| In recent years, natural disasters occur frequently, so a kind of vehicle with highmaneuverability and crossing ability is needed for transport and road wrecking. Alsoin a variety of complex terrain of the battle field, it needs vehicles with highobstacle-stability and off-road mobility to provide efficient and reliable logisticalsecurity. Thus, researchers of vehicles field both in domestic and foreign has beencommitted to designing a kind of driving system with good capacity and obstaclestability, which can run on non-structural terrain.Wheeled vehicles are the earliest ones which entered into the field of industrialand been widely used in off-road engineering vehicles. Their main advantage is that itcan rely on a relatively simple mechanism and control to realize high-speed and stablemobility, and they has higher energy utilization compared with other mobilemechanism. For wheeled off-road engineering vehicles, it contains a lot of systems,but no matter how complex the systems are, the running mechanism is very importantand it is the basis of the entire vehicle.With support of the National High Technology Research and DevelopmentProgram-the "863" project, the research team led by Professor Liu Xinhui, JilinUniversity, has successfully developed the prototype of a wheeled off-road vehiclewith2degree-of-freedom articulated body. The prototype’s driving system useshydraulic-mechanical transmission formation, which greatly improves the efficiencyof the engine and hydraulic system, and enhance the ability of vehicles to adapt to thedriving load, allowing the vehicle in climbing, cross-country, wading, ice and snowand all-terrain driving. Wherein the hydraulic drive is the most important part of itdirectly affects the dynamic characteristics of the vehicle traveling systemperformance.This paper is based on university-enterprise cooperation project-" Developing anArticulated Wheeled Off-road Engineering Vehicle with2Degrees of Freedom Body”.The prototype is as the research object, studying the dynamic characteristics of travelhydraulic system with theoretical analysis, dynamic simulation and experimentalresearch methods. This paper makes the foundation for the wheeled off-road vehicle’stravel hydraulic optimization and analysis, performance evaluation, etc.The paper’s main contents are as follows:Chapter1, expounds the research background and significance of this topic,summarizes the present status of articulated wheeled off-road vehicle’s development.Outlines the wheeled vehicles’ drive technology, especially analyzes the walkinghydraulic transmission technology in detail, and confirms the wheeled off-roadvehicle drive system’s main transmission scheme.Chapter2, prototype is as the research object, introduces the wheeled off-roadvehicle drive system’s overall scheme, analyzes the composition of the vehicle’s hydraulic system and the working principle of the common working conditions indetail. Introduces the variable pump cross-power control, the negative flow controland power conversion control principle and realization process. Meanwhile, analyzesthe working principle of the balance valve, variable motor’s automatic variablecontrol HA2principle.Chapter3, establishes the mathematical models of the components of hydraulicsystem including the main pump and its displacement control mechanism, thereversing valve, balance valve, motor and its displacement control mechanism andequivalent load. Establishes main pump-reversing valve-variable motor system’smathematical model and the balance valve controlled variable motor mathematicalmodel, and the control characteristic of the system were analyzed.Chapter4, combined with theoretical analysis, based on the AMESim softwarebuilds each component’s simulation model and simulation analysis for importantparameters of major components. For different working conditions, researched thecharacteristic of the system under constant load and increasing load and reducing load.Simulates and analyzes the pump delivery pressure response of three differentworking modes.Chapter5, with the theory analysis and simulation analysis of travel hydraulicsystem, formulates the wheeled off-road vehicle performance test for the hydraulicsystem, including no load condition, flat road condition, downhill condition andtraction condition experiment test, also the system response experiment test in threedifferent working modes. Analyzes the experimental results, to verify the correctnessof the related theory research and the simulation model, at the same time analyzes theproblems found and puts forward solutions.Chapter6, summarizes the accomplished research work and achievements, anddiscusses the work for the next stage. |
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