Coupling Having Gasket Pocket of Varying Depth

Abstract

A mechanical coupling for joining pipe elements has segments joined end to end, each segment having a pocket of varying depth for receiving a ring gasket. The varying depth of the pocket is used to control the distortion of the ring gasket between a round shape and a non-round shape when the segments are arranged in spaced apart relation around the ring gasket, the spacing between the segments being sufficient to permit insertion of the pipe elements without disassembly of the coupling.

What is claimed is: 
     
         1 . A coupling for joining pipe elements in end to end relation, said coupling comprising:
 a plurality of segments joined end to end surrounding a central axis and defining a central space for receiving said pipe elements, at least one of said segments comprising:   a pair of projections positioned in spaced apart relation on opposite sides of said one segment and extending toward said central axis, at least a portion of each of said projections being engageable with a respective one of said pipe elements, at least one of said projections having an arcuate surface facing said central axis;   a back wall extending between said projections, said back wall having a surface facing said central axis, said surface of said back wall comprising a first surface portion having a first radius of curvature, and a second surface portion having a second radius of curvature, said second surface portion being positioned proximate to one end of said at least one segment, any point on said second surface portion being farther from said central axis than any point on said first surface portion, a distance between said surface of said back wall and said arcuate surface of said at least one projection, as measured along a radially projecting line extending from said central axis, being a first value at a first point midway between said ends of said at least one segment, and a second value at a second point proximate to said one end of said at least one segment, said first value being less than said second value; and   a ring gasket positioned within said central space, said ring gasket having an outer circumference having a length greater than the sum of the lengths of said surfaces of said back walls of said segments, said ring gasket supporting at least two of said segments in spaced apart relation.   
     
     
         2 . The coupling according to  claim 1 , wherein said distance is a minimum at said first point midway between said ends of said at least one segment. 
     
     
         3 . The coupling according to  claim 2 , wherein said distance is a maximum at said second point, said second point being positioned at said one end of said at least one segment. 
     
     
         4 . The coupling according to  claim 3 , wherein said distance between said surface of said back wall and said arcuate surface of said at least one projection at a third point positioned at another of said ends of said at least one segment is a third value equal to said second value. 
     
     
         5 . The coupling according to  claim 4 , wherein said surface of said back wall further comprises a third surface portion having a third radius of curvature, said third surface portion being positioned proximate to said another of said ends of said at least one segment, any point on said third surface portion being farther from said central axis than any point on said first surface portion. 
     
     
         6 . The coupling according to  claim 4 , wherein said second surface portion subtends an angle from about 5° to about 80°. 
     
     
         7 . The coupling according to  claim 4 , wherein said second surface portion subtends an angle from about 5° to about 45°. 
     
     
         8 . The coupling according to  claim 5 , wherein said third surface portion subtends an angle from about 5° to about 80°. 
     
     
         9 . The coupling according to  claim 5 , wherein said third surface portion subtends an angle from about 5° to about 45°. 
     
     
         10 . The coupling according to  claim 1 , comprising only a first and a second of said segments joined end to end surrounding said central axis. 
     
     
         11 . The coupling according to  claim 10 , wherein said ring gasket has an oval shape. 
     
     
         12 . The coupling according to  claim 10 , wherein said ring gasket has a round shape. 
     
     
         13 . A coupling for joining pipe elements in end to end relation, said coupling comprising:
 a plurality of segments joined end to end surrounding a central axis and defining a central space for receiving said pipe elements, at least one of said segments comprising:   a pair of projections positioned in spaced apart relation on opposite sides of said one segment and extending toward said central axis, at least a portion of each of said projections being engageable with a respective one of said pipe elements, at least one of said projections having an arcuate surface facing said central axis;   a back wall extending between said projections, said back wall having a surface facing said central axis, said surface of said back wall comprising a first surface portion having a first radius of curvature, and a second surface portion having an infinite radius of curvature, said second surface portion being positioned proximate to one end of said at least one segment, any point on said second surface portion being farther from said central axis than any point on said first surface portion, a distance between said surface of said back wall and said arcuate surface of said at least one projection, as measured along a radially projecting line extending from said central axis, being a first value at a first point midway between said ends of said at least one segment, and a second value at a second point proximate to said one end of said at least one segment, said first value being less than said second value; and   a ring gasket positioned within said central space, said ring gasket having an outer circumference having a length greater than the sum of the lengths of said surfaces of said back walls of said segments, said ring gasket supporting at least two of said segments in spaced apart relation.   
     
