汽车消声器声学特性的数值分析与结构改进

利用Sysnoise软件对一汽车消声器进行声场计算,得到消声器的声压分布和传递损失曲线;对消声器结构进行改进,在其内部增设一块隔板和两个穿孔管,并对改进结构进行数值计算。结果表明：低频时声波以平面波的形式向前传播,高频时声波主要以高次谐波的形式向前传播。与原始消声器相比,在600-1 200 Hz的中低频段,以及1 700-1 800 Hz,2 700-2 800 Hz的中高频段,改进消声器的传递损失提高20 dB以上;且在20-3 000 Hz总频段,改进消声器的传递损失平均提高19.8 dB。故改进消声器的消声效果良好。     

汽车发动机排气门失效分析

通过宏观检验、化学成分分析、金相检验和能谱分析等方法对汽车发动机排气门失效的原因进行了分析。结果表明:排气门没有进行固溶处理是其失效的主要原因,接触不良等是其失效的次要原因。据此提出了采取固溶和时效处理以及提高装配密封性的措施。     

483Q发动机用TiAl基合金排气阀门的研制

利用真空感应凝壳熔炼设备熔铸了 Ti Al合金 483Q发动机的排气阀门坯件 ,经热等静压及机械加工后所制得的 Ti Al合金排气阀门重量比原材质的减少了 49.3%。 483Q台架试验测试结果表明 ,Ti Al合金适宜于制造 483Q发动机排气阀门。     

Optimization of Automotive Valve Train Components with Implicit Filtering

In this paper we show how the implicit filtering algorithm can be applied to problems in parameter identification and optimization from automotive valve train design. We extend our previous work by using a more refined model of the valve train and exploiting parallelism in a different way. We apply the parameter identification results to obtain optimal profiles for camshaft lobes.     

汽车排气系统噪声数值仿真分析与结构优化

针对某型车排气尾管噪声过高问题,利用三维有限元方法对排气消声器声学性能进行分析;再应用计算流体动力学方法对消声器内部流场进行模拟计算,分析产生气流再生噪声的原因。根据分析结果对排气消声器结构进行优化。使用优化后的排气消声器进行整车排气尾管噪声测试,结果表明尾管噪声明显降低,达到设计目标值。     

汽车尾气净化催化剂的研究现状及其进展

综述了汽车尾气净化催化剂的3个组成部分－载体、活性涂层和活性组分的研究现状及其研究进展，指出了汽车尾气净化催化剂中急需解决的关键问题。     

发动机排气门锥面局部出现麻坑的原因

采用宏观和微观检验、化学成分分析和硬度测试等方法对发动机锥面局部有麻坑的发动机排气门进行了分析。结果表明：因摇臂与排气门杆部端面接触点不恰当导致气门不旋转,造成排气门杆部偏磨和排气门锥面局部漏气,最终使排气门锥面局部出现麻坑。     

汽车发动机粉末冶金排气阀座正交设计

排气阀座是汽车发动机中的重要零件,工作条件非常恶劣.采用正交试验法对材料配方进行优选,优选配方为Fe-Cr3.5-Mol.0-Cu5.0-C1.3-Ni包Al2O38.0%(体积分数),金相组织为网状分布的珠光体+隐晶马氏体+粒状碳化物.试验表明,采用上述配方及工艺制造的排气阀座圈大大提高了零件的使用性能,特别是高温使用性能;因此比较适合无铅汽油发动机及其它燃料的发动机,有望用于高性能、高负荷的发动机.     

风机盘管排气阀开裂原因分析

某风机盘管排气阀仅使用3个月便发生开裂,通过对开裂的排气阀进行宏观分析、断口及能谱分析和金相检验,对排气阀开裂原因进行了分析。结果表明:排气阀开裂起源于内壁,由于内壁接触了富含硫和氯的腐蚀性介质,加之排气阀在安装时受到了较大的外力作用产生了较大内应力,两者共同作用使排气阀内壁萌生应力腐蚀裂纹,裂纹不断扩展最终穿透壁厚导致开裂。     

Inconel751合金排气门锥面烧蚀失效分析

通过宏观检验、化学成分分析、金相检验、腐蚀产物物相分析等方法对Inconel751合金排气门锥面烧蚀失效的原因进行了分析。结果表明：排气门自身材料及加工工艺符合技术要求,排气门锥面发生烧蚀失效主要是由于其燃油中硫元素含量超标、在高温下热腐蚀排气门锥面所致。     

Characteristics of Global Automotive Supply Chain

To meet the demands of rapid development of the automotive industry, a well-built supply chain system is needed urgently under the background of globalization. The implication of Global Supply Chain(GSC) is discussed at first. Then, three characteristics of global automobile supply chain such as reversibility, complexity, and synergy are analyzed, and accordingly three apocalypses related global auto supply chain are proposed.     

