Open AccessAnalysis of the Throttle Speed Control Efficiency in Volumetric Hydraulic Drives
Author(s) -
К. Д. Ефремова,
В. Н. Пильгунов
Publication year - 2019
Publication title -
mašinostroenie i kompʹûternye tehnologii
Language(s) - English
Resource type - Journals
ISSN - 2587-9278
DOI - 10.24108/0219.0001455
Subject(s) - throttle , bandwidth throttling , hydraulic motor , hydraulic fluid , hydraulic pump , automotive engineering , hydraulic cylinder , hydraulic machinery , excavator , hydraulic circuit , engineering , control theory (sociology) , computer science , mechanical engineering , control (management) , gas compressor , artificial intelligence
To control a movement speed of the output link of an executive hydraulic engine (hydraulic cylinder or hydraulic motor), volumetric hydraulic drives traditionally use volumetric and throttle control methods. Under volumetric control, a supply unit employs a pressure-regulated positive displacement pump, as a result of which it is impossible or difficult to separate and independently control the movement speed of the output links of the hydraulic cylinders. In case of throttle control, there is a significant dependence of the speed of the output link on the load it overcomes, a low efficiency of the hydraulic drive and hereto related active heating of the working fluid, as well as large energy losses. However, in embodiment, due to lack of an expensive variable pump, this method of control is much cheaper and can be used in a multi-channel hydraulic drive with a centralized supply unit. Depending on the throttling device localization in the hydraulic drive circuit, there are series (primary or secondary control) and parallel (working fluid bypass adjustment) throttle connection schemes. The secondary control scheme, which generates a pressure in the outlet of the executive hydraulic engine, is preferable due to the fact that it provides an increased pressure in both cavities of the executive hydraulic engine and, accordingly, a lack of combined air bubbles in the working fluid. Heat released in the throttle is discharged directly into the tank, and the pressure in the outlet reduces the danger level of the emergency situation consequences in the event of an unauthorized change in the sign of the load to be overcome. The quality of control is, mainly, assessed by the type of load characteristics, i.e. dependences of the output link speed and its developed power on the load to be overcome, as well as by the control efficiency (the total efficiency value of the regulating and executive subsystems of the hydraulic drive). The dependence of the dynamics and kinematics of the hydraulic drive on the control methods are of particular interest. The proposed paper, based on the developed mathematical models and their testing for specific sizes of hydraulic cylinders presents the numerical values of the load characteristics and dependences of the total efficiency on the load value to be overcome. Shows that the speed load characteristic steepness of an executive hydraulic cylinder and the sign of its derivative are determined by the throttle control method. The greatest power developed by the output link of the hydraulic engine is shifted to the loads that are 50 ... 70% of their maximum value. As a result of theoretical studies using numerical calculation methods, a technique has been developed for selecting a throttle control method with an assessment of its quality and efficiency. The results of the conducted studies expand the capabilities to forecast the dynamics and kinematics of the output link of the hydraulic drive at the stage of its engineering design.