单缸发动机曲柄连杆机构惯性力参数调整研究

主轴倾角和不平衡率是控制曲柄连杆机构惯性力对发动机振动影响的两个重要参数。分析了曲柄连杆机构惯性力参数主轴倾角和不平衡率的计算方法,给出了主轴倾角、一阶最大惯性力和一阶最小惯性力在不同合成旋转质量偏置角度范围内的数学表达式;讨论了主轴倾角和不平衡率随旋转质量与往复质量比值以及合成旋转质量偏置角度变化的关系;通过软件分析与计算,以在曲柄连杆机构曲柄轴上钻孔去重的方式调整了主轴倾角和不平衡率。为曲柄连杆机构惯性力参数设计和实验调整提供了技术参考。     

发动机曲柄连杆机构连杆质量的优化配置

利用在三维造型软件中生成的发动机曲柄连杆机构的三维物理样机模型，在ADAMS软件中生成可用于动力学仿真的虚拟样机模型，通过对发动机曲柄连杆机构的惯性力的理论分析和在ADAMS中进行动力学仿真，在此基础上利用AD-AMS软件进行了曲柄连杆机构连杆质量的优化配置仿真，通过优化可以找出连杆的最佳质心位置，使机构的惯性力和惯性力矩最小。从而提高机构的动力学性能，提高设计效率。     

基于虚拟方法的发动机曲柄连杆机构优化设计

为降低多缸发动机曲柄连杆机构的振动,根据多刚体动力学理论,建立了参数化的曲柄连杆机构动态仿真模型,克服了传统的双质量模型中采用惯性力静力等效法的误差,快速获取其动力学特性数据;并结合对机构内主要件强度的有限元分析,改进了主要运动件的原始结构。通过以上工作,改善了曲柄连杆机构的动态特性,降低了发动机的振动,为曲柄连杆机构的优化设计提供了一种可借鉴的方法。     

汽车发动机总成动平衡机

一、引起发动机振动的力汽车发动机在工作过程中力的因素很多,由此而引起的振动也很复杂。其中如曲柄连杆机构旋转时的离心惯性力,往复运动部件的往复惯性力,以及曲轴因扭矩而产生的形变等,都是引起振动的主要因素。     

这台柴油机大修后为什么抖动?

工程机械上使用的柴油机与汽油机相比,压缩比大,工作强度高,曲柄连杆机构笨重,发动机工作时,曲柄连杆机构产生的惯性力很大。为了平衡惯性力,减少振动,设计制造时在结构上都采取了相应的措施,如:采用多缸设计、     

惯性力静力等效法计算误差的模拟研究

在计算柴油机曲柄连杆机构运动过程中的惯性力时,由于理论计算公式过于复杂,通常将曲柄连杆机构中的连杆和曲柄按静力等效的原则进行简化。这里用多体系统MBS（Muhi—Bodv System）动力学模拟方法,以S195柴油机为例研究了静力等效法计算曲柄连杆机构惯性力的误差。以期为单缸柴油机曲轴平衡块和辅助动平衡机构的设计提供依据。     

单轴平衡法在摩托车发动机设计中的应用

摩托车发动机通过曲柄连杆机构,将活塞在气缸内的往复运动转变为曲柄的旋转运动。在工作过程中曲轴、连杆、活塞等部件将产生周期性变化的旋转惯性力和往复惯性力,引起发动机受力不平衡,造成了整车的振动、噪声等一系列问题,如何消除这种不平衡力带来的影响具有很重要的意义。本文通过对比几种平衡方法对摩托车发动机平衡进行了分析。研究表明采用单轴平衡法对发动机进行动平衡处理,其设计过程较为方便,也是目前使用最广泛的。采用单轴平衡后,理论上采用单轴平衡法可完全消除一阶往复惯性力和旋转惯性力。     

用解析法对摆盘连杆机构与曲柄连杆机构动力学特性的对比分析

对用于轴向活赛式发动机的摆盘连杆机构进行了动态静力学分析，揭示了影响其工作能力的主要参数；提出了作用力向量图的概念及绘制方法，通过算例获得有关参数的量值，绘制向量图，为与曲柄连杆机构动力学特性对比、评价摆盘连杆机构提供了有力论据。     

