HK1228488B - Split ring coupling - Google Patents

Description

Split ring couplings

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application and claims priority to U.S. Provisional Patent Application No. 61/920,138, filed on December 23, 2013, which is hereby incorporated by reference herein.

Technical Field

The present invention relates to mechanical pipe couplings for joining pipe elements in end-to-end relationship.

Background Art

Prior art mechanical couplings for joining pipe elements end-to-end include interconnectable segments that can be positioned circumferentially around the end portions of coaxially aligned pipe elements. As used herein, the term "pipe element" is used to describe any tubular object or component having a tubular form. Pipe elements include pipe handles, pipe fittings (such as elbows, caps, and tees), and fluid control components (such as valves, pressure reducers, filters, restrictors, pressure regulators, etc.).

Each mechanical coupling segment comprises a housing having an arcuate surface that projects radially inwardly from the housing and engages a flat-end pipe element, a shoulder-end pipe element, a shoulder and bead pipe element, or a circumferential groove extending around each of the pipe elements to be connected. The engagement between the arcuate surface and the pipe elements provides mechanical constraint to the coupling and ensures that the pipe elements remain connected, even under high internal pressure and external forces. The housing defines an annular channel that receives a gasket or seal, typically an elastomeric ring, which engages the ends of each pipe element and cooperates with the segment to provide a fluid-tight seal. The segment has a connecting member, typically in the form of a lug that projects outwardly from the housing. The lug is adapted to receive fasteners, such as nuts and bolts, which can be adjustably tightened to pull the segments toward each other.

To ensure a good fit between the coupling and the pipe element, the arcuate surface on prior art couplings has a radius of curvature that substantially matches the radius of curvature of the outer surface of the pipe element with which it is intended to engage. For couplings used with grooved pipe elements, the radius of curvature of the arcuate surface is smaller than the radius of curvature of the outer surface of the pipe element outside of the groove so that the arcuate surface fits properly within and engages the groove.

When using mechanical couplings, the geometric relationship between the curved surface of the coupling and the outer surface of the pipe element in the prior art couplings leads to a time-consuming installation process. Typically, the coupling is received by a technician when the segments are screwed together and the ring seal is fixed in the channel of the segment. The technician first disassembles the coupling by removing the bolts of the coupling, removes the ring seal, lubricates it (if not lubricated in advance), and places it around the end of the pipe element to be connected. The installation of the ring seal requires it to be lubricated and significantly stretched to adapt to the pipe element, a generally difficult and cumbersome task because the ring seal is generally rigid and lubrication makes manual manipulation of the seal difficult. When the ring seal is in the right position on the two pipe elements, then one by one the segments are placed to straddle the end of the pipe element and fix the ring seal relative to them. During placement, the segments engage the seal, the arcuate surface aligns with the groove (when present), or with alignment marks made on the outside surface of the pipe element, a bolt is inserted through the lug, a nut is threaded onto the bolt and tightened, and the coupling segments are pulled toward each other, compressing the seal and engaging the arcuate surface within the groove.

As is apparent from the foregoing description, installation of mechanical pipe couplings according to the prior art requires a technician to typically manipulate at least seven separate parts (and more parts when the coupling has more than two segments) and must completely disassemble and reassemble the coupling. If a technician could install a mechanical pipe coupling without first completely disassembling the mechanical pipe coupling piece by piece and then reassembling it, a significant amount of time, effort, and expense would be saved.

Summary of the Invention

The present invention relates to a coupling for connecting pipe elements in an end-to-end relationship. In an exemplary embodiment, the coupling includes a plurality of segments attached to each other end-to-end in a spaced-apart relationship. The segments surround a central space for receiving the pipe elements. Each of the segments has a channel extending between the ends. Each of the segments has a first and a second groove extending between the ends. The grooves are positioned on opposite sides of the channel in a spaced-apart relationship. Each of the grooves is defined by two side surfaces arranged in a spaced-apart relationship and a base surface extending therebetween. Each base surface includes a first and a second surface portion arranged at opposite ends of the segment and a third surface portion positioned therebetween. The first and second surface portions each have a larger radius of curvature than the third surface portion. The exemplary coupling also includes a first open ring and a second open ring, the first open ring being positioned within the first groove and the second open ring being positioned within the second groove. The first and second open rings engage the first and second surface portions of the base in the first and second grooves and support the segments in a spaced-apart relationship.

In a specific exemplary embodiment, at least one of the split rings has an outer radius of curvature and an inner radius of curvature. In this example, the inner radius of curvature is at least equal to the outer radius of the tubular element. Also in this example, the radius of curvature of the first and second surface portions on at least one of the segments is substantially equal to the outer radius of curvature of the at least one split ring.

