Research On Simulation Of Hydro-pneumatic Buffer For Electric Multiple Units Train

In recent years, the speed of the train has been improved for six times in China to meet people's travel requirement and a large number of high-speed passenger cars was in operation. When people enjoy the pleasure brought about by the railway speed increased, security issues of the train run at high speed is concerned. As a result of the performance and capacity of the current hook buffer mechanism is not match for the high speed train, which leads to the longitudinal impact between the body increased, the likelihood of coupling faults and derailment of trains also increased, and the comfortable of the passenger and the integrity of the cargo can not be guaranteed, therefor, developing a new type of high-capacity and low-impact buffer is a top priority.Hook buffer mechanism is one of the most elementary and also the most important assembly in vehicles. It is used to connect trains to keep them definitely far away from each other. In addition, it can also impress and buffer longitudinal forces and impact forces generated in trains running or shunting works. With coming into service of recently introduced CRH5 high speed of 200 km/h Electric Multiple Units Train(EMU), the research on up-taking skills of EMU of this type and realizing localization of the skills is ardently conducted. The core energy-absorbed component of buffer mechanism adopted by CRH5 EMU is Hydro-pneumatic Buffer. This buffer employs a new-style damping structure, and utilizes nitrogen's characteristics of non-fatigue and low volume modulus, to obtain advantages of excellent energy-absorbed capability, short rebound time, rapidly rising of buffer capacity and high efficiency of absorbing energy. This buffer is one of the ideal buffer equipment presently, which, as a shock resistance and buffer, can be extensively applied to engineering fields such as transportation, electric power, architecture and other power machine. Therefore, research on Hydro-pneumatic Buffer has a wide market space and development perspectives in our country.At present, domestic research on this starts-up relatively later. Domestic locomotive mostly adopts rubber buffer and spring buffer, while research on Hydro-pneumatic Buffer mainly concentrates in individual colleges and universities and research institutes. However, these researches are mainly aim at single buffer's characteristics. Only making experiments on drop hammer test-bed, few researchers do analysis putting buffers between vehicles. As for several buffers in train marshalling, the analysis is blank. When buffer is placed in trains, its working conditions and experiment situation vary a lot. For instance, group impact occurred in shunting operations and various external force acted on the vehicle in train running, all of these made up of a quite complex system In different conditions, buffer's dynamics characteristics have a great difference. It is difficult to analyze dynamics characteristics of the entire system only using research result of a single buffer. Therefore, it is essential to establish train formation and study the entire system.This study is a part of technology localization of the introduction of 200 km/h EMU by Changchun Bus Factory. The research on hook buffer which could apply to 200 km/h EMU can provide a reference value for our own research. Through consulting foreign patents, referring to domestic and foreign literature, drawing on advanced design and simulation methods of hook buffer from domestic and international, by comparing several existing hydro-pneumatic buffers characteristics and according to evaluation index of hook buffer provided by partners, the mathematical model of hydro-pneumatic buffer in this paper was established, then the simulation mode between two train carriages was established, and The dynamics characteristics under train and shunting operations condition were analyzed. Therefore, the buffer system models which consist of eight units train was set up, the dynamics characteristics of the every buffer under different conditions was analyzed, providing a theoretical basis for the design and choice of the hydro-pneumatic buffer for EMU.The major work has been done in this paper as follows:1. Identifing the structure of the object of the study. This paper first determined the internal structure form of the hydro-pneumatic buffer is porous structure, based on analysis of several hydro-pneumatic buffer structure features and performance characteristics. According to the patent information and the literatures provided by Changchun Passenger Car Factroy, the structure paramaters of porous structure of the hydro-pneumatic buffer were determined.2. Establishing the mathematical model of the buffer system. Based on the theories of hydrodynamics, thermodynamics and the mechanism of longitudinal impulse of train, the parameters and structural of the hydro-pneumatic buffer, ring reed and rubber bearing were discussed in this paper, then calculated the capacity of the buffer and determined the evaluation index of the buffer performance characteristics. The mathematical model of the hydro-pneumatic buffer between two vehicle is established by analyzing the layout of the entire vehicle systems and the relation of the parts based on vehicle dynamics, make a good foundation for subsequent simulation analysis.3. The buffer simulation model is developed and the static and dynamic tests were maded to study the characteristics of the hydro-pneumatic buffer. A simulation program of the system has been designed in Simulink module of MATLAB language, then the static test was maded. The simulation experiment results demonstrate that the static test could not clearly express the dynamic characteristics of the hydro-pneumatic buffer, the dynamic test is needed. The dynamics characteristics of a single buffer under train and shunting operations condition were analyzed between two train carriages in this study, analysised under the brake is 300 kilonewton and 1200 kilonewton, and relativistic velocity is 1 meter per second and 1.5 meter per second included. The simulation results accorded with the requirements of the hook buffer assessment report which provided by Changchun Bus Factory. The influence of individual impact speed, individual impact mass, individual orifice area and individual oil elastic modulus and other parameters on the buffer characteristics were discussed in detail. It had provided a valuable reference for the follow design. The dynamic simulation results showed that this buffer has high capacity and quick increase of buffer force.4. Establishing the simulation model of train marshalling and making a dynamic analysis. To the question in the traditional design only research for a single buffer, this study suggest that it is unable to meet the need of the dynamics analysis of the entire hook buffer system under the condition of Marshalling run. Therefore, the buffer system models which consist of three and eight units train were set up, the dynamics characteristics of the every buffer under different conditions was analyzed,it is also the innovation of this article. Through comparing the simulation results with the theories in "vehicle engineering" and "heavy-duty train systems dynamics" compiled by Yan JunMao, the rationality and effectiveness of the model was validated.This paper analyzed the simulation results curve, validated the choice of porous structure of the hydro-pneumatic buffer is reasonable. Based on the analysis of a number of experiments results under different conditions, different marshalling forms, different impact modes, it is proved that the buffer rebound slightly and power absorbed well, and it is more similar with the ideal performance curve, providing a simulation model for the design and performance forecasting of the hydro-pneumatic buffer for high-speed EMU.