柴油机动平衡问题的多体系统动力学仿真

如何确定曲柄连杆机构中平衡块的几何形状、质量特性参数以及辅助平衡装置的方案和参数，是柴油机设计人员需要考虑的主要问题之一。将三维CAD软件Pro-E和多体系统（MBS）动力学仿真软件Workingmodel 3D结合起来，建立了单缸柴油机曲柄连杆机构的多体系统动力学分析模型，并用该模型仿真研究了S195柴油机曲柄连杆机构在额定转速下的动平衡问题，为柴油机动平衡问题的分析计算及平衡装置的设计提供了一种新的方法。     

4100型内燃机曲柄连杆机构动力学仿真分析

利用动力学仿真模块对4100型内燃机进行动力学仿真。应用Solidworks对曲柄连杆机构进行三维建模。在只受重力,视曲柄连杆机构模型为刚性体的环境下,对内燃机的动力学进行仿真计算,得到活塞、连杆等机构的特性曲线和转矩曲线,对理论结果与仿真结果进行对比分析,得到曲柄销和主轴承的受力曲线。这些仿真分析结果为内燃机的动力学分析,惯性力平衡和内燃机的减振和振动分析提供一定的设计参考,为进一步改进设计提供参考。     

非惯性系下平面连杆机构动态静力分析的键合图

介绍非惯性系下平面连杆机构动态静力分析的键合图法。给出非惯性系平面连杆机构键合图模型的建立方法。基于键合图的基本概念,推导出便于计算机自动生成的机构平衡力矩运动副约束反力的统一公式。将约束反力视为未知热源加在机构键合图相应的０－结处,克服微分因果关系给建立机构平衡力矩及运动副约束反力统一公式所带来的极大的代数困难,通过实例表明本文方法的有效性。     

Dynamic stability analysis of rotating asymmetric cross-section blade packets

In this paper static and dynamic stability of rotating asymmetric cross-section two-bladed packets subjected to uniform radial periodic force are studied using the finite element method. The effects of various parameters such as shroud dimensions, stagger angle, rotational speed and distance of shear center from the centroid on the stability of the blade packets are presented. The numerical results indicate that the coupling effect is important in frequency modes depending on shear center distance from the centroid. The increase in stagger angle makes the two-bladed packet less stable. However, the increase in rotational speed makes the two-bladed packet more stable.     

Experimental studies of the dynamic compliance of a machine with parallel kinematics

Results of experimental studies of the dynamic compliance of the bearing system of a machine are presented. The system is based on a mechanism of parallel structure (the Gough-Stewart platform). The dynamic compliance of the bearing system was studied under the effect of the centrifugal force of a rotating mandrel with a displaced center of mass or a stepwise force. The plots of the dynamic compliance obtained for different configurations of the bearing system are presented.     

Simulation of the axial hydromechanical effect in gyroscopes with a spherical hydrodynamic suspension

The effect of generation of an axial inertial hydromechanical force applied to a floating rotor in gyroscopes with a spherical hydrodynamic suspension that are used as flight directors on board airborne vehicles rotating with respect to the longitudinal axis is studied. The mathematical model of the dependence of the axially inertial hydromechanical force on the intensity of variations in the rotation speed of a spherical gyroscope chamber is developed and experimentally tested.     

Dynamic stability analysis of pretwisted aerofoil cross-section blade packets under rotating conditions

This paper presents a finite element model for the static and dynamic stability of a rotating pretwisted aerofoil cross-section two-bladed packet subjected to uniform radial periodic force. The effects of various parameters such as shroud dimensions, pretwist angle, stagger angle, rotational speed and distance of shear center from the centroid on the stability of the blade packets are presented. The numerical results show that pretwist angle and the coupling effect are important in high-frequency modes depending on shear center distance from the centroid on dynamic stability regions. The increase in stagger angle makes the pretwisted two-bladed packet less stable. However, the increase in rotational speed makes the pretwisted two-bladed packet more stable.     