某汽车排气系统振动特性

建立某汽车排气系统的有限元模型,对其进行模态分析仿真,得到排气系统的前若干阶的固有频率及其振型。基于模态分析和排气系统的振动测试结果,对排气系统在发动机不同转速下的激励引起的振动进行分析,研究排气系统的振动特性,提出结构的改进意见,为提高排气系统的工作可靠性和使用寿命提供参考。     

基于排气噪声的柴油机气阀故障诊断

通过对柴油机气阀机构七种状态下的排气噪声信号建立AR模型,以AR模型的自回归参数作为故障识别的特征向量,建立基于极限学习机的柴油机气阀故障诊断模型,并与反向传播神经网络算法、径向基网络算法和基于支持向量机的诊断模型相比较。试验结果表明,排气噪声信号可用于柴油机气阀故障的诊断,且基于极限学习机的诊断模型与其他三种算法的分类正确率均可达到95 %以上,但在学习速度上,极限学习机具有明显的优势。     

基于ProCAST的制动铸件精确成形数值模拟与工艺提升

目的 针对排气制动阀铸造工艺控制不当会产生缺陷这一问题,结合模拟分析,提出合理的铸造工艺方案,以减少铸件缺陷。方法 基于ProCAST软件对蝶阀阀体铸造工艺进行模拟,研究阀体铸件在充型、凝固过程中的速度场、温度场、固相率分布和缺陷分布,并根据模拟结果对工艺进行优化。结果 添加侧冒口和冷铁后,阀体的缩松缩孔缺陷得到了有效控制,缺陷体积减少了95%以上,获得了完整铸件。结论 通过铸造模拟有效指导了排气制动用蝶阀的生产实践,优化了生产工艺,节约了生产成本。     

Interfacial Characteristics of Nanocrystalline FeMoSiB Alloys

By using X-ray diffraction (XRD), transmission electronic microscopy (TEM) and transmissionMssbauer spectroseopy (TMES), the formation, structure and properties including microhardnessand electrical resistivity of nanocrystalline FeMoSiB alloys have been investigated. By annealing theas-quenched FeMoSiB sample at 833-1023K for 1 h, nanocrystalline materials with grain sizes of15 to 200 nm were obtained. Mssbauer spectroscopy results reveal a quasi-continuous distributionfeature of P(H)-H curves for 15 nm-and 20 nm-grained samples. Also, it was found that resistivityand microhardness of nanocrystalline Fe-Mo-Si-B alloys exhibit strong grain size effect.     

摩托车排气管的振动特性研究

通过对某摩托车排气管结构进行模态分析,结果表明排气管在外界激励下可能会发生结构共振,吊挂的位置不影响结构的模态特性,提}Il减小结构共振的可靠方案;通过功率谱阵分析,表明机械共振对该摩托车噪声贡献很小.     

Structural Characteristics of Rapidly Quenched Al-Si Alloys

The structure of rapldly quenched Al-Si alloys (1 and 4 wt-%Si) was systematically studied by optical and transmission electron microscopy (TEM ) as welI as X-ray djffractjon (XRD). ExperimentaIresults show that rapid solidification refines the grain size. extends the solid solubility of Si in Al and Introduces a high density ot defects which exist in the forms of vacancies, dislocations and dislocation loops. etc.. The decomposition process of the alloys was fol lowed by using differential scanning calorimeter (DSC) and the activation energy for precipitation of Si was obtained through Kissinger analysis. The precipitation behaviour of Supersaturated Si in both samples was further examined by TEM. It was found that Si mainly precipitated inside the grains in Al-1 wt-%Si alloy. while in Al-4 wt-%Si alloy. nearly all the Si precipitates distributed along the grain boundaries. This may be due to the structure difference between the alloys in as-quenched state     

某型柴油机气门断裂原因分析

针对某型柴油机气门在运行2 000 h后发生的失效问题,对失效的气门进行宏观与微观断口、金相、材料成分、硬度等全面分析。结果表明,排气门杆部上侧为首断件,排气门下侧盘部是后断件。排气门的断裂模式为疲劳断裂,源区位于摩擦焊位置的内部。排气门发生疲劳断裂的主要原因是焊缝位置存在较大的C类夹杂物导致疲劳源的产生进而发生疲劳断裂。     

Potential Magnesium Alloys for High Temperature Die Cast Automotive Applications: A Review

Magnesium, as a lightweight construction material, has rapidly grown its applications in the automotive industry since the early 1990s. To maximize the weight reduction of vehicles by lightweight magnesium alloys in the coming years, the use of newly developed high-temperature magnesium alloys is expected to increase significantly, particularly in the powertrain applications where the creep resistance is always required. This article reviews recent developments of the creep-resistant magnesium alloys. Fundamental aspects of the creep deformation theory and mechanisms are described. The metallurgical principles for designing the creep-resistant alloys are highlighted. The creep behavior of magnesium and its conventional alloys is discussed based on some microstructure analyses. The mechanical properties, microstructure, and manufacturability of the newly developed creep-resistant magnesium alloys are also overviewed. The further research and development work is outlined in terms of developing magnesium alloys for some potential and value-added automotive applications.