Patent Publication Number: US-11662043-B2

Title: Pipe connector cam ring and gripper

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of co-pending U.S. patent application Ser. No. 16/996,544, filed Aug. 18, 2020, entitled “Pipe Connector”. U.S. patent application Ser. No. 16/996,544 is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention pertains to the field of pipe connectors. More particularly, the invention pertains to a pipe connector and a method to connect pipes. 
     Description of Related Art 
     The installation of some pipe connectors requires insertion of an end of a pipe into a body of the pipe connector. To avoid decoupling of the pipe from the pipe connector, some sort of retention mechanism physically holds the pipe end in the body, and to avoid leaks, some sort of sealing mechanism creates a fluid-tight seal between the pipe and the body. The retention mechanism and the sealing mechanism often have separate structural or functional aspects requiring separate implementation, or producing insufficient levels of retention or sealing. 
     One retention and sealing mechanism includes threading the end of the pipe into a threaded portion of the body. This solution requires both threading the pipe and rotating the pipe or the body to seat the connection, a requirement that can be a problem when either or both of the elements cannot be rotated, or if for some reason the pipe cannot be threaded. 
     Another retention and sealing mechanism includes a compression fitting, the use of which includes inserting a pipe through a seal and an externally threaded body, and then rotating an internally threaded collar onto the body to compress the seal against the outside of the pipe. Nothing more than the compression of the seal around the pipe holds the pipe in place though, so that the pipe can pull out of the fitting when fluid pressure is supplied in the pipe. 
     More complex pipe connectors are known, but such connections usually require a plurality of tightening elements, or separate sealing and retention operations that are difficult for one-handed tightening of the connection. 
     SUMMARY OF THE INVENTION 
     A pipe connector to connect to an end of a pipe or pipe fitting provides a single tightening operation to create both a fluid-tight seal and a strong physical connection. 
     In some embodiments, a pipe connector includes a body, a cam ring, a seal element, a push ring, and a gripper. The body has a pocket section, the pocket section having an outer surface, an inner surface around an interior bore, and an aperture passing from the outer surface through the inner surface. The cam ring is configured to be located around the outer surface of the pocket section, the cam ring including an axis, a first axial side, a second axial side opposite the first axial side, a radially outward-facing side, a second attachment element on the radially outward-facing side, a radially inward-facing side, and a cam element extending a circumferential length along a portion of the radially inward facing-side. The cam element includes a first end having a first depth from the inward-facing side toward the outward-facing side and a first axial location relative to the first axial side of the cam ring, and a second end having a second depth and a second axial location relative to the first axial side of the cam ring, the second depth less than the first depth, the second axial location closer to the first axial side of the cam ring than the first axial location. The seal element is configured to be seated around the inner surface of the pocket section. The push ring is configured to be slideably located within the interior bore of the pocket section. The gripper is configured to be located through an aperture in the pocket section and into the first depth of the cam element. The gripper includes a body having a first end and a second end, the first end configured to be located within the first depth of the cam ring, the second end configured to be located within the interior bore of the pocket section and contoured to mate with an outer surface of the pipe. When the body, the cam ring, the seal element, the push ring, and the gripper are assembled, when a pipe is inserted into the pipe connector, and when the cam ring is rotated from a first position toward a second position, the gripper moves from the first axial location to the second axial location to move the push ring against the seal element to seal between the seal element and the pipe, and the gripper moves from the first depth to the second depth to grip the pipe. 
     In some embodiments, a cam ring for a pipe connector includes a first axial side, a second axial side opposite the first axial side, a radially outward-facing side, a radially inward-facing side, and a cam element extending a circumferential length along a portion of the radially inward facing-side. The cam element includes a first cam section at a first end of the circumferential length, the first cam section having a first depth from the inward-facing side toward the outward-facing side, and having a first axial location relative to the first axial side. The cam element also includes a second cam section at a second end of the circumferential length, the second cam section having a second depth from the inward-facing side toward the outward-facing side, and having a second axial location relative to the first axial side, the second depth less than the first depth, the second axial location closer to the first axial side than the first axial location. 
