of the fluid conduit into the coupling body. At least one seal is formed on the inside surface of the coupling body. The at least one seal includes a proximal seal adjacent the shoulder portion. A ring is annularly disposed on the coupling body urging the at least one seal into the fluid conduit to seal and mechanically connect the coupling body to the fluid conduit.

In accordance with another aspect, a fitting for making connections with a pipe includes a coupling body having an inside surface defining a bore for receiving a pipe. A radial section is defined along the inside surface to limit axial insertion of the pipe. A ring is fitted over the coupling body for sealing and mechanically connecting the coupling body to the pipe. An axisymmetrical main seal is formed on the inside surface of the coupling body that seals and connects to the pipe when the ring is installed on the coupling body. An axisymmetrical inboard seal is formed on the inside surface of the coupling body. The inboard seal is located adjacent the radial section and is axially spaced from the main seal. The inboard seal seals and connects to the pipe when the ring is installed on the coupling body. An axisymmetrical outboard seal is formed on the inside surface of the coupling body. The outboard seal is axially spaced from the main seal and seals and connects to the pipe when the ring is installed on the coupling body.

In accordance with yet another aspect, a fitting for making connections with a pipe includes a coupling body having an inside surface defining a bore for receiving a pipe, a shoulder for limiting axial insertion of the pipe, and a plurality of seals extending into the bore from the inside surface. A swage ring is fitted over the coupling body for sealingly and mechanically connecting the plurality of seals with the pipe. The plurality of seals includes a circumferentially continuous main seal spaced axially inward relative to a distal end of the coupling body and a circumferentially continuous inboard seal spaced axially inward relative to the main seal and closely adjacent the shoulder.

DETAILED DESCRIPTION

Referring now to the drawings wherein the showings are for purposes of illustrating one or more exemplary embodiments and are not to be construed as limiting the invention, a fitting having a low volume crevice is shown for coupling two sections of tube or pipe together and generally designated by reference numeral10. With specific reference toFIG. 1, the fitting10includes a coupling or coupling body12and at least one swage ring. in the illustrated embodiment, two swage rings14,16are shown and can be used to couple two sections of coaxial tubing or pipe together (only one pipe, pipe18, is shown). As illustrated, the components12,14,16of the fitting10are generally axisymmetrical about axis20. In the illustrated embodiment ofFIG. 1, as will be described in more detail below, swage ring14is shown in a fully installed position coupling the fitting10to pipe18and swage ring16is shown in a partially installed, shipping ready position, prior to coupling to a pipe.

The coupling body12, also referred to herein as a connector body, of the illustrated fitting10includes first portion or sleeve12a(which forms the left side of the coupling body inFIG. 1) and a second portion or sleeve12b(which forms the right side of the coupling body inFIG. 1). The first sleeve12ais adapted to receive the first section of tube or pipe18and the second sleeve12bis adapted to receive the second section of tube or pipe (not shown). As will be described in more detail below, when the swage rings14,16are axially forced onto respective sleeves12a,12bwith the tube or pipe sections received therein, the sleeves become mechanically connected to and sealed with the received tube or pipe sections.

In one exemplary embodiment, the coupling body12and the swage rings14,16are formed of stainless steel and used in conjunction with a tube or pipe formed of stainless steel. As will be appreciated and understood by those skilled in the art, the coupling body12and swage rings14,16could alternately be formed of any of a variety of other fitting materials, including for example carbon steel, 90/10 copper nickel, 70/30 copper nickel. Likewise, the tube or pipe could be formed of a variety of other materials.

Additionally, those skilled in the art will understand and appreciate that the exact configuration of the fitting10can vary and need not include exactly two sleeves in a coaxial configuration, as shown in the illustrated embodiment. For example, the fitting10could be integrally formed or adapted to connect with another component or type of fitting, and may have any number of sleeves extending at various locations therefrom for connecting to one or more corresponding tubes. A particular example could be a combination fitting and ball-valve wherein the fitting10is combinable with a ball-valve in a similar manner as described in commonly owned U.S. Pat. No. 6,467,752, expressly incorporated herein by reference.

