侧风对高速汽车行驶稳定性影响的仿真分析

汽车高速运动时的方向稳定性受侧向风的影响非常明显,其影响规律与侧风气动中心的位置密切相关。但是,对侧向风的影响有两种不同的观点,一种观点认为与气动中心和中性转向点的相对位置相关;另一种观点则认为取决于气动中心和质心的相对位置。基于二自由度汽车动力学模型,用Matlab软件对侧风引起的汽车行驶稳定性进行了仿真分析,认为汽车在侧风作用下的运动规律取决于侧风气动中心与中性转向点的相对位置。     

红岩CQ4261、CQ4161半挂牵引汽车列车风洞试验

我厂和西南交通大学机械学院合作进行了CQ4261、CQ4161兰挂牵引汽车列车风洞试验，研究了影响汽车列车气动性能的因素。本文报告了这次试验的设施、试验方法、根据试验数据整理的列车气动性能参数；利用试验结果分析了降低气动阻力对降低油耗率和改善动力性能所起的作用。     

汽车底部外形对气动特性的影响

以降低车身阻力和提高汽车的行驶稳定性为目的,对车身底部的流动特性进行数值模拟,以使通过车身底部的流动最佳化.以某轿车的1:5模型为研究对象,对汽车底部外形进行各种改型设计,研究汽车底部凸凹外形对汽车空气动力特性的影响,并对产生这些影响的原因进行了分析.模拟计算结果表明:汽车底部外形越复杂,气动阻力系数和气动升力系数越大;对气动阻力系数影响最大的是车轮,对气动升力影响最大的是轮腔.计算和分析的结论可为汽车底部外形设计和改型提供参考,也为获得复杂车身底部流动最佳化外形打下了基础.     

基于RSM的类车体气动阻力全局造型优化

全局优化减阻已成为汽车车身造型设计的必然趋势。为探索轿车车身造型气动因子控制的减阻效果,获得车身减阻全局优化方法,文中以某实车简化后的类车体为优化原型,选取6个气动因子作为设计变量,应用响应曲面法（RSM）对类车体进行全局气动阻力造型优化。结果显示,全局优化较局部优化更能体现设计因子对气动阻力系数的效应;对因子间的相关性分析论证了传统局部气动造型方法收敛于局部最优解的局限性;RSM法应用于车身全局减阻优化具有高效性,优化后的类车体更加流线化,整套方法可为汽车车身前期的气动优化提供借鉴。     

气动燃油混合动力汽车的发展现状与展望

为了缓解能源和环境双重压力，汽车行业正处于多元化时代，提出了电动汽车技术、燃料电池汽车技术、燃气汽车技术、生物质能源汽车技术等多种新能源汽车技术，这些新技术都有各自的优势和不足。文章对气动动力系统和气动燃油混合动力系统分别进行研究，同时介绍了这2种动力系统国内外发展状况，得出把气动动力系统和传统内燃机有机的结合起来，可以起到优势互补的效果，可见气动燃油混合动力汽车具有广泛的市场和美好的前景。     

汽车后视镜区域瞬态流场及气动噪声数值仿真

通过分离涡模拟(DES)进行整车外流场的三维瞬态仿真,得到车身表面压力脉动,并采用FW-H声学模型对气动噪声进行仿真分析。通过与类后视镜气动噪声试验数据相比较,验证了仿真的准确性。对有、无后视镜工况下,后视镜区域瞬态流场、车身表面压力脉动、侧窗监测点声压级进行比较,揭示了后视镜区域气动噪声产生机理,为降低汽车气动噪声提供技术支持。     

汽车暖通空调系统鼓风机气动噪声传递特性分析

以某型汽车暖通空调(HVAC)系统为研究对象,采用隔振、隔声、消声和改变壳体阻尼的方法对鼓风机的气动噪声进行了试验研究。应用相干分析、阶次分析以及频谱分析等方法,确定了43阶气动噪声源为鼓风机叶轮,确定其传递特性为叶轮旋转产生的气动力传递至电机壳体和蜗壳壳体,引起结构振动并辐射噪声,另有部分气动力产生的气动噪声通过进、出风口向外气动传播。     