     In some embodiments, a gripper for a pipe connector includes a body and a plurality of teeth. The body has a first side, a second side adjacent the first side, a third side adjacent the first side and opposite the second side, and a fourth side adjacent the second side and the third side and opposite the first side. The plurality of teeth extend from the fourth side of the body, each of the teeth of the plurality of teeth having arc shape to grip a cylinder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG.  1    shows an exploded view of a valve including a pipe connector, according to an embodiment of the invention. 
         FIG.  2    shows a side view of the valve and pipe connector of  FIG.  1   , with the pipe connector in a first position. 
         FIG.  3    shows a cut-through view of the valve and pipe connector of  FIG.  1   , along the lines  3 - 3  in  FIG.  2   . 
         FIG.  4    shows a cut-through view of the valve and pipe connector of  FIG.  1   , along the lines  4 - 4  in  FIG.  2   . 
         FIG.  5    shows a side view of the valve and pipe connector of  FIG.  1   , the pipe connector in a second position. 
         FIG.  6    shows a cut-through view of the valve and pipe connector of  FIG.  1    along the lines  6 - 6  in  FIG.  5   . 
         FIG.  7    shows a cut-through view of the valve and pipe connector of  FIG.  1    along the lines  7 - 7  in  FIG.  5   . 
         FIG.  8    shows a perspective view of the valve and pipe connector of  FIG.  1   . 
         FIG.  9    shows a perspective view of a body of the valve and pipe connector of  FIG.  1   . 
         FIG.  10    shows a perspective view of a cam ring of the pipe connector of  FIG.  1   . 
         FIG.  11    shows a perspective view of a push ring of the pipe connector of  FIG.  1   . 
         FIG.  12    shows a perspective view of a gripper of the pipe connector of  FIG.  1   . 
         FIG.  13    shows a perspective view of a T-bolt assembly of the pipe connector of  FIG.  1   . 
         FIG.  14    shows a perspective view of a retainer ring of the pipe connector of  FIG.  1   . 
         FIG.  15   a    through  FIG.  20   b    show steps of assembling the pipe connector of  FIG.  1   . 
         FIG.  21    shows a cut-through view of the valve and pipe connector of  FIG.  1   , with the pipe connector in the first position. 
         FIG.  22   a    shows a perspective view of the valve and pipe connector of  FIG.  1   , with the pipe connector in the first position. 
         FIG.  22   b    shows a perspective view of the valve and pipe connector of  FIG.  1   , with the cam ring rotating to the second position. 
         FIG.  23   a    shows a perspective view of the cam ring, the gripper, and the push ring of the pipe connector of  FIG.  1    in the first position. 
         FIG.  23   b    shows a perspective view of the cam ring, the gripper, and the push ring of the pipe connector of  FIG.  1   , with the push ring rotating to the second position. 
         FIG.  24   a    shows a cut-through view of the pipe connector of  FIG.  1    in the first position. 
         FIG.  24   b    shows a cut-through view of the pipe connector of  FIG.  1   , with the cam ring rotating to the second position. 
         FIG.  25    shows a side cut-through view of the pipe connector of  FIG.  1   , with the seal element compressed. 
         FIG.  26   a    shows a side cut-through view of the pipe connector of  FIG.  1    in the first position. 
         FIG.  26   b    shows a side cut-through view of the pipe connector of  FIG.  1    in the second position with the gripper holding a pipe. 
         FIG.  27    shows an exploded perspective view of a pipe connector according to an embodiment. 
         FIG.  28    shows a perspective view of a cam ring and a gripper, according to the embodiment of the pipe connector in  FIG.  27   . 
         FIG.  29    shows a perspective view of gripper teeth, according to the embodiment of the pipe connector in  FIG.  27   . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG.  1    shows an exploded view of a valve  100  including a pipe connector  99 , according to an embodiment of the invention, while  FIG.  8    shows a perspective view of the valve  100  and the pipe connector  99  with a pipe  19  inserted into the pipe connector  99 . The pipe connector  99 , while shown integrated as part of the valve  100 , can be implemented as part of a variety of valves, adapters, couplings, or other piping or plumbing fittings and applications. Accordingly, the operational components of the valve  100 , which are not relevant to the inventive pipe connector  99 , are omitted from the drawings and the following description. 