In an exemplary embodiment, at least one of the split rings supports the segments in a preassembled state, wherein the segments are supported on the at least one split ring in a spaced relationship sufficient to allow insertion of the tubular element into the central space. In this exemplary embodiment, the at least one split ring has sufficient rigidity to maintain the segments in the preassembled state by operating the coupling during insertion of the tubular element.

As an example, at least one of the first and second surface portions has a length extending from about 5% to about 30% of the total length of at least one of the grooves. In yet another example, at least one of the split rings has a rectangular cross-sectional shape. In another example embodiment, at least one of the split rings includes a plurality of teeth arranged in a spaced relationship with one another. The teeth extend circumferentially around the at least one split ring and project toward the center of the central space.

According to another exemplary embodiment, the coupling further comprises a seal positioned within the passageway of the segments. As an example, the seal comprises a flexible, resilient ring having an inner ring surface adapted to engage the outer surface of the pipe element. The inner ring surface has a diameter sized to receive the pipe element when the pipe element is inserted between the segments.

In a specific example embodiment, the ring inner surface includes first and second lips extending circumferentially around the ring. The lips are positioned in a spaced relationship on opposite sides of the ring and project substantially inwardly toward each other. The lips are adapted to engage the tubular element and form a fluid-tight seal when the ring is compressed by the segments. By way of example, the first and second lips each have a tapered surface facing outward from the ring. The tapered surfaces have a width sized to engage and guide the tubular element between the segments when the tubular element is inserted therebetween.

In an exemplary embodiment, the sealing member includes a rear wall and first and second side walls positioned in spaced relation on opposite sides of the ring. The side walls extend substantially radially inward from the rear wall. A first lip is attached to the first side wall, and a second lip is attached to the second side wall. A tongue is attached to the rear wall. The tongue extends circumferentially around the ring. In this exemplary embodiment, the tongue is positioned between the first and second lips and projects substantially radially inward. The tongue engages the end of the tubular element when inserted between the segments.

As another example, the segments include adjustably tightenable connecting members for pulling the segments toward the central space. The adjustably tightenable connecting members include a plurality of fasteners. The fasteners extend between the segments and hold the segments together in a pre-assembled state, wherein the segments are supported on at least one split ring.

The exemplary embodiment further includes at least one first angularly oriented surface located on a first one of the segments and at least one second angularly oriented surface located on a second one of the segments. When the fastener is tightened to bring the first and second angularly oriented surfaces into contact, the first and second angularly oriented surfaces are in a facing relationship and slide over each other. The sliding motion between the first and second angularly oriented surfaces causes the first and second segments to rotate in opposite directions relative to each other.

In another exemplary embodiment, a coupling for connecting tubular elements in an end-to-end relationship includes a plurality of segments attached end-to-end in a spaced relationship around a central axis and defining a central space for receiving the tubular element. Each of the segments has a channel defined by a rear wall extending between the ends of the segment. Each of the rear walls has a surface facing the central axis. Each of the segments has first and second grooves extending between the ends. The grooves are positioned on opposite sides of the channel in a spaced relationship. Each of the grooves is defined by two side surfaces arranged in a spaced relationship and a base surface extending therebetween. Each of the base surfaces faces the central axis. A first split ring is positioned within the first groove and a second split ring is positioned within the second groove of the segment. At least one of the first and second split rings engages at least one of the base surfaces in at least one of the first and second grooves near an end of at least one segment, thereby supporting the segment in a spaced relationship. For the at least one segment, a distance between a surface of the rear wall and a surface of the base, as measured along a line projecting radially from the central axis, is a first value at a first point midway between ends of the at least one segment and is a second value at a second point proximal to at least one of the ends of the at least one segment. The first value is greater than the second value.

As an example, a coupling for connecting tubular elements in an end-to-end relationship includes a plurality of segments attached to each other in a spaced-apart relationship end-to-end and surrounding a central space for receiving the tubular elements. Each of the segments has a channel extending between the ends. Each of the segments has at least one groove extending between the ends. The at least one groove is positioned adjacent to the channel. The at least one groove is defined by two side surfaces arranged in a spaced-apart relationship and a base surface extending therebetween. The base surface includes first and second surface portions, respectively arranged at opposite ends of the segments, and a third surface portion positioned therebetween. In this example embodiment, the first and second surface portions each have a larger radius of curvature than the third surface portion. A split ring is positioned within the at least one groove. The split ring engages the first and second surface portions of the base and supports the segments in a spaced-apart relationship.