汽车维修专业液压与气动实训教学资源开发和“做学合一”应用实践研究

随着汽车技术的不断发展,液压与气动系统在汽车维修领域中扮演着重要的角色。本研究旨在探讨汽车维修领域中液压与气动实训教学资源的开发与优化。通过系统性的研究,我们将分析当前液压与气动实训教学中存在的问题,并提出相应的改进方案。同时,我们将关注教学资源的设计、开发和管理,以满足学生在液压与气动系统维修方面的培训需求。本文旨在将“手脑并用”“做学合一”以及黄炎培职业教育思想应用于液压与气动实训教学资源的开发研究与实践。以解决汽车维修专业液压与气动实训教学中液压与气动实训教学资源开发不够完善、实训环节“手脑并用”“做学合一”衔接不够的问题。将实训教学环节从管理形式到教学内容进行系统性的研究,采用模块化管理,将职业素养培养有效融入技能实训整个过程中,充分调动学生学习的主观能动性和积极性。     

某SUV车型前端结构对冷却模块风量和内流阻力的影响分析

采用计算流体力学(CFD)软件CCM+对某汽车前端结构进行了参数化分析。通过提高冷却气流利用率和改善发动机舱内部气流流动,寻找到兼顾前端模块冷却流量和整车气动阻力要求的最优前端参数。经气动风洞试验和热环境风洞试验验证表明,该优化结果可行。指出,运用CFD分析优化可以在汽车设计前期介入,通过对比不同方案提升整车的综合性能。     

跨海大桥上厢式货车侧风稳定性的研究

建立了跨海桥上厢式货车的空气动力学和系统动力学单向耦合数值计算模型,并经风洞试验验证。对该模型进行仿真,以研究桥上货车在阶跃阵风作用下的高速气动稳定性,比较分析了不同类型和结构参数的挡风屏障的抗风性能及其对汽车气动稳定性的影响规律。最后提出了桥上汽车风致行车安全和桥梁抗风设计的量化评价方法。     

An investigation of the effects of pneumatic actuator design on slip control for heavy vehicles

Progress in reducing actuator delays in pneumatic brake systems is opening the door for advanced anti-lock braking algorithms to be used on heavy goods vehicles. However, little has been published on slip controllers for air-braked heavy vehicles, or the effects of slow pneumatic actuation on their design and performance. This paper introduces a sliding mode slip controller for air-braked heavy vehicles. The effects of pneumatic actuator delays and flow rates on stopping performance and air (energy) consumption are presented through vehicle simulations. Finally, the simulations are validated with experiments using a hardware-in-the-loop rig. It is shown that for each wheel, pneumatic valves with delays smaller than 3 ms and orifice diameters around 8 mm provide the best performance.     

高压无气冷喷漆划线车的发展概况和趋向

冷喷漆划线车是道路标线绘制的一种重要设备,按工作原理和结构组成可分为:机械式高压无气冷喷漆划线车、液压式高压无气冷喷漆划线车和气动式高压无气冷喷漆划线车。介绍了上述各种高压无气冷喷漆划线车的结构组成、工作原理、主要特点、应用及发展趋向。     

Wheel slide protection control using a command map and Smith predictor for the pneumatic brake system of a railway vehicle

In railway vehicles, excessive sliding or wheel locking can occur while braking because of a temporarily degraded adhesion between the wheel and the rail caused by the contaminated or wet surface of the rail. It can damage the wheel tread and affect the performance of the brake system and the safety of the railway vehicle. To safeguard the wheelset from these phenomena, almost all railway vehicles are equipped with wheel slide protection (WSP) systems. In this study, a new WSP algorithm is proposed. The features of the proposed algorithm are the use of the target sliding speed, the determination of a command for WSP valves using command maps, and compensation for the time delay in pneumatic brake systems using the Smith predictor. The proposed WSP algorithm was verified using experiments with a hardware-in-the-loop simulation system including the hardware of the pneumatic brake system.     

The Rolling Motions of Road Vehicles

This paper examines the rolling motions of vehicles with pneumatic tires. From a simplified analysis two sources of instability are identified-one related to center of gravity position and the other to tire and suspension characteristics. When a specimen vehicle is considered, it is shown that current semi-trailer design can display instability from either source.     