As will also be understood and appreciated by those skilled in the art, the sleeves12a,12bare generally identical, except that they are axially mirrored relative to one another, and first sleeve12awill be the primary sleeve described in further detail herein. In the illustrated embodiment, the sleeve12aincludes a circumferential flange or ridge22extending radially outwardly from exterior outside surface24of the body12. As will be described in more detail below, the ridge22includes a tool engaging surface26which is used in joining the sleeve12ato the adjacent swage ring14when connecting the fitting10to the pipe18received therein. Pipe18can alternately be referred to as a pipe section, tube, tube section or the like. As used herein, the terms “pipe,” “pipe section,” “tube,” and “tube section” are used interchangeably and all such components or elements and their equivalents are to be considered acceptable for use with fitting10.

With additional reference toFIG. 2, the sleeve12aincludes a plurality of spaced apart seals, including main seal30, inboard or proximal seal32and outboard or distal seal34, for sealing between and mechanically connecting the coupling body12to pipe18. The seals30,32,34are each positioned on or extend from interior surface36of the coupling body12. As used herein, the terms “proximal” and “distal”, as well as the terms “inboard” and “outboard”, are used to generally indicate relative axial spacing, such as from the exterior flange22or the sleeve's distal end38. Thus, the distal or outboard seal34is axially spaced relative to the flange22a greater distance than is the proximal or inboard seal32.

The main seal30serves to provide a main fluid seal and mechanical connection with the tube or pipe18, as will be described in more detail below. In the illustrated embodiment, the main seal30includes first tooth40and second tooth42which are axially spaced from and between the circumferential ridge22, also referred to herein as a swage ring stop, and the distal end38of the coupling body12. The two-tooth main seal arrangement is more fully described in commonly-owned U.S. Pat. No. 5,110,163, expressly incorporated herein by reference. The teeth40,42are slightly separated from one another by groove44. It is to be appreciated by those skilled in the art that the main seal30could alternatively be formed as only a single tooth or more than two teeth. A main seal compression land46, also referred to herein as a seal urging feature or projection, is formed on and extends radially from outside surface24adjacent the main seal30. In the illustrated embodiment, the land46is directly opposite the main seal30and includes an abrupt upslope ramp48, a plateau50and a downslope ramp52.

The inboard or proximal seal32is located between the main seal30and the ridge22, axially spaced from each. Like the main seal30, the inboard seal32is adapted to provide a fluid seal and a mechanical connection with the tube or pipe18. In the illustrated embodiment, the inboard seal32is a pair of teeth54,56slightly separated from one by groove58, but it is to be appreciated by those skilled in the art that the inboard seal could be formed by a single tooth or more than two teeth. The proximal seal32is located closely adjacent a stop or shoulder60. The shoulder60, also referred to herein as a radial section, that is closely adjacent the teeth54,56prevents further insertion of the tube18into the fitting and, thus, abuts or is closely adjacent one end18aof the tube18.

An inboard compression land70, also referred to herein as an inboard or proximal seal urging feature or projection, is formed on and extends radially from outside surface24adjacent inboard seal32. In the illustrated embodiment, the land70is positioned directly opposite the inboard seal32and includes an abrupt upslope ramp72, a plateau74and a fairly gradually downslope ramp76. The plateau74is generally radially aligned (i.e., has a substantially similar outer diameter) with the plateau50of the main seal land46. The configuration of the inboard land70, particularly the gradually downsloping ramp76, can have the effect of assisting in or facilitating driving the seals30,32into the pipe18. In the illustrated embodiment, the plateau74is immediately opposite the inboard seal32and the stop60, the ramp72extends from the plateau to the ramp52of the main seal land46at a location centrally positioned between the main seal30and the inboard seal32, and the reverse taper ramp76extends from the plateau74to about the flange22.

