胶带式无级变速器轴向压力的研究综述

胶带式无级变速器的轴向压力是分析胶带式无级变速器变速机理的关键参数之一。文中阐述了胶带式无级变速器的工作原理和3种不同的调速感应机构。尤其对胶带式无级变速器的轴向压力的研究现状和成果进行了详细的介绍,分别综述了轴向压力与皮带工作半径的关系、影响轴向压力的内部结构参数和外部因素及主、从动轮皮带摩擦力的方向和皮带在带轮进出位置的变形摩擦力模型的研究现状。最后介绍了研究胶带式无级变速器轴向压力的整体思路和尚待解决的问题。     

凸轮加压宽三角带无级变速器在机床主传动设计中的应用

根据机床主传动的要求，宽三角带无级变速器的加压弹簧座位于主动轮。实验证明：这样布置满载时效率较高。本文推导了主动轮轴向力计算公式，并介绍了凸轮加压装置。由于该装置能随负载扭矩的大小自动调节轴向压力，解决了弹簧加压变速器低负载低效率问题．实验结果是满意的。     

一种主动轮加压三角带式无级变速器加压弹簧的设计

主动轮加压三角带式无级变速器的调速是通过改变主动轮侧动轮的轴向位移来实现的。本文通过对该种无级变速器主动轮侧加压系统最大、最小轴向压紧力和弹簧压缩量即动轮移动距离的分析，探讨了该种无级变速器加压弹簧的设计。     

雪橇车无级变速器变速系统力学分析研究

介绍了一种用于雪橇车的大功率胶带式无级变速器,通过对其结构和工作原理的详细描述,建立了向关的数学模型.对调速蹄块、主动轮移动锥轮、从动轮移动锥轮、扭力凸轮等进行了受力分析,给出了主、从动轮的轴向压力关系式.通过分析空载、负载时主从动轮的轴向压力间的关系,得出了CVT主、从动轮的工作半径发生改变的条件,以及胶带的张紧力可调这一重要结论.     

宽V带无级变速器中轴向压力的研究

介绍了宽V带无级变速器的工作原理,阐述了V带当量摩擦系数的计算对于宽V带无级变速器中轴向力确定的重要性,根据平带传动的欧拉公式并结合宽V带无级变速器中V带传动的实际情况,提出了摩擦力方向角,推导出了V带传动的当量摩擦系数,无级变速器在传动过程中V带紧边和松边所受拉力的变化将导致摩擦力方向角的出现,当量摩擦系数是摩擦力方向角的函数,V带从绕进带轮到绕出带轮的过程中,当量摩擦系数逐渐增大,并将包角区域分为动弧区和静弧区,分别推导了宽V带无级变速器中主动轮和从动轮轴向压力的计算公式.     

某雪橇车无级变速器调速特性分析与参数匹配

以国内某型雪橇车无级变速器为例,通过对其结构和工作原理的描述,建立了雪橇车V型胶带式无级变速器(Continuously Variable Transmission,CVT)主、从动轮的轴向力加压模型;选取主、从动弹簧的刚度及其初始压缩量4个参数作为无级变速器的主要设计参数,分析其调速特性与参数匹配;通过专用试验台的测试实验,验证了理论分析的正确性,同时测试结果也表明该CVT能够满足某型雪橇车的匹配要求。     

一种简易的机械式无级变速器

介绍了一种具有一定应用范围的机械式无级变速器。阐述了该机构的组成、工作原理及其设计计算。     

减小一独立压力控制型无级变速器压力波动的研究

本文研究一金属带型独立压力控制无级变速器（CVT）的压力特性,并建议修正降低稳态的压力波动。根据试验,监测辅助压力区在减速比内压力波动。为分析压力特性,求得包含CVT变速器液压控制模型,采用该动力学模型,研究影响压力波动的诸参数。根据仿真,我们发现液体刚度的变化是压力波动的主要原因。基于对刚度的分析,建议修正辅助控制阀供给部分刻痕来减少由辅助控制阀到CVT变速器液体供给管道刚度梯度。根据仿真和试验,采有这种液体刚度修正可以降低压力波动影响。     

