Linearly actuated, pivoting, pumping unit

Abstract

A drive system for stroking a sucker rod that includes a support base; a walking beam; and a linear actuator adapted to expand and retract in length, where an upper bearing couples the upper end of the linear actuator to the walking beam and a lower bearing couples the lower end of the linear actuator to the support base so that the linear actuator can pivot with respect to both the walking beam and the support base as the linear actuator expands and retracts

What is claimed: 
     
         1 . A drive system for stroking a sucker rod, the drive system comprising:
 a support base;   a walking beam;   a linear actuator having a lower end and an upper end, the linear actuator being adapted to expand and retract in length;   an upper bearing coupling the upper end of the linear actuator to the walking beam, such that the actuator can pivot with respect to the walking beam as the linear actuator expands and retracts in length; and   a lower bearing coupling the lower end of the linear actuator to the support base, such that the linear actuator can pivot with respect to the support base as the linear actuator expands and retracts in length.   
     
     
         2 . The drive system of  claim 1  further comprising an electric motor coupled to the lower end of the linear actuator. 
     
     
         3 . The drive system of  claim 2  wherein the support base comprises an internal open space and wherein at least part of the electric motor extends into the internal open space, such that such part of the electric motor can move within the open space as the linear actuator pivots with respect to the support base. 
     
     
         4 . The drive system of  claim 3  wherein the lower bearing comprises first and second lower bearing assemblies, each bearing assembly defining a pivot point about which the linear actuator can pivot with respect to the support base. 
     
     
         5 . The drive system of  claim 4  wherein each of the first and second lower bearing assemblies takes the form of a graphite impregnated bronze bushing. 
     
     
         6 . The drive system of  claim 4  wherein at least part of the electric motor extends above the pivot point and at least part of the electric motor extends below the pivot point. 
     
     
         7 . The system of  claim 1  wherein the upper bearing couples the linear actuator to the walking beam via a bearing saddle coupled to the walking beam. 
     
     
         8 . A drive system for stroking a sucker rod coupled to a sucker rod pump, the drive system comprising:
 a support base;   a Samson post assembly extending upwardly from the support base   a walking beam having a first end and a second end;   a horse head coupled to the first end of the walking beam;   a linear actuator having a lower end and an upper end, the linear actuator being adapted to expand and retract in length;   an upper bearing coupling the upper end of the linear actuator to the walking beam, such that the actuator can pivot with respect to the walking beam as the linear actuator expands and retracts in length;   a lower bearing coupling the lower end of the linear actuator to the support base, such that the linear actuator can pivot with respect to the support base as the linear actuator expands and retracts in length; and   a pivot bearing coupling the second end of the walking beam to the Samson post assembly, such that the walking beam assembly can pivot with respect to the Samson post assembly as the linear actuator expands and retracts in length.   
     
     
         9 . The drive system of  claim 1  wherein the walking beam assembly has a generally “T” shape. 
     
     
         10 . The drive system of  claim 1  further comprising a first hard stop, wherein the first hard stop acts as a barrier limiting the ability of the linear actuator to pivot, relative to the support base, in a first direction. 
     
     
         11 . The drive system of  claim 3  further comprising a second hard stop, wherein the second hard stop acts as a barrier limiting the ability of the linear actuator to pivot, relative to the support base, in a second direction, and wherein the second direction is opposite the first direction. 
     
     
         12 . The drive system of  claim 4  wherein the first hard stop is a cross member positioned in a fixed relationship to the support base. 
     
     
         13 . The drive system of  claim 5  wherein the second hard stop comprises a linkage having a first linkage end and a second linkage end, wherein the first linkage end is pivotably coupled to the cross member and wherein the second linkage end is pivotable coupled to the linear actuator at a point between the upper end of the linear actuator and the lower end of the linear actuator. 
     
     
         14 . The drive system of  claim 13  further comprising first and second Samson post braces extending from the Samson post assembly, wherein the cross member is positioned between the first and second Samson post braces. 
     
     
         15 . A drive system for stroking a sucker rod coupled to a sucker rod pump, the drive system comprising:
 a walking beam having a longitudinal length, a first end, and a second end;   a horse head coupled to the first end of the walking beam;   a support base, the support base comprising a first horizontal section extending in a direction substantially perpendicular to the longitudinal length of the walking beam and a second horizontal section extending substantially parallel to the first horizontal section;   a walking beam bearing assembly coupled to the second end of the walking beam;   first and second support posts, each extending vertically from the second horizontal section of the support base and coupled to the walking beam bearing assembly, such that the walking beam can pivot with respect to the first and second support posts;   first and second support braces, each such support brace extending from one of the first or second support posts to the support base;   a pneumatically balanced linear actuator having a lower end and an upper end, the linear actuator being adapted to expand and retract in length and positioned, in a first direction, between the first and second horizontal sections of the support base and, in a second direction perpendicular to the first direction, between the first and second support braces;
 wherein the upper end of the linear actuator is coupled to the walking beam via an upper actuator bearing, such that the actuator can pivot with respect to the walking beam assembly as the linear actuator expands and retracts in length; and 
 wherein the lower end of the linear actuator is coupled to the support base via a lower actuator bearing, such that the linear actuator can pivot with respect to the support base as the linear actuator expands and contracts in length. 
   
     
     
         16 . The drive system of  claim 15  wherein the first and second support braces are coupled to the first horizontal section of the support base and the lower actuator bearing is located closer to the first horizontal section of the support base than to the second horizontal section of the support base. 
     
     
         17 . The drive system of  claim 15  further wherein the support base further comprises: (i) a third horizontal section extending in a direction substantially parallel to the longitudinal length of the walking beam and between the first and second horizontal sections of the support base and (ii) a fourth horizontal section extending in a direction substantially parallel to the longitudinal length of the walking beam and between the first and second horizontal sections of the support base and wherein the first, second, and third horizontal sections of the support base define an interior square region. 
     
     
         18 . The drive system of  claim 17  wherein the interior square region defines, at least in part, an interior open space and wherein at least a portion of the pneumatically balanced linear actuator is positioned above the interior open space. 
     
     
         19 . The drive system of  claim 18  further comprising a compressor coupled to provide compressed air to the pneumatically balanced linear actuator and wherein the compressor is positioned outside the interior square region. 
     
     
         20 . The drive system of  claim 18  wherein the first and second support braces extend from the first horizontal section of the support base.