In a specific exemplary embodiment, the split ring has an outer radius of curvature and an inner radius of curvature, the inner radius of curvature being at least equal to the outer radius of the pipe element, and the first and second surface portions on at least one of the segments have a radius of curvature substantially equal to the outer radius of the split ring.

In an example embodiment, the split ring supports the segments in a preassembled state, wherein the segments are supported on the split ring in a spaced relationship sufficient to allow insertion of the pipe element into the central space. In a specific example embodiment, the split ring has sufficient rigidity to maintain the segments in the preassembled state by operating the coupling during insertion of the pipe element.

As an example, at least one of the first and second surface portions has a length extending from about 5% to about 30% of the total length of at least one of the grooves. In yet another example, the split ring has a rectangular cross-sectional shape. In another example, the split ring includes a plurality of teeth arranged in a spaced relationship with one another and extending circumferentially around the split ring. In this example, the teeth protrude toward the center of the central space.

The present invention also encompasses a coupling for connecting tubular elements in an end-to-end relationship. In another exemplary embodiment, the coupling includes a plurality of segments attached end-to-end to each other in a spaced-apart relationship and surrounding a central space for receiving the tubular element. Each of the segments has a channel extending between the ends. Each of the segments has a first and a second groove extending between the ends. The grooves are positioned on opposite sides of the channel in a spaced-apart relationship. Each of the grooves is defined by two side surfaces arranged in a spaced-apart relationship and a base surface extending therebetween. Each base surface includes a first and a second surface portion, respectively arranged at opposite ends of the segment, and a third surface portion positioned therebetween. The first and second surface portions each have a center of curvature offset from the center of curvature of the third surface portion. A first open ring is positioned within the first groove, and a second open ring is positioned within the second groove. The first and second open rings engage the first and second surface portions of the base in the first and second grooves and support the segments in a spaced-apart relationship.

In a specific exemplary embodiment, at least one of the split rings has an outer radius of curvature and an inner radius of curvature. The inner radius of curvature is at least equal to the outer radius of the tubular element. In this exemplary embodiment, the first and second surface portions of at least one of the segments have respective radii of curvature that are substantially equal to the outer radius of curvature of the at least one split ring.

In another exemplary embodiment, at least one of the split rings supports the segments in a pre-assembled state, wherein the segments are supported on the at least one split ring in a spaced relationship sufficient to allow insertion of the pipe element into the central space.

As an example, the at least one split ring has sufficient rigidity to maintain the segments in a pre-assembled state by operating the coupling during insertion of the pipe element.

In an example embodiment, at least one of the first and second surface portions has a length extending from about 5% to about 30% of a total length of at least one of the trenches.

In a specific example embodiment, at least one of the split rings has a rectangular cross-sectional shape. In another example embodiment, at least one of the split rings includes a plurality of teeth arranged in a spaced relationship with one another. The teeth extend circumferentially around the at least one split ring. The teeth protrude toward the center of the central space.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an axial view of an example pipe coupling according to the present invention;

FIG1A is an isometric exploded view of the pipe coupling shown in FIG1 ;

FIG2 is an isometric view of a segment from the pipe coupling shown in FIG1 ;

FIG3 is a partial cross-sectional view of the pipe coupling shown in FIG1 ;

3A is a partial cross-sectional view of an example embodiment of a pipe coupling according to the present invention;

FIG3B is an isometric view of a segment from the pipe coupling shown in FIG3A ;

3C, 3D and 3E are cross-sectional views of example embodiments of coupling segments according to the present invention;

4 and 5 are axial views of another exemplary embodiment of a pipe coupling according to the present invention;

FIG5A is a longitudinal sectional view of the pipe coupling shown in FIG4 and 5;

6 and 7 are isometric views of example seals for use with pipe couplings according to the present invention;

8-10 are longitudinal sectional views illustrating a method of using a pipe coupling according to the present invention; and

11 is an axial view of an example coupling according to the present invention.