The outboard or distal seal34is located between the main seal30and the distal end38, axially spaced from each. Like the seals30,32, the outboard seal34is adapted to provide a fluid seal and a mechanical connection with the pipe18. In the illustrated embodiment, the outboard seal34is a single tooth which can be referred to as the outboard isolation tooth. The outboard isolation tooth34is positioned adjacent the distal end38and axially spaced inwardly slightly therefrom. It is to be appreciated by those skilled in the art that the outboard seal34can alternately be formed of a plurality of teeth, separated from one another by one or more appropriate grooves.

The connector body12of the illustrated embodiment further includes at least one anti-torsion ridge80located between the main seal30and the outboard seal34. In the illustrated embodiment, the at least one anti-torsion ridge80is a single ridge positioned adjacent the outboard isolation tooth34, but axially spaced inwardly therefrom. The torsion ridge80of the illustrated embodiment is primarily provided to carry torsion loads between the connector body12and the pipe18. The anti-torsion ridge80, also referred to herein as a torsion ridge, is spaced axially outwardly from the main seal30a sufficient distance so that a reduction of the diameter of pipe18by the main seal30does not interfere with engagement between the torsion ridge80and the pipe18. The torsion ridge80preferably has friction surfaces (not shown) which can be formed by knurling, broaching or the like to better resist torsion loads. Further details concerning the anti-torsion ridge80and its function are provided in commonly owned U.S. Pat. Nos. 6,692,040 and 6,131,964, both expressly incorporated herein by reference.

As taught in the above-referenced '040 patent, in an alternate embodiment, the outboard isolation tooth34can be replaced and/or serve as a distal torsion ridge, in addition to or in replacement of the torsion ridge80. Similar to and/or with the torsion ridge80, the distal torsion ridge would primarily serve to carry torsion loads between the connector body12and the pipe18. When both are employed, the spacing between the torsion ridge80and the alternate distal torsion ridge is sufficient to prevent pipe reductions caused by either one of the torsion ridges from affecting the other. Like the ridge80, the alternate distal torsion ridge can include a frictional surface formed by knurling, broaching or the like to better resist torsion loads.

Returning to the illustrated embodiment, the outside surface24has a distal portion84between the land46and the distal end38. The distal portion84has a relatively smaller outer diameter than the lands46,70, as well as the flange22. The distal portion84of the connector body12also has an increased friction section86, also referred to as a locking mechanism, adjacent the distal end38. In the illustrated embodiment, the friction section86includes a plurality of ridges88separated from one another by grooves90to better retain the swage ring14on the connector body12once the swage ring14is fully installed on the body12. More particularly, the friction ridges88assist in preventing the swage ring14from slipping or working off the connector body12. Another feature provided adjacent the distal end38is taper92which preferably has a taper angle of about twenty degrees (20°). The taper92assists in initially installing the swage ring14onto the connector body12. Both features86and92are more fully described in the above-incorporated '040 and '964 patents.

With additional reference toFIG. 3, the swage ring14, also referred to herein as a drive ring, is sized to be annularly received over and axially forced along the sleeve12atoward the flange22for urging the seals30,32,34into the pipe18to seal and mechanically connect the body12with the pipe. Like the sleeves12a,12b,ring14will primarily be the ring described in further detail herein. However, it is to be appreciated that ring16is essentially identical and shares like elements. More specifically, in the illustrated embodiment, the swage ring14includes an exterior surface100having a relatively constant outside diameter. The swage ring14further includes an interior surface102defining a throughhole into which the coupling sleeve12ais received when the ring14is installed onto the connector body12(seeFIG. 1). More particularly, the interior surface102includes distal compression surface or portion104positioned adjacent swage ring distal end106. In the illustrated embodiment, the compression surface104includes a plurality of ridges108separated from one another by grooves110, which can be collectively referred to as a friction section or a locking mechanism. The ridges and grooves108,110assist in better retaining the swage ring14on the connector body12when the ring is fully installed on the body12. More particularly, the friction ridges108and grooves110assist in preventing the swage ring14from slipping or working off the distal end38of the connector body12. Preferably, the locking mechanism108,110of the compression portion104cooperates and/or works in conjunction with the locking mechanism88,90of the connector body12.

