With The Dynamic Characteristics Of The Long Pipeline Valve Control System

The large construction machinery generally has tens of actuators. All of them are powered by one hydraulic source. This leads to that some actuators may be away from the source. Then the long pipe is essential to connect the actuators with source. When the pipe is too long, the flow lag of fluid in pipe can cause many problems to the electro-hydraulic control system. In order to solve these problems, we must deeply understand how pipe influences the electro-hydraulic. This thesis is concentrated in studying and solving these problems. In this thesis, the author analyzed the valve control system with long pipe theoretically and did some experiments. Some useful and practical conclusions are reached by these studies. And at the end of this thesis, the author shows a few study directions of this project for the later researchers.In chapter 1, the background of this project was presented and the author overviewed the contribution of researchers in domain and oversea on the fluid pipe dynamics and the effect of pipe on fluid power system. After these discussions, the main objective of this research project is showed at end of this chapter.In chapter 2, the author analyzed the existing distributed-parameter models of fluid pipe. After balancing between them, a few models were considered to be suitable for this research project.In chapter 3, the two ways, in which long pipes were arranged in the valve control system, were demonstrated. And the mathematics models considering the effect of pipe were established. These models were fundamental for analyzing the effect of pipe on system.In chapter 4, based on the models deduced in chapter 3, the system dynamics analysis in frequency domain was performed. The author also balanced between the two ways of pipe arrangement. Some useful and practical conclusions were drawn in this chapter.Considering the nonlinear behaviors of system, the author also studied the step response of system in time domain by simulation in chapter 5. The content of this chapter not only demonstrated these conclusions again reached in chapter 4, but also show some new characteristics of system dynamic.In chapter 6, the author introduced the test platform for this project firstly and then showed the experimental results. These results, which were obtained by analyzing theoretically and doing experiments, were proved to be consistent with each other.In chapter 7, the author investigated the method of using accumulator to improve dynamic behaviors of the fluid power system with long pipe and gave a theoretical explanation.In the last chapter, the author looked back these research works and made a summary of the conclusions. Furthermore, the author proposed some suggestions about what should be done in the future.