图片介绍

HD型转叶式液压舵机大仰面 HD型转叶式液压舵机是引进国外先进技术研究开发的产品，能有效而准确地操纵方向，操舵平稳，舵角范同宽，是一种理想的操舵装置，能适应各类船舶不同的需要。     

基于三圆弧的旋叶式压缩机新型线叶片设计

与定子内壁相接触的叶片头部形状,是旋叶式压缩机的设计关键。创造性提出的基于三圆弧(Three circular arc,TCA)叶片型线的原理和导出的叶片型线的设计计算理论,为实现高效压缩的旋叶式压缩机设计提供了理论计算依据,拓宽了旋叶式压缩机的设计理论。计算机仿真与试验表明,三圆弧叶片比传统方法设计的叶片具有更好的啮合特性,完全消除了"尖点滑移"和局部磨损现象,具有均匀相对滑动;型线的形状保证了叶片头部与定子内壁密封的可靠性;叶片头部具有最简单的型线形状,易于机械加工制造;与主型线光滑连接的前、后过渡修正圆弧,使叶片与定子内壁啮合时,不成刀刃状,且利于形成油膜,改进了润滑状况,同时降低了定子、转子及转子叶片和叶片槽的加工和装配精度要求。     

基于Fe-safe软件的转叶式舵机疲劳分析及优化建议

在对800 kN·m转叶式舵机整机进行有限元静力分析的基础上,基于S-N曲线采用Fe-safe软件对整机的各个部件分别进行疲劳寿命分析,并提出轻量化设计建议。在前期舵机整机的力学分析基础上,根据第一强度理论确定结构的疲劳危险点,并结合名义应力法和线性累积损伤理论,在进一步考虑光洁度等情况下采用Fe-safe软件估算结构在设计疲劳谱下舵机主要部件的疲劳寿命。     

任意缸体旋叶式压缩机的叶片型线设计理论研究及应用

与缸体内壁相接触的叶片头部形状是旋叶式压缩机设计的关键之一。应用微分几何理论,研究出与各设计基本参数紧密相关、与缸体型线相匹配的叶片型线设计方法,从理论上保证旋叶式压缩机的运行可靠性,为实现高效压缩的旋叶式压缩机设计提供计算依据,拓宽设计理论。计算机仿真与试验表明,由设计理论获得的叶片具有很好的啮合特性,完全消除了尖点滑移和局部磨损现象,具有均匀相对滑动;型线的形状保证叶片头部与缸体内壁的运行可靠性;叶片头部具有最简单的型线形状,易于机械加工制造;与主型线光滑连接的前、后过渡修正圆弧,使叶片与缸体内壁啮合时,不成刀刃状,且利于形成油膜,改进润滑状况,同时降低缸体、转子及转子叶片和叶片槽的加工和装配精度要求。     

基于ABAQUS的转叶式舵机接触状态仿真与分析

在对800 kN·m转叶式舵机整机进行有限元准静力分析的基础上,着重研究接触件间的接触状态和位移状态。对舵机整机的力学分析,在考虑螺栓预紧力和不规则构件的网格划分等难点的基础上,通过引入非线性接触设置,模拟舵机各个部件的接触效应,分析结构接触状态发生的变化和位移。结果表明:缸体和缸盖以及缸体和静叶间虽有微小位移,但接触位移都没有贯通,没有出现漏油风险;但与结构的强度潜力相比,接触漏油是舵机的薄弱环节。     

三腔旋叶式压缩机设计

从两腔旋叶式压缩机气缸型线、叶片运动、排量分析入手,找出叶片运动及排量较优的气缸型线。并以此气缸型线为基础,设计出三腔旋叶式压缩机。在代价不高的条件下,大幅度提高其排量,以便扩大旋叶式压缩机的应用范围。     

直驱式转叶舵机的特点及关键技术

直驱式转叶舵机是一种新型船舶舵机,具有结构紧凑、控制方便、高效节能、可靠性高等诸多优点。该研究针对直驱式转叶舵机的关键技术——大功率直驱控制、转叶密封设计、系统可靠性三方面进行了详细讨论,并指出了可能的改进途径,最后对直驱式转叶舵机的应用前景进行了预测。     

基于Pro/E Mechanism的旋叶式压缩机运动仿真

建立了旋叶式压缩机叶片运动的数学模型,并运用Pro/E Mechanism模块创建旋叶式压缩机运动学仿真机构,直观、简捷地得到叶片的运动特性曲线,为旋叶式压缩机叶片运动学的分析提供了新的科学方法,同时还为进一步进行动力学分析、敏感度分析和优化设计打下了坚实的基础。     

液压系统治漏措施

液压系统泄漏的原因多为密封件老化、损坏、挤出、破裂和表面拉伤等.油液污染、密封件表面粗糙、冲击和振动造成管接头松动、密封沟槽不合格、动密封件及配合件相互磨损后间隙增大、油温过高、密封圈装配不良以及橡胶密封件与液压油不相容而变质等也都是导致泄漏的原因.     

