Stability Assessment of the Movement Velocity for Hydraulic Drive Output Link Under Variable Load Conditions

The question of the stability assessment of the movement velocity for hydraulic drive output link under variable load conditions, in particular, the stability of the movement speed of the hydraulic cylinder piston, is considered. The calculation scheme of hydraulic drive is presented, the nonlinear mathematical model is compiled, which takes into account the main factors that determine the velocity instability, namely, the movement inertia of output link and the compressibility of working fluid in the cavities of the hydraulic cylinder. The quadratic dependence for hydraulic losses, as well as the resistance force proportional to the movement velocity, were taken into consideration. In accordance with the task, the arbitrary law of loading for the working body is considered. The linearization of the mathematical model has been performed, the transfer function for the movement velocity of the hydraulic cylinder piston at the load has been obtained. The expressions for calculating the transfer function coefficients are presented. On the basis of the results obtained, the express method for the stability assessing of the movement velocity of the hydraulic cylinder piston under variable load is proposed. According to the method, it is required to set the number of initial parameters, determine the transfer function for the output link velocity, calculate using known software for the transient process and frequency characteristics. The example of calculating the transient process, amplitude and phase frequency characteristics for the movement velocity for the working body of the power hydraulic drive for technological equipment is presented.