水力旋流器内科里奥利力的量级分析研究

科里奥利力是在旋转坐标系中由于物体相对于旋转坐标系运动所产生的一种惯性力,简称科氏力。水力旋流器的内部流场是高速旋转的离心分离流场。本研究采用计算流体力学方法模拟水力旋流器内高浓度分散相的分布,对颗粒受到的科氏力进行分析。RSM模型用于描述流场的湍动特性,LPT模型对颗粒相的运动进行追踪,模拟结果与试验数据的吻合性较好。结果表明,在水力旋流器内,由于锥体段的湍流强度较高,科氏力的方向具有较强的随机性。在切向方向,随粒径增大,曳力和压力梯度力递减而科氏力递增,当粒径增大到52μm时,科氏力的量级与曳力相当,此时科氏力的作用是不可忽略的。     

电磁式在线自动平衡头结构参数的混沌优化

介绍电磁式在线自动平衡头的工作原理,该机构利用电磁力,拖动旋转中的平衡质量,实现在线动平衡。目前,该机构各结构参数为经验尺寸,为优化结构参数,引进混沌优化算法,提出优化目标函数,计算机仿真表明,平衡头各尺寸有最佳值,而且适当设计其它结构参数,在要求范围,轴向尺寸可达最小值。     

Design of Spherical Spiral Groove Bearings for a High-Speed Air-Lubricated Gyroscope

A spherical spiral groove gas bearing has the ability to not only support radial and axial loads simultaneously but also tolerate extensive misalignment. Thus, this bearing type is considered suitable as a supporting and lubrication component of inertial components such as gyroscopes in the fields of aerospace and navigation. In this study, we propose a numerical method for predicting static and dynamic characteristics and conduct a parametric analysis of an aerodynamic spherical bearing with rotating spiral grooves. The finite difference method and the perturbation method are used to calculate the Reynolds equation to obtain the force coefficients. Given the complicated groove distribution, as well as film discontinuity and compressibility, solving the equations numerically in the spherical coordinates system is difficult. Parameter transformation and oblique coordinate transformation are thus applied in this study to modify the Reynolds equation into the planar oblique coordinate system. An eight-point method is also utilized to deal with film thickness discontinuity. The predictions of this proposed method show good agreement with the available experimental data. Parametric studies on nominal clearance, eccentricity ratio, rotating speed, groove depth, groove angle, and perturbation frequency are then conducted to determine optimum design parameters. The results show that these factors significantly affect bearing characteristics in both the radial and axial directions.     

四列氮氢气往复压缩机外力及其平衡的分析与计算

以4M50-27.3/18.5-260型氮氢气往复压缩机为研究对象,分析了作用在其曲柄连杆机构上的各作用力,从振动的角度对其受力进行分析与分类,可知往复惯性力、旋转惯性力及倾覆力矩能传到机器外部而引起压缩机的振动,属于“外力（或外力矩）”,并用Matlab软件,计算分析且绘制了压缩机列的气体力、往复惯性力、往复摩擦力和活塞力图.利用添加基础或弹性支承或者通过各列曲拐错角的合理配置的方法,对引起振动的外力进行平衡,有效减小机器的振动与噪声.     

Free vibrations of rotating small aspect ratio pretwisted blades

Free vibration characteristics of a rotating pretwisted small aspect ratio blade, mounted on a disc at a stagger angle, are determined using classical bending theory of thin shells. Differential geometry of the blade in curvilinear coordinates are analysed and strain-displacement relations are established. The strain and kinetic energies of the rotating and vibrating blade are determined and the Lagrangian function is set up. Following the Ritz procedure, natural frequencies and mode shapes of the blade are determined. The results obtained from the present analysis compare well with some of the experimental and finite element results available in literature. Variation of natural frequencies with various parameters like pretwist, speed of rotation, stagger angle and disc radius is studied and the results are presented in a nondimensional form.