旋转轴唇形密封件磨损仿真分析

使用有限元分析软件Abaqus对旋转轴唇形密封件的磨损进行模拟,通过UMESHMOTION用户子程序来实现密封件的动态磨损过程和控制局部区域的网格自适应划分,并基于磨损因子模型来控制橡胶的磨损速率,得到了密封件唇口轮廓形状以及接触压力随时间的演化规律.通过计算所得的主唇口磨损深度与实验值进行对比,验证了仿真方法的有效性...     

Experimental studies on the effects of reduction in gear tooth stiffness and lubricant film thickness in a spur geared system

Gears are one of the most common mechanisms for transmitting power and motion and their usage can be found in numerous applications. Studies on gear teeth contacts have been considered as one of the most complicated applications in tribology. Depending on the application, the speed and load conditions of teeth may change triggering several types of failures on teeth surface such as wear, scuffing, micro-pitting and pitting. The above-mentioned faults influence changes in vibration and acoustic signals, due to changes in operating conditions such as increase in temperature and decrease in lubricant film thickness and specific film thickness. These abnormal changes result in cumulative effects on localised or distributed faults on load bearing surfaces of gears. Such damages cause reduction in tooth stiffness and severity of damage can be assessed by evaluating the same using vibration-based signals.This paper presents the results of experimental investigations carried out to assess wear in spur gears of back-to-back gearbox under accelerated test conditions. The studies considered the estimation of operating conditions such as film thickness and their effects on the fault growth on teeth surface. Modal testing experiments have been carried out on the same gear starting from healthy to worn out conditions to quantify wear damage. The results provide a good understanding of dependent roles of gearbox operating conditions and vibration parameters as measures for effective assessment of wear in spur gears.     

Friction and Wear Characteristics of TiN Coated Vane for the Rotary Compressor in a R410A Refrigerant©

HFC is a potential alternative refrigerant for CFC, which depletes the ozone layer. The rotary compressor has been widely used for refrigeration and air-conditioning systems due to its compactness and high-speed operation. R410A, an HFC refrigerant, is used in a refrigerator compressor, but its frictional characteristic is not established. In this study, the influence of R410A refrigerant on the roller-vane surfaces was studied, and friction and wear characteristics of the TiN coated vane were investigated. The friction and wear data were obtained with a specially designed high-pressure wear tester. A testing environment charged with HFC refrigerant more closely simulates the operating conditions of a real rotary compressor. In pure oil without R410A, wear of the TiN coated vane was larger than that of the uncoated vane. But when the refrigerant was dissolved in oil, wear of the uncoated vane was larger than that of the TiN coated vane. This showed that a TiN coated vane is good relative to wear resistance in the refrigerant/lubricant mixed environment. As the rotating speed of the frictional motion increased, wear increased. But in the high-velocity region, wear decreased because the boundary lubrication is changed into the mixed lubrication in the lubrication region. As the pressure grew larger, wear volume and coefficient of friction became larger. This is because the amount of the refrigerants dissolved in oil increased and the viscosity of oil dropped as the pressure increased.     

Detection and diagnosis of surface wear failure in a spur geared system using EEMD based vibration signalanalysis

Gears are used for transmission of power, motion or both. Under increased power and higher speeds, tribological failures such as scuffing, pitting, mild wear and tooth breakage are of major concern. This paper presents the results of experimental investigations carried out to assess wear in spur gears of a back-to-back gear box under accelerated test conditions. The studies considered the estimation of specific lubricant film thickness and its effects on the fault growth on gear teeth surface. Ensemble empirical mode decomposition (EEMD) technique is used to extract the fault related features from the vibration signals acquired from the gearbox. The results highlight the advantage of EEMD technique for effective assessment of wear in spurgears.     

A new fault diagnosis algorithm for helical gears rotating at low speed using an optical encoder

Helical gears are widely used in gearboxes due to its low noise and high load carrying capacity, but it is difficult to diagnose their early faults based on the signals produced by condition monitoring systems, particularly when the gears rotate at low speed. In this paper, a new concept of Root Mean Square (RMS) value calculation using angle domain signals within small angular ranges is proposed. With this concept, a new diagnosis algorithm based on the time pulses of an encoder is developed to overcome the difficulty of fault diagnosis for helical gears at low rotational speeds. In this proposed algorithm, both acceleration signals and encoder impulse signal are acquired at the same time. The sampling rate and data length in angular domain are determined based on the rotational speed and size of the gear. The vibration signals in angular domain are obtained by re-sampling the vibration signal of the gear in the time domain according to the encoder pulse signal. The fault features of the helical gear at low rotational speed are then obtained with reference to the RMS values in small angular ranges and the order tracking spectrum following the Angular Domain Synchronous Average processing (ADSA). The new algorithm is not only able to reduce the noise and improves the signal to noise ratio by the ADSA method, but also extracts the features of helical gear fault from the meshing position of the faulty gear teeth, hence overcoming the difficulty of fault diagnosis of helical gears rotating at low speed. The experimental results have shown that the new algorithm is more effective than traditional diagnosis methods. The paper concludes that the proposed helical gear fault diagnosis method based on time pulses of encoder algorithm provides a new means of helical gear fault detection and diagnosis.     

