平面低副四杆机构极位夹角的研究

对平面低副四杆机构极位夹角的定义进行了探究.提出了一种可以解决实际问题的全新概念,扩展了平面低副四杆机构极位夹角的取值范围,更符合工程实际,具有较强的实用性,为设计出急回程度更大的机械提供了依据.     

平面低副四杆机构极位夹角及行程速比系数分析

通过对平面低副四杆机构极位夹角传统定义的分析,根据机构中各杆长的变化,对极位夹角的定义进行了扩展,在此基础上对行程速比系数的取值范围进行了合理的选择。     

平面四杆机构的极位夹角及行程速比系数分析

通过对平面四杆机构急回特性的分析,重新对极位夹角进行了定义,克服了现行众多教科书中的行程速比系数K与极位夹角θ的关系式在应用上的局限性,分析了行程速比系数的变化范围,并从工程实际出发,总结了平面四杆机构行程速比系数的合理取值。     

平面四杆机构急回特性的讨论及应用

急回特性是平面四杆机构的一个重要特性，主要以曲柄摇杆机构为例，分析了平面四杆机构急回运动特性。合理选择行程速度变化系数K、极位夹角θ，对提高工业机械的生产效率具有重要的意义。     

关于平面连杆机构极位夹角的定义等几个问题的新探讨

本文提出了平面连杆机构极位夹角的新定义;推导出了无急回运动特性型、Ⅰ型和Ⅱ型曲柄摇杆机构的杆长关系,以及传动角γ为最小值和最大值时曲柄相应的位置。     

对铰链四杆机构极位夹角定义问题的探讨

对铰链四杆机构极位夹角的定义问题进行了探讨，提出的有关概念清晰明了，避免了老定义存在的三个问题。     

平面连杆机构的极位夹角及铰链四杆机构的尺寸关系——兼评现有机原教材中的几个基本概念

平面连杆机构的极位夹角是表征机构(包括多杆机构)急回运动特性的参数;铰链四杆机构基本类型(即曲柄摇杆机构,双曲柄机构和双摇杆机构)的尺寸关系给出相应机构构件尺寸的取值范围(或存在条件),规定机构尺度综合的可行域。然而,现有机原教材在论述这些问题时,概念是模糊的。     

平面四杆机构的蜕变位置研究

本文对平面四杆机构的蜕变位置进行了研究,给出了平面四杆机构蜕变位置的定义和分类,论证了平面四杆机构处于蜕变位置的条件,分析了平面四杆机构处于蜕变位置的特性,论述了蜕变位置的消除方法和利用措施。     

平面连杆机构极位夹角定义的探讨

急回平面连杆机构实现了机构工作行程的慢速进给和空间行程的快速退回，从而提高了生产率，而平面连杆机构的急回特性与其极位夹角θ密切相关，现行的众多教科书中对极位夹角的定义和锐角的取值范围，限制了书中所确定的行程速比系数k与极位夹角θ的关系式的通用性，本文对极位夹角θ的新定义解决了这个问题，并通过实例说明了其正确性和可行性。     

关于曲柄摇杆机构之极位夹角和最长杆的两套命题及证明

提出了I型、Ⅱ型平面曲柄摇杆机构极位夹角取值范围的重要命题及证明和I型、Ⅱ型和O型平面曲柄摇杆机构最长杆归属的重要命题及证明.这两大命题的提出及证明,有助于加深对平面曲柄摇杆机构性质的理解和认识.     