DETAILED DESCRIPTION

Fig. 1 and 1A illustrate an example coupling 10 according to the present invention. Coupling 10 comprises a plurality of segments, in this example, two segments 12 and 14 are attached to each other end to end around a central space 16. As shown in Fig. 2, each (showing 12) in segments 12 and 14 has a channel 20, which extends between the end 22 and 24 of the segment. Each segment 12 and 14 also has a first and a second groove 26 and 28. Grooves 26 and 28 extend between the end 22 and 24 of the segment and are positioned on the opposite side of the channel 20 with a relationship spaced apart from each other. Each groove 26 and 28 is limited by two side surfaces 30 and 32 arranged with a relationship spaced apart and a base surface 34 extending between the side surfaces. As shown in Figs. 2 and 3, base surface 32 comprises three surface portions 36, 38 and 40. The first and second surface portions 36 and 38 are arranged at the opposite ends 22 and 24 of segments 12 and 14, respectively. The third surface portion 40 is positioned between the first and second surface portions 36 and 38. Each of the first and second surface portions 36 and 38 has a respective radius of curvature 42 and 44, and these radii are greater than the radius of curvature 46 of the third surface portion 40. The first and second surface portions 36 and 38 advantageously have a length of from about 5% to about 30% of the total length of one of the grooves 26, 28.

As shown in Figures 1, 1A, and 3, the coupling 10 includes first and second split rings 48 and 50. Split ring 48 is positioned within groove 26 of segments 12 and 14 and split ring 50 is positioned within groove 28. Referring to Figure 3, the split ring (shown as 48) has an outer radius of curvature 52 and an inner radius of curvature 54. In their undeformed state, the outer radius of curvature 52 of the split ring is dimensioned so that the split rings 48 and 50 engage the first and second surface portions 36 and 38 of the base surface 34 and thus support the segments 12 and 14 in a spaced relationship sufficient to allow the pipe element to be inserted into the central space 16, as described in detail below. This spaced configuration of the segments (shown in Figures 1 and 3) is referred to as a "pre-assembled state," and the rigidity of the split rings 48 and 50 is sufficient to maintain the segments 12 and 14 in this pre-assembled state during transportation, handling, and assembly of the coupling. Advantageously, the radii of curvature 42 and 44 of the first and second surface portions 36 and 38 of the base surface 34 of the grooves 26 and 28 are substantially equal to the radii of curvature of the split rings 48 and 50 in their undeformed state. Further to this end, when in their undeformed state, the inner radius of curvature 54 of the split rings 48 and 50 is sized to be at least as large as the maximum radius of the pipe elements to be joined by the coupling 10. This allows the pipe elements to be inserted into the central space 16 when the coupling 10 is in its pre-assembled state as described below.

In the pre-assembled state, as shown in FIG1 , the segments 12 and 14 are attached to each other end to end around the central space 16 and supported in a spaced relationship with each other sufficient to allow a pipe element to be inserted between the segments 12 and 14 into the central space 16. The interconnection of the segments 12 and 14 is achieved by connecting means, which are preferably in the form of lugs 56 and 58 shown in FIG1 and 2 . The lugs are preferably located at each end of each segment and project outwardly from the segment. The lugs 56 and 58 are positioned facing each other and are adapted to receive fasteners, preferably in the form of bolts 60 and nuts 62, which can be adjustably tightened and cooperate with the lugs 56 and 58 for adjustably connecting the coupling segments to each other, as discussed in more detail below. While the rigidity of the split rings 48 and 50 is sufficient to support the segments 12 and 14 in their spaced relationship in the pre-assembled state, it is not so great that it prevents the use of hand tools to tighten the bolts 60 and nuts 62 to pull the segments 12 and 14 toward the central space 16, thereby deforming the split rings to a point where their outer radius 52 is smaller and substantially equal to the radius of the third surface portion 40 of the grooves 26 and 28. The inner radius 54 becomes even smaller as the split rings deform to allow them to engage the grooves in the pipe elements and provide a mechanical engagement between the coupling 10 and the pipe elements to hold the pipe elements to the coupling against externally applied forces and forces resulting from internal pressure within the pipe elements (which would tend to cause separation of the connection). (Other types of pipe elements, such as shouldered and shoulder and bead pipe elements, can also be effectively engaged by the inner radius 54.) When used with grooved pipe elements, it is advantageous for the split rings to have a rectangular cross-sectional shape (as shown in FIG. 1A ) to provide a substantially continuous engagement within the grooves. In another coupling embodiment 64 shown in Figures 4, 5 and 5A, a split ring 66 includes a plurality of teeth 68. The teeth 68 are arranged in a spaced relationship and extend circumferentially around the split ring 66. The split ring 66 is advantageously used with a flat-end pipe element. The teeth 68 protrude toward the center 60 of the central space, and when the split ring 66 is deformed by tightening the bolts 60 and nuts 62 to pull the segments 12 and 14 toward the central space 16, it is forced to engage with the outer surface of the flat-end pipe. The teeth bite into the pipe element to provide the desired mechanical engagement to secure the pipe element to the coupling. It is expected that the use of any type of split ring (with teeth or a rectangular cross section) provides special rigidity to the pipe coupling. The segments are advantageously formed of metal (such as iron), and the split ring can be formed of spring steel, stainless steel, beryllium copper, and a polymer (such as nylon and acrylonitrile butadiene styrene (ABS)) including plastic.

