MODELING THE INFLUENCE OF THE COMPRESSIBILITY OF THE WORKING FLUID ON THE EFFICIENCY INDICATORS OF HYDRAULIC ACTUATORS OF WORKING EQUIPMENT OF TECHNOLOGICAL MACHINES

Abstract

The article is devoted to the mathematical modeling of the hydraulic control system of the working equipment of technological machines, using the example of the hydraulic drive of the bulldozer blade, taking into account the influence of the compressibility of the working fluid. The article analyzes current scientific research in the field of increasing the efficiency and performance of power drives of technological machines in order to identify the degree of disclosure of the issue of the influence of variable parameters of the working fluid on the general indicators of the hydraulic drive as a single system. It is determined that the variable characteristics of the working fluid, such as viscosity, bulk modulus, compressibility, which in the vast majority of studies are considered as constant values, although they significantly affect the efficiency indicators of machines. A mathematical model of a hydraulic drive for controlling a bulldozer blade is proposed, which is built using the classical laws of mechanics and hydraulics, but unlike existing models, it takes into account the influence of the compressibility of the working fluid on the kinematics of blade movement, which is useful for assessing the efficiency of bulldozers when operating under different operating conditions of the working fluid. To achieve the goal of the work, a partial solution of the mathematical model was obtained, which establishes the regularity of the influence of the bulk elasticity modulus of the working fluid on the speed of operation of the blade hydraulic cylinders. A numerical analysis of the proposed mathematical model was carried out using the example of the hydraulic drive of the blade of the CAT D9 bulldozer. The regularities of the influence of the compressibility of the working fluid on the speed of movement of the blade hydraulic cylinder rod were obtained, as well as the regularities of the change in the rod movement time depending on the bulk elasticity modulus of the fluid and different values of the rod stroke. The obtained patterns and numerical results allow predicting the efficiency indicators of cyclic technological machines, for example, their productivity by setting the cycle time, at different values of the fluid elasticity modulus, which is useful both at the stage of selecting hydraulic oil and in the operating conditions of changes in the compressibility of the oil over time.