     
         14 . The coupling according to  claim 13 , wherein said distance between said surface of said back wall and said arcuate surface of said at least one projection at a third point positioned proximate another of said ends of said at least one segment is a third value equal to said second value. 
     
     
         15 . The coupling according to  claim 14 , wherein said surface of said back wall further comprises a third surface portion having an infinite radius of curvature, said third surface portion being positioned proximate to said another of said ends of said at least one segment. 
     
     
         16 . The coupling according to  claim 13 , wherein said second surface portion subtends an angle from about 5° to about 45°. 
     
     
         17 . The coupling according to  claim 13 , wherein said second surface portion subtends an angle from about 5° to about 30°. 
     
     
         18 . The coupling according to  claim 15 , wherein said third surface portion subtends an angle from about 5° to about 45°. 
     
     
         19 . The coupling according to  claim 15 , wherein said third surface portion subtends an angle from about 5° to about 30°. 
     
     
         20 . The coupling according to  claim 13 , further comprising a plurality of said second surface portions, each of said second portions having infinite radii of curvature. 
     
     
         21 . The coupling according to  claim 20 , wherein said surface of said back wall further comprises a plurality of third surface portions each having an infinite radius of curvature, said third surface portions being positioned proximate to another of said ends of said at least one segment. 
     
     
         22 . The coupling according to  claim 20 , wherein said plurality of said second surface portions subtends an angle from about 5° to about 45°. 
     
     
         23 . The coupling according to  claim 20 , wherein said plurality of said second surface portions subtends an angle from about 5° to about 30°. 
     
     
         24 . The coupling according to  claim 21 , wherein said plurality of said third surface portions subtends an angle from about 5° to about 45°. 
     
     
         25 . The coupling according to  claim 21 , wherein said plurality of said third surface portions subtends an angle from about 5° to about 30°. 
     
     
         26 . The coupling according to  claim 13 , comprising only a first and a second of said segments joined end to end surrounding said central axis. 
     
     
         27 . The coupling according to  claim 26 , wherein said ring gasket has an oval shape. 
     
     
         28 . The coupling according to  claim 26 , wherein said ring gasket has a round shape. 
     
     
         29 . A coupling for joining pipe elements in end to end relation, said coupling comprising:
 a plurality of segments joined end to end surrounding a central axis and defining a central space for receiving said pipe elements, at least one of said segments comprising:   a pair of projections positioned in spaced apart relation on opposite sides of said one segment and extending toward said central axis, at least a portion of each of said projections being engageable with a respective one of said pipe elements, each of said projections having an arcuate surface facing said central axis, said arcuate surface having a first radius of curvature measured from a first center of curvature;   a back wall extending between said projections, said back wall having an arcuate surface facing said central axis, said arcuate surface of said back wall having a second radius of curvature measured from a second center of curvature, said second center of curvature being non-coincident with said first center of curvature as measured in a plane perpendicular to said central axis.   
     
     
         30 . The coupling according to  claim 29 , wherein said first center of curvature is closer to said arcuate surface of said back wall than said second center of curvature when measured to a point on said arcuate surface of said back wall that is collinear with said first and second centers of curvature. 
     
     
         31 . The coupling according to  claim 30 , wherein said first and second centers of curvature and said point on said back wall are collinear along a first line oriented perpendicular to a second line extending between a first end of said one segment and a second end of said one segment. 
     
     
         32 . The coupling according to  claim 31 , wherein said second center of curvature is offset from said first center of curvature at a distance from about 0.01 inches to about 0.1 inches. 
     
     
         33 . The coupling according to  claim 31 , wherein said second center of curvature is offset from said first center of curvature at a distance of about 0.02 inches to about 0.04 inches. 
     
     
         34 . The coupling according to  claim 31 , wherein said second center of curvature is offset from said first center of curvature at a distance of about 0.03 inches. 
     