Fig. 3A and 3B illustrate another example coupling member 11 according to the present invention. Similar to coupling member 10, coupling member 11 comprises a plurality of segments, in which two segments 13 and 15 are attached to each other end to end around a central space 17. As shown in Fig. 3B, each of segments 13 and 15 (showing 13) has a channel 21, which extends between the end 23 and 25 of the segment. Each segment 13 and 15 also has a first and a second groove 27 and 29. Grooves 27 and 29 extend between the end 23 and 25 of the segment and are positioned on the opposite side of channel 21 with a relationship spaced apart from each other. Each groove 27 and 29 is defined by two side surfaces 31 and 33 arranged with a relationship spaced apart and a base surface 35 extending between the side surfaces. As shown in Fig. 3A and 3B, base surface 35 comprises three surface portions 37, 39 and 41. The first and second surface portions 37 and 39 are arranged at the opposite ends 23 and 25 of segments 13 and 15, respectively. The third surface portion 41 is positioned between the first and second surface portions 37 and 39. Each of the first and second surface portions 37 and 39 has a respective center of curvature 43 and 45, and these centers of curvature are offset from (i.e., do not coincide with) the center of curvature 47 of the third surface portion 41. The first and second surface portions 37 and 39 advantageously have a length of from about 5% to about 30% of the total length of one of the grooves 27, 29.

Similar to coupling 10, coupling 11 includes first and second split rings 49 and 51 (shown at 49). Split ring 49 is positioned within groove 27 of segments 13 and 15, and split ring 51 is positioned within groove 29 (see FIG3B). Referring to FIG3A, split rings (shown at 49) have an outer radius of curvature 53 and an inner radius of curvature 55. In their undeformed state, the outer radius of curvature 53 of the split rings is sized so that the split rings 49 and 51 engage the first and second surface portions 37 and 39 of the base surface 35 and, thus, support segments 13 and 15 in a spaced-apart relationship sufficient to allow insertion of a pipe element into central space 17, as described in detail below. This spaced-apart configuration of the segments (shown at FIG3A) is referred to as a "pre-assembled state," and the rigidity of the split rings 49 and 51 is sufficient to maintain segments 13 and 15 in the pre-assembled state during transportation, handling, and assembly of the coupling. It is advantageous if the radii of curvature 42 and 44 of first and second surface portions 37 and 39 of base surface 35 of grooves 27 and 29 are substantially equal to the radii of curvature of split rings 49 and 50 in their undeformed state. Further to this end, when in their undeformed state, the inner radius of curvature 55 of split rings 49 and 51 is dimensioned to be at least as large as the maximum radius of the pipe elements to which coupling 11 is intended to be joined. This allows the pipe elements to be inserted into central space 17 when coupling 11 is in its preassembled state, as described below. Note that for coupling 11, unlike coupling 10, the radii of curvature of first and second surface portions 37 and 39 have no necessary relationship to the radius of curvature of third surface portion 41, in which the radii of curvature 42 and 44 of surface portions 36 and 38 are greater than the radius of curvature 46 of third surface portion 40.

3C , an exemplary coupling segment 21 according to the present invention can also be described by the geometric relationship between the rear wall 23 extending between the ends of the segment and defining the channel 25, and the base surface 27 of the groove 29, which receives the split ring (not shown). The geometric relationship that allows the opening to support the segment 21 in a spaced relationship as described above is related to a first distance 31 measured between the surface of the rear wall 23 and the base surface 27 of the groove 29 along a radially projecting line 33 between the central axis 35 (e.g., the longitudinal axis of the pipe elements joined by the segment) and a point 37 midway between the ends of the segment 21, and a second distance 39 measured between the surface of the rear wall 23 and the base surface 27 of the groove 29 along a radially projecting line 41 between the central axis 35 and a point 43 near one end of the segment 21. For the segment according to the invention, the value of the first distance 31 is greater than the value of the second distance 39 .

This geometry can be achieved, for example, as shown in FIG3C , by continuously changing the curvature of the base 27 as it traverses between points 37 and 43. In another example, shown in FIG3D , the curvature of the base 27 changes abruptly in an area near the ends of the segments 21. FIG3E shows a base 28 formed of faceted, straight segments in an area near the ends of the segments to receive split rings for supporting the segments in spaced relation.

