【作者】 宋涛；

【导师】 刘昕晖；

【作者基本信息】 吉林大学 ， 机械电子工程， 2018， 硕士

【摘要】 转向系统能够对车辆的机动性、驾驶平稳性、安全性、经济性等性能造成影响,其设计的优劣直接关系到对车辆性能的整体评价。针对狭小地域和复杂地形下应急救援车辆的通过性难题,本文基于国家重点研发计划“高机动多功能应急救援车辆关键技术研究与应用示范”课题四——“狭小地域和复杂地形下的行走装置关键技术”项目,对应急救援车辆转向系统的关键技术展开研究。螺旋摆动油缸被创新性地应用于液压动力转向系统,带动车轮完成大角度范围内迅速、准确、安全、平稳的转向动作。前轮、后轮、四轮、蟹行、原地转向等五种转向模式的自由切换,使应急救援车辆能够应对狭小的地形和复杂的工况。将负载敏感系统和阿克曼转向原理相结合,通过对电比例换向节流阀阀口开度及其阀口前后压差的独立控制,实现了四个螺旋摆动油缸与外负载无关的独立的方向和角度的输出。以自主研发的应急救援车辆为载体,介绍了组成多模式四轮独立液压动力转向系统的三个模块——方向盘模块、电控模块、液压执行模块;分析了液压动力转向系统关键元件——负载敏感变量泵、螺旋摆动油缸、负载敏感多路阀的负载敏感变排量动力输入原理、扭矩输出原理、压力和流量控制原理,并分别进行了数学建模;研究了液压动力转向系统的负载敏感回路,并分析了转向系统在前轮、后轮、四轮、蟹行、原地转向等转向模式下的液压系统工作原理。对搭载了多模式四轮独立液压动力转向系统的应急救援车辆在转向过程中的运动特性进行了研究。在分析了轮胎在转向时的侧偏特性的基础上,建立了五种转向模式下应急救援车辆的运动学模型,总结出转向时方向盘、轮胎偏转角、电比例换向节流阀阀口开度三者之间的关系,并且建立了应急救援车辆的四轮独立转向动力学模型。在AMESim中搭建了多模式四轮独立液压动力转向系统的1D模型,在Motion中搭建了应急救援车辆的多体动力学3D模型,联合仿真结果表明,该转向系统实现了通过改变电比例换向节流阀的阀口开度来独立控制四个车轮偏转速度的负载敏感调节和阿克曼转向原理下的应急救援车辆多模式四轮独立转向。转向系统控制单元的PID调节与比例调节对比仿真结果表明,与比例调节相比,PID调节使系统具有更好的动态特性和稳态特性。通过车辆在多模式转向过程中的负载敏感系统工作原理及车辆运动状态的理论研究、1D+3D联合仿真研究,为自主研发的应用于应急救援车辆上的多模式四轮独立液压动力转向系统的转向性能分析及后续性能提升方案的制定,提供了理论依据及仿真数据依据。更多还原

【Abstract】 The steering system can affect the performance of vehicle mobility,driving stability,safety and economy,and its design is directly related to the overall evaluation of vehicle performance.The project is based on the National key research and development plan "key technology research and application demonstration of high mobility and multi-function emergency rescue vehicle" topic four-"The key technology of walking device in narrow area and complex terrain" Aiming at the passing problem of emergency rescue vehicles in narrow and complex terrain,the key technologies of emergency rescue vehicle steering system are studied.The spiral wobble cylinder is innovatively applied to the hydraulic power steering system,driving the wheel to complete the quick,accurate,safe and stable steering movement in the large angle range.The free switching of the five steering modes,such as the front wheel,the rear wheel,the four wheel,the crab line and the pivot steering,enables the emergency rescue vehicles to cope with the narrow terrain and complex conditions.By combining the load sensitive system with the Ackerman steering principle,the independent direction and angle output of four spiral oscillating cylinders are independent of the external load through the independent control of the opening degree of the valve opening and the pressure difference between the front and back of the valve port.Based on the independent research and development emergency rescue vehicle,the three modules of a multi mode four wheel independent hydraulic power steering system,namely steering wheel module,electronic control module and hydraulic execution module,are introduced.The load sensing and variable displacement power input principle of load sensing variable pump,the principle of torque output of spiral wobble cylinder and the pressure and flow control principle of load sensing multiway valve are analyzed.The mathematical modeling of load sensing variable pump,screw swing cylinder and load sensitive multi way valve is carried out respectively.The load sensitive circuit of the hydraulic power steering system is studied,and the working principle of the hydraulic system in the steering system is analyzed in the steering mode,such as the front wheel,the rear wheel,the four wheel,the crab line and the pivot steering.The motion characteristics of emergency rescue vehicle equipped with multi mode four wheel independent hydraulic power steering system during steering are studied.Based on the analysis of the cornering characteristics of tires during steering,five kinematic models of emergency rescue vehicles under steering mode are established.The relationship between steering wheel,tire deflection angle and valve opening of electric proportional commutation throttle is summarized.The four wheel independent steering dynamics model of emergency vehicle is established.A 1D model of multi-mode four wheel independent hydraulic power steering system is built in AMESim.A multi-body dynamics 3D model of emergency rescue vehicle is built in Motion.The combined simulation results show that the steering system realizes the multi mode and four wheel independent steering of emergency rescue vehicles under the principle of load sensitive adjustment and Ackerman steering principle by changing the opening degree of the valve opening to control the four tire deflecting speed.The comparison between PID regulation and proportional regulation shows that PID regulation has better dynamic and steady-state characteristics compared with proportional regulation.In the process of multi mode steering,the theory of load sensing system and the state of vehicle motion are theoretically studied.In addition,the joint simulation of 1D+3D are Researched.The theoretical basis and simulation data basis are provided for the analysis of the steering performance of the multi mode four wheel independent hydraulic power steering system applied to emergency rescue vehicles and the formulation of the follow-up performance improvement scheme.更多还原