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关键词： 自动变速器   液压控制   离合器压力控制   控制阀  

摘要： 自动变速器中的液压控制系统是自动变速器的重要组成部分,其中压力控制元件是控制离合器压力能够快速、准确、稳定的关键元件。从该元件或部件的设计角度分析离合器压力控制的影响因素,能够清晰地认识该部分的元件对离合器压力控制影响的重要程度及特点。这些因素的整体汇总,不仅有助于工程师更加明了地平衡设计过程中存在的冲突,也能帮助工程师准确快速的寻找具体工况下的出现问题。

关键词： Magnetorheological clutch   actuator   backdrivable actuation   torque measurement  

摘要： This paper presents an improved design, complete analysis, and prototype development of high torque-to-mass ratio Magneto-Rheological (MR) clutches. The proposed MR clutches are intended as the main actuation mechanism of a robotic manipulator with five degrees of freedom. Multiple steps to increase the toque-to-mass ratio of the clutch are evaluated and implemented in one design. First, we focus on the Hall sensors' configuration. Our proposed MR clutches feature embedded Hall sensors for the indirect torque measurement. A new arrangement of the sensors with no effect on the magnetic reluctance of the clutch is presented. Second, we improve the magnetization of the MR clutch. We utilize a new hybrid design that features a combination of an electromagnetic coil and a permanent magnet for improved torque-to-mass ratio. Third, the gap size reduction in the hybrid MR clutch is introduced and the effect of such reduction on maximum torque and the dynamic range of MR clutch is investigated. Finally, the design for a pair of MR clutches with a shared magnetic core for antagonistic actuation of the robot joint is presented and experimentally validated. The details of each approach are discussed and the results of the finite element analysis are used to highlight the required engineering steps and to demonstrate the improvements achieved. Using the proposed design, several prototypes of the MR clutch with various torque capacities ranging from 15 to 200 N center dot m are developed, assembled, and tested. The experimental results demonstrate the performance of the proposed design and validate the accuracy of the analysis used for the development.

关键词： Type 1 diabetes mellitus (T1D)   Glucose-dependent insulinotropic polypeptide (GIP)   Glucagon-like peptide-1 (GLP-1)   Glucagon-like peptide-2 (GLP-2)   Osteocalcin (OC)   Undercarboxylated OC (ucOC) as carboxylated   OC (cOC)   Bone mineral density (BMD)  

摘要： Introduction: The relationship between the gut and skeleton is increasingly recognized as a component of the regulation of carbohydrate metabolism. The aim of our study was to assess the relationship between bone mineral density (BMD), incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), intestinotrophic peptide glucagon-like peptide-2 (GLP-2) and osteocalcin isoforms in patients with long-term type 1 diabetes (T1D) when compared to healthy controls. Methods: Eighty two patients with long term T1D, treated in the Department of Metabolic Diseases and 53 healthy controls were recruited to the study. Long term disease duration was defined as lasting for more than 10 years. The control group was selected among age- and sex-matched healthy people. Fasting blood samples were collected to measure levels of incretin hormones (GLP-1, GLP-2, GIP), two forms of osteocalcin (uncarboxylated (ucOC), and carboxylated (cOC)), and additional biochemical parameters associated with glucose and bone metabolism (HbA1c, calcium, phosphorus, 25(OH)D3, PTH). Results: Patients with T1D had higher BMI than in controls (p = 0.02). There was no difference in BMD at the lumbar spine and the femoral neck between patients with long-term T1D and healthy ones. Z-score values in both groups were within normal ranges. The level of GIP was significantly higher in T1D patients (p = 0.0002) in comparison to the healthy ones. The levels of GLP-1 and GLP-2 did not differ between T1D patients and controls. In the T1D group, strong, positive associations were found between serum levels of GLP-1 and cOC (r = 0.546, p < 0.001) and between GLP-1 and total OC (r = 0.51, p < 0.001), also after adjusting for BMI (p < 0.001 and p < 0.001, respectively). Significant positive associations were also found between serum levels of GLP-2 and cOC (r = 0.27, p = 0.013) and between GLP-2 and total OC (r = 0.25, p = 0.018), also in a multivariate regression (p = 0.009, p

关键词： Exechon   Parallel mechanism   Type synthesis   Unified kinematic analysis   5-axis machining  