Fig. 6 and 7 illustrate the example of the seal that uses together with coupling 10,11 and 64 according to the present invention.Seal 72 (Fig. 6) is preferably a flexible, resilient ring, which is formed by elastomeric material.This seal can have lip 74, and lip 74 uses the internal pressure in the pipe to increase the sealing force between seal and the pipe element outer surface.As shown in Fig. 7, another seal embodiment 76 can also have the tongue 78 that is positioned between lip 74, and this tongue extends circumferentially around seal and protrudes radially inward.Tongue 78 provides stop surface, and this stop surface engages the end of pipe element, to ensure the suitable positioning of seal 76 relative to pipe element.The engagement of pipe element and tongue 78 also realizes the alignment of pipe engagement surface and groove (if existing) or with the alignment mark on the pipe element outer surface.Seal 72 and 76 are received in the passage 20 (seeing Figure 1A and 2) of coupling 10 and 64.

The assembly of the pipe coupling is illustrated in Figures 8-10. As shown in Figures 8 and 9, after both pipe elements 80 and 82 are inserted into the coupling 10, the nut 62 is tightened (see Figure 1 again). The nut 62 cooperates with its bolt 60 to pull the segments 12 and 14 toward the central space 16. Tightening the nut exerts a force on the lugs 56 and 58, which compresses the split rings 48 and 50 and causes them to deform so that they engage the outer surfaces of the pipe elements 80 and 82 within the grooves 84 and 86. For plain-end pipes (see Figures 4 and 5), the compression of the split ring 66 causes its teeth 68 to bite into the outer surfaces of the pipe elements. The deformation of the split rings 48 and 50 is preferably substantially elastic, allowing them to substantially rebound to their original shape when the nut is loosened, thereby allowing the coupling 10 to be reused in accordance with the invention described herein. The split rings can also be designed to have significant plastic deformation, wherein the deformation gives the rings a permanent set. For a practical coupling, there will generally be some degree of both plastic and elastic deformation in the split ring due to tightening of the fasteners. The seal 72 is also deformed by this process, with the lip 72 fully engaging the outer surface of the pipe element. Because the seal 72 is essentially volumetrically incompressible, it must be provided with space into which it can expand when radially compressed by the segments.

The rigidity of the joint can be increased using coupling segments 71 and 73 as shown in Figure 11. In addition to having grooves and split rings as described above, segments 71 and 73 also have angularly oriented surfaces 75 (on segment 71) and 77 (on segment 73). Surfaces 75 and 77 in this example are located near connecting members 79 and 81. Surface 75 on segment 71 is in a corresponding facing relationship with surface 77 on segment 73. When nut 83 is tightened on bolt 85, segments 71 and 73 are pulled toward each other and contact so that surface 75 engages surface 77 and slides over surface 77. Because the slopes of surfaces 75 and 77 are opposite to each other on opposite ends of the joint, the sliding motion between the surfaces causes segments 71 and 73 to rotate relative to each other in opposite directions about axis 87 and forces split rings (not shown) to engage the side surfaces of the grooves in which they are received, thereby increasing the rigidity of the joint.

As shown in Figures 1 and 3, for the preassembled coupling 10, it is advantageous to retain the nut 62 on the bolt 60 in a position that will maintain the segments 12 and 14 in the desired spaced relationship through contact between the segments and the split rings 48 and 50.

Claims (45)

