对异步电动机制动方式的研究

异步电动机的制动方式对保证人身及设备安全有着非常重要的意义。文中介绍了几种常用的制动方式的特点,对不同制动方式进行了技术比较,分析了他们各自的实用场所,为实际应用提供了科学的理论依据,具有一定的实用价值。     

制动管路尺寸对制动系统性能影响的研究

车辆制动系统是汽车安全行驶的重要保障。常规制动系统开发主要针对制动器、制动液压缸、驻车机构等部件的设计计算,往往忽略连接各个液压元件的制动管路尺寸对车辆制动性能的影响。经过研究与实践发现,制动管路的尺寸直接影响制动响应时间与释放时间。其中,制动响应时间过长会增加车辆在紧急工况下的动作时间,是车辆制动系统的主要缺陷之一,而制动释放时间直接影响车辆的驱动效率。为了量化制动管路尺寸对车辆制动性能的影响,文章以HCU性能测试台架为测试平台,首先在AMESim环境下对制动系统建模,模拟不同尺寸的制动管路在相同制动系统和制动信号下的管路压力响应,筛选最优制动管路尺寸区间。最后在HCU性能试验台架上更换三个仿真结果相近的制动管路验证仿真结果,并选出尺寸最优的制动管路,优化台架的制动性能。文章介绍的方法对消除制动系统缺陷与车辆制动系统设计过程中制动管路选型都具有重要意义。     

恒压排气制动蝶阀的结构及应用简析

排气制动蝶阀作为一种无衰退的辅助制动系统,由于其结构简单,性能可靠,在使用柴油发动机的载重汽车及客车上得到了广泛的应用.但由于传统排气制动蝶阀的缺陷,又限制了它的进一步发展.而恒背压排气制动蝶阀则克服了传统排气制动蝶阀的缺陷,能最大限度的提高整车的制动功率.另外恒背压排气制动蝶阀还可以与其他类型的辅助制动器联合使用,以...     

汽车电子机械制动执行机构的设计分析

EMB(Electro-mechanical brake)是真正意义上的线控制动,完全摒弃了制动液,可实现与整车ABS、TCS、ESP、EBA等功能集成。提出了一种新的电动执行机构的方案,其相对电子机械制动器在传动装置组成部件和结构支撑方面得到了优化,同时增加了自锁功能,本结构设计可有效提高机构响应速率、简化驻车控制逻辑、提升机构使用寿命。     

一种新型的制动电机

一种新型的制动电机山东省东成机电一体化研究所（２５００１１）郭健宋德增李世恩ＹＥＪＳ系列干式多片失电式电磁制动电机（以下简称制电机）研制成功，并已获国家实用新型专利，专利号为９５２３４５４２０。１产品的由来一般电机无制动装置，如采用“刹车”提高效率...     

CPCD80C叉车制动性能的改进

CPCD80C～CPCD100Q系列叉车在使用中普遍存在制动性能差的问题，表现在制动踏板力大、制动距离长、轮胎不拖印等情况，影响了叉车的安全性能。该车的制动系统采用真空增压技术，通过真空增压器将制动液加压后作用在制动分泵上，通过分泵顶杆推动制动蹄向外张开，压紧制动鼓实现制动。在制动结构型式和尺寸及摩擦材料一定的情况下，制动力的大小取决于蹄片的张力，而蹄片张力的大小与活塞的油压和面积大小成正比。在制动器尺寸不变的情况下，加大活塞直径和油压可以提高蹄片的张力，使摩擦力增大，从而提高制动效果。     

变反接制动为能耗制动

变反接制动为能耗制动贵州省粮食机械厂杨晓东我单位有几台机加工设备为反接制动式的，通过对其长期观察，发现有以下几个问题：①反接制动瞬时电流大，瞬时电流冲击接近达到起动电流的２倍；②对设备的影响，其结果造成起动时机械运行冲击增大，产生的负作用使该设备的加...     

广州地铁APM列车制动机理分析

根据广州市珠江新城旅客自动运输系统(APM)列车的运行特点,介绍APM列车制动系统的制动方式及其特点,分析APM列车动态制动和摩擦制动的工作机理及其区别和联系,阐明APM列车制动系统的电控制过程和气控制过程,从而为APM列车制动系统的维护和管理提供一定的依据.     

