Research On Cushioning Stuctures And Processes For Hydraulic Cylinder

Hydraulic drive and control system is one of control systems which synthesizes mechanism, electronics and hydraulic-drive technologies, and which has been widely used. With the development of mechanical industry, the system has heavier load, higher pressure and higher speed. So it is very important that we discuss the piston's cushioning problem of the hydraulic cylinder. To aim at the operation and cushion of the cylinder piston, this thesis mainly researches on different inside-cylinder cushioning structures (namely the column-shape, taper-shape, sidestep-shape, flute-shape and parabola-shape plunger piston and the flat-shape throttling cushioning structure which is different from the plunger pistons.) and the processes with the three-stage analysis of across sectional area pressure shrinking, sharp edge throttling and aperture throttling. And it also analyses and compares the effects, points out the situations in point they can be used and summarizes some factors which should be considered when inside-cylinder cushioning structures are designed . And it summarizes and analyses the mathematical models of the electro-hydraulic proportion /servo valve-controlled cylinder cushioning control system which can be used for out-cylinder cushioning control. Then it researches on the cushioning experiments of this system and the flat-shape throttling cushioning structure. The results of experiments match the conclusions of theoretical analysis. It's results can be used in the design, performance and reliability improvement, so it is significant in engineering application. The whole thesis consists of several sections as follows:Chapter 1 mainly states the feature, the current application situation and the foreground of hydraulic drive and control system. Then it points out the importance of cushioning technology to hydraulic drive and control system and introduces various cushioning methods and research situations at home and overseas. At last it sums up the main content of the thesis and the research work.Chapter 2 firstly introduces the basic cushioning theory of hydraulic drive and control system. It briefly researches on inside-cylinder cushioning methods and processes through theoretical analysis. With the three-stage analysis method, namely across sectional area pressure shrinking stage, sharp edge throttling stage and aperture throttling stage, it establishes separately every stage flow equation. Thereout it establishes the cushioning process mathematical model of five kinds of cushioning plunger pistons, namely the column-shape, the taper-shape, sidestep-shape, flute-shape and parabola-shape plunger piston. At the same time it points out and establishes flat-shape throttling cushioning process modeling, which is different fromplunger pistons. On the base, detailed simulations and calculations in such theory have been done, then the regularity of structure parameters of every inside-cylinder cushioning devices to cushioning processes and effects have been discussed and compared. Also it points out their adaptive situations. We also contrast the experimental results of the fiat-shape throttling cushioning process with theoretical conclusions.Chapter 3 firstly researches the mathematical model of the electro-hydraulic proportion /servo valve-hydraulic cylinder cushioning control system. And through simulations and calculations it researches on and analyses the cushioning process. Through the simulation and analysis the regularity of some structure parameters to cushioning processes and effects. And the conclusions can be used to guide us to research on the out-cylinder cushioning control experiments.Chapter 4 is the experiment part of the thesis. Firstly it introduces the theory and design of the electro-hydraulic proportion /servo valve-controlled cylinder cushioning control system experiment flatform. The fiatform mainly consists of hydraulic part and electric control and data aquisition part. And it introduces the index of some components and the method of experiment. The aim is to find the factors whic...