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关键词： free-wheeling clutches   over-running clutch   rolling stop  

摘要： Promising designs of overrunning mechanisms able to increase the reliability and competitiveness of machines and mechanisms in the oil and gas industry are considered.

关键词： Transporting belt   One-way clutch   Nonlinearity   Differential quadrature method  

摘要： In order to study the vibration reduction effect of the one-way clutch on belt-drive systems, especially on the transporting belt, an experimental platform is built. The strongest resonant areas of the midpoint of the transporting belt with and without the one-way clutch are compared. The experimental results clearly show the vibration reduction effect of the one-way clutch on the resonance of the belt-drive system. In order to determine the optimum vibration reduction parameters of the one-way clutch, a two-pulley belt-drive dynamic model coupled is established. The commonalities between numerical simulation and experimental research are the inclusion of a translating belt, a driving pulley, a driven pulley and an accessory pulley. The difference is that there is no connection between the physical parameters of the numerical simulation and experimental studies. By establishing the relationship between the longitudinal vibration and transverse vibration of the translating belt spans, the coupled governing equations of the belt-drive system are derived to describe the coupling of the transverse vibration of the transporting belt and rotation of the pulleys. The natural frequency of the belt is determined by using the amplitude spectrum of the free vibration response of the system. Numerical results illustrate that the two main parameters of the one-way clutch, the wrap spring and the pre-load have little effect on the natural vibration frequency of the belt. However, these two main parameters are very sensitive to the vibration reduction effect of the one-way clutch. Therefore, this study is very helpful to understand the optimal design of the one-way clutch.

关键词： allergic rhinitis   IL-17   leptin   osteopontin   Th17  

摘要： BackgroundRecent studies suggest that T helper 17 (Th17) cell subset, a distinct pro-inflammatory CD4+ T cell lineage, may play an important role in the pathophysiology of allergic rhinitis (AR). However, the regulation of Th17 response in allergic disease is not well characterized. MethodsThirty AR and 30 healthy children were enrolled. Serum leptin and OPN levels were measured, and their correlation with IL-17 expression was analyzed using enzyme-linked immunosorbent assay (ELISA). Th17 cell differentiation and cytokine production in peripheral blood mononuclear cell (PBMCs) stimulated by leptin and OPN and related inhibitors were analyzed by ELISA. AR mice models were also established to verify the effect of leptin and OPN on Th17 cell regulation. Immunoprecipitation was performed to explore the interaction between OPN and leptin in Th17 cells. ResultsOur results showed that elevated serum leptin and OPN in AR children were correlated with serum IL-17 level (r=.53, P<.01). The recombinant leptin and OPN enhanced Th17 responses from PBMCs synergistically through nuclear factor B (NF-B), mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase (JNK) pathway and 3 integrin receptor. The AR mice showed as more severe Th17 responses and symptoms compared with control mice. Immunoprecipitation showed that OPN and leptin may interact with each other directly, and this process may be mediated by 3 integrin. ConclusionsOur data provide evidence that upregulation of leptin and OPN promotes Th17 responses in AR, and this process may be achieved through NF-B, MAPK, and JNK pathway and 3 integrin.

关键词： Machinery  

摘要： This work is dedicated to comparative estimation of vibration activity of an initial bending double-span rotor with two types of residual imbalance (of that concentrated in the center of each span and of that skew-symmetric relative to the middle of each of the spans), which are differently located relative to the curve of the initial deflection of two types, i.e., with maximum and minimum values of the shape parameter, under transient vibrations at lower critical speeds when rundown. It is revealed that the effect of skew-symmetric imbalance on the amplitudes of transition vibrations of shafting during rundown is particularly essential for natural frequencies, to which the shapes of vibrations with the nodes at each of the spans correspond. The calculations of amplitudes were conducted for the HPR-MLPR system of a turbine of the K-300-23.5, produced by the Leningrad Metallic Plant (LMP). The results obtained were analyzed. Related problems are discussed in [3-8].