     Components of the Pipe Connector 
     Referring to  FIGS.  1 - 16     b , the pipe connector  99  provides a fluid seal and mechanical connection between a body  1  of the pipe connector  99  and a pipe or conduit  19 . The body  1  is integrated with the valve  100  as shown herein, but may also be integrated with some other sort of device as noted above. 
       FIG.  9    shows a perspective view of the valve  100  and the body  1  of the pipe connector  99 . The valve  100  shown in the figures has a first flange  3  for connection to other components such as a tank or a flanged pipe, and a top cover flange  2  for mounting the operational components of the valve  100 . As noted above, the operational and mounting components are part of the specific valve  100  that is shown in the drawings as an example, and the operational and mounting components do not form part of the novel pipe connector  99 . 
     The body  1  has a pocket section  4  sized substantially congruent to the pipe  19 , with an outer surface  91  facing radially outward, an inner surface  92  facing radially inward, and an interior bore  150  sized to receive a push ring  14  and the pipe  19 , as discussed below. A groove  153  can be provided around, and/or cut into, the inner surface  92  of the pocket section  4  to receive a seal element  13  that ultimately makes a seal between the pipe  19  and the inner surface  92  of the pocket section  4 . An outside groove  198  ( FIG.  19   a   ) can be provided on the outer surface  91  of the pocket section  4  to receive a retainer ring or snap ring  18 , which can be installed after installation of a cam ring  10  to retain the cam ring  10  axially on the outer surface  91 . 
     Apertures  12  pass from the outer surface  91  through the inner surface  92  and are radially arranged around the pocket section  4 . The apertures  12  are sized such that when grippers  8  are inserted, the grippers  8  can move axially toward and away from the open end  24  of the pocket section  4 , but are constrained against movement circumferentially. The drawings show three apertures  12 , but it will be understood that other numbers of apertures could be provided within the teachings of the disclosure. 
     The body  1  or valve  100  is provided with a first attachment element configured to be engaged by a tightening element, which can be operated to grip and seal against the pipe  19 . In the illustrated embodiment, the first attachment element is a bracket  21  adjacent to the pocket section  4 , and the tightening element is an operating bolt assembly including an operating bolt  5 , nuts  6 ,  11 , t-fittings  7 ,  9 , and a washer  10 , as discussed further below. The bracket  21  is pierced by an opening  22  for accommodating an end of the operating bolt assembly. 
       FIG.  10    shows a perspective view of a cam ring  15 . A radially inward-facing side  107  of the cam ring  15  is provided with a plurality of cam elements  230  between a first axial side  103  and a second axial side  104  of the cam ring  15 . The number of cam elements  230  matches the number of apertures  12  in the pocket section  4  of the body  1 . Each cam element  230  extends a circumferential length along a portion of the radially inward-facing side  107  from a first end  101  to a second end  102 . At the first end  101 , each cam element  230  has a first depth  110  from the radially inward-facing side  107  toward a radially outward-facing side  108 . Also at the first end  101 , each cam element  230  has a first axial location  232  relative to the first axial side  103  of the cam ring  15 , a distance  105  from the second axial side  104 . At the second end  102 , each cam element  230  has a second depth  113  from the inward-facing side  107  toward the radially outward-facing side  108 . Also at the second end  102 , each cam element  230  has a second axial location  234  relative to the first axial side  103  of the cam ring  15 , a distance  106  from the second axial side  104 . The second depth  113  is less than the first depth  110 , such that as a gripper  8  moves from the first end  101  to the second end  102 , the gripper  8  is moved radially inward toward the pipe  19 . The second axial location  234  is also closer to the first axial side  103  of the cam ring  15  than the first axial location  232 , such that as a gripper  8  moves from the first end  101  to the second end  102 , the gripper  8  moves toward the first axial side  103  and the seal element  13  to compress the seal element  13 . The gripper  8  moves relative to the cam ring  15  along the circumferential length of the cam element  230  from a first position at the first end  101  to a second position at the second end  102  by rotating the cam element  15 . 
     Each cam element  230  is provided with an entry section  231  at the first end  101  passing between the first axial side  103  of the cam ring  15  and the first axial location  232  to pass a gripper  8  when the cam ring  15  is slid onto the outer surface  91  of the pocket section  4 . 
