No abstract

Hydraulic systems based on adjustable pumps, proportional electrohydraulic equipment and controllers are used in mobile machines. The authors propose a new scheme of the hydraulic system for mobile machines, which provides the auger drilling operation. A number of studies have shown that a certain ratio should be maintained between the frequency of auger rotation and its feed during operation, where the productivity of soil disruption should not exceed the productivity of transporting loose soil from the drilling zone. Ensuring the required ratio between the speed of the auger rotation and its feed is implemented by a controller that works according to a certain algorithm. A nonlinear mathematical model of the hydraulic system was developed to create the algorithm for controller operation and setting. The equations of the mathematical model are solved in the MATLAB-Simulink environment by the Rosenbrock method. As a result of solving the equations for the mathematical model, the dependences of variables describing the state of the hydraulic system on time are obtained. The values of the controller settings are determined at which the hydraulic system works steadily, the error of flow rate stabilization, the time for pressure adjustment and readjustment does not exceed the allowable values. The algorithm for controlling the auger feed value is formed. This algorithm provides the necessary ratio between the auger feed and speed, as well as reducing the feed rate in the case of soil hardness increases. This creates the conditions for uninterrupted pit drilling at full depth and protection of the hydraulic system from overload.

Пилявець Володимир Георгійович-аспірант кафедри технології та автоматизації машинобудування. Товкач Артем Олегович-інженер кафедри технологій та автоматизації машинобудування.

Mobile machine hydraulic circuits tend to adopt electrohydraulics. Such hydraulic circuits are based on controlled pumps, modulated hydraulics, sensors and controllers. This allows adapting the hydraulic circuit operating modes to the changes of external conditions of the machine operation. Application of hydraulic circuits with electrohydraulics in mobile machines allows to use mobile machines efficiently with a high number of removable endangers, increases their performance and improves the quality of performed works. The authors propose an adaptive hydraulic circuit for a mobile machine. The operation process in the adaptive hydraulic circuit in static and dynamic modes is determined by the interaction of the pump controller and pressure differential control valves. The hydraulic system operation stability, its fast response and readjustment are determined by the controller parameters. It has been revealed that the main parameters affecting the dynamic characteristics of the hydraulic system are: throttle area and coefficient of amplifying the pump controller orifice, dampener area and coefficient of amplifying the pressure differential control valve orifice. These parameters affect the stability, controlling and readjustment time in the hydraulic circuit differently. A functional including the values of controlling time , σ controlling and losses in the pump controller was used as an optimization criterion. The optimization has been made according to the developed mathematical model applying the method developed by I. Sobol and R. Statnikov. During the optimization each controller parameter changed on 3 levels. 81 tests were made and the best combination of controller parameters for the optimization criterion was determined. The following hydraulic circuit operation values were reached under the optimal values of parameters = 1.0·10-6 m2, = 1.0·10-3 m, = 1.2·10-6 m2, = 10·10-3 m: = 1.1 с, σ = 32 %, = 0.82 kW that comply with the requirements towards hydraulic circuits of mobile machines.

Stable trend of the development of the hydraulic systems of mobile operation machines is the transition to the application of the regulated pumps and hydraulic devices with the proportional electric hydraulic control. In such hydraulic systems the correspondence of pumps capacity to the flow volume, consumed by the hydraulic motors as well as proportionality of the pressure value in the hydraulic system to the loading on the hydraulic motor or the most loaded of the several hydraulic motors is provided.Mobile machines equipped with such hydraulic systems can efficiently operate with wide range of the changeable working tools, providing high quality of the work and loading of the machines during a year. Besides, the proportional control in the hydraulic systems of this type provides high accuracy of the operation execution and greatly improves the working conditions of the operators.The paper considers the adaptive hydraulic system on the base of the distribution valve with proportional electrohydraulic control. Experimental stand for testing the adaptive hydraulic system was constructed. The hydraulic diagram of the distribution valve and the construction of the operation unit is presented. The distribution valve provides the possibility of the remote proportional electromagnetic control of the flow from the controller with the possibility of the stabilization of the hydraulic motors motion speed. Adaptive hydraulic system provides the possibility of the coordination of the hydraulic motors motion speed. The metrologic characteristic of the stand is given , which enables to control the value of the pressure in the hydraulic system, current and voltage values in the control lines, number of rotations of the hydraulic motor and registrate the dependences of the pressure values in the hydraulic system on the time if load changes. It was determined that the error of the flow value stabilization across the distribution valve does not exceed 6.8 %, in the studied range of the load change and the value of the flow changes proportionally according to the signal, sent from the controller. Regulation time in the hydraulic system on the base of the developed distribution valve did not exceed 0.83 sec in the range of the pressure change = (1.5 … 7.0) МPа and the output of the pump = (0.05 … 0.5) • 10 −3 m 3 /sec.