汽车发动机压缩辅助制动性能分析

汽车发动机辅助制动装置主要负责车辆减速控制,其发展历史悠久,由排气蝶阀制动到泄气式制动,直到当前应用广泛普遍的压缩释放制动。在结构创新与技术发展形势下,发动机制动性能也在不断优化。由于体积较小,不需车辆改动,而且我国对重载车辆载重限制与处罚力度一直在不断加大,发动机辅助制动特别是压缩释放制动在激烈的市场竞争中脱颖而出,成功发展成了汽车标配。在此基础上,本文对汽车发动机压缩辅助制动性能进行了详细分析。     

CAE分析在客车盘式制动器NVH领域的应用

本文对制动噪声、制动抖动等盘式制动器常见的NVH故障现象及产生机理、影响因素、预防措施等进行研究,根据机理提出利用CAE分析在设计阶段对相关零部件进行确认,避免因零部件共振出现制动NVH问题,最后通过设计开发验证实例证明CAE分析改进方法的有效性。     

A review of the fundamental concepts of measurement

The paper surveys the current state of the theory of the fundamental concepts of measurement which is based on the model theory of logic. A brief review is given of the historical development of measurement theory. The model-theoretic definition of measurement is presented, together with a discussion of representation and uniqueness conditions. Nominal, ordinal, extensive and interval measurement structures are outlined. The classification of scale types and the problem of meaningfulness are considered. A survey is given of conjoint and derived measurement. A brief review is made of the applications of measurement theory. Consideration is given to the treatment of uncertainty. The setting-up of systems of scales of measurement for a domain of science and its relation to theories for that domain are discussed. It is argued that measurement as defined is related to other forms of symbolic representation such as is involved in computer data representation and natural language.     

Distribution curves of sectional areas through some families of convex particles

We outline the results of a computer program which calculates frequency distributions of functions of cross-sectional regions of convex planar-faced polyhedra, ‘sphero-polyhedra’, and populations of perturbed polyhedra. This is done by ‘cutting’ a computer representation of the figure by a large number of random planes. The procedure is applied to cubes, dodecahedra, truncated octahedra, and approximate β-tetrakaidecahedra. Certain aspects of the shape of the object, e.g. sharpness of corners, angularity, compactness, and degree of symmetry are related to aspects of the shape of the distribution curves, e.g. beginning and ending points of the curves, rate of rise of the peak, relative location of the peak, and height and width of the peak.     

高速动车组减振器载荷特征研究

减振器的主要功能是提供阻尼力以衰减和抑制车辆系统振动,对高速动车组动力性能有十分重要的影响。既有研究主要将减振器处理为阻尼力以研究车辆系统动力性能,极少从动力学和结构可靠性角度关注减振器自身承受的载荷。制作某型高速动车组转向架抗蛇行减振器、轴箱减振器、二系横向和垂向减振器测力元件,在大同-西安高速线路上测试并获得该型动车组运行过程中四种减振器载荷引起的应变信号。对测试数据进行处理和分析,获得高速动车组运行工况下四种减振器载荷的时间历程,分析减振器载荷的时域和频域特征。采用雨流计数法统计减振器载荷峰谷值和频次,获得不同速度等级下载荷分布。结果表明,高速动车组抗蛇行减振器载荷最大、二系横向减振器载荷最小。轴箱减振器相对速度最大、二系横向减振器相对速度最小。减振器载荷总体上呈正态分布,而且一般有列车运行速度越高减振器载荷越大。列车正线行驶时曲线半径对轴箱减振器、二系垂向减振器以及二系横向减振器载荷影响不明显,列车速度和线路小半径曲线对抗蛇行减振器载荷影响明显。     

混合驱动机构研究进展与发展趋势

混合驱动机构是可控机构的一种,其适度柔性以及降低驱动与控制成本的特性与优势使其成为现代机构学的重要研究分支之一。随着对混合驱动机构研究的深入,混合驱动机构理论和应用也不断地发展和创新。对现有的研究成果加以分析和总结将有利于促进混合驱动机构理论和应用的进一步发展。分析混合驱动机构的内涵,分别论述双自由度和多自由度混合驱动机构的研究进展,主要包括:混合驱动机构的构型设计与可动性、混合驱动机构的轨迹特征、混合驱动机构的运动学、混合驱动机构的动力学及混合驱动机构的应用等方面的研究进展。提出混合驱动机构研究的关键问题,总结了混合驱动机构的未来发展趋势。研究成果对拓展混合驱动机构的设计空间、开辟混合驱动机构新的应用领域具有重要意义。     