     The cam ring  15  is provided with a second attachment element on the radially outward-facing side  108  of the cam ring  15  to engage with the tightening element, which when operated, draws the second attachment element toward the first attachment element and rotates the cam ring  15  to move each gripper  8  from the first end  101  to the second end  102  of the respective cam element  230 . In the illustrated embodiment, the second attachment element is a bracket  16 , which is pierced by an opening  17  for accommodating and end of the operating bolt assembly, which is discussed further below. 
       FIG.  11    shows a perspective view of the push ring  14 . The push ring  14  has an inner surface  112  sized to fit around the pipe  19 , and an outer surface  111  sized to fit within the interior bore  150  of the pocket section  4  of the body  1 . A number of apertures  20  are provided through the push ring  14 , sized to fit the grippers  8  and aligned with the apertures  12  in the pocket section  4  of the body  1 . 
       FIG.  12    shows a perspective view of a gripper  8 . The gripper  8  is configured to extend through the apertures  12  in the pocket section  4 , through the apertures  20  in the push ring  14 , and into the first depth  110  of the cam elements  230 . The gripper  8  has an outer surface  120  that fits within the cam elements  230  of the cam ring  15 , and has an inner end  122  curved to fit around the pipe  19 . The inner end  122  can have teeth  123  to positively grip the pipe  19 . 
       FIGS.  1  and  13    show perspective views of two options for an operating bolt assembly. In  FIG.  1   , the operating bolt  5  is a piece of threaded rod. Nuts  6 ,  11  are threaded onto opposite ends of the bolt  5 , and t-fittings  7 ,  9  are slid onto the bolt  5  inward of the nuts  6 ,  11 . A washer  10  facilitates rotation of the nut  11  over the t-fitting  7 . T-fitting  7  is shaped to engage first bracket  16  on the cam ring, and t-fitting  9  is shaped to engage the bracket  21  on the body  1 . T-fitting  7  can have a first curved surface, and the second bracket  21  can have a second curved surface congruent with the first curved surface such that the first curved surface pivots against the second curved surface as the t-fitting  7  and second bracket  21  are drawn toward the first bracket  16 . Nuts  6 ,  11  form operating elements for the operating bolt  5 , such that when either nut  6 ,  11  is rotated, the t-fittings  7 ,  9  are drawn together against brackets  16 ,  21 , causing cam ring  15  to rotate, as described further below. 
       FIG.  13    shows a variation on the operating bolt. In this variation, threaded rod  5 , nut  11 , t-fitting  9  and washer  10  are replaced by a t-bolt  135  which has a t-shaped section  139  on the end which engages bracket  21 . Nut  6  and t-fitting  7  are threaded onto the opposite end of the t-bolt  135 , and engage bracket  16  on the cam ring  15 . In this variation, the t-shaped section  139  is stationary, and the cam ring  15  is rotated by rotating nut  6 , which forms a single operating element for the operating bolt. 
       FIG.  14    shows a perspective view of a retainer ring  18 . The retainer ring  18  fits in groove  198  to retain the cam ring  15  on the pocket section  4 . As shown in the figure, the retainer ring  18  can be a conventional “c clip”, or any other design known in the art. 
     Assembly of the Pipe Connector 
       FIGS.  15   a  through  19   b    show the steps of assembling the pipe connector  99 . 
     As shown in  FIGS.  15   a - 15   b   , the seal element  13  is inserted into groove  153  inside the inner bore  150  of the pocket section  4  of the body  1 . 
     As shown in  FIGS.  16   a - 16   b   , the push ring  14  is inserted into the inner bore  150  of the pocket section  4 , with the apertures  20  in the push ring  14  aligned with the apertures  12  in the pocket section  4 . 
     As shown in  FIGS.  17   a - 17   b   , the grippers  8  are inserted into cavities  162  formed by the aligned apertures  12  in the pocket section  4  and apertures  20  in the push ring  14 . 
     As shown in  FIGS.  18   a - 18   b   , the cam ring  15  is assembled onto the outer surface  91  of the pocket section  4  of the body  1 . The cam ring  15  is positioned such that the entry sections  231  of the cam surfaces  230  will fit over the grippers  8  in cavities  162 , and such that the first bracket  16  on the cam ring  15  is properly aligned with the second bracket  21  on the body  1  for insertion of the operating bolt  5 , in the step below. 
