Fiberglass sucker rod end fitting

A sucker rod end fitting comprising:

• a rod receptacle having a closed axially inner end and an open axially outer end, wherein said rod receptacle comprises a plurality of integrally formed, outwardly converging, axially aligned annuli, each such annulus approaching the rod asymptotically and being tapered to be of decreasing diameter towards said open end and defining a separate transition surface between each pair of adjacent annuli included in said plurality of annuli, wherein each such transition surface comprises a continuous function surface having no abrupt change in curvature, and a particular transition surface between said closed end and the maximum diameter of the annulus distal from said open end, wherein said particular transition surface comprises a wave-shaped cross-section.

A sucker rod end fitting comprising:

• an end fitting, said end fitting comprising a rod receptacle to receive said sucker rod to define an internal surface having a closed axially inner end and an open axially outer end, wherein said rod receptacle comprises a plurality of integrally formed, outwardly converging, axially aligned annuli, each such annulus approaching the rod asymptotically and being tapered to be of decreasing diameter towards said open end and defining a separate transition surface between each pair of adjacent annuli included in said plurality of annuli, wherein each such transition surface comprises a continuous function surface having no abrupt change in curvature, and a particular transition surface between said closed end and the maximum diameter of the annulus distal front said open end, wherein said particular transition surface comprises a wave-shaped cross-section;
• and
• a body of initially flowable adhesive that cures to bond said outer surface of said end of said rod and to solidify to form a plurality of wedges to cooperate with said annuli.

A sucker rod string for use in an oil well, said string comprising a plurality of sucker rods connected end to end by end fittings, wherein at least one of said end fittings comprises a rod receptacle to receive a sucker rod and formed to define an internal surface having a closed axially inner end and an open axially outer end, wherein said rod receptacle comprises a plurality of integrally formed, outwardly converging, axially aligned annuli, each such annulus approaching the rod asymptotically and being tapered to be of decreasing diameter towards said open end and defining a separate transition surface between each pair of adjacent annuli included in said plurality of annuli, wherein each such transition surface comprises a continuous function surface having no abrupt change in curvature, and a particular transition surface between said closed end and the maximum diameter of the annulus distal from said open end, wherein said particular transition surface comprises a wave-shaped cross-section.

A sucker rod end fitting comprising:

• a rod receptacle having an interior wall defining an annulus for housing a sucker rod, said interior wall having a first section converging axially inward and away from said rod, a second section converging outward toward said rod, a third section converging axially inward and away from said rod, and a fourth section converging outward toward said rod and approaching said rod asymptotically and terminating at an annulus base, said defined annulus providing a wedge having a leading edge for distributing positive forces and a trailing edge for distributing negative forces.

A sucker rod string for use in an oil well, said string comprising a plurality of sucker rods connected end to end by end fittings, wherein at least one of said end fittings comprises a rod receptacle having an interior wall defining an annulus for housing a sucker rod, said interior wall having a first section converging axially inward and away from said rod, a second section converging outward toward said rod, a third section converging axially inward and away from said rod, and a fourth section converging outward toward said rod and approaching said rod asymptotically and terminating at an annulus base, said defined annulus providing a wedge having a leading edge for distributing positive forces and a trailing edge for distributing negative forces.

A sucker rod end fitting comprising:

• a rod receptacle having an interior wall defining a plurality of axially aligned annuli for housing a sucker rod, wherein each annulus comprises a first section of said interior wall converging axially inward and away from said rod, a second section of said interior wall converging outward toward said rod, a third section of said interior wall converging axially inward and away from said rod, and a fourth section of said interior wall converging outward toward said rod and approaching said rod asymptotically;
• and wherein said fourth section terminates at an annulus base, each said defined annulus providing a wedge having a leading edge for distributing positive forces and a trailing edge for distributing negative forces.

A sucker rod string for use in an oil well, said string comprising a plurality of sucker rods connected end to end by end fittings, wherein at least one of said end fittings comprises a rod receptacle having an interior wall defining a plurality of axially aligned annuli for housing a sucker rod, wherein each annulus comprises a first section of said interior wall converging axially inward and away from said rod, a second section of said interior wall converging outward toward said rod, a third section of said interior wall converging axially inward and away from said rod, and a fourth section of said interior wall converging outward toward said rod and approaching said rod asymptotically;

• and wherein said fourth section terminates at an annulus base, each said defined annulus providing a wedge having a leading edge for distributing positive forces and a trailing edge for distributing negative forces.

A sucker rod end fitting comprising:

• a rod receptacle having an interior wall defining an annulus for housing a sucker rod, said interior wall having a first section converging axially inward and away from said rod, and a second section converging outward toward said rod, said defined annulus approaching the rod asymptotically and providing a wedge having a leading edge for distributing positive forces and a trailing edge for distributing negative forces.

A sucker rod end fitting comprising:

• a rod receptacle having an interior wall defining an annulus for housing a sucker rod, said interior wall having a first section converging axially inward and away from said rod, a second section converging outward for a given distance toward said rod at a given angle, a third section converging axially inward and away from said rod, and a fourth section converging outward for a distance less than said given distance toward said rod and approaching said rod at an angle larger than said given angle, said defined annulus providing a pair of wedges, each having a leading edge for distributing positive forces and a trailing edge for distributing negative forces.