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关键词： 瞬态动力学   离合器   沟槽   振动加速度   应力  

摘要： 基于瞬态动力学原理,利用有限元软件ABAQUS中的显式动力学方法,建立了摩擦离合器系统的有限元模型,研究摩擦离合器在接合过程中的振动加速度信号及应力场分布,并用试验进行验证。结合相关仿生学设计,设计了3种有沟槽的制动闸片,分析沟槽对接合特性的影响。最后分析了沟槽的布置模式及斜置沟槽对接触振动的影响。结果发现:离合器在接合过程中,振动加速度信号出现剧烈变化并逐渐消失,仿真结果符合试验结果;复合沟槽表面能有效地抑制接触振动,径向沟槽表面次之,而环形沟槽闸片不能抑制接触振动;单一摩擦盘上沟槽抑制接触振动的效果没有双侧摩擦盘上沟槽的抑制效果好。斜置沟槽离合器片在接合时的振动幅值低于径向沟槽而高于复合沟槽。

关键词： 汽车底盘   故障诊断   离合器  

摘要： 我国汽车保有量连年上升,而汽车故障也越来越成为了众多车主与维修部门不可回避的问题。为此,文章将对汽车底盘制动系统故障展开分析,针对机动车离合器常见故障分析和维修要点、转向沉重问题的故障成因以及解决办法、制动踏板较低问题的故障成因以及解决办法、制动跑偏问题的故障成因以及解决办法四个角度进行探讨,为今后的汽车底盘制动系统维护提供参考。

关键词： 电动汽车   离合器   可变怠速起步   控制策略  

摘要： 电动汽车行业的快速发展，推动了与之相关的驱动电机、控制器、整车驱动方案与能源管理等关键技术的不断完善。就电动车辆驱动方式而言，轮毂驱动具有简约的传动链、灵活的动力配置以及更为高效的整车动力性等特点，其被认为是未来电动汽车一种极具发展前景的驱动模式。平稳、快速的启停控制一直是电动汽车传动系统的研究重点与难点。然而，轮毂电机与车轮间通常采用刚性紧固连接的方式，在应对复杂的路面条件以及频繁的启停操作时，常规的直接起步策略易造成较长的冲击电流滞留时间以及较大加速度变化引起的起步冲击感，车辆起步品质并不理想。为此，借鉴普通燃油汽车发动机点火启动，怠速起步与离合换挡的思想，本文将离合器引入整车传动系中，用于实现车辆与轮毂电机可控柔性耦合的启停过程。基于此，本文尝试“电机空载启动+变怠速切换+机电分离制动”新型驱动方案，并开展最优变怠速起步规律的探讨，为轮毂电机电磁离合装置与系统的实验研究提供技术支撑。\n 结合汽车动力学相关知识，本文首先建立车辆动力学模型，在此基础上分析车辆遇到车轮下陷、轴承摩擦等因素下，车辆起步较为困难的原因，由此阐述轮驱式电动车引入离合器的必要性。而后，基于一种新型电磁离合单元的轮毂电机离合系统，分析其工作特点，本文将驱动电机与车轮通过离合器快速啮合的动作等效为非弹性碰撞的过程，即用一种理想离合器模型来处理在不同转速差情况下进行电机与车轮的接合过程。\n 接下来，为量化电动车辆起步过程中受到的电磁与机械冲击，本文以加加速度、峰值电流、加速时间和车辆起步过程中的电枢发热效应，即从机、电、磁、热四个方面综合评价车辆起步性能。结合前述车辆动力学模型，推导电机与车轮紧固连接直接起步时，起步性能指标与电机电枢电压的关系，分析车辆直接起步难以兼顾良好的起步舒适感与快速起步过程的原因。在此基础上，进而对车辆直接起步进行仿真研究，并与实施柔性耦合的离合起步相比，由此论证离合起步方案在缓释电动车辆起步过程中机电冲击方面的积极作用。进一步，本文构建电动汽车传动系统可变怠速起步的综合实验台架，模拟车辆在受冲击型负载的情况下，有、无离合器作用的起步过程和受控行为；并对实验台架相关时间常数进行测量和优化估计，为车辆用变怠速起步控制方案的规律研究奠定基础。\n 普通燃油汽车受到单一稳定怠速限制，起步能力被限定，舒适感亦只能为平均值。轮毂驱动电机具有优良的无级变速品质，可根据实际路况或载荷需求，灵活选取离合器切入车轮怠速，起步性能将可能大幅提升。结合一种理想离合器模型与车辆动力学模型，本文重点分析变怠速起步与车辆起步性能之间的关系，推导离合器接合过程中电枢电流轨迹曲线和离合器啮合时刻的加速度变化值；并以平衡离合器啮合时刻的牵入转矩需求与较小的车辆加加速度为目标，优化离合器切入怠速，得到基于负载反馈-怠速调整的优化控制规律；继而，辅以基于Pontryagin极小值原理优化的牵引控制思想，得出车辆加速至期望车速过程中电枢电流轨迹与车速轨迹的控制规律，以实现车辆加速过程中电枢损耗最小化控制，进一步提升起步过程中能源利用率。\n 此外，由于离合器快速切入车轮的瞬时加加速度随怠速上升而线性增加，故从舒适性考虑，驱动电机切入车轮的怠速存在上限。为进一步拓展离合起步的负载能力，本文提出一种自动补偿电压的变怠速起步新方案。并在此基础上，分析电枢电压轨迹与车辆起步性能指标之间的关系，基于两点优化策略的思想，以协调车辆起步过程中加加速度与牵入转矩为目标，得出离合器进行接合时电枢电压轨迹的控制规律。