     As shown in  FIGS.  19   a  and  19   b   , the retaining ring  18  is placed into the groove  198  in the outer surface  91  of pocket section  4 , retaining the cam ring  15  in place. 
     The operating bolt assembly is placed. In the example of  FIGS.  20   a  and  20   b   , the t-bolt  135  is inserted through aperture  22  of the second bracket  21  so that t-shaped section  139  seats against the second bracket  21 . The opposite end of the t-bolt  135  is inserted through aperture  17  in the first bracket  16  of the cam ring  15 . T-fitting  17  is slid onto t-bolt  135  and seated against the first bracket  16 , then nut  6  is threaded onto t-bolt  135 , readying the pipe connector  99  for use. 
     Operation of the Pipe Connector 
       FIGS.  2 - 4  and  21    show the valve  100  with pipe connector  99  in a first position, while  FIGS.  5 - 7    show the valve  100  with the pipe connector  99  in a second position. In the first position, the pipe connector  99  is open for insertion of the pipe  19 , and in the second position the pipe  19  is held in place and fluid-sealed. 
     Referring to  FIG.  21   , which is a cut-through view, in the first position the seal element  13  is around the pipe  19 , but is uncompressed. The grippers  8  are within the cam element  230  at the first end  101 —at first axial location  232  and first depth  110 —which is farthest radially outward within the cam element  230  and farthest from the first axial side  103  of the cam ring  15 . The push ring  14  is similarly in a position that is farthest from the first axial side  103  of the cam ring  15 . 
       FIG.  22   a    shows the valve  100  with a pipe  19  inserted into the pipe connector  99 , and the cam ring  15  in the first position. When nut  6  is rotated around t-bolt  135 , it presses t-fitting  7  against the first bracket  16  and t-fitting  139  against the second bracket  21 , drawing the two brackets  16 ,  21  closer to each other. As shown in  FIG.  22   b   , this operation causes the cam ring  15  to rotate toward the second position. 
       FIG.  23   a    shows a perspective view of the cam ring  15 , a gripper  8 , and the push ring  14  in the first position.  FIGS.  24   a  and  26   a    show end and side cut-through views, respectively. As the cam ring  15  is rotated toward the second position, as shown in  FIGS.  23   b ,  24   b , and  26   b   , the gripper  8  is moved within the cam element  230 , and the shape of the cam element  230  as described above urges the gripper  8  in two directions—axially toward the first axial side  103  of the cam ring  15 , and radially inward toward the pipe  19 . The axial movement of the grippers  8  also exerts an axial force to move the push ring  14  toward the first axial side  103 , which compresses the seal element  13  as shown in  FIG.  25   . This compression of the seal element  13  tightens the seal element  13  around the pipe  19 , to create a fluid-tight seal. With the same operation of the tightening element, the radially-inward movement of the grippers  8  force the teeth  123  of the grippers  8  into the pipe, physically and mechanically holding the pipe  19  in place within the body  1 . The axial shift of the grippers  8  can occur before the radial shift of the grippers  8 , or the full axial shift of the grippers  8  can occur before the full radial shift of the grippers  8 , so that the seal element  13  can be sufficiently compressed before the grippers  8  bite on the pipe  9 , the latter of which would restrict further axial shift of the grippers  8 . Accordingly, when the grippers  8  move from the first ends  101  to the second ends  102  of the cam elements  230 , a majority or all of the shift from the first axial location  232  to the second axial location  234  occurs before the completion of the radial shift from the first depth  110  to the second depth  113  is completed. 
     Further Embodiment(s) of the Pipe Connector 
       FIG.  27    shows an exploded perspective view of a pipe connector  300  according to an embodiment. The pipe connector  300  includes a cam ring  310  and a gripper  370  that are alternative embodiments to the cam ring  15  and gripper  8 . Other features of the pipe connector  300  are the same as the pipe connector  1  unless otherwise discussed. 