摘要： To fully disclose potential configurations of parallel mechanisms (PMs) that are performance-comparable to the commercially successful Exechon, a family of one translational two rotational (1T2R) over-constrained Exechon inspired PMs is synthesized through the screw theory. The synthesized PMs are further comparatively analyzed in terms of inverse kinematics, singularity occurrence and reachable workspace based on a unified kinematic model. The kinematic analyses indicate that the inherited overconstraints benefit for eliminating the constraint singularity of all synthesized Exechon inspired PMs and the workspace distribution of an Exechon inspired PM is closely related to its topological arrangement. Based on the kinematic evaluations, a preferred configuration of 2UPR-1RPS PM ('R': revolute joint, 'U': universal joint, 'S': spherical joint, 'P': prismatic actuated joint) is selected as a candidate for 1T2R spindle head. A laboratory prototype is fabricated and experimentally tested to verify the feasibility of the type synthesis and the correctness of the kinematic analyses. By integrating the selected PM with a 2-degree of freedom sliding gantry, a full scale prototype of a novel hybrid kinematic machine tool is developed to perform 5-axis machining tasks. The well match between the machined workpiece and its designed shape fully proves the engineering potential of the synthesized PMs that are expected to be employed as the functional module to construct 5-axis serial-parallel hybrid machining devices.

标准号: SY/T 6760-2021

摘要： 本文件规定了石油天然气钻采设备中气胎离合器的型号和基本参数，技术要求、试验方法、检验规则及标志、包装、运输和贮存等。本文件适用于石油天然气钻采设备用气胎离合器的设计、制造，检验和验收。

关键词： 道路工程   轴载谱   车辆分类   车辆类型转换   当量轴载换算系数  

摘要： 随着2017版《公路沥青路面设计规范》的实施,沥青路面设计中面临着新旧车辆分类标准转换的问题。采用2015年河南省高速公路收费管理系统采集的车辆数据,提出了一种车辆类型转换方法,将原6类车型转换为《新规范》下的11类车型;经计算得到河南省轴载谱参数的代表值;根据轴载谱参数,按照《新规范》要求计算了在沥青路面设计中各种车型的当量设计轴载换算系数,确定了河南省当量设计轴载换算系数的代表值。结果表明:所提出的车辆类型转换方法可行。但在车辆超载超限严重的情况下,采用规范方法计算出的当量设计轴载换算系数仍不能准确反映实际情况。

关键词： 电磁离合器企业   库存管理   问题   对策  

摘要： 近年来,全球经济一体化发展加速,中国的市场经济也随之快速发展,库存管理在车用电磁离合器制造企业的生产经营中扮演着越来越重要的角色。库存管理直接关系到企业年度经营目标的实现与否,电磁离合器企业现已普遍出现产能过剩、库存闲置的问题。因此,电磁离合器企业亟需加强库存管理。文章分析了当前车用电磁离合器企业库存管理存在的主要问题,并提出了可行的改进方法,以期为电磁离合器企业提升库存管理水平提供参考。

关键词： 轮边桥   等高螺旋锥齿轮   Kimos软件   传动误差  

摘要： 提出了一种适用于轮边桥等高螺旋锥齿轮降低传动误差的方法,阐述了轮边桥等高螺旋锥齿轮热后难以控制传动误差的机理,通过对轮边桥的热处理变形进行分析,确定优化设计思路,使用Kimos软件对某型轮边桥等高螺旋锥齿轮进行优化,验证了该方法的可行性。

关键词： 重型拖拉机   主离合器系统   故障  

摘要： 主要介绍了重型拖拉机主离合器系统常见故障,并对故障原因进行分析研究,找出了主离合器失效主要故障现象,主要故障现象有离合器打滑、离合器分离不彻底、拖拉机起步发抖,离合器操纵沉重等,分别针对不同故障现象,对离合器系统故障分析原因,找出其影响因素,最后提出判断方法和解决方案,并对设计者和维修人员提供参考建议。

关键词： 齿轮传动   数字化设计   方案设计   知识单元  

摘要： 建立齿轮传动方案设计的知识单元,提取知识单元的运动、动力以及结构属性,依据机械运动方案设计的状态空间理论,将知识单元的运动及动力属性转换为特征矢量,从而使齿轮传动方案求解转换为矩阵计算,并将知识单元动力属性与三维参数化模型相关联,通过知识单元参数化模型的配合实现传动方案的可视化。建立齿轮传动方案的知识单元库并转换为相应的数据结构,在知识单元的串并联组合基础之上,实现知识单元混联组合的方案求解。运用VS开发工具开发齿轮传动方案设计模块,输出满足用户需求的齿轮传动方案三维模型以及方案相关详细信息。