1. A connector for connecting pipe elements end-to-end, the connector comprising: Multiple segments are attached end-to-end in a spaced-apart relationship to each other and surround a central space for receiving the tubular element. Each segment has a channel extending between the ends and a first and second groove extending between the ends. The grooves are positioned on opposite sides of the channel in a spaced-apart relationship. Each groove is defined by two side surfaces arranged in a spaced-apart relationship and a base surface extending therebetween. Each base surface includes first and second surface portions respectively disposed at opposite ends of the segment and a third surface portion positioned therebetween. The first and second surface portions each have a larger radius of curvature than the third surface portion. A first open ring and a second open ring, the first open ring being positioned within a first groove and the second open ring being positioned within a second groove, the first and second open rings engaging the first and second surface portions of the substrate in the first and second grooves. 2. The connector according to claim 1, wherein the first and second open rings support the segment in the spaced-out relationship. 3. The connector according to claim 1, wherein: At least one of the open rings has an outer radius of curvature and an inner radius of curvature, wherein the inner radius of curvature is at least equal to the outer radius of the tube element. 4. The connector according to claim 3, wherein the radius of curvature of the first and second surface portions on at least one of the segments is substantially equal to the outer radius of curvature of the at least one open ring. 5. The connector of claim 1, wherein at least one of the open rings supports the segment in a pre-assembled state in a spaced-apart relationship, sufficient to allow the tubular element to be inserted into the central space. 6. The coupling according to claim 5, wherein the at least one open ring has sufficient rigidity to maintain the segment in the pre-assembled state by operating the coupling during insertion of the tubular element. 7. The connector according to claim 1, wherein at least one of the first and second surface portions has a length extending from 5% to 30% of the total length of at least one of the grooves. 8. The connector according to claim 1, wherein at least one of the open rings has a rectangular cross-sectional shape. 9. The connector according to claim 1, wherein at least one of the open rings includes a plurality of teeth arranged in a spaced-apart relationship and extending circumferentially around the at least one open ring, the teeth protruding toward the center of the central space. 10. The connector according to claim 1, further comprising a seal positioned within the channel of the segment. 11. The coupling of claim 10, wherein the seal comprises a flexible, resilient ring having an inner surface adapted to engage the outer surface of the tubular element, the inner surface having a diameter sized to receive the tubular element when it is inserted between the segments. 12. The connector of claim 1, wherein the segment includes an adjustable tightening connecting member for pulling the segment toward the central space. 13. The connector of claim 12, wherein the adjustable ground-tightening connector comprises a plurality of fasteners extending between the segments and holding the segments together in a pre-assembled state. 14. The connector according to claim 13, further comprising: At least one first angled surface, located on the first of the segments; At least one second angled surface, located on the second of the segments, when the fastener is tightened to bring the first and second angled surfaces into contact, the first and second angled surfaces are in a facing relationship and slide over each other, and the sliding movement between the first and second angled surfaces causes the first and second segments to rotate relative to each other in opposite directions. 15. A coupling for connecting pipe elements end-to-end, the coupling comprising: Multiple segments are attached end-to-end in a spaced-apart relationship to each other and surround a central space for receiving the tubular element. Each segment has a channel extending between the ends and at least one groove extending between the ends. The at least one groove is located near the channel and is defined by two side surfaces arranged in a spaced-apart relationship and a base surface extending therebetween. The base surface includes first and second surface portions respectively disposed at opposite ends of the segments and a third surface portion located therebetween. The first and second surface portions each have a larger radius of curvature than the third surface portion. An open ring is positioned within the at least one groove, the open ring engaging the first and second surface portions of the substrate surface. 16. The connector of claim 15, wherein the open ring supports the segment in the spaced-out relationship. 17. The connector according to claim 15, wherein: The open ring has an outer radius of curvature and an inner radius of curvature, wherein the inner radius of curvature is at least equal to the outer radius of the tube element. 18. The connector of claim 17, wherein the radius of curvature of the first and second surface portions on at least one of the segments is substantially equal to the outer radius of curvature of the open ring. 19. The connector of claim 15, wherein the open rings support the pre-assembled segment in a spaced-apart relationship to allow the tubular element to be inserted into the central space. 20. The connector of claim 15, wherein at least one of the first and second surface portions has a length extending from 5% to 30% of the total length of at least one of the grooves. 21. The coupling according to claim 15, further comprising a seal positioned within the channel of the segment. 22. The connector of claim 15, wherein the segment includes an adjustable tightening connection member for pulling the segment toward the central space. 23. A connector for connecting pipe elements end-to-end, the connector comprising: Multiple segments are attached end-to-end in a spaced-apart relationship and surround a central axis and define a central space for receiving the tubular element. Each of the segments has a channel defined by a rear wall extending between the ends of the segment, each of the rear walls having a surface facing the central axis; Each of the segments has first and second grooves extending between the ends, the grooves being positioned on opposite sides of the channel in a spaced-apart relationship, each of the grooves being defined by two side surfaces arranged in a spaced-apart relationship and a base surface extending therebetween, each of the base surfaces facing the central axis. A first open ring and a second open ring, the first open ring being positioned within a first groove, and the second open ring being positioned within a second groove of the segment, at least one of the first and second open rings engaging at least one of the base surfaces near the end of the at least one segment in one of the first and second grooves and thus supporting the segment in a spaced-apart relationship; wherein, for the at least one segment: The distance between the surface of the rear wall and the surface of the base, when measured along a radially projecting line extending from the central axis, has a first value at a first point midway between the ends of the at least one segment, and a second value at a second point near at least one of the ends of the at least one segment, wherein the first value is greater than the second value. 