关键词: 抽油机, 等效动力学模型, 平衡扭矩

Abstract: In this paper,under the conditions of the static load and inertial load of the polished-rod of a conventional pumping unit,as well as the structural weight and inertia,we have presented on equivalent dynamic model of the pumping unit system relative to crank;meanwhile,theaccurate analytical expressions of the amplitudes and phases of the first-order and second-order synchronous waves of the balance torgue have been obtained under equilibrium conditionof overall outer forces,and the type-curves of net torque of the crankshaft with the characteristic of inertial counterbalance have been drawn.