活塞裙部结构研究及其对发动机性能的影响

发布时间：2018-03-02 17:01

本文选题：活塞裙部　切入点：结构设计　出处：《山东理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：活塞作为内燃机的重要零部件,其设计及制造制约着内燃机的进一步发展。活塞裙部主要在发动机运行过程中起导向作用,其结构对活塞的二阶运动有明显的影响。本文首先使用实验模拟相结合的方法探究了活塞裙部结构参数的改变对裙部刚度情况的影响,又以活塞动力学及流体润滑相关理论为基础,借助AVL公司Glide动力学分析软件,结合有限元分析、活塞温度场实验、以及活塞刚度实验得到的边界条件建立了活塞动力学模型,并研究不同活塞裙部刚度情况对活塞动力学结果的影响。此外借助一个发动机升级后造成原有活塞火力岸及缸孔拉伤失效的案例,采用Glide动力学分析软件建立的动力学模型对制定的不同改进方案进行评价并找出最佳解决方案,成功解决活塞及缸套拉伤失效,并最终使结构优化后的活塞顺利通过了实验。具体研究内容及成果如下:(1)采用实验模拟相结合的研究手法,建立了活塞体刚度矩阵,为动力学分析提供边界条件。并且探究了减重腔的布置对活塞裙部及活塞环岸径向刚度的影响,以及裙部结构参数的调整对裙部刚度情况的影响。研究发现减重腔的布置不会明显降低活塞的径向刚度,活塞裙部不同结构参数对裙部刚度的影响各不相同。(2)建立的活塞动力学计算模型中综合考虑了活塞的热态变形、弹性变形、缸套的热态变形、冷态安装变形和弹性变形、活塞和缸套接触表面粗糙峰高度、半径及密度等因素的影响,并将边界润滑模型引入到了计算中,从而使动力学计算模型与工程实际更加贴近。(3)研究了不同裙部刚度情况对活塞动力学的影响,不同裙部刚度情况分别包括:裙部刚度的大小、裙部刚度的不同分布、裙部刚度的不对称。研究发现裙部刚度情况对活塞的运动情况有直接影响,活塞裙部刚度的减小都会使活塞径向位移以及最大摆动角度增大,但活塞裙部在不同高度方向刚度的改变对活塞的动力学表现情况影响各不相同,其影响应根据具体机型的设计情况进行具体分析。适度减小活塞次推力侧刚度造成的活塞主、次推力侧的不对称设计会使活塞的最大摆角变大,另外活塞的最大敲击能量会有所增加,本文中的最大敲击能量增大了13.7%。(4)本文针对某柴油机试验后出现活塞火力岸及缸孔拉伤失效问题,使用AVL GLIDE软件建立了活塞组件动力学分析模型,对活塞二阶运动进行研究,并针对不同活塞销孔偏心、裙部及头部型线优化方案进行对比,得到了最优的改进方案,并成功解决活塞及缸套拉伤失效问题。研究表明,在设定活塞销孔偏心的时候,不仅要考虑活塞销孔偏心对活塞敲击噪声、摩擦损失等性能的影响,而且一定要考察其对活塞换向过程中与缸套的接触情况的影响。当活塞热负荷增大或二阶运动动作幅度增大时,应适当加大火力岸的直径缩减量,这样对预防火力岸和缸套发生接触有利。合理优化活塞的运动情况,不但可以提高发动机的可靠性,而且对于发动机经济性以及动力性的提升都有明显的改善。
[Abstract]:The piston is an important component of internal combustion engine, the design and manufacture of restricting the further development of internal combustion engine. The piston skirt mainly plays a guiding role in the engine operation process, has obvious effect of two order movement of the structure of piston. Methods firstly use the experiment simulation combined on the piston skirt structure parameters change stiffness of the skirt, and the piston dynamics and fluid lubrication theory, with the aid of AVL Glide dynamic analysis software, combined with the finite element analysis of piston temperature field experiment, and the piston stiffness experiment the boundary conditions established piston dynamics model, and study the stiffness of different piston skirt effect on the piston dynamics results. Due to the original piston and cylinder bore strain firepower bank failure case by use of an engine upgrade, using Glide dynamic analysis software A kinetic model to evaluate the formulation of different improvement schemes and find the best solution, successfully solve the piston and cylinder strain failure, and eventually make the piston structure optimized smoothly through the experiment. The specific research contents and results are as follows: (1) research methods by combining the experimental simulation, established the piston body stiffness the stiffness matrix, the boundary conditions for dynamic analysis. And explore the effect of weight reduction cavity arrangement on the piston skirt and piston ring bank radial stiffness, and the influence of skirt structure parameter adjustment of stiffness of the skirt. The research found that the layout will not significantly reduce the weight cavity piston radial stiffness, impact the parameters of different structure of piston skirt skirt stiffness is different. (2) the establishment of the piston dynamics calculation model considering the thermal state of the piston deformation, elastic deformation, thermal deformation of the cylinder, cold. With the deformation and elastic deformation of the piston and cylinder liner contact surface roughness height, radius and density, influence factors, and the boundary lubrication model is introduced into the calculation, so that the dynamic calculation model and practical engineering to be closer. (3) studied the effect of different stiffness of piston skirt dynamics, stiffness different skirt respectively include: skirt stiffness distribution of different size, skirt stiffness, asymmetric stiffness of the skirt. The study found that directly influence movement of stiffness of skirt of the piston, the piston skirt stiffness reduction will cause the radial displacement of piston and the maximum swing angle increases. But the piston skirt stiffness in different height direction change on the dynamic performance of the piston effect is different, its effect should be analyzed according to the design of specific models. Decreasing the piston side thrust caused by the rigidity of the times The main piston, asymmetric design thrust side will make the piston maximum pendulum angle becomes larger, the maximum striking energy will increase in the piston, the maximum striking energy increases by 13.7%. (4) of the diesel engine test after the problem of piston and cylinder bore strain firepower bank failure, the use of AVL GLIDE software analysis model is established to study the dynamics of piston, piston two order movement, and according to the different piston pin hole eccentric, skirt and head line optimization schemes are compared, and the optimal scheme has been improved, and successfully solve the failure problem of piston and cylinder strain. The results show that when setting the eccentric piston pin hole. We should consider not only the piston pin hole of the eccentric piston knock noise, friction losses and other properties, and to study its effect on the contact between the piston and cylinder in the commutation process. When the piston thermal load Increase or two order movement range increases, should be appropriate to increase the firepower of the shore diameter reduction, so favorable for the prevention of fire bank and the cylinder sleeve contact. Reasonable movement of the piston, not only can improve the reliability of the engine, and the engine of economy and power of the upgrade can be improved.

【学位授予单位】：山东理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK423

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