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关键词： 学习领域课程   学习任务   行动导向   工作过程知识  

摘要： 与传统教学不同,以工作过程系统化为导向的学习任务在教学内容、教学组织、职业能力培养、学习评价反馈等方面存在着较大差异。为此,文中以自动变速器离合器的检修为例演示了工作过程系统化的学习领域课程的学习任务设计和实施,并探讨了实施过程中所遇问题的解决方案。

关键词： 湿式离合器   短暂接合   热点生成   机理  

摘要： 为了解决湿式多盘离合器摩擦副短暂接合过程中热点生成现象,在考虑摩擦副滑动速度、波长、接触压力增长率与迁移速度、热点数之间的对应关系,建立热点生成理论的数值和有限元模型对热点产生机理问题进行规律性研究,研究表明:湿式制动器短暂接合过程中的高速滑动速度是造成严重热点现象的主要原因,滑动速度增加,增长率与临界速度也增加,对应产生的热点数越多,最大增长率对应的波长则向较小的方向移动;弹性模量越小,相同滑动速度对应下的增长率与迁移速度越小,热点生成个数也下降,临界速度提高;增加摩擦材料厚度可以显著降低增长率,但增加了最不稳定状态下的波长,增加摩擦材料厚度可以显著增加临界速度;有限元部分针对不同摩擦材料和摩擦副不同几何参数揭示了材料弹性特征和几何尺寸对热点产生的影响。

关键词： 车辆工程   离合器   压盘   温度场   应力场  

摘要： 在多重应力的作用下,压盘易发生失效。利用Pro/E建模,综合运用Hypermesh,***等有限元分析软件,完成对轿车标准起步工况下离合器压盘受热、受力模型的分析,得到起步工况下压盘温度场、应力场随半径及时间变化的趋势和规律。研究表明:不同工况下温度场与应力场的分布有一定的相似性,但应力场相对于温度场有一定的滞后性。

关键词： 离合器   卡簧   失效分析   硬度  

摘要： 为确定离合器分离轴承座卡簧断裂的原因,采用断口分析、金相检验及硬度检测等方法,对断裂卡簧进行分析。结果表明,断裂卡簧硬度高,不符合技术要求。卡簧第二弯角角度尺寸不符合要求,该处形状不良,使得卡簧第一弯角对分离轴承座导套座槽底产生附加正应力,最终导致卡簧发生疲劳断裂,并在分离轴承座导套座槽底产生磨损。

关键词： Dual clutch transmission   Shifting map   Gearshift pattern   Modeling and simulation   Fuel economy   Performance  

摘要： Owing to ever more stringent regulations and customers' expectations, auto manufacturers have been considering numerous technology options to improve vehicle fuel economy. One of these is transmission technology, which has been shown to be one of the most cost-effective technologies. Over the past few years, transmissions have significantly evolved and have impacted both performance and fuel efficiency. As one of the advanced tranmissions, the dual clutch transmission (DCT) is the first automatic transmission to provide better efficiency than manual transmissions. DCTs provide reduced shift shocks and better driver comfort in addition to higher top speeds and torques. In this paper, a model and shifting controller for the DCT are developed in the vehicle systems context using Autonomie, a model-based vehicle simulation tool. Finally, the Autonomie DCT model and control strategy are validated using vehicle test data from Argonne's Advanced Powertrain Research Facility.

关键词： Maternal antibodies   Yolk testosterone   Egg composition   Parasites   Maternal effects   KITTIWAKE RISSA-TRIDACTYLA   IMMUNE FUNCTION   COLONIAL SEABIRD   GREAT TITS   AVIAN EGGS   ECTOPARASITE   TESTOSTERONE   ANTIBODIES   DEPOSITION   PARASITE  

摘要： Egg components are important mediators of prenatal maternal effects in birds and other oviparous species. Because different egg components can have opposite effects on offspring phenotype, selection is expected to favour their mutual adjustment, resulting in a significant covariation between egg components within and/or among clutches. Here we tested for such correlations between maternally derived yolk immunoglobulins and yolk androgens in great tit (Parus major) eggs using a multivariate mixed-model approach. We found no association between yolk immunoglobulins and yolk androgens within clutches, indicating that within clutches the two egg components are deposited independently. Across clutches, however, there was a significant negative relationship between yolk immunoglobulins and yolk androgens, suggesting that selection has co-adjusted their deposition. Furthermore, an experimental manipulation of ectoparasite load affected patterns of covariance among egg components. Yolk immunoglobulins are known to play an important role in nestling immune defence shortly after hatching, whereas yolk androgens, although having growth-enhancing effects under many environmental conditions, can be immunosuppressive. We therefore speculate that variation in the risk of parasitism may play an important role in shaping optimal egg composition and may lead to the observed pattern of yolk immunoglobulin and yolk androgen deposition across clutches. More generally, our case study exemplifies how multivariate mixed-model methodology presents a flexible tool to not only quantify, but also test patterns of (co)variation across different organisational levels and environments, allowing for powerful hypothesis testing in ecophysiology.

关键词： 离合器   膜片弹簧   加权系数   matlab   优化设计  

摘要： 膜片弹簧是汽车离合器的重要部件,是由弹簧钢板冲压而成,形状呈碟形。膜片弹簧结构紧凑且具有非线性特性,高速性能好,工作稳定,踏板操作轻便,因此得到广泛使用。本文通过对膜片弹簧建立数学模型,特别通过引入加权系数同时对两个目标函数进行比例调节,并用matlab编程来优化设计参数。通过举例,结果证明在压紧力稳定性,分离力及结构尺寸上优化结果较为理想。

关键词： 全自动洗衣机   离合器   故障维修   结构   脱水过程   状态切换   紧急制动   减速器  

摘要： 离合器又称减速器，是全自动洗衣机的主要传动及减速部件．其主要作j刳是完成洗衣机的洗涤与脱水状态切换，并能完成脱水过程中的紧急制动等动作。

关键词： 有限元   模态计算   ANSYS   离合器摩擦片  

摘要： 文章建立某重型汽车离合器摩擦片有限元模型,确定载荷及边界条件,运用ANSYS软件中的Lanczos算法进行模态计算,求得重型汽车离合器摩擦片的前几阶固有频率和振型,从而为其设计的改善提出建议。

关键词： 自动张紧带传动   齿轮传动   参数匹配   程序设计  

摘要： 介绍自动张紧带传动-齿轮传动组合的传动过程,进行受力分析,建立了带传动自动张紧时摆杆的受力平衡方程,推导出小齿轮直径与大带轮直径在保证带传动既不打滑又不疲劳时的合理匹配关系式。针对该种组合传动需同时满足带传动自动张紧条件和齿轮传动强度条件的要求,提出有效的计算机程序设计方法。最后,给出设计实例。