The Study Of Wheeled Off-road Vehicles Hydraulic Drive System Based On Hydraulic Control Technology

The engineering vehicle is required to function well not only on the smooth road but also in off-road conditions due to the characteristics of its working conditions. The travel drive system is an important component of the construction machinery. Compared with the work system, the travel drive system is required to transmit higher power, with its devices being of higher efficiency and longer life expectancy. In addition, the travel drive system is also expected to function well in such areas as speed change and adjustment, differential, drive shaft rotation direction change and reverse power transmission. Hydraulic drive technology, as a new technology, has the characteristics of other transmission modes and its own unique advantages. Thus it can better meet the needs of drive and motion of various engineering machinery. Especially in recent years, the research on travel hydraulic drive system has been greatly promoted, as China's transportation, energy and other infrastructure construction are rapidly developing, with the scale of construction and natural resources exploitation being expanding and the demand for engineering machinery being on the rise, together with the challenges brought by increasingly complex working conditions.In recent years, with the rapid development of hydraulic technology, electro-hydraulic servo technology and the research and application of the new technology of pure water medium, major breakthroughs have been made in the hydraulic drive technology, which provides favorable technical support for the development of vehicles with hydraulic drive system. At present, many sophisticated and advanced systems are developed and applied in some facilities in the hydraulic drive technology both at home and abroad, such as secondary regulation and control hydraulic drive system, synchronous hydraulic drive system. After studying the latest developments both at home and abroad, we have designed and developed off-road engineering vehicles that are self-adaptive with active suspension and multi-wheel independent drive.This paper expounds on the drive system of the off-road engineering vehicles that are self-adaptive with active suspension and multi-wheel independent drive. It introduces the method of using hydraulic resistance control technology to conduct self-adaptive and internal regulation and control over the drive system in order to ensure the balance of the tractive force. This paper analyzes the functions and control programme of the hydraulic drive system and the characteristics of its major components. It studies the principle of the hydraulic control system, with a mathematical model of the drive system being built and the system being analyzed by using simulation software.There are five chapters in this paper.In Chapter 1, the differences between the hydraulic drive technology and the traditional drive technology are explained; the merits of the drive system are elaborated; the development trends of the hydraulic drive technology and its research and application situation both at home and abroad are analyzed; the significance of the research is explained; the main content of the research in this paper is outlined.In Chapter 2, the off-road engineering vehicle, which is developed by myself, being self-adaptive with active suspension and multi-wheel independent drive, is explained in great details. The hydraulic system of the off-road vehicles is composed of two main subsystems: the six-wheel hydraulic independent drive system and self-adaptive hydraulic system with active suspension. In this paper, the focus is on the research of the hydraulic independent drive system, its working principles and the analysis of its basic functions and the control programmes of each function. In addition, the structure of the major hydraulic components and the working principles of the hydraulic independent drive system are elaborated.In Chapter 3, the drive system is analyzed; the relationship between the hydraulic drive system and the external load on the system is defined; the mathematical models of the in—wheel—motor system and the hydraulic system are established respectively. The output torque of the motor corresponds with the load of the wheels on the ground. Stress analysis of each wheel is conducted, and then the stress analysis of wheels on the same side of the vehicle is conducted, with the secondary factors being neglected. A mathematical model of the unilateral vehicle wheel system is built. The Engine energy is transferred to wheels through the hydraulic system. When a drive torque is imposed on the wheels, then the wheels will in turn impose a drive torque on the motor. A simplified mathematical model of the hydraulic system is established by applying the principle of pump-controlled motor system and the hydraulic resistance control technology. Then a mathematical model of the hydraulic system is established with the secondary factors being neglected.In Chapter 4, an AMESim software simulation environment and its fundamental characteristics are explained. A simulation model of the hydraulic independent drive system is established under the AMESim software environment, with the parameters being set. Then the simulation results are observed and analyzed under the input of Gaussian White Noise Signal to test whether the hydraulic drive system and the mathematical model are reasonable. In Chapter 5, the paper is summarized and conclusions are made. The hydraulic independent drive system presented in this paper is proved to be reasonable, and a number of deficiencies and some suggestions for the subsequent work are also made.