机械结构液体层厚度超声谐振的测量方法

针对机械结构安全运行的需要,进行机械结构液体层厚度超声谐振测量方法研究。基于垂直入射纵波在三层介质中传播的连续模型,通过对不同厚度液体层超声反射系数分析,提出一种基于超声反射系数谐振频率的液体层厚度测量方法。在对超声谐振测量系统进行标定的基础上,进行机械结构液体层厚度超声谐振测量试验研究,同时研究了3层介质的声学特性对液体层超声反射系数及厚度测量的影响。结果表明,液体层反射系数的谐振频率能够表征其厚度。在对测量系统进行标定的基础上,测量误差基本保持在5%以内。液体层两侧介质材料的变化对液体层的测量基本没有影响,但液体层介质材料的变化将对测量系统产生影响,需要重新对测量系统进行标定。     

Evaluating the Wear in Steel-Steel and Iron-Iron Friction Pairs by the Eddy-Current Method

Results of a study of steel-steel and iron-iron friction pairs by eddy-current and X-ray methods are reported. An eddy-current transducer is shown to yield a generalized characteristic of changes in the properties of a surface layer in the process of its wearing. Similar results are obtained by the X-ray investigation of the same layer. A correlation between readings of an eddy-current device and the magnitude of the linear wear in the contact zone of tribological coupling is shown to exist at the stage of steady-state and intensive wear.__________Translated from Defektoskopiya, Vol. 41, No. 4, 2005, pp. 17–24.Original Russian Text Copyright © 2005 by Gorkunov, Kharlamov, Kogan, Zadvorkin.Dedicated to the 100th Anniversary of the Birthday of Corresponding Member of the Russian Academy of Sciences M. N. Mikheev     

纳米CeO2/Zn-4.5Al-RE复合材料的力学性能及表观粘度

测试了不同增强颗粒质量分数的纳米CeO2/Zn-4.5Al-RE复合材料的力学性能,测定了柱形试样熔化前后的高度变化率,讨论了复合材料的表观粘度,并研究了纳米CeO2含量对两者的影响规律.结果表明:CeO2的加入提高了基体的力学性能,当其含量为3%时,复合材料的维氏硬度、弹性模量和抗拉强度分别达到96.7 HV,17.1 GPa和176.5 MPa,较基体分别提高了41.2%,34.6%和34.2%,而伸长率则降低了4.6%;随着CeO2含量的增加,复合材料的高度变化率△H/H0大大降低,粘度急剧增大.     

Effect of manufacturing and assembly defects on two-stage gear systems vibration

The modeling of the dynamic behavior of a two-stage gear system is made for a general configuration of wheels location. The excitation is induced by the periodic variation of the mesh stiffness. This case describes the real working of the gearings. The variation of the mesh phasing is related to the number of teeth and also to the wheels location. We developed a plane model of a two-stage gear system. The modal analysis of the system was then treated. The calculation of the dynamic response was done by a step-by-step time integration method (Newmark algorithm). Three cases of wheels location are treated. The solutions are presented both in the frequency domain and in the time domain. Three types of geometric defects of the toothed wheels are introduced in the model: defect of eccentricity, profile error and assembly defect. An analysis of the effects of these defects on the gear system dynamic behavior is then treated.     

Development of standard reference materials for air quality measurement.

The National Bureau of Standards is engaged in a continuing program involving gaseous Standard Reference Materials for air pollution measurements. Preparation of such materials requires definition of the stability, homogeneity, and accuracy of the samples. This information is obtained by long term studies of the gas systems, by development of absolute methods of analysis, and by analysis of large numbers of samples prepared in bulk. The results of studies, extending over several years, of low concentration of carbon monoxide in nitrogen and nitric oxide in nitrogen are reported. Over one thousand samples of these materials have been analyzed and the stability with time and the within-batch homogeneity have been characterized. Accuracy is achieved by use of gravimetric standards and with dynamic dilution systems. Accuracy attainable by either method is described. The use of permeation tubes of sulfur dioxide and nitrogen dioxide is necessary in some situations because of the reactivity of the gases. Data covering the stability and accuracy of these devices has been collected over a period of several years.     

并联机器人连杆的安全行程分析

针对并联机器人存在的运动失控、铰链约束、连杆干涉等不安全因素,讨论了连杆的安全行程问题.找出了6自由度并联机器人的16种不同极限状态.通过位置反解迭代求解位置正解,并且综合考虑铰链转角约束和连杆干涉约束的方法,建立了机构的安全检验算法.然后采用二分逼近法求取连杆的安全行程.通过实例得到了机构结构参数与安全行程的关系.