Research On The Vehicle Energy-saving System Based On Hydraulic Transformer

With the worldwide rapid development of industrial technology, modern vehicles are heavy-duty high-speed development of vehicles that come with the safety, reliability and low power issues such as the growing cause for concern. Nowadays, saving energy has become the measure of a country's energy utilization of a comprehensive indicator of quality, but also a level of national science and technology an important symbol. Therefore, domestic and foreign scholars have actively a lot of vehicles study in order to enhance the economy and power, put forward the application of the secondary regulatory element of the fluid to drive vehicles recycling energy research.At present, the hydraulic transformer is a kind of the latest secondary regulation theoretical technique, which has the ability to realize energy recovery and regeneration with one and several pressure-coupled executive components working in a constant pressure network. It adapts to changes of the external load by adjusting the inclination of the flow distribution plate of a hydraulic transformer. Therefore, not only does it possess fairly well dynamic and static characteristics, but also in some conditions, the hydraulic transformer can serve as a pump to recover kinetic energy or gravity potential energy. When use it the accumulator in the process of deceleration or brake of vehicles, the accumulator can be more effective recycling Energy. Therefore, it is no doubt that the technology has an important theoretical significance and application value in the energy shortage today.In this paper, energy-saving system for the hydrostatic driving vehicle based on hydraulic transformer is studied in deep and width. after The mathematical model of the energy-saving system is established, which Including Mathematical model of the braking system,Mathematical model of regulation of hydraulic transformer,Accumulator math model,Mathematical model of electro-hydraulic servo proportional control etc. On this basis to calculate the hydraulic transformer energy efficiency of vehicles can improve about 33%, Moreover it study up on the Different control methods of the hydraulic transformer valve plate, Simulation analysis showed that the control method of fuzzy PID control method is reasonable.The Main content of thesis as follows:The chapter 1, after consulting numerous data home and aboard. Firstly, the power system and driven forms of the hydraulic renewable energy system is summarized. Secondly, an application Overview of Hydraulic hybrid drive system applies to the automotive applications is described. Finally, the significance of this research and the main content is proposed.The chapter 2, Design philosophy and structure of the composition of hydrostatic driving vehicle are introduced. And working principle of Start - speed up - the road - slow down - the braking status is analyzed. Described the working principle of the hydraulic transformer and its energy-saving idea, and Set up mathematical models of vehicles. The mathematical models Including Mathematical model of the braking system,Mathematical model of regulation of hydraulic transformer,Accumulator math model,Mathematical model of electro-hydraulic proportional control etc. It theoretically analyzed the characteristics of the system. The chapter 3, the mathematics model of valve angle adjustment control of hydraulic transformer was built and the simulation was completed. When it selects reasonable parameter, the system is stable and reasonable by the bode diagram judged. After the bontrol strategy used PID,FLC,Fuzzy-PID to simulation research, system response curves and error curves is designed. The basic performance and robust performance of the three kind of controllers is analysis, which including maximum overshoot,rise time,IE,IAE,ITAE,ISE and ITSE. Then studied control performance of fuzzy PID of combination FLC and PID forms and adaptive Fuzzy-PID. Comparison results show that the Fuzzy-PID control method is reasonable and prefect, which can be used to control system of the hydraulic transformer.The chapter 4, static and dynamic characteristics of accumulator, displacement and out pressure characteristics of hydraulic transformer based on mathematical model of Accumulator and the hydraulic transformer was analyzed. When selected the accumulator volume of 40L and 63L,the simulation system on saving-energy efficiency based on hydraulic transformer was completed. The simulation results shows that when the braking speed 45km/h,the energy recycling of accumulator are 2.66×10~5J and 4.19×10~5J.However, the energy recycling of accumulator base on hydraulic transformer are 3.97×10~5Jand 6.25×10~5J.Therefore,hydraulic transformer is saving energy 1.31×10~5J and 2.06×10~5J.Hydraulic transformer may be improve relative energy-saving rate of about 33% at the original energy-saving systems when the system is perfact state when the system is prefact state.The chapter 5, based on the mathematical model of energy-saving systems and the existing components in the laboratory, the test of the hydrostatic driving vehicle energy-saving system was designed. Application of delphi language to build fuzzy PID control system, and used to single-chip write the fuzzy PID control-conditioning systems. The test-rig system was designed and experiment. The simulation results coincide with the experimental ones very well. The research shows that fuzzy PID control system write by single-chip is a reliable device, and can improve the kind of indicators of hydrostatic vehicle saving-energy system.The Chapter 6, some conclusions are given. Because of the hydraulic transformer is the new components ,which is not applied in practice yet,and the target properties of hydraulic transformer are exploring. Therefore, some new views are put forward in the future.