     
         35 . The coupling according to  claim 31 , comprising only a first and a second of said segments joined end to end surrounding said central axis, said coupling further comprising a ring gasket positioned between said first and second segments, said ring gasket having an outer circumference having a length greater than the sum of the lengths of said arcuate surfaces of said back walls of said first and second segments, said ring gasket supporting said first and second segments in spaced apart relation. 
     
     
         36 . The coupling according to  claim 35 , wherein said ring gasket has an oval shape. 
     
     
         37 . The coupling according to  claim 35 , wherein said ring gasket has a round shape. 
     
     
         38 . A coupling for joining pipe elements in end to end relation, said coupling comprising:
 first and second segments joined end to end surrounding a central axis and defining a central space for receiving said pipe elements, each one of said segments comprising:   first and second projections, each positioned in spaced apart relation on opposite sides of said segment and extending toward said central axis, at least a portion of each of said projections being engageable with a respective one of said pipe elements, each said projection having an arcuate surface facing said central axis, each said arcuate surface having a first radius of curvature measured from a first center of curvature;   a back wall extending between said first and second projections, said back wall having an arcuate surface facing said central axis, said arcuate surface of said back wall having a second radius of curvature measured from a second center of curvature, said second center of curvature being non-coincident with said first centers of curvature as measured in a plane perpendicular to said central axis.   
     
     
         39 . The coupling according to  claim 38 , wherein, for each of said projections on each of said segments as measured in said plane, said first center of curvature is closer to said arcuate surface of said back wall than said second center of curvature when measured to a point on said arcuate surface of said back wall that is collinear with said first and second centers of curvature. 
     
     
         40 . The coupling according to  claim 39 , wherein, for said first segment and for each of said projections thereon, said first and second centers of curvature and said point on said back wall are collinear along a first line oriented perpendicular to a second line extending between a first end of said first segment and a second end of said first segment. 
     
     
         41 . The coupling according to  claim 40 , wherein, for said second segment and for each of said projections thereon, said first and second centers of curvature and said point on said back wall are collinear along a first line oriented perpendicular to a second line extending between a first end of said second segment and a second end of said second segment. 
     
     
         42 . The coupling according to  claim 41 , wherein, for each of said projections on each of said segments, said second center of curvature is offset from said first center of curvature at a distance from about 0.01 inches to about 0.1 inches. 
     
     
         43 . The coupling according to  claim 41 , wherein, for each of said projections on each of said segments, said second center of curvature is offset from said first center of curvature at a distance of about 0.02 inches to about 0.04 inches. 
     
     
         44 . The coupling according to  claim 41 , wherein, for each of said projections on each of said segments, said second center of curvature is offset from said first center of curvature at a distance of about 0.03 inches. 
     
     
         45 . The coupling according to  claim 41  further comprising a ring gasket positioned between said first and second segments, said ring gasket supporting said first and second segments in spaced apart relation sufficient to insert said pipe elements between said segments. 
     
     
         46 . The coupling according to  claim 45 , wherein said ring gasket has an oval shape. 
     
     
         47 . The coupling according to  claim 45 , wherein said ring gasket has a round shape. 
     
     
         48 . A coupling for joining pipe elements in end to end relation, said coupling comprising:
 first and second segments joined end to end surrounding a central axis and defining a central space for receiving said pipe elements, each one of said segments comprising:   first and second projections, each positioned in spaced apart relation on opposite sides of said segments and extending toward said central axis, at least a portion of each of said projections being engageable with a respective one of said pipe elements, each of said projections having an arcuate surface facing said central axis;   a back wall extending between said first and second projections, said back wall having an arcuate surface facing said central axis, a distance between said arcuate surface of said back wall and said arcuate surfaces of said projections, as measured along a radially projecting line extending from said central axis, being a first value at a point midway between said ends of said segments, and a second value at a point proximate to one end of each of said segments, and a third value at a point proximate to an opposite end of each of said segments, said first value being less than said second value and said third value; and   a ring gasket positioned within said central space, said ring gasket having an outer circumference having a length greater than the sum of the lengths of said arcuate surfaces of said back walls of said first and second segments, said ring gasket supporting said first and second segments in spaced apart relation.   
     
