Study And Simulation Of The Characteristic Of Hydraulic Mechanical Continuously Variable Transmission

To improve the vehicle comfort and reduce energy consumption and vehicle emission pollution is the primary solution in the modern automobile industry, the continuously variable transmission as a system with its "no loopholes" in the continuity of the drive way, which can accord to the road conditions and the engine-level realization of a working state of the transmission ratio changes, making the engine always working in the high-performance operation and making the Vehicle and the external environment to achieve the best matching, so that the vehicles can travel on the best performance, moreover, the CVT transmission have no shift jump and slow down the car speed in the process of shifting ,improving the vehicle comfort and safety. Obviously, the continuously variable transmission adapts the action of the auto industry development. At the same time, continuously variable transmission is also easy with today's advanced computer technology connected together, constituting a continuously variable automatic transmission, and improving the value of their research.Now , the most widely used Applications of continuously variable transmission in the automotive sector are belt and chain, but the torque capacity is limited, which generally have applications in the light vehicles. The heavy and middle vehicles'application of continuously variable transmission is limited by a lot of restrictions. In order to solve this problem, hydraulic mechanical continuously variable transmission has developed in many countries, hydraulic mechanical continuously variable transmission is posed by two parts: Machinery parts and Hydraulic parts ,the transmission has managed to maintain the hydraulic transmission's advantages of a soft smooth and a combination of mechanical transmission's the high efficiency and rapid response strengths. Theoretical study abroad have stared by several decades, but at that time, due to the level of technology and manufacturing constraints, it is relatively slow development until the sixties and seventies of the last century, before the beginning of the commercialization of hydraulic machinery, especially in the last century the nineties, the United States and Britain have been used a large number of hydraulic machinery and equipments in the defense industry, and widely used by Japanese companies in the civil engineering machinery, and have achieved great social and economic national interests. With the increasing sophistication of modern society and the progressive shortage of resources, people have more and more attention to energy issues, the use of brake energy regeneration technology is the vehicle energy recovery and reuse of part of the more important was a growing number of people research, as a result of the characteristics of the hydraulic mechanical transmission, the transmission can be achieved in the mechanical and hydraulic can convert between the positive and negative, and hydraulic energy storage with a longer period of time to preserve energy and have greater power density characteristics, it can be to address this area of energy recovery and reuse of the problems in public transport vehicles are now examples of successful application. All above are sufficient to explain the success of the hydraulic mechanical transmission and study the need for hydraulic mechanical transmission. In the light of this, the paper studies hydraulic mechanical continuously variable transmission of the theoretical analysis and simulation application.1,Introducing briefly the development and kinds of the continuously variable transmission and explaining the mechanical structure of the composition and the basic principles of the hydraulic mechanical continuously variable transmission , describing the machinery of the status quo and prospects , pointing out the advantages of the hydraulic mechanical continuously variable transmission, defining the purpose of the study papers and significance.2,Studying the characteristics and the nature of mechanical hydraulic continuously variable transmission, explaining the characteristics of convergence on the structure of the sub-transmission and the sub-transmission's characteristics, through comparative analysis, to identify suitable for automotive hydraulic mechanical transmission drive system programs: sub - Department of moment-speed transmission-type program, and on this basis, finishing the study of the rate applicable to the program features and power characteristics of the application for the real vehicle has laid a theoretical foundation for design. what conditions should pattern of the relationship between the parameters satisfy by giving the geometric structure of type transmission, which lays a theoretical foundation for the application of vehicles design.3,For the given parameters of the real vehicle power systems ,completing match, after selecting the engine, through the theoretical study and practical application of the conditions of the hydraulic mechanical continuously variable transmission, selecting for the hydraulic speed control system, designing the appropriate mechanical transmission parameters, completing the design of a set of hydraulic mechanical transmission, and transmission characteristics of this program are described.4,The establishment of a hydraulic mechanical transmission of the mathematical model of the program, some components of working conditions in some of the movement characteristics of the analysis and simulation study. By Using engine test data to establish the torque, fuel consumption numerical models and identify the driving force of the engine and the economic curve, the driver found a different engine under the intention of the best speed, the control strategy for the establishment of continuously variable the foundation. The establishment of the engine, transmission and control of the vehicle with the PID of the mathematical model, and a variety of vehicles in the operation of the actual working conditions of the simulation, simulation results show that the transmission is designed to be satisfactory.5,Expanding the hydraulic mechanical transmission apply, conducting the study of the braking energy recovery by using the accumulator, building the model of accumulator and simulate. simulation of the vehicle in the braking process, the gas pressure in the accumulator, the gas volume and the energy absorbed by the process of change. Simulation results show that the accumulator can be highly efficient absorption of braking energy. In this paper, the hydraulic speed control system in the choice of the time, and not the use of displacement than the scope of choice, whether it can be passed to the output than to optimize the use of in order to increase their transmission efficiency, has not yet been determined. Due to the restrictions did not conduct the actual vehicle test results had not been for the actual verification.