Thesis for the scientific degree of candidate of Technical Science on the speciality 05.02.02 – Machine Science. – National Technical University of Ukraine “Igor Sicorsky Kyiv Polytechnic Institute” of the Ministry of Education of Ukraine, Kyiv, 2021.
The thesis is devoted to the development of an adaptive cross-linked hydraulic system with improved static, energy and dynamic characteristics.
The analysis of works on research topics is carried out. The principle of operation has been substantiated and schemes of variants of an adaptive hydraulic system based on one and two variable pumps have been developed. The hydraulic system uses electro-hydraulic directional valves, a controller and a sensor system. In the developed versions of the adaptive hydraulic system, the controller implements a cross link between the two circuits, which allows matching the speed values of the hydraulic motors, ensuring the smooth operation of the machine and the maximum loading of the pumps by pressure.
It is proposed to form the cross link, which is implemented by the controller, in the form of the sum of the main and corrective components. The correction component is the product of the derivative of the pressure sensor signal and the transmission coefficient. The correcting component is added to the main one with a certain time delay.
Mathematical models of adaptive hydraulic systems based on one and two adjustable pumps have been developed. The mathematical models take into account the moments of inertia of the working mechanisms, the flow characteristics of the directional valve are determined on the basis of modeling the flow of working fluid through the working windows and experimentally determined characteristics of the controller. The influence of hydraulic system operating modes, as well as parameters of regulators and cross link parameters on dynamic characteristics has been studied. It was found that the dynamic characteristics of the adaptive hydraulic system depend on the ratio of the values of the design parameters of the pump regulator and the differential pressure valve. The optimal combinations of parameters of regulators and parameters of cross link are found.
A prototype of a sectional directional valve with proportional electrohydraulic control is designed. The scheme of the adaptive hydraulic system for the mobile working machine of the BAM-2014 type which is issued by the “Budagromash” (Kyiv) enterprise of is developed. The operation of the adaptive hydraulic system with the hydraulic system of the base machine is compared. Power losses on auger drilling operations in the main contour are reduced by (7.7 -13.7) kW, and in the feed contour by (13.3 - 15.6) kW. Requirements are provided for the accuracy of stabilization of the speeds of the working mechanism, for the time of regulation and overshoot. The expected economic effect from the use of the developed adaptive hydraulic system on the mobile working machine type BAM-2014 is 44.880 UAH/year.
Test stand for investigation of the adaptive hydraulic system based on a variable pump, directional control valve with proportional electrohydraulic control and a controller as well as the program for computation of static, dynamic and energy characteristics of the adaptive control system are implemented into the educational process in Vinnytsia National Technical University.
The developed circuit of the adaptive hydraulic system and the sectional directional control valve design can also be used for developing hydraulic drives of other mobile machines, where it is necessary to provide regulation, stabilization and coordination of the speed modes of hydraulic engines, such as drilling-crane machines БКМ-2М, БКМ-3У. The results of the work can also be used at Kharkiv Tractor Plant, Drogobych Truck Crane Plant, Turbiv Machine-Building Plant, Kalynivka Machine-Building Plant.
Key words: adaptive hydraulic system, directional valve, cross link, mobile machine, power loss reduction.
