Dynamic Analysis On Beam Pumping Unit Considering Firition

Beam pumping unit has been widely used in oil field because of its simple structure, high reliability. By means of knowing the kinematics and dynamics properties of beam pumping unit, we can develop equipment potential and improve their performance. In this dissertation, the steady movement of crank, rotation pair's counterforces and the driving moment of crank of the beam pumping unit are thoroughly studied with considering the friction force and the measured suspension center loading. The main contents are as follows:The kinematics analysis for the mechanism of beam pumping unit is accomplished, the displacement, velocity, acceleration of each component of the beam pumping unit are obtained.According to the principle of equal energy and equal power, the equivalent mechanical model of beam pumping unit considering the pair's friction force is established. The system's nonlinear motion equation is deduced, and the steady movement of crank which is close to the actual moment is obtained by a iterative method for solving the established nonlinear equations.According to the D'Alembert's principle of particle system, the dynamic force and moment balancing equations considering pair's friction force for each component are deduced, and then all the components balancing equations are assembled into the system dynamic equation of the bema pumping unit. A method for solving the equations efficiently is provided. The solutions to the rotation pair's counterforce and the driving moment acting on the crank are obtained by using the presented method.Three kinds of friction model, the Coulomb friction model, combined Coulomb and tanh friction model, and combined Coulomb and tanh friction model considering Stribeck effect, are analyzed. The mechanical efficiency of the beam pumping unit is calculated using above friction models. The results provide reference for designing and improving the properties of this machine.