基于热网络法的汽车变速器热平衡分析

针对汽车变速器在工作时由于热量损耗过大导致系统温度过高的问题,对变速器进行热平衡分析。采用热网络法建立了变速器热平衡模型,并给出了热源功率、热阻以及换热系数的计算模型;利用MATLAB编程计算获得了变速器传动系统温度场分布;搭建了油温测试系统,对变速器润滑油油温进行测试,发现计算结果与测试结果接近,温升趋势吻合较好,验证了基于热网络法的变速器热平衡模型的正确性。     

拖拉机变速器对传动系噪声贡献量的特性分析

为了研究拖拉机变速器噪声对传动系统噪声的影响程度,文中以某款拖拉机变速器为研究对象,详细分析了对传动系统噪声贡献量的特性。通过噪声试验确定该拖拉机传动系统噪声数值;建立变速器箱体的有限元模型,通过箱体振动响应试验对所建仿真模型的准确性进行了验证,在此基础上得到了变速器箱体声学分析的边界条件,运用声学分析软件得到变速箱的振动辐射噪声;将试验所得传动系噪声和仿真所得变速器噪声代入声学贡献量公式计算,得出变速器噪声对传动系统噪声的贡献量。该方法为变速器噪声的降低提供了理论依据。     

基于数值模拟的螺旋锥齿轮搅油功率损失及其敏感度分析

车辆的变速器大多采用齿轮传动,在传动系统中,螺旋锥齿轮的搅油功率损失对齿轮箱的发热、齿轮效率和寿命有巨大影响。为了合理的预测变速器齿轮箱的功率损失,采用正交试验法研究了齿轮转速、润滑油温度、喷油压力、喷油嘴直径以及不同的齿轮节圆直径对螺旋锥齿轮搅油功率损失的影响和敏感程度。首先,基于齿轮箱体结构及锥齿轮对在箱体内的布置,建立了螺旋锥齿轮副喷油润滑的数值计算模型。在数值计算过程中,为提高计算稳定性和准确度,动网格技术和网格重建技术被采用。通过计算结果与试验结果的对比,验证了计算模型的有效性。研究结果表明：齿轮转速和润滑油温度对搅油功率损失影响最为显著,敏感程度排序为齿轮转速>润滑油温度>齿轮节圆直径>喷嘴直径>喷油压力。并且当齿轮转速、喷油嘴直径、喷油压力取1水平,润滑油温度以及不同的齿轮节圆直径取5水平时,搅油损失最小。研究结果为齿轮箱搅油功率损失的计算及综合传动系统的优化可提供重要参考。     

基于改进遗传算法的汽车传动系统扭转振动优化与仿真

当前,汽车传动系统扭转振动比较严重,导致车辆产生很大的噪音现象.对此,采用改进遗传算法对车辆传动系统参数进行优化,并对优化结果进行仿真验证.创建了汽车传动系统运动模型简图,推导出传动系统运动控制方程式,采用分布-集中建模方法求解角速度的响应率.构造优化目标函数,采用改进遗传算法对车辆传动系统参数进行优化.建立车辆传动系统扭转仿真模型,采用Matlab/Simulink软件对优化后的参数进行仿真.同时,与优化前进行对比和分析.仿真结果显示:采用改进遗传算法优化后,变速器和差速器的角速度峰值分别降低了25.8%和31.1%,变速器和差速器的角加速度峰值分别降低了23.1%和25.6%.采用改进遗传算法优化车辆传动系统参数,可以减少传动系统扭转振动幅度,降低车辆噪音.     

变速器振动对汽车噪声的影响分析

汽车在行驶过程中振动所产生的噪声,是评价该辆汽车性能好坏的一项重要指标,该指标直接影响乘客乘车的舒适性。车辆在工作中产生振动的主要原因是发动机系统与传动系统。变速器是传动系统的主要构成部分。因此,汽车如何降低变速器的振动逐渐受到了足够的重视。本文针对汽车变速器振动对噪声的影响进行初步研究,研究数据对提高汽车产品质量具有较大意义。     

Q45型港口牵引车变速器过热的原因

正1台使用了4585h的Q45型港口牵引车,在生产作业现场出现变速器过热故障。当其变速器油温异常升高后,车辆行驶无力,牵引力明显下降。1.传动系统工作原理该型牵引车传动系统为"液力-机械传动",采用日本TCM型液力换挡变速器。其动力传递路线为:发动机→液力     

基于解决传动系统变速器齿轮敲击的分析方法

建立一汽车传动系统6自由度动力学模型,模型中包括发动机、离合器、变速器与整车,考虑了变速器内承载齿轮副以及非承载齿轮副啮合间隙。以变速器输入轴的角加速度值为评价指标,研究模型参数变化对传动系统扭转振动的影响。利用序列二次规划法对存在非承载齿轮敲击问题的某车辆的飞轮转动惯量和离合器设计参数进行优化。根据优化结果,试制了离合器,并对新旧离合器下传动系统非承载齿轮敲齿的情况进行测试,测试了变速器处的输入轴扭转角加速度、变速器壳体处加速度以及发动机舱变速器侧声压。测试结果表明,增大飞轮侧转动惯量和离合器阻尼转矩、合理地调节离合器刚度可以衰减变速器输入轴角加速度幅值,抑制非承载齿轮副敲击现象。     

新型双锥无级变速器自适应模糊PID控制系统研究

为了解决传统车用无级变速器在行驶过程中传动比动态控制精度低、承载能力差的问题,在保证无级变速器使用要求的前提下,为提高车辆变速系统承载能力,将新型双锥无级变速器引入车辆传动系统,并提出了针对新型双锥无级变速器的自适应模糊PID传动比控制系统,最后建立整车仿真平台,对新型双锥无级变速器自适应模糊PID控制系统可行性进行研究。研究结果表明,新型双锥无级变速器相对于传统金属带无级变速器承载能力较强,通过自适应模糊PID对安装有新型双锥无级变速器车辆进行控制时与使用传统PID控制相比,车辆实际传动比、车速均与目标传动比、车速贴合性较高,能够有效地提高新型无级变速器的控制效率。     

汽车变速器传动效率理论建模与实验测试

通过对汽车变速器传动效率影响环节因素的分析,建立了变速器传动效率的理论分析模型。针对变速器的具体挡位传动结构,计算了各挡位汽车变速器的传动效率,进行了汽车变速器各挡位的传动效率实验测试。实测结果与理论计算结果有较好的一致性,从而验证了理论模型的正确性,为汽车变速器传动效率的计算预测和汽车动力传动系统的优化匹配提供了依据。     

浅谈自动变速器的特点及在我国大客车上的应用

自动变速器操纵系统ASCS（Automatic Shift Control System）是一种可以使车辆传动系统实现自动或半自动操纵系统,ASCS与传统手动固定轴式机械变速器系统MT（Manual Transmission）相结合构成了自动机械传动系统AMT（Automated Mechanical Transmission）．本文简述了重型汽车自动变速器的现状,概述了世界自动变速器生产及技术水平情况,分析了该技术发展方向和在中国的市场前景。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.