钢绳环式无级变速器钢绳环轴向偏移分析

针对钢绳环式无级变速器(WR-CVT)在传动比变化过程中钢绳环的轴向偏移限制了CVT速比变化范围和承载能力这一问题,以钢带环轴向偏移为参考,建立了钢绳环轴向偏移量计算模型,计算结果显示最大偏移量为0.6369mm,最大偏移角为0.23°,该最大偏移量、最大偏移角较相同参数及条件下金属带式无级变速器（MB-CVT）钢带环的相应参数分别减小15.8%和0.04°。钢绳环在金属块鞍面圆弧槽内的滚动致使其承载能力优于钢带环。     

行星无级变速器的研究

<正>1 变速器的组成原理如图1所示,转臂1、行星轮2、内齿轮3组成了特殊的行星轮系.当机构运动时(转臂1为原动件),行星轮2节圆上的一点(柱销2′)的轨迹是一条直线,它与内齿轮3的节圆直径等长,这样就可以在体积小、结构紧凑的情况下得到一个较大的直线位移(等于四倍的转臂长),4为带有齿条4′、4″的导槽,由柱销2′带动,导槽的有效长度及齿条的有效长     

基于ADAMS的金属带式CVT变速传动机构效率分析

传动效率是金属带式CVT的一项重要性能指标,通过CVT传动机理分析了影响CVT传动效率的主要因素,并在机械动力学分析软件ADAMS平台上,针对CVT的各种功率损失原因建立ADAMS力学模型,本仿真分析了在不同的转矩比和传动比情况下金属带与锥盘间的不同功率损失形式。研究成果对优化CVT控制有一定指导意义。     

Empirical correlations for the pressure depression in externally pressurized gas bearings

The pressure depression phenomenon, usually observed in the inlet region of externally pressurized gas bearings, is predicated by constructing a simple empirical model. The same sets of experimental data, used previously by other investigators, were used to obtain the empirical equations which formulate the proposed model. Three correlations are proposed. These are the inlet pressure correlation, the minimum pressure correlation, and the position of the minimum pressure within the inlet region. Comparisons between the values obtained using these correlations and available experimental data show good agreement. Further, a comparison between the present model and another previously proposed model shows that the present one gives better results. In addition, comparison between the proposed model and available experimental data shows that the model correctly predicts pressure variations, which occur due to the effect of pressure depression, within the inlet region.     

Plastic buckling of tubes under axial compression and internal pressure

The plastic buckling and collapse of long cylinders under combined internal pressure and axial compression was investigated through a combination of experiments and analysis. Stainless-steel cylinders with diameter-to-thickness values of 28.3 and 39.8 were compressed to failure at fixed values of internal pressure up to values 75% of the yield pressure. The first effect of internal pressure is a lowering of the axial stress–strain response. In addition, at some plastic strain level, the cylinder develops uniform axisymmetric wrinkling. Under continued compression, the wrinkles grow stably, gradually reducing the axial rigidity of the structure and eventually lead to a limit load instability. All pressurized cylinders remained axisymmetric until the end of the test past the limit load.The critical stress and wavelength were established using classical plastic bifurcation theory based on the deformation theory of plasticity. The evolution of wrinkling, and the resultant limit state, were established by modeling a periodic domain that is one half of the critical wavelength long. The domain was assigned an initial imperfection corresponding to the axisymmetric buckling mode calculated through the bifurcation check. The inelastic material behavior was modeled through the flow theory of plasticity with isotropic hardening. The variations of the axial response and of the limit strain with pressure observed in the experiments were reproduced well by the model. Inclusion of Hill-type anisotropic yielding in all constitutive models was required for good agreement between predictions and experiments.     

