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关键词： 插秧机   液压系统   错误操作  

摘要： 近几年,随着插秧机数量的递增和机插秧面积的不断扩大,插秧机的故障率呈上升趋势。对插秧机上使用的两种离合器的故障情况进行分析梳理,并提出解决措施。

关键词： 弹性不稳定性   离合器   换挡   湿式   能量密度   摩擦热   模型   机理  

摘要： 湿式多片式换挡离合器是车辆传动系统的关键部件，湿式多片式换挡离合器属于典型的环薄板结构，摩擦副在摩滑过程中非均匀温度场导致的热变形作用过程与机械转矩作用过程相互耦合，多物理过程耦合循环导致界面摩擦状态不稳定。

关键词： 液压夹套   平动   离合器  

摘要： 该文介绍一种液压夹套式平动离合器,该离合器利用液压夹套金属薄壁段受压应力变形和释放压力后金属薄壁回弹的性能实现离合功能,使用了液压油作为介质对薄壁均匀施压。经过初步结构设计及仿真设计了离合器产品。经过离合器的试验研究,考核了离合器性能,并通过试验研究的结果对仿真参数进行了修正。

关键词： 离合器   设计   校核  

摘要： 针对玉柴新开发的某发动机配套国内某汽车厂轻型校车选配Φ275/Φ180膜片弹簧离合器,对该离合器的储备系数、滑磨功、起步温升、使用寿命及操纵机构的踏板行程及踏板力等进行校核。

关键词： 片式机床   摩擦   离合器  

摘要： 本文在UG参数化设计的基础上,运用软件工程方法,根据离合器设计理论以及运用参数设计及特征造型的基本原理,对机床摩擦离合器零件进行了参数化设计系统。包括了设计要求选择、离合器结构选择、离合器零件结构和装配图设计。

关键词： 离合器   膜片弹簧   分离特性   MATLAB仿真  

摘要： 简要介绍了电控机械式自动变速器(AMT)中膜片弹簧离合器的性能特点。在此基础上,根据已有的膜片弹簧计算公式对膜片弹簧从自由状态到接合状态再到分离状态进行了深入的分析与计算,得出了压力与形变的函数关系。通过MATLAB软件对推导出的4组函数关系进行仿真,从仿真曲线可以清晰地看出压力与变形的线性关系,从而可以实现离合器的分离控制。

关键词： 车辆工程   多片离合器   热流分配系数   温度场  

摘要： 在多片离合器滑摩过程中,摩擦元件之间的热流分配系数会受厚度和材料特性的影响。建立有限厚摩擦元件的接触传热模型,用有限元耦合计算方法获得了摩擦元件热流分配系数的变化过程,并得到了摩擦元件厚度方向的温度分布。结果表明:热流分配系数在滑摩初期的表面温变时间范围内为定值,但随后会变成另一个稳态常数;半无限厚模型所得的定热流分配系数只在滑摩初始阶段适用,在长时滑摩过程中并不适用,但可用于确定初始热流分配系数。

关键词： Iron overload   Hereditary tyrosinemia   Tfr2/Hepcidin   Liver injury   Low-iron food   HEPCIDIN EXPRESSION   MOUSE MODEL   GENE   HEMOCHROMATOSIS   UROPORPHYRIA   CELLS   MICE   SP1  

摘要： Background & Aims: Iron is an essential metal for fundamental metabolic processes, but little is known regarding the involvement of iron in other nutritional disorders. In the present study, we investigated disordered iron metabolism in a murine model of hereditary tyrosinemia type I (HT1), a disease of the tyrosine degradation pathway. Methods: We analysed the status of iron accumulation following NTBC withdrawal from Fah(-/-) mice, a murine model for HT1. Liver histology and serum parameters were used to assess the extent of liver injury and iron deposition. To determine the physiological significance of iron accumulation, mice were subjected to a low-iron food intake to reduce the iron accumulation. Mechanistic studies were performed on tissues and cells using immunoblotting, qRT-PCR, adenovirus transfection and other assays. Results: Severe iron overload was observed in the murine model of HT1 with dramatically elevated hepatic and serum iron levels. Mechanistic studies revealed that downregulation and dysfunction of Tfr2 decreased hepcidin, leading to iron overload. The Fah(-/-) hepatocytes lost the ability of transferrin-sensitive induction of hepcidin. Forced expression of Tfr2 in the murine liver reduced the iron accumulation. Moreover, transcription factor Sp1 was downregulated and identified as a new regulator of Tfr2 here. Additionally, low-iron food intake effectively reduced the iron deposits, protected the liver and prolonged the survival in these mice. Conclusions: Iron was severely overloaded in the HT1 mice via the Sp1/Tfr2/Hepcidin axis. The iron overload induced liver injury in the HT1 mice, and reduction of the iron accumulation ameliorated liver injury. Lay summary: Primary and secondary iron overload is an abnormal status affecting millions of people worldwide. Here, we reported severe iron overload in a murine model of HT1, a disease of the tyrosine degradation pathway, and elucidated the mechanistic basis and the physiological significance of

关键词： friction gear   electric switch machine   friction   tests for friction and wear  

摘要： In this paper, the results of studying the efficiency of an SP-6 M switch motor have been presented. The friction clutch plays an important role during the transmission of torque from a motor to an actuator. To study a motor switch, a test rig was developed in order to determine the necessary force to move switchblades depending on the pressing force of the friction clutch. The tribological properties of the friction disk materials have been investigated using a specially designed test machine.

关键词： Compressible flows in compliant tubes   Flexible ducts with variable cross section   Fluid-structure interaction (FSI)   Visco-elastic wall behavior   Non-conservative hyperbolic systems   Well-balanced path-conservative finite volume schemes   WELL-BALANCED SCHEME   HIGH-ORDER EXTENSIONS   HYPERBOLIC SYSTEMS   SOURCE TERMS   NONCONSERVATIVE PRODUCTS   BLOOD-FLOW   LAWS   RECONSTRUCTION   FORMULATION   EQUATIONS  

摘要： Flexible tubes are widely used in modern industrial hydraulic systems as connections between different components like valves, pumps and actuators. For the design and the analysis of the temporal behavior of a hydraulic system, one therefore needs an accurate mathematical model that describes the fluid flow in a compliant duct. Hence, in this paper we want to model the fluid structure-interaction (FSI) problem given by the axially symmetric flow of a compressible barotropic fluid that flows through flexible tubes made of vulcanized rubber. The material of the tube can be described by using a visco-elastic rheology, which takes into account the strain relaxation of the material. The resulting mathematical model consists in a one-dimensional system of nonlinear hyperbolic partial differential equations (PDE) with non-conservative products and algebraic source terms. To solve this system numerically, we apply the DOT method, which is a generalized path conservative Osher-type Riemann solver for conservative and non-conservative hyperbolic PDE recently proposed in [23] and [22]. We provide numerical evidence that the proposed DOT Riemann solver is well-balanced for the governing PDE system under consideration. The method is compared to available quasi-exact solutions of the Riemann problem in the case of an elastic wall described by the Laplace law. It is also compared to available experimental data and exact solutions obtained in the frequency domain for a linear visco-elastic wall behavior. In all cases under investigation the proposed path-conservative finite volume scheme based on the DOT Riemann solver is able to produce very accurate results. (C) 2016 IMACS. Published by Elsevier B.V. All rights reserved.