24. The connector of claim 23, wherein the first and second open rings support the segment in the spaced-out relationship. 25. The connector according to claim 23, wherein: At least one of the open rings has an outer radius of curvature and an inner radius of curvature, wherein the inner radius of curvature is at least equal to the outer radius of the tube element. 26. The connector of claim 25, wherein the radius of curvature of the first and second surface portions on at least one of the segments is substantially equal to the outer radius of curvature of the at least one open ring. 27. The connector of claim 23, wherein at least one of the open rings supports the segment in a pre-assembled state in a spaced-apart relationship, sufficient to allow the tubular element to be inserted into the central space. 28. The connector of claim 27, wherein the at least one open ring has sufficient rigidity to maintain the segment in the pre-assembled state by operating the connector during insertion of the tubular element. 29. The connector according to claim 23, wherein at least one of the first and second surface portions has a length extending from 5% to 30% of the total length of at least one of the grooves. 30. The connector according to claim 23, wherein at least one of the open rings has a rectangular cross-sectional shape. 31. The connector of claim 23, wherein at least one of the open rings includes a plurality of teeth arranged in a spaced-apart relationship and extending circumferentially around the at least one open ring, the teeth protruding toward the center of the central space. 32. The connector according to claim 23 further includes a seal positioned within the channel of the segment. 33. The coupling of claim 32, wherein the seal comprises a flexible, resilient ring having an inner surface adapted to engage the outer surface of the tubular element, the inner surface having a diameter sized to receive the tubular element when it is inserted between the segments. 34. The connector of claim 23, wherein the segment includes an adjustable tightening connection member for pulling the segment toward the central space. 35. The connector of claim 34, wherein the adjustable ground-tightening connector comprises a plurality of fasteners extending between the segments and holding the segments together in a pre-assembled state. 36. The connector according to claim 35, further comprising: At least one first angled surface, located on the first of the segments; At least one second angled surface, located on the second of the segments, when the fastener is tightened to bring the first and second angled surfaces into contact, the first and second angled surfaces are in a facing relationship and slide over each other, and the sliding movement between the first and second angled surfaces causes the first and second segments to rotate relative to each other in opposite directions. 37. A connector for connecting pipe elements end-to-end, the connector comprising: Multiple segments are attached end-to-end in a spaced-apart relationship and surround a central axis and define a central space for receiving the tubular element. Each of the segments has a channel defined by a rear wall extending between the ends, each of the rear walls having a surface facing the central axis; Each of the segments has at least one groove extending between the ends of the segment, the at least one groove being located near the channel, and the at least one groove being defined by two side surfaces arranged at intervals and a base surface extending therebetween, the base surface facing the central axis. An open ring, positioned within the at least one groove, engages the base surface at the end of the at least one of the segments near the at least one of the grooves and supports the segments in the spaced-out relationship; wherein, at least for the one segment: The distance between the surface of the rear wall and the surface of the base, when measured along a radially projecting line extending from the central axis, has a first value at a first point midway between the ends of the at least one segment, and a second value at a second point near at least one of the ends of the at least one segment, wherein the first value is greater than the second value. 38. The connector of claim 37, wherein the open ring supports the segment in the spaced-out relationship. 39. The connector according to claim 38, wherein: The open ring has an outer radius of curvature and an inner radius of curvature, wherein the inner radius of curvature is at least equal to the outer radius of the tube element. 40. The connector of claim 39, wherein the radius of curvature of the first and second surface portions on at least one of the segments is substantially equal to the outer radius of curvature of the open ring. 41. The connector of claim 37, wherein the open rings support the pre-assembled segment in a spaced-apart relationship to allow the tubular element to be inserted into the central space. 42. The connector of claim 37, wherein at least one of the first and second surface portions has a length extending from 5% to 30% of the total length of at least one of the grooves. 43. The coupling according to claim 37, further comprising a seal positioned within the channel of the segment. 44. The connector of claim 37, wherein the segment includes an adjustable tightening connection member for pulling the segment toward the central space. 45. A coupling for connecting pipe elements end-to-end, the coupling comprising: Multiple segments are attached end-to-end in a spaced-apart relationship to each other and surround a central space for receiving the tubular element. Each segment has a channel extending between the ends and a first and second groove extending between the ends. The grooves are positioned on opposite sides of the channel in a spaced-apart relationship. Each groove is defined by two side surfaces arranged in a spaced-apart relationship and a base surface extending therebetween. Each base surface includes first and second surface portions respectively disposed at opposite ends of the segment and a third surface portion positioned therebetween. The first and second surface portions each have a center of curvature offset from the center of curvature of the third surface portion. A first open ring and a second open ring, the first open ring being positioned within a first groove and the second open ring being positioned within a second groove, the first and second open rings engaging the first and second surface portions of the substrate in the first and second grooves and supporting the segment in the spaced-out relationship.