Externally pressurized gas journal bearing with slot restrictors arranged in the axial direction

In this study, a novel rectangular slot restriction-type externally pressurized gas journal bearing was developed for use in high-speed rotating machinery, such as medical devices and industrial machines. The proposed bearing has several rectangular slot restrictors arranged in the inner surface of the bearing. To measure the bearing characteristics, a model was developed for the numerical calculation of the pressure distribution in the bearing clearance and the static characteristics of the bearing. The proposed bearing, which consists of two parts, was designed and can be manufactured using appropriate techniques. In this study, a prototype bearing with eight slots in its surface was manufactured as a test piece for fundamental tests. The diameter and length of the test bearing are 30 and 40 mm, respectively. The roundness of the bearing was measured using a three-dimensional coordinate measuring machine, and the results were used in the analysis. The pressure distribution and static characteristics obtained experimentally were found to be in good agreement with the calculated values. In the rotational tests, the rotor speed exceeded 380 Hz (22,800 rpm), and whirl vibration did not occur. During testing, the maximum rotor vibration amplitude was 0.002 mm, corresponding to an eccentricity ratio of 0.3.     

空间分度凸轮压力角的三维分析

压力角是影响空间分度机构受力情况和工作效率的一个重要参数,以圆柱分度凸轮为例,运用Matlab三维图形方式表现压力角α与θ及l三者之间的关系,便于更加直观地看清压力角α的变化规律。该方法适用于所有空间凸轮机构的压力角分析。     

四轴轮式推土机极限轴荷分析

为获得某四轴轮式推土机轮边减速器和侧传动箱的极限受力条件,分析了某四轴轮式推土机在紧急制动、抬头自救、推土抬头和爬25°坡等临界状态下的总体受力,由受力平衡条件和变形关系,建立了上述状态下各轴轴荷的计算模型,根据设计参数计算了在相应状态下的各轴轴荷,提出了该推土机轮边减速器和侧传动箱应当满足的强度条件.     

Influence evaluation of loading conditions during pressurized thermal shock transients based on thermal-hydraulics and structural analyses

The thermal hydraulic (TH) behavior of coolant water is a key factor in the structural integrity assessments on reactor pressure vessels (RPVs) of pressurized water reactors (PWRs) under pressurized thermal shock (PTS) events, because the TH behavior may affect the loading conditions in the assessment. From the viewpoint of TH behavior, configuration of plant equipment and their dimensions, and operator action time considerably influence various parameters, such as the temperature and flow rate of coolant water and inner pressure. In this study, to investigate the influence of the operator action time on TH behavior during a PTS event, we developed an analysis model for a typical Japanese PWR plant, including the RPV and the main components of both primary and secondary systems, and performed TH analyses by using a system analysis code called RELAP5. We applied two different operator action times based on the Japanese and the United States (US) rules: Operators may act after 10 min (Japanese rules) and 30 min (the US rules) after the occurrence of PTS events. Based on the results of TH analysis with different operator action times, we also performed structural analyses for evaluating thermal-stress distributions in the RPV during PTS events as loading conditions in the structural integrity assessment. From the analysis results, it was clarified that differences in operator action times significantly affect TH behavior and loading conditions, as the Japanese rule may lead to lower stresses than that under the US rule because an earlier operator action caused lower pressure in the RPV.     

考虑温度影响的表面波压力测量模型研究

薄壁压力容器是一种常见的工业设备,为了保证生产过程的顺利进行,经常需要检测它们的压力。表面波在材料表面的传播速度与表面应力有关,因此以表面应力为中间变量,建立了被测容器压力与由此引起的表面波传播时间变化之间的关系模型。考虑温度、温度应力对表面波传播速度的影响,以及温度变化引起的热变形对传播距离的影响,推导了表面波压力检测的修正模型,并对修正模型各参数进行了分析,得到简化模型。实验证明了模型的正确性。使用该方法时,压力测量最大误差为0.11 MPa,平均误差为0.045 MPa。