关键词： 干式离合器   防爆离合器   防爆柴油机无轨胶轮车   阻火器  

摘要： 分析了防爆离合器的结构特点,对防爆离合器防爆型式进行了深入研究,并对防爆离合器的应用情况进行了分析。结果表明:防爆离合器性能稳定,安全可靠,是煤矿井下机械传动车辆中主要的扭矩传递元件。

关键词： 液压操纵式离合器   诊断   问诊   故障成因  

摘要： 本文介绍了汽车液压操纵式离合器常见故障产生的原因和故障诊断的常用方法,通过引用两起汽车离合器故障案例重点突出问诊和经验诊断等方法,汽车维修技术人员应在工作中不断的学习和总结分析,才能将文中重点介绍的问诊法和直观诊断法使用的得心应手。

关键词： shape-memory alloys   wires   rotary minimotor   overrunning clutches   ACTUATORS  

摘要： An attractive but little explored field of application of the shape-memory technology is the area of rotary actuators, in particular for generating endless motion. This paper presents a miniature rotary motor based on shape-memory alloy (SMA) wires and overrunning clutches, which produces high output torque and unlimited rotation. The concept features an SMA wire tightly wound around a low-friction cylindrical drum to convert wire strains into large rotations within a compact package. The seesaw motion of the drum ensuing from repeated contraction-elongation cycles of the wire is converted into unidirectional motion of the output shaft by an overrunning clutch fitted between drum and shaft. Following a design process developed in a former paper, a six-stage prototype with size envelope of 48 x 22 x 30mm is built and tested. Diverse supply strategies are implemented to optimize either the output torque or the speed regularity of the motor with the following results: maximum torque = 20 Nmm; specific torque = 6.31 x 10(-4) Nmm/mm(3); rotation per module = 15 deg/cycle; and free continuous speed = 4.4 rpm.

关键词： ACCESS to information   PARADIGMS (Social sciences)   CHANGE (Psychology)   PSYCHOLOGICAL aspects  

摘要： The article discusses the role access to information plays in leading to paradigm shifts, or changes, in understanding, including professional baseball executive Branch Rickey. It references the book 'Ahead of the Curve,' by Brian Kenny, including the book's discussion of group psychology and belief in propositions.

关键词： facultative multiple breeding   lizard   mate availability   polygamy   sperm storage   Zootoca vivipara   LIZARD LACERTA-VIVIPARA   SEX-RATIO   REPRODUCTIVE INVESTMENT   BODY-SIZE   FEMALES   DENSITY   TEMPERATURE   POPULATIONS   COMPETITION   PLASTICITY  

摘要： Females of many iteroparous species face trade-offs between producing one or multiple broods per reproductive season, and over fertilizing broods with sperm from the same or different mates. Both trade-offs might be affected by the availability of males (i.e. absence/presence of males) and the timing and duration of male encounters. Here, we experimentally manipulated the duration of mate availability at the first brood and mate availability per se (i.e. absence/presence of mates) at the second brood, and tested their effects on female and male reproductive success, using the common lizard, Zootoca vivipara, as a model species. Females were either exposed to males for a long period before their first annual reproduction and they could remate before their second annual reproduction (unrestricted treatment), or they were exposed to males for a short period before their first annual reproduction and were not allowed to remate (restricted treatment). Reproductive success of first clutches was not directly affected by the duration of access to males. Remating positively affected the probability of producing a second clutch, and the proportion of viable offspring. Remating by females also affected the reproductive success of males: fewer second clutch eggs were fertilized with stored sperm in unrestricted than restricted females. Sperm presence in males was high until the end of the remating period. Our results suggest a close coevolution between male and female reproductive strategies and point to facultative skipping of second broods when fitness benefits are small. This shows that behavioural strategies are at least partially responsible for multiple annual broods. These behavioural strategies are likely to be widespread, given the multitude of taxa raising multiple broods in some but not all years, and given that in most taxa some but not all individuals produce multiple annual broods. (C) 2016 The Association for the Study of Animal Behaviour. Published by Elsevier L

关键词： High-speed punch machine   Clutch brake system   Reliability test platform   Torque   Dynamic response time   MODEL  

摘要： In order to obtain high-speed punch clutch brake system dynamic characteristics and achieve reliability growth, a reliability test platform for high-speed punch machine clutch brake system was designed. Clutch brake working condition was analyzed and slipping power was determined in the process of coupling and braking. And on this basis, reliability test platform was designed. By adjusting motor rotating speed and rotational inertia of components, clutch brake working state was simulated. In the aspect of testing, clutching torque, loading torque and braking torque were collected in real time by using wireless torque sensors. And dynamic response time of clutch brake system was measured by using rotary encoder and virtual instruments. The experimental results show test platform with the validity and reliability. It can be used to find the weakness of clutch brake system and offer experimental support for reliability growth of high-speed punch.

关键词： 安全离合器   传动部件   扭矩   撞击   损坏   设备   工件  

摘要： 在设备设计和改造上,需要将联轴器设置为安全离合器,当电机端扭矩过大时,安全离合器自动松开,防止撞击和磕碰,保证设备及工件的安全。根据运动的特点和环境,结合实际使用情况分析讨论了传动结构,优化性能,从而确保运行的稳定性。