A tapered surface or portion112connects the distal compression surface104with a proximal compression surface or portion114. As shown, the proximal compression surface has an increased diameter relative to the distal compression surface104. In the illustrated embodiment, the proximal compression surface is formed of a first segment114aadjacent the tapered surface112, a second segment114bspaced further inward relative to the distal end106than the first segment114a,and a kick-down tapered segment114cconnecting the first segment114ato the diametrically larger second segment114b.A proximal taper118of the surface102flares open adjacent proximal end120for facilitating easier insertion of the sleeve12a,and particularly the lands46,70of the sleeve12a,into the throughhole of ring14when the ring is installed onto the body12. In the illustrated embodiment, the angle of the proximal taper118substantially matches the angle of the upslope ramp48(see swage ring16ofFIG. 1) and facilitates axial movement of the swage ring14past the lands46,70.

With reference to the right side ofFIG. 1, the swage ring16is shown partially installed or preassembled on the connector body12(specifically, sleeve12b) in a pre-install or distal position. In this position, swage ring taper112of ring16is adjacent, but slightly spaced relative to, the main seal land ramp48of sleeve12b.Through an interference fit, the swage ring16is maintained and can be shipped to customers in the pre-install position on the connector body12, which facilitates ease of use and installation by the ultimate end-users. In particular, ease of use is facilitated by the fitting10being maintained as a partially assembled one-piece assembly, as opposed to the components of the assembly being multiple pieces separate from one another.

Specifically, the diameter of segment114bof ring16is slightly smaller than the exterior diameter of the distal portion84of sleeve12bso that the interference fit is formed when the swage ring16is axially forced onto the connector body sleeve12bto the pre-install position. Though the interference fit causes the sleeve12bto partially contract radially, a sufficient inner diameter is maintained for all the seals30,32,34and the torsion ridge80so that a pipe can be inserted into the sleeve12b.The sufficient inner diameter is large enough to accommodate a manufacturing tolerance of the fitting body12, to accommodate a manufacturing tolerance of a pipe and to maintain a clearance gap between the sleeve12band its pipe that allows relatively easy insertion of its pipe thereinto.

To fully install the swage ring14or16onto the sleeve12aor12bwith a pipe, such as the pipe18, inserted therein for purposes of mechanically connecting and sealing the fitting10to the pipe, an installation tool (not shown) can be used to further force the swage ring onto its sleeve toward the tool engaging flange22. One suitable installation tool is described in commonly-owned U.S. Pat. No. 5,305,510, expressly incorporated herein by reference. As will be known and appreciated by those skilled in the art, the installation tool has opposed jaws that engage the tool engaging surface26of the flange22and the swage ring distal end106and are actuated to force or press the swage ring toward the flange to a final installation position (such as swage ring14is shown inFIG. 1). Axial movement of the swage ring onto the connector body12with the pipe inserted therein causes radial movement of the fitting body12, and particularly the seals30,32,34of the sleeve, toward or into the pipe to create seals and mechanical connections therewith.

More specifically, when ring14is installed onto the connector body sleeve12a,the inboard seal land70is engaged by the proximal compression surface114of a swage ring14so that the proximal seal32is urged or compressed into sealing engagement with the pipe18. When the swage ring14is moved onto the connector body12toward flange22, the main seal30is also urged or compressed inwardly against the pipe18by compression forces from compression surface114of the swage ring14. More particularly, the compression surface114engages the main seal land46to compress inwardly the main seal30into the pipe18. The proximal torsion ridge80is also urged or compressed inwardly into the pipe18by surface104of the swage ring14. Like the torsion ridge80, the outboard isolation tooth34is also urged or compressed inwardly into the pipe18by the distal surface104when the swage ring14is installed onto the connector body12.

Preferably, the design of the connector body10is such that when the swage ring14is urged over the coupling body12, the main seal30is urged into substantial biting and sealing engagement with the outer surface of the tube18. This sealing is caused when the surface114engages the land46. The isolation tooth34and the proximal seal32are each designed to make at least a minimal bite into the outer surface of the tube18. Preferably, the connector body12is configured so that the proximal seal32bites into the tube18an amount less than the isolation tooth34and the isolation tooth34bites into the tube18an amount equal to or less than the amount the main seal30bites into the tube18.

