Knowledge of the magnitude of different components of mechanical torque acting on the gearbox is crucial for the design and analysis of sucker-rod pumping installations. Gearbox torques include the torque required to drive the polished rod and the torque used to rotate the counterweights. In addition to these, inertial torques arise in those parts of the pumping unit that turn at varying speeds. As shown in the paper, all torque components are functions of the crank angle, consequently their exact calculation necessitates the knowledge of the crank angle vs. time function. This circumstance, however, complicates torque calculations because contemporary dynamometers, used to acquire the necessary operating data, do not provide any information on the variation of the crank angle during the pumping cycle. The paper introduces a solution of the problem and presents an iterative calculation of the crank angle vs. time function from dynamometer data. Based on this function crank velocity, acceleration, as well as beam acceleration are easily found and all necessary gearbox torques can be evaluated. The paper describes the details of the developed calculation model and presents example calculations.
Presenters
Gabor Takacs, Laszlo Kis and Adam Koncz
University of Miskolc, Hungary