基于虚拟仪器的汽车制动器制动噪声问题的研究

本文利用虚拟仪器技术,进行了汽车制动器制动噪声问题的研究,给出了汽车制动器振动噪声测量、信号分析、声源识别的测试分析方法。通过分析大量试验数据,找出了盘式制动器制动噪声产生的原因,为该制动器的优化设计提供了依据。     

摩擦制动低频振动噪声的研究现状

通过分析总结过去几十年的研究文献,从试验研究和理论研究两方面来详细介绍汽车摩擦制动引起的低频振动噪声的国内外研究现状,其中重点介绍了制动颤振和制动抖动两种低频制动噪声和振动的产生机理、理论建模和实验研究工作。最后,对有效解决摩擦制动产生的低频振动和噪声的技术和方法进行了展望并提出建议。     

轿车制动引起方向盘抖振分析与控制技术研究

随着我国汽车工业突飞猛进的发展,在2009年的产量就突破了千万量。汽车不断的走进千家万户,成为人们代步的工具。这当然会使得人们对汽车的舒适性能提出更高的要求。而汽车舒适性的主要影响因素是振动和噪声等问题。长期以来许多汽车生产厂商致力研究振动噪声问题。轿车制动时导致汽车方向盘抖动会严重影响驾驶员的舒适性,也使得驾驶员会更加容易疲劳,所以研究轿车制动引起方向盘抖振分析与控制技术很有必要。     

基于风险矩阵法的汽车制动系统缺陷风险评价研究

汽车制动系统缺陷严重影响汽车的行驶安全,是汽车召回的重要原因之一.为提高汽车召回效率,本文分析了近几年汽车制动系统缺陷引发召回的情况,梳理提出了汽车制动系统缺陷引发交通事故的危害分级以及引发事故的概率分级,并以风险等级为依据,提出了一种汽车制动系统缺陷风险评估程序.结合我国汽车召回真实案例,进行风险评估程序可行性研究,结果表明:风险矩阵法可以准确的识别汽车制动系统缺陷,因此,风险矩阵法能指导汽车制动系统缺陷的风险评估和汽车召回,也可扩展到汽车其他缺陷的召回工作.     

某SUV盘式制动器低频颤鸣测试分析与工程实践

汽车制动噪声是影响车辆驾乘舒适性的重要因素,而制动低频颤鸣问题常常发在低速行驶的工况,由于环境背景噪声较小,容易被市场用户投诉与抱怨,因针对该问题的工程改善方案涉及较多控制因素及相关零部件,所以一直是汽车制动舒适性开发的重点与难点。以某SUV(Sport Utility Vehicle)车型蠕行颤鸣问题的测试排查分析过程为例,系统地阐述制动颤鸣现象发生的原理,给出工程控制的措施,提出轮辋法兰安装面与车轮螺栓预紧方式是控制制动低频噪声的关键因素之一,并通过制动盘安装连接方式的优化,实车验证了改进方案的有效性,这对于提升制动NVH(Noise Vibration Harshness)性能工程开发具有较重要的借鉴与指导意义。     

浅谈汽车在制动性能测试过程中出现的问题及原因分析

制动系统是汽车的一个重要组成部分,对汽车行驶安全起着重要的作用.在汽车的使用中,制动系统各部分零件的磨损、变形、断裂及维护调整不当,都会导致制动失灵、制动跑偏、制动效率下降等故障,从而影响行车安全,导致交通事故的发生.因此检测汽车的制动性能是汽车安全性能检测的一项基本且重要的内容.     

电动汽车可变能量回收制动方案的设计

电动汽车在运行过程中最大问题是电能补及和电池使用时间.汽车机械制动足将动能转换为热能消耗,电动汽车制动能量回收是通过发电装置将汽车制动时的动能转换为电能,对蓄电池进行充电,从而延长电动汽车行驶里程.通过对汽车制动模式的分析,通过改变发电机励磁电流人小,控制发电机发电量,利用磁阻力矩产生不同的汽车制动力矩.     

某SUV盘式制动器低频颤鸣测试分析与工程实践

汽车制动噪声是影响车辆驾乘舒适性的重要因素，而制动低频颤鸣问题常常发在低速行驶的工况，由于环境背景噪声较小，容易被市场用户投诉与抱怨，因针对该问题的工程改善方案涉及较多控制因素及相关零部件，所以一直是汽车制动舒适性开发的重点与难点。以某SUV(Sport Utility Vehicle)车型蠕行颤鸣问题的测试排查分析过程为例，系统地阐述制动颤鸣现象发生的原理，给出工程控制的措施，提出轮辋法兰安装面与车轮螺栓预紧方式是控制制动低频噪声的关键因素之一，并通过制动盘安装连接方式的优化，实车验证了改进方案的有效性，这对于提升制动NVH(Noise Vibration Harshness)性能工程开发具有较重要的借鉴与指导意义。     

汽车车内制动噪声主动控制

部分汽车制动时的车内噪声以低频成分占主导。低频噪声能量大,车内较强的低频制动噪声会给乘员带来不舒适的乘坐感受,降低车辆的乘坐舒适性。采集三辆轿车车内60 km/h紧急制动时司机位双耳处噪声信号并进行时-频域分析,分析结果与实车试验乘坐感受一致,接着运用低频噪声消噪效果较好的主动噪声控制方法,结合自适应LMS算法对样本信号进行消噪仿真实验,制动噪声低频部分得到较大的抑制,特别是在20 Hz~50 Hz低频带内,噪声能量衰减明显。     

汽车制动检测系统设计

随着汽车逐渐在人们生活中普及,汽车给人们带来方便的同时也带来了不少交通安全问题,而这些交通安全问题主要是由于汽车的制动出现故障所导致的。因此人们越来越重视汽车的制动检测。文章主要介绍汽车制动性能检测意义、汽车制动性能检测发展状况和汽车制动性能检测技术指标,最后设计一套汽车制动性能的检测机构。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。