The purpose of the main seal30is to substantially engage the surface of the tube18in order to provide a hermetic seal so that no fluid flowing through the tube18can be released between the seal30and the tube18. When forced by the swage ring14, the seal30bites into the outer surface of the tube18and, simultaneously, the main seal's teeth40,42are possibly deformed so as to fill any of the rough or irregular surface imperfections commonly found on the outside of tube18. The teeth40,42are sufficiently wide and have a profile such that they can resist tensile loading along the axis of the tube18which could occur should there be a force on the tube18which might tend to pull it axially from the connector body12. The outboard isolation tooth34and the proximal seal32serve to prevent pivoting or rocking of the tube18about a fulcrum established where the main seal's teeth40,42bite into the tube18. Accordingly, the tube18is prevented from bending or flexing about the main seal30, thus preventing relative motion between the main seal30and the tube18and thus leakage at the point where the seal30engages the tube18.

When the swage ring14is forced onto the connector body12, distal outside diameter portion84of the connector body12is compressed by distal compression surface104of the swage ring14. As already mentioned, the main seal land46of the connector body sleeve12ais compressed by compression surface114. The reduction in diameters from the segment114bto the segment114aprovides a kick-down effect more fully described in commonly-owned U.S. Pat. No. 5,709,418, expressly incorporated herein by reference. Further details of the sequential loading caused as the swage ring14is axially moved onto the connector body12are provided in the above-referenced applications, all of which have been expressly incorporated herein by reference. Of course, as will be appreciated by those skilled in the art, the fitting10need not include the kickdown feature to achieve the advantages of the low volume crevice. Thus, in alternate embodiment, the fitting10could be formed without the kickdown feature.

The close location of the proximal seal32relative to the shoulder60reduces or limits a crevice volume defined between the coupling body12and the tube18. More particularly, although not visible in the FIGURES, there is a gap, space or area between the end of the tube18and the shoulder60that forms the crevice volume. As shown, when the connector body is machined a small radius130is disposed between the inner tooth56of the proximal seal32and the stop60which blends the tooth56into the stop60. When the swage ring14is fully moved onto the connector body12, the engagement between the proximal surface114of the swage ring14and the proximal land70forces the teeth54,56into the tube18, as already mentioned, and also forces the connector body12around the teeth54,56at location132into the tube18. As a result, the radius130moves radially into the tube18and forms a sealing surface with the tube18. Thus, the crevice volume is sealed off by the engagement of the radius130with the tube18and the engagement of the proximal seal32with the tube18.

Fluid or any other substance passing through the tube18into the fitting10or from the fitting10into the tube18can, if small enough, occupy the crevice volume. However, by positioning the proximal seal32as close as possible to the shoulder60and/or the end18aof the pipe18, the crevice volume is reduced or made as small as possible. As a result, in one exemplary embodiment, the proximal seal32is immediately adjacent the shoulder60, i.e., as close as possible without detrimentally affecting the sealing ability of the proximal seal32. In contrast, with reference toFIG. 4, a fitting of Applicant Lokring Technology Corporation is shown that does not include a shoulder adjacent a proximal sealing tooth. The fitting10′ includes a connector body12′ and a swage ring14′ for connecting to a pipe18′. The connector body12′ includes no shoulder and a proximal seal32′ is spaced apart from a pipe end18a′.In this arrangement, the crevice volume CV is relatively large ending axially between the pipe18′ and the connector body12′ from pipe end18a′to proximal seal32′.

in an alternate embodiment, a non-metallic material such as an elastomeric material is placed between the end of the tube18and the shoulder60to form a sealing gasket. The gasket could further reduce and/or eliminate the crevice volume between the fitting and the tube18. In an exemplary arrangement, the gasket material could be captively held in position on the fitting when the fitting is manufactured.