航空装备液压舵机主泵振动及噪音原因探析

一般在航空装备液压系统中,通常会产生一种和振动相随的噪音问题.虽然噪音不属于系统本身故障,但是对于航空装备来说,却能在很大程度上降低飞行员的舒适性,增加被敌方侦测到的风险,损坏液压系统部件,严重的话还会影响飞行安全.基于此,本文主要针对航空装备液压舵机主油泵振动以及噪音问题,详细分析其具体产生原因.     

润滑和载荷状态对聚甲醛齿轮服役性能的影响

基于齿轮耐久性能试验台开展了一系列干接触/油润滑下POM(聚甲醛)-POM齿轮副承载能力试验,并测量了服役过程中的轮齿温度、磨损量、齿廓精度和齿面形貌。试验发现,POM齿轮失效形式与载荷和润滑方式有关。通过对齿面微观形貌和磨屑表征,确认干接触下POM齿轮主要磨损模式为黏着磨损与磨粒磨损,而油润滑下POM齿轮失效形式为接触疲劳失效。由于润滑油减少了齿面摩擦,降低了运行温度,延缓了齿面劣化程度,因此POM齿轮在油润滑下的承载能力明显提高。     

螺杆泵驱动装置磨损状态监测系统

螺杆泵驱动装置受力复杂,振源众多,轴承和齿轮的磨损类故障较为频繁,而常规的单项指标测试只能进行定性分析,诊断精确度不高。为此,开发了磨损状态监测系统。该系统由传感器、诊断仪主机和便携式计算机组成。通过建立设备信息库、故障模式库实现了故障特征自动提取;通过建立磨损状态分级模型,实现了部件的故障诊断及整机磨损状态的评判。实际应用中,诊断出了电机轴承磨损和驱动装置大、小齿轮磨损的故障,表明系统具有较高的应用价值。     

旋挖钻机设备油液智能分析与健康监测

为了提高油液中与设备运行状态相关信息的提取效率,获取更为完整的信息来评估设备的当前状态,提出一种设备油液监测技术——全谱技术。基于全谱法制备油液污染颗粒全谱片,首先,利用图像分割技术、自动计数算法、模糊支持向量机模型实现谱片分析流程的自动化,完成谱片信息的智能提取,以此获取反映设备运行状态的关键信息;其次,将该技术应用到旋挖钻机设备的状态监测诊断中,通过对设备液压油、齿轮油中悬浮颗粒的定性、定量分析,实现了设备当前润滑、磨损状态的定性评估,为旋挖钻机的维修维护提供了指导。结果表明,油液全谱技术能够完整、快速、准确地提取油液中包含的信息来反映设备的运行状态,具有检测效率高、分析内容丰富的特点,可进一步推广应用到其他设备的油液监测诊断工作中。     

重型汽车中桥减速器润滑油中磨损颗粒分析

重型汽车中桥减速器在工作过程中其摩擦副接触表面因相对运动而产生的磨损颗粒进入润滑油中,导致润滑油性能下降;磨损颗粒随润滑油进入摩擦副接触表面,摩擦副磨损加剧。根据重型汽车的运行特点,每隔一定里程数对减速器润滑油进行取样,综合分析在用润滑油中磨损颗粒物的大小、形貌及成分。结果表明：减速器在用润滑油中磨损颗粒主要成分是铁屑和铜屑,磨损颗粒主要来自于球面垫片（铜）及其配副的摩擦以及齿轮副间的摩擦。具体分析磨损颗粒产生过程及形成机制,为重型汽车中桥减速器中运动摩擦副的设计及制造提供理论依据。     

Use of autocorrelation of wavelet coefficients for fault diagnosis

This paper presents a novel time–frequency-based feature recognition system for gear fault diagnosis using autocorrelation of continuous wavelet coefficients (CWC). Furthermore, it introduces an original mathematical approximation of gearbox vibration signals which approximates sinusoidal components of noisy vibration signals generated from gearboxes, including incipient and serious gear failures using autocorrelation of CWC. First, the drawbacks of the continuous wavelet transform (CWT) have been eliminated using autocorrelation function. Secondly, the autocorrelation of CWC is introduced as an original pattern for fault identification in machine condition monitoring. Thirdly, a sinusoidal summation function consisting of eight terms was used to approximate the periodic waveforms generated by autocorrelation of CWC for normal gearboxes (NGs) as well as occurrences of incipient and severe gear fault (e.g. slight-worn, medium-worn, and broken-tooth gears). In other words, the size of vibration signals can be reduced with minimal loss of significant frequency content by means of the sinusoidal approximation of generated autocorrelation waveforms of CWC as reported in this paper.