【作者】 郝赫；

【导师】 王登峰；

【作者基本信息】 吉林大学 ， 车辆工程， 2011， 博士

【摘要】 随着中国经济的迅猛发展以及迅速增加的跨区域公路物流运输业务,人们对重型载货汽车的需求量越来越大,与此同时,当今的物流产业不仅要求将货物快捷安全的送达目的地,而且对重型载货汽车各方面动力学性能也提出了更高的要求,汽车生产厂商以及用户对此尤为关注,因此如何改善重型载货汽车的结构、提高其动力学性能已成为载货汽车制造厂商及科研单位所追求的目标。本文结合国家"863"高技术研究发展计划项目《重型商用车集成开发先进技术》(项目编号：2006AA110105)子项《重型汽车底盘匹配与性能优化研究》进行研究。论文以国产某重型载货汽车为研究对象,利用多体动力学方法及虚拟样机技术,在ADAMS软件环境下建立了全浮式驾驶室悬置系统、变截面少片钢板弹簧前悬架系统、中、后桥四气囊空气悬架系统、前桥钳盘式、中、后桥凸轮鼓式制动器系统、动力总成系统、转向系统以及横向稳定杆等多体动力学子系统模型。同时利用有限元方法建立了车架及驾驶室有限元模型,通过将各子系统模型进行综合进-步建立了整车刚弹耦合虚拟样机模型。依据国家标准《汽车平顺性随机输人行驶试验方法》(GB/T 4970-1996)、《汽车操纵稳定性试验方法》(GB/T 6323.3-94-GB/T 6323.6-94)以及《汽车制动系统结构、性能和试验方法》(GB 12676-1999)与ECE R13号法规中附录4《制动试验和制动系统性能》中的相关规定,在ADAMS软件环境下,对整车虚拟样机模型进行了仿真分析与研究,并通过相应的实车道路试验验证了模型的有效性。通过改变车架弹性模量的方式在不改变车架模态阵型的基础上改变了车架低阶固有振动频率,从而改变了车架的弹性。研究了车架弹性不同对整车行驶平顺性以及操纵稳定性的影响。研究结果表明,适当的提高车架的刚度可以改善重型载货汽车行驶平顺性,提高不足转向特性,降低转角脉冲输入试验中谐振峰水平值,但是会增大车箱侧倾度。分析了多轴汽车在制动过程中的受力情况,建立了多轴汽车制动时地面法向反作用力数学模型以及制动器制动力数学模型,推导出理想多轴制动器制动力分配空间I曲线的计算公式,并对多轴汽车在不同附着系数路面上的制动过程进行了分析。利用得出的结论得到了本文所研究重型载货汽车的空间I曲线计算公式。推导了当某一车轴抱死,其它两轴没有抱死时,在各种值路ψ面上制动时各轴地面制动力的关系面组,即f、m、r面组。分析了三轴汽车在不同附着系数路面上制动时可能出现的情况,从而设计出本车实际前、中、后轴制动器制动力分配线(空间β线),并验证了空间β线的合理性。将所设计的空间β线通过ADAMS/Solver求解器中的函数输入到虚拟样机模型中,进行了满载及空载条件下高附着及低附着系数路面上的整车制动性能仿真分析,仿真结果符合ECE法规中规定的要求,并且附着系数得到了很好的利用,整车制动效能得到提高。结合预测控制技术及模拟控制技术制定了在高附着系数路面、低附着系数路面以及对接(由低附着系数路面过度到高附着系数或相反)路面制动时的门限值控制逻辑,并利用Stateflow工具箱建立了相应的控制器模型,同时利用MATLAB/Simulink模块建立了参考车速估算模型以及气压驱动系统模型,进而建立了带有制动防抱死系统的三轴气动制动系统模型。利用MATLAB/Simulink及ADAMS/Car模块建立了带有ABS的重型载货汽车整车模型,同时在高附着系数路面、低附着系数路面以及对开与对接路面上进行空、满载条件下整车制动性能联合仿真分析,结果表明,所设计ABS控制器模型取得了良好的制动控制效果,提高了整车制动效能,为重型载货汽车ABS的设计和开发提供了基础。更多还原

