Providing Cavitation-Free Operation of Hydraulic Systems under Passing Load in Hydraulic Actuator

Liliya Salimovna Musina,Sergey Yurievich Konstantinov,Ramil Salimovich Musalimov,Dmitry Vladimirovich Tselischev,Vladimir Aleksandrovich Tselischev

doi:10.5539/mas.v9n4p276

Abstract

The problems of braking and positioning of hydraulic actuators are an integral part of output speed control in hydro-pneumatic actuators. This article is focused on a hydraulic braking of driven elements of machines and mechanisms which is carried out by devices known as brake valves (counterbalance, load control, over-centre valves). Brake valves are used to exclude overrunning speed under passing loads when the external load direction coincides with the direction of movement (rotation) of the hydraulic actuator. They provide a constant pressure in pressure line and prevent cavitation. In this article the design and operation of brake valves are analyzed. The need for brake valves in hydraulic machines with hydraulic actuators under a passing load is proved. As a result of theoretical research a mathematical model of dynamics of hydraulic actuator with a brake valve has been developed. This model unlike others takes into account the design of main and control spools of the brake valve. The problem of logging-running unit braking is solved by the use of the hydraulic brake valve as a part of hydraulic logging system.

Highlights

1.1 Introduction to the Problem of BrakingAt present the problems of experimental theoretical simulation of automatic braking systems used in hydraulic and pneumatic units are investigated insufficiently, but computer simulation and modern application package can solve the problems of analysis and synthesis of hydraulic and pneumatic brake devices
The analysis of technical literature on hydraulic braking systems shows that the problem of hydraulic actuator braking under passing load is rather complicated and requires a careful performance calculation and selection of brake devices design (Raines, 1980; Levitsky and Tsuhanova, 1988)
Pressure drop to a level of saturated vapor pressure of liquid results in cavitation accompanied by rapid release of gas from the liquid and foam in pressure line, unstable work of a hydraulic system which can lead to uncontrollable rotation of a hydraulic motor and freight fall

Summary

Introduction

At present the problems of experimental theoretical simulation of automatic braking systems used in hydraulic and pneumatic units are investigated insufficiently, but computer simulation and modern application package can solve the problems of analysis and synthesis of hydraulic and pneumatic brake devices. These problems force to search new structures by developing generalized variants of the problems solutions, analyzing these options, research forecasting, finding compromise solutions under multicriteriality and uncertainty. There are different types of brake devices applied mainly for braking of working units and links of machines with hydraulic and pneumatic actuators (He et al, 2012; Filipov et al, 1983)

Methods

Results

Discussion

Conclusion