Linear Rod Pump Apparatus and Method

A linear rod pumping apparatus, for imparting reciprocating substantially vertical motion to a rod of a sucker-rod pump having a pump stroke, the apparatus comprising:

• a linear mechanical actuator arrangement, having a substantially vertically movable member attached to the rod of the sucker-rod pump for imparting and controlling vertical motion of the rod of the sucker-rod pump with the linear mechanical actuator arrangement comprising:
• a rack and pinion gearing arrangement, with the rack being disposed for operation in a substantially vertical direction for reciprocating motion;
• the rack being operatively connected in gear mesh relationship with the pinion, and the pinion being operatively connected to the rotating output of the motor, such that rotation of the motor in a first direction is accompanied by a substantially vertically upward motion of the rack, and such that a substantially vertically downward motion of the rack is accompanied by rotation of the motor rotatable element in a second direction opposite the first direction;
• the rack also being operatively connected to the rod of the sucker-rod pump for imparting vertically upward motion to the rod of the sucker-rod pump along the pumping axis when the rack is moving downward;
• and
• the rack further being operatively connected to the rod of the sucker-rod pump such that the rod of the sucker-rod pump exerts a substantially vertically upward directed force on the rack, during a portion of the pump stroke.
• a pulley operatively associated with the linear mechanical actuator;
• a cable which is operatively connected to both the rack and the rod of the sucker-rod pump, wherein the cable passes over the pulley;
• and
• a reversible motor having a reversibly rotatable element thereof operatively connected to the substantially vertically movable member of the linear mechanical actuator arrangement in a manner establishing a fixed relationship between the rotational position of the motor and the vertical movement of the vertically movable member.