     
         49 . The coupling according to  claim 48 , wherein said distance is a minimum at said first point midway between said ends of said at least one segment. 
     
     
         50 . The coupling according to  claim 49 , wherein said distance is a maximum at said second point, said second point being positioned at said at least one end of said at least one segment. 
     
     
         51 . The coupling according to  claim 50 , wherein said distance between said arcuate surface of said back wall and said arcuate surface of said at least one projection at a third point positioned at another of said ends of said at least one segment is a third value approximately equal to said second value. 
     
     
         52 . The coupling according to  claim 48 , wherein said arcuate surface of said back wall comprises a first portion having a curved surface, and a second portion having a curved surface, said second portion being positioned proximate to said at least one end of said at least one segment, any point on said second portion being farther from said central axis than any point on said first portion. 
     
     
         53 . The coupling according to  claim 52 , wherein said arcuate surface of said back wall further comprises a third portion having a curved surface, said third portion being positioned proximate to another of said ends of said at least one segment, any point on said third portion being farther from said central axis than any point on said first portion. 
     
     
         54 . The coupling according to  claim 52 , wherein said second portion of said arcuate surface of said back wall subtends an angle from about 5° to about 80°. 
     
     
         55 . The coupling according to  claim 52 , wherein said second portion of said arcuate surface of said back wall subtends an angle from about 5° to about 45°. 
     
     
         56 . The coupling according to  claim 53 , wherein said third portion of said arcuate surface of said back wall subtends an angle from about 5° to about 80°. 
     
     
         57 . The coupling according to  claim 53 , wherein said second portion of said arcuate surface of said back wall subtends an angle from about 5° to about 45°. 
     
     
         58 . The coupling according to  claim 48 , wherein said arcuate surface of said back wall comprises a first portion having a first radius of curvature, and a second portion having an infinite radius of curvature, said second portion being positioned proximate to said at least one end of said at least one segment, any point on said second portion being farther from said central axis than any point on said first portion. 
     
     
         59 . The coupling according to  claim 58 , wherein said arcuate surface of said back wall further comprises a third portion having an infinite radius of curvature, said third portion being positioned proximate to another of said ends of said at least one segment. 
     
     
         60 . The coupling according to  claim 58 , wherein said second portion of said arcuate surface of said back wall subtends an angle from about 5° to about 45°. 
     
     
         61 . The coupling according to  claim 58 , wherein said second portion of said arcuate surface of said back wall subtends an angle from about 5° to about 30°. 
     
     
         62 . The coupling according to  claim 59 , wherein said third portion of said arcuate surface of said back wall subtends an angle from about 5° to about 45°. 
     
     
         63 . The coupling according to  claim 59 , wherein said second portion of said arcuate surface of said back wall subtends an angle from about 5° to about 30°. 
     
     
         64 . The coupling according to  claim 58 , further comprising a plurality of said second portions of said arcuate surface of said back wall, each of said second portions having infinite radii of curvature. 
     
     
         65 . The coupling according to  claim 64 , wherein said arcuate surface of said back wall further comprises a plurality of third portions each having an infinite radius of curvature, said third portions of said arcuate surfaces of said back wall being positioned proximate to another of said ends of said at least one segment. 
     
     
         66 . The coupling according to  claim 64 , wherein said plurality of second portions of said arcuate surface of said back wall subtends an angle from about 5° to about 80°. 
     
     
         67 . The coupling according to  claim 64 , wherein said plurality of second portions of said arcuate surface of said back wall subtends an angle from about 5° to about 30°. 
     
     
         68 . The coupling according to  claim 65 , wherein said plurality of third portions of said arcuate surface of said back wall subtends an angle from about 5° to about 80°. 
     
     
         69 . The coupling according to  claim 65 , wherein said plurality of third portions of said arcuate surface of said back wall subtends an angle from about 5° to about 30°. 
     
     
         70 . The coupling according to  claim 48 , comprising only a first and a second of said segments joined end to end surrounding said central axis. 
     
     
         71 . The coupling according to  claim 70 , wherein said ring gasket has an oval shape. 
     
     
         72 . The coupling according to  claim 70 , wherein said ring gasket has a round shape.