关键词： 中型拖拉机   维修要点   发动机功率   更换机油   发动机部分   离合器   停放时间   功率下降  

摘要： 发动机部分如果发动机功率、其它机况正常,需要考虑到停放时间过长,应对发动机“三滤”（空气、机油、柴油）进行更换、清洗,更换机油。如果功率下降,则需要对发动机进行整修。传动部分如果离合器结合不平稳,打滑,分离不彻底,挂挡难,有打齿声,在大忙前一定要对离合器进行维修保养,及时更换摩擦片,调整好主副摩擦片间隙、调整离合器踏板行程。

关键词： 双离合器   变速器   NEDC工况   传动效率  

摘要： 变速箱是整车动力总成关键零部件之一,其传动效率是整车油耗的重要影响因素。文章以某国产城市SUV搭载的6DCT变速箱为研究对象,在三电机变速箱性能试验台上,基于NEDC工况,利用输入电机模拟发动机开展动态传动效率测试,验证其在整车动力总成中动力匹配的水平。

关键词： 振动与波   传动系统   扭转振动   离合器   性能参数优化  

摘要： 研究离合器性能参数对汽车传动系扭振的影响规律,并解决某车辆因离合器参数匹配不当导致的传动系统扭振过大问题。首先对离合器的变刚度与变阻尼等非线性因素进行研究,建立离合器传递力矩计算的非线性数学模型;然后研究汽车传动系统的动力学建模方法;最后根据传动系统动力学建模方法并考虑离合器的非线性因素,建立研究离合器性能参数影响的五自由度汽车传动系扭转振动仿真优化模型。基于建立的五自由度汽车传动系扭转振动仿真模型,以实测发动机转速数据为激励,对某前置后驱柴油车离合器从动盘的性能参数进行优化。将优化前后的离合器进行装车测试,对比分析变速箱输入轴的扭振情况。测试结果表明:优化后的离合器对传动系统的扭转振动衰减更加有效,整车NVH性能得到明显改善。建立的优化模型对同类结构车型离合器从动盘性能的参数优化具有指导意义。

关键词： 湿式离合器   SAE#2试验台   摩擦转矩   动力学模型   转动惯量   测试误差系数  

摘要： 为通过摩擦转矩试验准确得到湿式离合器真实传递的摩擦转矩,建立了SAE#2试验台动力学模型,并基于试验台两摩擦副和六摩擦副湿式离合器摩擦转矩测试对动力学模型进行了验证.随后提出了摩擦转矩测试误差系数以表征离合器真实传递摩擦转矩相对于测得转矩的增大程度,并对离合器主动端转动惯量和系统附加惯量对摩擦转矩测试误差系数的影响规律进行了研究.结果表明：转速转矩传感器测得的转矩并不是离合器真实传递的摩擦转矩,而是转速转矩传感器主动部分的惯性转矩,且小于离合器真实传递的摩擦转矩.随着离合器主动端转动惯量的增大,摩擦转矩测试误差系数线性增大;随着系统附加惯量的增大,摩擦转矩测试误差系数逐渐减小且减小速度逐渐减缓.

关键词： 混合动力   逻辑门限   状态判断   离合器   控制  

摘要： 通过对并联混合动力汽车的离合器进行研究,建立了基于逻辑门控制策略的状态判断模型以及其工作过程模型。分析了离合器在并联混合动力汽车运行中的控制原理,建立了控制模型;通过在Matlab/Simulink平台中对离合器的状态判断及工作状况进行仿真分析,论证了逻辑门控制在并联混合动力汽车离合器控制中的可行性。结果表明,逻辑门限控制策略能有效判断离合器的工作状态,进而执行并实现并联混合动力汽车中离合器的换挡、制动及能量切换等工作。

关键词： 重型车   离合器   操纵系统   响应速度  

摘要： 主要介绍重型车液压控制气助力式离合器操纵系统的工作原理,并结合重型车离合器操纵出现的实际问题,分析离合器助力器对操纵系统响应速度的影响,提出部分改进建议并进行验证。