Method and apparatus for controlling a walking beam pump
AssigneeMagneTek, Inc.
InventorsKenneth E. Opal, William J. Happel
Life of this patent
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Abstract
Method for controlling an electric drive motor coupled to a reciprocating mechanical system such as an oil well walking beam pump by inserting a pair of power-off pulses in a reciprocation period of the pump motor energization cycle, with one pulse in a top-of-cycle region and the other pulse in a bottom-of-cycle region to reduce rod stress and motor electrical power consumption and increase pump displacement and efficiency.
Claims10
In a walking beam pump system having an electrical motor coupled through a drive system to pumping apparatus which includes reciprocating pump means operated by a walking beam mounted for cyclical rocking movement, the apparatus including an inertial mass tending to maintain the rocking movement, the method of controlling the pump system comprising the steps of:
- driving the walking beam by the motor during part of the rocking cycle to provide pumping effort;
- turning off the motor when the walking beam approaches the upper limit of its rocking cycle and holding the motor off until the rocking cycle is in a downward movement, and
- turning off the motor when the walking beam approaches the lower limit of its rocking cycle and holding the motor off until the rocking cycle is in an upward movement;
- wherein inertial movement of the pumping apparatus continues the rocking cycle and the motor is driven by the pumping apparatus when it is turned off.
A walking beam pump system including:
- a walking beam mounted for cyclical rocking movement;
- an electrical motor having on and off periods during the rocking cycle for driving the walking beam during on periods;
- driving apparatus for coupling the motor to the walking beam, the driving apparatus having an inertial mass for maintaining rocking movement and driving the motor during motor off periods;
- means for sensing the operating parameters of the pump system;
- and
- motor control means responsive to the operating parameters for establishing the motor on and off periods for improved operation compared to full time motor driving including a first circuit for determining a first off period beginning as the walking beam approaches the upper limit of the rocking cycle, and a second circuit for determining a second off period beginning when the walking beam approaches the lower limit of the rocking cycle, each circuit being effective to turn off the motor for the duration of the respective off period.
Dependencies are inferred from the claim text.