【Abstract】 With the rapid development of Chinese economy and gradually improving inter-regional logistics, the nation’s demand for heavy-duty truck is increasing. At the same time, the modern logistics industry not only requires deliver the goods to destination efficiently and safely, but also demands high dynamics performances of all aspects of heavy-duty truck, which is closely followed with interest by automobile manufacturers. Consequently, how to improve the structure and dynamics performances of heavy-duty truck will become the pursuing target for vehicle manufacturers and research institutionsThis paper was completed based on the research of "Chassis Matching and Performance Optimization of Heavy-duty Truck", which was a subproject of National High-tech R&D Plan (863 Plan) of China"Integrated Advanced Technology of Heavy-duty Truck Development" (No.2006AA110105-6). Based on multi-body dynamic method and virtual prototype technology, a rigid-flexible coupling model of a heavy-duty truck was built in ADAMS/Car software environment, including full-floating cab mount system, taper-leaf-spring suspension system, braking system with two disc brakes and four drum brakes, air spring suspension system, steering system, powertrain system, etc., at the same time, the frame and cab were generated as elastic parts with FEA method.In accordance with National Standard GB/T 4970-1996, "Method of random input running test automotive ride comfort", GB/T6323.3-94～GB/T6323.6-94, "Controllability and stability test procedure for automobiles", GB 12676-1999, "Structure, performance and test methods of automotive braking system" and ECE R13, some simulation calculations of heavy-duty truck were implemented in ADAMS/Car and the validity of rigid-flexible coupling model was verified by comparing the simulation results with experiment data.The frame flexibility was increased and decreased through modifying the elastic modulus of frame. It was studied how the ride comfort and controllability and stability of heavy-duty truck were influenced by different frame flexibility. The result shows that increasing frame stiffness properly is very helpful to improve ride comfort and under-steer characteristic, and is able to reduce the value of resonant peak level, but the roll angle will increase with large frame flexibility.Based on the analysis of force of vehicle with multi-axles during brake, the mathematical models of axle loads and brake forces were established, and then the ideal braking forces distribution curve with multi-axles (space curve I) was deduced, in addition, the braking process that the multi-axles vehicle traveled on different adhesive road surface was analyzed and discussed. According to the conclusions above, the loaded and unloaded space curve I of heavy-duty truck built in this paper were acquired. Meantime, the surface groups of braking force relationship on different adhesive road surface under condition of one of axles locked(f、m、r surface group) were obtained.Actual loaded and unloaded braking force distribution curves (space curveβ) of heavy-duty truck were designed and devised and their validity were verified by analysising the braking process on different adhesive road surface. In addition, space curveβwere programmed in virtual prototyping software with ADAMS/Solver functions, and then some simulation were performed in ADAMS/Car software environment to analyze heavy-duty truck braking performance on high and low adhesive road surface under different load conditions. The simulation results met the requirements of ECE regulations, and the percentage of utilization of maximum tractive force of each axle was improved.Logic threshold control strategies were developed that the heavy-duty truck brakes on high and low adhesive road surface and the road surface with adhesion coefficients ranged from low to high and high to low, and the corresponding controller model was established in MATLAB/Stateflow. Simultaneously, reference speed estimation model and brake chamber model were built in MATLAB/Simulink, and then three-axles pneumatic brake system model of heavy-duty truck with ABS was accomplished.A rigid-flexible coupling model of a heavy-duty truck with ABS was completed in the virtual environment with ADAMS/Car and MATLAB/Smulink, and the Co-simulation calculations were implemented under different road surface conditions. The results demonstrated that braking efficiency was improved with ABS, and this controller provides a basis for further guide in ABS product R&D stage.更多还原