       FIG.  28    shows a perspective view of the cam ring  310  and the gripper  370 . The cam ring  310  is similar to the cam ring  15 , but each cam element  314  includes further cam sections each having different degrees of sloping and radial depth. A first cam section  316  has a first radial depth. The gripper  370  is at this first cam section  316  before the pipe  19  is inserted and gripped by the pipe connector  300 . A second cam section  320  adjacent the first cam section  316  has a slope radially inward from the first cam section  316  at a relatively steep angle (relative to the slope of some of the other cam sections) in order to draw the gripper  370  close to the pipe  19  with short or minimal rotation of the cam ring  310 . A third cam section  330  adjacent the second cam section  320  shifts axially from the second cam section  320 , such that as the cam ring  310  rotates and the gripper  370  moves through the third cam section  330 , the gripper  370  is pushed axially to compress the push ring  14  against the seal element  13 . A fourth cam section  340  adjacent the third cam section  330  has a slope radially inward from the third cam section  330  at a shallow angle relative to the slope of other cam sections, such as the second cam section  320 . The slope of the fourth cam section  340 , when the cam ring  310  is rotated, begins wedging the gripper  370  into the pipe  19 . A fifth cam section  350  adjacent the fourth cam section  340  has a slope radially inward from the fourth cam section  340  also at a relatively shallow angle relative to the slope angle of the second cam section  320 . This slope of the fifth cam section  350  is configured to continue wedging the gripper  370  against the pipe  19  when pipe  19  is ductile iron or other similar hardness, compressing the gripper  370  against the ductile pipe to create a frictional force strong enough to hold the ductile pipe. A sixth cam section  360  adjacent the fifth cam section  350  includes a final slope radially inward from the fifth cam section  350  at a steep angle relative to the slope angle of the fifth cam section  350 . This final slope is configured to wedge a plurality of teeth  372  of the gripper  370  into PVC pipe, or other pipe of similar hardness. 
     When the gripper  370  of  FIG.  28    is at the first cam section  316  before a pipe  19  is in and gripped by the pipe connector  300 , so that the pipe  19  can be inserted without interference from the gripper  370 , the gripper  370  can be held at a minimum radially outward position. This minimum radially outward position corresponds with holes  374  in each gripper  370 . The gripper  370  can have a body with a first side, a second side adjacent the first side, a third side adjacent the first side and opposite the second side, and a fourth side adjacent the second side and the third side and opposite the first side. Retention elements  376  made of plastic or other suitably soft but rigid material can be mounted in and extend from the holes  374 , such that if the gripper  370  moves radially inward with light force (e.g., the force of gravity or less), the retention elements  376  then hit the push ring  14 , which prevents further radially inward movement of the gripper  370  and prevents the gripper  370  from obstructing a path for the pipe  19  to be inserted within the pipe connector  300 . After the pipe  19  is inserted into the pipe connector  300 , when the cam ring  310  is rotated to move the gripper  370  axially, the applied force causes the retention elements  376  to rip or sheer off against the push ring  14 , allowing the gripper  370  to continue moving radially inward to grip the pipe  19 . 
       FIG.  29    shows a perspective view of the plurality of gripper teeth  372 . Shown in  FIG.  29   , the plurality of teeth  372  have increasing sharpness moving across the plurality of teeth  372  from one tooth to each adjacent tooth. A first end tooth  378  has a first degree of sharpness that is the dullest of all the teeth  372 . The dull first end tooth  378  facilitates properly orienting the gripper  370  when the gripper  370  begins wedging against the pipe  19 . A first middle tooth  380  is sharper than the first end tooth  378 . A second middle tooth  382  is sharper than the first middle tooth  380 , though it could also be the same sharpness as the first middle tooth  380 . Two middle teeth are shown, though there could be more or less, each with the same sharpness or with increasing sharpness moving from one tooth to an immediately adjacent tooth in a direction away from the first end tooth  378 . A second end tooth  384  has a sharpness greater than the first end tooth  378 , the first middle tooth  380 , and the second middle tooth  382 . The increasing sharpness from each successive tooth facilitates reorientation on an increasingly fine scale, to properly orient the gripper  370  as the gripper teeth  372  gradually and increasingly bite against and/or into the pipe  19 . When the pipe  19  is hard like ductile iron pipe, the teeth  372  flatten against the pipe  19  with increasing force, and when the pipe is softer, as with PVC pipe, the sharper teeth  372  cut into the surface of the pipe  19 . 
     Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.