曲柄摇杆机构依据最佳传力性能的图解优化设计

本文讨论了平面连杆机构中有关行程速比系数和极位夹角的概念问题,分析了极位夹角在曲柄摇杆机构中的取值范围及其对机构传力性能的影响,并在此基础上提出了简便易行的图解优化设计方法。     

曲柄摇杆机构极位夹角新定义及按K值图解设计方法的探讨

就曲柄摇杆机构急回运动分析中所涉及到的几个问题 ,如曲柄摇杆机构极位夹角 θ的定义问题、行程速比系数 K的表达式以及根据 K值图解设计四杆机构的方法提出了自己的一些新的见解     

用快速傅里叶变换进行球面四杆机构连杆轨迹综合

根据给出的球面四杆机构连杆轨迹的数学模型,借助傅里叶级数这一数学工具,对连杆轨迹的谐波成分进行理论分析,发现连杆轨迹的谐波成分与其相应转角函数谐波特征参数和机构尺寸参数的内在联系。确定球面四杆机构的基本尺寸型,在此基础上建立包含600余万组机构基本尺寸型的球面四杆机构连杆轨迹的谐波特征参数数值图谱库。利用傅里叶级数理论建立球面四杆机构处于空间任意位置时连杆曲线的数学方程,推导出计算机构的实际安装尺寸、连杆上点的位置和机构安装尺寸参数的理论计算公式。利用建立的谐波特征参数数值图谱和推导的理论公式解决了球面四杆机构的轨迹综合问题,最后给出算例证明本方法的可行性。     

A comprehensive genetic algorithm for design optimization of Z-bar loader working mechanism

The operation mechanism is generally considered as a key component of a wheel loader. Its working performance has great influence on the service life, stability, efficiency and economy of the loader. This paper establishes a mathematical model of Z-bar loader mechanism in polar coordinate with four-bar linkage and six-bar Watt linkage synthesis, investigates the working performance, such as mechanism transmission ratio, carry stability, parallelism, dumping in any position, bucket flat setting, maximum dig depth, extreme transmission angle and so on. Then we explore new design methods of joint-position of Z-bar loader linkage between tilt cylinder and loader frame to perfect some of the performance. A new method, comprehensive genetic algorithm, is presented to optimize non-linear equation with multi-constraints, and the results improve the multidisciplinary performance. Furthermore, a virtual prototype of the working mechanism is modeled to simulate and verify the optimization results.     

Design of single- and multiple-dwell six-link mechanisms through design optimization

Nonlinear programming techniques are applied to a class of six-bar linkages to produce single- and multiple-dwell mechanisms. The six-bar linkage consists of a four-bar crank-rocker mechanism driving a slider crank mechanism from a coupler point. The dwell position(s) may be specified at any value of input link rotation and may last for any reasonable duration. The total stroke and the location of the slider at each dwell position may also be specified. A design optimization problem is formed which attempts to generate a linkage in which the slider link will travel in a circular path and thus produce a dwell period in the cycle at the appropriate link position. This problem is then solved by an exterior penalty function technique. The linkage model is constructed using the vector loop approach and examples for both a single- and double-dwell mechanism are included. Extensions including velocity, acceleration and transmission angle constraints are also discussed.     

Application of Boolean algebra to the analysis of the position function of the spatial four-bar linkage

The subject of this paper is the analysis of the existence of the spatial four-bar linkage position function on the variation interval (0,2 π) of an independent variable such as the position angle of one of the two links in rotation. The corresponding complex of limitations for the four-bar linkage parameters is given. Complex judgments determining these limitations are composed. The use of logical algebra gives the possibility of proving some theorems which establish the necessary and sufficient conditions for the existence of the position function.     

Über verzweigungslagen bei sphärischen viergelenkgetriebenOn the change-points of the spherical four-bar linkage

In discussing the laws of motion of a specific linkage with variable parameters, the limiting or exceptional cases where a change-point position becomes possible is frequently of interest. In this paper it is explained how to obtain the ratios of velocities for spherical four-bar linkages with change-point positions. The positions of the relative pole axes 31 and 20 (i.e. motion of the input link with respect to the output link or motion of the coupler with respect to the fixed link) are of special interest. Passing to the limit leads to the corresponding plane four-bar linkages. Two examples, one linkage from the plane and one from spherical kinematics, conclude the paper.