| The automobile is now the world most important transportation and has close contacting with people's production and living. However, the people while enjoy the automobile civilization, but also have to face the negative impact brought about by motor vehicles: energy consumption and environmental pollution. Therefore the development of energy-saving, environmentally-friendly vehicle of the society is increasingly becoming an important task. And hybrid vehicles with energy-saving, low pollution emissions, long continued driving miles , not to change the infrastructure and so on, caused by Governments and research institutions of high priority.Hybrid electric vehicles are the most popular current research hybrid vehicles, and are successful in mass production. However, the traditional electric hybrid vehicles with a low battery power density, small red or discharge frequency, can not be quickly save a lot of braking energy ,can not meet the requirements of a lot of energy release and recovery rapidly when urban transport vehicles frequent start-up and braking. Therefore, hybrid electric vehicle development and promotion has been limited.It is in this case, the hydraulic hybrid vehicle came into being. Compared to electric hybrid vehicles, hydraulic hybrid vehicles with the merits of high power density energy storage and fast energy conversion speed can recover braking energy efficiently. Therefore, the study of the hydraulic hybrid vehicle has great significance.The item from the scientific and technological development project of Jilin Province——Critical technology of hydraulic hybrid vehicle. This paper studies parallel hydraulic hybrid vehicle braking energy recovery system. The system manages the hydraulic pump / motor, accumulator and other units dynamically by using advanced control strategy, and distributes mechanical friction braking torque and Energy recovery braking torque dynamically in order to recovery braking energy efficiently. The braking energy recovery system based on different vehicle driving cycle needs forms a composite braking torque without sacrificing the braking performance to improve vehicle fuel economy and lower emissions targets.This project aims to enable the hydraulic hybrid technology to improve as soon as possible, applies hydraulic hybrid technology to transport system so as to contribute our own forces to reduce vehicle fuel consumption and save the limited resources, protect the environment and maintain sustainable development of humanity.This paper made the following:(1) Introduced the basic types of the hydraulic hybrid vehicle, there are series, parallel and hybrid-type. And introduced the structure, working principle and the advantages and disadvantages. Under the actual situation and the requirements of the project, we decided to adopt the parallel hydraulic hybrid vehicles as the project system and described in detail the working process of the system.(2) Through theoretical analysis of the braking system, the braking force distribution control strategy was proposed. The front wheel, rear wheel braking force was distributed in accordance with the ideal braking force distribution I curve and I proposed proportional control and maximum braking energy recovery control of the two control strategies for the rear wheel (driving wheel) distribution of the regeneration braking force and mechanical braking force, and discussed respectively.(3) According to the requirements of the entire braking system performance, the mathematical model of the parallel hydraulic hybrid vehicle was established and the front and rear wheel braking force distribution model was established in accordance with the ideal braking force distribution I curve. At the same time, I calculated and analyzed the two key hydraulic components: the hydraulic accumulator and the pump / motor.(4) Through the established mathematical model of the braking energy recovery system, the brake energy recovery system controller was studied. By using fuzzy control as its control strategy, the controller can distribute the regeneration braking force and mechanical braking force and meet the performance requirements of the hydraulic hybrid vehicle and obtain a better economy and lower fuel consumption.(5) By using SIMULINK module and M language of MATLAB in the final of the full text, the simulation of the parallel hydraulic hybrid vehicle braking system was made in two conditions. The simulation results was compared and analyzed, and the project research was completed.The simulation results show that, by inducting hydraulic energy recovery units, the new type of hydraulic energy concrete mixer truck can be made about 10% -20% of the energy saving effect. In this paper, simulation results show that the establishment of the parallel hydraulic hybrid vehicle braking system simulation model is correct and effective. By using fuzzy control, dynamic distribution of regenerative braking torque and mechanical friction braking torque has reached good results. In the premise of ensuring brake safety braking energy had been reclaimed effectively, which has great practical significance on energy saving and environmental protection. Putting forward and studying the issues has a certain practical value for research and development of hydraulic hybrid vehicle. |
PDF Full Text Request