The Static Stability of Articulated Commercial Vehicles

This review of the state of the art emphasizes recent results that have been obtained in extending conventionalanalysis techniques to the treatment of “Highway Trains”, that is, to heavy trucks that have multiple articulation points and employ suspensions with multiple axles. Equations of motion applicable to the equilibrium turning performances of articulated vehicles are examined with respect to using analysis techniques involving steering gains, understeer gradients, effective wheel-bases, handling diagrams, and critical speeds. These examinations provide the basis for in sights into simplified approaches for understanding the steady turning mechanics of articulated, multi-axle vehicles riding on pneumatic tires.     

The design of a hold-off device to improve the lateral comfort of rail vehicles

ABSTRACT

Rail vehicles negotiating curves or in crosswinds are subjected to high lateral forces which provoke high displacements of the lateral suspension. As these displacements need to be limited due to gauging restrictions these forces cause the lateral suspension to reach the bumpstops and consequently the passenger comfort is significantly jeopardized. The paper presents the design of a pneumatic system that allows limiting the lateral displacement during curve negotiation (hold-off device). It describes the different phases of the design process starting from the definition of requirements to be fulfilled. The main components and the effect of their characteristics on the overall performance of the centring system are studied, and completed with an experimental analysis of the centring system. Finally, the described methodology is applied to a typical high speed rail vehicle. The results prove that the concept of a centring system which uses the same technology and components that are used in rail vehicles for the pneumatic height control system of secondary suspensions is possible. This fact is particularly interesting as the market offers this kind of components and has proven their reliability during many hours of service therefore the new hold-off system will be based on in-service validated components.     

The Static Stability of Articulated Commercial Vehicles

SUMMARY

This review of the state of the art emphasizes recent results that have been obtained in extending conventionalanalysis techniques to the treatment of “Highway Trains”, that is, to heavy trucks that have multiple articulation points and employ suspensions with multiple axles. Equations of motion applicable to the equilibrium turning performances of articulated vehicles are examined with respect to using analysis techniques involving steering gains, understeer gradients, effective wheel-bases, handling diagrams, and critical speeds. These examinations provide the basis for in sights into simplified approaches for understanding the steady turning mechanics of articulated, multi-axle vehicles riding on pneumatic tires.     

Pneumatic train brake simulation method

The design of new pneumatic brakes for rail vehicles or improvements of existing ones can be made better or more efficient by the use of a simulation method. This paper gives a general presentation of the author’s modelling methods used for solving problems relating to railway pneumatic brakes. The brake models in this paper (slightly different from those of other authors) take into account air-wave phenomena including air viscosity, the influence of the brake pipe branches, heat transfer in the brake pipes and reservoirs, air flows in the brake valves and the dynamics of moving mechanical parts. For various simulation purposes, separate partial models with different levels of accuracy were created. Various verifications and identifications of the models were performed with the use of train brake testing facilities, including both in-house and other test stands. A variety of examples of simulation results are presented here.     

基于双模式执行器的商用车自适应巡航控制系统

为实现商用车自适应巡航控制(ACC)系统的功能,开发了双模式制动执行装置和电子油门控制装置,即基于高速开关阀的商用车气压电控辅助制动系统和双模式油门控制系统,可以实现驾驶员和ACC系统的协同切换控制。在此基础上,以某商用车为对象,设计了ACC系统,结合比例-积分控制器和Smith预估补偿器设计了ACC的下位控制算法。结果表明:该ACC系统速度稳态跟踪误差小于1 m.s-1,距离稳态跟踪误差小于1.5 m;同时油门执行器和制动执行器具有安装方便、与原车电子油门及气压制动系统兼容性好的优点。     

汽车主观评价综合评分方法研究

本文以各项主观评价项目评分值为依据,运用模糊聚类分析的方法得到反映各"样本车型"与"目标车辆"(各项主观评价分值最优的车辆,下同)的"接近程度"的排序情况,依据此排序结果,构造"样本车型"的综合评价评分值并通过训练得到相应的BP神经网络结构.当输入车辆各项评价项目评分值后,该BP神经网络结构能够按照车辆与"目标车辆"的...